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Single-Cell Suspension Preparation from Nile Tilapia Intestine for Single-Cell Sequencing

Nile tilapia is one of the most commonly cultured freshwater fish species worldwide and is a widely used research model for aquaculture fish studies. The ...

Hainan University

This study investigates the occurrence and distribution of microplastics in water, sediment, and crayfish samples within pond and rice-crayfish co-culture breeding modes in Jianli prefecture, China. Microplastics in environmental and biological samples were systematically extracted by CaCl solution, digested by HO and KOH, and identified by μ-FTIR. A cleansing treatment for crayfish was performed in pure water before dissection and microplastic accumulation in different tissues (gill, stomach, gut, and flesh) of non-cleansed and cleansed crayfish were compared. The average microplastic abundances were 1.3 ± 0.1-2.5 ± 0.1 particles/L, 0.03 ± 0.01-0.04 ± 0.02 particles/g, and 0.17 ± 0.07-0.92 ± 0.19 particles/individual in water, sediment, and crayfish samples, respectively. Microplastics were detected in all studied crayfish tissues, except the flesh. There were no significant differences in microplastic abundances in water (P = 0.82), sediment (P = 0.90), and crayfish (P = 0.47 for non-cleansed samples; P = 0.30 for cleansed samples) between two breeding modes despite the detection of relatively higher microplastic abundances in the samples from the pond breeding mode. Microplastic accumulation in non-cleansed crayfish stomachs and guts (0.71 ± 0.18 particles/individual) was higher (P < 0.01) than that recorded in their gills (0.13 ± 0.06 particles/individual). Moreover, microplastics present in the stomachs and guts of cleansed crayfish were significantly less abundant (P < 0.01) than in non-cleansed crayfish, although this was not observed in the gills (P = 0.99). The majority of microplastic particles in this study had fiber-like shapes, blue and transparent colors, a size smaller than 1 mm, and polymer types of PP:PE and PE. The results demonstrate that microplastics in the environment can accumulate in the internal tissues of crayfish, which may pose a potential risk to humans through food consumption without the removal of the gills, stomach, and guts. This study provides valuable information for understanding microplastic accumulation in the different tissues of crayfish and the potential risk of human exposure to microplastics from crayfish as a food supplement.

Microplastic pollution in water, sediment, and specific tissues of crayfish (Procambarus clarkii) within two different breeding modes in Jianli, Hubei province, China.

A potential host-derived probiotic, Bacillus subtilis 6-3-1, was successfully screened from 768 isolates from the intestines of healthy hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) based on multiple probiotic characteristics in vitro assays, such as, non-hemolytic activity, extracellular enzyme activity, inhibitory activity against pathogens, tolerance to gastrointestinal stress, cell surface hydrophobicity, autoaggregation, and antibiotic susceptibility. Eight weeks of feeding trial revealed that dietary supplementation of B. subtilis 6-3-1 at all three concentrations (1 × 10 CFU g as BS6; 1 × 10 CFU g as BS7; 1 × 10 CFU g as BS8) could promote the growth performance of hybrid groupers to a certain extent at different time points. At the end of 8th week, BS6 and BS8 significantly promoted the weight gain rate (WGR), specific growth rate (SGR) of hybrid groupers. The digestive enzyme activities were also increased in BS6 and BS8 groups comparing with those in control group, except that the increase of amylase activities in BS6 was not significant (P > 0.05). However, BS7 showed the best non-specific immunity stimulating effects among the three concentration groups. While BS7 significantly boosted serum total protein contents, lysozyme (LZM), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and acid phosphatase (ACP) levels, BS6 significantly enhanced serum total protein, LZM activity, and BS8 significantly improved LZM, respiratory bursts activity. B. subtilis 6-3-1 up-regulated the expression of MyD88 in head kidney and intestine and increased villi length (VL) in intestine of BS7 group. It also up-regulated the expression of IgM in head kidney in BS6 group and IgM and TLR1 in intestine of BS8 group. Though all B. subtilis 6-3-1 supplemented groups reduced the cumulative mortality rate post-Vibro harveyi-challenge, BS7 showed the best protection effects among the three concentration groups. In conclusion, with its immune promoting, intestine health enhancing, and V. harveyi resisting effects, BS7 show great potential to be used as a probiotic in hybrid grouper culture.

Effects of a Potential Host Gut-Derived Probiotic, Bacillus subtilis 6-3-1, on the Growth, Non-specific Immune Response and Disease Resistance of Hybrid Grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂).

The dinoflagellate Amyloodinium ocellatum is an important pathogenic parasite infecting cultured marine and brackish water fishes worldwide. This includes cultured Florida pompano (Trachinotus carolinus), which is one of the most desirable marine food fish with high economic value in the USA. A. ocellatum infects fish gills and causes tissue damage, increased respiratory rate, reduced appetite, and mortality, especially in closed aquaculture systems. This study mimicked the natural infection of A. ocellatum in cultured pompano and conducted a transcriptomic comparison of gene expression in the gills of control and A. ocellatum infected fish to explore the molecular mechanisms of infection. RNA-seq data revealed 604 differentially expressed genes in the infected fish gills. The immunoglobulin genes (including IgM/T) augmentation and IL1 inflammation suppression were detected after infection. Genes involved in reactive oxygen species mediating parasite killing were also highly induced. However, excessive oxidants have been linked to oxidative tissue damage and apoptosis. Correspondingly, widespread down-regulation of collagen genes and growth factor deprivation indicated impaired tissue repair, and meanwhile the key executor of apoptosis, caspase-3 was highly expressed (25.02-fold) in infected fish. The infection also influenced the respiratory gas sensing and transport genes and established hypoxic conditions in the gill tissue. Additionally, food intake and lipid metabolism were also affected. Our work provides the transcriptome sequencing of Florida pompano and provides key insights into the acute pathogenesis of A. ocellatum. This information can be utilized for designing optimal disease surveillance strategies, future selection for host resistance, and development of novel therapeutic measures.

Dongdong Zhang

State Key Laboratory of Marine Resource Utilization in South China Sea,
Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology,
College of Marine Science

Hainan University

Single-Cell Suspension Preparation from Nile Tilapia Intestine for Single-Cell Sequencing

Dongdong Zhang

State Key Laboratory of Marine Resource Utilization in South China Sea,Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology,College of Marine Science

Hainan University

Single-Cell Suspension Preparation from Nile Tilapia Intestine for Single-Cell Sequencing

State Key Laboratory of Marine Resource Utilization in South China Sea,
Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology,
College of Marine Science