scholarly journals Convergent selection on juvenile hormone signaling is associated with the evolution of eusociality in bees

2021 ◽  
Author(s):  
Beryl M Jones ◽  
Benjamin ER Rubin ◽  
Olga Dudchenko ◽  
Karen M Kapheim ◽  
Eli S Wyman ◽  
...  
Keyword(s):  
Juvenile Hormone ◽  
Chromosome Length ◽  
Hormone Signaling ◽  
Key Factors ◽  
Evolutionary Transitions ◽  
Evolution Of Eusociality ◽  
Genome Assemblies ◽  
Gains And Losses ◽  
The Brain ◽  
Different Levels

Life's most dramatic innovations, from the emergence of self-replicating molecules to highly-integrated societies, often involve increases in biological complexity. Some groups traverse different levels of complexity, providing a framework to identify key factors shaping these evolutionary transitions. Halictid bees span the transition from individual to group reproduction, with repeated gains and losses of eusociality. We generated chromosome-length genome assemblies for 17 species and searched for genes that both experienced positive selection when eusociality arose and relaxed selection when eusociality was secondarily lost. Loci exhibiting these complementary evolutionary signatures are predicted to carry costs outweighed by their importance for traits in eusocial lineages. Strikingly, these loci included two proteins that bind and transport juvenile hormone (JH) - a key regulator of insect development and reproduction. Though changes in JH abundance are frequently associated with polymorphisms, the mechanisms coupling JH to novel phenotypes are not well understood. Our results suggest novel links between JH and eusociality arose in halictids by altering transport and availability of JH in a tissue-specific manner, including in the brain. Through genomic comparisons of species encompassing both the emergence and breakdown of eusociality, we provide insights into the mechanisms targeted by selection to shape a key evolutionary transition.

Electromagnetic field in Alzheimer’s disease: a literature review of recent preclinical and clinical studies

2020 ◽  
Vol 17 ◽  
Author(s):  
Reem Habib Mohamad Ali Ahmad ◽  
Marc Fakhoury ◽  
Nada Lawand
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Disorder ◽  
In Vivo Studies ◽  
Key Factors ◽  
Potential Benefits ◽  
Preclinical And Clinical Studies ◽  
The Brain

: Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by the progressive loss of neurons leading to cognitive and memory decay. The main signs of AD include the irregular extracellular accumulation of amyloidbeta (Aβ) protein in the brain and the hyper-phosphorylation of tau protein inside neurons. Changes in Aβ expression or aggregation are considered key factors in the pathophysiology of sporadic and early-onset AD and correlate with the cognitive decline seen in patients with AD. Despite decades of research, current approaches in the treatment of AD are only symptomatic in nature and are not effective in slowing or reversing the course of the disease. Encouragingly, recent evidence revealed that exposure to electromagnetic fields (EMF) can delay the development of AD and improve memory. This review paper discusses findings from in vitro and in vivo studies that investigate the link between EMF and AD at the cellular and behavioural level, and highlights the potential benefits of EMF as an innovative approach for the treatment of AD.

scholarly journals Using electrodermal activity to validate multilevel pain stimulation in healthy volunteers evoked by thermal grills

2020 ◽  
Vol 319 (3) ◽  
pp. R366-R375
Author(s):  
Hugo F. Posada-Quintero ◽  
Youngsun Kong ◽  
Kimberly Nguyen ◽  
Cara Tran ◽  
Luke Beardslee ◽  
...  
Keyword(s):  
Tissue Injury ◽  
Electrodermal Activity ◽  
Pain Scale ◽  
Potential Harm ◽  
Electric Pulses ◽  
Stimulation Level ◽  
Highly Correlated ◽  
The Brain ◽  
Different Levels ◽  
Assessment Research

We have tested the feasibility of thermal grills, a harmless method to induce pain. The thermal grills consist of interlaced tubes that are set at cool or warm temperatures, creating a painful “illusion” (no tissue injury is caused) in the brain when the cool and warm stimuli are presented collectively. Advancement in objective pain assessment research is limited because the gold standard, the self-reporting pain scale, is highly subjective and only works for alert and cooperative patients. However, the main difficulty for pain studies is the potential harm caused to participants. We have recruited 23 subjects in whom we induced electric pulses and thermal grill (TG) stimulation. The TG effectively induced three different levels of pain, as evidenced by the visual analog scale (VAS) provided by the subjects after each stimulus. Furthermore, objective physiological measurements based on electrodermal activity showed a significant increase in levels as stimulation level increased. We found that VAS was highly correlated with the TG stimulation level. The TG stimulation safely elicited pain levels up to 9 out of 10. The TG stimulation allows for extending studies of pain to ranges of pain in which other stimuli are harmful.

