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)

Eschscholtzia californica stigmas with germinating pollen at different stages of development were the subject of histochemical studies which aimed the localization of several enzymes like phosphorylase, leucine amino peptidase, nonspecific esterase, cytochrome oxidase, aldolase, alpha-glycerophosphate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, monoamine oxidase, alpha-galactosidase, beta-glucosidase and beta-galactosidase. Pollen and pollen tubes were shown to contain starch, lipid, proteins and soluble sugars as the storage products. These storage products were utilized during germination and tube growth. The role of different enzymes in the process of germination and tube growth is discussed. From the distribution of oxidoreductases it is inferred that respiration plays an essential role in the tube growth. During pollen germination probably the reserve proteins were transported to pollen tube tip. The increase of activity of alpha-and beta-galactosidase in pollen tubes indicates on their involvement in carbohydrate metabolism. The role of alpha-galactosidase in the metabolism of galactolipids is also inferred. Similarly, the reaction catalysed by beta-glucosidase resulted in the production of aglycon and glucose; of these the former possibly act as a substrate of peroxidase. Some of the glycosidases diffused out of pollen wall on the stigma and participated in the release of free sugars of the female tissue.
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PMID:Studies on the physiology of pollen and pollen tube growth. IV Eschscholtzia californica Cham. 22 Jan 58

Although the cesarean section rate has increased steadily for the past 12 years, further increase seems unlikely since the indications for performing the operation are already broadly defined. Most of the earlier indications will remain unchanged (eg, the presence of placenta previa and cephalopelvic disproportion). The trend toward vaginal delivery in perhaps 30% to 40% of breech births will probably have no material effect on the number of cesarean sections performed, and the present use of cesarean section for multiple pregnancy will probably continue. The two conditions under which cesarean section rates might become significantly lower are (1) automatic repeat cesarean section (which now accounts for more than 25% of all cesarean sections), a procedure which will probably decline as increasing numbers of such women have vaginal deliveries, and (2) a redefinition of the present midforceps classification, which will permit some of the easy midforceps deliveries from a low level to be performed without the legally abhorrent stigma of mid-forceps delivery. The value of prophylactic antibiotics for women predisposed to infection has now been proved, and further placebo studies to demonstrate this are not warranted. In the past, "type and match 2 units" was a routine prelude to cesarean section, and for every unit of blood transfused to cesarean section patients, some 25 units were cross-matched and held in (unnecessary) readiness. This formula is gradually giving way to type and screen, eliminating countless crossmatches. Because of possible harmful fetal effects, preoperative fluid loading, a necessary part of conduction anesthesia, is changing from the customary 5% glucose to the use of fluids containing no glucose. It has been suggested that conduction anesthesia may not offer unlimited time for cesarean section, as used to be thought. Apgar scores are lower if the time from uterine incision to delivery is longer than three minutes, a diminution that may be a function of the anesthesia or may reflect difficulty in delivery. Cesarean section mortality is much lower than it was in former years, but one may expect from one to two deaths per 1,000 operations. Overall, the maternal mortality from cesarean section per se is probably from three to five times higher than that of vaginal delivery (in one series, 11.5 times higher than vaginal delivery). The incidence of mild, transient respiratory signs in the newborn is higher after cesarean than after vaginal delivery, and the incidence of respiratory distress syndrome is also slightly higher.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Cesarean section. 388 13

In plants, the pollen coat covers the exine wall of the pollen and is the outermost layer that makes the initial contact with the stigma surface during sexual reproduction. Little is known about the constituents of the pollen coat, especially in wind-pollinated species. The pollen coat was extracted with diethyl ether from the pollen of maize (Zea mays L.), and a predominant protein of 35 kDa was identified. On the basis of the N-terminal sequence of this protein, a cDNA clone of the Xyl gene was obtained by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequence of the 35-kDa protein shared similarities with the sequences of many microbial xylanases and a barley aleurone-layer xylanase. The 35-kDa protein in the pollen-coat extract was purified to homogeneity by fast protein liquid chromatography and determined to be an acidic endoxylanase that was most active on oat spelt xylan. Northern and in situ hybridization showed that Xyl was specifically expressed in the tapetum of the anther after the tetrad microspores had become individual microspores. Southern hybridization and gene-copy reconstruction studies showed only one copy of the Xyl gene per haploid genome. Analyses of the genomic DNA sequence of Xyl and RNase protection studies with the transcript revealed many regulatory motifs at the promoter region and an intron at the 5' leader region of the transcript. The Xyl transcript had a 562-nucleotide (nt) 5' leader, a 54-nt sequence encoding a putative signal peptide, a 933-nt coding sequence, and a 420-nt 3'-untranslated sequence. The unusually long 5' leader had an open reading frame encoding a putative 175-residue protein whose sequence was most similar to that of a microbial arabinosidase. The maize xylanase is the first enzyme documented to be present in the pollen coat. Its possible role in the hydrolysis of the maize type II primary cell wall (having xylose, glucose, and arabinose as the major moieties) of the tapetum cells and the stigma surface is discussed.
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PMID:The predominant protein on the surface of maize pollen is an endoxylanase synthesized by a tapetum mRNA with a long 5' leader. 1042 75

