Changes In Pattern Of Protein Synthesis Research Articles

Impact of UV-B radiation on antioxidant enzymes and protein electrophoretic pattern of the green algaChlorococcum sp.

The impact of two intensities (2.5 and 5 W m−2) of ultraviolet-B (UV-B) radiation on lipid peroxidation, protein pattern and some antioxidant enzymes including superoxide dismutase, catalase and peroxidase has been studied inChlorococcum sp. isolated from El-Kased freshwater canal, Tanta, Egypt. Exposure ofChlorococcum sp. for 2 h to 2.5 and 5 W m−2 increased malondialdehyde (MDA) content by 238 and 274%, respectively. The activity of superoxide dismutase and peroxidase were increased at all exposure times at both intensities. In contrast, the activity of catalase was inhibited by increasing UV-B intensity as well as exposure time compared to the control. The reduction in catalase activity reached 71.8 and 95.9% after 2 h of exposure to 2.5 and 5 W m−2, respectively. With regard to protein pattern, exposure ofChlorococcum sp. to UV-B stress induced marked changes in protein synthesis patterns. Three types of alterations were noticed, i) significant reduction in the biosynthesis of certain proteins, ii) induction of specific proteins biosynthesis and iii) changes in band intensities of some proteins.

Proteome analysis of salt stress response in the cyanobacteriumSynechocystis sp. strain PCC 6803

In the present study, changes in protein synthesis patterns after salt shock visualized by 35S-methionine labeling and the changed protein composition in salt-acclimated cells of the cyanobacterium Synechocystis sp. strain PCC 6803 were analyzed by a combination of 2-DE for protein separation and PMF for protein identification. As a basis for the differential analysis, a proteome map with 500 identified protein spots comprising 337 different protein species was established. Fifty-five proteins were found, which are induced by salt shock or accumulated after long-term salt acclimation. Some of the proteins are salt stress-specific, such as enzymes involved in the synthesis of the compatible solute glucosylglycerol, while most of them are involved in general stress acclimation. Particularly, heat-shock proteins and proteins acting against lesions by reactive oxygen species were found. Moreover, changes in enzymes involved in basic carbohydrate metabolism were detected. The dynamic of the proteome of salt-stressed Synechocystis cells was compared to previous data concerning transcriptome analysis revealing that 89% of the proteins induced shortly after salt shock were also found to be induced at the RNA level. However, 42% of the stably up-regulated proteins in salt-acclimated cells were not detected previously using DNA microarrays. The comparison of transcriptomic and proteomic analyses shows the significance of post-transcriptional regulatory mechanisms in acclimation of Synechocystis to high salt concentrations.

Nuclear and Cytoplasmic Maturation of Human Oocytes Cultured in a Serum and Albumin Free Chemically Defined Medium

Objectives: It has been suggested that use of a medium containing serum or albumin for culture of human ova may confound outcome of results and could introduce unfavorable molecules or pathogens into the culture system because serum or serum albumin contains numerous proteins and unknown factors. Therefore, it is desirable to develop a serum and albumin free, chemically defined medium. The objectives of this study were 1) to assess fertilization and development of human oocytes cultured in a chemically defined medium (CDM); 2) to evaluate chromatin and spindle configuration of the IVM oocytes; and 3) to investigate changes in protein synthesis pattern of the IVM oocytes.

Alterations in Protein Synthesis Following Transplantation of Mouse 8-Cell Stage Nuclei to Enucleated 1-Cell Embryos

