Distribution of photoperiod-insensitive allele Ppd-A1a and its effect on heading time in Japanese wheat cultivars

The Ppd-A1 genotype of 240 Japanese wheat cultivars and 40 foreign cultivars was determined using a PCR-based method. Among Japanese cultivars, only 12 cultivars, all of which were Hokkaido winter wheat, carried the Ppd-A1a allele, while this allele was not found in Hokkaido spring wheat cultivars or Tohoku-Kyushu cultivars. Cultivars with a photoperiod-insensitive allele headed 6.9–9.8 days earlier in Kanto and 2.5 days earlier in Hokkaido than photoperiod-sensitive cultivars. The lower effect of photoperiod-insensitive alleles observed in Hokkaido could be due to the longer day-length at the spike formation stage compared with that in Kanto. Pedigree analysis showed that ‘Purple Straw’ and ‘Tohoku 118’ were donors of Ppd-A1a and Ppd-D1a in Hokkaido wheat cultivars, respectively. Wheat cultivars recently developed in Hokkaido carry photoperiod-insensitive alleles at a high frequency. For efficient utilization of Ppd-1 alleles in the Hokkaido wheat-breeding program, the effect of Ppd-1 on growth pattern and grain yield should be investigated. Ppd-A1a may be useful as a unique gene source for fine tuning the heading time in the Tohoku-Kyushu region since the effect of Ppd-A1a on photoperiod insensitivity appears to differ from the effect of Ppd-B1a and Ppd-D1a.     

Growth inhibition activities of Sugi bark components against Heterosigma akashiwo

In our ongoing efforts to develop new uses for wood-based waste streams, the growth inhibition activities of extracts obtained from Sugi (Cryptomeria japonica) bark were examined against Heterosigma akashiwo, otherwise known as red tide plankton. The Sugi bark was separated into its outer and inner barks and then extracted sequentially with hexane, ethyl acetate, and methanol. Strong inhibitory activities against H. akashiwo were observed in the tests involving the hexane extract from the inner and outer barks, as well as the ethyl acetate extract from the inner bark. Gas chromatography mass spectroscopy (GC–MS) analysis revealed that cubebol, phyllocladanol, 6,7-dehydroferruginol, ferruginol, and sugiol were the main components in the active extracts. These components themselves were then tested for their growth inhibition activities against H. akashiwo. Cubebol and ferruginol showed potent inhibitory activities, whereas phyllocladanol, 6,7-dehydroferruginol, and sugiol were only weakly active. Taken together, these results suggested that the Sugi bark extracts could be used as inhibition reagents against red tide plankton.     

Relationships between body size and secondary sexual characters,and sperm characters in male Dolly Varden char (Salvelinus malma)

In Salmonidae, subordinate males are exposed to higher risks of sperm competition than dominant males and thus are expected to improve the sperm characteristics (sperm concentrations, sperm velocity and sperm longevity). In this study, we investigated the relationships between body size and secondary sexual characters (breeding colour, hump height and snout length), and sperm characteristics of one‐year‐old (newly matured) Dolly Varden char. Small males displayed higher sperm concentrations than large males. Moreover, males with dull breeding colours, but not with lesser snout length and hump height, displayed an increased sperm velocity compared to males with bright colours, suggesting a trade‐off between sperm quantity and the investment in breeding colour. In addition, sperm longevity decreased as sperm swimming velocity increased. These findings indicate that small males with dull breeding colours improve the quantity and quality of their sperm to a great extent to enhance their chances of reproductive success.     

Impregnation of radiata pine wood by vacuum treatment II: effect of pre-steaming on wood structure and resin content

Radiata pine sapwood and heartwood were dried using high-temperature, conventional-temperature, and air drying schedules with and without pre-steaming. They were then impregnated by vacuum treatment with double-distilled water, toluidine blue, and fluorescein dye. For sapwood, there were only minor differences in uptake between drying methods and when pre-steaming was used. Using microscopy, the primary flow pathways in sapwood were found to be the resin canal network and ray parenchyma cells, which provided conduction without large resistance. In heartwood, uptake was strongly influenced by pre-steaming the green lumber. After pre-steaming heart-wood, there was an increase in uptake from all surfaces but especially from the radial surfaces. Lower extractive contents, disruption of epithelial and ray parenchyma cells, and alteration of the condition of bordered pits were also associated with pre-steaming. It was therefore possible to classify flow paths in radiata pine heartwood five ways, according to uptake values and wood anatomical features.This research was presented in part at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998.     

