Southeast Coastal Areas Of China Research Articles

Modeling multi-scale relationships between wilderness area changes and potential drivers: Evidence from the southeast coastal area of China

An understanding of the trends and causes of wilderness change is critical in supporting wilderness conservation. However, quantitative measurement of the driving mechanisms of wilderness area changes with incorporation of spatial heterogeneity remains a challenge. An integrated wilderness mapping method was employed in this study, with Fujian Province, one of China's first Ecological Civilization Pilot Areas, serving as a case study, to identify the recent spatial distribution and the land-use change matrix of wilderness area changes in the densely populated southeast coastal regions of China. We investigated the potential drivers of changes in wilderness areas from three perspectives: anthropogenic activities and socioeconomics, natural environment, and protected areas management policies, and captured spatial variations using a Multi-Scale Geographically Weighted Regression model (MGWR). The area and quality of wilderness areas showed a decreasing trend from 2000 to 2020, with area decreasing by an average 3.63% annually and wilderness degradation being especially severe from 2010 to 2020. The loss of wilderness areas is influenced by multiple drivers, and under the influence of spatial heterogeneity, different drivers on wilderness areas have a cross-scale spatial character. Human activities and economic development are dominant in driving wilderness degradation and can exert pressure at a large scale. Protected areas may mitigate wilderness loss in the region, but wilderness near protected areas may face greater threats. Natural factors such as vegetation, precipitation and elevation have ambivalent effects, and in some area’s climate change may interact with human activities to exacerbate wilderness loss. Compared with global regression and geographically weighted regression models, MGWR produces more realistic results in modeling the relationship between wilderness area changes and potential drivers. This study provides a new perspective for wilderness research, reveals the complex mechanisms of change in wilderness areas, and provides important guidance for global wilderness conservation efforts as well as a reference point for exploring the synergistic interaction between economic development and natural conservation in the densely populated southeast coastal regions of China.

Sequence identification and expression characterization of leptin in the spotted scat, Scatophagus argus.

Scatophagus argus is an important marine culture fish in South and South-East Asia, including Southeast coastal areas of China. Artificial propagation technology for S. argus is not optimum; thus further studies on its reproduction biology are required. Although previous studies have shown that leptin (Lep) can regulate fish reproduction, the role of lep genes in S. argus is unknown. Herein, in silico analysis showed that S. argus has two lep genes (lepa and lepb). Protein 3D-structure prediction showed that Lepa has four α-helices (similar to mammals), while Lepb only has three. Tissue distribution analysis showed that lepa is highly expressed in the liver, whereas lepb was not detected in any tissue. Notably, lepr was expressed in all tissues. Lepa mRNA expression levels in the liver and serum Lep, estradiol (E2) and vitellogenin (Vtg) levels of female fish were significantly higher in ovaries at stage IV than in ovaries at stage II. Serum E2 levels were significantly positively correlated with Vtg levels in female fish at different development stages, while serum E2 was not correlated with Lep levels. Consistently, in vitro incubation of the liver with E2 significantly up-regulated vtga, while it did not affect lepa expression. Recombinant Lep (10nM) significantly up-regulated chicken gonadotropin-releasing hormone (cGnRH/GnRH-II) in the hypothalamus and GnRH receptor (GnRHR) and luteinizing hormone beta (Lhb) in the pituitary. These results suggest that lepa regulates female reproduction in S. argus.

A Study on Guan Yu Culture in the Southeast Coastal Areas of China : Focusing on Fujian Dongshan

A Study on Guan Yu Culture in the Southeast Coastal Areas of China : Focusing on Fujian Dongshan

Genomic formation of Tibeto-Burman speaking populations in Guizhou, Southwest China

