Cyclic strain-mediated matrix metalloproteinase regulation within the vascular endothelium: a force to be reckoned with

The vascular endothelium is a dynamic cellular interface between the vessel wall and the bloodstream, where it regulates the physiological effects of humoral and biomechanical stimuli on vessel tone and remodeling. With respect to the latter hemodynamic stimulus, the endothelium is chronically exposed to mechanical forces in the form of cyclic circumferential strain, resulting from the pulsatile nature of blood flow, and shear stress. Both forces can profoundly modulate endothelial cell (EC) metabolism and function and, under normal physiological conditions, impart an atheroprotective effect that disfavors pathological remodeling of the vessel wall. Moreover, disruption of normal hemodynamic loading can be either causative of or contributory to vascular diseases such as atherosclerosis. EC-matrix interactions are a critical determinant of how the vascular endothelium responds to these forces and unquestionably utilizes matrix metalloproteinases (MMPs), enzymes capable of degrading basement membrane and interstitial matrix molecules, to facilitate force-mediated changes in vascular cell fate. In view of the growing importance of blood flow patterns and mechanotransduction to vascular health and pathophysiology, and considering the potential value of MMPs as therapeutic targets, a timely review of our collective understanding of MMP mechanoregulation and its impact on the vascular endothelium is warranted. More specifically, this review primarily summarizes our current knowledge of how cyclic strain regulates MMP expression and activation within the vascular endothelium and subsequently endeavors to address the direct and indirect consequences of this on vascular EC fate. Possible relevance of these phenomena to vascular endothelial dysfunction and pathological remodeling are also addressed.     

To be a Juvenile and Not to be a Larva: An Attempt to Synthesize

The question - when does a fish becomes a juvenile - might seem strange to some, and even totally worthless, mainly to those fish and fishery biologists who designate all the small ontogenetic stages of fishes by the banal term fry (for a commentary on this unfortunate term, see Balon 1990). Despite this, a group of predominantly younger scientists met at a workshop in Bratislava to exchange views on this topic. Ontogeny is a process during which one event is related to another and everything is related to everything else. Therefore, besides the title subject, the participants of the workshop discussed also such topics as fish metamorphosis, whether the larva period begins with hatching or with the onset of exogenous feeding, and eventually, whether fish ontogeny is saltatory or otherwise.     

Not just fuel: energy stores are correlated with immune function and oxidative damage in a long-distance migrant

In many animals,catabolic and anabolic periods are temporally separated.Migratory birds alternate energy expenditure during flight with energy accumulation during stopover.The size of the energy stores at stopover affects the decision to resume migration and thus the temporal organization of migration.We now provide data suggesting that it is not only the size of the energy stores per se that may influence migration scheduling,but also the physiological consequences of flying.In two subspecies of the northern wheatear Oenanthe oenanthe,a long-distance migrant,estimated energy stores at a stopover during autumn migration were positively related with both constitutive innate and acquired immune function,and negatively related with oxidative damage to lipids.In other words,migrants'physiological condition was associated with their energetic condition.Although time spent at stopover before sampling may have contributed to this relationship,our results suggest that migrants have to trade-off the depletion of energy stores during flight with incurring physiological costs.This will affect migrants'decisions when to start and when to terminate a migratory flight.The physiological costs associated with the depletion of energy stores may also help explaining why migrants often arrive at and depart from stopover sites with larger energy stores than expected.We propose that studies on the role of energy stores as drivers of the temporal organization of(avian)migration need to consider physiological condition,such as immunological and oxidative states.     

