cDNA cloning and recombinant expression of collagen-binding and complement inhibitor activity of Taenia solium paramyosin (AgB).
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Amino Acid Sequence↗
Biomedical subjects
A Landa
Publications and source records attributed to A Landa.
Alternative splicing of the Schistosoma mansoni gene encoding a homologue of epidermal growth factor receptor.
The complete coding DNA for a Schistosoma mansoni homologue of the epidermal growth factor receptor (SER) was characterized from cDNA clones obtained by homology to the tyrosine kinase domain of erbB. The DNA sequence predicts a 200-kDa translation product that contains a secretory leader, a cysteine-rich extracellular domain, a hydrophobic transmembrane sequence, and an intracellular tyrosine kinase domain. The SER transcript is present in cercariae and adult schistosomes. In addition to SER transcripts, schistosomes produce at least 3 variant transcripts encoding truncated SER products that include the secretory leader and a small portion of the extracellular domain followed by short sequences of unrelated, C-terminal amino acids. Based on these sequences, 2 of the variant mRNAs (class 2 and 5) appear to encode soluble, secreted proteins while one (class 4) encodes an SER variant protein with a hydrophobic C-terminus that may serve as a membrane anchor. Class 2 SER variant transcripts are present at levels comparable to SER transcripts in adult worms but are not detected in cercariae. Class 4 and 5 SER variant transcripts are also found within adult worms but at lower levels. Genomic cloning and characterization demonstrate that the variant SER transcripts arise through alternative splicing of the SER gene.
Amino Acid Sequence↗
Paramyosin is the Schistosoma mansoni (Trematoda) homologue of antigen B from Taenia solium (Cestoda).
Antigen B, a major antigen of the cestode parasite Taenia solium, has been purified and a portion of amino acid sequence obtained. Paramyosin of the trematode parasite Schistosoma mansoni, an immunogenic protein that has shown promise as a vaccine candidate, has several biochemical and immunological properties in common with antigen B. A full-length cDNA clone of S. mansoni paramyosin has been obtained and the predicted translation product contains a sequence that is highly homologous to the sequence obtained for antigen B. The predicted amino acid composition and isolectric point of paramyosin are nearly identical to those established for antigen B. Recombinant S. mansoni paramyosin, expressed in Escherichia coli as a fusion protein with beta-galactosidase, was recognized by antisera against T. solium antigen B. We conclude from these results that S. mansoni paramyosin and T. solium antigen B are homologous proteins. Since S. mansoni paramyosin is thought to be a muscle protein and T. solium antigen B a secreted glycoprotein with anti-complement activity, this conclusion raises some interesting questions regarding the role of this class of proteins in the host-parasite relationship.
Amino Acid Sequence↗
Cloning and sequencing of two actin genes from Taenia solium (Cestoda).
Genomic and cDNA actin clones were isolated from Taenia solium gene libraries. The actin genes are interrupted by intervening sequences. Protein coding regions of both genes predict the same amino acid sequence. cDNA sequence data indicate that at least one gene is expressed at the larval stage. Results from Northern and Western blots showed that T. solium expresses an actin transcript of about 1,400 bases and a protein of 45,000 Da.
Actins↗
The coexistence of Taenia solium cysticerci and the pig: role of the antigen B.
A review of data on the antigen B of Taenia solium (AgB) is presented. The biochemical, immunological and physiological properties of AgB are discussed in the context of the host-parasite relationship. It is proposed that AgB facilitates survival of cysticerci by impairing augmentation of the host inflammatory response through the inhibition of the classical pathway of the complement cascade. In this way, AgB not only allows evasion of the host immune attack but also decreases the host-parasite confrontation, facilitating their coexistence.
Animals↗
Melatonin blocks in vitro generation of prostaglandin by the uterus and hypothalamus.
The effects of melatonin on the motility (isometric tension developed and contractile frequency) of uterine horns isolated from ovariectomized rats as well as on the mechanical responsiveness to added oxytocin or prostaglandin F2 alpha (PGF2 alpha) were explored. The pineal indole (10(-6) M or higher) depressed significantly the spontaneous motility of the uterus and reduced the responses evoked by oxytocin but not those evoked by PGF2 alpha. Melatonin was also tested on the prostaglandin (PG) release into the suspending media from either uterine horns from spayed rats or bovine medial basal hypothalamic (MBH) explants. Melatonin (10(-3) M) diminished the output from the uterus or the MBH of both PGE and PGF-"like material". Similarities between the effects of melatonin and indomethacin as well as the possible physiological relevance of the present findings are discussed.
