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991.
The intentional introduction of red king crab, Paralithodes camtschatica (Tilesius, 1815) in the Barents Sea represent one of a few successful cases and one that now supports a commercial fishery.
Introductions of alien species into new environments are often associated with genetic bottlenecks, which cause a reduction
in the genetic variation, and this could be important for the spreading potential of the species in the Atlantic Ocean. Red
king crab samples collected in the Varangerfjord located on the Barents Sea (northern Norway) were compared with reference
crab samples collected from the Bering Sea and Kamchatka regions in the Pacific Ocean. All samples were screened for eleven
microsatellite loci, based on the development of species-specific primers. The observed number of alleles per locus was similar,
and no reduction in genetic variation, including gene diversity and allelic richness, was detected between the Varangerfjord
sample and the reference sample from Okhotsk Sea near Kamchatka, indicating no genetic bottlenecking at least for the microsatellite
loci investigated. The same results were found in comparison with the sample from Bering Sea. The level of genetic differentiation
among the samples, measured as overall F
ST
across all loci, was relatively low (0.0238) with a range of 0.0035–0.1000 for the various loci investigated. The largest
pairwise F
ST
values were found between the Bering Sea and Varangerfjord/Barents Sea samples, with a value of 0.0194 across all loci tested.
The lowest value (0.0101) was found between the Varangerfjord and Kamchatka samples. Genetic differentiation based on exact
tests on allele frequencies revealed highly significant differences between all pairwise comparisons. The high level of genetic
variation found in the Varangerfjord/Barents Sea sample could be of significance with respect to further spreading of the
species to other regions in the North Atlantic Ocean. 相似文献
992.
Knut E. Jørstad P. A. Prodohl A.-L. Agnalt M. Hughes E. Farestveit A. F. Ferguson 《Hydrobiologia》2007,590(1):103-114
American lobsters (Homarus americanus H. Milne Edwards, 1837) are imported live to Europe and should according regulations be kept in land-based tanks until sold. In spite of the strict regulations aimed specifically at preventing the introduction of this species into the NE Atlantic, several specimens of H. americanus have been captured in the wild, especially in Oslofjord, Norway since 1999. One of the great concerns is interbreeding between the introduced American species and the local European lobster, H. gammarus (Linnaeus, 1758). For this reason an awareness campaign was launched in 2000 focusing on morphologically “unusual” lobsters caught in local waters. Morphological characters have been based on colour and sub-ventral spines on the rostrum. Two samples of H. americanus were used for comparisons, as well as samples of European lobster from Oslofjord collected in 1992. Previous genetic analyses (allozymes, mtDNA and microsatellite DNA) have demonstrated that the American lobster is distinct from its European counterpart, with several additional alleles at many loci in addition to different allelic frequency distribution of alleles of “shared” alleles. During the present study, thirteen microsatellite loci were tested in the initial screening, and the three most discriminating loci (Hgam98, Hgam197b and Hgam47b) were used in a detailed comparison between the two species. A total of 45 unusual lobsters were reported captured from Ålesund (west) to Oslofjord (southeast) from 2001 to 2005 and these were analysed for the three microsatellite loci. Nine specimens were identified as American lobsters. Comparisons between morphological and genetic characteristics revealed that morphological differences are not reliable in discrimination the two species, or to identify hybrids. Further, some loci display almost no overlapping in allele frequency distribution for the reference samples analysed, thus providing a reliable tool to identify hybrids. 相似文献
993.
Enrique Arbeláez-Cortes María Fernanda Castillo-Cárdenas Nelson Toro-Perea Heiber Cárdenas-Henao 《Hydrobiologia》2007,583(1):321-330
Rhizophora mangle, one of the five species of the genus Rhizophora, is found widely distributed along the American and West African coasts. This species is one of the principal constituents
of the mangrove ecosystem in Colombia and is also found within the most important economic activities for the communities
that inhabit the littoral. In order to assess the degree of genetic diversity of R. mangle in five populations of the Colombian Pacific, nuclear microsatellite molecular markers were used. In 92 individuals sampled,
it was found that 100% of the loci were polymorphic
, and no private alleles were detected. The population structure of R. mangle in the Colombian Pacific, was highly significant (P < 0.001); however, the greatest differentiation was detected at the within-population level (94.62%). For the populations
of La Plata, Virudó and Charambirá, the tendency toward panmixia could be the cause of the low differentiation among these
three locations. Within populations, the genetic diversity revealed a deviation from Hardy–Weinberg equilibrium with high
significance in Virudó and Tumaco, where it appears the intense anthropogenic activity has exercised strong pressure on the
red mangrove, resulting in the possible fragmentation of the local landscape and therefore an increase in the rate of endogamy
within these populations. Despite this situation, our study―one of the first developed in genetics of the red mangrove in
Colombia―did not show evidence of recent bottleneck effects or deterioration in its genetic composition, which could be exploited
to propose management and restoration programs for the zones where the forests of this species are degraded.
Handling editor: K. Martens 相似文献
994.
Gernot Segelbacher Per Wegge Andrey V. Sivkov Jacob H?glund 《Journal of Ornithology》2007,148(1):79-84
We quantified the genetic structure among 58 capercaillie (Tetrao urogallus) from three closely spaced leks in boreal Russia using ten microsatellite loci. We did not find significant structuring with
respect to lek membership in an overall analysis. However, all but one individual could be strongly assigned to one of two
genetic clusters, which we interpret as reflecting different local lineages or extended family groups. There was evidence
for structuring among some clusters within leks, and one smaller lek consisted of nine out of ten males from one cluster,
which could reflect kin biasing of lek membership. One cluster was apparently outperforming the other, since nine out of ten
juveniles sampled belonged to it. 相似文献
995.
