Diversidad genética de aedes aegypti en el eje transfronterizo Central-Alto Paraná en Paraguay / Genetic diversity of Aedes aegypti in the central-upper Paraná Cross-Border axis in Paraguay

RESUMEN Objetivos: Conocer la diversidad genética de Aedes aegypti en el corredor vial transfronterizo Central-Alto Paraná de Paraguay, con registros de casos de dengue. Materiales y métodos: Se seleccionaron veinte hembras adultas de la eclosión de huevos de Ae. aegypti procedentes de casas geolocalizadas en los departamentos de Alto Paraná, Caaguazú, Cordillera y Central, entre el 2018 y 2019. Se extrajo ADN del tejido de las hembras para amplificación aleatoria de sus patrones polimórficos mediante amplificación aleatoria del ADN polimórfico por PCR (RAPD-PCR), usando cebadores H3 y B03 a fin de conocer parámetros genéticos de diversidad poblacional. Las relaciones entre las poblaciones de mosquitos según la localidad fueron visualizadas mediante análisis no apareado de la media aritmética. Las áreas idóneas de distribución geográfica real y potencial de estas poblaciones de Ae. aegypti fueron analizadas mediante DIVA-GIS 7.3.0 y MAXENT. Resultados: Se identificaron 40 loci mediante perfiles RAPD-PCR, con diferenciación génica moderada (Gst = 0,12). El corredor transfronterizo presentó condiciones bioclimáticas para la presencia de poblaciones variantes de Ae. aegypti, siendo determinantes en la distribución la precipitación del trimestre más cálido y la temperatura media del trimestre más seco. Conclusiones: Se evidencia que existe diversidad genética moderada en las poblaciones de Ae. aegypti procedentes de zonas con registros de casos de dengue ubicadas en el corredor vial transfronterizo que une los departamentos Central y Alto Paraná de Paraguay. El estudio de variabilidad genética de Ae. aegypti es de gran utilidad para la vigilancia entomoepidemiológica y evaluación de posibles eventos de resistencia al control químico.

ABSTRACT Objective: To determine the genetic diversity of Aedes aegypti in the Central-Alto Paraná cross-border road corridor of Paraguay, an area that has reports of dengue cases. Materials and methods: Twenty adult females were selected from hatching Ae. aegypti eggs from households geolocated in the departments of Alto Paraná, Caaguazú, Cordillera and Central, between 2018 and 2019. DNA was extracted from the tissue of females for amplifying their polymorphic patterns by random amplification of polymorphic DNA by PCR (RAPD-PCR), using primers H3 and B03 in order to identify genetic parameters of population diversity. The relationships between mosquito populations according to locality were observed by unpaired arithmetic mean analysis. We used DIVA-GIS 7.3.0 and MAXENT to analyze the suitable areas of actual and potential geographic distribution of these Ae. aegypti populations. Results: Forty loci were identified by RAPD-PCR profiling, with moderate gene differentiation (Gst = 0.12). The cross-border corridor presented bioclimatic conditions for the presence of variant populations of Ae. aegypti, with precipitation in the warmest quarter and mean temperature in the driest quarter being determinant in the distribution. Conclusions: There is evidence of moderate genetic diversity in Ae. aegypti populations from areas that have reported dengue cases in the cross-border road corridor linking the Central and Alto Paraná departments of Paraguay. The study of genetic variability of Ae. aegypti is very useful for entomo-epidemiological surveillance and evaluation of possible resistance to chemical control.

