Temporal pattern of locomotor activity in Drosophila melanogaster

The temporal pattern of locomotor activity of single Drosophila melanogaster flies freely walking in small tubes is described. Locomotor activity monitored by a light gate has a characteristic time-course that depends upon age and the environmental conditions. Several methods are applied to assess the complexity of the temporal pattern. The pattern varies according to sex, genotype, age and environmental conditions (food; light). Activity occurs clustered in bouts. The intrinsic bout structure is quantified by four parameters: number of light gate passages (counts) per bout, duration of a bout, pause between two successive bouts and mean bout period. In addition, the distribution of the periods between light-gate crossings (inter-count intervals) as function of inter-count interval duration reveals a power law, suggesting that the overall distribution of episodes of activity and inactivity has a fractal structure. In the dark without food, the fractal dimension which represents a measure of the complexity of the pattern is sex, genotype and age specific. Fractality is abolished by additional sensory stimulation (food; light). We propose that time-course, bout structure and fractal dimension of the temporal pattern of locomotor activity describe different aspects of the fly's central pattern generator for locomotion and its motivational control. Accepted: 10 October 1998     

Temporal pattern of eating in night shift workers

ABSTRACT

Understanding shift workers dietary intake patterns may inform interventions targeted at lowering chronic disease risk. This study examined the temporal distribution of food intake as shift workers rotate between night shifts, day shift and/or days off to identify differences in energy intake, eating frequency, and adherence to dietary guidelines by shift type (night shift vs. day). Night shift (NS) workers completed a four-day food diary that included a minimum of two night shifts and one-day shift (DS)/day off (DO), recording all food, beverages and time of consumption. Comparisons were between shift types, using ANOVA for continuous data and generalized estimating equations for count data, data reported as mean (SE). When comparing NS and DSDO, there were no differences in energy intake (24 h) (8853 (702) vs. 9041 (605) kJ, n = 22) or adherence to dietary guidelines. There was no difference between the number of eating occasions on NS and DSDO (5.6(0.3) vs 5.1(0.6) occasions) but less energy per eating occasion at night (1661(125) vs 1933(159) kJ). When working NS compared with DSDO there was higher total sugar (%E, 19.1(2.0) vs 15.0(2.4)) and lower saturated fat (%E, 13.8(1.2) vs 15.7(1.3)). Further, DSDO were characterized by a pattern of three main meals and a prolonged fasting period. It is important to determine if reducing eating occasions and providing opportunities for fasting improves metabolic health.     

Green vegetable drink consumption protects peripheral lymphocytes DNA damage in Korean smokers

Smoking increases indices of free radical-mediated damage of DNA which are potential underlying processes in the pathogenesis of many diseases. In this study, we evaluated whether 8 weeks of green vegetable drink (Angelica keiskei based juice) supplementation to smokers can be protective against lymphocytic DNA damage. Twenty smokers were given 240 ml of commercially available green vegetable drink every day for 8 weeks. The DNA damage was determined using single cell gel electrophoresis (COMET assay) and the damage was quantified by measuring tail length (TL), tail moment (TM), and percent DNA in tail. Eight weeks of green vegetable drink consumption resulted in a significant in lymphocytes DNA damage in all three measurements; TL, TM and % DNA in tail. These results support the hypothesis that green vegetable drink exerts a cancer-protective effect via a decrease in oxidative damage to DNA in humans.     

Temporal pattern discrimination of impulse sequences in the computer-simulated nerve cells

This paper deals with some properties of temporal pattern discrimination performed by single digital-computer simulated synaptic cells. To clarify these properties, the Shannon's entropy method which is a basic notion in the information theory and a fundamental approach for the design of pattern classification system was applied to input-output relations of the digital computer simulated synaptic cells. We used the average mutual information per symbol as a measure for the temporal pattern sensitivity of the nerve cells, and the average response entropy per symbol as a measure for the frequency transfer characteristics. To use these measures, the probability of a post-synaptic spike as a function of the recent history of pre-synaptic intervals was examined in detail. As the results of such application, it was found that the EPSP size is closely related to the pattern of impulse sequences of the input, and the average mutual information per symbol for EPSP size is given by a bimodal curve with two maximum values. One is a small EPSP size and the other is a large EPSP size. In two maximum points, the structure of the temporal pattern discrimination reverses each other. In addition, the relation between the mean frequency, or the form of impulse sequences of the input, and the average mutual information per symbol has been examined. The EPSP size at one maximum point of average mutual information is in inverse proportion to the magnitude of input mean frequency which relates to the convergence number of input terminal, while that at the other maximum point is proportional to that of the mean frequency. Moreover, the temporal pattern discrimination is affected remarkably by whether successive interspike intervals of the input are independent or not in the statistical sense. Computer experiments were performed by the semi-Markov processes with three typical types of transition matrixes and these shuffling processes. The average mutual informations in the cases of these semi-Markov processes are in contrast to those of the shuffling processes which provide a control case. The temporal structure of successive interspike intervals of the input is thus a significant factor in pattern discrimination at synaptic level.     

