Interactions ofCandida albicans with bacteria and salivary molecules in oral biofilms

The yeastCandida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells.C. albicans andCandida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind toStreptococcus gordonii NCTC 7869 while two otherCandida species (Candida krusei andCandida kefyr) do not. Adherence ofC. albicans was greatest when the yeast had been grown at 30° C to mid-exponential growth phase. For 21 strains ofC. albicans there was a positive correlation between the ability to adhere toS. gordonii and adherence to experimental salivary pellicle. Whole saliva either stimulated or slightly inhibited adherence ofC. albicans toS. gordonii depending on the streptococcal growth conditions. The results suggest that the major salivary adhesins and coaggregation adhesins ofC. albicans are co-expressed.     

Inhibin production by macaque granulosa cells from pre- and periovulatory follicles: regulation by gonadotropins and prostaglandin E2.

Although inhibin (IN) is secreted by granulosa cells (GC) of preovulatory follicles, the major source of immunoreactive IN circulating during the primate ovarian cycle is the corpus luteum. The aims of this study were (1) to investigate culture conditions for optimal IN production by luteinized GC (LGC) from rhesus monkeys and (2) to compare IN and progesterone (P) production by nonluteinized GC (NGC) and LGC in response to putative agonists. Animals were treated for up to 9 days with human menopausal gonadotropins to promote the development of multiple preovulatory follicles. GC were obtained from large follicles before (NGC) or 27 h after (LGC) an ovulatory injection of hCG. For Aim 1, cells were cultured in Hams F-10 medium +/- hCG (100 ng/ml) with or without the addition of insulin/transferrin/selenium, 10% fetal bovine serum, or 10% Serum-Plus (JRH Biosciences, Lenexa, KS). Medium was changed on Days 1, 2, 4, 6, and 8, and IN and P concentrations were determined by RIA. Basal (unstimulated) IN production by LGC was enhanced and maintained for 6-8 days in the presence of serum, but rapidly declined in the absence of serum. In contrast, basal P secretion declined regardless of exposure to serum. Human CG consistently increased (p less than 0.05) IN production only in the presence of serum but stimulated (p less than 0.05) P production under all conditions. For Aim 2, cells were cultured for 4 days in Ham's F-10 medium + 10% macaque serum +/- hCG (100 ng/ml), hFSH (100 ng/ml), prostaglandin E2(PGE2; 14 microns), or dibutyryl(db)-cAMP (5 mM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Control of cell volume in the J774 macrophage by microtubule disassembly and cyclic AMP

We have explored the possibilities that cell volume is regulated by the status of microtubule assembly and cyclic AMP metabolism and may be coordinated with shape change. Treatment of J774.2 mouse macrophages with colchicine caused rapid microtubule disassembly and was associated with a striking increase (from 15-20 to more than 90 percent) in the proportion of cells with a large protuberance at one pole. This provided a simple experimental system in which shape changes occurred in virtually an entire cell population in suspension. Parallel changes in cell volume could then be quantified by isotope dilution techniques. We found that the shape change caused by colchicine was accompanied by a decrease in cell volume of approximately 20 percent. Nocodozole, but not lumicolchicine, caused identical changes in both cell shape and cell volume. The volume loss was not due to cell lysis nor to inhibition of pinocytosis. The mechanism of volume loss was also examined. Colchicine induced a small but reproducible increase in activity of the ouabain-sensitive Na(+), K(+)-dependent ATPase. However, inhibition of this enzyme/transport system by ouabain did not change cell volume nor did it block the colchicines-induced decrease in volume. One the other hand, SITS (4’acetamido, 4-isothiocyano 2,2’ disulfonic acid stilbene), an inhibitor of anion transport, inhibited the effects of colchicines, thus suggesting a role for an anion transport system in cell volume regulation. Because colchicine is known to activate adenylate cyclase in several systems and because cell shape changes are often induced by hormones that elevate cyclic AMP, we also examined the effects of cyclic AMP on cell volume. Agents that act to increase syclic AMP (cholera toxin, which activates adenylate cyclase; IBMX, and inhibitor of phosphodiesterase; and dibutyryl cyclic AMP) all caused a volume decrease comparable to that of colchicine. To define the effective metabolic pathway, we studied two mutants of J774.2, one deficient in adenylate cyclase and the other exhibiting markedly reduced activity of cyclic AMP-dependent protein kinase. Cholera toxin did not produce a volume change in either mutant. Cyclic AMP produced a decrease in the cyclase-deficient line comparable to that in wild type, but did not cause a volume change in the kinase- deficient line. This analysis established separate roles for cyclic AMP and colchicine. The volume decrease induced by cyclic AMP requires the action of a cyclic AMP-dependent protein kinase. Colchicine, on the other hand, induced a comparable volume change in both mutants and wild type, and thus does not require the kinase.     

Membrane behavior of exocytic vesicles: II in fate of the trichocyst membranes in paramecium after induced trichocyst discharge

A specific exocytic process, the discharge of spindle trichocysts of paramecium caudatum was examined by means of the electron microscope. This exocytosis is induced by an electric shock simultaneously in nearly all of the trichocysts (ca. 6,000-8,0000 of a single cell. Single paramecia were subjected to the shock and then fixed at defined times after the shock so that the temporal sequence of the pattern of changes of the trichocyst membranes after exocytosis could be studied. The trichocyst vacuoles fuse with the plasma membrane only for that length of time required for expulsion to take place. After exocytosis, the membrane of the vacuole does not become incorporated into the plasma membrane; rather, the collapsed vacuole is pinched off and breaks up within the cytoplasm. The membrane vesiculates into small units which can no longer be distinguished from vesicles of the same dimensions that exist normally within the cell's cytoplasm. the entire process is completed within 5-10 min. These results differ from the incorporation of mucocyst membranes into the plasma membrane as proposed for tetrahymena.     

