Reproductive biology of the female Japanese mantis shrimp Oratosquilla oratoria (Stomatopoda) in relation to changes in the seasonal pattern of larval occurrence in Tokyo Bay, Japan

ABSTRACT:   The reproductive traits and the monthly larval abundance of the mantis shrimp Oratosquilla oratoria were investigated in Tokyo Bay, Japan, in 2002. The goal of the study was to elucidate the cause of changes in the monthly pattern of larval abundance from the 1980s to the 1990s as these changes relate to variation in the stock size of the adult shrimp. Oogenesis was divided into 10 stages by histological observation. The developmental stage of oocytes in an individual's ovary was synchronous, suggesting that almost all the oocytes in an ovary are spawned at the same time. The size at first maturity was estimated to be 7 ≤ body length ( BL ) < 8 cm. Fecundity was expressed as a function of BL , ranging from 19 300 eggs for 8 cm BL to 92 100 eggs for 14 cm BL . Small female shrimps (<10 cm BL ) spawned around August. Most large female shrimps (≥10 cm BL ) spawned around May, and some large female shrimps also spawned until September. Although most large female shrimps spawned in spring, the larval abundance was low before July and high from August onwards. The results suggest that a substantial decrease in the stock size of large individuals causes the low larval abundance before July.     

Purification and properties of pyrethroid carboxyesterase in rat liver microsome

Pyrethroid carboxyesterase which hydrolyzes the esters of chrysanthemumic acid was purified from rat liver microsome by cholic acid solubilization, ammonium sulfate fractionation, heat treatment, and DEAE-Sephadex A-50 column chromatography. The 45-fold purified enzyme (38% yield) is likely to consist of single protein, as evidenced by polyacrylamide gel disc electrophoresis and Sephadex G-100 column chromatography, and had a molecular weight of approximately 74,000 and a K_m of 0.21 mM. It is susceptible to inhibition by organophosphates and carbamate insecticides and insensitive to pCMB, mercuric ion, and cupric ion. It is capable of hydrolyzing trans isomers of synthetic pyrethroids much more rapidly (five to ten times) than the cis counterparts. The purified pyrethroid carboxyesterase is apparently identical in nature with malathion carboxyesterase and with p-nitrophenyl acetate carboxyesterase.     

Avian predation on wild and cultured sea urchin <Emphasis Type="Italic">Strongylocentrotus intermedius</Emphasis> in a rocky shore habitat

ABSTRACT:   The present study reports the annual variation in consumption of the sea urchin Strongylocentrotus intermedius by avian predators on a rocky shore where the culture of sea urchins has been conducted. Carrion crow and a few gull species were the most abundant avian predators and consumed a large number of sea urchins. Crows consumed mostly natural sea urchins, approximately 36 kg ww/ha per year on the intertidal rocky bench, but the gull species consumed mostly cultured sea urchins, approximately 100 kg ww/ha per year in the culture area. The seasonal variation in the amount of sea urchins consumed by crows was higher than that by the gull species, presumably because of the difference in foraging behavior in association with the seasonal tidal cycle. The natural sea urchins consumed are an allochthonous input from the subtidal to the intertidal habitat, and thus, crow predation may not affect the natural and the cultured populations of the sea urchin. The gull species consumed much of the cultured sea urchin, and thus, may be regarded as an effective predator causing damage to sea urchin culture. The results suggest that further studies are needed to determine why the gull species selectively feed on cultured sea urchins.     

Utilization of Sake lees as Broiler Feedstuff and its Effects on Growth Performance and Intestinal Immunity

Increasing food loss and waste (FLW) is a global problem, and efforts are being made to use waste food as potential livestock feed material. The amount of self-supplied feed is lower in Japan than in other countries, and the government recommends FLW use for animal feed. Sake (Japanese rice wine) is a traditional alcoholic beverage. During the sake manufacturing process, large amounts of squeezed solids or “lees” (sake lees) are generated. Sake lees are nutritious and functional, but are prone to spoilage. In this study, we investigated whether sake lees should be mixed with animal feed immediately or after drying. To assess the usefulness of sake lees as a poultry feed ingredient and determine the effect of sake lees on intestinal immunity, we performed a feeding trial with three treatments: a raw sake lees (RSL) diet, dried sake lees (DSL) diet, and control diet. Three-week-old broilers were fed these diets (n=8 per group) for two weeks. We then calculated feed efficiency and performed RT-qPCR to assess the effects of diet on intestinal immunity. The growth performance in the RSL diet group was equivalent to that in the control diet group. The DSL diet became difficult for broilers to eat, resulting in decreased growth performance. In the ileum of RSL-diet broilers, the mRNA expression levels of TGF-β1 and avian β-defensin (AvBD)12 were significantly increased compared to those of control diet broilers (p<0.05), and a significant correlation was observed between the two genes (p<0.05). Our results indicated that sake lees should not be dried and should be mixed immediately with feed, and this sake lees when fed to chicken activates the intestinal immunity. However, sake lees have a lower fat content than corn, and it is thus important to combine sake lees with high-energy feed.     

A new method for measuring microbial biomass nitrogen in soils: Direct extraction after toluene treatment

Abstract

Phenolic compounds occurring naturally are reducing agents which react with hydrous Fe oxide and Mn oxides (Lehmann et al. 1987). Diphenols such as hydroquinone, resorcinol, and catechol were oxidatively darkened by the presence of hydrous Fe oxide though the degree of darkening was much less pronounced than that by Mn oxides (Shindo and Huang 1984). Okazaki et al. (1976) suggested that polyphenols are one of the materials responsible for the dissolution of Mn in a paddy soil under reducing conditions.     

Evaluation of relationship between dispersibility of soils and charge characteristics using a modified ion adsorption method; An example of soils from Wakayama Prefecture,Japan

The relationship between the charge characteristics and the dispersibility of soils from reclaimed land (highly dispersive) and adjacent forest area (physically stable) was investigated.

To evaluate the amount of soil charges quantitatively, the measurement based on cation and anion adsorption (ion adsorption method) was attempted in two ways, where special attention was paid to the solution concentration. In the conventional ion adsorption method, the treatments with concentrated solutions (1 mol L^-1) were included in the process. In the modified method, soils were treated with dilute solutions (5 mmol L^-1), in taking account of the soil solution concentration in humid temperate regions. The amount of charges derived from the modified method was smaller than that from the conventional one, especially in the high pH zone. In a preliminary experiment, the extraction of polyvalent cations from soils was found to be significantly affected by the salt concentration. Thus, the use of solutions with an excessively high concentration was considered to result in an error in the estimation of the active charges in soils which would contribute to the dispersion behavior in the field.

The applicability of the modified method for analyzing the dispersion behavior of soils was evaluated by relating the dispersibility of silts and clays at different pHs with the charge characteristics determined under the same ionic strength. The dispersion ratio of silts of the reclaimed land reached maximum values at pH 5.5, above which the ratio decreased, whereas the ratio of clays began to increase in the pH range above 6. The dispersion ratio of silts of the forest area increased in the pH range above 6, whereas that of clays remained constant at a low level in all the pH ranges below 7. The changes in the dispersibility of silt plus clay fractions corresponded to total charge characteristics determined by the modified method. Thus, the evaluation of soil charges by the modified ion adsorption method was considered to be effective to predict soil dispersibility under field conditions, indicating that it could replace electrokinetic analyses such as electrophoresis in studies on the dispersion/flocculation behavior of soils.