摘要:

ABSTRACT.Euplotidium itoishare with some other species of the same genus a peculiar feature: the presence of a band of particles running along the right and left borders of the cell body and forming a sort of “scarf” at the dorsal anterior end. The ultrastructural analysis, here performed, revealed that these particles (reported in the literature as extrusomes) are always external to the cell and are inserted in matching depressions on the euplotidium cortex. They are present in two different forms: type I, whose ultrastructure recalls that of bacteria, are able to reproduce by binary fission; type II are not able to divide and contain peculiar structures (a granular dome‐shaped zone, a complex extrusive apparatus and a network of regularly arranged fibrils) which render them more complicated with respect to the majority of prokaryotic organisms. These observations, together with the finding that these particles contain DNA, indicate that we are dealing with epibionts, that will be referred to as “epixenosomes” (ecto‐organisms), rather than extrusomes. Some ideas about the nature of “epixenosomes” and their relationship with the host cell are propose

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01155.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.In the ciliateGlaucoma scintillans, the process of transformation of unbalanced homopolar doublets to singlets was investigated. Cells were fixed 1–3 days after inoculation and impregnated with silver according to the Chatton‐Lwoff technique. The two oral apparatuses (OAs) approached each other partly due to a loss of ciliary rows in one of the two components (semicells) consisting of a doublet. The contractile vacuole pore (CVP) in the narrow semicell (sc1) was lost at an early stage of regulation, while the position of CVP in the broad semicell (sc2) shifted toward the right after the loss of sc1. The sc1 of 20 row‐intervals in breadth was a transition point above which the sc1 was able to persist for awhile, and beneath which it was actively lost. There was no evidence for an independent effect of sc2 on the transformation of doublets to singlets. In cell division, an additional reversed oral primordium (sOP) was formed in unbalanced doublets, usually within a narrow sc1 of 11–20 row‐intervals. The position of the sOP was generally 4–6 row‐intervals distant from the right side of the oral meridian (OM1) with the cell's left OA. Most of the doublets with an sOP lacked an oral primordium in the OM1. No mature triplet with 2 normal OAs and an abnormal OA was found in these preparations. The pathway of regulation, the movement of the CVP, and the formation of an sOP

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01156.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.In this paper we show that murine lung conditioned medium (LCM) displays, in addition to its already described colony‐stimulating activity on bone marrow cells, a potent growth‐stimulating activity on promastigotes ofLeishmania mexicana amazonensis. Immunoprecipitation of LCM with an antibody specific for murine granulocyte‐macrophage colony stimulating factor (GM‐CSF) abrogates both activities, indicating that the leishmanial growth‐promoting activity is due to the presence of GM‐CSF on LCM. Furthermore, recombinant GM‐CSF (rGM‐CSF) added to the culture medium or to the immunoprecipitated LCM is able to respectively induce or to partially recover the growth‐promoting activity of the LCM. Sequential in vitro passages of the parasite induces a progressive loss of sensitivity to the growth‐factor. Parasite forms recently collected from lesions are significantly more responsive to the growth‐factor than forms already adapted to grow in culture. Since it has been shown that several different microorganisms display receptors for vertebrate‐like hormones and that GM‐CSF is able to enhance a cutaneous leishmanial lesion, our results permit us to raise the hypothesis that a direct interaction between a host‐derived hormone and a pathogenic microorganism can be of importance in defining the fate of an infection. The fact that GM‐CSF is produced by cells that actively participate in a leishmanial infection (T‐lymphocytes and macroph

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01157.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Methotrexate (MTX) coupled to mannosyl bovine serum albumin (BSA) was taken up efficiently through the mannosyl receptors present on macrophages. Binding experiments indicate that conjugation does not decrease the affinity of the neoglycoprotein for its cell surface receptor. The drug conjugate eliminated intracellular amastigotes ofLeishmania donovaniin mouse peritoneal macrophages about 100 times more efficiently than free drug on the basis of 50% inhibitory dose. Inhibitory effect of the conjugate was directly proportional to the density of sugar on the neoglycoprotein carrier. Colchicine and monensin, inhibitors of receptor‐mediated endocytosis, can prevent the leishmanicidal effect of the conjugate. Antileishmanial effect of the conjugate can be competitively inhibited by mannose‐BSA and mannan. In a murine model of experimental visceral leishmaniasis the drug conjugate reduced the spleen parasite burden by more than 85% in a 30‐day model whereas the same concentration of free drug caused little effect. These results indicate that MTX‐neoglycoprotein conjugate binds specifically to macrophages, and is internalized and degraded in lysosomes releasing the active drug to act onLeishmaniaparasites. These results also represent the potential for a general approach to intracellular targeting of clinical agents for macrophage‐associated

