[Leish-l] Fwd: Re: sandfly, mosquito ..

Thu Apr 9 04:58:29 BRT 2009

I'm sure Jake expected me to rise to the bait in the debate on the terminology of leishmaniae in the sand fly (he knows me well!). After looking at the developmental forms of four species of Leishmania  in different species of sand (space) flies by both the light and electron microscope for over thirty years, it would be surprising if I didn't have an opinion.

One advantage of being an old leishmaniac is that one remembers old work that is seldom cited. (Nowadays anything published more than ten years ago can be safely ignored and, as long as the referee isn't in his dotage, there's a good chance he'll think the paper he's refereeing is original!). 

I remember the pre-mastigote days when we talked about Leishman-Donovan bodies, leptomonads, crithidia etc. Then, in 1966, came the paper by Hoare and Wallace  (Developmental stages of trypansomatid flagellates: a new terminology. Nature,London 212:1385-1386, 1966) putting the case for abandoning these terms (including leptomonad) and replacing them with new words (based on 'mastigote') that made sense and avoided confusion. They were terms for forms of  all trypanosomatids, not just genus Leishmania. This was like a breath of fresh air. But there was then an epidemic of ---mastigotes that John Baker felt was getting out of hand. In 1970, I was inspired to write a poem about this that was distributed to the few dozen workers on leishmaniasis of that time in a short-lived Newsletter on leishmaniasis issued from Jerusalem. It is attached.

            A bit of history. David Molyneux, Dick Ashford and I were the first to see the fine structure of Leishmania with the electron microscope 35 years ago in a paper that is seldom cited (Killick-Kendrick, R., Molyneux, D.H., and Ashford, R.W. Leishmania in phlebotomine sandflies. I. Modifications of the flagellum associated with attachment to the mid-gut and oesophageal valve of the sandfly. Proceedings of the Royal Society,B 187:409-419, 1974.) We adopted the terms nectomonad and haptomonad to describe the promastigotes we saw. That is the origin of the use of these words for stages of Leishmania in the alimentary tract of sand flies - not later publications by other workers. Perhaps this qualifies me to say something about the terminology? We didn't invent these words. The term nectomonad was first used by Minchin & Thompson (1915) and haptomonad by Woodcock (1914). We defined them thus: "We use the term nectomonad for slender promastogotes which are electron-dense, and haptomonad for broad promastogotes which are electron-lucid." We did not define them as dividing or non-dividing, nor did we stipulate where they were or whether they were attached or not. (In fact, the nectomonads were in the abdominal midgut, mostly attached to the microvilli, and the haptomonads were attached to the stomodaeal valve by so-called hemidesmosomes - seen for the first time in this study. ) Later workers have modified the definitions and the terms now mean different things to different people. Hence our current problem. (Whatever we do, I hope the term leptomonad will not gain general acceptance: Hoare and Wallace made a good case for abandoning it as a term to describe the morphology of trypanosomatids.)

            The term metacyclic promastigote was first used to describe slender, non-dividing, unattached promastigotes with a very long flagellum as seen in he probosces of numerous combinations of parasite and vector (see figure in Killick-Kendrick, R. The tranmission of leishmaniasis by the bite of the sandfly. Journal of the Royal Army Medical Corps 132:134-140, 1986.) and shown elegantly by Sacks and colleagues to be the infective forms. (David and I met at the 33rd Annual Meeting of the American Society of Tropical Medicine and Hygiene in  Philadelphia in December 1984 and agreed the term was the right one to describe these forms.)  Later studies by several different workers showed their unique characteristics that enable them to escape destruction by macrophages (reviewed by. Killick-Kendrick, R. The life -cycle of  Leishmania in the sandfly with special reference to the form infective to the vertebrate host. Annales de Parasitologie humaine et comparée 65:37-42, 1990.) The fine structure of a metacyclic promastigote in the proboscis of a sand fly was illustrated by Killick-Kendrick, R., Wallbanks, K.R., Molyneux, D.H., and Lavin, D.R. (The ultrastructure of Leishmania major in the foregut and proboscis of Phlebotomus papatasi. Parasitology Research 74:586-590, 1988.) 

            When Molyneux and I first saw the fine structure of parasites in the pharynx, (Molyneux, D.H., Killick-Kendrick, R., and Ashford, R.W. Leishmania in phlebotomid sandflies. III. The ultrastructure of Leishmania mexicana amazonensis in Lutzomyia longipalpis. Proceedings of the Royal Society,B 190:341-357, 1975) we realised their morphology did not fit the description of promastigotes by Hoare and Wallace. The kinetoplast was not anterior to the nucleus: it was at its side. We did not want to create a new term for these forms, so we adopted paramastigote to describe them (used by other workers before us). (Strangely, the parasites in the pharynx of sand flies are now ignored. Where do they fit?) Later, we saw paramastigotes in electron microscope pictures of Le. braziliensis in the pylorus and hind gut of infected flies (Killick-Kendrick, R., Molyneux, D.H., Hommel, M., Leaney, A.J., and Robertson, E.S. Leishmania in phlebotomid sandflies. V. The nature and significance of infections of the pylorus and ileum of the sandfly by leishmaniae of the braziliensis complex. Proceedings of the Royal Society,B 198:191-199, 1977.) 

            I accept promastigote, nectomonad, haptomonad, metacyclic promastigote and paramastigote. At the moment; I don't feel an urgent need to use other terms.

