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The slow-evolving invertebrate amphioxus has an irreplaceable role in advancing our understanding of the vertebrate origin and innovations. Here we resolve the nearly complete chromosomal genomes of three amphioxus species, one of which best recapitulates the 17 chordate ancestor linkage groups. We reconstruct the fusions, retention, or rearrangements between descendants of whole-genome duplications, which gave rise to the extant microchromosomes likely existed in the vertebrate ancestor. Similar to vertebrates, the amphioxus genome gradually establishes its three-dimensional chromatin architecture at the onset of zygotic activation and forms two topologically associated domains at the Hox gene cluster. We find that all three amphioxus species have ZW sex chromosomes with little sequence differentiation, and their putative sex-determining regions are nonhomologous to each other. Our results illuminate the unappreciated interspecific diversity and developmental dynamics of amphioxus genomes and provide high-quality references for understanding the mechanisms of chordate functional genome evolution.

Sex chromosomes are mostly conserved, but in some cases are variable within species. Varanids are known for conserved sex chromosomes, but there are differences in the size of the W chromosome among species representing varying stages of sex chromosome evolution. We tested for homology of the ZW sex chromosome system in varanids with size differences among four species from two lineages in Australia, the dwarf lineage Odatria and the sand goanna lineage Gouldii, with a combined genomic and cytogenetic approach. We found that while DNA sequences of the sex chromosomes are conserved, a mutation on an enlarged autosomal microchromosome is homologous with the W in some isolated populations of V. acanthurus and V. citrinus from the Odatria lineage. The enlarged microchromosome was unpaired in all individuals tested and is likely an unbalanced segmental duplication translocated from the W to another microchromosome. We also found evidence of an ancient balanced duplication that is also homologous to the W and to the telomeric region of chromosome 2. We conclude the most parsimonious explanation is that the duplicated region likely originated on chromosome 2. We also demonstrated that genes and related DNA sequences have likely originated on an autosome, translocated to the W, accumulated repeats and amplified on the W and then duplicated and translocated to another autosomal microchromosome. Given the role of these duplications as important evolutionary drivers of speciation in other taxa, our findings provide broader insight into the evolutionary pathway leading to rapid chromosomal and genic divergence of species.

Two multi-amine, metformin (MTM) and polyethyleneimine (PEI), were used to prepare separative layer of composite membrane through chemical deposition with tea polyphenols (Tph), an inexpensive mixture of nature polyphenols, on a hybrid polysulfone (Psf) membrane. The supporting layer was a blend membrane of Psf, coupling agent treated sepiolite and cetyltrimethylammonium bromide (CTAB). Sepiolite and the surfactant improved surface hydrophilicity of membrane. Pure water flux (PWF) of membranes was increased from 33.97 to 611.46 L m−2 h−1 bar−1. The optimum mass ratio for MTM to Tph and PEI to Tph were 9.4:1 and 2.4:1 in chemical deposition reaction, respectively. MTM-Tph (MT) surface was negative charged while PEI-Tph (PT) was positive charged. Monomer reactivity determined the thickness of functional layer. Both composite membranes showed dyes rejection capacity at 1 bar. PT layer was thicker than MT, so did its rejection for dyes. The rejection of PT for 5 dyes were all higher than 98% and remained at 99.3% and 98.6% in 200 h for Congo red (CR) and neutral red (NR). PT membrane displayed the potential in textile waste water treatment.

The slow-evolving invertebrate amphioxus has an irreplaceable role in advancing our understanding into the vertebrate origin and innovations. Here we resolve the nearly complete chromosomal genomes of three amphioxus species, one of which best recapitulates the 17 chordate ancestor linkage groups. We reconstruct the fusions, retention or rearrangements between descendants of whole genome duplications (WGDs), which gave rise to the extant microchromosomes likely existed in the vertebrate ancestor. Similar to vertebrates, the amphioxus genome gradually establishes its 3D chromatin architecture at the onset of zygotic activation, and forms two topologically associated domains at the Hox gene cluster. We find that all three amphioxus species have ZW sex chromosomes with little sequence differentiation, and their putative sex-determining regions are nonhomologous to each other. Our results illuminate the unappreciated interspecific diversity and developmental dynamics of amphioxus genomes, and provide high-quality references for understanding the mechanisms of chordate functional genome evolution.

Reptile sex determination is attracting much attention because the great diversity of sex-determination and dosage compensation mechanisms permits us to approach fundamental questions about sex chromosome turnover and evolution. However, reptile sex chromosome variation remains largely uncharacterized and no reptile master sex determination genes have yet been identified. Here we describe a powerful and cost-effective “chromosomics” approach, combining probes generated from the microdissected sex chromosomes with transcriptome sequencing to explore this diversity in non-model Australian reptiles with heteromorphic or cryptic sex chromosomes. We tested the pipeline on a turtle, a gecko, and a worm-lizard, and we also identified sequences located on sex chromosomes in a monitor lizard using linked-read sequencing. Genes identified on sex chromosomes were compared to the chicken genome to identify homologous regions among the four species. We identified candidate sex determining genes within these regions, including conserved vertebrate sex-determining genes pdgfa, pdgfra amh and wt1, and demonstrated their testis or ovary-specific expression. All four species showed gene-by-gene rather than chromosome-wide dosage compensation. Our results imply that reptile sex chromosomes originated by independent acquisition of sex-determining genes on different autosomes, as well as translocations between different ancestral macro- and micro-chromosomes. We discuss the evolutionary drivers of the slow differentiation, but rapid turnover, of reptile sex chromosomes.

