Biological control of Botrytis cinerea and plant growth promotion potential by Penicillium citrinum in chickpea (Cicer arietinum L.)

A total of 48 fungi were characterised for their antagonistic potential against Botrytis cinerea causing Botrytis Gray Mold (BGM) disease in chickpea by dual culture and metabolite production assays. The culture filtrate of the most promising isolate, VFI-51, was purified by various chromatographic techniques and identified as ‘citrinin’ by nuclear magnetic resonance and mass spectrometry studies. The efficacy of citrinin was demonstrated to control BGM in chickpea under greenhouse conditions. The sequences of 18S rDNA gene of the VFI-51 matched with Penicillium citrinum in BLAST analysis. The VFI-51 produced siderophore, hydrocyanic acid, indole-3-acetic acid, lipase, protease and β-1,3-glucanase; grew well in NaCl (up to 15%), at pH between 7 and 11 and temperatures between 20°C and 40°C; and was compatible with fungicides bavistin and thiram. Under greenhouse and field conditions, VFI-51 significantly enhanced the nodule number, nodule weight, root and shoot weight and stover and grain yield over the un-inoculated control. In the rhizosphere, VFI-51 also significantly enhanced total N, available P and OC over the un-inoculated control. Scanning electron microscopy analysis revealed that VFI-51 colonised on the roots of chickpea. This study concluded that VFI-51 has the potential for biocontrol of BGM and plant growth promotion in chickpea.     

长江葛洲坝枢纽坝下江段中华鲟成鱼性腺的观察

1981年1月,葛洲坝水利枢纽截流,中华鲟被大坝所阻而滞留在宜昌以下的江段。 1981年秋季在葛洲坝枢纽的坝下江段采集到中华鲟的Ⅲ、Ⅳ、Ⅵ期卵巢和Ⅲ、Ⅳ、Ⅴ期精巢,1982年秋季又采集到中华鲟产出的卵和早期鱼苗。研究结果表明,中华鲟在坝下江段不仅能发育成熟,而且能自然产卵。为了保护和增殖中华鲟,人工繁殖放流的方法是切实可行的。同时,必须严禁滥捕,以保护中华鲟资源。       

Comparison of the frequency of diphtheria toxin and thioguanine resistance induced by a series of carcinogens to analyze their mutational specificities in diploid human fibroblasts

The mutagenic specificities of ethylnitrosourea (ENU), X-rays (+/-)7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7, 8,9,10-tetrahydrobenzo[a]pyrene (BPDE), ICR-191, and N-acetoxy-2-acetylaminofluorene (N-AcO-AAF) were analyzed and compared in diploid human fibroblasts and Salmonella typhimurium. In the human fibroblasts, we compared the frequency of diphtheria toxin (DT)-resistant mutants, presumably induced in the gene coding for elongation factor-2, with the frequency of 6-thioguanine (TG) resistance induced by mutations in the gene coding for hypoxanthine(guanine)phosphoribosyltransferase (HPRT). Recovery of DT-resistant (DTr) cells requires that the mutant EF-2 retain the ability to carry on protein synthesis since the normal EF-2 will be inactivated by DT selection. Therefore, the DTr mutation cannot involve major changes in the gene. In contrast, cells can acquire TG resistance by any mechanism which eliminates HPRT activity, e.g., base substitution, frameshift, deletion, loss of chromosomes. Each agent was assessed by calculating the ratio of the slopes of the dose-response plots (induced variant frequency as a function of dose of the agent used) for the two markers (DTr/TGr variants.). In S. typhimurium we examined the reversion frequency in four histidine-requiring strains bearing forward mutations of the frameshift (TA1538, TA98) or missense (TA1535, TA100) type. ENU, which was predominantly a base substitution mutagen in the bacteria, gave a ratio of DTr to TGr variants of 1.5. As expected of an agent inducing gross chromosomal changes, X-rays induced no revertants in bacteria and in human cells gave a ratio of 0.1. ICR-191 which was predominantly a frameshift mutagen in bacteria gave a ratio of 0.15. In the set of bacterial strains containing the plasmid pKM101, BPDE reverted both frameshift and base substitution mutations. It did not cause reversions in the other set of strains. In human cells BPDE gave a response similar to ENU, i.e., a ratio of DTr/TGr variants of 1.5. As reported by others, N-AcO-AAF was predominantly a frameshift mutagen in bacteria. However, in the human cells it gave a ratio of DTr/TGr variants of 1.5, similar to ENU and BPDE. These results suggest that in human cells, BPDE and N-AcO-AAF, like ENU, yield predominantly base substitutions, while ICR-191 and X-rays largely produce mutations by mechanisms which result in more extensive alterations in the gene.     

