Circadian organization in the pigeon,Columba livia: the role of the pineal organ and the eye

Summary The roles of the pineal organ and the eye in the control of circadian locomotor rhythmicity were studied in the pigeon (Columba livia). Neither pinealectomy nor blinding abolished the circadian rhythms in constant dim light conditions (LLdim). All the pinealectomized birds and the blinded birds entrained to light-dark (LD) cycles with no discernible anticipatory activity. However, the birds which had been both pinealectomized and blinded showed no circadian rhythms in prolonged LLdim. These birds entrained to LD cycles with anticipatory activity and showed residual rhythmicity for a while after transfer from LD cycles to LLdim. Continuous administration of melatonin induced suppression of the circadian rhythms and reduced total amount of locomotor activity in LLdim. These results suggest that not only the pineal organ but also the eye (perhaps the retina) is involved in the pigeon's circadian system.Abbreviations NAT N-acetyltransferase - LLdim constant dim light - cadian period - SCN suprachiasmatic nucleus - circadian activity time - LD light-dark     

A continuous migration model with stable demography

A probability model of a population undergoing migration, mutation, and mating in a geographic continuum R is constructed, and an integrodifferential equation is derived for the probability of genetic identity. The equation is solved in one case, and asymptotic analysis done in others. Individuals at x, y R in the model mate with probability V(x, y) dt in any time interval (t, t + dt). In two dimensions, if V(x,y) = V(x–y) where V(x) V(x/)/ ² approaches a delta function, the equilibrium probability of identity vanishes as 0. The asymptotic rate at which this occurs is discussed for mutation rates u u _o > 0 and for Cu , > 0, and u 0.Partially supported by NSF grant MCS79-03472Research was partially supported by Task Agreement No. DE-AT06-76EV71005 under Contract No. DE-AM06-76RL02225 between the U.S. Dept. Energy and the University of Washington     

Effect of Melatonin on the Intensity of Adenosine Production in the Rat Forebrain under Conditions of Acute Hypoxia and Varied Photoperiodicity

We studied the effect of injections of melatonin and modifications of the duration of illumination on the activity of 5-nucleotidase, an enzyme providing synthesis of adenosine, in the forebrain of juvenile male albino rats. The measurements were performed under conditions of acute hypobaric hypoxia. We found that, under conditions of natural illumination, neither isolated injections of melatonin nor acute hypoxia noticeably changed the activity of 5-nucleotidase. At the same time, acute hypoxia combined with melatonin injections increased the activity of this enzyme. A similar noticeable rise in the activity of 5-nucleotidase was observed after melatonin injections in normoxic animals kept in constant darkness, and in rats subjected to hypoxia without the above injections but under conditions of constant illumination. These data allow us to suppose that melatonin (whose level in the extracellular medium is a factor providing synchronization of endogenous temporal rhythms) stimulates 5-nucleotidase-mediated production of adenosine in brain neurons. Acute hypoxia promotes such an effect of melatonin.     

Pinealectomy abolishes the circadian rhythm of migratory restlessness

Summary Pinealectomy of White-throated Sparrows (Zonotrichia albicollis) free-running under constant conditions in dim light abolishes the circadian rhythm of nocturnal spring and fall migratory restlessness (Zugunruhe) as well as the rhythm of summer daytime locomotor activity (Pigs. 1 and 2). Rhythmicity persists in sham-operated birds. Pinealectomized birds are synchronized by a light cycle but their activity rhythm decays to arrhythmicity when they are released from entrainment into constant dim light. The pineal of the white-throat seems essential for the expression of circadian rhythms of both daytime activity and migratory restlessness. These findings support the hypothesis that the avian pineal is fundamentally involved in circadian organization.     

Circadian rhythms of corneal mitotic rate,retinal melatonin and immunoreactive visual pigments,and the effects of melatonin on the rhythms in the Japanese quail

