Visfatin: a protein secreted by visceral fat that mimics the effects of insulin

Fat tissue produces a variety of secreted proteins (adipocytokines) with important roles in metabolism. We isolated a newly identified adipocytokine, visfatin, that is highly enriched in the visceral fat of both humans and mice and whose expression level in plasma increases during the development of obesity. Visfatin corresponds to a protein identified previously as pre-B cell colony-enhancing factor (PBEF), a 52-kilodalton cytokine expressed in lymphocytes. Visfatin exerted insulin-mimetic effects in cultured cells and lowered plasma glucose levels in mice. Mice heterozygous for a targeted mutation in the visfatin gene had modestly higher levels of plasma glucose relative to wild-type littermates. Surprisingly, visfatin binds to and activates the insulin receptor. Further study of visfatin's physiological role may lead to new insights into glucose homeostasis and/or new therapies for metabolic disorders such as diabetes.     

KISS1 Gene Expression in the Developing Brain of Female Pigs in Pre- and Peripubertal Periods

Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents, ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1 gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4% paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs.     

First report of triploidy in Ailanthus altissima,an invasive tree species

Ailanthus altissima is a woody plant that has become invasively naturalized in many countries. Using nuclear SSR markers, we studied specimens of this species collected throughout Japan and found an individual (labeled Aa-1) that was not diploid. We examined pollen morphology and ploidy level of Aa-1 by optical microscopy and flow cytometry (FCM), respectively. Some pollen grains were morphologically abnormal and much larger than normal. FCM analysis demonstrated that Aa-1 was triploid. Formation of abnormal pollen indicates that Aa-1 may well have reduced fertility compared to normal diploids. If this were the case, vegetative progeny Aa-1 could be used as ornamentals without attendant risks of future naturalization.     

Ovicidal activity of juvenile hormone mimics in the bean bug,Riptortus pedestris

Insect juvenile hormone (JH) mimics (JHMs) are known to have ovicidal effects if applied to adult females or eggs. Here, we examined the effects of exogenous JHMs on embryonic development of the bean bug, Riptortus pedestris. The expression profiles of JH early response genes and JH biosynthetic enzymes indicated that JH titer was low for the first 3 days of the egg stage and increased thereafter. Application of JH III skipped bisepoxide (JHSB₃) or JHM on Day 0 eggs when JH titer was low caused reduced hatchability, and the embryos mainly arrested in mid- or late embryonic stage. Application of JHMs on Day 5 eggs also resulted in an arrest, but this was less effective compared with Day 0 treatment. Interestingly, ovicidal activity of synthetic JHMs was much lower than that of JHSB₃. This study will contribute to developing novel insecticides that are selective among insect species.     

An application of the alkaline extraction – glucoamylase hydrolysis method to analyze starch and sugar contents of bamboo

The alkaline extraction – glucoamylase hydrolysis (AG) method, which extracts sugars and starch by using sodium hydroxide and hydrolyzes starch by using glucoamylase and α-amylase, was compared with the established ethanol extraction – perchloric acid hydrolysis (EPA) method to analyze the sugar and starch contents of moso bamboo (Phyllostachys pubescens Mazel). The results suggested that the two methods had comparable abilities to extract free sugars from moso bamboo. However, the AG method analyzed starch in moso bamboo more accurately than the EPA method under the proper conditions. When we take into account the better time performance of the AG method versus the EPA method, we can conclude that the AG method is superior to EPA for analyzing the sugar and starch contents of moso bamboo.     

Role of metal proteinases in the fruit-body formation ofHypsizygus marmoreus

We investigated the possible role of metal proteinase on the fruit-body formation ofHypsizygus marmoreus. The addition of a specific metal proteinase inhibitor, phosphoramidon, to the culture medium (10g/ml) completely inhibited fruit-body formation. Metal proteinase activity in both the medium and the mycelia of this fungus increased markedly during vegetative mycelial growth, and activity was maximal 25 days after inoculation. When phosphoramidon was added to the culture medium during vegetative mycelial growth, the metal proteinase activity in the mycelium decreased to 56% of the control (without inhibitor) level. Isoelectric focusing analysis showed that two kinds of metal proteinases with a pl of 7.7 and 8.4, respectively, were obtained from 29-day-old mycelia. Uptake of phosphoramidon into the mycelia was confirmed as the result of inhibition of thermolysin activity by the mycelial extracts. The degree of inhibitor uptake into mycelia was about 2.0% and was independent of the initial concentration of the inhibitor administered. The addition of peptone and amino acids to medium treated with phosphoramidon resulted in fruit-body dry weight yields that were about 50% that of the control.     

