Formation of an r8-Dominant Si Material.

The rhombohedral phase of Si (r8-Si), a promising semiconducting material, is formed by indentation together with the body-centered cubic phase (bc8-Si). Using a novel sample preparation method, x-ray diffraction is used to determine the relative volume of these phases in indented Si and allow observation of a distorted unit cell along the direction of indentation loading. Theoretical calculations together with these observations suggest the indent contains an intrinsic compression of ∼4 GPa that stabilizes the r8 phase.

Lattice reduction using a Euclidean algorithm.

The need to reduce a periodic structure given in terms of a large supercell and associated lattice generators arises frequently in different fields of application of crystallography, in particular in the ab initio theoretical modelling of materials at the atomic scale. This paper considers the reduction of crystals and addresses the reduction associated with the existence of a commensurate translation that leaves the crystal invariant, providing a practical scheme for it. The reduction procedure hinges on a convenient integer factorization of the full period of the cycle (or grid) generated by the repeated applications of the invariant translation, and its iterative reduction into sub-cycles, each of which corresponds to a factor in the decomposition of the period. This is done in successive steps, each time solving a Diophantine linear equation by means of a Euclidean reduction algorithm in order to provide the generators of the reduced lattice.

Hipotiroidismo subclínico en mujeres infértiles / Subclinical Hypothyroidism in Infertile Women

Objetivo: Comparar la frecuencia de hipotiroidismo subclínico (HSC) entre mujeres con infertilidad primaria (IP) y secundaria (IS) asistidas en la consulta de ginecología de la Maternidad “Dr. Armando Castillo Plaza”, en Maracaibo, estado Zulia. Métodos: Investigación comparativa y aplicada, con diseño de tipo no experimental, contemporáneo transeccional y de campo en la cual se incluyeron 100 mujeres con infertilidad, separadas en dos grupos pareados en relación con el tipo de infertilidad, a las cuales se les determinó el perfil hormonal tiroideo: hormona estimuladora del tiroides (TSH), tiroxina libre (FT4) y triiodotiroxina libre (FT3). Resultados: No se evidenciaron diferencias estadísticas significativas entre las mujeres con IP o IS, en cuanto a edad, menarquía, sexarquía, número de parejas y tiempo de convivencia. En las mujeres con IP prevaleció el factor ovulatorio (50 %) seguido del tubo-peritoneal (34 %), mientras que entre las pacientes con IS el factor principal fue el tubo-peritoneal (38 %) seguido del ovulatorio (28 %); mostrando solamente el factor ovulatorio una diferencia significativa (p< 0,05). Se determinó que las pacientes con IP presentaron significativamente concentraciones más elevadas tanto de la TSH (3,14 ± 2,08 vs. 2,33 ± 1,59; p< 0,05) como de FT4 (1,19 ± 0,37 vs. 1,04 ± 0,25; p< 0,05); determinándose una prevalencia de HSC en mujeres infértiles del 17 %; siendo más frecuente y significativo en el grupo de mujeres con IP que en las pacientes con IS (26 % vs. 8 %; OR [IC95%]= 4,04 [1,26 -13,43]; p < 0,05), en tanto que según la severidad del HSC todos los casos detectados en ambos grupos se encontraban dentro del grado I. Conclusión: Existe una mayor prevalencia de HSC entre las mujeres con IP que en las pacientes con IS.

Objective: To compare the frequency of subclinical hypothyroidism (SCH) among women with primary (PI) and secondary infertility (SI) who presented for gynecology consultation at Maternity "Dr. Armando Castillo Plaza" in Maracaibo, Zulia state. Methods: Comparative and applied research with non-experimental, contemporary transactional and field design, including 100 women with infertility, separated into two groups matched for the type of infertility. Thyroid hormone profile: thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyroxine (FT3) were measured in these women. Results: There were no statistically significant differences between women with PI or secondary SI, in terms of age, menarche, sexarche, number of partners and length of cohabitation. In women with PI the ovulatory factor prevailed (50 %) followed by the tube-peritoneal (34 %), while among patients with SI the main factor was the tube-peritoneal (38 %) followed by the ovulatory (28 %); only the ovulatory factor showed a significant difference (p < 0.05). PI patients had significantly higher concentrations of both TSH (3.14 ± 2.08 vs. 2.33 ± 1.59, p <0.05) and FT4 (1.19 ± 0, 37 vs. 1.04 ± 0.25, p < 0.05); the prevalence of SCH was determined at 17% in infertile women, being more frequent and significant in the PI group of women than in SI patients (26 % vs. 8 %, OR [95 % CI] = 4.04 [1.26-13.43], p < 0.05), while according to the severity of SCH all cases detected in both groups were within grade I. Conclusion: There is a higher prevalence of SCH in women with PI than in patients with SI.

