TheTrehalosetestkitisasimplemethodfortherapidandreliablemeasurementandanalysisoftrehaloseinfoods,beveragesandothermaterials.
Improvementoftolerancetofreeze–thawstressofbaker’syeastbycultivationwithsoypeptides.
Izawa,S.,Ikeda,K.,Takahashi,N.&Inoue,Y.(2007).AppliedMicrobiologyandBiotechnology,75(3),533-537.
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Thetolerancetofreeze–thawstressofyeastcellsiscriticalforfrozen-doughtechnologyinthebakingindustry.Inthisstudy,weexaminedtheeffectsofsoypeptidesonthefreeze–thawstresstoleranceofyeastcells.Wefoundthatthecellsculturedwithsoypeptidesacquiredimprovedtolerancetofreeze–thawstressandretainedhighleaveningabilityindoughafterfrozenstoragefor7days.Thefinalqualityofbreadregardingitsvolumeandtexturewasalsoimprovedbyusingyeastcellsculturedwithsoypeptides.Thesefindingspromotetheutilizationofsoypeptidesasingredientsofculturemediatoimprovethequalityofbaker’syeast.
Starvationresistanceandeffectsofdietonenergyreservesinapredatorygroundbeetle(Merizodussoledadinus;Carabidae)invadingtheKerguelenIslands.
Laparie,M.,Larvor,V.,Frenot,Y.&Renault,D.(2012).ComparativeBiochemistryandPhysiologyPartA:Molecular&IntegrativePhysiology,161(2),122-129.
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Therelationshipbetweennutritionalrequirementsandtheavailabilityorqualityoffoodisaprimeparameterindeterminingthegeographicalexpansionofinvasiveinsects.Atthesub-AntarcticKerguelenIslands,theinvasivegroundbeetleMerizodussoledadinusbecomesthemaininvertebratepredatorwhenitcolonizesnewhabitats,leadingtothelocalextinctionofnativeflyspecies.Suchchangesinthestructureofpreycommunitiesmayaltertheenergymanagement(storageandexpenditure)ofthispredator.Inthisspecies,wemonitoredsurvivalandbodymassduringfooddeprivation,inadditiontoevaluatingtheeffectsoftwodistinctdiets(maggotsversusenchytraeids)ontheconsumptionandrestorationofbodyreserves(sugarsandtriglycerides).Wefoundthatadultscanstarveformorethan60days,andfeedevery3.76daysonaveragewhenfoodisavailable.Werecordedhigherpredationratesonmaggots,associatedwithsteeperbodymassvariations,comparedtoenchytraeids.Sugarsandtriglyceridesweresignificantlyconsumedduringfooddeprivationandrestoredafterrefeeding,butvariedsimilarlyamongindividualssuppliedonthedistinctdiets.Otherparametersmaydeterminethefoodpreferencesobserved,suchassaltcontentinpreytissues,becauseM.soledadinusmainlyfeedsinhypersalineforeshorehabitats,andmaylimittheconsumptionofosmoticconformers.
Freezingtoleranceandlowmolecularweightcryoprotectantsinaninvasiveparasiticfly,thedeerked(Lipoptenacervi).
Nieminen,P.,Paakkonen,T.,Eerilä,H.,Puukka,K.,Riikonen,J.,Lehto,V.P.&Mustonen,A.M.(2012).JournalofExperimentalZoologyPartA:EcologicalGeneticsandPhysiology,317(1),1-8.
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Insectcoldhardinessisoftenmediatedbylowmolecularweightcryoprotectants,suchassugars,polyols,andaminoacids(AA).Whilemanyfree-livingnortherninsectsmustcopewithextendedperiodsoffreezingambienttemperatures(Ta),theectoparasiticdeerkedLipoptenacerviimagocanencountersubfreezingTaonlyduringashortautumnalperiodbetweenhatchingandhostlocation.Subsequently,itbenefitsfromthebodytemperatureofthecervidhostforsurvivalinwinter.Thisstudyinvestigatedthecoldtoleranceofthespeciesbydeterminingitslowerlethaltemperature(100%mortality,LLT100)duringfasterandslowercoldacclimation,bydeterminingthesupercoolingpoint(SCP)andbymeasuringtheconcentrationsofpotentiallowmolecularweightcryoprotectants.TheLLT100ofthedeerkedwasapproximately−16°C,whichwouldenableittosurvivefreezingnighttimeTanotonlyinitscurrentareaofdistributionbutalsofurthernorth.TheSCPwas−7.8°C,clearlyhigherthantheLLT100,indicatingthatthedeerkeddisplaysfreezingtolerance.TheconcentrationsoffreeAA,especiallynonessentialAA,werehigherinthecold-acclimateddeerkedssimilartoseveralotherinsects.Theconcentrationsofprolineincreasedtogetherwithγ-aminobutyrate,arginine,asparagine,cystine,glutamate,glutamine,hydroxylysine,sarcosine,serine,andtaurine.AAcouldbehypothesizedtoactascryoprotectantsby,e.g.,protectingenzymesandlipidmembranesfromdamagecausedbycold.
