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  • Artikel  (717)
  • growth  (269)
  • wheat  (245)
  • Evolution  (207)
  • Springer  (717)
  • American Chemical Society
  • 1995-1999  (717)
  • 1
    Digitale Medien
    Digitale Medien
    Partitioning of fat and protein in energy retention of growing animals (1997)
    Springer
    European journal of nutrition 36 (1997), S. 299-302 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Energy retention ; protein retention ; fat retention ; growth ; body composition ; broilers ; Energieansatz ; Proteinansatz ; Fettansatz ; Wachstum ; Körperzusammensetzung ; Broiler
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Mit steigender Aufnahme erhöht sich der Körperfettgehalt und der Körperproteingehalt nimmt ab. Es wird oft angenommen, daß jede Zunahme im Ansatz mit mehr Fett und weniger Protein verbunden ist. Experimentelle Ergebnisse widerlegen jedoch diese Annahme. In zwei Experimenten mit männlichen Broilerhühnern wurden die Tiere auf einem Niveau von 60 % und 100 % der empfohlenen Energieaufnahme gefüttert. Die Körperzusammensetzung bei 1500 g zeigte, wie erwartet, daß sich bei steigenden Aufnahmen der Körperfettgchalt vergrößert und der Körperproteingehalt abnimmt. Fettund Proteinansatz waren linear mit der totalen Energieretention (ER) korreliert. Das bedeutet, daß jede Zunahme im Ansatz den gleichen Protein- und Fettgehalt besitzt. Wenn der Fettansatz gleich Null ist wird nur Protein, etwa 50 % des maximalen Ansatzes, retiniert. Wenn ER=O ist, wird Protein angesetzt und Fett mobilisiert. Energie-und N-Bilanzuntersuchungen bestätigen die konstante Zusammensetzung jeder Vergrößerung des Ansatzes. Die Ergebnisse beider Experimente zeigen, daß die ER aus zwei Komponenten besteht: einem basalen konstanten täglichen Proteinansatz und einer variablen zusätzlichen ER, die hauptsächlich aus Fett besteht. Der basale Proteinansatz beträgt etwa 50 % des maximalen Ansatzes. Mit steigenden Energieaufnahmen wird der basale Proteinansatz mit einer zusätzlichen Menge von Protein und Fett im konstanten Verhältnis ergänzt.
    Notizen: Summary With increasing intakes the body fat content increases and that of protein decreases. It is most often assumed that this is brought about because each increment in retention contains more fat and less protein. Experimental results, however, showed that this explanation is not true. In two experiments male broiler chickens were fed at levels between 60 and 100 % of recommended energy intake. Body composition at 1500 g showed, as expected, that with increasing intakes body fat content increased and protein content decreased. Both fat and protein retention per day were linearly related to total energy retention (ER). This means that each increment in retention has the same protein and fat content. At zero fat retention only protein was retained, about 50 % of maximal retention. At zero ER protein was retained and fat mobilized. Energy and N balance experiments confirmed the constant composition of each increment in retention. The results of both experiments show that total ER consisted of two components: a basic constant daily protein retention and a variable additional ER, mainly consisting of fat. The basic protein retention is about half of maximal retention. With increasing energy intakes the basic protein retention is combined with an additional amount of protein and fat in a constant ratio.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01617802
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  • 2
    Digitale Medien
    Digitale Medien
    Nutrient intake and protein metabolism: responses to feeding (1997)
    Springer
    European journal of nutrition 36 (1997), S. 332-335 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Nutrient intake ; protein metabolism ; protein synthesis ; growth ; energy expenditures ; Nährstoffaufnahme ; Proteinstoffwechsel ; Proteinsynthese ; Wachstum ; Energieaufwand
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Eine Zunahme von fettfreiem Gewebe tritt auf, wenn die Proteinsynthese größer ist als der Proteinabbau. Obwohl während des Wachstums von der Geburt bis zur Reife die absoluten Proteinsynthese- und -abbauraten ansteigen, nehmen dagegen die fraktionellen Raten ab. Bcide Prozesse reagieren auf die Nährstoffaufnahme. Es gibt aber deutliche Unterschiede zwischen den verschiedenen Geweben. Protein, Kohlenhydrate und Fett können den Proteinansatz bei unreifen Tieren und Kindern stimulieren. Die zugrundeliegenden Mechanismen und die Energieaufwendungen scheinen jedoch unterschiedlich zu sein.
    Notizen: Summary Lean tissue growth occurs when the rate of protein synthesis exceeds the rate of protein breakdown. Althoughabsolute rates of protein synthesis and breakdown rise during growth from birth to maturityfractional rates fall. Both these processes are sensitive to nutrient intake but responses to feeding vary greatly amongst different tissues. Protein, carbohydrate and fat can all stimulate body protein accretion in immature animals and in children but the mechanisms by which they do so, and the energy expenditures involved, seem to be different.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01617817
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  • 3
    Digitale Medien
    Digitale Medien
    Convergence across industrialised countries (1890–1989): new results using time series methods (1999)
    Springer
    Empirical economics 24 (1999), S. 23-44 
    Details
    ISSN: 1435-8921
    Schlagwort(e): Key words: Cointegration ; convergence ; growth ; Kalman filter ; JEL classifications: C22 ; O47 ; O57
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract. Augmented Dickey Fuller (ADF) and Kalman filter convergence tests are applied to annual GDPs per head to 16 industrialised countries from 1890 to 1989. Results favour convergence towards the US with a structural break following the Second World War. Estimates suggest that steady-states were higher after the war and that speeds of convergence are different across countries. The Kalman filter method dismissed the no convergence hypothesis more often than its ADF counterpart. This could explain the apparent contradiction in earlier empirical work on similar data sets (cross-section methods tended to favour convergence while time series methods were unable to dismiss the no convergence hypothesis.)
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001810050042
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  • 4
    Digitale Medien
    Digitale Medien
    Oviposition plant preference and offspring performance in the comma butterfly: correlations and conflicts (1996)
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 141-144 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Polygonia c-album ; Nymphalidae ; host-plant selection ; growth ; size
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00194743
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  • 5
    Digitale Medien
    Digitale Medien
    Effects of bean and wheat α-amylase inhibitors on α-amylase activity and growth of stored product insect pests (1995)
    Springer
    Entomologia experimentalis et applicata 75 (1995), S. 237-244 
    Details
    ISSN: 1570-7458
    Schlagwort(e): amylase inhibitor ; red kidney bean ; hard red winter wheat ; growth ; insects ; beetles ; plant resistance ; stored products ; protease inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Insect α-amylase inhibiting and/or growth inhibiting activities of proteinaceous inhibitors from red kidney bean (Phaseolus vulgaris) and hard red winter wheat (Triticum aestivum) were examined. The bean inhibitor was most effectivein vitro against α-amylases from the red flour beetle (Tribolium castaneum) and the confused flour beetle (T. confusum), followed by those from the rice weevil (Sitophilus oryzae) and yellow mealworm (Tenebrio molitor). The insect enzymes were from two- to 50-fold more susceptible than human salivary α-amylase. When the inhibitors were added at a 1% level to a wheat flour plus germ diet, the growth of red flour beetle larvae was slowed relative to that of the control group of larvae, with the bean inhibitor being more effective than the wheat inhibitor. Development of both the red flour beetle and flat grain beetle (Cryptolestes pusillus) was delayed by 1% bean inhibitor, but development of the sawtoothed grain beetle (Oryzaephilus surinamensis) and lesser grain borer (Rhyzopertha dominica) was not affected by either the bean or wheat inhibitor at the 1% level. Rice weevil adults fed a diet containing 1% bean or wheat inhibitor exhibited more mortality than weevils fed the control diet. When the wheat amylase inhibitor was combined with a cysteine protease inhibitor, E-64, and fed to red flour beetle larvae, a reduction in the growth rate and an increase in the time required for adult eclosion occurred relative to larvae fed either of the inhibitors separately. The bean inhibitor was just as effective alone as when it was combined with the protease inhibitor. These results demonstrate that plant inhibitors of insect digestive enzymes act as growth inhibitors of insects and possibly as plant defense proteins, and open the way to the use of the genes of these inhibitors for genetically improving the resistance of cereals to storage pests.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02382258
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  • 6
    Digitale Medien
    Digitale Medien
    Effects of temperature, multiple allelochemicals and larval age on the performance of a specialist caterpillar (1996)
    Springer
    Entomologia experimentalis et applicata 79 (1996), S. 335-344 
    Details
    ISSN: 1570-7458
    Schlagwort(e): alkaloid ; developmental time ; early instars ; growth ; Manduca sexta ; molting duration ; phenolics ; plant-herbivore interactions ; thermal regime
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To understand the mechanisms underlying plant-insect herbivore interactions, it is necessary to examine the simultaneous effects of temperature, food quality and larval age. We examined the simultaneous effects of three allelochemicals (tomatine, rutin and chlorogenic acid) on the performance of first and second instar Manduca sexta larvae under two representative thermal regimes 21 : 10°C and 26 : 15°C for spring and summer, respectively. Thermal regime and allelochemicals interacted to influence the time from egg hatch to ecdysis to the third instar. On average, it took about half as much time to reach the third instar at 26 : 15°C as it did at 21 : 10°C. Separately, tomatine and rutin had a negative effect on developmental time from egg hatch to the third instar, but their simutaneous effects were not additive. Chlorogenic acid significantly reduced the negative effect of tomatine. The magnitude of the allelochemical effect was larger at the cooler thermal regime compared to the warmer regime. For instance, chlorogenic acid by itself had no effect at the 26 : 15°C regime, but at the 21 : 10°C regime it significantly shortened total developmental time. The effect of chlorogenic acid on stadium duration was distinctly different for the two instars. Chlorogenic acid shortened stadium duration of first instar larvae. However, depending on thermal regime and the presence of tomatine, chlorogenic acid had a negative, positive or neutral effect on stadium duration of second instar larvae. Molting duration of second instar larvae was shortened by a half day at the warmer thermal regime but was not affected by the allelochemicals. Final larval weight was influenced by rutin and chlorogenic acid. Caterpillars fed diets containing 20 μmoles of rutin were on average 10% lighter than those fed plain diet, whereas those fed diets containing 20 μmoles of chlorogenic adic were on average 7% heavier. However, the effect of chlorogenic acid depended on thermal regime. Overall, our results indicated that: 1) temperature and food quality can interact to influence insect performance and 2) these effects are influenced by larval age.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186292
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  • 7
    Digitale Medien
    Digitale Medien
    Effects of natural and synthetic neuroactive substances on the growth and feeding of cabbage looper, Trichoplusia ni (1996)
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 443-451 
    Details
    ISSN: 1570-7458
    Schlagwort(e): beta-carboline alkaloid ; Trichoplusia ni ; harmane ; harmaline ; amitriptyline ; imipramine ; monoamine oxidase inhibitor ; tricyclics ; growth ; feeding behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In this study we investigated the effects of two naturally occurring beta-carboline alkaloids and two synthetic tricyclic antidepressants on the growth and food consumption of fifth instar larvae of the cabbage looper, Trichoplusia ni Hübner (Lepidoptera: Noctuidae). In artificial diets at high concentrations (3,000 ppm), harmane, amitriptyline, and imipramine reduce growth and feeding; harmane reduced feeding consistently at a lower concentration (200 ppm). In animals other than insects, beta-carboline alkaloids inhibit monoamine oxidase (MAO) activity and thus affect rates of disposition of serotonin and other monoamine neurotransmitters. Because brain serotonin levels are associated with variation in rates of carbohydrate and protein intake in insects, the effects of beta-carboline alkaloid ingestion on dietary self-selection behavior were examined. Choosing between diets lacking carbohydrate but containing protein and diets lacking protein but containing carbohydrate, larvae consumed a greater proportion of diet containing protein but lacking carbohydrate in the presence of harmane than in its absence. These results are consistent with beta-carboline alkaloid-mediated persistence of serotonin in the brain due to MAO inhibition. Alternatively, these results could reflect alkaloid-mediated peripheral inhibition of sucrose taste receptors influencing ingestive behaviors. That beta-carboline alkaloid ingestion is associated with changes in feeding behavior is consistent with a possible defensive role for these compounds in plant foliage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00343467
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  • 8
    Digitale Medien
    Digitale Medien
    Comparison of the effect of hydroxamic acids from wheat on five species of cereal aphids (1995)
    Springer
    Entomologia experimentalis et applicata 74 (1995), S. 115-119 
    Details
    ISSN: 1570-7458
    Schlagwort(e): wheat ; aphids ; hydroxamic acids ; DIMBOA ; DIMBOA-glucoside ; EPG ; electrical penetration graph ; feeding deterrents ; antixenosis ; plant resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Feeding behaviour of five species of cereal aphids in wheat seedlings differing in hydroxamic acid (Hx) levels, was monitored via electrical penetration graphs (EPG). Aphid species could be grouped as sensitive to the feeding deterrent effect of Hx in the seedlings (Rhopalosiphum padi, Schizaphis graminum, Sitobion avenae, andMetopolophium dirhodum) or insensitive to them (Rhopalosiphum maidis). However, when feeding behaviour was studied in artificial diets containing Hx, all species were equally sensitive to Hx. The behavour ofR. maidis was further compared with that ofR. padi through detailed EPG analysis. It was found that the insensitivity ofR. maidis to Hx in seedlings may be due to a feeding strategy avoiding contact with the compounds by decreasing the number of cellular punctures in live tissues other than sieve elements during its way to the phloem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02383002
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  • 9
    Digitale Medien
    Digitale Medien
    Hypersensitive response of wheat to the Hessian fly (1995)
    Springer
    Entomologia experimentalis et applicata 74 (1995), S. 283-294 
    Details
    ISSN: 1570-7458
    Schlagwort(e): hypersensitivity ; Hessian fly ; plant resistance ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Hessian flyMayetiola destructor (Say) larvae are able to obtain food from their host plant without inflicting mechanical damage to the plant surface, apparently by secreting substances which elicit release of nutrients from plant cells surrounding the feeding site. Cells of fully susceptible plants retain their normal appearances, while in resistant plants extensive areas of cellular collapse occur. These responses indicate that hypersensitivity is the basis of wheat's resistance to the Hessian fly. The fly's feeding mechanism more closely resembles that of a pathogen than of a phytophagous insect; correspondingly, both the genetic relationship and resistance mechanism of the host plant to the parasite are of the sorts commonly associated with bacterial and fungal pathogens.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02381793
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  • 10
    Digitale Medien
    Digitale Medien
    The folliculostatins of two dipteran insect species, their relation to matrix proteins and prospects for practical applications (1995)
    Springer
    Entomologia experimentalis et applicata 77 (1995), S. 1-9 
    Details
    ISSN: 1570-7458
    Schlagwort(e): insect endocrinology ; ecdysone ; juvenile hormone ; reproduction ; growth ; inhibin ; oostatin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The first insect folliculostatic peptide was isolated from vitellogenic ovaries of the mosquitoAedes aegypti. This decapeptide directly inhibits trypsin biosynthesis in the gut, and indirectly ovarian development. The factor was named Trypsin Modulating Oostatic Factor or TMOF by its discoverers. From the fleshfly Neobellieria bullata 2 folliculostatins have been isolated, the hexapeptide Neb-TMOF and the 19-mer Neb-colloostatin. The available data suggest that at least 2 of the 3 folliculostatins originate from matrix (like) proteins present in the ovary, a hitherto unknown source of hormones. Furthermore, one of the folliculostatins (Neb-TMOF) is a potent inhibitor of ecdysone biosynthesis by larval ring glands of fleshflies. The discovery of the dipteran folliculostatins, which do not show any resemblance to inhibins of vertebrates, may significantly contribute to a better understanding of the hormonal control of growth in insects and perhaps, in other animals as well. None of the 3 folliculostatins is blocked at its N- or C-terminus. This, in combination with the pleiotropy of their effects and the narrow species specificity make such peptides prime candidates for, testing their potential in insect pest control by means of molecular biological methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02383011
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  • 11
    Digitale Medien
    Digitale Medien
    Some prerequisites for a study of the evolution of cognition in the animal kingdom (1996)
    Springer
    Acta biotheoretica 44 (1996), S. 37-57 
    Details
    ISSN: 1572-8358
    Schlagwort(e): Animal cognition ; Evolution ; Representation ; Computation ; Significance ; Phenomenology ; Autonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A distinction is made between two definitions of animal cognition: the one most frequently employed in cognitive sciences considers cognition as extracting and processing information; a more phenomenologically inspired model considers it as attributing to a form of the outside world a significance, linked to the state of the animal. The respective fields of validity of these two models are discussed along with the limitations they entail, and the questions they pose to evolutionary biologists are emphasized. This is followed by a presentation of a general overview of what might be the study of the evolution of knowledge in animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00046434
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  • 12
    Digitale Medien
    Digitale Medien
    Within-plant distribution of Rhopalosiphum padi on wheat seedlings is affected by induced responses (1999)
    Springer
    Entomologia experimentalis et applicata 93 (1999), S. 227-230 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Rhopalosiphum padi ; cereal aphids ; wheat ; induced responses ; feeding site
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003874225681
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  • 13
    Digitale Medien
    Digitale Medien
    Comparison of Diuraphis noxia resistance in wheat isolines and plant introduction lines (1999)
    Springer
    Entomologia experimentalis et applicata 92 (1999), S. 157-164 
    Details
    ISSN: 1570-7458
