Role of intracortical neuropil growth in the gyrification of the primate cerebral cortex.

The convolutions of the mammalian cerebral cortex allow the enlargement of its surface and addition of novel functional areas during evolution while minimizing expansion of the cranium. Cognitive neurodevelopmental disorders in humans, including microcephaly and lissencephaly, are often associated with impaired gyrification. In the classical model of gyrification, surface area is initially set by the number of radial units, and the forces driving cortical folding include neuronal growth, formation of neuropil, glial cell intercalation, and the patterned growth of subcortical white matter.

Variation of Human Neural Stem Cells Generating Organizer States In Vitro before Committing to Cortical Excitatory or Inhibitory Neuronal Fates.

Better understanding of the progression of neural stem cells (NSCs) in the developing cerebral cortex is important for modeling neurogenesis and defining the pathogenesis of neuropsychiatric disorders. Here, we use RNA sequencing, cell imaging, and lineage tracing of mouse and human in vitro NSCs and monkey brain sections to model the generation of cortical neuronal fates. We show that conserved signaling mechanisms regulate the acute transition from proliferative NSCs to committed glutamatergic excitatory neurons.

Gliogenesis in the outer subventricular zone promotes enlargement and gyrification of the primate cerebrum.

The primate cerebrum is characterized by a large expansion of cortical surface area, the formation of convolutions, and extraordinarily voluminous subcortical white matter. It was recently proposed that this expansion is primarily driven by increased production of superficial neurons in the dramatically enlarged outer subventricular zone (oSVZ). Here, we examined the development of the parietal cerebrum in macaque monkey and found that, indeed, the oSVZ initially adds neurons to the superficial layers II and III, increasing their thickness.

Metabolic regulation and glucose sensitivity of cortical radial glial cells.

The primary stem cells of the cerebral cortex are the radial glial cells (RGCs), and disturbances in their operation lead to myriad brain disorders in all mammals from mice to humans. Here, we found in mice that maternal gestational obesity and hyperglycemia can impair the maturation of RGC fibers and delay cortical neurogenesis. To investigate potential mechanisms, we used optogenetic live-imaging approaches in embryonic cortical slices.

Bidirectional radial Ca(2+) activity regulates neurogenesis and migration during early cortical column formation.

Cortical columns are basic cellular and functional units of the cerebral cortex that are malformed in many brain disorders, but how they initially develop is not well understood. Using an optogenetic sensor in the mouse embryonic forebrain, we demonstrate that Ca(2+) fluxes propagate bidirectionally within the elongated fibers of radial glial cells (RGCs), providing a novel communication mechanism linking the proliferative and postmitotic zones before the onset of synaptogenesis. Our results indicate that Ca(2+) activity along RGC fibers provides feedback information along the radial migratory pathway, influencing neurogenesis and migration during early column development.

Cortical gyrification induced by fibroblast growth factor 2 in the mouse brain.

Gyrification allows an expanded cortex with greater functionality to fit into a smaller cranium. However, the mechanisms of gyrus formation have been elusive. We show that ventricular injection of FGF2 protein at embryonic day 11.

FGF signaling expands embryonic cortical surface area by regulating Notch-dependent neurogenesis.

The processes regulating cortical surface area expansion during development and evolution are unknown. We show that loss of function of all fibroblast growth factor receptors (FgfRs) expressed at the earliest stages of cortical development causes severe deficits in surface area growth by embryonic day 12.5 (E12.

Actinomyces naturae sp. nov., the first Actinomyces sp. isolated from a non-human or animal source.

Three facultatively anaerobic, Gram-positive staining, rod-shaped, non-spore forming, flagellated bacterial strains, BL-75, BL-79(T) and BL-104, were isolated from chlorinated solvent-contaminated groundwater. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed them to represent a distinct lineage within the genus Actinomyces with sequence identities in the range of <88-95.4% with previously described Actinomyces species.