Sino-Tibetan is the most prominent language family in East Asia. Previous genetic studies mainly focused on the Tibetan and Han Chinese populations. However, due to the sparse sampling, the genetic structure and admixture history of Tibeto-Burman-speaking populations in the low-altitude region of Southwest China still need to be clarified. We collected DNA from 157 individuals from four Tibeto-Burman-speaking groups from the Guizhou province in Southwest China. We genotyped the samples at about 700,000 genome-wide single nucleotide polymorphisms. Our results indicate that the genetic variation of the four Tibeto-Burman-speaking groups in Guizhou is at the intermediate position in the modern Tibetan-Tai-Kadai/Austronesian genetic cline. This suggests that the formation of Tibetan-Burman groups involved a large-scale gene flow from lowland southern Chinese. The southern ancestry could be further modelled as deriving from Vietnam’s Late Neolithic-related inland Southeast Asia agricultural populations and Taiwan’s Iron Age-related coastal rice-farming populations. Compared to the Tibeto-Burman speakers in the Tibetan-Yi Corridor reported previously, the Tibeto-Burman groups in the Guizhou region received additional gene flow from the southeast coastal area of China. We show a difference between the genetic profiles of the Tibeto-Burman speakers of the Tibetan-Yi Corridor and the Guizhou province. Vast mountain ranges and rivers in Southwest China may have decelerated the westward expansion of the southeast coastal East Asians. Our results demonstrate the complex genetic profile in the Guizhou region in Southwest China and support the multiple waves of human migration in the southern area of East Asia.

A novel cross-disciplinary approach for estimating spatio-temporal pattern and drivers of pollution transfer caused by industrial transfer processes

Food security is the basic requirement for human health and social stability. However, food pollution risk caused by economic development models, e.g., industrial transfer, is poorly understood. In this study, we developed and tested a point-area-domain cross-disciplinary approach to quantitatively estimate patterns and processes of soil and rice heavy metal (Pb, Hg and Cd) pollution risk caused by the fourth global industrial transfer process in CG Province of China. Our results indicate that the industrial transfer policy caused obvious cross-regional soil Pb, Hg and Cd pollution and industrial transfer. Industrial transfer process largely exacerbated rice Hg pollution risk in industrial transfer undertaking areas, mainly in the west (29.18%), periphery (28.38%) and south (25.88%) regions. The concentration increase in the west ranged from 0.0001 to 0.0775 mg/kg (mean±S.D. 0.00327 ± 0.00447, median 0.0026 mg/kg). The most important industries regarding rice Hg pollution in industrial transfer undertaking areas included special equipment (26.53%)>metal processing (11.93%)>communication equipment (11.25%)>chemical product (10.90%)> electrical machinery and equipment (9.59%). The pollution transfer was mainly attributed to environmental regulations, factor endowment and industrial structure. Our study highlights the importance for the integration of industrial transfer into food security and poverty reduction plans in the developing regions. Environmental implicationFood security is the basic requirement for human health and social stability. However, food pollution risk caused by economic development models, e.g., industrial transfer, is poorly understood. We developed and tested a point-area-domain cross-disciplinary approach to quantitatively estimate patterns and processes of soil and rice heavy metal pollution risk caused by the fourth global industrial transfer process. Our results suggest that industrial transfer process largely exacerbated soil and rice Hg pollution risk in the southeast coastal areas of China. Our study highlights the importance for the integration of industrial transfer into food security strategies in developing countries.

Time distribution pattern and spatial heterogeneity of hourly scale event-based extreme precipitation in China

Extreme precipitation occurs naturally in the form of “events,” and the spatio-temporal distribution pattern of event-based extreme precipitation is of great significance to flood disaster prevention and water resources protection. This study proposed the concept of hourly scale event-based extreme precipitation (HEEP), referring to a precipitation event with at least an hourly precipitation extreme (exceeding the 99th percentile threshold). Then we identified the dominant time distribution pattern (TDP), analyzed the seasonal proportion and distribution, and investigated the spatial distribution of three basic features (total frequency, amount, and duration) of HEEP from 2008 to 2017 in China and its nine major river basins. Results showed that over 90% of the areas in China were dominated by short-duration HEEP (S-HEEP, less than eight hours). While the rest areas were led by long-duration HEEP (L-HEEP, more than eight hours), mainly concentrated on the middle and lower reaches of the Yangtze River and southeast coastal areas of China. Areas dominated by S-HEEP were more than L-HEEP in different seasons except in winter. Three basic features of HEEP showed similar spatial distribution patterns of high in southeastern China and low in northwestern China, indicating HEEP frequently occurred in southeastern China with relatively large amounts and long duration. The concept of HEEP can provide new ideas for regional and global extreme precipitation research.

