Behavioural response of workers to repeated intergroup encounters in the harvester ant Messor barbarus

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.The evolution of cooperation in animal societies is often associated with the evolution of hostility towards members of other groups. It is usually predicted that groups under attack from outsiders should respond by becoming more cohesive or cooperative. However, the responses of individuals to real or simulated intergroup encounters vary widely, for reasons that are poorly understood. We tested how groups of workers of the harvester ant, Messor barbarus, responded to exposure to members of a different colony versus members of their own colony, and how previous exposure to an intruder affected the intensity of the within-group response. We found that workers increased in activity and had more contact with one another immediately following exposure to an ant from a different colony, but also showed a similar behavioural response to presentations involving an ant from their own colony. However, exposure to an intruder from a different colony resulted in much stronger behavioural responses to a second intruder, encountered shortly afterwards. Our results are consistent with studies of social vertebrates which suggest that exposure to intruders results in increased social cohesion. Our results also show that exposure to an intruder primes group members to respond more strongly to future intrusions. Our findings highlight a disconnect between the assumptions of theoretical models which study the effect of intergroup conflict on social evolution over many generations, and the short-term behavioural responses that are the usual focus of studies of intergroup conflict in insects and vertebrates.Natural Environment Research Council (NERC

A contribution to understanding the complex nature of peisleyite

The type specimen of peisleyite has been reinvestigated by a combination of scanning electron microscopy, electron probe microanalysis (EPMA) and synchrotron powder X-ray diffraction. Morphological investigation showed that mats of peisleyite crystals, individually <3 μm across, are intergrown with wavellite veinlets to form the white cryptocrystalline material that is typical of 'peisleyite'. New EPMA data (mean of 12 analyses) gave the empirical formula of peisleyite as (Na_(1.69)Ca_(0.18))_(Σ1.87)(Al_(9.04)Fe_(0.03))_(Σ9.07)[(P_(6.28)S_(1.38)Si_(0.25))O_4]_(Σ7.91)(OH)_(6.66)·27.73H_2O, or ideally Na_2Al_9[(P,S)O_4]_8(OH)_6·28H_2O. The associated wavellite was found to be F-rich. Synchrotron powder data were indexed and refined and gave the following unit cell: P1, a = 9.280(19), b = 11.976(19), c = 13.250(18) Å, α = 91.3(1), β = 75.6(1), γ = 67.67(1)º, V = 1308(5) Å3 and Z = 4. These data are significantly different to those reported in the original description of peisleyite

What is the role of mitochondrial dysfunction in skin photoaging?

Skin ageing is a complex process involving both internal and external factors, which leads to a progressive loss of cutaneous function and structure. Solar radiation is the primary environmental factor implicated in the development of skin ageing and the term photoageing describes the distinct clinical, histological and structural features of chronically sun-exposed skin. The changes that accompany photoageing are undesirable for aesthetic reasons and can compromise the skin and make it more susceptible to a number of dermatological disorders. As a result, skin ageing is a now topic that is of growing interest and concern to the general population, illustrated by the increased demand for effective interventions that can prevent or ameliorate the clinical changes associated with aged skin. In this viewpoint essay we explore the role that mitochondria play in the process of skin photoageing. There is continuing evidence supporting the proposal that mitochondria dysfunction and oxidative stress are important contributing factors in the development of skin photoageing. Further skin-directed mitochondrial research is warranted to fully understand the impact of mitochondrial status and function in skin health. A greater understanding of the ageing process and the regulatory mechanisms involved could lead to the development of novel preventative andtherapeutic interventions for skin ageing

Instrumentation for fluorescence lifetime measurement using photon counting

We describe the evolution of HORIBA Jobin Yvon IBH Ltd, and its time-correlated single-photon counting (TCSPC) products, from university research beginnings through to its present place as a market leader in fluorescence lifetime spectroscopy. The company philosophy is to ensure leading-edge research capabilities continue to be incorporated into instruments in order to meet the needs of the diverse range of customer applications, which span a multitude of scientific and engineering disciplines. We illustrate some of the range of activities of a scientific instrument company in meeting this goal and highlight by way of an exemplar the performance of the versatile DeltaFlex instrument in measuring fluorescence lifetimes. This includes resolving fluorescence lifetimes down to 5 ps, as frequently observed in energy transfer, nanoparticle metrology with sub-nanometre resolution and measuring a fluorescence lifetime in as little as 60 μs for the study of transient species and kinetics

New high-pressure phase of HfTiO4 and ZrTiO4 ceramics

We studied the high-pressure effects on the crystalline structure of monoclinic HfTiO4 and ZrTiO4. We found that the compressibility of these ceramics is highly non-isotropic, being the b-axis the most compressible one. In addition, the a-axis is found to have a small and negative compressibility. At 2.7 GPa (10.7 GPa) we discovered the onset of an structural phase transition in HfTiO4 (ZrTiO4), coexisting the low- and high-pressure phases in a broad pressure range. The new high-pressure phase has a monoclinic structure which involves an increase in the Ti-O coordination and a collapse of the cell volume. The equation of state for the low-pressure phase is also determined.Comment: 16 pages, 5 figures, 26 references, Article in Pres

Defence against the intergenerational cost of reproduction in males: oxidative shielding of the germline.

This is the final version. Available from Wiley via the DOI in this record. Reproduction is expected to carry an oxidative cost, yet in many species breeders appear to sustain lower levels of oxidative damage compared to non-breeders. This paradox may be explained by considering the intergenerational costs of reproduction. Specifically, a reduction in oxidative damage upon transitioning to a reproductive state may represent a pre-emptive shielding strategy to protect the next generation from intergenerational oxidative damage (IOD) - known as the oxidative shielding hypothesis. Males may be particularly likely to transmit IOD, because sperm are highly susceptible to oxidative damage. Yet, the possibility of male-mediated IOD remains largely uninvestigated. Here, we present a conceptual and methodological framework to assess intergenerational costs of reproduction and oxidative shielding of the germline in males. We discuss variance in reproductive costs and expected payoffs of oxidative shielding according to species' life histories, and the expected impact on offspring fitness. Oxidative shielding presents an opportunity to incorporate intergenerational effects into the advancing field of life-history evolution.Natural Environment Research Council (NERC)Natural Environment Research Council (NERC