Clamps are the main attachment structure of the Polyopisthocotylean monogeneans.
These ectoparasitic worms have a variable number of clamps on their haptor (the posterior attachment organ); each clamp is attached to the host fish, generally to its gill. Clamps include sclerotised elements, called the sclerites, and muscles. The structure of clamps varies according to the groups within the Polyopisthocotylean monogeneans; microcotylids have relatively simple clamps, whereas gastrocotylids have more complex clamps.
Polyopisthocotylea is a subclass of parasitic flatworms in the class Monogenea.
Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female reproductive structures. Monogeneans have a series of hooks which are used to attach onto fish, and as a result, could lead to infections.
The haptor is the attachment organ of the monogeneans, a group of parasitic Platyhelminthes. The haptor is sometimes called opisthaptor to emphasize that it is located in the posterior part of the body, and to differentiate it from the prohaptor, a structure including glands located at the anterior part of the body. According to Yamaguti (1963), the chief adhesive organ of the monogeneans, the haptor, is posterior, more or less discoid, muscular, may be divided into alveoli or loculi, is usually provided with anchors, has nearly always marginal larval hooklets, or is in a reduced form with anchors. The haptor may consist of symmetrical or asymmetrical, sessile or pedunculate, muscular suckers or clamps with or without supporting sclerites; accessory adhesive organs may be present in form of armed plaques, lappets or appendices.
A sclerite is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly to the hardened parts of arthropod exoskeletons and the internal spicules of invertebrates such as certain sponges and soft corals. In paleontology, a scleritome is the complete set of sclerites of an organism, often all that is known from fossil invertebrates.
In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell.
DNA polymerase is an enzyme that synthesizes DNA molecules from deoxyribonucleotides, the building blocks of DNA. These enzymes are essential for DNA replication and usually work in pairs to create two identical DNA strands from a single original DNA molecule. During this process, DNA polymerase "reads" the existing DNA strands to create two new strands that match the existing ones.
Vestigiality is the retention during the process of evolution of genetically determined structures or attributes that have lost some or all of their ancestral function in a given species. Assessment of the vestigiality must generally rely on comparison with homologous features in related species. The emergence of vestigiality occurs by normal evolutionary processes, typically by loss of function of a feature that is no longer subject to positive selection pressures when it loses its value in a changing environment. The feature may be selected against more urgently when its function becomes definitively harmful, but if the lack of the feature provides no advantage, and its presence provides no disadvantage, the feature may not be phased out by natural selection and persist across species.
A DNA clamp, also known as a sliding clamp or β-clamp, is a protein fold that serves as a processivity-promoting factor in DNA replication. As a critical component of the DNA polymerase III holoenzyme, the clamp protein binds DNA polymerase and prevents this enzyme from dissociating from the template DNA strand. The clamp-polymerase protein–protein interactions are stronger and more specific than the direct interactions between the polymerase and the template DNA strand; because one of the rate-limiting steps in the DNA synthesis reaction is the association of the polymerase with the DNA template, the presence of the sliding clamp dramatically increases the number of nucleotides that the polymerase can add to the growing strand per association event. The presence of the DNA clamp can increase the rate of DNA synthesis up to 1,000-fold compared with a nonprocessive polymerase.
Cichlidogyrus is a genus of monopisthocotylean monogeneans in the family Ancyrocephalidae. The type-species of the genus is Cichlidogyrus arthracanthusPaperna, 1960, by original designation. All the species of the genus are parasites on the gills of fish, namely African Cichlidae, Nandidae and Cyprinodontidae.
Protomicrocotylidae is a family of monogenean parasites in the order Mazocraeidea.
Lethacotyle is a genus of polyopisthocotylean monogeneans, included in the family Protomicrocotylidae.
The genus includes only two species: Lethacotyle fijiensisManter & Price, 1953 , the type-species of the genus, and Lethacotyle veraJustine, Rahmouni, Gey, Schoelinck, & Hoberg, 2013 . Both species are parasitic on the gills of jacks in the Pacific Ocean. They are known only from three localities: off Fiji, Andaman Islands, and New Caledonia.
The genus Lethacotyle is special in that its members have no clamps on their posterior attachment organ or haptor, in contrast to most polyopisthocotylean Monogenean which have clamps. This is reflected in the etymology of the name, which, according to Manter & Price is "from letha = forgetting, and cotyle = cup, and refers to the absence of clamps".
Lethacotyle fijiensis is a species of monogeneans of the family Protomicrocotylidae.
Lethacotyle vera is a species of monogenean of the family Protomicrocotylidae.
Pseudorhabdosynochus is a genus of monopisthocotylean monogeneans, included in the family Diplectanidae.The type-species of the genus is Pseudorhabdosynochus epinepheli .
Lee Hong Susan Lim, more commonly known as Susan Lim, was a Malaysian parasitologist who specialised on the Monogenea, a class of parasitic flatworms which are important ectoparasites of fishes. She was the first and only Malaysian commissioner elected to the International Commission on Zoological Nomenclature. Her research was mainly in the fields of taxonomy and faunistics, although in later years, she became involved in a wide range of parasitological disciplines.
Pseudorhabdosynochus firmicoleatus is a diplectanid monogenean parasite on the gills of the Yellowedge grouper, Epinephelus flavolimbatus and the Snowy grouper, Epinephelus niveatus. It as been described by Kritsky, Bakenhaster and Adams in 2015.
Hexabothriidae is a family of monogenean parasites. The family name was proposed by Emmett W. Price in 1942. The family includes 14-16 genera according to authors and about 60 species; all are parasitic on the gills of chondrichthyan fishes.
Microcotyle longirostri is a species of monogenean, parasitic on the gills of a marine fish. It belongs to the family Microcotylidae.
Pseudaxine trachuri is a species of monogenean, parasitic on the gills of a marine fish. It belongs to the family Gastrocotylidae.
Sibitrema is a genus which belongs to the phylum Platyhelminthes and class Monogenea; the only species included in this genus is parasite of fish.