Microcapsule of 500 nm was fabricated through non-agitation solution polymerization, used 5, 11, 17, 23-tetra-t-butyl- 25, 26, 27, 28-tetrakis(chlorocarbonyl-methoxy) calix [4] arene (C4C) and piperazine (PIP) with or without agitation. It was the amphiphilic self-assembly of C4C that made microcapsule the unique product for C4C/PIP couple in chloroform. Fourier transform infrared spectrometry (FTIR) and the X-ray photoelectron spectroscopy (XPS) proved the successful preparation of microcapsule. Transmission electron microscope (TEM) showed that microcapsules uniformly scattered in chloroform as a colorless dispersion. Absorption-C4C/PIP ratio curve indicated that the optimum ratio is 1:3 by ultraviolet–visible spectroscopy (UV–Vis). Microcapsule was almost uniform and intact at the optimum concentration of 3 × 10−4 mol L−1 under the optimum ratio of C4C/PIP. TEM and dynamic light scattering (DLS) illustrated that non-agitation solution polymerization is a better method to prepare a dispersion of microcapsules. This dispersion can extract heavy metal cations from their aqueous solution and fixed them over the interface of the two liquid phases through the formation of floccule layer. Inductively coupled plasma optical emission spectroscopy (ICP-OES) data showed that extraction efficiencies of Pb(II), Zn(II), Cu(II), and Ce(II) ions were 98.85%, 100.00%, 99.56%, and 98.97%, respectively. Dilute nitric acid can dissociate floccule layer and release cations into water, meanwhile, renewing the dispersion. The recovery ratio was 77.50%, 62.96%, and 68.42% for Pb(II), Cu(II), and Ce(II) ions, respectively. For Zn(II) ions, the recovery efficiency was more than 99.99%.

A co-polymer (SPAA6) of 5-sulfoanthranilic acid (5SAA) and e-caprolactam was used to prepare membrane through nonsolvent induced phase separation (NIPS) method. The micro-structure of membrane was adjusted by small molecules to improve mechanic strength and performance, involving 7 commercial ionic surfactant and a self-synthesized one, S20. S20 showed the best compatibility with SPAA6, which converted spherical phase into network of strip-like units in micro-structure of membrane. Meanwhile, average pore size of the membrane was narrowed from 4.271 nm to 3.391 nm, tested by BET method. Tensile strength of membrane was improved from 2.5 MPa to 2.9 MPa. Therefore, anionic dyes rejection and membrane stability were both improved. It actually demonstrated that molecular weight distribution of SPAA6 was crucial for micro-structure construction of membrane since S20 was the SPAA6 of low molecular weight. In blend solution filtration test, membrane MS2 (1:2 for S20:SPAA6) displayed 98.22% rejection to Congo Red (CR) acid and 96.18% NaCl permeation under 1 bar. It showed 80.18% rejection to chrome blue K (ABK) and 96.28% NaCl permeation. Both water permeance were higher than 3.5 L·m−2·h−1·bar. Membrane MS2 showed the potential of fractionation of dye and NaCl, which was promising in textile waste water treatment.

Egg-laying mammals (monotremes) are the only extant mammalian outgroup to therians (marsupial and eutherian animals) and provide key insights into mammalian evolution1,2. Here we generate and analyse reference genomes of the platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus), which represent the only two extant monotreme lineages. The nearly complete platypus genome assembly has anchored almost the entire genome onto chromosomes, markedly improving the genome continuity and gene annotation. Together with our echidna sequence, the genomes of the two species allow us to detect the ancestral and lineage-specific genomic changes that shape both monotreme and mammalian evolution. We provide evidence that the monotreme sex chromosome complex originated from an ancestral chromosome ring configuration. The formation of such a unique chromosome complex may have been facilitated by the unusually extensive interactions between the multi-X and multi-Y chromosomes that are shared by the autosomal homologues in humans. Further comparative genomic analyses unravel marked differences between monotremes and therians in haptoglobin genes, lactation genes and chemosensory receptor genes for smell and taste that underlie the ecological adaptation of monotremes., New reference genomes of the two extant monotreme lineages (platypus and echidna) reveal the ancestral and lineage-specific genomic changes that shape both monotreme and mammalian evolution.

BackgroundTilapias are one of the most farmed fishes that are coined as ‘aquatic chicken’ by the food industry. Like many other teleosts, Nile tilapia and blue tilapia exhibit very recent transition of sex chromosome systems since their divergence about 5 million years ago, making them a great model for elucidating the molecular and evolutionary mechanisms of sex chromosome turnovers. Studies into their sex-determining pathways are also critical for developing genetic sex control in aquaculture.ResultsWe report here the newly produced genomes of Nile tilapia and blue tilapia that integrate long-read sequencing and chromatin conformation data. The two nearly complete genomes have anchored over 97% of the sequences into linkage groups (LGs), and assembled majorities of complex repetitive regions including telomeres, centromeres and rDNA clusters. In particular, we inferred two episodes of repeat expansion at LG3 respectively in the ancestor of cichlids and that of tilapias. The consequential large heterochromatic region concentrated at one end of LG3 comprises tandem arrays of mRNA and small RNA genes, among which we have identified a candidate female determining gene Paics in blue tilapia. Paics show female-specific patterns of single-nucleotide variants, copy numbers and expression patterns in gonads during early gonadogenesis.ConclusionsOur work provide a very important genomic resource for functional studies of cichlids, and suggested that unequal distribution of repeat content that impacts the local recombination rate might make some chromosomes more likely to become sex chromosomes.