Search for: All records

Abstract Tick bites, associated with the secretion of tick saliva containing the xenoglycan galactose-alpha-1, 3-galactose (alpha-gal or aGal), are recognized as the causal factors of alpha-Gal syndrome (AGS; or red meat allergy) in humans. AGS occurs after the increased production of IgE antibodies against aGal, which is found in most mammalian cells, except for the Old World monkey and humans. The aGal sensitization event has been linked to an initial tick bite, followed by consumption of red meat containing the aGal glycan, which triggers the onset of the allergic response resulting in urticaria, anaphylaxis, or even death. In North America, the lone star tick,Amblyomma americanum, has been identified as the main culprit for AGS. However, only a subset of the human population exposed to lone star tick bites develops AGS. This suggests the presence of unidentified variables associated with the sensitization event. To evaluate the quantitative variations of the aGal in ticks, we evaluated the differences in aGal levels in different strains ofA. americanumticks partially fed on different blood sources using an artificial feeding system and animal hosts. We found significantly higher aGal levels in the female ticks fed on human blood than those fed on the blood of other mammals with large variations among different tick populations and individuals. We propose that host-specific genetic components in theA. americanumticks are involved in the production of high aGal epitope in the tick saliva, which provides a part of the explanation for the variables associated with the AGS sensitization event of the tick bite. 

ABSTRACT WR21 and WR31 are two WR + O binaries with short periods, quite similar to the case of V444 Cyg. The XMM-Newton observatory has monitored these two objects and clearly revealed phase-locked variations as expected from colliding winds. The changes are maximum in the soft band (0.5–2.0 keV, variations by a factor 3–4) where they are intrinsically linked to absorption effects. The increase in absorption due to the dense WR wind is confirmed by the spectral analysis. The flux maximum is however not detected exactly at conjunction with the O star in front but slightly afterwards, suggesting Coriolis deflection of the collision zone as in V444 Cyg. In the hard band (2–10 keV), the variations (by a factor of 1.5–2.0) are much more limited. Because of the lower orbital inclinations, eclipses as observed for V444 Cyg are not detected in these systems. 

Massive Wolf-Rayet (WR) stars in binary systems may produce supernovae capable of emitting long-duration gamma-ray bursts (LGRB). The canonical WR+O eclipsing binary is V444 Cygni, which is a WN5+O system that has X-ray emitting colliding winds and a well-constrained geometry. I will present new time-dependent spectropolarimetric data, collected using RSS at the Southern African Large Telescope, from several southern WN+O binary systems that may be analogs to V444 Cygni. By analyzing their polarimetric variations with respect to V444 Cygni, I investigate their wind geometries and assess the similarities among the WN subclass. Characterizing the mass loss and transfer structures within these systems will help to constrain the future evolution of these WN stars and their roles as LGRB prognitors 

https://nexsci.caltech.edu/workshop/2019/ 

Abstract Chemical analysis of calcified structures continues to flourish, as analytical and technological advances enable researchers to tap into trace elements and isotopes taken up in otoliths and other archival tissues at ever greater resolution. Increasingly, these tracers are applied to refine age estimation and interpretation, and to chronicle responses to environmental stressors, linking these to ecological, physiological, and life-history processes. Here, we review emerging approaches and innovative research directions in otolith chemistry, as well as in the chemistry of other archival tissues, outlining their value for fisheries and ecosystem-based management, turning the spotlight on areas where such biomarkers can support decision making. We summarise recent milestones and the challenges that lie ahead to using otoliths and archival tissues as biomarkers, grouped into seven, rapidly expanding and application-oriented research areas that apply chemical analysis in a variety of contexts, namely: (1) supporting fish age estimation; (2) evaluating environmental stress, ecophysiology and individual performance; (3) confirming seafood provenance; (4) resolving connectivity and movement pathways; (5) characterising food webs and trophic interactions; (6) reconstructing reproductive life histories; and (7) tracing stock enhancement efforts. Emerging research directions that apply hard part chemistry to combat seafood fraud, quantify past food webs, as well as to reconcile growth, movement, thermal, metabolic, stress and reproductive life-histories provide opportunities to examine how harvesting and global change impact fish health and fisheries productivity. Ultimately, improved appreciation of the many practical benefits of archival tissue chemistry to fisheries and ecosystem-based management will support their increased implementation into routine monitoring. Graphical abstract