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1.
A current model suggests that magnetoreception of compass information starts with light-dependent primary processes. Light-dependency of magnetoreception is supported by behavioral experiments with homing pigeons and caged migratory birds. Three passerine species showed normal orientation under dim monochromatic light from the blue-green range of the spectrum, while they were disoriented under yellow and red light. A sevenfold increase in intensity and pre-exposure to specific wavelengths caused changes in behavior. The behavioral data indicate a complex relationship between the wavelength of light and magnetoreception, suggesting the involvement of more than one type of receptors. Extracellular recordings from the nucleus of the basal optic root and the tectum opticum identified units that responded to changes in magnetic North. Each unit showed a peak in a distinct spatial direction, so that the input of these units, processed collectively and integrated, would indicate compass directions. 相似文献
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Here, we provide evidence for a wavelength-dependent effect of light on magnetic compass orientation in Pelophylax perezi (order Anura), similar to that observed in Rana catesbeiana (order Anura) and Notophthalmus viridescens (order Urodela), and confirm for the first time in an anuran amphibian that a 90° shift in the direction of magnetic compass
orientation under long-wavelength light (≥500 nm) is due to a direct effect of light on the underlying magnetoreception mechanism.
Although magnetic compass orientation in other animals (e.g., birds and some insects) has been shown to be influenced by the
wavelength and/or intensity of light, these two amphibian orders are the only taxa for which there is direct evidence that
the magnetic compass is light-dependent. The remarkable similarities in the light-dependent magnetic compasses of anurans
and urodeles, which have evolved as separate clades for at least 250 million years, suggest that the light-dependent magnetoreception
mechanism is likely to have evolved in the common ancestor of the Lissamphibia (Early Permian, ~294 million years) and, possibly,
much earlier. Also, we discuss a number of similarities between the functional properties of the light-dependent magnetic
compass in amphibians and blue light-dependent responses to magnetic stimuli in Drosophila melanogaster, which suggest that the wavelength-dependent 90° shift in amphibians may be due to light activation of different redox forms
of a cryptochrome photopigment. Finally, we relate these findings to earlier studies showing that the pineal organ of newts
is the site of the light-dependent magnetic compass and recent neurophysiological evidence showing magnetic field sensitivity
in the frog frontal organ (an outgrowth of the pineal). 相似文献
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The radical pair model of magnetoreception predicts that magnetic compass orientation can be disrupted by high frequency magnetic fields in the Megahertz range. European robins, Erithacus rubecula, were tested under monochromatic 565 nm green light in 1.315 MHz fields of 0.48 T during spring and autumn migration, with 1.315 MHz being the frequency that matches the energetic splitting induced by the local geomagnetic field. The birds responses depended on the alignment of the oscillating field with respect to the static geomagnetic field: when the 1.315 MHz field was aligned parallel with the field lines, birds significantly preferred northerly directions in spring and southerly directions in autumn. These preferences reflect normal migratory orientation, with the variance slightly increased compared to control tests in the geomagnetic field alone or to tests in a 7.0 MHz field. However, in the 1.315 MHz field aligned at a 24° angle to the field lines, the birds were disoriented in both seasons, indicating that the high frequency field interfered with magnetoreception. These finding are in agreement with theoretical predictions and support the assumption of a radical-pair mechanism underlying the processes mediating magnetic compass information in birds. 相似文献
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Animals that guide directions of their locomotion or their migration routes by the lines of the geomagnetic field use either polarity or inclination compasses to determine the field polarity (the north or south direction). Distinguishing the two compass types is a guideline for estimation of the molecular principle of reception and has been achieved for a number of animal groups, with the exception of insects. A standard diagnostic method to distinguish a compass type is based on reversing the vertical component of the geomagnetic field, which leads to the opposite reactions of animals with two different compass types. In the present study, adults of the mealworm beetle Tenebrio molitor were tested by means of a two-step laboratory test of magnetoreception. Beetles that were initially trained to memorize the magnetic position of the light source preferred, during the subsequent test, this same direction, pursuant geomagnetic cues only. In the following step, the vertical component was reversed between the training and the test. The beetles significantly turned their preferred direction by 180 degrees. Our results brought until then unknown original findings that insects, represented here by the T. molitor species, use-in contrast to another previously researched Arthropod, spiny lobster-the inclination compass. 相似文献
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The currently discussed model of magnetoreception in birds proposes that the direction of the magnetic field is perceived by radical-pair processes in specialized photoreceptors, with cryptochromes suggested as potential candidate molecules mediating magnetic compass information. Behavioral studies have shown that magnetic compass orientation takes place in the eye and requires light from the blue-green part of the spectrum. Cryptochromes are known to absorb in the same spectral range. Because of this we searched for cryptochrome (CRY) in the retina of European robins, Erithacus rubecula, passerine birds that migrate at night. Here, we report three individually expressed cryptochromes, eCRY1a, eCRY1b, and eCRY2. While eCRY1a and eCRY2 are similar to the cryptochromes found in the retina of the domestic chicken, eCRY1b has a unique carboxy (C)-terminal. In light of the radical-pair model, our findings support a potential role of cryptochromes as transducers for the perception of magnetic compass information in birds. 相似文献
7.
