RogerJovani Æ LuisaAmoÆ ElenaArriero
OliverKroneÆ AlfonsoMarzal Æ Peter Shurulinkov
GustavoTomasÆ DanielSolÆ Jana Hagen Pilar LopezÆ Jose Martın Æ Carlos Navarro Jordi Torres
Doublegametocyteinfectionsinapicomplexanparasitesofbirds andreptiles
Abstract The simultaneousoccurrenceof maleand femalegametocytesinsideasinglehostbloodcellhas beensuggested toenhanceapicomplexantransmission [’’doublegametocyteinfection(DGI) hypothesis’’].We didabibliographicsearchandadirectscreenofblood smearsfromwildbirdsandreptilestoanswer,forthe firsttime,howcommonaretheseinfectionsinthewild. Takingthesetwoapproachestogether,wereporthere casesofDGIs inPlasmodium, Haemoproteus,Leucocy- tozoonandHepatozoon, andcasesofmale–femaleDGIs inHaemoproteus ofbirdsandreptilesandinLeucocy- tozoonofbirds.Thus,wesuggestthatDGIsandmale–
female DGIs are more widespreadthan previously thought,openinga newresearchavenueon apicom- plexantransmission.
InPlasmodium andrelatedapicomplexanparasites,the occurrenceoftwoormoregametocytesinsideasingle hostbloodcellrecently attractedtheattentionof researchers fortheirpotentialto enhanceparasite transmissionbetweenvertebratehosts(Jovani2002).In thesemicroparasites,transmission occurswhenthe gametocytescontainedinthehostbloodcellsarein- gestedwithinthebloodmealofasuitablevector.Oncein thevector,maleandfemale gametesdifferentiatefrom
maleandfemalegametocytes,respectively,andatleast
R.Jovani()
DepartmentofAppliedBiology,
EstacionBiologicadeDonana(CSIC),Avda.
MariaLuisas/n,41013Sevilla,Spain
E-mail:
Tel.:+34-954-232340
Fax:+34-954-621125
L.AmoÆ E.ArrieroÆ G.TomasÆ P.LopezÆ J.Martın
DepartmentofEvolutionaryEcology,
Museo Nacional deCienciasNaturales(CSIC),
JoseGutierrezAbascal2,28006Madrid,Spain
O.KroneÆ J.Hagen
InstituteforZooand WildlifeResearch,
P.O.Box601103,10252Berlin,Germany
A.MarzalÆ C.Navarro
DepartmentofAnimalBiology,
FacultaddeCiencias,UniversidaddeExtremadura,
06071Badajoz,Spain
P.Shurulinkov
InstituteofZoology,1TzarOsvoboditelBlvd.,
1000Sofia,Bulgaria
D.Sol
DepartmentofBiology,McGillUniversity,
1205avenueDocteurPenfield,Montreal,Quebec,
H3A1B1,Canada
J.Torres
LaboratoryofParasitology,FacultatdeFarmacia,
UniversitatdeBarcelona,Av.JoanXXIIIs/n,
08028Barcelona,Spain
oneofthemobilemalegametesmustsearchforand fertilizeoneoftheimmobilefemalegametescontainedin thesamebloodmeal.Gametocytesarenormallyalone withinsinglehostbloodcells(e.g.erythrocytes),butthey arealsofoundincouples(doublegametocyteinfections, DGIs)orintrios(TGIs)withinagivenbloodcell.
Femalegametesareverysmallcomparedwiththe bloodmealvolumeingestedby the vector; andmale gametesdonotseemtohaveanysearchingmechanism tofindthefemalegamete(Gaillargetal.2003).Thus,it seemslogicalthatsomemechanismoperatingwhilein thevertebrate hostcouldhaveevolvedtoincreasethe proximityofgametocytesandthusgameteswhenonthe bloodmeal;andtwonon-mutually exclusivehypotheses havebeenproposed.Jovani(2002)proposedthatmale– femaleDGIs (i.e.onebloodcellinfectedbyonemale andonefemalegametocyte) mightreducethetime neededformalegametestoencounterfemale gametes, facilitatingparasitetransmission betweenvertebrate hosts.Gaillardetal.(2003)recentlyproposedthatery- throcytesinfectedbygametocytescouldadhereamong theminperipheral hostcapillaries,enhancingthe probabilityofgameteencounter onceinthevector bloodmeal.
