In CK2 inactivated cells the cyclin dependent kinase inhibitor Sic1 is involved in cell-cycle arrest before the onset of S phase

Protein kinase CK2 is a heterotetramer composed of two catalytic and two regulatory subunits. In Saccharomyces cerevisiae the catalytic subunits (alpha and alpha') are encoded by the CKA1, CKA2 genes. cka1Deltacka2(ts) mutants arrest cell cycle in both G1 and G2/M at 37 degrees C. Hence, it has been proposed that CK2 plays an important role in cell-cycle progression and several cell-cycle proteins have been reported to be CK2 substrates. We have previously shown that Sic1, the inhibitor of Clb5-Cdc28 complexes required for the G1/S transition, is a physiologically relevant CK2 substrate. Here we show that CK2 inactivation up-regulates Sic1 level resulting in severe down-regulation of Clb5-Cdc28 kinase activity. Concurrent inactivation of Sic1 and CK2 leads to accumulation of cells with a post-synthetic DNA content and short/elongated spindles, typical of cells arrested in mitosis. These findings indicate that Sic1 plays a major role during G1 arrest of CK2-inactivated cells.     

Histological and immunohistological aspects of the ovarian cycle of the algerian wild sand rat, Psammomys obesus Cretzschmar, 1828

The sand rat, Psammomys obesus, is largely used as a model for studying several metabolic disorders. In order to perform breeding laboratory conditions, the reproductive function of this species was investigated. Using histological and immunohistochemical techniques, several aspects of the ovaries were studied throughout the sexual cycle. During the ovarian cycle, the different stages of folliculogenesis, from primordial to Graafian follicle, have been shown; the differentiation of both granulosa and theca cells, the formation of the antrum, cumulus oophorus and corona radiate were described. Broken follicles and corpora lutea have been observed, confirming a spontaneous ovulation in isolated females. Steroid activities were analysed using immunohistochemical techniques. Estrogen, androgen and progesterone hormones were visualized in the different compartments of the ovary.     

Connexin 43 confers resistance to hydrogen peroxide-mediated apoptosis

The current study aimed to understand the anti-apoptotic effect of overexpressed gap junction forming protein connexin (Cx) 43 in C6 glioma cells. C6 cells exposed to hydrogen peroxide (H2O2) or staurosporine demonstrated morphological and biochemical changes consistent with apoptosis, whereas C6 cells expressing Cx43 demonstrated relative resistance to H2O2, but not to staurosporine. This selective protection against H2O2 was due to inhibition of caspase-3 activation in Cx43 expressing cells. siRNA knockdown experiments in rat primary astrocytes confirmed the presence of endogenous Cx43-mediated anti-apoptotic effect. Cx43 interacts with the upstream apoptosis signal-regulating kinase 1 known to mediate H2O2-induced apoptosis providing a possible mechanism for protection. These findings provided new evidence for regulation of the mitogen activated protein kinase pathway and apoptosis by Cx43 implicating this protein in intracellular signaling beyond its role as a gap junction forming protein on the plasma membrane.     

Studies on stomatal function, epicuticular wax and stem-root transition region of polyethylene glycol-treated and nontreatedin vitro grape plantlets

Summary Scanning electron microscopy, light microscopy, and gravimetric analysis was used to evaluate stomatal function, epicuticular wax, and the stem-root transition region of grape (Vitis sp. ‘Valiant’) plantlets grownin vitro, polyethylene glycoltreatedin vitro, and greenhouse-grown plants. Scanning electron microscopic studies of leaf surfaces ofin vitro-grown plants showed widely open stomata as compared to leaf stomata of polyethylene glycol-treatedin vitro-cultured and greenhouse-grown plants. Ultrastructurally, leaf epicuticular wax ofin vitro plants was less dense than in their polyethylene-treated and greenhouse counterparts. Quantitatively,in vitro-grown plants had reduced epicuticular was as compared to polyethylene glycol-treated and greenhouse-grown plants. Light microscopic studies showed no obvious differences in the vascular connections in the stem-root transition region ofin vitro-cultured, polyethylene glycol-treatedin vitro-cultured, and greenhouse-grown plants. It is therefore likely that the rapid wilting and desiccation observed after transplantingin vitro grape plantlets is due to their defective stomatal function and reduced epicuticular wax and may not be due to poor water transport associated with vascular connection.     

Neospora caninum is associated with abortion in Algerian cattle

Neospora caninum is a major cause of abortion in cattle worldwide. However, little information is available for Algeria. Accordingly, 799 cattle from 87 farms in the north and northeast of Algeria were enrolled in a seroepidemiological survey. An indirect fluorescence antibody test (IFAT) revealed a seroprevalence of 19.6%. The animals were divided into 3 groups according to their breed: imported European cattle, local breeds, and crossed animals (European × local). Seroprevalences were 16.0%, 34.3%, and 18.6% in groups 1, 2, and 3, respectively. A case control study was performed to investigate the link between global seropositivity to N. caninum and abortion risk in those cattle farms. There was a significant (P < 0.01) association between the seroprevalence against N. caninum and the occurrence of abortion in those farms (odds ratio [OR] = 12.03). This was also observed at the individual level (OR = 2.79). The analysis of results according to the breed revealed a significant association between seroprevalence and abortion in groups 1 and 3, but not for group 2, despite the fact that the highest seroprevalence was observed in group 2. Cerebral tissues from 5 aborted fetuses were available for histology and polymerase chain reaction (PCR). One sample was found positive both by histology and by PCR, 2 samples were positive by PCR only, and 2 samples were negative in both tests.     

A Single Amino Acid Change in the Hemagglutinin Protein of Measles Virus Determines Its Ability To Bind CD46 and Reveals Another Receptor on Marmoset B Cells

This paper provides evidence for a measles virus receptor other than CD46 on transformed marmoset and human B cells. We first showed that most tissues of marmosets are missing the SCR1 domain of CD46, which is essential for the binding of Edmonston measles virus, a laboratory strain that has been propagated in Vero monkey kidney cells. In spite of this deletion, the common marmoset was shown to be susceptible to infections by wild-type isolates of measles virus, although they did not support Edmonston measles virus production. As one would expect from these results, measles virus could not be propagated in owl monkey or marmoset kidney cell lines, but surprisingly, both a wild-type isolate (Montefiore 89) and the Edmonston laboratory strain of measles virus grew efficiently in B95-8 marmoset B cells. In addition, antibodies directed against CD46 had no effect on wild-type infections of marmoset B cells and only partially inhibited the replication of the Edmonston laboratory strain in the same cells. A direct binding assay with insect cells expressing the hemagglutinin (H) proteins of either the Edmonston or Montefiore 89 measles virus strains was used to probe the receptors on these B cells. Insect cells expressing Edmonston H but not the wild-type H bound to rodent cells with CD46 on their surface. On the other hand, both the Montefiore 89 H and Edmonston H proteins adhered to marmoset and human B cells. Most wild-type H proteins have asparagine residues at position 481 and can be converted to a CD46-binding phenotype by replacement of the residue with tyrosine. Similarly, the Edmonston H protein did not bind CD46 when its Tyr481 was converted to asparagine. However, this mutation did not affect the ability of Edmonston H to bind marmoset and human B cells. The preceding results provide evidence, through the use of a direct binding assay, that a second receptor for measles virus is present on primate B cells.