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1.
In addition to forward undulatory swimming, Gymnarchus niloticus can swim via undulations of the dorsal fin while the body axis remains straight; furthermore, it swims forward and backward in a similar way, which indicates that the undulation of the dorsal fin can simultaneously provide bidirectional propulsive and maneuvering forces with the help of the tail fin. A high-resolution Charge-Coupled Device (CCD) imaging camera system is used to record kinematics of steady swimming as well as maneuvering in G. niloticus. Based on experimental data, this paper discusses the kinematics (cruising speed, wave speed, cycle frequency, amplitude, lateral displacement) of forward as well as backward swimming and maneuvering. During forward swimming, the propulsive force is generated mainly by undulations of the dorsal fin while the body axis remains straight. The kinematic parameters (wave speed, wavelength, cycle frequency, amplitude) have statistically significant correlations with cruising speed. In addition, the yaw at the head is minimal during steady swimming. From experimental data, the maximal lateral displacement of head is not more than 1% of the body length, while the maximal lateral displacement of the whole body is not more than 5% of the body length. Another important feature is that G. niloticus swims backwards using an undulatory mechanism that resembles the forward undulatory swimming mechanism. In backward swimming, the increase of lateral displacement of the head is comparatively significant; the amplitude profiles of the propulsive wave along the dorsal fin are significantly different from those in forward swimming. When G. niloticus does fast maneuvering, its body is first bent into either a C shape or an S shape, then it is rapidly unwound in a travelling wave fashion. It rarely maneuvers without the help of the tail fin and body bending.  相似文献   

2.
蟋蟀精子表面LCA及ConA结合糖复合物的分布变化   总被引:8,自引:0,他引:8  
LCA and ConA-binding glycoconjugates on cricket (Teleogryllus emma) sperm surface were detected with fluorescence microscope after FITC labelling for better understanding of the distribution of glycoconjugates during spermatogenesis and spermiogenesis. FITC-LCA and FITC-ConA were bound on the spermatocytes, and their distribution changes in the process of spermiogenesis were observed .In the testis sperm, FITC-LCA and FITC-ConA were mainly bound on the head and neck region. That is different from the mark pattern of spermatophore sperm, in which the nucleus, neck region and front of the tail showed obvious fluorescence mark, especially the acrosome complex and neck region exhibited stronger mark. The mark patterns of FITC-LCA and FITC-ConA were similar,though the former was distinctly clearer than the latter. But a little difference still exists in both of them. For example in the ninth stage of spermatid, FITC-LCA mark is located on the spermatid head and neck region, and FITC-ConA mark on the spermatid head, neck and front of the tail region. When fixed germ cells were treated with PBS instead of lectin solution, or fixed cells were incubated with lectin solution, which have been treated with 0.1 mol/L specific sugar inhibitor, i.e.α-D-mannose for FITC-LCA and FITC-ConA, and α-D-glucose for FITC-ConA, no mark was observed on the cells. Those results indicate that FITC-LCA conjugated glycoconjugates has the α-D- mannose residue, and FITC-ConA conjugated glycoconjugates has the α-D-mannose and α-D-glucose residue. The investigations show that the changes in glycoconjugates distribution of cricket sperm is similar to those of other insects and mammals. The evidence exhibit that a common rule of the glycoconjugates distribution on the sperm surface is followed by most of animal sperm which may relate to the function of sperm physiology.  相似文献   

3.
CFD Simulation of Fish-like Body Moving in Viscous Liquid   总被引:1,自引:0,他引:1  
The study of fish-like bodies moving in liquid is an interesting and challenging research subject in the fields of biolocomotion and biomimetics. Typically the effect of tail oscillation on fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions. An understanding of the complexities of such flows is of interest not only to biologists but also to engineers interested in developing vehicles capable of emulating the high performance of fish propulsion and manoeuvring. In the present study, a computational fluid dynamic (CFD) simulation of a three-dimensional biomimetic fish-like body has been developed to investigate the fluid flows around this body when moving in a viscous liquid. A parametric analysis of the variables that affect the flow surrounding the body is presented, along with flow visualisations, in an attempt to quantify and qualify the effect that these variables have on the performance of the body. The analysis provided by the unsteady transient simulation of a fish-like body has allowed the flow surrounding a fish-like body undergoing periodic oscillations to be studied. The simulation produces a motion of the tail in the (x, y) plane, with the tail oscillating as a rigid body in the form of a sinusoidal wave.  相似文献   

