The genome and transcriptome of Japanese flounder provide insights into flatfish asymmetry

Flatfish have the most extreme asymmetric body morphology of vertebrates. During metamorphosis, one eye migrates to the contralateral side of the skull, and this migration is accompanied by extensive craniofacial transformations and simultaneous development of lopsided body pigmentation(1-5). The evolution of this developmental and physiological innovation remains enigmatic. Comparative genomics of two flatfish and transcriptomic analyses during metamorphosis point to a role for thyroid hormone and retinoic acid signaling, as well as phototransduction pathways. We demonstrate that retinoic acid is critical in establishing asymmetric pigmentation and, via cross-talk with thyroid hormones, in modulating eye migration. The unexpected expression of the visual opsins from the phototransduction pathway in the skin translates illumination differences and generates retinoic acid gradients that underlie the generation of asymmetry. Identifying the genetic underpinning of this unique developmental process answers long-standing questions about the evolutionary origin of asymmetry, but it also provides insight into the mechanisms that control body shape in vertebrates.National Natural Science Foundation of China [31130057, 31461163005, 31530078, 31472269, 31472262, 31472273]; State 863 High Technology R&D Project of China [2012AA092203, 2012AA10A408, 2012AA10A403-2]; Education and Research of Guangdong Province [2013B090800017]; Taishan Scholar Climb Project Fund of Shandong of China; Taishan Scholar Project Fund of Shandong of China for Young Scientists; Shanghai Universities First-class Disciplines Project of Fisheries; Program for Professor of Special Appointment (Eastern Scholar) at the Shanghai Institutions of Higher Learning; Shanghai Municipal Science, Special Project on the Integration of Industryinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/publishedVersio

Research on Heat Source Model and Weld Profile for Fiber Laser Welding of A304 Stainless Steel Thin Sheet

A heat source model is the key issue for laser welding simulation. The Gaussian heat source model is not suitable to match the actual laser weld profile accurately. Furthermore, fiber lasers are widely recognized to result in good-quality laser beam output, a narrower weld zone, less distortion, and high process efficiency, compared with other types of lasers (such as CO2, Nd : YAG, and diode lasers). At present, there are few heat source models for fiber laser welding. Most of researchers evaluate the weld profile only by the bead width and depth of penetration, which is not suitable for the laser keyhole welding nail-like profile. This paper reports an experimental study and FEA simulation of fiber laser butt welding on 1 mm thick A304 stainless steel. A new heat source model (cylindrical and cylindrical) is established to match the actual weld profile using Marc and Fortran software. Four bead geometry parameters (penetration depth, bead width, waist width, and depth of the waist) are used to compare between the experimental and simulation results. The results show that the heat source model of cylindrical and cylindrical can match the actual shape of the fiber laser welding feasibly. The error range of the penetration depth, bead width, waist width, and depth of the waist between experimental and simulation results is about 4.1 ± 1.6%, 2.9 ± 2.0%, 13.6 ± 7.4/%, and 18.3 ± 8.0%, respectively. In addition, it is found that the depth of penetration is more sensitive to laser power rather than bead width, waist width, and depth of the waist. Welding speed has a similar influence on the depth of penetration, weld width, waist width, and depth of the waist

Differences in DNA Methylation Between Disease-Resistant and Disease-Susceptible Chinese Tongue Sole (Cynoglossus semilaevis) Families

13 pages, 4 figures, supplemental material https://www.frontiersin.org/articles/10.3389/fgene.2019.00847/full#supplementary-materialDNA methylation, the most widely studied and most well-understood epigenetic modification, has been reported to play crucial roles in diverse processes. Although it has been found that DNA methylation can modulate the expression of immune-related genes in teleosts, a systemic analysis of epigenetic regulation on teleost immunity has rarely been performed. In this research, we employed whole-genome bisulfite sequencing to investigate the genome-wide DNA methylation profiles in select disease-resistant Cynoglossus semilaevis (DR-CS, family 14L006) and disease-susceptible C. semilaevis (DS-CS, family 14L104) against Vibrio harveyi infection. The results showed that following selective breeding, DR-CS had higher DNA methylation levels and different DNA methylation patterns, with 3,311 differentially methylated regions and 6,456 differentially methylated genes. Combining these data with the corresponding transcriptome data, we identified several immune-related genes that exhibited differential expression levels that were modulated by DNA methylation. Specifically, DNA methylation of tumor necrosis factor–like and lipopolysaccharide-binding protein-like was significantly correlated with their expression and significantly contributed to the disease resistance of the selected C. semilaevis family. In conclusion, we suggest that artificial selection for disease resistance in Chinese tongue sole causes changes in DNA methylation levels in important immune-related genes and that these epigenetic changes are potentially involved in multiple immune responses in Chinese tongue soleThis work was supported by the National Nature Science Foundation (31530078, 31461163005), the Taishan Scholar Project Fund of Shandong, China, the Applied Basic Research Project of Qingdao City (16-5-1-52-jch), the Natural Science Foundation of Shandong Province (ZR2019BC009), the Advanced Talents Foundation of QAU (6651118016), the “First Class Fishery Discipline” programme in Shandong ProvincePeer Reviewe