Journal of Comparative Neurology

The subdivisions of the alar hypothalamus in the developing Xenopus laevis are characterized by their distinct expression patterns of regulatory genes and neuronal markers, together with hodological features. The supraoptoparaventricular (dorsal) and the suprachiasmatic (ventral) regions, both subdivided into rostral and caudal portions, form the alar hypothalamus, a component of the secondary prosencephalon. Its boundaries are established caudally with the diencephalic prethalamic eminence and prethalamus, dorsally with the preoptic region, and ventrally with the basal hypothalamus.

The connective tissue of the brain (meninges) and of the nerves has been described in vertebrates, but not in invertebrates. In five copepod species, these areas have networks of cells with ultrastructural characteristics and organization (diagram of perikarya and processes on left) paralleling those of meningeal/connective tissue cells (right).These findings are important in the context of the possible role of meninges as an organizer of neural tissue morphogenesis, of neural stem cell fate decision and neural functional plasticity.

The midbrain periaqueductal gray (PAG) plays a central role in the descending control of vocalization across vertebrates, including teleost fish. Here, we demonstrate extensive bidirectional connectivity between the PAG and a number of known auditory areas (black) and vocal-motor structures (red) in the brain of a vocal fish, the plainfin midshipman. Our findings support the hypothesis that the teleost PAG is centrally involved in auditory-vocal integration and reveal the anatomical network engaged in this integration.

The projections from the parvocelluar layers lateral geniculate nucleus (LGN P) are capable of driving to the primary visual cortex (V1). These connections have large presynaptic swellings (boutons) that express vesicular glutamate transporter 2 (Vglut2) and parvalbumnin (PV). We examined the possible driving projections to V2, namely, those from V1 and pulvinar. Our findings indicate that, among the possible driving projections to V2, the pulvinar projection is more similar to LGN P projections and hence more likely to drive V2.

Three lines of eGFP-expressing mice were used for FACS isolating sustentacular cells, Sox2-expressing globose basal cells (GBCs), Neurog1-expressing GBCs, and OMP-expressing neurons from adult olfactory epithelium. Distinct, but overlapping gene expression profiles characterized each set of isolates. Among the differentially expressed genes were members of the coREST complex, a histone modifier. The data illuminate and help explicate the transitions as cells progress along the neurogenic path from stem cell to fully mature olfactory sensory neuron.

The BRAG family of Arf-GEFs exhibits distinct synaptic localization in the mouse retina.

In both mouse and guinea pig corneal epithelium, calcitonin gene-related peptide immunoreactive (CGRP-IR) nerve terminals, which are likely to be nociceptive, are predominantly simple. In contrast, transient receptor potential subfamily M member 8 channel immunoreactive (TRPM8-IR) nerve terminals, which are likely to be cold receptive, are highly branched and complex. The findings suggest that corneal sensory nerve terminals with different modalities can be defined by their neurochemistry and morphology.

The main finding of our study is that there is a highly significant reduction of calbindin in the dorsal thalamus of male Fmr1 KO mice when compared to females or WT controls whereas calretinin and parvalbumin expression were not affected in Fmr1 KO mice. The downregulation of calbindin is especially important in midline/intralaminar nuclei and posterior thalamic nuclei (up to 67% reduction).

Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and are capable of direct photoreception. These ipRGCs are involved in non-visual functions like circadian, pupillary and endocrine responses to light. By using immunohistochemistry with antibodies directed against proteins typically expressed in retinal ganglion cells, we describe here the expression pattern in melanopsin-positive ipRGCs. The majority of ipRGC types expressed Isl-1, MAP2, γ-Synuclein and NeuN, whereas Brn3 transcription factor and different neurofilaments were able to discriminate between ipRGC subtypes.

Kisspeptins are now considered as major actors in the neuroendocrine control of puberty and reproduction, at least in mammals. Most teleost fishes have two kiss genes, kiss1 and kiss2, but their respective functions in reproduction are still unclear. Thus, it is important to study the distribution of kiss1 and kiss2 expressing cells in the brain and to see which populations are subject to change in expression over the sex cycle. In the European sea bass, an economically important fish, we show that kiss1 expressing cells in the mediobasal hypothalamus show clear changes in expression in mature males and females. These data suggest a role for Kiss1 in reproduction of the sea bass. In addition, kiss1 mRNAs were expressed in FSHβ positive cells and never in LHβ positive cells of the pituitary level.

Cannabinoid receptor 1 is expressed in the brain of all vertebrates. We cloned AptCB1R of the weakly electric fish, Apteronotus leptorhynchus and used in situ hybridization to localize its expression. AptCB1R transcripts were highly expressed in the telencephalon within both subpallium and pallium. In subpallium, strong expression was seen within cells of a striatal region. In the pallium expression was strong with the dorsocentral (DC) and rostral dorsomedial/lateral region. We discuss the functional and evolutionary implications of this localization.