4.
He YK  Xue WX  Sun YD  Yu XH  Liu PL 《Cell research》2000,10(2):151-160
The experiment was performed to evaluate the progenies of plant lines transgenic for auxin synthesis genes derived from Ri T-DNA.Four lines of the transgenic plants were self-crossed and the foreign auxin genes in plants of T5 generation were confirmed by Southern hybridization.Two lines,D1232 and D1653,showed earlier folding of expanding leaves than untransformed line and therefore had early initiation of leafy head.Leaf cuttings derived from plant of transgenic line D1653 produced more adventitious roots than the control whereas the cuttings from folding leaves had much more roots than rosette leaves at folding stage,and the cuttings from head leaves had more roots than rosette leaves at heading stage.It is demonstrated that early folding of transgenic leaf may be caused by the relatively higher concentration of auxin.These plant lines with auxin transgenes can be used for the study of hormonal regulation in differentiation and development of plant orgens and for the breeding of new variety with rapid growth trait.  相似文献   

5.
There are 7 species of pangolin in the world. This paper deah with the measurement of some morphology indices in Manis petadactyla and Mania javanica. Measured variables included the body weight, the total body length, the length of head and body, the length of tail,the length of protruding rim of external ear, the length of hind feet, the length of middle claws of fore feet, the length of middle claws of hind feet, the number of rows of scales round mid-body, the number of single flank scales of edge tail. All variables measured were compared respectively between this 2 species. The results indicated that: ( 1 ) there were no signifieant differences in body weight and length of hind feet between this 2 species, but differences in the other variables were extremely significant. (21 The ratio of the length of middle claws of hind feet and fore feet in Mania pentadactyla was less than 1/2 ( n = 48 ), while Mania jaw, nica was more than 1/2 ( n = 15 ) ; the length of protruding rim of external ear in Mania pentadactyla was over 10 mm { n = 38 ), whereas Manis javanica was under 10 mm { n = 13 ) ; the number of single flank scales of edge tail in Mania pentadactyla was not beyond 21 (n = 65), and Mania javanica exeeeded 21 (n = 14) . So the ratio of the length of middle claws of hind feet and fore feet, the length of protruding rim of external ear, arid the ntunber of single flank scales of edge tail should be regard as distinctive features and taxonomic indices between this 2 species. (3) The relationships between body weight ( Y) and the total body length, the length of head and body, the length of tail {X) were positive correlation, and satisfied relation equation Y= aX^b.  相似文献   

6.
Interactions between ecological communities of herbivores and microbes are commonly mediated by a shared plant. A tripartite interaction between a pathogenic fungus-host plant-herbivorous insect is an example of such mutual influences. In such a system a fungal pathogen commonly has a negative influence on the morphology and biochemistry of the host plant, with consequences for insect herbivore performance. Here we studied whether the biotrophic fbngus Podosphaera ferruginea, attacking the great burnet Sanguisorba officinalis, affects caterpillar performance of the endangered scarce large blue butterfly Phengaris teleius. Our results showed that the pathogenic ftmgus affected the number and size of inflorescences produced by food-plants and, more importantly, had in direct, plant-mediated effects on the abun dance, body mass and immune response of caterpillars. Specifically, we found the relationship between caterpillar abundance and variability in inflorescence size on a plant to be positive among healthy food-plants, and negative among infected food-plants. Caterpillars that fed on healthy food-plants were smaller than those that fed on infected food-plants in one studied season, while there was no such difference in the other season. We observed the relationship between caterpillar immune response and the proportion of infected great burnets within a habitat patch to be positive when caterpillars fed on healthy food-plants, and negative when caterpillars fed on infected food-plants. Our results suggest that this biotrophic fungal infection of the great burnet may impose a significant indirect influence on P. teleius caterpillar performance with potential consequences for the population dynamics and structure of this endangered butterfly.  相似文献   

