Blood parameters and electrocardiogram in squeezed fish simulating the effect of net damage and recovery

ABSTRACT:   In the present study, rubber bands were tied around the girth of rainbow trout Oncorhynchus mykiss to simulate and assess the physiological damage and survival rates of fish that encounter gill nets. Physiological condition was assessed by analysis of blood lactate, pH, oxygen partial pressure and plasma potassium concentration before and after release from binding. Twenty-four hours after release, half of the test fish had died. Although the binding forces used to hamper fish did not differ significantly, blood lactate levels in the dead fish rose to 10-fold higher than those in the survivors. Consequently, the pH level fell in the group that died, whereas in the surviving group it fell only slightly and soon recovered. Potassium concentration increased after release from binding in fish that died, and the P o ₂ levels in these fish continued to drop until just before death. It was concluded that when fish get entangled in fishing nets, blood lactate accumulates because of physical fatigue and the elevated lactate levels lead to metabolic acidosis. Finally, fatal metabolic conditions could cause higher mortality rates, even in escapees.     

Possible implication of metalloproteinases in post-mortem tenderization of fish muscle

ABSTRACT: It is suspected that the proteolytic breakdown of extracellular matrix proteins is responsible for the postmortem tenderization of fish muscle during chilled storage. In order to identify the type(s) of proteinases involved in this phenomenon, the effect of proteinase inhibitors, EDTA (ethylenediamine tetraacetic acid), 1,10-phenanthroline, ρ-APMSF [(ρ-amidinophenyl) methanesulfonyl fluoride hydrochloride] and E-64 [ L - trans -epoxysuccinyl-leucylamido-(4-guanidinobutane)] on tenderization was investigated by using Japanese flounder. Proteinase inhibitor solution was injected into a blood vessel in a caudal portion of live flounder and the firmness of muscle was then evaluated as a shear force value at 0 h and 6 h after death. Metalloproteinase inhibitors, EDTA and 1,10-phenanthroline, significantly suppressed postmortem tenderization. These findings suggest that metalloproteinases are candidates for proteinases involved in the postmortem tenderization of fish muscles. Although not significantly, p -APMSF, a serine proteinase inhibitor, partially suppressed muscle tenderization, which suggests that serine proteinases are also implicated in postmortem tenderization. A cysteine proteinase inhibitor, E-64, showed no effect, suggesting that cysteine proteinases are not involved.     

Species-barrier on the cross-species oral transmission of bovine AA amyloidosis in mice

In AA amyloidosis, cross-species oral transmission has been demonstrated in several animal models. While it is known that the transmission efficiency of AA amyloidosis between different species is lower than that among the same species, the mechanism of this species-barrier is unclear. In this study, we found at first that mice orally given a large amount of bovine AA simultaneously with inflammatory stimulation did not develop AA amyloidosis. Therefore, we hypothesized that the low efficiency of the cross-species oral transmission of AA amyloidosis might be due to the low absorption rate in Peyer’s patches. To evaluate the hypothesis, we next investigated whether bovine AA was taken up by Peyer’s patches and translocated to other organs in vivo and ex vivo models. The direct absorption of bovine AA by Peyer’s patches was not observed. Besides, translocation of bovine AA to the mesenteric lymph nodes, spleen, liver, or kidney was not observed except the mesenteric lymph node of a single mouse. Thus, absorption of bovine AA by Peyer’s patches occurred much less efficiently in mouse models of cross-species oral transmission of AA amyloidosis. The present study suggests that the less efficient amyloid uptake by Peyer’s patches may be involved in the species-barrier of oral transmission of AA amyloidosis.     

Effects of elevated CO2 concentration on growth, annual ring structure and photosynthesis in Larix kaempferi seedlings

We evaluated the effects of elevated carbon dioxide concentration ([CO2]) and two nutrient regimes on stem growth rate, annual ring structure and temporal variations in photosynthetic characteristics of seedlings of Japanese larch (Larix kaempferi (Lamb.) Carr.). Seedlings were grown in phytotron chambers in an ambient (360 ppm) or an elevated (720 ppm) [CO2] in two nutrient regimes for one growing season. Elevated [CO2] reduced stem height and increased stem basal diameter compared with ambient [CO2]. The effect of elevated [CO2] on growth tended to be greater at high-nutrient supply than at low-nutrient supply. Elevated [CO2] had no significant effect on ring width or the number of tracheids per radial file. There was no obvious difference in cell wall thickness or the relative area of the cell wall between seedlings grown in ambient or elevated [CO2]. Although growth in elevated [CO2] resulted in a slight increase in cell diameter, the increase had a relatively minor effect on the relative area of the cell wall. Net assimilation rate increased in response to elevated [CO2]; however, the increase in whole-crown photosynthetic rate (Total Agrowth) in seedlings in the elevated [CO2] treatment was minimal because of the smaller specific needle area and acclimation of the photosynthetic characteristics of the needles to the growth [CO2]. In conclusion, we observed no obvious enhancement in the capacity for carbon fixation in Japanese larch seedlings grown in the presence of elevated [CO2] that might be attributable to changes in stem growth. However, elevated [CO2] caused changes in the temporal pattern of stem growth and in some anatomical features of the tracheids.     

中国笋用竹的栽培优选种

在中国534个竹子种类中，遴选了153种笋用竹。其中刚竹属、箭竹属、牡竹属、寒竹属、香竹属和绿竹属占据笋用竹种类的78％。在笋用竹中，56种具有商业价值，其中的16种具有世界市场。通过对所有笋用竹的商业价值、形态特征、生态特征和种植特点的种植潜力指数评价，将笋用竹分为5个类别：第一类（9种）具有很高的商业价值，大面积种植前景，第二类（33种）可以区域性种植。     

微通道乳化法制备单分散W/O型乳状液及液滴形成特性的影响因素

该文提出了树脂微通道乳化法生产单分散的油包水(W/O)型乳状液，研究了分散相压力、连续相黏度、乳化剂种类对乳状液生成特性的影响。结果表明，在液滴稳定形成压力范围内，随着分散相压力的提高，平均粒径增大，变动系数增大但小于10%，低于临界压力P_min和高于临界压力P_max，无法形成单分散的乳状液；连续相黏度越大，生成的乳状液粒径越大，变动系数越高；所使用的乳化剂中，聚甘油多聚蓖麻醇酸酯适合生产单分散的W/O型乳状液，生成的乳状液粒径42～60 μm，变动系数10%以下；使用甘油单油酸酯、磷脂类乳化剂时，虽然能形成液滴但很快发生凝集、聚合现象；当使用蛋白质类乳化剂时，基板被润湿，分散相连续流出不形成液滴，单分散的油包水型乳状液无法形成。     

Unchanged Distribution Density of Anionic Sites on the Glomerular Wall in Rats with Active Heymann Nephritis

In various kinds of glomerulonephritis, alteration of anionic charge on the glomerular basement membrane (GBM) and podocytes has been controversial for more than decade. To elucidate the relation between glomerular protein leakage and anionic sites on the glomerular wall, we examined the distribution of anionic sites on the GBM and podocytes of rats with active Heymann nephritis (AHN). Urinalysis for protein levels was conducted, and the kidneys were examined using electron microscopic cytochemistry for the assessment of anionic charge with two cationic probes. The anionic sites on podocytes were decreased in number in the AHN rats; however, the distributions of anionic sites on the GBM were similar in density to those seen in the control animals. From these results, we consider that the decrease in anionic charge density on podocytes might be attributable to protein leakage and that the charge barrier of the GBM is irrelevant to the protein leakage in AHN rats.