Relationships between cell surface protease and acid phosphatase activities ofLeishmania promastigote

A correlation between the ratio of the cell surface protease activity to phosphatase activity and the complexity of the pattern of cell surface exposed polypeptides ofLeishmania promastigotes was demonstrated for various strains grown under similar conditions. The ratio of the cell surface protease activity to acid phosphatase activity was high forL. major andL.b. panamensis and it correlates with the expression of a single polypeptide of 63 KDa on their cell surface. Intermediate and lower ratios of these enzymatic activites relate with more complex radio-iodinated patterns: two main bands inL.b. guyanensis (70 and 58 KDa) andL.b. braziliensis (72 and 60 KDa) and three main bands 65, 50, 27 KDa in allL.m. mexicana strains tested. Evidence is presented that the acid phosphatase located on theL.m. mexicana cell surface is not an artifact due to a secondary absorption of the secreted acid phosphatase from the culture medium. These results confirm theLeishmania antigen cell surface heterogeneity. The implications on the biology ofLeishmania and the clinical manifestation of leishmaniasis are discussed.     

Morphology, ontogeny and histochemistry of secretory trichomes of Geranium robertianum (Geraniaceae)

Geranium robertianum bears three types of glandular uniseriate trichomes which originate from a single protodermal cell and develop through periclinal divisions. Type I trichomes are procumbent and have an oval apical cell, two stalk cells and a basal cell. Type II trichomes are erect and have a pear shaped apical cell, two stalk cells and a basal cell. Type III trichomes are much longer than the other two types and have an elongated apical cell, five long stalk cells and a basal cell. Type I and type II trichomes are common on leaves while III trichomes are more abundant on flower structures.
Type I and type II trichomes secrete terpenoids and phenols. Type III trichomes are characterized by the accumulation of anthocyanins in the apical cell and secrete flavonoids.     

Binding of vinyl polymers to anionic model membranes.

The association of poly2-vinylpyridine (P2VPy) and poly4-vinylpyridine (P4VPy) to dimyristoylphosphatidic acid (DMPA) small unilamellar vesicles (SUVs) was studied as a function of pH, ionic strength (I), polymer concentration and temperature using spectrofluorimetry. Poly(vinylpyridine) (PVPy) data were transformed into association isotherms and analyzed in terms of binding and partition models. In the case of polyions, the inclusion of the activity coefficient in both models was essential. Moreover, a relating equation was proposed to compare parameters based on both theoretical approaches. On the basis of the results obtained, a model was developed to analyze polymer adsorption at the surface level, in which the length of the hydrophobic chain and the position of the N atom in the pyridinium ring play an important role. Transition temperature (Tc) for DMPA (ca. 55 degrees C) is decreased between 15 degrees C-19 degrees C in the presence of PVPy. Van't Hoff isochore showed that the binding constant (KA) accounted for average PVPy-DMPA two-dimensional solid and liquid interactions. KA decreased with I in the presence of both polymers, but was more sensitive to I in the case of P2VPy. Likewise, the number of phospholipid heads (N) involved in the binding process decreased with I in the presence of PVPy. The influence of I was more significant on N than on KA.     

Experimental tendon repair: glycosaminoglycan arrangement in newly synthesized collagen fibers.

Changes in the macromolecular orientation and metachromasy of glycosaminoglycans (GAG) in newly synthesized and assembled collagen fibers in rat Achilles tendon after tendon excision were investigated in toluidine blue (TB)-stained preparations, based in the selective absorption of polarized light (= linear dichroism, LD) and of absorption of unpolarized light in situ. Extrinsic LD was observed microspectrophotometrically from the early phases of tendon repair onwards, although the absorption peaks in both parallel and perpendicular directions with respect to the plane of polarized light and the long axis of the collagen fibers occurred at the same wavelength, and thus differed from the pattern situation in normal adult controls. Compared to normal adult tendons, the pattern of LD in newly synthesized and assembled fibers was still not fully attained 110 days after surgical tendon removal. This incomplete recovery possibly reflected the influence of aging during the repair process. There was no correlation between LD and metachromasy. The highest absorption values for metachromatic staining occurred on the 7th day after tendon removal, at a time when LD was not intense. Treatment with hyaluronidase showed that the LD in the early stages of tendon repair was mostly due to hyaluronate whereas the LD in the later stages was due to chondroitin sulfates. The changes in LD during Achilles tendon repair were attributed to gradual modifications in the composition and macromolecular orientation of GAGs relative to the long axis of the collagen fibers.     

