Light responses and diurnal rhythms in desert Tenebrionidae

By means of choice-chamber experiments, Ocnera hispida and, to a lesser extent, Pimelia grandis were shown to exhibit photonegative responses at all temperatures while Adesmia antiqua was photopositive. The intensity of the light reactions of the first two species was not influenced by the temperature, but A. antiqua was more markedly photopositive at higher temperatures. All species respond to near-lethal temperatures by digging into the sand. Analysis of aktograph records showed that O. hispida and P. grandis are strictly nocturnal, A. antiqua diurnal in habit. The endogenous chromometer in P. grandis is retarded by cold, but is not re-set.

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Résumé Des expériences effectuées au moyen d'une choice-chamber ont démontré que O. hispida et à un degré inférieur P. grandis ont des réponses photonégatives à toutes les températures, tandis que A. antiqua est photonégative.L'intensité des réactions à la lumière des deux premières espèces n'a pas été influencée par la température, mais A. antiqua était nettement plus photopositive à des températures plus élevées. Aux températures sublétales toutes les espèces répondent par un enfouissement dans le sable.L'analyse des données aktographiques a démontré que O. hispida et P. grandis sont rigoureusement nocturnes, tandis que A. antiqua est une espèce diurne. Le chronomètre endogène chez P. grandis est retardé par le froid, mais le retard n'est pas rattrapé.

     

Interindividual influence on diurnal rhythms of activity in cycling and noncycling populations of the field vole,Microtus agrestis L.

Summary The effects of interaction among individuals with respect to wheelrunning activity has been investigated in two geographically separated populations of the field vole Microtus agrestis L. In one of them, a northern cyclically varying population, a strictly nocturnal activity pattern is changed into a more or less short term 24 h pattern under conditions of increased contact among individuals. In the other population, south-Swedish, without population cycles, no such effects were observed. This indicates population differences in response to interindividual contact which might be of importance to the known differences in population dynamics.     

Photoperiodic control of circadian activity rhythms in diurnal rodents

The responses of red squirrels(Tamiasciurus hudsonicus) and eastern chipmunks(Tamias striatus) to complete and skeleton light-dark (LD) cycles were compared. The skeletons, comprised of two 1-h pulses of light per day, effectively simulated the complete photoperiods in the squirrels, but not the chipmunks. Skeleton photoperiods greater than 12-h caused the chipmunks to shift activity from the longer to the shorter of the two intervals between the pulses. To interpret the mechanism of phase control, squirrels and chipmunks were kept in continuous darkness and exposed to 1-h light pulses every 10 days. The time-course of entrainment was also quantified. Both techniques produced light-response curves. The data suggest that the parametric and non-parametric contributions to entrainment are different in these two rodent species.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Parasite-induced alteration of diurnal rhythms in a freshwater snail

The trematode Microphallus sp. alters the behavior of its snail intermediate host, Potamopyrgus antipodarum, in ways that seem to increase transmission to its final host, e.g., waterfowl, and decrease the probability of being eaten by other predators, e.g., fish. The parasite seems to cause the snail to move from the top to the bottom of rocks at about 0900 hr. Waterfowl feed predominantly before 0900 hr, and fish feed predominantly after 0900 hr. In the present study, we tested the hypothesis that Microphallus sp.-infected snails exhibit a change in behavior at around 0900 hr by examining their response to light and vertical orientation before and after 0900 hr. Results demonstrated that uninfected snails generally move toward light, oriented downward, and move a greater distance in the light compared with the dark at all times of day. Microphallus sp.-infected snails behaved differently from uninfected snails in the early morning but similarly to uninfected snails in the late morning with regard to downward orientation and distance moved in response to light. Snails infected with parasites other than Microphallus sp. behaved similarly to uninfected snails during both time periods. These results suggest that Microphallus sp. manipulates the behavior of Potamopyrgus sp. by altering rates of movement in response to light and vertical orientation in a manner consistent with the hypothesized 0900-hr shift.     

The influence of intravenous infusion of electrolytes on the diurnal excretory rhythms

In freely moving rats the diurnal variation in electrolyte excretion was studied. Food was available during either the dark or the light period. The lights were on from 0800–2000; the dark phase extended from 2000–0800 hrs. The electrolyte excretory rhythms were studied during a control period, in which the minerals were present in the food, and during experimental periods, when successive minerals were not present in the food but were instead given by constant intravenous infusion. For both groups the excretory rhythms of K, Mg and P persisted during continuous infusion but the times of maximum and minimum excretion differed. Day-fed animals exhibited a remarkable decrease in amplitude during the mineral infusion period. In contrast, the calcium excretory pattern was only influenced by the feeding period.     

