Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
203
result(s) for
"Taylor, Graham (Graham John)"
Sort by:
Reproductive success of Eastern Bluebirds (Sialia sialis) varies with the timing and severity of drought
Drought affects avian communities in complex ways. We used our own and citizen science-generated reproductive data acquired through The Cornell Lab of Ornithology's NestWatch Program, combined with drought and vegetation indices obtained from governmental agencies, to determine drought effects on Eastern Bluebird (Sialia sialis L.) reproduction across their North American breeding range for the years 2006-2013. Our results demonstrate that some aspects of bluebird reproductive success vary with the timing and severity of drought. Clutch size was unaffected by any level of drought at the time of clutch initiation or during the 30 to 60 days prior to clutch initiation. Hatching and fledging rates decreased as drought severity increased. Drought conditions occurring at least 30 days prior to the date eggs should have hatched and 60 days prior to the date offspring should have fledged negatively affected reproduction. We also demonstrate the value of datasets generated by citizen scientists in combination with climate data for examining biotic responses at large temporal and spatial scales.
Journal Article
Differential pheromone profile as a contributor to premating isolation between two sympatric sibling fruit fly species
Abstract
Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) are sibling fruit fly species that are sympatric over much of their ranges. Premating isolation of these close relatives is thought to be maintained in part by allochrony—mating activity in B. tryoni peaks at dusk, whereas in B. neohumeralis, it peaks earlier in the day. To ascertain whether differences in pheromone composition may also contribute to premating isolation between them, this study used solid-phase microextraction and gas chromatography-mass spectrometry to characterize the rectal gland volatiles of a recently collected and a more domesticated strain of each species. These glands are typical production sites and reservoirs of pheromones in bactrocerans. A total of 120 peaks were detected and 50 were identified. Differences were found in the composition of the rectal gland emissions between the sexes, species, and recently collected versus domesticated strains of each species. The compositional variation included several presence/absence and many quantitative differences. Species and strain differences in males included several relatively small alcohols, esters, and aliphatic amides. Species and strain differences in females also included some of the amides but additionally involved many fatty acid esters and 3 spiroacetals. While the strain differences indicate there is also heritable variation in rectal gland emissions within each species, the species differences imply that compositional differences in pheromones emitted from rectal glands could contribute to the premating isolation between B. tryoni and B. neohumeralis. The changes during domestication could also have significant implications for the efficacy of Sterile Insect Technique control programs.
Journal Article
Reproductive success of Eastern Bluebirds
Drought affects avian communities in complex ways. We used our own and citizen science-generated reproductive data acquired through The Cornell Lab of Ornithology's NestWatch Program, combined with drought and vegetation indices obtained from governmental agencies, to determine drought effects on Eastern Bluebird (Sialia sialis L.) reproduction across their North American breeding range for the years 2006-2013. Our results demonstrate that some aspects of bluebird reproductive success vary with the timing and severity of drought. Clutch size was unaffected by any level of drought at the time of clutch initiation or during the 30 to 60 days prior to clutch initiation. Hatching and fledging rates decreased as drought severity increased. Drought conditions occurring at least 30 days prior to the date eggs should have hatched and 60 days prior to the date offspring should have fledged negatively affected reproduction. We also demonstrate the value of datasets generated by citizen scientists in combination with climate data for examining biotic responses at large temporal and spatial scales.
Journal Article
Gain and loss of TASK3 channel function and its regulation by novel variation cause KCNK9 imprinting syndrome
Background
Genomics enables individualized diagnosis and treatment, but large challenges remain to functionally interpret rare variants. To date, only one causative variant has been described for
KCNK9
imprinting syndrome (KIS). The genotypic and phenotypic spectrum of KIS has yet to be described and the precise mechanism of disease fully understood.
Methods
This study discovers mechanisms underlying
KCNK9
imprinting syndrome (KIS) by describing 15 novel
KCNK9
alterations from 47 KIS-affected individuals. We use clinical genetics and computer-assisted facial phenotyping to describe the phenotypic spectrum of KIS. We then interrogate the functional effects of the variants in the encoded TASK3 channel using sequence-based analysis, 3D molecular mechanic and dynamic protein modeling, and in vitro electrophysiological and functional methodologies.
Results
We describe the broader genetic and phenotypic variability for KIS in a cohort of individuals identifying an additional mutational hotspot at p.Arg131 and demonstrating the common features of this neurodevelopmental disorder to include motor and speech delay, intellectual disability, early feeding difficulties, muscular hypotonia, behavioral abnormalities, and dysmorphic features. The computational protein modeling and in vitro electrophysiological studies discover variability of the impact of
KCNK9
variants on TASK3 channel function identifying variants causing gain and others causing loss of conductance. The most consistent functional impact of
KCNK9
genetic variants, however, was altered channel regulation.
Conclusions
This study extends our understanding of KIS mechanisms demonstrating its complex etiology including gain and loss of channel function and consistent loss of channel regulation. These data are rapidly applicable to diagnostic strategies, as KIS is not identifiable from clinical features alone and thus should be molecularly diagnosed. Furthermore, our data suggests unique therapeutic strategies may be needed to address the specific functional consequences of
KCNK9
variation on channel function and regulation.
