赤霉素对发育的大豆种子中同化物卸出和积累的影响

用微注射法将不同浓度的赤霉素 (GA3 )引入开花后 30 d的大豆种子幼胚的 2片子叶中间的质外体空间 ,同时给叶片饲喂 14 CO2 ,以种皮和子叶中放射性强度来比较分析 GA3 对同化物卸出的影响。分析了种皮和子叶中的酸性转化酶活性 ,发现 GA3 1× 10 -5mol.L-1使种皮中酸性转化酶活性提高而子叶中酶活性降低 ,从而促进种皮同化物的卸出和向子叶的分配。实验结果还表明 ,引入 GA3 影响了种子内源脱落酸 (ABA)水平 ,而且子叶中的 ABA含量变化和同化物积累相关 ,GA3 1× 10 -5mol.L-1使子叶中 ABA水平上升 ,伴随总糖、蔗糖和蛋白质的积累增加 ,GA3 1× 10 -4 mol.L-1却使 ABA水平下降 ,而且物质积累也减少     

大豆根特异性GmPR1-9启动子的鉴定及其在根腐病抗性中的应用

【目的】 鉴定大豆根特异性启动子及其最小调控片段,并利用启动子工程技术构建时空特异人工启动子并评价其在根腐病抗性中的应用价值,为大豆抗疫霉根腐病的遗传改良提供遗传元件。【方法】 通过分析大豆根、茎和叶片转录组数据,筛选在根中特异高水平表达的基因,克隆获得其启动子序列。根据顺式元件的分布位置构建截短载体,并驱动GUS报告基因在大豆发状根组织中超表达,筛选控制根特异性表达的核心片段。将获得的核心启动子片段与疫霉菌诱导启动子元件p4XD串联构建人工启动子驱动疫霉抗性相关基因GmNDR1在大豆发状根中超表达,分析转基因组织对疫霉菌抗性水平及目的基因在病原菌侵染过程中的表达水平。利用转基因本氏烟草从整株水平评价转基因材料对疫霉菌的抗性水平。【结果】 通过筛选发现6个大豆根特异性表达的PR1同源基因,其中,pGmPR1-9具有最高的启动子表达活性。PLACE在线预测发现其启动子区域含有大量的根特异表达相关顺式元件。对pGmPR1-9启动子进行截短试验,发现5′端截短片段L1、L2、L3、L4和L5均具有启动GUS表达活性,长度为166 bp的L5（-166—-1）片段具有全长启动子80%的活性,并可驱动GUS在转基因烟草根中特异表达;3个3′端截短片段R1、R2、R3和1个双端截短片段M1几乎检测不到GUS酶活性。p4XD-L5融合片段驱动GmNDR1在大豆发状根中超表达后可显著提高大豆发状根对疫霉菌的抗性,超表达发状根接种病原菌后发病程度和病斑长度显著低于对照,疫霉菌丝积累量在接种48 h时减少66.5%。GmNDR1在超表达组织中始终维持在高表达水平,在接种前,表达量是对照组织的39.2倍,接种后,表达量受疫霉菌侵染诱导进一步上调,并在36 h达到最高。GmNDR1在p4XD-L5::NDR1转基因本氏烟草根中的表达量显著高于茎和叶片,表现出明显的根部表达偏好性。超表达株系接种辣椒疫霉菌15 d后的株高、根长和鲜重显著高于对照,同时叶片萎蔫率和病斑长度显著低于对照植株。【结论】 鉴定获得一个大豆根特异性表达启动子及其核心序列,融合诱导性和组织特异性启动子核心元件的人工启动子p4XD-L5驱动抗性基因GmNDR1超表达,可显著增强转基因大豆发状根和本氏烟草对疫霉菌的抗病性。     

Effect of glycine betaine, a feed attractant affecting growth and feed conversion of juvenile freshwater prawn Macrobrachium rosenbergii

