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ELife Dec 2023Habituation allows animals to learn to ignore persistent but inconsequential stimuli. Despite being the most basic form of learning, a consensus model on the underlying...
Habituation allows animals to learn to ignore persistent but inconsequential stimuli. Despite being the most basic form of learning, a consensus model on the underlying mechanisms has yet to emerge. To probe relevant mechanisms, we took advantage of a visual habituation paradigm in larval zebrafish, where larvae reduce their reactions to abrupt global dimming (a dark flash). We used Ca imaging during repeated dark flashes and identified 12 functional classes of neurons that differ based on their rate of adaptation, stimulus response shape, and anatomical location. While most classes of neurons depressed their responses to repeated stimuli, we identified populations that did not adapt or that potentiated their response. These neurons were distributed across brain areas, consistent with a distributed learning process. Using a small-molecule screening approach, we confirmed that habituation manifests from multiple distinct molecular mechanisms, and we have implicated molecular pathways in habituation, including melatonin, oestrogen, and GABA signalling. However, by combining anatomical analyses and pharmacological manipulations with Ca imaging, we failed to identify a simple relationship between pharmacology, altered activity patterns, and habituation behaviour. Collectively, our work indicates that habituation occurs via a complex and distributed plasticity processes that cannot be captured by a simple model. Therefore, untangling the mechanisms of habituation will likely require dedicated approaches aimed at sub-component mechanisms underlying this multidimensional learning process.
Topics: Animals; Larva; Zebrafish; Spatial Learning; Brain; Consensus; Perciformes
PubMed: 38108818
DOI: 10.7554/eLife.84926 -
Scientific Reports Dec 2023We present clinical evaluation of a mobile app for dark adaptation (DA) measurement in age-related macular degeneration (AMD) patients and in older adults...
We present clinical evaluation of a mobile app for dark adaptation (DA) measurement in age-related macular degeneration (AMD) patients and in older adults (age > 50 years) without AMD or other retinal disorders (NV). The outcome measures were the area under dark adaptation curve (AUDAC) and the time for visual sensitivity to recover by 3 log units (T). Larger AUDAC and T values indicated worse DA response. The association of AUDAC with AMD was analyzed using linear regression, while time-to-event analysis was used for T. 32 AMD patients (mean ± SD; age:72 ± 6.3 years, VA:0.09 ± 0.08 logMAR) and 25 NV subjects (mean ± sd; age:65 ± 8.7 years, VA:0.049 ± 0.07 logMAR) were measured with the app. Controlling for age, VA, and cataract severity, the AMD presence was significantly associated with higher AUDAC (β = 0.41, 95% CI 0.18-0.64, p = 0.001) and with slower sensitivity recovery (β = 0.32, 95% CI 0.15-0.69, p = 0.004). DA measurements with the app were highly correlated with those obtained with AdaptDx-an established clinical device (n = 18, ρ = 0.87, p < 0.001). AMD classification accuracy using the app was 72%, which was comparable to the 71% accuracy of AdaptDx. Our findings indicate that the mobile app provided reliable and clinically meaningful DA measurements that were strongly correlated with the current standard of care in AMD.
Topics: Humans; Aged; Middle Aged; Dark Adaptation; Mobile Applications; Visual Acuity; Cross-Sectional Studies; Macular Degeneration
PubMed: 38092820
DOI: 10.1038/s41598-023-48898-5 -
Proceedings. Biological Sciences Nov 2023Convergent evolution is widely regarded as a signature of adaptation. However, testing the adaptive consequences of convergent phenotypes is challenging, making it...
Convergent evolution is widely regarded as a signature of adaptation. However, testing the adaptive consequences of convergent phenotypes is challenging, making it difficult to exclude non-adaptive explanations for convergence. Here, we combined feather reflectance spectra and phenotypic trajectory analyses with visual and thermoregulatory modelling to test the adaptive significance of dark plumage in songbirds of the California Channel Islands. By evolving dark dorsal plumage, island birds are generally less conspicuous to visual-hunting raptors in the island environment than mainland birds. Dark dorsal plumage also reduces the energetic demands associated with maintaining homeothermy in the cool island climate. We also found an unexpected pattern of convergence, wherein the most divergent island populations evolved greater reflectance of near-infrared radiation. However, our heat flux models indicate that elevated near-infrared reflectance is not adaptive. Analysis of feather microstructure suggests that mainland-island differences are related to coloration of feather barbs and barbules rather than their structure. Our results indicate that adaptive and non-adaptive mechanisms interact to drive plumage evolution in this system. This study sheds light on the mechanisms driving the association between dark colour and wet, cold environments across the tree of life, especially in island birds.
