Misplaced Pages

#620379

62-399: The viral genus Lyssavirus , which includes the causative agent of rabies , was named after this goddess. Because seeds of alyssum were used (unsuccessfully) to treat rabies, the flower was named after the disease with the prefix α- in front, meaning without. Thus Lyssa is the etymological origin of the feminine name Alyssa . In Euripides ' play Herakles , Lyssa is identified as

124-468: A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses ). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA ), and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondria and

186-408: A mouse , the plant Arabidopsis thaliana , the puffer fish , and the bacteria E. coli . In December 2013, scientists first sequenced the entire genome of a Neanderthal , an extinct species of humans . The genome was extracted from the toe bone of a 130,000-year-old Neanderthal found in a Siberian cave . New sequencing technologies, such as massive parallel sequencing have also opened up

248-430: A big potential to modify the genetic control in a host organism. The movement of TEs is a driving force of genome evolution in eukaryotes because their insertion can disrupt gene functions, homologous recombination between TEs can produce duplications, and TE can shuffle exons and regulatory sequences to new locations. Retrotransposons are found mostly in eukaryotes but not found in prokaryotes. Retrotransposons form

310-506: A defined structure that are able to change their location in the genome. TEs are categorized as either as a mechanism that replicates by copy-and-paste or as a mechanism that can be excised from the genome and inserted at a new location. In the human genome, there are three important classes of TEs that make up more than 45% of the human DNA; these classes are The long interspersed nuclear elements (LINEs), The interspersed nuclear elements (SINEs), and endogenous retroviruses. These elements have

372-618: A genome sequence and aids in navigating around the genome. The Human Genome Project was organized to map and to sequence the human genome . A fundamental step in the project was the release of a detailed genomic map by Jean Weissenbach and his team at the Genoscope in Paris. Reference genome sequences and maps continue to be updated, removing errors and clarifying regions of high allelic complexity. The decreasing cost of genomic mapping has permitted genealogical sites to offer it as

434-534: A large portion of the genomes of many eukaryotes. A retrotransposon is a transposable element that transposes through an RNA intermediate. Retrotransposons are composed of DNA , but are transcribed into RNA for transposition, then the RNA transcript is copied back to DNA formation with the help of a specific enzyme called reverse transcriptase. A retrotransposon that carries reverse transcriptase in its sequence can trigger its own transposition but retrotransposons that lack

496-531: A mad rage that causes him to murder his wife and children. In a number of ancient Greek vases Lyssa appears on the scene of the death of Actaeon , the hunter who was transformed into a deer and devoured by his own hounds for seeing Artemis naked or trying to woo Semele . In a 440s BC red-figure bell-krater by the Lykaon Painter , Lyssa stands to the right of Actaeon, inflicting his dogs with rabies and directing them against him. It has been theorised that

558-405: A main driving role to generate genetic novelty and natural genome editing. Works of science fiction illustrate concerns about the availability of genome sequences. Michael Crichton's 1990 novel Jurassic Park and the subsequent film tell the story of a billionaire who creates a theme park of cloned dinosaurs on a remote island, with disastrous outcomes. A geneticist extracts dinosaur DNA from

620-413: A major role in shaping the genome. Duplication may range from extension of short tandem repeats , to duplication of a cluster of genes, and all the way to duplication of entire chromosomes or even entire genomes . Such duplications are probably fundamental to the creation of genetic novelty. Horizontal gene transfer is invoked to explain how there is often an extreme similarity between small portions of

682-467: A major theme of the book. The 1997 film Gattaca is set in a futurist society where genomes of children are engineered to contain the most ideal combination of their parents' traits, and metrics such as risk of heart disease and predicted life expectancy are documented for each person based on their genome. People conceived outside of the eugenics program, known as "In-Valids" suffer discrimination and are relegated to menial occupations. The protagonist of