Flow-cytometric characterization and sorting of plant chromosomes

Summary Flow cytometric measurements of DNA frequency distribution were used to follow the synchronization process in suspension cells from Haplopappus gracilis (2n=4). Metaphase chromosomes were isolated from these synchronized cells and both the acro- and metacentric chromosomes were sorted by flow cytometry based on the different DNA contents. Possible applications of this procedure in fundamental genetics as well as practical plant breeding are discussed.     

A field study of the headbob displays of male green iguanas (Iguana iguana): Variation in form and context

Headbob displays play an important role in the social behaviour of male green iguanas (Iguana iguana). Four types of headbobs were identified, and the variability in form and context were determined from quantitative analyses of displays filmed in the field. The Roll is a conspicuous advertisement display. The Shudder, the most variable in form, occurred during close contact between males and females. The Roll-shudder is intermediate between the Roll and Shudder in its form and use. The Signature Bob, the most stereotyped display in form, punctuates much activity and is the most variable in contextual use. This display encodes species identity, and possibly individual identity. The conspicuous nature of the headbob displays was enhanced by the intensified colour of territorial males, and by the selection of highly visible display posts. This system of visual displays is viewed as the product of related sets of constraints, including the iguanas' physical capacities, the forest environment, and the social environment.     

Antigenic differences between tumor-associated fetal antigens and rat histocompatibility antigens

Certain molecular properties of purified tumor-associated fetal antigens (TAFA) were analyzed by sequential immune precipitation (SIP), isoelectric focusing, and high-pressure liquid chromatography (HPLC). The antigenic relatedness of rat histocompatibility antigens and the various TAFA were determined by SIP. SIP of chloramine-T-labeled purified TAFA or lactoperoxidase-iodinated tumor cell membranes, in the presence of rat alloantisera and monospecific rabbit anti-TAFA sera demonstrated no antigenic cross-reactivities or similarities between H-antigens and TAFA. TAFA were also compared with histocompatibility antigens for isoelectric point optima and molecular weight. Rat H-antigens had isoelectric points in the 7.0–8.5 pH range, whereas all TAFA focused at pH 5.0–6.5 or above pH 8.0. Molecular weights were determined by HPLC. TAFA-I and TAFA-III had molecular weights of 16,000–17,500 daltons, whereas TAFA-II had a molecular weight of 12,000. The antigens were not coprecipitated by the rat alloantisera. Each TAFA was also isolated (via immune precipitation) from NP-40-solubilized tumor cell membranes. These TAFA were identical to the chloramine-T-labeled TAFA which had been previously extracted and purified from rat fibrosarcomas and osteosarcomas. These studies demonstrated that although TAFA and H-antigens cocap on embryonic and transformed cell membranes, these determinants are different molecules; they are not covalently linked on cell membranes; and TAFA are not cleavage products of normal NBR H-antigens.     

