Characterization of phosphoglycan-containing secretory products ofLeishmania

Parasitology ◽  
1994 ◽  
Vol 108 (S1) ◽  
pp. S63-S71 ◽  
Author(s):  
T. Ilg ◽  
Y.-D. Stierhof ◽  
M. Wiese ◽  
M. J. McConville ◽  
P. Overath
Keyword(s):  
Parasitophorous Vacuole ◽  
Secretory Product ◽  
Flagellar Pocket ◽  
Lesion Development ◽  
Causative Agents ◽  
Secretory Products ◽  
Species Specific ◽  
Modify Protein

SUMMARYThis article presents an overview on phosphoglycan-containing components secreted by the insect and mammalian stages of several species ofLeishmania, the causative agents of leishmaniasis in the Old and New World. Firstly, promastigotes of all three species considered,L. mexicana, L. donovaniandL. major, shed lipophosphoglycan (LPG) into the culture medium possibly by release of micelles from the cell surface. Like the cell-associated LPG, culture supernatant LPG is arhphiphilic and composed of a lysoalkylphosphatidylinositol-phosphosaccharide core connected to species-specific phosphosaccharide repeats and oligosaccharide caps. Secondly, all three species release hydrophilic phosphoglycan. Thirdly, all three species appear to secrete proteins covalently modified by phosphosaccharide repeats and oligosaccharide caps. In the case of promastigotes ofL. mexicana, these components are organized as two filamentous polymers released from the flagellar pocket: the secreted acid phosphatase (sAP) composed of a 100 kDa phosphoglycoprotein and a protein- containing high-molecular-weight-phosphoglycan (proteo-HMWPG) and fibrous networks likewise composed of phosphoglycan possibly linked to protein. Structural analyses and gene cloning suggest that the parasites can covalently modify protein regions rich in serine and threonine residues by the attachment of phosphosaccharide repeats capped by oligosaccharides. We propose that the networks formedin vitrocorrespond to fibrous material previously demonstrated in the digestive tract of infected sandflies. In the case ofL. donovani, the sAP is also modified by phosphoglycans but contains neither proteo-HMWPG nor does it aggregate to filaments. Finally,L. mexicanaamastigotes release proteo-HMWPG via the flagellar pocket into the parasitophorous vacuole of infected macrophages. This material appears to be released into the tissue of the infected mammal upon rupture of infected macrophages during lesion development. This secretory product may contribute to the pathology of lesion development.

scholarly journals A rapid, parasite-dependent cellular response to Dirofilaria immitis in the Mongolian jird (Meriones unguiculatus)

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Christopher C. Evans ◽  
Katherine M. Day ◽  
Yi Chu ◽  
Bridget Garner ◽  
Kaori Sakamoto ◽  
...  
Keyword(s):  
Cellular Response ◽  
Dirofilaria Immitis ◽  
Cell Attachment ◽  
Early Response ◽  
Meriones Unguiculatus ◽  
Filarial Parasite ◽  
Immune Mediated ◽  
Secretory Products ◽  
Species Specific

Abstract Background The Mongolian jird (Meriones unguiculatus) has long been recognized as a permissive host for the filarial parasite Brugia malayi; however, it is nonpermissive to another filarial parasite, canine heartworm (Dirofilaria immitis). By elucidating differences in the early response to infection, we sought to identify mechanisms involved in the species-specific clearance of these parasites. We hypothesized that the early clearance of D. immitis in intraperitoneal infection of the jird is immune mediated and parasite species dependent. Methods Jird peritoneal exudate cells (PECs) were isolated and their attachment to parasite larvae assessed in vitro under various conditions: D. immitis and B. malayi cultured separately, co-culture of both parasites, incubation before addition of cells, culture of heat-killed parasites, and culture with PECs isolated from jirds with mature B. malayi infection. The cells attaching to larvae were identified by immunohistochemistry. Results In vitro cell attachment to live D. immitis was high (mean = 99.6%) while much lower for B. malayi (mean = 5.56%). This species-specific attachment was also observed when both filarial species were co-cultured, with no significant change from controls (U(9, 14) = 58.5, p = 0.999). When we replicated these experiments with PECs derived from jirds subcutaneously infected with B. malayi, the results were similar (99.4% and 4.72% of D. immitis and B. malayi, respectively, exhibited cell attachment). Heat-killing the parasites significantly reduced cell attachment to D. immitis (mean = 71.9%; U(11, 14) = 7.5, p < 0.001) while increasing attachment to B. malayi (mean = 16.7%; U(9, 15) = 20, p = 0.002). Cell attachment to both species was reduced when larvae were allowed a 24-h pre-incubation period prior to the addition of cells. The attaching cells were identified as macrophages by immunohistochemistry. Conclusions These results suggest a strongly species-dependent response from which B. malayi could not confer protection by proxy in co-culture. The changes in cell attachment following heat-killing and pre-incubation suggest a role for excretory/secretory products in host immune evasion and/or antigenicity. The nature of this attachment is the subject of ongoing study and may provide insight into filarial host specificity.

