不同视觉经验中zif268基因的表达模式

zif268基因编码一转录因子ZIF268. 在发育的视皮层中,zif268基因的表达模式受发育的调节. 在具有正常视觉经验的视皮层中,zif268基因有较高水平的表达. 视觉废置后,视皮层内该基因的表达水平显著降低. 通过视觉刺激可显著增强该基因的表达. 有关zif268基因表达模式的研究对于阐明该基因在哺乳动物视觉系统中的生理功能起到借鉴的作用.     

Visual Ecology and Perception of Coloration Patterns by Domestic Chicks

This article suggests how we might understand the way potential predators see coloration patterns used in aposematism and visual mimicry. We start by briefly reviewing work on evolutionary function of eyes and neural mechanisms of vision. Often mechanisms used for achromatic vision are accurately modeled as adaptations for detection and recognition of the generality of optical stimuli, rather than specific stimuli such as biological signals. Colour vision is less well understood, but for photoreceptor spectral sensitivities of birds and hymenopterans there is no evidence for adaptations to species-specific stimuli, such as those of food or mates. Turning to experimental work, we investigate how achromatic and chromatic stimuli are used for object recognition by foraging domestic chicks (Gallus gallus). Chicks use chromatic and achromatic signals in different ways: discrimination of large targets uses (chromatic) colour differences, and chicks remember chromatic signals accurately. However, detection of small targets, and discrimination of visual textures requires achromatic contrast. The different roles of chromatic and achromatic information probably reflect their utility for object recognition in nature. Achromatic (intensity) variation exceeds chromatic variation, and hence is more informative about change in reflectance – for example, object borders, while chromatic signals yield more information about surface reflectance (object colour) under variable illumination. This revised version was published online in July 2006 with corrections to the Cover Date.     

不同视觉经验中zif268基因的表达模式

zif268基因编码一转录因子ZIF268. 在发育的视皮层中,zif268基因的表达模式受发育的调节. 在具有正常视觉经验的视皮层中,zif268基因有较高水平的表达. 视觉废置后,视皮层内该基因的表达水平显著降低. 通过视觉刺激可显著增强该基因的表达. 有关zif268基因表达模式的研究对于阐明该基因在哺乳动物视觉系统中的生理功能起到借鉴的作用.     

Influence of Unrewarded Stimuli on the Classification of Visual Patterns by Honey Bees

Bees were trained to discriminate visual patterns in five experiments. The rewarded pattern (S+), was a 50-mm black disc in all experiments; the unrewarded pattern (S–) was varied. Subsequently bees were given a choice between different stimuli in order to discover what bees learnt about five attributes of the training stimuli. The attributes tested were size, contrast, color, ‘compactness’ vs. ‘dissectedness’ (tests with ring-patterns), and presence or absence of acute points (tests with discs, squares, triangles and stars). The significance of these attributes varied with the particular unrewarded pattern (S–) used in training (Figs. 1, 2). This is interpreted as a modification of the bee's selective attention to certain features during training. The results also indicate a difference in the salience of attributes. Differences in size or outline (presence of acute points) only influenced the bee's preference after a training that specifically required this distinction, while differences in contrast, colour and dissectedness were also significant when the training stimuli did not differ in that respect.     

Visual Implant Elastomer Mark Retention Through Metamorphosis in Amphibian Larvae

Abstract: Questions in population ecology require the study of marked animals, and marks are assumed to be permanent and not overlooked by observers. I evaluated retention through metamorphosis of visual implant elastomer marks in larval salamanders and frogs and assessed error in observer identification of these marks. I found 1) individual marks were not retained in larval wood frogs (Rana sylvatica), whereas only small marks were likely to be retained in larval salamanders (Eurycea bislineata), and 2) observers did not always correctly identify marked animals. Evaluating the assumptions of marking protocols is important in the design phase of a study so that correct inference can be made about the population processes of interest. This guidance should be generally useful to the design of mark-recapture studies, with particular application to studies of larval amphibians.     

