Mitochondria and peroxisomes: Are the ‘Big Brother’ and the ‘Little Sister’ closer than assumed?

Mitochondria and peroxisomes are essential subcellular organelles in mammals. Despite obvious differences, both organelles display certain morphological and functional similarities. Recent studies have elucidated that these highly dynamic and plastic organelles share components of their division machinery. Mitochondria and peroxisomes are metabolically linked organelles, which are cooperating and cross-talking. This review addresses the dynamics and division of mitochondria and peroxisomes as well as their functional similarities to provide insight as to why these organelles share the fission machinery in evolutionary aspects.     

Competitive exclusion: phylogeography’s ‘elephant in the room’?

Phylogeographic and evolutionary research programmes have successfully elucidated compelling genetic signatures of earth history. Particularly influential achievements include the demonstration of postglacial recolonization patterns for high-latitude taxa and phylogenetic demonstration of the 'progression rule' along oceanic island chains such as Hawaii. While both of these major biogeographic patterns clearly rely on rapid dispersal over long distances, their phylogeographic detection also apparently relies on the competitive exclusion of secondary dispersers. Such exclusion could occur either between or within species and might reflect fitness differences between lineages or, alternatively, neutral demographic processes (e.g. 'high-density blocking'). Regardless, such spatial genetic patterns would be rapidly eroded were it not for the failure of subsequent dispersers to contribute genetically to newly colonized populations. In addition to its role in revealing colonization patterns, competitive exclusion may also explain the maintenance of historic phylogeographic disjunctions long after the original physical barriers to dispersal have ceased to exist. Additionally, some of the most persuasive evidence of competitive exclusion comes from studies of anthropogenic extinction, where surviving lineages have subsequently expanded their ranges, apparently benefitting from the demise of their prehistoric sisters. Broadly, these biogeographic paradigms are united by the 'disconnect' between dispersal and colonization success, the latter being heavily influenced by inter- and intraspecific competition. Despite its apparent importance, such exclusion (especially within species) has received virtually no attention in the phylogeographic literature. Future studies should aim to test directly for the role of competitive exclusion in constraining the biogeography of highly dispersive taxa.     

‘Lymphocyte-like’cells in ascidians: Precursors for vertebrate lymphocytes?

There has been much speculation that the evolutionary precursors of vertebrate lymphocytes may exist in the ascidians (proto chordates), but conclusive evidence has remained elusive especially as membrane bound immunoglobulin has not been detected in any invertebrate. This paper reviews new evidence which indicates that the ‘lymphocyte-like’ cells in ascidians have functional, as well as morphological, similarities with vertebrate lymphocytes. Firstly, these cells have been linked with in vivo non-self recognition events such as allograft rejection in solitary ascidians and non-fusion reactions between colonial ascidians. Secondly, they have been shown to be cytotoxic towards xenogenic targets in vitro and to use cytolytic mechanisms similar to those of cytotoxic T-cells. Thirdly, they are able to proliferate in vitro in response to mitogens or allogeneic cells. It is therefore suggested that, apart from immunoglobulin production and clonal selection, there is persuasive evidence that the ‘lymphocyte-like’ cells of ascidians constitute a primordial form of vertebrate lymphocyte.     

The concepts of ‘plant functional types’ and ‘functional diversity’ in lake phytoplankton – a new understanding of phytoplankton ecology?

1. This is a discussion of the applicability to the phytoplankton of the concepts of ‘plant functional types’ (PFTs) and ‘functional diversity’ (FD), which originated in terrestrial plant ecology. 2. Functional traits driving the performance of phytoplankton species reflect important processes such as growth, sedimentation, grazing losses and nutrient acquisition. 3. This paper presents an objective, mathematical way of assigning PFTs and measuring FD. Ecologists can use this new approach to investigate general hypotheses [e.g. the intermediate disturbance hypothesis (IDH), the insurance hypothesis and synchronicity phenomena] as, for example, in its original formulation the IDH makes its predictions based on FD rather than species diversity.     

