Diana Sara Leal-Klevezas

Use of polymerase chain reaction to detect Brucella abortus biovar 1 in infected goats.

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.

Antifreeze Solution Improves DNA Recovery by Preserving the Integrity of Pathogen-Infected Blood and Other Tissues

ABSTRACT 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.

Genotyping of Ochrobactrum spp. by AFLP Analysis

AFLP was used to analyze the genetic diversity among Ochrobactrum strains. AFLP patterns showed a great genomic variability that separated the samples into three distinct clusters. Ochrobactrum intermedium was found to be closely related to Brucella abortus S99.

Transcription and processing map of the 4.5S-5S rRNA intergenic region (ITS3) from rapeseed (Brassica napus) chloroplasts

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.

Transgenes in Mexican maize

To the editor: Genetic flow between transgenic and native maize has apparently occurred in Mexico1, resulting in wild strains containing one or more transgenic sequences (most likely encoding Bt toxin). These “transgenic” native maizes not only have every single trait that has been selected and preserved for thousands of years (making them perfectly adapted to specific geographic regions), but now also possess an additional and desirable characteristic— insect resistance, a trait likely to be consciously preferred by Mexican peasant farmers. Diversity will not be affected. On the contrary, we can predict that this useful transgene will be found in increasing numbers and types of native maizes. We believe it is important to stress this is not genetic contamination! Contamination means unexpected, undesirable, and uncontrollable spread; that is not happening. The spread will be induced because of the advantage of having a native corn with resistance to insects. Maize is so dependent on human intervention that it cannot survive in the wild. Maize seeds are attached to a cob and cannot free themselves: it absolutely requires human intervention. As maize was first domesticated more than 6,000 years ago, only genes and alleles that are important for humans have been selected and preserved. Still, if someone wants to remove the transgene from these plants, the procedure would be simple: select and multiply those susceptible maizes and do not harvest and multiply the insect-resistant ones. That is something no Mexican farmer will do. Teosintes, ancestors and close relatives of corn, do not seem to be affected by genetic flow from (any) maize. Teosintes growing naturally in cornfields yield a very poor hybrid progeny. They do not release their seeds, and therefore the probability is very low for natural genetic introgression (incorporation of a gene or allele in a population) into teosintes. We also have found that teosintes are highly susceptible to insects and pathogens when growing under more intensive experimental field conditions, but they appear to be resistant to them when growing naturally in the wild. Thus we conclude that even if the Bt transgene could be introgressed into teosintes, it will provide no biological advantage and thus would be lost by natural evolution. To reiterate2, there is no need for concern. Juan Pablo Ricardo Martínez-Soriano and Ana María Bailey, Unidad de Biotecnología e Ingeniería Genética de Plantas, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 629, 36500 Irapuato, Gto, México (jpms@ira.cinvestav.mx) Joel Lara-Reyna,Instituto de Fitosanidad,Colegio de Postgraduados,Montecillo, Edo de México, México, and Diana Sara Leal-Klevezas Secretaría de Salud de Guanajuato, Tamazuca 4 Centro, Guanajuato, Gto., México