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1.
Nature ; 605(7909): 285-290, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35477765

RESUMO

Comprehensive assessments of species' extinction risks have documented the extinction crisis1 and underpinned strategies for reducing those risks2. Global assessments reveal that, among tetrapods, 40.7% of amphibians, 25.4% of mammals and 13.6% of birds are threatened with extinction3. Because global assessments have been lacking, reptiles have been omitted from conservation-prioritization analyses that encompass other tetrapods4-7. Reptiles are unusually diverse in arid regions, suggesting that they may have different conservation needs6. Here we provide a comprehensive extinction-risk assessment of reptiles and show that at least 1,829 out of 10,196 species (21.1%) are threatened-confirming a previous extrapolation8 and representing 15.6 billion years of phylogenetic diversity. Reptiles are threatened by the same major factors that threaten other tetrapods-agriculture, logging, urban development and invasive species-although the threat posed by climate change remains uncertain. Reptiles inhabiting forests, where these threats are strongest, are more threatened than those in arid habitats, contrary to our prediction. Birds, mammals and amphibians are unexpectedly good surrogates for the conservation of reptiles, although threatened reptiles with the smallest ranges tend to be isolated from other threatened tetrapods. Although some reptiles-including most species of crocodiles and turtles-require urgent, targeted action to prevent extinctions, efforts to protect other tetrapods, such as habitat preservation and control of trade and invasive species, will probably also benefit many reptiles.


Assuntos
Conservação dos Recursos Naturais , Extinção Biológica , Répteis , Jacarés e Crocodilos , Anfíbios , Animais , Biodiversidade , Aves , Mamíferos , Filogenia , Répteis/classificação , Medição de Risco , Tartarugas
2.
PLoS Pathog ; 19(1): e1011070, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36603024

RESUMO

Zika virus (ZIKV) infects fetal neural progenitor cells (NPCs) causing severe neurodevelopmental disorders in utero. Multiple pathways involved in normal brain development are dysfunctional in infected NPCs but how ZIKV centrally reprograms these pathways remains unknown. Here we show that ZIKV infection disrupts subcellular partitioning of host transcripts critical for neurodevelopment in NPCs and functionally link this process to the up-frameshift protein 1 (UPF1). UPF1 is an RNA-binding protein known to regulate decay of cellular and viral RNAs and is less expressed in ZIKV-infected cells. Using infrared crosslinking immunoprecipitation and RNA sequencing (irCLIP-Seq), we show that a subset of mRNAs loses UPF1 binding in ZIKV-infected NPCs, consistent with UPF1's diminished expression. UPF1 target transcripts, however, are not altered in abundance but in subcellular localization, with mRNAs accumulating in the nucleus of infected or UPF1 knockdown cells. This leads to diminished protein expression of FREM2, a protein required for maintenance of NPC identity. Our results newly link UPF1 to the regulation of mRNA transport in NPCs, a process perturbed during ZIKV infection.


Assuntos
Células-Tronco Neurais , Infecção por Zika virus , Zika virus , Humanos , Encéfalo/metabolismo , Encéfalo/virologia , Células-Tronco Neurais/virologia , RNA Helicases/genética , RNA Helicases/metabolismo , Transativadores/metabolismo , Replicação Viral , Zika virus/fisiologia , Infecção por Zika virus/genética
3.
Mol Phylogenet Evol ; 197: 108104, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38750676

RESUMO

Barking geckos (genus Ptenopus) are terrestrial, burrowing lizards endemic to southern Africa, currently with three recognised species. Two species are range-restricted (P. kochi and P. carpi) and display clear differences in substrate preference (soft sand vs. hard gravel). The third and most widespread species, P. garrulus, occurs on a variety of substrates of differing hardness, across potential geographic barriers, and over a steep climatic gradient. Variations in morphology and advertisement calls indicates that P. garrulus may be a species complex. Two subspecies of P. garrulus are currently recognised: P. g. maculatus and P. g. garrulus. To investigate species boundaries, we produced the first comprehensive phylogeny for the genus. We used a novel application of multiple regression on matrices models to assess multiple environmental drivers of diversification, as contrasted to isolation by distance. We show that P. kochi, P. carpi, and P. g. garrulus are valid species, but that P. g. maculatus is a paraphyletic complex of five previously unrecognised taxa. Specialisation onto different substrates was likely the main driver of divergence, with parapatric occurrence of two to four clades occurring at each of the three substrate transition zones identified a priori. The region encompasses diverse bioclimatic regions and potential geographic barriers, and these likely played a role in some divergence events.


