Effective Method to the Renormalized Finite Quantity of the Meson Loop Propagator (I)

By using the Lorentz invariable coupling model of interaction between neutral meson and nucleon (antinucleon), Feynman convergence integral method is often used to deal with the finite quantity of one-loop correction scheme. On the basis of analyzing, discussing and researching the method, a new method is found. That is the large momentum integral limitation method. With the effective method, we obtain the integral convergence formulation for the finite quantity, by deducting-dimensionally calculating the finite quantity gained after renormalizing the meson loop propagator.     

低温和镁胁迫对黄瓜幼苗生长和生理特性的影响

利用人工气候箱,采用珍珠岩培养,研究不同温度下镁对黄瓜幼苗生长、碳氮代谢和活性氧清除系统的影响。结果表明,低温下,镁胁迫降低了黄瓜的总叶片数、叶面积、根长、全株干质量和壮苗指数,增大了根冠比。适温下,镁胁迫使黄瓜叶片可溶性蛋白、还原糖和可溶性总糖含量、硝酸还原酶活性下降,根系活力提高;低温下,各处理硝酸还原酶活性、根系活力、可溶性总糖含量较对照降低,还原糖含量较对照升高,多镁和适镁使可溶性蛋白的含量较对照降低,缺镁则使其含量较对照提高。多镁和缺镁均导致黄瓜幼苗叶片MDA、H2O2含量及O2 产生速率升高,缺镁升幅大于多镁。低温缺镁对植株的伤害最大,可能与活性氧的增加有关。适温下,镁胁迫使POD、SOD活性升高,其中POD活性升高幅度最大,而CAT活性降低;适温下植株可能主要通过提高POD活性来抵御镁胁迫。     

鱼类镁营养生理的研究进展

镁在动物生理中发挥重要的作用,是动物体内众多酶系的辅助因子和激活剂,也是骨骼和牙齿的重要组成部分。该文就鱼类对镁的需要量及镁与鱼类生长、离子代谢、免疫、抗应激以及渗透压调节等方面的研究进行综述。     

Effect of feeding increasing quantities of starch on glycaemic and insulinaemic responses in healthy horses

The aim of this study was to investigate the effect of increasing the intake of starch on the glycaemic and insulinaemic responses of horses. A cross-over study design was used in which four horses were fed increasing amounts of a compound feed (0.5–3.5 kg) to provide 0.3, 0.6, 0.8, 1.1, 1.4 and 2 g starch/kg bodyweight (BW)/meal. The glycaemic response increased with starch intake (P < 0.05), while feeding <1.1 g starch/kg BW resulted in a lowered response, compared to when 1.1–2 g starch/kg BW was fed (P < 0.01). The results suggested that insulin responses may be more appropriate to define the effect of feeding different starch levels than glycaemic responses. A starch intake of <1.1 g/kg BW/meal produced only moderate glucose and insulin responses, even though highly processed cereals were used. It is therefore recommended that a starch intake of <1.1 g/kg BW/meal or a meal size of 0.3 kg/100 kg BW (starch content of 30–40%) is used for horses.     

土壤水分胁迫对杜仲叶片光合及水分利用特征的影响

通过实验研究了华北石质山区4种不同土壤水分条件下3a生杜仲苗木叶片光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)、气孔限制值(Ls)、水分利用效率(WUE)等参数的光响应过程。结果表明:(1)杜仲叶片在土壤水分轻度(W1)、中度(W2)和重度(W3)胁迫条件下的光饱和点分别比对照(CK)下降12.5%、44.8%、68.5%,晴天日光合速率最大值分别比对照(CK)下降21.5%、47%、69.7%;(2)叶片蒸腾速率(Tr)呈现随光合有效辐射(PAR)增加而上升的趋势。对比CK,Tr在W1、W2和W3条件下分别下降了17%、52%和93%;(3)Gs随着PAR的增加而逐渐上升。对比CK,Gs在W1、W2和W3条件下分别下降了22.6%、67.9%、88.7%。从无水分胁迫一直到中度水分胁迫条件下,气孔限制是影响光合作用的主要原因,而土壤水分严重胁迫条件下,当PAR小于1000μmol.m-2.s-1时,气孔限制是影响光合作用的主要原因,尔后转变为非气孔限制;(4)叶片水分利用效率(WUE)对光强的适应范围比较广,W3条件下,WUE值最高。CK、W1、W2条件下,WUE相差不大,对比W3,分别下降68.6%、69.5%、67.3%。     

Phosphorus limitation in a Ferralsol: Impact on microbial activity and cell internal P pools

