OCLC Online Computer Library Center, Incorporated d/b/a OCLC is an American nonprofit cooperative organization "dedicated to the public purposes of furthering access to the world's information and reducing information costs". It was founded in 1967 as the Ohio College Library Center. OCLC and its member libraries cooperatively produce and maintain WorldCat, the largest online public access catalog in the world. OCLC is funded by the fees that libraries have to pay for its services. OCLC maintains the Dewey Decimal Classification system. OCLC began in 1967, as the Ohio College Library Center, through a collaboration of university presidents, vice presidents, library directors who wanted to create a cooperative computerized network for libraries in the state of Ohio; the group first met on July 5, 1967 on the campus of the Ohio State University to sign the articles of incorporation for the nonprofit organization, hired Frederick G. Kilgour, a former Yale University medical school librarian, to design the shared cataloging system.
Kilgour wished to merge the latest information storage and retrieval system of the time, the computer, with the oldest, the library. The plan was to merge the catalogs of Ohio libraries electronically through a computer network and database to streamline operations, control costs, increase efficiency in library management, bringing libraries together to cooperatively keep track of the world's information in order to best serve researchers and scholars; the first library to do online cataloging through OCLC was the Alden Library at Ohio University on August 26, 1971. This was the first online cataloging by any library worldwide. Membership in OCLC is based on use of services and contribution of data. Between 1967 and 1977, OCLC membership was limited to institutions in Ohio, but in 1978, a new governance structure was established that allowed institutions from other states to join. In 2002, the governance structure was again modified to accommodate participation from outside the United States.
As OCLC expanded services in the United States outside Ohio, it relied on establishing strategic partnerships with "networks", organizations that provided training and marketing services. By 2008, there were 15 independent United States regional service providers. OCLC networks played a key role in OCLC governance, with networks electing delegates to serve on the OCLC Members Council. During 2008, OCLC commissioned two studies to look at distribution channels. In early 2009, OCLC negotiated new contracts with the former networks and opened a centralized support center. OCLC provides bibliographic and full-text information to anyone. OCLC and its member libraries cooperatively produce and maintain WorldCat—the OCLC Online Union Catalog, the largest online public access catalog in the world. WorldCat has holding records from private libraries worldwide; the Open WorldCat program, launched in late 2003, exposed a subset of WorldCat records to Web users via popular Internet search and bookselling sites.
In October 2005, the OCLC technical staff began a wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. WikiD was phased out; the Online Computer Library Center acquired the trademark and copyrights associated with the Dewey Decimal Classification System when it bought Forest Press in 1988. A browser for books with their Dewey Decimal Classifications was available until July 2013; until August 2009, when it was sold to Backstage Library Works, OCLC owned a preservation microfilm and digitization operation called the OCLC Preservation Service Center, with its principal office in Bethlehem, Pennsylvania. The reference management service QuestionPoint provides libraries with tools to communicate with users; this around-the-clock reference service is provided by a cooperative of participating global libraries. Starting in 1971, OCLC produced catalog cards for members alongside its shared online catalog. OCLC commercially sells software, such as CONTENTdm for managing digital collections.
It offers the bibliographic discovery system WorldCat Discovery, which allows for library patrons to use a single search interface to access an institution's catalog, database subscriptions and more. OCLC has been conducting research for the library community for more than 30 years. In accordance with its mission, OCLC makes its research outcomes known through various publications; these publications, including journal articles, reports and presentations, are available through the organization's website. OCLC Publications – Research articles from various journals including Code4Lib Journal, OCLC Research, Reference & User Services Quarterly, College & Research Libraries News, Art Libraries Journal, National Education Association Newsletter; the most recent publications are displayed first, all archived resources, starting in 1970, are available. Membership Reports – A number of significant reports on topics ranging from virtual reference in libraries to perceptions about library funding. Newsletters – Current and archived newsletters for the library and archive community.
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Molecular phylogenetics is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominately in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to determine the processes by which diversity among species has been achieved; the result of a molecular phylogenetic analysis is expressed in a phylogenetic tree. Molecular phylogenetics is one aspect of molecular systematics, a broader term that includes the use of molecular data in taxonomy and biogeography. Molecular phylogenetics and molecular evolution correlate. Molecular evolution is the process of selective changes at a molecular level throughout various branches in the tree of life. Molecular phylogenetics makes inferences of the evolutionary relationships that arise due to molecular evolution and results in the construction of a phylogenetic tree; the figure displayed on the right depicts the phylogenetic tree of life as one of the first detailed trees, according to information known in the 1870s by Haeckel.
