Bi‐parental vs. cooperative breeding in a passerine: fitness‐maximizing strategies of males in response to risk of extra‐pair paternity?

In socially monogamous species, males that risk cuckoldry more than others might gain inclusive fitness by yielding paternity to relatives. We tested this prediction in the Tibetan ground tit Pseudopodoces humilis , an unusual facultative cooperative breeder wherein most helpers (87% males) join a mated pair shortly before clutch completion. Extra-pair paternity among bi-parental broods occurred less often (26% of broods, 9% of young) compared with cooperative broods (68%, 25%). In the former, most extra-pair sires (88%) were pair breeders unrelated to the cuckolded males, whereas in the latter, sires (87%) were mainly helpers related to the dominant males. Brood productivity did not differ between the bi-parental and cooperative breeders, but helpers' partitioning over group paternity reduced the realized reproductive success of helped males. After taking inclusive fitness into account, however, there was no difference in success of dominant males between the two social systems. One possible explanation for the differences in the rates of cuckoldry in the two systems was body size, because pair-bond males in bi-parental situations were significantly larger than those in cooperative ones. We propose two alternative strategies for males to maximize fitness: breed as a pair if large to avoid cuckoldry from helpers, or breed cooperatively if small but compromise some paternity to relatives. Our results provide an unusual route to the incidence of cooperative groups, based on constraints imposed by low competitive ability of breeding males rather than some external ecological or demographic factors.     

Product/Service‐Systems for a Circular Economy: The Route to Decoupling Economic Growth from Resource Consumption?

Product/service‐systems (PSS) that focus on selling service and performance instead of products are often mentioned as means to realize a circular economy (CE), in which economic growth is decoupled from resource consumption. However, a PSS is no implicit guarantee for a CE, and CE strategies do not necessarily lead to decoupling economic growth from resource consumption in absolute terms. Absolute resource decoupling only occurs when the resource use declines, irrespective of the growth rate of the economic driver. In this forum paper, we propose a two‐step framework that aims to support analyses of PSS and their potential to lead to absolute resource decoupling. In the first step, we present four PSS enablers of relative resource reduction that qualify as CE strategies. In the second step, three subsequent requirements need to be met, in order to successfully achieve absolute resource decoupling. Conditions and limitations for this accomplishment are discussed. Danish textile cases are used to exemplify the framework elements and its application. We expect that the framework will challenge the debate on the necessary conditions for CE strategies to ensure absolute resource decoupling.     

‘Idealized’ State 4 and State 3 in Mitochondria vs. Rest and Work in Skeletal Muscle

A computer model of oxidative phosphorylation (OXPHOS) in skeletal muscle is used to compare state 3, intermediate state and state 4 in mitochondria with rest and work in skeletal muscle. ‘Idealized’ state 4 and 3 in relation to various ‘experimental’ states 4 and 3 are defined. Theoretical simulations show, in accordance with experimental data, that oxygen consumption (V’O₂), ADP and P_i are higher, while ATP/ADP and Δp are lower in rest than in state 4, because of the presence of basal ATP consuming reactions in the former. It is postulated that moderate and intensive work in skeletal muscle is very different from state 3 in isolated mitochondria. V’O₂, ATP/ADP, Δp and the control of ATP usage over V’O₂ are much higher, while ADP and Pi are much lower in the former. The slope of the phenomenological V’O₂-ADP relationship is much steeper during the rest-work transition than during the state 4-state 3 transition. The work state in intact muscle is much more similar to intermediate state than to state 3 in isolated mitochondria in terms of ADP, ATP/ADP, Δp and metabolic control pattern, but not in terms of V’O₂. The huge differences between intact muscle and isolated mitochondria are proposed to be caused by the presence of the each-step activation (ESA) mechanism of the regulation of OXPHOS in intact skeletal muscle. Generally, the present study suggests that isolated mitochondria (at least in the absence of Ca²⁺) cannot serve as a good model of OXPHOS regulation in intact skeletal muscle.     

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

Symbiont‐bearing and non‐symbiotic marine bivalves were used as model organisms to establish biosignatures for the detection of distinctive symbioses in ancient bivalves. For this purpose, the isotopic composition of lipids (δ¹³C) and bulk organic shell matrix (δ¹³C, δ³⁴S, δ¹⁵N) from shells of several thiotrophic, phototrophic, or non‐symbiotic bivalves were compared (phototrophic: Fragum fragum, Fragum unedo, Tridacna maxima; thiotrophic: Codakia tigerina, Fimbria fimbriata, Anodontia sp.; non‐symbiotic: Tapes dorsatus, Vasticardium vertebratum, Scutarcopagia sp.). ?¹³C values of bulk organic shell matrices, most likely representing mainly original shell protein/chitin biomass, were depleted in thio‐ and phototrophic bivalves compared to non‐symbiotic bivalves. As the bulk organic shell matrix also showed a major depletion of δ¹⁵N (down to –2.2 ‰) for thiotrophic bivalves, combined δ¹³C and δ¹⁵N values are useful to differentiate between thio‐, phototrophic, and non‐symbiotic lifestyles. However, the use of these isotopic signatures for the study of ancient bivalves is limited by the preservation of the bulk organic shell matrix in fossils. Substantial alteration was clearly shown by detailed microscopic analyses of fossil (late Pleistocene) T. maxima and Trachycardium lacunosum shell, demonstrating a severe loss of quantity and quality of bulk organic shell matrix with time. Likewise, the composition and δ¹³C‐values of lipids from empty shells indicated that a large part of these compounds derived from prokaryotic decomposers. The use of lipids from ancient shells for the reconstruction of the bivalve's life style therefore appears to be restricted.     

