Lectin-induced enhancement of superoxide anion production by red tide phytoplankton

Chattonella marina, a raphidophycean flagellate, is a highly toxic red tide phytoplankton which causes severe damage to fish farming. Recent studies demonstrated that Chattonella spp. continuously release superoxide anions (O₂ ⁻) while they are living. Heterosigma akashiwo, another raphidophycean flagellate, also produces O₂ ⁻. In the present study, we found that lectins such as concanavalin A (Con A), wheat germ agglutinin (WGA), and castor bean hemagglutinin (CBH) stimulated  C. marina and H. akashiwo to generate enhanced amounts of O₂ ⁻ in a concentration-dependent manner. The lectin-specific sugars potently inhibited the lectin-induced increase of O₂ ⁻ production, suggesting that the effects of lectins are mediated mainly through the interaction of these lectins with carbohydrate moiety present on the flagellate cell surface. In contrast to the potent ability of native Con A (tetravalent), succinylated Con A (divalent) showed only a slight stimulative effect on these flagellates. O₂ ⁻ production was totally inhibited by treatment with proteinase K for 30 min, without affecting the viabilities of flagellates. These results suggest that cell-surface redox enzymes may be involved in O₂ ⁻ production, and such enzymes are responsible for the lectin-stimulation. Received: 21 August 1997 / Accepted: 8 January 1998     

Lifespan and oviposition of the parasitic copepod Pseudomyicola spinosus under rearing conditions

The facultative parasitic copepod Pseudomyicola spinosus (Raffaele & Monticelli) was cultured and mated under laboratory conditions. Twenty virgin females were cultured in isolation and mated. They were cultured individually after mating, and examined for lifespan, number of ovipositions, number of eggs, and other features. The longest lifespan of a female P. spinosus was 2.3 years (849 d). This female laid eggs 106 times after a single mating, and all of the eggs developed. The lifespan and number of ovipositions varied with the individual, but the interval between ovipositions showed less variation (7.0±2.3 d). The number of eggs laid at one oviposition decreased with the increase in the age of the female. The number of eggs at each oviposition was smaller in laboratory females than in wild females, but the oviposition rhythm and the interval between ovipositions seemed to be the same. The sperms seem to survive for quite a while in the seminal receptacle of a female. A male can copulate a multiple of times. The lifespan of P. spinosus in the natural environment should be less than a year, considering the lifespan of the host mussels.     

日本Biwai湖-Yodo河水体系的可持续管理

Biwa湖 Yodo河水系为主要的居民中心及其周围的市政机构提供城市用水和工业用水 .它也提供农业用水，主要在 Biwa湖排水区域 .该水系服务的人口总数约为 1400万人 . 这个水系构成了 Keihanshin工业区的主要部分（按照字面上是指京都、大阪和神户），这是一个以沿大阪海湾－濑户内海的狭长地带发展为特征的一个区域 .Keihanshin的工业产值居日本的第三位，约占国内生产总值的 12.4％ .一个复杂的供水网和废水网支持着高水平的工业和农业活动 .     

Participation of the C-type hemolymph lectin in mineralization of the acorn barnacle Megabalanus rosa

BRA-2, a major C-type lectin in the hemolymph of the acorn barnacle Megabalanus rosa was detected in shell-associated proteins. Immobilized BRA-2 promoted CaCO₃ crystallization as determined by an in vitro pH-drift mineralization assay. In nature, calcification occurs as wound repair in M. rosa after breakage of the shell plate. To observe this phenomenon, we inserted a rubber cube inside the mantle cavity of M. rosa through the basal plate, and kept the organisms in a tank for several weeks. The rubber cube was covered first with brownish-colored material, probably a melanin, and then with CaCO₃ 5 weeks after the insertion. In the CaCO₃-associated proteins, BRA-3, a minor component of M. rosa hemolymph lectins, was present in addition to BRA-2. The presence of both the lectins and their ligands on the hemocyte was also observed. These results suggest that the C-type lectins of the M. rosa hemolymph participate in mineralization as well as defense in these organisms.     

Changes in otolith strontium:calcium ratios in metamorphosing Conger myrisaster leptocephali

Content ratios of strontium (Sr) to calcium (Ca) in the otolith of Conger myriaster metamorphosing leptocephali and elvers increased with increasing increment number from the core to the 110th increment and subsequently decreased. The otolith region from the 110th increment to the edge corresponded to the metamorphic stage. The Sr:Ca ratios in otolith edges of metamorphosing leptocephali were inversely related to metamorphic stage, suggesting that the changes in otolith Sr:Ca ratios were influenced by some physiological factor(s) rather than by environmental factors. Sr concentration in leptocephalus somatic tissues was high and decreased as metamorphosis progressed until the late metamorphic stage when the preanal myomere to total myomere ratio was 0.4. Ca concentration was constant throughout ontogenesis. Body Sr:Ca ratios markedly decreased as metamorphosis progressed. Decrease in somatic Sr concentration and the consequent decrease in body Sr:Ca ratios seemed to be associated with the breakdown of glycosaminoglycan (GAG) in gelatinous matrix, which is the major constituent of soft tissue in leptocephali. Catabolism of GAG may also cause a decrease in otolith Sr:Ca ratios during metamorphosis. In leptocephalus otoliths, Sr:Ca ratios may change in association with the synthesis and breakdown of GAGs during ontogeny. Received: 29 November 1996 / Accepted: 6 January 1997     

