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N M Delgado

Publications and source records attributed to N M Delgado.

At least 19 recordsLinked to original sources
PubMed1992

RNA metabolism during the sexual differentiation of rat hypothalamus.

Modifications in the basal molecular biology parameters (total concentrations of RNA, DNA, proteins, rRNA, tRNa, free and polysomal bound poly-A+ mRNA) have been determined daily in the growing hypothalamus of male and female rats from day 1 to day 8 after birth. Changes observed in the parameters studied in this work occurred mainly in the first 48 h after birth. In males tRNA and free mRNA (f-mRNA) contents decreased from day 1 to day 2 and then their concentrations remained more or less constant. Total mRNA significantly decreased from day 1 to day 3 and showed a further significant decrease from day 6 to day 8. Polysomal bound-mRNA (b-mRNA) decreased from day 1 to day 3, then increased to day 6, and finally decreased once more from day 6 to day 8. The b-mRNA/f-mRNA, mRNA/rRNA and mRNA/total RNA ratios showed a bimodal behavior with a first peak on day 2, and a second, smaller peak, on days 6-7. The changes observed in the females on the first 2-3 days of life were the inverse of those observed in the males, most of the parameters studied showed a sharp increase from day 1 to day 2 or to day 3 and then a drastic decrease. The only exception to this behavior was the b-mRNA/f-mRNA ratio which showed a small decrease from day 1 to day 2, followed by a continuous increase from day 2 to day 8. b-mRNA concentrations, after the sharp decrease from day 2 to day 3 of life, increased from day 3 to day 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Differences in lipoprotein composition between heads and tails of human sperm: an infrared spectroscopy study.

Human spermatozoa and their fractions (heads and tails) have been studied by infrared spectroscopy. Protein conformation in isolated human spermatozoa heads, although predominantly of the alpha helix or random coil type, has a significant proportion of antiparallel B structure. Spectra of isolated spermatozoa tails show that proteins exist in this fraction preponderantly in pleated-sheet conformation (parallel and antiparallel). The quantity and type of lipids seem to be drastically different between heads and tails of spermatozoa. Head lipids are scarce and difficult to extract, and they are apparently tightly bound to proteins, highly unsaturated, and rich in free hydroxyl and carboxyl groups. Tail lipids are more abundant and more easily extractable. Head phospholipids are probably phosphatidylcholine, cephalins, and inositols, and tail phospholipids are preponderantly plasmalogen-type lecithins and sphingomyelins. The presence of specific infrared bands points to the existence in tails of important amounts of sulfur compounds, probably sulfolipids or sulfoglycolipids.

Humans↗
PubMed1990

Glycosaminoglycan-sulfate as plasma membrane component of pig spermatozoa.

The effect of specific glycosaminoglycan-hydrolyzing enzymes on the ruthenium red staining of pig spermatozoa was studied. Washed spermatozoa were incubated at 35 degrees C in buffer or with neuraminidase 0.5 units/ml, heparinase 0.2 mg/ml, or chondroitinase ABC 2.0 units/ml. After incubation sperm cells were washed, stained with ruthenium red and studied under the electron microscope. Anionic sites in the surface of untreated spermatozoa follow regularly the plasma membrane, but present are numerous processes constituting what has been defined as the glycocalyx. Neuraminidase did not affect the distribution of ruthenium red on the surface of the spermatozoa, but eliminated almost completely the processes of the glycocalyx. Heparinase caused loss of the ruthenium red-stained sites on the membrane surface of pig spermatozoa with less influence on the dense processes of the glycocalyx. A similar loss of ruthenium red-stained sites was observed with nitrous acid treatment. A striking effect of treatment with chondroitinase ABC was the production of a typical acrosome reaction.

Animals↗
PubMed1989

Heparin and glutathione: physiological decondensing agents of human sperm nuclei.

It has been proposed that reduced glutathione (GSH) or other thiol reagents may participate in the basic mechanism by which sperm-decondensing activity is accomplished. However, in vitro, these reagents seem to be inactive and require the presence of other chemicals, usually detergents. Heparin binds specifically to the sperm membrane and provokes the decondensation of human sperm and the activation of DNA transcription and synthesis. However, the concentrations at which these effects occur seem to be higher than those expected under physiological conditions. In the present study, thiol reagents at 10 mM concentration, either alone or combined, were completely ineffective in inducing any significant nuclear decondensation after prolonged exposures (24 hr) of incubation. Heparin, 153.8 microM, was capable of inducing only a small increase in nuclear swelling. However, GSH at concentrations as low as 0.1 mM in combination with heparin induces decondensation of human sperm nuclei in vitro. When GSH concentration was kept constant at 5 mM, nuclear decondensation was induced with heparin at concentrations as low as 11.6 microM, and a maximal decondensation (90%) was obtained with only 21.6 microM of heparin. The latter is more than ten times less than the minimal active concentration of heparin used alone.

