Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Pollen development”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed2001

Automatic mass-rearing of Amblyseius womersleyi (Acari: Phytoseiidae).

Using incorporated devices, Tetranychus urticae spider mites were rinsed from hydroponically-grown lima bean plants, collected, separated and blow-dried. This yielded a reliable and large volume of eggs and larvae, which were fed to Amblyseius womersleyi rearings on 15 x 5 cm2 polyethylene arenas. Of several feeding regimes tested, daily feeding of 10 mg T. urticae eggs and larvae resulted in the highest predator population levels. The best harvest period was between 15 and 27 days, when predator density exceeded 600 mites per arena. A preliminary automatic mass-rearing device was tested for A. womerslyi. This incorporated both rearing and harvesting procedures. A micro-feeder was developed to supply the required volume of spider mites and maize pollen (1:1 mixture) to the predators. A Bakelite rearing arena reduced the space requirements of a polyethylene arena, was more durable and an essential component in the automatic mass-rearing and harvesting. Mite harvesting is carried out through the use of a vacuum-head harvester. Supplements of (sterilized) spider mites, pollen, vermiculite and wheat bran are automatically added to the predators. The devices for harvesting, filling and packing are incorporated and synchronized and the entire system is controlled by a single slide-switch. The design and system can be expanded without changing the basic processes and program, for example to adopt it for other species of predaceous mites.

Animal Husbandry↗
PubMed2000

Evolution and maintenance of stigma-height dimorphism in Narcissus. I. Floral variation and style-morph ratios.

An unusual stylar dimorphism occurs in Narcissus, a plant genus of insect-pollinated Mediterranean geophytes. To determine the characteristics of the sexual polymorphism, we investigated floral variation in 46 populations of N. assoanus (section Jonquillae) and 21 populations of N. dubius (section Tazettae) in SW France. Flowers possess two stamen levels in each morph that occupy slightly different positions within the floral tube. In long-styled plants (L-morph), the stigma is located within or slightly above the upper-level stamens, whereas in short-styled plants (S-morph) the stigma is placed well below the lower-level stamens. The stigma-height dimorphism is distinct from heterostyly because the reciprocity of stigma and anther positions in the two style morphs is only weakly developed and there are no differences between the style morphs in pollen size or production. In both species, mean stigma-anther separation is much greater in the S-morph than the L-morph. In N. assoanus, population style-morph ratios vary from isoplethy (1L:1S) to L-biased, whereas in N. dubius they are usually strongly L-biased or occasionally contain only the L-morph. Populations fixed for the S-morph, or with S-biased morph ratios, were not observed. In N. assoanus, style-morph ratios were associated with population size: large continuous populations always exhibited 1:1 morph ratios, whereas smaller, fragmented populations were often L-biased. This pattern was not evident in N. dubius. We argue that biased style-morph ratios largely result from morph-specific differences in assortative mating.

Biological Evolution↗
PubMed2003

Enhanced formation of flowers in salt-stressed Arabidopsis after genetic engineering of the synthesis of glycine betaine.

Previously, we showed that transformation with the codA gene for choline oxidase allows plants to synthesize glycine betaine (GB) and enhances their ability to tolerate various kinds of stress during germination and vegetative growth. In this study, we examined the tolerance of transformed plants to salt stress at the reproductive stage, which is the stage at which plants are most sensitive to environmental stress. Salt-shock treatment of wild-type plants for 3 days resulted in the abortion of flower buds and decreased the number of seeds per silique. These deleterious effects were clearly visible 6 days after the termination of salt-shock treatment. Microscopic examination of floral structures revealed that salt stress inhibited the development of anthers, pistils, and petals. In particular, the production of pollen grains and ovules was dramatically inhibited. These effects of salt stress were significantly reduced by transformation with the codA gene, and our observations suggested that the enhanced tolerance of the transgenic plants was a result of the accumulation of GB in the reproductive organs. Indeed, levels of GB in flowers, siliques, and inflorescence apices were about five times higher than in leaves.

