Proteome changes in platelets activated by arachidonic acid,collagen, and thrombin

Background  

Platelets are small anucleated blood particles that play a key role in the control of bleeding. Platelets need to be activated to perform their functions and participate in hemostasis. The process of activation is accompanied by vast protein reorganization and posttranslational modifications. The goal of this study was to identify changes in proteins in platelets activated by different agonists. Platelets were activated by three different agonists - arachidonic acid, collagen, and thrombin. 2D SDS-PAGE (pI 4-7) was used to separate platelet proteins. Proteomes of activated and resting platelets were compared with each other by Progenesis SameSpots statistical software; and proteins were identified by nanoLC-MS/MS.     

Exposure of beta-tubulin regions defined by antibodies on an <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>microtubule protofilament model and in the cells

Background  

The function of the cortical microtubules, composed of αβ-tubulin heterodimers, is linked to their organizational state which is subject to spatial and temporal modulation by environmental cues. The role of tubulin posttranslational modifications in these processes is largely unknown. Although antibodies against small tubulin regions represent useful tool for studying molecular configuration of microtubules, data on the exposure of tubulin epitopes on plant microtubules are still limited.     

Structure of a packaging-defective mutant of minute virus of mice indicates that the genome is packaged via a pore at a 5-fold axis

The parvovirus minute virus of mice (MVM) packages a single copy of its linear single-stranded DNA genome into preformed capsids, in a process that is probably driven by a virus-encoded helicase. Parvoviruses have a roughly cylindrically shaped pore that surrounds each of the 12 5-fold vertices. The pore, which penetrates the virion shell, is created by the juxtaposition of 10 antiparallel β-strands, two from each of the 5-fold-related capsid proteins. There is a bottleneck in the channel formed by the symmetry-related side chains of the leucines at position 172. We report here the X-ray crystal structure of the particles produced by a leucine-to-tryptophan mutation at position 172 and the analysis of its biochemical properties. The mutant capsid had its 5-fold channel blocked, and the particles were unable to package DNA, strongly suggesting that the 5-fold pore is the packaging portal for genome entry.     

Mutational and structural analyses of the hinge region of membrane type 1-matrix metalloproteinase and enzyme processing

Membrane type 1 (MT1)-matrix metalloproteinase (MMP) is a major mediator of collagen degradation in the pericellular space in both physiological and pathological conditions. Previous evidence has shown that on the cell surface, active MT1-MMP undergoes autocatalytic processing to a major membrane-tethered 44-kDa product lacking the catalytic domain and displaying Gly285 at its N terminus, which is at the beginning of the hinge domain. However, the importance of this site and the hinge region in MT1-MMP processing is unknown. In the current study, we generated mutations and deletions in the hinge of MT1-MMP and followed their effect on processing. These studies established Gly284-Gly285 as the main cleavage site involved in the formation of the 44-kDa species. However, alterations at this site did not prevent processing. Instead, they forced downstream cleavages within the stretch of residues flanked by Gln296 and Ser304 in the hinge region, as determined by the processing profile of various hinge deletion mutants. Also, replacement of the hinge of MT1-MMP with the longer MT3-MMP hinge did not prevent processing of MT1-MMP. Molecular dynamic studies using a computational model of MT1-MMP revealed that the hinge region is a highly motile element that undergoes significant motion in the highly exposed loop formed by Pro295-Arg302 consistent with being a prime target for proteolysis, in agreement with the mutational data. These studies suggest that the hinge of MT1-MMP evolved to facilitate processing, a promiscuous but compulsory event in the destiny of MT1-MMP, which may play a key role in the control of pericellular proteolysis.     

Long-term follow-up of childhood-onset hypopituitarism in patients with the PROP-1 gene mutation

OBJECTIVE: The PROP-1 gene mutation is a rare disorder leading to combined pituitary hormone deficiencies over time. The aim was to analyze the clinical picture of 40 years of an almost untreated PROP-1 gene mutation. METHODS: We describe the clinical and hormonal data of 2 brothers from childhood to adulthood as well as imaging procedures (MRI of the pituitary gland, bone mineral density by QCT and DPX). The PROP-1 gene mutation (301-302delAG) was confirmed by DNA sequencing. RESULTS: Although long-standing untreated hypopituitarism was present, there was normal physical and professional activity. Bone mineral density was low only in 1 patient. Adrenocortical deficiency occurred late at 45 and 39 years. CONCLUSIONS: The biological evolution of the PROP-1 gene mutation illustrates the importance of continuous care for these patients. Hormonal deficiencies do not necessarily lead to the same phenotype as is obvious in differences of bone age and bone mineral density.     