Assuntos
Lagartos , Filogenia , Animais , Lagartos/genética , Lagartos/classificação , DNA Mitocondrial/genética , Especiação Genética , Análise de Sequência de DNA , África Austral , Teorema de Bayes , Modelos Genéticos
4.
Glob Chang Biol ; 30(1)2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273552

RESUMO

We created a database of lost and rediscovered tetrapod species, identified patterns in their distribution and factors influencing rediscovery. Tetrapod species are being lost at a faster rate than they are being rediscovered, due to slowing rates of rediscovery for amphibians, birds and mammals, and rapid rates of loss for reptiles. Finding lost species and preventing future losses should therefore be a conservation priority. By comparing the taxonomic and spatial distribution of lost and rediscovered tetrapod species, we have identified regions and taxa with many lost species in comparison to those that have been rediscovered-our results may help to prioritise search effort to find them. By identifying factors that influence rediscovery, we have improved our ability to broadly distinguish the types of species that are likely to be found from those that are not (because they are likely to be extinct). Some lost species, particularly those that are small and perceived to be uncharismatic, may have been neglected in terms of conservation effort, and other lost species may be hard to find due to their intrinsic characteristics and the characteristics of the environments they occupy (e.g. nocturnal species, fossorial species and species occupying habitats that are more difficult to survey such as wetlands). These lost species may genuinely await rediscovery. However, other lost species that possess characteristics associated with rediscovery (e.g. large species) and that are also associated with factors that negatively influence rediscovery (e.g. those occupying small islands) are more likely to be extinct. Our results may foster pragmatic search protocols that prioritise lost species likely to still exist.


Assuntos
Ecossistema , Extinção Biológica , Animais , Anfíbios , Áreas Alagadas , Mamíferos , Conservação dos Recursos Naturais/métodos , Espécies em Perigo de Extinção , Biodiversidade
5.
Chem Senses ; 492024 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-38421250

RESUMO

Many common chemotherapeutics produce disruptions in the sense of taste which can lead to loss of appetite, nutritional imbalance, and reduced quality of life, especially if taste loss persists after treatment ends. Cyclophosphamide (CYP), an alkylating chemotherapeutic agent, affects taste sensitivity through its cytotoxic effects on mature taste receptor cells (TRCs) and on taste progenitor cell populations, retarding the capacity to replace TRCs. Mechanistic studies have focused primarily on taste cells, however, taste signaling requires communication between TRCs and the gustatory nerve fibers that innervate them. Here, we evaluate cyclophosphamide's effects on the peripheral gustatory nerve fibers that innervate the taste buds. Following histological analysis of tongue tissues, we find that CYP reduces innervation within the fungiform and circumvallates taste buds within 4 days after administration. To better understand the dynamics of the denervation process, we used 2-photon intravital imaging to visualize the peripheral gustatory nerve fibers within individual fungiform taste buds up to 20 days after CYP treatment. We find that gustatory fibers retract from the taste bud properly but are maintained within the central papilla core. These data indicate that in addition to TRCs, gustatory nerve fibers are also affected by CYP treatment. Because the connectivity between TRCs and gustatory neurons must be re-established for proper function, gustatory fibers should continue to be included in future studies to understand the mechanisms leading to chemotherapy-induced persistent taste loss.


Assuntos
Ageusia , Papilas Gustativas , Animais , Camundongos , Papilas Gustativas/fisiologia , Qualidade de Vida , Língua , Ciclofosfamida/farmacologia , Paladar
6.
Behav Sleep Med ; : 1-15, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38850019