Arabidopsis↗
PubMed1986

Arabinogalactan-Proteins of the Female Sexual Tissue of Nicotiana alata: I. Changes during Flower Development and Pollination.

Arabinogalactan-proteins (AGPs), isolated from the pistils of Nicotiana alata, an ornamental tobacco, are developmentally regulated. Both the total amount and concentration of AGP in the stigma increase during flower development, reaching 10 micrograms AGP/stigma at maturity. In contrast, AGP concentration in the style remains constant throughout the maturation period reaching 12 micrograms AGP/style at maturity. The classes of AGP present in the stigma and style during flower development, separated according to their charge by crossed-electrophoresis, are different and change during development. Pollination of flowers of N. alata with compatible or incompatible pollen results in a significant and reproducible increase in the amount of AGPs in the stigma, but not the style, compared with control unpollinated pistils. Pollination with ethanol vapor inactivated pollen also results in an increase in the amount of AGP in the stigma, but this is less than half that observed following pollination with viable pollen. There are no significant differences in the classes of AGP, based on crossed-electrophoresis, present in the pistil following pollination.

Journal Article↗
PubMed1985

Characterization of allergens and patient sera by a nitrocellulose immunoprint technique.

A rapid and convenient protein-gel blot technique for qualitative detection of antigens/allergens in pollen allergen extracts and IgE/IgG antibodies in patient sera has been developed. The antigens were separated by isoelectric focusing in agarose gel and transferred to nitrocellulose by capillary migration. After incubation of the nitrocellulose strips with serum from allergic patients, the binding of the patient's specific IgE or IgG antibodies was analyzed by using isotope-labelled or enzyme-labelled anti-IgE or anti-IgG. The time needed for detection with isotope-labelled antibody was approximately 20 h and with enzyme-labelled antibody 2 h. The immunoprint technique is easy to use, which renders it suitable for routine use in allergy research and quality control.

Allergens↗
PubMed2004

[The roles of arabinogalactan-proteins in sexual reproduction of angiosperms].

Arabinogalactan-proteins (AGPs) are a class of proteoglycans distributed mainly in the cell surfaces and extracellular matrix of most plants. Their numerous expressions have been detected in many male reproductive organs (pollen, pollen tube and sperm), female reproductive organs (stigma, style and ovary) and embryos (zygotic and somatic embryos) in many plants. Numerous investigations have demonstrated that AGPs are involved in the process of sexual reproduction of angiosperms and play multiple roles, e.g., providing surface adhesion, nutrients and directional cues or signals for pollen tubes. They may also participate in gametal recognition and embryo development and differentiation. But the mechanisms underlying these roles of AGPs are still unclear. Knowledge of AGPs in the structural components, characteristics, expression in reproductive tissues during the process of reproduction are summarized and the mechanisms underlying their functioning are discussed.

Magnoliopsida↗
PubMed1985

Tissue culture experiments on the vegetative micropropagation of oak.

Excised parts of juvenile green stem, seedlings growing out from unripe acorns and epicotyl segments of seedlings proved to be the best inocula for vegetative micropropagation under the given conditions. By means of interactions between mineral nutrients and supplementary regulators, callus, shoots (shoot sprouting) and regeneration of plantlets were induced from such explants. In the morphology of regeneration, the type of oak inocula rather than the basal medium played a primary role in the experiments described, the latter being just an influencing factor. No regeneration could be induced from resting buds of shoot, meristem tips of axillary buds, anthers or pollen, under the experimental conditions applied. Results obtained, in a further developed form, seem to be suitable for vegetative micropropagation of oaks.

Culture Media↗
PubMed1995

The kinetics of the cytologic and rhinomanometric changes in the nose after challenge with allergen.

