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Mosaicism-independent mechanisms contribute to Pcdh19-related epilepsy and repetitive behaviors in .Proceedings of the National Academy of... May 2024Protocadherin19 ()-related epilepsy syndrome is a rare disorder characterized by early-onset epilepsy, intellectual disability, and autistic behaviors. is located on...
Protocadherin19 ()-related epilepsy syndrome is a rare disorder characterized by early-onset epilepsy, intellectual disability, and autistic behaviors. is located on the X chromosome and encodes a calcium-dependent single-pass transmembrane protein, which regulates cell-to-cell adhesion through homophilic binding. In human, 90% of heterozygous females, containing wild-type and mutant cells due to random X inactivation, are affected, whereas mutant males, containing only mutant cells, are typically not. The current view, the cellular interference, is that the altered interactions between wild-type and mutant cells during development, rather than loss of function itself, are responsible. However, studies using knockout mice showed that the complete loss of function also causes autism-like behaviors both in males and females, suggesting that other functions of PCDH19 may also contribute to pathogenesis. To address whether mosaicism is required for -related epilepsy, we generated tadpoles with complete or mosaic loss of function by injecting antisense morpholino oligonucleotides into the blastomeres of neural lineage at different stages of development. We found that either mosaic or complete knockdown results in seizure-like behaviors, which could be rescued by antiseizure medication, and repetitive behaviors. Our results suggest that the loss of PCDH19 function itself, in addition to cellular interference, may also contribute to -related epilepsy.
Topics: Animals; Cadherins; Protocadherins; Mosaicism; Female; Epilepsy; Male; Xenopus; Behavior, Animal; Humans
PubMed: 38748583
DOI: 10.1073/pnas.2321388121 -
Protein Science : a Publication of the... Jun 2024Membrane proteins play critical physiological roles as receptors, channels, pumps, and transporters. Despite their importance, however, low expression levels often...
Membrane proteins play critical physiological roles as receptors, channels, pumps, and transporters. Despite their importance, however, low expression levels often hamper the experimental characterization of membrane proteins. We present an automated and web-accessible design algorithm called mPROSS (https://mPROSS.weizmann.ac.il), which uses phylogenetic analysis and an atomistic potential, including an empirical lipophilicity scale, to improve native-state energy. As a stringent test, we apply mPROSS to the Kv1.2-Kv2.1 paddle chimera voltage-gated potassium channel. Four designs, encoding 9-26 mutations relative to the parental channel, were functional and maintained potassium-selective permeation and voltage dependence in Xenopus oocytes with up to 14-fold increase in whole-cell current densities. Additionally, single-channel recordings reveal no significant change in the channel-opening probability nor in unitary conductance, indicating that functional expression levels increase without impacting the activity profile of individual channels. Our results suggest that the expression levels of other dynamic channels and receptors may be enhanced through one-shot design calculations.
Topics: Animals; Xenopus laevis; Algorithms; Kv1.2 Potassium Channel; Oocytes; Phylogeny; Shab Potassium Channels; Mutation; Xenopus
PubMed: 38747377
DOI: 10.1002/pro.4995 -
PeerJ 2024Invasive species threaten biodiversity globally. Amphibians are one of the most threatened vertebrate taxa and are particularly sensitive to invasive species, including...
Invasive species threaten biodiversity globally. Amphibians are one of the most threatened vertebrate taxa and are particularly sensitive to invasive species, including other amphibians. African clawed frogs () are native to Southern Africa but have subsequently become invasive on multiple continents-including multiple parts of North America-due to releases from the pet and biomedical trades. Despite their prevalence as a global invader, the impact of remains understudied. This includes the Pacific Northwest of the USA, which now hosts multiple expanding populations. For many amphibians, chemical cues communicate important information, including the presence of predators. Here, we tested the role chemical cues may play in mediating interactions between feral and native amphibians in the Pacific Northwest. We tested whether native red-legged frog () tadpoles display an antipredator response to non-native frog () or native newt (rough-skinned newts, ) predator chemical stimuli. We found that tadpoles exhibited pronounced anti-predator responses when exposed to chemical cues from but did not display anti-predator response to invasive chemical cues. We also began experimentally testing whether -which produce a powerful neurotoxin tetrodotoxin (TTX)-may elicit an anti-predator response in , that could serve to deter co-occupation. However, our short-duration experiments found that were attracted to newt chemical stimuli rather than deterred. Our findings show that likely poses a threat to native amphibians, and that these native species may also be particularly vulnerable to this invasive predator, compared to native predators, because toxic native newts may not limit invasions. Our research provides some of the first indications that native Pacific Northwest species may be threatened by feral and provides a foundation for future experiments testing potential management techniques for .