A feeding experiment was conducted to determine the effect of the feeding attractant, glycine betaine (betaine hydrochloride) on the growth and feed conversion of juveniles of Macrobrachium rosenbergii (deMan) (mean initial weight 1.12 g). Three types of diets were prepared with the incorporation of glycine betaine at 5, 10 and 15 g kg^?1 levels along with an unsupplemented control. After 60 days, weight gain, feed intake and food conversion ratio (FCR) were higher in prawn fed the three glycine betaine‐added diets compared with the control feed. Among the glycine betaine‐added diets, prawn fed glycine betaine at 5 g kg^?1 level showed highest weight gain (2.73 g) by registering 61.5% increase in growth over control and also higher feed intake (5.79 g) and good FCR (2.12). There were highly significant differences (P < 0.01) in weight gain, feed intake, per day growth and FCR among treatments. There was no significant difference (P > 0.05) in survival among treatments.     

Oxygen uptake in the Antarctic teleost Pagothenia borchgrevinki. Limitations imposed by X-cell gill disease

Fish in a population of Pagothenia borchgrevinki in McMurdo Sound, Antarctica, are affected by a gill disease (X-cell disease) which causes tissue hyperplasia that results in a decreased gill surface area and an increased water/blood diffusion distance. P. borchgrevinki acquires 95% of its oxygen via the gills, but damage to the gills by X-cell disease did not affect this function. There was no compensatory shift to cutaneous respiration. X-cell disease reduced the ability for oxygen uptake at low ambient P_{O 2} and the decreased uptake was related to the extent of the disease. _{O 2} max was greatly reduced in X-cell affected fish and substantially reduced their aerobic potential. This effect may impair the ability of diseased fish to catch prey and avoid predators.     

Predation by scavenging amphipods to injured hatchery-raised juvenile Japanese flounder Paralichthys olivaceus under laboratory conditions

ABSTRACT:   The attacking potential of the scavenging amphipod Scopelocheirus onagawae on artificially injured hatchery-raised Japanese flounder Paralichthys olivaceus juveniles was investigated in relation to the degree of injury on the fish. All injured flounder juveniles were attacked by amphipods regardless of the degree of injury, while non-injured juveniles were not attacked. The attack by amphipods on the juveniles generally depended on the amount of glycine, a main feeding stimulant for the amphipod, released from the injury opening. The swimming ability of flounder juveniles was important to avoid the attack of amphipods. Furthermore, an area of injury allowing the amphipods to cling to the fish affects to the vulnerability of juveniles against the predation of amphipods. This study suggests that scavenging amphipods are potentially involved in the rapid reduction of the number of hatchery-raised juveniles.     

Overcoming the Stressful Effect of Low pH on Soybean Root Hair Curling using Lipochitooligosacharides

Abstract

Signal molecules are among the major factors required for the legume–bacteria symbiosis. The excretion of signal molecules by plants stimulates the bacterial Nod genes resulting in the production of lipochitooligosacharides (LCOs). LCOs cause root hair deformation (RHD) and induction of nodule cells division, leading to the formation of nodules. The chemical structure of LCOs determines their biochemical activities; for example, removal of the sulfate group can significantly reduce the morphogenic activities of LCOs. Stressful conditions interrupt the excretion of signal molecules by the legumes' roots and consequently the inhibition of LCO production by the bacteria. This research has studied the effect of different concentrations of LCOs on RHD of two soybean [Glycine max (L.) Merr] cultivars, AC Bravour and Maple Glen, under acidity stress. In the first experiment, two different concentrations of LCO (10^?7 and 10^?6M) and in the second experiment, three different concentrations of LCO (10^?7, 10^?6, and 10^?5M) were added to the soybean roots subjected to the pH levels of 4, 5, 6, and 7 for 24 h. By microscopy observation, the ratios of RHD were determined. Addition of LCOs resulted in RHD in both cultivars. Maple Glen roots responded similarly to different concentrations of LCO, whereas roots of AC Bravour responded differently. The concentration of 10^?5M LCO could inhibit the stressful effect of pH 4 on RHD compared with pH 7 in both cultivars. The significant interaction between LCO and pH suggests that the effect of LCO on RHD may be more significant under higher levels of acidity.     