The objective of these experiments was to study the dynamics of the cytologic and rhinomanometric nasal reaction after allergen challenge. For this purpose a micro-suction system was developed to repetitively and atraumatically collect nasal secretions. Outside of the pollen season, four patients allergic to grass pollen were challenged with phosphate buffered saline (PBS) and, two weeks later, with grass pollen. Six control subjects were challenged with PBS only. Repetitive nasal secretion samplings over three days and rhinomanometry (PAR) were performed. Analysis of samplings taken before allergen challenge proved the atraumatic character of the micro-suction and provocation methods. Coupling the obtained dynamic data of nasal cytology and PAR, the following observations could be made: 1) Higher number of eosinophils in patients in the absence of antigen, compared to controls, suggesting a constitutional characteristic of atopy. 2) A close temporal association between cytological and clinical events occurring during the late phase of the allergic reaction. Nasal obstruction seems to be correlated with the influx of eosinophils rather than with their absolute concentration.

Adult↗
PubMed1994

[Enzyme-linked immunosorbent assay for the quantification of Cry j I and Cry j II].

Enzyme-linked immunosorbent assays (ELISA) were developed to specifically quantify the two major allergens from Japanese cedar pollen, Cry j I and Cry j II. Polystyrene microplates coated with antibodies specific for Cry j I or Cry j II were incubated with an allergen and then with biotinylated anti-Cry j I or Cry j II antibody. The bound allergen-biotin Ab complexes were detected with HRPO-conjugated streptavidin and an enzyme substrate. The working ranges of Cry j I ELISA and Cry j II ELISA were 0.3-20 ng/ml and 0.6-20 ng/ml, respectively. Intra- and inter-assay coefficients of variation for reproducibility were 1.5-10.3% and 0.9-12.9%. These ELISA systems showed no cross-reactivity between Cry j I and Cry j II and showed little cross-reactivity with pollen allergens of plants botanically related to the Japanese cedar. Using the Cry j I ELISA and the Cry j II ELISA, it was possible to quantify Cry j I and Cry j II easily and accurately. These ELISA systems will be useful in various fields, especially for the analysis and standardization of the allergens necessary for diagnosis and treatment of Japanese cedar pollinosis.

Allergens↗
PubMed2006

Lactoferrin decreases pollen antigen-induced allergic airway inflammation in a murine model of asthma.

Pollen grains contain reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and in contact with mucosal surfaces generate superoxide anion (O2*-). In the presence of iron, O2*- may be converted to more reactive oxygen radicals, such as to H2O2 and/or *OH, which may augment antigen-induced airway inflammation. The aim of the study was to examine the impact of lactoferrin (LF), an iron-binding protein, on ragweed (Ambrosia artemisiifolia) pollen extract (RWE)-induced cellular oxidative stress levels in cultured bronchial epithelial cells and accumulation of inflammatory and mucin-producing cells in airways in a mouse model of allergic airway inflammation. Results show that LF lowered RWE-induced increase in cellular reactive oxygen species (ROS) levels in bronchial epithelial cells. Most importantly, LF significantly decreased accumulation of eosinophils into airways and subepithelium of intranasally challenged, sensitized mice. LF also prevented development of mucin-producing cells. Amb a 1, the major allergenic ragweed pollen antigen lacking NADPH oxidase activity, induced low-grade airway inflammation. When administered along with glucose oxidase (G-ox), a superoxide-generating enzyme, Amb a 1 induced robust airway inflammation, which was significantly lowered by LF. Surprisingly, LF decreased also inflammation caused by Amb a 1 alone. Iron-saturated hololactoferrin had only a marginal effect on RWE-induced cellular ROS levels and RWE- or Amb a 1 plus G-ox-induced inflammation. We postulate that free iron in the airways chemically reduces O2*- to more reactive species which augment antigen-induced inflammation in a mouse model of asthma. Our results suggest the utility of LF in human allergic inflammatory disorders.

Allergens↗
PubMed1998

Effects of Yariv phenylglycoside on cell wall assembly in the lily pollen tube.

