Analysis of the relationship between growth and sexual maturation in Phacosoma japonicum (Bivalvia: Veneridae)

The relationship between shell growth and sexual maturation was studied in the venerid bivalve Phacosoma japonicum (Reeve) based on specimens from six populations around the Japanese coast in 1991 and 1992. A distinct latitudinal variation in the patterns of shell growth and gonad development was detected. Speciments from northern populations are characterized by slower rates of gonad development, later offset of interval of shell growth, and larger shell size at a given age than those from southern populations, excluding the population from the Ariake Bay, Kyushu. These data indicate the presence of a tradeoff between reproductive effort and continued growth in this species. However, in all populations bivalves attain sexual maturity before ending shell growth. First sexual maturity occurs at a shell size of about 60% of the maximum asymptotic shell height. Maximum reproductive effort appears to start when the energy available for shell growth (i.e., the yearly growth rate of shell weight) attains a maximum. These relationships between shell growth and sexual maturation were also confirmed in some other bivalve species.     

An unusual archosaurian from the marine Triassic of China

A new Triassic archosaurian from China shows a number of aquatic specializations, of which the most striking is the extreme lateral compression of the long tail. Others that may also reflect aquatic adaptations include platelike scapula and coracoid, elongate neck with extremely long and slender ribs, and reduction of osteoderms. In contrast, its pelvic girdle and hind limb have no aquatic modifications. Anatomic features, taphonomy, and local geological data suggest that it may have lived in a coastal–island environment. This lifestyle, convergent with some Jurassic marine crocodyliforms that lived at least 40 million years later and the saltwater species of extant Crocodylus, contradicts with the prevailing view that Triassic archosaurians were restricted to nonmarine ecosystems. Its mosaic anatomy represents a previously unknown ecomorph within primitive archosaurians.Electronic Supplementary Material  Supplementary material is available for this article at     

Gasification and smelting system using oxygen blowing for plastic waste including polyvinyl chloride

A new type of waste gasification and smelting system using oxygen blowing based on high-temperature metallurgy, was developed by Sumitomo Metals, Japan. This system can steadily gasify and melt not only municipal waste, but also plastic waste and polyvinyl chloride (PVC) waste by using a top-blow oxygen lance together with sideways-blow oxygen lances. As a result of gasification in the high-temperature reducing atmosphere and rapid gas cooling, dioxin-free, high-calorie purified gas was produced. Ash components in the wastes were smelted in a high-temperature reducing atmosphere, and high-quality slag free of heavy metals was produced. Most of the chlorine in the wastes was converted into hydrogen chloride in the off gas. The hydrogen chloride can be recovered as hydrochloric acid or chlorine, which are recyclable to PVC manufacturing.     

Local Circulation with Aeolian Dust on the Slopes and Foot Areas of the Tianshan and Kunlun Mountains around the Taklimakan Desert, China

Four automatic weather stations (AWS) were installed on the slopes and foot areas of the Tianshan and Kunlun Mountains along a longitude of 80 degrees east: (1) Taglak 2400 m a.s.l., (2) Aksu 1000 m, (3) Kartash 2800 m, and (4) Qira 1700 m. These two slopes face the Taklimakan Desert. Tagliak lies on the southern slope of Tianshan, and Kartash on the northern slope of Kunlun. The meteorological characteristics of the mountainous regions were investigated using surface data obtained during an intensive observation period (IOP) in spring 2002. It was found that visibility on the slopes decreases in the daytime, and there is no relationship between visibility and wind speed in the mountainous areas. Two snow layers containing dust particles were observed in the snow cover in Taglak during the IOP in spring 2003. These results suggest that a warm air parcel containing aeolian dust climbs over the slopes of the mountainous areas, and dust particles in the mountainous areas are transported from the foot areas.     

Paralytic shellfish poison in the “hiogi” scallop Chlamys nobilis

Attempts were made to analyze the toxin composition of the toxic hiogi scallop Chlamys nobilis. The toxins were partially purified from the digestive glands by column chromatography using Bio-Gel P-2 and Bio-Rex 70 (H⁺ form), resulting in separation into protogonyautoxin (PX), gonyautoxin (GTX) and saxitoxin (STX) fractions. Their total potencies were scored to be <100 mouse units (MU), 3200 MU and 3700 MU, respectively. A 5-min hydrolysis with 0.1 N HCl enhanced the potencies of PX and GTX fractions to 450 MU and 12000 MU respectively, whereas no enhancement occurred in the STX fraction at all. Electrophoretic, thin-layer chromatographic and high performance liquid chromatographic analyses demonstrated that the PX fraction consisted mainly of GTX₈ and its epimer, the GTX fraction of GTX₅, GTX₆, along with two unidentified toxins, and the STX fraction exclusively of two unidentified toxins. This rather unique composition suggested a complex metabolism of PSP in this species.     

