A new minimal synthetic medium for germ-tube production in Candida albicans

A new minimal synthetic medium, with low amount of glucose, without aminoacids, vitamins and neutral pH, which induces germ-tubes production in Candida albicans, is reported in this work. The results indicate a perfect agreement between the germ-tube test performed with the standard method in human or animal serum and this test performed in minimal synthetic medium. In this medium the germ-tube test for the presumptive identification of Candida albicans can be performed with the same formality, time and reproducibility as those in human or animal serum. This constitutes an interesting finding because it is easy to prepare, to store and is highly reproducible.     

Interplay between mobility,multi-seeding and lockdowns shapes COVID-19 local impact

Assessing the impact of mobility on epidemic spreading is of crucial importance for understanding the effect of policies like mass quarantines and selective re-openings. While many factors affect disease incidence at a local level, making it more or less homogeneous with respect to other areas, the importance of multi-seeding has often been overlooked. Multi-seeding occurs when several independent (non-clustered) infected individuals arrive at a susceptible population. This can lead to independent outbreaks that spark from distinct areas of the local contact (social) network. Such mechanism has the potential to boost incidence, making control efforts and contact tracing less effective. Here, through a modeling approach we show that the effect produced by the number of initial infections is non-linear on the incidence peak and peak time. When case importations are carried by mobility from an already infected area, this effect is further enhanced by the local demography and underlying mixing patterns: the impact of every seed is larger in smaller populations. Finally, both in the model simulations and the analysis, we show that a multi-seeding effect combined with mobility restrictions can explain the observed spatial heterogeneities in the first wave of COVID-19 incidence and mortality in five European countries. Our results allow us for identifying what we have called epidemic epicenter: an area that shapes incidence and mortality peaks in the entire country. The present work further clarifies the nonlinear effects that mobility can have on the evolution of an epidemic and highlight their relevance for epidemic control.     

Barth syndrome: Cellular compensation of mitochondrial dysfunction and apoptosis inhibition due to changes in cardiolipin remodeling linked to tafazzin (TAZ) gene mutation

Cardiolipin is a mitochondrion-specific phospholipid that stabilizes the assembly of respiratory chain complexes, favoring full-yield operation. It also mediates key steps in apoptosis. In Barth syndrome, an X chromosome-linked cardiomyopathy caused by tafazzin mutations, cardiolipins display acyl chain modifications and are present at abnormally low concentrations, whereas monolysocardiolipin accumulates. Using immortalized lymphoblasts from Barth syndrome patients, we showed that the production of abnormal cardiolipin led to mitochondrial alterations. Indeed, the lack of normal cardiolipin led to changes in electron transport chain stability, resulting in cellular defects. We found a destabilization of the supercomplex (respirasome) I + III₂ + IV_n but also decreased amounts of individual complexes I and IV and supercomplexes I + III and III + IV. No changes were observed in the amounts of individual complex III and complex II. We also found decreased levels of complex V. This complex is not part of the supercomplex suggesting that cardiolipin is required not only for the association/stabilization of the complexes into supercomplexes but also for the modulation of the amount of individual respiratory chain complexes. However, these alterations were compensated by an increase in mitochondrial mass, as demonstrated by electron microscopy and measurements of citrate synthase activity. We suggest that this compensatory increase in mitochondrial content prevents a decrease in mitochondrial respiration and ATP synthesis in the cells. We also show, by extensive flow cytometry analysis, that the type II apoptosis pathway was blocked at the mitochondrial level and that the mitochondria of patients with Barth syndrome cannot bind active caspase-8. Signal transduction is thus blocked before any mitochondrial event can occur. Remarkably, basal levels of superoxide anion production were slightly higher in patients' cells than in control cells as previously evidenced via an increased protein carbonylation in the taz1Δ mutant in the yeast. This may be deleterious to cells in the long term. The consequences of mitochondrial dysfunction and alterations to apoptosis signal transduction are considered in light of the potential for the development of future treatments.     