Characterization of excretory–secretory products from protoscoleces of Echinococcus granulosus and evaluation of their potential for immunodiagnosis of human cystic echinococcosis

Parasitology ◽  
2004 ◽  
Vol 129 (3) ◽  
pp. 371-378 ◽  
Author(s):  
D. CARMENA ◽  
J. MARTÍNEZ ◽  
A. BENITO ◽  
J. A. GUISANTES
Keyword(s):  
Echinococcus Granulosus ◽  
Cystic Echinococcosis ◽  
Secretory Protein ◽  
Major Protein ◽  
Healthy Donors ◽  
Secretory Products ◽  
Protein Components ◽  
Human Cystic Echinococcosis

This study describes, for the first time, the characterization of excretory–secretory antigens (ES-Ag) from Echinococcus granulosus protoscoleces, evaluating their usefulness in the immunodiagnosis of human cystic echinococcosis. ES-Ag were obtained from the first 50 h maintenance of protoscoleces in vitro. This preparation contained over 20 major protein components which could be distinguished by 1-dimensional SDS–PAGE with apparent masses between 9 and 300 kDa. The culture of of protoscoleces from liver produced a greater variety of excretory–secretory protein components than those from lung. Determination of enzymatic activities of secreted proteins revealed the presence of phosphatases, lipases and glucosidases, but no proteases. These findings were compared to those obtained from somatic extracts of protoscoleces and hydatid cyst fluid products. Immunochemical characterization was performed by immunoblotting with sera from individuals infected by cystic echinococcosis (n=15), non-hydatidic parasitoses (n=19), various liver diseases (n=24), lung neoplasia (n=16), and healthy donors (n=18). Antigens with apparent masses of 89, 74, 47/50, 32, and 20 kDa showed specificity for immunodiagnosis of human hydatidosis. The 89 and 74 kDa components corresponded to antigens not yet described in E. granulosus, whereas proteins of 41–43 kDa and 91–95 kDa were recognized by the majority of the non-hydatid sera studied.

scholarly journals Invertebrate Gonadotropin-Releasing Hormone Receptor Signaling and Its Relevant Biological Actions

2020 ◽  
Vol 21 (22) ◽  
pp. 8544
Author(s):  
Tsubasa Sakai ◽  
Tatsuya Yamamoto ◽  
Shin Matsubara ◽  
Tsuyoshi Kawada ◽  
Honoo Satake
Keyword(s):  
Signal Transduction ◽  
Biological Functions ◽  
Hpg Axis ◽  
Intracellular Calcium Mobilization ◽  
Releasing Factors ◽  
Species Specific ◽  
Gonadotropin Releasing Hormone Receptor

Gonadotropin-releasing hormones (GnRHs) play pivotal roles in reproduction via the hypothalamus-pituitary-gonad axis (HPG axis) in vertebrates. GnRHs and their receptors (GnRHRs) are also conserved in invertebrates lacking the HPG axis, indicating that invertebrate GnRHs do not serve as “gonadotropin-releasing factors” but, rather, function as neuropeptides that directly regulate target tissues. All vertebrate and urochordate GnRHs comprise 10 amino acids, whereas amphioxus, echinoderm, and protostome GnRH-like peptides are 11- or 12-residue peptides. Intracellular calcium mobilization is the major second messenger for GnRH signaling in cephalochordates, echinoderms, and protostomes, while urochordate GnRHRs also stimulate cAMP production pathways. Moreover, the ligand-specific modulation of signal transduction via heterodimerization between GnRHR paralogs indicates species-specific evolution in Ciona intestinalis. The characterization of authentic or putative invertebrate GnRHRs in various tissues and their in vitro and in vivo activities indicate that invertebrate GnRHs are responsible for the regulation of both reproductive and nonreproductive functions. In this review, we examine our current understanding of and perspectives on the primary sequences, tissue distribution of mRNA expression, signal transduction, and biological functions of invertebrate GnRHs and their receptors.

