Stereocontrolled synthesis of new iminosugar lipophilic derivatives and evaluation of biological activities

Iminosugars' similarity to carbohydrates determines the exceptional potential for this class of polyhydroxylated alkaloids to serve as potential drug candidates for a wide variety of diseases such as diabetes, lysosomal storage diseases, cancer, bacterial and viral infections. The presence of lipophilic substituents has a significant impact on their biological activities. This work reports the synthesis of three new pyrrolidine lipophilic derivatives O-alkylated in C-6 position. The biological activities of our iminosugars' collection were tested in two cancer cell lines and, due to the pharmaceutical potential, in the model yeast system Saccharomyces cerevisiae to assess their toxicity.

Upscaling of Electrospinning Technology and the Application of Functionalized PVDF-HFP@TiO2 Electrospun Nanofibers for the Rapid Photocatalytic Deactivation of Bacteria on Advanced Face Masks

In recent years, Electrospinning (ES) has been revealed to be a straightforward and innovative approach to manufacture functionalized nanofiber-based membranes with high filtering performance against fine Particulate Matter (PM) and proper bioactive properties. These qualities are useful for tackling current issues from bacterial contamination on Personal Protective Equipment (PPE) surfaces to the reusability of both disposable single-use face masks and respirator filters. Despite the fact that the conventional ES process can be upscaled to promote a high-rate nanofiber production, the number of research works on the design of hybrid materials embedded in electrospun membranes for face mask application is still low and has mainly been carried out at the laboratory scale. In this work, a multi-needle ES was employed in a continuous processing for the manufacturing of both pristine Poly (Vinylidene Fluoride-co-Hexafluoropropylene) (PVDF-HFP) nanofibers and functionalized membrane ones embedded with TiO2 Nanoparticles (NPs) (PVDF-HFP@TiO2). The nanofibers were collected on Polyethylene Terephthalate (PET) nonwoven spunbond fabric and characterized by using Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX), Raman spectroscopy, and Atomic Force Microscopy (AFM) analysis. The photocatalytic study performed on the electrospun membranes proved that the PVDF-HFP@TiO2 nanofibers provide a significant antibacterial activity for both Staphylococcus aureus (~94%) and Pseudomonas aeruginosa (~85%), after only 5 min of exposure to a UV-A light source. In addition, the PVDF-HFP@TiO2 nanofibers exhibit high filtration efficiency against submicron particles (~99%) and a low pressure drop (~3 mbar), in accordance with the standard required for Filtering Face Piece masks (FFPs). Therefore, these results aim to provide a real perspective on producing electrospun polymer-based nanotextiles with self-sterilizing properties for the implementation of advanced face masks on a large scale.

The representation of child-parent relation: validation of the Italian version of the child-parent relationship scale (CPRS-I)

This study proposes a psychometric validation of the Italian version of the Child-Parent Relationship Scale (CPRS) developed by Pianta in 1992. Based on attachment theory, the scale assesses parents' relationship perceptions with their own child and comprises three scales: Closeness, Conflict, and Dependency. A sample of 501 parents (188 fathers and 313 mothers) completed 30 items of the Italian version of the Child-Parent Relationship Scale (CPRS-I) online, but only 437 answered 85% of the entire protocol; hence, the analyses only focused on 437 participants. The first analysis of the original theoretical model revealed poor fit, item loadings, and internal consistency. Therefore, a follow-up analysis was conducted. Exploratory and confirmatory analyses with a split sample (EFA = 218; CFA = 219) confirmed the original three-factor structure of the Italian sample, although some items were eliminated. The validity and reliability of the Italian version of the CPRS-I were also verified by correlating the above three factors with measures of adult attachment styles and children's internalizing and externalizing behaviors. The CPRS-I showed significant correlations with all tested constructs, in line with those found by Driscoll and Pianta for the short form of the scale. Our results confirm that the CPRS-I has the same structure as the original scale; therefore, it can be a useful tool for assessing parents' perceptions of their relationship with their children. The implications for educational and clinical settings are also discussed.

H3 Lysine 4 Methylation Is Required for Full Activation of Genes Involved in α-Ketoglutarate Availability in the Nucleus of Yeast Cells after Diauxic Shift

We show that in S. cerevisiae the metabolic diauxic shift is associated with a H3 lysine 4 tri-methylation (H3K4me3) increase which involves a significant fraction of transcriptionally induced genes which are required for the metabolic changes, suggesting a role for histone methylation in their transcriptional regulation. We show that histone H3K4me3 around the start site correlates with transcriptional induction in some of these genes. Among the methylation-induced genes are IDP2 and ODC1, which regulate the nuclear availability of α-ketoglutarate, which, as a cofactor for Jhd2 demethylase, regulates H3K4 tri-methylation. We propose that this feedback circuit could be used to regulate the nuclear α-ketoglutarate pool concentration. We also show that yeast cells adapt to the absence of Jhd2 by decreasing Set1 methylation activity.

PNC2 (SLC25A36) Deficiency Associated With the Hyperinsulinism/Hyperammonemia Syndrome

CONTEXT

The hyperinsulinism/hyperammonemia (HI/HA) syndrome, the second-most common form of congenital hyperinsulinism, has been associated with dominant mutations in GLUD1, coding for the mitochondrial enzyme glutamate dehydrogenase, that increase enzyme activity by reducing its sensitivity to allosteric inhibition by GTP.

OBJECTIVE

To identify the underlying genetic etiology in 2 siblings who presented with the biochemical features of HI/HA syndrome but did not carry pathogenic variants in GLUD1, and to determine the functional impact of the newly identified mutation.

METHODS

The patients were investigated by whole exome sequencing. Yeast complementation studies and biochemical assays on the recombinant mutated protein were performed. The consequences of stable slc25a36 silencing in HeLa cells were also investigated.

RESULTS

A homozygous splice site variant was identified in solute carrier family 25, member 36 (SLC25A36), encoding the pyrimidine nucleotide carrier 2 (PNC2), a mitochondrial nucleotide carrier that transports pyrimidine as well as guanine nucleotides across the inner mitochondrial membrane. The mutation leads to a 26-aa in-frame deletion in the first repeat domain of the protein, which abolishes transport activity. Furthermore, knockdown of slc25a36 expression in HeLa cells caused a marked reduction in the mitochondrial GTP content, which likely leads to a hyperactivation of glutamate dehydrogenase in our patients.

CONCLUSION

We report for the first time a mutation in PNC2/SLC25A36 leading to HI/HA and provide functional evidence of the molecular mechanism responsible for this phenotype. Our findings underscore the importance of mitochondrial nucleotide metabolism and expand the role of mitochondrial transporters in insulin secretion.

