A monoclonal antibody stains radial glia in the adult zebrafish (Danio rerio) CNS

We have prepared a monoclonal antibody, denoted as C-4, which specifically recognizes astroglia with radial forms in the adult zebrafish brain. This report suggests that there are at least two different types of astroglia in the mature teleost brain, only one of which is recognized by C-4. Further, we have found that the C-4-binding astroglia are comprised of three morphologically distinct cellular types. Immunoblot analysis revealed that the antibody recognized only one protein band of approximately 30 kDa in the membrane fraction of the adult zebrafish brain. In the spinal cord, stained glial cells appeared to occur in the same location as ependymocytes. The processes and cell bodies of extra-ependymal cells, many adjacent to ependymocytes and a few near the pial surface, were also stained by the antibody. In the cerebellum, long processes stained by C-4 were found in the molecular layer, and these connected the cerebellum surface to the Purkinje-like cell layer. Long processes were also stained in the mesencephalon, but these were thicker than those in the spinal cord and they linked the two ventricles. The optic tectum, olfactory bulb and cranial nerves, including the optic nerves, were, however, completely devoid of the C-4 antigen. Double-immunofluorescence with antibodies against glial fibrillary acidic protein (GFAP) and C-4 demonstrated that C-4-positive cells were also GFAP-positive, although there was also a subset of GFAP-positive cells which were C-4-negative. The C-4 antibody is thus a useful tool for studying subtypes of GFAP-positive astroglia.     

Peripheral glia direct axon guidance across the CNS/PNS transition zone.

CNS glia have integral roles in directing axon migration of both vertebrates and insects. In contrast, very little is known about the roles of PNS glia in axonal pathfinding. In vertebrates and Drosophila, anatomical evidence shows that peripheral glia prefigure the transition zones through which axons migrate into and out of the CNS. Therefore, peripheral glia could guide axons at the transition zone. We used the Drosophila model system to test this hypothesis by ablating peripheral glia early in embryonic neurodevelopment via targeted overexpression of cell death genes grim and ced-3. The effects of peripheral glial loss on sensory and motor neuron development were analyzed. Motor axons initially exit the CNS in abnormal patterns in the absence of peripheral glia. However, they must use other cues within the periphery to find their correct target muscles since early pathfinding errors are largely overcome. When peripheral glia are lost, sensory axons show disrupted migration as they travel centrally. This is not a result of motor neuron defects, as determined by motor/sensory double-labeling experiments. We conclude that peripheral glia prefigure the CNS/PNS transition zone and guide axons as they traverse this region.     

Is it possible to distinguish alien species of beetles (Coleoptera) from native ones?

Species established outside their native ranges are termed alien. Biological invasions of beetles are poorly studied. Distinguishing between alien and native species is necessary for conservation as well as for taxonomic, zoogeographic, and evolutionary studies. It constitutes a difficult problem, but the experience of botany and some branches of zoology gives reasons to believe that it is not unsolvable. The following criteria for distinguishing alien beetle species from native ones are proposed based on the criteria developed for plants, algae, mammals, and marine invertebrates: (1) detection of an established population of the species which has not been recorded earlier in the region; (2) disjunction of the range which cannot be explained by disjunction of suitable landscapes or host plant ranges; (3) expansion of a part of the range isolated from its main part; (4) highly localized distribution in an area adjacent to a known invasion pathway; (5) establishment in other regions; (6) dependency on another non-native species (feeding on an alien host plant or animal); (7) absence of specific parasites in the given region and their presence in some other region; (8) association with anthropogenic biotopes; (9) sharp fluctuations of abundance; (10) lack of taxonomically close species in the given region and their presence in other regions; (11) detection in the region of two or more taxonomically and/or ecologically close species typical of another region; (12) presence of known vectors of invasion; (13) low genetic diversity; (14) reproduction by parthenogenesis or inbreeding. These criteria are mere indirect evidences of the alien status of a species in the given territory, because numerous exceptions exist. Usually it is impossible to recognize an alien species by a single criterion, but matching several criteria characterizes the species as an alien one with high probability.     

Generation of functional neurons and glia from multipotent adult mouse germ-line stem cells

Recently, we reported the successful establishment of multipotent adult germ-line stem cells (maGSCs) from cultured adult mouse spermatogonial stem cells. Similar to embryonic stem cells, maGSCs are able to self-renew and differentiate into derivatives of all three germ layers. These properties make maGSCs a potential cell source for the treatment of neural degenerative diseases. In this study, we describe the generation of maGSC-derived proliferating neural precursor cells using growth factor-mediated neural lineage induction. The neural precursors were positive for nestin and Sox1 and could be continuously expanded. Upon further differentiation, they formed functional neurons and glial cells, as demonstrated by expression of lineage-restricted genes and proteins and by electrophysiological properties. Characterization of maGSC-derived neurons revealed the generation of specific subtypes, including GABAergic, glutamatergic, serotonergic, and dopaminergic neurons. Electrophysiological analysis revealed passive and active membrane properties and postsynaptic currents, indicating their functional maturation. Functional networks formed at later stages of differentiation, as evidenced by synaptic transmission of spontaneous neuronal activity. In conclusion, our data demonstrate that maGSCs may be used as a new stem cell source for basic research and biomedical applications.     

