Black people is a skin group-based classification used for specific people with a mid to dark brown complexion. Not all black people have dark skin, it is used for the people of Sub-Saharan African descent and the indigenous peoples of Oceania, Southeast Asia and the Indian subcontinent. Different societies apply different criteria regarding, classified "black", these social constructs have changed over time. In a number of countries, societal variables affect classification as much as skin color, the social criteria for "blackness" vary. In the United Kingdom, "black" was equivalent with "person of color", a general term for non-European peoples. In other regions such as Australasia, settlers applied the term "black" or it was used by local populations with different histories and ancestral backgrounds. For many other individuals and countries, "black" is perceived as a derogatory, reductive or otherwise unrepresentative label, as a result is neither used nor defined in African cultures with little to no colonial history.
Some have pointed out that labeling people groups "black" is erroneous as the people described as "black" have a brown skin color. The Romans interacted with and conquered parts of Mauretania, an early state that covered modern Morocco, western Algeria, the Spanish cities Ceuta and Melilla during classical period; the people of the region were noted in classical literature as Mauri, subsequently rendered as Moors in English. Numerous communities of dark-skinned peoples are present in North Africa, some dating from prehistoric communities. Others descend from immigrants via the historical trans-Saharan trade or, after the Arab invasions of North Africa in the 7th century, from slaves from the Arab slave trade in North Africa. In the 18th century, the Moroccan Sultan Moulay Ismail "the Warrior King" raised a corps of 150,000 black soldiers, called his Black Guard. According to Carlos Moore, resident scholar at Brazil's University of the State of Bahia, in the 21st century Afro-multiracials in the Arab world, including Arabs in North Africa, self-identify in ways that resemble multi-racials in Latin America.
He claims that darker toned Arabs, much like darker toned Latin Americans, consider themselves white because they have some distant white ancestry. Egyptian President Anwar Sadat had a mother, a dark-skinned Nubian Sudanese woman and a father, a lighter-skinned Egyptian. In response to an advertisement for an acting position, as a young man he said, "I am not white but I am not black either. My blackness is tending to reddish". Due to the patriarchal nature of Arab society, Arab men, including during the slave trade in North Africa, enslaved more African women than men, they used more enslaved African female in domestic agriculture than males. The men interpreted the Quran to permit sexual relations between a male master and his enslaved females outside of marriage, leading to many mixed-race children; when an enslaved woman became pregnant with her Arab master's child, she was considered as umm walad or "mother of a child", a status that granted her privileged rights. The child was given rights of inheritance to the father's property, so mixed-race children could share in any wealth of the father.
Because the society was patrilineal, the children took their fathers' social status at birth and were born free. Some succeeded their fathers as rulers, such as Sultan Ahmad al-Mansur, who ruled Morocco from 1578 to 1608, he was not technically considered as a mixed-race child of a slave. In early 1991, non-Arabs of the Zaghawa people of Sudan attested that they were victims of an intensifying Arab apartheid campaign, segregating Arabs and non-Arabs. Sudanese Arabs, who controlled the government, were referred to as practicing apartheid against Sudan's non-Arab citizens; the government was accused of "deftly manipulat Arab solidarity" to carry out policies of apartheid and ethnic cleansing. American University economist George Ayittey accused the Arab government of Sudan of practicing acts of racism against black citizens. According to Ayittey, "In Sudan... the Arabs monopolized power and excluded blacks – Arab apartheid." Many African commentators joined Ayittey in accusing Sudan of practising Arab apartheid.
In the Sahara, the native Tuareg Berber populations kept "negro" slaves. Most of these captives were of Nilotic extraction, were either purchased by the Tuareg nobles from slave markets in the Western Sudan or taken during raids, their origin is denoted via the Ahaggar Berber word Ibenheren, which alludes to slaves that only speak a Nilo-Saharan language. These slaves were sometimes known by the borrowed Songhay term Bella; the Sahrawi indigenous peoples of the Western Sahara observed a class system consisting of high castes and low castes. Outside of these traditional tribal boundaries were "Negro" slaves, who were drawn from the surrounding areas. In parts of the Horn of Africa, the local Afroasiatic speaking populations have long adhered to a construct similar to that of the Sahara and Maghreb. In Ethiopia and Somalia, the slave classes consisted of individuals of Nilotic and Bantu origin who were collectively known as Shanqella and Adone; these captives and others of analogous morphology were distinguished as tsalim barya in contrast with the Afroasiatic-speaking nob
In pharmacology, the term mechanism of action refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action includes mention of the specific molecular targets to which the drug binds, such as an enzyme or receptor. Receptor sites have specific affinities for drugs based on the chemical structure of the drug, as well as the specific action that occurs there. Drugs that do not bind to receptors produce their corresponding therapeutic effect by interacting with chemical or physical properties in the body. Common examples of drugs that work in this way are laxatives. In contrast, a mode of action describes functional or anatomical changes, at the cellular level, resulting from the exposure of a living organism to a substance. Elucidating the mechanism of action of novel drugs and medications is important for several reasons: In the case of anti-infective drug development, the information permits anticipation of problems relating to clinical safety.
