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A Viotti

Publications and source records attributed to A Viotti.

7 recordsLinked to original sources
PubMed1992

Functional analysis of the regulatory region of a zein gene in transiently transformed protoplasts.

The transcription of zein genes in maize is tissue-specific and developmentally regulated. The 5' regulatory region of many zein genes contains two promoters, P1 and P2, lying approximately 1000 bases apart. The promoter/enhancer activity of various fragments of the two promoter regions of the zein gene E19 have been analysed by means of transient expression experiments. The results indicate that the various regions differentially affect the expression of the GUS reporter gene activity in protoplasts from tobacco leaves, maize immature endosperms and in vitro endosperm cell cultures. In tobacco protoplasts only the proximal promoter region, P2, activates GUS expression, while in endosperm culture cells only the distant promoter, P1, gives significant activity. The P1 region, both in direct and opposite orientation, stimulates a low level of GUS expression in protoplasts from immature endosperms.

Base Sequence↗
PubMed1991

Genetic and molecular analysis of Sn, a light-inducible, tissue specific regulatory gene in maize.

The Sn locus of maize is functionally similar to the R and B loci, in that Sn differentially controls the tissue-specific deposition of anthocyanin pigments in certain seedling and plant cells. We show that Sn shows molecular similarity to the R gene and have used R DNA probes to characterize several Sn alleles. Northern analysis demonstrates that all Sn alleles encode a 2.5 kb transcript, which is expressed in a tissue-specific fashion consistent with the distribution of anthocyanins. Expression of the Sn gene is light-regulated. However, the Sn: bol3 allele allows Sn mRNA transcription to occur in the dark, leading to pigmentation in dark-grown seedlings and cob integuments. We report the isolation of genomic and cDNA clones of the light-independent Sn: bol3 allele. Using Sn cDNA as a probe, the spatial and temporal expression of Sn has been examined. The cell-specific localization of Sn mRNA has been confirmed by in situ hybridization using labelled antisense RNA probes. According to its proposed regulatory role, expression of Sn precedes and, in turn, causes a coordinate and tissue-specific accumulation of mRNA of structural genes for pigment synthesis and deposition, such as A1 and C2. The functional and structural relationship between R, B, Lc and Sn is discussed in terms of an evolutionary derivation from a single ancestral gene which gave rise this diverse gene family by successive duplication events.

Acyltransferases↗
PubMed1990

The maize zein gene zE19 contains two distinct promoters which are independently activated in endosperm and anthers of transgenic Petunia plants.

The activity, tissue specificity and temporal expression of the tandem promoter region preceding a maize zein gene (zE19, encoding a 19 kDa zein protein) were tested in transgenic Petunia plants. To simplify the analysis, the tandem promoter as well as each of the two separate promoter regions were fused to the beta-glucuronidase (GUS) reporter gene. All of the three constructs directed the synthesis of GUS in the endosperm of transformed seeds indicating that both separate promoters are independently activated and show the same tissue and cell type specificity observed for zein genes in maize. The kinetics of accumulation and the localization of GUS activity are not coordinated with those of Petunia endogenous seed storage proteins during the development of transformed seeds. Unexpectedly, we detected high levels of GUS activity in anthers of transformed Petunia plants for all three constructs. This appears to reflect the expression pattern of zein genes in maize, since we detect zein transcripts in anthers. Finally, we discuss the possible origin and function of the tandem promoter arrangement on the basis of these data.

Base Sequence↗
PubMed1979

Genes and mRNAs coding for zein polypeptides in Zea mays.

Zein messenger RNAs from maize endosperm were purified by successive oligo(dT)-cellulose chromatography and sucrose gradient centrifugation. Polyacrylamide gel electrophoresis under denaturing conditions revealed the presence of two size classes of zein messenger RNAs of Mr 3.5 x 10(5) and 4.10 x 10(5). The mRNA was shown to synthesize the major zein polypeptides, to have a base composition characteristic of a poly(A)-containing RNA and to be transcribed by reverse transcriptase into complementary DNA. The r0t1/2 of the hybridization curve of cDNA hybridized to an excess of mRNA was shown to be 7 x 10(-2) M . s indicating that about 15 non-cross-hybridizing sequences are present in the zein mRNA preparations. The kinetics of cDNA annealing with an excess of maize DNA from 2 n cells suggest a ten-times reiteration of each mRNA sequence. This result is confirmed from saturation experiments, where in cDNA excess to DNA, the number of zein genes per haploid maize genome was estimated as about 120 copies. Similar experiments carried out on DNA from normal and mutant endosperms (3n cells) indicate the absence of large amplifications or deletions of zein genes in the tissue devoted to zein synthesis.

DNA↗
PubMed1978

Adaptation of the tRNA population of maize endosperm for zein synthesis.

Maize endosperm, 30 days after pollination is actively synthesizing zein, a storage protein containing high amounts of glutamine. leucine and alanine. Endosperm tRNAs have a higher accepting activity than embryo tRNAs for these three amino acids, but not for some other (control) amino acids. This increase in accepting activity is accompanied by a change in the distribution of the isoaccepting tRNA species corresponding to these three amino acids, but not of the isoacceptors corresponding to some other (control) amino acids. These results are in favor of the theory of functional adaptation of tRNA population.

Alanine↗