A multidimensional assessment and analysis of farmland fragmentation in the southeast coastal area of China

AbstractFarmland fragmentation is a typical feature of arable land use in the economies dominated by smallholder production mode, and scientific evaluation of farmland fragmentation is an effective and crucial process to find and solve problems. Farmland fragmentation, as a kind of long‐standing physiographic landscape and agricultural economic phenomenon under the comprehensive effect of “human‐land‐property rights”, not only contains the scale status and spatial distribution of cultivated patches but also is featured with farming and tenure right. However, the theoretical interpretation of the multidimensional characteristics of farmland fragmentation was insufficient, and it was rare to evaluate the farmland fragmentation based on plot scale. To this end, an evaluation framework of farmland fragmentation with four dimensions and 12 indicators was constructed in this paper. Moreover, regarding Minqing County located in China's southeast coast as a case, empirical research was thus conducted. The findings indicated that the physical properties of farmland patches were depicted through scale fragmentation. Spatial fragmentation represented the spatial distribution of farmland patches. Farming fragmentation revealed agricultural production and management differences while tenure fragmentation embodied the tenure rights segmentation induced by the land distribution system. Farmland fragmentation consolidation was an effective way to solve these issues, and some differential tactics should be conducted in accordance with the path of “zoning types–obstacle factors–consolidation directions–treatment measures”.

Assessment of Carbon Reduction Benefits of A/O-Gradient Constructed Wetland Renovation for Rural Wastewater Treatment in the Southeast Coastal Areas of China Based on Life Cycle Assessment: The Example of Xiamen Sanxiushan Village

The enhancement of carbon sequestration and emissions reduction has emerged as a primary concern in China’s rural regions. Nevertheless, numerous completed rural wastewater treatment facilities necessitate retrofitting due to suboptimal operational conditions. Consequently, evaluating the greenhouse gas (GHG) emissions impact and carbon reduction advantages of rural wastewater treatment facility retrofitting is essential. Existing research predominantly focuses on urban wastewater treatment plants, with minimal attention given to GHG emissions impact during the construction and demolition stages of wastewater treatment facilities. In this investigation, we developed a life cycle assessment (LCA)-based evaluation model to appraise the GHG emissions impact and carbon reduction benefits of retrofitting rural wastewater treatment facilities. We examined a renovation project in Sanxiushan Village, Xiamen City, Fujian Province, incorporating the integrated plant treatment technology of constructed wetlands. Our findings indicate that retrofitting offers significant advantages in terms of GHG emissions reduction, even when accounting for implicit GHG emissions. The establishment of supplementary terraced constructed wetlands and landscape greening can yield more substantial carbon reduction benefits. Moreover, we discovered that implicit GHG emissions during the construction stage can be mitigated by employing local, recycled, and low-carbon materials. Modifying vegetation community structure and prioritizing vegetation species selection can enhance the carbon storage capacity of plants, reducing overall life cycle GHG emissions and augmenting emissions reduction benefits. The evaluation model developed in this study can facilitate the promotion of low-carbon construction and operation of rural wastewater treatment facilities.

Sex-specific disparities of serum pepsinogen I in relation to body mass index.

The clinical significance of serum pepsinogen (PG) for screening gastric cancer has been a controversial topic. Serum PG I levels have been demonstrated to be correlated with age, sex, and the Helicobacter pylori (HP) infection. However, the underlying factors that influence serum PG I variations remain to be fully elucidated. We aimed to evaluate the impacts of sex and body mass index (BMI) on PG I in Chinese population. The cross-sectional study recruited 4,299 apparently healthy participants in Fujian Province. Serum PG levels were automatically measured using ELISA method. Serum H.pylori-IgG antibody was detected by the colloidal gold immunoassay. Clinical characteristics were obtained by questionnaire. Totally, 2,263 participants who had tests of serum PG and anti-HP IgG antibody were enrolled. Increased BMI and serum uric acid were observed in males with low PG I value (<70 μg/L). Multiple logistic regression showed the presence of overweight was the independent risk factor for male participants with low PG I level (odds ratio [OR] 1.519; p=0.017). However, the association was not found in females. Sex-specific association of serum low PG I with overweight was observed in the southeast coastal areas of China. Thus, effects of sexual dimorphism should not be ignored during the clinical utilization of serum PG I.

