贵州的石杉属植物

贵州的石杉属植物王筱英摘要＊本文介绍贵州产的９种石杉,内含１新种,即雷山石杉ＨｕｐｅｒｚｉａｌｅｉｓｈａｎｅｎｓｉｓＸ．Ｙ．Ｗａｎｇ;同时还编有分种检索表、生境和地理分布。关键词石杉属,贵州ＮＯＴＥＳＯＮＨＵＰＥＲＺＩＡＢＥＲＮＨ．ＩＮＧＵＩＺＨＯＵ...     

油菜菌核病菌生理生态研究

通过试验分析,结果得出,油菜菌核病菌生长温度范围在0～34℃之间,23℃以下菌丝生长速度与温度呈正相关,25℃以上则呈负相关,23～25℃最适宜,菌丝和菌核致死温度分别为45℃和75℃．该菌对酸碱度适应范围很广,PH1～14范围内只在PH_1条件下不能生长,其最适PH值为5～6。病菌利用铵态氮源能力最强,硝态氮源次之,不能利用亚硝态氮;对氨基酸利用能力以精氨酸最强,其次是酪氨酸、天门冬氨酸和谷氨酸,赖氨酸最差。植株内精氨酸和赖氨酸比值大的白菜型油菜“黄鳝籽”病情扩展最快。     

南极长城站微生物区系调查

1992～1993年的夏季,对南极中国长城站的陆地进行了微生物区系的现场调查。先后采集各种类型上样多个。其中对有生态意义的25个样进行了不同类型微生物的分离和计数;中温培养下每克湿土壤菌量为10²～10⁶,用马丁培养基对真菌进行分离培养和计数,每克湿土含菌量为10²～10⁴;0℃下分离计数,发现低温下微生物的数量较中温的多,每克湿土壤含菌为10³～10⁶。对该地区烃氧化菌进行了特别调查,以长城站为中心东西宽0．4Km,南北长1Km的范围内烃氧化菌发育最为活跃,但距长城站距离越远,烃氧化菌数量越少。     

恒河猴、懒猴和树鼩的短时空间记忆功能与前额叶背侧部进化水平的相关性(英文)

本文研究探讨了进化地位不同的三种动物的短时空间记忆功能及其与前额叶背侧部进化水平的相关性。结果表明,在延缓反应作业中,经1000次训练后,7只恒河猴对空间位置的记忆时间平均为7.7±3.2min,懒猴为3.8±0.44min,而树鼩即使在延缓时间几乎为零秒的延缓反应中,其正确反应率也未达到90％标准。一种延缓时间仅测试一个单元,即不经训练的实验表明,恒河猴在延缓期为“0”—5min的各测试单元中,正确反应率稳定在80％以上;懒猴在延缓时间为“0”—4min的各测试单元中,平均正确反应率与恒河猴无明显差异,而当延缓时间增加到5min时,在延缓反应作业中取得的成绩显著下降;树鼩在延缓时间为1—5min的作业中取得的正确反应率在70％以下。3种动物在视觉辨别学习作业中却无明显差异。形态学研究表明,灵长类大脑前额叶的面积和结构的复杂性在进化过程中逐渐增大,如恒河猴大脑前额叶的表面积占大脑半球表面积的11.5％(Brodmann,1929),其内颗粒层发达,背侧部明显凸起,主沟区发达;懒猴的前额叶表面积占其大脑半球表面积的8.3％,背侧部凸起不显著,主沟未形成,额极内颗粒层分化明显,背侧部的内颗粒层较内侧部的发达程度差(Sanides,1967);树鼩的前额叶表面积占7.5％,额极的内颗粒层分化不明显,为非颗粒化区,此区之后为颗粒区     

CSE1 and CSE2, two new genes required for accurate mitotic chromosome segregation in Saccharomyces cerevisiae.

