Evaluating vegetation recovery following large-scale forest fires in Borneo and northeastern China using multi-temporal NOAA/AVHRR images

This study evaluated whether a normalized difference vegetation index (NDVI), derived from 8-km-resolution National Oceanic Atmospheric Administration (NOAA) Pathfinder AVHRR (advanced very high resolution radiometer) land (PAL) data, is appropriate for monitoring recovery following large-scale forest fires. Recovery processes were examined after fires on the island of Borneo and in northeastern China in 1983 and 1987, respectively. Based on pre- and post-fire NDVI differences (NDVId), six damage classes were established. Post-fire changes in land cover were monitored using (1) the average NDVI of all pixels corresponding to each damage class (A-NDVI) and (2) the ratio of a fire-affected A-NDVI to a non-fire-affected A-NDVI (QNDVI). Burn areas located by an NDVId threshold value were similar to reported burn areas. Both A-NDVI and QNDVI values signaled vegetation recovery, but the QNDVI gave much better results. For both the 1983 Borneo and 1987 northeastern China fires, QNDVI values dropped at the time of the fire and increased for about 4 years afterwards, although a 4-year period is obviously less than the time required for biomass recovery. Trends at the two study sites diverged after this period, however. The QNDVI values for multiple fire events in Borneo (in 1983, 1987, 1991, 1997, and 1998) showed that recovery times varied with the size of the burn area, but not with the damage class of the same event, whereas the severe-class QNDVI values for the fire in northeastern China in 1987 were still lower than the control value 10 years after the fire.     

Effects of co‐supply ratios of swimming crab Portunus trituberculatus zoeae and Artemia on survival and growth of East Asian common octopus Octopus sinensis paralarvae under an upwelling culture system

Despite recent advances in culture technology for East Asian common octopus Octopus sinensis paralarvae using upwelling systems, securing suitable feed for the paralarvae is an unresolved issue. The zoea of the swimming crab Portunus trituberculatus is a good candidate for paralarval feed because of the high fecundity of the adult females. To investigate the effects of supplying P. trituberculatus zoeae and their feeding method on paralarvae, we cultured paralarvae with supplying different combination ratios of zoeae and Artemia (10:0, 7:3, 5:5, 3:7 and 0:10), and with or without supplementing rotifers using small‐scale (3‐L) upwelling systems. Paralarval survival rate and growth were improved when zoeae were supplied as the main feed, but reduced when the proportion of Artemia exceeded half the whole preys. Supplementing rotifers did not affect the paralarval survival and growth. Subsequently, paralarvae were cultured by supplying zoeae (partially augmented by Artemia) using three large (1‐kl) upwelling systems to assess their feeding effectiveness in juvenile octopus production. Paralarvae could be cultured at high survival rates of 77.1 ± 5.1% to reach benthic juveniles at 23 days after hatching. In conclusion, supplying P. trituberculatus zoeae augmented with Artemia under an upwelling culture system has great potential for juvenile octopus production.     

Survey of coccidial oocysts and parasite eggs in feces of free-ranging Grus japonensis

Fecal survey of Eimeria oocysts and parasite eggs was conducted for 219 fecal samples of free-ranging Grus japonensis in Kushiro district in Hokkaido in April 2003. Positive rate and mean oocysts (or eggs) per gram in positive samples were 26% (57/219) and 8.8 (0.2-136) in oocysts of Eimeria reichenowi, 18.3% (40/219) and 320 (100-1,000) in trematode eggs, 0.1% (2/219) and 0.2 (0.2-0.3) in eggs of Nematoda A, and 4.1% (9/219) and 0.8 (0.2-3.6) in eggs of Nematoda B, respectively.     

Estrous cycle based on blood progesterone profiles and changes in vulvar appearance of Malayan tapirs (Tapirus indicus)

The progesterone (P(4)) profiles and macroscopic vulvar changes of female Malayan tapirs were investigated in order to understand their fundamental reproductive physiology and to search for visual indicators of estrus. Blood was collected once or twice a week from seven female Malayan tapirs kept at four zoos. Serum or plasma P(4) concentrations were determined by radioimmunoassay. The P(4) concentrations changed cyclically throughout the years, and a total of 56 cycles was confirmed in the seven females. The length of the estrous cycle based on the P(4) profiles was 43.6+/-2.0 days; however, this mean includes great variation in length, from 21 to 84 days. Mucous discharge from the vulva and vulvar swelling were seen when the P(4) concentrations were low before the beginning of a rise in most cases. In conclusion, captive female Malayan tapirs have variations of approximately 1 to 3 months in estrous cycle length, and visual changes in the vulva are helpful in estimating estrus in female Malayan tapirs.     

