Interaction of Bordetella pertussis adenylate cyclase with CD11b/CD18: Role of toxin acylation and identification of the main integrin interaction domain

Adenylate cyclase toxin (CyaA) is one of the major virulence factors produced by Bordetella pertussis, the whooping cough agent. CyaA belongs to the repeat in toxin protein family and requires a post-translational fatty acylation to form cation-selective channels in target cell membranes and to penetrate into cytosol. We have demonstrated recently that CyaA uses the alphaMbeta2 integrin (CD11b/CD18) as a specific cellular receptor. Here we show that the acylation of CyaA is required for a productive and tight interaction of the toxin with cells expressing CD11b. In addition, we demonstrate that the catalytic domain is not required for binding of CyaA to CD11b and that the main integrin interacting domain of CyaA is located in its glycine/aspartate-rich repeat region. These data decipher, for the first time, the interaction of CyaA with CD11b-positive cells and open new prospects for understanding the interaction of Bordetella pertussis with innate and adaptive immune systems.     

Coronaviral RNA-methyltransferases: function,structure and inhibition

Coronaviral methyltransferases (MTases), nsp10/16 and nsp14, catalyze the last two steps of viral RNA-cap creation that takes place in cytoplasm. This cap is essential for the stability of viral RNA and, most importantly, for the evasion of innate immune system. Non-capped RNA is recognized by innate immunity which leads to its degradation and the activation of antiviral immunity. As a result, both coronaviral MTases are in the center of scientific scrutiny. Recently, X-ray and cryo-EM structures of both enzymes were solved even in complex with other parts of the viral replication complex. High-throughput screening as well as structure-guided inhibitor design have led to the discovery of their potent inhibitors. Here, we critically summarize the tremendous advancement of the coronaviral MTase field since the beginning of COVID pandemic.     

Age structure and growth of<Emphasis Type="Italic"> Dracaena cinnabari</Emphasis> populations on Socotra

Unique Dracaena cinnabari woodlands on Socotra Island—relics of the Mio-Pliocene xerophile-sclerophyllous southern Tethys Flora—were examined in detail, especially with regard to their age structure. Detailed statistical analyses of sets of 50 trees at four localities were performed in order to define a model reflecting relationships between specific growth habit and actual age. The problematic nature of determining the age of an individual tree or specific populations of D. cinnabari is illustrated by three models relating to orders of branching, frequency of fruiting, etc. which allow the actual tree age to be calculated. Based on statistical analyses as well as direct field observations, D. cinnabari populations on Socotra do not regenerate to a great extent and their age structure generally indicates overmaturity. The unique Firmihin D. cinnabari woodland will reach the stage of intensive disintegration within 30–77 years with 95% probability. According to our analysis of dead trees, it is evident that, on average, D. cinnabari in populations at Firmihin dies after reaching 17 orders of peripheral branches.     

Screening of electrophilic compounds yields an aziridinyl peptide as new active-site directed SARS-CoV main protease inhibitor

The coronavirus main protease, M^pro, is considered a major target for drugs suitable to combat coronavirus infections including the severe acute respiratory syndrome (SARS). In this study, comprehensive HPLC- and FRET-substrate-based screenings of various electrophilic compounds were performed to identify potential M^pro inhibitors. The data revealed that the coronaviral main protease is inhibited by aziridine- and oxirane-2-carboxylates. Among the trans-configured aziridine-2,3-dicarboxylates the Gly-Gly-containing peptide 2c was found to be the most potent inhibitor.     

Magellanic Wetlands: More than Moor

Magellanic wetlands in the Patagonian steppe are unique habitats from the point of view of conservation and agriculture. Little is known about their environmental characteristics and plant communities. Our aim was to describe vegetation variability to improve current classifications and reveal environmental factors correlated with vegetation variability in the meadow wetlands (vegas) of southern Chilean Patagonia and Chilean Tierra del Fuego. Five vegetation types resulted from TWINSPAN classification and subsequent interpretation, based on which four new associations were delimited: Magellanic acidic marshes – the Scirpo cernui-Calthetum sagittatae, Magellanic alkaline wet grasslands – the Samolo spathulatae-Azorelletum trifurcatae, Magellanic tall sedge marshes – the Carici maclovianae-Agrostietum stoloniferae, and Magellanic pastures – the Hordeo lechleri-Trifolietum repentis. The fifth vegetation type, saline wetlands, is the rarest and so far the least known community. Magellanic wetland vegetation forms a gradient from short saline marshes to tall graminoid-dominated communities. They reflect a major soil gradient of pH and organic matter content, along with the content of major elements (N, P, K, Fe, Al). Other important factors are ground water regime and grazing intensity.     