We investigated circadian ocular rhythms in the Japanese quail, Coturnix coturnix japonica. The birds were placed under light-dark cycles (LD 1212), constant light (LL) and constant darkness (DD), and the retinas were dissected out at four-hour intervals throughout 24 h. Following measurements were performed. (1) Melatonin content in the retina was measured by radioimmunoassay. It was low in light and several folds higher in darkness under LD 1212. The rhythm continued in DD, but disappeared in LL. (2) Mitotic figures in the corneal epithelium were counted. Similar rhythms to the melatonin content were observed in the corneal mitotic rate with a slight phase delay. (3) The retinas were fixed at 4-h intervals and immunostained with anti-bovine rhodopsin serum and anti-chicken iodopsin monoclonal antibodies. The outer segments of photoreceptor cells were stained intensively throughout 24 h in LD 1212, LL and DD. In contrast, the stainability of the locus close to the outer limiting membrane where the Golgi apparatus exists changed diurnally. Scores showing the ratio of cells with positive staining indicated high values from 4 h after the onset of light to the beginning of dark phase under LD 1212. The values were high throughout 24 h in LL and intermediate or low in DD. (4) To investigate the effect of melatonin on the corneal mitotic rate and visual pigments at the Golgi region, melatonin was injected into one eye and saline into the contralateral eye. Melatonin induced a phase advance in the corneal mitotic rate under LD 1212, but did not induce a rhythm under LL. The ratio of photoreceptor cells with positive staining to anti-visual pigment antibodies at the Golgi region was not affected by melatonin injection.Abbreviations ANOVA analysis of variance - BSA bovine serum albumin - DD constant darkness - Io-mAb monoclonal antibodies against chicken iodospin - LD light-dark - LL constant light - mRNA messenger ribonucleic acid - PBS phosphate buffer solution - Rh-As antiserum against bovine rhodopsin - SCN suprachiasmatic nucleus - T transducin - T transducin      

Complex circadian regulation of pineal melatonin and wheel-running in Syrian hamsters

Circadian regulation of pineal melatonin content was studied in Syrian hamsters (Mesocricetus auratus), especially melatonin peak width and the temporal correlation to wheel-running activity. Melatonin was measured by radioimmunoassay in glands removed at different circadian times with respect to activity onset (= CT 12). Pineal melatonin peak width (h; for mean 125 pg/gland) and activity duration () were both 4–5 h longer after 12 or 27 weeks than after 5 or 6 days in continuous darkness (DD). Increased peak width was associated with a delay in the morning decline (M) of melatonin to baseline, correlated with a similar delay in wheel-running offset. In contrast, the evening rise (E) in melatonin occurred at approximately the same circadian phase regardless of the length of DD. Fifteen min light pulses produced similar phase-shifts in melatonin and activity. In a phase advance shift, M advanced at once, while E advanced only after several days of adjustment. Independent timing of shifts in the E and M components of the melatonin rhythm suggest that these events are controlled separately by at least two circadian oscillators whose mutual phase relationship determines melatonin peak width. This two-oscillator control of melatonin peak width is integral to the circadian mechanism of hamster photoperiodic time measurement.Abbreviations CT circadian time - DD continuous dark - L: D light: dark cycle - PMEL pineal melatonin - PRC phase response curve - RIA radioimmunoassay; , duration (h) of the active phase of the circadian wheel-running rhythm; , free-running period     

Effect of light-dark cycles with different LD time-ratios and different LD intensity-ratios on the activity rhythm of chaffinches

Summary Chaffinches (Fringilla coelebs L.) were kept at light-dark (LD) cycles with two different light intensity ratios (ca. 500.1 and ca. 101 lux) both with 1.83 hours of twilight at the onset and end of light time. The light time/dark time ratio (LD time-ratio) was varied in the range from 420 to 222 hours.Birds at the high LD intensity-ratio (500.1 lux) increased activity time () with increasing light time from LD 420 to 222. Time of activity onset, middle, and end of activity corresponded to onset, middle, and end of light time from LD 420 to 168, but the phase angles of middle and end of activity (related to midpoint of light time and midpoint of artificial dusk respectively) became more positive (advanced) at LD 204 and 222.Birds at the lower LD intensity-ratio (101 lux) increased activity time with increasing light time from LD 816 to 204 but activity time at LD 420 was equivalent to that at LD 816. The phase angles of activity onset and middle (related to midpoint of artificial dawn and midpoint of light time, respectively) became more positive at both long (LD 204) and short (LD 420) light times.By use of different twilight regimes (linear and logarithmic changes in intensity), it was shown that end of activity was more closely related with the rate of change and/or absolute level of light intensity than was onset of activity.During January and February, the birds responded to increased LD time-ratios by an increase of activity time and by strong positive phase angle shifts which correspond to observations of activity patterns of chaffinches exposed to outdoor conditions during the spring breeding season.The free-running circadian periods () of 6 birds measured at 15 lux at the end of the experiments following LD 204 averaged 22.17 hours.From the data on precision, i. e. the period-to-period variation in the phase angles of single birds averaged over all birds of one group and condition, as well as from the number of birds not synchronized with the LD cycles, it is concluded that extreme long and short light times per 24 h represent weaker zeitgebers compared to LD cycles with medium lengths of light time. Likewise, LD cycles with low LD intensity-ratios are weaker zeitgebers than LD cycles with high LD intensity-ratios.This study was carried out while the senior author was on sabbatical leave from the University of Alaska and held a fellowship from the Alexander von Humboldt Stiftung.     

