References of "Goessens, Guy"
     in
Bookmark and Share    
Peer Reviewed
See detailFate of the nucleolar vacuole during resumption of cell cycle in pea cotyledonary buds
Jennane, A.; Thiry, Marc ULg; Diouri, M. et al

in Protoplasma (2000), 210(3-4), 172-178

Meristematic cells of pea cotyledonary buds blocked in G(0-1) state contain a small nucleolus with a large central clear area surrounded by a fibrillar rim. The nucleolar structure varies according to the ... [more ▼]

Meristematic cells of pea cotyledonary buds blocked in G(0-1) state contain a small nucleolus with a large central clear area surrounded by a fibrillar rim. The nucleolar structure varies according to the cell cycle from the G(0-1)-blocked state until the first mitoses occurring between 24 and 27 h after removal of the main stem. In order to better identify and understand the role of the central area in the nucleolar function, its content was investigated by cytochemical and terminal deoxynucleotidyl transferase-immunogold methods. The central area showed the characteristics of a vacuole commonly constituted of the condensed chromatin, ribonucleoprotein granules, and lack of argyrophilic proteins. 3 h alter decapitation, a thickening of the fibrillar rim occurred, accompanied by an increase of granules in the vacuole. After 6 h, the unique vacuole broke up into two to four small vacuoles in which the granules are more abundant. After 12 h the nucleolus acquired compact structure with few minute vacuoles dispersed over the fibrillar component. During the whole cell cycle, the condensed chromatin is always observed in the vacuole. Our findings suggest that the appearance of the vacuoles is subsequent to the output of preribosomes from nucleolus. These vacuoles might play a role in condensation and decondensation of the chromatin. [less ▲]

Detailed reference viewed: 21 (0 ULg)
Peer Reviewed
See detailIdentification of coiled body-like structures in meristematic cells of Pisum sativum cotyledonary buds.
Jennane, A.; Thiry, Marc ULg; Goessens, Guy ULg

in Chromosoma (1999), 108(2), 132-42

This study focused on two types of nuclear bodies visible in plant cells that were previously thought to be similar to the coiled bodies (CBs) of animal cells: the nucleolus-associated body (NAB) and ... [more ▼]

This study focused on two types of nuclear bodies visible in plant cells that were previously thought to be similar to the coiled bodies (CBs) of animal cells: the nucleolus-associated body (NAB) and dense body (DB). We show that both NABs and DBs share common features with animal CBs: they consist of ribonucleoproteins, are silver-stainable, and lack DNA. Immunoelectron microscopy shows that only the NABs are rich in snRNAs and fibrillarin, two markers characteristic of animal CBs. This suggests that NABs rather than DBs are the plant counterparts of the CBs of animal cells. These structures appear most frequently in cells blocked in G0-1, their frequency gradually declining with resumption of the cell cycle and nucleolar activity. During this reactivation period, NABs are released from the nucleolus to the nucleoplasm, suggesting that they may act as nuclear transport or sorting structures. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Peer Reviewed
See detailAgNOR proteins from morphologically intact isolated nucleoli.
Vandelaer, M.; Thiry, Marc ULg; Goessens, Guy ULg

in Life Sciences (1999), 64(22), 2039-47

AgNOR staining has been proposed as a useful tool for the diagnosis and prognosis of cancer. The AgNOR proteins, however, have not yet been clearly identified and characterized, possibly due to the ... [more ▼]

AgNOR staining has been proposed as a useful tool for the diagnosis and prognosis of cancer. The AgNOR proteins, however, have not yet been clearly identified and characterized, possibly due to the partial character of the results obtained when studying the proteins extracted from altered nucleoli isolated by "standard" methods. In the present study, we analysed, on western blots, the AgNOR staining profiles obtained with protein extracts from Ehrlich tumor cell nucleoli isolated by a recent procedure that preserves the nucleolar ultrastructure. In addition to the well-known C23 and B23 protein bands, we readily detected an extra band at approximately 125 Kda. By immunoblotting, we showed that this polypeptide may be related to the nucleolar phosphoprotein pp135 evidenced in rat-cell nucleoli. By immunoelectron microscopy, we detected this protein in the dense fibrillar component and fibrillar center of the nucleoli as well as the coiled bodies. The distribution coincides with the cytochemical AgNOR staining pattern obtained at the ultrastructural level. [less ▲]

