Effects of photoperiod on growth, lipid metabolism and oxidative stress of juvenile gibel carp (Carassius auratus).

A 58-day cultivation experiment was carried out to investigate the effects of photoperiods on growth, lipid metabolism and oxidative stress of juvenile gibel carp. Juveniles (5.41 ±â€¯0.01 g) were cultured under seven light photoperiods (0 h of light (L):24 h of darkness (D), 4L:20D (12:00-16:00 light), 8L:16D (10:00-18:00 light), 12L:12D (8:00-20:00 light), 16L:8D (6:00-22:00 light), 20L:4D (4:00-24:00 light) and 24L:0D) in an indoor recirculating aquaculture system. The light intensity was 1.02 µmol·m-2·s-1 (at the tank bottom in a 0.5-m water depth). The fish were fed to satiety three times daily (8:30, 14:30 and 18:30). At the end of the experiment, final body weight, specific growth rate, feed efficiency and feed intake were significantly higher in 16L:8D, 20L:4D and 24L:0D groups than those in other groups (P < 0.05). Long-day photoperiods (16L:8D, 20L:4D and 24L:0D) simultaneously promoted lipogenesis, lipolysis and fatty acid oxidation. The increases in lipid retention efficiency, whole body lipid concentration and liver lipid content (P < 0.05) indicated that lipogenesis exceeded fatty acid oxidation. Liver oxidative stress was induced in juvenile gibel carp by short day lengths. The hepatic total antioxidant capacity, superoxide dismutase, glutathione peroxidase and the contents of metabolite glutathione were the highest in the short-day-length groups (0L:24D, 4L:20D and 8L:16D) (P < 0.05). Based on the growth performance and health status in the long-term cultivation experiment, the optimal photoperiods were 16L:8D, 20L:4D and 24L:0D in juvenile gibel carp.

[A preliminary study on origin of ligustrazine in Chuanxiong Rhizoma based on endogenetic Bacillus subtilis].

Ligustrazine is an important active ingredient of the traditional Chinese medicine Chuanxiong Rhizoma, but its content is a controversial topic. The endophytes of medicinal plants have the ability to produce the same active substances as the host, so this report focused on the endophytic Bacillus subtilis, to study the origin of ligustrazine in Chuanxiong Rhizoma preliminarily by inoculating the isolated endophytic B. subtilis to the Chuanxiong Rhizoma medium in vitro for solid state fermentation. Tissue grinding method was used to isolate the endogenetic B. subtilis. The morphological features, conventional physiological and biochemical reactions and 16S rRNA molecular techniques were combined to identify the endogenetic strains. Then, the strains that grew well in the medicinal matrix of Chuanxiong Rhizoma were screened out for further fermentation studies. The solid-state fermentation was performed at 37 °C for 30 d using Chuanxiong Rhizoma fermentation medium (40 g Chuanxiong Rhizoma powder, 100 mL sterile water, 121 °C, sterilization for 25 minutes). UPLC was used to detect the contents of ligustrazine, acetoin in the Chuanxiong Rhizoma fermentation medium and Chuanxiong Rhizoma. All the five strains were Gram-positive and had spores. Phylogenetic analysis of the 16S rRNA sequence showed that the endophytes were B. subtilis. The results of UPLC showed that ligustrazine was detected in the Chuanxiong Rhizoma fermentation medium inoculated with endogenetic B. subtilis LB3, LB3-2-1, LB4, LB5 and LB6-2, while not detected neither in blank Chuanxiong Rhizoma fermentation medium nor in Chuanxiong Rhizoma. This study showed that the endogenetic B. subtilis of Ligusticum chuanxiong Hort. can make use of Chuanxiong Rhizoma fermentation medium to produce ligustrazine. Endogenetic B. subtilis has a certain correlation with the accumulation of ligustrazine in Rhizoma Chuanxiong. We speculate that the ligustrazine may be derived from the catabolism of endogenetic B. subtilis in Ligusticum chuanxiong.

Different physiological roles of insulin receptors in mediating nutrient metabolism in zebrafish.

Insulin, the most potent anabolic hormone, is critical for somatic growth and metabolism in vertebrates. Type 2 diabetes, which is the primary cause of hyperglycemia, results from an inability of insulin to signal glycolysis and gluconeogenesis. Our previous study showed that double knockout of insulin receptor a ( insra) and b ( insrb) caused ß-cell hyperplasia and lethality from 5 to 16 days postfertilization (dpf) (Yang BY, Zhai G, Gong YL, Su JZ, Han D, Yin Z, Xie SQ. Sci Bull (Beijing) 62: 486-492, 2017). In this study, we characterized the physiological roles of Insra and Insrb, in somatic growth and fueling metabolism, respectively. A high-carbohydrate diet was provided for insulin receptor knockout zebrafish from 60 to 120 dpf to investigate phenotype inducement and amplification. We observed hyperglycemia in both insra-/- fish and insrb-/- fish. Impaired growth hormone signaling, increased visceral adiposity, and fatty liver were detected in insrb-/- fish, which are phenotypes similar to the lipodystrophy observed in mammals. More importantly, significantly diminished protein levels of P-PPARα, P-STAT5, and IGF-1 were also observed in insrb-/- fish. In insra-/- fish, we observed increased protein content and decreased lipid content of the whole body. Taken together, although Insra and Insrb show overlapping roles in mediating glucose metabolism through the insulin-signaling pathway, Insrb is more prone to promoting lipid catabolism and protein synthesis through activation of the growth hormone-signaling pathway, whereas Insra primarily acts to promote lipid synthesis via glucose utilization.