Drugs disrupting the cytoplasmic membrane or electron transport chain, for example, are more to cause toxicity problems than those targeting components of the cell wall or 70S ribosome, structures which are absent in human cells. By knowing the interaction between a certain site of a drug and a receptor, other drugs can be formulated in a way that replicates this interaction, thus producing the same therapeutic effects. Indeed, this method is used to create new drugs, it can help identify which patients are most to respond to treatment. Because the breast cancer medication trastuzumab is known to target protein HER2, for example, tumors can be screened for the presence of this molecule to determine whether or not the patient will benefit from trastuzumab therapy, it can enable better dosing because the drug's effects on the target pathway can be monitored in the patient. Statin dosage, for example, is determined by measuring the patient's blood cholesterol levels, it allows drugs to be combined in such a way that the likelihood of drug resistance emerging is reduced.
By knowing what cellular structure an anti-infective or anticancer drug acts upon, it is possible to administer a cocktail that inhibits multiple targets thereby reducing the risk that a single mutation in microbial or tumor DNA will lead to drug resistance and treatment failure. It may allow other indications for the drug to be identified. Discovery that sildenafil inhibits phosphodiesterase-5 proteins, for example, enabled this drug to be repurposed for pulmonary arterial hypertension treatment, since PDE-5 is expressed in pulmonary hypertensive lungs. Bioactive compounds induce phenotypic changes in target cells, changes that are observable by microscopy, which can give insight into the mechanism of action of the compound. With antibacterial agents, the conversion of target cells to spheroplasts can be an indication that peptidoglycan synthesis is being inhibited, filamentation of target cells can be an indication that PBP3, FtsZ or DNA synthesis is being inhibited. Other antibacterial agent-induced changes include ovoid cell formation, pseudomulticellular forms, localized swelling, bulge formation and peptidoglycan thickening.
In the case of anticancer agents, bleb formation can be an indication that the compound is disrupting the plasma membrane. A current limitation of this approach is the time required to manually generate and interpret data, but advances in automated microscopy and image analysis software may help resolve this. Direct biochemical methods include methods in which a protein or a small molecule, such as a drug candidate, is labeled and is traced throughout the body; this proves to be the most direct approach to find target protein that will bind to small targets of interest, such as a basic representation of a drug outline, in order to identify the pharmacophore of the drug. Due to the physical interactions between the labeled molecule and a protein, biochemical methods can be used to determine the toxicity and the mechanism of action of the drug. Computation inference methods are used to predict protein targets for small molecule drugs based on computer based pattern recognition. However, this method could be used for finding new targets for existing or newly developed drugs.
By identifying the pharmacophore of the drug molecule, the profiling method of pattern recognition can be carried out where a new target is identified. This provides an insight at a possible mechanism of action, as it is known what certain functional components of the drug are responsible for interacting with a certain area on a protein, leading to a therapeutic effect. Omics based methods use omics technologies, such as reverse genetics and genomics and proteomics, to identify the potential targets of the compound of interest. Reverse genetics and genomics approaches, for instance, uses genetic perturbation in combination with the compound to identify genes whose knockdown or knockout abolishes the pharmacological effect of the compound. On the other hand and proteomics profiles of the compound can be used to compare with profiles of compounds with known targets. Thanks to computation inference, it is possible to make hypotheses about the mechanism of action of the compound, which can subsequently be tested.
There are many drugs. One example is aspirin; the mechanism of action of aspirin involves irreversible inhibition of the enzyme cyclooxygenase. This mechanism of action is specific to aspirin, is not constant fo
Epioblasma triquetra, common name the snuffbox mussel, is a species of freshwater mussel, a mollusk in the family Unionidae. It is native to eastern North America, where it is a listed as an endangered species in both Canada and the United States; this species lives the Great Lakes system and Mississippi River system. Its natural habitat is riffles and shoals of rocky rivers, the shores of lakes with wave activity; this species is declining throughout its range due to habitat destruction, siltation and competition with invasive species. Despite this, it remains the most widespread and abundant member of the genus Epioblasma, of which the other members are now either extinct or imperiled. All Unionidae are known to use the gills, fins, or skin of a host fish for nutrients during the larval glochidia stage. In 2004, it was discovered that female Epioblasma triquetra mussels lure the unsuspecting fish towards them quickly clamp onto the head of the host fish and pump the glochidia larvae into their gills.
The primary confirmed host fish for Epioblasma triquetra was found to be the common logperch, due to it being able to survive this violent encounter