Omarakana revisited,or ‘do dual organizations exist?’ in the Trobriands

Omarakana is arguably the most renowned village in the Trobriand and anthropological worlds. It is the very centre and wellspring of the North Kiriwinan universe and thus a sacred site, serving as the home of the Tabalu chiefly paramountcy. For us anthropologists, it is ground zero for our field methodology, thanks to Malinowski's pioneering research, and probably Melanesia's most hierarchical polity. Ironically, though, very little is actually known ethnographically about Omarakana's spatial layout. In this article I seek to compensate for that deficiency, arguing that Omarakana's seemingly concentric contours encode transformations of indigenous symbolism involving recurrent metaphors drawn from at least three conjoined semantic contexts of wide distribution across the Austronesian sphere and beyond: the double bisection of ‘male’ versus ‘female’; the botanical imagery of ‘base’, ‘body’, ‘tip’, and ‘fruit’; and various elements of ‘canoe’ symbolism. This alternative view of Omarakana's spatio‐temporal plan sheds new light on various additional dimensions of Trobriand sociality and cosmology while elaborating classic and contemporary anthropological theories of dualism.     

Can a ‘Silent’ Person Be a ‘Business’ Person? The Concept Mãduã in Fijian Culture

The focus of the paper is an examination of the relevance of the traditional concept mãduã for an understanding of Fijian culture, particularly in the context of modern business enterprise. The concept represents a multitude of subtle as well as clearly displayed emotions and attitudes. Though mãduã is especially relevant in situations where Fijian values are centre stage, the view put forward here is that the associated expressions and bodily postures are also relevant in modern urban contexts, where perhaps one might otherwise expect them to be discarded or at least toned down. In public discourse in Fiji, where the theme of Fijian participation in both education and business is constantly commented on and discussed, a new notion is identified, namely ‘silence’. The author suggests that it may to some degree replace and encompass mãduã The prime concern of the article, however, is to bring to the fore reflections by Fijians themselves on existential dilemmas, one of which is about how to live with mãduã in the modern context.     

Whatever happened to the ‘microtrabecular concept’?

Keith Porter culminated his stellar career as the founding father of biological electron microscopy by acquiring, in the late 1970s, a high-voltage electron microscope (HVEM). With this magnificent instrument he examined whole-mounts of cultured cells, and perceived within them a structured cytoplasmic matrix he named the "microtrabecular lattice". Over the next decade Porter published a series of studies, together with a team of outstanding young colleagues, which elaborated his broader "microtrabecular concept." This concept posited that microtrabeculae were real physical entities that represented the fundamental organization the cytoplasm, and that they were the physical basis of cytoplasmic motility and of cell-shape determination. The present review presents Porter's original images of microtrabeculae, after conversion to a more interpretable "digital-anaglyph" form, and discusses the rise and fall of the microtrabecular concept. Further, it explains how the HVEM images of microtrabeculae finally came to be considered as an artifact of the preparative methods Porter used to prepare whole cells for HVEM. Still, Keith's "microtrabecular concept" foretold of our current appreciation of the complexity and pervasiveness of the cytoskeleton, which has now been found by more modern methods of EM to actually be the fundamental organizing principle of the cytoplasmic matrix. During the impending eclipse of Porter's microtrabecular concept in the late 1980s, many of Keith's colleagues fondly described the cell as being filled, not with protoplasm, but with "Porterplasm." Despite the fact that Keith's view was clouded by the methods of his time, it would be fitting and apt to retain this name, still today, for the ordered matrix of cytoskeletal macromolecules that exists in the living cell. In the end, the story of what happened to Porter's microtrabecular concept should be an object lesson in scientific hubris that should humble and inform all of us in cell biology, even today--particularly when we begin to think that our most recent methods and observations are achieving "the last word".     

Does ‘gliding while gravid’ explain Rensch's rule in flying lizards?

