Association patterns and kinship in female reindeer (Rangifer tarandus) during rut

Non-random association of females has been reported in many social species, with kinship being the main mechanism in shaping these associations. Understanding the patterns of association during rut is particularly important in polygynous animals, as this may have implications for inbreeding vulnerability and genetic structuring of populations. However, these patterns are highly dynamic and may be influenced by the population sex ratio and male age structure. We examined females' association in reindeer (Rangifer tarandus), a highly polygynous ungulate, to determine whether genetically related females associate more often than non-kin during rut and whether this association was influenced by the aforementioned factors. During three rutting seasons the male age structure and the sex ratio of the herd was manipulated: two extremely female biased sex ratios, one with only adult males and one with only young males, whereas the third being closer to a more even sex ratio and male age structure. We found that genetic relatedness influenced female association in the mixed male age group, but not in the adult and young male age groups. Highly related females (relatedness ??0.5) associated more closely than unrelated females. Further, period of the rut as well as male age structure and sex ratio had a significant effect on female association. Our study suggests that the female reindeer association during rut is not only influenced by preference for kin but also by male?Cmale competition and male age as well.     

Reproductive strategy of two deep-sea scalpellid barnacles (Crustacea: Cirripedia: Thoracica) associated with decapods and pycnogonids and the first description of a penis in scalpellid dwarf males

We investigated the sexual system in two pedunculate barnacles of the family Scalpellidae. Both inhabit deep water and are attached to mobile arthropod hosts. Verum brachiumcancri was attached to the majid crab Rochinia hertwigi, and Weltnerium nymphocola to the pycnogonidan sea spider Boreonymphon rubrum. Both barnacles have separate sexes and females almost always carry two dwarf males that are almost fully embedded in a pair of symmetrically situated receptacles inside the rim of the mantle cavity. The dwarf males of V. brachiumcancri have a complex penile structure extending into the female mantle cavity. This is the first time a copulatory structure has been described in detail for a dwarf male of a scalpellid barnacle. Both species lack free nauplii and their larvae are released as cyprids; the brood size is small. This is probably an adaptation for settling close to the parent population. We compare reproductive strategies among scalpellids and suggest that the present males are highly specialized and that the females are allocating resources to few offspring.     

Human exonuclease 1 (EXO1) activity characterization and its function on flap structures

Human exonuclease 1 (EXO1) is involved in multiple DNA metabolism processes, including DNA repair and replication. Most of the fundamental roles of EXO1 have been described in yeast. Here, we report a biochemical characterization of human full-length EXO1. Prior to assay EXO1 on different DNA flap structures, we determined factors essential for the thermodynamic stability of EXO1. We show that enzymatic activity and stability of EXO1 on DNA is modulated by temperature. By characterization of EXO1 flap activity using various DNA flap substrates, we show that EXO1 has a strong capacity for degrading double stranded DNA and has a modest endonuclease or 5′ flap activity. Furthermore, we report novel mechanistic insights into the processing of flap structures, showing that EXO1 preferentially cleaves one nucleotide inwards in a double stranded region of a forked and nicked DNA flap substrates, suggesting a possible role of EXO1 in strand displacement.     

Effect of Energy Metabolism on Protein Motility in the Bacterial Outer Membrane

We demonstrate the energy dependence of the motion of a porin, the λ-receptor, in the outer membrane of living Escherichia coli by single molecule investigations. By poisoning the bacteria with arsenate and azide, the bacterial energy metabolism was stopped. The motility of individual λ-receptors significantly and rapidly decreased upon energy depletion. We suggest two different causes for the ceased motility upon comprised energy metabolism: One possible cause is that the cell uses energy to actively wiggle its proteins, this energy being one order-of-magnitude larger than thermal energy. Another possible cause is an induced change in the connection between the λ-receptor and the membrane structure, for instance by a stiffening of part of the membrane structure. Treatment of the cells with ampicillin, which directly targets the bacterial cell wall by inhibiting cross-linking of the peptidoglycan layer, had an effect similar to energy depletion and the motility of the λ-receptor significantly decreased. Since the λ-receptor is closely linked to the peptidoglycan layer, we propose that λ-receptor motility is directly coupled to the constant and dynamic energy-consuming reconstruction of the peptidoglycan layer. The result of this motion could be to facilitate transport of maltose-dextrins through the porin.     

