Erg circadian rhythm in the course of ontogeny in crayfish

• 1.1. The objective of the present work was to study the ontogeny of the ERG circadian rhythm in crayfish.
• 2.2. Long-term recordings of ERG and shielding retinal pigments position measured from the instar, the second instar, the third instar and the adult crayfish were obtained.
• 3.3. In the youngest animals (1–8 days old) an ultradian rhythm (15min-4hr periods) in the ERG amplitude was detected.
• 4.4. Older animals showed a progressive increment in the period length before they exhibited a circadian pattern. This last appeared, the first time, in 30-day-old animals and showed noticeable differences in the adult crayfish. At the same time, the crayfish began to show photomotor reflex. Later on (140-day-old crayfish) the circadian rhythm attained its final parameters.
• 5.5. The SD was used as a measure of lability in periods. The 4 hr ultradian rhythm and the 22.4 hr circadian rhythm showed the lowest SD indicating that they are the most precise period values.
• 6.6. Our results support the idea that the ERG circadian rhythm results from the coupling among high frequency (ultradian) oscillators, particularly those of 4 hr periods and that the coupling depends on the action of neurosecretions released from the sinus gland.

     

Effect of polarized light on the ERG circadian rhythm in crayfish

• 1.1. Crayfish subjected to constant darkness and temperature displayed an electroretinographic circadian rhythm with both non-polarized and polarized light stimuli.
• 2.2. In the ERG circadian rhythm associated with polarized light there was an observed reduction in period and increment in both amplitude and activity: rest ratio.
• 3.3. The change from non-polarized to polarized light also produced phase advances or delays in the ERG circadian rhythm depending on the circadian time when the change was introduced.
• 4.4. Separate recording of HI and HII ERG components showed that HII is always less conspicuous and more easily saturable than HI circadian rhythm.
• 5.5. These results support that: (a) the detection of polarized light contributes to extend the differences between night and day; (b) the two structures involved in the generation of HI and HII ERG components, i.e. the rhabdom and the retinular cell, operate as two independent elements of the circadian system responsible of ERG circadian rhythm.

     

The development of thermoregulation in the marsupial brushtail possum Trichosurus vulpecula

• 1.1. The adult possums showed a circadian rhythm of body temperature with a peak in temperature around midnight and a nadir at noon.
• 2.2. The young possum within the pouch displayed a circadian rhythm with the highest temperatures during the day and the lowest in the early evening.
• 3.3. Although the body temperature of the young possum exceeded that of the mother occasionally, for the major part of the 24 hr the body temperature of the young was lower than that of the mother.
• 4.4. The young possum could maintain a steady body temperature between 140 and 167 days post partum. A circadian rhythm of temperature was observed between 157–190 days post partum.
• 5.5. All adipose tissue examined with the light and electron microscope had the morphology of white adipose tissue.

     

Effect of eyestalk ablation on oxygen consumption of callinectes similis exposed to salinity changes

• 1.1. The effect of eyestalk ablation on preadults of Callinectes similis exposed to a constant salinity (30%.) and to simulated tidal changes in salinity (30-11 to 30%.) were measured.
• 2.2. In constant salinity, crabs showed a persistent respiratory rhythm, with a maximum oxygen consumption during the day. Under these conditions, ablation significantly increased the respiratory rate but not the rhythm.
• 3.3. In variable salinities, the highest respiratory rates occurred in salinities of 11 and 16%. during the night. In these crabs, ablation of eyestalks and subsequent injection of eyestalk extracts did not alter the respiration rate rhythm.
• 4.4. The circadian rhythm is controlled by the periodicity of environmental changes instead of the influence of eyestalk hormones.
• 5.5. Regulation of metabolism in C. similis associated with osmoregulation involves other neurosecretory organs.

     

Melatonin: A coupling device between oscillators in the circadian system of the ruin lizard Podarcis sicula

• 1.1. Chronic administration of melatonin (in silastic capsules) lengthened the free-running period of the locomotor rhythm and shortened the circadian activity time in Podarcis sicula held in constant temperature and darkness.
• 2.2. Lizards displaying a bimodal pattern of activity invariably became unimodal after melatonin administration.
• 3.3. The results support the hypothesis that melatonin acts as a coupling device between circadian oscillators driving the locomotor rhythm in Podarcis sicula.

     

Assimilation efficiency in birds: A function of taxon or food type?

