Oxidising activity in root extracts from plants inoculated with virus or buffer that interferes with ELISA when using the substrate 3,3', 5,5'-tetramethylbenzidine

In indirect ELISA using protein A-horseradish peroxidase (HRP) as enzyme conjugate and 3,3′, 5,5′-tetramethylbenzidine (TMB) as substrate, extracts of roots of all cucumber, Chenopodium quinoa and Petunia hybrida plants previously inoculated with virus or buffer produced A₄₅₀ values up to seven-fold greater than those for comparable shoots or for extracts of roots from undisturbed, uninoculated plants, irrespective of the virus antiserum used for detection. This effect was also produced in tests in which no HRP conjugate was used, indicating that root extracts from virus-infected or physically injured plants, but not healthy uninjured plants, contain high levels of a factor able to oxidise TMB. The HRP conjugate/TMB substrate version of ELISA is therefore not reliable for detecting viruses in root extracts of herbaceous plants. In contrast, non-specific reactions were not obtained with root extracts, and viruses were reliably detected, when protein A-alkaline phosphatase was used as conjugate and p-nitrophenyl phosphate as substrate.     

Xylem Sap Composition in Apple Trees: Effect of the graft union

This paper records studies on the xylem sap from above and belowthe graft unions of apple trees with M·9, M·7and MM.104 rootstocks. The dry weight of solutes in sap fromabove the unions of the M·9 trees was between 30 and50 per cent lower than in sap from below, while the volume ofsap exuded was not reduced. The graft unions of the M·7and MM·104 trees had no significant effect on the xylemsap. These results are discussed in relation to the dwarfing effectsof rootstocks and interstocks.     

Phylogeography of the last surviving populations of Rhodian and Anatolian fallow deer (Dama dama dama L., 1758)

The European fallow deer ( Dama dama dama ) is one of the most widespread cervids, and its distribution has been heavily affected by man. At present, only one wild autochthonous population is reputed to survive in Anatolia, but its census size is dramatically decreasing. This means that a significant portion of the ancestral genetic diversity of this taxon is seriously threatened. In the present study, a portion of the mitochondrial DNA (D-loop) in 37 D. d. dama specimens from three Mediterranean sites, Turkey, the island of Rhodes (Greece), and the Italian Peninsula, and seven individuals of the Persian fallow deer, Dama dama mesopotamica , was sequenced, and the results from the data analysis are interpreted in light of current archaeozoological and biogeographical knowledge. We conclude that: (1) D. d. mesopotamica is strongly differentiated from D. d. dama , confirming the results of previous genetic studies and (2) the Rhodian populations of D. d. dama , founded by humans in Neolithic times, possess a set of mitochondrial lineages, found in no other study populations. The persistence of these haplotypes is particularly significant because human-mediated processes (e.g. domestication) usually result in genetic depletion and erosion of an ancestral genetic pool. In the case of the Rhodes' population of fallow deer, we hypothesize that, during the foundation of this population, humans unknowingly preserved a remarkable portion of the original genetic diversity of the source population(s).  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 835–844.     

Responses of male Mediterranean fruit flies, Ceratitis capitata, to trimediure in a wind tunnel of novel design

ABSTRACT. The responses of male Ceratitis capitata (Wiedemann) (Diptera; Tephritidae) to trimediure were investigated in a wind tunnel of novel design with disposable plastic walls. Trimediure was presented to the flies either in the form of a discrete 'plume' or uniformly dispersed in the air passing through the tunnel. The flies showed an increase in flight activity in response to the two forms of stimulation and performed a zig-zag anemotactic flight in response to the plume, reminiscent of the behaviour of moths responding to a sex pheromone. They performed a straight, upwind, anemotactic response to the uniformly dispersed odour. The design of wind tunnel used in these tests was found to have several advantages: air flow and turbulence can be easily varied and the plastic walls can be changed to eliminate contamination problems.     

Effect of strain-specific hypersensitive resistance on spatial patterns of virus spread

Spatial patterns of spread were compared between strains of Bean yellow mosaic virus (BYMV) that differ in causing systemic necrotic (hypersensitive) or non‐necrotic symptoms in narrow‐leafed lupin (Lupinus angustifolius). Both types of BYMV were spread naturally by aphids from adjacent infected pasture into a large lupin block (‘natural spread site’), or from clover plants introduced as virus sources into two field experiments with lupin. Cumulative spatial data for plants with disease symptoms from a range of times in the growing period were assessed using Spatial Analysis by Distance IndicEs (SADIE). At the‘natural spread site’, with non‐necrotic BYMV, the extent of clustering of plants with symptoms increased gradually over time, while with necrotic BYMV there was less clustering and no increase over time. In both experiments, for the type of BYMV that was introduced into a plot, there was a gradual increase in clustering, but with this being greater with non‐necrotic BYMV. In the second experiment, there was also significant clustering of plants with symptoms of non‐necrotic BYMV in plots without introduced non‐necrotic foci but not for necrotic BYMV in plots without introduced necrotic foci. When clustering data for plants with newly recorded symptoms was tested for spatial association between successive assessment dates, association was positive for both BYMV types though stronger for the non‐necrotic type, declining as the temporal lag increased. Generally, association was strongest for assessments 2–3 wk apart, corresponding approximately to the period for BYMV to move systemically in plants and for obvious symptoms to appear in shoot tips. Contour maps for local association between dates showed that the strongest spatial associations were from coincidence of infection gaps rather than infection patches. The combination of information from clustering and association analysis showed that spread of non‐necrotic BYMV is less diffuse, with considerably more localised infection surrounding the infection sources. This work demonstrates how spatial virus spread can be diminished when hypersensitive (necrotic) resistance is deployed, and the limitations associated with employing hypersensitivity that is strain specific.     

Microsatellite DNA polymorphism confirms reproductive isolation and reveals differences in population genetic structure of cryptic pipistrelle bat species

Previous studies have indicated that the common European pipistrelle bat ( Pipistrellus pipistrellus ) comprises two cryptic species, P. pipistrellus and Pipistrellus pygmaeus , which differ in echolocation call frequency and mitochondrial DNA sequence. However, levels of divergence based on nuclear markers have not been examined, and hence the potential for male-mediated gene flow between the species cannot be discounted. Moreover, little is known about population structure and migration patterns in either species. Here, we describe the use of microsatellites to investigate nuclear DNA differentiation between, and the pattern of population genetic structure within, the two cryptic pipistrelle species. In total, 1300 individuals from 82 maternity colonies were sampled across the British Isles and Continental Europe. We show, using multivariate analyses, that colonies of the same species are generally genetically more similar to each other than to those from the other species regardless of geographical location. Our findings support the hypothesis that the species are reproductively isolated. Significant patterns of genetic isolation by distance were identified in both species, indicating that mating may occur before any long-distance autumnal migration. The presence of a sea channel does not confer higher levels of genetic differentiation among colonies over and above distance alone in either species. Differences in genetic population structure were identified between the species, with P. pipistrellus showing a wider range of levels of genetic differentiation among colonies and a stronger relationship between genetic and geographical distance than P. pygmaeus . Differences in dispersal, mating behaviour, colony size and/or postglacial colonization patterns could contribute to the differences observed.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 539–550.