Learning to Wait and Be Altruistic: Testing A Conversational Training in Economic Education for Primary School Children

Individual economic competence is important but increasingly challenging to manage due to the growing complexity of the nature of economic decisions people must make and the substantial impacts of some of these decisions on their lives. Decision-making ability develops from childhood and is closely related to specific economic components and prosocial behaviour such as fairness, altruism, and delay of gratification. However, while there are financial-education programs for children and young people focusing on financial products, few studies have examined training for the psychological abilities underlying economic decision-making. To promote those psychological skills that contribute to a more socially effective decision-making, we designed and tested a conversational-based training program for primary school children using reflective thinking. A total of 110 (male = 47, female = 63) children aged 8 to 10 years (Mean age = 9.71 years) from two schools in Northern Italy participated in the study with 55 children in a training group and 55 in a control group. All participated in pre-tests measuring their socio-economic background and economics-related skills and abilities. The training group were told stories relaying values of fairness, altruism, and delayed gratification. Both groups participated in task-based post-tests relating to fairness, altruism, and delayed gratification. Results revealed that children in the training group showed significant improvement at the post-test in altruistic and investment behaviour, showing the training efficacy, suggesting that similar programs could be implemented in primary schools as foundational teaching of economics and fiscal responsibility.

The C-terminal region of yeast ubiquitin-protein ligase Not4 mediates its cellular localization and stress response

Transient modification of the environment involves the expression of specific genes and degradation of mRNAs and proteins. How these events are linked is poorly understood. CCR4-NOT is an evolutionary conserved complex involved in transcription initiation and mRNA degradation. In this paper, we report that the yeast Not4 localizes in cytoplasmic foci after cellular stress. We focused our attention on the functional characterization of the C-terminus of the Not4 protein. Molecular dissection of this region indicates that the removal of the last 120 amino acids, does not affect protein localization and function, in that the protein is still able to suppress the thermosensitivity observed in the not4Δ mutant. In addition, such shortened form of Not4, as well its absence, increases the transcription of stress-responsive genes conferring to the cell high resistance to the oxidative stress. On the contrary, the last C-terminal 211 amino acids are required for proper Not4 localization at cytoplasmic foci after stress. This truncated version of Not4 fails to increase the transcription of the stress genes, is more stable and seems to be toxic to cells undergoing oxidative stress.

Astrobiology of life on Earth

Astrobiology is mistakenly regarded by some as a field confined to studies of life beyond Earth. Here, we consider life on Earth through an astrobiological lens. Whereas classical studies of microbiology historically focused on various anthropocentric sub-fields (such as fermented foods or commensals and pathogens of crop plants, livestock and humans), addressing key biological questions via astrobiological approaches can further our understanding of all life on Earth. We highlight potential implications of this approach through the articles in this Environmental Microbiology special issue 'Ecophysiology of Extremophiles'. They report on the microbiology of places/processes including low-temperature environments and chemically diverse saline- and hypersaline habitats; aspects of sulphur metabolism in hypersaline lakes, dysoxic marine waters, and thermal acidic springs; biology of extremophile viruses; the survival of terrestrial extremophiles on the surface of Mars; biological soils crusts and rock-associated microbes of deserts; subsurface and deep biosphere, including a salticle formed within Triassic halite; and interactions of microbes with igneous and sedimentary rocks. These studies, some of which we highlight here, contribute to our understanding of the spatiotemporal reach of Earth'sfunctional biosphere, and the tenacity of terrestrial life. Their findings will help set the stage for future work focused on the constraints for life, and how organisms adapt and evolve to circumvent these constraints.

DNA metabarcoding of forensic mycological samples

Background

DNA metabarcoding and massive parallel sequencing are valuable molecular tools for the characterization of environmental samples. In forensic sciences, the analysis of the sample’s fungal population can be highly informative for the estimation of post-mortem interval, the ascertainment of deposition time, the identification of the cause of death, or the location of buried corpses. Unfortunately, metabarcoding data analysis often requires strong bioinformatic capabilities that are not widely available in forensic laboratories.

Results

The present paper describes the adoption of a user-friendly cloud-based application for the identification of fungi in typical forensic samples. The samples have also been analyzed through the QIIME pipeline, obtaining a relevant data concordance on top genus classification results (88%).

Conclusions

The availability of a user-friendly application that can be run without command line activities will increase the popularity of metabarcoding fungal analysis in forensic samples.

The Mentalized Affectivity Scale (MAS): Development and validation of the Italian version

This study proposes a psychometric validation of the Italian version of the Mentalized Affectivity Scale (MAS) developed by Greenberg and colleagues in 2017. The mentalized affectivity construct integrates mentalization ability in the process of emotional regulation. An adult sample (N = 506) completed the 60-items MAS online version. In contrast to the three-factor structure of the original version, the Italian context confirmatory and exploratory factor analyses with splitted sample (CFA = 258; EFA = 248) revealed a five-factor structure. The hierarchically structured MAS factors are: Emotional Processing (being able to process emotion in situations); Expressing Emotions (talking and knowing emotions); Identifying Emotions (awareness of emotions); Control Processing (to control emotional reactions and expression), and Autobiographical Memory (related to childhood experiences). We also verified the convergent validity and reliability of the Italian version of the MAS by correlating the above five factors with measures of emotion regulation and reflective functioning. Moreover, we analyzed the relationships among the factors of the MAS, personality measures and well-being indexes, such as life satisfaction and self-efficacy: The new 35-item MAS scale showed robust correlations with all the tested constructs. Our results confirm that the MAS is a useful measure to assess mentalized affectivity, with the Italian version showing a more complex structure than the original English one, thus enriching the literature about mentalization.

Artemisinin Derivatives with Antimelanoma Activity Show Inhibitory Effect against Human DNA Topoisomerase 1

Artesunic acid and artemisinin are natural substances with promiscuous anticancer activity against different types of cancer cell lines. The mechanism of action of these compounds is associated with the formation of reactive radical species by cleavage of the sesquiterpene pharmacophore endoperoxide bridge. Here we suggested topoisomerase 1 as a possible molecular target for the improvement of the anticancer activity of these compounds. In this context, we report that novel hybrid and dimer derivatives of artesunic acid and artemisinin, bearing camptothecin and SN38 as side-chain biological effectors, can inhibit growth of yeast cells overexpressing human topoisomerase 1 and its enzymatic activity in vitro. These derivatives showed also anticancer activity in melanoma cell lines higher than camptothecin and paclitaxel. In silico molecular docking calculations highlighted a common binding mode for the novel derivatives, with the sesquiterpene lactone scaffold being located near the traditional recognition site for camptothecin, while the bioactive side-chain effector laid in the camptothecin cleft.

