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Ribosome biogenesis is well described in Saccharomyces cerevisiae. In contrast only very little information is available on this pathway in plants. This study presents the characterization of five putative protein co-factors of ribosome biogenesis in Arabidopsis thaliana, namely Rrp5, Pwp2, Nob1, Enp1 and Noc4. The characterization of the proteins in respect to localization, enzymatic activity and association with pre-ribosomal complexes is shown. Additionally, analyses of T-DNA insertion mutants aimed to reveal an involvement of the plant co-factors in ribosome biogenesis. The investigated proteins localize mainly to the nucleolus or the nucleus, and atEnp1 and atNob1 co-migrate with 40S pre-ribosomal complexes. The analysis of T-DNA insertion lines revealed that all proteins are essential in Arabidopsis thaliana and mutant plants show alterations of rRNA intermediate abundance already in the heterozygous state. The most significant alteration was observed in the NOB1 T-DNA insertion line where the P-A3 fragment, a 23S-like rRNA precursor, accumulated. The transmission of the T-DNA through the male and female gametophyte was strongly inhibited indicating a high importance of ribosome co-factor genes in the haploid stages of plant development. Additionally impaired embryogenesis was observed in some mutant plant lines. All results support an involvement of the analyzed proteins in ribosome biogenesis but differences in rRNA processing, gametophyte and embryo development suggested an alternative regulation in plants.
[book review:] David Penney (Ed) 2013 Spider research in the 21st century – trends and perspectives
(2013)
The latest arachnological publication from Siri Scientific Press is a substantial compendium of spiderrelated topics covering many aspects of these fascinating animals’ biology. As the title suggests, the overarching theme running throughout this work are the advances which have been made in recent years – particularly through the application of novel methods and/or technologies – as well as productive directions for future research. Following an extensive foreword by Norman Platnick, which summarises the book’s main conclusions rather well, the volume itself is divided into nine self-contained and fully referenced chapters. All have been written by acknowledged experts in their fields and all provide an excellent account of the modern literature.
Auch wenn der Titel lediglich eine „non-annotated checklist“ verheißt, handelt es sich tatsächlich um mehr. Es ist die Neuauflage bzw. die Fortschreibung des Kataloges von Mikhailov (1997) sowie von dessen Ergänzungen (Mikhailov 1998, 1998, 2000). Die Checklist (der Katalogteil) umfasst alle Arten, die in den heutigen Ländern der ehemaligen Sowjetunion bis einschließlich 2011 nachgewiesen wurden.
This paper presents the first comprehensive list of 2,688 species of Staphylinidae (Coleoptera) recorded from Brazil. The list is based on the taxonomic and ecological literature, and new records from some insect collections, and includes locality references for each species. In addition, Brazilian localities and the country-level distribution outside of Brazil are provided for each species. Brazilian localities are organized by state, and include the bibliographic reference and page number where each locality was reported. All localities are geo-referenced, organized by state, and listed in an Appendix.
Translation is an important step in gene expression. The initiation of translation is phylogenetically diverse, since currently five different initiation mechanisms are known. For bacteria the three initiation factors IF1 – IF3 are described in contrast to archaea and eukaryotes, which contain a considerably higher number of initiation factor genes. As eukaryotes and archaea use a non-overlapping set of initiation mechanisms, orthologous proteins of both domains do not necessarily fulfill the same function. The genome of Haloferax volcanii contains 14 annotated genes that encode (subunits of) initiation factors. To gain a comprehensive overview of the importance of these genes, it was attempted to construct single gene deletion mutants of all genes. In 9 cases single deletion mutants were successfully constructed, showing that the respective genes are not essential. In contrast, the genes encoding initiation factors aIF1, aIF2γ, aIF5A, aIF5B, and aIF6 were found to be essential. Factors aIF1A and aIF2β are encoded by two orthologous genes in H. volcanii. Attempts to generate double mutants failed in both cases, indicating that also these factors are essential. A translatome analysis of one of the single aIF2β deletion mutants revealed that the translational efficiency of the second ortholog was enhanced tenfold and thus the two proteins can replace one another. The phenotypes of the single deletion mutants also revealed that the two aIF1As and aIF2βs have redundant but not identical functions. Remarkably, the gene encoding aIF2α, a subunit of aIF2 involved in initiator tRNA binding, could be deleted. However, the mutant had a severe growth defect under all tested conditions. Conditional depletion mutants were generated for the five essential genes. The phenotypes of deletion mutants and conditional depletion mutants were compared to that of the wild-type under various conditions, and growth characteristics are discussed.
