A new duck genome reveals conserved and convergently evolved chromosome architectures of birds and mammals

BACKGROUND

Ducks have a typical avian karyotype that consists of macro- and microchromosomes, but a pair of much less differentiated ZW sex chromosomes compared to chickens. To elucidate the evolution of chromosome architectures between ducks and chickens, and between birds and mammals, we produced a nearly complete chromosomal assembly of a female Pekin duck by combining long-read sequencing and multiplatform scaffolding techniques.

RESULTS

A major improvement of genome assembly and annotation quality resulted from the successful resolution of lineage-specific propagated repeats that fragmented the previous Illumina-based assembly. We found that the duck topologically associated domains (TAD) are demarcated by putative binding sites of the insulator protein CTCF, housekeeping genes, or transitions of active/inactive chromatin compartments, indicating conserved mechanisms of spatial chromosome folding with mammals. There are extensive overlaps of TAD boundaries between duck and chicken, and also between the TAD boundaries and chromosome inversion breakpoints. This suggests strong natural selection pressure on maintaining regulatory domain integrity, or vulnerability of TAD boundaries to DNA double-strand breaks. The duck W chromosome retains 2.5-fold more genes relative to chicken. Similar to the independently evolved human Y chromosome, the duck W evolved massive dispersed palindromic structures, and a pattern of sequence divergence with the Z chromosome that reflects stepwise suppression of homologous recombination.

CONCLUSIONS

Our results provide novel insights into the conserved and convergently evolved chromosome features of birds and mammals, and also importantly add to the genomic resources for poultry studies.

A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia

We describe a new species of Polynesian sandpiper from Henderson Island, Prosobonia sauli sp. nov., based on multiple Holocene fossil bones collected during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands (1991–92). Prosobonia sauli is the only species of Prosobonia to be described from bone accumulations and extends the record of known extinct Polynesian sandpipers to four. It is readily differentiated from the extant Tuamotu Sandpiper P. parvirostris in several features of the legs and bill, implying ecological adaptations to different environments. The geographically nearest Prosobonia populations to Henderson Island were found on Mangareva, where it is now extinct. A previous record of a species of Prosobonia from Tubuai, Austral Islands, is here shown to belong to the Sanderling Calidris alba. Our analyses of newly sequenced genetic data, which include the mitochondrial genomes of P. parvirostris and the extinct Tahiti Sandpiper P. leucoptera, confidently resolve the position of Prosobonia as sister-taxon to turnstones and calidrine sandpipers. We present a hypothesis for the timing of divergence between species of Prosobonia and other scolopacid lineages. Our results further provide a framework to interpret the evolution of sedentary lineages within the normally highly migratory Scolopacidae.

Progressive Cactus is a multiple-genome aligner for the thousand-genome era

New genome assemblies have been arriving at a rapidly increasing pace, thanks to decreases in sequencing costs and improvements in third-generation sequencing technologies1-3. For example, the number of vertebrate genome assemblies currently in the NCBI (National Center for Biotechnology Information) database4 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 assemblies5 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. Cactus6, 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.

Development of a new dynamic foveated imager on wide-angle infra-red thermography system to improve local spatial resolution in EAST

A new dynamic foveated imager has been developed and commissioned on the wide-angle infra-red thermography system in the Experimental Advanced Superconducting Tokamak. This technique improves the local spatial resolution by a factor of 2 while maintaining the wide-angle view to ensure safety operation. Taking advantage of the new foveated imager, heat flux splitting under the application of resonant magnetic perturbation (RMP) coils has been clearly observed. The results indicate that the toroidal asymmetric power load pattern is closely related to the perturbation field induced by the RMP coils.

MiR-92 overexpression suppresses immune cell function in ovarian cancer via LATS2/YAP1/PD-L1 pathway

PURPOSE

Increasing evidence suggested that microRNA plays an important role in ovarian cancer. In this study, the role of miR-92 in ovarian cancer was investigated.

METHODS

In this study, miR-92 expression in clinical sample was evaluated, role of miR-92 was investigated in vitro, and underlying mechanism was investigated using Chip, co-IP, and western blot.

RESULTS

In this study, we show that miR-92 is overexpressed in ovarian cancer tissue compared with normal cancer tissue. Transfection of miR-92 increased proliferation of ovarian cancer cell, and increased migration capacity and colony formation were observed after miR-92 transfection; we found that expression of LATS2 was decreased by miR-92, and this was further confirmed by luciferase assay, which proved that miR-92 is targeting 3' of the endogenous LATS2 gene. Downregulation of LATS2 resulted in increased translocation of YAP1 and upregulation of PD-L1, which subsequently suppressed NK cell function and promoted T cell apoptosis. Moreover, co-transfection of YAP1-targeted shRNA could relieve miR-92-induced immune suppression effect. Mechanically, immunoprecipitation (IP) was used to show that LATS2 interacted with YAP1 and subsequently limited nuclear translocation of YAP1; chromatin immunoprecipitation (ChIP) was used to confirm that YAP1 could bind to enhancer region of PD-L1 to enhance transcription activity of PD-L1.

