Genetic and Physiological Responses to Heat Stress in Brassica napus.

Given the current rise in global temperatures, heat stress has become a major abiotic challenge affecting the growth and development of various crops and reducing their productivity. Brassica napus, the second largest source of vegetable oil worldwide, experiences a drastic reduction in seed yield and quality in response to heat. This review outlines the latest research that explores the genetic and physiological impact of heat stress on different developmental stages of B. napus with a special attention to the reproductive stages of floral progression, organogenesis, and post flowering. Several studies have shown that extreme temperature fluctuations during these crucial periods have detrimental effects on the plant and often leading to impaired growth and reduced seed production. The underlying mechanisms of heat stress adaptations and associated key regulatory genes are discussed. Furthermore, an overview and the implications of the polyploidy nature of B. napus and the regulatory role of alternative splicing in forming a priming-induced heat-stress memory are presented. New insights into the dynamics of epigenetic modifications during heat stress are discussed. Interestingly, while such studies are scarce in B. napus, opposite trends in expression of key genetic and epigenetic components have been identified in different species and in cultivars within the same species under various abiotic stresses, suggesting a complex role of these genes and their regulation in heat stress tolerance mechanisms. Additionally, omics-based studies are discussed with emphasis on the transcriptome, proteome and metabolome of B. napus, to gain a systems level understanding of how heat stress alters its yield and quality traits. The combination of omics approaches has revealed crucial interactions and regulatory networks taking part in the complex machinery of heat stress tolerance. We identify key knowledge gaps regarding the impact of heat stress on B. napus during its yield determining reproductive stages, where in-depth analysis of this subject is still needed. A deeper knowledge of heat stress response components and mechanisms in tissue specific models would serve as a stepping-stone to gaining insights into the regulation of thermotolerance that takes place in this important crop species and support future breeding of heat tolerant crops.

Resistance of Streptococcus pneumoniae isolated from Lebanese patients between 2005 and 2009.

INTRODUCTION: Streptococcus pneumoniae is an important organism in view of its prevalence and ability to cause serious infections; its resistance to antimicrobial agents is increasing worldwide. The purpose of this study was to evaluate the patterns of resistance of S. pneumoniae to penicillin, macrolides and various other antibiotics in strains isolated from Lebanese patients. METHODS: 121 strains isolated between January 2005 and January 2009 from two university hospitals in Beirut were identified and tested for MIC determination using the E-test method. The presence of erm(B) and mef(A/E) genes was investigated using PCR. RESULTS: The majority of the strains (73.5%) were isolated from respiratory tract infections, 50.4% were isolated in winter, 15.7% were invasive strains, 61.9% came from male patients, and 68.5% from adults. Out of 121 isolates, 58 were susceptible to penicillin, 61 were intermediate, and 2 were fully resistant to this antibiotic. Amoxicillin-clavunanic acid and cefpodoxime showed 100% activity on all tested isolates. In general, the MICs90 appear to fluctuate within the same range over the four years. The erm(B) gene was detected in 85.3% of the isolates, mef(A/E) in 19.5% whereas erm(A) was not detected in any of the macrolide resistant strains. DISCUSSION: The results of this study have important impact on the empirical antibiotic prescriptions; the increasing prevalence of resistance jeopardises the treatment choices posing a serious threat. Further surveillance and epidemiological serotyping are needed to monitor the local and regional resistance patterns and to track the spread route of resistance.

Resistance of Streptococcus pneumoniae isolated from Lebanese patients between 2005 and 2009

Introducción: Streptococcus pneumoniae es un organismo importante en tanto la prevalencia como la capacidad de causar infecciones graves; su resistencia a los antibióticos es cada vez mayor en todo el mundo. El objetivo de este trabajo fue evaluar los modelos de resistencia de S. pneumoniae a penicilina, macrólidos y varios otros antibióticos en cepas aisladas de pacientes libaneses. Métodos: 121 cepas aisladas entre enero de 2005 y enero de 2009 en dos hospitales universitarios en Beirut se identificaron y comprobaron para la determinación de la concentración mínima inhibitoria por el método E-test. La presencia de los genes erm(B) y mef(A/E) investigó mediante PCR. Resultados: La mayoría de las cepas fueron aisladas de infecciones del tracto respiratorio (73,5%). Cincuenta con cuatro por cien fueron aislados en el invierno, 15,7% fueron cepas invasivas, 61,9% procedían de pacientes de sexo masculino, y un 68,5% de adultos. De los 121 aislamientos, 58 fueron susceptibles a la penicilina, 61 fueron intermedios, y 2 fueron completamente resistentes a este antibiótico. Amoxicilina-ácido clavulánico y cefpodoxima mostraron 100% de actividad en todos los aislamientos estudiados. En general, las CMIs90 parecen fluctuar dentro del mismo rango en los cuatro años. El gen erm(B) se detectó en el 85,3% de los aislamientos, mef(A/E) en 19,5%, mientras que erm(A) no se detectó en ninguna de las cepas resistentes a macrólidos. Discusión: Los resultados de este estudio tienen un gran impacto en la prescripción antibiótica empírica en el Líbano. Una mejor vigilancia epidemiológica acompañada de un serotipado es imprescindible para el futuro(AU)

Introduction: Streptococcus pneumoniae is an important organism in view of its prevalence and ability to cause serious infections; its resistance to antimicrobial agents is increasing worldwide. The purpose of this study was to evaluate the patterns of resistance of S. pneumoniae to penicillin, macrolides and various other antibiotics in strains isolated from Lebanese patients. Methods: 121 strains isolated between January 2005 and January 2009 from two university hospitals in Beirut were identified and tested for MIC determination using the E-test method. The presence of erm(B) and mef(A/E) genes was investigated using PCR. Results: The majority of the strains (73.5%) were isolated from respiratory tract infections, 50.4% were isolated in winter, 15.7% were invasive strains, 61.9% came from male patients, and 68.5% from adults. Out of 121 isolates, 58 were susceptible to penicillin, 61 were intermediate, and 2 were fully resistant to this antibiotic. Amoxicillin-clavunanic acid and cefpodoxime showed 100% activity on all tested isolates. In general, the MICs90 appear to fluctuate within the same range over the four years. The erm(B) gene was detected in 85.3% of the isolates, mef(A/E) in 19.5% whereas erm(A) was not detected in any of the macrolide resistant strains. Discussion: The results of this study have important impact on the empirical antibiotic prescriptions; the increasing prevalence of resistance jeopardises the treatment choices posing a serious threat. Further surveillance and epidemiological serotyping are needed to monitor the local and regional resistance patterns and to track the spread route of resistance(AU)