RESUMO

OBJECTIVES: The main objectives of the current paper were to examine the feasibility, acceptability, and adherence of a remotely delivered intervention consisting of mindfulness-based stress reduction plus prenatal sleep classes (MBSR+PS) compared with treatment as usual (TAU). METHOD: In this pilot randomized controlled trial, 52 pregnant women with poor sleep quality were randomized to MBSR+PS or TAU. MBSR was delivered through eight weekly 2.5-hour sessions, and PS was delivered through eight weekly 30-minute sessions. PS content drew material from cognitive behavioral therapy for insomnia tailored for the perinatal period and from a mindfulness- and acceptance-based lens. Participants completed endpoint measures 10-12 weeks after randomization. RESULTS: We surpassed all acceptability targets, including the percentage of eligible participants willing to be randomized (96%), percentage of participants who initiated treatment (88%), and satisfaction scores (Client Satisfaction Questionnaire-8 score M = 28.04, SD = 3.6). We surpassed all feasibility targets, including our enrollment target, retention rate (92%), and measure completion (96%). Finally, we surpassed adherence targets, including MBSR and PS session attendance (≥80%). Though sleep outcomes were exploratory, increases in sleep efficiency were greater in the MBSR+PS group relative to TAU (SMD=.68). CONCLUSIONS: Patient-reported poor sleep quality during pregnancy has high public health significance because it is common, consequential, and under-treated. The current feasibility and acceptability data for using remotely delivered MBSR and PS to improve prenatal sleep quality are encouraging and warranting future research that is sufficiently powered and designed to provide efficacy data. In addition, exploratory sleep outcomes offer preliminary evidence that this sleep program may improve sleep efficiency during pregnancy.

7.
J Infect Dis ; 2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-38019956

RESUMO

BACKGROUND: A controlled human infection model for assessing tuberculosis (TB) immunity can accelerate new vaccine development. METHODS: In this phase 1 dose escalation trial, 92 healthy adults received a single intradermal injection of 2 × 106 to 16 × 106 colony-forming units of Bacillus Calmette-Guérin (BCG). The primary endpoints were safety and BCG shedding as measured by quantitative polymerase chain reaction, colony-forming unit plating, and MGIT BACTEC culture. RESULTS: Doses up to 8 × 106 were safe, and there was evidence for increased BCG shedding with dose escalation. The MGIT time-to-positivity assay was the most consistent and precise measure of shedding. Power analyses indicated that 10% differences in MGIT time to positivity (area under the curve) could be detected in small cohorts (n = 30). Potential biomarkers of mycobacterial immunity were identified that correlated with shedding. Transcriptomic analysis uncovered dose- and time-dependent effects of BCG challenge and identified a putative transcriptional TB protective signature. Furthermore, we identified immunologic and transcriptomal differences that could represent an immune component underlying the observed higher rate of TB disease incidence in males. CONCLUSIONS: The safety, reactogenicity, and immunogenicity profiles indicate that this BCG human challenge model is feasible for assessing in vivo TB immunity and could facilitate the vaccine development process. CLINICAL TRIALS REGISTRATION: NCT01868464 (ClinicalTrials.gov).

8.
Mol Phylogenet Evol ; 175: 107578, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35809854

RESUMO

Molecular phylogenetics and the application of species delimitation methods have proven useful in addressing limitations associated with morphology based taxonomy and have highlighted the inconsistencies in the current taxonomy for many groups. For example, the genus Chamaeleo, which comprises 14 species with large distributions across mainland Africa and parts of Eurasia, exhibits relatively minor phenotypic differentiation between species, leading to speculation regarding the presence of cryptic diversity in the genus. Therefore, the aims of the present study were to construct a robust and comprehensive phylogeny of the genus and highlight potential species-level cryptic diversity. Additionally, we sought to ascertain the most likely biogeographic origin of the genus and understand its spatio-temporal diversification. Accordingly, we made use of species delimitation methods (Bayesian and divergence based) to investigate the extent of cryptic diversity in Chamaeleo, and applied an ancestral area reconstruction to examine the biogeographic origin of the group. Our phylogenetic analyses suggested the presence of at least 18 taxa within Chamaeleo. Notably, three taxa could be recognised within C. dilepis, none of which are equivalent in context with any of the currently described subspecies. There were also three taxa within C. gracilis and two within C. anchietae. The single available tissue specimen identified as C. necasi was embedded within the C. gracilis clade. Our ancestral area reconstruction points to a southern African/Zambezian origin for Chamaeleo, with diversification beginning during the cooling and aridification of Africa that characterised the Oligocene Epoch, ca. 34-23 Mya (Million years ago). Species-level diversification began in the Miocene Epoch (ca. 23-5 Mya), possibly tracking the aridification that triggered the shift from forest to more open, mesic savanna for most clades, but with tectonic events influencing speciation in a Palearctic clade. These findings lay the foundation for a future integrative taxonomic re-evaluation of Chamaeleo, which will be supported with additional lines of evidence before implementing any taxonomic changes.


