EVidenceModeler (EVM) is presented as an automated eukaryotic gene structure annotation tool that reports eukaryotic gene structures as a weighted consensus of all available evidence. EVM, when combined with the Program to Assemble Spliced Alignments (PASA), yields a comprehensive, configurable annotation system that predicts protein-coding genes and alternatively spliced isoforms. Our experiments on both rice and human genome sequences demonstrate that EVM produces automated gene structure annotation approaching the quality of manual curation.

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Automated Eukaryotic Gene Structure Annotation Using EVidenceModeler and the Program to Assemble Spliced Alignments

Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucleotide sequence of mitochondrial cytochrome b gene. Meantime relationships between the main cladogenetic events of the specialized schizothoracine fishes and the stepwise uplift of the Qinghai-Tibetan Plateau are also conducted using the molecular clock, which is calibrated by geological isolated events between the upper reaches of the Yellow River and the Qinghai Lake. Results indicated that the specialized schizothoracine fishes are not a monophyly. Five species and subspecies of Ptychobarbus form a monophyly. But three species of Gymnodiptychus do not form a monophyly. Gd.integrigymnatus is a sister taxon of the highly specialized schizothoracine fishes while Gdo pachycheilus has a close relation with Gd. dybowskii, and both of them are as a sister group of Diptychus maculatus. The specialized schizothoracines fishes might have originated during the Miocene(about 10 MaBP), and then the divergence of three genera happened during late Miocene (about 8 MaBP). Their main specialization occurred during the late Pliocene and Pleistocene (3.54-0.42 MaBP). The main cladogenetic events of the specialized schizothoracine fishes are mostly correlated with the geological tectonic events and intensive climate shift happened at 8, 3.6, 2.5 and 1.7 MaBP of the late Cenozoic.Molecular clock data do not support the hypothesis that the Qinghai-Tibetan Plateau uplifted to near present or even higher elevations during the Oligocene or Miocene, and neither in agreement with the view that the plateau uplifting reached only to an altitude of 2000 m during the late Pliocene(about 2.6 MaBP).

Molecular phylogeny of the specialized schizothoracine fishes （Teleostei： Cyprinidae）,with their implications for the uplift of the Qinghai-Tibetan Plateau

Fish biology has been developed for more than 100 years, but some important breakthroughs have been made in the last decade. Early studies commonly concentrated on morphology, phylogenetics, development, growth, reproduction manipulation, and disease control. Recent studies have mostly focused on genetics, molecular biology, genomics, and genome biotechnologies, which have provided a solid foundation for enhancing aquaculture to ensure food security and improving aquatic environments to sustain ecosystem health. Here, we review research advances in five major areas: (1) biological innovations and genomic evolution of four significant fish lineages including non-teleost ray-finned fishes, northern hemisphere sticklebacks, East African cichlid fishes, and East Asian cyprinid fishes; (2) evolutionary fates and consequences of natural polyploid fishes; (3) biological consequences of fish domestication and selection; (4) development and innovation of fish breeding biotechnologies; and (5) applicable approaches and potential of fish genetic breeding biotechnologies. Moreover, five precision breeding biotechniques are examined and discussed in detail including gene editing for the introgression or removal of beneficial or detrimental alleles, use of sex-specific markers for the production of mono-sex populations, controllable primordial germ cell on-off strategy for producing sterile offspring, surrogate broodstock-based strategies to accelerate breeding, and genome incorporation and sexual reproduction regain-based approach to create synthetic polyploids. Based on these scientific and technological advances, we propose a blueprint for genetic improvement and new breed creation for aquaculture species and analyze the potential of these new breeding strategies for improving aquaculture seed industry and strengthening food security.

Rethinking fish biology and biotechnologies in the challenge era for burgeoning genome resources and strengthening food security

Fish biology has been developed for more than 100 years, but some important breakthroughs have been made in the last decade. Early studies commonly concentrated on morphology, phylogenetics, development, growth, reproduction manipulation, and disease control. Recent studies have mostly focused on genetics, molecular biology, genomics, and genome biotechnologies, which have provided a solid foundation for enhancing aquaculture to ensure food security and improving aquatic environments to sustain ecosystem health. Here, we review research advances in five major areas: (1) biological innovations and genomic evolution of four significant fish lineages including non-teleost ray-finned fishes, northern hemisphere sticklebacks, East African cichlid fishes, and East Asian cyprinid fishes; (2) evolutionary fates and consequences of natural polyploid fishes; (3) biological consequences of fish domestication and selection; (4) development and innovation of fish breeding biotechnologies; and (5) applicable approaches and potential of fish genetic breeding biotechnologies. Moreover, five precision breeding biotechniques are examined and discussed in detail including gene editing for the introgression or removal of beneficial or detrimental alleles, use of sex-specific markers for the production of mono-sex populations, controllable primordial germ cell on-off strategy for producing sterile offspring, surrogate broodstock-based strategies to accelerate breeding, and genome incorporation and sexual reproduction regain-based approach to create synthetic polyploids. Based on these scientific and technological advances, we propose a blueprint for genetic improvement and new breed creation for aquaculture species and analyze the potential of these new breeding strategies for improving aquaculture seed industry and strengthening food security. 

