Comparative study on extractive components of fresh and boiled gonads of three species of sea urchins from the Gulf of Thailand

Proximate compositions and extractive components of the gonads (roes) of three species of sea urchins, namely, Diadema setosum, Salmacis sphaeroides and Toxopneustes pileolus, from the Gulf of Thailand were identified and the boiling effect on these extractive components of these sea urchin roes studied. Of the three species tested, the gonads of D. setosum had the lowest moisture (62 %) and ash (2 %) contents and the highest protein (15 %) and lipid (11 %) contents. Major extractive constituents of the roes of D. setosum were taurine, arginine, lysine, glycine, tyrosine, valine, leucine, isoleucine, alanine, glutamic acid and inosine 5′-monophosphate; those for the roes of S. sphaeroides were glycine, lysine, alanine, arginine, ATP and adenosine 5′-diphosphate; those for the roes of T. pileolus were glycine, alanine, serine, ATP and adenosine 5′-monophosphate, respectively. Boiling in 3 % brine (98–100 °C, 2 min) drastically reduced the amounts of both free amino acids and ATP-related compounds of sea urchins belonging to all these species.     

Antioxidative activities of a mycosporine-like amino acid,porphyra-334

Antioxidative activities of porphyra-334, a mycosporine-like amino acid extracted from laver were evaluated. Oxidation of linoleic acid induced by an alkyl-radical 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) was successfully suppressed by porphyra-334 (0–200 μM). The simultaneous application of 0.02 μM α-tocopherol and 50 μM porphyra-334 effectively suppressed the AAPH induced oxidation level to approximately 40% of a single application of porphyra-334 after 10 min reaction. Porphyra-334 (0–200 μM) efficiently suppressed the lipid peroxidation induced by singlet oxygen although the antioxidative effect observed was relatively moderate at the initial stage of oxidation. These results suggested that porphyra-334 may function as an antioxidant which influences the storage stability of laver.     

Changes in physical properties of heat-induced gel on addition of gluconate associated with suppression of myosin denaturation in walleye pollack salt-ground <Emphasis Type="Italic">surimi</Emphasis> during preheating

Changes in physical properties of two-step heated gels on addition of gluconate were investigated in terms of relationships between breaking strength and gel stiffness. Regression lines between the breaking strength and the gel stiffness were extended to the x-axis (gel stiffness), and the intercept was defined as S_BSO. The S_BSO of the two-step heated gels increased with gluconate contents in salt-ground surimis, suggesting that the harder but less elastic gels formed on addition of gluconate were dose-dependent. Conversely, the denaturation rate constants of myosin in salt-ground surimis during preheating estimated by means of Ca-ATPase inactivation, loss of salt solubility, and decrease of denaturant solubility were considerably reduced by gluconate. Thus, the progress of myosin denaturation was strongly suppressed. Increments of S_BSO (δS_BSO) of the two-step heated gels on addition of gluconate were inversely correlated with the denaturation rate constants of myosin in salt-ground surimis for every index. Thus, the changes in physical parameters of two-step heated gel caused by gluconate may be associated with the sluggish progress of myosin denaturation in salt-ground surimi during preheating.     

Lack of hepatocarcinogenicity of 2,2’-[1,2-ethanediylbis(oxymethylene)]bis-oxirane, 3-hydroxy-2-naphthoic acid,and acetoacetanilide in a medium-term rat liver bioassay

The carcinogenicity of 2,2’-[1,2-ethanediylbis(oxymethylene)]bis-oxirane (ethylene glycol diglycidyl ether; EGDE), 3-hydroxy-2-naphthoic acid (HNA), and acetoacetanilide (AAA) was investigated using a medium-term rat liver bioassay for an occupational safety assessment. F344 male rats were administered a single intraperitoneal injection of diethylnitrosamine (200 mg/kg body weight (bw)/day) and then starting 2 weeks later, they received EGDE at 6, 20, and 60 mg/kg bw/day, HNA at 20, 60, and 200 mg/kg bw/day, or AAA at 60, 200, and 600 mg/kg bw/day by oral gavage for 6 weeks. The animals in the positive control group received phenobarbital sodium solution (PB, 25 mg/kg bw/day) by oral gavage and those in the negative control group received a vehicle (water/corn oil) during the administration period of test substances in this model. All animals were subjected to two-thirds partial hepatectomy at week 3 and euthanized at week 8. Neither the number nor the area of hepatocellular foci positive for glutathione S-transferase placental form (GST-P) increased in any of the EGDE, HNA, or AAA treated groups. However, the number and area of GST-P-positive foci significantly increased in the positive control group treated with PB. The results indicate that EGDE, HNA, and AAA lack hepatocarcinogenicity in rats.     

