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Biomedical subjects

F D Rumjanek

Publications and source records attributed to F D Rumjanek.

At least 37 records · Page 2Linked to original sources
PubMed1989

DNA binding proteins of Schistosoma mansoni recognizing a hexanucleotide motif occurring in genes regulated by steroids.

1. Schistosome proteins interacting with a gene (F-10), which is only expressed in adult females, were investigated. 2. These were also tested using a synthetic oligonucleotide of 20 bp bearing a defined sequence derived from the F-10 gene and containing a hexanucleotide motif, TGTCCT, occurring in genes responsive to steroids. 3. Schistosome proteins (male and female) bound to the F-10 DNA, but only the male proteins bound to the synthetic oligonucleotide with high affinity. 4. The other preparations each produced different binding patterns, although this seemed to lack specificity. 5. These results indicated that the F-10 gene binds different proteins along its structure and suggested that proteins present in the male schistosomes may regulate its expression.

Animals↗
PubMed1989

Protein characterization of sexually mature and immature forms of Schistosoma mansoni.

1. Protein composition of different stages of Schistosoma mansoni was compared using specific antisera, 2D polyacrylamide gel electrophoresis and 14-C-leucine incorporation into proteins. 2. Major qualitative differences were detected when an anti-membrane antiserum was used. 3. 2D gel electrophoresis showed that the protein composition varied when mature and immature females were compared, whereas no differences were noted when mature and immature male worms were compared. 4. Experiments measuring protein synthesis by the different schistosome stages confirmed that upon maturation, only the female schistosomes displayed qualitative differences. 5. The protein pattern of the male schistosomes did not vary significantly as a function of development.

Animals↗
PubMed1989

Serological response of patients with leprosy to a 28- to 30-kilodalton protein doublet from early cultures of Mycobacterium bovis BCG.

Analysis by Western immunoblotting of Mycobacterium bovis BCG short-term culture filtrates with a pool of serum samples from lepromatous leprosy patients revealed an immunodominant protein doublet with apparent molecular masses of 28 and 30 kilodaltons (kDa). The humoral response to these antigens was also investigated by using individual serum samples from patients representative of the whole spectrum of leprosy and from tuberculosis patients, as well as from contacts of leprosy patients and control groups. The protein doublet was recognized by 92% of the sera from patients with lepromatous leprosy (51 of 56), whereas essentially negative results were obtained with sera from the other groups. Similar immunodominant bands were also detected by Western blotting analysis of sonic extracts of seven other slow- and fast-growing mycobacterial species, suggesting a broad distribution of these antigens within the genus. Analysis of the purified doublet by Western blotting after two-dimensional gel electrophoresis fractionation showed that the 28- and 30-kDa doublet consisted of at least five different components with pls from 5.2 to 5.7 and molecular masses from 28 to 31 kDa. These results indicate that the protein doublet could be used as a potential marker in the diagnosis of lepromatous leprosy.

Antibodies, Bacterial↗
PubMed1989

Regulation of gene expression in the Schistosoma mansoni female.

The maturation of females of S. mansoni is a process which depends on the presence of male parasites. Preliminary results indicated that the males may secret hormones, possibly steroid or steroid-like compounds, which regulate the expression of genes directly connected to events pertaining to oogenesis. Because the eggs are important agents in the pathology of schistosomiasis, it is of interest to elucidate the biochemical events associated to this developmental stage. The present work describes the efforts to characterize proteins which regulate the expression of a gene encoding a major protein precursor of egg shells and which is only transcribed by adult females. It is hoped that the receptor for the male hormone will be detected among these regulatory proteins.

Animals↗
PubMed1988

Evidence for the occurrence of LDL receptors in extracts of schistosomula of Schistosoma mansoni.

Schistosomula of Schistosoma mansoni were shown to contain proteins on their surface membranes which bind iodinated human low density lipoproteins (125I-LDL). Treatment of the parasites with trypsin decreased the binding in comparison with untreated controls. Membrane-bound, acetone-insoluble proteins were extracted from the schistosomula with Triton X-100 and the extract in liposome form was incubated with 125I-LDL at room temperature. After incubation a complex was formed between the proteins present in the extract and 125I-LDL, as shown by a filter binding assay. 125I-LDL binding to filters was proportional to the amount of protein in the extract; it was inhibited by unlabelled LDL and VLDL and by EDTA. Binding of 125I-LDL to proteins present in the liposome suspension containing the Triton X-100 extract followed saturation kinetics, indicating the occurrence of receptors for lipoproteins in the extract.

