How a bottom‐dweller beats the canopy: inhibition of an aquatic weed (Potamogeton pectinatus) by macroalgae (Chara spp.)

1. Bottom‐dwelling charophytes have been observed to replace canopy‐forming pondweeds within a few years in de‐eutrophied shallow lakes. Competition for bicarbonate (HCO₃^?) may explain this shift in vegetation dominance but inhibition of pondweeds by Chara spp. through direct competition has not been shown experimentally. 2. We tested whether charophytes inhibited growth of fennel pondweed (Potamogeton pectinatus) in the absence of belowground competition by growing plants in pots in mesocosms following a replacement series experimental design. To further understand the role of bicarbonate, we studied main and interactive effects of Chara, light and bicarbonate on P. pectinatus growth in a laboratory study. 3. Early in the mesocosm experiment, high charophyte densities had a negative effect on P. pectinatus cover at a time when bicarbonate levels were low. However, bicarbonate levels eventually converged to low levels in all treatments. At final harvest, both species exhibited lower biomasses at higher densities of conspecific pots, indicating that ultimately intraspecific competition was limiting. In a laboratory study, Chara inhibited P. pectinatus the most under a combination of high light and high bicarbonate concentrations, suggesting that Chara may negatively affect P. pectinatus by acting as a general nutrient sink. 4. Our results suggest that Chara growth can reduce bicarbonate levels, delaying but not preventing a P. pectinatus growth pulse. Given the recorded inhibition under ample bicarbonate supply, Chara’s ability to act as nutrient sink may contribute to the decline of P. pectinatus under Chara recovery in shallow lakes.     

Impacts of Hurricane Frances on Florida scrub-oak ecosystem processes: defoliation, net CO2 exchange and interactions with elevated CO2

Hurricane disturbances have profound impacts on ecosystem structure and function, yet their effects on ecosystem CO₂ exchange have not been reported. In September 2004, our research site on a fire‐regenerated scrub‐oak ecosystem in central Florida was struck by Hurricane Frances with sustained winds of 113 km h⁻¹ and wind gusts as high as 152 km h⁻¹. We quantified the hurricane damage on this ecosystem resulting from defoliation: we measured net ecosystem CO₂ exchange, the damage and recovery of leaf area, and determined whether growth in elevated carbon dioxide concentration in the atmosphere (C_a) altered this disturbance. The hurricane decreased leaf area index (LAI) by 21%, which was equal to 60% of seasonal variation in canopy growth during the previous 3 years, but stem damage was negligible. The reduction in LAI led to a 22% decline in gross primary production (GPP) and a 25% decline in ecosystem respiration (R_e). The compensatory declines in GPP and R_e resulted in no significant change in net ecosystem production (NEP). Refoliation began within a month after the hurricane, although this period was out of phase with the regular foliation period, and recovered 20% of the defoliation loss within 2.5 months. Full recovery of LAI, ecosystem CO₂ assimilation, and ecosystem respiration did not occur until the next growing season. Plants exposed to elevated C_a did not sustain greater damage, nor did they recover faster than plants grown under ambient C_a. Thus, our results indicate that hurricanes capable of causing significant defoliation with negligible damage to stems have negligible effects on NEP under current or future CO₂‐enriched environment.     

THE ONGOING CHARITY OF ORGAN DONATION. CONTEMPORARY ENGLISH SUNNI FATWAS ON ORGAN DONATION AND BLOOD TRANSFUSION

Background: Empirical studies in Muslim communities on organ donation and blood transfusion show that Muslim counsellors play an important role in the decision process. Despite the emerging importance of online English Sunni fatwas, these fatwas on organ donation and blood transfusion have hardly been studied, thus creating a gap in our knowledge of contemporary Islamic views on the subject. Method: We analysed 70 English Sunni e‐fatwas and subjected them to an in‐depth text analysis in order to reveal the key concepts in the Islamic ethical framework regarding organ donation and blood transfusion. Results: All 70 fatwas allow for organ donation and blood transfusion. Autotransplantation is no problem at all if done for medical reasons. Allotransplantation, both from a living and a dead donor, appears to be possible though only in quite restricted ways. Xenotransplantation is less often mentioned but can be allowed in case of necessity. Transplantation in general is seen as an ongoing form of charity. Nearly half of the fatwas allowing blood transfusion do so without mentioning any restriction or problem whatsoever. The other half of the fatwas on transfusion contain the same conditional approval as found in the arguments pro organ transplantation. Conclusion: Our findings are very much in line with the international literature on the subject. We found two new elements: debates on the definition of the moment of death are hardly mentioned in the English Sunni fatwas and organ donation and blood transfusion are presented as an ongoing form of charity.     