            I apologise for referring to so many publications that were published before some of you were born! Perhaps they may be of some use when somebody writes the history of Leishmania in the fly!

 Bob K-K

  ----- Original Message ----- 
  From: volf at cesnet.cz 
  To: leish-l at lineu.icb.usp.br 
  Sent: Tuesday, April 07, 2009 10:12 AM
  Subject: [Leish-l] Fwd: Re: sandfly, mosquito ..

  The sequence of forms described by Paul we saw in many parasite-vector
  pairs. However, we try to be more precise as concerns the terminology of
  forms.

  Haptomonad is any form which is attached. Nectomonad is any form which is
  freely moving in the midgut lumen. Therefore one word only is not
  suitable do define the parasite stage. Good terminology of forms was
  invented in 20th century already. Detailed description with all
  measurements are given for example by Walters et al, 1989 and Walters
  1993, and Cihakova and Volf, 1997.

  Very long forms originating from procyclics should be called "Long
  nectomonads". These occur in partially digested bloodmeal and escape to
  ectoperitrophic space of the midgut. Next form prevailing in defecated
  females is short and small. Paul Bates and Mattew Rogers gave them a name
  "Leptomonad", however, it is a synonym of previously used "Short
  promastigotes" or "Short nectomonads" by Walters (and us). Long or short
  nectomonads can attach and become haptomonads.

  In our terminology the sequence of nectomonad forms is:
  Procyclics (oval, short flagellum, within the bloodmeal)
  Long nectomonads (see above)
  Short nectomonads (or leptomonads if you wish)
  Metacyclics (highly motile, with long flagellum, different LPG etc)

  Best wishes
  Petr Volf

  ----- Forwarded message from jacobsr at cc.huji.ac.il -----
      Date: Mon, 06 Apr 2009 12:08:07 +0300
      From: Jake Jacobson <jacobsr at cc.huji.ac.il>
  Reply-To: Jake Jacobson <jacobsr at cc.huji.ac.il>
   Subject: Re: [Leish-l] sandfly, mosquito ..
        To: leish-l at lineu.icb.usp.br

  At 08:56 PM 04/04/09, you wrote:
  >Let's talk about something else!
  >Bob K-K

  I agree - enough is enough already so soon.
  Surely a suitable subject for discussion is the etymology of the
  flagellated forms in the sand fly.
  in the mid-20th Century we changed from Leishman-Donovan bodies to
  amastigotes and leptomonads to promastigotes.
  Now at the beginning of the 21st C we have:
  "The developmental sequence of the five major promastigote forms:
  procyclic promastigotes, nectomonad promastigotes, leptomonad
  promastigotes, haptomonad promastigotes and metacyclic promastigotes.
  The exact position of haptomonad promastigotes in the developmental
  sequence is uncertain". Bates
  PA
  <http://www.sciencedirect.com//science/journal/00207519>International
  Journal for
  Parasitology
  <http://www.sciencedirect.com//science?_ob=PublicationURL&_tockey=%23TOC%235057%232007%23999629989%23662628%23FLA%23&_cdi=5057&_pubType=J&view=c&_auth=y&_acct=C000032999&_version=1&_urlVersion=0&_userid=626711&md5=07330fba5b44fa1b4646d911b337b0f6>Volume
  37, Issue 10, August 2007, Pages 1097-1106.
  Does anyone know whether all these morphs occur in all species in
  their phlebotomine hosts? And is monad the correct suffix for these forms?
  Monad = unity and/or a flagellated protozoan (as of the genus Monas).
  Jake Jacobson

  Dr.R.L.Jacobson MPH PhD
  Department of Parasitology
  The Hebrew University-Hadassah Medical School
  POB 12272, Jerusalem, 91120
  Israel
  Telephone 972-2-6758077
  Fax          972-2-6757425
  Mobile 054-4970731
  NEW:
  VOIP (from USA)  415-963-9801   (up to 17:00hrs EST)
  No amount of experimentation can ever prove me right; a single
  experiment can prove me wrong.
  Albert E.

  ----- End forwarded message -----

------------------------------------------------------------------------------

  At 08:56 PM 04/04/09, you wrote:

    Let's talk about something else!
    Bob K-K

  I agree - enough is enough already so soon.
  Surely a suitable subject for discussion is the etymology of the flagellated forms in the sand fly.
  in the mid-20th Century we changed from Leishman-Donovan bodies to amastigotes and leptomonads to promastigotes.
  Now at the beginning of the 21st C we have:
  "The developmental sequence of the five major promastigote forms: procyclic promastigotes, nectomonad promastigotes, leptomonad promastigotes, haptomonad promastigotes and metacyclic promastigotes. The exact position of haptomonad promastigotes in the developmental sequence is uncertain". Bates PA  International Journal for Parasitology  Volume 37, Issue 10, August 2007, Pages 1097-1106. 
  Does anyone know whether all these morphs occur in all species in their phlebotomine hosts? And is monad the correct suffix for these forms?
  Monad = unity and/or a flagellated protozoan (as of the genus Monas).  
  Jake Jacobson

  Dr.R.L.Jacobson MPH PhD
  Department of Parasitology
  The Hebrew University-Hadassah Medical School
  POB 12272, Jerusalem, 91120
  Israel
  Telephone 972-2-6758077
  Fax          972-2-6757425
  Mobile 054-4970731
  NEW:
  VOIP (from USA)  415-963-9801   (up to 17:00hrs EST)

    No amount of experimentation can ever prove me right; a single experiment can prove me wrong. 
    Albert E. 

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