Biomedical subjects

S Shalom

Publications and source records attributed to S Shalom.

6 recordsLinked to original sources

PubMed1999

Tlk, a novel evolutionarily conserved murine serine threonine kinase, encodes multiple testis transcripts.

Hypothesizing that genes important in meiotic processes in mammals might have evolutionarily conserved counterparts in lower organisms, we used the yeast IME2 meiotic gene (serine threonine kinase) as a probe for screening a mouse testis cDNA library. This screening resulted in identification of a novel putative serine threonine kinase. Although it did not exhibit significant homology to IME2, it did show significant sequence homology to the Tousled kinase in Arabidopsis. Tousled is associated with various differentiative processes including differentiation of the reproductive organs. The new murine gene was designated accordingly Tlk (Tousled like kinase). Tousled like kinase sequences have been reported to occur in C. elegans and in the human. Positive hybridization signals obtained in zooblot analysis suggest evolutionary conservation of Tlk throughout the phylogenetic ladder. Four distinct Tlk transcripts were detected in mouse testis, at least one of which is testis-specific. Northern and in situ hybridization analyses revealed that in normal testis, Tlk is expressed predominantly in pachytene spermatocytes and in round spermatids. Transcripts differ from one another in their 3' untranslated region, resulting from use of different polyadenylation sites, and in the length of their 5' region. Within the coding region, three of the putative peptides share the kinase and C-terminal domains but differ in their N-terminal domain, suggesting that the latter may be involved in the regulation of Tlk's function. We conclude that although Tlk might have an essential role in all tissues, these kinases are likely to take part in the complex array of phosphorylations involved in regulating spermatogenesis.

Aging↗

PubMed1999

Two alternatively spliced Meig1 messenger RNA species are differentially expressed in the somatic and in the germ-cell compartments of the testis.

Previous studies regarding the transcriptional pattern of the murine Meig1 gene (formally designated meg1) suggested that its transcription is restricted to germ cells at the first meiotic prophase, in both primary spermatocytes and primary oocytes. However, protein analysis revealed that certain forms of the MEIG1 protein exist in testes of early postnatal pups at stages that have no germ cells in the testis, excluding very few primitive type A spermatogonia cells. This suggested that MEIG1 expression is not confined to germ cells. In this study, we show that testicular somatic cells do, indeed, express MEIG1. This is especially evident in Leydig cells, where this protein is highly abundant. We also demonstrate that alternatively spliced mRNAs of Meig1 are differentially transcribed in the germ cell and the somatic compartments of the testis. There is a very low level of somatic transcript, whether labile or transcriptionally regulated, in contrast to the abundant MEIG1 protein in the somatic cells. This implies that the somatic transcript is very efficiently translated and reconfirms that protein levels do not necessarily reflect transcript abundancy. Structural features of the Meig1 transcript that would be expected to inhibit translation are discussed in light of the efficient translation of this RNA species.

Alternative Splicing↗

PubMed1998

The human Pim-2 proto-oncogene and its testicular expression.

In this study we describe the cloning of a human gene, encoding a protein that shares 90% identity and 93% similarity at the primary structure level, with the mouse Pim-2 gene. The gene was designated hPim-2. Structural features suggest that like the mouse Pim-2, hPim-2 is also a serine threonine kinase. At the RNA level, two hPim-2 transcripts were identified. The first, 2.2 kb, is highly expressed in hematopoietic tissues and in leukemic and lymphoma cell lines (K-562, HL-60 and RAJI). It also shows considerable high levels in testis, small intestine, colon and human colorectal adenocarcinoma cells (SW480). A second transcript, 5.0 kb in size, could be detected only in spleen, thymus, small intestine and colon and in the K-562 and RAJI cell lines. In situ hybridization analysis of biopsies taken from testes of men with complete or partial spermatogenesis revealed that the gene is expressed in primary spermatocytes. In the absence of germ cells, signal could be detected over specific cells in the well developed interstitial region. These results suggest a role for hPim-2 in proliferating cells as well as during meiosis. A possible connection between hPim-2 and apoptosis is discussed.

Adenocarcinoma↗

PubMed1997

An optical submicrometer calcium sensor with conductance sensing capability.

The identification of chemical species and the measurement of their concentrations with high (submicrometer) spatial resolution are of considerable importance in cell biology. In this article we report the first successful development of a > or = 0.1-micron Ca2+ sensor based on a pulled micropipet, filled with a conducting porous sol-gel glass which was doped with the fluorescent calcium green 1 Ca2+ indicator. Such sensors are potentially capable of measuring Ca2+ concentrations as low as 10(-8) M, in confined volumes, with a three-dimensional resolution which exceeds approximately 0.1 micron. A major advantage of the sensor is its capability to be integrated into a multifunctional probe which will measure chemical analyte concentrations and ion conductance.

Animals↗

PubMed1997

A switch in the phosphorylation state of the dimeric form of the Meg1 protein correlates with progression through meiosis in the mouse.

meg1 is a murine gene that encodes for a 0.75-kb transcript that in mature male mice is expressed exclusively in the testis. This transcript starts to accumulate in early stages of the first meiotic prophase and reaches a peak in pachytene spermatocytes. In females, meg1 transcripts are detectable only in ovaries of embryos with oocytes that have reached the prophase stage of the first meiotic division. No meg1 transcripts can be detected in adult ovaries. meg1 is, therefore, assumed to be involved with meiotic processes. In this study, specific polyclonal antibodies were raised against the Meg1 protein and were used to demonstrate that this protein is indeed specific to the testis. Western blot analysis of immunoprecipitated Meg1 protein revealed multiple bands (in the range of M(r) 12,000-18,000), some of which where recognized by anti-phosphotyrosine antibodies, suggesting that in vivo, Meg1 appears in multiple phosphorylated forms. Western analysis of purified M(r) 15,000 recombinant Meg1 protein, under nonreducing conditions, revealed an apparent M(r) 31,000 band, suggesting that Meg1 can form a homodimer via S-S bonds. Analysis of Meg1 from postnatal testes at different developmental stages revealed that in addition to the multiple monomeric forms of Meg1, two dimeric forms of about M(r) 31,000 and M(r) 32,000 were consistently detected. A developmentally regulated switch in the relative predominance of these two dimeric forms was apparent. The M(r) 31,000 form, which is tyrosine phosphorylated, becomes the predominant form once the cells enter meiosis. These results suggest that dimerization and phosphorylation/dephosphorylation reactions might regulate the function of Meg1 during meiosis.

Animals↗

PubMed1994

[Emotional reactions of psychiatric staff to violent patients].

Approximately 10% of psychiatric patients are violent and their violence is often directed towards the treating staff. Up to half of all psychiatrists have been physically assaulted at some time during their careers. Emotional reactions of the psychiatric staff to assault by patients vary, and include fear, anger and helplessness. Psychological defense mechanisms employed include projection, denial and isolation. For the staff, these reactions are a source of distress and a cause of burn-out. Anger can lead to nontherapeutic interventions such as counter-aggression.

Defense Mechanisms↗