Survival of antibiotic resistant Pseudomonas strains in different types of water

A study was conducted to investigate the survival of five Pseudomonas strains resistant to antibiotics in different types of water. The selected Pseudomonas strains were designated as strain P1 (CT-29), strain P2 (CT-25), strain P3 (CT-36), strain P4 (CT-20) and strain P5 (CT-27) which were only recovered from farmed fishes. Six types of water viz., distilled water, saline water, tap water, deionized water, pond water and river water were used. Among these experimental waters, river water was found to be the most suitable for long-term survival of these strains. Deionized water did not support survival of all these Pseudomonas strains. Pond water, tap water and distilled water were moderately suitable for strain P1 and strain P4. Saline water was also found to be highly suitable for long-term survival in case of the strain P3 and moderately suitable for normal survival of strain P2 and strain P5.

光敏核不育水稻41 kDa和61 kDa蛋白质的发现、N-端序列分析及其雄性不育性状关系的探讨

光敏核不育水稻农垦58S是石明松于1973年在晚粳农垦58的大田中发现的雄性不育突变体，它在长日照下雄性不育可被用于与恢复系杂交生产杂种，而在短日照下雄性可育能用于自交繁殖，它的恢复系来源广泛。基于这些特性，育种学家用光敏核不育水稻建立的二系杂交水稻制种技术有很大的应用潜力。近十几年来，育种学家用农垦58S作基因供体转育了许多新的不育系，研究结果表明育成的粳型不育系均为光敏不育系，但在育成的籼型不育系中，绝大多数丧失光敏核不育特性，变成温敏不育系。目前因不知光敏核不育的分子遗传机制，尚不能解释这些问题。 本文用双向电泳技术分析了农垦58S和农垦58苗期和育性转换光敏感期叶绿体蛋白质的差异，在农垦58S中发现三个蛋白质(Pl，P2和P3)，其中Pl和P2在苗期和光敏感期叶片内均存在，P3仅在光敏感期的叶片中存在，它们不受长日照或短日照处理的影响。农垦58没有这三个蛋白质。 用制备型双向电泳纯化后，得到SDS - PAGE和IEF纯的Pl和P2。经SDS-PAGE和IEF测定，Pl的等电点是6.2，分子量是41 kDa;P2的等电点是5.8，分子量是61 kDa。现称Pl为P41，P2为P61。氨基酸序列分析和同源性检索发现P41与水稻叶绿体ATP合成酶p亚基和酵母转录因子CAD1有同源性，此外，P41的N-端序列中有一个与蛋白激酶催化核心中的多功能motif Y-G-X-G-X- (P/T)-G-V相似的序列;P61的14个氨基酸长的N-端序列与水稻叶绿体ATP合成酶β亚基的一致。P41和P61 N-端前12个氨基酸的序列也完全一致。 PCR扩增和Southern杂交分析没有发现农垦58S和农垦58之间ATP合成酶β亚基基因(atpB)的多态性。Nothern杂交分析表明农垦58S中仅有一种、与农垦58 atpB mRNA分子量相同的atpB转录产物，但它的atpB mRNA丰度明显低于农垦58的。没有检测到突变的atpB和其它形式的atpB转录产物。 分析P41和P61在其它水稻材料中的分布特点发现它们在粳型光敏不育系7001S、5088S、31301S、C407S和1647S，籼型光敏不育系W7415S和W9451S以及温（光）敏不育系培矮64S中存在，而在对照材料三系水稻马协A、珍汕97A、马协B、珍汕97B和明恢63以及常规粳稻C94153中不存在。根据这些不育系的系谱和它们与农垦58S之间基因的等位性研究结果，讨论了P41和P61与光敏核不育性的可能联系。

