Die Bedeutung von Alb4 in der Biogenese der Chloroplasten

Mitglieder der evolutionär konservierten Oxa-Proteinfamilie wirken an der korrekten Insertion von integralen Membranproteinen in Bakterien, Mitochondrien und Chloroplasten mit. In den sehr proteinreichen Thylakoidmembranen der Chloroplasten höherer Pflanzen spielt das Oxa-Homolog Alb3 eine essentielle Rolle bei der Integration von LHC-Proteinen und weiteren Komponenten des Photosynthese-Apparates. Im Rahmen dieser Arbeit wurde ein weiteres Protein aus Arabidopsis identifiziert und als neues Mitglied der Oxa-Proteinfamilie beschrieben. Die experimentell gestützte Annotation zeigt, dass das Alb4-Protein eine zentrale 60KD_IMP-Domäne besitzt, welche für die Oxa-Proteine charakteristisch ist. Die Zugehörigkeit zur Oxa-Proteinfamilie konnte funktionell durch die Komplementation einer Hefe-oxa1-Mutante bestätigt werden. Immunologische und fluoreszenzmikroskopische Untersuchungen konnten weiterhin zeigen, dass es sich bei Alb4 um ein chloroplastidäres Protein handelt, welches als integrales Membranprotein in den Thylakoiden lokalisiert ist. Durch die Analyse von T-DNA-Insertions- und RNAi-Linien konnte gezeigt werden, dass eine Reduktion des Alb4-Gehaltes zu vergrößerten und nicht länger linsenförmigen Chloroplasten führt, in denen die Thylakoidmembranen aufgelockerter erscheinen. Ein Verlust der Lebensfähigkeit konnte jedoch nicht beobachtet werden, selbst wenn der Alb4-Gehalt in den Chloroplasten der Pflanzen um mehr als 90% reduziert war. Im Vergleich zu Cyanobakterien besitzt die Thylakoidmembran von Arabidopsis mit Alb4 und Alb3 gleich zwei Oxa-Homologe. Möglicherweise ist nach der Umwandlung des cyanobakteriellen Endosymbionten zu einem eukaryotischen Organell diese Duplizierung nötig geworden, um sowohl die Ausbildung als auch den Erhalt der Thylakoidstruktur zu gewährleisten. Zusätzlich zur Identifizierung von Alb4 konnte durch Transkript-Analysen desweiteren gezeigt werden, dass auch der N-Terminale Teil des ehemaligen Genmodells F21J9.13 (Artemis, nun Alb4 und RWK1) für ein eigenständiges Gen kodiert. Das abgeleitete Protein aus dem N-terminalen Teil, RWK1, ähnelt dem Rezeptor-Teil von pflanzlichen Rezeptor-Kinasen, eine entsprechende Kinase-Domäne fehlt jedoch vollständig. RWK1 kommt in zwei Spleißvarianten vor, der für die meisten eukaryotischen mRNAs typische polyA-Schwanz fehlt jedoch beiden Varianten. RWK1 könnte als neuartiger Rezeptor ein weiteres Glied in der internen Kommunikationskette der Zelle bilden

Finite Element Simulation and Experimental Assessment of Laser Cutting Unidirectional CFRP at Cutting Angles of 45° and 90°

Laser cutting of carbon fibre-reinforced plastics (CFRP) is a promising alternative to traditional manufacturing methods due to its non-contact nature and high automation potential. To establish the process for an industrial application, it is necessary to predict the temperature fields arising as a result of the laser energy input. Elevated temperatures during the cutting process can lead to damage in the composite’s matrix material, resulting in local changes in the structural properties and reduced material strength. To address this, a three-dimensional finite element model is developed to predict the temporal and spatial temperature evolution during laser cutting. Experimental values are compared with simulated temperatures, and the cutting kerf geometry is examined. Experiments are conducted at 45° and 90° cutting angles relative to the main fibre orientation using a 1.1 mm thick epoxy-based laminate. The simulation accurately captures the overall temperature field expansion caused by multiple laser beam passes over the workpiece. The influence of fibre orientation is evident, with deviations in specific temperature data indicating differences between the estimated and real material properties. The model tends to overestimate the ablation rate in the kerf geometry, attributed to mesh resolution limitations. Within the parameters investigated, hardly any expansion of a heat affected zone (HAZ) is visible, which is confirmed by the simulation results