Floral biology and breeding behavior were studied in the bamboo Dendrocalamus strictus Nees. The inflorescence in this species is a large branching panicle. Fertile florets are intermixed with smaller sterile ones. There are six stamens. The ovary is stipitate and turbinate. The style is long and the stigma is bifid and plumose. Dendrocalamus strictus is typically dichogamous and protogynous. The gynoecium matures 3-4 days before the androecium, effectively preventing self pollination. Flower bloom, which took place over a period of 2 to 3 h, was dependent on air temperature and only occurred between 0600 and 1300 h. Dendrocalamus strictus is anemophilous. Flowers in the male phase were visited by insects. These insects completely neglected the flowers at the female phase. The insects fed on the pollen and were not pollen vectors. When wind was excluded by enclosing the inflorescences in bags there was no seed set, indicating that cross pollination by wind is necessary for fertilization and that parthenocarpy and apomixis are not occurring in this species. Pollen fertility was about 98% as indicated by staining fresh pollen at the time of anther dehiscence and pollen release with Alexander's stain (Alexander 1969). When placed on a modified Brewbaker-Kwak medium containing 1% glucose, the pollen grains germinated well, and the pollen tubes grew to 15-20 times the diameter of mature pollen grains. Although profound protogyny has its disadvantages in times of sporadic flowering, it can be useful in breeding programs because it eliminates the need for emasculation.
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PMID:Floral biology and breeding behavior in the bamboo Dendrocalamus strictus Nees. 1496 95

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

Weight gain is associated with the use of many psychotropic medications, including antidepressants, mood stabilizers, antipsychotic drugs, and may have serious long term consequences: it can increase health risks, specifically from overweight (BMI = 25-29.9 kg/m2) to obesity (BMI > or =30 kg/m2), according to Body Mass Index (BMI), and the morbidity associated therewith in a substantial part of patients (hypertension, coronary heart desease, ischemic stroke, impaired glucose tolerance, diabetes mellitus, dyslipidemia, respiratory problems, osteoarthritis, cancer); according to patients, psychosocial consequences such as a sense of demoralization, physical discomfort and being the target of substantial social stigma are so intolerable that they may discontinue the treatment even if it is effective. The paper reviews actual epidemiological data concerning drug induced weight gain and associated health problems in psychiatric patients : there is a high risk of overweight, obesity, impaired glucose tolerance, diabetes mellitus, premature death, in patients with schizophrenia or bipolar disorder; and the effects of specific drugs on body weight: Tricyclic Antidepressants (TCA) induced weight gain correlated positively with dosage and duration of treatment, more pronounced with amitriptyline ; Selective Serotonin Reuptake Inhibitors (SSRI) decrease transiently bodyweight during the first few weeks of treatment and may then increase bodyweight; weight gain appears to be most prominent with some mood stabilizers (lithium, valproate); atypical antipsychotics tend to cause more weight gain than conventional ones and weight gain, diabetes, dyslipidemia, seem to be most severe with clozapine and olanzapine. Conceming the underlying mechanisms of drug induced weight gain, medications might interfere with central nervous functions regulating energy balance; patients report about: increase of appetite for sweet and fatty foods or "food craving" (antidepressants, mood stabilizers, antipsychotic drugs) and weight gain despite reduced appetite which can be explained by an altered resting metabolic rate (TCA, SSRI, Monoaminoxidase Inhibitors MAO I). According to current concepts, appetite and feeding are regulated by a complex of neurotransmitters, neuromodulators, cytokines and hormones interacting with the hypothalamus, including the leptin and the tumor necrosis factor system. The pharmacologic mechanisms underlying weight gain are presently poorly understood: maybe the different activities at some receptor systems may induce it, but also genetic predisposition. Understanding of the metabolic consequences of psychotropic drugs (weight gain, diabetes, dyslipidemia) is essential: the insulin-like effect of lithium is known; treatment with antipsychotic medications increases the risk of impaired glucose tolerance and diabetes mellitus. Several management options of weight gain are available from choosing or switching to another drug, dietary advices, increasing physical activities, behavioural treatment, but the best approach seems to attempt to prevent the weight gain : patients beginning maintenance therapy should be informed of that risk, and nutritional assessment and counselling should be a routine part of treatment management, associated with monitoring of weight, BMI, blood pressure, biological parameters (baseline and three months monitoring of fasting glucose level, fasting cholesterol and triglyceride levels, glycosylated haemoglobin). Psychiatrics must pay attention to concomitant medications and individual factors underlying overweight and obesity. Weight gain has been described since the discovery and the use of the firstpsychotropic drugs, but seems to intensify with especially some of the second generation antipsychotic medications ; understanding of the side effects of psychotropic drugs, including their metabolic consequences (weight gain, diabetes, dyslipidemia) is essential for the psychiatrics to avoid on the one hand a risk of lack of compliance, a discontinuation of the pharmacological medication and also a risk of relapse and rehospitalization, and on the other hand to avoid acute life threatening events (diabetic ketoacidocetosis and non ketotic hyperosmolar coma, long term risk complications of diabetes and overweight).
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PMID:[Psychotropic drugs induced weight gain: a review of the literature concerning epidemiological data, mechanisms and management]. 1638 18

