Six new non-native ants (Formicidae) in the Canary Islands and their possible impacts

Biological invasions are one of the main causes of biodiversity loss, especially on oceanic islands. Ants are among the most damaging pests in the world. After systematic sampling of more than 1,000 localities in the Canary Islands, six new exotic ant species are reported for the first time: Pheidole bilimeki (Myrmicinae), Pheidole navigans (Myrmicinae), Strumigenys membranifera (Myrmicinae), Brachymyrmex cordemoyi (Formicinae), Tapinoma darioi (Dolichoderinae) and Technomyrmex pallipes (Dolichoderinae). Moreover, another two recently reported species have been genetically confirmed. Morphological and genetic data were analysed to confirm the identity of the new records. For each species, information regarding identification, distribution, global invasive records and possible impacts is given. The arrival of these species may endanger local biodiversity.     

Structural determinants stabilizing the axial channel of ClpP for substrate translocation

Acyldepsipeptides (ADEPs) antibiotics bind to Escherichia coli ClpP mimicking the interactions that the IGL/F loops in ClpA or ClpX ATPases establish with the hydrophobic pockets surrounding the axial pore of the tetradecamer that the protease forms. ADEP binding induces opening of the gates blocking the axial channel of ClpP and allowing protein substrates to be translocated and hydrolysed in the degradation chamber. To identify the structural determinants stabilizing the open conformation of the axial channel for efficient substrate translocation, we constructed ClpP variants with amino acid substitutions in the N‐terminal region that forms the axial gates. We found that adoption of a β‐hairpin loop by this region and the integrity of the hydrophobic cluster at the base of this loop are necessary elements for the axial gate to efficiently translocate protein substrates. Analysis of ClpP variants from Bacillus subtilis suggested that the identified structural requirements of the axial channel for efficient translocation are conserved between Gram‐positive and Gram‐negative bacteria. These findings provide mechanistic insights into the activation of ClpP by ADEPs as well as the gating mechanism of the protease in the context of the ClpAP and ClpXP complexes.     

Cell therapy with autologous mesenchymal stromal cells in post-traumatic syringomyelia

Background aims

Recently, clinical studies show that cell therapy with mesenchymal stromal cells (MSCs) improves the sequelae chronically established in paraplegic patients, being necessary to know which of them can obtain better benefit.

Effects of salinity on the CO<Subscript>2</Subscript> permeation across lipid bilayer for microalgae biofixation: a molecular dynamics study

The continuous threat of increasing CO₂ concentration in the atmosphere has altered the carbon balance of our planet causing global climate change. Biological fixation of atmospheric CO₂ by unicellular microorganisms such as microalgae is a promising technology pursued extensively by researchers as a means for carbon capture. The study aimed to provide an atomic level of study that will demonstrate the effect of the salinity on the mechanism of CO₂ absorption across microalgae lipid bilayer. Molecular dynamics simulations were utilized to calculate the free energies of CO₂ molecule as it permeates inside the microalgae cell. In thermodynamics, the transport process of a molecule can be demonstrated through its free energy gradient. Thus, calculating the free energies of CO₂ molecule across microalgae lipid bilayer can elucidate the mechanisms of permeation processes. Four microalgae lipid bilayer structures were constructed that contains 128-DPPC (dipalmitoylphosphatidylcholine) lipid bilayer with 3640 water molecules with different NaCl concentrations: 0, 3, 13, and 19 NaCl molecules which correspond to a salinity level of 0, 50, 200, and 300 mM, respectively. The cavity insertion Widom method was used to calculate the free energy of CO₂ molecule along the lipid bilayer. The results demonstrated that the salinity does not affect the free energies significantly, thus, it does not hamper CO₂ transport across microalgae lipid membrane.     

Antiprotozoal and cysteine proteases inhibitory activity of dipeptidyl enoates

A family of dipeptidyl enoates has been prepared and tested against the parasitic cysteine proteases rhodesain, cruzain and falcipain-2 related to sleeping sickness, Chagas disease and malaria, respectively. They have also been tested against human cathepsins B and L1 for selectivity. Dipeptidyl enoates resulted to be irreversible inhibitors of these enzymes. Some of the members of the family are very potent inhibitors of parasitic cysteine proteases displaying k_2nd (M^?1s^?1) values of seven orders of magnitude. In vivo antiprotozoal testing was also performed. Inhibitors exhibited IC₅₀ values in the micromolar range against Plasmodium falciparum, Trypanosoma brucei, Trypanosoma cruzi and even more promising lower values against Leishmania donovanii.     

In situ behaviour of D(-)-lactate dehydrogenase from Escherichia coli

Some kinetic properties of the D(-)-lactate dehydrogenase (EC 1.1.1.28) of Escherichia coli have been investigated. There were marked differences between the kinetic properties of the enzyme studied in situ compared with the in vitro D(-)-lactate dehydrogenase. D(-)-Lactate dehydrogenase in situ showed high substrate inhibition with pyruvate over the pH range 6.0–7.0, whereas the enzyme in vitro did not. The pH optimum for pyruvate reduction by the in situ D(-)-lactate dehydrogenase ranged between pH 7.5 and 7.8, whereas the in vitro enzyme showed its pH optimum between pH 6.8 and 7.0. The pK values of the prototropic groups that controlled the enzymatic activity shift to the acidic region for the in vitro enzyme with respect to the in situ enzyme. In vitro D(-)-lactate dehydrogenase exhibits homotropic interactions with its substrate, pyruvate and its coenzyme, NADH, at pH values ranging between pH 6.0 and 8.5, but the in situ enzyme showed homotropic interactions neither with pyruvate nor with NADH at all pH values studied.     

Endothelial dysfunction in aged humans is related with oxidative stress and vascular inflammation

Vascular endothelial dysfunction occurs during the human aging process, and it is considered as a crucial event in the development of many vasculopathies. We investigated the underlying mechanisms of this process, particularly those related with oxidative stress and inflammation, in the vasculature of subjects aged 18–91 years without cardiovascular disease or risk factors. In isolated mesenteric microvessels from these subjects, an age‐dependent impairment of the endothelium‐dependent relaxations to bradykinin was observed. Similar results were observed by plethysmography in the forearm blood flow in response to acetylcholine. In microvessels from subjects aged less than 60 years, most of the bradykinin‐induced relaxation was due to nitric oxide release while the rest was sensitive to cyclooxygenase (COX) blockade. In microvessels from subjects older than 60 years, this COX‐derived vasodilatation was lost but a COX‐derived vasoconstriction occurred. Evidence for age‐related vascular oxidant and inflammatory environment was observed, which could be related to the development of endothelial dysfunction. Indeed, aged microvessels showed superoxide anions (O₂^?) and peroxynitrite (ONOO^?) formation, enhancement of NADPH oxidase and inducible NO synthase expression. Pharmacological interference of COX, thromboxane A₂/prostaglandin H₂ receptor, O₂^?, ONOO^?, inducible NO synthase, and NADPH oxidase improved the age‐related endothelial dysfunction. In situ vascular nuclear factor‐κB activation was enhanced with age, which correlated with endothelial dysfunction. We conclude that the age‐dependent endothelial dysfunction in human vessels is due to the combined effect of oxidative stress and vascular wall inflammation.     

Environmental genomics of Late Pleistocene black bears and giant short-faced bears

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