Biomedical subjects

Zdenek Hodný

Publications and source records attributed to Zdenek Hodný.

4 recordsLinked to original sources

PubMed2006

Gender differences in behavioural changes induced by latent toxoplasmosis.

There is growing evidence that the protozoan Toxoplasma gondii modifies behaviour of its intermediate hosts, including humans, where it globally infects about 20-60% of the population. Although it is considered asymptomatic in its latent stage, it was previously found to have remarkable and gender different effects on the personality factors A (warmth), G (rule consciousness), L (vigilance, mistrust) and Q3 (self-control, self-image) from Cattell's 16PF Questionnaire. We performed a double blind experiment testing 72 and 142 uninfected men and women, respectively, and 20 and 29 infected men and women, respectively, in order to verify these gender differences using behavioural experiments. Our composite behavioural variables Self-Control and Clothes Tidiness (analogue to the 16PF factors G--conscientiousness and Q3--self-control) showed a significant effect of the toxoplasmosis-gender interaction with infected men scoring significantly lower than uninfected men and a trend in the opposite direction in women. The effect of the toxoplasmosis-gender interaction on our composite behavioural variable Relationships (analogue to factor A--warmth) approached significance; infected men scored significantly lower than uninfected men whereas there was no difference in women. In the composite behavioural variable Mistrust (analogue to factor L), the pattern was affected by environment (rural versus urban). Possible interpretations of the gender differences are discussed.

Adult↗

PubMed2006

Separation of nuclear protein complexes by blue native polyacrylamide gel electrophoresis.

The nucleus is a highly structured organelle with distinct compartmentalization of specific functions. To understand the functions of these nuclear compartments, detailed description of protein complexes which form these structures is of crucial importance. We explored therefore the potential of blue native PAGE (BN-PAGE) method for the separation of nuclear protein complexes. We focused on (i) solubility and stability of nuclear complexes under conditions prerequisite for the separation by BN-PAGE, (ii) improved separation of native nuclear protein complexes using 2-D colorless native/blue native PAGE (CN-/BN-PAGE), and (iii) mass spectrometric analysis of protein complexes which were isolated directly from native 1-D or from 2-D CN/BN-PAGE gels. The suitability of BN-PAGE for nuclear proteomic research is demonstrated by the successful separation of polymerase I and polymerase II complexes, and by mass spectrometric determination of U1 small nuclear ribonucleoprotein particle composition. Moreover, practical advice for sample preparation is provided.

Amino Acid Sequence↗

PubMed2005

The microarchitecture of DNA replication domains.

Most DNA synthesis in HeLa cell nucleus is concentrated in discrete foci. These synthetic sites can be identified by electron microscopy after allowing permeabilized cells to elongate nascent DNA in the presence of biotin-dUTP. Biotin incorporated into nascent DNA can be then immunolabeled with gold particles. Two types of DNA synthetic sites/replication factories can be distinguished at ultrastructural level: (1) electron-dense structures--replication bodies (RB), and (2) focal replication sites with no distinct underlying structure--replication foci (RF). The protein composition of these synthetic sites was studied using double immunogold labeling. We have found that both structures contain (a) proteins involved in DNA replication (DNA polymerase alpha, PCNA), (b) regulators of the cell cycle (cyclin A, cdk2), and (c) RNA processing components like Sm and SS-B/La auto antigens, p80-coilin, hnRNPs A1 and C1/C2. However, at least four regulatory and structural proteins (Cdk1, cyclin B1, PML and lamin B1) differ in their presence in RB and RF. Moreover, in contrast to RF, RB have structural organization. For example, while DNA polymerase alpha, PCNA and hnRNP A1 were diffusely spread throughout RB, hnRNP C1/C2 was found only at the very outside. Surprisingly, RB contained only small amounts of DNA. In conclusion, synthetic sites of both types contain similar but not the same sets of proteins. RB, however, have more developed microarchitecture, apparently with specific functional zones. This data suggest possible differences in genome regions replicated by these two types of replication factories.

Antibodies, Monoclonal↗

PubMed2004

Dynamics of DNA replication: an ultrastructural study.

DNA replication in cells takes place in domains scattered throughout the nucleoplasm. We have characterized the dynamics of DNA synthesis in synchronized mid-S-phase HeLa cells. Saponin-permeabilized cells were allowed to elongate nascent DNA chains in presence of biotin-dUTP for 5, 15, and 30 min (a pulse experiment), or for 5 min followed by an incubation with unlabeled precursors for 10 or 25 min (a pulse-and-chase experiment). The replication foci were then identified in ultrathin sections using immunogold labeling of the incorporated biotin. Total number of particles per nucleus, total scanned area of the nucleus, size, shape, and gold particle number of each labeled cluster, and the density of clusters per nucleus were evaluated. We have demonstrated that as replication proceeds, the labeled sites increase in size up to 240 nm (30 min incorporation) while maintaining a broadly round shape. In pulse-and-chase experiments the labeled DNA was shown to spread to occupy DNA foci of approximately 400 nm in diameter. These results demonstrate that DNA replication is compartmentalized within cell nuclei at the level of DNA foci and support the view that the synthetic centers are spatially constrained while the chromatin loops are dynamic during DNA synthesis.

Binding Sites↗