Biology subjects

Smith, E. S.

Publications and source records attributed to Smith, E. S..

7 recordsLinked to original sources

bioRxiv2025

Canalization of flower production across thermal environments requires Florigen and CLAVATA signaling.

The ability to maintain invariant developmental phenotypes across disparate environments is termed canalization, but few examples of canalization mechanisms are described. In plants, robust flower production across environmental gradients contributes to reproductive success and agricultural yields. Flowers are produced by the shoot apical meristem (SAM) in an auxin-dependent manner following the switch from vegetative growth to the reproductive phase. While the timing of this phase change, called the floral transition, is sensitized to numerous environmental and endogenous signals, flower formation itself is remarkably invariant across environmental conditions. Previously we found that CLAVATA peptide signaling promotes auxin-dependent flower primordia formation in cool environments, but that high temperatures can restore primordia formation through unknown mechanisms. Here, we show that heat promotes floral primordia patterning and formation in SAMs not by increased auxin production, but through the production of the mobile flowering signal, florigen, in leaves. Florigen, which includes FLOWERING LOCUS T (FT) and its paralog TWIN SISTER OF FT (TSF) in Arabidopsis thaliana, is necessary and sufficient to buffer flower production against the loss of CLAVATA signaling and promotes heat-mediated primordia formation through specific SAM expressed transcriptional regulators. We find that sustained florigen production is necessary for continuous flower primordia production at warmer temperatures, contrasting florigens switch-like control of floral transition. Lastly, we show that CLAVATA signaling and florigen synergize to canalize flower production across broad temperature ranges. This work sheds light on the mechanisms governing the canalization of plant development and provides potential targets for engineering crop plants with improved thermal tolerances.

plant biology↗

bioRxiv2024

Impaired humidity sensing reduces tick survival by preventing water homeostasis

Off-host periods are critical for ticks, representing a time when environmental stress, particularly dehydration, can impact tick survival. To prevent dehydration, ticks must be able to detect and move into high humidity areas to allow for water vapor uptake. Ionotropic receptor 93a (Ir93a), which is highly expressed in the front forelegs (location of Hallers organ), increases expression following dehydration, suggesting a role for the forelegs in humidity detection. Although the Hallers organ is suggested as the site of humidity detection in ticks, humidity detection has not been extensively examined for ticks. Here, we assessed the ability of ticks to sense humidity and how altered humidity detection impacts tick survival by manipulating the Hallers organ. Permanent (cutting or heat ablation) or temporary blocking (silicone covering) of the Hallers organ impairs the ability of the American dog tick, Dermacentor variabilis, to rest in areas necessary to maintain hydration. Impaired detection of humidity did not impact tick survival when individuals were held under stable optimal conditions. Still, variable conditions (low and high humidity gradient) reduced survival through dehydration stress and decreased energy reserves, as chronic water vapor uptake is energetically expensive. Field validation of these studies in D. variabilis confirmed that humidity detection is critical to tick survival. Lastly, modeling indicates impaired humidity detection will reduce questing tick populations, specifically in the adult stages. These studies confirm that the Hallers organ is critical for humidity sensing in ticks. Without this ability, tick survival will be impaired by potential dehydration or more rapid depletion of energy reserves.

physiology↗

bioRxiv2024

Computational neurodevelopment: infant decision-making in changing environments

In recognition of the fact that most psychiatric conditions have neurodevelopmental origins, there is an increasing interest in applying the methodological and conceptual approaches from computational psychiatry to developmental cohorts. However, the challenge of acquiring and modelling behavioural responses in very young infants has thus far proven difficult to overcome. To address this we developed a novel gaze-contingent, cued-reversal paradigm that allowed 6-10 month old infants to make overt behavioural responses to assess learning of expectations and updating of behaviour in response to change. We then fit computational models to infant behaviour and, for the first time, were able to validate the winning model to the same standards as would be expected of adults (e.g. good parameter recoverability, model identifiability and simulated behavioural responses). Similar to prior findings in adults, model-based prediction error measures correlated with post-switch increases in pupil size; consistent with noradrenalines hypothesised role in learning about change. Data-driven clustering based on model parameters revealed two infant behavioural subtypes hidden within the data; one with a perseverating profile and the other with a more exploratory decision-making pattern. This approach sheds new light on the classic finding that all infants under 12 months tend to perseverate. Crucially, there were no significant differences in age between the clusters, but differences in terms of adaptive skills and temperament measured via gold-standard developmental assessments. These results prime the field for infant computational psychiatry, demonstrating that we can reliably fit models to infant data and that the parameters from such models can identify subgroups with distinct cognitive profiles that are superior to those derived from the behavioural data alone.

