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  • RFLP  (237)
  • temperature
  • Springer  (447)
  • American Institute of Physics (AIP)
  • 2010-2014
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  • 1990-1994  (352)
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  • 1
    ISSN: 1570-7458
    Keywords: Anagyrus kamali ; Encyrtidae ; parasitoid ; Maconellicoccus hirsutus ; Pseudococcidae ; host density ; functional response ; temperature ; photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The peformance of the parasitoid Anagyrus kamali Moursi [Hymenoptera: Encyrtidae], as a function of host density, temperature, and photoperiod was investigated with the objective to optimize a mass-rearing system in the context of a biological control program. The number of hosts parasitized at densities varying from 2–100 hibiscus mealybug (HMB), Maconellicoccus hirsutus Green [Homoptera: Pseudococcidae], corresponded to a type II-III functional response in fixed-time conditions and a type III in variable-time conditions. Twenty-six percent of the oviposited eggs led to progeny emergence with a sex ratio of 0.49±0.102 (M/F), regardless of host density. Fecundity and oviposition period under six abiotic combinations (i.e., two temperatures (26±2 °C and 32±2 °C) and three photoperiods (L0:D24, L12:D12, L24:D0)) were measured. Lifetime fecundity and reproductive life were significantly affected by temperature and photoperiod conditions. Optimum female parasitoid lifetime fecundity was attained at 26±2 °C, L0:D24 with an average of 116.1±17.43 eggs. At 32±2 °C, L24:D0 and L12:D12, an average of 79.4±34.57 and 85.8±35.81 eggs were laid, respectively. Reproductive longevity was maximal at 26±2 °C, L0:D24 with 12±4.85 days of oviposition. Because the parasite A. kamali can be reared optimally without light, this may save tremendous energy costs.
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  • 2
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    Electronic Resource
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    Entomologia experimentalis et applicata 95 (2000), S. 173-184 
    ISSN: 1570-7458
    Keywords: Aphidius ervi ; Aphidius rhopalosiphi ; Praon volucre ; Sitobion avenae ; temperature ; development time ; parasitization ; superparasitization ; lower temperature thresholds ; immature mortality ; sex ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Temperature dependencies were established for the egg-to-mummy and mummy-to-adult phases, for mummy mortality, and for parasitism of Aphidius ervi Haliday, Aphidius rhopalosiphi De Stefani-Perez, and Praon volucre (Haliday) (Hymenoptera, Aphidiidae), three parasitoids of Sitobion avenae (Fabricius) (Homoptera, Aphididae), at 8 °C, 12 °C, 16 °C, 20 °C, and 25 °C on winter wheat (cv. Haven). A physiological model described temperature-dependent development over the full temperature range, whereas a linear model was fitted for data above 8 °C and used to estimate the lower temperature thresholds and day-degrees (° D) required for development. The thresholds for A. ervi were 2.2 °C for egg-mummy development and 6.6 °C for mummy-adult development, those for A. rhopalosiphi were 4.5 °C and 7.2 °C, and those for P. volucre were 3.8 °C and 5.5 °C. The time to develop into mummies and adults differed significantly between the three species: A. ervi development into mummies required an average of 159 ° D, while development into adults took an average of 73 ° D. The corresponding average times required for A. rhopalosiphi and P. volucre to develop mummies were 124° D and 126° D, while their development into adults required an average of 70° D and 150° D, respectively. Mummy mortality was 25–35% at 8 °C and less at the higher temperatures tested, but began to increase again at 25 °C, showing a quadratic relationship between mortality and temperature. Parasitization was very low or, in the case of P. volucre, absent up to 12 °C and thereafter increased with increasing temperature. The relationship between parasitization, recorded as percent aphids mummified, and temperature was linear at the temperatures tested and depended on species. A. ervisuperparasitized 11.1% aphids at 20 °C and 16.6% aphids at 25 °C, whereas superparasitism was low in A. rhopalosiphi and absent in P. volucre. From 16 °C to 25 °C the P. volucre sex ratio increased. For A. ervi and A. rhopalosiphi there was no trend with temperature, but at 20 °C and 25 °C it was close to even. Field data for 1996 and 1997 allowed for a comparison of actual and expected emergence of overwintering mummies. In both years, parasitoids were predicted to have emerged from overwintering mummies well in advance of the onset of aphid infestation, and more than a month earlier than the first parasitized aphids were found in winter wheat. Observations from trap plants in other crops supported the predictions of the models. Other factors that can affect biological control by cereal aphid parasitoids are discussed.
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  • 3
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    Journal of solution chemistry 29 (2000), S. 63-86 
    ISSN: 1572-8927
    Keywords: Thorium ; hydrolysis ; potentiometry ; solvent extraction ; temperature ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stability constants of thorium(IV) hydrolysis species have been measured at15, 25, and 35°C (in 1.0 mol dm−3 NaClO4) using both potentiometry and solventextraction. The results indicate the presence of the monomeric speciesTh(OH)3+, Th(OH)2+ 2, Th(OH)+ 3, and Th(OH)4, in addition to the polymericspecies Th4(OH)8+ 8 and Th6(OH)9+ 15. The polymeric species were found to beimportant, although the total thorium concentration was limited to 0.01–0.1mmol-dm−3. The solvent extraction measurements required the use of acetylacetone.As such, the stability constants of thorium(IV) with acetylacetone were alsomeasured using both potentiometry and solvent extraction. All logarithms of thestability constants were found to be linear functions of the reciprocal absolutetemperature indicating that ΔH o and ΔSo of reaction are both independent oftemperature (over the temperature range examined in the study).
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  • 4
    ISSN: 1572-8927
    Keywords: Flow-through cell ; conductivity ; electrolyte ; ion association ; temperature ; pressure ; LiCl ; NaCl ; KCl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A flow-through electrical conductance cell was assembled in order to measuremolar conductances of dilute aqueous electrolytes with a high degree of accuracyat high temperatures and pressures. The design of the cell is based on the conceptdeveloped at the University of Delaware and built in 1995, with modificationsthat will allow the cell to operate at much higher temperatures (to 600°C) andpressures (to 300 MPa). At present, the cell has been tested successfully bymeasuring aqueous (10−4-10−3 mol-kg−1) solutions of LiCl, NaCl, and KCl attemperatures 25–410°C and pressures 9.8–33 MPa. The results are in goodagreement with reported values, including those measured with the Delawareflow-through cell. These new results are also complementary to our previousresults, which were measured with a static high-pressure cell. Measurements attemperatures near the critical point of water (374°C, 22.1 MPa) require the useof lower solution concentrations that were unachievable in the past with thestatic cell.
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  • 5
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    Theoretical and applied genetics 100 (2000), S. 564-568 
    ISSN: 1432-2242
    Keywords: Key words Triticum aestivum ; Tritiam timopheevii ; Pm6 ; Introgression lines ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Pm6 in bread wheat (Triticum aestivum L.), which was transferred from Triticum. timopheevii L., is a gene conferring resistance to the powdery mildew disease caused by Erysiphe graminis f. sp. tritici. Six near-isogenic lines ( NILs ) of Pm6 in a cultivar ’Prins’ background were analyzed to map this gene using restriction fragment length polymorphism (RFLP). Each of the six NILs possessed a T. timopheevii-derived segment, varying in length, and associated with powdery mildew resistance. Lines IGV1–465 (FAO163b/ 7*Prins) and IGV1–467 (Idaed 59B/7*Prins) had the shortest introgressed segments, which were detected only by DNA probes BCD135 and PSR934, respectively. The polymorphic loci detected by both probes were mapped to the long arm of chromosome 2B. Lines IGV1–458 (CI13250/7*Prins) and IGV1–456 (CI12559/8*Prins) contained the longest T. timopheevii segments involving both arms of donor chromosome 2G across the centromere. All these introgressed segments had an overlapping region flanked by the loci xpsr934 and xbcd135 on 2BL. Thus, Pm6 was located in this region since the powdery mildew resistance in all the NILs resulted from the introgressed fragments. Using the F2 mapping population from a cross of IGV1–463 (PI170914/7*Prins)×Prins, Pm6 was shown to be closely linked to the loci xbcd135 and xbcd266 at a genetic distance of 1.6 cM and 4.8 cM, respectively. BCD135 was successfully used in detecting the presence of Pm6 in different genetic backgrounds.
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  • 6
    ISSN: 1573-0417
    Keywords: diatoms ; climate change ; temperature ; pH ; transfer functions ; lake sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationships between diatoms (Bacillariophyceae) in surface sediments of lakes and summer air temperature, pH and total organic carbon concentration (TOC) were explored along a steep climatic gradient in northern Sweden to provide a tool to infer past climate conditions from sediment cores. The study sites are in an area with low human impact and range from boreal forest to alpine tundra. Canonical correspondence analysis (CCA) constrained to mean July air temperature and pH clearly showed that diatom community composition was different between lakes situated in conifer-, mountain birch- and alpine-vegetation zones. As a consequence, diatoms and multivariate ordination methods can be used to infer past changes in treeline position and dominant forest type. Quantitative inference models were developed to estimate mean July air temperature, pH and TOC from sedimentary diatom assemblages using weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regression. Relationships between diatoms and mean July air temperature were independent of lake-water pH, TOC, alkalinity and maximum depth. The results demonstrated that diatoms in lake sediments can provide useful and independent quantitative information for estimating past changes in mean July air temperature (R2 jack = 0.62, RMSEP = 0.86 °C; R2 and root mean squared error of prediction (RMSEP) based on jack-knifing), pH (R2 jack = 0.61, RMSEP = 0.30) and TOC (R2 jack = 0.49, RMSEP = 1.33 mg l-1). The paper focuses mainly on the relationship between diatom community composition and mean July air temperature, but the relationships to pH and TOC are also discussed.
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  • 7
    ISSN: 1349-9432
    Keywords: optical fibres ; temperature ; sensors ; tantalum pentoxide ; thermal optic ; thermal expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A fiber optic low-coherence sensor based on the spectral shift of tantalum pentoxide thin films for absolute temperature sensing up to 650°C is described. A tantalum pentoxide single layer was deposited directly onto the cleaved end-face of a single mode optical fibre and was illuminated with an super luminescence diode (SLD) source through a directional coupler. Interference fringes of the film on reflection were obtained within the optical bandwidth of the SLD using an optical spectrum analyser. The spectral shift versus temperature rise showed no turning points and the output was unambiguous, linear, monotonic and gave about 0.016 nm wavelength shift in the spectrum per°C. A semi-empirical calibration procedure based on the refractive index (n) and thickness (l) of the tantalum pentoxide film for absolute thermometric measurements is described.
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  • 8
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    Optical review 7 (2000), S. 555-560 
    ISSN: 1349-9432
    Keywords: lidar ; remote sensing ; Rayleigh scattering ; wind ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new method of simultaneous remote sensing of atmospheric wind and temperature by a ultraviolet Rayleigh lidar is described. This technique uses two narrowband filters located at either side of the wings of the Rayleigh backscatter spectrum to analyze Rayleigh backscattering signals. These filters are selected to be greatly sensitive to both velocity and temperature. By measuring the ratio and the sum of the two normalized filtered signals, the line-of-sight wind velocity and temperature profiles can be retrieved. A lidar system is proposed for the wind velocity and temperature measurements in the middle atmosphere, and the simulation results show that the accuracies of velocity and temperature are about 1 m/s and 2 K at the height of 30 km, respectively. The influence of aerosol component has been estimated for clear weather conditions, and with an uncertainty of aerosol component of 15% the errors are about 0.1 m/s and 2 K above the troposphere, respectively.
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  • 9
    ISSN: 1432-2242
    Keywords: Key words Chloroplast DNA ; Genetic diversity ; Ipomoeabatatas ; ISSR ; RFLP ; Sweetpotato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic diversity and relationships of 40 accessions of Ipomoea, representing ten species of series Batatas, were examined using ISSR markers and restriction-site variation in four non-coding regions of chloroplast DNA. A total of 2071 ISSR fragments were generated with 15 primers in these accessions and, on average, 52 bands per accession were amplified. Most of the primers contained dinucleotide repeats. The ISSR fragments were highly polymorphic (62.2%) among the 40 accessions studied. Restriction analysis of chloroplast (cp) DNA revealed 47 informative restriction-site and length mutations. Phylogenetic analyses of ISSR and cpDNA datasets generally revealed similar relationships at the interspecific level, but the high polymorphism of ISSRs resulted in a better separation of intraspecific accessions. However, the combined ISSR and cpDNA dataset appeared to be appropriate in resolving both intra- and interspecific relationships. Of the species examined, I. trifida was found to be the most closely related to cultivated sweetpotato, the hexaploid I. batatas, while I. ramosissima and I. umbraticola were the most distantly related to I. batatas within the series. Ipomoea triloba, hitherto considered to be one of the ancestors of sweetpotato, was only distantly related to sweetpotato based on ISSR similarity index.
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  • 10
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    Theoretical and applied genetics 100 (2000), S. 899-905 
    ISSN: 1432-2242
    Keywords: Key words Petunia ; RFLP ; Genetic map ; Genome ; Segregation distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Due in large part to the data accumulated from years of classic genetic analysis, petunia (Petunia hybrida Vilm) has remained a useful model system, particularly for studies of gene regulation and genome structure. We have used three segregating populations of petunia, including those serving as the source of an earlier actin gene RFLP map, for RFLP mapping of several additional genes. Twenty-seven loci have been merged with 11 previously mapped morphological and biochemical markers. Our results contribute additional evidence to reports of a high degree of genome plasticity and segregation distortion in this species and suggest that petunia may be a useful plant system for detailed analysis of plant genome organization, activity and evolution.
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  • 11
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    Theoretical and applied genetics 100 (2000), S. 1018-1024 
    ISSN: 1432-2242
    Keywords: Key words cpDNA ; Cytoplasmic male sterility ; mtDNA ; Olea europaea ; Inheritance ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The olive tree is usually hermaphrodite but self-incompatible. In the Western Mediterranean some cultivars are totally male-sterile. Three different male-sterile phenotypes have been recognised. To infer the genetic basis of male sterility we studied its inheritance and cytoplasmic diversity in wild (oleaster) and cultivated Mediterranean olive. In the cross Olivière×Arbequina, the male-sterile trait was maternally inherited and affected all progenies. We also checked that both chloroplast and mitochondrial DNAs are maternally inherited. RFLP studies on chloroplast and mitochondrial DNAs revealed several cytotypes: two chlorotypes and four mitotypes in cultivars and oleaster (wild or feral Mediterranean olive). Furthermore, a total linkage desequilibrium between the CCK chlorotype and the MCK mitotype in cultivars and oleaster from different regions supports the fact that paternal leakage of organelles was not observed. The male sterility (ms 2) displayed by Olivière, plus six other cultivars and three oleaster was strictly associated with the CCK chlorotype and the MCK mitotype. These facts suggest that Olivière carries cytoplasmic male sterility. Male-fertile and male-sterile oleasters carrying this cytotype showed the presence of restorer alleles. This CMS might be due to a distant cross between olive taxa. The two other male-sterile phenotypes displayed by Lucques (ms 1) and Tanche (ms 3) were associated with the ME1 mitotype but we have not demonstrated CMS.
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  • 12
    ISSN: 1432-2242
    Keywords: Key words Triticum aestivum ; Aegilops speltoides ; Chromosome addition ; C-banding ; In situ hybridization ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Aegilops speltoides Tausch (2n = 2x = 14, SS) is considered as the closest living relative of the B and G genomes of polyploid wheats. A complete set of Triticum aestivum L. cv Chinese Spring-Ae. speltoides whole chromosomes and seven telosomic addition lines was established. A low pairing accession was selected for the isolation of the chromosome addition lines. Except for chromosomes 3S and 6S, which are presently only available as monosomic additions, all other lines were recovered as disomic or ditelosomic additions. The individual Ae. speltoides chromosomes isolated in the wheat background were assayed for their genetic effects on plant phenotype and cytologically characterized in terms of chromosome length, arm ratio, distribution of marker C-bands, and FISH sites using a Ae. speltoides-specific repetitive element, Gc1R-1, as a probe. The homoeology of the added Ae. speltoides chromosomes was established by using a standard set of RFLP probes. No chromosomal rearrangements relative to wheat were detected.