Ludmila Oliveriusová Pavel Němec Zuzana Pavelková František Sedláček 《Die Naturwissenschaften》2014,101(7):557-563
Magnetoreception has been convincingly demonstrated in only a few mammalian species. Among rodents, magnetic compass orientation has been documented in four species of subterranean mole rats and two epigeic (i.e. active above ground) species—the Siberian hamster and the C57BL/6J mouse. The mole rats use the magnetic field azimuth to determine compass heading; their directional preference is spontaneous and unimodal, and their magnetic compass is magnetite-mediated. By contrast, the primary component of orientation response is learned in the hamster and the mouse, but both species also exhibit a weak spontaneous bimodal preference in the natural magnetic field. To determine whether the magnetic compass of wild epigeic rodents features the same functional properties as that of laboratory rodents, we investigated magnetic compass orientation in the bank vole Clethrionomys glareolus (Cricetidae, Rodentia). The voles exhibited a robust spontaneous bimodal directional preference, i.e. built nests and slept preferentially along the north-south axis, and deflected their directional preference according to a shift in the direction of magnetic north, clearly indicating that they were deriving directional information from the magnetic field. Thus, bimodal, axially symmetrical directional choice seems to be a common feature shared by epigeic rodents. However, spontaneous directional preference in the bank vole appeared to be more pronounced than that reported in the hamster and the mouse. These findings suggest that bank voles are well suited for future studies investigating the adaptive significance and mechanisms of magnetic orientation in epigeic rodents. 相似文献
8.
Light-Dependent Magnetoreception in Birds: Does Directional Information Change with Light Intensity?
Magnetic compass orientation in birds is based on light-dependent processes, with magnetoreception being possible only under
light containing blue and green wavelengths. To look for possible intensity-dependent effects we tested Australian silvereyes
during autumn migration under monochromatic green light (565 nm) produced by light-emitting diodes at various light levels.
At intensities of 0.0021 and 0.0075 W/m2, the birds showed normal activity and were oriented in their seasonally appropriate migratory direction. Under low light
of 0.0002 W/m2 the birds were less active; scatter increased, but they still oriented in their migratory direction. Under a high light level
of 0.0150 W/m2, however, the test birds showed a counterclockwise shift in direction, preferring west-northwest instead of north. This change
in behavior may reflect a change in the output of the magnetoreception system, resulting from a disruption of the natural
balance between the wavelengths of light.
Received: 18 June 1999 / Accepted in revised form: 20 September 1999 相似文献
9.