2-Nitroethenylbenzenes as natural products in millipede defense secretions

The white millipede Eucondylodesmus elegans Miyosi (Polydesmida: Doratodesmidae) secretes odoriferous droplets from the glands on both lateral surfaces of its body segments. The secretion was shown to be composed of a mixture of (1E)- and (1Z)-2-nitroethenylbenzenes (2-3 microg per millipede), identified by GC/MS analyses and synthesis. This is the first identification of these compounds as natural products. A granulated sugar block baited with the synthetic compound (more than 0.71 microg) demonstrated repellent activity against foraging wild ants, indicating that the compound functioned as a defense substance against potential predators. alpha,beta,2,3,4,5,6-d7-(1E)-2-Nitroethenylbenzene was detected by GC/MS analysis in the millipede secretion after feeding with alpha,beta,beta,2,3,4,5,6-d8-L-phenylalanine, indicating that L-phenylalanine is the precursor of these compounds.     

Discarded queen conch (<Emphasis Type="Italic">Strombus gigas</Emphasis>) shells as shelter sites for fish

Within the Caribbean millions of queen conch (Strombus gigas Linnaeus) are harvested each year and shells discarded randomly or as middens. Fish use of discarded conch shells was investigated in four different habitat types: sand, seagrass beds, mangrove forests, and coral reefs. The study was carried out in the waters off South Caicos, Turks and Caicos Islands (TCI), between October 2003 and January 2004. The density of discarded shells was greatest near coral reefs; however, the percentage of shells occupied by adult fish was higher in isolated shells on sand and in mangrove habitats. Juvenile fish also showed a preference for sheltering in conch shells relative to other microhabitat types on sandy plains and in mangrove and seagrass habitats. Differences in use of single shells by fish in different habitats were attributed to differences in piscivore abundance and habitat complexity. Although not all isolated shells were occupied by fish, all conch middens deposited by fishermen had fish inhabitants. Examination of fish use of conch middens in three habitat types and conch piles of one, three, and five shells constructed on sand found both fish diversity and abundance increased on conch middens of increasing size. This study suggests that disposal of conch shells as large middens in habitats of low complexity will increase the amount of shelter present and may enhance fish populations in these habitats.Communicated by J.P. Grassle, New Brunswick     

Body temperature independence of solar radiation in free-ranging loggerhead turtles,Caretta caretta,during internesting periods

Body temperatures, ambient water temperatures, light intensities and vertical positions (depth) of eight loggerhead turtles, Caretta caretta, were monitored by small recorders during internesting periods from 1991 through 1993 off Wakayama Prefecture, Japan. Body temperatures of eight loggerhead turtles were higher than ambient water temperatures through-out their internesting periods. Light intensities were compared with body temperatures and no evidence was obtained to suggest that the raised body temperatures were caused by the direct influence of solar radiation. Body temperatures were kept higher than water temperatures in cloudy weather or even at night. Mean thermal differences between body and water temperatures were significantly different among individuals, and larger turtles had a greater mean thermal difference. Elevations in body temperatures of adult loggerhead turtles can reasonably be assumed to result from the accumulation of metabolically produced heat. Surfacing times (spent at depths shallower than 2 m) of seven turtles were only 10.3 to 38.9% of their internesting periods, with the exception of one turtle who spent 66.3% of her time at the surface. Loggerhead turtles did not seem to bask positively at the sea surface to absorb radiative heat.     

Enantioselective recognition of mono-demethylated methoxychlor metabolites by the estrogen receptor

Metabolites of methoxychlor such as 2-(p-hydroxyphenyl)-2-(p-methoxyphenyl)-1,1,1-trichloroethane (mono-OH-MXC) and 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (bis-OH-MXC), have estrogenic activity. Mono-OH-MXC is a chiral compound in which the carbon atom bridging two benzene rings is the chiral centre. In previous studies the estrogenic activity of racemic mono-OH-MXC has been measured, and the activity of each enantiomer of this compound has not yet been elucidated. In this study, we evaluated the estrogen receptor-binding activity of each enantiomer of mono-OH-MXC to clarify the enantioselective recognition by the estrogen receptor. (S)-mono-OH-MXC showed 3-fold higher binding activity than that of the (R) enantiomer. The activity of bis-OH-MXC was only 1.7-fold higher than that of (S)-mono-OH-MXC. This result suggests that the one hydroxy group and the orientation of the CCl3 group of mono- and bis-OH-MXCs are important for the interaction with the estrogen receptor. The result also points out the estrogenic activity of methoxychlor after metabolic activation in vivo, which predominantly produces the (S)-mono-OH-MXC, may be higher than estimated from the in vitro activity of racemic mixtures.