Investment in immune function under chronic and acute immune challenge in an insect

In this paper we investigate the relationship between the chronic burden of mid‐gut parasites (eugregarine trophozooites) and the effect of an acute haemolymph challenge (a nylon insert) on two important insect immune effector systems (phenol oxidase (PO) and the encapsulation response) in a field‐population of damselflies. PO levels in the haemolymph, and the magnitude of the encapsulation response were maintained, regardless of chronic and subsequent acute experimental immune challenges. The maintenance of these effector systems is therefore probably an important life‐history requirement in these damselflies. Investment in mid‐gut PO levels was significantly negatively related to the animal's chronic parasite burden after an acute experimental challenge in the haemolymph, suggesting that maintaining PO levels across two physiological compartments (haemolymph and mid‐gut) is costly. The results suggest that the immune effector system activity in different physiological compartments in an insect's body is affected by chronic parasite burdens in the face of the demands imposed by an acute immune insult.     

Introduction of a functional P element into the germ-line of Drosophila hawaiiensis

When a plasmid carrying a P-transposable element (derived from Drosophila melanogaster) is injected into young embryos of D. hawaiiensis, the P-element sequence from the plasmid transposes into the germ-line chromosomes. The introduction of this P element into D. hawaiiensis provides an opportunity to study the behavior of the transposable element in a novel context. Germ-line transposition and numerical increase of the P elements are readily detected in D. hawaiiensis. Thus these aspects of P-element function do not require chromosomal or cytoplasmic properties that are unique to D. melanogaster. Since D. hawaiiensis is among those Drosophila that are most distantly related to D. melanogaster, these results suggest that P-element-mediated transformation may function in many species.     

Tracking leatherback turtles (Dermochelys coriacea) during consecutive inter-nesting intervals: Further support for direct transmitter attachment

Over recent years there have been substantial efforts to record and interpret the post-nesting movements of leatherback turtles (Dermochelys coriacea) breeding in tropical regions. Less well documented are the movements undertaken by individual turtles during the breeding season itself, or more specifically between sequential nesting events. Such movements are of interest for two reasons: (1) gravid female leatherbacks may range extensively into the territorial waters and nesting beaches of neighbouring countries, raising questions for conservationists and population ecologists; and (2) the magnitude of movements themselves help elucidate underlying reproductive strategies (e.g. whether to rest near to the nesting or forage extensively). Here, satellite relay data loggers are used (SRDLs) to detail the movements and behaviour of two female leatherback turtles throughout three consecutive inter-nesting intervals in the Commonwealth of Dominica, West Indies. Both near-shore residence and extensive inter-nesting movements were recorded, contrasting previous studies, with movements away from the nesting beach increasing towards the end of the nesting season. Using this behavioural study as a backdrop, the suitability of attaching satellite transmitters directly to the carapace was additionally explored as an alternative approach to conventional harness deployments. Specifically, the principal aims were to (1) gather empirical data on speed of travel and (2) assess dive performance (aerobic dive limit) to enable comparisons with turtles previously fitted with harnesses elsewhere in the Caribbean (n = 6 turtles; Grenada, WI). This produced mixed results with animals bearing directly attached transmitters travelling significantly faster (55.21 km day^− 1; SD 6.68) than harnessed individuals (39.80 km day^− 1; SD 6.19); whilst no discernable difference in dive performance could be found between the two groups of study animals.     

Single-enzyme kinetics with fluorogenic substrates: lessons learnt and future directions

Single-molecule fluorescence techniques have developed into powerful tools for studying the kinetics of biological reactions at the single-molecule level. Using fluorogenic substrates, enzymatic reactions can be observed in real-time with single-turnover resolution. The turnover sequence contains all kinetic information, giving access to reaction substeps and dynamic processes such as fluctuations in the reaction rate. Despite their clearly proven potential, the accuracy of current measurements is limited by the availability of substrates with 1:1 stoichiometry and the signal-to-noise ratio of the measurement. In this review we summarize the state-of-the-art and discuss these limitations using experiments performed with α-chymotrypsin as an example. We are further providing an overview of recent efforts aimed at the improvement of fluorogenic substrates and the development of new detection schemes. These detection schemes utilize nanophotonic structures such as zero mode waveguides or nanoantennas. Nanophotonic approaches reduce the size of the effective detection volume and are a powerful strategy to increase the signal-to-noise ratio. We believe that a combination of improved substrates and novel detection schemes will pave the way for performing accurate single-enzyme experiments in biologically relevant conditions.     

Genome diversity at the serA-linked capsule locus in Escherichia coli

Individual isolates of Escherichia coli synthesize one of more than 70 chemically distinct polysaccharides which form the capsule. In this article we review the genetics of capsule production in E. coli and highlight what this is beginning to reveal in terms of the genetic basis of the structural diversity of polysaccharides. The serA-linked capsule locus can take three different allelic forms. Two of these are associated with capsule genes and are themselves internally variant, whilst the third form has not so far been implicated in capsule biogenesis. Thus the serA-linked region of the E. coli genome is strikingly polymorphic.     

Lessons from the Ebola Outbreak: Action Items for Emerging Infectious Disease Preparedness and Response

EcoHealth - As the Ebola outbreak in West Africa wanes, it is time for the international scientific community to reflect on how to improve the detection of and coordinated response to future...     

Late Glacial and Early Holocene human demographic responses to climatic and environmental change in Atlantic Iberia

Successive generations of hunter–gatherers of the Late Glacial and Early Holocene in Iberia had to contend with rapidly changing environments and climatic conditions. This constrained their economic resources and capacity for demographic growth. The Atlantic façade of Iberia was occupied throughout these times and witnessed very significant environmental transformations. Archaeology offers a perspective on how past human population ecologies changed in response to this scenario. Archaeological radiocarbon data are used here to reconstruct demographics of the region over the long term. We introduce various quantitative methods that allow us to develop palaeodemographic and spatio-temporal models of population growth and density, and compare our results to independent records of palaeoenvironmental and palaeodietary change, and growth rates derived from skeletal data. Our results demonstrate that late glacial population growth was stifled by the Younger Dryas stadial, but populations grew in size and density during the Early to Middle Holocene transition. This growth was fuelled in part by an increased dependence on marine and estuarine food sources, demonstrating how the environment was linked to demographic change via the resource base, and ultimately the carrying capacity of the environment.This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.