冻结条件下冻藏温度对鲢鱼肉肌原纤维蛋白冷冻变性的影响

本研究探讨了不同冻结终温、冻结速率以及冻结贮藏温度下鲢鱼肉肌原纤维蛋白ATPase活性的变化。结果表明，冻结终温和冻结速率肌球蛋白变性的影响较小，即使在慢速冻结（从0℃经过72h冻结到－40℃）下，样品肌原纤维蛋白的Ca^2＋－、Mg^2＋－、EDTA－ATPase活性的变化都很小。在贮藏过程中，贮藏温度越低肌原纤维蛋白越稳定，而慢冻和快冻对于其后冻藏过程中肌原纤维蛋白变性的差异也不显著。与冻结速率和浆结终温相比，冻结贮藏温度的影响明显。     

Virulence of infectious pancreatic necrosis virus is associated with the larger RNA segment (RNA segment A)

Abstract. Infectious pancreatic necrosis virus (IPNV) contains two segments of double- stranded RNA (the larger RNA segment, A; and a smaller RNA segment, B). The IPNV- Buhl isolate belongs to the VR299 serotype, and eel virus European (EVE) is serologically the same as the Ab serotype. IPNV-Buhl is virulent to rainbow trout fry, Oncorhynchus mykiss (Walbaum), whereas EVE is avirulent. To determine the genetic basis for the difference of the virulence, intertypic reassortants were made between IPNV-Buhl and EVE. The reassortants with the genotypes of P/E (segment A of IPNV-Buhl and segment B of EVE) and E/P (segment A of EVE and segment B of IPNV-Buhl) were studied for their pathogenicity to rainbow trout fry. The P/E reassortant was highly virulent, similar to the IPNV-Buhl parent (P/P), while the E/P reassortant was avirulent, as was the EVE parent (E/E). A high level of viral replication was observed in almost all organs of the fry infected with the P/E reassortant and the IPNV-Buhl parent. In contrast, viral replication was restricted to the epidermal cells of the fry infected with the E/P reassortant and the EVE parent. The results demonstrate that the larger RNA segment (RNA segment A) of IPNV is related to cell tropism in vivo and is responsible for virulence in rainbow trout fry.     

Immunological characteristics and response to lipopolysaccharide of mouse lines selectively bred with natural and acquired immunities

Genetic improvement of resistance to infectious diseases is a challenging goal in animal breeding. Infection resistance involves multiple immunological characteristics, including natural and acquired immunity. In the present study, we developed an experimental model based on genetic selection, to improve immunological phenotypes. We selectively established three mouse lines based on phagocytic activity, antibody production and the combination of these two phenotypes. We analyzed the immunological characteristics of these lines using a lipopolysaccharide (LPS), which is one of the main components of Gram‐negative bacteria. An intense immunological reaction was induced in each of the three mouse lines. Severe loss of body weight and liver damage were observed, and a high level of cytokine messenger RNA was detected in the liver tissue. The mouse line established using a combination of the two selection standards showed unique characteristics relative to the mouse lines selected on the basis of a single phenotype. Our results indicate that genetic selection and breeding is effective, even for immunological phenotypes with a relatively low heritability. Thus, it may be possible to improve resistance to infectious diseases by means of genetic selection.     

冻结条件下冻藏温度对鲢鱼肉肌原纤维蛋白冷冻变性的影响

本研究探讨了不同冻结终温、冻结速率以及冻结贮藏温度下鲢鱼肉肌原纤维蛋白ATPase活性的变化。结果表明，冻结终温和冻结速率肌球蛋白变性的影响较小，即使在慢速冻结（从0℃经过72h冻结到－40℃）下，样品肌原纤维蛋白的Ca^2＋－、Mg^2＋－、EDTA－ATPase活性的变化都很小。在贮藏过程中，贮藏温度越低肌原纤维蛋白越稳定，而慢冻和快冻对于其后冻藏过程中肌原纤维蛋白变性的差异也不显著。与冻结速率和浆结终温相比，冻结贮藏温度的影响明显。