Effect of light intensity on broiler behaviour and diurnal rhythms

Light intensity manipulation is an important management tool affecting broiler behaviour and physiology but still there is a debate regarding the optimum level to be used in confinement barns. Two experiments were completed to study the impact of light intensity (1, 10, 20 and 40 lx) on behaviour and diurnal rhythms of broilers raised to 35 d of age. For each experiment, 950 Ross × Ross 308 chicks were housed per room with replication of individual light intensity treatment in two environmentally controlled rooms. Within each large room, a small pen with 25 male and 25 female chicks was used for recording behaviour. Data were analyzed as a randomized complete block design with experiment acting as a block. All chicks were provided with 40 lx intensity and 23 h light until shifting to treatment light intensity and 17 h daylength at 7 d of age. For each replicate, behaviour was recorded for a 24 h period, starting at 16 or 17 d of age. At 23 d of age, three birds per room were bled at the start, middle and end of light and dark periods for melatonin estimation using RIA. When summarized over the 24 and 17 h observation periods, birds exposed to a light intensity of 1 lx rested more (P = 0.01) and preened (P < 0.05) and foraged (P < 0.05) less in comparison to other light intensities. Birds from all treatments exhibited diurnal rhythms for feeding, resting, drinking, walking, standing, foraging and preening behaviours with little or no activity during the 7 h dark phase. The serum melatonin levels at the start, middle and end of light and dark phases were unaffected by light intensity (P > 0.1). In conclusion, light intensity ranges from 1 to 40 lx did not affect melatonin levels or behavioural diurnal rhythms, but birds exposed to a light intensity of 1 lx rested more and preened less, potentially indicating a reduced welfare state.     

Thermoregulation and diurnal rhythms in 1-week-old rat pups

This paper reviews the ontogeny of thermoregulation and diurnal rhythmicity in rats. Additionally, original data are presented that indicate the emergence of an endogenous circadian core temperature rhythm during the first postnatal week. Despite neurological immaturity, newborn rats display autonomic and behavioral thermoregulatory responses within 24 h of birth. Their "biological clock" is already running before birth. The thermal environment of pups changes cyclically owing to diurnal variations in maternal behavior, but the core temperatures of 1-week-old pups huddling in the absence of the dam also show marked diurnal fluctuations. Five- to 8-day-old lean Zucker rat pups artificially reared in the absence of 24-h cycles of ambient temperature and food intake show diurnal changes in core temperature similar to those in huddling mother-reared pups. Diurnal core temperature changes, evident only when regulatory effectors are not overwhelmed, are one of the first self-maintained diurnal rhythms to appear. Because thermoregulation and circadian rhythmicity both appear before maturation of the neural networks believed to be critical for their control in adult animals, studying the immature rat might increase our understanding of the control of these processes in the more complex mature central nervous system.     

A compartmental model for the study of diurnal rhythms in cell proliferation

A mathematical model taking into account the observed diurnal variations in cell kinetics is presented. Its principle is to divide each phase of the cell cycle into a definite number of compartments and to assume time-dependent probabilities of transition from one compartment to the following; general properties of the model are derived.The particular case where the only time-dependent transition probabilities are those corresponding to the G₁ phase is studied. A characterization of the joint percentages of S and M cells variations is given. The application of the model to interpretation of published experimental data obtained in hamster cheek pouch epithelium is given.     

Studies in diurnal rhythms ix the water-relations of some nocturnal tropical arthropods

The rate of water-loss from tropical African centipedes (Rbysida nuda and Ethmostigmus trigonopodus) and millipedes (Oxydesmus platycercus and Ophistreptus sp.) is proportional to the saturation deficiency of the atmosphere. These animals therefore resemble forms from temperate and desert regions in this aspect of their physiology. Their nocturnal habits are probably related to their high rate of transpiration. The endogenous 24-hour rhythm shows a slight retardation in constant light and an acceleration in darkness. The probable function of this is to synchronize it with diurnal environmental changes. The West African scorpion, Pandinus imperator, has a critical temperature considerably lower than those of desert species and comparable with that of the Italian Euscorpius germanus.

