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1.
Seiichiro Kamisaka 《Biological Sciences in Space》2003,17(2):105-107
Organisms borne in the primitive sea about 30 million years ago had evolved in water without a large influence of gravity on earth. About 4 million years ago, the first terrestrial organisms, plants appeared on the land from the sea. The terrestrial plants have adapted to and evolved on the land environment so that they can extend their roots downward in soil and their shoots upward against 1 g gravity. At least two functions that were acquired during the process of evolution helped the terrestrial plants to adapt to gravity environment on earth. One is gravitropism. The other is the reinforcement of the cell wall, particularly the secondary cell wall. In the present feature articles, the molecular mechanism of the adaptation of terrestrial plants to gravity environment on earth will be reviewed, paying special attention to the mechanism of the genetic control of the signaling of gravity stimulus in gravitropism, automorphogenesis, genes involved in auxin transport, gravity effect on cell wall properties and gravimorphogenesis in terrestrial plants. 相似文献
2.
Cardús D 《Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology》1994,1(1):P19-P22
The history of manned space flight has repeatedly documented the fact that prolonged sojourn in space causes physiological deconditioning. Physiological deterioration has raised a legitimate concern about man's ability to adequately perform in the course of long missions and even the possibility of leading to circumstances threatening survival. One of the possible countermeasures of physiological deconditioning, theoretically more complete than others presently used since it affects all bodily systems, is artificial gravity. Space stations and spacecrafts can be equipped with artificial gravity, but is artificial gravity necessary? The term "necessary" must be qualified because a meaningful answer to the question depends entirely on further defining the purpose of space travel. If man intends to stay only temporarily in space, then he must keep himself in good physical condition so as to be able to return to earth or to land on any other planetary surface without undue exposure to major physiological problems resulting from transition through variable gravitational fields. Such a situation makes artificial gravity highly desirable, although perhaps not absolutely necessary in the case of relative short exposure to microgravity, but certainly necessary in interplanetary flight and planetary landings. If the intent is to remain indefinitely in space, to colonize space, then artificial gravity may not be necessary, but in this case the consequences of long term effects of adaptation to weightlessness will have to be weighed against the biological evolutionary outcomes that are to be expected. At the moment, plans for establishing permanent colonies in space seem still remote. More likely, the initial phase of exploration of the uncharted solar system will take place through successive, scope limited, research ventures ending with return to earth. This will require man to be ready to operate in gravitational fields of variable intensity. Equipping spacecrafts or space stations with some means of artificial gravity in this initial phase is, therefore, necessary without question. In a strict sense artificial gravity is conceived as a means of replacing natural gravity in space by the centripetal acceleration generated by some sort of rotating device. Rotating devices create an inertial force which has effects on bodies similar to those caused by terrestrial gravity, but artificial gravity by a rotation device is not the same as terrestrial gravity, as we shall see. Present research in artificial gravity for space exploration is projected in two main directions: artificial gravity for whole space stations and artificial gravity produced by short arm centrifuges designed for human use in space. 相似文献
3.
Oganov VS Tairbekov MG Ilyina VK 《Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology》2001,8(1):P9-11
Mechanical stimulation of bone tissue determined by earth gravity is one of the main factors mediating the nature, rate and direction of functional adaptation of the bone system in the process of onto- and phylogenesis. Theoretically expected losses of bone mass under condition of mechanical load deficit under microgravity (osteopenia, osteoporosis) may become a factor that limits the duration of space flights. As a result of long-term studies some properties and regularities of change in human tissue after prolonged space flights (for 5-7 months) were established. 相似文献
4.
