The effects of continuous light exposure on Syrian hamster suprachiasmatic (SCN) neuronal discharge activity in vitro

1991 ◽  
Vol 123 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Robert Mason
2003 ◽  
Vol 34 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Cristina Tomas-Zapico ◽  
Ana Coto-Montes ◽  
Jorge Martinez-Fraga ◽  
Maria Josefa Rodriguez-Colunga ◽  
Delio Tolivia

2016 ◽  
Vol 5 (11) ◽  
pp. 5016 ◽  
Author(s):  
K. B. Khare* ◽  
Loeto D. ◽  
Wale K. ◽  
Salani M.

Seeds of three cowpea cultivars namely Black eye, ER 7 and Tswana obtained from the Department of Agriculture Research, Gaborone were tested for the presence of seed-borne fungi, and their possible control in vitro using locally available fungicides. Four hundred fifty seeds of each cultivar of cowpea were disinfected with 2% sodium hypochlorite solution for 10 min and washed three times with sterile distilled water before placing them in PDA plates (5 seeds/9 cm Petri plate), incubated at 22±2o C for 12 hour each under continuous light and dark. A total of eight fungi were detected from seeds of cowpea. These were Aspergillus flavus, A. niger, Cylindrocarpon sp., Fusarium equisiti, F. oxyaporum, Penicillium chyrosogenum, Rhizopus oligosporus and R. stolonifer. Rhizopus spp. were dominant fungi recovered from seeds, followed by Penicillium, Aspergillus, Fusarium and Cylindrocarpon. The fungi detected resulted in decay and rotting of seeds, and thereby reducing percentage germination of seeds (22%, 37% and 63 % seed germination in Black eye, ER7 and Tswana varieties of cowpea respectively). Out of four fungicides tested, benlate, captan, dithane M 45 and chlorothalanil. Dithane M45 effectively controlled seed-borne fungi, and enhanced seed germination to an average of 86% (93% germination with no fungi detected in Tswana variety) as compared to chlorothalonile (79%), benlate and captan (77%) and un-treated seeds (45%). The fungal incidence was reduced to 2.3%, 4.3%, 5.3% and 5.3% when seeds were treated with dithane M-45, chlorothalonil, benlate and captan respectively as compared to 62% in non-treated seeds.


SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A45-A46
Author(s):  
Skyler Kanegi ◽  
Armen Akopian

Abstract Introduction The combination of artificial light and lack of exposure to natural light can delay the circadian clock, dysregulate the circadian cycle, and decrease alertness upon waking. This effect has been especially significant during the COVID-19 pandemic, where overexposure to artificial light at improper hours has contributed to increased rates of clinical insomnia. Artificial light may also contribute to concomitant neurological conditions such as primary headache, but the mechanisms by which light triggers sleep deprivation-induced headache are not well-understood. Methods To measure pain sensitivity, we habituated 13 wild-type male mice to von Frey filaments applied to the periorbital area until there was no response to 0.6g stimulus. We then applied 5 lux of continuous dim light to mice during their usual 12-hour dark cycle. The 12-hour light cycle remained unchanged with 200 lux continuous light. Three groups of mice experienced the dim light stimulus for one, three, or five consecutive days. Ambulation and rest activity were measured using SOF-812 Activity Monitor machines. After the experiment concluded, we waited 24 hours and measured mechanical threshold using von Frey filaments at 1, 3, 5, 8, and every 3 days subsequently until mice no longer responded to 0.6g stimulus. Results Artificial light triggered changes in circadian behavior including increased number of rest periods during 12-hour dark (dim light) cycle and shortened sleep duration during 12-hour light cycle. Following the artificial light stimulus, there was a significant decrease in mechanical threshold (P<0.05), representing allodynia. The one-day group displayed one day of significant allodynia. The three-day group displayed three days of significant allodynia. The five-day group displayed five days of significant allodynia. Conclusion Artificial light may trigger circadian dysregulation, and the duration of artificial light exposure seemed to be directly correlated to the duration of allodynia up to one week after the stimulus was removed. We will repeat these experiments and analyze CNS and PNS tissue samples to understand the underlying physiological and biochemical bases of how artificial light triggers sleep deprivation-induced headache. This knowledge could increase our understanding of the pathophysiology and comorbidity of sleep deprivation and headache. Support (if any) Funding was received from the National Institute of Health (NS104200).


2018 ◽  
Vol 41 (1) ◽  
pp. 128-131 ◽  
Author(s):  
Tugce Ipek ◽  
Mariana Petronela Hanga ◽  
Andreas Hartwig ◽  
James Wolffsohn ◽  
Clare O’Donnell

1961 ◽  
Vol 36 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Richard Jay Wurtman ◽  
Willard Roth ◽  
Mark D. Altschule ◽  
Judith J. Wurtman

ABSTRACT Either exposure to constant light for 80 days or pinealectomy produced similar changes in the weights of the ovaries and adrenals of female rats. These were not additive when both procedures were employed. Pinealectomy did not share with light-exposure the capacity to induce uterine hypertrophy. Rats exposed to constant light for 56 days had lighter pineals than animals kept in darkness; this decrease was not affected by administration of bovine pineal extracts. The increase in ovarian weight produced in rats by exposure to light for 56 days was prevented by bovine pineal extracts, but these extracts were without effect on the uterine hypertrophy produced under the same conditions. These data suggest that the effect of light upon the weight of the ovary is mediated via the pineal.


1983 ◽  
Vol 3 (5) ◽  
pp. 931-945
Author(s):  
B D Crawford ◽  
J C Barrett ◽  
P O Ts'o

Analysis of the role of gene mutations in the multistep process of neoplastic transformation requires that the discrete steps in carcinogenesis first be dissected. Toward this end, we have isolated and characterized preneoplastic Syrian hamster cells which exhibit in vitro a trait highly correlated with neoplastic conversion in vivo. Previous findings (J. C. Barrett, Cancer Res. 40:91-94, 1980) indicate that spontaneous neoplastic transformation of Syrian hamster cells occurs in at least two steps. An intermediate stage, characterized by an aneuploid established cell line which has a propensity to become neoplastic spontaneously upon further growth in vitro, has been described. These preneoplastic cells differ from diploid early-passage Syrian hamster cells in becoming capable of anchorage-independent growth in semisolid agar, as well as becoming neoplastic in vivo when attached to a solid substrate. Evidence presented here demonstrates that anchorage-independent conversion in vitro is a reliable marker for neoplastic conversion in this cell system. Fluctuation analyses, patterned after those described by Luria and Delbruck for microbial genetics, demonstrate that anchorage-independent variants are generated randomly from clonally derived preneoplastic cells at the rate of 10(-8) to 10(-7) variants per cell per generation. These results establish a multistep stochastic process for transformation in vitro and indicate that conversion to anchorage independence may be necessary for Syrian hamster cells to become tumorigenic. The possible role of gene mutation in this step during neoplastic progression is discussed.


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