scholarly journals Comparative investigations of nonlinear and linear observers for a highly manoeuvrable target in sliding mode guidance

2017 ◽  
Vol 65 (2) ◽  
pp. 233-245
Author(s):  
Y. Wang ◽  
M. Sun ◽  
S. Du ◽  
Z. Chen
Keyword(s):  
Sliding Mode ◽  
Guidance System ◽  
Key Factors ◽  
Factors Affecting ◽  
First Order ◽  
Guidance Law ◽  
Linear Observer ◽  
Overall Performance ◽  
Twisting Algorithm ◽  
Different Levels

Abstract Target manoeuvre is one of the key factors affecting guidance accuracy. To intercept highly maneuverable targets, a second-order sliding-mode guidance law, which is based on the super-twisting algorithm, is designed without depending on any information about the target motion. In the designed guidance system, the target estimator plays an essential role. Besides the existing higher-order sliding-mode observer (HOSMO), a first-order linear observer (FOLO) is also proposed to estimate the target manoeuvre, and this is the major contribution of this paper. The closed-loop guidance system can be guaranteed to be uniformly ultimately bounded (UUB) in the presence of the FOLO. The comparative simulations are carried out to investigate the overall performance resulting from these two categories of observers. The results show that the guidance law with the proposed linear observer can achieve better comprehensive criteria for the amplitude of normalised acceleration and elevator deflection requirements. The reasons for the different levels of performance of these two observer-based methods are thoroughly investigated.

scholarly journals Attention controls multisensory perception via 2 distinct mechanisms at different levels of the cortical hierarchy

PLoS Biology ◽  
2021 ◽  
Vol 19 (11) ◽  
pp. e3001465
Author(s):  
Ambra Ferrari ◽  
Uta Noppeney
Keyword(s):  
Causal Inference ◽  
Causal Structure ◽  
Multisensory Perception ◽  
Spatial Representations ◽  
Perceptual Inference ◽  
Sensory Signals ◽  
Cortical Hierarchy ◽  
Parietal Cortices ◽  
The Brain ◽  
Different Levels

To form a percept of the multisensory world, the brain needs to integrate signals from common sources weighted by their reliabilities and segregate those from independent sources. Previously, we have shown that anterior parietal cortices combine sensory signals into representations that take into account the signals’ causal structure (i.e., common versus independent sources) and their sensory reliabilities as predicted by Bayesian causal inference. The current study asks to what extent and how attentional mechanisms can actively control how sensory signals are combined for perceptual inference. In a pre- and postcueing paradigm, we presented observers with audiovisual signals at variable spatial disparities. Observers were precued to attend to auditory or visual modalities prior to stimulus presentation and postcued to report their perceived auditory or visual location. Combining psychophysics, functional magnetic resonance imaging (fMRI), and Bayesian modelling, we demonstrate that the brain moulds multisensory inference via 2 distinct mechanisms. Prestimulus attention to vision enhances the reliability and influence of visual inputs on spatial representations in visual and posterior parietal cortices. Poststimulus report determines how parietal cortices flexibly combine sensory estimates into spatial representations consistent with Bayesian causal inference. Our results show that distinct neural mechanisms control how signals are combined for perceptual inference at different levels of the cortical hierarchy.

scholarly journals Neuropeptides in modulation of Drosophila behavior: how to get a grip on their pleiotropic actions

2019 ◽  
Author(s):  
Dick R Nässel ◽  
Dennis Pauls ◽  
Wolf Huetteroth
Keyword(s):  
Expression Pattern ◽  
Internal State ◽  
Neurosecretory Cells ◽  
Higher Order ◽  
Specific Expression ◽  
Specific Expression Pattern ◽  
Pleiotropic Functions ◽  
Pleiotropic Actions ◽  
The Brain ◽  
Different Levels

Neuropeptides constitute a large and diverse class of signaling molecules that are produced by many types of neurons, neurosecretory cells, endocrines and other cells. Many neuropeptides display pleiotropic actions either as neuromodulators, co-transmitters or circulating hormones, while some play these roles concurrently. Here, we highlight pleiotropic functions of neuropeptides and different levels of neuropeptide signaling in the brain, from context-dependent orchestrating signaling by higher order neurons, to local executive modulation in specific circuits. Additionally, orchestrating neurons receive peptidergic signals from neurons conveying organismal internal state cues and relay these to executive circuits. We exemplify these levels of signaling with four neuropeptides, SIFamide, short neuropeptide F, allatostatin-A and leucokinin, each with a specific expression pattern and level of complexity in signaling.

