Lectin activity in mycelial extracts of Fusarium species

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Microbial

Physiology

Lectin

activity

in

mycelial

extracts

of

Fusarium

species

Ranjeeta

Bhari,

Bhawanpreet

Kaur,

Ram

S.

Singh

CarbohydrateandProteinBiotechnologyLaboratory,DepartmentofBiotechnology,PunjabiUniversity,Patiala,Punjab,India

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Received25February2015 Accepted12November2015 Availableonline22April2016 AssociateEditor:RosanaPuccia

Keywords: Fusarium Lectin Hemagglutination Carbohydratespecificity Cultureage

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Lectinsarenon-immunogeniccarbohydrate-recognizingproteinsthatbindtoglycoproteins, glycolipids,orpolysaccharideswithhighaffinityandexhibitremarkableabilityto aggluti-nateerythrocytesandothercells.Inthepresentstudy,tenFusariumspeciespreviouslynot exploredforlectinswerescreenedforthepresenceoflectinactivity.Mycelialextractsof F.fujikuroi,F.beomiformii,F.begoniae,F.nisikadoi,F.anthophilum,F.incarnatum,andF. tabac-inummanifestedagglutinationofrabbiterythrocytes.Neuraminidasetreatmentofrabbit erythrocytesincreasedlectintitersofF.nisikadoiandF.tabacinumextracts,whereasthe pro-teasetreatmentresultedinasignificantdeclineinagglutinationbymostofthelectins. Resultsofhapteninhibitionstudiesdemonstrateduniquecarbohydratespecificityof Fusa-riumlectinstowardO-acetylsialicacids.ActivityofthemajorityofFusariumlectinsexhibited bindingaffinitytod-ribose,l-fucose,d-glucose,l-arabinose,d-mannitol,d-galactosamine hydrochloride, d-galacturonicacid,N-acetyl-d-galactosamine, N-acetyl-neuraminicacid, 2-deoxy-d-ribose,fetuin,asialofetuin,andbovinesubmaxillarymucin.Melibioseand N-glycolylneuraminicaciddidnotinhibittheactivityofanyoftheFusariumlectins.Mycelial extractsofF.begoniae,F.nisikadoi,F.anthophilum,andF.incarnatuminteractedwithmostofthe carbohydratestested.F.fujikuroiandF.anthophilumextractsdisplayedstronginteractionwith starch.Theexpressionoflectinactivityasafunctionofcultureagewasinvestigated.Most speciesdisplayedlectinactivityonthe7thdayofcultivation,anditvariedwithprogressing ofcultureage.

©2016SociedadeBrasileiradeMicrobiologia.PublishedbyElsevierEditoraLtda.Thisis anopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/

licenses/by-nc-nd/4.0/).

Introduction

Lectinsarecarbohydrate-bindingproteinsorglycoproteinsof non-immuneoriginthatplayanimportantroleasrecognition

∗ _{Correspondingauthor.}

E-mail:rssingh11@lycos.com(R.S.Singh).

moleculesincell–cellorcell–matrixinteractions.1_Microbial lectinsincludevariousagglutinins,adhesins,precipitins, tox-ins, and enzymes2 _{and occur widelyin bacteria, protozoa,} viruses, andfungi.3 _{Lectinshaveapplicationsinblood} typ-ingandareknowntoexertessentialfunctionsintheimmune

http://dx.doi.org/10.1016/j.bjm.2016.04.024

1517-8382/©2016SociedadeBrasileiradeMicrobiologia.PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

recognitionprocessofviral,bacteria,mycoplasmal,and par-asiticinfections,aswellasinfertilization,cancermetastasis, andgrowthanddifferentiationseveralcells.4,5 _Afterplants, mushroomsarethemostwidelystudiedgroupoforganisms forlectins,andtheselectinshavegainedconsiderable atten-tionduetotheirpromisingbiologicalactivities.6,7_Yeastlectins areknowntobeinvolvedincell–cellinteractions, pathogene-sis,andcellflocculation.8_{Themitogenicpotentialofmicrobial} lectinshasbeen well establishedas wellastheir abilityto inducemitosisinlymphocytes/splenocytes.9