The COP9 signalosome mediates the Spt23 regulated fatty acid desaturation and ergosterol biosynthesis

The COP9 signalosome (CSN) is a conserved eukaryotic complex, essential for vitality in all multicellular organisms and critical for the turnover of key cellular proteins through catalytic and non-catalytic activities. Saccharomyces cerevisiae is a powerful model organism for studying fundamental aspects of the CSN complex, since it includes a conserved enzymatic core but lacks non-catalytic activities, probably explaining its non-essentiality for life. A previous transcriptomic analysis of an S. cerevisiae strain deleted in the CSN5/RRI1 gene, encoding to the CSN catalytic subunit, revealed a downregulation of genes involved in lipid metabolism. We now show that the S. cerevisiae CSN holocomplex is essential for cellular lipid homeostasis. Defects in CSN assembly or activity lead to decreased quantities of ergosterol and unsaturated fatty acids (UFA); vacuole defects; diminished lipid droplets (LDs) size; and to accumulation of endoplasmic reticulum (ER) stress. The molecular mechanism behind these findings depends on CSN involvement in upregulating mRNA expression of SPT23. Spt23 is a novel activator of lipid desaturation and ergosterol biosynthesis. Our data reveal for the first time a functional link between the CSN holocomplex and Spt23. Moreover, CSN-dependent upregulation of SPT23 transcription is necessary for the fine-tuning of lipid homeostasis and for cellular health.

Statins interfere with the attachment of S. cerevisiae mtDNA to the inner mitochondrial membrane

The 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme of the mevalonate pathway for the synthesis of cholesterol in mammals (ergosterol in fungi), is inhibited by statins, a class of cholesterol lowering drugs. Indeed, statins are in a wide medical use, yet statins treatment could induce side effects as hepatotoxicity and myopathy in patients. We used Saccharomyces cerevisiae as a model to investigate the effects of statins on mitochondria. We demonstrate that statins are active in S.cerevisiae by lowering the ergosterol content in cells and interfering with the attachment of mitochondrial DNA to the inner mitochondrial membrane. Experiments on murine myoblasts confirmed these results in mammals. We propose that the instability of mitochondrial DNA is an early indirect target of statins.

The hypoxic transcription factor KlMga2 mediates the response to oxidative stress and influences longevity in the yeast Kluyveromyces lactis

Hypoxia is defined as the decline of oxygen availability, depending on environmental supply and cellular consumption rate. The decrease in O2 results in reduction of available energy in facultative aerobes. The response and/or adaptation to hypoxia and other changing environmental conditions can influence the properties and functions of membranes by modifying lipid composition. In the yeast Kluyveromyces lactis, the KlMga2 gene is a hypoxic regulatory factor for lipid biosynthesis—fatty acids and sterols—and is also involved in glucose signaling, glucose catabolism and is generally important for cellular fitness.

In this work we show that, in addition to the above defects, the absence of the KlMGA2 gene caused increased resistance to oxidative stress and extended lifespan of the yeast, associated with increased expression levels of catalase and SOD genes. We propose that KlMga2 might also act as a mediator of the oxidative stress response/adaptation, thus revealing connections among hypoxia, glucose signaling, fatty acid biosynthesis and ROS metabolism in K. lactis.

Proteasome lid bridges mitochondrial stress with Cdc53/Cullin1 NEDDylation status

Cycles of Cdc53/Cullin1 rubylation (a.k.a NEDDylation) protect ubiquitin-E3 SCF (Skp1-Cullin1-F-box protein) complexes from self-destruction and play an important role in mediating the ubiquitination of key protein substrates involved in cell cycle progression, development, and survival. Cul1 rubylation is balanced by the COP9 signalosome (CSN), a multi-subunit derubylase that shows 1:1 paralogy to the 26S proteasome lid. The turnover of SCF substrates and their relevance to various diseases is well studied, yet, the extent by which environmental perturbations influence Cul1 rubylation/derubylation cycles per se is still unclear. In this study, we show that the level of cellular oxidation serves as a molecular switch, determining Cullin1 rubylation/derubylation ratio. We describe a mutant of the proteasome lid subunit, Rpn11 that exhibits accumulated levels of Cullin1-Rub1 conjugates, a characteristic phenotype of csn mutants. By dissecting between distinct phenotypes of rpn11 mutants, proteasome and mitochondria dysfunction, we were able to recognize the high reactive oxygen species (ROS) production during the transition of cells into mitochondrial respiration, as a checkpoint of Cullin1 rubylation in a reversible manner. Thus, the study adds the rubylation cascade to the list of cellular pathways regulated by redox homeostasis.

A role for microbial selection in frescoes' deterioration in Tomba degli Scudi in Tarquinia, Italy

Mural paintings in the hypogeal environment of the Tomba degli Scudi in Tarquinia, Italy, show a quite dramatic condition: the plaster mortar lost his cohesion and a white layer coating is spread over almost all the wall surfaces. The aim of this research is to verify if the activity of microorganisms could be one of the main causes of deterioration and if the adopted countermeasures (conventional biocide treatments) are sufficient to stop it. A biocide treatment of the whole environment has been carried out before the conservative intervention and the tomb has been closed for one month. When the tomb was opened again, we sampled the microorganisms present on the frescoes and we identified four Bacillus species and one mould survived to the biocide treatment. These organisms are able to produce spores, a highly resistant biological form, which has permitted the survival despite the biocide treatment. We show that these Bacillus strains are able to produce calcium carbonate and could be responsible for the white deposition that was damaging and covering the entire surface of the frescoes. Our results confirm that the sanitation intervention is non always resolutive and could even be deleterious in selecting harmful microbial communities.

Biological Dual-Use Research and Synthetic Biology of Yeast

In recent years, the publication of the studies on the transmissibility in mammals of the H5N1 influenza virus and synthetic genomes has triggered heated and concerned debate within the community of scientists on biological dual-use research; these papers have raised the awareness that, in some cases, fundamental research could be directed to harmful experiments, with the purpose of developing a weapon that could be used by a bioterrorist. Here is presented an overview regarding the dual-use concept and its related international agreements which underlines the work of the Australia Group (AG) Export Control Regime. It is hoped that the principles and activities of the AG, that focuses on export control of chemical and biological dual-use materials, will spread and become well known to academic researchers in different countries, as they exchange biological materials (i.e. plasmids, strains, antibodies, nucleic acids) and scientific papers. To this extent, and with the aim of drawing the attention of the scientific community that works with yeast to the so called Dual-Use Research of Concern, this article reports case studies on biological dual-use research and discusses a synthetic biology applied to the yeast Saccharomyces cerevisiae, namely the construction of the first eukaryotic synthetic chromosome of yeast and the use of yeast cells as a factory to produce opiates. Since this organism is considered harmless and is not included in any list of biological agents, yeast researchers should take simple actions in the future to avoid the sharing of strains and advanced technology with suspicious individuals.

Screening of freshwater and seawater microalgae strains in fully controlled photobioreactors for biodiesel production

Strain selection is one of the primary hurdles facing cost-effective microalgal biodiesel production. Indeed, the strain used affects both upstream and downstream biodiesel production processes. This study presents a screening procedure that considers the most significant criteria in microalgal biodiesel production including TAG production and wet extraction and recovery of TAGs. Fourteen freshwater and seawater strains were investigated. Large variation was observed between the strains in all the screening criteria. The overall screening procedure ultimately led to the identification of Parachlorella kessleri UTEX2229 and Nannochloropsis gaditana CCMP527 as the best freshwater and seawater strains, respectively. They featured the largest areal TAG productivity equal to 2.7×10(-3) and 2.3×10(-3)kgm(-2)d(-1), respectively. These two strains also displayed encouraging cell fragility in a high pressure bead milling process with 69% and 98% cell disruption at 1750bar making them remarkable strains for TAG extraction in wet environment.

