Isolation and characterization of microsatellites in Pacific white shrimp Penaeus (Litopenaeus) vannamei

Five polymorphic microsatellite loci were characterized for Penaeus (Litopenaeus) vannamei. Loci were isolated using a partial Sau3A1 genomic library by the sequencing of randomly selected clones and by a biotinylated (CT)₁₀ and (GT)₁₀ probes screening procedure. The last strategy resulted in the most useful data. About 40% of the clones showed a previously reported satellite/microsatellite (PVS1), reducing the chance of finding new microsatellite regions. Whereas two of the microsatellite loci with more than 10 alleles will be useful for mating analysis in a breeding program, the others might prove useful for population genetic studies.     

The NADP-dependent trifunctional methylenetetrahydrofolate dehydrogenase purified from mouse liver is immunologically distinct from the mouse NAD-dependent [corrected] bifunctional enzyme

Methylenetetrahydrofolate dehydrogenase - methenyltetrahydrofolate cyclohydrolase - formyltetrahydrofolate synthetase was purified to homogeneity from mouse liver, taking advantage of its very high affinity for 2',5'-ADP-Sepharose. Antibodies raised to this trifunctional enzyme and to the bifunctional NAD-dependent dehydrogenase-cyclohydrolase from mouse Ehrlich ascites tumour cells were found not to cross-react with the purified proteins on Western blots. Each of these polyclonal antibodies detects the appropriate protein in extracts of Ehrlich ascites tumour cells after sodium dodecyl sulfate - polyacrylamide gel electrophoresis and electrophoretic transfer of the proteins to nitrocellulose. The procedure has also been used to obtain a purified preparation of the trifunctional enzyme from human liver obtained at autopsy.     

Cell kinetics of a chondrosarcoma.

The cell kinetics of the transplantable DC-II mouse chondrosarcoma have been studied by the pulse labelled mitoses method. The analysis gave the following estimates for the phases of the cell cycle: G1, 10-5 hr; S, 9-5 hr; G2, 4 hr with an intermitotic time of 23-5 hr. Consideration of the overall growth of the tumour indicated that the growth fraction and cell loss factor both had values of about 0-5. The results are compared with cell kinetic data from sarcomas and other cartilage tissues.     

The response of stream periphyton to Pacific salmon: using a model to understand the role of environmental context

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Optimal conditions for primary production in a polymictic tropical lake (Lake Xolotlán,Nicaragua)

From 1987 to 1993 we assessed the variation of phytoplankton biomass, underwater irradiance and primary production in Lake Xolotlán (L. Managua, Nicaragua). Chlorophyll- a averaged 65 mg m-3 and maximum and minimum concentrations were 120 and 30 mg m-3, respectively. The variability over depths and weeks was low (CV < 20%). There were strong correlations between particulate carbon and chlorophyll- a (the ratio ≈ 100: 1) and between particulate carbon and particulate nitrogen and phosphorus (the ratio ≈ 100: 11: 1). Gross primary production averaged 6.8 g C m-2 d- 1 and was stable over the years (CV ≈ 10%). Algal cell growth was approximately 4–5 g C m-2 d- 1. Productivity was limited only by the availability of underwater light and the depth of the photic zone was mainly regulated by the chlorophyll- a concentration. Therefore, areal photic zone chlorophyll- a was the only factor directly correlated to the integral photosynthetic activity but, contrary to theoretical models, the production did not increase in proportion to chlorophyll- a. Data from African lakes show a similar pattern. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cell Kinetics and the Control of Growth In Long Bones

The cell kinetics of the cartilage growth plate are outlined and discussed in terms of the probable levels of control on the system. Possible mechanisms of growth control at the cellular level are examined for (i) the rate of cell division in the proliferation zone, (ii) the command to differentiate that limits the size of the proliferation zone and (iii) the ageing process in the cartilage plate. the evidence of cell kinetics does not point unequivocally to any particular mechanism.