Acute cold stress induces intestinal injury via CIRP-TLR4-IRE1 signaling pathway in pre-starter broilers.

BACKGROUND: Cold stress is a common environmental stress in broiler chicks. Cold-inducible RNA-binding protein (CIRP) is a conserved cold shock protein that can regulate inflammatory response through Toll-like receptor 4 (TLR4). The mechanism that how CIRP involves in the regulation of cold stress in broilers remains unclear. METHODS AND RESULTS: In this study, 360 7-day-old healthy male SZ901 chicks were selected and randomly allocated to four groups, and then subjected to acute cold exposure at the ambient temperature of 12 ± 1 °C for 0 h, 4 h, 8 h, and 12 h, respectively. After cold exposure, abdominall skin temperature, gene expression of CIRP-TLR4-IRE1 signaling pathway in ileum mucosa, and small intestinal structure were measured. The results showed that cold exposure decreased abdominall skin temperature, upregulated the gene expression of endoplasmic reticulum stress (ERS) markers IRE1, inflammatory factors IL-1ß, IL-6, IL-10, TNF-α, and tight junction proteins ZO-1 and Occludin in ileum of chicks compared with the control group with no (0 h) cold exposure. Compared with the control group, a long time cold exposure upregulated the gene expression of CIRP, TLR4, GRP78, NF-κB in ileum mucosa, and decreased the villus height and V/C of small intestine. CONCLUSIONS: The above results suggest that acute cold stress induces endoplasmic reticulum stress via upregulating the gene expression of CIRP-TLR4-IRE1 signaling pathway, and results in the structural damage of chick intestine.

Tryptophan alleviates chronic heat stress-induced impairment of antioxidant capacities, inflammatory response, and mitochondrial function in broilers.

The aim of this study was to investigate the effect of dietary tryptophan (Trp) supplementation on serum biochemical indices, antioxidant indices, cytokine levels, mitochondrial biosynthesis, and mitochondrial morphology of heat-stressed broilers. A total of 180 female Arbor Acres broilers (18-day-old) were randomly allocated into three groups with six replicates of 10 broilers each. Broilers in thermoneutral (TN) (23 ± 1 °C) group were fed a basal diet; the other two groups were fed the basal diet supplemented with 0 or 0.18% Trp under heat stress (HS) (34 ± 1 °C for 8 h/day (h/day) and 23 ± 1°C for the remaining time) condition. The heat stress lasted for 21 days (days 21 to 42). The results indicated that heat stress reduced serum total protein content (TP) and decreased the activities of serum superoxide dismutase (SOD) and total antioxidant capacity (T-AOC), but increased the levels of serum uric acid (UA), interleukin (IL)-1ß, IL-6, and IL-18 (P < 0.05) compared to the TN group. However, dietary supplementation with 0.18% Trp enhanced serum TP content, glutathione peroxidase (GSH-Px), SOD, catalase (CAT) activities, and T-AOC; decreased aspartate aminotransferase (AST) activities (P < 0.05); and lowered serum IL-1ß, IL-6, IL-18 contents (P < 0.05). Meanwhile, heat stress exposure downregulated the mRNA expression of mitochondrial transcription factor A (TFAM), cytochrome c oxidase subunit 1 (COX1), and cytochrome c oxidase subunit 5A (COX5A) in ileum (P < 0.05) as compared to the TN group. Dietary Trp supplementation enhanced the mitochondrial membrane potential (MMP) and the mRNA expression of TFAM, COX1 in ileum mucosa (P < 0.05) and ameliorated the damage of mitochondrial structure. Collectively, dietary supplementation with Trp could improve antioxidant capacity and mitochondrial structure and regulate mitochondrial function-related genes and decrease inflammatory response in heat-stressed broilers. Dietary Trp supplementation might be an effective nutritional strategy to protect against heat stress impairment.

Construction of a thermo-sensitive pRI857 vector for efficient DNA capturing in Escherichia coli.

OBJECTIVES: To establish a positive cloning system with a zero background for high-throughput DNA cloning purpose. RESULTS: The cloning vector, pRI857, and the genomic-library construction vector, pRI857-BAC, were constructed based on the mechanism of expression of the thermo-sensitive cI857 repressor gene that can stringently repress the PR promoter and kanamycin resistance gene (PR-kan R ) at 30 °C, but have no effect on PR-kan R gene at 37 °C or at higher temperatures. When the pRI857 vectors were transformed into E. coli with or without a target foreign DNA fragment inserted at the BfrBI site of the cI857 gene, only colonies with the foreign DNA fragment survive. We extended this method to construct a pRI857-BAC vector for genomic library cloning which displays an efficiency of ~107 cfu per µg of genomic DNA, with no empty vectors detected. CONCLUSIONS: Cloning by indirect activation of resistance marker gene represents a novel DNA-capturing system, which can be widely applied for high-throughput DNA cloning.