A study on variability of quantitative sensory testing in healthy participants and painful temporomandibular disorder patients

Objectives: Quantitative sensory testing has mainly used thresholds to evaluate somatosensory sensitivity so far. The variability of different measures from session to session has also been investigated, but the variability of the single individual measures of a threshold or subject-based reports has not been considered. This study aimed to investigate the potential value of threshold variability in one session as a measure of internal consistency in somatosensory function.

Methods: The standardized quantitative sensory testing battery developed by the German Research Network on Neuropathic Pain was performed bilaterally over the infraorbital, mental, and hand regions in 70 healthy and 22 temporomandibular disorder pain participants. Somatosensory variability was investigated by calculating the Coefficient of Variation of three to five repeated measures in one threshold determination. The influences of side, gender, site, age, and presence of pain on the somatosensory variability were evaluated.

Results: In the healthy participants, somatosensory variability was region dependent: hand?>?mental and/or infraorbital for CDT, WDT, HPT, MDT-N, MPT-Y, MPT-N, WUR, and MPS (p?≤?0.043), infraorbital?>?hand for VDT (p?=?0.001), mental?>?infraorbital for HPT and WUR (p?≤?0.001); and age dependent for WDT, TSL, CPT, HPT, MDT-Y, MDT-N, MPT-N, and WUR (p?≤?0.017). Gender and side had no main effect on variability (p?≥?0.136). The pain patients presented higher variability compared with healthy participants for TSL, MDT-N, MPT-Y, WUR, and PPT (p?≤?0.033).

Discussion: The somatosensory variability along with the threshold would be a more complete method to investigate the somatosensory disorders and underlying pain mechanisms. The correlation between pain duration and somatosensory variability should be studied further with different pain conditions.     

ESCRT & Co

Components of the ESCRT (endosomal sorting complex required for transport) machinery mediate endosomal sorting of ubiquitinated membrane proteins. They are key regulators of biological processes important for cell growth and survival, such as growth‐factor‐mediated signalling and cytokinesis. In addition, enveloped viruses, such as HIV‐1, hijack and utilize the ESCRTs for budding during virus release and infection. Obviously, the ESCRT‐facilitated pathways require tight regulation, which is partly mediated by a group of interacting proteins, for which our knowledge is growing. In this review we discuss the different ESCRT‐modulating proteins and how they influence ESCRT‐dependent processes, for example, by acting as positive or negative regulators or by providing temporal and spatial control. A number of the interactors influence the classical ESCRT‐mediated process of endosomal cargo sorting, for example, by modulating the interaction between ubiquitinated cargo and the ESCRTs. Certain accessory proteins have been implicated in regulating the activity or steady‐state expression levels of the ESCRT components, whereas other interactors control the cellular localization of the ESCRTs, for example, by inducing shuttling between cytosol and nucleus or endosomes. In conclusion, the discovery of novel interactors has and will extend our knowledge of the biological roles of ESCRTs.     

Temporal and geographical variations in grass pollen seasons in areas of west0ern Europe: an analysis of season dates at sites of the European pollen information system

Geographical and temporal variations in the start dates of grass pollen seasons are described for selected sites of the European Pollen Information Service. Daily average grass pollen counts are derived from Network sites in Finland, the Netherlands, Denmark, United Kingdom, Austria, Italy and Spain, giving a broad longitudinal transect over Western Europe. The study is part of a larger project that also examines annual and regional variations in the severity, timing of the peak and duration of the grass pollen seasons. For several sites, data are available for over twenty years enabling long term trends to be discerned. The analyses show notable contrasts in the progression of the seasons annually with differing lag times occurring between southern and northern sites in various years depending on the weather conditions. The patterns identified provide some insight into geographical differences and temporal trends in the incidence of pollinosis. The paper discusses the main difficulties involved in this type of analysis and notes possibilities for using data from the European Pollen Information service to construct pan European predictive models for pollen seasons. This revised version was published online in June 2006 with corrections to the Cover Date.