Oligodendrocytes and radial glia derived from adult rat spinal cord progenitors: morphological and immunocytochemical characterization.

Self-renewing, multipotent neural progenitor cells (NPCs) reside in the adult mammalian spinal cord ependymal region. The current study characterized, in vitro, the native differentiation potential of spinal cord NPCs isolated from adult enhanced green fluorescence protein rats. Neurospheres were differentiated, immunocytochemistry (ICC) was performed, and the positive cells were counted as a percentage of Hoescht+ nuclei in 10 random fields. Oligodendrocytes constituted most of the NPC progeny (58.0% of differentiated cells; 23.4% in undifferentiated spheres). ICC and electron microscopy (EM) showed intense myelin production by neurospheres and progeny. The number of differentiated astrocytes was 18.0%, but only 2.8% in undifferentiated spheres. The number of differentiated neurons was 7.4%, but only 0.85% in undifferentiated spheres. The number of differentiated radial glia (RG) was 73.0% and in undifferentiated spheres 80.9%. EM showed an in vitro phagocytic capability of NPCs. The number of undifferentiated NPCs was 32.8% under differentiation conditions and 78.9% in undifferentiated spheres. Compared with ependymal region spheres, the spheres derived from the peripheral white matter of the spinal cord produced glial-restricted precursors. These findings indicate that adult rat spinal cord ependymal NPCs differentiate preferentially into oligodendrocytes and RG, which may support axonal regeneration in future trials of transplant therapy for spinal cord injury.     

Pragmatic criteria to distinguish psychrophiles and psychrotrophs in ecological systems.

Optimal incubation times and temperatures were determined for populations of psychrophilic and psychrotrophic bacteria from a seasonally cold ocean. The application of conventional pragmatic criteria did not differentiate the two populations, although they could be distinguished by growth at two temperatures.     

Cardiac regenerative potential of cardiosphere‐derived cells from adult dog hearts

The regenerative potential of cardiosphere‐derived cells (CDCs) for ischaemic heart disease has been demonstrated in mice, rats, pigs and a recently completed clinical trial. The regenerative potential of CDCs from dog hearts has yet to be tested. Here, we show that canine CDCs can be produced from adult dog hearts. These cells display similar phenotypes in comparison to previously studied CDCs derived from rodents and human beings. Canine CDCs can differentiate into cardiomyocytes, smooth muscle cells and endothelial cells in vitro. In addition, conditioned media from canine CDCs promote angiogenesis but inhibit cardiomyocyte death. In a doxorubicin‐induced mouse model of dilated cardiomyopathy (DCM), intravenous infusion of canine CDCs improves cardiac function and decreases cardiac fibrosis. Histology revealed that injected canine CDCs engraft in the mouse heart and increase capillary density. Out study demonstrates the regenerative potential of canine CDCs in a mouse model of DCM.     

CNS development: The obscure origins of adult stem cells.

Stem cells of the adult central nervous system are the focus of a great deal of attention because of their potential for making new neural cells. A recent study has claimed to identify their in vivo location, but this important issue remains controversial.     

3‐acetylpyridine‐induced degeneration in the adult ascidian neural complex: Reactive and regenerative changes in glia and blood cells

Ascidians are interesting neurobiological models because of their evolutionary position as a sister‐group of vertebrates and the high regenerative capacity of their central nervous system (CNS). We investigated the degeneration and regeneration of the cerebral ganglion complex of the ascidian Styela plicata following injection of the niacinamide antagonist 3‐acetylpyridine (3AP), described as targeting the CNS of several vertebrates. For the analysis and establishment of a new model in ascidians, the ganglion complex was dissected and prepared for transmission electron microscopy (TEM), routine light microscopy (LM), immunohistochemistry and Western blotting, 1 or 10 days after injection of 3AP. The siphon stimulation test (SST) was used to quantify the functional response. One day after the injection of 3AP, CNS degeneration and recruitment of a non‐neural cell type to the site of injury was observed by both TEM and LM. Furthermore, weaker immunohistochemical reactions for astrocytic glial fibrillary acidic protein (GFAP) and neuronal βIII‐tubulin were observed. In contrast, the expression of caspase‐3, a protein involved in the apoptotic pathway, and the glycoprotein CD34, a marker for hematopoietic stem cells, increased. Ten days after the injection of 3AP, the expression of markers tended toward the original condition. The SST revealed attenuation and subsequent recovery of the reflexes from 1 to 10 days after 3AP. Therefore, we have developed a new method to study ascidian neural degeneration and regeneration, and identified the decreased expression of GFAP and recruitment of blood stem cells to the damaged ganglion as reasons for the success of neuroregeneration in ascidians. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 75: 877–893, 2015     

Influence of adult Schwann cells and olfactory ensheathing glia on axon--target cell interactions in the CNS: a comparative analysis using a retinotectal co-graft model