The theoretical frameworks for molecular systematics were laid in the 1960s in the works of Emile Zuckerkandl, Emanuel Margoliash, Linus Pauling, Walter M. Fitch. Applications of molecular systematics were pioneered by Charles G. Sibley, Herbert C. Dessauer, Morris Goodman, followed by Allan C. Wilson, Robert K. Selander, John C. Avise. Work with protein electrophoresis began around 1956. Although the results were not quantitative and did not improve on morphological classification, they provided tantalizing hints that long-held notions of the classifications of birds, for example, needed substantial revision. In the period of 1974–1986, DNA-DNA hybridization was the dominant technique used to measure genetic difference. Early attempts at molecular systematics were termed as chemotaxonomy and made use of proteins, enzymes and other molecules that were separated and characterized using techniques such as chromatography; these have been replaced in recent times by DNA sequencing, which produces the exact sequences of nucleotides or bases in either DNA or RNA segments extracted using different techniques.
In general, these are considered superior for evolutionary studies, since the actions of evolution are reflected in the genetic sequences. At present, it is still a expensive process to sequence the entire DNA of an organism. However, it is quite feasible to determine the sequence of a defined area of a particular chromosome. Typical molecular systematic analyses require the sequencing of around 1000 base pairs. At any location within such a sequence, the bases found in a given position may vary between organisms; the particular sequence found in a given organism is referred to as its haplotype. In principle, since there are four base types, with 1000 base pairs, we could have 41000 distinct haplotypes. However, for organisms within a particular species or in a group of related species, it has been found empirically that only a minority of sites show any variation at all, most of the variations that are found are correlated, so that the number of distinct haplotypes that are found is small. In a molecular systematic analysis, the haplotypes are determined for a defined area of genetic material.
Haplotypes of individuals of related, yet different, taxa are determined. Haplotypes from a smaller number of individuals from a different taxon are determined: these are referred to as an outgroup; the base sequences for the haplotypes are compared. In the simplest case, the difference between two haplotypes is assessed by counting the number of locations where they have different bases: this is referred to as the number of substitutions; the difference between organisms is re-expressed as a percentage divergence, by dividing the number of substitutions by the number of base pairs analysed: the hope is that this measure will be independent of the location and length of the section of DNA, sequenced. An older and superseded approach was to determine the divergences between the genotypes of individuals by DNA-DNA hybridization; the advantage claimed for using hybridization rather than gene sequencing was that it was based on the entire genotype, rather than on particular sections of DNA. Modern sequence comparison techniques overcome this objection by the use of multiple sequences.
Once the divergences between all pairs of samples have been determined, the resulting triangular matrix of differences is submitted to some form of statistical cluster analysis, the resulting dendrogram is examined in order to see whether the samples cluster in the way that would be expected from current ideas about the taxonomy of the group. Any group of haplotypes that are all more similar to one another than any of them is to any other haplotype may be said to constitute a clade, which may be visually represented as the figure displayed on the right demonstrates. Statistical techniques such as bootstrapping and jackknifing help in providing reliability estimates for the positions of haplotypes within the evolutionary trees; every living organism contains deoxyribonucleic acid, ribonucleic acid, proteins. In general related organisms have a high degree of similarity in the molecular structure of these substances, while the molecules of organisms distantly related s
A cilium is an organelle found on eukaryotic cells and are slender protuberances that project from the much larger cell body. There are two types of cilia: motile cilia and non-motile, or primary, which serve as sensory organelles. In eukaryotes, motile cilia and flagella together make up a group of organelles known as undulipodia. Eukaryotic cilia are structurally identical to eukaryotic flagella, although distinctions are sometimes made according to function and/or length. Biologists have various ideas about. Cilia can be divided into motile forms. In animals, primary cilia are found on nearly every cell. In comparison to motile cilia, non-motile cilia occur one per cell. In addition, examples of specialized primary cilia can be found in human sensory organs such as the eye and the nose: The outer segment of the rod photoreceptor cell in the human eye is connected to its cell body with a specialized non-motile cilium; the dendritic knob of the olfactory neuron, where the odorant receptors are located contains non-motile cilia.
