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  • evolution  (60)
  • temperature  (50)
  • Springer  (110)
  • 2005-2009
  • 1995-1999  (110)
  • 1997  (110)
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  • 2005-2009
  • 1995-1999  (110)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effects of vegetation and weather on trap catches of Glossina fuscipes fuscipes near Lake Victoria, Kenya (1997)
    Springer
    Entomologia experimentalis et applicata 85 (1997), S. 231-236 
    Details
    ISSN: 1570-7458
    Keywords: Glossina fuscipes fuscipes ; vegetation ; biconical trap ; temperature ; light ; relative humidity ; monitor lizard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glossina fuscipes fuscipes Newstead was sampled in isolated thickets and forest patches near Lake Victoria, Kenya using unbaited biconical traps, between March 1992 and June 1993. Traps set at 1 m from the forest edge caught 3.3 times as many males and 5 times as many females as those set inside or 10 m away. The corresponding figures at 1 m from the edge of thicket were about 1.43 and 1.64 times, respectively. Hourly catches of males and females were positively correlated with temperature, light intensity and host (monitor lizard) prevalence, and negatively correlated with relative humidity. Light intensity and temperature were the most important variables affecting the catches of each sex. The results are discussed in relation to control and monitoring of G. f. fuscipes using traps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003179128955
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  • 2
    Electronic Resource
    Electronic Resource
    Choosing a place to grow. Importance of within-plant abiotic microenvironment for Yponomeuta mahalebella (1997)
    Springer
    Entomologia experimentalis et applicata 83 (1997), S. 171-180 
    Details
    ISSN: 1570-7458
    Keywords: within-plant heterogeneity ; tent caterpillars ; temperature ; circular statistics ; Lepidoptera ; Yponomeutidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The caterpillars of Yponomeuta mahalebella Latr. (Lepidoptera: Yponomeutidae) are monophagous on Prunus mahaleb (Rosaceae) leaves. Adult females deposit eggs in batches, which determines larval gregarious behaviour. Coupled with gregarious behaviour, caterpillars spin silk tents within they will feed until pupation. Distribution of tents in the field, their effect in microenvironmental larval growth conditions and the consequences for adult body mass and survival of larvae were studied. There was a significant trend for tents to be placed with a southward orientation. Within-plant tent orientation was related to the sun-shade pattern experienced, which was the main effect determining thermal differences between the inside and the outside of the tent. These differences appeared to affect larval growth and survival, with higher survival of larvae and heavier adults emerging from tents oriented to the south-east and east, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002908817924
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetometric Method of Investigating Fire Sites (1997)
    Springer
    Fire technology 33 (1997), S. 195-213 
    Details
    ISSN: 1572-8099
    Keywords: point of fire origin ; fire ; temperature ; plaster ; concrete ; thermal ; damage ; biotite ; magnetization ; susceptibility ; N-rays ; P-rays ; X-rays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract Magnetic susceptibility (MS) measurements were taken to determine fire exposure patterns on noncombustible structural members and compartment boundaries. These measurements led on-site fire investigators to the cause of combustion and the point of fire origin. Thermal damage to walls and to ceilings was estimated quantitatively by measuring MS and two-valent Fe ion concentration in building materials such as concrete and plaster. It was shown that these effects are preconditioned by thermochemical transformations in the mineral biotite, which is present as a component of common building materials. For the first time, the effect of a substantial and irreversible increase in biotite magnetization exposed to powerful flows of N- and P-rays was found. It is hoped that the presence of this “magnetic trace” of radiation in building materials will allow investigators to use the magnetometric method at nuclear power plant catastrophes such as that in Chernobyl. It was also shown that the influence of N- and P-rays on biotite's magnetic properties greatly differs from the thermal influence on biotite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015363605037
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  • 4
    Electronic Resource
    Electronic Resource
    Genetics of the ability of Phyllotreta nemorum larvae to survive in an atypical host plant, Barbarea vulgaris ssp. arcuata (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 37-44 
    Details
    ISSN: 1570-7458
    Keywords: Barbarea vulgaris ; Cruciferae ; Phyllotreta nemorum ; Chrysomelidae ; Alticinae ; flea beetle ; plant defence ; genetics ; sex-linkage ; X- and Y-chromosome ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A polymorphism in host plant exploitation has been discovered in the flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) where one resistant population is able to use Barbarea vulgaris R.Br. ssp. arcuata (Opiz.) Simkovics (Brassicaceae) as a host plant while a susceptible population is not. Crosses (F1, F2, and backcrosses) between the two flea beetle populations were made, and survival of the progeny on B. v. ssp. arcuata was measured. The ability of P. nemorum larvae to survive in this plant species depended on the presence of major, dominant genes (R-genes). The two most abundant R-genes in the resistant flea beetle population were X- and Y-linked, respectively. The use of B. v. ssp. arcuata as a natural host plant by the resistant population of P. nemorum seems to be an extension of the host plant range of the species. The role of sex-linked genes in the evolution of host range is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002938912809
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  • 5
    Electronic Resource
    Electronic Resource
    Variation in defences of the plant Barbarea vulgaris and in counteradaptations by the flea beetle Phyllotreta nemorum (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 25-35 
    Details
    ISSN: 1570-7458
    Keywords: Barbarea vulgaris ; Cruciferae ; Phyllotreta nemorum ; Chrysomelidae ; Alticinae ; flea beetle ; plant defence ; resistance ; host plant ; variation ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several sorts of variation in the interaction between the insect, Phyllotreta nemorum L. (Coleoptera:Chrysomelidae:Alticinae), and the plant, Barbarea vulgaris R.Br. (Brassicaceae), have been discovered: 1) genetic differences in the levels of defences in the plant, 2) genetic differences in the ability of insects to cope with the plant defences, 3) seasonal variation in levels of defences in the plant, and 4) differences between leaf types in levels of defences. Two plant accessions were suitable for larval development throughout the season while the remaining nine accessions were more or less unsuitable for larvae from the ‘susceptible’ T-population at least at certain times of the year. All accessions were suitable for the ‘resistant’ E-population throughout the year. There was a seasonal variation in levels of defences in some accessions which were unsuitable for the T-population during the summer period when beetles were present, but not during autumn and spring when the beetle were hibernating. Upper (younger) cauline leaves of these accessions had higher levels of defences than lower (older) cauline leaves. The resistant E-population used B. vulgaris as a natural host plant while the susceptible T-population did not. The use of B. vulgaris as a natural host plant by the E-population of P. nemorum seems to be an extension of the host plant range of the species. Variation in plant defences may have facilitated the switch in host plant use by the resistant flea beetle population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002990929647
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  • 6
    Electronic Resource
    Electronic Resource
    Reproduction of Diaeretiella rapae on Russian wheat aphid hosts at different temperatures (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 159-166 
    Details
    ISSN: 1570-7458
    Keywords: Diaeretiella rapae ; reproduction ; life-tables ; temperature ; Diuraphis noxia ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diaeretiella rapae (M'Intosh), a polyphagous and cosmopolitan parasite of aphids, was imported from China to the USA for biological control of Diuraphis noxia (Mordwilko), a pest of small grains. We studied several aspects of its biology on D. noxia hosts in the laboratory at 3 constant temperatures, 10.0, 21.1, and 26.7 °C. Females lived significantly longer than males at all 3 temperatures, and longevity was greatest at 10 °C, followed by 21.1 and 26.7 °C. Fecundity (= number of mummies) did not differ significantly among the 3 temperatures studied. The ovarian egg-load was 129.1 ± 9.3, and was significantly affected by the size of adult females. A pre-oviposition period ± 0.26 days) was detected at 10 °C, but not at the other temperatures. Pre-imaginal survivorship was similar among temperatures, while R o and T c decreased with temperature, and r m increased with temperature. The offspring sex ratio (proportion females) was lowest at 26.7 °C, and similar between 10.0 and 21.1 °C. In addition, the offspring sex ratio significantly declined with the age of the female parent. The suitability of D. rapae for colonization against D. noxia in North America is discussed in relation to its responses to temperature and the climate of its home range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002929500786
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of light availability on host plant chemistry and the consequences for behavior and growth of an insect herbivore (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 319-333 
    Details
    ISSN: 1570-7458
    Keywords: chlorogenic acid ; light availability ; Lycopersicon esculentum ; Manduca sexta ; protein ; rutin ; temperature ; tomatine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined how light availability influenced the defensive chemistry of tomato (Lycopersicon esculentum: Solanaceae). Tomato plants were grown either in full sunlight or under shade cloth rated at 73%. Leaves from plants grown in full sunlight were tougher, had higher concentrations of allelochemicals (chlorogenic acid, rutin and tomatine), and had less protein than leaves from plants grown in shade. We determined how these differences in host plant quality due to light availability affected the behavior and growth of a Solanaceae specialist, Manduca sexta. Both in the greenhouse and in the field, caterpillars on shade-grown plants grew heavier in a shorter amount of time than those on plants that had previously been grown in full sunlight. In contrast, the effects of previous light availability to plants on caterpillar behavior appeared to be minor. To further investigate how light availability to plants influenced herbivore growth, we examined the effects of leaf-powder diets made from tomato leaves of different ages (new, intermediate, or mature) grown in full sunlight or shade on caterpillar performance. Caterpillars fed diets made from plants grown in shade consumed less but grew faster than larvae fed diets made from tomato plants grown in full sunlight. Caterpillars fed diets made from new leaves grew larger in less time than caterpillars fed diets made from intermediate aged leaves. Caterpillars did not survive on the mature leaf powder diets. There were plant-light treatment by larval thermal regime interactions. For example, at 26:15 °C , plant-light treatment had no effect on stadium duration, but at 21:10 °C, stadium duration was prolonged with the full sunlight-new leaf diet compared with the shaded-new leaf diet. In a second diet experiment, we examined the interactive effects of protein and some tomato allelochemicals (rutin, chlorogenic acid and tomatine) on the performance of caterpillars. There were food quality by thermal regime interactions. For instance, at 26:15 °C , neither protein nor allelochemical concentration influenced stadium duration, whereas at 21:10 °C, stadium duration was prolonged with the low protein-high allelochemical diet, which simulated full sunlight leaves. In sum, light availability to plants affected defensive chemistry and protein concentration. The difference in food quality was great enough to influence the growth of a specialist insect herbivore, but the effects were temperature-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002916325052
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  • 8
    Electronic Resource
    Electronic Resource
    Inter- and intra-population differences in the effects of temperature on postdiapause development of Delia radicum (1997)
    Springer
    Entomologia experimentalis et applicata 84 (1997), S. 255-265 
    Details
    ISSN: 1570-7458
    Keywords: Delia radicum ; postdiapause development ; temperature ; Diptera ; Anthomyiidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Canadian populations of D. radicum differ in their response to temperature during postdiapause development. Populations that are primarily of the early-emerging type ( $$\left( { \leqslant 256DD_{04} } \right)$$ ) (St-Jean, Quebec; London, Ontario) have high values for the parameters describing this response: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuamaaBa% aaleaacaWGTbaabeaakiabg2da9aaa!38F2!$$R_m = $$ 12.7–13.3; $$T_m = $$ 28.0–31.8 °C ; Tσ = 10.3–14.2 ( $$R_m $$ , the maximum developmental rate at the temperature, $$T_m $$ [ °C ] where the developmental rate is highest, and Tσ , the parameter which gives the shape of the truncated normal curve fitted to the data), a low degree-day requirement for emergence (160–232 $$DD_{04} $$ ), and may lack a developmental delay at temperatures above ca. 21 °C . Populations of the late-emerging type (Kildare, Prince Edward Island) have low parameter values ( $$ R_m = 2.5$$ , $$T_m = 19.3$$ °C ; Tσ = 6.4), high degree-day requirements (530 $$DD_{04} $$ ), and a developmental delay at high temperatures. The parameters for the early-emergers in the population from Winnipeg, Manitoba (74% early) were intermediate ( $$R_m = 9.1$$ , $$T_m = 27.1$$ °C , Tσ = 10.7, $$ DD_{04} = 246 $$ ), but resembled the early rather than the late type. This population varied from 31 to 90% early type over a 10-year period and the rate of postdiapause development at 20 °C was directly related to the percentage early. In the year with the most rapid development (90% early), development was significantly slower than in the populations from other locations with predominantly early populations, and the year with the slowest development (31% early) showed significantly faster development than that from Kildare, Prince Edward Island (100% late). Therefore the parameters for early and late types of development will not be accurate for use in mixed populations, and the parameters in mixed populations will change among years. Populations of D. radicum in North America and Europe (67 locations by years) varied from 0–100% early. At Winnipeg, the percentage early was directly related to the annual temperature accumulation ( $$DD_{05} $$ ) during the growing season. The calculation of developmental parameters for the early-emergers of mixed populations provides a more accurate basis for estimating the times of first emergence and the first peak of emergence than parameters based on the whole population. Since postdiapause developmental rates vary both among and annually within locations, developmental models should be designed to include such variations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003048502446
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of temperature on performanceof LaNi4.76Sn0.24 metal hydride electrode’ (1997)
    Springer
    Journal of applied electrochemistry 27 (1997), S. 1328-1332 
    Details
    ISSN: 1572-8838
    Keywords: metal hydride ; capacity ; temperature ; performance ; enthalpy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of temperature on the performance of a LaNi4.76Sn0.24 metal hydride electrode was investigated in the temperature range of 0 to 50°C. The electrode showed a maximum discharge capacity at 25°C. The total resistance increases with a decrease of temperature from 50°C to 0°C. The apparent activation enthalpies at different states of charge were determined by evaluating the polarization resistance at different temperatures. It was found that the apparent activation enthalpy is an indicator of the relative reaction rate of the charge-transfer reaction and hydrogen absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018460709968
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of time-dependent speed on frictional heat generation and wear in transient axisymmetrical contact of sliding (1997)
    Springer
    Archive of applied mechanics 67 (1997), S. 331-338 
    Details
    ISSN: 1432-0681
    Keywords: Key words frictional heating ; wear ; contact pressure ; temperature ; brake system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary A transient contact problem with frictional heating and wear for two nonuniform sliding half-spaces is considered. One of the two half-spaces is assumed to be slightly curved to give a Hertzian initial pressure distribution: the other is a rigid nonconductor. Under the assumption that the contact pressure distribution could be described by Hertz formulas during all the process of interaction, the problem is formulated in terms of one integral equation of Volterra type with unknown radius of contact area. A numerical solution of this equation is obtained using a piecewise-constant presentation of an unknown function. The influence of operating parameters on the contact temperature and the radius of the contact area is studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050121
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  • 11
    Electronic Resource
    Electronic Resource
    Colonization and evolution of lakes on the central Norwegian coast following deglaciation and land uplift 9500 to 7800 years B.P. (1997)
    Springer
    Journal of paleolimnology 18 (1997), S. 269-281 
    Details
    ISSN: 1573-0417
    Keywords: colonization ; evolution ; lakes ; Norway ; deglaciation ; land uplift ; invertebrates ; Chironomidae ; Porifera ; Bryozoa ; diatoms ; Charophyta ; tsunami
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Invertebrate colonization of lakes following the uplift of land from the sea was studied in four lakes, currently situated between 39 and 24 m a.s.l., on the central Norwegian coast. The lakes were isolated from the sea between 9500 and 7700 years B.P. Animal and algal remains picked from core samples showed that the first colonizers preserved as fossils were usually members of the Chironomidae, Daphnidae/Chydoridae, Acarina, Porifera (Ephydatia mülleri and Spongilla lacustris), Bryozoa (Cristatella mucedo and Plumatella spp.) and Charophyta (Chara sp.). Of the chironomids, the genus Chironomus was present in the oldest lacustrine layers of all four lakes, but other genera recorded at the marine/lacustrine boundary were Dicrotendipes, Procladius (?), Einfeldia, Microtendipes, and Glyptotendipes. Remains of the caddis fly family Limnephilidae were also present in the earliest lacustrine sediments in Kvennavatnet and Kvernavatnet. The oldest invertebrate fauna is typical for mesotrophic lakes. However, chironomids and mites have been present in this area from at least about 10 500 years B.P. A diverse chironomid community was established between 300 and 800 years after isolation from the sea at Kvernavatnet on the island of Hitra, while only between 80 and 120 years passed before a comparably diverse community developed at Kvennavatnet on the mainland coast. A similar development of the invertebrate fauna occurred in Kvennavatnet, Kvernavatnet and Storkuvatnet. However, Litjvatnet deviates greatly from the ‘normal’ pattern because a tsunami disturbed the bottom sediments and fauna. The tsunami, a gigantic sea wave, was caused by a submarine slide from the Norwegian continental slope. It reached Litjvatnet, today located 24 m a.s.l., but was not traced in Storkuvatnet at 30 m a.s.l. This event happened about 7200 years B.P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007934825272
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  • 12
    Electronic Resource
    Electronic Resource
    Effect of environmental conditions and inoculum density on infection of guava fruits by Colletotrichum glososporioides (1997)
    Springer
    Mycopathologia 137 (1997), S. 165-172 
    Details
    ISSN: 1573-0832
    Keywords: Anthracnose ; guava ; Colletotrichum glososporioides ; temperature ; free moisture ; inoculum density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The influence of environmental factors (temperature and humidity), inoculum density on infection by Colletotrichum glososporioides and development of anthracnose lesions were determined on uninjured, sand-injured and punctured fruits. The optical temperature for severe infection was 30 °C, whereas the disease incidence was less at 20 and 35 °C. Inoculated guavas that received 1–60 h of continuous free moisture developed lesions, but the disease was minimal (0–7%) after 1–6 h free moisture. Infection rates of uninjured, sand-injured and punctured fruits receiving 60 h of free moisture were 34, 70 and 100%, respectively. Disease incidence increased as inoculum density increased from 101 to 106 conidia/ml. In field conditions, the development of anthracnose lesions was greater on punctured guavas than on uninjured or sand-injured ones, in both rainy and winter seasons. In general, the number of lesions was highest in sand-injured fruits, followed by punctured and uninjured fruits. In rainy season the number of lesions on injured and uninjured fruits was greater than similarly treated guavas in winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006842801828
