Structure-function relationships in the growing hexa-coordinate hemoglobin sub-family

Hemoglobin and related heme proteins, generally referred to as 'globins', reversibly bind gaseous diatomic ligands (O2, NO, and CO) to a penta-coordinate heme iron atom, the ligand filling the sixth coordination site. Over the last decade, several new globins have been reported to display a functionally-relevant hexa-coordinate heme iron atom, whose sixth coordination site is taken by an endogenous protein ligand. The reversible intramolecular hexa- to penta-coordination process at the heme-Fe atom modulates exogenous ligand binding properties of hexa-coordinate globins. Here, we review current knowledge on hexa-coordinate globins in terms of their structural and functional properties.     

Concentrative uptake of cyclic ADP-ribose generated by BST-1+ stroma stimulates proliferation of human hematopoietic progenitors

Cyclic ADP-ribose (cADPR) is an intracellular calcium mobilizer generated from NAD(+) by the ADP-ribosyl cyclases CD38 and BST-1. cADPR, both exogenously added and paracrinally produced by a CD38(+) feeder layer, has recently been demonstrated to stimulate the in vitro proliferation of human hemopoietic progenitors (HP) and also the in vivo expansion of hemopoietic stem cells. The low density of BST-1 expression on bone marrow (BM) stromal cells and the low specific activity of the enzyme made it unclear whether cADPR generation by a BST-1(+) stroma could stimulate HP proliferation in the BM microenvironment. We developed and characterized two BST-1(+) stromal cell lines, expressing an ectocellular cyclase activity similar to that of BST-1(+) human mesenchymal stem cells, the precursors of BM stromal cells. Long term co-culture of cord blood-derived HP over these BST-1(+) feeders determined their expansion. Influx of paracrinally generated cADPR into clonogenic HP was mediated by a concentrative, nitrobenzylthioinosine- and dipyridamole-inhibitable nucleoside transporter, this providing a possible explanation to the effectiveness of the hormone-like concentrations of the cyclic nucleotide measured in the medium conditioned by BST-1(+) feeders. These results suggest that the BST-1-catalyzed generation of extracellular cADPR, followed by the concentrative uptake of the cyclic nucleotide by HP, may be physiologically relevant in normal hemopoiesis.     

A xylan-degrading strain of<Emphasis Type="Italic"> Sulfolobus solfataricus</Emphasis>: isolation and characterization of the xylanase activity

Two strains (O and X₂) of the hyperthermophilic crenarchaeon Sulfolobus solfataricus strain MT4 were selected and isolated for their ability to grow on xylan. O and X₂, grown on media containing oat spelt xylan and birchwood xylan as the sole nutrient source, respectively, produced the same thermostable xylanase that was demonstrated to be inducible in xylan cultures. In an oat spelt medium, S. solfataricus O underwent interesting morphological changes in the cell envelope, exhibiting mobile appendages not present in the typical coccal shape. The enzyme was prevalently membrane associated and showed a molecular mass of approximately 57.0 kDa. It was also highly thermostable, with a half-life of 47 min at 100°C, and exhibited an optimal temperature and pH of 90°C and 7.0, respectively. Xylo-oligosaccharides were the enzymatic products of xylan hydrolysis, and the smallest degradation product was xylobiose, thus indicating that the enzyme was an endoxylanase. The enzyme was able to bind weakly to crystalline cellulose (Avicel) and more strongly to insoluble xylan in a substrate amount-and temperature-dependent manner.Communicated by G. Antranikian     

Modulation of the immune response induced by gene electrotransfer of a hepatitis C virus DNA vaccine in nonhuman primates

Induction of multispecific, functional CD4+ and CD8+ T cells is the immunological hallmark of acute self-limiting hepatitis C virus (HCV) infection in humans. In the present study, we showed that gene electrotransfer (GET) of a novel candidate DNA vaccine encoding an optimized version of the nonstructural region of HCV (from NS3 to NS5B) induced substantially more potent, broad, and long-lasting CD4+ and CD8+ cellular immunity than naked DNA injection in mice and in rhesus macaques as measured by a combination of assays, including IFN-gamma ELISPOT, intracellular cytokine staining, and cytotoxic T cell assays. A protocol based on three injections of DNA with GET induced a substantially higher CD4+ T cell response than an adenovirus 6-based viral vector encoding the same Ag. To better evaluate the immunological potency and probability of success of this vaccine, we have immunized two chimpanzees and have compared vaccine-induced cell-mediated immunity to that measured in acute self-limiting infection in humans. GET of the candidate HCV vaccine led to vigorous, multispecific IFN-gamma+CD8+ and CD4+ T lymphocyte responses in chimpanzees, which were comparable to those measured in five individuals that cleared spontaneously HCV infection. These data support the hypothesis that T cell responses elicited by the present strategy could be beneficial in prophylactic vaccine approaches against HCV.     

Spatial-explicit assessment of current and future conservation options for the endangered Corsican Red Deer (Cervus elaphus corsicanus) in Sardinia

The Corsican red deer, a sub-species of the European red deer endemic to Sardinia and Corsica, was abundant on both islands at the beginning of 1900. It went extinct in Corsica and reached a minimum of 100 individuals in Sardinia by 1970. Numbers have recovered in Sardinia with more than 1,000 rutting males now present; in the 1980s the deer was reintroduced to Corsica, but the Sardinian population remains fragmented. We developed a potential distribution model in Sardinia using Ecological Niche Factor Analysis. To assess the deer’s protection status we compared the model with the existing and proposed conservation areas and investigated different conservation scenarios in relation to the expansion of its current range and resilience to future changes in land use and predicted trends of desertification. According to our results over 70% of Sardinia is unsuitable to the deer, nevertheless high suitability areas (Mediterranean forests away from main roads) are available throughout the island, particularly in the south and in the central-eastern part. Existing protected areas do not provide for the conservation of the deer but public owned forests, where hunting is prohibited, extend some level of protection, and the protected areas proposed by the Regional administration, if implemented, will be increasing this protection. Three main areas have emerged as conservation priorities to guarantee adequate conservation potential in the future. Our approach provides valuable data to inform conservation policy, and could be easily replicated in other parts of the Mediterranean.     

Revised nomenclature for the mammalian long-chain acyl-CoA synthetase gene family

By consensus, the acyl-CoA synthetase (ACS) community, with the advice of the human and mouse genome nomenclature committees, has revised the nomenclature for the mammalian long-chain acyl-CoA synthetases. ACS is the family root name, and the human and mouse genes for the long-chain ACSs are termed ACSL1,3-6 and Acsl1,3-6, respectively. Splice variants of ACSL3, -4, -5, and -6 are cataloged. Suggestions for naming other family members and for the nonmammalian acyl-CoA synthetases are made.     

[3H]Ketanserin Binding in Human Brain Postmortem

This study aimed at comparing the binding characteristics of [³H]ketanserin, a high-affinity serotonin 2A (5-HT_2A) receptor antagonist, in the prefrontal cortex, hippocampus and striatum of human brain post-mortem. The results indicated the presence of a single population of binding sites in all the regions investigated, with no statistical difference in maximum binding capacity (B_max) or dissociation constant (K_d) values. The pharmacological profile of [³H]ketanserin binding was consistent with the labeling of the 5-HT_2A receptor, since it revealed a competing drug potency ranking of ketanserin = spiperone > clozapine = haloperidol > methysergide > mesulergine > 5-HT. In conclusion, the 5-HT_2A receptor, as labeled by [³H]ketanserin, would seem to consist of a homogenous population of binding sites and to be equally distributed in human prefronto-cortical, limbic and extrapyramidal structures.