Intramolecular carbon isotope distribution of acetic acid in vinegar

Compound-specific carbon isotope analysis of acetic acid is useful for origin discrimination and quality control of vinegar. Intramolecular carbon isotope distributions, which are each carbon isotope ratios of the methyl and carboxyl carbons in the acetic acid molecule, may be required to obtain more detailed information to discriminate such origin. In this study, improved gas chromatography-pyrolysis-gas chromatography-combustion-isotope ratio mass spectrometry (GC-Py-GC-C-IRMS) combined with headspace solid-phase microextraction (HS-SPME) was used to measure the intramolecular carbon isotope distributions of acetic acid in 14 Japanese vinegars. The results demonstrated that the methyl carbons of acetic acid molecules in vinegars produced from plants were mostly isotopically depleted in (13)C relative to the carboxyl carbon. Moreover, isotopic differences (δ(13)C(carboxyl) - δ(13)C(methyl)) had a wide range from -0.3 to 18.2‰, and these values differed among botanical origins, C3, C4, and CAM plants.     

Optimum insurance contract of flood damage index insurance for rice farmers in Myanmar

Climate change is an underlying cause of many extreme events such as enormous cyclones and erratic torrential rains. These phenomena threaten farmers in coastal regions of Myanmar. Self-insurance through means such as crop diversification is insufficient for sustainable farm management. Weather index insurance (WII) is receiving much attention because of its low management costs. An optimum WII contract for flood damage using rainfall as the index has been proposed for rice farmers in coastal regions. According to the model, an insurance payment demand function is derived by solving the expected utility maximization problem. The utility function of the contract is specified as constant relative risk aversion type. The production function is specified as Cobb–Douglas type. By substituting real average data of rice production of farmers into this function, the optimum insurance payment and premium are obtained. Changes in insurance compensation by payments according to an increase in the price of rice, rainfall, and degree of risk aversion are investigated. Results suggest that if an average farmer pays around 41.5 US dollars per year, then farm management will be optimally stabilized under the flood risk.

     

Thyroid hormones in eggs of various freshwater,marine and diadromous teleosts and their changes during egg development

Thyroid hormone concentrations in unfertilized eggs of 26 species of various freshwater, marine and diadromous teleosts were examined, together with changes in their concentrations during egg development in some species. Significant quantities of both thyroxine (T₄) and triiodothyronine (T₃) were found in eggs of all species examined. Mean T₄ and T₃ concentrations in eggs varied from 0.04 (marbled sole) to 15.00 ng/g (chum salmon), and from 0.07 (goldfish) to 9.95 ng/g (Pacific herring), respectively. T₄ concentrations were significantly greater than T₃ concentrations in eggs of most freshwater fishes, whereas T₃ concentrations were greater in seawater fishes. During the course of development, thyroid hormones in eggs decreased markedly before hatching. These findings suggest that thyroid hormones are consistently present in teleost eggs, and thus may play an important role in the egg development.     

Stimulation of insulin-like growth factor-I production by recombinant bovine growth hormone in Mozambique tilapia, Oreochromis mossambicus

We have previously reported growth-promoting effects of recombinant bovine growth hormone (rbGH) in Mozambique tilapia, Oreochromis mossambicus, after 4 weekly injections or a single injection of slow-releasing formulation (Posilac^®) (Leedom et al. 2002). In order to obtain further understanding of the role of the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis in growth in the tilapia, the effects of rbGH on plasma and mRNA levels of IGF-I were examined. Plasma IGF-I levels were significantly increased after rbGH and Posilac^® injections, and a significant correlation was observed between plasma IGF-I levels, body length and mass in both treatments. IGF-I mRNA levels in the liver and in the skeletal muscle were also significantly increased after rbGH and Posilac^® injections, indicating that IGF-I gene expression in these tissues is under control of circulating GH. IGF-I mRNA levels in the gill were not affected by treatment. Liver IGF-I mRNA levels were significantly correlated with body length and with body mass after rbGH and Posilac^® injections. These results indicate that the growth-promoting effect of rbGH in this species is mediated to a significant extent via its stimulation of hepatic production of IGF-I and the resulting increase in plasma IGF-I, and also possibly through locally produced IGF-I in the skeletal muscle, acting in a paracrine or autocrine fashion.     

