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Species with temperature-dependent sex determination (TSD) exhibit significant variation in the relationship between incubation temperatures and the sex ratios they produce, making this an ideal system for comparing processes producing variation above and below the species level. Furthermore, a deeper mechanistic understanding of TSD macro- and microevolution may help reveal the currently unknown adaptive significance of this variation or of TSD as a whole. Here, we probe these topics by examining the evolutionary dynamics of this sex-determining mechanism in turtles. Our ancestral state reconstructions of discrete patterns of TSD suggest that producing females at cool incubation temperatures is derived and potentially adaptive. However, the ecological irrelevance of these cool temperatures and a strong genetic correlation across the sex-ratio reaction norm in Chelydra serpentina both contradict this interpretation. We further find the phenotypic consequence of this genetic correlation in C. serpentina reflected across all turtle species, suggesting that a single genetic architecture underlies both intra- and interspecific variation in TSD in this clade. This correlated architecture can explain the macroevolutionary origin of discrete TSD patterns without assigning cool-temperature female production an adaptive value. However, this architecture may also constrain adaptive microevolutionary responses to ongoing climate change. [ABSTRACT FROM AUTHOR]

It is reported that the production of floral sexual phenotype in hexaploid monoecious persimmon (Diospyros kaki) is closely related to a pseudogene called OGI, and a short interspersed nuclear element (SINE)-like insertion (named Kali) in the OGI promoter leads to the gene silence. As a result, DNA methylation level of MeGI promoter determines the development of male or female flowers. However, the molecular mechanism in androecious D. kaki, which only bear male flowers, remains elusive. Here, real-time quantitative polymerase chain reaction (RT-qPCR), molecular cloning, and bisulfite PCR sequencing technique were carried out using 87 materials, including 56 androecious resources, 15 monoecious, and 16 gynoecious cultivars, to investigate the performance of OGI and MeGI on the specific androecious type of D. kaki in China. In conclusion, the Kali insertion was exactly located in the OGI promoter region, and the OGI gene and the Kali sequence were existing and conserved in androecious D. kaki. Meanwhile, we also demonstrated that the MeGI gene was widespread in our investigated samples. Ultimately, our result convincingly provided evidence that the low expression of OGI is probably ascribed to the presence of Kali displaying strong methylation in the OGI promoter, and low expression of MeGI, as well as high DNA methylation level, in the promoter was closely connected with the production of male flowers; this result was consistent with the monoecious persimmon model. Our findings provide predominant genetic aspects for investigation into androecious D. kaki, and future perfecting the sex-determining mechanisms in persimmon.

The article presents a study that analyzes the characteristics and the course of meiosis in six of araneomorph spiders belonging to the families of Lycosidae and Gnaphosidae coming from Israel, Turkey, and the Czech Republic. The study has determined that the number of diploid chromosomes and the sex-determining system of male species are Pardosa alacris and Pardosa saltans. It is noted that all species are having 10 autosomal bivalents other than two sex chromosomes during meiotic stages.

It is reported that the production of floral sexual phenotype in hexaploid monoecious persimmon (Diospyros kaki) is closely related to a pseudogene called OGI, and a short interspersed nuclear element (SINE)-like insertion (named Kali) in the OGI promoter leads to the gene silence. As a result, DNA methylation level of MeGI promoter determines the development of male or female flowers. However, the molecular mechanism in androecious D. kaki, which only bear male flowers, remains elusive. Here, real-time quantitative polymerase chain reaction (RT-qPCR), molecular cloning, and bisulfite PCR sequencing technique were carried out using 87 materials, including 56 androecious resources, 15 monoecious, and 16 gynoecious cultivars, to investigate the performance of OGI and MeGI on the specific androecious type of D. kaki in China. In conclusion, the Kali insertion was exactly located in the OGI promoter region, and the OGI gene and the Kali sequence were existing and conserved in androecious D. kaki. Meanwhile, we also demonstrated that the MeGI gene was widespread in our investigated samples. Ultimately, our result convincingly provided evidence that the low expression of OGI is probably ascribed to the presence of Kali displaying strong methylation in the OGI promoter, and low expression of MeGI, as well as high DNA methylation level, in the promoter was closely connected with the production of male flowers; this result was consistent with the monoecious persimmon model. Our findings provide predominant genetic aspects for investigation into androecious D. kaki, and future perfecting the sex-determining mechanisms in persimmon. [ABSTRACT FROM AUTHOR]

Background The barred knifejaw (Oplegnathus fasciatus), a member of the Oplegnathidae family of the Centrarchiformes, is a commercially important rocky reef fish native to East Asia. Oplegnathus fasciatus has become an important fishery resource for offshore cage aquaculture and fish stocking of marine ranching in China, Japan, and Korea. Recently, sexual dimorphism in growth with neo-sex chromosome and widespread biotic diseases in O. fasciatus have been increasing concern in the industry. However, adequate genome resources for gaining insight into sex-determining mechanisms and establishing genetically resistant breeding systems for O. fasciatus are lacking. Here, we analyzed the entire genome of a female O. fasciatus fish using long-read sequencing and Hi-C data to generate chromosome-length scaffolds and a highly contiguous genome assembly. Findings We assembled the O. fasciatus genome with a total of 245.0 Gb of raw reads that were generated using both Pacific Bioscience (PacBio) Sequel and Illumina HiSeq 2000 platforms. The final draft genome assembly was approximately 778.7 Mb, which reached a high level of continuity with a contig N50 of 2.1 Mb. The genome size was consistent with the estimated genome size (777.5 Mb) based on k -mer analysis. We combined Hi-C data with a draft genome assembly to generate chromosome-length scaffolds. Twenty-four scaffolds corresponding to the 24 chromosomes were assembled to a final size of 768.8 Mb with a contig N50 of 2.1 Mb and a scaffold N50 of 33.5 Mb using 1,372 contigs. The identified repeat sequences accounted for 33.9% of the entire genome, and 24 003 protein-coding genes with an average of 10.1 exons per gene were annotated using de novo methods, with RNA sequencing data and homologies to other teleosts. According to phylogenetic analysis using protein-coding genes, O. fasciatus is closely related to Larimichthys crocea, with O. fasciatus diverging from their common ancestor approximately 70.5–88.5 million years ago. Conclusions We generated a high-quality draft genome for O. fasciatus using long-read PacBio sequencing technology, which represents the first chromosome-level reference genome for Oplegnathidae species. Assembly of this genome assists research into fish sex-determining mechanisms and can serve as a resource for accelerating genome-assisted improvements in resistant breeding systems. [ABSTRACT FROM AUTHOR]