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

Wed Apr 8 09:03:03 BRT 2009

Dear coleagues,

In my opinion, the most precise, useful and straightforward nomenclature of the Leishmania forms found in sandfly is
from Lawyer et al 1990 (procyclic, nectomonad, haptomonad, paramastigote and metacyclic). “Forms” of parasites can
only be connected with “morphology” seen in the scope and not with functions.  After the dissection and maceration of
infected sandfly guts, all the parasite forms stained by Giemsa can be well defined by Lawyer’s terminology. According
to my observation, independently if they are L. major, L. chagasi, L. braziliensis, L. guianensis, L. amazonensis
infecting distinct vectors as P. papatasi, P. duboscqi, Lu. longipalpis, Lu. migonei, Lu. intermedia and Lu. whtiman,
all the parasite forms can be classified using this terminology.

The only exception in the Lawyer nomenclature is the “metacyclic form” that was named based in vitro cultures of
Leishmania and later it was demonstrated with similar function in sandfly vectors by Sacks & Perkins 1985 (infective
form for vertebrate hosts). Besides, according to my understanding, there is no function determined for all the other
Leishmania forms existent in sandfly vectors. All the information in the literature relating parasite form with
function in the sandfly is speculation and they lack of experimental works. In fact, still is necessary to understand
how these forms differentiate and which ones are involved in the metacyclogenesis inside the sandfly vector. In cell
culture the metacyclogenesis is a phenomenon that does not involve all these forms seen in the vector.

Another point related with Bates remarks: The procyclic forms is present during all the time inside infected flies. It
reasonable to suppose that they are not only precursors of nectomonads. They can be "stem cells" (immature
undifferentiated cell) that can differentiate and proliferate to any Leishmania forms including the metacyclic
dependently of the gut physiology or any inductive factors during the parasite development.

Obs.: Opinions are very good for arguments, but certainly a lot of experimental work still needs to be done for
clarifying several aspects related with functions of the Leishmania forms inside sandfly.

Best,
Paulo Pimenta

On Wed, April 8, 2009 5:59 am, Bates, Paul wrote:
> I would add a couple of points to what Petr has said (if anybody is interested!).
>
>
> My view is that although there are some (undefined) "rules" about using names, in general these are meant to be
> helpful in understanding the underlying biology. If they are useful they will be used, if not they will become
> forgotten and replaced by more useful terms.
>
> Regarding short promastigotes = short nectomonads = leptomonads (in our terminology), the usefulness of this term is
> intended to reflect the different role of this form in life cycle progression (based on our current understanding -
> which could change of course). What distinguishes these forms is that they are dividing (unlike nectomonads), they
> are the precursors of metacyclic promastigotes, they produce promastigote secretory gel, and the major population
> (along with metacyclics) in late stage infections. Giving these forms a different name is (in my view) helpful in
> emphasising their different bioogical properties.
>
> "Haptomonad" should be reserved for attached forms, but only those that develop hemidesmosomal flagellar attachment
> to the foregut, stomodeal valve or hindgut, as these are functionally and morphologically different to attached forms
> on the midgut epithelium i.e. mediated by receptors and ligands (LPG etc.). These latter forms are often nectomonads!
>
>
> More problematic than either of the above is the general misuse of the term procyclic promastigote, often used rather
> loosely to mean anything other than metacyclic promastigotes. We can argue about nomenclature of some of the forms
> above, but it is clear that to lump them all together is a mistake and obscures our thinking. "Procyclic" should be
> reserved for the first stages found in the flies - a rather weakly motile replicating form that are precursors of
> nectomonads.
>
> [On a related issue it has always amused me how exercised people can get over axenic vs. tissue amastigotes, their
> similarities or differences. Definitely an important issue, I agree, but what about "axenic promastigotes", because
> for sure what we grow in our culture flasks is often very different to what we see in sand flies! Cultures tend to be
> a mixture of the replicating forms, procyclics and leptomonads, which of course never occur together in vivo in time
> or space].
>
> For a good review on this topic see Shaden Kanhawi's review in Trends in Parasitology from a few years ago.
>
>
> Paul Bates.
> ________________________________________
> From: leish-l-bounces at lineu.icb.usp.br [leish-l-bounces at lineu.icb.usp.br] On Behalf Of volf at cesnet.cz [volf at cesnet.cz]
>  Sent: 07 April 2009 09:12
> To: leish-l at lineu.icb.usp.br
> 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=07330fba5b44fa1b4646d
> 911b337b0f6>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 -----
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>
> --
> Centro de Pesquisas Rene Rachou/CPqRR - A FIOCRUZ em Minas Gerais.
> Rene Rachou Research Center/CPqRR - The Oswaldo Cruz Foundation in the State of Minas Gerais-Brazil.
>
>
>

-- 
Dr. Paulo F. P. Pimenta, Head
Laboratory of Medical Entomology
Centro de Pesquisas René Rachou
Fundação Oswaldo Cruz - FIOCRUZ
Av. Augusto de Lima, 1715
CEP 30190-002 Belo Horizonte, M.G. Brazil
Phones: 55 31 3349-7735 (secretary)
  55 31 3349-7736 or 3349-7797 (lab)
  55 31 3349-7800 (office)
Fax: 55 31 3295-3115
Cell Phone 55 31 9158-7923

-- 
Centro de Pesquisas Rene Rachou/CPqRR - A FIOCRUZ em Minas Gerais.
Rene Rachou Research Center/CPqRR - The Oswaldo Cruz Foundation in the State of Minas Gerais-Brazil.