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Effect of the parasite Ophryocystis elektroscirrha on asymmetry and wing color of the monarch butterfly, Danaus plexippus

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Title:
Effect of the parasite Ophryocystis elektroscirrha on asymmetry and wing color of the monarch butterfly, Danaus plexippus
Translated Title:
Efecto del parasito Ophryocystis elektrosccirrha en la asimetría y color de las alas de la mariposa monarca, Danaus plexippus ( )
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English
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Landeck, Emily
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Subjects / Keywords:
Monarch butterfly   ( lcsh )
Parasites   ( lcsh )
Costa Rica--Puntarenas--Monteverde Zone--San Luis   ( lcsh )
Mariposa de monarca
Parásitos
Costa Rica--Puntarenas--Zona de Monteverde--San Luis
Tropical Ecology Fall 2009
Ecología Tropical Otoño 2009
Genre:
Reports   ( lcsh )
Reports

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Abstract:
Ophryocystis elektroscirrha, a protozoan parasite, can have many different effects on the Monarch Butterfly, Danaus plexippus, including difficulty emerging from the pupal case and spreading their wings, and increased mortality within 24 hours of eclosion. Color in the wings of the butterfly is a strong indicator of fitness in terms of reproductive success. In this study I test if parasite load has an effect on the fitness of individuals of D. plexippus using color of the wings as a proxy for fitness. I measured the wingspan; asymmetry of forewings; color hue, saturation, and brightness; and parasite load on 15 individuals of D. plexippus. There was a trend in the differences of the wingspan averages between infected and uninfected individuals: infected individuals had an smaller average wingspan, a negative trend between the wingspan and asymmetry, and positive trends between the wingspan and the two wing color values of hue and brightness. These trends could be caused by the activation of the parasites in the pupal stage of development in smaller butterflies. Therefore larger individuals have brighter more defined colors in their wings and less asymmetry, probably indicating fitter butterflies.
Abstract:
Ophryocystis elektroscirrha es un parásito protozoario que puede tener diferentes efectos en las mariposas Monarcas (Danaus plexippus), estos efectos incluyen dificultades al salir de la envoltura pupal, para extender sus alas, y además del incremento en la mortalidad después de las 24 horas de eclosión. El color en las alas de las mariposas es un fuerte indicador del éxito reproductivo. En este estudio yo probé el efecto de los parásitos en el éxito reproductivo de los individuos de D. plexipus, usando el color de las alas como una medida de éxito reproductivo. Medí el ancho del ala, la asimetría en las alas anteriores, el tono del color, la saturación, el brillo y los parásitos de 15 individuos. Hubo una tendencia en los promedios de los individuos infectados y no infectados, los individuos infectados tenían alas más pequeñas, hubo una tendencia negativa entre el tamaño del ala y la asimetría, y una relación positiva entre el tamaño del ala y los valores del tono y el brillo del color. Esta tendencia puede ser causada por la actividad de los parásitos en el estado pupal de las mariposas más pequeñas. Por lo tanto los individuos más largos tenían colores más brillantes, más definidos en sus alas y menos asimetría, lo que sugiere que son mariposas mejor adaptadas.
