Increased nitrous oxide emissions from a drained organic forest soil after exclusion of ectomycorrhizal mycelia

The aim of this study was to determine how roots and their ectomycorrhizal symbionts affect the fluxes of nitrous oxide (N₂O) from nutrient-rich drained organic forest soils. Specifically, the relative impacts of roots and mycorrhizal mycelia on N₂O fluxes were investigated using two different trenching treatments, excluding (a) roots or (b) roots and mycorrhizal mycelia, from the soil. N₂O fluxes were measured at the soil surface, for 1 year before and 2.5 years after trenching, within the two trenching treatments and on untreated controls. While the exclusion of roots alone did not affect N₂O emissions, the simultaneous exclusion of roots and mycorrhizal mycelia doubled N₂O emissions, compared to the control plots. Two probable explanations for the increased fluxes were identified: (1) a decreased uptake of nitrogen (N) from the soil, through the mycorrhizal fungi, which increased N availability for the N₂O-producing microorganisms, and (2) a decreased uptake of water from the soil, through the mycorrhiza, which increased the soil water content and thus the N₂O emissions from denitrification. If the trenching reduced any potential stimulation of N cycling, through rhizodeposition, this mechanism did not outweigh the effects of a discontinued mycorrhizal N and/or water uptake on N₂O fluxes. The results of the study emphasise the importance of ectomycorrhiza in regulating N₂O emissions from forested organic soils.     

Regulation of the host response to bacterial lipopolysaccharides

Bacterial endotoxins or lipopolysaccharides (LPS) are unique glycolipids present in the outer cell membrane of all gram-negative bacteria. It is now generally recognized that LPS is of primary importance in initiating the pathophysiological changes that often accompany gram-negative bacillary infections in humans including hypotensive shock, disseminated intravascular coagulation, and metabolic abnormalities. Although the biochemical mechanisms of these changes are not well understood, increasing emphasis has been placed on defining the biochemical response of the macrophage (M phi) to LPS. In this paper we describe two M phi-derived factors induced by LPS that may be important in the expression of endotoxic activity in the host. These are a procoagulant activity, which is present on the cell membrane of LPS-treated rabbit liver M phi and acts by directly activating coagulation factor X, and a factor released into the supernatant by LPS-treated peritoneal exudate M phi, which suppresses steroidogenesis in explanted adrenocortical cells. The potential role of the M phi in regulating the binding of LPS to high-density lipoproteins through the induction of acute phase proteins is also considered.     

An ancient look at UCP1

Brown adipose tissue serves as a thermogenic organ in placental mammals to defend body temperature in the cold by nonshivering thermogenesis. The thermogenic function of brown adipose tissue is enabled by several specialised features on the organ as well as on the cellular level, including dense sympathetic innervation and vascularisation, high lipolytic capacity and mitochondrial density and the unique expression of uncoupling protein 1 (UCP1). This mitochondrial carrier protein is inserted into the inner mitochondrial membrane and stimulates maximum mitochondrial respiration by dissipating proton-motive force as heat. Studies in knockout mice have clearly demonstrated that UCP1 is essential for nonshivering thermogenesis in brown adipose tissue. For a long time it had been presumed that brown adipose tissue and UCP1 emerged in placental mammals providing them with a unique advantage to survive in the cold. Our subsequent discoveries of UCP1 orthologues in ectotherm vertebrates and marsupials clearly refute this presumption. We can now initiate comparative studies on the structure-function relationships in UCP1 orthologues from different vertebrates to elucidate when during vertebrate evolution UCP1 gained the biochemical properties required for nonshivering thermogenesis.     

Mouse models of rhinovirus-induced disease and exacerbation of allergic airway inflammation

Rhinoviruses cause serious morbidity and mortality as the major etiological agents of asthma exacerbations and the common cold. A major obstacle to understanding disease pathogenesis and to the development of effective therapies has been the lack of a small-animal model for rhinovirus infection. Of the 100 known rhinovirus serotypes, 90% (the major group) use human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor and do not bind mouse ICAM-1; the remaining 10% (the minor group) use a member of the low-density lipoprotein receptor family and can bind the mouse counterpart. Here we describe three novel mouse models of rhinovirus infection: minor-group rhinovirus infection of BALB/c mice, major-group rhinovirus infection of transgenic BALB/c mice expressing a mouse-human ICAM-1 chimera and rhinovirus-induced exacerbation of allergic airway inflammation. These models have features similar to those observed in rhinovirus infection in humans, including augmentation of allergic airway inflammation, and will be useful in the development of future therapies for colds and asthma exacerbations.     

