The study of the evolution of chromosomal number and structure has long been of interest to evolutionary biologists. However, this research has been hindered by the lack of chromosome-level genome ...assemblies for multiple species across phylogenetic lineages. Three recent studies from same research group have demonstrated the power of bioinformatic approaches in producing chromosome level genome assemblies and reconstructing the karyotypic history of birds.
As economic globalization progresses unceasingly, the financial activities of enterprises are increasingly complex, paralleled by a concomitant increase in the intricacy of tax laws and regulations. ...Consequently, the tax risks faced by enterprises are becoming more pronounced. To predict the financial status of enterprises, a logistic regression model is created by combining relevant financial indicators. Considering the large amount of enterprise financial sample data, a Lasso-Logistic regression model is constructed, and the ADMM algorithm optimizes the model to improve the model's prediction accuracy. Finally, after using the ROC curve to test the validity of the constructed financial index prediction model, the A-share listed companies in the advanced manufacturing industry are taken as the research object of empirical analysis to analyze the relationship between the impact of financial indexes on tax burden. The regression equation for the standardization of tax burden is tax risk = -0.02341+0.03572 VAT effective tax burden +0.15451 income tax effective tax burden +0.21118 current ratio -0.26875 total asset turnover +0.06574 current sales revenue +0.02432 current cost of goods sold +0.13681 gearing ratio + 0.23708 Fixed Assets Change Ratio - 0.26895 Asset Size. Based on the analysis results, this paper proposes three optimization strategies for tax burden.
This paper reviews the status of the research on industrial hydrogen production technology and development in China. The pros and cons of different hydrogen production technologies are compared. In ...addition, it is also conducted a comprehensive analysis of hydrogen production technology from economic and environmental aspects. Finally, the opportunities and challenges faced by the development of China’s hydrogen production technology are analyzed. In China, hydrogen production technology from fossil fuels such as coal and natural gas is relatively mature. Among them, hydrogen production by coal gasification and/or methane steam reforming have achieved large-scale applications. But its biggest problem is large carbon emissions, which does not meet China’s the development plan of "peaking carbon dioxide emissions and carbon neutrality." Hydrogen production technology through water electrolysis has many advantages, such as cleanness, pollution-free, and high purity of the hydrogen. However, it has the disadvantages of large power consumption and high hydrogen production cost. China has abundant renewable resources, but the technology for hydrogen production from renewable energy is still in its infancy and its development is not yet mature. Through comprehensive analysis, we believe that China should continue to develop new technologies while maintaining the advantages of traditional fossil fuel hydrogen production technologies. At the same time, China should also make full use of China’s remaining wind, light, electricity and biomass resources to develop green hydrogen production technologies such as electrohydrolysis. Through the above-mentioned various measures, it will effectively promote the transformation of China’s energy structure and realize the diversification of the hydrogen industry in the true sense.
Graphic Abstract
Equilibrium conformational properties of a ring polymer (named by ‘inner ring’) simultaneously concatenated with a varying number of outer rings in a ‘flower’-shaped polymer catenane are explored by ...molecular dynamics simulations. Two different cases have been considered. In Case I, the excluded volume interactions between the outer rings are absent in a polymer catenane, while they are present in Case II. Results demonstrate that, compared to an isolated ring polymer, size and shape properties of the same, inner ring in a polymer catenane can be greatly modified by the catenation topology in both Cases. It is concluded that the topological catenation can induce a swelling of the inner ring in a catenane compared to the same ring in isolation. Importantly, scaling relationships between the swelling degree, fsw, of the inner ring and number of the outer rings, n, have been established in both Case I and Case II, fsw=anα, where the prefactor a and scaling exponent α are all predominantly dependent on molecular-weight ratio of the inner to outer rings in catenane. Besides, swelling of inner ring in a catenane of Case II is more pronounced than the same inner ring in a catenane of Case I. The mean asphericity of the inner ring is slightly increased due to the catenation topology, while its mean prolateness is remarkably modified by the catenation topology. The inner ring in a catenane becomes more oblate, compared to the same ring in isolation, with increasing either number or molecular weight of the outer rings in the catenane. Profiles of the mean prolateness changes of the inner ring from those of the same isolated ring with respect to number of the outer rings are also mainly controlled by the molecular-weight ratio of the inner to outer rings.
•Ring polymer swells when it is simultaneously concatenated with a number of other ring polymers.•Ring polymer gets more aspherical and oblate when it is concatenated with more ring polymers.
