Congress Abstracts - Society for Developmental Biology

Penaeid shrimp represent an important global food resource, yet little is known of their basic developmental biology. To find genes
involved in early development, M. japonicus embryos were manually separated at the 2-cell stage and allowed to develop to the time
when controls had reached the limb bud stage. Animal and vegetal half-embryos were pooled; total RNA was isolated, converted to
cDNA, and amplified for Ion Torrent sequencing. This resulted in 472,512 reads from vegetal half-embryos and 487,511 reads from
animal half-embryos which were assembled as contigs and computationally subtracted from each other, producing 41,567 vegetal and
46,781 animal contigs. The transcriptome libraries were BLAST’d for selected developmental toolkit genes. Genes found included the
sex determination genes sex lethal and transformer-2 (both transcriptomes); potential germ line genes ddx3x (vegetal transcriptome
only), ddx17, mex-3 (animal transcriptome), argonaute 1, ddx5, pumilio, SmB , and staufen (both); mesoderm transcription factors
brachyury, twist (vegetal), mef2 , and snail1 (both); the axial or segmentation genes deformed, engrailed, hunchback, wingless/wnt-8
(vegetal), kruppel, orthodencticle (animal), β-catenin, distal-less , giant , and hairy (both). Other genes found included par-6,
trithorax, myosin, troponin C1 and I (vegetal), cyclins A, B, I, polycomb (animal), gsk3, notch2, par-1 , and retinoblastoma-1 (both).
Contigs in each transcriptome were also ranked by number of repeats, indicating increasing probability that the contig was unique to
one transcriptome and not the other. The sex determination, germ line, and mesoderm genes were examined more closely for
developmental expression by qPCR. The results will be reported.
Program/Abstract # 179
Comprehensive screening of sexualization-induced genes in planarian
Matsumoto, Midori; Ueda, Kento; Takagi, Souta (Keio Univesity, Japan); Yoshitake, Kazutoshi; Gojyobori, Takashi (National
Institute of Genetics, Japan)
The reproductive mode is classified into asexual reproduction and sexual reproduction, which have merit and demerit respectively.
And there are some species, which change reproductive mode in order to produce offspring suitable for the environment. The
planarian Dugesia ryukyuensis reproduces both asexually and sexually, and can switch from one mode of reproduction to the other.
We have established the experimental method, which can change asexual reproduction to sexual reproduction in D. ryukyuensis, by
feeding with the putative sexualizing substance contained in Bdellocephala brunnea. The sexualization process is divided into five
distinct stages by histological changes and it has a point-of-no-return after which the worms could spontaneously develop sexual
organs without feeding further with B. brunnea. In this study, we tried to identify the sexualization-induced genes by RNAseq, Real
Time-PCR and RNA interference (RNAi). By this comprehensive screening, we selected five candidate genes for sexualizationinduced
genes. They increased or decreased the expression levels in the early stage of the sexualization. One candidate gene (C.3604)
of them was annotated to Schimidtea mediterranea prohormone convertase 2 (PC2). By RNAi during sexualization, the knockdown of
C.3604 did not develop sexual organs like ovary, testis, genital pore and copulatory apparatus. Therefore, it has been suggested that
C.3604 has crucial role for producing the sexualizing substances and inducing sexualization.
Program/Abstract # 180
Meiotic chromosome behavior in the triploid planarian: Function of rad51 homolog in gametogenesis
Chinone, Ayako; Matsumoto, Midori (Keio Univesity, Japan)
It is generally assumed that triploid organisms reproduce only asexually, because they tend to produce aneuploid gametes due to
problems of chromosomal pairing and segregation during meiosis. However, triploid individuals of Dugesia ryukyuensis can
reproduce bisexually. They develop hermaphrodite sexual organs by artificial feeding of sexually matured planarians, produce
functional gametes and begin reproducing by copulation. The previous report showed that meiosis occurs in both male and female
germline. In this study, we observed the meiotic chromosomes in both germlines in the triploid planarian. The male germ-line cells
are likely to eliminate haploid set of chromosomes before onset of meiosis, and then haploid sperms are exclusively produced. On the
other hand, the female germ-line cells appear to stay triploid until meiotic prophase I, and then both haploid and diploid eggs are
produced. To investigate the detailed processes and mechanisms of meiosis in both germline, we focused on rad51 gene, which is
known to assist in repair of DNA double strand breaks and be involved in pairing of homologous chromosomes during meiotic
prophase I. We cloned a rad51 ortholog (Dr-rad51) in D. ryukyuensis and found that Dr-rad51 was expressed in oocytes and
spermatocytes of triploid sexualized planarian. During the sexualizing process, Dr-rad51 (RNAi) worms failed to develop ovaries and
delayed to develop testes but somatic sexual organs were unaffected. In addition, it appears that pairing of chromosomes was failed in
oocytes of Dr-rad51 (RNAi) while sperms are produced normally. These results suggest that recombination regulated by Rad51 is
necessary for at least oogenesis.
Program/Abstract # 181
Claudins are essential regulators of morphogenesis
Ryan, Aimee K. (McGill University / RI-MUHC, Canada), Baumholtz, Amanda; Collins, Michelle; Simard, Annie; Khairallah, Halim
(McGill University, Montreal, Canada); El Andalousi, Jasmine; Gupta, Indra (RI-MUHC, Montreal, Canada)
Morphogenesis is a highly orchestrated series of events that transforms groups of cells into complex 3-dimensional tissues or organs.
There are still large gaps in our understanding of how changes in behaviours of individual cells are coordinated with cellular
rearrangements occurring at the level of the tissue. Tight junctions are appropriately positioned to coordinate these behaviours. We
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