Indole-3-acetic acid biosynthesis in <Emphasis Type="Italic">Aciculosporium take</Emphasis>, a causal agent of witches' broom of bamboo

 Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002     

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.     

壳聚糖对黄瓜种子萌发和生长发育的影响

研究了壳聚糖对黄瓜种子萌发和生长发育的影响。结果表明，壳聚糖能促进种子萌发，改善根系的发育，增强超微弱发光强度和过氧化氢酶的活性，最适宜浓度为0.1%和0.05%。     

寄主植物对桃蚜羧酸酯酶和乙酰胆碱酯酶的诱导作用

在１９９５～１９９６年研究了寄主植物对桃蚜［Ｍｙｚｕｓｐｅｒｓｉｃａｅ（Ｓｕｌｚｅｒ）］羧酸酯酶（ＣａｒＥ）和乙酰胆碱酯酶（ＡＣｈＥ）的诱导作用。在试验的甘蓝、茄子和桃树３种寄主植物中，取食甘蓝的桃蚜种群ＣａｒＥ和ＡＣｈＥ活性最高，取食茄子和桃树的桃蚜种群ＣａｒＥ活性没有明显不同，而ＡＣｈＥ活性取食茄子的桃蚜种群明显高于取食桃树的种群。ＣａｒＥ与底物的亲和力是桃树＞茄子＞甘蓝，而ＡＣｈＥ与底物的亲和力则是甘蓝＞茄子＞桃树。ＡＣｈＥ与毒扁豆碱的双分子速率常数（Ｋｉ）值大小顺序为甘蓝＞桃树＞茄子     

三种外检植物病毒的灭活处理

番茄环斑病毒（ＴｍＲＳＶ），烟草环斑病毒（ＴＲＳＶ），南芥菜花叶病毒（ＡｒＭＶ）的病汁液和ＰＥＧ粗提纯液，经适宜温度或甲醛处理，均丧失侵染性而有抗原性。ＴｍＲＳＶＰＥＧ粗提纯液经６０℃（水浴）处理１０分钟或２８℃７天，ＴＲＳＶ粗提纯液置２５℃一个月，Ａｒ－ＭＶ在４０℃７天条件下均可做为阳性对照的灭活处理的最佳方案。可保存抗原性在７～１２月以上。为了防止危险性检疫病毒的侵入，对入境种苗进行检疫，需建立快速、准确、标准化检疫程序，而在血清学快速诊断试验中，提供阳性对照，对提高判断准确率是必要的。因此，为了解决在诊断试剂中提供阳性对照但又不能使其检疫性病毒人为扩散这一重要问题，我们在研究三种外检病毒（ＴｍＲＳＶ，ＴＲＳＶ，ＡｒＭＶ）的检验技术的同时，又进行了一些灭活试验，用化学和物理方法钝化病毒，使其失去侵染性而保持抗原性，并应用于酶联诊断试剂盒中，本文报道了初步试验结果     

山羊传染性胸膜肺炎支原体和绵羊肺炎支原体对抗菌药物敏感性的研究

测定了环丙沙星、氧氟沙星、单诺沙星、红霉素、罗红霉素、泰乐菌素、泰妙菌素、四环素等8种药物对羊肺炎支原体两个标准株Y-98和Y-goat的体外抑菌浓度以及红霉素与氧氟沙星、泰乐菌素对Y-goat和四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏作用.结果表明,这8种抗菌药物对Y-goat和Y-98的MIC(μg/mL)分别为:环丙沙星0.223、0.002 23,氧氟沙星0.281、0.014 0,单诺沙星0.136、0.014 0,红霉素0.021 8、无效,罗红霉素0.032 7、无效,泰乐菌素0.042 2、0.039 0,泰妙菌素0.021 7、0.052 0,四环素0.195、0.052 0.红霉素与氧氟沙星的联合药敏指数为1,是相加作用;红霉素与泰乐菌素对Y-goat的联合药敏指数为1.5,是无关作用;四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏试验指数均为0.375,是协同作用.     