There are several reports regarding lectins from micro-fungi,includingRhizopusstolonifer,10Aspergillusfumigatus,11,12 A.oryzae,13_{Penicilliummarneffei,}14_{P.thomiiandP.griseofulvum,}15 Sclerotiumrolfsii16_{and Fusariumsolani.}17_{Additionally,} micro-fungiexhibiting lectinactivity and theirpossible functions have been reviewed exhaustively by our group.18 _Singh et al.19–21 _{screened 40 species of Aspergillus for the} pres-ence of lectin activity and discovered wide occurrence of lectins in this genera. Few of them have also been evi-denced to possess mitogenic22–24 _{and immunomodulatory} properties.25

Recently,Singh and Thakur26 _{reported lectinactivity in} mycelialextractsofeightFusariumspecies,namelyF. acumi-natum, F. chlamydosporium, F. compactum, F. crookwellense, F. culmorum,F. dimerum,F. decemcellulare,andF. coeruleum.The present study attempted to explore lectin activity in ten speciesofFusarium,whichhavebeennotinvestigatedearlier. Thelectinswerecharacterizedwithrespecttotheirbiological spectrum and carbohydrate inhibition profile. The expres-sionoflectin activity withrespect tocultureage was also investigated.Thepresentexaminationcouldprovideuseful informationforcataloginglectinsandpromptfurtherresearch onthepossiblerolesandapplicationsofthelectinsisolated fromFusariumsp.

Materials

and

methods

Maintenance,growthandharvestingofmicrobialcultures TenFusariumspecies,namelyF.fujikuroi(MTCC9930),F. beomi-formii(MTCC9946),F.diaminii(MTCC9937),F.annulatum(MTCC 9951), F. begoniae (MTCC 9929), F. nisikadoi (MTCC 9948), F. staphyleae(MTCC9911),F.anthophilum(MTCC10129),F. incar-natum (MTCC 10292), and F. tabacinum (MTCC 10131) were procuredfromMicrobialTypeCultureCollection(MTCC), Insti-tuteofMicrobialTechnology,Chandigarh, India. Allstrains were maintained on potato dextrose agar slants contain-ing potato 20.0%, dextrose2.0%, and agar 2.0%; pH ofthe medium was adjusted to 5.6. Agar slants were stored at 4±1◦C, until further use and were subcultured regularly at an interval of two weeks. The cultures were grown in Erlenmeyer’s flasks (250mL) containing 100mL of mainte-nance medium without agar and were incubated at 25◦C understationaryconditionsfor7and 10days,respectively. Mycelium was harvested by filtration, washed thoroughly with phosphate buffered saline (PBS, 0.1M, pH 7.2), and brieflypressedbetweenthefoldsoffilterpaper.Theculture supernatantwasseparatelycollectedandassayedforlectin activity.

Lectinextraction

ThemyceliumwashomogenizedinPBS(1:1.5,w/v)usingan ultra-highspeedhomogenizer(Ultra-Turrax®_T25basic,

IKA-Werke, Staufen,Germany) and then ground inmortar and pestlewithacidifiedriversandfor30min.19_{Theextractwas} centrifuged(3000×g,20min,4◦C),andthesupernatantwas assayedforlectinactivity.

Hemagglutinationassay

BloodsamplesdrawninAlsever’ssolutionwerestoredat4◦C untilfurtheruse.Erythrocytesuspension(2%,v/v)was pre-paredinPBS,and two-foldseriallydilutedmycelialextract wastestedforagglutinationofhuman,goat,pig,sheep,and rabbiterythrocytes.19_{Thesurfacesofhumanandrabbit} eryth-rocytesweremodifiedwiththeenzymes,neuraminidaseand protease,asdescribedbyMengetal.27_andusedinthe aggluti-nationassay.Hemagglutinationwasdeterminedvisuallybyan appearanceofmatformationasanindicativeoflectinactivity, whereasbuttonformationwastakenasanabsenceoflectin activity.Lectintiterwasdefinedasinverseofthehighest dilu-tioncapableofproducingvisibleagglutinationoferythrocytes. Hapteninhibitionassay

Hapten inhibitionassaywas carriedout againstapanelof carbohydrates according to a method described by Singh etal.19_{Lectinwasincubatedfor1hwithanequalvolumeof} thetestsolutioninthewellsofU-bottommicrotiterplates. Erythrocytesuspensionwasaddedandhemagglutinationwas establishedvisuallyfollowing30minofincubation.Button for-mation in thepresence ofcarbohydrates indicatedspecific interaction, whilemat formation was taken anabsence of interactionbetweenthelectinandthecarbohydrate.The min-imum inhibitoryconcentration(MIC)ofeach ofthespecific carbohydrateswasdeterminedbyserialdoubledilutionofthe testsolution.MICwasdefinedasthelowestconcentrationof thecarbohydratecapableofinducingcompleteinhibitionof lectin-mediatedhemagglutination.

