The Ag85B protein of Mycobacterium tuberculosis may turn a protective immune response induced by Ag85B-DNA vaccine into a potent but non-protective Th1 immune response in mice

Clarifying how an initial protective immune response to tuberculosis may later loose its efficacy is essential to understand tuberculosis pathology and to develop novel vaccines. In mice, a primary vaccination with Ag85B-encoding plasmid DNA (DNA-85B) was protective against Mycobacterium tuberculosis (MTB) infection and associated with Ag85B-specific CD4+ T cells producing IFN-gamma and controlling intramacrophagic MTB growth. Surprisingly, this protection was eliminated by Ag85B protein boosting. Loss of protection was associated with a overwhelming CD4+ T cell proliferation and IFN-gamma production in response to Ag85B protein, despite restraint of Th1 response by CD8+ T cell-dependent mechanisms and activation of CD4+ T cell-dependent IL-10 secretion. Importantly, these Ag85B-responding CD4+ T cells lost the ability to produce IFN-gamma and control MTB intramacrophagic growth in coculture with MTB-infected macrophages, suggesting that the protein-dependent expansion of non-protective CD4+ T cells determined dilution or loss of the protective Ag85B-specific CD4+ induced by DNA-85B vaccination. These data emphasize the need of exerting some caution in adopting aggressive DNA-priming, protein-booster schedules for MTB vaccines. They also suggest that Ag85B protein secreted during MTB infection could be involved in the instability of protective anti-tuberculosis immune response, and actually concur to disease progression.     

Transport of Phosphatidylserine from Microsomes to the Inner Mitochondrial Membrane in Brain Tissue

Abstract: Phosphatidylserine was labeled by incubating rat brain homogenates with [3-¹⁴C]serine in the presence of Ca²⁺ (base-exchange conditions). Some labeled phosphati-dylethanolamine also forms, in spite of the inhibition of Ca²⁺ on phosphatidylserine decarboxylase. Phosphatidylserine labeling and decarboxylation also occur on incubating a mixture of purified mitochondria and microsomes, suggesting that no soluble factors are necessary for the synthesis and the decarboxylation of phosphatidylserine. Ca²⁺ favors the transfer of phosphatidylserine from microsomes (where it forms) to mitochondria (where it is decarboxylated). The specific radioactivity of the phosphatidylserine transferred to mitochondria is higher than that of microsomal phosphatidylserine. This finding supports the hypothesis that the lipid is compartmentalized in microsomes and that radioactive, newly synthesized phosphatidylserine is much better exported than the bulk of microsomal phospholipid.     

VGLUT1 and VGAT are sorted to the same population of synaptic vesicles in subsets of cortical axon terminals

Glutamate and GABA mediate most of the excitatory and inhibitory synaptic transmission; they are taken up and accumulated in synaptic vesicles by specific vesicular transporters named VGLUT1-3 and VGAT, respectively. Recent studies show that VGLUT2 and VGLUT3 are co-expressed with VGAT. Because of the relevance this information has for our understanding of synaptic physiology and plasticity, we investigated whether VGLUT1 and VGAT are co-expressed in rat cortical neurons. In cortical cultures and layer V cortical terminals we observed a population of terminals expressing VGLUT1 and VGAT. Post-embedding immunogold studies showed that VGLUT1+/VGAT+ terminals formed both symmetric and asymmetric synapses. Triple-labeling studies revealed GABAergic synapses expressing VGLUT1 and glutamatergic synapses expressing VGAT. Immunoisolation studies showed that anti-VGAT immunoisolated vesicles contained VGLUT1 and anti-VGLUT1 immunoisolated vesicles contained VGAT. Finally, vesicles containing VGAT resident in glutamatergic terminals undergo active recycling. In conclusion, we demonstrate that in neocortex VGLUT1 and VGAT are co-expressed in a subset of axon terminals forming both symmetric and asymmetric synapses, that VGLUT1 and VGAT are sorted to the same vesicles and that vesicles at synapses expressing the vesicular heterotransporter participate in the exo-endocytotic cycle.     