SECTION 10

#1732776668621

744-888: A negative-sense, single-stranded RNA molecule that encodes five viral proteins: polymerase L, matrix protein M, phosphoprotein P, nucleoprotein N, and glycoprotein G. Genomes are linear, around 11kb in length. Based on recent phylogenetic evidence, lyssaviruses have been categorized into seven major species . In addition, five more species have recently been discovered: West Caucasian bat virus, Aravan virus, Khujand virus, Irkut virus and Shimoni bat virus. The lyssavirus genus can be divided into four phylogroups based upon DNA sequence homology. Phylogroup I includes viruses, such as Rabies virus, Duvenhage virus, European bat lyssavirus types 1 and 2, Australian bat lyssavirus, Khujand virus, Bokeloh bat lyssavirus, Irkut virus, and Aravan virus. Phylogroup II contains Lagos bat virus, Mokola virus, and Shimoni bat virus. West Caucasian bat lyssavirus

806-477: A new site. This cut-and-paste mechanism typically reinserts transposons near their original location (within 100 kb). DNA transposons are found in bacteria and make up 3% of the human genome and 12% of the genome of the roundworm C. elegans . Genome size is the total number of the DNA base pairs in one copy of a haploid genome. Genome size varies widely across species. Invertebrates have small genomes, this

868-501: A precise definition of "genome." It usually refers to the DNA (or sometimes RNA) molecules that carry the genetic information in an organism but sometimes it is difficult to decide which molecules to include in the definition; for example, bacteria usually have one or two large DNA molecules ( chromosomes ) that contain all of the essential genetic material but they also contain smaller extrachromosomal plasmid molecules that carry important genetic information. The definition of 'genome' that

930-463: A real-time PCR machine and skilled workers with experience in molecular diagnostics. In an international evaluation a single TaqMan LN34 assay could detect Lyssavirus with high sensitivity (99.90%) across the genus and high specificity (99.68%) when compared to the DFA test. It will become the primary post-mortem rabies diagnostic test where possible. Classic rabies virus is prevalent throughout most of

992-415: A reference, whereas analyses of coverage depth and mapping topology can provide details regarding structural variations such as chromosomal translocations and segmental duplications. DNA sequences that carry the instructions to make proteins are referred to as coding sequences. The proportion of the genome occupied by coding sequences varies widely. A larger genome does not necessarily contain more genes, and

1054-487: A reverse transcriptase must use reverse transcriptase synthesized by another retrotransposon. Retrotransposons can be transcribed into RNA, which are then duplicated at another site into the genome. Retrotransposons can be divided into long terminal repeats (LTRs) and non-long terminal repeats (Non-LTRs). Long terminal repeats (LTRs) are derived from ancient retroviral infections, so they encode proteins related to retroviral proteins including gag (structural proteins of

1116-522: A role in the myth of Lycurgus , the Thracian king who tried to ban the worship of Dionysus , the god of madness. In an Apulian vase from around 350 BC, the winged Lyssa supplants Dionysus as the deity causing Lycurgus to attack and kill his wife and son. Aeschylus identifies her as being the agent sent by Dionysus to madden the impious daughters of Cadmus , who in turn dismember their kinsman Pentheus . Lyssavirus Lyssavirus (from

1178-651: A service, to the extent that one may submit one's genome to crowdsourced scientific endeavours such as DNA.LAND at the New York Genome Center , an example both of the economies of scale and of citizen science . Viral genomes can be composed of either RNA or DNA. The genomes of RNA viruses can be either single-stranded RNA or double-stranded RNA , and may contain one or more separate RNA molecules (segments: monopartit or multipartit genome). DNA viruses can have either single-stranded or double-stranded genomes. Most DNA virus genomes are composed of

1240-404: A single, linear molecule of DNA, but some are made up of a circular DNA molecule. Prokaryotes and eukaryotes have DNA genomes. Archaea and most bacteria have a single circular chromosome , however, some bacterial species have linear or multiple chromosomes. If the DNA is replicated faster than the bacterial cells divide, multiple copies of the chromosome can be present in a single cell, and if

1302-518: A small mitochondrial genome . Algae and plants also contain chloroplasts with a chloroplast genome. The study of the genome is called genomics . The genomes of many organisms have been sequenced and various regions have been annotated. The Human Genome Project was started in October 1990, and then reported the sequence of the human genome in April 2003, although the initial "finished" sequence