The carbohydrates tested as inhibitors were: d-ribose, l-rhamnose, xylose, l-fucose, d-glucose, d-mannose, d-arabinose, l-arabinose,d-galactose, d-fructose, d-mannitol, d-sucrose, d-maltose, d-lactose, melibiose, d-trehalose dihydrate,d-raffinose,maltotriose,inositol,meso-inositol, d-glucosaminehydrochloride, d-galactosaminehydrochloride, d-glucuronic acid, d-galacturonic acid, N-acetyl-d-glucosamine, N-acetyl-d-galactosamine, 2-deoxy-d-glucose, 2-deoxy-d-ribose,porcinestomachmucin,bovine submaxil-lary mucin, fetuin, asialofetuin, inulin, pullulan, starch, chondroitin-6-sulphate, N-acetyl neuraminic acid, and N-glycolylneuraminicacid.Simplesugarsweretestedatafinal concentrationof100mM,whereasglycoproteinsand polysac-charideswereanalyzedatafinalconcentrationof1mg/mL. Lectinactivityasafunctionofcultureage

Theactivityoflectin-positivecultureswasdetermined asa functionofthemycelialgrowth,asdescribedbySinghetal.28 Erlenmeyer flasks (250mL) containing50mLmedium were

inoculatedwithculturediscs of5mmdiameter(containing myceliumandagar)andincubatedoveraperiodof5–12days at30◦C, under stationary condition. Mycelium was recov-eredat24hintervals,homogenizedinPBS(1:1.5,w/v),and thengroundinmortarandpestlewithacidifiedriversandfor 30min.Lectintiterintheextractswasdetermined.Foreach fungalculture,anidenticalamountofbiomasswasinvariably takeninsamequantityofPBSoverthedaystodeterminethe comparativehemagglutinationasafunctionofcultureage.

Results

Screeningoffungalculturesforthepresenceoflectin activity

Ten species of Fusarium were screened for their ability to agglutinate rabbit, goat, sheep, pig, and human (A, B, AB, andO)erythrocytes.Nolectinactivity inthe culture super-natant was displayed by these Fusarium species, whereas mycelial extracts of seven species, namely F. fujikuroi, F. beomiformii, F. begoniae, F. nisikadoi, F. anthophilum, F. incar-natum, and F. tabacinum were found to agglutinate only rabbit erythrocytes (Table 1); and no agglutination was observed with other erythrocytes. Hemagglutination assay was also performed using neuraminidase and protease-treatedrabbitandhumanerythrocytes.Noneoftheextracts agglutinatedeventhe enzyme-treatedhumanerythrocytes. Agglutination of enzyme-treated rabbit erythrocytes with Fusariumlectinsshowedavariableresponse.Lectinextracts of F. anthophilum exhibited a 4-fold increase in the titer with neuraminidase-treated erythrocytes, whereas that of F. nisikadoi and F. tabacinumshowed onlya 2-fold increase (Fig. 1).However,thetiterofF.incarnatummycelialextracts wassubstantiallyreducedbyneuraminidase-modified eryth-rocytes. Lectin titers of F. fujikuroi, F. beomiformii, and F. begoniae extracts manifested no effect of the treatment withneuraminidaseonerythrocytes.F.fujikuroiandF. tabac-inum extracts displayed titers similar to those of native and protease-treated erythrocytes. The activity of lectins

Table1–LectinactivityofFusariumspp.withrabbit

erythrocytes.

Species Lectinactivity(Titer)

7days 10days F.fujikuroi 0 4 F.beomiformii 8 16 F.begonia 8 16 F.nisikadoi 8 32 F.tabacinum 32 4 F.anthophilum 16 2 F.incarnatum 8 32 F.diaminii 0 0 F.annulatum 0 0 F.staphyleae 0 0

Lectinactivity wasdetermined byhemagglutinationassay. The

mycelialextractswerepreparedfrom7dayand10day-oldcultures.

140

Native erythrocytes

Neuraminidase treated erythrocytes Protease treated erythrocytes

120 100 80

Lectin activity (Titre)

60 40 20 0

F. fujikuroi

F. beomiformii F. begoniae F. nisikadoi F. tabacinumF. anthophilum F. incarnatum

Fig.1–Effectofenzyme-treatmentonagglutinationof rabbiterythrocytesbyFusariumspp.Erythrocyteswere treatedwithprotease(2mg/mL)orneuraminidase (0.2IU/mL)andsuspensionswereusedin hemagglutinationassay.

from other Fusariumspp. wasreduced afterprotease treat-ment.

