RADHA - a new male germ line-specific chromosomal protein of Drosophila

A unique member of the mouse HSP70 gene family has been isolated and characterized with respect to its DNA sequence organization and expression. The gene contains extensive similarity to a heat shock-inducible HSP70 gene within the coding region but diverges in both 3' and 5' nontranslated regions. The gene does not yield transcripts in response to heat shock in mouse L cells. Rather, the gene appears to be activated uniquely in the male germ line. Analysis of RNA from different developmental stages and from enriched populations of spermatogenic cells revealed that this gene is expressed during the prophase stage of meiosis. A transcript different in size from the major heat-inducible mouse transcripts is most abundant in meiotic prophase spermatocytes and decreases in abundance in postmeiotic stages of spermatogenesis. This pattern of expression is distinct from that observed for another member of this gene family, which was previously shown to be expressed abundantly in postmeiotic germ cells. These observations suggest that specific HSP70 gene family members play distinct roles in the differentiation of the germ cell lineage in mammals.

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Developmental expression of c-kit, a proto-oncogene encoded by the W locus

Development ◽

10.1242/dev.109.4.911 ◽

1990 ◽

Vol 109 (4) ◽

pp. 911-923 ◽

Cited By ~ 16

Author(s):

A. Orr-Urtreger ◽

A. Avivi ◽

Y. Zimmer ◽

D. Givol ◽

Y. Yarden ◽

...

Keyword(s):

Germ Cells ◽

Receptor Tyrosine Kinase ◽

Germ Line ◽

Primordial Germ Cells ◽

Mouse Embryos ◽

Developmental Expression ◽

Male Germ Line ◽

Polypeptide Growth Factors ◽

Adult Ovary

Developmental expression of the c-kit proto-oncogene, a receptor tyrosine kinase encoded by the W locus, was investigated by in situ hybridization in normal mouse embryos. Early after implantation transcripts were detectable only in the maternal placenta (6 1/2-7 1/2 days p.c.). Subsequently (8 1/2 days p.c.) numerous ectodermal (neural tube, sensory placodes) and endodermal (embryonic gut) derivatives expressed c-kit. Later transcripts were detected also in the blood islands of the yolk sac and in the embryonic liver, the main sites of embryonic hemopoiesis. Around midgestation, transcripts accumulated in the branchial pouches and also in primordial germ cells of the genital ridges. This complex pattern of expression remained characteristic also later in gestation, when c-kit was expressed in highly differentiated structures of the craniofacial area, in presumptive melanoblasts and in the CNS. In the adult ovary, maternal c-kit transcripts were detected. They were present in the oocytes of both immature and mature ovarian follicles, but not in the male germ line, where c-kit expression may be down regulated. Thus, c-kit activity is complex and appears in multiple tissues including those that also display defects in mutations at the W locus where c-kit is encoded. Correlation between W phenotypes and c-kit expression, as well as the regulation of the complex and multiple expression of polypeptide growth factors and receptors, is discussed.

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The heterochromatin-associated protein HP-1 is an essential protein in Drosophila with dosage-dependent effects on position-effect variegation.

Genetics ◽

10.1093/genetics/131.2.345 ◽

1992 ◽

Vol 131 (2) ◽

pp. 345-352 ◽

Cited By ~ 17

Author(s):

J C Eissenberg ◽

G D Morris ◽

G Reuter ◽

T Hartnett

Keyword(s):

Germ Line ◽

Position Effect ◽

Inducible Promoter ◽

Specific Protein ◽

P Element ◽

Position Effect Variegation ◽

Chromosomal Protein ◽

Gene Encoding ◽

Position Effects ◽

Effect Variegation

Abstract Chromosome rearrangements which place euchromatic genes adjacent to a heterochromatic breakpoint frequently result in gene repression (position-effect variegation). This repression is thought to reflect the spreading of a heterochromatic structure into neighboring euchromatin. Two allelic dominant suppressors of position-effect variegation were found to contain mutations within the gene encoding the heterochromatin-specific chromosomal protein HP-1. The site of mutation for each allele is given: one converts Lys169 into a nonsense (ochre) codon, while the other is a frameshift after Ser10. In flies heterozygous for one of the mutant alleles (Su(var)2-504), a truncated HP-1 protein was detectable by Western blot analysis. An HP-1 minigene, consisting of HP-1 cDNA under the control of an Hsp70 heat-inducible promoter, was transduced into flies by P element-mediated germ line transformation. Heat-shock driven expression of this minigene results in elevated HP-1 protein level and enhancement of position-effect variegation. Levels of variegating gene expression thus appear to depend upon the level of expression of a heterochromatin-specific protein. The implications of these observations for mechanism of heterochromatic position effects and heterochromatin function are discussed.

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