Cell Nucleus↗
PubMed1988

Binding of chemotactic peptide to the outer surface and to whole human spermatozoa with different affinity states.

Binding of N-formyl-methionyl-L-leucyl-[3H]phenylalanine (fML[3H]Ph) to human ejaculated spermatozoa and to its isolated plasma membrane was studied. Our data confirm the presence of specific receptors for f-MLPh in the human spermatozoa and suggest that whole spermatozoa receptors exist in two affinity states, one high-affinity, low-capacity specific receptor (Kd = 12.3 +/- 0.5 nM, n = 22,285 +/- 65,008 binding sites per sperm cell) and a second one (Kd = 700 +/- 47 nM) that is not saturable, indicating a low-affinity, high-capacity nonspecific site. In contrast, sperm membrane showed only one class of binding site (Kd = 6.4 +/- 0.12 nM), which was statistically different from that of the high-affinity binding site of intact spermatozoa. To explain this difference we discuss the possibility that first, the two binding affinities represent two interconvertible states of a single receptor population, which, depending on the metabolic activity of spermatozoa, may change its physicochemical properties; or second, they reflect two different processes, binding and/or transport into the spermatozoa.

Cell Membrane↗
PubMed1988

Size-uniform heparin fragments as nuclear decondensation and acrosome reaction inducers in human spermatozoa.

Using size- uniform mixtures of di-, tetra-, octa- and decasaccharides obtained from the depolymerization of heparin with heparinase, we have studied the activity that these low molecular weight heparin fragments may have on the acrosome reaction and sperm nuclei decondensation processess. Swelling of human spermatozoa nuclei was stimulated by heparin and their fragments and was dependent on the incubation time and directly correlated with the size of the fragment tested. Disaccharides were unable to increase the number of swollen nuclei. At short times (2-8 hrs) decasaccharides were the most active substances tested, including heparin. Only heparin and the tetra- and decasaccharides showed a significant increase in the number of acrosome-reacted spermatozoa, both fragments were more active than heparin at 2 hour incubation. Hexa- and octasaccharides induced a slight increase in the number of acrosome reacted spermatozoa and disaccharides were ineffective. The presence in animal systems of oligosaccharides derived from macromolecules and having specific biochemical properties, remembers the recent discovery of to those mediated by oligosaccharins in plants may exist in animals.

Acrosome↗
PubMed1988

Structure of human sperm chromatin: a study on the accessibility of DNA to macromolecules.

The structure of human sperm chromatin compared with somatic chromatin (liver) was studied by titration of the exposed DNA-phosphate groups with poly-1-lysine (3000 and 28,100 MW) and by their susceptibility to the hydrolytic action of micrococcal nuclease and DNase I. With both sizes of polylysine used, the binding values were significantly lower for sperm chromatin (0.31 +/- 0.05) than for liver chromatin (0.52 +/- 0.05), indicating the presence of about 30% and 52% of free phosphate groups, respectively. Interaction with liver chromatin left no polylysine molecules partially unbound ("wastage") even when 28,100 MW polylysine was used; on the contrary, sperm chromatin showed 26% of "wasted" polylysine even when the smaller polymer was used, indicating that in sperm chromatin the accessible DNA zones are usually no longer than 42 A, that is, 12 base pair. Sperm chromatin was notably more susceptible to both micrococcal nuclease and DNase I action than liver chromatin. However, in the presence of saturating concentrations of polylysine they were similarly protected. Micrococcal nuclease and DNase I hydrolysis products of sperm fractions when submitted to electrophoresis produced a polydisperse smearing pattern along the gel that was difficult to correlate with the presence of nucleosomal structure.

Chromatin↗
PubMed1987

Increased acrosome-reaction inducing activity of glycosaminoglycans by partial hydrolysis.

The possibility that partial hydrolysis of glycosaminoglycan-sulfates (GAGs) such as occurs during the last phases of follicular maturation could play some role in the activity of follicular fluid as an inducer of the acrosome reaction was explored. Hydrolysis of follicular fluid GAGs (ff-GAGs) for 30 min with low-pH HNO2 substantially increased (more than 3 times) its capacity to induce the acrosome reaction. This increase was significantly reduced when the time of hydrolysis was either shorter (10 min) or longer (60 min). Partial hydrolysis of spermatozoa GAGs by direct incubation of sperm cells with chondroitinase ABC was also capable of inducing the acrosome reaction.

Acrosome↗
PubMed1986

Taurine content and amino acid composition of human acrosome.

The presence and concentration of taurine was determined by amino acid analysis in human spermatozoa acrosomes isolated by the method of Srivastava. Taurine is one of the four amino acids whose concentration is higher in the acrosomal extracts, being only lower than histidine, methionine and lysine. It is worth mentioning that these four amino acids constituted 50% the free amino acid concentration in this organelle. The role that this high concentration of taurine, and also the presence of considerable amounts of methyl histidine may have in the functioning of the acrosome, is discussed.

