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The genome size (C-value) of a species indicates the total amount of DNA included in its haploid chromosomes. It is one of the fundamental characteristics that relate closely to the evolution of organisms. Information on molluskan C-values is limited despite the abundance of morphological diversity. Therefore, to better understand molluskan genome evolution, we conducted a comprehensive survey of the C-values and AT content of 146 species in four molluskan classes by flow cytometry. The difference in AT content was found to be related to an increase in C-value in gastropods and cephalopods. For cephalopods, a positive correlation of AT content with the increase in chromosome number and C-value was observed from Nautilus pompilius and N. macromphalus (2n = 52) to the specialized groups of octopus (2n > 60) and squid (Sepiida and Teuthida; 2n = 92–112). In contrast, a negative correlation between C-value and AT content in gastropods was demonstrated from the limpet group Patellogastropoda (2n = 16–18) to the specialized group Neogastropoda (2n = 26–72). Our data suggest at a likely positive correlation between AT content and C-value in the cephalopods lineages but a negative correlation between them in the gastropod lineages. Furthermore, the reduction of the C-value in the Bivalvia lineage could not have been caused by the selective deletion of AT-rich regions. Our study adds valuable data to the currently limited knowledge base of molluskan C-values, which will provide important information for future genome projects in mollusks.

The hydrothermal vent crab Gandalfus yunohana is found along the Izu-Ogasawara Arc in the north-western Pacific at depths from 420 to 1400 m. To study the larval developmental characteristics of this vent endemic species, we collected adult crabs from a depth of 445 m in May 2005 from the Kaikata Seamount (26°42.607′N, 141°04.457′E). These individuals were maintained at atmospheric pressure and temperature (15 and 18°C) for several months, until two females spawned and released larvae. Larvae were maintained at atmospheric pressure and at five different temperatures ranging from ∼18 to 30°C and fed Artemia sp. At ∼18°C, no larvae survived until the second zoeal stage. Some larvae reached the second or third zoeal stages when reared at ∼21°C. At 24-30°C, six individuals metamorphosed into the megalopal stage following a fifth or sixth zoeal stage 34-60 d after hatching. Megalopae swam actively, but they eventually died 58-104 d after hatching and showed no signs of moulting into the juvenile crab stage. Newly hatched first stage zoeae were phototactic, and we observed relatively high temperature requirements for larval survival and development. These facts suggest that zoeae may be distributed relatively high in the water column in warmer near-surface waters during their planktotrophic development. This is the first report of successful larval rearing of any species of bythograeid crabs. Our study establishes the conditions under which the megalopae moult to the first crab stage, laying the groundwork for future experiments.

:  From the two species of bivalves, Calyptogena soyoae around a cold seep and Bathymodiolus septemdierum near hydrothermal vents in the sea, sterols were isolated using high‐pressure liquid chromatography analysis of the lipid fraction guided by characteristic 1H NMR signals of the sterol skeleton. The minor sterol composition of C. soyoae included 24‐methylenecycloartanal, cycloeucalenol, and obtusifoliol, which are known phytosterols. From B. septemdierum, lathosterol and cholesterol as main sterols together with more diverse sterols were obtained. The difference between these species and their sterol contents is most likely because of feeding modes and metabolism of nutrients from their habitat.

The first zoeal stage of Gandalfus yunohana (Takeda, Hashimoto & Ohta, 2000) is described and illustrated based on laboratory-hatched material. This is the first time that this has been accomplished for known species in the family Bythograeidae. Le premier stade zoé de Gandalfus yunohana (Takeda, Hashimoto & Ohta, 2000) est décrit et illustré à partir de matériel éclos en laboratoire. Ceci est une première pour une espèce connue de la famille des Bythograeidae.

We have studied phase transition of superfluid 3He in 97.5% porosity aerogel by NMR method. Above 1.0 MPa, superfluid phase transition has been observed. The transition temperature Tca is strongly suppressed from its bulk value. The Pressure-Temperature diagram suggests that superfluid phase will not appear below near 0.8 MPa. The A-B phase transition has been observed above 1.3 MPa, below which a state of superfluid phases remains to be identified. The temperature dependence of NMR frequency shifts Δf in the A-like and the B-like phases are almost linear at pressures below 2.4 MPa. We obtained the differential coefficient of NMR frequency shifts ∂(Δf)/∂(T/Tca) at 0.9Tca as a function of pressure, and it suggests that superfluid phase will not appear below near 0.8 MPa which is the same pressure estimated by P-T diagram.

A common littoral barnacle, Balanus glandula (Crustacea, Cirripedia) from the west coast of North America has become established in the mid-littoral zone of harbors on the Pacific side of northern Honshu, Japan. The new immigrant occupies space in the lower half of the Chthamalus and Balanus albicostatus zones, and in the upper fringe of the Semibalanus cariosus zone. However, the species has not been detected in harbors along the Sea of Japan, south of the Ozika Peninsula, northern Honshu, and to the north and east of Kushiro, Hokkaido. Considering its present distribution, shell sizes, and abundance, it is most likely that it was introduced into 3 separate port areas in NE Honshu, Japan, during the last 20 to 40 yr, probably by anthropogenic activities. It was apparently also introduced to the La Plata estuary, Argentina, during the same period. B. glandula is becoming a dominant littoral zone species, especially in embayments, largely at the expense of the tropical endemic B. albicostatus in the upper littoral fringe. Taking into account the biogeographical distribution of common Japanese barnacles in relation to water temperature, the future distribution of the newly introduced species is considered.

