Long-read genome assemblies reveal a cis-regulatory landscape associated with phenotypic divergence in two sister Siniperca fish species

Due to the difficulty in accurately identifying structural variants(SVs) across genomes,their impact on cisregulato ry diverge n ce of closely related species,especially fish,remains to be explored.Recently identified broad H3K4me3 domains are essential for the regulation of genes involved in several biological processes.However,the role of broad H3K4me3 domains in phenotypic divergence remains poorly understood.Siniperca chuatsi and S.scherzeri are closely related but divergent in several phenotypic traits,making them an ideal model to study cis-regulatory evolution in sister species.Here,we generated chromosome-level genomes of S.chuatsi and S.scherzeri,with assembled genome sizes of 716.35 and740.54 Mb,respectively.The evolutionary histories of S.chuatsi and S.scherzeri were studied by inferring dynamic changes in ancestral population sizes.To explore the genetic basis of adaptation in S.chuatsi and S.scherzeri,we performed gene family expansion and contraction analysis and identified positively selected genes(PSGs).To investigate the role of SVs in cis-regulatory divergence of closely related fish species,we identified high-quality SVs as well as divergent H3K27ac and H3K4me3 domains in the genomes of S.chuatsi and S.scherzeri.Integrated analysis revealed that cis-regulatory divergence caused by SVs played an essential role in phenotypic divergence between S.chuatsi and S.scherzeri.Additionally,divergent broad H3K4me3 domains were mostly associated with cancer-related genes in S.chuatsi and S.scherzeri and contributed to their phenotypic divergence.

Microstructure,crystallography and nucleation mechanism of NANOBAIN steel

The microstructure of bainite ferrite in NANOBAIN steel transformed at different temperatures was investigated by scanning electron microscopy, transmission electron microscopy, electron back-scattered diffraction, and vickers hardness tester in detail. It is found that the average width of bainitic ferrite （BF） plates can be refined to be thinner with the reduction of temperature （473-573 K）, and the bainitic ferrite plates can reach up to 20-74 nm at 473 K. Crystallographic analysis reveals that the bainitic ferrite laths are close to the Nishiyama-Wasserman orientation relationship with their parent austenite. Temperature shows a significant effect on the variant selection, and a decrease in temperature generally weakens the variant selection. Thermodynamic analyses indicates that the Lacher, Fowler and Guggenheim （LFG） model is more suitable than the Kaufman, Radcliffe and Cohen （KRC） model dealing with NANOBAIN steel at a low temperature range. The free energy change △G^γ→BF is about -1500 J.mol^-1 at 473 K, which indicates that nucleation in NANOBAIN steel is the shear mechanism. Finally, the formation of carbon poor regions is thermodynamically possible, and the existence of carbon poor regions can greatly increase the possibility of the shear mechanism.

Effects of ausforming strain on bainite transformation in nanostructured bainite steel

The effects of ausforming strain on bainite transformation in high-carbon low-alloy nanobainite steel were investigated using a Gleeble 3500 thermomechanical simulator machine.The bainite transformation speed at 300°C was found to be accelerated by ausforming at 300,600,and 700°C under applied strains ranging from 10% to 50% followed by isothermal transformation at 300°C.The ausformed bainite volume fraction varied with the ausforming strain because of the mechanical stabilization of the deformed austenite.Ausforming at low temperatures not only enhanced the bainite ferrite volume fraction but also refined the microstructure substantially.Although the amount of bainite ferrite might have been reduced with increasing strain,the microstructures were refined by ausforming.

Effect of Nb on Microstructure and Mechanical Properties in Non-magnetic High Manganese Steel

Microstructure and mechanical properties of two kinds of non-magnetic high manganese steels with and without Nb addition which experienced the same rolling and heating treatment were investigated by means of scan ning electron microscopy, electron back-scattered diffraction, transmission electron microscopy, X-ray diffraction and tensile test. It was found that the microstructure of the high manganese steel was refined by the Nb addition. Moreover, steel with Nb addition has a higher stacking fault energy which favors the deformation twinning, Twin ning is the most important deformation mechanism in the Nb-bearing steel. Therefore, steel with Nb addition has much higher strength and higher plasticity. The product of tensile strength and total elongation exceeds 61.8 GPa ·%. In addition, steel with Nb addition also has excellent non magnetic property.

The shrimp IKK-NF-KB signaling pathway regulates antimicrobial peptide expression and may be subverted by white spot syndrome virus to facilitate viral gene expression

The IκB kinases IKKα and IKKβ and the IKK-related kinases TANK-binding kinase 1 （TBK1） and IKKε are the master regulators of the NF-κB signaling pathway. Although this pathway has been extensively studied in mammals, less attention has been paid in crustaceans, which have significant economic value. Here, we report the cloning and functional studies of two IKK homologs, LvlKKβ and LvlKKε, from Pacific white shrimp, Litopenaeus vannamei. LvlKKβ and LvlKKα mRNAs are widely expressed in different tissues and are responsive to white spot syndrome virus （WSSV） infection. When overexpressed in Drosophila S2 cells, LvlKKβ but not LvlKKε activates the promoters of NF-κB pathway-controlled antimicrobial peptide genes （AMPs）, such as the Penaeidins （PENs）. In HEK 293T cells, both LvlKKβ and LvlKKε activate an NF-κB reporter. The silencing of LvlKKβ or LvlKKε using double-stranded RNA （dsRNA）-mediated RNA interference （RNAi） decreases the expression of L. vannamei AMPs, including PENs, lysozyme and crustins. Intriguingly, LvlKKβ- or LvlKKε-silenced L. vannameiare resistant to WSSV infection. We hypothesized that successful infection with WSSV requires the activation of the IKK-NF-κB signaling pathway to modulate viral gene expression. We constructed luciferase reporters for 147 WSSV genes. By screening, we found that the WSSV051, WSSV059, WSSV069, WSSV083, WSSV090, WSSV107, WSSV244, WSSV303, WSSV371 and WSSV445 promoters can be activated by LvlKKβ or LvlKKε in Drosophila S2 cells. Taken together, our results reveal that LvlKKβ and LvlKKε may participate in the regulation of shrimp AMPs and that WSSV may subvert the L. vannamei IKK-NF-κB signaling pathway to facilitate viral gene expression.