Specific dynamic action in two body size groups of the southern catfish (<Emphasis Type="Italic">Silurus meridionalis</Emphasis>) fed diets differing in carbohydrate and lipid contents

Specific dynamic action (SDA), the energy costs associated with meal digestion and assimilation, is generally affected by body size and food composition. We assessed the postprandial metabolic response and calculated SDA in two size groups of the southern catfish (Silurus meridionalis), each fed one of two diets, high lipid or high carbohydrate, at a meal size of 4% the body mass. Using a continuous-flow respirometer, we determined the oxygen consumption rate at 2-h intervals until the postprandial oxygen consumption rate returned to the prefeeding level. None of the parameters (resting metabolic rate, Rpeak, factorial ratio, time-to-peak, duration, energy expended on SDA, or SDA coefficient) were significantly affected by diet nor was there an interaction between diet and body mass. Rpeak and energy expended on SDA for the whole fish body were significantly higher in the larger fish than the smaller one in both dietary treatments, whereas no significant effect of body size was found in mass specific values. Factorial ratio (range 3.41 to 3.60), peak time (range 9.6 to 12.7 h), SDA coefficient (range 9.36 to 10.36%), and SDA duration (range 62.0 to 71.0 h) did not significantly differ between body size groups. These results suggest that in S. meridionalis the percentage of assimilated energy allocated to SDA may be independent of the body mass.     

Evaluation of three phytoplankton species as food for the pearl oyster <Emphasis Type="Italic">Pinctada fucata</Emphasis>

In the pearl cultivation farms of the Ehime Prefecture, Japan, mass mortalities of the pearl oyster Pinctada fucata have occurred since 1994. The occurrences of mass mortality roughly coincided with a shift of the dominant phytoplankton from Skeletonema and Chaetoceros to Chaetoceros and Nitzschia all of which belong to Bacillariophyceae. Hence, we evaluated Nitzschia, together with Chaetoceros and Isocrysis, as food for the oyster. Wet weights, lengths, widths, glycogen contents, and growth rates in terms of wet weight of the oysters in all the feeding treatments were significantly higher than those in the non-feeding treatment. The highest glycogen content (2.34%) and growth rate (2.21 g month⁻¹) were found in the Chaetoceros treatment. Growth rate in the Isocrysis treatment (1.63 g month⁻¹) was also high, although glycogen content in this treatment (0.41%) was low. In the Nitzschia treatment, growth rate of the oyster (0.94 g month⁻¹) was the lowest and glycogen content (0.83%) was also low relative to that in the Chaetoceros treatment. Chlorophyll a concentration in fecal pellets was lowest in the Nitzschia treatment (<2.7 μg mg⁻¹), suggesting more complete digestion of Nitzschia by the oyster. Thus, Nitzschia was edible and digestible but not assimilated by P. fucata. We propose the following scenario for the relationship between Nitzschia dominance and mass mortality. When Nitzschia dominates in a culture area, the physiological condition of P. fucata deteriorates due to low assimilation of Nitzschia by the oyster, followed by susceptibility of the oyster to infection by agents lethal to the oyster.     

The harvest of the freshwater crayfish <Emphasis Type="Italic">Astacus leptodactylus</Emphasis> Eschscholtz in Turkey: harvest history,impact of crayfish plague,and present distribution of harvested populations

This review focuses on the present distribution of populations of the crayfish Astacus leptodactylus that are harvested in Turkey. It also examines the history of this harvest and the impact that crayfish plague has had on them. Crayfish plague, caused by the fungus-like organism, Aphanomyces astaci Schikora, 1906, is a severe parasite of freshwater crayfish and has caused a lot of damage to A. leptodactylus populations in Turkey since 1984. Turkey was the largest provider of A. leptodactylus to Western Europe from 1970 (or possibly earlier) until 1986. For example, the peak production was reached in the early 1980s, with over 5,000 tonnes being exported in 1984. On the other hand, as a result of the crayfish plague the harvest of A. leptodactylus was reduced severely in most populations in Turkey after 1985. The harvest was only 320 tonnes in 1991. After the occurrence of crayfish plague in Turkey, in order to increase crayfish production uncontrolled A. leptodactylus stockings have been carried out in many waterbodies throughout Turkey. These introductions have caused an increase in the number of A. leptodactylus populations, but exploitation of A. leptodactylus is still under the pressure of the plague, although there has been a steady increase in crayfish production in recent years. The harvest increased to 2,317 tonnes in 2004. Fortunately, among those populations affected by crayfish plague, large amounts of A. leptodactylus can still be harvested from three lakes, ?znik (Bursa), E?irdir (Isparta) and Çivril (Denizli). Thus, it seems that A. leptodactylus has a degree of resistance to crayfish plague. It is therefore interesting to investigate the resistance of A. leptodactylus caught from these populations to crayfish plague.     

