温度和个体大小对单齿螺耗氧率和排氨率的影响

采用静水法测定了不同温度、不同个体大小的单齿螺耗氧率和排氨率。结果表明:在16-33℃的实验温度范围内单齿螺的耗氧率(R_O)和排氨率(R_N)与软体部干重(W)都呈负相关,它们之间关系可以分别用幂函数R_O=aW^-b和R_N=a₁W^-b1表示。16～29℃温度范围内单齿螺的耗氧率和排氨率均随温度的升高而增加,29℃时耗氧率和排氨率达到最大值,当温度继续升高超过29℃后,耗氧率和排氨率则随温度的升高而下降,耗氧率、排氨率与温度之间呈显著的指数函数关系R_O=ce^dT和R_N=c₁e^d1T;不同个体大小单齿螺的O:N比在16～20℃时较大,Q₁₀取值范围0.56-3.74,平均值为1.64。方差分析表明,温度、软体部干重对单齿螺的耗氧率和排氨率均有极显著的影响(P<0.01)。     

鲻幼鱼耗氧率、排氨率和窒息点的研究

为探讨鲻幼鱼的耗氧率、排氨率和窒息点,采用封闭流水式实验方法,在不同体质量、光照、放养密度、水流速度以及昼夜更替的条件下,测定鲻幼鱼的耗氧率和排氨率,并且观测体质量对幼鱼窒息点和窒息时间的影响。实验期间水温为19℃±1℃,盐度30,pH7.7。研究结果显示:鲻幼鱼的耗氧率随体质量增加而上升,其变化趋势可用幂函数方程表达:Y=0.4759X0.1878(R2=0.9454);光照对耗氧率的影响较大,对排氨率无明显影响;放养密度对耗氧率的影响差异显著(P0.05),对排氨率的影响差异极显著(P0.01);幼鱼的呼吸代谢旺盛时段在中午11∶00至夜间23∶00;流速对耗氧率和排氨率的影响差异均极显著(P0.01);不同体质量幼鱼窒息点和窒息时间的差异极显著(P0.01)。     

环境因子对卵形鲳鲹幼鱼耗氧率和排氨率的影响

运用封闭流水式实验方法研究温度、盐度、pH和流速对卵形鲳鲹(Trachinotus ovatus)幼鱼耗氧率和排氨率的影响.实验结果表明,随着温度的升高,耗氧率和排氨率均是先增大后减小,当温度为27℃时,耗氧率和排氨率达最大值,温度对卵形鲳鲹幼鱼耗氧率和排氨率的影响显著(P＜0.0l);耗氧率和排氨率随着盐度的升高均出...     

体质量和水温对太湖秀丽白虾人工驯养子代耗氧率和排氨率的影响

以太湖秀丽白虾(Exopalaemon modestus)人工驯养子代为实验样本,实验共设置6个体质量梯度及7个温度梯度,样本体质量范围为(0.12±0.01)～(1.93±0.05)g,实验温度范围为12℃～30℃,研究了体质量及水温对耗氧率和排氨率的影响。结果表明:秀丽白虾耗氧率变幅为0.1497～0.9053mg·g-1·h-1,均值为0.3901mg·g-1·h-1;排氨率变幅为0.0165～0.0866mg·g-1·h-1,均值为0.0379mg·g-1·h-1。体质量、水温及两者的交互效应均对耗氧率和排氨率具有极显著的影响(P0.01)。体质量与耗氧率和排氨率之间的回归关系分别符合幂函数方程Ro=0.3114W-0.2414(r=-0.436)和Rn=0.0307W-0.3007(r=-0.653);水温与耗氧率和排氨率之间的回归关系分别符合指数方程Ro=0.0711e0.0749t(r=0.877)和Rn=0.0113e0.0530t(r=0.747);体质量、水温与耗氧率及排氨率的二元回归方程分别为Ro=0.028T-0.147W-0.053(r=0.948)和Rn=0.002T-0.017W+0.013(r=0.922)。耗氧率和排氨率Q10变幅分别为1.17～4.20和1.15～2.29,均值分别为2.10和1.64。在实验温度范围内,氧氮比均随着水温的上升而增大,变幅为7.42～13.62,均值为10.04。秀丽白虾在低温阶段(12℃～18℃)主要以蛋白质为供能物质,在高温阶段(21℃～30℃)对脂肪的利用有所增加,中等规格个体的脂肪代谢率最高。     

