组织培养条件下苹果Ty1-copia类逆转座子的转录活性

研究了苹果基因组中Tyl—copia类逆转座子的转录活性、多样性及其甲基化水平。在培养基MS＋2，4-D2mg／L＋BA0．2mg／L＋NAA0．5mg／L上诱导了1个月的愈伤组织中用RT—PCR方法检测到了270bp的目的条带，而对照、继代组培苗和不含2，4-D的愈伤中均没有目的条带的扩增，说明一定浓度的2，4-D可以诱导苹果中Tyl—copia类逆转座子的表达活性。将目的条带回收、克隆和测序后进行分析：所克隆的21条序列虽都为Tyl-copia类逆转座子逆转录酶保守序列，但存在很大的异质性，21个克隆的核甘酸序列变化范围为196—290bp；翻译成氨基酸后存在缺失、插入、移框和终止密码子突变，7个克隆在氨基酸保守序列‘SLYGLKQ’处有1—2氨基酸位点的突变，说明这些序列对应的逆转录酶多数可能已失去了其原有功能。将21条序列进行聚类分析，除ART20外，其它克隆可聚为3类，并分别与GenBank上某些物种的相应序列同源性很高，表明在不同物种间可能存在逆转座子的横向传递作用。甲基化试验表明苹果基因组内Tyl-copia类逆转座子甲基化水平高。这些都表明Tyl-copia类逆转座子对苹果基因型的多样性及基因组的进化具有重要意义。     

柑橘裂皮病类病毒的一步RT-PCR法检测及其在甜橙体内的分布

柑橘裂皮病是由柑橘裂皮病类病毒(Citrusexocortisviroid,CEVd)引起的一种重要的柑橘病害。分别采用快速微量核酸提取法和SDS-KAc抽提法在表现症状的Etrog香橼中提取核酸,采用一步RT-PCR法对CEVd进行检测,结果显示SDS-KAc法可以消除带毒样品中非特异性条带。从嫁接接毒的铜水72-1锦橙植株的接穗部取嫩叶、老叶、皮,从砧木部茎杆上取老皮以及根皮分别提取总核酸进行RT-PCR检测,分析CEVd在甜橙体内的分布情况。初步检测结果表明在接穗的嫩叶、老叶、皮,砧木部茎杆的老皮和根皮上都可以检测到CEVd,以接穗部叶和皮检出稳定性高。     

母猪卧向行为学的观察

本文通过2个试验对母猪在分娩圈和分娩栏中的卧向行为进行了观察,试验一中, 选择10头大白(Yorkshire)经产母猪作为观察对象,试验二中分别选择10头大白(Yorkshire) 经产母猪和10头长白(Landrace)经产母猪作为观察对象。观察采用瞬时记录方法,每周观察 三次,隔日观察,每天上午、下午各观察一次,每次3 h,每次观察间隔5 min。观察中发现,母猪 卧向以向外为主。分娩栏(四周是栏杆)中的母猪以选择卧向外(向北)为主,其次是卧向内(向 南),卧向左和卧向右最少且差异不显著,上栏前和下栏后差异不显著。分娩圈(四周是墙壁)中 母猪以选择卧向外为主,卧向内最少,卧向左和卧向右差异不显著。长白母猪比大白母猪选择 卧向外的多,妊娠阶段比哺乳阶段选择卧向外的多。     

菌根与植被恢复

菌根不仅可促进植物的营养吸收、生长发育、抗病、抗逆,而且在保持良好的土壤结构、控制水土流失方面具有直接的作用。在我国西北许多地区,菌根菌与植物间的共生关系已被中断,要恢复该地区的植被,治本的方法应是重建植物与菌根菌的共生关系,形成健康的生态系统。文中还提出了菌根技术在植被恢复中的应用策略。     

Selection and amplification of the liver stem cell subset from rat bone marrow cells with a medium containing cholestatic serum in vitro

