Novel microsatellite loci identified from the Australian eastern small‐eyed snake (Elapidae: Rhinocephalus nigrescens) and cross species amplification in the related genus Suta

A total of 15 microsatellite primers pairs were developed for the Australian small‐eyed snake Rhinoplocephalus nigrescens. Five primers were used to screen 93 individuals of R. nigrescens and were also tested against eight species of the closely related genus Suta. Allelic diversity in R. nigrescens was high in three loci (12–27) and there was high heterozygosity (0.58–0.82). Observed heterozygosity did not deviate from Hardy–Weinberg expectations for the five loci tested. These primers will be useful in studies of population genetics and mating systems of small‐eyed snakes and related species.     

Carbon balance assessment of a Belgian winter wheat crop (Triticum aestivum L.)

The carbon balance of a winter wheat crop in Lonzée, Belgium, was assessed from measurements carried out at different spatial and temporal scales between November 2004 and August 2005. From eddy covariance measurements, the net ecosystem exchange was found to be ?0.63 kg C m^?2 and resulted from the difference between gross primary productivity (GPP) (?1.58 kg C m^?2) and total ecosystem respiration (TER) (0.95 kg C m^?2). The impact of the u_* threshold value on these fluxes was assessed and found to be very small. GPP assessment was partially validated by comparison with an estimation scaled up from leaf scale assimilation measurements. Soil respiration (SR), extrapolated from chamber measurements, was 0.52 kg C m^?2. Net primary productivity, assessed from crop sampling, was ?0.83 kg C m^?2. By combining these fluxes, the autotrophic and heterotrophic components of respiration were deduced. Autotrophic respiration dominated both TER and SR. The evolution of these fluxes was analysed in relation to wheat development.     

Microsatellite loci for Bombus spp.

We report the details and characteristics of a total of 44 novel microsatelllite loci for Bombus spp. Most of them are highly polymorphic in Bombus terrestris, and a high degree of polymorphism is also found where these primers have been tested in 10 other bumblebee species. These markers will therefore be useful for the genetic study of this group.     

Host activity and wasp experience affect parasitoid wasp foraging behaviour and oviposition on nematode‐infected larvae of the forestry pest Hylobius abietis

1. Entomopathogenic nematodes (EPN) are currently being used as introduced biological control agents against the larvae of the native European forestry pest Hylobius abietis L. which develop under the bark of stumps and roots of newly dead conifer trees. 2. The potential for resource competition between gregarious ectoparasitoid Bracon hylobii Ratz and EPN by recording oviposition and related behaviours of B. hylobii females on EPN‐infected H. abietis larvae was investigated. Wasps did not parasitise EPN‐infected host larvae that were dead when presented, but naÏve and experienced wasps parasitised live EPN‐infected hosts. NaÏve wasps parasitised live EPN‐infected hosts significantly less frequently than healthy hosts only when the infected larvae were close to death (i.e. died during 24‐h trial). Parasitism by experienced wasps was unaffected by host infection. 3. Wasp probing and oviposition were positively associated with the amount of host movement. Preventing H. abietis larvae from chewing on bark significantly reduced parasitism by naÏve, but not experienced wasps. 4. The number of eggs per clutch was not affected by bark chewing or EPN‐infection of H. abietis larvae. 5. NaÏve and experienced B. hylobii parasitised two abnormal hosts (larvae of coleopteran Rhagium bifasciatum Fabricius and lepidopteran Galleria mellonella L.), both of which moved and chewed on bark during trials. 6. It was concluded that B. hylobii can use vibrational cues generated by host movement and feeding to locate hosts at short range and accepts unsuitable (EPN‐infected or abnormal) hosts as long as these create such cues. The implications for competition between B. hylobii and EPN and possible ways of minimising it when applying EPN are discussed.     

Drought and Oxidative Load in the Leaves of C3 Plants: a Predominant Role for Photorespiration?

Although active oxygen species are produced at high rates inboth the chloroplasts and peroxisomes of the leaves of C₃ plants,most attention has focused on the potentially damaging consequencesof enhanced chloroplastic production in stress conditions suchas drought. This article attempts to provide quantitative estimatesof the relative contributions of the chloroplast electron transportchain and the glycolate oxidase reaction to the oxidative loadplaced on the photosynthetic leaf cell. Rates of photorespiratoryH₂O₂ production were obtained from photosynthetic and photorespiratoryflux rates, derived from steady-state leaf gas exchange measurementsat varying irradiance and ambient CO₂. Assuming a 10 % allocationof photosynthetic electron flow to the Mehler reaction, photorespiratoryH₂O₂ production would account for about 70 % of total H₂O₂ formedat all irradiances measured. When chloroplastic CO₂ concentrationrates are decreased, photorespiration becomes even more predominantin H₂O₂ generation. At the increased flux through photorespirationobserved at lower ambient CO₂, the Mehler reaction would haveto account for more than 35 % of the total photosynthetic electronflow in order to match the rate of peroxisomal H₂O₂ production.The potential signalling role of H₂O₂ produced in the peroxisomesis emphasized, and it is demonstrated that photorespiratoryH₂O₂ can perturb the redox states of leaf antioxidant pools.We discuss the interactions between oxidants, antioxidants andredox changes leading to modified gene expression, particularlyin relation to drought, and call attention to the potentialsignificance of photorespiratory H₂O₂ in signalling and acclimation.     

Use of additive models to represent trends in a barley field trial

Even when a field experiment has been designed with care, subsequent examination of the plot values may reveal additional unforeseen trends. In this paper we examine data from a barley pathology field trial and show that additive models provide a flexible representation of environmental trends, in one or two dimensions. Such models smooth out noise in the observed data, rather than fit an equation specified in advance. This approach tends to increase the precision of treatment comparisons relative to a classical analysis of variance. We recommend the use of residual plots to explore experimental data for underlying trends, and additive models to display these trends and estimate treatment effects.     

Synthesis of Acetylcholine in the Absence of Exogenous Choline

THE breakdown of acetyl-CoA during incubation with rat brain homogenate or sections of rat nervous tissue in the absence of choline has been reported by Kasa, Mann and Hebb¹. They found that the conversion of ¹⁴C-acetyl-CoA to ¹⁴C-acetate thus incubated was considerably depressed by 10^?4 eserine or 10^?5 M di-isopropylfluorophosphate (DFP) but further depressed by 10^?3 M DFP. Experiments in our laboratories lead us to offer an explanation for that part of the breakdown inhibited by eserine or low concentrations of DFP.     

Aerobic Metabolism of Brochothrix thermosphacta Growing on Meat Surfaces and in Laboratory Media

Acetoin and acetic, isobutyric and isovaleric acids are major end-products, and important components of the spoilage odours, of Brochothrix thermosphacta growing aerobically on meat surfaces or in tryptone-based medium containing glucose, ribose or glycerol. Acetoin and acetic acid are probably derived entirely from the carbohydrates and isobutyric and isovaleric acids from valine and leucine respectively. Glucose and pH are both important factors in controlling the relative amounts of end-products, low glucose and near neutral pH favouring fatty acid formation, high glucose and lower pH values favouring acetoin formation.