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Query: UNIPROT:P06889 (Mol)
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Dormant seeds do not germinate when imbibed in water even when conditions are favorable for germination. These hydrated seeds remain viable, but growth-arrested for weeks due to unknown restrictions within the embryo. As a model system for the study of the molecular processes occurring in dormant seeds, we have chosen to examine gene expression in Bromus secalinas, a grass species that produces seeds with high levels of embryonic dormancy. Using differential screening for mRNAs present in hydrated dormant embryos, we have identified a cDNA clone, pBS128, that encodes a mRNA transcript found in the embryos of hydrated seeds of B. secalinus as well as in embryos from mature dry seeds. Striking differences in pBS128 transcript levels appear upon hydration of dormant and nondormant seeds. Upon imbibition pBS128 transcript levels increase over four-fold in dormant seeds, but rapidly decline and disappear in nondormant seeds, which subsequently germinate. The pBS128 transcript appears to be embryo-specific since the transcript is not detectable in either non-stressed or dehydrated seedling tissue. Application of 50 microM ABA to nondormant seeds arrests germination and enhances pBS128 transcript levels. The nucleotide sequence of the nearly full-length pBS128 cDNA shows no homology to other reported genes, and the putative protein sequence does not exhibit the hydrophilic characteristics of the ABA-responsive LEA (late embryogenesis abundant) proteins.
Plant Mol Biol 1992 Jun
PMID:Cloning and expression of an embryo-specific mRNA up-regulated in hydrated dormant seeds. 137 65

The sequence of an oleosin gene from Brassica napus has been determined. This gene contains a single intron of 437 bp and encodes a polypeptide of 195 amino acids. The oleosin gene product has an estimated molecular mass of 21.5 kDa and consists of a highly hydrophobic central domain flanked by relatively polar N- and C-terminal domains. The central domain is highly conserved between all oleosins sequenced to date and contains a run of periodically spaced leucine residues similar to that of a leucine-zipper motif. The gene has been shown to be expressed specifically in the embryo, maximally between 9 and 11 weeks after flowering, i.e. during the seed desiccation stage. Two transcriptional start sites have been mapped to -70 and -21 of the ATG and a putative ABA-responsive element and three repeated motifs have been identified in the promoter. These short promoter sequences could correspond to regulatory elements responsible for embryo-specific gene expression. Up to six genes exist in the oleosin gene family.
Plant Mol Biol 1992 Jun
PMID:Cloning and characterisation of an oleosin gene from Brassica napus. 137 66

A Nicotiana tabacum gene encoding the basic PR-like protein osmotin was isolated and characterized. The gene is derived from the N. sylvestris parent of N. tabacum. In cell suspension cultures of tobacco, the osmotin gene was shown to be transcriptionally activated by treatment with ABA. Transcriptional activation of the osmotin promoter was further investigated in transformed plants carrying copies of a fusion of the cloned promoter to the beta-glucuronidase reporter gene. In these plants, the osmotin promoter is transcriptionally activated by the hormones ABA and ethylene. The sensitivity of the osmotin promoter to ABA applied exogenously decreased with age in both roots and shoots of young seedlings. NaCl shock also activated the promoter in plant tissues. The osmotin promoter is much more active in root tissues than in shoot tissues.
Plant Mol Biol 1992 Jul
PMID:Analysis of structure and transcriptional activation of an osmotin gene. 138 35

We have isolated a rab-related (responsive to ABA) gene, rab18 from Arabidopsis thaliana. The gene encodes a hydrophilic, glycine-rich protein (18.5 kDa), which contains the conserved serine- and lysine-rich domains characteristic of similar RAB proteins in other plant species. The rab18 mRNA accumulates in plants exposed to low temperature, water stress or exogenous ABA but not in plants subjected to heat shock. This stress-related accumulation of the rab18 mRNA is markedly decreased in the ABA-synthesis mutant aba-1, the ABA-response mutant abi-1 or in wild-type plants treated with the carotenoid synthesis inhibitor, fluridone. Exogenous ABA treatment can induce the rab18 mRNA in the aba-1 mutant but not in the abi-1 mutant. These results provide direct genetic evidence for the ABA-dependent regulation of the rab18 gene in A. thaliana.
Plant Mol Biol 1992 Dec
PMID:The expression of a rab-related gene, rab18, is induced by abscisic acid during the cold acclimation process of Arabidopsis thaliana (L.) Heynh. 844 52

