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1.
J Hered ; 2024 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-39248324

RESUMEN

Polyergus kidnapper ants are widely distributed, but relatively uncommon, throughout the Holarctic, spanning an elevational range from sea level to over 3000 m. These species are well known for their obligate social parasitism with various Formica ant species, which they kidnap in dramatic, highly coordinated raids. Kidnapped Formica larvae and pupae become integrated into the Polyergus colony where they develop into adults and perform nearly all of the necessary colony tasks for the benefit of their captors. In California, Polyergus mexicanus is the most widely distributed Polyergus, but recent evidence has identified substantial genetic polymorphism within this species, including genetically divergent lineages associated with the use of different Formica host species. Given its unique behavior and genetic diversity, Polyergus mexicanus plays a critical role in maintaining ecosystem balance by influencing the population dynamics and genetic diversity of its host ant species, Formica, highlighting its conservation value and importance in the context of biodiversity preservation. Here, we present a high-quality genome assembly of P. mexicanus from a sample collected in Plumas County, CA, USA, in the foothills of the central Sierra Nevada. This genome assembly consists of 364 scaffolds spanning 252.31 Mb, with contig N50 of 481,250 kb, scaffold N50 of 10.36 Mb, and BUSCO completeness of 95.4%. We also assembled the genome of the Wolbachia endosymbiont of P. mexicanus - a single, circular contig spanning 1.23 Mb. These genome sequences provide essential resources for future studies of conservation genetics, population genetics, speciation, and behavioral ecology in this charismatic social insect.

2.
J Am Mosq Control Assoc ; 40(2): 102-108, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38547924

RESUMEN

Haiti is home to approximately 11 million people and has a high incidence of vector-borne disease, including more than 70,000 cases of dengue per year. Vector control is difficult in Haiti and adulticide spray of malathion is the main method of control employed during the outbreak of disease although pyrethroids are used in both bed net campaigns and in widely available aerosol cans for personal use. However, limited pathogen or insecticide resistance surveillance data are available for making operational decisions. In this study, we assessed Aedes aegypti from serial surveillance collections from 3 locations for the presence of dengue virus serotypes 1-3 (DENV1-3) by polymerase chain reaction and assessed, by melt curve analysis, samples from 10 locations in 2 departments for the presence of two mutations (V1016I and F1534C), that in combination, are linked to strong pyrethroid insecticide resistance. Only one of the 32 tested pools was positive for the presence of dengue virus. The two knockdown resistance (kdr) mutations were present in all locations. The 1016I mutation frequency varied from 0.29 to 0.91 and was in all sites lower than the 0.58-1.00 frequency of the 1534C mutation. We also observed that the genotype homozygous for both mutations (IICC), which has been linked to strong pyrethroid resistance, varied from 13 to 86% in each population. Notably, 3 locations - Ti Cousin and Christianville in Ouest department and Camp Coq in Nord department had more than 30% of the tested population without the presence of kdr mutations. These results indicate that the kdr markers of pyrethroid resistance are present in Haiti, at high frequency in several locations and, based on previous studies linking kdr genotypes and phenotypic resistance, that operational interventions with pyrethroids are not likely to be as effective as expected.


Asunto(s)
Aedes , Virus del Dengue , Dengue , Resistencia a los Insecticidas , Insecticidas , Mutación , Animales , Aedes/genética , Haití , Resistencia a los Insecticidas/genética , Virus del Dengue/genética , Dengue/transmisión , Insecticidas/farmacología , Mosquitos Vectores/genética , Mosquitos Vectores/efectos de los fármacos , Piretrinas/farmacología
3.
J Exp Biol ; 226(16)2023 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-37497773