温度和盐度突变对菲律宾蛤仔斑马蛤耗氧率和排氨率的影响

为研究温度和盐度对蛤仔新品种斑马蛤耗氧排氨的影响,以野生蛤仔为对照,实验设置15、20、25、30和35℃五个温度梯度和20、25、30、35和40五个盐度梯度,结果表明:温度和盐度对斑马蛤的耗氧率和排氨率影响显著（P < 0.05）。在温度15-35℃内,随着温度的增加,耗氧率和排氨率整体上呈增加的趋势。在20-40盐度内,耗氧率随着盐度的升高先减少后增加,排氨率随着盐度的升高先增加后减少,在盐度为30时达到最高值。在水温为15℃,盐度20-40内,斑马蛤的O:N为9.534-62.008;在盐度为35,水温在15-35℃内,斑马蛤的O:N是20.700-74.138。与野生蛤仔比较,斑马蛤的耐高温能力要强于野生蛤仔,从Q₁₀的变化反映出斑马蛤对温度的敏感性相对较弱,适应温度变化的能力比较强;斑马蛤的耐低盐和耐高盐能力强于野生蛤仔。研究结果为进一步完善蛤仔斑马蛤的人工养殖技术提供参考。     

盐度和温度对不同规格虎斑乌贼幼体的耗氧率、排氨率和窒息点的影响

为探究体重、盐度和温度对不同规格的虎斑乌贼(Sepia pharaonis)幼体耗氧率、排氨率以及其窒息点的影响。采用单因子试验设计和密闭静水法, 对不同体重下(0.212、0.385、0.476、0.597、0.754和0.946 g)虎斑乌贼幼体的耗氧率和排氨率, 以及不同体重(0.476、0.673、1.341、3.873和4.205 g)幼体的窒息点进行了测定, 同时研究了不同盐度(19‰、22‰、25‰、28‰和31‰)和温度(18、21、24、27和30℃)对不同规格[A: 体重(0.366±0.042) g, B: 体重(0.556±0.038) g, C: 体重(0.844±0.051) g]的虎斑乌贼幼体耗氧率(R_O)和排氨率(R_N)的影响。结果表明: (1)虎斑乌贼幼体体重对耗氧率和排氨率均影响显著(P<0.05)。随着幼体体重的增长, 耗氧率和排氨率显著下降, 个体越小耗氧率和排氨率越大; (2)盐度对幼体的耗氧率和排氨率有显著影响(P<0.05), 均随着盐度的增加呈先下降后上升的趋势, 其中, A规格和B规格的幼体在盐度25‰时, 耗氧率和排氨率显著低于盐度19‰、22‰和31‰时的3个试验组(P<0.05), 而与盐度28‰时无显著差异(P>0.05); C规格幼体的耗氧率在盐度28‰时显著低于盐度19‰组(P<0.05), 而排氨率在盐度25‰时显著低于盐度19‰和31‰两组(P<0.05)。盐度对A规格幼体的氧氮比(O/N)值有显著影响(P<0.05), 而对B规格和C规格的幼体无显著影响(P>0.05)。(3)温度对不同规格幼体的耗氧率和排氨率有显著影响(P<0.05), 均随温度的增长, 呈先上升后下降的趋势。其中, A规格和C规格幼体的耗氧率在27℃时, 显著高于18和30℃两组(P<0.05), B规格的在水温24℃时显著高于18和30℃(P<0.05); A规格和B规格幼体的排氨率分别在24和27℃时, 显著高于其他温度组(P<0.05), C规格的在温度27℃时, 显著高于18和30℃两组(P<0.05); 温度对A规格幼体的O/N值有显著影响(P<0.05), 而对B规格和C规格的幼体无显著影响(P>0.05)。(4)虎斑乌贼幼体的窒息点为0.84—1.62 mg/L, 随着体重的增加而逐渐降低。     