    Schlagwort(e): plant resistance ; antibiosis ; tolerance ; antixenosis ; Russian wheat aphid ; wheat ; Homoptera ; Aphididae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Russian wheat aphid, Diuraphis noxia (Mordvilko), is one of the most important aphid pests of wheat, Triticum aestivum L., worldwide. Among the various pest management options, plant resistance is an economical management tactic to control D. noxia in cereal crops such as wheat. Researchers have identified D. noxia resistant germplasm and it has been incorporated into wheat. This study compared D. noxia resistance between the ‘Betta’ wheat isolines Betta-Dn1, Betta-Dn2, and Betta-Dn5 and their corresponding donor gene plant introduction (PI) lines PI 137739 (Dn1), PI 262660 (Dn2), and PI 294994 (Dn5). Although the Betta isolines and PI lines showed D. noxia resistance when compared with Betta wheat, the degree of resistance in the isolines to D. noxia was different from their corresponding PI donors. Aphid number, aphid fecundity, and biomass per aphid were not different between Betta-Dn1 and PI 137739 or Betta-Dn2 and PI 262660; however, the same parameters were significantly lower on PI 294994 compared with Betta-Dn5. This indicated that aphid resistance in PI 137739 and PI 262660 was probably governed by a single dominant gene, while the resistance in PI 294994 was controlled by more than one gene. Additionally, plant biomass reduction was aphid density dependent, which suggested that use of appropriate aphid infestation level is important when using plant biomass reduction as an indicator of resistance. Plant resistance categorization showed that there was no detectable difference in antixenosis among the seven lines evaluated. However, the higher aphid fecundity observed on PI 262660 compared with PI 137739 and PI 294994, in addition to no significant differences among the three PIs in plant biomass reduction, suggested PI 262660 was a tolerant line, while PI 137739 and PI 294994 were antibiotic lines. Plant tolerance could not be elucidated among the three Betta isolines using aphid fecundity and plant biomass reduction as indicators.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003719325094
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  • 14
    Digitale Medien
    Digitale Medien
    Influence of cereal leaf epicuticular wax on Diuraphis noxia probing behavior and nymphoposition (1998)
    Springer
    Entomologia experimentalis et applicata 89 (1998), S. 111-118 
    Details
    ISSN: 1570-7458
    Schlagwort(e): leaf surface wax ; probing behavior ; nymphoposition ; Russian wheat aphid ; wheat ; barley ; oat ; Homoptera ; Aphididae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of cereal leaf surface wax on Diuraphis noxia (Mordvilko), the Russian wheat aphid, probing behavior and nymphoposition was evaluated. Ultrastructure of leaf epicuticular wax from wheat (Triticum aestivum L.) c.v. ‘Arapahoe’ and ‘Halt’ was different from barley (Hordeum vulgare L.) c.v. ‘Morex’, and oat (Avena sativa L.) c.v. ‘Border’. Both wheat cultivars had similar rod-shaped epicuticular wax, while barley and oat plants had flakes. The chemical composition comparison of gas chromatograms also indicated that the extract of the two wheat cultivars had similar pattern of peaks, while the barley and oat leaves had similar peaks. Cereal variety significantly affected aphid probing behavior (P 〈 0.05), but wax removal using ethyl ether swab did not (P 〈 0.05). Aphids initiated significantly more probes on Border oat leaves than on Morex barley irrespective of wax removal, although total probing duration per aphid was not significantly different among the four cereals examined. Accumulative salivation duration per aphid on oat leaves with wax was significantly longer than other cereal leaves with wax, while accumulative ingestion duration per aphid on Arapahoe wheat and Morex barley was significantly longer than on oat. Nymphoposition of D. noxia on cereal leaves maintained on the benzimidazole-agar medium showed that aphids produced a greater number of nymphs on Morex barley and less on Border oat leaves, although wax removal did not affect aphid nymphoposition. Removal of leaf epicuticular waxes from the 4 cereal genotypes using ethyl ether swab indicated that the influence of wax on plant resistance to D. noxia probing and reproduction was limited. Morex barley was the most favorable, while Border oat was the least favorable cereal host of D. noxia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003458406502
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  • 15
    Digitale Medien
    Digitale Medien
    Salivation into sieve elements in relation to plant chemistry: the case of the aphid Sitobion fragariae and the wheat, Triticum aestivum (1999)
    Springer
    Entomologia experimentalis et applicata 91 (1999), S. 111-114 
    Details
    ISSN: 1570-7458
    Schlagwort(e): sieve element ; salivation ; aphid ; plant resistance ; wheat ; Sitobion fragariae ; Triticum aestivum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Extended sieve element salivation (E1 waveform in the electrical penetration graph) is a characteristic activity during early sieve element punctures, particularly in resistant plants. In order to explore a chemically-mediated mechanism of resistance associated with sieve element salivation, we compared the pattern of feeding behaviour of the aphid, Sitobion fragariae (Walker), on two cultivars of the wheat Triticum aestivum L., with different concentrations of hydroxamic acids (Hx). During 24 h of electronic monitoring, aphids dedicated over 50% of the total time to phloem ingestion from the sieve elements. Total time allocated to E1 in the experiment, time to first E1 within the experiment, time allocated to E1 before a sustained phloem ingestion (E2) and the contribution of sieve element salivation to the phloem phase (E1/[E1+E2]) were significantly higher in the high-Hx cultivar. The increased salivation in plants with higher contents of Hx suggests the existence, at least in this system, of a chemically-mediated sieve element constraint.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003628703035
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  • 16
    Digitale Medien
    Digitale Medien
    Purification and characterization of an ADP-dependent phosphofructokinase from Thermococcus zilligii (1999)
    Springer
    Extremophiles 3 (1999), S. 121-129 
    Details
    ISSN: 1433-4909
    Schlagwort(e): Key words Thermococcus ; Pyrococcus ; Thermophilic ; Phosphofructokinase ; Evolution ; ADP ; Glycolysis ; ATP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The ADP-dependent phosphofructokinase (PFK) from Thermococcus zilligii has been purified 950 fold; it had a specific activity of 190 U mg−1. The enzyme required Mg2+ ions for optimal activity and was specific for ADP. The forward reaction kinetics were hyperbolic for both cosubstrates (pH optimum of 6.4), and the apparent K m values for ADP and fructose-6-phosphate were 0.6 mM (apparent V max of 243 U mg−1) and 1.47 mM (apparent V max of 197 U mg−1), respectively. Significantly, the enzyme is indicated to be nonallosteric but was slightly activated by some monovalent cations including Na+ and K+. The protein had a subunit size of 42.2 kDa and an estimated native molecular weight of 66 kDa (gel filtration). Maximal reaction rates for the reverse reaction were attained at pH 7.5–8.0, and the apparent K m values for fructose-1,6-bisphosphate and AMP were 0.56 mM (apparent V max of 2.9 U mg−1) and 12.5 mM, respectively. The biochemical characteristics of this unique ADP-dependent enzymatic activity are compared to ATP and pyrophosphate-dependent phosphofructokinases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007920050107
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  • 17
    Digitale Medien
    Digitale Medien
    Isolation of a chymotrypsinogen B-like enzyme from the archaeon Natronomonas pharaonis and other halobacteria (1999)
    Springer
    Extremophiles 3 (1999), S. 153-161 
    Details
    ISSN: 1433-4909
    Schlagwort(e): Key wordsNatronomonas pharaonis ; Natronobacteria ; Archaea ; Serine protease ; Chymotrypsinogen ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A protease of a molecular mass of approximately 30 kDa was isolated and purified from the haloalkaliphilic archaeon Natronomonas (formerly Natronobacterium) pharaonis. The enzyme hydrolyzed synthetic peptides, preferentially at the carboxyl terminus of phenylalanine or leucine, as well as large proteins. Hydrolysis occurred over the range of pH from 6 to 12, with an optimum at pH 10. The temperature optimum was 61°C. The enzyme was nearly equally active over the range of salt concentration from 0.5 to 4 M (NaCl or KCl). A strong cross-reaction with a polyclonal antiserum against human chymotrypsin was observed. Enzymatic activity was inhibited by typical serine protease inhibitors. There was significant homology between N-terminal and internal sequences from autolytic fragments and the sequence of bovine chymotrypsinogen B; the overall amino acid composition was similar to that of vertebrate chymotrypsinogens. Evidence for a zymogen-like processing of the protease was obtained. Cell extracts from other halobacteria exhibited similar proteolytic activity and immunoreactivity. The data suggested a widespread distribution of a chymotrypsinogen B-like protease among halo- and haloalkaliphilic Archaea.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s007920050111
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  • 18
    Digitale Medien
    Digitale Medien
    Multiple class I loci expressed by the quail Mhc (1999)
    Springer
    Immunogenetics 49 (1999), S. 456-460 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Antigen processing ; Evolution ; Cell surface molecules ; Mhc ; Class I antigens
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050519
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  • 19
    Digitale Medien
    Digitale Medien
    Identification and characterization of a fish natural resistance-associated macrophage protein (NRAMP) cDNA (1999)
    Springer
    Immunogenetics 50 (1999), S. 60-66 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words NRAMP ; Fish ; Carp ; Evolution ; Expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  The mouse Lsh/Ity/Bcg locus regulates natural resistance to intracellular pathogens, and the Nramp1 gene was isolated as its candidate. Nramp is part of a small family of at least two genes, Nramp1 and Nramp2. In the present study, a full-length cDNA for carp NRAMP has been isolated and characterized. Nucleotide and predicted amino acid sequence analysis indicate that the carp NRAMP encodes a 548 amino acid membrane protein with 12 putative transmembrane domains, two N-linked glycosylation sites, and an evolutionarily conserved consensus transport motif. The peptide sequence identity among carp and human NRAMP2 is 78%, and 65% with human NRAMP1. Reverse transcription-polymerase chain reaction revealed that carp NRAMP is ubiquitously expressed. Phylogenetic analysis, using neigbor-joining, showed that the carp NRAMP protein clustered together with mammalian NRAMP2 proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050686
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  • 20
    Digitale Medien
    Digitale Medien
    Diversity and evolution of T-cell receptor variable region genes in mammals and birds (1999)
    Springer
    Immunogenetics 50 (1999), S. 301-308 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words T-cell receptors ; Variable region genes ; Evolution ; Phylogeny ; Diversity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  The receptor of a T lymphocyte (TCR) recognizes nonself antigens in the company of major histocompatibility complex (MHC) molecules presented to it by the antigen-presenting cell. The variable region of TCR is encoded by either a concatenation of variable region (TCR-V), diversity region (TCR-D), and joining region (TCR-J) genes, or a concatenation of TCR-V and TCR-J genes. The TCR-V genes exist as a multigene family in vertebrate species. Here we study the evolutionary relationships of TCR-V genes from humans, sheep, cattle, rabbits, mice, and chicken. These six species can be classified into two groups according to the frequency of γδ T-cells in their peripheral T-cell populations. The "γδ low" group of species includes humans and mice, in which γδ T-cells constitute very limited portion of the T-cell population. The "γδ high" group includes sheep, cattle, rabbits, and chicken, in which γδ T-cells comprise up to 60% of the T-cell population. Here, we compiled TCR-V sequences from the six species and conducted a phylogenetic analysis. We identified various TCR-V gene subgroups based on the analysis. We found that humans and mice have representatives from nearly all of the subgroups identified, while other species have lost subgroups to different extent. Therefore, the γδ low species have a high degree of diversity of TCR-V genes, while γδ high species all have limited diversity of TCR-V genes. This pattern is similar to that found for immunoglobulin variable region (IGV) genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050606
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  • 21
    Digitale Medien
    Digitale Medien
    Marsupial light chains: IGK with four V families in the opossum Monodelphis domestica (1999)
    Springer
    Immunogenetics 50 (1999), S. 329-335 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Marsupials ; Light chains ; Variable regions ; IGK ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  A full-length and several partial cDNAs encoding IGK light chains from the marsupial South American opossum, Monodelphis domestica, were isolated and characterized. Using these clones as a starting point, the expressed IGKV repertoire was sampled by anchored polymerase chain reaction using an IGKC-specific primer. Based on nucleotide sequences of twenty unique, expressed IGKV-J combinations, there are at least four IGKV families and two J segments. Southern blot analysis revealed each IGK-V family contains multiple gene segments totaling at least thirty-five IGKV in the opossum genome. No evidence for particular, recurrent IGKV-J combinations in the opossum IGK repertoire was seen, rather the V-J combinations appeared random and diverse. Each of the four IGKV families appear more closely related to V segments from placental mammals than to each other, suggesting the duplication of the IGKV families prior to the separation of marsupials and placental mammals more than one-hundred-million years ago. Overall, the complexity of opossum light chain V segments appears greater than that found in the heavy chain, and light chains are likely to contribute significantly to Ig diversity in this species.With this report, the homologues encoding all three classes of eutherian Ig chains, IGH, IGL, and IGK, have been described in a non-placental mammal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050609
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  • 22
    Digitale Medien
    Digitale Medien
    Major histocompatibility complex-linked MIC genes in rhesus macaques and other primates (1999)
    Springer
    Immunogenetics 50 (1999), S. 358-362 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words MHC ; MIC ; Nonhuman primates ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050614
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  • 23
    Digitale Medien
    Digitale Medien
    Isolation and mapping of the rabbit DM genes (1999)
    Springer
    Immunogenetics 49 (1999), S. 295-302 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Major histocompatibility complex ; Class II ; Antigen processing ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  Proper peptide presentation by major histocompatibility complex (MHC)-encoded class II antigens is dependent on the products of the MHC DM loci. We identified the rabbit orthologues (RLA-DMA and -DMB) of human HLA-DMA and -DMB and found that they have 76.9% and 78.8% identity with HLA-DMA and -DMB, respectively. Like classical class II MHC genes, RLA-DM genes are more closely related to human HLA-DM genes than to mouse H2-DM. Among the DM family, there is a high degree of variability at the amino terminus of the DMa chains, and length variability in the cytoplasmic tails of both DMα and DMβ. The rabbit DM genes are coexpressed with class II genes in lymphoid tissues, as are the DM genes of other mammals. The RLA-DM locus maps to the class II region of the rabbit MHC, and is flanked by the DP and DOB loci. Despite having some similarities to class II genes of bony fishes, the DM family represents a separate branch of the MHC class II family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050496
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  • 24
    Digitale Medien
    Digitale Medien
    New family of Mhc class II A genes identified from cDNA sequences in the cichlid fish Aulonocara hansbaenschi (1999)
    Springer
    Immunogenetics 49 (1999), S. 544-548 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Mhc ; Class II A ; Cichlid ; Fish ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050533
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  • 25
    Digitale Medien
    Digitale Medien
    Characterization of beta2-microglobulin in a primitive fish, the Siberian sturgeon (Acipenser baeri) (1999)
    Springer
    Immunogenetics 50 (1999), S. 79-83 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Beta2-microglobulin ; Evolution ; Sturgeon ; cDNA ; Genomic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050690
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  • 26
    Digitale Medien
    Digitale Medien
    Crustal structure, evolution, and volcanic unrest of the Alban Hills, Central Italy (1997)
    Springer
    Bulletin of volcanology 59 (1997), S. 161-170 
    Details
    ISSN: 1432-0819
    Schlagwort(e): Key words Structure ; Evolution ; Uplift ; Geodetic modeling ; Alban Hills
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  The Alban Hills, a Quaternary volcanic center lying west of the central Apennines, 15–25 km southeast of Rome, last erupted 19 ka and has produced approximately 290 km3 of eruptive deposits since the inception of volcanism at 580 ka. Earthquakes of moderate intensity have been generated there at least since the Roman age. Modern observations show that intermittent periods of swarm activity originate primarily beneath the youngest features, the phreatomagmatic craters on the west side of the volcano. Results from seismic tomography allow identification of a low-velocity region, perhaps still hot or partially molten, more than 6 km beneath the youngest craters and a high-velocity region, probably a solidified magma body, beneath the older central volcanic construct. Thirty centimeters of uplift measured by releveling supports the contention that high levels of seismicity during the 1980s and 1990s resulted from accumulation of magma beneath these craters. The volume of magma accumulation and the amount of maximum uplift was probably at least 40×106 m3 and 40 cm, respectively. Comparison of newer levelings with those completed in 1891 and 1927 suggests earlier episodes of uplift. The magma chamber beneath the western Alban Hills is probably responsible for much of the past 200 ka of eruptive activity, is still receiving intermittent batches of magma, and is, therefore, continuing to generate modest levels of volcanic unrest. Bending of overburden is the most likely cause of the persistent earthquakes, which generally have hypocenters above the 6-km-deep top of the magma reservoir. In this view, the most recent uplift and seismicity are probably characteristic and not precursors of more intense activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004450050183
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  • 27
    Digitale Medien
    Digitale Medien
    Molecular phylogeny based on the κ-casein and cytochrome b sequences in the mammalian suborder Ruminantia (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 859-866 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; κ-Casein ; Cytochrome b ; Artiodactyla ; Ruminantia ; Caprinae ; Capricornis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nucleotide sequences for the κ-casein precursor proteins have been determined from the genomic DNAs or hair roots of the Ruminantia. The coding regions, exons 2, 3, and 4, were amplified separately via the three kinds of PCRs and then directly sequenced. The primers were designed from the sequence of bovine κ-casein gene; they were applicable for the amplification of the κ-casein genes from the 13 species in the Ruminantia except exon 2 of the lesser mouse deer. These results permitted an easy phylogenetic analysis based on the sequences of an autosomal gene. A phylogenetic tree was constructed from the mature K-casein sequences and compared with the tree of the cytochrome b genes which were sequenced from the same individuals. The Cervidae (sika deer, Cervus nippon) were separated from the branch of the Bovidae on the tree of κ-casein genes with a relatively high confidence level of the bootstrap analysis, but included in the branch of the Bovidae on the tree of cytochrome b genes. The κ-casein tree indicated a monophyly of the subfamily Caprinae, although the internal branches were uncertain in the Caprinae. The tree based on the nucleotide sequences of cytochrome b genes clearly showed the relationships of the closely related species in the genus Capricornis consisting of serow (C. smatorensis), Japanese serow (C. crispus), and Formosan serow (C. swinhoei). These results would be explained by the difference of resolving power between the κ-casein and the cytochrome b sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173165
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  • 28
    Digitale Medien
    Digitale Medien
    The evolution of angiosperm seed proteins: A methionine-rich legumin subfamily present in lower angiosperm Clades (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 399-404 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Asarum ; Dioscorea ; Angiosperms ; Evolution ; Legumins ; Seed proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Analysis of legumin-encoding cDNAs fromDioscorea caucasica Lipsky (Dioscoreaceae) and fromAsarum europaeum L. (Aristolochiaceae) shows that there is an especially methionine-rich legumin subfamily present in the lower angiosperm clades including the Monocotyledoneae. It is characterized by a methionine content of 3–4 mol% which is roughly triple the methionine proportion of most other legumins. These “MetR” legumins, if present, still have to be detected in the higher angiosperms including the important seed crops. Evolutionary analysis suggests that the MetR legumins are the result of a gene duplication allowing the differentiation of legumin genes according to their sulfur content. The duplication event must have taken place before the split into mono- and dicotyledonous plants but probably after the separation of angiosperms and gymnosperms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02339013
