Nuclear genome constitution and other characteristics of somatic hybrids between dihaploid Solanum acaule and tetraploid S. tuberosum

Eleven somatic hybrids (2n = 68 to 74) obtained between S. tuberosum ssp. tuberosum cv. Dejima (2n = 48) and ATDH-1 (2n = 24), an anther-culture-derived dihaploid of S. acaule (Yamada et al., 1997), were characterized by nuclear RFLP markers using 49 single-copy DNA probes distributed throughout the potato genome (2 to 6 probes per chromosome). One of the somatic hybrids, DA8-2, had 72 chromosomes and all the Dejima- and ATDH-1-specific markers (124 and 103 bands, respectively), suggesting the presence of a whole set of both parental chromosomes. The other somatic hybrids lost varying numbers of markers up to seventeen. The pattern of the loss of markers indicated the elimination of five chromosomes among four somatic hybrids. A nucleolar organizer region of chromosome 2 was often eliminated in the somatic hybrids. The somatic hybrids studied here had higher frequencies of multivalent formation than the S. tuberosum parent. They had reasonably good seed set when pollinated with S. tuberosum pollen. Hence, homoeologous recombination between S. acaule and S. tuberosum chromosomes is possible and useful traits from S. acaule may be transferred to the S. tuberosum gene pool. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigation of change in tangential strain on the inner bark of the stem and root ofBetula platyphylla var.japonica andAcer mono during sap season

Although it is well known that sap exudation during early spring in temperate deciduous trees occurs in response to daytime warming and nighttime cooling, the mechanisms of the process are not yet fully understood. Previous theories suggested that changes in stress in the wood caused by daytime heating and nighttime cooling might be linked with sap flow. Consequently, a study of itaya-kaede maple (Aver mono) and shirakamba birch (Betula platyphylla var.japonica) looked at tangential strains. One-hour intervals for 3 years of the tangential strains on the inner bark of stem and root were measured in itaya-kaede maple and shirakamba birch during the sap exudation season. The measurements indicated different mechanisms of sap exudation in these two trees. During the sap exudation season in late March, when the temperature fluctuated around 0°C, the tangential strain in the root of itaya-kaede maple showed expansion in the daytime and contraction at night. Conversely, in early April the tangential strain in the root of shirakamba birch exhibited contraction in the daytime and expansion at night. The changes in tangential strains in itaya-kaede maple were attributed to conditioning, a known concept used to explain the uptake mechanism of soil water in maple and its exudation during early spring. However, because the change in tangential strain in the roots of shirakamba birch was similar to that found during the rampant season, sap exudation was not attributed to conditioning but to the plentiful supply of water from the roots. The implications of these mechanisms are that different sap harvesting techniques may be appropriate for different tree species.     

Physicochemical Properties and Molecular Structures of Starches from Millet (Pennisetum typhoides) and Sorghum (Sorghum bicolor L. Moench) Cultivars in Nigeria

Some physicochemical properties and molecular structures of starches from millet (Pennisetum typhoides, Doro and Gero) and sorghum (Sorghum bicolor, red and white) in Nigeria were examined. Starch granules of millet and sorghum were 3–14 μm and 4–26 μm in diameter, respectively. Millet cultivars had similar peak viscosities (204–205 RVU) on pasting, while sorghum showed similar minimum viscosities (155–156 RVU). The actual amylose content (%) calculated from iodine affinity (IA, g/100 g) was 20.1 and 21.4 for sorghum and 21.3 for millet. The IA of amylopectin was high (1.27–1.42) and its average chain lengths were 20–21 with β‐amylolysis limit of 56%. Amylopectins showed a polymodal molecular weight distribution on a molar basis. The distributions differed among the samples with a higher amount of larger molecules in Doro and red sorghum. Weight‐ and molar‐based distributions of debranched amylopectins on HPSEC were polymodal with weight‐based distribution showing presence of long chains. Peak DP values for A+B₁ and B₂+B₃ chain fractions were 13–16 and 42–43, respectively. The (A+B₁)/(B₂+B₃) ratio on molar basis (9.0–11.5) was similar to maize and rice amylopectins. Peak DP on molar‐based distribution for white sorghum and millet amyloses were similar (490–540) and the DP_n range was narrow (1,060–1,300), but weight‐based distribution profiles differed. The average chain lengths were 260–270 with 3.9–4.8 chains per molecule.     

Compositions of extractive components in the testes and ovaries of various sea urchins: comparisons among species,sexes, and maturational status

Fisheries Science - We investigated the compositions of free amino acids (FAAs), organic acids (OAs), and nucleotides and their related compounds (NAs) in the gonads of edible sea urchins in Japan....     

Whole-body heat transfer coefficient and body temperature change of juvenile Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis> according to growth

Bluefin tuna maintain a higher body temperature than ambient sea water. Body heat is derived mainly from metabolic heat to elevate and maintain regional body temperature that is higher than the ambient, while heat loss is caused by heat transfer throughout the whole body surface and gills. Retention of high body temperature is thought to differ at each growth stage, so that a larger body mass maintains a higher body temperature. We evaluated the whole-body heat transfer coefficient, thermal difference between each tissue and water temperature, and metabolic heat in tissues during swimming of juvenile bluefin tuna as a function of fork length (FL) using a small thermometer and a treadmill-type flow tank. A system for maintaining high body temperature was well developed in fish with FL greater than 20.0 cm. Whole-body heat transfer coefficient was fitted to a −0.695 power of mass. Juvenile bluefin tuna showed a transition speed of 3.0 FL/s at which they switched from aerobic to anaerobic motion.     