温度对黑鱾幼鱼耗氧率和排氨率的影响

本文研究了温度对饱食和饥饿状态下黑纪(Girella melanichthys)幼鱼耗氧率和排氨率的影响.结果表明:在温度为15～30℃范围内,黑纪幼鱼在饱食状态下的耗氧率、饥饿状态下的耗氧率、饱食状态下的排氨率和摄食率均随温度的升高而增加(P＜0.01),30℃时达到最大,温度为32℃时,均下降;在温度为15～32℃范围内,黑鱾幼鱼在饥饿状态下的排氨率随温度升高而增加(P＜0.01),32℃时达到最大.多项指标表明黑纪幼鱼生长适温在30℃左右.     

长期饥饿下熊本牡蛎生理代谢和酶活性变化

为了探讨熊本牡蛎(Crassostrea sikamea)在长期饥饿胁迫下的生理代谢响应，测定了长期饥饿(0～80 d)以及再投喂(90～118 d)状态下熊本牡蛎的耗氧率、排氨率以及肝胰腺组织乳酸脱氢酶、琥珀酸脱氢酶、丙酮酸激酶、超氧化物歧化酶、碱性磷酸酶和溶菌酶的活性。结果表明：长期饥饿下，熊本牡蛎的耗氧率和排氨率极显著降低(P<0.01);随着饥饿时间的延长，熊本牡蛎乳酸脱氢酶、琥珀酸脱氢酶、丙酮酸激酶、超氧化物歧化酶和碱性磷酸酶活性均呈现波动下降的趋势，溶菌酶活性呈现波动上升的趋势；再投喂后熊本牡蛎的耗氧率、排氨率均极显著升高(P<0.01);长期饥饿对熊本牡蛎代谢和免疫功能造成损伤，熊本牡蛎通过降低代谢率和代谢酶的活性应对长期饥饿胁迫。本研究可为海水贝类饥饿胁迫下代谢调节机制的研究提供参考。     

卵形鲳鲹幼鱼耗氧率和排氨率的初步研究

运用封闭流水式实验方法对不同体重和放养密度的卵形鲳鲹(Trachinoms ovatus)幼鱼耗氧率和排氨率进行了初步的研究。结果表明,卵形鲳鲹幼鱼的耗氧率随着鱼体重的增加而逐渐下降,排氨率总体上也呈降低的趋势,体重对卵形鲳鲹耗氧率、排氨率的影响均达到显著水平(P0.05);光照对卵形鲳鲹幼鱼的耗氧率和排氨率影响非常显著(P0.01),幼鱼在遮光条件下的耗氧率和排氨率分别比在自然光照条件下要低25.18%～40.76%和16.28%～40.28%;随着放养密度的增加,卵形鲳鲹幼鱼的耗氧率逐渐降低,排氨率随着密度的增加呈先上升后下降的趋势,放养密度对卵形鲳鲹耗氧率、排氨率的影响均达到显著水平(P0.05)。卵形鲳鲹的耗氧率和排氨率具有明显的昼夜变化,白天的耗氧率和排氨率均高于夜间值,耗氧率的低谷值为高峰值的69.68%,排氨率的低谷值为高峰值的30.91%。卵形鲳鲹幼鱼的窒息点溶解氧含量为(0.991±0.058)mg/L。     