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  • 29
    Digitale Medien
    Digitale Medien
    Integration of retroposable elements in mammals: Selection of target sites (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 685-689 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Retroposons ; Integration targets ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Genomic DNA fragments generated by the reverse transcription of cellular RNA are called retroposons. Because they are flanked by short repeats, mammalian retroposons are believed to integrate at staggered chromosomal breaks. Recently, a significant sequence pattern associated with the integration of Alu and ID repeats was identified (Jurka 1996). It is represented by the 5′ TTAAAA consensus sequence around the 5′ ends of flanking repeats of Alu, ID, as well as, of B1 and B2 retroposed elements as shown in this paper. This consensus is a potential target for enzymatic nicking which probably occurs in the complementary strand between 3′ AA and the following 3′ TTTT bases. The first four bases of the flanking repeats corresponding to the 3′ TTTT consensus sequence show some sequence variations that may be affected by complementary base pairing between the A-rich RNA tails and the DNA target sequences prior to nicking and reverse transcription. We discuss potential evidence for such base pairing based on correlated variations in nucleotide composition of different tail and target regions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02202117
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  • 30
    Digitale Medien
    Digitale Medien
    Caenorhabditis Globin genes: Rapid intronic divergence contrasts with conservation of silent exonic sites (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 101-108 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Alleles ; Evolution ; Gene conversion ; Introns ; Nematode
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Globin genes from theCaenorhabditis speciesbriggsae andremanei were identified and compared with a previously describedC. elegans globin gene. The encoded globins share between 86% and 93% amino acid identity, with most of the changes in or just before the putative B helix.C. remanei was found to have two globin alleles,Crg1-1 andCrgl-2. The coding sequence for each is interrupted by a single intron in the same position. The exons of the two genes are only 1 % divergent at the nucleotide level and encode identical polypeptides. In contrast, intron sequence divergence is 16% and numerous insertions and deletions have significantly altered the size and content of both introns. Genetic crosses show thatCrg1-1 andCrgl-2 segregate as alleles. Homozygous lines for each allele were constructed and northern analysis confirmed the expression of both alleles. These data reveal an unusual situation wherein two alleles encoding identical proteins have diverged much more rapidly in their introns than the silent sites of their coding sequences, suggesting multiple gene conversion events.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02337354
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  • 31
    Digitale Medien
    Digitale Medien
    Evolution of the response patterns to dietary carbohydrates and the developmental differentiation of gene expression of α-amylase in Drosophila (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1076-1084 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Expression patterns ; α-Amylase ; Glucose repression ; Starch induction ; Intra- and interspecific variation ; Drosophila ; Gene expression ; Regulatory genes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Intraspecific variation of α-amylase activity in D. melanogaster and D. immigrans, which is distantly related to D. melanogaster, and interspecific variation of α-amylase activity in 18 Drosophila species were examined. The amount of intraspecific variation of α-amylase activities measured in terms of coefficient of variation in D. melanogaster and D. immigrans was one-half and one-tenth or less, respectively, of the interspecific variation in 18 Drosophila species. We also surveyed the response patterns of α-amylase activity to dietary carbohydrates at the larval and adult stages. The levels of α-amylase activity depended on both repression by dietary glucose (glucose repression) and induction by dietary starch (starch induction). In general, our data suggest that glucose repression was conserved among species at both stages while starch induction was mainly observed in larvae, although the degree of the response depended on species. In D. lebanonensis lebanonensis and D. serrata, larvae expressed electrophoretically different α-amylase variants (isozymes) from those of adult flies. These results may suggest that the regulatory systems responsible both for the response to environment and developmental expression are different among species in Drosophila.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173189
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  • 32
    Digitale Medien
    Digitale Medien
    Ferritin gene organization: Differences between plants and animals suggest possible kingdom-specific selective constraints (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 325-336 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Soybean ; Ferritin ; Plant-animal ; Monocotyledons ; Dicotyledons ; Plastid ; Gene organization ; Evolution ; Intron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Ferritin, a protein widespread in nature, concentrates iron −1011−1012-fold above the solubility within a spherical shell of 24 subunits; it derives in plants and animals from a common ancestor (based on sequence) but displays a cytoplasmic location in animals compared to the plastid in contemporary plants. Ferritin gene regulation in plants and animals is altered by development, hormones, and excess iron; iron signals target DNA in plants but mRNA in animals. Evolution has thus conserved the two end points of ferritin gene expression, the physiological signals and the protein structure, while allowing some divergence of the genetic mechanisms. Comparison of ferritin gene organization in plants and animals, made possible by the cloning of a dicot (soy-bean) ferritin gene presented here and the recent cloning of two monocot (maize) ferritin genes, shows evolutionary divergence in ferritin gene organization between plants and animals but conservation among plants or among animals; divergence in the genetic mechanism for iron regulation is reflected by the absence in all three plant genes of the IRE, a highly conserved, noncoding sequence in vertebrate animal ferritin mRNA. In plant ferritin genes, the number of introns (n = 7) is higher than in animals (n = 3). Second, no intron positions are conserved when ferritin genes of plants and animals are compared, although all ferritin gene introns are in the coding region; within kingdoms, the intron positions in ferritin genes are conserved. Finally, secondary protein structure has no apparent relationship to intron/exon boundaries in plant ferritin genes, whereas in animal ferritin genes the correspondence is high. The structural differences in introns/exons among phylogenetically related ferritin coding sequences and the high conservation of the gene structure within plant or animal kingdoms suggest that kingdom-specific functional constraints may exist to maintain a particular intron/exon pattern within ferritin genes. In the case of plants, where ferritin gene intron placement is unrelated to triplet codons or protein structure, and where ferritin is targeted to the plastid, the selection pressure on gene organization may relate to RNA function and plastid/nuclear signaling.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02337543
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  • 33
    Digitale Medien
    Digitale Medien
    Sequence divergence in a family of variant surface glycoprotein genes from trypanosomes: Coding region hypervariability and downstream recombinogenic repeats (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 500-511 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Multigene family ; Recombination ; Trypanosome ; Variant surface glycoprotein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The surface of the parasitic protozoanTrypanosoma brucei spp. is covered with a dense coat consisting of a single type of glycoprotein molecule, the variant surface glycoprotein (VSG). There may be as many as 1,000 genes for VSG within the genome ofT. brucei, and the switch of expression from one to another is the phenomenon of antigenic variation. As an approach to understanding the evolution of VSG genes we have determined the genomic DNA sequences of the eight genes encoding the variant surface glycoprotein 117 (VSG) family. From these data we have observed a number of features concerning the relationships between these genes: (1) there is a region of high variability confined to the N-terminus of the coding sequence, and comparison of the sequences with the available X-ray diffraction crystal structures suggests that two of the most variable stretches within the N-terminal domain are present on surface-exposed loops, indicating a role for epitope selection in evolution of these genes; (2) the 29 nucleotides surrounding the splice acceptor site are absolutely conserved in all eight 117 VSG genes; (3) numerous insertion/deletion mutations are located within or immediately downstream of the C-terminal protein-coding sequences: (4) within 500 by downstream of the insertion/deletion mutations are one or two copies of a repeat motif highly homologous to the recombinogenic 76-bp repeat sequences present upstream of many VSG basic copy genes and the expression-linked copy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02352280
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  • 34
    Digitale Medien
    Digitale Medien
    Evolution of disintegrin cysteine-rich and mammalian matrix-degrading metalloproteinases: Gene duplication and divergence of a common ancestor rather than convergent evolution (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 263-269 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Metalloproteinase ; Disintegrin ; Evolution ; Venom ; Phylogeny ; Gene duplication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The evolution of the Metalloproteinase Disintegrin Cysteine-rich (MDC) gene family and that of the mammalian Matrix-degrading Metalloproteinases (MMPs) are compared. The alignment of snake venom and mammalian MDC and MMP precursor sequences generated a phylogenetic tree that grouped these proteins mainly according to their function. Based on this observation, a common ancestry is suggested for mammalian and snake venom MDCs; it is also possible that gene duplication of the already-assembled domain structure, followed by divergence of the copies, may have significantly contributed to the evolution of the functionally diverse MDC proteins. The data also suggest that the structural resemblance of the zinc-binding motif of venom MDCs and MMPs may best be explained by common ancestry and conservation of the proteolytic motifs during the divergence of the proteins rather than through convergent evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02338834
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  • 35
    Digitale Medien
    Digitale Medien
    The puzzle of the Krebs citric acid cycle: Assembling the pieces of chemically feasible reactions, and opportunism in the design of metabolic pathways during evolution (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 293-303 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Krebs cycle ; Evolution ; Metabolism ; Citric acid cycle ; Chemical design
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The evolutionary origin of the Krebs citric acid cycle has been for a long time a model case in the understanding of the origin and evolution of metabolic pathways: How can the emergence of such a complex pathway be explained? A number of speculative studies have been carried out that have reached the conclusion that the Krebs cycle evolved from pathways for amino acid biosynthesis, but many important questions remain open: Why and how did the full pathway emerge from there? Are other alternative routes for the same purpose possible? Are they better or worse? Have they had any opportunity to be developed in cellular metabolism evolution? We have analyzed the Krebs cycle as a problem of chemical design to oxidize acetate yielding reduction equivalents to the respiratory chain to make ATP. Our analysis demonstrates that although there are several different chemical solutions to this problem, the design of this metabolic pathway as it occurs in living cells is the best chemical solution: It has the least possible number of steps and it also has the greatest ATP yielding. Study of the evolutionary possibilities of each one-taking the available material to build new pathways-demonstrates that the emergence of the Krebs cycle has been a typical case of opportunism in molecular evolution. Our analysis proves, therefore, that the role of opportunism in evolution has converted a problem of several possible chemical solutions into asingle-solution problem, with the actual Krebs cycle demonstrated to be the best possible chemical design. Our results also allow us to derive the rules under which metabolic pathways emerged during the origin of life.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02338838
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  • 36
    Digitale Medien
    Digitale Medien
    Sequence simplicity and evolution of the 3′ untranslated region of the histone H1° Gene (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 125-134 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Histone H1° ; 3′ untranslated region ; Slippage ; Sequence simplicity ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The H1° gene has a long 3′ untranslated region (3′UTR) of 1,125 nucleotides in the rat and 1,310 in humans. Analysis of the sequences shows that they have features of simple DNA that suggest involvement of replication slippage in their evolution. These features include the length imbalance between the rat and human sequences; the abundance of single-base repeats, two-base runs and other simple motifs clustered along the sequence; and the presence of single-base repeat length polymorphisms in the rat and mouse sequences. Pairwise comparisons show numerous short insertions/deletions, often flanked by direct repeats. In addition, a proportion of short insertions/deletions results from length differences in conserved single-base repeats. Quantification of the sequence simplicity shows that simple sequences have been more actively incorporated in the human lineage than in the rodent lineage. The combination of insertions/deletions and nucleotide substitutions along the sequence gives rise to three main regions of homology: a highly variable central region flanked by more conserved regions nearest the coding region and the polyA addition site.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02337357
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  • 37
    Digitale Medien
    Digitale Medien
    Investigating hypothetical products from noncoding frames (HyPNoFs) (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 570-577 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Alternate reading frames ; Evolution ; Overlapping frames ; Homology search ; Primary sequence analysis ; Polycistronic genes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Hypothetical Products from Noncoding Frames (i.e., HyPNoFs) are hypothetical, not-coded proteins, translated from alternate reading frames (i.e., coding+1 and coding+2) of cDNAs. HyPNoFs of CD4, PKC, oncostatin, bcl-2 proto-oncogene, tumor suppressor p53, cystic fibrosis transmembrane regulator (CFTR), and tumor necrosis factors a and β were searched as query sequences vs the SWISS-PROT data bank. Homology searches carried out revealed that hypothetical products (i.e., HyPNoFs) may share high similarity with real protein products actually coded. Sequence similarity of hypothetical products to real proteins is sometimes very high, suggesting common conformational features, according to the Sander and Schneider cutoff value. This finding supports the hypothesis that eukaryotic DNA, currently considered to be monocistronic, might occasionally have polycistronic regions, carrying different protein messages on overlapping frames. As yet, polycistronic genes have been observed in viral genomes only. The presence of polycistronic regions in eukaryotic genes is likely reminiscent of an ancient strategy, rather than a present feature of the genome in eukaryotes. These data suggest that thorough investigation of HyPNoFs is likely to improve our ability to trace genes' evolution and to investigate structure-function relationships of protein and DNA sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160503
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  • 38
    Digitale Medien
    Digitale Medien
    Evolution of protamine P1 genes in mammals (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 601-607 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Prolamine ; Sperm proteins ; Evolution ; Mammals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Prolamine P1 genes have been sequenced following PCR amplification from 11 mammals representing five major mammalian orders: Rodentia (rat and guinea pig), Carnivora (cat and bear), Proboscidea (elephant), Perissodactyla (horse), and Artiodactyla (camel, deer, elk, moose, and gazelle). The predicted amino acid sequence for these genes together with previously reported sequences results in a data set of 25 different P1 genes and 30 different P1 amino acid sequences. The alignment of all these sequences reveals that prolamines are amongst the most rapidly diverging proteins studied. In spite of the large number of differences there are conserved motifs that are also common to birds such as the N-terminal ARYR followed by the triple alternating SRSRSR phosphorylation site. The central region contains 3 arginine clusters consisting of 5–6 arginines each. The C-terminus appears to be the most variable region of the protamines. Overall the molecular evolution of P1 genes is in agreement with the expected species evolution supporting that these genes have evolved vertically.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160507
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  • 39
    Digitale Medien
    Digitale Medien
    The molecular cloning of a phospholipase A2 from Bothrops jararacussu snake venom: Evolution of venom group II phospholipase A2's may imply gene duplications (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 174-179 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Snake venom ; Bothrops ; Phospholipase ; Myotoxin ; Evolution ; cDNA ; Gene duplication ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The sequence coding for a snake venom phospholipase A2 (PLA2), BJUPLA2, has been cloned from a Bothrops jararacussu venom gland cDNA library. The cDNA sequence predicts a precursor containing a 16-residue signal peptide followed by a molecule of 122 amino acid residues with a strong sequence similarity to group II snake venom PLA2's. A striking feature of the cDNA is the high sequence conservation of the 5′ and 3′ untranslated regions in cDNAs coding for PLA2's from a number of viper species. The greatest sequence variation was observed between the regions coding for the mature proteins, with most substitutions occurring in nonsynonymous sites. The phylogenetic tree constructed by alignment of the amino acid sequence of BJUPLA2 with group II PLA2's in general groups them according to current taxonomical divisions and/or functional activity. It also suggests that gene duplications may have occurred at a number of different points during the evolution of snake venom group II PLA2's.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00170670
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  • 40
    Digitale Medien
    Digitale Medien
    Phylogenetic position of Dictyostelium inferred from multiple protein data sets (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 238-246 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Cellular slime molds ; Animals ; Fungi ; Plantae ; Maximum-likelihood method ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The phylogenetic position of Dictyostelium inferred from 18S rRNA data contradicts that from protein data. Protein trees always show the close affinity of Dictyostelium with animals, fungi, and plants, whereas in 18S rRNA trees the branching of Dictyostelium is placed at a position before the massive radiation of protist groups including the divergence of the three kingdoms. To settle this controversial issue and to determine the correct position of Dictyostelium, we inferred the phylogenetic relationship among Dictyostelium and the three kingdoms Animalia, Fungi, and Plantae by a maximum-likelihood method using 19 different protein data sets. It was shown at the significance level of 1 SE that the branching of Dictyostelium antedates the divergence of Animalia and Fungi, and Plantae is an outgroup of the Animalia-Fungi-Dictyostelium clade.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00170678