Models for truth‐telling in physician‐patient encounters: What can we learn from Yoruba concept of Ooto?

Empirical studies have now established that many patients make clinical decisions based on models other than Anglo American model of truth‐telling and patient autonomy. Some scholars also add that current medical ethics frameworks and recent proposals for enhancing communication in health professional‐patient relationship have not adequately accommodated these models. In certain clinical contexts where health professional and patients are motivated by significant cultural and religious values, these current frameworks cannot prevent communication breakdown, which can, in turn, jeopardize patient care, cause undue distress to a patient in certain clinical contexts or negatively impact his/her relationship with the community. These empirical studies have now recommended that additional frameworks developed around other models of truth‐telling; and which take very seriously significant value‐differences which sometimes exist between health professional and patients, as well as patient's cultural/religious values or relational capacities, must be developed. This paper contributes towards the development of one. Specifically, this study proposes a framework for truth‐telling developed around African model of truth‐telling by drawing insights from the communitarian concept of oot?? amongst the Yoruba people of south west Nigeria. I am optimistic that if this model is incorporated into current medical ethics codes and curricula, it will significantly enhance health professional‐patient communication.     

What Should Be Held Steady in a Steady‐State Economy?: Interpreting Daly's Definition at the National Level

Within this article, I investigate a number of the conceptual issues that arise when attempting to translate Herman Daly's definition of a steady‐state economy (SSE) into a set of national biophysical indicators. Although Daly's definition gives a high‐level view of what would be held steady in an SSE, it also leaves many questions unanswered. How should stocks and flows be aggregated? What is the role of international trade? How should nonrenewable resources be treated? And where does natural capital fit in? To help answer these questions, I relate Daly's definition to key concepts and terminology from material and energy flow accounting. I explore topics such as aggregation, international trade, the relevance of throughput, and hidden flows. I conclude that a set of biophysical accounts for an SSE should include three types of indicators (stocks, flows, and scale), track how stocks and flows are changing over a 5‐ to 10‐year period, use aggregated data that measure the quantity of resource use (rather than its quality), measure both total and nonrenewable resource use, adopt a consumption‐based approach, include hidden flows, and exclude indicators that measure characteristics of the stock of natural capital (with the notable exception of indicators that measure the regenerative and assimilative capacities of ecosystems).     

Spontaneous succession in Central‐European man‐made habitats: What information can be used in restoration practice?

Abstract. The results of previous studies concerning spontaneous vegetation succession in various man‐made or disturbed habitats in Central Europe are discussed in relation to restoration ecology. An attempt is made to answer the main questions which are important to restoration programs. These concern the rate and direction of succession; participation of target species and communities, woody species, ruderals and aliens; arresting or diverting succession; changes in species diversity; variability of successional pathways and the role of abiotic environmental conditions. The great potential for using successional theory in restoration programs is emphasized.     

What is the proximate cause for size‐dependent ecophysiological differences in vascular epiphytes?

Size-related variation in physiological parameters as diverse as photosynthetic capacity, abscisic acid relationships or the relative water deficit at stomatal closure have been reported for a large number of vascular epiphytes, but the proximate mechanism behind these observations has not been identified. We test four possible reasons for size-related changes in photosynthetic capacity, leaf-N content and specific leaf area: (i) plant size itself, (ii) plant age or developmental stage, (iii) previous nutrition, or (iv) previous water regime. A suite of study species and approaches were used: a 'natural experiment' with the orchid Polystachya foliosa; an experimental field study with another orchid, Dimerandra emarginata; and a study under controlled conditions with the tank bromeliad, Vriesea sanguinolenta. Neither size, age nor differences in water supply caused differences in leaf N and photosynthetic capacity, while low supply of nutrients yielded, and high supply with nutrients completely removed, size-related trends. The observed size-related trends are thus a consequence of in situ differences in nutrient acquisition. Arguably, the improved nutrient status of larger plants under natural conditions results from larger tanks, holding moisture for increasingly longer intervals, which allows longer periods of decomposition of detritus and of nutrient uptake.     

From fever to immunity: A new role for IGFBP‐6?

