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Constant illumination reduces circulating melatonin and impairs immune function in the cricket Teleogryllus commodus.

Durrant J, Michaelides EB, Rupasinghe T, Tull D, Green MP, Jones TM - PeerJ (2015)

Bottom Line: It is proposed that the associated suppression of melatonin (a ubiquitous hormone and powerful antioxidant) in response to the presence of light at night could be an underlying mechanistic link driving the changes to immune function.Crickets were reared under either a 12 h light: 12 h dark regimen or a constant 24 h light regimen.This study provides insight into the possible negative effect of artificial night-time lighting on the physiology of invertebrates, but whether lower and potentially more ecologically relevant levels of light at night produce comparable results, as has been reported in several vertebrate taxa, remains to be tested.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of BioSciences, The University of Melbourne , Melbourne, Victoria , Australia.

ABSTRACT
Exposure to constant light has a range of negative effects on behaviour and physiology, including reduced immune function in both vertebrates and invertebrates. It is proposed that the associated suppression of melatonin (a ubiquitous hormone and powerful antioxidant) in response to the presence of light at night could be an underlying mechanistic link driving the changes to immune function. Here, we investigated the relationship between constant illumination, melatonin and immune function, using a model invertebrate species, the Australian black field cricket, Teleogryllus commodus. Crickets were reared under either a 12 h light: 12 h dark regimen or a constant 24 h light regimen. Circulating melatonin concentration and immune function (haemocyte concentration, lytic activity and phenoloxidase (PO) activity) were assessed in individual adult crickets through the analysis of haemolymph. Constant illumination reduced melatonin and had a negative impact on haemocyte concentrations and lytic activity, but its effect on PO activity was less apparent. Our data provide the first evidence, to our knowledge, of a link between exposure to constant illumination and variation in haemocyte concentration in an invertebrate model, while also highlighting the potential complexity of the immune response following exposure to constant illumination. This study provides insight into the possible negative effect of artificial night-time lighting on the physiology of invertebrates, but whether lower and potentially more ecologically relevant levels of light at night produce comparable results, as has been reported in several vertebrate taxa, remains to be tested.

No MeSH data available.


Related in: MedlinePlus

Circulating melatonin concentrations.Median circulating melatonin concentrations (pg/ml) of 22 day-old crickets, measured from haemolymph samples taken during the light period for LD (dark grey) and LL (light grey) crickets (LD N = 20; LL N = 10). Error bars indicate interquartile ranges about the median; different letters indicate significant differences between groups (P < 0.05).
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fig-1: Circulating melatonin concentrations.Median circulating melatonin concentrations (pg/ml) of 22 day-old crickets, measured from haemolymph samples taken during the light period for LD (dark grey) and LL (light grey) crickets (LD N = 20; LL N = 10). Error bars indicate interquartile ranges about the median; different letters indicate significant differences between groups (P < 0.05).

Mentions: A total of 20 out of 57 LD samples (35.1%; females = 9; males = 11) and 10 out of 44 LL samples (22.7%; females = 6; males = 4) were above the detectable assay limit of 25 pg/ml in haemolymph. A comparison of the experimental samples above 25 pg/ml showed that melatonin concentrations were higher in LD crickets compared to LL crickets (Ln transformed data: P = 0.03; Table 1D and Fig. 1).


Constant illumination reduces circulating melatonin and impairs immune function in the cricket Teleogryllus commodus.

Durrant J, Michaelides EB, Rupasinghe T, Tull D, Green MP, Jones TM - PeerJ (2015)

Circulating melatonin concentrations.Median circulating melatonin concentrations (pg/ml) of 22 day-old crickets, measured from haemolymph samples taken during the light period for LD (dark grey) and LL (light grey) crickets (LD N = 20; LL N = 10). Error bars indicate interquartile ranges about the median; different letters indicate significant differences between groups (P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4558066&req=5

fig-1: Circulating melatonin concentrations.Median circulating melatonin concentrations (pg/ml) of 22 day-old crickets, measured from haemolymph samples taken during the light period for LD (dark grey) and LL (light grey) crickets (LD N = 20; LL N = 10). Error bars indicate interquartile ranges about the median; different letters indicate significant differences between groups (P < 0.05).
Mentions: A total of 20 out of 57 LD samples (35.1%; females = 9; males = 11) and 10 out of 44 LL samples (22.7%; females = 6; males = 4) were above the detectable assay limit of 25 pg/ml in haemolymph. A comparison of the experimental samples above 25 pg/ml showed that melatonin concentrations were higher in LD crickets compared to LL crickets (Ln transformed data: P = 0.03; Table 1D and Fig. 1).

Bottom Line: It is proposed that the associated suppression of melatonin (a ubiquitous hormone and powerful antioxidant) in response to the presence of light at night could be an underlying mechanistic link driving the changes to immune function.Crickets were reared under either a 12 h light: 12 h dark regimen or a constant 24 h light regimen.This study provides insight into the possible negative effect of artificial night-time lighting on the physiology of invertebrates, but whether lower and potentially more ecologically relevant levels of light at night produce comparable results, as has been reported in several vertebrate taxa, remains to be tested.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of BioSciences, The University of Melbourne , Melbourne, Victoria , Australia.

ABSTRACT
Exposure to constant light has a range of negative effects on behaviour and physiology, including reduced immune function in both vertebrates and invertebrates. It is proposed that the associated suppression of melatonin (a ubiquitous hormone and powerful antioxidant) in response to the presence of light at night could be an underlying mechanistic link driving the changes to immune function. Here, we investigated the relationship between constant illumination, melatonin and immune function, using a model invertebrate species, the Australian black field cricket, Teleogryllus commodus. Crickets were reared under either a 12 h light: 12 h dark regimen or a constant 24 h light regimen. Circulating melatonin concentration and immune function (haemocyte concentration, lytic activity and phenoloxidase (PO) activity) were assessed in individual adult crickets through the analysis of haemolymph. Constant illumination reduced melatonin and had a negative impact on haemocyte concentrations and lytic activity, but its effect on PO activity was less apparent. Our data provide the first evidence, to our knowledge, of a link between exposure to constant illumination and variation in haemocyte concentration in an invertebrate model, while also highlighting the potential complexity of the immune response following exposure to constant illumination. This study provides insight into the possible negative effect of artificial night-time lighting on the physiology of invertebrates, but whether lower and potentially more ecologically relevant levels of light at night produce comparable results, as has been reported in several vertebrate taxa, remains to be tested.

No MeSH data available.


Related in: MedlinePlus