Effects of Sphingomyelin Headgroup Size on Interactions with Ceramide

Sphingomyelins (SMs) and ceramides are known to interact favorably in bilayer membranes. Because ceramide lacks a headgroup that could shield its hydrophobic body from unfavorable interactions with water, accommodation of ceramide under the larger phosphocholine headgroup of SM could contribute to their favorable interactions. To elucidate the role of SM headgroup for SM/ceramide interactions, we explored the effects of reducing the size of the phosphocholine headgroup (removing one, two, or three methyls on the choline moiety, or the choline moiety itself). Using differential scanning calorimetry and fluorescence spectroscopy, we found that the size of the SM headgroup had no marked effect on the thermal stability of ordered domains formed by SM analog/palmitoyl ceramide (PCer) interactions. In more complex bilayers composed of a fluid glycerophospholipid, SM analog, and PCer, the thermal stability and molecular order of the laterally segregated gel domains were roughly identical despite variation in SM headgroup size. We suggest that that the association between PCer and SM analogs was stabilized by ceramide’s aversion for disordered phospholipids, by interfacial hydrogen bonding between PCer and the SM analogs, and by attractive van der Waals’ forces between saturated chains of PCer and SM analogs.     

Assessment of Heart Rate Variability Thresholds from Incremental Treadmill Tests in Five Cross-Country Skiing Techniques

The assessment of heart rate variability (HRV) thresholds (HRVTs) as an alternative of Ventilatory thresholds (VTs) is a relatively new approach with increasing popularity which has not been conducted in cross-country (XC) skiing yet. The main purpose of the present study was to assess HRVTs in the five main XC skiing-related techniques, double poling (DP), diagonal striding (DS), Nordic walking (NW), V1 skating (V1), and V2 skating (V2).Ten competitive skiers completed these incremental treadmill tests until exhaustion with a minimum of one to two recovery days in between each test. Ventilatory gases, HRV and poling frequencies were measured. The first HRV threshold (HRVT₁) was assessed using two time-domain analysis methods, and the second HRV threshold (HRVT₂) was assessed using two non-time varying frequency-domain analysis methods. HRVT₁ was assessed by plotting the mean successive difference (MSD) and standard deviation (SD) of normalized R-R intervals to workload. HRVT₁ was assessed by plotting high frequency power (HFP) and the HFP relative to respiratory sinus arrhythmia (HFP_RSA) with workload. HRVTs were named after their methods (HRVT_1-SD; HRVT_1-MSD; HRVT_2-HFP; HRVT_2-HFP-RSA). The results showed that the only cases where the proposed HRVTs were good assessors of VTs were the HRVT_1-SD of the DS test, the HRVT_1-MSD of the DS and V2 tests, and the HRVT_2-HFP-RSA of the NW test. The lack of a wider success of the assessment of HRVTs was reasoned to be mostly due to the high entrainment between the breathing and poling frequencies. As secondary finding, a novel Cardiolocomotor coupling mode was observed in the NW test. This new Cardiolocoomtor coupling mode corresponded to the whole bilateral poling cycle instead of corresponding to each poling action as it was reported to the date by the existing literature.     

Species delimitation in the European species of Clavulina (Cantharellales, Basidiomycota) inferred from phylogenetic analyses of ITS region and morphological data

The identification of the conventionally accepted species of Clavulina (Cantharellales, Basidiomycota) in Europe (Clavulina amethystina, Clavulina cinerea, Clavulina cristata, and Clavulina rugosa) is often difficult and many specimens are not straightforwardly assignable to any of those four species, which is why some authors have questioned their identity. In order to assess the status of those species, a morphological examination was combined with the molecular analysis of the ITS region. The same six major clades were obtained in the Bayesian and parsimony phylogenetic analyses, and all six clades were well-supported at least by one of the analyses. Morphological characters, such as the overall branching pattern, the presence and intensity of grey colour, the cristation of the apices, and basidiospore size and shape were to various extents correlated with the phylogenetic signal obtained from the ITS region. The congruence between the molecular analyses and morphology, rather than geographical origin, suggests the existence of several species that can be delimited using a combined phylogenetic and morphological species recognition. The analyses revealed that C. cristata and C. rugosa are well-delimited species. In contrast, more than one taxa could be subsumed under the names C. amethystina and C. cinerea, the taxonomical complexity of which is discussed. The ITS region is proved to be adequate to separate phylogenetic species of Clavulina.     

