Chapter GIS and ex situ Plant Conservation

Electronics engineerin

The role of Sn in the oxidation of Nb silicide based alloys

Aero-engine materials used in critical components must have acceptable oxidation behaviour at the temperatures of service. Niobium silicide based alloys have the potential to replace Ni based superalloys in future aero-engines owing to their lower densities, higher melting points and balance of properties. Niobium silicide based alloys must have inherent oxidation resistance to survive in case of coating failure . Great advances have been made towards improving the oxidation behaviour of developmental Nb silicide based alloys. Tin was reported [1, 2] to improve oxidation and subsequent research [3, 4] confirmed that Sn as an alloying addition contributes towards suppressing pest oxidation and is an essential alloying addition for suppressing the spallation of scale at high temperatures [5]. Evidence for the enrichment of the microstructure below the alloy/scale interface with Sn was provided for the first time by the group [3, 4]. “How Sn manages to deliver” better oxidation behaviour in Nb silicide based alloys was not understood. In the last “beyond the Ni superalloys” ECI conference some preliminary results were presented in a poster addressing this point. This presentation will be based on the results of recently completed systematic experimental and modelling research of model alloys and ternary systems to show how Sn affects microstructure and oxidation behaviour. Particular emphasis will be given to the links between phase stability, volume fraction and distributions of key intermetallic phases in the microstructure of Sn containing Nb silicide based alloys and their oxidation at 800 and 1200 oC. The role of Sn for the microstructure at the alloy/scale interface will be discussed

Presence of antiphospholipid antibodies is associated with increased implantation failure following in vitro fertilization technique and embryo transfer: A systematic review and meta-analysis

PURPOSE: A systematic review and meta-analysis was conducted comparing the presence of anti-phospholipid (anti-PL) antibodies between women of reproductive age, without diagnosis of antiphospholipid syndrome, who experienced at least two implantation failures following in vitro fertilization and embryo transfer (IVF-ET), and either women who had a successful implantation after IVF-ET or women with at least one successful spontaneous pregnancy or unselected healthy fertile women with no history of IVF-ET. METHODS: Systematic search of the literature and meta-analysis of the relevant studies studying presence of antiphospholipid antibodies in women experiencing at least two implantation failures in IVF-ET as compared to either women who had a successful implantation after IVF-ET or/and women with at least one successful spontaneous pregnancy or unselected healthy fertile women with no history of IVF-ET. Six hundred ninety-four published reports were retrieved; 17 of them fulfilled the inclusion criteria set. RESULTS: Presence of either any type of anti-phospholipid or anticardiolipin antibodies or lupus-anticoagulant in women experiencing at least two implantation failures in IVF-ET was associated with increased implantation failure compared to women who had a successful implantation after IVF-ET (relative risk, RR: 3.06, 5.06 and 5.81, respectively). Presence of either anticardiolipin or lupus-anticoagulant or anti-beta(2) glycoprotein-I or anti-phosphatidylserine antibodies in women experiencing at least two implantation failures in IVF-EΤ was associated with increased implantation failure compared to unselected healthy fertile women with no history of IVF-ET (RR:13.92, 6.37, 15.04 and 164.58, respectively). CONCLUSION: The prevalence of antiphospholipid antibodies, particularly that of anti-beta(2) glycoprotein-I and anti-phosphatidylserine antibodies, in women experiencing at least two implantation failures in IVF-ET without diagnosis of antiphospholipid syndrome is significantly greater than either in women who had a successful implantation after IVF-ET or women with at least one successful spontaneous pregnancy or unselected healthy fertile women with no history of IVF-ET. TRIAL REGISTRATION NUMBER: PROSPERO ID: CRD4201808145