Variation in the uptake of Arsenic, Cadmium, Lead, and Zinc by different species of willows Salix spp. grown in contaminated soils

The experiment assessed the variability of in seven clones of willow plants of high biomass production (Salix smithiana S-218, Salix smithiana S-150, Salix viminalis S-519, Salix alba S-464, Salix ’Pyramidalis’ S-141, Salix dasyclados S-406, Salix rubens S-391). They were planted in a pots for three vegetation periods in three soils differing in the total content of risk elements. Comparing the calculated relative decrease of total metal contents in soils, the phytoextraction potential of willows was obtained for cadmium (Cd) and zinc (Zn), moderately contaminated Cambisol and uncontaminated Chernozem, where aboveground biomass removed about 30% Cd and 5% Zn of the total element content, respectively. The clones showed variability in removing Cd and Zn, depending on soil type and contamination level: S. smithiana (S-150) and S. rubens (S-391) demonstrated the highest phytoextraction effect for Cd and Zn. For lead (Pb) and arsenic (As), the ability to accumulate the aboveground biomass of willows was found to be negligible in both soils. The results confirmed that willow plants show promising results for several elements, mainly for mobile ones like cadmium and zinc in moderate levels of contamination. The differences in accumulation among the clones seemed to be affected more by the properties of clones, not by the soil element concentrations or soil properties. However, confirmation and verification of the results in field conditions as well as more detailed investigation of the mechanisms of cadmium uptake in rhizosphere of willow plants will be determined by further research.     

Artificial selection on brain size leads to matching changes in overall number of neurons

Neurons are the basic computational units of the brain, but brain size is the predominant surrogate measure of brain functional capacity in comparative and cognitive neuroscience. This approach is based on the assumption that larger brains harbor higher numbers of neurons and their connections, and therefore have a higher information‐processing capacity. However, recent studies have shown that brain mass may be less strongly correlated with neuron counts than previously thought. Till now, no experimental test has been conducted to examine the relationship between evolutionary changes in brain size and the number of brain neurons. Here, we provide such a test by comparing neuron number in artificial selection lines of female guppies (Poecilia reticulata) with >15% difference in relative brain mass and numerous previously demonstrated cognitive differences. Using the isotropic fractionator, we demonstrate that large‐brained females have a higher overall number of neurons than small‐brained females, but similar neuronal densities. Importantly, this difference holds also for the telencephalon, a key region for cognition. Our study provides the first direct experimental evidence that selection for brain mass leads to matching changes in number of neurons and shows that brain size evolution is intimately linked to the evolution of neuron number and cognition.     

Two types of PS II centres as manifested by light saturation of delayed fluorescence from DCMU-treated chloroplasts

Intensity of 2 s delayed fluorescence (DF) as a function of steady-state actinic light intensity was investigated in pea chloroplasts in the presence of 10 M DCMU. The light saturation curve of DF was approximated by a sum of two hyperbolic components which differ by an order of magnitude in the half-saturating incident light intensity. The relative contribution of the amplitudes of the components was practically independent of cation (Na⁺ and Mg²⁺) concentration and a short-term heating of the chloroplasts at 45°C. The component saturating at low incident light intensity was selectively suppressed by 100 M DCMU or by 1 mol g^-1 Chl oleic acid. DF intensity following excitation by a single saturating 15 s flash was equal to the intensity of the component saturating at a low incident light intensity. Upon flash excitation, the maximum steady-state DF level was found to be attained only after a series of saturating flashes. It is concluded that the two components of the DF light saturation curves are related to PS II centres heterogeneity in quantum yield of stabilization of the reduced primary quinone acceptor.Abbreviations DF Delayed fluorescence - L₁- and L₂-components DF components saturating at low and high incident light intensity, respectively - I incident light intensity - L DF intensity - P₆₈₀ reaction centre chlorophyll of PS II - Q_A and Q_B primary and secondary quinone acceptors of PS II, respectively