Macroscopic simulation model for laser cutting of carbon fibre reinforced plastics

Laser cutting of carbon fibre reinforced plastics (CFRP) has shown promising potential as an alternative to conventional manufacturing processes. Laser cutting has major benefits of contactless and therefore wear-free machining and high automation potential. The main challenge is to reduce the heat input into the material during the process. Excessive temperatures cause damage within the surrounding matrix material and could locally modify the structural properties of the CFRP. For industrial use it is necessary to be able to predict the resulting temperature fields. To gain knowledge of the temperature distribution during the process, a three-dimensional macroscopic finite element model is developed using ANSYS simulation software. Transient-thermal analyses are performed and the material removal process is implemented via the element-death technique. Simulations are run for a unidirectional composite structure and different cutting speeds. The resulting temperatures are compared to experimental data

High genetic diversity among Mycobacterium tuberculosis complex strains from Sierra Leone

<p>Abstract</p> <p>Background</p> <p>Among tuberculosis (TB) high incidence regions, Sub-Saharan Africa is particularly affected with approx. 1.6 million new cases every year. Besides this dramatic situation, data on the diversity of <it>Mycobacterium tuberculosis </it>complex (MTBC) strains causing this epidemic in this area are only sparsely available. Here we analyzed the population structure of strains from Sierra Leone with a special focus on the prevalence of <it>M. africanum</it>.</p> <p>Results</p> <p>A total of 97 strains isolated from smear positive cases registered for re-treatment in the Western Area and Kenema districts in years 2003/2004 were investigated by susceptibility testing (first line drugs) and molecular typing (IS<it>6110 </it>fingerprinting, spoligotyping, and MIRU-VNTR typing).</p> <p>Among the strains analyzed, 32 were resistant to isoniazid, and 11 were multidrug resistant (at least resistant to isoniazid and rifampin). The population diversity was high with two previously described <it>M. africanum </it>lineages (West African-1, n = 6; West African-2, n = 17) and seven <it>M. tuberculosis </it>lineages (Haarlem, n = 14; LAM, n = 15; EAI, n = 4; Beijing, n = 4; S-type, n = 4, X-type, n = 1; Cameroon, n = 4). Furthermore, two new <it>M. tuberculosis </it>genotypes Sierra Leone-1 (n = 7) and -2 (n = 10) were found. Strain classification according to a 7 bp deletion in pks1/15 revealed that the majority of <it>M. tuberculosis </it>strains belonged to the Euro American lineage (66 out of 74).</p> <p>Conclusion</p> <p>Resistance rates in Sierra Leone have reached an alarming level. The population structure of MTBC strains shows an intriguing diversity raising the question of possible consequences for TB epidemic and for the introduction of new diagnostic tests or treatment strategies in West Africa.</p

Identification of a Danish breast/ovarian cancer family double heterozygote for BRCA1 and BRCA2 mutations

Mutations in the two breast cancer susceptibility genes BRCA1 and BRCA2 are associated with increased risk of breast and ovarian cancer. Patients with mutations in both genes are rarely reported and often involve Ashkenazi founder mutations. Here we report the first identification of a Danish breast and ovarian cancer family heterozygote for mutations in the BRCA1 and BRCA2 genes. The BRCA1 nucleotide 5215G > A/c.5096G > A mutation results in the missense mutation Arg1699Gln, while the BRCA2 nucleotide 859 + 4A > G/c.631 + 4A > G is novel. Exon trapping experiments and reverse transcriptase (RT)–PCR analysis revealed that the BRCA2 mutation results in skipping of exon 7, thereby introducing a frameshift and a premature stop codon. We therefore classify the mutation as disease causing. Since the BRCA1 Arg1699Gln mutation is also suggested to be disease-causing, we consider this family double heterozygote for BRCA1 and BRCA2 mutations

Identification of six new susceptibility loci for invasive epithelial ovarian cancer

