Inhibition of nighttime melatonin secretion in cattle: threshold light intensity for dairy heifers

2001 ◽  
Vol 81 (1) ◽  
pp. 153-156 ◽  
Author(s):  
T. J. Lawson ◽  
A. D. Kennedy
Keyword(s):  
Light Intensity ◽  
Key Words ◽  
Latin Square ◽  
Exposure Period ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Dairy Heifers ◽  
Plasma Melatonin ◽  
Light Intensities ◽  
Lower Light

Five pre-pubertal Holstein heifers were exposed for 16 h to a light intensity of 400 lx and thereafter to intensities of 0, 50, 100, 200, or 400 lx for an additional 8 h (5 x 5 Latin square design). Exposure to all intensities inhibited (P < 0.05) melatonin secretion for the initial few hours (of the 8-h exposure period); melatonin concentration subsequently increased, particularly with the lower light intensities. Only the highest light intensity (400 lx) suppressed (P < 0.05) plasma melatonin concentrations for the entire 8-h exposure period. Key words: Threshold, supplemental, light, intensity, inhibition, melatonin, heifer

Pycnidium production by Botryodiplodia theobromae. I. The relation of light to the induction of pycnidia

1969 ◽  
Vol 47 (7) ◽  
pp. 1153-1156 ◽  
Author(s):  
J. A. Ekundayo ◽  
R. H. Haskins
Keyword(s):  
Light Intensity ◽  
Ultraviolet Radiation ◽  
Exposure Period ◽  
Fluorescent Light ◽  
Botryodiplodia Theobromae ◽  
Continuous Irradiation ◽  
Long Wave ◽  
Light Intensities ◽  
Glass Color ◽  
Color Filters

Cultures of Botryodiplodia theobromae Pat. produced pycnidia abundantly on several media under continuous irradiation with fluorescent light. The fungus did not sporulate when grown in darkness. Irradiation of cultures with a light intensity of 15 foot-candles for 4 days was sufficient to stimulate pycnidial production, but for appreciable sporulation to occur over the same exposure period, higher light intensities are required. Irradiation of cultures through glass color filters showed that long-wave ultraviolet radiation stimulated sporulation.

Cold tolerance and winter hardiness in Lolium perenne: II. Influence of light and temperature during growth and hardening

1973 ◽  
Vol 80 (2) ◽  
pp. 341-348 ◽  
Author(s):  
T. Lawrence ◽  
J. P. Cooper ◽  
E. L. Breese
Keyword(s):  
Light Intensity ◽  
Cold Tolerance ◽  
Lolium Perenne ◽  
Water Soluble ◽  
Light Conditions ◽  
Low Light ◽  
Growing Period ◽  
Light Intensities ◽  
Lower Light ◽  
Light Input

SummaryIn the first paper of this series it was shown that Lolium perenne material required hardening periods involving low, but above freezing, temperatures before frost tolerance was achieved. The present experiments show that the light conditions during the hardening and prehardening periods are also important. At both stages a reduction in total light energy reduced subsequent cold tolerance but the relative effects of light intensity and photoperiod differed between the prehardening and hardening treatments. Thus low light input during the hardening period at 2 CC reduced cold tolerance most when given at higher intensities over shorter days (8 h) while during the prehardening growing period at 20 °C the reduction was greatest when the lower light input was given at low intensity over longer days (16 h).Varieties of different climatic origins reacted differentially to the treatments. The Mediterranean variety Fano was particularly adversely affected by low light intensities during hardening and also benefited from higher temperatures during the prehardening growing period. With higher light intensities and higher growth temperatures this Mediterranean variety approached the more northern material in cold tolerance; but as a corollary it was clear that the N. European variety Veja was able to harden under lower light conditions, and lower growing temperatures. The varieties Melle and S. 321 from intermediate latitudes, were intermediate in response.Although water soluble carbohydrate content was increased during the hardening period, except at the lowest light intensity (2·9 W/m2), no simple relationship between the WSC content and the cold tolerance of the different varieties could be detected.The results provide a useful guide to the pre-treatments necessary to discriminate between varieties for cold tolerance in such a way that the results can be correlated with field performance.

