title: Male-biased genes in catfish as revealed by RNA-Seq analysis of the testis transcriptome.
abstract: 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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, Alabama, USA.
authors.forename: Fanyue
authors.initials: F
authors.lastname: Sun
authors.forename: Shikai
authors.initials: S
authors.lastname: Liu
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Gao
authors.forename: Yanliang
authors.initials: Y
authors.lastname: Jiang
authors.forename: Dayan
authors.initials: D
authors.lastname: Perera
authors.forename: Xiuli
authors.initials: X
authors.lastname: Wang
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.forename: Luyang
authors.initials: L
authors.lastname: Sun
authors.forename: Jiaren
authors.initials: J
authors.lastname: Zhang
authors.forename: Ludmilla
authors.initials: L
authors.lastname: Kaltenboeck
authors.forename: Rex
authors.initials: R
authors.lastname: Dunham
authors.forename: Zhanjiang
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D002397:Catfishes / Q000235:genetics*; D005260:Female; D063990:Gene Ontology; D008040:Genetic Linkage; D059014:High-Throughput Nucleotide Sequencing; D008297:Male; D058977:Molecular Sequence Annotation; D012727:Sex Characteristics; D019849:Sex Determination Processes; D013091:Spermatogenesis / Q000235:genetics; D013737:Testis / Q000378:metabolism*; D059467:Transcriptome / Q000235:genetics*