7.
This paper addresses the design of a biomimetic fish robot actuated by piezoeeramic actuators and the effect of artificial caudal fins on the fish robot's performance. The limited bending displacement produced by a lightweight piezocomposite actuator was amplified and transformed into a large tail beat motion by means of a linkage system. Caudal fins that mimic the shape of a mackerel fin were fabricated for the purpose of examining the effect of caudal fm characteristics on thrust production at an operating frequency range. The thickness distribution of a real mackerel's fin was measured and used to design artificial caudal fins. The thrust performance of the biomimetic fish robot propelled by fins of various thicknesses was examined in terms of the Strouhal number, the Froude number, the Reynolds number, and the power consumption. For the same fm area and aspect ratio, an artificial caudal fin with a distributed thickness shows the best forward speed and the least power consumption.  相似文献   

8.
The mechanical properties of the skull and the anti-shock characteristics of woodpecker's head were investigated by ex- periment and numerical simulation. We measured the micro-Young's modulus of the skull by nano-indentation method and calculated the macro-equivalent Young's modulus of the skull at different positions using homogenization theory. Based on the Computerized Tomography (CT) images of woodpecker head, we then built complete and symmetric finite element models of woodpecker's skull and its internal structure and performed modal analysis and stress spectrum analysis. The numerical results show that the application of pre-tension force to the hyoid bone can increase the natural frequency of woodpecker's head. The first natural frequency under the pre-tension force of 25 N reaches 57 Hz, which is increased by 21.3% from the non-pre-tension state and is more than twice the working frequency of woodpecker (20 Hz 25 Hz). On the application of impact force to the tip of beak for 0.6 ms, high magnitudes of stress component occur at around 100 Hz and 8,000 Hz, far away from both the working frequencies and the natural frequencies of woodpecker head. The large gaps among the natural, working and stress response frequencies enable the woodpecker to effectively protect its brain from the resonance injury.  相似文献   

9.
Wang J  Sha L Q  Li J Z  Feng Z L 《农业工程》2008,28(8):3574-3583
Soil carbon stored on the Tibetan Plateau appears to be stable under current temperature, but it may be sensitive to global warming. In addition, different grazing systems may alter carbon emission from subalpine meadow ecosystems in this region. Using a chamber-closed dynamic technique, we measured ecosystem respiration (ER) and soil respiration (SR) rates with an infrared gas analyzer on a perennial grazing meadow (PM) and a seasonal grazing meadow (SM) of Shangri-La in the Hengduan Mountain area. Both PM and SM showed strong unimodal seasonal variations, with the highest rates in July and the lowest in January. Significant diurnal variations in respiration were also observed on PM, affected mainly by air and soil temperatures, with the highest rates at 14:00 and the lowest before dawn. Both ER and SR rates were higher on PM than on SM from June to October, suggesting that the higher grazing pressure on PM increased respiration rates on subalpine meadows. The exponential model F = aebT<,/sup> of soil temperature (T) explained the variation in respiration better than the model of soil moisture (W) (R2 = 0.50–0.78, P < 0.0001), while the multiple model F = aebT<,/sup>Wc gave better simulations than did single-factor models (R2 = 0.56–0.89, P < 0.0001). Soil respiration was the major component of ER, accounting for 63.0%–92.7% and 47.5%–96.4% of ER on PM and SM, respectively. Aboveground plant respiration varied with grass growth. During the peak growing season, total ecosystem respiration may be dominated by this above-ground component. Long-term (annual) Q10 values were about twice as large as short-term (one day) Q10. Q10 at different time scales may be controlled by different ecological processes. The SM had a lower long-term Q10 than did the PM, suggesting that under increased temperature, soil carbon may be more stable with reduced grazing pressure.  相似文献   

