Targeted misexpression of a Drosophila opsin gene leads to altered visual function

Drosophila mutants transformed with a chimaeric gene that expresses the ocellar visual pigment in the major class of photoreceptor cells of the retina were used to investigate the properties of this minor pigment. The photoreceptor cells in which this opsin was misexpressed showed new spectral characteristics and physiology.     

Mutational hotspot in the p53 gene in human hepatocellular carcinomas.

Human hepatocellular carcinomas (HCC) from patients in Qidong, an area of high incidence in China, in which both hepatitis B virus and aflatoxin B1 are risk factors, were analysed for mutations in p53, a putative tumour-suppressor gene. Eight of the 16 HCC had a point mutation at the third base position of codon 249. The G----T transversion in seven HCC DNA samples and the G----C transversion in the other HCC are consistent with mutations caused by aflatoxin B1 in mutagenesis experiments. No mutations were found in exons 5,6,8 or the remainder of exon 7. These results contrast with p53 mutations previously reported in carcinomas and sarcomas of human lung, colon, oesophagus and breast; these are primarily scattered over four of the five evolutionarily conserved domains, which include codon 249 (refs 4-9). We suggest that the mutant p53 protein may be responsible for a selective clonal expansion of hepatocytes during carcinogenesis.     

全面培养化学教育师范生实验综合能力--基础化学实验教学的整体改革与实践

介绍了在高师基础化学实验教学改革中,以整体性教育思想为指导,以素质教育为目的,加强学生综合能力培养,努力提高基础化学实验教学质量的实践和认识.     

圣牛之谜──饮食人类学个案研究

肉食禁忌在不同文化中的表现形式各异。印度教的核心教义中有牛崇拜与牛保护的条文，这个世界第二人口大国至今仍把禁止屠宰母牛的条款写入法律，饲养着约两亿头牛。印度人口的增长与自然资源的紧缺是“不杀生”教义的基础，也是印度人不得不放弃吠陀时代的牛肉美味的原因。在现代农业条件下，废除杀牛禁规不会给印度的饮食节制带来大的改进。没有任何一种动物能够像印度瘤牛那样为人的生存提供如此多的贡献。     

N-甲基-3-氮杂双环(3,3,1)壬-9-酮的制备

环己酮、甲胺盐酸盐、3 6%甲醛在冰醋酸中进行Mannich缩合生成N-甲基-3-氛杂双环(3,3,1)壬-9-酮,其中n(环己酮):n(甲胺盐酸盐):n(甲醛)=1:1.2:3,产率为24.4%.     

对中小学体育教学中美育的研究

就中小学体育教学与美育的关系,美育在体育教学中的功能,以及美育的内容和实施等方面的问题进行阐述.旨在有效地指导中小学体育教学的实践活动.     

The DNA sequence, annotation and analysis of human chromosome 3

After the completion of a draft human genome sequence, the International Human Genome Sequencing Consortium has proceeded to finish and annotate each of the 24 chromosomes comprising the human genome. Here we describe the sequencing and analysis of human chromosome 3, one of the largest human chromosomes. Chromosome 3 comprises just four contigs, one of which currently represents the longest unbroken stretch of finished DNA sequence known so far. The chromosome is remarkable in having the lowest rate of segmental duplication in the genome. It also includes a chemokine receptor gene cluster as well as numerous loci involved in multiple human cancers such as the gene encoding FHIT, which contains the most common constitutive fragile site in the genome, FRA3B. Using genomic sequence from chimpanzee and rhesus macaque, we were able to characterize the breakpoints defining a large pericentric inversion that occurred some time after the split of Homininae from Ponginae, and propose an evolutionary history of the inversion.     

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.     

Genomic segmental polymorphisms in inbred mouse strains

By analyzing genomic copy-number differences using high-resolution mouse whole-genome BAC arrays, we uncover substantial differences in regional DNA content between inbred strains of mice. The identification of these apparently common segmental polymorphisms suggests that these differences can contribute to genetic variability and pathologic susceptibility.