Biomedical subjects

Andrew Poole

Publications and source records attributed to Andrew Poole.

3 recordsLinked to original sources

PubMed2006

A mutation affecting ASCORBATE PEROXIDASE 2 gene expression reveals a link between responses to high light and drought tolerance.

Molecular analyses of plants have revealed a number of genes whose expression changes in response to high light (HL), including the H2O2 scavenger, ASCORBATE PEROXIDASE 2 (APX2). We carried out a screen in Arabidopsis thaliana for lesions that alter HL-induced expression of APX2 to identify components in abiotic stress signalling pathways. High light was used as it can be instantaneously applied or removed and accurately measured. We identified a number of alx mutations causing altered APX2 expression. Here we describe the gain-of-function mutant, alx8, which has constitutively higher APX2 expression and higher levels of foliar abscisic acid (ABA) than wild type. In fact, exogenous ABA increased APX2 expression and the APX2 promoter contains ABA response elements. Furthermore, we have shown that HL stress increases ABA in wild-type plants, implicating ABA in the regulation of HL-inducible genes. The alx8 mutant is drought tolerant, exhibits improved water-use efficiency and a number of drought-tolerance genes are upregulated. Additionally, alx8 demonstrates the complexity of ABA-dependent and ABA-independent transcriptional networks as some components in both pathways are upregulated in alx8. This study provides evidence for common steps in drought and HL stress response pathways.

Abscisic Acid↗

PubMed2005

Antisense suppression of a (+)-delta-cadinene synthase gene in cotton prevents the induction of this defense response gene during bacterial blight infection but not its constitutive expression.

In cotton (Gossypium hirsutum) the enzyme (+)-delta-cadinene synthase (CDNS) catalyzes the first committed step in the biosynthesis of cadinane-type sesquiterpenes, such as gossypol, that provide constitutive and inducible protection against pests and diseases. A cotton cDNA clone encoding CDNS (cdn1-C4) was isolated from developing embryos and functionally characterized. Southern analysis showed that CDNS genes belong to a large multigene family, of which five genomic clones were studied, including three pseudogenes and one gene that may represent another subfamily of CDNS. CDNS expression was shown to be induced in cotton infected with either the bacterial blight or verticillium wilt pathogens. Constructs for the constitutive or seed-specific antisense suppression of cdn1-C4 were introduced into cotton by Agrobacterium-mediated transformation. Gossypol levels were not reduced in the seeds of transformants with either construct, nor was the induction of CDNS expression affected in stems of the constitutive antisense plants infected with Verticillium dahliae Kleb. However, the induction of CDNS mRNA and protein in response to bacterial blight infection of cotyledons was completely blocked in the constitutive antisense plants. These results suggest that cdn1-C4 may be involved specifically in the bacterial blight response and that the CDNS multigene family comprises a complex set of genes differing in their temporal and spatial regulation and responsible for different branches of the cotton sesquiterpene pathway.

Base Sequence↗

PubMedDate not supplied

Taurodontism and learning disabilities in patients with Klinefelter syndrome.

PURPOSE: The purpose of this descriptive clinical study was to determine the prevalence rates of taurodontism and learning disabilities in a sample of patients with Klinefelter syndrome. METHODS: Questionnaires and dental radiographs of Klinefelter syndrome patients were obtained and analyzed using previously published methods. Prevalence rates were determined for taurodontism and learning disabilities in the sample population and compared to the general population. Statistical analyses included a Fisher's exact 2-sided test to compare the prevalence rates to that found in the general population and subsequent determination of the positive predictive value. RESULTS: Taurodontism was found in 75% of the 24 participants. Eighty-three percent of the participants reported having a learning disability. These rates are significantly higher than the general population, as reported in the literature. CONCLUSIONS: The positive predictive value for Klinefelter syndrome, given a male patient with taurodontism and a learning disability, is 84%. In this case, the dentist should recommend karyotyping to the patient, parent, or physician. This demonstrates how important it is for dentists to understand and assist physicians in the diagnosis of genetic disorders.

Adolescent↗