Assuntos
Florestas , África Austral , Teorema de Bayes , Filogenia , Filogeografia
9.
Ecol Appl ; 32(2): e2502, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34873777

RESUMO

Detecting occupied sites of rare species, and estimating the probability that all occupied sites are known within a given area, are desired outcomes for many ecological or conservation projects. Examples include managing all occupied sites of a threatened species or eradicating an emerging invader. Occupied sites may remain undetected because (1) sites where the species potentially occurs had not been searched, and (2) the species could have been overlooked in the searched sites. For rare species, available data are typically scant, making it difficult to predict sites where the species probably occurs or to estimate detection probability in the searched sites. Using the critically endangered Rose's mountain toadlet (Capensibufo rosei), known from only two localities, we outline an iterative process aimed at estimating the probability that any unknown occupied sites remain and maximizing the chance of finding them. This includes fitting a species distribution model to guide sampling effort, testing model accuracy and sampling efficacy using the occurrence of more common proxy species, and estimating detection probability using sites of known presence. The final estimate of the probability that all occupied sites were found incorporates the uncertainties of uneven distribution, relative area searched, and detection probability. Our results show that very few occupied sites of C. rosei are likely to remain undetected. We also show that the probability of an undetected occupied site remaining will always be high for large unsearched areas of potential occurrence, but can be low for smaller areas intended for targeted management interventions. Our approach is especially useful for assessing uncertainty in species occurrences, planning the required search effort needed to reduce probability of unknown occurrence to desired levels, and identifying priority areas for further searches or management interventions.


Assuntos
Espécies em Perigo de Extinção , Animais , Probabilidade
10.
Infect Immun ; 89(7): e0073820, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-33941576

RESUMO

Trypanosoma cruzi is the intracellular parasite of Chagas disease, a chronic condition characterized by cardiac and gastrointestinal morbidity. Protective immunity requires CD4+ T cells, and Th1 cells and gamma interferon (IFN-γ) are important players in host defense. More recently, Th17 cells and interleukin 17A (IL-17A) have been shown to exert protective functions in systemic T. cruzi infection. However, it remains unclear whether Th17 cells and IL-17A protect in the mucosa, the initial site of parasite invasion in many human cases. We found that IL-17RA knockout (KO) mice are highly susceptible to orogastric infection, indicating an important function for this cytokine in mucosal immunity to T. cruzi. To investigate the specific role of Th17 cells for mucosal immunity, we reconstituted RAG1 KO mice with T. cruzi-specific T cell receptor transgenic Th17 cells prior to orogastric T. cruzi challenges. We found that Th17 cells provided protection against gastric mucosal T. cruzi infection, indicated by significantly lower stomach parasite burdens. In vitro macrophage infection assays revealed that protection by Th17 cells is reduced with IL-17A neutralization or reversed by loss of macrophage NADPH oxidase activity. Consistently with this, mice lacking functional NADPH oxidase were not protected by Th17 cell transfer. These data are the first report that Th17 cells protect against mucosal T. cruzi infection and identify a novel protective mechanism involving the induction of NADPH oxidase activity by IL-17A. These studies provide important insights for Chagas vaccine development and, more broadly, increase our understanding of the diverse roles of Th17 cells in host defense.


Assuntos
Doença de Chagas/imunologia , Mucosa Gástrica/imunologia , Mucosa Gástrica/parasitologia , Interações Hospedeiro-Parasita/imunologia , Imunidade nas Mucosas , Células Th17/imunologia , Trypanosoma cruzi/imunologia , Animais , Doença de Chagas/metabolismo , Doença de Chagas/parasitologia , Modelos Animais de Doenças , Interleucina-17/genética , Interleucina-17/metabolismo , Ativação Linfocitária/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/parasitologia , Camundongos , Camundongos Knockout , NADPH Oxidases/metabolismo , Células Th17/metabolismo
11.
Biochemistry ; 58(6): 509-513, 2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30584764

