Babesia microti are hemoprotozoan parasites of the phylum apicomplexa. Entire coding core of the three chromosomes have been assembled for an overall size of 6.4 Mbp. Analysis of orthologues from energy, glycosylphosphatidylinositol biosynthesis and DNA repair pathways revealed mix characteristic of Babesia and Theileria in the B. microti genome.

The understanding of androgen-regulated gene expression requires a cell cultures system that mimics the functions of cells in vivo. In the present paper we have examined a vas deferens epithelial cell subculture system. Cultured vas deferens epithelial cells have been shown to exhibit polarized properties characteristic of functioning epithelia and to display a high level of androgen receptors. Incubation of cells with androgen caused a decrease in cellular androgen receptor mRNA that was time-dependent. Total suppression was observed after 24h of exposure to androgen. By contrast, incubation of vas deferens epithelial cells with androgen resulted in a threefold increase in the cellular content of androgen receptor protein, as assayed by ligand binding. In response to androgens, vas deferens epithelial cells expressed mouse vas deferens protein mRNA (MVDP mRNA). Maximum expression of the MVDP gene, at both mRNA and protein levels, was observed after 24h of androgen induction. DEAE-dextran transfection conditions were defined using the MMTV-CAT gene in vas deferens epithelial cells in a dose- and time-dependent manner. No induction was seen when fragments of the MVDP promoter region were cloned directly in front of the CAT gene and transiently transfected into vas deferens epithelial cells. It was found that cotransfection of cells with MVDP-CAT gene and transfection of cells with MVDP-CAT constructs and with an androgen receptor expression vector resulted in a small but consistent androgen-dependent increase in reporter gene activity. Transiently transfected vas deferens epithelial cells are a suitable model with which to study the effect of androgen on gene regulatory elements.

Mouse vas deferens protein (MVDP), a member of the aldo-keto reductase superfamily, is exclusively produced in the vas deferens. To better understand androgen-regulated MVDP gene expression we have used RNA hybridization to study the effects of androgens on the steady-state levels of MVDP mRNA in vas deferens epithelial cell subcultures. Northern blot analysis revealed that these cells only express MVDP mRNA in the presence of androgens. There was a close relationship between MVDP mRNA levels and dihydrotestosterone concentrations. MVDP mRNA is induced over a period of 24h and maximal induction is about 25-fold. Treatment of cells with cycloheximide completely abolished the observed androgen effect suggesting that the induction of the MVDP gene by androgens depends on continuous protein synthesis. Transient transfection of vas deferens epithelial cells with MMTV-CAT vector showed that these cells contained functional androgen receptors and that they are a suitable system to study androgen effect on MVDP gene regulatory elements.

The kinetics and signal transduction of inositol phosphate production were studied after a 20% stretch of neonatal rat cardiomyocytes in culture. Inositol trisphosphate (IP3) production was increased by 41% above control after 10-20s of cellular stretch but returned to control after 120s of stretch. The increase in IP3 was potentiated in high K+ medium and was inhibited by pertussis toxin, suggesting the existence of a pertussis toxin-sensitive G protein in signal transduction. Ion-pair HPLC analysis of cell extracts stretched for 20s showed an increase in both IP3 isomers, mostly 1, 4, 5-IP3 (+66%) with a weak increase in IP4 (+10%), whereas 120s stretch induced an increase in IP4 (+26% above control) associated with a decrease of 1, 4, 5-IP3 isomer as compared with 20s stretch. It is concluded that the progressive increase in IP4 production associated with an early rise in IP3 after stretching myocardial cells may be a factor inducing the length-dependent activation of cardiac muscle through a modulation of intracellular free calcium concentration.

Exocytotic processes play a major role in the hormonal control of water permeability in the amphibian urinary bladder. Different treatments such as antidiuretic hormone (ADH) stimulation, incubation with phorbol ester or mild detergent and mechanical stretch of the bladder, consistently induce a liberation of two major polypeptides of 76 and 14 kDa molecular mass into the luminal medium. Each of these polypeptides represents 3 to 5% of the total protein of epithelial cell homogenates and 20 to 50% of the released material. Proportions of released 76 kDa polypeptide in urinary bladders of toads (Bufo marinus) and frogs (Rana esculenta) were similar but, in the frog extracts, two bands ("doublet") were resolved at the level of 76 kDa. In high performance liquid chromatography (HPLC), using gel filtration and ion exchange chromatography, the frog 76 kDa protein was resolved into two polypeptides of 80,000 to 100,000 and 60,000 to 80,000 daltons while the 14 kDa protein included two polypeptides, each with a molecular mass of approximately 14,000 daltons. Isoelectric focusing of the material released during a mechanical stretch of the tissue ("stretch extract") or of isolated purified proteins from the frog urinary bladder showed that the 14 kDa polypeptides were resolved in two major groups of polypeptides, one in the range of pH 7.4 to 7.8, the other at pH 5.6. The lower band of the 76 kDa doublet also comprised some diffuse bands (5.0 less than pI less than 5.2) while the other polypeptide of the doublet presented a sharp band at pH 6.2.(ABSTRACT TRUNCATED AT 250 WORDS)

Several experimental conditions such as antidiuretic hormone (ADH) challenge, apical treatment with phorbol myristate acetate (PMA), and mechanical stretching of the tissue are known to increase the insertion of intramembrane particle aggregates and/or granule exocytosis at the apical border of epithelial cells of amphibian urinary bladders. A constant release of 2 peptides of 76 and 14 kDa apparent molecular mass, respectively, was associated with these treatments. The localization of these 2 polypeptides was assessed by immunofluorescence and electron microscopy immunocytochemistry using fluorescent, peroxidase, and colloidal gold probes. The 76 kDa polypeptide appeared to be associated with the cell coat and with the granule content which is released at the apical cell surface. The 14 kDa peptide was also found in the cell coat, and postembedding immunocytochemistry indicates its presence in cytoplasmic subapical vesicles (aggrephores and/or granules). The migration of these 76 and 14 kDa polypeptides in SDS-polyacrylamide gel electrophoresis was modified neither by a treatment at 90 degrees C, nor by the presence or absence of calcium in the medium. Treatment with EGTA did not modify the fluorescence emission of the two peptides and, consequently, they are probably not among the major calcium binding proteins. The addition to the mucosal medium of the stretch extract or of antibodies raised against the 76 and 14 kDa peptides did not modify ADH-induced water permeability. However, a significant decrease of the hydrosmotic response to ADH occurred in subsequent stimulation-washout cycles when the anti-14 kDa peptide antiserum was applied to the mucosal bath. When the bladders were incubated with a stretch extract, we observed a slight alteration of the short-circuit current (Isc), an increase of the basal Na+ transport, and a decrease of the maximal Isc in response to ADH. The 76 kDa protein, released in the apical medium, could play a protective role in the cellular plasma membrane and could participate in the formation of the thick cell coat lining the apical membrane of the granular cells. The 14 kDa protein might be one of the proteins associated with the aggregates, but further studies will be necessary to clarify its exact role in the ADH-induced permeability modifications observed in amphibian urinary bladders.