Functional roles of the fatty acid desaturases encoded by KlOLE1, FAD2 and FAD3 in the yeast Kluyveromyces lactis

Functional properties of cell membranes depend on their composition, particularly on the relative amount of saturated, unsaturated and polyunsaturated fatty acids present in the phospholipids. The aim of this study was to investigate the effect of cell membrane composition on cell fitness, adaptation and stress response in Kluyveromyces lactis. To this purpose, we have deleted the genes FAD2 and FAD3 encoding Δ12 and ω3 desaturases in Kluyveromyces lactis, thus generating mutant strains with altered fatty acid composition of membranes. These strains were viable and able to grow in stressing conditions like hypoxia and low temperature. Deletion of the Δ9 desaturase-encoding gene KlOLE1 resulted in lethality, suggesting that this enzyme has an essential role in this yeast. Transcription of the desaturase genes KlOLE1, FAD2 and FAD3 and cellular localization of the corresponding enzymes, have been studied under hypoxia and cold stress. Our findings indicate that expression of these desaturase genes and membrane composition were modulated by hypoxia and temperature stress, although the changes induced by these and other assayed conditions did not dramatically affect the general cellular fitness.

Yeast as a tool to select inhibitors of the cullin deneddylating enzyme Csn5

The CSN complex plays a key role in various cellular pathways: through a metalloprotease activity of its Csn5 deneddylating enzyme, it regulates the activity of Cullin-RING ligases (CRLs). Indeed, Csn5 has been found amplified in many tumors, but, due to its pleiotropic effects, it is difficult to dissect its function and the involvement in cancer progression. Moreover, while growing evidences point to the neddylation function as a good target for drug development; specific inhibitors have not yet been developed for the CSN. Here, we propose the yeast Saccharomyces cerevisiae as a model system to screen libraries of small molecules as inhibitors of cullins deneddylation, taking advantage of the unique feature of this organism to survive without a functional CSN5 gene and to accumulate a fully neddylated cullin substrate. By combining molecular modeling and simple genetic tools, we were able to identify two small molecular fragments as selective inhibitors of Csn5 deneddylation function.

Optimization of bead milling parameters for the cell disruption of microalgae: process modeling and application to Porphyridium cruentum and Nannochloropsis oculata

A study of cell disruption by bead milling for two microalgae, Nannochloropsis oculata and Porphyridium cruentum, was performed. Strains robustness was quantified by high-pressure disruption assays. The hydrodynamics in the bead mill grinding chamber was studied by Residence Time Distribution modeling. Operating parameters effects were analyzed and modeled in terms of stress intensities and stress number. RTD corresponded to a 2 CSTR in series model. First order kinetics cell disruption was modeled in consequence. Continuous bead milling was efficient for both strains disruption. SI-SN modeling was successfully adapted to microalgae. As predicted by high pressure assays, N. oculata was more resistant than P. cruentum. The critical stress intensity was twice more important for N. oculata than for P. cruentum. SI-SN modeling allows the determination of operating parameters minimizing energy consumption and gives a scalable approach to develop and optimize microalgal disruption by bead milling.

Unsaturated fatty acids-dependent linkage between respiration and fermentation revealed by deletion of hypoxic regulatory KlMGA2 gene in the facultative anaerobe-respiratory yeast Kluyveromyces lactis

In the yeast Kluyveromyces lactis, the inactivation of structural or regulatory glycolytic and fermentative genes generates obligate respiratory mutants which can be characterized by sensitivity to the mitochondrial drug antimycin A on glucose medium (Rag(-) phenotype). Rag(-) mutations can occasionally be generated by the inactivation of genes not evidently related to glycolysis or fermentation. One such gene is the hypoxic regulatory gene KlMGA2. In this work, we report a study of the many defects, in addition to the Rag(-) phenotype, generated by KlMGA2 deletion. We analyzed the fermentative and respiratory metabolism, mitochondrial functioning and morphology in the Klmga2Δ strain. We also examined alterations in the regulation of the expression of lipid biosynthetic genes, in particular fatty acids, ergosterol and cardiolipin, under hypoxic and cold stress and the phenotypic suppression by unsaturated fatty acids of the deleted strain. Results indicate that, despite the fact that the deleted mutant strain had a typical glycolytic/fermentative phenotype and KlMGA2 is a hypoxic regulatory gene, the deletion of this gene generated defects linked to mitochondrial functions suggesting new roles of this protein in the general regulation and cellular fitness of K. lactis. Supplementation of unsaturated fatty acids suppressed or modified these defects suggesting that KlMga2 modulates membrane functioning or membrane-associated functions, both cytoplasmic and mitochondrial.

The human SLC25A33 and SLC25A36 genes of solute carrier family 25 encode two mitochondrial pyrimidine nucleotide transporters

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family, many of which have been shown to transport inorganic anions, amino acids, carboxylates, nucleotides, and coenzymes across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. Here two members of this family, SLC25A33 and SLC25A36, have been thoroughly characterized biochemically. These proteins were overexpressed in bacteria and reconstituted in phospholipid vesicles. Their transport properties and kinetic parameters demonstrate that SLC25A33 transports uracil, thymine, and cytosine (deoxy)nucleoside di- and triphosphates by an antiport mechanism and SLC25A36 cytosine and uracil (deoxy)nucleoside mono-, di-, and triphosphates by uniport and antiport. Both carriers also transported guanine but not adenine (deoxy)nucleotides. Transport catalyzed by both carriers was saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. In confirmation of their identity (i) SLC25A33 and SLC25A36 were found to be targeted to mitochondria and (ii) the phenotypes of Saccharomyces cerevisiae cells lacking RIM2, the gene encoding the well characterized yeast mitochondrial pyrimidine nucleotide carrier, were overcome by expressing SLC25A33 or SLC25A36 in these cells. The main physiological role of SLC25A33 and SLC25A36 is to import/export pyrimidine nucleotides into and from mitochondria, i.e. to accomplish transport steps essential for mitochondrial DNA and RNA synthesis and breakdown.

Getting lipids from glycerol: new perspectives on biotechnological exploitation of Candida freyschussii

BACKGROUND

Microbial lipids represent a valuable alternative feedstock for biodiesel production when oleaginous microbes are cultured with inexpensive substrates in processes exhibiting high yield and productivity. In this perspective, crude glycerol is among the most promising raw materials for lipid production, because it is the costless residual of biodiesel production. Thus, cultivation of oleaginous yeasts in glycerol-based media is attracting great interest and natural biodiversity is increasingly explored to identify novel oleaginous species recycling this carbon source for growth and lipid production.