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  • 41
    Digitale Medien
    Digitale Medien
    The β-tubulin gene family evolution in theDrosophila montium subgroup of themelanogaster species group (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 293-298 
    Details
    ISSN: 1432-1432
    Schlagwort(e): β-tubulin ; Evolution ; Gene cluster ; Gene dispersion ; Drosophila montium subgroup
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The β1-, β2-, and β3-tubulin genes have been mapped by in situ hybridization on the polytene chromosomes of 11 selected species (15 strains) belonging to theDrosophila montium subgroup. Although the hybridization pattern among the strains of the same species does not differ, this pattern is significantly different among the species. The β-tubulin genes in themontium subgroup seem to be organized in a cluster, or in a semi-cluster, or are completely dispersed. The clustered arrangement is found in the North-Oriental sibling speciesD. auraria, D. triauraria, andD. quadraria. The semi-clustered arrangement, wherein the β1 and β2 genes are located at the same locus while β3 is at a different one, appears in the South-Oriental speciesD. bicomuta, D. serrata, andD. birchii, as well as in the Afrotropical speciesD. diplacantha andD. seguyi. The complete separation of the genes is observed in the Indian speciesD. kikkawai andD. jambulina and in the Afrotropical speciesD. vulcana. Based on the above results, a possible mode of evolution of the β-tubulin genes in the montium subgroup is attempted. In addition, phylogenetic relationships among themontium species are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01215176
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  • 42
    Digitale Medien
    Digitale Medien
    The β-tubulin gene family evolution in the Drosophila montium subgroup of the melanogaster species group (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 293-298 
    Details
    ISSN: 1432-1432
    Schlagwort(e): β-tubulin ; Evolution ; Gene cluster ; Gene dispersion ; Drosophila montium subgroup
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The β1-, β2-, and β3-tubulin genes have been mapped by in situ hybridization on the polytene chromosomes of 11 selected species (15 strains) belonging to the Drosophila montium subgroup. Although the hybridization pattern among the strains of the same species does not differ, this pattern is significantly different among the species. The β-tubulin genes in the montium subgroup seem to be organized in a cluster, or in a semi-cluster, or are completely dispersed. The clustered arrangement is found in the North-Oriental sibling species D. auraria, D. triauraria, and D. quadraria. The semi-clustered arrangement, wherein the β1 and β2 genes are located at the same locus while β3 is at a different one, appears in the South-Oriental species D. bicomuta, D. serrata, and D. birchii, as well as in the Afrotropical species D. diplacantha and D. seguyi. The complete separation of the genes is observed in the Indian species D. kikkawai and D. jambulina and in the Afrotropical species D. vulcana. Based on the above results, a possible mode of evolution of the β-tubulin genes in the montium subgroup is attempted. In addition, phylogenetic relationships among the montium species are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186541
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  • 43
    Digitale Medien
    Digitale Medien
    Molecular and phylogenetic analysis of PCR-amplified cyclin-dependent kinase (CDK) family sequences from representatives of the earliest available lineages of eukaryotes (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 407-413 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Giardia ; Trichomonas ; CDK ; CDC ; Unicellular ; Metazoa ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cyclin-dependent kinase (CDK) and cell division control (CDC2) sequences are strongly conserved among eukaryotes and may complement the use of other sequence families in eukaryotic phylogenetic inference. We synthesized degenerate PCR primers to amplify the catalytic region of CDK homologs in representatives of the earliest available lineages of eukaryotes. CDK family sequence-based, maximum-likelihood distance measurements with neighbor joining, and Fitch-Margoliash least-squares analyses produced unrooted dendrograms that included protists, yeasts, and higher eukaryotes. Bootstrap confidence estimates supported CDK-based phylogenetic groupings among the protists, fungi, and vertebrates although resolution within these groups was often insignificant. However, Trichomonas vaginalis and Giardia lamblia exhibited two of the most divergent CDK-like sequences consistent with rRNA-phylogenetic inference of early divergence of these eukaryotic lineages. In the evolution from unicellular to multicellular organisms, a constellation of amino acid residues aligning with the human, CDK N-terminal β sheet may have undergone abrupt replacement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160311
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  • 44
    Digitale Medien
    Digitale Medien
    Evolutionary relationships of the carbamoylphosphate synthetase genes (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 813-832 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Phylogeny ; Evolution ; Carbamoylphosphate synthetase ; Dihydroorotase ; Aspartate transcarbamoylase ; Intron ; Exon ; Arginine biosynthesis ; Pyrimidine biosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Carbamoylphosphate is a common intermediate in the metabolic pathways leading to the biosynthesis of arginine and pyrimidines. The amino acid sequences of all available proteins that catalyze the formation of carbamoylphosphate were retrieved from Genbank and aligned to estimate their mutual phylogenetic relations. In gram-negative bacteria carbamoylphosphate is synthesized by a two-subunit enzyme with glutamiriase and carbamoylphosphate synthetase (CPS) activity, respectively. In gram-positive bacteria and lower eukaryotes this two-subunit CPS has become dedicated to arginine biosynthesis, while in higher eukaryotes the two subunits fused and subsequently lost the glutaminase activity. The CPS dedicated to pyrimidine synthesis is part of a multifunctional enzyme (CPS II), encoding in addition dihydroorotase and aspartate transcarbamoylase. Evidence is presented to strengthen the hypothesis that the two “kinas” subdomains of all CPS isozymes arose from a duplication of an ancestral gene in the progenote. A further duplication of the entire CPS gene occurred after the divergence of the plants and before the divergence of the fungi from the eukaryotec root, generating the two isoenzymes involved in either the synthesis of arginine or that of pyrimidines. The mutation rate was found to be five- to tenfold higher after the duplication than before, probably reflecting optimization of the enzymes for their newly acquired specialized function. We hypothesize that this duplication arose from a need for metabolic channeling for pyrimidine biosynthesis as it was accompanied by the tagging of the CPS gene with the genes for dihydroorotase and aspartate transcarbamoylase, and as the duplication occurred independently also in gram-positive bacteria. Analysis of the exon-intron organization of the two “kinase” subdomains in CPS I and II suggests that ancient exons may have comprised approx. 19 amino acids, in accordance with the prediction of the “intron-early” theory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173161
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  • 45
    Digitale Medien
    Digitale Medien
    Molecular evolution of genes encoding ribonucleases in ruminant species (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 850-858 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Ribonuclease ; Gene duplication ; Evolution ; Ruminants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Phylogenetic analysis, based on the primary structures of mammalian pancreatic-type ribonucleases, indicated that gene duplication events, which occurred during the evolution of ancestral ruminants, gave rise to the three paralogous enzymes present in the bovine species. Herein we report data that demonstrate the existence of the orthologues of the bovine pancreatic, seminal, and cerebral ribonucleases coding sequences in the genomes of giraffe and sheep. The “seminal” sequence is a pseudogene in both species. We also report an analysis of the transcriptional expression of ribonuclease genes in sheep tissues. The data presented support a model for positive selection acting on the molecular evolution of ruminant ribonuclease genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173164
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  • 46
    Digitale Medien
    Digitale Medien
    Searching tRNA sequences for relatedness to aminoacyl-tRNA synthetase families (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 482-486 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Aminoacyl-tRNA synthetase ; Computer analysis ; Evolution ; Genetic code ; tRNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract tRNA sequences were analyzed for sequence features correlated with known classes of aminoacyl-tRNA synthetase enzymes. The tRNAs were searched for distinguishing nucleotides anywhere in their sequences. The analyses did not find nucleotides predictive of synthetase class membership. We conclude that such nucleotides never existed in tRNA sequences or that they existed and were lost from many of the tRNA sequences during evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166616
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  • 47
    Digitale Medien
    Digitale Medien
    Divergence of glutamate and glutamine aminoacylation pathways: Providing the evolutionary rationale for mischarging (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 476-481 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Aminoacylation ; Aminoacyl-tRNA synthetases ; tRNA ; GluRS ; GlnRS ; Glutamate ; Glutamine ; Evolution ; Mischarging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Aminoacyl-tRNA for protein synthesis is produced through the action of a family of enzymes called aminoacyl-tRNA synthetases. A general rule is that there is one aminoacyl-tRNA synthetase for each of the standard 20 amino acids found in all cells. This is not universal, however, as a majority of prokaryotic organisms and eukaryotic organelles lack the enzyme glutaminyl-tRNA synthetase, which is responsible for forming Gln-tRNAGln in eukaryotes and in Gram-negative eubacteria. Instead, in organisms lacking glutaminyl-tRNA synthetase, Gln-tRNAGln is provided by misacylation of tRNAGln with glutamate by glutamyl-tRNA synthetase, followed by the conversion of tRNA-bound glutamate to glutamine by the enzyme Glu-tRNAGln amidotransferase. The fact that two different pathways exist for charging glutamine tRNA indicates that ancestral prokaryotic and eukaryotic organisms evolved different cellular mechanisms for incorporating glutamine into proteins. Here, we explore the basis for diverging pathways for aminoacylation of glutamine tRNA. We propose that stable retention of glutaminyl-tRNA synthetase in prokaryotic organisms following a horizontal gene transfer event from eukaryotic organisms (Lamour et al. 1994) was dependent on the evolving pool of glutamate and glutamine tRNAs in the organisms that acquired glutaminyl-tRNA synthetase by this mechanism. This model also addresses several unusual aspects of aminoacylation by glutamyl- and glutaminyl-tRNA synthetases that have been observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166615
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  • 48
    Digitale Medien
    Digitale Medien
    Structure, function and evolution of seryl-tRNA synthetases: Implications for the evolution of aminoacyl-tRNA synthetases and the genetic code (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 519-530 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Aminoacyl-tRNA synthetases ; tRNA ; Genetic code ; RNA world ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two aspects of the evolution of aminoacyl-tRNA synthetases are discussed. Firstly, using recent crystal structure information on seryl-tRNA synthetase and its substrate complexes, the coevolution of the mode of recognition between seryl-tRNA synthetase and tRNAser in different organisms is reviewed. Secondly, using sequence alignments and phylogenetic trees, the early evolution of class 2 Amnoacyl-tRNA synthetases is traced. Arguments are presented to suggest that synthetases are not the oldest of protein enzymes, but survived as RNA enzymes during the early period of the evolution of protein catalysts. In this view, the relatedness of the current synthetases, as evidenced by the division into two classes with their associated subclasses, reflects the replacement of RNA synthetases by protein synthetases. This process would have been triggered by the acquisition of tRNA 3′ end charging activity by early proteins capable of activating small molecules (e.g., amino acids) with ATP. If these arguments are correct, the genetic code was essentially frozen before the protein synthetases that we know today came into existence. Correspondence to: S. Cusack
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166620
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  • 49
    Digitale Medien
    Digitale Medien
    Differential homogenization and amplification of two satellite DNAs in the genus Cucurbita (Cucurbitaceae) (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 996-1005 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Repetitive DNA ; Tandem repeats ; Sequence analysis ; Phylogenetic tree ; Silent repeats ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two different satellite DNAs exist in the genus Cucurbita which are different with respect to repeat length (350 by and 170 bp), array size, and sequence homogenization. Whereas the 350-bp satellite DNA is prominent and very homogeneous in all species investigated except for C. maxima and C. lundelliana, the 170-bp satellite is rather evenly distributed in all species. In C. maxima and C. lundelliana the 350-bp satellite is present only in small amounts, but detectable by the sensitive PCR method. These repeats are also very homogeneous, reflecting a silent stage of satellite DNA. In contrast, the 170-bp satellite DNA is intra- and interspecifically heterogeneous. It is striking that the species with no detectable amount of 350-bp satellite contain 170-bp satellite DNA clusters with the highest degree of homogeneity. The evolution of satellite DNA repeats within cultivated and wild species in the genus Cucurbita is elucidated using the sequence data of both satellite DNAs from all species investigated. The value of satellite DNA for phylogenetic analysis between closely related species is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173181
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  • 50
    Digitale Medien
    Digitale Medien
    Simple repetitive DNA sequences from primates: Compilation and analysis (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 120-126 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Simple repetitive DNA ; Microsatellites ; Unstable triplets ; Database ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Simple repeats composed of tandemly repeated units 1–6 nucleotides (nt) long have been extracted from a selected set of primate genomic DNA sequences. Of the 501 theoretically possible, different types of repeats only 67 were present in the analyzed database in at least two different size ranges over 12 nt. They include all simple repeats known to be polymorphic in the primate genome. A list of moderately expanding and nonexpanding oligonucleotide patterns has also been included. Furthermore, we have compiled statistical data with emphasis on the overall variability of the most abundant 67 types of repeats. We have demonstrated that the expandability of at least some simple repeats may be affected by the overall base composition and by flanking sequences. In particular, the occurrence of tandemly repeated CAG and GCC triplets in exons positively correlates with their G+C content. We also noted that in the vicinity of Alu sequences tetrameric repeats are more abundant than in the total genomic DNA. This paper can be used as a comprehensive guide in identification of the most abundant and potentially polymorphic simple repeats. It is also of broader significance as a step toward understanding the contribution of flanking sequences and the overall sequence composition to variability of simple repeats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00167107
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  • 51
    Digitale Medien
    Digitale Medien
    Evolution of seed storage protein genes: Legumin genes of Ginkgo biloba (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 457-466 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Seed storage proteins ; Legumin ; Gene structure ; Evolution ; Gymnosperms ; Ginkgo biloba
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Legumin-like seed storage proteins have been intensively studied in crop plants. However, little is known about the molecular evolution of these proteins and their genes and it was assumed that they originated from an ancestral gene that already existed at the beginning of angiosperm evolution. We have evidence for the ubiquitous occurrence of homologous proteins in gymnosperms as well. We have characterized the major seed storage globulin from Ginkgo biloba by amino acid sequencing, which reveals clear homology to legumin-like proteins from angiosperms. The Ginkgo legumin is encoded by a gene family; we describe two of its members. The promoter regions contain sequence motifs which are known to function as regulatory elements involved in seed-specific expression of angiosperm legumins, although the tissues concerned are different in gymnosperms and angiosperms. The Ginkgo legumin gene structure is divergent from that of angiosperms and suggests that the evolution of legumin genes implicated loss of introns. From our data and from functional approaches recently described it becomes obvious that the posttranslational processing site of legumin precursors is less conserved than hitherto assumed. Finally, we present a phylogenetic analysis of legumin encoding sequences and discuss their utility as molecular markers for the reconstruction of seed plant evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160317
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  • 52
    Digitale Medien
    Digitale Medien
    Polymorphism, monomorphism, and sequences in conserved microsatellites in primate species (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 492-497 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Primate ; Microsatellite ; Evolution ; Mutation process
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Dimeric short tandem repeats are a source of highly polymorphic markers in the mammalian genome. Genetic variation at these hypervariable loci is extensively used for linkage analysis, for the identification of individuals, and may be useful for interpopulation and interspecies studies. In this paper, we analyze the variability and the sequences of a segment including three microsatellites, first described in man, in several species of primates (chimpanzee, orangutan, gibbon, and macaque) using the heterologous primers (man primers). This region is located on the human chromosome 6p, near the tumor necrosis factor genes, in the major histocompatibility complex. The fact that these primers work in all species studied indicates that they are conserved throughout the different lineages of the two superfamilies, the Hominoidea and the Cercopithecidea, represented by the macaques. However, the intervening sequence displays intraspecific and interspecific variability. The sites of base substitutions and the insertion/ deletion events are not evenly distributed within this region. The data suggest that it is necessary to have a minimal number of repeats to increase the rate of mutation sufficiently to allow the development of polymorphism. In some species, the microsatellites present single base variations which reduce the number of contiguous repeats, thus apparently slowing the rate of additional slippage events. Species with such variations or a low number of repeats are monomorphic. These microsatellite sequences are informative in the comparison of closely related species and reflect the phylogeny of the Old World monkeys, apes, and man.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160321
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  • 53
    Digitale Medien
    Digitale Medien
