Conserved sequence in the context of Segregating site

Evolutionary developmental biology, informally known as evo-devo, is a field of biological research that compares the developmental processes of different organisms to infer how developmental processes evolved.

The field grew from 19th-century beginnings, where embryology faced a mystery: zoologists did not know how embryonic development was controlled at the molecular level. Charles Darwin noted that having similar embryos implied common ancestry, but little progress was made until the 1970s. Then, recombinant DNA technology at last brought embryology together with molecular genetics. A key early discovery was that of homeotic genes that regulate development in a wide range of eukaryotes.

The nuclear pore complex (NPC), is a large protein complex giving rise to the nuclear pore. A great number of nuclear pores are studded throughout the nuclear envelope that surrounds the eukaryote cell nucleus. The pores enable the nuclear transport of macromolecules between the nucleoplasm of the nucleus and the cytoplasm of the cell. Small molecules can easily diffuse through the pores. Nuclear transport includes the transportation of RNA and ribosomal proteins from the nucleus to the cytoplasm, and the transport of proteins (such as DNA polymerase and lamins), carbohydrates, signaling molecules, and lipids into the nucleus. Each nuclear pore complex can actively mediate up to 1000 translocations per second.

The nuclear pore complex consists predominantly of a family of proteins known as nucleoporins (Nups). Each pore complex in the human cell nucleus is composed of about 1,000 individual protein molecules, from an evolutionarily conserved set of 35 distinct nucleoporins. The conserved sequences that code for nucleoporins regulate molecular transport through the nuclear pore. Nucleoporin-mediated transport does not entail direct energy expenditure but instead relies on concentration gradients associated with the RAN cycle (Ras-related nuclear protein cycle). In 2022 around 90% of the structure of the human NPC was elucidated in an open and a closed conformation, and published in a special issue of Science, featured on the cover. In 2024 the structure of the nuclear basket was solved, finalising the completion of the structure of the nuclear pore complex.

In cellular biology, the Wnt signaling pathways are a group of signal transduction pathways which begin with proteins that pass signals into a cell through cell surface receptors. The name Wnt, pronounced "wint", is a portmanteau created from the names Wingless and Int-1. Wnt signaling pathways use either nearby cell-cell communication (paracrine) or same-cell communication (autocrine). They are highly evolutionarily conserved in animals, which means they are similar across animal species from fruit flies to humans.

Three Wnt signaling pathways have been characterized: the canonical Wnt pathway, the noncanonical planar cell polarity pathway, and the noncanonical Wnt/calcium pathway. All three pathways are activated by the binding of a Wnt-protein ligand to a Frizzled family receptor, which passes the biological signal to the Dishevelled protein inside the cell. The canonical Wnt pathway leads to regulation of gene transcription, and is thought to be negatively regulated in part by the SPATS1 gene. The noncanonical planar cell polarity pathway regulates the cytoskeleton that is responsible for the shape of the cell. The noncanonical Wnt/calcium pathway regulates calcium inside the cell.

Helicases are a class of enzymes that are vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic double helix, separating the two hybridized nucleic acid strands (hence helic- + -ase), via the energy gained from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases.

The human genome codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. Many cellular processes, such as DNA replication, transcription, translation, recombination, DNA repair and ribosome biogenesis involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are also involved in sensing viral nucleic acids during infection and fulfill an immunological function. Genetic mutations that affect helicases can have wide-reaching impacts for an organism, due to their significance in many biological processes.

A conserved non-coding sequence (CNS) is a DNA sequence of noncoding DNA that is evolutionarily conserved. Sequence conservation is a useful marker of function, so conserved non-coding sequences are functional elements of the genome other than coding DNA.

Some of these functional elements include non-coding genes, regulatory sequences, scaffold attachment regions; origins of DNA replication; centromeres; and telomeres (see Non-coding DNA).

In bioinformatics, a sequence alignment is a way of arranging the sequences of DNA, RNA, or protein to identify regions of similarity that may be a consequence of functional, structural, or evolutionary relationships between the sequences. Aligned sequences of nucleotide or amino acid residues are typically represented as rows within a matrix. Gaps are inserted between the residues so that identical or similar characters are aligned in successive columns.Sequence alignments are also used for non-biological sequences such as calculating the distance cost between strings in a natural language, or to display financial data.

Histone H1 is one of the five main histone protein families which are components of chromatin in eukaryotic cells. Though highly conserved, it is nevertheless the most variable histone in sequence across species.

Thymic involution is the shrinking (involution) of the thymus with age, resulting in changes in the architecture of the thymus and a decrease in tissue mass. Thymus involution is one of the major characteristics of vertebrate immunology, and occurs in almost all vertebrates, from birds, teleosts, amphibians to reptiles, although the thymi of a few species of sharks are known not to involute. This process is genetically regulated, with the nucleic material responsible forming an example of a conserved sequence — one maintained through natural selection (though the pressures shaping this are unclear as will be discussed) since it arose in a common ancestor of all species now exhibiting it, via a phenomenon known to bioinformaticists as an orthologic sequence homology.

T-cells are named for the thymus where T-lymphocytes migrate from bone marrow to mature. Its regression has been linked to a reduction in immunosurveillance and the rise of infectious disease and cancer incidence in the elderly (in some cases risk is inversely proportional to thymus size). Though thymic involution has been linked to immunosenescence, it is not induced by senescence as the organ starts involuting from a young age: in humans, as early as the first year after birth.

In virology, realm is the highest taxonomic rank established for viruses by the International Committee on Taxonomy of Viruses (ICTV), which oversees virus taxonomy. Six virus realms are recognized and united by specific highly conserved traits:

• Adnaviria, which contains archaeal filamentous viruses with A-form double-stranded (ds) DNA genomes encoding a unique alpha-helical major capsid protein;
• Duplodnaviria, which contains all dsDNA viruses that encode the HK97-fold major capsid protein;
• Monodnaviria, which contains all single-stranded DNA (ssDNA) viruses that encode an HUH superfamily endonuclease and their descendants;
• Riboviria, which contains all RNA viruses that encode RNA-dependent RNA polymerase and all viruses that encode reverse transcriptase;
• Ribozyviria, which contains hepatitis delta virus-like viruses with circular, negative-sense ssRNA genomes;
• Singelaviria, which contains all DNA viruses that have two major capsid proteins (MCPs) that both have a single jelly roll (SJR) fold;
• and Varidnaviria, which contains all dsDNA viruses that encode a vertical jelly roll major capsid protein.

The rank of realm corresponds to the rank of domain used for cellular life, but differs in that viruses in a realm do not necessarily share a common ancestor based on common descent nor do the realms share a common ancestor. Instead, realms group viruses together based on specific traits that are highly conserved over time, which may have been obtained on a single occasion or multiple occasions. As such, each realm represents at least one instance of viruses coming into existence. While historically it was difficult to determine deep evolutionary relations between viruses, in the 21st century methods such as metagenomics and cryogenic electron microscopy have enabled such research to occur, which led to the establishment of Riboviria in 2018, three realms in 2019, and two in 2020.