The circumventricular organs (CVOs) are small structures lining the cavities of brain ventricular system. They are associated with the semitransparent regions of the blood-brain barrier (BBB). Hence it is thought that CVOs mediate biochemical signaling and cell exchange between the brain and systemic blood. Their classification is still controversial and development not fully understood largely due to an absence of tissue-specific molecular markers. In a search for molecular determinants of CVOs we studied the green fluorescent protein (GFP) expression pattern in several zebrafish enhancer trap transgenics including Gateways (ET33-E20) that has been instrumental in defining the development of choroid plexus. In Gateways the GFP is expressed in regions of the developing brain outside the choroid plexus, which remain to be characterized. The neuroanatomical and histological analysis suggested that some previously unassigned domains of GFP expression may correspond to at least six other CVOs–the organum vasculosum laminae terminalis (OVLT), subfornical organ (SFO), paraventricular organ (PVO), pineal (epiphysis), area postrema (AP) and median eminence (ME). Two other CVOs, parapineal and subcommissural organ (SCO) were detected in other enhancer-trap transgenics. Hence enhancer-trap transgenic lines could be instrumental for developmental studies of CVOs in zebrafish and understanding of the molecular mechanism of disease such a hydrocephalus in human. Their future analysis may shed light on general and specific molecular mechanisms that regulate development of CVOs.

We developed an ex silico evolutionary-based systematic synteny approach to define and name the duplicated genes in vertebrates. The first convention for the naming of genes relied on historical precedent, the order in the human genome, and mutant phenotypes in model systems. However, total-genome duplication that resulted in teleost genomes required the naming of duplicated orthologous genes (ohnologs) in a specific manner. Unfortunately, as we review here, such naming has no defined criteria, and some ohnologs and their orthologs have suffered from incorrect nomenclature, thus creating confusion in comparative genetics and disease modeling. We sought to overcome this barrier by establishing an ex silico evolutionary-based systematic approach to naming ohnologs in teleosts. We developed software and compared gene synteny in zebrafish using the spotted gar genome as a reference, representing the unduplicated ancestral state. Using new criteria, we identified several hundred potentially misnamed ohnologs and validated the principle manually.

Kv2.1 voltage‐gated potassium channels consist of two types of α‐subunits: (a) electrically‐active Kcnb1 α‐subunits and (b) silent or modulatory α‐subunits plus β‐subunits that, similar to silent α‐subunits, also regulate electrically‐active subunits. Voltage‐gated potassium channels were traditionally viewed, mainly by electrophysiologists, as regulators of the electrical activity of the plasma membrane in excitable cells, a role that is performed by transmembrane protein domains of α‐subunits that form the electric pore. Genetic studies revealed a role for this region of α‐subunits of voltage‐gated potassium channels in human neurodevelopmental disorders, such as epileptic encephalopathy. The N‐ and C‐terminal domains of α‐subunits interact to form the cytoplasmic subunit of heterotetrameric potassium channels that regulate electric pores. Subsequent animal studies revealed the developmental functions of Kcnb1‐containing voltage‐gated potassium channels and illustrated their role during brain development and reproduction. These functions of potassium channels are discussed in this review in the context of regulatory interactions between electrically‐active and regulatory subunits.