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01158.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.A new species of ascetosporan parasitizing tissues of woodboring mollusks of the genusTeredo, includingT. navalisLinnaeus,T. furciferavon Martens, andT. bartschiClapp, is described from light and transmission electron microscopical observations. The new species is assigned the nameMinchinia teredinissp. n. (Phylum Ascetospora, Class Stellatosporea, Order Balanosporida, Family Haplosporidiidae). Plasmodia, sporonts, sporocysts, and mature spores are found in all host tissues, but primarily in the gill. Spores are obovate, operculate, and characterized by four projections from the epispore membrane. The species is found from Long Island Sound to Virginia on the east coast of the United States. The parasite causes extensive damage to host tissues and is correlated with reductions in host populations.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01159.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.A diplomonad flagellate,Spironucleus torosan. sp. is described from Atlantic CodGadus morhuaand haddockMelanogrammus aeglefinus. This is believed to be the 1st confirmed report ofSpironucleusfrom a marine fish. Organisms swimming in the rectal lumen were broadly pyriform to elongate, and measured 10.5–18.6 μm long and 3.2–13.3 μm wide; other elongate organisms were attached to the rectal epithelium, via apical extensions appearing continuous with the microvilli. The posterior end of the body was extended into a caudal projection, on either side of which was a posteriolateral ring‐shaped protrusion or torus, with a recurrent flagellum emerging from its centre. A symmetrical system of microtubules and lamellae, forming a “V” in protargol impregnated specimens, supported the flanges of the body surrounding the tori, the tori themselves and the caudal projection. Supranuclear microtubules were an inverted V to U shape in transverse section, and an electron dense band accompanied the cytostomes. Lightly staining homogenous cytoplasm was usually present in the anterior part of the body, the remainder being highly vacuolated with numerous dark granules. In swimming organisms, rough endoplasmic reticulum (RER) was present around the nuclei and cytostomes, and bacteria were occasionally seen in the cytoplasm. In “attached” organisms, RER was reduced, and bacteria were absent.Hexamita salmonisMoore fromSalvelinus fontinaliswas studied by light and scanning electron microscopy for comparison; its cytoplasm was not highly vacuolated. The two recurrent flagella emerged close together from the blunt posterior

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01160.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Trichomonas vaginalisandTritrichomonas foetuscontain glucokinase and not a hexokinase of broad hexose specificity.Tritrichomonas foetusalso contains a specific fructokinase which could be resolved from glucokinase by anion exchange chromatography. NativeT. vaginalisglucokinase had a Mr of 76,000, and SDS‐PAG electrophoresis showed two equally stained bands corresponding to Mr 40,000 and 38,000. Glucose and ATP were by far the best substrates for both trichomonad glucokinases, with Km values as low as 33–35 μM and 75–83 μM, respectively. Substrate saturation curves for these enzymes were all hyperbolic.Tritrichomonasfoetus fructokinase required fructose and ATP, with Km values of 200 μM and 81 μM. None of the activities was affected by a number of potential regulatory metabolites, including glucose‐6‐phosphate. The only exception was AMP which in supraphysiological concentrations had an inhibitory effect onT. foetusfructokinase. In conclusion, the absence of regulation at the hexose phosphorylation step described here, as well as the presence of an easily reversible PPi: fructose‐6‐phosphate 1 ‐phosphotransferase described previously (Mertens, E., Van Schaftingen, E.&Müller, M. 1989.Mol. Biochem. Parasitol.,37:183–190), suggest that the rate of the 1st part of glycolysis in trichomonads is controlled only by the intracellular a

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01161.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Mice infected with the protozoan parasiteTrypanosoma cruzi, the causative agent of human Chagas’disease, develop immunosuppressed responses to heterologous antigens. Experiments were performed using infected mice in the acute stage of infection to assess immunoregulatory activities during induction of direct plaque‐forming cells (DPFC) to sheep erythrocytes (SRBC), hapten‐conjugated SRBC (TNP‐SRBC), and horse erythrocytes (TNP‐HRBC). Studies in vivo demonstrated that anti‐SRBC responses were best enhanced whenT. cruz‐infected mice were injected with primed T cells derived from normal or infected mice immunized four days previously. The presence of enhancing capacities for DPFC responses by T cells fromT. cruzi‐infected mice were also supported by experiments examining the hapten‐carrier effect. Preimmunization of infected mice with SRBC or HRBC four days before injection of hapten‐homologous (TNP‐SRBC or TNP‐HRBC) carrier resulted in markedly augmented anti‐hapten antibody responses. These results show that functional help provided by T cells activated during priming and exposed to a challenge dose of antigen (SRBC) in a time‐dependent mode can overcome the effect of immunosuppressi

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01162.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.The sera of 21 different species of primates were surveyed for the presence of a trypanocidal factor to a monomorphic human serum‐sensitive clone ofTrypanosoma brucei gambiense (T.b.g.); human, gorilla, baboon (2 species), and the mandrill were found to contain this factor. The factor in all the sera is in the high density lipoprotein (HDL) fraction, and has similar modes of biological action. It has been shown that the human and gorilla trypanocidal factor share cross‐reactive antigenic epitopes, but do not share similar cross‐reactive epitopes with the baboon and mandrill factor. There was no relationship between the presence or absence of this factor and the primate's position on the phylogenetic tree. In addition, there was also no obvious correlation between the animals’preferred diet, and the presence or absence of trypanocidal activity. The evidence to date suggests that only African ground‐dwelling primates that live in tsetse endemic areas contain the trypanocidal factor. It is assumed that this factor is involved in resistance of these primates toT.b.b.We believe that the host has developed trypanocidal substances as a result of selective evolutionary pressure by the African try

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01163.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.We have constructed a molecular karyotype for two strains ofNaegleria gruberiusing pulsed field gel electrophoresis. Each strain has about 23 chromosomes, considerably more than any previous estimate. These chromosomes range in size from 400 kilobasepairs to over 2,000 kilobasepairs. InNaegleria, construction of the DNA karyotype depends on assessment of the anomalous electrophoretic mobility of the circular ribosomal RNA genes. We have determined the chromosomal locations of an identified unique gene (flagellar calmodulin) and four identified multigene families (α‐ and β‐tubulin, actin, ubiquitin), as well as three differentially expressed genes of unknown functions. The ca. 12 actin genes are dispersed over at least seven chromosomes, whereas the majority of the more than eight α‐tubulin genes are confined to a single chromosome. The ubiquitin genes are found on five chromosomes in one strain and seven in the other and the β‐tubulin genes are on three or four. Our observations provide a foundation for molecular genetic studies in th

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01164.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY