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Clone (cell Biology)
A clone is a group of ''identical'' cells that share a ''common ancestry'', meaning they are derived from the same cell. Clonality implies the state of a cell or a substance being derived from one source or the other. Thus there are terms like ''polyclonal''—derived from many clones; ''oligoclonal''—derived from a few clones; and ''monoclonal''—derived from one clone. These terms are most commonly used in context of antibodies or immunocytes. Contexts This concept of clone assumes importance as all the cells that form a clone share common ancestry, which has a very significant consequence: shared genotype. # One of the most prominent usage is in describing a clone of B cells. The B cells in the body have two important phenotypes (functional forms)—the antibody secreting, terminally differentiated (that is, they cannot divide further) plasma cells, and the memory and the naive cells—both of which retain their proliferative potential. # Another important area where o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clonal Expansion And Monoclonal Versus Polyclonal Proliferation
Clonal may refer to: Biology *Clonal interference, a phenomenon that occurs when two (or more) beneficial mutations arise independently in different individuals in a genetically homogeneous population of an asexually reproducing organism *Aggregating anemone, also called clonal anemone *Vegetative cloning, a form of asexual reproduction in plants *Clonal reproduction Immunology *Clonal deletion, a process by which B cells and T cells are deactivated before act significantly upon specific antigens *Clonal selection theory, a model for how the immune system responds to infection *Clonal anergy, a lack of reaction by the body's defense mechanisms to foreign substance See also *Clone (other) *Clonalis House *Clone (genetics) *Cloning {{dab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paramecium
''Paramecium'' ( , , plural "paramecia" only when used as a Common name, vernacular name) is a genus of eukaryotic, unicellular ciliates, widespread in freshwater, brackish, and Ocean, marine environments. Paramecia are often abundant in stagnant basins and ponds. Because some species are readily cultivated and easily induced to sexual conjugation, conjugate and divide, they have been widely used in classrooms and laboratories to study biological processes. ''Paramecium'' species are commonly studied as model organisms of the ciliate group and have been characterized as the "laboratory rat, white rats" of the phylum Ciliophora. Historical background ''Paramecium'' were among the first ciliates to be observed by microscopy, microscopists, in the late 17th century. They were most likely known to the Dutch pioneer of protozoology, Antonie van Leeuwenhoek, and were clearly described by his contemporary Christiaan Huygens in a letter from 1678. The earliest known illustration of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumour Heterogeneity
Tumour heterogeneity describes the observation that different tumour cells can show distinct morphological and phenotypic profiles, including cellular morphology, gene expression, metabolism, motility, proliferation, and metastatic potential. This phenomenon occurs both between tumours (inter-tumour heterogeneity) and within tumours (intra-tumour heterogeneity). A minimal level of intra-tumour heterogeneity is a simple consequence of the imperfection of DNA replication: whenever a cell (normal or cancerous) divides, a few mutations are acquired—leading to a diverse population of cancer cells. The heterogeneity of cancer cells introduces significant challenges in designing effective treatment strategies. However, research into understanding and characterizing heterogeneity can allow for a better understanding of the causes and progression of disease. In turn, this has the potential to guide the creation of more refined treatment strategies that incorporate knowledge of heteroge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyclonal Response
Polyclonal B cell response is a natural mode of immune response exhibited by the adaptive immune system of mammals. It ensures that a single antigen is recognized and attacked through its overlapping parts, called epitopes, by multiple Clone (B-cell biology), clones of B cell. In the course of normal immune response, parts of pathogens (e.g. bacteria) are recognized by the immune system as foreign (non-self), and eliminated or effectively neutralized to reduce their potential damage. Such a recognizable substance is called an antigen. The immune system may respond in multiple ways to an antigen; a key feature of this response is the production of antibodies by B cells (or B lymphocytes) involving an arm of the immune system known as humoral immunity. The antibodies are soluble and do not require direct cell-to-cell contact between the pathogen and the B-cell to function. Antigens can be large and complex substances, and any single antibody can only bind to a small, specific area ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyclonal Antibodies
Polyclonal antibodies (pAbs) are antibodies that are secreted by different B cell lineages within the body (whereas monoclonal antibodies come from a single cell lineage). They are a collection of immunoglobulin molecules that react against a specific antigen, each identifying a different epitope. Production The general procedure to produce polyclonal antibodies is as follows: # Antigen preparation # Adjuvant selection and preparation # Animal selection # Injection process # Blood serum extraction An antigen/adjuvant conjugate is injected into an animal of choice to initiate an amplified immune response. After a series of injections over a specific length of time, the animal is expected to have created antibodies against the conjugate. Blood is then extracted from the animal and then purified to obtain the antibody of interest. Inoculation is performed on a suitable mammal, such as a mouse, rabbit or goat. Larger mammals are often preferred as the amount of serum that can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Animals That Have Been Cloned
