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The facultative heterochromatic X chromosome in leptotene spermatocytes of the grasshopper Eyprepocnemis plorans showed marked hypoacetylation for lysine 9 in the H3 histone (H3-K9) with no sign of histone H2AX phosphorylation. Since H3-K9 hypoacetylation precedes the meiotic appearance of phosphorylated H2AX (γ-H2AX), which marks the beginning of recombinational DNA double-strand breaks (DSBs), it seems that meiotic sex-chromosome inactivation (MSCI) in this grasshopper occurs prior to the beginning of recombination and hence synapsis (which in this species begins later than recombination). In addition, all constitutively heterochromatic chromosome regions harbouring a 180-bp tandem-repeat DNA and rDNA (B chromosomes and pericentromeric regions of A chromosomes) were H3-K9 hypoacetylated at early leptotene even though they will synapse at subsequent stages. This also suggests that meiotic silencing in this grasshopper might be independent of synapsis. The H3-K9 hypoacetylated state of facultative and constitutive heterochromatin persisted during subsequent meiotic stages and was even apparent in round spermatids. Finally, the fact that B chromosomes are differentially hypoacetylated in testis and embryo interphase cells suggests that they might be silenced early in development and remain this way for most (or all) life-cycle stages. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

It is widely accepted that the H2AX histone in its phosphorylated form (γ-H2AX) is related to the repair of DNA double-strand breaks (DSBs). In several organisms, γ-H2AX presence has been demonstrated in meiotic processes such as recombination and sex chromosome inactivation during prophase I (from leptotene to pachytene). To test whether γ-H2AX is present beyond pachytene, we have analysed the complete sequence of changes in H2AX phosphorylation during meiosis in grasshopper, a model organism for meiotic studies at the cytological level. We show the presence of phosphorylated H2AX during most of meiosis, with the exception only of diplotene and the end of each meiotic division. During the first meiotic division, γ-H2AX is associated with i) recombination, as deduced from its presence in leptotene-zygotene over all chromosome length, ii) X chromosome inactivation, since at pachytene γ-H2AX is present in the X chromosome only, and iii) chromosome segregation, as deduced from γ-H2AX presence in centromere regions at first metaphase-anaphase. During second meiotic division, γ-H2AX was very abundant at most chromosome lengths from metaphase to telophase, suggesting its possible association with the maintenance of chromosome condensation and segregation. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objectives: Polymorphisms of the CC chemokine receptor 6 (CCR6) gene have been recently reported to be associated with a number of autoimmune diseases. We aimed to investigate the possible influence of CCR6 rs3093024 gene variant in the susceptibility to and clinical expression of GCA., Methods: The CCR6 polymorphism rs3093024 was genotyped in a total of 463 Spanish patients diagnosed with biopsy-proven GCA and 920 healthy controls using a TaqMan® allelic discrimination assay. PLINK software was used for the statistical analyses., Results: No significant association between this CCR6 variant and GCA was observed (p=0.42, OR=0.94, CI95% 0.79-1.10). Similarly, when patients were stratified according to the specific clinical features of GCA such as polymyalgia rheumatica, visual ischaemic manifestations or irreversible occlusive disease, no statistical significant difference was detected either between the case subgroups and the control set or between GCA patients with and without the specific features of the disease., Conclusions: Our results suggest that the CCR6 rs3093024 polymorphism may not play a relevant role in the GCA pathophysiology.

Cell migration is one of the earliest events required for development of the testis. Migration occurs only in XY gonads downstream of Sry expression and is required for the subsequent epithelialization of testis cords. Using organ culture experiments and tissue recombination, we and others speculated that peritubular myoid (PTM) cells were among the migratory cells and were likely the cell type required for cord formation. However, because no unique marker was found for PTM cells, their positive identification during or after migration remained unclear. alpha-Smooth Muscle Actin (alphaSma; approved gene symbol Acta2), a classic marker of adult PTM cells,is expressed broadly in testis interstitial cells at E12.5, and becomes highly enriched in PTM cells by E15.5-16.5. We used a novel transgenic line expressingEYFP under the control of an alphaSma promoter to determine whether alphaSma-EYFP positive cellsmigrate into the gonad. Surprisingly, mesonephroi expressing alphaSma-EYFP do not contribute any EYFP positive cells to XY gonads when used as donors in recombination cultures. These results indicate that alphaSma-EYFP cells do not migrate into the gonad during the critical window of sex determination and cannot be the migrating cell type required for testis cord formation. Our results suggest that PTM cells, and most other interstitial lineages, with the exception of endothelial cells, are induced within the gonad. These experiments suggest that endothelial cells are the migrating cell type required for epithelialization of testis cords., (Copyright 2008 S. Karger AG, Basel.)

In mammals, germ cells are important both during development and for the function of female gonads, whereas male gonads may develop in the absence of germ cells. The gonads of female moles (genus Talpa) develop according to a testis-like pattern which results in the formation of ovotestes. In this paper, we studied the expression pattern of several pre-meiotic and meiotic germ cell markers, in order to establish the precise time of meiosis onset in the mole species T. occidentalis, and to investigate the location and possible role of germ cells in ovotestis organogenesis. Our results evidenced that: (1) the asymmetrical distribution of primordial germ cells, which concentrate in the cortex of the XX gonad, is brought about by germ cell depletion from the medulla between the s5a and s5b stages, (2) XX germ cells enter meiosis postnatally, which is quite exceptional among eutherian mammals, and (3) XX but not XY germ cells of moles express DMRT1 during premeiotic stages of development, an expression pattern not described previously in vertebrates., ((c) 2007 S. Karger AG, Basel)