Effect of salinity change on free amino acid content in Pacific oyster

ABSTRACT:   In order to identify free amino acids (FAA) that are importantas intracellular osmolytes in Crassostrea gigas , we investigatedthe change in FAA content in the mantle exposed to an abrupt decreaseor increase in salinity. In hypo-osmotic adaptation, most FAA showedremarkable and synchronous decreases from 2 to 8 h, suggestingthat the non-selective efflux of FAA was mainly responsible forthe decrease in FAA. Taurine that accounted for approximately 80% oftotal FAA content contributed most significantly to the hypo-osmoticadaptation. In hyper-osmotic adaptation, significant increases inglycine, alanine, β-alanine, proline, arginine and taurinewere observed. Of these, alanine showed an immediate increase thatis important to short-term adaptation to hyper-osmolality, whiletaurine showed a slower and substantial increase that contributesto a long-term adaptation to hyper-osmolality.     

Establishment of a mouse- and egg-adapted strain for the evaluation of vaccine potency against H3N2 variant influenza virus in mice

Sporadic spreads of swine-origin influenza H3N2 variant (H3N2v) viruses were reported in humans, resulting in 437 human infections between 2011 and 2021 in the USA. Thus, an effective vaccine is needed to better control a potential pandemic for these antigenically distinct viruses from seasonal influenza. In this study, a candidate vaccine strain with efficient growth capacity in chicken embryos was established through serial blind passaging of A/Indiana/08/2011 (H3N2)v in mice and chicken embryos. Seven amino acid substitutions (M21I in PA; A138T, N165K, and V226A in HA; S312L in NP; T167I in M1; G62A in NS1 proteins) were found in the passaged viruses without a major change in the antigenicity. This mouse- and egg-adapted virus was used as a vaccine and challenge strain in mice to evaluate the efficacy of the H3N2v vaccine in different doses. Antibodies with high neutralizing titers were induced in mice immunized with 100 µg of inactivated whole-virus particles, and those mice were significantly protected from the challenge of homologous strain. The findings indicated that the established strain in the study was useful for vaccine study in mouse models.     

桉树人工林木材皱缩型特性研究-Ⅰ.基本密度和一些构造指标与收缩和皱缩性质的相关性

皱缩型收缩是低中等密度桉树人工林木材被用于实木产品加工时最难以克服的缺陷之一.为此,本研究对种植在广西国营东门林场的3种易皱缩桉树(尾叶桉,巨桉,尾巨桉)木材的基本密度,微纤丝角(MFA),纤维双倍壁厚(DWT), 射线薄壁组织率(RP), 单位胞壁收缩率,总收缩率和残余皱缩几个与皱缩相关的材性指标进行了研究.结果表明:1)单位胞壁收缩率与基本密度具有极强的线性正相关性,与纤维双倍壁厚表现出中等至强的线性正相关性,而与射线薄壁组织率和微纤丝角呈现弱至中等的线性负相关性.基本密度能作为单独因子很好的预测单位胞壁收缩率(R2≥0.9412); 2)总收缩率与基本密度、纤维双倍壁厚、射线薄壁组织率具有弱至中等的线性正相关性,与微纤丝角呈现线性弱的负相关性.基本密度和上述3个解剖指标均不能单独作为预测总收缩率的因子(R2≤0.5712); 3)残余皱缩与基本密度和纤维双倍壁厚表现弱的线性负相关性,与微纤丝角呈现弱的线性正相关性,与射线薄壁组织率则表现了强的线性正相关性.因此,射线薄壁组织率是较好的残余皱缩的预测因子(R2≥0.7454).     

Expression of mRNA for sodium-glucose transporter 1 and fatty acid translocase in the ruminant gastrointestinal tract before and after weaning

The mRNA expression of sodium‐glucose transporter 1 (SGLT1) and fatty acid translocase (CD36) in the gastrointestinal tract of Holstein cattle and Saanen goats before and after weaning was investigated. Before weaning, the expression of both SGLT1 and CD36 was highest in the jejunum, relative to the other parts of the gastrointestinal tract in both species. The expression of SGLT1 and CD36 in the duodenum was second highest in the goats. After weaning, SGLT1 and CD36 expression in the small intestine significantly decreased in both species. The expression of both types of transporters was also detected in the forestomach. From these results, it was concluded that the jejunum is probably the major absorption site for glucose and long‐chain fatty acids before weaning, and that the expression of both types of transporters decreases after weaning in cattle and goats.     

Effect of dietary enzymes on the ileal digestibility and abdominal fat content in broilers

The effects of purified cellulase and a commercial feed enzyme (FE) containing cellulase, hemicellulase, pectinase and so on, on the performance, abdominal fat content, digestibility of ileal contents and metabolizable energy of broilers were examined. Male broiler chicks (Cobb strain) were divided into three groups: control, cellulase (1 U/g feed) and FE (0.6 mg/g feed) with seven replicates. Chicks were raised under a temperature condition of 25°C in wire bottom cages for 12 days from 15 days of age. Feed (corn–soybean meal diet: crude protein, 21%; metabolizable energy, 3000 kcal/kg) and water were offered ad libitum. Dietary cellulase had a negative effect on the bodyweight gain and feed conversion ratio. The FE had no effect on bodyweight gain, but tended to improve the feed conversion ratio. The ileal crude protein and ash digestibilities were improved by the FE, but not by the cellulase. Furthermore, cellulase decreased the abdominal fat content and the FE increased metabolizable energy. In conclusion, digestion is enhanced and an improvement in performance is brought about by FE and, interestingly, fat metabolism is affected by cellulase by an unknown mechanism.     

Influence of transport stress on serum cortisol and thyroid hormones in pigs with Halothane gene

The influence of transport stress on rectal temperature, respiratory rate and serum concentrations of cortisol, thyroxine and triiodothyronine (T3) in normal pigs (NN) and in heterozygous (Nn) pigs with Halothane gene (n), a major gene that causes the pale, soft, exudative meat (PSE), were examined in a hot environment (32–34°C). Easily releasable myofilament content of Longissimus dorsi taken by needle biopsy was also measured as an index of myofibrillar disassembly. Rectal temperature and respiratory rate were significantly increased by the transport. However, the influence was higher (P < 0.01) in Nn pigs. Serum concentration of cortisol was increased (P < 0.01) by the transport despite the genotypes. Serum concentration of T3 was not changed by the transport in Nn pigs, whereas in NN pigs it was significantly decreased after the transport (P < 0.01). Easily releasable myofilament content after the transport was higher in Nn pigs than that of NN pigs (P < 0.05). These results suggest that response of thyroid function might relate to the stimulation of muscle proteolysis and PSE in Nn pigs under stressful conditions.