[leish-l] Division of promastigotes

[killickendrick]

Patrick Bastien asks for information on the sequence of the division of organelles of leishmanial promastogotes. Observations on Giemsa-stained smears of L. infantum in the midgut of one of its natural vectors, P.ariasi, show that there appears to be a constant sequence of events. See page 407 in Killick-Kendrick (1979) In Biology of Kinetoplastida vol 2 and the account and figures on pp 126-7 in Molyneux & Killick-Kendrick (1987) in The Leishmaniases in Biology and Medicine, vol 1. 
The sequence is: 
promastogote increases in size and a second basal body appears; 
a daughter flagellum (which stays smaller than the original throughout the process) arises from this second basal body; 
kinetoplast enlarges and stains diffusely - but does not divide yet; 
nucleus enlarges and divides into two equal parts which usually lie side by side, but are sometimes in tandem; 
the kinetoplast, which by now lies across the body, assumes a dumbbell shape and then divides into two equal parts; 
the daughter kinetoplasts, lying just anterior to the nuclei, are small and stain densely with Giemsa's stain; 
the body of the promastigote divides into two equal parts by a cleft that arises between the two flagella and progressively continues posteriorly leaving one nucleus and one kinetoplast in each daughter individual. 
The two new promastigotes are about half the size of the original promastigote and morphologically identical except that the flagellum of one is shorter than that of the other. 
In cultures, the kinetoplast sometimes divides before the nucleus, but I have never seen this sequence in stained smears of any Leishmania species.  
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