The secretory pattern and source of immunoreactive prolactin in pregnant African (Loxodonta africana) and Asian (Elephas maximus) elephants

The objective of the present study was to define the secretion of prolactin (PRL) in pregnant African and Asian elephants. Levels of immunoreactive (ir-) PRL in serum and placental homogenates were measured by a heterologous radioimmunoassay (RIA) based on an ovine and human RIA system, and the localization of ir-PRL in the placenta was detected by immunohistochemistry using anti-human PRL. Circulating ir-PRL clearly showed a biphasic pattern during pregnancy in African and Asian elephants. Serum levels of ir-PRL started to increase from the 4 - 6th month of gestation and reached the first peak level around the 11-14th month. A second peak of circulating ir-PRL levels was observed around the 18-20th month of gestation followed by an abrupt decline after parturition. In contrast, in a case of abortion of an African elephant, the second peak of ir-PRL was not observed, and the levels remained low for about four months until parturition. The weight of the fetus delivered at the 17th month of gestation was 23.5 kg, which was quite small compared with normal fetuses in previous reports. Ir-PRL was detected in placental homogenates, and immunolocalization was observed in trophoblasts in both the African and Asian elephants, indicating that the placenta is the source of ir-PRL during pregnancy in elephants. The present results clearly demonstrated that circulating ir-PRL shows a biphasic pattern during normal pregnancy and that the placenta appears to be an important source of circulating ir-PRL during pregnancy in both African and Asian elephants.     

New method to determine the hydroxyl value in liquefied bark as Polyurethane material

Conclusions When the hydroxyl values of materials containing phenolic 3 or sterically hindered hydroxyl groups were determined by the esterification method, the values were considerably smaller than the theoretical values. In contrast, the NCO method provided hydroxyl values much closer to the theoretical values for such materials, though the values varied depending on the kinds and amounts of catalysts.The quantity of hydroxyl groups reacting with the NCO group could be directly determined by the NCO method using a catalyst mixture consisting of DABCO and DBTDL in a molar ratio of 21. Therefore, this method can be considered useful for determining the hydroxyl value before preparing polyurethane from liquefied wood or bark.Part of this paper was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 1988     

Inhibitory effect of a quercetin metabolite, quercetin 3-O-beta-D-glucuronide, on lipid peroxidation in liposomal membranes.

To study the antioxidant activity of quercetin 3-O-beta-D-glucuronide (Q3GA), which is one of the quercetin metabolites in the blood after intake of quercetin-rich food, the inhibitory effect of Q3GA on lipid peroxidation was estimated using phosphatidylcholine large unilamellar vesicles (PC LUV) as a biomembrane model. Iron ion, an aqueous peroxyl radical generator, a peroxynitrite generator, or lipoxygenase was used as the inducer of lipid peroxidation. In all cases, Q3GA inhibited lipid peroxidation significantly, although its inhibitory effect was lower than that of quercetin aglycon. The ultrafiltration of PC LUV containing Q3GA revealed that Q3GA has low but significant affinity with the membranes of phospholipid bilayers. It is therefore likely that Q3GA acts as an efficient antioxidant in membranous lipid peroxidation through its localization in the phospholipid bilayer. This conjugated quercetin metabolite seems to retain the ability to protect cellular and subcellular membranes from peroxidative attack by reactive oxygen species and peroxidative enzymes.     

Effects of addition of sodium lauryl sulfate on frozen-thawed canine spermatozoa

The addition of Orvus ES paste (OEP) to extender may be essential for preparing frozen dog semen. The major ingredient of OEP is sodium lauryl sulfate (SLS). In this study, we compared the effect of SLS on frozen dog semen with that of OEP. There were no significant differences between the 2-mg/ml SLS group and OEP group concerning sperm motility, viability and the percentage of viable sperm with intact acrosomes after freeze-thawing. These results suggest that the effectiveness of frozen dog semen extender containing 2 mg/ml of SLS is similar effective to that demonstrated for OEP.     

Effects of liquid nitrogen vapor sensitization conditions on the quality of frozen-thawed dog spermatozoa

The freezing conditions for preparation of frozen canine semen by the plunging method were investigated with regard to the period of sensitization in liquid nitrogen (LN2) vapor and the height from LN2, and the semen qualities after thawing were compared with those of canine semen prepared by the simple freezer method previously reported by us. In the plunging method, 9 semen straws were prepared under the same conditions, horizontally kept at 5, 7, and 10 cm above the LN2 surface in a styrene foam box for 5, 10, and 15 min, and then plunged into LN2. The semen qualities immediately after thawing were high in the 7 cm/10 min (cooling rate: -4 to -22 degrees C/min) and 10 cm/15 min groups (cooling rate: -6 to -10 degrees C/min). On comparison of frozen semen prepared by the plunging method (7 cm/10 min) with frozen semen prepared by the simple freezer method, sperm motility and viability were significantly higher for the frozen semen prepared by the plunging method. The cooling rate in freezing was higher for the simple freezer method (cooling rate: -6 to -50.9 degrees C/min) than the plunging method. Based on these findings, horizontal placement of canine semen straws above LN2 to reduce the temperature at a slow cooling rate of about -10 degrees C/min, followed by plunging into LN2 after sensitization for 10-15 min, provides good semen qualities after thawing.