Enucleated mouse 1-cell embryos arrest development at the 2-cell stage following transplantation of cleavage stage nuclei. Earlier studies employing one-dimensional protein gel electrophoresis failed to reveal obvious differences in gene expression in the manipulated embryos that might account for this block. We report here the results of a quantitative, two-dimensional gel electrophoretic analysis that reveals at least 50 alterations in protein synthesis in the 8 → 1-cell nuclear transplant embryos. Approximately half of these alterations involve proteins that normally decrease in synthesis between the 2-cell and 8-cell stages and half involve proteins that are synthesized constitutively between these two stages. These results are the first to reveal significant biochemical alterations that accompany the morphological and cytological differences previously described and indicate that the 8-cell stage nucleus is unable to completely recapitulate the normal progression of changes in protein synthesis pattern that occur during the 2-cell stage. Our results indicate that developmental arrest may result from a combination of (1) failure to re-activate genes that normally become repressed between the 2-cell and 8-cell stages and (2) failure to up-regulate genes that become repressed during reprogramming of the 8-cell nucleus by the 1-cell cytoplasm. The failure to up-regulate the synthesis of proteins expressed at both the 2-cell and the 8-cell stages may indicate that, for some genes, a transcriptionally inactive state, possibly related to a particular chromatin configuration, may serve a protective function by restricting access of factors that can permanently reduce the ability of a gene to be expressed. This may partially account for the need to delay the widespread activation of zygotic gene transcription until the 2-cell stage, when much of the nuclear remodeling that occurs postfertilization is complete.

Changes in protein synthesis pattern during in vitro maturation of goat oocytes.

The regulation of meiotic events of goat oocytes from prophase I to metaphase II was studied by inhibiting protein synthesis at different times of the transition and by analyzing the changes in the protein synthesis pattern during maturation. Protein synthesis was required for germinal vesicle breakdown (GVBD). Nevertheless, the concomitant event to the rupture of germinal vesicle, i.e., chromosome condensation, took place even in a cycloheximide-containing medium. The transition from metaphase I to metaphase II was also protein synthesis dependent as evidenced by experiments using this protein synthesis inhibitor. The inhibition was partly reversible, i.e., after removal of the drug, oocytes were able to progress until metaphase I but could not proceed beyond this stage. Changes in the protein synthesis pattern were studied by radiolabelling of oocytes with [35S]methionine. These changes were correlated with the nuclear status of the oocyte: At GVBD, a polypeptide of 25 kD disappeared, while one of 27 kD appeared. At the same time, a polypeptide of 33 kD appeared, whereas concomitantly one of 34 kD became barely detectable and finally disappeared as the maturation progressed. During maturation, the synthesis of a 67 kD polypeptide increased and became predominant at the end of the maturation process. The synthesis of actin decreased after 18 hr of culture from a very high to a low level of synthesis.

Timing of Changes in Protein Synthesis Pattern in Elicitor-Treated Cell Suspension Cultures of Parsley ( Petroselinum crispum)

Abstract The timing of changes in the protein synthesis pattern of elicitor-treated, [35S]methionine-labelled parsley cells (Petroselinum crispum) was analyzed by two-dimensional gel electropho­ resis. Five groups were distinguished from a large number of elicitor-responsive as well as un­ responsive proteins. Two groups were synthesized de novo either early or late after elicitor ap­ plication; two other groups were strongly reduced in their rates of synthesis either early or late after elicitor application; and one group was not appreciably affected at all. The elicitor-in-duced changes altered the total protein com position considerably. A few selected, induced pro­ teins were functionally identified. These included two early induced enzymes, phenylalanine amm onia-lyase (PAL) and 4-coum arate:C oA ligase (4C L), and a late induced enzyme, a ber-gaptol O-methyltransferase (BM T) which is specifically involved in the biosynthesis of furano-coumarin phytoalexins. The biological significance of the observed differential timing of changes in protein synthesis rates is discussed.

Changes in protein synthesis and phosphorylation patterns during bovine oocyte maturation in vitro

Sequential protein synthesis and protein phosphorylation patterns were generated by radiolabelling bovine cumulus-oocyte complexes after various periods of culture with [35S]methionine and [32P]orthophosphate respectively. The radiolabelled oocytes were assessed for their nuclear status and used individually for gel electrophoresis. Marked changes in the protein synthesis patterns were observed exclusively after germinal vesicle breakdown (GVBD), whereas oocytes which remained in the germinal vesicle stage showed a consistent protein synthesis pattern. The changes were observed after 8 and 16 h or culture, shortly after GVBD and before first polar body extrusion. From 3 h of culture, dominant phosphoprotein bands with apparent molecular weights of 24,000 and two between 50,000 and 60,000 were observed. The latter bands displayed slight molecular weight changes, which were not closely time related. After GVBD, the phosphoprotein band with Mr 19,000 was no longer observed. This study demonstrates that specific changes in protein synthesis and protein phosphorylation are programmed during bovine oocyte maturation.

