The Riboflavin Requirement and the Effects of Acriflavin on the Fine Structure of the Kinetoplast of Leishmania tarentolae*

Abstract

SYNOPSIS. Leishmania tarentolae requires at least 10 mμg riboflavin per ml for optimal growth on successive subculture in a denned medium. At this level many organisms are aflagellate or with a short flagellum; higher concentrations of riboflavin did not increase the yield of leptomonads but did increase the proportion with a flagellum at least as long as the body. At limiting levels of riboflavin, acriflavin markedly inhibited growth without producing akinetoplastic forms. With riboflavin at 20 mμ/ml or higher, acriflavin at around 500 mμg/ml permitted an approximately 10‐fold multiplication. Seventy % of the leptomonads formed were akinetoplastic and they could not give rise to subcultures. In electron micrographs of acriflavin‐treated organisms the nucleus was unaffected but the cytoplasmic organelles, notably the kinetoplast and mitochondria, were altered. The mitochondria appeared swollen with their cristae replaced by circular profiles. In the kinetoplast the dense fibrillar material (probably DNA) lost its structure, became diffuse, and eventually disappeared. The observed changes again indicate close relationship between the kinetoplast and the mitochondria of hemoflagellates.

Unveiling the effects of berenil, a DNA-binding drug, on Trypanosoma cruzi: implications for kDNA ultrastructure and replication

“…According to Trager and Rudzinska (1964), parasites are considered dyskinetoplastic (DK) when Giemsa staining of the kinetoplast is no longer detectable and the kDNA appears altered by transmission electron microscopy. In the present work, we suggest that the ultrastructural alterations of kDNA promoted by berenil are related to cell growth inhibition and minicircle replication impairment, which culminate in the generation of DK parasites.…”

ACRIFLAVIN RESISTANCE IN THE HEMOFLAGELLATE, LEISHMANIA TARENTOLAE

“…As described in L . tarentolae (Trager and Rudzinska, 1964) and in Saccharomyces cerevisiae (Yotsuyanagi, 1962 a, b), cristae were dilated or elongated until they appeared as long strands (Figs. 9 and 10) .…”

“…The fine structure of L . tarentolae was described by Trager and Rudzinska (1964) and by . Of particular interest here were the mitochondrion and kinetoplast (Figs .…”

“…Van Assel, 1967 ;Simpson, 1968 ;Hill and Anderson, 1969 ;Strauss, 1971 b) . The loss of the kinetoplast is usually termed dyskinetoplasia (Trager and Rudzinska, 1964 ;see Figs. I and 2) .…”

“…In hemoflagellates it causes the kinetoplast' to disappear (Miihlpfordt, 1964 ;Trager and Rudzinska, 1964 ;Cosgrove, 1966 ; ' The kinetoplast of hemoflagellates is that area of the mitochondrion containing the mitochondrial DNA (K-DNA) . K-DNA comprises about 20 0]0 of the cell's DNA and can be seen in Giemsa-or Feulgen-stained preparations as a dense body at the base of the flagellum.…”