Fate of resting cysts of Alexandrium spp. ingested by Perinereis nuntia (Polychaeta) and Theola fragilis (Mollusca)

The ingestion of resting cysts of Alexandrium spp. by Perinereis nuntia (Polychaeta) and Theola fragilis (Mollusca) was experimentally examined in the laboratory. P. nuntia and T. fragilis were cultured in bottom sediment containing a high density of Alexandrium cysts under dark conditions. Moreover, to evaluate the degree and consequence of being ingested, the density of cysts in the control sediment (no macrobenthic organisms) and the germination capability of the cysts in the faecal pellets of the two species of macrobenthos were examined.Cysts in the culture sediment were found to be ingested by both P. nuntia and T. fragilis. No difference in the density of cysts between the sediments cultured with and without P. nuntia was observed. However, the density of cysts in the sediments with T. fragilis decreased by 24% compared to the density in the control sediment. It is possible that most of the cysts ingested were digested by T. fragilis. The rate of Alexandrium cyst digestion by this species is estimated 594 cysts/individual/day. It is estimated that 91% of the cysts ingested by T. fragilis were partially or totally digested and only 9% were excreted in a viable state during the experiment. Thus, T. fragilis has a stronger affect on the abundance of Alexandrium cysts compared with P. nuntia.No significant difference was observed between the germination success of the cysts from faecal pellets of P. nuntia and T. fragilis compared to the cysts in the control sediment. If, however, the necessary light for the cysts to germinate is cut off by being enclosed within the faecal pellet, the germination rate of cysts from the faecal pellets may be suppressed.     

Evolution of the A+T-rich region of mitochondrial DNA in the melanogaster species subgroup of Drosophila

We determined the nucleotide sequences of two regions in the A+T-rich region of mitochondrial DNA (mtDNA) in the siI and siII types of D. simulans, the maII type of D. mauritiana, and D. sechellia. The sequences were aligned with those of the corresponding regions of siIII of D. simulans and maI of D. mauritiana, D. melanogaster, and D. yakuba. The type I and type II elements and the T-stretches were detected in all eight of the mtDNA types compared, indicating that the three elements are essential in the A+T-rich region of this species subgroup. The alignment revealed several short repetitive sequences and relatively large deletions in the central portions of the region. In the highly conserved sequence elements in the type II elements, the substitution rates were not uniform among lineages and acceleration in the substitution rate might have been due to loss of functional constraint in the stem–loop-forming sequences predicted in the type II elements. Patterns of nucleotide substitutions observed in the A+T-rich region were further compared with those in the coding regions and in the intergenic regions of mtDNA. Substitutions between A and T were particularly repressed in the highly conserved sequence elements and in the intergenic regions compared with those in the A+T-rich region excluding the highly conserved sequence elements and in the fourfold degenerate sites in the coding regions. The functional and structural characteristics of the A+T-rich region that might be involved in this substitutional bias are discussed.     

Unusually large numbers of electrons for the oxidation of polyphenolic antioxidants

Reaction mechanisms of polyphenolic antioxidants were studied using electrochemical methods (flow column electrolysis and cyclic voltammetry). In flow column electrolysis, the numbers (ns) of electrons involved in the oxidation of catechols (chlorogenic acid and caffeic acid) became larger than two (i.e. the number of -OH moieties) at pH > 7; the n-values finally reached ca. 4 at pH 10. Other polyphenols including catechin, ellagic acid, and curcumin exhibited higher n-values than the numbers of -OH moieties in the whole pH range studied (4 < pH < 10). Such unusually large n-values for polyphenols were found to correlate to their irreversible behavior in cyclic voltammetry. A digital simulation analysis of the voltammograms of chlorogenic acid clearly showed that the electrode reaction at higher pHs can be elucidated in terms of a quasi-reversible electron transfer followed by a chemical reaction and also suggested that the chemical reaction is of second order to the concentration of chlorogenic acid, i.e. a dimerization reaction. In a similar manner, polyphenolic antioxidants generally undergo certain chemical reactions on the occasion of their oxidation. As a result, some oxidizable, phenolic -OH moieties are reproduced in the polymeric products. The unusually large n-values of polyphenols and thus their higher radical scavenging activities may be ascribed to such reproduction of -OH moieties by oxidative polymerization.     

Structure of the gene encoding the muscle-specific subunit of human phosphoglycerate mutase

We report the isolation and analysis of genomic clones containing the entire gene encoding the muscle-specific subunit of human phosphoglycerate mutase. The gene spans 2.83 kilobase pairs and has a three-exon/two-intron structure that is similar to the organization of the human 2,3-bisphosphoglycerate mutase gene (Joulin, V., Garel, M.-C., LeBoulch, P., Valentin, C., Rosa, R., Rosa, J., and Cohen-Solal, M. (1988) J. Biol. Chem. 263, 15785-15790), in that the second introns of both genes are localized precisely at the same position. A canonical TATA box and an inverted CCAAT box are present immediately upstream of this gene. Comparison with other muscle-specific enzyme genes reveals a conserved 9-base pair element (GGGGCTGGG) in the 5'-flanking region that may be associated with the expression of genes encoding muscle-specific enzymes.     