metaBIT,an integrative and automated metagenomic pipeline for analysing microbial profiles from high‐throughput sequencing shotgun data

Micro‐organisms account for most of the Earth's biodiversity and yet remain largely unknown. The complexity and diversity of microbial communities present in clinical and environmental samples can now be robustly investigated in record times and prices thanks to recent advances in high‐throughput DNA sequencing (HTS). Here, we develop metaBIT, an open‐source computational pipeline automatizing routine microbial profiling of shotgun HTS data. Customizable by the user at different stringency levels, it performs robust taxonomy‐based assignment and relative abundance calculation of microbial taxa, as well as cross‐sample statistical analyses of microbial diversity distributions. We demonstrate the versatility of metaBIT within a range of published HTS data sets sampled from the environment (soil and seawater) and the human body (skin and gut), but also from archaeological specimens. We present the diversity of outputs provided by the pipeline for the visualization of microbial profiles (barplots, heatmaps) and for their characterization and comparison (diversity indices, hierarchical clustering and principal coordinates analyses). We show that metaBIT allows an automatic, fast and user‐friendly profiling of the microbial DNA present in HTS shotgun data sets. The applications of metaBIT are vast, from monitoring of laboratory errors and contaminations, to the reconstruction of past and present microbiota, and the detection of candidate species, including pathogens.     

Eight new microsatellite markers in Atlantic cod (Gadus morhua L.) derived from an enriched genomic library

One hundred and fifty random clones from an enriched genomic library of Atlantic cod were sequenced. Primer pairs were designed for 15 microsatellites containing perfect di‐, tri‐, tetra‐ and hexanucleotide repeats and characterized in 96 unrelated fish. Eight markers were successfully amplified, with the number of alleles ranging from two to nine per locus and observed heterozygosity ranging from 0.341 to 0.977. Loci Gmo‐G13 and Gmo‐G14 had a significant excess of homozygotes. All loci conformed to the Hardy–Weinberg equilibrium. Genetic linkage disequilibrium analysis between all pairs of the loci showed no significant departure from the null hypothesis between any of the loci.     

Chk2 is a tumor suppressor that regulates apoptosis in both an ataxia telangiectasia mutated (ATM)-dependent and an ATM-independent manner

In response to ionizing radiation (IR), the tumor suppressor p53 is stabilized and promotes either cell cycle arrest or apoptosis. Chk2 activated by IR contributes to this stabilization, possibly by direct phosphorylation. Like p53, Chk2 is mutated in patients with Li-Fraumeni syndrome. Since the ataxia telangiectasia mutated (ATM) gene is required for IR-induced activation of Chk2, it has been assumed that ATM and Chk2 act in a linear pathway leading to p53 activation. To clarify the role of Chk2 in tumorigenesis, we generated gene-targeted Chk2-deficient mice. Unlike ATM(-/-) and p53(-/-) mice, Chk2(-/-) mice do not spontaneously develop tumors, although Chk2 does suppress 7,12-dimethylbenzanthracene-induced skin tumors. Tissues from Chk2(-/-) mice, including those from the thymus, central nervous system, fibroblasts, epidermis, and hair follicles, show significant defects in IR-induced apoptosis or impaired G(1)/S arrest. Quantitative comparison of the G(1)/S checkpoint, apoptosis, and expression of p53 proteins in Chk2(-/-) versus ATM(-/-) thymocytes suggested that Chk2 can regulate p53-dependent apoptosis in an ATM-independent manner. IR-induced apoptosis was restored in Chk2(-/-) thymocytes by reintroduction of the wild-type Chk2 gene but not by a Chk2 gene in which the sites phosphorylated by ATM and ataxia telangiectasia and rad3(+) related (ATR) were mutated to alanine. ATR may thus selectively contribute to p53-mediated apoptosis. These data indicate that distinct pathways regulate the activation of p53 leading to cell cycle arrest or apoptosis.     

Metastatic sweat gland adenocarcinoma: A clinico-pathological dilemma

Background  

Sweat gland adenocarcinoma is a rare malignancy with high metastatic potential seen more commonly in later years of life. Scalp is the most common site of occurrence and it usually spreads to lymph nodes. Liver, lung and bones are the distant sites of metastasis with fatal results. The differentiation between apocrine and eccrine metastatic sweat gland carcinoma is often difficult. The criteria's are inadequate to be of any practical utility.     

Molecular characterization of germline NF2 gene rearrangements

Neurofibromatosis type 2 (NF2) is an autosomal dominant disease that causes a predisposition to nervous system tumors. Deleterious point mutations have been found in about 55% of NF2 patients, and large genomic deletions account for approximately 33% of NF2 gene alterations. The majority of these deletions are larger than 50 kb, with a breakpoint usually lying outside the NF2 gene. We identified two cases of intragenic deletion with loss of 1.5 and 40 kb, respectively. In both cases, one boundary of the deletion was located in or at the proximity of an SVA sequence in NF2 intron 4. No sequence identity longer than 5 bases and no signal of specific recombination have been evidenced on either side of the deletion breakpoints. These observations are compatible with a nonhomologous recombination being responsible for the genomic deletions. In a third case, a paracentric inversion of chromosome 22 was found. This chromosomal rearrangement breaks the NF2 gene in two parts and carries the first NF2 exon in a juxta-centromeric position. The variability in position of the deletions and the observation of a new chromosomal rearrangement in the NF2 gene underscore the importance of FISH analysis in the molecular diagnosis of NF2.