Topics: Animals; Songbirds; Feathers; Phenotype; Body Temperature Regulation; Channel Islands; Pigmentation; Islands
PubMed: 37964520
DOI: 10.1098/rspb.2023.1914 -
Proceedings. Biological Sciences Oct 2023Members of the phylum Cnidaria include sea anemones, corals and jellyfish, and have successfully colonized both marine and freshwater habitats throughout the world. The...
Members of the phylum Cnidaria include sea anemones, corals and jellyfish, and have successfully colonized both marine and freshwater habitats throughout the world. The understanding of how cnidarians adapt to extreme environments such as the dark, high-pressure deep-sea habitat has been hindered by the lack of genomic information. Here, we report the first chromosome-level deep-sea cnidarian genome, of the anemone sp., which was 1.39 Gbp in length and contained 44 970 gene models including 14 806 tRNA genes and 30 164 protein-coding genes. Analyses of homeobox genes revealed the longest chromosome hosts a mega-array of Hox cluster, HoxL, NK cluster and NKL homeobox genes; until now, such an array has only been hypothesized to have existed in ancient ancestral genomes. In addition to this striking arrangement of homeobox genes, analyses of microRNAs revealed cnidarian-specific complements that are distinctive for nested clades of these animals, presumably reflecting the progressive evolution of the gene regulatory networks in which they are embedded. Also, compared with other sea anemones, circadian rhythm genes were lost in sp., which likely reflects adaptation to living in the dark. This high-quality genome of a deep-sea cnidarian thus reveals some of the likely molecular adaptations of this ecologically important group of metazoans to the extreme deep-sea environment. It also deepens our understanding of the evolution of genome content and organization of animals in general and cnidarians in particular, specifically from the viewpoint of key developmental control genes like the homeobox-encoding genes, where we find an array of genes that until now has only been hypothesized to have existed in the ancient ancestor that pre-dated both the cnidarians and bilaterians.
Topics: Animals; Sea Anemones; Genes, Homeobox; Phylogeny; Evolution, Molecular; Multigene Family; Cnidaria
PubMed: 37876192
DOI: 10.1098/rspb.2023.1563 -
Scientific Reports Feb 2024This study aimed to investigate how the extent and central/peripheral location of the residual visual field (VF) in patients with late-stage inherited retinal diseases... (Review)
Review
This study aimed to investigate how the extent and central/peripheral location of the residual visual field (VF) in patients with late-stage inherited retinal diseases (IRDs) are related to retinal sensitivity detected using full-field stimulus testing (FST). We reviewed the results of Goldmann perimetry and FST from the medical records of patients with IRDs whose VF represents central (within 10°) and/or peripheral islands, or undetectable. In total, 19 patients (19 eyes) were analyzed in this study. The median value of residual VF area was 1.38%. The median values of rod and cone sensitivities were - 14.9 dB and 7.4 dB, respectively. Patients with only the peripheral island (- 33.9 dB) had better median rod sensitivity than other groups (only central, - 18.9 dB; both, - 3.6 dB). VF area significantly correlated with rod sensitivity (r = - 0.943, p = 0.005) in patients with only peripheral island, but not with cone sensitivity. Peripheral VF islands were significant contributors to FST results, especially rod sensitivity. With reduced or loss of central vision, the extent of residual peripheral VF significantly affected rod sensitivity, suggesting that FST can be useful in quantitatively estimating the overall remaining vision in patients with late-stage IRD.
Topics: Humans; Visual Fields; Visual Field Tests; Dark Adaptation; Retina; Retinal Degeneration
PubMed: 38307956
DOI: 10.1038/s41598-024-53474-6 -
Plant Biotechnology Journal May 2024Higher-order chromatin structure is critical for regulation of gene expression. In plants, light profoundly affects the morphogenesis of emerging seedlings as well as...