Animals↗
PubMed1987

Schistosoma mansoni: human serum and release of proteins from schistosomula.

Radioiodinated surface proteins of schistosomula of Schistosoma mansoni, including those involved in low density lipoprotein binding, are released into a defined culture medium at 37 C at slower rates than proteins from schistosomula incubated in a serum-containing medium. When schistosomula were incubated at 4 C, a higher degree of reassociation of the same proteins into the parasites was detected. Purified human low density lipoproteins and a fraction containing very low density lipoprotein plus chylomicrons were also able to promote the release of iodinated proteins from the parasites. These observations suggest that serum may play a role in accelerating the turnover of membrane components in schistosomula.

Animals↗
PubMed1986

Transfer of [14C] cholesterol and its metabolites between adult male and female worms of Schistosoma mansoni.

Adult male and female worms of Schistosoma mansoni are able to incorporate [14C]cholesterol and convert it into several metabolites. Schistosomula on the other hand cannot convert the incorporated cholesterol. Male worms are able to transfer the [14C]cholesterol and labelled metabolites to female worms but labelled female worms can transfer cholesterol but are unable to transfer the conversion products of cholesterol to male worms. Uptake by female worms of labelled products shed by male worms seems to occur more efficiently in the presence of serum than in its absence.

Animals↗
PubMed1985

The interaction of human serum with the surface membrane of schistosomula of Schistosoma mansoni.

After contact with human serum, a series of proteins become exposed on the surface membranes of schistosomula of Schistosoma mansoni as revealed by radioiodination of the intact parasites. Among the proteins, a doublet (Mr 45 000) is particularly prominent. These doublet proteins, which are believed to be parasite-derived, become apparent after a very short time of incubation with human serum (10 min or less) and are expressed on the surface membranes after contact with a high molecular weight component of human serum (Mr greater than 80 000). Pretreatment of the parasites with 1.25 mM colchicine or fixation with 2% glutaraldehyde does not prevent the serum-induced expression of the doublet proteins. Extraction of the parasites with chloroform:methanol 2:1 (v/v), however, blocks the human serum effect. Affinity chromatography using immobilized low density lipoproteins (LDL) from human serum shows a tight binding between the 125I-labelled 45 kDa doublet to the LDL. The possible role of the 45 kDa doublet as a receptor for LDL is discussed.

Animals↗
PubMed1983

The occurrence of proteolipid antigens in Schistosoma mansoni.

Adult Schistosoma mansoni were shown to synthesize a peptide containing lipid against which an antiserum could be raised in rabbits. The proteolipid purified by silicic acid chromatography was soluble in chloroform/methanol mixtures, it was very hydrophobic and contained fatty acids in its molecule, as well as other unidentified neutral lipids.

Amino Acids↗
PubMed1983

Serum-induced expression of a surface protein in schistosomula of Schistosoma mansoni: a possible receptor for lipid uptake.

When freshly transformed schistosomula of Schistosoma mansoni are incubated with human serum, a protein doublet (molecular weight approximately 45 kDa) is expressed on the surfaces of the parasites; parasites incubated in defined media fail to express the doublet proteins. A 30 min exposure to serum is sufficient to induce the expression of the doublet, and even when the parasites are separated from the serum by a dialysis membrane, the doublet is still expressed. The doublet proteins are shown to be synthesized by cercariae, but not by schistosomula; they can be extracted using detergents and immunoprecipitated by specific antisera. Following expression of the doublet, purified low density lipoproteins from human serum interact with the schistosomula, become adsorbed onto their surface membranes and are possibly internalized and degraded.

Animals↗
PubMed1981

Glycosyl transferase activities are associated with the surface membrane in adult Schistosoma mansoni.