Black rockfish (Sebastes schlegelii) is an economically important viviparous marine teleost in Japan, Korea, and China. It is characterized by internal fertilization, long-term sperm storage in the female ovary, and a high abortion rate. For better understanding the mechanism of fertilization and gestation, it is essential to establish a reference genome for viviparous teleosts. Herein, we used a combination of Pacific Biosciences sequel, Illumina sequencing platforms, 10× Genomics, and Hi-C technology to obtain a genome assembly size of 848.31 Mb comprising 24 chromosomes, and contig and scaffold N50 lengths of 2.96 and 35.63 Mb, respectively. We predicted 39.98% repetitive elements, and 26,979 protein-coding genes. S. schlegelii diverged from Gasterosteus aculeatus ∼32.1-56.8 million years ago. Furthermore, sperm remained viable within the ovary for up to 6 months. The glucose transporter SLC2 showed significantly positive genomic selection, and carbohydrate metabolism-related KEGG pathways were significantly up-regulated in ovaries after copulation. In vitro suppression of glycolysis with sodium iodoacetate reduced sperm longevity significantly. The results indicated the importance of carbohydrates in maintaining sperm survivability. Decoding the S. schlegelii genome not only provides new insights into sperm storage; additionally, it is highly valuable for marine researchers and reproduction biologists.

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Sequencing of the black rockfish chromosomal genome provides insight into sperm storage in the female ovary

Animal genomes in the Qinghai-Tibetan Plateau provide valuable resources for scientists to understand the molecular mechanism of environmental adaptation. Tibetan fish species play essential roles in the local ecology; however, the genomic information for native fishes was still insufficient. Oxygymnocypris stewartii, belonging to Oxygymnocypris genus, Schizothoracinae subfamily, is a native fish in the Tibetan plateau living within the elevation from roughly 3,000 m to 4,200 m. In this report, PacBio and Illumina sequencing platform were used to generate ~385.3 Gb genomic sequencing data. A genome of about 1,849.2 Mb was obtained with a contig N50 length of 257.1 kb. More than 44.5% of the genome were identified as repetitive elements, and 46,400 protein-coding genes were annotated in the genome. The assembled genome can be used as a reference for future population genetic studies of O. stewartii and will improve our understanding of high altitude adaptation of fishes in the Qinghai-Tibetan Plateau.

The sequence and de novo assembly of Oxygymnocypris stewartii genome.

Genome of Tetraploid Fish Schizothorax o'connori Provides Insights into Early Re-diploidization and High-Altitude Adaptation.

There are wide genomic and phenotypic differences between Asian and European pig breeds, yet the current reference genome is the European Duroc pig genome. A high-quality pig genome is lacking for genetic analysis of agricultural traits in Asian pigs. Here, using a hybrid approach, a high-quality reference genome (MSCAAS v1) for the Asian Meishan breed is assembled with a contig N50 size of 48.05 Mb. MSCAAS v1 outperforms the Duroc genome as a reference genome for Asian breeds. Genomic comparison reveals 49,103 structural variations (SVs) between Meishan and Duroc, 4.02% of which are Asian-specific SVs (AP-SVs). Notably, a 30-Mb hotspot for AP-SVs on chromosome X enriched for genes associated with Asian-pig-specific phenotypes is present in Asian domestic pig breeds, but absent in Asian wild boars, suggesting that Asian domestic breeds share a common ancestor. Interbreed transcriptomics reveals transcriptional suppression roles of AP-SVs in multiple tissues. Finally, transcriptional regulation in the intron of IGF2R is reported, as genomic SV (274-bp deletion) in Tibetan pig limits its growth compared to domestic pig breeds. In summary, this study provides insights regarding the genetic changes underlying pig domestication and presents a benchmark-setting resource for the utilization of agricultural valuable loci in Asian pigs.

Di Wang

Papers

The sequence and de novo assembly of Oxygymnocypris stewartii genome.

Genome of Tetraploid Fish Schizothorax o'connori Provides Insights into Early Re-diploidization and High-Altitude Adaptation.

The Meishan pig genome reveals structural variation-mediated gene expression and phenotypic divergence underlying Asian pig domestication