Light and temperature affect retinyl ester hydrolase activity and visual pigment composition

Dim light, in combination with high water temperature, resulted in a significant increase in the retinyl ester hydrolase activity in the goldfish retina. This rise in enzyme activity may relate to a selective increase in the availability of retinal chromophores thereby favoring the formation of rhodopsin under these light and temperature conditions.     

Structures and molecules involved in generation and regulation of biological rhythms in vertebrates and invertebrates

Melatonin from the retina and the pineal gland functions in neuroendocrine hierarchies. Photoreceptors — eyes and extraretinal — detect light. Oscillators — pineal and suprachiasmatic nuclei — act as pacemakers. Driven neuroendocrine rhythms carry temporal hormone signals throughout the body. Light controls melatonin: light sets the phase of the melatonin rhythm and determines the duration of melatonin synthesis. By these means, circadian rhythms (e.g. in locomotor activity and body temperature) and seasonal rhythms (e.g. in reproduction) are controlled.     

Aktivitätsuntersuchungen bei Fransenfledermäusen (Myotis nattereri,Kuhl 1818)

Summary Field experiments on the diurnal activity of Natterer's bat (Myotis nattereri, Kuhl 1818) are described. The diurnal activity pattern follows the course of the light intensity with a phase difference. This phase difference and certain details of the activity pattern are subject to seasonal changes and are influenced by the ambient temperature.     

Long-term motor activity recording of dogs and the effect of sleep deprivation

Summary Motor activity of laboratory dogs was recorded for several weeks with an ambulatory monitoring device. The effect of 24 h sleep deprivation (SD) on motor activity during recovery was investigated. A clear rest-activity rhythm was established. The dogs exhibited a similar mean daily rest-activity pattern: 1) rest occurred mainly in the dark; 2) the amimals were most active after light onset; activity increased during the last two dark hours; 3) a rest period was found at noon and reduced activity during afternoon hours. There was a marked difference in total activity between individual dogs. Activity patterns varied as a function of the day of the week; this may have been a reflection of variations in the level of human activities in the laboratory. There was a significant reduction of motor activity during the 24-h period following SD. This was particularly evident in the first 6 h of the light period immediately following the deprivation.In addition, there was a significant increase in the number of episodes with activity 5 counts during recovery. The study confirms the possibility of measuring motor activity to assess compensatory mechanisms during recovery after SD. Sleep regulation, therefore, does not necessarily need to be exclusively examined by the invasive technique of EEG registration.     

Induction of cyst formation by low temperature in the dinoflagellateGonyaulax polyedra Stein: Dependence on circadian phase and requirement of light

Encystment, which at a temperature of 15°C is photoperiodically controlled inGonyaulax polyedra, can also be induced by a decrease of temperature, from 20 to 10 or 8°C in the absence of photoperiodic signals. The cyst-inducing capacity of the decrease in temperature depends on the circadian phase: in constant light, the maximum of sensitivity was found at the beginning of subjective night. In a light/dark cycle, however, cyst formation was reduced during dark phase, indicating that light is required for the process of encystment. A similar light dependence was seen in the effect of the physiologically occurring cyst inducer 5-methoxytryptamine, but not in the encystment response to the protonophores monensin and nigericin.     

Stress-induced photon emission from perturbed organisms.

This paper reviews an ultraweak luminescent response of selected biological systems (lower and higher plants, insects and spermatozoa) to certain kinds of detrimental mechanical, temperature, chemical and photochemical stress and to lethal factors. The enhancing effect of white light and formaldehyde on the ultraweak luminescence of yeast and spermatozoa cells is described for the first time. An increase in the percentage of long wavelengths (lambda > 600 nm) with an increase in reaction time, and a significant influence of the suspending medium on the ultraweak luminescence, were observed. The vitality and motility of bull spermatozoa and the vitality of yeast cells were drastically decreased by treatment with white light, water, formaldehyde and iron-ions. Successive irradiation of intact bull spermatozoa cells with white light caused an increase in the intensity of delayed luminescence. An attempt has been undertaken to find stochastic models of non-stationary photon emission. The quasi-relaxation descending stage of non-stationary processes can be modeled as the Integrated Moving Average process IMA (0, 1, 1), and memory and transfer functions can describe the degree of perturbation in the yeast Saccharomyces cerevisiae. The relation of the ultraweak luminescence response to perturbations of homeostasis is discussed in the framework of biochemical and physical models.     

Stress-induced photon emission from perturbed organisms

This paper reviews an ultraweak luminescent response of selected biological systems (lower and higher plants, insects and spermatozoa) to certain kinds of detrimental mechanical, temperature, chemical and photochemical stress and to lethal factors. The enhancing effect of white light and formaldehyde on the ultraweak luminescence of yeast and spermatozoa cells is described for the first time. An increase in the percentage of long wavelengths (λ>600 nm) with an increase in reaction time, and a significant influence of the suspending medium on the ultraweak luminescence, were observed. The vitality and motility of bull spermatozoa and the vitality of yeast cells were drastically decreased by treatment with white light, water, formaldehyde and iron-ions. Successive irradiation of intact bull spermatozoa cells with white light caused an increase in the intensity of delayed luminescence. An attempt has been undertaken to find stochastic models of non-stationary photon emission. The quasi-relaxation descending stage of non-stationary processes can be modeled as the Integrated Moving Average process IMA (0,1,1), and memory and transfer functions can describe the degree of perturbation in the yeastSaccharomyces cerevisiae. The relation of the ultraweak luminescence response to perturbations of homeostasis is discussed in the framework of biochemical and physical models.     

Induction of cyst formation by low temperature in the dinoflagellate<Emphasis Type="Italic">Gonyaulax polyedra</Emphasis> Stein: Dependence on circadian phase and requirement of light

Encystment, which at a temperature of 15°C is photoperiodically controlled inGonyaulax polyedra, can also be induced by a decrease of temperature, from 20 to 10 or 8°C in the absence of photoperiodic signals. The cyst-inducing capacity of the decrease in temperature depends on the circadian phase: in constant light, the maximum of sensitivity was found at the beginning of subjective night. In a light/dark cycle, however, cyst formation was reduced during dark phase, indicating that light is required for the process of encystment. A similar light dependence was seen in the effect of the physiologically occurring cyst inducer 5-methoxytryptamine, but not in the encystment response to the protonophores monensin and nigericin.     

Adenyl cyclase activity at different environmental temperatures in the isolated rat anterior pituitary membranes.

The effect of different environmental temperatures on adenyl cyclase was studied. An increase in temperature appears to increase TRH-induced activity of adenyl cyclase, and possible causes an increases sensitivity to the hormone. Cyclic AMP levels of the pituitaries showed change at different environmental temperatures.     

Adenyl cyclase activity at different environmental temperatures in the isolated rat anterior pituitary membranes

Summary The effect of different environmental temperatures on adenyl cyclase was studied. An increase in temperature appears to increase TRH-induced activity of adenyl cyclase, and possibly causes an increased sensitivity to the hormone. Cyclic AMP levels of the pituitaries showed change at different environmental temperatures.     

Effect of light on variations in blood testosterone in the ram: demonstration of a photosensitive phase in diurnal rhythm]

6 groups each of 5 adult rams were subjected in light controlled pens to a pretreatment of normal variations in daylength during May and June. Then one group followed the normal daylength and the other five different "skeleton photoperiods" of 8 hrs of light per day consisting of: 7 hrs continuous light (7 L) + 1 hr light (1 L) situated at different times of the dark period (D) according to groups. Blood samples were taken once each week and hourly during one 24 hr period in June, July and September. Peripheral plasma testosterone measured by radio-immunoassay was used as an index of testicular activity. There was increase in the level of testosterone resuting from a rise in the number of peak release during the 24 hrs. In the different light treatments tested, only the treatment (7L+9D+1L)+7D) stimulated testosterone secretion with the pattern of testosterone of this group being similar to that of the control group. This indicates that there exists a photosensitive phase at 16 to 17 hrs after the beginning of the principal light (the subjective dawn).     

Pineal indols and testosterone affect exploratory activity of male rats

Summary The testosterone level has an inverse relation to activity in the open-field test. This is more important in red light than in white light. Pineal indols do not disturb this action. Some of these results are consistent with the assumption that androgens play a role on the exploratory activity of adult subjects.     

Pineal indols and testosterone affect exploratory activity of male rats

The testosterone level has an inverse relation to activity in the open-field test. This is more important in red light than in white light. Pineal indols do not disturb this action. Some of these results are consistent with the assumption that androgens play a role on the exploratory activity of adult subjects.     

