Influence of death struggle on the structural changes in chub mackerel muscle during chilled storage

ABSTRACT: Chub mackerel (34–35 cm, approximately 500 g), which were caught by fishing with a rod and line at the Bungo Channel, Oita prefecture, were rested overnight in a fish preserve and either killed by decapitation (control group) or allowed to struggle in air for 30 min (struggled group). Muscle samples were excised every 4 h, and measurements on breaking strength and histological observations were done for both groups. The breaking strength of muscle in the control group was significantly higher than that in the struggled group, whereby a decrease in breaking strength was delayed for 12 h compared to the struggled group. Light microscopy showed space extension among muscle cells in association with a decrease in breaking strength. Especially in the struggled group, the extended area was larger and the difference in area was significant at the time when breaking strength showed a significant difference. Using electron microscopy, the extended area showed cut and/or disappeared collagen fibrils. From these results, it was demonstrated that struggling to death promoted the degradation of collagen fibrils and the weakening of connective tissue and, resultantly, led to the faster softening of muscle of chub mackerel.     

Detection of Mycobacterium avium subsp. paratuberculosis in ovine faeces by direct quantitative PCR has similar or greater sensitivity compared to radiometric culture

The aims of this study were to develop a new real-time quantitative PCR (QPCR) assay based on IS900 for detection and quantification of Mycobacterium avium subsp. paratuberculosis (MAP) DNA in faeces, and to use this to detect infected sheep. Both the C and S strains of MAP were detected by the QPCR assay, and no cross reactions were detected with 51 other species of mycobacteria including 10 which contained IS900-like sequences. One copy of IS900 fragment cloned into plasmid pCR2.1 and 1 fg of MAP genomic DNA were consistently detected, while in spiked faecal samples the detection limit was 10 viable MAP per gram of ovine faeces. A total of 506 individual ovine faecal samples and 27 pooled ovine faecal samples with known culture results were tested. The QPCR assay detected 68 of 69 BACTEC culture positive individual faeces and there was a strong relation between time to detection in culture and DNA quantity measured by QPCR (r= -0.70). In pooled faecal samples, QPCR also agreed with culture (kappa=0.59). MAP DNA was detected from some culture negative faecal samples from sheep exposed to MAP, suggesting that the QPCR has very high analytical sensitivity for MAP in faecal samples and detects non-viable MAP in ovine faeces. None of the faecal samples from 176 sheep that were not exposed to MAP were positive in QPCR. This is the first report of a direct faecal QPCR assay that has similar sensitivity to a gold standard radiometric culture assay.     

Beneficial effects on meat quality of yellowtail Seriola quinqueradiata induced by diets containing red pepper

The meat quality of farmed yellowtail Seriola quinqueradiata fed on extruded pellets (EP) containing 0.5% (v/v) red pepper (experimental group) was compared with yellowtail of the same age fed on EP (control group). In 1-year-old yellowtail, the crude lipid content of the dorsal muscle of the experimental group tended to be lower than that of the control group. In contrast, there was no difference in the lipid content of the dorsal muscle between the control group and the experimental group in 2-year-old yellowtail. The muscle texture of the experimental group was significantly firmer than that of the control group, with the effect of red pepper unrelated to fish age and lipid content. Color change of red muscle of the experimental group was significantly lower than that of the control group, and the content of thiobarbituric acid-reactive substances in the red muscle was significantly lower in the experimental group than in the control group. These results are the first to demonstrate that the inclusion of red pepper in the diet is able to reduce the loss of muscle texture firmness and to slow down color change in red muscle of yellowtail.     

Establishment of a quantitative ELISA for the measurement of allergen-specific IgE in dogs using anti-IgE antibody cross-reactive to mouse and dog IgE

As IgE plays a pivotal role in type I hypersensitivity-mediated allergic diseases, it is valuable to measure absolute quantity of serum antigen-specific IgE for clinical and research purposes. Here we describe a novel ELISA system that enables quantification of antigen-specific IgE in ng/ml in dogs. A newly developed monoclonal antibody (CRE-DM) was shown to recognize canine and mouse IgE equally in a dose dependent manner, but it did not recognize canine IgG. The reactivity of CRE-DM to canine IgE was also confirmed by an inhibition ELISA using canine IgE as an inhibitor and the maximum inhibition rate was 91.3%. In order to know whether canine IgE specific to an allergen could be quantitatively measured with an ELISA using CRE-DM, we established a quantitative ELISA that could measure canine IgE recognizing Cry j 1, one of the major allergens of Japanese cedar pollen. In this ELISA, a standard curve was created by using concentration-predetermined Cry j 1-specific monoclonal mouse IgE. According to the standard curve, the concentration of Cry j 1-specific IgE in dogs that were experimentally sensitized to Japanese cedar pollen could be calculated and determined in ng/ml. The specificity of the Cry j 1-specific IgE ELISA using CRE-DM was also confirmed by inhibition ELISA using canine IgE as an inhibitor and the inhibition rate was 97.0%. Reproducibility of the ELISA in three independent assays was determined using groups of pooled canine sera whose Cry j 1-IgE titers ranged from 155.9 to 888.2 ng/ml. Intra- and inter-assay reproducibility was determined with coefficient of variation ranging between 3.1-5.2% and 2.2-8.0%, respectively. These results demonstrated that the ELISA utilizing CRE-DM was a specific, reliable and robust new laboratory test that could quantify absolute amount of antigen-specific IgE in canine serum. The ELISA will serve as a useful tool in the clinics to evaluate the change of serum IgE titers during anti-allergic treatments as well as during seasonal fluctuation of allergen exposure.     

