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Correction: A review of the elusive bicolored iris Snouted Treefrogs (Anura: Hylidae:Scinax uruguayus group)
[This corrects the article DOI: 10.1371/journal.pone.0222131.].
Journal Article
Ongoing declines for the world’s amphibians in the face of emerging threats
Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.
Journal Article
Efficient Expression of Functional
Human ([alpha]6[beta]2)([alpha]4[beta]2)[beta]3 nicotinic acetylcholine receptors (AChRs) are essential for addiction to nicotine and a target for drug development for smoking cessation. Expressing this complex AChR is difficult, but has been achieved using subunit concatamers. In order to determine what limits expression of [alpha]6* AChRs and to efficiently express [alpha]6* AChRs using free subunits, we investigated expression of the simpler ([alpha]6[beta]2).sub.2 [beta]3 AChR. The concatameric form of this AChR assembles well, but is transported to the cell surface inefficiently. Various chimeras of [alpha]6 with the closely related [alpha]3 subunit increased expression efficiency with free subunits and produced pharmacologically equivalent functional AChRs. A chimera in which the large cytoplasmic domain of [alpha]6 was replaced with that of [alpha]3 increased assembly with [beta]2 subunits and transport of AChRs to the oocyte surface. Another chimera replacing the unique methionine 211 of [alpha]6 with leucine found at this position in transmembrane domain 1 of [alpha]3 and other [alpha] subunits increased assembly of mature subunits containing [beta]3 subunits within oocytes. Combining both [alpha]3 sequences in an [alpha]6 chimera increased expression of functional ([alpha]6[beta]2).sub.2 [beta]3 AChRs to 12-fold more than with concatamers. This is pragmatically useful, and provides insights on features of [alpha]6 subunit structure that limit its expression in transfected cells.
Journal Article
Efficient Expression of Functional .sub.2beta3 AChRs in Xenopus Oocytes from Free Subunits Using Slightly Modified alpha6 Subunits
Human ([alpha]6[beta]2)([alpha]4[beta]2)[beta]3 nicotinic acetylcholine receptors (AChRs) are essential for addiction to nicotine and a target for drug development for smoking cessation. Expressing this complex AChR is difficult, but has been achieved using subunit concatamers. In order to determine what limits expression of [alpha]6* AChRs and to efficiently express [alpha]6* AChRs using free subunits, we investigated expression of the simpler ([alpha]6[beta]2).sub.2 [beta]3 AChR. The concatameric form of this AChR assembles well, but is transported to the cell surface inefficiently. Various chimeras of [alpha]6 with the closely related [alpha]3 subunit increased expression efficiency with free subunits and produced pharmacologically equivalent functional AChRs. A chimera in which the large cytoplasmic domain of [alpha]6 was replaced with that of [alpha]3 increased assembly with [beta]2 subunits and transport of AChRs to the oocyte surface. Another chimera replacing the unique methionine 211 of [alpha]6 with leucine found at this position in transmembrane domain 1 of [alpha]3 and other [alpha] subunits increased assembly of mature subunits containing [beta]3 subunits within oocytes. Combining both [alpha]3 sequences in an [alpha]6 chimera increased expression of functional ([alpha]6[beta]2).sub.2 [beta]3 AChRs to 12-fold more than with concatamers. This is pragmatically useful, and provides insights on features of [alpha]6 subunit structure that limit its expression in transfected cells.
Journal Article
Biogeographic Analysis Reveals Ancient Continental Vicariance and Recent Oceanic Dispersal in Amphibians
Amphibia comprises over 7000 extant species distributed in almost every ecosystem on every continent except Antarctica. Most species also show high specificity for particular habitats, biomes, or climatic niches, seemingly rendering long-distance dispersal unlikely. Indeed, many lineages still seem to show the signature of their Pangaean origin, approximately 300 Ma later. To date, no study has attempted a large-scale historical-biogeographic analysis of the group to understand the distribution of extant lineages. Here, I use an updated chronogram containing 3309 species (~45% of extant diversity) to reconstruct their movement between 12 global ecoregions. I find that Pangaean origin and subsequent Laurasian and Gondwanan fragmentation explain a large proportion of patterns in the distribution of extant species. However, dispersal during the Cenozoic, likely across land bridges or short distances across oceans, has also exerted a strong influence. Finally, there are at least three strongly supported instances of long-distance oceanic dispersal between former Gondwanan landmasses during the Cenozoic. Extinction from intervening areas seems to be a strong factor in shaping present-day distributions. Dispersal and extinction from and between ecoregions are apparently tied to the evolution of extraordinarily adaptive expansion-oriented phenotypes that allow lineages to easily colonize new areas and diversify, or conversely, to extremely specialized phenotypes or heavily relictual climatic niches that result in strong geographic localization and limited diversification.
