玉米叶片受新月弯孢菌侵染后的细胞病理学变化

 本文利用透射电子显微镜技术与细胞化学技术研究了玉米叶片受弯孢菌侵染后的超微结构和细胞壁的组成成份变化。透射电镜观察发现,病菌侵入后,菌丝先在寄主细胞间扩展,随着寄主细胞病变、坏死,菌丝可进入寄主细胞形成胞内菌丝。随病菌侵入和在寄主体内扩展,寄主细胞先后发生了一系列的超微结构变化,叶绿体、液泡等细胞器解体,出现质壁分离现象,并最终解体、坏死、变形。细胞化学标记定位发现,受侵寄主细胞壁中纤维素、木聚糖和果胶质的标记密度明显低于未接种的健康组织,表明细胞壁降解酶(如纤维素酶、木聚糖酶和果胶酶)的产生与病菌侵染和致病过程密切相关。     

红掌细菌性疫病的病原菌初步鉴定

 在云南西双版纳的红掌上发现一种由细菌侵染引起的病害,从叶片的病组织上分离到具有致病性的杆状细菌,将分离的病原菌接种于健康的红掌上,表现出与田间一致的症状。感病初期在叶缘或叶脉间出现水渍状小点,后期病斑多呈棕褐色至黑色坏死,病健交界处多呈黄色。从接种发病的病斑与田间标样上分离的病原菌菌落形态完全相同。通过菌株的培养性状、常规生理生化特性及透射电镜下菌体形态观察结果,将病原菌初步鉴定为黄单胞菌属(Xanthomonas)。BIOLOG鉴定和致病性测定结果进一步鉴定病原菌为地毯草黄单胞菌花叶万年青致病变种Xanthomonas axonopodis pv. dieffenbachiae(Xad)(McCulloch & Pirone) Vauterin et al.     

草酸对重寄生真菌盾壳霉分生孢子萌发和菌丝生长的影响

 本文研究了草酸对核盘菌的重寄生真菌盾壳霉(Coniothyrium minitans)分生孢子萌发和菌丝生长的影响。结果表明:草酸对盾壳霉分生孢子萌发没有明显促进作用,在酸碱性非缓冲基质(水琼脂)和酸碱性缓冲基质中,抑制盾壳霉分生孢子萌发的最低浓度分别为150和700μg/mL。在马铃薯葡萄糖琼脂培养基中,当草酸浓度为100~2000μg/mL时,盾壳霉菌丝能够生长,且浓度为300~500μg/mL的草酸对盾壳霉的菌丝生长具有明显的促进作用。在以草酸为唯一碳源的合成培养基中,在酸碱性非缓冲的条件下,当草酸浓度为100~2000μg/mL时,盾壳霉菌丝能够生长,且草酸浓度为500μg/mL时对盾壳霉菌丝生长具有促进作用,而当草酸浓度为2500μg/mL时,盾壳霉菌丝则停止生长。在酸碱性缓冲的合成基质中,草酸浓度为100~4000μg/mL时,盾壳霉菌丝能够生长,且草酸浓度为1500~2500μg/mL时对盾壳霉菌丝生长具有促进作用。在含草酸钙的混浊培养基(以草酸为唯一碳源)上,盾壳霉菌落区域形成了透明圈。上述结果说明盾壳霉能忍耐一定浓度的草酸而进行分生孢子萌发及菌丝生长,且这种真菌可能对草酸分子具有分解作用。     

基于GIS的中国小麦条锈病菌越夏区气候区划

 基于多年的气象数据(1980~2001年),首次从制约小麦条锈病菌越夏的温度因子入手,结合寄主小麦因素,利用地理信息系统(Geographical Information System,GIS),对我国小麦条锈病菌越夏区进行较详细的气候区划。本研究从温度条件上明确了全国适合小麦条锈病菌越夏的范围。研究表明,在我国小麦种植区适合小麦条锈病菌越夏的范围很广。其中甘肃、四川、云南、陕西境内适合越夏的地区是连成一片的,甘肃东部除了西边的几个县外其它地方7、8月份最高一旬均温在20~23℃,条锈病菌越夏困难;西藏、青海境内的小麦种植区几乎都适合小麦条锈病菌越夏;贵州境内适合越夏的地区可能和云南越夏区是一个整体。云南适合越夏的地区甚广,且地形复杂,需要进一步调查研究。     