Hipotiroidismo subclínico en mujeres infértiles / Subclinical Hypothyroidism in Infertile Women

Objetivo: Comparar la frecuencia de hipotiroidismo subclínico (HSC) entre mujeres con infertilidad primaria (IP) y secundaria (IS) asistidas en la consulta de ginecología de la Maternidad “Dr. Armando Castillo Plaza”, en Maracaibo, estado Zulia. Métodos: Investigación comparativa y aplicada, con diseño de tipo no experimental, contemporáneo transeccional y de campo en la cual se incluyeron 100 mujeres con infertilidad, separadas en dos grupos pareados en relación con el tipo de infertilidad, a las cuales se les determinó el perfil hormonal tiroideo: hormona estimuladora del tiroides (TSH), tiroxina libre (FT4) y triiodotiroxina libre (FT3). Resultados: No se evidenciaron diferencias estadísticas significativas entre las mujeres con IP o IS, en cuanto a edad, menarquía, sexarquía, número de parejas y tiempo de convivencia. En las mujeres con IP prevaleció el factor ovulatorio (50 %) seguido del tubo-peritoneal (34 %), mientras que entre las pacientes con IS el factor principal fue el tubo-peritoneal (38 %) seguido del ovulatorio (28 %); mostrando solamente el factor ovulatorio una diferencia significativa (p< 0,05). Se determinó que las pacientes con IP presentaron significativamente concentraciones más elevadas tanto de la TSH (3,14 ± 2,08 vs. 2,33 ± 1,59; p< 0,05) como de FT4 (1,19 ± 0,37 vs. 1,04 ± 0,25; p< 0,05); determinándose una prevalencia de HSC en mujeres infértiles del 17 %; siendo más frecuente y significativo en el grupo de mujeres con IP que en las pacientes con IS (26 % vs. 8 %; OR [IC95%]= 4,04 [1,26 -13,43]; p < 0,05), en tanto que según la severidad del HSC todos los casos detectados en ambos grupos se encontraban dentro del grado I. Conclusión: Existe una mayor prevalencia de HSC entre las mujeres con IP que en las pacientes con IS.(AU)

Objective: To compare the frequency of subclinical hypothyroidism (SCH) among women with primary (PI) and secondary infertility (SI) who presented for gynecology consultation at Maternity "Dr. Armando Castillo Plaza" in Maracaibo, Zulia state. Methods: Comparative and applied research with non-experimental, contemporary transactional and field design, including 100 women with infertility, separated into two groups matched for the type of infertility. Thyroid hormone profile: thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyroxine (FT3) were measured in these women. Results: There were no statistically significant differences between women with PI or secondary SI, in terms of age, menarche, sexarche, number of partners and length of cohabitation. In women with PI the ovulatory factor prevailed (50 %) followed by the tube-peritoneal (34 %), while among patients with SI the main factor was the tube-peritoneal (38 %) followed by the ovulatory (28 %); only the ovulatory factor showed a significant difference (p < 0.05). PI patients had significantly higher concentrations of both TSH (3.14 ± 2.08 vs. 2.33 ± 1.59, p <0.05) and FT4 (1.19 ± 0, 37 vs. 1.04 ± 0.25, p < 0.05); the prevalence of SCH was determined at 17% in infertile women, being more frequent and significant in the PI group of women than in SI patients (26 % vs. 8 %, OR [95 % CI] = 4.04 [1.26-13.43], p < 0.05), while according to the severity of SCH all cases detected in both groups were within grade I. Conclusion: There is a higher prevalence of SCH in women with PI than in patients with SI.(AU)

Structural anomalies related to changes in the conduction mechanisms of α-Sm2(MoO4)3.

