toggle visibility Search & Display Options

Select All    Deselect All
 |   | 
Details
   print
  Records Links
Author Arendt, J.; Middleton, B. url  doi
openurl 
  Title Human seasonal and circadian studies in Antarctica (Halley, 75 degrees S) Type Journal Article
  Year 2018 Publication General and Comparative Endocrinology Abbreviated Journal Gen Comp Endocrinol  
  Volume 258 Issue (up) Pages 250-258  
  Keywords Human Activities; Acclimatization/*physiology; Actigraphy; Adult; Antarctic Regions; Behavior/*physiology; Circadian Rhythm/*physiology; Darkness; Female; Heart Rate/physiology; Humans; Libido; Light; Male; Melatonin/blood; Photoperiod; *Seasons; Sleep/physiology; Young Adult; *Antarctica; *Circadian; *Light; *Melatonin; *Seasonal  
  Abstract Living for extended periods in Antarctica exposes base personnel to extremes of daylength (photoperiod) and temperature. At the British Antarctic Survey base of Halley, 75 degrees S, the sun does not rise for 110 d in the winter and does not set for 100 d in summer. Photoperiod is the major time cue governing the timing of seasonal events such as reproduction in many species. The neuroendocrine signal providing photoperiodic information to body physiology is the duration of melatonin secretion which reflects the length of the night: longer in the short days of winter and shorter in summer. Light of sufficient intensity and spectral composition serves to suppress production of melatonin and to set the circadian timing and the duration of the rhythm. In humans early observations suggested that bright (>2000 lux) white light was needed to suppress melatonin completely. Shortly thereafter winter depression (Seasonal Affective Disorder or SAD) was described, and its successful treatment by an artificial summer photoperiod of bright white light, sufficient to shorten melatonin production. At Halley dim artificial light intensity during winter was measured, until 2003, at a maximum of approximately 500 lux in winter. Thus a strong seasonal and circadian time cue was absent. It seemed likely that winter depression would be common in the extended period of winter darkness and could be treated with an artificial summer photoperiod. These observations, and predictions, inspired a long series of studies regarding human seasonal and circadian status, and the effects of light treatment, in a small overwintering, isolated community, living in the same conditions for many months at Halley. We found little evidence of SAD, or change in duration of melatonin production with season. However the timing of the melatonin rhythm itself, and/or that of its metabolite 6-sulphatoxymelatonin (aMT6s), was used as a primary marker of seasonal, circadian and treatment changes. A substantial phase delay of melatonin in winter was advanced to summer phase by a two pulse 'skeleton' bright white light treatment. Subsequently a single morning pulse of bright white light was effective with regard to circadian phase and improved daytime performance. The circadian delay evidenced by melatonin was accompanied by delayed sleep (logs and actigraphy): poor sleep is a common complaint in Polar regions. Appropriate extra artificial light, both standard white, and blue enriched, present throughout the day, effectively countered delay in sleep timing and the aMT6s rhythm. The most important factor appeared to be the maximum light experienced. Another manifestation of the winter was a decline in self-rated libido (men only on base at this time). Women on the base showed lower aspects of physical and mental health compared to men. Free-running rhythms were seen in some subjects following night shift, but were rarely found at other times, probably because this base has strongly scheduled activity and leisure time. Complete circadian adaptation during a week of night shift, also seen in a similar situation on North Sea oil rigs, led to problems readapting back to day shift in winter, compared to summer. Here again timed light treatment was used to address the problem. Sleep, alertness and waking performance are critically dependent on optimum circadian phase. Circadian desynchrony is associated with increased risk of major disease in shift workers. These studies provide some groundwork for countering/avoiding circadian desynchrony in rather extreme conditions.  
  Address Biochemistry and Physiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK. Electronic address: b.middleton@surrey.ac.uk  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0016-6480 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:28526480 Approved no  
  Call Number IDA @ john @ Serial 2248  
Permanent link to this record
 

 
Author Cochard, P.; Galstian, T.; Cloutier, C. url  doi
openurl 
  Title The proportion of blue light affects parasitoid wasp behavior in LED-extended photoperiod in greenhouses: Increased parasitism and offspring sex ratio bias Type Journal Article
  Year 2019 Publication Biological Control Abbreviated Journal Biological Control  
  Volume 133 Issue (up) Pages 9-17  
  Keywords Animals  
  Abstract The increasing use of specific wavelengths involving light-emitting diodes (LEDs) under greenhouses enables to overcome the lack of light during winter months, helping crops photosynthesis or vegetative growth. However, modification of the light environment as well as the photoperiod may also alter directly or indirectly the activity of both beneficial and pest insects that depend on plants. Here, we submitted the parasitic wasp Aphidius ervi and its main host the pea aphid, to 4 ratios of red(R): blue(B) LEDs used to lengthen the photoperiod inside a growth chamber. We recorded the parasitism rate of aphids and the sex ratio of newly emerged wasps to evaluate if A. ervi could remain an efficient biological control agent under modified light environments. We found that increasing the 8 h of photophase to 16 h by supplementing with R/B LEDs increased the daily parasitic activity of the wasp as well as their egg laying behavior. Under the 100R light supplement, about 80% of the emerged adults were males, against 50% under 25R:75B light treatment. These results indicate that A. ervi remains a good biological control agent when the light environment is modified. However, the use of red light to extend the photophase has the potential to negatively affect population dynamics of these parasitoids due to its male-bias impact on the sex ratio.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1049-9644 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2253  
Permanent link to this record
 