蒲葵籽提取物体外抗HIV-1活性及机制的初步研究

下载PDF阅读器目的 研究蒲葵籽提取物的体外抗HIV-1活性,对有活性粗提物进行初步机制研究.方法 采用细胞毒性、合胞体抑制、HIV-1感染细胞保护实验和HIV-1 p24抗原测定等实验对蒲葵籽提取物体外抗HIV-1活性进行筛选和确认;采用重组HIV-1逆转录酶和蛋白酶活性抑制实验,融合阻断实验初步探讨活性粗提物的作用机制.结果 蒲葵籽的醋酸乙酯(P3)提取物具有较强的体外抗HIV-1活性,P3抑制HIV-1诱导C8166细胞形成合胞体的EC50为5.64 pg/mL,对C8166细胞的毒性较小,CC50大于200 μg/mL,治疗指数(T1)大于35.46;P3抑制HIV-1急性感染中p24抗原表达的EC50为23.04 μg/mL,抑制正常C8166细胞与慢性感染细胞Hg/HIV-1-B融合的EC50为8.00 μg/mL;P3在质量浓度为200μg/mL时,对HIV-1逆转录酶的抑制率为28.86%;P3抑制重组HIV-1蛋白酶活性的EC50为1.77μg/mL.结论 蒲葵籽的醋酸乙酯提取物(P3)具有较强的体外抗HIV-1活性,其作用机制可能主要为阻断病毒进入和抑制HIV-1蛋白酶活性.

Effects of different levels of energy and protein sources on the growth performance, feeding, survival rate and the chemical body composition of juvenile Pacific white shrimp (Litopenaeus vannamei)

The present study was carried out in order to establish an economical effective diet for the pacific white shrimp in the southern part conditions of Iran. With the consideration of three dietary energy levels (E1=262, E2=312, E3=362 kcal 100 g-1 diet) and six ratios of fish meal (FM) to soybean meal (SBM) [(P1=100%FM+0%SBM, P2=80%FM+20%SBM, P3=60%FM+40%SBM, P4=40%FM+60%SBM, P5=20%FM+80%SBM, P6=0%FM+100%SBM)], 18 experimental diets (with 36% crude protein) were prepared. Completely randomized design was used to assign 54 polyethylene 300 litre round tanks provided by aeration and flow through water system and was stocked by 19 juvenile as 3 replicates to each treatment. Shrimps average weight was about 0.77 grams at the start. After 56 days culture period, maximum growth and nutritional performances were observed in the P6E1 treatment (containing 100% soybean meal and 262 kcal 100 g-1 diet) and P5E1 treatment (containing 80% soybean meal and 262 kcal 100 g-1 diet). Also the highest survival rate of the shrimps was observed in the P1E1, P1E2, P3E3 and P5E3 treatments. Additionally interactive effect of different protein ratios and energy levels had significant difference on body protein, fat, fiber and ash contents (P<0.05). Results of the present study suggest the possibility replacement of at least 80% of dietary fish meal by soybean meal in the diet of pacific white shrimp in the conditions of southern part of Iran.

池塘养殖环境下滇池金线鲃仔稚鱼的食性转化与生长

下载PDF阅读器2008年3月-2009年3月,把35 000尾滇池金线鲃(Sinocyclocheilus grahami)仔稚鱼分别饲养于3个池塘进行对比饲养研究.密度分别是:P1为208尾/m3;P2为167尾/m3;P3为41尾/m3.饲养期间采用相同的管理措施.每天数据收集采用:在仔鱼孵化后的5～16d的每天8:00和18:00从每个育苗池中捞取5～8尾仔鱼进行测量分析.仔鱼开口30d后,每月从培育池各捞取15尾,测量全长和体重.研究发现,滇池金线鲃仔鱼的开口时间为孵化后的5 d,混合营养期3～5d,这与初孵的演池金线鲃仔鱼的全长和卵黄囊较大有关.在容易造成仔鱼大量死亡的混合营养期,通过采用浆状物-轮虫-人工混合饲料的方式,大幅度提高了滇池金线鲃仔稚鱼的存活率,孵化一年后的滇池会线鲃稚鱼存活率可达82.7%.经过一周年的饲养,滇池金线鲃稚鱼的体重由(0.027±0.01)g(0.003～1.22)增长到(8.83±0.54)g (3.7～16.7),月均增重为0.73 g;全长由(15.8±0.30)mm (11.5～20.0)增长到(91.6±1.67)mm (75.0～16.0),全长月均增长6.32 mm.滇池金线鲃稚鱼全年全长的增长呈线性相关,y=9.82+7.05month(R2=0.9891);全年体重的增长呈指数关系,y=0.0158month2.54(R2=0.9939).