Carbohydrateinhibitionassay

Carbohydrate specificity profile of Fusarium lectins is pre-sentedinTable2.FewFusariumlectinsdisplayedexceedingly rarecarbohydratespecificities.Lectinactivityofthemajority of Fusarium species was inhibited by d-ribose, l-fucose, d-glucose,l-arabinose,d-mannitol,d-galactosamine hydrochlo-ride,d-galacturonicacid,N-acetyl-d-galactosamine,N-acetyl neuraminicacid,2-deoxy-d-ribose,fetuin,and asialofetuin. F. begoniae, F. anthophilum, and F. incarnatum extracts inter-acted with most of the sugars tested. d-Mannose could slightlyinhibittheactivityofF.nisikadoilectins.d-Galactose andd-trehalosedihydratesuppressedtheactivityofF. bego-niae lectin. Porcine stomach mucin was inhibitory to F. anthophilum and F. begoniae lectins. However, activity of all of the Fusarium lectins was inhibited by bovine submaxil-lary mucin. Melibiose and N-glycolyl neuraminic acid did notsuppress the actionofany ofthelectins. F. fujikuroi,F. beomiformii,andF.tabacinumlectinsinteractedwithonlyfew of the carbohydrates examined. The activity of F. fujikuroi lectinwasinhibitedbyd-galacturonicacid,d-galactosamine hydrochloride,fetuin,andasialofetuinwithrespectiveMICsof 3.12mM,1.56mM,31.25␮g/mL,and250␮g/mL.Thelectinsof F.fujikuroiandF.anthophilumstronglyinteractedwithstarch, and MICs of 1.95␮g/mL and 3.90␮g/mL, respectively, were observed.

LectinactivityofFusariumspp.asafunctionofgrowth Lectinactivitywasdeterminedoveraperiodof5–12daysto determinetheinfluenceofcultureageonlectinexpression. Lectinactivitywasexpressedby7-dayoldculturesofall Fusa-riumlectinsexceptforF. fujikuroi,wherelectinactivity was expressedonlyby9–10daysoldcultures(Fig.2).F.anthophilum andF.tabacinumlectinsdisplayedmaximumactivityafter7–8 daysofcultivation.F.incarnatumexpressedaconsistentlyhigh titerin8–10daysoldcultures.

Table2–CarbohydratespecificityofFusariumspp.lectins.

Carbohydrate F.fujikuroi F.beomiformii F.begoniae F.nisikadoi F.anthophilum F.tabacinum F.incarnatum

d-Ribose – – 25mM 3.12mM 12.5mM 6.25mM 6.25mM l-Rhamnose – – 3.12mM 6.25mM 3.12mM – – Xylose – – 50mM 3.12mM 25mM – – l-Fucose – – 12.5mM 3.12mM 12.5mM – 12.5mM d-Glucose – – 50mM 1.56mM 3.12mM – 3.12mM d-Mannose – – – 25mM – – – d-Arabinose – – – 25mM 12.5mM – 12.5mM l-Arabinose – – 12.5mM 12.5mM 50mM – 50mM d-Galactose – – 12.5mM – – – 50mM d-Fructose – – 1.56mM – – 50mM 12.5mM d-Mannitol – – 3.12mM – 50mM 0.78mM 25mM d-Sucrose – – 12.5mM – 6.25mM – – d-Maltose – – 3.12mM – 1.56mM – – d-Lactose – 3.12mM 50mM – – – – Melibiose – – – – – – – d-Trehalosedehydrate – – 1.56mM – – – – d-Raffinose – – 3.12mM – – 3.12mM 0.78mM Maltotriose – – 12.5mM – 12.5mM – – Inositol – – 12.5mM – – – 12.5mM Meso-inositol – – 6.25mM – – – 25mM d-Glucosamine hydrochloride – – 25mM 6.25mM – – – d-Galactosamine hydrochloride 3.12mM 12.5mM 25mM 12.5mM 6.25mM – 6.25mM d-Glucuronicacid – – 12.5mM – 3.12mM – 25mM d-Galacturonicacid 1.56mM 1.56mM 6.25mM – 50mM – 50mM N-acetyl-d-glucosamine – – 12.5mM 25mM – – – N-acetyl-d-galactosamine – 12.5mM 6.25mM 25mM 12.5mM – 12.5mM 2-Deoxy-d-glucose – – 25mM 12.5mM – 250␮g/mL – 2-Deoxy-d-ribose – – 25mM 125␮g/ml 25mM – 12.5mM

