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J Bonaly

Publications and source records attributed to J Bonaly.

14 recordsLinked to original sources
PubMed2000

In Euglena gracilis, a heat-shock protein related to hsc73 is constitutive and stress inducible.

Using monoclonal antibodies directed against different cytoplasmic isoforms of hsp70 proteins, namely, the constitutive hsc73 and the inducible hsp72 isoforms, we found that one isoform related to hsc73 was present in Euglena gracilis. This hsc73-like protein is expressed with a higher rate of synthesis in cells growing under heat shock than in control cells. Moreover, in cadmium-resistant cells, cultured at normal growth temperature, the rate of synthesis of this protein is constitutively increased. These results indicate that a heat-shock protein related to hsc73 is present in an ancestral eukaryote, Euglena gracilis, and that this protein may be constitutive and stress inducible as well.

Animals↗
PubMed1997

Gene expression of a protein, JB70, related to rat alpha1-acid glycoprotein in Euglena gracilis.

Antibodies directed against rat alpha1-acid glycoprotein (AGP) recognize a 70 kDa antigen, designated JB70, present in extracts of achlorophyllous Euglena gracilis cells as well as in their culture medium. By using 2-dimensional electrophoresis, JB70 appears to be composed of two acidic polypeptides. Additionally, Northern blot analysis reveals the presence in E. gracilis cells of a 2.3 kb mRNA hybridizing with a cDNA probe specific for rat AGP mRNA. Moreover, elevated mRNA levels are detected in dexamethasone-treated E. gracilis cells, indicating a response to this inducer similar to that observed for hepatic AGP. These results strongly suggest that polypeptides closely related to hepatic rat AGP are expressed in E. gracilis cells. They also indicate that, like other gene families implicated in natural defense processes such as heat-shock protein and metallothionein genes, the AGP gene appears to be conserved down to this early diverging eucaryote.

Animals↗
PubMed1997

Immunodetection of a protein related to mammalian arrestin in Euglena gracilis.

Six monoclonal antibodies directed against different epitopes of bovine retinal arrestin recognized a single polypeptide in extracts of achlorophyllous Euglena gracilis cells. This polypeptide had an apparent molecular weight slightly lower: 45kDa vs. 48 kDa, and a more basic isoelectric point compared to that of bovine visual arrestin. It was located in an insoluble cytoplasmic fraction. Immunofluorescence assays show a cytoplasmic punctuated pattern suggesting a cluster distribution or a linkage to some cell structure. The presence of arrestine-like molecules in achlorophyllous Euglena gracilis cells suggests that these proteins might be involved in a peculiar step of chemical signal transduction processes.

Amino Acid Sequence↗
PubMed1996

Different heat-shock proteins are constitutively overexpressed in cadmium and pentachlorophenol adapted Euglena gracilis cells.

To determine whether cellular resistance to a given stressor is related to induction of specific stress-proteins, responses of two adapted Euglena gracilis cell lines, one adapted to cadmium, the other adapted to pentachlorophenol, were analyzed. Our experiments showed that two sets of heat-shock proteins (hsps) were constitutively overexpressed in each cell line: while hsp90, hsp70, hsp55, and hsp40 were induced in cadmium-resistant cells, only hsp40 was induced in pentachlorophenol-adapted cells.

Animals↗
PubMed1995

Protein synthesis in cadmium- and pentachlorophenol-tolerant Euglena gracilis.

This work is a preliminary characterization of two adapted Euglena gracilis cell lines, one to cadmium and the other to pentachlorophenol. Growth curve analyses indicate that tolerance to one pollutant did not protect against the second pollutant. These suggest that metabolic pathways that are induced by one pollutant are specific for this pollutant. This specificity is detectable at the level of gene expression.

Animals↗
PubMed1995

Growth responses of achlorophyllous Euglena gracilis to selected concentrations of cadmium and pentachlorophenol.

The growth response of a wild achlorophyllous Euglena gracilis mutant was studied during exposure to cadmium and pentachlorophenol (PCP). Cadmium gradually reduced the growth rate and terminal cell density; PCP only lengthened the initial lag phase relative to control cultures. Flow cytometry showed that cadmium altered the cell cycle by delaying late S and G2/M phases; PCP did not disturb the cell cycle, but markedly affected DNA staining: the intercalating dyes ethidium bromide and propidium iodide showed little staining compared to controls. However, replication and transcription processes were not altered by PCP, as cell division occurred normally. Cells surviving after PCP treatment apparently developed an adaptative response during the lag phase.

Animals↗
PubMed1994

Cadmium resistance of achlorophyllous Euglena gracilis cells: constitutive overexpression of two heat-shock proteins.

The heat-shock response of Euglena gracilis was studied by cell labeling at both the normal growth temperature (23 degrees C) and an elevated temperature (35 degrees C). Analysis of the labeled proteins by two-dimensional polyacrylamide gel electrophoresis indicated that the rate of synthesis of two polypeptides p55 (55 kDa) and p40 (40 kDa) increased in cells labeled at the highest temperature studied. These polypeptides are also overexpressed in Cadmium-resistant Euglena gracilis cells labeled at the normal growth temperature (23 degrees C). On the basis of these results, p55 and p40 appear to be heat-shock proteins involved in some steps of the acquired Cd-resistance process in Euglena gracilis cells.

Animals↗
PubMed1987

A flow cytometric study of DNA staining in situ in exponentially growing and stationary Euglena gracilis.

DNA stainability by different fluorochromes has been compared in exponentially dividing and stationary Euglena cells. With the intercalating fluorochromes, ethidium bromide, acridine orange and DAPI, a decrease of fluorescence intensity of the G1 cells is observed when cells enter stationary stage. However this decrease of fluorescence is not obtained with the nonintercalating fluorochrome Hoechst 33258. If nuclear basic proteins are extracted, however, the intensity of staining by either Hoechst 33258 or ethidium-bromide is comparable in stationary and dividing cells. Therefore, the decrease of fluorescence intensity of the G1 cells observed during the transition from exponential to stationary phase is not due to a loss of DNA but is related to the exposure of chromatin binding sites for ethidium bromide. In Euglena cells, DNA accessibility for intercalating fluorochromes depends upon chromatin structure and consequently upon cell age.

Acridine Orange↗
PubMed1986

Cadmium-induced ultrastructural changes in Euglena cells.

The ultrastructure of Euglena gracilis grown in the presence of Cd showed only numerous myelin-like structures in mitochondria, chloroplasts altered in shape, and thylakoid arrangement and increase of osmiophilic plastoglobuli. These alterations indicate that respiratory processes are the initial target of Cd toxicity.

Animals↗
PubMed1981

Flow fluorometric study of DNA content in nonproliferative Euglena gracilis cells and during proliferation.

Ethanol-fixed Euglena gracilis cells have been analyzed by flow microfluorometry during the lag, logarithmic and stationary phases. The histogram of a plateau stage culture reveals, as expected, an unimodal distribution, but the peak is at lower fluorescence intensity as compared to G1 logarithmic cells. The fluorescence intensity drops as the cells enter the stationary stage. Ultimately the decrease represents a change of about 25%. When cells recover from the plateau stage, the fluorescence intensity increases during the lag phase, and climbs to the level found in a G1 logarithmic population. The reason for the decrease in the fluorescence intensity during the stationary stage may be due to a possible loss of DNA or to a decrease in the number of chromatin-binding sites for intercalating ethidium bromide.

DNA↗