Transpositional feeding rhythm of loach <Emphasis Type="Italic">Misgurnus anguillicaudatus</Emphasis> from larvae to juveniles and its ontogenesis under artificial rearing conditions

The diel feeding rhythm and ontogenesis during early life stage of loach Misgurnus anguillicaudatus were investigated under experimental conditions (light: L 06:00–18:00, D 18:00–06:00 h). Morphological and behavioral developments of loach from newly hatched to 40 days after hatching were observed. Larvae were able to prey on daphnia 3–4 days after hatching at 23 ± 0.5°C. As the larvae grew, they showed an increasing feeding capacity and a distinct feeding rhythm. Feeding intensity and incidence for day-4 larvae were highest at 10:00 and 16:00 h. The highest levels of feeding intensity for day-12 larvae occurred at 08:00, 12:00, and 18:00 h as did feeding incidence. By day 20, when the larvae metamorphosed, the highest levels of feeding intensity occurred at 06:00, 18:00, and 24:00 h and were concurrent with the highest feeding incidence. After metamorphosis, feeding capacity had again increased considerably and, in contrast to the earlier stages before day 20, feeding intensity for day-30 juveniles peaked at 05:00 and 20:00 h, about 1–2 h after the maximum feeding incidence. The feeding rhythm of loach juveniles at day 40 was almost the same as the day-30 juveniles. The estimated maximum daily feeding rates were 43.1%, 33.4%, 19.0%, 12.8%, and 5.8% of body weight on days 4, 12, 20, 30, and 40, respectively. Thus, loach was found to have different feeding rhythms in the pre- and post-metamorphosis stages, with the highest feeding activity in daytime during the larval planktonic stage before metamorphosis, and intensely nocturnal feeding behavior during the juvenile benthic stage after metamorphosis.     

Classification of Tomicus Species

Both morphological characters and a portion of of 28S rDNA sequences were used to identifying Tomicus species.The specimens were classed into groups with the following characters: 1) granules or punctures on interstria 2 on the declivity of the elytra;2) length of the elytral interstrial hairs and hairs arising from punctures;3) arrangement of pronotal punctures and hairs.These characters could be clearly examined under a binocular microscope at 30×magnification and they were applicable and valuable for the forest entomologists to identify Tomicus species.The phylogenetic tree established with difference in 28S rDNA sequence of D2 region revealed that the specimens of each group identified by morphological characters were also grouped together.The genetic distances of intra-species, inter-species and inter-genus were not overlapped. Genetic divergence of 28S rDNA was also useful for identifying Tomicus species.     

CSR与公司财务绩效相关性研究与展望

对国外CSR与公司财务绩效的相关研究进行了梳理、评述,对研究现状进行了总结,提出了未来的研究展望,从而为我国的CSR研究理清脉络,丰富现有的研究文献,为促进我国公司治理水平的提高提供新的研究角度和有效的建议。     