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  • 13
    Electronic Resource
    Electronic Resource
    Effect of temperature on antagonistic and biocontrol potential of shape Trichoderma sp. on Sclerotium rolfsii (1997)
    Springer
    Mycopathologia 139 (1997), S. 151-155 
    Details
    ISSN: 1573-0832
    Keywords: Antagonism ; biocontrol ; ginger ; postharvest rot ; Sclerotium rolfsii ; Trichoderma ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sclerotium rolfsii is a destructive soil-borne and postharvest plant pathogen. Use of the antagonistic fungus Trichoderma sp. has been earlier reported by us to successfully control this pathogen under postharvest conditions. In the present paper we report on the effects of temperature on the growth and biocontrol potential of Trichoderma sp. on S. rolfsii. Experimental results indicated that S. rolfsii and Trichoderma sp. have different temperature optima for growth: 30–35 °C for the pathogen and 25–30 °C for the antagonist. In dual culture, Trichoderma overgrew S. rolfsii at 25 °C and 30 °C, but at 35 °C and 37 °C, S. rolfsii overgrew the colony of Trichoderma. Trichoderma produced higher concentration of fungitoxic metabolites in broth culture at higher temperatures. In bioassays using ginger slices and whole rhizomes, it has been demonstrated that Trichoderma is not very effective in suppressing S. rolfsii at temperatures above 30 °C. In light of these results, possible mechanisms of biocontrol of S. rolfsii as a postharvest pathogen has been discussed. Storage temperature has been suggested as a critical factor in biocontrol of S. rolfsii.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006868009184
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  • 14
    Electronic Resource
    Electronic Resource
    Evolution of novel metabolic pathways for the degradation of chloroaromatic compounds (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 159-178 
    Details
    ISSN: 1572-9699
    Keywords: aromatic pathways ; chlorobenzenes ; evolution ; genes ; plasmids ; pseudomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorobenzenes are substrates not easily metabolized by existing bacteria in the environment. Specific strains, however, have been isolated from polluted environments or in laboratory selection procedures that use chlorobenzenes as their sole carbon and energy source. Genetic analysis indicated that these bacteria have acquired a novel combination of previously existing genes. One of these gene clusters contains the genes for an aromatic ring dioxy-genase and a dihydrodiol dehydrogenase. The other contains the genes for a chlorocatechol oxidative pathway. Comparison of such gene clusters with those from other aromatics degrading bacteria reveals that this process of recombining or assembly of existing genetic material must have occurred in many of them. Similarities of gene functions between pathways suggest that incorporation of existing genetic material has been the most important mechanism of expanding a metabolic pathway. Only in a few cases a horizontal expansion, that is acqui sition of gene functions to accomodate a wider range of substrates which are then all transformed in one central pathway, is observed on the genetic level. Evidence is presented indicating that the assembly process may trigger a faster divergence of nearby gene sequences. Further ‘fine-tuning’, for example by developing a proper regulation, is then the next step in the adaptation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000166400935
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  • 15
    Electronic Resource
    Electronic Resource
    Evolution of bacterial genomes (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 265-270 
    Details
    ISSN: 1572-9699
    Keywords: bacteria ; DNA ; evolution ; genome ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review examines evolution of bacterial genomes with an emphasis on RNA based life, the transition to functional DNA and small evolving genomes (possibly plasmids) that led to larger, functional bacterial genomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000123216769
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  • 16
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    Bacterial evolution and metabolism (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 257-263 
    Details
    ISSN: 1572-9699
    Keywords: bacteria ; energy ; evolution ; genome ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This article examines the relationship between (or dependence of) bacterial evolution in prokaryotes and metabolism, and the changing physical-chemical conditions present during early evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000175217677
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  • 17
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    Molecular evolution in bacteria: Surfaces, cathodes and anodes (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 363-368 
    Details
    ISSN: 1572-9699
    Keywords: assembly ; anode ; bacteria ; cathode ; DNA ; evolution ; genetics ; molecular ; surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular evolution is examined in bacteria with an emphasis on mineral surfaces, membranes, cathodes and anodes. In early molecular evolution, cathode-anode system may have been naturally occurring on a nm to µm scale. Secondly, the cathode-anode system could have been separated by a primitive, permeable lipid or microsphere on a mineral surface, that was a precursor of a more advanced membrane with a charge differential on either side of the membrane. These aspects will be considered from a theoretical evolutionary perspective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000271219036
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  • 18
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    Molecular evolution and optimization (1997)
    Springer
    Antonie van Leeuwenhoek 72 (1997), S. 251-259 
    Details
    ISSN: 1572-9699
    Keywords: bacteria ; catalysis ; DNA ; enzyme ; evolution ; microorganisms ; optimization ; RNA ; time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microbial populations (and life) not only evolve, they optimize. The transition from a random, unorganized, lifeless Earth to the present situation, where the Earth is virtually covered with nucleic acids and diverse and complex species, required numerous molecular changes and the integration of metabolic pathways over billions of years. Primitive prokaryotic life was dependent on and constrained by the physical-chemical conditions on the Earth, while slowly reshaping conditions present. In this review, molecular evolution and molecular optimization are examined with an emphasis on the order in which evolutionary events occurred.
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    URL: http://dx.doi.org/10.1023/A:1000456825081
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    Comparative studies on some analytical methods (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 857-862 
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    ISSN: 1572-8943
    Keywords: analytical methods ; kinetics ; powder milk ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This work present comparative results on powder milk storage quality, obtained from analytical methods. Protein content was determined conventional (Kjeldahl) and colorimetric with biuret reagent at 540 nm and integral quality by thermogravimetric and biological methods. A method was developed for the protein separation of powder milk. Powder milk was submitted to degradation processes at 45, 60 and 80°C for 20 days. The results indicated that protein content values were inconsistent if determinations by Kjeldahl and colorimetric methods and biological tests were compared. There is evidence of thermal decomposition of powder milk as detected by biological and thermogravimetric methods.
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    URL: http://dx.doi.org/10.1007/BF01996770
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    Measurement by LASER-Generated Ultrasound of Four Stiffness Coefficients of an Anisotropic Material at Elevated Temperatures (1997)
    Springer
    Journal of nondestructive evaluation 16 (1997), S. 91-100 
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    ISSN: 1573-4862
    Keywords: LASER ultrasound ; anisotropic material ; group velocity ; stiffness coefficients ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Ultrasonic waves are generated through a composite material by means of a noncontact technique. It uses a Nd:Yag LASER for the generation and an interferometric probe for the detection of acoustic waveforms. From a suitable set of experimental data, an inversion scheme is used for the recovering of four stiffness coefficients. They characterize the elasticity in a principal plane of symmetry of the material which exhibits an orthorhombic symmetry. The measurements are performed at various temperatures, elevated by steps up to 300°C for two specimen. The sensitivity of the method appears convenient to measure the temperature induced stiffness changes. The anisotropic degradation of the material properties are then pointed out.
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    URL: http://dx.doi.org/10.1023/A:1022620501899
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    The Glycophorin A Gene Family in Gorillas: Structure, Expression, and Comparison with the Human and Chimpanzee Homologues (1997)
    Springer
    Biochemical genetics 35 (1997), S. 59-76 
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    ISSN: 1573-4927
    Keywords: glycophorins ; gorilla ; evolution ; gene family ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Homologues of MN blood group antigens, encoded by members of the glycophorin A (GPA) gene family, are expressed in man, anthropoid apes, and some species of Old World monkeys. Previous studies had shown that a three-gene framework, most closely related to that in man, is present in the chimpanzee. Here we report the genomic structure, transcript map, and protein expression of the GYPA locus in gorillas. Compared to the corresponding human and chimpanzee homologues, gorilla GPA, GPB, and GPB/E genes each showed a high degree of sequence identity, with the same exon-intron organization. However, the expression of exons III, IV, or V encoding the extracellular or membrane domains of homologous glycophorins varied among the three species. Gorilla GPA and GPB/E genes were unique in that the former occurred in two allelic forms with or without the expression of exon III, whereas the latter contained one (ψ exon III) instead of two silenced exons (ψ exons III and IV). Differences from human but not chimpanzee GPA also included the presence of a hybrid M/N epitope and the absence of the sequon for N-glycosylation. Owing to the retention of a functional exon III, gorilla GPB was more similar to chimpanzee GPB than human GPB. A transspecies allele was identified in the gorilla that gave rise to the Henshaw (He)-like antigen similar to that found in man. These results provide further insight into the model for evolution of the GPA gene family, indicating that the mechanisms underlying inter- and intraspecific polymorphism of glycophorins could predate the divergence of gorillas as the consequence of gene duplication and diversification.
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    URL: http://dx.doi.org/10.1023/A:1022212630370
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    Multiple Functions for Secondary Metabolites in Encrusting Marine Invertebrates (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 1527-1547 
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    ISSN: 1573-1561
    Keywords: Secondary metabolites ; chemical defense ; evolution ; ascidians ; sponges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We used three chemical fractions (spanning a wide range of polarities) from the extracts of four marine invertebrates, the spongesCrambe crambe andHemimycale columella and the ascidiansCystodytes dellechiajei andPolysyncraton lacazei, to test inhibition of cell division, photosynthesis, and settlement. We used assay organisms from the same habitat, seeking to determine whether a species may display diverse, ecologically relevant bioac-tivities and, if so, whether the same types of compound may be responsible for such activities. Cell division was strongly inhibited by the spongeC. crambe. A dichloromethane fraction fromC. crambe prevented development of sea urchinParacentrotus lividus eggs at a concentration of 10 μg/ml, as did the butanolic fraction, but at higher concentrations (50 and 100 μg/ml). At 50 μg/ml, the aqueous fraction ofC. crambe allowed cell division but prevented eggs from developing beyond the gastrula stage. Similar results were recorded with the dichloromethane fraction ofP. lacazei and from the aqueous fraction ofH. columella. Photosynthesis was unaffected by any of the species at 50 μg/ml. Larval settlement was inhibited by one or another fraction from the four species surveyed at a concentration of 50 μg/ml, althoughC. crambe exhibited the greatest amount of activity. We therefore found that various fractions displayed the same type of bioactivity, while compounds from the same fraction were responsible for multiple activities, suggesting that secondary metabolites are multiple-purpose tools in nature, which is relevant to our understanding of species ecology and evolution. Moreover, results showed that the assessment of the role of chemical compounds is significantly influenced by the assay organism, fractionation procedure, concentration, and duration of experiments. All these factors should be carefully considered when testing ecological hypotheses of the roles of chemically-mediated bioactivities.
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    The effect of condensation on sporulation ofHelminthosporium solani on potato tubers infected with silver scurf and held in simulated store conditions (1997)
    Springer
    Potato research 40 (1997), S. 169-180 
    Details
    ISSN: 1871-4528
    Keywords: skin resistance ; temperature ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Chambers were designed to simulate environmental conditions present in commercial potato stores and were used to introduce condensation to tubers infected with silver scurf (Helminthosporium solani). The electrical resistance measured across the skin of tubers from the top of the chambers was consistently lower than that from the bottom of the chamber, and this was reflected in an increased number ofH. solani spores produced by the top tubers. An increase in the length of the condensation period resulted in the skin resistance remaining lower for a longer period and also resulted in higher number of spores. Tubers held at relatively high ambient temperatures (15 °C) required a shorter period of condensation to cause an increase in spore count. This investigation highlighted the need for close monitoring of store environments so that condensation events can be quickly identified and the tubers dried.
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    The effect of some environmental factors on potato tuber numbers (1997)
    Springer
    Potato research 40 (1997), S. 297-306 
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    ISSN: 1871-4528
    Keywords: light ; temperature ; stolon growth medium ; below ground nodes ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Five experiments studied the effects of shading, temperature and stolon growth medium on stolon and tuber formation. The lowest numbers of stolons and tubers were produced at the higher and lower nodes. Numbers of primary stolons and tubers were relatively stable across nodes and treatments and variation in total numbers was largely due to changes in numbers of lateral and branch stolons. In the field, 70% shading reduced numbers of stolons and tubers by reducing lateral and branch stolons, while in hydroponics, 45% shading and temperatures at initiation had no effect on tuber numbers. In both environments later planting tended to reduce numbers of stolons and tubers. There were large effects of the physical environment, with compost producing three times as many tubers as dry vermiculite. The potential number of tubers may be determined by the number of stolons and the environmental conditions affecting stolon formation and development.
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    Revision ofDoniophyton (Compositae, Barnadesioideae) (1997)
    Springer
    Plant systematics and evolution 206 (1997), S. 33-45 
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    ISSN: 1615-6110
    Keywords: Compositae ; Barnadesioideae ; Doniophyton ; Chuquiraga ; Argentina ; Chile ; evolution ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This revision describes, illustrates and documents morphological variation inDoniophyton (Compositae, Barnadesioideae), restricted to Argentina and Chile. Two species are recognized,D. anomalum andD. weddellii (sp. nova), possessing distinct morphological and chromosomal features, elevational tolerances, and nearly allopatric distributions.Doniophyton weddellii occurs primarily in central to northern Andean Chile and Argentina from 1900–4000 m a. s. l.;D. anomalum is found principally in centralwestern Argentina and south into Patagonia at 0–1800 m a. s. l. Close relationship exists withChuquiraga of subfam.Barnadesioideae. It is hypothesized thatDoniophyton evolved out ofChuquiraga in the high central Andes between Chile and Argentina. It is suggested thatD. weddellii differentiated first, correlating with an aneuploid chromosomal decrease from n = 27 (inChuquiraga) to n = 25. Further evolution and chromosomal decrease to n = 24 resulted inD. anomalum, with accompanying migration into southern Andes and Patagonia. Nomenclatural changes result from examination of protologues and type specimens:Doniophyton anomalum replaces the commonly used nameD. patagonicum, and a new species,D. weddellii, is described for the taxon masquerading under the routinely used superfluous nameD. andicola.
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    Aphanomyces frigidophilus sp. nov. from eggs of Japanese char,Salvelinus leucomaenis (1997)
    Springer
    Mycoscience 38 (1997), S. 135-140 
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    ISSN: 1618-2545
    Keywords: Aphanomyces frigidophilus ; morphology ; pH ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aphanomyces frigidophilus sp. nov. was obtained from eggs of Japanese char,Salvelinus leucomaenis, from Tochigi Prefectural Fisheries Experimental Station, Utsunomiya, Japan. Vegetative hyphae were delicate, slightly wavy, moderately branched. Zoosporangia were isodiametric with the vegetative hyphae. Oogonia were abundant, originating on short stalks from lateral sides of hyphae. Oogonia were spherical, subspherical or pyriform, with a single subcentric oospore inside. Outer surfaces of oogonia were roughened with short papillate, crenulate or irregular ornaments. Antheridia and oospore germination were not observed. Zoospore germination and vegetative growth were found from pH 5.0 to 11.0. Zoospore production was highest at 10°C, whereas rapid growth occurred at 20–25°C. Vegetative growth of the fungus declined from the maximal level at 25°C to less than half maximal at 30°C and completely disappeared at 35°C.
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    “Just-so” stories about “inner cognitive Africa”: some doubts about Sorensen's evolutionary epistemology of thought experiments (1997)
    Springer
    Biology and philosophy 12 (1997), S. 207-224 
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    ISSN: 1572-8404
    Keywords: evolution ; epistemology ; evolutionary epistemology ; naturalized epistemology ; thought experiments ; modality ; utility ; fitness ; adaptation ; reliability ; possible worlds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Roy Sorensen advances an evolutionary explanation of our capacity for thought experiments which doubles as a naturalized epistemological justification. I argue Sorensen”s explanation fails to satisfy key elements of environmental-selectionist explanations and so fails to carry epistemic force. I then argue that even if Sorensen succeeds in showing the adaptive utility of our capacity, he still fails to establish its reliability and hence epistemic utility. I conclude Sorensen”s account comes to little more than a “just-so story”.
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    Taking the ‘Error’ Out of Ruse‘s Error Theory (1997)
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    Biology and philosophy 12 (1997), S. 385-397 
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    ISSN: 1572-8404
    Keywords: morality ; evolution ; error theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Michael Ruse‘s Darwinian metaethics has come under just criticism from Peter Woolcock (1993). But with modification it remains defensible. Ruse (1986) holds that people ordinarily have a false belief that there are objective moral obligations. He argues that the evolutionary story should be taken as an error theory, i.e., as a theory which explains the belief that there are obligations as arising from non-rational causes, rather than from inference or evidential reasons. Woolcock quite rightly objects that this position entails moral nihilism. However, I argue here that people generally have justified true beliefs about which acts promote their most coherent set of moral values, and hence, by definition, about which acts are right. What the evolutionary story explains is the existence of these values, but it is not an error theory for moral beliefs. Ordinary beliefs correspond to real moral properties, though these are not objective or absolute properties independent of anyone‘s subjective states. On its best footing, therefore, a Darwinian metaethics of the type Ruse offers is not an error theory and does not entail moral nihilism.
