The xylanase introns from Cryptococcus albidus are accurately spliced in transgenic tobacco plants

The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells.     

Developmental variation in copper,zinc and metallothionein mRNA in brindled mutant and nutritionally copper deficient mice

The concentrations of copper, zinc and metallothionein-I (MT-I) mRNA were determined in the liver, kidney and brain of the brindled mutant mouse from birth until the time of death. Despite accumulation of copper in the kidney of the mutant, MT-I mRNA concentrations were normal. There was no difference between the MT-I mRNA in the brain of mutant and normal in the first 10 days of life, but after day 10 metallothionein mRNA levels were increased in the mutant. The concentration of copper was very low in the liver of the mutant, and on day 6 after birth the metallothionein mRNA was also reduced by about 50%. This reduction was not seen in copper-deficient 6-day-old pups, despite very low hepatic copper levels. This suggests that the lower hepatic MT-I mRNA in the day 6 brindled mouse was not simply due to the reduction in hepatic copper and also that hepatic copper is not regulating metallothionein gene expression the liver of neonatal mice. After day 12 hepatic MT-I mRNA levels were elevated in mutant and in copper deficient mice, both of which die at 14 to 16 days. These increases and the increase in brain MT-I mRNA in older mutant mice are likely to be caused by stress. Overall the results support the conclusions that the brindled mutation does not cause a constitutive activation of the metallothionein genes, and that the differences in metallothionein mRNA between mutant and normal are most probably secondary consequences of the mutation.     

冬小麦春化过程中低温诱导的与花芽分化相关的mRNA和蛋白质的合成

应用SDS电泳及高分辨双向电泳技术,分析了冬小麦经春化、脱春化及超期春化处理后茎类蛋白质组分的变化。发现52.5,38kD和16.2kD蛋白质与冬小麦开花诱导密切相关。mRNA体外翻译结果表明,春化作用中低温诱导与开花紧密相关的mRNA的出现有一定的顺序性。因此推测:春化诱导开花是低温导致某些特定基因表达的结果,而表达的调节主要发生在转录水平上。     

牛泌乳素mRNA的分离及鉴定

本文报道了从牛脑垂体提取总RNA,经寡聚脱氧胸苷纤维素亲合层析分离获得牛脑垂体Poly(A)~+RNA。牛泌乳素mRNA经含羟甲基汞琼脂糖凝胶电泳分析,估计其长度约为1200个核苷酸。根据牛泌乳素的部分氨基酸序列推断并合成寡聚核苷酸探针,经Northern印迹杂交及放射自显影分析,证实了该mRNA中含有牛泌乳素mRNA的序列。在兔网织红细胞体外翻译体系中,牛泌乳素mRNA促进了~35S-甲硫氨酸参入,翻译合成的初级翻译产物能与兔抗羊PRL抗血清发生特异性免疫沉淀反应,SDS聚丙烯酰胺凝胶电泳及放射自显影分析结果表明,牛泌乳素前体的分子量约25000。     

Phytochrome control of plastid mRNA in mustard (Sinapis alba L.)

The steady-state levels of plastid RNA sequences in dark-grown and light-grown mustard (Sinapis alba L.) seedlings have been compared. Total cellular RNAs were labeled in vitro with ³²P and hybridized to separated restriction fragments of plastid DNA. Cloned DNA fragments which encode the large subunit (LS) of ribulose-1,5-bisphosphate carboxylase [3-phospho-D-glycerate carboxylase (dimerizing), EC 4.1.1.39] and a 35,000 plastid polypeptide were used as probes to assess the levels of these two plastid mRNAs. The 1.22-kilobase-pair mRNA for the 35,000 polypeptide is almost undetectable in dark-grown seedlings, but is a major plastid mRNA in light-grown seedlings. The hybridization analysis of RNA from seedlings which were irradiated with red and far-red light indicates that the level of this mRNA, but not of LS mRNA, is controlled by phytochrome.Abbreviations LS large subunit - RuBP ribulose-1,5-bisphosphate - ptDNA plastid DNA     

Evolutionary analysis ofα andβ hemoglobin genes by reh theory under the assumption of the equiprobability of genetic events

Summary It is shown how REH theory in conjunction with mRNA or gene sequence data can be used to obtain estimates of the fixation intensity, the number of varions, and the total mutations fixed between homologous pairs of nucleic acids. These estimates are more accurate than those that can be derived from amino acid sequence data. The method is illustrated for and hemoglobin genes and these improved estimates are compared with those made from the amino acid sequences for which those genes code. Significant differences are found between the estimates made by these two methods. For the hemoglobin gene sequences examined here, the fixation intensity is some-what less than the protein data had suggested, and the number of rations is considerably greater. Depending on the gene sequences examined, between 62 and 83% of the codons appear able to fix mutations during the divergences considered. This reflects the constraints of natural selection on acceptable mutations. The total number of base replacements separating the genes for human, mouse, and rabbit hemoglobin varies from 61 to 105 depending on the pair examined. Rabbit and hemoglobin are separated by at least 290 fixed mutations. For such distantly related sequences estimates made from protein and mRNA data differ less, reflecting the higher quality of information from the many observed changes in primary structure. The effects of nonrandom gene structure on these evolutionary estimates and the fact that various genetic events are not equiprobable are discussed.     

Location of ribosome-binding sites in the nin5 region of bacteriophage lambda

Seven ribosome-binding sites on DNA have been located within the region defined by the nin5 deletion as well as several ribosome-binding sites on each side of the nin5 region. These were mapped by electron microscopy relative to the end points of the nin5 deletion and two Tn903 transposons, one inserted into gene Rz and another inserted near gene Q. These ribosomes binding sites within the nin5 region may correspond to polypeptide initiation sites for up to seven new dispensible lambda genes.