Aldosterone as a renal growth factor

Aldosterone regulates blood pressure through its effects on the cardiovascular system and kidney. Aldosterone can also contribute to the development of hypertension that leads to chronic pathologies such as nephropathy and renal fibrosis. Aldosterone directly modulates renal cell proliferation and differentiation as part of normal kidney development. The stimulation of rapidly activated protein kinase cascades is one facet of how aldosterone regulates renal cell growth. These cascades may also contribute to myofibroblastic transformation and cell proliferation observed in pathological conditions of the kidney. Polycystic kidney disease is a genetic disorder that is accelerated by hypertension. EGFR-dependent proliferation of the renal epithelium is a factor in cyst development and trans-activation of EGFR is a key feature in initiating aldosterone-induced signalling cascades. Delineating the components of aldosterone-induced signalling cascades may identify novel therapeutic targets for proliferative diseases of the kidney.     

ORDINATION AND CLASSIFICATION OF WESTERN OAK FORESTS IN OKLAHOMA

Ordination and classification techniques were used to analyze patterns of forest vegetation, species diversity, and soil type in the Wichita Mountains Wildlife Refuge of southwestern Oklahoma. Cluster analysis based on tree species produced three general community types: 1) Quercus stellata-Q. marilandica forests; 2) Q. stellata forests; and 3) mesophytic forests. A polar ordination produced a gradient of vegetation that corresponded to a moisture gradient. Many high diversity forests were located on loamy drainageway soils or north facing slopes. Tree species diversity (H') was inversely related to the importance of Quercus stellata. Cluster analysis based on species composition of the tree seedlings produced four general community types: 1) Q. marilandica type; 2) Q. marilandica-Q. stellata-Juniperus virginiana type; 3) Ulmus americana-Celtis reticulata-Bumelia lanuginosa type; and 4) Acer saccharum type. The third seedling type occurred almost exclusively on loamy drainageway soils. There was no relationship between stand location on the first axis of the tree ordination and the first axis of the seedling ordination suggesting that trees and seedlings respond differently along the moisture gradient.     

Antigenic diversity of the S-layer proteins from pathogenic strains of Aeromonas hydrophila and Aeromonas veronii biotype sobria.

The antigenic relatedness of paracrystalline surface array proteins with subunit molecular weights of approximately 52,000 from isolates of Aeromonas hydrophila and Aeromonas veronii biotype sobria belonging to a single heat-stable serogroup was examined. Enzyme-linked immunosorbent assay and immunoblotting with two different polyclonal antisera against surface exposed and non-surface-exposed epitopes of the S-layer protein from A. hydrophila TF7 showed that the S-layer proteins of the mesophilic aeromonads were antigenically diverse. NH2-terminal amino acid sequence analysis of four antigenically different proteins showed that while the proteins were structurally related, they differed in primary sequence. Absorption experiments with heterologous live cells showed that cross-reactive epitopes were in non-surface-exposed regions of the S-layer proteins, while absorption with homologous live cells showed that the immunodominant epitopes of the S-layer protein of strain TF7 were strain specific and exposed on the surface of the native, tetragonal array produced by this strain. Proteolytic digestion of the TF7 S-layer protein with trypsin, chymotrypsin, or endoproteinase Glu-C produced an amino-terminal peptide of approximate Mr 38,000 which was refractile to further proteolytic cleavage under nondenaturing conditions. This peptide carried the immunodominant surface-exposed region of the protein, and chemical cleavage with cyanogen bromide further mapped the portion of these surface-exposed epitopes to a peptide of approximate Mr 26,000, part of which maps within the Mr 38,000 protease-resistant NH2-terminal peptide.     

