Structure-Specific Abnormalities Associated with Mutations in a DNA Replication Accessory Factor in Drosophila

We have phenotypically and molecularly analyzed the cutlet locus in Drosophila. Homozygous cutlet flies exhibit abnormal development of a subset of adult tissues, including the eye, wing, and ovary. We show that abnormal development of these tissues is due to a defect in normal cell growth. Surprisingly, cell growth is affected in all developing precursor tissues in cutlet mutant animals, including those that give rise to phenotypically wild-type adult structures. The cutlet gene encodes a Drosophila homologue of yeast CHL12 and has similarity to mammalian replication factor C. In addition, cutlet genetically interacts with multiple subunits of Drosophila replication factor C. Our results suggest that the cutlet gene product acts as an accessory factor for DNA replication and has different requirements for the formation of various adult structures during Drosophila development.     

A hormonal and temporal analysis of the mechanisms involved in the control of ovulation induced by hemiovariectomy in the rat

The present study was undertaken to investigate the mechanisms of the stress-related ovulatory effects of hemicastration in the rat. Previous work (Roos et al., 1976) had shown that ovulation induced by unilateral ovariectomy (ULO) was suppressed in adrenalectomized females when ULO was performed on dioestrus III at 10--11 h in 5-day cyclic rats. Using the same experimental schema an increase in blood progesterone within 1 to 4 hours after ULO has been found to be present in adrenal intact females and suppressed in adrenalectomized rats. PB treatment (30 mg/kg, i.p.) concomitant with ULO at 10--11 h on dioestrus III significantly decreased the number of ovulating females without preventing blood progesterone concentration to increase at 12--13 h. A partial blockade of ovulation resulted from PB injection at 13 or 18 h. The ovulatory effects of ULO observed in females injected with PB at 23 h on dioestrus III or at 5 h on prooestrus were identical to those observed in hemiovariectomized non PB treated females. Only a small proportion of hemiovariectomized females displayed an LH release at 15--16 h and 17.30 h--18.30 h on dioestrus III. In contrast a significant FSH release was observed in this interval of time following ULO. Microscopic examination of the ovaries on prooestrus at either 11 h or 16 h revealed the presence of corpora lutea with morphological features corresponding to very different stages of development. We can conclude that progesterone of adrenal origin constituted the trigger of ovulation and caused LH-release during a time period extending from 13 h to 23 h on dioestrus III following ULO in the rat.