Divergence in behavioural responses to stress in two strains of rainbow trout (Oncorhynchus mykiss) with contrasting stress responsiveness

The aim of this study was to establish whether two lines of rainbow trout divergent for their plasma cortisol response to a standardized stressor would show consistent differences in their behavioural response to a range of challenging situations. Our results show that the high- and low-responding (HR and LR) lines of rainbow trout did not differ in the aggression shown towards an intruder or in their response to the introduction of a novel object to their home environment. However, there was a difference in behaviour between the two selection lines when they were exposed to two unfamiliar environments. These results suggest that the behaviour of the HR and LR fish differs when they are challenged in unfamiliar environments, while their behaviour does not differ when they are challenged in their home environment. These observations are in agreement with studies on mammals that show that individuals with reactive coping styles perform similarly to proactive animals when they are challenged in a familiar environment, while they show different behaviour when they are challenged in unfamiliar environments. Thus, these results provide further evidence that the HR and LR selection lines of rainbow trout exemplify the two different coping styles described in mammals.     

The case for studying tadpole autecology,with comments on strategies to study other small,fast-moving animals in nature

Two of the most fundamental questions in tadpole biology, also applicable to most small, under-studied organisms are: (1) ‘Why are they built the way they are?’ and (2) ‘Why do they live where they do?’ Regrettably, despite significant progress in most aspects of tadpole biology, the answers to these questions are not much better now than they were in the last century. We propose that an autecological approach, that is the careful observation of individuals and how they interact with the environment, is a potential path towards a fuller understanding of tadpole ecomorphology and evolution. We also discuss why more attention should be given to studying atypical tadpoles from atypical environments, such as torrential streams, water-filled cavities of terrestrial plants and wet rock surfaces neighbouring streams. Granted, tadpoles are rare in these settings, but in those unusual habitats the physical environments can be well described and characterized. In contrast, the more common ponds where tadpoles are found are typically too structurally complex to be easily delineated. This makes it difficult to know exactly what individual tadpoles are doing and what environmental parameters they are responding to. Our overall thesis is that to understand tadpoles we must see exactly what they are doing, where they are doing it, and how they are doing it. This takes work, but we suggest it is feasible and could greatly advance our understanding of how anuran larvae have evolved. The same strategies for studying tadpoles that we encourage here can be applied to the study of many other small and fast-moving animals.     

A mathematical model for vasogenic brain edema

Animals reproducing sexually are faced with a dilemma. They can mate in the local area where they were born, but must then take the risk that they will mate with a close relative and produce offspring suffering from inbreeding depression. Or they can migrate to a new area and mate with an unrelated animal, but then there is a chance that they will die or lose valuable reproductive time during the migration.This dilemma is here described by some simple models. The condition for spreading of a new reproductive strategy in a population is given. The results are discussed using data from the Great Tit, Man and the Japanese Quail on the effect of inbreeding.     

Joint Confidence Sets in Multiple Dilution Assays

Let {Q₁, …, Q_k} be the potencies of k substances relative to a standard in a multiple dilution assay. Joint confidence bounds for these are given with confidence coefficient at least 1-α. These bounds are easily interpreted; they appeal to available tables; they improve Scheffe's bounds; they are based on applicable probability inequalities together with extensions of Fieller's theorem; and they are genuinely nonparametric. The procedures are illustrated using data from parallel-line and slope-ratio assays.     

Horned lizards (Phrynosoma) incapacitate dangerous ant prey with mucus

Horned lizards (Iguanidae, Phrynosomatinae, Phrynosoma) are morphologically specialized reptiles characterized by squat, tank-like bodies, short limbs, blunt snouts, spines and cranial horns, among other traits. They are unusual among lizards in the degree to which they specialize on a diet of ants, but exceptional in the number of pugnacious, highly venomous, stinging ants they consume, especially harvester ants (genus Pogonomyrmex). Like other iguanian lizards, they capture insect prey on the tongue, but unlike other lizards, they neither bite nor chew dangerous prey before swallowing. Instead, they employ a unique kinematic pattern in which prey capture, transport and swallowing are combined into a single feeding stage, apparently leaving the mouth, pharynx, esophagus and stomach vulnerable to bites and stings. Nevertheless, horned lizards consume dozens of harvester ants without harm. We show that their derived feeding kinematics are associated with unique, mucus-secreting pharyngeal papillae that apparently serve to immobilize and incapacitate dangerous ants as they are swallowed by compacting them and binding them in mucus strands. Radially branched esophageal folds provide additional mucus-secreting surfaces the ants pass through as they are swallowed. Ants extracted from fresh-killed horned lizard stomachs are curled ventrally into balls and bound in mucus. We conclude that the pharyngeal papillae, in association with a unique form of hyolingual prey transport and swallowing, are horned lizard adaptations related to a diet of dangerous prey. Harvester ant defensive weapons, along with horned lizard adaptations against such weapons, suggest a long-term, predator-prey, co-evolutionary arms race between Phrynosoma and Pogonomyrmex. J. Exp. Zool. 309A:447-459, 2008. (c) 2008 Wiley-Liss, Inc.     

