Quantifying biliverdin in liver and spleen samples from multiple avian species

Butler, Michael W.; Bociulis, Samantha C.; Little, Aaron R.; Minnick, Jennifer A.; Ritter, Nathan J.; Rockman, Michael E.; Rossi, Marissa L.; Hines, Justin K.

doi:10.1642/auk-16-73.1

Cited by 8 publications

(4 citation statements)

References 57 publications

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“…The transportation or deposition system in the oviduct may not always be active at the same level, but it may need to be activated when the first egg is being produced, being slightly and gradually faded out towards the end of egg laying. This may also suggest that the pigment is limited in its availability (Butler et al 2017, Morales 2020), but not in a linear way.…”

Section: Discussionmentioning

confidence: 99%

Experimentally impaired female condition does not affect biliverdin‐based egg colour

D'Arpa

Redondo

Gómez-Llanos

et al. 2022

Journal of Avian Biology

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It has been proposed that blue-green egg coloration is a condition-dependent female sexual trait that may modify paternal care in a post-mating sexual selection scenario. This pattern may arise because the pigment responsible for eggshell colouration (biliverdin) may be a costly and limited resource, whose availability is linked to female health state. Thus, it can be predicted that females whose condition is compromised should be constrained in their capacity to deposit biliverdin in the eggshell, thus producing paler clutches. To test this hypothesis, we performed a handicapping experiment by clipping some feathers of female spotless starlings before egg laying and measuring the colour of their clutches. We expected the handicapping treatment to increase flying costs, impairing female overall condition and resulting in paler clutches. Our experiment was successful in lowering the weight gain of handicapped with respect to control females. However, in contrast to our expectations, we found no effect of the treatment on eggshell colouration. Eggshell colour varied along the laying order, with initial eggs of the laying sequence being relatively paler than the rest of the clutch, but this pattern was not different between experimental groups. Despite a very similar methodology, our results differ from a previous study on the same species and offer no support to the post mating sexual selected hypothesis, questioning the general applicability of the sexual selection role of eggshell coloration.

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Section: Discussionmentioning

confidence: 99%

Experimentally impaired female condition does not affect biliverdin‐based egg colour

D'Arpa

Redondo

Gómez-Llanos

et al. 2022

Journal of Avian Biology

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“…To quantify biliverdin concentration in liver and spleen, we followed a protocol (Butler et al, 2017) that uses a protein that fluoresces in the presence of biliverdin (Berlec and Štrukelj, 2014). Specifically, we homogenized liver samples (0.11±0.0051 g; mean±s.d.)…”

Section: Measurement Of Biliverdin Concentration In Liver Spleen Andmentioning

confidence: 99%

“…Plasma samples were prepared similarly, except that we used 25-50 μl (depending on availability) of plasma and prepared a final solution with a 50:50 DMSO:ddH 2 O ratio. For liver and spleen samples, we then placed 50 µl of homogenate supernatant in duplicate into Greiner black polystyrene 96-well plates (Sigma; M0312-32EA) followed by 50 µl of biliverdin detection reagent (Butler et al, 2017) that had been thawed on ice and centrifuged at 12,000 g for 4 min immediately prior to use. For plasma samples, we used 40 μl of solution and 60 μl of biliverdin detection reagent to increase detection efficiency.…”

Section: Measurement Of Biliverdin Concentration In Liver Spleen Andmentioning

confidence: 99%

“…For example, biliverdin could function as an antioxidant (Mancuso et al, 2012) to minimize immune challengeinduced oxidative damage, or as an anti-inflammatory molecule (Wang et al, 2010) that reduces the expression of pro-inflammatory cytokines (Bisht et al, 2014) to keep the immune system from overresponding when challenged. This potential immuno-regulatory role of biliverdin has been underexplored because methods for quantifying biliverdin at physiological levels have only recently been developed (Butler et al, 2017;Berlec and Štrukelj, 2014), and because a preponderance of immunological work is conducted in mammals, which convert nearly all biliverdin to bilirubin (Bonkovsky et al, 2013;McDonagh, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Immune challenge-induced oxidative damage may be mitigated by biliverdin