Shh and Gli3 regulate formation of the telencephalic-diencephalic junction and suppress an isthmus-like signaling source in the forebrain.

In human holoprosencephaly (HPE), the forebrain does not separate fully into two hemispheres. Further, the border between the telencephalon and diencephalon, the telencephalic/diencephalic junction (TDJ), is often indistinct, and the ventricular system can be blocked at the third ventricle, creating a forebrain 'holosphere'. Mice deficient in Sonic Hedgehog (Shh) have previously been described to show HPE and associated cyclopia.

Neural stem cell regulation, fibroblast growth factors, and the developmental origins of neuropsychiatric disorders.

There is increasing appreciation for the neurodevelopmental underpinnings of many psychiatric disorders. Disorders that begin in childhood such as autism, language disorders or mental retardation as well as adult-onset mental disorders may have origins early in neurodevelopment. Neural stem cells (NSCs) can be defined as self-renewing, multipotent cells that are present in both the embryonic and adult brain.

Detection and quantification of Dehalogenimonas and "Dehalococcoides" populations via PCR-based protocols targeting 16S rRNA genes.

Members of the haloalkane dechlorinating genus Dehalogenimonas are distantly related to "Dehalococcoides" but share high homology in some variable regions of their 16S rRNA gene sequences. In this study, primers and PCR protocols intended to uniquely target Dehalococcoides were reevaluated, and primers and PCR protocols intended to uniquely target Dehalogenimonas were developed and tested. Use of the genus-specific primers revealed the presence of both bacterial groups in groundwater at a Louisiana Superfund site.

Patterning the dorsal telencephalon: a role for sonic hedgehog?

Division of the telencephalic vesicle into hemispheres and specification of the cerebral cortex are key stages in forebrain development. We investigate the interplay in these processes of Sonic hedgehog (Shh), fibroblast growth factors (Fgfs), and the transcription factor Gli3, which in its repressor form (Gli3R) antagonizes Shh signaling and downregulates expression of several Fgf genes. Contrary to previous reports, Shh is not required for dorsal hemisphere separation.

Description of Azospira restricta sp. nov., a nitrogen-fixing bacterium isolated from groundwater.

A novel, Gram-negative bacterial strain, SUA2(T), isolated from groundwater, was characterized using a polyphasic approach. Cells are Gram-negative, non-spore-forming, straight to curved rods with a single polar flagellum. Strain SUA2(T) is oxidase- and catalase-positive and is able to fix nitrogen.

Bacterial diversity of an acidic Louisiana groundwater contaminated by dense nonaqueous-phase liquid containing chloroethanes and other solvents.

Bacterial concentration and diversity was assessed in a moderately acidic (pH 5.1) anaerobic groundwater contaminated by chlorosolvent-containing DNAPL at a Superfund site located near Baton Rouge, Louisiana. Groundwater analysis revealed a total aqueous-phase chlorosolvent concentration exceeding 1000 mg L(-1), including chloroethanes, vinyl chloride, 1,2-dichloropropane, and hexachloro-1,3-butadiene as the primary contaminants.

Area and layer patterning in the developing cerebral cortex.

Two anatomical patterns characterize the neocortex, and both are essential for normal cortical function. First, neocortex is divided into anatomically distinct and functionally specialized areas that form a species-specific map. Second, neocortex is composed of layers that organize cortical connectivity.

Extensive diversity of ionizing-radiation-resistant bacteria recovered from Sonoran Desert soil and description of nine new species of the genus Deinococcus obtained from a single soil sample.

The ionizing-radiation-resistant fractions of two soil bacterial communities were investigated by exposing an arid soil from the Sonoran Desert and a nonarid soil from a Louisiana forest to various doses of ionizing radiation using a (60)Co source. The numbers of surviving bacteria decreased as the dose of gamma radiation to which the soils were exposed increased. Bacterial isolates surviving doses of 30 kGy were recovered from the Sonoran Desert soil, while no isolates were recovered from the nonarid forest soil after exposure to doses greater than 13 kGy.