Intrinsic and extrinsic innervation of the amphibians esophagic myenteric plexuses

The innervation of Rana ridibunda esophagus myenteric plexuses has been studied by the following methods: demonstration of cholinesterase activity; FIF method for catecholamines; immunohistochemistry for VIP, SP and SOM, and conventional electron microscopy. The cholinergic innervation is important in the esophagus wall where, in addition to the well known extrinsic component, there is a rich intrinsic plexus with cells and fibres widely distributed. The esophagus, together with the intestine, are the Rana gut portions where the adrenergic component is more broadly expressed. The adrenergic innervation seems to be almost entirely of extrinsic origin. We have shown that, for the tested peptides, there is an intrinsic innervation represented by VIP, SP and SOM like plexuses. We do not discard nonetheless an extrinsic component. The ultrastructure reveals the morphological characteristics of the enteric neurons as well as the fine inter-relationships between the nervous elements and the functional components of the esophagic wall.     

The multiple-minima problem in small peptides revisited. The Threshold Accepting approach.

A recently reported optimization method, known as Threshold Accepting, was tested for the purpose of locating the structure of several peptide molecules with the lowest conformational energy. A comparison with previous results obtained with the Simulated Annealing technique was made. Our study indicate Threshold Accepting as a better technique in locating such structures.     

Cyclic AMP and adenylate cyclase activators stimulate Trypanosoma cruzi differentiation

A chemically defined in vitro differentiating condition was used to study the potential role of cyclic AMP (cAMP) and adenylate cyclase activators on the transformation of Trypanosoma cruzi epimastigotes to the infective metacyclic trypomastigotes (metacyclogenesis). It was observed that both addition of cAMP analogs or adenylate cyclase activators to the differentiating medium stimulated the transformation of epimastigotes to metacyclic trypomastigotes. These results were further corroborated by showing that inhibitors of cAMP phosphodiesterase were stimulatory while activators of this enzyme inhibited the metacyclogenesis process. On the other hand, inhibitors of calmodulin inhibited the transformation of epimastigotes to metacyclic trypomastigotes, suggesting that T. cruzi adenylate cyclase might be activated by calmodulin. In addition, the results strongly suggest that guanine nucleotide binding proteins are involved in T. cruzi adenylate cyclase activation. This system may be useful for studying cell differentiation mechanisms in eukaryotes.     

Comparative studies of selective media for recovery of Staphylococcus aureus from natural waters

Several selective media currently used for the enumeration of Staphylococcus aureus from different sources were evaluated in order to establish their quantitative recovery, specificity and degree of selectivity, using different types of water samples. The highest selectivity and reliability in the enumeration of Staph. aureus from the samples was obtained on Borrego-Florido-Romero-0 (BFR-0) and KRANEP agars. The method that produced the highest recovery of Staph. aureus was BFR-0 agar with membrane filter and incubation at 36 degrees C for 48-72 h.     

Effect of Naturally Occurring nif Reiterations on Symbiotic Effectiveness in Rhizobium phaseoli

Most naturally occurring strains of Rhizobium phaseoli possess reiteration of the nif genes. Three regions contain nitrogenase structural genes in strain CFN42. Two of these regions (a and b) have copies of nifH, nifD, and nifK, whereas the third region (c) contains only nifH. Strains containing mutations in either nif region a or nif region b had significantly diminished symbiotic effectiveness compared with the wild-type strain on the basis of nodule mass, total nitrogenase activity per plant, nitrogenase specific activity, total nitrogen in the shoot, and percentage of nitrogen. A strain containing mutations in both nif region a and nif region b was totally ineffective. These data indicate that both nif region a and nif region b are needed for full symbiotic effectiveness in R. phaseoli.     

Comparative study of different methods for detection and enumeration of Salmonella spp. in natural waters

Seven enrichment media (two proposed by the authors) for detecting salmonellas from polluted freshwater were compared. The Most Probable Number technique for enumeration of salmonellas in water samples was used, directly adding filtered water to buffered peptone water as the pre-enrichment medium. The results indicate that Rappaport-Vassiliadis/43 and Rappaport-Vassiliadis/43 supplemented with 10 micrograms of sodium novobiocin per ml are the best media for the recovery and enumeration of salmonellas from water samples.     

Transfer of nonglucosylated oligosaccharide from lipid to protein in a mammalian cell

We have previously shown that the glucosidase inhibitor, N-methyl-1-deoxynojirimycin (MedJN), only partially inhibited N-linked complex oligosaccharide biosynthesis in F9 teratocarcinoma cells whereas the alpha-mannosidase I inhibitor, manno-1-deoxynojirimycin, completely prevented this synthesis (Romero, P. A. and Herscovics, A. (1986) Carbohydr. Res. 151, 21-28). In order to determine whether a pathway independent of processing glucosidases can occur, F9 cells were pulse-labeled for 2 min with D-[2-3H]mannose in the presence or absence of 2 mM MedJN. In control cells, Man7GlcNAc was identified in the protein-bound oligosaccharides released with endo-beta-N-acetylglucosaminidase H, in addition to the expected Glc1-3Man9GlcNAc and Man9GlcNAc arising from processing of Glc3Man9GlcNAc. MedJN completely prevented the removal of glucose residues from Glc3Man9GlcNAc, but did not greatly affect the appearance of Man7GlcNAc associated with protein. Labeled Man7GlcNAc was also found in the lipid-linked oligosaccharides of both control and treated cells. The 2-min pulse-labeled Man7GlcNAc obtained from both the lipid and protein fractions were shown to have identical structures by concanavalin A-Sepharose chromatography and by acetolysis and were clearly different from the Man7GlcNAc obtained from the usual processing pathway. These results demonstrate that transfer of a nonglucosylated oligosaccharide (Man7GlcNAc2) from dolichyl pyrophosphate to protein occurs in F9 cells.     

Comparative study of different methods for detection and enumeration of Salmonella spp. in natural waters

Seven enrichment media (two proposed by the authors) for detecting salmonellas from polluted freshwater were compared. The Most Probable Number technique for enumeration of salmonellas in water samples was used, directly adding filtered water to buffered peptone water as the pre-enrichment medium. The results indicate that Rappaport-Vassiliadis/43 and Rappaport-Vassiliadis/43 supplemented with 10 μg of sodium novobiocin per ml are the best media for the recovery and enumeration of salmonellas from water samples.     

Secretory IgA and secretory component in women affected by recidivant vaginal candidiasis

Local immunity was evaluated in 47 patients affected by recidivant vaginal candidiasis and 33 control women. IgG, IgA, IgM and secretory component (SC) were determined by single radial immunodiffusion in samples of cervicovaginal secretion. IgG in dosable levels was detected in 17/47 samples (36.2%) and IgA in 15/47 patients (31.9%) whereas in the controls, the incidence was 31/33 (93.9%) for IgG and 24/33 (72.7%) for IgA. The difference was significative (P< 0.001) for both immunoglobulins. Significant differences were not obtained for IgM. The SC was detected in 4/47 cervicovaginal secretions of patients affected by candidiasis (8.5%) whereas in the control samples the incidence was 21/33 (63.6%) (P<0.001). In only 2/15 patients with dosable levels of IgA (13%) the secretory nature of this immunoglobulin could be shown by its reaction with anti-SC serum. In the control group, secretory IgA was detected in 19/24 cases (79%) (P< 0.001). Serum immunoglobulins levels were normal. The lack of secretory IgA and SC in the secretion could be related to the adherence capacity of the Candida albicans to epithelial cells.