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Hypertrophic scarring is a fibro-proliferative disorder caused by abnormal cutaneous wound healing. Circulating metabolites and the gut microbiome may be involved in the formation of these scars, but high-quality evidence of causality is lacking. To assess whether circulating metabolites and the gut microbiome contain genetically predicted modifiable risk factors for hypertrophic scar formation. Two-sample Mendelian randomization (MR) was performed using MR-Egger, inverse-variance weighting (IVW), Mendelian Randomization Pleiotropy RESidual Sum and Outlier, maximum likelihood, and weighted median methods. Based on the genome-wide significance level, genetically predicted uridine (P = 0.015, odds ratio [OR] = 1903.514, 95% confidence interval [CI] 4.280–846,616.433) and isovalerylcarnitine (P = 0.039, OR = 7.765, 95% CI 1.106–54.512) were positively correlated with hypertrophic scar risk, while N-acetylalanine (P = 0.013, OR = 7.98E-10, 95% CI 5.19E-17–0.012) and glycochenodeoxycholate (P = 0.021, OR = 0.021 95% CI 0.003–0.628) were negatively correlated. Gastranaerophilales and two unknown gut microbe species (P = 0.031, OR = 0.378, 95% CI 0.156–0.914) were associated with an decreased risk of hypertrophic scarring. Circulating metabolites and gut microbiome components may have either positive or negative causal effects on hypertrophic scar formation. The study provides new insights into strategies for diagnosing and limiting hypertrophic scarring. [ABSTRACT FROM AUTHOR]

Understanding the roles of genetic divergence and phenotypic plasticity in adaptation is central to evolutionary biology and important for assessing adaptive potential of species under climate change. Analysis of a chromosome-level assembly and resequencing of individuals across wide latitude distribution in the estuarine oyster (Crassostrea ariakensis) revealed unexpectedly low genomic diversity and population structures shaped by historical glaciation, geological events and oceanographic forces. Strong selection signals were detected in genes responding to temperature and salinity stress, especially of the expanded solute carrier families, highlighting the importance of gene expansion in environmental adaptation. Genes exhibiting high plasticity showed strong selection in upstream regulatory regions that modulate transcription, indicating selection favoring plasticity. Our findings suggest that genomic variation and population structure in marine bivalves are heavily influenced by climate history and physical forces, and gene expansion and selection may enhance phenotypic plasticity that is critical for the adaptation to rapidly changing environments. Ao Li, He Dai, and Ximing Guo et al. present a high-quality genome from the estuarine oyster, Crassostrea ariakensis. They highlight the climate impact on population divergence, a suite of genes likely important for adaptation to environments of different temperatures and salinities, and provide further insight into the evolution of this species. [ABSTRACT FROM AUTHOR]

As an important and complex trait, inflorescence length (IL) of soybean [Glycine max (L.) Merr.] significantly affected seed yields. Therefore, elucidating molecular basis of inflorescence architecture, especially for IL, was important for improving soybean yield potentials. Longer IL meaned to have more pod and seed in soybean. Hence, increasing IL and improving yield are targets for soybean breeding. In this study, a association panel, comprising 283 diverse samples, was used to dissect the genetic basis of IL based on genome-wide association analysis (GWAS) and haplotype analysis. GWAS and haplotype analysis were conducted through high-throughout single-nucleotide polymorphisms (SNP) developed by SLAF-seq methodology. A total of 39, 057 SNPs (minor allele frequency ≥ 0.2 and missing data ≤ 10%) were utilized to evaluate linkage disequilibrium (LD) level in the tested association panel. A total of 30 association signals were identified to be associated with IL via GWAS. Among them, 13 SNPs were novel, and another 17 SNPs were overlapped or located near the linked regions of known quantitative trait nucleotide (QTN) with soybean seed yield or yield component. The functional genes, located in the 200-kb genomic region of each peak SNP, were considered as candidate genes, such as the cell division/ elongation, specific enzymes, and signaling or transport of specific proteins. These genes have been reported to participant in the regulation of IL. Ten typical long-IL lines and ten typical short-IL lines were re-sequencing, and then, six SNPs from five genes were obtained based on candidate gene-based association. In addition, 42 haplotypes were defined based on haplotype analysis. Of them, 11 haplotypes were found to regulate long IL (> 14 mm) in soybean. The identified 30 QTN with beneficial alleles and their candidate genes might be valuable for dissecting the molecular mechanisms of IL and further improving the yield potential of soybean. [ABSTRACT FROM AUTHOR]

Key message: Association analysis techniques were used to identify and verify twelve single nucleotide polymorphisms (SNPs) associated with Fusarium graminearum resistance. Two novel candidate genes were obtained.Abstract: Fusarium graminearum causes seed and root rot and seedling damping-off of soybean, leading to severe yield loss. Presently, the genetic basis of resistance to F. graminearum is elucidated in only four soybean accessions, which is not sufficient for resistance improvement. The objective of the present study was to identify the genome-wide genetic architecture of resistance to F. graminearum in landraces and cultivated soybeans based on a growth room evaluation. The resistance levels of 314 diverse accessions were tested, and 22,888 single nucleotide polymorphisms (SNPs) with a minor allele frequency of > 0.05 were developed using the specific-locus amplified fragment sequencing (SLAF-seq) approach. Twelve SNPs were identified as associated with F. graminearum resistance, and these SNPs were located at 12 genomic regions on eight chromosomes (Chr.) and could explain 5.53-14.71% of the observed phenotypic variation. One SNP, rs9479021, located on Chr.6, overlapped with qRfg_Gm06, the known QTL for resistance to F. graminearum. The other SNPs were novel and associated with resistance to F. graminearum. Nine novel candidate genes were predicted to contribute to resistance to F. graminearum according to the haplotype and transcript abundance analysis of the candidate genes. The identified markers and resistant cultivars are valuable for the improvement of resistance to F. graminearum. [ABSTRACT FROM AUTHOR]

