Open Access

Sturgeons are among the most ancient linages of actinopterygians. At present, many sturgeon species are critically endangered. Surrogate production could be used as an affordable and a time-efficient method for endangered sturgeons. Our study established a method for identifying and isolating type A spermatogonia from different developmental stages of testes using flow cytometric cell sorting (FCM). Flow cytometric analysis of a whole testicular cell suspension showed several well-distinguished cell populations formed according to different values of light scatter parameters. FCM of these different cell populations was performed directly on glass slides for further immunocytochemistry to identify germ cells. Results showed that the cell population in gate P1 on a flow cytometry plot (with high forward scatter and high side scatter parameter values) contains the highest amount of type A spermatogonia. The sorted cell populations were characterized by expression profiles of 10 germ cell specific genes. The result confirmed that setting up for the P1 gate could precisely sort type A spermatogonia in all tested testicular developmental stages. The P2 gate, which was with lower forward scatter and side scatter values mostly, contained type B spermatogonia at a later maturing stage. Moreover, expressions of plzf, dnd, boule, and kitr were significantly higher in type A spermatogonia than in later developed germ cells. In addition, plzf was firstly found as a reliable marker to identify type A spermatogonia, which filled the gap of identification of spermatogonial stem cells in sterlet. It is expected to increase the efficiency of germ stem cell culture and transplantation with plzf identification. Our study thus first addressed a phenotypic characterization of a pure type A spermatogonia population in sterlet. FCM strategy can improve the production of sturgeons with surrogate broodstock and further the analysis of the cellular and molecular mechanisms of sturgeon germ cell development.

ObjectivesTo investigate levels of distress, depression, anxiety, stress and perception of their current study situation during the COVID-19 pandemic among undergraduate dental and medical students.DesignObservational, cross-sectional study including two consecutive surveys (May and July 2020).SettingA large medical school in Germany.ParticipantsAll first year dental and medical students were invited. 132 participating first year students (44 dental, 88 medical) from the first survey and 150 students (50 dental, 100 medical) from the second were included in our analyses.Primary and secondary outcome measuresMental burden (distress thermometer, Patient Health Questionnaire-4, Perceived Stress Scale-4) and self-reported changes in mental health and perception of study situation during the COVID-19 pandemic (self-developed items) were compared. Open-ended questions were analysed by conventional content analyses.ResultsA considerable proportion of students (t1: May 2020: 84.1%; t2: July 2020: 77.3%) reported distress levels above cut-off. In July 2020, dental students reported significantly higher distress scores than medical students (dental: M=7.0, SD=2.3; medical: M=5.7; SD=2.1; p<0.001). More dental than medical students reported mild, moderate and severe levels of anxiety and depression symptoms. The majority stated that their mental health and study motivation had not changed during the pandemic. Logistic regression showed that being a dental student was significantly associated with a higher likelihood for serious worries regarding the study situation during COVID-19 at t1 (OR 4.0; 95% CI 1.1 to 14.2). At t2 higher distress was significantly associated with a higher likelihood for experiencing serious worries (OR 1.8; 95% CI 1.3 to 2.5). Regarding current concerns related to the pandemic, students most frequently reported difficulties with self-regulated learning (15.2%), study-related worries and uncertainty (14.4%), missing feedback of students and lecturers (11.4%) and lack of practical training (9.8%).ConclusionThe results suggest that high mental burden and the lack of practical training among medical and dental students is an increasing problem, with a possibly even higher urgency in dental students. Tailored psychological and educational support offers during and after the COVID-19 pandemic might help them as they progress through (medical and) dental school.

