The daily cercarial emission rhythm of Schistosoma margrebowiei with particular reference to dark period stimuli

1991 ◽  
Vol 65 (3) ◽  
pp. 159-168 ◽  
Author(s):  
K. Raymond ◽  
A. J. Probert
Keyword(s):  
Light Intensity ◽  
Dark Period ◽  
Sudden Change ◽  
Gradual Change ◽  
Dark Cycle ◽  
Constant Illumination ◽  
Dark Treatment ◽  
Two Peaks ◽  
Host Parasite ◽  
Peak Emission

ABSTRACTThe cercariae of Schistosoma margrebowiei showed two peaks of emergence from Bulinus natalensis in a 12 h light/dark cycle. Peak emission occurred at 0700 h (one hour after the onset of light) and at 1900 h (one hour after the onset of darkness). Both peaks were of equal magnitude and were maintained during constant illumination indicating that the rhythm is innate. Delaying or advancing the timing of the dark period did not affect the timing of these two peaks. Following a five minute dark treatment elevation in cercarial output resulted irrespective of when the treatment was applied. Subjecting snails to various intensities of light only resulted in an elevation in output when a sudden change in intensity from 0 to 360 Lux or the reverse was applied. No response was seen to a gradual change in light intensity although the parasite could detect a change in light from 1 to 0 Lux. These responses appear to optimize the chances of host parasite contact.

scholarly journals Effect of Light Regiment on Farrowing Performance and Behavior in Sows

Animals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2858
Author(s):  
Shelby McLoda ◽  
Nichole C. Anderson ◽  
Jennifer Earing ◽  
Drew Lugar
Keyword(s):  
Light Exposure ◽  
Sudden Change ◽  
Total Duration ◽  
Light Treatment ◽  
Gestation Length ◽  
Dark Cycle ◽  
Dark Treatment ◽  
And Behavior ◽  
Effect Of Light

The purpose of this study was to investigate the effects of light exposure on farrowing performance in sows. Thirty sows were moved to the farrowing unit at d 110 of gestation and assigned a treatment: 12 h light/12 h dark cycle (Dark) or 24 h light (Light). Treatments began upon entry into the farrowing unit. Video was recorded continuously from initiation of the treatments until completion of farrowing. Data collected included duration of farrowing, birthing interval, and behavior during farrowing. Additionally, the number of total born, liveborn, and stillborn piglets was recorded. Gestation length was different between treatments, with a shorter gestation in Dark treatment sows than Light treatment sows (116.4 vs. 117.1 ± 0.2 d, respectively; p = 0.027). The total duration of parturition and number of liveborn did not differ (p = 0.393). Number of stillborn piglets between treatments did differ (p = 0.018). Dark had more stillborns compared to Light treatment sows (1.5 vs. 0.7 ± 0.2 piglets, respectively). Neither the interval between piglets nor farrowing behavior differed between treatments (p > 0.100). The results from this experiment indicate that a sudden change in photoperiod has the potential to impact the gestation length of sows and number of stillborn pigs.

Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
Keda Wang ◽  
Haoyue Zhang ◽  
Jian Zhang ◽  
Jessica M. Owens ◽  
Jennifer Weinberg-Wolf ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Sudden Change ◽  
Chemical Vapor ◽  
Threshold Value ◽  
Ir Absorption ◽  
Sudden Increase ◽  
Hot Wire ◽  
Hydrogen Dilution ◽  
Integral Absorption ◽  
Two Peaks

Abstracta-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, 0<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

Salmon and Eel Movement in Constant Circular Current

1949 ◽  
Vol 7c (7) ◽  
pp. 432-448 ◽  
Author(s):  
Viola M. Davidson
Keyword(s):  
Light Intensity ◽  
Shallow Water ◽  
Deep Water ◽  
Sudden Change ◽  
Circular Current

Underyearling salmon in a circular pond of moving water at 20–25 °C. swam during the day and rested on the bottom at night. Before feeding they translocated actively upstream in rapid shallow water and in all directions in slow deep water. During feeding they held position in slow water, but made short excursions to seize food. After feeding, most moved into rapid, shallow water, the largest into the most rapid water.Translocating salmon usually went upstream and swam faster in more rapid water so that the rate of translocation remained constant. The rate of translocation increased with the size of the fish, more than doubling from 3 to 4 cm. in length.While steady illumination caused the salmon to swim up in the water from the bottom, a sudden change in light intensity when they were swimming, as by an object moving against the sky, caused them to swim quickly from shallow to deep water.Eels translocated upstream regularly only in the more rapid water, the swimming rate increasing with current rate. Eels 7 cm. long translocated almost twice as rapidly as salmon 3.5 cm. long. Eels burrowed in the gravel in bright daylight, came out in the evening and translocated rapidly even at night when the salmon were resting.