Pigeons were released at two sites of equal distance from the loft, one within a magnetic anomaly, the other in magnetically
quiet terrain, and their tracks were recorded with the help of GPS receivers. A comparison of the beginning of the tracks
revealed striking differences: within the anomaly, the initial phase lasted longer, and the distance flown was longer, with
the pigeons' headings considerably farther from the home direction. During the following departure phase, the birds were well
homeward oriented at the magnetically quiet site, whereas they continued to be disoriented within the anomaly. Comparing the
tracks in the anomaly with the underlying magnetic contours shows considerable differences between individuals, without a
common pattern emerging. The differences in magnetic intensity along the pigeons' path do not differ from a random distribution
of intensity differences around the release site, indicating that the magnetic contours do not directly affect the pigeons'
routes. Within the anomaly, pigeons take longer until their flights are oriented, but 5 km from the release point, the birds,
still within the anomaly, are also significantly oriented in the home direction. These findings support the assumption that
magnetically anomalous conditions initially interfere with the pigeons' navigational processes, with birds showing rather
individual responses in their attempts to overcome these problems. 相似文献
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Rapid advances in graphics computing and micro-engineering have offered new techniques for prenatal cardiac imaging. Some of them can be non-invasively applied to both clinical and laboratory settings, including dynamic three-dimensional echocardiography, myocardial Doppler imaging, harmonic ultrasound imaging, and B-flow sonography. With clinical constraints, a few others have been mainly used in laboratories, such as endoscopic ultrasound, magnetic resonance imaging and biomicroscopy. Appropriate use and co-use of these new tools will not only provide unique information for better clinical assessment of fetal cardiac disease but also offer new ways to improved understanding of cardiovascular development and pathogenesis. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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IntroductionGranularfixedfiltershavebeenwidelyusedinindustryduetomanyoftheiradvantages,suchashighcollectionefficiency,wear,corrosionandheatresistanceandsoon (D’Ottavio ,1978) .However ,onedrawbackofgranularfixedfiltersisthattheycannotworkcontinuouslyforalong… 相似文献
12.
Animals make use of the Earth’s magnetic field for navigation and regulation of vegetative functions; however, the anatomical
and physiological basis for the magnetic sense has not been elucidated yet. Our recent results from histology and X-ray analyses
support the hypothesis that delicate iron-containing structures in the skin of the upper beak of homing pigeons might serve
as a biological magnetometer. Histology has revealed various iron sites within dendrites of the trigeminal nerve, their arrangement
along strands of axons, the existence of three dendritic fields in each side of the beak with specific 3D-orientations, and
the bilateral symmetry of the whole system. Element mapping by micro-synchrotron X-ray fluorescence analysis has shown the
distribution of iron and its quantities. Micro-synchrotron X-ray absorption near-edge-structure spectroscopy has allowed us
to unambiguously identify maghemite as the predominating iron mineral (90 vs 10% magnetite). In this paper, we show that iron-based
magnetoreception needs the presence of both of these iron minerals, their specific dimensions, shapes, and arrangements in
three different subcellular compartments. We suggest that an inherent magnetic enhancement process via an iron-crusted vesicle
and the attached chains of iron platelets might be sufficient to account for the sensitivity and specificity required by such
a magnetoreceptor. The appropriate alignment between the Earth’s magnetic field and the maghemite bands would induce a multiple
attraction of the magnetite bullets perpendicular to the membrane, thus, triggering strain-sensitive membrane channels and
a primary receptor potential. Due to its 3D architecture and physicochemical nature, the dendritic system should be able to
separately sense the three vector components of the Earth’s local field, simultaneously—allowing birds to detect their geographic
position by the magnetic vector, i.e., amplitude and direction of the local magnetic field, irrespective of the animal’s posture
or movement and photoreception. 相似文献
13.
Sean O’Donnell 《Die Naturwissenschaften》2018,105(1-2):11
Directional climate change (global warming) is causing rapid alterations in animals’ environments. Because the nervous system is at the forefront of animals’ interactions with the environment, the neurobiological implications of climate change are central to understanding how individuals, and ultimately populations, will respond to global warming. Evidence is accumulating for individual level, mechanistic effects of climate change on nervous system development and performance. Climate change can also alter sensory stimuli, changing the effectiveness of sensory and cognitive systems for achieving biological fitness. At the population level, natural selection forces stemming from directional climate change may drive rapid evolutionary change in nervous system structure and function. 相似文献
14.