Polycrystalline samples of α-phase samarium molybdate were prepared by solid-state synthesis and used for x-ray diffraction (from 300 to 1000 K) and dielectric spectroscopy (from 500 to 900 K and from 10(2) to 10(6) Hz). The electrical conductivity follows the universal dielectric response, and three different regimes of conduction (with semiconductor, polaronic, and ionic characteristics) were ascribed. The polaronic mechanism in the range from 600 to 810 K was probed using the overlapping large polaron model. Above 810 K, the application of scaling laws suggests an ionic conductivity. The thermal dependence of the lattice parameter a shows three different trends in correspondence with the three conduction regimes observed. An analysis using adapted symmetry modes facilitated the Rietveld refinement and the study of the thermal dependence of the distortion arising from the oxygen displacements. We suggest that the transversal displacements of oxygen atoms in Sm-O-Mo bridges joined to the elongation of tetrahedra can help to explain this anomalous behavior. From the calculated bond-valence contour maps, new sites for the oxygen atoms, at higher temperatures, were detected which favor oxygen motion and would then be related to the ionic conduction. This correlation has been compared and extended to α-Eu(2)(MoO(4))(3).

Infertilidad tubárica e infección genital por Chlamydia trachomatis-Ureaplasma urealyticum / Genital infection and tubal infertility by Chlamydia tra-chomatis or Ureaplasma urealyticum

Objetivo: establecer la asociación entre la infertilidad tubarica y la infección cervical por Chlamydia trachomatis (CT) o Ureaplasma urealiticum (UU), en mujeres infértiles. Métodos: investigación comparativa y aplicada, con diseño de tipo no experimental, de casos y controles, contemporáneo transeccional y de campo, que incluyó 60 mujeres, separadas en dos grupos pareados de acuerdo si eran infértiles (casos) o fértiles (controles), a las cuales se les tomó una muestra de hisopado endocervical para el diagnóstico molecular de CT o UU y se les realizó una histerosalpingografía para evaluar la permeabilidad de las trompas uterinas. Resultados: se detectó una prevalencia en mujeres infértiles y fértiles de infección por CT o UU del 18 por ciento y 35 por ciento, respectivamente; siendo mayor entre las mujeres infértiles, diferencia significativa solo para UU (p<0,05). Se detectó una mayor permeabilidad tubárica en las pacientes fértiles que en las infértiles (80 por ciento vs. 40 por ciento), siendo el compromiso tubárico mayor en las pacientes infértiles (p<0,05). Al asociar el diagnóstico de CT o UU con los resultados de la histerosalpingografía se constató que la detección de uno de estos microorganismos aumentaba casi 3 o 5 veces más la probabilidad de presentar obstrucción tubárica, respectivamente, diferencias no significativas (p>0,05). Conclusión: una gran parte de las mujeres infértiles presentan infección por CT o UU, patógenos de transmisión sexual que pudiesen tener responsabilidad en el daño tubárico.

Objective: to establish the association between tubal infertility and cervical infection by Chlamydia tra-chomatis (CT) or Ureaplasma urealyticum (UU) in infertile women. Methods: a comparative, and applied research with a non-experimental, case-control, contemporary-transactional and field design, including 60 women, separated into two groups matched according whether they were infertile (cases) or fertile (controls), in which was took a sample of endocervical swabs for molecular diagnosis of cT or UU and underwent hysterosalpingography to assess the permeability of the fallopian tubes. Results: it was detected in infertile and fertile women a prevalence of CT or UU infection of 18 percent and 35 percent, respectively; being higher detection among infertile women, although this difference was significant only for UU (p <0.05). Also detected more tubal permeability in fertile patients that in infertile (80 percent vs. 40 percent), being higher in engagement tubal in infertility patients (p<0.05). By associating the diagnosis of both CT and UU with hysterosalpingography'sresults found that the diagnosis of one of these microorganisms increased almost 3 to 5 times more likely to have obstruction of the fallopian tubes, respectively; although this higher risk doesn't showed significance (p>0.05). Conclusion: a large proportion of infertile women have CT or UU infection, sexually transmitted pathogens that might have tubal damage liability.