Risk-Sensitivity in Bayesian Sensorimotor Integration

Information processing in the nervous system during sensorimotor tasks with inherent uncertainty has been shown to be consistent with Bayesian integration. Bayes optimal decision-makers are, however, risk-neutral in the sense that they weigh all possibilities based on prior expectation and sensory evidence when they choose the action with highest expected value. In contrast, risk-sensitive decision-makers are sensitive to model uncertainty and bias their decision-making processes when they do inference over unobserved variables. In particular, they allow deviations from their probabilistic model in cases where this model makes imprecise predictions. Here we test for risk-sensitivity in a sensorimotor integration task where subjects exhibit Bayesian information integration when they infer the position of a target from noisy sensory feedback. When introducing a cost associated with subjects'' response, we found that subjects exhibited a characteristic bias towards low cost responses when their uncertainty was high. This result is in accordance with risk-sensitive decision-making processes that allow for deviations from Bayes optimal decision-making in the face of uncertainty. Our results suggest that both Bayesian integration and risk-sensitivity are important factors to understand sensorimotor integration in a quantitative fashion.     

The architecture of the accessory reproductive glands of the male desert locust 2: Microtubular structures

Cytoplasmic microtubules are distributed widely in the mature accessory reproductive glands of the male desert locust. They are not concentrated in any particular region of the cytoplasm, but they appear to be closely associated with mitochondria and the Golgi apparatus. The individual microtubules have a helical configuration, and they are often congregated in bundles. It is suggested that the microtubules arise from Golgi regions, and that they function as a scaffolding for the maintenance of the shape of the glandular cells.     

Measurement of the susceptibility of paramagnetically labeled cells with paramagnetic solutions

A method of measuring the volumetric magnetic susceptibility, in which magnetically labeled cells or other particles are suspended in a paramagnetic solution of known susceptibility over the poles of a magnet, is presented. If the cells are more magnetic than the solution, they are attracted toward the poles; if they are less magnetic, they are repelled. If they have the same susceptibility as the solution, they do not move. Under this condition, the cells are said to be "isomagnetic" with the surrounding solution. Since the volumetric susceptibility of this solution is known, the susceptibility of the cells is obtained. Using the "isomagnetic" method, the volumetric susceptibilities of test metal powders were determined within +/- 8 X 10(-6) SI units. Yeast, colonic carcinoma, and liver cells, rendered magnetic with erbium chloride, had susceptibilities ranging from 13 to 20 X 10(-6). Particles of articular cartilage treated with erbium chloride were heterogeneous, with susceptibilities ranging between 50 and 125 X 10(-6), while particles of bone had a susceptibility of 560 to 580 X 10(-6). Eukaryotic cells labeled with ferritin attained susceptibilities of less than 1 X 10(-6).     

Five-Year Olds,but Not Chimpanzees,Attempt to Manage Their Reputations

Virtually all theories of the evolution of cooperation require that cooperators find ways to interact with one another selectively, to the exclusion of cheaters. This means that individuals must make reputational judgments about others as cooperators, based on either direct or indirect evidence. Humans, and possibly other species, add another component to the process: they know that they are being judged by others, and so they adjust their behavior in order to affect those judgments – so-called impression management. Here, we show for the first time that already preschool children engage in such behavior. In an experimental study, 5-year-old human children share more and steal less when they are being watched by a peer than when they are alone. In contrast, chimpanzees behave the same whether they are being watched by a groupmate or not. This species difference suggests that humans'' concern for their own self-reputation, and their tendency to manage the impression they are making on others, may be unique to humans among primates.     

Cold shock response and low temperature adaptation in psychrotrophic bacteria

Psychrotrophic bacteria are capable of developing over a wide temperature range and they can grow at temperatures close to or below freezing. This ability requires specific adaptative strategies in order to maintain membrane fluidity, the continuance of their metabolic activities, and protein synthesis at low temperature. A cold-shock response has been described in several psychrotrophic bacteria, which is somewhat different from that in mesophilic microorganisms: (i) the synthesis of housekeeping proteins is not repressed following temperature downshift and they are similarly expressed at optimal and low temperatures (ii) cold-shock proteins or Csps are synthesized, the number of which increases with the severity of the shock (iii) a second group of cold-induced proteins, i.e. the cold acclimation proteins or Caps, comparable with Csps are continuously synthesized during prolonged growth at low temperature. Homologues to CspA, the major cold-shock protein in E. coli, have been described in various psychrotrophs, but unlike their mesophilic counterparts, they belong to the group of Caps. Although they have been poorly studied, Caps are of particular importance since they differentiate psychrotrophs from mesophiles, and they are probably one of the key determinant that allow life at very low temperature.     