Dendrobium officinale Kimura et Migo is a traditional Chinese orchid herb that has both ornamental value and a broad range of therapeutic effects. Here, we report the first de novo assembled 1.35 Gb ...genome se- quences for D. officinale by combining the second-generation Illumina Hiseq 2000 and third-generation PacBio sequencing technologies. We found that orchids have a complete inflorescence gene set and have some specific inflorescence genes. We observed gene expansion in gene families related to fungus symbiosis and drought resistance. We analyzed biosynthesis pathways of medicinal components of D. officinale and found extensive duplication of SPS and SuSy genes, which are related to polysaccharide generation, and that the pathway of D. officinale alkaloid synthesis could be extended to generate 16- epivellosimine. The D. officinale genome assembly demonstrates a new approach to deciphering large complex genomes and, as an important orchid species and a traditional Chinese medicine, the D. officinale genome will facilitate future research on the evolution of orchid plants, as well as the study of medicinal components and potential genetic breeding of the dendrobe.
Global climate fluctuations have significantly influenced the distribution and abundance of biodiversity 1. During unfavorable glacial periods, many species experienced range contraction and ...fragmentation, expanding again during interglacials 2–4. An understanding of the evolutionary consequences of both historical and ongoing climate changes requires knowledge of the temporal dynamics of population numbers during such climate cycles. Variation in abundance should have left clear signatures in the patterns of intraspecific genetic variation in extant species, from which historical effective population sizes (Ne) can be estimated 3. We analyzed whole-genome sequences of 38 avian species in a pairwise sequentially Markovian coalescent (PSMC, 5) framework to quantitatively reveal changes in Ne from approximately 10 million to 10 thousand years ago. Significant fluctuations in Ne over time were evident for most species. The most pronounced pattern observed in many species was a severe reduction in Ne coinciding with the beginning of the last glacial period (LGP). Among species, Ne varied by at least three orders of magnitude, exceeding 1 million in the most abundant species. Several species on the IUCN Red List of Threatened Species showed long-term reduction in population size, predating recent declines. We conclude that cycles of population expansions and contractions have been a common feature of many bird species during the Quaternary period, likely coinciding with climate cycles. Population size reduction should have increased the risk of extinction but may also have promoted speciation. Species that have experienced long-term declines may be especially vulnerable to recent anthropogenic threats.
•Cyclic Ne changes have been a common feature of many birds during the Quaternary period•Severe reductions in Ne coincide with the beginning of the last glacial period•Species with long-term decline in Ne may be especially vulnerable to recent threats
The abundance and distribution of life on Earth has been critically influenced by global climatic oscillations. Nadachowska-Brzyska et al. show that many bird species experienced cycles of population contractions and expansion during the Quaternary period, and that severe declines in effective population size often coincided with the beginning of the last glacial period.
Ruminants are the only extant mammalian group possessing bony (osseous) headgear. We obtained 221 transcriptomes from bovids and cervids and sequenced three genomes representing the only two pecoran ...lineages that convergently lack headgear. Comparative analyses reveal that bovid horns and cervid antlers share similar gene expression profiles and a common cellular basis developed from neural crest stem cells. The rapid regenerative properties of antler tissue involve exploitation of oncogenetic pathways, and at the same time some tumor suppressor genes are under strong selection in deer. These results provide insights into the evolutionary origin of ruminant headgear as well as mammalian organ regeneration and oncogenesis.
New genome assemblies have been arriving at a rapidly increasing pace, thanks to decreases in sequencing costs and improvements in third-generation sequencing technologies
. For example, the number ...of vertebrate genome assemblies currently in the NCBI (National Center for Biotechnology Information) database
increased by more than 50% to 1,485 assemblies in the year from July 2018 to July 2019. In addition to this influx of assemblies from different species, new human de novo assemblies
are being produced, which enable the analysis of not only small polymorphisms, but also complex, large-scale structural differences between human individuals and haplotypes. This coming era and its unprecedented amount of data offer the opportunity to uncover many insights into genome evolution but also present challenges in how to adapt current analysis methods to meet the increased scale. Cactus
, a reference-free multiple genome alignment program, has been shown to be highly accurate, but the existing implementation scales poorly with increasing numbers of genomes, and struggles in regions of highly duplicated sequences. Here we describe progressive extensions to Cactus to create Progressive Cactus, which enables the reference-free alignment of tens to thousands of large vertebrate genomes while maintaining high alignment quality. We describe results from an alignment of more than 600 amniote genomes, which is to our knowledge the largest multiple vertebrate genome alignment created so far.
Inquiline ants are highly specialized and obligate social parasites that infiltrate and exploit colonies of closely related species. They have evolved many times convergently, are often ...evolutionarily young lineages, and are almost invariably rare. Focusing on the leaf-cutting ant genus Acromyrmex, we compared genomes of three inquiline social parasites with their free-living, closely-related hosts. The social parasite genomes show distinct signatures of erosion compared to the host lineages, as a consequence of relaxed selective constraints on traits associated with cooperative ant colony life and of inquilines having very small effective population sizes. We find parallel gene losses, particularly in olfactory receptors, consistent with inquiline species having highly reduced social behavioral repertoires. Many of the genomic changes that we uncover resemble those observed in the genomes of obligate non-social parasites and intracellular endosymbionts that branched off into highly specialized, host-dependent niches.
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