scholarly journals Improved Understanding of the Role of Gene and Genome Duplications in Chordate Evolution With New Genome and Transcriptome Sequences

2021 ◽  
Vol 9 ◽  
Author(s):  
Madeleine E. Aase-Remedios ◽  
David E. K. Ferrier
Keyword(s):  
Chromosomal Rearrangements ◽  
Expression Patterns ◽  
Gene Families ◽  
Evolutionary Transitions ◽  
Whole Genome Duplications ◽  
Chordate Evolution ◽  
Genome Duplications ◽  
The Many ◽  
Genome Assemblies ◽  
The Impact

Comparative approaches to understanding chordate genomes have uncovered a significant role for gene duplications, including whole genome duplications (WGDs), giving rise to and expanding gene families. In developmental biology, gene families created and expanded by both tandem and WGDs are paramount. These genes, often involved in transcription and signalling, are candidates for underpinning major evolutionary transitions because they are particularly prone to retention and subfunctionalisation, neofunctionalisation, or specialisation following duplication. Under the subfunctionalisation model, duplication lays the foundation for the diversification of paralogues, especially in the context of gene regulation. Tandemly duplicated paralogues reside in the same regulatory environment, which may constrain them and result in a gene cluster with closely linked but subtly different expression patterns and functions. Ohnologues (WGD paralogues) often diversify by partitioning their expression domains between retained paralogues, amidst the many changes in the genome during rediploidisation, including chromosomal rearrangements and extensive gene losses. The patterns of these retentions and losses are still not fully understood, nor is the full extent of the impact of gene duplication on chordate evolution. The growing number of sequencing projects, genomic resources, transcriptomics, and improvements to genome assemblies for diverse chordates from non-model and under-sampled lineages like the coelacanth, as well as key lineages, such as amphioxus and lamprey, has allowed more informative comparisons within developmental gene families as well as revealing the extent of conserved synteny across whole genomes. This influx of data provides the tools necessary for phylogenetically informed comparative genomics, which will bring us closer to understanding the evolution of chordate body plan diversity and the changes underpinning the origin and diversification of vertebrates.

A Three-Component-System Hypothesis of Psychosis

1989 ◽  
Vol 155 (S5) ◽  
pp. 37-39 ◽  
Author(s):  
Hinderk M. Emrich
Keyword(s):  
Human Brain ◽  
Causative Factor ◽  
Microscopic Level ◽  
Point Of View ◽  
Component System ◽  
Pathogenetic Factor ◽  
Pet Scans ◽  
The Brain ◽  
Different Levels

Hypotheses as to the pathogenesis of schizophrenia can be discussed at different levels of a possible manifestation of the causative factor: the macroscopic-morphological, the microscopic-morphological, and the molecular. Some abnormalities have been observed on all of them: e.g. increased ventricular-brain ratios in CT, hypofrontality in SPECT and in glucographic PET-scans, and other macromorphological abnormalities (for reviews cf. Bogerts 1984; Mundt, 1986; Bogerts et al, 1987), gliosis on a microscopic level (Stevens, 1982), and an increased dopamine-binding in in vivo receptor studies (PET as well as in post-mortem studies; Cazzullo, 1988). However, the diversity and variability of these findings point to the view that rather than there being a single distinct pathogenetic factor responsible for the pathogenesis of schizophrenic psychoses, a constitutional disposition exists, which can be described as a functional dysequilibrium within the human brain. From this point of view, schizophrenia would not appear as an inherited disorder of metabolism, but as a weakness of a neurobiological ‘system’, i.e. as an interactional disorder of a complex of networks, in which the interaction between different substructures is labile in such a way that under special conditions (e.g. ‘stress’), a decompensation (functional breakdown) results. In this sense, ‘vulnerability’ to schizophrenia may be interpreted as a consequence of a constitutional deficiency of the brain which results in an inability to stabilise, under specially challenging conditions, the interaction between different substructures of the human brain. Before this ‘functional dysequilibrium-hypothesis’ (which is a special form of a constitutional structural deficiency-hypothesis) is discussed, and before the question is raised as to which are the relevant dysequilibrated components, some indication will be given as to why such an hypothesis appears plausible.

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