Differenze Ultrastrutturali Di Alcune Specie Di Trebouxia Poste in Condizioni Di Illuminazione Differenti

Abstract

Ultrastructural changes in some species of « Trebouxia » under different light conditions. — Some species of the phycobiont alga Trebouxia (Tr. decolorans and Tr. albulescens), both isolated and grown on synthetic medium and still in the lichen, were examined in order to study the effect of light on the plastid ultrastructures. The species isolated from Buellia punctata and Xanthoria parietina were very sensitive to light condition and lost their chlorophyll content quickly. Striking ultrastructural changes were found in the algae grown under small light intensities and those which become achloric owing to strong light. In the latter, modifications of the Iamellar System were observed. The disappearance of Chlorophyll pigments was followed by a reduced electron density of the whole Iamellar system, as if were lacking the Iipidic compounds which are usually present and absorb fixators and dyers, thus allowing a good view. On the contrary, normal light conditions did not affect cultures of Trebouxia humicola, a free living alga. In the chloroplasts of the phycobiont species, unlike in the free living alga, grana were very close and sometimes formed very thick masses towards the edge of the chloroplast. It could not be ascertained whether such changes corresponded to a different composition of the lipoproteic compounds of the lamellar system.

Xanthoria parietina could grow in very lighted environments with no damage of the algae present in its thallus. The lichen thalluses, under different light conditions, showed very different colourings: the overlighted ones were rusty-red and the shadowed ones deep green. The chlorophyll content of the lichen thalluses with various shades (table 1) were very similar. The ultrastructural changes induced by strong light intensities in the phycobiont algae, kept in the lichen, were very small in respect of those observed in the same algae isolated and grown on synthetic medium and concerned the Iamellar system and the pyrenoid, above all. The rusty-red lichen showed a great number of stromatic lamellae, often with a parallel trend, so as to simulate a Iamellar system not organized in grana and often presented groups of lamellae concentrically arranged. In the pyrenoid of the algae from rusty-red thalluses, compared with the green ones, a much greater number of electron dense masses was observed, which are very thick and occupy the whole stromatic portion of the pyrenoid. But the Chlorophyll content did not decrease. Unlike the results of PEVELING, we noted that the electron dense masses (cited by the Author as « osmiophilic plastoglobules) were visible even after fixation with permanganate; the different numbers of these globules might depend on environmental factors. The phycobiont alga, when in the lichen thallus, could perhaps support strong light intensities, because pigments or compounds formed with the mycobiont or by it alone prevented the photooxidation of chlorophyll. Hypothetically a relationship might exist between the sensitivity of the phycobiont algae to light intensities and the content in antraquinonic pigments in the lichen thallus. But also using filters with absorption maxima similar to those of these pigments, the « in vitro » cultures of the phycobiont algae became achloric in the same time as the control ones.

Some Authors had found in Trebouxia humicola a different relationship between Chlorophyll pigments and carotinoids from that observed in the phycobiont species and had ascribed to it the greater resistence to strong light of the free living alga. Pigments or other substances present in the mycobiont can have a protective action on the Chlorophyll content and on the ultrastructures. In the phycobiont algae the resistence to strong light might be explained by an exchange of compounds between mycobiont and phycobiont, ending with the structural changes of the pyrenoid.     

Specifically Human: Going Beyond Perceptual Syntax

The aim of this paper is to help refine the definition of humans as “linguistic animals” in light of a comparative approach on nonhuman animals’ cognitive systems. As Uexküll & Kriszat (1934/1992) have theorized, the epistemic access to each species-specific environment (Umwelt) is driven by different biocognitive processes. Within this conceptual framework, I identify the salient cognitive process that distinguishes each species typical perception of the world as the faculty of language meant in the following operational definition: the ability to connect different elements according to structural rules. In order to draw some conclusions about humans’ specific faculty of language, I review different empirical studies on nonhuman animals’ ability to recognize formal patterns of tokens. I suggest that what differentiates human language from other animals’ cognitive systems is the ability to categorize the units of a pattern, going beyond its perceptual aspects. In fact, humans are the only species known to be able to combine semantic units within a network of combinatorial logical relationships (Deacon 1997) that can be linked to the state of affairs in the external world (Wittgenstein 1922). I assume that this ability is the core cognitive process underlying a) the capacity to speak (or to reason) in verbal propositions and b) the general human faculty of language expressed, for instance, in the ability to draw visual conceptual maps or to compute mathematical expressions. In light of these considerations, I conclude providing some research questions that could lead to a more detailed comparative exploration of the faculty of language.     

