Habitat preference in the critically endangered yellow‐tailed woolly monkey (Lagothrix flavicauda) at La Esperanza,Peru

Habitat loss is one of the main threats to wildlife. Therefore, knowledge of habitat use and preference is essential for the design of conservation strategies and identification of priority sites for the protection of endangered species. The yellow‐tailed woolly monkey (Lagothrix flavicauda Humboldt, 1812), categorized as Critically Endangered on the IUCN Red List, is endemic to montane forests in northern Peru where its habitat is greatly threatened. We assessed how habitat use and preference in L. flavicauda are linked to forest structure and composition. The study took place near La Esperanza, in the Amazonas region, Peru. Our objective was to identify characteristics of habitat most utilized by L. flavicauda to provide information that will be useful for the selection of priority sites for conservation measures. Using presence records collected from May 2013 to February 2014 for one group of L. flavicauda, we classified the study site into three different use zones: low‐use, medium‐use, and high‐use. We assessed forest structure and composition for all use zones using 0.1 ha Gentry vegetation transects. Results show high levels of variation in plant species composition across the three use zones. Plants used as food resources had considerably greater density, dominance, and ecological importance in high‐use zones. High‐use zones presented similar structure to medium‐ and low‐use zones; thus it remains difficult to assess the influence of forest structure on habitat preference. We recommend focusing conservation efforts on areas with a similar floristic composition to the high‐use zones recorded in this study and suggest utilizing key alimentation species for reforestation efforts.     

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.     

RNA unwinding in translation: assembly of helicase complex intermediates comprising eukaryotic initiation factors eIF-4F and eIF-4B.

Ribosome binding to mRNA requires the concerted action of three initiation factors, eIF-4A, eIF-4B, and eIF-4F, and the hydrolysis of ATP in a mechanism that is not well understood. Several lines of evidence support a model by which these factors bind to the 5' end of mRNA and unwind proximal secondary structure, thus allowing 40S ribosomal subunits to bind. We have previously used an unwinding assay to demonstrate that eIF-4A or eIF-4F in combination with eIF-4B functions as an RNA helicase. To elucidate the molecular mechanism of RNA unwinding, we used a mobility shift electrophoresis assay which allows the simultaneous analysis of unwinding and complex formation between these factors and RNA. eIF-4F forms a stable complex (complex A) with duplex RNA in the absence of ATP. Addition of eIF-4B results in the formation of a second complex (complex B) of slower mobility in the gel. In the presence of ATP, both complexes dissociate, concomitant with the unwinding of the duplex RNA. We present evidence to suggest that unwinding occurs in a processive as opposed to distributive manner. Thus, we conclude that helicase complexes that are formed in the absence of ATP on duplex RNA translocate processively along the RNA in an ATP-dependent reaction and melt secondary structure. These helicase complexes therefore represent intermediates in the unwinding process of mRNA that could precede ribosome binding.     

Induction of methotrexate release from rat hepatocytes in suspension by alpha-adrenergic agents: involvement of calcium and metabolic energy

Hepatocytes in suspension which have accumulated [3H]methotrexate release the antifolate compound into the medium upon exposure to alpha-adrenergic agents. In the presence of metabolic poisons, such as sodium azide, dinitrophenol, or dicumarol, the release of methotrexate is attenuated, indicating that integrity of the cellular metabolic apparatus is required for response to the hormonal stimulus. In the presence of millimolar concentrations of the organic acid, probenecid, release of cellular methotrexate may be reduced (1 mM probenecid) or eliminated (2 mM probenecid), suggesting the involvement of a "membrane carrier." Microtubule poisons such as vincristine, vinblastine, and griseofulvin do not modify epinephrine + isobutyl methyl xanthine (IBMX)-induced release of methotrexate. The involvement of calcium in release of methotrexate from the hepatocyte is substantiated by a dose-dependent response to the calcium ionophore, A23187, in the presence of calcium, with a lack of response in the absence of calcium. These effects of A23187 are not related to inhibition of methotrexate influx. Other putative "calcium antagonists" such as tetracaine, neomycin sulfate, and 3,4,5-trimethoxybenzoic acid [8-(diethylamino)octyl ester], do not interfere with epinephrine + IBMX-induced release of [3H]methotrexate, suggesting that these agents may not be effective probes of calcium flux in the liver cell.