Ultrastructural localization of acid phosphatase in arbusculate coils of mycorrhizal Phoenix canariensis roots

Acid phosphatase (ACP) activity has been detected in roots of mycorrhizal and non-mycorrhizal Phoenix canariensis. This enzyme was ultrastructurally localized in arbusculate coils for the first time. This localization was carried out using a cerium-based method, which minimizes non-specific precipitation. The ACP was localized in inter- and intracellular hyphae, in the fungal cytoplasm as well as at the interface and the fungal cell wall and the periarbuscular membrane limiting it. The novel localization of an ACP in the arbuscular mycorrhizal (AM) interface of arbusculate coils suggests that this enzyme may be involved in the phosphorus efflux from the mycorrhizal fungus to the host. The results presented in this article indicate that the role played by ACP in AM symbiosis may be more important than was previously thought and that arbusculate coils are highly relevant when considering nutrient transfer through AM symbiosis.

Diverse effects of c-src deficiency on molar tooth development and eruption in mice

C-src deficiency is characterized by osteopetrosis due to impaired bone resorption by hypofunctional osteoclasts and the resultant failure of tooth eruption. In preliminary observations, we frequently encountered erupted molars in c-src deficient mice unlike in other osteopetrotic animals. Here we examine the effects of c-src deficiency on the development of molar teeth with an emphasis on the spatial relation of growing teeth with the surrounding bones. In c-src deficient mice, the magnitude of tooth impaction differed considerably among the types of molars; all maxillary 1st molars were totally impacted deep in the alveolar sockets, whereas most mandibular 1st molars fully erupted into oral cavity. Distribution of osteoclasts in the alveolar bone was identical among all types of molars, and electron microscopy revealed signs of bone resorbing activity in these osteoclasts despite the absence of a ruffled border. From early development, the alveolar space was much narrower in the upper molar tooth germs than in the lower ones in both wild type and homozygous animals, and particularly so in the upper 1st molars. Current observations thus indicate a significant contribution of "hypofunctional osteoclasts" in c-src deficient mice in molar tooth development except for the upper 1st molars, which appear to require highly functional osteoclasts to gain sufficient space for them to grow normally. Taken together, these findings on the seemingly tooth-type specific effects of c-src deficiency on the development and eruption of molar teeth in c-src deficient mice can be attributed to the given differential spatial relation of the respective tooth germs with the surrounding bones in the presence of hypofunctional osteoclasts.

Extracellular breakdown of collagen by mice decidual cells. A cytochemical and ultrastructural study

The interaction of antimesometrial decidual cells and collagen fibrils was studied by light microscopy and ultrastructural cytochemistry in fed and acutely fasted mice on days 9-11 of pregnancy. Fibrillar elements in the extracellular space consisted of collagen fibrils and filamentous aggregates (disintegrating collagen fibrils). Intracellular vacuoles exhibited typical collagen immersed in electron-translucent material (clear vacuoles) and faint cross-banded collagen immersed in electron-opaque material (dark vacuoles). Fibrillar elements showed extracellular acid phosphatase activity which was stronger in the region of mature decidua than in predecidual cells region in all animals; it was conspicuous in mature decidua of fasted animals. Intracellular acid phosphatase activity was observed in dark vacuoles and lysosomes, and was absent in clear vacuoles in all cells studied. Since acid phosphatase activity reflects the presence of lysosomal hydrolases in general, the results indicate that breakdown of extracellular collagen occurs by release of lysosomal enzymes by decidual cells and also by internalization of collagen for intracellular degradation in fed and fasted mice. Collagen breakdown may be part of the process of tissue remodeling in mature and predecidual regions, however, in mature decidua, collagen breakdown is enhanced and may therefore contribute to nutrition of the fetus, specially in acutely fasted mice.

A morphological and cytochemical study of the interaction between Paracoccidiodes brasiliensis and neutrophils

Paracoccidioidomycosis is a systemic granulomatous disease caused by the dimorphic fungus Paracoccidioides brasiliensis. It is the most prevalent systemic mycosis of Latin America and 80% of the reported cases are from Brazil. Because of the great number of neutrophils found in the P. brasiliensis granuloma, studies have been done to evaluate the role of these cells during the development of the infection. Scanning and transmission electron microscopy of thin sections showed that the neutrophils ingest yeast cells through a typical phagocytic process with the formation of pseudopodes. The pseudopodes even disrupt the connection established between the mother and the bud cells. Neutrophils also associate to each other, forming a kind of extracellular vacuole where large yeast cells are encapsulated. Cytochemical studies showed that once P. brasiliensis attaches to the neutrophil surface, it triggers a respiratory burst with release of oxygen-derived products. Attachment also triggers neutrophils degranulation, with release of endogenous peroxidase localized in cytoplasmic granules. Together, these processes lead to killing of both ingested and extracellular P. brasiliensis.

