Biological control ofCuscuta spp. II. Biology and host-plant range ofMelanagromyza cuscutae Hering [Dipt. agromyzidae]

Résumé Melanagromyza cuscutae Hering était considéré comme un agent biotique prometteur pour la lutte biologique contre la Cuscute. Dans les conditions de laboratoire, les imagos en présence de Cuscute et d'une solution de miel s'accouplent 1 à 4 jours après leur émergence, habituellement le matin, pendant 2 à 5 heures. Les femelles pondent 2 à 8 jours plus tard et cela durant 6 à 15 jours; au cours de leur vie (8 à 21 jours), chaque femelle dépose 11 à 132 œufs avec un maximum de 31 œufs dans une journée. L'éclosion des œufs se produit après 1 ou 2 jours. Les 3 stades larvaires et le stade pupe durent respectivement 7 à 8 et 8 à 13 jours. La ponte détermine une hyperplasie des cellules de la plante h?te et le forage des tiges entra?ne leur durcissement, leur noircissement puis leur dessiccation sur 10 cm. Un fort parasitisme (60–70%) par 6 espèces d'Hyménoptères a été observé en mai et juin. La Mouche était active en mars-avril et septembre–novembre en plaine et en juin–juillet en montagne, lorsque les températures étaient comprises entre 17 et 23°C. Les périodes défavorables sont passées à l'état de pupe dans les tiges minées. Les tests de spécificité ont montré que les femelles fécondées refusent de pondre dans 81 espèces de plantes appartenant à 42 familles. Seuls,Tradescantia sp. etIpomoea batatas re?urent chacune 1 œuf qui évolua normalement tandis que la larve n'a pas poursuivi son développement. L'alimentation de l'adulte surCuscuta semble essentielle pour la reproduction: en l'absence de cette plante, l'accouplement et le développement ovarien n'ont pas lieu.      

Soil sampling and isolation of extracellular DNA from large amount of starting material suitable for metabarcoding studies

DNA metabarcoding refers to the DNA-based identification of multiple species from a single complex and degraded environmental sample. We developed new sampling and extraction protocols suitable for DNA metabarcoding analyses targeting soil extracellular DNA. The proposed sampling protocol has been designed to reduce, as much as possible, the influence of local heterogeneity by processing a large amount of soil resulting from the mixing of many different cores. The DNA extraction is based on the use of saturated phosphate buffer. The sampling and extraction protocols were validated first by analysing plant DNA from a set of 12 plots corresponding to four plant communities in alpine meadows, and, second, by conducting pilot experiments on fungi and earthworms. The results of the validation experiments clearly demonstrated that sound biological information can be retrieved when following these sampling and extraction procedures. Such a protocol can be implemented at any time of the year without any preliminary knowledge of specific types of organisms during the sampling. It offers the opportunity to analyse all groups of organisms using a single sampling/extraction procedure and opens the possibility to fully standardize biodiversity surveys.     

Complete genome sequence of Marinobacter adhaerens type strain (HP15), a diatom-interacting marine microorganism

Marinobacter adhaerens HP15 is the type strain of a newly identified marine species, which is phylogenetically related to M. flavimaris, M. algicola, and M. aquaeolei. It is of special interest for research on marine aggregate formation because it showed specific attachment to diatom cells. In vitro it led to exopolymer formation and aggregation of these algal cells to form marine snow particles. M. adhaerens HP15 is a free-living, motile, rod-shaped, Gram-negative gammaproteobacterium, which was originally isolated from marine particles sampled in the German Wadden Sea. M. adhaerens HP15 grows heterotrophically on various media, is easy to access genetically, and serves as a model organism to investigate the cellular and molecular interactions with the diatom Thalassiosira weissflogii. Here we describe the complete and annotated genome sequence of M. adhaerens HP15 as well as some details on flagella-associated genes. M. adhaerens HP15 possesses three replicons; the chromosome comprises 4,422,725 bp and codes for 4,180 protein-coding genes, 51 tRNAs and three rRNA operons, while the two circular plasmids are ~187 kb and ~42 kb in size and contain 178 and 52 protein-coding genes, respectively.     

