664 research outputs found
THE ECOLOGICAL CAUSES AND CONSEQUENCES OF PREY CHOICE AND ONTOGENETIC NICHE SHIFTS IN THE COMMON GOBY
Foraging behaviour of the common goby, Pomatoschistus microps was investigated in both the
United Kingdom and Sweden, with the aim of establishing causes and consequences of prey
choice and ontogenetic shifts in diet. Goby life-cycle could be clearly divided into two stages,
where prey choice changed abruptly from meio- to macrofauna at a standard length of 30 mm.
This diet-shift maximised net energy intake rates, as illustrated by a quantitatively validated
optimal foraging model. Intrinsic mechanisms were of greater importance than extrinsic
factors in driving this shift. Metabolism, the primary prey choice determinant, revealed
canalised and predictable diet shifts in the face of variable prey availability. This was in strong
contrast to the more usual determinants such as gape limitation or extrinsic factors, such as
habitat shift, prey availability and predation risk. Post diet-shift gobies consumed a range of
benthic macrofauna dependent on availability. This plasticity in prey choice suggested that
foraging efficiency was at some level below that expected for specialist foragers.
Translocation experiments provided support for the general assertion that learning and
experience are mechanisms through which generalist foragers could improve their foraging
efficiency. Ontogenetic changes in prey choice did not result in a trade-off between foraging
efficiency and other ecological parameters, leading to a prediction, upheld by geometric
morphometries, that there would be no change in morphology associated with this change in
diet. Conditions precluding diet shifts, and the resulting consequences, were explored using
mesocosm manipulations. Adult gobies prevented from feeding on macrofauna suffered
reduced condition and fitness. Pomatoschistus microps is an ideal species for investigations
into foraging behaviour and has provided valuable support for current foraging paradigms as
well as novel insights into the causes and consequences of prey choice
Abdominal stimulation for ventilation in tetraplegia
The respiratory system is highly compromised after a tetraplegic spinal cord injury due to paralysis of the major breathing muscles. As a result mechanical ventilation is often required and respiratory complications are a major cause of rehospitilisation, morbidity, and early mortality. Functional electrical stimulation (FES) applied acutely to the abdominal wall muscles in synchrony with a patient's volitional exhalation has been shown to improve breathing volumes and the ability to cough in spontaneously breathing tetraplegic patients. It has also been used acutely to improve breathing volumes in otherwise mechanically ventilated patients. The effect of using abdominal FES (AFES) chronically on AFES-assisted and unassisted respiratory function is currently unknown. To support clinical adoption of AFES practical systems are required. Systems that synchronise AFES with exhalation automatically have been developed but they have relied on invasive respiratory sensors.
In the first clinical study of this thesis twelve tetraplegic patients who could breathe spontaneously completed a three week AFES training programme in addition to a one week pre-training control period and a three week post-training follow up period. The results showed a significant increase in \ac{afes}-assisted forced vital capacity (FVC), and unassisted FVC, peak expiratory flow (PEF), and cough peak flow (CPF) throughout the training period. AFES-assisted PEF and CPF tended to increase over the same period, but the increase was not significant. The difference between unassisted and AFES-assisted measures did not change. Overall, there were limited changes in the outcome measures during the control and follow up periods, which suggests that the changes in outcome measures observed during the training period were a response to training.
In the second clinical study daily sessions of AFES-breathing were combined with the standard of care during the process of weaning a single tetraplegic patient from mechanical ventilation. The results showed that the approach was feasible: AFES acutely increased the duration of ventilator free breathing at the start of the weaning process and daily ventilator free breathing improved considerably during two four-week long periods of daily AFES-assisted breathing.
In the final study breathing data was recorded from ten healthy volunteers using a spirometer (the current standard), a nasal thermocouple, and piezoelectric belts wrapped around the chest and abdomen. An algorithm was written for each of the sensors so that they could be used to trigger stimulation during quiet breathing. The thermocouple system, followed by the chest belt system, were shown to be the most suitable replacement sensors for the spirometer.