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  • 13
    ISSN: 1432-2242
    Keywords: Keywords Alfalfa ; Post-meiotic cytokinesis ; RFLP ; 4n pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The objective of this research was to map the jumbo-pollen trait in diploid alfalfa. Homozygous recessive (jpjp) plants are characterized by the complete failure of post-meiotic cytokinesis during microsporogenesis resulting in 100% 4n-pollen formation. Three F1 segregating populations were produced and analyzed for pollen-grain production and the segregation of RFLP markers. The first cross combination did not segregate for the jumbo-pollen trait, but showed a clear segregation for multinucleate (bi-, tri- and tetra-nucleate)-microspore formation. Cytological analysis showed that few plants produced 100% normal (uninucleate) microspores, whereas most of them produced multinucleate microspores at a variable frequency (0–75%). Plants with multinucleate microspores always showed a prevalence of binucleated microspores, even though some plants showed a background presence of tri- and tetra-nucleate microspores. QTL analysis based on ANOVA I and Stepwise Multiple Regression identified three QTLs with a highly significant effect on multinucleate-microspore formation. Two cross combinations, subsequently executed, showed Mendelian segregation for the jumbo-pollen trait and were effective in locating the jp gene on linkage group 6 close to the Vg1G1b RFLP locus. Interestingly, this RFLP locus was also linked to one QTL for multinucleate-microspore formation. Genetic models are discussed concerning the presence in linkage group 6 of a cluster of genes involved in multinucleate-microspore formation together with possible relationships between the jp gene and the Vg1G1b QTL.
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  • 14
    ISSN: 1432-2242
    Keywords: Key words Acacia ; RFLP ; Restriction enzymes ; Genome mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Random genomic probes were used to assess levels of restriction fragment length polymorphism (RFLP) in two 2-generation outbred pedigrees of Acacia mangium Willd. Probes were evaluated for their ability to detect polymorphic loci in each pedigree and to determine the relative efficiency of different restriction enzymes in revealing polymorphisms. Sixty two percent of the probes which detected single- or low-copy number sequences revealed polymorphisms with at least one restriction enyzme. HpaII was the most efficient in detecting polymorphism among first-generation individuals. The recognition sequence of HpaII contains a CpG dimer, suggesting that cytosines in the CpG sequence may be hotspots for mutation in plant genomes, as previously reported in bacterial and mammalian genomes. Mendelian inheritance of 230 loci was demonstrated based on single-locus segregation in second-generation individuals. Less than 5% of loci showed evidence of segregation distortion. The proportion of fully informative loci (15%) was lower than previously reported in eucalypts reflecting the lower level of genetic diversity in A. mangium. The RFLP probes are suitable for the construction of a high-density genetic linkage map in A. mangium. Cross-hybridisation of the A.mangium RFLPs to DNA from species representing the three subgenera of the genus Acacia indicates that these markers could be used in breeding programs of other diploid acacias, for comparative studies of genome organisation, and for phylogenetic studies.
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  • 15
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    Theoretical and applied genetics 100 (2000), S. 602-606 
    ISSN: 1432-2242
    Keywords: Key words Triticum ; Hexaploid ; Mapping ; RFLP ; RSL ; Spelt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A dominant allele at the Q locus on chromosome 5A is believed to be the principal factor responsible for free-threshing, square-head spikes with a non-fragile rachis in bread wheat, Triticum aestivum ssp. aestivum. The spelt syndrome, resulting in pyramidal spikes with a brittle rachis and hulled grain in T. aestivum, is believed to be principally caused by the q allele. Chromosome 5A of European and Iranian spelt was substituted for 5A of bread wheat and the lines were characterized with molecular markers. The substitution of bread wheat chromosome 5A by 5A of European spelt resulted in weakly hulled, pyramidal spikes with a non-brittle rachis, whereas and the substitution of 5A by 5A of Iranian spelt did not alter spike morphology at all. It is concluded that the expression of the spelt syndrome depends, to a large extent, on the interactions of q with genes controlling glume tenacity and rachis fragility on other chromosomes. The genetic basis for the spelt syndrome and the apparent presence of the Q allele in Iranian spelt are discussed.
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  • 16
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    Theoretical and applied genetics 100 (2000), S. 934-941 
    ISSN: 1432-2242
    Keywords: Key words Zea mays L ; Maize ; Sugarcane mosaic virus ; SCMV ; Scm1 ; Scm2 ; AFLP ; RFLP ; SSR ; Pedigree relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sugarcane mosaic virus (SCMV) causes serious losses of grain and forage yield of maize (Zea mays L.) in Europe. Two dominant genes, Scm1 and Scm2, have been identified to confer resistance to SCMV. Scm1 is located on the short arm of chromosome 6 and Scm2 near the centromere region of chromosome 3. In the present study,resistant, partially resistant, and susceptible maize inbred lines, together with their ancestral lines, were evaluated with molecular markers to trace back the origin of Scm1 and Scm2. The banding patterns indicated that the Scm1 region, originally identified in resistant European line FAP1360A, was derived from its ancestral line FAP954A. The other two resistant European lines, D21 and D32, most likely carry the same Scm1 region, which originated from their common ancestral line A632. This Scm1 region was also present in three partially resistant lines, D09, FAP1396A and FAP693A, but not in the resistant U.S. inbred Pa405. Apart from FAP954A and A632, none of the remaining ancestral lines and none of the susceptible lines harbored the Scm1 region. The Scm2 region present in FAP1360A was obviously transmitted from its ancestral line Co125. However, the presence of the respective Scm2 region was not confirmed in the other three resistant lines (D21, D32 and Pa405), the remaining ancestral lines, and all partially resistant lines by using closely linked markers.
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  • 17
    ISSN: 1432-2242
    Keywords: Key words Map-based cloning ; RFLP ; YAC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  An ethylene-inducing xylanase (EIX) from Tricohoderma viride is a potent elicitor of ethylene biosynthesis, localized cell death and other defense responses in specific cultivars of tobacco (Nicotiana tabacum) and tomato (Lycopersicon esculentum). Wild species of tomato, such as Lycopersicon cheesmanii and Lycopersicon pennellii, do not respond to EIX treatment. The F1 progeny of a L. esculentum×L. cheesmanii and a L. esculentum×L. pennellii cross responded to EIX treatment with an increase in ethylene biosynthesis and the induction of localized cell death. The F2 progeny of the above mentioned crosses segregated 3:1 (responding:non-responding). We mapped the EIX-responding locus (Eix) to the short arm of chromosome 7 using a population of introgression lines (ILs), containing small RFLP-defined chromosome segments of L. pennellii introgressed into L. esculentum. RFLP analysis of 990 F2 plants that segregated for the introgressed segment mapped the Eix locus 0.1 cM and 0.9 cM from the flanking markers TG61 and TG131, respectively. Using the marker TG61 we isolated a yeast artificial chromosome (YAC) clone that carries 300-kb DNA segments derived from the Eix region. By mapping the ends of this YAC clone we show that it spans the Eix locus. Thus, positional cloning of the Eix locus appears feasible.
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  • 18
    ISSN: 1432-2242
    Keywords: Keywords Resistance ; Tomato powdery mildew ; Tomato ; Mapping ; Oidium lycopersicum ; RFLP ; Sequence characterised amplified region (SCAR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Lycopersicon hirsutum G1.1560 is a wild accession of tomato that shows resistance to Oidium lycopersicum, a frequently occurring tomato powdery mildew. This resistance is largely controlled by an incompletely dominant gene Ol-1 near the Aps-1 locus in the vicinity of the resistance genes Mi and Cf-2/Cf-5. Using a new F2 population (n=150) segregating for resistance, we mapped the Ol-1 gene more accurately to a location between the RFLP markers TG153 and TG164. Furthermore, in saturating the Ol-1 region with more molecular markers using bulked segregant analysis, we were able to identify five RAPDs associated with the resistance. These RAPDs were then sequenced and converted into SCAR markers: SCAB01 and SCAF10 were L. hirsutum-specific; SCAE16, SCAG11 and SCAK16 were L. esculentum-specific. By linkage analysis a dense integrated map comprising RFLP and SCAR markers near Ol-1 was obtained. This will facilitate a map-based cloning approach for Ol-1 and marker-assisted selection for powdery mildew resistance in tomato breeding.
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  • 19
    ISSN: 1432-2242
    Keywords: Key words Genomic map ; Acacia mangium ; Recombination rate ; Microsatellites ; RFLP ; Legumes ; Polyads
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  An integrated genetic linkage map, comprised of 219 RFLP and 33 microsatellite loci in 13 linkage groups, was constructed using two outbred pedigrees of Acacia mangium Willd. The linkage groups ranged in size from 23 to 103 cM and the total map length was 966 cM. Individual maps were made for each pedigree and the ordering of loci was consistent with the integrated map. The use of two independent pedigrees allowed a comparison of recombination rates between linked loci in male and female meioses as well as between parents. Differences were confined to specific regions and were not uniform across the male and female genomes or between genotypes. The heterogeneity in recombination frequencies did not result in major differences in the ordering of loci between pedigrees; hence, the integrated map provides a sound basis for QTL detection, leading to marker-assisted selection in A. mangium. It also provides a reference map for comparative genome analysis in acacias. The co-dominant markers used for mapping provide a useful resource in population studies and for quality control in acacia breeding programs. Detection of a relatively high proportion of selfs in pods derived from flowers which were not emasculated (30%), compared with emasculated flowers (0.01%), indicates that emasculation is desirable for efficient delivery of control-crossed seed in acacia breeding programs.
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  • 20
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    Theoretical and applied genetics 101 (2000), S. 613-624 
    ISSN: 1432-2242
    Keywords: Keywords Melon (Cucumis melo L.) ; Fruit ripening ; Ethylene production rate ; Postharvest fruit decay ; Shelf-life ; ACC oxidase ; ACC synthase ; SSR ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sixty three cultigens from eight market types of the melon (Cucumis melo L. subsp. melo) groups Cantaloupensis and Inodorus were evaluated for ethylene production rate, shelf-life (postharvest decay), and RFLP polymorphisms. The ethylene production rates of melon fruits at maturity and (after) postharvest decay were measured on individual genotypes. The ethylene production rates of individual genotypes ranged from undetectable to 103 nl/g per h. The mean ethylene production rates of the eight market types, ranked from highest to lowest, were Eastern U.S. type, Charentais, Western U.S. type, Long Shelf-Life cantaloupes (LSL), Galia, Ananas, Honeydew, and Casaba. Ethylene production and postharvest decay rating were positively significantly correlated (r 2=0.87, P=0.05). Orange-fleshed melon fruits produced significantly (P=0.05) more ethylene than did green- or white-fleshed types. Melon fruits with a netted rind had significantly (P=0.05 for orange-flesh fruits and 0.01 for green- or white-flesh fruits) higher ethylene production than did smooth-type fruits. Using probes made from cDNAs encoding ACC oxidase (MEL1) or ACC synthase (MEACS1) genes, RFLPs were detected melon cultigens of the eight marker types showing varying ethylene production rates and different flesh colors. Low ethylene production and green- and white-flesh color were associated (r 2=0.91; P=0.05) with the presence of a putative RFLP-MEL1 allele A 0 (15-kb), whereas high ethylene production and orange-flesh color were associated with allele B 0 (8.5-kb) in the homozygous condition, after probing MEL1 with EcoRV-digested genomic DNA. Also, after probing MEACS1 with NdeI-digested genomic DNA, RFLP polymorphism revealed five fragments denoted as A, B, C, D and E, with molecular sizes of 5.2-, 4.2-, 3.8-, 3.0- and 1.0-kb, respectively. A two-fragment pattern, AB, and a three-fragment pattern, ACE, the two predominant RFLP patterns, were also associated with low and high ethylene production, respectively. The ACE fragment pattern was also associated with orange-flesh melons. Scoring of both probes allowed for the unique classification of most melon market types consistent with ethylene production and the postharvest decay phenotypes. Therefore, these RFLPs might have utility in marker-assisted selection for the development of melons with enhanced postharvest keeping ability.
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  • 21
    ISSN: 1432-2242
    Keywords: Keywords Oryza sativa L. ; Gene mapping ; Magna porthe grisea ; Pyricularia grisea ; Disease resistance ; Complete resistance ; Resistance genes ; Pyramiding ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A framework linkage map was developed using 284 F10 recombinant inbred lines (RILs) from a ’Lemont’×’Teqing’ rice cultivar cross. Evaluation of a subset of 245 of these RILs with five races of the rice blast pathogen permitted RFLP mapping of three major resistance genes from Teqing and one major gene from Lemont. All mapped genes were found to confer resistance to at least two blast races, but none conferred resistance to all five races evaluated. RFLP mapping showed that the three resistance genes from Teqing, designated Pi-tq5, Pi-tq1 and Pi-tq6, were present on chromosomes 2, 6 and 12, respectively. The resistance gene from Lemont, Pi-lm2, was located on chromosome 11. Pi-tq1 is considered a new gene, based on its reaction to these five races and its unique map location, while the other three genes may be allelic with previously reported genes. Lines with different gene combinations were evaluated for disease reaction in field plots. Some gene combinations showed both direct effects and non-linear interaction. The fact that some of the lines without any of the four tagged genes exhibited useful levels of resistance in the field plots suggests the presence of additional genes or QTLs affecting the blast reaction segregating in this population.
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  • 22
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    Theoretical and applied genetics 100 (2000), S. 519-527 
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Triticum aestivum ; Physical mapping ; Deletion lines ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Extended physical maps of chromosomes 6A, 6B and 6D of common wheat (Triticum aestivum L. em Thell., 2n=6x=42, AABBDD) were constructed with 107 DNA clones and 45 homoeologous group-6 deletion lines. Two-hundred and ten RFLP loci were mapped, including three orthologous loci with each of 34 clones, two orthologous loci with each of 31 clones, one locus with 40 clones, two paralogous loci with one clone, and four loci, including three orthologs and one paralog, with one clone. Fifty five, 74 and 81 loci were mapped in 6A, 6B and 6D, respectively. The linear orders of the mapped orthologous loci in 6A, 6B and 6D appear to be identical and 65 loci were placed on a group-6 consensus physical map. Comparison of the consensus physical map with eight linkage maps of homoeologous group-6 chromosomes from six Triticeaespecies disclosed that the linear orders of the loci on the maps are largely, if not entirely, conserved. The relative distributions of loci on the physical and linkage maps differ markedly, however. On most of the linkage maps, the loci are either distributed relatively evenly or clustered around the centromere. In contrast, approximately 90% of the loci on the three physical maps are located either in the distal one-half or the distal two-thirds of the six chromosome arms and most of the loci are clustered in two or three segments in each chromosome.
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  • 23
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    Theoretical and applied genetics 101 (2000), S. 860-864 
    ISSN: 1432-2242
    Keywords: Key words Melon ; AFLP ; RFLP ; RAPD ; Genetic similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Three different types of molecular markers, RAPD, AFLP and RFLP were used to measure genetic diversity among six genotypes of Cucumis melo L. Each line represented a different melon genotype: Piel de Sapo, Ogen, PI161375, PI414723, Agrestis and C105. A number of polymorphic RAPD, AFLP and RFLP bands were scored on all materials and the genetic similarity measured. Clustering analysis performed with the three types of markers separated the genotypes into two main groups: (1) the sweet type, cultivated melons and (2) the exotic type, not cultivated melons. While the data obtained suggest that all three types of markers are equally informative, AFLPs showed the highest efficiency in detecting polymorphism.