Hemolytic suppression roles of taurine in yellowtail Seriola quinqueradiata fed non-fishmeal diet based on soybean protein

ABSTRACT:   To elucidate the hemolytic suppression roles of taurine and the necessity of dietary taurine supplementation in yellowtail Seriola quinqueradiata fed a diet without fishmeal, juvenile fish with an initial body weight of 250 g were fed for 40 weeks in floating net cages on soybean protein diets supplemented with 0, 3.0, 4.5 and 6.0% taurine. Taurine concentration of the experimental diets were 0.03, 33.9, 52.8 and 71.6 mg/g, respectively. On the 21st week, fish fed the taurine unsupplemented diet had inferior growth and feed performances, higher death, and there were incidences of green liver and hemolytic anemia. In this group, hepatic and plasma taurine concentrations, serum osmolality and osmotic tolerance of erythrocytes (EC50 value) were significantly lower, and plasma hydroperoxide concentration was markedly higher than in the taurine supplemented groups. These conditions markedly improved corresponding with the increase of dietary taurine concentration. These results indicate that taurine plays a role in hemolytic suppression through osmoregulation and biomembrane stabilization in fish. In addition, it is suggested that yellowtail requires dietary taurine as an essential nutrition for maintaining physiological condition normally.     

Preparation and characterization of fermented seaweed sauce manufactured from low-quality nori (dried and fresh fronds of <Emphasis Type="Italic">Pyropia yezoensis</Emphasis>)

The present study tested processes to manufacture fermented sauce from low-quality nori (dried and fresh fronds of Pyropia yezoensis). The nori sauce was prepared using three tanks with fresh or dried nori cultured in different conditions. In the present study enzymes were not added for the promotion of the degradation of nori, while in a previous study they were. The supernatants of culture mashes obtained from the three tanks were combined, and this low-quality nori sauce (LNS) was characterized and compared with sauces manufactured from high-quality nori, soy, and fish. The LNS showed low concentrations of total nitrogen compounds (0.20 g/100 ml) and free amino acids, and its taste showed a high sourness score as evaluated by a taste-sensing system. On the other hand, the LNS was rich in polysaccharides, which were observed to be readily degraded to lower molecular weight size sugars by heat treatment. The LNS showed little risk for heavy metal or allergen contamination. The obtained sauce product is expected to be commercially utilized as a component of low allergen-risk sauce products after blending with other seasonings without wheat or soy elements.     

Improved survival and growth performances with stocking density manipulation and shelter availability in bagrid catfish Mystus nemurus (Cuvier & Valenciennes 1840) larvae

Manipulation of stocking densities (10, 20, 30, 40 and 50 larvae L^?1), each with or without the presence of shelter was conducted to determine the effects on survival, cannibalism and growth performances of larval bagrid catfish Mystus nemurus (Valenciennes 1840) from 2 to 14 days after hatching. This study revealed that stocking density significantly affected survival, cannibalism, total length, feed intake, specific growth rate and final weight of bagrid catfish larvae. Significantly higher survival was observed at moderate stocking density of more than 20 but less than 50 larvae L^?1. Survival was significantly low beyond this threshold and was the lowest at 10 larvae L^?1, coincides with the highest cannibalism. Total length, feed intake, specific growth rate and final weight were significantly higher at 10 larvae L^?1. Shelter significantly improved total length and feed intake. No significant effects of stocking density and shelter were observed on the apparent feed conversion ratio and coefficient of variation. There was also no significant interaction between stocking density and shelter in all parameters. This study suggests that bagrid catfish larvae could be cultured at more than 20 but less than 50 larvae L^?1 with the availability of shelter for optimal larviculture condition.     

Spatial and temporal variation in the distribution of juvenile southern bluefin tuna Thunnus maccoyii: implication for precise estimation of recruitment abundance indices

Acoustic tags were used to examine the spatial and temporal distribution of southern bluefin tuna (SBT) in southern Western Australia, which is in a region where fishery-independent acoustic surveys of the recruitment abundance index of SBT have been historically undertaken. We investigated patterns of SBT distribution within and inshore of the acoustic survey area during three summer seasons. Annual differences in distribution patterns were characterized by two distinctive migration pathways. An inshore-migrating pathway was observed in two seasons (2004/2005 and 2006/2007), with a relatively high proportion of tagged SBT (84.5, 65.0%) migrating inshore of the acoustic survey area. The other pathway was concentrated along the shelf (2005/2006 season), with an estimated 63.3% of tagged SBT moving within the survey area. These variable migration patterns may bias the interannual fluctuations in abundance indices. Current survey methods can be modified to include both inshore and continental shelf areas. This contribution shows that the accuracy of acoustic surveys can be improved by including ecological patterns.