Repercussions of the COVID-19 pandemic on athletes: a cross-sectional study

The COVID-19 pandemic has presented significant challenges and implications for the sports community. Thus, this study aimed to describe the prevalence of COVID-19 in Brazilian athletes and identify the epidemiological, clinical, athletic, life and health factors associated with the disease in these individuals. A cross-sectional study was performed involving 414 athletes from 22 different sports using an online questionnaire from August to November 2020. The association between the athletes’ characteristics and COVID-19 was evaluated using a logistic regression model. The prevalence of COVID-19 was 8.5%, although only 40% of athletes reported having been tested. Being under 27 years of age (3-fold), having children (~5-fold), having a teammate test positive for COVID-19 (2.5-fold), and smoking (14-fold) were associated with a possible higher risk of disease. Almost 20% of athletes self-reported musculoskeletal injuries during the period of the pandemic that was studied. Athletes with a university education (P = 0.02), a profession other than sports (P < 0.001), those from a low-income family (P = 0.01), and public health system users (P = 0.04) were significantly less frequently tested for COVID-19, whereas international competitors, athletes who received a wage, and athletes who had a teammate who tested positive for COVID-19 were 2-, 3-, and 15-fold more likely to be tested for COVID-19, respectively. Approximately 26% of the athletes who tested negative or were untested reported more than three characteristic COVID-19 symptoms, and 11% of athletes who tested positive for COVID-19 were asymptomatic. The identification of modifiable (have children, smoking, and teammates positively tested) and non-modifiable (age under 27 years) factors related to COVID-19 in athletes can contribute to implementing surveillance programmes to decrease the incidence of COVID-19 in athletes and its negative impacts in sports.     

Complete genome sequence of Mahella australiensis type strain (50-1 BON)

Mahella australiensis Bonilla Salinas et al. 2004 is the type species of the genus Mahella, which belongs to the family Thermoanaerobacteraceae. The species is of interest because it differs from other known anaerobic spore-forming bacteria in its G+C content, and in certain phenotypic traits, such as carbon source utilization and relationship to temperature. Moreover, it has been discussed that this species might be an indigenous member of petroleum and oil reservoirs. This is the first completed genome sequence of a member of the genus Mahella and the ninth completed type strain genome sequence from the family Thermoanaerobacteraceae. The 3,135,972 bp long genome with its 2,974 protein-coding and 59 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Molluscan catch muscle myorod and its N-terminal peptide bind to F-actin and myosin in a phosphorylation-dependent manner

Myorod is expressed exclusively in molluscan catch muscle and localizes on the surface of thick filaments together with twitchin and myosin. This protein is an alternatively spliced product of the myosin heavy-chain gene containing the C-terminal rod part of myosin and a unique N-terminal domain. We have recently reported that this unique domain is a target for phosphorylation by gizzard smooth muscle myosin light chain kinase (MLCK) and molluscan twitchin, which contains a MLCK-like domain. To elucidate the role of myorod phosphorylation in catch muscle, a peptide corresponding to the specific N-terminal region of the protein was synthesized in phosphorylated and unphosphorylated form. We report, for the first time, that unphosphorylated full-length myorod and its unphosphorylated N-terminal synthetic peptide are able to interact with rabbit F-actin and thin filaments from molluscan catch muscle. The binding between thin filaments and the peptide was Ca²⁺-dependent. In addition, we found that phosphorylated N-terminal peptide of myorod has higher affinity for myosin compared to the unphosphorylated peptide. Together, these observations suggest the direct involvement of the N-terminal domain of myorod in the regulation of molluscan catch muscle.     