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Effect of the Parasite Ophryocystis elektroscirrha on Asymmetry and Wing Color of the Monarch Butterfly, Danaus Plexippus. Emily Landeck Department of Biology, University of Puget Sound ABSTRACT Ophryocystis elektroscirrha, a protozoan parasite, can h ave many different e ffects on the Monarch Butterfly, Danaus plexippus, including difficulty emerging from the pupal case and spreading their wings, and increased mortality within 24 hours of eclosion. Color in the wings of the butterfly is a strong indicat or of fitness in terms of reproductive success In this study I test if parasite load has an effect on the fitness of individuals of D. plexippus using color of the wings as a proxy for fitness I measured the wingspan; asymmetry of forewings; color hue, s aturation, and brightness; and parasite load on 15 individuals of D. plexippus There was a trend in the differences of the wingspan averages between infected and uninfected individuals: infected individuals had an smaller average wingspan, a negative tren d between the wingspan and asymmetry, and positive trends between the wingspan and the two wing color values of hue and brightness. These trends could be caused by the activation of the parasites in the pupal stage of development in smaller butterflies. Th erefore larger individuals have brighter more defined colors in their wings and less asymmetry, probably indicating fitter butterflies. RESUMEN Ophryocystis elektroscirrha es un parsito protozoario que puede tener diferentes efectos en las mariposas Mon arcas ( Danaus plexippus) Estos efectos incluyen dificultades al emerger de la pupa y al abrir sus suelos, ademas de incremento en la mortaidad despes de 24 horas de eclosion. El color en las alas de las mariposas es un fuerte indicador del xito reproduct ivo. En este estudio yo probe el efecto de los parsitos en el xito reproductivo de individuos de D. plexipus usando el color de las alas como una medida de xito reproductivo. Med el ancho del ala, asimetra en las alas anteriores, el tono del color, la saturacin, el brillo y los parasitos de 15 individuos. Hubo una tendencia en los promedios de individuos infectados y no infectados, los individuos infectados tenian alas mas pequeas, hubo una tendencia negativa entre el tamao del ala y asimetra, y una relacin positiva entre el tamao del ala y los valores del tono y brillo del color. Estas tendencia puede ser causadas por la actividad de los parsitos en el estado pupal de mariposas mas pequeas. Por lo tanot individuos mas largos tenia colores mas brillantes, mas definidos en sus alas y menos asimetra, lo que sugiere mariposas mejor adaptadas. INTRODUCTION Parasites can have many different effects on their hosts including increased mortality, increased susceptibility to disease due to a reduc ed immune system, and the control of the host populations by influencing overall fitness, reproduction and long term survival (Lanciani 1975). Many parasitic relationships can be found in nature and many involve insects and other microorganisms that can in fect the host in one or many of the life stages such as the egg, larval, pupal or even adult instar (Hsu 2004). Ophryocystis elektroscirrha is a protozoan parasite only found in the Monarch butterfly, Danaus plexippus and the Florida Queen Butterfly, Dan aus gilippus (McLaughlin & Myers 1970, in Altizer et al. 1999). According to Altizer (2001) the persistence of this particular parasite in Monarch and Queen butterflies could be due to the interactions with different host genotypes that show varying levels of susceptibility to the parasite (Leonard & Czochor 1980; Parker 1992), and it is possible that the variation in individuals could

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result in different fitness levels. Spores can be transmitted both horizontally, from the male to female during copulation or passively from adult to adult when in crowded roosting or over wintering sites. However they are mainly transmitted vertically, from the mother to her offspring (Vickerman et al. 1999). When an infected mother lays her eggs on a host plant she will ina dvertently deposit the spores of the parasite on the outside of the eggs and the host plant which the larvae eat when then hatch (Vickerman et a l 1999). In the larval gut the parasite spores lyse penetrate the hypodermal tissue and remain dormant until the pupal stage (Vickerman et al. 1999). In the pupal stage the parasite spores will reproduce sexually and asexually and sporulate within the hypodermal tissue (Vickerman et al. 1999). The adult emerges with the spores of the parasite on the external cuti cle The parasite O. elektroscirrha can have very detrimental effects on the fitness and survival of