Developmental Stages of Trypanosomatid Flagellates: a New Terminology

Hoare, Cecil A.; Wallace, F. G.

doi:10.1038/2121385a0

Cited by 242 publications

(157 citation statements)

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“…The proximity of the flagellum basal body and kinetoplast was noted in classical descriptions in the early years of the last century and now forms a definition of the stages of trypanosomatids (Hoare and Wallace, 1966). Traditional fixation techniques showed little structure at the most proximal region of the flagellum basal bodies.…”

Section: Exclusion Zone Filaments Of Tacmentioning

confidence: 99%

“…Early light microscope descriptions of trypanosomes recognized the precise location of the kinetoplast in proximity to the base of the flagellum (Robertson, 1912(Robertson, , 1913. The positions of the flagellum and kinetoplast have become the central features in classifying the different life cycle stages of kinetoplastids (Hoare and Wallace, 1966;Vickerman, 1976). Electron microscopy revealed the kinetoplast to be a highly complex disk-shaped structure located within a distended portion of the mitochondrial matrix adjacent to the flagellum basal bodies (Vickerman, 1973).…”

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confidence: 99%

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A High-OrderTrans-Membrane Structural Linkage Is Responsible for Mitochondrial Genome Positioning and Segregation by Flagellar Basal Bodies in Trypanosomes

Ogbadoyi

Robinson

Gull

2003

MBoC

237

279

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In trypanosomes, the large mitochondrial genome within the kinetoplast is physically connected to the flagellar basal bodies and is segregated by them during cell growth. The structural linkage enabling these phenomena is unknown. We have developed novel extraction/fixation protocols to characterize the links involved in kinetoplast-flagellum attachment and segregation. We show that three specific components comprise a structure that we have termed the tripartite attachment complex (TAC). The TAC involves a set of filaments linking the basal bodies to a zone of differentiated outer and inner mitochondrial membranes and a further set of intramitochondrial filaments linking the inner face of the differentiated membrane zone to the kinetoplast. The TAC and flagellum-kinetoplast DNA connections are sustained throughout the cell cycle and are replicated and remodeled during the periodic kinetoplast DNA S phase. This understanding of the high-order trans-membrane linkage provides an explanation for the spatial position of the trypanosome mitochondrial genome and its mechanism of segregation. Moreover, the architecture of the TAC suggests that it may also function in providing a structural and vectorial role during replication of this catenated mass of mitochondrial DNA. We suggest that this complex may represent an extreme form of a more generally occurring mitochondrion/cytoskeleton interaction. INTRODUCTIONThe African trypanosome Trypanosoma brucei belongs to a large order of pathogenic and free-living flagellated protozoa designated the kinetoplastida. The majority of these organisms possess a single mitochondrion containing a structural mass of proteins and catenated circular DNA molecules, the kinetoplast. The kinetoplast is essential for survival and cyclical transmission of the parasite between mammalian host and tsetse fly. Early light microscope descriptions of trypanosomes recognized the precise location of the kinetoplast in proximity to the base of the flagellum (Robertson, 1912(Robertson, , 1913. The positions of the flagellum and kinetoplast have become the central features in classifying the different life cycle stages of kinetoplastids (Hoare and Wallace, 1966;Vickerman, 1976). Electron microscopy revealed the kinetoplast to be a highly complex disk-shaped structure located within a distended portion of the mitochondrial matrix adjacent to the flagellum basal bodies (Vickerman, 1973). The T. brucei kinetoplast consists of multiple copies of topologically interlocked circular DNA molecules termed maxicircles and minicircles, along with specific kinetoplast proteins. The maxicircle composition of the T. brucei network is 25-50 copies and represents 10% of the network mass (each maxicircle is 20 kb and all have identical DNA sequence). Maxicircles encode the mitochondrial proteins and some guide RNAs (gRNAs), whereas the minicircles are present in several thousand copies (1 kb in length), are heterogeneous in sequence, and encode gRNAs. The gRNAs are essential for the RNA editing process whereby the maxic...

