Community structure of Diplostomum spp. (Digenea: Diplostomidae) in eyes of fish: Main determinants and potential interspecific interactions

Parasite communities in freshwater fish vary annually and seasonally and can be influenced by the length, age, sex and phylogeny of hosts, and by associations among parasite species. We assessed the influence of these factors in species of Diplostomum in the eyes of 828 fish in 20 different species collected in a single lake in early summer or autumn over a 5 year interval. Strong negative associations were found between five pairs of Diplostomum spp. and associations were strongest among abundant species. Most interspecific associations occurred among species inhabiting the lens, suggesting competitive interactions. However, the strongest association occurred between two Diplostomum spp. that inhabit different tissues (i.e., the vitreous humour and lens), indicating processes other than direct competition. Seasonal variation was small compared with inter-annual variation. Infection intensities were high in 2006 and decreased dramatically in 2010 and 2011. Infracommunity composition and structure showed no clear correspondence to the ecology or phylogeny of host species. Host length and age, but not sex, had significant effects on the structure of Diplostomum infracommunities in lenses. However, a significant amount of variance in lens infracommunities could not be explained, indicating the potential importance of other factors such as resistance or exposure in determining infracommunity structure.     

The interactive effects of competition and predation risk on dispersal in an insect

Dispersal dynamics have significant consequences for ecological and evolutionary processes. Previous work has demonstrated that dispersal can be context-dependent. However, factors affecting dispersal are typically considered in isolation, despite the probability that individuals make dispersal decisions in response to multiple, possibly interacting factors. We examined whether two ecological factors, predation risk and intraspecific competition, have interactive effects on dispersal dynamics. We performed a factorial experiment in mesocosms using backswimmers (Notonecta undulata), flight-capable, semi-aquatic insects. Emigration rates increased with density, and increased with predation risk at intermediate densities; however, predation had minimal effects on emigration at high and low densities. Our results indicate that factorial experiments may be required to understand dispersal dynamics under realistic ecological conditions.     

Isolation and characterization of polymorphic microsatellite loci from the Dungeness crab Cancer magister

The Dungeness crab, Cancer magister, is the focus of one of the most intensely harvested fisheries in North America. Given its economic importance, there is considerable interest in assessing the degree and spatial pattern of genetic structure in C. magister. To that end, we developed a series of 17 hypervariable microsatellite loci. Six of these 17 loci could be amplified in a single multiplex PCR reaction. Using dye‐labelled primers all six loci can be coamplified and scored simultaneously on an automated sequencer. The ability to multiplex multiple loci greatly increases the ease and speed of genotyping for this species.     

Density‐dependent offspring interactions do not explain macroevolutionary scaling of adult size and offspring size

Most life forms exhibit a correlated evolution of adult size (AS) and size at independence (SI), giving rise to AS–SI scaling relationships. Theory suggests that scaling arises because relatively large adults have relatively high reproductive output, resulting in strong density‐dependent competition in early life, where large size at independence provides a competitive advantage to juveniles. The primary goal of our study is to test this density hypothesis, using large datasets that span the vertebrate tree of life (fishes, amphibians, reptiles, birds, and mammals). Our secondary goal is to motivate new hypotheses for AS–SI scaling by exploring how subtle variation in life‐histories among closely related species is associated with variation in scaling. Our phylogenetically informed comparisons do not support the density hypothesis. Instead, exploration of AS–SI scaling among life‐history variants suggests that steeper AS–SI scaling slopes are associated with evolutionary increases in size at independence. We suggest that a positive association between size at independence and juvenile growth rate may represent an important mechanism underlying AS–SI scaling, a mechanism that has been underappreciated by theorists. If faster juvenile growth is a consequence of evolutionary increases in size at independence, this may help offset the cost of delayed maturation, leading to steeper AS–SI scaling slopes.     

Evaluation of Perennial Glycine Species for Response to Meloidogyne Incognita,Rotylenchulus Reniformis,and Pratylenchus Penetrans

Root-knot (Meloidogyne incognita (Kofoid & White) Chitwood), reniform (Rotylenchulus reniformis Lindford & Oliveira), and lesion nematodes (Pratylenchus penetrans (Cobb) Filipjev & Schuurmans Stekhoven) are plant-parasitic nematodes that feed on soybean (Glycine max (L.) Merr.) roots, limiting seed production. The availability of resistance in soybeans to these nematodes is limited. However, new sources of resistance can be discovered in wild relatives of agronomic crops. Perennial Glycine species, wild relatives to soybean, are a source of valuable genetic resources with the potential to improve disease resistance in soybean. To determine if these perennials have resistance against nematodes, 18 accessions of 10 perennial Glycine species were evaluated for their response to M. incognita and R. reniformis, and eight accessions of six perennial Glycine species were evaluated for their response to P. penetrans. Pot experiments were conducted for M. incognita and R. reniformis in a growth chamber and in vitro experiments were conducted for P. penetrans. We found both shared and distinct interactions along the resistance-susceptible continuum in response to the three plant-parasitic nematode species. Ten and 15 accessions were classified as resistant to M. incognita based on eggs per gram of root and gall index, respectively. Among them, G. tomentella plant introductions (PIs) 446983 and 339655 had a significantly lower gall index than the resistant soybean check cv. Forrest. Of three R. reniformis resistant accessions identified in this study, G. tomentella PI 441001 showed significantly greater resistance to R. reniformis than the resistant check cv. Forrest based on nematodes per gram of root. In contrast, no resistance to P. penetrans was recorded in any perennial Glycine species.     