金顶侧耳与黄白侧耳性亲和特性的研究

研究了金顶侧耳 (Pleurotuscitrinipileatus)与黄白侧耳 (Pleurotuscornucopiae)的性亲和性及其杂交菌株的特性 ,结果表明 :金顶侧耳与黄白侧耳相互亲和 ;获得的 2株杂交菌株CC - 1、CC - 2的生长最适宜温度分别为 2 3 38～ 2 4 6 2℃、 2 3 6 1～ 2 4 19℃ ,而其亲本金顶侧耳 (0 5 79)和黄白侧耳 (MH0 0 30 1)交配型基准株的最适宜生长温度分别为 2 4 0 3～2 6 37℃、 2 4 2 7～ 2 6 33℃ ,杂交菌株的最适宜生长温度均低于亲本菌株     

桃树不同生长型及其研究进展

生长型是桃树重要的树体特征,是控制树体大小的遗传因素,与栽培关系密切。综合有关文献介绍了桃树的紧凑型、半矮化型、矮化型、柱型、直立型、短枝型、垂枝型等生长型资源及不同生长型在遗传、形态特征、生理、栽培等方面的研究进展。紧凑型受单位点显性基因控制,树体开张,分枝角度大,萌芽率及成枝力均高,光透过率较低;半矮化型树体介于普通型和紧凑型之间;矮化型为单基因隐性性状,节间极短,树体矮小,叶片密度大,光透过率低;柱型枝条分枝角度小,冠幅小,叶面积指数大;直立型介于柱型和普通型之间;短枝型能形成较多的短果枝,并以短果枝结果为主;垂枝型枝条披散下垂,枝条弯曲。不同生长型之间在氮素、干物质分配和内源激素水平上也存在一定的差异。紧凑型、矮化型由于树冠密度大,光透过率低而在应用上受到限制,直立型和柱型因适应了高密度栽培而更受人们的重视。针对目前存在的生长型分类与命名问题,作者认为应首先考虑节间长度,其次为萌芽率、成枝力等,然后考虑的是枝条的分枝角度。     

Functional heterogeneity in resources within landscapes and herbivore population dynamics

Large mammalian herbivores are notorious for their propensity towards population irruptions and crashes, yet many herbivore populations remain relatively stable. I explore how resource heterogeneity within landscapes dampens population instability, using a metaphysiological modelling approach considering patch state distributions. Resource heterogeneity is functionally stabilizing through spreading consumption away from preferred resources before these become critically depleted. Lower-quality resources act as a buffer against starvation during critical periods of the seasonal cycle. Enriching resource quality is destabilizing, even if patch diversity is maintained, because food quantity then becomes the limitation. The potential consequences of landscape fragmentation are explored using the Serengeti ecosystem, characterised by broadscale resource gradients, as a hypothetical example. Further insights provided by the model are illustrated with specific examples concerning the effects of patch scales and waterpoint distribution. A metaphysiological modelling approach enables the basic consequences of landscape heterogeneity to be distinguished from further effects that may arise from specific patch scales and configurations, without the distracting detail of spatially explicit models.     

Comparison of different conditions inducing embryonic stem cells

AIM: To evaluate the different conditions inducing mouse embryonic stem cells (ESC) in vitro to differentiate into cardiomyocytes. METHODS: BRL conditioned medium was used to promote the growth of ESC and maintain them in an undifferentiated state. During the inducing process, retinoic acid (RA), DMSO, activin-A and TGF-β₁ were used as inducing reagents, and made up six kinds of differentiating medium. Then a three-step method inducing ESC cultured in hanging drops, in suspension and in plating was used to induce the differentiation of ESC. RESULTS: ESC were induced in vitro to differentiate into cardiomyocytes. Of all groups, the highest differentiating rate was observed in the group induced by activin-A (20 μg/L) and TGF-β₁ (2 μg/L). CONCLUSION: The inducing conditions including activin-A (20 μg/L) and TGF-β₁ (2 μg/L) is very valuable in inducing ESC differentiation into cardiomyocytes.