RESUMO

Cd2+ and Pb2+ are xenobiotic heavy metal ions that use ionic mimicry to interfere with the cellular function of biomacromolecules. Using a combination of SAXS, electron microscopy, FRET, and solution NMR spectroscopy, we demonstrate that treatment with Cd2+ and Pb2+ causes self-assembly of protein kinase C regulatory domains that peripherally associate with membranes. The self-assembly process successfully competes with ionic mimicry and is mediated by conserved protein regions that are distinct from the canonical Ca2+-binding motifs of protein kinase C. The ability of protein oligomers to interact with anionic membranes is enhanced compared to the monomeric species. Our findings suggest that metal-ion-dependent peripheral membrane domains can be utilized for generating protein-metal-ion nanoclusters and serve as biotemplates for the design of sequestration agents.


Assuntos
Cádmio/farmacologia , Membrana Celular/metabolismo , Chumbo/farmacologia , Nanocompostos/química , Proteína Quinase C/química , Proteína Quinase C/metabolismo , Membrana Celular/efeitos dos fármacos , Humanos , Conformação Proteica , Domínios Proteicos
12.
Mol Phylogenet Evol ; 130: 357-365, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30366085

RESUMO

The African green and bush snakes of the genus Philothamnus currently comprises 21 species and three subspecies and occurs throughout sub-Saharan Africa. The genus has been the subject of previous taxonomic revisions based on traditional morphological characters and limited genetic assessment, and may not reflect their evolutionary history. Indeed, previous findings based on phylogenetics show discordant results of interspecific relationships and question the monophyly of the genus, although taxon sampling has been limited to date. We investigated phylogenetic affinities within Philothamnus with more inclusive genetic and geographical sampling, with the aim of better understanding their evolutionary history, so that future taxonomic revision of Philothamnus can be better informed. Species relationships were examined within a phylogenetic context and sampling included 133 ingroup samples from 16 taxa. Phylogenies were constructed in Bayesian and likelihood frameworks using three mitochondrial (16S, cyt b and ND4) and two nuclear (c-mos and RAG1) markers. Competing hypotheses relating to the monophyly of the genus were tested with a Shimodaira-Hasegawa test. To examine species boundaries, Bayesian General Mixed Yule-Coalescent Model and multi-rate Poisson Tree Processes analyses were conducted. In addition, a barcoding approach was used to further clarify species-level relationships by comparing frequency distributions between intra- and interspecific sequence divergence. The genus was recovered as monophyletic; however, species-delimitation results suggest that the current taxonomy does not reflect the evolutionary history of this group. For example, Philothamnus s. semivariegatus is paraphyletic, with at least four distinct clades. Philothamnus carinatus consists of two cryptic (sister) lineages from Central and West Africa that are deeply divergent, suggesting a long history of isolation between those regions. Furthermore, the subspecies P. n. natalensis and P. n. occidentalis show strong support for species-level divergence, which reflects their morphological and ecological differences. Accordingly, we elevate P. occidentalisnov. comb. to a full species. A fully informed taxonomic revision of these taxa will require additional morphological and ecological data for corroboration, but it seems that the morphological characters (e.g. scalation, dentition) used to describe these species to date are labile within and between species. This most likely has clouded our understanding of the species boundaries within the genus. Our phylogeny and species-delimitation analyses should provide a sounder framework for taxonomy, but may also prove useful toward understanding the morphological adaptations of these species to their respective habitats.


Assuntos
Colubridae/genética , Variação Genética , África Ocidental , Animais , Teorema de Bayes , Geografia , Funções Verossimilhança , Filogenia , Análise de Sequência de DNA , Especificidade da Espécie
13.
Clin Endocrinol (Oxf) ; 90(4): 553-561, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30614551