Embryonic development and morphology of eggs and newly hatched larvae of Pacific herring <Emphasis Type="Italic">Clupea pallasii</Emphasis>

The embryonic development and morphology of eggs and newly hatched larvae of the Pacific herring Clupea pallasii were described using laboratory-reared specimens originating from the Miyako Bay stock. The eggs were almost spherical in shape, 1.33–1.46 mm (mean: 1.38 mm) in diameter, and had a thick adherent chorion. They had a segmented pale yellow yolk, no oil globule, and a relatively wide perivitelline space. A subgerminal cavity was observed during the gastrula period, whereas the blastocoel did not appear. Mass hatching occurred by 271 h 45 min after fertilization, and the newly hatched larvae were 7.1–7.7 mm (mean: 7.5 mm) in total length with 53–56 myomeres at 9.6°C. The embryonic development of Pacific herring was substantially similar to that of zebrafish Danio rerio, American shad Alosa sapidissima, as well as Atlantic herring Clupea harengus, and generally followed the basic developmental pattern of teleosts. However, Pacific herring larvae hatched at a more developed stage than some other clupeoids, such as Japanese sardine Sardinops melanostictus, and the progressed developmental stage at hatching could be interpreted as an advanced adaptation.     

A transdisciplinary research of coastal fisheries co-management: the case of the hairtail <Emphasis Type="Italic">Trichiurus japonicus</Emphasis> trolling line fishery around the Bungo Channel,Japan

Under the coastal fisheries co-management regime in Japan, local fishers play important roles in deciding on and implementing local management measures. Therefore, using the case study of a hairtail trolling line fishery, we conducted a transdisciplinary research with fishers, processors, government officers, etc. Taking social and biological factors into account, we defined management criteria and targets (resource, economic, human community, and local food culture) in collaboration with local fishers. We chartered local fishing vessels to determine parameters that were easily understood by local fishers. We established a local consultative committee comprising fishers, processors, and distributors, and developed a fish distribution strategy to nurture the local hairtail food culture. The integrated effects of various management scenarios were evaluated by the operating model. We found that co-ordinated management by both the trolling line fishery and purse seiners in the neighbouring prefecture was required to achieve targets. Two realistic scenarios are recommended: a conservative scenario that could achieve targets even with few strong year classes, and an adaptive scenario that protects strong year classes, but relies on a higher frequency of these. We shared these results with the local fishers and government officers, which led to actual improvements in management measures.     

Vitamin contents of eggs that produce larvae showing a high survival rate in the Japanese eel Anguilla japonica

This paper describes the relationship between the egg vitamin concentrations and the egg quality in the Japanese eel Anguilla japonica . No notable relation was found between any vitamin and the fertilization rate. Hatching and survival rates of larvae, however, significantly increased with an elevated level of egg vitamin C (VC). In contrast to VC, the relation between vitamins E (VE) and A (VA) concentrations and survival rate showed a clear peak, with a reduced survival rate at both higher and lower vitamin concentrations. The ratio of VE to lipid or highly unsaturated fatty acid (HUFA) in eggs positively correlated with hatching and survival rates of larvae. High-quality (HQ) eggs were determined as eggs that produced larvae having a survival rate higher than 80% at 8 days post hatch, and low-quality (LQ) eggs were determined as eggs that did not hatch. The level of VC of HQ was significantly higher than LQ. The results of this study suggest that HQ eggs, which produce larvae having a high survival rate, must have high levels of VC and VE/HUFA ratio and contain optimum levels of VA and VE in Japanese eel.     

Annual monitoring of growth of red sea bream by multi-stereo-image measurement

Fisheries Science - In aquaculture, periodic measurement of fish body size is required to suitably assess growth progress. The aim of this study is to monitor the growth of free-swimming red sea...     

Characteristics of a self-assembled fibrillar gel prepared from red stingray collagen

A translucent collagen gel was formed from a transparent acidic solution of red stingray collagen by adjusting to physiological ionic strength and pH in phosphate buffer and then incubating at 25–37°C. During fibril formation from red stingray collagen, the turbidity increased when the NaCl concentration was increased at constant pH and the rate of fibril formation was accelerated by higher pH or lower NaCl concentration. The T _m of red stingray collagen fibrillar gel was estimated as 44.3 ± 3.5°C, which was higher than that of the collagen solution, 33.2°C. In addition, red stingray collagen gel maintained its shape without melting and was suitable for culture of mouse stromal cells at 37°C.     

Low-fidelity homing behaviour of Biwa salmon <Emphasis Type="Italic">Oncorhynchus</Emphasis> sp. landlocked in Lake Biwa as inferred from otolith elemental and Sr isotopic compositions

Biwa salmon Oncorhynchus sp. is endemic to Lake Biwa, Japan, where it is an important commercial and recreational fisheries species. However, no information is currently available on its population structure and migration ecology. Therefore, here we evaluated whether otolith Sr/Ca, Ba/Ca and ⁸⁷Sr/⁸⁶Sr ratios can be used as natural signatures in Biwa salmon and then used these to determine the natal origins of lake-migration-phase individuals and spawning adults, and the homing ability of spawning adults in the Lake Biwa water system. Quadratic discriminant function analysis demonstrated that the lake-migration school comprised individuals with multiple origins, including rivers to the east, west and north of Lake Biwa, and that the homing rate of spawning adults was low (18 out of 80 individuals), with ca. 78% of fish straying into non-natal rivers. However, this straying behaviour was not spatially random, with fish tending to migrate upstream in rivers neighbouring their natal rivers. The high rate of straying in spawning adults is considered important for establishing and maintaining this species, which is highly adapted to life in the Lake Biwa water system where environmental disturbances often occur.