Coordinated accumulation of the chloroplastic and cytosolic pyruvate,Pi dikinases with enhanced expression of CAM in Kalanchoë blossfeldiana

Recent studies reveal that the intracellular localization of pyruvate,Pi dikinase (PPDK, EC 2.7.9.1) in mesophyll cells of malic enzyme (ME)-dependent Crassulacean acid metabolism (CAM) plants varies among species, occurring not only in the chloroplasts but also in the cytosol in some species. The facultative CAM plant Kalanchoë blossfeldiana accumulates PPDK in both compartments of the mesophyll cells. In this study, the patterns of accumulation of the chloroplastic and cytosolic PPDKs were investigated for K. blossfeldiana plants with different CAM activities by immunogold labeling and electron microscopy. Greater CAM activity was found in plants grown under drought conditions with short days than under well-watered conditions with long days, and in lower leaves than in higher leaves. There was a trend that plants and leaves with greater CAM activity show denser labeling for PPDK in both the cytosol and chloroplasts. However, the ratio of the density of PPDK labeling in the cytosol to that in the chloroplasts was almost constant (2.4–3.0). Higher labeling for phosphoenolpyruvate carboxylase (EC 4.1.1.31) in the cytosol was also correlated with higher CAM activity but there was almost no difference in the density of labeling for ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) in the chloroplasts. These results indicate that the increase in accumulation of cytosolic PPDK is closely associated with the increase of chloroplastic PPDK during enhanced CAM expression. This suggests that both PPDKs are involved in CAM function.     

Internal Spatiotemporal Population Dynamics of Infection with Three Wolbachia Strains in the Adzuki Bean Beetle, Callosobruchus chinensis (Coleoptera: Bruchidae)

The adzuki bean beetle, Callosobruchus chinensis, is infected with three distinct lineages of endosymbiotic bacteria belonging to the genus Wolbachia, which were designated wBruCon, wBruOri, and wBruAus. In an attempt to understand the mechanisms underlying the infection with these three organisms, the spatiotemporal infection dynamics of the three Wolbachia strains was investigated in detail by using a quantitative PCR technique. During the development of C. chinensis, the wBruCon, wBruOri, and wBruAus infection levels consistently increased but the growth patterns were different. The levels of infection plateaued at the pupal stage at approximately 3 × 10⁸, 2 × 10⁸, and 5 × 10⁷ wsp copy equivalents per insect for wBruCon, wBruOri, and wBruAus, respectively. At the whole-insect level, the population densities of the three Wolbachia types did not show remarkable differences between adult males and females. At the tissue level, however, the total densities and relative levels of the three Wolbachia types varied significantly when different tissues and organs were compared and when the same tissues derived from males and females were compared. The histological data obtained by in situ hybridization and electron microscopy were concordant with the results of quantitative PCR analyses. Based on the histological data and the peculiar Wolbachia composition commonly found in nurse tissues and oocytes, we suggest that the Wolbachia strains are vertically transmitted to oocytes not directly, but by way of nurse tissue. On the basis of our results, we discuss interactions among the three coinfecting Wolbachia types, reproductive strategies of Wolbachia, and factors involved in the different cytoplasmic incompatibility phenotypes.     

The Waste Input-Output Approach to Materials Flow Analysis

Abstract: A general analytical model of materials flow analysis (MFA) incorporating physical waste input-output is proposed that is fully consistent with the mass balance principle. Exploiting the triangular nature of the matrix of input coefficients, which is obtained by rearranging the ordering of sectors according to degrees of fabrication, the material composition matrix is derived, which gives the material composition of products. A formal mathematical definition of materials (or the objects, the flow of which is to be accounted for by MFA) is also introduced, which excludes the occurrence of double accounting in economy-wide MFAs involving diverse inputs. By using the model, monetary input-output (IO) tables can easily be converted into a physical material flow account (or physical input-output tables [PIOT]) of an arbitrary number of materials, and the material composition of a product can be decomposed into its input origin. The first point represents substantial saving in the otherwise prohibitive cost that is associated with independent compilation of PIOT. The proposed methodology is applied to Japanese IO data for the flow of 11 base metals and their scrap (available as e-supplement on the JIE Web site).     

