DNA clamp

A DNA clamp, also known as a sliding 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.

Structure

The DNA clamp fold is an α+β protein that assembles into a multimeric structure that completely encircles the DNA double helix as the polymerase adds nucleotides to the growing strand. The DNA clamp assembles on the DNA at the replication fork and "slides" along the DNA with the advancing polymerase, aided by a layer of water molecules in the central pore of the clamp between the DNA and the protein surface. Because of the toroidal shape of the assembled multimer, the clamp cannot dissociate from the template strand without also dissociating into monomers.

Nipple clamp

A nipple clamp is a clamp that can be applied to the nipples of any type of body. It is a sex toy which can be attached to the nipples to create pain by restricting blood flow from erect nipples by applying pressure to them. Some people derive erotic pleasure from seeing nipple clamps applied. They are used in some BDSM activities, such as tit torture. The use of nipple clamps is often portrayed in the media as deviant or kinky sexual behavior.

The main types of nipple clamp are the clover clamp, tweezer clamp, and clothes-pin style, though any device that applies direct pressure can be used. For self-use, successful application requires the user to find a personal balance between the amount of pain and pleasure by fine tuning the degree of pressure exerted by the clamp. The clamps are typically used in pairs and connected by a chain. Weights may be hung from the clamps to increase the pressure on the nipples, and to discourage the clamped person from moving suddenly (for example, jumping when spanked or caned), since this would make the weights swing and increase the pain.

Clamp (manga artists)

Clamp (クランプ, Kuranpu), is an all-female Japanese manga artist group that formed in the mid-1980s. It consists of leader Nanase Ohkawa (大川 七瀬, Ōkawa Nanase), and three artists whose roles shift for each series: Mokona (もこな, Mokona), Tsubaki Nekoi (猫井 椿, Nekoi Tsubaki), and Satsuki Igarashi (いがらし 寒月, Igarashi Satsuki). Almost 100 million Clamp tankōbon copies have been sold worldwide as of October 2007.

Beginning as an eleven-member dōjinshi circle in the mid-1980s, they began creating original work in 1987. By the time they debuted with RG Veda in 1989, the group was reduced to seven members. In 1993, three more members left, leaving the four members who are currently still part of the group. In 2006, the members decided to change their names; Ohkawa later changed her name back from Ageha Ohkawa to Nanase Ohkawa, while the other three members retained their new names.

History

Before their debut (1980s–1989)

Clamper (electronics)

A clamper is an electronic circuit that fixes either the positive or the negative peak excursions of a signal to a defined value by shifting its DC value. The clamper does not restrict the peak-to-peak excursion of the signal, it moves the whole signal up or down so as to place the peaks at the reference level. A diode clamp (a simple, common type) consists of a diode, which conducts electric current in only one direction and prevents the signal exceeding the reference value; and a capacitor which provides a DC offset from the stored charge. The capacitor forms a time constant with the resistor load which determines the range of frequencies over which the clamper will be effective.

General function

A clamping circuit (also known as a clamper) will bind the upper or lower extreme of a waveform to a fixed DC voltage level. These circuits are also known as DC voltage restorers. Clampers can be constructed in both positive and negative polarities. When unbiased, clamping circuits will fix the voltage lower limit (or upper limit, in the case of negative clampers) to 0 Volts. These circuits clamp a peak of a waveform to a specific DC level compared with a capacitively coupled signal which swings about its average DC level.

DNA

Deoxyribonucleic acid (ⁱ/diˈɒksiˌraɪboʊnjʊˌkliːɪk, -ˌkleɪɪk/;DNA) is a molecule that carries most of the genetic instructions used in the development, functioning and reproduction of all known living organisms and many viruses. DNA is a nucleic acid; alongside proteins and carbohydrates, nucleic acids compose the three major macromolecules essential for all known forms of life. Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are known as polynucleotides since they are composed of simpler units called nucleotides. Each nucleotide is composed of a nitrogen-containing nucleobase—either cytosine (C), guanine (G), adenine (A), or thymine (T)—as well as a monosaccharide sugar called deoxyribose and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. According to base pairing rules (A with T, and C with G), hydrogen bonds bind the nitrogenous bases of the two separate polynucleotide strands to make double-stranded DNA. The total amount of related DNA base pairs on Earth is estimated at 5.0 x 10³⁷, and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).

List of minor planets: 55001–56000

DNA²

DNA² (Japanese: D・N・A² ～何処かで失くしたあいつのアイツ～, Hepburn: Dī En Ei Tsū: Dokoka de Nakushita Aitsu no Aitsu) is a science fiction manga series written and illustrated by Masakazu Katsura. It was serialized across Shueisha's Weekly Shōnen Jump magazine between 1993 and 1994, spanning a total of five tankōbon volumes.

DNA² was adapted into a 12-episode anime television series which ran on Nippon Television from October 7, 1994 to December 23, 1994. This was followed by a three-episode anime original video animation (OVA) in 1995. Produced by Madhouse and Studio Deen, the anime series was directed by Jun'ichi Sakata, whereas the character designer and animation director for the series was Kumiko Takahashi. DNA² has been broadcast in Japan by Animax, which has also aired the series across its respective networks worldwide, including its English-language networks in Southeast Asia and South Asia. All 15 episodes were licensed in North America by Central Park Media until their closing in 2009. The five volumes and box set are out-of-print. Discotek Media has since re-licensed the series for a DVD release in 2014.