In biology and genetics, the germline is the population of a multicellular organism's cells that pass on their genetic material to the progeny (offspring). In other words, they are the cells that form the egg, sperm and the fertilised egg. They are usually differentiated to perform this function and segregated in a specific place away from other bodily cells.
A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata. It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords. The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals. They are the only chordates that have lost their myomeric segmentation, with the possible exception of the 'seriation of the gill slits'. However, doliolids still display segmentation of the muscle bands.
Self-pollination is a form of pollination in which pollen from the same plant arrives at the stigma of a flower or at the ovule. There are two types of self-pollination: in autogamy, pollen is transferred to the stigma of the same flower; in geitonogamy, pollen is transferred from the anther of one flower to the stigma of another flower on the same flowering plant, or from microsporangium to ovule within a single (monoecious) gymnosperm. Some plants have mechanisms that ensure autogamy, such as flowers that do not open (cleistogamy), or stamens that move to come into contact with the stigma. The term selfing that is often used as a synonym, is not limited to self-pollination, but also applies to other type of self-fertilization.
Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" made of a polysaccharide.
Ciona intestinalis is an ascidian, a tunicate with very soft tunic. Its Latin name literally means "pillar of intestines", referring to the fact that its body is a soft, translucent column-like structure, resembling a mass of intestines sprouting from a rock. It is a globally distributed cosmopolitan species. Since Linnaeus described the species, Ciona intestinalis has been used as a model invertebrate chordate in developmental biology and genomics. Studies conducted between 2005 and 2010 have shown that there are at least two, possibly four, sister species. More recently it has been shown that one of these species has already been described as Ciona robusta. By anthropogenic means, the species has invaded various parts of the world and is known as an invasive species.
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.
Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas, and pansies, this behavior is most widespread in the grass family. However, the largest genus of cleistogamous plants is Viola.
Botryllus schlosseri is a colonial ascidian tunicate. It is commonly known as the star tunicate, but it also has several other common names, including star ascidian and golden star tunicate. Colonies grow on slow-moving, submerged objects, plants, and animals in nearshore saltwater environments.
Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate between hermaphroditism and dioecy.
Sperm chemotaxis is a form of sperm guidance, in which sperm cells (spermatozoa) follow a concentration gradient of a chemoattractant secreted from the oocyte and thereby reach the oocyte.
Albert Erives is a developmental geneticist who studies transcriptional enhancers underlying animal development and diseases of development (cancers). Erives also proposed the pacRNA model for the dual origin of the genetic code and universal homochirality. He is known for work at the intersection of genetics, evolution, developmental biology, and gene regulation. He has worked at the California Institute of Technology, University of California, Berkeley, and Dartmouth College, and is an associate professor at the University of Iowa.
Ascidiella aspersa, the European sea squirt, is a species of solitary sea squirts native to the northeastern Atlantic, from the Mediterranean Sea to Norway. They possess oval bodies up to 50 to 130 mm in length. Their branchial siphons are conical and positioned at the top of the body. They possess six to eight lobes. The atrial siphons are located at the upper third of the side of the body and possess six lobes. The body is covered by a firm transparent test that is greyish to brown in color. The test often snag detritus that remain loosely attached to the animal. When expanded, at most 40 tentacles can be observed on the inside surface of the branchial wall. Both the openings of the branchial and atrial siphons possess lighter colored ridges on their rims. They may also be frilled at times. A. aspersa are attached to the substrates by the left side of their bodies. They can be found in dense groups of unfused individuals on hard surfaces like rocks. at depths of up to 90 m (300 ft).
Didemnum molle is a species of colonial tunicate in the family Didemnidae. It is commonly known as the tall urn ascidian, the green barrel sea squirt or the green reef sea-squirt. It is native to the Red Sea and the tropical waters of the Indo-Pacific region.
Didemnum vexillum is a species of colonial tunicate in the family Didemnidae. It is commonly called sea vomit, marine vomit, pancake batter tunicate, or carpet sea squirt. It is thought to be native to Japan, but it has been reported as an invasive species in a number of places in Europe, North America and New Zealand. It is sometimes given the nickname "D. vex" because of the vexing way in which it dominates marine ecosystems when introduced into new locations, however the species epithet vexillum actually derives from the Latin word for flag, and the species was so named because of the way colonies' long tendrils appear to wave in the water like a flag.
Ciona savignyi is a marine animal sometimes known as the Pacific transparent sea squirt or solitary sea squirt. It is a species of tunicates in the family Cionidae. It is found in shallow waters around Japan and has spread to the west coast of North America where it is regarded as an invasive species.
Cell lineage denotes the developmental history of a tissue or organ from the fertilized embryo. This is based on the tracking of an organism's cellular ancestry due to the cell divisions and relocation as time progresses, this starts with the originator cells and finishing with a mature cell that can no longer divide.
Molgula citrina is a species of solitary tunicate in the family Molgulidae. It is found on both sides of the northern Atlantic Ocean and in the Arctic Ocean. In 2008 it was found in Kachemak Bay in Alaska, the first time it had been detected in the Pacific Ocean.
The ascidian mitochondrial code is a genetic code found in the mitochondria of Ascidia.
Autogamy, or self-fertilization, refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species of protists have also been observed using autogamy as a means of reproduction. Flowering plants engage in autogamy regularly, while the protists that engage in autogamy only do so in stressful environments.
Ciona robusta is a species of marine invertebrate in the genus Ciona of the family Cionidae. The holotype was collected on the northeastern coast of Honshu Island, Japan. Populations of Ciona intestinalis known as Ciona intestinalis type A found in the Mediterranean Sea, the Pacific Ocean, east coast of North America, and the Atlantic coasts of South Africa have been shown to be Ciona robusta.
