Evidence for a highly specific protein kinase phosphorylating two strongly acidic proteins of yeast 60 S ribosomal subunit

Two distinct, cyclic AMP-independent protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) from yeast have been isolated and highly purified. The first of the enzymes, protein kinase 1 A, phosphorylates casein and phosvitin, and its cellular protein substrate is unknown. The second enzyme, protein kinase 1 B, phosphorylates two strongly acidic proteins, L44 and L45, of the 60 S ribosomal subunit.     

Survey of yeast mastitis in dairy herds of small-type farms in the Lublin region,Poland

The purpose of this study was to isolate fungi from the quarter milk of cow udders in 9 dairy farms. The samples were collected between May 1996 and April 2000 in the Lublin region. Six hundred and four milk samples collected from the quarters of 172 cows with clinical and subclinical mastitis were examined. Milk samples were plated as soon as possible on blood agar (BA), Mac Conkey agar, aesculin-tallium acetate-crystal violet blood agar, and Sabouraud agar with chloramphenicol and gentamicin. Fifty eight (9.6%) of the samples were positive for fungi. All of the fungal isolates were yeasts of the genera Candida, Rhodotorula and Trichosporon. We also isolated Streptococcus agalactiae (4.9%), Str. spp.(6.4%), Staphylococcus aureus (10.4%), coagulase-negative staphylococci-CNS (36.6%), Escherichia coli (3.5%), other microorganisms (2.6%) and no growth (25.8%). This revised version was published online in June 2006 with corrections to the Cover Date.     

Lead levels in bone and hair of rats treated with lead acetate

The use of hair and bone as media in evaluation of lead exposure was investigated in this study. For 12–16 wk rats were given tap water containing lead acetate in the following concentrations: 41.7 mg Pb/L, 83.3 mg Pb/L, and 166.6 mg Pb/L. The animals were sacrificed every 4 wk and their tibia bones and hair were collected for determination of lead content. In control animals, the lead level amounted to 1.2 μg/g (range 0.8–1.3 μg/g) and 0.7 μg/g (range 0.4–2.0 μg/g) in bone and hair, respectively. In the treated rats the accumulation of lead in bone and hair occurred in a dose-dependent manner. A positive corelation (r=0.876) was established between the lead levels in bone and hair of the rats. The regression equation was as follows: μg Pb/g bone=0.842×μg Pb/g hair+1.868. After discontinuation of exposure, a significant decrease in the lead content in bone and hair was noticed. About 9 wk after cessation of treatment, the lead content in hair declined to the pre-exposure level, but 64% of the maximal lead concentration did remain in bone. The results of this study indicate that during a continuous exposure the lead level in hair reflects its content in bone. Such phenomena did not occur during the postexposure period.     

Membrane Potential Mediates H+-ATPase Dependence of ``Degradative Pathway' Endosomal Fusion

In some epithelial cell lines, the uptake and degradation of proteins is so pronounced as to be regarded as a specialized function known as ``degradative endocytosis.' The endosomal pathways of the renal proximal tubule and the visceral yolk sac share highly specialized structures for ``degradative endocytosis.' These endosomal pathways also have a unique distribution of their H⁺-ATPase, predominantly in the subapical endosomal pathway. Previous studies provide only indirect evidence that H⁺-ATPases participate in endosomal fusion events: formation of vesicular intermediates between early and late endosomes is H⁺-ATPase dependent in baby hamster kidney cells, and H⁺-ATPase subunits bind fusion complex proteins in detergent extracts of fresh rat brain. To determine directly whether homotypic endosomal fusion is H⁺-ATPase dependent, we inhibited v-type H⁺-ATPase during flow cytometry and cuvette-based fusion assays reconstituting endosomal fusion in vitro. We report that homotypic fusion in subapical endosomes derived from rat renal cortex, and immortalized visceral yolk sac cells in culture, is inhibited by the v-type H⁺-ATPase specific inhibitor bafilomycin A1. Inhibition of fusion by H⁺-ATPase is mediated by the membrane potential as collapsing the pH gradient with nigericin had no effect on homotypic endosomal fusion, while collapsing the membrane potential with valinomycin inhibited endosomal fusion. Utilizing an in vitro reconstitution assay this data provides the first direct evidence for a role of v-type H⁺-ATPase in mammalian homotypic endosomal fusion. Received: 29 October 1996/Revised: 8 December 1997     

The Ising model in physics and statistical genetics

Interdisciplinary communication is becoming a crucial component of the present scientific environment. Theoretical models developed in diverse disciplines often may be successfully employed in solving seemingly unrelated problems that can be reduced to similar mathematical formulation. The Ising model has been proposed in statistical physics as a simplified model for analysis of magnetic interactions and structures of ferromagnetic substances. Here, we present an application of the one-dimensional, linear Ising model to affected-sib-pair (ASP) analysis in genetics. By analyzing simulated genetics data, we show that the simplified Ising model with only nearest-neighbor interactions between genetic markers has statistical properties comparable to much more complex algorithms from genetics analysis, such as those implemented in the Allegro and Mapmaker-Sibs programs. We also adapt the model to include epistatic interactions and to demonstrate its usefulness in detecting modifier loci with weak individual genetic contributions. A reanalysis of data on type 1 diabetes detects several susceptibility loci not previously found by other methods of analysis.     

Familial juvenile hyperuricemic nephropathy: localization of the gene on chromosome 16p11.2-and evidence for genetic heterogeneity

Familial juvenile hyperuricemic nephropathy (FJHN), is an autosomal dominant renal disease characterized by juvenile onset of hyperuricemia, gouty arthritis, and progressive renal failure at an early age. Using a genomewide linkage analysis in three Czech affected families, we have identified, on chromosome 16p11.2, a locus for FJHN and have found evidence for genetic heterogeneity and reduced penetrance of the disease. The maximum two-point LOD score calculated with allowance for heterogeneity (HLOD) was 4.70, obtained at recombination fraction 0, with marker D16S3036; multipoint linkage analysis yielded a maximum HLOD score of 4.76 at the same location. Haplotype analysis defined a 10-cM candidate region between flanking markers D16S501 and D16S3113, exhibiting crossover events with the disease locus. The candidate interval contains several genes expressed in the kidney, two of which-uromodulin and NADP-regulated thyroid-hormone-binding protein-represent promising candidates for further analysis.     

Influence of immobilized quaternary ammonium group surface density on antimicrobial efficacy and cytotoxicity

Bacterial colonization of medical devices causes infections and is a significant problem in healthcare. The use of antibacterial coatings is considered as a potential solution to this problem and has attracted a great deal of attention. Using concentration density gradients of immobilized quaternary ammonium compounds it was demonstrated that a specific threshold of surface concentration is required to induce significant bacterial death. It was determined that this threshold was 4.18% NR₄⁺ bonded nitrogen with a surface potential of + 120.4 mV. Furthermore, it is shown for the first time that adhesion of constituents of the culture medium to the quaternary ammonium modified surface eliminated any cytotoxicity towards eukaryotic cells such as primary human fibroblasts. The implications of this type of surface fouling on the antimicrobial efficacy of surface coatings are also discussed.