Echocardiographic assessment and percutaneous closure of multiple atrial septal defects

Percutaneous coronary intervention can be associated with distal embolization of thrombotic material causing myocardial necrosis and infarction. We discuss the role of intravascular imaging to guide the use of a distal protection device by describing the outcome of a young woman presenting with non-ST elevation myocardial infarction. Coronary angiography demonstrated an isolated minor stenosis in the proximal left anterior descending coronary artery with slight haziness beyond the lesion. Intravascular ultrasound confirmed an extensive thrombus overlying a bulky atherosclerotic plaque. A distal filter wire was therefore successfully used to reduce the risk of distal embolization. The use of intravascular ultrasound in patients presenting with acute coronary syndrome may reveal large thrombi that are difficult to image using conventional angiographic techniques. Intravascular ultrasound can therefore be used as a tool to select lesions requiring distal protection.     

Emergence and rapid transmission of SARS-CoV-2 B.1.1.7 in the United States

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Further data on predation by free-ranging Stumptail macaques (Macaca arctoides)

Additional data on systematic and occasional hunting of insects, water snails, reptiles, and birds by free-ranging Stumptails are reported. Adult males participated in hunting and meat-eating. However, the hunt was dominated by the adult females and by dominant individuals. Meat-sharing between mother and offspring, between hunter and close-friends, and piece-dropping types were observed. In general almost all troop members including infants displayed an interest in meat eating. Supported by the Mexican Institute of Anthropology and by the Behavioral Science Foundation of Mexico.     

Angiosperm to Gymnosperm host‐plant switch entails shifts in microbiota of the Welwitschia bug,Probergrothius angolensis (Distant, 1902)

The adaptation of herbivorous insects to new host plants is key to their evolutionary success in diverse environments. Many insects are associated with mutualistic gut bacteria that contribute to the host's nutrition and can thereby facilitate dietary switching in polyphagous insects. However, how gut microbial communities differ between populations of the same species that feed on different host plants remains poorly understood. Most species of Pyrrhocoridae (Hemiptera: Heteroptera) are specialist seed‐feeders on plants in the family Malvaceae, although populations of one species, Probergrothius angolensis, have switched to the very distantly related Welwitschia mirabilis plant in the Namib Desert. We first compared the development and survival of laboratory populations of Pr. angolensis with two other pyrrhocorids on seeds of Welwitschia and found only Pr. angolensis was capable of successfully completing its development. We then collected Pr. angolensis in Namibia from Malvaceae and Welwitschia host plants, respectively, to assess their bacterial and fungal community profiles using high‐throughput amplicon sequencing. Comparison with long‐term laboratory‐reared insects indicated stable associations of Pr. angolensis with core bacteria (Commensalibacter, Enterococcus, Bartonella and Klebsiella), but not with fungi or yeasts. Phylogenetic analyses of core bacteria revealed relationships to other insect‐associated bacteria, but also found new taxa indicating potential host‐specialized nutritional roles. Importantly, the microbial community profiles of bugs feeding on Welwitschia versus Malvaceae revealed stark and consistent differences in the relative abundance of core bacterial taxa that correlate with the host‐plant switch; we were able to reproduce this result through feeding experiments. Thus, a dynamic gut microbiota may provide a means for insect adaptation to new host plants in new environments when food plants are extremely divergent.     

Structural basis for the modulation of plant cytosolic triosephosphate isomerase activity by mimicry of redox‐based modifications

Reactive oxidative species (ROS) and S‐glutathionylation modulate the activity of plant cytosolic triosephosphate isomerases (cTPI). Arabidopsis thaliana cTPI (AtcTPI) is subject of redox regulation at two reactive cysteines that function as thiol switches. Here we investigate the role of these residues, AtcTPI‐Cys13 and At‐Cys218, by substituting them with aspartic acid that mimics the irreversible oxidation of cysteine to sulfinic acid and with amino acids that mimic thiol conjugation. Crystallographic studies show that mimicking AtcTPI‐Cys13 oxidation promotes the formation of inactive monomers by reposition residue Phe75 of the neighboring subunit, into a conformation that destabilizes the dimer interface. Mutations in residue AtcTPI‐Cys218 to Asp, Lys, or Tyr generate TPI variants with a decreased enzymatic activity by creating structural modifications in two loops (loop 7 and loop 6) whose integrity is necessary to assemble the active site. In contrast with mutations in residue AtcTPI‐Cys13, mutations in AtcTPI‐Cys218 do not alter the dimeric nature of AtcTPI. Therefore, modifications of residues AtcTPI‐Cys13 and AtcTPI‐Cys218 modulate AtcTPI activity by inducing the formation of inactive monomers and by altering the active site of the dimeric enzyme, respectively. The identity of residue AtcTPI‐Cys218 is conserved in the majority of plant cytosolic TPIs, this conservation and its solvent‐exposed localization make it the most probable target for TPI regulation upon oxidative damage by reactive oxygen species. Our data reveal the structural mechanisms by which S‐glutathionylation protects AtcTPI from irreversible chemical modifications and re‐routes carbon metabolism to the pentose phosphate pathway to decrease oxidative stress.     