N-acetylneuraminicacid – 12.5mM 0.195mM 12.5mM 3.90mM – –

N-glycolylneuraminicacid – – – – – – –

Bovinesubmaxillarymucin 31.25␮g/mL 0.975␮g/mL 0.06␮g/mL 0.487␮g/mL 0.12␮g/mL 62.5␮g/mL 31.25␮g/mL

Porcinestomachmucin – – 0.975␮g/mL – 0.975␮g/mL – –

Fetuin 125␮g/mL 500␮g/mL 0.243␮g/mL – 0.121␮g/mL 500␮g/mL – Asialofetuin 250␮g/mL 250␮g/mL 0.487␮g/mL 125␮g/mL 0.975␮g/mL – 31.25␮g/mL Chondroitin-6-sulphate – – 500␮g/mL – 15.62␮g/mL – 31.25␮g/mL Inulin – – 125␮g/mL – 125␮g/mL – 500␮g/mL Pullulan – – 500␮g/mL – – 15.62␮g/mL 62.5␮g/mL Starch 1.95␮g/mL – 500␮g/mL – 3.90␮g/mL – –

Note:–,non-inhibitorycarbohydrates.

Simplesugarsweretestedatafinalconcentrationof100mM,whileglycoproteinsandpolysaccharidesweretestedataconcentrationof

1mg/mL.Thetestsolutionswereastwo-foldseriallydilutedacrossthewellsofmicrotiterplatesandincubatedwithappropriatelydiluted

lectintodetermineminimuminhibitoryconcentrationofspecificcarbohydrate.

Discussion

The present study reportslectin activity from seven Fusa-riumspecies,namely,F.fujikuroi,F.beomiformii,F.begoniae,F. nisikadoi, F.anthophilum,F. incarnatum, and F.tabacinum, the presenceoflectinsinthese specieshasnotbeen explored previously.Ourresultsandthoseofpreviousinvestigations conductedbySinghandThakur26_{demonstrateawide} pres-enceofmyceliallectinsinFusariumspecies. Inthepresent study,lectinsfromallthesevenspecieswerefoundto agglu-tinate only rabbit erythrocytes, and no agglutination with human, goat, sheep, and pig erythrocytes was observed. Ishikawaand Oishi29 _{reportedagglutination ofchick, horse} and rabbit erythrocytes by culture filtrate of Fusarium sp., whereasthecellextractwascapableofagglutinatinghuman

erythrocytes. Singh and Thakur26 _{evidenced that Fusarium} lectins mostly agglutinate human and rabbit erythrocytes, and onlyafewofthem couldagglutinate sheep,goat,and porcineerythrocytes.Khanetal.17,30_{foundthatFusariumsolani} lectin agglutinatedonlypronase-or neuraminidase-treated humanerythrocytes.Consideringthesefindings,the hemag-glutination activity ofeach extract wasalso testedagainst neuraminidase-orprotease-treatedhumanerythrocytes,but lectinsfailedtoagglutinateeventheenzyme-modifiedhuman erythrocytes.

Neuraminidase removes sialic acid from the surface of erythrocytes and exposes subterminal galactosyl residues, thus reducing the net negative charge on the surface of erythrocytesandincreasingtheiragglutinationability.31_The decrease inagglutinationoferythrocytes afterthe protease treatmentindicatestheremovalofthepreferredbindingsites

35 F. beomiformii F. begonia F. tabacinum F. nisikadoi F. anthophilum F. incarnatum 30 25 20 15 10

Lectin activity (Titre)

Lectin activity (Titre)

5 0 35 30 25 20 15 10 5 0 5 6 7 8

Culture age (Days)

9 10 11 12

5 6 7 8

Culture age (Days)

9 10 11 12

F. fujikuroi

Fig.2–EffectofcultureageonlectinactivityofFusarium

spp.Themyceliawererecoveredafter24hintervalsovera periodof5–12daysanddisruptedtoassaylectinactivity.

forFusariumlectins.Thetreatmentoferythrocyteswith neu-raminidasewasalsoreportedtoincreasethetitersofFusarium lectins,whereasnosucheffectwasestablishedafterprotease treatments.26