Recent trends using natural polymeric nanofibers as supports for enzyme immobilization and catalysis

All the disciplines of science, especially biotechnology, have given continuous attention to the area of enzyme immobilization. However, the structural support made by material science intervention determines the performance of immobilized enzymes. Studies have proven that nanostructured supports can maintain better catalytic performance and improve immobilization efficiency. The recent trends in the application of nanofibers using natural polymers for enzyme immobilization have been addressed in this review article. A comprehensive survey about the immobilization strategies and their characteristics are highlighted. The natural polymers, e.g., chitin, chitosan, silk fibroin, gelatin, cellulose, and their blends with other synthetic polymers capable of immobilizing enzymes in their 1D nanofibrous form, are discussed. The multiple applications of enzymes immobilized on nanofibers in biocatalysis, biosensors, biofuels, antifouling, regenerative medicine, biomolecule degradation, etc.; some of these are discussed in this review article.     

Blocking intrahepatic deletion of activated CD8+ T cells by an altered peptide ligand

BACKGROUND: Activated CD8(+) T cells are retained by the healthy liver where the majority undergo apoptosis. The intrahepatic apoptosis of activated CD8(+) T cells is enhanced by the presence of SIINFEKL peptide. It is of great interest to identify strategies for maintaining intrahepatic T cell number and function in the presence of SIINFEKL peptides. AIM: Our aim was to test if low affinity peptides can block SIINFEKL peptide induced T cell deletion. METHODS: We used an in vivo model of intrahepatic CD8(+) T cell deletion with peptides of different affinities. RESULTS AND DISCUSSION: We show that the intrahepatic deletion of CD8(+) T cells by SIINFEKL peptide results in loss of in vivo cytotoxic T lymphocyte function. In contrast we show that a low affinity peptide (G4) does not result in intrahepatic deletion of CD8(+) T cells. High concentrations G4 peptide can however block intrahepatic deletion of activated CD8(+) T cells, and prevent loss of in vivo cytotoxicity due to SIINFEKL peptide. This is the first demonstration of blocking of SIINFEKL peptide induced CD8(+) T cell deletion in the liver, with enhancement of in vivo cytotoxicity.     

Ethics and scientific publication

This article summarizes the major categories of ethical violations encountered during submission, review, and publication of scientific articles. We discuss data fabrication and falsification, plagiarism, redundant and duplicate publication, conflict of interest, authorship, animal and human welfare, and reviewer responsibility. In each section, pertinent historical background and citation of relevant regulations and statutes are provided. Furthermore, a specific case(s) derived from actual situations is(are) presented. These cases were chosen to highlight the complexities that investigators and journals must face when dealing with ethical issues. A series of discussion questions follow each case. It is our hope that by increasing education and awareness of ethical matters relevant to scientific investigation and publication, deviations from appropriate conduct will be reduced.     

Induction of Murine Intestinal Inflammation by Adoptive Transfer of Effector CD4+CD45RBhigh T Cells into Immunodeficient Mice

There are many different animal models available for studying the pathogenesis of human inflammatory bowel diseases (IBD), each with its own advantages and disadvantages. We describe here an experimental colitis model that is initiated by adoptive transfer of syngeneic splenic CD4⁺CD45RB^high T cells into T and B cell deficient recipient mice. The CD4⁺CD45RB^high T cell population that largely consists of naïve effector cells is capable of inducing chronic intestinal inflammation, closely resembling key aspects of human IBD. This method can be manipulated to study aspects of disease onset and progression. Additionally it can be used to study the function of innate, adaptive, and regulatory immune cell populations, and the role of environmental exposures, i.e., the microbiota, in intestinal inflammation. In this article we illustrate the methodology for inducing colitis with a step-by-step protocol. This includes a video demonstration of key technical aspects required to successfully develop this murine model of experimental colitis for research purposes.