Subviral pathogens of plants: viroids and viroidlike satellite RNAs.

Contrary to earlier beliefs, viruses are not the smallest causative agents of infectious diseases. Single-stranded RNAs as small as 246 nucleotides exist in certain higher plants and cause more than a dozen crop diseases. These RNAs have been termed viroids. Despite their extremely limited information content, viroids replicate autonomously in susceptible cells--that is, they do not require helper functions from simultaneously replicating conventional viruses. Viroids are covalently closed circular molecules with a characteristic rodlike secondary structure in which short helical regions are interrupted by internal and bulge loops. Viroids are not translated; they are replicated by a host enzyme (or enzymes) (probably RNA polymerase II) via oligomeric RNA intermediates by a rolling circle mechanism. Viroidlike satellite RNAs resemble viroids in size and molecular structure, but are found within the capsids of specific helper viruses on which they depend for their own replication. These RNAs are of great interest to molecular biology for at least two reasons: 1) they are the smallest and simplest replicating molecules known, and 2) they may represent living fossils of precellular evolution in a hypothetical RNA world.     

Cultural Identity and Illness: Fulani Views

Cultural identity – who the Fulani think they are – informs thinking onillnesses they suffer. Conversely, illness, so very prevalent insub-Saharan Africa, provides Fulani with a constant reminder of theirdistinctive condition in Guinea. How they approach being ill also tellsFulani about themselves. The manner in which Fulani think they are sickexpresses their sense of difference from other ethnic groups. Schemas ofillness and of collective identity draw deeply from the same well andweb of thoughts. Three different approaches of schema theory are used totrace what ties illness to identity. These are 1) the schema asprototype; 2) a connectionist approach associates schemas for illnesswith other cultural schemas; and 3) a hierarchy of schemas. Thehierarchy includes master schemas for ethnic identity, schemas forillness generally and sub-schemas for separate ailments. Schemas orientand provide a framework for the practice of being Fulani – in the sensethat Bourdieu would describe practice as the application of practicalknowledge. Illnesses above the waist are said to be part of the Fulanicondition of belonging in arid climates while they need suffer thehumidity of Guinea. Illnesses below the waist are thought to arise whenone does not act like a Fulani, especially in matters of food and sex.As individuals disclose or conceal illness, as they discuss illness andthe problem of others they reflect standards of Fulani life – beingstrong of character not necessarily of body, being disciplined,rigorously Moslem, and leaders among lessors. To disregard standards orto suggest one does not care about such standards is shameful and placesone out of phase with others and with cultural norms. But to be in stepwith others and with cultural norms is to have pride in the self and thefoundations of Fulani life.     

Pollination failure in plants: why it happens and when it matters

Pollination is the primary step in seed formation. Pollination biologists have shown that pollination failure can occur at all steps in the dispersal process and at several different levels. Increased risk of pollination failure is associated with pollen if it is delivered to a stigma too little, too much, too late, too mixed in composition or too poor in quality. It is associated with pollinators when they are too few or too inconstant, and with plants when they are too specialized or too selective. It is associated with populations when they are too sparse, too small in number or too uniform genetically, and with communities when they are too fragmented, genetically impoverished or under rapid modification. Understanding the causes of pollination failure in plants can aid the successful conservation and recovery of rare plants, maintenance of crop yields, and sustainable use of wild plant resources such as forest timber.     

Nest-site selection in the great golden digger wasp, Sphex ichneumoneus L. (Sphecidae)

Abstract. 1. Sphex ichneumoneus are solitary, ground-nesting wasps with apparently broad nesting requirements.
2. Nest-site selecting behaviour involves four levels of decisions. First, the wasps are not active unless temperatures are high and they are less active during cloudy weather. Second, at the beginning of a nesting sequence they generally fly to the site from which they emerged, but occasionally they fly to other flat, vegetation-free areas. Third, after landing, they engage in a predigging search of the area, walking around, looking into and briefly digging in the nests of other wasps. In this way they apparently compare and choose to begin digging in the warmest areas available which are not too close to other nests. Fourth, if the soil is too soft and collapses or if it is too hard-packed, the wasp resumes the predigging search. The preference for digging within a range of compactness means that they generally choose sandy loam.
3. Theory would suggest that the wasps may spend an optimal amount of time in the predigging search behaviour and that frequency-dependent selection may be an important factor in the choice of nesting sites.
4. By choosing nesting sites according to these rules, the wasps are ensuring that their offspring develop in the warmest and best-drained soils available.     