An In-Depth Assessment of the Drivers Changing China’s Crop Production Using an LMDI Decomposition Approach

Over the last decades, growing crop production across China has had far-reaching consequences for both the environment and human welfare. One of the emerging questions is “how to meet the growing food demand in China?” In essence, the consensus is that the best way forward would be to increase crop yield rather than further extend the current cropland area. However, assessing progress in crop production is challenging as it is driven by multiple factors. To date, there are no studies to determine how multiple factors affect the crop production increase, considering both intensive farming (using yield and multiple cropping index) and large-scale farming (using mean parcel size and number of parcels). Using the Logarithmic-Mean-Divisia-Index (LMDI) decomposition method combined with statistical data and land cover data (GlobeLand30), we assess the contribution of intensive farming and large-scale farming changes to crop production dynamics at the national and county scale. Despite a negative contribution from MPS (mean parcel size, ), national crop production increased due to positive contributions from yield (), MCI (multiple cropping index, ), as well as NP (number of parcels, ). This allowed China to meet the growing national crop demand. We further find that large differences across regions persist over time. For most counties, the increase in crop production is a consequence of improved yields. However, in the North China Plain, NP is another important factor leading to crop production improvement. On the other hand, regions witnessing a decrease in crop production (e.g., the southeast coastal area of China) were characterized by a remarkable decrease in yield and MCI. Our detailed analyses of crop production provide accurate estimates and therefore can guide policymakers in addressing food security issues. Specifically, besides stabilizing yield and maintaining the total NP, it would be advantageous for crop production to increase the mean parcel size and MCI through land consolidation and financial assistance for land transfer and advanced agricultural infrastructure.

Identifying carbon emission characteristics and carbon peak in China based on the perspective of regional clusters.

Global warming has endangered the natural ecosystem's balance, as well as human existence and development, and it is mostly caused by carbon dioxide. Identifying carbon emission characteristics and predicting carbon emission reasonably is helpful to provide indication for the effective design of emission reduction path. The most literature use a single prediction model; this paper predicts carbon emission using a number of strategies based on previous research. Considering the prediction accuracy, advantages, and disadvantages of each method, a new method combining autoregressive integrated moving average (ARIMA) model and NAR neural network (NAR-NN) is proposed; in addition, this paper attempts to explain the carbon emission characteristics and emission reduction paths of each region from the new perspective of clustering. First, the results show that China's carbon emission features can be divided into four categories: low-carbon demonstrative type, low-carbon potential type, high-carbon developed type, and high-carbon traditional type. Moreover, low-carbon demonstrative type includes merely Beijing and Shanghai, low-carbon potential type is distributed in the southeast coastal areas of China, the high-carbon developed type is mainly distributed in Northeast China, and the western region basically belongs to high-carbon traditional type. Second, ARIMA model and NAR-NN are the two best methods in terms of prediction effect, and the combined model has better prediction effect than the single model. Third, carbon emissions in most regions of China will increase in the next few years; the time of carbon peak in the east is earlier than that in the west regions of China. Beijing will probably be the first region in China to complete the carbon peak. Besides, there is a certain correlation between the carbon peak time and the type of carbon emission in each region.