氮素水平对单作和间套作小麦玉米叶片叶绿素含量及品质的影响

以间套作小麦玉米、单作小麦和单作玉米为研究对象,通过田间试验研究了氮素水平对单作和间套作小麦玉米叶片叶绿素及品质的影响。主要结果为:在同一施氮水平下,间套作小麦旗叶叶绿素含量大于相应单作;单作和间套作小麦开花期旗叶叶绿素含量和蛋白质含量、沉淀值之间都呈显著正相关(r分别为0.960*,0.948*,0.968*,0.957*)。在相同施氮水平下,单作玉米叶绿素含量高于相应间套作玉米;单作和间套作玉米孕穗期叶绿素含量与其蛋白质含量之间也呈显著正相关(r分别为0.861*和0.870*)。     

山杏幼苗水分生理生态特性及凋萎湿度的研究

对山杏幼苗进行 3种施水量的水分培养和干旱处理。结果表明 :随施水量的减少 ,叶片的净光合速率、蒸腾速率、气孔导度和水分利用效率等指标都随之下降 ,叶片温度提高。 40 9.2和 1 89.2 mm施水量对山杏幼苗各项指标的影响呈显著差异 ,而 40 9.2和 32 1 .2 mm之间与 32 1 .2和 1 89.2 mm之间均无差异。随土壤干旱的加剧 ,山杏幼苗叶片的蒸腾速率和水势与土壤含水量呈规律性变化 ;当干旱持续 39天时 ,1 .44%的土壤含水量可视为山杏幼苗的凋萎湿度     

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.     

导致一例强沙尘暴的若干天气因素的观测和模拟研究

利用常规观测资料和数值模拟方法对影响2001年4月6-8日强沙尘暴天气发生的若干天气因素进行了研究。结果表明在本次“锋面气旋型”沙尘暴过程中,气旋冷锋是引发强沙尘暴的主要系统,冷锋过境对沙尘暴的触发作用远强于气旋发展。冷锋的动力学特点决定其常与强沙尘暴伴随。影响沙尘暴的诸多天气因素中,影响地面大风形成的有效动量下传机制为高空急流下沉支使高空动量下传至对流层中层,其下方形成的深厚混合层使这一动量继续下传到地面。“混合层”从本质上反映了有利沙尘暴形成的大气层结特征,深厚混合层的是否形成很大程度决定着沙尘暴的强度。本次过程深厚混合层的形成是长时间地面加热的结果,这也是特强沙尘暴仅发生在内蒙古中部偏北地区而不是下垫面条件更为适宜的内蒙古西部的原因。混合层空气的平流对内蒙古中部偏北地区深厚混合层的形成具有相当的贡献,其影响程度与地形分布密切相关。地面热通量试验表明地面加热对冷锋过境时上升运动的强度、深厚混合层形成、高空动量下传等具有重要影响,并因此影响沙尘暴强度。     

南昌市郊常见花卉炭疽病初步鉴定

本文对南昌市郊常见花卉炭疽病病原进行了初步鉴定。结果表明，鹅掌柴炭疽病等8种炭疽病病原为胶孢炭疽菌（Colletotrichum gloeosporioides(Penz.Sacc.)，月季炭疽病等5种病害病原为新报道的炭疽病，病原种的归属有待进一步确定。     

Effect of EGFP gene transfection on the cell cycle distribution of primary cultured human chondrocytes

AIM: To investigate the effect of enhanced green fluorescence protein (EGFP) gene transfection on the cell cycle distribution of primary cultured human chondrocytes in order to establish a tracking method of cultured human nasoseptal chondrocytes. METHODS: pEGFP-N1 plasmid was amplified in E.coli, and purified by high purity kit. Primary cultured human chondrocytes,which were initially obtained from the nasoseptal cartilage, were cultured in vitro and transferred with pEGFP-N1 by means of electroporation with Amaxa nucleofector device. Transfering process and transient expression were evaluated by laser scanning confocal microscope (LSCM), the transfer efficiency and the cell cycle distribution were evaluated by flow cytometry. RESULTS: There was significant expression of EGFP at 24 h after transferring. The transfection efficiency of pEGFP-N1 into primary cultured human chondrocytes reached 35.37％ at 48 h. It didn't affect the process of cell adherance and had no effect on the cell cycle distribution. CONCLUSION: Primary cultured human chondrocytes, which were transfected with pEGFP, are alive in vitro, and the transferring process doesn't affect the cell cycle distribution. These results suggest that pEGFP-N1 is an ideal transient expression vector for primary cultured human chondrocytes and it might be a well tracer in construction tissue engineered cartilage.