Degradation of myofibrils in cultured yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis> burnt meat: effects of a myofibril-bound EDTA-sensitive protease

“Burnt meat” is a term used to describe the white (pale, grainy, exudative) muscle of yellowtail or tuna. It (with lightness parameter, L* ≥ 55) was observed after 2 h storage in the suffocate in air (SA) 29°C group and after 4 h storage in the spinal cord destruction (SCD) 29°C group. In the SA 17°C group, burnt meat was also observed after 4 h storage. In contrast, the meat in the SCD 17°C group was normal until after 12 h storage. The myosin heavy chain (MHC) was more degraded than the other myofibrillar proteins, and some protein bands increased in the burnt meat. The protease that leads to the degradation of MHC was investigated using myofibrils from the meat. EDTA completely suppressed the degradation, indicating that a myofibril-bound EDTA-sensitive protease (MBESP) may exist in yellowtail muscle and this caused the degradation of MHC. The optimum pH and temperature of MBESP in yellowtail were 5.0 and 50–60°C, respectively.     

Determinants of the daily rhythm of blood fluidity

Background  

Numerous processes in the living body exhibit daily rhythmicity. In this study, we characterized a daily rhythm of blood fluidity and identified its determinants.     

An efficient molecular technique for sexing tiger pufferfish (fugu) and the occurrence of sex reversal in a hatchery population

The tiger pufferfish (fugu) is one of the most important food fishes in East Asia. Since its testes are regarded as a delicacy, sex determination is economically relevant. Previous studies have identified a missense single-nucleotide polymorphism (SNP) in the Amhr2 (anti-Müllerian hormone receptor type II) gene as a strong candidate for a master sex-determining polymorphism. To distinguish genotypic sex efficiently, we developed a high-resolution melting (HRM) assay for this SNP site. By screening 396 fish from two independent crosses reared under controlled conditions, we observed perfect concordance between the SNP genotype and phenotypic sex. Thus, this method holds great potential for use in high-throughput sexing. When analyzing 293 progeny from a third cross reared under unknown conditions, we unexpectedly found that 25 % of phenotypic males exhibited female genotype. These results suggest that environmental factors such as rearing conditions could influence the sex-determination pathway in pufferfish. Alternatively, genetic modifiers might override the signals from Amhr2. This finding raises a concern regarding enhanced stock management of this species, because sex-reversed fish could compromise the sex ratio in subsequent generations. The HRM assay will also be useful for monitoring the degree of sex reversal before release.     

Effects of acidic fog and ozone on the growth and physiological functions of Fagus crenata saplings

The effects of simulated acid fog (SAF) and ozone (O₃) stress on the growth and physiology of beech (Fagus crenata) saplings were investigated. Three-year-old beech saplings were exposed to SAFs of pH 3 and pH 5 (control) during May 2007 to July 2008. In each SAF treatment group, half of the saplings were exposed to 60 ppb of O₃ during September 2007 to July 2008. In comparison to the control saplings, those from the pH 3 treatment had lower total plant biomasses, epicuticular wax amounts, Ca²⁺ concentrations in their leaves, and lower starch concentrations in their leaves and roots. The effect of O₃ was significant only for the starch concentration in the roots, but the O₃ exposure also negatively affected the growth and physiology of beech saplings. Results show that acid fog exerts various severe effects, and that both chronic acid fog and O₃ exposure suppressed the physiological functions of beech saplings.     