Journey into the past: using cryogenically stored samples to reconstruct the invasion history of the quagga mussel (Dreissena rostriformis) in German river systems

Knowledge about the spatial–temporal dynamics of biological invasions often remains incomplete, because precise information about the invaders’ arrival dates is rare. This applies to the quagga mussel, which has become one of the most successful invasive species in Western European freshwaters. We here used cryogenically stored Dreissena samples from the German Environmental Specimen Bank to reconstruct the colonization history of the quagga mussel in German river systems. Our retrospective genetic analysis significantly improved upon previous findings of when the quagga mussel arrived in Germany and can be used as chronological landmarks to reconstruct its range expansion. The discovery of Dreissena rostriformis in 2004 in the Rhine River near Koblenz presented the first record of this species not only in Germany, but also in Western Europe. Our results show that the quagga mussel had already invaded not only large parts of the Rhine and the Danube, but also the Elbe River. This demonstrates the value of cryobanked biological samples for the retrospective analysis of biological ‘pollution’ through alien invasive species.     

The history of hesperopithecus: the human-ape link that turned out to be a pig.

Nebraska Man was a fossil discovery that was regarded by several leading experts as important in understanding evolutionary history. The only evidence for this anthropod was a single tooth (which turned out to be a pigs' tooth). The discovery and controversy surrounding the Nebraska Man (Hesperopithecus haroldcookii hominoidea) fossil find and its importance in history are reviewed. Its supporters' writings reveal the critical role that preconceptions played in interpreting the limited evidence. Nebraska Man provides a valuable lesson on the importance of presumptions in interpreting evidence in the field of human origins. It also stresses the need for careful evaluation of the empirical evidence for new ideas, and the danger of going beyond what the facts warrant.     

The past and present of sodium energetics: may the sodium-motive force be with you

All living cells routinely expel Na(+) ions, maintaining lower concentration of Na(+) in the cytoplasm than in the surrounding milieu. In the vast majority of bacteria, as well as in mitochondria and chloroplasts, export of Na(+) occurs at the expense of the proton-motive force. Some bacteria, however, possess primary generators of the transmembrane electrochemical gradient of Na(+) (sodium-motive force). These primary Na(+) pumps have been traditionally seen as adaptations to high external pH or to high temperature. Subsequent studies revealed, however, the mechanisms for primary sodium pumping in a variety of non-extremophiles, such as marine bacteria and certain bacterial pathogens. Further, many alkaliphiles and hyperthermophiles were shown to rely on H(+), not Na(+), as the coupling ion. We review here the recent progress in understanding the role of sodium-motive force, including (i) the conclusion on evolutionary primacy of the sodium-motive force as energy intermediate, (ii) the mechanisms, evolutionary advantages and limitations of switching from Na(+) to H(+) as the coupling ion, and (iii) the possible reasons why certain pathogenic bacteria still rely on the sodium-motive force.     

The response of life‐history traits to a new species in the community: a story of Drosophila parasitoids from the Rhône and Saône valleys

In the present study, we investigated the evolution of life‐history traits in the main species of a community, after the arrival of a new competitor. Two parasitoid species, Leptopilina heterotoma and Asobara tabida, are present throughout the Rhône and Saône valleys, whereas a third species, Leptopilina boulardi, is slowly extending its distribution northwards. In the presence of L. boulardi, competing parasitoids experience a higher mortality and lower host availability. Resources should thus be re‐allocated between traits according to these new factors. We compared life‐history traits of populations of L. heterotoma and A. tabida in areas with and without L. boulardi. As predicted by both Price's balanced mortality hypothesis and the theory of life‐history traits, we found that investment in reproduction is higher in southern populations for both native species, coupled with higher travelling abilities. However, only A. tabida paid their higher fecundity by a lower longevity. The absence of a clear trade‐off between these traits in L. heterotoma may be explained by a lower metabolic rate in southern populations. These results highlight the importance of the community change over climate in the evolution of life‐history traits in this parasitoid community. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Looking beyond history: the optics of German anthropology and the critique of humanism