The Complete Nucleotide Sequence of a Japanese Isolate of White clover mosaic virus Strain RC

The complete nucleotide sequence was determined for genomic RNA of White clover mosaic virus (WClMV-RC) isolated from red clover (Trifolium pratense) in Japan, It is 5843 nucleotides in length, excluding the poly(A) tail at the 3' terminus. Similar to other potexviruses, it contains five open reading frames (ORFs 1 through 5), which putatively encode an RNA-dependent RNA polymerase (RdRp) (147 kDa), a triple gene block (TGB) (26 kDa/13 kDa/7 kDa), and a coat protein (CP) (22 kDa), respectively. The deduced amino acid sequence of the WClMV-RC CP was identical to that of WClMV-O, one of two New Zealand isolates, but only 85% identical to that of WClMV-M, the other New Zealand isolate, because of heterogeneity in the C-termini of CP amino acid sequences. The implication of this CP heterogeneity is discussed. Received 30 August 2001/ Accepted in revised form 11 January 2002     

一种农杆菌介导稻瘟病菌的遗传转化

以农杆菌C58C1及携带潮霉素抗性的质粒pBIG2RHPH2为介导,以广泛不致病的野生型稻瘟病菌CY2为出发菌株,开展稻瘟病菌T-DNA插入转化条件的研究。农杆菌OD600为0.1条件下,乙酰丁香酮(AS)200μmol/L,用IM培养基(pH5.2)共培养。结果表明,在潮霉素、头孢噻肟钠和壮观霉素为200μg/mL,2mm滤纸条筛选培养,转化效率最高,平均可获得329.0个转化子/1×104个孢子。通过对转化子的继代稳定性和PCR检测,证明转化子均获得了T-DNA插入片段,且能稳定遗传。采用接种法,在不同遗传背景的44个抗稻瘟病的水稻近等基因系接种8000个转化子,获得20个致病突变体。     

Reproductive cycle and growth of the sand dollar Scaphechinus griseus inhabiting Japanese surf clam Pseudocardium sachalinense fishing grounds in Tomakomai,southwest Hokkaido,Japan

Fisheries Science - Bioturbation by the sand dollar Scaphechinus griseus is suspected to inhibit the recruitment of Pseudocardium sachalinense, a commercially important bivalve. This study aimed to...     

Settling and raising postlarval abalone Haliotis diversicolor supertexta (Lischke) on microparticulate diets embedded in a layer of alginate

Two 21 day experiments were conducted to determine whether microparticulate diets could be used to substitute for diatoms for raising (Experiment 1) as well as settling and on‐growing (Experiment 2) Haliotis diversicolor supertexta postlarvae. The experiments were conducted in 10 L flow‐through tanks and each diet had three replicate tanks. In experiment 1, three experimental microparticulate diets supplied by a commercial feed company, labelled SF‐15, SF‐15 (T) and JFY‐13–1, were used, and in experiment 2, SF‐15 and SF‐15 (T). Artificial diets were compared to diatoms in terms of supporting growth and survival. The survival rate for experiment 1 was lowest for JFY‐13–1 (0%) and highest for diatoms (12.9±0.8%). The final size of postlarvae fed SF‐15 and SF‐15 (T) was significantly greater than that of postlarvae fed diatoms, 973±193 μm and 996±220 μm compared to 786±141 μm. In experiment 2, a total number of 501 larvae settled onto plates covered with SF‐15, 254 on SF‐15 (T) and 1085 on diatoms. The highest survival rate was 33.1±6.9% for SF‐15 and the lowest was 17.3±5.0% for diatoms. However, the final length of postlarvae fed diatoms was significantly greater than SF‐15 and SF‐15 (T); 1018±379 μm compared to 728±89 μm and 717±90 μm. The artificial micro diets used in this study were comparable to diatoms in terms of grow and survival of postlarval H. diversicolor supertexta.     

Nonrandom distribution of chum salmon stocks in the Bering Sea and the North Pacific Ocean estimated using mitochondrial DNA microarray

More than 1,000 age-identified chum salmon Oncorhynchus keta collected at 23 stations in the Bering Sea and the North Pacific Ocean in June to July 2003 were used to estimate their origin of stocks using a DNA microarray developed for analyzing the mitochondrial (mt)DNA haplotypes. The observed haplotype distribution was nearly the same as that reported previously for fish collected in September 2002 and 2003 in the present surveyed areas. A conditional maximum-likelihood method for estimation of stock compositions indicated that the Japanese stocks mainly distributed in north central Bering Sea, whereas the Russian stocks were mainly in western Bering Sea. The North American stocks were abundant in eastern Bering Sea and around the Aleutian Islands. Such an area-specific stock composition was not significantly different between mature and immature fish. Thus, the combined results of 2 years suggest that the distribution of chum salmon is nonrandom in the surveyed areas in summer and autumn, and that fish of the same origin migrate together to the same area irrespective of age.     

Radiocarbon Content in Urban Atmospheric Aerosols

We attempted to elucidate seasonal variations in fossil-fuel-derived carbon (FC) and biomass-derived carbon (BC) in urban atmospheric aerosols. We undertook continuous measurements of the composition of fine particle (PM_2.1) in central Tokyo, including the ¹⁴C/¹²C ratio. The percent modern carbon (pMC) contained in all samples averaged 43, and the highest was 54 in late December and the lowest was 31 in early August. From the observed carbonaceous component concentrations and the pMC we could calculate the content ratio of FC and BC in PM_2.1 and investigate their seasonal variations. Although there was almost no seasonal variation in the ratio of FC, the ratio of BC was observed to rise in early winter. This indicates that FC is influenced by the emission sources without seasonal variations (such as automobiles driven in urban areas). Furthermore, there is significant correlation between BC and organic carbon (OC), and even for urban areas, it is considered that the contribution of biomass carbon to OC in PM_2.1 is high.