Seasonal effects on the freerunning rhythm of circadian activity of longnose dace (Rhinichthys cataractae)

Synopsis Freerunning circadian rhythms of locomotor activity in individual longnose dace sampled from a population at 41°N latitude were recorded under constant darkness throughout the year. There was an annual cycle in the length of the circadian period, with maximum and minimum lengths of mean period of 23.6 and 21.6 h recorded during summer (June) and winter (December), respectively. These annual changes in period length may have resulted from seasonal changes in entrainment by natural light-dark cycles and their after-effects on endogenous circadian rhythms. The possibility of an endogenous circannual rhythm was also considered.     

Zur Wirkung des Lichtes auf die circadiane Periodik des Stoffwechsels und der Aktivität beim Buchfinken (Fringilla coelebs L.)

Zusammenfassung Bei 8 Buchfinken (4, 4) wurden Sauerstoffverbrauch und Hüpfaktivitätsowohl unter Bedingungen eines künstlichen Licht-Dunkel-Wechsels (LD 1212 Std; ohne Dämmerung) als auch im Dauerlicht (LL) bei konstanter Umgebungstemperatur (18–20° C) kontinuierlich gemessen. Im 1. Teil des Versuchs wurde die Beleuchtungsstärke während der Dunkelzeit (D) zwischen 0,01 und 1,0 Lux bei gleichbleibender Beleuchtungsstärke während der Lichtzeit (10 Lux) geändert. Im 2. Teil des Versuchs wurden die Vögel im Dauerlicht von 1 und 10 Lux untersucht. Vier Vögel wurden zusätzlich bei 100 Lux gemessen.Das mittlere Niveau des Sauerstoffverbrauchs (pro Std) und die mittlere Aktivitätsmenge (pro Stunde) während einer Periode sind bei der Mehrzahl der untersuchten Vögel linear und positiv miteinander korreliert (Abb. 2 und 3; Tabelle 1).Änderungen des mittleren Aktivitätsumsatzes (Differenz von mittlerem Niveau des Gesamtumsatzes und des Ruheumsatzes) sind ebenfalls positiv mit Änderungen der Aktivitätsmenge korreliert. Diese Aussage beruht auf der Voraussetzung, daß sich die circadiane Periodik des Gesamtstoffwechsels aus mindestens zwei Periodizitäten zusammensetzt: der Periodik des Grundstoffwechsels (vegetative Periodik) und der Periodik von Ruhe und Aktivität (Aktivitätsperiodik).Bei Änderungen des Zeitgebers (Erniedrigung der Zeitgeberamplitude und gleichzeitige Erhöhung der mittleren Beleuchtungsstärke) werden folgende Parameter signifikant verändert: die positive Phasenwinkel-Differenz zwischen Stoffwechselperiodik und Zeitgeber wird vergrößert, die Dauer der Aktivität (Aktivitätsumsatz ₃ ) wird verlängert, die Schwingungsbreite der Stoffwechselperiodik wird erniedrigt (Abb. 4; Tabelle 2).Unter Dauerlicht-Bedingungen werden durch eine Erhöhung der Beleuchtungsstärke von 1 auf 10 Lux folgende circadianen Parameter erhöht: die Frequenz, das mittlere Niveau der Stoffwechselperiodik (Gleichwert), der Ruheumsatz, das -Verhältnis (Verhältnis Aktivitätszeit/Ruhezeit) und die Aktivitätsmenge pro Zeiteinheit. Die Schwingungsbreite der Stoffwechselperiodik bleibt unverändert (Abb. 5). Außerdem besteht eine regelhafte Beziehung zwischen dem Formfaktor der Stoffwechselschwingung und der Beleuchtungsstärke, beziehungsweise der Spontanfrequenz. Erhöhung der Beleuchtungsstärke von 10 auf 100 Lux hat unterschiedliche Wirkungen auf die circadianen Parameter der 4 gemessenen Vögel.Die unter Dauerlicht-Bedingungen gewonnenen Ergebnisse folgen der modifizierten circadianen Regel, die eine positive Korrelation zwischen Frequenz und Gleichwert der autonomen circadianen Schwingung fordert (Abb. 7).Die unter Zeitgeber-Bedingungen (Licht-Dunkel-Wechsel) gewonnenen Ergebnisse werden auf der Grundlage einer vorwiegenden Beeinflussung des circadianen Schwingers durch die Amplitude der Zeitgeber-Periodik (Zeitgeberstärke) gedeutet. Änderungen der Beleuchtungsstärke während der Dunkelzeit (im Bereich der gebotenen Lichtintensitäten) haben keinen regelhaften Einfluß auf die Stoffwechselparameter der Periodik.

