Behavioural variation in natural populations. V. Morphological correlates of locomotion in the garter snake (Thamnophis radix)

A series of morphologieal and locomotor performance variables was measured in a population of newborn garter snakes to determine whether performance capacity has a significant morphological basis in these animals. Morphological traits measured were body length and mass, number of body and tail vertebrae and numbers of vertebral abnormalities. Locomotor performances included burst and mid-distance speed and distance and time crawled before anti-predator displays were assumed. All performance variables were repeatable in daily replicate trials ( P < 0.001). Individual burst speed, mid-distance speed, and distance crawled were significantly correlated pairwise ( P < 0.01). Most morphological and performance variables had a significant mass dependence (static allometry), although the effects were rather weak ( r ² < 0.1, except for body length): larger animals performed better and had fewer abnormalities. There were significant associations between some morphological traits and locomotor performance. Morphological factors accounted for 19% of the variation in mid-distance speed and 14% of the variation in antipredator behavior by multiple regression analysis. Canonical correlation of all performance and morphological variables simultaneously accounted for 24% of the observed variation in performance. Numbers of body and tail vertebrae (assayed by scale counts) had an interactive effect on speed of locomotion.     

Mucociliary differentiation according to time in human nasal epithelial cell culture

Knowledge of the state of differentiation, cell phenotype, and expression of genes for mucus production at the time of study is important because these may vary at different times during the culture period. The primary purpose of this study was to determine whether the number of ciliated cells increases as a function of differentiation in NHNE cells. If we observed an increase in the number of ciliated cells, the composition ratio of ciliated and secretory cells according to the culture duration was determined. The levels of mucin and lysozyme secretion and their gene expression at this time were also examined. The presence of ciliated cells was not evident up to 2 days after confluence. However, 3.1 +/- 0.2 %, 7.4 +/- 0.5 %, and 14.5 +/- 0.6 % of the cells were ciliated on the 7th, the 14th, and the 28th day after confluence, respectively. Meanwhile, the percentage of secretory cells were 35.6 +/- 2.8 %, 32.8 +/- 2.5 %, 32.8 +/- 2.5 %, and 49.4 +/- 1.4 % on the 2nd, the 7th, 14th, and 28th day after confluence. The amount of secreted mucin showed an abruptly increasing pattern by the 14th day after confluence but showed no significant changes thereafter. The amount of secreted lysozyme increased as a function of differentiation. MUC5AC and MUC5B mRNA were mainly expressed between the 7th and the 14th day after confluence with relatively weak MUC8 and lysozyme expression. By the 28th day after confluence however, as the MUC5AC mRNA expression became weaker, MUC5B, MUC8, and lysozyme mRNA expression became stronger. In conclusion, we speculate that in in vitro studies with NHNE cells, the time point of treatment should vary according to the purpose of the study. In addition, the MUC5B and MUC8 gene may play an important role in mucin secretion in fully differentiated human nasal epithelial cells.     

Formulating gels for decreased mucociliary transport using rheologic properties: Polyacrylic acids

The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clerance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of apparent viscosity (η) and complex modulus (G^*) were found to be the most useful parameters in the identification of polyacrylic acid formulations capable of decreasing mucociliary transport rate (MTR). A narrow range of η and G^* values suitable for reducing mucociliary clearance, while remaining sufficiently fluid for intranasal administration, were identified. The correlations between the rheologic parameters of the polycarbophil gels and their mucociliary transport rates were used to identify other polyacrylic acid gels that also had suitable mucociliary clearance properties, demonstrating that these parameters can be used to direct the optimization of formulations using simple in vitro rheologic testing. Published: April 20, 2007     

Trunk orientation causes asymmetries in leg function in small bird terrestrial locomotion

In contrast to the upright trunk in humans, trunk orientation in most birds is almost horizontal (pronograde). It is conceivable that the orientation of the heavy trunk strongly influences the dynamics of bipedal terrestrial locomotion. Here, we analyse for the first time the effects of a pronograde trunk orientation on leg function and stability during bipedal locomotion. For this, we first inferred the leg function and trunk control strategy applied by a generalized small bird during terrestrial locomotion by analysing synchronously recorded kinematic (three-dimensional X-ray videography) and kinetic (three-dimensional force measurement) quail locomotion data. Then, by simulating quail gaits using a simplistic bioinspired numerical model which made use of parameters obtained in in vivo experiments with real quail, we show that the observed asymmetric leg function (left-skewed ground reaction force and longer leg at touchdown than at lift-off) is necessary for pronograde steady-state locomotion. In addition, steady-state locomotion becomes stable for specific morphological parameters. For quail-like parameters, the most common stable solution is grounded running, a gait preferred by quail and most of the other small birds. We hypothesize that stability of bipedal locomotion is a functional demand that, depending on trunk orientation and centre of mass location, constrains basic hind limb morphology and function, such as leg length, leg stiffness and leg damping.     

温度对赤拟谷盗爬行和起飞活动的影响

在不同温度下研究了赤拟谷盗Tribolium castaneum(Herbst)在固体物面、设定粮面、温度均匀的粮(小麦)柱和具有温度梯度粮柱内爬行扩散速度、起飞温度等.主要结果为:赤拟谷盗在17℃开始有爬行为,25℃开始有飞行行为,在15～25℃时水平爬行速度和15 ～ 20℃时竖直运动速度与温度呈显著正相关,在无障...     