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  • 24
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    Theoretical and applied genetics 101 (2000), S. 948-955 
    ISSN: 1432-2242
    Keywords: Key words Theobroma cacao L. ; AFLP ; Microsatellites ; RFLP ; High-density genetic map
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The first linkage map established by Lanaud et al. (1995) was used as a starting point to produce a high-density molecular linkage map. A mapping population of 181 progenies resulting from a cross between two heterozygous genotypes, a Forastero and a Trinitario (hybrid between Forastero and Criollo), was used for the linkage analysis. A new DNA isolation protocol was established, which allows enough good quality DNA to construct a genetic map with PCR-based markers. The map comprises 424 markers with an average spacing between markers of 2.1 cM. The marker types used were five isozymes, six loci from known function genes, 65 genomic RFLPs, 104 cDNA RFLPs, three telomeric probes, 30 RAPDs, 191 AFLPs and 20 microsatellites. The use of new marker types, AFLP and microsatellites, did not disturb the original order of the RFLP loci used on the previous map. The genetic markers were distributed over ten linkage groups and cover 885.4 cM. The maximum distance observed between adjacent markers was 16.2 cM, and 9.4% of all loci showed skewed segregation.
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  • 25
    ISSN: 1432-2242
    Keywords: Key words Sugarcane ; Rust resistance gene ; Comparative mapping ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A major rust resistance gene has been identified in a self-progeny of the sugarcane cultivar R570. Until now, this gene was known to be linked to a marker revealed by the sugarcane probe CDSR29 but unassigned to any linkage group of the current genetic map. We used synteny relationships between sugarcane and three other grasses in an attempt to saturate the region around this rust resistance gene. Comparison of sugarcane, sorghum, maize and rice genetic maps led to the identification of homoeologous chromosome segments at the extremity of sorghum linkage group D, rice linkage group 2, maize linkage group 4 and in the centromeric region of maize linkage group 5. One hundred and eighty-four heterologous probes were selected and tested for cross-hybridization with sugarcane DNA; 106 produced a good hybridization signal and were hybridized on 88 individuals of the R570 selfed progeny. Two hundred and seventeen single-dose markers were added to the R570 genetic map, of which 66% mapped to linkage group VII, together with the rust resistance gene. This gene has now been mapped to the end of a co-segregating group consisting of 19 RFLP markers. None of the mapped loci were located closer to the gene than CDSR29. The gene thus appears to reside at the edge of a ’’synteny cluster’’ used to describe the different grass genomes.
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  • 26
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    Journal of thermal analysis and calorimetry 60 (2000), S. 1081-1091 
    ISSN: 1572-8943
    Keywords: second law of thermodynamics ; temperature ; thermometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A brief outline of the history of development of the temperature concept in physics is given. Simultaneously, some persisting imperfections in the conceptual basis of classical thermodynamics closely related to the first and the second law of thermodynamics are discussed.
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  • 27
    ISSN: 1573-1561
    Keywords: Allelopathy ; autotoxicity ; activated charcoal ; cucumber ; Cucumis sativus L ; 2,4-dichlorobenzoic acid ; organic acids ; photoperiod ; temperature ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In order to elucidate the effects of temperature and photoperiod on the quality and quantity of plant root exudates, a Japanese cucumber (Cucumis sativus, cv. Shougoin-Aonaga-Fushinari) was grown hydroponically in growth chambers under controlled temperature and photoperiod conditions with or without the addition of activated charcoal (AC) to the nutrient solutions. Fresh AC was used to trap the organic compounds exuded from cucumber roots every two weeks. Cucumber plants without AC were severely retarded in root growth and in the accumulation of dry matter, especially at high temperature and long photoperiod, compared to those with AC. The growth inhibitors, adsorbed on the AC or accumulated in the nutrient solution without AC, were extracted by organic solvents and analyzed by GC-MS. Benzoic acid and its derivatives, cinnamic acid derivatives, and fatty acids were identified. The rate of root exudation in vegetative and reproductive stages for some of these organic acids increased with the elevation of temperature and the elongation of photoperiod, and the mean rate was two or more times higher than the minimum exudation at low temperature with short photoperiod. Some of the identified compounds significantly inhibited the germination and/or root growth of lettuce and cucumber.
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  • 28
    ISSN: 1573-4943
    Keywords: Ribonuclease A ; limited proteolysis ; temperature ; guanidine hydrochloride ; unfolding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Moderate temperatures or low concentrations of denaturants diminish the catalytic activity of some enzymes before spectroscopic methods indicate protein unfolding. To discriminate between possible reasons for the inactivation of ribonuclease A, we investigated the influence of temperature and guanidine hydrochloride on its proteolytic susceptibility to proteinase K by determining the proteolytic rate constants and fragment patterns. The results were related to changes of activity and spectroscopic properties of ribonuclease A. With thermal denaturation, the changes in activity and in the rate constants of proteolytic degradation coincide and occur slightly before the spectroscopically observable transition. In the case of guanidine hydrochloride-induced denaturation, however, proteolytic resistance of ribonuclease A initially increases accompanied by a drastic activity decrease far before unfolding of the protein is detected by spectroscopy or proteolysis. In addition to ionic effects, a tightening of the protein structure at low guanidine hydrochloride concentrations is suggested to be responsible for ribonuclease A inactivation.
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  • 29
    ISSN: 1432-2242
    Keywords: Key words Genetic relationship ; Maize ; Pedigree ; RFLP ; SSR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The genetic relationship between inbreds i and j can be estimated from pedigree or from molecular marker data. The objectives of this study were to: (1) determine whether pedigree, restriction fragment length polymorphism (RFLP), and simple sequence repeat (SSR) data give similar estimates of parental contribution and coefficient of coancestry (f ij ) among a set of maize (Zea mays L.) inbreds, and (2) compare the usefulness of RFLP and SSR markers for estimating genetic relationship. We studied 13 maize inbreds with known pedigrees. The inbreds were genotyped using 124 RFLP and 195 SSR markers. For each type of marker, parental contributions were estimated from marker similarity among an inbred and both of its parents, and were subsequently used to estimate f ij . Estimates of parental contribution differed significantly (α〈0.05) between pedigree data and either type of marker, but not between the marker systems. The RFLP estimates of parental contribution failed to sum to 1.0, reflecting a higher frequency of non-parental bands with RFLP than with SSR markers. The f ij estimated from pedigree, RFLP, and SSR data were highly correlated (r=0.87–0.97), although significant differences were found among the three sets of f ij estimates. We concluded that pedigree and marker data often lead to different estimates of parental contribution and f ij , and that SSR markers are superior to RFLP markers for estimating genetic relationship. A relevant question is whether or not the inbreds previously genotyped with an older marker system (e.g., RFLP) need to be re-analyzed with a newer marker system (e.g., SSR) for the purpose of estimating genetic relationship. Such re-analysis seems unnecessary if data for the same type of marker are available for a given inbred and both of its parents.
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  • 30
    ISSN: 1432-2242
    Keywords: Key words Karnal bunt ; Repetitive elements ; Genome diversity ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Neovossia indica (Tilletia indica), causing Karnal bunt of wheat, affects major wheat growing regions all over the world. Karnal bunt ranks as one of the major diseases of wheat causing quality losses and monetary losses due to international quarantine regulations. The present work is the first report of a genetic diversity analysis of Indian isolates of N. indica. A library of N. indica isolate Ni7 was constructed in a λZAPII system, and three repetitive elements were identified for molecular analysis. These repetitive elements generated complex hybridization profiles producing fingerprint patterns of all seven isolates. Copy-number estimation of these three elements, pNiR9, pNiR12 and pNiR16, indicated the presence of 32, 61 and 64 copies, respectively. Cluster analysis based on hybridization patterns grouped together moderately virulent isolates Ni1, Ni7 and Ni8, thus suggesting a positive correlation between virulence typing and cluster analysis based on molecular data. Variability analysis of N. indica isolates will aid in checking new resistant sources in host germplasm.
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  • 31
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    Molecular genetics and genomics 263 (2000), S. 925-933 
    ISSN: 1617-4623
    Keywords: Key words S-like RNase ; Phosphate starvation ; Senescence ; RFLP ; Almond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA for an S-like RNase (RNase PD2) has been isolated from a pistil cDNA library of Prunus dulcis cv. Ferragnés. The cDNA encodes an acidic protein of 226 amino acid residues with a molecular weight of 25 kDa. A potential N-glycosylation site is present at the N-terminus in RNase PD2. A signal peptide of 23 amino acid residues and a transmembrane domain are predicted. The two active-site histidines present in enzymes of the T2/S RNase superfamily were detected in RNase PD2. Its amino acid sequence shows 71.2% similarity to RNS1 of Arabidopsis and RNase T2 of chickpea, respectively. Northern blotting and RT-PCR analyses indicate that PD2 is expressed predominantly in petals, pistils of open flowers and leaves of the almond tree. Analyses of shoots cultured in vitro suggested that the expression of RNase PD2 is associated with phosphate starvation. Southern analysis detected two sequences related to RNase PD2 in the P. dulcis genome. RFLP analysis showed that S-like RNase genes are polymorphic in different almond cultivars. The PD2 gene sequence was amplified by PCR and two introns were shown to interrupt the coding region. Based on sequence analysis, we have defined three classes of S-like RNase genes, with the PD2 RNase gene representing a distinct class. The significance of the structural divergence of S-like RNase genes is further discussed.
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  • 32
    ISSN: 1608-3237
    Keywords: poly-β-hydroxybutyric acid ; Yersinia pseudotuberculosis ; Listeria monocytogenes ; temperature ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative investigation of the intracellular content of poly-β-hydroxybutyric acid showed that Yersinia pseudotuberculosis strains accumulated, on the average, lower amounts of this reserve substance than Listeria monocytogenes strains. The intracellular pool of poly-β-hydroxybutyric acid was responsible for the growth of the bacteria at low temperatures (4–6°C) in the absence of any exogenous carbon and energy source.
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  • 33
    ISSN: 1608-3407
    Keywords: red microalgae ; collection of algae ; maintenance conditions ; darkness ; temperature ; chlorophyll fluorescence ; phycobiliproteins ; viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of light and temperature conditions on the maintenance of some red microalgae (order Porphyridiales) in collections were studied. Periodical subculturing on solid and liquid media was used for maintenance. Halophilic species P. aeruginosa, P. cruentum, and P. sordidum were lost in 2.5 months if kept in darkness. The viability of algae in the dim light slightly declined in 4–5 months and was species-dependent. The results were compared with earlier obtained data on mesophilic Chlorococcales. For the green algae, darkness proved to be the optimal condition, while their viability markedly decreased at light. It was suggested that this discrepancy was caused by the presence of phycobiliproteins in the cells of red algae. Dim light conditions are optimal for the synthesis of phycobiliproteins, which are rapidly destroyed in darkness, thus leading to cell death.
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  • 34
    ISSN: 1573-5125
    Keywords: diapause ; Diaptomus ; permanent environment ; photoperiod ; pond chemistry ; proximate cues ; temperature ; temporary environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field and laboratory studies were carried out between 1995 and 1997 on four populations of Diaptomus leptopus found in seasonally temporary, occasionally temporary, and a permanent environment to assess the relative importance of photoperiod and temperature regimes versus other proximate local cues in inducing diapause egg production. Patterns of diapausing and subitaneous egg production were determined by observation of individual females bearing clutches that were produced in the field. A laboratory common-garden experiment was performed to assess the effects of four different regimes of temperature and photoperiod on the induction of diapause. Patterns of diapausing egg production differed among ponds: diapause occurred early in the seasonally temporary environment and occurred rarely in the permanent environment. In the common-garden experiment, populations exhibited substantial changes in the onset of diapause when compared to patterns found under field conditions. These results provide indirect evidence that the different populations respond to available cues of environmental change in different ways in nature, or that environmental cues vary among habitats.
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  • 35
    ISSN: 1573-5125
    Keywords: body size ; chlorophyll concentration ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal variation in length of the most abundant copepod species in the lagoon of Venice were compared and the relative influence of temperature, chlorophyll concentration and salinity examined. Temperature seems to be the primary factor influencing copepod body length in the lagoon of Venice, but the different species vary markedly in their response. Calanoid copepods (Acartia clausi, A. tonsa, Paracalanus parvus and Centropages ponticus) showed a more definite trend of size variation with temperature than the cyclopoids (Oithona nana and O. similis) and the harpacticoid Euterpina acutifrons. The size of the poecilostomatoids Oncaea media and O. subtilis was not affected by temperature, and was almost constant over time. Differences in the metabolic rates, longevity and specialization of calanoid, cyclopoid and harpacticoid copepods could explain their different responses to temperature.
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  • 36
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    Aquatic ecology 34 (2000), S. 227-242 
    ISSN: 1573-5125
    Keywords: cladocerans ; demography ; Microcystis aeruginosa ; rotifers ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of selected rotifers and cladocerans to Microcystis aeruginosa, offered as colonies and single cells, was compared to that on a diet of Chlorella vulgaris using the life table demography approach. The test zooplankton species were Simocephalus vetulus, Daphnia carinata, Moina macrocopa, Scapholeberis kingi, Ceriodaphnia cornuta, Brachionus calyciflorus and Hexarthra mira. To detect the development of resistance to toxins from Microcystis in zooplankton, in addition to the laboratory cultured strain of Ceriodaphnia cornuta, another strain of the same species was also used (designated as C. cornuta 2, this was collected from a pond containing Microcystis and cultured in the laboratory on Chlorella for a few weeks prior to experimentation). Experiments were conducted at 20 °C and 30 °C. Survivorship was high on Chlorella in most species but low on diets of Microcystis. Except for C. cornuta 2, S. kingi and S. vetulus, all other test species were adversely affected by Microcystis. The ability to utilise Microcystis improved at 30 °C in M. macrocopa, D. carinata and H. mira. The longest mean lifespan was recorded for C. cornuta 2 (25.3 ± 4.86 d) and the lowest for B. calyciflorus (0.58 ± 0.05 d). The highest net reproductive rate was observed for C. cornuta 1 (44.9 ± 4.88) and the longest generation time of 26.6 ± 2.13 d for S. vetulus. Among the cladocerans that showed positive values of population growth rate (r), M. macrocopa had the highest of 0.96 ± 0.04 per day.
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  • 37
    ISSN: 1573-5176
    Keywords: desiccation ; growth ; growth model ; inorganic carbon ; nutrients ; photoperiod ; photosynthesis ; pigments ; Porphyra linearis ; PPF ; respiration ; temperature ; water velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of environmental parameters on the growthof Porphyra linearis gametophytes was examinedunder controlled conditions, and related to themultilinear regression growth model recently developedfor this seaweed under coastal conditions in theeastern Mediterranean. Growth chambers, a gradienttable, special culture devices and analytical methodswere combined for this culture study.The major factors significantly controlling thegrowth rate of the P. linearis gametophytein glass dishes were: photoperiod, temperature, agein culture, photosynthetic photon flux (PPF), salinityand water dynamics. Maximal growth occurred underdaylength of 12 h, medium temperature (15–20 °C), low PPF (70–140 μmol photon m-2s-1), ambient salinity (30–40 ppt), 1–3 h ofdaily air exposure, and water velocity of 4 cm s-1.Photosynthesis and respiration rates weredominantly affected by daylength and temperature,while the concentration of pigments was dominantlyaffected by PPF and temperature.These conditions correspond well to the optimalnatural growth environment of this local species andare in agreement with the optimum estimated throughthe recently developed outdoor mathematical growthmodel.
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  • 38
    ISSN: 1572-9788
    Keywords: mapping ; morphology ; QTL ; RFLP ; spike density ; Triticeae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quantitative trait loci (QTLs) for three traits related to ear morphology (spike length, number of spikelets, and compactness as the ratio between number of spikelets and spike length) in wheat (Triticum aestivum L.) were mapped in a doubled-haploid (DH) population derived from the cross between the cultivars Courtot and Chinese Spring. A molecular marker linkage map of this cross that had previously been constructed based on 187 DH lines and 380 markers was used for QTL mapping. The genome was well covered (85%) except chromosomes 1D and 4D and a set of anchor loci regularly spaced (one marker each 15.5 cM) were chosen for marker regression analysis. The presence of a QTL was declared at a significance threshold α = 0.001. The population was grown in one location under field conditions during three years (1994, 1995 and 1998). For each trait, 4 to 6 QTLs were identified with individual effects ranging between 6.9% and 21.8% of total phenotypic variation. Several QTLs were detected that affected more than one trait. Of the QTLs 50% were detected in more than one year and two of them (number of spikelets on chromosome 2B, and compactness on chromosome 2D) emerged from the data from the three years. Only one QTL co-segregated with the gene Q known to be involved in ear morphology, namely the speltoid phenotype. However, this chromosome region explained only a minor part of the variation (7.5–11%). Other regions had a stronger effect, especially two previously unidentified regions located on chromosomes 1A and 2B. The region on the long arm of chromosome 1A was close to the locus XksuG34-1A and explained 12% of variation in spike length and 10% for compactness. On chromosome 2B, the QTL was detected for the three traits near the locus Xfbb121-2B. This QTL explained 9% to 22% of variation for the traits and was located in the same region as the gene involved in photoperiod response (Ppd2). Other regions were located at homoeologous positions on chromosomes 2A and 2D.