Pollution mechanisms and photochemical effects of atmospheric HCHO in a coastal city of southeast China

Formaldehyde (HCHO) is a vital reactive carbonyl compound, which plays an important role in the photochemical process and atmospheric oxidation capacity. However, the current studies on the quantification of HCHO impacts on atmospheric photochemistry in southeast coastal areas of China with an obvious upward trend of ozone remain scarce and unclear, thus limiting the full understanding of formation mechanism and control strategy of photochemical pollution. Here, systematic field campaigns were conducted at a typical coastal urban site with good air quality to reveal HCHO mechanism and effects on O3 pollution mechanism during spring and autumn, when photochemical pollution events still frequently appeared. Positive Matrix Factorization model results showed that secondary photochemical formation made the largest contributions to HCHO (69 %) in this study. Based on the photochemical model, the HCHO loss rates in autumn were significantly higher than those in spring (P < 0.05), indicating that strong photochemical conditions constrain high HCHO levels in certain situations. HCHO mechanism increased the ROx concentrations by 36 %, and increased net O3 production rates by 31 %, manifesting that the reduction of HCHO and its precursors' emissions would effectively mitigate O3 pollution. Therefore, the pollution characteristics and photochemical effects of HCHO provided significant guidance for future photochemical pollution control in relatively clean areas.

Quantile regression analysis of time-space variation characteristics of tropical cyclones in the west North Pacific basin under global warming

ABSTRACT The enormous economic losses and casualties were caused by tropical cyclones in the southeast coastal areas of China every year. In order to understand the time-space variation characteristics of tropical cyclones (including intensity, minimum central atmosphere pressure, duration, and generation position) in the global and the western North Pacific basin, the monthly and interannual variation characteristics of tropical cyclones from 1949 to 2018 were analyzed by the quantile regression method and least square regression method. The results show that the global climate temperature and the annual maximum wind speed of tropical cyclones have a tendency to increase under different quantiles. While the maximum wind speed of tropical cyclones generated in the WNP basin basically decreases with the increase of years in El Niño, La Niña, and normal years under different quantiles. It is obvious that the interannual variation of the maximum wind speed of tropical cyclones is affected by the ENSO events. Similarly, minimum central atmospheric pressure, duration, and generation position of TCs from 1949 to 2018 are also analyzed in the present study. The results of this study can provide an effective reference for data analysis and trend prediction of tropical cyclones in the western North Pacific basin.

Identification of quantitative trait loci for growth-related traits in the blood clam (Tegillarca granosa)

The blood clam (Tegillarca granosa) is an economically important marine shellfish in the southeast coastal area of China. In T. granosa breeding practice, growth-related traits are most important phenotypic selection index. In order to increase the breeding efficiency, we used a previously published genetic linkage map of T. granosa to map quantitative trait loci (QTL) for growth-related traits in a single full sibling F1 family. Eight growth-related traits including shell length (SL), shell height (SH), shell width (SW), shell weight (Swi), shell umbo width (SUW), as well as outer ligament length (OLL), meat weight (MW) and total weight (TW) of T. granosa were measured for QTL mapping. The estimated phenotypic correlations between any 2 of the 8 growth-related traits were significant (P < 0.001). Twenty-nine QTL were identified for growth-related traits, including 13 QTL with the phenotypic variance of 4.20–15.63% in the female map and 16 QTL of 3.99%–14.58% in the male map. Thirteen amplification fragment length polymorphism (AFLP) markers were validated to closely link to seven QTL except the shell height. This is the first report of QTL mapping on growth-related traits in T. granosa. These QTL and their tightly linked markers present the initial step towards the goal of marker-assisted selection in T. granosa.

Epidemiological characteristics and spatio-temporal distribution patterns of human norovirus outbreaks in China, 2012-2018

Background and aim: Human norovirus are the leading cause of acute viral gastroenteritis worldwide. In China, the occurrence of norovirus outbreaks in different regions shows significant heterogeneity, while few study has focused on the spatial epidemiological characteristics of norovirus outbreaks. Thus, the aim of this study is to clarify the epidemiological characteristics and spatial distribution patterns of norovirus outbreaks. Methods: In China, according to the National Notifiable Disease Reporting System (NNDRS), 964 human norovirus outbreaks involving 50,548 cases in 26 provinces reported from 2012 to 2018 were analyzed in this study. Results: The outbreaks showed typical seasonality, with more outbreaks in winter and fewer in summer, and the total number of infected cases increased over time. The most common setting of norovirus outbreaks was school especially middle schools and primary schools with major transmission route of life-contact. More outbreaks occurred in southeast coastal areas of China and showed significant spatial aggregation. The highly clustered areas of norovirus outbreaks have expanded towards northeast over time. Conclusions: By identifying the epidemiological characteristics and high-risk areas of norovirus outbreaks, this study provides important scientific support for the development of preventive and control measures of norovirus outbreaks, which is conducive to the administrative management of high risk settings and reduction of disease burden in susceptible areas. Keywords: norovirus outbreak; epidemiological characteristics; spatio-temporal heterogeneity; spatio-temporal aggregation

