SPERMIOGENESIS IN WILD TYPE AND IN A MALE STERILITY MUTANT OF DROSOPHILA MELANOGASTER

Abstract

Spermiogenesis in the translocation heterozygote T (1; 2H) 25(20) y l 25/FM6 has been studied with the electron microscope and compared with that in wild type males. It appears that the genetic lesion in the male sterility mutant is associated primarily with a failure in differentiation of the head. In wild type flies, the spermatid nucleus assumes a conchoidal shape; chromatin accumulates along the convex surface. Adjacent to the concave surface a large bundle of microtubules runs parallel to the long axis of the spermatid. A single row of microtubules is juxtaposed against the convex surface of the head. As differentiation proceeds, the nucleus elongates, chromatin condenses, and the nucleus is compacted to a final diameter of about 0.3 #. In the sterile mutant the spermatid nucleus has an irregular or wedge-shaped profile and no concavity is formed, nor is the bundle of microtubules observed. The row of microtubules, however, is usually present around the periphery. The change from lysine-rich to arginine-rich histone in mature wild type sperm does not occur in the sterile male. The substructure of the axial filament and mitochondrial derivatives, however, are similar to those in wild type.

Epigenetic effects of polymorphic Y chromosomes modulate chromatin components, immune response, and sexual conflict

“…Furthermore, in view of potentially strong sibling-sibling competition in the progeny of Drosophila, population genetic theory predicts that harmful interactions between the mitochondria and the Y chromosome might evolve (1). In Drosophila, harmful interactions might be further enhanced through the dramatic mitochondrial remodeling that occurs during spermatogenesis and that leads to the mitochondrial derivatives found in the fruit fly sperm (26). YRV targets are enriched for genes with functional roles related to the mitochondria (13), presumably as a byproduct of genetic interactions between the Y chromosome and mitochondria that occur during spermatogenesis.…”

The Drosophila Copper Transporter Ctr1C Functions in Male Fertility

“…At present, we can only speculate about the nature of such a role. Sperm motility depends on the function of the mitochondrial respiratory chain (39); Drosophila sperm contain a large so-called mitochondrial derivative in the head region (40) and might have a high copper demand for proper mitochondrial function. Intriguingly, high levels of Ctr1 are present in mature spermatozoa in the mouse (41), and Ctr2 levels are high in testis.…”

Rôles indirects des microtubules dans la morphogenèse nucléaire des spermatides

“…Leur absence (Kettaneh et Hartl, 1976 ;Baccetti et al, 1977) ou leur alkylation expérimentale (Courtens et a/., 1980) (Mclntosh et Porter, 1967). Malheureusement, chez le Pinson (Fawcett et al, 1971) ou chez quelques vers annélides (Malecha, 1975) (Shoup, 1967) Bennett, 1974 ;Hillman et Nadijcka, 1978).…”

“…Ces faits, associés à la découverte récente de liens unissant la chromatine intranucléaire à la manchette, au travers de l'enveloppe nucléaire, chez au moins trois mammifères b), laissent à penser que la manchette pourrait jouer un rôle « inducteur » (Shoup, 1967 ;Tokuyasu, 1974 ;Malecha, 1975) (Courtens et Mattei, 1976), les nématodes (Jamuar, 1966), les chaetognathes (Van Deurs, 1975), de nombreux poissons téléostéens (Stanley, 1969), et les scorpionidés (Jespersen et Hartwick, 1973 ;Phillips, 1974) (Zirkin, 1975 (Mattei et Mattei, 1973) McGregor, 1968), chez les prochordés (Tuzet et al, 1972), chez quelques rares poissons , et chez les oiseaux colombiformes (Mattei et al, 1972). Selon les étapes de la spermiogenèse, les fibres de chromatine s'orientent par rapport à l'un ou l'autre des systèmes, le second prenant parfois le relai du premier (Tuzet et al, 1972 …”