Función sexual antes y después de la reparación quirúrgica del prolapso genital / Sexual function of women with genital prolapse before and after of surgical repair

Objetivo: comparar la función sexual (FS) de mujeres con prolapso genital (PG) antes y después de su reparación quirúrgica. Métodos: investigación de tipo comparativa y aplicada, con diseño cuasi experimental, prospectivo y de campo, donde se evaluó la FS de mujeres con diagnóstico de PG antes y después del tratamiento quirúrgico con técnicas convencionales, mediante el Cuestionario Sexual para Prolapso genital e Incontinencia Urinaria versión corta (PISQ-12). Resultados: al comparar la FS antes y después de la cirugía reparadora del PG, se determinó que tanto la puntuación total del PISQ-12 (15,90 +/- 6,51 vs. 32,17 +/- 3,62) como las puntuaciones de las dimensiones respuesta sexual (5,87 +/- 2,80 vs. 10,97 +/- 2,80) y limitaciones sexuales femeninas (4,88 +/- 3,90 vs. 16,77 +/- 3,00) fueron significativamente más altas luego de la intervención quirúrgica (p<0,001), a excepción del indicador intensidad del orgasmo (0,80 +/- 0,71 vs. 0,87+/- 0,73; p= 0,722) y la dimensión limitaciones sexuales de la pareja (4,37 +/- 2,14 vs. 3,56 +/- 2,70; p=0,815) donde sus puntuaciones antes y después del tratamiento quirúrgico no fueron estadísticamente significativas (p>0,05). Conclusiones: Lls mujeres con PG presentan una pobre FS, la cirugía reparadora del PG por técnicas convencionales mejoró significativamente la FS de las pacientes con disfunción del piso pélvico, permitiéndoles obtener a estas mujeres una vida sexual más placentera, con mejoría de su calidad de vida.

Objective: to compare sexual function (SF) of women with genital prolapse (GP) before and after surgical repair. Methods: this is a comparative and applied research with quasi-experimental, prospective and field design, which evaluated the SF of women diagnosed with PG before and after surgical treatment with conventional techniques, by the short version of the Prolapse and Incontinence Sexual Questionnaire (PISQ-12). Results: when comparing the SF before and after surgical repair of GP, it was determined that both the total score of PIQS-12 (15.90 +/- 6.51 vs. 32.17 +/- 3.62) and the scores of the dimensions: sexual response (5.87 +/- 2.80 vs. 10.97 +/- 2.80) and female sexual limitations (4.88 +/- 3.90 vs. 16.77 +/- 3.00) were significantly higher after surgery (p<0.001), except the indicator: orgasm intensity (0.80 +/- 0.71 vs. 0.87 +/- 0.73, p = 0.722) and the dimension partner's sexual limitations (4.37 +/- 2,14 vs. 3.56 +/- 2.70, p=0.815) where their scores before and after surgery showed no statistically significant differences (p>0.05). Conclusions: women with GP exhibit a poor SF, surgical repair of GP by conventional techniques significantly improves the SF of patients with pelvic floor dysfunction, allowing these women get sexual life more pleasant, which will impact on improving their quality of life.

A novel serine/threonine kinase gene, STK33, on human chromosome 11p15.3.

Human chromosomal region 11p15 is known to be associated with several diseases including predispositions to develop various tumor types. In search of candidate genes, a novel human kinase gene is described, STK33, which codes for a serine/threonine protein kinase. The gene was discovered by comparative genome analysis of human chromosome 11p15.3 and its orthologous region on distal mouse chromosome 7. Human STK33 gene contains 12 exons as has been determined by the comparison to the full-length transcript amplified from human uterus RNA. Transcripts are found in a variety of tissues in at least two alternatively spliced forms as revealed by reverse transcriptase-polymerase chain reaction, cDNA sequencing and expressed sequence tag clustering. Phylogenetic analysis suggests that STK33 may belong to the calcium/calmodulin-dependent protein kinase group, even though, like several other members of the group, it lacks the calcium/calmodulin binding domain [FASEB J. 9 (1995) 576]. STK33 shows a differential expression in a variety of normal and malignant tissues.

Exocytosis of a 60 kDa protein (calreticulin) from activated hamster oocytes.

