Behavior of filamentous cyanobacteria in laboratory culture

The observations of a laboratory culture of filamentous cyanobacteria revealed a complex of behavioral responses of their community, which maintain their activity as an integrated entity. A number of structures formed in the course of filament regrouping were revealed and described; their possible structural and functional analogues in eukaryotic organisms were determined. It is assumed that the behavioral reactions of the filaments help to maintain the integrity of the community at the stage prior to the formation of the structural bonds between its elements.     

The maintenance of structural integrity in freshwater protozoan communities under stress

The structural assimilative capacity (ability to maintain biological integrity under stress) of protozoan communities from nine lakes in the area of the University of Michigan Biological Station, Pellston, Michigan, and six stations at Smith Mountain Lake, Virginia, were studied (1) to determine if communities from lakes of differing trophic state differ in their ability to assimilate various amounts of copper sulfate, and (2) to explore the possible influence of average density of individuals and/or qualitative differences in the types of species present on any observed differences in assimilative capacity.In both the northern Michigan and Smith Mountain Lake studies, a trend in response was demonstrated along the eutrophic-oligotrophic gradient; eutrophic communities had a greater structural assimilative capacity than did oligotrophic communities. Both mean species density and community composition appear to be important factors in the ability to maintain structural integrity.     

退化植物群落结构及其物种组成在人为干扰梯度上的响应

在岷江上游大沟流域,沿着人为干扰梯度,调查了退化榛栎群落的结构及其物种组成变化。结果表明：（１）除密度外,群落木本层的结构特性（密度、高度、生物量、基径面积和物种多样性）与干扰强度的增加呈负相关,而其草本物种多样性、生态优势度呈正反应,但地上生物量变化呈现相反的趋势;（２）根据群落内植物种群密度（或盖度）在干扰梯度上的响应变化,群人４７个种可基本上分成３个反应种组：１６个为扩展种（ｉｎｖａｓｉｖｅ     

Effect of landscape configuration and habitat quality on the community structure of waterbirds using a man-made habitat

Species occurrence and community structure are strongly influenced by multiple factors like habitat selection, species movement capabilities, competition, or conspecific and heterospecific attractions. More specifically, in waterbird communities, previous studies have identified the importance of environmental and structural characteristics of wetlands for their occupation and use. However, the effect of the surrounding landscape configuration remains unknown. In this article, we use a large network of artificial irrigation ponds to evaluate the importance of pond features in comparison to the effect of landscape and spatial configuration on the community at three different spatial scales. Our results show that landscape configuration has relatively little influence on structure of the waterbird community. Pond features were by far the most important variables to describe waterbird abundance and richness. At the species level, we detected differences in habitat preferences relating to species-specific ecological requirements. Our results highlight the importance of using a multiscale approach to understand and predict richness and abundance in waterbird communities. Our findings emphasize the need to maintain high-quality ponds to enhance their suitability for use as breeding and foraging sites.     

Predator and Prey Models with Flexible Individual Behavior and Imperfect Information

To begin identifying what behavioral details might be needed to characterize community dynamics and stability, we examined the effect of prey behavioral responses to predation risk on community dynamics and stability. We considered the case of prey altering their foraging effort to trade off energy gain and predation risk. We used state-dependent dynamic optimization to calculate the optimal trade-off for four models of prey behaviorally responding to predation risk. We consider a fixed behavior model in which prey use constant levels of foraging effort and three flexible behavior models in which prey change their foraging effort according to their physiological state and their perceived level of predation risk. Flexible behavior was destabilizing at the community level as evidenced by higher predator-prey oscillations and lower community persistence times. The mechanisms by which prey estimated predation risk also affected community stability. We found that community dynamics resulting from prey with flexible behavior and fixed perception of risk approximated community dynamics resulting from prey with flexible behavior and perfect information about predation risk, however neither approximated the community dynamics resulting from prey with flexible behavior and flexible perception of risk. Thus, whether it might be possible to abstract complex behavior with simpler rules when modeling community dynamics depends on the prey's behavioral mechanisms, which are empirically poorly known.     