Effects of Seawater Recharge on the Formation of Geothermal Resources in Coastal Areas and Their Mechanisms: A Case Study of Xiamen City, Fujian Province, China

The southeast coastal areas of China have abundant geothermal resources. Most especially, seawater-recharged geothermal systems in the coastal areas have large quantiles of recharge but suffer water salinization and low water temperature. Moreover, the geothermal water development in these areas may induce seawater intrusion. Understanding the genetic patterns of geothermal resources is significant for rational exploration and protection. This study analyzed the hydrochemical and environmental isotopic characteristics of geothermal water, groundwater, and surface water samples collected in the area with geothermal resources in Xiamen Province in the southeast coastal areas of China. Based on this, the recharge of geothermal water circulation and the genetic patterns of geothermal resources were revealed. The results of this study indicate that the geothermal water in mountainous areas and piedmonts in Xiamen is mainly recharged by rainfall infiltration. In contrast, the geothermal water in coastal areas in Xiamen is recharged by seawater mixing to different extents, as indicated by hydrochemical types, isotopic characteristics, and the C1-/Br- ratio of geothermal water. As revealed by the calculation results using the Cl− mixing model, 10 of 13 geothermal fields in Xiamen are recharged by seawater mixing, with a mixing ratio of up to 73.20% in the Pubian geothermal field. After being recharged by rainfall in the low mountainous areas, geothermal water migrates toward deep parts along NW-trending faults. Then, it converges with regional NE-trending deep faults to absorb heat conducted from deep parts to form deep geothermal reservoirs. The deep geothermal reservoirs were estimated to be 185–225°C using the silica-enthalpy mixing model. The geothermal water is mixed with cold water or seawater while rising along faults. The temperature of shallow geothermal reservoirs was estimated to be 71–145°C using SiO2 geothermometers.

Long-Term Performance of the Water Infiltration and Stability of Fill Side Slope against Wetting in Expressways

Different settlements and instabilities of unsaturated subgrade subjected to wetting have been paid increasing attention in the southeast coastal areas of China. However, the treatments are costly when they are used in engineering. In addition, the long-term performances of the treatments are unclear. Based on seepage theory for unsaturated soils, a novel subgrade using a capillary barrier was proposed in this study to reduce the different settlements and stabilities. Compared with previous studies, a capillary barrier was merely applied in the landfill. The long-term performance and feasibility of a capillary barrier applied in a tilted subgrade slope is worthy of study, particularly in humid climates. Using Geo-Studio, the feasibility was verified by comparing a conventional subgrade with a subgrade using a capillary barrier in southeast coastal areas in terms of pore-water pressure, water content, settlement, and the safety factor. The numerical results showed that the subgrade using a capillary barrier could provide significant improvements in the performance of reducing the impact of pore-water pressure distribution it suffered from, so as to lead to smaller different settlements. The vertical settlement of the pavement using a capillary barrier over a 1 year period was 1 cm. Compared with a conventional subgrade, the settlement fell by 94%, and the safely factor increased by 15% for the subgrade using the capillary barrier.