RESUMEN

An insect's cuticle is typically covered in a layer of wax prominently featuring various hydrocarbons involved in desiccation resistance and chemical communication. In Argentine ants (Linepithema humile), cuticular hydrocarbons (CHCs) communicate colony identity, but also provide waterproofing necessary to survive dry conditions. Theory suggests different CHC compound classes have functional trade-offs, such that selection for compounds used in communication would compromise waterproofing, and vice versa. We sampled sites of invasive L. humile populations from across California to test whether CHC differences between them can explain differences in their desiccation survival. We hypothesized that CHCs whose abundance was correlated with environmental factors would determine survival during desiccation, but our regression analysis did not support this hypothesis. Interestingly, we found the abundance of most CHCs had a negative correlation with survival, regardless of compound class. We suggest that the CHC differences between L. humile nests in California are insufficient to explain their differential survival against desiccation, and that body mass is a better predictor of desiccation survival at this scale of comparison.


Asunto(s)
Hormigas , Animales , Hormigas/química , Desecación , Hidrocarburos/química , Tamaño Corporal
4.
Vet Parasitol ; 318: 109929, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37080069

RESUMEN

Citrus fruits are consumed all over the world and their by-products are used for animal feed and essential oils production. This study aimed to evaluate the in vitro and in vivo activity of Citrus aurantium var. Dulcis essential oil (CaEO) combined with ABZ against benzimidazole resistant Haemonchus contortus. In vitro egg hatching assays (EHA) were performed using CaEO and ABZ to estimate the effective concentration to achieve 50% egg death (EC50) values and calculate the test essential oil and drug combinations using a simplex-centroid mixture design. These concentrations were used for a second round of EHAs. Sixteen sheep were randomly allocated into two groups and treated with ABZ and the combination of CaEO and ABZ, and faecal egg count reduction tests were performed. In the first round of EHA, CaEO and ABZ showed EC50 values of 0.57 and 0.0048 mg mL-1, respectively. The H. contortus strain used in the study was shown to be highly benzimidazole resistant, with only 1.5% of parasites having susceptible ß-tubulin SNP genotypes. The ABZ reduced the shedding of nematode eggs by 78%, however, its combination with CaEO reduced faecal egg counts by only 9%. The present study is important to highlight the interferences of natural products in anthelmintic metabolism and consequently in drug efficacy.


Asunto(s)
Antihelmínticos , Citrus , Hemoncosis , Haemonchus , Nematodos , Aceites Volátiles , Enfermedades de las Ovejas , Animales , Ovinos , Albendazol/farmacología , Albendazol/uso terapéutico , Aceites Volátiles/farmacología , Aceites Volátiles/uso terapéutico , Antihelmínticos/farmacología , Antihelmínticos/uso terapéutico , Bencimidazoles/farmacología , Heces/parasitología , Enfermedades de las Ovejas/tratamiento farmacológico , Enfermedades de las Ovejas/parasitología , Recuento de Huevos de Parásitos/veterinaria , Resistencia a Medicamentos , Hemoncosis/tratamiento farmacológico , Hemoncosis/veterinaria , Hemoncosis/parasitología
5.
Biotechnol Adv ; 54: 107822, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34461202

RESUMEN

The availability of high-quality genomes and advances in functional genomics have enabled large-scale studies of essential genes in model eukaryotes, including the 'elegant worm' (Caenorhabditis elegans; Nematoda) and the 'vinegar fly' (Drosophila melanogaster; Arthropoda). However, this is not the case for other, much less-studied organisms, such as socioeconomically important parasites, for which functional genomic platforms usually do not exist. Thus, there is a need to develop innovative techniques or approaches for the prediction, identification and investigation of essential genes. A key approach that could enable the prediction of such genes is machine learning (ML). Here, we undertake an historical review of experimental and computational approaches employed for the characterisation of essential genes in eukaryotes, with a particular focus on model ecdysozoans (C. elegans and D. melanogaster), and discuss the possible applicability of ML-approaches to organisms such as socioeconomically important parasites. We highlight some recent results showing that high-performance ML, combined with feature engineering, allows a reliable prediction of essential genes from extensive, publicly available 'omic data sets, with major potential to prioritise such genes (with statistical confidence) for subsequent functional genomic validation. These findings could 'open the door' to fundamental and applied research areas. Evidence of some commonality in the essential gene-complement between these two organisms indicates that an ML-engineering approach could find broader applicability to ecdysozoans such as parasitic nematodes or arthropods, provided that suitably large and informative data sets become/are available for proper feature engineering, and for the robust training and validation of algorithms. This area warrants detailed exploration to, for example, facilitate the identification and characterisation of essential molecules as novel targets for drugs and vaccines against parasitic diseases. This focus is particularly important, given the substantial impact that such diseases have worldwide, and the current challenges associated with their prevention and control and with drug resistance in parasite populations.


