As part of our effort to construct a physical map of the genome of the fission yeast Schizosaccharomyces pombe, we have made theoretical predictions for the progress expected, as measured by the expected length fraction of island coverage and by the expected properties ofthe anchored islands such as the number and the size of islands. Our experimental strategy is to construct a random clone library and screen the library for clones having unique sequence at both ends. This scheme is essentially the same as the clone-limited double sequence-tagged-site selection scheme which was used in a computer simulation by Palazzolo et al. IPalazzolo, M.

ABSTRACT. To better understand the reproductive transformation mechanism of Daphnia carinata, a Doublesex (Dsx) gene was cloned based on rapid amplification of cDNA ends (RACE), and was designated DapcaDsx2. Next, we compared similarities and assumed homology based on deduced amino acid sequences. It showed 97.52, 87.94, and 85.11% identity to orthologous genes in D. magna, D. pulex, and D. galeata respectively. Phylogenetic analysis revealed that DapcaDsx2 clustered in the same class, and was evolutionarily more distant to sequences from other species. qRT-PCR showed that DapcaDsx2 was most abundantly expressed during sexual reproduction (P < 0.05). Using digoxigenin-labeled RNA probes, we studied DapcaDsx2 expression in parthenogenetic and sexual females by whole-mount in situ hybridization. The results revealed that DapcaDsx2 was mainly Cloning and expression of Doublesex in D. carinata expressed in the second antennae and several sites of the ventral carapace, whereas higher expression levels were found in sexual than in parthenogenetic females. This suggests that the DapcaDsx2 gene is involved in switching modes of reproduction and in sexual differentiation.