AIM: To explore the feasibility of direct separat and selective enlargement of the bone marrow-derived liver stem cells (BDLSC) from bone marrow cells with a culture system containing cholestatic serum in vitro. METHODS: Bone marrow cells of rats were cultured with selective media containing 2%, 5%, 7% and 10% cholestatic rat serum, respectively. The BDLSC were then induced to proliferate with the addition of hepatocyte growth factor (HGF) on the firth day. BDLSC were characterized using immunocytochemistry and RT-PCR for lineage markers, glycogen staining and urea synthetic assay for functions 2 weeks later. RESULTS: Bone marrow cells were unble to form colony in the presence of 2% cholestatic serum and apopotosis appeared gradually in 7% or 10% cholestatic serum. The BDLSC survived in the medium containing 5% cholestatic serum while the other types of cells did not. The survival cells proliferated with a high speed during the second week and then formed hepatocyte-like colony-forming units (H-CFU). Cells in the H-CFU expressed the characteristic proteins of fetal hepatocytes. Furthermore, they had glycogen storage and urea synthesis functions, two of the critical features of hepatocytes. CONCLUSION: The selective micro-environment effectively selected BDLSC from the bone marrow cell, and will be a new way to provide an abundant source of donor hepatocytes for clinical cell therapy.     

Effect of mutant β-catenin gene on the proliferation of hepatocytes

AIM:The β-catenin is a key molecule in the Wnt signal pathway, which plays a critical role in normal development and tumorigenesis. However, the mechanisms of the β-catenin on the cell growth control are still not completely defined. The aim of this study was to test the hypothesis that the mutant β-catenin may regulate the hepatocyte proliferation. METHODS: The immortalized murine hepatocyte cell line, AML12, was used for this study. A plasmid that contain mutant β-catenin S33Y was transfected into the AML12 cells and a stable cell line AML12S33Y was established. The cell growth property of this cell line and the parental cell were compared by flow cytometry analysis and direct cell count. The cells were also tested for the ability to form soft agar colonies, and the ability to form tumors in the severe immune deficient mice (SCID). RESULTS:1. The mutant β-catenin containing cell line AML12S33Y has higher proliferating index compared with the parental AML12 cells (P<0.01), suggesting that mutant β-catenin promotes cell growth. 2. The mutant β-catenin cells formed small colonies in soft agar after 4 weeks of culture, but did not generate tumor in SCID mice. CONCLUSION:The mutant β-catenin promotes liver cell growth.     

Powdery Mildew of Prairie Gentian: Characteristics,Molecular Phylogeny and Pathogenicity

In March 1999, we found prairie gentian (Eustoma grandiflorum) infected with powdery mildew in a greenhouse in Oita Prefecture, Japan. Morphological observation revealed that the causal fungus belongs to the mitosporic genus Oidium subgenus Pseudoidium [teleomorph: Erysiphe sensu Braun and Takamatsu (2000)]. Precise taxonomic position of the fungus, however, is uncertain due to lack of the perfect stage. We determined the nucleotide sequence of the rDNA ITS region of the fungus. Comparison of the sequence with those obtained from DNA databases of this fungal group revealed that the sequence is identical to those of powdery mildews from garden four-o'clock (Mirabilis jalapa) and broad bean (Vicia faba). Inoculation of an isolate from garden four-o'clock caused mildew on prairie gentian and broad bean, suggesting that the prairie gentian mildew originates from garden four-o'clock or broad bean. Molecular phylogenetic analysis indicated a close relationship of this fungus to Erysiphe baeumleri on Vicia spp. and E. trifolii on Trifolium pratense. From these results, we propose that prairie gentian mildew diverged from a Fabaceae-parasitic ancestor. Received 14 March 2002/ Accepted in revised form 28 May 2002     

区域旅游资源开发定位研究——以内蒙古赤峰市为例

区域旅游资源开发是发展区域旅游的基础 ,开发的定位研究有助于为一地旅游业的发展指明方向。本文从区域角度和空间经济一体化思想出发 ,以赤峰市为例 ,通过对旅游资源的定量与定性研究 ,得到旅游资源的综合评价图式 ,结合区际分析归纳出赤峰市旅游资源开发利用的方向和层次。从而为区域旅游开发的定位研究进行了一般理论的探讨及例证分析     

几种除草剂药液表面张力、叶面接触角与药效的相关性研究

在除草剂氟磺胺草醚、灭草松和精喹禾灵药液中添加不同浓度的喷雾助剂ABS(十二烷基苯磺酸钠)和JFC ,以温室盆栽法测得各处理抑制杂草的效果,结果表明,在多数情况下添加喷雾助剂可使3种供试除草剂的药效显著提高。     

转Bt基因棉在安庆市大面积种植后害虫发生特点调查

根据调查,转Bt基因棉大面积种植后,棉铃虫、红铃虫发生减轻;棉叶螨发生加重,为害时间延长;甜菜夜蛾、斜纹夜蛾发生面积扩大,为害程度加重。据此初步提出了当地转Bt基因棉害虫防治中应注意的问题和管理对策。