Among species with sexual size dimorphism (SSD), taxa in which males are the larger sex have increasing SSD with increasing body size, whereas in taxa in which females are the larger sex, SSD decreases with body size: Rensch's rule. We show in flying lizards, a clade of mostly female‐larger species, that SSD increases with body size, a pattern similar to that in clades with male‐biased SSD or more evenly mixed SSD. The observed pattern in Draco appears due to SSD increasing with evolutionary changes in male body size; specifically divergence in body size among species that are in sympatric congeneric assemblages. We suggest that increasing body size, resulting in decreased gliding performance, reduces the relative gliding cost of gravidity in females, and switches sexual selection in males away from a small‐male, gliding advantage and toward selection on large size and fighting ability as seen in many other lizards. Thus, selection for large females is likely greater than selection for large males at the smaller end of the body size continuum, whereas this relationship reverses for species at the larger end of the continuum. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 270–282.     

Pocket calculator: a humdrum ‘obviator’ in Papua New Guinea?

This article examines the significance of pockets for controlling money in Highland Papua New Guinea. Contextualizing elaborate ‘systems’ for compartmentalizing monies in separate pockets, I draw upon the connection Highlanders make between transaction and skin. Pockets, I argue, offer opportunities to hide one's wealth reserves while gifting, keeping intentions opaque and leaving interlocutors guessing at the meaning of donors' speech, and forcing recipients to perceive their gift as ample. The article suggests that expectations are deliberately conventionalized in order to be exceeded, drawing parallels with Roy Wagner's notion of obviation. After characterizing Gorokan pockets and their gifting ‘logic’, I analyse how pocket‐users are themselves conventionalized as forthright or selfish in local discourse, based upon the pockets they display and where their clothes come from. Giving people clothing that includes pockets is therefore a way to regain control over their capacity to reveal wealth from their pockets.     

Quantitative floral phenology at the landscape scale: Is a comparative spatio-temporal description of ‘‘flowering landscapes’’ possible?

Entomophilous flowers form the food resources for insect pollinators. Many pollinator species forage at the landscape scale and depend on floral resources that are highly variable in space and time. We present a general model approach in which the floral resources of plant communities are estimated by the floral phenology and the cover of entomophilous plant species. We applied this landscape model in a case study for three landscape sections (1.5–2.2 km²) with strongly differing land-use patterns. The comparison between a conservation area and two agricultural landscapes shows extreme differences in the quantities and in the course of floral resources.

In a stepwise simplification of the landscape model we tested the effects of input data with lower spatio-temporal resolution. Even if input data for floral phenology and vegetation have a low resolution, the landscape model allows a ranking of landscape-specific floral resource potentials. The results of the case study encourage the use of landscape models to estimate floral resource potentials. The assessment of floral resource potentials may help to define this essential landscape quality for evaluation in practical nature conservation.     

The ‘kinetochore maintenance loop’—The mark of regulation?

Kinetochores can form and be maintained on DNA sequences that are normally non‐centromeric. The existence of these so‐called neo‐centromeres has posed the problem as to the nature of the epigenetic mechanisms that maintain the centromere. Here we highlight results that indicate that the amount of CENP‐A at human centromeres is tightly regulated. It is also known that kinetochore assembly requires sister chromatid cohesion at mitosis. We therefore suggest that separation or stretching between the sister chromatids at metaphase reciprocally determines the amount of centromere assembly in the subsequent interphase. This reciprocal relationship forms the basis of a negative feedback loop that could precisely control the amount of CENP‐A and faithfully maintain the presence of a kinetochore over many cell divisions. We describe how the feedback loop would work, propose how it could be tested experimentally and suggest possible components of its mechanism.     

Territoriality in Lake Eyre Dragons Ctenophorus maculosus: are Males ‘Superterritorial’?

The Australian Lake Eyre dragon, Ctenophorus maculosus, lives on dry salt lakes in the Australian interior. An unusual characteristic of this habitat is that windblown insects are the major food resource, which makes it impossible for males to defend site-related resources. Male territory size is not correlated to male size; thus, males do not seem to defend trophic territories in relation to their own energy demands. Instead, males with higher densities of lookout sites have larger territories, and males with larger territories have more mates. In consequence, males primarily seem to guard sexual resources on territories that are not economically defensible from a trophic point of view; males appear to conform to the concept of ‘superterritoriality’ (sensu Stamps 1983).     