SECTION 20

#1732776668621

1364-560: A species. Within a species, the vast majority of nucleotides are identical between individuals, but sequencing multiple individuals is necessary to understand the genetic diversity. In 1976, Walter Fiers at the University of Ghent (Belgium) was the first to establish the complete nucleotide sequence of a viral RNA-genome ( Bacteriophage MS2 ). The next year, Fred Sanger completed the first DNA-genome sequence: Phage Φ-X174 , of 5386 base pairs. The first bacterial genome to be sequenced

1426-485: Is also correlated to a small number of transposable elements. Fish and Amphibians have intermediate-size genomes, and birds have relatively small genomes but it has been suggested that birds lost a substantial portion of their genomes during the phase of transition to flight.  Before this loss, DNA methylation allows the adequate expansion of the genome. In humans, the nuclear genome comprises approximately 3.1 billion nucleotides of DNA, divided into 24 linear molecules,

1488-432: Is another DIRS-like elements belong to Non-LTRs. Non-LTRs are widely spread in eukaryotic genomes. Long interspersed elements (LINEs) encode genes for reverse transcriptase and endonuclease, making them autonomous transposable elements. The human genome has around 500,000 LINEs, taking around 17% of the genome. Short interspersed elements (SINEs) are usually less than 500 base pairs and are non-autonomous, so they rely on

1550-444: Is carried in plasmids . For this, the word genome should not be used as a synonym of chromosome . Eukaryotic genomes are composed of one or more linear DNA chromosomes. The number of chromosomes varies widely from Jack jumper ants and an asexual nemotode , which each have only one pair, to a fern species that has 720 pairs. It is surprising the amount of DNA that eukaryotic genomes contain compared to other genomes. The amount

1612-408: Is commonly used in the scientific literature is usually restricted to the large chromosomal DNA molecules in bacteria. Eukaryotic genomes are even more difficult to define because almost all eukaryotic species contain nuclear chromosomes plus extra DNA molecules in the mitochondria . In addition, algae and plants have chloroplast DNA. Most textbooks make a distinction between the nuclear genome and

1674-564: Is even more than what is necessary for DNA protein-coding and noncoding genes due to the fact that eukaryotic genomes show as much as 64,000-fold variation in their sizes. However, this special characteristic is caused by the presence of repetitive DNA, and transposable elements (TEs). A typical human cell has two copies of each of 22 autosomes , one inherited from each parent, plus two sex chromosomes , making it diploid. Gametes , such as ova, sperm, spores, and pollen, are haploid, meaning they carry only one copy of each chromosome. In addition to

1736-492: Is facilitated by active DNA demethylation , a process that entails the DNA base excision repair pathway. This pathway is employed in the erasure of CpG methylation (5mC) in primordial germ cells. The erasure of 5mC occurs via its conversion to 5-hydroxymethylcytosine (5hmC) driven by high levels of the ten-eleven dioxygenase enzymes TET1 and TET2 . Genomes are more than the sum of an organism's genes and have traits that may be measured and studied without reference to

1798-529: Is further work to be done in this area. Although bats evolved in the Palearctic, their origins antedate that of the lyssaviruses by millions of years, which argues against their co-speciation. The evolution rate in the N gene in the Africa 2 lineage has been estimated to be 3.75×10 substitutions per site per year. This rate is similar to that of other RNA viruses. Viral replication is cytoplasmic. Entry into

1860-401: Is rather exceptional, eukaryotes generally have these features in their genes and their genomes contain variable amounts of repetitive DNA. In mammals and plants, the majority of the genome is composed of repetitive DNA. High-throughput technology makes sequencing to assemble new genomes accessible to everyone. Sequence polymorphisms are typically discovered by comparing resequenced isolates to

1922-445: Is the only virus that is a part of phylogroup III. Ikoma lyssavirus and Lleida bat lyssavirus are examples in phylogroup IV. West Caucasian bat lyssavirus was classified within its own phylogroup because it is the most divergent lyssavirus that has been discovered. Phylogenetic studies suggest that the original hosts of these viruses were bats. However, the recent discovery of lyssavirus sequences from amphibians and reptiles challenges

