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Wilt-induced ABA biosynthesis, gene expression and down-regulation of rbcS mRNA levels in Arabidopsis thaliana (1994)

Williams, J. ; Bulman, M. P. ; Neill, S. J.

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 91 (1994), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The kinetics of wilt-induced abscisic acid (ABA) biosynthesis were investigated in shoots of Arabidopsis thaliana (L.) Heynh Landsberg erecta. ABA concentrations were measured using a radioimmunoassay (RIA) based on the monoclonal antibody MAC 252, and the RIA validated by comparison with combined gas chromatography-mass spectrometry using a [2H3] labelled internal standard. The basal ABA content of Arabidopsis shoots was ca 10 ng g−1 fresh weight; the concentrations had increased ca 4-fold within 30 min of the initiation of wilting, increased ca 8-fold after 4 h and 11-fold after 8 h. This stress-induced ABA production was dependent on de novo gene expression; pre-treatment of leaves and shoots with the metabolic inhibitors cordycepin and cycloheximide reduced the rate of subsequent stress-induced ABA biosynthesis from 12.5 ng g−1 h−1 to 1 ng g−1 h−1 and 0 ng g−1 h−1, respectively. In vitro translation of mRNA isolated from shoots subjected to wilting or ABA treatment followed by one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis revealed only minor changes. The effects of wilting and ABA on the content of total ribulose 1,5-bisphosphate carboxylase/oxygenase small sub-unit (rbcS) mRNA were also determined. Both wilting and exogenous ABA resulted in a substantial reduction in the amount of rbcS mRNA, an effect readily reversed by rehydration of wilted shoots. However, the effects of wilting were not mediated solely by newly-synthesised endogenous ABA, as wilting also reduced rbcS mRNA levels in the ABA-deficient aba-1 mutant, which did not produce ABA in response to loss of turgor. The amount of rbcS mRNA was higher in aba-1 shoots, suggesting that cellular rbcS mRNA levels are normally down-regulated by ABA. Cold treatment induced ABA production in wild type shoots only, but resulted in an increased rbcS mRNA content of both wild type and aba-1 shoots.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb00416.x

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A missense mutation in the hepatocyte nuclear factor 4 alpha gene in a UK pedigree with maturity-onset diabetes of the young (1997)

Bulman, M. P. ; Dronsfield, M. J. ; Frayling, T. ; [et al.]

Springer

Diabetologia 40 (1997), S. 859-862

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ISSN: 1432-0428

Keywords: Keywords MODY ; MODY1 ; HNF-4α ; mutation analysis ; sequencing

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Maturity-onset diabetes of the young (MODY) is a monogenic subgroup of non-insulin dependent diabetes mellitus (NIDDM) characterised by an early age of onset (〈 25 years) and an autosomal dominant mode of inheritance. MODY is genetically heterogeneous with three different genes identified to date; hepatocyte nuclear factor 4 alpha (HNF-4α) [MODY1], glucokinase [MODY2] and hepatocyte nuclear factor 1 alpha (HNF-1α) [MODY3]. A nonsense mutation in the HNF-4α gene has recently been shown to cause MODY in a single large North American pedigree (RW). We screened a large UK Caucasian MODY family which showed weak evidence of linkage to the MODY1 locus on chromosome 20q (lod score for ADA 0.68 at θ = 0) for mutations in the coding region of the HNF-4α gene by direct sequencing. A missense mutation resulting in the substitution of glutamine for glutamic acid was identified in exon 7 (E276Q). The mutation was present in all of the diabetic members of the pedigree plus two unaffected subjects and was not detected in 75 normal control subjects or 95 UK Caucasian subjects with late-onset NIDDM. This is the first missense mutation to be described in the HNF-4α gene. [Diabetologia (1997) 40: 859–862]