Temporal mortality pattern of pedunculate oaks in southern Sweden

Decline of the oak forests decline in southern Sweden has been reported for more than two decades. Little empirical data exists, however, to study the temporal pattern of the phenomenon in detail. In this study we quantified the temporal pattern of non-windfall oak mortality by analyzing the dataset of 44 dendrochronologically dated dead pedunculate oak (Quercus robur L.) trees. We compared tree-ring chronologies from recently dead and living trees from the same sites (number of sites=13) located in the nemoral and boreo-nemoral zones in southern Sweden. For each dead tree, tree-ring chronologies were analyzed for the presence of pre-death growth depressions. A growth depression was defined as a period (of one or more years) when growth remained below the 5%, 7%, or 10% quantiles of the ring-width distribution obtained from living trees for a particular year and site.

The most recent peak in oak mortality occurred around the year 2000. Growth depressions were recorded in 80% (n=35) of all dead oaks and were most prominent during the 1990s. While some oaks showed an obvious reduction in growth over several decades, 51% of the dead trees had growth depression for at least 4 years prior to death. Although diameter growth rate differed between living and recently dead trees for at least 30 years, this difference started to amplify in late 1980s–early 1990s. Presence of pre-death growth depression in tree-ring chronologies implies that (a) non-windfall mortality of oak is a decade-long process and (b) the actual death events might be lagging behind the timing of the mortality-inducing factors. ANOVA revealed significant differences in tree responses to the drought year 1992. The cumulative growth increment ratio between 1992–1994 and 1989–1991, was higher in living trees than in those that had recently died. We suggest that the spring and summer drought of 1992 resulted in the mortality of oaks that was observed in southern Sweden at the end of the 20th century. If this time lag exists, it may complicate analyses of decline-related factors and the choice of appropriate actions by forest managers. We conclude that studies of oak decline may benefit from widening the time perspective to include several decades preceding the sampling year.     

Temporal pattern of wild ungulate-related traffic accidents in northwest Spain

Wildlife-related accidents are a serious problem in different countries and describing their temporal pattern allows for the development of measures to mitigate them. We described the temporal pattern of wild ungulate-related accidents occurring between January 2006 and December 2010 in the Autonomous Region of Galicia, northwest of Spain. We examined the temporal distribution of the accidents according to months, phenological and hunting seasons, days of the week and time of the day. From the 6,255 wild ungulate-related traffic accidents analysed, 36.5% were related to roe deer Capreolus capreolus and 62.8% were related to wild boar Sus scrofa. The monthly distribution of accidents was not random but follows a characteristic pattern for each species. Roe deer-related accidents have their maximum in April and May, coinciding with the breeding season, followed by July, coinciding with the rut. Wild boar-related accidents have their maximum between October and January, coinciding with the hunting season but also with months with the longest nights. Both roe deer- and wild boar-related accidents showed an increase at weekends, specially on Sundays. During the hunting season, the wild boar-related accidents showed a marked peak on the same day. This weekly pattern was explained by drivers’ behaviour and by hunting. For roe deer, peaks of accidents occurred between 19:00 and 22:00 (about dusk) and between 05:00 and 08:00 (about dawn). For wild boar, 69% of accidents occurred between 18:00 and 23:00, coinciding with dusk and night. This daily pattern of accidents was explained by the behaviour of the species.     

Oestradiol inhibits the insulin secretion on the first day of treatment in the ovariectomized rat

Long term oestradiol treatments stimulate the B cell of the endocrine pancreas. The first effects of oestradiol-17-beta were studied in ovariectomized rats, 16 hours after a subcutaneous injection of various concentrations of this hormone (0, 2.5, 25, 50 micrograms). Plasma oestradiol concentrations, food intake and insulin secretion from islets of Langerhans were measured. Oestradiol always decreased food intake and insulin secretion. However, this inhibiting effect of oestradiol on the B cell was also found in fasted rats. This negative action did not appear on basal insulin secretion but on glucose-induced insulin response. It was characterized by a decrease in the B cell capacity of response to glucose. Short and long term opposite actions of oestradiol on the B cell of the endocrine pancreas could be compared to similar effects shown with glucocorticoids.     

