Fruiting and flushing phenology in Asian tropical and temperate forests: implications for primate ecology

In order to understand the ecological adaptations of primates to survive in temperate forests, we need to know the general patterns of plant phenology in temperate and tropical forests. Comparative analyses have been employed to investigate general trends in the seasonality and abundance of fruit and young leaves in tropical and temperate forests. Previous studies have shown that (1) fruit fall biomass in temperate forest is lower than in tropical forest, (2) non-fleshy species, in particular acorns, comprise the majority of the fruit biomass in temperate forest, (3) the duration of the fruiting season is shorter in temperate forest, and (4) the fruiting peak occurs in autumn in most temperate forests. Through our comparative analyses of the fruiting and flushing phenology between Asian temperate and tropical forests, we revealed that (1) fruiting is more annually periodic (the pattern in one year is similar to that seen in the next year) in temperate forest in terms of the number of fruiting species or trees, (2) there is no consistent difference in interannual variations in fruiting between temperate and tropical forests, although some oak-dominated temperate forests exhibit extremely large interannual variations in fruiting, (3) the timing of the flushing peak is predictable (in spring and early summer), and (4) the duration of the flushing season is shorter. The flushing season in temperate forests (17–28 % of that in tropical forests) was quite limited, even compared to the fruiting season (68 %). These results imply that temperate primates need to survive a long period of scarcity of young leaves and fruits, but the timing is predictable. Therefore, a dependence on low-quality foods, such as mature leaves, buds, bark, and lichens, would be indispensable for temperate primates. Due to the high predictability of the timing of fruiting and flushing in temperate forests, fat accumulation during the fruit-abundant period and fat metabolization during the subsequent fruit-scarce period can be an effective strategy to survive the lean period (winter).     

Isoflavonoid Constituents of Soybeans and Isolation of a New Acetyl Daidzin

The flavonoid constituents of defatted soybeans were studied. Two kinds of new natural isoflavones and four kinds of isoflavones were isolated by rechromatography on silica gel and Sephadex LH–20 columns of ethyl acetate extracts.

One of the new isoflavones was identified as 6″-O-acetyl daidzin, C₂₃H₂₂O₁₀, by UV, IR, PMR and CMR, and the four kinds of isoflavones were also identified as daidzein, daidzin, genistein and genistin.

High performance liquid chromatography of the ethyl acetate and acetone extracts were carried out, and six main peaks corresponding to the six isoflavones were recognized.

Glycitein and glycitein-7-O-glucoside were not detected in the soybeans.     

Studies on the Sulfite Reducing System of Algae

Sulfite reductase using reduced methyl viologen as an electron donor was purified about 94-fold from a red alga, Porphyra yezoensis. The enzyme was ultracentrifugically homogenous and could reduce sulfite to sulfide quantitatively with an uptake of six electrons. The enzyme had a pH optimum in the vicinity of 7.5. The Km for sulfite was determined to be 6.5×l0^?4m. The purified preparation of the algal reductase showed its absorption maximum at 385 mμ and slight shoulders at 408, 456, 485, 600 and 664 mμ in addition to an intense peak at 278 mμ. Metal analysis of the purified enzyme suggested the presence of iron and copper in the molecule. NADPH, NADH or the reduced form of spinach ferredoxin could not be a direct electron donor for the purified algal sulfite reductase.     

Ferredoxin-sulfite Reductase from Spinach

Ferredoxin-sulfite reductase (Fd-SiR) [hydrogen-sulfide: ferredoxin oxidoreductase, EC 1.8.7.1] from spinach leaves has been purified to homogeneity by a new procedure. Subunit analysis by sodium dodecyl sulfate gel electrophoresis yielded a single protein band with a molecular weight of 71,000. Gel electrophoresis in non-denaturing media at different acrylamide concentrations gave a molecular weight of 270,000, suggesting that the native enzyme was composed of four identical subunits. In the presence of 0.2 m sodium chloride, however, gel filtration produced a value of 136,000, indicating the presence of dimer in this ionic environment. A plot of substrate (sulfite) concentration versus enzymatic (Fd-SiR) activity yielded a sigmoidal curve, giving a Hill coefficient (n?) of 2.1. Purified Fd-SiR, in the oxidized form, had absorption maxima at 279, 385, 588 and 714nm. Thus the enzyme has the property of a siroheme-containing protein.     