Comparative genomics among dairy strains of Streptococcus thermophilus

Microorganisms like lactic acid bacteria are employed for the biotransformation of raw materials into fermented foods. Fermented foods have increased nutritional value and shelf life as well as improved organoleptic characteristics compared to the raw materials. Interestingly, there are several genera within lactic acid bacteria that are considered to be important for food fermentations including the Streptococcus genus. However, only Streptococcus thermophilus is used as a starter culture. Streptococcus thermophilus has been adapted to milk and dairy products through a reductive evolution process that has led to the loss of typical streptococcal pathogenictraits. In this work we present the comparative genomic analysis among the recently sequenced genome of S. thermophilus ACA-DC 29 is olated from yogurt and the existing seven complete genome sequences of S. thermophilus. Full chromosome alignments revealed a high degree of synteny among the different strains although strain specific differences could also be observed. The pangenome of the eight strains was comprised of approximately 2,300 genes. Concerning the ACA-DC 29 strain, the majority of genes was distributed in the core and the accessory genomes. We also identified a significant percentage of unique genes, i.e. approximately 250, involved in various biological processes. Further analysis of these unique genes revealed that several of them may have been acquired through horizontal gene transfer. We also predicted five potential antimicrobial peptides and two CRISPR systems, which may confer resistance against phages. Overall, our analysis provides useful insights into the technological potential of the ACA-DC 29 strain

Comparative analysis of pSMA198 found in Streptococcus macedonicus ACA-DC 198, the first streptococcal plasmid of the pCI305/pWV02 family of theta-replicating replicons

Here we analyze pSMA198, the first plasmid isolated from Streptococcus macedonicus ACA-DC 198, and we attempt to clarify the route of its original acquisition. Based on the similarity profiles of the plasmid’s replication initiation protein (Rep) and its origin of replication (ori), pSMA198 was found to be a novel member of the pCI305/pWV02 family of theta-replicating plasmids. The pCI305/pWV02 family consists of plasmids of narrow host range that are mainly found in lactococcal species. Comparative analysis of the pSMA198 revealed a high degree of similarity with plasmids pSK11b, pVF22 and pIL5 over its replication backbone, its mobilization backbone and most of its length, respectively. All these three plasmids have been isolated from Lactococcus lactis strains deriving from milk or its products supporting that S. macedonicus acquired pSMA198 from the latter species and that this acquisition took place in the dairy environment. Both pSMA198 and the chromosome of S. macedonicus exhibit a high degree of pseudogenes, indicating that they must have evolved under the same gene decay processes. Furthermore, we were able to determine chromosomal regions that may have originated from pSMA198, also supporting a long co-existence of the two replicons. In addition, pSMA198 is carried by S. macedonicus strains segregated in five different genotypes by pulsed-field gel electrophoresis (PFGE), showing that pSMA198’s acquisition is not a recent event. We propose that our overall analysis of pSMA198 points towards the habituation of S. macedonicus ACA-DC 198 to the dairy environment

Characterization of plasmid pSMA198 found in Streptococcus macedonicus ACA-DC 198 supports the relation of the species to the milk environment

Background: Streptococcus macedonicus is an intriguing streptococcal species whose most frequent source of isolation is fermented foods similarly to Streptococcus thermophilus. During the genome sequencing of S. macedonicus ACA-DC 198 a plasmid was identified. Objectives: To analyse pSMA198, the first plasmid isolated from S. macedonicus and to shed light onto its acquisition path. Methods: Similarity searches of nucleotide and protein sequences, comparative analysis of whole plasmid sequences and phylogenetic analysis were performed using the appropriate bioinformatics tools. Methods: Based on the similarity profiles of the plasmid’s replication initiation protein (Rep) and its origin of replication (ori), pSMA198 belongs to the narrow host range pCI305/pWV02 family found primarily in lactococci and it is the first such plasmid to be reported in streptococci. Comparative analysis of the pSMA198 over its ori, origin of transfer (oriT) or entire length revealed a high degree of similarity with plasmids pSK11b, pVF22 and pIL5, respectively, all isolated from Lactococcus lactis strains from milk or milk products. Phylogenetic analysis of the pSMA198 Rep showed that the vast majority of closely related proteins derive from lactococcal dairy isolates. Conclusions: Our findings demonstrate that S. macedonicus ACA-DC 198 acquired most probably plasmid pSMA198 from L. lactis during an ancestral genetic exchange event that took place in milk or dairy products. Based on our analysis we provide the first molecular and evolutionary evidence for the habituation of S. macedonicus to the dairy environment