By monitoring the mitotic transmission of a marked chromosome bearing a defective centromere, we have identified conditional alleles of two genes involved in chromosome segregation (cse). Mutations in CSE1 and CSE2 have a greater effect on the segregation of chromosomes carrying mutant centromeres than on the segregation of chromosomes with wild-type centromeres. In addition, the cse mutations cause predominantly nondisjunction rather than loss events but do not cause a detectable increase in mitotic recombination. At the restrictive temperature, cse1 and cse2 mutants accumulate large-budded cells, with a significant fraction exhibiting aberrant binucleate morphologies. We cloned the CSE1 and CSE2 genes by complementation of the cold-sensitive phenotypes. Physical and genetic mapping data indicate that CSE1 is linked to HAP2 on the left arm of chromosome VII and CSE2 is adjacent to PRP2 on chromosome XIV. CSE1 is essential and encodes a novel 109-kDa protein. CSE2 encodes a 17-kDa protein with a putative basic-region leucine zipper motif. Disruption of CSE2 causes chromosome missegregation, conditional lethality, and slow growth at the permissive temperature.     

我国半乳甘露聚糖胶资源利用前景初探

半乳甘露聚糖植物胶加工是我国70年代中期兴起的新兴产业。本文从我国植物资源发展的角度。重点论证了瓜尔豆（Cyanopsis tetragonoloba（L.）Taubert.）、田菁（Sesbania cannabina(Retz.)Pers.)、胡芦巴（Trigonella foenum-graecum L.）的生产情况,认为胡芦巴适应性强、产量高、易于机械化大面积种植与轮作,并具有改良土壤以及经济效益好等优势。因此,发展半乳甘露聚糖胶资源,大量种植胡芦巴是最好的选择。     

人体肠道细菌寡营养培养组条件的优化研究

【目的】探讨寡营养对人体肠道细菌培养组的条件。【方法】通过稀释富集培养基、固体平板和增菌肉汤培养基成分获得寡营养培养基。对健康人粪便样本分别用原液(0)、5、10、20、30和40倍稀释的富集培养基(添加羊血和瘤胃液的血培养瓶)连续增菌,在不同时间点(第0、3、6、9、15、27、30天)吸取增菌液,用YCFA (yeast casitone fatty acid)固体培养平板分离菌落;用YCFA增菌肉汤增菌后再次挑取单菌落,利用基质辅助激光解吸/电离飞行时间(matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,MALDI-TOF)质谱和16S rRNA基因测序鉴定菌株。通过比较上述6种寡营养条件分离肠道菌群的效果,选取富集培养基原液、稀释10倍和30倍这3 种条件下分离效果较好的富集条件,与同样稀释倍数条件的固体平板和增菌肉汤分别组合成9种培养基条件,进一步优化肠道菌群的培养组条件。【结果】在6种寡营养富集培养基中,未稀释(原液)、10 倍和30倍稀释的富集培养基分离细菌的种类比其他...     

Genomic insights into selection for heterozygous alleles and woody traits in Populus tomentosa

Heterozygous alleles are widespread in outcrossing and clonally propagated woody plants. The variation in heterozygosity that underlies population adaptive evolution and phenotypic variation, however, remains largely unknown. Here, we describe a de novo chromosome-level genome assembly of Populus tomentosa, an economic and ecologically important native tree in northern China. By resequencing 302 natural accessions, we determined that the South subpopulation (Pop_S) encompasses the ancestral strains of P. tomentosa, while the Northwest subpopulation (Pop_NW) and Northeast subpopulation (Pop_NE) experienced different selection pressures during population evolution, resulting in significant population differentiation and a decrease in the extent of heterozygosity. Analysis of heterozygous selective sweep regions (HSSR) suggested that selection for lower heterozygosity contributed to the local adaptation of P. tomentosa by dwindling gene expression and genetic load in the Pop_NW and Pop_NE subpopulations. Genome-wide association studies (GWAS) revealed that 88 single nucleotide polymorphisms (SNPs) within 63 genes are associated with nine wood composition traits. Among them, the selection for the homozygous AA allele in PtoARF8 is associated with reductions in cellulose and hemicellulose contents by attenuating PtoARF8 expression, and the increase in lignin content is attributable to the selection for decreases in exon heterozygosity in PtoLOX3 during adaptive evolution of natural populations. This study provides novel insights into allelic variations in heterozygosity associated with adaptive evolution of P. tomentosa in response to the local environment and identifies a series of key genes for wood component traits, thereby facilitating genomic-based breeding of important traits in perennial woody plants.     

Artificial nanovesicles for dsRNA delivery in spray-induced gene silencing for crop protection

Spray-induced gene silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of RNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for RNA encapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP and DODMA, and examined for their ability to protect and deliver double stranded RNA (dsRNA). All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome RNA instability in SIGS for crop protection.