The boundaries and copy numbers of Ti plasmid T-DNA vary in crown gall tumors

Summary The Ti plasmid DNA maintained in octopine-type crown gall tumor lines is variable, but always includes at least part of the Ti plasmid that maps over the region of Hind III fragment 1 of pTi-B6-806. The right-hand boundary of transferred DNA (T-DNA) varies considerably among the three independent tumor lines examined; the left boundary was not located definitively. The T-DNA of two sibling clones of the same tumor line, E1 and E9, appears identical. The copy number of T-DNA in E9 tumor DNA appears higher for the right end (about 30 copies) than for the left end (approximately 1 copy).     

Histological Reassessment of Three Kidneys Originally Described by Richard Bright in 1827-36

Portions of kidney from three patients with renal disease that were originally described by Richard Bright between 1827 and 1836 have been preserved in the Gordon Museum at Guy''s Hospital. Histological study has shown that two cases fall into the current diagnostic category of mesangiocapillary (membranoproliferative) glomerulonephritis. One of these patients had a five-year clinical history and died with chronic renal failure and uraemia. The other patient died after three to four months with a severe nephrotic syndrome. The third patient was a young woman with chronic “phthisis pulmonalis” and renal amyloidosis.     

Ribonucleic Acid Polymerase in Allomyces arbuscula

Three distinct species of ribonucleic acid (RNA) polymerase were resolved from Allomyces arbuscula by diethylaminoethyl-cellulose chromatography and characterized as to ionic strength and divalent cation preference. alpha-Amanitin specifically inhibited enzyme II; neither rifampin nor cycloheximide had any effect on the three enzymes. RNA polymerase was isolated from three stages of the diploid life cycle: the hyphal growth stage, mycelia in the process of forming sporangia, and the mitospores. The same three enzyme species could be resolved from each stage. Thus, there is no evidence from this work that RNA polymerase plays a major role in the control of development.     

SCANNING ELECTRON MICROSCOPY OF ANTHERIDIA AND ARCHEGONIA OF ANEMIA MEXICANA KLOTZSCH

Antheridia and archegonia of the fern Anemia mexicana were viewed with scanning electron microscopy (SEM). The mature antheridium is composed of a cap, ring, and basal cell with spermatozoids inside. The archegonium neck is composed of a neck canal cell surrounded by four rows of neck cells. The ventral canal cell and egg were not observed. The neck bends toward the notched meristem. The neck cells usually are uniform in shape and arrangement, but in some archegonia, shape and arrangement of neck cells was irregular. The apex of these archegonia often appeared swollen because of the random cell arrangement. In the presence of water, the antheridium cap is partially detached and the spermatozoids emerge. At this time, the neck cells open at the end of the archegonium in preparation for fertilization. The basic morphology of the antheridia and archegonia is similar to previous reports, although SEM provides more structural detail and a better three-dimensional visualization of these reproductive structures.     

Plant tumor reversal associated with the loss of foreign DNA

Summary Transformation of plant tissues into crown gall tumors has been associated with the transfer of a portion of a tumor-inducing plasmid (Ti-plasmid) into plant DNA. Various laboratories have regenerated normal-appearing plants from a number of crown gall tumors. This study investigates the fate of the foreign DNA in a series of tissues derived from various parts of a plant regenerated from the tumor BT-37 by Braun and his coworkers. It was found that all the foreign DNA sequences were lost from tissues that had lost all their tumorous traits; whereas the plasmid DNA sequences were still present in tissues that appeared normal but still exhibited tumorous traits when returned to tissue culture media. From these studies it would appear that the presence of the Ti-plasmid sequences in the plant DNA is required for the maintenance of the transformed state. Presented in the Symposium on Gene Transfer, Differentiation and Neoplasia in Plant and Animal Cells at the 30th Annual Meeting of the Tissue Culture Association, Seattle, Washington, June 10–14, 1979. This symposium was supported in part by Grant CA 26748 from the National Cancer Institute, DHEW, and Grant RD-67 from the American Cancer Society.     

犬MC1R基因T105A基因座多态性及 与毛色性状相关性的研究The

为了检测犬MC1R基因T105A基因座的多态性,并分析该多态性与犬毛色表型的相关性,抽取111只外科手术学实验用杂种犬血液并提取DNA,记录毛色表型。采用PCR-RFLP技术,对MC1R基因T105A基因座进行基因多态性分析,并对该基因座DNA进行克隆测序;用二元变量相关分析的统计学方法分析基因座多态性与毛色性状之间的相关性。经PCR-RFLP分析结果表明,T105A基因座序列具有多态性,表现为A、B二个等位基因和AA、AB及BB 3种基因型。A、B等位基因频率分别为72.97%和27.03%,基因杂合度（H）为0.39。基因型AA频率为55.86%,BB为9.91%,AB为34.23%。对T105A多态性片段DNA克隆测序后发现,MC1R基因在编码第105位氨基酸的密码子第一个碱基存在由G到A的单碱基突变,该突变导致第105位氨基酸发生由丙氨酸向苏氨酸的改变。统计分析结果表明MC1R基因T105A基因座的多态性与毛色性状不存在显著的相关性,这可能是由于外科手术学实验用犬是杂种犬,其遗传背景不同所致,尚须在纯种犬群体中进一步研究MC1R基因对毛色的影响。 Abstract: In order to detect the polymorphism of T105A in MC1R gene in dogs and to analyze the relationship between the genetic polymorphisms and phenotypes of dog coat color, the blood samples of 111 cross-breed dogs were taken and their genomic DNAs were extracted. The phenotypes of dog coat color were recorded. The T105A locus of MC1R gene in the canine was detected through the technology of PCR-RFLP. Furthermore, the polymorphic fragments at T105A were sequenced. The relationships between the polymorphism of T105A and coat color trait were analyzed by the statistical methods of bivarate correlation analysis. By the method of PCR-RFLP, the T105A polymorphism was found with two alleles A and B and three genotypes AA, AB and BB. The frequencies of two alleles were 72.97% and 27.03%, respectively. The heterozygosity of T105A locus was 0.39. The frequencies of three genotypes were 55.86%, 34.23% and 9.91%, respectively. According to the results of sequencing, one base change from G to A at the position 105 was found at T105A locus and it altered amino acid at the position 105 from alanine to threonine. According to the statistical analysis, no significant association between the polymorphism of MC1R gene and the coat color was found and the result may be due to the differences of genetic background. Further research on MC1R gene should be done in pure breed dogs.     

Gene-Enzyme Relationships in Histidine Biosynthesis in Bacillus subtilis

Mutants for 9 of the 10 steps in histidine biosynthesis have been isolated and identified by enzyme assay. Each locus has been mapped in relation to the aro cluster and to other histidine loci by deoxyribonucleic acid-mediated transformation. The genes which code for enzymes 3, 6, and 8 of the pathway are linked to the aro cluster. A major histidine linkage group is composed of the genes which specify enzymes 1, 2, 5, 7, and 10. The locus which codes for step 9 of the pathway is unlinked to any other identified his loci. The major histidine cluster is loosely linked to cysB and is unlinked to any of the loci concerned with aromatic amino acid biosynthesis.