Selected Neurophysiological,Psychological, and Behavioral Influences on Subjective Sleep Quality in Nurses: A Structure Equation Model

Few studies have examined relationships among neurophysiological, psychological, and behavioral factors with regard to their effects on sleep quality. We used a structure equation model to investigate behavioral and psychological factors that influence neurophysiological regulation of sleep in shift workers. Using a cross-sectional study design, we tested the model with a sample of 338 female nurses working rotating shifts at an urban regional hospital. The Morningness-Eveningness Questionnaire (MEQ) and short-form Menstrual Distress Questionnaire (MDQ) were used to measure neurophysiological factors involved in morningness-eveningness and menstrual distress. The Sleep Hygiene Awareness and Practice Scale (SHAPS) and Profile of Mood States Short Form (POMS-SF) were completed to measure behavioral factors of sleep hygiene practices and psychological factors of mood states. In addition, the Pittsburgh Sleep Quality Index (PSQI) measured participant''s self-reported sleep quality. The results revealed that sleep hygiene practices and mood states mediated the effects of morningness-eveningness and menstrual distress on sleep quality. Our findings provide support for developing interventions to enhance sleep hygiene and maintain positive mood states to reduce the influence of neurophysiological factors on sleep quality among shift workers.     

De novo tubular nanostructure design based on self-assembly of beta-helical protein motifs

We present an approach for designing self-assembled nanostructures from naturally occurring building block segments obtained from native protein structures. We focus on structural motifs from left-handed beta-helical proteins. We selected 17 motifs. Copies of each of the motifs are stacked one atop the other. The obtained structures were simulated for long periods by using Molecular Dynamics to test their ability to retain their organization over time. We observed that a structural model based on the self-assembly of a motif from E. coli galactoside acetyltransferase produced a very stable tube. We studied the interactions that help maintain the conformational stability of the systems, focusing on the role of specific amino acids at specific positions. Analysis of these systems and a mutational study of selected candidates revealed that the presence of proline and glycine residues in the loops of beta-helical structures greatly enhances the structural stability of the systems.     

Consequences of load carrying by birds during short flights are found to be behavioral and not energetic

The doubly-labeled water technique and video were used to measure the effect of mass loading on energy expenditure and takeoff performance in zebra finches, Taeniopygia guttata, that were making routine (nonalarm) short flights. Finches that carried 27% additional mass did not expend more energy during flight than unloaded controls. Carrying additional mass, however, led to a reduced body mass and a decreased velocity during takeoffs (by 12%). Calculations of instantaneous mechanical power indicated that energy expended by unloaded and loaded finches at takeoff was similar, due to the observed decrease in velocity by mass-loaded finches and a lowering of their body mass. During routine short flights, zebra finches appear to maintain their metabolic power input and mechanical power output regardless of mass loading. Here, the costs of carrying additional mass during routine short flights were revealed to be behavioral and not energetic.     

Demographic influences on the behavior of chimpanzees

Recent research has revealed substantial diversity in the behavior of wild chimpanzees. Understanding the sources of this variation has become a central focus of investigation. While genetic, ecological, and cultural factors are often invoked to explain behavioral variation in chimpanzees, the demographic context is sometimes overlooked as a contributing factor. Observations of chimpanzees at Ngogo, Kibale National Park, Uganda, reveal that the size and structure of the unit group or community can both facilitate and constrain the manifestation of behavior. With approximately 150 individuals, the Ngogo community is much larger than others that have been studied in the wild. We have taken advantage of the unusual demographic structure of this community to document new and intriguing patterns of chimpanzee behavior with respect to hunting, territoriality, and male social relationships. Chimpanzees at Ngogo hunt often and with a considerable degree of success. In addition, male chimpanzees there frequently patrol the boundary of their territory and engage in repeated bouts of lethal intergroup aggression. By forming two distinct subgroups, male chimpanzees at Ngogo also develop social bonds above the level of dyadic pairs. While the sheer number of chimpanzees contributes to differences in hunting, patrolling, mating, and subgrouping at Ngogo, the demographic situation may also constrain behavioral interactions. At Ngogo, male chimpanzees who are closely related genetically through the maternal line do not appear to affiliate or cooperate with each other. Demographic constraints may be responsible for this finding. In this paper, I use these examples to illustrate how the demographic context affects the possible range of behavioral options open to individuals and ultimately contributes to the explanation of behavioral diversity in chimpanzees.     