Inthepresentstudy,themajorityoflectinswereinhibited byd-galactosaminehydrochloride,N-acetyl-d-galactosamine, asialofetuin,andfetuin.Mostofthelectinsmanifested inhibi-tionbyfreesialicacid,whichwascontrarytoearlierfindings ofSinghand Thakur.26 _{Khan etal.}30 _{reportedspecificity of} FusariumsolanilectintoN-linkedglycans.Thelectinsinthis studydidnotinteractwithN-glycolylneuraminicacid,which explainsthefailure oflectinstoagglutinate porcine eryth-rocytes.Bovinesubmaxillarymucin isapotentinhibitor of Fusariumlectins,whereasporcinestomachmucinisaweak inhibitor.TheformercontainsN-acetylneuraminicacid, N-glycolylneuraminicacid,N-acetyl9-O-acetylneuraminicacid, and 8,9-di-O-acetyl neuraminic acid. On the other hand, mucin from porcinestomachcontains 90% N-glycolyl neu-raminic acid, 10% N-acetyl neuraminic acid, and traces of N-acetyl 9-O-acetyl neuraminic acid.32 _{Free N-acetyl} neu-raminicacidcouldinhibittheactivityoffewFusariumlectins, butN-glycolylneuraminicacidhadnoinhibitoryeffect,which justifiesthestronginhibitorypotentialofN-acetylneuraminic acidcontainingglycoproteinbovinesubmaxillarymucinand weakbindingwithporcinestomachmucin.Fetuinmainly con-tainsN-glycolylneuraminicacid,33 _{and mostofthelectins} discoveredin representative Fusarium species showed only weakinteractionwithfetuin.Theresultsdepicttheinhibition

oflectinactivityofFusariumextractsbysialoglycoconjugates. However, inhibitionbyasialofetuincorroboratesthe earlier findings,wherelectinsspecificforsialicacidalsomanifested inhibitionbytheasialoformglycoproteins.34,35

Theresultsofthepresentinvestigationsuggestan affin-ityofFusariumlectinstoO-acetylneuraminicacid,whichis alsoreflectedintheerythrocytespecificity.Thelectinsbound torabbiterythrocytes,whichcontainN-O-acetylneuraminic acid. Human A, O, sheep,and goat erythrocytes have sur-faceglycoconjugatesrichinN-acetylneuraminicacid,32_which mighthavebeenresponsibleforthefailureoflectinsto agglu-tinatetheseerythrocytes.However,theaugmentationoflectin titeraftertheneuraminidasetreatmentandthe fine speci-ficityofFusariumlectinscannotbecompletelyexplainedat thispoint.Thesemightbeduetothepresenceofmorethan onelectinintheextractstested.

Fusarium lectins were foundto bedevelopmentally reg-ulated. There was no increase in lectin activity with the progressingcultureageandacorrespondingriseintheprotein contentofmycelia,indicatingthatthelectinactivitywasnot afunctionofgrowthratealone.Thedevelopmentalregulation ofFusariumlectinscorroboratestoearlierreportsonFusarium sp.26_{andothermicrofungi.}15,21,28,36,37

Inthe presentstudy,thelargenumberoflectin-positive speciescapableofagglutinatingonlyrabbiterythrocytes indi-catesahighincidenceofsialicacid-specificlectinsamongst themembersofthisgenus.Althoughhemagglutinating activ-ityisnotapowerfultooltodefineminordifferencesinaffinity betweendifferentmolecules,recognitionofdifferentglycan structuressuggests thewidespreadoccurrenceofreceptors forFusariumlectins.NormaltissueshaveN-acetylneuraminic acid,whereasmalignantcellscontainO-acetyl sialicacid.32 Theselectinscanbeavaluabletoolforlocalizationand assess-mentofglycoconjugatescontainingO-acetylsialicacid.The uniquecarbohydratespecificityofFusariumlectinsinvites fur-therresearchonthisgenus.Thecarbohydratespecificitiesand hemagglutinationprofilesindicatethatmorethanonelectin maybepresentintheextracts.However,furtherinvestigations arerequiredtoestablishthesubtlesaccharidespecificityof Fusariumlectinsreportedherein.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

Acknowledgement

AuthorsarethankfultoHead,DepartmentofBiotechnology, PunjabiUniversity,Patialaforprovidingthenecessary labora-toryfacilitiesduringthewholecourseofthestudy.

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