Na channels and two types of Ca channels in rat pancreatic B cells identified with the reverse hemolytic plaque assay

The reverse hemolytic plaque assay (RHPA) was used to study the secretory properties of single rat pancreatic B cells, and to identify insulin-secreting cells for patch-clamp experiments. In secretion studies using the RHPA, we find that the percentage of secreting B cells and the amount of insulin secreted per B cell increase as the glucose concentration is raised from 0 to 20 mM. Using the whole-cell variation of the patch-clamp technique, we find that identified B cells have three types of channels capable of carrying inward current: (a) tetrodotoxin-sensitive, voltage-dependent Na channels, which are nearly completely inactivated at -40 mV, (b) fast deactivating (FD) Ca channels, and (c) slowly deactivating (SD) Ca channels. We have shown that Na channels are functionally significant to the B cell, because tetrodotoxin partially inhibits glucose-induced insulin secretion. The properties of FD and SD Ca channels differ in several respects. FD channels deactivate at -80 mV, with a time constant of 129 microseconds, they are half-maximally activated near +15 mV, they do not inactivate during 100 ms, they conduct Ba2+ better than Ca2+, and they are very sensitive to washout during intracellular dialysis. SD channels, on the other hand, deactivate with a time constant of 2.8 ms, they are half-maximally activated near -5 mV, they inactivate rapidly, they conduct Ba2+ and Ca2+ equally well, and they are insensitive to washout.     

Protein aggregation and its consequences for human disease

Protein molecules have emerged through evolution so that they are able to remain in their functional and soluble states under normal physiological conditions, although in other situations they often have a high propensity to aggregate. Aggregation in vivo is associated with a wide range of human disorders, including Alzheimer's disease and type II diabetes, medical conditions that are becoming increasingly common in the modern world. In such diseases, aggregated proteins can often be observed as highly intractable thread-like species known as amyloid fibrils. This article provides an overview of our present knowledge of the nature of these fibrillar aggregates and the manner in which they form, and discusses the origins and potential means of suppression of the pathogenic properties with which they and their precursors are associated.     

RNA–Chromatin Interactome: What? Where? When?

Molecular Biology - It was noticed in the early 1960s that a large amount of RNAs is associated with chromatin. What kind of RNAs are they? Where are they located on chromatin? When and in what...     

Release from Parasites as Natural Enemies: Increased Performance of a Globally Introduced Marine Crab

Introduced species often seem to perform better than conspecifics in their native range. This is apparent in the high densities they may achieve or the larger individual sizes they attain. A prominent hypothesis explaining the success of introduced terrestrial species is that they are typically free of or are less affected by the natural enemies (competitors, predators, and parasites) they encounter in their introduced range compared to their native range. To test this hypothesis in a marine system, we conducted a global assessment of the effect of parasitism and predation on the ecological performance of European green crab populations. In Europe, where the green crab is native, crab body size and biomass were negatively associated with the prevalence of parasitic castrators. When we compared native crab populations with those from introduced regions, limb loss (an estimator of predation) was not significantly lower in introduced regions, parasites infected introduced populations substantially less and crabs in introduced regions were larger and exhibited a greater biomass. Our results are consistent with the general prediction that introduced species suffer less from parasites compared to populations where they are native. This may partly explain why the green crab is such a successful invader and, subsequently, why it is a pest in so many places.     

The Development of Play in Preschoolers

The motives of play activity constitute a key question. It is no accident that views on play diverge most conspicuously with regard to the the stimuli leading to play. Theories of satisfaction, pleasure, internal primary drives and self-affirmation—all "in-depth theories"—are essentially theories of the motivating forces that give rise to play. The principal flaw in these conceptions is how they construe the motivating forces of play: they are situated in the subject, in the child and in the child's experiences. These theories discount the fact that these experiences are but secondary to an activity, i.e., they are symptomatic in that they indicate the activity is indeed taking place, but they tell us nothing about the real, objective, stimuli of the activity.     

Living krill,zooplankton and experimental investigations: a discourse on the role of krill and their experimental study in marine ecology

Krill occupy critical positions in a many marine ecosystems and have been the subject of a number of concerted studies yet there are large areas of their biology that still remain a mystery. Most species of krill are open ocean animals, which makes direct observation and sampling difficult. Krill also exhibit a number of physiological and behavioural attributes which frustrate attempts to understand their life history. Krill are conceptually difficult to come to terms with; they are obviously different from larger marine organisms such as squid, fish, whales and fish yet they are also quite distinct from those animals classed as zooplankton such as copepods. Despite these differences they have most often been grouped with zooplankton and have been studied using techniques developed for animals which are orders of magnitude smaller than they. This mismatch has affected our view of their interactions with the physical world and also affects their perceived trophic interactions. Their size and mobility also interferes with our ability to sample them effectively and thus to develop our appreciation of their true role in the marine ecosystem. Understanding how intermediate-sized animals, such as krill, function in aquatic ecosystem is critical to better management of the marine environment.