CONCLUSIONS

Our data revealed a novel mechanism which finally resulted in immune suppression in ovarian cancer.

Non-invasive and real-time proliferative activity estimation based on a quantitative radiomics approach for patients with acromegaly: a multicenter study

BACKGROUND

Proliferative activity prediction is important for determining individual treatment strategies for patients with acromegaly, and tumor proliferative activity is usually measured by the expression of Ki-67.

OBJECTIVE

This study aimed to assess the value of a magnetic resonance imaging (MRI)-based radiomics approach in predicting the Ki-67 index of acromegaly patients.

METHODS

A total of 138 patients with acromegaly were retrospectively reviewed and randomly assigned to primary and validation cohorts. Radiomics features were extracted from MR images, and then the elastic net and recursive feature elimination algorithms were applied to determine critical radiomics features for constructing a radiomics signature. Subsequently, multivariable logistic regression analysis was used to select the most informative clinical features, and a radiomics nomogram incorporating a radiomics signature and selected clinical features was constructed for individual predictions. Twenty-five acromegaly patients were enrolled for multicenter model validation.

RESULTS

Seventeen radiomics features were selected to construct a radiomics signature that achieved an area under the curve (AUC) value of 0.96 and 0.89 in the primary cohort and the validation cohort, respectively. A radiomics nomogram that incorporated the radiomics signature and eight selected clinical features was constructed and showed good discrimination and calibration, with an AUC of 0.94 in the primary cohort and 0.91 in the validation cohort. The radiomics signature in the multicenter validation achieved an accuracy of 88.2%. The analysis of the decision curve showed that the radiomics signature and radiomics nomogram were clinically useful for patients with acromegaly.

CONCLUSIONS

The radiomics signature developed in this study could aid neurosurgeons in predicting the Ki-67 index of patients with acromegaly and could contribute to non-invasive measurement of proliferative activity, affecting individual treatment strategies.

Linezolid for the treatment of extensively drug-resistant tuberculosis: a systematic review and meta-analysis

SETTING: Studies have shown that linezolid (LZD) can be used to treat extensively drug-resistant tuberculosis (XDR-TB).OBJECTIVE: To conduct a systematic review and meta-analysis to assess existing evidence concerning efficacy and safety of LZD for XDR-TB treatment.DESIGN: The MEDLINE@OVID, PubMed, EMBASE, the Cochrane Library, Clinical Trials, Sinomed, CMCI, CNKI, VIP and Wanfang databases were systematically searched for randomised controlled trials, cohort studies, case series or case reports on XDR-TB patients treated with LZD from January 2000 to December 2016. Summary estimates of the rate of sputum culture conversion, treatment success and adverse effects were calculated; data that could not be combined were summarised and described qualitatively. The combined results were examined for heterogeneity, sensitivity and publishing bias.RESULTS: Twenty-two original studies covering a total of 302 patients with XDR-TB fulfilled the inclusion criteria. Pooled estimates for sputum culture conversion and treatment success rates were respectively 93.2% and 67.4% in XDR-TB patients on LZD treatment. The pooled estimates for the rate of myelosuppression, peripheral neuropathy, optic neuritis and adverse reactions of the gastrointestinal tract were respectively 42.5%, 26.0%, 19.0% and 35.0%. Heterogeneity was mostly due to the initial dose of LZD (≤600 mg/d or >600 mg/d), as patients with a high initial dose of LZD were more likely to have myelosuppression (48.4% vs. 24.8%, P = 0.010) and adverse events of the gastrointestinal tract (41.3% vs.15.4%, P = 0.100).CONCLUSION: LZD appears to be effective for XDR-TB, but adverse events are common. An LZD dose of ≤600 mg/d as the initial dose for treating XDR-TB patients is recommended.

Evolutionary History, Genomic Adaptation to Toxic Diet, and Extinction of the Carolina Parakeet

As the only endemic neotropical parrot to have recently lived in the northern hemisphere, the Carolina parakeet (Conuropsis carolinensis) was an iconic North American bird. The last surviving specimen died in the Cincinnati Zoo in 1918 [1]. The cause of its extinction remains contentious: besides excessive mortality associated to habitat destruction and active hunting, their survival could have been negatively affected by its range having become increasingly patchy [2] or by the exposure to poultry pathogens [3, 4]. In addition, the Carolina parakeet showed a predilection for cockleburs, an herbaceous plant that contains a powerful toxin, carboxyatractyloside, or CAT [5], which did not seem to affect them but made the birds notoriously toxic to most predators [3]. To explore the demographic history of this bird, we generated the complete genomic sequence of a preserved specimen held in a private collection in Espinelves (Girona, Spain), as well as of a close extant relative, Aratinga solstitialis. We identified two non-synonymous genetic changes in two highly conserved proteins known to interact with CAT that could underlie a specific dietary adaptation to this toxin. Our genomic analyses did not reveal evidence of a dramatic past demographic decline in the Carolina parakeet; also, its genome did not exhibit the long runs of homozygosity that are signals of recent inbreeding and are typically found in endangered species. As such, our results suggest its extinction was an abrupt process and thus likely solely attributable to human causes.