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    Periodic changes in metal content in Fucus distichus thalli under polar day conditions (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 269-276 
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    ISSN: 1573-5176
    Keywords: Fucus distichus ; polar day ; trace metals ; light ; temperature ; tide ; rhythms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variation of Mn, Fe, Ni, Cu and Zn contents in thalli of Fucus distichus was determined under conditions of polar days. The use of spectrum analysis allowed estimates comparisons of the interrelation of periodic changes in irradiance, temperature and tidal fluctuations and quasiperiodic changes in metal contents. The effect of the diel rhythm of irradiance correlated with the accumulation of all metals except for Zn. At the same time, the changes in Mn, Fe and Cu content were delayed in respect to changes in irradiance level. The phase shift for Fe was 1 h 56 min, for Cu – 3 h 41 min and for Mn – 5 h5 min. The change in Ni content, in contrast, was 11min ahead of the change in irradiance. During the experiment an increase in water temperature up to10 °C resulted in increases in the average Mn, Ni and Cu contents in the thalli and decreases in Fe and Zn concents. The periodicity of metal thallus content did not always correspond to a diurnal rhythm, and couldbe longer (Mn, Ni: 32 h; Fe: 36 h) or shorter (Mn, Ni, Zn: 16 h; Cu: 12 h; Zn: 20, 10 h). The ANOVA of these rhythms allows an estimate of the contribution of rising and falling tidal fluctuations to the changes in Cu, Mn and Ni contents. There was a higher metal content during a falling than a rising tide. Abbreviations SDLT – semidiurnal lunartide, CDLT – closed diurnal lunar tide.
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    Polar cyanobacteria versus green algae for tertiary waste-water treatment in cool climates (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 371-381 
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    ISSN: 1573-5176
    Keywords: Antarctic ; Arctic ; cyanobacteria ; green algae ; mass algal culture ; Phormidium ; temperature ; waste-water treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-nine strains of filamentous, mat-forming cyanobacteria isolated from the Arctic, subarctic and Antarctic environments were screened for their potential use in outdoor waste-water treatment systems designed for cold north-temperate climates. The most promising isolate (strain E18, Phormidium sp. from a high Arctic lake) grew well at low temperatures and formed aggregates (flocs) that could be readily harvested by sedimentation. We evaluated the growth and nutrient uptake abilities of E18 relative to a community of green algae (a Chlorococcalean assemblage, denoted Vc) sampled from a tertiary treatment system in Valcartier, Canada. E18 had superior growth rates below 15°C Canada. (µ = 0.20 d-1 at 10°C under continuous irradiance of 225 µmol photon m-2 s-1) and higher phosphate uptake rates below 10°C (k = 0.050 d-1 at 5°C) relative to Vc (µ=0.087 d-1 at 10°C and k = 0.020 d-1 at 5°C, respectively). The green algal assemblage generally performed better than E18 at high temperatures (at 25°C, µ = 0.39 d-1 and k = 0.34 d-1 for Vc; µ = 0.28 d-1 and k = 0.33 d-1 for E18). However, E18 removed nitrate more efficiently than Vc at most temperatures including 25°C. Polar cyanobacteria such as strain E18 are appropriate species for waste-water treatment in cold climates during spring and autumn. Under warmer summer conditions, fast-growing green algae such as the Vc assemblage are likely to colonize and dominate, but warm-water Phormidium isolates could be used at that time.
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    As integrated culture system for outdoor production of microalgae and cyanobacteria (1997)
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    Journal of applied phycology 9 (1997), S. 113-119 
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    ISSN: 1573-5176
    Keywords: Arthrospira (Spirulina) platensis ; integrated culture system ; raceway pond ; photobioreactor ; alveolar panel ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultivation of microalgae in closed photobioreactors suffers from high temperatures, whereas in open raceway ponds the optimal temperature is seldom reached. With an integrated device coupling a raceway pond with a suitably sized and positioned closed system (alveolar panel), the heat accumulated in the panel was efficiently transferred to the pond and a near-optimum temperature regimen for Arthrospira platensis was maintained, with no need for any additional cooling device. The productivity obtained in the integrated system was higher than the sum of the productivities (g reactor−1 day−1) of the pond and panel systems operating separately.
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    Factors controlling the growth of field populations of Hydrodictyon reticulatum in New Zealand (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 229-236 
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    ISSN: 1573-5176
    Keywords: nutrients ; growth rate ; Hydrodictyon reticulatum ; seasonal changes ; temperature ; growth prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Since Hydrodictyon reticulatum was introduced to New Zealand it has spread rapidly and produced persistent annual nuisance growths in areas where nuisance algal had not occurred previously. Field bioassays were conducted at 10 sites between August 1993 and February 1995 to evaluate the seasonal growth patterns and the factors controlling growth under natural conditions. H. reticulatum exhibited a strong seasonal growth pattern with growth rates up to 0.33 doublings d-1 from August to March, are duction in growth rate in April and little or no growth from May to July. The H. reticulatum present in New Zealand has are latively low requirement for dissolved inorganic nitrogen (DIN) in comparison with other nuisance species, with its growth rate being saturated at 200 mg m-3. This and the high affinity for DIN as shown by a Ks of 29 mg m-3 have been key factors in the establishment of nuisance growths of H. reticulatum in New Zealand.
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    Effects of temperature and growth phase on lipid and biochemical composition of Isochrysis galbana TK1 (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 451-457 
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    ISSN: 1573-5176
    Keywords: Isochrysis galbana ; lipid ; biochemical composition ; fatty acid ; temperature ; growthphase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lipid and biochemical composition of the haptophyte Isochrysis galbana TK1 was examined. Cultures were grown at 15 °C and 30 °C, and harvested in the exponential and early stationary growth phases. Carbohydrate and protein content varied at the two culture temperatures and growth phases. The highest protein content was found at the exponential growth phase at 15 °C, and the highest carbohydrate content was found at the stationary phase at the same culture temperature. Lipid accumulated in the stationary growth phase and its content was higher at 30 °C than at 15 °C regardless of the growth phase. The neutral lipids were the major class of lipid found in all the cultures. The stationary phase culture had a higher proportion of neutral lipids than the exponential phase culture and the proportion decreased slightly when culture temperature was increased from 15 °C to 30 °C. Phospholipid levels remained constant at the two temperatures, but slightly decreased in the stationary phase. Glycolipids in the exponentially growing cells were higher than those from stationary growth phase and increased with temperature. Polyunsaturated fatty acids (PUFAs) predominated in glycolipids and phospholipids. Cells grown at 15 °C contained higher proportion of 18:3 (n–3) and 22:6 (n–3) with a corresponding decrease in 18:2 (n–6), monounsaturated and saturated fatty acids.
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    Somatic and population growth in selected cladoceran and rotifer species offered the cyanobacterium it Microcystis aeruginosa as food (1997)
    Springer
    Aquatic ecology 31 (1997), S. 283-298 
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    ISSN: 1573-5125
    Keywords: toxicity ; cyanobacteria ; zooplankton ; population growth ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ability of cladocerans and rotifers to utilise the cyanobacterium Microcystis aeruginosa was tested by comparing the somatic and population growth in cultures using Chlorella and Microcystis as food types. Five species of cladocerans (Ceriodaphnia cornuta, Scapholeberis kingi, Moina macrocopa, Daphnia carinata, Simocephalus vetulus) and two species of rotifers (Brachionus calyciflorus, Hexarthra mira) were used in this study. In order to exclude the possibility of poor utilisation of Microcystis due to mechanical interference, single cells of Microcystis, (obtained by sonicating large colonies) were also offered. Experiments were done at 20 °Cs and 30 °C . In all the treatments tested, the population growth rate per day of the cladocerans ranged from -0.715 to 0.612 and that of the rotifers from -1.15 to 0.781. While C. cornuta, S. kingi and S. vetulus could utilise Microcystis, M. macrocopa and D. carinata were extremely susceptible to its toxins. The ability of the cladoceran populations to grow on Microcystis single cells was not related to the body length or gut length alone but to their ratio. The toxic effects of Microcystis were mitigated at the higher temperature. A strain of C. cornuta, collected from a Microcystis-dominated lake, had a higher growth rate on the toxic cyanobacteria suggesting that the tolerance to Microcystis could be a heritable trait. Of the two rotifer species, only H. mira survived and reproduced in some treatments of Microcystis.
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    Chloroplast changes and differentiation of callus cells in Eckloniopsis radicosa (Kjellman) Okamura (Phaeophyta, Laminariales) (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 175-178 
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    ISSN: 1573-5176
    Keywords: callus cells ; chloroplast ; differentiation ; Eckloniopsis radicosa ; Laminariales ; light intensity ; Phaeophyta ; temperature ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Excised rectangular blade pieces of young sporophytes of Eckloniopsis radicosa (Kjellman) Okamura were cultured at four different temperatures (10, 15, 20, 25 °C) and light intensities (10, 20, 40, 80 µmol photon m−2 s−1) to observe callus cell propagation and differentiation. Although rapidly propagating callus cells were observed at a low temperature (15 °C) and low light intensities of (10–20 µmol photon m−2 s−1), differentiation to bladelets was only observed at higher temperatures and light intensities. In rapidly propagating callus cells, the chloroplasts decreased in both size and number. When callus cells with few chloroplasts were exposed to high temperature and light intensity, the chloroplasts gradually increased in number and size until they were the same size as found in cells from young blades. Finally, these cells differentiated and produced bladelets. This is the first report describing a relationship between differentiation and chloroplast size and number in the callus cells on E. radicosa.
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    Evolution of the Sacoglossa (Mollusca, Opisthobranchia) and the ecological associations with their food plants (1997)
    Springer
    Evolutionary ecology 11 (1997), S. 301-335 
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    ISSN: 1573-8477
    Keywords: ecological associations ; evolution ; integrative biology ; Opisthobranchia ; resource tracking ; Sacoglossa ; Ulvophyceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolution in the opisthobranch order Sacoglossa has been closely linked to their specialized suctorial herbivorous habits. All shelled Sacoglossa (about 20% of the species) feed on one algal genus, Caulerpa. The non-shelled Sacoglossa have 'radiated' to other diets, mainly siphonalean or septate green algae (Class Ulvophyceae). Comparing the phylogeny of sacoglossan genera with the phylogeny of the Ulvophyceae indicates that co-speciation may have taken place at the basal node of the Sacoglossa, and that host switching has taken place several times in the two non-shelled clades. It is suggested that the most important evolutionary process has been speciation by 'resource-tracking'; the resource tracked is most probably cell wall composition of the algal prey. The fossil record of extant sacoglossan genera dates back to the Eocene and, based on the fossil record of siphonalean green algae, the Sacoglossa most likely appeared in the Cretaceous. It is hypothesized that the ancestral sacoglossan was epifaunal, suctorial and herbivorous, and the 'ancestral' food plant was not Caulerpa, but filamentous, calcified, now extinct, Udoteaceae.
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    URL: http://dx.doi.org/10.1023/A:1018468420368
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    The evolution of dispersal in a two-patch system:Some consequences of differences between migrants and residents (1997)
    Springer
    Evolutionary ecology 11 (1997), S. 613-629 
    Details
    ISSN: 1573-8477
    Keywords: dispersal ; evolution ; evolutionarily stable strategy ; migrant ; resident ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigate how age-structure and differences in certain demographic traits between residents and immigrants of a single species act to determine the evolutionarily stable dispersal strategy in a two-patch environment that is heterogeneous in space but constant in time. These two factors have been neglected in previous models of the evolution of dispersal, which generally consider organisms with very simple life-cycles and assume that, whatever their origin, individuals in a given habitat have the same bio-demographic characteristics. However, there is increasing empirical evidence that dispersing individuals have different demographic properties from phylopatric ones. We develop a matrix model in which recruitment depends on local population densities. We assume that dispersal entails a proportional cost to immigrant fecundity, which can be compensated by differences in survival rates between immigrants and residents. The evolutionarily stable strategies (ESS) for dispersal are identified using a combination of analytical expressions and numerical simulations. Our results show that philopatry is selected (1) when dispersal rates do not vary in space, (2) when the metapopulation is a source-sink system and (3) when dispersal rates vary in space (asymmetric dispersal) and immigrants do not compensate for their reduced fecundity. We observe that non-zero asymmetric dispersal rates may be evolutionarily stable when (1) immigrants and residents are demographically alike and (2) immigrants compensate totally for their reduced fecundity through an increase in adult survival. Under these conditions, we find that the ESS occurs when the fitnesses at equilibrium in the two habitats, measured in our model by the realized reproductive rates, are each equal to unity. A comparison with previous studies suggests a unifying rule for the evolution of dispersal: the dispersal rates which permit the spatial homogenization of fitnesses are ESSs. This condition provides new insight into the evolutionary stability of source-sink systems. It also supports the hypothesis that immigrants have adapted demographic strategies, rather than the hypothesis that dispersal is costly and immigrants are at a disavantage compared with residents.
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    URL: http://dx.doi.org/10.1007/s10682-997-1516-z
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    Tree-thinking and nemertean systematics, with a systematization of the Eureptantia (1997)
    Springer
    Hydrobiologia 365 (1997), S. 33-46 
    Details
    ISSN: 1573-5117
    Keywords: Phylogeny ; cladistics ; taxonomy ; systematics ; classification ; evolution ; history ; chronicle ; Nemertea ; Hoplonemertea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I review how some influential nemertean systematistshave perceived and illustrated phylogenetic trees andargue that the nineteenth century nemerteantaxonomists still influence many contemporarynemertean taxonomists to a high degree. By showing hownineteenth century systematics differs from moremodern views on trees, I hope to convey the advantagesof a cladistic approach to tree-thinking and nemerteansystematics. Furthermore I propose a systematizationof the Eureptantia that illustrates the cladisticapproach to tree-thinking but, more importantly, isalso a better representation of eureptantic phylogenythan previous classifications.
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    URL: http://dx.doi.org/10.1023/A:1003174326275
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    No Evidence for a Y Chromosomal Effect on Alternative Behavioral Strategies in Mice (1997)
    Springer
    Behavior genetics 27 (1997), S. 477-482 
    Details
    ISSN: 1573-3297
    Keywords: Aggression ; nest-building behavior ; wild house mice ; behavioral strategies ; bidirectional selection ; Y chromosome ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract This study takes the first step toward testing a Y chromosomal effect on both aggression and thermoregulatory nest-building behavior in mouse lines either bidirecrionally selected for short (SAL) and long (LAL) attack latency or high (HIGH) and low (LOW) nest-building behavior. Using reciprocal crosses between SAL and LAL, and between HIGH and LOW, we found no indications for Y chromosomal effects on thermoregulatory nest-building behavior. As for aggression, we confirmed earlier studies on SAL and LAL, i.e., the origin of the Y chromosome influences attack latency, i.e., aggression. However, we did not find indications for a Y chromosomal effect on aggression in the HIGH and LOW lines. Since aggression and nest-building behavior have been shown to be characteristic parameters of two fundamentally different behavioral strategies, the present data underline the improbability of Y chromosomal genes underlying the genetic architecture of alternative behavioral strategies.
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    URL: http://dx.doi.org/10.1023/A:1025678517986
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    Simple standard procedure for the routine determination of organic matter in marine sediment (1997)
    Springer
    Hydrobiologia 345 (1997), S. 87-94 
    Details
    ISSN: 1573-5117
    Keywords: sediments ; method ; organic matter ; difference-on-ignition ; weight ; temperature ; time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For the routine determination of organic matter inmarine sediment, a rough estimate is often obtained bymeasuring the loss of weight on ignition(Difference-On-Ignition method: D.O.I.). This D.O.I. is to beused in ecological studies where organic material insediment is used as an environmental variable amongothers. A review of papers using this method showed agreat variability within conditions used. Theseconditions are generally used without accuratejustification. We propose a simple standard procedurebased on grain-size fraction of sediment to determineoptimal temperature and time of ignition, and theinfluence of the sample weight. The method proposed, using the loss of weight on ignition, will give thesame accuracy in measurements of organic matter inmarine sediments.