Effects of heavy metal accumulation in apple orchard soils on microbial biomass and microbial activities

Abstract

The effects of heavy metals (Cu, Pb, and As) accumulated in apple orchard surface soils on the microbial biomass, dehydrogenase activity, and soil respiration were investigated. The largest concentrations of total Cu, Pb, and As found in the soils used were 1,010, 926, and 166 mg kg^?1 soil, respectively. The amounts of microbial biomass C and N, expressed on a soil organic C and soil total N basis, respectively, were each negatively correlated with the amounts of total, 0.1 M HCI-extractable, and 0.1 M CaCl₂-extractable Cu as logarithmic functions, the correlation coefficient being lowest for the 0.1 M CaCl₂extractable Cu. Nevertheless, they were not correlated with the soil pH which was controlling the solubility of Cu in 0.1 M CaCl₂. The dehydrogenase activity expressed per unit of soil organic C was also negatively correlated with the amounts of total, 0.1 M HCI-extractable Cu, and 0.1 M CaCl₂-extractable Cu as logarithmic functions. However, the correlation coefficient was highest for the 0.1 M CaCl₂-extractable Cu. Although the soil respiration per unit of soil total organic C did not show any significant correlations with the total concentrations of heavy metals, it showed negative significant correlations with the amount of 0.1 M HCI-extractable Cu, and to a greater extent, with the amount of 0.1 M CaCl₂-extractable Cu. Both the dehydrogenase activity and respiration per unit of soil total organic C increased significantly with increasing soil pH. These results suggested that in apple orchard soils with heavy metal accumulation the microbial biomass was adversely affected by the slightly soluble Cu, whereas the microbial activities by the readily soluble Cu whose amount depended on the soil pH. The respiration per unit of microbial biomass C showed a positive significant correlation with the logarithmic concentration of total Cu. Furthermore, the contribution of fungi to substrate-induced respiration increased with increasing total Cu content in the soils.     

Solid-phase synthesis of mimosine tetrapeptides and their inhibitory activities on neuraminidase and tyrosinase

Neuraminidase is a rational target for influenza inhibition, and the search for neuraminidase inhibitors has been intensified. Mimosine, a nonprotein amino acid, was for the first time identified as a neuraminidase inhibitor with an IC(50) of 9.8 ± 0.2 μM. It was found that mimosine had slow, time-dependent competitive inhibition against the neuraminidase. Furthermore, a small library of mimosine tetrapeptides (M-A(1)-A(2)-A(3)) was synthesized by solid-phase synthesis and was assayed to evaluate their neuraminidase and tyrosinase inhibitory properties. Most of the tetrapeptides showed better activities than mimosine. Mimosine-FFY was the best compound, and it exhibited 50% neuraminidase inhibition at a low micromolar range of 1.8 ± 0.2 μM, whereas for tyrosinase inhibition, it had an IC(50) of 18.3 ± 0.5 μM. The kinetic studies showed that all of the synthesized peptides inhibited neuraminidase noncompetitively with K(i) values ranging from 1.9 -to 7.2 μM. These results suggest that mimosine could be used as a source of bioactive compounds and may have possibilities in the design of drugs as neuraminidase and tyrosinase inhibitors.     

Inhibitory effects of cucurbitane glycosides and other triterpenoids from the fruit of Momordica grosvenori on epstein-barr virus early antigen induced by tumor promoter 12-O-tetradecanoylphorbol-13-acetate

Two new triterpene benzoates, 5-dehydrokarounidiol dibenzoate (1) and karounidiol dibenzoate (2), and two new triterpene glycosides, 5alpha,6alpha-epoxymogroside IE(1) (8) and 11-oxomogroside A(1) (9), along with 15 known triterpenoids (one triterpene benzoate, 3; three triterpene mono-ols, 4-6; one triterpene aglycon, 7; and 10 triterpene glycosides, 10-19), were isolated from the ethanol extract of the fruit of Momordica grosvenori. The structures of 1, 2, 8, and 9 were determined on the basis of spectroscopic and chemical methods. Among the known triterpene glycosides, mogroside I E(1) (12) was a new naturally occurring compound. Eighteen triterpenoids (2-19) and 11-oxomogrol (20), a hydrolysis product of 9, were evaluated with respect to their inhibitory effects on the induction of Epstein-Barr virus early antigen (EBV-EA) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, which is known to be a primary screening test for antitumor promoters. All of the compounds tested showed potent inhibitory effects on EBV-EA induction (70-100% inhibition at 1 x 10(3) mol ratio/TPA).     

