The Ultrastructure of Leishmania donovani

Chang, Patricia C. H.

doi:10.2307/3274723

Cited by 36 publications

(6 citation statements)

References 12 publications

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“…Avian trypanosomes can be readily cultivated on several media, including NNN medium and the SNB-9 (saline-neopeptone-blood) medium described by Diamond and Herman (1954). (Chang, 1956;Pyne and Chakraborty, 1958). The leptomonad forms in culture and in the invertebrate host are spindle-shaped, 14 to 20 |i long and 1.…”

Section: Trypanosomes Of Birdsmentioning

confidence: 99%

Protozoan parasites of domestic animals and of man

Levine¹

1961

518

493

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A disease which is common to man and lower animals is known as a zoo)iosis. Zoonoses were redefined in 1958 by the Joint WHO FAO Expert Committee on Zoonoses as "those diseases and infections which are naturally transmitted between vertebrate animals and man" (World Health Organization, 1959). Less than 20 years ago it was said that there were 50 zoonoses, but in the above report the World Health Organization listed more in connection with vector-borne diseases, altho it need not be restricted to them. epidemiology, taxonomy, evolution, etc.(see ). A dei)ie is a natural population within a species. It lies more or less below the subspecies level, but it is not a formal taxon and is not given a Latin name. There are different types of deme. Nosodemes differ in their clinical manifestations. One example is Leishmania donovani, which has five nosodemes, Indian, Mediterranean, Sudanese, Chinese and South American, which produce different types of disease. Serodemes differ serologically. These are best known among the bacteria and viruses, but also occur among the animal parasites. Tritrichonionas foetus, for example, has several serological types or serodemes. were markedly resistant to infection with Ostertagia circunicincta. while Rambouillets were less so and Southdowns, Shropshires and Hampshires were least resistant.Certain individuals among the more susceptible breeds, however, were just as resistant as the Romneys. Whitlock(1958) has studied genetic resistance to trichostrongylidosis in sheep in some detail.The nutritional status of the host may affect its resistance. Poorly nourished animals are usually more susceptible to infection and suffer more severely from its effects.Protein depletion or protein starvation is particularly important. Lack of specific vitamins and minerals generally decreases resistance, but there are cases in which lack of a certain vitamin which the parasite requires may affect the parasite adversely. Thus, Becker and Smith (1942) found that when calcium pantothenate was added to a ration containing restricted vitamins B,, Bg and pantothenate, the number of oocysts produced hy Einteria nieschulzi infections in the rat was increased.

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Section: Trypanosomes Of Birdsmentioning

confidence: 99%

Protozoan parasites of domestic animals and of man

Levine¹

1961

518

493

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“…The fibrils remain throughout transformation and are present also in leptomonads, where they were first described by Lofgren( 23). Different opinions have been expressed as to the presence of fibrils and number of membranes in Leishmania( 8,9,33,36). Fibrils occur in other species of the family Trypanosomatidae ( 26,45,56) and also in Bodonidae Flagellum.…”

Section: Observations Leishmania Donovani Within Spleen Cellsmentioning

confidence: 99%

The Fine Structure of Leishmania donovani and the Role of the Kinetoplast in the Leishmania‐Leptomonad Transformation*

Rudzinska¹,

D'Alesandro²,

Trager³

1964

The Journal of Protozoology

123

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SYNOPSIS. An electron microscope study of Leishmania donovani revealed major differences between the intracellular leishmanial and the extracellular leptomonad stages. Parasites were also removed from infected hamster spleen, inoculated into cultures, and examined at intervals during incubation in order to follow changes during the transformation from one stage to the other. Prominent changes are evident primarily in the kinetoplast and the nucleoli after several hours of cultivation when the parasite is in an intermediate stage of transition. The kinetoplast, a composite organelk containing DNA and cristae mitochondriales, is a regular, sausage‐like structure in the leishmanial stage, but becomes irregular and enlarges extensively after a few hours in vitro, developing branches that are mitochondrial in nature and which, very likely, become new mitochondria. In the nucleus, significant nucleolar changes occur. The two homogeneous nucleoli characteristic of the leishmanial stage merge during transformation into one which is larger, less compact, and composed of small centrally located granules about 100 Å in diameter and larger particles over 200 Å in diameter at the periphery. These transformations of the kinetoplast and nucleolus are undoubtedly expressions of adaptive changes in the metabolic pattern of an intracellular parasite transferred to a markedly different extracellular environment of much lower temperature. It was also found that the leishmanial stage of the parasite has two unit membranes which extend over the flagellum and the flagellar pocket; the intermediate stage and the leptomonad have only a single membrane. Furthermore, some leishmanias in spleen cells were found to be covered by a capsule‐like structure formed by the deposition of fine granular material between the two unit membranes. Since two to four organisms were occasionally found within such capsules, it is possible that encapsulation is a preparatory step for reproduction.

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“…The cell body membrane, flagellum, nucleus, mitochondrion with kinetoplast, Golgi, contractile vacuole, paraflagellar rod, lipid bodies, acidocalcisomes and glycosomes were segmented for each individual whole cell ( Fig 1A and 1B , S1 and S2 Movies). Organelles were identified as per previous descriptions in transmission electron microscopy [ 14 , 19 , 20 ]. The volume and surface area was calculated from the segmentation of each cellular structure and organelle and counts were made of multi-copy organelles, shown below and in S1 Table .…”

Section: Resultsmentioning

confidence: 99%

Whole cell reconstructions of Leishmania mexicana through the cell cycle

Hair,

Yanase,

Moreira-Leite

et al. 2024

PLoS Pathog

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The unicellular parasite Leishmania has a precisely defined cell architecture that is inherited by each subsequent generation, requiring a highly coordinated pattern of duplication and segregation of organelles and cytoskeletal structures. A framework of nuclear division and morphological changes is known from light microscopy, yet this has limited resolution and the intrinsic organisation of organelles within the cell body and their manner of duplication and inheritance is unknown. Using volume electron microscopy approaches, we have produced three-dimensional reconstructions of different promastigote cell cycle stages to give a spatial and quantitative overview of organelle positioning, division and inheritance. The first morphological indications seen in our dataset that a new cell cycle had begun were the assembly of a new flagellum, the duplication of the contractile vacuole and the increase in volume of the nucleus and kinetoplast. We showed that the progression of the cytokinesis furrow created a specific pattern of membrane indentations, while our analysis of sub-pellicular microtubule organisation indicated that there is likely a preferred site of new microtubule insertion. The daughter cells retained these indentations in their cell body for a period post-abscission. By comparing cultured and sand fly derived promastigotes, we found an increase in the number and overall volume of lipid droplets in the promastigotes from the sand fly, reflecting a change in their metabolism to ensure transmissibility to the mammalian host. Our insights into the cell cycle mechanics of Leishmania will support future molecular cell biology analyses of these parasites.

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The Ultrastructure of Leishmania donovani

Cited by 36 publications

References 12 publications

Protozoan parasites of domestic animals and of man

Protozoan parasites of domestic animals and of man

The Fine Structure of Leishmania donovani and the Role of the Kinetoplast in the Leishmania‐Leptomonad Transformation*

Whole cell reconstructions of Leishmania mexicana through the cell cycle

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