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Introduction
Publications
Publications (75)
Rapid, ultradian biological rhythms are only partly comparable to circadian (24-h) rhythms. Often, the ensuing expectations from this comparison are that 1) ultradian rhythms should be driven by discrete oscillators, 2) they are biochemically buffered, and 3) they must be functionally linked to extrinsic events and cycles. These three expectations...
Career development of Science students seems dependent on more than disciplinary education, such as the nature and focus of career preparation. In this study we compare graduate outcomes of science students at the University of Groningen, completing two master-level program streams with different focal points, by using career progress surveys from...
Metabolic rhythms include rapid, ultradian (hourly) dynamics, but it remains unclear what their relationship to circadian metabolic rhythms is, and what role meal timing plays in coordinating these ultradian rhythms in metabolism. Here, we characterized widespread ultradian rhythms under ad libitum feeding conditions in the plasma metabolome of the...
The need for employees in the exact and natural sciences sector with both work experience and academic qualifications, especially combined with an entrepreneurial mindset, is rising. The University of Groningen offers an alternative Master’s program entitled Science, Business and Policy (SBP). SBP combines entrepreneurship education with the integr...
The Science, Business and Policy Program (SBP) of the University of Groningen has been a work-based learning program for science master students since two decades. This program, a direct consequence of the Bologna declaration of education in Europe, has a distinctive position in European science curricula. Here, we use a web-based survey (N = 242),...
Rodent studies have been critical to exposing and defining fundamental properties of biological rhythms and underlying timing systems. Studying biological timekeeping in animals is a valid curiosity in itself, and studies in rodents are also often used to model the human condition where human studies cannot be undertaken due to practical or ethical...
Although there may be large differences between scientific and traditional knowledge traditions, the possible role of traditional knowledge for natural management and ecological restoration is increasingly recognized and implies the engagement of local people in conservation and restoration projects. This paper explores several forms of community e...
Globally, traditional knowledge is at stake, notwithstanding intentions recorded in international policy conventions. Egypt has accepted and ratified several conventions on implementation of traditional knowledge in the fields of environment and sustainable development; yet this implementation is hampered by a lack of concrete plans. Focusing on th...
A strong theoretical approach with a specific focus on disciplinary research characterizes the common science master’s education in the Netherlands. However, a work-based learning (WBL) approach may as well be expedient and suitable for science education at master’s level. In this paper, a case study is presented of a WBL-program designed for an ac...
This paper identifies practices that can facilitate knowledge transfer in university–industry (U–I) research partnerships by systematically reviewing extant literature. We aim to contribute to the theoretical development in the field of academic engagement and propose that knowledge transfer provides a valuable perspective. We started our review wi...
In this study, we investigate the impact of the formation of Lake Nasser in the mid-1960s and the establishment of a new village in the vicinity of the lake in the early 2000s on traditional knowledge of a Bedouin community. We focus particularly on items relating to rangeland and settlement. Questions, based in part on literature, were asked in in...
In humans and most other species, changes in the intensity and duration of light provide a critical set of signals for the synchronisation of the circadian system to the astronomical day. The timing of activity within the 24 h day defines an individual’s chronotype, i.e. morning, intermediate or evening type. The aim of this study was to investigat...
Most processes within organisms, and most interactions between organisms and their environment, have distinct time profiles. The temporal coordination of such processes is crucial across levels of biological organization, but disciplines differ widely in their approaches to study timing. Such differences are accentuated between ecologists, who are...
Biological oscillations with an ultradian time scale of 1 to several hours include cycles in behavioral arousal, episodic glucocorticoid release, and gene expression. Ultradian rhythms are thought to have an extrinsic origin because of a perceived absence of ultradian rhythmicity in vitro and a lack of known molecular ultradian oscillators. We desi...
The distribution and abundance of plant species are strongly linked to the physical environmental and thus to anthropogenic disturbances. Changes in desert vegetation, in particular, can have drastic impacts on human livelihoods in these areas as ecosystem services may be affected (Dubroeucq and Livenais 2004; Klintenberg et al.2007; Kayhko et al.2...
Introduction: with time-place learning (TPL), animals link an event with the spatial location and the time of day. The
what-where-when TPL components make the task putatively episodic-like in nature. Animals use an internal sense of time to master TPL, which is circadian system based. Finding indications for a role of the hippocampus and (early) ag...
Time-place learning (TPL) offers the possibility to study the functional interaction between cognition and the circadian system with aging. With TPL, animals link biological significant events with the location and the time of day. This what-where-when type of memory provides animals with an experience-based daily schedule. Mice were tested for TPL...
