Genome architecture changes and major gene variations of Andrias davidianus ranavirus (ADRV)

Ranaviruses are emerging pathogens that have led to global impact and public concern. As a rarely endangered species and the largest amphibian in the world, the Chinese giant salamander, Andrias davidianus, has recently undergone outbreaks of epidemic diseases with high mortality. In this study, we isolated and identified a novel ranavirus from the Chinese giant salamanders that exhibited systemic hemorrhage and swelling syndrome with high death rate in China during May 2011 to August 2012. The isolate, designated Andrias davidianus ranavirus (ADRV), not only could induce cytopathic effects in different fish cell lines and yield high viral titers, but also caused severely hemorrhagic lesions and resulted in 100% mortality in experimental infections of salamanders. The complete genome of ADRV was sequenced and compared with other sequenced amphibian ranaviruses. Gene content and phylogenetic analyses revealed that ADRV should belong to an amphibian subgroup in genus Ranavirus, and is more closely related to frog ranaviruses than to other salamander ranaviruses. Homologous gene comparisons show that ADRV contains 99%, 97%, 94%, 93% and 85% homologues in RGV, FV3, CMTV, TFV and ATV genomes respectively. In addition, several variable major genes, such as duplicate US22 family-like genes, viral eukaryotic translation initiation factor 2 alpha gene and novel 75L gene with both motifs of nuclear localization signal (NLS) and nuclear export signal (NES), were predicted to contribute to pathogen virulence and host susceptibility. These findings confirm the etiologic role of ADRV in epidemic diseases of Chinese giant salamanders, and broaden our understanding of evolutionary emergence of ranaviruses

Research on the Employment Promotion Countermeasures of post-00s college students

The post-00s (the Generation after 00s) college students in the new era show the characteristics of slow employment. In order to promote the employment of contemporary college students, this paper analyzes the psychological and ideological problems of slow employment of post-00s college students through questionnaire survey on the dynamic employment thought, value orientation, employment location, professional satisfaction and other issues of contemporary college students. A series of employment promotion strategies adapted to the characteristics of college students under the new situation are put forward from the aspects of perfecting the curriculum system of employment guidance, improving the guidance ability of employment guidance teachers, perfecting the employment guidance and service system of graduates

jiankangliuapioneerofsexdeterminationstudiesinvertebrates

Sixty-eight years ago, Dr. W.S. Bullough, a Fellow of the Royal Society, published an article ＂Hermaphroditism in the lower vertebrates＂ in Nature （Bullough, 1947） and thereby commented a significant finding in lower vertebrate sex mechanism fulfilled by a young Chinese scholar Jian-Kang Liu （刘健康, C.K. Liu） （Fig. 1 ）. At the beginning of the article, Dr. Bullough respectfully acknowledged that： ＂By the publi- cation in 1944 of a description of the gonads of Monopterus javanensis Lac. （Symbranchii; Teleostei） （Liu, 1944a）, Liu has furnished new and interesting evidence concerning the mechanism of sex determination in the lower vertebrates, and has opened a fresh field for research into this subject＂ （Bullough, 1947）

Natural and artificial polyploids in aquaculture

Genome polyploidy has been revealed to result in evolutionary advantages and novelties, and therefore, polyploid aquatic animals may possess excellent traits of economic interest including rapid growth, extensive adaptability and disease resistance. For this reason, numerous species of natural polyploid fishes, such as common carp, gibel carp, crucian carp, salmon, and sturgeon, were chosen as important target species for aquaculture. Many artificial polyploids have been commercially utilized for aquaculture and most of them were created from natural polyploid fishes of the Cyprinidae and Salmonidae. Thanks to the easy mass production and better economic traits in growth and flesh quality, the synthetized autopolyploids or allopolyploids from natural polyploid species in cyprinid fishes have been extensively applied to aquaculture throughout China. This review outlines polyploidy advantages and innovative opportunities, lists natural polyploid species used in aquaculture, and summarizes artificial polyploids that have been induced or synthetized, and used in aquaculture. Moreover, some main research trends on polyploid utilization and ploidy manipulation of aquaculture animals are also introduced and discussed in the review

Research on the Employment Promotion Countermeasures of post-00s college students

The post-00s (the Generation after 00s) college students in the new era show the characteristics of slow employment. In order to promote the employment of contemporary college students, this paper analyzes the psychological and ideological problems of slow employment of post-00s college students through questionnaire survey on the dynamic employment thought, value orientation, employment location, professional satisfaction and other issues of contemporary college students. A series of employment promotion strategies adapted to the characteristics of college students under the new situation are put forward from the aspects of perfecting the curriculum system of employment guidance, improving the guidance ability of employment guidance teachers, perfecting the employment guidance and service system of graduates

De novo transcriptome assembly of four organs of Collichthys lucidus and identification of genes involved in sex determination and reproduction

The spinyhead croaker (Collichthys lucidus) is a commercially important fish species, which is mainly distributed in the coastal regions of China. However, little is known about the molecular regulatory mechanism underlying reproduction in C. lucidus. A de novo transcriptome assembly in brain, liver, ovary and testis tissues of C. lucidus was performed. Illumina sequencing generated 60,322,004, 57,044,284, 60,867,978 and 57,087,688 clean reads from brain, liver, ovary and testis tissues of C. lucidus, respectively. Totally, 131,168 unigenes with an average length of 644 bp and an N50 value of 1033 bp were assembled. In addition, 1288 genes were differentially expressed between ovary and testis, including 442 up-regulated and 846 down-regulated in ovary. Functional analysis revealed that the differentially expressed genes between ovary and testis were mainly involved in the function of sexual reproduction, sex differentiation, development of primary male sexual characteristics, female gamete generation, and male sex differentiation. A number of genes which might be involved in the regulation of reproduction and sex determination were found, including HYAL and SYCP3 and BMP15. Furthermore, 35,476 simple sequence repeats (SSRs) were identified in this transcriptome dataset, which would contribute to further genetic and mechanism researches. De novo transcriptome sequencing analysis of four organs of C. lucidus provides rich resources for understanding the mechanism of reproductive development of C. lucidus and further investigation of the molecular regulation of sex determination and reproduction of C. lucidus

Two Novel lncRNAs Regulate Primordial Germ Cell Development in Zebrafish

Long noncoding RNAs (lncRNAs) are regulatory transcripts in various biological processes. However, the role of lncRNAs in germline development remains poorly understood, especially for fish primordial germ cell (PGC) development. In this study, the lncRNA profile of zebrafish PGC was revealed by single cell RNA-sequencing and bioinformatic prediction. We established the regulation network of lncRNA-mRNA associated with PGC development, from which we identified three novel lncRNAs—lnc172, lnc196, and lnc304—highly expressing in PGCs and gonads. Fluorescent in situ hybridization indicated germline-specific localization of lnc196 and lnc304 in the cytoplasm and nucleus of spermatogonia, spermatocyte, and occyte, and they were co-localized with vasa in the cytoplasm of the spermatogonia. By contrast, lnc172 was localized in the cytoplasm of male germline, myoid cells and ovarian somatic cells. Loss- and gain-of-function experiments demonstrated that knockdown and PGC-specific overexpression of lnc304 as well as universal overexpression of lnc172 significantly disrupted PGC development. In summary, the present study revealed the lncRNA profile of zebrafish PGC and identified two novel lncRNAs associated with PGC development, providing new insights for understanding the regulatory mechanism of PGC development