10.
PAEs have been proved to be one of the major organic pollutants. The present study determined the level of PAEs using surface water samples from the upper reaches of the Yangtze River. The results showed that DEHP contributed the most to PAEs pollution, followed by DBP. Risk Quotients of PAEs were used for preliminary screening, and DEHP and BBP were identified as potential risk factors with RQ of 310 and 70.7. The MOS10 of DEHP and BBP were 1.40 and 1.32×105, respectively, indicating that BBP may pose little risk to aquatic organisms. The potential risk of DEHP was further analyzed with joint probabilistic curves. Among different biological groups, fish and zoobenthos were two major groups sensitive to DEHP-induced damage under current concentrations with 99.4% and 98.3% for 5% species of each group. While among the toxicity endpoints, reproduction may be more sensitive than others. The 5% and 10% aquatic species were suffered from reproductive damages by 100% and 97.8%, respectively. Overall, our results indicated that DEHP in the surface water of the upper Yangtze River may pose potential risk to aquatic organisms, especially on their reproduction. Therefore, more concerns should be paid in species protection and environmental management. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.  相似文献   

11.
By nature,biomarker is the measurable change associated with a physiological or pathophysiological process.Unlike blood which has mechanisms to minimize changes and to keep the internal environment homeostatic,urine is more likely to reflect changes of the body and is a better biomarker source.Because of its potential in biomarker discovery,urinary proteins should be preserved comprehensively as the duration of the patients’corresponding medical records.Here,we propose a method to adsorb urinary proteins onto a membrane we named Urimem.This simple and inexpensive method requires minimal sample handling,uses no organic solvents,and is environmentally friendly.Urine samples were filtered through the membrane,and urinary proteins were adsorbed onto the membrane.The proteins on the membrane were dried and stored in a vacuum bag,which keeps the protein pattern faithfully preserved.The membrane may even permit storage at room temperature for weeks.Using this simple and inexpensive method,it is possible to begin preserving urine samples from all consenting people.Thus,medical research especially biomarker research can be conducted more economically.Even more objective large-scale prospective studies will be possible.This method has the potential to change the landscape of medical research and medical practice.  相似文献   

12.
Body surface area(BSA)was regarded as a more readily quantifiable parameter relative to body mass in the normalization of comparative biochemistry and physiology.The BSA prediction has attracted unceasing research back more than a century on animals,especially on humans and rats.Few studies in this area for anurans were reported,and the equation for body surface area(S)and body mass(W):S=9.9 W 0.56,which was concluded from toads of four species in 1969,was generally adopted to estimate the body surface areas for anurans until recent years.However,this equation was not applicable to Odorrana grahami.The relationship between body surface area and body mass for this species was established as:S=15.4 W 0.579.Our current results suggest estimation equations should be used cautiously across different species and body surface area predictions on more species need to be conducted.  相似文献   

13.
bstract Biomarker is the measurable change associated with a physiological or pathophysiological process. Unlike blood which has mechanisms to keep the internal environment homeostatic,rine is more likely to reflect changes of the body. As a result, urine is likely to be a better biomarker ource than blood. However, since the urinary proteome is affected by many factors, including iuretics, careful evaluation of those effects is necessary if urinary proteomics is used for biomarker iscovery. Here, we evaluated the effects of three commonly-used diuretics(furosemide, F; hydrochlorothiazide,H; and spirolactone, S) on the urinary proteome in rats. Urine samples were collected before and after intragastric administration of diuretics at therapeutic doses and the roteomes were analyzed using label-free liquid chromatography–tandem mass spectrometry LC–MS/MS). Based on the criteria of P 6 0.05, a fold change P2, a spectral count P5, and false ositive rate(FDR) 61%, 14 proteins(seven for F, five for H, and two for S) were identified by rogenesis LC–MS. The human orthologs of most of these 14 proteins are stable in the healthy uman urinary proteome, and ten of them are reported as disease biomarkers. Thus, our results uggest that the effects of diuretics deserve more attention in future urinary protein biomarker tudies. Moreover, the distinct effects of diuretics on the urinary proteome may provide clues to  相似文献   

