Contrasting phylogenetic patterns of anther smuts (Pucciniomycotina: Microbotryum) reflect phylogenetic patterns of their caryophyllaceous hosts

Anther smuts in the genus Microbotryum often show very high host specificity toward their caryophyllaceous hosts, but some of the larger host groups such as Dianthus are crucially undersampled for these parasites so that the question of host specificity cannot be answered conclusively. In this study we sequenced the internal transcribed spacer (ITS) region of members of the Microbotryum dianthorum species complex as well as their Dianthus hosts. We compared phylogenetic trees of these parasites including sequences of anther smuts from other Caryophyllaceae, mainly Silene, with phylogenies of Caryophyllaceae that are known to harbor anther smuts. Additionally we tested whether observed patterns in parasites are due to shared ancestry or if geographic separation is a factor that should be taken into consideration in delimitating species. Parasites on Dianthus showed mainly an arbitrary distribution on Dianthus hosts, whereas parasites on other Caryophyllaceae formed well-supported monophyletic clades that corresponded to restricted host groups. The same pattern was observed in the Caryophyllaceae studied: morphologically described Dianthus species did not correspond well with monophyletic clades based on molecular data, whereas other Caryophyllaceae mainly did. We suggest that these different patterns primarily result from different breeding systems and speciation times between different host groups as well as difficulties in species delimitations in the genus Dianthus.     

Quantification of optic disc edema during exposure to high altitude shows no correlation to acute mountain sickness

Background

The study aimed to quantify changes of the optic nerve head (ONH) during exposure to high altitude and to assess a correlation with acute mountain sickness (AMS). This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study.

Methodology/Principal Findings

A confocal scanning laser ophthalmoscope (cSLO, Heidelberg Retina Tomograph, HRT3®) was used to quantify changes at the ONH in 18 healthy participants before, during and after rapid ascent to high altitude (4559 m). Slitlamp biomicroscopy was used for clinical optic disc evaluation; AMS was assessed with Lake Louise (LL) and AMS-cerebral (AMS-c) scores; oxygen saturation (SpO₂) and heart rate (HR) were monitored. These parameters were used to correlate with changes at the ONH. After the first night spent at high altitude, incidence of AMS was 55% and presence of clinical optic disc edema (ODE) 79%. Key stereometric parameters of the HRT3® used to describe ODE (mean retinal nerve fiber layer [RNFL] thickness, RNFL cross sectional area, optic disc rim volume and maximum contour elevation) changed significantly at high altitude compared to baseline (p<0.05) and were consistent with clinically described ODE. All changes were reversible in all participants after descent. There was no significant correlation between parameters of ODE and AMS, SpO₂ or HR.

Conclusions/Significance

Exposure to high altitude leads to reversible ODE in the majority of healthy subjects. However, these changes did not correlate with AMS or basic physiologic parameters such as SpO₂ and HR. For the first time, a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure. In conclusion, ODE presents a reaction of the body to high altitude exposure unrelated to AMS.     

Gaze Holding in Healthy Subjects

Eccentric gaze in darkness evokes minor centripetal eye drifts in healthy subjects, as cerebellar control sufficiently compensates for the inherent deficiencies of the brainstem gaze-holding network. This behavior is commonly described using a leaky integrator model, which assumes that eye velocity grows linearly with gaze eccentricity. Results from previous studies in patients and healthy subjects suggest caution when this assumption is applied to eye eccentricities larger than 20 degrees. To obtain a detailed characterization of the centripetal gaze-evoked drift, we recorded horizontal eye position in 20 healthy subjects. With their head fixed, they were asked to fixate a flashing dot (50 ms every 2 s)that was quasi-stationary displacing(0.5 deg/s) between ±40 deg horizontally in otherwise complete darkness. Drift velocity was weak at all angles tested. Linearity was assessed by dividing the range of gaze eccentricity in four bins of 20 deg each, and comparing the slopes of a linear function fitted to the horizontal velocity in each bin. The slopes of single subjects for gaze eccentricities of ±0−20 deg were, in median,0.41 times the slopes obtained for gaze eccentricities of ±20−40 deg. By smoothing the individual subjects'' eye velocity as a function of gaze eccentricity, we derived a population of position-velocity curves. We show that a tangent function provides a better fit to the mean of these curves when large eccentricities are considered. This implies that the quasi-linear behavior within the typical ocular motor range is the result of a tuning procedure, which is optimized in the most commonly used range of gaze. We hypothesize that the observed non-linearity at eccentric gaze results from a saturation of the input that each neuron in the integrating network receives from the others. As a consequence, gaze-holding performance declines more rapidly at large eccentricities.     

Sec14 family of lipid transfer proteins in yeasts

The hydrophobicity of lipids prevents their free movement across the cytoplasm. To achieve highly heterogeneous and precisely regulated lipid distribution in different cellular membranes, lipids are transported by lipid transfer proteins (LTPs) in addition to their transport by vesicles. Sec14 family is one of the most extensively studied groups of LTPs. Here we provide an overview of Sec14 family of LTPs in the most studied yeast Saccharomyces cerevisiae as well as in other selected non-Saccharomyces yeasts—Schizosaccharomyces pombe, Kluyveromyces lactis, Candida albicans, Candida glabrata, Cryptococcus neoformans, and Yarrowia lipolytica. Discussed are specificities of Sec14-domain LTPs in various yeasts, their mode of action, subcellular localization, and physiological function. In addition, quite few Sec14 family LTPs are target of antifungal drugs, serve as modifiers of drug resistance or influence virulence of pathologic yeasts. Thus, they represent an important object of study from the perspective of human health.     

Abstracts from the 3rd Annual A-CURE Symposium

Background

Patients after aortic coarctation (CoA) repair show impaired aortic bioelasticity and altered left ventricular (LV) mechanics, predisposing diastolic dysfunction. Our purpose was to assess aortic bioelasticity and LV properties in CoA patients who underwent endovascular stenting or surgery using cardiovascular magnetic resonance (CMR) imaging.

Methods

Fifty CoA patients (20.5 ± 9.5 years) were examined by 3-Tesla CMR. Eighteen patients had previous stent implantation and 32 had surgical repair. We performed volumetric analysis of both ventricles (LV, RV) and left atrium (LA) to measure biventricular volumes, ejection fractions, left atrial (LA) volumes, and functional parameters (LAEF_Passive, LAEF_Contractile, LAEF_Reservoir). Aortic distensibility and pulse wave velocity (PWV) were assessed. Native T1 mapping was applied to examine LV tissue properties. In twelve patients post-contrast T1 mapping was performed.

Results

LV, RV and LA parameters did not differ between the surgical and stent group. There was also no significant difference for aortic distensibility, PWV and T1 relaxation times. Aortic root distensibility correlated negatively with age, BMI, BSA and weight (p < 0.001). Native T1 values correlated negatively with age, weight, BSA and BMI (p < 0.001). Lower post-contrast T1 values were associated with lower aortic arch distensibility and higher aortic arch PWV (p < 0.001).

Conclusions

CoA patients after surgery or stent implantation did not show significant difference of aortic elasticity. Thus, presumably other factors like intrinsic aortic abnormalities might have a greater impact on aortic elasticity than the approach of repair. Interestingly, our data suggest that native T1 values are influenced by demographic characteristics.