Analysis of zoonotic dermatophytoses in 64 family-based groups / 中华皮肤科杂志

Objective To investigate the distribution and epidemiology of fungal pathogens in zoonotic dermatophytoses.Methods Seventy-four patients with dermatophytoses and 72 pets from 64 families,who were all culture positive for dermatophytes,were included in this study and classified into 64 family-based groups.Fungal culture and direct microscopic examination were carried out for species identification of fungal isolates,internal transcribed spacer (ITS) sequence analysis and random amplified polymorphic DNA (RAPD) analysis were performed for molecular identification and homology analysis.Results Dermatophyte species were consistent among the patients and pets from the same families for all the 64 family-based groups.A total of 146 fungal strains were isolated,including 93 Microsporum canis (M.canis) strains and 53 Trichophyton interdigitale (T.interdigitale) strains.M.canis was isolated from 42 (65.7％) family-based groups including 34 groups keeping cats and 8 groups keeping dogs,while T.interdigitale from 22 (34.3％) groups,including 14 groups keeping rabbits,6 groups keeping cats and 2 groups keeping dogs.There were 54 (75.0％) pets with obvious clinical symptoms (erythema,desquamation,depilation,etc),and 18 (25.0％) asymptomatic pets which were all cats.Among the 18 asymptomatic cats,14 carried M.canis,and 4 T.interdigitale.ITS sequencing and RAPD analysis revealed a high homology between the fungal pathogens in the same family-based groups.Conclusions M.canis and T.interdigitale are common species of dermatophytes in zoonotic dermatophytoses,and both of them have host specificity.Zoonotic dermatophytes can be transmitted between human and domestic animals,and attention should be paid to asymptomatic animals (carriers).

Using molecular markers to assess Streptococcus mutans variability and the biological risk for caries

AIM: To characterize the genetic variability of Streptococcus mutans isolates and to correlate this variability with different colonization profiles observed during dental caries in a sample of children. METHODS: S. mutans samples were isolated from the saliva of 30 children with varying histories of dental caries, and they were characterized according to morphological and biochemical markers and the sequences of their 16S-23S intergenic spacer region. The genetic variability of the isolates was first assessed using Random Amplified Polymorphic DNA (RAPD) markers. Next, the isolates were differentiated by sequencing a specific region of the gene encoding the enzyme glucosyltransferase B (gtfB). RESULTS: Characterization using RAPD markers uncovered significant genetic variability among the samples and indicated the existence of clusters, which allowed us to reconstruct both the origin and clinical history of the disease. By sequencing the 16S-23S intergenic region, it was found that all of the isolates belonged to the species S. mutans. Based on the genetic similarity of the isolates and pattern of amino acid variations identified by partial sequencing of the gtfB gene, base-pair changes were identified and correlated with different virulence patterns among the isolates. CONCLUSIONS: The partial sequencing of the gtfB gene can be a useful tool for elucidating the colonization patterns of S. mutans. As amino acid variations are likely to be correlated with differences in biological risk, molecular characterization, such as that described in this paper, could be the key for assessing the development of dental caries in children...

Susceptibilidad antimicrobiana y genotipificación de Pseudomonas aeruginosa de pacientes con fibrosis quística y otras patologías en Cartagena (Colombia) / Antimicrobial susceptibility and genotypification of Pseudomonas aeruginosa from cystic fibrosis patients and other diseases in Cartagena (Colombia)

Objetivo: el objetivo de este estudio fue analizar el genotipo y susceptibilidad antimicrobiana de Pseudomonas aeruginosa de pacientes con fibrosis quística y otras patologías. Materiales y métodos: se analizaron 20 aislados de pacientes con fibrosis quística y 20 de pacientes con otras enfermedades por medio de la prueba de susceptibilidad antimicrobiana por microdilución en caldo y técnica del ADN polimorfo amplificado aleatorio. Resultados: se observó que los aislados de pacientes con fibrosis quística presentaron mayor resistencia (56 %) en comparación con aislados de pacientes sin fibrosis quística (25 %). Los antimicrobianos más efectivos en ambos grupos fueron cefepima, ceftriaxona y meropenem. Desde el punto de vista genotípico, se observa heterogeneidad entre las cepas de pacientes con fibrosis quística y dos grupos con cepas idénticas de origen hospitalario, lo que sugiere una posible transmisión cruzada. Conclusión: Concluimos que los porcentajes de resistencia de Pseudomonas aeruginosa en este estudio son altas, y este hallazgo se acentúa en el caso de pacientes con fibrosis quística, lo cual deja muy pocas opciones de tratamiento. La tipificación por técnica del ADN polimórfico amplificado aleatorio permitió conocer la variabilidad de genotipos para tener control sobre la transmisión de cepas, lo cual constituye un tópico de importancia en el sistema de salud y el mejoramiento de la calidad de vida de los pacientes.