Anovelsteamedbreadmakingprocessusingsalt‐stressedbaker’syeast.
Yeh,L.T.,Wu,M.L.,Charles,A.L.&Huang,T.C.(2009).InternationalJournalofFoodScience&Technology,44(12),2637-2643.
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Theprocessofapplyingsalt-stressedbaker’syeastduringsouthernstyleChinesesteamedbreaddoughpreparationwasexamined.Baker’syeastwasstressedin7%saltsolutionthenmixedintodough,whichwasthenevaluatedfordoughfermentationproducinggas,doughexpansion,textureprofileanalysis(TPA),colour,specificvolume,spreadratioandsensoryanalysis.Theresultsofthisstudypointedoutsalt-stressedbaker’syeastproducedsignificantamountofgasanddoughexpansion,particularlyafter40minofsaltstressing.Thetextureofsteamedbreadwassofter(463.08g)thancontrol(541.35g)(P<0.05),=""greater=""in=""specific=""volume=""(3.15="">3g-1)thancontrol(2.89cm3g−1)(P<0.05),=""had=""a=""lower=""spread=""ratio=""(1.45)=""than=""control=""(1.74)="">P<0.05)=""and=""a=""significantly=""improved=""sensory=""properties=""for=""taste=""(90.6)=""than=""control=""(81.6)="">P<0.05)=""were=""obtained.="">
Differencesincoldanddroughttoleranceofhigharcticandsub-arcticpopulationsofMegaphoruraarcticaTullberg1876(Onychiuridae:Collembola).
Bahrndorff,S.,Petersen,S.O.,Loeschcke,V.,Overgaard,J.&Holmstrup,M.(2007).Cryobiology,55(3),315-323.
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ThespringtailMegaphoruraarctica(Onychiuridae:Collembola)inhabitsthearcticandsub-arcticpartsofthenorthernhemispherewhereitonaseasonalbasiswillbeexposedtoseverecoldanddesiccatingconditions.InthepresentstudywecomparedhowtraitsofstressresistancedifferedbetweentwopopulationsofM.arcticathatwerecollectedatahigharcticsite(Spitsbergen)andasub-arcticsite(Akureyri,Iceland)withcontrastingthermalenvironments.InadditionweinvestigatedhowcoldanddesiccationaffectedthephospholipidfattyacidcompositionofM.arcticafromSpitsbergen.ThespringtailsfromSpitsbergenwerethemostcoldtolerantandthiswaslinkedtoanalmostthreetimeshigherleveloftrehaloseaccumulationduringcryoprotectivedehydration(15%and5%oftissuedryweightintheSpitsbergenandIcelandpopulations,respectively).AlthoughcryoprotectivedehydrationisintimatelyrelatedtodesiccationstressitwasshownthatM.arcticahadahighermortalitywhendehydratedoverice(−10or−20°C)thanwhendehydratedattemperaturesabove1°C.Thus,survivalwaslowerafterexposureto−10°Cthanafterexposuretoarelativehumidityof91.2%RHat+1°Calthoughbothtreatmentsledtothesamelevelofdehydration.Exposuretobothcold(−10and−20°C)anddesiccationat+1°Ccausedsignificantchangesinthephospholipidfattyacidcompositionwithsomesimilarities.Thesechangesincludedadecreaseinaveragechainlengthofthefattyacidsdueprimarilytoanincreaseinthephospholipidfattyacids16:0andadecreasein18:3and20:4ω6.
TrehalosepromotesthesurvivalofSaccharomycescerevisiaeduringlethalethanolstress,butdoesnotinfluencegrowthundersublethalethanolstress.
Bandara,A.,Fraser,S.,Chambers,P.J.&Stanley,G.A.(2009).FEMSYeastResearch,9(8),1208-1216.
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Trehaloseisknowntoprotectcellsfromvariousenvironmentalassaults;however,itsroleintheethanoltoleranceofSaccharomycescerevisiaeremainscontroversial.Manypreviousstudiesreportcorrelationsbetweentrehaloselevelsandethanoltoleranceacrossavarietyofstrains,yetvariationsingeneticbackgroundmakeitdifficulttoseparatetheimpactoftrehalosefromotherstressresponsefactors.Inthecurrentstudy,investigationswereconductedontheethanoltoleranceofS.cerevisiaeBY4742andBY4742deletionstrains,tsl1Δandnth1Δ,acrossarangeofethanolconcentrations.Itwasfoundthattrehalosedoesplayaroleinethanoltoleranceatlethalethanolconcentrations,butnotatsublethalethanolconcentrations;differencesof20–40%intheintracellulartrehaloseconcentrationdidnotprovideanygrowthadvantageforcellsincubatedinthepresenceofsublethalethanolconcentrations.Itwasspeculatedthattheethanolconcentration-dependentnatureofthetrehaloseeffectsupportsamechanismfortrehaloseinprotectingcellularproteinsfromthedamagingeffectsofethanol.
