关于动物学实验课教学设计的新探讨

现代生物技术科学研究的快速发展与新成果的不断取得,使基础教学中动物学实验课的改革已成为必然。本文分析动物学实验课的特点,正是探讨如何应用现代教学设计理论来设计动物学实验课教学,以提高动物学实验课教与学的有效性。     

The influence of an elastic tendon on the force producing capabilities of a muscle during dynamic movements

With increasing computer power, computer simulation of human movement has become a popular research tool. However, time to complete simulations can still be long even on powerful computers. One possibility for reducing simulation time, with models of musculo-skeletal system, is to simulate the muscle using a rigid tendon rather than the more realistic compliant tendon. This study examines the effect of tendon elasticity on muscle force output under different dynamic conditions. A single muscle, point mass model was used and simulations were performed varying the mass, the tendon length, the initial position, and the task. For simulations for relatively slow motion, as experienced for example in upper limb reaching motions or rising from a chair, tendon properties had little influence on muscle force, in contrast simulations of an explosive task similar to jumping or throwing tendon had a much larger effect.     

Studies on the fine structure of invertebrate blood vessels

Summary The position, structure and function of the valves within the lateral sinus of the medical leech, Hirudo medicinalis, are described on the basis of vital, light- and electron microscopy. In this species the valvular apparatus consists of multiple elongated fir cone-shaped fibrous villi surrounding the orifices of the latero-lateral and latero-dorsal vessel like a tentacular crest. Each villus is covered by a thin sheet of a continuous endothelium. The valves prevent the backflow of hemolymph during systolic contraction of the lateral sinus.The endothelium contains many small mitochondria and polyribosomes in the perinuclear cytoplasm and it develops deep projections into the underlying connective tissue. Each of these consists of a multilayered system of closely interwoven thin endothelial membranes. The endothelium is anchored to its basement membrane by means of a great number of poorly defined hemidesmosomes. The fibrous tissue of the villi consists mainly of a homogeneous vitreous matrix in which few cellular components and very fine filaments are dispersed. Close to the endothelium this matrix appears to be condensed to form a multilayered framework made out of a basement membrane-like material.Though the valves themselves are devoid of muscle cells, those situated at their base and thus belonging to the vascular wall proper, display some specific morphological features: in particular the nuclei of these cells show a distinct fibrous lamina. Moreover, these muscle cells seem to be innervated only by one type of axon, containing both small, lucent synaptic vesicles as well as some of the dense-core variety.These findings are compared with data from earlier works and are discussed in relation to the hemodynamic functions of this valvular apparatus.     

The invertebrate fauna of High Arctic seabird nests: the microarthropod community inhabiting nests on Spitsbergen,Svalbard

The invertebrate fauna of the nests of three seabird species, black-legged kittiwakes (Rissa tridactyla), common eider (Somateria mollissima) and glaucous gull (Larus hyperboreus), were sampled in Kongsfjorden, Spitsbergen, Svalbard. The invertebrate community was species poor, consisting predominantly of the flea, Mioctenopsylla arctica arctica (Insecta: Siphonaptera), but with six species of oribatid mite (Acari: Oribatida), Diapterobates notatus, Oribatula tibialis, Ameronothrus lineatus, Hermannia reticulata, Trichoribates trimaculatus and Ceratoppia bipilis, plus an occasional mesostigmatid mite. No Collembola or ticks (Acari: Ixodidae) were observed. With the exception of M. arctica arctica, the fauna of seabird nests consisted of opportunistic microarthropod species rather than specialised nest-dwelling or bird parasitic species. Species diversity of soil oribatid mites was greater in nests of the common eider than compared to nests of the black-legged kittiwake, which may be related to the ground nesting behaviour of the common eiders. No rare or unusual microarthropod species for Svalbard were found in the seabird nests. The contentions that nests may facilitate microarthropod colonisation of High Arctic regions via bird phoresy by providing a high-quality habitat at the point of arrival, or that there might be a specialised microarthropod fauna exploiting this habitat, were not supported in this study. These are amongst the first data on the microarthropod community of seabird nests in the High Arctic.     

