Buoyant density centrifugation of sea urchin embryo chromatin on sucrose-glucose gradient

Unsheard chromatin isolated from sea urchin embryos was submitted to buoyant density centrifugation in sucrose-glucose gradients. The main peak of blastula chromatin was at a density position of 1.299±0.028±0.009 g ml^-1 whereas at gastrula stage a shift to a lower buoyant density position of (1.276±0.021±0.007 g ml^-1) was observed. Besides the main peak, a small band with a density of 1.18 g ml^-1 was noticed. The lighter fraction differed from the heavy one in a higher histone to DNA ratio, a lower proportion of the F-1 histone, and a lower nonhistone to DNA ratio. The most pronounced developmental alterations of proteins were observed at the level of nonhistone protein patterns of the light fractions.     

The study of proteins during early stages of embryogenesis of sea urchins

Summary The distribution of the preexisting and of thede novo synthesized proteins among soluble, and insoluble fractions, as well as between immunoprecipitable and non-immunoprecipitable soluble proteins has been studied in sea urchin embryos at different stages of development.In the S-100 fraction, which represented about 20% of total proteins, only a minor part of radioactivity was found. The majority of newly synthesized proteins was insoluble at neutral pH. Such distribution was practically invariant for all investigated stages of development, and was not markedly affected by Dactinomycin nor by 5-azacytidine.Only a small percentage of the total radioactivity of the S-100 fraction was found in the antigen-antibody complexes of soluble proteins. No shift of newly synthesized proteins towards the type of old, preexisting antigenic proteins was detected, and the majority of soluble newly synthesized proteins was found to be related to the non-immunoprecipitable soluble proteins.The authors gratefully acknowledge a generous gift of 5-azacytidine from Drs. Doskoil and ponar. We are also indebted to Dr. Miroslav Simi for kind interest and discussion.This work was supported in part by grants No 3111/1 from Federal Research Fund of Yugoslavia and No 02-020-1 from the National Institute of Health, U. S. Department of Health, Education and Welfare (PL-480 programme).     

Species-dependent changes in stomatal sensitivity to abscisic acid mediated by external pH

The direct effects of pH changes and/or abscisic acid (ABA) on stomatal aperture were examined in epidermal strips of Commelina communis L. and Arabidopsis thaliana. Stomata were initially opened at pH 7 or pH 5. The stomatal closure induced by changes in external pH and/or ABA (10 microM or 10 nM) was monitored using video microscopy and quantified in terms of changes in stomatal area using image analysis software. Measurements of aperture area enabled stomatal responses and, in particular, small changes in stomatal area to be quantified reliably. Both plant species exhibited a biphasic closure response to ABA: an initial phase of rapid stomatal closure, followed by a second, more prolonged, phase during which stomata closure proceeded at a slower rate. Changes in stomatal sensitivity to ABA were also observed. Comparison of these effects between C. communis and A. thaliana demonstrate that this differential sensitivity of stomata to ABA is species-dependent, as well as being dependent on the pH of the extracellular environment.     

Of mice and men: teratomas and teratocarcinomas

Teratomas and teratocarcinomas are tumors containing tissue derivatives of all three germ-layers. They can be induced by transplantation of animal embryos to ectopic microenvironment. Development of malignant teratocarcinomas depends on embryonic stage, species-specificity and immunological competence of the host. In the man, teratomas and teratocarcinomas usually represent a subtype of germ-cell tumors but sacrococcygeal teratomas arise from the remnants of the pluripotent primitive streak. Undifferentiated embryonal carcinoma (EC) cells are responsible for the malignancy of experimental mouse teratocarcinomas. Mouse EC cells injected to the adult give rise to tumors and upon injection to early embryos to differentiated tissues--thus resembling normal mouse embryonic stem cells (mESC). Epigenetic changes rather than mutations are associated with transformation of mESC to EC cells. Human EC and ES cell-lines (hESC) contain chromosomal abnormalities and can form teratocarcinoma after transplantation. ES cells are among those proposed for cell replacement therapy in the man. Suicide gene introduction should be recommended prior to their use in vivo to ablate them in case of malignant transformation.     

Changes of adolescents' defence mechanisms during the first year of high school education

The goal of this study was to analyse the defence mechanism's changes during adolescent's adaptation to the new schooling terms at the first year in high school. Sample of 266 students, mean age 15, have been included in the research. Kellerman's Life Style Questionnaire (LSQ) was administred for measuring defence mechanisms at the beginning and at the end of the school year. Results show that regression and reactive formation are changing at most; regression raises (p < 0.005) while reactive formation decreases (p < 0.000). Boys used repression, while girls reactive formation more frequently in both measuring. Displacement was 'male" defence in the first measuring; but at repeated measuring this difference in sex vanished. The sources of anxiety can be found partly in new school environment and in adolescent's effort to "solve the problem" with sexual impulses and aggression using different sets of defences.     