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On the effect of light upon the crcadian rhythms of metabolism and activity in the chaffinch (Fringilla coelebs L.)

Summary Oxygen consumption and hopping activity of 8 chaffinches (4 males, 4 females) were measured simultaneously (I) in an artificial 1212 hr light-dark-cycle (LD; without twilight) and (II) in continuous illumination, both at constant temperature (18–20°C). During the first part of the experiment illumination during darktime (D) was varied in both directions between 0.01 and 1.0 lux. Light intensity in L (lighttime) remained constant (10 lux). In the second part of the experiment the birds were exposed to a continuous illumination of 1 and 10 lux. Four birds were also measured at 100 lux.For the majority of the birds, the mean level of oxygen consumption per hour and the average amount of activity (contacts per hour) during one circadian period are positively and linearly correlated to each other (Fig. 2 and 3; Table 1).Changes in the level of the activity metabolism — i.e. the difference between mean level of total metabolism and resting metabolism — are also positively correlated to changes in the amount of activity. This statement is based on the assumption that there exist at least 2 rhythms as basic components of the circadian rhythm of total metabolism: the rhythm of basal metabolic rate (BMR) or vegetative rhythm and the rhythm of activity and rest (activity rhythm).By variation of the Zeitgeber — simultaneous decrease in amplitude and increase in mean level of light intensity — the following parameters are significantly changed: the phase-angle difference between the circadian rhythm of metabolism and the Zeitgeber is increased (positive phase-angle differences are changed in positive direction), the activity time is lengthened, and the amplitude of the rhythm (range of oscillation) is diminished (Fig. 4; Table 2).With an increase in light intensity from 1 to 10 lux (continuous illumination), the following parameters are increased: the frequency of the rhythm, the mean level of metabolism per period, the resting metabolic rate, the -ratio (i.e. ratio activity time/rest time), and the total amount of activity per unit time. The range of oscillation remains unchanged (Fig. 5). There is also a regular change of the form-factor characterizing the shape of the metabolic oscillation, which depends upon light intensity as well as upon frequency (Fig. 8). Increasing light intensity from 10 to 100 lux affected differently the circadian parameters of the four birds tested.The results obtained in continuous illumination follow the modified circadian rule which postulates the positive correlation between frequency and mean level of the autonomous circadian oscillation (Fig. 7).The results obtained under the influence of a Zeitgeber (light-dark-cycle) are interpreted on the basis of the primary influence of the Zeitgeber amplitude (strength of the Zeitgeber) upon the circadian oscillation. The given changes in light intensity during darktime have no significant effect on the metabolic parameters of the rhythm.

     

Unilateral lesions of the hamster suprachiasmatic nuclei: evidence for redundant control of circadian rhythms

