1,720,984 research outputs found
Analisi del meccanismo molecolare e del ruolo fisiologico dell'espressione differenziale del gene per il tRNA - Val (GAC) nella embriogenesi somatica di Daucus carota.
No full textAn efficient method for preparing high quality DNA from plant DNA libraries in lambda phage
No full textAn efficient method has been developed to improve preparation of phage particles by ammonium sulfate precipitation and to yield high quality DNA. The method, that has been used to screen plant DNA libraries constructed in vectors, is inexpensive, does not require purification of phage particles, and can be used from either plate stocks or liquid lysates. Up to 1100 mug DNA was produced from 5 ml lysate obtained from agar plates
Hyper-expression of small nucleolar RNAs (snoRNAs) in female inflorescences of hazelnut (Corylus avellana L.) supports rRNA aggregation in vitro
No full textUnder certain in vitro (salt and temperature) conditions rRNA aggregation occurs in female inflorescences but not in leaves or pollen RNA preparations from hazelnut (Corylus avellana L.), a species of economic interest. This paper describes experiments addressing an explanation of this phenomenon. The experiments demonstrate that: (i) trans-acting factors induce rRNA aggregate formation in female inflorescences RNA preparations; (ii) these factors support aggregation also of heterologous rRNA; (iii) aggregation is a function of temperature pre-treatment of rRNA and not of source 18S rRNA; (iv) the factors inducing rRNA aggregates are sensitive to RNase; (v) antisense small nucleolar RNAs (snoRNAs) participate in rRNA aggregate formation. snoRNAs are involved in pre-rRNA spacer cleavages, and are required for the two most common types of rRNA modifications: 2'-O-ribose methylation and pseudouridylation. Even though it is questionable whether rRNA aggregation really happens in female inflorescence in vivo, the phenomenon observed in vitro may reflect the abundance of snoRNAs in these reproductive structures. In fact the level of accumulation of three tested snoRNAs, R1, U14 and U3, is much higher in female inflorescence than in leaves or pollen of hazelnut. This finding opens the possibility of studying the role of snoRNAs in tissue development in plants
A tRNA gene mapping within the chloroplast rDNA "cluster" is differentially expressed during the development of Daucus carota.
No full textAttivazione di promotori interni dell'elemento trasponibile Mu1 di Mais durante lo sviluppo.
No full textA reilable and inexpensive procedure for isolation of both cytoplasmic and mitochondrial RNA from yeast.
No full textGenotypic identification of a Debaryomyces hansenii yeast strain isolated from tobacco leaves.
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Hypermutation in pathogenic bacteria: frequent phase variation in meningococci is a phenotypic trait of a specialized mutator biotype
No full textExpression of serogroup B meningococcal capsular polysaccharide undergoes frequent phase variation involving reversible frameshift mutations within a homopolymeric repeat in the siaD gene. A high rate of phase variation is the consequence of a biochemical defect in methyl-directed mismatch repair. The mutator phenotype is associated to the absence of DNA adenine methyltransferase (Dam) activity in all pathogenic isolates and in 50% of commensal strains. Analysis of the meningococcal dam gene region revealed that in all Dam- strains a gene encoding a putative restriction endonuclease (drg) that cleaves only the methylated DNA sequence 5'-GmeATC-3' replaced the dam gene. Insertional inactivation of the dam and/or drg genes indicated that high rates of phase variation and hypermutator phenotype are caused by absence of a functional dam gene
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