Biology subjects

Kozol, R. A.

Publications and source records attributed to Kozol, R. A..

3 recordsLinked to original sources

bioRxiv2023

Context-dependent hyperactivity in syngap1a and syngap1b zebrafish autism models.

Background and AimsSYNGAP1 disorder is a prevalent genetic form of Autism Spectrum Disorder and Intellectual Disability (ASD/ID) and is caused by de novo or inherited mutations in one copy of the SYNGAP1 gene. In addition to ASD/ID, SYNGAP1 disorder is associated with comorbid symptoms including treatment-resistant-epilepsy, sleep disturbances, and gastrointestinal distress. Mechanistic links between these diverse symptoms and SYNGAP1 variants remain obscure, therefore, our goal was to generate a zebrafish model in which this range of symptoms can be studied. MethodsWe used CRISPR/Cas9 to introduce frameshift mutations in the syngap1a and syngap1b zebrafish duplicates (syngap1ab) and validated these stable models for Syngap1 loss-of-function. Because SYNGAP1 is extensively spliced, we mapped splice variants to the two zebrafish syngap1a and b genes and identified mammalian-like isoforms. We then quantified locomotory behaviors in zebrafish syngap1ab larvae under three conditions that normally evoke different arousal states in wild type larvae: aversive, high-arousal acoustic, medium-arousal dark, and low-arousal light stimuli. ResultsWe show that CRISPR/Cas9 indels in zebrafish syngap1a and syngap1b produced loss-of-function alleles at RNA and protein levels. Our analyses of zebrafish Syngap1 isoforms showed that, as in mammals, zebrafish Syngap1 N- and C-termini are extensively spliced. We identified a zebrafish syngap1 1-like variant that maps exclusively to the syngap1b gene. Quantifying locomotor behaviors showed that syngap1ab larvae are hyperactive compared to wild type but to differing degrees depending on the stimulus. Hyperactivity was most pronounced in low arousal settings, with overall movement increasing with the number of mutant syngap1 alleles. ConclusionsOur data support mutations in zebrafish syngap1ab as causal for hyperactivity associated with elevated arousal that is especially pronounced in low-arousal environments.

neuroscience↗

bioRxiv2022

Novel husbandry practices result in rapid rates of growth and sexual maturation without impacting adult behavior in the blind Mexican cavefish.

The development of animal model systems is dependent on the standardization of husbandry protocols that increase fecundity and reduce generation time. The blind Mexican tetra, Astyanax mexicanus, is an emerging genetic vertebrate model for evolution and biomedical research. Surface and cave populations of A. mexicanus have independently evolved, providing a model system for studying the genetic basis of divergent biological traits. While a rapid increase in the use of A. mexicanus has led to the generation of genetic tools including gene-editing and transgenesis, a slow and inconsistent growth rate remains a major limitation to the expanded application of A. mexicanus. The optimization of husbandry protocols that maximizes high-nutrient feed, smaller tank densities and larger tank sizes across development, would facilitate faster growth and expand the use of this model. Here, we describe standardized husbandry practices that optimize growth through a high protein diet, increased feeding, growth sorting of larvae and juveniles, and tank size transitions based on standard length. These changes to husbandry had a significant effect on growth rates and decreased the age of sexual maturity in comparison to our previous protocols. To determine whether our nutritional change and increased feeding impacted behavior, we tested fish in exploration and schooling assays. We found that a change in diet had no effect on the behaviors we tested, suggesting that increased feeding and rapid growth will not impact the natural variation in behavioral traits. Taken together, this standardized husbandry protocol will accelerate the development of A. mexicanus as a genetic model.

evolutionary biology↗

bioRxiv2022

A brain-wide analysis maps structural evolution to distinct anatomical modules

Brain anatomy is highly variable and it is widely accepted that anatomical variation impacts brain function and ultimately behavior. The structural complexity of the brain, including differences in volume and shape, presents an enormous barrier to define how variability underlies differences in function. In this study, we sought to investigate the evolution of brain anatomy in relation to brain region volume and shape across the brain of a single species with variable genetic and anatomical morphs. We generated a high-resolution brain atlas for the blind Mexican cavefish and coupled the atlas with automated computational tools to directly assess brain region shape and volume variability across all populations. We measured the volume and shape of every neuroanatomical region of the brain and assess correlations between anatomical regions in surface, cavefish and surface to cave F2 hybrids, whose phenotypes span the range of surface to cave. We find that dorsal regions of the brain are contracted in cavefish, while ventral regions have expanded. Interestingly, in hybrid fish the volume and shape of dorsal regions are inversely proportional to ventral regions. This trend is true for both volume and shape, suggesting that these two parameters share developmental mechanisms necessary for remodeling the entire brain. Given the high conservation of brain anatomy and function among vertebrate species, we expect these data to studies reveal generalized principles of brain evolution and show that Astyanax provides a system for functionally determining basic principles of brain evolution by utilizing the independent genetic diversity of different morphs, to test how genes influence early patterning events to drive brain-wide anatomical evolution.

neuroscience↗