RESULTS

Thirty-three yeasts strains belonging to 19 species were screened for the ability to grow and produce intracellular lipids in a pure glycerol-based medium with high C/N ratio. A minority of them consumed most of the glycerol and generated visible lipid bodies. Among them, Candida freyschussii ATCC 18737 was selected, because it exhibited the highest lipid production and glycerol conversion yield. Lipid production in this strain was positively affected by the increase of C/N ratio, but growth was inhibited by glycerol concentration higher than 40 g/L. In batch cultures, the highest lipid production (4.6 g/L), lipid content of biomass (33% w/w), and lipid volumetric productivity (0.15 g/L/h) were obtained with 40 g/L glycerol, during the course of a 30-h process. Fed-batch cultivation succeeded in preventing substrate inhibition and in achieving a high cell-density culture. The improved lipid production and volumetric productivity reached the remarkable high level of 28 g/L and 0.28 g/L/h, respectively. The lipids accumulated by C. freyschussii ATCC 18737 have similar fatty acid composition of plant oil indicating their potential use as biodiesel feedstock. Calculated physicochemical properties of a biodiesel produced with the lipids from C. freyschussii ATCC 18737 are expected to meet the European and American standards, being equal to those of rapeseed and palm biodiesel.

CONCLUSIONS

C. freyschussii ATCC 18737 could be considered an interesting microorganism for utilization in biofuel industry. Cultivation of this yeast in media containing crude glycerol should be investigated deeper in order to evaluate whether it may find application in the valorization of the waste of biodiesel manufacturing.

An high-throughput in vivo screening system to select H3K4-specific histone demethylase inhibitors

Background

Histone demethylases (HDMs) have a prominent role in epigenetic regulation and are emerging as potential therapeutic cancer targets. The search for small molecules able to inhibit HDMs in vivo is very active but at the present few compounds were found to be specific for defined classes of these enzymes.

Methodology/Principal Findings

In order to discover inhibitors specific for H3K4 histone demethylation we set up a screening system which tests the effects of candidate small molecule inhibitors on a S.cerevisiae strain which requires Jhd2 demethylase activity to efficiently grow in the presence of rapamycin. In order to validate the system we screened a library of 45 structurally different compounds designed as competitive inhibitors of α -ketoglutarate (α-KG) cofactor of the enzyme, and found that one of them inhibited Jhd2 activity in vitro and in vivo. The same compound effectively inhibits human Jumonji AT-Rich Interactive Domain (JARID) 1B and 1D in vitro and increases H3K4 tri-methylation in HeLa cell nuclear extracts (NEs). When added in vivo to HeLa cells, the compound leads to an increase of tri-methyl-H3K4 (H3K4me3) but does not affect H3K9 tri-methylation. We describe the cytostatic and toxic effects of the compound on HeLa cells at concentrations compatible with its inhibitory activity.

Conclusions/Significance

Our screening system is proved to be very useful in testing putative H3K4-specific HDM inhibitors for the capacity of acting in vivo without significantly altering the activity of other important 2-oxoglutarate oxygenases.

Analysis of the rpn11-m1 proteasomal mutant reveals connection between cell cycle and mitochondrial biogenesis

The proteasomal lid subunit Rpn11 is essential for maintaining a correct cell cycle and mitochondrial morphology in Saccharomyces cerevisiae. In this paper, we show that the rpn11-m1 mutant has a peculiar cell cycle defect reminiscent of mutants defective in the FEAR pathway that delay the release of the Cdc14 protein phosphatase from the nucleolus. We analyzed the rpn11-m1 phenotypes and found that overexpression of Cdc14 suppresses all the rpn11-m1 defects, including the mitochondrial ones. Suppression by Cdc14 of the rpn11-m1 mitochondrial morphology defect reveals an uncharacterized connection between mitochondrial and cell cycle events. Interestingly, the overexpression of Cdc14 also partially restores the tubular network in an Δmmm2 strain, which lacks a mitochondrial protein belonging to the complex necessary to anchor the mitochondrion to the actin cytoskeleton. Altogether our findings indicate, for the first time, a cross-talk between the cell cycle and mitochondrial morphology.

Mitochondrial diseases and the role of the yeast models

Nowadays, mitochondrial diseases are recognized and studied with much attention and they cannot be considered anymore as 'rare diseases'. Yeast has been an instrumental organism to understand the genetic and molecular aspects of the many roles of mitochondria within the cells. Thanks to the general conservation of mitochondrial genes and pathways between human and yeast, it can also be used to model some diseases. In this review, we focus on the most recent topics, exemplifying those for which yeast models have been especially valuable.

A nonproteolytic proteasome activity controls organelle fission in yeast

To understand the processes underlying organelle function, dynamics and inheritance, it is necessary to identify and characterize the regulatory components involved. Recently in yeast and mammals, proteins of the membrane fission machinery (Dnm1-Mdv1-Caf4-Fis1 in yeast and DLP1-FIS1 in human) have been shown to have a dual localization on mitochondria and peroxisomes, where they control mitochondrial fission and peroxisome division. Here, we show that whereas vacuole fusion is regulated by the proteasome degradation function, mitochondrial fission and peroxisomal division are not controlled by the proteasome activity but rather depend on a new function of the proteasomal lid subunit Rpn11. Rpn11 was found to regulate the Fis1-dependent fission machinery of both organelles. These findings indicate a unique role of the Rpn11 protein in mitochondrial fission and peroxisomal proliferation that is independent of its role in proteasome-associated deubiquitylation.

Dissection of the carboxyl-terminal domain of the proteasomal subunit Rpn11 in maintenance of mitochondrial structure and function

We have previously demonstrated that the C-terminal part of Rpn11, a deubiquitinating enzyme in the lid of the proteasome, is essential for maintaining a correct cell cycle and normal mitochondrial morphology and function. The two roles are apparently unlinked as the mitochondrial role is mapped to the Carboxy-terminus, whereas the catalytic deubiquitinating activity is found within the N-terminal region. The mitochondrial defects are observed in rpn11-m1 (originally termed mpr1-1), a mutation that generates Rpn11 lacking the last 31 amino acids. No mitochondrial phenotypes are recorded for mutations in the MPN+/JAMM motif. In the present study, we investigated the participation of the last 31 amino acids of the Rpn11 protein by analysis of intragenic revertants and site-specific mutants. We identified a putative alpha-helix necessary for the maintenance of a correct cell cycle and determined that a very short region at the C-terminus of Rpn11 is essential for the maintenance of tubular mitochondrial morphology. Furthermore, we show that expression of the C-terminal part of Rpn11 is able to complement in trans all of the rpn11-m1 mitochondrial phenotypes. Finally, we investigate the mechanisms by which Rpn11 controls the mitochondrial shape and show that Rpn11 may regulate the mitochondrial fission and tubulation processes.