DivergentstrategiesforadaptationtodesiccationstressintwoDrosophilaspeciesofimmigransgroup.
Parkash,R.,Aggarwal,D.D.,Ranga,P.&Singh,D.(2012).JournalofComparativePhysiologyB,182(6),751-769.
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WaterbalancemechanismshavebeeninvestigatedindesertDrosophilaspeciesofthesubgenusDrosophilafromNorthAmerica,butchangesinmesicspeciesofsubgenusDrosophilafromothercontinentshavereceivedlesserattention.Wefounddivergentstrategiesforcopingwithdesiccationstressintwospeciesofimmigransgroup—D.immigransandD.nasuta.IncontrasttoclinalvariationforbodymelanizationinD.immigrans,cuticularlipidmassshowedapositiveclineinD.nasutaacrossalatitudinaltransect(10°46′–31°43′N).Basedonisofemalelinesvariability,bodymelanizationshowedpositivecorrelationwithdesiccationresistanceinD.immigransbutnotinD.nasuta.TheuseoforganicsolventshassupportedwaterproofingroleofcuticularlipidsinD.nasutabutnotinD.immigrans.Acomparativeanalysisofwaterbudgetofthesetwospeciesshowedthathigherwatercontent,reducedrateofwaterlossandgreaterdehydrationtoleranceconferhigherdesiccationresistanceinD.immigranswhilethereducedrateofwaterlossistheonlypossiblemechanismtoenhancedesiccationtoleranceinD.nasuta.Wefoundthatcarbohydratesactasmetabolicfuelduringdesiccationstressinboththespecies,whereastheirratesofutilizationdiffersignificantlybetweenthesetwospecies.Further,acclimationtodehydrationstressimproveddesiccationresistanceduetoincreaseinthelevelofcarbohydratesinD.immigransbutnotinD.nasuta.Thus,populationsofD.immigransandD.nasutahaveevolveddifferentwaterbalancemechanismsundersharedenvironmentalconditions.MultiplemeasuresofdesiccationresistanceinD.immigransbutreductioninwaterlossinD.nasutaareconsistentwiththeirdifferentlevelsofadaptiveresponsestowetanddryconditionsontheIndiansubcontinent.
Sex-specificdifferencesinthephysiologicalbasisofwaterconservationofDrosophilahydeifromthewesternHimalayas.
Parkash,R.,Singh,D.&Lambhod,C.(2014).CanadianJournalofZoology,92(6),545-555.
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InthecosmopolitanfruitflyDrosophilahydei–Sturtevant1921(Diptera:Drosophilidae),therelativeabundanceofmalesissignificantlyhigherthanfemales,butthephysiologicalbasisofsuchsex-specificdifferencesarelargelyunknown.ForwildpopulationsofD.hydei,wefoundseasonalchanges(summerversusautumn)indesiccationrelatedtraitsbutinallseasonsthedesiccationtoleranceofmaleswashigherthanthatoffemales.Fordesiccationrelatedtraits,wetestedwhetherthermaldevelopmentalacclimationatthreetemperatures(17,21and28°C)matchedseasonalchangesobservedunderwildconditions.Malefliesshowedsignificantlyhighertraitvaluesfordesiccationresistance,cuticularlipidmass,hemolymph,carbohydratecontentanddehydrationtoleranceascomparedwithfemaleswhenrearedatlowerorhighertemperaturesdespitelackofsignificantsex-specificdifferencesinthetotalbodywatercontentoffliesrearedataparticulargrowthtemperature.Weobservedplasticchangesintheamountofcuticularlipidsconsistentwithcorrespondingdifferencesintherateofwaterloss.Treatmentofcuticularsurfacewithorganicsolvent(hexane)supportedtheroleofcuticularlipidsinaffectingtranscuticularwaterloss.WefoundsignificantthermalplasticeffectsfordesiccationrelatedtraitsofD.hydeibutthesexualdimorphismwasintheoppositedirectioni.e.malesweremoredesiccationresistantthanfemalesinD.hydeiwhilethereverseistrueformanyotherDrosophilaspecies(Diptera,Drosophilidae).Ourresultssuggestthatsex-specificdifferencesindesiccationresistancelevelofD.hydeiaregoodpredictorsofrelativeabundancelevelsofmaleandfemalefliesunderwildconditions.