Abstract
This paper explores the practices used to facilitate knowledge transfer in collaborative research project between academics and industry. What are the barriers to knowledge transfer in University-Industry (U-I) research collaboration and what are practices to overcome these barriers, as represented in literature? The most important barrier...
This paper explores the practices used to facilitate knowledge transfer in collaborative research project between academics and industry. What are the barriers to knowledge transfer in University-Industry (U-I) research collaboration and what are practices to overcome these barriers, as represented in literature? The most important barriers to know...
During Time-Place Learning (TPL), animals link biological significant events (e.g. encountering predators, food, mates) with the location and time of occurrence in the environment. This allows animals to anticipate which locations to visit or avoid based on previous experience and knowledge of the current time of day. The TPL task applied in this s...
With time-place learning, animals link a stimulus with the location and the time of day. This ability may optimize resource localization and predator avoidance in daily changing environments. Time-place learning is a suitable task to study the interaction of the circadian system and memory. Previously, we showed that time-place learning in mice dep...
Circadian rhythms are ubiquitous in many organisms. Animals that are forced to be active around the clock typically show reduced performance, health and survival. Nevertheless, we review evidence of animals showing prolonged intervals of activity with attenuated or nil overt circadian rhythms and no apparent ill effects. We show that around-the-clo...
In 1942, Walls described the concept of a 'nocturnal bottleneck' in placental mammals, where these species could survive only by avoiding daytime activity during times in which dinosaurs were the dominant taxon. Walls based this concept of a longer episode of nocturnality in early eutherian mammals by comparing the visual systems of reptiles, birds...
Time-Place learning (TPL) refers to the ability of animals to remember important events that vary in both time and place. This ability is thought to be functional to optimize resource localization and predator avoidance in a circadian changing environment. Various studies have indicated that animals use their circadian system for TPL. However, not...
The annual cycle of changing day length (photoperiod) is widely used by animals to synchronise their biology to environmental seasonality. In mammals, melatonin is the key hormonal relay for the photoperiodic message, governing thyroid-stimulating hormone (TSH) production in the pars tuberalis (PT) of the pituitary stalk. TSH acts on neighbouring h...
Blue mussel (Mytilus edulis) beds increase the diversity in habitats and the biodiversity of the Wadden Sea. They are, e.g., an important source of food for birds. However, in the early 90s due to storms, bad spat fall, and fishery, a large amount of mussel beds were removed. This was the trigger of a strong conflict between mussel fishers and envi...
Light is the main entraining signal of the central circadian clock, which drives circadian organization of activity. When food is made available during only certain parts of the day, it can entrain the clock in the liver without changing the phase of the central circadian clock. Although a hallmark of food entrainment is a behavioral anticipation o...
The heat dissipation limit theory suggests that heat generated during metabolism limits energy intake and, thus, reproductive output. Experiments in laboratory strains of mice and rats, and also domestic livestock generally support this theory. Selection for many generations in the laboratory and in livestock has increased litter size or productivi...
Voluntary physical activity may be related to personality traits. Here, we investigated these relations in two mouse lines
selectively bred for high voluntary wheel-running behavior and in one non-selected control line. Selection lines were more
explorative and “information gathering” in the open-field test, either with increased upright positions...
The suprachiasmatic nuclei of the hypothalamus (SCN) are the master circadian clock in mammals. Transcriptional activity in this master clock has a marker in the immediate-early gene c-Fos. Within the SCN, distinct differences in c-Fos in the ventrolateral and the dorsomedial SCN have been reported for rodent species such as rats, mice, and hamster...
Endogenous biological clocks allow organisms to anticipate daily environmental cycles. The ability to achieve time-place associations is key to the survival and reproductive success of animals. The ability to link the location of a stimulus (usually food) with time of day has been coined time-place learning, but its circadian nature was only shown...
Circadian organisation of behavioural and physiological rhythms in mammals is largely driven by the clock in the suprachiasmatic nuclei (SCN) of the hypothalamus. In this clock, a molecular transcriptional repression and activation mechanism generates near 24 hour rhythms. One of the outputs of the molecular clock in specific SCN neurons is arginin...
In common voles (Microtus arvalis), natural variation in locomotor behavior can be exploited to study the mechanism of pacemaker control over circadian timing of behavior. Here we studied daily patterns in numbers of neuropeptide immunoreactive suprachiasmatic nucleus neurons in rhythmic, weakly rhythmic, and non-rhythmic voles. Circadian rhythmic...