RESUMO

OBJECTIVE: Macronutrient regulation of hyperphagia and adiposity in Prader-Willi syndrome (PWS) is poorly understood. We compared fasting and postprandial concentrations of hormones and metabolites in eight PWS children (age 9-18 years) fed, in random order, low carbohydrate, high-fat (LC, 15% carb; 65% fat; 20% protein) and low-fat, high carbohydrate (LF, 65% carb, 15% fat, 20% protein) diets matched for calories and protein. METHODS: Participants were randomized to consume either the LC or LF diet during a first hospital admission and the second diet during a subsequent admission. Blood samples were obtained after overnight fasting and 1 hour after a mixed meal. RESULTS: Relative to subjects consuming the LF diet, subjects consuming the LC diet had: lower postprandial insulin concentrations (P = 0.02); higher fasting GLP-1 AND GIP concentrations and increased postprandial GLP-1 (P < 0.02); reduced ratio of fasting ghrelin to GLP-1 (P = 0.0078); increased FFA and fatty acid oxidation, as assessed by concentrations of even-chain acylcarnitines (P < 0.001); lower fasting TG and TG/HDL ratio (P < 0.01); and higher concentrations of branch chain amino acids (P < 0.01). There were no changes in glucose, PYY, or adiponectin. CRP, AST and ALT were all higher (P < 0.01) on the LC diet. CONCLUSIONS: Increases in GLP-1 with low carbohydrate feeding and reductions in the ratio of ghrelin to GLP-1 might limit food intake and improve glycaemic control in PWS. Other potential benefits of carbohydrate restriction may include fat mobilization and oxidation and reductions in the TG/HDL ratio, a marker of insulin resistance. However, increases in CRP, AST and ALT necessitate longer-term studies of low carbohydrate efficacy and safety.


Assuntos
Síndrome de Prader-Willi/metabolismo , Adiposidade/fisiologia , Adolescente , Aminoácidos/sangue , Aminoácidos/metabolismo , Glicemia/metabolismo , Criança , Jejum/sangue , Feminino , Peptídeo 1 Semelhante ao Glucagon , Humanos , Insulina/sangue , Insulina/metabolismo , Resistência à Insulina , Masculino , Peptídeo YY/sangue , Peptídeo YY/metabolismo , Síndrome de Prader-Willi/sangue
14.
Am Nat ; 191(2): 250-258, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29351012

RESUMO

Age-specific survival and reproduction are closely linked to fitness and therefore subject to strong selection that typically limits their variability within species. Furthermore, adult survival rate in vertebrate populations is typically less variable over time than other life-history traits, such as fecundity or recruitment. Hence, adult survival is often conserved within a population over time, compared to the variation in survival found across taxa. In stark contrast to this general pattern, we report evidence of extreme short-term variation of adult survival in Rose's mountain toadlet (Capensibufo rosei), which is apparently climate induced. Over 7 years, annual survival rate varied between 0.04 and 0.92, and 94% of this variation was explained by variation in breeding-season rainfall. Preliminary results suggest that this variation reflects adaptive life-history plasticity to a degree thus far unrecorded for any vertebrate, rather than direct rainfall-induced mortality. In wet years, these toads appeared to achieve increased reproduction at the expense of their own survival, whereas in dry years, their survival increased at the expense of reproduction. Such environmentally induced plasticity may reflect a diversity of life-history strategies not previously appreciated among vertebrates.


Assuntos
Adaptação Fisiológica , Bufonidae/fisiologia , Características de História de Vida , Chuva , Reprodução , Animais , Feminino , Masculino , África do Sul
15.
Mol Phylogenet Evol ; 122: 125-141, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29199108

RESUMO

Several biogeographic barriers in the Central African highlands have reduced gene flow among populations of many terrestrial species in predictable ways. Yet, a comprehensive understanding of mechanisms underlying species divergence in the Afrotropics can be obscured by unrecognized levels of cryptic diversity, particularly in widespread species. We implemented a multilocus phylogeographic approach to examine diversity within the widely distributed Central African pygmy chameleon, Rhampholeon boulengeri. Gene-tree analyses coupled with a comparative coalescent-based species delimitation framework revealed R. boulengeri as a complex of at least six genetically distinct species. The spatiotemporal speciation patterns for these cryptic species conform to general biogeographic hypotheses supporting vicariance as the main factor behind patterns of divergence in the Albertine Rift, a biodiversity hotspot in Central Africa. However, we found that parapatric species and sister species inhabited adjacent habitats, but were found in largely non-overlapping elevational ranges in the Albertine Rift, suggesting that differentiation in elevation was also an important mode of divergence. The phylogeographic patterns recovered for the genus-level phylogeny provide additional evidence for speciation by isolation in forest refugia, and dating estimates indicated that the Miocene was a significant period for this diversification. Our results highlight the importance of investigating cryptic diversity in widespread species to improve understanding of diversification patterns in environmentally diverse regions such as the montane Afrotropics.