both the larval and the adult instars of D. plexippus It has been observed that adults with low parasite loads have little to no signs of weakness or lo wered overall fitness, but those with high parasite presence have difficulty emerging from the pupal case and spreading their wings (McLaughlin & Myers 1970, in Altizer et al. 2000 ; Leong et al. 1992 ) Altizer and Oberhauser (1999) found that the male butt erflies with high parasites had lower reproductive success overall The mating success in males of D. plexippus can also be correlated with wing color, or the melanism : in the wing in that males with a deeper color orange have a significantly higher matin g success than those with lighter orange (Davis et al. 2007). Therefore, if mating success and overall survival are measurements of fitness (Altizer & Oberhauser 1999) in natural interactions and wing color and size are indicators of the fitness (Davis e t al 2007) of an individual I would expect these facts would hold true in the interactions of O. elektroscirrha and D. plexippus I n this study I tested if more parasites per individual monarch will decrease the color hue, saturation and brightness values in the wings of the butterfly as well as the size of the butterfly and therefore the overall fitness of the individual. I also test size, asymmetry and parasite load against one another. Although asymmetry has not been shown to be a significant result of parasite infection (Altizer & Oberhauser 1999), there may be a positive correlation between parasites and asymmetry due to the fact that higher symmetry indicates higher fitness in other natural interactions and if the parasite is interrupting development, asymmetry may be more common on infected individuals. MATERIALS AND METHODS Wild Monarch Acquisition and Measurement Fifteen wild monarchs, D. plexippus were captured in cattle pastures with high concentrations of Asclepias curassavica in the San Luis Valley, Costa Rica. Each butterfly was sexed and the length of the two forewings was measured to calculate wingspan and asymmetry using digital images and the measurement tool in Adobe Photoshop To determine differences in coloration I used the wing co lor hue, which can be defined as the color of the wing, such as the distinction between pink, orange and red, and is measured in degrees; the saturation of the wing color which can be thought of as the amount of intensity o f color and can be measured in p ercent saturation; and the color brightness, which is considered the overall lightness of the picture (Davis et al. 2007). The color of the wing is comprised of all three components: hue, saturation and

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brightness, but I chose to analyze the affect of each component separately. The wing hue, saturation and brightness were determined using the middle cells of each forewing to assure the littlest amount of damage to the cell (Davis et al. 2007). The cell of the wing was traced using the magnetic tracing tool in Adobe Photoshop and the mean red, green, and blue values from the histogram were entered into the color picker (Grant, 2007). The values for hue, percent saturation and brightness from the color picker were then averaged separately to determine the aver age of each color value within the butterfl wings. Parasite Load Determination The parasite load of O. elektroscirrha on each butterfly was determined by combining the swab techniques as described by Hsu (2004) and Davis et al. (2004). The butterfl ies were swiped with a cotton swab from the posterior to anterior end of the abdomen 4 times, using the same swab. Both sides of the butterfly abdomen were swabbed to avoid human error. The scales and spores were transferred to a standard microscope slide and covered with scotch tape. The spores were easily distinguishable from butterfly scales due to the discrepancy in size, the spores are 1/50 th the size of a scale, and the oblong, football shape of the spores (Figure 1). The spores were counted within a 1mm 2 area of the slide and the numbers from the two sides of the butterfly were averaged to determine the overall spore load. Statistical Tests T test s w ere run to determine differences in wingspan, asymmetry and color between male and female butterflies No significant difference in wingspan, asymmetry or color between the sexes were found so the data was combined A t test was also run on wingspan versus parasite load. Pair wise correlations were run between wingspan, asymmetry, wing color hue, wing col or brightness, wing color saturation, and parasite load. RESULTS There was a trend between the wingspans of the infected and non infected individuals (Figure 2) in that the infected individuals had generally smaller wings than the non infected