    Phylogenetic relationships of nonaxenic filamentous cyanobacterial strains based on 16S rRNA sequence analysis (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 194-200 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Ribosomal RNA ; Cyanobacteria ; Leptolyngbya ; Oscillatoria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to determine the nearly complete 16S rRNA gene sequences of cyanobacteria originating from nonaxenic cultures, a cyanobacterium-specific oligonucleotide probe was developed to distinguish polymerase chain reaction (PCR) products of the cyanobacterial rRNA operons from those resulting from amplification of contaminating bacteria. Using this screening method the 16S rRNA genes of four nonaxenic filamentous cyanobacterial strains belonging to the generaLeptolyngbya andOscillatoria were cloned and sequenced. For the genusLeptolyngbya, the 16S rRNA sequence of the axenic strain PCC 73110 was also determined. Phylogenetic trees were constructed based on complete and partial sequences. The results show that the strainsLeptolyngbya foveolarum Komárek 1964/112,Leptolyngbya sp. VRUC 135 Albertano 1985/1, andLeptolyngbya boryanum PCC 73110 belong to the same cluster. StrainOscillatoria cf.corallinae SAG 8.92, which contains the rare photosynthetic pigment CU-phycoerythrin, is not closely related to other CU-phycoerythrin-containing cyanobacteria.Oscillatoria agardhii CYA 18, which is a representative of planktonicOscillatoria species that form toxic blooms in Norwegian inland waters, has no close relatives in the tree.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02198845
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  • 54
    Digitale Medien
    Digitale Medien
    Visual pigment diversity in two genera of mantis shrimps implies rapid evolution (Crustacea; Stomatopoda) (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 371-384 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Visual pigment ; Stomatopoda ; Visual ecology ; Evolution ; Photoreceptor ; Retina
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract 1. Interspecific diversity in the visual pigments of stomatopod crustaceans was characterized using microspectrophotometry. We examined the 10 visual pigments in main rhabdoms in retinas of 3 species of each of two genera of stomatopod crustaceans of the superfamily Gonodactyloidea, Gonodactylus (G. oerstedii, G. aloha, and G. curacaoensis) and Odontodactylus (O. scyllarus, O. brevirostris, and O. “havanensis”). Species were selected to provide a matched diversity of habitats. 2. In each genus, visual pigments varied in λmax in several regions of the retina, as revealed by analysis of variance. The variation within closely related species of the same genus implies that visual pigments can evolve rapidly in stomatopods. 3. In photoreceptors of the peripheral retina, which are devoted to spatial vision, visual pigment λmax decreased as the depth range of the various species increased, a typical pattern for marine animals. In contrast, visual pigment λmax in photoreceptors of retinal regions devoted to polarization vision (midband Rows 5 and 6) is not obviously correlated with the spectral environment, implying that polarization information may be confined to particular spectral ranges. Visual pigments of the tiered rows of the midband, which are committed to spectral analysis, span a larger spectral range in shallow-water than deepwater species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00194991
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  • 55
    Digitale Medien
    Digitale Medien
    Olfactory receptors in aquatic and terrestrial vertebrates (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 635-650 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Olfactory receptors ; Multigene families ; Pseudogenes ; Vertebrate species ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In species representing different levels of vertebrate evolution, olfactory receptor genes have been identified by molecular cloning techniques. Comparing the deduced amino-acid sequences revealed that the olfactory receptor gene family of Rana esculenta resembles that of Xenopus laevis, indicating that amphibians in general may comprise two classes of olfactory receptors. Whereas teleost fish, including the goldfish Carassius auratus, possess only class I receptors, the `living fossil' Latimeria chalumnae is endowed with both receptor classes; interestingly, most of the class II genes turned out to be pseudogenes. Exploring receptor genes in aquatic mammals led to the discovery of a large array of only class II receptor genes in the dolphin Stenella Coeruleoalba; however, all of these genes were found to be non-functional pseudogenes. These results support the notion that class I receptors may be specialized for detecting water-soluble odorants and class II receptors for recognizing volatile odorants. Comparing the structural features of both receptor classes from various species revealed that they differ mainly in their extracellular loop 3, which may contribute to ligand specificity. Comparing the number and diversity of olfactory receptor genes in different species provides insight into the origin and the evolution of this unique gene family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050287
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  • 56
    Digitale Medien
    Digitale Medien
    Neural control of the pyloric region in the foregut of the shrimp Penaeus (Decapoda: Penaeidae) (1997)
    Springer
    Journal of comparative physiology 181 (1997), S. 367-382 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Stomatogastric ganglion ; Penaeus ; Pyloric circuit ; Neurotransmitter ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Pyloric pattern-generating neurons that control the pyloric region of the foregut were identified in the stomatogastric ganglion of the most primitive decapod genus Penaeus. Five types of motor neurons and one interneuron are involved in generation of pyloric motor pattern. One cell type of motor neurons innervates muscles of both the gastric mill and the pylorus like the gastric motor neurons in Cancer, but unlike those in Panulirus. These identified neurons are connected to each other either by electrical or inhibitory chemical synapses to construct the neural circuit. This pyloric circuit is similar to the homologous circuit of other crustacean species though some differences are seen in synaptic connections, supporting the hypothesis that the basic design of the neural circuit has been conserved during evolution of the Malacostraca, and that differences have occurred in the synaptic connectivity as the foregut structure has become complex. The motor neurons use either acetylcholine or glutamate as a neurotransmitter like in reptantians. The foregut structure, the number of the pyloric cells, muscle innervation, neurotransmitters, and circuitry are compared among malacostracan crustaceans to provide insight into how the neural circuits change and evolve to produce the motor patterns mediating behaviour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050122
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  • 57
    Digitale Medien
    Digitale Medien
    A nose that looks like a hand and acts like an eye: the unusual mechanosensory system of the star-nosed mole (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 367-372 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Cortical magnification ; Somatosensory cortex ; Development ; Evolution ; Behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The star-nosed mole (Condylura cristata) has a snout surrounded by 22 fleshy and mobile appendages. This unusual structure is not an olfactory organ, as might be assumed from its location, nor is it used to manipulate objects as might be guessed from its appearance. Rather, the star is devoted to the sense of touch, and for this purpose the appendages are covered with thousands of small mechanoreceptive Eimer's organs. Recent behavioral studies find that the star acts much like a tactile eye, having a small behavioral focus, or “fovea” at the center – used for detailed explorations of objects of interest. The peripheral and central nervous systems of the mole reflect these behavioral specializations, such that the small behavioral focus on the nose is more densely innervated in the periphery, and has a greatly enlarged representation in the somatosensory cortex. This somatosensory representation of the tactile fovea is not correlated with anatomical parameters (innervation density) as found in other species, but rather is highly correlated with patterns of behavior. The many surprising parallels between the somatosensory system of the mole, and the visual systems of other mammals, suggest a convergent and perhaps common organization for highly developed sensory systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050396
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  • 58
    Digitale Medien
    Digitale Medien
    Peripheral frequency mis-match in the primitive ensiferan Cyphoderris monstrosa (Orthoptera: Haglidae) (1999)
    Springer
    Journal of comparative physiology 184 (1999), S. 543-551 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Auditory physiology ; Insect ; Frequency discrimination ; Evolution ; Song recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Peripheral auditory frequency tuning in the ensiferan insect Cyphoderris monstrosa (Orthoptera: Haglidae) was examined by comparing tympanal vibrations and primary auditory receptor responses. In this species there is a mis-match between the frequency of maximal auditory sensitivity and the frequency content of the species' acoustic signals. The mis-match is not a function of the mechanical properties of the tympanum, but is evident at the level of primary receptors. There are two classes of primary receptors: low-tuned and broadly tuned. Differences in the absolute sensitivity of the two receptor types at the male song frequency would allow the auditory system to discriminate intraspecific signals from sounds containing lower frequencies. Comparisons of tympanal and receptor tuning indicated that the sensitivity of the broadly tuned receptors did not differ from that of the tympanum, while low-tuned receptors had significantly narrower frequency tuning. The results suggest that the limited specialization for the encoding of intraspecific signals in the auditory system of C. monstrosa is a primitive rather than a degenerate condition. The limited specialization of C. monstrosa may reflect the evolutionary origin of communication-related hearing from a generalized precursor through the addition of peripheral adaptations (tympana, additional receptors) to enhance frequency sensitivity and discrimination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050354
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  • 59
    Digitale Medien
    Digitale Medien
    Comparison of morphology and physiology of two plurisegmental sound-activated interneurones in a bushcricket (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 199-205 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Hearing ; Orthoptera ; Phaneropteridae ; Cercal system ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The unusual morphology of a sound-activated plurisegmental ascending interneurone (AN5-AG7) in an insect (Ancistrura nigrovittata, Ensifera, Phaneropteridae) is described. This neurone's soma is located in the penultimate abdominal ganglion. The most prominent arborisations with smooth endings are found in the prothoracic ganglion. The neurone terminates with numerous beaded endings in the brain (protocerebrum). All abdominal ganglia including the penultimate contain only tiny side branches of beaded appearance. The neurone's morphology is compared to the morphology of a `typical' sound-activated plurisegmental neurone of bushcrickets with its soma in the prothorax. In the prothoracic ganglion and in the brain the arborisations of the two cells are very similar. Graded potentials and action potentials are generated in the prothoracic portion of both neurones. Both receive excitation mainly by ultrasound, and inhibition by soma-ipsilateral stimuli. Neither wind, substrate vibration nor touch of the abdomen evoke responses in AN5-AG7. It is assumed that early in evolution this neurone had its dendrites in the ganglion which houses the cell body (like cercal interneurones of this neuromere). Profound evolutionary changes probably have taken place to bring about this neuron's modern morphology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050378
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  • 60
    Digitale Medien
    Digitale Medien
    Bat-deafness in day-flying moths (Lepidoptera, Notodontidae, Dioptinae) (1997)
    Springer
    Journal of comparative physiology 181 (1997), S. 477-483 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Insects ; Bats ; Ears ; Evolution ; Neotropics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Assuming that bat-detection is the primary function of moth ears, the ears of moths that are no longer exposed to bats should be deaf to echolocation call frequencies. To test this, we compared the auditory threshold curves of 7 species of Venezuelan day-flying moths (Notodontidae: Dioptinae) to those of 12 sympatric species of nocturnal moths (Notodontidae: Dudusinae, Noctuidae and Arctiidae). Whereas 2 dioptines (Josia turgida, Zunacetha annulata) revealed normal ears, 2 (J. radians, J. gopala) had reduced hearing at bat-specific frequencies (20–80 kHz) and the remaining 3 (Thirmida discinota, Polypoetes circumfumata and Xenorma cytheris) revealed pronounced to complete levels of high-frequency deafness. Although the bat-deaf ears of dioptines could function in other purposes (e.g., social communication), the poor sensitivities of these species even at their best frequencies suggest that these moths represent a state of advanced auditory degeneration brought about by their diurnal life history. The phylogeny of the Notodontidae further suggests that this deafness is a derived (apomorphic) condition and not a retention of a primitive (pleisiomorphic), insensitive state.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050131
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  • 61
    Digitale Medien
    Digitale Medien
    Acoustic communication underground: vocalization characteristics in subterranean social mole-rats (Cryptomys sp., Bathyergidae) (1997)
    Springer
    Journal of comparative physiology 180 (1997), S. 245-255 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Mole-rat  ;  Vocalization  ;  Acoustic communication  ;  Subterranean mammal  ; Hearing  ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In captive adult Zambian mole-rats 14 different sounds (13 true vocalizations) have been recorded during different behavioural contexts. The sound analysis revealed that all sounds occurred in a low and middle frequency range with main energy below 10 kHz. The majority of calls contained components of 1.6–2 kHz, 0.63–0.8 kHz, and/or 5–6.3 kHz. The vocalization range thus matched well the hearing range as established in other studies. The frequency content of courtship calls in two species of Zambian Cryptomys was compared with that in naked mole-rats (Heterocephalus glaber) and blind mole-rats (Spalax ehrenbergi) as described in the literature. The frequency range of maximum sound energy is negatively correlated with the body weight and coincides with the frequencies of best hearing in the respective species. In general, the vocalization range in subterranean mammals is shifted towards low frequencies which are best propagated in underground burrows.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050045
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  • 62
    Digitale Medien
    Digitale Medien
    Spatial discrimination of pheromones and behavioural antagonists by the tortricid moths Cydia pomonella and Adoxophyes orana (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 419-425 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key wordsCydia pomonella ; Adoxophyes orana ; Sex pheromone ; Interspecific interruption ; Evolution ; AbbreviationsZ9-14:Ac (Z9)-tetradecenylacetate Z11-14:Ac (Z11)-tetradecenylacetate ; E8, E10-12:OH (E8, E10)-dodecadienol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Male moths responding to their species-specific sex pheromone, may cease their upwind flight when pheromone components of sympatric species are added to the mixture. The interspecific interaction between the pheromone response of the tortricid moths Cydia pomonella and Adoxophyes orana was investigated in field-trapping and wind-tunnel studies. Addition of the A. orana pheromone [(Z9)-tetradecenylacetate and (Z11)-tetradecenylacetate] to a source containing the C. pomonella pheromone [(E8, E10)-dodecadienol] resulted in a significant inhibition of attraction by male C. pomonella. It is demonstrated that this behavioural antagonist for C. pomonella must be emitted from the same point source to induce this inhibitory effect. A spatial separation of the two interspecific pheromones (at 14 cm, 5 cm and 0.5 cm crosswind) restored the attraction of the conspecific pheromone for male C. pomonella. In contrast to C. pomonella, male A. orana were not inhibited by point sources releasing both the C. pomonella and A. orana pheromone. We suggest that the discrepancy in the interspecific pheromone interaction between these two tortricids can be explained if we consider the evolutionary ecology of interspecific pheromone communication in C. pomonella and A. orana.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050402
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  • 63
    Digitale Medien
    Digitale Medien
    Analysis of GC-rich repetitive nucleotide sequences in great apes (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 405-412 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Primate ; Evolution ; Heterochromatin ; Repetitive sequences ; β Satellite sequences ; L1 transposon ; Polymerase chain reaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genomes of four primate species, belonging to the families Pongidae (chimpanzee, gorilla, and orangutan) and Hylobatidae (gibbons), have been analyzed for the presence and organization of two human GC-rich heterochromatic repetitive sequences: βSatellite (βSat) and LongSau (LSau) repeats. By Southern blot hybridization and PCR, both families of repeats were detected in all the analyzed species, thus indicating their origin in an ape ancestor. In the chimpanzee and gorilla, as in man, βSat sequences showed a 68-bp Sau3A periodicity and were preferentially organized in large clusters, whereas in the orangutan, they were organized in DNA fragments of 550 bp, which did not seem to be characterized by a tandem organization. On the contrary, in each of the analyzed species, the bulk of LSau sequences showed a longer Sau3A periodicity than that observed in man (450–550 bp). Furthermore, only in the chimpanzee genome some of LSau repeats seemed to be interspersed within blocks of βSat sequences. This sequence organization, which also characterizes the human genome, is probably absent in the gorilla. In fact, the analysis of a gorilla genomic library suggested that LSau repeats are not preferentially in linkage with βSat sequences. Moreover, LSau sequences were found in a genomic sector characterized by the simultaneous presence of L1 and (CA) repeats, as well as of anonymous sequences and known genes. In spite of the different sequence organization, the nucleotide differences between complete human and gorilla LSau repeats were very few, whereas one gorilla LSau repeat, interrupted by a probably-truncated L1 transposon, showed a higher degree of divergence. Besides the gorilla, this unusual sequence organization was detected in man, and, to a lesser extent, in the chimpanzee.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00164027
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  • 64
    Digitale Medien
    Digitale Medien
    Partial sequence of ribulose-1,5-bisphosphate carboxylase/oxygenase and the phylogeny of Prochloron and Prochlorococcus (Prochlorales) (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 671-677 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Chloroplasts ; Evolution ; Rubisco ; Picoplankton ; Prochloron ; Prochlorothrix ; Prochlorococcus ; Prochlorales
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The prochlorophytes, oxygenic photosynthetic prokaryotes having no phycobiliprotein but possessing chlorophylls a and b, have been proposed to have a common ancestry with green chloroplasts, yet this is still controversal. We report here that partial sequence comparisons of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, including sequence data from two prochlorophytes, Prochlorococcus and Prochloron, indicate that Prochlorococcus is more closely related to a photosynthetic bacterium, Chromatium vinosum (γ-purple bacteria), than to cyanobacteria, while Prochloron is closely related to the prochlorophyte Prochlorothrix and to cyanobacteria. The molecular phylogenetic tree indicates that a common ancestor of Prochlorococcus and γ-purple bacteria branched off from the land plant lineage earlier than Prochloron, Prochlorothrix, and cyanobacteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160516
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  • 65
    Digitale Medien
    Digitale Medien
    Caenorhabditis elegans contains genes encoding two new members of the Zn-containing alcohol dehydrogenase family (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 46-53 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Alcohol dehydrogenase ; Caenorhabditis elegans ; Evolution ; Gene families
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have characterized two cDNA clones from the nematode Caenorhabditis elegans that display similarity to the alcohol dehydrogenase (ADH) gene family. The nucleotide sequences of these cDNAs predict that they encode Zn-containing long-chain ADH enzymes. Phylogenetic analysis suggests that one is most similar to dimeric class III ADHs found in diverse taxa; the other is most similar to the tetrameric forms of ADH previously described only in fungi.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00174040
