Discontinuous Administration of β-glucan is Effective for Preventing Immune Fatigue in Litopenaeus vannamei

β-glucan is an effective, available immunostimulant that has been successfully used to improve the immune defense of shrimp against pathogenic infection. However, the long-term continuous use of β-glucan can lead to immune fatigue, and intermittent feeding may be an effective way of avoiding this phenomenon. A 60-day growth trial was conducted to compare the effects of different feeding strategies of diets containing 200 mg/kg β-glucan on the growth and immune system of the Pacific white shrimp Litopenaeus vannamei. The results showed that either continuous feeding or intermittent feeding of diets containing 200 mg/kg β-glucan did not promote the growth of L. vannamei. However, the levels of superoxide dismutase, alkaline phosphatase, and acid phosphatase in the hepatopancreas of L. vannamei in the intermittent feeding group were significantly higher than those in the control and continuous feeding groups. Expression levels of the genes encoding LPS/β-glucan binding protein, superoxide dismutase, lysozyme, penaeid in-3a, and catalase were also significantly upregulated in the intermittent feeding group, whereas most of the immune parameters in the continuous feeding group were not significantly different from those of the control group. After artificial infection with Vibrio parahaemolyticus, the average mortality rates in the control group, the continuous feeding group, and the intermittent feeding group were 76.67%, 78.89%, and 45.56%, respectively. The results indicated that the addition of 200 mg/kg β-glucan to the diet did not promote the growth of L. vannamei, but the strategy of intermittent feeding effectively prevented immune fatigue and enhanced disease resistance, perhaps by increasing nonspecific immunity in L. vannamei

Graphic Novels: Let's Hear From You!

Former URI: http://hdl.handle.net/10125/59386Public libraries are an important part of our society and provide a sanctuary for all seeking knowledge and comfort. Graphic novels have become a rising trend within public libraries, however at times it can be difficult to place them. Check out this session about graphic novels by two librarians who are just crazy about them! Bring your questions, get opinions from Hillary and Kelly regarding the latest trends and how it can help your graphic novel collections succeed. We are gonna hear from you on your thoughts and questions and hopefully you leave satisfied and knowing how to work with this insanely popular literary medium

Inhibitory Effects of Galla chinensis, Tannic Acid, and Gallic Acid on Saprolegnia parasitica

The inhibitory effects of Galla chinensis and its two main ingredients, tannic acid and gallic acid, on Saprolegnia parasitica were examined, using the method of agar plate assay and liquid dilution assay. The results showed that all the three tested drugs had different degrees of inhibitory activity on mycelial growth and zoospore germination of Saprolegnia parasitica, with tannic acid showing the most significant inhibition. The mycelial growth of S. parasitica was completely inhibited by tannic acid at the concentration of more than 32 mg/L, and the germination rate of S. parasitica zoospores decreased by 66% at a concentration of 5 mg/L. Considering the low cost of tannic acid together with its inhibitory effect on S. parasitica, tannic acid showed the most significant potential in the prevention and control of fish saprolegniasis

Nitrite-Induced Oxidative Stress, Histopathology, and Transcriptome Changes in the Mud Crab (Scylla paramamosain)

Nitrite in the aquatic environment is highly toxic to aquatic animals. However, the mechanism by which the mud crab responds to nitrite-induced stress remains unclear. In this study, we investigated the physiological response and molecular mechanism in the mud crab (Scylla paramamosain) exposed to the acute nitrite exposure (20 mg/L) for 24h. The results showed that nitrite exposure induced significant changes in antioxidant enzyme activity and MDA content. Severe cytological damage was observed in the hepatopancreas. After 24h exposure to nitrite, 11,638 differentially expressed genes (DEGs) were identified by transcriptome analysis. These DEGs were involved in many pathways related to oxidative stress and immune responses. Our results also found that FoxO signaling pathway, p53 signaling pathway, and NF-kB signaling pathway participated in the anti-stress defense against nitrite stress. The study provides new insight into the understanding of nitrite-induced toxicity in the mud crab

