Structure of adsorbed fibrinogen obtained by scanning force microscopy

It is shown that scanning force microscopy (SFM), operated in the attractive mode, can be used to obtain high resolution pictures of adsorbed fibrinogen molecules on solid surfaces, without the need for staining or special microscope grids. SFM also reveals the three-dimensional structure of the adsorbed molecules. Two forms of adsorbed fibrinogen are demonstrated on hydrophobic silicone dioxide surfaces; a trinodular about 60 nm long and a globular with about a 40 nm diameter. Polymeric networks formed after storage of the surface with adsorbed fibrinogen in PBS for 11 days are also shown. The SFM-results for the trinodular structure suggest the existence of loops or peptide chains extending outside the basic structure of the fibrinogen molecule.     

Film recording of the kinematics of dolphin swimming

An ingenious method for recording the forward motion of dolphins and decoding the pictures was elaborated. The method makes it possible to reproduce the trajectories of body points of a swimming dolphin from their positions on pictures.     

Slow excitation waves and mechanisms of polymorphic ventricular tachycardia in an experimental model: isolated walls of the right ventricle from rabbit and squirrel

The mechanism of polymorphic disturbances of the heart rhythm is studied on an experimental model, isolated ventricular preparations of ground squirrel and rabbit. Polymorphic arrhythmias are identified from habitus of the isolated preparation pseudoECGs mathematically derived from electrograms registered simultaneously at 32 endocardial and 32 epicardial points. The same electrograms allow one to visualize the excitation wave propagation along each of the preparation surfaces. The comparison of excitation wave pictures and corresponding pseudoECGs enabled us to reveal the conditions necessary and sufficient for polymorphism in heart rhythm disturbances. Polymorphic arrhythmias are due to changes in wave pictures in the regions of retarded excitation propagation.     

Dynamics of the electrical activity in the form of a vortex with a straight filament in ground squirrel heart

Attacks of tachysystolia have been studied, which were induced by premature stimuli (amplitude up to 4-5 diastolic thresholds, duration 4 ms) applied after a set of rectangular impulses (amplitude 2 diastolic thresholds, duration 4 ms, frequency 0.5 or 2 Hz). The spatial and temporal distribution of electrical potential throughout the surface of a thin (approximately 1 mm) preparation was registered by two multi-electrode arrays (32 unipolar electrodes each). One array recorded the distribution of electrical potential on the endocardial surface and the other, on the epicardial one. Wave isochronous pictures (maps) corresponding to spatial and temporal propagation of excitation on the surfaces of the preparation were reconstructed on the basis of electrograms registered on each of the surfaces. On the basis of these maps, the three-dimensional structure of scroll waves, including the location, direction and velocity of the shift of filament ends as well as the shape of the thread was analyzed. The analysis of the data obtained in our experiments allow one to conclude that, under tachysystolias caused by three-dimensional scroll wave with a straight filament, there occur the following kinds of wave thread movements: (1) the wave thread may change its location from turn to turn and on the whole be located at different angles to the preparation surfaces; (2) the wave thread may precess, when one of the filament end is "secured" on the surface and the other constantly changes its location on the opposite surface; (3) the wave thread may periodically intertwine (twisted filament) and untwine; (4) dimensions of the scroll wave kernels (sections of the filament on the surfaces) may change from turn to turn both simultaneously on both surfaces (endocardial and epicardial) and on one of them only; (5) the wave thread may curve when it goes within the wall from endocardial to epicardial surfaces; the curve may come rather close the surfaces of the myocardial tissue.     

A method to assess population changes in king penguins: the use of a Geographical Information System to estimate area-population relationships

During the last decades, king penguin (Aptenodytes patagonicus) populations have been reported to increase throughout most of their breeding range. In this study, we compared the results obtained from direct counts of incubating king penguins with the results yielded by the estimation of the change in area occupied by breeding birds at the Ratmanoff king penguin colony at the Kerguelen Islands. The area of the colony was determined using a Geographical Information System with a georeferencing extension on aerial pictures taken in 1963, 1985 and 1998. Individual king penguin were counted on the same pictures or pictures taken on the same day. The overall population increase between 1963 and 1998 was 733% while the colony area increased by 677%. This study indicates that monitoring change in colony size is a good indicator for detecting and monitoring large population changes in king penguins, in particular for remote colonies. The discrepancy between the two results may be from two different kinds of bias. Firstly, there could be a possible error in the estimation of the area occupied by the colony resulting from the georeferencing of oblique pictures, and secondly, the density of king penguins may also change with population number. This method, which only requires high-altitude pictures, also reduces the possible disturbance to breeding made by low- to medium-altitude flights. Accepted: 7 February 2000     

Studies of the fossil dinosaur bone in the scanning electron microscope.