Ferredoxin-dependent Sulfite Reductase from Spinach Leaves

The intermediate of the aromatization of 4-oxocyclohexanecar-boxylic acid (OHA) to 4-hydroxybenzoic acid (HA) by Coryne-bacterium cyclohexanicum was identified as (+)-4-oxocyclohex-2-enecarboxylic acid (O2A) using a combined system of gas-liquid chromatography (GLC) and a mass spectrometer and polarimeter.     

Seasonal variations in the activity budget of Japanese macaques in the coniferous forest of Yakushima: effects of food and temperature

Seasonal variations in the activity budget of Japanese macaques in the coniferous forest of Yakushima were studied over the course of 1 year. On an annual basis, they spent 38% of the daytime feeding, 16% traveling, 14% in social interactions, and 32% engaged in resting. The effects of temperature and food-related factors (i.e., food distribution, feeding speed, and food abundance) on the seasonal variations of activity budget were examined by stepwise multiple regression analysis. When the temperature was low, the macaques decreased traveling and feeding time, in accordance with the prediction that endothermal animals save energy under severe thermoregulatory cost. When the feeding speed of available foods was slow, they spent more time feeding. When high-quality foods were abundant, they decreased feeding time. These macaques did not respond to fluctuations in food distribution. The present results indicate the importance of temperature, in addition to food-related factors, as a determinant of activity budgets.     

Mass mortality of Japanese macaques in a western coastal forest of Yakushima

The mass mortality of wild Japanese macaques (Macaca fuscata Blyth) was observed in a warm temperate forest of Yakushima, southern Japan. Demographic changes of eight troops between August 1998 and August 1999 were studied and 56% of macaques disappeared from the five intensively studied troops. Mortality varied among troops: two troops became extinct, while another troop did not decrease in size. The rate of mortality of the other troops was between 33 and 80%. The variation in mortality among the troops was either the outcome of local concentrations of mortality or of intertroop competition. The rate of mortality decreased with increasing distance from the two extinct troops and with increasing troop size; these two factors could not be separated statistically. The direct cause of death was diagnosed as pneumonia for four out of five fresh carcasses. The fleshy fruit production in autumn 1998 was the lowest in 14years, and macaques had relied on leaves earlier than in usual years. It was exceptionally hot and dry in the summer of 1998. The exceptionally poor fruit production and hot summer of this year, with the resulting shortage of high-quality foods, was consistent with the scenario that mass mortality was due to the poor nutritional conditions. However, the possibility that epidemics caused the mass mortality cannot be ruled out. Our findings proved that primates in a seemingly stable habitat experience fluctuations in demographic parameters under natural conditions.     

Molecular cloning and characterization of a cDNA encoding ent-cassa-12,15-diene synthase, a putative diterpenoid phytoalexin biosynthetic enzyme, from suspension-cultured rice cells treated with a chitin elicitor

We have isolated and characterized a cDNA encoding a novel diterpene cyclase, OsDTC1, from suspension-cultured rice cells treated with a chitin elicitor. OsDTC1 functions as ent-cassa-12,15-diene synthase, which is considered to play a key role in the biosynthesis of (-)-phytocassanes recently isolated as rice diterpenoid phytoalexins. The expression of OsDTC1 mRNA was also confirmed in ultraviolet (UV)-irradiated rice leaves. In addition, we identified ent-cassa-12,15-diene, a putative diterpene hydrocarbon precursor of (-)-phytocassanes, as an endogenous compound in the chitin-elicited suspension-cultured rice cells and the UV-irradiated rice leaves. The OsDTC1 cDNA isolated here will be a useful tool to investigate the regulatory mechanisms of the biosynthesis of (-)-phytocassanes in rice.