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Artificial Media (artificial + media)

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Life Sciences100%

Selected Abstracts

Biological and biochemical differences between in vitro- and in vivo-reared Exorista larvarum

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006
Maria Luisa Dindo
Abstract Quantitative and qualitative parameters of Exorista larvarum (L.) (Diptera: Tachinidae) reared on two insect-material-free artificial media and in the factitious host Galleria mellonella L. (Lepidoptera: Pyralidae) were compared. Significantly higher puparial yields and weights were obtained in both a milk-based and a veal homogenate-based medium than in the factitious host. Longevity and parasitization rates were not different between the in vitro- and in vivo-reared flies. Despite the greater puparial weight of the veal medium-reared E. larvarum females, the number of eggs laid by these females on host larvae was not higher than that of females reared under the other two rearing conditions. Moreover, in a complementary experiment, with homogeneous puparial weights of milk medium- and host-reared females, the former oviposited fewer eggs. Hence, puparial weight alone is not a reliable quality parameter for E. larvarum reared on artificial media. Lower amino acid content, with a deficiency in aromatic amino acids and an excess in proline, was found for in vitro third instar parasitoid larvae reared on both media compared to the in vivo-reared ones. These results suggest a correlation between the amino acid deficiency and imbalance of medium-reared larvae and the lower number of eggs laid by the females obtained. [source]

Nutrition influences growth and virulence of the insect-pathogenic fungus Metarhizium anisopliae

FEMS MICROBIOLOGY LETTERS, Issue 2 2005
Farooq A. Shah
Abstract Nutrition influenced growth, sporulation and virulence of the insect pathogenic fungus, Metarhizium anisopliae. Virulent conidia were produced on susceptible insect hosts, 1% yeast extract, 2% peptone, osmotic stress medium (OSM) and CN 10:1 medium. Several strain independent markers were identified that could be used to predict the virulence of M. anisopliae conidia. Virulent conidia typically had high levels of spore bound Pr1, an important cuticle degrading protease, and high germination rates. We also show for the first time that virulent conidia have an endogenous CN ratio below 5.2:1. Real Time PCR revealed that virulent conidia from insects contained significantly higher levels of transcripts of pr1 A and other pathogenicity-related genes than inoculum from artificial media. Of the artificial media studied, 1% yeast extract medium yielded the most virulent conidia, these had higher levels of transcripts of these pathogenicity-related genes than the least virulent conidia from the high conidia yielding CN 35:1 medium (= SDA), however, the levels were significantly lower than those in insect-derived conidia. Our study shows for the first time that the passaged inoculum is virulent irrespective of the original culture medium or insect host. Virulent conidia were consistently produced on OSM even though growth and sporulation were poor. We postulate that starvation conditions, whether in vivo or in vitro, results in de-repression of Pr1 and that elevated levels of this enzyme enhance fungal virulence. [source]

The use of the green fluorescent protein as a biomarker for sapstain fungi

FOREST PATHOLOGY, Issue 3 2002
S. LEE
To understand wood colonization by sapstain fungi and their potential biocontrol agents, it is necessary to differentiate these organisms directly on their natural substrates. In the present study the feasibility of transforming with the green fluorescent protein (GFP), the sapstain fungus Ophiostoma piceae and a potential biocontrol agent Cartapip®, an Ophiostoma piliferum albino strain was assessed. Transformants of the two fungal species were screened by polymerase chain reaction and Southern blot analyses. The GFP was expressed in spores, synnemata and mycelia of the transformants grown in artificial media or wood. The growth, pigmentation and wood colonization of the transformants were similar to that of the non-transformants, suggesting that the presence of the gfp gene had no negative effect on the biology of the transformants. Using fluorescence and confocal microscopy, the GFP-expressing fungi were easily differentiated from the wild-type strains and other fungal species in wood, even 4 months after inoculation. The results show that the use of the GFP system is feasible to monitor Ophiostoma fungi in wood. Utilisation de la protéine fluorescente verte (GFP) comme marqueur biologique des champignons de bleuissement du bois Pour comprendre la colonisation du bois par les champignons de bleuissement et par les agents de lutte biologique potentiels, il est nécessaire de distinguer ces organismes directement dans leur substrat naturel. Nous avons évalué la possibilité de transformation par la protéine fluorescente verte (GFP) du champignon de bleuissement Ophiostoma piceae et d'une souche albinos de Ophiostoma piliferum, agent de lutte biologique potentiel Cartapip®. Des transformants des deux espèces fongiques ont été triés par analyses PCR et Southern blot. La GFP a été exprimée dans les spores, les synnemas et le mycélium des transformants cultivés sur milieux artificiels et sur bois. Avec les transformants, la croissance, la pigmentation et la colonisation du bois étaient semblables à celles des non transformants, ce qui suggère que la présence du gène gfp n'a pas d'effet négatif sur la biologie des transformants. Par microscopie confocale à fluorescence, les champignons exprimant la GFP ont été facilement distingués des souches de type sauvage et d'autres espèces fongiques dans le bois, même 4 mois après inoculation. Nos résultats montrent que l'utilisation de la GFP est possible pour suivre les Ophiostoma dans le bois. Verwendung des Grünen Fluoreszenzproteins als Biomarker für Bläuepilze Um die Besiedelung von Holz durch Bläuepilze und ihre möglichen Antagonisten zu verstehen, muss man diese Organismen direkt auf ihrem natürlichen Substrat unterscheiden können. Es wurde überprüft, ob sich der Bläuepilze Ophiostoma piceae und der mögliche Antagonist Cartapip®, ein Albinostamm von Ophiostoma piliferum, mit dem Grünen Fluoreszenzprotein (GFP) transformieren lassen. Transformierte Stämme der beiden Pilzarten wurden mit PCR und Southern Blot Analysen untersucht. Das GFP wurde in Sporen, Synnemata und Myzelien der transformierten Stämme exprimiert. Dies war auf künstlichen Medien ebenso wie auf Holz der Fall. Wachstum, Pigmentierung und Holzbesiedelung waren bei den transformierten Stämmen ähnlich wie bei den nichttransformierten; somit dürfte die Präsenz des gfpGens keine negativen Auswirkungen auf die Biologie der transformierten Stämme haben. Mit Hilfe der Fluoreszenz- und Konfokal-Mikroskopie konnten die GFP exprimierenden Pilze leicht von den Wildtyp-Stämmen und anderen Pilzarten auf Holz unterschieden werden. Dies war auch noch vier Monate nach der Inokulation der Fall. Die Ergebnisse zeigen, dass das GFP-System zur Beobachtung von Ophiostoma -Arten im Holz geeignet ist. [source]

Development of a real-time PCR-based method for detection of Xylophilus ampelinus

PLANT PATHOLOGY, Issue 1 2007
T. Dreo
A real-time PCR MGB-probe-based detection method specific to Xylophilus ampelinus, the cause of grapevine bacterial blight, was developed. Used in combination with the DNeasy plant mini kit, the sensitivity of X. ampelinus detection was approximately 100 cells from tissue extracts, surpassing the sensitivity of an existing nested PCR method at least tenfold. In field samples a high correlation was observed between real-time PCR cycle threshold (Ct) values obtained and X. ampelinus isolation on artificial media. Isolation was successful from samples with Ct values below 25. Lower concentrations of X. ampelinus, with Ct values up to 36, could also be reliably detected in real-time PCR. The newly developed method offers a reliable and sensitive test for X. ampelinus, suitable as a screening test, complementary to isolation on media or other methods, and could also be used for fast and specific identification of isolated colonies and for relative quantification of X. ampelinus bacteria. [source]