Biology subjects

Bevitt, J. J.

Publications and source records attributed to Bevitt, J. J..

3 recordsLinked to original sources

bioRxiv2023

Neutron capture enhances dose and reduces cancer cell viability in and out of beam during helium and carbon ion therapy.

PurposeNeutron Capture Enhanced Particle Therapy (NCEPT) is a proposed augmentation of charged particle therapy which exploits thermal neutrons generated internally, within the treatment volume via nuclear fragmentation, to deliver a biochemically targeted radiation dose to cancer cells. This work is the first experimental demonstration of NCEPT, performed using both carbon and helium ion beams with two different targeted neutron capture agents (NCAs). Materials and MethodsHuman glioblastoma cells (T98G) were irradiated by carbon and helium ion beams in the presence of NCAs, [10B]-BPA and [157Gd]-DOTA-TPP. Cells were positioned within a PMMA phantom either laterally adjacent to, or within, a 100x100x60 mm spread out Bragg peak (SOBP). The impact of NCAs and location relative to the SOBP on the cells was measured by cell growth and survival assays in six independent experiments. Neutron fluence within the phantom was characterised by quantifying the neutron activation of gold foil. ResultsCells placed inside the treatment volume reached 10% survival by 2 Gy of C or 2-3 Gy of He in the presence of NCAs compared to 5 Gy of C and 7 Gy of He with no NCA. Cells placed adjacent to the treatment volume showed a dose-dependent decrease in cell growth when treated with NCAs, reaching 10% survival by 6 Gy of C or He (to the treatment volume), compared to a no detectable effect on cells without NCA. The mean thermal neutron fluence at the centre of the SOBP was approximately 2.2x109 n/cm2/Gy(RBE) for the carbon beam and 5.8x109 n/cm2/Gy(RBE) for the helium beam and gradually decreased in all directions. ConclusionsThe addition of NCAs to cancer cells during C and He beam irradiation has a measurable impact on cell survival and growth in-vitro. Through the capture of internally generated neutrons, NCEPT introduces the concept of a biochemically targeted radiation dose to charged particle therapy. NCEPT enables the established pharmaceuticals and concepts of neutron capture therapy to be applied to a wider range of deeply situated and diffuse tumours, by targeting this dose to micro-infiltrates and cells outside of defined treatment regions. These results also demonstrate the potential for NCEPT to provide an increased dose to tumour tissue within the treatment volume, with a reduction in radiation doses to off target tissue.

biophysics↗

bioRxiv2022

Earliest evidence for frugivory and seed dispersal by birds

The Early Cretaceous diversification of birds was a major event in the history of terrestrial ecosystems, occurring during the earliest phase of the Cretaceous Terrestrial Revolution. Frugivorous birds play an important role in seed dispersal today, and may have done so since their origins. However, evidence of this has been lacking. Jeholornis is one of the earliest-diverging birds, only slightly more derived than Archaeopteryx, but its cranial anatomy has been poorly understood, obscuring diet-related functional interpretations. Originally hypothesised to be granivorous based on seeds preserved as gut contents, this interpretation has become controversial. We conducted high-resolution synchrotron tomography on an exquisitely preserved new skull of Jeholornis, revealing remarkable cranial plesiomorphies combined with a specialised rostrum. We use this to provide a near-complete cranial reconstruction of Jeholornis, and exclude the possibility that Jeholornis was granivorous, based on morphometric analyses of the mandible (3D) and cranium (2D), and comparisons with the 3D alimentary contents of extant birds. We show that Jeholornis was at least seasonally frugivorous, providing the earliest evidence for fruit consumption in birds, and indicating that seed dispersal was present from early in the avian radiation. As highly-mobile seed dispersers, early frugivorous birds could expand the scope for biotic dispersal in plants, and may explain, in part, the subsequent evolutionary expansion of fruits, indicating a potential role of bird-plant interactions in the Cretaceous Terrestrial Revolution.

paleontology↗

bioRxiv2020

The tiny Cretaceous stem-bird Oculudentavis revealed as a bizarre lizard

Oculudentavis khaungraae was described based on a tiny skull trapped in amber. The slender tapering rostrum with retracted osseous nares, large eyes, and short vaulted braincase led to its identification as the smallest avian dinosaur on record, comparable to the smallest living hummingbirds. Despite its bird-like appearance, Oculudentavis showed several features inconsistent with its original phylogenetic placement. Here we describe a more complete, specimen that demonstrates Oculudentavis is actually a bizarre lizard of uncertain position. The new interpretation and phylogenetic placement highlights a rare case of convergent evolution rarely seen among reptiles. Our results re-affirm the importance of Myanmar amber in yielding unusual taxa from a forest ecosystem rarely represented in the fossil record.

paleontology↗