Incubation of live adult Schistosoma mansoni in a variety of media released tegumental material containing membrane bound alkaline phosphatase, mannosyl transferase and galactosyl transferase activities. Centrifugation of the tegumental material released by incubation of worms in phosphate-buffered saline in sucrose density gradients yielded a pellet and four fractions, two of which consisted mainly of surface membranes. The distribution of the enzymes in the gradient, espeically in the two surface membrane-containing subfractions was similar. Application of the "digitonin shift" technique showed that the membranes containing the enzyme reactivities were moved to an equal extent into a denser part of the sucrose gradient. Thus the enzymes are located on the same or similar cholesterol-containing membranes. It is concluded that the transferases, like the alkaline phosphatases, are located in the surface membranes of S. mansoni and the consequences of this location for the host-parasite interaction are discussed.

Alkaline Phosphatase↗
PubMed1981

Schistosoma mansoni: modulation of schistosomular lipid composition by serum.

Human serum and foetal calf serum have been compared in terms of their ability to modify the biochemical and immunological properties of the schistosomular surface. Artificially transformed schistosomula were incubated in the presence of serum for 24 h and then radioiodinated using the chloramine T method. With this method only lipids are labelled. Foetal calf serum produces a net loss of lipids from the schistosomula, particularly of mono- and diglycerides. Human serum however, promotes not only a loss of mono- and diglycerides, but also a substantial uptake of cholesterol and triglycerides. Schistosomula recovered from the lungs of mice could also be labelled and contained besides triglycerides, an increased amount of cholesterol esters. The modulation of surface lipids in worms cultured with human serum correlates with the observation that such schistosomula develop significantly greater protection against eosinophil-mediated cytotoxicity in vitro than do individuals incubated with foetal calf serum. On the other hand, schistosomula cultured in the presence of either human serum or foetal calf serum develop the same degree of protection against complement-dependent lethal antibody; this result indicates that resistance against complement-mediated damage may be independent of the uptake of cholesterol and/or triglycerides, and might involve only limited alterations in the surface configuration of the schistosomulum.

Animals↗
PubMed1980

The incorporation and utilization of radiolabelled lipids by adult Schistosoma mansoni in vitro.

Live adult Schistosoma mansoni, maintained in vitro were able to absorb and utilize radiolabelled arachidonic acid, linolenic acid, 3-sn-phosphatidylcholine, tripalmitylglycerol and cholesterol in the culture medium. Differential centrifugation demonstrated that all these lipids were incorporated into the parasite's various membrane structures. Analysis by thin-layer chromatography of the labelled compounds which resulted from incubation with the labelled lipids revealed that arachidonic acid, linolenic acid and fatty acids of tripalmitylglycerol and 3-sn-phosphatidylcholine were present largely as triacylglycerol with smaller amounts of labelled diacylglycerol, phospholipids and fatty acids. The labelled polar head group of 3-sn-phosphatidylcholine was cleaved from the molecule during incorporation, which suggested that hydrolysis of complex lipids is an integral part of the absorption mechanism. Cholesterol was not apparently altered during incorporation or further metabolized. It was also observed that arachidonic acid was incorporated more readily than the other lipids, however, no prostaglandin biosynthesis was detected.

Absorption↗
PubMed1978

Mannosyl transferase activity in homogenates of adult Schistosoma mansoni.

Homogenates of adult Schistosoma mansoni contain enzymes which are capable of transferring [14C]mannose from GDP[U-14C]mannose to a lipid acceptor which migrates as a single peak on a silica gel thin-layer plate. This lipid may belong to the class of polyprenol monophosphates which are intermediate elements in the glycosylation of nascent proteins. The schistosome mannosyl transferase activity is associated with membranous particles and is dependent on the presence of Mn2+. However, other divalent metals such as Mg2+ or Ca2+ can, in decreasing order of efficiency, replace Mn2+. When UDP[U-14C]glucose was incubated with the homogenates in the same conditions, relatively little label was transferred to the lipid acceptor. Live worms incubated in a medium containing GDP[U-14C]mannose seem to incorporate the label preferentially on the tegument and on adjacent subtegumental structures. By adding foetal calf serum to the medium, incorporation of the label can be stimulated.

Animals↗