Objective: Our aim was to analyze genotype and antimicrobial susceptibility of Pseudo-monas aeruginosa from cystic fibrosis patients and other diseases. Materials and methods: We analyzed 20 isolates from cystic fibrosis patients and 20 from patients with other diseases by dilution antimicrobial susceptibility test and random amplified polymorphic DNA technique. Results: We found that isolates from cystic fibrosis patients had higher resistance (56 %) than isolates from patients without cystic fibrosis (26 %). The most effective antimicrobi-als in both groups were cefepime, ceftriaxone and meropenem. With regard to the geno-type, we observed heterogeneity between strains from cystic fibrosis patients and two clus-ters with identical strains from hospital origin, suggesting a possible cross transmission. Conclusion: We concluded that the resistance rate of Pseudomonas aeruginosa in this study was high and this finding is accentuated in patients with cystic fibrosis, leaving few treatment options. Typification by random amplified polymorphic DNA technique allowed us to know the variability of genotypes to control strain transmission; this is an important topic to optimize health services and the quality of life of our patients.

DNA sequence homology analysis of Trichophyton rubrum isolates from multiple body sites of patients with onychomycosis / 中华皮肤科杂志

Objective To profile genotypes of Trichophyton rubrum isolates from different body sites in patients with onychomycosis. Methods DNA was extracted from 30 T. nibium isolates from 10 patients with onychomycosis, and subjected to PCR with tandemly repetitive subelement 1 (TRS1 )-specific primer to analyze the number of repetitive elements in the non-transcribed spacer (NTS) region of ribosomal DNA gene, and to random primer amplification with the random primer OPAA11. The genotype variety was evaluated for T. rubrum isolates from different body sites of patients with onychomycosis. Results All the strains were classified into 5 genotypes based on the copy number of TRS1, and into 11 genotypes by RAPD analysis. The genotypes of T. rubrum seemed unrelated to sites of infection. Genotype diversity was observed among T. rubrum strains from different body sites of the same host in 7 out of the 10 cases as shown by amplification of TRS1 region, in 8 out of the 10 cases as demonstrated by RAPD analysis. Conclusion A single host with onychomycosis could harbor multiple genotypes of T. rubrum at different body sites, suggesting external sources of infection rather than infection from a different site in the same individual.

Identificación de especies de Leishmania por la técnica de amplificación al azar del ADN polimórfico / Identification of Leishmania species by the random amplified polymorphic DNA technique