Higher-order chromatin structure is critical for regulation of gene expression. In plants, light profoundly affects the morphogenesis of emerging seedlings as well as global gene expression to ensure optimal adaptation to environmental conditions. However, the changes and functional significance of chromatin organization in response to light during seedling development are not well documented. We constructed Hi-C contact maps for the cotyledon, apical hook and hypocotyl of soybean subjected to dark and light conditions. The resulting high-resolution Hi-C contact maps identified chromosome territories, A/B compartments, A/B sub-compartments, TADs (Topologically Associated Domains) and chromatin loops in each organ. We observed increased chromatin compaction under light and we found that domains that switched from B sub-compartments in darkness to A sub-compartments under light contained genes that were activated during photomorphogenesis. At the local scale, we identified a group of TADs constructed by gene clusters consisting of different numbers of Small Auxin-Upregulated RNAs (SAURs), which exhibited strict co-expression in the hook and hypocotyl in response to light stimulation. In the hypocotyl, RNA polymerase II (RNAPII) regulated the transcription of a SAURs cluster under light via TAD condensation. Our results suggest that the 3D genome is involved in the regulation of light-related gene expression in a tissue-specific manner.
PubMed: 38762905
DOI: 10.1111/pbi.14372 -
Documenta Ophthalmologica. Advances in... Jun 2024Leber hereditary optic neuropathy (LHON) affects retinal ganglion cells causing severe vision loss. Pattern electroretinogram and photopic negative response (PhNR) of...
PURPOSE
Leber hereditary optic neuropathy (LHON) affects retinal ganglion cells causing severe vision loss. Pattern electroretinogram and photopic negative response (PhNR) of the light-adapted (LA) full-field electroretinogram (ERG) are typically affected in LHON. In the present study, we evaluated dark-adapted (DA) and LA oscillatory potentials (OPs) of the flash ERG in genetically characterized LHON patients to dissociate slow from fast components of the response.
METHODS
Seven adult patients (mean age = 28.4 ± 5.6) in whom genetic diagnosis confirmed LHON with mtDNA or nuclear DNAJC30 (arLHON) pathogenic variants were compared to 12 healthy volunteers (mean age = 35.0 ± 12.1). Full-field ERGs were recorded from both eyes. Offline digital filters at 50, 75 and 100 Hz low cutoff frequencies were applied to isolate high-frequency components from the original ERG signals.
RESULTS
ERG a-waves and b-waves were comparable between LHON patients and controls, while PhNR was significantly reduced (p = 0.009) in LHON patients compared to controls, as expected. OPs derived from DA signals (75 Hz low cutoff frequency) showed reduced peak amplitude for OP2 (p = 0.019). LA OP differences between LHON and controls became significant (OP2: p = 0.047, OP3: p = 0.039 and OP4: p = 0.013) when the 100 Hz low-cutoff frequency filter was applied.
CONCLUSIONS
Reduced OPs in LHON patients may represent disturbed neuronal interactions in the inner retina with preserved photoreceptoral (a-wave) to bipolar cell (b-wave) activation. Reduced DA OP2 and high-cutoff LA OP alterations may be further explored as functional measures to characterize LHON status and progression.
Topics: Humans; Electroretinography; Optic Atrophy, Hereditary, Leber; Male; Adult; Female; Retinal Ganglion Cells; Photic Stimulation; Young Adult; Dark Adaptation; Middle Aged; Visual Acuity
PubMed: 38451375
DOI: 10.1007/s10633-024-09968-9 -
Microorganisms Jan 2024Gnotobiotic murine models are important to understand microbiota-host interactions. Despite the role of bacteriophages as drivers for microbiome structure and function,...