A two week trip to Costa Rica was conducted between 26 May and 8 June 2013, sampling odonates in several provinces along the center to the pacific southern portionof the country. A total of 86 species in 34 genera were found, including 16 species of the genus Argia. Lists of all species by locality, photographs of live specimens, and illustrations and notes of described species of Argiaare presented to facilitate identification to other collectors.
Aging of biological systems is controlled by various processes which have a potential impact on gene expression. Here we report a genome-wide transcriptome analysis of the fungal aging model Podospora anserina. Total RNA of three individuals of defined age were pooled and analyzed by SuperSAGE (serial analysis of gene expression). A bioinformatics analysis identified different molecular pathways to be affected during aging. While the abundance of transcripts linked to ribosomes and to the proteasome quality control system were found to decrease during aging, those associated with autophagy increase, suggesting that autophagy may act as a compensatory quality control pathway. Transcript profiles associated with the energy metabolism including mitochondrial functions were identified to fluctuate during aging. Comparison of wild-type transcripts, which are continuously down-regulated during aging, with those down-regulated in the long-lived, copper-uptake mutant grisea, validated the relevance of age-related changes in cellular copper metabolism. Overall, we (i) present a unique age-related data set of a longitudinal study of the experimental aging model P. anserina which represents a reference resource for future investigations in a variety of organisms, (ii) suggest autophagy to be a key quality control pathway that becomes active once other pathways fail, and (iii) present testable predictions for subsequent experimental investigations.
The membrane proximal external region (MPER) of the HIV-1 glycoprotein gp41 is targeted by the broadly neutralizing antibodies 2F5 and 4E10. To date, no immunization regimen in animals or humans has produced HIV-1 neutralizing MPER-specific antibodies. We immunized llamas with gp41-MPER proteoliposomes and selected a MPER-specific single chain antibody (VHH), 2H10, whose epitope overlaps with that of mAb 2F5. Bi-2H10, a bivalent form of 2H10, which displayed an approximately 20-fold increased affinity compared to the monovalent 2H10, neutralized various sensitive and resistant HIV-1 strains, as well as SHIV strains in TZM-bl cells. X-ray and NMR analyses combined with mutagenesis and modeling revealed that 2H10 recognizes its gp41 epitope in a helical conformation. Notably, tryptophan 100 at the tip of the long CDR3 is not required for gp41 interaction but essential for neutralization. Thus bi-2H10 is an anti-MPER antibody generated by immunization that requires hydrophobic CDR3 determinants in addition to epitope recognition for neutralization similar to the mode of neutralization employed by mAbs 2F5 and 4E10.
Hot spots are characterized by the occurrence of „hot“ species, rare, endangered, phytogeographically (for example highly disjunct) or ecologically interesting species (for example heavy metal species). The Apuanian Alps (ital. Alpi Apuani) are a place of extraordinary botanical and also bryological interest. Although situated far from the west coast of Europe, many atlantic species are found there, which have isolated occurrences and show up next in Asturias, Macaronesia. Ireland or Scotland. Representative of the oceanic element in the bryoflora are Dumortiera hirsuta, Lejeunea lamacerina, Lophocolea fragrans, Plagiochila exigua, P. bifaria, Saccogyna viticulosa, Harpalejeunea ovata and Marchesinia mackaii, supplemented by ferns such as Trichomanes speciosum and Hymenophyllum tunbrigense (Cortini-Pedrotti et al. 1992). Reasons for the presence of such species in Italy are the extraordinary climatic conditions. Situated directly along the Meditrerranean Sea, the climate is mild and due to depressions in the gulf of Genova, the rain is caught by the mountains resulting in a high precipitation of about 1400 at the foot of the region and more than 3000 mm in the summit region. This does, however, not explain whether these species are relics from the Tertiary or dispersed from the W-coast of Europe after the Pleistocene glaciations.