Characterization and purification of lupus antigen La, and RNA-binding protein.

HeLa cell La antigen, an RNA-binding protein, was characterized by using two-dimensional gel electrophoresis. Eight isoelectric forms (pI 6 to 7) were observed, many containing phosphate. An in vitro translation product similar in size and antigenicity was identified. The HeLa cell protein purified by using an assay based on ribonucleoprotein reconstitution with adenovirus VA RNAI also comprised several isoelectric forms.     

Prefrontal Neurons Encode Actions and Outcomes in Conjunction with Spatial Location in Rats Performing a Dynamic Delayed Non-Match to Position Task

To respond adaptively to change organisms must utilize information about recent events and environmental context to select actions that are likely to produce favorable outcomes. We developed a dynamic delayed nonmatching to position task to study the influence of spatial context on event-related activity of medial prefrontal cortex neurons during reinforcement-guided decision-making. We found neurons with responses related to preparation, movement, lever press responses, reinforcement, and memory delays. Combined event-related and video tracking analyses revealed variability in spatial tuning of neurons with similar event-related activity. While all correlated neurons exhibited spatial tuning broadly consistent with relevant task events, for instance reinforcement-related activity concentrated in locations where reinforcement was delivered, some had elevated activity in more specific locations, for instance reinforcement-related activity in one of several locations where reinforcement was delivered. Timing analyses revealed a limited set of distinct response types with activity time-locked to critical behavioral events that represent the temporal organization of dDNMTP trials. Our results suggest that reinforcement-guided decision-making emerges from discrete populations of medial prefrontal neurons that encode information related to planned or ongoing movements and actions and anticipated or actual action-outcomes in conjunction with information about spatial context.     

Secondary structural analysis of two recombinant murine proteins, interleukins 1 alpha and 1 beta: is infrared spectroscopy sufficient to assign structure?

The secondary structure for two murine recombinant proteins, interleukins 1 alpha and 1 beta (rmIL-1 alpha and -1 beta), has been analyzed by Fourier transform infrared (IR) spectroscopy and then compared to results obtained by X-ray diffraction, circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopy. The IR results obtained here for rmIL-1 alpha and -1 beta suggested that their secondary structures consisted predominantly of beta-sheets or strands. However, the analysis also revealed a significant absorption band near 1656 cm-1, which is typically assigned to alpha-helical or random structures. When these same murine polypeptides were analyzed by CD, no evidence of alpha-helical structures was observed. Further, published X-ray diffraction and NMR studies characterizing the human forms of IL-1 alpha and -1 beta indicate the absence of alpha-helices and that the human proteins are composed mainly of beta-strands (i.e., greater than 55%), with approximately 24% of the amino acids involved in large loops connecting the strands. The murine IL-1 proteins, when compared to their respective human counterparts, each show greater than 80% sequence homology. Given this fact, the CD analyses, and the result that this IR band amounted to 21% of the overall integrated area, the absorption peak at 1656 cm-1 was attributed to the presence of large loops rather than to alpha-helical or random structures. Such a structural assignment appears reasonable and is totally consistent with the established existence of large loops in the human forms as well as in other proteins found to fold similarly (viz., human bFGF).(ABSTRACT TRUNCATED AT 250 WORDS)     

Relations entre la fourmi parasiteFormicoxenus provancheri et son hôteMyrmica incompleta. Données biologiques et éthologiques (Hym. Formicidae)

Résumé La biologie et le comportement deFormicoxenus provancheri, fourmi parasite de Myrmica incompleta, sont précisées. Cette espèce forme de grandes sociétés polycaliques où chaque unité conserve une certaine autonomie (mise en évidence par le faible taux de passage d'une unité à l'autre et la discrimination du couvain de chaque unité). L'adoption desFormicoxenus par lesMyrmica est facile et n'entraîne qu'une mortalité très faible parmi les parasites, même lorsqu'il s'agit deMyrmica totalement indemnes de parasites. Nous décrivons deux comportements importants dans les interactions entre les deux espèces: le léchage de l'hôte et le comportement d'apaisement envers l'hôte. Les larves deFormicoxenus sont consommées par l'hôteMyrmica, ce qui explique la nécessité pour lesFormicoxenus de garder leur couvain à l'écart de l'hôte. Il est probable que la formation des supercolonies s'effectue par bouturage d'une gyne (ou d'une ergate fécondée) accompagnée d'ergates, qui va fonder une nouvelle calie à la périphérie de la société hôte. Le problème de la dissémination du parasite est posé: les gynes après fécondation sont fortement agressées si on tente de les introduire dans une société étrangère.