Asunto(s)
Caenorhabditis elegans , Genes Esenciales , Animales , Caenorhabditis elegans/genética , Drosophila melanogaster/genética , Eucariontes/genética , Genómica , Aprendizaje Automático
6.
J Clin Oncol ; 40(2): 138-149, 2022 01 10.
Artículo en Inglés | MEDLINE | ID: mdl-34699271

RESUMEN

PURPOSE: Definitive or postoperative chemoradiation (CRT) is curative for human papillomavirus-associated (HPV+) oropharynx cancer (OPC) but induces significant toxicity. As a deintensification strategy, we studied primary transoral surgery (TOS) and reduced postoperative radiation therapy (RT) in intermediate-risk HPV+ OPC. METHODS: E3311 is a phase II randomized trial of reduced- or standard-dose postoperative RT for resected stage III-IVa (American Joint Committee on Cancer-seventh edition) HPV+ OPC, determined by pathologic parameters. Primary goals were feasibility of prospective multi-institutional study of TOS for HPV+ OPC, and oncologic efficacy (2-year progression-free survival) of TOS and adjuvant therapy in intermediate-risk patients after resection. TOS plus 50 Gy was considered promising if the lower limit of the exact 90% binomial confidence intervals exceeded 85%. Quality of life and swallowing were measured by functional assessment of cancer therapy-head and neck and MD Anderson Dysphagia Index. RESULTS: Credentialed surgeons performed TOS for 495 patients. Eligible and treated patients were assigned as follows: arm A (low risk, n = 38) enrolled 11%, intermediate risk arms B (50 Gy, n = 100) or C (60 Gy, n = 108) randomly allocated 58%, and arm D (high risk, n = 113) enrolled 31%. With a median 35.2-month follow-up for 359 evaluable (eligible and treated) patients, 2-year progression-free survival Kaplan-Meier estimate is 96.9% (90% CI, 91.9 to 100) for arm A (observation), 94.9% (90% CI, 91.3 to 98.6]) for arm B (50 Gy), 96.0% (90% CI, 92.8 to 99.3) for arm C (60 Gy), and 90.7% (90% CI, 86.2 to 95.4) for arm D (66 Gy plus weekly cisplatin). Treatment arm distribution and oncologic outcome for ineligible or step 2 untreated patients (n = 136) mirrored the 359 evaluable patients. Exploratory comparison of functional assessment of cancer therapy-head and neck total scores between arms B and C is presented. CONCLUSION: Primary TOS and reduced postoperative RT result in outstanding oncologic outcome and favorable functional outcomes in intermediate-risk HPV+ OPC.


Asunto(s)
Antineoplásicos/uso terapéutico , Biomarcadores de Tumor/análisis , Cisplatino/uso terapéutico , Inhibidor p16 de la Quinasa Dependiente de Ciclina/análisis , Neoplasias Orofaríngeas/terapia , Papillomaviridae/aislamiento & purificación , Faringectomía , Radioterapia de Intensidad Modulada , Carcinoma de Células Escamosas de Cabeza y Cuello/terapia , Adulto , Anciano , Anciano de 80 o más Años , Antineoplásicos/efectos adversos , Quimioradioterapia Adyuvante , Cisplatino/efectos adversos , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Orofaríngeas/química , Neoplasias Orofaríngeas/patología , Neoplasias Orofaríngeas/virología , Faringectomía/efectos adversos , Supervivencia sin Progresión , Estudios Prospectivos , Radioterapia de Intensidad Modulada/efectos adversos , Carcinoma de Células Escamosas de Cabeza y Cuello/química , Carcinoma de Células Escamosas de Cabeza y Cuello/patología , Carcinoma de Células Escamosas de Cabeza y Cuello/virología , Factores de Tiempo
7.
Nat Ecol Evol ; 5(6): 836-844, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33833421