individual s (t = 0.986, df = 12.9997, p = 0.3420). There was a negative trend between the wing asymmetry and the wingspan of the butterfly: the bigger the butterfly the less asymmetry occurred (r = 0.293, n =15, p = 0.2 892) but no significant correlation was foun d (Figure 3). I observed a positive trend between wingspan and wing color hue (Figure 4) where larger butterflies had a higher hue degree (r = 0.4685, n =14, p = 0.0911), as well as wingspan and wing color brightness (Figure 5) where larger individuals had a higher brightness value (r = 0.4926, n = 14, p = 0.0735) All other correlations were not statistically significant and had no strong trends between the two variables (Table 1). DISCUSSION There was a trend in the difference between the average wings pans of parasite infected individuals and the uninfected individuals; the infected individuals had a smaller average wingspan. This could be because the parasites are dormant until the pupal stage, but then become active once the butterfly is eight days in to the pupal stage (Vickerman et al. 1999), therefore it is very possible that the development can be greatly hindered by the

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parasites. If the parasites are causing slowed or altered development inside the pupal growth is hindered by this and therefore the butterfly with parasites will eclose from the pupae smaller than would be expected of an uninfected individual. Because butterflies eclose at the size they will be for their life (Pablo Allen, Pers. Comm.), the parasites, although present throughout the life of the butterfly, will not hinder their growth after eclosion. Therefore, possibly the only point at which the parasites could affect the growth of the butterfly would be in the pupal stage, and the trend of smaller wingspan with higher parasites supports this hypothesis. I also observed a negative trend between asymmetry and wingspan. Asymmetry is considered a common indicator of fitness in many organisms in nature due to the fact that the more symmetrical a n organism is in appearance the more reproductively fit it is ( Hnekopp et al. 2004). But in D, plexippus it has been found that asymmetry is not an indicator of reproductive success (Davis et al. 2007). This is because most copulation occurs not by choice of the female but by force from the male (Davis et al. 2007). It has been observed that the males grab and wrestle the female to attempt copulation and although the female does not have choice based on appearance the females still attempt to wrestle the m ale s off implying that they have some kind of choice in mate selection based on strength (Davis et al. 2007). This is supported by the fact that only 30 40% of male copulation attempts are successful and that the success depends greatly on the ability of the male to wrestle the female into copulation (Davis et al. 2007). Therefore, it is assumed that asymmetry is not selected against in either sex of D. plexippus populations due to appearance but i t is possible that the asymmetry is selected for in a dif ferent way. Assymetry could be another e ffect of disruption during development. The butterflies with greater asymmetry could have more difficulty flying, and therefore migrating and mating, causing a decrease in the fitness of those individuals. If this we re the case, we would expect the smaller butterflies to have higher asymmetry because it is possible that smaller wing size correlates with disruption during development as well, and we would expect that the more asymmetrical individuals would have lower f itness overall. Other positive trends were those between wingspan and color hue; and wingspan and color brightness. Because both of these values indicate the color of the wing, both the defined color in general. The color in the butterfly wing, is an indicator of butterfly fitness through reproductive success (Davis et al. 2007). Therefore, if there is more defined color in the larger butterflies it is very likely that the larger butterf lies are more fit in terms of survival and reproduction. And because the larger butterflies are less infected overall than the smaller ones it is likely that color values in the butterfly wing are indirectly, or possibly directly, related to the parasitism of the butterfly. Although there was not a significant correlation or a general trend between parasite load and any of the color values it is possible that with a larger sample size, and therefore a higher infected to uninfected individuals ratio, there w ould be a direct significant correlation between color in the wings and parasite load. It is known that both size ( Hnekopp et al. 2004) and wing color are indicators of fitness in D. plexippus (Davis et al. 2007) and I observed a trend in the wingspan of infected and uninfected individuals in that the infected individuals had a smaller wingspan. In addition I found a positive trend between wingspan and color hue and