Assuntos
Biodiversidade , Lagartos/classificação , África Central , Animais , DNA/química , DNA/isolamento & purificação , DNA/metabolismo , DNA Mitocondrial/genética , Ecossistema , Fluxo Gênico , Lagartos/genética , Filogenia , Filogeografia , Análise de Sequência de DNA
16.
J Pathol ; 242(3): 371-383, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28444909

RESUMO

Small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT) is a rare but aggressive and untreatable malignancy affecting young women. We and others recently discovered that SMARCA4, a gene encoding the ATPase of the SWI/SNF chromatin-remodelling complex, is the only gene recurrently mutated in the majority of SCCOHT. The low somatic complexity of SCCOHT genomes and the prominent role of the SWI/SNF chromatin-remodelling complex in transcriptional control of genes suggest that SCCOHT cells may rely on epigenetic rewiring for oncogenic transformation. Herein, we report that approximately 80% (19/24) of SCCOHT tumour samples have strong expression of the histone methyltransferase EZH2 by immunohistochemistry, with the rest expressing variable amounts of EZH2. Re-expression of SMARCA4 suppressed the expression of EZH2 in SCCOHT cells. In comparison to other ovarian cell lines, SCCOHT cells displayed hypersensitivity to EZH2 shRNAs and two selective EZH2 inhibitors, GSK126 and EPZ-6438. EZH2 inhibitors induced cell cycle arrest, apoptosis, and cell differentiation in SCCOHT cells, along with the induction of genes involved in cell cycle regulation, apoptosis, and neuron-like differentiation. EZH2 inhibitors suppressed tumour growth and improved the survival of mice bearing SCCOHT xenografts. Therefore, our data suggest that loss of SMARCA4 creates a dependency on the catalytic activity of EZH2 in SCCOHT cells and that pharmacological inhibition of EZH2 is a promising therapeutic strategy for treating this disease. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Assuntos
Carcinoma de Células Pequenas/enzimologia , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Histona-Lisina N-Metiltransferase/metabolismo , Hipercalcemia/enzimologia , Neoplasias Ovarianas/enzimologia , Animais , Apoptose/fisiologia , Carcinoma Epitelial do Ovário , Pontos de Checagem do Ciclo Celular/fisiologia , Linhagem Celular Tumoral , Transformação Celular Neoplásica , DNA Helicases/deficiência , Regulação para Baixo , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Feminino , Histona Metiltransferases , Humanos , Transplante de Neoplasias , Neoplasias Epiteliais e Glandulares/enzimologia , Proteínas Nucleares/deficiência , Fatores de Transcrição/deficiência , Transplante Heterólogo , Células Tumorais Cultivadas , Regulação para Cima
17.
Oecologia ; 188(1): 139-147, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29869020

RESUMO

Enemy release often is invoked to explain the success of invasive plants: an invader benefits from reduced attack as it escapes specialized enemies through the invasion process. Enemy release typically is thought of as occurring at large geographic scales, but local-scale interactions may also be important for invader establishment and success. Furthermore, most tests of local enemy release have been conducted over a single year even though release may be a transient phenomenon, especially at small scales. In this study, we used a multi-year field experiment to investigate whether locally isolated populations of the noxious non-native weed Cirsium arvense benefit from reduced levels of aboveground damage, and whether any initial advantage is lost over subsequent growing seasons. Populations of C. arvense were grown in plots at set distances from established source populations for 4 years. In the first year of the experiment, folivory significantly declined with host isolation, but damage from specialist stem gallers and seed predators did not. However, in subsequent years of observation, folivores began colonizing isolated C. arvense populations while stem gallers exhibited very slow colonization of more isolated plots; seed predation showed no pattern with distance in any year. Local enemy escape did not result in increased plant performance, which instead negatively correlated with degree of isolation. Nonetheless, our results stress the importance of multi-year observations in tests of enemy release, since the herbivory patterns initially observed often changed within subsequent years depending on the dispersal ability and biology of the causal organism involved.


