Protozoans—the first food of larval herring (Clupea harengus L.)?

In short-run experiments herring larvae at the end of the yolk sac stage (S_L 6.5 to 8.5 m) were fed with maize and potato starch to investigate the effect of particle size on food selection. About 20% of the larvae ingested these particles during the experiments. In the case of maize starch (3 to 26 μm grain size) the size classes from 14 to 25 μm and in the case of potato starch (5 to 80 μm) the size classes larger than 29 μm were preferred. The highest numbers of ingested grains per larva were 150 maize starch grains and 57 potato starch grains. The selective uptake of these size classes leads to the conclusion that planktonic organisms in this size range—in other words mostly protozoans—may play an important role as a first food source of herring larvae.     

Larval Planktotrophy—A Primitive Trait in the Bilateria?

The concept of Gösta Jägersten of a primary biphasic metazoan life-cycle, consisting of a planktotrophic larva and a benthic adult, forms the basis for several theories on metazoan phylogeny. In this paper the assumed planktotrophic life-style of the larva is critically analyzed and reconsidered. It is shown, in particular for the Mollusca, that a biphasic life-cycle with a lecithotrophic larva is probably the plesiomorphic condition. Character distribution and structural data suggest a parallel evolution of the downstream collecting system used in planktotrophic larvae or filter-feeding adults of gastropods, bivalves and other spiralian or aschelminth taxa. In the basic metazoans (Parazoa, Placozoa, coelenterates) direct or lecithotrophic development dominates by far. For the acoelomate (Platyhelminthes, Gnathostomulida) and pseudocoelomate taxa direct development is probably the plesiomorphic condition. The structural similarities of the upstream collecting system in tentaculate and deuterostome phyla may also be explained by parallel events of heterochrony out of an ancestor with adult filter-feeding. The main conclusion of this survey is that larval planktotrophy is likely to be secondary and not a plesiomorphic condition among the Bilateria. Accordingly, theories which are based on the assumed plesiomorphy of larval planktotrophy of the Bilateria, need careful reevaluation.     

Repair or regenerate—how can we tip the balance?

The fourth EMBO conference on ‘The Molecular and Cellular Basis of Regeneration and Repair’, held in September 2012, brought together researchers from both the regeneration and wound‐healing fields. The meeting spanned a wide range of research topics from basic science to clinical application, and a veritable melting pot of model organisms and approaches resulted in an excellent fourth conference in this series.     

Do Mediterranean‐type ecosystems have a common history?—Insights from the Buckthorn family (Rhamnaceae)

Mediterranean‐type ecosystems (MTEs) are remarkable in their species richness and endemism, but the processes that have led to this diversity remain enigmatic. Here, we hypothesize that continent‐dependent speciation and extinction rates have led to disparity in diversity between the five MTEs of the world: the Cape, California, Mediterranean Basin, Chile, and Western Australia. To test this hypothesis, we built a phylogenetic tree for 280 Rhamnaceae species, estimated divergence times using eight fossil calibrations, and used Bayesian methods and simulations to test for differences in diversification rates. Rhamnaceae lineages in MTEs generally show higher diversification rates than elsewhere, but speciation and extinction dynamics show a pattern of continent‐dependence. We detected high speciation and extinction rates in California and significantly lower extinction rates in the Cape and Western Australia. The independent colonization of four of five MTEs may have occurred conterminously in the Oligocene/Early Miocene, but colonization of the Mediterranean Basin happened later, in the Late Miocene. This suggests that the in situ radiations of these clades were initiated before the onset of winter rainfall in these regions. These results indicate independent evolutionary histories of Rhamnaceae in MTEs, possibly related to the intensity of climate oscillations and the geological history of the regions.     

Interrupting the inflammatory cycle in chronic diseases—Do gap junctions provide the answer?

A number of chronic diseases, including neurodegenerative, cardiovascular and metabolic disorders, are associated with genetic susceptibility. Some may originate on exposure to an environmental stimulus. Regardless of genetic predisposition or external stimulus, these chronic diseases, once triggered, share an inflammatory component making them effectively persistent "wounds". There is also increasing evidence that the presence of one disease can cause activation of another apparently unrelated disease, leading to multiple disorders via activation of an immune response that 'fast forwards' disease progression. Here we review common aspects of a number of chronic disease conditions, and put forward the proposal that gap junction modulation may provide an opportunity to break the inflammatory cycle that sustains and links these disorders.     