Nemirovskaia TL Shenkman BS Krasnov IB 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2005,91(2):113-121
The space flight or simulated gravitational unloading lead to the muscle atrophy, slow-to-fast transformation of muscle fibers and myofibrillar damages both in humans and animals (1, 7, 13, 17). This process could be prevented by the exercise training during space flight (1), (partly) by periodic weight support during unloading (13). It has been demonstrated in these studies that there is some level of force production necessary for the maintenance of skeletal muscle properties. It is known that adaptation to the physical training frequently induces augmentation in cross-sectional area (CSA) of muscle fibers (MF), transformation of fibers, augmentation of mitochondrial volume density, and increase in absolute volume of myofibrillas. Numerous observations suggest importance of gravitational loading in regulating muscle mass. The centrifuging is believed to be useful for preventing muscle functional and structural losses under microgravity. But there are few studies designed to investigate effect of artificial gravity on the skeletal musculature (2, 7). Our objective was to investigate structural adaptation in slow-twitch soleus muscle (percentage of connective tissue and central nuclei, fiber size, myosin heavy chain isotope, myofibrillar proteins and mitochondria volume density) after 19 and 33 days of hypergravity. 相似文献
5.
Masamichi Yamashita Tomio Naitoh Richard J Wassersug 《Biological Sciences in Space》2002,16(4):245-270
We review here the scientific significance of the use of amphibians for research in gravitational biology. Since amphibian eggs are quite large, yet develop rapidly and externally, it is easy to observe their development. Consequently amphibians were the first vertebrates to have their early developmental processes investigated in space. Though several deviations from normal embryonic development occur when amphibians are raised in microgravity, their developmental program is robust enough to return the organisms to an ostensibly normal morphology by the time they hatch. Evolutionally, amphibians were the first vertebrate animal to come out of the water and onto land. Subsequently they diversified and have adaptively radiated to various habitats. They now inhabit aquatic, terrestrial, arboreal and fossorial niches. This diversity can be used to help study the biological effects of gravity at the organismal level, where macroscopic phenomena are associated with gravitational loading. By choosing different amphibian models and using a comparative approach one can effectively identify the action of gravity on biological systems, and the adaptation that vertebrates have made to this loading. Advances in cellular and molecular biology provide powerful tools for the study in many fields, including gravitational biology, and amphibians have proven to be good models for studies at those levels as well. The low metabolic rates of amphibians make them convenient organisms to work with (compared to birds and mammals) in the difficult and confined spaces on orbiting research platforms. We include here a review of what is known about and the potential for further behavioral and physiological researches in space using amphibians. 相似文献
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Does gravity drive circumnutation? One model ascribes hypocotylcircumnutation to a continuing series of geotropic responseseach of which overshoots thereby maintaining a sustained oscillation.However, some features of the observed movements are not easilyreconciled with the model. The critical feature of this modelis the requirement that circumnutation must exhibit an absolutedependence on a g-force. Experiments with Helianthns annum onhorizontal clinostats demonstrated an 80% reduction in the amplitudeof hypocotyl circumnutation (compared with upright plants atone g) although the oscillations continued at simulated "zerog". It is not certain that the clinostat environment adequatelysimulates the weightless environment of space but, if it does,we may expect a space experiment to demonstrate that hypocotylnutation in Helianthus annuus is not fully dependent on gravity. (Received October 13, 1978; ) 相似文献
9.
The evolution of the plastid chromosome in land plants: gene content, gene order, gene function 总被引:2,自引:0,他引:2
Wicke S Schneeweiss GM dePamphilis CW Müller KF Quandt D 《Plant molecular biology》2011,76(3-5):273-297
This review bridges functional and evolutionary aspects of plastid chromosome architecture in land plants and their putative ancestors. We provide an overview on the structure and composition of the plastid genome of land plants as well as the functions of its genes in an explicit phylogenetic and evolutionary context. We will discuss the architecture of land plant plastid chromosomes, including gene content and synteny across land plants. Moreover, we will explore the functions and roles of plastid encoded genes in metabolism and their evolutionary importance regarding gene retention and conservation. We suggest that the slow mode at which the plastome typically evolves is likely to be influenced by a combination of different molecular mechanisms. These include the organization of plastid genes in operons, the usually uniparental mode of plastid inheritance, the activity of highly effective repair mechanisms as well as the rarity of plastid fusion. Nevertheless, structurally rearranged plastomes can be found in several unrelated lineages (e.g. ferns, Pinaceae, multiple angiosperm families). Rearrangements and gene losses seem to correlate with an unusual mode of plastid transmission, abundance of repeats, or a heterotrophic lifestyle (parasites or myco-heterotrophs). While only a few functional gene gains and more frequent gene losses have been inferred for land plants, the plastid Ndh complex is one example of multiple independent gene losses and will be discussed in detail. Patterns of ndh-gene loss and functional analyses indicate that these losses are usually found in plant groups with a certain degree of heterotrophy, might rendering plastid encoded Ndh1 subunits dispensable. 相似文献
10.