Topics: Animals; Introduced Species; Xenopus laevis; Cues; Washington; Salamandridae; Larva; Predatory Behavior; Ranidae
PubMed: 38742097
DOI: 10.7717/peerj.17307 -
The Science of the Total Environment Jul 2024Amphibians are the most threatened group of vertebrates because they have certain biological and ecological characteristics that make them sensitive to environmental...
Integration of a battery of biomarkers to evaluate the health status of field-collected frogs of Leptodactylus luctator living in ecosystems with different anthropogenic disturbances.
Amphibians are the most threatened group of vertebrates because they have certain biological and ecological characteristics that make them sensitive to environmental changes. The aim of this study was to evaluate the health status of field-collected adult frogs of Leptodactylus luctator (Amphibia, Anura) living in sites with different anthropogenic disturbances (florihorticulture, petrochemical industry and sewage discharges) and a reference site without any detectable influence of such activities. To this end, a battery of 21 biomarkers (hematological, biochemical and individual biomarkers) was studied using a multivariate approach that allows us to evaluate the relationship between them and provide information on their usefulness. The frogs at the florihorticulture, petrochemical and sewage discharges sites exhibited several biomarkers far from homeostasis. In addition, we identified 11 of 21 biomarkers that were useful indicators of the health status of the frogs and allowed discrimination between study sites in the following order: lymphocytes (98 %), neutrophils (45 %), hemoglobin (42 %), monocytes (41 %), fat body index (35 %), eosinophils (35 %), hepatosomatic index (33 %), mean corpuscular hemoglobin (32 %), thrombocytes (27 %), catalase in liver (26 %), and GST in liver (26 %). The results suggest that hematological biomarkers contribute the most to site separation, whereas biochemical biomarkers contribute the least. The integral interpretation of the results also allowed us to diagnose the different health status of L. luctator: The frogs from the petrochemical industry were the most negatively affected, followed by the frogs from the sewages discharges and finally the frogs from the florihorticulture and reference sites. This is the first field study with anurans in which so many biomarkers were examined.
Topics: Animals; Biomarkers; Environmental Monitoring; Anura; Ecosystem; Health Status
PubMed: 38740213
DOI: 10.1016/j.scitotenv.2024.173174 -
Molecular Biology and Evolution Jun 2024Nonvisual opsins are transmembrane proteins expressed in the eyes and other tissues of many animals. When paired with a light-sensitive chromophore, nonvisual opsins...
Nonvisual opsins are transmembrane proteins expressed in the eyes and other tissues of many animals. When paired with a light-sensitive chromophore, nonvisual opsins form photopigments involved in various nonvisual, light-detection functions including circadian rhythm regulation, light-seeking behaviors, and seasonal responses. Here, we investigate the molecular evolution of nonvisual opsin genes in anuran amphibians (frogs and toads). We test several evolutionary hypotheses including the predicted loss of nonvisual opsins due to nocturnal ancestry and potential functional differences in nonvisual opsins resulting from environmental light variation across diverse anuran ecologies. Using whole-eye transcriptomes of 81 species, combined with genomes, multitissue transcriptomes, and independently annotated genes from an additional 21 species, we identify which nonvisual opsins are present in anuran genomes and those that are also expressed in the eyes, compare selective constraint among genes, and test for potential adaptive evolution by comparing selection between discrete ecological classes. At the genomic level, we recovered all 18 ancestral vertebrate nonvisual opsins, indicating that anurans demonstrate the lowest documented amount of opsin gene loss among ancestrally nocturnal tetrapods. We consistently found expression of 14 nonvisual opsins in anuran eyes and detected positive selection in a subset of these genes. We also found shifts in selective constraint acting on nonvisual opsins in frogs with differing activity periods, habitats, distributions, life histories, and pupil shapes, which may reflect functional adaptation. Although many nonvisual opsins remain poorly understood, these findings provide insight into the diversity and evolution of these genes across anurans, filling an important gap in our understanding of vertebrate opsins and setting the stage for future research on their functional evolution across taxa.