Molecular Cloning, mRNA Expression, and Nutritional Regulation of a Fatty Acyl Δ6-Desaturase-like Gene of the Manchurian Trout, Brachymystax lenok (Pallas)

The fatty acyl delta-6 desaturase (Δ6-desaturase) is a key rate-limiting enzyme in the biosynthesis of long-chain polyunsaturated fatty acids (LCPUFAs). To study the effects of different oil sources in the feed on the nutritional regulation of Δ6-desaturase-like gene mRNA expression, the fulllength cDNA of the Δ6-desaturase-like gene was cloned from the liver of Manchurian trout (Brachymystax lenok). A 9-week feeding trial was performed, and the fish received diets with three different oil sources: fish oil (FO), sunflower oil (SO), and linseed oil (LO). The results showed that the 2448 bp long full-length cDNA contained an open reading frame (with a length of 1365 bp), encoding 454 amino acids. Gene expression analysis indicated that Δ6-desaturase-like gene mRNA is widely distributed throughout different tissues, with highest expression levels in both the liver and the brain. The linolenic acid (ALA) and linoleic acid (LA) compositions were highest in LO and SO diets, respectively. The eicosapentaenoic acid and docosahexaenoioc acid composition in LO and SO diets were significantly lower than in the FO diet. Fish fed with SO and LO showed significantly higher liver expression levels of Δ6-desaturase-like gene mRNA than those fed with FO. This indicates that SO and LO in the diet affected the nutritional regulation of the Δ6-desaturase-like gene mRNA in the liver of the Manchurian trout. In addition, these data suggest that the Manchurian trout has the ability to synthesize long-chain unsaturated fatty acids (LC-PUFAs) from ALA and LA

Withdrawal Period of Oxolinic Acid in Cobia (Rachycentron canadum): Validation of an LC-MS/MS Method

Oxolinic acid (OXO) has been routinely used in aquaculture as both prophylactic and chemotherapeutic agents, principally against systemic bacterial infections. The residue depletion of OXO was investigated in cobia following multiple (5 days) in-feed dosing (30 and 60 mg/kg body weight/day) at 25°C; we assessed OXO concentrations of liver and muscle (+skin) samples post-treatment for three weeks. The OXO residues were quantified using a validated ultra-high-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS) method and the results indicated recoveries of 86.6-95.8%, with relative standard deviations (RSD) less than 8.5% for intra- and inter-day precisions. Within the range of 10−500 ng/g, the calibration curves for all matrices presented a determination coefficient greater than 0.99. Limit of detection and quantification were estimated at 6 and 10 ng/g, respectively. In order to account for the high variability of the residue data, a safety span corresponding to 50% of depletion time could be seen as appropriate. Considering a maximum residue limit (MRL) of 50 ng/g established by the Taiwan FDA for OXO in muscle with skin in natural proportions, a withdrawal period of 15 days was calculated for the sum of 10day depletion time and 5-day safety span. These results revealed that the analytical method is developed for residue OXO and that the withdrawal period is appropriate

Effect of Dietary Iron Levels on Tissues, Intestinal Digestive Enzyme Activity, and Muscle Nutrient Compositions of Juvenile Bighead Carp (Aristichthys nobilis)

A 60-day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on iron concentration in tissues, intestinal digestive enzyme activities, and muscle nutrient composition of bighead carp (Aristichthys nobilis). Six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diets) using ferrous sulfate (FeSO4) as the source. When Fe dietary content increased to 43.1 mg/kg, trypsin activity in the intestine significantly increased and thereafter decreased. Lipase and amylase activity in the intestine significantly increased with increasing dietary Fe levels up to 123.3 mg/kg diet and thereafter decreased. With lipase and amylase activity in the intestine as the main indicators, Fe content of 123.3 mg/kg was the most suitable dietary Fe level for A. nobilis. Crude protein content in the muscle of the 84.2 mg/kg Fe group was the highest in all groups. Results indicated that the appropriate levels of dietary Fe alter muscle nutrient composition of A. nobilis. Fe content in the muscle and vertebrae significantly increased with increasing dietary Fe levels up to 203.1 mg/kg diet. Fe contents in different tissues were as follows: Vertebra >intestine >muscle