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1.
H. A. Bell R. E. Down E. C. Fitches J. P. Edwards A. M. R. Gatehouse 《Biocontrol Science and Technology》2003,13(8):729-741
The effects of the transgene proteins Galanthus nivalis agglutinin (GNA) and cowpea trypsin inhibitor (CpTI) on the predatory stinkbug Podisus maculiventris were studied under laboratory conditions. When the P. maculiventris were provided with tomato moth (L. oleracea) larvae injected with either GNA or CpTI at a dose of 10 μg day-1, growth was significantly reduced and, as a consequence, female adult weight was also significantly reduced. For GNA-fed and CpTI-fed P. maculiventris, this weight reduction was 11.3 and 16.6%, respectively. Males, however, were not significantly affected. Female bugs that had not been exposed to the transgene proteins as nymphs, however, showed no reduction in fecundity when these adults were provided with prey injected with either GNA or CpTI at this same dose. When provided with hosts that had been reared on transgenic plants expressing either GNA or CpTI, no effects on the survival of nymphs were observed and only small, largely non-significant, reductions in weights were recorded throughout preadult development. Male nymphs fed on the GNA-fed prey did, however, exhibit a significant lengthening of preadult development of 0.8 days. The subsequent adults showed significantly reduced egg production for the GNA treatment. The results indicate that P. maculiventris may suffer some indirect adverse effects from foraging for prey in crops expressing either GNA or CpTI, due to prey being of inferior quality, rather than to direct toxicity of the transgene products themselves. 相似文献
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Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
相似文献
4.
Down RE Ford L Woodhouse SD Raemaekers RJ Leitch B Gatehouse JA Gatehouse AM 《Journal of insect physiology》2000,46(4):379-391
Two-spot ladybird (Adalia bipunctata L.) larvae were fed on aphids (Myzus persicae (Sulz.)) which had been loaded with snowdrop lectin (Galanthus nivalis agglutinin; GNA) by feeding on artificial diet containing the protein. Treatment with GNA significantly decreased the growth of aphids. No acute toxicity of GNA-containing aphids towards the ladybird larvae was observed, although there were small effects on development. When fed a fixed number of aphids, larvae exposed to GNA spent longer in the 4th instar, taking 6 extra days to reach pupation; however, retardation of development was not observed in ladybird larvae fed equal weights of aphids. Ladybird larvae fed GNA-containing aphids were found to be 8-15% smaller than controls, but ate a significantly greater number of aphids (approx. 40% to pupation). GNA was shown to be present on the microvilli of the midgut brush border membrane and within gut epithelial cells in ladybird larvae fed on GNA-dosed aphids, although disruption of the brush border was not observed. It is hypothesised that GNA does not have significant direct toxic or adverse effects on developing ladybird larvae, but that the effects observed may be due to the fact that the aphids fed on GNA are compromised and are thus a suboptimal food. 相似文献
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Costello AB Down TE Pollard SM Pacas CJ Taylor EB 《Evolution; international journal of organic evolution》2003,57(2):328-344
An understanding of the relative roles of historical and contemporary factors in structuring genetic variation is a fundamental, but understudied aspect of geographic variation. We examined geographic variation in microsatellite DNA allele frequencies in bull trout (Salvelinus confluentus, Salmonidae) to test hypotheses concerning the relative roles of postglacial dispersal (historical) and current landscape features (contemporary) in structuring genetic variability and population differentiation. Bull trout exhibit relatively low intrapopulation microsatellite variation (average of 1.9 alleles per locus, average He = 0.24), but high levels of interpopulation divergence (F(ST) = 0.39). We found evidence of historical influences on microsatellite variation in the form of a decrease in the number of alleles and heterozygosities in populations on the periphery of the range relative to populations closer to putative glacial refugia. In addition, one region of British Columbia that was colonized later during deglaciation and by more indirect watershed connections showed less developed and more variable patterns of isolation by distance than a similar region colonized earlier and more directly from refugia. Current spatial and drainage interconnectedness among sites and the presence of migration barriers (falls and cascades) within individual streams were found to be important contemporary factors influencing historical patterns of genetic variability and interpopulation divergence. Our work illustrates the limited utility of equilibrium models to delineate population structure and patterns of genetic diversity in recently founded populations or those inhabiting highly heterogeneous environments, and it highlights the need for approaches incorporating a landscape context for population divergence. Substantial microsatellite DNA divergence among bull trout populations may also signal divergence in traits important to population persistence in specific environments. 相似文献
7.
M Alonso N Alonso Rodriguez C Garzelli M Martínez Lirola M Herranz S Samper MJ Ruiz Serrano E Bouza D García de Viedma 《BMC microbiology》2010,10(1):151
Background
The Beijing lineage of Mycobacterium tuberculosis is causing concern due to its global distribution and its involvement in severe outbreaks. Studies focused on this lineage are mainly restricted to geographical settings where its prevalence is high, whereas those in other areas are scarce. In this study, we analyze Beijing isolates in the Mediterranean area, where this lineage is not prevalent and is mainly associated with immigrant cases. 相似文献8.
Schistosomiasis vector snails are subjected to extreme seasonal changes, particularly in ephemeral rivers and lentic waterbodies. In the tropics, aestivation is one of the adaptive strategies for survival and is used by snails in times of extremely high temperatures and desiccation. Aestivation therefore plays an important role in maintaining the transmission of schistosomiasis. This review assesses the possible impacts of climate change on the temporal and spatial distribution of schistosomiasis-transmitting snails with special emphasis on aestivation, and discusses the effect of schistosome infection on aestivation ability. The impacts of parasite development on snails, as well as physiological changes, are discussed with reference to schistosomiasis transmission. This review shows that schistosome-infected snails have lower survival rates during aestivation, and that those that survive manage to get rid of the infection. In general, snail aestivation ability is poor and survival chances diminish with time. Longer dry periods result in fewer, as well as uninfected, snails. However, the ability of the surviving snails to repopulate the habitats is high. 相似文献
9.
Jason A Roberts Michael S Roberts Andrew Semark Andrew A Udy Carl MJ Kirkpatrick David L Paterson Matthew J Roberts Peter Kruger Jeffrey Lipman 《BMC anesthesiology》2011,11(1):1-7