Biology subjects

Abrams, M. J.

Publications and source records attributed to Abrams, M. J..

4 recordsLinked to original sources

bioRxiv2024

Cholinergic regulation of sleep in the upside-down jellyfish Cassiopea

Perhaps nothing is stronger evidence of the importance of sleep than its conservation across animals [1], but the extent of its regulatory conservation is unknown. The upside-down jelly-fish Cassiopea xamachana sleeps [2], and this behavior is controlled by radially-spaced marginal ganglia. After defining a sleep-wake threshold, we compared gene expression profiles of ganglia from animals sleep-deprived for two nights and found differential expression in many sleep-related genes including GABAergic, melatonergic, and cholinergic receptors. We focused on a nicotinic acetylcholine receptor alpha subunit-like (Chrnal-E), based on its differential expression, and selected animals for a second round of RNAseq that included both light-based and mechanically-based sleep-deprivation. Combining datasets revealed a short list of differentially expressed genes, of which chrnal-E is the most recognizable and well-supported, so we investigated its potential role in sleep regulation. First, we found that chemical cholinergic neuromodulators positively regulate pacemaker activity. Then, we showed by in situ hybridization that chrnal-E is expressed primarily within the ganglia, and that the area of expression expands after sleep deprivation. Next, we developed RNAi for use in Cassiopea and determined that Chrnal-E promotes wakefulness. Finally, we sampled circadian timepoints in the field and found in control conditions, chrnal-E has lowest expression late at night, but in sleep deprived animals, chrnal-E peaks at this time, supporting a link to wakefulness. Our finding that Cassiopea sleep is regulated by the cholinergic system underscores that mechanisms of sleep conservation are deeply conserved in animal evolution.

animal behavior and cognition↗

bioRxiv2023

Sleep is required for neural network plasticity in the jellyfish Cassiopea

Sleep in animals plays roles that appear specific to the brain, including synaptic homeostasis [1], neurotransmitter regulation [2], cellular repair [3], memory consolidation [4], and neural plasticity [5,6]. Would any of these functions of sleep be relevant to an animal without a brain? The upside-down jellyfish Cassiopea xamachana, like other cnidarians, lacks a centralized nervous system, yet the animal sleeps [7]. By tracking the propensity of the radially spaced ganglia to initiate muscle contractions over several days we determined how neural activity changes between sleep and wake in a decentralized nervous system. Ganglia-network sleep/ wake activity patterns range from being highly specialized to a few ganglia, to being completely unspecialized. Ganglia specialization also changes over time, indicating a high degree of plasticity in the neural network. The ganglia that lead activity can persist or switch between sleep/wake transitions, signifying a level of local control of the behavioral state in a decentralized nervous system. Following sleep deprivation, ganglia usage becomes far more sleep specialized, demonstrating reduced network plasticity. Together, these findings identify a novel behavioral control system that is decentralized and yet displays temporal specialization and centralization, and show a role for sleep in maintaining neural network plasticity, revealing a conserved function of sleep in this brain-less animal.

neuroscience↗

bioRxiv2020

A conserved strategy for inducing appendage regeneration

Can limb regeneration be induced? Few have pursued this question, and an evolutionarily conserved strategy has yet to emerge. This study reports a strategy for inducing regenerative response in appendages, which works across three species that span the animal phylogeny. In Cnidaria, the frequency of appendage regeneration in the moon jellyfish Aurelia was increased by feeding with the amino acid L-leucine and the growth hormone insulin. In insects, the same strategy induced tibia regeneration in adult Drosophila. Finally, in mammals, L-leucine and sucrose administration induced digit regeneration in adult mice, including dramatically from mid-phalangeal amputation. The conserved effect of L-leucine and insulin/sugar suggests a key role for energetic parameters in regeneration induction. The simplicity by which nutrient supplementation can induce appendage regeneration provides a testable hypothesis across animals.

evolutionary biology↗

bioRxiv2018

3D-printable tools for developmental biology: Improving embryo injection and screening techniques through 3D-printing technology

Developmental biology requires rapid embryo injections and screening. We applied new affordable high-resolution 3D-printing to create five easily modifiable stamp-mold tools that greatly increase injection and screening speed, while simultaneously reducing the harmful aspects of these processes. We designed two stamps that use different approaches to improve the injection efficiency for two different types of embryo, first for embryos from the snail Crepidula fornicata, and second, for those from the spider Parasteatoda tepidariorum. Both drastically improved injection speeds and embryo survival rates, even in novice hands. The other three tools were designed for rapid side-by-side organism orientating and comparison. The first screening tool allows for optimal imaging in Xenopus laevis tadpoles, while the second and third facilitate rapid high-throughput screening of Xenopus tropicalis tadpoles and Danio rerio juveniles, respectively. These designs can act as templates for many injection or screening applications.

developmental biology↗