scholarly journals Sensitivity of micromycetes of the genus Fusarium Link, causative agents of rot of the core of apple fruits, to the active substances of modern fungicides

2021 ◽  
Vol 39 ◽  
pp. 04005
Author(s):  
Galina Yakuba ◽  
Irina Astapchuk ◽  
Andrey Nasonov
Keyword(s):  
Relative Sensitivity ◽  
Causative Agents ◽  
Biological Effectiveness ◽  
Different Strains ◽  
Species Specific ◽  
Specific Reactions ◽  
Very High ◽  
Active Substances ◽  
Apple Fruits

As a result of the studies, species-specific reactions of strains of the genus Fusarium Link of relative sensitivity to the active substances of chemical fungicides, in vitro, were noted. The drugs showed both very high biological effectiveness (BE) (100%) and very low (0 %). In suppressing the species F. sporotrichioides, the best result was shown by a mixed preparation based on fluopyram and pyrimethanil, as well as single-component - mefentrifluconazole and cyprodinil, for the species F. oxysporum - all three mixed preparations: fluopyram + pyrimethanil; tebuconazole + fluopyram and thiram + difenoconazole. It can be preliminarily concluded that the same active substances and their mixtures exhibit unequal activity against different strains of the same species from the genus Fusarium, the causative agent of apple core rot.

scholarly journals Proteomics on the rims: insights into the biology of the nuclear envelope and flagellar pocket of trypanosomes

Parasitology ◽  
2012 ◽  
Vol 139 (9) ◽  
pp. 1158-1167 ◽  
Author(s):  
MARK C. FIELD ◽  
VINCENT ADUNG'A ◽  
SAMSON OBADO ◽  
BRIAN T. CHAIT ◽  
MICHAEL P. ROUT
Keyword(s):  
Nuclear Envelope ◽  
Cell Biology ◽  
Drug Targets ◽  
Surface Glycoprotein ◽  
Flagellar Pocket ◽  
Genome Sequences ◽  
Causative Agents ◽  
Higher Eukaryotes ◽  
The Many

SUMMARYTrypanosomatids represent the causative agents of major diseases in humans, livestock and plants, with inevitable suffering and economic hardship as a result. They are also evolutionarily highly divergent organisms, and the many unique aspects of trypanosome biology provide opportunities in terms of identification of drug targets, the challenge of exploiting these putative targets and, at the same time, significant scope for exploration of novel and divergent cell biology. We can estimate from genome sequences that the degree of divergence of trypanosomes from animals and fungi is extreme, with perhaps one third to one half of predicted trypanosome proteins having no known function based on homology or recognizable protein domains/architecture. Two highly important aspects of trypanosome biology are the flagellar pocket and the nuclear envelope, where in silico analysis clearly suggests great potential divergence in the proteome. The flagellar pocket is the sole site of endo- and exocytosis in trypanosomes and plays important roles in immune evasion via variant surface glycoprotein (VSG) trafficking and providing a location for sequestration of various invariant receptors. The trypanosome nuclear envelope has been largely unexplored but, by analogy with higher eukaryotes, roles in the regulation of chromatin and most significantly, in controlling VSG gene expression are expected. Here we discuss recent successful proteomics-based approaches towards characterization of the nuclear envelope and the endocytic apparatus, the identification of conserved and novel trypanosomatid-specific features, and the implications of these findings.