Jakob Augustin Donald Blomqvist Tibor Szép Zoltán D. Szabó Richard H. Wagner 《Journal of Ornithology》2007,148(2):189-198
Genetic parentage studies of socially monogamous birds reveal a widespread prevalence of extra-pair paternity. Variation in
extra-pair paternity among individuals may depend on how different individuals benefit from extra-pair fertilisations and
on the opportunity to pursue extra-pair copulations. A long-term study of sand martins (Riparia riparia) in Hungary allowed us to examine patterns of extra-pair fertilisations in a large colony of over 3,000 breeding pairs with
many known age individuals. We used multi-locus DNA fingerprinting to determine whether extra-pair fertilisations occur when
females are paired to (1) presumably low quality mates, or (2) genetically similar or dissimilar mates, and whether extra-pair
fertilisations result in offspring of higher quality. Extra-paternal young were found in 38% of 47 broods and comprised 19%
of 190 offspring. Males that lost paternity did not differ significantly from others in age or body condition. Social mates
of broods containing extra-pair offspring did not differ in genetic similarity from pairs without extra-pair offspring. Furthermore,
there was no significant difference in body condition between extra-pair young and their maternal half-siblings. We were unable
to assign paternity and therefore cannot exclude the possibility that extra-pair males differed from the within-pair males
they cuckolded, in age, body condition or genetic similarity with the female. We found a positive relationship between paternity
losses and breeding density, suggesting that low breeding density may constrain opportunities for seeking extra-pair copulations. 相似文献
996.
Vagenas D Doeschl-Wilson A Bishop SC Kyriazakis I 《International journal for parasitology》2007,37(14):1617-1630
An in silico mathematical model was used to explore the effect of, and the interaction between, (i) nutrition, (ii) genotype for growth and (iii) genotype for resistance, on the estimates of genetic parameters for resistance and performance in a population of lambs trickle-challenged daily with 3,000 L3s of Teladorsagia circumcincta. A previously published model for nematode infections in sheep was developed to include heritable variation in sheep growth traits, as well as in immunologically controlled traits such as establishment of incoming larvae, mortality of the adult worms and fecundity of the adult female worms. The simulated population comprised 10,000 lambs, these being the offspring of 250 sires mated to 5,000 dams. The model assumed the lambs to be parasitologically naïve at weaning (2 months of age), at which point the trickle challenge commenced and the model was updated daily until slaughter (at 6 months of age). Dietary treatments included a good and a poor quality feed, offered ad libitum. Two genotypes for growth were assumed: (i) fast and (ii) slow growing. Three genotypes for resistance were used: (i) benchmark, (ii) susceptible and (iii) resistant, differing in their ability to cope with nematode infections. Genetic parameters for output traits, including growth rate, food intake, worm burden and faecal egg count were estimated using a linear mixed model, fitting sire as a random effect to capture genetic effects. Heritabilities and correlations were found to change over time. In general, the heritabilities of immunity traits increased over time, whereas genetic correlations between production and immunity traits became weaker. Diet had a significant effect on the means and the estimated correlations of output traits, while genotypes for growth and resistance had smaller effects. These results suggest that discrepancies between published genetic parameters for nematode resistance may be a function of environmental factors rather than differences in host genotype. 相似文献
997.
Zhang X Mahmudi-Azer S Connett JE Anthonisen NR He JQ Paré PD Sandford AJ 《Human genetics》2007,120(5):681-690
Polymorphonuclear leukocytes (PMNs) are major effector cells in the chronic airway inflammation in chronic obstructive pulmonary
disease (COPD). PMN degranulation is associated with degradation of extracellular matrix and tissue damage. Hck is an essential
molecule in the signaling pathway regulating PMN degranulation. We hypothesized that polymorphisms affect the expression level
of Hck, which, in turn, modulates PMN mediator release and tissue damage and influences the development of COPD. Here we systematically
investigated genetic tag polymorphisms of the Hck gene, Hck mRNA and protein expression pattern in PMNs, and PMN mediator release (myeloperoxidase) in 60 healthy white subjects, and
assessed their association with the use of several genetic models. The association of genetic polymorphisms with COPD-related
phenotypes was determined in the lung healthy study cohort (LHS). We identified a novel 15 bp insertion/deletion polymorphism
(8,656 L/S) in intron 1 of the Hck gene, which was associated with differential expression of Hck protein and PMN myeloperoxidase release. In the LHS cohort,
there was significant interaction between the 8,656 L/S polymorphism and smoking on baseline lung function and 8,656 L/S was
associated with bronchodilator response. These data suggest that the insertion/deletion polymorphism could be a functional
polymorphism of the Hck gene, may contribute to COPD pathogenesis and modify COPD-related phenotypes. 相似文献
998.
大豆异黄酮代谢途径在大肠杆菌中的构建及表达 总被引:1,自引:0,他引:1
自然界异黄酮合成途径主要存在于豆科植物中。以微生物为宿主研究异黄酮代谢,则需要将整个相关代谢途径的多酶体系组装到工程菌种,从而进行表达及代谢研究,这就需要用到多基因的转化和共表达技术。综合应用了多基因单载体和多基因多载体方法,将大豆异黄酮代谢途径中的五个关键酶基因导入到大肠杆菌中,对异黄酮代谢途径在大肠杆菌中的构建和表达进行了研究和探索,获得了含有五个外源基因的重组大肠杆菌;重组菌经IPTG诱导,以L-酪氨酸为底物进行发酵,发酵产物经过HPLC测定,结果表明和空白对照相比有新的代谢产物生成,初步断定为异黄酮类化合物。 相似文献
999.
1000.