Secretome compartment is a valuable source of biomarkers for cancer-relevant pathways

In principle, targeted therapies have optimal activity against a specific subset of tumors that depend upon the targeted molecule or pathway for growth, survival, or metastasis. Consequently, it is important in drug development and clinical practice to have predictive biomarkers that can reliably identify patients who will benefit from a given therapy. We analyzed tumor cell-line secretomes (conditioned cell media) to look for predictive biomarkers; secretomes represent a potential source for potential biomarkers that are expressed in intracellular signaling and therefore may reflect changes induced by targeted therapy. Using Gene Ontology, we classified by function the secretome proteins of 12 tumor cell lines of different histotypes. Representations and hierarchical relationships among the functional groups differed among the cell lines. Using bioinformatics tools, we identified proteins involved in intracellular signaling pathways. For example, we found that secretome proteins related to TGF-beta signaling in thyroid cancer cells, such as vasorin, CD109, and βIG-H3 (TGFBI), were sensitive to RPI-1 and dasatinib treatments, which have been previously demonstrated to be effective in blocking cell proliferation. The secretome may be a valuable source of potential biomarkers for detecting cancer and measuring the effectiveness of cancer therapies.     

Protein Kinase C ε Expression in Platelets from Patients with Acute Myocardial Infarction

Objective

Platelets play crucial roles in the pathophysiology of thrombosis and myocardial infarction. Protein kinase C ε (PKCε) is virtually absent in human platelets and its expression is precisely regulated during human megakaryocytic differentiation. On the basis of what is known on the role of platelet PKCε in other species, we hypothesized that platelets from myocardial infarction patients might ectopically express PKCε with a pathophysiological role in the disease.

Methods and Results

We therefore studied platelet PKCε expression from 24 patients with myocardial infarction, 24 patients with stable coronary artery disease and 24 healthy subjects. Indeed, platelets from myocardial infarction patients expressed PKCε with a significant frequency as compared to both stable coronary artery disease and healthy subjects. PKCε returned negative during patient follow-up. The forced expression of PKCε in normal donor platelets significantly increased their response to adenosine diphosphate-induced activation and adhesion to subendothelial collagen.

Conclusions

Our data suggest that platelet generations produced before the acute event retain PKCε-mRNA that is not down-regulated during terminal megakaryocyte differentiation. Results are discussed in the perspective of peri-infarctual megakaryocytopoiesis as a critical component of myocardial infarction pathophysiology.     

Bovine lactoferrin in preventing preterm delivery associated with sterile inflammation

Preterm delivery (PTD) occurs before the 37th week of gestation. Iron deficiency anemia and inflammatory processes either related to infection or sterile inflammatory response represent risk factors for PTD. Bovine lactoferrin (bLf), an emerging important regulator of iron and inflammatory homeostasis, can represent a new therapeutic approach for PTD treatment. Here an open-label cohort and subcohort study is reported. The cohort was designed to assess the effect of bLf oral administration on iron and inflammatory homeostasis in anemic pregnant women. The subcohort including women of the cohort with PTD threat was additionally treated with bLf intravaginal administration. A significant improvement of hematological parameters was observed in the women's cohort together with a consistent decrease of serum interleukin-6 (IL-6) levels. Combined administration of oral and intravaginal bLf to the women's subcohort with PTD threat decreased IL-6 in both serum and cervicovaginal fluids, cervicovaginal prostaglandin F(2α), and suppressed uterine contractility. BLf administration blocked further shortening of cervical length and the increase of fetal fibronectin thus prolonging the length of pregnancy. The deliveries occurred between the 37th and 38th week of gestation. These results provide strong evidence for a role of bLf in PTD treatment, thus extending the therapeutic potential of this multifunctional natural protein.     

Ca2+ binding to bovine lactoferrin enhances protein stability and influences the release of bacterial lipopolysaccharide.

Bovine lactoferrin (bLf) is known to damage the outer membrane of Gram-negative bacteria by binding to bacterial lipopolysaccharide (LPS). We report that LPS is released from bacterial outer membranes also when apo- or metal-saturated Lf is separated from bacterial cells by a dialysis membrane. This process occurs in phosphate-buffered saline with no added Ca2+ and Mg2+ and is hindered by addition of these cations. The effect of bLf is similar to that induced by EDTA and has been ascribed to chelation of Ca2+. In fact, it may be envisaged that Ca2+-binding sites on LPS have different affinities and that bLf can remove those ions that are more weakly bound. Ca2+ binding does not alter Lf iron-binding properties significantly or its UV and CD spectral features but brings about changes in the FT-IR bands due to carboxylate residues. Ca2+ binding is characterized by an apparent dissociation constant of 6 microM and a stoichiometry of 1.55 Ca2+ per Lf molecule; it enhances bLf stability towards chemical and thermal denaturation. The increase in stability takes place in both the apo- and iron-saturated forms but not in the desialilated protein, indicating that the carboxylate groups of the sialic acid residues present on two of the glycan chains are involved in Ca2+ binding.     

