Heat Stress Weakens the Skin Barrier Function in Sturgeon by Decreasing Mucus Secretion and Disrupting the Mucosal Microbiota.

Heat stress induced by global warming has damaged the well-being of aquatic animals. The skin tissue plays a crucial role as a defense barrier to protect organism, however, little is known about the effect of heat stress on fish skin, particularly in cold-water fish species. Here, we investigated the effects of mild heat stress (24°C, MS) and high heat stress (28°C, HS) on Siberian sturgeon skin using RNA-seq, histological observation, and microbial diversity analysis. In RNA-seq, 8,819 differentially expressed genes (DEGs) in MS vs. C group and 12,814 DEGs in HS vs. C group were acquired, of which the MS vs. C and HS vs. C groups shared 3,903 DEGs, but only 1,652 DEGs were successfully annotated. The shared DEGs were significantly enriched in pathways associating with mucins synthesis. Histological observation showed that the heat stresses significantly reduced the number of skin mucous cells and induced the damages of epidermis. The microbial diversity analysis elicited that heat stress markedly disrupted the diversity and abundance of skin microbiota by increasing of potential pathogens (Vibrionimonas, Mesorhizobium, and Phyllobacterium) and decreasing of probiotics (Bradyrhizobium and Methylovirgula). In conclusion, this study reveals that heat stress causes adverse effects on sturgeon skin, reflecting in decreasing the mucus secretion and disordering the mucosal microbiota, which may contribute to develop the preventive strategy for heat stress caused by global warming.

Damage Identification Method for Medium- and Small-Span Bridges Based on Macro-Strain Data under Vehicle-Bridge Coupling.

The damage identification method based on macro-strain modality has shown good results for large-span flexible bridges. However, medium- and small-span bridges have a high stiffness, and the axle system is embodied. The strong time-varying vibration characteristics, coupled with the non-stationary characteristics of vehicle loads, make it difficult to accurately determine the stable strain modes of such bridges. To solve this problem, a damage localization index in the form of an amplitude vector matrix of the mutual energy density spectrum based on macro-strain was constructed using wavelet transform de-noising and reconstruction technology and cross-correlation function. The macro-static strain and macro-dynamic strain data obtained from a vehicle-bridge coupling experiment were reconstructed through wavelet transform, and the factors influencing the damage indices were analyzed. The results showed that the proposed indicators could help realize an accurate damage localization for medium- and small-span bridge systems with different damage degrees under the action of vehicle-bridge coupling.

Design of Flow Velocity and Direction Monitoring Sensor Based on Fiber Bragg Grating.

The real-time monitoring of the flow environment parameters, such as flow velocity and direction, helps to accurately analyze the effect of water scour and provide technical support for the maintenance of pier and abutment foundations in water. Based on the principle of the Fiber Brag Grating sensor, a sensor for monitoring the flow velocity and direction in real-time is designed in this paper. Meanwhile, the theoretical calculation formulas of flow velocity and direction are derived. The structural performance of the sensor is simulated and analyzed by finite element analysis. The performance requirements of different parts of the sensor are clarified. After a sample of the sensor is manufactured, calibration experiments are conducted to verify the function and test the accuracy of the sensor, and the experimental error is analyzed. The experimental results indicate that the sensor designed in this paper achieves a high accuracy for the flow with a flow velocity of 0.05-5 m/s and the flow velocity monitoring error is kept within 7%, while the flow direction monitoring error is kept within 2°. The sensor can meet the actual monitoring requirements of the structures in water and provide reliable data sources for water scour analysis.

Differential transcriptomic analysis of crayfish (Procambarus clarkii) from a rice coculture system challenged by Vibrio parahaemolyticus.

Rice-crayfish (Procambarus clarkii) coculture is an effective farming mode and has been promoted in various regions of China. However, infection in crayfish can be a significant economic drain. We found crayfish infected with Vibrio parahemolyticus (VP), and to understand the molecular mechanisms of the immune responses of crayfish to VP infection, Illumina sequencing was employed to identify changes in the mRNA of hepatopancreatic tissue. A total of 47.30 and 43.01million high-quality transcriptome reads were generated from the hepatopancreatic samples of the experimental group (EG) and control group (CG), respectively. We found 5559 genes were significantly differentially expressed, including 2521 up-regulated genes (45.35%) and 3038 down-regulated genes (54.65%). These genes were enriched in 126 GO terms and 76 KEGG pathways (P ≤ 0.05), including the MAPK and PI3K-Akt signaling pathways and cell adhesion molecules, with 23 up-regulated genes and 3 down-regulated genes related to immune responses in the EG relative to the CG. Histopathological analysis revealed that the epithelial cells of the hepatopancreatic tubules in the EG were severely atrophic, necrotic, and exfoliated, resulting in thin and collapsing hepatopancreatic tubules. The expression patterns of 8 differentially expressed genes involved in immune responses were validated by quantitative real-time RT-PCR. These results provide a valuable basis for the immune responses of crayfish to acute hepatopancreatic necrosis disease at transcriptome level.

The complete mitochondrial genome of Garra imberba (Teleostei, Cyprinidae, Garra).