scholarly journals Effect of light intensities on reproductive performance, nursing behaviour and preference of rabbit does

2016 ◽  
Vol 24 (2) ◽  
pp. 139 ◽  
Author(s):  
Zs. Matics ◽  
Zs. Szendrő ◽  
I. Radnai ◽  
R. Kasza ◽  
Zs. Gerencsér
Keyword(s):  
Light Intensity ◽  
Reproductive Performance ◽  
Preference Test ◽  
High Light Intensity ◽  
Point Of View ◽  
Light Intensities ◽  
Lower Light ◽  
Net Cages ◽  
Group D ◽  
Lower Light Intensity

The aim of the experiment was to compare the reproductive performance and nursing behaviour of rabbit does reared under 2 different light intensities and observe the preference of does among cages with different light intensities. Female rabbits were randomly housed in 2 identical rooms, under the same housing conditions in wire-net cages. The 2 rooms only differed in the light intensity; group L: 150-200 lux (n=54 does, 230 inseminations), group D: 10-20 lux (n=54 does, 232 inseminations). Reproduction data from the first 5 consecutive reproductive cycles were evaluated. Nursing behaviour of the does (n = 24) was observed at the 2nd or 4th lactation. The preference of does (n=8) among 4 cages with different light intensities (10, 35, 75 or 155 lux)  as examined. There were 6-7% difference between the 2 groups in the number of kits born in total and those born alive (born total: 11.25 vs. 10.59 kits, P&lt;0.1; liveborn: 10.75 vs. 10.00 kits, P&lt;0.05; in groups L and D, respectively). Suckling mortality was nearly 2% higher in group D (L: 8.1, D: 10.0%; P&lt;0.1), and in consequence the litter size of this group at 35 d of age was lower than that of the L rabbits (L: 8.75, D: 8.45 kits; P&lt;0.05). The light intensity did not affect litter and individual weights at 35 d of age. The average numbers of daily nursing events (L: 1.23/d, D: 1.32/d), the length (L: 208±49, D: 213±43 s) and the daily distribution of nursing events were not affected by high light intensity. During the light period of the day, the darkest cage (10 lux) was the most preferred by the does (44.0, 18.6, 17.9 and 19.5% in 10, 35, 75 and 155 lux cages, respectively; P&lt;0.001). The lower light intensity had no unambiguously unfavourable effect on the reproductive performance and nursing behaviour of the does. Based on the preference test, a lower light intensity may be advantageous from the point of view of animal welfare.

scholarly journals The effect of light intensities on morpho-physiological and biochemical of black pepper (Piper nigrum L.)

2021 ◽  
Vol 306 ◽  
pp. 01009
Author(s):  
Issukindarsyah ◽  
Endang Sulistyaningsih ◽  
Didik Indradewa ◽  
Eka T. Susila Putra
Keyword(s):  
Light Intensity ◽  
Reductase Activity ◽  
Sucrose Concentration ◽  
Morphological Characters ◽  
Black Pepper ◽  
Piper Nigrum ◽  
Light Intensities ◽  
Lower Light ◽  
The Difference ◽  
Effect Of Light

The difference in the levels of light intensity was responded with changes in morphophysiological and biochemical characters of plants, especially in leaves of black pepper. The aim of this study was to determine the effect of several levels of light intensity on the morphophysiological and biochemical characters of leaves of black pepper. The research was conducted in July - November 2017 in Kemuja, Mendobarat, Bangka Belitung. This study used split-plot design with three replications. The main plots were the levels of light intensity, namely 100%, 75%, and 50%. Subplots were varieties of black pepper, namely Petaling 1, Petaling 2, and Nyelungkup. The results showed that there was no interaction between varieties and light intensities. The morphophysiological and biochemical responses of the leaves of the three varieties tested were the same at all levels of light intensity. Light intensity up to 50% has no effect on leaf morphological characters, but leaves become thinner at lower light intensities. Chlorophyll, nitrate reductase activity and leaf sucrose concentration were same at all light intensities up to 50%. Plants exposed to higher light intensity have a higher number of stomata. The results concluded that the light intensity of up to 50% did not cause changes in leaf morphology and biochemistry and only affected leaf stomata density.