The overshoot phenomenon in cotransport

Based on simplified equations, the overshoot curve experimentally observed with Na⁺-linked cotransport of neutral substrate (sugars or amino acids) has been simulated by computer. The approach is in principle similar to that of previous approaches (Weiss, S.D., McNamara, P.D. and Segal, S. (1981) J. Theor. Biol. 91, 597–608), but more general; in particular, it includes the effect of electrical membrane potential difference, and the quantitative relationship between height of peak and certain transport parameters, such as maximum rate, dissociation constant of ternary complex, electric charge of translocator, respectively. In addition, it tests two alternative models with respect to the rate-determining step: the translocation, on the one hand, and the association/dissociation of the ligands at the translocator site, on the other. The major findings are the following: (1) An overshoot can be obtained similar to that usually found experimentally, provided that maximum rate and affinity between translocator and transport of solute exceed certain minimum values. (2) The overshoot effect with Na-linked cotransport is enhanced by a negative membrane potential (inside relative to outside) and decreased by a positive potential. In the first case, the peak is higher and occurs faster. In the latter case, the peak is lower and delayed. (3) The effect of an electric potential difference on the overshoot curve does not depend appreciably on the charge of the empty translocator, except if the translocation of the latter is strongly rate-limiting. (4) To obtain an overshoot curve, it is not necessary that the translocation step be rate-limiting, contrary to what has been postulated previously (Läuger, P. (1980) J. Membrane Biol. 57, 163–178).     

The challenges of understanding glycolipid functions: An open outlook based on molecular simulations

Glycolipids are the most complex lipid type in cell membranes, characterized by a great diversity of different structures and functions. The underlying atomistic/molecular interactions and mechanisms associated with these functions are not well understood. Here we discuss how atomistic and molecular simulations can be used to shed light on the role of glycolipids in membrane structure and dynamics, receptor function, and other phenomena related to emergence of diseases such as Parkinson's. The cases we discuss highlight the challenge to understand how glycolipids function in cell membranes, and the significant added value that one would gain by bridging molecular simulations with experiments. This article is part of a Special Issue entitled Tools to study lipid functions.     

The Demand for and Supply of Field Biologists

The first-year zoology course at University College Cardiff is based on a self-instructional system using printed texts, audiovisual programmes, and integrated practical work. Each course ‘Unit’ has in addition a ‘General Session’ in the lecture theatre and structured tutorial work; some Units have associated fieldwork. The students work in a specially designed teaching laboratory and proceed at their own preferred time and pace. Each aspect of the course and its organization is described, with emphasis on the modifications to the original scheme which have been introduced during its first three years of existence in the light of experience.     

高校《普通动物学》教学中实施自主学习的探索

课堂教学是学生获取知识的主渠道,教会学生如何自主学习已经成为世界各国基础教育的根本任务之一。在现代社会自主学习是学习者所必备的重要能力之一,在课堂教学模式下,让学生走自主学习之路是学会学习的有效途径。作者对本校《普通动物学》课堂教学模式下实施自主学习现状进行了分析、对比、改进,目的在于培养学生自主学习的意识,增强自主学习能力,提高学习效率。结果证明学生在自主式教学模式下积极性被充分调动,学习成绩显著提高。     

开放实验室条件下的动物学实验教学改革新探

探讨了充分利用开放实验室进一步改革动物学实验教学的新方法：把开展大学生课题研究融入动物学实验教学、充分利用动物标本室加强动物学实验教学、以学生为主体调整动物学实验的教学内容以及结合相关产学研课题提高动物学实验教学的效率。结合实际条件激发学生学习的兴趣和参加实验的积极性,提高了实验效果,培养了学生的创新精神和实践能力。     

动物学野外实习管理模式探讨

动物学野外实习是生命科学各专业教学计划的重要组成部分。在总结二十多年来野外实习经验的基础上,参考国内外一些做法,提出动物学野外实习的管理模式,包括实习的学时及安排,实习时间、地点的选择,实习组织形式及其职能,实习纪律和要求,实习中的安全防护,实习动员和总结六个方面。     