To understand the genetic basis that underlies the phenotypic divergence between human and non-human primates, we screened a total of 7176 protein-coding genes expressed in the human brain and compared them with the chimpanzee orthologs to identify genes that show evidence of rapid evolution in the human lineage. Our results showed that the nonsynonymous/synonymous substitution (KaKs) ratio for genes expressed in the brain of human and chimpanzee is 0.3854, suggesting that the brain-expressed genes are under functional constraint. The X-linked human brain-expressed genes evolved more rapidly than autosomal ones. We further dissected the molecular evolutionary patterns of 34 candidate genes by sequencing representative primate species to identify lineage-specific adaptive evolution. Fifteen out of the 34 candidate genes showed evidence of positive Darwinian selection in human and/or chimpanzee lineages. These genes are predicted to play diverse functional roles in embryonic development, spermatogenesis and male fertility, signal transduction, sensory nociception, and neural function. This study together with others demonstrated the usefulness and power of phylogenetic comparison of multiple closely related species in detecting lineage-specific adaptive evolution, and the identification of the positively selected brain-expressed genes may add new knowledge to the understanding of molecular mechanism of human origin. [ABSTRACT FROM AUTHOR]

The origin of new structures and functions is an important process in evolution. In the past decades, we have obtained some preliminary knowledge of the origin and evolution of new genes. However, as the basic unit of genes, the origin and evolution of exons remain unclear. Because young exons retain the footprints of origination, they can be good materials for studying origin and evolution of new exons. In this paper, we report two young exons in a zinc finger protein gene of rodents. Since they are unique sequences in mouse and eat genome and no homologous sequences were found in the orthologous genes of human and pig, the young exons might originate afar the divergence of primates and rodents through exonization of intronic sequences. Strong positive selection was detected in the new exons between mouse and eat, suggesting that these exons have undergone significant functional divergence after the separation of the two species. On the other hand, population genetics data of mouse demonstrate that the new exons have been subject to functional constraint, indicating an important function of the new exons in mouse. Functional analyses suggest that these new exons encode a nuclear localization signal peptide, which may mediate new ways of nuclear protein transport. To our knowledge, this is the first example of the origin and evolution of young exons. [ABSTRACT FROM AUTHOR]

We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms (SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds (a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines-in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100?kilobases. [ABSTRACT FROM AUTHOR]

To find unknown protein-coding genes, annotation pipelines use a combination of ab initio gene prediction and similarity to experimentally confirmed genes or proteins. Here, we show that although the ab initio predictions have an intrinsically high false-positive rate, they also have a consistently low false-negative rate. The incorporation of similarity information is meant to reduce the false-positive rate, but in doing so it increases the false-negative rate. The crucial variable is gene size (including introns) - genes of the most extreme sizes, especially very large genes, are most likely to be incorrectly predicted. [ABSTRACT FROM AUTHOR]

Arising from: Y. Okazaki et al. 420, 563-573 (2002); Okazaki et al. replyOkazaki et al. have argued that as many as 15,815 of 33,409 non-redundant mouse complementary DNAs may represent functional RNA genes, on the basis of their findings that some of these cDNAs are confirmed by expressed sequence tagging and are found near CpG islands or polyadenylation signals-although many are expressed at such low levels that they could not be detected by microarray analysis. We show here that conservation of these‘non-coding’cDNAs in rats or humans is no better than in an evolutionarily neutral control. Our results indicate that they are either non-functional or, if they are functional, are specific to a given species. [ABSTRACT FROM AUTHOR]

The Pacific white shrimp Litopenaeus vannamei is the dominant crustacean species in global seafood mariculture. Understanding the genome and genetic architecture is useful for deciphering complex traits and accelerating the breeding program in shrimp. In this study, a genome survey was conducted and a high-density linkage map was constructed using a next-generation sequencing approach. The genome survey was used to identify preliminary genome characteristics and to generate a rough reference for linkage map construction. De novo SNP discovery resulted in 25,140 polymorphic markers. A total of 6,359 high-quality markers were selected for linkage map construction based on marker coverage among individuals and read depths. For the linkage map, a total of 6,146 markers spanning 4,271.43 cM were mapped to 44 sex-averaged linkage groups, with an average marker distance of 0.7 cM. An integration analysis linked 5,885 genome scaffolds and 1,504 BAC clones to the linkage map. Based on the high-density linkage map, several QTLs for body weight and body length were detected. This high-density genetic linkage map reveals basic genomic architecture and will be useful for comparative genomics research, genome assembly and genetic improvement of L. vannamei and other penaeid shrimp species. [ABSTRACT FROM AUTHOR]

Nautilus is the sole surviving externally shelled cephalopod from the Palaeozoic. It is unique within cephalopod genealogy and critical to understanding the evolutionary novelties of cephalopods. Here, we present a complete Nautilus pompilius genome as a fundamental genomic reference on cephalopod innovations, such as the pinhole eye and biomineralization. Nautilus shows a compact, minimalist genome with few encoding genes and slow evolutionary rates in both non-coding and coding regions among known cephalopods. Importantly, multiple genomic innovations including gene losses, independent contraction and expansion of specific gene families and their associated regulatory networks likely moulded the evolution of the nautilus pinhole eye. The conserved molluscan biomineralization toolkit and lineage-specific repetitive low-complexity domains are essential to the construction of the nautilus shell. The nautilus genome constitutes a valuable resource for reconstructing the evolutionary scenarios and genomic innovations that shape the extant cephalopods.