3 research outputs found
An evaluation of the effects of over-production of ABA on whole plant water use, growth and productivity
Get PDFPredicted climate change and increasing global populations suggest that water
will become an increasingly scarce and valuable commodity. Breeding plants which
produce equivalent yields with reduced water input is therefore vital to sustain and
increase crop production in the future. The phytohormone, abscisic acid (ABA), is
important in controlling plant responses to water stress. It may be possible to
improve water use efficiency (WUE) by genetically modifying tomato and other
species to maintain elevated levels of ABA under optimal (unstressed) conditions,
thereby manipulating an intrinsic signalling mechanism which is known to mediate
drought-induced alterations of stomatal behaviour.
ABA is synthesised via the oxidative cleavage of C40 epoxycarotenoid precursors, a
reaction catalysed by the key enzyme 9-cis-epoxycarotenoid dioxygenase (NCED).
Pure breeding transgenic tomato lines constitutively over-expressing LeNCED1,
known as sp5 and sp12, both have elevated ABA concentrations, which reduce
stomatal conductance under optimal (unstressed) growth conditions, thus conserving
soil water during periods when corresponding wild type (WT) control plants were
inefficient in its use. Under well-watered conditions, whole plant transpiration
efficiency (TEp) was significantly greater in both 'high ABA' lines (sp12 and sp5)
than in WT plants.
The over-expression of LeNCED1 was combined with over-expression of a gene
(LeBCH2) encoding β-carotene hydroxylase (BCH), an enzyme acting earlier in the
ABA biosynthetic pathway. These 'double transgene' lines (G28 and G29)
consistently exhibited further improvements in ABA accumulation and TEp relative
to corresponding 'single transgene' parental lines. Lines G28 and G29 respectively
exhibited 37 and 54 % improvements in TEp relative to WT controls.
When evaluated as a potential 'high ABA' rootstock, it was found that the 'double
transgene' G29 line did not provide a sufficiently strong root-sourced signal to affect
the stomatal behaviour of scions. To increase ABA biosynthesis in the roots further,
a programme designed to combine the over-expression of three ABA biosynthetic
genes (LeNCED1; LeBCH2; LePSY1) was initiated with the objective of obtaining a
rootstock which produced sufficient ABA to affect stomatal behaviour when grafted
onto WT scions. Unfortunately, there was insufficient time to complete this work by
the end of the period reported in this thesis, although the programme is ongoing
Facial motion perception in autism spectrum disorder and neurotypical controls
Get PDFThis thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University LondonFacial motion provides an abundance of information necessary for mediating social communication. Emotional expressions, head rotations and eye-gaze patterns allow us to extract categorical and qualitative information from others (Blake & Shiffrar, 2007). Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterised by a severe impairment in social cognition. One of the causes may be related to a fundamental deficit in perceiving human movement (Herrington et al., (2007). This hypothesis was investigated more closely within the current thesis. In neurotypical controls, the visual processing of facial motion was analysed via EEG alpha waves. Participants were tested on their ability to discriminate between successive animations (exhibiting rigid and nonrigid motion). The appearance of the stimuli remained constant over trials, meaning decisions were based solely on differential movement patterns. The parieto-occipital region was specifically selective to upright facial motion while the occipital cortex responded similarly to natural and manipulated faces. Over both regions, a distinct pattern of activity in response to upright faces was characterised by a transient decrease and subsequent increase in neural processing (Girges et al., 2014). These results were further supported by an fMRI study which showed sensitivity of the superior temporal sulcus (STS) to perceived facial movements relative to inanimate and animate stimuli. The ability to process information from dynamic faces was assessed in ASD. Participants were asked to recognise different sequences, unfamiliar identities and genders from facial motion captures. Stimuli were presented upright and inverted in order to assess configural processing. Relative to the controls, participants with ASD were significantly impaired on all three tasks and failed to show an inversion effect (O'Brien et al., 2014). Functional neuroimaging revealed atypical activities in the visual cortex, STS and fronto-parietal regions thought to contain mirror neurons in participants with ASD. These results point to a deficit in the visual processing of facial motion, which in turn may partly cause social communicative impairments in ASD
Proceedings of The HKIE Geotechnical Division 43rd Annual Seminar: Towards a Smart-Green-Resilient Geo-Future for World-class City
Get PDFThis seminar proceedings contain articles on the various research ideas of the academic community and practitioners presented at The HKIE Geotechnical Division 43rd Annual Seminar (GDAS2023). This seminarprovides a platform for policymakers, practitioners, and academia to share their insights and brainstorm ideas with a view to seizing future opportunities and shaping the new future of Hong Kong. GDAS2023 was organized by the Geotechnical Division, The Hong Kong Institution of Engineers on 19th May 2023.
Seminar Title: The HKIE Geotechnical Division 43rd Annual SeminarSeminar Acronym: GDAS2023Seminar Date: 19 May 2023Seminar Location: Hong KongSeminar Organizers: Geotechnical Division, The Hong Kong Institution of Engineers
Link to the GDAS2021 Proceedings: Proceedings of The HKIE Geotechnical Division 41st Annual Seminar
Link to the GDAS2022 Proceedings: Proceedings of The HKIE Geotechnical Division 42nd Annual Semina