Use of space and habitats by meadow voles at the home range,patch and landscape scales

Using capture/recapture methods, we examined the spatial usage patterns of Microtus pennsylvanicus within and between experimentally created habitat patches of three sizes (1.0, 0.25 and 0.0625 ha) and between a 20-ha fragmented and a 20-ha continuous habitat landscape. We tested the prediction that home ranges near patch edges would be qualitatively different from those in patch interiors, and that the edge:interior habitat ratio could be used to make predictions concerning the dispersion and spatial use of individuals occupying different sized patches and between landscapes with different habitat structure. We found adult females on patch edges to have larger and more exclusive home ranges, larger body sizes, longer residence times, and to reproduce at a higher frequency than those in patch interiors. These edge effects also appeared to be largely responsible for the greater proportion of larger, reproductive females we found in small than larger patches and in the fragmented than in the continuous habitat (control) landscape. The selection of higher quality edge habitats by dominant females and the relegation of sub-dominants to patch interiors provides an explanation for the observed differences in the distribution and performance of females over patches and between landscapes.     

Detection of a HindIII restriction fragment length polymorphism in the human phenol sulfotransferase (STP) locus

The gene encoding human phenol-preferring phenol sulfotransferase (STP) has been cloned and mapped to chromosome 16p. A HindIII RFLP in this gene is described.     

Effect of mitochondrial DNA (mtDNA) type on pregnancy rate after embryo transfer in rats

Because the mtDNA is maternally inherited, embryos resulting from matings or artificial inseminations have the same type of mtDNA as that of the mother. However, when embryos are transferred the mtDNA of the embryos may be different to that of the recipient and this may interfere with maternal recognition and the establishment of pregnancy. This study was done to determine whether differences in the mtDNA between embryos and recipients would influence the survival to term of transferred embryos.A total of 1,220 rat embryos were recovered from non-superovulated donors of known mtDNA type. The number and distribution of developmental stages of embryos collected from 51 rats of mtDNA type A (n = 595) were not different (P>0.05) from those collected from 50 rats of mtDNA type B (n = 625). The overall pregnancy rate after transfer of embryos to pseudopregnant rats was 54% (26 48 ). The pregnancy rate was not affected (P>0.05) by the type of mtDNA of the recipient or of the embryo, and the interaction between mtDNA type of embryos and recipients was also not significant (P>0.05). Embryonic survival to birth was low (78 622 , 12.5%) but was not affected (P>0.05) by the type of mtDNA of the recipient (A = 28 250 ; B = 50 372 ) or of the embryo (A = 41 306 ; B = 37 316 ). Survival of pups to weaning was affected by the type of mtDNA of the embryo (P < 0.01) but not by the type of mtDNA of the recipient (P>0.05) and the interaction between mtDNA type of embryos and recipients was also not significant (P>0.05). More pups (P < 0.005) derived from donor rats of mtDNA type A (34 41 ) survived to weaning age than pups from donor rats of mtDNA type B (18 37 ). These results indicate that differences in the type of mtDNA between embryos and recipients do not interfere with establishment of pregnancy in pseudopregnant recipients.     

Recombinant Human Albumin in Cell Culture: Evaluation of Growth-Promoting Potential for NRK and SCC-9 Cells In Vitro

Serum-derived albumin has for a long time been used in cell culture media, but the exact role of albumin and/or impurities bound to albumin has not been precisely defined. In this study, recombinant human albumin was evaluated for its growth-promoting activity on two cell lines, NRK and SCC-9. For NRK cells, the recombinant human albumin was found to exert an inhibitory effect. The fact that fatty acid free HSA was also inhibitory while HSA fraction V was stimulatory suggested a role for fatty acids or some other bound moieties in growth stimulation by HSA fraction V. Addition of oleic acid, cholesterol, phosphatidylcholine, phosphatidylserine or a combination of these lipids, however, did not significantly improve the growth stimulating activity of either fatty acid free HSA or the recombinant human albumin. For SCC-9 cells, both recombinant human albumin and fatty acid free HSA showed slight stimulation (although they were not as active as HSA fraction V), suggesting that in some cell systems, the albumin molecule per se may promote cell growth and survival. This revised version was published online in July 2006 with corrections to the Cover Date.