Investigation of the effects of constant darkness and light on blood serum cholesterol, insulin and glucose levels in healthy male rats

This study was designed to investigate the effects of constant darkness and light on changes of serum cholesterol, insulin and glucose levels in healthy male rats. In this study, healthy male rats (n = 30) were divided into 3 groups of tens and kept at various light/dark conditions: Control 12:12 light/dark (LD); constant darkness (DD), and constant light (LL) groups for 2 weeks. Blood samples were obtained from retro-orbital sinus before start of experiment and on the 7th and 14th days of the experimental period. The serum cholesterol and glucose levels were measured by the enzymatic method and insulin levels were measured using insulin kit by enzyme-linked immunosorbent assay (ELISA) method. The results of the study showed that the levels of serum cholesterol and glucose on the 7th and 14th days of the experimental period in DD group significantly decreased compared to the LD and LL groups (p < 0.05). On the 14th day of experiment, we observed significant decrease of serum insulin level in the constant darkness group compared with the two other groups (p < 0.05). The study showed that on the 7th and 14th days of experiment, constant light significantly increased serum glucose level without having any significant effects on serum cholesterol and insulin levels. Also, the long period of time (14 days) was found to be more effective in the serum of these metabolic parameters changes than the short period (7 days).Key words: Constant darkness, light, cholesterol, glucose, insulin, healthy male rats

Circadian clocks and life-history related traits: is pupation height affected by circadian organization in Drosophila melanogaster?

In D. melanogaster, the observation of greater pupation height under constant darkness than under constant light has been explained by the hypothesis that light has an inhibitory effect on larval wandering behaviour, preventing larvae from crawling higher up the walls of culture vials prior to pupation. If this is the only role of light in affecting pupation height, then various light : dark regimes would be predicted to yield pupation heights intermediate between those seen in constant light and constant darkness. We tested this hypothesis by measuring pupation height under various light : dark regimes in four laboratory populations ofDrosophila melanogaster. Pupation height was the greatest in constant darkness, intermediate in constant light, and the least in a light/dark regime of LD 14:14 h. The results clearly suggest that there is more to light regime effects on pupation height than mere behavioural inhibition of wandering larvae, and that circadian organization may play some role in determining pupation height, although the details of this role are not yet clear. We briefly discuss these results in the context of the possible involvement of circadian clocks in life-history evolution

Effect of melatonin on the activity of marker enzymes in the neuronal plasmatic membranes under conditions of acute hypoxia and varying photoperiodic duration

The effect of a single-shot intraperitoneally administration of melatonin in a dose of 1 mg/kg on the activity of Na+, K+ATPase and 5'nucleotidase (5'N) in the forebrain of juvenile male white rats has been investigated under conditions of acute hypoxia. Such studies have been carried out against a background of a varying duration of the photoperiod during one week. It has been established that constant darkness prevents an inhibition of the activity of Na+, K+ ATPase caused by acute hypoxia inducing and promoting an activation of 5'N. The administration of melatonin likewise constant darkness against a background of acute hypoxia prevents a decrease of the activity of Na+, K+ATPase and increases the activity of 5'N

Transcriptional Structure of Petunia Clock in Leaves and Petals

The plant circadian clock coordinates environmental signals with internal processes including secondary metabolism, growth, flowering, and volatile emission. Plant tissues are specialized in different functions, and petals conceal the sexual organs while attracting pollinators. Here we analyzed the transcriptional structure of the petunia (Petunia x hybrida) circadian clock in leaves and petals. We recorded the expression of 13 clock genes in petunia under light:dark (LD) and constant darkness (DD). Under light:dark conditions, clock genes reached maximum expression during the light phase in leaves and the dark period in petals. Under free running conditions of constant darkness, maximum expression was delayed, especially in petals. Interestingly, the rhythmic expression pattern of PhLHY persisted in leaves and petals in LD and DD. Gene expression variability differed among leaves and petals, time of day and photoperiod. The transcriptional noise was higher especially in leaves under constant darkness. We found that PhPRR7, PhPRR5, and PhGI paralogs showed changes in gene structure including exon number and deletions of CCT domain of the PRR family. Our results revealed that petunia petals presented a specialized clock.This work was developed under projects Fundación Séneca 19398/PI/14, MICINN-FEDER BFU-2013-45148-R and BFU-2017-88300-C2-1-R