Statistical Analysis Reveals Co-Expression Patterns of Many Pairs of Genes in Yeast Are Jointly Regulated by Interacting Loci

Expression quantitative trait loci (eQTL) studies have generated large amounts of data in different organisms. The analyses of these data have led to many novel findings and biological insights on expression regulations. However, the role of epistasis in the joint regulation of multiple genes has not been explored. This is largely due to the computational complexity involved when multiple traits are simultaneously considered against multiple markers if an exhaustive search strategy is adopted. In this article, we propose a computationally feasible approach to identify pairs of chromosomal regions that interact to regulate co-expression patterns of pairs of genes. Our approach is built on a bivariate model whose covariance matrix depends on the joint genotypes at the candidate loci. We also propose a filtering process to reduce the computational burden. When we applied our method to a yeast eQTL dataset profiled under both the glucose and ethanol conditions, we identified a total of 225 and 224 modules, with each module consisting of two genes and two eQTLs where the two eQTLs epistatically regulate the co-expression patterns of the two genes. We found that many of these modules have biological interpretations. Under the glucose condition, ribosome biogenesis was co-regulated with the signaling and carbohydrate catabolic processes, whereas silencing and aging related genes were co-regulated under the ethanol condition with the eQTLs containing genes involved in oxidative stress response process.     

Temporal Patterns of Apparent Leg Band Retention in North American Geese

ABSTRACT An important assumption of mark—recapture studies is that individuals retain their marks, which has not been assessed for goose reward bands. We estimated aluminum leg band retention probabilities and modeled how band retention varied with band type (standard vs. reward band), band age (1–40 months), and goose characteristics (species and size class) for Canada (Branta canadensis), cackling (Branta hutchinsii), snow (Chen caerulescens), and Ross's (Chen rossii) geese that field coordinators double-leg banded during a North American goose reward band study (N = 40,999 individuals from 15 populations). We conditioned all models in this analysis on geese that were encountered with ≥1 leg band still attached (n = 5,747 dead recoveries and live recaptures). Retention probabilities for standard aluminum leg bands were high ( = 0.9995, SE < 0.001) and constant over 1–40 months. In contrast, apparent retention probabilities for reward bands demonstrated an interactive relationship between 5 size and species classes (small cackling, medium Canada, large Canada, snow, and Ross's geese). In addition, apparent retention probabilities for each of the 5 classes varied quadratically with time, being lower immediately after banding and at older age classes. The differential retention probabilities among band type (reward vs. standard) that we observed suggests that 1) models estimating reporting probability should incorporate differential band loss if it is nontrivial, 2) goose managers should consider the costs and benefits of double-banding geese on an operational basis, and 3) the United States Geological Survey Bird Banding Lab should modify protocols for receiving recovery data.     

Oxytocin Shapes Spontaneous Activity Patterns in the Developing Visual Cortex by Activating Somatostatin Interneurons

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Visual Acceleration Perception for Simple and Complex Motion Patterns

Humans are able to judge whether a target is accelerating in many viewing contexts, but it is an open question how the motion pattern per se affects visual acceleration perception. We measured acceleration and deceleration detection using patterns of random dots with horizontal (simpler) or radial motion (more visually complex). The results suggest that we detect acceleration better when viewing radial optic flow than horizontal translation. However, the direction within each type of pattern has no effect on performance and observers detect acceleration and deceleration similarly within each condition. We conclude that sensitivity to the presence of acceleration is generally higher for more complex patterns, regardless of the direction within each type of pattern or the sign of acceleration.     

Crown Spread Patterns for Five Deciduous Broad-leaved Woody Species: Ecological Significance of the Retention Patterns of Larger Branches

Patterns of crown spread and branch retention of two shade-intolerantspecies (Betula platyphyllaandB. maximowicziana) were comparedwith three more tolerant species (Quercus mongolica,Acer sieboldianumandMagnoliaobovata). Branching height (height of the lowest living branch)rose more rapidly with age for the twoBetulaspecies than forthe shade tolerant species. Branching heights ofA. sieboldianumandM.obovatawere similar, irrespective of tree height and age, andlarger trees tended to produce wider crowns than theBetulaspecieswhen trees of similar height were compared. In all species,the branch basal area (cross-sectional area of a branch at itsbase) and the leaf area per branch generally increased as thebranch position on a stem became lower. Therefore, retaininglarger branches contributed significantly to the support ofa larger leaf area per tree. The number of larger branches (branchbasal area >80 cm²) for bothBetulaspecies was significantlysmaller than that of the shade tolerant species. The branchretention pattern ofBetulaspecies was probably a consequenceof intolerance of the leaves to shade. The decline ofBetulaspecieswith forest succession is likely to occur through their inabilityto retain branches with a large base area in closed forests.Copyright1997 Annals of Botany Company Shade tolerance; crown spread; branch retention; branch size; broad-leaved woody species; leaf area index per tree     

Attempts to Determine the Roles of Visual and Olfactory Inputs in Initial Orientation and Homing of Pigeons over Familiar Terrain

