Whistle variability of Guiana dolphins in South America: Latitudinal variation or acoustic adaptation?

A previous comparison of whistles using data sampled at 48 kHz suggested that certain frequency parameters vary along a latitudinal gradient. This geographical pattern may be biased because whistles sampled at higher frequencies could potentially have very different frequency contents. The current study compared the acoustic parameters of Guiana dolphin (Sotalia guianensis) whistles recorded at a higher sampling rate (96 kHz) and from groups occupying two never before sampled sites, Benevente Bay, Espírito Santo, Brazil, and Formosa Bay, Rio Grande do Norte, Brazil, with recordings of other populations in South America. By only considering data sampled at a rate of at least 96 kHz, we aimed to detect differences in whistles across locations. Contrary to previous findings, our analyses do not indicate any clear separation between northern and southern populations based on whistles, and do not corroborate the hypothesis of latitudinal acoustic variation in this species. The variation in Guiana dolphin whistle parameters found here appears to be influenced by latitude to some extent, but several other factors, including sampling method, environmental fluctuations, and social influence on vocal learning, may be confounding the detection of a geographic pattern in these whistle samples.     

Double assembly composed of lectin association with columnar molecular assembly of cyclic tri-beta-peptide having sugar units

A novel double assembly was prepared by association between a columnar molecular assembly of cyclic tri-beta-peptides having sugar units and lectins. The NMR, FT-IR, and circular dichroism (CD) spectroscopy as well as computational calculations revealed that this compound took a flat and C3 symmetrical conformation and that the amide N-H and C=O groups protruded vertically to the ring plane. This disk-shaped molecule stacked one by one to form a columnar structure via intermolecular hydrogen bonds between the amide groups. WGA lectin moderately bound to this columnar assembly to form a double assembly. Another lectin (Con A) disturbed the columnar structure upon strong binding, and RCA lectin showed no binding. Fluorescence spectroscopy revealed that the association between WGA lectin and columnar assembly of cyclic glycopeptide could be achieved due to the high density of the hydroxyl groups on the assembly surface (cluster effects). Interestingly, after cross-linking the lectins bound to the columnar assembly (the double assembly) by glutaraldehyde, the core column of cyclic tri-beta-peptides could be washed away to leave the protein nanotube.     

Habitat use by endangered Japanese crayfish (<Emphasis Type="Italic">Cambaroides japonicus</Emphasis>) in low-gradient streams of southern Hokkaido,Japan: reach and microhabitat-scale analysis

The Japanese crayfish (Cambaroides japonicus), the only native crayfish in Japan, is endangered and has experienced rapid population declines. We surveyed the habitat requirements of Japanese crayfish at the reach and microhabitat scales in semi-natural low-gradient streams. Habitat use by Japanese crayfish differed between the spatial scales. Reach-scale analysis revealed that the bed slope was the only positive predictor of crayfish density. This finding indicates that relatively high-gradient reaches, such as headwater reaches, are an important habitat for the conservation of Japanese crayfish in low-gradient streams. Microhabitat-scale analysis showed that crayfish density was positively affected by substrate coarseness and the presence of instream vegetation cover (bank vegetation, woody debris, and leaf patches), whereas it was negatively affected by distance from the stream edge. Coarse substrates and vegetation cover may function as shelters from water flows and predators during low flow periods. The use of stream-edge areas may allow quick access to refugia and enable the crayfish to avoid unexpected flood disturbance and predation. These habitat characteristics should therefore be preserved for the conservation of Japanese crayfish, and scale-dependent habitat characteristics should be considered in future conservation plans.     

Artificial ladder-shaped polyethers that inhibit maitotoxin-induced Ca2+ influx in rat glioma C6 cells

Maitotoxin (MTX) is a ladder-shaped polyether produced by the epiphytic dinoflagellate Gambierdiscus toxicus. It is known to elicit potent toxicity against mammals and induce influx of Ca(2+) into cells. An artificial ladder-shaped polyether possessing a 6/7/6/6/7/6/6 heptacyclic ring system, which was designed for elucidating interactions with transmembrane proteins, was found to be the most potent inhibitor against MTX-induced Ca(2+) influx that has ever been reported.     

Discovery of CS-2100, a potent, orally active and S1P3-sparing S1P1 agonist

S1P(3)-sparing S1P(1) agonists have attracted attention as a suppressant of autoimmunity with reduced side effects. Our synthetic efforts and extensive SAR studies led to the discovery of 10b named CS-2100 with the EC(50) value of 4.0 nM for human S1P(1) and over 5000-fold selectivity against S1P(3). The in vivo immunosuppressive efficacy was evaluated in rats on host versus graft reaction and the ID(50) value was determined at 0.407mg/kg. The docking studies of CS-2100 with the homology model of S1P(1) and S1P(3) showed that the ethyl group on the thiophene ring of CS-2100 was sterically hindered by Phe263 in S1P(3), not in the case of Leu276 in S1P(1). This observation gives an explanation for the excellent S1P(3)-sparing characteristic of CS-2100.     

