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Gametogenesis: The process of germ cell development from the primordial GERM CELLS to the mature haploid GAMETES: ova in the female (OOGENESIS) or sperm in the male (SPERMATOGENESIS).Gametogenesis, Plant: The process of germ cell development in plants, from the primordial PLANT GERM CELLS to the mature haploid PLANT GAMETES.Plants, Genetically Modified: PLANTS, or their progeny, whose GENOME has been altered by GENETIC ENGINEERING.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Genes, Plant: The functional hereditary units of PLANTS.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Plant Shoots: New immature growth of a plant including stem, leaves, tips of branches, and SEEDLINGS.Spermatogenesis: The process of germ cell development in the male from the primordial germ cells, through SPERMATOGONIA; SPERMATOCYTES; SPERMATIDS; to the mature haploid SPERMATOZOA.Germ Cells: The reproductive cells in multicellular organisms at various stages during GAMETOGENESIS.DNA, Plant: Deoxyribonucleic acid that makes up the genetic material of plants.Oogenesis: The process of germ cell development in the female from the primordial germ cells through OOGONIA to the mature haploid ova (OVUM).Plants, Medicinal: Plants whose roots, leaves, seeds, bark, or other constituent parts possess therapeutic, tonic, purgative, curative or other pharmacologic attributes, when administered to man or animals.Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Plant Development: Processes orchestrated or driven by a plethora of genes, plant hormones, and inherent biological timing mechanisms facilitated by secondary molecules, which result in the systematic transformation of plants and plant parts, from one stage of maturity to another.Meiosis: A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.Plants, Toxic: Plants or plant parts which are harmful to man or other animals.Plant Cells: Basic functional unit of plants.Testis: The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.Arabidopsis Proteins: Proteins that originate from plants species belonging to the genus ARABIDOPSIS. The most intensely studied species of Arabidopsis, Arabidopsis thaliana, is commonly used in laboratory experiments.Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Pollen: The fertilizing element of plants that contains the male GAMETOPHYTES.Genome, Plant: The genetic complement of a plant (PLANTS) as represented in its DNA.Reproduction: The total process by which organisms produce offspring. (Stedman, 25th ed)Genomic Imprinting: The variable phenotypic expression of a GENE depending on whether it is of paternal or maternal origin, which is a function of the DNA METHYLATION pattern. Imprinted regions are observed to be more methylated and less transcriptionally active. (Segen, Dictionary of Modern Medicine, 1992)Plants, Edible: An organism of the vegetable kingdom suitable by nature for use as a food, especially by human beings. Not all parts of any given plant are edible but all parts of edible plants have been known to figure as raw or cooked food: leaves, roots, tubers, stems, seeds, buds, fruits, and flowers. The most commonly edible parts of plants are FRUIT, usually sweet, fleshy, and succulent. Most edible plants are commonly cultivated for their nutritional value and are referred to as VEGETABLES.Plant Structures: The parts of plants, including SEEDS.Spermatocytes: Male germ cells derived from SPERMATOGONIA. The euploid primary spermatocytes undergo MEIOSIS and give rise to the haploid secondary spermatocytes which in turn give rise to SPERMATIDS.Plant Growth Regulators: Any of the hormones produced naturally in plants and active in controlling growth and other functions. There are three primary classes: auxins, cytokinins, and gibberellins.Ovary: The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.XanthurenatesGonads: The gamete-producing glands, OVARY or TESTIS.Seeds: The encapsulated embryos of flowering plants. They are used as is or for animal feed because of the high content of concentrated nutrients like starches, proteins, and fats. Rapeseed, cottonseed, and sunflower seed are also produced for the oils (fats) they yield.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Ovule: The element in plants that contains the female GAMETOPHYTES.Helleborus: A plant genus of the family RANUNCULACEAE. Members contain hellebrin (BUFANOLIDES). The extract is the basis of Boicil preparation used to treat rheumatism.Spores, Fungal: Reproductive bodies produced by fungi.Vitellogenesis: The active production and accumulation of VITELLINS (egg yolk proteins) in the non-mammalian OOCYTES from circulating precursors, VITELLOGENINS. Vitellogenesis usually begins after the first MEIOSIS and is regulated by estrogenic hormones.Plant Immunity: The inherent or induced capacity of plants to withstand or ward off biological attack by pathogens.Tobacco: A plant genus of the family SOLANACEAE. Members contain NICOTINE and other biologically active chemicals; its dried leaves are used for SMOKING.Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Meiotic Prophase I: The prophase of the first division of MEIOSIS (in which homologous CHROMOSOME SEGREGATION occurs). It is divided into five stages: leptonema, zygonema, PACHYNEMA, diplonema, and diakinesis.Gene Expression Regulation, Developmental: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.Flowers: The reproductive organs of plants.