FMRFamide-like peptides in root knot nematodes and their potential role in nematode physiology.

FMRFamide-like peptides (FLPs) are a diverse group of neuropeptides that are expressed abundantly in nematodes. They exert potent physiological effects on locomotory, feeding and reproductive musculature and also act as neuromodulators. However, little is known about the specific expression patterns and functions of individual peptides. The current study employed rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) to characterize flp genes from infective juveniles of the root knot nematodes, Meloidogyne incognita and Meloidogyne minor. The peptides identified from these transcripts are sequelogs of FLPs from the free-living nematode, Caenorhabditis elegans; the genes have therefore been designated as Mi-flp-1, Mi-flp-7, Mi-flp-12, Mm-flp-12 and Mi-flp-14. Mi-flp-1 encodes five FLPs with the common C-terminal moiety, NFLRFamide. Mi-flp-7 encodes two copies of APLDRSALVRFamide and APLDRAAMVRFamide and one copy of APFDRSSMVRFamide. Mi-flp-12 and Mm-flp-12 encode the novel peptide KNNKFEFIRFamide (a longer version of RNKFEFIRFamide found in C. elegans). Mi-flp-14 encodes a single copy of KHEYLRFamide (commonly known as AF2 and regarded as the most abundant nematode FLP), and a single copy of the novel peptide KHEFVRFamide. These FLPs share a high degree of conservation between Meloidogyne species and nematodes from other clades, including those of humans and animals, perhaps suggesting a common neurophysiological role which may be exploited by novel drugs. FLP immunoreactivity was observed for the first time in Meloidogyne, in the circumpharyngeal nerve ring, pharyngeal nerves and ventral nerve cord. Additionally, in situ hybridization revealed Mi-flp-12 expression in an RIR-like neuron and Mi-flp-14 expression in SMB-like neurons, respectively. These localizations imply physiological roles for FLP-12 and FLP-14 peptides, including locomotion and sensory perception.

Management of the potato cyst nematode (Globodera pallida) with bio-fumigants/stimulants.

Field trials evaluated the effect of four plant-based bio-fumigants/stimulants on population levels of G. pallida and the resulting potato yields and quality. Three formulations contained seaweed biostimulants (Algifol, Nutridip and Metastim) and one bio-fumigant containing mustard and chilli pepper extracts (Dazitol). These were compared with the fumigant nematicide Nemathorin and untreated control plots. The effect of G. pallida on growing potato crops was assessed by recording haulm characteristics which indicated that the nematicide treatment gave most protection. Levels of PCN juveniles and migratory nematodes were assessed during the trial. Plots treated with Nemathorin and Dazitol had fewest PCN, whilst the highest number of migratory nematodes occurred in fallow plots. Sixteen weeks after planting the nematicide treatment produced highest yield and tuber numbers. Dazitol treatment produced a lower yield but the largest tubers.

Management of root knot nematodes in turfgrass using mustard formulations and biostimulants.

The control of nematodes in turfgrass poses particular problems for turf managers. Due to the nature of this specialized "crop" system, many of the options available in agriculture and horticulture are impractical and the range of available chemical controls limited. This is particularly highlighted by the withdrawal of fenamiphos, one of the most widely used nematicides in the turfgrass industry. Mustard products are known to release allyl isothiocyanate, a potent nematicide. Laboratory based trials have shown mustard formulations can release enough of this chemical to significantly reduce numbers of root knot nematodes in pot trials using sand based soils. During 2005, trialling at a number of golf courses assessed the efficacy of mustard as a practical alternative to fenamiphos. During heavy nematode infestations, turf grass is exposed to high levels of stress resulting from direct nematode feeding damage as well as the usual environmental stresses imposed by low cutting and heavy wear and tear during play. Stress relief using biostimulants has proven useful in helping maintaining turf cover in these situations and can be applied as part of the normal turf management programme.

Neuromuscular function in plant parasitic nematodes: a target for novel control strategies?

Over the last decade the need for new strategies and compounds to control parasitic helminths has become increasingly urgent. The neuromuscular systems of these worms have been espoused as potential sources of target molecules for new drugs which may address this need. One facet of helminth neuromuscular biology which has garnered considerable research interest is that of neuropeptidergic neurotransmission, particularly regarding parasites of humans and animals, as well as free-living nematode model species. This research interest has been piqued by the fact that neuropeptides have been demonstrated to be fundamentally important to nematode biology and thus may be of utility in this search for new drug targets. This review focuses on the neuropeptide biology of plant parasitic nematodes, a subject which has been comparatively neglected despite the fact that the search for alternative control measures also extends to these economically important parasites. We focus on the FMRFamide-like peptide (FLP) neuropeptides and the complexity and distribution of this peptide family in plant parasitic nematodes. Possible roles for FLPs in plant parasitic nematode behaviour, as elucidated by a combination of molecular imaging techniques and RNA interference (RNAi), are discussed. We propose that disruption of FLP neurosignalling in plant parasitic nematodes represents a novel form of pest control and speculate as to how this may be achieved.

FMRFamide-related peptides in potato cyst nematodes.

This study presents data demonstrating the presence of FMRFamide-related peptides (FaRPs) in potato cyst nematodes (PCN). Five transcripts of FaRP encoding genes, designated gpflp-1 to gpflp-5, were characterised using RACE. In terms of ORFs, gpflp-1 was 444 base pairs (bp) long and coded for four copies of the FaRP, PF3 (KSAYMRFamide) whilst gpflp-2 was 309 bp long and encoded one copy of the peptide, KNKFEFIRFamide. gpflp-3 (420 bp) Encoded two copies of KHEYLRFamide (AF2) and the genes gpflp-4 and gpflp-5 encoded a total of 11 FaRPs, most of which are novel to PCN. FMRFamide-related peptide (FaRP)-like immunoreactivity was observed in both PCN species, Globodera pallida and Globodera rostochiensis, using an antiserum raised against the invertebrate peptide, FMRFamide. Immunopositive neurones were found throughout the central nervous system in the ventral and dorsal nerve cords and the circumpharyngeal and perianal nerve rings. Reactive neurones were also present peripherally, innervating the highly muscular pharynx with a nerve net and ring-like structures. Positive immunostaining was also observed in neurones running toward the stylet protractor muscles and/or the anterior sensory apparatus. This study implicates a role for FaRPs in feeding, host penetration and sensory function of PCN. This is the first study to characterise FaRP encoding genes from a plant-parasitic nematode using a targeted PCR based RACE approach and further underlines the importance and diversity of this neuropeptide group in the phylum Nematoda.

Three divergent rDNA clusters predate the species divergence in Quercus petraea (Matt.) Liebl. and Quercus robur L.

Quercus petraea and Quercus robur are two closely related oak species that frequently hybridize. We sequenced 70 clones containing the 5.8S and ITS2 regions of ribosomal DNA (rDNA) from these two species and did not detect a species-specific difference. Surprisingly, three divergent (up to 12.6%) rDNA families were identified in both species, indicating that they predate the speciation event. Despite a large between-rDNA-families divergence, rDNA sequences were very similar within families, suggesting ongoing concerted evolution. Expression analysis, relative-rate tests, and mutation spectrum analyses indicated that only a single rDNA family is functional. We propose that past hybridization events, combined with nucleolar dominance, were the evolutionary processes underlying the contemporary rDNA variability in Q. petraea and Q. robur.

The rDNA Internal Transcribed Spacer Region as a Taxonomic Marker for Nematodes.

The ITS region from a wide taxonomic range of nematodes, including secernentean and adenophorean taxa, and free-living, entomopathogenic, and plant-parasitic species, was evaluated as a taxonomic marker. Size of the amplified product aided in the initial determination of group membership, and also suggested groups that may require taxonomic reevaluation. Congeneric species often displayed identically sized ITS regions, but genera such as Pratylenchus and Tylenchorhynchus had species with large differences in size. ITS heterogeneity in individuals and populations was identified in several nematode taxa. PCR-RFLP of ITS1 is advocated as a method of taxonomic analysis in genera such as Helicotylenchus that contain numerous species with few diagnostic morphological characteristics.

The effects of perceived control on the paired-associate learning of elderly persons.

Forty-five elderly subjects performed a modified paired-associate learning task under two conditions designed to enhance their perception of control. Subjects in enhanced control conditions chose their own response items ("choice" subjects) or were allowed to manually control response interval duration ("self-paced"). Yoked controls learned the same items selected by choice subjects, or experienced pacing conditions under which they were allowed comparable amounts of response time. The design was an incomplete 2 x 3 x 6 factorial with two types of item selection (choice vs. force), three types of pacing (self-paced, yoked item-by-item, yoke by trial median time), and six trials. There was no "choice" group in the "item yoked" pacing condition. As predicted, subjects experiencing either or both of the control-enhancing conditions performed better than yoked controls. Experiencing both item choice and self-pacing did not result in performance which was significantly better than that of subjects experiencing only one or the other. Results are discussed in light of previous work with young persons, and recommendations are offered to researchers.