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271.
Mona El Agoze Marylène Poirié Georges Périquet 《Entomologia Experimentalis et Applicata》1995,75(3):251-255
In most insect species where double matings occur, sperm from the second male preferentially fertilize subsequent eggs. However,
we demonstrate here that, as already shown for some other hymenopteran species, this is not the case in the ichneumonid waspDiadromus pulchellus (Wesmeal): sperm from the first male usually father all the female progeny. This precedence of the first male sperm is also
observed in double matings involving an haploid male and a diploid sterile male, whichever is the first mating male. We discuss
the consequences of this phenomenon from an evolutionary point of view. 相似文献
272.
A dynamic nonlinear optimization analysis of subsistence patterns of the Mountain Pima of Chihuahua, Mexico, included requirements for adequate amounts of calories, calcium, vitamin A, vitamin C, and balanced protein. Two methods of incorporating nonenergy nutritional needs into a time minimization program were compared. The first was a constraint model with sharp boundaries between adequacy and fatality. The second involved multiplying the total work time by a series of nutrient indexing factors. Each factor was calculated as a function of the ratio between the recommended and actual rates of intake for all months and nutrients considered. Oxalate composition of some resources and seasonal variation in resource availability were taken into account. Two sets of data were analyzed, one for a year of adequate rainfall, the other for a year of severe drought. The predictions of the indexing model agreed more closely with observed intake patterns than did the predictions of the constraint model. 相似文献
273.
The effects of inorganic mercury (HgII) and methylmercury (MeHg) on the colonization of artificial substrates by periphytic
diatoms were studied using indoor freshwater microcosms. These consisted of a mixed biotope– water column + natural sediment
– with rooted macrophyte cuttings (Elodea densa) and benthic bivalve molluscs (Corbicula fluminea).The periphyton was collected
on glass slides in the water column after 34and 71 days. The two Hg sources were introduced either by daily additions to the
water column, or once at the beginning into the sediment, using two nominal concentrations: water column, 0.5 μgL-1 and 2 μg L-1 for both compounds: sediment, 0.5 mg kg-1 (fw) and 2 mgkg-1 (fw) for MeHg and 1 mg kg-1 (fw) and 10 mgkg-1 (fw) for HgII. Several complementary criteria were used to analyse the structural and functional perturbations induced: cell
density, species richness, diatom size, relative abundance. Exposure to MeHg added to the water column resulted in reduced
cell density and changes in species composition with enhancement of e.g. Fallacia pygmaea or Nitzschia palea; inorganic Hg
had less effect on the population structure. After contamination via the sediment, the effects of the two compounds were less
pronounced than for the water source.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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278.
Nathalie Doerflinger Catherine Linder Karim Ouahchi Gabor Gyapay Jean Weissenbach Denis Le Paslier Philippe Rigault Samir Belal Christiane Ben Hamida Faycal Hentati Mongi Ben Hamida Massimo Pandolfo Stephano DiDonato Ronald Sokol Herbert Kayden Pierre Landrieu Alexandra Durr Alexis Brice Fran?oise Goutières Alfried Kohlschütter Pascal Sabouraud Ali Benomar Mohamed Yahyaoui Jean-Louis Mandel Michel Koenig 《American journal of human genetics》1995,56(5):1116-1124
Ataxia with vitamin E deficiency (AVED) is an autosomal recessive disease characterized clinically by neurological symptoms with often striking resemblance to those of Friedreich ataxia. This disorder has been reported previously as familial isolated vitamin E deficiency. We have mapped recently the AVED locus to a 5-cM confidence interval on chromosome 8q by homozygosity mapping in six Mediterranean families. We have now analyzed six new and two previously described families and demonstrate genetic homogeneity despite important clinical variability and wide geographic origins. Analysis of nine new tightly linked microsatellite markers, including four characterized in this study, revealed a predominant but not unique mutation in northern African populations, where this condition is more frequent. Haplotype analysis but also classical recombinations allowed us to refine the AVED position to a 1-cM interval. A YAC contig over this interval was constructed from marker STSs and YAC fingerprint data, in order to facilitate the search of the AVED gene. 相似文献
279.
Summary A protocol was developed for the preparation of Cucumis sativus var Straight 8 protoplasts that incorporates a two-step Ficoll® gradient and results in a high percentage of viable, debris-free protoplasts suitable for the transient expression of foreign genes. Polyethylene glycol and electroporation were compared for their effect on protoplast transfection with commonly used reporter genes. Using a polyethylene glycol method, cucumber protoplasts transfected with a plasmid containing the -glucuronidase gene showed high expression levels, while protoplasts transfected with a plasmid containing the chloramphenicol acetyl transferase gene showed levels of activity that were barely distinguishable from mock-transfected controls. Tomato ringspot virus genomic RNA was also transfected into the protoplasts, and the assembly of viral particles was confirmed. 相似文献
280.
Emmanuel Martin Valère Cacheux Hélène Cavé Jean Michel Lapierre Denis Le Paslier Bernard Grandchamp 《Human genetics》1995,96(6):668-670
CDKN4/p27Kip1 is a cyclin-dependent kinase (Cdk) inhibitor implicated in G1 phase arrest, which negatively regulates G1 phase progression in response to TGF, and might represent a tumor suppressor gene. We report here the chromosomal assignment of the human CDKN4 gene to chromosome 12p12.3 in close proximity to highly polymorphic microsatellite markers. 相似文献