The sp50 protein localized at the acrosomal region of guinea pig sperm was suggested to participate in acrosome exocytosis, the acrosome reaction (AR). On the other hand, the cortical reaction (CR), also an exocytotic event, occurs during egg activation. The aim of the present work was to identify sp50 and also to define if sp50 is present in hamster eggs, as well as its location before and after CR. Sp50 was identified as calreticulin (CRT), based on: (a) its NH(2)-terminal amino acid (25 aa) sequence, (b) a cross-recognition of pure sp50 and pure CRT with anti-CRT (from Santa Cruz, anti-CRTsc), and anti-sp50 (anti-sp50/CRT) antibodies, respectively, and (c) that both antibodies revealed a 50 kDa protein in a Brij sperm extract. On the other hand, CRT presence in eggs was positively determined by Western blotting (Wb) using anti-sp50/CRT antibody which recognized a 60 kDa protein in the egg extract, and by indirect immunofluorescence (IIF), CRT was located in the cortical granules (CG). It was defined by a granular pattern and co-localization with mannose, a specific carbohydrate of the CG. Additionally, a decrease in CRT concentration occurred in eggs after their activation and, in parallel, the protein was revealed in the egg's incubation medium. In activated eggs with zona pellucida (ZP), CRT remains as a halo in the perivitelline space and around the polar body. From these results we suggest that: (1) CRT is present in the CG of non-activated hamster eggs, (2) CRT is exocytosed during the CR, in response to egg activation, and (3) CRT might participate in the block to polyspermy, together with other CG components.

Comparative genomic sequencing reveals a strikingly similar architecture of a conserved syntenic region on human chromosome 11p15.3 (including gene ST5) and mouse chromosome 7.

Comparative genomics is a superior way to identify phylogenetically conserved features like genes or regions involved in gene regulation. The comparison of extended orthologous chromosomal regions should also reveal other characteristic traits essential for chromosome or gene function. In the present study we have sequenced and compared a region of conserved synteny from human chromosome 11p15.3 and mouse chromosome 7. In human, this region is known to contain several genes involved in the development of various disorders like Beckwith-Wiedemann overgrowth syndrome and other tumor diseases. Furthermore, in the neighboring chromosome region 11p15.5 extensive imprinting of genes has been reported which might extend to region 11p15.3. The analysis of approximately 730 kb in human and 620 kb in mouse led to the identification of eleven genes. All putative genes found in the mouse DNA were also present in the same order and orientation in the human chromosome. However, in the human DNA one putative gene of unknown function could be identified which is not present in the orthologous position of the mouse chromosome. The sequence similarity between human and mouse is higher in transcribed and exon regions than in non-transcribed segments. Dot plot analysis, however, reveals a surprisingly well-conserved sequence similarity over the entire analyzed region. In particular, the positions of CpG islands, short regions of very high GC content in the 5' region of putative genes, are similar in human and mouse. With respect to base composition, two distinct segments of significantly different GC content exist as well in human as in the mouse. With a GC content of 45% the one segment would correspond to "isochore H1" and the other segment (39% GC in human, 40% GC in mouse) to "isochore L1/L2". The gene density (one gene per 66 kb) is slightly higher than the average calculated for the complete human genome (one gene per 90 kb). The comparison of the number and distribution of repetitive elements shows that the proportion of human DNA made up by interspersed repeats (43.8%) is significantly higher than in the corresponding mouse DNA (30.1%). This partly explains why the human DNA is longer between the landmark genes used to define the orthologous positions in human and mouse.

Comparative distribution of short dystrophin superfamily products in various guinea pig spermatozoa domains.

In this study, the presence and cellular distribution of dystrophin family products (i.e. Dp71d, Dp71f-like protein and dystrobrevin) was examined by indirect immunofluorescence and Western blotting in guinea pig spermatozoa. Two dystrophin-associated proteins, beta-dystroglycan and alpha-syntrophin, and nNOS a protein frequently associated with alpha-syntrophin, were determined. In spermatozoa lacking plasma membrane and acrosome, Dp71f-like protein was found in the postacrosomal perinuclear theca and also in the middle piece of the flagellum. In the flagellum, Dp71f-like protein is localized together with alpha-syntrophin and nNOS. Dp71d was present in the plasma membrane of the middle piece with beta-dystroglycan, alpha-syntrophin and nNOS. Dp71d was also present in plasma membrane of the post acrosomal region, but only with nNOS. Finally, dystrobrevin was located all along skeletal flagellum structures and in the subacrosomal hemisphere of the perinuclear theca. This distinct and complementary distribution in various domains of spermatozoa may reveal a specific function for each short dystrophin family product, in the stabilization of the domains where they are located.