Maturation-associated changes in internal distribution and intra-ovarian microdistribution of tetrodotoxin in the pufferfish <Emphasis Type="Italic">Takifugu pardalis</Emphasis>

To clarify the maturation-associated accumulation profile of tetrodotoxin (TTX) in the female pufferfish Takifugu pardalis, specimens collected from Omura Bay, Nagasaki Prefecture, Japan, from November through December, 2014, were separated based on the histology of ovarian sections into four groups: yolk vesicle stage (Yv), yolk globule stage (Yg)-1, Yg-2, and Yg-3. TTX quantification in each tissue in each group by liquid chromatography–mass spectrometry revealed that the TTX concentration [mouse unit (MU)/g] in the ovary increased from Yv to Yg-1, and the TTX amount (MU/individual) in the ovary increased from Yg-1 through Yg-3. In Yv, TTX in the skin accounted for 86% of the total TTX in the body, whereas from Yg-1 through Yg-3, ovarian TTX accounted for 53–76% of the total. In female specimens collected from the same bay from February to May 2015, the TTX amount in the ovary markedly decreased after spawning, and the TTX amount in the liver increased. Immunohistochemical observation of the ovarian sections indicated that TTX localized mainly in the nucleus of immature oocytes, but then distributes to the yolk vesicles and yolk globules as maturation advances, and is partly transferred to the egg membrane as spawning approaches.     

A method for estimating radioactive cesium concentrations in cattle blood using urine samples

In the region contaminated by the Fukushima nuclear accident, radioactive contamination of live cattle should be checked before slaughter. In this study, we establish a precise method for estimating radioactive cesium concentrations in cattle blood using urine samples. Blood and urine samples were collected from a total of 71 cattle on two farms in the ‘difficult‐to‐return zone’. Urine ¹³⁷Cs, specific gravity, electrical conductivity, pH , sodium, potassium, calcium, and creatinine were measured and various estimation methods for blood ¹³⁷Cs were tested. The average error rate of the estimation was 54.2% without correction. Correcting for urine creatinine, specific gravity, electrical conductivity, or potassium improved the precision of the estimation. Correcting for specific gravity using the following formula gave the most precise estimate (average error rate = 16.9%): [blood ¹³⁷Cs] = [urinary ¹³⁷Cs]/([specific gravity] ? 1)/329. Urine samples are faster to measure than blood samples because urine can be obtained in larger quantities and has a higher ¹³⁷Cs concentration than blood. These advantages of urine and the estimation precision demonstrated in our study, indicate that estimation of blood ¹³⁷Cs using urine samples is a practical means of monitoring radioactive contamination in live cattle.     

Current status of commercial Calibrachoa cultivars as assessed by morphology and other traits

To study the morphological diversity of the popular ornamental crop Calibrachoa, traded since the 1990s, floral and vegetative characters of 91 commercial cultivars were compared to those of natural species. Floral colours were classified according to the ISCC-NBS system and the CIE LAB system. The numerical data obtained by measuring 19 floral and vegetative characters was tested with principal component (PC) analysis. Floral colour classes of commercial cultivars were divided into 37 groups according the ISCC-NBS system, whereas those of natural species were divided into 9 groups. These tendencies were readily observable in the scatter diagrams of the a* vs. b* values and the C* vs. L* values. As the result of PC analysis, six PCs were obtained. For PC4, which negatively correlated with the degree of nocturnal corolla limb closure, the majority of natural species showed negative scores whereas the majority of cultivars had positive PC4 scores. In terms of PC2 (flower size), PC3 (growth form), PC5 (floral shape) and PC6 (leaf shape), natural species were dispersed in a range wider than the cultivars. These results suggest that Calibrachoa cultivars possess more highly variable floral colour than natural species, and breeding programmes to diversify the floral colour seem to have progressed rapidly. The tendency of natural species to close the corolla limb toward evening has been removed almost completely from the cultivars. The floral size, growth form, floral shape and leaf shape of the cultivars were rather uniform compared to those of natural species.     

两种石斑鱼性腺分化前后脑垂体中FSHβ和LHβ细胞免疫组织化学及其基因表达

为了解石斑鱼Epinephelus性腺分化前后脑垂体中促卵泡激素(FSHβ)和黄体生产素(LHβ)细胞分布及基因含量的变化,以赤点石斑鱼Epinephelus akaara和黑边石斑鱼E.fasciatus为研究对象,采用苏木精-伊红染色法(H.E.)对孵化后55、80、120日龄幼鱼的性腺和脑垂体结构进行组织学观察,...