Worm Breeder's Gazette 2(2): 15
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Gonadogenesis in C. elegans provides an excellent system for the study of cellular differentiation. In C. elegans, male and hermaphrodite gonads develop from morphologically identical primordia. The small primordial gonad lies on the ventral side of the worm in the coelomic cavity and contains four nuclei at hatching. In the hermaphrodite, the primordium develops into a double-armed gonad encased by a cellular sheath displaying two-fold rotational symmetry. The hermaphrodite gonad produces first sperm and then oocytes. In the male, however, the primordium develops into an asymmetrical structure that lacks a cellular sheath and continuously produces sperm. A temperature-sensitive sex transformer mutant, tsB202 has been isolated (Devel. Biol. 52:1-18). tsB202 carries an autosomal recessive mutation in linkage group II that at restrictive temperature transforms an XX hermaphrodite into a phenotypic male, complete with a normal male gonad and vestigial external genitalia. Proper manipulation of the temperature regimen causes the production of intersexes. The transformed males and intersexes have been analyzed by electron microscopy and polyacrylamide gel electrophoresis. By EM analysis the gonads of the transformed males produced at 25.5 C are essentially identical to N2 male gonads, showing no cellular sheath in either the distal or proximal arms, normal spermatogenesis, limited core region in the distal arm, and a vas deferens. The gonads of the intersex forms predictably have characteristics of both male and hermaphrodite gonads depending upon the specific time of the temperature shift. The tsB202 male intersex produced by 9 hrs at 25.5 C followed by 80 hrs at 16 C has a male gonad with normal spermatogenesis and lacking a well-developed cellular sheath. Yet this male gonad shows oocyte differentiation similar to the N2 hermaphrodite. These oocytes are never fertilized and accumulate large quantities of DNA, yolk, and membranous material characteristic of unfertilized eggs of N2 hermaphrodites. The complementary hermaphrodite intersex, produced by 36 hrs at 16 C followed by 42 hrs at 25.5 C, has a hermaphrodite gonad with a cellular sheath similar to N2 hermaphrodites. Germ cells of the hermaphrodite intersex undergo normal spermatogenesis but fail to undergo oogenesis and oocytes are never produced. Sperm is overproduced (> 700 per arm) and a mature spermatheca does not form. One dimensional polyacrylamide gel electrophoretic patterns obtained from tsB202 transformed males are identical to those obtained from N2 males. Four major protein bands specific to eggs and oocytes are not present in tsB202 transformed males, tsB202 hermaphrodite intersexes, or N2 males. These four oocyte-specific bands are present in tsB202 male intersexes as well as N2 hermaphrodites. An EMS-induced revertant of tsB202 has been isolated and is currently being investigated.