苹果蠹蛾幼虫爬行特性

本文通过收集苹果和梨树上的蛀果模拟自然落果,研究了苹果蠹蛾Cydia pomonella(L.)脱果幼虫的爬行特性。结果发现,58.91%的幼虫钻出蛀果进行了爬行,而41.09%滞留于果堆内部;在进行爬行的幼虫中,50%的幼虫爬行距离在0～1m之间,95%的幼虫爬行距离在0～7m之间,这意味着在实际防治过程中,落果周围0到7m的范围都需要做防治处理,而0～1m的范围需要重点防治;幼虫在果堆放置后的0～25d持续脱果,表明当果园内有落果时需要马上及时清理;幼虫结茧的高度大部分在50cm以下,在实际防治过程中,树干缚带诱杀幼虫时应将诱集带设置在距地面0～0.5m的主干上,以保证落果幼虫也可以被诱集带捕获。     

Neuropeptide TPep action on salivary duct ciliary beating rate in the nudibranch molluscTritonia diomedea

Recently, in the marine molluscTritonia, a family of three peptides (TPep-NLS,-PLS,-PAR) from identified pedal ganglion neurons has been characterized and shown to regulate ciliary beat frequency in epithelia and isolated cells of the molluscan foot. In this study, using an antiserum raised against TPep-NLS, immunofluorescent labelling was observed in specific nerve cell bodies and axons in the buccal ganglia ofTritonia, as well as in axons leading to and innervating the salivary ducts, salivary glands, oesophagus and foregut. This pattern of innervation suggests that buccal ganglion neurons containing TPep control the beating rate of ciliated cells in feeding organs. Accordingly, TPeps were introduced to isolated ciliated salivary ducts. It was found that TPeps and serotonin increased the ciliary beat frequency of cells of the salivary duct similarly; other peptides (such as APep fromAplysia) had no such effect. Threshold sensitivity both for TPeps and serotonin was approximately 10⁻⁸ M, with maximal response occurring above 10⁻⁵ M. Taken together, these structural and physiological results suggest that TPep-like peptides are present in the salivary and other feeding organs ofTritonia and are involved in the regulation of salivary transport.     

The mechanism of ciliary stimulation by acetylcholine: roles of calcium, PKA, and PKG

Stimulation of ciliary cells through muscarinic receptors leads to a strong biphasic enhancement of ciliary beat frequency (CBF). The main goal of this work is to delineate the chain of molecular events that lead to the enhancement of CBF induced by acetylcholine (ACh). Here we show that the Ca(2+), cGMP, and cAMP signaling pathways are intimately interconnected in the process of cholinergic ciliary stimulation. ACh induces profound time-dependent increase in cGMP and cAMP concentrations mediated by the calcium-calmodulin complex. The initial strong CBF enhancement in response to ACh is mainly governed by PKG and elevated calcium. The second phase of CBF enhancement induced by ACh, a stable moderately elevated CBF, is mainly regulated by PKA in a Ca(2+)-independent manner. Inhibition of either guanylate cyclase or of PKG partially attenuates the response to ACh of [Ca(2+)](i), but completely abolishes the response of CBF. Inhibition of PKA moderately attenuates and significantly shortens the responses to ACh of both [Ca(2+)](i) and CBF. In addition, PKA facilitates the elevation in [Ca(2+)](i) and cGMP levels induced by ACh, whereas an unimpeded PKG activity is essential for CBF enhancement mediated by either Ca(2+) or PKA.     

Energy cost and efficiency of sculling a Venetian gondola

Oxygen uptake was measured on four male subjects during sculling gondolas at constant speeds from approximately 1 to approximately 3 m.s-1. The number of scullers on board in the different trials was one, two or four. Tractional water resistance (drag, D, N) was also measured in the same range of speeds. Energy cost of locomotion per unit of distance (C, J.m-1), as calculated from the ratio of O2 uptake above resting to, increased with v according to a power function (C = 155.2.v1.67; r = 0.88). Also D could be described as a power function of the speed: D = 12.3.v2.21; r = 0.94). The overall efficiency of motion, as obtained from the ratio of D to C, increased with speed from 9.2% at 1.41 m.s-1 to 14.5% at 3.08 m.s-1. It is concluded that, in spite of this relatively low efficiency of motion, the gondola is a very economic means. Indeed, at low speeds (approximately 1 m.s-1), the absolute amount of energy for propelling a gondola is the same as that for waking on the level at the same speed for a subject of 70 kg body mass.     

FORCE AND BENDING MOMENT OF THE CAUDAL MUSCLES IN THE SHORTFIN PILOT WHALE

Controversy has existed about the power stroke of cetacean locomotion. We therefore measured cross-sectional areas of the appropriate muscles of the tail and computed possible forces and bending moments. The muscle areas are approximately equal in size and a similar relationship holds for the caudal tendons. It appears that the hypoaxial and epiaxial muscles are capable of generating forces that are approximately equal. Thrust delivered in the upstroke and downstroke may therefore be equal.     

A unified theory for the energy cost of legged locomotion

Small animals are remarkably efficient climbers but comparatively poor runners, a well-established phenomenon in locomotor energetics that drives size-related differences in locomotor ecology yet remains poorly understood. Here, I derive the energy cost of legged locomotion from two complementary components of muscle metabolism, Activation–Relaxation and Cross-bridge cycling. A mathematical model incorporating these costs explains observed patterns of locomotor cost both within and between species, across a broad range of animals (insects to ungulates), for a wide range of substrate slopes including level running and vertical climbing. This ARC model unifies work- and force-based models for locomotor cost and integrates whole-organism locomotor cost with cellular muscle physiology, creating a predictive framework for investigating evolutionary and ecological pressures shaping limb design and ranging behaviour.