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Zusammenfassung Bie den tropischen afrikanischen Hundertfüßlern Rhysida nuda und Ethmostigmus trigonopodus, den Tausendfüßlern Oxydesmus platycercus und Ophistreptus sp. sowie bei dem Skorpion Pandinus imperator wurden die Wasserverlustraten durch Wägen der Individuen bestimmt, die über Phosphorpentoxyd in konischen Flaschen aufgehängt wurden, die in ein Wasserbad tauchten. Die Tiere wurden jeder Temperatur 20 Minuten lang ausgesetzt, bevor der durch Evaporation bedingte Betrag des Wasserverlustes bestimmt wurde. Es wird gezeigt, daß diese Methode wertvolle Vergleiche zwischen den verschiedenen Arten zu ziehen gestattet. Sowohl bei Hundertfüßlern wie auch bei Tausendfüßlern erwies sich die Transpiration als proportional zum Sättigungsdefizit der Luft. Diese Tiere ähneln deshalb in diesem Punkte ihrer Physiologie Arten aus gemäßigten und Wüsten-Gebieten.Ihre nächtliche Lebensweise, die mittels Aktographen festgestellt wurde, steht wahrscheinlich in Beziehung zu der vergleichsweise hohen Wasserverlustrate. Der endogene diurnale Rhythmus ziegt eine leichte Verzögerung bei Dauerbelechtung und eine Beschleunigung bei Dunkelheit. Auf diese Weise wird wahrscheinlich die Periodizität dieser Tiere mit dem 24-Stunden-Rhythmus der Umgebung synchronisiert.Die kritsche Temperatur des westafrikanischen Skorpions Pandinus imperator liegt beträchtlich niedriger als die der Wüsten-Arten und ähnelt der des italienischen Euscorpius germanus. Es wird vermutet, daß in diesem Falle die nächtliche Lebensweise in Beziehung steht zu der Gefährdung des großen, langsamen Tieres durch räuberische Wirbeltiere.Es wird geschlossen, daß im allgemeinen die Transpirationsrate in Beziehung zum Habitat steht und bei Wüstenbewohnern am niedrigsten ist.

     

Probing the effects of light and temperature on diurnal rhythms of phytosiderophore release in wheat

* The existing literature is ambiguous as to whether the diurnal pulse in phytosiderophore (PS) release in the Poaceae is mediated by light or temperature, or both. * Here, wheat (Triticum aestivum cv. Yecora Rojo) seedlings were grown in Fe-sufficient (pFe = 16.5) and Fe-deficient (pFe = 17.8) chelator-buffered nutrient solutions. Six different light/temperature regimes were tested over 8 d in paired growth chambers. * Phytosiderophore release patterns under a square-wave light regime were similar, irrespective of whether temperature was varied diurnally or held constant, but PS release was negligible when the light was removed. Release patterns of PS for Fe-deficient and Fe-sufficient plants grown under the square-wave vs ramped light and temperature regimes were similar in the corresponding Fe treatments. * Our results strongly support the notion that the diurnal pulse in PS release in the Poaceae is mainly mediated by changes in light rather than temperature. Our comparison of square-wave with more natural ramped light/temperature regimes suggests that the diurnal response patterns of PS release in wheat can be confidently studied using traditional square-wave regimes, and this is likely to be the case with other Poaceae as well.     

Microclimate,diurnal rhythms and the conquest of the land by arthropods

Summary A review is given of the adaptations of arthropods to life on land. The terrestrial Arthropoda are divided ecologically into two main groups. The first of these includes woodlice, centipedes, miilipedes and their allies which lose water rapidly in dry air and consequently are restricted to damp, dark habitats which they leave only at night when the temperature falls and the relative humidity of the air rises. The second group includes most insects and Arachnida: these are comparatively independent of moist surroundings because their integument possesses an impervious layer of wax which prevents desiccation.     

黑腹果蝇昼夜活动节律及行为时间分配

采用试验室单管观察记录的方法,对3,4,5日龄野生型黑腹果蝇Drosophila melanogaster Meigenw1118成虫每日活动节律进行研究。试验将果蝇活动划分为强活动(飞行和爬行)、弱活动(梳理、觅食等原地发生的运动)和静息(身体不发生移动的休息)3种类型。强活动和弱活动之和为总运动。研究结果显示,野生型黑腹果蝇w1118的昼夜活动表现为明显的双峰模态,晨峰和晚峰分别处于开、关灯前后;雌、雄果蝇总体活动无差异,关灯(18:30)前后雌蝇活动稍强于雄蝇,开灯(6:30)前后则相反;果蝇强活动的节律与总运动基本一致,而弱活动节律不明显;静息节律为单峰模式,其高峰期位于夜间1:00~5:00;雌蝇的静息活动显著多于雄蝇(P<0·05)。