Involvement of an F-actin skeleton on the acrosome reaction in guinea pig spermatozoa.

The acrosome reaction (AR) is a regulated exocytotic process. In several cell types, an actin network situated under the plasma membrane (PM) acts as a physical barrier to prevent this exocytosis. In seeking a function for a cortical skeleton in guinea pig spermatozoa, the PM and the outer acrosomal membrane (OAM) were investigated for the presence of F-actin and spectrin, proteins generally found in cell cortical skeletons. Both membrane types were visualized in whole-mount preparations by electron microscopy. PM proteins gave positive reaction to the Na(+),K(+)-ATPase antibody and the OAM proteins did not react to the antibody. Furthermore, a Triton X-100-resistant skeleton was obtained from both membrane types. Using gold immunoelectron microscopy, F-actin was visualized in the PM and in the OAM skeletons, while spectrin was only detected in the PM skeleton. The presence of an F-actin cortical skeleton in the sperm PM suggests that F-actin may be involved in the AR. The significantly higher number of AR elicited by cytochalasin D (Cyt-D) treatment(P<0.005) and data showing a significant (P>0.03) decrease in F-actin relative concentration in capacitating spermatozoa, agree with this suggestion. Furthermore, the proposal is strengthened by the fact that stabilization of F-actin by phalloidin (Ph) significantly (P>0.01) diminished AR induced by Ca(2+) in a streptolysin O (SLO)-permeabilized sperm model.

Phytochemical, morphological, and biological investigations of propolis from Central Chile.

Propolis from central Chile was investigated for its plant origin by microscopical analysis of pollen grains and leaf fragments found in the sample. The pollen grains that appear with significant higher frequency in the sample corresponded to four native and two introduced species, whereas leaf fragments corresponded to four native species. Seventeen phenolic compounds that belong to the phenylpropane, benzaldehyde, dihydrobenzofuran, or benzopyran classes, were isolated from an organic extract that was found to have a moderate growth inhibitory activity against Mycobacterium avium, M. tuberculosis, and two strains of Staphylococcus aureus. The components responsible for activity were determined.

A perinuclear theca substructure is formed during epididymal guinea pig sperm maturation and disappears in acrosome reacted cells.

The perinuclear theca (PT) is a unique cytoskeletal mammalian sperm structure that surrounds the nucleus. Using negatively stained whole-mount preparations, we detected a PT substructure on the apical region of the postacrosomal theca layer of guinea pig spermatozoa. The PT substructure consists of projections resembling eyelashes, circling the sperm head. The PT substructure was absent in caput but appeared in corpus epidydimal spermatozoa. The same finding was observed in sheep and rabbit spermatozoa. The PT substructure persisted in capacitating spermatozoa, but was absent in acrosome reacted gametes. No labeling of the PT substructure was observed by the immunogold technique using antibodies against calmodulin, spectrin, myosin, and vimentin. A 34-kDa band appeared as a possible PT substructure protein. The PT was positive to the antibodies and the presence of the above-mentioned proteins was confirmed by Western blot. F-actin gold label was observed in mature spermatozoa on the PT substructure base zone. Results using cytochalasin D and phalloidin point to a role of F-actin in the PT substructure formation/disassembly processes. Ca(2+), bicarbonate, and proteases might be involved in the mechanism of the substructure disassembly. Novel PT morphological changes occurring during sperm epidydimal maturation and at acrosome reaction, respectively, are discussed in relation to the PT stability and function.

Sperm protein (sp50) binds to acrosome and plasma membranes in a Ca(2+)-dependent manner: possible role in acrosome reaction.