Although the primary cilium was discovered in 1898, it was ignored for a century. Only has great progress been made in understanding the function of the primary cilium; until the 1990s, the prevailing view of the primary cilium was that it was a vestigial organelle without important function. Recent findings regarding its physiological roles in chemical sensation, signal transduction, control of cell growth, have led scientists to acknowledge its importance in cell function, with the discovery of its role in diseases not recognized to involve the dysgenesis and dysfunction of cilia, such as polycystic kidney disease, congenital heart disease, an emerging group of genetic ciliopathies, it is known that the cilium must be disassembled before mitosis can occur. However, the mechanisms that control this process are still unknown; the primary cilium is now known to play an important role in the function of many human organs. The current scientific understanding of primary cilia views them as "sensory cellular antennae that coordinate a large number of cellular signaling pathways, sometimes coupling the signaling to ciliary motility or alternatively to cell division and differentiation.".
The primary non-motile cilia is divided into subdomains. The entire structure is enclosed by a plasma membrane continuous with the plasma membrane of the cell; the basal body, where the cilia originates, is located within the ciliary pocket. The cilium membrane and the basal body microtubules are connected by transition fibers. Vesicles carrying molecules for the cilia dock at the transition fibers; the transition fibers form a transition zone where entry and exit of molecules is regulated to and from the cilia. Molecules can move to the tip of the cilia with the aid of anterograde IFT particles and the kinesin-2 motor. Molecules can use retrograde IFT particles and the cytoplasmic dynein motor to move toward the basal body; some of the signaling with these cilia occur through ligand binding such as Hedgehog signaling. Other forms of signaling include G-coupled receptors including the somatostatin receptor 3 in neuronal cells. Larger eukaryotes, such as mammals, have motile cilia as well. Motile cilia are present on a cell's surface in large numbers and beat in coordinated waves.
In humans, for example, motile cilia are found in the lining of the trachea, where they sweep mucus and dirt out of the lungs. In female mammals, the beating of cilia in the Fallopian tubes moves the ovum from the ovary to the uterus; the functioning of motile cilia is dependent on the maintenance of optimal levels of fluid bathing the cilia. Epithelial sodium channels ENaC that are expressed along the entire length of cilia serve as sensors that regulate fluid level surrounding the cilia. Ciliates are microscopic organisms that possess motile cilia and use them for either locomotion or to move liquid over their surface. Inside cilia and flagella is a microtubule-based cytoskeleton called the axoneme; the axoneme of primary cilia has a ring of nine outer microtubule doublets, the axoneme of a motile cilium has two central microtubule singlets in addition to the nine outer doublets. The axonemal cytoskeleton acts as a scaffolding for various protein complexes and provides binding sites for molecular motor proteins such as kinesin II, that help carry proteins up and down the microtubules.
On the outside of cilia is a membrane like the plasma membrane, but compositionally distinct due to a blocking ring around the base, distinct in its population of receptors and other integral proteins. The ciliary rootlet is a cytoskeleton-like structure that originates from the basal body at the proximal end of a cilium, it extends proximally toward the cell nucleus. Rootlets are 80-100 nm in diameter and contain cross striae distributed at regular intervals of 55-70 nm. According to the Gene Ontology, the following proteins localize to the ciliary rootlet: amyloid precursor protein, rootletin and presenilins. Though they have been given different names, motile cilia and flagella have nearly identical structures and have the same purpose: motion; the movement of the appendage can be described as a wave. The wave tends to originate from the cilium base and can be described in terms of frequency and wave length; the beating motion is creat
Chlorella is a genus of single-celled green algae belonging to the division Chlorophyta. It is spherical in shape, about 2 to 10 μm in diameter, is without flagella. Chlorella contains the green photosynthetic pigments chlorophyll-a and -b in its chloroplast. Through photosynthesis, it multiplies requiring only carbon dioxide, sunlight, a small amount of minerals to reproduce; the name Chlorella is taken from the Greek χλώρος, meaning green, the Latin diminutive suffix ella, meaning small. German biochemist and cell physiologist Otto Heinrich Warburg, awarded with the Nobel Prize in Physiology or Medicine in 1931 for his research on cell respiration studied photosynthesis in Chlorella. In 1961, Melvin Calvin of the University of California received the Nobel Prize in Chemistry for his research on the pathways of carbon dioxide assimilation in plants using Chlorella. Many people believe Chlorella can serve as a potential source of food and energy because its photosynthetic efficiency can, in theory, reach 8%, which exceeds that of other efficient crops such as sugar cane.