Temporal pattern sensitive and nonsensitive responses in the cat's retinal ganglion cells

In order to characterize temporal pattern sensitivity in the cat ganglion cells, a new analysis technique by semi-Markov models which was developed in the previous papers (Tsukada et al., 1975–1977) was applied to input-output relations of the receptive-field. Three types of statistical spot stimuli positioned in the center region of receptive fields were used. Each type of stimulus has an identical histogram in the inter-stimulus intervals and therefore the same mean and variance, but different correlations between adjacent inter-stimulus intervals (Type 1, positive; Type 2, negative; and Type 3, independent processes). From the output spike trains of cat retinal ganglion cells to each stimulus, mean, variance, and histogram were computed. As the result of investigating these data, we could draw the following conclusion from the resultant output interval histograms. The receptive-field-center responses of cat ganglion cells can be classified into two groups (Types L and N) according to the difference of responsiveness to the three types of statistical spot stimuli. A Type L response has the same histogram in interspike intervals for all three stimuli, and is not sensitive to the temporal pattern, while a Type N response has three different forms depending on each type of stimulus showing high sensitivity to the temporal pattern. These results were also simulated by the Markov chain model and discussed with relation to neural coding and classification of ganglion cell types.     

苜蓿人工草地节肢动物群落的时间格局

调查了甘肃省庄浪县苜蓿人工草地节肢动物群落的组成及多样性变化,应用主分量分析和最优分割法对节肢动物群落的时间格局进行了研究。结果表明,苜蓿人工草地节肢动物群落的物种丰富度,多样性和均匀度指标在时间过程中的变化有明显的差异和规律性,6月下旬害虫和天敌的物种丰富度均达到最大值,但天敌的个体数量高峰明显落后于害虫,在时间变化过程中,影响节肢动物群落的主导因素和时间格局分化明显,根据研究结果,将苜蓿人工草地节肢动物群落在时间动态中的变化划分为5月上旬以前,5月中旬-6月上旬,6月中旬-7月中旬,7月中旬以后4个阶段,并结合气候,物候变化,分析了各阶段内主要害虫和天敌的发生特点,提出了害虫的治理对策。     

The cell cycle in the shoot apex ofSilene during the first day of floral induction

Summary The length of the cell cycle was measured in the shoot apical meristem ofSilene coeli-rosa during the first day of an inductive photoperiod. The length of the cell cycle in the shoot apex of vegetative controls (those in short days) was about 18–20 hours. Exposure of plants to the long day resulted in an immediate shortening of the cell cycle to about 13 hours, roughly two thirds of that in short days. Measurements of the component phases of the cell cycle revealed that the shortened cycle in long days was the result of a decrease in the length of G 1 and perhaps S, whilst G 2 and M remained constant.     

Temporal pattern sensitivity of long-term potentiation in hippocampal CA1 neurons

High-frequency electrical stimulation in the hippocampus leads to an increase in synaptic efficacy that lasts for many hours. This long-term potentiation (LTP) of synaptic transmission is presumed to play a crucial role in learning and memory in the brain. However, the frequency of stimulation generally used to obtain LTP is beyond the normal physiological range of activity of hippocampal neurons. We found that LTP can be induced by an electrical stimulation whose frequency is comparable to that of the naturally occurring firing activity of hippocampal neurons if the stimulating pulseinterval train has a special time structure. In the present experiment, we compared the magnitude of LTP induced by the four types of stimuli which have the same pulse number and the same mean frequency but different time structure in interstimulus intervals. One type of stimuli has regular intervals, and this served as a control stimulus. In the other three types of stimuli, the adjacent interstimulus interval had the following statistical properties: in type 1, their correlations are positive; in type 2, negative; and in type 3, independent. The magnitude of LTP induced by these four types of stimuli showed clear order relationships: type 3/type 1 control > type 2. Detailed analysis of the evoked potential during a period of temporal pattern stimulation revealed that the amplitude of the population spikes of repetitive firing, especially of the second and third population spikes, had the same order relationship as the LTP. Because 2-amino-5-phosphonovalerate (APV) (50 M) selectively abolished the second and the third population spikes but not the first, and blocked the formation of LTP, the second and the third peaks which appeared as part of the late component of excitatory postsynaptic potentials (EPSP) must involve LTP formation through the activities of N-methy-D-aspartate (NMDA) channels. From the experimental data, a dynamic induction rule concerning LTP in specific neural networks was derived by which the temporal information of the input stimuli can be extracted and transformed into the weight space of synaptic connections in hippocampal networks (see Fig. 1. CA1).