Assessing the role of large herbivores in the structuring and functioning of freshwater and marine angiosperm ecosystems
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While large herbivores can have strong impacts on terrestrial ecosystems, much less is known of their role in aquatic systems. We reviewed the literature to determine: 1) which large herbivores (> 10 kg) have a (semi‐)aquatic lifestyle and are important consumers of submerged vascular plants, 2) their impact on submerged plant abundance and species composition, and 3) their ecosystem functions. We grouped herbivores according to diet, habitat selection and movement ecology: 1) Fully aquatic species, either resident or migratory (manatees, dugongs, turtles), 2) Semi‐aquatic species that live both in water and on land, either resident or migratory (swans), 3) Resident semi‐aquatic species that live in water and forage mainly on land (hippopotamuses, beavers, capybara), 4) Resident terrestrial species with relatively large home ranges that frequent aquatic habitats (cervids, water buffalo, lowland tapir). Fully aquatic species and swans have the strongest impact on submerged plant abundance and species composition. They may maintain grazing lawns. Because they sometimes target belowground parts, their activity can result in local collapse of plant beds. Semi‐aquatic species and turtles serve as important aquatic–terrestrial linkages, by transporting nutrients across ecosystem boundaries. Hippopotamuses and beavers are important geomorphological engineers, capable of altering the land and hydrology at landscape scales. Migratory species and terrestrial species with large home ranges are potentially important dispersal vectors of plant propagules and nutrients. Clearly, large aquatic herbivores have strong impacts on associated species and can be critical ecosystem engineers of aquatic systems, with the ability to modify direct and indirect functional pathways in ecosystems. While global populations of large aquatic herbivores are declining, some show remarkable local recoveries with dramatic consequences for the systems they inhabit. A better understanding of these functional roles will help set priorities for the effective management of large aquatic herbivores along with the plant habitats they rely on. 相似文献
11.
Charles W. Heckman 《International Review of Hydrobiology》1998,83(1):31-63
The results of a 3 1/2 year study in the Pantanal of Mato Grosso revealed that the life cycles of the invertebrates are profoundly influenced by the annual alternations between a period of very heavy rainfall and several months during which almost no rain falls. A very pronounced effect on the biota is the elimination of many species present in neighboring regions but without the ability to survive periods of adverse conditions resulting from the alternations between flood and dryness. However, those species with suitable adaptations are able to produce very large populations. The annual activity cycles of the invertebrates must not only be timed to the seasonal weather conditions but also to the activities of other species in the food web. They must be adapted to periods of surplus alternating with scarcity of food and predator pressure, which exert great influence on the development of the populations. Of the 256 species considered, most have the ability to produce offspring throughout the year whenever conditions are conducive, but there are also a considerable number which have life cycles apparently including only one reproductive period each year. The general effect of the seasonal changes on the aquatic community of the wetland is to greatly reduce species diversity but to allow the production of vast numbers of those species that have successfully adapted to the conditions. This adaptation of the aquatic species usually entails a dormant stage or a terrestrial one as well as a considerable rate of reproduction to offset losses during periods of unfavorable conditions. The invertebrate fauna includes several taxa represented overwhelmingly by cosmopolitan and circumtropical species, including Rotifera and Gastrotricha, but the great majority of the species are endemic to South America. 相似文献
12.