Zoning has little impact on the seasonal diel activity and distribution patterns of wild boar (Sus scrofa) in an UNESCO Biosphere Reserve

Understanding the spatio‐temporal distribution of ungulates is important for effective wildlife management, particularly for economically and ecologically important species such as wild boar (Sus scrofa). Wild boars are generally considered to exhibit substantial behavioral flexibility, but it is unclear how their behavior varies across different conservation management regimes and levels of human pressure. To analyze if and how wild boars adjust their space use or their temporal niche, we surveyed wild boars across the core and buffer zones (collectively referred to as the conservation zone) and the transition zone of a biosphere reserve. These zones represent low and high levels of human pressure, respectively. Specifically, we employed a network of 53 camera traps distributed in the Schaalsee UNESCO Biosphere Reserve over a 14‐month period (19,062 trap nights) and estimated circadian activity patterns, diel activity levels, and occupancy of wild boars in both zones. To account for differences in environmental conditions and day length, we estimated these parameters separately for seven 2‐month periods. Our results showed that the wild boars were primarily nocturnal, with diurnal activity occurring dominantly during the summer months. The diel activity patterns in the two zones were very similar overall, although the wild boars were slightly less active in the transition zone than in the conservation zone. Diel activity levels also varied seasonally, ranging from 7.5 to 11.0 h day⁻¹, and scaled positively with the length of the night (R ² = 0.66–0.67). Seasonal occupancy estimates were exceptionally high (point estimates ranged from 0.65 to 0.99) and similar across zones, suggesting that the wild boars used most of the biosphere reserve. Overall, this result suggests that different conservation management regimes (in this case, the zoning of a biosphere reserve) have little impact on wild boar behavior. This finding is relevant for wildlife management in protected areas where possibly high wild boar densities could interfere with conservation goals within these areas and those of agricultural land use in their vicinity.     

Experimental parasite infection reveals costs and benefits of paternal effects

Forces shaping an individual's phenotype are complex and include transgenerational effects. Despite low investment into reproduction, a father's environment and phenotype can shape its offspring's phenotype. Whether and when such paternal effects are adaptive, however, remains elusive. Using three‐spined sticklebacks in controlled infection experiments, we show that sperm deficiencies in exposed males compared to their unexposed brothers functionally translated into reduced reproductive success in sperm competition trials. In non‐competitive fertilisations, offspring of exposed males suffered significant costs of reduced hatching success and survival but they reached a higher body condition than their counterparts from unexposed fathers after experimental infection. Interestingly, those benefits of paternal infection did not result from increased resistance but from increased tolerance to the parasite. Altogether, these results demonstrate that parasite resistance and tolerance are shaped by processes involving both genetic and non‐genetic inheritance and suggest a context‐dependent adaptive value of paternal effects.     

Timing and probability of ovulation in relation to sex skin swelling in wild West African chimpanzees, Pan troglodytes verus

Females of many catharrine primates show a periodic and often pronounced swelling of the perineum, the functional significance of which is unclear. Several hypotheses that exist to explain the function of this conspicuous trait are based on assumptions about the temporal relation between the period of maximum swelling and ovulation, and remain largely untested. We examined this relation in free-living chimpanzees of the Ta? National Park, Côte d'Ivoire, and assessed the reliability of perineal swelling as an indicator of ovulation in this species. We used noninvasive urinary progestogen analysis of female reproductive status, together with observational data on swelling characteristics, to determine the variability of timing of ovulation within the maximum swelling phase in 36 cycles from 12 females. The period of maximum swelling was highly variable, lasting from 6 to 18 days. Although ovulation was virtually restricted to the second half of the period of maximum tumescence, its timing varied considerably in relation to both the onset and the end of the maximum tumescence phase. Probability of ovulation, however, was not random, but peaked on day 7 after the onset of the maximum swelling phase, and was almost 60% between days 7 and 9. Thus, in wild chimpanzees perineal swelling indicates the probability of ovulation, but does not provide sufficient information to deduce its exact timing. Given the temporal variability of ovulation relative to the last day of maximum tumescence, field workers should try to include hormonal analysis if information on timing of ovulation is required for interpretation of observational data. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

Never Out of the Woods: Onset of Events in Long QT Syndrome Late in Life Provoked by Atrial Arrhythmias

The assessment of risk in the asymptomatic patient with long QT syndrome can often be a challenging task, particularly when the available evidence is limited to relatively small retrospective registries, not to mention the need to consider the effect of individual patient factors which are often difficult to quantitate. We describe the relatively uncommon case of a man with a long-standing diagnosis of Long QT 2 syndrome who suffered his first cardiac event in his late 60''s, likely precipitated by the development of paroxysmal atrial tachycardia. A brief review of the available literature on risk assessment in adults with genetically confirmed long QT syndrome who have remained asymptomatic late into adulthood will follow the case.