Lipid peroxidation-derived hepatotoxic aldehydes, 4-hydroxy-2E-hexenal in smoked fish meat products

ABSTRACT:   Contents of 4-hydroxy-2 E -hexenal (HHE), hepatotoxic aldehydes, in smoked fish meat products (smoked salmon and fish meat sausage) were analyzed. Large differences in these contents between the different samples were observed. Very low levels of HHE were detected in fish meat sausage samples. However, a high level of HHE was observed in one batch of smoked salmon. Changes of HHE contents in yellowtail meat containing cherry and sugi wood vinegar stored at 0°C were also analyzed for 7 days. Malonaldehyde (MA) was also analyzed in these samples as an index of the lipid peroxidation level. After 3 or 7 days of storage, HHE contents in both wood vinegar-added samples were significantly higher, but MA contents were significantly lower than those of the control.     

Effects of single and repeated heat stress on anxiety-like behavior and locomotor activity in medaka fish

In this study, we examined whether a single heat stress incident and long-term repeated heat stress could affect behavioral and neural responses in male medaka fish Oryzias latipes. By using the novel tank diving test, we found that 7-day repeated heat stress led to anxiety-like behaviors and suppressed locomotor activity, whereas fluoxetine treatment during repeated heat stress led to anxiolytic behaviors. Furthermore, a single heat stress incident increased hyper-locomotor activity. A single heat stress incident decreased mRNA expression of tryptophan hydroxylase 2 (tph2), a rate-limiting enzyme in serotonin biosynthesis, while a single heat stress increased mRNA expression of tyrosine hydroxylase 1 (th1) and tyrosine hydroxylase 2 (th2), catalyzing dopamine biosynthesis in the brain. Plasma cortisol concentration increased after a single stress, repeated stress, and fluoxetine treatment during repeated stress. These results suggest that medaka fish are a good model for assessing anxiety-like behavior induced by long-term repeated stress. Moreover, th1, th2, and tph2 in the brain would be key factors in the exploration of the central regulation of behavioral responses to a single and repeated stress in fish.

     

Molecular cloning, nucleotide sequence and characteristics of a xylanase gene (xynA) from Ruminococcus albus 7

A 2.6-kb DNA fragment encoding a xylanase gene ( xyn A) was cloned from the rumen hemicellulolytic bacterium Ruminococcus albus 7. The deduced primary structure of the protein (XynA) was divided into a signal peptide region and 3 domains. Domain A was identified as a family 11 (G) catalytic domain, but one amino acid residue was replaced by another in an active site signature 1 of family 11. Domain B is a stabilizing domain for the catalytic domains of families 10 and 11. Deletion of domain B reduced stability of the xylanase at high temperature and at high and low pH. Domain B may be useful for protein engineering of xylanase. Domain C has sequence similarity to deacetylases and NodB proteins.     

Glomus tumor of the liver in a cow

An 11-year-old Holstein-Friesian cow exhibited anorexia and jaundice. A large mass was found in the liver during necropsy. Macroscopically, the mass was composed of dark red multilobular tissue and a centrally located abscess, which was connected to the hepatic duct. Histologically, the mass consisted of proliferation of small neoplastic cells and was demarcated from the hepatic parenchyma by a thick region of granulation tissue. The neoplastic cells were predominantly arranged in solid sheets, but they also formed blood-filled cancellous structures, and proliferating foci were seen around blood vessels. Periodic acid-Schiff reaction demonstrated that a fine basement membrane-like structure surrounded the neoplastic cells. Immunohistochemically, the neoplastic cells were positive for vimentin and alpha smooth muscle actin and negative for cytokeratin, factor VIII-related antigen, chromogranin and desmin. Based on its histopathological features, the hepatic neoplasm was diagnosed as a primary glomus tumor. This is the first report about a primary glomus tumor of the liver in a cow.     

Starch Properties of the Sago Palm (<Emphasis Type="Italic">Metroxylon sagu</Emphasis> Rottb.) in Different Soils

We investigated the relationships between starch concentrations and activities of starch synthetic enzymes in sago palms (Metroxylon sagu Rottb.) under acid sulfate and mineral soil conditions. Plants grown naturally that had reached their maturated stage were sampled. We found that the growth in acid sulfate soil is lower than that in mineral soil and that starch granules were larger and there was more amylase activity in acid sulfate soil than in mineral soil. Lower amylase activity in mineral soil could eliminate the degradation of starch, making the smaller granules suitable for storing large amounts of starch in a limited space inside cells.     

Ecological functions of persistent Japanese cedar litter in structuring stream macroinvertebrate assemblages

Stream macroinvertebrate assemblages are expected to be affected by the abundance and constitution of litter from surrounding forests. We compared forest floor cover, overland flow, stream environment, and stream macroinvertebrate assemblages between the catchments of a Japanese cedar plantation (CP) and a primary deciduous forest (DF). Both systems experience excessive deer browsing. Understory vegetation cover was higher in the DF than in the CP in summer, although cover was low (<20 %), possibly because of excessive deer browsing. Litter cover was much higher in the CP than in the DF in summer as a result of the long abscission period, slow breakdown, and low rate of dispersal of Japanese cedar litter compared to deciduous litter. Monthly overland flow was always lower in the CP than in the DF, and substrate size was smaller in the DF stream. In the CP, cedar litter accumulated in the stream, probably because of its low breakdown rate and morphology, and abundant shredder taxa characterized the macroinvertebrate assemblage. In contrast, abundant burrower taxa characterized the macroinvertebrate assemblage in the DF stream. These results imply that Japanese cedar litter functions in structuring the macroinvertebrate assemblage by supplying persistent food resources for detritivores, and by buffering fine sedimentation via overland flow under excessive deer browsing.     

Differential Effects of Continuous Exposure to the Investigational Metastin/Kisspeptin Analog TAK-683 on Pulsatile and Surge Mode Secretion of Luteinizing Hormone in Ovariectomized Goats

The aim of the present study was to determine if the estradiol-induced luteinizing hormone (LH) surge is influenced by the constant exposure to TAK-683, an investigational metastin/kisspeptin analog, that had been established to depress the pulsatile gonadotropin-releasing hormone (GnRH) and LH secretion in goats. Ovariectomized goats subcutaneously received TAK-683 (TAK-683 group, n=6) or vehicle (control group, n=6) constantly via subcutaneous implantation of an osmotic pump. Five days after the start of the treatment, estradiol was infused intravenously in both groups to evaluate the effects on the LH surge. Blood samples were collected at 6-min intervals for 4 h prior to the initiation of either the TAK-683 treatment or the estradiol infusion, to determine the profiles of pulsatile LH secretion. They were also collected at 2-h intervals from –4 h to 32 h after the start of estradiol infusion for analysis of LH surges. The frequency and mean concentrations of LH pulses in the TAK-683 group were remarkably suppressed 5 days after the start of TAK-683 treatment compared with those of the control group (P<0.05). On the other hand, a clear LH surge was observed in all animals of both groups. There were no significant differences in the LH concentrations for surge peak and the peak time of the LH surge between the TAK-683 and control groups. These findings suggest that the effects of continuous exposure to kisspeptin or its analog on the mechanism(s) that regulates the pulsatile and surge mode secretion of GnRH/LH are different in goats.