Some degree of wetland loss characterizes most coastal systems of the United States. This loss is generally reported as a decrease in wetland area, but most coastal land loss entails wetland submergence and conversion to open water. This concurrent increase in the area of aquatic habitat decreases the wetland:open water ratio, effectively diluting the area of remaining wetland relative to the aquatic system. The functional loss of intertidal wetlands to the ecosystem associated with this dilution effect may significantly alter ecological functions dependent on the interactive coupling of wetland and aquatic habitats. The magnitude of functional loss is strongly dependent on the wetland:water ratio of an estuary. In estuaries with open bay-type morphologies, the open water area is already large and functional loss of wetland by additional dilution may be only slightly greater than the areal wetland loss. Where estuaries are wetland-dominated, however, conversion of even a small percentage of wetland to water drastically alters the wetland:water ratio. In these cases, functional losses by dilution are much greater than the rate of areal wetland loss.In the Barataria Basin estuary, Louisiana, between 1967 and 1987, 15.4% of the salt marsh was lost (assuming a loss rate of 0.8% y–1 of the remaining marsh). We estimated that this 15% loss of salt marsh, by conversion to open water, may have resulted in a 27% reduction in the supply of inorganic nutrients and organic matter to the estuarine water column by the marsh, simply due to the dilution effects of the changed wetland:open water ratio. Functional losses of this magnitude may have serious implications to the estuarine ecosystem where intertidal wetlands support aquatic productivity by exporting nutrients and energy or where intertidal wetlands buffer aquatic eutrophication by importing excess nutrients and organic matter. It is conceivable that an estuary characterized by wetland loss may reach a point where, although some wetland remains, its functional value to the ecosystem is essentially gone. 相似文献
13.
Maintenance of fluid homeostasis is critical to establishing and maintaining normal physiology. The landmark discovery of
membrane water channels (aquaporins; AQPs) ushered in a new area in osmoregulatory biology that has drawn from and contributed
to diverse branches of biology, from molecular biology and genomics to systems biology and evolution, and from microbial and
plant biology to animal and translational physiology. As a result, the study of AQPs provides a unique and integrated backdrop
for exploring the relationships between genes and genome systems, the regulation of gene expression, and the physiologic consequences
of genetic variation. The wide species distribution of AQP family members and the evolutionary conservation of the family
indicate that the control of membrane water flux is a critical biological process. AQP function and regulation is proving
to be central to many of the pathways involved in individual physiologic systems in both mammals and anurans. In mammals,
AQPs are essential to normal secretory and absorptive functions of the eye, lung, salivary gland, sweat glands, gastrointestinal
tract, and kidney. In urinary, respiratory, and gastrointestinal systems, AQPs are required for proper urine concentration,
fluid reabsorption, and glandular secretions. In anurans, AQPs are important in mediating physiologic responses to changes
in the external environment, including those that occur during metamorphosis and adaptation from an aquatic to terrestrial
environment and thermal acclimation in anticipation of freezing. Therefore, an understanding of AQP function and regulation
is an important aspect of an integrated approach to basic biological research. 相似文献
14.
Takei Y Kawakoshi A Tsukada T Yuge S Ogoshi M Inoue K Hyodo S Bannai H Miyano S 《Journal of experimental zoology. Part A, Comparative experimental biology》2006,305(9):787-798
Fish endocrinologists are commonly motivated to pursue their research driven by their own interests in these aquatic animals. However, the data obtained in fish studies not only satisfy their own interests but often contribute more generally to the studies of other vertebrates, including mammals. The life of fishes is characterized by the aquatic habitat, which demands many physiological adjustments distinct from the terrestrial life. Among them, body fluid regulation is of particular importance as the body fluids are exposed to media of varying salinities only across the thin respiratory epithelia of the gills. Endocrine systems play pivotal roles in the homeostatic control of body fluid balance. Judging from the habitat-dependent control mechanisms, some osmoregulatory hormones of fish should have undergone functional and molecular evolution during the ecological transition to the terrestrial life. In fact, water-regulating hormones such as vasopressin are essential for survival on the land, whereas ion-regulating hormones such as natriuretic peptides, guanylins and adrenomedullins are diversified and exhibit more critical functions in aquatic species. In this short review, we introduce some examples illustrating how comparative fish studies contribute to general endocrinology by taking advantage of such differences between fishes and tetrapods. In a functional context, fish studies often afford a deeper understanding of the essential actions of a hormone across vertebrate taxa. Using the natriuretic peptide family as an example, we suggest that more functional studies on fishes will bring similar rewards of understanding. At the molecular level, recent establishment of genome databases in fishes and mammals brings clues to the evolutionary history of hormone molecules via a comparative genomic approach. Because of the functional and molecular diversification of ion-regulating hormones in fishes, this approach sometimes leads to the discovery of new hormones in tetrapods as exemplified by adrenomedullin 2. 相似文献
