Biology subjects

Wilson, A.

Publications and source records attributed to Wilson, A..

5 recordsLinked to original sources

bioRxiv2018

Differential effects of conspecific and heterospecific density on the development of Aedes aegypti and Aedes albopictus larvae

O_LIBetween-species competition shapes the distribution and abundance of populations. Aedes aegypti and Ae. albopictus are vectors of pathogens such as dengue and are known to compete at the larval stage.\nC_LIO_LIThe outcome of this inter-species competition has been found to be context dependent, with the strength and direction changing with resource availability and type. We were motivated by this uncertainty, and aimed to elucidate the magnitude and mechanism of competition.\nC_LIO_LIWe manipulated the larval density of mixed and single species cohorts of larvae, measuring the effects on survivorship and development time. Unlike other related studies, we adjusted the feeding regime so that the per-capita resource availability was kept constant across all density treatments, at a level sufficient for successful development. This ensured that each larvae at least had the opportunity to gain the requisite resources for pupation.\nC_LIO_LIOur analysis found that Ae. aegypti suffered notably less mortality due to intra- and interspecific competition. For both species, intra- and interspecific competition led to the survival of faster developing individuals, with the exception that slower developing Ae. albopictus larvae survived when exposed a combination of both high con- and heterospecific densities.\nC_LIO_LIThese results show that the competition between Ae. aegypti and Ae. albopictus can still occur even when resources are theoretically adequate for development. This suggests that larvae can alter resource seeking and consumption parameters when exposed to high densities of conspecifics and heterospecifics, leading to contest competition. Evidence for resource-independent mechanisms of competition such as crowding are also found, as is evidence for the importance of demographic stochasticity in population processes.\nC_LI

ecology↗

bioRxiv2018

Native RNA sequencing on nanopore arrays redefines the transcriptional complexity of a viral pathogen

Viral genomes exhibit a higher gene density and more diversified transcriptome than the host cell. Coding potential is maximized through the use of multiple reading frames, placement of genes on opposing strands, inefficient or modified use of termination signals, and the deployment of complex alternative splicing patterns. As a consequence, detailed characterization of viral transcriptomes by conventional methods can be challenging. Full length native RNA sequencing (nRNA-seq) using nanopore arrays offers an exciting alternative. Individual transcripts are sequenced directly, without the biases inherent to the recoding or amplification steps included in other sequencing methodologies. nRNA-seq simplifies the detection of variation brought about by RNA splicing, use of alternative transcription initiation and termination sites, and other RNA modifications. Here we use nRNA-seq to profile the herpes simplex virus type 1 transcriptome during early and late stages of productive infection of primary cells. We demonstrate the effectiveness of the approach and identify a novel class of intergenic transcripts, including an mRNA that accumulates late in infection that codes for a novel fusion of the viral E3 ubiquitin ligase ICP0 and viral membrane glycoprotein L.

microbiology↗

bioRxiv2017

The unconventional kinetoplastid kinetochore protein KKT4 tracks with dynamic microtubule tips

Kinetochores are multiprotein machines that drive chromosome segregation in all eukaryotes by maintaining persistent, load-bearing linkages between the chromosomes and the tips of dynamic spindle microtubules. Kinetochores in commonly studied eukaryotes are assembled from widely conserved components like the Ndc80 complex that directly binds microtubules. However, in evolutionarily-divergent kinetoplastid species such as Trypanosoma brucei, which causes sleeping sickness, the kinetochores assemble from a unique set of proteins lacking homology to any known microtubule-binding domains. Here we show that a kinetochore protein from T. brucei called KKT4 binds directly to microtubules, diffuses along the microtubule lattice, and tracks with disassembling microtubule tips. The protein localizes both to kinetochores and to spindle microtubules in vivo, and its depletion causes defects in chromosome segregation. We define a minimal microtubule-binding domain within KKT4 and identify several charged residues important for its microtubule-binding activity. Laser trapping experiments show that KKT4 can maintain load-bearing attachments to both growing and shortening microtubule tips. Thus, despite its lack of similarity to other known microtubule-binding proteins, KKT4 has key functions required for harnessing microtubule dynamics to drive chromosome segregation. We propose that it represents a primary element of the kinetochore-microtubule interface in kinetoplastids.

cell biology↗

bioRxiv2017

Assessing the quality of supplementary sensory feedback using a crossmodal congruency task

Peripheral nerve interfaces show promise in making prosthetic limbs more biomimetic and ultimately more intuitive and useful for patients. However, approaches to assess these emerging technologies are limited in their scope and the insight they provide. When outfitting a prosthesis with a new feedback system it would be helpful to quantify its physiological correspondence, i.e. how well the experimental feedback mimics the perceived feedback in an intact limb. Here we present an approach to quantify physiological correspondence using a modified crossmodal congruency task. We trained 60 able-bodied subjects to control a bypass prosthesis under different feedback conditions and training durations. We find that the crossmodal congruency effect (CCE) score is sensitive to changes in feedback modality (multi-way ANOVA; F(2,48) = 6.02, p<0.05). After extended training, the CCE score increased as the spatial separation between expected and perceived feedback decreased (unpaired t-test, p<0.05). We present a model that can quantitatively estimate physiological correspondence given the CCE result and the measured spatial separation of the feedback. This quantification approach gives researchers a tool to assess an aspect of emerging augmented feedback systems that is not measurable with current motor assessments.

neuroscience↗

bioRxiv2017

The crossmodal congruency effect, a tool incorporation metric, suffers from a learning effect with repeated exposures

The incorporation of feedback into a persons body schema is well established. The crossmodal congruency effect (CCE) task is used to objectively quantify incorporation without being susceptible to experimenter biases. This visual-tactile interference task is used to calculate the CCE score as a difference in response time for incongruent and congruent trials. Here we show that this metric is susceptible to a learning effect that causes attenuation of the CCE score due to repeated task exposure sessions. We demonstrate that this learning effect is persistent, even after a 6 month hiatus in testing. Two mitigation strategies are proposed: 1. Only use CCE scores that are taken after learning has stabilized, or 2. Use a modified CCE protocol that decreases the task exposure time. We show that the modified and shortened CCE protocol, which may be required to meet time or logistical constraints in laboratory or clinical settings, reduced the impact of the learning effect on CCE results. Importantly, the CCE scores from the modified protocol were not significantly more variable than results obtained with the original protocol. This study highlights the importance of considering exposure time to the CCE task when designing experiments and suggests two mitigation strategies to improve the utility of this psychophysical assessment.

neuroscience↗