Biogeographical and bioclimatic outline of Antarctica

Abstract

This study proposes a bioclimatic characterization and a new biogeographic division for the Antarctic territories up to the province level following the criteria and models of Rivas-Martínez et al. The Antarctic Kingdom comprises the continent of Antarctica, the surrounding ice-covered Antarctic islands, and the associated cold oceanic islands and archipelagos. It has two biogeographic regions: the Antarctic Region and the Subantarctic Insular Region. The Antarctic Region includes the entire pergelid Antarctic continent and the surrounding islands and archipelagos, and is characterized by upper suprapolar hyperoceanic and oceanic or Polar pergelid bioclimates on the coasts. The region has been divided into three pr6ovinces: Maritime Antarctica, West Antarctica and East Antarctica. The Subantarctic Insular Region comprises the circumantarctic islands and archipelagos that are widespread at the southern tip of the planet’s most important oceans, mostly in the subtemperate latitudinal zone inside or not far from the Antarctic Convergence. Bioclimatically, all insular subantarctic territories (excluding the South-American Tierra de Fuego, Terra Magellanica and large islands) are characterized by thermo-suprapolar and semipolar antarctic hyperoceanic bioclimates on the coasts. Four provinces – Falklandian-South Georgian, Kerguelenian, Macquarian and Aucklandian-Campbellian – have been recognized in this region. All these units are characterized by floristic bioindicators.     

The developmental regulator PatD modulates assembly of the cell-division protein FtsZ in the cyanobacterium Anabaena sp. PCC 7120

FtsZ is a tubulin-like GTPase that polymerizes to initiate the process of cell division in bacteria. Heterocysts are terminally differentiated cells of filamentous cyanobacteria that have lost the capacity for cell division and in which the ftsZ gene is downregulated. However, mechanisms of FtsZ regulation during heterocyst differentiation have been scarcely investigated. The patD gene is NtcA dependent and involved in the optimization of heterocyst frequency in Anabaena sp. PCC 7120. Here, we report that the inactivation of patD caused the formation of multiple FtsZ-rings in vegetative cells, cell enlargement, and the retention of peptidoglycan synthesis activity in heterocysts, whereas its ectopic expression resulted in aberrant FtsZ polymerization and cell division. PatD interacted with FtsZ, increased FtsZ precipitation in sedimentation assays, and promoted the formation of thick straight FtsZ bundles that differ from the toroidal aggregates formed by FtsZ alone. These results suggest that in the differentiating heterocysts, PatD interferes with the assembly of FtsZ. We propose that in Anabaena FtsZ is a bifunctional protein involved in both vegetative cell division and regulation of heterocyst differentiation. In the differentiating cells PatD-FtsZ interactions appear to set an FtsZ activity that is insufficient for cell division but optimal to foster differentiation.     

The effect of ionic liquid media on activity,selectivity and stability of Candida antarctica lipase B in transesterification reactions

Nineteen different 1,3-dialkylimidazolium-based ionic liquids (ILs) were used as reaction media for the synthesis of butyl butyrate by transesterification from vinyl butyrate and 1-butanol catalyzed by Candida antarctica lipase B (CaLB). The reaction was also carried out in hexane as a reference solvent. In all the water-immiscible ILs assayed, the enzymatic activity and selectivity were higher than that obtained in hexane. However, in water-miscible ILs, the activity was lower than in the reference solvent, although they showed >99.99% selectivity. Two solvent properties, hydrophobicity and nucleophilicity, were considered key parameters for analyzing the behavior of CaLB in ILs. In the case of ILs based on the same anion, the synthetic activity was gradually enhanced by increasing cation hydrophobicity. Furthermore, the activity of CaLB was greater in ILs containing anions of lower nucleophilicity. Stability studies indicate that CaLB exhibited greater stability in water-immiscible ILs than in water-miscible ILs.     

RIF1 Is Essential for 53BP1-Dependent Nonhomologous End Joining and Suppression of DNA Double-Strand Break Resection

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Highlights? RIF1 is essential for 53BP1-dependent CSR and fusion of dysfunctional telomeres ? BRCA1 antagonizes RIF1 in S phase to prevent error-prone repair by toxic NHEJ ? N-terminal phospho-SQ/TQ domain of 53BP1 interacts with and recruits RIF1 to DSBs ? RIF1 and 53BP1 promote NHEJ in G1 by blocking 5′ end resection of DSBs     

Stem cells: Insights into the secretome

Stem cells have been considered as possible therapeutic vehicles for different health related problems such as cardiovascular and neurodegenerative diseases and cancer. Secreted molecules are key mediators in cell–cell interactions and influence the cross talk with the surrounding tissues. There is strong evidence supporting that crucial cellular functions such as proliferation, differentiation, communication and migration are strictly regulated from the cell secretome. The investigation of stem cell secretome is accumulating continuously increasing interest given the potential use of these cells in regenerative medicine. The scope of the review is to report the main findings from the investigation of stem cell secretome by the use of contemporary proteomics methods and discuss the current status of research in the field. This article is part of a Special Issue entitled: An Updated Secretome.     

Mechanisms of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease affecting premature infants with long term effect on lung function into adulthood. Multiple factors are involved in the development of BPD. This review will summarize the different mechanisms leading to this disease and highlight recent bench and clinical research targeted at understanding the role of the mesenchyme (both its cellular and extracellular components) in the pathogenesis of BPD.     

Establishment of a conditional Nomo1 mouse model by CRISPR/Cas9 technology

Molecular Biology Reports - The Nomo1 gene mediates a wide range of biological processes of importance in embryonic development. Accordingly, constitutive perturbation of Nomo1 function may result...     

Yeast ribosomal protein L7 and its homologue Rlp7 are simultaneously present at distinct sites on pre-60S ribosomal particles

Ribosome biogenesis requires >300 assembly factors in Saccharomyces cerevisiae. Ribosome assembly factors Imp3, Mrt4, Rlp7 and Rlp24 have sequence similarity to ribosomal proteins S9, P0, L7 and L24, suggesting that these pre-ribosomal factors could be placeholders that prevent premature assembly of the corresponding ribosomal proteins to nascent ribosomes. However, we found L7 to be a highly specific component of Rlp7-associated complexes, revealing that the two proteins can bind simultaneously to pre-ribosomal particles. Cross-linking and cDNA analysis experiments showed that Rlp7 binds to the ITS2 region of 27S pre-rRNAs, at two sites, in helix III and in a region adjacent to the pre-rRNA processing sites C₁ and E. However, L7 binds to mature 25S and 5S rRNAs and cross-linked predominantly to helix ES7^Lb within 25S rRNA. Thus, despite their predicted structural similarity, our data show that Rlp7 and L7 clearly bind at different positions on the same pre-60S particles. Our results also suggest that Rlp7 facilitates the formation of the hairpin structure of ITS2 during 60S ribosomal subunit maturation.