INTRODUCCIÓN: la leishmaniosis ha sido clasificada por la Organización Mundial de la Salud como una de las enfermedades tropicales más importantes. El control de esta parasitosis es muy difícil, porque no existen vacunas y el tratamiento es tóxico e insatisfactorio. Es de crucial importancia establecer un método de diagnóstico oportuno junto a la identificación del parásito, lo cual incide en la selección del tratamiento adecuado y en el diseño de las medidas de control apropiadas. Recientemente, los avances en biología molecular han permitido la caracterización de especies de Leishmania por diferentes métodos. La técnica de ADN polimórfico amplificado al azar es una técnica simple para detectar el polimorfismo genético del ADN. OBJETIVO: estandarizar la técnica de ADN polimórfico amplificado al azar para su utilización en la tipificación de especies de Leishmania del Nuevo Mundo. MÉTODOS: empleando una concentración de cebador de 5 pmol, 75 ng de ADN molde, 2 mM de cloruro de magnesio y 2 U de Taq ADN polimerasa en 25 mL de reacción, se obtuvieron patrones de amplificación reproducibles. La técnica optimizada de ADN polimórfico amplificado al azar se empleó para determinar las diferencias genéticas entre 10 cepas de referencia de Leishmania, con la utilización de 6 juegos de cebadores comerciales diseñados al azar. La relación filogenética entre las especies estudiadas se determinó utilizando la estrategia de agrupaciones mediante el método de UPGMA. RESULTADOS: los cebadores OPA 3, 4 y 8 permitieron diferenciar las 10 cepas de referencia de Leishmania estudiadas. Se obtuvieron 2 grupos genéticos bien definidos donde se agrupan las especies del subgénero Leishmania y Viannia, respectivamente; los 2 subgéneros mostraron diferencias genéticas. CONCLUSIONES: de esta forma se cuenta en el laboratorio con la técnica del ADN polimórfico amplificado al azar optimizada para la identificación de especies de Leishmania.

INTRODUCTION: leishmaniosis has been regarded by the World Health Organization as one of the most important tropical diseases. It is very difficult to control such parasitosis because there are not vaccines, and therapy is generally toxic and unsatisfactory. It is of vital importance to set prompt diagnostic method along with identification of the parasite in order to select the suitable treatment and to design the most convenient control measures. Recently, the advances in molecular biology have made it possible to characterize Leishmania species by different methods. The random amplified polymorphic DNA technique is a simple method to detect the genetic polymorphic DNA. OBJECTIVE: to standardize the random amplified polymorphic DNA technique for its use in New World Leishmania species typing. METHODS: by using 5 pmol primer concentration, 75 ng of template DNA, 2 mM of magnesium chloride and 2 U of polymerase DNA Taq in 25µL reaction, two reproducible amplification patters were obtained. The optimized random amplified polymorphic DNA technique served to determine the genetic differences among ten reference strains of Leishmania, with 6 sets of randomly designed conventional primers. The UP GMA method-based grouping strategy determined the phylogenetic relation among the studied species. RESULTS: OPA primers -3, 4 and 8 allowed distinguishing the ten reference strains of Leishmania under study. Two well defined genetic groups including species of Leishmania and Viannia subgenres were obtained; these 2 subgenres showed genetic differences. CONCLUSIONS: in this way, our laboratory has the optimized random amplified polymorphic DNA for the identification of Leishmania species.

Random amplified polymorphic DNA analysis of Malassezia isolates from cutaneous lesions of pityriasis versicolor / 中华皮肤科杂志

Objective To investigate intraspecific and interspecific variation within Malassezia iso-lates from patients with pityriasis versicolor by random amplified polymorphic DNA (RAPD) analysis, to learn the difference between RAPD analysis and physiological and biochemical methods in the typing of Malassezia species, and to explore the relationship between RAPD patterns and Malassezia species. Methods A total of 47 Malassezia isolates were obtained from 34 patients with pityriasis versicolor, and they were classified into 5 species by morphological, physiological and biochemical features, I.e., M. Fin'fur, M. Obtusa, M. Globosa, M. Restricta and M. Sympodialis. Genomic DNA was extracted from the 47 clinical isolates and 10 reference strains (including 7 species) of Malassezia. PCR was performed using 4 random primers including S22, S24, S25 and S33. RAPD patterns were analyzed by NTSYS software and dendrogram was autogenerated. Results Genomic DNA of most strains was successfully amplified with four primers, espe-cially with primers S22 and S24 that resulted in rather stable and clear DNA bands. A total of 82 fragments were amplified from all tested strains. These strains showed both interspecifie and intraspecific variation. Multiple swains were isolated from different body sites of 4 patients and identified into different species by biochemical and morphological typing; those swains from same hosts occupied contiguous positions in the dendrogram and exhibited a high genetic convergence. Conclusion The phenomenon that different strains from a co-host show a high genetic convergence indicates that species specificity and evolution of Malassezia are closely related to its hosts.