The hypothesisproposedbyGaillardetal. (2003) agreeswiththediscoveredpatternofaggregateddistri- butionoferythrocytesinfectedbymalariagametocytes,
Table1 Someexamplesofpublisheddataontheoccurrenceofmultiplegametocyteinfectionsinapicomplexanparasites.DGIDouble gametocyteinfection
HostParasiteObservationReference
ColumbaliviaHaemoproteus columbae
DGIsin17of30hostindividualsinfected, with14–97DGIsineach individualhost
Graczyketal.(1994)
H.columbaeAphotographofamale–femaleDGIBennettand Peirce(1990)
H.columbaeAphotographofamale–femaleDGI, aphotographofaTGI
Mushietal.(1999)
Haemoproteus sppAphotographofafemale–femaleDGITsaietal.(1986)
Geochelone denticulate
H.geochelonisDrawingsandphotographsofmale–female
DGIs;text:‘‘quitecommon’’
occurrenceofDGIs
Lainsonand Naiff (1998)
BirdsHaemoproteus, Plasmodium, Leucocytozoonspp
Drawingsof:immatureDGIsfrom
20Haemoproteus spp,
oneimmatureTGIinH.kairullaevi,
onemale–femaleDGI
inH.bennetti,onemale–maleDGIinH.ortalidum,
twoimmatureDGIsinP.octameriumand P.columbae,
oneimmatureDGIandonemale–femaleDGI
inL.caulleryi
Valkiunas(1997)
Caimanc.crocodilesHepatozoon caimaniPhotographsofDGIsandTGIs, sexunknown
Lainsonetal.(2003)
HomalopsisbuccataHepatozoon sppPhotographofaDGI, sexunknownSalakijetal.(2002)
bothinhumanblood(Gaillardetal.2003)andinthe vectorbloodmeal (Pichonetal.2000).The‘‘DGI hypothesis’’reliesontheassumptionthat DGIs, and especiallymale–femaleDGIs,arewidespreadinnature, butthisiscurrentlyunconfirmed(Jovani 2002).Thegoal ofthisnoteistoshowthatDGIsarewidespreadamong invivoapicomplexanparasitesofwildpopulationsof birdsandreptiles.Moreover,wealsoreporttheoccur- renceofothermultiplegametocyteinfections(MGIs,i.e. morethanonegametocyteinsideasingleerythrocyte), becausethey informusthattheneededprocesstopro- duceaDGIdoesoccurinagivenhost–parasite system, i.e.theentranceand growthintoagivenerythrocyteof morethanonegametocyte.
Wefirstsystematicallysearchedintheparasiteliter- atureforcasesofMGIs.Informationregardingthiskind ofinfectionis littlelikelytoappearinthetitle,abstract, orkeywordsofapublication.Consequently, wewere forcedtosearchourfilesforpapersonapicomplexan infections;andthenweaccurately revisedeachpaperfor anymentionofMGIs. Oursurveyfound anyreference onthepossiblerelevanceofMGIsforanyaspectofthe biology oftheparasite.Indeed, somepapersevencon- tainedphotographsofDGIs, butwithoutanymention inthetext(e.g.Mushietal.1999).Despitethisevident lack ofattentionofresearchersforDGIsandMGIsasa whole,wefoundeightworkswithinformationonDGIs andTGIs(Table1).
Moreover,fromourownbloodsmearcollection,we selectedthosebloodsamplesof11bird andfourreptile speciesinfectedbysomeapicomplexanparasites.These bloodsmearswerecollectedfromwildhostsinGermany andSpainduringtheperiod1996–2002(see Table1).On eachsmear,we activelysearchedforMGIsonaportion equivalenttoca.2,000 erythrocytesforHaemoproteus andHepatozoon infectionsandca.25,000erythrocytes forLeucocytozoon infections,recordingwhenpossible
the sexfor maturegametocytesinvolvedin a MGI. MGIswerefoundinmostoftheparasite–hostassocia- tionsweexamined(Table2).
