Effect of environmental acidity and alkalinity on the physiology of Tilapia mossambica during acclimation

The pattern of carbohydrate metabolism in the muscle of the freshwater fish, Tilapia mossambica (Peters) varied according to the pH of the environmental medium. On acclimation to a more acidic water, the white muscle showed an elevated glycogen content with suppressed glycolysis. In contrast, the muscle tissue showed an accelerated glycolytic pathway with the accumulation of metabotic acids on acclimation to a basic water. In an acidic medium phosphorylase activity was inhibited with an elevated LDH activity, while the reverse pattern was observed in an alkaline medium. The oxidative pathway was elevated in both. Acclimation to acidic and basic environmental waters leads to an adaptive compensatory mechanisms providing increased resistance capacity to the fish under pH stress.     

Evolutionary stable sets in mixed-strategist models

Evolutionary stable sets are used as an extension of the concept of an evolutionarily stable strategy (ESS). They have, as sets, essentially the same properties as ordinary ESSs. Here, ES sets are applied to the characterization of what will happen in an asexual population of mixed-strategists under frequency-dependent selection. Such a population will tend to establish some state, usually not a unique one, that belongs to an ES set. For an important class of widely used mixed-strategist models, ES sets are found to comprise just those population states that allow the possible behavioural acts to be equally successful, or, to put it more precisely, that establish an evolutionarily stable population strategy.     

Opposite allosteric mechanisms in TetR and CAP

Regulation of the DNA binding affinity of an oligomeric protein can be considered to consist of an intrinsic component, in which the affinity of an individual DNA‐binding domain is modulated in response to effector binding, and an extrinsic component, in which the relative position of the protein's two DNA‐binding domains are altered so that they can or cannot contact both half‐site operators simultaneously. We demonstrated directly that the TetR repressor utilizes an extrinsic mechanism and CAP, the catabolite activator protein, utilizes an intrinsic mechanism.     

An Ecosystem Health Index for a large and variable river basin: Methodology,challenges and continuous improvement in Queensland’s Fitzroy Basin

Report cards are an increasingly popular method for summarising and communicating relative environmental performance and ecosystem health, including in aquatic environments. They are usually underpinned by an Ecosystem Health Index (EHI) that combines various individual indicators to produce an overall ecosystem health “score”. As a result of public water quality concerns, an integrated means of monitoring and reporting on aquatic ecosystem health was needed for the Fitzroy Basin in central Queensland, Australia. The Fitzroy Partnership for River Health was formed to address this need, and developed an EHI and report card for the Basin using existing monitoring data collected from various third parties including regulated companies operations and government. At 142,000 square kilometres, the Fitzroy Basin is the largest catchment draining to the World Heritage Listed Great Barrier Reef. The Fitzroy Basin provides an example of how to deliver an effective aquatic ecosystem health reporting system in a large and complex river basin. We describe the methodology used to develop an adaptive EHI for the Fitzroy Basin that addresses variability, complexity and scale issues associated with reporting across large areas. As well, we report how to manage the design and reporting stages given limitations in data collection and scientific understanding.     

A preputial odor imprinted on female mice

Female mice (Mus musculus) which were reared by a preputialectomized female and exposed to an intact male from 14 to 18 days of age preferred the odor of an intact male over that of a preputialectomized male when tested at 15 weeks of age. However, those females which were exposed to an intact male from 28 to 32 days of age preferred the odor of a preputialectomized male over that of an intact male, and those females which were exposed to an intact male from 0 to 4 days of age showed no reliable preferences. Females which were reared by an intact female and exposed a preputialectomized male for 4 days tended to reverse preferences. Females which were exposed to a preputialectomized male from 14 to 18 days of age preferred the odor of a preputialectomized male. However, females which were exposed to a preputialectomized male from 28 to 32 days of age preferred the odor of an intact male, as did females which were exposed to a preputialectomized male from 0 to 4 days.     

Adaptations to training at the individual anaerobic threshold

The individual anaerobic threshold (Th(an)) is the highest metabolic rate at which blood lactate concentrations can be maintained at a steady-state during prolonged exercise. The purpose of this study was to test the hypothesis that training at the Th(an) would cause a greater change in indicators of training adaptation than would training "around" the Th(an). Three groups of subjects were evaluated before, and again after 4 and 8 weeks of training: a control group, a group which trained continuously for 30 min at the Th(an) intensity (SS), and a group (NSS) which divided the 30 min of training into 7.5-min blocks at intensities which alternated between being below the Th(an) [Th(an) -30% of the difference between Th(an) and maximal oxygen consumption (VO2max)] and above the Th(an) (Th(an) +30% of the difference between Th(an) and VO2max). The VO2max increased significantly from 4.06 to 4.27 l.min-1 in SS and from 3.89 to 4.06 l.min-1 in NSS. The power output (W) at Th(an) increased from 70.5 to 79.8% VO2max in SS and from 71.1 to 80.7% VO2max in NSS. The magnitude of change in VO2max, W at Th(an), % VO2max at Th(an) and in exercise time to exhaustion at the pretraining Th(an) was similar in both trained groups. Vastus lateralis citrate synthase and 3-hydroxyacyl-CoA-dehydrogenase activities increased to the same extent in both trained groups. While all of these training-induced adaptations were statistically significant (P < 0.05), there were no significant changes in any of these variables for the control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Active gaze control improves optic flow-based segmentation and steering

An observer traversing an environment actively relocates gaze to fixate objects. Evidence suggests that gaze is frequently directed toward the center of an object considered as target but more likely toward the edges of an object that appears as an obstacle. We suggest that this difference in gaze might be motivated by specific patterns of optic flow that are generated by either fixating the center or edge of an object. To support our suggestion we derive an analytical model that shows: Tangentially fixating the outer surface of an obstacle leads to strong flow discontinuities that can be used for flow-based segmentation. Fixation of the target center while gaze and heading are locked without head-, body-, or eye-rotations gives rise to a symmetric expansion flow with its center at the point being approached, which facilitates steering toward a target. We conclude that gaze control incorporates ecological constraints to improve the robustness of steering and collision avoidance by actively generating flows appropriate to solve the task.     