Some effects of repeated handling and the use of a mask on stress responses in zebu cattle during restraint

The objective of this investigation was to evaluate the effect of repeated handling and the use of a mask on the order of entry, temperament, cortisol concentration and heart and respiratory rates of Brahman cattle during restraint in a squeeze chute. In the first experiment, 18 cows were restrained in the chute for 10min on 19 test-days and blood samples were collected during five of the trials. Habituation to handling was reflected by a decrease in cortisol concentration as the study advanced (P<0.01). In the second experiment, conducted 6 months later, animals were randomly allotted to two groups, alternating the use of a mask over test-days while restraining the cows in the chute for 3min. Respiratory and heart rates were measured at the beginning and end of each 3min trial. A blood sample was also taken at the end of each trial. Respiratory rates decreased while the animals were restrained and this decrease tended to be greater (P=0.09) when the animals were wearing masks (3.06) than when not (2.2breaths/min). Heart rates also decreased and more so for masked animals (10.6beats/min) than for non-masked (5.0, P<0.01). Cortisol values tended to be higher (9.9 versus 4.7ng/ml, P=0.08) when animals were restrained without a mask. Temperament scores were lower (P>0.01) when cows were masked and have a relative high correlation (r=0.58) with flight distance values, (P<0.05). Finally, the order of entrance was found consistent over test-days, (P<0.01). It is concluded that Brahman cattle: (a) habituate to repeat handling in a squeeze chute; (b) are less emotionally reactive when their eyes were covered during this process and (c) establish a repeatable order of entrance to the chute.     

The Influence of Changes in Magnetic Variations and Light–Dark Cycle on Life-History Traits of Daphnia magna

Day–night cycle is the main zeitgeber (time giver) for biological circadian rhythms. Recently, it was suggested that natural diurnal geomagnetic variation may also be utilized by organisms for the synchronization of these rhythms. In this study, life-history traits in Daphnia magna were evaluated after short-term and multigenerational exposure to 16 h day/8 h night cycle, 32 h day/16 h night cycle, diurnal geomagnetic variation of 24 h, simulated magnetic variation of 48 h, and combinations of these conditions. With short-term exposure, the lighting mode substantially influenced the brood to brood period and the lifespan in daphnids. The brood to brood period, brood size, and body length of crustaceans similarly depended on the lighting mode during the multigenerational exposure. At the same time, an interaction of lighting mode and magnetic variations affected to a lesser extent brood to brood period, brood size, and newborn's body length. The influence of simulated diurnal variation on life-history traits in daphnids appeared distinctly as effects of synchronization between periods of lighting mode and magnetic variations during the multigenerational exposure. Newborn's body length significantly depended on the lighting regime when the periods of both studied zeitgebers were unsynchronized, or on the interaction of light regime with magnetic variations when the periods were synchronized. These results confirm the hypothesis that diurnal geomagnetic variation is an additional zeitgeber for biological circadian rhythms. Possible mechanisms for these observed effects are discussed. Bioelectromagnetics. © 2020 Bioelectromagnetics Society     

Chlorophyll fluorescence induction and relaxation system for the continuous monitoring of photosynthetic capacity in photobioreactors

The development of high‐performance photobioreactors equipped with automatic systems for non‐invasive real‐time monitoring of cultivation conditions and photosynthetic parameters is a challenge in algae biotechnology. Therefore, we developed a chlorophyll (Chl) fluorescence measuring system for the online recording of the light‐induced fluorescence rise and the dark relaxation of the flash‐induced fluorescence yield (Qa^? ? re‐oxidation kinetics) in photobioreactors. This system provides automatic measurements in a broad range of Chl concentrations at high frequency of gas‐tight sampling, and advanced data analysis. The performance of this new technique was tested on the green microalgae Chlamydomonas reinhardtii subjected to a sulfur deficiency stress and to long‐term dark anaerobic conditions. More than thousand fluorescence kinetic curves were recorded and analyzed during aerobic and anaerobic stages of incubation. Lifetime and amplitude values of kinetic components were determined, and their dynamics plotted on heatmaps. Out of these data, stress‐sensitive kinetic parameters were specified. This implemented apparatus can therefore be useful for the continuous real‐time monitoring of algal photosynthesis in photobioreactors.     