Moreover,froma parasitesurvey conductedby ShurulinkovandGolemansky(2002,2003),P.S.revised theirownnotestakenduringbloodsmearinspectionina searchforrecordsofMGIs. Althoughnotcomparable withtheothersamplesbecauseitwasnotasystematic searchforMGIs,itisofqualitativeimportanceandalso denotesthelowreportingoftheseinfectionsinpubli- cations,althoughpresentintheresearchers’notes.A totalof15DGIs wererecordedfrom11birdsinfected byHaemoproteus offivebird–parasite assemblages (bird–parasite[numberofbirdswithDGIs, totalnum- berofDGIs]:Sylviaborin–H. belopolskyi[1,3],Lanius minor–H.lanii[2, 2],Laniuscollurio–H.lanii[2,2], Acrocephalusarundinaceus–H.payevskyi[2, 3],Musci- capastriata–H.pallidus[4, 5]).MostoftheseDGIswere constitutedbyfemalegametocytes.However,H. pay- evskyi infectingA. arundinaceus showeda case of a male–femaleDGI. Moreover,twocasesofDGIs were recordedinPlasmodium polare infectingoneindividual ofHirundo rustica. SeeShurulinkovandGolemansky (2002,2003)forthetotalnumbersofspeciesandindi- vidualsexamined.
Ourresultssupporttheviewthat DGIs arewide- spread inavarietyofhost–parasiteassociations, includingPlasmodium, Haemoproteus, andLeucocyto- zooninfectionsofbirdsandHaemoproteus andHepa- tozoon parasitesofreptiles. Moreover,wefound male–femaleDGIs inHaemoproteus parasitesofbirds andreptilesandinLeucocytozoon ofbirds,validating themajor assumptionof the‘‘DGI hypothesis’’.The widespreadoccurrenceof DGIs, and particularlyof male-femaleDGIs, opensa promising directionfor futureresearchon thetransmissionstrategiesof api- complexanparasites.
Table2 OccurrenceofDGIs, male–female(m-f)DGIs,and triplegametocyteinfections (TGIs)inbloodsmears inspectedforthisstudy.
NNumberofinfected individualhostsinspected,or numberofindividualhostswith atleastoneD/TGI. Numbersin
HostCountryNNDGIsNm-fDGIs NTGIs
Haemoproteus parasites
ButeobuteoGermany83(1,1,2)00
FalcotinnunculusGermany30–0
F.subbuteoGermany70–0
TytoalbaSpain41(3)00
BubobuboSpain213(1,2,2)00
parenthesesindicatethe numberofD/TGIsineach
Strix alucoGermany,
Spain
2110(1,2,2,2,3,4,10,11,13,27) 1(1)4(1,1,3,15)
infectedhost.–Sexofparasite couldnotbedetermined
Parus caeruleusSpain4610(1,1,1,1,1,2,2,3,4,6)00
DelichonurbicaSpain577(1,1,1,1,1,1,2)1(1)0
LaniuscollurioSpain110–1(1)
Passer domesticus Spain3911(1,1,1,1,2,2,2,2,2,5,6)4(1,1,1,1) 0
Leucocytozoonparasites
B.buboSpain190–0
AthenenoctuaSpain20–0
Strix alucoSpain50–0
Parus caeruleusSpain152(1,2)–0
Hepatozoon parasites
P.caeruleusSpain90–0
Lacerta lepidaSpain380–0
L.monticolaSpain105 5(1,1,1,2,3)–0
Podarcis muralisSpain280–0
P.hispanicaSpain190–0
AcknowledgementsTheauthors thankJuanA.Fargallo,Jesus Martınez,MariloRomero,AlbertoLizarraga,FranciscoCampos, SantiagoMerino,JuanMoreno,JudithMoralesfortheirfieldwork andJavierCalderaforallowingthecollectionofbloodsmearsat theWildlifeRecuperationCentreof‘‘LosHornos’’.Grantsand funds areasfollows:R.J. (TelefonicaMobilesS.A.), L.A. (C.S.I.C.–Ventorrillo,BOS2002–00598, BOS2002–00547), E.A. (C.S.I.C.–Ventorrillo,07M/0137/2000),A.M.(Juntade Extrema- dura,FIC01A043), G.T. (ResidenciadeEstudiantes;FPI from Comunidad deMadrid,BOS2000–1125, BOS2001–0587). This studyhasbeendoneaccordingtothecurrentlaws ofeachcountry.
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