Fine structural and cytochemical observations of dental epithelial cells during the enameloid formation stages in red stingrays Dasyatis akajei

The fine structure and the localization of nonspecific acid phosphatase (ACPase), nonspecific alkaline phosphatase (ALPase), and calcium-dependent adenosine triphosphatase (Ca-ATPase) activities in the dental epithelial cells in tooth germs of Dasyatis akajei in the later stages of enameloid formation were investigated. Numerous invaginations of the distal cell membrane of the inner dental epithelial (IDE) cells were observed at the early stage of enameloid maturation. The invaginations contain many fine granular and filamentous substances; the lamina densa, which was thicker during the former stages, is obscure. Granules exhibiting defined ACPase activity were usually found in the IDE cells during the stages of enameloid mineralization and maturation. IDE cells are putatively involved in the removal of degenerated enameloid matrix during these stages. Marked ALPase activity was detected at the proximal and the lateral cell membranes of the IDE cells from the late stage of enameloid matrix formation to the early stage of enameloid maturation. Strong activity of Ca-ATPase was localized at the proximal and the lateral cell membranes of the IDE cells during the stages of enameloid mineralization and maturation. ALPase and Ca-ATPase activity is probably related to crystal formation in the enameloid and the removal of degenerated enameloid matrix from the enameloid.

Structure of a filamentous phosphoglycoprotein polymer: the secreted acid phosphatase of Leishmania mexicana

The insect stage of the protozoan parasite Leishmania mexicana secretes a filamentous acid phosphatase (secreted acid phosphatase, SAP), a polymeric phosphoglycoprotein. The wild-type (wt) SAP filament is a copolymer composed of two related gene products SAP1 and SAP2, which are identical in the enzymatically active NH2-terminal domain and the COOH-terminal domain, but differ in the length of a highly glycosylated Ser/Thr-rich repeat region (32 amino acids and 383 amino acids, respectively) which is located between these domains. When expressed separately, full length SAP1, SAP2, or the NH2-terminal domain alone, are able to assemble into filaments. The Ser/Thr-rich region is the exclusive target for a novel type of O-glycosylation via phosphoserines. By using glycerol spraying/low-angle rotary metal shadowing and labelling with monoclonal antibodies it is demonstrated that the repetitive region adopts an extended conformation forming side arms which project radially from the filament core and terminate with the COOH-terminal domain. The length of the side arms of SAP1 and SAP2 (20 nm and 90 nm, respectively) corresponds to the predicted length of the Ser/Thr-rich repeat region of SAP1 and SAP2. Mass determination by scanning electron microscopy (STEM) shows that one morphologically defined globular particle of the filament core is a polypeptide dimer. We propose a model for the filament core, in which the globular NH2-terminal SAP domains form one strand composed of polypeptide dimers or two tightly associated strands of monomers which may twist into a double helix, similar to actin filaments. The highly O-glycosylated side arms project from the filament core conferring an overall bottle-brush-like appearance. The L. mexicana SAP is compared to SAPs secreted by the closely related species L. amazonensis and L. donovani.

Acid phosphatase activity in Perkinsus marinus, the protistan parasite of the American oyster, Crassostrea virginica

The effect of temperature (4, 12, 20, and 28 C) and osmolality (400, 570, and 840 mOsm/kg) on extracellular acid phosphatase (AP) secretion in vitro, and ultrastructural localization of AP activity in the parasite were investigated. The extracellular AP secretion by Perkinsus marinus was cell density dependent (P < 0.001). Increasing culture temperatures resulted in increased P. marinus proliferation concomitant with AP secretion (P < 0.0001). AP secretion was similar in P. marinus cultured at 400 and 570 mOsm/kg media, but higher than P. marinus cultured at 870 mOsm/kg media. Results of the ultrastructural study revealed that intense AP activity was in the nucleus of the parasite. Based on its distribution in the nucleus, AP may be playing a role in events leading to cell cycle regulation.