Journal Article
A Case Study of Eukaryogenesis: The Evolution of Photoreception by Photolyase/Cryptochrome Proteins
Eukaryogenesis, the origin of the eukaryotes, is still poorly understood. Herein, we show how a detailed all-kingdom phylogenetic analysis overlaid with a map of key biochemical features can provide valuable clues. The photolyase/cryptochrome family of proteins are well known to repair DNA in response to potentially harmful effects of sunlight and to entrain circadian rhythms. Phylogenetic analysis of photolyase/cryptochrome protein sequences from a wide range of prokaryotes and eukaryotes points to a number of horizontal gene transfer events between ancestral bacteria and ancestral eukaryotes. Previous experimental research has characterised patterns of tryptophan residues in these proteins that are important for photoreception, specifically a tryptophan dyad, a canonical tryptophan triad, an alternative tryptophan triad, a tryptophan tetrad and an alternative tetrad. Our results suggest that the spread of the different triad and tetrad motifs across the kingdoms of life accompanied the putative horizontal gene transfers and is consistent with multiple bacterial contributions to eukaryogenesis.
Journal Article
Template-based modeling of insect odorant receptors outperforms AlphaFold3 for ligand binding predictions
Insects rely on odorant receptors (ORs) to detect and respond to volatile environmental cues, so the ORs are attracting increasing interest as potential targets for pest control. However, experimental analysis of their structures and functions faces significant challenges. Computational methods such as template-based modeling (TBM) and AlphaFold3 (AF3) could facilitate the structural characterisation of ORs. This study first showed that both models accurately predicted the structural fold of MhOR5, a jumping bristletail OR with known experimental 3D structures, although accuracy was higher in the extracellular region of the protein and binding mode of their cognate ligands with TBM. The two approaches were then compared for their ability to predict the empirical binding evidence available for OR-odorant complexes in two economically important fruit fly species, Bactrocera dorsalis and B. minax. Post-simulation analyses including binding affinities, complex and ligand stability and receptor-ligand interactions (RLIs) revealed that TBM performed better than AF3 in discriminating between binder and non-binder complexes. TBM's superior performance is attributed to hydrophobicity-based helix-wise multiple sequence alignment (MSA) between available insect OR templates and the ORs for which the binding data were generated. This MSA identified conserved residues and motifs which could be used as anchor points for refining the alignments.
Journal Article
Associations between diurnally varying male volatile emissions and allochrony in 2 sibling fruit fly species (Diptera: Tephritidae)
Abstract
Allochrony can be an important premating isolating mechanism in insects but its physiological basis has seldom been determined. It operates at a diurnal scale to differentiate mating times of some closely related tephritid taxa. For example, the sympatric sibling species Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) mate at dusk and during the day, respectively. Rectal gland emissions of courting males function as sex pheromones in B. tryoni and recent evidence shows differences between the 2 species in many volatiles released from crushed rectal glands. Here we use gas chromatography–mass spectrometry to show that the head space compositions of whole male emissions of each species are generally but not invariably correlated with those of their respective rectal glands and they also differ between the species. Further, while the compositions of the whole male emissions do not vary diurnally in either species, the total amounts of the emissions do, in species-specific ways, with those of B. tryoni higher at dusk and night and those of B. neohumeralis higher during the day. Thus, the species differ substantially in their diurnal patterns of total whole fly emissions in a manner consistent with their allochrony, while the compositions of the emissions also differ substantially, which could also contribute to their premating isolation but is independent of their allochrony.
Journal Article
Construct Validity in Health Behavior Research: Interpreting Latent Variable Models Involving Self-Report and Objective Measures
Latent variable models assess the common variance across multiple indicators of a specific construct and are often used when measurement error may bias parameter estimates. However, care must be taken when interpreting the meaning of the latent construct when using item indicators that come from different measurement domains (e.g., self-report and biochemical indicators of smoking). Utilizing simulated data, we demonstrate that even though a model may be considered to have a \"good fit\" based on conventional criteria, data interpretation may be misleading or erroneous if precautions are not taken when specifying residual covariances. These findings have important implications for health-related research. Whenever different kinds of data are used to define latent variables in a health domain, exactly what items are used, and what biases may be present can affect, sometimes dramatically, (a) the definition of the latent variables and (b) the effects of the latent variables on other variables of interest.
Journal Article
Modeling Prevention Program Effects on Growth in Substance Use: Analysis of Five Years of Data from the Adolescent Alcohol Prevention Trial
The efficacy of prevention programs is typically determined through analysis of covariance. To date, a growth curve modeling approach is not used extensively in program evaluation. However, for longitudinal data there are several advantages to using this approach as compared to methods comparing means at two time points in a piecemeal fashion. In this study, latent growth curve models were used to evaluate the effect of a program on the average level of drug use, rate of change (growth) of drug use, and acceleration or deceleration in the rate of change of drug use. The study relied on data from the Adolescent Alcohol Prevention Trial, a randomized longitudinal drug use prevention program. The program consists of drug use information, resistance skills training, and normative education components. Data regarding cigarette and alcohol use were collected over a 5-year period, grade 7 to grade 11. Students receiving the normative education program had significantly lower average levels of reported cigarette and alcohol use, lower rates of growth for reported cigarette and alcohol use, and less deceleration of reported levels of cigarette and alcohol use as compared with the control group. Growth curve analysis is a powerful and effective tool with which to model change and program efficacy.
Journal Article