Free-living Panagrellus Redivivus Research Articles

Serratia sp., an endophyte of Mimosa pudica nodules with nematicidal, antifungal activity and growth-promoting characteristics.

In the present study, the nematicidal activity of an isolated strain of Mimosa pudica nodules was evaluated against the Nacobbus aberrans (J2) phytonymatodes with a mortality of 88.8%, while against the gastrointestinal nematode Haemonchus contortus (L3) and free-living Panagrellus redivivus was 100%. The ability to inhibit the growth of phytopathogenic fungi Fusarium sp., and Alternaria solani, as well as the oomycete Phytophthora capsici, this antifungal activity may be related to the ability to produce cellulases, siderophores and chitinases by this bacterial strain. Another important finding was the detection of plant growth promoter characteristics, such as auxin production and phosphate solubilization. The strain identified by sequences of the 16S and rpoB genes as Serratia sp. is genetically related to Serratia marcescens and Serratia nematodiphila. The promoter activity of plant growth, antifungal and nematicide of the Serratia sp. strain makes it an alternative for the biocontrol of fungi and nematodes that affect both the livestock and agricultural sectors, likewise, candidate as a growth-promoting bacterium.

In vitro proteolysis of nematode FMRFamide-like peptides (FLPs) by preparations from a free-living nematode (Panagrellus redivivus) and two plant-parasitic nematodes (Heteroderaglycines and Meloidogyne incognita)

Proteolytic activities in extracts from three nematodes, the plant parasites Heterodera glycines and Meloidogyne incognita, and the free-living Panagrellus redivivus, were surveyed for substrate preferences using a battery of seven FRET-modified peptide substrates, all derived from members of the large FMRF-amide like peptide (FLP) family in nematodes. Overall protease activity in P. redivivus was four- to fivefold greater than in either of the parasites, a result that might reflect developmental differences. Digestion of the M. incognita FLP KHEFVRFa (substrate Abz-KHEFVRF-Y(3-NO2)a) by M. incognita extract was sevenfold greater than with H. glycines extract and twofold greater than P. redivivus, suggesting species-specific preferences. Additional species differences were revealed upon screening 12 different protease inhibitors. Two substrates were used in the screen, Abz-KHEFVRF-Y(3-NO2)a and Abz-KPSFVRF-Y(3-NO2)a), which was digested equally by all three species. The effects of various inhibitor, substrate and extract source combinations on substrate digestion suggest that M. incognita differs significantly from P. redivivus and H. glycines in its complement of cysteine proteases, particularly cathepsin L-type protease.

Observations on the Trapping of Nematodes by Dactylaria Scaphoides Using Optical, Transmission and Scanning-Electron-Microscopic Techniques

SUMMARY The host-predator relationships between two nematodes, the freeliving Panagrellus redivivus, the myceliophagous Aphelenchus avenae, and the predaceous hyphomycete Dactylaria scaphoides were investigated using light and scanning-electron microscopy of whole-mount preparations and transmission-electron microscopy of ultra-thin resin (Spurr) sections. The three-dimensional adhesive networks consistently trapped the nematodes under our experimental conditions. The reticulate traps were adhesive, but penetration was effected by appressoria produced on short hyphal branches from trapping hyphae. The infection process was very broad and produced a large infection bulb within the nematode from which infection hyphae developed. Chemical lysis appeared to function in the penetration process, with little evidence of mechanical pressure being involved. The matrix which bounds the infection process and the infection bulb of D. scaphoides is compared with the bounding structures in D. brochopaga and D. candida (constricting-ring and adhesive-knob-forming trappers respectively). The present study was undertaken to examine selected aspects of the host-predator relationship existing between the reticulate-network-forming hyphomycete Dactylaria scaphoides Peach and its nematode prey by optical and transmission and scanning-electron-microscope techniques. These involved both whole-mount preparations and ultra-thin sections of resin-embedded specimens. The predaceous hyphomycete D. scaphoides produces three-dimensional adhesive networks. Peach (1952) described this fungus and stated it was capable of capturing and causing the death of nematodes belonging to various genera. Once entangled in the network, the worm eventually becomes quiescent due to penetration by means of an appressorium, subsequent formation of an infection bulb and, from the latter, production of infection hyphae which finally digest the contents of the animal.