Chlorella is a potential food source. Mass-production methods are now being used to cultivate it in large man-made circular ponds, it is used as a'superfood' and can be found as an ingredient in certain liquid-based cocktails. When first harvested, Chlorella was suggested as an inexpensive protein supplement to the human diet. Advocates sometimes focus on other supposed health benefits of the algae, such as claims of weight control, cancer prevention, immune system support. According to the American Cancer Society, "available scientific studies do not support its effectiveness for preventing or treating cancer or any other disease in humans". Under certain growing conditions, Chlorella yields oils that are high in polyunsaturated fats—Chlorella minutissima has yielded eicosapentaenoic acid at 39.9% of total lipids. Following global fears of an uncontrollable human population boom during the late 1940s and the early 1950s, Chlorella was seen as a new and promising primary food source and as a possible solution to the then-current world hunger crisis.
Many people during this time thought hunger would be an overwhelming problem and saw Chlorella as a way to end this crisis by providing large amounts of high-quality food for a low cost. Many institutions began to research the algae, including the Carnegie Institution, the Rockefeller Foundation, the NIH, UC Berkeley, the Atomic Energy Commission, Stanford University. Following World War II, many Europeans were starving, many Malthusians attributed this not only to the war, but to the inability of the world to produce enough food to support the increasing population. According to a 1946 FAO report, the world would need to produce 25 to 35% more food in 1960 than in 1939 to keep up with the increasing population, while health improvements would require a 90 to 100% increase; because meat was costly and energy-intensive to produce, protein shortages were an issue. Increasing cultivated area alone would go only so far in providing adequate nutrition to the population; the USDA calculated that, to feed the U.
S. population by 1975, it would have to add 200 million acres of land, but only 45 million were available. One way to combat national food shortages was to increase the land available for farmers, yet the American frontier and farm land had long since been extinguished in trade for expansion and urban life. Hopes rested on new agricultural techniques and technologies; because of these circumstances, an alternative solution was needed. To cope with the upcoming postwar population boom in the United States and elsewhere, researchers decided to tap into the unexploited sea resources. Initial testing by the Stanford Research Institute showed Chlorella could convert 20% of solar energy into a plant that, when dried, contains 50% protein. In addition, Chlorella contains vitamins; the plant's photosynthetic efficiency allows it to yield more protein per unit area than any plant—one scientist predicted 10,000 tons of protein a year could be produced with just 20 workers staffing a 1000-acre Chlorella farm.
The pilot research performed at Stanford and elsewhere led to immense press from journalists and newspapers, yet did not lead to large-scale algae production. Chlorella seemed like a viable option because of the technological advances in agriculture at the time and the widespread acclaim it got from experts and scientists who studied it. Algae researchers had hoped to add a neutralized Chlorella powder to conventional food products, as a way to fortify them with vitamins and minerals; when the preliminary laboratory results were published, the scientific community at first backed the possibilities of Chlorella. Science News Letter praised the optimistic results in an article entitled "Algae to Feed the Starving". John Burlew, the editor of the Carnegie Institution of Washington book Algal Culture-from Laboratory to Pilot Plant, stated, "the algae culture may fill a real need," which Science News Letter turned into "future populations of the world will be kept from starving by the production of improved or educated algae related to the green scum on ponds."
The cover of the magazine featured Arthur D. Little's Cambridge laboratory, a supposed future food factory. A few years the magazine published an article entitled "Tomorrow's Dinner", which stated, "There is no doubt in the mind of scientists that the farms of the future will be factories." Science Digest reported, "common pond scum would soon bec
Lorenz Oken was a German naturalist, botanist and ornithologist. Oken was born Lorenz Okenfuss in Bohlsbach, Ortenau and studied natural history and medicine at the universities of Freiburg and Würzburg, he went on to the University of Göttingen, where he became a Privatdozent, shortened his name to Oken. As Lorenz Oken, he published a small work entitled Grundriss der Naturphilosophie, der Theorie der Sinne, mit der darauf gegründeten Classification der Thiere; this was the first of a series of works which established him as a leader of the movement of "Naturphilosophie" in Germany. In it he extended to physical science the philosophical principles which Immanuel Kant had applied to epistemology and morality. Oken had been preceded in this by Gottlieb Fichte, acknowledging that Kant had discovered the materials for a universal science, declared that all, needed was a systematic coordination of these materials. Fichte undertook this task in his "Doctrine of Science", whose aim was to construct all knowledge by a priori means.
