No abstract

Artificial light at night is constantly minimizing the span of dark nights' from the natural lightdark cycle of earth. Over the past century, the 'lightscape' of earth has completely changed owing to technological advancements which subsequently changed the lifestyle of human as well as the nearby animal species. This motivated the present study, wherein we investigated the impact of light at night (LAN) on behavior and physiology of a diurnal passerine finch, baya weaver (Ploceus philippinus). A group of bird (N=10) exposed to 12L:12D photoperiod was initially subjected to dark nights (0 lux) for a period of 10 days followed by 5 lux; night light for a span of 4 weeks. First week in LAN served as acute treatment with respect to fourth week (chronic). Acute exposure had more pronounced impact on the behavioral and physiological observations when compared with chronic treatment. The results reveal significant increase in nighttime activity, sleep loss, significant inclusion of drowsiness behavior during the day in response to LAN. Beside these behavioral alterations, changes in physiological parameters such as; reduction in body mass, loss of gradient between pre-and post-prandial blood glucose levels, elevation in plasma corticosterone levels were more prominent during acute exposure of LAN.Plasma metabolites such as triglycerides, total protein, serum glutamic-oxaloacetic transaminase (SGOT) and creatinine concentrations also hiked in response to LAN treatment. Thus, the study broadly enumerates the impact of acute and chronic exposure of LAN on behavior (rest/sleep) and physiology (metabolism) of birds'.

No abstract

We investigated time course of photoperiodically driven transcriptional responses in physiologically contrasting seasonal life-history states in migratory blackheaded buntings. Birds exhibiting unstimulated winter phenotype (photosensitive state; responsive to photostimulation) under 6-h short days, and regressed summer phenotype (photorefractory state; unresponsiveness to photostimulation) under 16-h long days, were released into an extended light period up to 22 h of the day. Increased tshβ and dio2, and decreased dio3 mRNA levels in hypothalamus, and low prdx4 and high il1β mRNA levels in blood confirmed photoperiodic induction by hour 18 in photosensitive birds. Further, at hours 10, 14, 18 and 22 of light exposure, the comparison of hypothalamus RNA-Seq results revealed transcriptional differences within and between states. Particularly, we found reduced expression at hour 14 of transthyretin and proopiomelanocortin receptor, and increased expression at hour 18 of apolipoprotein A1 and carbon metabolism related genes in the photosensitive state. Similarly, valine, leucine and isoleucine degradation pathway genes and superoxide dismutase 1 were upregulated, and cocaine- and amphetamine-regulated transcript and gastrin-releasing peptide were downregulated in the photosensitive state. These results show life-history-dependent activation of hypothalamic molecular pathways involved in initiation and maintenance of key biological processes as early as on the first long day.

Artificial light at night is constantly minimizing the span of dark nights' from the natural light-dark cycle of earth. Over the past century, the 'lightscape' of earth has completely changed owing to technological advancements which subsequently changed the lifestyle of human as well as nearby animal species. This motivated the present study, wherein we investigated the impact of light light at night (LAN) on behavior and physiology of a diurnal passerine finch,baya weaver (Ploceus philippinus). A group of bird (N=10) exposed to 12L:12D photoperiod was initially subjected to dark nights (0 lux) for a period of 10 days followed by 5 lux; night light for a span of 4 weeks. First week in LAN served as acute treatment with respect to fourth week (chronic). Acute exposure had more pronounced impact on the behavioral and physiological observations when compared with chronic treatment. The results reveal significant increase in nighttime activity, sleep loss, significant inclusion of drowsiness behavior during the day in response to LAN. Besides these behavioral alterations, changes in physiological parameters such as; reduction in body mass, loss of gradient between pre and post-prandial blood glucose levels, elevation in plasma corticosterone levels were more prominent during acute exposure of LAN. Plasma metabolites such as triglycerides, total protein, SGOT and creatinine concentrations also hiked in response to LAN treatment. Thus, the study broadly enumerates the impact of acute and chronic exposure of LAN on behavior and physiology of birds.