Deep- Sea Bacteria And Their Biotechnological Potentials

Deep-sea environment characterized by its low temperature, high hydrostatic pressure, limited nutrient contents, and constant darkness has been a hostile environment for most marine microorganisms. Therefore it is a home for low temperature and high pressure-loving bacteria believed to functionally over shallow water intruders. Deep-sea has been regarded as rainforests in terms of their microbial diversity. Thus, the deep-sea should commend itself to microbiologists and biotechnologists alike as source of novel microorganisms and exploitable properties. Near Indonesia several deep-sea trenches exist with diverse environmental conditions. However, up to now there has been no effort to study the microbial communities of those deep-sea environments by Indonesian scientists. This is mainly because of the lack of knowledge in the field of deep-sea microbiology in Indonesia

Circadian Fluctuations Of Period Protein Immunoreactivity In The CNS And Visual System Of Drosophila

When the protein encoded by the period (per) gene, which influences circadian rhythms in Drosophila melanogaster, was labeled with an anti- per antibody in adult flies sectioned at different times of day, regular fluctuations in the intensity of immunoreactivity were observed in cells of the visual system and central brain. These fluctuations persisted in constant darkness. Time courses of the changing levels of staining were altered in the per-short mutant: in light/dark cycles, the phase was earlier than in wild-type, and in constant darkness the period was shorter. In a per-long mutant and in behaviorally subnormal germline transformants (involving transduced per DNA), staining intensities were much fainter than in wild-type. Factors involved in initiating or maintaining the per protein cycling were investigated by examining the immunoreactivity in visual system mutants and by exposing wild-type flies to altered light/dark regimes. These genetic and environmental manipulations affected the expression of the per protein in ways that usually parallelled their effects on circadian behaviors

Morph-associated JH titer diel rhythm in \u3ci\u3eGryllus firmus\u3c/i\u3e: Experimental verification of its circadian basis and cycle characterization in artificially selected lines raised in the field

Previous studies demonstrated a high-amplitude, diel cycle for the hemolymph JH titer in the wing-polymorphic cricket, Gryllus firmus. The JH titer rose and fell in the flight-capable morph (long-winged, LW(f)) above and below the relatively temporally invariant JH titer in the flightless (short-winged, SW) morph. The morph-specific JH titer cycle appeared to be primarily driven by a morph-specific diel cycle in the rate of JH biosynthesis. In the present study, cycles of the JH titer and rate of JH biosynthesis in the LW(f) morph persisted in the laboratory under constant darkness with an approximate 24 h periodicity. The JH titer cycle also shifted in concert with a shift in the onset of the scotophase, was temperature compensated in constant darkness, and became arrhythmic under constant light. These results provide strong support for the circadian basis of the morph-specific diel rhythm of the JH titer and JH biosynthetic rate. Persistence of the JH titer cycle under constant darkness in multiple LW-selected and SW-selected stocks also provides support for the genetic basis of the morph-associated circadian rhythm. The morph-specific JH titer cycle was observed in these stocks raised in the field, in both males and females, in each of 3 years studied. The onset of the cycle in the LW(f) morph, a few hours before sunset, correlated well with the onset of the cycle, a few hours before lights-off, in the laboratory. The morph-specific JH titer cycle is a general feature of G. firmus, under a variety of environmental conditions, and is not an artifact of specific laboratory conditions or specific genetic stocks. It is a powerful experimental model to investigate the mechanisms underlying endocrine circadian rhythms, their evolution, and their impact on life history evolution