Light dependent accumulation of macrophages at the photoreceptor-pigment epithelial interface in the retina of albino mice

Summary In the subretinal space of albino mice, macrophages appear from the time of eye opening and increase in number for 6 months; thereafter they decline with age. Dark rearing retards the accumulation of these cells, and exposure to constant light results in a rapid increase. Observations suggest that macrophages appear as a response to visual cell decay in albino mice and supplement the phagocytic activity of the pigment epithelium.We thank R.K. Hawkins for efficient management of the animal colony, H.G. Jansen for cooperation in the use of electron microscope and Ms Paula van Alphen for help in preparation of the illustrations.     

Plotinus’s conception of unity and multiplicity as the root to the medieval distinction between lux and lumen

Plotinus resolved the paradox of the immanent transcendence, characterizing the relation between the One and the universe, through his theory of the two energeiai. According to this doctrine, all existents have an internal activity and an external activity: the internal activity comprises the true essence and substance of each being; the external activity is emitted outwards as its image. The source of the emission is thus present in the lower layer of being by virtue of its manifold images. The prominence given to light in elucidating this solution led to a distinction between two types of lights: an original light, corresponding to the internal energeia of every existent, and a secondary light, which is the outflow and image of the first light, existing outside of the luminous body.This paper demonstrates the striking similarity between these two Plotinian lights and the concepts of lux and lumen developed by two thirteenth-century philosophers: Robert Grosseteste and Albertus Magnus. Moreover, the paper contends that the purpose of these two medieval concepts of light was identical to what Plotinus had in mind when he first made the distinction: to account for the relation between the one and the many.     

Tsetse fly reactions to light and humidity gradients

Tsetse flies are positively phototactic below about 30 degree C and negatively phototactic above it. The flies show a preference for the wet end of a humidity gradient and the bright end of a dorsal light intensity gradient. Studies of activity levels indicate that tsetse flies should aggregate in damp situations where the activity levels is minimal, whereas in practice the flies are distributed throughout the whole of gradient. Analyses of the water and fat content of experimental flies indicates that the reactions of individual flies is determined by their physiological condition and the conditions under which the flies have previously been kept. Previous ecological studies on the reactions of flies to humidity and light stimuli need to be reassessed in the light of these findings.     

The potential significance of microbial activity in radioactive waste disposal

Summary Active microorganisms can exist in any proposed environment if the basic requirements for life are satisfied, i.e. a suitable temperature and pH, the presence of the necessary nutrients and water. If conditions are not favourable microbes may survive in a dormant state until a change will allow activity. In local pockets microenvironments may become established where microbial activity may increase leading to altered environmental conditions and to changes in the near-field, e.g. degradation and breakdown of barriers, gas generation and/or uptake and transport of nuclides.     

Tsetse fly reactions to light and humidity gradients

Summary Tsetse flies are positively phototactic below about 30°C and negatively phototactic above it. The flies show a preference for the wet end of a humidity gradient and the bright end of a dorsal light intensity gradient. Studies of activity levels indicate that tsetse flies should aggregate in damp situations where the activity level is minimal, whereas in practice the flies are distributed throughout the whole of a gradient. Analyses of the water and fat content of experimental flies indicates that the reactions of individual flies is determined by their physiological condition and the conditions under which the flies have previously been kept. Previous ecological studies on the reactions of flies to humidity and light stimuli need to be reassessed in the light of these findings.     

Effects of sham-pinealectomy,performed under white and red light,on the melatonin content of rat pineal glands

Summary Sham-pinealectomy, performed under different light conditions in newborn and adult rats, is followed by changes of pineal activity resulting in variations of melatonin content. The pineal glands of rats sham-operated under white light produce significantly less melatonin. In contrast, glands of rats operated on under red light show a melatonin content corresponding to that of intact rats. This result implies that normal white light causes a disturbance in melatonin production by a non-retinal pathway.     

Trypsin activity in the hepatopancreas ofMacrobrachium lamarrei (Crustacea: Decapoda)

Summary Trypsin from the hepatopancreas ofMacrobrachium lamarrei showed optimum activity at pH 7.5 and temperature 45°C. The enzyme activity increased with the increase in incubation period and enzyme concentration. Michaelis constant of the enzyme was 2.38×10^–2 M.Acknowledgments. The authors are thankful to University Grants Commission, India for the award of a Junior Research Fellowship.