Evolutionary developmental biology is a field of biological research that compares the developmental processes of different organisms to infer how developmental processes evolved.
A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. Mutations in a homeobox may change large-scale anatomical features of the full-grown organism.
In evolutionary developmental biology, homeosis is the transformation of one organ into another, arising from mutation in or misexpression of certain developmentally critical genes, specifically homeotic genes. In animals, these developmental genes specifically control the development of organs on their anteroposterior axis. In plants, however, the developmental genes affected by homeosis may control anything from the development of a stamen or petals to the development of chlorophyll. Homeosis may be caused by mutations in Hox genes, found in animals, or others such as the MADS-box family in plants. Homeosis is a characteristic that has helped insects become as successful and diverse as they are.
Hox genes, a subset of homeobox genes, are a group of related genes that specify regions of the body plan of an embryo along the head-tail axis of animals. Hox proteins encode and specify the characteristics of 'position', ensuring that the correct structures form in the correct places of the body. For example, Hox genes in insects specify which appendages form on a segment, and Hox genes in vertebrates specify the types and shape of vertebrae that will form. In segmented animals, Hox proteins thus confer segmental or positional identity, but do not form the actual segments themselves.
Antennapedia is a Hox gene first discovered in Drosophila which controls the formation of legs during development. Loss-of-function mutations in the regulatory region of this gene result in the development of the second leg pair into ectopic antennae. By contrast gain-of-function alleles convert antennae into ectopic legs.
Limb development in vertebrates is an area of active research in both developmental and evolutionary biology, with much of the latter work focused on the transition from fin to limb.
Homeobox protein Hox-B6 is a protein that in humans is encoded by the HOXB6 gene.
Homeobox protein Hox-B5 is a protein that in humans is encoded by the HOXB5 gene.
Homeobox protein Hox-C8 is a protein that in humans is encoded by the HOXC8 gene.
Homeobox protein Hox-D13 is a protein that in humans is encoded by the HOXD13 gene. This gene belongs to the homeobox family of genes. The homeobox genes encode a highly conserved family of transcription factors that play an important role in morphogenesis in all multicellular organisms.
Homeobox protein Hox-B13 is a protein that in humans is encoded by the HOXB13 gene.
Homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, insects, mammals, and plants. Homeotic genes often encode transcription factor proteins, and these proteins affect development by regulating downstream gene networks involved in body patterning.
Homeotic selector genes confer segment identity in Drosophila. They encode homeodomain proteins which interact with Hox and other homeotic genes to initiate segment-specific gene regulation. Homeodomain proteins are transcription factors that share a DNA-binding domain called the homeodomain. Changes in the expression and function of homeotic genes are responsible for the changes in the morphology of the limbs of arthropods as well as in the axial skeletons of vertebrates. Mutations in homeotic selector genes do not lead to elimination of a segment or pattern, but instead cause the segment to develop incorrectly.
Edward Michael De Robertis is an American embryologist and Professor at the University of California, Los Angeles. His work has contributed to the finding of conserved molecular processes of embryonic inductions that result in tissue differentiations during animal development. He was elected to the National Academy of Sciences in 2013, worked for the Howard Hughes Medical Institute for 26 years, and holds a Distinguished Professor at the University of California, Los Angeles. In 2009 Pope Benedict XVI appointed De Robertis to a lifetime position in the Pontifical Academy of Sciences, and in 2022 Pope Francis appointed him Councillor of the Academy for four years.
Zerknüllt is a gene in the Antennapedia complex of Drosophila and other insects, where it operates very differently from the canonical Hox genes in the same gene cluster. Comparison of Hox genes between species showed that the Zerknüllt gene evolved from one of the standard Hox genes in insects through accumulating many amino acid changes, changing expression pattern, losing ancestral function and gaining a new function.
Michael Levine is an American developmental and cell biologist at Princeton University, where he is the Director of the Lewis-Sigler Institute for Integrative Genomics and a Professor of Molecular Biology.
The Gsx gene family are a group of genes found in many, but not all, animals. Gsx genes contain a homeobox DNA sequence and code for proteins that act as transcription factors. The human genome has two Gsx genes, called GSX1 and GSX2, while the fruitfly Drosophila has a single Gsx gene called ind. Vertebrate Gsx genes are implicated in neural patterning. In many animals, Gsx genes can be part of a ParaHox gene cluster.
Hox genes play a massive role in some amphibians and reptiles in their ability to regenerate lost limbs, especially HoxA and HoxD genes.
The evo-devo gene toolkit is the small subset of genes in an organism's genome whose products control the organism's embryonic development. Toolkit genes are central to the synthesis of molecular genetics, palaeontology, evolution and developmental biology in the science of evolutionary developmental biology (evo-devo). Many of them are ancient and highly conserved among animal phyla.
Robb Krumlauf is an American developmental biologist. He is best known for researching the Hox family of transcription factors. He is most interested in understanding the role of the Hox genes in the hindbrain and their role in areas of animal development, such as craniofacial development. Krumlauf worked with a variety of renowned scientists in the field of developmental biology throughout his time researching Hox genes.
