N-(triphenylmethylsulfanyl)phthalimide.

The title compound, C27H19NO2S, contains chains of fused R(2)(2) (19) rings formed by intermolecular C-H...

Role of the sperm proteasome during fertilization and gamete interaction in the mouse.

In this work, we have investigated the role of the sperm proteasome during in vitro fertilization (IVF) and gamete interaction in the mouse. Proteasome activity was measured in extract and intact sperm using a specific substrate. In addition, sperm were treated with specific proteasome inhibitors and evaluated during IVF, binding to the zona pellucida, and progesterone- and zona pellucida-induced acrosome reactions.

Proteasomal activity in mammalian spermatozoa.

The proteasome is a multicatalytic cellular complex, which possess three different enzymatic activities, trypsin-like, chymotrypsin-like, and peptidylglutamyl peptidase. Its function is to remove abnormal or aged proteins. Recently, it has been suggested the participation of the sperm proteasome during mammalian fertilization.

Comparison of two techniques to evaluate the acrosomal status of zona pellucida bound sperm in humans.

In this work, we have compared two procedures that evaluate the acrosomal status of human sperm bound to the human zona pellucida. Motile sperm, selected by a Percoll gradient, were capacitated by incubation at 37 degrees C, 5% CO2, for 4.5 h, at 20 x 10(6) cells ml(-1).

Extracellular localization of proteasomes in human sperm.

The proteasome, a multienzymatic protease complex is present in human sperm. Here we present evidence indicating that the proteasome has an extracellular localization, on the plasma membrane of the sperm head. Motile sperm (>90%) in PBS were incubated with the proteasome inhibitors clasto-lactacystin beta-lactone or epoxomicin.

A novel protein phosphatase 2A (PP2A) is involved in the transformation of human protozoan parasite Trypanosoma cruzi.

Here we provide evidence for a critical role of PP2As (protein phosphatase 2As) in the transformation of Trypanosoma cruzi. In axenic medium at pH 5.0, trypomastigotes rapidly transform into amastigotes, a process blocked by okadaic acid, a potent PP2A inhibitor, at concentrations as low as 0.

Effect of azorellanone, a diterpene from Azorella yareta Hauman, on human sperm physiology.

Previous studies have shown that cyclic terpenes extracted from plants decrease sperm motility and concentration in rats. In this work, we studied the effect 13-alpha-hydroxy-7-oxoazorellano (azorellanone), a cyclic diterpene extracted from Azorella yareta Hauman, on in vitro human sperm physiology. Sperm aliquots, capacitated for 4.

Participation of the sperm proteasome in human fertilization.

Background: Fertilization in mammals comprises the sequential interactions of the sperm with the cumulus oophorus, zona pellucida, and oocyte plasma membrane. Here we investigate proteasome activity in human sperm and its possible involvement during the fertilization process.

Methods: Proteasome activity was measured in intact sperm and in sperm extracts using the fluorogenic substrate Suc-Leu-Leu-Val-Tyr-AMC, in the presence or absence of the specific proteasome inhibitor, clasto-lactacystin beta-lactone.

Sperm binding to the human zona pellucida and calcium influx in response to GnRH and progesterone.

In this study the effect of the sequential exposure of spermatozoa to progesterone and gonadotrophin-releasing hormone (GnRH) upon zona binding and the intracellular free Ca2+ concentration was evaluated. Sperm aliquots were treated as follows: (a) 0.7 micro mol l(-1) progesterone or 0.

Inhibition of in vivo and in vitro fertilization in rodents by gonadotropin-releasing hormone antagonists.

We have examined the effect of two GnRH antagonists, Ac-D-Nal(1)-Cl-D-Phe(2)-3-Pyr-D-Ala(3)-Arg(5)-D-Glu(AA)(6)-GnRH (Nal-Glu) and Ac(3,4)-dehydro-Pro(1),-p-fluoro-D-Phe(2),D-Trp(3,6)-GnRH (4pF), on in vivo and in vitro fertilization in rodents. Female rats were treated in the afternoon of proestrus with 2 micro l of Nal-Glu or 4pF (0.5 and 5 mM) injected directly into one oviductal horn (experimental); saline was injected into the contralateral horn (control).

Drowning-out crystallisation of sodium sulphate using aqueous two-phase systems.

A novel method to obtain crystals of pure, anhydrous salt, using aqueous two-phase systems was studied. A concentrated salt solution is mixed with polyethylene glycol (PEG), upon which three phases are formed: salt crystals, a PEG-rich liquid and a salt-rich liquid. After removal of the solid salt, a two-phase system is obtained.

Gonadotropin-releasing hormone-stimulated sperm binding to the human zona is mediated by a calcium influx.

The mechanism by which GnRH increases sperm-zona pellucida binding in humans was investigated in this study. We tested whether GnRH increases sperm-zona binding in Ca(2+)-free medium and in the presence of Ca(2+) channel antagonists. We also examined the GnRH effect on the intracellular free Ca(2+) concentration ([Ca(2+)](i)).

Proteasome-dependent cyst formation and stage-specific ubiquitin mRNA accumulation in Entamoeba invadens.

Proteases play an important role in the pathogenic mechanisms and differentiation events of protozoan parasites; the proteasome/ubiquitin system is essential for maintaining the differentiation state of many cell types. A single input of the specific inhibitor of proteasomes, lactacystin, prevented encystation of the protozoan parasite Entameoba invadens, whereas a cysteine protease inhibitor, E64, only delayed encystation. The ameba target of lactacystin was purified and it displayed the features typical of eukaryotic 20S proteasome complexes.

Gonadotrophin-releasing hormone antagonists inhibit sperm binding to the human zona pellucida.

Previous work from our laboratory indicated that gonadotrophin-releasing hormone (GnRH) increases human sperm-zona pellucida binding. Here we present evidence that GnRH antagonists inhibit sperm-zona pellucida binding in humans. Motile spermatozoa (10(7) cells/ml) were incubated in modified Tyrode's medium at 37 degrees C, in 5% CO(2) in air.

Sperm penetration through the human zona pellucida as a predictor of in vitro fertilization.

The aim of this study was to determine the predictive value of sperm penetration into the perivitelline space of human cadaveric oocytes on in vitro fertilization outcome. Forty-two patients with tubal infertility undergoing ovarian stimulation with gonadotropin for in vitro fertilization and embryo transfer participated in the study. The number of spermatozoa bound to the human zona pellucida, the percentage of cadaveric oocytes with one or more spermatozoa in the perivitelline space, and the in vitro fertilization outcome were evaluated.

Gonadotropin-releasing hormone increases ability of the spermatozoa to bind to the human zona pellucida.

Sperm-zona pellucida binding, a crucial step in the process of fertilization, takes place in vivo in the upper portion of the fallopian tube. The presence of GnRH-like peptides in the female and the male genital tract has been described. In this work, the effect of GnRH and related peptides upon sperm-zona pellucida binding ability was studied.

Biochemical, immunological, and biological characterization of Trypanosoma cruzi populations of the Andean north of Chile.

Twenty-one Trypanosoma cruzi stocks isolated from Triatoma infestans and humans of the Chilean Andean highlands were studied at the genotypic level by schizodeme and molecular karyotype analyses, which allowed a clear distinction of the parasites from those hosts. A phenotypical characterization was performed by proteolytic activity after electrophoretic fractionation without discrimination among the stocks. Metacyclic trypomastigotes obtained in vitro proved to be infective to Swiss mice and the study of immune response and biological behavior was assessed.