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Section: Exclusion Zone Filaments Of Tacmentioning

confidence: 99%

mentioning

confidence: 99%

A High-OrderTrans-Membrane Structural Linkage Is Responsible for Mitochondrial Genome Positioning and Segregation by Flagellar Basal Bodies in Trypanosomes

Ogbadoyi

Robinson

Gull

2003

MBoC

237

279

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“…The genus Crithidia comprises parasites of insects that were originally characterized by the presence of amastigote and choanomastigote forms in their life cycle (Hoare and Wallace 1966). Cell surface charge of three species of the genus Crithidia was analyzed by determining the cellular electrophoretic mobility, ultrastructural cytochemistry, thin layer and gas liquid chromatography, lectin agglutinations assays and enzymatic treatments.…”

Section: Cellular Electrophoretic Mobilitymentioning

confidence: 99%

The surface charge of trypanosomatids

Souto-Padrón

2002

An. Acad. Bras. Ciênc.

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The surface charge of trypanosomatids was evaluated by means of the binding of cationic particles, as visualized by electron microscopy and by direct measurements of the electrophoretic mobility of cells. The results obtained indicate that most of the trypanosomatids exhibit a negatively charged surface whose value is species specific and varies according to the developmental stages. Sialic acids associated with glycoproteins, glycolipids and phosphate groups are the major components responsible for the net negative surface charge of the trypanosomatids.

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“…Here we describe the effects of antibodies on surface membrane antigens of the amasfigote and promastigote forms (9) of Leishmania enriettii. These include aggregation and distinctive forms of capping with at least temporary loss of antigens from the surface of the parasite.…”

mentioning

confidence: 99%

ANTIBODY-INDUCED MOVEMENT OF MEMBRANE COMPONENTS OF LEISHMANIA ENRIETTII

Doyle

Behin

Mauël

et al. 1974

The Journal of Experimental Medicine

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Protozoal parasites of the genus Leishmania have a unit trilaminar surface membrane (1). Such membranes in mammalian cells are considered to be lipid bilayers in which the integrated membrane proteins are capable of translational diffusion (2). Movement of surface membrane components of mammalian cells into discrete aggregates or a single aggregate, a "cap", has been observed after reaction with ligands such as specific antibody and Concanavalin A (3-8). These aggregates m a y subsequently be endocytosed or shed. Such changes in membrane components m a y constitute the initial step in important phenomena such as antigenic modulation, lymphocyte activation, and immunological tolerance (3-5, 8).Here we describe the effects of antibodies on surface membrane antigens of the amasfigote and promastigote forms (9) of Leishmania enriettii. These include aggregation and distinctive forms of capping with at least temporary loss of antigens from the surface of the parasite. Materials and MethodsParasites.--Viable amastigotes were obtained from infected macrophages by excision and maceration of lesions produced in guinea pigs by intradermal inoculation of L. enriettii 3-6 wk previously (10). Parasites were recovered by centrifugation, washed, and resuspended in Dulbecco's modification of Eagle's medium (11), supplemented with 10% fetal calf serum. Promastigotes were cultured at room temperature in the same medium supplemented with 5% fetal calf serum and 5% of a solution of human hemoglobin (growth medium).Antibodies to Leishmania.--Guinea pigs were infected intradermally with L. enriettii and sera were obtained either during the course of disease (3-6 wk after infection) or after challenge of immune animals with healed lesions. An indirect fluorescent antibody test on formalin-fixed parasites showed antibody titers from 1:54 to 1 : 1,024 in these sera.3,z-globulins isolated from immune sera by DEAE-cellulose chromatography (12) gave similar results to those described for unfractionated sera in immunofluorescence of viable parasites. Immune sera were heated to 56°C for 30 min before use in immunofluorescence.

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Developmental Stages of Trypanosomatid Flagellates: a New Terminology

Cited by 242 publications

References 4 publications

A High-OrderTrans-Membrane Structural Linkage Is Responsible for Mitochondrial Genome Positioning and Segregation by Flagellar Basal Bodies in Trypanosomes

A High-OrderTrans-Membrane Structural Linkage Is Responsible for Mitochondrial Genome Positioning and Segregation by Flagellar Basal Bodies in Trypanosomes

The surface charge of trypanosomatids

ANTIBODY-INDUCED MOVEMENT OF MEMBRANE COMPONENTS OF LEISHMANIA ENRIETTII

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