Effects of thermal boundary condition on methane oxidation in landfill cover soil at different ambient temperatures

Microbial aerobic methane oxidation (MAMO) has been considered as an environmental-friendly method for mitigating methane emission from municipal landfill sites. Soil column has in a landfill cover under one-dimensional (1-D) condition. However, most of the published soil column tests failed to simulate 1-D heat transfer due to the use of thermal conductive boundary at the sidewall. In the present study, a heavily instrumented soil column was developed to quantify the effects of thermal boundary condition on the methane oxidation efficiency under different ambient temperatures in landfill cover soil. The sidewall of the soil column was thermally insulated to ensure 1-D heat transport as would have been typically expected in the field condition. Two soil column tests with and without thermal insulation were conducted at a range of controlled ambient temperatures from 15 to 30°C, for studying how soil moisture, matric suction, gas pressure, soil temperature and gas concentration evolve with MAMO. The test results reveal that ignoring thermal insulation in a soil column test would result in a greater loss of soil heat generation by MAMO and hence oxidation efficiency by up to 100% for the range of temperature considered. When the ambient temperature increased to 30°C (but less than the optimum temperature for MAMO), the MAMO efficiency increased abruptly at first but then decreased substantially with time, and this is likely due to the accumulation of biomass generated by MAMO.

Revision of a CHF correlation for PWR under low pressure conditions with only dimensionless parameters as independent variables

Accurate prediction of the critical heat flux (CHF) is one of the key tasks of PWR core design and safety assessment, for the maximal allowable heat flux in the reactor core is limited by CHF. Since CHF in rod bundle cannot be predicted analytically, up-to-date predictive approach is based on empirical correlations related to the local thermal-hydraulic conditions, geometry and power distribution. However, development of CHF correlation for PWR fuel assemblies under low pressure conditions (2–10 MPa) is constrained by limited amount of experimental data points, which builds up in statistics a typical problem of small sample amounts, but requiring simultaneously high prediction accuracy. In our previous study, stepwise regression method was applied to develop a dimensional, empirical CHF correlation for PWR under low pressure conditions, termed as the advanced low pressure CHF correlation (ALPC), which successfully solves the challenge of small sample problem. However, the ALPC correlation still uses dimensional independent variables with less physical meanings, which limits its physical interpretability. In the current study, stepwise regression method was used to develop a revised, dimensionless version of the ALPC CHF correlation. First, various dimensionless, two-phase thermal-hydraulic parameters that might influence CHF were selected as candidate independent variables. With stepwise regression, the form and coefficients of the revised CHF correlation were optimized in a dynamic manner. Compared to the current ALPC correlation, the revised version developed in this study possesses a similar simple form but a much higher prediction accuracy. Revision of the ALPC correlation demonstrates clearly the advantages of utilizing dimensionless parameters as independent variables in CHF correlation, which points out a new direction of developing rod-bundle CHF correlations for engineering purpose.

The characteristics of internet-based venue sex-seeking and mobility among money boys in Tianjin, China

OBJECTIVES

Internet-based venue sex-seeking is prevalent among money boys (MBs), as is a high degree of mobility, which is crucial for HIV transmission in key populations with high risks of HIV infection. However, correlation studies in MBs are scarce because of the secretive nature of this hard-to-reach subpopulation. We conducted this project to explore the characteristics of MBs.

METHODS

This survey was conducted from December 2014 to June 2015 in Tianjin; a total of 330 MBs were recruited by convenience sampling. Demographic and behavioural data were collected for analysis.

RESULTS

Among the investigated MBs, 38 (11.52%) were HIV positive, 147 (44.55%) reported using internet-based venues to seek sexual partners and 257 (77.88%) had travelled to two or more destinations in the past 6 months. Compared with non-internet-based venue-using MBs, internet-based venue-using MBs were more likely to have part-time employment as MBs, to have a longer duration of working in the sex trade, to engage in finger intercourse and to present a history of substance abuse and sexually transmitted infections. However, internet-based venue-using MBs were less likely to exhibit consistent condom usage and undergo HIV testing. Origin of residence data showed that most MBs were from northern China, with Tianjin, Beijing and Shanghai as the main travel destinations. Mobile MBs were characterized as a group who were fully engaged in the sex trade and frequently took part in sexual activities but had a weak sense of self-protection.

CONCLUSIONS

Internet-based venue sex-seeking and mobility are prevalent in MBs. Renewed efforts in internet-based health promotion and school-based primary health examination programmes may benefit more mobile and/or internet-based venue sex-seeking MBs.