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  • 66
    Digitale Medien
    Digitale Medien
    Analyses of ribosomal RNA sequences from glaucocystophyte cyanelles provide new insights into the evolutionary relationships of plastids (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 203-210 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Cyanelles ; Cyanophora paradoxa ; Endosymbiosis ; Evolution ; Glaucocystophyta ; Glaucophyta ; Phylogeny ; Plastid ; 16S ribosomal RNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Glaucocystophyte algae (sensu Kies, Berl. Deutsch. Bot. Ges. 92, 1979) contain plastids (cyanelles) that retain the peptidoglycan wall of the putative cyanobacterial endosymbiont; this and other ultrastructural characters (e.g., unstacked thylakoids, phycobilisomes) have suggested that cyanelles are “primitive” plastids that may represent undeveloped associations between heterotrophic “host” cells (i.e., glaucocystophytes) and cyanobacteria. To test the monophyly of glaucocystophyte cyanelles and to determine their evolutionary relationship to other plastids, complete 16S ribosomal RNA sequences were determined for Cyanophora paradoxa, Glaucocystis nostochinearum, Glaucosphaera vacuolata, and Gloeochaete wittrockiana. Plastid rRNAs were analyzed with the maximum-likelihood, maximumparsimony, and neighbor joining methods. The phylogenetic analyses show that the cyanelles of C. paradoxa, G. nostochinearum, and G. wittrockiana form a distinct evolutionary lineage; these cyanelles presumably share a monophyletic origin. The rDNA sequence of G. vacuolata was positioned within the nongreen plastid lineage. This result is consistent with analyses of nuclear-encoded rRNAs that identify G. vacuolata as a rhodophyte and support its removal from the Glaucocystophyta. Results of a global search with the maximumlikelihood method suggest that cyanelles are the first divergence among all plastids; this result is consistent with a single loss of the peptidoglycan wall in plastids after the divergence of the cyanelles. User-defined tree analyses with the maximum-likelihood method indicate, however, that the position of the cyanelles is not stable within the rRNA phylogenies. Both maximumparsimony and neighbor-joining analyses showed a close evolutionary relationship between cyanelles and nongreen plastids; these phylogenetic methods were sensitive to inclusion/exclusion of the G. wittrockiana cyanelle sequence. Base compositional bias within the G. wittrockiana 16S rRNA may explain this result. Taken together the phylogenetic analyses are interpreted as supporting a near-simultaneous radiation of cyanelles and green and nongreen plastids; these organelles are all rooted within the cyanobacteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00170674
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  • 67
    Digitale Medien
    Digitale Medien
    Molecular evolution of maize catalases and their relationship to other eukaryotic and prokaryotic catalases (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 570-579 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Catalase ; Phylogenetic tree,Zea mays L. ; Isozyme ; Antioxidant genes ; Gene Structure ; Oxidative stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have compared the nucleotide and protein sequences of the three maize catalase genes with other plant catalases to reconstruct the evolutionary relationship among these catalases. These sequences were also compared with other eukaryotic and prokaryotic catalases. Phylogenies based on distances and parsimony analysis show that all plant catalases derive from a common ancestral catalase gene and can be divided into three distinct groups. The first, and major, group includes maizeCatl, barleyCat1, riceCatB and most of the dicot catalases. The second group is an apparent dicot-specific catalase group encompassing the tobaccoCat2 and tomatoCat. The third is a monocot-specific catalase class including the maize Cat3, barley Cat2, and riceCatA. The maize Cat2 gene is loosely related to the first group. The distinctive features of monocot-specific catalases are their extreme high codon bias at the third position and low degree of sequence similarity to other plant catalases. Similarities in the intron positions for several plant catalase genes support the conclusion of derivation from a common ancestral gene. The similar intron position between bean catalases and human catalase implies that the animal and plant catalases might have derived from a common progenitor gene sequence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02352287
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  • 68
    Digitale Medien
    Digitale Medien
    Low synonymous site variation at thelacY locus inEscherichia coli suggests the action of positive selection (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 79-84 
    Details
    ISSN: 1432-1432
    Schlagwort(e): LacY ; Lactose permease ; Evolution ; Reduced synonymous polymorphism ; Positive selection ; E. coli
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have determined the nucleotide sequences of sevenlacY alleles isolated from natural isolates ofEscherichia coli. Nucleotide heterozygosity estimates for this locus were compared to those obtained from previous studies of intraspecific variation at chromosomal loci, revealing thatlacY has unusually low synonymous site variation. The average pairwise heterozygosity of synonymous sites (Ks=0.0112+/-0.0100) is the second lowest reported and the lowest for loci that have an equivalent level of nonsynonymous variation. We consider several hypotheses to explain how different forces in evolution could act to create the observed pattern of polymorphism, including selection for translational efficiency and positive selection. Our analysis most strongly supports the hypothesis that positive selection has acted on thelacY locus inE. coli.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02198831
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  • 69
    Digitale Medien
    Digitale Medien
    Replacement of nucleosomal histones by histone H1-like proteins during spermiogenesis in Cnidaria: Evolutionary implications (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 240-246 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Sperm nuclear basic proteins (SNBPs) ; Histone H1 ; Cnidaria ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have analyzed the chromosomal protein composition of the sperm from several species belonging to three different classes (Hydrozoa, Scyphozoa, Anthozoa) of the phylum Cnidaria. In every instance, the sperm nuclear basic proteins (SNBPs) were found to consist of one to two major protein fractions that belong to the histone H1 family, as can be deduced from their amino acid composition and solubility in dilute perchloric acid, and the presence of a trypsin-resistant core. In those species where mature spawned sperm could be obtained, we were able to show that these proteins completely replace the somatic histones from the stem cells that are present at the onset of spermatogenesis. The presence of a highly specialized histone H1 molecule in the sperm of this phylum provides support for the idea that the protamine-like proteins (PL) from higher groups in the phylogenetic tree (and possibly protamines as well) may all have evolved from a primitive histone H1 ancestor.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02198850
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  • 70
    Digitale Medien
    Digitale Medien
    Relationships between transposable elements based upon the integrase-transposase domains: Is there a common ancestor? (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 359-368 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Transposable elements ; Evolution ; Horizontal transfers and alternative hypotheses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The integrase domain of RNA-mediated elements (class I) and the transposase domain of DNA-mediated transposable elements (class II) were compared. A number of elements contain the DDE signature, which plays an important role in their integration. The possible relationships betweenmariner-Tc1 andIS elements, retrotransposons, and retroviruses were analyzed from an alignment of this region. Themariner-Tc1 superfamily, and LTR retrotransposons and retroviruses were found to be monophyletic groups. However, theIS elements of bacteria were found in several groups. These results were used to propose an evolutionary history that suggests a common ancestor for some integrases and transposases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02337546
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  • 71
    Digitale Medien
    Digitale Medien
    Lipaemia and liver composition in pregnant rats consuming olive oil and olive oil used for frying (1997)
    Springer
    European journal of nutrition 36 (1997), S. 205-213 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Frying ; growth ; liver lipids ; lipaemia ; olive oil ; pregnancy ; rat ; Fritierung ; Wachstum ; Leberfett ; Olivenöl ; Schwangerschaft ; Ratte
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Um Informartionen über den Zusammenhang zwischen der Aufnahme von Fett, das zum Fritieren benutzt wurde, und dem Fetthaushalt während Perioden starken Körperaufbaus zu haben, wurde der Einfluß der Aufnahme von frischem Olivenöl (Gehalt polarer Verbindungen, 2 %; Ölsäure 78,9 mg/100 mg Öl, und Linolsäure 7 mg/100 mg Öl) und von Olivenöl, das 15 mal in Folge für das Fritieren von Kartoffeln benutzt worden war (Gehalt polarer Verbindungen 9 %; Ölsäure 75,8 mg/100mg Öl und Linolsäure 6,2 mg/100mg Öl) während der Gravidität, untersucht. Dazu wurden trächtige Wistar Ratten in zwei Gruppen geteilt, die beide eine isokalorische Diät bekamen, deren Fettanteil 15 % von frischem (unbenutztem) (P1) bzw. fritiertem (benutztem) (P2) Olivenöl stammte mit nicht trächtigen Ratten verglichen. Die Gravidität erhöhte (p〈0,01) die Futteraufnahme, das Körpergewicht, die Gewichtszunahmen und die Futterverwertung. Die Ölqualität beeinflußte dagegen diese Parameter nicht. Während der Gravidität stiegen die Serumwerte der Triglyceride (TG) (p〈0,01) und des Cholesterins (TC) (p〈0,05) an, während die der Phosphatide (PH) sanken (p〈0,01). Ein signifikanter Effekt der Ölqualität und eine Wechselwirkung zwischen Gravidität und Öl wurde für TG und PH festgestellt. Das Gewicht und der Fettgehalt der Leber der trächtigen Ratten stiegen signifikant an (p.〈0.05), Leber TC, TG und PH stiegen während der Gravidität (ungefähr um das 3-fache der Ausgangswerte), aber es traten keine signifikanten Unterschiede zwischen der Aufnahme von benutztem und nicht benutztem Öl (P2 vs P1) auf. Die Ergebnisse zeigen, daß die Aufnahme von leicht verdorbenem Olivenöl als alleinige Fettquelle der Nahrung keine besonderen Folgen für die Gravidität hat, was die Gewichtszunahme der Mütter und der Feten, die Lipämie und die Zusammensetzung des Leberfetts betrifft.
    Notizen: Summary The effect of the consumption of unused olive oil (polar content, 2 %; oleic acid, 78.9 mg/100 mg oil, and linoleic acid 7 mg/100 mg oil) and olive oil used discontinuously for frying potatoes 15 times (polar content, 9 %; oleic acid, 75.8 mg/100 mg oil and linoleic acid 6.2 mg/100 mg oil) was studied in pregnant rats with the aim of better understanding the relationship between the consumption of fat used in frying and lipid metabolism during periods of intense anabolism. Trials were performed in pregnant Wistar rats, divided into 2 groups and fed isocaloric diets in which the fat content (15 % wt/wt) consisted of unused olive oil (P1) or oil previously used for frying (P2), and the results were compared with those of nonpregnant rats fed unused olive oil (NP1) and olive oil used for frying (NP2). Pregnancy increased (p〈0.01) food intake, body weight, weight gain, and food efficiency ratio (P2 vs NP2 and P1 vs NP1, respectively), but the treatment of oil included in the diets did not alter these parameters. Gestation significantly increased the serum triglyceride (TG) (p〈0.01) and total cholesterol (TC) (p〈0.05) concentrations and diminished that of phospholipids (PH) (p〈0.01). A significant effect of the type of oil consumed and a pregnancy x oil interaction on Tg and PH levels was observed. The weight of the liver and its fat content increased significantly (p〈0.05) as a result of pregnancy. Liver TC, TG, and PH increased (approximately 3 times the original values) during gestation, but no significant differences due to the intake of used or unused oil (P2 vs P1) were observed. The results indicate that the consumption of moderately altered olive oil, as the sole source of fat, does not alter the effect of pregnancy on the mothers' weight gain, lipaemia, and hepatic fat composition to any important degree.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01623365
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  • 72
    Digitale Medien
    Digitale Medien
    Effects of porcine somatotropin on the chemical body composition and fat quality in growing-finishing pigs (1997)
    Springer
    European journal of nutrition 36 (1997), S. 294-298 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Body composition ; fat ; growth ; somatotropin ; pig ; Körperzusammensetzung ; Fett ; Wachstum ; Somatotropin -Schwein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An 78 männlichen Kastraten und weiblichen Schweinen der Kreuzung Pietrain x (Deutsches Edelschwein x Deutsche Landrasse) wurden Untersuchungen zum Einfluß einer porcinen Somatotropin (pST)-Behandlung während des Wachstums auf die chemische Körperzusammensetzung der Tiere, das Adipozyten-Wachstum und das Fettsäure-Profil des Rückenspecks untersucht. Die intramuskulären Injektionen (1 oder 3 mg pST) wurden täglich ab durchschnittlich 65 kg Lebendgewicht bis zum Schlachten verabreicht. Nach der pST-Behandlung wurden bei den Kastraten in allen untersuchten Merkmalen signifikante Unterschiede festgestellt, während sich bei den weiblichen Tieren nur leichte Reaktionen zeigten. Das pST verursachte eine Zunahme des Wasserund Proteingehaltes bei gleichzeitiger Reduzierung des Lipidgehaltes besonders in den fettreichen Körperteilen der Tiere. Im Rückenspeck war der Gehalt an ungesättigten Fettsäuren erhöht und der Fettzelldurchmesser erniedrigt.
    Notizen: Summary Seventy eight growing-finishing pigs (male castrates and females) of the cross-breed Pietrain x (Large White x German Landrace) were used to investigate the effects of pST treatment on the chemical composition of the body, the growth of adipocytes, and the fatty acid profile of the backfat. Intramuscular injections (1 or 3 mg pST) were administered daily from an average weight of 65 kg up to slaughter. After pST treatment significant changes in all studied characteristics were observed in barrows, whereas the females exhibited very small responses. The pST caused an increase of water and protein contents and a simultaneous decrease of lipid content especially in body parts rich in fat. Furthermore, the proportion of unsaturated fatty acids increased and the fat cell diameter decreased in the backfat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01617801
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  • 73
    Digitale Medien
    Digitale Medien
    Localized folding of viscoelastic layers (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 58-64 
    Details
    ISSN: 1437-3262
    Schlagwort(e): Aperiodicity ; Buckling ; Evolution ; Modelling ; Spatial chaos
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Naturally occurring fold systems are typically irregular. Although such systems may sometimes be approximated by a periodic geometry, in reality they are commonly aperiodic. Ord (1994) has proposed that naturally occurring fold systems may display spatial chaos in their geometry. Previous work has indicated that linear theories for the formation of fold systems, such as those developed by Biot (1965), result in strictly periodic geometries. In this paper the development of spatially chaotic geometries is explored for a thin compressed elastic layer embedded in a viscoelastic medium which shows elastic softening. In particular, it is shown that spatially localized forms of buckling can develop and the evolution of these systems in the time domain is presented. A nonlinear partial differential equation, fourth order in a spatial variable and first order in time, is found to govern the evolution. A related nonlinear fourth-order ordinary differential equation governs an initial elastic phase of folding. The latter equation belongs to a class with spatially chaotic solutions. The paper reviews the implications of localization in the geological framework, and draws some tentative conclusions about the development of spatial chaos. Crudely arrived-at, yet plausible, evolutionary time plots under the constraint of constant applied end displacement are presented. Emphasis throughout is on phenomenology, rather than underlying mathematics or numerics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192061
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  • 74
    Digitale Medien
    Digitale Medien
    A Modular Vector for Agrobacterium Mediated Transformation of Wheat (1999)
    Springer
    Plant molecular biology reporter 17 (1999), S. 323-331 
    Details
    ISSN: 1572-9818
    Schlagwort(e): Agrobacterium ; modular vector ; transformation ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007686408369
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  • 75
    Digitale Medien
    Digitale Medien
    Sources of Sectoral Growth in an Economy Wide Context: The Case of U.S. Agriculture (1997)
    Springer
    Journal of productivity analysis 8 (1997), S. 293-310 
    Details
    ISSN: 1573-0441
    Schlagwort(e): growth ; USagriculture ; externalities ; spill-overs ; public R and D
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract Growth in U.S. agriculture is linked to the non-farm economy through domestic terms of trade and factor market adjustments. With almost stable input growth, the relatively large contributions from growth in Total Factor Productivity (TFP) are passed on to intermediate and final consumers in the form of declining real prices for primary farm products. The resulting net growth in the real value of farm output (GDP) is relatively low (0.25% per annum). The decomposition of TFP suggests that public agricultural stock of knowledge and infrastructure are “robustly” associated with TFP growth, while spill-overs from private agricultural and economy wide research and development (R and D) are positive but, relatively small.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007759705652
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  • 76
    Digitale Medien
    Digitale Medien
    A survey on the occurrence of mycotoxins in wheat and maize from western Romania (1998)
    Springer
    Mycopathologia 143 (1998), S. 97-103 
    Details
    ISSN: 1573-0832
    Schlagwort(e): deoxynivalenol ; enzyme immunoassay ; feed ; maize ; mycotoxins ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Samples of wheat (n = 25) and maize (n = 30) for animal consumption, collected in 1997 after harvest from western Romania, were analyzed by enzyme immunoassays for mycotoxin contamination. Toxins analyses included deoxynivalenol (DON), 3-acetylDON, 15- acetylDON, fusarenone X (FX), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), zearalenone (ZEA), fumonisin B1 (FB1), aflatoxin B1 (AFB1), ochratoxin A (OA), and citrinin (CT). DON and acetylDONs were the major contaminants in wheat (100%) and maize (46%). Median values for DON, 3-acetylDON, and 15-acetylDON were 880 μg kg-1, 66 μg kg- 1, and 150 μg kg-1 in wheat, and 890 μg kg-1, 180 μg kg-1, and 620 μg kg- 1 in maize, respectively. Additionally, 3,15-diacetylDON was detected in some samples by HPLC-EIA analysis. All samples were negative for FX (〈150 μg kg-1). T-2 was found in wheat (n = 6) and maize (n = 1) at levels between 13 and 63 μg kg- 1. DAS (2.6 μg kg-1) was found in one maize sample. ZEA occurred in all wheat and in four maize samples, median values were 10 μg kg-1 and 250 μg kg-1, respectively. One maize sample contained FB1 (140 μg kg-1). All samples were AFB1-negative (〈4 μg kg-1). OA was found in one wheat sample (37 μg kg- 1), CT was found in one maize sample (580 μg kg- 1). This first reported natural occurrence of a range of mycotoxins in Romanian feeding stuff shows that DON and acetyl DONs may be present at levels which may affect animal production.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006987205986
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  • 77
    Digitale Medien
    Digitale Medien
    First survey on the natural occurrence of Fusarium mycotoxins in Bulgarian wheat (1996)
    Springer
    Mycopathologia 136 (1996), S. 47-52 
    Details
    ISSN: 1573-0832