This attempt, sketched out by Fichte, was further elaborated by the philosopher Friedrich Schelling. Oken built on Schelling's work. Oken produced the seven-volume series Allgemeine Naturgeschichte für alle Stände, with engravings by Johann Susemihl, published in Stuttgart by Hoffman between 1839 and 1841. In the Grundriss der Naturphilosophie of 1802 Oken sketched the outlines of the scheme he afterwards devoted himself to perfecting; the position advanced in that work, to which he continued to adhere, is that "the animal classes are nothing else than a representation of the sense-organs, that they must be arranged in accordance with them." Oken contended that there are only five animal classes: Dermatozoa, or invertebrates Glossozoa, or fish, those animals in which a true tongue makes, for the first time, its appearance Rhinozoa, or reptiles, in which the nose opens for the first time into the mouth and inhales air Otozoa, or birds, in which the ear for the first time opens externally Ophthalmozoa, or mammals, in which all the organs of sense are present and complete, the eyes being movable and covered with lids.
In 1805 Oken made a further advance in the application of the a priori principle in a book on generation, in which he maintained that "all organic beings originate from and consist of vesicles or cells. These vesicles, when singly detached and regarded in their original process of production, are the infusorial mass or protoplasma whence all larger organisms fashion themselves or are evolved, their production is therefore nothing else than a regular agglomeration of Infusoria—not, of course, of species elaborated or perfect, but of mucous vesicles or points in general, which first form themselves by their union or combination into particular species."A year after the production of this treatise, Oken developed his system one stage further, in a volume published in 1806, written with the assistance of Dietrich von Kieser, entitled Beiträge zur vergleichenden Zoologie, und Physiologie, he demonstrated that the intestines originate from the umbilical vesicle, that this corresponds to the vitellus or yolk-bag.
Caspar Wolff had claimed to demonstrate this fact in the chick, but he did not see its application as evidence of a general law. Oken showed the importance of the discovery as an illustration of his system. In the same work Oken described and recalled attention to the corpora Wolffiana, or "primordial kidneys." The reputation of the young Privatdozent of Göttingen had reached the ear of Johann von Goethe, in 1807 Oken was invited to fill the office of Extraordinary Professor of the Medical Sciences at the University of Jena. He selected for the subject of his inaugural discourse his ideas on the "Signification of the Bones of the Skull," based on a discovery of the previous year; this lecture was delivered in the presence of Goethe, as privy councillor and rector of the university, was published in the same year, with the title, Ueber die Bedeutung der Schädelknochen. With regard to the origin of the idea, Oken narrates in his Isis that, walking one autumn day in 1806 in the Harz forest, he stumbled on the blanched skull of a deer, picked up the dislocated bones, contemplated them for a while, when it occurred to him, "It is a vertebral column!"
At a meeting of the German naturalists held at Jena some years afterwards, Professor Kieser gave an account of Oken's discovery in the presence of the grand duke, printed in the Tageblatt, or "proceedings,” of that meeting. The professor stated that Oken told him of his discovery when journeying in 1806 to the island of Wangerooge. On their return to Göttingen, Oken explained his ideas by reference to the skull of a turtle in Kieser's collection, which he disarticulated for that purpose. Kieser displayed the skull, its bones marked in Oken's handwriting. Oken's lectures at Jena were wide-ranging, were regarded at the time; the subjects included natural philosophy, general natural history, comparative anatomy, the physiology of man, of animals and of plants. The spirit with which he grappled with the vast scope of science is characteristically illustrated in his essay Ueber das Universum als Fortsetzung des Sinnensystems. In this work he lays it down that "organism is none other than a combination of all the universe's activities within a single individual body."
This doctrine led him to the conviction t
A contractile vacuole is a sub-cellular structure involved in osmoregulation. It is found predominantly in unicellular algae, it was known as pulsatile or pulsating vacuole The contractile vacuole is a specialized type of vacuole that regulates the quantity of water inside a cell. In freshwater environments, the concentration of solutes is hypotonic, higher inside than outside the cell. Under these conditions, water osmosis causes water to accumulate in the cell from the external environment; the contractile vacuole acts as part of a protective mechanism that prevents the cell from absorbing too much water and lysing through excessive internal pressure. The contractile vacuole, as its name suggests, expels water out of the cell by contracting; the growth and contraction of the contractile vacuole are periodical. One cycle takes several seconds, depending on the environment's osmolarity; the stage in which water flows into the CV is called diastole. The contraction of the contractile vacuole and the expulsion of water out of the cell is called systole.