Partial characterization of proteolytic enzymes in different developmental stages of Ostertagia ostertagi

1993 ◽  
Vol 67 (4) ◽  
pp. 271-278 ◽  
Author(s):  
H. de Cock ◽  
D. P. Knox ◽  
E. Claerebout ◽  
D. C. de Graaf
Keyword(s):  
Proteinase Inhibitor ◽  
Developmental Stages ◽  
Proteolytic Enzymes ◽  
Ostertagia Ostertagi ◽  
Protein Substrates ◽  
Stage Specificity ◽  
Specific Manner ◽  
Secretory Products

AbstractProteolytic enzymes present in extracts of third (L3) and fourth (L4) stage larvae and adults of the cattle nematode Ostertagia ostertagi were defined on the basis of pH optima and proteinase inhibitor sensitivity in spectrophotometric assays using azocasein and elastin-orcein as protein substrates. Evidence that different classes of proteinases are expressed in a stage specific manner was provided by the contrasting pH optima and inhibitor sensitivities shown by the enzymes in the different parasite stages. Stage specificity was confirmed by gelatin-substrate analysis. In addition, proteolytic activity was sought in the excretory/secretory products (ES) of the L4 following simple in vitro culture. Contrasting pH and inhibitor sensitivities as well as gelatin-substrate analysis showed that different proteinases were present in somatic L4 extracts and L4 ES products. The secreted proteinases may be useful targets for serodiagnosis or vaccination.

In-vitro evidence for the autoregulation of prolactin secretion at the level of the pituitary gland in the rat

1987 ◽  
Vol 115 (1) ◽  
pp. 13-18 ◽  
Author(s):  
A. M. Bentley ◽  
M. Wallis
Keyword(s):  
Monoamine Oxidase ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Prolactin Secretion ◽  
Anterior Pituitary Gland ◽  
Physiological Significance ◽  
Secretory Product ◽  
Secretory Products ◽  
Male Tissue

ABSTRACT The autoregulation of rat prolactin secretion at the level of the pituitary gland was investigated, using a static incubation system. The rate of prolactin secretion from the female anterior pituitary gland in vitro was found to be constant when the medium was changed at 20-min intervals. However, when the medium was left unchanged and secretory products were allowed to accumulate, prolactin secretion began to decline within 60 min. This effect was not observed with the male tissue, where the level of accumulated prolactin did not reach that at which the inhibition occurred using female tissue. The nature of the putative secretory product causing the inhibition of prolactin secretion was investigated. Exogenous bovine prolactin (1–4 mg/l) caused an inhibition of endogenous rat prolactin secretion. Inclusion of monoamine oxidase in unchanged medium, to prevent dopamine accumulation in the medium (a possible consequence of co-storage and cosecretion with prolactin granules), did not prevent the inhibition observed in the control incubation. We therefore conclude that in-vitro autoregulation of prolactin secretion can occur at the level of the pituitary gland, probably due to the accumulated prolactin having a feedback action on the lactotroph. This might be of physiological significance if localized concentrations of the hormone within the gland are high. J. Endocr. (1987) 115, 13–18

scholarly journals In Vivo Imaging-Driven Approaches to Study Virus Dissemination and Pathogenesis

2019 ◽  
Vol 6 (1) ◽  
pp. 501-524 ◽  
Author(s):  
Pradeep D. Uchil ◽  
Kelsey A. Haugh ◽  
Ruoxi Pi ◽  
Walther Mothes
Keyword(s):  
Cell Types ◽  
Whole Body ◽  
Whole Body Imaging ◽  
Causative Agents ◽  
Long Time ◽  
Approaches To Study ◽  
Living Organisms

Viruses are causative agents for many diseases and infect all living organisms on the planet. Development of effective therapies has relied on our ability to isolate and culture viruses in vitro, allowing mechanistic studies and strategic interventions. While this reductionist approach is necessary, testing the relevance of in vitro findings often takes a very long time. New developments in imaging technologies are transforming our experimental approach where viral pathogenesis can be studied in vivo at multiple spatial and temporal resolutions. Here, we outline a vision of a top-down approach using noninvasive whole-body imaging as a guide for in-depth characterization of key tissues, physiologically relevant cell types, and pathways of spread to elucidate mechanisms of virus spread and pathogenesis. Tool development toward imaging of infectious diseases is expected to transform clinical diagnosis and treatment.

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