Hydrolytic extracellular enzyme activity in heterotrophic biofilms from two contrasting streams

SUMMARY. 1. Extracellular hydrolytic enzyme activities and cell densities were monitored during undisrupted biofilm formation on pristine surfaces in two contrasting river sites in North Wales: an oligotrophic mountain stream (Nant Waen) and a mildly eutrophic river (River Clywedog).
2. Bacterial densities generally increased at both sites over a 33-day monitoring period. Densities in the eutrophic site were approximately 14 times greater than in the mountain stream.
3. Using fluorescent substrate analogues, biofilms from Nant Waen produced low, variable xylosidase and β-glucosidase activities. Biofilms from the more eutrophic River Clywedog produced higher xylosidase and β-glucosidase activities and detectable endopeptidase, though these activities also fluctuated during the colonization period.
4. Unlike the other activities measured, esterase activities in the River Clywedog were correlated with cell densities ( P <0.05). When extracellular esterase activities per cell were calculated, the oligotrophic biofilm was found to contain about twice as much extracellular esterase activity as the more eutrophic River Clywedog biofilm.     

Dehydration in an Australian rockpool chironomid larva, (Paraborniella tonnoiri)

The effects of drought on the survival of the larvae of Paraborniella tonnoiri are examined. The rate and extent of water loss are determined and the temperature tolerance of aestivating and active larvae are compared.     

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.