Genetic homogeneity within Leishmania (L.) infantum isolated from human and dogs: the relationship with the sandfly fauna distribution in endemic areas of Nueva Esparta State, Venezuela

Parasitology ◽  
2005 ◽  
Vol 130 (6) ◽  
pp. 611-619 ◽  
Author(s):  
N. M. RODRIGUEZ ◽  
Z. DE GUGLIELMO ◽  
M. A. BARRIOS ◽  
R. M. BARRIOS ◽  
O. ZERPA ◽  
...  

Leishmania infantum has been described as a highly polymorphic group of parasites, responsible for visceral leishmaniasis and cutaneous leishmaniasis. In this paper we report the life-cycle of L. (L.) infantum in an endemic area of visceral leishmaniasis in Venezuela, by using molecular diagnosis and characterization of parasites isolated from dogs, humans with visceral leishmaniasis and sand flies. The molecular characterization was carried out by use of kDNA restriction analysis, dot-blot hybridization with species-specific probes and RFLP of the PCR products. The results demonstrated that L. (L.) infantum is the parasite responsible for VL in the island. The parasites were revealed to be genetically homogeneous with no intra-specific differences between isolates from different individuals. The highest homology of the isolates was with L. (L.) infantum from the Old World rather than with L. (L.) chagasi from the New World. Additionally, we report the geographical distribution of Lutzomyia longipalpis, and the relationship with the transmission of L. (L.) infantum in the studied area.

1998 ◽  
Vol 64 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Sunny C. Jiang ◽  
Christina A. Kellogg ◽  
John H. Paul

ABSTRACT To understand the ecological and genetic role of viruses in the marine environment, it is critical to know the infectivity of viruses and the types of interactions that occur between marine viruses and their hosts. We isolated four marine phages from turbid plaques by using four indigenous bacterial hosts obtained from concentrated water samples from Mamala Bay, Oahu, Hawaii. Two of the rod-shaped bacterial hosts were identified as Sphingomonas paucimobilis andFlavobacterium sp. All of the phage isolates were tailed phages and contained double-stranded DNA. Two of the phage isolates had morphologies typical of the family Siphoviridae, while the other two belonged to the families Myoviridae andPodoviridae. The head diameters of these viruses ranged from 47 to 70.7 nm, and the tail lengths ranged from 12 to 146 nm. The burst sizes ranged from 7.8 to 240 phage/bacterial cell, and the genome sizes, as determined by restriction digestion, ranged from 36 to 112 kb. The members of the Siphoviridae, T-φHSIC, and T-φD0, and the member of the Myoviridae, T-φD1B, were found to form lysogenic associations with their bacterial hosts, which were isolated from the same water samples. Hybridization of phage T-φHSIC probe with lysogenic host genomic DNA was observed in dot blot hybridization experiments, indicating that prophage T-φHSIC was integrated within the host genome. These phage-host systems are available for use in studies of marine lysogeny and transduction.


Plant Disease ◽  
1999 ◽  
Vol 83 (4) ◽  
pp. 390-395 ◽  
Author(s):  
M. L. Xu ◽  
A. E. Melchinger ◽  
T. Lübberstedt

Head smut of maize, caused by Sporisorium reiliana, may substantially reduce grain yield. The objective of the present study was to develop a highly specific and sensitive DNA-based assay for detection of S. reiliana and its differentiation from Ustilago maydis, a maize fungus inducing the symptomatically similar common smut disease. Plasmid libraries of S. reiliana and U. maydis were constructed using a shotgun cloning procedure. Clones containing strongly hybridizing species-specific DNA were selected by screening libraries with their own labeled genomic DNA, followed by cross-hybridization with genomic DNA of maize and other maize-pathogenic fungi. The selected clones were used to generate subclones with short insert fragments to facilitate PCR amplification for labeling and primer design for a PCR assay. Using Dig-dUTP labeled inserts, detection of less than 0.16 ng of fungal DNA was possible by dot blot hybridization. Sequences of insert fragments were determined to design primer pairs for a PCR-based assay. Primer pairs SR1 and SR3 are species-specific for S. reiliana, and UM11 is species-specific for U. maydis. The PCR-based assays can detect fungal DNA of less than 1.6 pg using SR1 and SR3, and 8 pg using UM11, irrespective of the presence of maize DNA. Use of SR1 and SR3 allowed detection of S. reiliana in the extracts of pith, node, and shank from S. reiliana-infected plants, but not in leaves. Thus, both the dot blot hybridization and the PCR-based assays provide a highly sensitive and reliable tool for detection and differentiation of corn smut caused either by S. reiliana or by U. maydis.


Parasitology ◽  
1988 ◽  
Vol 97 (1) ◽  
pp. 63-73 ◽  
Author(s):  
W. C. Gibson ◽  
P. Dukes ◽  
J. K. Gashumba

SUMMARYWe have obtained 5 specific DNA probes for African trypanosomes of the subgenera Trypanozoon and Nannomonas. Each probe consists of one repeat unit of the major repetitive DNA (satellite DNA) of each species or intra-specific group. One probe hybridized with all members of subgenus Trypanozoon (except T. equiperdum which was not tested). In subgenus Nannomonas, one probe recognized T. simiae, but 3 probes were needed to identify all stocks of T. congolense available. Each of the 3 latter probes recognized trypanosomes from one of the 3 major groups of T. congolense previously defined by isoenzyme characterization, i.e. savannah, forest and Kenya coast types. As few as 100 trypanosomes could be unequivocally identified by dot blot hybridization and individual trypanosomes could be identified by in situ hybridization. We show how this simple methodology can be used in the field for the identification of immature and mature trypanosome infections in tsetse.


2005 ◽  
Vol 85 (2) ◽  
pp. 309-316
Author(s):  
Fa-Yun Zhang ◽  
Wei-Bo Yin ◽  
Rui Shi ◽  
Ying-Kao Hu ◽  
Yue-Ming Yan ◽  
...  

Chromosome 1B was microdissected and collected from chromosome spreads of wheat (Triticum aestivum L. ‘Jing 411’), using a glass needle. DNA of the isolated chromosome was amplified in vitro by Sau3A linker adaptor-mediated polymerase chain reaction (LA-PCR). The second-round PCR products were verified by Southern hybridization using DIG-labeled genomic DNA of wheat. The results initially showed the DNA was from wheat genome. A pair of SSR primers specific to chromosome 1B was used to verify the origin of the PCR products from the isolated chromosome. The results confirmed that the PCR products originated from chromosome 1B. The second round of PCR products from chromosome 1B were cloned into plasmid pUCm-T vectors to create a chromosome-specific library, which included approximately 248 000 recombinant clones. Characterization of 100 randomly selected clones of the library showed that the insert size ranged between 0.5 and 2.0 kb, with an average of 1 kb. Randomly selected 288 clones were characterized with dot blot hybridization, of which 57.2% were medium/high copy clones and 42.8% low/single copy clones. The application of this technique to establish high-density molecular maps for chromosome 1B is discussed. Key words: Wheat, chromosome microdissection, chromosome-specific library


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