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Emx1, Emx2 and Pax6 in specification, regionalization and arealization of the cerebral cortex
No full textThree basic aspects of cerebral cortex development — specification of cortical versus ganglionic identity, regionalization of the early cortical primordium and arealization of the developing cortex — were the main subject of our recent investigations. We previously demonstrated that the two homeobox genes Emx2 and Pax6 promote development of caudal–medial and rostral–lateral cortex, respect- ively, by properly shaping the early cortical protomap and possibly modulating the tangential growth ratio between medial and lateral cortical anlagen. More recently, by analyzing the brains of embryos bearing mutations for Emx2 and Pax6 in different combinations, we found that both genes are necessary and sufficient for a more basic developmental choice, i.e. the specification of neuroblasts in the dorsal telencephalon as cortical versus ganglionic neuroblasts. Finally, we explored the possible roles of the Emx2 paralog, Emx1, in these processes. By looking at embryos mutant for Emx1, Emx2 and Pax6 in various combinations, we did not get any evidence of Emx1 involvement in the process of cortical specification; conversely, this gene appeared to be involved to some extent in the process of regionalization of the cortical primordium along the medial–lateral axis, as a promoter of medial fates
Foxg1 confines Cajal-Retzius neuronogenesis and hippocampal morphogenesis to the dorsomedial pallium
Full text linkIt has been suggested that cerebral cortex arealization relies on positional values imparted to early cortical neuroblasts by transcription factor genes expressed within the pallial field in graded ways. Foxg1, encoding for one of these factors, previously was reported to be necessary for basal ganglia morphogenesis, proper tuning of cortical neuronal differentiation rates, and the switching of cortical neuro- blasts from early generation of primordial plexiform layer to late production of cortical plate. Being expressed along a rostral/lateral high- to-caudal/medial low gradient, Foxg1, moreover, could contribute to shaping the cortical areal profile as a repressor of caudomedial fates. We tested this prediction by a variety of approaches and found that it was correct. We found that overproduction of Cajal–Retzius neurons characterizing Foxg1/ mutants does not arise specifically from blockage of laminar histogenetic progression of neocortical neuro- blasts, as reported previously, but rather reflects lateral-to-medial repatterning of their cortical primordium. Even if lacking a neocortical plate, Foxg1/ embryos give rise to structures, which, for molecular properties and birthdating profile, are highly reminiscent of hippocampal plate and dentate blade. Remarkably, in the absence of Foxg1, additional inactivation of the medial fates promoter Emx2, although not suppressing cortical specification, conversely rescues overproduction of Reelin on neurons
Genetic control of regional identity in the developing vertebrate forebrain
No full textIn the past we isolated and characterized a number of vertebrate homeobox genes expressed in the developing brain. In particular, Emx1 and Emx2 are expressed in the developing forebrain of mouse embryos, in a region including the presumptive cerebral cortex. In the developing cerebral cortex, Emx1 is expressed in most neuroblasts and neurons at all stages of development, whereas Emx2 expression is restricted to proliferating neuroblasts of the so-called ventricular zone and to Cajal-Retzius cells, but is undetectable in most postmitotic cortical neurons. It is conceivable to hypothesize that Emx2 plays a role in the control of proliferation of cortical neuroblasts and in the regulation of their subsequent migration. This latter process has been recently analysed in some detail in null mutant mice. The expression of these and other genes has also been analysed in the developing brain of different species of vertebrates. Homologies between forebrain subdivisions have been proposed based on the conservation and divergence of gene expression patterns
Modeling human brain development with cerebral organoids
No full textThe recent discovery of a new three-dimensional culture system for the derivation of cerebral organoids from human induced pluripotent stem cells provides developmental neurobiologists with the first example of a three-dimensional framework for the study of human brain development. This innovative approach permits the in vitro assembly of a human embryonic brain rudiment that recapitulates the developing human cerebrum. Organoids contain progenitor populations that develop to yield mature cortical neuron subtypes, potentially allowing investigators to study complex brain diseases that lack appropriate animal models. © 2013 BioMed Central Ltd
Screening for infectious diseases in newly arrived asymptomatic immigrants in Southern Italy
No full textBackground: Screenings for infectious diseases in asymptomatic immigrants currently takes place when receiving new arrivals. Aims: We describe the frequency of infections in a cohort of newly arrived asymptomatic immigrants in Southern Italy. Methods: We studied a cohort of 238 Sub-Saharan African and Asian men hosted at a reception centre (CARA) in Foggia between January and December 2015. The tuberculin skin test for diagnosis of latent tuberculosis infection (LTBI) and serology/virology testing for HBV, HCV, HIV were performed. Results: From this cohort, 205 individuals agreed to be tested for serological/virological markers only, while 82 agreed to be tested for LTBI only; 49 people agreed to have both tests. Among those tested for virological markers, 23/205 (11.2%) were HBsAg positive; 12/23 (52.2%) individuals had chronic active hepatitis; 77/205 (37.6%) individuals had only anti-HBc positivity. HCV infection was present in 8/205 (3.9%) individuals, and chronic HCV infection, was diagnosed in only two people. Only 2/205 (1.0%) individuals presented with anti-HIV and HIV-RNA positivity. We found LTBI in 29.6% of TB-tested individuals. Conclusions: Asymptomatic immigrants are at increased risk for some infections, mainly HBV and tuberculosis
Angiosarcoma of the head and neck with intra-oral presentation. A clinico-pathological study of 4 cases
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