In vitro micropropagation of the macarronesian evergreen treePersea indica (L.) K. Spreng

Summary Shoot propagation ofPersea indica (L.) K. Spreng was achieved using seedling axillary buds cultured on MS (Murashige and Skoog, 1962) medium with 1 mg/l (2.8 μM) N⁶-benzyladenine (BA). Forty percent of the obtained shoots did not elongate, but showed bud proliferation, which was maximal (three axillary buds per shoot) at the end of the seventh subculture. Sixty percent of the shoots elongated, did not show bud proliferation, and formed calluses at their base. Successful rooting (84.6%) was achieved dipping the base of each elongated shoot in 3 g/l (16.11 mM) indolebutyric acid (IBA) for 1–2 s, and transferring to half strength MS medium without growth regulators. These shoots presented an acclimatization success of 100%. Results suggest that micropropagated elongated shoots ofP. indica can be adequately used in reforestation programs.     

Identification of P-glycoprotein at the membrane of mast cell secretory granules. An immunofluorescence and protein A-gold electron microscopical investigation

The presence of P-glycoprotein has been investigated in rat peritoneal mast cells by means of immunofluorescence and immunogold electron microscopy, using the specific monoclonal antibody JSB-1. Immunofluorescence studi es showed that the glycoprotein is primarily concentrated in mast cell granules, and little is localized at the plasma membrane. Electron microscope observations revealed a marked accumulation of colloidal gold particles at the granule-coating membranes, whereas decoration of the plasma membrane is much less intense. When mast cells are stimulated to exocytate with compound 48/80, both immunofluorescence and electron microscopy showed concentration of P-glycoprotein reactivity at the plasma membrane level. Indeed, fusion of the granule with the plasma membrane allowed transfer of immunoreactive P-glycoprotein material from the granule-coating membrane to the cell surface membrane. These findings confirmed the presence of P-glycoprotein in mast cells; it is predominantly localized in the granules and is exposed on the cell surface only after exocytosis, suggesting, therefore, a possible physiological role for P-glycoprotein in the secretion of certain mediators. This revised version was published online in November 2006 with corrections to the Cover Date.     

The complete amino acid sequence of the major alpha subunit of the lectin from the seeds of Dioclea grandiflora (Mart)

The complete amino acid sequence of the major alpha subunit of the lectin from seeds of Dioclea grandiflora was determined. The sequence was deduced from analysis of peptides derived from the native alpha subunit by digestion with trypsin, chymotrypsin, the Staphylococcus aureus V8 protease, and pepsin; and from larger peptides produced by digestion of the citraconylated protein with trypsin. The alpha subunit consists of a single polypeptide chain of 237 amino acids which differs from the sequence of concanavalin in 53 positions. Significant levels of heterogeneity were observed in five positions in the sequence.     

Distribution of the genus Ancylostoma (Dubini, 1843) along the digestive tube of the dog (author's transl)

The A. A. studied the distribution of nematodes of the genus Ancylostoma (Dubini, 1843) along the digestive tube of 45 dogs. For the collection of the worms they used the method developed by Mello and Campos. The distribution found was: 97,5% in the jejunum, 1,2% in the ileon, 0,7% in the duodenum, 0,3% in the colon, 0,2% in the cecum and 0,1% in the stomach.