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Microbial DNA Barcoding
Microbial DNA barcoding is the use of DNA metabarcoding to characterize a mixture of microorganisms. DNA metabarcoding is a method of DNA barcoding that uses universal genetic markers to identify DNA of a mixture of organisms. History Using metabarcoding to assess microbial communities has a long history. Back in 1972, Carl Woese, Mitchell Sogin and Stephen Sogin first tried to detect several families within bacteria using the 5S rRNA gene. Only a few years later, a new tree of life with three domains was proposed by again Woese and colleagues, who were the first to use the small subunit of the ribosomal RNA (SSU rRNA) gene to distinguish between bacteria, archaea and eukaryotes. Out of this approach, the SSU rRNA gene made its way to be the most frequently used genetic marker for both prokaryotes (16S rRNA) and eukaryotes ( 18S rRNA). The tedious process of cloning those DNA fragments for sequencing got fastened up by the steady improvement of sequencing technologies. With ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloning
Cloning is the process of producing individual organisms with identical or virtually identical DNA, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction. In the field of biotechnology, cloning is the process of creating cloned organisms (copies) of Cell (biology), cells and of DNA fragments (molecular cloning). Etymology Coined by Herbert J. Webber, the term clone derives from the Ancient Greek word (), ''twig'', which is the process whereby a new plant is created from a twig. In botany, the term ''lusus'' was used. In horticulture, the spelling ''clon'' was used until the early twentieth century; the final ''e'' came into use to indicate the vowel is a "long o" instead of a "short o". Since the term entered the popular lexicon in a more general context, the spelling ''clone'' has been used exclusively. Natural cloning Cloning is a natural form of reproduction that has allowed life forms to spread for hundreds of millio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microbiota
Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found to be crucial for immunologic, hormonal, and metabolic homeostasis of their host. The term ''microbiome'' describes either the collective genomes of the microbes that reside in an ecological niche or within the microbes themselves. The microbiome and host emerged during evolution as a synergistic unit from epigenetics and genetic characteristics, sometimes collectively referred to as a holobiont. The presence of microbiota in human and other metazoan guts has been critical for understanding the co-evolution between metazoans and bacteria. Microbiota play key roles in the intestinal immune and metabolic responses via their fermentation product (short-chain fatty acid), acetate. Introduction All plants and animals, from simple life fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Barcoding
DNA barcoding is a method of species identification using a short section of DNA from a specific gene or genes. The premise of DNA barcoding is that by comparison with a reference library of such DNA sections (also called "sequences"), an individual sequence can be used to uniquely identify an organism to species, just as a supermarket scanner uses the familiar black stripes of the UPC barcode to identify an item in its stock against its reference database. These "barcodes" are sometimes used in an effort to identify unknown species or parts of an organism, simply to catalog as many taxa as possible, or to compare with traditional taxonomy in an effort to determine species boundaries. Different gene regions are used to identify the different organismal groups using barcoding. The most commonly used barcode region for animals and some protists is a portion of the cytochrome ''c'' oxidase I (COI or COX1) gene, found in mitochondrial DNA. Other genes suitable for DNA barcoding ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Center For Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is located in Bethesda, Maryland, and was founded in 1988 through legislation sponsored by US Congressman Claude Pepper. The NCBI houses a series of databases relevant to biotechnology and biomedicine and is an important resource for bioinformatics tools and services. Major databases include GenBank for DNA sequences and PubMed, a bibliographic database for biomedical literature. Other databases include the NCBI Epigenomics database. All these databases are available online through the Entrez search engine. NCBI was directed by David Lipman, one of the original authors of the BLAST sequence alignment program and a widely respected figure in bioinformatics. GenBank NCBI had responsibility for making available the GenBank DNA seque ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphology (biology)
Morphology is a branch of biology dealing with the study of the form and structure of organisms and their specific structural features. This includes aspects of the outward appearance (shape, structure, colour, pattern, size), i.e. external morphology (or eidonomy), as well as the form and structure of the internal parts like bones and organs, i.e. internal morphology (or anatomy). This is in contrast to physiology, which deals primarily with function. Morphology is a branch of life science dealing with the study of gross structure of an organism or taxon and its component parts. History The etymology of the word "morphology" is from the Ancient Greek (), meaning "form", and (), meaning "word, study, research". While the concept of form in biology, opposed to function, dates back to Aristotle (see Aristotle's biology), the field of morphology was developed by Johann Wolfgang von Goethe (1790) and independently by the German anatomist and physiologist Karl Friedrich Burdach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microscopy