    Schlagwort(e): Fusarium ; mycotoxins ; occurrence ; trichothecenes ; wheat ; zearalenone ; deoxynivalenol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Wheat for human consumption (140 samples) was collected after harvest from all regions of Bulgaria. The 1995 crop year was characterized by heavy rainfall in the spring and summer months. The internal mycoflora of wheat samples was dominated by Fusarium spp. and Alternaria spp., and storage fungi were rarely present. The samples were analysed for contamination with Fusarium mycotoxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), and zearalenone (ZEA), using enzyme immunoassay methods. DON and ZEA were the predominant toxins, with a contamination frequency of 67% and 69%, respectively. The average levels of these toxins in positive samples were 180 μg/kg (DON) and 17 μg/kg (ZEA), maximum concentrations were 1800 μg kg−1 and 120 μg kg−1, respectively. Acetyl derivatives of DON, namely 3-AcDON and 15-AcDON, were found in 2.1 % and 0.7% of the samples, at at maximum level of about 100 μg kg−1. Only one sample was positive for T-2 (55 μg/kg), DAS was not detected. This is the first report about the natural occurrence of a range of Fusarium mycotoxins in wheat for human consumption in Bulgaria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00436660
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  • 78
    Digitale Medien
    Digitale Medien
    Estimation of the contribution of biological N2 fixation to twoPhaseolus vulgaris genotypes using simulation of plant nitrogen uptake from15N-labelled soil (1995)
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 169-185 
    Details
    ISSN: 1573-0867
    Schlagwort(e): 15N ; non-nod beans ; quantification of N2 fixation ; reference crops ; simulation technique ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A technique for the application of the15N isotope dilution technique for the quantification of plant associated biological nitrogen fixation (BNF) was tested and applied to quantify the BNF contribution to two genotypes ofPhaseolus vulgaris. The technique makes use of sequential measurements of the15N enrichment of soil mineral N, and the uptake of labelled N by the “N2-fixing” plant, to simulate its uptake of soil N (the “soil to plant simulation” technique). The test was made with two non-N2-fixing crops (non-nodulating beans and wheat) and two bean genotypes (PR 923450 and Puebla 152), at two levels of N fertilizer addition (10 and 40 kg N ha−1), to compare the actual N uptake with that simulated from the soil and crop15N data. The simulation of the soil N uptake by the non-nod bean crop using this “soil to plant simulation” technique underestimated by 20 to 30% the true N uptake, suggesting that the mineral N extracted from soil samples taken from the 0–15cm layer had a higher15N enrichment than that N sampled by the roots of this crop. In the case of the wheat crop the simulation resulted in a much greater underestimation of actual N uptake. In general the results using this technique suggested that BNF inputs to the bean cultivars was higher than would be expected from the nodulation and acetylene reduction data, except for the early PR beans in the 40 kg N ha−1 treatment. In this case the total N and simulated soil N accumulation were well matched suggesting no BNF inputs. An allied technique (the “plant to plant simulation technique”) was proposed where the15N enrichrnent of soil mineral N was simulated from the data for total N and labelled N accumulation taken from sequential harvests of either of the non-N2 -fixing control crops. This was then utilized in combination with the labelled N uptake data of the other crop to simulate its soil N uptake. However, the results using either technique indicated that the wheat and non-nod or nodulating beans exploited pools of N in the soil with completely different15N enrichments probably due to differences in exploitation of the soil N with depth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00748587
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  • 79
    Digitale Medien
    Digitale Medien
    Effect of climate on the recovery in crop and soil of15N-labelled fertilizer applied to wheat (1995)
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 209-215 
    Details
    ISSN: 1573-0867
    Schlagwort(e): climate ; fertilizer recovery ; 15N fertilizer ; precipitation-evaporation quotient ; soil ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Data was assembled from experiments on the fate of15N-labelled fertilizer applied to wheat (Triticum spp.) grown in different parts of the world. These data were then ranked according to the annual precipitation-evaporation quotient for each experimental location calculated from the average long-term values of precipitation and potential evaporation. Percentage recovery of15N fertilizer in crop and soil varied with location in accordance with the precipitation-evaporation quotient. In humid environments more15N fertilizer was recovered in the crop than in the soil, while in dry environments more15N fertilizer was recovered in the soil than in the crop. Irrespective of climatic differences between locations 20% (on average) of the15N fertilizer applied to wheat crops was unaccounted for at harvest. Most of the15N fertilizer remaining in the soil was found in the 0–30 cm layer. The most likely explanation of these differences is that wheat grown in dry environments has a greater root:shoot ratio than wheat grown in humid environments and, further, that the residue of dryland crops have higher C/N ratios. Both factors could contribute to the greater recovery of15N fertilizer in the soil in dry environments than in humid ones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00748591
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  • 80
    Digitale Medien
    Digitale Medien
    Sustainable yield trends of irrigated maize and wheat in a long-term experiment on a loamy sand in semi-arid India (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 225-234 
    Details
    ISSN: 1573-0867
    Schlagwort(e): long-term experiment ; maize ; wheat ; fertilizers ; farm yard manure ; weedicide application ; yield sustainability ; zinc deficiency ; nutrient uptake ; cropping sequence ; organic carbon build-up
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Long-term field experiments play an important role in understanding the complex interactions of plants, soils, climate and management and their effects on sustainable crop production. A long-term fertilizer experiment with maize-wheat-cowpea (fodder) is in progress since 1971 at Punjab Agricultural University farm Ludhiana, India. The experimental result for the first 21 years showed that application of N alone or in combination with P did not produce as much maize and wheat grains as the application of N, P and K together. Eight years after the start of the experiment, the optimal levels of N, P and K application (100% NPK) were unable to sustain the similar (maize) yield level as before because of Zn deficiency. Whereas in FYM amended plots the Zn deficiency did not appear and the higher crop yields could be sustained. The chemical control of weeds could not sustain the maize productivity at the same level as the manual removal of weeds. It was concluded that the high level of crop production can be sustained with the application of N, P and K under intensive cropping system provided deficiency of any of the micronutrient does not crop up. The deficiency of Zn is most likely to occur in semi-arid light textured alluvial soils under intensive cropping without the addition of farm yard manure/organic manures. In maize based cropping systems, manual control of weeds may be preferred to the chemical one. Addition of FYM in conjunction with 100% NPK is most beneficial both from bio-physical and economic point of view.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00420557
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  • 81
    Digitale Medien
    Digitale Medien
    Nitrogen, phosphorus and potassium relations in five major cereals reviewed in respect to fertilizer recommendations using simulation modelling (1995)
    Springer
    Nutrient cycling in agroecosystems 44 (1995), S. 37-49 
    Details
    ISSN: 1573-0867
    Schlagwort(e): millet ; sorghum ; rice ; maize ; wheat ; nutrient harvest index ; post-anthesis nutrient uptake ; recovery fraction ; simulation modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In land use plans, fertilizer recommendations are indispensable to avoid soil nutrient depletion or soil water pollution. Nutrient relations of five cereals have been evaluated on the basis of a literature review with the aim of arriving at such fertilizer recommendations at regional level. Nutrients considered were nitrogen, phosphorus and potassium for millet, sorghum, maize, rice and wheat. The relevant nutrient relations are fertilizer nutrient application to nutrient uptake, and nutrient uptake to crop yield. In addition, post-anthesis nutrient uptake is considered. Subsequently, obtained results are used in simulation modelling exercises to calculate the time required to attain an equilibrium nutrient balance and to investigate the effect of erosion control and straw recycling. Although fertilizer requirements could be assessed for each of the five cereals, monitoring of nutrient supply from natural sources remains necessary. Moreover, research on fertilizer use should focus on improvement of fertilizer recoveries and multiperiod models for both N and P uptakes by crops to allow quantitative land use planning where the time scale is included.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750691
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  • 82
    Digitale Medien
    Digitale Medien
    The effect of foliar supplements of potassium nitrate and urea on the yield of winter wheat (1995)
    Springer
    Nutrient cycling in agroecosystems 44 (1995), S. 217-223 
    Details
    ISSN: 1573-0867
    Schlagwort(e): foliar fertilizer ; nitrate ; potassium ; urea ; wheat ; yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Winter wheat crops were grown with ostensibly adequate supplies of all soil nutrients in 1990 and 1991 with the aim of testing if late foliar supplements of K and N, applied at key development stages, could improve grain yield and grain N content. Foliar sprays of KNO3 solution, supplying up to 40 kg K ha−1 in total, at flag leaf unfolded, inflorescence completed and the watery-ripe stage of grain filling, had no effect on yield, yield components or grain N. Urea, supplying 40 kg N ha−1 at flag leaf unfolded, had no effects on grain yield and grain N in 1990, but in 1991 grain N was increased by 0.14% whilst yield was reduced by up to 0.6 t ha−1. Urea scorched flag leaf tips in both years. In 1990, the spring was very dry and foliar supplements might have been expected to have had an effect, but on this highly fertile soil all crop K and N requirements were met from the soil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750928
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  • 83
    Digitale Medien
    Digitale Medien
    Evaluation of soil extractants for Mn availability and response of wheat to applied Mn in soils of semi-arid zone of Punjab, India (1999)
    Springer
    Nutrient cycling in agroecosystems 53 (1999), S. 139-146 
    Details
    ISSN: 1573-0867
    Schlagwort(e): critical levels of Mn ; soil extractants ; Mn-deficiency ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Seven chemical extractants were tested for their relative performance to predict the response of wheat to Mn application in coarse textured alkaline soils of semi-arid region. Five out of the seven extractants were found to be promising for the estimation of critical level of available Mn in these soils, as the amount of Mn extracted by these extractants was positively and significantly correlated with relative grain yield as well as Mn uptake. The critical deficiency level of soil available Mn with 0.005 M DTPA, 0.02% hydroquinone, 0.02 N sodium pyrophosphate, 0.1N H3PO4 and 0.05N HCl+0.025N H2SO4 was 3.1, 13.8, 23.5, 5.3 and 17.8 mg kg-1 soil, respectively. The 1N ammonium acetate and 0.01M CaCl2 were found to be unsuitable extractants for these soils. Further field trials at eight locations with varying levels of Mn deficiency showed successive increase in the grain yield of wheat with foliar Mn application, emphasizing the need for Mn fertilization when wheat is grown on Mn deficient soils.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009754724227
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  • 84
    Digitale Medien
    Digitale Medien
    Origin and thermal evolution of icy satellites (1995)
    Springer
    Surveys in geophysics 16 (1995), S. 533-591 
    Details
    ISSN: 1573-0956
    Schlagwort(e): Satellites ; Giant planets ; Origin ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The paper reviews the problem of formation and evolution of the so-called “regular satellites “ of the giant planets, and it consists of two parts: the first describes the possible origin of the satellites, the second studies their evolution, attempting to stress the relations of the present status of the satellites with their evolutionary history. The formation of regular satellite systems around giant planets is probably related to the formation of the central planet. Some characteristics of regular satellite systems are quite similar, and suggest a common origin in a disk present around the central body. This disk can originate through different mechanisms which we will describe, paying attention to the so-called “accretion disk” model, in which the satellite-forming material is captured. The disk phase links the formation of the primary body with the formation of satellites. The subsequent stages of the disk's evolution can lead first to the formation of intermediate size bodies, and through the collisional evolution of these bodies, to the birth of satellite “embryos” able to gravitationally capture smaller bodies. Given the scenario in which icy satellites may be formed by homogeneous accretion of planetesimals made of a mixtures of ice and silicates, if no melting occurs during accretion, the satellites have a homogeneous ice-rock composition. For the smaller satellites this homogeneous structure should not be substantially modified; only sporadic local events, such as large impacts, can modify the surface structure of the smaller satellites. For the larger satellites, if some degree of melting appears during accretion, a differentiation of the silicate part occurs, the amount of differentiation and hence the core size depending on the fraction of gravitational potential energy retained during the accumulation process. Melting and differentiation soon after the accretion, for the larger satellites, could also depend on the convective evolution in presence of phase transitions and generate an intermediate rock layer, considerably denser than the underlying, still homogeneous core, and unstable to overturning on a geologic time scale. Moreover the liquid water mantle could be a transient feature because the mantle would freeze over several hundred million years. For these large bodies the stable configuration is expected to be one consisting of a silicate core and a mantle of mixed rock and ice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00665684
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  • 85
    Digitale Medien
    Digitale Medien
    Selenium concentration in spring wheat as influenced by basal application and top dressing of selenium-enriched fertilizers (1995)
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 163-167 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Basal dressing ; Se-enriched fertilizers ; Se-uptake ; soil texture ; top-dressing ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A multisite field experiment was conducted to study the effect of topdressed Se-enriched Ca(NO3)2 (CN) and basal applied NPK on the selenium (Se) concentration in spring wheat (Triticum aestivum L.). Selenium was applied either through CN (at the rates of 0, 6.45, and 12.91 g Se ha−1) or NPK (5.83 g Se ha−1). Selenium concentration in wheat grains increased consistently with increasing rate of Se-enriched CN or NPK. However, the superiority of Se-enriched CN over NPK in raising the Se concentration in wheat grain depended on location and growth conditions. At the same rate both methods of Se-application were found to be equally effective in raising the Se concentration of wheat grains. The Se concentration of grain was generally higher in the light textured soils than in the medium to heavy textured soils. Without Se application, the Se-concentration in wheat grain was about 16µg kg−1 which is regarded insufficient to meet the Se requirement for Se in animal and human. Calcium nitrate enriched with 25 mg Se kg−1 (6.45 g Se ha−1) increased the Se concentration in wheat grain to a desired level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00790666
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  • 86
    Digitale Medien
    Digitale Medien
    Use of a lux-based procedure to rapidly visualize root colonisation by Pseudomonas fluorescens in the wheat rhizosphere (1997)
    Springer
    Antonie van Leeuwenhoek 72 (1997), S. 365-372 
    Details
    ISSN: 1572-9699
    Schlagwort(e): bioluminescence ; Pseudomonas ; root colonization ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The bioluminescently marked Pseudomonas fluorescens strain 5RL, has been used previously to follow colonisation of soy bean roots (De Weger et al. [1991] Appl. Environ. Microbiol. 57:36-41). In the present paper the method has been further developed and optimized for wheat roots and it is used to get a quick overview of the colonisation patterns of many different root systems at the same time. Colonisation was followed on wheat plants grown in our gnotobiotic sand system (Simons et al., 1996. Mol Plant Microbe Interact 9: 600–607) and the following results were obtained. (i) A spatio-temporal analysis of the colonisation of wheat roots showed that 4 days after planting the highest bacterial activity was observed at the upper part of the root. After 6 days the high bacterial activity at the upper part was further increased, whereas spot-like activities were observed on the lower root parts, possibly due to micro-colonies. (ii) Bacterial mutations causing lack of motility or auxotrophy for amino acids resulted in impaired colonisation of the lower root parts, indicating that motility and prototrophy for the involved amino acid(s) are important factors for wheat root colonisation by strain 5RL. (iii) Coinoculation of strain 5RL with other wild type Pseudomonas strains on the root influenced the colonisation pattern observed for strain 5RL. Colonisation was not visually affected when the competing strain was a poor root coloniser, but was severely reduced when the competing strain was a good root coloniser. The results show that the spatio-temporal colonisation of wheat root by P. fluorescens strain 5RL and derivatives is similar to that of strain WCS365 on tomato. The advantage of the use of lux-marked strains is that the results are obtained much quicker than when conventional methods are used and that the result is supplied as an image of the colonisation pattern of many different roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000565413024
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  • 87
    Digitale Medien
    Digitale Medien
    Evolution on a Smooth Landscape: The Role of Bias (1998)
    Springer
    Journal of statistical physics 90 (1998), S. 191-210 
    Details
    ISSN: 1572-9613
    Schlagwort(e): Evolution ; birth/death processes ; mean-field ; population dynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The role of mutational bias in evolution on a smooth landscape is investigated. We consider both a finite-length genome where the bias increases linearly with the fitness, and an infinite genome with a fixed bias. We present simulations of finite populations in a waiting time model, showing both the nonequilibrium dynamics and the equilibrium fitness distributions that are reached. We compute the equilibrium analytically in several cases, using approximate direct solution of the master equations and truncated hierarchies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1023203818384
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  • 88
    Digitale Medien
    Digitale Medien
    Influence of within-field and landscape factors on aphid predator populations in wheat (1999)
    Springer
    Landscape ecology 14 (1999), S. 239-252 
    Details
    ISSN: 1572-9761
    Schlagwort(e): Coccinellidae ; Aphididae ; wheat ; spatial scale ; species diversity ; numerical response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The influence of prey density, within-field vegetation, and the composition and patchiness of the surrounding landscape on the abundance of insect predators of cereal aphids was studied in wheat fields in eastern South Dakota, USA. Cereal aphids, aphid predators, and within-field vegetation were sampled in 104 fields over a three year period (1988–1990). The composition and patchiness of the landscape surrounding each field were determined from high altitude aerial photographs. Five landscape variables, aggregated at three spatial scales ranging from 2.6 km2 to 581 km2, were measured from aerial photographs. Regression models incorporating within-field and landscape variables accounted for 27–49% of the variance in aphid predator abundance in wheat fields. Aphid predator species richness and species diversity were also related to within-field and landscape variables. Some predators were strongly influenced by variability in the composition and patchiness of the landscape surrounding a field at a particular spatial scale while others responded to variability at all scales. Overall, predator abundance, species richness, and species diversity increased with increasing vegetational diversity in wheat fields and with increasing amounts of non-cultivated lands and increasing patchiness in the surrounding landscape.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008002528345