Phantoms of Gondwana?—phylogeny of the spider subfamily Mynogleninae (Araneae: Linyphiidae)

This is the first genus‐level phylogeny of the subfamily Mynogleninae. It is based on 190 morphological characters scored for 44 taxa: 37 mynoglenine taxa (ingroup) representing 15 of the 17 known genera and seven outgroup taxa representing the subfamilies Stemonyphantinae, Linyphiinae (Linyphiini and Micronetini), and Erigoninae, and a representative of the family Pimoidae, the sister‐group to Linyphiidae. No fewer than 147 of the morphological characters used in this study are new and defined for this study, and come mainly from male and female genitalia. Parsimony analysis with equal weights resulted in three most parsimonious trees of length 871. The monophyly of the subfamily Mynogleninae and the genera Novafroneta, Parafroneta, Laminafroneta, Afroneta, Promynoglenes, Metamynoglenes, and Haplinis are supported, whereas Pseudafroneta is paraphyletic. The remaining seven mynoglenine genera are either monotypic or represented by only one taxon. Diagnoses are given for all genera included in the analysis. The evolution of morphological traits is discussed and we summarize the diversity and distribution patterns of the 124 known species of mynoglenines. The preferred topology suggests a single origin of mynoglenines in New Zealand with two dispersal events to Africa, and does not support Gondwana origin.     

Does the accumulation of trace metals in crustaceans affect their ecology—the amphipod example?

Crustaceans, like all aquatic invertebrates, take up and accumulate metals from a wide range of sources and the trace metal concentrations within their tissues and bodies show great variability. Trace metal uptake in crustaceans occurs from the water and food, either of which may be affected by the physico-chemical properties of the sediment. Accumulated metal concentrations in amphipods are contrasted with those of other crustaceans and examples are given to show how external and internal factors affect bioaccumulation. One of the major pathways for the uptake of trace metals is from solution directly through permeable surfaces including the gills. Changes in salinity and oxygen tension can modify the uptake characteristics from solution particularly in the case of interstitial water within sediments. Infaunal amphipods have direct contact with the sediment and the bioavailabilities of trace metals depend on the strength of the metal binding which is determined by a combination of properties including grain size, organic content, the presence of metals such as lead and iron as well as other ambient environmental conditions. Metal concentrations within amphipod bodies reflect the bioavailabilities of trace metals in their habitat. Body size is one of the major factors contributing to individual variability in trace metal concentrations within species. For some amphipod species, there are differences in trace metal accumulation with gender, breeding and developmental stage. In amphipods, accumulated body metal concentrations are the best biomarkers for environmental metal availabilities. Metal accumulation affects the ecology of crustaceans as a consequence of the energy costs associated with excreting and/or detoxifying the incoming metals. If the costs are significant, then this may result in reduced growth and reproduction. The effects of accumulated metals on communities have yet to be determined. Accumulated metals in crustacean prey species may be transferred along the food chain, but biomagnification in fish appears unlikely. One of the main ecological challenges is the need to link molecular biomarkers with ecologically relevant life history characteristics including growth, survival, reproduction and recruitment.     

Review: Transport of tRNA out of the Nucleus—Direct Channeling to the Ribosome?

Although tRNA was the first substrate whose export from the nuclei of eukaryotic cells had been shown to be carrier-mediated and active, it has only been in the last 2 years that the first mechanistic details of this nucleocytoplasmic transport pathway have begun to emerge. A member of the importin/karyopherin β superfamily, Los1p in yeast and Xpo-t in vertebrates, has been shown to export tRNA in cooperation with the small GTPase Ran (Gsp1p) from the nucleus into the cytoplasm, where tRNA becomes available for translation. However, Los1p is not essential for viability in yeast cells, suggesting that alternative tRNA export pathways exist. Recent results show that aminoacylation and a translation factor are also required for efficient nuclear tRNA export. Thus, protein translation and nuclear export of tRNA appear to be coupled processes.     