The role of familiar visual landmarks in pigeon homing is still unsettled. If they are involved, they must be thought to be utilized in parallel with olfactory signals. In order to recognize the effectiveness of either one of the input channels separately, vision and olfaction, it is therefore necessary to interfere with both of them. Pigeons were temporarily deprived of image vision by spectacles made of translucent white paper, producing a condition called V^- as compared with the largely unimpaired condition V⁺. Access to olfactory signals was temporarily prohibited by charcoal filters before release and nasal anaesthesia upon release, resulting in condition O^- versus unimpaired smelling of natural air in O⁺. Prior to the test releases, all the participating pigeons had been made familiar with the two or four test sites (and with other sites in the area) by training flights. According to decreasing levels of initial homeward orientation and homing performance, the four combinations of treatments are to be arranged in the following order: V⁺O⁺, V⁺O^-, V^-O⁺, V^-O^-. In the last type, no trace of initial homeward orientation remained, indicating that at least one of the two input channels need be functional to enable home-related orientation. Over well known terrain, either alone seems to be more or less sufficient. The results are indicative but not definitely conclusive. Effects of visual impairment on behavioural activities in general cannot clearly be separated from orientation-specific effects. Therefore, and because many pigeons refuse to fly in V^- condition or fail to provide useful data, we stopped applying this method.     

Passive Immunization of Pigeons Against Trichomoniasis

SYNOPSIS Nonimmune homing pigeons Columba livia were infected with the Jones' Barn strain of Trichomonas gallinae and subsequently transfused with plasma from acute or chronically infected pigeons harboring one of 3 different strains of T. gallinae. The transfusions were either a single 2 ml dose given one day after inoculation or three 1 ml doses given 0, 5, and 10 days after inoculation. Plasma from pigeons harboring any of the 3 strains was capable of passively immunizing nonimmune birds. All birds which were immunized with plasma from infected pigeons survived until killed at the end of the test period and no visceral lesions were found on necropsy but trichomonads were present in the oropharynx. All controls (untreated or transfused with normal plasma) died of visceral trichomoniasis.
Immune plasma produced some lysis of trichomonads in vitro, and inhibition of motility and vacuolization occurred in some of the non-lysed organisms. The overall lytic activity in vitro affected less than 10% of the suspended trichomonads.     

Large-scale Input Matching by Urban Feral Pigeons (Columba livia)

Ideal Free Distribution (IFD) theory predicts the number of animals choosing habitats of differing quality. Most experimental tests of the IFD have been conducted at small spatial scales (i.e. smaller than maximum daily movement of animals) by comparing the number of animals foraging at adjacent food patches of different quality. Urban pigeons ( Columba livia ) feed in large, open aggregations, and can distribute according to predictions of the IFD at alternative food patches. In this study, we test IFD predictions over a much larger spatial scale by comparing the abundance of urban feral pigeons at four sites spread over the city centre of Montréal, Québec, Canada, to the amount of anthropogenically provided food in each site. We found that the pigeons' distribution among the four sites qualitatively matched that of resources available at these sites. After controlling for the effect of stochastic variation in food resources, two pair-wise comparisons between sites indicated undermatching, one indicated matching and three indicated overmatching of consumers to resources. These results suggest that the pigeons inhabiting the downtown area of Montréal may behave as a single population that distributes qualitatively among foraging sites in proportion to the quantity of food offered, and that deviations from expectations cannot be attributed simply to stochastic variation in the food levels at the sites.     

Salt Retention by Bean Hypocotyl

The ultrastructure of hypocotyl, epicotyl, and petiole of bean(Phaseolus vulgaris, L.) was investigated in plants grown ina basic solution in the absence or presence of high levels ofchloride salts. The hypocotyl tissue of both control and salt-treatedplants showed frequent vesiculation similar to that previouslyobserved in the root and hypocotyl of the halophyte, Salicorniaeuropea, L. These vesicles were not previously observed in theroot and leaf of bean plants that were grown under identicalconditions in the absence of high levels of chloride salt. Experiments concerning the localization of chloride as electron-densesilver-complex showed that the vesicles contain a chloride concentrationas high as the cytoplasmic phase or the free space. These resultsare discussed in relation to the ionic retention property ofthe bean hypecotyl and the role of vesiculation in salt resistanceof plants.     

Foreign Organelle Retention by Ciliates

SYNOPSIS. Intact algal chloroplasts were found by electron microscopy in the peripheral cytoplasm of 2 ecologically important species of planktonic marine ciliates. The exact origin of the chloroplast is uncertain and the periods of their retention by the protozoa is unknown. The 2 ciliate species may function partially or fully as primary producers. In other ciliates algal eye-spots are retained and may actually be utilized. Ecologic and evolutionary implications of the observations are discussed.