Gnotobiotic murine models are important to understand microbiota-host interactions. Despite the role of bacteriophages as drivers for microbiome structure and function, there is no information about the structure and function of the gut virome in gnotobiotic models and the link between bacterial and bacteriophage/prophage diversity. We studied the virome of gnotobiotic murine Oligo-MM12 (12 bacterial species) and reduced Altered Schaedler Flora (ASF, three bacterial species). As reference, the virome of Specific Pathogen-Free (SPF) mice was investigated. A metagenomic approach was used to assess prophages and bacteriophages in the guts of 6-week-old female mice. We identified a positive correlation between bacteria diversity, and bacteriophages and prophages. (82.4%) were the most prominent class of phages in all samples with differing relative abundance. However, the host specificity of bacteriophages belonging to class differed depending on model bacterial diversity. We further studied the role of bacteriophages in horizontal gene transfer and microbial adaptation to the host's environment. Analysis of mobile genetic elements showed the contribution of bacteriophages to the adaptation of bacterial amino acid metabolism. Overall, our results implicate virome "dark matter" and interactions with the host system as factors for microbial community structure and function which determine host health. Taking the importance of the virome in the microbiome diversity and horizontal gene transfer, reductions in the virome might be an important factor driving losses of microbial biodiversity and the subsequent dysbiosis of the gut microbiome.
PubMed: 38399658
DOI: 10.3390/microorganisms12020255 -
Physiological and Structural Changes in Leaves of Seedlings Exposed to Increasing Light Intensities.Plants (Basel, Switzerland) Apr 2024Understanding the light adaptation of plants is critical for conservation. , an endangered deciduous shrub endemic to East Asia, possesses high ornamental and...
Understanding the light adaptation of plants is critical for conservation. , an endangered deciduous shrub endemic to East Asia, possesses high ornamental and phylogeographic value. However, the weak environmental adaptability of species has limited its general growth and conservation. To obtain a deeper understanding of the growth conditions, we examined the leaf morphology and physiology via anatomical and chloroplast ultrastructural analyses following exposure to different natural light intensities (full light, 40%, and 10%). The findings indicated that seedings in the 10% light intensity had significantly improved leaf morphological characteristics and specific leaf area compared to those exposed to other intensities. The net photosynthetic rate, chlorophyll (Chl) content, photosynthetic nitrogen use efficiency (PNUE), and photosynthetic phosphorus use efficiency (PPUE) exhibited marked increases at a 10% light intensity compared to both 40% light and full light intensities, whereas the light compensation point and dark respiration levels reached their lowest values under the 10% light condition. With reduced light, leaf thickness, palisade tissue, spongy tissue, and stomatal density significantly decreased, whereas the stomatal length, stomatal width, and stomatal aperture were significantly elevated. When exposed to 10% light intensity, the ultrastructure of chloroplasts was well developed, chloroplasts and starch grain size, the number of grana, and thylakoids all increased significantly, while the number of plastoglobules was significantly reduced. Relative distance phenotypic plasticity index analysis exhibited that adapts to varying light environments predominantly by adjusting PPUE, Chl b, PNUE, chloroplast area, and the activity of PSII reaction centers. We proposed that efficiently utilizes low light to reconfigure its energy metabolism by regulating its leaf structure, photosynthetic capacity, nutrient use efficiency, and chloroplast development.
PubMed: 38732478
DOI: 10.3390/plants13091263 -
European Journal of Investigation in... Jun 2024(1) Background: The dark triad refers to a personality configuration mainly characterized by the presence of Machiavellianism, narcissism, and psychopathy. Even though...
(1) Background: The dark triad refers to a personality configuration mainly characterized by the presence of Machiavellianism, narcissism, and psychopathy. Even though adolescence is a critical stage in the development of dark triad traits, to date, this construct has not been studied among adolescents, mainly due to the lack of a measurement instrument adapted to this population. (2) Methods: Using a sample of 1642 adolescents, an adaptation of the Short Dark Triad (SD3) is proposed for this population. To this end, we performed a confirmatory factor analysis of the scale and examined its reliability and the intensity of the dark triad components by sex and sexual orientation. (3) Results: The adapted version of the scale (The Short Dark Triad-Adolescent Version; SD3-A) yielded good psychometric results. Confirmatory factor analysis corroborated the theoretical model of the three factors of dark personality. The results confirmed the greater presence of dark traits in male adolescents, and differences were observed based on sexual orientation. (4) Conclusions: The Short Dark Triad-Adolescent Version (SD3-A) is an effective and comprehensive instrument for the estimation of dark traits in adolescents and can be used as a screening test for this population.
PubMed: 38921071
DOI: 10.3390/ejihpe14060105