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).Plant Epidermis: A thin layer of cells forming the outer integument of seed plants and ferns. (Random House Unabridged Dictionary, 2d ed)Fertility: The capacity to conceive or to induce conception. It may refer to either the male or female.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Plant Stomata: Closable openings in the epidermis of plants on the underside of leaves. They allow the exchange of gases between the internal tissues of the plant and the outside atmosphere.Hermaphroditic Organisms: Animals and plants which have, as their normal mode of reproduction, both male and female sex organs in the same individual.Angiosperms: Members of the group of vascular plants which bear flowers. They are differentiated from GYMNOSPERMS by their production of seeds within a closed chamber (OVARY, PLANT). The Angiosperms division is composed of two classes, the monocotyledons (Liliopsida) and dicotyledons (Magnoliopsida). Angiosperms represent approximately 80% of all known living plants.Embryonic Development: Morphological and physiological development of EMBRYOS.snRNP Core Proteins: The protein components that constitute the common core of small nuclear ribonucleoprotein particles. These proteins are commonly referred as Sm nuclear antigens due to their antigenic nature.DNA Methylation: Addition of methyl groups to DNA. DNA methyltransferases (DNA methylases) perform this reaction using S-ADENOSYLMETHIONINE as the methyl group donor.Plant Poisoning: Poisoning by the ingestion of plants or its leaves, berries, roots or stalks. The manifestations in both humans and animals vary in severity from mild to life threatening. In animals, especially domestic animals, it is usually the result of ingesting moldy or fermented forage.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Plant Transpiration: The loss of water vapor by plants to the atmosphere. It occurs mainly from the leaves through pores (stomata) whose primary function is gas exchange. The water is replaced by a continuous column of water moving upwards from the roots within the xylem vessels. (Concise Dictionary of Biology, 1990)Spermatogonia: Euploid male germ cells of an early stage of SPERMATOGENESIS, derived from prespermatogonia. With the onset of puberty, spermatogonia at the basement membrane of the seminiferous tubule proliferate by mitotic then meiotic divisions and give rise to the haploid SPERMATOCYTES.Disorders of Sex Development: In gonochoristic organisms, congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Effects from exposure to abnormal levels of GONADAL HORMONES in the maternal environment, or disruption of the function of those hormones by ENDOCRINE DISRUPTORS are included.Lycopersicon esculentum: A plant species of the family SOLANACEAE, native of South America, widely cultivated for their edible, fleshy, usually red fruit.Haploidy: The chromosomal constitution of cells, in which each type of CHROMOSOME is represented once. Symbol: N.Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Chlamydomonas reinhardtii: A species of GREEN ALGAE. Delicate, hairlike appendages arise from the flagellar surface in these organisms.Cyclin A1: A cyclin A subtype primarily found in male GERM CELLS. It may play a role in the passage of SPERMATOCYTES into meiosis I.Plant Tumors: A localized proliferation of plant tissue forming a swelling or outgrowth, commonly with a characteristic shape and unlike any organ of the normal plant. Plant tumors or galls usually form in response to the action of a pathogen or a pest. (Holliday, P., A Dictionary of Plant Pathology, 1989, p330)Chromosomes, Plant: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.DNA (Cytosine-5-)-Methyltransferase: An enzyme that catalyzes the transfer of a methyl group from S-ADENOSYLMETHIONINE to the 5-position of CYTOSINE residues in DNA.Plant Components, Aerial: The above-ground plant without the roots.Proto-Oncogene Proteins c-kit: A protein-tyrosine kinase receptor that is specific for STEM CELL FACTOR. This interaction is crucial for the development of hematopoietic, gonadal, and pigment stem cells. Genetic mutations that disrupt the expression of PROTO-ONCOGENE PROTEINS C-KIT are associated with PIEBALDISM, while overexpression or constitutive activation of the c-kit protein-tyrosine kinase is associated with tumorigenesis.Life Cycle Stages: The continuous sequence of changes undergone by living organisms during the post-embryonic developmental process, such as metamorphosis in insects and amphibians. This includes the developmental stages of apicomplexans such as the malarial parasite, PLASMODIUM FALCIPARUM.Chlamydomonas: A genus GREEN ALGAE in the order VOLVOCIDA. It consists of solitary biflagellated organisms common in fresh water and damp soil.Infertility, Male: The inability of the male to effect FERTILIZATION of an OVUM after a specified period of unprotected intercourse. Male sterility is permanent infertility.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.RNA-Binding Proteins: Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA.Zygote: The fertilized OVUM resulting from the fusion of a male and a female gamete.Infertility: Inability to reproduce after a specified period of unprotected intercourse. Reproductive sterility is permanent infertility.Sex Differentiation: The process in developing sex- or gender-specific tissue, organ, or function after SEX DETERMINATION PROCESSES have set the sex of the GONADS. Major areas of sex differentiation occur in the reproductive tract (GENITALIA) and the brain.Plant Preparations: Material prepared from plants.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.