Single spaghetti tagging as a high-retention marking method for Japanese common sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis>

Populations of sea cucumbers, including the Japanese common sea cucumber Apostichopus japonicus, have been seriously depleted worldwide due to overfishing. Mark–recapture study is an efficient means of collecting ecological data. However, the use of such a method in sea cucumbers is difficult because they lack hard tissues in the body wall. Here we tested the viability of various tagging methods on A. japonicus. First, we applied conventional tags using four different methods [single spaghetti (T-bar) tagging, double spaghetti tagging, ribbon tagging, and Atkins tagging] to ten individuals per method in aquaria for 14 days. Of the methods used, single spaghetti tagging had the highest retention rate. Then we examined the retention rate of single spaghetti tags on ten individual sea cucumbers for up to approximately 6 months in rearing conditions. The single spaghetti tagging method showed a retention rate of 100% over at least 7 days, and 50% of the tags remained embedded after 56 days. The longest duration of tag retention was 174 days, at which time the experiment was terminated. These results indicate that single spaghetti tagging is reliable for both short- and longer-term studies, making it a useful tool for ecological and conservation studies in sea cucumbers.     

Onset of individual growth difference in larviculture of Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis> using fertilized eggs obtained from one female

We conducted a rearing experiment on Pacific bluefin tuna (PBT) larvae, which originated from one female broodstock, and determined the growth history of the larvae to clarify when the growth difference occurs. We investigated the otolith microstructure of the PBT larvae to examine the individual growth history and to predict the age and body size at the onset of individual growth difference. Since total length (TL) of fish can be back-calculated from otolith radius, we back-calculated TLs of 100 fish of 19 days post hatch (dph) divided into three size groups (small, intermediate, large). Growth difference was recognized from 3 dph (mouth opening), and the difference became larger thereafter. Growth of large-size fish was assumed to be promoted by the feeding conditions of PBT larvae.     

Occurrence of a temperate coastal flatfish,the marbled flounder Pseudopleuronectes yokohamae,at high water temperatures in a shallow bay in summer detected by acoustic telemetry

Fisheries Science - The marbled flounder Pseudopleuronectes yokohamae, a flatfish found in temperate coastal waters, is an important commercial species in the northwestern Pacific Ocean, but little...     

Reproductive biology of<Emphasis Type="Italic"> Pasiphaea japonica</Emphasis> females in Toyama Bay,central Japan

The reproductive biology of female Pasiphaea japonica, including the minimum size of females carrying embryos, spawning and hatching seasons, and brood size, was examined in Toyama Bay, central Japan, during 2004 through 2007. Sampling was conducted onboard a commercial seiner and a fisheries research vessel. The minimum size of ovigerous females was 47.7 mm body length. The percent occurrence of ovigerous females increased with body size, reaching 50% at 57.9 mm body length. Ovigerous females occurred all year round with a seasonal change in percent occurrence, ranging between 41.5 and 94.3% of the total observed females. Consequently, reproduction in females seems to occur throughout the year in Toyama Bay, with seasonal differences in reproductive intensity. Spawning intensity was high during April–July and October–January based on the occurrence of the early developmental stage of embryos, while hatching intensity was high in October–May based on the occurrence of embryos just before hatching. Brood sizes were similar at the same size of body length regardless of embryo stage, except just after spawning.     

Factors associated with canine skin extensibility in toy poodles

To assess factors for canine skin extensibility, our study investigated associations between the dogs’ skin extension index and the following factors, gender, age, neuter status, weight, coat color and six coat color related gene polymorphisms. Swab samples were collected from 69 toy poodles to extract DNA. The skin extension indices of the lower back and the neck were measured using the following formula: vertical height of the skin fold divided by body length multiplied by 100. The dogs’ age, weight, gender, neuter status and coat color were also recorded, as well as polymorphisms of the following six selected coat color related genes, Melanocortin 1 receptor, Tyrosinase-related protein 1, Melanophilin, Canine β-defensin-1, Major Facilitator Superfamily Domain Containing 12 and Agouti-signaling protein (ASIP). Univariable analysis showed there was a meaningful association between the lower back skin extension index and both gender and age (P<0.001 and P=0.048, respectively). Also, there was a possible association between the lower back skin extension index and ASIP Single nucleotide polymorphism (SNP) (R96C) (P=0.078). Linear model analysis showed there was a significant association between the lower back skin extension index and gender (P<0.001), and there was a tendency of the association between the lower back skin extension index and ASIP SNP (R96C) (P=0.098). In addition, there was an association between gender and age for the skin extension index. (P=0.048). Therefore, these results suggest that a greater risk of skin extensibility in toy poodle could be related to being female and the ASIP SNP (R96C), because these factors were associated with higher lower back skin extension index.     