Summary Several properties of vertebrate circadian rhythms can be attributed to the behavior of an underlying pacemaker system which is composed of two separate but mutually interacting circadian oscillators. As originally formulated, the model for such a pacemaker system proposed that two oscillators or populations of oscillators have different properties, specifically in their responses to light (Pittendrigh 1974; Pittendrigh and Daan 1976b). We have tested the proposition that the right and left suprachiasmatic nuclei (SCN) of the golden hamster contribute in different ways to the regulation of circadian rhythmicity by measuring the wheel-running activity rhythms of hamsters with lesions to either the right or left SCN. Although effects of unilateral or other partial SCN lesions on pacemaker properties were observed, these effects were not different in hamsters receiving right- or left-side lesions. More specifically: (1) free-running period () in constant light was shorter in lesioned hamsters irrespective of the side lesioned (Fig. 3a), and the total amount of SCN destruction was found to correlate with (Fig. 4). (2) Phase-angle difference () of some lesioned hamsters (both right- and left-side) during entrainment to LD, 1410 was significantly more positive than that of controls (Fig. 3b). (3) The rate of phase-shift following a shift of the light/dark cycle was not different in hamsters with right- or left-side lesions (Fig. 3c). And (4) the simultaneous expression of different circadian periods, similar to splitting, was observed in hamsters with unilateral lesions (Fig. 5). It is concluded that the right and left SCN are similar in their contributions to the control of circadian rhythmicity and that there is as yet no evidence for the permanent loss of multioscillator properties resulting from the destruction of only one of the two SCN.Abbreviations SCN suprachiasmatic nuclei or nucleus - LD light/dark cycle - LL constant light - DD constant dark - circadian period - activity time - rest time - phase angle - phase-angle difference - SD standard deviation - SE standard error - ANOVA analysis of variance     

Ongoing ultradian activity rhythms in the common vole,Microtus arvalis,during deprivations of food,water and rest

Summary The timing mechanism underlying ultradian (2–3 h) activity patterns in the common vole, Microtus arvalis, was studied using behavioural deprivation experiments. These were aimed at distinguishing between a homeostatic control mechanism, in which the rhythmic behaviour itself is part of the causal loop, and a clock mechanism, independent of the behaviour.In 175 experiments, deprivation of food during 3 ultradian cycles in (subjective) daytime did not result in significant changes in the ultradian periodicity of attempts to obtain the food, compared with ad lib. access to food and water. A minor, but significant increase in ultradian activity time () occurred in the course of the deprivation, but this was compensated by a shorter ultradian rest (). These results were obtained both in intact animals (n = 24), which showed ultradian and circadian rhythmicity in behaviour, and in animals (n = 21) with electrolytic lesions aimed at the suprachiasmatic nuclei (SCN), which lacked the circadian modulation of behaviour. Simultaneous deprivation of water and food in 8 voles without circadian rhythmicity during 40 experiments also did not lead to any change in the ultradian periodicity of feeding attempts.Rest deprivation was studied in 5 SCN lesioned voles, by forcing running wheel activity to continue following spontaneous running. Thus, the experimental activity bout was artificially lengthened to 2–9 h in 67 experiments. The onset of the subsequent rest episodes occurred independent of the duration of the preceding . The duration of was dependent on the preceding, experimental in a periodic fashion. The interval experimental (=lengthened +following ) was equal to one, two or three times the control (obtained on nonexperimental days). This result fits the prediction of a clock model and is in conflict with a monotonicincrease of with , as expected in a homeostatic, restorative process.It is concluded that the ultradian timing of activity in the common vole can be explained neither by homeostatic hunger or thirst mechanisms nor by homeostatic rest/activity regulation. The results strongly suggest an independent clock system generating ultradian feeding rhythms in the common vole.Abbreviations DD continuous darkness - LD light-dark regime - LL continuous light - RCA retrochiasmatic area - ARC arcuate nucleus - SCN suprachiasmatic nuclei - ultradian period - ultradian activity time - ultradian rest time     

Yeast Kre1p is a cell surface O-glycoprotein

The Saccharomyces cerevisiae KRE1 gene encodes a secretory protein required for the production of the cell wall polymer (1 6)--glucan. Here we report further characterization of the KRE1 gene product, Krelp. A functional, epitope-tagged Krelp is shown to be highly modified in a SEC53-dependent manner. Krelp is O-glycosylated, but the basis for the majority of its post-translational modification is unknown. Fractionation of Kre1p reveals a cell wall-associated form and a less abundant membrane-associated species. Indirect immunoflurorescence demonstrates that Kre1p localizes to the cell surface, where it becomes concentrated at the surface of mother cells. Such a localization of Kre1p seems to parallel the CAL1/CSD2-dependent cell wall deposition of chitin found in S. cerevisiae, and is consistent with evidence from Schizophyllum commune that (1 6)--glucan accumulates during maturation of the subapical region of the wall distal to the hyphal tip.     