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wingspan and brightness. This previous knowledge and these findings lead me to believe tha t with more sampling and further research it is possible that a strong correlation could be found between the O. elektroscirrha parasite loads on an individual of D. plexippus and the wing color and definition in that individual. ACKNOWLEDGEMENTS I would like to thank Pablo Allen for all his help in designing my project, trouble shooting, capturing monarchs, and overall advising for this project. I would like to thank Abbi Smith and Kristin Omori for their help in catching monarchs in San Luis and Rachelle Sloss, Ashley Arthur and Whitney Tsai for helping with the photography of the butterflies. I would like to thank my host family Edith, Milton, Joeseth, Daniella and Kevin Brenes Salazar for their support throughout the month that I lived with them. I woul d like to thank Alan Masters for his background information on monarchs in Costa Rica and his help in designing my project and Anjali Kumar for her overall enthusiasm about my project. I would also lke to thank Nicholas Gallagher for reviewing my paper. An d finally I would like to thank La Estacin Biolgica, Monteverde for allowing me to use the lab space, the property owners in San Luis for allowing me to capture and release on their property and CIEE for supplying me with the equipment for my research. LITERATURE CITED ALLEN, P. Personal Communication. November 22, 2009. ALTIZER, S.M. and K.S. OBERHAUSER. 1999. Effects of the Protozoan Parasite Ophryocystis elektroscirrha (Danaus plexippus). Journal of Invertebrate Pathology 74: 76 88 ALTIZER, S.M., K.S. OBERHAUSER and L.P. BROWER. 2000. Associations between host migration and the prevalence of a protozoan parasite in natural populations of adult monarch butterflies. Ecological Entomology. 25: 125 139. DAVIS, A.K. S. ALTIZER and E. FRIEDLE. 2004. A non destructive, automated method of counting spores of O. elektroscirrha in infected monarch butterflies. The Florida Entomologist. 87: 231 234 DAVIS, A.K., N. COPE, A. SMITH, and M.J. SOLENSKY. 2007. Wing Color Predic ts Future 344 GRANT, J.B. 2007. Ontogenetic colour change and the evolution of aposematism: a case study in panic moth caterpillars. Journal of Animal Ecology 76: 439 447 HNEKOOP, J., T. BARTHOLOME, and G. JANSEN 2004. Facial attractiveness, symmetry, and physical fitness in young women. Human Nature. 15: 147 167 HSU, J. 2004. A Protazoan Parasite in Wild and Captive Monarch Butterfly Populations Near Montever de, Costa Rica. CIEE Fall 2004 1: 12 22 LANCIANI, C.A. 1975. Parasite Induced Alterations in Host Reproduction and Survival. Ecology 56: 689 695 LEONARD, K.J. and R.J. CZOCHOR. 1980. Theory of genetic interactions among populations of plants and their pathogens. Annual Review of Phytopathology 18: 237 258. LEONG, K. L. H., H. K. KAYA, M. A. YOSHIMURA, and D. F. FREY. 1992. The occurrence and effect of a protozoan parasite, Ophryocystis elektroscirrha ( Neogreganida: Ophryocystidae) on overwintering mon arch butterflies Danaus plexippus (Lepidoptera: Danaidae) from two California winter sites. Ecological Entomology 17:338 342. MCLAUGHLIN, R. E. and J. MYERS. 1970. Ophryocystis elektroscirrha sp. n. a neogregarine pathogen of the monarch butterfly Danau s plexippus (L.) and the Florida queen butterfly Danaus gilippus Journal of Protozoology 17:300 305. ALTIZER, S.M. and K.S. OBERHAUSER. 1999. Effects of the Protozoan Parasite Ophryocystis elektroscirrha (Danaus plexi ppus). Journal of Invertebrate Pathology 74: 76 88

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VICKERMAN, D., A. MICHELS and P. A. BURROWES. 1999. Levels of Infection of Migrating Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) by the Parasite Ophryocystis elektroscirrha (Neog regarinida: Ophryocystidae), and Evidence of a New Mode of Spore Transmission between Adults. Journal of the Kansas Entomological Society 72: 124 128 ______________________________________________________________ Figure 1. Image of the microscope view of butterfly scales and Ophryocystis elektroscirrha spores, that are much smaller and football shaped from a highly infected individual of Danaus plexippus. ______________________________________________________________ _____________________________ __________________________________ Figure 2. Comparison of the average wingspans of the 5 infected ( Avg = 24.81, SD = 2.22) and 10 uninfected( Avg = 26.69. SD = 4.99 ) individuals of Danaus plexippus _____________________________________________________ __________