RESUMEN

The Convention on Biological Diversity's post-2020 Global Biodiversity Framework will probably include a goal to stabilize and restore the status of species. Its delivery would be facilitated by making the actions required to halt and reverse species loss spatially explicit. Here, we develop a species threat abatement and restoration (STAR) metric that is scalable across species, threats and geographies. STAR quantifies the contributions that abating threats and restoring habitats in specific places offer towards reducing extinction risk. While every nation can contribute towards halting biodiversity loss, Indonesia, Colombia, Mexico, Madagascar and Brazil combined have stewardship over 31% of total STAR values for terrestrial amphibians, birds and mammals. Among actions, sustainable crop production and forestry dominate, contributing 41% of total STAR values for these taxonomic groups. Key Biodiversity Areas cover 9% of the terrestrial surface but capture 47% of STAR values. STAR could support governmental and non-state actors in quantifying their contributions to meeting science-based species targets within the framework.


Asunto(s)
Conservación de los Recursos Naturales , Animales , Brasil , Colombia , Indonesia , Madagascar , México
8.
J Pediatr ; 232: 294-298, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33493492

RESUMEN

Pseudohyperkalemia and pseudohyponatremia are phenomena in which hematologic disorders with high cell counts result in factitious electrolyte measurements that can result in inappropriate treatment. We describe 2 children with leukemia presenting with both disturbances to highlight the importance of correlating electrolyte results from plasma with those from whole blood before intervening.


Asunto(s)
Hiperpotasemia/etiología , Hiponatremia/etiología , Leucemia-Linfoma Linfoblástico de Células T Precursoras/diagnóstico , Niño , Humanos , Hiperpotasemia/diagnóstico , Hiponatremia/diagnóstico , Lactante , Masculino , Leucemia-Linfoma Linfoblástico de Células T Precursoras/complicaciones
9.
Vet Parasitol ; 289: 109339, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33359968

RESUMEN

Our current understanding of differences in the epidemiology of gastrointestinal nematode (GIN) species in co-grazed sheep and goats is inadequate with reference to the development of sustainable control strategies. The next-generation metabarcoding sequencing method referred to as the 'nemabiome' allows some of these differences to be explored to describe the intensity of co-infecting GIN species. We applied this platform to study sheep and goats that were co-grazed on Guinea grass pasture in northeastern Brazil. Co-grazed goats and sheep were treated with a monepantel anthelmintic, then exposed to the same gastrointestinal nematode species. Overall, there were differences in the prevalence of GIN species identified in the sheep and goats; Trichostrongylus colubriformis and Teladorsagia circumcincta predominated in goat kids, while Haemonchus contortus predominated in adult does, ewes and lambs once burdens became re-established after anthelmintic treatment. Description of the pattern of re-infection following anthelmintic treatment was prevented by the unpredicted poor efficacy of 2.5 mg/kg and 5 mg/kg, respectively, of monepantel against O. columbianum and T. circumcincta in lambs, and T. circumcincta adult does. Differences in drug efficacy between host age and species groups may be important when considering sustainable GIN control strategies for co-grazed animals. The aggregated FECs of the adult does and goat kids representing re-established GIN burdens, were higher than those of the co-grazed adult ewes and lambs. This implies that there are inherent differences in GIN species adaptation to the two naïve small ruminant host species, and shows the need for better understanding of the factors giving rise to this situation associated with exposure to infective larvae and host responses. At the start of the study, the adult does were co-infected with several GIN species, with the highest intensity of T. circumcincta, contrasting with the situation in the adult ewes, in which H. contortus predominated. However, once burdens became re-established after treatment, H. contortus predominated in both adult does and ewes. This demonstrates the potential for host burdens of H. contortus to establish and predominate after anthelmintic treatment when burdens of co-infecting GIN species are low.