Genetic diversity of the sweet chestnut (<Emphasis Type="Italic">Castanea sativa</Emphasis> Mill.) in Central Europe and the western part of the Balkan Peninsula and evidence of marron genotype introgression into wild populations

The sweet chestnut (Castanea sativa Mill.) is a widely spread and important multipurpose tree species in the Mediterranean area, which has played an important role in human history. Natural events, such as glaciations, and human influence played significant roles in the distribution and genetic makeup of the sweet chestnut. In order to better understand how natural and human-mediated past events affected the current genetic diversity and structure of the sweet chestnut, we analysed populations from Central Europe and the western part of the Balkan Peninsula, utilizing ten polymorphic nuclear microsatellite markers. The study revealed the existence of three genetically and, to a large extent, geographically distinct and well-defined groups of sweet chestnut populations. Two not entirely separated groups of populations were detected in the northern part of the studied area and one in the southern. Our results indicate that the genetic structure of sweet chestnut populations in Central Europe and the western part of the Balkan Peninsula is the result of both natural colonization events and significant and lengthy human impact. Furthermore, it has been proven that the gene flow between cultivated/grafted trees’ and wild chestnut stands can influence their genetic structure. However, our results reveal that cultivated-to-wild introgression in the sweet chestnut is dependent on the close proximity of chestnut orchards and naturally occurring populations.     

Role of protein kinases CK1α and CK2 in multiple myeloma: regulation of pivotal survival and stress-managing pathways

Multiple myeloma (MM) is a malignant tumor of transformed plasma cells. MM pathogenesis is a multistep process. This cancer can occur de novo (rarely) or it can develop from monoclonal gammopathy of undetermined significance (most of the cases). MM can be asymptomatic (smoldering myeloma) or clinically active. Malignant plasma cells exploit intrinsic and extrinsic bone marrow microenvironment-derived growth signals. Upregulation of stress-coping pathways is also instrumental to maintain MM cell growth. The phylogenetically related Ser/Thr kinases CSNK1A1 (CK1α) and CSNK2 (CK2) have recently gained a growing importance in hematologic malignancies arising both from precursors and from mature blood cells. In multiple myeloma, CK1α or CK2 sustain oncogenic cascades, such as the PI3K/AKT, JAK/STAT, and NF-κB, as well as propel stress-related signaling that help in coping with different noxae. Data also suggest that these kinases modulate the delivery of growth factors and cytokines from the bone marrow stroma. The “non-oncogene addiction” phenotype generated by the increased activity of CK1α and CK2 in multiple myeloma contributes to malignant plasma cell proliferation and survival and represents an Achilles’ heel for the activity of small ATP competitive CK1α or CK2 inhibitors.     

Effect of positive charge in VIP 16gamma-glutamyl diamino derivatives on hVPAC1 and hVPAC2 receptor function.

Increase of VPAC receptor s binding to the (16)gamma-glutamyl diaminopropane vasoactive intestinal peptide (VIP-DAP) agonist, a vasoactive intestinal polypeptide (VIP) structural analogue containing a positive charge at position 16, has confirmed the importance of a positive charge at this site. By investigating the effect of distance from the peptide backbone Calpha of a positive charge in position 16, data are reported here concerning: (i) a novel chemical method used for the synthesis of a new family of (16)gamma-glutamyl diamine VIP derivatives differing among them for single carbon atoms and including diaminoethane (VIP-DAE2), diaminopropane (VIP-DAP3), diaminobutane (VIP-DAB4), diaminopentane (VIP-DAP5), and diaminohexane (VIP-DAH6); (ii) functional characterization of these compounds on human VPAC1 and VPAC2 receptors. In more detail, the EC50 and IC50 values, when measured as a function of the alkylic chain length, show in more detail, that the use of VIP-DAB4 derivative changes the IC50 but not the EC50, thus indicating on hVPAC2 receptor an unexpected relationship between binding and activity that differs from that obtained on hVPAC1.     

Metal swap between Zn7-metallothionein-3 and amyloid-beta-Cu protects against amyloid-beta toxicity

Aberrant interactions of copper and zinc ions with the amyloid-beta peptide (Abeta) potentiate Alzheimer's disease (AD) by participating in the aggregation process of Abeta and in the generation of reactive oxygen species (ROS). The ROS production and the neurotoxicity of Abeta are associated with copper binding. Metallothionein-3 (Zn(7)MT-3), an intra- and extracellularly occurring metalloprotein, is highly expressed in the brain and downregulated in AD. This protein protects, by an unknown mechanism, cultured neurons from the toxicity of Abeta. Here, we show that a metal swap between Zn(7)MT-3 and soluble and aggregated Abeta(1-40)-Cu(II) abolishes the ROS production and the related cellular toxicity. In this process, copper is reduced by the protein thiolates forming Cu(I)(4)Zn(4)MT-3, in which an air-stable Cu(I)(4)-thiolate cluster and two disulfide bonds are present. The discovered protective effect of Zn(7)MT-3 from the copper-mediated Abeta(1-40) toxicity may lead to new therapeutic strategies for treating AD.