Post on 05-Dec-2014
description
MYXOMYCETESANDZYGOMYCETES
MarilenM.ParungaoBiology112Laboratory
MYXOMYCETES:WHYSTUDYTHEMHERE?
• Membersofthisdivisionarecommonlyreferredtoasslimemolds.
• ClassifiedasPro8sts:sincetheyformamoeboidcells
• RegardedasFungi:becausetheyproducesporesthatareborneinsporangia
MYXOMYCETES
SomeImportantTerms
***allimagesinthenextsetofslidesarefromGoogleimages
PLASMODIUM
• Anakedmul8nucleatemassofprotoplasmthatmovesandfeedsinanamoeboidfashion
• FormedaDernumerousmito8cdivisionofthezygote
MYXAMOEBA
• Anamoeboidcellreleasedbythesporeupongermina8on
• Maycon8nuetoproliferateforanindefiniteperiodof8meifthereisavailablenutrientandtheenvironmentremainsfavorable
• 2func8ons:ingestfoodorfunc8onasgametesduringduringreproduc8on
SWARMCELLS
• Whenfreewaterisavailable,myxamoebaecanbecomeflagellatedandswimthroughthewater
• Duringcondi8onsunfavorableformyxamoebaegrowth,thecellsmayroundupandformtheresistantmicrocyststage
SCLEROTIA
• Ahardres8ngbodyresistanttounfavorablecondi8ons
• Whencondi8onsbecomeunfavorable,aplasmodiumcanbecomedormantformingaresistantstages
• Actuallycomposedofsmallerunitscalledmacrocysts
PHYSARUMTYPICALLIFECYCLE
FRUTINGBODIES
• Frui8ngbodiesmayeitherbecarryingsporesexternallyorinternally
• Exospores:ExampleCera%omyxa– Columnar,branchedstructuresbearsthesporesexternally
FRUITINGSTRUCTURETYPE1:PLASMODIOCARP
• Anelongated,curvedorbranched,vein‐likefrui8ngstructure
• Example:Hemitrichiaserpula– Thesporesandcapilli8umofthissporangiumtyperetainstheshapeoftheplasmodialstage
FRUTINGSTRUCTURETYPE2:SPORANGIUM
• Sac‐likestructure
• Example:PhysarumandDydmium
• thefragile,outerlayerofthesporangiumistheperidiumwhichmaybepersistentordegeneratebythe8methesporangiumisreadytodisperseitsspores
OTHERGENERAFORMINGSPORANGIUM
ArcyriaandStemoni@s
FRUITINGSTRUCTURETYPE3:AETHALIUM
• aethaliumresemblesasessilesporangiumbutismuchlargerandgenerallycushioned– Believedtobefusedsporangium
• Example:– Lycogala=pseudocapilli8umwithoutanydis8nc8veornamenta8onandspores
– Fuligo=producesthelargestknownaethalium
VARIATIONSINCAPILLITIUMMORPHOLOGY
Example:Trichiafavoginea,capilli8umornamentedwithannularrings
Example:Hemitrichiaserpula,capilli8umunbranched.Composedofstrandsofelaters.Elatersornamentedwithdoublespirals,eachcomingfromopposite direc8ons
Example:Lycogalaepidendrum,Capilli8um(actuallypseudocapilli8um)withoutanydis8nc8veornamenta8onandspores
ACRASIN• Chemotac8cchemicalsthatactaspheromonesinaggrega8onofamoebaeincellularslimemolds
• Oneoftheearliestiden8fiedacrasins:cyclicAMPorcAMP– Dictyosteliumdiscoideum– exhibitsacomplexswirling‐pulsa8ngspiralpaUernwhenformingapseudoplasmodium
ZYGOMYCOTA
“thesaprobes,faculta@veparasitesandaircontaminants”
IMPORTANTTERMS
• ZYGOSPORE– Ares8ngsporethatresultsfromthefusionof2gametangia
• ZYGOSPORANGIUM– Asporangiumcontainingazygospore
• ZYGOPHORE– Aspecialhyphacapableofdevelopingintoaprogametangium
DIMORPHICGROWTH• Producingtwomorphologically‐dis8ncttypesofzoospores(yeastformormycelialform)
• Usuallytheyeasttypeoccursinternallyandthemycelialtypeoccursexternally(withexcep8ons)
MUCOR
MucorversusRhizopus
PHYCOMYCES
ABSIDIA
PILOBOLUS
• Uniquesporedispersalmechanism
• “shot‐gunfungi”
SPOREDISPERSAL• Ini8alresulttophototrophicresponseofthesporangiophoreandlateritselonga8on
• Steps:– Sporangiophorebendstowardsthelight(sporangialvesicleactaslens)
– Subsporangialvesiclehashighturgorpressure,uponrupturewillejectthesporangiumtowardsthesourceoflight
hUp://www.chlorofilms.org/index.php/crpVideo/display/videoid/51
DIFFERENCESBETWEENORDERS• ORDERMUCORALES
– Theyhaveawelldevelopedmyceliathatisgenerallyaseptate.Wheneverseptawillbepresent,theylacksporeswithspecializedplugs
• ORDERDIMARGARITALES– TheyaremonotypicunliketheMucorales,theyarehaustorial
mycoparasites
• ORDERKICKXELLALES– Producessingle‐sporesmerosporangia,usuallyfromstructurescalled
pseudophialidesthatareborneonspecializedseptateoraseptatefer8lebranchescalledsporocladia
• ORDERENDOGONALES– Theirsporocarpscontainonlyzygosporesandsporangiaareunknown
DIFFERENCESBETWEENORDERS• ORDERGLOMALES
– TheyarereferredtoasVAMfungiorvesicular‐arbuscularmycorrizaeorendomycorrhizae.Thisgroupmaybefoundin70%ofallplantfamilies
• ORDERENTOMOPHTHORALES– Thisgroupincludestheinsectpathogens
• ORDERZOOPAGALES– TheZoopagalescomprisesthefungalgroupwithinterac8onsthatinvolveavarietyofsmallanimalsandotherfungi,althoughmycoparasi8cspeciesmayalsobeobserved
FORMATIONOFZYGOSPORE
NEXTMEETING:ASCOMYCETES