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________________________________________________________________ Figure 3. Correlation between the wingspan and the asymmetry of all infected and non infected individuals of D. plexippus ______________________________________________ __________________ ____________________________________________________________ Figure 4. Correlation between wing color hue and wingspan in individuals of D. plexippus ____________________________________________________________

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_________ _______________________________________________ Figure 5. Correlation between wing color brightness and wingspan in individuals of D. plexippus ________________________________________________________ ____________________________________ ___________________________ Table 1 Table of the pair wise correlations of Monarch Butterfly, D. plexippus wingspan, asymmetry, wing color values and O. elektroscirrha parasite load with the r, n and p values. Variable 1 Variable 2 r n p Asymmetry Wingspan 0.293 15 0.2892 Hue o Wingspan 0.4685 14 0.0911 Hue o Asymmetry 0.1014 14 0.7301 % Saturation Wingspan 0.0692 14 0.8141 % Saturation Asymmetry 0.1625 14 0.5788 % Saturation Hue o 0.1916 14 0.5117 Brightness Wingspan 0.4926 14 0. 0735 Brightness Asymmetry 0.2289 14 0.4312 Brightness Hue o 0.2768 14 0.3381 Brightness % Saturation 0.402 14 0.1542 Parasites Wingspan 0.2197 15 0.4314 Parasites Asymmetry 0.1172 15 0.6773 Parasites Hue o 0.2477 14 0.3932 Parasites % Saturation 0.1785 14 0.5416 Parasites Brightness 0.0041 14 0.9889


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Efecto del parasito Ophryocystis elektrosccirrha en la asimetra y color de las alas de la mariposa monarca, Danaus plexippus
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Effect of the parasite Ophryocystis elektroscirrha on asymmetry and wing color of the monarch butterfly, Danaus plexippus
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Ophryocystis elektroscirrha, a protozoan parasite, can have many different effects on the Monarch Butterfly, Danaus plexippus, including difficulty emerging from the pupal case and spreading their wings, and increased mortality within 24 hours of eclosion. Color in the wings of the butterfly is a strong indicator of fitness in terms of reproductive success. In this study I test if parasite load has an effect on the fitness of individuals of D. plexippus using color of the wings as a proxy for fitness. I measured the wingspan; asymmetry of forewings; color hue, saturation, and brightness; and parasite load on 15 individuals of D. plexippus. There was a trend in the differences of the wingspan averages between infected and uninfected individuals: infected individuals had an smaller average wingspan, a negative trend between the wingspan and asymmetry, and positive trends between the wingspan and the two wing color values of hue and brightness. These trends could be caused by the activation of the parasites in the pupal stage of development in smaller butterflies. Therefore larger individuals have brighter more defined colors in their wings and less asymmetry, probably indicating fitter butterflies.
Ophryocystis elektroscirrha es un parsito protozoario que puede tener diferentes efectos en las mariposas Monarcas (Danaus plexippus), estos efectos incluyen dificultades al salir de la envoltura pupal, para extender sus alas, y adems del incremento en la mortalidad despus de las 24 horas de eclosin. El color en las alas de las mariposas es un fuerte indicador del xito reproductivo. En este estudio yo prob el efecto de los parsitos en el xito reproductivo de los individuos de D. plexipus, usando el color de las alas como una medida de xito reproductivo. Med el ancho del ala, la asimetra en las alas anteriores, el tono del color, la saturacin, el brillo y los parsitos de 15 individuos. Hubo una tendencia en los promedios de los individuos infectados y no infectados, los individuos infectados tenan alas ms pequeas, hubo una tendencia negativa entre el tamao del ala y la asimetra, y una relacin positiva entre el tamao del ala y los valores del tono y el brillo del color. Esta tendencia puede ser causada por la actividad de los parsitos en el estado pupal de las mariposas ms pequeas. Por lo tanto los individuos ms largos tenan colores ms brillantes, ms definidos en sus alas y menos asimetra, lo que sugiere que son mariposas mejor adaptadas.
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Parasites
Costa Rica--Puntarenas--Monteverde Zone--San Luis
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Mariposa de monarca
Parsitos
Costa Rica--Puntarenas--Zona de Monteverde--San Luis
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