Lyssa - Misplaced Pages Continue

1984-421: Is to reduce the number of genes in a genome to the bare minimum and still have the organism in question survive. There is experimental work being done on minimal genomes for single cell organisms as well as minimal genomes for multi-cellular organisms (see developmental biology ). The work is both in vivo and in silico . There are many enormous differences in size in genomes, specially mentioned before in

2046-402: Is typical of plant-infecting viruses. Virions of human-infecting viruses more commonly have cubic symmetry and take shapes approximating regular polyhedra . The structure consists of a spiked outer envelope , a middle region consisting of matrix protein M, and an inner ribonucleocapsid complex region, consisting of the genome associated with other proteins. Lyssavirus genomes consist of

2108-648: The Greek λύσσα lyssa "rage, fury, rabies" and the Latin vīrus ) is a genus of RNA viruses in the family Rhabdoviridae , order Mononegavirales . Mammals, including humans, can serve as natural hosts . The genus Lyssavirus includes the causative agent ( rabies virus ) of rabies . Lyssavirions are enveloped, with bullet shaped geometries. These virions are about 75 nm wide and 180 nm long. Lyssavirions have helical symmetry, so their infectious particles are approximately cylindrical in shape. This

2170-498: The University of Hamburg , Germany. The website Oxford Dictionaries and the Online Etymology Dictionary suggest the name is a blend of the words gene and chromosome . However, see omics for a more thorough discussion. A few related -ome words already existed, such as biome and rhizome , forming a vocabulary into which genome fits systematically. It is very difficult to come up with

2232-434: The direct fluorescent antibody (DFA) test is still the gold standard to detect lyssavirus infection. Since the new millennium reverse transcription PCR (RT-PCR) tests have been developed for rabies but only been used as a confirmatory test. Real-time PCR -based tests which have higher sensitivity and objective diagnostic thresholds and allow samples to be stored at room temperature have been promising since 2005, but require

2294-426: The X and Y chromosomes of mammals, so the technical definition of the genome must include both copies of the sex chromosomes. For example, the standard reference genome of humans consists of one copy of each of the 22 autosomes plus one X chromosome and one Y chromosome. A genome sequence is the complete list of the nucleotides (A, C, G, and T for DNA genomes) that make up all the chromosomes of an individual or

2356-412: The blood of ancient mosquitoes and fills in the gaps with DNA from modern species to create several species of dinosaurs. A chaos theorist is asked to give his expert opinion on the safety of engineering an ecosystem with the dinosaurs, and he repeatedly warns that the outcomes of the project will be unpredictable and ultimately uncontrollable. These warnings about the perils of using genomic information are

2418-549: The cells divide faster than the DNA can be replicated, multiple replication of the chromosome is initiated before the division occurs, allowing daughter cells to inherit complete genomes and already partially replicated chromosomes. Most prokaryotes have very little repetitive DNA in their genomes. However, some symbiotic bacteria (e.g. Serratia symbiotica ) have reduced genomes and a high fraction of pseudogenes: only ~40% of their DNA encodes proteins. Some bacteria have auxiliary genetic material, also part of their genome, which

2480-478: The chromosomes in the nucleus, organelles such as the chloroplasts and mitochondria have their own DNA. Mitochondria are sometimes said to have their own genome often referred to as the " mitochondrial genome ". The DNA found within the chloroplast may be referred to as the " plastome ". Like the bacteria they originated from, mitochondria and chloroplasts have a circular chromosome. Unlike prokaryotes where exon-intron organization of protein coding genes exists but

2542-400: The daughter of the night-goddess Nyx , "sprung from the blood of Uranus "—that is, the blood from Uranus' wound following his castration by his son Cronus . The 1st-century Latin writer Hyginus lists Ira (Wrath, Lyssa) as the daughter of Terra ( Gaia ) and Aether . Lyssa personifies mad rage and frenzy, as well as rabies in animals. In Herakles , she is called upon by Hera to inflict

Lyssa - Misplaced Pages Continue

2604-445: The details of any particular genes and their products. Researchers compare traits such as karyotype (chromosome number), genome size , gene order, codon usage bias , and GC-content to determine what mechanisms could have produced the great variety of genomes that exist today (for recent overviews, see Brown 2002; Saccone and Pesole 2003; Benfey and Protopapas 2004; Gibson and Muse 2004; Reese 2004; Gregory 2005). Duplications play