Divergentstrategyforadaptationtodroughtstressintwosiblingspeciesofmontiumspeciessubgroup:DrosophilakikkawaiandDrosophilaleontia.
Ramniwas,S.&Kajla,B.(2012).JournalofInsectPhysiology,58(12),1525-1533.
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Drosophilaleontia(warmadapted)hasbeenconsideredasasisterspeciesofDrosophilakikkawai(sub-cosmopolitan)withaverysimilarmorphology.Wefounddivergentstrategiesforcopingwithdesiccationstressinthesetwospeciesofmontiumsubgroup.Interestingly,incontrasttoclinalvariationforbodymelanizationinD.kikkawai,cuticularlipidmassshowedapositiveclineinD.leontiaacrossalatitudinaltransect.Onthebasisofisofemalelineanalysis,withinpopulationtraitvariabilityincuticularlipidmassperflyispositivelycorrelatedwithdesiccationresistanceandnegativelycorrelatedwithcuticularwaterlossinD.leontia.Acomparativeanalysisofwaterbudgetofthesetwospeciesshowedthathigherabdominalmelanization,reducedrateofwaterlossandgreaterdehydrationtoleranceconferhigherdesiccationresistanceinD.kikkawaiwhilethereducedrateofwaterlossistheonlypossiblemechanismtoenhancedesiccationtoleranceinD.leontia.TheuseoforganicsolventshassupportedwaterproofingroleofcuticularlipidsinD.leontiabutnotinD.kikkawai.Thus,wemaysuggestthatbodymelanizationandcuticularlipidsmayrepresentalternativestrategiesforcopingwithdehydrationstressinmelanicversusnon-melanicdrosophilids.Inboththesespecies,carbohydrateswereutilizedunderdesiccationstressbutahigherlevelofstoredcarbohydrateswasevidentinD.kikkawai.Further,wefoundincreasedesiccationresistanceinD.kikkawaithroughacclimationwhileD.leontialackssucharesponse.Thus,speciesspecificdivergenceinwaterbalancerelatedtraitsinthesespeciesareconsistentwiththeiradaptationstowetanddryhabitats.
RapideffectsofhumidityacclimationonstressresistanceinDrosophilamelanogaster.
Aggarwal,D.D.,Ranga,P.,Kalra,B.,Parkash,R.,Rashkovetsky,E.&Bantis,L.E.(2013).ComparativeBiochemistryandPhysiologyPartA:Molecular&IntegrativePhysiology,166(1),81-90.
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Wetestedthehypothesiswhetherdevelopmentalacclimationatecologicallyrelevanthumidityregimes(40%and75%RH)affectsdesiccationresistanceofpre-adults(3rdinstarlarvae)andadultsofDrosophilamelanogasterMeigen(Diptera:Drosophilidae).Additionally,weuntangledwhetherdrought(40%RH)acclimationaffectscold-toleranceintheadultsofD.melanogaster.Weobservedthatlowhumidity(40%RH)acclimatedindividualssurvivedsignificantlylonger(1.6-fold)underlethallevelsofdesiccationstress(0–5%RH)thantheircounter-replicatesacclimatedat75%RH.Incontrasttoafasterdurationofdevelopmentof1stand2ndinstarlarvae,3rdinstarlarvaeshowedadelayeddevelopmentat40%RHascomparedtotheircounterpartsgrownat75%RH.Rearingtolowhumidityconferredanincreaseinbulkwater,hemolymphcontentanddehydrationtolerance,consistentwithincreaseindesiccationresistanceforreplicatesgrownat40%ascomparedtotheircounterpartsat75%RH.Further,wefoundatrade-offbetweenthelevelsofcarbohydratesandbodylipidreservesat40%and75%RH.Higherlevelsofcarbohydratessustainedlongersurvivalunderdesiccationstressforindividualsdevelopedat40%RHthantheircongenersat75%RH.However,therateofcarbohydrateutilizationdidnotdifferbetweentheindividualsrearedatthesecontrastinghumidityregimes.Interestingly,ourresultsofacceleratedfailuretime(AFT)modelsshowedsubstantialdecreaseddeathratesataseriesoflowtemperatures(0,−2,or−4°C)forreplicatesacclimatedat40%RHascomparedtotheircounter-partsat75%RH.Therefore,ourfindingsindicatethatdevelopmenttolowhumidityconditionsconstrainedonmultiplephysiologicalmechanismsofwater-balance,andconferredcross-tolerancetowardsdesiccationandcoldstressinD.melanogaster.Finally,wesuggestthattheabilityofgeneralistDrosophilaspeciestotoleratefluctuationsinhumiditymightaidintheirexistenceandabundanceunderexpectedchangesinmoisturelevelincourseofglobalclimatechange.
