Biology subjects

Blanchard, M.

Publications and source records attributed to Blanchard, M..

4 recordsLinked to original sources

bioRxiv2024

Plant hormone manipulation impacts salt spray tolerance, which preempts herbivory as a driver of local adaptation in the yellow monkeyflower, Mimulus guttatus

A major challenge in evolutionary biology is identifying the selective agents and phenotypes underlying local adaptation. Local adaptation along environmental gradients may be driven by trade-offs in allocation to reproduction, growth, and herbivore resistance. To identify environmental agents of selection and their phenotypic targets, we performed a manipulative field reciprocal transplant experiment with coastal perennial and inland annual ecotypes of the common yellow monkeyflower (Mimulus guttatus). We manipulated herbivory with exclosures built in the field and exogenously manipulated gibberellin and jasmonic acid to shift allocation of plant resources among growth, reproduction, and herbivore resistance. Our hormone treatments influenced the timing of allocation to reproduction and allocation to phytochemical defense, but this shift was small relative to ecotype differences in allocation. Herbivore exclosures reduced herbivory and increased fitness of plants at the coastal site. However, this reduction in herbivory did not decrease the homesite advantage of coastal perennials. Unexpectedly, we found that the application of exogenous gibberellin increased mortality due to salt spray at the coastal site for both ecotypes. Our results suggest that divergence in salt spray tolerance, potentially mediated by ecotype differences in gibberellin synthesis or bioactivity, is a strong driver of local adaptation and preempts any impacts of herbivory in coastal habitats that experience salt spray.

evolutionary biology↗

bioRxiv2022

Altered integration of excitatory inputs onto the basal dendrites of layer 5 pyramidal neurons in a mouse model of Fragile X Syndrome

To uncover how synaptic integration of feedforward sensory inputs is affected in autism spectrum disorders (ASD), we used two-photon uncaging of caged glutamate to activate two clustered spines in the basal dendrites of layer 5 (L5) pyramidal neurons from a mouse model of Fragile X syndrome (FXS), the most common genetic cause of ASD. While subthreshold excitatory inputs integrate linearly in wild-type animals, surprisingly those with FXS summate sublinearly, contradicting what would be expected of a hyperexcitable cortex typically associated with ASD. Knockdown of the regulatory {beta}4 subunit of BK channels, rescues the synaptic integration, a result that was corroborated with numerical simulations. Taken together, these findings suggest that there is a differential impairment in the integration of feedforward sensory and feedback predictive inputs in L5 pyramidal neurons in FXS and potentially other forms of ASD. These results challenge the traditional view that FXS and other ASD are characterized by sensory hypersensitivity, but instead by hyposensitivity of sensory inputs and hypersensitivity of predictive inputs onto cortical neurons.

neuroscience↗

bioRxiv2020

The atypical Rho GTPase Rnd2 is critical for dentate granule neuron development and anxiety-like behavior during adult but not neonatal neurogenesis

Despite the central role of Rho GTPases in neuronal development, their functions in adult hippocampal neurogenesis remain poorly explored. Here, by using a retrovirus-based loss-of-function approach in vivo, we show that the atypical Rho GTPase Rnd2 is crucial for the survival, positioning, somatodendritic morphogenesis and functional maturation of adult-born dentate granule neurons. Interestingly, most of these functions are specific to granule neurons generated during adulthood since the deletion of Rnd2 in neonatally-born granule neurons only affects dendritogenesis. In addition, suppression of Rnd2 in adult-born dentate granule neurons increases anxiety-like behaviour whereas its deletion in pups has no such effect, a finding supporting the adult neurogenesis hypothesis of anxiety disorders. Thus, our results provide mechanistic insight into the differential regulation of hippocampal neurogenesis during development and adulthood, and establishes a causal relationship between Rnd2 expression and anxiety.

neuroscience↗

bioRxiv2020

Content and performance of the MiniMUGA genotyping array, a new tool to improve rigor and reproducibility in mouse research

The laboratory mouse is the most widely used animal model for biomedical research, due in part to its well annotated genome, wealth of genetic resources and the ability to precisely manipulate its genome. Despite the importance of genetics for mouse research, genetic quality control (QC) is not standardized, in part due to the lack of cost effective, informative and robust platforms. Genotyping arrays are standard tools for mouse research and remain an attractive alternative even in the era of high-throughput whole genome sequencing. Here we describe the content and performance of a new Mouse Universal Genotyping Array (MUGA). MiniMUGA, an array-based genetic QC platform with over 11,000 probes. In addition to robust discrimination between most classical and wild-derived laboratory strains, MiniMUGA was designed to contain features not available in other platforms: 1) chromosomal sex determination, 2) discrimination between substrains from multiple commercial vendors, 3) diagnostic SNPs for popular laboratory strains, 4) detection of constructs used in genetically engineered mice, and 5) an easy to interpret report summarizing these results. In-depth annotation of all probes should facilitate custom analyses by individual researchers. To determine the performance of MiniMUGA we genotyped 6,899 samples from a wide variety of genetic backgrounds. The performance of MiniMUGA compares favorably with three previous iterations of the MUGA family of arrays both in discrimination capabilities and robustness. We have generated publicly available consensus genotypes for 241 inbred strains including classical, wild-derived and recombinant inbred lines. Here we also report the detection of a substantial number of XO and XXY individuals across a variety of sample types, the extension of the utility of reduced complexity crosses to genetic backgrounds other than C57BL/6, and the robust detection of 17 genetic constructs. There is preliminary but striking evidence that the array can be used to identify both partial sex chromosome duplication and mosaicism, and that diagnostic SNPs can be used to determine how long inbred mice have been bred independently from the main stock for a significant action of the genotyped inbred samples. We conclude that MiniMUGA is a valuable platform for genetic QC and important new tool to the increase rigor and reproducibility of mouse research.

genetics↗