The secondary structures of the Xenopus laevis and human mitochondrial small ribosomal subunit RNA are similar

AbstractExtensive corrections of the nucleotide sequence of the Xenopuslaevis mitochondrial small ribosomal subunit RNA gene [Roe et al. (1985) J. Biol. Chem. 260, 9759-9774] are reported. We found an additional fragment of 142 nucleotides and describe 25 nucleotide differences scattered in the gene. The nucleotide sequence of the X. laevis mitochondrial 12 S rRNA gene presents 80% homology with that of the same gene of bovine mitochondrion. We propose a new secondary structure for the product of the X. laevis gene. Contrary to the finding of Roe et al., we observed the same general organization of stems and loops as for the human mitochondrial 12 S rRNA gene product. On the other hand, the structural homology observed between the mitochondrial and cytoplasmic small subunit rRNAs of X. laevis appears much lower. These results strongly suggest that animal vertebrate mitochondrial DNAs have followed the same evolutionary pathway

Ontogenic Appearance of MHC Class I (B-F) Antigens During Chicken Embryogenesis

Expression of chicken MHC class (B-F) antigens during ontogeny was determined by binding of anticlass antibody and appearance of B-F transcripts by Northern blotting in chicken organs during embryogenesis until 2 weeks after hatching. MHC class transcripts first become detectable in day 6.5 of embryogenesis. B-F cell-surface expression first becomes detectable in hemopoietic organs by day 10‑12 of embryogenesis and somewhat later in nonhemopoietic organs. Flow cytometry analysis of hemopoietic cells throughout embryogenesis revealed B-Fhi and B-F1 cell populations. The percentage of B-F cells in spleen and bone marrow decreased around hatching, which could reflect either cell flows in these organs during this period or the sensitivity of hemopoietic cells to hatching stress

Genomics of high molecular weight plasmids isolated from an on-farm biopurification system

The use of biopurification systems (BPS) constitutes an efficient strategy to eliminate pesticides from polluted wastewaters from farm activities. BPS environments contain a high microbial density and diversity facilitating the exchange of information among bacteria, mediated by mobile genetic elements (MGEs), which play a key role in bacterial adaptation and evolution in such environments. Here we sequenced and characterized high-molecular-weight plasmids from a bacterial collection of an on-farm BPS. The high-throughput-sequencing of the plasmid pool yielded a total of several Mb sequence information. Assembly of the sequence data resulted in six complete replicons. Using in silico analyses we identified plasmid replication genes whose encoding proteins represent 13 different Pfam families, as well as proteins involved in plasmid conjugation, indicating a large diversity of plasmid replicons and suggesting the occurrence of horizontal gene transfer (HGT) events within the habitat analyzed. In addition, genes conferring resistance to 10 classes of antimicrobial compounds and those encoding enzymes potentially involved in pesticide and aromatic hydrocarbon degradation were found. Global analysis of the plasmid pool suggest that the analyzed BPS represents a key environment for further studies addressing the dissemination of MGEs carrying catabolic genes and pathway assembly regarding degradation capabilities.Acknowledgements: This work was supported by the European Commission’s 7th Framework Programme (project Metaexplore 222625), the National Scientific and Technical Research Council of Argentina (Consejo Nacional de Investigaciones Científicas y Técnicas—CONICET, Argentina) and Ministry of Science Technology and Productive Innovation (Ministerio de Ciencia Tecnolología e Innovación Productiva—MinCyT, Argentina), projects PICT2013-0113, PICT2012-518 and PICT 2012-1719). MCM, FJA were supported by fellowships from CONICET. MFDP, MP, ML, GTT and AL are researchers at CONICET. The bioinformatics support of the BMBF-funded project (grant 031A533) within the German Network for Bioinformatics Infrastructure (de.NBI) is gratefully acknowledged. Work in FdlC group was supported by grant “Plasmid Offensive” BFU2014-55534-C2-1-P from Ministerio de Economía y Competitividad (MINECO, Spain), and Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015/0019) from Instituto de Salud Carlos III (Spain)-co-financed by European Development Regional Fund. The authors are grateful to Paula Giménez and Silvana Tongiani for excellent technical assistance

T4-Related Bacteriophage LIMEstone Isolates for the Control of Soft Rot on Potato Caused by ‘Dickeya solani’