Late nineteenth-century German anthropology had to compete for intellectual legitimacy with the established academic humanities (Geisteswissenschaften), above all history. Whereas humanists interpreted literary documents to create narratives about great civilizations, anthropologists represented and viewed objects, such as skulls or artifacts, to create what they regarded as natural scientific knowledge about so-called ‘natural peoples’—colonized societies of Africa, the Pacific, and the Americas. Anthropologists thus invoked a venerable tradition that presented looking at objects as a more certain source of knowledge than reading texts. Visual representations, especially of the colonized, not only allowed anthropologists allegedly objective insight into humanity but also put them in direct contact with popular audiences of ethnographic spectacles, exotic photography, and even pornographic images. Anthropologists thus sought to create a peculiar kind of anthropological vision that both differentiated them from humanists as ‘objective’ natural scientists but also distinguished them from the leering ‘Schaulust’ that they believed characterized popular consumption of exotic images. To do so they invented technologies of visual representation that eschewed the subject position figured by linear perspective. These novel optics dispensed with the leering subject posited by popular spectacles and the knowing subject posited by humanism and created an anti-humanist form of knowledge.     

Islands of resilience: the history of the German strong verbs from a systemic point of view

Existing accounts of the German strong verbs show notable confusion about their historical development and remarkable diversity with regard to their systemic conceptualisation. Using a principal parts approach, this paper brings out the drastic changes the system of the Germanic strong verbs has undergone since its genesis. In particular, it is shown that the loss of the paradigmatic connection between the phonological root structure of a verb and its ablaut pattern is the key alteration that transformed the strong verbs from a highly homogenous and learner-friendly system to a complicated array of inflection classes whose predictability is no longer based on the citation form stored in the mental lexicon. However, this paper also reveals that it is exactly the remnants of the old system that keep the German strong verbs together as a group and even ensure a limited degree of productivity. The conclusions drawn for a synchronic representation are that the traditional concept of inflection classes, based on the phonological root structure, may be of more value than generally believed and that the conceptualisation of the paradigms of the strong verbs involving stem forms with different ablaut grades as principal parts is supported from the diachronic as well as from the synchronic point of view.     

Bioarchaeological evidence for adaptive plasticity and constraint: Exploring life‐history trade‐offs in the human past

The Developmental Origins of Health and Disease paradigm evaluates the consequences of early life stress on health at later stages of life. Interacting with this paradigm represents a profound opportunity to leverage the lifespan and contextual approaches to human skeletal remains adopted by bioarchaeological research. Teeth and bone provide evidence for stressors experienced early in life. These events represent evidence for adaptive plasticity as Individuals survive the events through reallocation of energy to essential physiological functions, which inhibits enamel and skeletal growth. Age‐at‐death, adult body size, chronic infection, or childhood mortality may be used as covariates to better understand the physiological constraints operating on individual bodies following survival of early life stress. Contextual evidence from cemeteries provides clues to the ecological and cultural contingencies that exacerbate or mitigate the expression of these trade‐offs. Future studies should incorporate newly derived methods that provide reproducible and precise ways to evaluate early life stress, while incorporating populations that are often neglected.     

Losing ground: past history and future fate of Arctic small mammals in a changing climate

According to the IPCC, the global average temperature is likely to increase by 1.4–5.8 °C over the period from 1990 to 2100. In Polar regions, the magnitude of such climatic changes is even larger than in temperate and tropical biomes. This amplified response is particularly worrisome given that the so‐far moderate warming is already impacting Arctic ecosystems. Predicting species responses to rapid warming in the near future can be informed by investigating past responses, as, like the rest of the planet, the Arctic experienced recurrent cycles of temperature increase and decrease (glacial–interglacial changes) in the past. In this study, we compare the response of two important prey species of the Arctic ecosystem, the collared lemming and the narrow‐skulled vole, to Late Quaternary climate change. Using ancient DNA and Ecological Niche Modeling (ENM), we show that the two species, which occupy similar, but not identical ecological niches, show markedly different responses to climatic and environmental changes within broadly similar habitats. We empirically demonstrate, utilizing coalescent model‐testing approaches, that collared lemming populations decreased substantially after the Last Glacial Maximum; a result consistent with distributional loss over the same period based on ENM results. Given this strong association, we projected the current niche onto future climate conditions based on IPCC 4.0 scenarios, and forecast accelerating loss of habitat along southern range boundaries with likely associated demographic consequences. Narrow‐skulled vole distribution and demography, by contrast, was only moderately impacted by past climatic changes, but predicted future changes may begin to affect their current western range boundaries. Our work, founded on multiple lines of evidence suggests a future of rapidly geographically shifting Arctic small mammal prey communities, some of whom are on the edge of existence, and whose fate may have ramifications for the whole Arctic food web and ecosystem.     