Relationship of acid phosphatase activity to ultrastructural features in mice inoculated with Mycobacterium paratuberculosis

Macrophage activation, measured as increased acid phosphatase (AcPase)-positive areas by image analysis, and ultrastructural features were examined in granulomatous mycobacterial lesions of mice innately susceptible (BALB/c mice; Bcg) and innately resistant (C3H/HeJ mice; Bcg) to Mycobacterium paratuberculosis strain ATCC 19698. In the liver and spleen of BALB/c mice 3 weeks after intraperitoneal inoculation with M. paratuberculosis, AcPase activity detected in epithelioid cell nodules was high; it had decreased, however, in the liver and spleen after a further 3 and 6 weeks, respectively. In C3H/HeJ mice, the size of epithelioid cell nodules in the liver and spleen was smaller than in BALB/c mice, and infiltrating macrophages, which had increased by week 9 after inoculation, showed high AcPase activity. Ultrastructurally, by week 32 in BALB/c mice, small phagolysosomes (SPLs) had greatly increased in number in the epithelioid cells. These SPLs contained a few AcPase-positive areas and a small number of bacteria, most of which were surrounded by an electron-translucent space (or electron-transparent zone [ETZ]). In contrast, only a few SPLs were observed in C3H/HeJ mice at week 32; in the liver and spleen, large phagolysosomes (LPLs) showed high AcPase activity and contained many degenerated bacteria, which also had an ETZ. These results suggest that the enzymatic and ultrastructural differences in phagolysosomes between BALB/c mice and C3H/HeJ mice reflect the susceptibility of these mouse strains to M. paratuberculosis.

[Analysis of the quaternary structure of secreted repressible acid phosphatase from the yeast Saccharomyces cerevisiae]

The structural organization of extracellular repressible acid phosphatase from S. cerevisiae has been studied. The existence of multiple acid phosphatase forms with isoelectric points at pH 4.1-4.8 has been confirmed by isoelectrofocusing. The molecular masses of three acid phosphatase isoforms (56, 57-59, and 60 kDa) obtained after enzymatic deglycosylation correlate with the data obtained previously during the analysis of translation products in cell-free systems. Electron microscopic studies revealed that the acid phosphatase molecule has a square shape and is made up of four identical subunits with molecular masses of about 125 kDa.

1H NMR and NOE studies of the purple acid phosphatases from porcine uterus and bovine spleen

The diiron active sites of the purple acid phosphatases from porcine uterus (also called uteroferrin, Uf) and bovine spleen (BSPAP) and their complexes with tungstate are compared by 1H NMR and NOE techniques. The paramagnetically shifted features of the 1H NMR spectrum of reduced BSPAP are similar to those of reduced Uf, while the spectra of the tungstate complexes are almost identical. These observations suggest that the two active sites are quite similar, in agreement with the greater than 90% sequence homology found in the two enzymes. Nuclear Overhauser effect (NOE) experiments on the His N-H resonances show that the Fe(III)-His residue is N epsilon-coordinated, while the Fe(II)-His is H delta-coordinated in both enzymes. On the basis of the above NMR and NOE results, our previously proposed model for the dinuclear iron active site of Uf [Scarrow, R. C., Pyrz, J. W., & Que, L., Jr. (1990) J. Am. Chem. Soc. 112, 657-665] is corroborated, refined, and found to represent the diiron center of BSPAP as well.

Ultrastructural localization of alkaline and acid phosphatase activities in dental plaque

Ultrastructural cytohistochemical techniques showed presence of acid and alkaline phosphatases in dental plaque. Both phosphatases had intra- and extramicrobial localization. In the extracellular matrix, phosphatases were associated with small vesicles of bacterial origin, or were freely scattered in the matrix without apparent connection with microbial structures. Intracellularly, alkaline (AlkP) and acid (AcP) phosphatases were observed in Gram-negative and Gram-positive bacteria, showing a different localization. The AlkP was mainly located in the periplasmic space, while AcP had a double preferential localization: along the outer surface of the cell wall and in the periplasmic space. Less frequently an intracellular phosphatase reaction was seen in the cytoplasm.

Co-localization of an endocytic marker and acid phosphatase in a tubular/reticular compartment in macrophages

Cultured resident murine macrophages are incubated in the continuous presence of the fluorescent endocytic marker Lucifer Yellow and a phorbol ester that activates protein kinase C. Under these steady-state labeling conditions the fluorescent tracer was, for the most part, in a tubular/reticular compartment. Enzyme cytochemical localization of acid phosphatase in the same cells showed essentially a one-to-one correlation between the Lucifer Yellow- and acid phosphatase-containing compartments. Procedures for epifluorescence observation and subsequent enzyme cytochemical examination of the same whole mount cells are described. In addition, chemical fixation methods for the preservation of this labile tubular/reticular compartment are presented.