药隔期低温胁迫对小麦干物质积累、转运和分配及产量的影响

为探明药隔期低温胁迫对小麦产量的影响,以烟农19、新麦26为供试材料,在小麦药隔期进行不同程度(T1:2℃/4h、T2:0℃/4h、T3:-2℃/4h)的低温处理,研究药隔期低温胁迫对小麦干物质积累、转运和分配及产量的影响.结果 表明:药隔期低温胁迫显著降低小麦干物质积累量,不同抗倒春寒性小麦品种间干物质积累量存在差异,抗倒春寒性弱的小麦品种降幅更大.其中烟农19的T1、T2、T3处理分别降低33.4％、46.2％和54.7％,而新麦26则分别降低了50.1％、59.3％和72.4％.不同处理小麦籽粒、穗轴+颖壳、茎鞘+叶的干物质积累量均低于CK,且随着低温胁迫程度的加重呈明显降低趋势.小麦花前干物质的转运量、转运效率以及花前贮藏干物质对籽粒的贡献率均随着低温胁迫程度加重呈降低趋势.同时低温胁迫显著降低小麦籽粒和穗轴+颖壳的干物质分配比例,增加茎鞘+叶的分配比例.T1、T2和T3处理显著降低了小麦的穗粒数和千粒重及籽粒产量,烟农19的T1、T2和T3处理分别减产56.06％、86.36％和98.10％;新麦26的T1、T2和T3处理分别减产96.15％、98.07％和98.46％.药隔期低温胁迫显著降低小麦干物质的积累量、花前干物质的转运量、转运效率以及花前贮藏干物质对籽粒的贡献率和籽粒干物质分配比例,严重减少光合同化物向穗部的转运和分配,影响穗部小花的正常发育,从而导致穗粒数的减少,这是造成小麦减产的主要原因.     

Current status and prospects of farming the giant river prawn Macrobrachium rosenbergii (De Man) in Bangladesh

Giant river prawn (Macrobrachium rosenbergii) farming plays an important role in the economy of Bangladesh. Presently, it is cultured in around 50 000 ha area with total annual production of 23 240 t. Traditional extensive prawn farming has been expanding over the last three decades through the introduction and adoption of improved culture systems, such as culture of prawn‐carps, prawn‐shrimp‐fish and prawn‐fish‐rice as concurrent and rotational systems. Efforts for the development of improved techniques on broodstock management, seed production and rearing and grow‐out of prawn have been made over the last decade. The outcomes are low‐cost feed for broodstock, production of post‐larvae in net cages (hapa), all‐male prawn culture, periphyton based prawn‐tilapia culture, C/N based prawn culture, organic prawn farming, prawn‐mola culture and prawn‐carp‐mola polyculture. Despite the development of culture technologies, a number of challenges for sustainable development of prawn farming need to be overcome to realize the potentials of this promising sector. Good aquaculture practises at all levels and application of measures for quality control and food safety would ensure sustainable development of prawn farming in Bangladesh.     

Pharmacokinetics of Enrofloxacin and Its Metabolite Ciprofloxacin after Intramuscular Administration of Enrofloxacin in Goats

The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats after a single intramuscular administration of enrofloxacin at 2.5 mg/kg body weight. The plasma concentrations of enrofloxacin and ciprofloxacin were determined simultaneously by a HPLC method. The peak concentrations (C _max) of enrofloxacin (1.13 g/ml) and ciprofloxacin (0.24 g/ml) were observed at 0.8 and 1.2 h, respectively. The elimination half-life (t _1/2), volume of distribution (V _d(area)), total body clearance (Cl_B) and mean residence time (MRT) of enrofloxacin were 0.74 h, 1.42 L/kg, 1329 ml/h per kg and 1.54 h, respectively. The t _1/2, area under the plasma concentration–time curve (AUC) and the MRT of ciprofloxacin were 1.38 h, 0.74 g h/ml and 2.73 h, respectively. The metabolic conversion of enrofloxacin to ciprofloxacin was appreciable (36%) and the sum of the plasma concentrations of enrofloxacin and ciprofloxacin was maintained at or above 0.1 g/ml for up to 4 h. Enrofloxacin appears to be useful for the treatment of goat diseases associated with pathogens sensitive to this drug.     