We used an in vivo transplant approach to examine how adult Schwann cells and olfactory ensheathing glia OEG influence the specificity of axon-target cell interactions when they are introduced into the CNS. Populations of either Schwann cells or OEG were mixed with dissociated fetal tectal cells presumptive superior colliculus and, after reaggregation, pieces were grafted onto newborn rat superior colliculus. Both glial types were prelabeled with lentiviral vectors encoding green fluorescent protein. Grafts rapidly established fiber connections with the host and retinal projections into co-grafts were assessed 656 days posttransplantation by injecting cholera toxin B into host eyes. In control rats that received pure dissociated-reaggregated tectal grafts, retinal ganglion cell RGC axons selectively innervated defined target areas, corresponding to the retinorecipient layer in normal superior colliculus. The pattern of RGC axon ingrowth into OEG containing co-grafts was similar to that in control grafts. However, in Schwann cell co-grafts there was reduced host retinal input into presumptive target areas and many RGC axons were scattered throughout the neuropil. Given that OEG in co-grafts had minimal impact on axon-target cell recognition, OEG might be an appropriate cell type for direct transplantation into injured neuropil when attempting to stimulate specific pathway reconstruction.     

Neurogenesis in adult CNS: from denial to opportunities and challenges for therapy

The discovery of neurogenesis and neural stem cells (NSC) in the adult CNS has overturned a long-standing and deep-routed "dogma" in neuroscience, established at the beginning of the 20(th) century. This dogma lasted for almost 90 years and died hard when NSC were finally isolated from the adult mouse brain. The scepticism in accepting adult neurogenesis has now turned into a rush to find applications to alleviate or cure the devastating diseases that affect the CNS. Here we highlight a number of methodological, technical and conceptual drawbacks responsible for the historical denial of adult neurogenesis. Furthermore, we discuss old and new issues that need to be faced before NSC or endogenous neurogenesis can safely enter into the doctor's bag for therapies.     

Characterization of a plasma membrane protein present in non-myelin-forming PNS and CNS glia,a subpopulation of PNS neurons,perineurial cells and smooth muscle in adult rats

Summary A plasma membrane protein common to nonmyelin-forming peripheral glia, including non-myelin-forming Schwann cells, satellite cells and enteric glia, is recognized and defined by monoclonal antibody A5E3. It is not detectable immunohistochemically on myelin-forming Schwann cells. The antigen is also present in large amounts on smooth muscle cells and perineurial cells, on some PNS neurons, and at lower levels on astrocytes of adult rat. In neonatal but not adult animals, the antigen is present on skeletal muscle fibres and myoblasts. In immunoblots and immune precipitation experiments on smooth muscle and Schwann cell extracts the antigen is a polypeptide with an apparent molecular weight of 130 kd. In being present in some non-neural tissues, albeit very highly restricted in cell type, this antigen resembles several other cell surface glycoproteins found in large amounts in the nervous system.     

Degenerative and regenerative responses of injured neurons in the central nervous system of adult mammals.

In adult mammals, the severing of the optic nerve near the eye is followed by a loss of retinal ganglion cells (RGCs) and a failure of axons to regrow into the brain. Experimental manipulations of the non-neuronal environment of injured RGCs enhance neuronal survival and make possible a lengthy axonal regeneration that restores functional connections with the superior colliculus. These effects suggest that injured nerve cells in the mature central nervous system (CNS) are strongly influenced by interactions with components of their immediate environment as well as their targets. Under these conditions, injured CNS neurons can express capacities for growth and differentiation that resemble those of normally developing neurons. An understanding of this regeneration in the context of the cellular and molecular events that influence the interactions of axonal growth cones with their non-neuronal substrates and neuronal targets should help in the further elucidation of the capacities of neuronal systems to recover from injury.     

Glial progenitors of the neonatal subventricular zone differentiate asynchronously, leading to spatial dispersion of glial clones and to the persistence of immature glia in the adult mammalian CNS

The subventricular zone (SVZ) of the developing mammalian forebrain gives rise to astrocytes and oligodendrocytes in the neocortex and white matter, and neurons in the olfactory bulb in perinatal life. We have examined the developmental fates and spatial distributions of the descendants of single SVZ cells by infecting them in vivo at postnatal day 0-1 (P0-1) with a retroviral "library". In most cases, individual SVZ cells gave rise to either oligodendrocytes or astrocytes, but some generated both types of glia. Members of glial clones can disperse widely through the gray and white matter. Progenitors continued to divide after stopping migration, generating clusters of related cells. However, the progeny of a single SVZ cell does not differentiate synchronously: individual clones contained both mature and less mature glia after short or long intervals. For example, progenitors that settled in the white matter generated three types of clonal oligodendrocyte clusters: those composed of only myelinating oligodendrocytes, of both myelinating oligodendrocytes and non-myelinating oligodendrocytes, or of only non-myelinating cells of the oligodendrocyte lineage. Thus, some progenitors do not fully differentiate, but remain immature and may continue to cycle well into adult life.