Civil Rights
Movements, leaders, victories and the continuing fight for equality.
Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Paired related homeobox 1 is a protein that in humans is encoded by the PRRX1 gene.[5][6]
The DNA-associated protein encoded by this gene is a member of the paired family of homeobox proteins localized to the nucleus. The protein functions as a transcription coactivator, enhancing the DNA-binding activity of serum response factor, a protein required for the induction of genes by growth and differentiation factors. The protein regulates muscle creatine kinase, indicating a role in the establishment of diverse mesodermal muscle types. Alternative splicing yields two isoforms that differ in abundance and expression patterns.[6]
Prrx1 expression is restricted to the mesoderm during embryonic development, and both Prrx1 and Prrx2 are expressed in mesenchymal tissues in adult mice.[7][8][9][10][11] Mice that lack both Prrx1 and Prrx2 have profound defects in mesenchymal cell differentiation in the craniofacial region.[9][12] Several recent studies demonstrate that PRRX1 can regulate differentiation of mesenchymal precursors. For example, PRRX1 inhibits adipogenesis by activating transforming growth factor-beta (TGF-beta) signaling,[13] and also acts downstream of tumor necrosis factor-alpha to inhibit osteoblast differentiation.[14]
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
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Paired related homeobox 1 is a protein that in humans is encoded by the PRRX1 gene.
Homeobox protein aristaless-like 4 is a protein that in humans is encoded by the ALX4 gene. Alx4 belongs to the group-1 aristaless-related genes, a majority of which are linked to the development of the craniofacial and/or appendicular skeleton, along with PRRX1, SHOX, ALX3, and CART1. The Alx4 protein acts as a transcriptional activator and is predominantly expressed in the mesenchyme of the developing embryonic limb buds. Transcripts of this gene are detectable in the lateral plate mesoderm just prior to limb induction. Alx4 expression plays a major role in the determination of spatial orientation of the growing limb bud by aiding in the establishment of anteroposterior polarity of the limb. It does this by working in conjunction with Gli3 and dHand to restrict the expression of Sonic Hedgehog (SHh) to the posterior mesenchyme, which will eventually give rise to the Zone of Polarizing Activity (ZPA). This gene has been proven to be allelic with mutations and deletions giving rise to a host of craniofacial dismorphologies and several forms of polydactyly in mammalian development. A mouse-model knockout of this gene, dubbed Strong's luxoid, was originally created by Forstheofel in the 1960s and has been extensively studied to understand the partial and complete loss-of-function properties of this gene.
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. Homeoboxes are found within genes that are involved in the regulation of patterns of anatomical development (morphogenesis) in animals, fungi, plants, and numerous single cell eukaryotes. Homeobox genes encode homeodomain protein products that are transcription factors sharing a characteristic protein fold structure that binds DNA to regulate expression of target genes. Homeodomain proteins regulate gene expression and cell differentiation during early embryonic development, thus mutations in homeobox genes can cause developmental disorders. Homeosis is a term coined by William Bateson to describe the outright replacement of a discrete body part with another body part, e.g. antennapedia—replacement of the antenna on the head of a fruit fly with legs. The "homeo-" prefix in the words "homeobox" and "homeodomain" stems from this mutational phenotype, which is observed when some of these genes are mutated in animals. The homeobox domain was first identified in a number of Drosophila homeotic and segmentation proteins, but is now known to be well-conserved in many other animals, including vertebrates.
The evolution of cetaceans is thought to have proceeded in modern day Pakistan during the Eocene epoch (56–34 mya), the second epoch of the Paleogene period of the present-extending Cenozoic Era. Specifically, cetaceans are thought to have transitioned from land to water at the tailend of the Paleocene–Eocene transition about 56 Mya, which was marked by increased global temperatures of 5.6°C, warming the earth’s oceans. Cetaceans are fully aquatic mammals belonging to the order Artiodactyla. Molecular and morphological analyses suggest that they share a relatively recent closest common ancestor with hippopotamuses – their sister group, diverging about 55.5 Mya. Cetacea completely branched off from other artiodactyls around 50 mya. Research conducted in the late 1970s in Pakistan revealed several stages in the transition of cetaceans from land to sea. Being mammals, they surface to breathe air; they have five finger bones (even-toed) in their fins; they nurse their young; and, despite their fully aquatic life style, they retain many skeletal features from their terrestrial ungulata ancestors. The two modern parvorders of cetaceans – Mysticeti (baleen whales) and Odontoceti (toothed whales) – are thought to have separated from each other around 28–33 mya in a second cetacean radiation, the first occurring with the archaeocetes. The adaptation of animal echolocation in toothed whales distinguishes them from fully aquatic archaeocetes and early baleen whales. The presence of baleen in baleen whales occurred gradually, with earlier varieties having very little baleen, and their size is linked to baleen dependence (and subsequent increase in filter feeding).
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.