Characterization of the quantitatively major collagen in the mantle of oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis>

ABSTRACT:   A quantitatively major collagen was isolated from the pepsin-solubilized collagen preparation of the mantle by differential salt precipitation and phosphocellulose column chromatography, and its constituent α components (α1 and α2) were purified by phosphocellulose column chromatography. The subunits were demonstrated to be genetically distinct from each other by peptide mapping and amino acid analysis. The amino acid composition calculated from those of the α1 and α2 components in 2 : 1 ratio coincided well with that of the major collagen from the mantle. These results suggest that the major collagen in the mantle of the oyster may have a heterotrimer structure (α1)₂α2.     

Comparative study on thermal denaturation modes of myosin in walleye pollack and carp myofibrils as affected by salt concentration

ABSTRACT:   The effect of salt concentration on the thermal denaturation profile of myosin in walleye pollack and carp myofibrils was compared by studying the subfragment-1 (S-1) and rod denaturation rates upon heating. Species-specific denaturation mode observed at 0.1 M KCl was no longer detected when samples were heated above 0.5 M KCl, where S-1 and rod denaturation rates were identical to each other. As the heating of the chymotryptic digest of myofibril formed practically no rod aggregates, S-1 denaturation in a form of myosin was the rate limiting step for rod aggregate formation. As the aggregate formation by rod was remarkably suppressed by lowering the temperature, the free movement of myosin tail upon heating was suggested to play an important role in the rod aggregate formation in a high salt medium.     

Migration of anadromous white-spotted charr <Emphasis Type="Italic">Salvelinus leucomaenis</Emphasis>, as determined by otolith strontium: calcium ratios

ABSTRACT:   The migratory history of anadromous white-spotted charr Salvelinus leucomaenis collected from Japanese coastal waters, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith, by means of wavelength dispersive X-ray spectrometry using an electron microprobe. Otolith Sr concentration or Sr : Ca ratios of anadromous S. leucomaenis , fluctuated strongly along the life history transect in accordance with the migration (habitat) pattern from sea to fresh water. The anadrmous S. leucomaenis showed phase L (low Sr : Ca ratio) from the core to the point 1000–2500 µm distant, averaging 1.3 × 10⁻³ to 2.7 × 10⁻³ and thereafter, the ratios increased sharply, being higher than 5.0 × 10⁻³ to 10.0 × 10⁻³. These findings indicated that otolith Sr : Ca ratios reflected individual life histories, enabling a sea habitat to be identified from a freshwater habitat in this species.     

Evaluation of coral bleaching condition <Emphasis Type="Italic">in situ</Emphasis> using an underwater pulse amplitude modulated fluorometer

ABSTRACT:   Photosynthetic activities of hermatypic corals (28 genera, c . 68 species and c. 92 specimen) were measured in November 2000 at Sekisei lagoon, Okinawa, Japan, using an underwater pulse amplitude modulated fluorometer. Maximum quantum yield (Fv/Fm) ranged from 0.61 to 0.70 and had an average value of 0.664 (standard deviation [SD], 0.0289). Following the measurement of Fv/Fm, quantum yield (Fm'-F)/Fm' at eight-leveled actinic-light intensities were obtained from all specimens. Values of electronic transport rates (ETR) were nearly the same under low photosynthetic active radiation (PAR; µmol quanta/m² per s) condition and varied with increasing PAR. The value of ETR at 100 µmol quanta/m² per s ranged from 21.3 to 30.0 and had an average of 27.8 (SD, 2.09). In August 2001, a coral bleaching event was observed in Sekisei Lagoon. During the event, photosynthetic activities of 21 specimens of eight species (seven genera) were measured. By applying two indicators, Fv/Fm and ETR at 100 µmol quanta/m² per s obtained in August 2000, 18 of 21 specimens were suggested under the bleaching process. In case of Porites lutea , seven colonies were visually evaluated for their condition of bleaching and were found to have two 'normal', three 'slightly bleached' and two 'heavily bleached'. From the density of zooxanthellae, colonies evaluated 'normal' or 'slightly bleached' did not show an apparent difference. However, they were clearly identified by Fm/Fv and ETR at 100 µmol quanta/m² per s.     

Effect of a seaweed mixture on serum lipid level and platelet aggregation in rats

ABSTRACT:   To assess the effect of a seaweed mixture on lipid levels in serum as well as platelet aggregation in rats, Eisenia bicyclis ('Arame'), Hizikia fusiformis ('Hijiki') and Undaria pinnatifida sporophylls ('Mekabu'), all brown seaweeds, and Porphyra yezoensis ('Susabinori'), a red seaweed, were powdered and mixed in a ratio of 45:30:20:5 (w/w). When rats were fed a cholesterol-rich diet containing this mixture of seaweeds (9–10% w/w) for 28 days, serum total cholesterol, LDL-cholesterol, free cholesterol, and triglyceride levels declined significantly to 49.7%, 48.1%, 49.0% and 74.8%, respectively, of those of the control. Serum HDL-cholesterol, however, was unchanged. Though activated partial thromboplatin time, prothrombin time, antithrombin III activity, and fibrinogen levels in plasma were unchanged, the maximal ADP- and collagen-induced platelet aggregation decreased significantly to 89.0% and 85.5% control levels, respectively. These results indicate that this mixture of E. bicyclis , H. fusiformis , U. pinnatifida sporophylls, and P. yezoensis , is useful for the prevention of hyperlipidemia and thrombosis in rats.     

