Mudskipper genomes provide insights into the terrestrial adaptation of amphibious fishes

Mudskippers are amphibious fishes that have developed morphological and physiological adaptations to match their unique lifestyles. Here we perform whole-genome sequencing of four representative mudskippers to elucidate the molecular mechanisms underlying these adaptations. We discover an expansion of innate immune system genes in the mudskippers that may provide defence against terrestrial pathogens. Several genes of the ammonia excretion pathway in the gills have experienced positive selection, suggesting their important roles in mudskippers’ tolerance to environmental ammonia. Some vision-related genes are differentially lost or mutated, illustrating genomic changes associated with aerial vision. Transcriptomic analyses of mudskippers exposed to air highlight regulatory pathways that are up- or down-regulated in response to hypoxia. The present study provides a valuable resource for understanding the molecular mechanisms underlying water-to-land transition of vertebrates

Association between actual weight status, perceived weight and depressive, anxious symptoms in Chinese adolescents: a cross-sectional study

<p>Abstract</p> <p>Backgroud</p> <p>The purpose of this study was to describe actual measured weight and perceived weight and to explore associations with depressive, anxiety symptoms in school adolescents in China.</p> <p>Methods</p> <p>A sample of 1144 Chinese adolescents was randomly selected from four schools in Wuhan, China, including 665 boys and 479 girls with ages ranging between 10 and 17 years. Actual measured weight and height and perceived weight status were compared to anxiety and depressive symptoms measured using the revised Self-Rating Anxiety Scale and Children's Depression Inventory. A general linear model was used to compare differences in psychological symptoms among the teenagers with different measured and perceived weights.</p> <p>Results</p> <p>When compared with standardized weight tables (WHO age- and gender-specific body mass index (BMI) cutoffs (2007 reference)), girls were more likely to misperceive themselves as overweight, whereas more boys misclassified their weight status as underweight. The adolescents who perceived themselves as overweight were more likely to experience depressive and anxiety symptoms (except girls) than those who perceived themselves as normal and/or underweight. However, no significant association was found between depressive and anxiety symptoms actual measured weight status.</p> <p>Conclusions</p> <p>Perceived weight status, but not the actual weight status, was associated with psychological symptoms.</p

Architecture and quantitative assessment of channeled clastic deposits, Shihezi sandstone (Lower Permian), Ordos Basin, China

Lower Permian Shihezi sandstone in Ordos Basin is the largest gas reservoir in China. Architecture elements of channel, overbank and floodplain facies of braided channel deposits were identified through an outcrops survey, and their proportion of channel facies have been quantitatively estimated from well logging. Characteristics of architecture elements, such as sand thickness, bounding surfaces and lithofacies were investigated through outcrops and core. Petrology of Shihezi sandstone has also been studied in detail. Analysis on sandstone components shows that monocrystalline quartz with approximately 76% bulk volume, and lithic up to 5%–45% bulk volume, are the two main components. Litharenite and lithic quartz sandstone are the main rock types. Compaction is concluded by former researchers as the control factor of low permeability. Examination through thin section reveals that secondary pores developed well in coarse sand. Inter-granular dissolution is included as the positive effect to increasing porosity, and is concluded as the control factor to the generation of net pay. Scale of coarse grained channel fills and channel bar sandstone bodies are quantitatively estimated. Strike-oriented, dip-oriented, and vertical distribution of channel fills and channel bar sandstone bodies have been investigated. The geometry of sand bodies can be depicted as an elongated lens. Subsurface mapping reveals that channel sandstone bodies distribute widely from both lateral and longitudinal cross section profiles, and are poorly connected

Connotations of scientific development of giant gas fields in China

A giant gas field refers to a gas field with proved geological reserves of natural gas more than 30 billion cubic meters, peak annual output of natural gas more than 1 billion cubic meters, and a certain plateau period. It is an important foundation for the rapid growth of China's natural gas reserves and production and its long-term stable development in the future. And it is also the key to ensure the security of gas supply. By systematically analyzing the development practice of more than 260 gas fields at home and abroad and dissecting and simulating typical gas fields, this paper comprehensively studied the connotation, core technology and whole life cycle index system on the scientific development of giant gas fields. It is indicated that the scientific development connotation of giant gas fields consists of the following parts. First, the natural gas development concept with “water identification, control and treatment” as the technical system is put forward. That is to carry out “water-control development” in conventional gas fields and hydraulic fracturing development in unconventional gas fields. A reasonable gas production rate should be set according to the types and characteristics of gas reservoirs. Second, economic and social benefits of gas field development should be evaluated comprehensively to ensure its long-term stable production. Third, the suitable production stabilization mode shall be adopted according to the production characteristics of gas wells and the development characteristics of reservoirs. Fourth, the recoverable reserves of a gas field, the development laws of formation water and artificial water flooding, the ultimate recovery technological countermeasures of the gas field, the cost-effective stable period of the gas field should be determined based on the fine description of conventional and unconventional gas reservoirs in different stages, the development characteristics of gas reservoirs and the monitoring results of production performance. The core technologies in the scientific development of giant gas fields include large-scale optimization technology, scientific well arrangement technology, balanced production technology and deep potential tapping technology. Based on this, several parameters are selected comprehensively as the key indexes for the scientific development of giant gas fields, such as production rate, pressure drop, degree of reserves recovery and output per unit pressure drop, and the whole life cycle index systems for four types of gas reservoirs are established, i.e., high-pressure gas reservoirs, low-permeability and tight gas reservoirs, fractured–porous reservoirs, and shale gas reservoirs. In conclusion, the research results enrich and improve the theories of natural gas development geology and are conducive to guiding the scientific development of different-type giant gas fields, thus further promoting the rapid development of natural gas industry in China