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Biomedical subjects

M Holdsworth

Publications and source records attributed to M Holdsworth.

5 recordsLinked to original sources
PubMed1997

The wheat transcriptional activator SPA: a seed-specific bZIP protein that recognizes the GCN4-like motif in the bifactorial endosperm box of prolamin genes.

The conserved bifactorial endosperm box found in the promoter of wheat storage protein genes comprises two different cis elements that are thought to be involved in regulating endosperm-specific gene expression. Endosperm nuclear extracts contain binding activities. One is called ESBF-I, which binds to the endosperm motif (EM), and the other is called ESBF-II, which binds to the GCN4-like motif(GLM). Here, we present a functional analysis of the endosperm box of a low-molecular-weight glutenin gene found on the 1D1 chromosome of hexaploid wheat (LMWG-1D1) in transgenic tobacco plants. Our analysis demonstrates the necessity of the EM and GLM for endosperm-specific gene expression and suggests the presence in tobacco of functional counterparts of wheat ESBF-I and ESBF-II. Furthermore, we describe the isolation and characterization of cDNA clones encoding SPA, a seed-specific basic leucine zipper protein from wheat that can activate transcription from the GLMs of the -326-bp LMWG-1D1 promoter in both maize and tobacco leaf protoplasts. This activation is also partially dependent on the presence of functional EMs, suggesting interactions between SPA with ESBF-I-like activities.

Amino Acid Sequence↗
PubMed1994

Separate cis sequences and trans factors direct metabolic and developmental regulation of a potato tuber storage protein gene.

The expression of genes encoding patatin, a major tuber protein, is highly tissue-specific but is also modulated by exogenous sucrose. The patterns of transcription observed in potato plants could be due to mechanisms conferring tuber-specificity or they could reflect the concentrations of sucrose found in different tissues. To distinguish between these possibilities, a detailed examination was made of the function of a region of the promoter previously implicated in conferring tissue-specific and sucrose-inducible expression. Internal deletions of this region revealed three separate functional domains regulating expression. The B repeat region acted as a positive activator of transcription in the tuber and was also responsible for a degree of sucrose-inducibility. The distal region of the A repeat repressed transcription in leaf and tuber tissue, while the proximal region of the A repeat was able to confer sucrose-responsiveness. Each of these regions specifically bound nuclear proteins which may be putative transcription factors involved in conferring these responses. The region found to confer sucrose-inducible expression was conserved among some other genes that are also regulated by exogenous sucrose.

Base Sequence↗
PubMed1993

Transcriptional control of plant storage protein genes.

The accumulation of plant storage proteins is controlled primarily by the transcriptional activation of their genes. Two classes of storage proteins, the zygotic or seed-specific, and the somatic, such as tuber proteins, have been studied. Gene expression analysis in transgenic plants has defined small regions of the promoters of such genes that are able to confer the appropriate patterns of expression. Protein-DNA interactions, both in vivo and in vitro, have revealed proteins that bind to regions implicated in expression, and these may be transcription factors. Promoter deletion analysis has determined the role of some of these DNA-binding proteins, such as in determining tissue-specificity or levels of expression. A common theme linking the expression of both classes of storage proteins is the involvement of metabolite levels in directly controlling gene expression.

Base Sequence↗
PubMed1992

Gender-linked differences in everyday memory performance.

Recent research has demonstrated that people hold beliefs about how well others perform everyday memory tasks according to another's sex. For example, meta-memory ratings indicate that other men and other women are believed to differ in their success at performing certain memory tasks (Crawford, Herrmann, Holdsworth, Randall & Robbins, 1989). In the present study, two experiments investigated whether gender stereotypes concerning everyday memory have any validity. Experiment 1 presented female and male subjects with two tasks that the aforementioned meta-memory ratings had shown are implicitly gender marked: learning a shopping list (a sterotypically feminine task) and learning directions to go to a particular place (a stereotypically masculine task). The results were consistent with the gender stereotypes, i.e. women recalled more of the shopping list than men whereas men recalled more of the directions than women. The second experiment investigated whether memory performance would be influenced by mere changes in the label of materials in memory tasks to be biased toward male or female gender background: labelling a shopping list as pertaining to 'groceries' or to 'hardware store'; and a set of directions to 'make a shirt' or to 'make a workbench'. The results also indicated that memory performance varied in ways consistent with gender stereotypes.

Adolescent↗