Diverse approaches to analysing the history of human and pathogen evolution: how to tell the story of the past 70 000 years

The meeting 'Human evolution, migration and history revealed by genetics, immunity and infection', along with the follow-on satellite meeting at the Kavli Centre over the subsequent two days, brought together diverse talents. The aim was to see if new insights could be gained by bringing together those who have interests in the past 50-100 000 years of human history, overlaying the perspectives of palaeogeneticists, anthropologists, human geneticists, pathogen geneticists, immunologists, disease modellers, linguists, immunogeneticists, historians and archaeologists. It rapidly became clear that while all may agree on the broad brush-strokes including 'out-of-Africa' and the general approximations of timelines, diverse approaches may often suggest somewhat different ways of telling the story.     

Flow cytometry of bacteria: glimpses from the past with a view to the future

Measurement of bacteria and other microorganisms at the level of single cells has progressed enormously over the last couple of decades. Up to the late 1970s, there were no other means than microscopy for observation of single microorganisms, making any type of measurement very cumbersome and tedious, at best. Today, we measure several parameters simultaneously with a precision of a few per cent, and at a rate of 1000 cells per second. The first papers on the use of flow cytometry to measure bacteria appeared only in 1977, although the method had proved highly successful in studies of mammalian cells for almost a decade. There were several reasons for this relatively late introduction, including technical limitations, problems with adequate staining, and, not least, the human factor. Today, flow cytometry has a wide range of microbiological applications, ranging from studies of the bacterial cell cycle and many other cellular characteristics to assessment of antibiotic susceptibility of clinical samples, and monitoring of bacteria and other microorganisms in anything from sewage to sea water. Still, the potential of flow cytometry in microbiology is far from fully utilised. Better instruments and new stains will provide new opportunities to understand, control and exploit this vital part of the biosphere.     

Two ways to be a myrmecophilous butterfly: natural history and comparative immature‐stage morphology of two species of Theope (Lepidoptera: Riodinidae)

Symbiotic interactions between butterfly larvae and ants, termed myrmecophily, require a range of behavioural and morphological adaptations (ant‐organs). Here, using light and scanning electron microscopy, we describe the complete life cycle of two species of Theope (Lepidoptera: Riodinidae) that have contrasting ways of life. Theope thestias larvae are facultatively tended by several ant species, whereas Theope pieridoides have obligate symbiotic interactions with Azteca ants that inhabit a myrmecophytic tree. Morphological differences associated with their different degrees of intimacy with tending ants are visible from hatching. In T. thestias, the untended first‐instar larva has elongated bifurcated setae and a few tiny perforated cupola organs (PCOs), whereas in T. pieridoides, the ant‐tended first instar has short dendritic setae, larger and more numerous PCOs, and functional tentacle nectary organs (TNOs). Throughout ontogeny, T. pieridoides always shows more conspicuous ant‐organs than T. thestias, with the exception of balloon setae, which are larger and more numerous in T. thestias. In addition, mature T. pieridoides larvae have an anterior set of ant‐organs, including a new type, here described and termed anterior glandular openings (AGOs). Based on the behavioural responses of ants in contact with these structures, a new interpretation for the mechanism whereby Theope larvae can manipulate the behaviour of their tending ants is proposed. Until now, three ecological syndromes can be defined among Theope species: (1) oligophagous larvae with facultative myrmecophily; (2) monophagous larvae with obligate myrmecophily; and (3) polyphagous larvae with obligate myrmecophily. These results suggest that differences in the degree of specificity in the ant–plant interactions may have an important role in the evolution of host‐plant use in Theope. © 2013 The Linnean Society of London