Intergroup interactions in Tibetan macaques at Mt. Emei, China

Data on intergroup-interactions (I-I) were collected in 5 seasonally provisioned groups (A, B, D, D-1, and E) of Tibetan macaques (Macaca Thibetana) at Mt. Emei in three 70-day periods between 1991 April-June (P1), September-November (P2), December-1992 February (P3). The I-I were categorized as forewarning made by high-ranking males (including Branch Shaking and/or Loud Calls), long-distance interactions in space (specified by changes in their foraging movements), and close encounters (with Affinitive Behavior, Male's Herding Female, Sexual Interaction, Severe Conflict, Adult Male-male Conflict, Opportunistic Advance and Retreat, etc. performed by different age-sex classes). From periods Fl to P3, the I-I rate decreased with reduction in population density as a positive correlate of food clumpedness or the number of potential feeders along a pedestrian trail. On the other hand, from the birth season (BS, represented by P1 and P3) to the mating season (MS, represented by P2) the dominance relation between groups, which produced a winner and a loser in the encounters, became obscure; the proportion of close encounters in the I-I increased; the asymmetry (local groups over intruders) of forewarning signals disappeared; the rate of branch shaking decreased; and sometimes intergroup cohesion appeared. Considering that sexual interactions also occurred between the encountering groups, above changes in intergroup behaviors may be explained with a model of the way in which the competition for food (exclusion) and the sexual attractiveness between opposite sexes were in a dynamic equilibrium among the groups, with the former outweighing the latter in the BS, and conversely in the MS. Females made 93% of severe conflicts, which occurred in 18% of close encounters. Groups fissioned in the recent past shared the same home range, and showed the highest hostility to each other by females. In conspicuous contrast with females' great interest in intergroup food/range competition, adult male-male conflicts that were normally without body contact occurred in 66% bf close encounters; high-ranking male herding of females, which is typical in baboons, appeared in 83% of close encounters, and showed no changes with season and sexual weight-dimorphism; peripheral juvenile and subadult males were the main performers of the affinitive behaviors, opportunistic advance and retreat, and guarding at the border. In brief, all males appeared to "sit on the fence" at the border, likely holding out hope of gaining the favor of females both within and outside the group. Thus, females and males attempted to maximize reproductive values in different ways, just as expected by Darwin-Trivers' theory of sexual selection. In addition, group fission was observed in the largest and highest-ranking group for two times (both in the MS) when its size increased to a certain level, and the mother group kept their dominant position in size and rank among the groups that might encounter, suggesting that fission takes a way of discarding the "superfluous part" in order to balance the cost of competition for food and mates within a group, and the benefit of cooperation to access the resources for animals in the mother group. (C) 1997 Wiley-Liss, Inc.

复合养殖系统中浮游动物种类丰度及其影响因素

利用人工湿地和养殖塘构建了复合养殖系统,通过设置不同塘间水质差异,调查了斑点叉尾鮰鱼鱼种培育段和成鱼养殖段不同梯度下的浮游动物种类丰度,并探讨了种类丰度与环境因子的关系.结果表明,2养殖阶段的循环塘中,轮虫的种类丰度随养殖密度的增加而升高,浮游甲壳动物随养殖密度的增加而降低.成鱼养殖阶段对照塘中轮虫的种类丰度高于循环塘P1、P2;枝角类和桡足类的丰度则低于P1、P2;高养殖密度塘P3中,3种形态浮游动物种类丰度均低于对照塘.15种环境因子的主成分分析以及种类丰度与环境因子的冗余度分析结果表明,影响浮游动物

灰盔累枝虫形态学及表膜下纤维系的研究

利用活体观察及蛋白银染色技术对灰盔累枝虫(Epistylisgalea)的形态学及表膜下纤维系进行了研究。该种主要鉴别特征为:活体个员的表膜柔软,虫体充分伸展时呈倒长锥形,体长200—300μm,体宽70—90μm;大核“J”字形,呈纵位。单一伸缩泡,直径21—25μm,背位。纵向纤维细密。口围盘纤维呈网状,与纵向纤维直接相连,并在整体上呈兜网状。与本属其他相近种相比,本种第3咽膜(P3)明显要长,其后1/3超出第1咽膜后继续向下呈弧形弯曲。本文对该种上述特征在分类学上的意义及其与相近种类之间的关系进行了

钟形钟虫形态学及表膜下纤维系统的研究

利用活体观察及蛋白银染色技术对钟形钟虫的形态学及表膜下纤维系统进行了研究 ,分别给出活体及蛋白银制片后标本的鉴别特征及表膜下纤维系统。本种活体鉴定主要特征为虫体呈宽钟状 ,细胞质不透明 ,镜下明显可见有散布的脂滴存在。蛋白银制片特征为口器明显呈横位 ,第 1(P1)和第 2咽膜 (P2 )汇合后形成的短咽膜弯曲程度较甚。纵向纤维粗壮而稀疏 ,40— 5 0条 ;口围盘纤维网粗壮 ,呈轮辐状排布 ,相邻两轮辐外部末端多呈闭合态 ;第 3咽膜 (P3)由 3排毛基索组成 ,其靠近P2 侧的一列毛基索在P1与P