Interspecific variation of photosynthesis and leaf characteristics in canopy trees of five species of Dipterocarpaceae in a tropical rain forest

Photosynthetic rate, nitrogen concentration and morphological properties of canopy leaves were studied in 18 trees, comprising five dipterocarp species, in a tropical rain forest in Sarawak, Malaysia. Photosynthetic rate at light saturation (Pmax) differed significantly across species, varying from 7 to 18 micro mol m(-2) s(-1). Leaf nitrogen concentration and morphological properties, such as leaf blade and palisade layer thickness, leaf mass per area (LMA) and surface area of mesophyll cells per unit leaf area (Ames/A), also varied significantly across species. Among the relationships with leaf characteristics, Pmax had the strongest correlation with leaf mesophyll parameters, such as palisade cell layer thickness (r2 = 0.76, P < 0.001) and Ames/A (r2 = 0.73, P < 0.001). Leaf nitrogen concentration and Pmax per unit area also had a significant but weaker correlation (r2 = 0.46, P < 0.01), whereas Pmax had no correlation, or only weakly significant correlations, with leaf blade thickness and LMA. Shorea beccariana Burck, which had the highest P(max) of the species studied, also had the thickest palisade layer, with up to five or more layers. We conclude that interspecific variation in photosynthetic capacity in tropical rain forest canopies is influenced more by leaf mesophyll structure than by leaf thickness, LMA or leaf nitrogen concentration.     

Determination of acetamiprid,imidacloprid, and nitenpyram residues in vegetables and fruits by high-performance liquid chromatography with diode-array detection

Determination of 3 neonicotinoid insecticides, nitenpyram, imidacloprid, and acetamiprid, was studied. Vegetables and fruits were extracted with acetonitrile. The crude extract was passed through a weak anion-exchange cartridge (PSA). The effluent was subjected to silica gel cartridge. Imidacloprid and acetamiprid were eluted with 10 mL of 4:6 (v/v) acetone/hexane, followed by nitenpyram with acetone (20 mL). Pesticides were determined by HPLC with a C-18 column and diode-array detection system. Imidacloprid and acetamiprid were recovered at about 90% at the spike levels with 0.2 and 2 mg/kg in cucumber, potato, tomato, eggplant, Japanese radish, and grape. Nitenpyram was recovered at 64-80%. Relative standard deviations were less than 10% throughout all the recovery tests. In the residue analysis, agriculturally incurred pesticides at 0.08-0.14 mg/kg were designated with UV spectra compared with respective reference standards.     

Digital Microscopy: A Useful Technique for Measuring Root Elongation in Solution

Decreased root elongation and rupture of outer cells, major effects of soluble aluminum (Al), may be studied using digital microscopy with little interference by the experimental technique. Single roots of 3-d-old mungbean ( Vigna radiata L.) or soybean ( Glycine max (L.) Merr.) seedlings were marked with activated charcoal particles and grown for ca. 2 h in 500 mL 1 mM CaCl₂ solution at pH 6, followed by the imposition of an Al treatment. A digital image at 25-time magnification was recorded every 5 min for up to 7 h. Examination of the digital images showed that Al exerted its rhizotoxic effects rapidly (ca. 20–50 min) by reducing cell expansion in the elongation zone. Rupture of epidermal and outer cortical cells occurred later (after≥4 h) and closer to the root tip. Digital microscopy has a number of inherent benefits and problems, but is overall a valuable technique that may find wide use in studies on root growth.     

High-fat diet enhances the accumulation of hexachlorobenzene (HCB) by pregnant rats during continuous exposure to HCB

To investigate the influence of a high-fat diet on HCB distribution and accumulation, pregnant rats in study 1 were fed a high-fat or control diet containing HCB, and, in study 2, pregnant rats were given a single HCB dose by intragastric gavage and HCB-free high-fat or control diet. In study 1, the high-fat diet group had higher HCB concentrations in fat tissues and liver than did the controls. In study 2, although the total amounts of HCB in the fat tissue and liver were greater in the high-fat diet group than in the controls, no significant differences in HCB concentration were observed between the two groups. The high-fat diet group also showed more fecal excretion of HCB. Therefore, HCB accumulation in rats fed a high-fat diet was enhanced more by continuous exposure to HCB than by administration of a single dose.