Unique system of photoreceptors in sea urchin tube feet

Different sea urchin species show a vast variety of responses to variations in light intensity; however, despite this behavioral evidence for photosensitivity, light sensing in these animals has remained an enigma. Genome information of the recently sequenced purple sea urchin (Strongylocentrotus purpuratus) allowed us to address this question from a previously unexplored molecular perspective by localizing expression of the rhabdomeric opsin Sp-opsin4 and Sp-pax6, two genes essential for photoreceptor function and development, respectively. Using a specifically designed antibody against Sp-Opsin4 and in situ hybridization for both genes, we detected expression in two distinct groups of photoreceptor cells (PRCs) located in the animal's numerous tube feet. Specific reactivity of the Sp-Opsin4 antibody with sea star optic cushions, which regulate phototaxis, suggests a similar visual function in sea urchins. Ultrastructural characterization of the sea urchin PRCs revealed them to be of a microvillar receptor type. Our data suggest that echinoderms, in contrast to chordates, deploy a microvillar, r-opsin-expressing PRC type for vision, a feature that has been so far documented only in protostome animals. Surprisingly, sea urchin PRCs lack any associated screening pigment. Indeed, one of the tube foot PRC clusters may account for directional vision by being shaded through the opaque calcite skeleton. The PRC axons connect to the animal internal nervous system, suggesting an integrative function beyond local short circuits. Because juveniles display no phototaxis until skeleton completion, we suggest a model in which the entire sea urchin, deploying its skeleton as PRC screening device, functions as a huge compound eye.     

Insights into the inhibition of platelet activation by omega-3 polyunsaturated fatty acids: beyond aspirin and clopidogrel

Objectives

We sought to examine the effects of escalating doses of omega-3 polyunsaturated fatty acid (PUFA) supplements on platelet function using light transmission aggregometry (LTA) and electrophoretic quasi-elastic light scattering technology (EQELS).

Background

PUFA may inhibit platelet function through fatty acid substitution in the platelet membrane by changing the surface charge density and causing decreased production of thromboxane A2. EQELS can measure platelet surface charge density and determine whether the platelet is in resting or activated state.

Methods

A total of 30volunteers were divided in 3 groups of 10 as follows: Group A, no antiplatelet agent; Group B, daily aspirin only, and Group C, daily aspirin and clopidogrel. All patients received escalating doses of omega-3PUFA from 1 to 8 g daily over 24 weeks. Platelet function was measured by template bleeding time, LTA, and EQELS at baseline and at 6, 12, 18 and 24 weeks.

Results

Mean bleeding time increased in a dose-dependent manner with escalating omega-3 PUFA doses. LTA confirmed expected antiplatelet effects of aspirin and clopidogrel, but did not detect any additional antiplatelet effects of omega-3 PUFA. EQELS showed a significant increase in the negative resting platelet charge compared to baseline and an attenuated response to arachidonic acid mediated platelet activation. No bleeding events were observed.

Conclusions

In this pilot study we were able to successfully measure platelet surface charge variation as a measure of omega-3 PUFA effect on platelets. Our results suggest that omega-3 PUFA increase the total platelet surface charge and, therefore, attenuate platelet activation, even among patients taking aspirin or aspirin plus clopidogrel. Further studies are needed to determine the clinical significance of these measured effects and EQELS results.     

The need for a new animal model for chronic rejection after lung transplantation

The single most important cause of late mortality after lung transplantation is obliterative bronchiolitis (OB), clinically characterized by a decrease in lung function and morphologically by characteristic changes. Recently, new insights into its pathogenesis have been acquired: risk factors have been identified and the use of azithromycin showed a dichotomy with at least 2 different phenotypes of bronchiolitis obliterans syndrome (BOS). It is clear that a good animal model is indispensable to further dissect and unravel the pathogenesis of BOS. Many animal models have been developed to study BOS but, so far, none of these models truly mimics the human situation. Looking at the definition of BOS, a good animal model implies histological OB lesions, possibility to measure lung function, and airway inflammation. This review sought to discuss, including pros and cons, all potential animal models that have been developed to study OB/BOS. It has become clear that a new animal model is needed; recent developments using an orthotopic mouse lung transplantation model may offer the answer because it mimics the human situation. The genetic variants among this species may open new perspectives for research into the pathogenesis of OB/BOS.     

Guanylate-binding proteins: niche recruiters for antimicrobial effectors

There are fundamental questions regarding how IFN-γ activates host cells to eliminate intracellular pathogens. In this issue of Immunity, Yamamoto et?al. (2012) demonstrate a critical role for the p65 guanylate-binding proteins (GBPs) in this process during infection with Toxoplasma gondii.     

Device-guided breathing exercises for the treatment of hypertension: An overview

The American Heart Association considers device-guided breathing as a reasonable treatment modality in their statement on non-pharmacological options for lowering blood pressure. This review discusses all randomized controlled trials that have investigated the effects of device-guided breathing on blood pressure in patients with hypertension. Thirteen studies were included in this review. In total, 627 patients were in-cluded, of which 365 patients were allocated to device-guided breathing. Only 6 studies used acceptable control groups: listening to music, meditative relaxa-tion exercises, or a sham-device. Two sponsored trials showed beneficial effects of device-guided breathing, both used listening to music as a control group. The remaining 4 studies, which had no employees of the manufacturer listed as co-author, observed no benefi-cial effects on blood pressure. There is only 1 study that used a sham device as a control group. All other studies were to some extend methodologically flawed. Based on the studies with an acceptable methodologi-cal quality, there is no clear evidence supporting a short-term beneficial effect on blood pressure by using device-guided breathing.