Biological rhythms are a result of interplay between endogenous clocks and the ambient light-dark (LD) cycle. Biological timing in resident polar organisms presents a conundrum because these experience distinct daily LD cycles for only a few weeks each year. We measured locomotor activity in reindeer, Rangifer tarandus platyrhynchus (SR, n = 5 and...
In most mammals, daily rhythms in physiology are driven by a circadian timing system composed of a master pacemaker in the suprachiasmatic nucleus (SCN) and peripheral oscillators in most body cells. The SCN clock, which is phase-entrained by light–dark cycles, is thought to synchronize subsidiary oscillators in peripheral tissues, mainly by drivin...
The light/dark cycle of day and night synchronizes an internal 'biological clock' that governs daily rhythms in behaviour, but this form of regulation is denied to polar animals for most of the year. Here we demonstrate that the continuous lighting conditions of summer and of winter at high latitudes cause a loss in daily rhythmic activity in reind...
Arg8-vasopressin (AVP), a circadian clock-controlled gene product, is released from the hypothalamic suprachiasmatic nuclei (SCN) in mice in a circadian fashion. Previously reported differences in two mouse lines, initially selected for thermoregulatory nest-building behavior (building small nests (S-mice) or big nests (B-mice)) with different circ...
The suprachiasmatic nucleus (SCN) is engaged in modulation of memory retention after (fear) conditioning, but it is unknown which pathways and neurotransmitter system(s) play a role in this action. Here we examine immunocytochemically whether muscarinic acetylcholine receptors (mAChRs), mediating cholinergic signal transduction in the SCN, are invo...
The suprachiasmatic nucleus (SCN) is the locus of the main pacemaker for circadian behavioral rhythms. In common voles, variation in circadian behavioral rhythmicity correlates with vasopressin (AVP) immunoreactive cells in the SCN. Here we studied the immunostaining of four AVP linked Ca(2+)-dependent protein kinase C (PKC) isoforms (PKCalpha, PKC...
Decreased immunoreactivity has been reported for several neuropeptides in the aged suprachiasmatic nucleus (SCN). We compared somatostatin (SS) and substance P (SP) immunoreactivity (ir) in aged (20-26 months) and young (6 months) Wistar rats. The old rat SCN revealed a significant increase in SSir (2.6-fold) and SPir. The results show that not all...
Despite the prominent role of the Syrian hamster (Mesocricetus auratus) in studies of circadian rhythms, there are no data available on the temporal dynamics of the neuropeptide vasopressin (AVP), a major output system of the suprachiasmatic nucleus (SCN). We studied the hamster SCN-AVP system in vivo across the light period and in vitro using long...
European ground squirrels (Spermophilus citellus) in outside enclosures show suppressed circadian rhythmicity in body temperature patterns during the first days of euthermia after hibernation. This may reflect either gradual reappearance of circadian rhythmicity following suppressed functioning of the circadian system during hibernation, or it may...
A biological rhythm is called ultradian if its period is shorter than 24 hour. Ultradian rhythms have been observed in physiological functions, like cellular processes, respiraton, circulation, hormonal release and sleep stages, as well as in behavioral functions, often related to feeding patterns. Ultradian rhythms are characterized by diversity n...
Rats are known to display a temporary deficit in memory function 6 h after training on a learning task, a phenomenon known as the ‘Kamin effect’. Later studies showed that maximal retrieval recurs in 24 h intervals after a single training and implied the role of the circadian clock in the suppression of memory retrieval at non-24 h intervals. This...
We studied vasopressin (AVP) release patterns from organotypic suprachiasmatic nucleus (SCN) cultures obtained from circadian rhythmic and non-rhythmic voles. All eight SCN cultures made from non-rhythmic voles did not produce any circadian pattern in AVP release, while five out of six SCN cultures of rhythmic voles produced significant (circadian)...
We studied vasopressin (AVP) release patterns from organotypic suprachiasmatic nucleus (SCN) cultures obtained from circadian rhythmic and non-rhythmic voles. All eight SCN cultures made from non-rhythmic voles did not produce any circadian pattern in AVP release, while five out of six SCN cultures of rhythmic voles produced significant (circadian)...
Yellow wrasses (Halichoeres chrysus) show clear daily activity patterns. The fish hide in the substrate at (subjective) night, during the distinct rest phase. Initial entrainment in a 12h:12h light-dark (12:12 LD) cycle (mean period 24.02h, SD 0.27h, n = 16) was followed by a free run (mean period 24.42h, SD 1.33h) after transition into constant di...
The intrinsic properties of the suprachiasmatic nucleus (SCN), the site of the main circadian pacemaker in mammals, have recently been studied in vitro by means of organotypic slice culturing. So far, only neonatal rats and mice have been used for such developmental and functional analyses of the isolated pacemaker. Here, the authors present a comp...