Detailed reference viewed: 14 (1 ULg)
Peer Reviewed
See detailUltrastructural nucleolar alterations induced by an ametantrone--poly r(A-U) complex.
Jamison, J. M.; Gilloteaux, J.; Thiry, Marc ULg et al

in Tissue & Cell (1998), 30(4), 475-84

The current study has documented changes in the ultrastructure as well as in the intranucleolar distribution of rDNA and rRNA in RT4 (human transitional cell bladder carcinoma) cell nucleoli following a 3 ... [more ▼]

The current study has documented changes in the ultrastructure as well as in the intranucleolar distribution of rDNA and rRNA in RT4 (human transitional cell bladder carcinoma) cell nucleoli following a 3-h exposure to toxic doses of 50 microM ametantrone (AMT), 200 microM poly (adenylate-uridylate) (poly r(A-U) or an AMT/poly r(A-U) combination with an AMT/polyribonucleotide ratio of 1:4 and a poly r(A-U) concentration of 200 microM. While the main nucleolar components (fibrillar center (F), dense fibrillar component (D), granular component (G) and interstices (I) can be discerned following all treatments, the nucleoli exhibit: compaction, segregation, a decrease in the number of F, an increase in the size of remaining F, margination of intranucleolar chromatin and retention of intranucleolar pre-rRNA and rRNA. The relative abilities of the test agents to induce nucleolar compaction are AMT/poly r(A-U) > poly r(A-U) > AMT > sham-treated, while the abilities of the test agents to induce the remaining nucleolar changes are AMT/poly r(A-U) > or = AMT > poly r(A-U) > sham-treated cells. Poly r(A-U) and the induced interferon induce nucleolar compaction, while AMT produces nucleolar segregation. These results are consistent with a model in which the poly r(A-U) and/or the AMT inhibit DNA transcription and rRNA processing as well as the release of nascent preribosomes from the nucleolus. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Peer Reviewed
See detailUltrastructural distribution of DNA within plant meristematic cell nucleoli during activation and the subsequent inactivation by a cold stress.
Mineur, Pierre ULg; Jennane, A.; Thiry, Marc ULg et al

in Journal of Structural Biology (1998), 123(3), 199-210

We have investigated the precise location of DNA within the meristematic cell nucleolus of Zea mays root cells and Pisum sativum cotyledonary buds, in the course of their activation and induced ... [more ▼]

We have investigated the precise location of DNA within the meristematic cell nucleolus of Zea mays root cells and Pisum sativum cotyledonary buds, in the course of their activation and induced inactivation following a subsequent treatment at low temperature. For this purpose, we combined the acetylation method, providing an excellent distinction between the various nucleolar components, with the in situ terminal deoxynucleotidyl transferase-immunogold technique, a highly sensitive method for detecting DNA at the ultrastructural level. In addition to the presence of DNA in the condensed chromatin associated with the nucleolus, we demonstrated that a significant label was detected in the nucleolus of quiescent cells in both plant models. Evident labels were also found in the dense fibrillar component of actived nucleoli. Whereas in inactivated nucleoli no significant label was observed within the dense fibrillar component, an intense label was seen over the large heterogeneous fibrillar centres only during inactivation. The granular component was never significantly labelled. These results appear to indicate that the DNA present in the dense fibrillar component of activated nucleoli withdraws from this structure during its inactivation and becomes incorporated in the large fibrillar centres. These observations suggest that in plant cells inactivation of rRNA genes is clearly accompanied by changes in the conformation of ribosomal chromatin. [less ▲]