温度、盐度对强壮箭虫耗氧率和窒息点的影响

研究了不同温度、盐度下强壮箭虫的耗氧率和窒息点.结果表明:温度和盐度均对强壮箭虫的耗氧率和比耗氧率有显著影响.试验温度在5℃-25℃,强壮箭虫个体耗氧率(IO)和比耗氧率(SO)开始随温度的升高而升高,之后呈明显下降趋势.其回归方程分别为y=0.0058x3 -0.2956x2+4.415x-8.7816(R2=0.99,P＜0.05)和y=0.0011x3 -0.0546x2+0.8161x-1.6232(R2=0.99,P＜0.05),数值分别为6.30～11.71μg·ind-1·h-1和1.22 ～2.16μg· mg-1·h-1,窒息点为4.18～6.87 mg·L-1.盐度10 ～40条件下,IO和SO随盐度的升高逐渐下降,回归方程分别为y=-0.0068x2 -0.1412x+21.702(R2=0.89,P＜0.05)和y=-0.0013x2-0.0261x+4.0114( R2 =0.89,P＜0.05),数值分别为4.98～17.73μg ·ind-1·h-1和0.92～3.56 μg·mg-1 ·h-1,窒息点为4.02～6.24 mg·L-1.对强壮箭虫与其他水生动物的耗氧率和窒息点进行比较得出,强壮箭虫是一种狭氧性浮游动物.     

The cryopreservation of Chlorella 1. Interactions of rate of cooling,protective additive and warming rate

The cryoprotective additives glycerol and dimethylsulphoxide were found to be toxic to Chlorella cells at concentrations greater then 2.5% w/v. Polyvinylpyrrolidone, was not damaging up to a concentration of 15% w/v. Chlorella 211/7a had a recovery rate greater than 95% at all rates of cooling studied. With Chlorella 211/8h the survival was lower than 0.1% at all rates examined. The addition of dimethylsulphoxide (5% w/v) to Chlorella 211/8h increased the recovery, particularly at the faster rates of cooling; with polyvinylpyrrolidone (10% w/v) there was an optimum range of cooling rate.Cells of Chlorella 211/7a from the exponential phase of growth were found to be damaged both by a temperature reduction from 25°C to 0°C (thermal shock) and by freezing and thawing. In contrast cells from the stationary phase of growth were resistant to these stresses.Abbreviations DMSO dimethylsulphoxide - HEPES N-2-hydroxyethylpiperazine-N-2-ethansulphonic acid - PVP polyvinylpyrrolidone     

Dietary alterations in protein,carbohydrates and fat increase liver protein-turnover rate and decrease overall growth rate in the rainbow trout (Oncorhynchus mykiss

We have determined the protein-turnover rates and nucleic-acid concentrations in the liver of trout (Oncorhynchus mykiss) fed on two different isocaloric diets: low-protein/high-fat and non-carbohydrate/high-fat. Compared to controls, the partial replacement of protein with fat significantly decreased the protein accumulation rate and protein-retention efficiency in the liver whilst increasing the fractional protein-synthesis and protein-degradation rates as well as protein-synthesis efficiency. The complete replacement of carbohydrates with fat significantly lowered the protein-accumulation rate and protein-retention efficiency, but enhanced both the protein-synthesis and protein-degradation rates as well as protein-synthesis capacity. The protein:DNA and RNA:DNA ratios decreased considerably on both diets. Total DNA decreased in fish on a low-protein/high-fat diet but did not change in those on a non-carbohydrate/high-fat diet. The absolute protein-synthesis rate registered no significant change under any of the nutritional conditions. Both the experimental diets did however raise the fractional protein-synthesis rate significantly, due to enhanced protein-synthesis efficiency when protein was partially replaced with fat and to enhanced protein-synthesis capacity when carbohydrates were completely replaced with fat. Our results show the capacity of the liver to adapt its turnover rates and conform to different nutritional conditions. They also point to the possibility of controlling fish growth by dietary means.     