A fossil dinosaur bone, 80 million years old, was subjected to investigation in the scanning microscope. The bone surfaces to be examined were prepared with appropritely modified methods used in the technique of replication in transmission electron microscopy. In the scanning microscope pictures of vascular canals were obtained. The walls of these canals were shown to be formed of collagen fibrils. Moreover, it was demonstrated that the internal surface of the canal wall is made up of bundles of collagen fibrils which run obliquely, corkscrewwise, and in the form of plexus to the long axis of tke canal; Besides, osteocytes of the dinosaur bone were isolated and pictures of their spatial structure together with characteristic points of departure of processes from the cell body were obtained.     

Monkey locomotion on inclined surfaces

Motion pictures were taken of a subadult, female squirrel monkey moving on level and inclined surfaces. The gaits for the various degrees of incline were compared. The noncontact periods were not affected by changes in inclination. The contact periods, which were inversely related to speed, were affected, by changes in slope and intersect constants. When the incline was steep the animal was forced to jump and zig-zag to retain its progression. The affect of inclination was advantageous at 16° and disadvantageous at higher and lower inclines. At the 16° inclination the animal's short fore legs and long hind legs held the body horizontal, cancelling the effect of the incline. It is reasoned that limb proportions may be adaptive for progression on inclined surfaces and that the locomotor niches for the various arboreal primates may be usefully categorized in terms of the inclinations of their substrates.     

Vector correlations in the F + HO → HF + O reaction and its isotopic variant

The F + H(D)O → HF(DF) + O reactions have been studied using quasi-classical trajectory (QCT) calculation method, based on the three different potential energy surfaces (PESs) of Gomez-Carrasco et al. (J Chem Phys 2004, 121:4605; J Chem Phys 2005, 123:114310; Chem Phys Lett 2007, 435:188). Facilitated with the analysis of the QCT results, the pictures for product scattering and product polarizations have been presented to investigate the vector correlations in the two reactions, with effects of isotope substitution and electronic state as well as collision energy being revealed at a chemical stereodynamical level.     

Neural Correlates of Processing Negative and Sexually Arousing Pictures

Recent work has questioned whether the negativity bias is a distinct component of affective picture processing. The current study was designed to determine whether there are different neural correlates of processing positive and negative pictures using event-related brain potentials. The early posterior negativity and late positive potential were greatest in amplitude for erotic pictures. Partial Least Squares analysis revealed one latent variable that distinguished erotic pictures from neutral and positive pictures and another that differentiated negative pictures from neutral and positive pictures. The effects of orienting task on the neural correlates of processing negative and erotic pictures indicate that affective picture processing is sensitive to both stimulus-driven, and attentional or decision processes. The current data, together with other recent findings from our laboratory, lead to the suggestion that there are distinct neural correlates of processing negative and positive stimuli during affective picture processing.     

Gaze differences in processing pictures with emotional content

The International Affective Picture System (IAPS) is a set of standardized emotionally evocative color photographs developed by NIMH Center for Emotion and Attention at the University of Florida. It contains more than 900 emotional pictures indexed by emotional valence, arousal and dominance. However, when IAPS pictures were used in studying emotions with the event-related potentials, the results have shown a great deal of variation and inconsistency. In this research arousal and dominance of pictures were controlled while emotional valence was manipulated as 3 categories, pleasant, neutral and unpleasant pictures. Two experiments were conducted with an eye-tracker in order to determine to what the participants turn their gaze. Participants were 25 psychology students with normal vision. Every participant saw all pictures in color and same pictures in black/white version. This makes 200 analyzed units for color pictures and 200 for black and white pictures. Every picture was divided into figure and ground. Considering that perception can be influenced by color, edges, luminosity and contrast and since all those factors are collapsed on the pictures in IAPS, we compared color pictures with same black and white pictures. In first eye-tracking IAPS research we analyzed 12 emotional pictures and showed that participants have higher number of fixations for ground on neutral and unpleasant pictures and for figure on pleasant pictures. Second experiment was conducted with 4 sets of emotional complementary pictures (pleasant/unpleasant) which differ only on the content in the figure area and it was shown that participants were more focused on the figure area than on the ground area. Future ERP (event related potential) research with IAPS pictures should take into consideration these findings and to either choose pictures with blank ground or adjust pictures in the way that ground is blank. For the following experiments suggestion is to put emotional content in the figure area and to use different non complementary pictures to see if there is difference between different emotional categories.     