Genotyping and drug susceptability testing of Trichophyton rubrum isolated from children and adults with dermatophytosis / 中华皮肤科杂志

Objective To investigate the genotype of Trichophyton rubrum isolated from children and adults with dermatophytosis,and to explore the relationship between the genotype and location of lesions as well as drug susceptability of T.rubrum.Methods Dermatophytes were isolated from 67 children and 88 adults who had been diagnosed with dermatophytosis by microscopy and fongal culture.DNA was extracted from the clinical isolates of T. mbrum and random amplification of polymorphic DNA(RAPD)assay was performed with two random primers.i.e.,OPA11 5'ACCCGACCTC3'and OPD18 5'GAGAGCC AAC3',respectively.PCR products were subjected to electrophoresis to identify the genotypes of clinical isolates.Broth microdilution method was applied to assess the in vitro susceptibility of T. rubrum isolates to eight antifungal agents:fluconazole,itraconazole,terbinafine,ketoconazole,liranaflate,butenafine,econazole and bifonazole.Results T. rubrum was isolated from 47 children and 62 adults with dermatophytosis.RAPD assay yielded clear and stable DNA band profile.With primer OPA 11,these T.rubrum isolates were classified into 4 genotypes,i.e.,Ⅰ a,Ⅱ a,Ⅲa and Ⅳa.Both type Ⅰ a and Ⅲa represented 41.94%of the T. rubrmn isolates from adults,while type Ⅰa 65.96%of those from children;there was a significant difference in the genotype distribution between the two groups(P＜0.05).Also,the genotype distilbution was statistically different for tinea corporis and tinea pedis(P＜0.01,＜0.05 respectively)between adults and children,however,no significant difierence was observed for onychomycosis and tinea cruris(both P＞0.05).In vitro susceptibility test showed that all antifungal agents were effective against these T. rubrum isolates.Among these antifungals,terbinafine had the highest efficacy,and fluconazole exhibited the lowest effect against these isolates.Moreover,a higher efficacy was observed for ketoconazole and fluconazole against T. rubrum of type Ⅰ a than against other types of T. rubrum,and for bifonazole against T. rubrum isolates of type Ⅱ a than against other types.while the efficacy of itraconazole was lower against T. rubmm isolates of type Ⅲ a than against other types.Conclusions T. rubrum is the main pathogenic microorganism in adults and children with dermatophytosis.In adults,Ⅰ a and Ⅲ a are the predominate types of T. rubrum associated with dermatophytosis,while Ⅰ a is the common type in children.All the 8 antifungals tested have a good efficacy for various genotypes of T. rubrum,whereas the efficacy of fluconazole,itraconazole,kctoconazole,terbinafine and bifonazole varies with the genotypes of T. rubrum.

Genetics comparison on the Yersinia pestis strains of 3 kinds of ecotypes in the Sanjiangyuan area, Qinghai Province / 中国地方病学杂志

Objective To compare the genetic polymorphism of 34 Yersinia pest strains of 3 kinds of ecotypes(Microtus fiscis,Qilian Mountain and Qinghai-Tibet Plateau ecotype)that isolated from the Sanjiangyuan area in Qinghai Province and Shiqu County in Sichuan Province,in order to know the ecotype relationship among the strains.Methods Thirty-four strains were amplified using the application of random amplified polymorphism DNA(RAPD)and were detected with agaroge gel electmphoresis.Results Amplified products by ngarose gel electrophoresis method showed same stripes in 31 strains,only 3 strains had slight differences.Conclusion The Microtus fuscas,Qilian Mountain and Qinghai-Tibet Plateau ecotype strains isolated from Sanjiangyuan area are genetically homologous.