A seasonal difference of daily energy expenditure in a free-living subterranean rodent,the silvery mole-rat (Heliophobius argenteocinereus; Bathyergidae)

In seasonal climatic regimes, animals have to deal with changing environmental conditions. It is reasonable to expect that seasonal changes are reflected in animal overall energetics. The relation between daily energy expenditure (DEE) and seasonally variable ecological determinants has been studied in many free-living small mammals; however with inconsistent results. Subterranean mammals, i.e. fossorial (burrowing) mammals which live and forage underground, live in a seasonally and diurnally thermally stable environment and represent a suitable model to test seasonality in DEE in respect to seasonal changes, particularly those in soil characteristics and access to food supply. Both factors are affected by seasonal rainfall and are supposed to fundamentally determine activity of belowground dwellers. These ecological constraints are pronounced in some tropical regions, where two distinct periods, dry and rainy seasons, regularly alternate. To explore how a tropical mammal responds to an abrupt environmental change, we determined DEE, resting metabolic rate (RMR) and sustained metabolic scope (SusMS) in a solitary subterranean rodent, the silvery mole-rat, at the end of dry season and the onset of rainy season. Whereas RMR did not differ between both periods, mole-rats had 1.4 times higher DEE and SusMS after the first heavy rains. These findings suggest that rainfall is an important environmental factor responsible for higher energy expenditure in mole-rats, probably due to increased burrowing activity. SusMS in the silvery mole-rat is comparable to values in other bathyergids and all bathyergid values rank among the lowest SusMS found in endothermic vertebrates.     

Dogs discriminate identical twins

Earlier studies have shown variation among experimental attempts to establish whether human monozygotic twins that are genetically identical also have identical individual scents. In none of the cases were the dogs able to distinguish all the individual scents of monozygotic twins living in the same environment if the scents were presented to them separately. Ten specially trained police German Shepherd dogs of three Czech Republic Police Regional Headquarters were used for scent identification in our study. The dogs were supposed to match scents of two monozygotic pairs (5 and 7 years old) and two dizygotic twin pairs (8 and 13 years old). Scents were collected on cotton squares stored in glass jars. Dog handlers were blind to the experiment details. In each trial (line-up), one scent was used as a starting scent and the dog was then sent to determine if any of the 7 presented glass jars contained a matching scent. Scents of children of similar ages were used as distractors. In the matching procedure, the dogs matched correctly the scent of one twin with the other, as well as two scents collected from every single identical and non-identical twin to prove their efficacy and likewise, the presence of the matching twin scent in any given glass jar. All dogs in all trials distinguished correctly the scents of identical as well as non-identical twins. All dogs similarly matched positively two scents collected from the same individuals. Our findings indicated that specially trained German Shepherd dogs are able to distinguish individual scents of identical twins despite the fact that they live in the same environment, eat the same food and even if the scents are not presented to them simultaneously.     

Effect of different factors on proliferation of antler cells, cultured in vitro

Antlers as a potential model for bone growth and development have become an object of rising interest. To elucidate processes explaining how antler growth is regulated, in vitro cultures have been established. However, until now, there has been no standard method to cultivate antler cells and in vitro results are often opposite to those reported in vivo. In addition, many factors which are often not taken into account under in vitro conditions may play an important role in the development of antler cells. In this study we investigated the effects of the antler growth stage, the male individuality, passaged versus primary cultures and the effect of foetal calf serum concentrations on proliferative potential of mixed antler cell cultures in vitro, derived from regenerating antlers of red deer males (Cervus elaphus). The proliferation potential of antler cells was measured by incorporation of (3)H thymidine. Our results demonstrate that there is no significant effect of the antler growth stage, whereas male individuality and all other examined factors significantly affected antler cell proliferation. Furthermore, our results suggest that primary cultures may better represent in vivo conditions and processes occurring in regenerating antlers. In conclusion, before all main factors affecting antler cell proliferation in vitro will be satisfactorily investigated, results of in vitro studies focused on hormonal regulation of antler growth should be taken with extreme caution.