Pharmacogenetic modulation of orexin neurons alters sleep/wakefulness states in mice

Hypothalamic neurons expressing neuropeptide orexins are critically involved in the control of sleep and wakefulness. Although the activity of orexin neurons is thought to be influenced by various neuronal input as well as humoral factors, the direct consequences of changes in the activity of these neurons in an intact animal are largely unknown. We therefore examined the effects of orexin neuron-specific pharmacogenetic modulation in vivo by a new method called the Designer Receptors Exclusively Activated by Designer Drugs approach (DREADD). Using this system, we successfully activated and suppressed orexin neurons as measured by Fos staining. EEG and EMG recordings suggested that excitation of orexin neurons significantly increased the amount of time spent in wakefulness and decreased both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep times. Inhibition of orexin neurons decreased wakefulness time and increased NREM sleep time. These findings clearly show that changes in the activity of orexin neurons can alter the behavioral state of animals and also validate this novel approach for manipulating neuronal activity in awake, freely-moving animals.     

Mature leaf selection of Japanese macaques: effects of availability and chemical content

Mature leaf food selection of Japanese macaques was studied in two different altitudinal zones of Yakushima: in the coniferous (1000–1200 m) and coastal forests (0–200 m). Logistic regression analysis was conducted to reveal the effect of chemical [neutral detergent fibre (NDF), crude protein, crude ash, crude lipid, condensed tannin, hydrolysable tannin and crude protein/NDF ratio] and availability properties (density of trees and total basal area) on the macaques' choice between the major food leaves and the rarely eaten or non-food leaves. In both forests, macaques selected leaves with a high crude ash and crude protein content, or a high crude protein/NDF ratio, as major foods. In the coniferous forest, macaques selected leaves with less condensed tannin, but this tendency was absent in the coastal forest. This was because macaques in the coniferous forest suffer from a greater risk of ingesting large amounts of condensed tannins, as their feeding time on mature leaves is seven times as long as that in the coastal forest. Among the chemical and availability properties, stepwise multiple regression analysis revealed that the number of trees (ha⁻¹) was the only significant factor explaining the variations in feeding time among major food leaves, both in the coniferous and coastal forests. The present results suggest that the effect of travelling cost, which can be reduced by selecting common trees, exceeds the benefits gained by selecting high-quality foods.     

Comparative study of additive basal area of conifers in forest ecosystems along elevational gradients

We examined the basal area of two life forms (conifers vs. broadleaf trees) along elevational gradients on Yakushima Island, Japan and on two series of geological substrate on Mount Kinabalu, Borneo. On Yakushima, total stand basal area abruptly increased from 700 to 1,050 m in accordance with the high dominance of conifers, indicating the presence of additive basal area of conifers in conifer–broadleaf mixed forests at higher elevations (1,050–1,300 m). Along two substrate series on Kinabalu, some forests at higher elevations (1,860–3,080 m) showed relatively high dominance of conifers, but conifer basal area did not appear to be additive. Conifers were emergents above the canopy of broadleaf trees in mixed forests on Yakushima, but two life forms usually coexisted in the single-story canopy in mixed forests on Kinabalu. Litterfall rate as a surrogate of productivity decreased with decreasing temperature along elevation on both the sites, but the rate of decrease was slower on Yakushima, where mixed forests at higher elevations showed relatively high rates. Thus, we suggest that additive basal area of conifers was linked to their emergent status, and that it enhanced productivity by complementary use of light by two life forms that occupy different stories. On Yakushima, typhoons are a major disturbance, but do not severely limit the height growth of conifers, allowing the development of two-story mixed forests. On Kinabalu, a major disturbance is El Niño-driven drought, and hydraulic limitation to tree height may explain the non-additive and non-emergent nature of conifers.     

Topography-specific emergence of fungal fruiting bodies in warm temperate evergreen broad-leaved forests on Yakushima Island,Japan

We conducted line route censuses of fungal fruiting bodies from August to September in 2005 and 2006 along ridges and valleys and compared the differences in the encounter rates of fungal fruiting bodies (= fruiting bodies seen per census kilometer) between types of topography and between fungal functional groups (i.e., ectomycorrhizal and saprobic fungi) in warm temperate evergreen broad-leaved forests on Yakushima Island, Japan. We found 251 fungal fruiting bodies (26 families, 50 genera, and 65 species) in total, including 51 bodies from Tricholomataceae, 41 from Russulaceae, 25 from Boletaceae, and 19 from Amanitaceae. The encounter rate of ectomycorrhizal fungi was greater at the ridge route (26.7 unit/km) than at the valley route (8.7 unit/km) and that of saprobic fungi was greater at the valley route (25.0 unit/km) than at the ridge route (12.5 unit/km). In addition, we conducted 7-year intermittent sampling and identified 40 families, 96 genera, and 142 species. The topography-specific emergence pattern of the intermittent sampling method was similar to that of the line census method. The fungal species composition in this study was possibly affected by a topographic gradient for both fungal functional groups through soil moisture, nutrient availability, and host tree distribution.