Detailed reference viewed: 81 (2 ULg)
Full Text
Peer Reviewed
See detailReversibility of thiamine deficiency-induced partial necrosis and mitochondrial uncoupling by addition of thiamine to neuroblastoma cell suspensions.
Bettendorff, Lucien ULg; Goessens, Guy ULg; Sluse, Francis ULg

in Molecular and Cellular Biochemistry (1997), 174(1-2), 121-4

Culture of neuroblastoma cells in the presence of low thiamine concentration (16 nM) and of the transport inhibitor amprolium leads to the appearance of signs of necrosis: the chromatin condenses, the ... [more ▼]

Culture of neuroblastoma cells in the presence of low thiamine concentration (16 nM) and of the transport inhibitor amprolium leads to the appearance of signs of necrosis: the chromatin condenses, the oxygen consumption decreases and is uncoupled, the mitochondrial cristae are disorganized, the thiamine diphosphate-dependent dehydrogenase activities are impaired. When 10 microM thiamine are added to these cells, the basal respiration increases, the coupled respiration is restored and mitochondrial morphology is recovered within 1 h. Addition of succinate, which is oxidized via a thiamine diphosphate-independent dehydrogenase, to digitonin-permeabilized cells immediately restores a coupled respiration. Our results suggest that the slowing of the citric acid cycle is the cause of the biochemical lesion induced by severe thiamine deficiency and that part of the mitochondria remain functional. [less ▲]

Detailed reference viewed: 29 (17 ULg)
Peer Reviewed
See detailUltrastructural nucleolar alterations induced by an ametantrone/polyr(A-U) complex.
Thiry, Marc ULg; Jamison, J. M.; Gilloteaux, J. et al

in Experimental Cell Research (1997), 236(1), 275-84

In the present study we examined the ultrastructural modifications as well as the precise distribution of DNA and RNA in RT4 cell nucleoli following a 3-h exposure to nontoxic or toxic doses of ... [more ▼]

In the present study we examined the ultrastructural modifications as well as the precise distribution of DNA and RNA in RT4 cell nucleoli following a 3-h exposure to nontoxic or toxic doses of ametantrone (AMT), poly(adenylate-uridylate) (polyr(A-U), or an AMT/polyr(A-U) combination. While distribution of nucleic acids within the various nucleolar components is not modified following all treatments, the nucleoli exhibit several ultrastructural changes: redistribution of the nucleolar components, decrease in the number of fibrillar centers, and increase in the size of the fibrillar centers. The relative frequencies of the test agents to induce the apparition of nucleoli of compact type are AMT/polyr(A-U) > AMT approximately polyr(A-U) > sham-treated, while the abilities of the test agents to induce the nucleolar segregation are AMT/polyr(A-U) approximately AMT > polyr(A-U) > sham-treated cells. These ultrastructural changes are characteristics of drugs that intercalate into DNA and inhibit rDNA transcription as well as rRNA processing and release of nascent preribosomes from the nucleolus. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailIsolation of nucleoli from ELT cells: a quick new method that preserves morphological integrity and high transcriptional activity.
Vandelaer, M.; Thiry, Marc ULg; Goessens, Guy ULg

in Experimental Cell Research (1996), 228(1), 125-31

We have developed a quick new method for isolating nucleoli which, unlike the methods in current use, preserves the nucleolar ultrastructure. Until now, the isolation process has generally been assumed to ... [more ▼]

We have developed a quick new method for isolating nucleoli which, unlike the methods in current use, preserves the nucleolar ultrastructure. Until now, the isolation process has generally been assumed to empty one of the three major compartments of the nucleolus, the fibrillar center, of its content. We have used the AgNOR staining and in vitro transcription assay to test the degree of structural and functional preservation of the isolated nucleoli. Our results demonstrate the value of our procedure as a reliable tool for biochemical and ultrastructural studies on the nucleolus. Moreover, these proprieties prompt us to investigate the rRNA synthesis, using a nonisotopic approach, within morphologically intact isolated nucleoli. Thus, we show that newly synthesized rRNA transcripts are located not only in the dense fibrillar component, but also indubitably in the fibrillar center. [less ▲]