Acrosome↗
PubMed1978

Metabolic changes induced in human spermatozoa by subagglutinating concentrations of specific antibodies.

The effects on sperm metabolism of subagglutinating concentrations of infertile female sera, containing antisperm antibody, were studied. Sera were selected by their differential agglutinating or immobilizing properties and by high titers of activity. Only the immobilizing antibodies were able to decrease sperm viability. Basal and succinate depending oxygen uptake, thus as progressive motility was decreased by sera producing mixed agglutination and more drastically by that producing immobilization independent of the presence of complement. The sera with head-to-head agglutination properties induced an increase in the above mentioned physiologic parameters. Tip of tail-to-tip of tail agglutinating sera having no effect on oxygen uptake were able to induce a significant increase in progressive motility. Conversion of 14C-Glucose to 14CO2 was decreased by sera that induced tip of tail-to-tip of tail agglutination and complement-independent immobilization. The sera which induced head-to=head agglutination and immobilization on the presence of complement, were without effect. None of the tested sera showed any acitivity over the conversion of 14C-Glucose to 14C-Lactate.

Antibodies↗
PubMed1977

Cyclic changes in salivary activity of N-acetyl-beta-d-glucosaminidase; a possible efficient indicator for predicting ovulation and pregnancy.

Salivary activity of N-acetyl-beta-D-glucosaminidase showed a characteristic pattern of changes during the normal menstrual cycle with a distinct peak on Day 13, 14, or 15 before the next menstruation. This peak of enzyme activity occurred withing one day of the nadir of basal body temperature and was absent in women with spontaneous or iatrogenic anovulatory cycles. These results are stongly suggestive that the salivary determination of this activity may be convenient indicatior for determining the day of ovulation.

Body Temperature↗
PubMed1977

Osmolality and conductance of normal and abnormal human seminal plasma.

The possible correlation between two important general properties of seminal plasma, osmolality and conductance, and the presence of some pathological conditions of human semen, asthenospermia and oligoasthenospermia, have been studied. Osmolality was measured under carefully controlled conditions by the freezing point depression method and conductance with a Wheatstone bridge. In addition, volume, by an isotopic dilution method, and pH were also determined. Osmolality of normal human seminal plasma (366 +/- 16 mOsm/Kg) was found to be higher than the osmolality of human blood serum. Abnormal seminal plasma showed a still higher value (428 +/- 38 and 457 +/- 49 mOsm/Kg respectively for astheno- and oligoasthenospermic subjects). Incubation of normal seminal plasma for 24 hours at room temperature produced a significant increase in osmolality (from 366 +/- 16 to 430 +/- 31 mOsm/Kg) while pathological seminal plasma failed to show any modification. Osmolality and conductance values were found to be correlated with semen ejaculated volume in normal subjects. No difference in mean conductance value was found between normal and asthenospermic individuals (10.4 +/- 1.2 against 9.9 +/- 1.0 mhos X 10(-3) respectively). Oligoasthenospermics showed, on the contrary, a significantly higher conductance (12.4 +/- 1.6 mhos X 10(-3)).

Adult↗
PubMed1976

Changes in the protein conformation of human spermatozoal membranes after treatment with cyclic adenosine 3':5'-monophosphate and human follicular fluid.

Infrared spectra in the amide I and amide II regions of acrosomal membranes isolated from ejaculated human spermatozoa indicate the presence of a high proportion of the constitutive proteins in the most stable protein configuration, the antiparallel beta-conformation. Since the infrared spectra obtained with the membranes suspended in D2O or after extraction of the lipid components do not show any significant change, it can be postulated that the antiparallel pleated sheet conformation of human spermatozoal membrane proteins is independent of the hydrated state and of the lipid constitution of the membrane.

Acrosome↗
PubMedDate not supplied

Male pronuclei formation release of phosphorylation of histone H-3 during decondensation of human sperm nuclei activated in vitro by heparin.

The release and phosphorylation/dephosphorylation mechanisms of human spermatozoa histone during nuclei in vitro decondensation by heparin was studied. Washed sperm cells were incubated in the presence of 32P and in the absence or presence of heparin. The results showed an increase in the incorporation of 32P of 20 times greater in the presence of heparin than in the absence of heparin (the control sample). In some cases the incorporation of 32P into histones was confirmed by its isolation. To validate these results a phosphorylation kinetic of isolated sperm histone, used as a substrate, was performed. The amount of 32P was not a linear function of time, and maximal phosphorylation was reached in 60 min. A measurement of 32P incorporated as a function of the amount of histone, shows a linear relationship of up to 50 micrograms of protein, with a rapid saturation thereafter with the incorporation of 220 nm and with a KD = 442 x 10(-6) mol/L. 32P incorporation, independent of exogenous cAMP, was related to alkaline pH but was totally dependent on temperature--with a maximum of 37 degrees C. The only histone released was histone H-3. Phosphorylation/dephosphorylation is involved during male pronuclei formation.

3',5'-Cyclic-AMP Phosphodiesterases↗