基于多年MODIS NDVI 分级的河北平原农田生产力评价

根据中等分辨率航天成像光谱仪(MODIS)遥感数据计算的归一化植被指数(NDVI)被广泛用于作物长势监测和产量预报, 但由于NDVI 数值在不同年份的同一时期变化较大, 直接用于评价农田生产力会有较大误差。本文以河北平原所在的北纬37°~39°之间连续种植的冬小麦农田为研究区域, 通过对多年冬小麦MODISNDVI 数据进行比较和分级, 尝试用每季NDVI 在区域内的高低级别评估区域农田生产力。Landsat 卫星数据用于对不同时相MODIS 图像进行精确配准, 从而实现像素尺度上长时间序列数据的统计分析。首先, 对区域内2000~2008 年间每年作物返青期到成熟期的NDVI 平均值及各生育阶段NDVI 平均值分别进行高低分级, 以了解河北平原农田生产力的空间变异, 结果显示其中高水平农田分布在太行山山前平原, 指数等级水平并没有完全按南北走向趋势分布, 表明该研究方法受纬度差异的影响较小。不同年份分析结果显示, 2008 年东部地区也出现了较高等级的田块。其次, 利用NDVI 分级结果计算出9 年间NDVI 等级的变异系数, 对采用不同生育期NDVI 可能带来的误差进行了分析, 结果显示不同小麦生育期NDVI 等级的变异系数不同, 返青期和成熟期变异系数较大, 且具有一定的地理差异。最后, 利用GIS 空间分析方法以9 年NDVI 分级结果为基础制作了以县为单元的麦田生产力等级图, 结果显示河北平原农田生产力高低分区, 同时也表明中低水平区块有较大提升空间, 为河北县级土地管理和耕地质量管理提供理论依据。     

Long-term changes in land use impact the accumulation of microbial residues in the particle-size fractions of a Mollisol

To test the impact of a range of long-term land use types on the partitioning of microbial residues among soil particles, samples from a Mollisol with plots under 100 years of continuous arable cropping, 30 years of simulated overgrazing to severely degraded bare soil, or 30 years of grassland restoration were investigated. The microbial residues, which were assessed among three particle-size fractions (<2, 2–20, and 20–250 μm) by amino sugar extraction, exhibited change with particle size and land use. Converting arable cropping to bare soil induced substantial depletion of amino sugars associated with the clay-size fraction, as a proportion of total carbon (C) and total soil mass, but not the silt- and sand-size fractions. Alternatively, switching arable soil to grassland increased amino sugar stocks in both the clay- and sand-size fractions. Analysis of the relative input of fungal and bacterial derived amino sugars indicated that fungal sources are the most dynamic with respect to land use change. These results highlight the selective vulnerability of microbial C pools in finer fractions under low plant C input and the selective recovery in specific fractions upon restoration, emphasizing the importance of the conversion of plant organic matter into mineral-associated microbial residues to promote stable soil organic C.     

Are Primary Cultures of Trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) Ventricular Cardiomyocytes Metabolically Viable?

The objectives of this study were to establish a protocol for the isolation of metabolically viable ventricular cardiomyocytes from the rainbow trout and to determine which measures may best reflect viability 24 h after isolation. Cardiomyocytes were isolated by enzymatic digestion and maintained in cell suspension. Viability was assessed using Trypan blue dye exclusion, ATP content, oxygen consumption and lactate dehydrogenase (LDH) leakage into the medium. Viability, assessed by these measures did not significantly change over the time period of this study. ATP content did correlate significantly with oxygen consumption but not with Trypan blue exclusion. We conclude that primary cultured cardiomyocytes remain metabolically viable for at least 24 h after isolation. Also, it appears that ATP content and oxygen consumption most adequately reflect metabolic cell viability. To be confident with a culture, however, a combination of viability measures is necessary when isolating cardiomyocytes from fish.     

Effects of photoperiod on gonadotropin-releasing hormone levels in the brain and pituitary of underyearling male barfin flounder

ABSTRACT:   A pleuronectiform fish, the barfin flounder Verasper moseri , expresses three gonadotropin-releasing hormone (GnRH) forms in the brain: salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II) and seabream GnRH (sbGnRH). To clarify the effects of photoperiod on GnRH systems, changes in brain and pituitary GnRH peptide levels were examined using time-resolved fluoroimmunoassays. In experiment 1, 5-month-old male barfin flounder (mean total length 9.0 cm, body weight 11.0 g) were divided into short (8:16 h light : dark [L:D] cycle; lights on 08.00–16.00 hours) and long photoperiod (16:8 h L:D cycle; lights on 04.00–20.00 hours) groups in mid September and maintained until November under natural water temperature (19.3–15.2°C). Brain sGnRH concentrations were significantly higher in the 16:8 h L:D group than in the 8:16 h L:D group, whereas no significant differences were observed in total length, body weight, plasma testosterone concentration, brain cGnRH-II concentration and pituitary sbGnRH content. In experiment 2, 7-month-old male barfin flounder (mean total length 16.5 cm, body weight 76.8 g) were divided into short and long photoperiod groups in mid December and maintained until February under natural water temperature (12.5–6.6°C). Total length, body weight and condition factor were significantly greater in the 16:8 h L:D group than in the 8:16 h L:D group, whereas no significant differences were observed in plasma testosterone concentration and GnRH levels in the brain and pituitary. These results indicate that levels of sGnRH in barfin flounder are influenced by photoperiodic treatment dependent on water temperature and/or body size.