Background/Aims Patients with chronic pancreatitis (CP) have an increased risk of malnutrition, a condition linked to reduced muscle mass and physical performance. We have investigated the risk factors, phenotypic presentation, and health implications associated with malnutrition in CP. Materials and Methods In a multicenter cross-sectional study we recruited patients with confirmed CP and healthy volunteers as a control group. Malnutrition was diagnosed according to the criteria proposed by the Global Leadership Initiative on Malnutrition. We performed detailed examinations of body composition and physical function as well as testing of routine blood parameters and markers of inflammation. Results We included 66 patients [mean (±SD) age: 56.0 (±14.5) years; 51 males] and an equal number of age- and sex-matched controls. Moderate malnutrition was diagnosed in 21% (n = 14) and severe malnutrition in 42% (n = 28) of patients. Besides weight loss malnourished patients showed lower fat and skeletal muscle mass compared to both non-malnourished subjects and healthy controls. Only in severe malnutrition, blood parameters reflected elevated inflammation and reduced muscle reserves. Handgrip strength in patients did not differ by nutritional status but there was a significant correlation (rho = 0.705, p < 0.001) with skeletal muscle mass. Although 20 patients (30%) had pathologically reduced skeletal muscle mass, only two individuals (3%) had sarcopenia with concomitantly reduced handgrip strength. Conclusion Malnutrition is a frequent complication of CP characterized by loss of skeletal muscle mass. As this condition becomes evident only at an advanced stage, regular testing for altered body composition is recommended. Suitable biomarkers and the link between loss of muscle mass and physical function require further investigation. Clinical Trial Registration [https://clinicaltrials.gov/ct2/show/NCT04474743], identifier [NCT04474743].

Gallic acid, protocatechuic acid, catechol, and pyrogallol are only a few examples of industrially relevant aromatics. Today much attention is paid to the development of new microbial factories for the environmentally friendly biosynthesis of industrially relevant chemicals with renewable resources or organic pollutants as the starting material. The non–conventional yeast, Blastobotrys raffinosifermentans, possesses attractive properties for industrial bio-production processes such as thermo- and osmotolerance. An additional advantage is its broad substrate spectrum, with tannins at the forefront. The present study is dedicated to the characterization of catechol-1,2-dioxygenase (Acdo1p) and the analysis of its function in B. raffinosifermentans tannic acid catabolism. Acdo1p is a dimeric protein with higher affinity for catechol (KM = 0.004 ± 0.001 mM, kcat = 15.6 ± 0.4 s–1) than to pyrogallol (KM = 0.1 ± 0.02 mM, kcat = 10.6 ± 0.4 s–1). It is an intradiol dioxygenase and its reaction product with catechol as the substrate is cis,cis-muconic acid. B. raffinosifermentans G1212/YIC102-AYNI1-ACDO1-6H, which expresses the ACDO1 gene under the control of the strong nitrate-inducible AYNI1 promoter, achieved a maximum catechol-1,2-dioxygenase activity of 280.6 U/L and 26.9 U/g of dry cell weight in yeast grown in minimal medium with nitrate as the nitrogen source and 1.5% glucose as the carbon source. In the same medium with glucose as the carbon source, catechol-1,2-dioxygenase activity was not detected for the control strain G1212/YIC102 with ACDO1 expression under the regulation of its respective endogenous promoter. Gene expression analysis showed that ACDO1 is induced by gallic acid and protocatechuic acid. In contrast to the wild-type strain, the B. raffinosifermentans strain with a deletion of the ACDO1 gene was unable to grow on medium supplemented with gallic acid or protocatechuic acid as the sole carbon source. In summary, we propose that due to its substrate specificity, its thermal stability, and its ability to undergo long-term storage without significant loss of activity, B. raffinosifermentans catechol-1,2-dioxygenase (Acdo1p) is a promising enzyme candidate for industrial applications.

Parents, peers, and teachers provide a powerful context for school students’ well-being. However, a detailed and systematic analysis of how parental, peer, and teacher support relate to students’ well-being, measured by the dimensions self-worth, psychological and physical well-being, is still missing. To address this research gap, the following study investigates 733 adolescent German students from grades 7 and 8 (Mage = 13.97, SD = 0.41, 52% girls) with respect to their perceived supportive relationships at home and within the school context. The study considers gender, socioeconomic status, and school form as potential confounders. The results of the structural equation model, analyzed with the statistical software R, indicate that perceived teacher support was positively related to students’ self-worth and physical well-being, while peer support was related to psychological well-being. Students who perceived their parents as supportive reported higher well-being with respect to all three dimensions investigated.