Circadian complexes: Circadian rhythms under common gene control

Summary Circadian rhythms for food and water consumption were measured in five inbred strains of mice under a photoperiod of 16 h light and 8 h dark (16:8 LD), and under constant light (LL).Significant strain differences were observed which indicate that a common gene difference, or set of differences inMus musculus influences both the phase angle () associating the rhythms with the light-dark cycle, and the periods (_LL) of circadian rhythms for food and water consumption. The biological clock mechanism influenced by this genetic variance is common to both food and water circadian rhythms, and differs among the five inbred strains. A positive genetic correlation was observed between the phase angle () and the period (_LL) of each rhythm. This observation can be understood in terms of a functional relationship between phase and period proposed by Pittendrigh and Daan (1976b) for the entrainment of a circadian oscillator by a light-dark cycle in nocturnal rodents.These results suggest that circadian rhythms for food and water consumption in mice are regulated by a common physiological mechanism, and would respond to natural selection as a single circadian complex under common gene control.     

βs Haplotypes in various world populations

Summary We have determined the ^s haplotypes in 709 patients with sickle cell anemia, 30 with SC disease, 91 with S--thalassemia, and in 322 Hb S heterozygotes from different countries. The methodology concerned the detection of mutations in the promoter sequences of the ^G- and ^A-globin genes through dot blot analysis of amplified DNA with ³²P-labeled probes, and an analysis of isolated Hb F by reversed phase high performance liquid chromatography to detect the presence of the ^AT chain [^A75 (E19) IleThr] that is characteristic for haplotype 17 (Cameroon). The results support previously published data obtained with conventional methodology that indicates that the ^s gene arose separately in different locations. The present methodology has the advantage of being relatively inexpensive and fast, allowing the collection of a vast body of data in a short period of time. It also offers the opportunity of identifying unusual ^s haplotypes that may be associated with a milder expression of the disease. The numerous blood samples obtained from many SS patients living in different countries made it possible to compare their hematological data. Such information is included (as average values) for 395 SS patients with haplotype 19/19, for 2 with haplotype 17/17, for 50 with haplotype 20/20, for 2 with haplotype 3/3, and for 37 with haplotype 31/31. Some information on haplotype characteristics of normal ^A chromosomes is also presented.     

The pineal complex and melatonin affect the expression of the daily rhythm of behavioral thermoregulation in the green iguana

Daily variation in the body temperature of the green iguana (Iguana iguana) was studied by telemetry in laboratory photo-thermal enclosures under a 12Light12Dark (LD) photoperiod. The lizards showed robust daily rhythms of thermoregulation maintaining their body temperatures (T_b) at higher levels during the day than during the night. Some animals maintained rhythmicity when kept in constant darkness. On lightdark cycles parietalectomy produced only a transient increase of median T_b in the first or second night following the operation. Pinealectomized lizards on the other hand maintained their body temperatures at significantly lower levels during the day and at significantly higher levels during the night than did sham-operated or intact lizards. This effect was apparently permanent, since one month after pinealectomy lizards still displayed the altered pattern. Plasma melatonin levels in intact animals were high during the night and low during the day and were unaffected by parietalectomy. Pinealectomized lizards showed low levels of plasma melatonin during both the day and the night. A daily intraperitoneal injection of melatonin in pinealectomized animals given a few minutes after the light to dark transition decreased the body temperatures selected by the lizards during the night and increased the body temperatures selected during the following day. Control injections of saline solution had no effect. The significance of these results is discussed in relation to the role of the pineal complex and melatonin in the mediation of thermoregulatory behavior.Abbreviations LD LightDark - T _b body temperature - PAR-X parietalectomy - PIN-X pinealectomy     