Tell me how and where you play football and I’ll tell you how much you have to run

The aim of this study was to describe the team accumulated physical response per minute considering only the effective playing time (EPT) attending to different contextual and strategic variables in the Spanish Football First Division (LaLiga Santander). A sample of 2,959 performances was included in the analysis, considering a 4-year period of analysis (from 2016–17 to 2019–20). The physical variables were: total distance covered with (DTminPOS) and without (DTminNOpos) possession of the ball, and distance covered at > 21 km·h^-1 with possession (DT21minPOS) and without (DT21minNOpos). Two contextual variables, i.e. Place (Home/Away) and Score (Lost/Draw/Win), and two strategic variables, i.e. level of effective playing time (LevelETP) and level of possession of the ball (LevelPOS), were analysed. The teams ran more without possession of the ball than with possession; nevertheless, the teams that had less possession of the ball had higher values in the distance covered at > 21 km·h^-1 with possession of the ball and vice versa. Furthermore, the strategic variables also had influence on the physical response (DT and DT21) of the teams,LevelETP and LevelPOS, although with interactive effects: longer playing time, less accumulated distance, and greater possession, greater accumulated distance in the defensive phase, both per min. The findings of this study may offer important practical implications to practitioners in order to assess physical performances of the players in matches, because it is crucial to integrate in the analysis the different contextual and strategic variables where the match has taken place to assess performances of the teams.     

Importance of the Sphingoid Base Length for the Membrane Properties of?Ceramides

The sphingoid bases of sphingolipids, including ceramides, can vary in length from 12 to >20 carbons. To study how such length variation affects the bilayer properties of ceramides, we synthesized ceramides consisting of a C12-, C14-, C16-, C18-, or C20-sphing-4-enin derivative coupled to palmitic acid. The ceramides were studied in mixtures with palmitoyloleoylphosphocholine (POPC) and/or palmitoylsphingomyelin (PSM), and in more complex bilayers also containing cholesterol. The trans-parinaric acid lifetimes showed that 12:1- and 14:1-PCer failed to increase the order of POPC bilayers, whereas 16:1-, 18:1-, and 20:1-PCer induced ordered- or gel-phase formation. Nevertheless, all of the analogs were able to thermally stabilize PSM, and a chain-length-dependent increase in the main phase transition temperature of equimolar PSM/Cer bilayers was revealed by differential scanning calorimetry. Similar thermal stabilization of PSM-rich domains by the ceramides was observed in POPC bilayers with a trans-parinaric acid-quenching assay. A cholestatrienol-quenching assay and sterol partitioning experiments showed that 18:1- and 20:1-PCer formed sterol-excluding gel phases with PSM, reducing the overall bilayer affinity of sterol. The effect of 16:1-PCer on sterol distribution was less dramatic, and no displacement of sterol from the PSM environment was observed with 12:1- and 14:1-PCer. The results are discussed in relation to other structural features that affect the bilayer properties of ceramides.     

<Emphasis Type="Italic">Cryptodiscus muriformis</Emphasis> and <Emphasis Type="Italic">Schizoxylon gilenstamii</Emphasis>, two new species of Stictidaceae (Ascomycota)

Cryptodicus muriformis and Schizoxylon gilenstamii (Stictidaceae, Ostropales, Lecanoromycetes, Ascomycota) are described as new to science from collections made in Europe (Sweden, Austria, Switzerland) and North America (Arizona), based on phylogenetic analyses of three loci. Both species show unique morphological characters that distinguish them from closely related species; Cryptodiscus muriformis, growing on decorticated or sometimes corticated branches of Picea abies and Pseudotsuga menziesii, that resembles C. foveolaris and C. tabularum in the yellowish-orange ascomatal disc, but is clearly distinguished by the muriform ascospores. Schizoxylon gilenstamii grows on dead stems of Globularia vulgaris and has a characteristic unique red-purple pigment in the epithecium and upper part of the excipulum that changes to bluish-green with KOH. We also report for the first time the anamorph of Stictis brunnescens.     

A longitudinal analysis of technical-tactical and physical performance of the teams in the Spanish LaLiga Santander: An eight-season study

The aim of this study was to describe in the way teams played for the last eight seasons (from 2011–12 to 2018–19) in the Spanish Football First Division (Spanish LaLiga Santander), taking into account team match performances (n = 5,518). Ten technical-tactical and physical variables grouped into five dimensions were used: final behaviour (shots and crosses), set piece (corners and fouls), match volume (passes), physical performance (total distance covered) and collective use of the space (team width, team length, team defence height and distance from the goalkeeper to their defence). The main results were that the number of passes and team width showed a stable trend as the seasons passed. Nevertheless, the number of shots, crosses and corners, total distance covered, team length and distance from the goalkeeper to their defence showed a descending trend. The main conclusion was that over the seasons studied, the Spanish LaLiga Santander teams were characterized by an indirect style of play that, being the usual in this league, presented some evolution. The trend in the evolution of the game is that defence is put before attack. The findings of the study may be of interest to professional football staff to know more about the particular way teams play in competition, as well as its evolution, so as to focus on the training process according to the trend that is taking place in the game.