Research progress in relationships between freshwater bivalves and algae.

Eutrophication in freshwater has become increasingly severe around the world, resulting in phytoplankton overgrowth and benthic algae reduction. Bivalves can change the density, dominant species and community structure of phytoplankton, increase available light levels, and provide physical habitats and growth conditions for benthic algae. The nutritional composition, density, community structure, and toxin of algae affect the growth, feeding, digestion, metabolism, immunity of bivalves in return. Interactions of bivalves and algae and effects of environmental factors on these interactions need a synthesis of studies, when using bivalves as a biomanipulation tool to control eutrophication. Whether bivalves can effectively suppress phytoplankton and promote benthic algae is related to the collective filtration and excretion capacity determined by size, species, population densities of bivalves, the quantity and quality of algae, and environmental factors such as temperature, dissolved oxygen, pH, and hydrodynamic. Small scale bivalve biomanipulation experiments are mostly conducted in lakes, urban ponds, and reservoirs with some success, applying in the whole ecosystem should consider more questions such as natural conditions, selection and death or reproduction of bivalves, and ecological disturbances. This review provides new considerations for technical issues such as the sustainable cultivation of bivalves and the implementation of biomanipulation in eutrophic waters.

Information technology capability, open technological innovation and firm growth.

The aim of this paper is to investigate the effects of information technology (IT) capability on firm growth in the context of open technological innovation. The paper utilized a logical deductive approach to develop hypotheses and analytical frameworks, and collected empirical data from 256 Chinese new ventures. Regression analysis and structural equation models were used to test the hypotheses and analyze the data. The results showed that IT capability, including flexibility and integration of information technology, significantly influenced firm growth, and open technological innovation partially mediated the relationship between IT flexibility and firm growth, and significantly mediated the relationship between IT integration and firm growth. The paper's limitations include the cross-sectional design, limited sample size, and potential unobserved variables such as organizational learning that could affect the relationship between IT capability and firm growth. The research is the first to investigate the effects of IT capability on firm growth based on the mediation of open technological innovation in China, contributing to the literature on IT capability and providing insights for managerial practice in the sharing economy era.

Visualization and analysis of mapping knowledge domains for coronavirus research.

BACKGROUND: In recent years, many countries around the world have been threatened by COVs. The aim of this study was to better grasp developments and trends in research on coronavirus around the world and to promote theoretical research into their prevention and control. METHODS: Research on coronavirus was reviewed and analyzed using bibliometrics based on a total of 4860 publications collected from the Web of Science Core Collection database. Yearly quantitative distribution of literature, country/region distribution, organization distribution, main source journal distribution, subject category distribution, research knowledge bases, and research hotspots and frontiers were all analyzed, and CiteSpace and VOSviewer were used to plot knowledge domain maps, Excel was used to plot keyword strategy diagram. RESULTS: Coronavirus research could be roughly divided into 4 stages: preliminary development stage (before 2000), rapid growth stage (2000-2005), slow decline stage (2006-2011) and sustained growth stage (since 2012). America had taken the leading position in this field. The study of COVs involves many subject categories, mainly includes virology, veterinary sciences, biology, and immunology. At present, the key words in the field of coronavirus research were mainly divided into 6 major hot clusters, namely, the introduction and structure analysis of coronavirus, the research on the outbreak source and transmission of coronavirus, the research on the infection pathway of coronavirus in human body, the research on the pathogenesis of coronavirus, the research on the diagnosis and symptoms of coronavirus infection, and the research on the treatment of coronavirus. CONCLUSION: Coronavirus, which occurs all over the world, often causes huge casualties and economic losses, and poses a serious threat to the safe and stable operation of the social and economic system. Objective literature review and analysis can help scholars in related fields to deepen their overall understanding. And, there are several key issues that should be further explored in future research.

Molecular Cloning and Expression Analysis of Thyrotropin-Releasing Hormone, and Its Possible Role in Gonadal Differentiation in Rice Field eel Monopterus albus.

Rice field eel (Monopterus albus), a protogynous hermaphrodite fish, is a good model for the research of sex determination and gonadal differentiation in teleosts. In this study, we cloned the full-length cDNA sequence of trh, which encoded a predicted protein with 270 amino acids. Trh mainly expressed in the brain, followed by the ovary, testis, muscle and pituitary, and had low levels in other peripheral tissues. During natural sex reversal, trh mRNA expression levels exhibited a significant increase at the late intersexual stage in the hypothalamus. In the gonad, trh mRNA expression levels showed a trend of increase followed by decrease, and only increased significantly at the middle intersexual stage. No matter static incubation or intraperitoneal (IP) injection, TRH had no significant effect on trh and thyroid-stimulating hormone ßsubunit (tshß) mRNA expression levels, and serum T3, T4 and TRH release. After static incubation of ovarian fragments by TRH, the expression of gonadal soma derived factor (gsdf) was up-regulated significantly at both the doses of 10 and 100 nM. IP injection of TRH stimulated the expression of gsdf, and inhibited the expression of ovarian aromatase gene (cyp19a1a), accompanied by the increase of serum 11-KT levels. The results indicated that TRH may play a novel role in gonadal differentiation by the regulation of gonadal differentiation-related gene expression and sex steroid hormone secretion in rice field eel.

Identification and expression analysis of thyroid-stimulating hormone ß subunit, and effects of T3 on gonadal differentiation-related gene expression in rice field eel, Monopterus albus.

