Colonization dynamic of various crop residues by Fusarium graminearum monitored through real-time PCR measurements.

AIMS: To evaluate the effect of the type of crop residues on the colonization dynamic of Fusarium graminearum in soil. METHODS AND RESULTS: The ability of F. graminearum to survive in the presence of various crop residues was assessed on Petri dishes and in microcosms. These microcosms comprised soil that had or had not been previously disinfested with or without amendment with various crop residues. The colonization dynamic of F. graminearum was monitored through real-time PCR. Fusarium graminearum development was higher in disinfested soil than in non-disinfested one. The fungal growth was enhanced to various extents according to the type of crop residues, except for mustard residues which inhibited it. The biochemical and physical properties of the residues were likely to account for the differences in the survival of F. graminearum. CONCLUSIONS: Fusarium graminearum is a poor competitor in soil but it can use maize, wheat, and rape residues to ensure its survival. Conversely alfalfa, which is assimilated by micro-organisms very easily, avoids long-lasting survival of the fungus. And finally, mustard producing glucosinolates could be used as an intermediate crop to reduce the inoculum amount. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is contributing to the knowledge about F. graminearum saprotophic abilities and proposes interesting paths to limit its survival in soil.

Bi-fluorescence imaging for estimating accurately the nuclear condition of Rhizoctonia spp.

AIMS: To simplify the determination of the nuclear condition of the pathogenic Rhizoctonia, which currently needs to be performed either using two fluorescent dyes, thus more costly and time-consuming, or using only one fluorescent dye, thus less accurate. METHODS AND RESULTS: A red primary fluorescence (autofluorescence) of the hyphal cell walls and septa of Rhizoctonia spp. with green excitation is evidenced in Rhizoctonia spp. This property is exploited and combined for the first time with a conventional DAPI fluorescence to accurately determine the nuclear condition of Rhizoctonia. This bi-fluorescence imaging strategy depicted the nuclear condition in Rhizoctonia spp. more accurately than the conventional DAPI fluorescence used alone and was validated against isolates previously genotyped by DNA sequencing. CONCLUSIONS: We demonstrated that the bi-fluorescence imaging strategy was safe, accurate and simple to perform and interpret. SIGNIFICANCE AND IMPACT OF THE STUDY: The developed bi-fluorescence imaging strategy provides a sensitive tool for determining the nuclear condition of Rhizoctonia strains. Its simplicity is a key advantage when there are numerous cultures to be examined.

[Low-density lipoprotein cholesterol levels in hypercholesterolemic rabbits with or without carbon monoxide poisoning]. / Teneur en cholestérol des lipoprotéines légères chez le lapin hypercholestérolémique intoxiqué ou non par l'oxyde de carbone.

Low-density lipoproteins isolated by a selective precipitation procedure have been investigated in cholesterol-fed rabbits exposed or not to carbon monoxide. The main findings are a higher increase of their cholesterol content and cholesterol to phospholipid molar ratio without a modification in lecithin-cholesterol-acyltransferase activity in intoxicated animals. Thus, the aggravating effect of carbon monoxide exposure on the atherogenic properties of these lipoproteins could accelerate the development of atherosclerosis in cholesterol-fed rabbits.