Modelling and analyzing density-dependent population processes: Comparison between wild and laboratory strains of the bean weevil,Callosobruchus chinensis (L.)

Three models were constructed for analyzing the population characteristics ofC. chinensis on stored beans; model A describing the whole reproductive process with a single equation, model B describing the three age-specific processes (oviposition, egg survival and larval survival) with separate equations, and model C which describes all these processes not for the whole habitat but for the individual beans comprizing it. The logit equation was employed here as a common basis to describe the density-response relationship involved. All three models showed very good fit to the experimental data obtained for both laboratory and wild strains of the weevil. The parameter values characterizing the population dynamics were, however, widely different between the two strains; the laboratory one which had been reared for some 500 generations showed significantly higher reproductive capacity, less sensitive and gentler response to crowding in both adult and egg stages, and more uniform egg distribution among individual beans, as compared with the wild strain newly introduced. Sensitivity analyses using these models suggested that these changes in population characteristics have been attained by the process of domestication or adaptation to stable laboratory conditions through a long period of time. This process seemed in effect to have optimized the population's performances in the laboratory environment. Evolutionary significance of such optimization was discussed with reference to the selection pressure which may have acted upon individuals.     

Development and application of photoautotrophic micropropagation plant system

Research has revealed that most chlorophyllous explants/plants in vitro have the ability to grow photoautotrophically (without sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is not due to poor photosynthetic ability, but to the low CO₂ concentration in the air-tight culture vessel during the photoperiod. Moreover, numerous studies have been conducted on improving the in vitro environment and investigating its effects on growth and development of cultures/plantlets on nearly 50 species since the concept of photoautotrophic micropropagation was developed more than two decades ago. These studies indicate that the photoautotrophic growth in vitro of many plant species can be significantly promoted by increasing the CO₂ concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous or porous supporting material with high air porosity instead of gelling agents such as agar. This paper reviews the development and characteristics of photoautotrophic micropropagation systems and the effects of environmental conditions on the growth and development of the plantlets. The commercial applications and the perspective of photoautotrophic micropropagation systems are discussed.     

Tumour necrosis factor and the lysosomal enzymes of macrophages or macrophage-like cell line

Summary The relationship between tumour necrosis factor (TNF) and macrophages or macrophage-like cell line, especially the lysosomal enzymes was investigated. The serum lysosomal enzymes and LDH activities were increased in proportion to the TNF production even in different strains of mice. Lysosomal enzymes and TNF activity were released into the supernatant of the culture medium of macrophage-enriched peritoneal exudate cells (PEC) or spleen cells derived from Propionibacterium acnes-primed mice after addition of lipopolysaccharide (LPS). After passage through a Sephadex G-10 column, TNF activity could not be detected in the supernatant of these spleen cells after addition of LPS. Also TNF activity could not be detected in the supernatant following destruction of PEC. These results suggest that TNF producibility is strongly related to the degree of activation of macrophages, especially the lysosomal enzymes. The murine macrophage-like cell line, J 774, also released TNF activity and lysosomal enzymes after addition of LPS.     

Alkali Protease and Alcohol Dehydrogenase Immobilized to Weakly Basic Anion Exchange Resins Using 2-Car-boxymethylamino-4,6-dichloro-s-triazine

Alkali protease partially purified from a strain of Bacillus subtilis and yeast alcohol dehydrogenase were immobilized to weakly basic anion exchange resins using a bifunctional reagent, 2-carboxymethyIamino-4,6-dichloro-s-triazine.

Properties of these immobilized enzymes were studied both in batchwise operation and in packed bed reactor systems.     

An Interatomic Potential Model for H2O: Applications to Water and Ice Polymorphs

Abstract

A new interatomic potential model for H₂O which consists of 2-body central (O-H, O-O and H-H) and 3-body teams and does not contain artificial constraints on the motions of oxygen and hydrogen atoms is proposed. The interatomic potential function parameters were determined empirically so as to reproduce the fundamental and essential features of water and ice Ih using molecular dynamics (MD) methods.

We carried out the MD simulations of water, and find the Ice Ih, Ice II and Ice IX using this potential model, in structures and physical properties are in agreement with the experimental results except for the compressibilities of both water and ice Ih. We expect that, by refining this model, we can apply this model to problems involving the reaction of water molecules with other components.     