The influence of touchdown conditions and contact phase technique on post-flight height in the straight handspring somersault vault

In vaulting the gymnast must generate sufficient linear and angular momentum during the approach and table contact in order to complete the rotational requirements in the post-flight phase. This study investigated the effects of touchdown conditions and contact technique on peak post-flight height of a straight handspring somersault vault. A planar seven-segment torque-driven computer simulation model of the contact phase in vaulting was evaluated by varying joint torque activation time histories to match three performances of a straight handspring somersault vault by an elite gymnast. The closest matching simulation was used as a starting point to optimise peak post-flight height of the mass centre for a straight handspring somersault. It was found that optimising either the touchdown conditions or the contact technique increased post-flight height by 0.1 m whereas optimising both together increased post-flight height by 0.4 m above that of a simulation matching the recorded performance. Thus touchdown technique and contact technique make similar contributions to post-flight height in the straight handspring somersault vault. Increasing touchdown velocity and angular momentum lead to additional post-flight height although there was a critical value of vertical touchdown velocity beyond which post-flight height decreased.     

Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab <Emphasis Type="Italic">Chasmagnathus granulata</Emphasis>

Chasmagnathus granulata is a South American crab occurring in estuarine salt marshes of the Brazilian, Uruguayan and Argentine coasts. Life history is characterized by an export strategy of its larval stages. I reviewed information on experimental manipulation of salinity during embryonic and larval development (pre- and posthatching salinities), and on habitat characteristics of C. granulata in order to determine potential effects of larval response to salinity in the field and to suggest consequences for the population structure. Local populations are spread over coastal areas with different physical characteristics. Benthic phases occupy estuaries characterized by different patterns of salinity variation, and release larvae to coastal waters characterized by strong salinity gradients. The zoea 1 of C. granulata showed a strong acclimatory response to low salinity. This response operated only during the first weeks of development (during zoeae 1 and 2) since subsequent larval survival at low posthatching salinities was consistently low. Larvae developing at low salinity frequently followed a developmental pathway with five instead of four zoeal stages. The ability to acclimate and the variability in larval development (i.e. the existence of alternative developmental pathways) could be interpreted as a strategy to buffer environmental variability at spatial scales of local or population networks. Early survivorship and production of larvae may be relatively high across a rather wide range of variability in salinity (5–32‰). Plastic responses to low salinity would therefore contribute to maintain a certain degree of population connectivity and persistence regardless of habitat heterogeneity. Electronic Publication     

Studying the activities of microorganisms in soil using slides

Two implanted slide techniques are described by which the activity of proteolytic bacteria and the growth of algae in the soil can be readily studied by school students using simple apparatus and methods. Variations are suggested for studying the effects of agricultural practices and environmental conditions on the soil bacteria and algae.     

The control of twisting somersaults

In the takeoff and early flight phase of a twisting somersault, joint coordination is based on feed-forward control whereas in the late stages of the flight phase configuration adjustments are made using feedback control to ensure accurate completion of the movement and appropriate landing orientation. The aim of this study was to use a computer simulation model of aerial movement to investigate the extent to which arm and hip movements can control twist and somersault rotation in the flight phase of a twisting somersault. Two mechanisms were considered for the control of twist in simulated target trampoline movements with flight times of 1.4 s. In the first case a single symmetrical arm adduction correction was made using delayed feedback control based on the difference between the twist rate in a perturbed simulation and the twist rate in a target movement comprising a forward somersault with 1½ twists. Final corrections were made using symmetrical arm abduction and hip flexion to adjust the twist and somersault angles. In the second case continual asymmetrical arm adduction/abduction adjustments were used to remove the tilt from a perturbed full twisting backward somersault using delayed feedback control based on twist angle and angular velocity. The first method was able to cope with perturbations to a forward somersault with 1½ twists providing the feedback time delay was less than 200 ms. The second method was able to correct a perturbed full twisting backward somersault providing the feedback time delay was less than 125 ms.     

