Gsx2, but not Gsx1, is necessary for early forebrain patterning and long-term survival in zebrafish.

BACKGROUND: Homeobox transcription factor encoding genes, genomic screen homeobox 1 and 2 (gsx1 and gsx2), are expressed during neurodevelopment in multiple vertebrates. However, we have limited knowledge of the dynamic expression of these genes through developmental time and the gene networks that they regulate in zebrafish. RESULTS: We confirmed that gsx1 is expressed initially in the hindbrain and diencephalon and later in the optic tectum, pretectum, and cerebellar plate. gsx2 is expressed in the early telencephalon and later in the pallium and olfactory bulb. gsx1 and gsx2 are co-expressed in the hypothalamus, preoptic area, and hindbrain, however, rarely co-localize in the same cells. gsx1 and gsx2 mutant zebrafish were made with TALENs. gsx1 mutants exhibit stunted growth, however, they survive to adulthood and are fertile. gsx2 mutants experience swim bladder inflation failure that prevents survival. We also observed significantly reduced expression of multiple forebrain patterning distal-less homeobox genes in mutants, and expression of foxp2 was not significantly affected. CONCLUSIONS: This work provides novel tools with which other target genes and functions of Gsx1 and Gsx2 can be characterized across the central nervous system to better understand the unique and overlapping roles of these highly conserved transcription factors.

A Mouse Holder for Awake Functional Imaging in Unanesthetized Mice: Applications in 31P Spectroscopy, Manganese-Enhanced Magnetic Resonance Imaging Studies, and Resting-State Functional Magnetic Resonance Imaging.

Anesthesia is often used in preclinical imaging studies that incorporate mouse or rat models. However, multiple reports indicate that anesthesia has significant physiological impacts. Thus, there has been great interest in performing imaging studies in awake, unanesthetized animals to obtain accurate results without the confounding physiological effects of anesthesia. Here, we describe a newly designed mouse holder that is interfaceable with existing MRI systems and enables awake in vivo mouse imaging. This holder significantly reduces head movement of the awake animal compared to previously designed holders and allows for the acquisition of improved anatomical images. In addition to applications in anatomical T2-weighted magnetic resonance imaging (MRI), we also describe applications in acquiring 31P spectra, manganese-enhanced magnetic resonance imaging (MEMRI) transport rates and resting-state functional magnetic resonance imaging (rs-fMRI) in awake animals and describe a successful conditioning paradigm for awake imaging. These data demonstrate significant differences in 31P spectra, MEMRI transport rates, and rs-fMRI connectivity between anesthetized and awake animals, emphasizing the importance of performing functional studies in unanesthetized animals. Furthermore, these studies demonstrate that the mouse holder presented here is easy to construct and use, compatible with standard Bruker systems for mouse imaging, and provides rigorous results in awake mice.