Transfer of chirality by dithiophosphate ligands and chiral discrimination in the stereoselective formation of square-planar Ni(II) complexes

In the formation reaction of Ni(2+) with the chiral racemic ligand, (R)(R)bdtp(-)/(S)(S)bdtp(-), bdtp(-) = [SSPOCH)CH(3))CH(CH(3))O](-), cyclo- O,O'-[1,2-dimethylethylene] dithiophosphato ion, the meso-complex Ni[(R)(R)(lambda)bdtp][(S)(S)(delta)-bdtp] is stereoselectively produced. The meso-complex was compared with the enantiopure crystals of (+)(589)Ni[(R)(R)(lambda)bdtp](2) or (-)(589)Ni[(S)(S)(delta)bdtp](2), as well as racemic crystals, rac-(+/-)Ni[bdtp](2), which were prepared from the solution containing the two enantiomers in a 1:1 ratio. Dissociation constants in solutions indicate different stability of the meso and enantiopure complexes depending on the solvent, whereas a more efficient crystal packing, weak H-bonding, and nonbonding interactions contribute to stabilization of the meso-species over the racemic one. Molecular structures show that the outer five-membered ligand ring adopts the half-chair conformation C(2) with either the lambda or the delta chirality and the methyl groups are in equatorial (e) positions. Enantiopure ligands of (+)(589)Ni[(R)(R)(lambda)bdtp](2) and (-)(589)Ni[(S)(S)(delta)bdtp](2) induce chirality into the symmetric SSNiSS chromophore with slightly helical distortion. Thus, their CD spectra exhibit weak negative or positive Cotton effects at 662 nm. CD spectra in L(+)- and D(-)diethyltartrate of the meso-complex and racemic crystal, rac-(+/-)Ni[bdtp](2), exhibit different weak Cotton effects of opposite sign. Complexes dissociate in methanol; rac-(+/-)Ni[bdtp](2) in methanol undergoes a crystallization-induced second-order asymmetric transformation which finally yields crystals of the meso-Ni[(R)(R)(lambda)bdtp][(S)(S)(delta)bdtp] complex.     

SHH-N upregulates Sfrp2 to mediate its competitive interaction with WNT1 and WNT4 in the somitic mesoderm

Dorsoventral polarity of the somitic mesoderm is established by competitive signals originating from adjacent tissues. The ventrally located notochord provides the ventralizing signals to specify the sclerotome, while the dorsally located surface ectoderm and dorsal neural tube provide the dorsalizing signals to specify the dermomyotome. Noggin and SHH-N have been implicated as the ventralizing signals produced by the notochord. Members of the WNT family of proteins, on the other hand, have been implicated as the dorsalizing signals derived from the ectoderm and dorsal neural tube. When presomitic explants are confronted with cells secreting SHH-N and WNT1 simultaneously, competition to specify the sclerotome and dermomyotome domains within the naive mesoderm can be observed. Here, using these explant cultures, we provide evidence that SHH-N competes with WNT1, not only by upregulating its own receptor Ptc1, but also by upregulating Sfrp2 (Secreted frizzled-related protein 2), which encodes a potential WNT antagonist. Among the four known Sfrps, Sfrp2 is the only member expressed in the sclerotome and upregulated by SHH-N recombinant protein. We further show that SFRP2-expressing cells can reduce the dermomyotome-inducing activity of WNT1 and WNT4, but not that of WNT3a. Together, our results support the model that SHH-N at least in part employs SFRP2 to reduce WNT1/4 activity in the somitic mesoderm.     

P62 deficiency shifts mesenchymal/stromal stem cell commitment toward adipogenesis and disrupts bone marrow homeostasis in aged mice

With advancing age have been observed bone and bone marrow phenotypic alterations due to the impaired bone tissue homeostatic features, involving bone remodeling, and bone marrow niche ontogeny. The complex “inflamm-aging” pathological scenario that culminates with osteopenia and mesenchymal/stromal and hematopoietic stem cell commitment breakdown, is controlled by cellular and molecular intramural components comprising adapter proteins such as the sequestosome 1 (p62/SQSTM1). p62, a “multiway function” protein, has been reported as an effective anti-inflammatory, bone-building factor. In this view, we considered for the first time the involvement of p62 in aging bone and bone marrow of 1 year and 2 years p62^−/− mice. Interestingly, p62 deficiency provoked accelerated osteopenia and impaired niche operational activities within the bone marrow. The above findings unearthed the importance of p62 in mesenchymal stem cell maintenance/differentiation schedule in old animals and provide, at least in part, a mechanistic scenario of p62 action.