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  • 39
    ISSN: 1572-9788
    Keywords: late blight ; durable resistance ; RFLP ; AFLP ; SSR ; CAPS ; QTL mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Six F1 populations produced from crosses between two Solanum microdontum genotypes and three S. tuberosum genotypes have been assessed for resistance to Phytophthora infestans (late blight; LB) in the field and proved to segregate for P. infestans resistance. The six populations were subjected to genetic mapping using AFLP markers in combination with a core map consisting of RFLPs and a few PCR-based markers. The two S. microdontum parents MCD167 and MCD178 harbour different alleles contributing to resistance. In the MCD167 set of populations a major QTL contributing to resistance was located on chromosome 4. This locus was not detected in the MCD178 set of populations. In the latter set of populations, a major QTL for resistance was detected on chromosome 10. This locus for resistance was not detected in the MCD167 set of populations. A third QTL contributing strongly to resistance was detected on chromosome 5. However, this locus was not consistently detected in all populations. For the loci on chromosome 5 and 10, segregation for resistance alleles from the susceptible parents was also observed. The results provide a starting point for future combinations of genes, to predict the value of each combination and finally to obtain potato germplasm carrying high levels of durable resistance to LB.
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  • 40
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    Molecular breeding 6 (2000), S. 105-111 
    ISSN: 1572-9788
    Keywords: carbohydrates ; genetic mapping ; oil ; protein ; QTL ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sucrose is a primary constituent of soybean (Glycine max) seed; however, little information concerning the inheritance of seed sucrose in soybean is available. The objective of this research was to use molecular markers to identify genomic regions significantly associated with quantitative trait loci (QTL) controlling sucrose content in a segregating F2 population. DNA samples from 149 F2 individuals were analyzed with 178 polymorphic genetic markers, including RFLPs, SSRs, and RAPDs. Sucrose content was measured on seed harvested from each of 149 F2:3 lines from replicated field experiments in 1993 and 1995. Seventeen marker loci, mapping to seven different genomic regions, were significantly associated with sucrose variation at P〈0.01. Individually, these markers explained from 6.1% to 12.4% of the total phenotypic variation for sucrose content in this population. In a combined analysis these genomic regions; explained 53% of total variation for sucrose content. No significant evidence of epistasis among QTLs was observed. Comparison of our QTL mapping results for sucrose content and those previously reported for protein and oil content (the other major seed constituents in soybean), suggests that seed quality traits are inherited as clusters of linked loci or that `major' QTLs with pleiotropic effects may control all three traits. Of the seven genomic regions having significant effects on sucrose content, three were associated with significant variation for protein content and three were significantly associated with oil content.
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  • 41
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    Aquaculture international 8 (2000), S. 513-530 
    ISSN: 1573-143X
    Keywords: great scallop (Pecten maximus) ; hatchery ; metamorphosis ; seawater flow ; spat development ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Variations in growth and survival of hatchery-reared post-metamorphicjuveniles of great scallop Pecten maximus prompted anexamination of settlement and postlarval development. The effects ofseawater flow and temperature on great scallop metamorphosis andpostlarvae were studied over a 4–5 week period. In allexperiments, and regardless of environmental conditions, great scallopmetamorphosed after a 2–3 week period with values of 35 to70%. Subsequently, spat numbers increased slightly. Spatmortality generally occurred from the third week onward and reachedlevels as high as 30% by the fifth week under standardconditions. At 20 °C, however, 60% mortality levels wererecorded. Differences in spat growth rate, ranging from 37 to 45 μmday−1, were noticed at different seawater flow ratesbut no clear tendency could be discerned. Temperature affected spatgrowth with an increase in size from 24 μm day−1 at15 °C to 35 μm day−1 at 18 °C. Conversely,growth was suppressed at 20 °C (14 μm day−1).For optimal metamorphosis and postlarval development in great scallop, aseawater flow of 4.3 L h−1 per sieve and a temperatureof 15 °C are recommended.
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  • 42
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    European journal of plant pathology 106 (2000), S. 179-186 
    ISSN: 1573-8469
    Keywords: geminivirus ; RFLP ; PCR ; PAGE ; differentiation ; dot-blot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tomato yellow leaf curl disease is spreading in southern Europe, where it has quickly become a serious problem. In recent years, several virus isolates have been characterised. Although with some genetic variability, all isolates found in Europe belong to one of two species Tomato yellow leaf curl-Sardinia (TYLCV-Sar) or Tomato yellow leaf curl-Israel (TYLCV-Is). Several methods were tested to identify and type TYLCV isolates from field samples: (1) RFLP of a DNA fragment amplified from the coat protein gene; (2) PAGE of a fragment amplified from the C2 gene; (3) dot-blot hybridisation. All methods enabled the detection of the TYLCVs and provided good indications for attributing them to one species or the other. However, for typing purposes, the RFLP method was the most reliable, due to the easily recognisable pattern produced by the two virus species present in Europe. Dot-blot hybridisation is less expensive for identifying TYLCVs in large numbers of samples, particularly when a mixture of two probes is used. PAGE of the C2 fragment is the fastest of the methods tested.
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  • 43
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    Evolutionary ecology 14 (2000), S. 627-643 
    ISSN: 1573-8477
    Keywords: adaptation ; Bergmann's rule ; clutch size ; egg size ; physiological constraint ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Organisms and parts of an organism like eggs or individual cells developing in colder environments tend to grow bigger. A unifying explanation for this Bergmann's rule extended to ectotherms has not been found, and whether this is an adaptive response or a physiological constraint is debated. The dependence of egg and clutch size on the mother's temperature environment were investigated in the yellow dung fly Scathophaga stercoraria. Smaller eggs were laid at warmer temperatures in the field and the laboratory, where possible confounding variables were controlled for. As clutch size at the same time was unaffected by temperature, this effect was not due to a trade-off between egg size and number. Temperature-dependent egg sizes even persisted within individuals: when females were transferred to a cooler (warmer) environment, they laid third-clutch eggs that were larger (smaller) than their first-clutch eggs. The fitness consequences of these temperature-mediated egg sizes were further investigated in two laboratory experiments. Neither egg and pre-adult survivorship nor larval growth rate were maximized, nor was development time minimized, at the ambient temperature corresponding to the mother's temperature environment. This does not support the beneficial acclimation hypothesis. Instead, this study yielded some, but by no means conclusive indications of best performance by offspring from eggs laid at intermediate temperatures, weakly supporting the optimal temperature hypothesis. In one experiment the smaller eggs laid at 24°C had reduced survivorship at all ambient temperatures tested. Smaller eggs thus generally performed poorly. The most parsimonious interpretation of these results is that temperature-mediated variation in egg size is a maternal physiological response (perhaps even a constraint) of unclear adaptive value.
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  • 44
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    Powder metallurgy and metal ceramics 39 (2000), S. 599-602 
    ISSN: 1573-9066
    Keywords: solid-phase reaction ; solubility ; temperature ; cobalt silicides ; boron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The system Co ― Si ― B is promising for development of new soft magnetic materials. We studied the effect of boron on the structure and composition of cobalt silicides during solid-phase reaction of powders of the starting components under a 3·10−3 Pa vacuum in the temperature range 200°C to 1300°C for boron content from 0.5 mass% to 7.7 mass% by differential thermal analysis, metallographic analysis, x-ray analysis, and electron-probe microanalysis. We established that boron is not soluble in cobalt silicides. Formation of ternary chemical compounds is typical for the Co ― Si ― B system.
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  • 45
    ISSN: 1573-5036
    Keywords: Arctic ; Cerastium alpinum ; nitrogen source ; nitrogen-uptake ; organic N ; polar-desert plants ; Saxifraga caespitosa ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Polar-desert plants experience low average air temperatures during their short growing season (4–8 °C mean July temperature). In addition, low availability of inorganic nitrogen in the soil may also limit plant growth. Our goals were to elucidate which N sources can be acquired by polar-desert plants, and how growth and N-uptake are affected by low growth temperatures. We compared rates of N-uptake and increases in mass and leaf area of two polar-desert species (Cerastium alpinum L. and Saxifraga caespitosa L.) over a period of 3 weeks when grown at two temperatures (6 °C vs. 15 °C) and supplied with either glycine, NH4 + or NO3 −. At 15 °C, plants at least doubled their leaf area, whereas there was no change in leaf area at 6 °C. Measured mean N-uptake rates varied between 0.5 nmol g−1 root DM s−1 on glycine at 15 °C and 7.5 nmol g−1 root DM s−1 on NH4 + at 15 °C. Uptake rates based upon increases in mass and tissue N concentrations showed that plants had a lower N-uptake rate at 6 °C, regardless of N source or species. We conclude that these polar-desert plants can use all three N sources to increase their leaf area and support flowering when grown at 15 °C. Based upon short-term (8 h) uptake experiments, we also conclude that the short-term capacity to take up inorganic or organic N is not reduced by low temperature (6 °C). However, net N-uptake integrated over a three-week period is severely reduced at 6 °C.
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  • 46
    ISSN: 1573-5060
    Keywords: adaptedness ; morphological and genetic differentiation ; Oryza sativa L. ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Indica and Japonica differentiation under the species of Oryza sativa L. has been documented using morphological characters, isozyme and DNA markers. We illustrate marker assisted analysis of genetic differentiation with a sample of RFLP and isozyme data from 111 accessions of rice lines and compare it to morphological differentiation based on Cheng and Wang' morphological character index. The results lead to three main conclusions: (1) Among the 92 polymorphic cloned probes deliberately selected, 41 were highly associated with Indica-Japonica differentiation, suggesting such differentiation was an accumulative process of gene change at multiple loci; (2) There exist two main types of relationships between morphological and genetic differentiation. For well differentiated Indica and Japonica (as the case in the control subset), morphology and genomic constitutions are synchronously specialized. For incompletely differentiated rice lines (as the case in the subset of DH lines), morphological differentiation and genetic differentiation are asynchronous. (3)Synthetic or incompletely differentiated rice lines with different genomic constitutions are often adapted to specific environments. These results indicate that marker alleles provide applied breeders with effective ways to identify, track, and incorporate regions of chromosomes governing adaptedness to specific target environments into improved cultivars.
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  • 47
    ISSN: 1573-5060
    Keywords: agronomic characters ; geneticmapping ; quantitative trait loci ; QTL ; RFLP ; Secale cereale L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using the marker information of 275 F2 plants quantitative traits determining morphological and yield characters were studied analyzing F3progenies grown in four different experiments at three sites. The map constructed contains 113 markers including the major dwarfing gene Ddw1 with an average distance of about 10 cM between adjacent markers. Of the 21 QTLs detected ten were found to map on chromosome 5RL in the region of Ddw1. Beside the expected effects on plant height and peduncle length that are most probably due to the presence of the major dwarfing gene, additional effects on yield characters and flowering time were discovered in that region which may be caused by pleiotropic effects of Ddw1. An additional supposed gene cluster consisting of four QTLs controlling flowering time and yield components was discovered in the centromere region of chromosome 2R. Further loci are distributed on chromosomes 1R (1), 4R (1) 6R (3) and 7R (1). The map positions of the quantitative trait loci detected in rye are discussed in relation to major genes or QTLs determining agronomically important traits in other cereals.
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  • 48
    ISSN: 1573-5060
    Keywords: gene diversity ; population genetics ; RFLP ; Theobroma cacao L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The genetic structure of 175 genotypes of Theobroma cacao L. was investigated using 27 RFLP/cDNA loci. The number of alleles per locus was never higher than four and a high genetic diversity was found. Criollo genotypes appeared differentiated from Forastero genotypes. A deficiency of heterozygotes was found in all populations and some alleles were fixed in some populations. Within population gene diversity was high. When four morphological groups were considered, Upper Amazon Forastero was the most polymorphic and diverse population. Almost all the alleles of the whole species could be found within this group. Observed heterozygosity was the highest within Criollo and Trinitario populations but a certain proportion of homozygous genotypes was present in all groups.
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  • 49
    ISSN: 1573-5109
    Keywords: Chinese landraces ; chloroplast ; mitochondria ; phylogeny ; RFLP ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Restriction fragment-length polymorphism (RFLP) of chloroplast and mitochondrial DNA of many soybean landraces were analyzed to characterize their cytoplasmic genome and to consider the diversity and phylogeny of soybean in China. Three chloroplast and five mitochondrial types were distinguished, and seven cytoplasmic genome types were observed in different combinations in specimens collected from China. The cytoplasmic genome diversity was higher at the Yangtze River Valley. The main group of cytoplasmic genomes was composed of five types related phylogenetically and occurred in the southern region of China. Two unique types were very different in cytoplasmic genome constitution from each other and from the main group. They were considered to be derived from wild plants with the same cytoplasmic genome and to occur in two remote regions, the northern region and the Yangtze River Valley of China, respectively. Therefore, when considered with regard to the cytoplasmic genome of soybean landraces detected in China, seven genome types are distinguished, some types may be assumed to have arisen in wild soybean before domestication; and the Yangtze River Valley is the center of cytoplasmic diversity of the soybean.
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  • 50
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    Hydrobiologia 419 (2000), S. 141-148 
    ISSN: 1573-5117
    Keywords: Crustacea ; Ostracoda ; Krithe praetexta praetexta ; life cycle ; ontogeny ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature on growth rate, shell size and shell shape in Krithe praetexta praetexta (Sars) was studied in four thermocultures. From July 1995 to June 1996, the cultures were kept in a continuously flowing open system pumping water from the intermediate watermass of the Gullmarn fjord, west coast of Sweden. Three cultures were kept at constant temperatures of 5, 10 and 14 °C, respectively. The fourth (reference) culture largely followed the natural variation in temperature. At the termination of the experiment, all living ostracods from a 125 μm sieve were sampled from the cultures. Population age structures were analysed for the various thermocultures of K. praetexta praetexta. These were more shifted towards later ontogenetic stages with higher temperature, i.e. the ontogenetic development was more rapid in the warmer cultures. An alternative explanation is due to diapause causing cohorts to accumulate in some ontogenetic stages only when the temperature is constant. The differences in shell size of K. praetexta praetexta among the thermoconstant cultures were not statistically significant.
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  • 51
    ISSN: 1573-5117
    Keywords: Chirocephalus ; metabolic potential ; intermittent lake ; ecology ; physiology ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electron transport system (ETS) activity was measured in Chirocephalus croaticus from the intermittent lake, Petelinjsko Jezero. The ETS activities were measured at 5, 10, 15, 20, and 25 °C, and were studied separately in juveniles, females and males. Juveniles had significantly higher activity than adults at a standard temperature of 20 °C. The mass-specific ETS activity decreased with increasing size of the animals; the value b was 0.787. Respiration rates (R) were determined at 20 °C and the ratio ETS/R (±standard deviation) for C. croaticus was 1.43±0.46 (n=38). ETS activity increased with temperature. Females had higher Q10 than males in higher temperature range (t-test; t=2.50; d.f.=8; p〈0.05). Activation energy Ea was higher for females than males (t-test; t=2.35; d.f.=8; p〈0.05). Females exhibited lower ETS activity than males over the lower temperature range, but their ETS could function more efficient at higher temperature.