When do meadow vipers (Vipera ursinii) become sexually dimorphic? – ontogenetic patterns of sexual size dimorphisms

Contrary to an increasing number of papers that document sexual dimorphism in size (and/or shape) in adults, studies dealing with sex differences in newborn and juvenile snakes are surprisingly scarce. Data about ontogenetic shifts in sexual dimorphism are generally lacking and hence, it is unclear whether sex differences are set at birth or arise post‐natally. In this study, we analyzed patterns of sexual dimorphism in body size, head dimensions and tail length (TL) among newborn, subadult and adult meadow vipers (Vipera ursinii) from the Bjelasica Mt. in Montenegro. Patterns of sexual size dimorphisms differed among traits. There was no significant difference in head dimension of males and females, but adult snakes were sexually dimorphic in body size. Sexual differences in TL were evident since birth but changed in degree throughout ontogeny. Neonate meadow vipers presented highly significant inter‐litter variation in the sexual dimorphism of all traits we have measured. Such family effects may have an important influence on extent of inter‐sexual differences in snakes and should be included in analyses of sexual dimorphism.     

Lower lobe pulmonary tuberculosis in immunocompetent male

We present a case of 23-year-old student misdiagnosed for two months. Radiological finding showed a pneumonial infiltrate of left lung lower lobe. Antibiotical therapy was not resulting in a radiological regression. Biopsy of the lung infiltrate by transthoracic computed tomography guided histology needle, showed granulomatous inflammation with necrosis. Bronchial aspirate received by bronchoscopy was positive in culture on Mycobacterium tuberculosis. After 6 months of antituberculotic therapy advance the complete regression of lung infiltrate. Tuberculosis of lower lung lobe is difficult to diagnose, particularly in persons who are not immunocompromised or without associated diseases. Lower lobe localization of tuberculosis is between 0.6 to 10.5% in all cases. Early diagnosis and therapy of pulmonary tuberculosis depends on bronchoscopic samples. The biopsy of the lung infiltrate by transthoracic computed tomography guided histology needle in histopathological and bacteriological diagnosis of tuberculosis was also useful.     

Effect of alternating the magnetic field on phosphate metabolism in the nervous system of Helix pomatia

The effect of extremely low frequency magnetic fields (50 Hz, 0.5 mT) - ELF-MF, on phosphate metabolism has been studied in the isolated ganglions of the garden snail Helix pomatia, after 7 and 16 days of snail exposure to ELF-MF. The influence of ELF-MF on the level of phosphate compounds and intracellular pH was monitored by 31P NMR spectroscopy. Furthermore, the activity of enzymes involved in phosphate turnover, total ATPases, Na+/K+-ATPase and acid phosphatase has been measured. The exposure of snails to the ELF-MF for the period of 7 days shifted intracellular pH toward more alkaline conditions, and increased the activity of investigated enzymes. Prolonged exposure to the ELF-MF for the period of 16 days caused a decrease of PCr and ATP levels and decreased enzyme activity, compared to the 7-day treatment group. Our results can be explained in terms of: 1. increase in phosphate turnover by exposure to the ELF-MF for the period of 7 days, and 2. adaptation of phosphate metabolism in the nervous system of snails to prolonged ELF-MF exposure.     

Stereospecific ligands and their complexes. V. Synthesis, characterization and antimicrobial activity of palladium(II) complexes with some alkyl esters of (S,S)-ethylenediamine-N,N′-di-2-propanoic acid

Three new ligands and their palladium(II) complexes of general formula [PdCl₂(R₂-S,S-eddp)] (R = n-propyl, n-butyl and n-pentyl) have been synthesized and characterized by microanalysis, infrared and ¹H and ¹³C NMR spectroscopy. Antimicrobial activity of these ligands and complexes was tested by microdilution method and both minimal inhibitory and microbicidal concentration were determined. These tested complexes demonstrated the significant antifungal activity against pathogenic fungi Aspergillus flavus and Aspergillus fumigatus. On the other hand, these complexes demonstrated moderate antibacterial activity.     

Two-dimensional liquid chromatography system for online top-down mass spectrometry

An online metal-free weak cation exchange-hydrophilic interaction LC/RPLC system has been developed for sensitive, high-throughput top-down MS. Here, we report results for analyzing PTMs of core histones, with a focus on histone H4, using this system. With just ～24?μg on-column of core histones (H4, H2B, H2A, and H3) purified from human fibroblasts, 41 H4 isoforms were identified, with the type and location of PTMs unambiguously mapped for 20 of these variants. Compared to corresponding offline studies reported previously, the online weak cation exchange-hydrophilic interaction LC/RPLC platform offers significant improvement in sensitivity, with several orders of magnitude reduction in sample requirements and a reduction in the overall analysis time. To the best of our knowledge, this study represents the first online 2-D LC-MS/MS characterization of core histone mixture at the intact protein level.