A full-length tomato cDNA clone, TSW12, which is developmentally and environmentally regulated, has been isolated and characterized. TSW12 mRNA is accumulated during tomato seed germination and its level increases after NaCl treatment or heat shock. In mature plants, TSW12 mRNA is only detected upon treatment with NaCl, mannitol or ABA and its expression mainly occurs in stems. The nucleotide sequence of TSW12 includes an open reading frame coding for a basic protein of 114 amino acids; the first 23 amino acids exhibit the sequence characteristic of a signal peptide. The high similarity between the TSW12-deduced amino acid sequence and reported lipid transfer proteins suggests that TSW12 encodes a lipid transfer protein.
Plant Mol Biol 1992 Feb
PMID:A probable lipid transfer protein gene is induced by NaCl in stems of tomato plants. 155 48

We report the isolation of the second member, kin2, of a family of two cold-inducible genes of Arabidopsis thaliana. The proteins corresponding to the two genes have similarities to the small antifreeze proteins from Winter flounder. Kin1 and kin2 are organized in a close tandem array in the genome of A. thaliana. Both have three exons separated by introns with approximately the same length and location. The coding regions are highly conserved while the introns and especially the 3' flanking sequences of the mRNAs have diverged. The kin1 and kin2 genes are coordinately regulated in the cold. Unlike kin1, the kin2 mRNA has a detectable basal level, and accumulates to a higher level during acclimation. Both mRNAs are induced by 10 microM ABA but only kin2 responds strongly to drought and salinity stresses.
Plant Mol Biol 1992 Jul
PMID:Structure and expression of kin2, one of two cold- and ABA-induced genes of Arabidopsis thaliana. 162 80

The T cell response to L-tyrosine-azobenzenearsonate (ABA-tyr) has been studied using T cell lines and clones derived from three different mouse strains, B10.BR, B10.A (5R) and C57B1/6. In all cases, the arsonate group in conjunction with the amino group of tyrosine formed the functional T cell epitope. Molecules without any one or both of these groups are non-stimulatory. The hydrophobic moiety consisting of the azo-linked benzene rings forms the agretope of the molecule, as is evident from competitive inhibition of T cell stimulation by non-stimulatory analogues lacking the epitope. Substitutions on the benzene ring at ortho or meta positions resulted in decreases in ability to compete, indicating the likelihood of steric inhibition of binding of the agretope with the Ia molecule. This pattern was observed for clones and lines restricted by IAk, IAb and IEb/k MHC class II molecules. Peptides from lambda repressor protein, P84-98 and P73-88, showed haplotype specificity in their ability to inhibit ABA-tyr-induced proliferation of T cell clones, BRTC-4 and B6TC, respectively. The binding constants of ABA-tyr analogues were considered to be comparable to those of lambda repressor peptides because equimolar concentrations resulted in similar levels of competition. A cluster of aromatic amino acids on the floor of most MHC class II molecule binding sites might provide strong hydrophobic interaction with azo-linked benzene rings of ABA-tyr, thus accounting for its immunogenicity in all strains of mice studied.
Mol Immunol 1990 Jan
PMID:The presentation of L-tyrosine-azobenzenearsonate by different mouse Ia molecules uses a common agretope. 169 Mar 51