2666-406: The genomes of two organisms that are otherwise very distantly related. Horizontal gene transfer seems to be common among many microbes . Also, eukaryotic cells seem to have experienced a transfer of some genetic material from their chloroplast and mitochondrial genomes to their nuclear chromosomes. Recent empirical data suggest an important role of viruses and sub-viral RNA-networks to represent

2728-412: The hero Heracles with insanity. In this scenario, she is shown to take a temperate, measured approach to her role, professing "not to use [her powers] in anger against friends, nor [to] have any joy in visiting the homes of men." She counsels Iris, who wishes to carry out Hera's command, against targeting Heracles but, after failing to persuade, bows to the orders of the superior goddess and sends him into

2790-534: The host cell is achieved by attachment of the viral G glycoproteins to host receptors, which mediates clathrin-mediated endocytosis . Replication follows the negative stranded RNA virus replication model. Negative stranded RNA virus transcription, using polymerase stuttering , is the method of transcription. The virus exits the host cell by budding and by tubule-guided viral movement. Wild mammals, especially bats and certain carnivores, serve as natural hosts. Transmission routes are typically via bite wounds. As of 2018

2852-455: The human genome All the cells of an organism originate from a single cell, so they are expected to have identical genomes; however, in some cases, differences arise. Both the process of copying DNA during cell division and exposure to environmental mutagens can result in mutations in somatic cells. In some cases, such mutations lead to cancer because they cause cells to divide more quickly and invade surrounding tissues. In certain lymphocytes in

2914-425: The human genome and 9% of the fruit fly genome. Tandem repeats can be functional. For example, telomeres are composed of the tandem repeat TTAGGG in mammals, and they play an important role in protecting the ends of the chromosome. In other cases, expansions in the number of tandem repeats in exons or introns can cause disease . For example, the human gene huntingtin (Htt) typically contains 6–29 tandem repeats of

2976-517: The human immune system, V(D)J recombination generates different genomic sequences such that each cell produces a unique antibody or T cell receptors. During meiosis , diploid cells divide twice to produce haploid germ cells. During this process, recombination results in a reshuffling of the genetic material from homologous chromosomes so each gamete has a unique genome. Genome-wide reprogramming in mouse primordial germ cells involves epigenetic imprint erasure leading to totipotency . Reprogramming

3038-505: The mammalian origin of lyssaviruses. The greater antigenic diversity of lyssaviruses from Africa has led to the assumption that Africa was the origin of these viruses. An examination of 153 viruses collected between 1956 and 2015 from various geographic locations has instead suggested a Palearctic origin (85% likelihood) for these viruses. Date estimates (95% likelihood) for the most recent common ancestor were very broad – between 3,995 and 166,820 years before present – which suggests there

3100-476: The multicellular eukaryotic genomes. Much of this is due to the differing abundances of transposable elements, which evolve by creating new copies of themselves in the chromosomes. Eukaryote genomes often contain many thousands of copies of these elements, most of which have acquired mutations that make them defective. Here is a table of some significant or representative genomes. See #See also for lists of sequenced genomes. Initial sequencing and analysis of

3162-795: The nucleotides CAG (encoding a polyglutamine tract). An expansion to over 36 repeats results in Huntington's disease , a neurodegenerative disease. Twenty human disorders are known to result from similar tandem repeat expansions in various genes. The mechanism by which proteins with expanded polygulatamine tracts cause death of neurons is not fully understood. One possibility is that the proteins fail to fold properly and avoid degradation, instead accumulating in aggregates that also sequester important transcription factors, thereby altering gene expression. Tandem repeats are usually caused by slippage during replication, unequal crossing-over and gene conversion. Transposable elements (TEs) are sequences of DNA with

SECTION 50

#1732776668621

3224-447: The organelle (mitochondria and chloroplast) genomes so when they speak of, say, the human genome, they are only referring to the genetic material in the nucleus. This is the most common use of 'genome' in the scientific literature. Most eukaryotes are diploid , meaning that there are two of each chromosome in the nucleus but the 'genome' refers to only one copy of each chromosome. Some eukaryotes have distinctive sex chromosomes, such as