保水剂对宁南山区马铃薯产量及土壤水分利用的影响

在宁南半干旱黄土丘陵区探讨大田施用PAM、沃特保水剂对马铃薯产量和土壤水分利用的影响。结果表明:PAM、沃特均可促进马铃薯生长、提高块茎产量,其中PAM 9.0 kg/hm2(P3)和沃特15 kg/hm2(W1)、沃特30kg/hm2(W2)、沃特60 kg/hm2(W3)处理马铃薯生物量和块茎产量显著高于CK(P<0.05),增产效果最明显。幼苗期、块茎形成期和块茎生长期各处理耗水量无显著差异,淀粉积累期CK耗水量极显著高于施用保水剂处理(P>0.01)。保水剂处理耗水量随着马铃薯生物量的增加而增大,降雨对土壤水分的补充随生物量的增大而减少。利用有序聚类分析得出,淀粉积累期降雨对土壤0~60 cm的水分储量有明显的补充,施用PAM和沃特两种保水剂,0~140 cm各层土壤储水量恢复相近,而140 cm以下土层沃特的恢复能力优于PAM,平均每20 cm土层储水量较PAM高6.2 mm。随着PAM施用量的增加水分利用效率提高,沃特保水剂则相反。沃特15 kg/hm2和PAM 9 kg/hm2处理水分利用效率、水分产出效率最高。通过对马铃薯产量和水分利用特征得出,PAM的用量为9 kg/hm2、沃特15kg/h...

半结晶性嵌段共聚物自组装与薄膜微相分离

本论文以半结晶性的PLLA-b-PS为研究对象，主要研究两个方面的问题。首先研究聚合物结晶对嵌段共聚物在稀溶液中的自组装行为的影响。在此基础上，研究薄膜状态下，聚合物结晶与微相分离之间的相互作用。首先，我们系统地研究了PLLA-b- PS在不同溶剂中的自组装结构。通过调节溶剂选择性由中性向弱选择性和选择性改变，PLLA-b-PS分别形成类旋节图案，松散的胶束结构和典型的胶束核壳结构。使用混合溶剂，实现了从结晶性的球形胶束向结晶性的片状胶束的转变。标度理论分析和实验结果表明，溶剂与胶束结晶核心之间的界面能的增加是发生这一转变的主要原因。为了研究薄膜中的微相分离与结晶之间的相互作用，我们比较了三种薄膜条件下的相分离与结晶过程。均匀平坦的PLLA-b-PS薄膜是旋节不稳定的，在几以上时，分子链发生微相分离，形成旋节图案，表面诱导分子链的伸展有序化过程促使PLLA分子链发生折叠结晶，形成非经典的亚稳态凸出结构，相分离层间距增大50％。结晶过程为一级动力学。在薄膜中引入成核剂时，PLLA在几以上即开始结晶，同时实现了PLLA与P3之间的相分离，薄膜的旋节不稳定性得到了松弛。结晶使薄膜收缩，形成大量的裂纹。在PLLA熔点以上时，以裂纹为核，在薄膜中形成大量的孔洞。孔洞的生长为经典的动力学过程。我们利用自组装方法在薄膜中引入半结晶性的开放的纳米棒。在几以上时，PLLA在纳米棒中发生结晶，诱导薄膜中的分子链向纳米棒迁移，从而在薄膜中形成孔洞结构。同时，薄膜中的未结晶分子链被表面和界面诱导取向，这种取向结构利于PLLA结晶，结晶被加速，从而孔洞的生长也被加速。也就是说，结晶与孔洞的生长相互促进。在相分离薄膜中，PLLA的结晶形态与结晶温度有关。To＜TgPS时，结晶被束缚在相结构中，相分离结构不变；TgPs＜Tc＜Tm以及Tc→Tm时，结晶对相结构有一定的破坏，相分离片层结构的层间距增大，薄膜收缩，形成大量的裂纹和缺陷。在180℃时，PLLA形成不稳定的晶体结构；PLLA与PS之间的相分离强度被减弱，在线张力作用下，岛状结构的相对高度大幅度增加；在岛状结构的边缘，线张力驱使部分分子链穿越已有的相结构，形成多层岛状结构。