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy. Optical microscopy and electron microscopy involve the diffraction, reflection, or refraction of electromagnetic radiation/electron beams interacting with the specimen, and the collection of the scattered radiation or another signal in order to create an image. This process may be carried out by wide-field irradiation of the sample (for example standard light microscopy and transmission electron microscopy) or by scanning a fine beam over the sample (for example confocal laser scanning microscopy and scanning electron microscopy). Scanning probe microscopy involves the interaction of a scanning probe with the surface of the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species Complex
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each other, further blurring any distinctions. Terms that are sometimes used synonymously but have more precise meanings are cryptic species for two or more species hidden under one species name, sibling species for two (or more) species that are each other's closest relative, and species flock for a group of closely related species that live in the same habitat. As informal taxonomic ranks, species group, species aggregate, macrospecies, and superspecies are also in use. Two or more taxa that were once considered conspecific (of the same species) may later be subdivided into infraspecific taxa (taxa within a species, such as bacterial strains or plant varieties), that is complex but it is not a species complex. A species complex is in most cas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') level. Biodiversity is not distributed evenly on Earth; it is usually greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than 10% of earth's surface and contain about 90% of the world's species. Marine biodiversity is usually higher along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future as a primary result of deforestation. It encompasses the evolutionary, ecological, and cultural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cistron
A cistron is an alternative term for "gene". The word cistron is used to emphasize that genes exhibit a specific behavior in a cis-trans test; distinct positions (or loci) within a genome are cistronic. History The words ''cistron'' and ''gene'' were coined before the advancing state of biology made it clear that the concepts they refer to are practically equivalent. The same historical naming practices are responsible for many of the synonyms in the life sciences. The term cistron was coined by Seymour Benzer in an article entitled ''The elementary units of heredity''. also reprinted in The cistron was defined by an operational test applicable to most organisms that is sometimes referred to as a cis-trans test, but more often as a complementation test. Definition For example, suppose a mutation at a chromosome position x is responsible for a change in recessive trait in a diploid organism (where chromosomes come in pairs). We say that the mutation is recessive because the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Transcribed Spacer
Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. ITS across life domains In bacteria and archaea, there is a single ITS, located between the 16S and 23S rRNA genes. Conversely, there are two ITSs in eukaryotes: ITS1 is located between 18S and 5.8S rRNA genes, while ITS2 is between 5.8S and 28S (in opisthokonts, or 25S in plants) rRNA genes. ITS1 corresponds to the ITS in bacteria and archaea, while ITS2 originated as an insertion that interrupted the ancestral 23S rRNA gene. Organization In bacteria and archaea, the ITS occurs in one to several copies, as do the flanking 16S and 23S genes. When there are multiple copies, these do not occur adjacent to one another. Rather, they occur in discrete locations in the circular chromosome. It is not uncommon in bacteria to carry tRN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Housekeeping Genes
In molecular biology, housekeeping genes are typically constitutive genes that are required for the maintenance of basic cellular function, and are expressed in all cells of an organism under normal and patho-physiological conditions. Although some housekeeping genes are expressed at relatively constant rates in most non-pathological situations, the expression of other housekeeping genes may vary depending on experimental conditions. The origin of the term "housekeeping gene" remains obscure. Literature from 1976 used the term to describe specifically tRNA and rRNA. For experimental purposes, the expression of one or multiple housekeeping genes is used as a reference point for the analysis of expression levels of other genes. The key criterion for the use of a housekeeping gene in this manner is that the chosen housekeeping gene is uniformly expressed with low variance under both control and experimental conditions. Validation of housekeeping genes should be performed before th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