“图启”教学模式在细胞生物学教学中的构建*

"图启"教学模式是以"图"为主线,培养教师的制图能力、学生的识图能力和学生的绘图能力,并将三者有机结合,即将教师的备课、理论授课、实践教学三个环节融为一体,最大限度地提高教学质量,提升学生的综合能力。本文论述了在细胞生物学教学中构建"图启"教学模式的方法和意义,为"图启"教学模式在生物学教学中的推广与实施奠定基础。     

Experimental validation of a phase-field model to predict coarsening dynamics of lipid domains in multicomponent membranes

Membrane phase-separation is a mechanism that biological membranes often use to locally concentrate specific lipid species in order to organize diverse membrane processes. Phase separation has also been explored as a tool for the design of liposomes with heterogeneous and spatially organized surfaces. These “patchy” liposomes are promising platforms for delivery purposes, however their design and optimization through experimentation can be expensive and time-consuming. We developed a computationally efficient method based on the surface Cahn–Hilliard phase-field model to complement experimental investigations in the design of patchy liposomes. The method relies on thermodynamic considerations to set the initial state for numerical simulations. We show that our computational approach delivers not only qualitative pictures, but also accurate quantitative information about the dynamics of the membrane organization. In particular, the computational and experimental results are in excellent agreement in terms of lipid domain area fraction, total lipid domain perimeter over time and total number of lipid domains over time for two different membrane compositions (DOPC:DPPC with a 2:1 M ratio with 20% Chol and DOPC:DPPC with a 3:1 M ratio with 20% Chol). Thus, the computational phase-field model informed by experiments has a considerable potential to assist in the design of liposomes with spatially organized surfaces, thereby containing the cost and time required by the design process.     

Species preference by infant macaques with controlled social experience

In Experiment 1, infant Japanese monkeys and rhesus monkeys were artificially reared in pairs with conspecific or heterospecific monkeys. Preferences of these monkeys for a variety of pictures of Japanese monkeys and rhesus monkeys were repeatedly tested during the first 1 or 2 years of life. The duration of lever-pressing responses to see those pictures was a measure of the preference. All monkeys, Japanese or rhesus, preferred pictures of rhesus monkeys to pictures of Japanese monkeys, without regard to their social experiences. Experiment 2, with an adult Japanese monkey as the subject, and Experiment 3, with different pictures as stimuli, suggested that this preference was not a consequence of any bias in the pictures used. In Experiment 4, a Japanese monkey reared by a rhesus foster mother and rhesus monkeys reared by Japanese monkey mothers received the same preference test. The Japanese monkey infant preferred to see pictures of rhesus monkeys. However, rhesus infants did not show clear species preferences. These results suggest that infants of both Japanese and rhesus monkeys have a native tendency to prefer to see physical characteristics of rhesus monkeys over Japanese monkeys.     

The electrocortical modulation effects of different emotion regulation strategies

The current event-related potential study investigated the modulation effects of different emotion regulation strategies on electrocortical responses. When watching negative or neutral pictures, participants were instructed to perform three tasks: cognitive reappraisal, expressive suppression and passive viewing. We found that negative pictures elicited a larger late positive potential (LPP) than neutral pictures. Moreover, processes involved in strategy also had an effect on LPP amplitude, which was indicated by a larger LPP in reappraisal compared with suppression and viewing tasks when neutral pictures were presented. After the influence of processes on LPP was excluded, results showed that reappraisal effectively decreased the emotion-enhanced LPP than suppression and viewing. The difference in regulatory effect may be determined by the underlying processing mechanism. A larger frontal-central component, N2, was observed in suppression than reappraisal and viewing, which suggested that it involved the processes focusing on behavioral response. While the larger LPP found in reappraisal implicated that it recruited cognitive processes focusing on the picture meaning.     

Chemiluminescence-based detection and comparison of protein amounts adsorbed on differently modified silica surfaces

The biological consequences of protein adsorption on biomaterial surfaces are considered to be of utmost importance for their biocompatibility. A new method based on amino group-labeling coupled to a chemiluminescence reaction for direct determination of proteins adsorbed on material surfaces was employed. This method was used to explore the effects of surface chemistry and surface roughness on protein adsorption in a silicon oxide model system. Corundum sandblasting was applied to silicon wafers to create roughened surfaces while immobilization of fluorocarbon-, hydrocarbon-, and poly(ethylene glycol)-containing silanes produced surfaces of varying wettability. The adsorption behavior of two complex body fluids, human serum and saliva, and of two purified components, human serum albumin and fibronectin, was strongly influenced by the surface parameters. A general tendency to higher amounts of adsorbed protein was found on roughened surfaces and modification with poly(ethylene glycol) or with fluorocarbon moieties reduced protein adsorption. The values obtained with the new method could be confirmed by a colorimetric determination of protein amounts adsorbed on identically modified silica beads and were in accordance with those previously reported utilizing established methods for protein quantification. The presented method, which was methodically simple to perform and allowed the simultaneous measurement of a large number of samples, may be of future value for high-throughput surveying of the protein adsorption characteristics of biomaterials.     