Role of Competition for Sugars by Yeasts in the Biocontrol of Gray Mold of Apple

The yeasts, Cryptococcus laurentii BSR-Y22 or Sporobolomyces roseus FS-43-238, but not Saccharomyces cerevisiae BY-1, reduced gray mold ( Botrytis cinerea ) when applied to wounds of apples (cv. Golden Delicious) which were stored at 22IC for 7 days or 3IC for up to 2 months. The role of competition for sugars by these yeasts as a mechanism of antagonism was investigated at 22IC. Populations of C. laurentii and S. roseus in wounds were 6-9 times greater than those of S. cerevisiae from 1 to 7 days following inoculation. Yeasts in wounds utilized more 14C-labelled fructose, glucose or sucrose than conidia of B. cinerea during 48 h, but yeasts did not differ in their utilization of sugars. Utilization of 14C-sugars by yeasts in vitro was greater at most sampling times for conidia; the uptake after 48 h was always greater for yeasts and the addition of nitrogen did not alter this result. The utilization of 14C-sugars by S. roseus in vitro was greater than that in the other yeasts. The uptake and utilization of 14C-fructose by C. laurentii or S. roseus was greater than that of S. cerevisiae , but the utilization of glucose or sucrose by C. laurentii and S. cerevisiae was similar and the uptake of these sugars by these yeasts did not differ. Yeasts mixed with conidia in sterile, dilute solutions of fructose, glucose or sucrose, or in dilute apple juice inhibited conidial germination compared with no-yeast controls; S. cerevisiae was less effective than C. laurentii or S. roseus . Only yeasts rapidly depleted sugars from juice or sugar solutions. Yeasts did not alter the pH or oxygen content of dilute juice to the detriment of conidial germination. These results strongly suggest that competition for sugars by yeasts played a role in the biocontrol of gray mold, but that some other factor(s) most likely contributed to differences in efficacy between the yeasts.     

平颏海蛇3种短链神经毒素的基因克隆与功能比较

通过构建平颏海蛇毒腺cDNA文库得到 3个编码短链神经毒素的cDNA ,sn12、sn36和sn16 0 ,它们编码6 0个氨基酸的成熟肽 ,氨基酸序列比较表明三者之间只存在第 46位氨基酸残基的差异 ,分别为Pro4 6、His4 6和Arg4 6。在大肠杆菌中重组表达以上 3种同源序列 ,重组神经毒素SN12、SN36和SN16 0对昆明小鼠 (i.p .)的半致死剂量 (LD50 )分别是 0 .0 95 6mg/kg、0 .346 7mg/kg和 0 .2 192mg/kg ;在对昆明小鼠 (i.p .)的醋酸扭体反应镇痛实验中 ,SN12和SN16 0表现出相似的效果 ,而SN36则存在明显的差异。平颏海蛇短链神经毒素SN12、SN36和SN16 0之间只存在第 46位氨基酸残基的差异 ,在生物活性上却显示出明显的区别 ,因而推测第 46位氨基酸与短链神经毒素对烟碱型乙酰胆碱受体结合功能相关     

平颏海蛇毒磷脂酶A2基因的多样性

通过对平颏海蛇毒腺cDNA文库的随机测序和PCR筛选,分离到3种未曾报道的磷脂酶A2（PLA3）cDNA,分别命名为PLA2－8,PLA2－9,PLA2－384。这些cDNA均含有完整的读码框（长度分别为456bp、438bp和438bp）,编码含27个氨基酸残基的信号肽和长度分别为4．8、7．8和8．4。氨基酸序列分析和二级结构预测表明,3种PLA2均属I类磷酯酶A2家族,其中PLA2－8与来自澳大利亚虎蛇Notechis scutatus scutatus的PLA2有81％的同源性;而PLA2－9和PLA2－384则与来自海蛇Enhydrina schistosa的肌毒PLA2有90％的同源性,这不仅预示着他们在功能上可能存在某些相似性,也反映出平颏海蛇PLA2的结构多样性。这组海蛇PLA2同功酶基因的成功克隆为进一步揭示PLA2的结构与功能关系及的分子机制提供了新的信息。