The functional organization of resin work in honeybee colonies

Resin is an important building material in the nests of honeybees, but little is known about how it is handled within the nest and how its collection is controlled. We studied the functional organization of resin work to better understand how a colony adaptively controls its intake of resin. Two hypotheses have been proposed for how resin collectors stay informed of the need for additional resin: (1) the unloading difficulty hypothesis (resin need is sensed indirectly by the unloading delay) and (2) the caulking activity hypothesis (resin need is sensed directly while engaged in using resin). A falsifiable prediction of the latter hypothesis, but not of the former, is that resin collectors not only gather resin outside the hive but also regularly handle resin inside the hive (taking it from other bees and using it to caulk crevices). Consistent with this prediction are our findings that in the resin sector of a colony’s economy, unlike in the pollen, nectar, and water sectors, there is no strict division of labor between the collectors and the users of a material. Over the course of a day, bees seen collecting resin were also commonly seen using resin. Moreover, we found that the unloading locations of resin collectors are unlike those of water and nectar collectors, being deep inside the hive (at the sites of resin use) rather than at the hive entrance. This arrangement facilitates the engagement in resin use by resin collectors. We conclude that the caulking activity hypothesis is well-supported, but that the unloading difficulty hypothesis also remains viable, for we found that resin collectors experience variable delays in getting rid of their loads, from less than 15 min to more than an hour, consistent with this hypothesis. The stage is now set for experimental tests of these two hypotheses. Both may be correct, which if true will imply that social insect workers, despite their small brains, can acquire and integrate information from multiple sources to improve their knowledge of conditions within the colony.     

Congener profiles of PCDDs, PCDFs, and dioxin-like PCBs in the breast milk samples in Tokyo, Japan

Exposure to dioxins has raised much public concern recently. We determined the congeners' distribution of polychlorinated-dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in the breast milk samples collected in Tokyo, Japan. Breast milk was taken from 240 mothers, 30 days after delivery in 1999 and 2000 in Tokyo, Japan. The actual concentration and TEQ concentration of PCDDs (14 congeners), PCDFs (15 congeners), and dl-PCBs (12 congeners), and each congener's contribution to the total TEQ level were calculated. Among all the samples, PCDDs accounted for 34.8%, PCDFs accounted for 23.5%, dl-PCBs accounted for 41.7%, which was also similar in the breast milk from the primiparae and secundiparae. The main contributors to the total TEQ with increasing percentages were 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD and 3,3',4,4',5-PCB (#126), and they accounted for more than 65% of the total TEQ. Detailed congener analysis in breast milk samples is effective to understand dioxin sources.     

Effects of dietary habits and CYP1A1 polymorphisms on blood dioxin concentrations in Japanese men

The major source of dioxin impurities in Japan in the past was agrochemical formulations; more recently, it has been exhaust from waste incinerators. To examine the environmental and genetic factors that influence blood dioxin concentration, we investigated the relationship among dioxin concentrations, dietary habits and cytochorome P450 1A1 (CYP1A1) polymorphisms (MspI type and Ile-Val type) in Japanese fishermen and farmers, including also a group of office workers as controls. The mean dioxin concentrations in the fishermen, the farmers and the controls were 161369, 79079 and 100500 pg/g fat, respectively. The elevated dioxin concentration with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and coplanar-PCBs found in the fishermen may be due to the frequent consumption of fish; no such relationship was found both in the farmers and the controls. We found that the concentrations of congeners found as impurities in certain chemicals such as those previously used in agriculture showed no significant differences among the three groups; we consider it unlikely that the farmers would be directly exposed to dioxins from such chemicals. Thus, it is probable that the primary route of dioxin exposure in the Japanese population is through the food chain via fish consumption, regardless of occupation. No meaningful relationship between blood dioxin concentration and CYP1A1 polymorphisms was found in this study, although there was a significant difference between the concentration of total non-ortho-PCBs in genotypes A and B. Further studies on more subjects, including those of genotype C, are needed to confirm the relationship between blood dioxin concentrations and MspI polymorphisms.     

Recycling, landfill consumption, and CO2 emission: analysis by waste input–output model

The emission of waste in an economy, including landfill, is to a large extent determined by its patterns of technology, institutions, and lifestyle. A mathematical model (the waste input–output model) is presented that gives a simple analytical representation of this interdependence. The model was used to evaluate the effects of alternative waste disposal and recycling options on the levels of industrial production, landfill consumption, and the emission of carbon dioxide, and also to analyze the overall dependence on landfill of individual industries. It was found that a systematic combination of the options could be effective in reducing the overall landfill consumption and carbon dioxide emission. Received: November 4, 2000 / Accepted: August 2, 2001