Baylor

Butler

2019

Journal of Experimental Biology

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An effective immune response results in the elimination of pathogens, but this immunological benefit may be accompanied by increased levels of oxidative damage. However, organisms have evolved mechanisms to mitigate the extent of such oxidative damage, including the production and mobilization of antioxidants. One potential mechanism of mitigating immune-challenge-induced changes in oxidative physiology is increasing biliverdin production. Biliverdin is chemically an antioxidant, but within-tissue correlations between biliverdin concentration and oxidative damage have never been directly examined. To test how biliverdin tissue concentrations are associated with physiological responses to an immune challenge, we exposed northern bobwhite quail (Colinus virginianus) to one of four treatments: an injection of a non-pathogenic antigen, (i.e., either lipopolysaccharide or phytohaemagglutinin), a control injection of phosphate buffered saline, or a sham procedure with no injection. Twenty-four hours later, we quantified oxidative damage and triglyceride concentration in the plasma, and biliverdin concentration in the plasma, liver, and spleen. We found that both types of immune challenge increased oxidative damage relative to both non-injected and sham-injected controls, but treatment had no effects on any other metric. However, across all birds, oxidative damage and biliverdin concentration in the plasma were negatively correlated, which is consistent with a localized antioxidant function of biliverdin. Additionally, we uncovered multiple links between biliverdin concentration, change in mass during the immune challenge, and triglyceride levels, suggesting that pathways associated with biliverdin production may also be associated with aspects of nutrient mobilization. Future experiments that manipulate biliverdin levels or oxidative damage directly could establish a systemic antioxidant function or elucidate important physiological impacts on body mass maintenance and triglyceride storage, mobilization, or transport.

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Immune challenges decrease biliverdin concentration in the spleen of northern Bobwhite quail, Colinus virginianus

et al. 2018

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Most antioxidants have multiple functions; in addition to minimizing oxidative damage, many antioxidants have immune-modulating properties. For example, biliverdin is produced in the liver and spleen from the breakdown of heme, and has putative immune-suppressing and antioxidant properties. However, the majority of these properties have been investigated in vitro or in mammalian models, in which biliverdin reductase converts virtually all biliverdin to bilirubin. Thus, biliverdin's physiological roles remain largely untested. Here, we investigated whether biliverdin has immunomodulating roles by injecting Northern Bobwhite quail (Colinus virginianus) with either a vehicle control, lysed and rinsed pig red blood cells (pRBC) that contain erythrocyte antigens but no heme, or intact pRBC that contain both erythrocyte antigens and hemoglobin, thus increasing the amount of heme that can be converted to biliverdin. We then quantified hemagglutination and hemolysis ability, and biliverdin concentration in the liver and spleen, on 3, 6, and 9 days post-injection. We found that hemagglutination was greater in individuals that received intact pRBC, but not in those injected with heme-removed pRBC, demonstrating that biliverdin does not suppress immune function at this dosage. Biliverdin levels of liver and spleen were correlated within individuals, suggesting organism-level variation in biliverdin production. Lastly, individuals injected with intact pRBC had a reduced biliverdin concentration in the spleen, suggesting that immune challenges may reduce biliverdin production or accumulation. This initial investigation demonstrated that biliverdin may have more nuanced physiological roles than previously reported, supporting the value of further investigations into the physiology of biliverdin.

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Quantifying biliverdin in liver and spleen samples from multiple avian species

Cited by 8 publications

References 57 publications

Experimentally impaired female condition does not affect biliverdin‐based egg colour

Experimentally impaired female condition does not affect biliverdin‐based egg colour

Immune challenge-induced oxidative damage may be mitigated by biliverdin

Immune challenges decrease biliverdin concentration in the spleen of northern Bobwhite quail, Colinus virginianus

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