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PubMed1992

Inhibition of the ADP-glucose pyrophosphorylase in transgenic potatoes leads to sugar-storing tubers and influences tuber formation and expression of tuber storage protein genes.

Transgenic potato plants were created in which the expression of ADP-glucose pyrophosphorylase (AGPase) was inhibited by introducing a chimeric gene containing the coding region of one of the subunits of the AGPase linked in an antisense orientation to the CaMV 35S promoter. Partial inhibition of the AGPase enzyme was achieved in leaves and almost complete inhibition in tubers. This resulted in the abolition of starch formation in tubers, thus proving that AGPase has a unique role in starch biosynthesis in plants. Instead up to 30% of the dry weight of the transgenic potato tubers was represented by sucrose and up to 8% by glucose. The process of tuber formation also changed, resulting in significantly more tubers both per plant and per stolon. The accumulation of soluble sugars in tubers of antisense plants resulted in a significant increase of the total tuber fresh weight, but a decrease in dry weight of tubers. There was no significant change in the RNA levels of several other starch biosynthetic enzymes, but there was a great increase in the RNA level of the major sucrose synthesizing enzyme sucrose phosphate synthase. In addition, the inhibition of starch biosynthesis was accompanied by a massive reduction in the expression of the major storage protein species of potato tubers, supporting the idea that the expression of storage protein genes is in some way connected to carbohydrate formation in sink storage tissues.

Blotting, Northern↗

PubMed1987

The two classes of genes for the major potato tuber protein, patatin, are differentially expressed in tubers and roots.

The major potato tuber protein, patatin, is a family of 40kd glycoproteins that constitutes forty per cent of the soluble protein in tubers but is generally undetectable in other tissues. Fused rocket immunoelectro-phoresis was used to detect in roots patatin that is immunologically different from tuber patatin. Western blots of SDS-polyacrylamide gels show root patatin to have a different molecular weight distribution than tuber patatin isoforms, but immunoprecipitation of in vitro translation products shows the patatin precursors to be of similar molecular weight in both tissues. This suggests that post-translational processing may differ in tubers and roots. Northern blots show that tuber and root patatin mRNAs are of similar size, but tuber transcripts are about 100-fold more abundant. 5' S1 nuclease and primer extension mapping suggests the class of patatin transcripts expressed in roots (class II transcripts) to be a subset of patatin transcripts expressed in tubers (classes I and II). Class II patatin mRNAs differ from class I transcripts by the presence of a 22 nucleotide insertion just upstream of the initiation codon. These data demonstrate that expression of the patatin multigene family is differentially regulated in tubers and roots.

Base Sequence↗

PubMed1992

Linkage investigation of three putative tuberous sclerosis determining loci on chromosomes 9q, 11q, and 12q. The Tuberous Sclerosis Collaborative Group.

Previous linkage studies in tuberous sclerosis have implicated three disease determining loci at 9q, 11q, and 12q. We have collated phenotypic and genotypic data on 1622 members of 128 families with tuberous sclerosis in order to evaluate simultaneously the evidence for these putative loci. Affection status in the family members has been reassessed using uniform diagnostic criteria and genotypic data extensively checked before analysis under alternative models of locus heterogeneity. One tuberous sclerosis determining locus, accounting for approximately 50% of the families studied, has been found to map in the region of D9S10 on 9q34 but no evidence has been found to support the existence of major loci on 11q or 12q. A locus, or loci, elsewhere in the genome is likely to account for tuberous sclerosis in most non-chromosome 9 linked families.

Chromosome Mapping↗

PubMed1987

Use of an in vitro tuberization system to study tuber protein gene expression.

Nodal cuttings from micropropagated potato plantlets give rise to microtubers when placed on Murashige and Skoog medium containing 6% sucrose and 2.5 mg/liter kinetin and incubated in the dark at 19 degrees C. Microtubers produced from the cultivar Superior were shown to contain the same characteristic group of proteins as field-grown tubers. As with field-grown tubers, the 40,000-dalton major tuber glycoprotein, patatin, accumulated to high levels in microtubers, reaching 3.7 +/- 0.2 mg/g fresh weight after 90 d. Also in agreement with field-grown plants, stems and leaves of micropropagated plantlets did not contain detectable levels of patatin, but small amounts of an electrophoretically distinct form accumulated transiently in roots. Patatin mRNA is readily detectable in developing microtubers 15 d after transfer of the cuttings to inductive medium. Patatin mRNA was also present in roots, but as with field-grown plants, was 50- to 100-fold less abundant and could be distinguished from that in tubers by primer extension. Microtuber development and patatin accumulation were inhibited by gibberellic acid.