Participation of the proteasomal lid subunit Rpn11 in mitochondrial morphology and function is mapped to a distinct C-terminal domain

Substrates destined for degradation by the 26 S proteasome are labelled with polyubiquitin chains. Rpn11/Mpr1, situated in the lid subcomplex, partakes in the processing of these chains or in their removal from substrates bound to the proteasome. Rpn11 also plays a role in maintaining mitochondrial integrity, tubular structure and proper function. The recent finding that Rpn11 participates in proteasome-associated deubiquitination focuses interest on the MPN+ (Mpr1, Pad1, N-terminal)/JAMM (JAB1/MPN/Mov34) metalloprotease site in its N-terminal domain. However, Rpn11 damaged at its C-terminus (the mpr1-1 mutant) causes pleiotropic effects, including proteasome instability and mitochondrial morphology defects, resulting in both proteolysis and respiratory malfunctions. We find that overexpression of WT (wild-type) RPN8, encoding a paralogous subunit that does not contain the catalytic MPN+ motif, corrects proteasome conformations and rescues cell cycle phenotypes, but is unable to correct defects in the mitochondrial tubular system or respiratory malfunctions associated with the mpr1-1 mutation. Transforming mpr1-1 with various RPN8-RPN11 chimaeras or with other rpn11 mutants reveals that a WT C-terminal region of Rpn11 is necessary, and more surprisingly sufficient, to rescue the mpr1-1 mitochondrial phenotype. Interestingly, single-site mutants in the catalytic MPN+ motif at the N-terminus of Rpn11 lead to reduced proteasome-dependent deubiquitination connected with proteolysis defects. Nevertheless, these rpn11 mutants suppress the mitochondrial phenotypes associated with mpr1-1 by intragene complementation. Together, these results point to a unique role for the C-terminal region of Rpn11 in mitochondrial maintenance that may be independent of its role in proteasome-associated deubiquitination.

Interleukin-13 in systemic sclerosis: relationship to nailfold capillaroscopy abnormalities

The aim of this study was to investigate whether interleukin-13 (IL-13) serum levels correlate to different nailfold capillaroscopy (NC) findings in patients with systemic sclerosis (SSc). IL-13 serum levels were measured using an ELISA method. The following NC abnormalities were considered: the presence of giant loops, haemorrhages, loss of capillaries, disorganisation of the vascular array, ramified/bushy capillaries and sludging of blood. A semiquantitative rating scale was adopted to score these changes, as well as a rating system for avascular areas and three morphological NC patterns ('early', 'active' and 'late'). Mean capillary density was determined by counting the total number of capillaries in a 1 mm length, and the arterial and venous diameters of the capillary as well as the total loop diameter were measured. In SSc patients IL-13 serum levels were significantly higher than in controls ( P < 00.1), whereas in patients with ( n=8) and without ( n=24) abnormal IL-13 serum levels (>17 pg/ml) the comparison of the NC features showed significantly relevant differences concerning a more frequent 'active' NC pattern ( P < 0.02), the presence of haemorrhages ( P < 0.0037) and sludging of blood ( P < 0.038), as well as larger total loop ( P < 0.036) and arterial ( P < 0.03) diameters, in those patients with elevated IL-13 serum levels. The study confirmed that IL-13 serum levels are higher in the sera of patients with SSc, and shows for the first time the significant correlations between this serological finding and some of the main relevant SSc capillaroscopic features, leading us to believe that this cytokine not only seems to sustain the immunological and fibrotic process of SSc, but might have a role in determining the more severe microvascular lesions in this disease.

Relationship of interleukin-12 and interleukin-13 imbalance with class-specific rheumatoid factors and anticardiolipin antibodies in systemic lupus erythematosus

The aim of the study was to evaluate whether the imbalance between IL-12 and IL-13 serum levels, reflecting Th1/Th2 activity, is related to class-specific circulating rheumatoid factors (RF) and anticardiolipin (aCL) antibodies in SLE. Using ELISA we measured serum IL-12, IL-13, RF and aCL antibodies in 73 SLE patients and 20 healthy controls. The determination of IL-12/IL-13 ratio showed that IL-12 levels were above (group A), equal to (group B) or below (group C) IL-13 levels in 71.2%, 15.1% and 13.7% of SLE patients, respectively. IgM-RF levels were significantly higher in group C than in groups A ( P < 0.002) and B ( P < 0.019). Group C had also higher IgM-aCL levels than group A ( P < 0.04). No relationship between IL-12/IL-13 ratio and clinical or other laboratory parameters was found. It was concluded that the increased levels of both IgM-RF and IgM-aCL in patients with prevalent Th2 activity suggest that the predominance of Th2 over Th1 could drive autoantibody production in SLE patients.

Nucleo-mitochondrial interactions in Saccharomyces cerevisiae: characterization of a nuclear gene suppressing a defect in mitochondrial tRNA(Asp) processing

We utilized the heat-sensitive mutant strain (Ts932), bearing a mutation at position 61 in the mitochondrial tRNA(Asp) gene, to identify nuclear genes involved in tRNA biogenesis; this mutant is defective in 3'-end processing and consequently in the production of mature mitochondrial tRNA(Asp). We transformed this strain with a yeast nuclear library and we isolated among other suppressors, an unknown, non-essential gene (called SMM1, corresponding to open reading frame YNR015w), which restored the growth on glycerol and a normal amount of processed tRNA(Asp) in the mutant. The gene contains a domain highly conserved in evolution from bacteria to human and its product has been recently shown to have dihydrouridine synthase activity.

The yeast counterparts of human 'MELAS' mutations cause mitochondrial dysfunction that can be rescued by overexpression of the mitochondrial translation factor EF-Tu

We have taken advantage of the similarity between human and yeast (Saccharomyces cerevisiae) mitochondrial tRNA(Leu)(UUR), and of the possibility of transforming yeast mitochondria, to construct yeast mitochondrial mutations in the gene encoding tRNA(Leu)(UUR) equivalent to the human A3243G, C3256T and T3291C mutations that have been found in patients with the neurodegenerative disease MELAS (for mitochondrial 'myopathy, encephalopathy, lactic acidosis and stroke-like episodes'). The resulting yeast cells (bearing the equivalent mutations A14G, C26T and T69C) were defective for growth on respiratory substrates, exhibited an abnormal mitochondrial morphology, and accumulated mitochondrial DNA deletions at a very high rate, a trait characteristic of severe mitochondrial defects in protein synthesis. This effect was specific at least in the pathogenic mutation T69C, because when we introduced A or G instead of C, the respiratory defect was absent or very mild. All defective phenotypes returned to normal when the mutant cells were transformed by multicopy plasmids carrying the gene encoding the mitochondrial elongation factor EF-Tu. The ability to create and analyse such mutated strains and to select correcting genes should make yeast a good model for the study of tRNAs and their interacting partners and a practical tool for the study of pathological mutations and of tRNA sequence polymorphisms.

[The role of interleukin-12 in immune-mediated rheumatic diseases]

OBJECTIVE

IL-12 is a proinflammatory cytokine produced by different antigen presenting cells. It has been shown to exert a critical role in inducing Th1 phenotype, thus initiating cell-mediated immune responses, but the significance of IL-12 in rheumatic diseases is not clear. Aim of the study was to determine IL-12 serum levels in immune rheumatic diseases and to analyse the relationship of this cytokine with main clinical and laboratory parameters.

