Article

In situ hybridization to the Crithidia fasciculata kinetoplast reveals two antipodal sites involved in kinetoplast DNA replication.

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510.
Cell (Impact Factor: 33.12). 09/1992; 70(4):621-9. DOI: 10.1016/0092-8674(92)90431-B
Source: PubMed

ABSTRACT Kinetoplast DNA is a network of interlocked minicircles and maxicircles. In situ hybridization, using probes detected by digital fluorescence microscopy, has clarified the in vivo structure and replication mechanism of the network. The probe recognizes only nicked minicircles. Hybridization reveals prereplication kinetoplasts (with closed minicircles), donut-shaped replicating kinetoplasts (with nicked minicircles on the periphery and closed minicircles in the center), and postreplication kinetoplasts (with nicked minicircles). Replicating kinetoplasts are associated with two peripheral structures containing free minicircle replication intermediates and DNA polymerase. Replication may involve release of closed minicircles from the center of the kinetoplast and their migration to the peripheral structures, replication of the free minicircles therein, and then peripheral reattachment of the progeny minicircles to the kinetoplast.

0 Bookmarks
 · 
54 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Crithidia fasciculata KAP1 gene encodes a small basic protein (p21) associated with kinetoplast DNA. The p21 protein has a nine amino acid cleavable presequence closely related to those of several other proteins targeted to the kinetoplast and binds non-specifically to kinetoplast minicircle DNA. The p21 protein also has a calculated pI of 13 with two amino acids (lysine and alanine) accounting for more than 50% of the residues and with 25 out of 28 lysine residues contained in the C-terminal half of the protein. Immunolocalization of p21 shows that the protein is found exclusively in the kinetoplast with a localization distinctly different from the antipodal localization of kinetoplast DNA topoisomerase and DNA polymerase. The KAP1 gene is a single copy gene and the KAP1 mRNA is present at a constant level throughout the cell cycle. This highly basic protein may play a role in the condensation or segregation of the kinetoplast DNA.
    Molecular and Biochemical Parasitology 07/1998; 94(1):41-52. · 2.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A few hundred ppm of ethylene glycol (a major component in antifreeze) can cause detrimental changes m engine oil. In this work, the a.c. impedance technique has been employed to measure the bulk-layer resistance of engine oil containing glycol. It is found that the bulk-layer resistance declines abruptly as the glycol concentration increases from 50 to 150 ppm. In addition, the bulk-layer resistance for glycol-contaminated engine oil remains constant during a 10-day time span, indicating that the measured resistance is not affected by the formation of micelles between glycol and detergents/dispersants. However, commercial engine oils contain different amounts of detergents, and the bulk-layer resistance for fresh oils varies. Therefore, a software program is necessary to compare the bulk-layer resistance measured from fresh and glycol-contaminated engine oil in order to determine precisely the extent of glycol contamination.
    Sensors and Actuators B Chemical 05/1997; 40(2):193-197. · 3.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Trypanosomatida parasites, such as Trypanosoma and Leishmania, are the cause of deadly diseases in many third world countries. The three dimensional structure of their mitochondrial DNA, known as kinetoplast DNA (kDNA), is unique since it is organized into several thousands of minicircles that are topologically linked. How and why the minicircles form such a network have remained unanswered questions. In our previous work we have presented a model of network formation that hypothesizes that the network is solely driven by the confinement of minicircles. Our model shows that upon confinement a percolation network forms. This network grows into a space filling network, called saturation network, upon further confinement of minicircles. Our model also shows, in agreement with experimental data, that the mean valence of the network (that is, the average number of minicircles topologically linked to any minicircle in the network) grows linearly with minicircle density. In our previous studies however we disregarded DNA flexibility and used rigid minicircles to model DNA, here we address this limitation by allowing minicircles to be flexible. Our numerical results show that the topological characteristics that describe the growth and topology of the minicircle networks have similar values to those observed in the case of rigid minicircles suggesting that these properties are robust and therefore a potentially adequate description of the networks observed in Trypanosomatid parasites.
    Mol. Based Math. Biol. 01/2014; 2:98-106.

Full-text (2 Sources)

Download
1 Download
Available from
Jan 6, 2015