Ability of induced corpora lutea to maintain pregnancy in beef cows

Experiments were conducted in beef cows without a primary CL, in which pregnancy had been maintained with exogenous progestogen. In preliminary trials, replacement CL induced ipsilateral to the embryo and after, rather than before, d 36 of pregnancy, maintained more pregnancies after withdrawal of exogenous progestogen (13/13 vs 2/6; P < 0.05). In Exp. 1, in cows with replacement CL induced by treatment with hCG on d 28 of pregnancy, treatment with flunixin meglumine on d 31 through 37 did not increase maintenance of pregnancy. Experiment 2 was conducted to evaluate directly the effects of concentrations of PGF2alpha and estradiol-17beta during d 31 through 35 of pregnancy on maintenance of pregnancy by replacement CL induced between d 28 and 31. In cows that maintained pregnancy while progestogen was provided, maintenance of pregnancy after withdrawal of exogenous progestogen tended to be greater with high (5/5) than with low (2/6; P < 0.10) concentrations of PGF2alpha and greater with low (6/7) than with high (2/6; P = 0.10) concentrations of estradiol-17beta. Secretion of progesterone by replacement CL was greater (P < 0.05) in cows with high than in those with low concentrations of PGF2, during d 31 through 35. Prostaglandin F2alpha may facilitate attachment of the bovine embryo (d 30 to 40) in a manner similar to that reported for implantation in other species. Cows that did not form CL in response to hCG on d 28 to 31 responded well when retreated after d 36. Again, maintenance of pregnancy was greater when replacement CL were induced after (9/9) rather than before d 36 (8/16; P < 0.05).     

Involvement of CD28/CTLA4-B7 costimulatory pathway in the development of lymphadenopathy and splenomegaly in MRL/lpr mice

MRL/lpr mouse is an established animal model which develops autoimmune diseases including glomerulonephritis, sialoadenitis, hepatitis and inflammatory lung disease. Additionally, it has been reported that lpr strains uniquely accumulate CD3+ CD4- CD8- B220+ (double negative, DN) T cells in lymphoid organs leading to lymphadenopathy and splenomegaly. To investigate the role of CD28/CTLA4-B7 pathway in the development of lymphadenopathy and splenomegaly, MRL/lpr mice were treated with soluble form of CTLA4 molecules, CTLA4IgG, which efficiently blocks this pathway. It was demonstrated that (i) the development of DN T cells was independent of the CD28/CTLA4-B7 pathway, (ii) the CD28/CTLA4-B7 pathway was required for the development of lymphadenopathy and splenomegaly, (iii) the CD28/CTLA4-B7 pathway was important for the accumulation of various cell populations in the lymph node and spleen, (iv) composition of the accumulating cell populations was not altered by CTLA4IgG treatment, and (v) activation of conventional T cells and IL-4 production from conventional T cells were the CD28/CTLA4-B7 pathway dependent. Thus, we concluded that the CD28/CTLA4-B7 pathway was required for the development of full-blown lymphadenopathy and splenomegaly in MRL/lpr mice.     

肉鸡日粮电解质平衡与热应激的关系

在家禽业中,缓解热应激的方法涉及饲养管理和改变日粮配方等.管理制度方面如提高鸡舍隔热效果,有流畅的通风设施,屋顶安装喷水装置和蒸发制冷系统,使用鼓风机,降低饲养密度.……     

Effect of root applied 28-homobrassinolide on the performance of Lycopersicon esculentum

The roots of 20 days old seedlings of tomato (Lycopersicon esculentum Mill.) at the time of their transplantation, were dipped in 10⁻⁸, 10⁻⁷, 10⁻⁶ or 10⁻⁵ M of 28-homobrassinolide (HBR) for 15, 30 or 45 min and were allowed to grow in earthen pots, in a net house. The leaves of the plants, at days 30 and 60, possessed elevated quantities of nitrate reductase (NR), carbonic anhydrase (CA) and the contents of chlorophyll. The values for all the above characteristics were significantly higher than that of the water-fed control. The fruits borned at the treated plants were more in number and possessed a lower quantity of ascorbic acid than the control. Moreover, the fruits at ripening, had higher levels of lycopene and β-carotene. Among the treatments, 15 min feeding of 10⁻⁸ M HBR proved best.     

The Sepsis-Coagulant Axis: A Review

Activation of coagulation is a normal component of the acute inflammatory response. Inflammatory cytokines initiate coagulation events locally at sites of inflammation by converting endothelium from an antithrombotic surface to a prothrombotic surface; by stimulating tissue factor production, which activates both the extrinsic and intrinsic coagulation systems; and by stimulating production of platelet-activating factors. The fibrinolytic system is initially activated but is subsequently inhibited. This results in a marked imbalance in coagulation and fibrinolysis resulting in a net procoagulant state. When thrombin generation and platelet activation exceed the body's capacity to inactivate or remove these factors, disseminated intravascular coagulation (DIC) results. DIC directly contributes to multiple organ failure and death associated with sepsis. Presently available treatments (ie, heparin and aspirin) are relatively ineffective in treating DIC; however, newer, more potent drugs may soon be available for clinical use.     

Pyrrolizidine alkaloids from Senecio lorenthii.

The isolation and NMR spectra of otosenine (1) and seneciphylline (2) from Senecio lorenthii are reported.     

Wheat Seed Presoaking for Improved Germination

Seed presoaking improves wheat germination under marginal moisture conditions. The duration of seed presoaking was studied at The University of Arid Agriculture, Rawalpindi, using 10 wheat varieties. Seed presoaking beyond 12 h does not improve germination further, and beyond 21 h, germination rate is drastically reduced.