Thyroid-stimulating hormone (TSH) is an important glycoprotein in hypothalamic-pituitary-thyroid axis, which plays a crucial role in the synthesis and release of thyroid hormones in vertebrates. Rice field eel, Monopterus albus, a protogynous hermaphroditic fish, which undergoes sex reversal from a functional female to a male, is an ideal model to investigate the regulation of sex differentiation. In this study, we obtained the cDNA sequence of thyroid-stimulating hormone ß subunit (tshß) from rice field eel, which contained a complete open reading frame and encoded a putative protein of 151 amino acids. Multiple alignment of protein sequences showed that tshß was highly conserved in teleost. The tissue distribution indicated that tshß showed high expression in the pituitary, moderate expression in the brain region, gonad, intestine and liver, and low expression in other peripheral tissues. During natural sex reversal, the expression of tshß had no significant difference in the pituitary. Compared to that in the ovary, the expression of tshß increased significantly in the gonad at late intersexual and male stages. After treatment by different doses of triiodothyronine (T3) (1 µg/g, 10 µg/g and 100 µg/g body weight), serum T3 and free triiodothyronine (FT3) increased sharply, while the expression of tshß were inhibited significantly in the pituitary. Although T3 had no significant effect on the levels of serum E2, it stimulated the release of serum 11-KT at high-dose group. We also detected the effects of T3 on the expression of gonadal differentiation-related genes in rice field eel. T3 treatment inhibited the expression of foxl2, cyp19a1a and dax1, while stimulated the expression of sox9a1. These results indicate that TSH may be involved in sex differentiation, and THs may play roles in the regulation of male development and sex reversal in rice field eel.

Histopathology, antioxidant responses, transcriptome and gene expression analysis in triangle sail mussel Hyriopsis cumingii after bacterial infection.

Bacterial disease outbreaks in filter feeder bivalve Hyriopsis cumingii as water contamination become more frequent in the water ecosystem, especially in intensive aquaculture habitats. To characterize host-pathogen interactions between H. cumingii and bacterial infection, we investigated the effects of Stenotrophomonas maltophilia HOP3 and Aeromonas veronii GL1 on the antioxidant response, tissue invasion and transcriptome expression of H. cumingii by infectivity trials. We showed that bacterial infections resulted in tubular necrosis of the hepatopancreas and induced the acute immune response in H. cumingii. The transcriptomic study identified a total of 5957 differentially expressed genes (DEGs) after A. veronii challenge. These DEGs were implicated in 302 KEGG pathways, notably in Apoptosis, Phagosome and Lysosome. The results showed that the relative expressions of all six immune-related DEGs were effectively stimulated with A. veronii, accompanied by tissue differences. Overall, these findings will contribute to an analysis of the immune response of H. cumingii to bacterial infection at the transcriptomic level and its genomic resource for research.

The Bioaccumulation and Biodegradation of Testosterone by Chlorella vulgaris.

: In the present study, the accumulation and degradation of testosterone by Chlorella vulgaris were studied. The results showed that C. vulgaris has a significant ability to eliminate testosterone by bioaccumulation and biodegradation, and during the 96 h experimental period, the data demonstrated that the accumulation of testosterone followed a sigmoidal accumulation pattern. At the end of the experiment, the bioconcentration percentages of testosterone by C. vulgaris in the high-concentration group and the low-concentration group were 11.49 ± 2.78% and 40.10 ± 1.98%, respectively, and the biodegradation percentages of testosterone were 69.64 ± 4.33% and 42.48 ± 1.92%, respectively. The rate of biodegradation of testosterone by C. vulgaris mainly depended on the relative initial concentration of testosterone. When the relative initial concentration of testosterone increases, the degradation may gradually change from zero-order kinetics to second-order kinetics.

Physiological responses of Egeriadensa to high ammonium concentration and nitrogen deficiency.

High ammonia (i.e. the total of NH(3) and NH(4)(+)) concentration or nitrogen deficiency in water can exert stress on growth and health of many aquatic plants. To investigate the physiological impacts of high ammonia-N (NH(4)Cl) concentration and nitrogen deficiency on plant physiology, apical shoots of submerged macrophyte Egeriadensa were first treated with five levels of nitrogen: 0, 1, 10, 30, 60 mg L(-1) ammonia-N (NH(4)Cl) for 5d. After having explored the stress range of ammonia-N, its effect on E. densa was further examined at three levels of ammonium (0, 1, 30 mg L(-1) ammonia-N) and at six exposure times (0, 1, 2, 3, 5 and 7d). In testing the concentration-dependent stress, the increase of ammonia-N reduced the amounts of total chlorophyll (chl a and b), soluble proteins and soluble carbohydrates, but increased the activity levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase and peroxidase in E. densa. In the N-free medium, total chlorophyll, soluble proteins, soluble carbohydrates and the activities of SOD and peroxidase in E. densa decreased significantly compared with the control (1 mg L(-1) ammonia-N). When comparing the ammonia-N impacts over time, the plants showed a declining trend in total chlorophyll, soluble proteins and soluble carbohydrates, but an rising trend in MDA, SOD, peroxidase and catalase in 30 mg L(-1) ammonia-N over 7d. Compared with the control, the N-free medium significantly decreased the amounts of total chlorophyll, soluble proteins, soluble carbohydrates, SOD and peroxidase in E. densa over time. Our study indicates that high ammonium (ammonia-N ≥ 10 mg L(-1)) affects the growth of E. densa through inducing oxidative stress and inhibiting photosynthesis, and nitrogen deficiency can also induce an abiotic stress condition for the E. densa growth by reducing photosynthetic pigments, soluble proteins, soluble carbohydrates, and the activity of antioxidant enzymes.