Presence and nature of a glycocalyx-like coat on the external vesicular membrane of cysticercus cellulosae. A high resolution histochemical study.

Three histochemical techniques were used to demonstrate the presence of mucosubstances on the exposed surface of the vesicular membrane of $\text{Cysticercus cellulosae.}$ Using Alcian blue staining, electron micrographs revealed electron dense deposits of lanthanum confined to the entire exposed surface of the microthriches. Using concanavalin A, the results showed a discontinuous thin layer of electron dense deposits along the same exposed surface as the Alcian blue technique. Using colloidal iron hydroxide labelling, the electron micrographs showed the presence of negative charges along only the tips of the microthriches. This distribution of the negative charges is discussed and possible explanations are proposed. The conclusion from these results on both the presence of a surface glycocalyx-like coat rich in both acidic and neutral carbohydrates and the presence of a negative surface potential suggest that the exposed surface of $\text{Cysticercus cellulosae}$ may have important roles in the host-parasite interrelationships.     

Enhanced erythroid burst formation in mice after testosterone treatment

A single administration of testosterone propionate (TP) in ex-hypoxic polycythemic mice induces, at 24 hr after androgen, an amplification of the erythroid burst-forming unit (BFU-E or B) pool in marrow. This phenomenon is not associated with an amplification of the erythroid colony-forming unit (CFU-E or E) compartment and is followed by its depletion. In the other hand, the 36–49 hr rise of erythropoietin (Ep) levels in serum is followed by a 60-hr amplification of the E pool. It is suggested that the latter phenomenon is mediated by enhanced Ep production, whereas the early amplification of the B compartment may derive from a direct influence of TP at the stem cell level.     

Stereotyped behaviour after cholinergic, but not dopaminergic, stimulation of the substantia nigra in rats

Stereotyped behaviour of the rat was measured after intracerebral drug application in an objective and quantitative way by means of a new method developed in this laboratory. Bilateral intranigral injection of apomorphine /APO/, a specific dopaminergic agonist, did not evoke any signs of stereotyped behaviour. Also ineffective was the application of APO in the amygdaloid nucleus. Dopaminergic blockade of the substantia nigra by topical application of triperidol, a potent dopaminergic antagonist, failed to influence the stereotypy elicited by systematic APO administrationDirect cholinergic stimulation of the substantia nigra with carbachol resulted in a dose-related stereotyped behaviour not distinguishable by sight from that evoked by systematic APO administration. The effect of intranigral carbachol was antagonized by a previous intraperitoneal injection of 10 mg/kg of atropine. Stereotypy could easily be produced also by intracaudate application of APO. Topical triperidol blockade of the caudate nucleaus prevented the stereotypy caused by intraperitoneal application of APO.It is concluded that at least a part of nigral neurons cannot be directly excited by apomorphine. However, they can be excited by carbacol and seem thus, to contain muscarinic receptors. The stimulation of these receptors results in an excitation of the neurons involved and produces marked stereotyped behaviour.     

Isolation and properties of crystalline ferredoxin from lactuca sativa

Lettuce ferredoxin has been purified to homogeneity, with a yield of 18 mg/kg of denerved leaves. It crystallizes in magnificent needles, often clustered in broom-like sheaves. The absorption spectrum showed maxima at 460, 422, 330 and 274 nm,with a ratio A₄₂₂/A₂₇₄, of 0.46. The mM absorption coefficient was 9.74 at 422 nm, and 21.62 at 274 nm. This ferredoxin showed a pI = 4.7 and an E′₀ = ?425 mV (at pH = 7.7). MWs of 12 400, 11480 and 13000 were obtained by sucrose gradient centrifugation, and on the basis of the amino acid composition and the iron content, respectively, with an average of 12 300. The amino acid analysis showed the existence of one methionine residue per mole, with 105 amino acid residues. There are two iron atoms and two labile sulfide groups per mole; 4 half-cystine residues were found by performic acid oxidation, and 5 cysteine groups when determined by titration with pHMB. The native protein is not fixed on thiol-Sepharose 4B, but it is quantitatively retained after incubation with 8 M urea. Lettuce ferredoxin showed a 62, 58 and 78% effectiveness with the spinach ferredoxin-NADP reductase, nitrite reductase and fructose-1,6-diphosphatase (FDPase), respectively, when compared with the spinach ferredoxin. This different behaviour of both ferredoxins is joined to genetic-structural relationships, and suggests that the role of ferredoxin in FDPase activation is more sophisticated than that of a mere nonspecific reductant.     