• 1.1. We review the available measurements of assimilation efficiency in birds and find a strong dependence upon food ingested, regardless of bird taxa.
• 2.2. Assimilation efficiency in birds is about 75% for most food types, except plants (36.9%) and fruits (41%).

     

Circadian organization in white suckers Catostomus commersoni: The role of the pineal organ

• 1.1. Pinealectomy of the white sucker, Catostomus commersoni, had significant effects on the free-running circadian rhythm of locomotor activity. With fish kept under constant darkness pinealectomy resulted in a significant alteration in period length and decrease in the precision of circadian activity.
• 2.2. In a number of cases circadian activity was split into two components that free-ran independently.
• 3.3. The pineal organ is suggested to function in the coupling of a multi-oscillator system making up circadian organization in this fish.

     

Analysis of postembryonic development of locomotor activity rhythm by corpora allata implantation in the cricket gryllus bimaculatus

• 1.1. Male crickets Gryllus bimaculatus show a drastic change in circadian rhythm from nymphal diurnality to adult nocturnality, in association with an increase in activity level several days after the imaginai moult.
• 2.2. The corpora allata implantation into male 7th or 8th instar nymphs produced supernumerary instar nymphs in about 30% of the implanted animals, but did not affected the normal development in the remaining animals.
• 3.3. The majority of the supernumerary instar nymphs were diurnal and sexually inactive, although their internal reproductive organs appeared to be fully mature.
• 4.4. The supernumerary instar nymphs became nocturnal with an increase in activity level several days after the imaginai (9th) moult.
• 5.5. The roles of the nervous system in the regulation of the rhythm reversal are discussed.

     

Effects of long-term food restriction on energy expenditure and thermoregulation in broiler-breeder fowls (Gallus domesticus)

• 1.1. From 2 to 21 weeks of age, 150 female broiler-breeder chicks received one of three dietary treatments. Fifty received an ad libitum supply of food (treatment AL). The remaining 100 were given weighed (restricted) rations once a day, 50 receiving the amount per bird recommended in the Ross 1 Parent Stock Management Manual (treatment R) and the other 50 receiving twice this recommended amount (treatment 2R). Water was provided ad libitum for all treatment groups.
• 2.2. The daily allowance for R birds increased from 26 g per bird at 2 weeks of age to 94 g at 21 weeks. The intake of AL birds meanwhile increased from 65 g at 2 weeks to 240 g at 19 weeks, before decreasing to about 200 g at 21 weeks.
• 3.3. Median heat productions (H) per bird in the R and 2R treatment groups were, respectively, 65 and 40% lower than in the AL when adjustment was made for the reduced food intake of AL birds in the calorimeter chambers. The effects of dietary treatment on fasting H were proportionally similar.
• 4.4. Because the increasing divergence in body weights would have made a large contribution to differences in H per bird, the results were adjusted to the median weight of 2.03 kg and to unit weight (1.00kg). Adjusted fasting heat production was 18 and 11% less in 2R and R birds than in those fed ad libitum.
• 5.5. If age was included as a variate in the logarithmic multiple regression, H was proportional to body weight (W, kg) raised to the power 0.73; if age was not included, H was proportional to W^0.55.
• 6.6. Rectal temperature was 0.7°C higher in AL birds at ambient temperatures of both 23 and 28°C. All treatment groups had a higher rectal temperature at 28°C than at 23°C, with the AL birds most affected.
• 7.7. Foot surface temperature of R birds at an ambient temperature of 23°C was 8°C lower than that of the 2R and AL groups, indicating peripheral vasoconstriction.
• 8.8. Polypnea (panting) and wing-extension occurred frequently in the AL birds, which also had a greater water intake. It was also observed that the restricted birds tended to aggregate, while the AL groups tended to space themselves evenly about the pen.
• 9.9. It was concluded that broiler breeder fowl responded to restricted food intake by a reduction in heat production over and above that resulting directly from reduced metabolism of food and reduced body weight. The reduced metabolic rate per unit of weight conferred a thermoregulatory advantage at high ambient temperature.