 
Author Rebke, M.; Dierschke, V.; Weiner, C.N.; Aumüller, R.; Hill, K.; Hill, R. url  doi
openurl 
  Title Attraction of nocturnally migrating birds to artificial light: The influence of colour, intensity and blinking mode under different cloud cover conditions Type Journal Article
  Year 2019 Publication Biological Conservation Abbreviated Journal Biological Conservation  
  Volume 233 Issue (up) Pages 220-227  
  Keywords Animals  
  Abstract A growing number of offshore wind farms have led to a tremendous increase in artificial lighting in the marine environment. This study disentangles the connection of light characteristics, which potentially influence the reaction of nocturnally migrating passerines to artificial illumination under different cloud cover conditions. In a spotlight experiment on a North Sea island, birds were exposed to combinations of light colour (red, yellow, green, blue, white), intensity (half, full) and blinking mode (intermittent, continuous) while measuring their number close to the light source with thermal imaging cameras.

We found that no light variant was constantly avoided by nocturnally migrating passerines crossing the sea. The number of birds did neither differ between observation periods with blinking light of different colours nor compared to darkness. While intensity did not influence the number attracted, birds were drawn more towards continuous than towards blinking illumination, when stars were not visible. Red continuous light was the only exception that did not differ from the blinking counterpart. Continuous green, blue and white light attracted significantly more birds than continuous red light in overcast situations.

Our results suggest that light sources offshore should be restricted to a minimum, but if lighting is needed, blinking light is to be preferred over continuous light, and if continuous light is required, red light should be applied.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0006-3207 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2255  
Permanent link to this record
 

 
Author Murphy, B.A. url  doi
openurl 
  Title Circadian and circannual regulation in the horse: Internal timing in an elite athlete Type Journal Article
  Year 2019 Publication Journal of Equine Veterinary Science Abbreviated Journal Journal of Equine Veterinary Science  
  Volume 76 Issue (up) Pages 14-24  
  Keywords Animals; Mammals; horses  
  Abstract Biological rhythms evolved to provide temporal coordination across all tissues and organs and allow synchronisation of physiology with predictable environmental cycles. Most important of these are circadian and circannual rhythms, primarily regulated via photoperiod signals from the retina. Understanding the nature of physiological rhythms in horses is crucially important for equine management. Predominantly, we have removed them from exposure to their natural environmental stimuli; the seasonally changing photoperiod, continuous foraging and feeding activity, social herd interactions and the continuous low intensity exercise of a grassland dweller. These have been replaced in many cases with confined indoor housing, regimental feeding and exercise times, social isolation and exposure to lighting that is often erratic and does not come close to mimicking the spectral composition of sunlight. We have further altered seasonal timing cues through the use of artificial lighting programs that impact reproductive behaviour, breeding efficiency and the development of youngstock. Understanding how these new environmental cues (some stronger, some weaker) impact the internal physiology of the horse in the context of the natural endogenous rhythms that evolved over millennia, is key to helping to improve equine health, welfare and performance, now and into the future. This review provides an overview of the field, highlights the recent discoveries related to biological timing in horses and discusses the implications that these findings may have for the production and management of the elite equine athlete.  
  Address Barbara A. Murphy, School of Agriculture and Food Science, University College Dublin, Dublin 4, Ireland; Barbara.murphy(at)ucd.ie  
  Corporate Author Thesis  
  Publisher Elseverier Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0737-0806 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2257  
Permanent link to this record
 

 
Author Datta, S.; Samanta, D.; Tiwary, B.; Chaudhuri, A.G.; Chakrabarti, N. url  doi
openurl 
  Title Sex and estrous cycle dependent changes in locomotor activity, anxiety and memory performance in aged mice after exposure of light at night Type Journal Article
  Year 2019 Publication Behavioural Brain Research Abbreviated Journal Behav Brain Res  
  Volume 365 Issue (up) Pages 198-209  
  Keywords Animals; mouse models; locomotor activities  
  Abstract Light-at-night (LAN) can affect mammalian behaviour. But, the effects of LAN on aged rodents remain undefined yet. In the present investigation, aged Swiss Albino mice, habituated in regular light-dark cycle, were exposed to bright-light-pulse (1-hr) at night on the day of study followed by experimentations for assessment of locomotor activities in the open field, anxiety in the elevated plus maze and short-term memory for novel object recognition (NOR) in the habituated field. Under without-bright-light exposure, (a) aged proestrous females showed greater locomotor activities and less anxiety than in aged diestrous females, (b) aged males showed locomotor activities and anxiety level similar to aged diestrous females and aged proestrous females respectively and (c) all animals failed to retain in object discrimination memory. LAN exposure exhibited the continual failure of such retention of memory while animals showed free and spontaneous exploration with thigmotactic behaviour having no object bias and/or phobia, but time stay in objects by animals altered variably among sexes and stages of estrous cycle. Overall, the LAN caused (a) diminution in locomotor activities, rise in anxiety and failure of memory for recognition of both familiar and novel objects in aged proestrous females, (b) hyperlocomotor activities and reduction in anxiety in both males and diestrous females with the failure of memory for recognition of novel objects only in aged males while diestrous females showed enhanced exploration time to both objects during NOR. Thus, nocturnal behaviour of aged mice varies with sex and estrous cycle and light acts differentially on them.  
  Address University of Calcutta, Department of Physiology, 92, APC Road, Kolkata, 700009, West Bengal, India. Electronic address: ncphysiolcu@gmail.com  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0166-4328 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30853396 Approved no  
  Call Number GFZ @ kyba @ Serial 2259  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print

Save Citations:
Export Records: