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1.
Plant Dis ; 91(3): 328, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30780586

RESUMO

Since 2000, a phytoplasma-like disease (locally known as "permanent yellowing") was observed on tomatoes (Lycopersicon esculentum Mill.) grown in the Valle de San Quintín in northern Baja California Peninsula. Affected plants showed general chlorosis, severe stunting, upwardly rolled leaves, bronzing of mature leaves, purple discoloration of veins, "little leaf", abnormal floral structures, and excessive branching of axillary shoots. Total DNA extracted from symptomatic and asymptomatic plants was used in nested (n)-PCR assays driven by phytoplasma-universal primer pair P1/P7 (3), followed by primer pair R16F2n/R16R2 (1) targeting the 16S ribosomal RNA gene of the putative phytoplasma. PCR conditions (direct and nested) were conducted as previously described (l,3). Restriction fragment length polymorphism (RFLP) patterns of nPCR-amplified products (≈ 1.25-kbp 16S rDNA fragments) digested with enzymes AluI, MseI, HhaI, and HpaII showed that 85% (17 of 20) of PCR-positive tomato samples had restriction patterns typical of phytoplasmas belonging to the aster yellows group, subgroup B (16SrI-B) "Candidatus Phytoplasma asteris" (2). Only 10% (2 of 20) of the samples were associated with a phytoplasma related to the 16SrXIII-A Mexican periwinkle virescence group (formerly group 16SrI, subgroup I). None of the symptomless plants tested positive. Subsequently, these results were confirmed by nPCR using 16SrI specific primer pair P1/Aint (4) and specific primers rp(I-B)F1/rp(I-B)R1 that amplify the ribosomal protein (rp) gene operon of aster yellows phytoplasma subgroup B (16SrI-B[rp-B]) (1). The presence of the phytoplasmas in symptomatic plants was confirmed by scanning electron microscopy. Characteristic yellow symptoms could be experimentally reproduced by graft inoculation of tomato seedlings (cv. Maya) with tissue of field-infected plants. Symptoms similar to those of field-grown diseased plants were observed consistently in most of the plants, and when graft transmitted from tomato to periwinkle (Catharantus roseus (L.) G. Don), symptoms of virescencent, small flowers were observed. In contrast, no symptoms were observed on plants grafted with tissues from healthy plants. In Baja California, it appears that at least two distinct phytoplasmas are involved in the disease complex. To our knowledge, this is the first molecular evidence of the presence of a phytoplasma associated with yellows-type diseases in the major tomato cultivation areas of the peninsula. References: (1) I.-M. Lee et al. Phytopathology 93:1368, 2003. (2) I.-M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:1037, 2004. (3) B. Schneider et al. Page 369 in: Molecular and Diagnostic Procedures in Mycoplasmology. Academic Press, San Diego, CA, 1995. (4) C. D. Smart et al. Appl. Environ. Microbiol. 62:2988, 1996.

2.
Clin Diagn Lab Immunol ; 7(6): 945-6, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11063503

RESUMO

Preserving blood samples for shipping and later DNA extraction has been performed by cooling, freezing, drying, freeze-drying, and protease treatment, among other methods. Most methods to preserve field samples for further DNA extraction do not prevent cellular and DNA damage or are useful only in preserving them for short periods. This report introduces a novel method for blood and tissue that allows preservation in freezing temperatures for a prolonged period of time. The solution reported here (20% ethylene glycol-propylene glycol) preserves cells and tissues integrity, as judged by microscopic analysis, and improves DNA yield and quality.


Assuntos
Preservação de Sangue/métodos , Criopreservação/métodos , Crioprotetores , DNA/isolamento & purificação , Preservação de Tecido/métodos , Coleta de Amostras Sanguíneas , Medula Óssea , Etilenoglicol , Humanos , Propilenoglicol
3.
Gene ; 253(2): 303-11, 2000 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-10940568

RESUMO

S1 mapping showed that at least a significant portion of the 5S rRNA and tRNA(Arg)(ACG) is co-transcribed in canola chloroplast, making trnR the last gene transcribed in an operon of which the final sequence is 5'-16S-tRNA(Ile)-tRNA(Ala)-23S-4.5S-5S-tRNA(Arg)-3'. Various RNA termini representing RNA processing sites at several parts of the 5S rRNA-tRNA(Arg) area were detected. This gene spacer is substantially conserved among various species compared here, and a secondary structure model for this chloroplast region in canola applies to other plant sequences. The conservation of this intergenic sequence suggests a functional role, possibly by providing recognition structures for endogenous RNases involved in its maturing process.


Assuntos
Brassica/genética , Cloroplastos/genética , Processamento Pós-Transcricional do RNA , RNA Ribossômico 5S/genética , RNA de Transferência de Arginina/genética , Sequência de Bases , DNA Ribossômico/química , DNA Ribossômico/genética , Modelos Moleculares , Dados de Sequência Molecular , Estrutura Molecular , Conformação de Ácido Nucleico , RNA de Plantas/genética , RNA de Plantas/fisiologia , RNA de Transferência de Arginina/química , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Transcrição Gênica
4.
Vet Microbiol ; 75(1): 91-7, 2000 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-10865155

RESUMO

The polymerase chain reaction (PCR) was used to diagnose goat brucellosis and compare its sensitivity against some of the most commonly used serological and bacteriological techniques. Twenty two female and one male out of 300 clinically healthy, mixed-breed goats were randomly chosen from a ranch located at Marín, Nuevo León, Mexico. Milk and blood samples were taken from each animal and used to obtain both microbiological cultures and DNA of the pathogen, and sera was tested against Rose Bengal antigen (RBT). Results showed that 86% of the blood samples were positive on the PCR test, while 60% were positive on the serological test. The pathogen was isolated from only one blood culture. Sixty four percent of the milk samples were positive on PCR tests, but failed to yield bacteria in culture. Biochemical and PCR specific assay demonstrated that Brucella abortus biovar 1 was associated with the infection. This study demonstrates the higher sensitivity of PCR over RBT and blood culture and its potential towards a rapid identification of Brucella strains.


Assuntos
Brucella abortus/isolamento & purificação , Brucelose/veterinária , Doenças das Cabras/diagnóstico , Reação em Cadeia da Polimerase/veterinária , Testes de Aglutinação/veterinária , Animais , Brucella abortus/química , Brucella abortus/genética , Brucelose/sangue , Brucelose/diagnóstico , Brucelose/microbiologia , Primers do DNA/química , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , Eletroforese em Gel de Ágar/veterinária , Eletroforese em Gel de Poliacrilamida/veterinária , Feminino , Doenças das Cabras/microbiologia , Cabras , Masculino , Leite/microbiologia , Reação em Cadeia da Polimerase/métodos , Rosa Bengala/química , Sensibilidade e Especificidade
6.
Plant Cell Rep ; 19(7): 667-673, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30754803

RESUMO

BRASSICA NAPUS: can be applied to other known plant sequences. The conservation of those sequences suggests a functional role for them possibly by providing recognition structures for endogenous RNases involved in the 4.5S rRNA-5S rRNA maturing process. Most of the processing signals detected here are located at single-stranded regions of a proposed secondary structure.

7.
Proc Natl Acad Sci U S A ; 93(18): 9397-401, 1996 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-8790341

RESUMO

The potato spindle tuber disease was first observed early in the 20th century in the northeastern United States and shown, in 1971, to be incited by a viroid, potato spindle tuber viroid (PSTVd). No wild-plant PSTVd reservoirs have been identified; thus, the initial source of PSTVd infecting potatoes has remained a mystery. Several variants of a novel viroid, designated Mexican papita viroid (MPVd), have now been isolated from Solanum cardiophyllum Lindl. (papita güera, cimantli) plants growing wild in the Mexican state of Aguascalientes. MPVd's nucleotide sequence is most closely related to those of the tomato planta macho viroid (TPMVd) and PSTVd. From TPMVd, MPVd may be distinguished on the basis of biological properties, such as replication and symptom formation in certain differential hosts. Phylogenetic and ecological data indicate that MPVd and certain viroids now affecting crop plants, such as TPMVd, PSTVd, and possibly others, have a common ancestor. We hypothesize that commercial potatoes grown in the United States have become viroid-infected by chance transfer of MPVd or a similar viroid from endemically infected wild solanaceous plants imported from Mexico as germplasm, conceivably from plants known to have been introduced from Mexico to the United States late in the 19th century in efforts to identify genetic resistance to the potato late blight fungus, Phytophthora infestans.


Assuntos
Doenças das Plantas/genética , Vírus de Plantas/genética , Solanum tuberosum , Viroides/genética , Sequência de Bases , DNA Viral/química , Eletroforese em Gel de Poliacrilamida , Dados de Sequência Molecular , Homologia de Sequência do Ácido Nucleico , Software
8.
J Clin Microbiol ; 33(12): 3087-90, 1995 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8586678

RESUMO

A versatile method for the extraction of Brucella DNA and PCR are presented as reliable tools for the detection of Brucella spp. from body fluids of infected animals. Two oligonucleotides homologous to regions of the gene encoding for an outer membrane protein (omp-2) were designed to detect the pathogen from milk and/or blood of infected goats, bovines, and human patients. The sensitivity of our test and its ability to detect the pathogen in samples from the field reveal a promising advance in the diagnosis of brucellosis in animals and humans.


Assuntos
Sangue/microbiologia , Brucella/genética , Brucella/isolamento & purificação , Leite/microbiologia , Reação em Cadeia da Polimerase/métodos , Animais , Proteínas da Membrana Bacteriana Externa/genética , Sequência de Bases , Brucella/classificação , Brucella abortus/genética , Brucella abortus/isolamento & purificação , Brucella melitensis/genética , Brucella melitensis/isolamento & purificação , Brucelose/diagnóstico , Brucelose/veterinária , Bovinos , Primers do DNA/genética , DNA Bacteriano/sangue , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Feminino , Genes Bacterianos , Cabras , Humanos , Leite Humano/microbiologia , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/estatística & dados numéricos , Sensibilidade e Especificidade
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