The beardless sucking bard, Garra imberba, is an important economic freshwater fish with very limited yield. In this study, we successfully sequenced the first mitochondrial genome of G. imberba by PCR. The mitogenome is 16,600 bp in length, containing 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region (D-loop). The overall base composition of the H-strand is 31.5% A, 26.7% T, 16.1% C, and 25.8% G, with a slight AT bias of 58.2%. Most of the genes are encoded on heavy strand, except for eight tRNAs (tRNA(Gln), tRNA(Ala), tRNA(Asn), tRNA(Cys), tRNA(Tyr), tRNA(Ser), tRNA(Glu) and tRNA(Pro)) and ND6 genes.

The complete mitochondrial genome of Schizopygopsis chengi baoxingensis (Teleostei, Cyprinidae, Schizopygopsis).

Schizopygopsis chengi baoxingensis is endemic to the Baoxing River in China and may become an endangered species due to its very narrow habitat and the construction of hydropower dams. In this study, we successfully sequenced the first mitochondrial genome of S. c. baoxingensis. The mitogenome is 16,787 bp in length, containing 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region (D-loop). The overall base composition of the H-strand is 28.5% A, 26.2% T, 18.4% C, and 26.9% G, with a slight AT bias of 54.7%. The sequenced mtDNA genome of S. c. baoxingensis is similar in gene arrangement to that of other cyprinidaes except for a 191 bp non-coding region found between tRNA(Thr) and tRNA(Pro).

The complete mitochondrial genome of Schizothorax prenanti (Tchang) (Teleostei, Cyprinidae, Schizothoracinae).

The ya-fish, Schizothorax prenanti, is a well-known commercial cold-water fish species with the hexaploid karyotype distributed in the upper reaches of the Yangtze River and its tributaries on the western Sichuan Plateau in China. The complete mitogenome of S. prenanti is 16,587 bp in length, containing 37 genes of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a control region (D-loop). The gene nucleotide composition of S. prenanti is 29.6% A, 25.4% T, 27.1% C and 17.9% G, with a slight AT bias of 55.0%. The complete mitogenome sequence of S. prenanti could provide useful data for further studies on genetic structure and diversity, as well as the artificial cultivation and breeding of S. prenanti.

Estimation of nutrient sources and transport using Spatially Referenced Regressions on Watershed Attributes: a case study in Songhuajiang River Basin, China.

We report here the first application of the Spatially Referenced Regressions on Watershed Attributes (SPARROW) model to China, a country naturally and culturally distinct from previous SPARROW applications. The Songhuajiang River Basin (556,700 km(2)) empties into the Tongjiang monitoring section, a shared water resource of great import for both Chinese and Russian citizens. The model was calibrated to annual loads of total nitrogen (TN) at 102 sites and total phosphorus (TP) at 65 sites. We assessed the rates of delivery and loss of nutrients from diffuse sources and also provided reach-level predictions of the percentage of nutrient loads delivered from upstream subbasins to Tongjiang monitoring section. The results indicated that farmland and pasture land were responsible for about 70 % of nutrient inputs to the Tongjiang monitoring section. Point source inputs were not statistically significant sources of TN or TP. We presented evidence that rice paddies delivered less TN to streams per area than other types of cropland. The locations responsible for the highest TN and TP inputs to the Tongjiang monitoring section tended to be located near the mainstream, though the areas of highest TN delivered yield did not correspond to the areas of highest TP delivered yield. This suggests that different management priorities may be needed in different parts of the Songhuajiang River Basin.

The complete mitochondrial genome of Liobagrus marginatus (Teleostei, Siluriformes: Amblycipitidae).

The Liobagrus marginatus is an economic fish which distribute in the upstream of Yangtze river and its distributary. For its taste fresh, environmental pollution and overfishing, its population declined drastically and body miniaturization in recent decades, so it is essential to protect its resource. In this study, the complete mitochondrial genome sequence of Liobagrus marginatus was sequenced, which contains 22 tRNA genes, 13 protein-coding genes, 2 rRNA genes, and a non-coding control region with the total length of 16,497 bp. The gene arrangement and composition are similar to most of other fish. Most of the genes are encoded on heavy-strand, except for eight tRNA and ND6 genes. Just like most other vertebrates, the bias of G and C has been found in statistics results of different genes/regions. The complete mitochondrial genome sequence of Liobagrus marginatus would contribute to better understand population genetics, evolution of this lineage, and will help administrative departments to make rules and laws to protect it.

The complete mitochondrial genome of the Elongate loach Leptobotia elongata (Cypriniformes: Cobitidae).

The Elongate loach (Leptobotia elongata) belongs to family Cobitidae, which is endemic to the middle and upper reaches of the Yangtze River in China. In this study, the complete mitochondrial genome of L. elongata was sequenced. It was determined to be 16,591 bases. The nucleotide sequence data of 12 heavy-strand protein-coding genes of L. elongata and other 12 Cobitidae species were used for phylogenetic analyses. Trees constructed using Bayesian and maximum parsimony showed a similar topology demonstrating that L. elongate was clustered in subfamily Botiinae being sister to the subfamily Cobitinae. The trees also suggested that the genera Cobitis were polyphyletic.