Acknowledgment to the Reviewers

Abstract

Gram-positive bacterium BRF-1 isolated from the rhizosphere of root-rotten diseased soybean plants shows strong antifungal activity on plates. In the present study, the ability of BRF-1 to control brown stem rot disease and to promote plant growth was examined using soybean plants grown in pots. Brown stem rot is a severe soil-borne disease of soybean that is caused by the pathogenic fungus Phialophora gregata. Eighteen-day-old soybean seedlings were grown in a mixture of soil (40 mL) and BRF-1 suspension (10 mL) and were dipped in a suspension of P. gregata (10⁶ c.f.u. mL^?1), and the severity of the disease was judged 62 days after the fungal inoculation. Inoculation with BRF-1 at 10⁷ and 10⁸ c.f.u. mL^?1 significantly lowered the severity of the disease. Soybean seeds incubated in 100 mL of the BRF-1 suspension (2 × 10⁶ c.f.u. mL^?1) were sown in pots filled with sand, and plants were collected 7 days after emergence. The dry weight increase in shoots and roots and mineral absorption were significantly stimulated by the inoculation. These results suggest that BRF-1 might be an effective biocontrol agent to manage brown stem rot disease in soybean. The 16S rDNA sequence of BRF-1 showed high homology with sequences of Paenibacillus polymyxa strains (e.g. 99.7% identity with P. polymyxa strain WY110).     

不同光周期处理对大豆开花结荚进程的影响

通过长日照（１６ｈ光／８ｈ暗）和短日照（９ｈ光／１５ｈ暗）相互转换处理，证明大豆品种“早１２”为相对短日植物，９个短日就可完成其成花的光周期诱导过程。大豆感受光周期效应的株龄在真叶期。短日诱导处理不仅促进花序产生的速度及数量，还有利于荚的发育；长日处理的结果恰相反。     

不同品种大豆耐盐性的比较研究

通过对中黄13号和科丰6号2个大豆品种进行不同浓度的盐处理(01、002、00 mmol/L NaCl)后,测定其干重、脯氨酸、丙二醛、叶绿素含量以及根系活力和过氧化物酶活性等相关生理指标,通过其生长及生理指标变化,比较2个大豆品种的耐盐性并探讨其耐盐机理。结果表明:随着盐浓度的增加,2个大豆品种幼苗叶绿素含量、根系活力以及过氧化物酶活性均降低,脯氨酸、丙二醛含量均增加,最终导致幼苗干重的下降,但品种间生理指标变化趋势不同,科丰6号较中黄13号变化缓慢,说明前者耐盐性较强。     

The Effect of Ivermectin on Convulsions in Rats Produced by Lidocaine and Strychnine

Ivermectin is one of the most commonly used drugs in pharmacotherapy of parasitic diseases in domestic and wild animals caused by parasitic nematodes and arthropods. However, ivermectin and other avermectins very often produce side-effects in hosts. The most dominant clinical symptom of ivermectin toxicity in domestic and wild animals is CNS depression. In nematodes, the target site of ivermectin’s action is glutamate-gated chloride-channel receptor and GABA receptor. The depressive effect of ivermectin in mammals might include more than one mechanism; therefore, the anticonvulsive effect of ivermectin against convulsions caused by lidocaine and strychnine was evaluated. Ivermectin antagonized lidocaine- and strychnine-induced convulsions in rats, although these have different mechanisms. In the present study, the anticonvulsive ED₅₀ of ivermectin for lidocaine-induced convulsions was 2.44 mg/kg (95% CL 1.67 to 3.57 mg/kg), whereas for convulsions induced by strychnine it was higher at 4.25 mg/kg (95% CL 2.32 to 3.78 mg/kg). At the same time, both anticonvulsive doses are significantly lower then the observed LD₅₀ of ivermectin (18.20 mg/kg). Furthermore, flumazenil (0.1 and 0.2 mg/kg), an antagonist of benzodiazepine receptors, antagonizes just one part of these anticonvulsive effects of ivermectin. Our results show the significant anticonvulsive properties of ivermectin and support the findings that ivermectin in the CNS of mammals produces multiple inhibitory effects, probably through participation in the function of GABA-sensitive and GABA-insensitive chloride channels.