Journal Article
Phase II trial of radiotherapy plus Huachansu in elderly or chemotherapy-ineligible patients with locally advanced esophageal squamous cell carcinoma
Abstract
Background
Preclinical studies have demonstrated that Huachansu, a traditional Chinese medicine derived from toad venom, exhibits radiosensitizing properties. This study aimed to explore whether Huachansu plus radiotherapy can improve the tumor control in elderly and chemotherapy-ineligible patients with locally advanced esophageal squamous cell carcinoma (ESCC).
Methods
Eligible patients were randomly assigned at a 1:1 ratio to receive either radiotherapy alone (RT) or combined Huachansu and radiotherapy (Huachansu + RT). The primary endpoint was locoregional control, and the secondary endpoints were overall survival (OS), progression-free survival (PFS), and treatment-related toxicities.
Results
From September 2015 to January 2020, 126 patients who met the eligibility criteria were randomly assigned to the Huachansu + RT group (n = 65) or the RT alone group (n = 61) from three hospitals. At a median follow-up of 64.8 months (IQR 37.8-78.3), the median locoregional control time was 12.9 months (95% CI 0-27.0) in the Huachansu + RT group and 22.0 months (95% CI 0-52.0) in the RT alone group (HR = 1.35, 95% CI 0.82-2.22; P = .235). The median OS time was 15.0 months (95% CI 10.3-19.7) in the Huachansu + RT group and 17.2 months (95% CI 11.3-23.1) in the RT alone group (HR 1.03 95% CI 0.71-1.51 P = .868). There was no significant difference between the two groups in the incidence of acute grade 3 or higher adverse events.
Conclusions
Compared with radiotherapy alone, concurrent radiotherapy with Huachansu injection did not improve the locoregional control rate or survival rate in elderly patients or chemotherapy-ineligible patients with locally advanced ESCC. The trial is registered with ClinicalTrials.org, NCT02647125.
Journal Article
Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama
Amphibian populations around the world are experiencing unprecedented declines attributed to a chytrid fungal pathogen, Batrachochytriumdendrobatidis. Despitetheseverity ofthecrisis, quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable as a result of the lack of equivalent data collected before and following disease outbreak. We present a community-level assessment combining long-term field surveys and DNA barcode data describing changes in abundance and evolutionary diversity within the amphibian community of El Copé, Panama, following a disease epidemic and mass-mortality event. The epidemic reduced taxonomic, lineage, and phylogenetic diversity similarly. We discovered that 30 species were lost, including five undescribed species, representing 41% of total amphibian lineage diversity in El Copé. These extirpations represented 33% of the evolutionary history of amphibians within the community, and variation in the degree of population loss and decline among species was random with respect to the community phylogeny. Our approach provides a fast, economical, and informative analysis of loss in a community whether measured by species or phylogenetic diversity.
Journal Article
Amphibian Declines
This benchmark volume documents in comprehensive detail a major environmental crisis: rapidly declining amphibian populations and the disturbing developmental problems that are increasingly prevalent within many amphibian species. Horror stories on this topic have been featured in the scientific and popular press over the past fifteen years, invariably asking what amphibian declines are telling us about the state of the environment. Are declines harbingers of devastated ecosystems or simply weird reflections of a peculiar amphibian world? This compendium—presenting new data, reviews of current literature, and comprehensive species accounts—reinforces what scientists have begun to suspect, that amphibians are a lens through which the state of the environment can be viewed more clearly. And, that the view is alarming and presages serious concerns for all life, including that of our own species. The first part of this work consists of more than fifty essays covering topics from the causes of declines to conservation, surveys and monitoring, and education. The second part consists of species accounts describing the life history and natural history of every known amphibian species in the United States.
eBook