Common responses of cultured soybean cells to 2,4-D starvation and fungal elicitor treatment

The patterns of in vivo protein synthesis in soybean cell suspensions were compared by polyacrylamide gel electrophoresis after the cells had been submitted to different stress conditions : treatment with Phytophthora megasperma (Pmg) cell wall elicitors, 2,4-D starvation and heat shock (HS) temperatures. Changes in protein synthesis patterns induced after elicitation of cell suspensions or after infection of soybean hypocotyls by Pmg were found to be similar to changes brought about by auxin starvation of the cells. Changes common to both stress situations involve a prominent 17 kDa peptide family and 27, 29, 35 and about 45 kDa peptides. Moreover, "defense" reactions, i.e. glyceollin accumulation and synthesis of chalcone synthase (CHS) were also strongly stimulated in auxin-starved cells. On the contrary, although characteristic sets of low molecular weight heat shock (HS) proteins were synthesized by cells grown at 37°C, no clear similarity was observed with peptides characteristic of auxin-starved cells.

An analysis of protein synthesis patterns during early embryogenesis of the urodele - Ambystoma mexicanum

Changes in protein synthesis during early Ambystoma mexicanum (axolotl) embryogenesis were monitored using two-dimensional (2-D) polyacrylamide gel electrophoresis. No change in synthesis patterns during progesterone-induced oocyte maturation was detected. In oocytes matured in vivo (unfertilized eggs), however, the synthesis of several oogenetic proteins ceased, only to be resumed later in development. At fertilization, one novel non-oogenetic protein was found. A cleavage-specific protein was also detected. Dramatic changes in protein synthesis patterns were detected at gastrulation in axolotl embryos. About 10% of the proteins synthesized at earlier stages ceased synthesis at gastrulation. Another 10% of the proteins synthesized during gastrulation were novel. A gastrulation-specific protein was also detected. After gastrulation additional novel non-oogenetic proteins were synthesized for most stages examined. A pronounced increase in the number of novel proteins synthesized was observed at the onset of neurulation and during neural fold fusion. Some of those proteins were specific to dorsal or axial structure tissue (AST) and some were specific to ventral or non-axial structure tissue (NAST). Actin and tubulin synthesis was also monitored during axolotl development. While the cytoplasmic gamma- and beta-actins were synthesized at all stages, muscle-specific alpha-actin synthesis began at the head-process stage (stage 23/25).

Effects of low molecular weight nutrients on the pattern of proteins synthesized by non-proliferating murine L cells

When L cells are cultured for prolonged periods of time without a medium change, the rate of synthesis of two polypeptides (82 000 and 95 000 mol. wt) is greatly increased while that of two other polypeptides (85 000 and 56 000 mol. wt) is correspondingly decreased. These changes in protein synthesis pattern were previously shown [1] to be due to depletion of low molecular weight nutrients from the medium. The present study shows that although the medium is severely depleted of glucose and several amino acids, glucose depletion alone is solely responsible for induction of the observed phenomena. Increased synthesis of the 95 000 and 82 000 mol. wt polypeptides has been shown by other investigators to occur in a different cell system under conditions of glucose deprivation. The present study shows that the synthesis of two additional major cytoplasmic proteins, the 85 000 and 56 000 mol. wt polypeptides, is also glucose regulated.

Tubulin synthesis and heat shock-induced cell synchrony in Tetrahymena

This paper offers the suggestion that heat shock inhibition of tubulin synthesis accounts for the molecular mechanism by which periodic heat shocks induce cell synchrony in Tetrahymena. Each heat shock (34 °C) represses tubulin synthesis and blocks the division cycle at the point when the oral structure, rich in microtubules, would normally begin to assemble. Recovery (at 28 °C) from each heat shock is characterized by parallel derepression of tubulin synthesis and of oral development. Changes in protein synthesis patterns are complex when the temperature is shifted up and down between 28 and 34 °C and further experimental support is required in support of the hypothesis here forwarded.