Both Recent and Pleistocene geography determine animal distributional patterns in the Tuscan Archipelago

Cluster analyses, Parsimony Analysis of Endemicity, species–area relationships, Mantel tests, partial Mantel tests and levels of endemism were used to investigate the influence of current geography and paleogeography on the composition of the fauna of the Tuscan Islands, a small archipelago in the Mediterranean. The composition of terrestrial mollusc and tenebrionid beetle faunas was prevalently influenced by Pleistocene conditions. The composition of butterfly (and possibly reptile) island fauna was influenced by both present (Holocene) and Pleistocene factors. Finally, chrysids were influenced only by present factors. On the whole, both present and historical factors concurred to determine present distributional patterns, but their relative influence varied according to the mobility of the group considered. Results provided here give some insights into the treatment of endemics to elucidate historical relationships among areas and add further momentum to a general model of biotic dynamics in landbridge archipelagos.     

Influence of island geography,age and landscape on species composition in different animal groups

Aim To study the importance of ecological and geographical factors in explaining arthropod species composition on islands. Location The Aeolian Islands, a volcanic archipelago in the central Mediterranean, near Sicily. Methods The influence of island area, age, distance to the mainland, distance to the nearest island and land cover categories on species composition of arthropod groups was analysed using canonical correspondence analysis (CCA). The use of multiple animal groups in the same archipelago allowed the development of two complementary approaches based on CCA – a ‘taxon‐focused’ approach and an ‘island‐focused’ approach – to elucidate, respectively, how different taxa respond to the same environmental factors, and which factors are mainly responsible for the composition of the faunas in different locations. Results Island area was an important factor in explaining species composition in Chilopoda, Orthoptera and Tenebrionidae. Distance to the mainland was important mainly for Carabidae. Distance to the closest island was important for many groups. By contrast, island age exerted a significant influence only on the species composition of Orthoptera. Various groups were influenced by a combination of broad‐leaved forest and natural grassland. Main conclusions The example of the arthropods of the Aeolian Islands indicates that the influence of a given island characteristic on species composition varies among groups, although measures of inter‐island isolation were typically more important for taxa than isolation from the mainland source. This suggests that colonization of islands may occur mostly by stepping‐stone dispersal.     

Release of Endogenous Amino Acids from Superior Colliculus of the Rabbit: In Vitro Studies After Retinal Ablation

Tissue slices from the superior colliculi (SC) of the rabbit were superfused and investigated 1 week after unilateral eye removal. Amino acid levels were determined both in the tissue slices and in the medium after chemical depolarisation (56 mM K). The amino acid determinations were done fluorimetrically by precolumn derivation and HPLC separation. Colliculi contralateral to the enucleation exhibited a 16% reduction in glutamate compared with the ipsilateral colliculi. The Ca-dependent release of glutamate or other amino acids tested was not appreciably affected by enucleation. However, both the total and the Ca-independent release of glutamate was lower from contralateral SC slices compared with the ipsilateral slices. The results do not favour glutamate as the major optic nerve transmitter in the rabbit, but do not rule out glutamate as a transmitter in a minor population of retinal fibres.     

Supramolecular organization of lysophosphatidylcholine-packaged gramicidin A′

Heat derived gramicidin A′/l-α-lysophosphatidylcholine complexes were separated on a sucrose gradient to form two fractions: Fraction A which had an approximately constant Gramicidin A′ to phospholipid ratio of 8 to 10 lipid molecules per Gramicidin A′ molecule and Fraction B which had a larger but variable ratio. Fluorescence and circular dichroism studies confirmed Fraction A to be a lipid-incorporated channel state. Electron microscopic studies, using uranyl acetate negative staining, showed fraction A to be a membranous state with the formation of bilayer vesicles, that is, the interaction of peptide and phospholipid micelles causes the lipid to reorganize into a bilayer structure. Freeze-fracture replicas of the channel incorporated state demonstrated the presence of a supramolecular organization of particles exhibiting a tendency to form rows with a 50–60 Å periodicity along the row and with 70–80 Å distance between rows. An idealized working model for the incorporated state is presented.