Endosomal vacuoles of the prepupal salivary glands of Drosophila play an essential role in the metabolic reallocation of iron

In the recent past, we demonstrated that a great deal is going on in the salivary glands of Drosophila in the interval after they release their glycoprotein‐rich secretory glue during pupariation. The early‐to‐mid prepupal salivary glands undergo extensive endocytosis with widespread vacuolation of the cytoplasm followed by massive apocrine secretion. Here, we describe additional novel properties of these endosomes. The use of vital pH‐sensitive probes provided confirmatory evidence that these endosomes have acidic contents and that there are two types of endocytosis seen in the prepupal glands. The salivary glands simultaneously generate mildly acidic, small, basally‐derived endosomes and strongly acidic, large and apical endosomes. Staining of the large vacuoles with vital acidic probes is possible only after there is ambipolar fusion of both basal and apical endosomes, since only basally‐derived endosomes can bring fluorescent probes into the vesicular system. We obtained multiple lines of evidence that the small basally‐derived endosomes are chiefly involved in the uptake of dietary Fe³⁺ iron. The fusion of basal endosomes with the larger and strongly acidic apical endosomes appears to facilitate optimal conditions for ferrireductase activity inside the vacuoles to release metabolic Fe²⁺ iron. While iron was not detectable directly due to limited staining sensitivity, we found increasing fluorescence of the glutathione‐sensitive probe CellTracker Blue CMAC in large vacuoles, which appeared to depend on the amount of iron released by ferrireductase. Moreover, heterologous fluorescently‐labeled mammalian iron‐bound transferrin is actively taken up, providing direct evidence for active iron uptake by basal endocytosis. In addition, we serendipitously found that small (basal) endosomes were uniquely recognized by PNA lectin, whereas large (apical) vacuoles bound DBA lectin.     

Kinetics and persistence of cellular and humoral immune responses to SARS‐CoV‐2 vaccine in healthcare workers with or without prior COVID‐19

SARS‐CoV‐2 vaccines are highly efficient against severe forms of the disease, hospitalization and death. Nevertheless, insufficient protection against several circulating viral variants might suggest waning immunity and the need for an additional vaccine dose. We conducted a longitudinal study on the kinetics and persistence of immune responses in healthcare workers vaccinated with two doses of BNT162b2 mRNA vaccine with or without prior SARS‐CoV‐2 infection. No new infections were diagnosed during follow‐up. At 6 months, post‐vaccination or post‐infection, despite a downward trend in the level of anti‐S IgG antibodies, the neutralizing activity does not decrease significantly, remaining higher than 75% (85.14% for subjects with natural infection, 88.82% for vaccinated after prior infection and 78.37% for vaccinated only). In a live‐virus neutralization assay, the highest neutralization titres were present at baseline and at 6 months follow‐up in persons vaccinated after prior infection. Anti‐S IgA levels showed a significant descending trend in vaccinated subjects (p < 0.05) after 14 weeks. Cellular immune responses are present even in vaccinated participants with declining antibody levels (index ratio 1.1–3) or low neutralizing activity (30%–40%) at 6 months, although with lower T‐cell stimulation index (p = 0.046) and IFN‐γ secretion (p = 0.0007) compared to those with preserved humoral responses.     

Comparison of Manual and Automatic (MagNA Pure) Isolation Methods of Total RNA from Adipose Tissue

Aim Comparison of manual and automatic (MagNA Pure) isolation methods of total RNA from adipose tissue with respect to its quality and recovery factor. Material 120 human subcutaneous adipose tissue samples (about 100 mg/sample) were collected from patients during surgical operations. The tissue sample was stabilized in RNAlater (QIAGEN GmbH, Germany). Methods Total RNA was extracted by the following kits: Rneasy Protect Mini, Rneasy Lipid Tissue (QIAGEN GmbH, Germany) and MagNA Pure Compact RNA Isolation (Tissue) for MagNA Pure Compact Instrument (Roche Diagnostics GmbH, Germany). Results The average RNA yields with Rneasy Lipid Tissue kits were about two-fold higher in comparison with the Rneasy Protect Mini kit. When the MagNA Pure Compact System was used, RNA yields from the same sample were more uniform compared with manual systems. It was also more convenient and less time-consuming than the manual approach. No DNA contamination of total RNA samples was detected except for samples isolated by Rneasy Protect Mini Kit. Conclusion Rneasy Lipid Tissue Kit and MagNA Pure Compact RNA Isolation Kit (Tissue) provide RNA samples of high quantity, purity and PCR amplificability. RNA samples are suitable for further processing using methods of molecular biology.     

Phytosociological study of grassland vegetation in North Korea

Grasslands were phytosociologically studied in the lowlands of North Korea. They are represented mainly by Lawns in parks and recreation centres. Two new plant communities were distinguished: the associationDigitario ciliaris-Zoysietum japonicae with many species of the C₄ photosynthetic pathway, growing on open sunny habitats and the associationPlantagini asiaticae-Poetum pratensis consisting mostly of species with the C₃ photosynthetic pathway and growing on half shaded or moist habitats. Real pastures and meadows are very rare in North Korea. They are analogous to the communities described from Japan.     

Antioxidative activity of selected fruits and vegetables

Recent studies have demonstrated that dietary plants are rich source of antioxidants and can contribute to the protection from age-related diseases. The aim of our study was to determine the total antioxidant capacity of extracts from different kinds of fruits and vegetables, and to examine their inhibitory effect on the oxidative damage to proteins in vitro. For determination of antioxidant capacity we used two direct methods. Among the food materials chosen for the present study, blueberries and red beets gave the maximum antioxidant activity. The lowest activity was determined in pears and green beans. Some extracts were more active in one method, while their activity was lower using the other method. To investigate inhibitory effects of fruits and vegetables extracts on the oxidative damage to proteins in vitro, we induced the oxidative damage to plasma proteins by sodium hypochlorite leading to formation of carbonyl compounds detected by spectrophotometric method. All extracts of fruits and vegetables showed inhibitory activity on the oxidative damage to proteins with raspberries and leek as most effective. Results of this study will be useful as an aid for dietary choices to increase antioxidant intake and will allow the investigation of the relation between dietary antioxidants and oxidative stress-induced diseases.     

The PERLA system in the Czech Republic: a multivariate approach for assessing the ecological status of running waters

The assessment of running water quality has a long tradition in the Czech Republic, but in the past it focused on the evaluation of organic pollution using the saprobic system. Considering the modern trends of stream ecological status evaluation in water management a new assessment system named PERLA was developed. The system is a complex of biological methods of ecological status assessment of running waters and connected activities in the Czech Republic. It involves 300 reference sites with respective biotic and abiotic data and a prediction model using a newly developed software HOBENT. The model generally follows the published mathematical principles of RIVPACS and represents the site specific and stressor non-specific approaches. The HOBENT software allows the prediction of the target assemblage of benthic macroinvertebrates for any site based on a set of environmental variables (latitude, longitude, distance from source, altitude, slope, catchment area, and stream order) which characterise the site. The predicted assemblage can be compared with the fauna observed at the same site. The comparison makes it possible to evaluate the extent of disturbance, expressed by index B. The model allows to evaluate spring, summer, and autumn seasonal data of the majority of wadable streams in the Czech Republic. The practical application of the PERLA system has started in 2001.