     

Laboratory studies on the oxygen consumption of the marine teleost,Lichia amia (Linnaeus, 1758)

• 1.1. The oxygen consumption of the marine teleost, Lichia amia was investigated under controlled laboratory conditions.
• 2.2. The routine oxygen consumption showed a strong circadian rhythm with the fish being mainly active during the light period.
• 3.3. The specific mass exponent (dimension: μg O₂/g/hr) is temperature independent and ranges from 0.27–0.29.
• 4.4. Starving the fish results in a mean decrease in active, routine and standard oxygen consumption of 21%, 24% and 20%, respectively.
• 5.5. Feecling led to an increase in the oxygen consumption of the teleosts, with the mean metabolic rate over the 24 hr that followed, being 58% and 50% higher for fish that had been starved for 162hr and 40 hr, respectively.
• 6.6. Apparent SDA showed some variation and ranged from 6.0 to 35.5%.
• 7.7. The results obtained are generally in agreement with those recorded for other teleosts.

     

Analysis of the circadian rhythm in energy metabolism of rat liver

• 1.1. To study the temporal organization of energy metabolism in rat liver the steady state concentrations of key intermediates of carbohydrate and phosphorus metabolism were determined during 24 hr.
• 2.2. The circadian rhythm in energy metabolism of rat liver has been analysed by four different approaches. It was shown that neither apparent PEP synthesis nor crossover theorem were acceptable for the elucidation of the temporal organization of multi-enzyme systems.
• 3.3. Correlations analysis explained the temporal organization of energy metabolism most satisfactorily.
• 4.4. Based on the results of this analysis it was suggested that circadian regulation of energy metabolism in liver was realized at the level of the citric acid cycle.

     

The optic nerve mediates the circadian pigment migration in the median eyes of the scorpion

• 1.1. The peripheral visual pathway from the median eyes of the scorpion Androctonus australis was interrupted at different points and the effect on the circadian rhythm of median-eye sensitivity was examined.
• 2.2. Any interruption of the visual pathway distal to the supraesophageal ganglion abolishes the circadian sensitivity rhythm in the median eyes. This rhythm is thus controlled by efferents in the optic nerve (very probably via the neurosecretory axons) rather than by way of the hemolymph.
• 3.3. Following transection of the optic nerve, the sensitivity of the median eyes proceeds rapidly to the daytime state. This condition is associated with movement of the screening pigment into the distal ends of the visual cells.
• 4.4. The oscillator system controlling the circadian pigment migration in the median eye cannot be located in the eye itself, but must lie in the CNS, proximal to the first optic ganglion. The oscillator itself need not be connected to both median eyes in order to function normally, as revealed by the continued rhythm in the contralateral eye following unilateral optic nerve section.

     

Human-induced tachycardia in wild and tame mallard (Anas platyrhynchos)

• 1.1. The effect of regular handling on fear reactions was investigated in mallard (Anas platyrhynchos) by exposing six hand-reared and four wild ducks to an approaching human being and recording heart rates with an external ECG device.
• 2.2. All ducks reacted to the approach with tachycardia, but the response was significantly less in tame birds.
• 3.3. Hand-reared females showed less response than males. No sex-linked differences were apparent in the wild ducks.
• 4.4. Decreasing responses throughout the experiments were only found in tame birds.
• 5.5. Fear or stress reactions can apparently be diminished through habituation induced by regular handling.

     

Functional maturation of the salt gland of the goose

• 1.1. Experiments were carried out to determine the influence of age on salt gland secretion in the domestic goose.
• 2.2. Oral or i.v. loading of hypertonic NaCl evoked a rapid secretory response in geese 6–14 weeks of age.
• 3.3. A significantly smaller fraction of the salt load was secreted by older birds (2.2 kg and above) than by younger birds (< 2.2 kg).
• 4.4. The maximum volume collected and the maximum sodium concentration during an 80 min observation period did not differ over a range of < 1 kg to > 4 kg in body weight.
• 5.5. The maximum volume and sodium concentration/kg of body weight decreased significantly as the birds aged.
• 6.6. A greater fraction of the administered water load was secreted by the salt gland at any time period compared to the fraction of the salt load secreted, indicating substantial cloacal excretion of the salt load.

     

Hematology and blood chemistry of the marsh harrier (Circus aeruginosus)

• 1.1. This study deals with the hematological and blood chemistry of 13 adult marsh harriers (Circus aeruginosus).
• 2.2. No significant differences were observed between male and female groups in any of the parameters.
• 3.3. The value of white blood cells was 14,677/mm³ heterophils and lymphocytes, these being the most abundant cellular type (81.42 and 12%, respectively).
• 4.4. Urea and uric acid are present in approximately similar proportions, though birds are said to be uricotelic.
• 5.5. The cholesterol concentration values determined in our study, are higher than those reported in most other birds.

