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Cullen, D.

Publications and source records attributed to Cullen, D..

3 recordsLinked to original sources

Who Grows There? A Course-based Undergraduate Research Experience to explore the human microbiome through 16S DNA metabarcoding

We describe a two week Course-based Undergraduate Research Experience (CURE) to introduce students to next-generation DNA sequencing, molecular biology methods and a bioinformatic workflow. The CURE is designed to take students with little to no technical and bioinformatic experience through key steps of the protocol through scaffolded laboratory and computational practicals. Our students extract and amplify human microbiome DNA using 16S ribosomal RNA specific primers, then construct a sequencing library for Oxford Nanopore based sequencing. They taxonomically assign the sequencing reads, and determine the ecological community composition using relevant software packages. Our students were able to successfully prepare sequencing libraries and analyse the data to produce relevant figures, demonstrating they met the learning objectives of the CURE. Students identified that they had developed higher level learning as defined by Blooms taxonomy, and that their confidence in practical work significantly increased as a result of doing the CURE. We share recommendations for implementation of the CURE in undergraduate curricula, and adaptations of the methods for use in schools outreach. Our CURE successfully provides training for students in genetic analysis in an enjoyable and relatively time and cost efficient manner, preparing them for future research or careers in modern molecular biology techniques.

scientific communication and education↗

The ultrasound guide: katydid ear pinnae code for bat call detection

Early predator detection is a key component of the predator-prey arms race, and has driven the evolution of multiple animal hearing systems. Katydids (Insecta) have sophisticated ears, each consisting of paired tympana on each foreleg that receive sound directly externally, and internally via a narrowing ear canal through the acoustic spiracle. These ears are pressure-time difference receivers capable of sensitive and accurate directional hearing across a wide frequency range, despite the small size of katydids. Many katydid species have cuticular pinnae which form cavities around the outer tympanal surfaces, but their function is unknown. We investigated pinnal function in the katydid Copiphora gorgonensis by combining experimental biophysics and numerical modelling using 3D ear geometries. Results show that the pinnae in C. gorgonensis do not assist in directional hearing for specific call frequencies, but instead pinnae act as ultrasound detector devices. Pinnae induced large sound pressure gains that enhanced sound detection at high ultrasonic frequencies (> 60 kHz), matching the echolocation range of co-occurring insectivorous bats. Comparing pinnal mechanics of sympatric katydid species supports these findings, and suggests that pinnae evolved in katydids primarily for enhanced predator detection. Audiograms (both behavioural and neural) and tympanal cavity resonances obtained from living specimens corroborate our findings.

biophysics↗

The foliar endophyte Phialocephala scopiformis DAOMC 229536 secretes enzymes supporting growth on wood as sole carbon source

The conifer needle endophyte, Phialocephala scopiformis, was cultivated in media containing ground Pinus contorta wood as sole carbon source. After five and seven days growth, concentrated extracellular fluids were subjected to LC-MS/MS analyses. A total of 590 proteins were identified of which 99 were assigned to glycoside hydrolase families within the Carbohydrate Active Enzyme (CAzyme) system. Multiple isozymes of exo-and endo-acting cellulases were among the most abundant proteins, and oxidative degradation of cellulose was supported by the presence of lytic polysaccharide monooxygenases, glucooligosaccharide oxidase and cellobiose dehydrogenase. Oxidoreductases were also plentiful and included GMC oxidoreductases, alcohol dehydrogenases, laccases, copper radical oxidases, tyrosinases and catalase. The expression and diversity of extracellular oxidoreductases indicates a capacity to metabolize alcohols and aromatic compounds.

microbiology↗