在动物学实验教学中培养学生创新思维

1 动物学实验教学存在的问题和实行改革的必要 传统的动物学实验一般以形态解剖和动物分类为主,课程教学内容多为演示性和验证性实验.这些实验对培养学生的基本实验技能、基本实验方法、常用仪器的使用以及数据处理是十分必要的,但模式比较单一.教学中综合类、研究类实验几乎是空白,未能反映现代动物学新发展内容,这对培养学生科研和创新能力不利(乔淑芬,2007).因此,改造传统的实验教学内容和实验技术方法,建立新型的适应学生能力培养、鼓励探索的多元化实验教学模式、培养学生的创新能力是非常必要的.3     

The weight of the clan: Even in insects, social isolation can induce a behavioural syndrome

Social isolation has dramatic consequences on the development of individuals of many vertebrate species, and it induces a set of behavioural disturbances rending them unable to process environmental as well as social stimuli appropriately. We hypothesized that isolation syndrome is a ubiquitous trait of social life that can be observed in a wide array of species, including invertebrates. Here we report that gregarious cockroaches (Blattella germanica) reared in isolation showed (i) stronger exploration-avoidance, (ii) reduced foraging activity, (iii) reduced willingness to interact socially, and (iv) reduced ability to assess mating partner quality than conspecifics reared in groups. We demonstrate the occurrence of a behavioural syndrome induced by social isolation, similar to syndromes described in vertebrates, revealing the importance of social interactions and group-living in this non-eusocial insect species. We suggest that investigating social isolation effects on individual development should provide interesting results to assess social cohesion of species and thus constitute an additional tool for comparative studies focusing on the evolution of social life.     

基于计算机模拟的蛋白质分离纯化实验

利用数学建模的方法首次提出了衡量分离纯化效果优劣的定量指标——纯化效益;建立了便于应用推广的聚乙二醇(polyethyleneglycol,PEG)和硫酸铵沉淀分离纯化模型,并以海芋过氧化物酶分离纯化为例,对模型进行求解、应用和检验,求解最优实验试剂用量.     

A Study of the Biological Preferences of Secondary School Pupils in Israel

An interactive computer simulation was designed as an aid to those teaching evolutionary theory. The simulation was inspired by (tie example of industrial melanism in the peppered moth. A BBC microcomputer is used to present a variegated display overlaid with moth shapes, where the colour of some moths is more like that of the background display than others. The student adopts the role of predator, and uses a mouse-pointer to ‘kill’ as many moths as possible in 18 sec. Surviving moths 'breed' to produce the next generation. Since practical trials demonstrated that moths are killed as an inverse function of degree of crypsis, progressive evolution occurs through the generations. The program also stores moth colour frequency data and, at a point chosen by the user, plots histograms for each generation. Development problems, and the simulation's value as a teaching aid, are discussed.     

The effects of Mn2+ and Ca2+ on the prolonged depolarising after-potential in barnacle photoreceptor

We have studied the effects on the PDA of modifying intracellular and extracellular concentrations of Ca²⁺ and Mn²⁺. The effect of decreased Ca²⁺ concentration or addition of EGTA is mainly an increase in the PDA amplitude and length. Raising Ca²⁺ concentration using ruthenium red or high external Ca²⁺ has the opposite effect. The effect of Mn²⁺ is much more striking: In the presence of 50–100 mM Mn²⁺ the PDA is initially greatly depressed but can rise slowly for up to 20 or 30 s (in the dark) until it approaches its original amplitude and time course. Bridge measurements showed that the depression of the PDA corresponds to a depressed conductance and so is not due to an increase in K⁺ conductance. The Mn²⁺ effect is potentiated by decreased Ca²⁺. Appropriate stimulation suppresses the rising PDA as promptly as it does a normal PDA, suggesting that if lateral diffusion is the source of the slow rise, the PDA and PDA-depressing processes must be spatially linked. The action of the anti-PDA is apparently prolonged by both Ca²⁺ and Mn²⁺.Based on material presented at the European Neurosciences Meeting, Florence, September 1978