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Biological and ethological observations on the interactions between the parasite ant Formicoxenus provancheri and its host Myrmica incompleta (Hym. Formicidae)

Summary Information on the biology and the behaviour ofFormicoxenus provancheri, a parasite ofMyrmica incompleta, is presented.F. provancheri forms large polycalic societies whith each unit maintaining some independance: movements from one unit to another are not frequent and there is brood discrimination between different units. Adoption ofFormicoxenus ergates byMyrmica societies is easy, the mortality is very low among the parasites, even if the adoptiveMyrmica were previously completely parasite free. The larvae ofFormicoxenus can be eaten by the host Myrmica', this explains the necessity for theFormicoxenus to keep their brood apart from the host. Grooming of the host is very frequent. This might enable the parasite to acquire the species-specific odour of the host colony. Grooming might also be a way of obtaining some nutricious substances from the host body. Appeasement behaviour presented by theFormicoxenus is described. New small units of colonies, at the periphery of the host society, are probably founded by budding of any fecundated female leaving the nest with some ergates. This leads to the formation of super-societies by the parasite. The probleme of how the parasite spreads is not answered by this study because it was shown that newly fecundated gynes suffer strong aggression when they enter an alien host society.

     

Upregulation of cellular triacylglycerol - free fatty acid cycling by oleate is associated with long-term serum-free survival of human breast cancer cells.

We previously showed that exogenous oleate protects human breast cancer cells against palmitate-induced apoptosis in part by increasing esterification of this free fatty acid (FFA) into triacylglycerol (TG). Here, we studied the mechanism whereby oleate protects these cells against apoptosis induced by serum withdrawal. The metabolism of FFA, TG, and glucose, in parallel with long-term cell survival in the absence of serum, was investigated in a panel of human breast cancer cell lines and in nontransformed MCF-10A cells after treatment with exogenous oleate. Short-term (3-24 h) exposure of MDA-MB-231 human breast cancer cells to exogenous oleate resulted in a dose-dependent long-term (10 day) serum-free survival that correlated with the accumulation of TG in lipid droplets and with upregulation of lipolysis. Both effects persisted for several days after oleate removal. Rapid TG lipolysis and FFA re-esterification, supported by high rates of glycolysis that provide the glycerol backbone for TG synthesis, are consistent with the presence of very active TG-FFA cycling in human breast cancer cells. Only the cancer cell lines capable of accumulating TG showed long-term serum-free survival after oleate treatment. The results suggest that upregulation of TG-FFA cycling induced by oleate may be involved in maintenance of human breast cancer cell survival.     

Identification of ribosomal protein autoantigens

Approximately 20% of patients with systemic lupus erythematosus and with anti-Sm autoantibodies synthesize autoantibodies, called anti-rRNP, to components of the ribosome. We found that anti-rRNP sera reacted predominantly with three ribosomal phosphoproteins of approximate Mr = 38,000, 16,000 and 15,000, both by immunoprecipitation and by immunoblotting. The human autoantibodies cross-reacted with similar antigens present in rodent, brine shrimp, and yeast cells but reacted weakly if at all with proteins of bacteria. Thus the human autoantibodies recognize epitopes that are widely conserved in evolution. Purified ribosomal proteins together with specific rabbit antisera were used to identify the two smaller rRNP antigens as the acidic phosphoproteins of the large ribosomal subunit, designated P1/P2(L40/L41) (rat), eL7/eL12 (Artemia, brine shrimp), and A1/A2 (yeast). These proteins function in the elongation step of protein synthesis in an analogous fashion to the L7/L12 ribosomal proteins of E. coli. The 38,000-dalton rRNP antigen corresponds to a nonacidic protein also associated with the large ribosomal subunit. The human autoantibodies appear to have a specificity similar to that of a previously described mouse monoclonal antibody obtained from mice injected with heterologous (chick) ribosomes, suggesting that both the human polyclonal autoantibodies and the mouse monoclonal recognize a class of epitope(s) that is common in all three ribosomal proteins. In addition, we found that many of the anti-ribosomal sera contained a further class of autoantibodies reactive with naked RNA. These may be similar to the anti-RNA antibodies previously described in both humans and mice with autoimmune disease.     

Estimation of C3 levels in cerebrospinal fluid by electroimmunodiffusion

C3 levels have been determined by the electroimmunodiffusion technique in the CSF of patients with a wide variety of pathologies. The patients were grouped on the basis of protein content and G/A ratio of the CSF as I) patients with normal meningeal permeability and apparent absence of local gamma-globulin synthesis; II) patients with increased meningeal permeability; III) patients with characteristics of MS, i.e. increase of IgG accompanied by a normal or slightly elevated protein content, Group III showed a lower level of C3 when expressed at % of the total protein and also as % of the total protein less gamma-globulins of the CSF. Other parameters of the CSF are also recorded. It was shown that only the expression of C3 concentration relative to the total protein content of the CSF produced meaningful analytical data.