The results of this thesis suggest three different applications of AFES in tetraplegia: a neurorehabilitation device that can be used to improve unassisted respiratory function in spontaneously breathing tetraplegics; a neuroprosthesis device that could be used to assist spontaneously breathing tetraplegics in times of respiratory distress, e.g. during recovery from respiratory infection; and as a method of weaning tetraplegic patients from mechanical ventilation. The realisation of these applications will be assisted by the non-invasive respiratory sensor algorithms developed in this thesis. Collectively these results have demonstrated the feasibility of several new areas of future research, which could ultimately be of great benefit to the health of patients with tetraplegia
Improving access to a multi-component intervention for caregivers and people with dementia
Acknowledgements We thank staff and volunteers from Voluntary Service Aberdeen, Forget Me Not Club, NHS Grampian, Alzheimer’s Scotland, Quarrier’s Carer Support, and Aberdeenshire Council who participated as trainers, and Zahid Quayyum at the Health Economics Research Unit of the University of Aberdeen who contributed to the economic analysis. Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Aberdeenshire Change Fund (Study 1), NHS Grampian Carers Information Strategy and Alzheimer Scotland (Study 2).Peer reviewedPostprin
A conserved set of maternal genes? Insights from a molluscan transcriptome
The early animal embryo is entirely reliant on maternal gene products for a ‘jump-start’ that transforms a transcriptionally inactive embryo into a fully functioning zygote. Despite extensive work on model species, it has not been possible to perform a comprehensive comparison of maternally-provisioned transcripts across the Bilateria because of the absence of a suitable dataset from the Lophotrochozoa. As part of an ongoing effort to identify the maternal gene that determines left-right asymmetry in snails, we have generated transcriptome data from 1 to 2-cell and ~32-cell pond snail (Lymnaea stagnalis) embryos. Here, we compare these data to maternal transcript datasets from other bilaterian metazoan groups, including representatives of the Ecydysozoa and Deuterostomia. We found that between 5 and 10% of all L. stagnalis maternal transcripts (~300-400 genes) are also present in the equivalent arthropod (Drosophila melanogaster), nematode (Caenorhabditis elegans), urochordate (Ciona intestinalis) and chordate (Homo sapiens, Mus musculus, Danio rerio) datasets. While the majority of these conserved maternal transcripts (“COMATs”) have housekeeping gene functions, they are a non-random subset of all housekeeping genes, with an overrepresentation of functions associated with nucleotide binding, protein degradation and activities associated with the cell cycle. We conclude that a conserved set of maternal transcripts and their associated functions may be a necessary starting point of early development in the Bilateria. For the wider community interested in discovering conservation of gene expression in early bilaterian development, the list of putative COMATs may be useful resource
Quantitative measures and 3D shell models reveal interactions between bands and their position on growing snail shells
The nature of shell growth in gastropods is useful because it preserves the ontogeny of shape, colour, and banding patterns, making them an ideal system for understanding how inherited variation develops, is established and maintained within a population. However, qualitative scoring of inherited shell characters means there is a lack of knowledge regarding the mechanisms that control fine variation. Here, we combine empirical measures of quantitative variation and 3D modeling of shells to understand how bands are placed and interact. By comparing five‐banded Cepaea individuals to shells lacking individual bands, we show that individual band absence has minor but significant impacts upon the position of remaining bands, implying that the locus controlling band presence/absence mainly acts after position is established. Then, we show that the shell grows at a similar rate, except for the region below the lowermost band. This demonstrates that wider bands of Cepaea are not an artifact of greater shell growth on the lower shell; they begin wider and grow at the same rate as other bands. Finally, we show that 3D models of shell shape and banding pattern, inferred from 2D photos using ShellShaper software, are congruent with empirical measures. This work therefore establishes a method that may be used for comparative studies of quantitative banding variation in snail shells, extraction of growth parameters, and morphometrics. In the future, studies that link the banding phenotype to the network of shell matrix proteins involved in biomineralization and patterning may ultimately aid in understanding the diversity of shell forms found in molluscs
Bundap Marram Durn Durn: Engagement with Aboriginal women experiencing comorbid chronic physical and mental health conditions
OBJECTIVE: To explore antecedents of health service engagement and experience among urban Aboriginal people with comorbid physical and mental health conditions. METHODS: Focus groups and interviews were conducted with Aboriginal people who had comorbid health conditions and were accessing Aboriginal and/or mainstream services. RESULTS: Nineteen participants, all women, were recruited. Participants' personal histories and prior experience of health services affected effective service utilisation. Participants' service experiences were characterised by long waiting times in the public health system and high healthcare staff turnover. Trusted professionals were able to act as brokers to other clinically and culturally competent practitioners. CONCLUSIONS: Many urban Aboriginal women attended health services with multiple comorbid conditions including chronic disease and mental health issues. Several barriers and enablers were identified concerning the capacity of services to engage and effectively manage Aboriginal patients' condition
Gene Splicing of an Invertebrate Beta Subunit (LCav?) in the N-Terminal and HOOK Domains and Its Regulation of LCav1 and LCav2 Calcium Channels
The accessory beta subunit (Cavβ) of calcium channels first appear in the same genome as Cav1 L-type calcium channels in single-celled coanoflagellates. The complexity of this relationship expanded in vertebrates to include four different possible Cavβ subunits (β1, β2, β3, β4) which associate with four Cav1 channel isoforms (Cav1.1 to Cav1.4) and three Cav2 channel isoforms (Cav2.1 to Cav2.3). Here we assess the fundamentally-shared features of the Cavβ subunit in an invertebrate model (pond snail Lymnaea stagnalis) that bears only three homologous genes: (LCav1, LCav2, and LCavβ). Invertebrate Cavβ subunits (in flatworms, snails, squid and honeybees) slow the inactivation kinetics of Cav2 channels, and they do so with variable N-termini and lacking the canonical palmitoylation residues of the vertebrate β2a subunit. Alternative splicing of exon 7 of the HOOK domain is a primary determinant of a slow inactivation kinetics imparted by the invertebrate LCavβ subunit. LCavβ will also slow the inactivation kinetics of LCav3 T-type channels, but this is likely not physiologically relevant in vivo. Variable N-termini have little influence on the voltage-dependent inactivation kinetics of differing invertebrate Cavβ subunits, but the expression pattern of N-terminal splice isoforms appears to be highly tissue specific. Molluscan LCavβ subunits have an N-terminal “A” isoform (coded by exons: 1a and 1b) that structurally resembles the muscle specific variant of vertebrate β1a subunit, and has a broad mRNA expression profile in brain, heart, muscle and glands. A more variable “B” N-terminus (exon 2) in the exon position of mammalian β3 and has a more brain-centric mRNA expression pattern. Lastly, we suggest that the facilitation of closed-state inactivation (e.g. observed in Cav2.2 and Cavβ3 subunit combinations) is a specialization in vertebrates, because neither snail subunit (LCav2 nor LCavβ) appears to be compatible with this observed property
Moderators of changes in smoking, drinking and quitting behaviour associated with the first COVID‐19 lockdown in England
Aim
To estimate changes in smoking, drinking and quitting behaviour from before to during the first COVID-19 lockdown in England, and whether changes differed by age, sex or social grade.