Die Aktivit?tsperiodik bei V?geln mit und ohne dunklem Schlafkasten

Zusammenfassung In 2 Versuchsserien wurden Kohlmeisen(Parus major) und japanische Möwchen(Lonchura striata var.domestica) einzeln und schallisoliert gehalten. In der ersten Versuchsserie, in der alle Vögel einen dunklen Schlafkasten hatten, wurde der Einfluß der Beleuchtungsstärke auf die Periode () der Hüpfaktivität und auf das Verhältnis von Aktivitätszeit zu Ruhezeit ( : -Verhältnis) untersucht. Sowhol Kohlmeisen als auch japanische Möwchen folgen der Regel, daß mit wachsender Beleuchtungsstärke die Periode kürzer und das : -Verhältnis größer wird.In der 2. Serie wurde der Einfluß Ruhe im dunklen Schlafkasten auf die Periodenlänge und auf das : -Verhältnis untersucht. Es wurden die Messungen aus Bedingung 1 (der Vogel hat einen dunklen Schlafkasten zur Verfügung) mit den Messungen aus Bedingung 2 (der Vogel hat keinen oder einen hellen Schlafkasten zur Verfügung) verglichen. Das Ergebnis bei Kohlmeisen entspricht den Befunden bei konstantem Licht verschiedener Intensität. Unter Bedingung 1 ist länger und das : -Verhältnis kleiner als in Bedingung 2. Das Ausmaß der Änderung von nach Fortnahme des dunklen Kastens ist unabhängig von der Periodenlänge in Bedingung 1. Das Ausmaß der änderung von : ist unabhängig von a : in Bedingung 1, jedoch schwach negativ korreliert mit der Periodenlänge in Bedingung 1.Bei japanischen Möwchen entsprechen die Ergebnisse dieser Versuchsserie nicht der Regel für tagaktive Vögel. Mit Benützen des dunklen Schlafkastens ist kürzer als ohne den Schlafkasten. Ohne den Schlafkasten ist etwa 24 Std. Das : -Verhältnis ist in Bedingung 1 unter bestimmten Voraussetzungen kleiner als in Bedingung 2. Das Ausmaß der Änderung von nach Fortnahme des Kastens ist mit der dazugehörigen Periode in Bedingung 1 hochsignifikant korreliert (Regressionskoeffizient b=-1.01, Korrelationskoeffizient r=0.89). Ebenfalls ist das Ausmaß der Änderung von : nach Fortnahme des Kastens mit : aus Bedingung 1 korreliert; es scheint, als würde ein bevorzugtes : -Verhältnis von etwa 2.0 eingeregelt.Die Ergebnisse werden im Hinblick auf 4 Punkte diskutiert: 1) Das circadiane System arbeitet innerhalb eines engen Bereiches von - und : -Werten optimal. 2) Der Optimalbereich wird bevorzugt unter ungünstigen Bedingungen angestrebt. 3) Der Entzug des dunklen Schlafkastens belastet japanische Möwchen mehr als Kohlmeisen. 4) Bei japanischen Möwchen wird in Bedingung 1 durch fortplfanzungsphysiologischen Einfluß verkürzt.

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Circadian activity rhythms of birds with and without a dark nest box

Summary Perch-hopping activity of Great tits(Parus major) and Bengales finches(Lonchura striata domestica), housed individually in soundproof boxes, was studied in two series of experiments. In the first series all birds had access to a dark nest box, in which they retired during their subjective night. In this experiment the effect of light intensity on the freerunning circadian activity rhythm was investigated. Both Great tits and Bengalese finches obey the circadian rule by responding to an increase in light intensity with shortening the circadian period () and with an increase of the ratio of activity time and rest time ( : ).In the second series of experiments the influence of sleeping in the dark nest box on both circadian period and : -ratio was studied. The results of two experimental conditions — without and with access to a dark nest box — were compared. In the Great tits, the results are in agreement with the effect of light intensity: when a dark nestbox is available, is longer and the : -ratio is smaller than in the absence of a nest box. The magnitude of the change in free-running period after removal of the nest box is independent of the original value of ; the amount of change : -ratio is likewise independent of the original : -ratio, but is weakly correlated to the original .InLonchura striata var. domestica, removal of the dark nest box leads to a lenghtening of the free-running period to about 24 hours; the : -ratio is smaller in the presence of a dark nestbox, if certain other conditions are fulfilled. The magnitude of the change in after removal of the nest box is highly correlated to the original free-running period (r=-0.89) in such a way that, without nest box, the period approaches a value of 24 hours. Also, the amount of change in : -ratio due to nest box removal is negatively correlated to the original : -ratio. A probably preferred : -ratio of 2.0 is adopted.These results are discussed in the view of 4 points: 1) The circadian system operates at its optimum within a narrow range of - and : -values. 2) This optimal range is especially adopted when conditions become adverse. 3) Removal of the dark nest box results in a more stressful situation for Bengalese finches than for Great tits. 4) In the Bengalese finches, is shortened in the presence of a nest box due to effects on reproductive physiology.

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Herrn Prof. Dr. JürgenAschoff zum 60. Geburtstag gewidemt.     

