Division of Comparative Physiology and Biochemistry, Society for Integrative and Comparative Biology
Total Page:16
File Type:pdf, Size:1020Kb
Division of Comparative Physiology and Biochemistry, Society for Integrative and Comparative Biology Cold-Shock Injury and Rapid Cold Hardening in the Flesh Fly Sarcophaga crassipalpis Author(s): Cheng-Ping Chen, David L. Denlinger and Richard E. Lee Jr. Source: Physiological Zoology, Vol. 60, No. 3 (May - Jun., 1987), pp. 297-304 Published by: University of Chicago Press . Sponsored by the Division of Comparative Physiology and Biochemistry, Society for Integrative and Comparative Biology Stable URL: http://www.jstor.org/stable/30162282 Accessed: 25-02-2016 14:44 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Division of Comparative Physiology and Biochemistry, Society for Integrative and Comparative Biology and University of Chicago Press are collaborating with JSTOR to digitize, preserve and extend access to Physiological Zoology. http://www.jstor.org This content downloaded from 134.53.236.18 on Thu, 25 Feb 2016 14:44:30 UTC All use subject to JSTOR Terms and Conditions COLD-SHOCKINJURY AND RAPIDCOLD HARDENING IN THE FLESHFLY SARCOPHAGACRASSIPALPIS' CHENG-PINGCHEN,2 DAVID L. DENLINGER,2AND RICHARD E. LEE,JR.3 Departmentof Entomology,Ohio State University, Columbus, Ohio 43210; and Department of Zoology, MiamiUniversity at Hamilton,Hamilton, Ohio 45011 (Accepted9/16/86) Directexposure to -10 C, in the absenceof tissue freezing,causes high mortality in Sarcophagacrassipalpis: this result suggests that injury is due to coldshock. However, briefacclimation at 0 C enableslarvae, pupae, and pharateadults of Sarcophaga crassipalpisto survive-10 C. Chillingfor as shorta periodas 10 min enabled50% of the flies to survivea 2-h exposureto -10 C. Enhancementof cold tolerancewas linearover the firsthour of chillingat 0 C. Theoptimal temperature range eliciting the rapidacclimation response was 6-0 C, butthe effect could also be stimulatedby hightemperature (36 C). The rapid increase in coldtolerance correlates with concom- itantincreases in hemolymphosmolality and glycerol levels. This response suggests a novelrole for glycerol in protectinginsects against injury resulting from cold shock, althoughother unidentified mechanisms may be involvedin thisresponse. That both nondiapause-and diapause-programmedflies respond to short-termchilling indicates that this rapidresponse is not partof the diapausesyndrome but probablyfunctions in eithertype of fly as an adaptationto survivebrief periods of low temperature. INTRODUCTION causing injury in cells during freezing Cold shock is a form of cellularinjury (McGrath1985). Studies observedimmediately after rapid cooling of cold hardeningin insectshave but in the absenceof ice formationin ex- generallyfocused on cold tolerance and tracellularfluids (Morris et al. 1983). This survivalabove and below the temperature phenomenonis also referredto as thermal at which spontaneousnucleation of body water shock or direct-chillinginjury. Cold shock occurs, termed "the supercooling is distinct from indirect-chillinginjury, point (SCP)"(Baust and Lee 1982). Based on this criterion,a speciesis as which occurs after long-termexposure-- categorized daysor weeks-to low temperatures(Levitt freeze-tolerantor freeze-intolerant.The 1980). The extent of cold-shockinjury in- cold-hardening process may include creaseswith higherrates of coolingand the changes in whole-body SCPs, the accu- absolutelimit of low-temperatureexposure. mulation of low molecularweight polyols Althoughnot generallyaccepted as a wide- and sugars,and the synthesisof thermal spreadcellular response to chilling,recently hysteresisfactors and ice-nucleatingagents it has been arguedthat cold shock may be (see reviewsby Baust 1981; Duman and a significant, but unrecognized, factor Horwath 1982; Zachariassen1985). To study the dynamicsof the cold-hardening process,most investigatorshave used rel- 'We appreciatethe assistanceof Dr.G. R. Needham atively long periodsof acclimationto low in determininghemolymph melting points and we thank Dr. J. J. McGrathfor his commentson the temperaturelasting more than 1 day, or manuscript.This researchwas supportedin part by more commonly, weeks (Ring 1981; Lee grantno. 8300051from USDA-CRGO to D.L.D.and and Baust 1985).But, in this studyof Sar- by the NationalScience Foundation, DCB-8517875 cophaga crassipalpis,we find that a very to R.E.L. short (10 min-2 h) exposureto low tem- 2 Presentaddress: Department of Entomology,Ohio has a in StateUniversity, 1735 Neil Avenue,Columbus, Ohio perature dramaticeffect allowing 43210. flies, even nondiapausingones, to survive 3 Presentaddress: Department of Zoology,Miami subzerotemperatures. University-Hamilton, 1601 Peck Boulevard,Ham- does not tolerate Ohio 45011. Sarcophagacrassipalpis ilton, tissuefreezing at any stageof development (Leeand 1985).The SCPin both Physiol.Zool. 60(3):297-304. 