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Odontogenic Epithelium and its Residues
Published in Roger M. Browne, Investigative Pathology of the Odontogenic Cysts, 2019
The two major classes of proteins described in the extracellular matrix of enamel from most mammalian species studied are the hydrophobic proline-, glutamine-, and histidine-rich amelogenins and the acidic serine-, glycine-, and aspartic-rich enamelins. During the secretory stage of amelogenesis in rodents and man, both the enamelins and amelogenins are secreted with the latter class of proteins constituting the major proportion of the matrix. Maturation is characterized by selective loss of amelogenins resulting in an apparent increase in enamelin concentration in the tissues. Finally, with increasing mineralization, the lower molecular weight degradation products of both classes of protein predominate.61,76 The situation in rabbit may be less complicated as it has been proposed that only enamelins are present in the developing enamel matrix.76,77 Biochemical and immunological studies in this area are thus complicated by the constantly changing proportions of amelogenins and enamelins, species differences, together with the apparent great diversity of molecular species within each family of molecules. The current situation is further complicated by recent suggestions, based on sequence homology studies, that some of the extracellular matrix proteins of enamel are related to serum albumin.78
Molecular Biology of the Amelogenin Gene
Published in Colin Robinson, Jennifer Kirkham, Roger Shore, Dental Enamel, 2017
James P. Simmer, Malcolm L. Snead
The exact role of extracellular matrix proteins in controlling the synthesis of tooth enamel remains unclear. Much work has been carried out on the amelogenins, the most abundant proteins found in the developing enamel, which are secreted by the ameloblasts. Analysis of the amino acid sequences of amelogenins of several different animal species confirms that these are highly conserved. This extensive conservation implies a fundamental role in the development of enamel in each of these species. It is not yet known, however, if these species-specific differences affect the morphology of the mature enamel crystals. There has been considerable interest in the amelogenin gene. In part, this is due to the sexual dimorphism demonstrated in species where the gene exists on both the X- and Y-chromosomes. Additional diversity is generated by a mechanism of alternative RNA splice site selection whereby a number of different amelogenin isoforms are generated. It has been suggested that the expression of these different alternatively spliced amelogenins may be developmentally regulated and that each different isoform may have a specific role in tooth enamel formation. By using the techniques of molecular biology it has been possible to gain an insight into the structure and expression of the amelogenins. Although there is still much to learn about the molecular biology of the amelogenin gene and its products, it is important that we widen our studies to include the nonamelogenin enamel proteins to obtain a more complete picture of enamel formation.
Genetic variation and differentiation among a native British and five migrant South Asian populations of the East Midlands (UK) based on CODIS forensic STR loci
Published in Annals of Human Biology, 2020
Ella Jane Brearley, Puneetpal Singh, Jasvinder Singh Bhatti, Sarabjit Mastana
The original FBI Combined DNA Index System (CODIS) nationwide DNA database focussed on the analysis of 13 STR loci. These are commonly utilised for human identity testing both in forensic casework and paternity, mainly due to availability within many commercial human identification kits (Butler 2006). The CODIS loci contained in AmpFISTR® Profiler PlusTM and AmpFISTR® COfilerTM kits (Applied Biosystems, Foster City, CA, USA) included the autosomal tetranucleotide loci D3S1358, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, D16S539, vWA, TPOX, FGA, CSF1PO and TH01. The Amelogenin locus is also included in these kits for sex/gender identification. These loci (except D5S818 and CSF1PO) are located on different chromosomes, therefore are independently inherited. These loci are non-coding, disease-free markers used solely for forensic applications.
Persistent Wnt/β-catenin signaling in mouse epithelium induces the ectopic Dspp expression in cheek mesenchyme
Published in Organogenesis, 2019
Nan Zhou, Nan Li, Jing Liu, Yu Wang, Jun Gao, Yingzhang Wu, Xiaoyan Chen, Chao Liu, Jing Xiao
Our study showed the premature and ectopic Dspp expression in the K14-cre; Ctnnb1ex3f oral and cheek mesenchyme, suggesting the promotion of epithelial Wnt/β-catenin signaling on odontoblast differentiation. On the other hand, the expression of Amelogenin was diminished in the E17.5 K14-cre; Ctnnb1ex3f oral epithelium, suggesting the inhibitory effect on ameloblast differentiation. Even in the ectopic Dspp-expressing location, the K14-cre; Ctnnb1ex3f cheek epithelial cells overlying the dentin-like layer and Dspp-expressing mesenchymal cells were devoid of Amelogenin expression and not elongated. Moreover, we have to mention that when recombined with the mesenchyme from the E13.5 WT molar germs or the E10.5 2nd branchial arch, both the E10.5 and E13.5 K14-cre; Ctnnb1ex3f oral epithelium failed to form tooth (our unpublished data). The rapid keratinization of the K14-cre; Ctnnb1ex3f oral epithelium was though to account for the failure of tooth formation in the tissue recombination experiments. Additionally, the opposing effects of epithelial Wnt/β-catenin signaling on oral epithelium and mesenchyme were also observed in cell proliferation. Compared with the WT control, the cell proliferation was more active in the K14-cre; Ctnnb1ex3f oral mesenchyme, but almost dormant in the K14-cre; Ctnnb1ex3f oral epithelium.
Non-invasive prenatal diagnosis of foetal gender through maternal circulation in first trimester of pregnancy
Published in Journal of Obstetrics and Gynaecology, 2019
Saeed Mahdavi, Fatemeh Karami, Saeed Sabbaghi
Determining the foetal gender is highly important in X-linked genetic diseases families wherein the carrier unaffected mother has 50% chance to have affected son. Most of those diseases such as haemophilia and Duchenne Muscular Dystrophy (DMD) are associated with early death of affected males along with sometimes highly expensive current supportive, but not definite treatment plans. In these cases, foetal sex determination in early weeks of pregnancy can help to decrease overall costs of further specific genetic tests in female foetuses whom will be determined at least as carrier (Wright et al. 2012). There are many different reports which have implicated various techniques to determine the foetal gender in the first trimester of pregnancy. Primary approaches were based on karyotpe analysis or polymerase chain reaction (PCR) of some sex chromosome-specific genes as well as amelogenin gene (AMEL) on obtained CVS samples (Wilson 2005; Wright et al. 2012). Novel non-invasive sex determination methods based on cffDNA testing include using of various platforms of next generation sequencing (NGS), methylation and real-time PCR amplification of Y-chromosome specific genes (Zimmermann et al. 2007; Della Ragione et al. 2010; Wang et al. 2017; Zhu et al. 2017). Although all of the aforementioned techniques have shown reliable accuracy in detection of foetal gender, real-time PCR analysis seems to be frequently used as reference method when there is no concern about other genetic abnormalities. There are many reports which have used of real-time PCR amplification tests on different male specific gene panels to determine foetal sex through maternal circulation.