Fever is a fundamental response to infection and a hallmark of inflammatory disease, which has been conserved and shaped through millions of years of natural selection. Although fever is able to stimulate both innate and adaptive immune responses, the very nature of all the molecular thermosensors, the timing and the detailed mechanisms translating a physical trigger into a fundamental biological response are incompletely understood. Here we discuss the consequence of hyperthermic stress in dendritic cells (DCs), and how the sole physical input is sensed as an alert stimulus triggering a complex transition in a very narrow temporal window. Importantly, we review recent findings demonstrating the significant and specific changes discovered in gene expression and in the metabolic phenotype associated with hyperthermia in DCs. Furthermore, we discuss the results that support a model based on a thermally induced autocrine signalling, which rewires and sets a metabolism checkpoint linked to immune activation of dendritic cells. Importantly, in this context, we highlight the novel regulatory functions discovered for IGFBP‐6 protein: induction of chemotaxis; capacity to increase oxidative burst and degranulation of neutrophils, ability to induce metabolic changes in DCs. Finally, we discuss the role of IGFBP‐6 in autoimmune disease and how novel mechanistic insights could lead to exploit thermal stress‐related mechanisms in the context of cancer therapy.     

WHISCY: What information does surface conservation yield? Application to data‐driven docking

Protein-protein interactions play a key role in biological processes. Identifying the interacting residues is a first step toward understanding these interactions at a structural level. In this study, the interface prediction program WHISCY is presented. It combines surface conservation and structural information to predict protein-protein interfaces. The accuracy of the predictions is more than three times higher than a random prediction. These predictions have been combined with another interface prediction program, ProMate [Neuvirth et al. J Mol Biol 2004;338:181-199], resulting in an even more accurate predictor. The usefulness of the predictions was tested using the data-driven docking program HADDOCK [Dominguez et al. J Am Chem Soc 2003;125:1731-1737] in an unbound docking experiment, with the goal of generating as many near-native structures as possible. Unrefined rigid body docking solutions within 10 A ligand RMSD from the true structure were generated for 22 out of 25 docked complexes. For 18 complexes, more than 100 of the 8000 generated models were correct. Our results demonstrates the potential of using interface predictions to drive protein-protein docking.     

Split‐root systems applied to the study of the legume‐rhizobial symbiosis: What have we learned?

Split‐root system (SRS) approaches allow the differential treatment of separate and independent root systems, while sharing a common aerial part. As such, SRS is a useful tool for the discrimination of systemic (shoot origin) versus local (root/nodule origin) regulation mechanisms. This type of approach is particularly useful when studying the complex regulatory mechanisms governing the symbiosis established between legumes and Rhizobium bacteria. The current work provides an overview of the main insights gained from the application of SRS approaches to understand how nodule number (nodulation autoregulation) and nitrogen fixation are controlled both under non‐stressful conditions and in response to a variety of stresses. Nodule number appears to be mainly controlled at the systemic level through a signal which is produced by nodule/root tissue, translocated to the shoot, and transmitted back to the root system, involving shoot Leu‐rich repeat receptor‐like kinases. In contrast, both local and systemic mechanisms have been shown to operate for the regulation of nitrogenase activity in nodules. Under drought and heavy metal stress, the regulation is mostly local, whereas the application of exogenous nitrogen seems to exert a regulation of nitrogen fixation both at the local and systemic levels.     

Tobacco use vs. helminths in Congo basin hunter-gatherers: self-medication in humans?

We tested a novel hypothesis that recreational use of neurotoxic plants helps defend against parasites. Specifically, we investigated the relationship between smoking and helminthiasis among the Aka, a remote population of Central African foragers who are avid tobacco smokers, suffer high rates of helminthiasis, and have little-to-no access to commercial anthelmintics. Two hundred and six healthy Aka men provided saliva and stool samples. Saliva samples were assayed for cotinine, a nicotine metabolite; a subsample was genotyped for the CYP2A6 enzyme, which metabolizes nicotine. Stool samples were assayed for intestinal helminth eggs as an index of worm burden. After 1 year, a subsample of participants was located and provided additional saliva and stool samples. We found (1) an exceptionally high prevalence of tobacco use, (2) a significant negative correlation between cotinine (a nicotine metabolite) and worm burden, (3) that treating helminths with albendazole, a commercial anthelmintic, reduced cotinine concentration two weeks later, compared to placebo controls, (4) among treated participants, higher cotinine concentrations in year 1 predicted less reinfection by year 2, and (5) younger and older participants with slow nicotine-metabolizing CYP2A6 alleles had lower worm burdens compared to those with extensive metabolizing alleles. These results provide the first evidence of a link between helminthiasis and smoking. They also suggest that, in populations where intestinal helminths are endemic, tobacco use might protect against helminth infection and reduce worm burden among infected individuals, and that individuals modulate nicotine exposure in response to infection. The results thus support the hypothesis that substance use helps defend against parasites.