Association of isolated bovine kidney cortex peroxisomes with endoplasmic reticulum

Close lateral membrane associations of peroxisomes with endoplasmic reticulum are a common feature in bovine kidney cortex epithelial cells. Isolated highly purified peroxisome preparations from this tissue showed a remarkable and persistent copurification of peroxisomal marker enzymes with small amounts (5%) of the microsomal reference enzymes esterase and glucose-6-phosphatase. Contamination with mitochondrial and lysosomal markers was negligible. Ultrastructural examination of such preparations revealed a peculiar association of vesicles or short tubular segments with the peroxisomal membrane. Short electron dense crossbridges seemed to maintain their structural association. The cytochemical localization of glucose-6-phosphatase in peroxisome-associated membrane structures confirmed their derivation from endoplasmic reticulum. The metabolic significance of such structural peroxisome-endoplasmic reticulum associations is discussed.     

Serous cutaneous glands of the Pacific tree-frog Hyla regilla (Anura, Hylidae): patterns of secretory release induced by nor-epinephrine

The serous (poison) cutaneous glands of the Pacific tree-frog Hyla regilla were induced to release their product by 10(-3)M nor-epinephrine stimulation. After discharge structural and ultrastructural features of the cutaneous glands involved in release were observed. Furthermore, the discharged product, consisting of discrete, secretory granules, was collected and processed for transmission electron microscope analysis. As indicated by patterns found in the myoepithelium encircling the syncytial secretory unit, gland discharge is caused by contraction of the peripheral myocytes. Muscle cell compression dramatically affects the syncytium and results in degenerative changes, including expulsion of the secretory unit nuclei. Therefore, the structural collapse in depleted glands has been ascribed to the mechanical activity performed by the myoepithelium during discharge, rather than cytoplasm involution described in conventional, holocrine glands. TEM investigation revealed that the secretory granules collected after discharge maintain their peculiar traits: they consist of recurrent patterns of thin subunits, acquired during serous maturation and provided with remarkable structural stability.     

Structure,dynamics and dendroecology of an old‐growth Fagus forest in the Apennines

Abstract. Question: Which are the structural attributes and the history of old‐growth Fagus forest in Mediterranean montane environments? What are the processes underlying their structural organization? Are these forests stable in time and how does spatial scale affect our assessment of stability? How do these forests compare to other temperate deciduous old‐growth forests? Location: 1600–1850 m a.s.l., Fagus forest near the tree line, central Apennines, Italy. Methods: An old‐growth Fagus forest was studied following historical, structural and dendroecological approaches. History of forest cover changes was analysed using aerial photographs taken in 1945, 1954, 1985 and 1994. The structural analysis was carried out in the primary old‐growth portion of the forest using 18 circular and two rectangular plots. Dendroecological analyses were conducted on 32 dominant or co‐dominant trees. Results: These primary old‐growth Fagus remnants consist of four patches that escaped logging after World War II. Both living and dead tree components are within the range of structural attributes recognized for old‐growth in temperate biomes. Dendroecological analyses revealed the roles of disturbance, competition and climate in structuring the forest. We also identified a persistent Fagus community in which gap‐phase regeneration has led to a mono‐specific multi‐aged stand at spatial scales of a few hectares, characterized by a rotated‐sigmoid diameter distribution. Conclusion: Even at the relatively small spatial scale of this study, high‐elevation Apennine Fagus forests can maintain structural characteristics consistent with those of old‐growth temperate forests. These results are important for managing old‐growth forests in the Mediterranean montane biome.     

The overlapping community structure of structural brain network in young healthy individuals

Community structure is a universal and significant feature of many complex networks in biology, society, and economics. Community structure has also been revealed in human brain structural and functional networks in previous studies. However, communities overlap and share many edges and nodes. Uncovering the overlapping community structure of complex networks remains largely unknown in human brain networks. Here, using regional gray matter volume, we investigated the structural brain network among 90 brain regions (according to a predefined anatomical atlas) in 462 young, healthy individuals. Overlapped nodes between communities were defined by assuming that nodes (brain regions) can belong to more than one community. We demonstrated that 90 brain regions were organized into 5 overlapping communities associated with several well-known brain systems, such as the auditory/language, visuospatial, emotion, decision-making, social, control of action, memory/learning, and visual systems. The overlapped nodes were mostly involved in an inferior-posterior pattern and were primarily related to auditory and visual perception. The overlapped nodes were mainly attributed to brain regions with higher node degrees and nodal efficiency and played a pivotal role in the flow of information through the structural brain network. Our results revealed fuzzy boundaries between communities by identifying overlapped nodes and provided new insights into the understanding of the relationship between the structure and function of the human brain. This study provides the first report of the overlapping community structure of the structural network of the human brain.     

