Diversity,evolutionary contribution and ecological roles of aquatic viruses

Aquatic viruses include infected viruses in aquatic animals, plants and microorganisms, and free-floating viruses(virioplankton)in water environments. In the last three decades, a huge number of aquatic viruses, especially diverse free-floating viruses,including cyanophages, phycoviruses, archaea viruses, giant viruses, and even virophages, have been identified by virological experiments and metagenomic analyses. Based on a comprehensive introduction of aquatic virus classification and their morphological and genetic diversity, here, we summarize and outline main virus species, their evolutionary contribution to aquatic communities through horizontal gene transfer, and their ecological roles for cyanobacterial bloom termination and global biogeochemical cycling in freshwater and marine ecosystems. Thereby, some novel insights of aquatic viruses and virus-host interactions, especially their evolutionary contribution and ecological rolesin diverse aquatic communities and ecosystems, are highlighted in this review.

Leucine regulates lipid metabolism in adipose tissue through adipokine-mTOR-SIRT1 signaling pathway and bile acid—microbe axis in a finishing pig model

This study was conducted to explore the regulatory mechanism of leucine(Leu)on lipid metabolism of finishing pigs.Twenty-four Duroc×Landrace×Large cross pigs with an average body weight of68.33±0.97 kg were randomly allocated into 3 treatment groups with 8 replicates per group(1 pig per replicate).The dietary treatments were as follows:control group(CON),0.25%Leu group and 0.50%Leu group.The experimental period was 42 d.The results showed as follows.(1)Compared with the CON,0.25%and 0.50%Leu increased(P<0.01)the average daily gain(ADG),while the average backfat thickness(ABT)and the ratio of feed intake to body weight gain(F:G ratio)were decreased(P<0.05).(2)In the 0.25%Leu group,the relative mRNA expression levels of sterol regulatory element binding protein-1c(SREBP1c),recombinant fatty acid transport protein 1(FATP1),chemerin and peroxisome proliferatoractivated receptorγ(PPARγ)were decreased but the level of fatty acid binding protein 4(FABP4)and fatty acid translocase(FAT/CD36)were increased in backfat tissue.In the 0.25%Leu group,the protein levels of p-Rictor,p-Raptor,p-eIF4E-binding protein 1(p-4EBP1),p-silent mating type information regulator 2homolog 1(p-SIRT1)and acetylation ribosome s6 protein kinase 1(Ac—S6K1)were increased(P<0.05).(3)Compared to the CON,the diversity of gut microbiota in the 0.25%Leu group was increased.Principal component analysis showed that the relative abundance of Bacteroidetes,Lactobacillus and Desulfovibrio was higher in the 0.25%Leu group than the CON,but the relative abundance of Firmicutes,Treponema and Shigella was lower than in the CON(P<0.05).(4)Four different metabolites were screened out from the serum of finishing pigs including allolithocholic acid(alloLCA),isolithocholic acid(isoLCA),ursodeoxycholic acid(UDCA)and hyodeoxycholic acid(HDCA),which correlate to various degrees with the above microorganisms.In conclusion,Leu could promote adipose tissue lipolysis of finishing pigs through the mTOR-SIRT1 signaling pathway,and S6K1 is acetylated at the same time,and the interaction between gut microbiota and bile acid metabolism is also involved.

Diverse and variable sex determination mechanisms in vertebrates

Sex is prevalent in nature and sex determination is one of the most fundamental biological processes, while the way of initiating female and male development exhibits remarkable diversity and variability across vertebrates. The knowledge on why and how sex determination mechanisms evolve unusual plasticity remains limited. Here, we summarize sex determination systems,master sex-determining genes and gene-regulatory networks among vertebrates. Recent research advancements on sex determination system transition are also introduced and discussed in some non-model animals with multiple sex determination mechanisms. This review will provide insights into the origin, transition and evolutionary adaption of different sex determination strategies in vertebrates, as well as clues for future perspectives in this field.