Transient appearance of the epithelial invagination in the olfactory pit of chick embryos

In this study, immunohistochemical analysis has been performed using neuronal markers (GAP43, NCAM and PGP 9.5) to characterize the epithelial invagination in the medial wall of the olfactory pit in the chick embryos. At stages 26–27, the epithelial invagination was primarily composed of characteristic round-shaped cells, which were negative for neuronal markers. These cells were also found in the medial wall of the olfactory pit at stage 24, whereas the epithelial invagination was not observed at any stages other than stages 26–27. The possible relationship between the round-shaped cells and the migratory cells is discussed.     

Structure and bioactivity of thiosulfinates resulting from suppression of lachrymatory factor synthase in onion

In normal onion (Allium cepa), trans-S-1-propenyl-L-cysteine sulfoxide is transformed via 1-propenesulfenic acid into propanethial S-oxide, a lachrymatory factor, through successive reactions catalyzed by alliinase and lachrymatory factor synthase (LFS). A recent report showed that suppression of the LFS activity caused a dramatic increase in thiosulfinates previously reported as "zwiebelane isomers". After purification by recycle high-performance liquid chromatography and subsequent analyses, we established the planar structure of the putative "zwiebelane isomers" as S-3,4-dimethyl-5-hydroxythiolane-2-yl 1-propenethiosulfinate, in which two of the three molecules of 1-propenesulfenic acid involved in the formation gave the thiolane backbone, and the third molecule gave the thiosulfinate structure. Of at least three stereoisomers observed, one in the (2'R,3'R,4'R,5'R)-configuration was collected as an isolated fraction, and the other isomers were collected as a combined fraction because spontaneous tautomerization prevented further purification. Both fractions showed inhibitory activities against cyclooxygenase-1 and α-glucosidase in vitro.     

Ultrastructural and histochemical properties of the olfactory system in the japanese jungle crow, Corvus macrorhynchos

Although it has been commonly believed that birds are more dependent on the vision and audition than the olfaction, recent studies indicate that the olfaction of birds is related to the reproductive, homing, and predatory behaviors. In an attempt to reveal the dependence on the olfactory system in crows, we examined the olfactory system of the Japanese jungle crow (Corvus macrorhynchos) by histological, ultrastructural, and lectin histochemical methods. The olfactory epithelium (OE) of the crow occupied remarkably a small area of the nasal cavity (NC) and had the histological and ultrastructural features like other birds. The olfactory bulb (OB) of the crow was remarkably small and did not possess the olfactory ventricle. The left and right halves of the OB were fused in many cases. In the lectin histochemistry, soybean agglutinin (SBA) and Vicia villosa agglutinin (VVA) stained a small number of the receptor cells (RCs) in the OE and the olfactory nerve layer (ONL) and glomerular layer (GL) on the dorsocaudal region of the OB. Phaseolus vulgaris agglutinin-E (PHA-E) stained several RCs in the OE and the ONL and GL on the ventral region of the OB. These results suggest that 1) the crow has less-developed olfactory system than other birds, and 2) the dedicated olfactory receptor cells project their axons to the specific regions of the OB in the crow.     

Reduction of deoxynivalenol contaminating corn silage by short-term ultraviolet irradiation: a pilot study

We evaluated the effects of short-term (up to 60 min) irradiation of corn silage with ultraviolet (UV) light (intensity: 1.5 mW/cm(2) at 254 nm UV-C wavelength), along with constant stirring of the silage, on the concentration of deoxynivalenol (DON), a major feed-contaminating mycotoxin, and those of α-tocopherol (vitamin E) and β-carotene (pro-vitamin A). The initial DON concentration in artificially contaminated silage was set at approximately 60 μg/g dry silage weight. After irradiation, the level of DON was decreased significantly (P<0.05) by approximately 13 μg/g (22%) on average at 30 min, and by 12 μg/g (21%) at 60 min. However, the concentrations of the vitamins remained relatively unaffected. Although further improvement is needed, short-term UV irradiation seems a promising on-farm method for reducing the level of DON in feedstuffs.     

Altitudinal life-cycle and body-size variation in ground beetles of the genus Carabus (subgenus Ohomopterus) in relation to the temperature conditions and prey earthworms

The body size of univoltine insect species generally decreases with increasing altitude or latitude. This pattern may have arisen from adaptations to multiple factors that potentially affect body-size variation, such as temperature, food, and interspecific interactions. We examined altitudinal variations in life history and body size, and their relationships to temperature and food resources in two ground beetle species of the genus Carabus (subgenus Ohomopterus; C. tosanus and C. japonicus) in a mountainous area (altitude 860–1730 m) of Shikoku Island, Japan. Larvae of these species are specialist predators of earthworms. The body size of C. tosanus decreased with an increase in altitude. Carabus japonicus, which is much smaller than C. tosanus, exhibited similar sizes across altitudes, although it was not abundant at high altitudes. Available cumulative temperatures for larval development were limited at higher altitudes, and C. tosanus started reproducing 1 month earlier at higher than at lower altitudes. Earthworms (larval food) were less abundant at higher than at lower altitudes. This may imply that food resources also restrict the optimal body size of C. tosanus at higher altitudes.