Higher ghrelin and lower leptin secretion are associated with lower LH secretion in young amenorrheic athletes compared with eumenorrheic athletes and controls

Amenorrhea is common in young athletes and is associated with low fat mass. However, hormonal factors that link decreased fat mass with altered gonadotropin pulsatility and amenorrhea are unclear. Low levels of leptin (an adipokine) and increased ghrelin (an orexigenic hormone that increases as fat mass decreases) impact gonadotropin pulsatility. Studies have not examined luteinizing hormone (LH) secretory dynamics in relation to leptin or ghrelin secretory dynamics in adolescent and young adult athletes. We hypothesized that 1) young amenorrheic athletes (AA) would have lower LH and leptin and higher ghrelin secretion than eumenorrheic athletes (EA) and nonathletes and 2) higher ghrelin and lower leptin would be associated with lower LH secretion. This was a cross-sectional study. We examined ghrelin and leptin secretory patterns (over 8 h, from 11 PM to 7 AM) in relation to LH secretory patterns in AA, EA, and nonathletes aged 14-21 yr. Ghrelin and leptin were assessed every 20 min and LH every 10 min. Groups did not differ for age, bone age, or BMI. However, fat mass was lower in AA than in EA and nonathletes. AA had lower LH and higher ghrelin pulsatile secretion and AUC than nonathletes and lower leptin pulsatile secretion and AUC than EA and nonathletes. Percent body fat was associated positively with LH and leptin secretion and inversely with ghrelin. In a regression model, ghrelin and leptin secretory parameters were associated independently with LH secretory parameters. We conclude that higher ghrelin and lower leptin secretion in AA related to lower fat mass may contribute to altered LH pulsatility and amenorrhea.     

Prostaglandin E₂ increases both osteoblastic and osteoclastic activity in the scales and participates in calcium metabolism in goldfish

Using our original in vitro assay system with goldfish scales, we examined the direct effect of prostaglandin E? (PGE?) on osteoclasts and osteoblasts in teleosts. In this assay system, we measured the activity of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as respective indicators of each activity in osteoblasts and osteoclasts. ALP activity in scales significantly increased following treatment at high concentration of PGE?(10?? and 10?? M) over 6 hrs of incubation. At 18 hrs of incubation, ALP activity also significantly increased in the PGE? (10?? to 10?? M)-treated scale. In the case of osteoclasts, TRAP activity tended to increase at 6 hrs of incubation, and then significantly increased at 18 hrs of incubation by PGE? (10(-7) to 10?? M) treatment. At 18 hrs of incubation, the mRNA expression of osteoclastic markers (TRAP and cathepsin K) and receptor activator of the NF-κB ligand (RANKL), an activating factor of osteoclasts expressed in osteoblasts, increased in PGE? treated-scales. Thus, PGE? acts on osteoblasts, and then increases the osteoclastic activity in the scales of goldfish as it does in the bone of mammals. In an in vivo experiment, plasma calcium levels and scale TRAP and ALP activities in the PGE?-injencted goldfish increased significantly. We conclude that, in teleosts, PGE? activates both osteoblasts and osteoclasts and participates in calcium metabolism.     

CHMP5 is essential for late endosome function and down-regulation of receptor signaling during mouse embryogenesis

Charged MVB protein 5 (CHMP5) is a coiled coil protein homologous to the yeast Vps60/Mos10 gene and other ESCRT-III complex members, although its precise function in either yeast or mammalian cells is unknown. We deleted the CHMP5 gene in mice, resulting in a phenotype of early embryonic lethality, reflecting defective late endosome function and dysregulation of signal transduction. Chmp5-/- cells exhibit enlarged late endosomal compartments that contain abundant internal vesicles expressing proteins that are characteristic of late endosomes and lysosomes. This is in contrast to ESCRT-III mutants in yeast, which are defective in multivesicular body (MVB) formation. The degradative capacity of Chmp5-/- cells was reduced, and undigested proteins from multiple pathways accumulated in enlarged MVBs that failed to traffic their cargo to lysosomes. Therefore, CHMP5 regulates late endosome function downstream of MVB formation, and the loss of CHMP5 enhances signal transduction by inhibiting lysosomal degradation of activated receptors.