Arabinogalactan-proteins (AGPs) are proteoglycans with a high level of galactose and arabinose. Their current functions in plant development remain speculative. In this study, (beta-D-glucosyl)3 Yariv phenyl-glycoside [(beta-D-Glc)3] was used to perturb AGPs at the plasmalemma-cell wall interface in order to understand their functional significance in cell wall assembly during pollen tube growth. Lily (Lilium longiflorum Thunb.) pollen tubes, in which AGPs are deposited at the tip, were used as a model. Yariv phenylglycoside destabilizes the normal intercalation of new cell wall subunits, while exocytosis of the secretory vesicles still occurs. The accumulated components at the tip are segregated between fibrillar areas of homogalacturonans and translucent domains containing callose and AGPs. We propose that the formation of AGP/(beta-D-Glc)3 complexes is responsible for the lack of proper cell wall assembly. Pectin accumulation and callose synthesis at the tip may also change the molecular architecture of the cell wall and explain the lack of proper cell wall assembly. The data confirm the importance of AGPs in pollen tube growth and emphasize their role in the deposition of cell wall subunits within the previously synthesized cell wall.

Cell Wall↗
PubMed2025

Genetic effect of the Ph1 locus on transcriptome atlas of anther development-related genes, meiotic chromosome behavior and agronomic traits in bread wheat.

Proper spatiotemporal expression of meiosis-related genes (MRGs) and other male-microsporogenesis/microgametogenesis-related genes (MMRGs) is crucial for normal anther development, yet their expression patterns remain largely unknown in wheat. The Ph1 locus in wheat is known to contain the Ph1 gene that plays a dual role in promoting pairing between homologous chromosomes but repressing pairing between homoeologous chromosomes, but its genetic function is still unclear. Here, we investigated these issues by conducting a comprehensive transcriptome analysis during wheat anther development in Chinese Spring (CS) and its ph1b deletion mutant under greenhouse and field conditions. Our results revealed that MRGs and MMRGs are predominantly expressed during pre-meiosis stages, with MMRGs also being highly expressed in meiotic-II. Gene co-expression analysis showed that C2H2 and B3 transcriptional factors (TFs) are associated with MRGs, and MYB regulators interacted mainly with MMRGs during microgametogenesis. Deletion of genes within the Ph1 locus failed to induce compensatory transcriptional activation of their homoeologous counterparts, while genes outside the Ph1 locus showed environmental-specific responses, especially during meiotic-II and mature pollen stages. Notably, early disjunction of bivalent chromosomes is a primary factor leading to defective meiocytes during metaphase I. Furthermore, the ph1b deletion mutant exhibited a substantially delayed heading date, potentially contributing to environment-stable and environment-specific alterations in fertility and grain-related traits. Our study highlights the significant impact of the Ph1 locus on the transcriptome during anther development, and a previously unheeded effect on meiotic chromosome pairing and agronomic traits, suggesting potential for genetic manipulations within the Ph1 locus for wheat improvement.

Triticum↗
PubMed1990

Cutaneous granulomata complicating desensitization.

D-VAC Pollens (Bencard), a standard depot pollen vaccine, was withdrawn in the mid-1970s. We report a case in which subcutaneous granulomata developed 12 years after desensitizing injections by this product.

Adult↗
PubMed1993

Specific mitochondrial proteins in pollen: presence of an additional ATP synthase beta subunit.

A protocol was designed to obtain a pure fraction of pollen mitochondria from the diploid species Nicotiana sylvestris, the female parent of the allotetraploid Nicotiana tabacum. Most organelles were morphologically intact and able to perform in organello mitochondrial (mt) protein synthesis. As revealed by two-dimensional protein electrophoresis, numerous quantitative differences exist between leaf and pollen mt proteins. Moreover, additional mt polypeptides, named R (for reproductive), encoded by either nuclear or mitochondrial genes, are found in pollen. The most abundant R polypeptide, R1 (M(r) 53,000, pI 5.6), is nuclearly encoded, is membrane bound, and cross-reacts with an antibody directed against the beta subunit of the mt ATP synthase (ATPase). N-terminal microsequence analysis showed that the two ATPase beta subunits present in leaves (beta 1 and beta 2) and the R1 pollen-specific subunit are encoded by distinct genes. A similar additional ATPase beta subunit was observed in pollen mitochondria from Petunia, suggesting that this polypeptide is of general importance for male gametophytic development in Solanaceaes.

Amino Acid Sequence↗
PubMed2000

Unfertilized ovules of Epilobium obcordatum (Onagraceae) continue to grow in developing fruits.