This study used morphometric analyses to compare the structure of the third antennular segment, also called the attachment organ, in cyprid larvae from cirripede species representing a diverse set of taxonomic groups. The aim was to investigate the degree of morphological variation in view of the diversity of habitats, settlement substrata, and modes of life found in the Cirripedia. In all cyprids the third segment features a flat surface (the attachment disc) covered with small cuticular villi thought to function in adhesion. The parameters analyzed were the angle of this disc relative to the long axis of the antennule, its shape (outline), the density of cuticular villi, and the type of cuticular structure encircling the disc. The 10 species studied came from most major groups of cirripedes, and comprised shallow-water forms inhabiting hard bottoms (Capitulum mitella, Pollicipes pollicipes, Semibalanus balanoides, Austrominius modestus, Megabalanus rosa), sublittoral forms (Verruca stroemia, Scalpellum scalpellum), epibiotic forms settling on live, soft tissues (Balanus spongicola, Savignium crenatum), and a parasite (Peltogaster paguri). Significant structural variation was found among the species, but due to limited taxon sampling it was unclear whether the differences relate to ecological factors or phylogenetic affiliation. The disc perimeter is guarded by either a series of long and thin cuticular fringes overreaching the rim of the disc (= a velum) or a few low, but very broad cuticular flaps (= a skirt). The presence of a velum (in all rocky-shore species) or a skirt (all other species) around the attachment disc was the only parameter that was clearly correlated with habitat. The shape of the third antennular segment varied from a symmetrical bell shape with a distally facing attachment disc having a circular disc outline, to segments that were elongated in side view, with a very tilted ventral disc surface having an elliptical disc outline. The bell shape may be most common in forms from rocky shores, but in our test of morphometric parameters only Scalpellum scalpellum (sublittoral), Savignium crenatum (epibiotic in corals), and Peltogaster paguri (parasitic) had shapes that differed significantly from the other species. The density of villi on the attachment disc varied significantly, but also showed no clear-cut correlation with substratum or habitat. Attachment organ structure is clearly the most variable feature in cirripede cyprids. To evaluate the degree to which attachment organ structure is correlated with habitat, settlement substratum, and mode of life, future studies should employ a more refined statistical analysis on an enlarged dataset, with much increased taxon sampling and a more multifaceted definition of ecological variables.

A common littoral barnacle,Balanus glandulaDarwin, 1854 (Crustacea, Cirripedia) from the west coast of North America has become established in the mid-littoral zone of harbors on the Pacific side of northern Honshu, Japan. The new immigrant occupies space in the lower half of theChthamalusspp. andBalanus albicostatuszones, and in the upper fringe of theSemibalanus cariosuszone. However, the species has not been detected in harbors along the Sea of Japan, south of the Ozika Peninsula, northern Honshu, and to the north and east of Kushiro, Hokkaido. Considering its present distribution, shell sizes, and abundance, it is most likely that it was introduced into 3 separate port areas in NE Honshu, Japan, during the last 20 to 40 yr, probably by anthropogenic activities. It was apparently also introduced to the La Plata estuary, Argentina, during the same period.B. glandulais becoming a dominant littoral zone species, especially in embayments, largely at the expense of the tropical endemicB. albicostatusin the upper littoral fringe. Taking into account the biogeographical distribution of common Japanese barnacles in relation to water temperature, the future distribution of the newly introduced species is considered.

Within years of its introduction, the North American barnacleBalanus glandulaDarwin, 1854 became an abundant member of rocky intertidal communities in Japan and Argentina. To determine the regional sources of these invasions, we compared mitochondrial cytochrome c oxidase subunit 1 (COI) and nuclear elongation factor 1 alpha (EF1) genotypes of native and introduced populations. Previously described population structure at these loci in North America conferred geographic information to genotypes.B. glandulafrom Argentina and southern to central California shared genotypes not found in other native populations.B. glandulafrom Japan and the northeastern Pacific (Puget Sound and Alaska) were differentiated from other populations by the presence of a nearly fixed nucleotide in EF1 and contained all 3 major haplotype groups of COI. These patterns indicate that sources ofB. glandulain Japan and Argentina are largely from Alaska/Puget Sound and California, respectively. The broad similarity of mean seawater temperatures among introduced and native regions may have facilitated these invasions. The presence of greater variation in air temperatures in the invaded than native regions raises the possibility that temperature-related selection may play an important role in the evolution of these invasive populations. We found no evidence of multiple geographic sources ofB. glandulain Japan and Argentina, nor of genetic bottlenecks in either invaded region.

It is observed that the A-like phase and the B-like phase, which are superfluid phases of 3He in high porosity silica aerogel as an impurity, coexist stably [1]. In this coexisting state, we showed by NMR experiments with radial gradient magnetic field that the A-like phase is in the edge part of a cylindrical aerogel and the B-like phase is in the central part of that [2]. It is proposed that the A-like phase might be more stabilized in globally anisotropic aerogel. According to this proportion, the aerogel might be globally anisotropic in edge part. In order to study whether the aerogel is globally anisotropic, we have performed optical birefringence experiment on aerogel samples in the same batch. This optical method is a useful tool to characterize a global anisotropy of aerogel [3]. Then, we found that aerogel samples are not globally anisotropic. Therefore, there are another mechanism for the A-B phase separation in radial direction.