METHODS

We analysed, by ELISA, serum IL-12 levels in 114 patients with SLE, 47 with SS, 32 with SSc, 84 with RA, 138 with PA and in 17 healthy controls. We also examined main clinical and laboratory parameters, including autoantibody profile and clinical indices of disease activity.

RESULTS

IL-12 serum levels were significantly higher in SLE and SS patients respect to controls. IL-12 serum levels were significantly higher in SLE patients compared to those affected by RA, PA and SSc. When we evaluated disease activity in SLE patients, we found significantly higher IL-12 serum levels in subjects with fever or in those without renal involvement, while no correlation was found in the other rheumatic immune diseases.

CONCLUSIONS

These findings suggest that IL-12, modulating cell and humoral immune responses, is involved in the pathogenesis of immune rheumatic diseases, such as SLE and SS.

Mitochondrial effects of the pleiotropic proteasomal mutation mpr1/rpn11: uncoupling from cell cycle defects in extragenic revertants

We have previously characterized a Saccharomyces cerevisiae mutant which contains a mutation in the essential rpn11/mpr1 gene coding for the proteasomal regulatory subunit Rpn11. The mpr1-1 mutation shows the phenotypic characteristics generally associated with proteasomal mutations, such as cell cycle defects and accumulation of polyubiquitinated proteins. However, for the first time, mitochondrial defects have also been found to be a consequence of a mutation in a proteasomal gene (Mol. Biol. Cell 9 (1998) 2917-2931). Since the mutant strain is thermosensitive both on glucose and on glycerol, we searched for revertants in order to shed light on the Rpn11/Mpr1 functions. Spontaneous revertants able to grow on glucose but not on glycerol at 36 degrees C were isolated, and, only from them, revertants able to grow at 36 degrees C on glycerol were selected. Revertants of the two classes were found to be extragenic. The detailed characterization of these extragenic suppressors demonstrates that the phenotypes related to cell cycle defects can be dissociated from those concerned with mitochondrial organization.

Interleukin-13 in autoimmune rheumatic diseases: relationship with the autoantibody profile

OBJECTIVE

Several cytokines play a role in the production of autoantibodies such as RF and ANA by B-lymphocytes; the role of IL-13 in this process has not been previously studied. We investigated the relationship between the serum concentration of this cytokine and circulating autoantibodies.

METHODS

IL-13 serum levels, as well as RF and ANA, were evaluated in 282 patients with autoimmune rheumatic diseases including RA (n=84), SLE (n= 114), SS (n=52) and Scl (n=32).

RESULTS

Serum levels of IL-13 (pg/ml) were significantly higher in patients with RA (p < 0.00003), SLE (p < 0.03), SS (p < 0.0007), or Scl (p < 0.025) compared to controls. IL-13 serum levels correlated with those of RF in RA (p < 0.00001), SLE (p < 0.003) and Scl (p < 0.03). IL-13 levels were higher in RA (p<0.0003), SLE (p<0.005) and Scl (p<0.05) patients with RF than in patients without RF. SS patients with antiSSA/Ro antibodies had significantly higher IL-13 levels than SS patients without this autoantibody (p < 0.04). No statistically significant correlation was found between IL-13 levels and any other antinuclear autoantibody, total immunoglobulin levels or the main clinicalfeatures of each disease.

CONCLUSION

The evidence of higher IL-13 levels in our RA, SLE, SS and Scl patients confirms that this cytokine is involved in the pathogenesis of autoimmune rheumatic diseases. The relationship of this cytokine with RF in RA, SLE and Scl, as well as with antiSSA/ Ro antibody in SS, strengthens the hypothesis that it plays a role in autoantibody production. However, the different autoantibody synthesis by B-cells recognises different pathways depending on the underlying autoimmune disease.

Interleukin 13 in synovial fluid and serum of patients with psoriatic arthritis

OBJECTIVES

To compare the pattern of interleukin (IL) 13 production in synovial fluid (SF) and serum of patients with psoriatic arthritis (PsA) with that in patients with rheumatoid arthritis (RA) and osteoarthritis (OA), investigating its relation to the proinflammatory cytokine IL12.

METHODS

SF and serum IL13 levels were determined in 35 patients with PsA, 36 with RA, and 15 with OA. The main clinical and laboratory variables, including number of painful and/or swollen joints, Ritchie index, morning stiffness, erythrocyte sedimentation rate, level of C reactive protein, level of rheumatoid factor, and SF analysis, were also evaluated.

RESULTS

SF IL13 levels were significantly higher in patients with PsA (p<0.02) or RA (p<0.012) than in patients with OA, with no significant difference between the former two. SF IL12 levels were significantly higher in patients with PsA (p<0.023) than in those with OA. Serum IL13 (p<0.0001) and IL12 (p<0.02) levels were lower in patients with PsA than in those affected by RA. Only patients with PsA had higher IL13 levels in SF than in serum (p<0.002). The IL13 SF/serum ratio was higher in the PsA group than in the group with RA (p<0.005) or OA (p<0.026). SF IL13 levels correlated with serum IL13 levels (p<0.0001) in RA and with SF IL12 levels (p<0.03) in PsA.

CONCLUSIONS

In PsA, there appears to be localised production of IL13, in balance with IL12, in the inflamed joints. The distinct IL13 secretion profiles in PsA, RA, and OA may be related to the clinical pictures, reflecting the different pathogenic mechanisms involved in inflammatory and degenerative joint diseases.

Reintroduction of a characterized Mit tRNA glycine mutation into yeast mitochondria provides a new tool for the study of human neurodegenerative diseases

We report the identification and characterization of a new mutation (ts9) in the Saccharomyces cerevisiae mitochondrial genome, which was first genetically mapped in the tRNAgly region and further identified by means of sequencing as consisting of a G to A transition at position 30 in the tRNA. The mutation causes an almost complete disappearance of mature tRNAgly, while a second mitochondrial mutation with a compensatory C to T change restores it in normal quantities; this points to the importance of the strong bond between bases 30 and 40 of the anticodon stem in the stabilization of the tRNA. In addition to resulting in a clear-cut heat-sensitive phenotype, the ts9 mutation creates a new EcoRV restriction site. Both properties were used as markers to monitor the successful (re) introduction of the mutated allele into a wild-type mitochondrial genome through biolistic transformation. The mutant frequency in the progeny as well as the correct integration of the mutated allele at its proper site demonstrate the feasibility of this method for creating and investigating specific mitochondrial tRNA mutations. The method will provide important applications for the use of yeast as a model system of human mitochondrial pathologies.