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  • 52
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    Environmental biology of fishes 57 (2000), S. 113-115 
    ISSN: 1573-5133
    Keywords: photoperiod ; temperature ; spawning ; larva rearing ; larva food
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adult fish of a freshwater population of the Iberian endangered cyprinodontid Aphanius iberus, were induced to reproduce at salinities of 5, 15, 30, 45 and 60 ppt. For each salinity five 30 l aquaria were used, each one including a male and two females. Maturity and spawning outside the natural season, were obtained at conditions of 22 to 28°C and a photoperiod of 14L:10D. The larvae were fed with rotifers Brachionus plicatilis and Synchaeta cecilia valentina. Experiment lasted 40 days. The first spawning occurred on the 17th day at 45 ppt of salinity and the first embryos hatched on the 34th day at 5 and 15 ppt salinity. The final average number of larvae per aquarium ranged from 5.2 (45 ppt salinity) to 10.8 (15 ppt salinity). No significant differences were found between the average values at different salinities (p〈0.01).
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  • 53
    ISSN: 1573-5133
    Keywords: deep pools ; young salmonids ; habitat use ; habitat availability ; temporal variation ; temperature ; winter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There was a pronounced decline in activity of young pool-dwelling Atlantic salmon, Salmo salar, and brown trout, Salmo trutta, as the water temperatures dropped in the autumn and early winter, and the fish switched from a predominantly diurnal towards a nocturnal activity pattern. Such a switch in activity pattern has previously been observed in young brown trout, but the present study is the first documentation for juvenile Atlantic salmon under natural conditions. Juvenile fish fed actively even when water temperatures were below 0°C, although foraging behaviour at near-freezing temperatures was recorded exclusively during night surveys. This indicates that other proximate factors, in addition to water temperature, affect the activity of young salmon and trout in rivers. Trout kept feeding positions significantly higher above bottom than salmon in August and September, but both species reduced the height above bottom at the onset of winter, possibly due to reduced swimming performance and lowered food availability in the upper part of the water column.
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  • 54
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    Hydrobiologia 441 (2000), S. 55-62 
    ISSN: 1573-5117
    Keywords: climate change ; temperature ; mayflies ; Cloeon dipterum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the mayfly Cloeon dipterum from 48 ponds (3000 l fibre-glass tanks of 1 m depth) were monitored over the course of 1 year. To simulate possible patterns of climatic change, the ponds were subject to three temperature treatments: continuous heating to 3 °C above ambient; heating to 3 °C above ambient during the summer only; and no heating. Further experimental complexity included enhanced nutrient input into the ponds and the presence or absence of fish, giving a factorial combination of 3 temperature regimes × 2 nutrient levels × presence/absence of fish predation. Few nymphs were found in the presence of fish. Where fish were absent, the temperature treatments did not significantly affect nymph abundances, and only marginally influenced mean nymph body-lengths. In contrast, the nutrient treatment had significant effects on both nymph abundance and size, with greater numbers of generally larger nymphs occurring in those fish-free ponds receiving additional nutrients. Adult emergence began earlier in the year from the heated ponds, particularly those ponds receiving additional nutrients. Adult body-length differed between temperature treatments, but consistent patterns were difficult to ascertain because of interactions with nutrient treatment and seasonal effects. Our results show that during the short term at least, elevated temperature as a simulation of climate change does not have an overwhelming influence on either mayfly abundance or size. The influence of temperature is subtle and subject to complex interaction with other habitat variables. We therefore suggest that the direct consequences of small changes in temperature will likely be of little significance to C. dipterum, relative to indirect effects operating through interactions with predation and nutrient input.
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  • 55
    ISSN: 1573-5117
    Keywords: Meganyctiphanes norvegica ; respiration ; temperature ; vertical migration ; Kattegat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Alkor-Deep (140 m), which forms part of a depression system in the northern Kattegat channel east of the island of Læsø (Denmark), is the location of a self sustaining population of Northern krill, Meganyctiphanes norvegica (Euphausiacea). This population is exposed to one of the most pronounced thermal gradients within the distributional range of this pelagic crustacean. During summer, the temperature of the water column ranges between 4 and 6 in the deep to 16 °C near the surface which results in the krill being exposed to temperature differences of 8–10 °C during diel vertical migration. Oxygen consumption rates were used to investigate the physiological adaptation of the animal to such gradients in temperature. The rates were found to increase exponentially from 31 μmol O2 h-1 gdw -1 at 4 °C to 72 μmol O2 h-1 gdw -1 at 16 °C, giving a Q 10-value of 2.0, and indicating that physiological adaptation to varying thermal conditions does not take place. Behavioural adaptations are discussed which may help the krill to cope with large temperature gradients in their environment.
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  • 56
    ISSN: 1573-5117
    Keywords: Cercopagis ; invasion ; Baltic Sea ; depth ; temperature ; salinity ; morphological variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The onychopod cladoceran Cercopagis that recently invaded the Baltic Sea is reported from new zones of the northern Baltic proper. Because of successful survival and an expanding distribution range, the addition of Cercopagis to the Baltic fauna is considered to be permanent. What has previously been cited as Cercopagis pengoi encompasses the morphology of several other species, subspecies and forms. Either a number of morphologically similar species is present, or there is a number of spurious species in Cercopagis. The last hypothesis is favoured. The spatial distribution pattern of Cercopagis, as well as that of total zooplankton, was correlated with depth. Deep (〉100 m) and shallow (〈10 m) stations had significantly lower abundance than stations of intermediate depth (〈100 m). An overview of the distribution of C. pengoi group in fresh and brackish waters suggests a high tolerance to environmental factors, but with differences among taxa. Due to this ecological flexibility, the colonization of the Baltic is not unexpected. Increasing salinity may restrict dispersal of cercopagids to the southern areas of the Baltic and to the North Sea, but inland lakes (e.g. in Sweden) present an ecological profile suitable for colonization.
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  • 57
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    Hydrobiologia 431 (2000), S. 175-184 
    ISSN: 1573-5117
    Keywords: Dreissena ; lake stratification ; water clarity ; temperature ; oxygen ; metalimnion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Colonization and proliferation of zebra mussel (Dreissena polymorpha) population in Hargus lake, a small thermally stratified reservoir in Ohio, U.S.A., caused a significant increase in water clarity and a remarkable decrease in phytoplankton biomass during the period from 1993 to 1995. Increased light penetration and reduced organic matter loading to the meta-and hypolimnion were reflected in the lake stratification patterns, particularly in the temperature and oxygen profiles in the metalimnion. The meta- and hypolimnetic water temperature increased significantly over three years, irrespective of variation in surface water temperature. The epilimnion depth (mixing depth) increased by about the same magnitude as did the average Secchi depth. However, the total heat content of the lake did not show a consistent trend to increasing zebra mussel abundance, as it was largely influenced by the temperature of the large water volumes near the surface, which were in turn affected by weather conditions. Concurrent with the thermal structure change, the dissolved oxygen structure also changed over three years, though to a lesser extent. The changes in oxygen stratification pattern were reflected by increased oxygen concentrations in the metalimnion and a lowered depth of 3 mg l−1 DO isopleth. These observed changes were likely attributed to increased water mixing depth, metalimnion photosynthesis and reduced oxygen consumption by organic matter. With increased epilimnion thickness and improved oxygen conditions in the metalimnion, the habitable space for aquatic macro-organisms (including fish) expanded substantially. Our results suggest that the indirect impacts of zebra mussels on small lake stratification patterns may have much broader implications than do the direct trophic interactions to the whole ecosystem.
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  • 58
    ISSN: 1573-5117
    Keywords: nutrient flux ; nitrogen ; phosphate ; tidal flats ; temperature ; geographical comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During an annual cycle, flux rates of oxygen, nitrate, nitrite, ammonium, phosphate and silicate were measured in light and dark bell jars at three sites in Ria Formosa (Algarve, Portugal) enclosing either a natural macrophytic community (macroalgae on sand or mud, a seagrass bed of Zostera noltii) or bare sediments. The results are compared with a preceeding study in which the same bell jar technique has been applied in the Sylt-Rømø Bay of the northern Wadden Sea. Nitrate flux was mainly directed from the water column to the benthic communities in Ria Formosa, as well as in the Sylt-Rømø Bay. However, nitrate uptake was higher in the northern, more eutrophic study area. In Ria Formosa, nutrient concentrations were lower than in the Sylt-Rømø Bay possibly due to strong water exchange with Atlantic waters. High temperatures and strong insolation had a greater impact on nitrate fluxes in Ria Formosa than in the Sylt-Rømø Bay. Bioturbating macrofauna increased ammonium efflux in the Sylt- Rømø Bay while this effect was not as pronounced in the Ria Formosa study sites. Benthic phosphate uptake dominated in the Ria Formosa and was correlated to initial phosphate concentrations in incoming waters. At both study sites, oxygen and nutrient fluxes were correlated with temperature. Additionally, flux rates were strongly influenced by biotic components and levels of eutrophication. A literature survey showed that mainly in temperate regions, material fluxes increase with temperature, whereas in warmer areas, ammonium and phosphate fluxes between sediment and water were generally lower.
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  • 59
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    Biogeochemistry 48 (2000), S. 21-51 
    ISSN: 1573-515X
    Keywords: carbon cycle ; decomposition ; global change ; soil organic matter ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The world's soils contain about 1500 Gt of organic carbon to a depth of 1m and a further 900 Gt from 1--2m. A change of total soil organic carbon by just 10% would thus be equivalent to all the anthropogenic CO2 emitted over 30 years. Warming is likely to increase both the rate of decomposition and net primary production (NPP), with a fraction of NPP forming new organic carbon. Evidence from various sources can be used to assess whether NPP or the rate of decomposition has the greater temperature sensitivity, and, hence, whether warming is likely to lead to an increase or decrease in soil organic carbon. Evidence is reviewed from laboratory-based incubations, field measurements of organic carbon storage, carbon isotope ratios and soil respiration with either naturally varying temperatures or after experimentally increasing soil temperatures. Estimates of terrestrial carbon stored at the Last Glacial Maximum are also reviewed. The review concludes that the temperature dependence of organic matter decomposition can be best described as: d(T) = exp[3.36 (T − 40)/(T + 31.79)] where d(T) is the normalised decomposition rate at temperature T (in °C). In this equation, decomposition rate is normalised to ‘1’ at 40 °C. The review concludes by simulating the likely changes in soil organic carbon with warming. In summary, it appears likely that warming will have the effect of reducing soil organic carbon by stimulating decomposition rates more than NPP. However, increasing CO2 is likely to simultaneously have the effect of increasing soil organic carbon through increases in NPP. Any changes are also likely to be very slow. The net effect of changes in soil organic carbon on atmospheric CO2 loading over the next decades to centuries is, therefore, likely to be small.
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  • 60
    ISSN: 1573-5028
    Keywords: cell cycle ; kinematic analysis ; leaf development ; light ; temperature ; water deficit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In planta quantitative studies of cell cycle are necessary for examining the role of cell division in the response of plants to environmental conditions and to analyse the behaviour of transformed plants in this context. We present and discuss non-intrusive kinematic methods which allow estimating the duration of cell cycle with a high spatial resolution in the leaf. Different methods are proposed and discussed for monocotyledons and dicotyledons, and compared with methods involving the use of chemicals. In monocotyledon leaves, cell division is restricted to a limited zone near the leaf insertion point, twice as long in the mesophyll as in the epidermis. In dicotyledons, cell division occurs in the whole leaf with a uniform and constant cell cycle duration for a determinate number of cell cycles, representing about half of leaf development. Over several experiments, this number is well conserved in a given leaf zone in the absence of stresses, but larger near the leaf base than near the leaf tip. After that, cell cycle duration increases because cells are progressively blocked in G1 while the durations of S-G2-M phases do not change with time. Leaf temperature affects neither the distribution of nuclei in each phase of the cycle nor the number of cell cycles in a leaf. Water or light deficits both cause a partial blockage of nuclei in G1 during the stress only, thereby increasing cell cycle duration and decreasing final cell number. These results suggest that a strong developmental programme drives cell division in leaves, so a simple framework allows analysis of temporal patterns, of spatial gradients and of the effect of environmental conditions.
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  • 61
    ISSN: 1573-5168
    Keywords: chloride cells ; Epinephelus coioides ; grouper ; Na+,K+-ATPase activity ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity of the enzyme Na+,K+-ATPase and morphological changes of gill chloride cells in grouper, Epinephelus coioides larvae and juveniles were determined 6–48 h after abrupt transfer from ambient rearing conditions (30–32 ppt, 26.5–30 °C) to different salinity (8, 18, 32, 40 ppt) and temperature (25, 30 °C) combinations. Na+,K+-ATPase activity in day 20 larvae did not change at salinities 8–32 ppt. Activity decreased significantly (P 〈0.01) after exposure to 40 ppt at 25–30 °C, which was accompanied by an increase (P 〈0.05) in density and fractional area of chloride cells. Enzyme activity in 40 ppt did not reach a stable level and larvae failed to recover from an osmotic imbalance that produced a low survival at 25 °C and death of all larvae at 30 °C. Enzyme activity and chloride cell morphology in day 40 groupers did not change in 8–40 ppt at 25 °C and 8–32 ppt at 30 °C. A significant decrease and a subsequent increase in Na+,K+-ATPase activity in 40 ppt at 30 °C was associated with the increase in chloride cell density resulting in an increased fractional area but a decreased cell size. Enzyme activity and chloride cells of day 60 grouper were unaffected by abrupt transfer to test salinities and temperatures. These results demonstrate that grouper larvae and juveniles are efficient osmoregulators over a wide range of salinities. Salinity adaptation showed an ontogenetic shift as the larvae grew and reached the juvenile stage. This development of tolerance limits may reflect their response to actual conditions existing in the natural environment.
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  • 62
    ISSN: 1573-5168
    Keywords: Atlantic cod ; temperature ; melatonin ; photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the effects of photoperiod and temperature on plasma melatonin secretion in Atlantic cod (Gadus morhua L.). Initial work confirmed the presence of a diel profile of melatonin synthesis, with elevated levels during the dark phase. Unusually for fish, the peak in plasma melatonin occurred towards the end of the dark phase, which is indicative of a type `A' melatonin profile. When exposed to 60 hours of continuous darkness a clear endogenous rhythm of melatonin synthesis was observed, which continued for 4 cycles with a periodicity which, approximated to 24 h. When acclimated to varying temperatures (4, 8, 12 or 16 °C) no variation in melatonin production was seen, however, body size appeared to be an important influence, with the smallest fish exhibiting significantly higher levels of dark phase melatonin. Finally, the application of additional night-time illumination to cod maintained in sea cages i.e. without blackout, did not significantly reduce dark phase plasma melatonin, suggesting that cod are less sensitive to photoperiod manipulation in cages than salmonids.
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  • 63
    ISSN: 1573-5168
    Keywords: cortisol ; ACTH ; α-MSH ; GH ; head kidney ; pituitary ; temperature ; stress ; Sparus aurata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the effects of a drop in water temperature (18 °C to 9 °C in 24 h) on the pituitary and interrenal hormones of the gilthead sea bream Sparus aurata. The in vitro sensitivity of the interrenal tissue to ACTH, plasma levels of cortisol, ACTH, α-MSH, GH, glucose, lactate and ions were determined. In vitro ACTH, stimulated the release of cortisol from isolated interrenal glands from control gilthead sea bream in a concentration dependent fashion. However, the interrenal cells were less sensitive to ACTH as soon as 24 h following the onset of the temperature drop. At this time, plasma cortisol and ACTH levels were raised, and plasma GH concentrations were decreased, whereas no significant changes were found in plasma α-MSH. After 96 h plasma ACTH levels had recovered whereas plasma cortisol levels were still higher than controls after 8 days of the beginning of the experiment. Interrenal sensitivity had recovered after 8 days. The results may help to clarify the relationship between the stress response and the aetiology of the winter syndrome in sea bream.