Assuntos
Cirsium , Herbivoria , Plantas Daninhas , Estações do Ano
18.
Mol Phylogenet Evol ; 114: 261-270, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28684366

RESUMO

Ecological niche models (ENMs) have been used in a wide range of ecological and evolutionary studies. In biogeographic studies these models have, among other things, helped in the discovery of new allopatric populations, and even new species. However, small sample sizes and questionable taxonomic delimitation can challenge models, often decreasing their accuracy. Herein we examine the sensitivity of ENMs to the addition of new, geographically isolated populations, and the impact of applying different taxonomic delimitations. The East African reed frog Hyperolius substriatus Ahl, 1931 was selected as a case study because it has been the subject of previous ENM predictions. Our results suggest that addition of new data and reanalysis of species lineages of H. substriatus improved our understanding of the evolutionary history of this group of frogs. ENMs provided robust predictions, even when some populations were deliberately excluded from the models. Splitting the lineages based on genetic relationships and analysing the ENMs separately provided insights about the biogeographical processes that led to the current distribution of H. substriatus.


Assuntos
Anuros/classificação , África Oriental , Animais , Anuros/genética , Evolução Biológica , DNA/química , DNA/isolamento & purificação , DNA/metabolismo , Ecologia , Fluxo Gênico , Ligação Genética , Filogenia , Filogeografia , Pró-Proteína Convertases/classificação , Pró-Proteína Convertases/genética , Proteínas Proto-Oncogênicas c-myc/classificação , Proteínas Proto-Oncogênicas c-myc/genética , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
19.
Tetrahedron Lett ; 58(7): 638-641, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-29277842

RESUMO

Herein, we report the first synthesis of chlorinated benzo[b]selenophenes via environmentally friendly electrophilic chlorocyclization reaction using "table salt" as a source of "electrophilic chlorine" and ethanol as a solvent. In addition, the synthesis of diverse halogenated heterocycles, including 3-chloro, 3-bromo and 3-iodo thiophenes, selenophenes, and benzo[b]selenophenes was successfully accomplished under the same environmentally benign reaction conditions. This methodology has several advantages over other previously reported reactions as it employs simple starting compounds, an environmentally friendly solvent, ethanol, and non-toxic inorganic reagents under mild reaction conditions, resulting in the high product yields.

20.
Anaesthesia ; 72(6): 729-736, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28251606

RESUMO

Previous pilot work has established an association between obstructive sleep apnoea and the development of acute postoperative delirium , but it remains unclear to what extent this risk factor is modifiable in the 'real world' peri-operative setting. In a single-blind randomised controlled trial, 135 elderly surgical patients at risk for obstructive sleep apnoea were randomly assigned to receive peri-operative continuous positive airway pressure (CPAP) or routine care. Of the 114 patients who completed the study, 21 (18.4%) experienced delirium. Delirium was equally common in both groups: 21% (12 of 58 subjects) in the CPAP group and 16% (9 of 56 subjects) in the routine care group (OR = 1.36 [95%CI 0.52-3.54], p = 0.53). Delirious subjects were slightly older - mean (SD) age 68.9 (10.7) vs. 64.9 (8.2), p = 0.07 - but had nearly identical pre-operative STOP-Bang scores (4.19 (1.1) versus 4.27 (1.3), p = 0.79). Subjects in the CPAP group used their devices for a median (IQR [range]) of 3 (0.25-5 [0-12]) nights pre-operatively (2.9 (0.1-4.8 [0.0-12.7]) hours per night) and 1 (0-2 [0-2]) nights postoperatively (1.4 (0.0-5.1 [0.0-11.6]) hours per night). Among the CPAP subjects, the residual pre-operative apnoea-hypopnea index had a significant effect on delirium severity (p = 0.0002). Although we confirm that apnoea is associated with postoperative delirium, we did not find that providing a short-course of auto-titrating CPAP affected its likelihood or severity. Voluntary adherence to CPAP is particularly poor during the initiation of therapy.


Assuntos
Anestesia por Condução/métodos , Anestesia Geral/métodos , Artroplastia de Substituição/métodos , Pressão Positiva Contínua nas Vias Aéreas/métodos , Delírio do Despertar/terapia , Assistência Perioperatória/métodos , Complicações Pós-Operatórias/terapia , Apneia Obstrutiva do Sono/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cooperação do Paciente , Estudos Prospectivos , Método Simples-Cego
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