Functional genomics of maize submergence tolerance and cloning of the related gene Sicyp51

In the middle and lower Yangtze River area, the major corn-growing region of South China, seasonal rainfall greatly affects maize plantation. Maize seed-lings meet with excessive precipitation and low tem-perature in spring, and when they grow up to begin flowering, they usually encounter Mei-yu storm ac-companied by hot days. At the same time, bad irriga-tion system and a higher level of underground water cause waterlogging, which further leads to yield losses. In order to reveal the molecu…     

分子生物学数据库及相关软件的开发利用

生物大分子序列和结构测定技术的完善和应用,使核酸及蛋白质序列数据库及蛋白质结构数据库迅速增长。面对不断增长的分子生物信息,很多生物学工作者又在此基础上构建了具有特殊生物学意义和专门用途的二次数据库,使得数据库的内容和种类更加丰富和具体,为生物学各个领域的深入研究提供了坚实的信息基础。由法国生物信息研究中心Ｉｎｆｏｂｉｏｇｅｎ提供的生物数据库目录ｄｂｃａｔ〔１〕可以使用户对目前世界各地提供的分子生物信息数据库有一个详尽的了解。ｄｂｃａｔ本身也是一个具有一定数据格式的数据库,按ＤＮＡ、ＲＮＡ、蛋白质…     

MJD基因CAG不稳定性扩增与临床研究

为了解Machado-Joseph病(MJD)基因突变及临床的神经电生理特点, 对16个诊断为遗传性小脑性共济失调(SCA)家系的45例病人及30例家系的“正常”人作MJD基因突变分析,检出MJD基因的病人行肢体运动及感觉神经传导速度(MCV及SCV)、脑干诱发电位(BAEP),视觉诱发电位(VEP)的检查。结果检出10个家系25例病人及1例症状前18岁女孩有MJD基因突变,CAG三核苷酸重复73～79次,异常等位基因片段长380～402bp,均为杂合子; 正常人CAG三核苷酸重复18～40次,等位片段长200～270bp,电生理发现MJD的SCV减慢比MCV明显,而下肢的MCV、SCV又较上肢明显,BAEP、VEP均有不同程度的潜伏期延长或波的异常;MJD的父亲遗传早于母亲,进展也较块,临床以小脑性共济失调为突出症状,其次为构音障碍、突眼等,肌肉萎缩仅见于晚期病人;MRI示小脑萎缩较明显,脑干萎缩并不严重,未见明显的颈髓萎缩。 Abstract:　To investigate the gene mutation of clinical and neuroelectrophysiological characteristics in Machado-Joseph disease(MJD). The gene mutation was detected in 45 patients diagnosed as spinocerebellar ataxia(SCA) and 30 “healthy relatives”. Brain stem evoked potentials(BAEP), visual evoked potentials(VEP) and motor conduction velocity (MCV) and sensory conduction velocity (SCV) were performed on MJD. Gene mutations were detected in 25 patients and a 18-year-old girl among 16 families. Trinucleotide repeats of CAG were 73～79. The fragments of abnormal alleles were 380～402bp, and all patients were heterozygous. The copy numbers of normal alleles were 18～40, fragments from 202～270bp. SCV reduction was much obvious compared to MCV, MCV and SCV in lower limb ?ere much more slow than that in upper's. BAEP, VEP were also delayed in latency. The anticipation in parental sex bias were much more obvioius than that in matental's. Cerebellar ataxia was most severe, the next were dysarthria and bulging eyes. Amytrophy was seen only in bed ridden patients. Cerebellar atrophy was more severe than brain stem, cord atrophy was n't observed in all MJD.     

Effects of Zn2+ and Cu2+ on loach ovaries and ova development

This study compared the accumulation of Zn2+and Cu2+in the ovaries and ova of loaches under different concentrations of Zn2+(1.00, 2.50 and 5.00 mg/L respectively) and Cu2+(0.10, 0.25 and 0.50 mg/L respectively). The results showed that both Zn2+and Cu2+accumulated in the ovaries, and that the relationship between accumulation and time was linear over 20 days of exposure. The accumulation of the metals in ovaries was closely related to the concentration of exposure in the solutions(P<0.05), and was obviously affected by the time and doses. However, the Cu2+concentration was significantly higher than Zn2+(P<0.05). The development level of ova in the ovaries also correlated with the concentration and exposure period in the Zn2+and Cu2+solutions.     

In vivo skin penetration and metabolic path of quantum dots

The skin is the largest organ of the body and is a potential route of exposure to sunscreens and cosmetics containing nanoparticles;however,the permeability of the skin to these nanoparticles is currently unknown.In this paper,we studied the transdermal delivery capacity through mouse skin of water-soluble CdSeS quantum dots(QDs) and the deposition of these QDs in the body.QD solution was coated onto the dorsal hairless skin of male ICR mice.Fluorescence microscopy and transmission electron microscopy(TEM) were used to observe the distribution of QDs in the skin and organs,and inductively coupled plasma-mass spectrometry(ICP-MS) was used to measure the 111Cd content to indicate the concentration of QDs in plasma and organs.Experimental results indicate that QDs can penetrate into the dermal layer and are limited to the uppermost stratum corneum layers and the hair follicles.Through blood circulation,QDs deposit mostly in liver and kidney and are difficult to clear.111Cd concentration was greater than 14 ng g-1 in kidney after 120 h after 0.32 nmol QDs was applied to a mouse.These results suggest that QDs have in vivo transdermal delivery capacity through mouse skin and are harmful to the liver and kidney.     

Spontaneous modulation of a dynamic balance between bacterial genomic stability and mutability: roles and molecular mechanisms of the genetic switch

Bacteria need a high degree of genetic stability to maintain their species identities over long evolutionary times while retaining some mutability to adapt to the changing environment.It is a long unanswered question that how bacteria reconcile these seemingly contradictory biological properties.We hypothesized that certain mechanisms must maintain a dynamic balance between genetic stability and mutability for the survival and evolution of bacterial species.To identify such mechanisms,we analyzed bacterial genomes,focusing on the Salmonella mismatch repair(MMR)system.We found that the MMR gene mutL functions as a genetic switch through a slipped-strand mispairing mechanism,modulating and maintaining a dynamic balance between genetic stability and mutability during bacterial evolution.This mechanism allows bacteria to maintain their phylogenetic status,while also adapting to changing environments by acquiring novel traits.In this review,we outline the history of research into this genetic switch,from its discovery to the latest findings,and discuss its potential roles in the genomic evolution of bacteria.