Plasma melatonin concentrations in hibernating marmots: absence of a plasma melatonin rhythm

1984 ◽  
Vol 247 (6) ◽  
pp. R1062-R1066 ◽  
Author(s):  
G. L. Florant ◽  
M. L. Rivera ◽  
A. K. Lawrence ◽  
L. Tamarkin
Keyword(s):  
Time Of Day ◽  
Tissue Temperature ◽  
Constant Darkness ◽  
Circadian Pacemaker ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Ambient Temperatures ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Deep Hibernation

Plasma melatonin concentrations were measured throughout bouts of hibernation in marmots maintained in a short photoperiod (light-dark 8:16) and ambient temperature of 5 or 15 degrees C. Melatonin concentration was also measured in two animals maintained in constant darkness. As an animal entered hibernation, plasma melatonin concentrations dropped to basal levels when body temperature reached 25 degrees C, and they remained low until arousal. During deep hibernation plasma melatonin values did not vary significantly (P greater than 0.05) with respect to time of day or different ambient temperatures. With nocturnal arousal plasma melatonin levels were similar to euthermic night values. Lack of a plasma melatonin rhythm during hibernation suggests that the pineal gland is not temperature compensated during hibernation, and due to the low tissue temperature of the pineal the circadian pacemaker driving melatonin secretion is incapable of stimulating a rhythm.

The Effect of Moderate Weight Loss on Overnight Melatonin Secretion

1990 ◽  
Vol 156 (6) ◽  
pp. 875-877 ◽  
Author(s):  
I. M. Anderson ◽  
S. E. Gartside ◽  
P. J. Cowen
Keyword(s):  
Weight Loss ◽  
Melatonin Level ◽  
Melatonin Secretion ◽  
Plasma Melatonin ◽  
Healthy Women ◽  
Before And After

Overnight plasma melatonin level was measured in ten healthy women before and after a 4300 kJ (1000 kcaI) diet in which they lost an average 3.1 kg. This weight loss did not significantly alter melatonin levels.

scholarly journals Effect of chlorophyll biosynthesis-related genes on the leaf color in Hosta (Hosta plantaginea Aschers) and tobacco (Nicotiana tabacum L.)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jingying Zhang ◽  
Changhai Sui ◽  
Huimin Liu ◽  
Jinjiao Chen ◽  
Zhilin Han ◽  
...  
Keyword(s):  
Light Intensity ◽  
Antioxidant Capacity ◽  
Aminolevulinic Acid ◽  
Chlorophyll Biosynthesis ◽  
Expression Level ◽  
Virus Induced Gene Silencing ◽  
Leaf Color ◽  
Color Changes ◽  
Light Intensities ◽  
Structure Changes