An experimental group of homing pigeons (Columba livia f. domestica) learned to associate food with a magnetic anomaly produced by bar magnets that were fixed to the bowl in which they received
their daily food ration in their home loft; the control group lacked this experience. Both groups were trained to search for
two hidden food depots in a rectangular sand-filled arena without obvious visual cues; for the experimental birds, these depots
were also marked with three 1.15 × 106 μT bar magnets. During the tests, there were two food depots, one marked with the magnets, the other unmarked; their position
within the arena was changed from test to test. The experimental birds searched within 10 cm of the magnetically marked depot
in 49% of the test sessions, whereas the control birds searched there in only 11% of the sessions. Both groups searched near
the control depot in 11 and 13% of the sessions, respectively. The significant preference of the magnetically marked food
depot by the experimental birds shows that homing pigeons cannot only detect a magnetic anomaly but can also use it as a cue
for locating hidden food in an open arena. 相似文献
15.
Rats use multiple sources of information to maintain spatial orientation. Although previous work has focused on rats’ use
of environmental cues, a growing number of studies have demonstrated that rats also use self-movement cues to organize navigation.
This review examines the extent that kinematic analysis of naturally occurring behavior has provided insight into processes
that mediate dead-reckoning-based navigation. This work supports a role for separate systems in processing self-movement cues
that converge on the hippocampus. The compass system is involved in deriving directional information from self-movement cues;
whereas, the odometer system is involved in deriving distance information from self-movement cues. The hippocampus functions
similar to a logbook in that outward path unique information from the compass and odometer is used to derive the direction
and distance of a path to the point at which movement was initiated. Finally, home base establishment may function to reset
this system after each excursion and anchor environmental cues to self-movement cues. The combination of natural behaviors
and kinematic analysis has proven to be a robust paradigm to investigate the neural basis of spatial orientation. 相似文献
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实验通过运行连续搅拌反应器(CSTR),对城市初级污泥的两步嗜热厌氧消化进行了研究。研究结果表明,同一步嗜热厌氧工艺相比,两步嗜热厌氧工艺运行稳定,具有更高的有机物降解率、病原体的杀灭率,多产出的甲烷气体不仅可以弥补由于预处理而额外消耗的能量,而且还有净能量剩余。 相似文献
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黄石市环境信息管理系统的开发与应用 总被引:3,自引:0,他引:3
从开发和应用的角度,详细阐述了在WebGIS技术支撑下,利用Java编程语言的方法开发出的黄石市环境信息管理系统开发的技术路线,体系结构,数据组织和系统模块的构建,该系统能够更好地降低环境空间数据采集成本,提高环境信息的共享程序和范围,实现污染源信息的实时查询和统计分析,提供多种总量控制的解决方案和多种专题图的编辑与管理工具,具有海量图库管理和模糊查询定位能力,此系统的建立,对于解决黄石市环境污染问题具有极大的社会效益和经济效益。 相似文献
20.
James J. Foster Shelby E. Temple Martin J. How Ilse M. Daly Camilla R. Sharkey David Wilby Nicholas W. Roberts 《Die Naturwissenschaften》2018,105(3-4):27
In recent years, the study of polarisation vision in animals has seen numerous breakthroughs, not just in terms of what is known about the function of this sensory ability, but also in the experimental methods by which polarisation can be controlled, presented and measured. Once thought to be limited to only a few animal species, polarisation sensitivity is now known to be widespread across many taxonomic groups, and advances in experimental techniques are, in part, responsible for these discoveries. Nevertheless, its study remains challenging, perhaps because of our own poor sensitivity to the polarisation of light, but equally as a result of the slow spread of new practices and methodological innovations within the field. In this review, we introduce the most important steps in designing and calibrating polarised stimuli, within the broader context of areas of current research and the applications of new techniques to key questions. Our aim is to provide a constructive guide to help researchers, particularly those with no background in the physics of polarisation, to design robust experiments that are free from confounding factors. 相似文献