Sibship reconstruction demonstrates the extremely low effective population size of striped bass Morone saxatilis in the Santee–Cooper system, South Carolina, USA

For organisms with great fecundity and high mortality in early life stages, such as shellfish or fishes, the need to match reproductive activity with environmental conditions conducive to spawning, fertilization, larval development and recruitment may result in extreme variance in reproductive success among individuals. The main objective of this study was to investigate evidence of large variance in the reproductive success of the striped bass Morone saxatilis in the Santee–Cooper system, South Carolina, USA. Seven microsatellite loci were analysed in 603 recruits representing three yearly cohorts from 1992 to 1994, and a group analysis was performed to identify full-sib families. Large variance in reproductive success was detected, with a few large, full-sib families contributing disproportionately to each of the cohorts. The severity of sweepstakes reproductive success varied among cohorts depending on environmentally imposed mortality. Estimations of the effective number of breeders in these long-lived fish ranged from 24 in 1992 to 44 in 1994. Furthermore, the estimated genetic effective population size ( N _e = 93) is approximately four orders of magnitude lower than estimates of adult census size ( N  =   362 000). Furthermore, the presence of large full-sib families indicates that striped bass engage in pair mating in the wild. Heterogeneity in genetic composition was also observed among cohorts, suggesting that genetically different adults contribute to different cohorts and that chance rather than fitness variation determines reproductive success.     

Meeting Review: Advances from the GPCR Retreat

In London, Ontario, the 8th Annual Joint meeting of the Great Lakes GPCR Retreat and the Club des Récepteurs à Sept Domaines Transmembranaires (now known simply as the GPCR Retreat) was held September 27–29, 2007. This meeting gathers together a core group of investigators from Michigan, Ontario, and Québec and has steadily increased its attendance in both the eastern (Europe) and western (USA, Canada) directions. The highlight this year was a sneak preview of the β₂AR crystal structure provided by Brian Kobilka, but as can be seen below, many other cutting edge talks were heard as well.     

G Protein-Coupled Receptors in and on the Cell Nucleus: A New Signaling Paradigm?

Signaling from internalizing and endosomal receptors has almost become a classic GPCR paradigm in the last several years. However, it has become clear in recent years that GPCRs also elicit signals when resident at other subcellular sites including the endoplasmic reticulum, Golgi apparatus, and the nucleus. In this review we discuss the nature, function, and trafficking of nuclear GPCR signaling complexes, as well as potential sources of endogenous and exogenous ligands. Finally, we pose a series of questions that will need to be answered in the coming years to confirm and extend this as a new paradigm for GPCR signaling.     

INTER‐ETHICS: TOWARDS AN INTERACTIVE AND INTERDEPENDENT BIOETHICS

Since its origin bioethics has been a specialized, academic discipline, focussing on moral issues, using a vast set of globalized principles and rational techniques to evaluate and guide healthcare practices. With the emergence of a plural society, the loss of faith in experts and authorities and the decline of overarching grand narratives and shared moralities, a new approach to bioethics is needed. This approach implies a shift from an external critique of practices towards embedded ethics and interactive practice improvement, and from a legal defence of rights towards fostering interdependent practices of responsibility. This article describes these transitions within bioethics in relation to the broader societal and cultural dynamics within Western societies, and traces the implications for the methodologies and changing roles of the bioethicist. The bioethicist we foresee is not just a clever expert but also a relationally sensitive person who engages stakeholders in reciprocal dialogues about their practice of responsibility and helps to integrate various sorts of knowledge (embodied, experiential, visual, and cognitive‐scientific). In order to illustrate this new approach, we present a case study. It concerns a project focusing on an innovation in elderly care, based on the participation of various stakeholders, especially older people themselves.     

EMPIRICAL ETHICS AND ITS ALLEGED META-ETHICAL FALLACIES

This paper analyses the concept of empirical ethics as well as three meta-ethical fallacies that empirical ethics is said to face: the is-ought problem, the naturalistic fallacy and violation of the fact-value distinction. Moreover, it answers the question of whether empirical ethics (necessarily) commits these three basic meta-ethical fallacies.