14.
15.
<正> Throughout the animal kingdom there are species that have two or more phenotypic forms or 'morphs', and many ofthese are amphibians. In North America, the red-backed salamander Plethodon cinereus can have either a red dorsal stripe or nodorsal stripe (lead-phase form), and evidence to date indicates the lead-phase form incurs a greater number of attacks from predators.In a recent collection of 51 P. cinereus, blood smears of both color morphs (35 red-stripe, 16 lead-phase) were examined toobtain numbers of circulating leukocytes (via light microscopy), which can be used to indirectly estimate levels of stress hormonesin vertebrates via a 'hematological stress index', which is the ratio between the number of two leukocyte types (neutrophilsand lymphocytes). Our results showed that lead-phase salamanders tended to have greater numbers of circulating neutrophils andlower numbers of circulating lymphocytes than red-stripe morphs, leading to higher average neutrophil-lymphocyte ratios inlead-phase individuals. Since the salamanders were held (refrigerated) for 7 days before sampling, we cannot be certain if this effectis a stress reaction to the captivity or the normal level for this morph. However comparison with two sets of related salamandersthat were captured and sampled immediately indicates the red-stripe salamanders were either not stressed from the captivityat all, or their white blood cell distributions had returned to normal after 7 days of captivity. Taken together, our results indicatethat lead-phase forms of P. cinereus have higher stress levels than the red-stripe forms, which may be a consequence of theirhigher exposure to, and/or attacks from, predators. They may also indicate that the lead-phase form is less-suited to captivity thanthe red-stripe form of this species  相似文献   

16.
Abstract Male body size can play an important role in the mating systems of anuran amphibians. We conducted labora- tory-based trials with cane toads Rhinella (Bufo) marina from an invasive population in the wet-dry tropics of northern Australia, to clarify the effects of a male's body size on his reproductive success and behavior (mate choice). Males were stimulated with a synthetic hormone to induce reproductive readiness. Larger body size enhanced a male toad's ability to displace a smaller rival from amplexus, apparently because of physical strength: more force was required to dislodge a larger than a smaller amplectant male. A male's body size also affected his mate-choice criteria. Males of all body sizes were as likely to attempt amplexus with another male as with a female of the same size, and preferred larger rather than smaller sexual targets. However, this size prefe- rence was stronger in larger males and hence, amplexus was size-assortative. This pattern broke down when males were given access to already-amplectant male-female pairs: males of all body sizes readily attempted amplexus with the pair, with no size discrimination. An amplectant pair provides a larger visual stimulus, and prolonged amplexus provides a strong cue for sex iden- tification (one of the individuals involved is almost certainly a female). Thus, a male cane toad's body size affects both his ability to defeat rivals in physical struggles over females, and the criteria he uses when selecting potential mates, but the impacts of that selectivity depend upon the context in which mating occurs  相似文献   

17.
Hydrodynamic Analysis of C-start in Crucian Carp   总被引:2,自引:0,他引:2  
The kinematics of turning maneuvers of startled Crucian Carp (Carassius auratus) are presented. All escape response observed are C-type fast-starts. The position of the center of mass and the me,merit of inertia of the fish are calculated. The results show that the position of the center of mass is always at 35% of the length of the fish from the head and the position of the center of mass and rroment of inertia can be considered unchanged during C-start of Crucian Carp. Hydro-dynamic analysis of the C-start is given based on the kinematics data from our experiments. The C-start consists of three stages. In stage 1, the tail fin of fish rapidly flaps in one direction, and a large moment acts on the fish‘s body, which rotates around the center of mass with an angular acceleration. In stage 2, the tail fin flaps more slowly in the opposite direction at slower speed, the fish‘s body rotates around the center of mass with angular deceleration and the center of mass of the fish moves along an are. In stage 3, the moment approximately equals zero, the fish‘s body stops rotating and the center of mass the moves along a straight line.  相似文献   