Control of relative growth rate by application of the relative addition rate technique to a traditional solution culture system

The relative addition rate (RAR) technique allows the nutritional control of plant relative growth rate (RGR) by the provision of nutrients at exponential supply rates. The technique, however, was developed with technologically sophisticated aeroponic systems. In this paper, we report on experiments used to adapt the RAR technique to a conventional solution culture system. A background concentration requirement of 36 μM nitrogen (N), with other nutrients supplied in proportion to N, was necessary to produce a constant RGR of Triticum aestivum L. (wheat) at a low RAR. Solution pH changes were reduced by increasing the percentage of NH₄ in the nitrogen supply, but the plants exhibited dry weight reductions and symptoms of toxicity above 30% NH₄. For wheat, a ratio of 25/75 NH₄/NO₃ was optimum for minimizing pH changes within the nontoxic range. A test of the effectiveness of the RAR technique using this background concentration and NH₄/NO₃ ratio showed that RGR increased with RAR with a linear slope of 0.55 and an intercept of 0.07 d^-1. Although the relationship between growth rate and nutrient supply was less than the one-to-one dependence of RGR on RAR that has been obtained with more sophisticated apparatus, application of the RAR technique to a conventional solution culture system still affords considerable control of RGR and presents a simple method for growing plants at different levels of nutrient stress and at distinct RGRs.     

Effect of temperature on development rate and intrinsic rate of increase ofAphis gossypii reared on greenhouse cucumbers

Thermal requirements for development and life table statistics ofAphis gossypii Glover (Homoptera, Aphididae) were determined over a range of constant temperatures from 10 to 30°C. The lower development threshold and the sum of effective temperatures were 6.9°C and 90.1°C, respectively, for preimaginal development, and 5.8°C and 113.6°C from birth to the onset of reproduction. Mean total fecundity ranged from 36 larvae per female at 10°C to 76 larvae at 30°C. On a time scale of days, net reproductive rate (R _o ) increased with increasing temperature while generation time (T) decreased causing the intrinsic rate of increase (r _m ) to increase linearly from 0.115 to 0.465. On a day-degree scaler _m only varied from 0.019 to 0.028 because the growth ofR _o was compensated by an increase inT with increase in temperature. The nearly constantr _m in terms of day-degrees, over a wide range of temperatures, greatly simplifies the prediction of future population numbers ofA. gossypii.     

Environmental variation for outcrossing rate in rapeseed (Brassica napus)

Summary Rapeseed (Brassica napus) is a predominantly selfpollinated crop with about one-third outcrossing. The outcrossing rate may be influenced by environmental factors, and hence changes in the heterozygosity level of a variety may occur during multiplication. In an investigation on environmental variation in outcrossing, we estimated the outcrossing rate in the Swedish spring rapeseed cv Topas by isozyme analysis and found that outcrossing varied from 12% to 47% over five locations in Sweden, Denmark and Germany. Among flowers at different positions on the same plant, average outcrossing varied from 11% at the top to 39% at the bottom of the plant. In conclusion, environmental factors can greatly influence the outcrossing rate in rapeseed, and an investigation therefore merit further studies.     

Reduction of metabolic rate and thermoregulation during daily torpor

Physiological mechanisms causing reduction of metabolic rate during torpor in heterothermic endotherms are controversial. The original view that metabolic rate is reduced below the basal metabolic rate because the lowered body temperature reduces tissue metabolism has been challenged by a recent hypothesis which claims that metabolic rate during torpor is actively downregulated and is a function of the differential between body temperature and ambient temperature, rather than body temperature per se. In the present study, both the steady-state metabolic rate and body temperature of torpid stripe-faced dunnarts, Sminthopsis macroura (Dasyuridae: Marsupialia), showed two clearly different phases in response to change of air temperature. At air temperatures between 14 and 30°C, metabolic rate and body temperature decreased with air temperature, and metabolic rate showed an exponential relationship with body temperature (r ²=0.74). The Q ₁₀ for metabolic rate was between 2 and 3 over the body temperature range of 16 to 32°C. The difference between body temperature and air temperature over this temperature range did not change significantly, and the metabolic rate was not related to the difference between body temperature and air temperature (P=0.35). However, the apparent conductance decreased with air temperature. At air temperatures below 14°C, metabolic rate increased linearly with the decrease of air temperature (r ²=0.58) and body temperature was maintained above 16°C, largely independent of air temperature. Over this air temperature range, metabolic rate was positively correlated with the difference between body temperature and air temperature (r ²=0.61). Nevertheless, the Q ₁₀ for metabolic rate between normothermic and torpid thermoregulating animals at the same air temperature was also in the range of 2–3. These results suggest that over the air temperature range in which body temperature of S. macroura was not metabolically defended, metabolic rate during daily torpor was largely a function of body temperature. At air temperatures below 14°C, at which the torpid animals showed an increase of metabolic rate to regulate body temperature, the negative relationship between metabolic rate and air temperature was a function of the differential between body temperature and air temperature as during normothermia. However, even in thermoregulating animals, the reduction of metabolic rate from normothermia to torpor at a given air temperature can also be explained by temperature effects.Abbreviations BM body mass - BMR basal metabolic rate - C apparent conductance - MR metabolic rate - RMR resting metabolic rate - RQ respiratory quotient - T _a air temperature - T _b body temperature - T _lc lower critical temperature - T _tc critical air temperature during torpor - TMR metabolic rate during torpor - TNZ thermoneutral zone - T difference between body temperature and air temperature - VO₂ rate of oxygen consumption     