Genetic and ultrastructural analysis of different mutants of Pseudomonas putida affected in the poly-3-hydroxy-n-alkanoate gene cluster

Functional analyses of the different proteins involved in the synthesis and accumulation of polyhydroxyalkanoates (PHAs) in P. putida U were performed using a mutant in which the pha locus had been deleted (PpUDeltapha). These studies showed that: (i) Pha enzymes cannot be replaced by other proteins in this bacterium, (ii) the transformation of PpDeltapha with a plasmid containing the locus pha fully restores the synthesis of bioplastics, (iii) the transformation of PpDeltapha with a plasmid harbouring the gene encoding the polymerase PhaC1 (pMCphaC1) permits the synthesis of polyesters (even in absence of phaC2ZDFI); however, in this strain (PpUDeltapha-pMCphaC1) the number of PHAs granules was higher than in the wild type, (iv) the expression of phaF in PpUDeltapha-pMCphaC1 restores the original phenotype, showing that PhaF is involved in the coalescence of the PHAs granules. Furthermore, the deletion of the phaDFI genes in P. putida U considerably decreases (> 70%) the biosynthesis of PHAs consisting of hydroxyalkanoates with aliphatic constituents, and completely prevents the synthesis of those ones containing aromatic monomers. Additional experiments revealed that the deletion of phaD in P. putida U strongly reduces the synthesis of PHA, this effect being restored by PhaF. Moreover, the overexpression of phaF in P. putida U, or in its DeltafadBA mutant, led to the collection of PHA over-producer strains.     

Real-time studies of the progression of bacterial infections and immediate tissue responses in live animals

By combining intravital multiphoton microscopy and bacterial genetics we have developed a technique enabling real-time imaging of bacterial proliferation and tissue responses in a live animal. Spatial and temporal control of the infection process was achieved by microinjecting GFP(+)-expressing uropathogenic Escherichia coli (UPEC) into tubules of exteriorized kidneys in live rats. GFP(+) was introduced in the clinical UPEC strain CFT073 as a single-copy chromosomal gene fusion. Within hours, bacterial colonization was accompanied by marked ischaemic effects, perivascular leakage, loss of tubular integrity and localized recruitment of immune cells. The pathophysiology was altered in response to an isogenic bacterial strain lacking the exotoxin haemolysin, revealing the subtle and temporal roles of bacterial virulence factors in vivo. Microdissection and RNA extraction of the injected nephron allowed molecular analysis of prokaryotic and eukaryotic gene expression. The techniques described here can be applied to study the integrated cell communication evoked by a variety of bacterial pathogens, assisting in the design of strategies to combat bacterial infections.     

The hisC1 gene, encoding aromatic amino acid aminotransferase-1 in Azospirillum brasilense Sp7, expressed in wheat

Background and aims

Production of indole-3-acetic acid (IAA) by Azospirillum brasilense is one of the most important mechanisms underlying the beneficial effects observed in plants after inoculation with this bacterium. This study determined the contribution of the hisC1 gene, which encodes aromatic amino acid aminotransferase-1 (AAT1), to IAA production, and analyzed its expression in the free-living state and in association with the roots of wheat.

Methods

We determined production of IAA and AAT activity in the mutant hisC::gusA-sm ^R . To study the expression of hisC1, a chromosomal gene fusion was analyzed by following β-glucuronidase (GUS) activity in vitro, in the presence of root exudates, and in association with roots.

Results

IAA production in the hisC mutant was not reduced significantly compared to the activity of the wild-type strain. AAT1 activity was reduced by 50% when tyrosine was used as the amino acid donor, whereas there was a 30% reduction when tryptophan was used, compared to the activity of the wild-type strain. Expression of the fusion protein was up-regulated in both logarithmic and stationary phases by several compounds, including IAA, tryptophan, tyrosine, and phenyl acetic acid. We observed the expression of hisC1 in bacteria associated with wheat roots. Root exudates of wheat and maize were able to stimulate hisC1 expression.

Conclusions

The expression data indicate that hisC1 is under a positive feedback control in the presence of root exudates and on plants, suggesting that AAT1 activity plays a role in Azospirillum–plant interactions.     

Familial hemiplegic migraine type 1 mutations W1684R and V1696I alter G protein-mediated regulation of CaV2.1 voltage-gated calcium channels

Familial hemiplegic migraine type 1 (FHM-1) is a monogenic form of migraine with aura that is characterized by recurrent attacks of a typical migraine headache with transient hemiparesis during the aura phase. In a subset of patients, additional symptoms such as epilepsy and cerebellar ataxia are part of the clinical phenotype. FHM-1 is caused by missense mutations in the CACNA1A gene that encodes the pore-forming subunit of Ca_V2.1 voltage-gated Ca^2 + channels. Although the functional effects of an increasing number of FHM-1 mutations have been characterized, knowledge on the influence of most of these mutations on G protein regulation of channel function is lacking. Here, we explored the effects of G protein-dependent modulation on mutations W1684R and V1696I which cause FHM-1 with and without cerebellar ataxia, respectively. Both mutations were introduced into the human Ca_V2.1α₁ subunit and their functional consequences investigated after heterologous expression in human embryonic kidney 293 (HEK‐293) cells using patch-clamp recordings. When co-expressed along with the human μ-opioid receptor, application of the agonist [d‐Ala2, N‐MePhe4, Gly‐ol]‐enkephalin (DAMGO) inhibited currents through both wild-type (WT) and mutant Ca_V2.1 channels, which is consistent with the known modulation of these channels by G protein-coupled receptors. Prepulse facilitation, which is a way to characterize the relief of direct voltage-dependent G protein regulation, was reduced by both FHM-1 mutations. Moreover, the kinetic analysis of the onset and decay of facilitation showed that the W1684R and V1696I mutations affect the apparent dissociation and reassociation rates of the Gβγ dimer from the channel complex, suggesting that the G protein-Ca^2 + channel affinity may be altered by the mutations. These biophysical studies may shed new light on the pathophysiology underlying FHM-1.