Crystal structure of the YjeE protein from Haemophilus influenzae: a putative Atpase involved in cell wall synthesis

A hypothetical protein encoded by the gene YjeE of Haemophilus influenzae was selected as part of a structural genomics project for X-ray analysis to assist with the functional assignment. The protein is considered essential to bacteria because the gene is present in virtually all bacterial genomes but not in those of archaea or eukaryotes. The amino acid sequence shows no homology to other proteins except for the presence of the Walker A motif G-X-X-X-X-G-K-T that indicates the possibility of a nucleotide-binding protein. The YjeE protein was cloned, expressed, and the crystal structure determined by the MAD method at 1.7-A resolution. The protein has a nucleotide-binding fold with a four-stranded parallel beta-sheet flanked by antiparallel beta-strands on each side. The topology of the beta-sheet is unique among P-loop proteins and has features of different families of enzymes. Crystallization of YjeE in the presence of ATP and Mg2+ resulted in the structure with ADP bound in the P-loop. The ATPase activity of YjeE was confirmed by kinetic measurements. The distribution of conserved residues suggests that the protein may work as a "molecular switch" triggered by ATP hydrolysis. The phylogenetic pattern of YjeE suggests its involvement in cell wall biosynthesis.     

In vitro maturation and early developmental capacity of bovine oocytes cultured in pure follicular fluid and supplementation with follicular wall

Mammalian oocytes mature in follicular fluid (FF), surrounded by follicular cells. In the present study, in vitro maturation of bovine oocytes cultured in FF from dominant follicles 15-17mm in diameter (with various forms of heat pretreatment) and supplementation with follicular wall from follicles 3-5mm in diameter (FW1) were examined. Heat pretreatment of FF was as follows: (1) no treatment (FF1); (2) 56 degrees C for 30min (FF2); and (3) 100 degrees C for 20s (FF3). After IVM in FF1, oocytes underwent IVF and IVC and embryo development was assessed (up to the morula stage). The rate of oocyte maturation was decreased in pure FF1 versus control (44.5% versus 62.8%, P<0.001). In the control medium, FW1 did not significantly affect nuclear maturation. By contrast, the addition of FW1 to FF1 increased the rate of matured oocytes approximately two-fold (85.9% versus 45.6%, P<0.001). Furthermore, the maturation rate in the FF+FW1 system declined (from 85.9 to 71.0%, P<0.001), whereas that in the FF system increased (from 45.6 to 71.6%, P<0.001) with increased temperature of the FF treatment. Supplementation of the control medium with FW1 increased the yield of morulae (42.6% versus 13.7%, P<0.001). However, the stimulatory effect of FW1 on the morula rate was much higher in pure FF1 (72.5% versus 31.7%, P<0.001). These findings indicated, for the first time, the stimulatory impact of FW1 on in vitro maturation and early developmental capacity of bovine oocytes cultured in pure FF from dominant follicles. We also inferred that bovine FF constituents affecting bovine oocyte maturation and the meiosis-promoting ability of the FW were heat-labile.     

Mast cells promote atherosclerosis by releasing proinflammatory cytokines

Mast cells contribute importantly to allergic and innate immune responses by releasing various preformed and newly synthesized mediators. Previous studies have shown mast cell accumulation in human atherosclerotic lesions. This report establishes the direct participation of mast cells in atherogenesis in low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice. Atheromata from compound mutant Ldlr(-/-) Kit(W-sh)(/W-sh) mice showed decreased lesion size, lipid deposition, T-cell and macrophage numbers, cell proliferation and apoptosis, but increased collagen content and fibrous cap development. In vivo, adoptive transfer of syngeneic wild-type or tumor necrosis factor (TNF)-alpha-deficient mast cells restored atherogenesis to Ldlr(-/-)Kit(W-sh/W-sh) mice. Notably, neither interleukin (IL)-6- nor interferon (IFN)-gamma-deficient mast cells did so, indicating that the inhibition of atherogenesis in Ldlr(-/-)Kit(W-sh/W-sh) mice resulted from the absence of mast cells and mast cell-derived IL-6 and IFN-gamma. Compared with wild-type or TNF-alpha-deficient mast cells, those lacking IL-6 or IFN-gamma did not induce expression of proatherogenic cysteine proteinase cathepsins from vascular cells in vitro or affect cathepsin and matrix metalloproteinase activities in atherosclerotic lesions, implying that mast cell-derived IL-6 and IFN-gamma promote atherogenesis by augmenting the expression of matrix-degrading proteases. These observations establish direct participation of mast cells and mast cell-derived IL-6 and IFN-gamma in mouse atherogenesis and provide new mechanistic insight into the pathogenesis of this common disease.