Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0277787 (stigma)
 13,352 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Linkages with isozymic loci facilitate the investigation of certain classes of genetic variation. Due to the mapping of 20 isozymic loci on nine of the 12 chromosomes of the cultivated tomato (Lycopersicon esculentum), much progress has been made in these applications, particularly in the analysis of interspecific hybrids. Isozymes can expedite the selective elimination of inferior wild parent germ plasm in backcross transfer of desired genes to the cultivated parent. Allelic isozyme constitution also aids in identification of lines, particularly in evaluating the purity of F1 hybrid cultivars. Advantages that isozymes impart to such investigations are: (1) unequivocal classification of phenotypes, (2) detection of heterozygotes, (3) lack of epistasis between isozyme loci, (4) lack of effect of allelic isozymes per se on morphology or physiology, (5) prolific source of monogenic markers, and (6) phenotyping at early developmental stages. Each of these attributes can be exploited to great advantage, but collectively they constitute a formidable argument for monitoring genetic variation by means of isozymes. Linkages between isozyme loci and qualitative loci can be exploited as in the monitoring of Mi (gene for root-knot nematode resistance derived from L peruvianum) by the very tightly linked Aps-1(1); in similar fashion, Prx-2(1) serves as a useful marker for ms-10 (male sterility). Asp-1 monitoring in the former is more reliable than testing for nematode resistance per se; codominance of Prx-2 alleles of the latter solves problems incurred by the recessiveness of ms-10; in both instances phenotypes can be ascertained at earlier growth stages for isozymes than for economic traits. In the first backcross of the interspecific hybrid L esculentum x Solanum pennellii to the former, the segregation of four quantitative traits was monitored by allelic isozymes at 12 loci, situated on at least eight chromosomes, covering approximately 60% of the known tomato genome. At least five quantitative trait loci (QTL) were found to determine each of the four traits. Each parent contributes alleles with positive as well as negative effects, the greatest balance for stigma exsertion, the trait also exhibiting the greatest extent of transgressive segregation. Three pairs of linked isozymic loci permitted a crude form of three-point mapping of the associated QTL. interactions between QTL linked with pairs of isozymic genes were tested in all possible combinations; 18 of the 274 comparisons showed significant interactions, indicating epistasis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Isozyme monitoring of genetic variation in Lycopersicon. 664 90

A gene encoding a 40.3-kDa serine proteinase inhibitor (PI) precursor is expressed at high levels in the stigma of the ornamental tobacco, Nicotiana alata. The precursor is processed proteolytically in vivo to release five homologous proteinase inhibitors of approximately 6 kDa, as well as two flanking peptides. The five PIs have been purified from stigmas and identified by N-terminal sequencing, electrospray mass spectrometry and inhibition activity against chymotrypsin or trypsin. One of the PIs inhibits chymotrypsin and the other four are most active on trypsin. Cleavage occurs in a linker region (EEKKND) that is repeated six times in the precursor molecule. In the plant, the initial cleavage probably occurs between asparagine and the aspartate residues and ragged ends are formed by subsequent trimming. In vitro, the protease-sensitive linker region is selectively cleaved by the endoproteinases Asp-N, Glu-C and Lys-C to release fully active approximately 6-kDa PIs that are resistant to further proteolytic digestion. The precursor, produced by a recombinant baculovirus, inhibits chymotrypsin more effectively than trypsin. The stoichiometry of 2.6 trypsin molecules/1 precursor molecule indicates that processing is required to activate or expose all of the four trypsin inhibitory sites.
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PMID:Characterization of the protease processing sites in a multidomain proteinase inhibitor precursor from Nicotiana alata. 760 Nov 8

The distribution of integrin-like proteins in the pollen tube was examined by immunofluorescent labeling and western blotting techniques using antibodies against human placenta integrin vitronectin receptor (VnR), and alpha(v), beta3 and beta1 integrin subunits. Pseudocolor-coded confocal images showed intense immunostaining within 10 and 5 microm of the tip of the pollen tube in Lilium davidii and Nicotiana tabacum respectively. In both segments the site near the plasma membrane was labeled. Western blotting analyses revealed cross-reaction of anti-beta3, anti-alpha(v) and anti-VnR with the proteins in the plasma membrane preparation of L. davidii and Hemerocallis citrina pollen tube. These studies provide evidence for the first time that the integrin-like protein is present in pollen tubes, and it may be mainly composed of alpha(v) and beta3 subunits in lily pollen tubes. In a functional assay, neither anti-VnR antibody nor the Arg-Gly-Asp-Ser tetrapeptide inhibited pollen tube growth of N. tabacum in vitro, but both of them depressed tube growth on the stigma and in style under quasi in vivo culture conditions. The integrin-like proteins localized in the tip and periphery of the pollen tube appeared to play roles in growth of the pollen tube tip and interaction with the extracellular matrix of the style.
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PMID:Integrin-like proteins in the pollen tube: detection, localization and function. 1114 72

