Paramecium: A genus of ciliate protozoa that is often large enough to be seen by the naked eye. Paramecia are commonly used in genetic, cytological, and other research.Paramecium tetraurelia: A species of ciliate protozoa. It is used in biomedical research.Paramecium caudatum: The most widely distributed species of PARAMECIUM. It is elongated and possesses a bluntly pointed posterior.Paramecium aurelia: A species of ciliated PARAMECIUM possessing two micronuclei.Cilia: Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)Chlorella: Nonmotile unicellular green algae potentially valuable as a source of high-grade protein and B-complex vitamins.Genes, Protozoan: The functional hereditary units of protozoa.Macronucleus: The larger of two types of nuclei in ciliate protozoans. It is the transcriptionally active nucleus of the vegetative cells as distinguished from the smaller transcriptionally inert GERMLINE MICRONUCLEUS.Micronucleus, Germline: The smaller, reproductive, transcriptionally inert nucleus in the cells of ciliate protozoans, as distinguished from the larger, vegetative, transcriptionally active MACRONUCLEUS. Micronuclei participate in MEIOSIS and autogamy during GENETIC CONJUGATION.DNA, Protozoan: Deoxyribonucleic acid that makes up the genetic material of protozoa.Phycodnaviridae: A family of DNA plant viruses that infect eukaryotic algae.Genome, Protozoan: The complete genetic complement contained in a set of CHROMOSOMES in a protozoan.Protozoan Proteins: Proteins found in any species of protozoan.Ciliophora: A phylum of EUKARYOTES characterized by the presence of cilia at some time during the life cycle. It comprises three classes: KINETOFRAGMINOPHOREA; OLIGOHYMENOPHOREA; and POLYMENOPHOREA.Exocytosis: Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.Holosporaceae: A family of bacteria comprised of endosymbionts of protozoa.Organoids: An organization of cells into an organ-like structure. Organoids can be generated in culture. They are also found in certain neoplasms.After-Hours Care: Medical care provided after the regular practice schedule of the physicians. Usually it is designed to deliver 24-hour-a-day and 365-day-a-year patient care coverage for emergencies, triage, pediatric care, or hospice care.Science: The study of natural phenomena by observation, measurement, and experimentation.Play and Playthings: Spontaneous or voluntary recreational activities pursued for enjoyment and accessories or equipment used in the activities; includes games, toys, etc.Food: Any substances taken in by the body that provide nourishment.Hair: A filament-like structure consisting of a shaft which projects to the surface of the SKIN from a root which is softer than the shaft and lodges in the cavity of a HAIR FOLLICLE. It is found on most surfaces of the body.Mouth: The oval-shaped oral cavity located at the apex of the digestive tract and consisting of two parts: the vestibule and the oral cavity proper.Amoeba: A genus of ameboid protozoa. Characteristics include a vesicular nucleus and the formation of several lodopodia, one of which is dominant at a given time. Reproduction occurs asexually by binary fission.Video Games: A form of interactive entertainment in which the player controls electronically generated images that appear on a video display screen. This includes video games played in the home on special machines or home computers, and those played in arcades.Game Theory: Theoretical construct used in applied mathematics to analyze certain situations in which there is an interplay between parties that may have similar, opposed, or mixed interests. In a typical game, decision-making "players," who each have their own goals, try to gain advantage over the other parties by anticipating each other's decisions; the game is finally resolved as a consequence of the players' decisions.Cercaria: The free-swimming larval forms of parasites found in an intermediate host.Microscopy: The use of instrumentation and techniques for visualizing material and details that cannot be seen by the unaided eye. It is usually done by enlarging images, transmitted by light or electron beams, with optical or magnetic lenses that magnify the entire image field. With scanning microscopy, images are generated by collecting output from the specimen in a point-by-point fashion, on a magnified scale, as it is scanned by a narrow beam of light or electrons, a laser, a conductive probe, or a topographical probe.Gene Expression Profiling: The determination of the pattern of genes expressed at the level of GENETIC TRANSCRIPTION, under specific circumstances or in a specific cell.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.Betaproteobacteria: A class in the phylum PROTEOBACTERIA comprised of chemoheterotrophs and chemoautotrophs which derive nutrients from decomposition of organic material.Ponds: Inland bodies of standing FRESHWATER usually smaller than LAKES. They can be man-made or natural but there is no universal agreement as to their exact size. Some consider a pond to be a small body of water that is shallow enough for sunlight to reach the bottom.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Scyphozoa: The class of true jellyfish, in the phylum CNIDARIA. They are mostly free-swimming marine organisms that go through five stages in their life cycle and exhibit two body forms: polyp and medusa.Beta Particles: High energy POSITRONS or ELECTRONS ejected from a disintegrating atomic nucleus.Genetics: The branch of science concerned with the means and consequences of transmission and generation of the components of biological inheritance. (Stedman, 26th ed)Strontium Radioisotopes: Unstable isotopes of strontium that decay or disintegrate spontaneously emitting radiation. Sr 80-83, 85, and 89-95 are radioactive strontium isotopes.PubMed: A bibliographic database that includes MEDLINE as its primary subset. It is produced by the National Center for Biotechnology Information (NCBI), part of the NATIONAL LIBRARY OF MEDICINE. PubMed, which is searchable through NLM's Web site, also includes access to additional citations to selected life sciences journals not in MEDLINE, and links to other resources such as the full-text of articles at participating publishers' Web sites, NCBI's molecular biology databases, and PubMed Central.Oceania: The islands of the central and South Pacific, including Micronesia, Melanesia, Polynesia, and traditionally Australasia. (Random House Dictionary, 2d ed)Gene Duplication: Processes occurring in various organisms by which new genes are copied. Gene duplication may result in a MULTIGENE FAMILY; supergenes or PSEUDOGENES.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Vacuoles: Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion.Curriculum: A course of study offered by an educational institution.Ciliophora Infections: Infections with protozoa of the phylum CILIOPHORA.Tetrahymena thermophila: A species of ciliate protozoa used in genetic and cytological research.Oligohymenophorea: A class of ciliate protozoa. Characteristics include the presence of a well developed oral apparatus and oral cilia being clearly distinct from somatic cilia.Sharks: A group of elongate elasmobranchs. Sharks are mostly marine fish, with certain species large and voracious.Lions: Large, chiefly nocturnal mammals of the cat family FELIDAE, species Panthera leo. They are found in Africa and southern Asia.Tigers: The species Panthera tigris, a large feline inhabiting Asia. Several subspecies exist including the Siberian tiger and Sumatran tiger.Annelida: A phylum of metazoan invertebrates comprising the segmented worms, and including marine annelids (POLYCHAETA), freshwater annelids, earthworms (OLIGOCHAETA), and LEECHES. Only the leeches are of medical interest. (Dorland, 27th ed)