Effect of propranolol on glycerol induced acute renal failure in rats

The effect produced by propranolol, administered for a prolonged period of time and in large doses, on renal function in rats has been studied, as well as the modifications induced by this treatment in an experimental model of acute renal failure, and the effects of a single dose of propranolol given 1 hour before provoking failure. Propranolol, administered chronically, causes sodium and water retention and increases creatinine clearance. Acute renal failure induced by glycerol in rats treated for 7 days with propranolol is less severe than the one produced in untreated animals. In this ARF model, a single dose of propranolol does not seem to have a protective effect.     

Aminoacid composition and hydrophobicity index of mitochondrial polypeptides

The aminoacid composition of protein stained bands in polyacrylamide gels, after electrophoresis of proteins from inner mitochondrial membranes, was investigated hydrolyzing directly the gel slices. The Hydrophobicity Index of 18 prominent polypeptide bands was calculated after their aminoacid analysis. The polypeptides less related to the membrane have low hydrophobicity as inferred from their Hydrophobicity Indexes.     

Ultrastructural effects of 6-hydroxy-dopamine and 5, 6-dihydroxytryptamine on the central nervous system of fresh-water mussel, Anodonta cygnea L

Ultrastructural effects of 6-hydroxydopamine and 5, 6-dihydroxytryptamine treatments were investigated in the central nervous system of fresh-water mussel. Two days after the treatments, the following characteristic find-structural alterations could be observed in the neuropil of the ganglia: frequent occurrence of multilamellar bodies, lysosomatic structures and elongated tubular forms; shrinking of varicose axon profiles with an enchancement of the density of the axoplasm and clumping of its content; abnormal swelling of certain axons in the neuropil. This degenerative process was accompanied by an intense phagocytosis. The damages evoked by the employed "false transmitters" in the mussel ganglia were, in general, similar to those found in vertebrates. Statistical analysis of the vesicle population of ganglia suggests the intragranular uptake of 6-hydroxydopamine and 5, 6-dihydroxytryptamine and, in addition, the role of dense-core vesicles of different types in the storage of both serotonin and catecholamines. Perikarya composing the cortical layer of the ganglia were not affected by the "false transmitters". This shows that different parts of a mussel neuron are differently sensitive to 6-hydroxydopamine and 5, 6-dihydroxytryptamine.     

Inducible α-glucosidase of Mucor rouxii: Effects of dimorphism on the development of the wall-bound activity

Some properties of the inducible α-glucosidase system of Mucor rouxii were investigated. This enzymatic activity was induced after resuspending glucose-grown cells in a maltose-supplemented medium. The wall-bound activity of α-glucosidase was determined by using intact cells in the enzymatic assay; this activity represented from 80 to 90% of the total activity present in the induced cells. The addition of glucose before, or during, the induction period repressed α-glucosidase synthesis. α-Glucosidase induction was tested under aerobic and anaerobic conditions. It was found that the enzyme synthesis and the appearance of wall-bound activity were not affected by changing the gaseous environment. On the other hand, it was observed that anaerobically grown yeast-like cells were much less efficient than aerobic mycelia to develop wall-bound α-glucosidase activity. This could explain earlier observations about the incapacity of M. rouxii to utilize maltose as a substrate for anaerobic growth. This idea was strengthened by the fact that, if an anaerobic culture was induced to develop under a mycelial morphology by adding to the medium the chemical agent EDTA, these cells also acquired the capacity to grow on maltose and concomitantly possessed wall-bound α-glucosidase activity. The relevance of the structure of the cell wall on the capacity of M. rouxii to metabolize maltose is discussed.