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  • 64
    ISSN: 1573-6857
    Keywords: altitude ; clines ; latitude ; phenotypic variability ; temperature ; Zaprionus indianus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analyzed natural populations of Zaprionus indianusin 10 Indian localities along a south-north transect (latitude: 10–31°3 N). Size traits (body weight, wing length and thorax length) as well as a reproductive trait (ovariole number) followed a pattern of clinal variation, that is, trait value increased with latitude. Wing/thorax ratio, which is inversely related to wing loading, also had a positive, but non-significant correlation with latitude. By contrast, bristle numbers (sternopleural and abdominal) exhibited a non-significant but negative correlation with latitude. Sex dimorphism, estimated as the female/male ratio, was very low in Z. indianus, contrasting with results already published in other species. Genetic variations among populations were also analyzed according to other geographic parameters (altitude and longitude) and to climatic conditions from each locality. A significant effect of altitude was found for size traits. For abdominal bristles, a multiple regression technique evidenced a significant effect of both latitude and altitude, but in opposite directions. Genetic variations were also correlated to climate, and mainly with average year temperature. Taking seasonal variations into account failed however to improve the predictability of morphometrical variations. The geographic differentiation of Z.indianusfor quantitative traits suggests adaptive response to local conditions, especially to temperature, but also reveals a complex situation according to traits investigated and to environmental parameters, which does not match results on other drosophilid species.
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  • 65
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    World journal of microbiology and biotechnology 16 (2000), S. 297-301 
    ISSN: 1573-0972
    Keywords: Anaerobic bacteria ; growth ; protease ; psychrotrophs ; temperature ; volatile fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Five anaerobic proteolytic bacteria were isolated from water bodies of Leh, India, where the ambient temperature varies from −25 to 25 °C. Isolates showed growth at all temperatures ranging from 5 to 37 °C except SPL-4 and SPL-5 which showed no growth at 5 °C. The cultures could grow and produce proteases on various protein substrates and the yield varied with the substrates. Two of the cultures showed the presence of spores. Acetate was the dominant VFA during hydrolysis of protein substrates.
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  • 66
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    World journal of microbiology and biotechnology 16 (2000), S. 571-572 
    ISSN: 1573-0972
    Keywords: Anaerobes ; hydrogen sulphide ; rubber stoppers ; sulphate reduction ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Common black rubber stoppers, made from natural rubber and styrene–butadiene, may cause a loss of hydrogen sulphide from aqueous media and impede the growth of sulphate-reducing bacteria under thermophilic conditions.
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  • 67
    ISSN: 1573-0972
    Keywords: Carbondioxide ; fungi ; oxygen ; Rhizopus ; solid-substrate fermentation SSF ; tempe modelling ; temperature ; water activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rhizopus microsporus var. microsporus and var. oligosporus are used in the manufacture of various Asian fermented foods (tempe, black oncom, sufu). In view of solid-substrate fermentation (SSF) control, mycelial growth of strains of both varieties was tested for sensitivity to fluctuations of temperature, water activity and interstitial gas composition. This was achieved by measuring radial growth as well as biomass dry weight of pre-germinated microcolonies on defined media. The optimum conditions were temperature 40 °C, a w 0.995 and a gas composition of air for the growth of both strains on a model medium. Whereas radial growth rates of var. microsporus and var. oligosporus were similar, biomass growth rates of var. oligosporus were higher than those of var. microsporus under optimum conditions. The temperature-dependent growth of Rhizopus spp. at a w 〉 0.98 could be described by the Ratkowsky Equation. Carbon dioxide (5–10% v/v) inhibited the growth of Rhizopus spp. at non-limiting levels of oxygen. The two strains were able to grow at low (0.5% v/v) oxygen levels, but the mycelial density was rather low. No interrelation of water activity and gas composition was observed, but at high water activity the fungi were more sensitive to changes of temperature. The implications for process control are discussed.
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  • 68
    ISSN: 1573-0662
    Keywords: monoterpene emission ; Mediterranean pine ; seasonal variation ; light ; temperature ; algorithms ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Current inventories of terpenes released from vegetation consider only the short-term influences of light and temperature on emissions to simulate temporal variation during the year. We studied whole canopy emissions from young Pinus pinea during a 15-month enclosure in greenhouse chambers and examined data for other long-term influences. Mean daytime emission rates strongly increased during spring, reached an annual maximum of ≈ 200 pmol m−2 total needle area s−1 (1.1 μg g−1 leaf dry weight h−1) between mid June and mid August, strongly declined in fall and reached an annual minimum of ≈ 1 pmol m−2 s−1 (0.006 μg g−1 h−1) between January and February. Normalization to standard temperature and light conditions did not change the annual time course of emissions, but reduced summer to winter ratio from a factor of 200 to about 45. Seasonal variation was characterized also by changes in terpene composition: among the six main compounds, three (t-β-ocimene, linalool, 1.8-cineol) were exclusively emitted during sunlit hours in the main vegetation period, whereas the other (limonene, α-pinene, myrcene) were emitted day and night and throughout the seasons. The results suggest that different terpene sources in P. pinea foliage exist and that a great part of the annual emission course observed here results from seasonal influences on these sources. A global model to simulate plant emissions is proposed, which accounts for seasonal influences on emissions in addition to the short-term effects of temperature and light. The model is tested on field data and discussed for its general application.
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  • 69
    ISSN: 1572-9699
    Keywords: flor yeasts ; identification ; ITS ; RFLP ; ribosomal DNA ; Saccharomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The PCR amplification and subsequent restriction analysis of the region spanning the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene was applied to the identification of yeasts belonging to the genus Saccharomyces. This methodology has previously been used for the identification of some species of this genus, but in the present work, this application was extended to the identification of new accepted Saccharomyces species (S. kunashirensis, S. martiniae, S. rosinii, S. spencerorum, and S. transvaalensis), as well as to the differentiation of an interesting group of Saccharomyces cerevisiae strains, known as flor yeasts, which are responsible for ageing sherry wine. Among the species of the Saccharomyces sensu lato complex, the high diversity observed, either in the length of the amplified region (ranged between 700 and 875 bp) or in their restriction patterns allows the unequivocal identification of these species. With respect to the four sibling species of the Saccharomyces sensu stricto complex, only two of them, S. bayanus and S. pastorianus, cannot be differentiated according to their restriction patterns, which is in accordance with the hybrid origin (S. bayanus × S. cerevisiae) of S. pastorianus. The flor S. cerevisiae strains exhibited restriction patterns different from those typical of the species S. cerevisiae. These differences can easily be used to differentiate this interesting group of strains. We demonstrate that the specific patterns exhibited by flor yeasts are due to the presence of a 24-bp deletion located in the ITS1 region and that this could have originated as a consequence of a slipped-strand mispairing during replication or be due to an unequal crossing-over. A subsequent restriction analysis of this region from more than 150 flor strains indicated that this deletion is fixed in flor yeast populations.
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  • 70
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    Experimental and applied acarology 24 (2000), S. 751-774 
    ISSN: 1572-9702
    Keywords: AFLP ; allozymes ; DALP ; DNA sequencing ; genetic structure ; microsatellites ; mitochondrial DNA ; mites ; molecular systematics ; PCR ; phylogeny ; RAPD ; RFLP ; ribosomal DNA ; ticks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The application of molecular markers to the study of ticks and mites has recently yielded new insights into their population structures and taxonomic relationships. Ticks have been studied at individual, population and species level. Mites are a more diverse group and those that have been studied to the same degree as the ticks include the Tetranychidae (spider mites), Phytoseiidae (predatory mites) and the Eriophyidae. Population variation has also been studied in the important bee parasitic mite Varroa jacobsoni Oudemans. The methods used to study these organisms have much in common. At the individual level these range from general approaches, such as AFLP, RAPD or DALP, to highly specific microsatellite analysis. Although these markers also work at the population and species level, additional analysis of specific nuclear or mitochondrial genes has been conducted either by RFLP or sequencing. Molecular applications have had particular success in facilitating the identification of taxonomically difficult species, understanding population structures and elucidating phylogenetic relationships.
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  • 71
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    Experimental and applied acarology 24 (2000), S. 579-596 
    ISSN: 1572-9702
    Keywords: Tetranychus urticae ; ambulatory dispersal ; temperature ; humidity ; mortality ; emigration ; immigration ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a greenhouse and in an open field, aspects of aerial and ambulatory dispersal of the phytoseiid mite, Neoseiulus fallacis (Garman) were studied with a focus on events that would occur after aerially dispersing mites had landed on soil or associated substrates. We measured recovery of predators on lima bean plants (Phaseolus lunatus L.) that were infested with the two-spotted spider mite, Tetranychus urticae Koch. Factors thought to affect movement and colonization were distance to a receiver unit from a release (landing) point, intervening soil surfaces such as clods, gravel, fine soil and grass, and management of soil surfaces such as mulching, watering or both. In the field, the effect of distance (0.11–1.76 m) from a landing point to a receiver unit was significant, with a negative log-linear relationship. Soil surfaces such as clods and management actions such as watering with mulching allowed for more capture of predators on bean plants with prey than did other treatments. Environmental conditions greatly affected survival of N. fallacis.Predators in the field that were present on bare soil suffered high mortality (ca. 90%) at fluctuating daytime conditions of 26.4 ± 4.8°C and 56 ± 13.4% RH. Predators only suffered 10% mortality in the greenhouse under the same setting, but under more controlled and favorable environmental conditions. Effects of environmental conditions, mode of dispersal and implications to biological control are discussed.
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  • 72
    ISSN: 1573-5095
    Keywords: Coastal Plain sites ; Pinus echinata Mill. ; P. taeda L. ; precipitation ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed production was monitored during24 years using seed-collection traps inloblolly–shortleaf pine (Pinus taeda L.–P.echinata Mill.) stands located in southeast Arkansas,north-central Louisiana, and southwest Mississippi onthe southeastern Coastal Plain, USA. Sound seedproduction was correlated with mean monthlyprecipitation and temperature from National Oceanicand Atmospheric Administration weather stationslocated near the seed-collection areas to determinethe potential of weather factors in forecasting pineseed crops. Correlations were restricted to threecritical periods in the pine reproductive cycle –strobili primordia differentiation, pollination, andfertilization. The most important (P ≤ 0.05)variables correlated with pine seed production for combined locations were cumulative precipitation (r = +0.60) during July, August, and September at 27 to 25 months before seed dispersal and mean temperature (r = −0.45) in August at 26 months before seed dispersal. Because multiple environmental factors can negatively impact pine seed development during the two yearsfollowing strobili primordia differentiation,seed-production forecasts based on weather variablesshould be verified by on-site cone counts during thesummer preceding autumn seed dispersal.
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  • 73
    ISSN: 1573-5109
    Keywords: Agrostis stoloniferaL. ; cultivar identification ; RFLP ; turfgrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential use of RFLP molecular markers for the identification of four creeping bentgrass (Agrostis stolonifera L.) cultivars and one variety of A. tenuis Sibth. used as control, was investigated. Seven probes out of the total 44 screened were able to differentiate all five cultivars at once. On the basis of their genetic similarity the varieties bred at the Pennsylvania State University were grouped closely together, whereas the variety Prominent and the A. tenuis control were more distantly related.
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  • 74
    ISSN: 1573-5036
    Keywords: Acacia ; Libya ; root-nodulating bacteria ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty isolates of root-nodulating bacteria obtained from Acacia cyanophylla, A. karroo, A. cyclops, A. tortilis (subsp.raddiana), Faidherbia albida and Acacia sp., grown in different regions of Libya, were studied by performing numerical analysis of 104 characteristics. Three fast- and one slow-growing reference strains from herbaceous and woody legumes were included. Five distinct clusters were formed. The fast-growing reference strains were separated from the isolates whereas the slow-growing was included in cluster 4. With the exception of one cluster, the majority of clusters were formed regardless of the host plant or site of origin. Based on plant tests, generation times, acid production and carbon utilization the isolates were diverse (fast and slow-growing isolates). Like slow-growing isolates, most of the fast-growing isolates appeared to be non-specific, nodulated many species from the same genus notably F. albida, known to nodulate only with slow-growing strains. Most clusters grew at temperatures 35 °C and 37 °C; some grew at temperatures above 40 °C. The majority of isolates grew at acid and alkaline pH and only one isolate grew below pH 4. Most isolates were able to utilize many amino acids as nitrogen sources and to reduce nitrate. Urea was hydrolysed by all clusters. Monosaccharides and polyols were used by slow and fast-growing isolates as the only carbon sources whereas assimilation of disaccharides varied: Some isolates, like slow-growing isolates, failed to utilize these carbon sources. Most isolates were unable to utilize polysaccharides. Regarding tolerance to NaCl on agar medium, the majority of isolates were unable to grow at a concentration of 2% NaCl, but some were highly resistant and there was one isolate which grew at 8% NaCl. Most isolates were resistant to heavy metals and to antibiotics.
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  • 75
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    Plant cell, tissue and organ culture 61 (2000), S. 59-67 
    ISSN: 1573-5044
    Keywords: alar ; in vitro plantlet ; mannitol ; nitrogen ; rooting ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of leaf area of in vitro propagated potato (Solanum tuberosum L.) plantlets for further growth during acclimatisation and the after-effects of in vitro treatments on growth were examined. The in vitro treatments included different levels of alar, nitrogen or mannitol or different temperatures during the last in vitro phase, the rooting phase. Leaf area or ground cover was recorded one day after planting to soil and at the end of the first phase of ex vitro growth, the acclimatisation phase. Regression analysis showed that leaf area of a transplant at the end of acclimatisation phase was positively influenced by leaf area of the same plantlet at the beginning of the phase. The relative increase in leaf area during acclimatisation (increase/early leaf area) was linearly related to the inverse of the early leaf area, indicating almost comparable relative increases for plantlets having larger early leaf areas, but more variable responses for plantlets having smaller early leaf areas. In vitro treatments mainly affected leaf area of transplants through their effects on early leaf area. Adding alar, reducing nitrogen and reducing temperature increased leaf area. Reducing mannitol increased ground cover. A lower nitrogen concentration and higher temperature in some cultivars had slight negative effects on the relative increase in leaf area after acclimatisation. For nitrogen these negative effects were less significant than the positive effects through early leaf area. Results stress the importance of manipulation of leaf area in vitro to enhance plant performance in later stages of growth.
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  • 76
    ISSN: 1573-5060
    Keywords: Comparative genetics ; Hordeum bulbosum ; Hordeum vulgare ; mapping ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A restriction fragment length polymorphism (RFLP) based linkage map of a cross between two diploid Hordeum bulbosum (2n = 2x = 14) clones, PB1 and PB11, was constructed from 46 recombinant progeny clones. Since both parents are heterozygous, separate and combined parental maps were constructed. All of the RFLP markers screened had previously been mapped in barley (H. vulgare L.) so that comparative maps could be produced. The PB1 linkage map consists of 20 RFLP marker loci assigned to four linkage groups covering 94.3 cM. The PB11 linkage map consists of 27 RFLP marker loci assigned to six linkage groups covering 149.1 cM. Thirteen markers polymorphic in both parents were used as ‘anchors’ to create a combined linkage map consisting of 38 loci assigned to six linkage groups and covering a genetic distance of 198 cM. Marker order was highly conserved in a comparison with the linkage map of H. vulgare (Laurie etal., 1995). However, in contrast, the genetic distances for the same markers were very different being 649 cM and 198 cM respectively, a genetic distance ratio of 1: 3.3. Thus although the map was short, it can be presumed to cover half the genome of H. bulbosum. This study provides further confirmation of the close relationship between the two species and gives a basis for the development of marker mediated introgression through interspecific hybridisation between the two species.