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    URL: http://dx.doi.org/10.1023/A:1002902626798
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    The effect of temperature, and food quantity and quality on the growth and development rates in laboratory-cultured copepods and cladocerans from a Sri Lankan reservoir (1997)
    Springer
    Hydrobiologia 350 (1997), S. 131-144 
    Details
    ISSN: 1573-5117
    Keywords: microcrustacean zooplankton ; tropical limnology ; laboratory cultures ; growth ; development rates ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Length growth, instar durations, fecundity and mortality rates of fivespecies of microcrustacean zooplankton from a tropical reservoir weremeasured in relation to food quantity and temperature in laboratorycultures. Three cladocerans (Ceriodaphnia cornuta, Moina micrura,Diaphanosoma excisum), one calanoid copepod (Heliodiaptomus viduus), and onecyclopoid copepod (Mesocyclops thermocyclopoides) were studied. Filteredseston (45 µm mesh) from a local pond was used for food. Two foodconcentrations were employed: (1) 10 µg chlorophyll l−1(ca 0.25 mg Cl−1), and (2) 50 µg chlorophylll−1 (ca 1.25 mg C l−1). Food levels and watertemperature (22.5, 27.5, and 32.5 °C) used, roughly covered the rangesfound in the reservoir. Although all the three growth parameters were oftenaffected to some degree by temperature and food, the quantitative responseof the species differed. Also, the species reacted differently to the threepossible interactions (i.e. food × temperature,food × instar, andtemperature × instar). This contributed to the overalldifferences in the species responses. For the cladocerans, instar durationswere always affected by temperature. The food did not affect the durationtime of the adults and that of the combined juvenile instars, the latterexcept in one case significantly. For the two copepods food level affectedthe duration times of naupliar and copepodite instars, but the effect oftemperature was only significant for H. viduus. The development timesobserved for H. viduus were extraordinary long compared with values reportedin the literature for other tropical calanoids. This suggests that foodconditions in our culture were adversely affecting its growth rates.
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    Energy content of rotifers (Brachionus plicatilis and Brachionus rotundiformis) in relation to temperature (1997)
    Springer
    Hydrobiologia 358 (1997), S. 83-87 
    Details
    ISSN: 1573-5117
    Keywords: rotifers ; Brachionus plicatilis ; Brachionus rotundiformis ; energy content ; chemicalcomposition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature on the chemical composition (carbon, nitrogenand ash content) and the energy content of the rotifers Brachionusplicatilis and Brachionus rotundiformis (formerly B. plicatilis L- andS-type respectively) was examined in experimental populations. Dry weightand carbon, nitrogen and hydrogen content remained practically unchanged inthe 20–35 °C range in B. rotundiformis, while in B.plicatilis the dry weight decreased slightly with increasing temperaturefrom 15 ° to 35 °C. Nevertheless, themajor source of variation was the fecundity status of the populations. Onthe other hand, B. rotundiformis showed higher energy content (joules per mgof dry matter) than B. plicatilis. This difference in energy content was dueto the different ash content because the organic matter of both species hadthe same energy content, as well as the same basic biomass composition.
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    Seasonal and spatial patterns in phytoplankton photosynthetic parameters in a tidal freshwater river (1997)
    Springer
    Hydrobiologia 364 (1997), S. 199-208 
    Details
    ISSN: 1573-5117
    Keywords: Phytoplankton ; photosynthesis ; light ; temperature ; tidal freshwater ; irradiance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic response to irradiance wasquantified for phytoplankton from the tidalfreshwater Potomac River biweekly to monthly over aperiod of six years. Samples were collected from twoshallow embayments and portions of the deeper rivermainstem. Photosynthetic rate was measured in thelaboratory at in situ temperature over a range ofirradiance levels and photosynthetic parameters werecalculated using nonlinear regression.PB max,the maximum photosynthetic ratestandardized to chlorophyll a, increased withtemperature up to 25 °C with a Q10 of 2.02. Above 25 °C, PB max was essentiallyconstant with temperature. Lesser correlationbetween PB max and ambient irradiance couldbe explained by the correlation of irradiance withtemperature. α, the slope of the P–I curve atlow light, was correlated with both ambientirradiance and temperature. Highest α valueswere found in late summer when high temperature andintermediate ambient irradiance were observed. Spring and early summer were characterized by lowα. Despite low light penetration, Ik andα values were indicative of sun limitationpossibly due to intermittent high light levelsexperienced during mixing. Ik showed a clearseasonal trend directly related to days from summersolstice. Spatial patterns were minimal except thatIk was consistently lower in one shallowembayment than in the other two areas. Seasonalpatterns in photosynthetic parameters correspondedroughly to changes from a spring diatom populationto summer cyanobacterial assemblage.
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    Comparative mapping of Xp22 genes in hominoids – evolutionary linear instability of their Y homologues (1997)
    Springer
    Chromosome research 5 (1997), S. 167-176 
    Details
    ISSN: 1573-6849
    Keywords: comparative mapping ; evolution ; hominoids ; X–Y homologous genes ; Y chromosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several genes located within or proximal to the human PAR in Xp22 have homologues on the Y chromosome and escape, or partly escape, inactivation. To study the evolution of Xp22 genes and their Y homologues, we applied multicolour fluorescence in situ hybridization (FISH) to comparatively map DNA probes for the genes ANT3, XG, ARSD, ARSE (CDPX), PRK, STS, KAL and AMEL to prometaphase chromosomes of the human species and hominoid apes. We demonstrate that the genes residing proximal to the PAR have a highly conserved order on the higher primate X chromosomes but show considerable rearrangements on the Y chromosomes of hominoids. These rearrangements cannot be traced back to a simple model involving only a single or a few evolutionary events. The linear instability of the Y chromosomes gives some insight into the evolutionary isolation of large parts of the Y chromosomes and thus might reflect the isolated evolutionary history of the primate species over millions of years.
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    URL: http://dx.doi.org/10.1023/A:1018490713273
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    Comparative analysis on the distribution of heterochromatin in Citrus, Poncirus and Fortunella chromosomes (1997)
    Springer
    Chromosome research 5 (1997), S. 86-92 
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    ISSN: 1573-6849
    Keywords: chromosome banding ; citrus ; fluorochrome ; heterochromatin ; karyotype ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Double fluorochrome staining with chromomycin A3 (CMA) and 4′-6-diamidino-2-phenylindole (DAPI) was used to characterize and compare the distribution of constitutive heterochromatin along chromosomes of Citrus, Poncirus and Fortunella species. Only CMA-positive bands were distinguishable in metaphase chromosomes. Preferential distribution of heterochromatin in terminal regions, mainly of the long arm, and centromeric regions of a few long chromosomes was a common feature of these genera. Heteromorphism between possible homologous chromosomes was present in the majority of species. Citrus and Poncirus revealed some remarkably uniform chromosomes without any intensively fluorescing region, whereas Fortunella cultivars were differentiated by the presence of CMA bands in all chromosomes. Through measurements assisted by a computer, amounts of CMA-positive regions were shown to be highest in Fortunella. Similarities between Citrus and Poncirus suggest little heterochromatin diversification among karyotypes of these genera, whereas Fortunella, with higher amounts and more homogenous distribution of heterochromatin, is more divergent.
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    URL: http://dx.doi.org/10.1023/A:1018409922843
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    Male-biased distribution of the human Y chromosomal genes SRY and ZFY in the lizard Calotes versicolor, which lacks sex chromosomes and temperature-dependent sex determination (1997)
    Springer
    Chromosome research 5 (1997), S. 413-419 
    Details
    ISSN: 1573-6849
    Keywords: evolution ; reptiles ; sex determination ; SRY ; ZFY
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the present investigation on the lizard Calotes versicolor, which lacks temperature-dependent sex determination, all the conventional cytological techniques used failed to resolve a distinguishable pair of sex chromosomes. However, probing of the genome with the human Y-linked genes SRY and ZFY showed sex-specific bias in their distribution. While the SRY probe hybridized to all the males, more than half of the females examined did not show any hybridization. ZFY hybridized to both the sexes, giving two bands; one was common to all the individuals of both sexes, but the other, of the lower molecular length, occurred in all the males but in less than 50% of females. This predominantly male-specific band is named AMF. The SRY-positive females were also positive for the AMF of ZFY. As positive as well as negative females were fertile and none of the males lacked SRY, it appears that SRY is essential for males only and that both the genes are syntenic in this species. This report raises interesting possibilities on the differentiation of the sex chromosomes in C. versicolor and evolution of SRY/ZFY on the Y chromosome of eutherian mammals through the ancestral group(s) that harbour sex-independent SRY- and ZFY-related genes.
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    URL: http://dx.doi.org/10.1023/A:1018452526903
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    Rice genetic resources: history, conservation, investigative characterization and use in Japan (1997)
    Springer
    Plant molecular biology 35 (1997), S. 69-77 
    Details
    ISSN: 1573-5028
    Keywords: rice ; wild rice ; Oryza spp. ; evolution ; conservation ; evaluation ; utilization ; germplasm ; genetic resources ; genebank
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rice has been grown in Japan for about 3000 years. Although both japonica and indica varieties have been grown in Japan, now japonica rices are grown. Japanese rice breeding has used an ecological breeding approach. While emphasis in rice breeding in the 1940's and 1950's focussed on yield in recent decades quality has been of major importance. Consumer preference and name recognition of high quality varieties, such as Koshihikari, has resulted in slow acceptance of new varieties. Rice germplasm was systematically collected throughout Japan between 1962 and 1963. Subsequent acquisition and collecting, in Japan and other countries, has resulted in 28,000 accessions being conserved in the National Genebank, based at the National institute of Agrobiological Resources (NIAR). Research on genetic diversity of rice using a range of techniques, for example esterase isozymes, has revealed clinal variation in rice radiating from the center of diversity of rice in and around southwest China. Newly found genes in traditional rice germplasm, such as genes for non-elongating mesocotyl, are now routinely identified on the rice genome. Pioneering studies on eco-genetic differentiation of species in the genus Oryza in Japan has revealed much about the complex genepool for which rice evolved. Pest and disease resistance sources, particularly to blast, bacterial blight and brown plant hopper, from many countries have been incorporated into Japanese varieties. Cold tolerance at the booting stage was found in the Indonesian variety Silewah. In the future in characterisation of rice germplasm and interaction between rice germplasm specialists and rice molecular scientists, both in Japan and internationally, will be corner stones to securing rice genetic diversity and rice improvement in the next century.
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    URL: http://dx.doi.org/10.1023/A:1005784431759
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    Analysis of multiple copies of geminiviral DNA in the genome of four closely related Nicotiana species suggest a unique integration event (1997)
    Springer
    Plant molecular biology 35 (1997), S. 313-321 
    Details
    ISSN: 1573-5028
    Keywords: integration ; geminivirus ; plant genomes ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously, we discovered multiple direct repeats of geminivirus-related DNA (GRD) sequences clustered at a single chromosomal position in Nicotiana tabacum (tobacco). Here we show that, in addition to tobacco, multiple copies of these elements occur in the genomes of three related Nicotiana species, all in the section Tomentosae: N. tomentosiformis, N. tomentosa and N. kawakamii, but not in 9 other more distantly related Nicotiana species, nor in various other solanaceous and non-solanaecous plants. DNA sequence analysis of 18 GRD copies reveal 4 distinct, but highly related, sub-families: GRD5, GRD3 and GRD53 in tobacco; GRD5 in N. tomentosiformis and N. kawakamii; and GRD2 in N. tomentosa. In addition to novel sequences, all elements share significant but varying lengths of DNA sequence similarity with the geminiviral replication origin plus the adjacent rep gene. There is extended sequence similarity to REP protein at the deduced amino acid sequence level, including motifs associated with other rolling circle replication proteins. Our data suggest that all GRD elements descend from a unique geminiviral integration event, most likely in a common ancestor of these Tomentosae species.
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    URL: http://dx.doi.org/10.1023/A:1005885200550
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    Mitochondrial Dehydrogenases in Different Taxa of Tetrahymena: Effect of Insulin (1997)
    Springer
    Bioscience reports 17 (1997), S. 529-535 
    Details
    ISSN: 1573-4935
    Keywords: Mitochondria ; mt-dehydrogenase ; evolution ; insulin ; hormonal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mitochondrial dehydrogenase activity was measured in seven taxa of Tetrahymena (T. pyriformis G1, T. hegewishi, T. malaccensis, T. pigmentosa, T. shapiro, T. thermophila CU-399, T. thermophila MS-1). Enzyme activity was different in the taxa investigated. Insulin reduced enzyme activity in six of the seven taxa studied. The duration of activity reduction was relatively long (5–10 min.) in most of the cases, and in T. hegewishi this lasted up to the end of the measurements (30 min.). There was no interrelation between the basic dehydrogenase activity of the taxon and the effect of insulin. There was also no correlation between the degree of relationship (of the taxa) and the dehydrogenase profile after insulin treatment.
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    Imprinting Effects of Proline Containing Dipeptides (Proline-Glycine, Proline-Leucine, Proline-Valine and Their Retro Variants) in Tetrahymena. Evolutionary Conclusions (1997)
    Springer
    Bioscience reports 17 (1997), S. 537-542 
    Details
    ISSN: 1573-4935
    Keywords: Tetrahymena ; evolution ; hormones ; peptides ; signal molecule ; imprinting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Proline-glycine, proline-leucine and proline-valine dipeptides and their retro variants were used in the experiments to study the effects of pretreatment (imprinting) in Tetrahymena, by investigating fluorescein isothiocyanate (FITC)-conjugated peptide binding. The protozoan organism could differentiate between the proline-dipeptides containing different partner amino-acids and between the dipeptides having the amino acids in reversed positions. The effect of imprinting was positive or negative and this was dependent on the type of the partner amino acid and on its position. Pro-Gly and Pro-Leu induced positive imprinting (elevated FITC-dipeptide binding) and Pro-Val induced negative imprinting (decrease of FITC-peptide binding). There was positive imprinting induction in two cases for the retro FITC-peptide and in one case for the FITC-conjugate of the imprinter peptide itself. The highest positive imprinting (almost 60% increase) was induced by Pro-Gly for FITC-Gly-Pro. Considering earlier—chemotaxis—experiments, the results of the present—binding—studies run parallel with the physiological effects. The experiments call attention to the sharp differentiating ability of small peptides at a unicellular level, that could have some role in the selection of molecules for hormone formation, during evolution.
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    Modification of Clay Forms by Tufted Capuchins (Cebus apella) (1997)
    Springer
    International journal of primatology 18 (1997), S. 455-467 
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    ISSN: 1573-8604
    Keywords: Cebus ; Homo ; evolution ; Paleolithic art ; tool-use
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined modification of clay forms by tufted capuchins (Cebus apella) by presenting groups of subjects with clay, paint, stones, leaves, and sticks. In Experiment 1, 7 of 10 subjects reshaped portable forms with their hands and with stones, and decorated them with leaves and paint. In Experiment 2, 9 subjects marked clay slabs manually and with stick and stone tools. The manipulative propensities of Cebus can help us to understand psychological processes that underlie artistic expression in Homo and Pan.
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    Factors affecting germination of oospores of Peronospora viciae f.sp. pisi in vitro (1997)
    Springer
    European journal of plant pathology 103 (1997), S. 573-580 
    Details
    ISSN: 1573-8469
    Keywords: Pisum sativum ; host plant exudates ; light ; temperature ; infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of host plant exudates, light and temperature on germination of oospores of Peronospora viciae f.sp. pisi in vitro were investigated. Seed and root exudates did not increase percentage germination, whereas light inhibited germination. The first germ tubes appeared after 4, 7, and 14 days of incubation at 15, 10 and 5 °C, respectively. The eventual level of germination was highest and had similar values at 5 and 10 °C. At 20 °C germination was poor and at 25 °C no germination was observed. Oospores placed on membrane filters were incubated on soil. When oospores were retrieved from the membrane filters after six days and placed in water at 10 °C, they germinated within 2 days. On soil significantly less oospores germinated than in water. Germinability of oospores stored in the dark at 5 or 20 °C at 30 or 76% RH was studied over a two-year period. Germinability generally increased over time, but fluctuations were observed indicating the occurrence of secondary dormancy. Time courses of germinability were generally similar for oospores stored at several temperatures and humidities. No effect of light on time course of germinability was found when oospores were exposed to alternating light-dark periods or stored in continuous dark for 140 days. Percentage germination observed in a germination assay was correlated with percentage infection determined in a bioassay.
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    URL: http://dx.doi.org/10.1023/A:1008607100742
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    To mark the host or the patch: Decisions of a parasitoid searching for concealed host larvae (1997)
    Springer
    Evolutionary ecology 11 (1997), S. 145-168 
    Details
    ISSN: 1573-8477
    Keywords: evolution ; Halticoptera laevigata ; host-marking pheromone ; parasitoids ; patch mark ; Tephritidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We found evidence for patch marking in the parasitic wasp Halticoptera laevigata (Hymenoptera: Pteromalidae) foraging for concealed hosts. Wasps attack larvae of the fruit fly Myoleja lucida (Diptera: Tephritidae) in fruits of honeysuckle. A special feature of this host-parasitoid system is the limited food supply of a patch (i.e. a fruit of honeysuckle), which allows the successful development of only a single host fly larva. Females of the parasitoid H. laevigata were found to mark the host patch with a pheromone and to abandon the patch following oviposition into a single host larva. Field data revealed that eggs of the parasitoid were spread out evenly among infested patches, with several larvae of the host fly left unparasitized in those patches that contained more than one host. Since many parasitic insects mark the parasitized host after oviposition, we assumed host marking to be the ancestral character state and studied the patch-marking behaviour of H. laevigata as a derived character state as an alternative foraging strategy. We used stochastic dynamic modelling to investigate under what conditions mutant (patch) markers would be able to invade a population of normal (larval) markers. The models suggested that, under a variety of conditions, wasps marking the patch obtained higher fitness than wasps only marking the larva. Consequently, the results from our model predict the evolution of the patch-marking behaviour found in the empirical investigation. Finally, we discuss alternative pathways to the evolution of patch marking and point out under what circumstances the evolution of a patch-marking behaviour can generally be expected.
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    URL: http://dx.doi.org/10.1023/A:1018495731755
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    Evolution of flower shape inVeroniceae (Scrophulariaceae) (1997)
    Springer
    Plant systematics and evolution 205 (1997), S. 1-25 
    Details
    ISSN: 1615-6110
    Keywords: Veroniceae ; Scrophulariaceae ; Flower shape ; flower development ; quantitative developmental character ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Floral evolution in the tribeVeroniceae was examined using phylogenetic analysis combining 24 adult morphology and chromosome number characters with 22 qualitative and quantitative floral development characters. Taxa sampled included nine species ofVeroniceae and as an outgroup one species each ofDigitaleae andVerbasceae. Veronica, Besseya, andSynthyris formed one clade, subtended byPseudolysimachion and then by theHebe group;Veronicastrum orWulfenia represent the basal-most branch of the tribe. The ancestral flowers of theVeroniceae may have been small with moderately short corolla tubes and lobes; long corolla tubes arose four times in the tribe and large corolla lobes twice.
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    URL: http://dx.doi.org/10.1007/BF00982795
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    Floral divergence and convergence in the genusPelargonium (Geraniaceae) in southern Africa: Ecological and evolutionary considerations (1997)
    Springer
    Plant systematics and evolution 208 (1997), S. 71-97 
    Details
    ISSN: 1615-6110
    Keywords: Geraniaceae ; Pelargonium ; Bees ; beeflies ; birds ; butterflies ; long-proboscid flies ; convergence ; evolution ; floral ecology ; pollination ; pollination guilds ; pollination syndromes ; Southern Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on field observations and a survey of the available literature, the functional and evolutionary significance of floral characters ofPelargonium is investigated in relation to a recent infrageneric re-classification. Most of the 208Pelargonium taxa (recognized as species, subspecies or varieties) involved show bee and long-proboscid hovering fly pollination syndromes (about 60% and 25%, respectively), only 7% of the taxa are pollinated by butterflies, some 2 to 4% by hawkmoths and presumably 1% by birds. The heterogeneity ofPelargonium in terms of structural blossom types and pollination syndromes indicates an independent and repeated evolution of convergent flower morphs in the genus and even in sections.
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    URL: http://dx.doi.org/10.1007/BF00986083
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    Hybridization and evolution inCardamine (Brassicaceae) at Urnerboden, Central Switzerland: Biosystematic and molecular evidence (1997)
    Springer
    Plant systematics and evolution 204 (1997), S. 233-256 
    Details
    ISSN: 1615-6110
    Keywords: Brassicaceae ; Cardamine amara ; C. ×insueta ; C. rivularis ; C. schulzii ; Hybridization ; evolution ; amphiploidy ; introgression ; cpDNA ; isozymes ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hybridization between two diploid (2n = 2x = 16) species ofBrassicaceae, Cardamine rivularis andC. amara, at Urnerboden, Central Switzerland, resulted in the rather unusual triploid hybridC. insueta (2n = 3x = 24), and later on in the amphiploidC. schulzii (2n = 6x = 48). The hybrid and the neopolyploid species colonized successfully some man-made biotopes. Plants ofC. insueta are mostly functional females with non-dehiscent anthers, but true hermaphrodite individuals with partly sterile pollen grains also occur within the population. Analyses of cpDNA and nuclear DNA permitted to establish the parentage of the hybrid: the maternal parent which contributed unreduced egg cells proved to beC. rivularis whereas the normally reduced pollen originated fromC. amara. The pronounced genetic variability inC. insueta revealed by isozyme and RAPD analyses, at variance with the polarized segregation, heterogamy and strong vegetative reproduction of the hybrid, is possibly influenced by recurrent formation ofC. insueta which party results from backcrosses betweenC. insueta andC. rivularis but may also proceed by other pathways. The amphiploidCardamine schulzii has normally developed anthers but its pollen is sometimes highly sterile. The surprisingly uniform genetic make-up of the new amphiploid species might be related to its possible monotopic origin and/or young phylogenetic age but should be further assessed. Site management seems to be very important to a further development of hybridogenous populations and their parent species. In conclusion, the evolution at Urnerboden is discussed in the context of the traditional concept of multiple plant origins.
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    URL: http://dx.doi.org/10.1007/BF00989208
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    Micellization of triblock copoly(ethyleneoxide/tetrahydrofuran/ethylene oxide) (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 467-473 
    Details
    ISSN: 1435-1536
    Keywords: Key words Block copolymers ; micelle ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The association behaviour of triblock copoly(ethylene oxide/tetrahydrofuran/ethylene oxide), in particular E100T27E100, in aqueous solutions has been investigated by means of static and dynamic light scattering, nuclear magnetic reso-nance (NMR) and surface tension techniques. On raising the polymer concentration at room temperature, the copolymer aggregates to form micelles with an aggregation number of about 105 (R G, mic≈15 nm and R H, mic≈13 nm, as revealed by light scattering and FT-PGSE NMR measurements, respectively). The micelles are kinetically quite stable, the micellar lifetime is shown to be more than 1 h. The residence time of a single unimer in a micelle is more than 140 ms. The apparent radius of gyration R G, mic is fairly independent of concentration, but large effects are observed on varying the temperature. Raising the temperature initially results in an increase of the apparent micellar size, followed by a maximum at an intermediate temperature (≈45 °C). At higher temperatures a contraction of the micelles is observed. The shape of the micelles also appear to vary in this temperature interval. The interactions responsible for these phenomena are discussed in terms of, e.g., the temperature-dependent solubility of the alkylene oxide segments in water and polydispersity effects.
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    URL: http://dx.doi.org/10.1007/s003960050105
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    Mineralisation of nitrogen from an incorporated catch crop at low temperatures: experiment and simulation (1997)
    Springer
    Plant and soil 188 (1997), S. 211-219 
    Details
    ISSN: 1573-5036
    Keywords: catch crop ; mineralisation ; nitrogen ; simulation model ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The release of nitrogen from incorporated catch crop material in winter is strongly influenced by soil temperatures. A laboratory experiment was carried out to investigate this influence in the range of 1-15 °C. Samples of sandy soil or a mixture of sandy soil with rye shoots were incubated at 1-5-10-15 °C, and samples of sandy soil with rye roots were incubated at 5-10-15 °C. Concentrations of Nmin (NH4 +-N and NO3 --N) were measured after 0-1-2-4-7-10 weeks for the sandy soil and the sandy soil:rye shoot mixture, and after 0-2-7-10 weeks for the sandy soil:rye root mixture. At 1 °C, 20% of total organic N in the crop material had been mineralised after ten weeks, indicating that mineralisation at low temperatures is not negligible. Maximum mineralisation occurred at 15 °C; after ten weeks, it was 39% of total applied organic nitrogen from shoot and 35% from root material. The time course of mineralisation was calculated using an exponential decay function. It was found that the influence of temperature in the range 1-15 °C could be described by the Arrhenius equation, stating a linear increase of ln(k) with T-1, k being the relative mineralisation rate in day-1 and T the temperature (°C). A simulation model was developed in which decomposition, mineralisation and nitrification were modelled as one step processes, following first order kinetics. The relative decomposition rate was influenced by soil temperature and soil moisture content, and the mineralisation of N was calculated from the decomposition of C, the C to N ratio of the catch crop material and the C to N ratio of the microbial biomass. The model was validated first with the results of the experiment. The model was further validated with the results of an independent field experiment, with temperatures fluctuating between 3 and 20 °C. The simulated time course of mineralisation differed significantly from the experimental values, due to an underestimation of the mineralisation during the first weeks of incubation.
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    URL: http://dx.doi.org/10.1023/A:1004255102840
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    Morphology and tissue quality of seedling root systems of Pinus taeda and Pinus ponderosa as affected by varying CO2, temperature, and nitrogen (1997)
    Springer
    Plant and soil 195 (1997), S. 107-119 
    Details
    ISSN: 1573-5036
    Keywords: carbohydrates ; carbon dioxide ; nitrogen ; nutrients ; roots ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rising atmospheric carbon dioxide, nitrogen deposition and warmer temperatures may alter the quantity and quality of plant-derived organic matter available to soil biota, potentially altering rates of belowground herbivory and decomposition. Our objective was to simulate future growth conditions for an early successional (loblolly) and late successional (ponderosa) species of pine to determine if the physical and chemical properties of the root systems would change. Seedlings were grown for 160 days in greenhouses at the Duke University Phytotron at 35 or 70 Pa CO2 partial pressure, ambient or ambient + 5 °C temperature, and 1 or 5 mMNH4O3. Roots from harvested seedlings were analyzed for changes in surface area, specific root length, mass, total nonstructural carbohydrates (TNC), and concentrations of macro-nutrients. Surface area increased in both species under elevated CO2, due primarily to increases in root length, and this response was greatest (+138%) in loblolly pine at high temperature. Specific root length decreased in loblolly pine at elevated CO2 but increases in mass more than compensated for this, resulting in net increases in total length. TNC was unaffected and nutrient concentrations decreased only slightly at elevated CO2, possibly from anatomical changes to the root tissues. We conclude that future growth conditions will enhance soil exploration by some species of pine, but root carbohydrate levels and nutrient concentrations will not be greatly affected, leaving rates of root herbivory and decomposition unaltered.
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    URL: http://dx.doi.org/10.1023/A:1004291430748
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    Temperature-induced alteration to root longevity in Lolium perenne (1997)
    Springer
    Plant and soil 190 (1997), S. 87-90 
    Details
    ISSN: 1573-5036
    Keywords: minirhizotron ; root longevity ; root mortality ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The production and mortality of roots is an important factor determining nutrient and carbon fluxes in terrestrial ecosystems. However, the effect of temperature on the longevity of roots is not understood. In this study the impact of changes in temperature on the longevity of Lolium perenne roots was determined. Plants were grown at 15 °C, 21 °C and 27 °C and their roots observed using a minirhizotron system. Major effects of temperature were measured with large reductions in root longevity occurring at higher temperatures. The implications of these data are discussed.
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    URL: http://dx.doi.org/10.1023/A:1004298804353
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    Environmental control for the large-scale production of plants through in vitro techniques (1997)
    Springer
    Plant cell, tissue and organ culture 51 (1997), S. 49-56 
    Details
    ISSN: 1573-5044
    Keywords: CO2 enrichment ; gas exchange ; in vitro environment ; light ; photoautotrophic micropropagation ; relative humidity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leafy or chlorophyllous explants of a number of plant species currently micropropagated have been found to have high photosynthetic ability. Their growth and development have been promoted on sugar-free medium rather than on sugar-containing medium, provided that the environmental factors, such as CO2 concentration, light intensity and relative humidity, are controlled for promoting photosynthesis and transpiration of explants/shoots/plantlets in vitro. Thus, environmental control is essential for promoting photosynthetic growth and development of in vitro plantlets. Several types of sugar-free (photoautotrophic) culture systems for large-scale micropropagation of plants have been developed. Advantages of sugar-free over conventional (heterotrophic or photomixotrophic) micropropagation systems are as follows: growth and development of plantlets in vitro are faster and more uniform, plantlets in vitro have less physiological and morphological disorders, biological contamination in vitro is less, plantlets have a higher percentage of survival during acclimatization ex vitro, and larger culture vessels could be used because of less biological contamination. Hence, production costs could be reduced and plant quality could be improved significantly with photoautotrophic micropropagation. Methods for the measurement and control of in vitro environments and the beneficial effects of environmental control on photosynthetic growth, development, and morphogenesis in large-scale production of micropropagated plantlets are presented.
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    URL: http://dx.doi.org/10.1023/A:1005809518371
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    Fruit component analysis of south Pacific coconut palm populations (1997)
    Springer
    Genetic resources and crop evolution 44 (1997), S. 327-335 
    Details
    ISSN: 1573-5109
    Keywords: Cocos nucifera ; diversity ; evolution ; germplasm ; genetic resources ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The south Pacific region contains a large genetic resource for the genetic improvement of coconut palms (Cocos nucifera L.). A study of the diversity in the species was made during 1992/3 using fruit component analysis on a representative sample from 29 distinct south Pacific populations in order to characterise the germplasm present in the region. A large diversity in fruit morphology was found that ranged from populations exhibiting wild-type characters in central Pacific to populations displaying domesticated characteristics in Rennell Island, the Sikaiana Islands, the Marquesas Islands, and in Papua New Guinea. Many populations exhibited fruit characteristics intermediate between the two, which were thought to have arisen due to introgressive hybridisation between the wild and domesticated populations. Continuous variation in fruit morphology was found in these populations, and cluster analysis arbitrarily divided the continuum into discrete groups which were consistent with geographic affinities. Groups were defined in Melanesia, Western Polynesia and Eastern Polynesia. The continuum displayed clinal variation from populations with small fruit and low husk content in the west to large fruit and more husk in the east of the region. The wild and domesticated populations were found in disjunct pockets throughout the area, and did not form part of the clines. Most populations consisted of a wide range of fruit morphology, from individuals expressing wild-type characters to those with domestic-type characters. The occurrence of both wild and domesticated populations within the clinal variation indicates that further exploration should be made to determine the presence of other potentially useful populations. While this activity is proceeding, collection and conservation can proceed using the classification already defined.
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    Phylogeny of the Acipenseriformes: cytogenetic and molecular approaches (1997)
    Springer
    Environmental biology of fishes 48 (1997), S. 127-155 
    Details
    ISSN: 1573-5133
    Keywords: sturgeon ; paddlefish ; Huso ; Acipenser ; Scaphirhynchus ; Pseudoscaphirhynchus ; Polyodon ; Psephurus ; karyotype ; chromosome ; macrochromosome ; microchromosome ; genome ; DNA content ; 18S rRNA gene ; cytochrome ; 12S mtrRNA gene ; 16s mtrRNA gene ; rate of molecular evolution ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The review of the data on karyology and DNA content in Acipenseriformes shows that both extant families, the Polyodontidae and Acipenseridae, originated from a tetraploid ancestor which probably had a karyotype consisting of 120 macro- and microchromosomes and DNA content of about 3.2–3.8 pg per nucleus. The tetraploidization of the presumed 60-chromosome ancestor seems to have occurred at an early time of evolution of the group. The divergence of the Acipenseridae into Scaphirhyninae and Acipenserinae occurred without polyploidization. Within the genus Acipenser, polyploidization was one of the main genetic mechanisms of speciation by which 8n and 16n-ploid species were formed. Individual gene trees constructed for sequenced partial fragments of the 18S rRNA (230 base pairs, bp), 12S rRNA (185 bp), 16S rRNA (316 bp), and cytochrome b (270 bp) genes of two Eurasian (A. baerii and A. ruthenus) and two American (A. transmontanus and A. medirostris) species of Acipenser, Huso dauricus, Pseudoscaphirhynchus kaufmanni, Scaphirhynchus albus, and Polyodon spathula showed a low level of resolution; the analysis of a combined set of data for the four genes, however, gave better resolution. Our phylogeny based on molecular analysis had two major departures from existing morphological hypotheses: Huso dauricus is a sister-species to Acipenser instead of being basal to all acipenseriforms, and Scaphirhynchus and Pseudoscaphirhynchus do not form a monophyletic group. The phylogenetic tree constructed for the cytochrome b gene fragments (with inclusion of 7 additional species of Acipenser) supported the conclusion that octoploid species appeared at least three times within Acipenser.
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    Changes in lipid class and fatty acid composition during development in pike (Esox lucius L) eggs and larvae (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 381-393 
    Details
    ISSN: 1573-5168
    Keywords: pike ; eggs ; larvae ; embryonic development ; fatty acid ; lipid class ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To establish the changes which occur during embryogenesis and early larval development, eggs, yolk sac larvae and swim-up larvae of pike were examined for lipid class and fatty acid composition. At a water temperature of 15.5°C, the embryonic phase was short (6 days) and characterized by a 41.3% decline in the lipid content of eggs, accompanied by large reductions in the amount of phosphatidylcholine (41.4% decrease), sterol esters and triacylglycerols (respectively a 41.2% decrease and a 58.1% decrease), but not phosphatidylethanolamine which increased markedly (35.6%). By the time of yolk sac absorption (7 to 11 days after fertilization) the larvae remained inactive and a limited utilization of lipids was observed. Yolk sac phosphatidylcholine was selectively incorporated into larval bodies while the levels of other lipid classes remained unchanged in the yolk. When the swim bladder was filled and the swimming stage was reached (11 days to 13 days af), the yolk was completely depleted and yolk phosphatidylcholine together with yolk triacylglycerols were catabolised. Yolk phosphatidylethanolamine and yolk sterol esters were partly incorporated into the body lipids. In the subsequent swim-up larval stage (13 to 15 days af), a steady decrease in lipids was observed (41.6%). Fluctuations in the levels of polyunsaturated fatty acids, monounsaturated fatty acids or saturated fatty acids examined from eggs or larvae were consistent with changes in lipid classes during pike development. During yolk sac absorption, pike incorporated yolk PUFA released on hydrolysis of phosphatidylcholine into the larval body. The results are discussed with reference to water temperature and in relation to the ontogenic and ecological context of pike development.
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    Seasonality of ATPase activities in crucian carp (Carassius carassius L.) heart (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 355-364 
    Details
    ISSN: 1573-5168
    Keywords: Na-K-ATPase ; pNPPase ; channel arrest ; fish heart ; thermal acclimation ; anoxia ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of seasonal acclimatization, thermal acclimation and anoxic exposure on total cation-activated ATPase and sarcolemmal Na-K-ATPase activities of crucian carp heart were measured. The total cation-activated ATPase showed a positive correlation with environmental temperature: activity was highest in mid summer and lower in early spring and late autumn. The decline of total ATPase activity during cold seasons suggests that energy consumption of the heart is reduced during the anoxic winter period by depression of ATP utilization rate. In contrast to the total ATPase activity, the activity of sarcolemmal Na-K-ATPase did not correlate strongly with environmental temperature but remained relatively constan during most of the study period. However, in late autumn when oxygen content of water is low, a prominent decline in Na-K-ATPase activity was noted. The latter finding suggests that the activity of Na-K-pump of the cardiac sarcolemma is unaffected by seasonal temperature changes but is depressed by hypoxic exposure. In accordance with this short-term anoxia (100 h) in laboratory conditions reduced Na-K-ATPase or pNPPase activities of cardiac homogenates while long-term thermal acclimation (〉4 weeks) was ineffective in this respect. The present findings suggest that cation-activated ATPases of crucian carp heart are downregulated during winter, and part of this reduction is due to anoxic depression of sarcolemmal Na-K-ATPase.
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    Effects of air pollutant-temperature interactions on mineral-N dynamics and cation leaching in reciplicate forest soil transplantation experiments (1997)
    Springer
    Biogeochemistry 39 (1997), S. 295-326 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; aluminium ; Arrhenius’ law ; calcium ; cation leaching ; climate ; ion equilibrium ; forest soil ; N-cycle ; N-deposition ; nitrification ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increased emissions of nitrogen compounds have led to atmosphericdeposition to forest soils exceeding critical loads of N overlarge parts of Europe. To determine whether the chemistry offorest soils responds to changes in throughfall chemistry, intactsoil columns were reciprocally transplanted between sites, withdifferent physical conditions, across a gradient of N and Sdeposition in Europe. The transfer of a single soil to the various sites affected itsnet nitrification. This was not simply due to the nitrificationof different levels of N deposition but was explained bydifferences in physical climates which influenced mineralizationrates. Variation in the amount of net nitrification between soiltypes at a specific site were explained largely by soil pH. Within a site all soil types showed similar trends in netnitrification over time. Seasonal changes in net nitrificationcorresponds to oscillations in temperature but variable time lagshad to be introduced to explain the relationships. WithArrhenius‘ law it was possible to approximate gross nitrificationas a function of temperature. Gross nitrification equalled netnitrification after adaptation of the microbial community oftransplanted soils to the new conditions. Time lags, andunderestimates of gross nitrification in autumn, were assumed tobe the result of increased NH 4 + availability due either tochanges in the relative rates of gross and net N transformationsor to altered soil fauna-microbial interactions combined withimproved moisture conditions. Losses of NO 3 - were associated with Ca2+and Mg2+ in non-acidified soil types and with losses ofAl3+ in the acidified soils. For single soils the ionequilibrium equation of Gaines-Thomas provided a useful approximationof Al3+ concentrations in the soil solution as a functionof the concentration of Ca2+. The between site deviationsfrom this predicted equilibrium, which existed for single soils, couldbe explained by differences in throughfall chemistry which affectedthe total ionic strength of the soil solution. The approach of reciprocally transferring soil columnshighlighted the importance of throughfall chemistry, interactingwith the effect of changes in physical climate on forest soilacidification through internal proton production, in determiningsoil solution chemistry. A framework outlining the etiology offorest die-back induced by nitrogen saturation is proposed.
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    Seasonal variation of muscle metabolic organization in rainbow trout (Oncorhynchus mykiss) (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 139-155 
    Details
    ISSN: 1573-5168
    Keywords: season ; metabolic organization ; muscle ; fish ; temperature ; lipid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examined how muscle metabolic organization varied during an annual cycle in which rainbow trout (Oncorhynchus mykiss) were held in outdoor holding ponds in which they were exposed to natural changes in temperature (range 0.2 to 15.6°C) and photoperiod. We examined the activities of glycolytic and mitochondrial enzymes in red and white muscle to evaluate whether trout enhance their capacity for lipid and carbohydrate oxidation during cold-acclimization. When assayed at habitat temperature, the enzyme activities generally increased in spring to reach a maximum in summer followed by a decrease in the fall. This led to significantly higher activities at warm than cold periods for all enzymes measured in red muscle and all but one in white muscle. The activities at 10°C provided little evidence for compensatory adjustments of aerobic capacity. Particularly in red muscle, enzyme levels at 10°C were generally lower during cold than warm periods. The variation of enzyme activities throughout the cycle was not due to changes in protein concentration, as the same responses were observed when activities were expressed per g wet mass or per mg protein. Although the aerobic capacity did not increase with cold-acclimatization, the relative capacity for lipid oxidation was higher in winter than in summer trout. In contrast, the relative capacity for aerobic glycolysis was higher in summer than in winter trout. Thus, the metabolic capacities of trout muscle undergo seasonal reorganization.
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    The role of growth in endocrine regulation of salmon smoltification (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 231-236 
    Details
    ISSN: 1573-5168
    Keywords: growth ; salmon ; smoltification ; insulin ; insulin-like growth factor I (IGF-I) ; growth hormone ; thyroxine ; photoperiod ; temperature ; nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1023/A:1007710308765
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    Biopolitics: the newest synthesis? (1997)
    Springer
    Genetica 99 (1997), S. 173-184 
    Details
    ISSN: 1573-6857
    Keywords: evolution ; genetics ; neurophysiology ; philosophy ; politics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On first impression, the disciplines of genetics and political science would appear to be unrelated. And yet, commencing more than 30 years ago, the interdisciplinary field known as Biopolitics has now taken hold. This essay traces the central thrust of the biopolitical research agenda. It describes, analyzes, and assesses how political scientists have sought to show connections between our species' genetic constitution and our species' political behavior. Important bridges between the two are the neurophysiology of the human brain and the role of evolutionary theory in charting man's adaptational political profile. The parameters of the emerging biopolitical literature raise profound policy questions, some of which are also characterized.
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    Evolutionary links between telomeres and transposable elements (1997)
    Springer
    Genetica 100 (1997), S. 73-84 
    Details
    ISSN: 1573-6857
    Keywords: evolution ; heterochromatin ; retrotransposable elements ; telomerase ; telomeres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transposable elements are abundant in the genomes of higher organisms but are usually thought to affect cells only incidentally, by transposing in or near a gene and influencing its expression. Telomeres of Drosophila chromosomes are maintained by two non-LTR retrotransposons, HeT-A and TART. These are the first transposable elements with identified roles in chromosome structure. We suggest that these elements may be evolutionarily related to telomerase; in both cases an enzyme extends the end of a chromosome by adding DNA copied from an RNA template. The evolution of transposable elements from chromosomal replication mechanisms may have occurred multiple times, although in other organisms the new products have not replaced the endogenous telomerase, as they have in Drosophila. This is somewhat reminiscent of the oncogenes that have arisen from cellular genes. Perhaps the viruses that carry oncogenes have also arisen from cellular genetic systems.
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    The evolution of Ty1-copia group retrotransposons in eukaryote genomes (1997)
    Springer
    Genetica 100 (1997), S. 185-195 
    Details
    ISSN: 1573-6857
    Keywords: biodiversity ; copia ; evolution ; genome organization ; retrotransposon ; Ty element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Ty1-copia group of LTR retrotransposons has been studied extensively in yeast and Drosophila, the organisms in which they were first discovered, and more recently in higher plant and vertebrate species. Their properties, such as copy number, sequence homogeneity, transcriptional and transpositional activity vary greatly between these different hosts. We will try to resolve these apparent discrepancies between these properties, explain any fundamental differences in the biology of the Ty1- copia group between hosts, and propose a general model for LTR retrotransposon evolution.
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    URL: http://dx.doi.org/10.1023/A:1018385713293
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    Bare-Id, a representative of a family of BARE-like elements of the barley genome (1997)
    Springer
    Genetica 100 (1997), S. 231-240 
    Details
    ISSN: 1573-6857
    Keywords: barley ; evolution ; Hordeum ; retrotransposon ; Ty1-copia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In our search for transposable elements in barley, Hordeum vulgare, we have isolated and cloned two BamHI-fragments of 4.7 and 4.2 kb in length containing very abundant DNA sequences. The 4.7 kb fragment is homologous to the extended region, including more than half of the 5′-LTR and some part of the coding domain of BARE-1, a member of copia-like retrotransposon family of barley. The 4.2 kb fragment, bearing homology to BARE-1 and the WIS-2 family isolated from wheat, is unique among studied retroelements of cereals because it consists of two inverted parts, each containing homology to the LTR and UTL of BARE-1. Functional motifs for reverse transcription, two TATA-boxes and two primer-binding sites, were found within the LTRs. The element contained within this fragment was generated by significant rearrangement of a BARE-like retrotransposon, which included inversion of the extended 5′-terminal region and deletion of the internal domain. Therefore this element is named BARE-ID (BARE-inverted, deleted). A family of BARE-like elements is amplified in the H. vulgare genome compared with wild barley species. The terminal inverted repeat of BARE-ID was used as a probe for examination of evolutionary diversity within genus Hordeum. Our data are basically in agreement with the modern classification system. However, they do not support the combination of H. vulgare and H. bulbosum into one group with the same type of genome. New data concerning the possible origin of the polyploid species, H. secalinum, confirm that retrotransposons are a useful tool for phylogenetic studies.
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    URL: http://dx.doi.org/10.1023/A:1018350100089
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    Biopolitics: the newest synthesis? (1997)
    Springer
    Genetica 99 (1997), S. 173-184 
    Details
    ISSN: 1573-6857
    Keywords: evolution ; genetics ; neurophysiology ; philosophy ; politics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On first impression, the disciplines of genetics and political science would appear to be unrelated. And yet, commencing more than 30 years ago, the interdisciplinary field known as Biopolitics has now taken hold. This essay traces the central thrust of the biopolitical research agenda. It describes, analyzes, and assesses how political scientists have sought to show connections between our species' genetic constitution and our species' political behavior. Important bridges between the two are the neurophysiology of the human brain and the role of evolutionary theory in charting man's adaptational political profile. The parameters of the emerging biopolitical literature raise profound policy questions, some of which are also characterized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259521
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    Mapping chromosomal homology between humans and the black-handed spider monkey by fluorescence in situ hybridization (1997)
    Springer
    Chromosome research 5 (1997), S. 527-536 
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    ISSN: 1573-6849
    Keywords: Ateles geoffroyi ; chromosome painting ; cytogenetics ; evolution ; phylogeny ; Platyrrhini ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We hybridized human chromosome-specific DNA probes to metaphases of the New World monkey Ateles geoffroyito map the chromosomal homology between these two species. In the haploid Ateles geoffroyi karyotype the total number of signals was 51 for the 22 human autosomal probes used. Compared with Old World monkeys, the number of translocations found in the black-handed spider monkey karyotype was quite striking. The majority of these translocations are apparently Robertsonian and no reciprocal translocations were revealed. Nine autosomal human chromosome probes (11, 13, 14, 17, 18, 19, 20, 21, 22) provided only two signals each per metaphase, but six of these were translocated to subregions of different spider monkey chromosomes. The other 13 autosomal human chromosome paints (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 16) provided fragmented signals. Three human probes (5, 8, 10) provided signals located on two pairs of spider monkey chromosomes. Four human paints (2, 3, 4, 12) provided hybridization signals on three pairs of chromosomes. Probes 6, 7, 15 provided six signals each on two pairs of chromosomes; probe 16 gave eight signals on two pairs of spider monkey chromosomes and probe 1 gave 12 signals on four pairs of chromosomes. The synteny between segments to human 18/8 appears to be an apomorphic ancestral condition for all New World monkeys. A synteny between regions homologous to human 16/10, 5/7 and 2/16 HSA is probably an apomorphic ancestral condition for all Cebidae. The syntenic association 3/15 and 4/1 is an apomorphic condition for the Atelinae.
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    Zoo-fluorescence in situ hybridization analysis of human and Indian muntjac karyotypes (Muntiacus muntjak vaginalis) reveals satellite DNA clusters at the margins of conserved syntenic segments (1997)
    Springer
    Chromosome research 5 (1997), S. 254-261 
    Details
    ISSN: 1573-6849
    Keywords: chromosome ; evolution ; comparative mapping ; Indian muntjac ; satellite DNA ; zoo-fluorescence in situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zoo-fluorescence in situ hybridization (FISH) with human whole chromosome-specific paint probes revealed extensive homoeologies between Indian muntjac (2n=6, 7 female, male) and human karyotypes (2n=46). Forty-two conserved syntenic segments, corresponding to all human chromosomes except the Y chromosome, produced a near-complete coverage of the muntjac complement and revealed margins of interspecific segmental homoeology. To test the hypothesis that interstitial satellite DNA loci, illuminated by a Chinese muntjac C5-satellite probe in Indian muntjac chromosome arms, mark ancestral fusion points (Lin CC, Sasi R, Fan YS, Chen Z-Q (1991) New evidence for tandem chromosome fusions in the karyotypic evolution of the Asian muntjacs. Chromosoma 101: 19–24), we combined Zoo-FISH with C5 satellite mapping. Twenty-six interstitial satellite DNA loci were detected in the haploid Indian muntjac genome and were found to co-localize with the margins of conserved human/Indian muntjac syntenic segments. These results were confirmed by two-colour FISH and are in accordance with the tandem fusion hypothesis for Indian muntjac chromosomes. Furthermore, conserved syntenic segment combinations detected in pig, cattle and Indian muntjac Zoo-FISH maps reveal ancestral artiodactyl chromosomes.
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    URL: http://dx.doi.org/10.1023/B:CHRO.0000032298.22346.46
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    The Ty1-copia group of retrotransposons in plants: genomic organisation, evolution, and use as molecular markers (1997)
    Springer
    Genetica 100 (1997), S. 205-217 
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    ISSN: 1573-6857
    Keywords: Ty1-copia ; retrotransposons ; retroelements ; plants ; genomic organisation ; evolution ; molecular marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genomic organisation and diversity of the Ty1-copia group retrotransposons has been investigated in several crop plants and their relatives from both dicotyledonous and monocotyledonous families, including potato ( Solanum tuberosum), faba beans ( Vicia faba), Vicia melanops, Vicia sativa, barley ( Hordeum vulgare), rye ( Secale cereale), and onion ( Allium cepa). Extreme heterogeneity in the sequence of the Ty1-copia retrotransposons from all these plants was revealed following sequence analysis of reverse transcriptase fragments. The estimated copy numbers of the Ty1-copia group retrotransposons for the genomes of S. tuberosum, L. esculentum, A. cepa, S. cereale, and V. faba is highly variable, ranging from a few hundred to approximately a million copies per genome. In situ hybridisation data from metaphase and prophase chromosomes of V. faba, S. cereale, and H. vulgare suggest that retrotransposon sequences are dispersed throughout the euchromatic regions of the genome but are almost undetectable in most heterochromatic regions. In contrast, similar data from metaphase chromosomes of A. cepa suggests that although retrotransposon sequences are dispersed throughout the euchromatic regions of the genome, they are predominantly concentrated in the terminal heterochromatin. These results are discussed in the context of the role played by the Ty1-copia group retrotransposons in the evolution of the plant genome. Lastly, the application of retrotransposon sequences as genetic markers for mapping genomes and for studying genetic biodiversity in plants is presented.
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    URL: http://dx.doi.org/10.1023/A:1018393931948
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    Old age, multiple formations or genetic plasticity? Clonal diversity in the uniparental Caucasian rock lizard, Lacerta dahli (1997)
    Springer
    Genetica 101 (1997), S. 125-130 
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    ISSN: 1573-6857
    Keywords: evolution ; Lacertadahli ; parthenogenesis ; uniparentality ; unisexuality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozyme variation at 35 gene loci is investigated in 161 specimens of the uniparental Caucasian lizard Lacerta dahli from several locations in Armenia and Georgia. All individuals are heterozygotic at 12 loci, and homozygotic at 21 loci. Variation at two loci results in five uniparental clones. One clone is widespread whereas four are geographically restricted and are represented by only one or two individuals. Because successful formation of uniparental clones is rare, and because the biparental species forming them are now allopatric, the most probable explanation for the origin of the observed clonal diversity is either mutation or recombination within the common clone. The rare clones have lower levels of enzyme activity at four loci, suggesting that these organisms may be genetically deficient. Although the evidence points to change in a pre-existing clone, the possibility of multiple origins cannot be ruled out.
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    URL: http://dx.doi.org/10.1023/A:1018392603062
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    On the origin of photosynthesis as inferred from sequence analysis (1997)
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    Photosynthesis research 51 (1997), S. 27-42 
    Details
    ISSN: 1573-5079
    Keywords: Photosystem I ; Photosystem II ; photosynthetic reaction center ; bacteriorhodopsin ; evolution ; UV-protection ; t Rhodopseudomonasviridis ; t Heliobacillus mobilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sequence alignments between membrane-spanning segments of pheophytin-quinone-type photosynthetic reaction centers, FeS-type photosynthetic reaction centers, core chlorophyll-proteins of PS II, chlorophyll t a/t b-containing antenna proteins of plants and light-harvesting complexes of purple bacteria led us to postulate a large common ancestral pigment-carrying protein with more than 10 membrane spans. Its original function as a UV-protector of the primordial cell is discussed. It is conceivable that a purely dissipative photochemistry started still in the context of the UV-protection. We suggest that mutations causing the t loss of certain porphyrin-type pigments led to the acquisition of redox cofactors and paved the way for a gradual transition from dissipative to productive photochemistry.
