Biology subjects

Galbraith, J.

Publications and source records attributed to Galbraith, J..

4 recordsLinked to original sources

bioRxiv2024

AMHY and sex determination in egg-laying mammals

The sex chromosomes of egg-laying mammals (monotremes), which lack the sex determining gene SRY1, evolved independently to those of all therian mammals2,3. Here we characterise the candidate monotreme sex determining gene, the Y-localised anti-Mullerian hormone gene (AMHY)4,3 and trace its expression during the period of sexual differentiation. Monotreme AMHX and AMHY gametologues have significant sequence divergence at the promoter, gene and protein level, likely following an original allele inversion in the common monotreme ancestor but retain conserved features of TGF-{beta} molecules. Expression of sexual differentiation genes in the echidna fetal gonad were significantly different from that of therian mammals. AMHY expression was seen exclusively in the male gonad during sexual differentiation, whereas AMHX was expressed in both sexes. Experimental ectopic expression of platypus AMHX or AMHY in the chicken embryo did not masculinise the female urogenital system, a possible result of mammalian specific changes to AMH proteins preventing function in the chicken. Our results provide fundamental insight into the first steps of monotreme sex chromosome evolution and sex determination with developmental expression data strongly supporting AMHY as the primary male sex determination gene.

evolutionary biology↗

bioRxiv2021

Dominant Effect Of Host Genetics On Skin Microbiota Composition In Homeostasis And Wound Healing

Animal microbiota have complex interactions with hosts and environment that determines its composition. Yet the ability of hosts to determine their microbiota composition is less well studied. In this study, to investigate the role host genetics in determining skin microbiota, we used 30 different mouse strains from the recombinant inbred panel, the Collaborative Cross. Murine skin microbiota composition was strongly dependent on murine strain with > 50% of the variation explained by murine strain. In particular, a quantitative trait locus on chromosome 4 associates both with Staphylococcus abundance and principal-component multi-trait analyses. Additionally, excisional wound associated changes in microbiota composition were not uniform across mouse strains and were host-specific, the genetic background accounting for about 40% of the variation in microbiota. Genetic background also had the highest effect on the healing speed of wounds accounting for over 50% of the variation while mouse age and microbiota composition change accounted only for 20% and 5% of the healing speed despite reaching statistical significance. In conclusion, host genetics has a significant impact on the skin microbiota composition during both homeostasis and wound healing. These findings have long reaching implications in our understanding of associations between microbiota dysbiosis and disease.

systems biology↗

bioRxiv2019

A survey of spiking activity reveals a functional hierarchy of mouse corticothalamic visual areas

The mammalian visual system, from retina to neocortex, has been extensively studied at both anatomical and functional levels. Anatomy indicates the cortico-thalamic system is hierarchical, but characterization of cellular-level functional interactions across multiple levels of this hierarchy is lacking, partially due to the challenge of simultaneously recording activity across numerous regions. Here, we describe a large, open dataset (part of the Allen Brain Observatory) that surveys spiking from units in six cortical and two thalamic regions responding to a battery of visual stimuli. Using spike cross-correlation analysis, we find that inter-area functional connectivity mirrors the anatomical hierarchy from the Allen Mouse Brain Connectivity Atlas. Classical functional measures of hierarchy, including visual response latency, receptive field size, phase-locking to a drifting grating stimulus, and autocorrelation timescale are all correlated with the anatomical hierarchy. Moreover, recordings during a visual task support the behavioral relevance of hierarchical processing. Overall, this dataset and the hierarchy we describe provide a foundation for understanding coding and dynamics in the mouse cortico-thalamic visual system.

neuroscience↗

bioRxiv2018

A large-scale, standardized physiological survey reveals higher order coding throughout the mouse visual cortex

To understand how the brain processes sensory information to guide behavior, we must know how stimulus representations are transformed throughout the visual cortex. Here we report an open, large-scale physiological survey of neural activity in the awake mouse visual cortex: the Allen Brain Observatory Visual Coding dataset. This publicly available dataset includes cortical activity from nearly 60,000 neurons collected from 6 visual areas, 4 layers, and 12 transgenic mouse lines from 221 adult mice, in response to a systematic set of visual stimuli. Using this dataset, we reveal functional differences across these dimensions and show that visual cortical responses are sparse but correlated. Surprisingly, responses to different stimuli are largely independent, e.g. whether a neuron responds to natural scenes provides no information about whether it responds to natural movies or to gratings. We show that these phenomena cannot be explained by standard local filter-based models, but are consistent with multi-layer hierarchical computation, as found in deeper layers of standard convolutional neural networks.

neuroscience↗