18.
As an organophosphorus compound that frequently detected in water samples,triphenyl phosphate(TPhP)has been showed to have multiple toxicological effects on aquatic species.However,no attention has been paid to its potential impact on non-model amphibian species.Here,tadpoles of the Zhenhai brown frog(Rana zhenhaiensis)were exposed to different concentrations of TPh P(0,0.02 and 0.1 mg/L)throughout the developmental period to assess physiological and meta bolic impacts of TPh P exposure on amphibian larvae.After 30-day TPh P exposure,the developmental stage of tadpoles from the high-concentration treatment appeared to be more advanced than that from the other two treatments,but other measured traits(including body size,tail length and liver weight)did not differ among treatments.Metabolite profiles in tadpole livers based on liquid chromatographymass spectrometry(LC-MS)revealed a distinct metabolic disorder in exposed animals.Specifically,significant changes in various hepatic amino acids(such as glutamine,glutamate,valine and leucine)were observed.Overall,our results indicated that chronic TPhP exposure potentially caused developmental and hepatic physiological changes in R.zhenhaiensis tadpoles,although its impact on tadpole growth appeared to be minor.  相似文献   

19.
It is well known that herbivore-induced plant defenses alter host plant quality and can affect the behavior and performance of later arriving herbivores.Effects of sequential attacks by herbivores that either suppress or induce plant defenses are less well studied.We sequentially infested leaves of tomato plants with a strain of the phytophagous spider mite Tetranychus urticae that induces plant defenses and the closely related Tetranychus evansi, which suppresses plant defenses.Plant quality was quantified through oviposifion of both spider mite species and by measuring proteinase inhibitor activity using plant material that had been sequentially attacked by both herbivore species.Spider-mite oviposifion data show that T.evansi could suppress an earlier induction of plant defenses by T.urticae,and T.urticae could induce defenses in plants previously attacked by T.evansi in 1 day.Longer attacks by the second species did not result in further changes in oviposifion.Proteinase inhibitor activity levels showed that T.evansi suppressed the high activity levels induced by T.urticae to constitutive levels in 1 day,and further suppressed activity to levels similar to those in plants attacked by T.evansi alone.Attacks by T.urticae induced proteinase inhibitor activity in plants previously attacked by T.evansi,eventually to similar levels as induced by T.urticae alone.Hence,plant quality and plant defenses were significantly affected by sequential attacks and the order of attack does not affect subsequent performance,but does affect proteinase inhibitor activity levels.Based on our results,we discuss the evolution of suppression of plant defenses.  相似文献   

20.
The Egyptia n mon goose (Herpestes ichneumon Linn aeus, 1758) is a medium-sized car nivore that experienced remarkable geographic expansion over the last 3 decades in the Iberian Peninsula. In this study, we investigated the association of species-related and abiotic factors with spleen weight (as a proxy for immunocompete nee) in the species. We assessed the relationship of body con dition, sex, age, seas on, and envir onmental conditi ons with splee n weight established for 508 hunted specimens. Our results indicate that the effects of sex and season outweigh those of all other variables, including body condition. Spleen weight is higher in males than in females, and heavier spleens are more likely to be found in spring, coinciding with the highest period of investment in reproduction due to mating, gestation, birth, and lactation. Coupled with the absence of an effect of body condition, our findi ngs suggest that splee n weight variation in this species is mostly influe need by lifehistory traits linked to reproduction, rather than overall energy availability, winter immunoenhancement, or energy partitioning effects, and prompt further research focusing on this topic.  相似文献   

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