Transcriptional response to cold and fasting acclimation in Onychostoma macrolepis during the overwintering stage

Seasonal modulation of the testis transcriptome reveals insights into hibernation and reproductive adaptation in Onychostoma macrolepis

The Onychostoma macrolepis have a unique survival strategy, overwintering in caves and returning to the river for reproduction in summer. The current knowledge on the developmental status of its testes during winter and summer is still undiscovered. We performed RNA-seq analysis on O. macrolepis testes between January and June, using the published genome (NCBI, ASM1243209v1). Through KEGG and GO enrichment analysis, we were able to identify 2111 differentially expressed genes (DEGs) and demonstrate their functions in signaling networks associated with the development of organism. At the genomic level, we found that during the overwintering phase, genes associated with cell proliferation (ccnb1, spag5, hdac7) were downregulated while genes linked to testicular fat metabolism (slc27a2, scd, pltp) were upregulated. This indicates suppression of both mitosis and meiosis, thereby inhibiting energy expenditure through genetic regulation of testicular degeneration. Furthermore, in January, we observed the regulation of autophagy and apoptosis (becn1, casp13), which may have the function of protecting reproductive organs and ensuring their maturity for the breeding season. The results provide a basis for the development of specialized feed formulations to regulate the expression of specific genes, or editing of genes during the fish egg stage, to ensure that the testes of O. macrolepis can mature more efficiently after overwintering, thereby enhancing reproductive performance.

A comparative study of dietary amino acid patterns: unveiling growth, composition, and molecular signatures in juvenile Onychostoma macrolepis

The wild Onychostoma macrolepis, a species under national class II protection in China, lacks a specific compound feed for captive rearing. Understanding the dietary amino acid pattern is crucial for optimal feed formulation. This study aimed to investigate the effects of the four different dietary amino acid patterns, i.e., anchovy fishmeal protein (FMP, control group) and muscle protein (MP), whole-body protein (WBP), fish egg protein (FEP) of juvenile Onychostoma macrolepis, on the growth performance, body composition, intestinal morphology, enzyme activities, and the expression levels of gh, igf, mtor genes in juveniles. In a 12-week feeding trial with 240 juveniles (3.46±0.04g), the MP group demonstrated superior outcomes in growth performance (FBW, WGR, SGR), feed utilization efficiency (PER, PRE, FCR). Notably, it exhibited higher crude protein content in whole-body fish, enhanced amino acid composition in the liver, and favorable fatty acid health indices (AI, TI, h/H) in muscle compared to other groups (P < 0.05). Morphologically, the MP and FMP groups exhibited healthy features. Additionally, the MP group displayed significantly higher activities of TPS, ALP, and SOD, along with elevated expression levels of gh, igf, mtor genes, distinguishing it from the other groups (P < 0.05). This study illustrated that the amino acid pattern of MP emerged as a suitable dietary amino acid pattern for juvenile Onychostoma macrolepis. Furthermore, the findings provide valuable insights for formulating effective feeds in conserving and sustainably farming protected species, enhancing the research's broader ecological and aquacultural significance.

Multi-Omics Reveals the Effects of Spirulina platensis Powder Replacement of Fish Meal on Intestinal Metabolism and Stress in Zig-Zag Eel (Mastacembelus armatus)

The booming aquaculture industry has created a strong demand for fishmeal and increased environmental pressures. Spirulina, as a potential alternative to fishmeal, has been shown to have growth-promoting and animal health-enhancing properties. In this study, 600 large spiny loaches, divided into five experimental groups, F0, F1, F2, F3, and F4, were reared for 10 weeks using Spirulina platensis powder (SPP) as a substitute for 0%, 5%, 10%, 15%, and 20% of fishmeal, respectively. The results of intestinal physiological indexes showed that superoxide dismutase was lower than F0 in all treatment groups, and the activity of F3 was significantly lower than F0 (p < 0.05). The activity of malondialdehyde was significantly higher than that of F0 in all groups except F3 (p < 0.05). The addition of SPP also led to a decrease in the activity of acid phosphatase in the intestine, which was significantly lower in all treatment groups compared to the F0 group (p < 0.05). The results of serum physiology showed that the activity of superoxide dismutase in serum gradually increased with the increase in the percentage of SPP addition, and the F3 group produced a significant difference from the F0 group (p < 0.05). The transcriptomics results showed that DEGs in the low percentage substitution group (<15%) were mostly enriched in metabolism-related pathways, such as bile secretion; DEGs in the high percentage substitution group (>15%) were mostly enriched in inflammation-related pathways, such as complement p and coagulation cascades. Metabolomics confirmed that nicotinate and nicotinamide metabolism and glycerophospholipid metabolism were the two pathways that were significantly enriched in the treatment groups of fishmeal replacement by SPP. The present study demonstrated that a low percentage (<15%) of fishmeal replacement by SPP in feed mobilized MA digestive metabolism, whereas a high percentage (>15%) of replacement induced intestinal stress. Considering the health and farm efficiency aspects, the proportion of SPP in feed formulation for MA should be less than 15%.

The Role of lncRNAs in Pig Muscle in Response to Cold Exposure

Cold exposure is an essential factor affecting breeding efforts in cold regions. Muscle, as an important tissue for homeothermic animals, can produce heat through shivering thermogenesis (ST) and non-shivering thermogenesis (NST) under cold exposure. Long non-coding RNAs (lncRNAs) play important roles in regulating gene expression. However, the regulatory mechanisms of lncRNAs and their role in the thermogenesis of pigs are unclear. We examined lncRNAs in the skeletal muscle of an indigenous pig breed, the Enshi black pig, when the pigs were exposed to acute or chronic cold. Three pigs were maintained inside a pig house (control group), three pigs were maintained outside the pig house for 55 d (chronic cold group), and three pigs were suddenly exposed to the conditions outside the pig house for 3 days (acute cold group). After the experiment, the longissimus dorsi of each pig were collected, and their lncRNA profiles were sequenced and analyzed. Each sample obtained nearly 12.56 Gb of clean data. A total of 11,605 non-coding RNAs were obtained, including 10,802 novel lncRNAs. The number of differentially expressed lncRNAs (DElncRNAs) was identified under acute cold (427) and cold acclimation (376), with 215 and 192 upregulated lncRNAs, respectively. However, only 113 lncRNAs were commonly upregulated by acute cold and cold acclimation. In addition, 65% of the target genes were trans-regulated by DElncRNAs. The target genes were enriched in signal transduction, immune system, cell growth and death pathways, and amino acid and carbohydrate metabolism. Compared to cold acclimation, acute cold stress-induced more DElncRNAs and response pathways. In conclusion, low temperatures altered the expression levels of lncRNAs and their target genes in muscle tissue. Some potential mechanisms were revealed, including ion migration and the metabolism of amino acids and carbohydrates.