Stimulation of Melatonin Receptors Decreases Calcium Levels in Xenopus Tectal Cells by Activating GABAC Receptors

2005 ◽  
Vol 94 (2) ◽  
pp. 968-978 ◽  
Author(s):  
Claudia Prada ◽  
Susan B. Udin ◽  
Allan F. Wiechmann ◽  
Irina V. Zhdanova
Keyword(s):  
Receptor Antagonist ◽  
Dark Period ◽  
Light Period ◽  
Melatonin Receptors ◽  
Receptor Activity ◽  
Calcium Dynamics ◽  
Rt Pcr ◽  
Dark Cycle ◽  
Bath Application ◽  
Stimulation Of

To investigate the physiological effects of melatonin receptors in the Xenopus tectum, we have used the fluorescent indicator Fluo-4 AM to monitor calcium dynamics of cells in tectal slices. Bath application of KCl elicited fluorescence increases that were reduced by melatonin. This effect was stronger at the end of the light period than at the end of the dark period. Melatonin increased γ-aminobutyric acid-C (GABAC)–receptor activity, as demonstrated by the ability of the GABAC-receptor antagonists, picrotoxin and TPMPA, to abolish the effects of melatonin. In contrast, neither the GABAA-receptor antagonist bicuculline nor the GABAB-receptor antagonist CGP 35348 diminished the effects of melatonin. RT-PCR analyses revealed expression of the 3 known melatonin receptors, MT1 (Mel1a), MT2 (Mel1b), and Mel1c. Because the effect of melatonin on tectal calcium increases was antagonized by an MT2-selective antagonist, 4-P-PDOT, we performed Western blot analyses with an antibody to the MT2 receptor; the data indicate that the MT2 receptor is expressed primarily as a dimeric complex and is glycosylated. The receptor is present in higher amounts at the end of the light period than at the end of the dark period, in a pattern complementary to the changes in melatonin levels, which are higher during the night than during the day. These results imply that melatonin, acting by MT2 receptors, modulates GABAC receptor activity in the optic tectum and that this effect is influenced by the light–dark cycle.

Effect of Monochromatic Green LED Light Stimuli During Incubation on Embryo Growth, Hatching Performance, and Hormone Levels

2018 ◽  
Vol 61 (2) ◽  
pp. 661-669 ◽  
Author(s):  
Yue Yu ◽  
Zhanming Li ◽  
Zhengtao Zhong ◽  
Shufang Jin ◽  
Jinming Pan ◽  
...  
Keyword(s):  
Light Intensity ◽  
Green Light ◽  
Light Treatment ◽  
High Light ◽  
Low Light ◽  
Dark Treatment ◽  
Led Light ◽  
Green Led ◽  
Serum Hormone ◽  
Light Stimuli

Abstract. Previous research indicated improvement of incubation by light stimuli. However, the light source arrangement, usually with irradiation from top to bottom, was inconvenient and high in cost. Among the different light colors, the effects of green LED light stimuli during embryo development were inconclusive. In this study, two LED lamps were installed on both sides of egg trays, and the irradiation was directed from the edges to the middle. The effect of green LED light with various light intensities was investigated. A total of 1408 broiler eggs were randomly allocated to high light (300 lx), middle light (150 lx), low light (50 lx), and dark treatments with four replicates. Embryo weight, body length, organ weight, hatching performance, and serum hormone levels were tested. The results indicated that incubation of the broiler eggs under an appropriate light intensity (low light treatment, 50 lx) of green light significantly increased embryo weight, body length, and hatchability (p &lt; 0.001). According to the serum hormone tests, only the low light treatment significantly increased the thyroxine (T4) levels of the chicks (p &lt; 0.05) at hatching, but the middle and high light treatments slightly decreased the T4 and testosterone (TES) levels of the chicks compared with the dark treatment. Moreover, peak hatching time occurred 12 h earlier in the light treatments compared with the dark treatment. In conclusion, an appropriate light intensity (low light treatment, 50 lx) of LED green light improved embryo growth and hatching performance, but excessive light intensity reduced the positive effects or even produced slight negative effects on the T4 and TES levels of chicks at hatching. Keywords: Embryo, Growth, Hatching performance, Hormone, Monochrome green light.

Stress and adrenocorticosteroid dynamics in the goldfish, Carassius auratus

1975 ◽  
Vol 53 (8) ◽  
pp. 1012-1020 ◽  
Author(s):  
James N. Fryer
Keyword(s):  
Significant Variation ◽  
Carassius Auratus ◽  
Dark Period ◽  
Serum Cortisol ◽  
Light Period ◽  
Sham Injection ◽  
Goldfish Carassius Auratus ◽  
Competitive Protein Binding ◽  
Two Peaks ◽  
Circulating Levels

In goldfish serum, cortisol was found to constitute 77.6% of the adrenocorticosteroids measured by a competitive protein-binding radioassay. Adult goldfish maintained on a photoperiod of 14 h light: 10 h dark in November exhibited no significant variation in serum corticosteroid concentration throughout the 24-h cycle. Goldfish maintained in an 8L:16D photoperiod in June exhibited two peaks in serum adrenocorticosteroid concentration. Four hours before the onset of the light period and 4 h after the onset of the light period, serum corticosteroids were significantly higher than those observed at the midpoint of the dark period. After sham injection, swimming in shallow water, or a thermal shock, but not a handling disturbance, circulating levels of corticosteroids were significantly higher than in undisturbed fish. Betamethasone injected 24 h before a thermal stress completely blocked the stress-induced increase in serum corticosteroids observed in vehicle-injected and uninjected goldfish, demonstrating the potency of this steroid as a blocker of the pituitary–interrenal axis in this species.