This study is the first to demonstrate organotypic culturing of adult suprachiasmatic nuclei (SCN). This approach was used to obtain organotypic SCN cultures from adult vole brain with a previously determined state of behavioral circadian rhythmicity. We examined vasopressin (AVP) immunoreactivity in these organotypic slice cultures. AVP is one of...
Organotypic hypothalamic cultures of neonatal rats comprising the suprachiasmatic nuclei (SCN) produce stable 20 h release patterns of vasoactive intestinal polypeptide (VIP) and arginine-vasopressin (AVP). Compared with rats, voles show variably expressed circadian activity patterns. In this study we measured neuropeptidergic release patterns in o...
Aging leads to a decrease in circadian organization of behavior. Whether this general observation is related to the finding that in older subjects the arginine-vasopressin (AVP) system in the suprachiasmatic nucleus (SCN) has deteriorated is an unsolved question. Here we assessed circadian organization of running wheel behavior and numbers of AVP c...
Vasopressin (AVP) is a major neuropeptide in the suprachiasmatic nucleus, the mammalian hypothalamic circadian pacemaker. Protein kinase Cα is a putatively coupled intracellular messenger. Mean numbers of AVP- and protein kinase Cα-immunoreactive neurons were determined in the suprachiasmatic nucleus of common voles, entrained to a 12:12 h light-da...
We have studied the number of arginine-vasopressin (AVP)-immunoreactive (IR) cells in the suprachiasmatic nuclei (SCN) in common voles, Microtus arvalis, with a strong (n = 18), weak (n = 10) or absent (n = 9) expression of circadian rhythmicity. Spontaneous expression of rhythmicity was assessed from records of wheel running activity and general a...
In their ultradian (2- to 3-hr) feeding rhythm, common voles show intraindividual synchrony from day to day, as well as interindividual synchrony between members of the population, even at remote distances. This study addresses the question of how resetting of the ultradian rhythm, a prerequisite for such synchronization, is achieved. Common voles...
With this glossary, the authors neither claim completeness nor to give final definitions, but only to keep a common basis of phrasing in biological rhythms. We heavily drew from earlier vocabulaires to which we refer here explicitely (Aschoff et al. 1965; Halberg et al. 1977; Aschoff 1981)
Temporal order is crucial for all living beings. They have to accomplish manifold and recurring tasks, that are often mutually exclusive. Moreover, those tasks have to be fulfilled at the right time, in tune with periodic fluctuations in the environment. Biological rhythms play an important part in the temporal organization of behaviour and physiol...
The timing mechanism underlying ultradian (2-3 h) activity patterns in the common vole, Microtus arvalis, was studied using behavioral 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 behav...
Escape responses of common voles exposed either to a kestrel, Falco tinnunculus, model 'flown' overhead or to neighbouring voles from the same family responding to such a model were investigated. The majority of voles (81%) either froze or ran for cover when exposed to the sight of the kestrel model. Neighbouring conspecifics, who could not see the...
Effects of hypothalamic lesions on the ultradian and circadian organization of wheel running and feeding were studied in the common vole, Microtus arvalis. Circadian organization broke down within 30 days in continuous darkness in 24% of intact voles (n = 135). Ultradian rhythmicity of feeding (period 2-3 hr) persisted in constant conditions in all...
To study the effects of pinealectomy on the circadian rhythms of locomotor activity and feeding, European starlings (Sturnus vulgaris) were held in constant light (0.2 lux and 200 lux) and under constant temperature conditions. Locomotor activity was measured by means of perches with microswitches mounted underneath, and feeding with an infrared ph...
Perch hopping activity and food intake were recorded in starlings in different intensities of continuous illumination (LL), varying from 0.1 to 1000 lux. Circadian rhythmicity in perch hopping disappeared in 10 lux and all higher intensities. In contrast, freerunning circadian rhythms in feeding were always present. In low light intensities, the pe...
In a short but intense field investigation, surface activity of common voles in a cropped lucerne field was assayed by live-trapping while, simultaneously, hunting activity and yield of three species of raptors were recorded by continuous observation. Pronounced short-term rhithms in trappability of the vole population ran parallel with fluctuation...
The circadian pacemaker in the suprachiasmatic nucleus (SCN), has been implicated as playing a role in time dependent memory retrieval. To further elucidate this role we have studied the response to active shock avoidance (ASA) training on vasopressin (AVP) immunoreactivity (-ir) in the SCN. Selected house mouse lines with high and low SCN-AVP-ir w...