Photosynthetic rate and yield formation in different maize hybrids

The relationship between photosynthetic rate and yield formation processes of the newer and older maize hybrids were investigated. Leaf area at flowering (source) and kernel number (sink) of the newer hybrids were greater than the older ones although their light-saturated photosynthetic rate (P_sat) were not greater than the older ones before flowering. After flowering, P_sat and chlorophyll content of the newer hybrids declined more slowly than the older ones. They not only distributed almost all photosynthates produced after flowering to grain but also reallocated some reserved photosynthates produced before flowering to grain. The newer hybrids exhibited greater grain mass than the older ones mostly because they could optimally regulate the photosynthetic rate and yield formation processes to maximize grain mass.     

Light quality growth promotion of Spiraea nipponica: the influence of a low photon fluence rate and transfer time to a higher fluence rate

Combinations of different light quality and fluence exposure times were investigated for their effects on in vitro growth of the woody plant Spiraea nipponica. An interaction was demonstrated between different levels of benzyladenine (BA) used for in vitro propagation and the specific light regimes investigated. This relationship was affected by the length of exposure to either white or red/FR light and the time of transfer from one fluence rate to another. In all instances exposure to red/FR light resulted in more extensive growth than under white light. Thus explants cultured under 0.25 and 0.4 mg l^-1 of BA exhibited high shoot proliferation rates when transferred, after 4 weeks of low photon fluence red/FR light, to higher fluence white light for a further week. The proliferation rates obtained were higher than any white light treatment including that with the highest BA level of 0.5 mg l^-1. In addition, the combination of red/FR light exposure with a white light stage of higher fluence improved proliferation at lower exogenous BA levels.     

Ethanol evolution rate: a new parameter to determine the feeding rate for the production of avermectins by Streptomyces avermitilis

A new parameter ethanol evolution rate (EER) was developed to aid in the determination of glucose feeding rate in avermectin production. The EER characterized the level of primary metabolism and its value was affected mainly by the supply of O2 and glucose. In an abnormal batch, over-feeding of glucose led to 2.5-fold increase of the maximum EER value compared to the normal one, and the production was thus decreased by nearly 80%. Together with other criteria, the EER helped to control utilization of substrate, so it has been successfully used to control glucose feeding in an industrial process.     

Net reproductive rate of unmanaged honeybee colonies, (Apis mellifera L.)

Summary The net reproductive rate of unmanaged honeybee colonies has never been fully determined for honey bees in temperate climates. In this study, five overwintered colonies in Kansas, USA, were allowed to swarm naturally (Winston. 1980). These colonies and their swarms were studied over the winter (i.e. one generation). The net reproductive rateR ₀ was estimated to be 2.18. Afterswarms were found to contribute substantially (41.2%) to this net reproductive rate. The autumn and spring food reserves and brood areas of established colonies and colonies established from prime swarms and afterswarms are compared. Winter survival of afterswarms was related to autumn honey stores, and the brood areas of surviving afterswarms were smaller than those of prime swarms or established colonies.