Nyctohemeral rhythmicity of type II thyroxine 5′-deiodinase activity in the pineal gland but not in the Harderian gland of the Swiss mouse

Type II thyroxine 5-deiodinase (5-D) activity in both pineal and Harderian glands of the Swiss mouse was studied. Pineal 5-D activity exhibited a nyctohemeral profile with a maximal peak value at 05.00 h, which coincides with that for pineal melatonin production. However, no rhythm of 5-D activity in the Harderian gland could be found. In pineal gland, light at night inhibited the nocturnal increase in 5-D activity, while isoproterenol, a -adrenergic agonist, could not stimulate the enzyme. In the Harderian gland, neither darkness, nor light at night, or isoproterenol were capable of modifying basal values of 5-D activity.     

Cytochemical studies on the localization of 5′-nucleotidase in the acinar cells of the rat salivary glands

Summary The cytochemical localization of 5-nucleotidase (5-AMPase), and its validity, were investigated in parotid and submandibular acinar cells of a rat. Biochemical determinations showed that adequate treatment with glutaraldehyde could minimize the loss of enzymatic activity, and that 5-AMPase and non-specific alkaline phosphatase (-GPase) possessed different pH optima.The cytochemical distribution of the reaction products from the 5-AMPase activity was distinct from those of -GPase. 5-AMPase activity was localized on the surface membranes of acinar, ductal and myoepithelial cells of both salivary glands. -GPase activity was evenly distributed on the entire plasma membranes of myoepithelial cells and on the basal plasmalemma of acinar cells. The reaction products, which appeared on the luminal and lateral plasma membranes of the acinar cells, were presumed to reflect the presence of 5-AMPase, while those on the myoepithelial surface and basal plasma membranes of the acinar cells demonstrated both 5-AMPase and -GPase.The results indicate that 5-AMPase activity can be utilized as a reliable marker enzyme of plasma membranes in the salivary acinar cells.     

Entrainment of the circadian system of the house sparrow: A population of oscillators in pinealectomized birds

Summary Removal of the pineal gland modifies the entrainment behavior of house sparrows. Abnormal entrainment occurs in pinealectomized sparrows exposed to skeleton photoperiods (light cycles composed of 2 pulses of light per 24-h cycle). This abnormal entrainment depends upon the state of the locomotor activity (rhythmic or arrhythmic) before exposure to the light cycle, and upon the interval between the 2 pulses of light which constitute the skeleton photoperiod. The conditions that produce abnormal entrainment in pinealectomized birds are strongly correlated with those that produce 2 stable phases of entrainment to skeleton photoperiods in normal birds (bistability phenomenon). These results suggest that after pinealectomy, there remains a population of oscillators whose combined output is reflected in the locomotor activity of individual sparrows.Abbreviations LD 12 12 light-dark cycle with 12 h of light and 12 h of dark per 24-h cycle - CT circadian time     

In vivo effects of insulin and bis(maltolato)oxovanadium (IV) on PKB activity in the skeletal muscle and liver of diabetic rats

In this study, the in vivo effects of insulin and chronic treatment with bis(maltolato)oxovanadium (IV) (BMOV) on protein kinase B (PKB) activity were examined in the liver and skeletal muscle from two animal models of diabetes, the STZdiabetic Wistar rat and the fatty Zucker rat. Animals were treated with BMOV in the drinking water (0.75–1 mg/ml) for 3 (or 8) weeks and sacrificed with or without insulin injection. Insulin (5 U/kg, i.v.) increased PKB activity more than 10fold and PKB activity more than 3fold in both animal models. Despite the development of insulin resistance, insulininduced activation of PKB was not impaired in the STZdiabetic rats up to 9 weeks of diabetes, excluding a role for PKB in the development of insulin resistance in type 1 diabetes. Insulin-induced PKB activity was markedly reduced in the skeletal muscle of fatty Zucker rats as compared to lean littermates (fatty: 7fold vs. lean: 14fold). In contrast, a significant increase in insulinstimulated PKBa activity was observed in the liver of fatty Zucker rats (fatty: 15.7fold vs. lean: 7.6fold). Chronic treatment with BMOV normalized plasma glucose levels in STZdiabetic rats and decreased plasma insulin levels in fatty Zucker rats but did not have any effect on basal or insulininduced PKB and PKB activities. In conclusion (i) in STZdiabetic rats PKB activity was normal up to 9 weeks of diabetes; (ii) in fatty Zucker rats insulininduced activation of PKB (but not PKB) was markedly altered in both tissues; (iii) changes in PKB activity were tissue specific; (iv) the glucoregulatory effects of BMOV were independent of PKB activity.