How ecosystems adapt to face disruptive impact? The case of a commercial harbor benthic community

Commercial harbors are commonly considered as definitively lost environment sacrificed in the name of economic development, but, recently, a growing attention has been addressed to harbor ecology and harbor ecological state. The objective of this research is to identify the adaptation strategy carried out by the benthic community of Voltri harbor (NW Italy) by means of the application of a set of whole system metrics. Thermodynamic and network analysis revealed harbor benthic community characterized by an efficient and active network but also scarcely able to maintain complex structures and organisms. These results can be interpreted as evidences of adaptations carried out by the harbor benthic community that revealed itself healthy even if poorly resilient and thus not able to face further disturbances.     

Ordination of breeding birds in relation to environmental gradients in three southeastern United States floodplain forests

We used an ordination approach to identify factors important to the organization of breeding bird communities in three floodplains: Cache River, Arkansas (AR), Iatt Creek, Louisiana (LA), and the Coosawhatchie River, South Carolina (SC), USA. We used 5-min point counts to sample birds in each study area each spring from 1995 to 1998, and measured ground-surface elevations and a suite of other habitat variables to investigate bird distributions and community characteristics in relation to important environmental gradients. In both AR and SC, the average number of Neotropical migrant species detected was lowest in semipermanently flooded Nyssa aquatica Linnaeus habitats and greatest in the highest elevation floodplain zone. Melanerpes carolinus Linnaeus, Protonotaria citrea Boddaert, Quiscalus quiscula Linnaeus, and other species were more abundant in N. aquatica habitats, whereas Wilsonia citrina Boddaert, Oporornis formosus Wilson, Vireo griseus Boddaert, and others were more abundant in drier floodplain zones. In LA, there were no significant differences in community metrics or bird species abundances among forest types. Canonical correspondence analyses revealed that structural development of understory vegetation was the most important factor affecting bird distributions in all three study areas; however, potential causes of these structural gradients differed. In AR and SC, differences in habitat structure were related to the hydrologic gradient, as indexed by ground-surface elevation. In LA, structural variations were related mainly to the frequency of canopy gaps. Thus, bird communities in all three areas appeared to be organized primarily in response to repeated localized disturbance. Our results suggest that regular disturbance due to flooding plays an important role in structuring breeding bird communities in floodplains subject to prolonged inundation, whereas other agents of disturbance (e.g., canopy gaps) may be more important in headwater systems subject to only short-duration flooding. Management for avian community integrity in these systems should strive to maintain forest zonation and natural disturbance regimes.     

内蒙古羊草草原17年刈割演替过程中功能群组成动态及其对群落净初级生产力稳定性的影响

基于17 yr的野外实验数据,研究了内蒙古羊草草原群落刈割演替过程中的功能群组成动态,探索了功能群组成变化与群落净初级生产力(ANPP)之间的关系,分析了结构参数怎样影响功能参数.结果显示:在17 yr的割草演替过程中,群落的结构与功能均发生了变化.随着羊草群落刈割演替的进行,群落的功能群组成发生了显著变化,根茎禾草在群落中的优势地位相继被一、二年生植物、高丛生禾草和矮丛生禾草所取代.到17 yr末,群落变成根茎禾草、矮丛生禾草、高丛生禾草共同建群的群落.在对照群落中ANPP与年降水量显著相关,但在刈割群落中二者则不相关.年降水量解释对照群落ANPP变异的62%,而连年的刈割干扰则是刈割群落中ANPP动态的主要驱动因子.群落净初级生产则显出对刈割干扰的抵抗能力,在刈割干扰的前几年,依靠群落内功能群组成的不断调节,保持相对稳定的水平,当刈割进行5 yr之后,群落结构的变化积累到一定程度,净初级生产迅速下降到一个较低的水平,此后依靠群落结构的不断调节来维持这一功能水平.因此,群落结构是以渐变的方式改变的,而群落功能的下降则是以跃变的形式完成的.群落依赖于结构的不断调整来保持功能的相对稳定,但结构变化到一定程度也会导致功能的衰退.     