Annexins are a family of Ca(2+)-binding proteins involved in the exocytotic process. The presence and the role of annexins in mammalian spermatozoa have not been well established. Two annexin-like proteins were obtained from guinea pig testis, a doublet of Mr 31-33 kD (p31/33) and a protein of Mr 50 kD (p50). Both proteins were able to bind to erythrocyte ghosts in a Ca(2+)-dependent fashion. Polyclonal antibodies against p31/33 reacted with two major proteins, Mrs 50 kD (sp50) and 42 kD (sp42), from mature and immature guinea pig spermatozoa. p50 and sp50 are likely the native proteins from testis and spermatozoa, respectively, and they are seemingly related. By immunofluorescence, sp50 was only found in the acrosome region of immature and capacitated and noncapacitated spermatozoa, and its location was intracellular. In spermatozoa undergoing acrosome reaction, sp50 was detected in the whole acrosome, while in spermatozoa that had undergone acrosome reaction sp50 was not detected. However, in the protein pattern of acrosome reaction vesicles, anti-p31/33 antibody revealed diffuse bands of Mr 35-38 kD. sp50 was able to bind to plasma membrane fragments and acrosome outer membrane from demembranated sperm in a Ca(2+)-dependent fashion. The presence of sp50 in the acrosome region, its distribution throughout the acrosome membrane just before the acrosome reaction, and its ability to bind both plasma and outer acrosome membranes in a Ca(2+)-dependent manner suggest that sp50 may participate in the acrosome reaction mechanism in guinea pig spermatozoa.

Ouabain resistance of the epithelial cell line (Ma104) is not due to lack of affinity of its pumps for the drug.

Na+, K(+)-pumps of most eukaryotic animal cells bind ouabain with high affinity, stop pumping, and consequently loose K+, detach from each other and from the substrate, and die. Lack of affinity for the drug results in ouabain resistance. In this work, we report that Ma104 cells (epithelial from Rhesus monkey kidney) have a novel form of ouabain-resistance: they bind the drug with high affinity (Km about 4 x 10(-8) M), they loose their K+ and stop proliferating but, in spite of these, up to 100% of the cells remain attached in 1.0 microM ouabain, and 53% in 1.0 mM. When 4 days later ouabain is removed from the culture medium, cells regain K+ and resume proliferation. Strophanthidin, a drug that attaches less firmly than ouabain, produces a similar phenomenon, but allows a considerably faster recovery. This reversal may be associated to the fact that, while in ouabain-sensitive MDCK cells Na+, K(+)-ATPases blocked by the drug are retrieved from the plasma membrane, those in Ma104 cells remain at the cell-cell border, as if they were cell-cell attaching molecules. Cycloheximide (10 micrograms/ml) and chloroquine (10 microM) impair this recovery, suggesting that it also depends on the synthesis and insertion of a crucial protein component, that may be different from the pump itself. Therefore ouabain resistance of Ma104 cells is not due to a lack of affinity for the drug, but to a failure of its Na+, K(+)-ATPases to detach from the plasma membrane in spite of being blocked by ouabain.

Calmodulin binding proteins in the membrane vesicles released during the acrosome reaction and in the perinuclear material in isolated acrosome reacted sperm heads.

Calmodulin has been suggested as the Ca(2+)-mediator in diverse cellular functions via its interaction with a number of proteins in a calcium-dependent manner. Its participation in the acrosome reaction has been suggested based on its localization in the acrosome region, on the effects produced by calmodulin antagonists, and by the changes in calmodulin compartmentation observed to occur throughout guinea pig acrosome reaction. To define the role of calmodulin in the membrane fusion events that occur during the acrosome reaction, the identification of calmodulin-binding proteins, by the overlay technique with biotinylated or unmodified calmodulin, was made in the following sperm fractions: in the membrane vesicles released during the acrosome reaction, in the remaining perinuclear material of acrosome reacted sperm heads and in a total membrane fraction from intact spermatozoa. The membrane vesicles released after the acrosome reaction showed four major calmodulin-binding proteins, M(r)s 66, 95, 97 and 110 kDa. The perinuclear material showed a 31-34, 43 and 97 kDa calmodulin-binding polypeptides. The membrane fraction from intact sperm showed eleven calmodulin-binding proteins, M(r)s between 14-110 kDa. Most of the binding proteins detected by this method corresponded to the class of calcium-independent calmodulin-binding proteins but proteins which only interacted with calmodulin in a calcium-inhibited mode were also observed. No calcium-dependent calmodulin-binding proteins were detected in any of the fractions studied. A possible role of these binding proteins in calmodulin compartmentation is discussed. The potential role of these binding proteins in membrane fusion and in membrane receptor localization in the postacrosomal region remain to be defined.