Green mathematics: Benefits of including biological variation in your data analysis
Biological variation is omnipresent in nature. It contains useful information that is neglected by the usually applied statistical procedures. To extract this information special procedures have to be applied. Biological variation is seen in properties (e.g. size, colour, firmness), but the underlying issue is almost always to the variation in development or maturity in a batch of individuals generated by small scale environmental differences. The principles of assessing biological variation in batches of individuals are explained without putting emphasis on mathematical details. Obtained explained parts increase from about 60 to 80 % for the usual approach to 95 when the biological variation is taken into account. When technical variation or measuring error is small even 99 % can be achieved. The benefit of the presented technology is highlighted based on a number of already published studies covering the colour of apples during growth and storage and the firmness of cut tomatoes during storage.
The impact of biological variation on postharvest population dynamics
Abstract This paper outlines a mathematical approach to the interpretation of postharvest batch behaviour based on the underlying processes occurring at the level of the individual food items and on the amount of biological variation present. This technique opens the door to a mechanistic interpretation of postharvest batch behaviour, both qualitative and quantitative, enabling the postharvest industries to improve their control of the quality of their produce throughout the postharvest chain. The generic approach is outlined and applied to case studies on shrivelling of ‘Braeburn’ apples, the colour change of ‘Hass’ avocados and stress crack development in corn grains.
Coexistence of Virulence and Antibiotic Resistance Genes in Pasteurella multocida Isolated from Diseased Rabbits
Pasteurella multocida (P. multocida)is considered a predominant pathogenic bacterial agent causing respiratory manifestations (snuffles) in rabbits with considerable economic losses and unfavorable prognosis in Egypt. A few recent P. multocida strains exhibit resistance to the most commonly used antibiotics in the veterinary field. Therefore, the present study was carried out to investigate the prevalence of both virulence and antibiotic resistance genes among P. multocida isolated from diseased rabbits in Sharkia Governorate, Egypt. Only 10 out of 100 tested rabbits` nasal swabs were finally confirmed positive for P. multocida of serogroup A by polymerase chain reaction (PCR). Antibiotic susceptibility testing of the recovered isolates revealed that they were all multidrug resistant (MDR) with a predominance of resistance to amoxicillin, ampicillin, amoxicillin/clavulanic acid, neomycin and tetracycline (100% each), followed by kanamycin and streptomycin (90% each). All the recovered isolates were further subjected to PCR screening of some common virulence and antibiotic resistance genes of interest . With the exception of toxA gene, the other virulence associated genes (ptfA, Omp87 and nanB) were found among all the examined isolates. Totally, all MDR P. multocida isolates contained at least one antibiotic resistance gene with aphA1 being the most prevalent (100%), followed by ermX gene (40%). Antibiotic resistance genotyping demonstrated the presence of multiple antibiotic resistance genes among majority of the isolates (40%) with only one isolate harboring 4 genes encoding identical resistance phenotypes. Evidentially, all MDR P. multocida isolates possessed at least 3 virulence genes accompanied by the attendance of antibiotic resistance genes. These findings evidenced that rabbits are potential sources of pathogenic P. multocida strains harboring virulence and antibiotic resistance genes. Therefore, it is evident that there is an urgent need for the judicious use of antibiotics in rabbits` treatment systems to successfully mitigate the propagation of drug resistance across P. multocida species.