Disparate effects of gonadal steroid hormones on plasma and liver mRNA levels of insulin-like growth factor-I and vitellogenin in the tilapia, Oreochromis mossambicus

The tilapia, Oreochromis mossambicus, exhibits a sexually dimorphic pattern of growth, males growing larger than females. We examined the effects of E₂ and DHT on the GH/IGF-I axis and on VTG production in the tilapia. Sexually mature tilapia were injected with 5 μg g body weight of E₂ (males) or DHT (females) every 5 days for a total of 3 injections. Female tilapia had significantly higher plasma GH levels than males. However, plasma and liver mRNA levels of IGF-I were significantly lower in females than in males, whereas VTG levels in both the plasma and liver mRNA were significantly higher in females than in males. Although significant amounts of VTG were detected in control males (8 ± 0.3 μg ml), the levels in control females (3000 ± 500 μg ml) were about 400 times higher than in males. Males treated with E₂ exhibited a female-like GH/IGF-I profile. That is, they had significantly elevated levels of plasma GH with lower plasma IGF-I and liver IGF-I mRNA levels. Estradiol treatment significantly elevated both plasma and liver mRNA VTG levels. Dihydrotestosterone treatment in females induced a male-like GH/IGF-I profile: plasma GH levels were significantly reduced, whereas plasma and liver IGF-I mRNA levels were significantly elevated. Both plasma and liver mRNA levels of VTG were not altered by DHT treatment. Pituitary GH mRNA levels were similar in all treatment groups. These results clearly indicate that estrogens and androgens feminize and masculinize the GH/IGF-I axis, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

A radioimmunoassay for N-terminal peptide of chum salmon proopiocortin

A highly specific radioimmunoassay was developed for N-terminal peptide of salmonid proopiocortin using a guinea pig antiserum to the chum salmon peptide (sNPP 1). Since sNPP I has no tyrosine residue nor free N-terminal amino group, a mixture of minor components of sNPP 1, which have extensions of H-Val-LysGly- and H-Lys-Gly- at the N-terminus, were iodinated by the lactoperoxidase method after incorporation of 3-(phydroxyphenyl)-propionate to the terminal amino groups. Plasma and pituitary extracts of several salmonid species showed parallel displacement to the standard hormone. Samples from carp, goldfish, tilapia, and eel, as well as the plasma of hypophysectomized rainbow trout, showed no crossreactivity. Proopiocortin-related hormones isolated from the chum salmon pituitary, including melanotropins, endorphins, corticotropin-like intermediate lobe peptides, and gonadotropin and prolactin showed negligible cross-reactivity. NPP contents in the pars intermedia of rainbow trout and chum salmon were 10 to 15 times greater than those in the pars distalis. Plasma levels of NPP in the mature chum salmon caught in the bay were about 50ng/ml. Plasma NPP levels in the mature chum salmon of both sexes decreased after transfer from seawater to fresh water. Plasma cortisol showed a concomitant change with NPP, thus supporting previous findings that NPP modulates corticotropin action on the trout interrenal.     

Some dichlorvos induced plant enzymes and their possible influence on field control of cotton aphid (Homoptera: Aphididae)

Summary

The potential for increased production of the detoxifying enzymes esterase and transferase in cucumber, eggplant, and okra by dichlorvos, and the possible effect of plant insecticide pretreatment on control of cotton aphid, Aphis gossypii, were investigated in a vinyl house. Among the three crops, okra had the highest potential to produce higher amounts of these enzymes, followed by cucumber and eggplant. However, induction of cytochrome P-450 monooxygenase, as measured by the amount of dieldrin produced by aldrin epoxidation, could be detected in okra only at a dichlorvos spray concentration of 500 ppm. These plant induced enzymes linking possibly with other unknown plant factors, generally contributed to 22%, 25%, and 60% reductions in cotton aphid mortality respectively on cucumber, eggplant, and okra. The results suggest among others that cotton aphid chemical control failures may not always be due to the direct effect of insecticide resistance and/or poor control strategies, but a probable consequence of a complex interplay of at least two contributing factors drawn from the viewpoints of both aphid-insecticide and plant-insecticide interactions.