Animals↗
Is the spontaneous motility of isolated rat uterus controlled by prostaglandin E?
Variations in the spontaneous contractile activity during 6 hours following isolation of uterine horns from proestrus, metestrus and spayed rats, were explored. In estrus and metestrus preparations the contractions declined during 60 min and between 180--200 min a progressive spontaneous recovery (abolished by indomethacin) was observed up to 360 min. Uteri from proestrus and spayed animals exhibited a continuous depression without recovery during the whole experimental period. At 60 min, uterine horns from estrus animals (which showed a marked contractile decrement) released to the suspending medium significantly less prostaglandin E-like material than at 360 min, i.e. when contractions had almost completely recovered. No modification in the amount of prostaglandin F-like material was detected accompanying these spontaneous contractile variations. In the spayed group at 60 min of functioning (i.e. when the contractile impairment was significantly smaller than at a later time) the release of PGE was greater than at 360 min. These findings suggest a possible control of rat uterine contractions by PGE, rather than by PGF.
Animals↗
Spontaneous motility of isolated mesosalpinx-free isthmic and ampullar segments from human oviducts, and the influences of indomethacin and prostacyclin (PGI2).
The spontaneous contractile activity of isolated mesosalpinx-deprived isthmic and ampullar segments from estrogen dominated human oviducts and the influences of indomethacin, prostaglandin F2-alpha, (PGF2-alpha), E1 (PGE1), E2 (PGE2) and prostacyclin (PGI2) on their motility, were explored. Indomethacin enhanced significantly the Isometric Developed Tension (I.D.T.) of the isthmic but not the ampullar region. On the other hand, a single and identical concentration (10(-6) M) of PGE1 and PGI2 depressed the ampulla whereas PGE2 and PGF2-alpha enhanced its contractions. In the isthmus, PGE1, PGE2, and PGF2-alpha augmented whereas PGI2 diminished the I.D.T. Dose-response curves of PGI2 demonstrated a dose-dependent depression of I.D.T. and contractile frequency of both ampullar and isthmic regions. Furthermore, in the isthmus PGI2 resulted in a biphasic action on resting basal tone (depressing at low and augmenting at high concentrations), whereas in the ampulla only a progressive dose-dependent decline, was observed. The results suggest that a prostaglandin with inhibitory capacity, presumably PGI2, may be synthesized by the human isthmus and play some role in the reduced spontaneous activity observed under estrogenic dominance.
Epoprostenol↗
Drug-induced motility of sow (Sus scrofa) graafian follicles isolated during pre and post-ovulatory periods of the sex cycle.
The spontaneous as well as the drug-induced motility of sow graafian follicles during the early-preovulatory (E-preovulatory), late-preovulatory (L-preovulatory) and post-ovulatory stages of the sex cycle, were studied. Spontaneous motility was present only in 30.9% of the E-preovulatory and in 18.1% of the L-preovulatory, whereas none of the post-ovulatory follicles showed spontaneous contractions. All the quiescent preparations reacted, with a comparable enhancement of tension, to the addition of acetylcholine. On the other hand, norepinephrine (NE) elicited upon L-preovulatory and post-ovulatory follicles a significantly greater contractile response than over E-preovulatory preparations. The presence of MJ-1999 augmented clearly the positive influence of NE upon the contractile tension of E-preovulatory follicles, whereas cocaine, U-0521 or indomethacin failed to alter the reactivity towards NE in all the groups. The inotropic influence of prostaglandins were also explored over quiescent follicles. PGE1 diminished the basal tension of the three types of follicles, whereas PGF2-alpha produced the opposite effect. On the other hand, PGE2 enhanced the tonic tension of E and L-preovulatory preparations and reduced the basal tone of post-ovulatory follicles. The role of the spontaneous motility of smooth muscle fibers surrounding graafian follicles, as well as the effects of several autacoids and neurotransmitters prior and following ovulation are discussed in relation to their possible relevance for the ovulatory process.
Acetylcholine↗
[Rhabdomyosarcoma. Presentation of a clinical case].
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Child↗