Caracterización de Klebsiella pneumoniae productora de la beta-lactamasa SHV-5, en una unidad de cuidados intensivos / Characterization of SHV-5 beta-lactamase-producing Klebsiella pneumoniae in an intensive care unit

OBJETIVO: Caracterizar molecularmente los aislamientos de Klebsiella pneumoniae obtenidos de pacientes pediátricos y del personal de salud en la unidad de cuidados intensivos de un hospital de tercer nivel de atención en la Ciudad de México, Distrito Federal. MATERIAL Y MÉTODOS: Se analizaron 15 aislamientos de Klebsiella pneumoniae colectadas de un brote durante el mes de junio de 1996, ocho de pacientes y siete de personal del Hospital Infantil de México. Los aislamientos fueron caracterizados por electroforesis en gel de campos pulsados (EGCP), amplificación azarosa del polimorfismo de ADN por reacción en cadena de la polimerasa (AAPD-PCR), y serotipificación, isoelectroenfoque de beta-lactamasas y secuenciación nucleotídica de productos de la reacción en cadena de la polimerasa. RESULTADOS: El serotipo predominante fue el 61 y correlacionó con los perfiles de AAPD-PCR y EGCP en 11 de los 15 aislamientos. Se identificó una clona predominante productora de SHV-5 con una alta letalidad. CONCLUSIONES: Las técnicas de biología molecular fueron herramientas muy útiles en la caracterización de la clona de K. pneumoniae identificada en pacientes y el personal hospitalario, que sugirieron una posible transmisión cruzada. Estos resultados ilustran que se debe apoyar el fortalecimiento de los programas de control para evitar la diseminación de infecciones nosocomiales en esa unidad en estudio.

OBJECTIVE: To perform the molecular characterization of Klebsiella pneumoniae isolates from pediatric patients and health care workers at the intensive care unit of a tertiary care hospital in Mexico City. MATERIAL AND METHODS: Fifteen Klebsiella pneumoniae isolates collected during an outbreak in June 1996 were analyzed; eight were from patients and seven from health care workers of Mexico's Children's Hospital. Characterization of isolates was carried out by pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and serotyping, beta-Lactamase isoelectric focusing (IEF), and nucleotide sequencing of PCR products. RESULTS: Serotype 61 was predominant and correlated with genomic fingerprints of RAPD and PFGE in 11 of 15 isolates. One SHV-5-producer predominant clone with a high case-fatality rate was identified. CONCLUSIONS: Molecular biology techniques are useful tools to characterize the K. pneumoniae clone isolated from patients and health care workers, suggesting potential cross-transmission. These data call for strengthening control programs to prevent dissemination of nosocomial infections in the studied hospital.

Characterization of Pseudallescheria boydii and Scedosporium apiospermum by Random Amplification of Polymorphic DNA Assay / 中华皮肤科杂志

Objective To investigate the DNA polymorphism of Pseudallescheria boydii and Scedosporium apiospermum and to analyze the relationship between random amplification of polymorphic DNA (RAPD) patterns and geographic origins.Methods The genomic DNAs of 13 Pseudallescheria boydii strains and 18 Scedosporium apiospermum strains isolated from 5 countries were amplified with RAPD technique.Results All strains tested were classified into 31 patterns by combination of the results obtained with 3 primers.The cluster tendency was identified based on species difference,namely,P.boydii or S.apiospermum strains,however,no such cluster tendency was revealed based on geographic origins of the most of strains,by dendrogram analysis.Conclusions The infraspecific variability of P.boydii and S.apiospermum is considerable.The cluster tendency of RAPD profiles is of consistency with morphological properties of P.boydii and S.apiospermum to some degree,however,is of no correlation with geographic origins of the pathogenic strains.