The bacterium ‘Dickeya solani’, an aggressive biovar 3 variant of Dickeya dianthicola, causes rotting and blackleg in potato. To control this pathogen using bacteriophage therapy, we isolated and characterized two closely related and specific bacteriophages, vB_DsoM_LIMEstone1 and vB_DsoM_LIMEstone2. The LIMEstone phages have a T4-related genome organization and share DNA similarity with Salmonella phage ViI. Microbiological and molecular characterization of the phages deemed them suitable and promising for use in phage therapy. The phages reduced disease incidence and severity on potato tubers in laboratory assays. In addition, in a field trial of potato tubers, when infected with ‘Dickeya solani’, the experimental phage treatment resulted in a higher yield. These results form the basis for the development of a bacteriophage-based biocontrol of potato plants and tubers as an alternative for the use of antibiotics

Clonal Structure of Rapid-Onset MDV-Driven CD4+ Lymphomas and Responding CD8+ T Cells

Lymphoid oncogenesis is a life threatening complication associated with a number of persistent viral infections (e.g. EBV and HTLV-1 in humans). With many of these infections it is difficult to study their natural history and the dynamics of tumor formation. Marek's Disease Virus (MDV) is a prevalent α-herpesvirus of poultry, inducing CD4+ TCRαβ+ T cell tumors in susceptible hosts. The high penetrance and temporal predictability of tumor induction raises issues related to the clonal structure of these lymphomas. Similarly, the clonality of responding CD8 T cells that infiltrate the tumor sites is unknown. Using TCRβ repertoire analysis tools, we demonstrated that MDV driven CD4+ T cell tumors were dominated by one to three large clones within an oligoclonal framework of smaller clones of CD4+ T cells. Individual birds had multiple tumor sites, some the result of metastasis (i.e. shared dominant clones) and others derived from distinct clones of transformed cells. The smaller oligoclonal CD4+ cells may represent an anti-tumor response, although on one occasion a low frequency clone was transformed and expanded after culture. Metastatic tumor clones were detected in the blood early during infection and dominated the circulating T cell repertoire, leading to MDV associated immune suppression. We also demonstrated that the tumor-infiltrating CD8+ T cell response was dominated by large oligoclonal expansions containing both “public” and “private” CDR3 sequences. The frequency of CD8+ T cell CDR3 sequences suggests initial stimulation during the early phases of infection. Collectively, our results indicate that MDV driven tumors are dominated by a highly restricted number of CD4+ clones. Moreover, the responding CD8+ T cell infiltrate is oligoclonal indicating recognition of a limited number of MDV antigens. These studies improve our understanding of the biology of MDV, an important poultry pathogen and a natural infection model of virus-induced tumor formation

Basic mechanism of leukocyte migration

Inflammation represents the consequence of capillary dilation with accumulation of fluid (edema) and the immigration of leukocytes. By the end of the last century, Metchnikoff noted the power of certain blood cells to move toward bacteria and foreign substances and ingest them. In fact, leukocytes adhere to the vascular endothelium, and subsequently leave the circulation by transendothelial migration driven by chemoattractants, a process known as diapedesis. Reversible adherence of leukocytes to endothelium, basement membranes, and other surfaces on which they crawl is an essential event in the establishment of inflammation, whose molecular basis is beginning to be understood. Inflammation can become chronic. The acute process, characterized by neutrophil infiltration and edema, gives way to a subsequent predominance of mononuclear phagocytes or lymphocytes. Insulin-dependent diabetes mellitus is the result of organ-specific autoimmune destruction of the insulin secreting beta-cells in the pancreatic islets of Langerhans. It has become evident that diabetes mellitus is a multifactorial disease caused in part by infiltrating T-lymphocytes, comparable to situations of inflammation. After presentation of the different effectors of the immune system and their fluxes through the body, this review will propose a general model of adhesion between leukocytes and endothelial cells. It will emphasize how the homing specificity of lymphocyte subsets to different lymphoid organs is ensured, and how leukocyte migration to sites of inflammation is regulated. Finally, general therapeutic perspectives based on adhesion molecules leading to cure or prevention of chronic inflammation will be discussed

The role of cell traffic in the emergence of the T lymphoid system

The role of the thymus is to ensure the differentiation and selection of T lymphocytes, which are one of the major players in the immune system. Recent studies show that the establishment of the T lymphoid system requires a complex cell traffic. In this field, avian embryos yield particularly informative developmental models because they are amenable to many experimental approaches during the phases of morphogenesis, and, in addition, the immune system resembles that of mammals