On the social nature of eyes: The effect of social cues in interaction and individual choice tasks

In an experimental setting, we applied a dual strategy to better understand the effect of pictures of eyes on human behavior. First, we investigated whether the effect of eyes was limited to interaction tasks in which the subjects' decisions influenced the outcomes of other subjects. We expanded the range of tasks to include individual choice tasks in which the subjects' decisions only influenced their own outcomes. Second, we investigated whether pictures of eyes were one of many social cues or were unique in their effect. We compared the effect of pictures of eyes with the effect of a different condition in which we presented the subjects with pictures of other students (peers). Our results suggest that the effect of pictures of eyes is limited to interaction tasks and that eyes should be considered distinct from other social cues, such as reminders of peers. While pictures of eyes uniformly enhanced pro-social behavior in interaction tasks, this was not the case for reminders of peers. Furthermore, the reminders of peers led to more rational behavior in individual choice tasks, whereas the effect of pictures of eyes was limited to situations involving interaction. Combined, these findings are in line with the claim that the effect of pictures of eyes on behavior is caused by a social exchange heuristic that works to enhance mutual cooperative behavior.     

A computer program for topographic analysis of biomolecular systems.

This program essentially generates a picture of a space filling molecular model. By precise simulation of the intersections between atoms, leaving out the 'hidden line', a good perspective is produced. Additional three dimensional information is provided by simulating reflection spots on the surface. This program has been used to visualise three dimensional surface features of biologically important molecules (e.g., valinomycin). With slight modification the program can be used to visualise enzyme active sites and receptor surfaces. It can also be used to create animated motion pictures of molecular dynamics.     

The perception of apparent movement

When two similar pictures, overlapping but slightly displaced, were projected on a screen in alternation, apparent movement could be seen. How similar must successive pictures be to give apparent movement? This is the 'correspondence problem'. Manipulations of the local and global correspondences between pictures included motion phenomena such as reversed apparent movement; a four-stroke oscillatory cycle which gave an illusion of continuous motion in one direction; edges defined by texture, stereoscopic depth, or flicker, kinetic edges; and wave motion. It was concluded that human motion perception may comprise two separate mechanisms. Local point-by-point correlations between pictures are detected by a relatively peripheral system, probably based on directonally selective neural units. More subtle global correspondences are analysed by a more cognitive system which extracts edges before it process motion.     

Rapid assessment of forest canopy and light regime using smartphone hemispherical photography

Hemispherical photography (HP), implemented with cameras equipped with “fisheye” lenses, is a widely used method for describing forest canopies and light regimes. A promising technological advance is the availability of low‐cost fisheye lenses for smartphone cameras. However, smartphone camera sensors cannot record a full hemisphere. We investigate whether smartphone HP is a cheaper and faster but still adequate operational alternative to traditional cameras for describing forest canopies and light regimes. We collected hemispherical pictures with both smartphone and traditional cameras in 223 forest sample points, across different overstory species and canopy densities. The smartphone image acquisition followed a faster and simpler protocol than that for the traditional camera. We automatically thresholded all images. We processed the traditional camera images for Canopy Openness (CO) and Site Factor estimation. For smartphone images, we took two pictures with different orientations per point and used two processing protocols: (i) we estimated and averaged total canopy gap from the two single pictures, and (ii) merging the two pictures together, we formed images closer to full hemispheres and estimated from them CO and Site Factors. We compared the same parameters obtained from different cameras and estimated generalized linear mixed models (GLMMs) between them. Total canopy gap estimated from the first processing protocol for smartphone pictures was on average significantly higher than CO estimated from traditional camera images, although with a consistent bias. Canopy Openness and Site Factors estimated from merged smartphone pictures of the second processing protocol were on average significantly higher than those from traditional cameras images, although with relatively little absolute differences and scatter. Smartphone HP is an acceptable alternative to HP using traditional cameras, providing similar results with a faster and cheaper methodology. Smartphone outputs can be directly used as they are for ecological studies, or converted with specific models for a better comparison to traditional cameras.     

The characterization of phagocytotic processes using morphometry

In electromicroscopic pictures, the percentage areas of erythrophagosomes in macrophages of the spleen were determined 2 and 5 h after application of diamide and iodoacetate treated erythrocytes. The increase in erythrophagosomes is significant if compared with controls. It is mainly seen in connection with the changes of the erythrocyte membrane caused by diamide and iodoacetate which lead to an increased IgG-binding to the erythrocyte surfaces. The overcritical IgG-load acts as an phagocytosis signal for the macrophages.