Homologous analysis of E.coli O_(157)∶H_7 by pulsed-field gel electrophoresis and random amplified polimorphic DNA / 中华传染病杂志

Objective To analyze the molecular epidemiological characteristics of E. coli O 157∶H 7 of Xuzhou, Jiangsu. Methods The virulence gene spectrum of E. coli O 157∶H 7 strains were analyzed by PCR and the homology of E. coli O 157∶H 7 strains were detected by PFGE and RAPD. Results In all E. coli O 157∶H 7 strains isolated from epidemic area, 100% possess Hly and eaeA gene, 95.35% possess SLT 2 gene, and 11.63% possess SLT 1 gene. The PFGE spectrum showed that the strains isolated from epidemic area were distinctively different from the strains isolated from Japan, and similar to but not identical with the standard strain 882364. The PFGE spectrum of strains isolated from epidemic area patients were identical with those of strains isolated from excrements of poultries, domestic animals and insect intestine.Conclusions Poultries and domestic animals which carry E.coli O 157∶H 7 could be the source of infection. PFGE could be used to analyze E.coli O 157∶H 7 and played an important role in epidemiology study. The results showed that the method of analysis of E. coli O 157∶H 7 by RAPD was convenient and time saving.

Comparison of single factor design and response surface design to optimize the reaction system for randomly amplified polymorphic DNA / 中华检验医学杂志

Objective To obtain optimum scheme on reaction system for randomly amplified polymorphic DNA(RAPD) of Pseudomonas aeruginosa. Methods The optimum reaction systems of RAPD were obtained by single factor design and response surface design(RSD). Results The multiple optimum reaction systems caused by effect of interaction on multifactor were observed in single factor design, and the concentrations of key components of the optimum reaction system with good stability obtained by response surface design were 2.0 mmol/L of Mg 2+ , 0.5 ?mol/L of primer and 0.5 ng/?l of template. Conclusion To optimize the reaction system of RAPD, RSD is simpler, more scientific, and more reasonable than single factor design.

Random Amplified Polymorphic DNA Analysis of the Genomes Among 7 Species of Ticks / 中国寄生虫学与寄生虫病杂志

Objective To study genomic polymorphic DNA and genetic distance of 7 species of ticks.\ Methods\ Ticks used in this study were Dermacentor nuttalli, D.silvarum, Haemaphysalis qinghaiensis, H.formosensis, H.punctata, Amblyomma testudinarium, and Ixodes ovatus. DNA extracts of the 7 species of ticks were amplified by random amplified polymorphic DNA (RAPD) and PCR technique using 5 primers with different arbitrary single chain polynucleotide sequences. DNA fingerprint maps were analyzed and the genetic distance among 7 species of ticks were counted. \ Results \ The amplified products of the 7 species of ticks by RAPD all showed their specific DNA band. The average genetic distance among them was 0^71. Conclusion RAPD can differentiate the 7 species of ticks.

RAPD Analysis on Different Isolates of Trichomonas vaginalis / 中国寄生虫学与寄生虫病杂志

Objective To study genetic polymorphism of DNA on seven isolates of Trichomonas vaginalis. Methods The random amplified polymorphic DNA (RAPD) technique was performed to amplify genomic DNA of the seven T. vaginalis isolates, including Beijing 1, Beijing 2, Chengde, Tangshan, Jiujiang 1, Jiujiang 2 and Jiujiang 3. The DNA bands detected were analyzed by clustering analysis with SPSS software. Results The percentage of genetic similarity among the seven isolates was from 77.4% to (94.7%,) showing a close genetic relationship among them. The percentages between the isolates of Beijing 1 and Tangshan, Jiujiang 1 and Jiujiang 2, Beijing 2 and Jiujiang 3 were 89.2%, 92.1% and 94.7% respectively, while that of Jiujiang1 and Chengde was 77.4%, indicating a lower homology. Conclusion There are a close genetic relationship and certain gene polymorphism among the seven T. vaginalis isolates; geographical origin plays little role to the genetic characteristics.