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  • 89
    Digitale Medien
    Digitale Medien
    Management of Stored Wheat Insect Pests in the USA (1999)
    Springer
    Integrated pest management reviews 4 (1999), S. 127-143 
    Details
    ISSN: 1572-9745
    Schlagwort(e): wheat ; stored-grain ; integrated pest management ; aeration ; biological control ; grain sampling ; insect monitoring ; modeling ; area-wide IPM
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Management of stored-grain insect pests by farmers or elevator managers should be based upon a knowledge of the grain storage environment and the ecology of insect pests. Grain storage facilities and practices, geographical location, government policies, and marketing demands for grain quality are discussed as factors influencing stored-grain insect pest management decisions in the United States. Typical practices include a small number of grain samples designed to provide grain quality information for segregation, blending and marketing. This low sampling rate results in subjective evaluation and inconsistent penalties for insect-related quality factors. Information on the efficacy of insect pest management practices in the United States, mainly for farm-stored wheat, is discussed, and stored-grain integrated pest management (IPM) is compared to field-crop IPM. The transition from traditional stored-grain insect pest control to IPM will require greater emphasis on sampling to estimate insect densities, the development of sound economic thresholds and decision-making strategies, more selective use of pesticides, and greater use of nonchemical methods such as aeration. New developments in insect monitoring, predictive computer models, grain cooling by aeration, biological control, and fumigation are reviewed, their potential for improving insect pest management is discussed, and future research needs are examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009682410810
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  • 90
    Digitale Medien
    Digitale Medien
    The determination of the age and growth of SE Asian mangrove seedlings from internodal counts (1999)
    Springer
    Mangroves and salt marshes 3 (1999), S. 251-257 
    Details
    ISSN: 1572-977X
    Schlagwort(e): Avicennia alba ; growth ; internodal sequences ; mangrove age determination ; Rhizophora apiculata ; Sonneratia caseolaris ; Thailand
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The occurrence of periodic changes in the length of the internodes of the seedlings of SE Asian mangrove species (Rhizophora apiculata, Avicennia alba, and Sonneratia caseolaris) growing in the Pak Phanang estuary (Nakhon Si Thammarat, SE Thailand) was confirmed. The annual nature of these periodic changes was verified through comparisons with the observed average number of internodes produced by plants tagged for one year. The cycles in the sequence of internodal length of the seedlings had an average (± SE) period of 16.0 ± 0.78 internodes for Avicennia alba, 25.0 ± 1.2 internodes for Sonneratia caseolaris, and 8.29 ± 0.40 internodes for Rhizophora apiculata. These values are remarkably close to, and not significantly different (t‐test, P 〉 0.05) from the average (± SE) annual number of internodes of 17.6 ± 0.8 for Avicennia alba, 28.8 ± 2.1 for Sonneratia caseolaris, and 8.03 ± 0.36 for Rhizophora apiculata produced in a year by tagged plants. In addition, the average (± SE) growth of the tagged plants was 0.39 ± 0.018 cm day-1 for Avicennia alba, 0.24 ± 0.015 cm day-1 for Sonneratia caseolaris, and 0.091 ± 0.0036 cm day-1 for Rhizophora apiculata. These estimates were very close to those (0.45 ± 0.06 cm day-1 for Avicennia alba, 0.32 ± 0.01 cm day-1 for Sonneratia caseolaris, and 0.13 ± 0.005 cm day-1 for Rhizophora apiculata) derived as the product of the mean number of internodes produced per day, calculated from the inferred number of internodes produced per year, and the mean length of the internodes of the plants. These findings indicate that the use of regular, annual changes in the length of the internodes of mangrove seedlings can be used reliably to determine their age and to estimate their growth rate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009967401337
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  • 91
    Digitale Medien
    Digitale Medien
    Risk and evolution (1999)
    Springer
    Economic theory 13 (1999), S. 329-343 
    Details
    ISSN: 1432-0479
    Schlagwort(e): Keywords and Phrases: Risk ; Evolution ; Entrepreneur. ; JEL Classification Numbers: C72 ; D81.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Summary. I examine a Knightian (1921) model of risk using a general equilibrium model of investment and trade. A population of agents with various preference types can choose between a safe production technology and a risky production technology. In addition, the distribution of types of agents changes through a standard evolutionary dynamic. For a given population distribution, the equilibrium is in general inefficient, however, by allowing the population distribution to change in response to market generated rewards, the population will converge to one where the equilibrium is efficient and where the population as a whole behaves as if all agents were risk neutral.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001990050257
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  • 92
    Digitale Medien
    Digitale Medien
    Of mites and zen: expression studies in a chelicerate arthropod confirm zen is a divergent Hox gene (1998)
    Springer
    Development genes and evolution 208 (1998), S. 591-594 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words Arthropod ; Hox ; Evolution ; Development ; Chelicerate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We have cloned, from an oribatid mite, a gene homologous to the zerknült (zen) genes of insects and the Hox 3 genes of vertebrates. Hox genes specify cell fates in specific regions of the body in all metazoans studied and are expressed in antero-posteriorly restricted regions of the embryo. This is true of the vertebrate Hox 3 but not of the zen genes, the insect homologs, and it has been proposed that the zen genes have lost their Hox-like function in the ancestor of the insects. We studied expression of a mite Hox 3/zen homolog and found that it is expressed in a discrete antero-posterior region of the body with an anterior boundary coinciding with that of the chelicerate homolog of the Drosophila Hox gene, proboscipedia, and propose that its loss of Hox function in insects is due to functional redundancy due to this overlap with another Hox gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050219
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  • 93
    Digitale Medien
    Digitale Medien
    The PBC domain contains a MEINOX domain: Coevolution of Hox and TALE homeobox genes? (1998)
    Springer
    Development genes and evolution 208 (1998), S. 113-116 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words TALE homeobox gene ; MEINOX domain ; Hox cluster ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A recent survey of TALE superclass homeobox genes revealed a new domain upstream of the homeodomain that is conserved between the plant KNOX genes and the animal MEIS genes. At the same time, another paper identified the Drosophila gene homothorax (hth) as a homologue of the vertebrate MEIS genes, which prompted a reexamination of the sequences of the MEIS, KNOX (collectively named MEINOX) and PBC domains. Similarity of the complete MEINOX domain was found within the PBC domain. This suggests that the PBC class genes were also derived from the ancient MEINOX genes. Recently, it has been shown that the MEIS genes can interact with the Abd-B genes, whilst previous results have shown that the PBC genes interact with anterior Hox genes. This leads to the hypothesis that the duplication of an ancestral MEINOX gene into the PBC and MEIS genes happened at a point in time when the first two Hox cluster genes, an anterior one and a posterior one, emerged, and that subsequently these gene classes coevolved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050161
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  • 94
    Digitale Medien
    Digitale Medien
    Evolution of groundwater chemical composition under human activity in an oilfield (1999)
    Springer
    Environmental geology 38 (1999), S. 34-46 
    Details
    ISSN: 1432-0495
    Schlagwort(e): Key words Alkaline/acid/neutral water ; Acid rain ; Geochemical modeling ; Brine ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  Analysis and hydrogeochemical modeling of hydrocarbonate groundwater, including its buffering geochemical properties, have demonstrated that this water has undergone a geochemical transformation almost throughout the whole of one industrial region. It is known that hydrocarbonate groundwater possesses a high protective natural geochemical potential, supporting neutralization of acid atmospheric precipitation. Natural hydrocarbonate water undergoes three stages of anthropogenic transformation caused by acid atmospheric precipitation over more than 50 years. The first stage is transformation of neutral hydrocarbonate water into alkaline water, accompanied by calcite precipitation and sodium carbonate dissolution from the unsaturated zone. The second stage is transformation of alkaline water into neutral hydrocarbonate water; the hydrocarbonate content, being less than the lower limit for background concentrations, showed reduced water buffering properties or protective potential relative to acid precipitation. The third stage is transformation of neutral hydrocarbonate water into acidic water, with a complete loss of protective geochemical potential. This unfavorable ecological situation with natural geochemically hydrocarbonate groundwater shows that natural groundwater less protected from the impact of acid atmospheric precipitation is in a worse ecological condition, which is confirmed by observations in northern and Western Europe and other regions of the world.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002540050398
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  • 95
    Digitale Medien
    Digitale Medien
    The early stages of ommatidial development in the flour beetle Tribolium castaneum (Coleoptera; Tenebrionidae) (1996)
    Springer
    Development genes and evolution 206 (1996), S. 136-146 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words Compound eye development ; Equator ; Evolution ; Homology ; Tribolium (Insecta ; Coleoptera)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Using electron microscopy, the first stages of ommatidial development in the flour beetle Tribolium castaneum were analysed in relation to the cellular architecture of the adult compound eye and were compared to the corresponding patterning process in the fruit fly Drosophila melanogaster. The ommatidia of the slightly horse-shoe shaped beetle compound eye contain six peripheral and two central retinula cells. The rhabdomere of the posteriorly located central photoreceptor cell is restricted to the distal half of the rhabdom whilst that of the anterior one is restricted to its proximal half. The development of the compound eye takes place in an external eye imaginal disc. Most stages of ommatidial development, as known from Drosophila, i.e. arc-like cell groups, five-cell clusters, immature eight-cell clusters and symmetrical eight-cell clusters, are very precisely conserved between the two species. Two major differences exist: 1. In Tribolium, the cone cell precursor cells synchronously join to the immature eight-cell cluster. As a consequence, the symmetrical eight-cell cluster immediately transforms into a four-cone-cell cluster. 2. The maturing ommatidia do not undergo rotation in Tribolium. Overall, no morphological indiation for an equator in the adult Tribolium compound eye could be found. Considering the strong evolutionary conservation of early ommatidial development, homology of photoreceptor cells of distantly related insects is proposed to be inferred from their ontogenetic origin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050039
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  • 96
    Digitale Medien
    Digitale Medien
    Response to insulin and the expression pattern of a gene encoding an insulin receptor homologue suggest a role for an insulin-like molecule in regulating growth and patterning in Hydra (1996)
    Springer
    Development genes and evolution 206 (1996), S. 247-259 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words Hydra ; Insulin ; Development ; Receptor ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A gene encoding a receptor protein-tyrosine kinase closely related to the vertebrate insulin receptor has been identified in the Cnidarian Hydra vulgaris. The gene is expressed in both epithelial layers of the adult polyp. A particularly high level of expression is seen in the ectoderm of the proximal portions of the tentacles and in a ring of ectodermal cells at the border between the foot basal disk and body column. The expression pattern of the gene in asexual buds is dynamic; expression is high throughout the newly emerging bud but the area of high expression becomes restricted to the apex as the bud lengthens. When the bud begins hypostome and tentacle formation, a high level of expression appears at the bases of the emerging tentacles. Finally, a ring of high expression appears just above the foot of the bud, completing the pattern seen in the adult polyp. The presence of this receptor and its pattern of expression suggested that an endogenous molecule related to insulin plays a role in regulating cell division in the body column and in differentiation of the tentacle and foot cells in Hydra, with the switch between the two being determined by the level of the receptor. Treatment of Hydra polyps with mammalian insulin caused an increase in the number of ectodermal and endodermal cells undergoing DNA synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050050
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  • 97
    Digitale Medien
    Digitale Medien
    Evolution of homeobox genes: Q50 Paired-like genes founded the Paired class (1999)
    Springer
    Development genes and evolution 209 (1999), S. 186-197 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words Cnidaria ; Paired class ; Paired-like ; Homeobox gene ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The genes belonging to the Paired class exert primary developmental functions. They are characterized by six invariant amino acid residues in the homeodomain, while the residue at position 50 can be a serine, glutamine or lysine as in the Pax-type, Q50 Paired-like or the K50 Paired-like homeodomains respectively. Genes in this class emerged early in animal evolution: three distinct Pax genes and two Q50 Paired-like genes have recently been characterised from cnidarians. Phylogenetic molecular reconstructions taking into account homeodomain and paired-domain sequences provide some new perspectives on the evolution of the Paired-class genes. Analysis of 146 Paired-class homeodomains from a wide range of metazoan taxa allowed us to identify 18 families among the three sub-classes from which the aristaless family displays the least diverged position. Both Pax-type and K50 families branch within the Q50 Paired-like sequences implying that these are the most ancestral. Consequently, most Pax genes arose from a Paired-like ancestor, via fusion of a Paired-like homebox gene with a gene encoding only a paired domain; the Cnidaria appear to contain genes representing the ’before’ and ’after’ fusion events.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050243
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  • 98
    Digitale Medien
    Digitale Medien
    Conservation and divergence in the control of yolk protein genes in dipteran insects (1997)
    Springer
    Development genes and evolution 207 (1997), S. 264-281 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words yolk protein genes ; Calliphora ; Musca ; Evolution ; doublesex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We have investigated the conservation of regulatory elements for sex- and tissue-specific gene expression in three dipteran species, Drosophila melanogaster, Musca domestica and Calliphora erythrocephala, using the yolk protein (yp) genes. Yolk proteins of the fruitfly, medfly, housefly and blowfly are very well conserved both in their sequence and their expression in ovarian follicle cells and in fat bodies of adult females. Furthermore, yp regulation by both hormonal and nutritional factors shows similar features in all four species. To study conservation of yp regulation in dipteran insects, we tested 5′ flanking regions from one Musca yp gene and one Calliphora yp gene for enhancer functions in D. melanogaster. Two fragments of 823 and 1046 bp isolated from Musca and Calliphora yp genes, respectively, are able to direct correct expression of a reporter gene in the ovarian follicle cells of transformed Drosophila at specific stages during oogenesis. Surprisingly, these enhancers do not confer sex-specific reporter gene expression in the fat body, as expression was found in both sexes of the transformed flies. None-the-less by in vitro DNA/protein interaction assays, a 284-bp DNA region from the Musca yp enhancer was able to bind the Drosophila DOUBLESEX (DSX) protein, which in D.melanogaster confers sex-specific expression of yp. We speculate that the sex-determining pathway is not directly involved in yp regulation in Musca or Calliphora adult females, but depends instead on hormonal controls to achieve sex-specific expression of yp genes in the adult.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050114
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Homeobox genes in axolotl lateral line placodes and neuromasts (1997)
    Springer
    Development genes and evolution 207 (1997), S. 287-295 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words Sense organ embryology ; Ambystoma embryology ; Homeobox genes ; Vertebrate genetics ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Gene expression has been studied in considerable detail in the developing vertebrate brain, neural crest, and some placode-derived organs. As a further investigation of vertebrate head morphogenesis, expression patterns of several homeobox-containing genes were examined using whole-mount in situ hybridization in a sensory system primitive for the vertebrate subphylum: the axolotl lateral lines and the placodes from which they develop. Axolotl Msx-2 and Dlx-3 are expressed in all of the lateral line placodes. Both genes are expressed throughout development of the lateral line system and their expression continues in the fully developed neuromasts. Expression within support cells is highly polarized. In contrast to most other observations of Msx genes in vertebrate organogenesis, expression of Msx-2 in developing lateral line organs is exclusively epithelial and is not associated with epithelial-mesenchymal interactions. A Hox-complex gene, Hoxb-3, is shown to be expressed in the embryonic hindbrain and in a lateral line placode at the same rostrocaudal level, but not in other placodes nor in mature lateral line organs. A Hox gene of a separate paralog group, Hoxa-4, is expressed in a more posterior hindbrain domain in the embryo, but is not expressed in the lateral line placode at that rostrocaudal level. These data provide the first test of the hypothesis that the neurogenic placodes develop in two rostrocaudal series aligned with the rhombomeric segments and patterned by combinations of Hox genes in parallel with the central nervous system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050116
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    An amphioxus snail gene: Expression in paraxial mesoderm and neural plate suggests a conserved role in patterning the chordate embryo (1998)
    Springer
    Development genes and evolution 208 (1998), S. 569-577 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Key words Amphioxus ; Snail ; Neural crest ; Evolution ; Chordate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Homologs of the Drosophila snail gene have been characterized in several vertebrates. In addition to being expressed in mesoderm during gastrulation, vertebrate snail genes are also expressed in presumptive neural crest and/or its derivatives. Given that neural crest is unique to vertebrates and is considered to be of fundamental importance in their evolution, we have cloned and characterized the expression of a snail gene from amphioxus, a cephalochordate widely accepted as the sister group of the vertebrates. We show that, at the amino acid sequence level, the amphioxus snail gene is a clear phylogenetic outgroup to all the characterized vertebrate snail genes. During embryogenesis snail expression initially becomes restricted to the paraxial or presomitic mesoderm of amphioxus. Later, snail is expressed at high levels in the lateral neural plate, where it persists during neurulation. Our results indicate that an ancestral function of snail genes in the lineage leading to vertebrates is to define the paraxial mesoderm. Furthermore, our results indicate that a cell population homologous to the vertebrate neural crest may be present in amphioxus, thus providing an important link in the evolution of this key vertebrate tissue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004270050216
    Standort Signatur Erwartet Verfügbarkeit
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