p38gamma regulates the localisation of SAP97 in the cytoskeleton by modulating its interaction with GKAP

Activation of the p38 MAP kinase pathways is crucial for the adaptation of mammalian cells to changes in the osmolarity of the environment. Here we identify SAP97/hDlg, the mammalian homologue of the Drosophila tumour suppressor Dlg, as a physiological substrate for the p38gamma MAP kinase (SAPK3/p38gamma) isoform. SAP97/hDlg is a scaffold protein that forms multiprotein complexes with a variety of proteins and is targeted to the cytoskeleton by its association with the protein guanylate kinase-associated protein (GKAP). The SAPK3/p38gamma-catalysed phosphorylation of SAP97/hDlg triggers its dissociation from GKAP and therefore releases it from the cytoskeleton. This is likely to regulate the integrity of intercellular-junctional complexes, and cell shape and volume in response to osmotic stress.     

Biglycan is a new extracellular component of the Chordin-BMP4 signaling pathway

The BMP4 signaling pathway plays key roles during early embryonic development and for maintenance of adult homeostasis. In the extracellular space, BMP4 activity is regulated by a group of interacting molecules including the BMP antagonist Chordin, the metalloproteinase Tolloid and Twisted gastrulation (Tsg). In this study, we identified Biglycan (Bgn), a member of the small leucine-rich proteoglycan family, as a new extracellular modulator of BMP4 signaling. Xenopus Bgn (xBgn) is expressed uniformly in the ectoderm and mesoderm and their derivatives during development. Microinjection of Bgn mRNA induced secondary axes, dorsalized the mesoderm and inhibited BMP4 activity in Xenopus embryos. Biochemical experiments showed that Bgn binds BMP4 and Chordin, interaction that increased binding of BMP4 to Chordin. Bgn was also able to improve the efficiency of Chordin-Tsg complexes to block BMP4 activity. Using antisense morpholinos, we demonstrated that Bgn required Chordin to induce double axes in Xenopus. This work unveiled a new function for Bgn, its ability to regulate BMP4 signaling through modulation of Chordin anti-BMP4 activity.     

Alteration of cytosolic free calcium homeostasis by SIN-1: high sensitivity of L-type Ca2+ channels to extracellular oxidative/nitrosative stress in cerebellar granule cells

Exposure of cerebellar granule neurones in 25 mm KCl HEPES-containing Locke's buffer (pH 7.4) to 50-100 microm SIN-1 during 2 h decreased the steady-state free cytosolic Ca2+ concentration ([Ca2+]i) from 168 +/- 33 nm to 60 +/- 10 nm, whereas exposure to > or = 0.3 mm SIN-1 produced biphasic kinetics: (i) decrease of [Ca2+]i during the first 30 min, reaching a limiting value of 75 +/- 10 nm (due to inactivation of L-type Ca2+ channels) and (ii) a delayed increase of [Ca2+]i at longer exposures, which correlated with SIN-1-induced necrotic cell death. Both effects of SIN-1 on [Ca2+]i are blocked by superoxide dismutase plus catalase and by Mn(III)tetrakis(4-benzoic acid)porphyrin chloride. Supplementation of Locke's buffer with catalase before addition of 0.5-1 mm SIN-1 had no effect on the decrease of [Ca2+]i but further delayed and attenuated the increase of [Ca2+]i observed after 60-120 min exposure to SIN-1 and also protected against SIN-1-induced necrotic cell death. alpha-Tocopherol, the potent NMDA receptor antagonist (+)-MK-801 and the N- and P-type Ca2+ channels blocker omega-conotoxin MVIIC had no effect on the alterations of [Ca2+]i upon exposure to SIN-1. However, inhibition of the plasma membrane Ca2+ ATPase can account for the increase of [Ca2+]i observed after 60-120 min exposure to 0.5-1 mm SIN-1. It is concluded that L-type Ca2+ channels are a primary target of SIN-1-induced extracellular nitrosative/oxidative stress, being inactivated by chronic exposure to fluxes of peroxynitrite of 0.5-1 microm/min, while higher concentrations of peroxynitrite and hydrogen peroxide are required for the inhibition of the plasma membrane Ca2+ ATPase and induction of necrotic cell death, respectively.     

Trichomonas vaginalis: identification of soluble and membrane-associated phospholipase A1 and A2 activities with direct and indirect hemolytic effects

A direct hemolytic activity, dependent on phospholipase A (PLA) activity, was located in the particulate subcellular fraction (P30) of Trichomonas vaginalis. We identified soluble direct and indirect hemolytic activities in the spent medium and soluble fraction (S30) of T. vaginalis strain GT-13. Spent medium showed the highest specific indirect hemolytic activity (SIHA) at pH 6.0 (91 indirect hemolytic units [HU]/mg/hr). Spent medium and P30, but not S30, showed direct hemolytic activity. PLA activity was protein dose dependent and time dependent. The highest PLA activity was observed at pH 6.0. All trichomonad preparations showed phospholipase A1 (PLA A1) and phospholipase A2 (PLA A2) activities. Indirect and direct hemolytic activity and PLA A1 and PLA A2 diminished at pH 6.0 and 8.0 with increasing concentrations of Rosenthal's inhibitor. The greatest effect was observed with 80 microM at pH 6.0 on the SIHA of S30 (83% reduction) and the lowest at pH 8.0, also on the SIHA of S30 (26% reduction). In conclusion, T. vaginalis contains particulate and soluble acidic, and alkaline direct and indirect hemolytic activities, which are partially dependent on alkaline or acidic PLA A1 and PLA A2 enzymes. These could be responsible for the contact-dependent and -independent hemolytic and cytolytic activities of T. vaginalis.     

