Genetic Screens Identify Host Factors for SARS-CoV-2 and Common Cold Coronaviruses

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Discovery and functional interrogation of SARS-CoV-2 RNA-host protein interactions

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Profiling of Volatile Organic Compounds in Exhaled Breath As a Strategy to Find Early Predictive Signatures of Asthma in Children

Wheezing is one of the most common respiratory symptoms in preschool children under six years old. Currently, no tests are available that predict at early stage who will develop asthma and who will be a transient wheezer. Diagnostic tests of asthma are reliable in adults but the same tests are difficult to use in children, because they are invasive and require active cooperation of the patient. A non-invasive alternative is needed for children. Volatile Organic Compounds (VOCs) excreted in breath could yield such non-invasive and patient-friendly diagnostic. The aim of this study was to identify VOCs in the breath of preschool children (inclusion at age 2–4 years) that indicate preclinical asthma. For that purpose we analyzed the total array of exhaled VOCs with Gas Chromatography time of flight Mass Spectrometry of 252 children between 2 and 6 years of age. Breath samples were collected at multiple time points of each child. Each breath-o-gram contained between 300 and 500 VOCs; in total 3256 different compounds were identified across all samples. Using two multivariate methods, Random Forests and dissimilarity Partial Least Squares Discriminant Analysis, we were able to select a set of 17 VOCs which discriminated preschool asthmatic children from transient wheezing children. The correct prediction rate was equal to 80% in an independent test set. These VOCs are related to oxidative stress caused by inflammation in the lungs and consequently lipid peroxidation. In conclusion, we showed that VOCs in the exhaled breath predict the subsequent development of asthma which might guide early treatment.     

Sensory Neuron-Derived Eph Regulates Glomerular Arbors and Modulatory Function of a Central Serotonergic Neuron

Olfactory sensory neurons connect to the antennal lobe of the fly to create the primary units for processing odor cues, the glomeruli. Unique amongst antennal-lobe neurons is an identified wide-field serotonergic neuron, the contralaterally-projecting, serotonin-immunoreactive deutocerebral neuron (CSDn). The CSDn spreads its termini all over the contralateral antennal lobe, suggesting a diffuse neuromodulatory role. A closer examination, however, reveals a restricted pattern of the CSDn arborization in some glomeruli. We show that sensory neuron-derived Eph interacts with Ephrin in the CSDn, to regulate these arborizations. Behavioural analysis of animals with altered Eph-ephrin signaling and with consequent arborization defects suggests that neuromodulation requires local glomerular-specific patterning of the CSDn termini. Our results show the importance of developmental regulation of terminal arborization of even the diffuse modulatory neurons to allow them to route sensory-inputs according to the behavioural contexts.     

Temporal variability of top-down forces and their role in host choice evolution of phytophagous arthropods

The role of top-down forces in host choice evolution of phytophagous arthropods is the subject of a vividly animated debate. Empirical evidence for the evolutionary role of top-down forces comes from studies showing that phytophagous arthropods prefer hosts that entail enemy-free space. The aim of this paper is to draw the attention of plant–arthropod researchers to the potentially, temporally variable nature of third trophic level effects. We show that this aspect is largely neglected in studies on enemy-free space, despite the fact that relative enemy impact varies seasonally among plants in at least some studies. We conclude that rigorous testing of the enemy-free space hypothesis can only be performed when within and between season variation in higher trophic level effects is taken into account.     

Low dose effects of chemicals as assessed by the flow cytometric in vivo micronucleus assay

Using flow cytometric automation of the mouse in vivo, micronucleus assay increases the sensitivity of the test. This is achieved through a very large increase in the number of cells scored, by a factor of 100×, which in turn greatly reduces the sampling error. With this method, dose–response relationships of in vivo micronucleus induction for four model agents mitomycin C (MMC), diepoxybutane (DEB), cyclophosphamide (CPA), and colchicine (COL) were studied at low dose levels. For the three clastogens MMC, DEB and CPA, linear dose–response relationships were found over the dose ranges studied, even in the very low dose region (defined as the dose region where the frequency of micronucleated erythrocytes is less than twice the baseline frequency). This is consistent with the view that no threshold should exist for genotoxic agents which target DNA. For COL a dose range was found, in which the frequency of micronucleated erythrocytes did not increase with dose, possibly indicating an in vivo threshold. The flow cytometric in vivo micronucleus assay represents one possibility for in vivo low dose–response studies.     

Courtship herding in the fiddler crab <Emphasis Type="Italic">Uca elegans</Emphasis>

Male and female animals are not always complicit during reproduction, giving rise to coercion. One example of a system that is assumed to involve sexual coercion is the mate herding behaviour of fiddler crabs: males push females towards the home burrow with the goal of forcing copulation at the burrow entrance. We recorded and analysed in detail the courtship behaviour of a North Australian species of fiddler crab Uca elegans. Courtship was composed of four main phases: broadcast waving, outward run, herding and at burrow display. During interactions males produced claw-waving displays which were directed posteriorly towards the female and which varied in timing and structure depending on the courtship phase. We suggest that courtship herding in U. elegans is driven primarily by mate choice for the following reasons, (1) females can evade herding, (2) no other reproductive strategies were observed, (3) males broadcast their presence and accompany courtship with conspicuous claw waves, and (4) the behaviour ends with the female leading the male into the home burrow. As an alternative function for herding in U. elegans we suggest that the behaviour represents a form of courtship guiding, in which males direct complicit females to the correct home burrow.