Gene Expression Regulation↗

PubMed1987

Purification and properties of lectin from potato tubers and leaves; interaction with acid phosphatase from potato tuber.

The haemagglutination activity of lectin, (STA) was determined during vegetation of potatoes (Solanum tuberosum var. Uran). Traces of haemagglutination activity were found in young stalks and first leaves. In the next leaves the maximal activity appeared after 6-8 weeks of vegetation and, simultaneously with the decrease in leaves it appeared in young tubers (at the time of their differentiation from stolons), reaching the maximum in the 18th week of vegetation. Lectins from potato tubers and leaves were extracted with acetate buffer, pH 3.6, salted out with ammonium sulphate, and purified alternatively by affinity chromatography on GlcNAc-Spheron or by adsorption on trypsinated and glutaraldehyde-fixed rabbit erythrocytes. Chromatography on Sephadex G-200 was used for preparative separation of isomeric forms. In the tubers four isolectins were found, differeing in molecular mass, pI values, content of sugars and haemagglutination activity. Two of these forms were isolated in homogeneous form: a heavy dimeric form, Mr 130,000-142,000 containing 59.6% of sugars (including 28.8% arabinose, 6.9% galactose, 16.5% glucose, 1.6% xylose and 3.1% mannose), and a light monomeric form. of Mr 21,000-22,000, containing 20% of neutral sugars (2.5% of pentoses and 17.5% of hexoses). From leaves, a single heavy dimeric lectin of Mr 136,000, containing 14.3% of neutral sugars was isolated. The effect of tuber isolectin on the activity, pH optima and heat-stability of the potato acid phosphatase has been described.

Acid Phosphatase↗

PubMed1990

Neonatal tuberous sclerosis: magnetic resonance appearance of subependymal tubers.

A case of tuberous sclerosis in a neonate, with cerebral and cardiac hamartomas evaluated by MR imaging, is presented. Intracranial subependymal tubers in this neonate exhibit increased signal intensity on short TR images. This differs from the signal characteristics of subependymal tubers in older patients.

Brain↗

PubMed1992

Amino acid sequence of the N-terminal domain of yam (Dioscorea japonica) aerial tuber acidic chitinase. Evidence for the presence of a wheat germ agglutinin domain in matured acidic chitinase from unstressed tuber.

The amino acid sequence of the N-terminal domain of acidic chitinase from unstressed aerial tuber was determined and proved the presence of an N-terminal domain in acidic chitinase. The amino acid sequence was determined on a pyroglutamylaminopeptidase-treated N-terminal fragment of V8 protease and on chymotryptic peptides of this fragment. The sequence determined revealed 8 residues deletion and 2 residues insertion as compared with the N-terminal domain of tobacco basic chitinase. The N-terminal domain determined showed a homology of 40% and 52% with the N-terminal domain of tobacco basic chitinase and wheat germ agglutinin, respectively.

Amino Acid Sequence↗

PubMed1990

Detection of potato spindle tuber viroid (PSTV) in dormant potato tubers by concatameric cDNA probe.

The 32P-labelled concatameric insert cut out from a plasmid pSPAv6.2(+), containing 6.2 copies of a full-length PSTV, was used to detect PSTV in dormant potato tubers by dot-blot hybridisation assay. The concatameric insert probe was 4 times more sensitive than the monomeric one. This allowed the detection of 0.5 pg of viroid RNA. The sensitivity makes th eoligomeric cDNA probe a useful alternative to cDNA probes.

DNA Probes↗

PubMed1990

[Pharmacological study on Aconiti Tuber. I. Effect of water extract from Aconiti Tuber on adjuvant-induced arthritis].

Anti-inflammatory activity of a hot water extract (A-ext) of Aconiti Tuber (Aconitum calmicaeli DEBX.) has been studied by using various experimental models. The successive administration of A-ext from the day of injection of adjuvant agent or 5 d after the injection it significantly inhibited the adjuvant-induced arthritis developed in the primary and secondary lesions in rats. However, when A-ext was administered from 11 d after the injection of adjuvant, the arthritic paw edema was not reduced. A-ext did not inhibit an acetic acid-induced increase in vascular permeability in mice and carrageenin-induced paw edema in rats. A-ext inhibited cotton pellet-induced granuloma in rats, but did not suppress the weight of thymus and adrenal gland. In vitro experiment, A-ext contracted the isolated ileum of guinea pig, but the contractive activity was reduced by pretreatment of anti-histamine agent, diphenhydramine, but not by pretreatment of papaverine or atropine. A-ext did not release histamine from peritoneal mast cell. These results suggest that A-ext prevents the adjuvant-induced arthritis and has a histamine-like effect.

Animals↗

PubMed1992