Soil microorganisms are key regulators of the biogeochemical phosphorus (P) cycle. Microbial P limitation in highly weathered tropical soils has been reported, but whether it affects the cellular P content of indigenous soil microorganisms and its biochemical composition is unknown. We investigated the effect of microbial P limitation by measuring respiration, microbial growth, community composition and P content of microbial cells in a Ferralsol with low amounts of available P as affected by amendments with C substrates with ample nitrogen (CN) with and without extra phosphate (P). Microbial biomass and community composition were quantified by phospholipid fatty acid (PLFA) analyses. Cellular P content and P pools (PLFA, DNA and RNA per cell) were determined after extraction of microbial cells from soil by density gradient centrifugation. The apparent microbial growth rate during exponential increase in respiration rates in response to CNP addition was 0.072 h⁻¹, compared to 0.017 h⁻¹ for the CN amendment (no extra P added). This suggests that the microbial growth after a combined C and N addition was retarded by P limitation in the native soil (without added P). The net increase in microbial biomass, however, reached similar levels for both the CN and CNP treatment (measured at the point in time when respiration rates peaked). This outcome was unexpected since maximum respiration rates were about three times higher in the CNP compared to the CN treatment. Total P in extracted cells ranged from 2.1 to 8.9 fg P cell⁻¹ (microscopic counts), with a tendency for lower values for treatments without C amendments. Only 10-25% of the measured total P in extracted cells was accounted for by the measured RNA, DNA and PLFA. This low percentage could partly be due to underestimation of the RNA pool (degradation during extraction). PLFA analyses showed that substrate induced growth, regardless of P addition, led to a change in microbial community composition and was dominated by fungi. The extraction of microbial cells from soil by density gradient centrifugation, however, discriminates against fungi. Accordingly, the extracted cells were not fully representative for the entire soil microbiota regarding the community composition and metabolic state. Nevertheless, for the first time microbial cell P content and P pools are reported for microorganisms that actually grew in soil and not in chemostat or batch cultures.     

水分对温室盆栽番茄叶片光响应特性的影响

【目的】探讨水分对番茄叶片光响应特性的影响,为番茄栽培提供科学用水依据。【方法】以番茄品种“金棚1号”为材料,采用盆栽方式,分别按照单株日蒸腾蒸发量（ET）的50%,75%,100%和125%作为补充灌溉量设置4个水分处理,并利用Li-6400XT便携式光合仪测定番茄叶片的光响应曲线。【结果】随着灌溉量的增加,番茄叶片的净光合速率(Pn)、最大光合速率(P_max)、光饱和点(LSP)、蒸腾速率(Tr)、胞间CO₂浓度(Ci)、气孔导度(Gs)均呈现出增加的趋势,其中以125% ET处理的最高;水分利用效率(WUE)、叶片饱和水汽压亏缺（Vpdl）、叶片温度（Tl）、气孔限制值(Ls)则呈下降趋势,其中以50% ET处理的最低;表观量子效率(α)、光补偿点(LCP)则呈先上升后下降的趋势。随着光合有效辐射强度（PAR）的增加,番茄叶片的Pn、Tr、Gs、WUE、Ls均呈先迅速升高后缓慢升高甚至下降的趋势;Ci先急剧下降,后基本保持平稳;Vpdl和Tl先略有下降后逐渐上升。【结论】气孔限制因素是水分影响番茄叶片光合作用的主要因素。按照ET的125%补充灌溉量,可明显提高番茄叶片的Pn,降低WUE。     

Density‐dependent territory size and individual growth rate in juvenile Atlantic salmon (Salmo salar)

Whether territoriality regulates population size depends on the flexibility of territory size, but few studies have quantified territory size over a broad range of densities. While juvenile salmonids in streams exhibit density‐dependent mortality and emigration, consistent with space limitation, there has been relatively little study of how territory size and individual growth rate change over a broad range of densities, particularly in field experiments. Consequently, we manipulated the density (range = 0.25–8 m^?2) of young‐of‐the‐year (YOY) Atlantic salmon (Salmo salar) in mesh enclosures erected in a natural stream to test whether (i) territory size is fixed, decreases continuously or decreases towards an asymptotic minimum size as density increases; and (ii) individual growth rate decreases as a negative power curve with density as in observational field studies. Territory size decreased with increasing density, consistent with an asymptotic minimum size of about 0.13 m² for a 5‐cm fish. Individual growth rate also decreased with density, although the magnitude of decrease was steeper than in observational studies. Our results suggest a limit to how small territories can be compressed, which will set the upper limit to the local density in a habitat. The density‐dependent changes in territory size and individual growth rate will both play a role in the regulation of stream salmonid populations.     

Effects of taurine-magnesium complex on vascular endothelium and hemorheology in rats in vivo

AIM: To study the protective effects of taurine-magnesium complex (TMC) on endothelium and hemorheology in rats. METHODS: A model of the endothelial damage was made by means of giving rats an injection of adrenaline and making them swim in ice-cold water, then number of circulating endothelial cells (CEC) in whole blood, plasma ET-1 and NO₂^-/NO₃^- content, NOS activity and rheology were determined, respectively. The protective effects of TMC were also observed. RESULTS: An increase in the number of CEC accompanied by abnormal whole blood viscosity, and endothelium-derived ET-1 were observed in model rats. Both the NO₂^-/NO₃^- content and NOS activity were declined significantly in model rats. TMC reduced the number of CEC, resumed NO₂^-/NO₃^- content and NOS activity, and improved the whole blood viscosity in a dose-dependent manner in model rats. CONCLUSION: Ice-cold water bath with adrenaline causes an acute damage of vascular endothelium and abnoramal rheology. TMC protects against the injury of vascular endothelium and improves the hemorheology.