‘SETTING A PRINCIPLED BOUNDARY’? EUTHANASIA AS A RESPONSE TO ‘LIFE FATIGUE’

The Dutch case of Brongersma presents novel challenges to the definition and evaluation of voluntary euthanasia since it involved a doctor assisting the suicide of an individual who was (merely?) ‘tired of life’. Legal officials had called on the courts to ‘set a principled boundary’, excluding such cases from the scope of permissible voluntary euthanasia, but they arguably failed. This failure is explicable, however, since the case seems justifiable by reference to the two major principles in favour of that practice, respect for autonomy and beneficence. Ultimately, it will be argued that those proponents of voluntary euthanasia who are wary of its use in such circumstances may need to draw upon ‘practical’ objections, in order to erect an otherwise arbitrary perimeter. Furthermore, it will be suggested that the issues raised by the case are not peculiarly Dutch in nature and that, therefore, there are lessons here for other jurisdictions too.     

‘Should I stay or should I go?’: myosin V function in organelle trafficking

Actin- and microtubule-based motors can propel different cargos along filaments. Within cells, they control the distribution of membrane-bound compartments by performing complementary tasks. Organelles make long journeys along microtubules, with class V myosins ensuring their capture and their dispersal in actin-rich regions. Myosin Va is recruited on to diverse organelles, such as melanosomes and secretory vesicles, by a mechanism involving Rab GTPases. The role of myosin Va in the recruitment of secretory vesicles at the plasma membrane reveals that the cortical actin network cannot merely be seen as a physical barrier hindering vesicle access to release sites. In neurons, myosin Va controls the targeting of IP(3) (inositol 1,4,5-trisphosphate)-sensitive Ca(2+) stores to dendritic spines and the transport of mRNAs. These defects probably account for the severe neurological symptoms observed in Griscelli syndrome due to mutations in the MYO5A gene.     

‘Accelerated aging’: a primrose path to insight?

Organism envy afflicts most researchers who work on aging in mice; how frustrating it is to see the worm and fly biologists nail down milestone after milestone, citation after citation! Surely genetic trickery can produce mice that age in a comparable jiffy? Alas, our near‐total ignorance of what times the aging process makes it hard to guess what genes to tweak, if indeed aging can be mimicked a presto. Building a case that a given short‐lived mutant ages quickly is a steep and thorny path, requiring more than just plucking a symptom here and there from a list of things that sometimes go wrong in old people or old mice. The hallmark of aging is that a lot goes wrong more or less at the same time, in 2‐year‐old mice, 10‐year‐old dogs and 70‐year‐old people. Finding ways to damage one or two systems in a 6‐week or 6‐month‐old mouse is not too hard to do, but the implications of such studies for improved understanding of aging per se are at best indirect and at worst imaginary and distracting.     

GENDER AND ETHICS COMMITTEES: WHERE’S THE ‘DIFFERENT VOICE’?

Prominent international and national ethics commissions such as the UNESCO International Bioethics Committee rarely achieve anything remotely resembling gender equality, although local research and clinical ethics committees are somewhat more egalitarian. Under‐representation of women is particularly troubling when the subject matter of modern bioethics so disproportionately concerns women’s bodies, and when such committees claim to derive ‘universal’ standards. Are women missing from many ethics committees because of relatively straightforward, if discriminatory, demographic factors? Or are the methods of analysis and styles of ethics to which these bodies are committed somehow ‘anti‐female’? It has been argued, for example, that there is a ‘different voice’ in ethical reasoning, not confined to women but more representative of female experience. Similarly, some feminist writers, such as Evelyn Fox Keller and Donna Haraway, have asked difficult epistemological questions about the dominant ‘masculine paradigm’ in science. Perhaps the dominant paradigm in ethics committee deliberation is similarly gendered? This article provides a preliminary survey of women’s representation on ethics committees in eastern and western Europe, a critical analysis of the supposed ‘masculinism’ of the principlist approach, and a case example in which a ‘different voice’ did indeed make a difference.