Genome-wide association studies (GWAS) have identified 12 epithelial ovarian cancer (EOC) susceptibility alleles. The pattern of association at these loci is consistent in BRCA1 and BRCA2 mutation carriers who are at high risk of EOC. After imputation to 1000 Genomes Project data, we assessed associations of 11 million genetic variants with EOC risk from 15,437 cases unselected for family history and 30,845 controls and from 15,252 BRCA1 mutation carriers and 8,211 BRCA2 mutation carriers (3,096 with ovarian cancer), and we combined the results in a meta-analysis. This new study design yielded increased statistical power, leading to the discovery of six new EOC susceptibility loci. Variants at 1p36 (nearest gene, WNT4), 4q26 (SYNPO2), 9q34.2 (ABO) and 17q11.2 (ATAD5) were associated with EOC risk, and at 1p34.3 (RSPO1) and 6p22.1 (GPX6) variants were specifically associated with the serous EOC subtype, all with P < 5 × 10(-8). Incorporating these variants into risk assessment tools will improve clinical risk predictions for BRCA1 and BRCA2 mutation carriers

Resting cells rely on the DNA helicase component MCM2 to build cilia

Minichromosome maintenance (MCM) proteins facilitate replication by licensing origins and unwinding the DNA double strand. Interestingly, the number of MCM hexamers greatly exceeds the number of firing origins suggesting additional roles of MCMs. Here we show a hitherto unanticipated function of MCM2 in cilia formation in human cells and zebrafish that is uncoupled from replication. Zebrafish depleted of MCM2 develop ciliopathy-phenotypes including microcephaly and aberrant heart looping due to malformed cilia. In non-cycling human fibroblasts, loss of MCM2 promotes transcription of a subset of genes, which cause cilia shortening and centriole overduplication. Chromatin immunoprecipitation experiments show that MCM2 binds to transcription start sites of cilia inhibiting genes. We propose that such binding may block RNA polymerase II-mediated transcription. Depletion of a second MCM (MCM7), which functions in complex with MCM2 during its canonical functions, reveals an overlapping cilia-deficiency phenotype likely unconnected to replication, although MCM7 appears to regulate a distinct subset of genes and pathways. Our data suggests that MCM2 and 7 exert a role in ciliogenesis in post-mitotic tissues

Ассоциативно-семантическая группа как языковая основа концепта

Статья посвящена описанию особой лексико-семантической парадигмы ассоциативно-семантической группы, которая является частью ассоциативно- семантического комплекса и рассматривается как языковая основа концепта. Исследование проведено с применением описательного, структурного и функционального методов.Статтю присвячено опису особливої лексико-семантичної парадигми асоціативно-семантичної групи, яка є частиною асоціативно-семантичного комплексу і являє собою мовну основу концепту. Дослідження проведено із застосуванням описового, структурного та функціонального методів.The particular lexico-semantic paradigm – associative-semantic group (ASG) which is the part of associative-semantic complex (ASC) – is investigated in the article as a linguistic base of concept. Descriptive, structural, and functional methods were used

Genome-wide significant association with seven novel multiple sclerosis risk loci

Objective: A recent large-scale study in multiple sclerosis (MS) using the ImmunoChip platform reported on 11 loci that showed suggestive genetic association with MS. Additional data in sufficiently sized and independent data sets are needed to assess whether these loci represent genuine MS risk factors. Methods: The lead SNPs of all 11 loci were genotyped in 10 796 MS cases and 10 793 controls from Germany, Spain, France, the Netherlands, Austria and Russia, that were independent from the previously reported cohorts. Association analyses were performed using logistic regression based on an additive model. Summary effect size estimates were calculated using fixed-effect meta-analysis. Results: Seven of the 11 tested SNPs showed significant association with MS susceptibility in the 21 589 individuals analysed here. Meta-analysis across our and previously published MS case-control data (total sample size n=101 683) revealed novel genome-wide significant association with MS susceptibility (p<5×10−8) for all seven variants. This included SNPs in or near LOC100506457 (rs1534422, p=4.03×10−12), CD28 (rs6435203, p=1.35×10−9), LPP (rs4686953, p=3.35×10−8), ETS1 (rs3809006, p=7.74×10−9), DLEU1 (rs806349, p=8.14×10−12), LPIN3 (rs6072343, p=7.16×10−12) and IFNGR2 (rs9808753, p=4.40×10−10). Cis expression quantitative locus effects were observed in silico for rs6435203 on CD28 and for rs9808753 on several immunologically relevant genes in the IFNGR2 locus. Conclusions: This study adds seven loci to the list of genuine MS genetic risk factors and further extends the list of established loci shared across autoimmune diseases