     

Metabolic and behavioral responses of American kestrels to food deprivation

• 1.1. The effect of short-term (79 hr) food deprivation at 27°C on body mass, locomotor activity, body temperature (T_b), and resting oxygen consumption was determined in eleven American kestrels (Falco sparverius).
• 2.2. The change in body mass during resting followed the relation, % mass remaining = 99 e^{0.07(days fasting)}. There was no significant difference in the rate of relative mass loss between males and females.
• 3.3. Locomotor activity, measured as perch hopping, was highly variable in both control and fasted birds and showed no correlation with stage of the fast, basal metabolic rate (BMR), or rate of mass loss during food deprivation.
• 4.4. Body temperatures of fasted birds declined continuously by 0.2–0.4°C per day from 39.3 to 38.3°C.
• 5.5. Both males and females responded to food deprivation with a decrease in metabolism. By the third night of fasting, BMR had declined 23.4% from 0.845 W (bird day)⁻¹ to 0.647 W (bird day)⁻¹. The observed reduction in BMR is 2.4 times that expected from a 1°C decline in T_b (assuming Q₁₀ = 2.5) indicating active suppression of metabolism.

     

Is the orcadian clock of gonyaulax held stationary after a strong pulse of anisomycin?

• 1.1. Gonyaulax polyedra cells were treated with two sequential pulses of a protein synthesis inhibitor (anisomycin) in order to analyse a possible stopping of the circadian clock by the first pulse.
• 2.2. Inhibition of protein synthesis during these pulses and after centrifugation and resuspension of the cells was determined by measuring the incorporation of labelled amino acids.
• 3.3. The effects of the second pulses on the clock were measured as phase shifts of the glow rhythm with respect to a control rhythm that had been subjected to the initial pulse only.
• 4.4. From the observed phase shifts of the second pulses we conclude that the clock is not stopped by the first pulse but is immediately shifted to a different phase.

     

Sensory and motor innervation of bird intrafusal muscle fibers

• 1.1. Most bird muscle spindles are supplied by only one primary afferent.
• 2.2. Secondary afferents occur irregularly.
• 3.3. Sensory terminals are covered by a basal lamina and a collagenous sheath.
• 4.4. Two types of motor terminal are recognized which can be referred to specific types of intrafusal fiber.
• 5.5. The sensory and motor innervation of bird intrafusal fibers is less understood than that of mammalian intrafusal fibers.

     

Reduction of ferrihemoglobin in erythrocytes of birds and mammals

• 1.1. Species differences exist in ferrihemoglobin reduction rates in bird and mammalian red cells, bird erythrocytes being very active reducers.
• 2.2. Glucose and lactate enhance ferrihemoglobin reduction. In horse and quail red cells β-hydroxybutyrate has this effect as well.
• 3.3. Malate and pyruvate do not enhance ferrihemoglobin reduction.
• 4.4. Plasma addition to red cell suspensions enhances ferrihemoglobin reduction; addition of lactate mimics this effect in all species except the dog.
• 5.5. Incubation conditions are very important for measuring ferrihemoglobin reduction. Especially the presence of bicarbonate ions is essential. In our experiments no inhibition of reduction rates by chloride ions is found.
• 6.6. Mitochondrial NADH production does not play a role in ferrihemoglobin reduction in bird red cells.

     

l-Leucine intestinal transport at different ages in chicken: Effect of anticoccidial drugs

• 1.1. l-Leucine transport by everted slices of duodenum, jejunum ileum and cecum of 1-, 2- and 3-week-old chickens has been determined.
• 2.2. The effects of the administration with the diet of three anticoccidial drugs: monensin, maduromicin ammonium and nicarbazine have been studied.
• 3.3. In the control animals, there is a reduction on intestinal transport with age, except in the duodenum which is not age-dependent.
• 4.4. Momensine induces an increase on leucine transport in the duodenum and cecum at all ages studied and only in the 3-week-old animals in the jejunum and ileum.
• 5.5. Nicarbazine reduces jejunal absorption of leucine and does not affect the function of the other segments.
• 6.6. Maduromicin ammonium has almost no effect on the absorptive process.