Genetic diversity and insecticide resistance during the growing season in the green peach aphid (Hemiptera: Aphididae) on primary and secondary hosts: a farm-scale study in Central Chile.

The seasonal dynamics of neutral genetic diversity and the insecticide resistance mechanisms of insect pests at the farm scale are still poorly documented. Here this was addressed in the green peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) in Central Chile. Samples were collected from an insecticide sprayed peach (Prunus persica L.) orchard (primary host), and a sweet-pepper (Capsicum annum var. grossum L.) field (secondary host). In addition, aphids from weeds (secondary hosts) growing among these crops were also sampled. Many unique multilocus genotypes were found on peach trees, while secondary hosts were colonized mostly by the six most common genotypes, which were predominantly sensitive to insecticides. In both fields, a small but significant genetic differentiation was found between aphids on the crops vs. their weeds. Within-season comparisons showed genetic differentiation between early and late season samples from peach, as well as for weeds in the peach orchard. The knock-down resistance (kdr) mutation was detected mostly in the heterozygote state, often associated with modified acetylcholinesterase throughout the season for both crops. This mutation was found in high frequency, mainly in the peach orchard. The super-kdr mutation was found in very low frequencies in both crops. This study provides farm-scale evidence that the aphid M. persicae can be composed of slightly different genetic groups between contiguous populations of primary and secondary hosts exhibiting different dynamics of insecticide resistance through the growing season.

The invasion route for an insect pest species: the tobacco aphid in the New World.

Biological invasions are rapid evolutionary events in which populations are usually subject to a founder event during introduction followed by rapid adaptation to the new environment. Molecular tools and Bayesian approaches have shown their utility in exploring different evolutionary scenarios regarding the invasion routes of introduced species. We examined the situation for the tobacco aphid, Myzus persicae nicotianae, a recently introduced aphid species in Chile. Using seven microsatellite loci and approximate Bayesian computation, we studied populations of the tobacco aphid sampled from several American and European countries, identifying the most likely source populations and tracking the route of introduction to Chile. Our population genetic data are consistent with available historical information, pointing to an introduction route of the tobacco aphid from Europe and/or from other putative populations (e.g. Asia) with subsequent introduction through North America to South America. Evidence of multiple introductions to North America from different genetic pools, with successive loss of genetic diversity from Europe towards North America and a strong bottleneck during the southward introduction to South America, was also found. Additionally, we examined the special case of a widespread multilocus genotype that was found in all American countries examined. This case provides further evidence for the existence of highly successful genotypes or 'superclones' in asexually reproducing organisms.

Edad al momento del trasplante: ¿Quiénes tienen riesgo de mala evolución ? / Age at transplantation: who are at risk of a poor outcome ?

Introducción: Si bien la sobrevida de paciente e injerto en niños con trasplante renal (TxR) ha mejorado, algunos sugieren que la edad al TxR es predictora de malos resultados, y los mayores tendrían peor evolución. Objetivo: Definir sobrevida de paciente e injerto según edad al TxR, y factores pronósticos de fracaso en aquellos con peor evolución. Material y métodos: Cohorte retrospectivo de todos los pacientes con TxR en el Hospital Garrahan desde el 01-01-2002 hasta el 01-03-2016. Resultados: de 431 pacientes, 44, (10%) tenían < 6a, 179 (42%)> 6 y <12 y 208 (48%) ≥12 años. La sobrevida del paciente a 8 años fue 97%, 99% y 95% (p=0,2), y la del injerto de: 86%, 69% y 30% respectivamente (p=<0,001). En los ≥ de 12 años, con peor evolución, se incluyeron al análisis univariado como factores de riesgo de pérdida de injerto: GSFS como causa de IRC : HR: 9,4; (p<0,001), Rechazo Agudo (RA) temprano: HR: 8,1; (p<0,001), RA tardío: HR: 4,3; (p<0.001), DGF: HR: 4,1; (p<0,001), No adherencia: HR: 2,3; (p=0,02), Edad de DC > 35a: HR: 1,95 (p=0,1), Tiempo en diálisis: HR: 1,1 (p=0,1), Número de incompatibilidades HLAB y HLADR: HR: 0,8 (p=0,3), Tiempo de Isquemia : 0,9 (p=0,5), Sexo del receptor: HR:0,8 (p=0,6), Donante Cadavérico: HR: 1,2; (p=0,6), 2do TxR : HR: 1,2; (p=0,7). En análisis multivariado: RA tardío: HR: 12,9 (p<0,001), GSFS como causa de IRC: HR: 12,5 (p<0,001), RA temprano: HR: 9 (p<0,001), y DGF: HR: 4,9 (p<0,001). Conclusión: la sobrevida del injerto en adolescentes es inferior. Merecen atención, la prevención de la no adherencia asociada a rechazo, el paciente con GSFS y el retardo de la función pos TxR (AU)