neuroscience↗

bioRxiv2024

Intra-species quantification reveals differences in activity and sleep levels in the yellow fever mosquito, Aedes aegypti

Aedes aegypti is an important mosquito vector of human disease with a wide distribution across the globe. Climatic conditions and ecological pressure drive differences in the biology of several populations of this mosquito, including blood-feeding behavior and vector competence. However, no study has compared activity and/or sleep among different populations/lineages of Ae. aegypti. Having recently established sleep-like states in three mosquito species with observable differences in timing and amount of sleep among species, we investigated differences in activity and sleep levels among 17 Ae. aegypti lines drawn from both its native range in Africa and its invasive range across the global tropics. Activity monitoring indicates that all the lines show consistent diurnal activity, but significant differences in activity level, sleep amount, number of sleep bouts, and bout duration were observed among the lines. Variations in specific activity and sleep parameters were explained by differences in host preference, ancestry, and human population density for the lineages collected in Africa. This study provides evidence that the diurnal sleep and activity profiles for Ae. aegypti are consistent, but there are significant population differences for Ae. aegypti sleep and activity levels and interactions with humans may significantly impact mosquito activity and sleep.

physiology↗

bioRxiv2022

A network of CLAVATA receptors buffers auxin-dependent meristem maintenance

Plant body plans are elaborated in response to both environmental and endogenous cues. How these inputs intersect to promote growth and development remains poorly understood. During reproductive development, central zone stem cell proliferation in inflorescence meristems is negatively regulated by the CLAVATA3 (CLV3) peptide signaling pathway. In contrast, floral primordia formation on meristem flanks requires the hormone auxin. Here we show that CLV3 signaling is also necessary for auxin-dependent floral primordia generation and that this function is partially masked by both inflorescence fasciation and heat-induced auxin biosynthesis. Stem cell regulation by CLAVATA signaling is separable from primordia formation but is also sensitized to temperature and auxin levels. Additionally, we uncover a novel role for the CLV3 receptor CLAVATA1 in auxin- dependent meristem maintenance in cooler environments. As such, CLV3 signaling buffers multiple auxin-dependent shoot processes across divergent thermal environments with opposing effects on cell proliferation in different meristem regions.

plant biology↗

bioRxiv2021

Behavioral and postural analyses establish sleep-like states for mosquitoes that can impact interactions with hosts

Sleep is an evolutionarily conserved process that has been described in different animal systems. For insects, sleep characterization has been primarily achieved using behavioral and electrophysiological correlates in a few systems. Sleep in mosquitoes, which are important vectors of disease-causing pathogens, has not been directly examined. This is surprising as circadian rhythms, which have been well studied in mosquitoes, influence sleep in other systems. In this study, we characterized sleep in mosquitoes using body posture analysis and behavioral correlates, and quantified the effect of sleep deprivation on sleep rebound, host landing and blood-feeding propensity. Body and appendage position metrics revealed a clear distinction between the posture of mosquitoes in their putative sleep and awake states for multiple species, which correlate with a reduction in responsiveness to host cues. Sleep assessment informed by these posture analyses indicated significantly more sleep during periods of low activity. Nighttime and daytime sleep deprivation resulting from the delivery of vibration stimuli induced sleep rebound in the subsequent phase in day and night active mosquitoes, respectively. Lastly, sleep deprivation suppressed host landing in both laboratory and field settings and also impaired blood feeding of a human host when mosquitoes would normally be active. These results suggest that quantifiable sleep states occur in mosquitoes, and highlight the potential epidemiological importance of mosquito sleep.

physiology↗

bioRxiv2020

The influence of Schizotypy on Event-Related Oscillations in Sensory Gating during early Infant Development.

Maternal schizotypic personality is thought to influence childhood risk for mental health and is a personality dimension elevated among schizophrenia-spectrum patients and their first-degree relatives, in whom neuro-oscillatory deficits have been observed. The current study investigated whether 6-month-old infants (n =46), and a subset of their biological mothers (n =34), who identified as either schizotypic (n =14) non-schizotypic (n =14), or an intermediate group (n =6), displayed reduced evoked-oscillatory activity. All mothers completed the Oxford-Liverpool Inventory of Feelings and Experiences as an index of schizotypy dimensionality. An auditory paired-tone paradigm was used to probe oscillatory activity, revealing that although the infants evoked-oscillations displayed differences between Stimulus 1 and 2, there were no group differences between infants of schizotypic and control mothers. Their mothers, however, displayed differences, with reduced amplitudes toward Stimulus 1 in schizotypic mothers; consistent with literature on early sensory processes, showing sensory gating is impaired in schizophrenia-spectrum disorders.

neuroscience↗