Detailed reference viewed: 17 (5 ULg)
See detailThe nucleolus during the cell cycle.
Thiry, Marc ULg; Goessens, Guy ULg

Book published by R.G. Landes Company, Chapman and Hall (1996)

Detailed reference viewed: 22 (1 ULg)
Peer Reviewed
See detailLocalization of nucleic acids in hepatocyte nucleoli of rats upon D-galactosamine-induced block of transcription.
Mikhaylova, V. T.; Thiry, Marc ULg; Stephanova, E. et al

in Experimental Cell Research (1996), 225(2), 389-98

The precise localization of DNA and RNA within rat hepatocyte nucleoli during the process of D-galactosamine-induced nucleolar segregation has been studied by using sensitive methods for their detection ... [more ▼]

The precise localization of DNA and RNA within rat hepatocyte nucleoli during the process of D-galactosamine-induced nucleolar segregation has been studied by using sensitive methods for their detection: osmium-ammine staining and terminal deoxynucleotidyl transferase reaction for DNA, and immunoelectron microscopy with anti-RNA antibodies, RNase-gold, and autoradiography with tritiated orotic acid for RNA. The blocking of transcription was followed by the disappearance of intranucleolar condensed chromatin. Agglomerates of thin extended DNA filaments were found to change their location to the nucleolar periphery and to coalesce with each other. At the last stage of nucleolar segregation they were concentrated at the pole of the nucleolar fibrillar remnant while the rest of the nucleolus did not contain any DNA. No DNA was found in the dense fibrillar component of both intact and treated hepatocyte nucleoli. During the process of nucleolar segregation the bulk of the nucleolar RNA was found within the so-called spherical bodies. This RNA appeared to be synthesized shortly before or even after drug administration. The results obtained are in agreement with the hypothesis that the fibrillar centers are the site of nucleolar transcription. They also show that uncompleted molecules of pre-rRNA whose synthesis has been blocked are segregated from the rest of nucleolar RNA species into the spherical bodies. [less ▲]

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailThiamine Deficiency--Induced Partial Necrosis and Mitochondrial Uncoupling in Neuroblastoma Cells Are Rapidly Reversed by Addition of Thiamine
Bettendorff, Lucien ULg; Sluse, Francis ULg; Goessens, Guy ULg et al

in Journal of Neurochemistry (1995), 65(5), 2178-2184

Culture of neuroblastoma cells in a medium of low-thiamine concentration (6 nM) and in the presence of the transport inhibitor amprolium leads to the appearance of overt signs of necrosis; i.e., the ... [more ▼]

Culture of neuroblastoma cells in a medium of low-thiamine concentration (6 nM) and in the presence of the transport inhibitor amprolium leads to the appearance of overt signs of necrosis; i.e., the chromatin condenses in dark patches, the oxygen consumption decreases, mitochondria are uncoupled, and their cristae are disorganized. Glutamate formed from glutamine is no longer oxidized and accumulates, suggesting that the thiamine diphosphate-dependent alpha-ketoglutarate dehydrogenase activity is impaired. When thiamine (10 microM) is added to the cells, the O2 consumption increases, respiratory control is restored, and normal cell and mitochondrial morphology is recovered within 1 h. Succinate, which is oxidized via the thiamine diphosphate-independent succinate dehydrogenase, is also able to restore a normal O2 consumption (with respiratory control) in digitonin-permeabilized thiamine-deficient cells. Our results therefore suggest that the slowing of the citric acid cycle is the main cause of the biochemical lesion induced by thiamine deficiency as observed in Wernicke's encephalopathy. [less ▲]