Abstract Background ‘Regal Splendour’ (Hosta variety) is famous for its multi-color leaves, which are useful resources for exploring chloroplast development and color changes. The expressions of chlorophyll biosynthesis-related genes (HrHEMA, HrPOR and HrCAO) in Hosta have been demonstrated to be associated with leaf color. Herein, we isolated, sequenced, and analyzed HrHEMA, HrPOR and HrCAO genes. Subcellular localization was also performed to determine the location of the corresponding enzymes. After plasmid construction, virus-induced gene silencing (VIGS) was carried out to reduce the expressions of those genes. In addition, HrHEMA-, HrPOR- and HrCAO-overexpressing tobacco plants were made to verify the genes function. Changes of transgenic tobacco were recorded under 2000 lx, 6000 lx and 10,000 lx light intensity. Additionally, the contents of enzyme 5-aminolevulinic acid (5-ALA), porphobilinogen (PBG), chlorophyll a and b (Chla and Chlb), carotenoid (Cxc), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), proline (Pro) and catalase (CAT) under different light intensities were evaluated. Results The silencing of HrHEMA, HrPOR and HrCAO genes can induce leaf yellowing and chloroplast structure changes in Hosta. Specifically, leaves of Hosta with HrCAO silencing were the most affected, while those with HrPOR silencing were the least affected. Moreover, all three genes in tobacco were highly expressed, whereas no expression was detected in wild-type (WT). However, the sensitivities of the three genes to different light intensities were different. The highest expression level of HrHEMA and HrPOR was detected under 10,000 lx of illumination, while HrCAO showed the highest expression level under 6000 lx. Lastly, the 5-ALA, Chla, Cxc, SOD, POD, MDA, Pro and CAT contents in different transgenic tobaccos changed significantly under different light intensities. Conclusion The overexpression of these three genes in tobacco enhanced photosynthesis by accumulating chlorophyll content, but the influential level varied under different light intensities. Furthermore, HrHEMA-, HrPOR- and HrCAO- overexpressing in tobacco can enhance the antioxidant capacity of plants to cope with stress under higher light intensity. However, under lower light intensity, the antioxidant capacity was declined in HrHEMA-, HrPOR- and HrCAO- overexpressing tobaccos.

EFFECTS OF PSYCHOLOGICAL STRESS, ACUTE COLD STRESS, AND DIET ON FORESTOMACH CONTRACTIONS IN CATTLE

1988 ◽  
Vol 68 (2) ◽  
pp. 399-407 ◽  
Author(s):  
A. LIRETTE ◽  
J. M. KELLY ◽  
L. P. MILLIGAN ◽  
R. J. CHRISTOPHERSON
Keyword(s):  
Heart Rate ◽  
Cold Stress ◽  
Key Words ◽  
Psychological Stress ◽  
Latin Square ◽  
Alfalfa Hay ◽  
Alfalfa Silage ◽  
Acute Psychological Stress ◽  
Key Words Cold

Studies were made on forestomach contraction frequencies as affected by diet (brome hay, alfalfa hay, alfalfa silage and barley concentrate diet), acute cold stress and acute psychological stress. Four 15-mo-old steers fitted with ruminal fistulae were used in a 4 × 4 Latin square design. Diets did not influence contractile frequencies of the forestomachs, and did not interact with the effects of the stresses. Acute cold stress and psychological stress both produced significant increases of forestomach contraction frequencies and of heart rate. Key words: Cold stress, psychological stress, forestomach contractions, heart rate

A laboratory study of vertical migration

1955 ◽  
Vol 144 (916) ◽  
pp. 329-354 ◽  
Keyword(s):  
Light Intensity ◽  
Vertical Migration ◽  
Time Course ◽  
Tap Water ◽  
Low Light ◽  
Overhead Light ◽  
Light Intensities ◽  
Orientation Response ◽  
Reduced Light ◽  
Characteristic Maximum

In a tank filled with a suspension of indian ink in tap water, a population of Daphnia magna will undergo a complete cycle of vertical migration when an overhead light source is cycli­cally varied in intensity. A ‘dawn rise’ to the surface at low intensity is followed by the descent of the animals to a characteristic maximum depth. The animals rise to the surface again as the light decreases, and finally show a typical midnight sinking. The light intensities at the level of the animals in this experiment are of the same order as those which have been reported in field observations; the time course of the movement also repeats the natural conditions in the field. The process is independent of the duration of the cycle and is related only to the variation in overhead light intensity. At low light intensity the movement of the animal is determined solely by positive photo-kinesis; the dawn rise is a manifestation of this, and is independent of the direction of the light. At high light intensities there is an orientation response which is superimposed upon an alternating positive (photokinetic) phase and a negative phase during which movement is inhibited. The fully oriented animal shows a special type of positive and negative phototaxis, moving towards the light at reduced light intensities and away from it when the light intensity is increased. In this condition it follows a zone of optimum light intensity with some exactness. Experiments show that an animal in this fully oriented condition will respond to the slow changes of intensity characteristic of the diurnal cycle, while being little affected by tran­sient changes of considerable magnitude.

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