Asunto(s)
Código de Barras del ADN Taxonómico , Enfermedades de las Cabras/parasitología , Nematodos/genética , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/parasitología , Aminoacetonitrilo/análogos & derivados , Aminoacetonitrilo/uso terapéutico , Animales , Antihelmínticos/uso terapéutico , Heces/parasitología , Femenino , Genómica , Cabras , Masculino , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/parasitología , Recuento de Huevos de Parásitos , Reacción en Cadena de la Polimerasa , Ovinos
10.
Insects ; 11(12)2020 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-33302371

RESUMEN

In this study we test whether Argentine ants (Linepithema humile) progressively reduce their response to a salient stimulus (alarm pheromone) with increased exposure over time. First, we used a two-chamber olfactometer to demonstrate three focal behaviors of Argentine ants that indicate an alarmed state in response to conspecific alarm pheromone and pure synthetic iridomyrmecin (a dominant component of L. humile alarm pheromone). We then measured how these behaviors changed after repeated exposure to conspecific alarm pheromone from live ants. In addition, we investigate whether there is a difference in the ants' behavioral response after "short" (3 min) versus "long" (6 min) intervals between treatments. Our results show that Argentine ants do exhibit reduced responses to their own alarm pheromone, temporarily ceasing their response to it after four or five exposures, and this pattern holds whether exposure is repeated after "short" or "long" intervals. We suggest alarm pheromones may be perceived as false alarms unless threatening stimuli warrant a continued state of alarm. These results should be kept in mind while developing pheromone-based integrated pest management strategies.

11.
PLoS One ; 15(7): e0236086, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32678835

RESUMEN

South American fire ant decapitating flies in the genus Pseudacteon (Diptera: Phoridae) are potential biocontrol agents of the invasive fire ants Solenopsis invicta and S. richteri in the United States and other regions of the world due to their high host specificity and the direct and indirect damage to their host ants. Despite their importance and the fact that several flies have already been released in the US, little is known about the genetic variability and phylogenetic relationships of Pseudacteon flies parasitizing South American fire ants in the Solenopsis saevissima species-group. A species delimitation analysis was conducted using a distance-based method (ABGD) and two tree-based methods (GMYC and mPTP) using COI sequences of 103 specimens belonging to 20 of the 22 Pseudacteon species known from southern South America. Additionally, phylogenetic relationships between the already described and new candidate species were inferred using mitochondrial (COI) and nuclear (wingless) sequences. The species delimitation analysis suggests that species richness in these flies has been previously underestimated, due to the existence of putative cryptic species within nominal Pseudacteon obtusus, P. pradei, P. tricuspis, P. cultellatus, and P. nudicornis. Geographic distribution and host fire ant species seem to support cryptic lineages, though additional morphological data are needed to corroborate these results. All phylogenetic analyses reveal that South American fire ant decapitating flies are grouped into two main clades, with Pseudacteon convexicauda sister and well differentiated relative to these clades. Neither host nor geographic association appeared to be related to the differentiation of these two main clades within South American fire ant decapitating flies. This work provides information that will allow testing whether the putative cryptic phorid fly species show differences in their effectiveness as biocontrol agents against the highly invasive imported fire ants.


Asunto(s)
Dípteros/clasificación , Dípteros/genética , Especificidad del Huésped , Filogenia , Animales , Análisis de Secuencia de ADN , América del Sur , Especificidad de la Especie
12.
Proc Natl Acad Sci U S A ; 116(46): 23202-23208, 2019 11 12.
Artículo en Inglés | MEDLINE | ID: mdl-31659031

RESUMEN

Consumption of globally traded agricultural commodities like soy and palm oil is one of the primary causes of deforestation and biodiversity loss in some of the world's most species-rich ecosystems. However, the complexity of global supply chains has confounded efforts to reduce impacts. Companies and governments with sustainability commitments struggle to understand their own sourcing patterns, while the activities of more unscrupulous actors are conveniently masked by the opacity of global trade. We combine state-of-the-art material flow, economic trade, and biodiversity impact models to produce an innovative approach for understanding the impacts of trade on biodiversity loss and the roles of remote markets and actors. We do this for the production of soy in the Brazilian Cerrado, home to more than 5% of the world´s species. Distinct sourcing patterns of consumer countries and trading companies result in substantially different impacts on endemic species. Connections between individual buyers and specific hot spots explain the disproportionate impacts of some actors on endemic species and individual threatened species, such as the particular impact of European Union consumers on the recent habitat losses for the iconic giant anteater (Myrmecophaga tridactyla). In making these linkages explicit, our approach enables commodity buyers and investors to target their efforts much more closely to improve the sustainability of their supply chains in their sourcing regions while also transforming our ability to monitor the impact of such commitments over time.


Asunto(s)
Agricultura , Biodiversidad , Comercio , Glycine max , Modelos Teóricos , Animales , Brasil , Internacionalidad
13.
Sci Rep ; 9(1): 1059, 2019 01 31.
Artículo en Inglés | MEDLINE | ID: mdl-30705309

RESUMEN

Cutaneous leishmaniasis is a neglected tropical disease characterized by disfiguring skin lesions. Current chemotherapeutic options depend on toxic, expensive drugs that are both difficult to administer and becoming less effective due to increasing levels of resistance. In comparison, thermotherapy displays greater patient compliance and less adverse systemic effects, but there are still significant issues associated with this. The procedure is painful, requiring local anaesthetic, and is less effective against large lesions. Using nanoparticles to controllably generate heat in a localized manner may provide an alternative solution. Here we evaluate magnetic hyperthermia, using iron oxide magnetic nanoparticles, as a localized, heat-based method to kill the human-infective parasite in vitro. We assessed the effectiveness of this method against the differentiated, amastigote form of the parasite using three distinct viability assays: PrestoBlue, Live/Dead stain and a novel luciferase-based assay. Changes in amastigote morphology and ultrastructure were assessed by immunofluorescence, scanning and transmission electron microscopy. Our findings show that magnetic hyperthermia is an effective method to kill host-infective amastigotes, with morphological changes consistent with heat treatment. This method has the potential to be a step-change for research into new therapeutic options that moves away from the expensive chemotherapeutics currently dominating the research climate.


Asunto(s)
Hipertermia Inducida/métodos , Leishmania mexicana/patogenicidad , Nanopartículas de Magnetita/química , Nanopartículas/química , Supervivencia Celular/fisiología , Citometría de Flujo , Humanos , Microscopía Electrónica de Transmisión , Microscopía Fluorescente
14.
Hepatology ; 69(5): 1916-1930, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-30324707

RESUMEN

Risk of alcoholic cirrhosis is determined by genetic and environmental factors. We aimed to investigate if climate has a causal effect on alcohol consumption and its weight on alcoholic cirrhosis. We collected extensive data from 193 sovereign countries as well as 50 states and 3,144 counties in the United States. Data sources included World Health Organization, World Meteorological Organization, and the Institute on Health Metrics and Evaluation. Climate parameters comprised Koppen-Geiger classification, average annual sunshine hours, and average annual temperature. Alcohol consumption data, pattern of drinking, health indicators, and alcohol-attributable fraction (AAF) of cirrhosis were obtained. The global cohort revealed an inverse correlation between mean average temperature and average annual sunshine hours with liters of annual alcohol consumption per capita (Spearman's rho -0.5 and -0.57, respectively). Moreover, the percentage of heavy episodic drinking and total drinkers among population inversely correlated with temperature -0.45 and -0.49 (P < 0.001) and sunshine hours -0.39 and -0.57 (P < 0.001). Importantly, AAF was inversely correlated with temperature -0.45 (P < 0.001) and sunshine hours -0.6 (P < 0.001). At a global level, all included parameters in the univariable and multivariable analysis showed an association with liters of alcohol consumption and drinkers among population once adjusted by potential confounders. In the multivariate analysis, liters of alcohol consumption associated with AAF. In the United States, colder climates showed a positive correlation with the age-standardized prevalence of heavy and binge drinkers. Conclusion: These results suggest that colder climates may play a causal role on AAF mediated by alcohol consumption.


Asunto(s)
Consumo de Bebidas Alcohólicas/efectos adversos , Clima Frío/efectos adversos , Cirrosis Hepática Alcohólica/epidemiología , Consumo de Bebidas Alcohólicas/epidemiología , Estudios Transversales , Humanos , Internacionalidad , Cirrosis Hepática Alcohólica/etiología , Luz Solar , Estados Unidos/epidemiología
15.
J Chem Ecol ; 44(12): 1101-1114, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30430363

RESUMEN

Cuticular hydrocarbons (CHCs), the dominant fraction of the insects' epicuticle and the primary barrier to desiccation, form the basis for a wide range of chemical signaling systems. In eusocial insects, CHCs are key mediators of nestmate recognition, and colony identity appears to be maintained through a uniform CHC profile. In the unicolonial Argentine ant Linepithema humile, an unparalleled invasive expansion has led to vast supercolonies whose nestmates can still recognize each other across thousands of miles. CHC profiles are expected to display considerable variation as they adapt to fundamentally differing environmental conditions across the Argentine ant's expanded range, yet this variation would largely conflict with the vastly extended nestmate recognition based on CHC uniformity. To shed light on these seemingly contradictory selective pressures, we attempt to decipher which CHC classes enable adaptation to such a wide array of environmental conditions and contrast them with the overall CHC profile uniformity postulated to maintain nestmate recognition. n-Alkanes and n-alkenes showed the largest adaptability to environmental conditions most closely associated with desiccation, pointing at their function for water-proofing. Trimethyl alkanes, on the other hand, were reduced in environments associated with higher desiccation stress. However, CHC patterns correlated with environmental conditions were largely overriden when taking overall CHC variation across the expanded range of L. humile into account, resulting in conserved colony-specific CHC signatures. This delivers intriguing insights into the hierarchy of CHC functionality integrating both adaptation to a wide array of different climatic conditions and the maintenance of a universally accepted chemical profile.


Asunto(s)
Adaptación Fisiológica , Hormigas/fisiología , Hidrocarburos/metabolismo , Alcanos/análisis , Alcanos/aislamiento & purificación , Alcanos/metabolismo , Animales , Argentina , Biodiversidad , California , Clima , Cromatografía de Gases y Espectrometría de Masas , Hidrocarburos/análisis , Hidrocarburos/aislamiento & purificación , Especies Introducidas , Extracción Líquido-Líquido
16.
J Anim Ecol ; 87(6): 1653-1666, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30047994

RESUMEN

Once established in new areas, introduced species may exhibit changes in their biology due to phenotypic plasticity, novel selection pressures and genetic drift. Moreover, the introduction process itself has been hypothesised to act as a selective filter for traits that promote invasiveness. We tested the hypothesis that behaviours thought to promote invasiveness-such as increased foraging activity and aggression-are selected for during invasion by comparing traits among native and introduced populations of the widespread Argentine ant (Linepithema humile). We studied Argentine ant populations in the native range in Argentina and in three invaded regions along an introduction pathway: California, Australia and New Zealand. In each region, we set up 32 experimental colonies to measure foraging activity and interspecific aggression in a subset of the study regions. These colonies were subject to experimental manipulation of carbohydrate availability and octopamine, a biogenic amine known to modulate behaviour in insects, to measure variation in behavioural plasticity. We found variation in foraging activity among populations, but this variation was not consistent with selection on behaviour in relation to the invasion process. We found that colonies with limited access to carbohydrates exhibited unchanged exploratory behaviour, but higher exploitation activity and lower aggression. Colonies given octopamine consistently increased foraging behaviour (both exploration and exploitation), as well as aggression when also sugar-deprived. There was no difference in the degree of behavioural response to our experimental treatments along the introduction pathway. We did not find support for selection of behavioural traits associated with invasiveness along the Argentine ant's introduction pathway or clear evidence for an association between the introduction process and variation in behavioural plasticity. These results indicate that mechanisms promote behavioural variation in a similar fashion both in native and introduced ranges. Our results challenge the assumption that introduced populations always perform better in key behavioural traits hypothesised to be associated with invasion success.