Ultrasound measurements at the proximal phalanges in male patients with psoriatic arthritis

Bone ultrasound parameters at the proximal phalanges of the hands were measured in 55 male patients with psoriatic arthritis (PA) (39 with peripheral radiologic involvement and 16 with axial involvement), comparing the findings with those in 16 rheumatoid arthritis (RA) patients, 20 ankylosing spondylitis (AS) patients and 55 age- and sex-matched normal controls. Mean values of amplitude-dependent speed of sound (Ad-SoS) and ultrasound bone profile score (UBPS) were significantly lower in RA (p < 0.001 and p < 1 x 10(-5)) and PA (p < 0.03 and p < 1 x 10(-6)) patients than in controls, while there was no statistically significant difference between AS patients and healthy subjects. Ultrasound parameters showed a significant negative correlation with age in all groups. In each patient group ultrasound values were unrelated either to disease duration or to inflammatory indices such as erythrocyte sedimentation rate and C-reactive protein. Moreover no significant differences were observed between ultrasound parameters of the dominant and the nondominant hand. PA patients with and without axial radiologic changes did not show any differences in ultrasound parameters. However, PA subjects with peripheral involvement only had significantly higher Ad-SoS (p < 0.04) and UBPS (p < 0.04) values than RA patients. PA patients with axial lesions had significantly lower (p < 0.04 and p < 0.01) ultrasound values than AS patients. These findings suggest that PA ultrasound techniques performed at the peripheral level are of value to speculate on bone involvement, although we think that ultrasound measurements cannot yet be recommended for monitoring bone involvement in these patients.

Class specific rheumatoid factors and antiphospholipid syndrome in systemic lupus erythematosus

The relationship of rheumatoid factors (RF) with antiphospholipid syndrome (aPLS) and anticardiolipin antibodies (aCL) has rarely been investigated in systemic lupus erythematosus (SLE). We found IgM-RF, IgG-RF, IgA-RF, IgM-aCL, IgG-aCL, IgA-aCL, respectively, in 35.4%, 35.4%, 33.8%, 23.1%, 23.1%, 20.0% of 65 SLE patients. Class specific RFs were negatively associated (P<0.05) with IgG-aCL. The frequency of definite or probable aPLS according to Alarcon-Segovia classification criteria was significantly (P<0.05) different (8.7% vs 30.9%) in patients with or without IgG-RF. Among the other clinical features of SLE, we found that patients with IgG-RF, compared to patients lacking this autoantibody, showed a lower frequency (P<0.05) of serositis (21.7% vs 52.4%) and hematologic (52. 2% vs 80.9%) disorders. The levels of IgG-RF and IgM-RF negatively correlated with the number of ARA criteria (P<0.05) but not with the indices of diseases activity or damage. Our study shows that in SLE the presence of RFs are not markers of severity of the disease, but the negative association between IgG-RF and IgG-aCL suggests a distinct role of these autoantibodies in the pathology of SLE, whereas the presence of IgG isotype may identify a subset of SLE patients having a lower risk to develop some clinical manifestations such as aPLS.

Comparison of the Health Assessment Questionnaire and Arthritis Impact Measurement Scale in patients with psoriatic arthritis

OBJECTIVE

To determine which of two instruments, the Health Assessment Questionnaire (HAQ) and the Arthritis Impact Measurement Scales (AIMS), was more closely correlated with the main parameters reflecting activity and severity of psoriatic arthritis.

METHODS

Both instruments were administered to 72 consecutive patients with psoriatic arthritis.

RESULTS

Global HAQ and AIMS scores were closely correlated with each other (rs = 0.747; P < 0.00001). AIMS physical function scales--namely physical activity, dexterity, social activity and activities of daily living--were moderately or closely correlated with the main clinical disease activity parameters, most notably morning stiffness of axial joints (rs = 0.271-0.551). Scales measuring psychological status yielded weaker correlations with disease activity parameters (rs = 0.241-0.277) and were also correlated with the visual analog scale score for skin lesion severity. Morning stiffness of peripheral joints was correlated only with two AIMS scales, namely pain (rs = 0.532) and activities of daily living (rs = 0.303). Severity of radiological damage of peripheral and axial joints was most closely correlated with the scales of physical function, most notably physical activity. The global and scale HAQ scores showed moderate to close correlations with the main clinical disease activity parameters, most notably morning stiffness of axial joints. The global HAQ score was also correlated with radiological carpal involvement and with the radiological severity of peripheral joint involvement, whereas only the arising and hygiene scales were (moderately) correlated with the radiological severity of spinal involvement.

CONCLUSION

Although both the HAQ and the AIMS were useful in assessing health status in psoriatic arthritis patients, only the AIMS captured some of the effects of the skin lesions. Our data also suggest that the AIMS may be more effective than the HAQ for evaluating the effect of radiological lesions produced by psoriatic arthritis.

A mutation in a novel yeast proteasomal gene, RPN11/MPR1, produces a cell cycle arrest, overreplication of nuclear and mitochondrial DNA, and an altered mitochondrial morphology

We report here the functional characterization of an essential Saccharomyces cerevisiae gene, MPR1, coding for a regulatory proteasomal subunit for which the name Rpn11p has been proposed. For this study we made use of the mpr1-1 mutation that causes the following pleiotropic defects. At 24 degreesC growth is delayed on glucose and impaired on glycerol, whereas no growth is seen at 36 degreesC on either carbon source. Microscopic observation of cells growing on glucose at 24 degreesC shows that most of them bear a large bud, whereas mitochondrial morphology is profoundly altered. A shift to the nonpermissive temperature produces aberrant elongated cell morphologies, whereas the nucleus fails to divide. Flow cytometry profiles after the shift to the nonpermissive temperature indicate overreplication of both nuclear and mitochondrial DNA. Consistently with the identification of Mpr1p with a proteasomal subunit, the mutation is complemented by the human POH1 proteasomal gene. Moreover, the mpr1-1 mutant grown to stationary phase accumulates ubiquitinated proteins. Localization of the Rpn11p/Mpr1p protein has been studied by green fluorescent protein fusion, and the fusion protein has been found to be mainly associated to cytoplasmic structures. For the first time, a proteasomal mutation has also revealed an associated mitochondrial phenotype. We actually showed, by the use of [rho degrees] cells derived from the mutant, that the increase in DNA content per cell is due in part to an increase in the amount of mitochondrial DNA. Moreover, microscopy of mpr1-1 cells grown on glucose showed that multiple punctate mitochondrial structures were present in place of the tubular network found in the wild-type strain. These data strongly suggest that mpr1-1 is a valuable tool with which to study the possible roles of proteasomal function in mitochondrial biogenesis.

Additional copies of the mitochondrial Ef-Tu and aspartyl-tRNA synthetase genes can compensate for a mutation affecting the maturation of the mitochondrial tRNAAsp

In an attempt to identify new nuclear genes involved in the synthesis and processing of mitochondrial tRNAs, we utilized a multicopy nuclear library to suppress the heat-sensitive phenotype of a Saccharomyces cerevisiae mitochondrial mutant strain. This strain (Ts 932) is defective in the 3'-end processing of the mitochondrial tRNAAsp transcript. The nuclear genes coding for the mitochondrial elongation factor Tuf M and for the mitochondrial aspartyl-tRNA synthetase have been found to restore the temperature-resistant phenotype and to correct the RNA processing defect. Suppression was effective even when the genes were present on a centromeric plasmid.