Challenges of reducing excess nitrogen in Japanese agroecosystems

Fertilizer N use in Japan has decreased by about 30% from 1960 to 2000, while keeping a little increase in cereal yields. This has resulted in a significant increase in apparent nitrogen use efficiency, in particular for rice. On the other hand, national N load on the environment associated with the production and consumption of domestic and imported agricultural products has almost tripled during this period, mainly due to the dramatic increase of imports of food and feedstuffs. The environmental problems, including water and air pollution, caused by the excessive loads of N are serious public concerns and there is an urgent need to minimize N losses from agricultural production. In order to meet the necessity for reducing the environmental impacts by excess N, political and technological measures have been taken at regional and country levels. In recent years, the Japanese government has embarked on a series of policies to encourage transition to an environmentally conscious agriculture. Promoting proper material circulation with reducing fertilizer impact and utilizing biomass and livestock wastes is emphasized in these policies. The effectiveness of environmental assessment and planning for reducing regional and national N load has been discussed. Implementation of environmentally friendly technologies and management, both conventional and innovational, have been developed and adopted in Japanese agriculture. The effectiveness of conventional technologies in reducing environmental reactive N has been re-evaluated. Innovative technologies, such as use of controlled availability fertilizers and livestock wastes compost pellets, are being investigated and extended. A comprehensive approach that applies political and technological measures with closer cooperation is necessary to control reactive N in the environment.     

A new species of the genus Laboulbenia (Laboulbeniales) on Ophionea indica (Coleoptera, Carabidae, Odacanthini) from Taiwan

Laboulbenia ophioneae is described as a new species with illustrations. It is closely related to Laboulbenia celestialis and Laboulbenia asiatica because of some similarities in the morphology of appendages and perithecia. The present species from the latter two species can be distinguished by the shorter, inflated perithecia, the shorter receptacles, and the appendages consisting of more or less darkly colored, broader branches. This new species was found on elytra of Ophionea indica from Taiwan, which has been also known as a host of Laboulbenia polymorpha. A mature thallus noticed by Terada (2004) on the slide 673b (M. Ishikawa collection) and a young thallus illustrated by Sugiyama (1978, fig. 1-G as L. polymorpha) on 673d (M. Ishikawa collection) are both identified as L. ophioneae.     

2-Nitropropane Dioxygenase from Hansenula mrakii: Re-characterization of the Enzyme and Oxidation of Anionic Nitroalkanes

2-Nitropropane dioxygenase, purified to homogeneity by an improved method from a yeast, Hansenula mrakii, has a molecular weight of 42,000, and consists of a single polypeptide. The enzyme contains 1 mol of FAD per mol of enzyme. The iron protein associated with previous preparations was removed by the present purification procedures. The enzyme catalyzes the oxygenative denitrification of anionic nitroalkanes much more effectively than that of the neutral ones with the optimum pH of 6.5. The Michaelis constants for the anionic substrates are as follows: 2-nitropropane, 1.61 mM; 1-nitropropane, 3.23 mM; nitroethane, 3.13 mM, and 3-nitro-2-butanol, 0.59 mM.     

Accumulation of major histocompatibility complex class II+CD11c− non‐lymphoid cells in the spleen during infection with Plasmodium yoelii is lymphocyte‐dependent

The spleen is the main organ for immune defense during infection with Plasmodium parasites and splenomegaly is one of the major symptoms of such infections. Using a rodent model of Plasmodium yoelii infection, MHC class II⁺CD11c^? non‐T, non‐B cells in the spleen were characterized. Although the proportion of conventional dendritic cells was reduced, that of MHC II⁺CD11c^? non‐T, non‐B cells increased during the course of infection. The increase in this subpopulation was dependent on the presence of lymphocytes. Experiments using Rag‐2^?/? mice with adoptively transferred normal spleen cells indicated that these cells were non‐lymphoid cells; however, their accumulation in the spleen during infection with P. yoelii depended on lymphocytes. Functionally, these MHC II⁺CD11c^? non‐T, non‐B cells were able to produce the proinflammatory cytokines alpha tumor necrosis factor and interleukin‐6 in response to infected red blood cells, but had only a limited ability to activate antigen‐specific CD4⁺ T cells. This study revealed a novel interaction between MHC II⁺CD11c^? non‐lymphoid cells and lymphoid cells in the accumulations of these non‐lymphoid cells in the spleen during infection with P. yoelii.