Topics: Animals; Opsins; Evolution, Molecular; Anura; Phylogeny; Eye; Transcriptome; Adaptation, Physiological
PubMed: 38736374
DOI: 10.1093/molbev/msae090 -
Biochemical Pharmacology Jul 2024Although α2 was the first neuronal nicotinic acetylcholine receptor (nAChR) receptor subunit to be cloned, due to its low level of expression in rodent brain, its study...
Although α2 was the first neuronal nicotinic acetylcholine receptor (nAChR) receptor subunit to be cloned, due to its low level of expression in rodent brain, its study has largely been neglected. This study provides a comparison of the α2 and α4 structures and their functional similarities, especially in regard to the existence of low and high sensitivity forms based on subunit stoichiometry. We show that the pharmacological profiles of the low and high sensitivity forms of α2β2 and α4β2 receptors are very similar in their responses to nicotine, with high sensitivity receptors showing protracted responses. Sazetidine A, an agonist that is selective for the high sensitivity α4 receptors also selectively activates high sensitivity α2 receptors. Likewise, α2 receptors have similar responses as α4 receptors to the positive allosteric modulators (PAMs) desformylflustrabromine (dFBr) and NS9283. We show that the partial agonists for α4β2 receptors, cytisine and varenicline are also partial agonists for α2β2 receptors. Studies have shown that levels of α2 expression may be much higher in the brains of primates than those of rodents, suggesting a potential importance for human therapeutics. High-affinity nAChR have been studied in humans with PET ligands such as flubatine. We show that flubatine has similar activity with α2β2 and α4β2 receptors so that α2 receptors will also be detected in PET studies that have previously presumed to selectively detect α4β2 receptors. Therefore, α2 receptors need more consideration in the development of therapeutics to manage nicotine addiction and declining cholinergic function in age and disease.
Topics: Receptors, Nicotinic; Animals; Nicotinic Agonists; Humans; Nicotine; Xenopus laevis; Azetidines; Quinolizines; Varenicline; Azocines; Quinolizidine Alkaloids; Pyridines
PubMed: 38735444
DOI: 10.1016/j.bcp.2024.116263 -
The Science of the Total Environment Jul 2024Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the...
Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the European Union in the early 2000s. The accumulation of PCPs in the aquatic environment and their effects on non-target species make it necessary to find new, less harmful, substances. Polyethylene glycol (PEGs) and polyvinyl alcohol (PVAs) are two polymers that have increased their presence in the composition of PCPs in recent years, but little is known about the effect of their accumulation in the environment on non-target species. Through embryotoxicity tests on two common models of aquatic organisms (Danio rerio and Xenopus laevis), this work aims to increase the knowledge of PEGs and PVAs' effects on non-target species. Animals were exposed to the pollutant for 96 h. The main embryotoxicity endpoint (mortality, hatching, malformations, heartbeat rate) was recorded every 24 h. The most significant results were hatching delay in Danio rerio exposed to both chemicals, in malformations (oedema, body malformations, changes in pigmentation and deformations of spine and tail) in D. rerio and X. laevis and significant change in the heartbeat rate (decrease or increase in the rate) in both animals for all chemicals tested.
Topics: Animals; Zebrafish; Water Pollutants, Chemical; Embryo, Nonmammalian; Polyvinyl Alcohol; Polyethylene Glycols; Xenopus laevis; Toxicity Tests
PubMed: 38735322
DOI: 10.1016/j.scitotenv.2024.173154 -
Integrative Zoology May 2024Environmental DNA (eDNA) metabarcoding has emerged as a powerful, non-invasive tool for biodiversity assessments. However, the accuracy and limitations of these...