The major allergen from the body fluid of adult Ascaris suum (ABF) has been identified and purified to homogeneity using gel permeation high-performance liquid chromatography (HPLC). The purity of the Ascaris body fluid allergen (ABA-1) was confirmed by HPLC and SDS-PAGE. ABA-1 appears to be a 25-kDa dimer in its native form, which runs as a 10-kDa monomer on SDS-PAGE under reducing conditions. The allergenicity of the HPLC-purified protein was confirmed using isolated in vivo-sensitised mast cells from infected rats in an in vitro histamine release assay. ABA-1 is responsible for less than 80% of the allergenicity of ABF in this sensitive and specific system. Amino acid composition analysis and N-terminal amino acid sequencing were performed on ABA-1. Comparisons are made between ABA-1 and some of the heterogeneous Ascaris allergen preparations previously published. It is suggested that Asc-1 and allergen A both contain ABA-1 in large quantities and that discrepancies in the literature result from contaminating proteins in these preparations and technical differences in characterization of the predominant molecules present in the preparations. Compositional data suggests that the ABA-1 monomer is a molecule of 94 amino acids (based on a molecular weight estimate of 10 kDa) with a composition resembling that previously published for allergen A. The first 10 amino acids are identical to those of a protein affinity purified from the body fluid of Ascaris suum at the Wellcome Laboratories for Experimental Parasitology (WLEP-14K). The similarity between ABA-1 and WLEP-14k is also apparent on SDS-PAGE.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Biochem Parasitol 1990 Mar
PMID:Identification of the major Ascaris allergen and its purification to homogeneity by high-performance liquid chromatography. 169 Aug 56

Reduction of turgor in pea shoots caused the accumulation of several poly(A) RNAs. cDNA clones derived from three different poly(A) RNAs which accumulate in wilted pea shoots were isolated, sequenced and expression of the corresponding genes examined. Clone 7a encoded a 289 amino acid protein. The C-terminal 180 amino acids of this protein were homologous to soybean nodulin-26. RNA hybridizing to cDNA 7a was abundant in roots, and induced in shoots by dehydration, heat shock and to a small extent by ABA. Hydropathic plots indicate that the protein encoded by cDNA 7a contains six potential membrane spanning domains similar to proteins which form ion channels. Clone 15a encoded a 363 amino acid protein with high homology to cysteine proteases. RNA hybridizing to cDNA 15a was more abundant in roots than shoots of control plants. Dehydration of pea shoots induced cDNA 15a mRNA levels whereas heat shock or ABA treatment did not. Clone 26g encoded a 508 amino acid protein with 30% residue identity to several aldehyde dehydrogenases. RNA hybridizing to cDNA 26g was induced by dehydration of shoots but not roots and heat shock and ABA did not modulate RNA levels. Levels of the three poly(A) RNAs increased 4-6-fold by 4 h after wilting and this increase was not altered by pretreatment of shoots with cycloheximide. When wilted shoots were rehydrated, RNA hybridizing to cDNA 26g declined to pre-stress levels within 2 h. Run-on transcription experiments using nuclei from pea shoots showed that transcription of the genes which encode the three poly(A) RNAs was induced within 30 min following reduction of shoot turgor. One of the genes showed a further increase in transcription by 4 h after dehydration whereas transcription of the other 2 genes declined. These results indicate that plant cells respond to changes in cell turgor by rapidly increasing transcription of several genes. Furthermore, the expression of the turgor-responsive genes varies with respect to the time course of induction and reversibility of the wilting-induced changes.
Plant Mol Biol 1990 Jul
PMID:Turgor-responsive gene transcription and RNA levels increase rapidly when pea shoots are wilted. Sequence and expression of three inducible genes. 171 81

A cDNA clone (pMA2005) of a Group 3 LEA (late embryogenesis abundant) protein has been sequenced from wheat. The wheat cDNA clone codes for a protein with ten tandem repeats of an 11 amino acid sequence and has homology to other Group 3 LEAs reported in barley, carrot, cotton and rape (L. Dure et al., Plant Mol Biol 12: 475-486, 1989). The deduced amino acid sequence indicates that the wheat protein has a molecular weight of 23,000 and is a basic, hydrophilic protein. Northern analysis with the cDNA clone shows that dehydration of wheat shoot tissue results in increased transcript levels that correlate with increases in endogenous ABA.
Plant Mol Biol 1991 Jun
PMID:Sequence analysis of a cDNA encoding a group 3 LEA mRNA inducible by ABA or dehydration stress in wheat. 183 Aug 22


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