An analysis of maleless and histone H4 acetylation in Drosophila melanogaster spermatogenesis

Abstract

Maleless (mle) is essential in Drosophila melanogaster males both in somatic cells and in germ cells. In somatic cells mle is necessary for X-chromosome dosage compensation. The role of mle in the germline is unknown. We have analyzed the expression pattern and localization of MLE, the other MSLs and acetylated isoforms of histone H4 in male germ cells to address whether dosage compensation and/or X inactivation occur in the Drosophila germline. We observed that MLE is the only MSL expressed in the male germ cells and it is not localized to the X chromosome. We conclude that in the germline mle is not involved in chromosomal dosage compensation but may be involved in post-transcriptional gene regulation. We also observed that the acetylation pattern of histone H4 is very dynamic during spermatogenesis. While the pattern is not compatible with dosage compensation or X inactivation, it is consistent with all premeiotic chromosomes being in an active configuration that is replaced in post-meiotic stages with an inactive chromatin constitution.

Gene Expression Analysis of the Function of the Male-Specific Lethal Complex in Drosophila

“…Analysis of global patterns of gene expression in the 367-375. germline of Drosophila has indicated a generalized pres- (Rastelli and Kuroda 1998). This study and factor in neurospheres derived from fetuses with Down's synour previous studies (Hiebert and Birchler 1994; drome: a gene expression study.…”

“…Because compensation is present in the mof mutants, but not tylation become distributed throughout the genome (Bhadra et al 1999). In female genotypes that allow in the double-mutant mof ; mle genotype, these results suggest that histone acetylation or the MSL complex expression of MSL2 and thus sequestration of the com- Gu et al 2000;Kageyama et al 2001). It was previously determined that such binding is not detectable in the mle/mle male genotype (Bhadra et al 2000).…”

“…(Meller and Rattner 2002). Second, in the germline there is no MSL complex and the histone acetylation This relationship helps explain the need for an override system of the high levels of acetylation on the noris distributed throughout the nucleus (Rastelli and Kuroda 1998). Thus, male nuclei lacking the MSL commal male X.…”

Paucity of Genes on the Drosophila X Chromosome Showing Male-Biased Expression

“…Our analysis might be identifying those genes. Second, the X chromosomes of Drosophila and other animals become precociously condensed and inactivated in spermatocytes (11)(12)(13)(14). If X-chromosome inactivation occurs early enough to alter steady-state transcript levels in spermatocytes, then this effect could explain the underrepresentation we observe.…”

Male genes: X‐pelled or X‐cluded?

“…Although H4 acetylation occurs in the germline, it is not restricted to the X chromosome. (19) X-inactivation A related hypothesis specifically addresses the deficit of X-linked spermatogenesis genes. If the X chromosome is inactivated earlier in spermatogenesis than the autosomes, as occurs in C. elegans, (20) male germline-specific genes on the X chromosome would have no effect during the later stages of male gametogenesis.…”