Metabolic adjustments during daily torpor in the Djungarian hamster

1999 ◽  
Vol 276 (5) ◽  
pp. E896-E906 ◽  
Author(s):  
Gerhard Heldmaier ◽  
Martin Klingenspor ◽  
Martin Werneyer ◽  
Brian J. Lampi ◽  
Stephen P. J. Brooks ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Metabolic Rate ◽  
Brown Adipose Tissue ◽  
Serum Lipids ◽  
Time Course ◽  
Gradual Change ◽  
Daily Torpor ◽  
Dark Cycle ◽  
Brown Adipose ◽  
Enzyme Changes

Djungarian hamsters ( Phodopus sungorus) acclimated to a short photoperiod (8:16-h light-dark cycle) display spontaneous daily torpor with ad libitum food availability. The time course of body temperature (Tb), metabolic rate, respiratory quotient (RQ), and substrate and enzyme changes was measured during entrance into torpor and in deep torpor. RQ, blood glucose, and serum lipids are high during the first hours of torpor but then gradually decline, suggesting that glucose is the primary fuel during the first hours of torpor, with a gradual change to lipid utilization. No major changes in enzyme activities were observed during torpor except for inactivation of the pyruvate dehydrogenase (PDH) complex in liver, brown adipose tissue, and heart muscle. PDH inactivation closely correlates with the reduction of total metabolic rate, whereas in brain, kidney, diaphragm, and skeletal muscle, PDH activity was maintained at the initial level. These findings suggest inhibition of carbohydrate oxidation in heart, brown adipose tissue, and liver during entrance into daily torpor.

Monophasic and diphasic patterns of the circadian caecotrophy rhythm of rabbits

1982 ◽  
Vol 16 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Burghart Jilge
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Light Period ◽  
Period Length ◽  
Rodent Species ◽  
Average Period ◽  
Dark Cycle

The circadian caecotrophy rhythm was synchronized with the light-dark cycle of 12 : 12 h. During this the rabbits practised caecotrophy regularly during the light period. While most rabbits manifested 1 caecotrophy per 24 h (monophasic caecotrophy), some had an additional caecotrophy during the dark period (diphasic caecotrophy). During continuous light the circadian caecotrophy rhythm ran free monophasically, even in those rabbits which were diphasic under the preceding 12 : 12 regime. The average period length amounted to 24·7 ± 0·3 h. Following restoration of the 12 : 12 routine animals reestablished their original caecotrophy pattern. In a further test the caecotrophy pattern remained constant during a constant 12 : 12 regimen, but changed in 7 of 16 animals when the photoperiod was reduced first to 60 min and then to 2 × 60 min light every 24 h. The reduction of the lit time resulted in an increased occurrence of diphasic animals. Details of synchronization of the caecotrophy rhythm with the different light-dark schedules are given. These results accord with data obtained in nocturnal rodent species.

Diurnal Differences in the Innermost Surface of the S2 Layer in Differentiating Tracheids of Cryptomeria japonica Corresponding to a Light-Dark Cycle

Holzforschung ◽  
2003 ◽  
Vol 57 (6) ◽  
pp. 567-573 ◽  
Author(s):  
Y. Hosoo ◽  
M. Yoshida ◽  
T. Imai ◽  
T. Okuyama
Keyword(s):  
Cryptomeria Japonica ◽  
Dark Period ◽  
Amorphous Material ◽  
Light Period ◽  
Cellulose Microfibrils ◽  
Dark Phase ◽  
Diurnal Changes ◽  
Dark Cycle ◽  
Tangential Strain ◽  
S2 Layer

Summary This paper describes the effect of light on the diurnal change in the innermost surface of developing secondary walls. Cryptomeria japonica D. Don saplings were grown in two growth chambers, in which temperature and relative humidity were kept constant and the light-dark phase of the photoperiod varied. One chamber reproduced the natural light-dark phase, while the other reversed it. Samples of differentiating xylem were collected during the dark period when the tangential strain, used as an index of volumetric changes in differentiating cells, was high, and during the light period when the tangential strain was low. The innermost surface of developing secondary walls in differentiating tracheids was observed by field emission scanning electron microscopy. In the specimens collected during the dark period, amorphous material was observed and the cell wall surface was immunogold-labeled with an anti-glucomannan antiserum. In the specimens collected during the light period, cellulose microfibrils were clearly evident, and amorphous material and immunogold labeling were rarely observed. These results demonstrate that the diurnal changes in the innermost surface of developing secondary walls correspond to the light-dark cycle over 24 h.

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