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    Axillary shoot proliferation of blue honeysuckle (1997)
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    Plant cell, tissue and organ culture 48 (1997), S. 195-201 
    Details
    ISSN: 1573-5044
    Keywords: cytokinins ; in vitro ; Lonicera caerulea ; minerals ; plant tissue culture ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Factors affecting axillary shoot development of blue honeysuckle in vitro were studied with two genotypes, Lonicera caerulea f. caerulea and L. caerulea f. edulis. There was a linear relationship between the concentration of N6-benzyladenine (1.1 to 17.8 μmol l−1) and the number of axillary branches produced (3 to 13 new shoots), biomass production and callus formation of the form caerulea shoot explants. The formation of second-order branches responded most strongly to the cytokinin treatments. Axillary branching was significantly lower at 24/20 °C (mean day maximum/night minimum) than at 26/20 °C. When the cultures were incubated at 28/21 °C, the number of axillary shoots produced was highest, 10.4 and 21.1 in the forms caerulea and edulis, respectively, but apical injuries were more frequent (17 in the form caerulea, 49 in the form edulis) and shoot morphology changed as compared to the shoots developed at lower temperatures. In the form edulis, the production of axillary shoots also increased by diluting the mineral nutrients of the MS medium to 75. Further dilution of minerals to 50 increased the incidence of apical shoot necrosis. It was shown that the stimulation of axillary branching by increased temperature or decreased nutrient supply was not caused by reduced apical dominance related to shoot tip injuries.
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    Economics and Biological Evolution (1997)
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    Environmental and resource economics 9 (1997), S. 429-449 
    Details
    ISSN: 1573-1502
    Keywords: evolution ; economics ; pesticide resistance ; antibiotic resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract The employment of insecticides raises the relative fitness of resistant insects; the use of antibiotics applies selection pressure in favour of resistant strains of bacteria; lower limits on fish net mesh size raises the advantages of smaller adults. These are some of the many examples of the unintended impact of human activity upon biological evolution. Often this evolution has economic significance, as it does in the examples quoted. This paper examines some of the principles involved and provides a preliminary analysis of the extent to which the economically optimal inducement of evolution differs from that arising when changes in selection pressures are not anticipated.
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    URL: http://dx.doi.org/10.1023/A:1026411423178
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    Cuticular Hydrocarbons as Chemotaxonomic Characters of Pine Engraver Beetles (Ips spp.) in the grandicollis Subgeneric Group (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 1053-1099 
    Details
    ISSN: 1573-1561
    Keywords: Scolytidae ; Ips ; Orthotomicus ; Pinus ; evolution ; cuticular hydrocarbons ; chemotaxonomy ; methyl-branched hydrocarbons ; mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Cuticular hydrocarbons were extracted, identified, and evaluated as chemotaxonomic characters from all species of adult Ips pine engraver beetles in the grandicollis subgeneric group. The grandicollis group consists of Ips grandicollis (Eichhoff), I. cribricollis (Eichhoff), I. lecontei Swaine, I. montanus (Eichhoff), I. paraconfusus Lanier, I. confusus (LeConte), and I. hoppingi Lanier. In order to provide outgroups for a phylogenetic analysis, cuticular hydrocarbons were also analyzed from Orthotomicus caelatus (Eichhoff), I. latidens (LeConte) (latidens subgeneric group), and I. pini (Say) (pini subgeneric group). Two hundred forty-eight hydrocarbon components were identified by gas chromatography–mass spectrometry. The members of the grandicollis group provided 206 of these compounds. The components represented eight classes: n-alkanes, alkenes, alkadienes, terminally branched methylalkanes, internally branched methylalkanes, dimethylalkanes, trimethylalkanes, and tetramethylalkanes. Different populations of O. caelatus, I. grandicollis, I. lecontei, I. montanus, I. paraconfusus, I. confusus, and I. hoppingi provided no evidence for interpopulational variation in cuticular hydrocarbons. Single populations only were analyzed for I. latidens, I. pini, and I. cribricollis. Sexual dimorphism in cuticular hydrocarbons occurred only in I. lecontei where females produced eight unique components with a pentatriacontane parent chain. Several phylogenetic analyses based on hydrocarbon phenotypes agreed in general with the established morphologically based system of relatedness and with published phylogenies reconstructed from protein and nucleic acid characters. Nearly all hydrocarbon analyses suggested a close relationship between I. grandicollis and I. cribricollis; between I. lecontei and I. montanus; and among the sibling species I. paraconfusus, I. confusus, and I. hoppingi. The presence or absence of specific n-alkanes (n-docosane, n-triacontane); certain dimethylalkanes (terminally branched with octacosane and triacontane parent chains and internally branched with heptacosane, hentriacontane, and docotriacontane parent chains); and 3,7,11-; 3,7,15-trimethylheptacosane permit facile discrimination of I. paraconfusus, I. confusus, and I. hoppingi. These three sibling species are difficult to resolve by external morphology. These data support the species status of I. hoppingi rather than it being considered a host race of the I. confusus complex. They also support the species status of I. cribricollis rather than it being considered part of I. grandicollis. In contrast to other published phylogenies reconstructed from molecular data, phylogenies reconstructed from cuticular hydrocarbons repeatedly place I. lecontei as an integral part of the grandicollis subgeneric group. Thus, cuticular hydrocarbon and pheromone alcohol composition of I. lecontei support its inclusion in the grandicollis subgeneric group.
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    Temperature effect on shear induced transition in surfactant solution (1997)
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    Colloid & polymer science 105 (1997), S. 322-325 
    Details
    ISSN: 1435-1536
    Keywords: Rheology ; surfactant solutions ; micelles ; phase transition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Aqueous solutions of cationic surfactant with binding counterions exhibit a transition under shear. In this paper the steady shear properties of semidilute aqueous micellar solutions (cetylpyridinium chloride and sodium salicylate in brine) are presented as a function of concentration and temperature. The shear thinning behavior of this system could be described by the Carreau model at low shear rate and by a power law at higher shear rate. The temperature dependence of the zero shear viscosity follows an Arrhenius relationship. The critical shear rate at which the viscosity departs from its zero shear value is found to increase with temperature indicating the influence of this parameter on transition.
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    The effect of various host species on the feeding performance of immature stages of the tick Hyalomma truncatum (Acari: Ixodidae) (1997)
    Springer
    Experimental and applied acarology 21 (1997), S. 551-559 
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    ISSN: 1572-9702
    Keywords: Ticks ; Hyalomma truncatum ; feeding performance ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to determine the effect of various hosts on the feeding performance of the tick Hyalomma truncatum, we used three mammalian species as hosts. Larvae and nymphs of H. truncatum were fed, under controlled laboratory conditions, on gerbils, guinea-pigs and rabbits. The larvae fed for 4.3±1.4 days on gerbils, 5.6±1.3 days on guinea-pigs and 4.7±1.2 days on rabbits. The mean weights of the larvae which fed on the rabbits, guinea-pigs and gerbils were 0.58± 0.09, 0.46±0.04 and 0.45±0.04 mg. respectively. The feeding periods of the nymphs on gerbils, guinea-pigs and rabbits were 7.9±1.3, 8.6±1.3 and 9.6±2.2 days respectively. The mean weights of the nymphs which fed on the gerbils, guinea-pigs and rabbits were 22.5±2.8, 19.7±1.3 and 15.8±1.4 mg, respectively. Hyalomma truncatum demonstrated a life cycle of a three-host tick on gerbils and guinea-pigs and of a two-host tick on rabbits. The evolutionary advantage of a two-host cycle over a three-host cycle in metastriate ticks is discussed.
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    Diel activity of Ixodes ricinus Acari: Ixodidae at two locations near Stockholm, Sweden (1997)
    Springer
    Experimental and applied acarology 21 (1997), S. 247-256 
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    ISSN: 1572-9702
    Keywords: Diel abundance ; activity ; temperature ; Ixodes ricinus ; ticks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diel ‘activity’, i.e. availability, of Ixodes ricinus larvae, nymphs and adults was investigated in a meadow and a forest habitat near Stockholm during 1991–1993. Generally, the immature ticks were more prevalent in the forest than in the meadow. In the meadow, the mean larval and adult numbers varied significantly between 4 h time intervals with the peak activity from 2300 to 0300 h. In the forest, the tick numbers did not differ significantly between the time intervals. The association of the tick activity with certain meteorological variables was strongest in the meadow, where the mean numbers of all tick stages were negatively correlated with the temperature. The relative humidity was positively correlated only with the mean numbers of larvae. In contrast, the larval activity in the forest was positively and negatively correlated with the temperature and relative humidity, respectively, while the nymphal and adult activity showed no association with these climatic variables. The impact of the host activity on the tick diel activity is also discussed.
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    Bacterial evolution and silicon (1997)
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    Antonie van Leeuwenhoek 71 (1997), S. 271-276 
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    ISSN: 1572-9699
    Keywords: bacteria ; evolution ; molecular ; silicon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review examines the possible role of silicon in molecular evolution. It is possible silicon participated in early molecular evolution by providing a stable mineral surface or gel structure where the assembly and replication of primitive genetic information occurred. However, as molecular evolution proceeded, silicon was not required in the evolution of C-based organisms. Silicon can be accumulated by diatoms and other living organisms such as silicoflagellates, some xanthophytes, radiolarians and actinopods and plants such as grasses, ferns, horseradish, some trees and flowers, some sponges, insects and invertebrates and bacteria and fungi. Silicon also has a role in synthesis of DNA, DNA polymerase and thymidylate kinase activity in diatoms. It is not unreasonable to examine the role of silicon in early molecular evolution as it may have been part of a micro-environment in which assembly of genetic information occurred.
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    Chloroplast DNA diversity in brinjal eggplant (Solanum melongena L.) and related species (1997)
    Springer
    Euphytica 97 (1997), S. 295-301 
    Details
    ISSN: 1573-5060
    Keywords: chloroplast DNA ; brinjal eggplant ; Solanum incanum ; Solanum melongena ; Solanum aethiopicum ; systematics ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Chloroplast DNA (cpDNA) samples of brinjal eggplant (S. melongena) and representative related species including S. incanum sensu lato (or S. campylacanthum sensu stricto), S. lichtensteinii, S. marginatum, S. macrocarpon, S. anguivi and S. aethiopicum and also S. nigrum as an outgroup taxon, were digested by 14 restriction enzymes and analyzed by using electrophoresis and a cpDNA probe. All the species used here were clearly separated in the cpDNA analysis, except the pair S. anguivi and S. aethiopicum. From the dendrogram constructed by the unweighted pair-group method, it is suggested that S. incanum is the closest to S. melongena and the next closest species is S. macrocarpon followed by S. aethiopicum (and S. anguivi), S. lichtensteinii, S. marginatum and finally the outgroup taxon S. nigrum. The tree derived by the neighbour-joining method suggests phyletic relationships that agree with those indicated by crossability and seed coat anatomy, but conflict with conventional classifications based on morphology. In particular, members of sections Oliganthes and Melongena are not separated and no cpDNA variation was found within either of the morphologically diverse cultigens, S. aethiopicum and S. melongena. Paradoxically, the morphologically similar species S. incanum, S. lichtensteinii and S. marginatum have diverged greatly in their cpDNA. The significance of these results is discussed.
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    The impact of molecular systematics on hypotheses for the evolution of root nodule symbioses and implications for expanding symbioses to new host plant genera (1997)
    Springer
    Plant and soil 194 (1997), S. 185-192 
    Details
    ISSN: 1573-5036
    Keywords: actinorhizal plants ; evolution ; nitrogen fixation ; phylogenetic hypotheses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Current taxonomic schemes place plants that can participate in root nodule symbioses among disparate groups of angiosperms. According to the classification scheme of Cronquist (1981) which is based primarily on the analysis of morphological characters, host plants of rhizobial symbionts are placed in subclasses Rosidae and Hamamelidae, and those of Frankia are distributed among subclasses Rosidae, Hamamelidae, Magnoliidae and Dilleniidae. This broad phylogenetic distribution of nodulated plants has engendered the notion that nitrogen fixing endosymbionts, particularly those of actinorhizal plants, can interact with a very broad range of unrelated host plant genotypes. New angiosperm phylogenies based on DNA sequence comparisons reveal a markedly different relationship among nodulated plants and indicate that they form a more coherent group than has previously been thought (Chase et al., 1993; Swensen et al., 1994; Soltis et al., 1995). Molecular data support a single origin of the predisposition for root nodule symbiosis (Soltis et al., 1995) and at the same time support the occurrence of multiple origins of symbiosis within this group (Doyle, 1994; Swensen, 1996; Swensen and Mullin, In Press).