Male-female recognition in flowering plants is initiated by mutual contact of pollen and stigma surface components. Analysis of the surface macromolecules of both stigma and pollen of Gladiolus gandavensis revealed a complex mixture of proteins, glycoproteins, and glycolipids. The carbohydrate-containing components amounted to 6% in pollen and 23% in stigma and contained the monosaccharides galactose, arabinose, glucose, mannose, and rhamnose. All the mannose of both preparations was associated with a fraction that bound to concanavalin A. The stigma surface contained an arabinogalactan or arabinogalactan protein as a major component. This component has been isolated by affinity chromatography on tridacnin-Sepharose and shown to be similar in composition to a style canal component isolated in the same way. The capacity of the stigma surface preparations to bind nonspecifically to macromolecules from pollen and other sources has been demonstrated in vivo and in vitro. Specific binding of concanavalin A to the stigma surface decreases the adhesive capacity for pollen protein. The arabinogalactan of the stigma surface may act as an adhesive base. The pollen and stigma surfaces apparently complement one another to provide all the components of an ideal adhesive.
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PMID:Pollen-stigma interactions: Identification and characterization of surface components with recognition potential. 1659 78

A quantity of labeled stigmatic exudate, collected from detached Lilium longiflorum (cv. Ace) pistils labeled with d-glucose-1-(14)C, was fractionated on Sephadex G-100 and the polysaccharide component, G-100-I, was injected into the hollow styles of unlabeled detached pistils (cv. Ace) which had been removed on the day after anthesis from the plant. Injected pistils were immediately cross-pollinated with L. longiflorum (cv. No. 44) pollen. Eighty-four hours later, pistils were dissected to recover the pollen tubes, expended exudate, and labeled tissues of the stigma and style. Distribution of label revealed that at least 25% of the carbohydrate substance in excised pollen tubes was derived from G-100-I. The composition of expended exudate adhering to pollen tubes, of pollen tube cytoplasm, and of pollen tube walls suggests that utilization of exudate by growing pollen tubes involves uptake and incorporation into pollen tube cytoplasm of exudate polysaccharide fragments followed by extensive metabolism of at least a portion of the incorporated carbohydrate prior to its utilization for pollen tube wall biosynthesis. Results suggest the presence of at least two polysaccharide components in G-100-I, one which resists major degradation following injection into the style and another which undergoes measurable degradation both before and after entry into the pollen tube.
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PMID:The Nutritional Role of Pistil Exudate in Pollen Tube Wall Formation in Lilium longiflorum: I. Utilization of Injected Stigmatic Exudate. 1665 36

Pollen accumulates starch reserves during development and the final stage of ripening. Before the anther opens, starch is totally or partially converted to pectins, glucose, fructose, sucrose, and to some unknown polysaccharides. Pollen is exposed to dispersing agents in an arrested developmental state which differs according to pollen water content. Pollen is classified as partially dehydrated or partially hydrated. The final water content may be reached before or after anther opening. Especially during exposure and dispersal, partially dehydrated pollen may interconvert soluble and insoluble reserves, modifying internal turgor pressure and hindering water loss or gain. Partially hydrated pollen is commonly devoid of mechanisms to conserve viability in time but has the advantage of quickly emitting pollen tubes on reaching the stigma.
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PMID:Pollen carbohydrates and water content during development, presentation, and dispersal: a short review. 1693 57

Cell wall hydrolases are well documented to be present on pollen, but their roles on the stigma during sexual reproduction have not been previously demonstrated. We explored the function of the tapetum-synthesized xylanase, ZmXYN1, on maize (Zea mays L.) pollen. Transgenic lines (xyl-less) containing little or no xylanase in the pollen coat were generated with use of an antisense construct of the xylanase gene-coding region driven by the XYN1 gene promoter. Xyl-less and wild-type plants had similar vegetative growth. Electron microscopy revealed no appreciable morphological difference in anther cells and pollen between xyl-less lines and the wild type, whereas immunofluorescence microscopy and biochemical analyses indicated an absence of xylanase on xyl-less pollen. Xyl-less pollen germinated as efficiently as wild-type pollen in vitro in a liquid medium but less so on gel media of increasing solidity or on silk, which is indicative of partial impaired water uptake. Once germinated in vitro or on silk, the xyl-less and wild-type pollen tubes elongated at comparable rates. Tubes of germinated xyl-less pollen on silk did not penetrate into the silk as efficiently as tubes of wild-type pollen, and this lower efficiency could be overcome by the addition of xylanase to the silk. For wild-type pollen, coat xylanase activity on oat spelled xylan in vitro and tube penetration into silk were inhibited by xylose but not glucose. The overall findings indicate that maize pollen coat xylanase facilitates pollen tube penetration into silk via enzymatic xylan hydrolysis.
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PMID:Maize pollen coat xylanase facilitates pollen tube penetration into silk during sexual reproduction. 1706 71


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