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排序方式: 共有199条查询结果,搜索用时 15 毫秒
1.
2.
Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves 总被引:4,自引:0,他引:4
A puzzling population-genetic phenomenon widely reported in allozyme
surveys of marine bivalves is the occurrence of heterozygote deficits
relative to Hardy-Weinberg expectations. Possible explanations for this
pattern are categorized with respect to whether the effects should be
confined to protein-level assays or are genomically pervasive and expected
to be registered in both protein- and DNA-level assays. Anonymous nuclear
DNA markers from the American oyster were employed to reexamine the
phenomenon. In assays based on the polymerase chain reaction (PCR), two
DNA-level processes were encountered that can lead to artifactual genotypic
scorings: (a) differential amplification of alleles at a target locus and
(b) amplification from multiple paralogous loci. We describe symptoms of
these complications and prescribe methods that should generally help to
ameliorate them. When artifactual scorings at two anonymous DNA loci in the
American oyster were corrected, Hardy-Weinberg deviations registered in
preliminary population assays decreased to nonsignificant values.
Implications of these findings for the heterozygote-deficit phenomenon in
marine bivalves, and for the general development and use of PCR-based
assays, are discussed.
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3.
Basolateral plasma membrane localization of ouabain-sensitive sodium transport sites in the secretory epithelium of the avian salt gland
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The distribution of Na+ pump sites (Na+-K+-ATPase) in the secretory epithelium of the avian salt gland was demonstrated by freeze-dry autoradiographic analysis of [(3)H] ouabain binding sites. Kinetic studies indicated that near saturation of tissue binding sites occurred when slices of salt glands from salt-stressed ducks were exposed to 2.2 μM ouabain (containing 5 μCi/ml [(3)H]ouabain) for 90 min. Washing with label-free Ringer's solution for 90 min extracted only 10% of the inhibitor, an amount which corresponded to ouabain present in the tissue spaces labeled by [(14)C]insulin. Increasing the KCl concentration of the incubation medium reduced the rate of ouabain binding but not the maximal amount bound. In contrast to the low level of ouabain binding to salt glands of ducks maintained on a freshwater regimen, exposure to a salt water diet led to a more than threefold increase in binding within 9-11 days. This increase paralleled the similar increment in Na+-K+-ATPase activity described previously. [(3)H]ouabain binding sites were localized autoradiographically to the folded basolateral plasma membrane of the principal secretory cells. The luminal surfaces of these cells were unlabeled. Mitotically active peripheral cells were also unlabeled. The cell-specific pattern of [(3)H]ouabain binding to principal secretory cells and the membrane-specific localization of binding sites to the nonluminal surfaces of these cells were identical to the distribution of Na+-K+-ATPase as reflected by the cytochemical localization of ouabain-sensitive and K+-dependent nitrophenyl phosphatase activity. The relationship between the nonluminal localization of Na+-K+-ATPase and the possible role of the enzyme n NaCl secretion is considered in the light of physiological data on electrolyte transport in salt glands and other secretory epithelia. 相似文献
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SA Carrasco 《New Zealand journal of zoology.》2013,40(1):32-45
This study combined morphological and morphometric information on egg clutches, egg capsules and paralarvae of two sympatric coastal octopuses from New Zealand waters, Octopus huttoni and Pinnoctopus cordiformis, to provide species-specific traits to identify their early life stages obtained from field surveys. Eggs of O. huttoni (2.5 mm length; 1 mm width) were entwined with one another forming strings that ranged from 11 to 25.8 mm in length. Eggs of P. cordiformis (6.4 mm length; 1.5 mm width) were significantly bigger than those of O. huttoni and were grouped in small clusters of about seven eggs. Paralarvae O. huttoni and P. cordiformis differed in hatching size (1.4 mm versus 3.1 mm mantle length), number of suckers per arm (four versus eight), number of lamellae per outer demibranch (five versus ten) and arrangements of chromatophores in the body surface (29 to 59 versus 91 to 179), respectively. The morphological traits described in hatchlings from the laboratory allowed comparisons with field-collected paralarvae, suggesting that such characters were reliable species-specific patterns to enable a consistent differentiation between the early life stages of these two sympatric species, even in the absence of the brooding female. 相似文献
6.
Endothelial progenitor cells (EPC) participate in revascularization and angiogenesis. EPC can be cultured in vitro from mononuclear cells of peripheral blood, umbilical cord blood or bone marrow; they also can be transdifferentiated from mesenchymal stem cells (MSC). We isolated EPCs from Wharton's jelly (WJ) using two methods. The first method was by obtaining MSC from WJ and characterizing them by flow cytometry and their adipogenic and osteogenic differentiation, then applying endothelial growth differentiating media. The second method was by direct culture of cells derived from WJ into endothelial differentiating media. EPCs were characterized by morphology, Dil-LDL uptake/UEA-1 immunostaining and testing the expression of endothelial markers by flow cytometry and RT-PCR. We found that MSC derived from WJ differentiated into endothelial-like cells using simple culture conditions with endothelium induction agents in the medium. 相似文献
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R. R. Binning S. A. Lefko A. Y. Millsap S. D. Thompson T. M. Nowatzki 《Journal of Applied Entomology》2010,134(7):551-561
Susceptibility of Diabrotica virgifera virgifera (LeConte) larvae to DAS‐59122‐7 maize was evaluated using a laboratory technique that measures rootworm survival to adulthood on maize seedlings. This method produces direct measures of larval susceptibility using realistic exposure to the same range of insecticidal protein concentrations found in field‐grown DAS‐59122‐7 maize roots. First, second and third instars were reared to adulthood on DAS‐59122‐7 maize seedlings or a non‐transgenic, near‐isoline maize. Data on survival, adult gender ratio, adult weight and median emergence were collected. Overall, larval susceptibility to DAS‐59122‐7 maize was lower than earlier predictions ( Storer et al. 2006 ). Neonate survival on DAS‐59122‐7 maize was approximately 33% of isoline survival after 17 days, and the same 33% recovered and developed to adulthood when the isoline maize was substituted. Survival rate on DAS‐59122‐7 maize increased with instar. The mean survivorship was 0.5%, 26% and 65% when exposure to DAS‐59122‐7 maize began at the first, second and third instars, respectively. Exposure to DAS‐59122‐7 maize led to sub‐lethal effects on adult gender ratio, weight and median emergence. These effects decreased when exposure to DAS‐59122‐7 maize began at later instars. The killing effect of DAS‐59122‐7 maize on rootworm larvae appeared to result from the combined chronic effects and absence of a suitable host as perceived by the larvae. The relevance of these data and the methodology of estimating rootworm susceptibility to plant‐incorporated protectants are discussed in the context of the US Environmental Protection Agency’s functional definition of ‘high dose’ and use of refuge for resistance management ( EPA 1998a ). Based on these results it is evident that DAS‐59122‐7 maize does not meet the functional definitions of high dose as described by EPA (1998a,b) and ILSI (1999) , and the utility of refuge, refuge size and refuge placement for delaying rootworm resistance should be further investigated. 相似文献
10.
MORAIS PAULO AMORIM ANTÓNIO VIEIRA DA SILVA CLÁUDIA RIBEIRO TERESA COSTA SANTOS JORGE AFONSO COSTA HELOÍSA 《Journal of genetics》2015,94(3):509-512
Journal of Genetics - 相似文献