1987. Denlinger @ 1987by The Universityof Chicago.All diapausing and nondiapausingpupae is rightsreserved. 0031-935X/87/6003-8663$02.00 around -23 C, but diapausingpupae are 297 This content downloaded from 134.53.236.18 on Thu, 25 Feb 2016 14:44:30 UTC All use subject to JSTOR Terms and Conditions 298 C. CHEN, D. DENLINGER,AND R. LEE, JR. able to survivetemperatures near the SCP LOW-TEMPERATUREEXPOSURE only afterbeing in diapauseseveral weeks. Pupae used for low-temperatureexpo- Nondiapausingpupae, although they have surewere placed in testtubes (10 X 1.5cm). the same low SCP, are unable to survive Eachtreatment consisted of threereplicates temperaturesapproaching the SCP (Lee of 15-20 pupae each. After exposuresof and Denlinger1985). variousdurations to chillingtemperatures This studyfocuses mainly on the pharate (0 and/or -5 + 1 C), pupaewere exposed adultstage of nondiapausingflesh flies and to temperaturesof -10 C or below using a describesthe effectof briefperiods of chill- LaudaRMT-20 (Brinkmann) low-temper- ing at 0 C on enhancingthe fly's capacity ature bath filled with water and ethylene to surviveat lower temperatures(-10 C). glycol (1:1).All pupaewere then returned Several other developmental stages, in- to 26 C until adultemergence. cludingflies programmed for diapause,are also examined.We test the possibilitythat CRYOPROTECTANTDETERMINATION cryoprotectantlevels may riserapidly in re- Low molecular were an- to ex- weightpolyols sponse short-term,low-temperature alyzed by high performanceliquid chro- posure. matography (Waters Associates) as de- MATERIALAND METHODS scribedby Lee et al. (1983). Sampleswere storedin a freezerat -40 C beforeanalysis. INSECTREARING For each extraction,two specimenswere A colony of the flesh fly, Sarcophaga weighed and homogenized in 3 ml of crassipalpisMacquart, was maintainedin methanol in a Teflon-glasstissue homog- the laboratoryas describedby Denlinger enizer for two 20-s intervals.The homog- (1972). Parentaladults were reared at 25 C enizer was rinsedwith 2 ml of methanol with either a diapause-inducingphotope- and the samplecentrifuged at 2,000 g for riod (12L:12D) or a nondiapausephoto- 5 min. The supernatantwas transferredto period (15L:9D). Larvaeand pupae were a clean sample tube, and the pellet was kepteither at 20 or 25 C underthe maternal reextractedtwo more times with 3 ml of photophase.Short-day conditions at 20 C methanol. The pooled supernatantwas producea high incidence(>95%) of pupal forcedthrough a prewashed(2 ml methanol diapause.The developmentalstatus of each and 2 ml distilledwater) Sep-Pak C18 car- pupa was determinedby removingthe an- tridge and evaporatedto drynessusing a teriorportion of the pupariumand looking Reacti-Vap evaporator (Price Chemical forsigns of antennalformation and the eye- Co.) with low heat and compressedair for pigmentation characteristicsof pharate 3 h. The samplewas then resuspendedin adult development (Fraenkeland Hsiao a 0.5-ml ethanol:watermixture (1:1) and 1968). filteredthrough a 0.22-rgmfilter and ana- concentrationswere ex- DEVELOPMENTALSTAGES lyzed. Glycerol pressedin mM units based on water-con- At 20 C, larvaefeed forabout 7 daysand tent data (Adedokunand Denlinger1985) then leave the food as third instar larvae reportedfor correspondingdevelopmental and enter a wanderingphase that lasts 4 stagesof the same species. days for nondiapause-destinedlarvae and 6 days for diapause-destinedlarvae. Pupa- tion occurs4 days afterpupariation, and, MELTINGPOINT DETERMINATION if diapause intercedes, development is Hemolymphmelting points were mea- halted at the stage of the phanerocephalic suredwith a nanoliterosmometer (Clifton pupa.In nondiapausepupae, pigmentation TechnicalPhysics) using the method de- is visible 14 days after pupariation, and scribedby Frickand Sauer(1973). Standard adults emerge aroundday 21. At 25, pu- osmolarconcentrations and distilledwater pariationoccurs 4 daysearlier, and the time wereused with each sample platform. Dur- frompupariation to adulteclosion is 9 days ing the melting process,temperature was less. Diapausecan be maintainedat 20 C slowlyincreased until only a single crystal for more than 120 days,but some individ- was visible. Readingsin mosmolarswere uals startbreaking diapause after 60 days. transformedto melting