Pollen tube elongation is a polarized cell growth process that transports the male gametes from the stigma to the ovary for fertilization inside the ovules. Actomyosin-driven intracellular trafficking and active actin remodeling in the apical and subapical regions of pollen tubes are both important aspects of this rapid tip growth process. Actin-depolymerizing factor (ADF) and cofilin are actin binding proteins that enhance the depolymerization of microfilaments at their minus, or slow-growing, ends. A pollen-specific ADF from tobacco, NtADF1, was used to dissect the role of ADF in pollen tube growth. Overexpression of NtADF1 resulted in the reduction of fine, axially oriented actin cables in transformed pollen tubes and in the inhibition of pollen tube growth in a dose-dependent manner. Thus, the proper regulation of actin turnover by NtADF1 is critical for pollen tube growth. When expressed at a moderate level in pollen tubes elongating in in vitro cultures, green fluorescent protein (GFP)-tagged NtADF1 (GFP-NtADF1) associated predominantly with a subapical actin mesh composed of short actin filaments and with long actin cables in the shank. Similar labeling patterns were observed for GFP-NtADF1-expressing pollen tubes elongating within the pistil. A Ser-6-to-Asp conversion abolished the interaction between NtADF1 and F-actin in elongating pollen tubes and reduced its inhibitory effect on pollen tube growth significantly, suggesting that phosphorylation at Ser-6 may be a prominent regulatory mechanism for this pollen ADF. As with some ADF/cofilin, the in vitro actin-depolymerizing activity of recombinant NtADF1 was enhanced by slightly alkaline conditions. Because a pH gradient is known to exist in the apical region of elongating pollen tubes, it seems plausible that the in vivo actin-depolymerizing activity of NtADF1, and thus its contribution to actin dynamics, may be regulated spatially by differential H(+) concentrations in the apical region of elongating pollen tubes.
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PMID:The regulation of actin organization by actin-depolymerizing factor in elongating pollen tubes. 1221 14

Aspartic proteinases from flowers of Cynara cardunculus have been extensively studied and long used as coagulants in the manufacture of several traditional Spanish and Portuguese cheeses. These endopeptidases are called cardosins or cynarases, depending on the authors. However, the proteinases of another plant of the genus Cynara, the artichoke (Cynara scolymus), are less known, probably because the flower of this plant is usually consumed as a vegetable. In the study described here, three proteinases (cynarases A, B and C) with milk-clotting properties were purified from the stigma of artichoke. All three proteinases are glycoproteins and composed of a one large and one small subunit. The enzymatic properties of cynarase A, a glycoprotein containing N-linked high mannose type glycans, which express maximum activity at pH 5.0 and 70 degrees C, were studied in detail. Catalytic and inhibition studies indicated that this cynarase is of the aspartic acid type. The results indicate artichoke extract could also be used in the milk industry in the same way as the extract obtained from the flower of C. cardunculus.
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PMID:Purification of cynarases from artichoke (Cynara scolymus L.): enzymatic properties of cynarase A. 1564 9

The spadix of skunk cabbage, Symplocarpus foetidus, is thermogenic and maintains an internal temperature of around 20 degrees C even when the ambient air temperature drops below freezing. This homeothermic heat production is observed only during the stigma stage, and thereafter ceases at the male stage when pollen is shed. To clarify the regulatory mechanism by which the stigma stage-specific heat production occurs in the spadix, sugars, organic acids, and amino acids in xylem sap were analyzed and compared with those of post-thermogenic plants. Interestingly, no significant difference was observed in the total volume of xylem sap per fresh weight of the spadix between thermogenic (31.2+/-24.7 microl h(-1) g(-1)) and post-thermogenic (50.5+/-30.4 microl h(-1) g(-1)) plants. However, concentrations of sugars (sucrose, glucose, and fructose), organic acids (malate and succinate), and amino acids (Asp, Asn, Glu, Gln, Gly, and Ala) in xylem sap decreased remarkably in post-thermogenic plants. Our results indicate that the composition of the xylem sap differs during the development of the spadix of S. foetidus.
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PMID:Changes in the composition of xylem sap during development of the spadix of skunk cabbage (Symplocarpus foetidus). 1597 47