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Canessa E 《Journal of theoretical biology》2007,248(4):646-656
Since laws of physics exists in nature, their possible relationship to terrestrial growth is introduced. By considering the human body as a dynamic system of variable mass (and volume), growing under a gravity field, it is shown how natural laws may influence the vertical growth of humans. This approach makes sense because the non-linear percentile curves of different aspects of human physical growth from childhood to adolescence can be described in relation to physics laws independently of gender and nationality. Analytical relations for the dependence of stature, measured mass (weight), growth velocity (and their mix as the body mass index) on age are deduced with a set of common statistical parameters which could relate environmental, genetics and metabolism and different aspects of physical growth on earth. A relationship to the monotone smoothing using functional data analysis to estimate growth curves and its derivatives is established. A preliminary discussion is also presented on horizontal growth in an essentially weightless environment (i.e., aquatic) with a connection to the Laird-Gompertz formula for growth. 相似文献
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《Animal : an international journal of animal bioscience》2016,10(11):1749-1759
Agroecology uses natural processes and local resources rather than chemical inputs to ensure production while limiting the environmental footprint of livestock and crop production systems. Selecting to achieve a maximization of target production criteria has long proved detrimental to fitness traits. However, since the 1990s, developments in animal breeding have also focussed on animal robustness by balancing production and functional traits within overall breeding goals. We discuss here how an agroecological perspective should further shift breeding goals towards functional traits rather than production traits. Breeding for robustness aims to promote individual adaptive capacities by considering diverse selection criteria which include reproduction, animal health and welfare, and adaptation to rough feed resources, a warm climate or fluctuating environmental conditions. It requires the consideration of genotype×environment interactions in the prediction of breeding values. Animal performance must be evaluated in low-input systems in order to select those animals that are adapted to limiting conditions, including feed and water availability, climate variations and diseases. Finally, we argue that there is no single agroecological animal type, but animals with a variety of profiles that can meet the expectations of agroecology. The standardization of both animals and breeding conditions indeed appears contradictory to the agroecological paradigm that calls for an adaptation of animals to local opportunities and constraints in weakly artificialized systems tied to their physical environment. 相似文献
19.
Absence of rapid sensory adaptation in neocortex during information processing states 总被引:5,自引:0,他引:5
Castro-Alamancos MA 《Neuron》2004,41(3):455-464
One prominent feature of sensory responses in neocortex is that they rapidly adapt to increases in frequency, a process called "sensory adaptation." Here we show that sensory adaptation mainly occurs during quiescent states such as anesthesia, slow-wave sleep, and awake immobility. In contrast, during behavior-ally activated states, sensory responses are already adapted. For instance, during learning of a behavioral task, when an animal is very alert and expectant, sensory adaptation is mostly absent. After learning occurs, and the task becomes routine, the level of alertness lessens and sensory adaptation becomes robust. The primary sensory thalamocortical pathway of alert and expectant animals is in the adapted state, which may be required for adequate sensory information processing. 相似文献
20.
Patron J Stapley P Pozzo T 《Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology》2002,9(1):P167-P168
Human, like any other animal systems, moves in the terrestrial gravity field and must learn gravity-related motor strategies during his ontogenetic development. Considering continuous gravity action upon body segments, movement involves particular muscle activation patterns depending on body orientation to gravity. Gravitational-altered environments provided by parabolic flight or orbital space mission offer a great opportunity to investigate how gravity is taken into account in posture and movement planning. Indeed, in a context where the mechanical constraints are modified, movement execution involves that new muscular activity have to be produced. Almost, only few studies in microgravity environment are included electromyographic analysis and this parameter is generally used only to confirm modification of the muscular activation patterns. This study is focused to analyse the adaptation capacity of the brain to a modified gravitational environment. In this aim, EMG activity have been recorded during a whole body movement execution in both normo- and microgravity environment during parabolic flight. This procedure allowed us to analyse the EMG patterns recorded during the very first moments of weightlessness. In this study are reported the results of this analyse. 相似文献