Water always flows first from outside the cell into the cytoplasm, is only moved from the cytoplasm into the contractile vacuole for expulsion. Species that possess a contractile vacuole always use the organelle at hypertonic environments, since the cell tends to adjust its cytoplasm to become more hyperosmotic than the environment; the amount of water expelled from the cell and the rate of contraction are related to the osmolarity of the environment. In hyperosmotic environments, less water will be expelled and the contraction cycle will be longer; the best understood contractile vacuoles belong to the protists Paramecium, Amoeba and Trypanosoma, to a lesser extent the green alga Chlamydomonas. Not all species that possess a contractile vacuole are freshwater organisms; the contractile vacuole is predominant in species that do not have a cell wall, but there are exceptions which do possess a cell wall. Through Evolution, the contractile vacuole has been lost in multicellular organisms, but it still exists in the unicellular stage of several multicellular fungi, as well as in several types of cells in sponges.
The number of contractile vacuoles per cell varies, depending on the species. Amoeba have one, Dictyostelium discoideum, Paramecium aurelia and Chlamydomonas reinhardtii have two, giant amoeba, such as Chaos carolinensis, have many; the number of contractile vacuoles in each species is constant and is therefore used for species characterization in systematics. The contractile vacuole has several structures attached to it in most cells, such as membrane folds, water tracts and small vesicles; these structures have been termed the spongiome. The spongiome serves several functions in water transport into the contractile vacuole and in localization and docking of the contractile vacuole within the cell. Paramecium and Amoeba possess large contractile vacuoles, which are comfortable to isolate and assay; the smallest known contractile vacuoles belong with a diameter of 1.5 µm. In Paramecium, which has one of the most complex contractile vacuoles, the vacuole is surrounded by several canals, which absorb water by osmosis from the cytoplasm.
After the canals fill with water, the water is pumped into the vacuole. When the vacuole is full, it expels the water through a pore in the cytoplasm which can be opened and closed. Other protists, such as Amoeba, have CVs that move to the surface of the cell when full and undergo exocytosis. In Amoeba contractile vacuoles collect excretory waste, such as ammonia, from the intracellular fluid by both diffusion and active transport; the way in which water enters the CV had been a mystery for many years, but several discoveries since the 1990s have improved understanding of this issue. Water could theoretically cross the CV membrane by osmosis, but only if the inside of the CV is hyperosmotic to the cytoplasm; the discovery of proton pumps in the CV membrane and the direct measurement of ion concentrations inside the CV using microelectrodes led to the following model: the pumping of protons either into or out of the CV causes different ions to enter the CV. For example, some proton pumps work as cation exchangers, whereby a proton is pumped out of the CV and a cation is pumped at the same time into the CV.
In other cases, protons pumped into the CV drag anions with them, to balance the pH. This ion flux into the CV causes an increase in CV osmolarity and as a result water enters the CV by osmosis. Water has been shown in at least some species to enter the CV through aquaporins. Acidocalcisomes have been implied to work alongside the contractile vacuole in responding to osmotic stress, they were detected in the vicinity of the vacuole in Trypanosoma cruzi and were shown to fuse with the vacuole when the cells were exposed to osmotic stress. The acidocalcisomes empty their ion contents into the contractile vacuole, thereby increasing the vacuole's osmolarity; the CV indeed does not exist in higher organisms, but some of its unique characteristics are used by the former in their own osmoregulatory mechanisms. Research on the CV can therefore help us understand. Many issues regarding the CV remain, unsolved: Contraction. I
Stentor coeruleus is a protist in the family Stentoridae, characterized by being a large ciliate that measures 0.5 to 2 millimetres when extended. Stentor coeruleus appears as a large trumpet, it contains a macronucleus that looks like a string of beads that are contained within a ciliate, blue to blue-green in color. Being that it has many myonemes, it has the ability to contract into a ball, it has the ability to swim while both extended or contracted. Eating is accomplished using cilia; the genome sequence revealed two remarkable aspects. The genetic code is the "universal" code, somewhat unusual for ciliates; the introns are unusually small, only 15 or 16 nucleotides long. Stentor coeruleus are capable of sexual reproduction, or conjugation, but reproduce asexually by binary fission