Integral role of the I′-helix in the function of the “inactive” C-terminal domain of catalase–peroxidase (KatG)

Catalase–peroxidases (KatGs) have two peroxidase-like domains. The N-terminal domain contains the heme-dependent, bifunctional active site. Though the C-terminal domain lacks the ability to bind heme or directly catalyze any reaction, it has been proposed to serve as a platform to direct the folding of the N-terminal domain. Toward such a purpose, its I′-helix is highly conserved and appears at the interface between the two domains. Single and multiple substitution variants targeting highly conserved residues of the I′-helix were generated for intact KatG as well as the stand-alone C-terminal domain (KatG^C). Single variants of intact KatG produced only subtle variations in spectroscopic and catalytic properties of the enzyme. However, the double and quadruple variants showed substantial increases in hexa-coordinate low-spin heme and diminished enzyme activity, similar to that observed for the N-terminal domain on its own (KatG^N). The analogous variants of KatG^C showed a much more profound loss of function as evaluated by their ability to return KatG^N to its active conformation. All of the single variants showed a substantial decrease in the rate and extent of KatG^N reactivation, but with two substitutions, KatG^C completely lost its capacity for the reactivation of KatG^N. These results suggest that the I′-helix is central to direct structural adjustments in the adjacent N-terminal domain and supports the hypothesis that the C-terminal domain serves as a platform to direct N-terminal domain conformation and bifunctionality.     

Retromer and the cation‐independent mannose 6‐phosphate receptor—Time for a trial separation?

The retromer cargo‐selective complex (CSC) comprising Vps35, Vps29 and Vps26 mediates the endosome‐to‐Golgi retrieval of the cation‐independent mannose 6‐phosphate receptor (CIMPR). Or does it? Recently published data have questioned the validity of this long‐established theory. Here, the evidence for and against a role for the retromer CSC in CIMPR endosome‐to‐Golgi retrieval is examined in the light of the new data that the SNX‐BAR dimer is actually responsible for CIMPR retrieval.      

Spontaneous conformational change within the prion protein—implications for disease pathogenesis?

A recent paper by Leclerc et al(1) describes how recombinant hamster prion protein can undergo a spontaneous change in conformation to a structure that has features in common with PrP(Sc). Structural change in the host prion protein, PrP(C) to an insoluble and aggregated form with increased beta-sheet content (PrP(Sc)) is central to the pathology of prion diseases.(2) A detailed understanding of the nature of these conformational changes will increase our knowledge of the molecular basis of prion pathology. These findings may have implications for how the disease is initiated and provide a format for further investigation.     

NAADP on the up in pancreatic beta cells—a sweet message?

Pancreatic beta cells secrete insulin in response to elevated plasma glucose levels in a Ca(2+)-dependent fashion. Released insulin may act on the beta cell itself to promote further insulin synthesis and release. Recent studies by Johnson and Misler,1 Masgrau et al.2 and Mitchell et al.3 provide strong evidence (1) for the existence of intracellular Ca(2+) stores sensitive to NAADP, a potent Ca(2+)-mobilizing messenger, and (2) that these Ca(2+) stores are involved in both glucose- and insulin-mediated signal transduction. NAADP may therefore play an important role in controlling secretion of insulin from pancreatic beta cells.     

Mesobuthus gibbosus (Scorpiones: Buthidae) on the island of Rhodes — hybridization between Ulysses’ stowaways and native scorpions?

Allozyme data suggest that the Rhodes population of Mesobuthus gibbosus is a hybrid population of recent origin. Namely, it is a mixture between an autochthonous population and an artificially introduced population probably from the Greek mainland. All samples were mainly composed of F1 hybrid genotypes and genotypes either fixed for autochthonous or introduced alleles. Back-cross hybrid genotypes were very rare. Mitochondrial DNA analysis, in contrast, revealed only one group of closely related haplotypes that are unique for the Rhodes populations, thus suggesting asymmetric introgression of the two marker classes.     

Magnetic field from spot welding equipment—is the basic restriction exceeded?

A point measurement of the magnetic field (MF) near a typical spot welding machine showed that the magnetic flux density was above the ICNIRP reference level. To investigate if the basic restrictions were exceeded, the induced body currents in a full 3D human model were calculated. It was found that at an operator position of 34 cm away from the machine the maximum induced current density was below the ICNIRP basic restriction. But if the operator was closer to the machine, the basic restriction was exceeded. An important finding of the present article is that the basic restriction can be exceeded although the MF spatially averaged over the whole body is well below the reference level.