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排序方式: 共有109条查询结果,搜索用时 15 毫秒
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White Nicholas J Ashley Elizabeth A Recht Judith Delves Michael J Ruecker Andrea Smithuis Frank M Eziefula Alice C Bousema Teun Drakeley Chris Chotivanich Kesinee Imwong Mallika Pukrittayakamee Sasithon Prachumsri Jetsumon Chu Cindy Andolina Chiara Bancone Germana Hien Tran T Mayxay Mayfong Taylor Walter RJ von Seidlein Lorenz Price Ric N Barnes Karen I Djimdé Abdoulaye ter Kuile Feiko Gosling Roly Chen Ingrid Dhorda Mehul J Stepniewska Kasia Guérin Philippe Woodrow Charles J Dondorp Arjen M Day Nicholas PJ Nosten Francois H 《Malaria journal》2014,13(1):1-14
Background
Effective mating between laboratory-reared males and wild females is paramount to the success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically modified male mosquitoes. However mosquito colonization and laboratory maintenance have the potential to negatively affect male genotypic and phenotypic quality through inbreeding and selection, which in turn can decrease male mating competitiveness in the field. To date, very little is known about the impact of those evolutionary forces on the reproductive biology of mosquito colonies and how they ultimately affect male reproductive fitness.Methods
Here several male reproductive physiological traits likely to be affected by inbreeding and selection following colonization and laboratory rearing were examined. Sperm length, and accessory gland and testes size were compared in male progeny from field-collected females and laboratory strains of Anopheles gambiae sensu stricto colonized from one to over 25 years ago. These traits were also compared in the parental and sequentially derived, genetically modified strains produced using a two-phase genetic transformation system. Finally, genetic crosses were performed between strains in order to distinguish the effects of inbreeding and selection on reproductive traits.Results
Sperm length was found to steadily decrease with the age of mosquito colonies but was recovered in refreshed strains and crosses between inbred strains therefore incriminating inbreeding costs. In contrast, testes size progressively increased with colony age, whilst accessory gland size quickly decreased in males from colonies of all ages. The lack of heterosis in response to crossing and strain refreshing in the latter two reproductive traits suggests selection for insectary conditions.Conclusions
These results show that inbreeding and selection differentially affect reproductive traits in laboratory strains overtime and that heterotic ‘supermales’ could be used to rescue some male reproductive characteristics. Further experiments are needed to establish the exact relationship between sperm length, accessory gland and testes size, and male reproductive success in the laboratory and field settings. 相似文献25.
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P. Kása RW. Dames† Z. Rakonczay K. Gulya F. Joó‡ RJ. R. Wolff† 《Journal of neurochemistry》1985,44(5):1363-1372
gamma-Aminobutyric acid (GABA) was applied to the superior cervical ganglion (SCG) of CFY rats in vitro and in vivo, with or without implantation of a hypoglossal nerve, to evaluate the effects of these experimental interventions on the acetylcholine (ACh) system, which mainly serves the synaptic transmission of the preganglionic input. Long-lasting GABA microinfusion into the SCG in vivo apparently resulted in a "functional denervation." This treatment reduced the acetylcholinesterase (AChE; EC 3.1.1.7) activity by 30% (p less than 0.01) and transiently increased the number of nicotinic acetylcholine receptors, but had no significant effect on the choline acetyltransferase (acetyl-coenzyme A:choline-O-acetyltransferase; EC 2.3.1.6) activity, the ACh level, or the number of muscarinic acetylcholine receptors. The relative amounts of the different molecular forms of AChE did not change under these conditions. In vivo GABA application to the SCG with a hypoglossal nerve implanted in the presence of intact preganglionic afferent synapses exerted a significant modulatory effect on the AChE activity and its molecular forms. The "hyperinnervation" of the ganglia led to increases in the AChE activity (to 142.5%, p less than 0.01) and the 16S molecular form (to 200%, p less than 0.01). It is concluded that in vivo GABA microinfusion and GABA treatment in the presence of additional cholinergic synapses has a modulatory effect on the elements of the ACh system in the SCG of CFY rats. 相似文献
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Rocjard R. Kirby RJ. Berry D.A. Powers 《Biological journal of the Linnean Society. Linnean Society of London》1997,62(2):299-312
Genetic constitution in the intertidal gastropod Nucella lapillus (L.) influences shell shape, growth rate and physiology. Clinal variation in these traits along a 5 km stretch of coastline in south Devon can be related to environmental variation in temperature and desiccation stress. We have examined mtDNA variation along this shore to investigate whether the cline represents primary or secondary contact. Two distinct mtDNA haplotypes were found which exhibit coincident step clines with karyotypic, allozymic and phenotypic variation and covary with the environmental pressures of temperature and desiccation. These results are interpreted in the context of the wider scale distribution of genetic and phenotypic variation in N. lapillus. It is suggested that the shore studied may represent one of a number of regions of secondary contact within a mosaic hybrid zone in N. lapillus , where coadapted phenotypic variation correlates with habitat and the position of the clines represents an environmental transition. 相似文献
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The teleost Fundulus heteroclitus (L.) possesses two loci, Gpi-A and Gpi-B,
for the glycolytic enzyme, glucose-phosphate isomerase (GPI; D-
glucose-6-phosphate ketol-isomerase; E.C. 5.3.1.9). The Gpi-B locus is
polymorphic in Fundulus, with two common alleles, Gpi-Bb and Gpi-Bc,
distributed in a clinal manner in populations along the east coast of North
America. Since this clinal distribution is strongly correlated with a
temperature gradient, we asked whether the GPI-B2 allozymes were
functionally adapted to the thermal environment in which a given phenotype
predominated. The two major GPI-B2 allozymes were purified to homogeneity
and were characterized as to molecular weight, isoelectric pH, thermal
denaturation, and kinetic parameters. Both GPI-Bb2 and GPI- Bc2 allozymes
have molecular masses of 110 kD, and they have isoelectric pHs of 6.4 and
6.6, respectively. The GPI-Bb2 allozyme was more stable to thermal
denaturation than was the GPI-Bc2 enzyme. Kinetic properties of the allelic
isozymes were investigated both as a function of pH and as a function of
temperature. At 25 degrees C, over the pH range considered, there were no
significant differences between allozymes, either in Km for
fructose-6-phosphate or in Ki for 6- phosphogluconate, but apparent Vmax
values differed between pH 7.5 and pH 8.5. All steady-state kinetic
parameters showed strong temperature dependence, but the allozymes differed
only in the Ki for 6- phosphogluconate at temperatures greater than 30
degrees C. On the basis of the observed structural and functional
differences alluded to above, the hypothesis that the major allelic
isozymes of the Gpi-B locus were functionally equivalent was rejected.
However, it is not yet known whether these structural and functional
differences have any significance at higher levels of biological
organization.
相似文献
30.
Bdellovibrio sp. strain W bdellocysts were produced inEscherichia coli using three sources of3H-diaminopimelic acid (DAP) for incorporation into the cyst wall peptidoglycan: (a) labeledE. coli peptidoglycan, (b) labeledBdellovibrio peptidoglycan, and (c) exogenous3H-DAP in the encystment medium. After cysts were produced, they were either sonicated to remove the prey cell wall, or germinated to solubilize the cyst wall. The results show that label was incorporated into the cyst wall preferentially from the exogenous DAP in the medium, and not from the bdellovibrio or bdelloplast peptidoglycan. The encysting bdellovibrio does not therefore incorporate existing peptidoglycan units from the bdelloplast for synthesis of the cyst wall. 相似文献