Asunto(s)
Hormigas , Animales , Argentina , Australia , California , Nueva Zelanda
17.
J Med Entomol ; 54(6): 1643-1648, 2017 11 07.
Artículo en Inglés | MEDLINE | ID: mdl-28981681

RESUMEN

Puerto Rico (PR) has a long history of vector-borne disease and insecticide-resistant Aedes aegypti (L.). Defining contributing mechanisms behind phenotypic resistance is critical for effective vector control intervention. However, previous studies from PR have each focused on only one mechanism of pyrethroid resistance. This study examines the contribution of P450-mediated enzymatic detoxification and sodium channel target site changes to the overall resistance phenotype of Ae. aegypti collected from San Juan, PR, in 2012. Screening of a panel of toxicants found broad resistance relative to the lab susceptible Orlando (ORL1952) strain. We identified significant resistance to representative Type I, Type II, and nonester pyrethroids, a sodium channel blocker, and a sodium channel blocking inhibitor, all of which interact with the sodium channel. Testing of fipronil, a chloride channel agonist, also showed low but significant levels of resistance. In contrast, the PR and ORL1952 strains were equally susceptible to chlorfenapyr, which has been suggested as an alternative public health insecticide. Molecular characterization of the strain indicated that two common sodium channel mutations were fixed in the population. Topical bioassay with piperonyl butoxide (PBO) indicated cytochrome P450-mediated detoxification accounts for approximately half of the resistance profile. Transcript expression screening of cytochrome P450s and glutathione-S-transferases identified the presence of overexpressed transcripts. This study of Puerto Rican Ae. aegypti with significant contributions from both genetic changes and enzymatic detoxification highlights the necessity of monitoring for resistance but also defining the multiple resistance mechanisms to inform effective mosquito control.


Asunto(s)
Aedes/genética , Sistema Enzimático del Citocromo P-450/genética , Glutatión Transferasa/genética , Resistencia a los Insecticidas/genética , Insecticidas , Aedes/enzimología , Animales , Femenino , Puerto Rico , Canales de Sodio Activados por Voltaje/genética
20.
Am J Transplant ; 16(10): 2816-2835, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27273869

RESUMEN

The Banff Working Group on Liver Allograft Pathology reviewed and discussed literature evidence regarding antibody-mediated liver allograft rejection at the 11th (Paris, France, June 5-10, 2011), 12th (Comandatuba, Brazil, August 19-23, 2013), and 13th (Vancouver, British Columbia, Canada, October 5-10, 2015) meetings of the Banff Conference on Allograft Pathology. Discussion continued online. The primary goal was to introduce guidelines and consensus criteria for the diagnosis of liver allograft antibody-mediated rejection and provide a comprehensive update of all Banff Schema recommendations. Included are new recommendations for complement component 4d tissue staining and interpretation, staging liver allograft fibrosis, and findings related to immunosuppression minimization. In an effort to create a single reference document, previous unchanged criteria are also included.


Asunto(s)
Rechazo de Injerto/etiología , Rechazo de Injerto/patología , Isoanticuerpos/inmunología , Trasplante de Hígado/efectos adversos , Aloinjertos , Humanos , Informe de Investigación
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