- Tytuł:
-
Toksyczne metabolity wytwarzane przez pasożytniczy grzyb Conidiobolus coronatus
Toxic metabolites produced by parasitic fungus Conidiobolus coronatus - Autorzy:
- Wieloch, W.
- Powiązania:
- https://bibliotekanauki.pl/articles/2144082.pdf
- Data publikacji:
- 2007
- Wydawca:
- Polskie Towarzystwo Parazytologiczne
- Tematy:
-
metabolity toksyczne
grzyby pasozytnicze
parazytologia
mikotoksyny
Entomophthorales
Conidiobolus coronatus
toksycznosc
Galleria mellonella - Opis:
- Naturally occurring entomopathogens are important regulatory factors of insect populations. Among them are entomopathogenic fungi. The invasion of insects by parasitic fungi occurs through penetration of the host integument. Death of the host is a result of tissue destruction, exhaustion of nutrients or the production of toxins. Conidiobolus coronatus (Entomophthorales) is a saprophytic soil fungus that kills insects by releasing toxins inside insect body, before the invasion of host's organs and tissues by fungal hyphae. It is pathogenic to a number of insects and could be relatively easily propagated in laboratory conditions. The fungus is an interesting object to study and might be the source of new insecticidal substances as well. The main aim of the study was isolation and characterisation of active compounds produced by C. coronatus. In experimental surveys of interactions between insects and entomopathogenic fungi it is important to establish simple and reliable method of quantification of fungal pathogenicity towards insects, and to chose right insect target as well. Four methods were tested on two species — Galleria mellonella and Dendrolimus pini: (1) immersing larvae in conidial suspension; (2) deposition the conidia on the cuticle; (3) injection into hemocoel, and (4) exposure to fungal colony. Exposition of G. mellonella larvae to fungal colony was chosen, as the best method to quantify C. coronatus pathogenicity, reflecting possible contact of insects with fungal spores in nature. D. pini larvae were not chosen to further experiments. Dark colour of their body disables the estimation of fungal infection progress. The fungus produces an array of enzymes regarded as necessary in efficient penetration of insect cuticle: proteases, chitinases and lipases, which degrade the components of the integument. The activity of those enzymes was measured in mycelial homogenates and in post incubation media. In homogenates the activity of elastase, N−acetylglucosaminidase (NAGase) and lipase was denoted. The homogenate had no chymotripsin and chitinase activity. In the incubation media the activity of five examined enzymes was present. Elastase and NAGase activities were much higher than those of three other enzymes. The long term observation of four colonies in laboratory conditions from one transfer to another revealed differences in the ability to kill G. mellonella larvae. The colonies reduced pathogenicity during several transfers and then relapsed into higher level of pathogenicity again. The fluctuations were more or less regular and appeared through two−year duration of the experiment. The nature of this fluctuation is unknown and no similar phenomenon was observed elsewhere. To elicit the possible background of instability of fungal cultures towards G. mellonella, a genetic analysis was performed on colonies derived from primary conidia, containing several dozen of nuclei, and microconidia, which are formed on the surface of primary conidia and containing a maximum several nuclei. Both analyses: DNA Fingerprinting and Amplified Fragments Length Polymorphism (AFLP) revealed that colonies isolated from primary conidia or microconidia differ in the genetic profile. The genetic differences reflect the differences in the pathogenicity trait. Genetic analysis of colonies derived from microconidia proved that nuclei differ genetically, which means that C. coronatus mycelium is heterokaryotic. A chromatographic separation of fungal homogenate proteins did not succeed. Better possibility gave the separation of proteins released by fungus to minimal medium. By two step high pressure liquid chromatography: size exclusion and ion exchange four proteins were separated to homogeneity, according to SDS−PAGE. Two of them in the size 14.5 kDa and 36 kDa were moderately pathogenic to G. mellonella larvae in the dose of 1µg per larva (20% and 10% of pathogenicity, respectively), and exhibited no enzymatic activity. Third protein was a 33−34 kDa elastase with no pathogenic effect. The last protein in the size 36−37 kDa was pathogenic to the larvae (20%) and exhibited elastolytic and chitinolytic activities. Further experiments will elicit the mode of actions on cell cultures of those four isolated proteins.
- Źródło:
-
Wiadomości Parazytologiczne; 2007, 53, 4; 355-357
0043-5163 - Pojawia się w:
- Wiadomości Parazytologiczne
- Dostawca treści:
- Biblioteka Nauki
Artykuł