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    Biological nitrogen fixation in non-leguminous field crops: Facilitating the evolution of an effective association between Azospirillum and wheat (1997)
    Springer
    Plant and soil 194 (1997), S. 65-79 
    Details
    ISSN: 1573-5036
    Keywords: Azospirillum brasilense ; evolution ; nifA-lacZ ; nifH-lacZ ; nitrogen fixation ; para-nodules ; symbiosis ; wheat ; 2 ; 4-D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Recent advances towards achieving significant nitrogen fixation by diazotrophs in symbioses with cereals are reviewed, referring to the literature on the evolution of effective symbioses involving rhizobia and Frankia as microsymbionts. Data indicating that strains of Acetobacter and Herbaspirillum colonizing specific cultivars of sugarcane as endophytes make a significant contribution to the nitrogen economy of this crop improves the prospects that similar associative systems may be developed for other gramineous species such as rice and wheat. By contrast, the transfer of nodulation genes similar to those in legumes or Parasponia to achieve nodulation in crops like rice and wheat is considered to be a more ambitious and distant goal. Progress in developing an effective associative system for cereals has been materially assisted by the development of genetic tools based on the application of lacZ and gusA fusions with the promoters of genes associated with nitrogen fixation. These reporter genes have provided clear evidence that ‘crack-entry’ at the points of emergence of lateral roots or of 2,4-D induced para-nodules is the most significant route of endophytic colonization. Furthermore, using the laboratory model of para-nodulated wheat, there is now evidence that the ability of azospirilla and other nitrogen fixing bacteria to colonize extensively as endophytes can be genetically controlled. The most successful strain of Azospirillum brasilense (Sp7-S) for endophytic colonization and nitrogen fixation in wheat seedlings is a mutant with reduced exopolysaccharide production. Most other strains of azospirilla do not colonize as endophytes and it is concluded that though these are poorly adapted to providing nitrogen for the host plant, they are well adapted for survival and persistence in soil. A research program combining the study of endophytic colonization by azospirilla with an examination of the factors controlling the effectiveness of association (oxygen tolerance and nitrogen transfer) is now being pursued. It is proposed that a process of facilitated evolution of para-nodulated wheat involving the stepwise genetic improvement of both the prospective microsymbionts and the cereal host will eventually lead to effective nitrogen-fixing associations. In the attempt to achieve this goal, continued study of the endophytes occurring naturally in sugar cane and other grasses (e.g. Azoarcus sp.) should be of assistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004260222528
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  • 89
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    Effect of pre-incubation humidity and temperature treatment on the in vitro germination of avocado pollen grains (1997)
    Springer
    Euphytica 94 (1997), S. 247-251 
    Details
    ISSN: 1573-5060
    Keywords: Persea americana ; avocado humidity ; Greece ; pollen grain germination ; temperature ; fruit-set
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Optimum in vitro germination of pollen grain of the avocado cultivars Fuerte, Nabal, Ettinger, Bacon and Zutano occurred at 25 °C. However, there were significant differences between cultivars in percentage germination and relative humidity (RH) requirements for optimum pollen grain growth. The most sensitive cultivar to relative humidity was Fuerte, in which the germination of pollen grain rose from 11.4%, at 40% RH, to about 50%, after one hour at 100% RH. The germination% of Nabal pollen grain was already high at 40% RH and was not increased by higher relative humidity. Increased relative humidity also helped to sustain the viability of avocado pollen. At 30 °C and 5% RH the pollen grains of Fuerte quickly lost its ability to germinate, at 40% RH for 1 hour, germination was reduced spectacularly compared to pollen kept in saturated with moisture environment where it was not affected the first 24 hours. The effects of temperature and relative humidity on fruit-set and yield of avocado are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002917915386
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  • 90
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    Mutation in a novel gene required for photomixotrophic growth leads to enhanced photoautotrophic growth of Synechocystis sp. PCC 6803 (1997)
    Springer
    Photosynthesis research 53 (1997), S. 243-252 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; evolution ; glucose-sensitivity ; photoacclimation ; photosynthesis ; polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the glucose-tolerant strain of Synechocystis sp. PCC 6803, we found two types of cells with distinct growth properties. Under photoautotrophic conditions at any light intensity, one type gave larger colonies (designated WL) than the other (designated WS). Notably, the WL cells produced much larger colonies than the WS cells at higher light intensity. In contrast, growth of the WL cells was severely suppressed under mixotrophic conditions with glucose and light, while the WS cells grew normally. A gene which could complement the WL phenotype was obtained from a wild-type genomic library. The gene, designated pmgA, coded for a 23 kDa polypeptide of 204 amino acid residues with no apparent homology to known genes. In the WL genome, the base substitution of T for C at position 193 of pmgA caused replacement of Leu with Phe at position 65 of the product. The phenotype of pmgA disruption mutants was similar to that of the WL cells, indicating that the WS cells expressed a functional pmgA product. By direct sequencing of polymerase chain reaction-amplified pmgA from genomic DNA, it was revealed as an example of microevolution that WL had expelled WS from the photoautotrophic culture of wild-type in our laboratory for a year or so. Mixed culture in liquid also demonstrated that the WL cells increased gradually under photoautotrophic conditions, while they decreased rapidly under photomixotrophic conditions. These results suggest that pmgA product is essential for photomixotrophic growth, whereas it represses photoautotrophic growth. To our knowledge, the WL cells and pmgA-disrupted mutants are the first in cyanobacteria, which shows much improved photosynthetic growth than wild-type especially at high light intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005879905365
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  • 91
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    The role of marine biota in the evolution of terrestrial biota: Gases and genes (1997)
    Springer
    Biogeochemistry 39 (1997), S. 139-164 
    Details
    ISSN: 1573-515X
    Keywords: atmospheric composition ; elemental composition ; evolution ; marine biota ; soils ; terrestrial biota
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract There is greater biodiversity (in the senseof genetic distance among higher taxa) ofextant marine than of terrestrialO2-evolvers. In addition tocontributing the genes from one group ofalgae (Class Charophyceae, DivisionChlorophyta) to produce by evolution thedominant terrestrial plants (Embryophyta),the early marine O2-evolvers greatlymodified the atmosphere and hence the landsurface when the early terrestrialO2-evolvers grew. The earliestterrestrial phototrophs (from geochemicalevidence) occurred 1.2 Ga ago, over 0.7 Gabefore the Embryophyta evolved, but wellafter the earliest marine (cyanobacterial)O2 evolvers (3.45 Ga) and marineeukaryotic O2 evolvers (2.1 Ga). Evenby the time of evolution of the earliestterrestrial O2-evolvers the marineO2-evolvers had modified the atmosphereand land environment in at least thefollowing five ways. Once photosyntheticO2 paralleling organic C burial hadsatisfied marine (Fe2+, S2-reductants, atmospheric O2 built (1) upto a considerable fraction of the extantvalue (although some was consumed inoxidising terrestrial exposed Fe2+ and(2) provided stratospheric O3 and thusa UV-screen. (3) CO2 drawdown to∼20-30times the extant level is attributableto net production, and burial, of organic Cin the oceans (plus other geologicalprocesses). Furthermore, (4) theirproduction of volatile organic S compoundscould have helped to supply S to inland sitesbut also (5) delivered Cl and Br to thestratosphere thus lowering the O3 leveland the extent of UV screening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005855528289
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  • 92
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    The biology of salmon growth hormone: from daylight to dominance (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 9-24 
    Details
    ISSN: 1573-5168
    Keywords: growth hormone ; insulin-like growth factor I ; salmonids ; secretion ; regulation ; metabolism ; photoperiod ; temperature ; smoltification ; seawater tolerance ; appetite ; aggression ; predator avoidance ; behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The elucidation of the molecular structure of salmon growth hormone (GH) in the mid-1980's paved the way for a new era of endocrinological research. Establishment of homologous immuno- and receptor-assays have made studies of the secretion, tissue and plasma GH levels, GH turn-over and GH receptor concentrations possible. This overview attempts to summarize the present understanding of the biological roles of GH in salmon. Although the involvement of GH in the regulation of physiological processes throughout the salmon life history has yet to be comprehensively explored, the hormone has already been demonstrated to have several important functions. GH is a principal regulator of somatic growth in salmonids. The growth-stimulating effect of GH is probably integrated with that of insulin-like growth factor I (IGF-I), as in later vertebrates. GH stimulates protein synthesis and improves feed conversion during growth. The hormone also promotes lipid and glycogen breakdown as well as gluconeogenesis, functions which are probably of great importance during starvation when GH levels are seen to increase. During parr-smolt transformation of anadromous salmonids, circulating GH levels appear to be governed by environmental cues. Increasing springtime daylength elevates GH levels, and temperature modulates the photoperiod regulation of GH. The seawater-adapting role of GH during the parr-smolt transformation is complex. In freshwater, GH improves hypoosmoregulatory ability by stimulating branchial Na+,K+-ATPase activity and probably also acts in kidney and intestine. Following seawater entry, GH levels and turn-over increase transiently, probably to further increase seawater tolerance. Accumulating in vitro and in vivo data support the conclusion that GH is involved in the regulation of sexual maturation in salmonids although further studies are needed to establish the exact role of GH in this process. GH increases appetite but it is unclear whether the hormone effects the central nervous system directly, or acts indirectly through metabolic changes. GH increases swimming activity as well as dominant feeding behaviour and diminishes anti-predator behaviour of juvenile salmonids. The GH-induced changes of behavioural patterns imply that there exists an ecological trade-off between high growth rate and long-term survival which may explain why natural fish populations normally grow at sub-maximal rates. Current knowledge indicates that GH is an important and multi-functional hormone in salmon and a central mediator of seasonal changes in physiology and behaviour. The regulatory effects of GH are also of great applied interest as they are likely to affect both product quality in aquaculture and long-term survival of released fish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007712413908
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  • 93
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    The Wap65 gene expression of goldfish (Carassius auratus) in association with warm water temperature as well as bacterial lipopolysaccharide (LPS) (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 423-432 
    Details
    ISSN: 1573-5168
    Keywords: temperature ; acclimation ; cytokine ; enhancer ; goldfish ; hemopexin ; hepatopancreas ; immune system ; plasma protein ; lipopolysaccharide ; transcription ; Wap65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the Wap65 mRNA was compared between hepatopancreas, intestine, ovary, heart, gill, eye, skin, hemocytes, muscle, and brain from 30 °C-acclimated goldfish (Carassius auratus) by reverse transcription PCR, demonstrating the highest levels of expression of the gene in the hepatopancreas. Other tissues expressing the gene were ovary, gill, eye, and muscle, whereas Wap65 mRNA could not be detected in intestine, heart, skin, and brain. In Northern blot analysis, levels of Wap65 mRNA in the hepatopancreas increased after raising water temperature from 10 to 30 °C. The transcript levels reached a maximum of 40-fold on day 3 following temperature shift. On day 21 after raising water temperature, levels were 10-fold compared with those of the 10 °C-acclimated fish. Subsequently, in order to elucidate the transcriptional mechanisms of Wap65, a part of the Wap65 gene was cloned from a genomic library. The 5′-flanking region and introns of this gene contained enhancer motifs including cytokine responsive elements previously identified in mammals. The suggesting that some of these motifs are involved in the transcriptional regulation of Wap65, was tested by administering of lipopolysaccharide (LPS) to the 10 °C-acclimated goldfish. This resulted in the accumulation of Wap65 mRNA in the hepatopancreas, suggesting the involvement of immune associated factors in the regulation of transcription of Wap65.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007768531655
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    Independent amplification of two classes of Tourists in some Oryza species (1997)
    Springer
    Genetica 101 (1997), S. 145-152 
    Details
    ISSN: 1573-6857
    Keywords: evolution ; Oryza ; Tourist ; transposable element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transposable elements similar to Tourist elements from maize were isolated from the rice genome. The elements were about 300 bp, exhibited short terminal inverted repeats (TIR), and appeared to show preferential insertion at TAA sites. Some rice Tourist elements seem to have recently transposed. Based on the sequences of cloned elements, two classes of rice Tourist elements have been identified. Members of these two classes apparently amplified independently at different times in the past.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018328423736
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  • 95
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    Photoperiodic manipulations of the reproductive cycle of sea bass (Dicentrarchus labrax) and their effects on gonadal development, and plasma 17ß-estradiol and vitellogenin levels (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 211-222 
    Details
    ISSN: 1573-5168
    Keywords: teleost ; sea bass ; Dicentrarchus labrax ; photoperiod ; temperature ; reproduction ; spawning ; gametogenesis ; estradiol ; vitellogenin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The annual profile of plasma vitellogenin (VTG) and 17ß-estradiol (E2) levels, as well as gonadal development and spawning characteristics were investigated in captive female sea bass (Dicentrarchus labrax). Endocrine and gonadal changes were studied in fish reared under natural conditions or exposed to manipulated photothermal cycles. In natural conditions of photoperiod and temperature, sea bass spawned from February through March (East coast of Spain, 40°N 0°E). One or two months of constant long-days (15L/9D) in a constant short-day photoperiod regime (9L/15D) all-year-round, given early in the year (March and March–April), advanced spawning by 3 months. The same treatment applied later in the year (September–October) delayed spawning by 1 month, compared to controls. In all groups, changes in plasma VTG levels were correlated with E2 levels, oocyte growth and spawning time. In control females, VTG was low (〈100 ng ml-1) during the summer, until its first surge in plasma 4 months before the beginning of spawning. The VTG (3.1 ± 0.3 mg ml-1) and E2 (4.1 ± 0.5 ng ml-1) levels showed a single annual peak during late vitellogenesis, the time of the highest proportion of vitellogenic oocytes in the ovary. Constant high levels of VTG (1–1.4 mg ml-1) and E2 (1.6–1.9ng ml-1) were maintained during the entire spawning time, together with the presence of vitellogenic oocytes, suggesting the existence of several waves of oocyte growth in the ovary and thus, several spawns per female. Endocrine profiles and oocyte development in fish exposed to constant photoperiods were similar to controls, but were shifted in time in relation to the displacement of the spawning time. In the fish showing advanced spawns, the duration of the gametogenic proces was compressed when compared to controls. The differences observed in the evolution of the reproductive-related factors in the advanced groups, which were exposed to a reduction in temperature to 15°C, suggest an influence of the temperature in the early stages of the reproductive cycle in sea bass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007777816306
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  • 96
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    The chromosomal distributions of Ty1-copia group retrotransposable elements in higher plants and their implications for genome evolution (1997)
    Springer
    Genetica 100 (1997), S. 197-204 
    Details
    ISSN: 1573-6857
    Keywords: in situ ; hybridization ; centromeres ; retrotransposons ; genome organization ; evolution ; sequence evolution ; Arabidopsis ; barley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Retrotransposons make up a major fraction – sometimes more than 40% – of all plant genomes investigated so far. We have isolated the reverse transcriptase domains of the Ty1-copia group elements from several species, ranging in genome size from some 100 Mbp to 23 000 Mbp, and determined the distribution patterns of these retrotransposons on metaphase chromosomes and within interphase nuclei by DNA:DNA in situ hybridization. With some exceptions, the reverse transcriptase domains were distributed over the length of the chromosomes. Exclusion from rDNA sites and some centromeres (e.g., slash pine, 23 000 Mbp, or barley, 5500 Mbp) is frequent, whereas many species exclude retrotransposons from other sites of heterochromatin (e.g., intercalary and centromeric sites in broad bean). In contrast, in the plant Arabidopsis thaliana, widely used for plant molecular genetic studies because of its small genome (c. 100 Mbp), the Ty1-copia group reverse transcriptase gene domains are concentrated in the centromeric regions, collocalizing with the 180 bp satellite sequence pAL1. Unlike the pAL1 sequence, however, the Ty1-copia signal is also detectable as weaker, diffuse hybridization along the lengths of the chromosomes. Possible mechanisms for evolution of the contrasting distributions are discussed. Understanding the physical distribution of retrotransposons and comparisons of the distribution between species is critical to understanding their evolution and the significance for generation of the new patterns of variability and in speciation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018337831039
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  • 97
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    Cytogenetics of the Genus Leporinus (Pisces, Anostomidae). II. Molecular Cytogenetics, Organization and Evolutionary Conservation of a Chromosome-Specific Satellite DNA from Leporinus obtusidens (1997)
    Springer
    Chromosome research 5 (1997), S. 325-331 
    Details
    ISSN: 1573-6849
    Keywords: evolution ; fish molecular cytogenetics ; Leporinus ; satellite DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chromosome-specific satellite DNA from the South American fish species Leporinus obtusidens has been isolated and characterized. Sequence analysis and Southern hybridization studies indicate that the cloned 483-bp fragment is 60% AT rich and appears to comprise two diverged monomers. A highly variable low-copy number polymorphism was detected and, thus, this satellite DNA may serve as a valuable genetic marker. Using a Southern blot approach, the cloned satellite DNA cross-hybridized strongly to the DNA of Leporinus elongatus but failed to detect homologous sequences in the genomes of other closely related Leporinus species and higher vertebrates. Using fluorescence in situ hybridization to mitotic metaphase spreads of L. obtusidens and L. elongatus, this satellite DNA was located to the (peri)centromeric region of one single chromosome pair in both species. As the cloned satellite DNA sequence clearly evolved along a chromosomal lineage and is highly variable, it may serve as a very useful marker in further genetic, molecular and cytogenetic studies of the genus Leporinus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:CHRO.0000038763.52875.48
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  • 98
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    Do the integrases of LTR-retrotransposons and class II element transposases have a common ancestor? (1997)
    Springer
    Genetica 100 (1997), S. 63-72 
    Details
    ISSN: 1573-6857
    Keywords: DDE signature ; evolution ; integrase ; transposable elements ; transposase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The integrases of retrotransposons (class I) and retroviruses and the transposases of bacterial type elements (class II) were compared. The DDE signature that is crucial for the integration of these elements is present in most of them, except for the non-LTR retrotransposons and members of the hAT and P super-families. Alignment of this region was used to infer the relationships between class II elements, retrotransposons, and retroviruses. The mariner-Tc1 and the Pogo-Fot1 super-families were found to be closely related and probably monophyletic, as were LTR retrotransposons and retroviruses. The IS elements of bacteria were clustered in several families, some of them being closely related to the transposase of the mariner-Tc1 super-family or to the LTR retrotransposon and retrovirus integrases. These results plus that of Xiong and Eickbush (1990) were used to develop an evolutionary history suggesting a common ancestral origin(s) for the integrases and transposases containing the DDE signature. The position of the telomeric elements (Het-A and TART) was assessed by comparing their gag and reverse transcriptase domains (when present) to those of group II introns and non-LTR retrotransposons. This preliminary analysis suggests that telomeric elements may be derived from non-LTR retrotransposons.
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    URL: http://dx.doi.org/10.1023/A:1018300721953
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  • 99
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    Genomic distribution of the retrovirus-like element ZAM in Drosophila (1997)
    Springer
    Genetica 100 (1997), S. 131-140 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; evolution ; FISH on Drosophila chromosomes ; genomic distribution ; retrotransposons retrovirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mobile element ZAM, recently identified in Drosophila melanogaster, is similar in structure and coding potential to vertebrate retroviruses. In this paper, we analyze the insertional and structural polymorphism of this element and show that members of this family appear to have a long evolutionary history in the genome of Drosophila. It is present in all the species of the D. melanogaster subgroup and in more distantly related species like D. takahashii, D. ananassae, or D. virilis but in a lower copy number or with a lower homology. Two categories of strains have been previously identified in D. melanogaster: strains with a high copy number of ZAM and strains with a low copy number. Here, we show that ZAM is at least in a low copy number in each tested strain of the species analyzed. The study of ZAM's genomic distribution by FISH mapping analysis to salivary gland polytene chromosomes or on mitotic chromosomes indicates that most of the insertion sites of ZAM elements are associated with the constitutive heterochromatin regardless of the ZAM copy number. In addition, our results suggest that multiple ZAM elements are present at the insertion sites visualized by in situ experiments.
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    URL: http://dx.doi.org/10.1023/A:1018317209658
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  • 100
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    Effect of Ionic Composition and Temperature on the Radiocaesium Fixation in Freshwater Sediments (1997)
    Springer
    Water, air & soil pollution 99 (1997), S. 201-208 
    Details
    ISSN: 1573-2932
    Keywords: freshwater sediments ; radiocaesium ; fixation ; ionic composition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The objective of this study was to verify in which way the ionic composition of the sediment and that of the overlying water column may have an effect on radiocaesium fixation, through possible structural modifications of the frayed edge sites (FES) pools of the sediments. Two experimental protocols have been considered: i) a condition in which sediments were homoionically saturated with either potassium, ammonium, calcium, magnesium or sodium ions, and ii) a mixed potassium-calcium scenario in the liquid phase. Nine freshwater sediments from four different locations were used in this study. For homoionic potassium and ammonium saturated sediments a nearly quantitative radiocaesium desorption (90-100%) was observed, whereas for calcium and magnesium the desorption yields were about 20%. It appears that the action of strongly hydrated ions (Na+, Mg2+, Ca2+) leads to a pronounced enhancement of radiocaesium fixation in the solid phase, whereas poorly hydrated ions (K+, NH4 +) have the opposite effect and promote sorption reversibility. Another issue considered in this study concerns the effect of temperature and sediment drying on the radiocaesium fixation. Drying the sediments at 110°C leads to a significant increase in radiocaesium fixation levels, while drying the sediments at room temperature (25°C) has a very limited effect on radiocaesium fixation and appears to put a brake on the aging effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018361121952
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