Design
Representative cross-sectional surveys of adults, collected monthly between August 2018 and July 2020.
Setting
England.
Participants
A total of 36 980 adults (≥ 18 years).
Measurements
Independent variables were survey month (pre-lockdown: August–February versus lockdown months: April–July) and year (pandemic: 2019/20 versus comparator: 2018/19). Smoking outcomes were smoking prevalence, cessation, quit attempts, quit success and use of evidence-based or remote cessation support. Drinking outcomes were high-risk drinking prevalence, alcohol reduction attempts and use of evidence-based or remote support. Moderators were age, sex and occupational social grade (ABC1 = more advantaged/C2DE = less advantaged).
Findings
Relative to changes during the same time period in 2018/19, lockdown was associated with significant increases in smoking prevalence [+24.7% in 2019/20 versus 0.0% in 2018/19, adjusted odds ratio (aOR) = 1.35, 95% confidence interval (CI) = 1.12–1.63] and quit attempts (+39.9 versus –22.2%, aOR = 2.48, 95% CI = 1.76–3.50) among 18–34-year-olds, but not older groups. Increases in cessation (+156.4 versus –12.5%, aOR = 3.08, 95% CI = 1.86–5.09) and the success rate of quit attempts (+99.2 versus +0.8%, aOR = 2.29, 95% CI = 1.31–3.98) were also observed, and did not differ significantly by age, sex or social grade. Lockdown was associated with a significant increase in high-risk drinking prevalence among all socio-demographic groups (+39.5 versus –7.8%, aOR = 1.80, 95% CI = 1.64–1.98), with particularly high increases among women (aOR = 2.17, 95% CI = 1.87–2.53) and social grades C2DE (aOR = 2.34, 95% CI = 2.00–2.74). Alcohol reduction attempts increased significantly among high-risk drinkers from social grades ABC1 (aOR = 2.31, 95% CI = 1.78–3.00) but not C2DE (aOR = 1.25, 95% CI = 0.83–1.88). There were few significant changes in use of support for smoking cessation or alcohol reduction, although samples were small.
Conclusions
In England, the first COVID-19 lockdown was associated with increased smoking prevalence among younger adults and increased high-risk drinking prevalence among all adults. Smoking cessation activity also increased: more younger smokers made quit attempts during lockdown and more smokers quit successfully. Socio-economic disparities in drinking behaviour were evident: high-risk drinking increased by more among women and those from less advantaged social grades (C2DE), but the rate of reduction attempts increased only among the more advantaged social grades (ABC1)
Discrete or indiscrete? Redefining the colour polymorphism of the land snail Cepaea nemoralis
Biologists have long tried to describe and name the different phenotypes that make up the shell polymorphism of the land snail Cepaea nemoralis. Traditionally, the view is that the ground colour of the shell is one of a few major colour classes, either yellow, pink or brown, but in practise it is frequently difficult to distinguish the colours, and define different shades of the same colour. To understand whether colour variation is in reality continuous, and to investigate how the variation may be perceived by an avian predator, we applied psychophysical models of colour vision to shell reflectance measures. We found that both achromatic and chromatic variation are indiscrete in Cepaea nemoralis, being continuously distributed over many perceptual units. Nonetheless, clustering analysis based on the density of the distribution did reveal three groups, roughly corresponding to human-perceived yellow, pink and brown shells. We also found large-scale geographic variation in the frequency of these groups across Europe, and some covariance between shell colour and banding patterns. Although further studies are necessary, the observation of continuous variation in colour is intriguing because the traditional theory is that the underlying supergene that determines colour has evolved to prevent phenotypes from “dissolving” into continuous trait distributions. The findings thus have significance for understanding the Cepaea polymorphism, and the nature of the selection that acts upon it, as well as more generally highlighting the need to measure colour objectively in other systems
- …