A Data-Driven Model for Spatial Shallow Landslide Probability of Occurrence Due to a Typhoon in Ningguo City, Anhui Province, China

From 9 to 11 August 2019, the southeast coastal areas of China were hit by Typhoon Lekima, which caused a large number of shallow landslides. The typhoon resulted in a maximum rainfall of 402 mm during 3 days in Ningguo City. In this study, satellite images were acquired before and after the rainfall and visual interpretation was used to identify 414 shallow landslides in Ningguo City, and a complete database of shallow landslides caused by the typhoon-induced rainfall in Ningguo City was created. Nine landslide-influencing factors were selected—elevation, slope, aspect, strata, distance to faults, distance to rivers, distance to roads, normalized vegetation difference index, and rainfall—and the relationships between the rainfall-induced landslide distribution and the influencing factors were analyzed. The Bayesian probability method was combined with a logistic regression model to establish a landslide probability map for the study area. The real probabilities of landslide occurrence in the study area under five different rainfall conditions were calculated, and probability maps of landslide occurrence were drawn. The results of this study provide a reference for disaster prevention and reduction of typhoon rainstorm landslides in the southeast coastal areas of China and a future basis for decision making by the Ningguo government departments before a typhoon rainstorm occurs.

Epidemiology of Klebsiella michiganensis Carrying Multidrug-Resistant IncHI5 Plasmids in the Southeast Coastal Area of China.

PurposeThis study aimed to explore the genomic characterization of multidrug-resistant IncHI5-carrying Klebsiella michiganensis strains and detailed genomic dissection of the IncHI5 plasmids.Materials and MethodsThrough whole-genome sequencing, the IncHI5 plasmid pK92-qnrS was obtained from a single clinical K. michiganensis isolate K92. All complete genomes of K. michiganensis strains from the Genome database of NCBI were collected and used to construct a maximum likelihood (ML) phylogenetic tree. The epidemiology and geographic distribution of all the K. michiganensis strains were conducted. An extensive comparison of the seven IncHI5 plasmids of K. michiganensis (one from this study, six from GenBank) was applied.ResultsThis study revealed that all K. michiganensis strains carrying IncHI5 plasmids from different clonal groups were located in the southeast coastal area of China. The backbone regions of IncHI5 plasmids were composed of replicon (repHI5B and repFIB), partition (parABC), and conjugal transfer (tra1/tra2). The main accessory resistant regions of IncHI5 could be divided into two categories, Tn1696-related region and Tn6535-related region. These seven IncHI5 plasmids carried multiple drug-resistance genes which were all mediated by the mobile genetic elements (MGEs).ConclusionData presented here help to provide an overall in-depth understanding of epidemiology and geographic distribution of IncHI5-carrying K. michiganensis and the structure and evolutionary history of IncHI5 plasmids.

Establishment of the Y-linked Dmrt1Y as the candidate sex determination gene in spotbanded scat (Selenotoca multifasciata)

Spotbanded scat (Selenotoca multifasciata) has become a valuable marine culturing fish species in the southeast coastal areas of China. Herein, sex-linked markers were developed in spotbanded scat to elucidate its genetic foundation of sex determination. Eighty-four (84) cultured spotbanded scat were randomly chosen and used to screen and test the sex-linked markers. The average weight of the female (249 g, n = 32) is significantly higher than that of the male (212 g, n = 52). The whole genome of a male spotbanded scat was sequenced using next-generation sequencing technology. Phylogenetic analysis showed that spotbanded scat diverged from its closely related species, spotted scat (Scatophagus argus) 13.1 million years ago.Three sex-linked markers (Marker-1, 2 and 3) were obtained in spotbanded scat. Marker-1 and 2 could only amplify 562 bp and 881 bp Dmrt1 specific bands in male fish, while there were no amplified bands in female fish. Marker-3 amplified a single band of 373 bp in all female, and double bands of 373 bp and specific 294 bp in male. Sequence analysis showed that the 294 and 373 bp are Dmrt1 homologous sequences. These results indicate that the spotbanded scat possesses XY sex-determination system (XX females, XY males). Two types of Dmrt1 cDNA sequences were cloned and named Dmrt1X and Dmrt1Y according to their locations on the X and Y chromosomes, respectively. The amino acid (aa) sequences coded by Dmrt1X (309 aa) and Dmrt1Y (305 aa) are highly similar (85.8%). Dmrt1Y mRNA is specifically expressed in testis, with no expression in the ovary. Hence, Dmrt1Y is male-specific and the candidate SD gene. Knowledge of genetic sex determination and the development of sex-linked markers in spotbanded scat, will promote artificial reproduction and breeding in aquaculture.