内蒙古羊草草原17年刈割演替过程中功能群组成动态及其对群落净初级生产力稳定性的影响(英文)

基于17 yr的野外实验数据,研究了内蒙古羊草草原群落刈割演替过程中的功能群组成动态,探索了功能群组成变化与群落净初级生产力(ANPP)之间的关系,分析了结构参数怎样影响功能参数。结果显示:在17 yr的割草演替过程中,群落的结构与功能均发生了变化。随着羊草群落刈割演替的进行,群落的功能群组成发生了显著变化,根茎禾草在群落中的优势地位相继被一、二年生植物、高丛生禾草和矮丛生禾草所取代。到17 yr末,群落变成根茎禾草、矮丛生禾草、高丛生禾草共同建群的群落。在对照群落中ANPP与年降水量显著相关,但在刈割群落中二者则不相关。年降水量解释对照群落ANPP变异的62％,而连年的刈割干扰则是刈割群落中ANPP动态的主要驱动因子。群落净初级生产则显出对刈割干扰的抵抗能力,在刈割干扰的前几年,依靠群落内功能群组成的不断调节,保持相对稳定的水平,当刈割进行5 yr之后,群落结构的变化积累到一定程度,净初级生产迅速下降到一个较低的水平,此后依靠群落结构的不断调节来维持这一功能水平。因此,群落结构是以渐变的方式改变的,而群落功能的下降则是以跃变的形式完成的。群落依赖于结构的不断调整来保持功能的相对稳定,但结构变化到一定程度也会导致功能的衰退。     

Scanning electron microscopy of the subarachnoid space in the dog: evidence for a non-hematogenous origin of subarachnoid macrophages.

Injection of viable BCG into the subarachnoid space of immunized and non-immunized dogs produced a 10-fold increase in the populations of pial free cells. In immunized animals injected three days previously with BCG, stereoscopic SEM revealed that many pial cells had rounded up and were protruding into the subarachnoid space. With continued rounding these cells took on amoeboid characteristics, with shapes that suggested a capacity for cell movement. Internally, these pial cells possessed an increased volume of perinuclear cytoplasm and organelles. Reactive pial cells could be distinguished from macrophages of presumed hematogenous origin on the basis of their surface morphology. These findings suggested that pial cells had the ability to alter their normal structural and behavioral characteristics and to become macrophage-like under these conditions of secondary challenge by BCG.     

Multimodal pair-bond maintenance: A review of signaling across modalities in pair-bonded nonhuman primates

Only a handful of primate species exhibit the social relationship of pair-bonding. Efficient communication is critical for behavioral coordination within pair-bonds to maintain proximity and respond appropriately to extra-pair individuals, and possibly coordinate infant care. The use of complex signaling across modalities may help individuals improve communicative outcomes. We review many ways that pair-bonded species use signals to communicate and maintain bonds, though little previous research has taken a truly multimodal approach within a single species. We make a call for further investigation into pair-bonded communication using a multimodal approach to better understand how these species use all their senses to build, maintain, and advertise their bonds.     

A Critical Interpersonal Distance Switches between Two Coordination Modes in Kendo Matches

In many competitive sports, players need to quickly and continuously execute movements that co-adapt to various movements executed by their opponents and physical objects. In a martial art such as kendo, players must be able to skillfully change interpersonal distance in order to win. However, very little information about the task and expertise properties of the maneuvers affecting interpersonal distance is available. This study investigated behavioral dynamics underlying opponent tasks by analyzing changes in interpersonal distance made by expert players in kendo matches. Analysis of preferred interpersonal distances indicated that players tended to step toward and away from their opponents based on two distances. The most preferred distance enabled the players to execute both striking and defensive movements immediately. The relative phase analysis of the velocities at which players executed steps toward and away revealed that players developed anti-phase synchronizations at near distances to maintain safe distances from their opponents. Alternatively, players shifted to in-phase synchronization to approach their opponents from far distances. This abrupt phase-transition phenomenon constitutes a characteristic bifurcation dynamics that regularly and instantaneously occurs between in- and anti-phase synchronizations at a critical interpersonal distance. These dynamics are profoundly affected by the task constraints of kendo and the physical constraints of the players. Thus, the current study identifies the clear behavioral dynamics that emerge in a sport setting.