To determine whether unfertilized ovules continue to grow when in an ovary containing fertilized ovules, we measured ovule lengths in developing fruits of Epilobium obcordatum that were harvested 4, 5, 8, and 10 d post pollination. We found that unfertilized ovules that were in the presence of fertilized ovules continued to grow and that there was a broad range of overlap in their sizes at all sampling times. This effect was found for two types of unfertilized ovules that occur throughout the length of the ovary: normal, unfertilized ovules, apparently bypassed by pollen tubes; and sterile ovules lacking an embryo sac. In addition, there is a position effect within developing fruits. Both fertilized and unfertilized ovules are larger at the stylar end. In six samples resulting from pollination with a single pollen tetrad, a total of 18 embryos were found, and the effect on unfertilized ovules, greatest at the stylar end, diminished with distance from the ovules with embryos. Our results are consistent with the interpretation that diffusible hormones produced by developing seeds cause nearby unfertilized ovules to grow. We conclude that caution is necessary when attempting to infer ovule fertilization histories from the appearances of ovules in developing and mature fruits. What are often inferred to be aborted seeds, in many cases, may not be seeds at all. They may be enlarged, unfertilized ovules.

Journal Article↗
PubMed2003

Imprinting in the endosperm: a possible role in preventing wide hybridization.

Reproductive isolation is considered to play a key part in evolution, and plants and animals have developed a range of strategies that minimize gene flow between species. In plants, these strategies involve either pre-zygotic barriers, such as differences in floral structure and pollen-stigma recognition, or post-zygotic barriers, which are less well understood and affect aspects of seed development ranging from fertilization to maturation. In most angiosperms, a double fertilization event gives rise to a zygote and the endosperm: a triploid tissue with an unequal parental genomic contribution, which, like the placenta of mammals, provides reserves to the developing embryo. Interestingly, many aspects of endosperm development, again like the placenta, are regulated by a range of epigenetic mechanisms that are globally termed imprinting. Imprinted genes are characterized by their uniparental expression, the other parental allele being silenced. Normal development of the endosperm thus requires a highly specific balance of gene expression, from either the maternal or paternal genomes. Any alteration of this balance resulting from changes in allelic copy number, sequence or epigenetic imprints can cause endosperm failure and eventual seed abortion. In its widest sense, the endosperm thus serves as an accurate 'sensor' of compatibility between parents. A first step in understanding this important, yet complex system must clearly be the isolation and characterization of as wide a range as possible of imprinted genes.

Crosses, Genetic↗
PubMed1995

[Sensitization and onset of Japanese cedar pollinosis in children].

Recently, increases in cases of Japanese cedar pollinosis have been found, especially in children. School children, junior high school students and high-school students in Mibu-machi, Tochigi prefecture were given questionnaires, rhinoscopic examinations were done and nasal secretions and blood samples were taken. The following results for the process of sensitization and the onset of Japanese cedar pollinosis were found. According to the questionnaire, the percentage of positive Japanese cedar pollinosis was about 10% in 6-year-olds and about 25% in 17-year-olds. However, according to the blood samples, Japanese cedar pollen antibodies abruptly increased in 7-year-olds. We found age risk factors. Sensitization to Japanese cedar pollinosis appeared in 7-year-old, with symptoms of pollinosis developing in 8-year-olds. We compared the percentage of positive rate of antibodies of Japanese cedar pollen with percentage of Dermatophagoides farinae (Der f) from the student's blood samples. Children having Der f antibodies showing higher positive rate of Japanese cedar pollen antibodies than children who do not have Der f antibodies. Sensitization to Japanese cedar pollen is dependent on Der f. We paid attention to resident environments. Children having Japanese cedar pollen antibodies were higher in children living in the urban than in rural. The percentage of onset of symptoms was higher in apartment buildings than in detached houses. In conclusion, sensitization to Japanese cedar pollen occurs mostly at age 6 - 7, is influenced by type of dwelling (apartment or house), (specially by Der f) and it's onset is affected by urban or rural.

Adolescent↗