3286-590: The proportion of non-repetitive DNA decreases along with increasing genome size in complex eukaryotes. Noncoding sequences include introns , sequences for non-coding RNAs, regulatory regions, and repetitive DNA. Noncoding sequences make up 98% of the human genome. There are two categories of repetitive DNA in the genome: tandem repeats and interspersed repeats. Short, non-coding sequences that are repeated head-to-tail are called tandem repeats . Microsatellites consisting of 2–5 basepair repeats, while minisatellite repeats are 30–35 bp. Tandem repeats make up about 4% of

3348-412: The prospect of personal genome sequencing as a diagnostic tool, as pioneered by Manteia Predictive Medicine . A major step toward that goal was the completion in 2007 of the full genome of James D. Watson , one of the co-discoverers of the structure of DNA. Whereas a genome sequence lists the order of every DNA base in a genome, a genome map identifies the landmarks. A genome map is less detailed than

3410-439: The proteins encoded by LINEs for transposition. The Alu element is the most common SINE found in primates. It is about 350 base pairs and occupies about 11% of the human genome with around 1,500,000 copies. DNA transposons encode a transposase enzyme between inverted terminal repeats. When expressed, the transposase recognizes the terminal inverted repeats that flank the transposon and catalyzes its excision and reinsertion in

3472-423: The shortest 45 000 000 nucleotides in length and the longest 248 000 000 nucleotides, each contained in a different chromosome. There is no clear and consistent correlation between morphological complexity and genome size in either prokaryotes or lower eukaryotes . Genome size is largely a function of the expansion and contraction of repetitive DNA elements. Since genomes are very complex, one research strategy

3534-503: The vase depicts the events of the myth as dramatised in Athenian tragedian Aeschylus ' lost play Toxotides which dealt with Actaeon's death, although this assertion is far from certain. In a different vase with Actaeon's death, Lyssa is present along with Aphrodite , Eros , Artemis and a woman that could be Semele, indicating a sexual nature of Actaeon's grave offence which led to him being eaten by his own rabid dogs. Lyssa also had

3596-541: The virus), pol (reverse transcriptase and integrase), pro (protease), and in some cases env (envelope) genes. These genes are flanked by long repeats at both 5' and 3' ends. It has been reported that LTRs consist of the largest fraction in most plant genome and might account for the huge variation in genome size. Non-long terminal repeats (Non-LTRs) are classified as long interspersed nuclear elements (LINEs), short interspersed nuclear elements (SINEs), and Penelope-like elements (PLEs). In Dictyostelium discoideum , there

3658-482: The world and can be carried by any warm blooded mammal. The other lyssaviruses have much less diversity in carriers. Only select hosts can carry each of these viral species . Also, these other species are particular only to a specific geographic area. Bats are known to be an animal vector for all identified lyssaviruses except the Mokola virus . Genome In the fields of molecular biology and genetics ,

3720-429: Was completed in 1996, again by The Institute for Genomic Research. The development of new technologies has made genome sequencing dramatically cheaper and easier, and the number of complete genome sequences is growing rapidly. The US National Institutes of Health maintains one of several comprehensive databases of genomic information. Among the thousands of completed genome sequencing projects include those for rice ,

3782-477: Was missing 8% of the genome consisting mostly of repetitive sequences. With advancements in technology that could handle sequencing of the many repetitive sequences found in human DNA that were not fully uncovered by the original Human Genome Project study, scientists reported the first end-to-end human genome sequence in March 2022. The term genome was created in 1920 by Hans Winkler , professor of botany at

SECTION 60

#1732776668621

3844-400: Was that of Haemophilus influenzae , completed by a team at The Institute for Genomic Research in 1995. A few months later, the first eukaryotic genome was completed, with sequences of the 16 chromosomes of budding yeast Saccharomyces cerevisiae published as the result of a European-led effort begun in the mid-1980s. The first genome sequence for an archaeon , Methanococcus jannaschii ,

#620379