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  • 77
    ISSN: 1573-5060
    Keywords: genetic diversity ; germplasm ; RFLP ; Triticum aestivum ; wheat breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A set of 292 accessions of common wheat (Triticum aestivum L.) representing 21 germplasm pools based on geographical or breeding program origins was assayed for RFLP diversity. Thirty cDNA and genomic DNA probes and the HindIII restriction enzyme were employed for RFLP analysis. About 61% of all 233 scored bands were present in 75% or more of the accessions. All but one of the 30 probes revealed polymorphism, and the average number of distinct patterns per probe over all accessions was 9.5.Polymorphic Information Content (PIC) values within a pool varied from 0 to 0.9 and depended on the identities of both the germplasm pool and the probe. Rare banding patterns with a relative frequency of ≤0.2 within a pool were detected. These rare patterns were more likely to occur in pools exhibiting high levels of heterogeneity. The highest level of polymorphism was observed in the Turkish landraces from Southwest Asia. The Eastern U.S. soft red winter wheat germplasm pool was more genetically diverse than the other advanced germplasm pools, and nearly as diverse as the Turkish landrace pool. RFLP-based genetic relationships between germplasm pools generally tracked expectations based on common geographical origin, breeding history and/or shared parentages. The Chinese wheat landraces from Sichuan, Tibet, and Yunnan provinces were distinct from other pools. Similarity matrices for among-pool genetic distance estimates based on either band frequencies or banding pattern frequencies showed good correlation with matrices derived from Nei and Li's mean genetic similarity estimates (r=−0.82** and r=−0.73**, respectively.
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  • 78
    ISSN: 1573-5117
    Keywords: urban runoff ; in situ bioassay ; Gammarus minus ; heavy metals ; water quality ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thompson Run, a headwater stream in central Pennsylvania (U.S.A.), supports an impaired macroinvertebrate community downstream of the outlet of a detention pond that receives urban runoff. To determine if toxicity from the metals or other pollutants in urban runoff contributed to impairment, we exposed adult, male Gammarus minus to urban runoff during a 42-day in situ bioassay that included 12 rain events. Test animals were collected from a site upstream of the detention pond outlet using two methods: precopula pair separation and sieving. Water quality, temperature and tissue metal concentrations were measured during the bioassay. The survival of precopula G. minus was lower (p=0.048) at a site downstream of the detention pond outlet compared to a site upstream of it, but the survival of sieved G. minus was not different between sites (p=0.803). Large hourly increases in temperature (up to 6.6 °C) and major reductions in water quality including order of magnitude increases in suspended materials (measured as turbidity) and the concentrations of copper, zinc and lead occurred downstream of the detention pond outlet during stormflow (i.e. following rain events). In contrast, changes in temperature and water quality were minor upstream of the pond outlet throughout the bioassay. Copper and cadmium concentrations in leaf samples and copper, zinc and lead concentrations in G. minus samples were significantly higher downstream of the pond outlet than they were upstream of it. Despite harsh conditions downstream of the pond outlet (i.e. metal contamination, inputs of suspended materials and rapid temperature increases), the in situ bioassay did not convincingly demonstrate that urban runoff was toxic to adult, male G. minus.
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  • 79
    ISSN: 1573-6857
    Keywords: genetic diversity ; Oryza ; retrotransposons ; RFLP ; wild rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To better understand the genetic diversity of the wild relatives of rice (Oryza sativa L.) in the O. officinalis species complex repetitive DNA markers were obtained from the diploid species of this complex. One cloned sequence from O. eichingeri gave intense hybridization signals with all species of the O. officinalis complex. This 242 bp clone, named pOe.49, has a copy number from 0.9 to 4.0 × 104 in diploid species of this complex. Analysis of the primary structure and database searches revealed homology of pOe.49 to a number of sequences representing part of the integrase coding domain of retroviruses and gypsy-like retrotransposons. Sequencing of specific PCR products confirmed that pOe.49 is part of a gypsy-like retrotransposon. RFLP analysis was used to study the genomic organisation of pOe.49 among 30 accessions of the O. officinalis complex using 10 restriction enzymes. Diversity analysis based on 120 polymorphic fragments obtained from the RFLP assay grouped the O. officinalis complex accessions by genome, species and eco-geographic groups. The results suggest that, with further characterization, this retrotransposon-like DNA sequence may be useful for phylogenetic analysis of species in the O. officinalis complex.
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  • 80
    ISSN: 1573-3025
    Keywords: aerobiology ; airborne pollen ; León (Spain) ; lower atmosphere ; meteorology ; mixing ratio ; relative humidity ; tethered balloon ; temperature ; wind speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was undertaken in order to understand thebehaviour of airborne pollen grains, namely therelationship between their concentrations andconcomitant meteorological parameters, at differentaltitudes (ground level, 200, 400 and 600 m) of thelower atmosphere and its daily variations over onesite (the experimental farm of the University ofLeón). The experimental design involved a tetheredballoon (2.25 m3), an ADAS remote meteorologicalstation and an original radio controlled three headedpollen and spore sampler (called GABIS) using theRotorod design. Each head sampled a differentaltitude, while two control samples were taken atground level. Twenty-one takeoffs could be realized inthe 5 weeks period between end of May and end of June1997. Sampling was done early in the morning and sampling time at each altitudewas of 15 minutes. Results show that 45 differenttypes of pollen grains could be collected at this timeof the year and that significant variations could beobserved in the behaviour of the pollen cloud on a dayto day basis, probably because of differentmeteorological situations. Contrary to what isgenerally believed, pollen was in most cases moreabundant at higher altitude – on average by 30% ascompared to ground level – making evident anaerobiological layer of transport at about 500 m aboveground. This was especially the case for trees (Quercus and Castanea). The atmosphere MixingRatio was the most explicative factor at 200 m, whiletemperature dominated significance analysis at both400 and 600 m.
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  • 81
    ISSN: 1573-2932
    Keywords: diffusion rate ; migration ; pH ; temperature ; total dissolved solids ; unplasticized PVC pipes ; vinyl chloride monomer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The migration of vinyl chloride monomer (VCM) from unplasticizedpolyvinyl chloride (uPVC) pipes was investigated using locallymanufactured pipes. Specimens of 33 cm long were used throughoutthe research. The investigation was carried out under differentconditions of water temperature, pH and total dissolved solidsconcentration and at different durations of exposure. The VCMconcentration in the water was evaluated using the gaschromotography (GC)/head-space technique. A VCM concentration ofmore than 2.5 ppb was detected after 30 days of exposure at45 °C. The initial VCM concentration in the uPVC pipewas predicted using equations derived from Fick's first law ofdiffusion. Water tenperature did not affect the migration ofVCM, unless it was raised to high values (i.e. 45 °C).Total dissolved solids (TDS) and pH of water were found toaffect the release of VCM from uPVC pipes. Diffusion rate of VCMwas predicted as a function of pH or TDS values.
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  • 82
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    Environmental monitoring and assessment 60 (2000), S. 337-357 
    ISSN: 1573-2959
    Keywords: cellulose ; charcoal kiln ; decomposition ; herb seeds ; moisture ; respiration ; smoke pollution ; soil ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Long-term charcoal production in small private charcoal kilns (CK) in Eastern Bieszczady Mts. (SE Poland) can cause local smoke contamination of the ambient forest environment. Responses of model soil systems, contaminated or not contaminated by CK smoke, to contrasting combinations of hydrothermic regimes were compared in laboratory microcosms (respiration of soil community, decomposition rate of soil organic matter and cotton stripes, herb seeds germination were studied). The majority of the obtained data show a markedly higher level of soil biological activity in the CK versus the control series. In some cases CK and control soil systems show different patterns of reactions to the tested combinations of microclimate regime. These phenomena should at least partly be attributed to the effects of CK pollution.
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  • 83
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    Environmental monitoring and assessment 61 (2000), S. 285-291 
    ISSN: 1573-2959
    Keywords: adsorption ; NO2 ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The sodium arsenite method developed by Jacobs andHochheiser is one of the most widely used manualmethods for nitrogen dioxide (NO2) monitoring inambient air, particularly in developing countries. Asreported, the method gives 82% NO2 absorptionefficiency (NAE) in the concentration range from 40 to750 μg/m3, when only one impinger tube isemployed in the sampling train at a flow rate of 0.2lpm and for 24 h sampling duration. Accordingly,a uniform correction factor (0.82) is used indenominator to calculate the ultimate concentration ofNO2 in ambient air.In the present investigation, the effect oftemperature on absorption efficiency of NO2 isstudied employing four impinger tubes in series tocollect the maximum NO2 generated in the gasstream. The study conducted at 16, 26 and 36 °Ctemperatures shows maximum absorption efficiency(average) of 87.8% at 26°C in 1st impingertube. At lower and higher temperatures, it is foundconsiderably less. A suitable correction factor,therefore, must be applied to estimate actual NO2concentration in ambient air using arsenite method, intropical countries like India, where atmospherictemperature variations are large (less than 5°Cin winter and more than 45°C in summer).
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  • 84
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    Studia geophysica et geodaetica 44 (2000), S. 442-459 
    ISSN: 1573-1626
    Keywords: temperature ; groundwater ; sedimentary basin ; exploitation ; transient effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The subsurface temperature field was studied on a set of 46 borehole logs measured in the vicinity of uranium deposits in the Bohemian Cretaceous Basin. Vertical variations of the steady state temperature and the temperature gradient are governed by thermal conductivity which strongly varies in dependence on lithology. Large departures from undisturbed temperature detected in many holes are associated with uranium mining. A positive anomaly is observed in leaching fields where large amounts of acid are injected into the uranium-bearing Cenomanian. A negative anomaly is linked to the operation of hydraulic barriers which enclose the mining area and helps to contain pollution by pumping clean water into the Cenomanian aquifer. The spatial distribution of the observed temperature anomalies helps to map the migration of the fluids used in both processes. The temperature disturbance is propagated from the Cenomanian aquifer up through overlying impermeable sediments. The good fit of transient conductive models to the measured temperatures rules out heat advection and hence upward water flow towards and contamination of the upper Middle Turonian aquifer in the vicinity of the holes studied.
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  • 85
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    Journal of human genetics 45 (2000), S. 119-126 
    ISSN: 1435-232X
    Keywords: Key words Extra-embryonic tissue ; Methylation-sensitive endonuclease ; Phosphoglycerate kinase ; RFLP ; Skewing of X-chromosome inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To investigate X-chromosome inactivation (XCI) in human trophoblasts during early pregnancy, tropho-blast genomic DNA was extracted and analyzed for a Bst XI restriction endonuclease site polymorphism in the X-linked phosphoglycerate kinase gene, after digestion with methylation-sensitive Hpa II (control samples were digested instead with Afa I). Six villous trophoblast DNA samples were informative for the polymorphism (ie, heterozygous) and were derived from women homozygous for the polymorphism. These samples were then evaluated for XCI. In five of the six samples with Hpa II predigestion, the sizes of the two heterozygous band peaks differed; maternal X-chromosome (XM)-derived alleles showed smaller peak sizes than paternal X-chromosome (XP)-derived alleles, but the differences varied in degree. In samples obtained by microdissection from formalin-fixed, paraffin-embedded tissues (30 samples from different anchoring villi, and 38 samples from different branch villi), monoclonal band patterns of XP-derived alleles were observed more frequently than those of XM-derived alleles, but almost half of the samples showed polyclonal pat-terns. Our results suggest that a skewing of XCI exists in the human trophoblast; however, the degree of non-randomness due to predominant XP inactivation appears to be restricted. It is probable that transcription of the X inactivation center (XIC) begins earlier in mice than in humans.
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  • 86
    ISSN: 1573-2932
    Keywords: microalgal communities ; photosynthesis ; temperature ; thermal pollution ; tropical coast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The influence of thermal discharges on thephytoplankton community from a coastal zone of theGulf of Mexico was evaluated through their structureand photosynthetic behaviour focusing on responses tochanges in light and temperature. Biological andphysicochemical parameters were measured over a periodof two years in an area with permanent hot waterdischarges from a thermoelectric plant. Thetemperature in the sampling area ranged from 23.5 to36 °C with differences between the coldest andthe hottest station from 5.3 to 9.2 °C.Photosynthetically active radiation (PAR) were reducedin the discharge area water column, due to turbulence.One hundred and one different taxa were identifiedwith a strong predominance of Diatoms. The chlorophylla concentration ranged from 0.3 to 6.1 μgL-1, with highest values of thephaeophytin:chlorophyll ratio found at the hottest station.The community structure did not show significativedifferences among sampling stations with respect totemperature variations. However, in the algalassemblages influenced by thermal discharges, it waspossible to observe alterations in the photosynthesisbehaviour. Phytoplankton response to short termphotosynthesis experiments was segregated according tocomposition and origin of microalgal assemblages.Samples with larger heterogeneous composition had moreconsistent oxygen production responses. Algalcommunities exposed to hot effluent showed differentdegrees of photosynthesis rate reduction,higher light requirements (〉500 μE m2 s-1)and lower temperature (25 °C) to achieve Pmaxthan algae sampled in sites without such exposure.
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  • 87
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    Water, air & soil pollution 123 (2000), S. 337-352 
    ISSN: 1573-2932
    Keywords: bleaching ; bacterial infection ; coral ; Oculina ; temperature ; toxin ; zooxanthellae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bleaching in stony-corals is the result of disruption of symbiosis between the coral hosts and photosynthetic microalgal endosymbionts (zooxanthellae). Coral bleaching events of unprecedented frequency and global extent have been reported during the last two decades. Recently, we demonstrated that bleaching of the coral Oculina patagonica in the Mediterranean Sea is caused by the bacterium Vibrio shiloi, when seawater temperature rises and allows the bacterium to become virulent. The first step in the infection process is host-specific adhesion of V. shiloi to O. patagonica via a β-galactoside receptor on the coral surface. The bacterium then penetrates into the coral tissue and produces extracellular materials which rapidly inhibit photosynthesis of zooxanthellae and bleach and lyse the algae. The inhibition of pothosynthesis is due to a low molecular weight, heat stable toxin and ammonia. Bleaching and lysis are due to a heat-labile, high molecular weight materials, probably lytic enzymes. Elevated temperature induces different virulence factors within the infectious agent of the disease, V. shiloi. Adhesion was found to be temperature-regulated. When the bacteria were grown at 16°C there was no adhesion to corals maintained at either 25°C or 16°. However, when the bacteria were grown at 25°C they adhered avidly to corals maintained at 16°C and 25°C. In addition, the production of lytic enzymes and the photosynthesis inhibitor was also found to be temperature dependent. Production of the latter toxin was ten times greater at 29°C than at 16°C, and extracellular protease was 5-fold higher in cultures grown at 29°C than at 16°C. The data presented here suggest an explanation for the correlation between elevated seawater temperatures and seasonal coral bleaching.
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  • 88
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    World journal of microbiology and biotechnology 16 (2000), S. 607-612 
    ISSN: 1573-0972
    Keywords: Aflatoxin ; apple ; fruit oils ; fungi ; patulin ; sodium hypochlorite ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Aspergillus flavus, A. niger, Penicillium expansum and Rhizopus stolonifer were the most frequently isolated fungi from healthy apple fruits. Alternaria alternata was the most common organism of rotten apple fruits, followed by A. niger, A. flavus, P. expansum and R. stolonifer. The prevalent type of decay, brown rot lesion, is caused by R. stolonifer followed by A. flavus, A. niger, A. alternata and P. expansum. Sodium hypochlorite had good curative properties against fruit rots. The main natural mycotoxins produced in rotten apple were patulin and aflatoxins. The optimum temperature for patulin production by P. expansum was 15 °C after 15 days. Complete inhibition of patulin formation was attained using 0.2% lemon oil and 〉 90% inhibition using 0.05% lemon and 0.2% orange oils. Also significant inhibition (〉 90%) of aflatoxin production was observed with 0.2% lemon oil.
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  • 89
    ISSN: 1573-2711
    Keywords: solid lubricants ; lubricious oxides ; TiO2 ; rutile ; oxygen stoichiometry ; Magnéli phases ; tribometry ; friction ; wear ; shear strength ; temperature ; atmosphere ; extreme environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In part I of this paper series, wide temperature range SEM-tribometric results generated in vacuum and various partial pressures of oxygen are combined with relevant literature data to examine a hypothesis correlating the oxygen stoichiometry of the Ti n O2n−1 Magnéli phases of the rutile polymorph of titania with their tribological behavior. Single-crystal and polycrystalline rutile specimens of narrow stoichiometry ranges were sliding against α-SiC and themselves. The surface shear strength changes were determined as a function of the thermal–atmospheric test environment, and the shear strength values were estimated by the coefficients of friction, the real area of contact and the published yield strength of rutile. The data appear to be sufficient and sufficiently reliable to confirm the accuracy of the hypothesis. The tendency of the rutile stoichiometry (ergo the friction) to shift as a function of temperature and partial pressure of oxygen causes this material to be thermo-oxidatively unstable for tribological applications in extreme environments. In part II, a study is described to formulate oxidatively more stable Magnéli phases by Cu-doping, and test the new materials by SEM tribometry using a procedure used for pure rutile here in part I. By employing this doping methodology similar to creating high-temperature superconductive oxides in part II, some feasibility of producing oxidatively stable, lubricious oxides with acceptably low wear rates is indicated.
