QTL mapping of genome regions controlling temephos resistance in larvae of the mosquito aedes aegypti

Introduction: The mosquito Aedes aegypti is the principal vector of dengue and yellow fever flaviviruses. Temephos is an organophosphate insecticide used globally to suppress Ae. aegypti larval populations but resistance has evolved in many locations. Methodology/Principal Findings: Quantitative Trait Loci (QTL) controlling temephos survival in Ae. aegypti larvae were mapped in a pair of F3 advanced intercross lines arising from temephos resistant parents from Solidaridad, México and temephos susceptible parents from Iquitos, Peru. Two sets of 200 F3 larvae were exposed to a discriminating dose of temephos and then dead larvae were collected and preserved for DNA isolation every two hours up to 16 hours. Larvae surviving longer than 16 hours were considered resistant. For QTL mapping, single nucleotide polymorphisms (SNPs) were identified at 23 single copy genes and 26 microsatellite loci of known physical positions in the Ae. aegypti genome. In both reciprocal crosses, Multiple Interval Mapping identified eleven QTL associated with time until death. In the Solidaridad6Iquitos (SLD6Iq) cross twelve were associated with survival but in the reciprocal IqxSLD cross, only six QTL were survival associated. Polymorphisms at acetylcholine esterase (AchE) loci 1 and 2 were not associated with either resistance phenotype suggesting that target site insensitivity is not an organophosphate resistance mechanism in this region of México. Conclusions/Significance: Temephos resistance is under the control of many metabolic genes of small effect and dispersed throughout the Ae. aegypti genome

Temporal distribution and genetic variants in influenza A(H1N1)pdm09 virus circulating in Mexico, seasons 2012 and 2013

The 2012 and 2013 annual influenza epidemics in Mexico were characterized by presenting different seasonal patterns. In 2012 the A(H1N1)pdm09 virus caused a high incidence of influenza infections after a two-year period of low circulation; whereas the 2013 epidemic presented circulation of the A(H1N1)pdm09 virus throughout the year. We have characterized the molecular composition of the Hemagglutinin (HA) and Neuraminidase (NA) genes of the A(H1N1)pdm09 virus from both epidemic seasons, emphasizing the genetic characteristics of viruses isolated from Yucatan in Southern Mexico. The molecular analysis of viruses from the 2012 revealed that all viruses from Mexico were predominantly grouped in clade 7. Strikingly, the molecular characterization of viruses from 2013 revealed that viruses circulating in Yucatan were genetically different to viruses from other regions of Mexico. In fact, we identified the occurrence of two genetic variants containing relevant mutations at both the HA and NA surface antigens. There was a difference on the temporal circulation of each genetic variant, viruses containing the mutations HA-A141T / NA-N341S were detected in May, June and July; whereas viruses containing the mutations HA-S162I / NAL206S circulated in August and September. We discuss the significance of these novel genetic changes

Frequency and Distribution of Pulpal Calcifications in Teeth Involved in Jaw Tumors

Pulp calcifications are idiopathic mineralized masses associated with irritation, age, trauma, and systemic or genetic diseases. The objective of this work was to examine frequency and distribution of pulp calcifications in teeth involved in jaw tumors, analyzing their relationship with age, sex, location, size, and diagnosis of the lesion in a sample of 21 teeth associated with tumors of the jaws. Imaging analysis included CT scans, periapical X-rays, and orthopantomography of the clinical record; histological analysis included pulp tissue fixed in 10% buffered formalin for 24 h, with hematoxylin and eosin staining, and examined under light microscope. A chi-square test was applied to associate calcifications with all variables. The tumor lesions were from patients aged 17–66 years. Calcifications were observed in 38.1% of cases on image and histologically in 76.2%; 56% were nodular and 68.8% were distributed in chamber and root canal. The male sex presented a higher frequency of pulp calcifications, estimating a statistically significant difference with respect to women (p = 0.004); there was no statistical significance with the other variables. In conclusion, the pulp tissue of teeth affected by maxillary tumors presents a percentage of pulp calcifications similar to the tissue where the periradicular tissue is intact

Resistance to permethrin in Aedes aegypti (L.) in Northern México.

Diagnostic dose (DD) of permethrin was determined in Aedes aegypti (L.), from three states (Coahuila, Sonora, and Tamaulipas) in northern Mexico. After exposing 10 groups of 100 females to the DD obtained and producing 50% mortality, individuals were divided into two categories: survivors and dead. Mosquitoes in each of these categories were dissected to separate the head, thorax, and abdomen. Biochemical tests were done on the head and thorax to determine activity by resistance-related enzymes including: α and β-esterases, mixed-function oxidases (MFOs), glutathione-S-transferase (GST) and insensitive acetyl cholinesterase (iAChE). Results were compared with those for a susceptible strain of Ae. aegypti from New Orleans. A population from Coahuila showed iAChE as the only enzyme activity that surpassed the threshold established with the susceptible strain, however, this mechanism is not associated with resistance to pyrethroids, but rather with resistance to organophosphate and carbamate insecticides. For the populations from Tamaulipas, none of the mechanisms studied were important in conferring resistance to permethrin. MFOs were present at elevated levels of activity, appearing as the main detoxifying mechanism, in the population from Sonoita, Sonora state

Proportion surviving among larvae plotted against the three possible genotypes at each of the markers found to be significantly associated with the DOA phenotype (Table 2).

<p>Iq/Iq = both alleles inherited from the Iquitos parent, Iq/SLD = heterozygous for alleles inherited from both Iquitos and Solidaridad parents, SLD/SLD = both alleles inherited from the Solidaridad parent. Error bars are Bayes 95% highest density intervals (HDI), credible differences exist when the 95% HDI fail to overlap. For the SLD×Iq cross, A) shows the relationship among genotypes at four loci on chromosome 1 and proportion surviving, B) is the relationship among genotypes at four loci on chromosome 2 and proportion surviving, and C) indicates the relationship among genotypes at four loci on chromosome 3 and proportion surviving. For the Iq×SLD cross, D) shows the relationship among genotypes at one locus on chromosome 1, two loci on chromosome 2 and 3 loci on chromosome 3 and proportion surviving.</p

Physical positions of markers and QTL affecting hours until death (H) and survival (D).

<p>Physical markers correspond to the system described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003177#pntd.0003177-Timoshevskiy2" target="_blank">[52]</a>.</p

Analysis of Variance (ANOVA) of the hours until death among the three genotype classes.

<p>The means among the three classes are listed as are the probabilities estimated in the ANOVA. Probabilities from the ANOVA are listed in the sixth column. The last column indicates whether the allele inherited from the SLD F_S3 P₁ parent conferred resistance while the allele inherited from the Iq P₁ parent were susceptible.</p><p>Analysis of Variance (ANOVA) of the hours until death among the three genotype classes.</p