Project description:To find differentially expressed genes by comparing Fuss neurons and mutant Fuss neurons we utilised targeted DamID in Drosophila melanogaster. This not only predicts many genes expressed and nonexpressed in adult Fuss neuron populations, but also reveals Fuss being expressed in gustatory neurons, especially bitter gustatory neurons. Comparison of control and mutant datasets reveals a reduced expression of gustatory receptor gene Gr66a. Gr66a is an important component of the gustatory receptors compounds responsible for toxic compound sensation. Behaviourial tests reveal an impaired toxic compound sensation of adult Fuss mutant flies.
Project description:Bitter pit is the most important physiological disorder affecting apples. In order to ascertain the genetic bases of its incidence in apple fruit, a mapping population of ‘Braeburn’ (susceptible to bitter pit) × ‘Cameo’ (resistant to bitter pit) cultivars was used to map the trait over two growing seasons. RNA-Seq on pools of RNA extracted from fruits of three resistant and three susceptible to bitter pit progenies at post-fertilization and full maturity stages, permitted us to identify a number of candidate genes underlying genetic resistance/susceptibility to bitter pit.
Project description:The median eminence (ME) is a circumventricular organ at the base of the brain that controls body homeostasis. Tanycytes are its specialized glial cells that constitute the ventricular walls and regulate different physiological states, however individual signaling pathways in these cells are incompletely understood. Here, we identify a functional tanycyte subpopulation that expresses key taste transduction genes including bitter taste receptors, the G protein gustducin and the gustatory ion channel TRPM5 (M5). M5 tanycytes have access to blood-borne cues via processes extended towards diaphragmed endothelial fenestrations in the ME and mediate bidirectional communication between the cerebrospinal fluid and blood. This subpopulation responds to metabolic signals including leptin and other hormonal cues and is transcriptionally reprogrammed upon fasting. Acute M5 tanycyte activation induces insulin secretion and acute diphtheria toxin-mediated M5 tanycyte depletion results in impaired glucose tolerance in diet-induced obese mice. We provide a cellular and molecular framework that defines how bitter taste cells in the ME integrate chemosensation with metabolism.
Project description:The sense of taste starts with activation of receptor cells in taste buds by chemical stimuli which then communicate this signal via innervating oral sensory neurons to the CNS. The cell bodies of oral sensory neurons reside in the geniculate ganglion (GG) and nodose/petrosal/jugular ganglion. The geniculate ganglion contains two main neuronal populations, BRN3A+ somatosensory neurons that innervate the pinna, and PHOX2B+ sensory neurons that innervate the oral cavity. While much is known about the different taste bud cell subtypes, much less is known about the molecular identities of PHOX2B+ sensory subpopulations. In the GG as many as 12 different subpopulations have been predicted from electrophysiological studies, while transcriptional identities exist for only 3-6. Importantly, the cell fate pathways that diversify PHOX2B+ oral sensory neurons into these subpopulations are unknown. The transcription factor EGR4 was identified as being highly expressed in GG neurons. EGR4 deletion causes GG oral sensory neurons to lose their expression of PHOX2B and other oral sensory genes, and upregulate BRN3A. This is followed by a severe loss of chemosensory innervation of taste buds, a loss of Type II taste cells responsive to bitter, sweet, and umami stimuli, and a concomitant increase in Type I glial-like taste bud cells. These deficits culminate in a loss of nerve responses to sweet and umami taste qualities. Taken together, we identify a critical role of EGR4 in cell fate specification and maintenance of subpopulations of GG neurons, which in turn maintain the appropriate sweet and umami taste receptor cells.
Project description:T2R bitter receptors, encoded by Tas2r genes, are not only critical for bitter taste signal transduction but also important for defense against bacteria and parasites. However, little is known about whether and how Tas2r gene expression are regulated. Here, using single-cell assays for transposase-accessible chromatin with sequencing (scATAC-seq), we found that the chromatin accessibility of Tas2rs was highly cell type specific and lipopolysaccharide (LPS)-induced inflammation increased the accessibility of many Tas2rs. scATAC-seq also revealed substantial chromatin remodeling in immune response genes in taste tissue stem cells, suggesting potential long-term effects. Together, our results suggest an epigenetic mechanism connecting inflammation, Tas2r gene regulation, and altered bitter taste, which may explain heightened bitter taste that can occur with infections and cancer treatments.
Project description:An expression profiling was conducted to analyse the effect of the bitter tasting compounds denatonium benzoate (DB) or aloin on the transcriptome of human jejunal crypts compared to DMEM-treated crypts. These two bitter compounds are agonists for the human bitter taste receptor TAS2R43. We took advantage of a deletion polymorphism for TAS2R43, that exists in about 33% of the population to compare the effects of the TAS2R43 agonists in obese subjects that express (TAS2R43(+)) or do not express (TAS2R43(-)) TAS2R43. Primary jejunal crypts from lean (multi-organ donors) or obese (RYGB surgery) subjects were cultured for 24 hours and treated for 4 hours with either DMEM (control) or 1 mM DB or 30 µM aloin. In total 48 mRNA samples were subjected to RNAseq analysis.
Project description:Learning to associate cues, both directly and indirectly, with biologically significant events is essential for survival. Second-order conditioning (SOC) involves forming an association between a previously reinforced conditioned stimulus (CS1) and a new conditioned stimulus (CS2) without the presence of an unconditioned stimulus (US). The neural substrates mediating SOC, however, remain unclear. Parabrachial Calca neurons, which react to the noxious US, also respond to a CS after pairing with a US, suggesting that Calca neurons mediate SOC. We established an aversive SOC behavioral paradigm in mice and monitored Calca neuron activity via single-cell calcium imaging during conditioning and subsequent recall phases. These neurons were activated by both CS1 and CS2 after SOC. Chemogenetically inhibiting Calca neurons during CS1-CS2 pairing attenuated SOC. Thus, reactivation of the US pathway by a learned CS plays an important role in forming the association between the old and a new CS, promoting the formation of second-order memories.
Project description:Basil downy mildew (BDM) caused by Peronospora Belbahrii leads to losses in sweet basil cultivation across the world. Though resistant cultivars of basil exist, the formation of sterile offspring and the introduction of unwanted phenotypic and chemotypic traits slows breeding. Previous work by the Simon lab at Rutgers University identified pair of sweet basil cultivars; one resistant to BDM, MRI, and one susceptible, SB22. They predicted that three genes in MRI confer increased BDM resistance. RNA from infected MRI and SB22 plants was harvested during the first 3 days of infection at 4 timepoints in order to capture as many early phases of plant-pathogen interaction as possible. The goal is to develop resistance markers for use in breeding experiments.
Project description:Transcriptional profiling of sweet corn response to plant density (crowding stress). Determine the extent to which hybrid and environment influences crowding stress response and identify crowding stress transcriptional response in sweet corn