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61.
Uniparental Mitochondrial Transmission in the Cultivated Button Mushroom, Agaricus bisporus 总被引:2,自引:1,他引:1
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A uniparental mitochondrial (mt) transmission pattern has been previously observed in laboratory matings of the cultivated mushroom Agaricus bisporus on petri dishes. In this study, four sets of specific matings were further examined by taking mycelial plugs from the confluent zone of mated homokaryons and inoculating these plugs into rye grain for laboratory fruiting and for fruiting under industrial conditions. Examination of the mt genotype of each individual fruit body for mt-specific restriction fragment length polymorphisms further confirmed that the mt genome was inherited uniparentally. The vegetative radial growth and the fruiting activity of two pairs of intraspecific heterokaryons, each pair carrying the same combination of nuclear genomes but different mt genotypes, were compared. Our results suggested that the mt genotype did not appreciably affect radial growth or fruiting activity. The failure to recover both heterokaryons, each carrying either parental mt genotype in any given cross, therefore clearly indicated that in matings of A. bisporus, the mt genome from one of the parental homokaryons is either selectively excluded in the newly formed heterokaryon or selectively eliminated in the immediate heterokaryotic mitotic progeny of the newly formed heterokaryon. 相似文献
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Jin Feng Kunitoshi Yamanaka Hironori Niki Teru Ogura Sota Hiraga 《Molecular & general genetics : MGG》1994,243(2):136-147
The nucleotide sequence was determined of the region upstream of the mukB gene of Escherichia coli. Two new genes were found, designated kicA and kicB (killing of cell); the gene order is kicB-kicA-mukB. Promoter activities were detected in the regions immediately upstream of kicB and kicA, but not in front of mukB. Gene disruption experiments revealed that the kicA disruptant was nonviable, but the kicB-disrupted mutant and the mutant lacking both the kicB and kicA genes were able to grow. When kicA disruptant cells bearing a temperature-sensitive replication plasmid carrying the kicA
+ gene were grown at 30° C and then transferred to 42° C, the mutant cells gradually lost colony-forming ability, even in the presence of a mukB
+ plasmid. Rates of protein synthesis, but not of RNA or DNA synthesis, fell dramatically during incubation at 42° C. These results suggested that the kicB gene encodes a killing factor and the kicA gene codes for a protein that suppresses the killing function of the kicB gene product. It was also demonstrated that KicA and KicB can function as a post-segregational killing system, when the genes are transferred from the E. coli chromosome onto a plasmid. 相似文献
63.
向日葵幼苗环旋运动的三维轨迹 总被引:1,自引:0,他引:1
采用光学显微镜标尺和垂线原理制作的三维空间点测定仪,对向日葵(Helianthus annuusL.)幼苗的环旋运动进行了连续测量。结果表明:向日葵环旋运动的轨迹有椭圆型、摆动型和不规则型;同一植株在不同生长阶段所表现的环旋运动轨迹不一定相同,同一株龄的不同个体也不一定具有相同的运动轨迹;运动的方向有左旋和右旋,圆周运动光源可以显著地改变运动方向;从三维角度看,在整个下胚轴生长阶段,环旋运动的振幅存在一个由小变大再由大变小的变化规律 相似文献
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Almost every cell in the Drosophila pupal wing forms a single, distally pointing cuticular hair. The function of the frizzled (fz) gene is essential for the elaboration of the normal wing hair pattern. In the absence of fz function hairs develop, but they display an abnormal polarity. We have examined the developmental expression of the fi gene at the RNA level via in situ hybridization and at the protein level via Western blotting. We have found that fz is expressed in all regions of the epidermis before, during, and after the fz cold sensitive period. We have also found that fz function is not required for normal fi expression. We have further found that mutations in several other tissue polarity genes do not noticeably alter the expression or the modification state of the Fz protein. © 1994 Wiley-Liss, Inc. 相似文献
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The dependence of blastocyst development on the extracellular Na+/K+ ratio was investigated in an in vitro system. Hatching and outgrowth of mouse blastocysts was enhanced at Na+/K+ ratios between 3 and 10 compared to the ratio of about 25 typical for most culture media and serum. At a Na+/K+ ratio of 2, blastocyst hatching and outgrowth were inhibited. The requirement of blastocyst development for relatively high extracellular K+ concentrations agrees with the fact that K+ concentrations in oviduct and uterine secretions are higher than in serum. The findings can also be relevant in optimizing in vitro culturing techniques for blastocysts. 相似文献