Banteng *A Javan banteng calf was cloned from frozen cells using a cow as a surrogate, delivered via c-section on April 1, 2003, then hand raised at the San Diego Wild Animal Parks Infant Isolation Unit. It died due to an injury when it was less than seven years old, about half the normal life of a banteng. Black-footed ferret Elizabeth Ann, a black-footed ferret female, was born on December 10, 2020, at the Fish and Wildlife Service's Black-footed Ferret Conservation Center in Colorado. She is a clone of a female named Willa, who died in the mid-1980s and left no living descendants. Brown rat *Ralph (male, 2003) Camel Injaz, a cloned female dromedary camel, was born in 2009 at the Camel Reproduction Center in Dubai, United Arab Emirates after an "uncomplicated" gestation of 378 days. Carp Embryologist Tong Dizhou successfully inserted the DNA from a male Asian carp into the egg of a female Asian carp to create the first fish clone in 1963. Cat *In 2001, scientists at Tex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloning
Cloning is the process of producing individual organisms with identical genomes, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction; this reproduction of an organism by itself without a mate is known as parthenogenesis. In the field of biotechnology, cloning is the process of creating cloned organisms of Cell (biology), cells and of DNA fragments. The artificial cloning of organisms, sometimes known as reproductive cloning, is often accomplished via somatic-cell nuclear transfer (SCNT), a cloning method in which a viable embryo is created from a somatic cell and an egg cell. In 1996, Dolly (sheep), Dolly the sheep achieved notoriety for being the first mammal cloned from a somatic cell. Another example of artificial cloning is molecular cloning, a technique in molecular biology in which a single living cell is used to clone a large population of cells that contain identical DNA molecules. In bioethics, there are a vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clone (B-cell Biology)
The process of immunological B-cell maturation involves transformation from an undifferentiated B cell to one that secretes antibodies with particular specificity. This differentiation and activation of the B cell occurs most rapidly after exposure to antigen by antigen-presenting cells in the reticuloendothelial system, and under modulation by T cells, and is closely intertwined with affinity maturation. B cells that respond most avidly to antigen are preferentially allowed to proliferate and mature, a process known as clonal selection. In lymphocytic neoplastic diseases such as multiple myeloma and lymphoma, but also other illnesses, there can be a massive expansion of a single B-cell clone, detectable by measuring the excessively-produced antibodies, measured in a serum protein electrophoresis test or peripheral blood flow cytometry. Such an expansion is said to be "monoclonal", and monoclonal antibodies produced by such a group of B cells can cause illnesses such as am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Damage Theory Of Aging
The DNA damage theory of aging proposes that aging is a consequence of unrepaired accumulation of DNA damage (naturally occurring), naturally occurring DNA damage. Damage in this context is a DNA alteration that has an abnormal structure. Although both mitochondrion, mitochondrial and Cell nucleus, nuclear DNA damage can contribute to aging, nuclear DNA is the main subject of this analysis. Nuclear DNA damage can contribute to aging either indirectly (by increasing apoptosis or Hayflick limit, cellular senescence) or directly (by increasing cell dysfunction). Several review articles have shown that deficient DNA repair, allowing greater accumulation of DNA damage, causes premature aging; and that increased DNA repair facilitates greater longevity, e.g. Mouse models of nucleotide-excision–repair syndromes reveal a striking correlation between the degree to which specific DNA repair pathways are compromised and the severity of accelerated aging, strongly suggesting a causal relation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Damage (naturally Occurring)
Natural DNA damage is an alteration in the chemical structure of DNA, such as a break in a strand of DNA, a nucleobase missing from the backbone of DNA, or a chemically changed base such as 8-OHdG. DNA damage can occur naturally or via environmental factors, but is distinctly different from mutation, although both are types of error in DNA. DNA damage is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of base pairs. DNA damages cause changes in the structure of the genetic material and prevents the replication mechanism from functioning and performing properly. The DNA damage response (DDR) is a complex signal transduction pathway which recognizes when DNA is damaged and initiates the cellular response to the damage. DNA damage and mutation have different biological consequences. While most DNA damages can undergo DNA repair, such repair is not 100% efficient. Un-repaired DNA damages accumulate in non-replicating cells, such as cells in the brai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterial Conjugation
Bacterial conjugation is the transfer of genetic material between Bacteria, bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a pilus. It is a parasexual cycle, parasexual mode of reproduction in bacteria. It is a mechanism of horizontal gene transfer as are Transformation (genetics), transformation and Transduction (genetics), transduction although these two other mechanisms do not involve cell-to-cell contact. Classical ''E. coli'' bacterial conjugation is often regarded as the bacterial equivalent of sexual reproduction or mating, since it involves the exchange of genetic material. However, it is not sexual reproduction, since no exchange of gamete occurs, and indeed no biogenesis, generation of a new organism: instead, an existing organism is transformed. During classical ''E. coli'' conjugation, the ''donor'' cell provides a conjugative or mobilizable genetic element that is most often a plasmid or trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autogamy
Autogamy or self-fertilization refers to the Cell fusion, fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a Reproduction, 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. Occurrence Protists ''Paramecium aurelia'' ''Paramecium aurelia'' is the most commonly studied protozoan for autogamy. Similar to other unicellular organisms, ''Paramecium aurelia'' typically reproduce asexually via Fission (biology), binary fission or sexually via cross-fertilization. However, studies have shown that when put under nutritional stress, ''Paramecium aurelia'' will undergo meiosis and subsequent fusion of Gamete, gametic-like nuclei. This process, defined as hemixis, a chromosomal rearrangement pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
