Insects use feedback from multiple sensory modalities to control their motor output. Hawkmoths are crepuscular insects that fly in low light conditions, hovering over flowers as they pollinate and feed from them. They use their long and flexible mouthpart, the proboscis, to explore flower surfaces and feed from a tiny nectary opening in these flowers. We asked how moths combine visual and mechanosensory feedback to find the nectary opening in flowers. To test the effect of light level on their efficiency in locating the nectary we combined 3D printing technology to generate artificial flowers, with micro-sensing technology that allowed us to detect the proboscis tip inside the nectary, and computer vision techniques to track the motion of hovering moths at two different light levels; 0.1 lux (moonlight) and 50 lux (dawn/dusk). Using a combination of low light videography and machine vision, we quantified how floral exploration changed between visits, and between the different light levels. We also measured the length of time moths took to find the flower nectary each visit. We found that moths took less time to find the nectary at lower (moonlight) levels compared to higher (dawn/dusk) levels. Hawkmoths are typically active in low light conditions, hence the higher light levels might be adversely affecting flight control. Moreover, preliminary reconstruction of their flight paths suggests that moths hovered over the flower in tighter trajectories under lower light conditions, as compared to the higher light conditions. These results suggest a decreased control over their flight motor output at higher light levels, resulting in reduced hover feeding. These behavioral differences have led us to a series of questions looking at the physiological effects of the different stimuli.

Dysregulation of the dopamine system is a central mechanism driving substance use disorders. Our laboratory has shown that chronic cocaine consumption decreases dopamine release in the nucleus accumbens of the rat, which is a brain area that is important in reinforcement learning. This study also found that restoring dopamine transmission through the administration of the dopaminergic drug, L-DOPA, decreased their cocaine consumption. Recently, we have also shown that acute administration of L-DOPA decreases ethanol (EtOH) intake. Thus, the present study sought to examine the effects of chronic L-DOPA on operant responding for EtOH in adult male rats. Rats were presented with a 2-bottle choice between an EtOH (20%) solution or water, daily for 21 days. Next, animals made nose poke responses (FR1) for 0.2 mLs of an EtOH (20%) solution over 1-h daily sessions for 35 days. On Days 26-35, rats consecutively received either vehicle or L-DOPA (30 mg/kg) for 5 days, counterbalanced across days, and L-DOPA decreased operant responding for EtOH compared to VEH. We are presently examining the effects of L-DOPA on dopamine release during operant responding for EtOH. Together, these data may suggest the efficacy of L-DOPA as a treatment for patients with alcoholism.

Exposure to traumatic events during infancy can lead to adverse health effects later in life, stemming from an imbalance between the innate and acquired arms of the immune system. Trauma experienced at an early age, such as childhood abuse or environmental stress, is categorized as early life adversity. As the immune consequences of early life adversity are unclear, our study explores how early life adversity affects immunological development and parasite susceptibility in gelada monkeys (Theropithecus gelada). Geladas are an ideal species to study early life adversity due to the similarity of their immune response to that of humans and the fact that they may face adversity early in life. Male geladas compete for reproductive access to females, which often leads to attempted infanticide. Surviving juveniles experience trauma that may have similar physiological consequences to early life adversity in humans. Thus, we determine if there are differences in the immune development of the acquired immune system between geladas exposed to takeovers as infants and those who were not. Acquired immune system development is measured by the identification of gastrointestinal (GI) parasites species that commonly infect geladas, as these parasites trigger the adaptive immune response. We identify these GI parasites using high throughput methods to sequence a region of DNA with known variation across nematode species, allowing us to identify parasites at the level of genus. We expect to see greater GI parasite species diversity in geladas with underdeveloped acquired immune systems as we continue to identify GI parasite species in geladas that were exposed to early life adversity and those who were not.

Gut Microbiome is increasingly recognized as a pivotal player in toxicological responses, thus dysbiosis or microbial imbalance may worsen chemical-induced adverse outcomes such as inflammation, metabolic syndrome, and cancer. Early life exposure to environmental contaminants may produce long term toxicities in adulthood, and little is known to what extent early life exposure to environmental contaminants modulate the gut microbiome beyond adulthood. Therefore, this study tested the effects of perinatal exposure to 3 human health relevant environmental contaminants (BDE-47, TBBPA, and BPS), on the composition and functions of the gut microbiome of perinatally exposed adult male mice. CD-1 mouse dams were orally exposed to vehicle (corn-oil, 10ml/kg), BDE-47 (0.2mg/kg), TBBPA (0.2mg/kg), and BPS (0.2mg/kg) once daily from gestational day 8 to the end of lactation (postnatal day 21). Feces from male pups were collected at 12-weeks of age (n=14-23/group). Microbial DNA was isolated, subjected to 16rDNA sequencing, and analyzed using QIIME. Microbial biomarkers for each chemical exposure were predicted using LefSe. Microbial functions and key taxa that drive functional changes were predicted using PICRUSt and FishTaco, respectively. None of the 3 chemicals markedly altered the overall richness of the gut microbiome in adult male pups. However, principle coordinate analysis showed a distinct separation among different exposure groups, and especially between BPS and vehicle exposure groups. A total of 73 taxa were persistently altered by at least 1 chemical exposure, among which 12 taxa were commonly regulated by all 3 chemicals. The most representative microbial biomarkers for each exposure condition were Clostridiales for vehicle, S24-7 for BDE-47, Rikenellaceae for TBBPA, and Lactobacillus for BPS. Together, these observations suggest early life exposure to these human health relevant environmental contaminants produce persistent gut dysbiosis in adult male offspring, leading to functional shifts that may play important roles in regulating certain diseases of the host.