Effect of forest structure on the spatial variation in soil respiration in a Bornean tropical rainforest

This study was undertaken to identify critical and practical factors explaining spatial variations in soil respiration and to estimate stand-scale soil respiration in an aseasonal tropical rainforest on Borneo Island. To this aim, we conducted soil respiration measurements at 25 points in a 40 m × 40 m subplot of a 4 ha study plot between 2002 and 2006, and examined the spatial variation in soil respiration averaged over the 4 years in relation to soil, root, and forest structural factors. In addition, we examined the spatial representativeness of soil respiration measured in the subplot using a specific scaling procedure. Consequently, we found significant positive correlation between the soil respiration and forest structural parameters such as the mean diameter at breast height (DBH), total basal area, and maximum DBH within 6 m of the measurement points. The most important factor was the mean DBH within 6 m of the measurement points, which had a significant linear relationship with soil respiration. Using the derived linear regression and an inventory dataset, we estimated the 4 ha plot-scale soil respiration. The 4 ha plot-scale estimation (6.0 μmol m⁻² s⁻¹) was nearly identical to the subplot-scale measurements (5.7 μmol m⁻² s⁻¹), which were roughly comparable to the nocturnal CO₂ fluxes calculated using the eddy covariance technique. In addition, we discuss characteristics of the stand-scale soil respiration at this site by comparing with those of other forests reported in previous literature in terms of the soil C balance. Soil respiration at our site was noticeably greater, relative to the incident litterfall amount, than soil respiration in other tropical and temperate forests probably owing to the larger total belowground C allocation by emergent trees. Overall, this study suggests the arrangement of emergent trees with larger DBH and their belowground C allocation could be primary factors controlling spatial variations in soil respiration in the tropical rainforest.     

Characterization of water soluble organic matter in soils by size exclusion chromatography and fractionation with polyvinylpyrrolidone

Water extracts were obtained from four types of soils (Brown Lowland soil, Yellow soil with manure application for 6 years, non-allophanic Andosol, and allophanic Andosol), and the organic matter in the water extracts was fractionated according to the solubility in acid and adsorption onto polyvinylpyrrolidone (PVP). For the water extracts and their fractions, the amounts of organic C, total N, and anthrone-reactive C (ARC) were analyzed, and high performance size exclusion chromatography (HPSEC) was carried out. The PVP-non-adsorbed fulvic acid (FA) fraction accounted for the largest proportion of the total water-soluble organic C, ranging from 52% for the Yellow soil to 96% for the allophanic Amdosol, followed by the PVP-adsorbed FA and humic acid (HA) fractions. The water extract of the allophanic Andosol was characterized by the lack of HA fraction and a small proportion of PVP-adsorbed FA fraction. For all the water extract samples, more than 90% of the ARC was recovered in the PVP-non-adsorbed FA fraction. The proportion of ARC in the total organic C in the fraction was also highest in the PVP-non-adsorbed FA fraction. The molecular weight (MW) of the humic substances (HS) at peak maximum was estimated at 1,300 Da for the water extracts and their fractions from the Brown Lowland soil and non-allophanic Andosol samples by HPSEC using polyethylene glycols as MW standards. Manure application increased the MW of HS in the HA and PVP-adsorbed FA fractions. On the other hand, only a small amount of HS was found in the water extract of the allophanic Andosol by HPSEC.     

Sequential synaptic excitation and inhibition shape readiness discharge for voluntary behavior

How do animals initiate voluntary behavior? A key phenomenon in neuroscience is the readiness or preparatory neural activity in specific regions of the animal brain. The neurons and synaptic mechanisms mediating this activity are unknown. We found that the readiness discharge is shaped by sequential synaptic excitation and inhibition in the brain of crayfish (Procambarus clarkii). The readiness discharge neurons extended axon collaterals that appeared to activate recurring local interneurons. Therefore, we propose that the readiness discharge is formed by sequential synaptic events within the brain without feedback signals from downstream ganglia. The circuit involved is suited for signal processing for self-generated voluntary initiation of behavior.