Introduction and Institutionalization of Genetics in Mexico Ana Barahona,Susana Pinar and Francisco J. Ayala

We explore the distinctive characteristics of Mexico’s society, politics and history that impacted the establishment of genetics in Mexico, as a new disciplinary field that began in the early 20th century and was consolidated and institutionalized in the second half. We identify about three stages in the institutionalization of genetics in Mexico. The first stage can be characterized by Edmundo Taboada, who was the leader of a research program initiated during the Cárdenas government (1934–1940), which was primarily directed towards improving the condition of small Mexican farmers. Taboada is the first Mexican post-graduate investigator in phytotechnology and phytopathology, trained at Cornell University and the University of Minnesota, in 1932 and 1933, respectively. He was the first investigator to teach plant genetics at the National School of Agriculture and wrote the first textbook of general genetics, Genetics Notes, in 1938. Taboada’s most important single genetics contribution was the production of “stabilized” corn varieties. The extensive exile of Spanish intellectuals to Mexico, after the end of Spain’s Civil War (1936–1939), had a major influence in Mexican science and characterizes the second stage. The three main personalities contributing to Mexican genetics are Federico Bonet de Marco and Bibiano Fernández Osorio Tafall, at the National School of Biological Sciences, and José Luis de la Loma y Oteyza, at the Chapingo Agriculture School. The main contribution of the Spanish exiles to the introduction of genetics in Mexico concerned teaching. They introduced in several universities genetics as a distinctive discipline within the biology curriculum and wrote genetics text books and manuals. The third stage is identified with Alfonso León de Garay, who founded the Genetics and Radiobiology Program in 1960 within the National Commission of Nuclear Energy, which had been founded in 1956. The Genetics and Radiobiology Program rapidly became a disciplinary program, for it embraced research, teaching, and training of academics and technicians. The Mexican Genetics Society, created by de Garay in 1966, and the development of strains and cultures for genetics research were important activities. One of de Garay’s key requirements was the compulsory training of the Program’s scientists for at least one or two years in the best universities of the United States and Europe. De Garay’s role in the development of Mexican genetics was fundamental. His broad vision encompassed the practice of genetics in all its manifestations.     

Breast pathology and reduction mammaplasty

Breast cancer is the tumor with the highest prevalence and incidence in women. Reduction mammaplasty is one of the most common procedures performed in Brazil by the plastic surgeon, and it is not uncommon for the surgeon to find a breast tumor during the operation or afterward, when the histopathological report is received. In this study, 2488 patient files were reviewed retrospectively. All patients had undergone reduction mammaplasty at the senior author's private clinic (the Ivo Pitanguy Clinic) between January of 1957 and December of 2002. Resected breast tissue was examined histopathologically. The objective of this study was to verify the occurrence of breast carcinoma found accidentally postoperatively. The senior author's team performed all of the operations and the same pathologist performed every histopathological examination. The histopathological test results were divided into two groups: benign lesions and tumors. The highest frequency of breast pathology was benign lesions, and of them, 80.8 percent involved fibrocystic changes and fibroadiposity. The tumor group was subdivided into benign tumors and malignant tumors. Among the benign tumors, fibroadenoma was the one most common, in 2.2 percent. The frequency of malignant tumors was 0.5 percent of all patients. Most of the histopathological lesions were found in patients between 30 and 50 years of age. A reduced number of patients had no lesions (3.7 percent). Lack of a pathological investigation or a cursory or hurried examination of any mammary tissue by the pathologist may overlook important lesions. In the analysis of these statistics, the concept of normal breast tissue was questioned.     

In vivo expression of a Cicer arietinum beta-galactosidase in potato tubers leads to a reduction of the galactan side-chains in cell wall pectin

We report the generation of Solanum tuberosum transformants expressing Cicer arietinum betaIII-Gal. betaIII-Gal is a beta-galactosidase able to degrade cell wall pectins during cell wall loosening that occurs prior to cell elongation. cDNA corresponding to the gene encoding this protein was identified among several chickpea beta-galactosidase cDNAs, and named CanBGal-3. CanBGal-3 cDNA was expressed in potato under the control of the granule-bound starch synthase promoter. Three betaIII-Gal transformants with varying levels of expression were chosen for further analysis. The transgenic plants displayed no significant altered phenotype compared to the wild type. However, beta-galactanase and beta-galactosidase activities were increased in the transgenic tuber cell walls and this affected the potato tuber pectins. A reduction in the galactosyl content of up to 50% compared to the wild type was observed in the most extreme transformant, indicating a reduction of 1,4-beta-galactan side-chains, as revealed by analysis with LM5 specific antibodies. Our results confirm the notion that the pectin-degrading activity of chickpea betaIII-Gal reported in vitro also occurs in vivo and in other plants, and confirm the involvement of betaIII-Gal in the cell wall autolysis process. An increase in the homogalacturonan content of transgenic tuber cell walls was also observed by Fourier transform infrared spectroscopy (FTIR) analysis.