Recent Physical Encounters Affect Chemically Mediated Retreat-Site Selection in a Gecko

Chemoreception is well documented in a range of animals but the effects of recent behavioural interactions on an animal's response to subsequent chemical information are poorly understood. Using a series of laboratory experiments with a rock‐dwelling gecko (Oedura lesueurii), we examined whether latest social experience affects how animals used chemoreception to mediate microhabitat selection. Males of this species defend retreat‐sites and the outcomes of physical duels are maintained during second physical contests staged up to 1 wk after first contests. Retreat‐site selection experiments showed that past social experience affects the behavioural responses of adult male geckos to chemical cues from conspecific male lizards. When offered a choice between retreat‐sites labelled with chemicals from an unknown male vs. the opponent from a recent contest, geckos that won their previous fight selected retreat‐sites at random. In contrast, under the same conditions, geckos that lost their previous fight significantly preferred retreat‐sites scented with an unknown male conspecific over those scented with the winning opponent. During these experiments males that lost their previous fight were significantly more vigilant, and spent greater time near the retreat‐site of the unknown male, compared with males that won their previous fight. These results support the notion that recent physical social encounters can affect the way that animals respond to chemical information from potential competitors.     

Iron-chlorophyllin-mediated conversion of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2(NHOH)) into its nitroso derivative

Early work from our laboratory has shown that the mutagenicity of heterocyclic amines in Salmonella can be inhibited by hemin and chlorophyllins. We have speculated that the inhibition is a result of complex formation between heterocyclic amines and the pigments, and the speculation has been given a line of experimental evidence. We have now found that ferric-chlorophyllin (Fe-chlorophyllin) can modify the mutagenicity of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2(NHOH)), a metabolically activated form of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The mutagenicity of Trp-P-2(NHOH)) in Salmonella typhimurium TA 98 (without S9) was strongly inhibited by an addition of an equimolar Fe-chlorophyllin in the pre-incubation mixture. Fe-chlorophyllin also inhibited the mutagenicity of 2-hydroxyamino-6-methyldipyrido[1,2-a:3′,2′-d] imidazole (Glu-P-1(NHOH)). A rapid change in the UV spectrum of a mixture of Trp-P-2(NHOH) and Fe-chlorophyllin was observed. Analysis by high performance liquid chromatography showed that Trp-P-2(NHOH) was converted into 3-nitroso-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2(NO)), the mutagenic potency of which is a quarter of that of Trp-P-2(NHOH). Furthermore, the mutagenicity of Trp-P-2(NO), in turn, was inhibited by Fe-chlorophyllin. We conclude that the suppression of the mutagenicity of Trp-P-2(NHOH) is ascribable to the oxidative function of Fe-chlorophyllin, coupled with its ability to form complex formation with the planar surface of the heterocyclic amine molecules.     

Physiological significance of hydrophilic and hydrophobic textile materials during intermittent exercise in humans under the influence of warm ambient temperature with and without wind

The purpose of this present study was to compare the physiological effects of the hydrophilic and hydrophobic properties of the fabrics investigated in exercising and resting subjects at an ambient temperature of 30°C and a relative humidity of 50% with and without wind. Three kinds of clothing ensemble were tested: wool and cotton blend with high moisture regain (A), 100% cotton with intermediate moisture regain (B), 100% polyester clothing with low moisture regain (C). The experiments were performed using seven young adult women as subjects. They comprised six repeated periods of 10-min exercise on a cycle ergometer at an intensity of 40% maximal oxygen uptake followed by 5 min of rest (20 min for the last rest). The experiments comprised two sessions. During session I (first three repetitions of exercise and rest) the subjects were exposed to an indifferent wind velocity and during session II (last three repetitions of exercise and rest) they were exposed to a wind velocity of 1.5 m · s⁻¹. Rectal temperature and skin temperatures at eight sites, pulse rate and clothing microclimate were recorded throughout the whole period. The main findings can be summarized as follows: rectal temperature during session II was kept at a significantly lower level in A than in B and C. Clothing microclimate humidity at the chest was significantly lower in A than in B and C during session II. Skin and clothing microclimate temperatures at the chest were significantly lower in A than in B and C during session II. Pulse rate was significantly higher in C than in A and B during sessions I and II. It was concluded that the hydrophilic properties of the fabrics studied were of physiological significance for reducing heat strain during exercise and rest especially when influenced by wind. Accepted: 3 June 1998     

A dynamic neural network with temporal coding and functional connectivity

A neural network model capable of altering its pattern classifying properties by program input is proposed. Here the “program input” is another source of input besides the pattern input. Unlike most neural network models, this model runs as a deterministic point process of spikes in continuous time; connections among neurons have finite delays, which are set randomly according to a normal distribution. Furthermore, this model utilizes functional connectivity which is dynamic connectivity among neurons peculiar to temporal-coding neural networks with short neuronal decay time constants. Computer simulation of the proposed network has been performed, and the results are considered in light of experimental results shown recently for correlated firings of neurons. Received: 6 December 1996 / Accepted in revised form: 15 September 1997