Quantitative measurement of the total, peroxyl radical-trapping antioxidant capability of human blood plasma by controlled peroxidation. The important contribution made by plasma proteins

Plasma obtained from fasted humans has been analysed for total radical-trapping antioxidant content by subjecting it to controlled peroxidation using the thermal decomposition of water-soluble azobis (2-amidinopropane hydrochloride) at 37 degrees C to produce peroxyl radicals at a known, steady rate. It is found that the total radical-trapping antioxidant content is rather similar for the 7 subjects that have been tested and, furthermore, it is 10-20-times larger than the effect attributable to vitamin E alone. Although it is shown that urate and ascorbate augment the contribution from vitamin E, their contributions (21-34 and 0-2%, respectively) still leave 57-73% of the total antioxidant content unaccounted for. Evidence is presented to show that this previously unrecognized large reserve of antioxidant capacity is attributable to the plasma proteins.     

Voluntary Breath-hold Technique for Reducing Heart Dose in Left Breast Radiotherapy

Breath-holding techniques reduce the amount of radiation received by cardiac structures during tangential-field left breast radiotherapy. With these techniques, patients hold their breath while radiotherapy is delivered, pushing the heart down and away from the radiotherapy field. Despite clear dosimetric benefits, these techniques are not yet in widespread use. One reason for this is that commercially available solutions require specialist equipment, necessitating not only significant capital investment, but often also incurring ongoing costs such as a need for daily disposable mouthpieces. The voluntary breath-hold technique described here does not require any additional specialist equipment. All breath-holding techniques require a surrogate to monitor breath-hold consistency and whether breath-hold is maintained. Voluntary breath-hold uses the distance moved by the anterior and lateral reference marks (tattoos) away from the treatment room lasers in breath-hold to monitor consistency at CT-planning and treatment setup. Light fields are then used to monitor breath-hold consistency prior to and during radiotherapy delivery.     

Effector-mediated ERM activation locally inhibits RhoA activity to shape the apical cell domain

Activated ezrin-radixin-moesin (ERM) proteins link the plasma membrane to the actin cytoskeleton to generate apical structures, including microvilli. Among many kinases implicated in ERM activation are the homologues LOK and SLK. CRISPR/Cas9 was used to knock out all ERM proteins or LOK/SLK in human cells. LOK/SLK knockout eliminates all ERM-activating phosphorylation. The apical domains of cells lacking LOK/SLK or ERMs are strikingly similar and selectively altered, with loss of microvilli and with junctional actin replaced by ectopic myosin-II–containing apical contractile structures. Constitutively active ezrin can reverse the phenotypes of either ERM or LOK/SLK knockouts, indicating that a central function of LOK/SLK is to activate ERMs. Both knockout lines have elevated active RhoA with concomitant enhanced myosin light chain phosphorylation, revealing that active ERMs are negative regulators of RhoA. As RhoA-GTP activates LOK/SLK to activate ERM proteins, the ability of active ERMs to negatively regulate RhoA-GTP represents a novel local feedback loop necessary for the proper apical morphology of epithelial cells.     

Comparison of the ligand binding properties of two homologous rat apocellular retinol-binding proteins expressed in Escherichia coli

Cellular retinol-binding protein (CRBP) and cellular retinol-binding protein II (CRBP II) are 132-residue cytosolic proteins which have 56% amino acid sequence identity and bind all-trans-retinol as their endogenous ligand. They belong to a family of cytoplasmic proteins which have evolved to bind distinct hydrophobic ligands. Their patterns of tissue-specific and developmental regulation are distinct. We have compared the ligand binding properties of rat apo-CRBP and apo-CRBP II that have been expressed in Escherichia coli. Several observations indicate that the E. coli-derived apoproteins are structurally similar to the native rat proteins: they co-migrate on isoelectric focusing gels; and when complexed with all-trans-retinol, their absorption and excitation/emission spectra are nearly identical to those of the authentic rat holoproteins. Comparative lifetime and acrylamide quenching studies suggest that there are differences in the conformations of apo-CRBP and apo-CRBP II. The interaction of E. coli-derived apo-CRBP and apo-CRBP II with a variety of retinoids was analyzed using spectroscopic techniques. Both apoproteins formed high affinity complexes with all-trans-retinol (K'd approximately 10 nM). In direct binding assays, all-trans-retinal bound to both apoproteins (K'd approximately 50 nM for CRBP; K'd approximately 90 nM for CRBP II). However, all-trans-retinal could displace all-trans-retinol bound to CRBP II but not to CRBP. These observations suggests that there is a specific yet distinct interaction between these two proteins and all-trans-retinal. Apo-CRBP and apo-CRBP II did not demonstrate significant binding to either retinoic acid or methyl retinoate, an uncharged derivative of all-trans-retinoic acid. This indicates that the carboxymethyl group of methyl retinoate cannot be sterically accommodated in their binding pockets and that failure to bind retinoic acid probably is not simply due to the negative charge of its C-15 carboxylate group. Finally, neither all-trans-retinol nor retinoic acid bound to E. coli-derived rat intestinal fatty acid-binding protein, a homologous protein whose tertiary structure is known. Together, the data suggest that these three family members have acquired unique functional capabilities.