Environmental DNA (eDNA) metabarcoding has emerged as a powerful, non-invasive tool for biodiversity assessments. However, the accuracy and limitations of these assessment techniques are highly dependent on the choice of primer pairs being used. Although several primer sets have been used in eDNA metabarcoding studies of amphibians, there are few comparisons of their reliability and efficiency. Here, we employed lab- and field-tested sets of publicly available and de novo-designed primers in amplifying 83 species of amphibian from all three orders (Anura, Caudata, and Gymnophiona) and 13 families present in China to evaluate the versatility and specificity of these primers sets in amphibian eDNA metabarcoding studies. Three pairs of primers were highly effective, as they could successfully amplify all the major clades of Chinese amphibians in our study. A few non-amphibian taxa were also amplified by these primers, which implies that further optimization of amphibian-specific primers is still needed. The simultaneous use of three primer sets can completely cover all the species obtained by conventional survey methods and has even effectively distinguished quite a number of species (n = 20) in the Wenshan National Nature Reserve. No single primer set could individually detect all of the species from the studied region, indicating that multiple primers might be necessary for a comprehensive survey of Chinese amphibians. Besides, seasonal variations in amphibian species composition were also revealed by eDNA metabarcoding, which was consistent with traditional survey methods. These results indicate that eDNA metabarcoding has the potential to be a powerful tool for studying spatial and temporal community changes in amphibian species richness.
PubMed: 38730493
DOI: 10.1111/1749-4877.12832 -
Comparative Biochemistry and... Sep 2024The time course for recovery after anesthesia is poorly described for tricaine methanesulfonate (MS-222). We suggest that the baroreflex and the heart rate variability...
The time course for recovery after anesthesia is poorly described for tricaine methanesulfonate (MS-222). We suggest that the baroreflex and the heart rate variability (HRV) could be used to index the recovery of the autonomic modulation after anesthesia. We analyzed the recovery profile of behavioral and physiological parameters over time to analyze the progression of recovery after anesthesia of American bullfrogs with MS-222. Mean heart rate stabilized after 17 h, whereas the baroreflex efficiency index took 23 h and the baroreflex operating gain, 29 h. Mean arterial pressure recovered after 26 h. Power spectral density peaked at 23 h and again after 40 h. Baroreflex was a relevant component of the first phase of HRV, while autonomic modulation for resting may take longer than 40 h. We suggest that physiological recovery is a complex phenomenon with multiple progressive phases, and the baroreflex may be a useful tool to observe the first substantial recovery of post-instrumentation capacity for autonomic modulation.
Topics: Animals; Baroreflex; Heart Rate; Autonomic Nervous System; Rana catesbeiana; Aminobenzoates; Anesthesia; Male; Blood Pressure; Anesthetics
PubMed: 38729257
DOI: 10.1016/j.cbpa.2024.111654 -
Ecological and Evolutionary Physiology 2024AbstractLocomotion is essential for survival, but it requires resources such as energy and metabolites and therefore may conflict with other physiological processes that...
AbstractLocomotion is essential for survival, but it requires resources such as energy and metabolites and therefore may conflict with other physiological processes that also demand resources, particularly expensive processes such as immunological responses. This possible trade-off may impose limits on either the magnitude of immune responses or the patterns of activity and performance. Previous studies have shown that invasive species may have a depressed immune response, allowing them to maintain locomotor function and reproduction even when sick. This may contribute to the ecological success of invasive species in colonization and dispersal. In contrast, noninvasive species tend to reduce activity as a response to infection. Here, we studied the impact of a simulated infection on locomotor performance and voluntary movement in the anurans (a globally invasive species) and (a noninvasive congeneric). We found that a simulated infection reduces locomotor performance in both species, with an accentuated effect on . Voluntary movement was marginally different between species. Our data suggest that a simulated infection leads to behavioral depression and reduced locomotor performance in anurans and show that this effect is limited in the invasive . Contrasting responses to an immune challenge have been reported in the few amphibian taxa analyzed to date and suggest relationships between ecology and immunology that deserve further investigation. Specifically, a depressed immune response may underlie a propension to invasion in some species. Whether this is a general trend for invasive species remains to be tested, but our data add to the growing body of work documenting depressed immune systems in invasive species.
Topics: Animals; Introduced Species; Locomotion; Xenopus laevis; Female; Male; Species Specificity; Anura
PubMed: 38728690
DOI: 10.1086/729774