Introduction: Although patient and graft survival of children with a kidney transplantation (KTx) has improved, it has been suggested that older age at KTx is a predictive factor of poor outcome. Aim: To evaluate patient and graft survival according to age at KTx and define predictive factors in those with a poor outcome. Material and methods: A retrospective cohort study was conducted in all patients who underwent KTx at Garrahan Hopital between 01-01-2002 and 01-03-2016. Results: Of 431 patients, 44 (10%) were <6yr, 179 (42%) >6yr, and <12yr, and 208 (48%) ≥12yr. Eight-year patient survival was 97%, 99%, and 95% (p=0.2) and graft survival was 86%, 69%, and 30% (p=<0.001), respectively. In children ≥12 yr, with a worse outcome, the following risk factors of graft loss were included in univariate analysis: FSGS-related CFR: HR: 9.4; (p<0.001), early acute rejection (AR): HR: 8.1; (p<0.001), late AR: HR: 4.3; (p<0.001), DGF: HR: 4.1; (p<0.001), non-adherence: HR: 2.3; (p=0.02), age of deceased donor >35yr: HR: 1.95 (p=0.1), time on dialysis: HR: 1.1 (p=0.1), number of HLA-B and HLA-DR mismatches: HR: 0.8 (p=0.3), cold ischemia time: 0.9 (p=0.5), recipient sex: HR:0.8 (p=0.6), deceased donor: HR: 1.2; (p=0.6), second KTx: HR: 1.2; (p=0.7; and in multivariate analysis: late AR: HR: 12.9 (p<0.001), FSGS-related CFR: HR: 12.5 (p<0.001), early AR: HR: 9 (p<0.001), and DGF: HR: 4.9 (p<0.001). Conclusion: Graft survival is lower in adolescents. Prevention of rejection associated with non-adherence, FSGS, and post-KTx DGF should be taken into account (AU)

Genetic structure and clonal diversity of an introduced pest in Chile, the cereal aphid Sitobion avenae.

In Chile, the aphid Sitobion avenae is of recent introduction, lives on cultivated and wild Poaceae, and is thought to reproduce by permanent parthenogenesis. In order to study the genetic variability and population structure of this species, five microsatellite loci were typed from individual aphids collected from different cultivated and wild host plants, from different geographical zones, and years. Chilean populations showed a high degree of heterozygosity and a low genetic variability across regions and years, with four predominant genotypes representing nearly 90% of the sample. This pattern of low clonal diversity and high heterozygosity was interpreted as the result of recent founder events from a few asexually reproducing genotypes. Most geographical and temporal variation observed in the genetic composition resulted from fluctuations of a few predominant clones. In addition, comparisons of the genotypes found in Chile with those described in earlier surveys of S. avenae populations in Western Europe led us to identify 'superclones' with large geographical distribution and high ecological success, and to make a preliminary exploration of the putative origin(s) of S. avenae individuals introduced to Chile.

Genetic diversity and insecticide resistance of Myzus persicae (Hemiptera: Aphididae) populations from tobacco in Chile: evidence for the existence of a single predominant clone.

The tobacco-feeding race of Myzus persicae (Sulzer), formerly known as M. nicotianae Blackman, was introduced into Chile during the last decade. In order to evaluate the genetic diversity and insecticide resistance status of Chilean tobacco aphid populations, a field survey was conducted in 35 tobacco fields covering a 300 km latitudinal survey. The populations sampled were characterized using microsatellite markers and morphometric multivariate analysis. Insecticide resistance levels were assessed through a microplate esterase assay and the mutation status of the kdr gene. All samples collected corresponded to the same anholocyclic aphid genotype, and showed morphological variation within the range expected for the tobacco-feeding race of M. persicae. Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides.

Hemodialisis en niños con peso menor a 15Kg / Hemodialysis in children weighing less then 15 Kg

La HD en niños de bajo peso es técnicamente dificultosa y es necesario trabajar en forma multidisciplinaria Hay poca biografía sobre la evolución de estos pacientes. Nosotros analizamos retrospectivamente a 31 niños con peso menor de 15 Kg. que fueron tratados con HD en forma transitoria o definitiva entre 1991-2003. Registramos 47 períodos dialíticos pues 8 pacientes tuvieron más de un ingreso. Cinco niños presentaron insuficiencia renal aguda (IRA) recuperando la función renal aguda (FR) entre 1-12 días. Los demás presentaron insuficiencia renal crónica terminal (IRCT). Dieciocho pacientes requirieron HD por complicaciones de la diálisis peritoneal continua ambulatoria (DPCA). La HD fue el tratamiento de elección en ocho. Todos fueron dializados a través de una línea central (catéteres transitorios). Se colocaron 4 catéteres permanentes y 17 prótesis arteriovenosas y 3 fístulas arteriovenosas (FAV). El 57 por ciento de los catéteres presentaron complicaciones: 18 por ciento infección, 18 por ciento disfunsión 14 por ciento salida accidental y 7 por ciento trombosis. La anemia fue un problema frecuente a pesar del uso de eritropoyetina (EPO). En la evolución 5 recuperaron FR. Once pacientes se traplantaron exitosamente, 6 volvieron a DPCA, 3 volvieron a su provincia de origen, 2 pacientes continúan en HD y 4 fallecieron. La HD en niños pequeños es factible pero la morvi-mortalidad es alta y está limitada a períodos cortos por sus frecuentes complicaciones.