Building upon our rat testicular o-culture system developed to improve evaluation of chemicals and identify their potential adverse health effects on humans, we have designed in vitro mouse system to expedite such assessments. Models of in vitro cell cultures are, however, limited in their approach typically using a monoculture of single cell types. Using a 3 dimensional organotypic approach can provide a framework for evaluating systematic interactions between cells with a goal to reduce the need for in vivo assessments. We utilized a novel organotypic, in vitro model of testicular development that mirrors the development shown by in vivo studies. We used isolated testicular tissue harvested from C57BL/6 male mice on post-natal day 9 and digested into a single cell suspension. Testicular co-cultures were maintained for up to 16 days in 24 well plates. Data collections occurred at days in vitro (DIV) 3, 7, and 16. These timepoints represent “windows of potential susceptibility” for testicular development. Plates were stained with antibodies providing markers corresponding to morphological features of specific cell type; six different primary antibodies were used as markers to visualize the change in cell populations; markers for Sertoli cells corresponded to Vimentin, Leydig cells with 3b-HSD, Germ cells to DAZL, SCP3 and c-kit, and proliferation with PCNA. We used an immunofluorescence dual staining technique with Scanning Laser Image Cytometery (iCys) to quantify the proportion of cell types and to determine changes in phenotypic distribution of the cell population. Our observations in vitro demonstrated concordance of changes in Sertoli cells, Leydig cells and Germ cells throughout testicular development with similar trends in vivo. Our observation of similarities in testicular development in our 3 D in vitro experiment and in vivo studies is important and supports the current trends in minimizing the need for in vivo studies for chemical toxicological.

Dynamic coordination of animal motion depends on the interaction between the neuromuscular system and body mechanics. Changes in muscle length resulting from neuromuscular activation drive the control of locomotion. This project seeks to predict change in muscle length over time based on electrical activity in the complex physiological environment of a living organism. During energetically costly insect flight, the antagonistic shortening of the dorsal longitudinal muscles (DLMs) and dorsal ventral muscles (DVMs) deform the thorax to indirectly power wing flapping. Using electromyography (EMG), we recorded both DLM and DVM activity in vivo during tethered flight of the insect model Manduca sexta. Simultaneously, we captured high-speed video of thorax deformation to measure the change in length of the DLM muscles, which attach directly to the exoskeleton. Unlike other insects, in M. sexta there is a one-to-one relationship between muscle electrical activation and length-wise contraction, allowing direct comparison between these two temporal data sets. Using machine learning, we created a model to predict the amplitude and time course of changes in muscle length 𝓁(𝑡) based on characteristics of the EMG recording. Predicting downstream insect flight mechanics based on EMG data is an exciting application of machine learning which enables us both to better understand the factors influencing muscle length in vivo, and to connect multi-scale muscle structural data through the common link of EMG data. For example, we will predict organism-level changes in muscle length that would have occurred in existing data sets of sub-cellular muscle kinematics based on EMG data collected simultaneously.

Drosophila alpha-tubulin acetylase (dTat) is an enzyme that covalently modifies microtubules by addition of acetyl groups to the microtubule lumen. Prior studies demonstrated dTat is essential for mechanosensation in Drosophila. Mutation of alpha-tubulin lysine 40, which is covalently modified by dTat, similarly compromises mechanosensation, but our preliminary results suggest that alpha-tubulin 40 mutation and dTat mutation differentially affect some forms of somatosensation. Consistent with this observation, recent studies suggest that dTat may additionally regulate microtubule stability independent of its enzymatic activity. Whether this non-enzymatic function of dTat influences neuronal function remains to be determined. In my studies, I aim to determine the relative contributions of enzymatic and non-enzymatic functions of dTat to somatosensory function in Drosophila larvae. To this end, I have assayed requirements for dTat function in a variety of larval mechanosensory and thermal responses, which are governed by defined classes of somatosensory neurons. For each of these behaviors, I used transgenes to resupply dTat function to dTat mutant flies, comparing the ability of wild type and enzyme-dead versions of dTat to support neuronal function. Results from these studies provide an entry point to understanding enzyme-independent function of dTat.