Detailed reference viewed: 43 (24 ULg)
Full Text
Peer Reviewed
See detailThiamine Deficiency in Cultured Neuroblastoma Cells: Effect on Mitochondrial Function and Peripheral Benzodiazepine Receptors
Bettendorff, Lucien ULg; Goessens, Guy ULg; Sluse, Francis ULg et al

in Journal of Neurochemistry (1995), 64(5), 2013-2021

When neuroblastoma cells were transferred to a medium of low (6 nM) thiamine concentration, a 16-fold decrease in total intracellular thiamine content occurred within 8 days. Respiration and ATP levels ... [more ▼]

When neuroblastoma cells were transferred to a medium of low (6 nM) thiamine concentration, a 16-fold decrease in total intracellular thiamine content occurred within 8 days. Respiration and ATP levels were only slightly affected, but addition of a thiamine transport inhibitor (amprolium) decreased ATP content and increased lactate production. Oxygen consumption became low and insensitive to oligomycin and uncouplers. At least 25% of mitochondria were swollen and electron translucent. Cell mortality increased to 75% within 5 days. [3H]PK 11195, a specific ligand of peripheral benzodiazepine receptors (located in the outer mitochondrial membrane) binds to the cells with high affinity (KD = 1.4 +/- 0.2 nM). Thiamine deficiency leads to an increase in both Bmax and KD. Changes in binding parameters for peripheral benzodiazepine receptors may be related to structural or permeability changes in mitochondrial outer membranes. In addition to the high-affinity (nanomolar range) binding site for peripheral benzodiazepine ligands, there is a low-affinity (micromolar range) saturable binding for PK 11195. At micromolar concentrations, peripheral benzodiazepines inhibit thiamine uptake by the cells. Altogether, our results suggest that impairment of oxidative metabolism, followed by mitochondrial swelling and disorganization of cristae, is the main cause of cell mortality in severely thiamine-deficient neuroblastoma cells. [less ▲]

Detailed reference viewed: 28 (13 ULg)
Peer Reviewed
See detailUltrastructural study of human resting T lymphocytes and Sertoli cells: morphometric and immunocytochemical analysis
Vandelaer, Marc; Thiry, Marc ULg; Goessens, Guy ULg

in Belgian Journal of Zoology (1993), 123

Detailed reference viewed: 13 (0 ULg)
See detailDistribution of nucleic acids in cell nuclei by molecular immunocytochemistry
Thiry, Marc ULg; Vandelaer, Marc; Goessens, Guy ULg

Poster (1993)

Detailed reference viewed: 4 (0 ULg)
See detailUltrastructural distribution of DNA and RNA after D-galactosamine administration in rat liver nucleolar structures
Stephanova, E; Markov, D; Thiry, Marc ULg et al

Conference (1993)

Detailed reference viewed: 9 (0 ULg)
Peer Reviewed
See detailUltrastructural distribution of DNA within the ring-shaped nucleolus of human resting T lymphocytes.
Vandelaer, M.; Thiry, Marc ULg; Goessens, Guy ULg

in Experimental Cell Research (1993), 205(2), 430-2

The precise distribution of DNA within the resting human T lymphocyte nucleolus has been investigated, at the ultrastructural level, by cytochemical and molecular immunocytochemical techniques. The ... [more ▼]

The precise distribution of DNA within the resting human T lymphocyte nucleolus has been investigated, at the ultrastructural level, by cytochemical and molecular immunocytochemical techniques. The nucleolus is partially enveloped by a layer of condensed chromatin which, at several places, penetrates into the nucleolar body until in close contact with the fibrillar centers. Morphometric analysis reveals that 32% of the fibrillar center surface is essentially occupied by condensed chromatin. Using the in situ terminal deoxynucleotidyl transferase-immunogold procedure for detecting DNA, we further show that evident label is exclusively found over the condensed chromatin and over the fibrillar centers, whereas no significant label is detected over the dense fibrillar component of the nucleolus. [less ▲]

Detailed reference viewed: 10 (0 ULg)