ABSTRACT
It is well understood that the out-of-Africa habitat expansion of D. melanogaster was associated with the fixation of many beneficial mutations. Nevertheless, it is not clear yet whether these beneficial mutations segregated already in Africa or originated outside of Africa. In this article, we describe an ongoing selective sweep specific to one European population. One microsatellite allele has increased in a population from The Netherlands to a frequency of 18%, whereas it is virtually absent in 12 other European populations. The selective sweep resulted in a genomic region of more than 600 kb that is identical by descent. This is probably the first evidence of a beneficial mutation that has arisen outside of Africa and has resulted in a selective sweep localized in a population from The Netherlands.
Subject(s)
Drosophila melanogaster/genetics , Mutation/genetics , X Chromosome/genetics , Adaptation, Biological/genetics , Alleles , Animals , Gene Frequency , Genetic Variation , Genetics, Population , Microsatellite Repeats/genetics , NetherlandsABSTRACT
Previous work showed that insecticide resistance in Drosophila melanogaster is correlated with the insertion of an Accord-like element into the 5' region of the cytochrome P450 gene, Cyp6g1. Here, we study the distribution of the Accord-like element in 673 recently collected D. melanogaster lines from 34 world-wide populations. We also examine the extent of microsatellite variability along a 180-kilobase (kb) genomic region of chromosome II encompassing the resistance gene. We confirm a 100% correlation of the Accord insertion with insecticide resistance and a significant reduction in variability extending at least 20 kb downstream of the Cyp6g1 gene. The frequency of the Accord insertion differs significantly between East African (32-55%) and nonAfrican (85-100%) populations. This pattern is consistent with a selective sweep driving the Accord insertion close to fixation in nonAfrican populations as a result of the insecticide resistance phenotype it confers. This study confirms that hitchhiking mapping can be used to identify beneficial mutations in natural populations.
Subject(s)
Cytochrome P-450 Enzyme System/genetics , DDT/poisoning , DNA Transposable Elements/genetics , Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Drug Resistance/genetics , Selection, Genetic , Analysis of Variance , Animals , DNA Primers , Drosophila melanogaster/drug effects , Electrophoresis, Agar Gel , Gene Frequency , Genetic Carrier Screening , Genetic Variation , Microsatellite Repeats/genetics , Mutation/genetics , Polymerase Chain ReactionABSTRACT
OBJECTIVE: To determine the clinical significance in normal Pap smears of HPV detection as determined by Hybrid Capture (HC) and in situ hybridization analyses. STUDY DESIGN: We studied 135 consecutive Pap smears as well as 46 other smears from high-risk patients each initially diagnosed as within normal limits. RESULTS: The 135 "normal" Pap smears were rescreened, and 6 (4%) where found to be either ASCUS or SIL. In the remaining 129 cases, HPV DNA was detected in 0% and 9%, respectively, using in situ hybridization and HC I. Upon rescreening the high-risk patients, nine (20%) were reclassified as having SIL/ASCUS; each was in situ hybridization positive, and eight were HC positive; six (67%) of these women developed SIL on follow-up. In the 37 Pap smears in high-risk women still within normal limits after manual rescreening, HPV was detected in 2% by in situ hybridization and 46% by HC; 6% of the HC-positive women developed SIL on follow-up. CONCLUSION: In situ hybridization rarely detects HPV in Pap smears diagnosed as within normal limits after manual rescreening. In situ hybridization is very effective in detecting rare, atypical cells in Pap smears diagnosed as within normal limits and, in a high-risk population, is predictive of SIL on clinical follow-up.
Subject(s)
DNA, Viral/analysis , Papanicolaou Test , Papillomaviridae/isolation & purification , Papillomavirus Infections/diagnosis , Tumor Virus Infections/diagnosis , Vaginal Smears , Adolescent , Adult , Aged , Female , Humans , In Situ Hybridization/methods , Middle Aged , Papillomaviridae/genetics , Quality Control , Reference Values , Reproducibility of Results , Sensitivity and Specificity , Uterine Cervical Dysplasia/diagnosis , Uterine Cervical Dysplasia/virology , Uterine Cervical Neoplasms/diagnosis , Uterine Cervical Neoplasms/virologyABSTRACT
The purpose of this study is to report an unusual variant of cervical squamous cell carcinoma, not associated with either human papillomavirus infection or antecedent squamous intraepithelial lesions. Five women had a diagnosis of invasive cervical cancer discovered at hysterectomy performed for prolapse (two cases), leiomyoma (one case), or a vaginal fistula (two cases). The women ranged in age from 47 to 78 years (mean 59 years). Four of the five had a history of normal Papanicolaou (Pap) smears; the other had a Pap smear diagnosis of atypical squamous cells of undetermined significance (ASCUS). All had large cervical tumors (two with parametrial involvement and one with vaginal involvement) that showed extensive keratin formation, an inverted pattern of growth, and, except for one case, minimal cytologic atypia. There was extensive hyperkeratosis and parakeratosis adjacent to each tumor; none had evidence of squamous intraepithelial lesion. Human papillomavirus testing by polymerase chain reaction in situ hybridization and reverse-transcribed polymerase chain reaction in situ was negative in each case, compared with a detection rate of 107 of 108 (99%) for squamous intraepithelial lesion-associated cervical squamous cell and adenocarcinomas. Two of the women died of extensive local recurrence; two other women were recently diagnosed. We conclude that highly differentiated keratinizing squamous cell carcinoma of the cervix is a rare entity not associated with human papillomavirus infection or squamous intraepithelial lesion and thus difficult to detect on routine cervical cancer screening.