不同铝水平胁迫对橡胶树幼苗若干生理指标的影响

研究不同铝水平胁迫(0、50、100、200、400 mmol/L)对橡胶树幼苗过氧化物酶(POD)、超氧化物歧化酶(SOD)、丙二醛(MDA)、叶绿素含量、叶片相对电导率及幼苗地上部与地下部铝含量变化的影响。结果表明,铝胁迫均使橡胶树幼苗生理指标产生一定的变化。在200 mmol/L和400 mmol/L铝水平下橡胶苗叶片POD活性和SOD活性先上升后下降至胁迫前甚至为0;MDA含量则大量增加,而且越来越高;叶绿素总量、叶绿素a和叶绿素b随胁迫时间的推移呈下降趋势,且铝浓度越大下降趋势越明显;相对电导率随胁迫时间的推移均呈现上升趋势,介于60%~100%之间,超过细胞质膜死亡的阈值;橡胶苗地下部铝含量分别约为地上部铝含量的3倍、2倍、1.3倍。不同铝水平胁迫处理中,随着铝浓度越高、胁迫时间越长对橡胶树幼苗生理指标的影响越大。其中在200 mmol/L铝水平下叶片相对电导率大于50%,达到叶片细胞膜透性阈值,MDA则大量增加,SOD和POD急速上升后下降,叶绿素含量极少。因而认为橡胶树幼苗的最高铝耐受浓度为200 mmol/L,地下部铝含量的耐受量为6.2 mg/g,地上部的耐受量为2.9 mg/g。     

不同有机酸对大豆生长的化感效应

试验采用发芽试验、水培试验及室内分析相结合的方法研究了经GC－MS检测出的大豆根系分泌物和根茬腐解液中的几种有机酸对大豆种子萌发及幼苗生长发育的化感效应。结果表明：3－硝基邻苯二甲酸、邻甲氧基苯甲酸、3，4－二氯苯甲酸、肉桂酸等四种有机酸均抑制了大豆种子的萌发，表现在萌发率、胚根长和 胚根干重与对照相比均有所降低，差异达显著或极显著水平，而且有机酸浓度不同，抑制程度也有所差别；3－硝基邻苯二甲酸、邻甲氧基苯甲酸、3，4－二氯苯甲酸、肉桂酸、邻苯二甲酸等五种有机酸不同程度地抑制了水培大豆幼苗的生长发育，表现在株高、干物质重、相对生长速率等均低于对照，差异达显著或极显著水平，且随着有机酸浓度的增加，抑制作用增强。     

微生物营养剂对峨眉蔷薇种子萌发的影响

以峨眉蔷薇种子为材料,低温冷藏后取出,利用不同质量浓度的微生物营养剂进行暖温催芽处理,以零添加、零处理为对照,研究探讨了不同碳、氮质量浓度的微生物营养剂对种子萌发的影响,结果显示,不同质量浓度的营养剂均可不同程度地提高种子萌发率,促进种子快速萌发;较适宜营养剂,即蔗糖、酵母膏质量浓度分别为5、1.0g· L-1;质量浓度最高的组合效果最差,较低的碳源、氮源质量浓度组合表现出较好的综合促进作用,推测可能与微生物的活动周期有关,最适的营养剂质量浓度等仍有待进一步研究.     

Six New Diterpene Glycosides from the Soft Coral Lemnalia bournei

A chemical study on the extracts of soft coral Lemnalia bournei resulted in the isolation and identification of six new bicyclic diterpene glycosides including three new lemnaboursides E–G (1–3), and three new lemnadiolboursides A–C (4–6), along with three known lemnaboursides (7–9). Their structures were elucidated by detailed spectroscopic analysis, ECD analysis, chemical methods, and comparison with the literature data. Lemnadiolboursides A–C (4–6) contained a lemnal-1(10)-ene-7,12-diol moiety compared with the lemnaboursides. All these compounds were evaluated for antibacterial activity; cell growth inhibition of A549, Hela, HepG2, and CCRF-CEM cancer cell lines; and inhibition of LPS-induced NO production in RAW264.7 macrophages. The results indicated that compounds 1, 2, and 4–6 exhibited antibacterial activity against Staphylococcus aureus and Bacillus subtilis (MIC 4–16 μg/mL); compounds 1–9 displayed low cytotoxicity on the CCRF-CEM cell lines (IC₅₀ 10.44–27.40 µM); and compounds 1, 2, and 5 showed weak inhibition against LPS-induced NO production (IC₅₀ 21.56–28.06 μM).