Dayan A. Perera

Male-biased genes in catfish as revealed by RNA-Seq analysis of the testis transcriptome.

Background Catfish has a male-heterogametic (XY) sex determination system, but genes involved in gonadogenesis, spermatogenesis, testicular determination, and sex determination are poorly understood. As a first step of understanding the transcriptome of the testis, here, we conducted RNA-Seq analysis using high throughput Illumina sequencing. Methodology/Principal Findings A total of 269.6 million high quality reads were assembled into 193,462 contigs with a N50 length of 806 bp. Of these contigs, 67,923 contigs had hits to a set of 25,307 unigenes, including 167 unique genes that had not been previously identified in catfish. A meta-analysis of expressed genes in the testis and in the gynogen (double haploid female) allowed the identification of 5,450 genes that are preferentially expressed in the testis, providing a pool of putative male-biased genes. Gene ontology and annotation analysis suggested that many of these male-biased genes were involved in gonadogenesis, spermatogenesis, testicular determination, gametogenesis, gonad differentiation, and possibly sex determination. Conclusion/Significance We provide the first transcriptome-level analysis of the catfish testis. Our analysis would lay the basis for sequential follow-up studies of genes involved in sex determination and differentiation in catfish.

Identification of a sex-linked marker for channel catfish

Source/description: Fifty-three additional markers (EST and BAC end sequence) linked to the sex-determining region (U6, LG14) in a previous catfish linkage map were genotyped using sexually mature progeny generated by an F1 channel catfish (Ictalurus punctatus) · blue catfish (I. furcatus) hybrid backcrossed for two generations to channel catfish (F2-3 # · Kansas Ch-606

Effect of Sodium Chloride on Hatching Rate on Channel Catfish, Ictalurus punctatus, Embryos

). Thirty-two males and 32 females from this family were sexed based on external genitalia. Blood samples were then collected for genotyping.

Salt Sensitive Tet-Off-Like Systems to Knockdown Primordial Germ Cell Genes for Repressible Transgenic Sterilization in Channel Catfish, Ictalurus punctatus

Channel catfish, Ictalurus punctatus, eggs were hatched statically in 0, 2, 4, or 6 ppt salinity. Hatching rate was highest (P < 0.05) in 4 ppt treatments, 60%–82%. Hatching rate was 17%–52%, 46%–75%, and 32%–47% for 0, 2, and 6 ppt treatments, respectively. The high salt levels had adverse post-hatch effects as fry in the 4 and 6 ppt treatments had heavy post-hatch mortality and difficulty absorbing their yolk sac. The 0 ppt treatment experienced fungal infection, but no fungal growth was observed for the other treatments. Embryo mortality was observed between 24–48 hpf in the 6 ppt treatment, a time frame that may coincide with a developmental stage of the embryo that is sensitive to high salt concentrations as well as to other chemical treatments used to treat egg diseases. Developmental rate slowed with increasing salinity. The 2 ppt treatment appears to be the best treatment considering the post-hatch mortality in the 4 ppt treatment. Salinity levels between 2 and 4 ppt should be evaluated as well as variable treatment levels considering that 4 ppt had the most consistently high hatching rate, but heavy post-hatch mortality, which may require a reduction in salt level just prior to hatch to take advantage of the elevated hatch at 4 ppt. Partial budgeting indicated that the salt treatment for the eggs was economically beneficial, increasing net profit by

Relative effectiveness of carp pituitary extract, luteininzing hormone releasing hormone analog (LHRHa) injections and LHRHa implants for producing hybrid catfish fry

272,502 for a hatchery that is producing 10 million fry in 117 hatching troughs (379 L) without salt.

Effect of strain on the growth, survival and sexual dimorphism of channel × blue catfish hybrids grown in earthen ponds ☆

Repressible knockdown approaches were investigated for transgenic sterilization in channel catfish, Ictalurus punctatus. Two primordial germ cell (PGC) marker genes, nanos and dead end, were targeted for knockdown, and an off-target gene, vasa, was monitored. Two potentially salt sensitive repressible promoters, zebrafish adenylosuccinate synthase 2 (ADSS) and zebrafish racemase (Rm), were each coupled with four knockdown strategies: ds-sh RNA targeting the 5′ end (N1) or 3′ end (N2) of channel catfish nanos, full-length cDNA sequence of channel catfish nanos for overexpression (cDNA) and ds-sh RNA targeting channel catfish dead end (DND). Each construct had an untreated group and treated group with sodium chloride as the repressor compound. Spawning rates of full-sibling P1 fish exposed or not exposed to the constructs as treated and untreated embryos were 93% and 59%, respectively, indicating potential sterilization of fish and repression of the constructs. Although the mRNA expression data of PGC marker genes were inconsistent in P1 fish, most F1 individuals were able to downregulate the target genes in untreated groups and repress the knockdown process in treated groups. The results indicate that repressible transgenic sterilization is feasible for reproductive control of fish, but more data from F2 or F3 are needed for evaluation.