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  • 90
    ISSN: 1573-2711
    Keywords: AFM ; force ; friction ; adhesion ; molecular water layer ; temperature ; capillary forces ; PMIRRAS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Under ambient conditions, a water film is always present on a silica substrate and generates additional capillary forces between the nanotip and the studied surface. In the present paper, we report AFM measurements of pull-off and friction forces as a function of the temperature and a comparative FTIR spectroscopy study. The AFM results show a net decrease of the forces as the temperature increases, while the IR spectroscopy indicates that the liquid film is removed at high temperature. Consequently, we deduce that a liquid neck is created between the tip and the surface and that the forces measured are mostly capillary forces. The present work shows that temperature studies with AFM can be a useful way to probe the influence of the capillary force in turn to characterize surface properties.
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  • 91
    ISSN: 1573-2711
    Keywords: solid lubricants ; lubricious oxides ; TiO2 ; rutile ; oxygen stoichiometry ; Magnéli phases ; tribometry ; friction ; wear ; shear strength ; temperature ; atmosphere ; extreme environment ; molecular engineering ; cation doping ; aliovalency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As a follow-up to the work described in part I of this paper series, a preliminary study was conducted with polycrystalline rutile TiO−x to render its friction and wear performance independent of the environment. The main goal was to confine the most tribologically desirable oxygen stoichiometries of the crystallographic shear-induced Magnéli phases (CSMP) of rutile by doping with cations similar in size and polarizability to the Ti4+, but with lower valences. The resultant chemical expulsion of oxygen from the rutile lattice was intended to generate CSMP free of friction and wear variations caused by changes in the thermal–atmospheric environment. Copper, iron, cobalt and nickel ions were tried as dopants introduced as their stable oxides via a simple ball-milling, hot-pressing and annealing procedure, but only a (Ti + Cu)O1.80 model blend resulted in a desired reaction. A portion of the copper entered the lattice to form a new titanium–copper CSMP, resembling the well-known V3Ti6O17 catalyst equivalent to an undoped rutile CSMP with an O/Ti ratio of 1.89. Although the shear behavior of this new, wear-resistant compound was in accordance with predictions, its friction is higher and more variable than desired for a wide environmental regime lubricant. The preparation technique was only sufficient to demonstrate that oxygen vacancy-induced creation of low-friction CSMP may be possible by doping; it does not appear to be useful for formulating practical, rutile-based lubricious oxides.
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  • 92
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    European journal of plant pathology 106 (2000), S. 77-85 
    ISSN: 1573-8469
    Keywords: Pestalotiopsis sydowiana ; morphology ; pathogenicity ; ericaceous plants ; conifers ; temperature ; pH ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pestalotiopsis isolates obtained from the foliage, stem-base and roots of hardy ornamentals grown on commercial nurseries in the UK were identified and characterised according to pathogenicity and colony morphology. All 18 isolates were identified as Pestalotiopsis sydowiana on the basis of conidia morphology, and confirmation of identification was made by experts at CABI Bioscience. Isolates were pathogenic on the host from which originally isolated. Typical symptoms included foliar browning of foliage and stems, and the presence of black or greenish-black acervuli on diseased tissue. Isolates were not host specific and infected other species of hardy ornamentals. Three colony types on potato dextrose agar were distinguished according to colour and production of acervuli by individual isolates. Three selected isolates of P. sydowiana were characterised by examining the effects of growth media, temperature, pH, and water potential on hyphal extension. Isolates grew well on commonly used growth media, including PDA, Sabouraud dextrose agar (SDA), V8 juice agar (V8), malt extract agar (MEA) and Czapek Dox agar (CDA). The optimum temperature for growth on PDA was in the range 20–25°C, with little or no growth occurring below 5°C or above 30°C. Hyphal extension occurred over a pH range between 2.6–8.6, with optimum values occurring at pH 5.5. In general, decreases in osmotic and matric potential caused a reduction in growth. Hyphal extension on media adjusted osmotically as NaCl ceased between −9.9 and −10.5 MPa. Isolates were more tolerant of osmotic than matric potential, with no growth occurring at −6.5 MPa on media adjusted with polyethylene glycol.
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  • 93
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    BioControl 45 (2000), S. 453-462 
    ISSN: 1573-8248
    Keywords: development ; fecundity ; functional response ; reproductive numerical response ; temperature ; Coccinellidae ; Aphis gossypii ; Scymnus levaillanti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Development and fecundity of Scymnus levaillanti(Mulsant) were recorded at fiveconstant temperatures ranging from 15 to 35 ± 1 °C in 5 °C increments, 60 ± 5% RHand 16 h of artificial light (5000 Lux). Developmentaltime (egg to adult) of S. levaillantisignificantly decreased with increasing temperatures,ranging from 63.9 days at 15 °C to 11.1 days at35 °C. Development from egg to adult required305.2 DD above a developmental threshold estimated as11.7 °C. Oviposition periods lasted 86.5, 76.1,47.2, and 31.5 days at 20, 25, 30 and 35 °C,respectively. No eggs were deposited at 15 °C.Higher temperatures resulted in shorter generationtimes (TO) and in decreased net reproductiverates (RO) of the coccinellid. S.levaillanti kept at 30 °C produced 0.151females/female/day, the highest per capita rate ofpopulation growth (rm). The `functional response'of larvae and adults of S. levaillanti matcheswell that described by Holling (1959) as Type 2.Daily number of eggs deposited by females increased toa plateau with increasing prey density. Resultsobtained here provide information about the biology ofS. levaillanti, and its feeding capacityindicates that it may act as an important control agent.
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  • 94
    ISSN: 1573-8248
    Keywords: anti-fungal substances ; control ; host plant resistance ; Megalurothrips sjostedti ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The susceptibility of Megalurothrips sjostedtito Metarhizium anisopliae when reared on susceptible, tolerant, and moderately resistant varieties of cowpea at different constant temperatures was evaluated in the laboratory. Insects were exposed either to direct spray of the conidia or to fungus-treated floral tissues. Mortality was significantly higher on the moderately resistant variety at all temperatures compared to the susceptible and tolerant varieties. Correspondingly, lethal time and lethal concentration values were significantly shorter and lower, respectively, on the moderately resistant variety compared to the other varieties, thus indicating that the two control methods are compatible as part of an integrated pest management strategy. Thrips raised on the tolerant variety incurred an exceptionally low level of mortality when the inoculum was sprayed directly on the insects or when the insects were exposed tofungus-treated floral tissues. Observations on the effects of airborne volatiles and crude extracts of this variety revealed an inhibitory effect on fungal germination, colony forming units and growth. This suggests the existence of anti-fungal substances in the tolerant variety.
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  • 95
    ISSN: 1573-8248
    Keywords: adjuvants ; attapulgite ; bentonite ; infectivity ; osmolarity ; pH ; survival ; temperature ; Heterorhabditis bacteriophora ; Heterorhabditis indica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Successful control of insect pests through theapplication of entomopathogenic nematode dauerjuveniles of H. bacteriophora and H.indica can only be achieved when the nematodematerial reaches the end user in good condition.Storage and formulation techniques must provideoptimum conditions to guarantee a maximum survival andinfectivity of the nematodes. Nematode survival wastested at temperatures ranging between 5–25 °C.A maximum survival of H. indica was achieved at15 °C and the highest mortality at 5 °C.H. bacteriophora survived best at 7.5 °Cand least at 25 °C. An increase of the saltconcentration had positive effects on dauer juvenilesurvival in aqueous suspensions. Low pH between 6 and4 reduced the bacterial growth and prolonged survivalof stored dauer juveniles. Of the organic acidsascorbic, benzoic, citric and sorbic acid, onlyascorbic acid had a positive effect on H. indicasurvival. Extracts of the dried spice plants cinnamon,cloves, rosemary and oregano were tested. Enhancementof H. indica survival was recorded for cinnamonand cloves. Survival and infectivity of nematodesstored in attapulgite and bentonite clays and spongewere recorded over several weeks at different storagetemperatures. Infectivity was not influenced by thedifferent formulation materials. When stored insponge at 25 °C nematodes survived less than 1week and the formulation in clay could only prolongthis period for another week. At 5 °C thesurvival of H. bacteriophora in sponge wassuperior to that in clay, whereas H. indicasurvived less well in sponge than in clay at15 °C. Storage in aerated water at 5 °Cfor H. bacteriophora and at 15 °C for H. indica resulted in the lowest mortality. Forstorage at controlled conditions (temperature, pH andosmolarity), aerated water is superior to all othermethods tested and the addition of preservatives willincrease survival.
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  • 96
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    Entomologia experimentalis et applicata 72 (1994), S. 273-279 
    ISSN: 1570-7458
    Keywords: oviposition ; stimulation ; narcosis ; carbon dioxide ; age ; temperature ; photoperiod ; Bombus terrestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four experiments aimed at the stimulation of starting oviposition were carried out with bumblebee queens (Bombus terrestris L.) from colonies belonging to the ecotype of Central Western France and reared in a glasshouse. After mating, queens were narcotized with carbon dioxide, confined singly in small boxes (11×5×4.5 cm) and kept in a dark room at 28–29 °C and 60%–65% r.h. They were fed on a sugar solution and a pollen-syrup mixture. No effects were discernible if the narcosis was applied 20 to 30 days after mating instead of 5 days, nor if the queens were submitted to a 4 to 5 day period at 34°C following narcosis. Survival rates ranged from 65% to 68 %. If the queens were reared under fluorescent tubes (L8∶D16) after narcosis the mean delays to egg-laying were significantly reduced compared to a dark treatment (21 days instead of 39), as was their variability (s.e.=1.6 day instead of 3.1 days). The survival rates were respectively 73% and 67%. Under the same photoperiod (L8∶D16) the CO2 narcosis repeated at a 24h interval had the same efficacy whether its duration was 10 min or 5 min. The delays to egg-laying were respectively 20 days (s.e=1.5) and 25 days (s.e.=4.8) with survival rates close to 73%. Egg-laying could also be induced in non-narcotized queens with a survival rate of 54% and delays to oviposition close to those of queens narcotized 2×10 min.
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  • 97
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    Entomologia experimentalis et applicata 73 (1994), S. 221-229 
    ISSN: 1570-7458
    Keywords: Agaonidae ; host choice ; dispersal ; Ficus ; migration ; Moraceae ; take off ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ficus burtt-davyi, like most other fig species (Ficus, Moraceae), is exclusively pollinated by its own unique species of fig wasp, in this caseElisabethiella baijnathi (Chalcidoidea, Agaonidae). Because fig crop development on any one tree is usually synchronised, the small and short-lived female wasps have to migrate and find other trees bearing figs which are at suitable stage of development for oviposition. However, the likelihood of successful location and subsequent arrival at a new host tree is dependent on distance and the effect of environmental factors such as wind and temperature. This study examines the relationship between ambient temperatures and the timing of fig wasps emergence from their natal figs and the commencement of their dispersal flight. The behaviour of the wasps arriving at figs which were ready to be pollinated was also examined. The female wasps did not appear to distinguish between the figs and other parts of the tree when in flight. However, after landing on the tree their search for figs was more directed as they visited more figs than leaves. Short-range recognition of figs appears to be by contact chemo-reception, but the wasps showed a preference for entering figs which did not already contain a female wasp.
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  • 98
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    Entomologia experimentalis et applicata 72 (1994), S. 25-31 
    ISSN: 1570-7458
    Keywords: diapause induction ; photoperiod ; temperature ; Phyllonorycter blancardella ; spotted tentiform leafminer ; Lepidoptera ; Gracillariidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of photoperiod and temperature in the induction of overwintering diapause inPhyllonorycter blancardella (F.) (Lepidoptera: Gracillariidae) was examined in the laboratory and field using leafminers from commercial apple orchards in Ontario, Canada.P. blancardella exhibited a long-day response to photoperiod: long daylengths resulted in uninterrupted development whereas short daylengths induced diapause. The estimated critical photoperiod for diapause induction was L14.25∶D9.75. The larvae of leafminers destined to enter diapause took ca. 3× longer to complete development than the larvae of non-diapausing leafminers. The development prolonging effect of photoperiod decreased with decreasing daylength. Temperature modified the diapause inducing effect of photoperiod. At L14.25∶D9.75, diapause incidence was similar at 15 and 20°C but was lower at 25°C. Photoperiod also altered the normal relationship between development rate and temperature. At L14.25∶D9.75, the duration of larval development of diapausing leafminers was similar at 15, 20 and 25°C. Temperature alone is unlikely to have a role in the induction of diapause because leafminers exposed to natural late summer and fall temperature regimes and L16∶D8 did not enter diapause.
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  • 99
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    Entomologia experimentalis et applicata 72 (1994), S. 125-133 
    ISSN: 1570-7458
    Keywords: growth rate ; consumption rate ; molt ; nutritional ecology ; rutin ; temperature ; thermocycles ; tobacco hornworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of different concentrations of rutin and constant temperature (20 °C) versus alternating temperatures (23∶15 °C) on growth, molting and food utilization efficiencies of third instar tobacco hornworms (Manduca sexta) were determined. Relative consumption rate (RCR) and relative growth rate (RGR) were significantly higher for larvae at the alternating thermal regime compared to those at the constant (representing the average) temperature. With increasing concentrations of rutin, the negative effect of rutin on RCR and RGR increased for the larvae in the alternating thermal regime; however, at the constant temperature, rutin had little effect. The alternating thermal regime promoted synchrony in the timing of spiracle apolysis (the earliest morphological marker of molt). Rutin disrupted that synchrony. I discuss how patterns of host plant resistance may be altered with a decrease, in amplitude of diurnal temperatures (as has been documented recently for temperate regions) through the uncoupling of herbivore performance and allelochemical concentration. I conclude that simultaneous consideration of fluctuating temperatures and allelochemicals is advisable when assessing the effects of temperature and allelochemicals on performance of insect herbivores because interactive effects between temperature and dietary components occur and perhaps are common.
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  • 100
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    Entomologia experimentalis et applicata 73 (1994), S. 127-137 
    ISSN: 1570-7458
    Keywords: Heteroptera ; Anthocoridae ; Orius insidiosus ; Orius tristicolor ; Orius majusculus ; Orius albidipennis ; diapause induction ; termination ; photoperiod ; temperature ; sensitive stages ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoperiodic induction of reproductive diapause at 18°C was investigated in fourOrius [Heteroptera: Anthocoridae] species.Orius insidiosus (Say) displayed a long-day response with a critical photoperiod between L11:D13 and L12:D12. Diapause in this species was terminated rapidly when the temperature and/or the daylength were increased.Orius majusculus (Reuter) also displayed a long-day response. The critical photoperiod fell between L14:D10 and L16:D8. Diapause in this species was not terminated within 14 days when both temperature and daylength were increased. InOrius albidipennis (Reuter) no diapause could be induced at photoperiods varying from L8:D16 to L16:D8. InOrius tristicolor (White) a high proportion of diapause was found at all photoperiods tested. The effect of temperature on photoperiodic induction of diapause was studied inO. insidiosus at L10:D14. Diapause occurred at 18°C, 21°C and 25°C, but not at 30°C. Again, diapause was terminated rapidly after transfer to 25°C/L16:D8. Exposing only the nymphal instars 1–5 to short daylength was not enough to induce diapause in the whole population ofO. majusculus. Orius predatory bugs are used as biocontrol agents against western flower thrips,Frankliniella occidentalis (Pergande) [Thysanoptera: Thripidael, in greenhouses. The consequences of photoperiodic induction of diapause for the success of early season releases ofOrius are discussed.
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