Methylarginine efflux in nutrient-deprived yeast mitigates disruption of nitric oxide synthesis

Amino Acids - Protein arginine N-methyltransferases (PRMTs) have emerged as important actors in the eukaryotic stress response with implications in human disease, aging, and cell signaling....     

Enhanced transformation of tomato co-cultivated with Agrobacterium tumefaciens C58C1Rifr::pGSFR1161 in the presence of acetosyringone

Summary Explants of tomato (Lycopersicon esculentum Mill cv. Ailsa Craig) were co-cultivated with Agrobacterium tumefaciens C58C1Rif^r::pGSFR1161 in the presence of 20 (M acetosyringone). Transformed root clones were selected on kanamycin medium and the presence of the nptII gene in the plant DNA confirmed by the polymerase chain reaction. Root clones derived from acetosyringone treatment grew more vigorously in the presence of kanamycin and synthesized a greater amount of NPT-II enzyme. The conclusion is that acetosyringone treatment enhances the transformation process, possibly by stimulating multiple insertions of the T-DNA into the host genome.Abbreviations AS acetosyringone - CTAB hexadecyltrimethylammonium bromide - EDTA ethylenediaminetetraacetic acid - ELISA enzyme-linked immunosorbant assay - MS Murashige and Skoog (1962) medium - PCR polymerase chain reaction     

Do physicians locate as spatial competition models predict? Evidence from Alberta.

This article analyses how physicians choose locations of practice in response to spatial competition forces and considers the implications of such choices for public policy to alleviate shortages of practitioners in rural areas. The predicted geographic distribution of physicians, as determined through spatial competition modelling, was compared with the actual distribution of physicians in 1990 among Alberta''s 19 census divisions. Physicians were found to respond to spatial competition forces in choosing where to practise, with the qualification that 1 urban patient had a demand weight equal to 2.32 rural patients. A policy to attract more physicians to rural areas by means of income subsidies is technically feasible but expensive. The high cost means that alternative policies such as a bigger and more effective ambulance network to transport patients to medical centres should become the focus of public policies to improve health care in rural areas.     

THE EVOLUTIONARY HISTORY OF PARTHENOGENETIC CNEMIDOPHORUS LEMNISCATUS (SAURIA: TEIIDAE). II. MATERNAL ORIGIN AND AGE INFERRED FROM MITOCHONDRIAL DNA ANALYSES

Restriction endonuclease analyses were performed on mitochondrial DNAs (mtDNAs) representing unisexual parthenogenetic (cytotypes A, B, and C) and bisexual (cytotypes D and E) populations of Amazonian lizards presently regarded as Cnemidophorus lemniscatus. The results of mtDNA cleavage map comparisons among these C. lemniscatus indicated that (1) there was no cleavage site variation among the unisexuals, (2) mtDNAs from the bisexual cytotypes D and E differed in sequence from one another by about 13%, and (3) mtDNAs from cytotypes A–C differed from those of cytotype D by about 5% and from those of cytotype E by about 13%. Higher resolution restriction fragment size comparisons confirmed the high degree of similarity among the unisexual mtDNAs, but identified 12 cleavage site variants among the 13 cytotype D mtDNAs examined. Both cladistic and phenetic (UPGMA) analyses of the data indicate that the unisexual and cytotype D mtDNAs form a single clade, suggesting that a female of cytotype D was the maternal progenitor of the unisexuals. The similarity among the unisexual mtDNAs and the variability among those of cytotype D suggest that the three unisexual cytotypes arose recently from a common maternal lineage. The mtDNA variability observed among cytotype D individuals has a strong geographic component, suggesting that the unisexuals arose from one or a few geographically proximal populations. The mtDNA comparisons also support the conclusion, based on allozyme comparisons (Sites et al., 1990, this issue), that cytotypes D and E, although presently allocated to C. lemniscatus, are separate species.     

Organization of the vimentin system and its spatial relationship to the microtubule complex during the division of mammalian cells growing attached and in suspension

We have used immunofluorescence staining with antibodies that detect vimentin, tubulin and the centrioles to compare the distributions of these respective antigens during the division of several suspension and attached cultured cells. Our observations demonstrate that 1) from distinct interphase organizations in suspension and attached cells, the vimentin system consistently rearranges with the onset of mitosis into a filamentous cage-like structure enclosing the spindle, 2) during cytokinesis, the polar centrosomes relocalize near the midbody in suspension cells while they remain at the pole opposite to it in attached cells, and 3) the vimentin cage is disintegrated and aggregated on each side of the midbody during cytokinesis in lymphoid cells but may be retained in other suspension cells.