Biology subjects

Levitan, D.

Publications and source records attributed to Levitan, D..

4 recordsLinked to original sources

bioRxiv2026

The impacts of light and location on reproductive timing in the Orbicella species complex

Coral spawning events rely on tight synchronicity of gamete release to increase fertilization success by increasing gamete density in the water. Differences in spawning time can cause temporal reproductive isolation and minimize hybridization with closely related coral species. Sexual reproductive success is important as it generates the genetic diversity necessary for corals to survive large scale environmental stressors such as heat waves and bleaching events. The coordination of coral spawning events within a population maintains species boundaries and increases ecosystem-wide genetic diversity. Here we generate a database of spawning events in conjunction with depth and geographic location of the three species in the Orbicella species complex to assess variability in reproductive timing. The dataset, gathered from published papers, restoration practitioners, scientist throughout the Caribbean, contains almost three decades of data and includes 265 reproductive events. Our findings indicate that some aspects of each spawning season (month and day after the full moon) are influenced by latitude whereas others, such as spawning time in relation to local sunset, may exhibit variation based on geographic location. Combined, our results suggest that the reproductive timeframe of Orbicella spp. is triggered by factors associated with latitudinal gradients, such as the amount of energy from the sun, but the specific time of gamete release may be connected to other environmental factors that occur at a local scale or vary year-to-year.

ecology↗

bioRxiv2019

Deletion of Stk11 and Fos in BLA projection neurons alters their intrinsic excitability and impairs formation of long-term aversive memory

Conditioned taste aversion (CTA) is a form of one-trial learning dependent on basolateral amygdala projection neurons (BLApn). Its underlying cellular and molecular mechanisms are poorly understood, however. We used RNAseq from BLApn to identify learning-related changes in Stk11, a kinase with well-studied roles in growth, metabolism and development, but not previously implicated in learning. Deletion of Stk11 restricted to BLApn completely blocks memory when occurring prior to training, but not following it, despite altering neither BLApn-dependent encoding of taste palatability in gustatory cortex, nor transcriptional activation of BLApn during training. Deletion of Stk11 in BLApn also increases their intrinsic excitability. Conversely, BLApn activated by CTA to express the immediate early gene Fos had reduced excitability. BLApn knockout of Fos also increased excitability and impaired learning. These data suggest that Stk11 and Fos expression play key roles in CTA long-term memory formation, perhaps by modulating the intrinsic excitability of BLApn.

neuroscience↗

bioRxiv2019

Single and population coding of taste in the gustatory cortex of awake mice

Electrophysiological analysis has reveals much about the broad coding and neural ensemble dynamics that characterize gustatory cortical (GC) taste processing in awake rats, and about how these dynamics relate to behavior. With regard to mice, meanwhile, data concerning cortical taste coding have largely been restricted to imaging--a technique that reveals average levels of neural responsiveness, but that (currently) lacks the temporal sensitivity necessary for evaluation of fast response dynamics; furthermore, the few extant studies have thus far failed to provide consensus on basic features of coding. We have recorded the spiking activity of ensembles of GC neurons while presenting representatives of the basic taste modalities (sweet, salty, sour and bitter) to awake mice. Our first central result is the identification of similarities between rat and mouse taste processing: most mouse GC neurons (~66%) responded distinctly to multiple (3-4) tastes; temporal coding analyses further reveal, for the first time, that single mouse GC neurons sequentially code taste identity and palatability--the latter responses emerging ~0.5s after the former--with whole GC ensembles transitioning suddenly and coherently from coding taste identity to coding taste palatability. The second finding is that spatial location plays very little role in any aspect of taste responses--neither between- (anterior-posterior) nor within-mouse (dorsal-ventral) mapping revealed anatomical regions with narrow or temporally simple taste responses. These data confirm recent results showing that mouse cortical taste responses are not \"gustatopic,\" but also go beyond these imaging results to show that mice process tastes through time.

neuroscience↗

bioRxiv2018

The role of the gustatory cortex in incidental experience-evoked enhancement of later taste learning

The strength of learned associations between pairs of stimuli is affected by multiple factors, the most extensively studied of which is prior experience with the stimuli themselves. In contrast, little data is available regarding how experience with incidental stimuli (independent of any conditioning situation) impacts later learning. This lack of research is striking given the importance of incidental experience to survival. We have recently begun to fill this void using conditioned taste aversion (CTA), wherein an animal learns to avoid a taste that has been associated with malaise. We previously demonstrated that incidental exposure to salty and sour tastes (taste pre-exposure, TPE) enhances aversions learned later to sucrose. Here, we investigate the neurobiology underlying this phenomenon. First, we use immediate early gene (cFos) expression to identify gustatory cortex (GC) as a site at which TPE specifically increases the neural activation caused by taste-malaise pairing (i.e., TPE did not change cFos induced by either stimulus in isolation). Next, we use site-specific infection with the optical silencer Archaerhodopsin-T to show that GC inactivation during TPE inhibits the expected enhancements of both learning and CTA related cFos expression, a full day later. Thus, we conclude that GC is almost certainly a vital part of the circuit that integrates incidental experience into later associative learning.

neuroscience↗