A suspensory jacket permitting long-term sitting in paraplegic patients

A thoracic suspensory jacket has been used in four patients with recurring ischial pressure sores to transfer the site of skin pressure from the insensate ischial area to the sensory area over the rib cage. This modality is not an alternative to surgery, but rather an adjunct to prevent an early recurrence after an ischial pressure sore has been repaired with a proper surgical procedure.     

Optimization of a stochastically simulated gene network model via simulated annealing

By rearranging naturally occurring genetic components, gene networks can be created that display novel functions. When designing these networks, the kinetic parameters describing DNA/protein binding are of great importance, as these parameters strongly influence the behavior of the resulting gene network. This article presents an optimization method based on simulated annealing to locate combinations of kinetic parameters that produce a desired behavior in a genetic network. Since gene expression is an inherently stochastic process, the simulation component of simulated annealing optimization is conducted using an accurate multiscale simulation algorithm to calculate an ensemble of network trajectories at each iteration of the simulated annealing algorithm. Using the three-gene repressilator of Elowitz and Leibler as an example, we show that gene network optimizations can be conducted using a mechanistically realistic model integrated stochastically. The repressilator is optimized to give oscillations of an arbitrary specified period. These optimized designs may then provide a starting-point for the selection of genetic components needed to realize an in vivo system.     

Environmental Unpredictability and the Value of Social Information for Foraging Starlings

Environmental and behavioral cues are useful sources of information that allow group foraging individuals to improve their foraging success. Few studies to date, however, have examined how varying degrees of environmental unpredictability may affect when and how individuals use the social information they obtain in foraging groups. In this experiment, European starlings (Sturnus vulgaris) were tested to determine in which type of environment, predictable or unpredictable, social information would be the most valuable. Subjects were placed under one of four conditions: an unpredictable environment with either (1) an informing demonstrator bird or (2) an uninforming demonstrator; or a predictable environment with either (3) an informing demonstrator or (4) an uninforming demonstrator. Environmental predictability was manipulated by altering the meaning of available color cues. Subjects in the unpredictable environment that had an informing demonstrator performed significantly better than subjects in an unpredictable environment with an uninforming demonstrator, although only on the second day of testing. Subjects in both the predictable conditions performed similarly to each other. The results suggest that social information is more valuable to individuals in an unpredictable environment than it is in a predictable environment; however, there appears to be a time lag in the ability of the birds to recognize the value of this information.     

Biological properties of two models of calcitonin gene related peptide with idealized amphiphilic alpha-helices of different lengths

Previous studies on calcitonin gene related peptide (CGRP) have demonstrated that it has the characteristics of an amphiphilic peptide, and from an examination of the sequence, we have proposed that it contains an amphiphilic alpha-helix. We have synthesized two analogues of CGRP which have different lengths of idealized amphiphilic alpha-helical secondary structure. The first model, CGRM-1, has been substituted with residues generating an idealized amphiphilic alpha-helix in the region between residues 8 and 25, equivalent to approximately five turns of an alpha-helix. This peptide is not an agonist in any of our bioassays, but it does bind with low affinity to rCGRP receptors in crude liver membranes. Our second model, CGRM-2, has an idealized amphiphilic alpha-helix between residues 8 and 18, which is equivalent to approximately three turns of an alpha-helix. In an in vitro rat vas deferens assay, this peptide is an agonist with a potency one-fourth that of the native hormone. However, the potency of CGRM-2 in an adenylate cyclase assay is much lower, only 1/140th the potency of CGRP. Both model peptides display amphiphilic characteristics commensurate with their design. We conclude that there is an amphiphilic alpha-helix in rCGRP between residues 8 and 18 and that this helix terminates in the vicinity of residue 18.     

Conjugation of cell-penetrating peptides leads to identification of anti-HIV peptides from matrix proteins

Compounds which inhibit the HIV-1 replication cycle have been found amongst fragment peptides derived from an HIV-1 matrix (MA) protein. Overlapping peptide libraries covering the whole sequence of MA were designed and constructed with the addition of an octa-arginyl group to increase their cell membrane permeability. Imaging experiments with fluorescent-labeled peptides demonstrated these peptides with an octa-arginyl group can penetrate cell membranes. The fusion of an octa-arginyl group was proven to be an efficient way to find active peptides in cells such as HIV-inhibitory peptides.     

Further evidence that naloxone acts as an inverse opiate agonist: Implications for drug dependence and withdrawaL

To test if naloxone behaved as an inverse agonist rather than as an antagonist we evaluated its responses in guinea-pig ilea with and without morphine (480 nM, 24 h). In control ilea, naloxone (100 nM) had no effect. In morphine-treated ilea, naloxone as a bolus, but not as an infusion, elicited an abstinence response. Preadministration of naloxone blocked the response to subsequent administrations. Similarly, naloxone failed to produce an abstinence response in ilea pretreated with kappa compounds (bremazocine, U50488 or xorphanol 100 nM) or with kinase inhibitors (H7 or H8 30 μM). These findings can be interpreted in the light of the two-state receptor model if naloxone behaves as an inverse agonist: Incubation with morphine increased the active state of receptors making them susceptible to the inverse agonist (naloxone); exposure to naloxone favored the inactive conformation making them insensitive to further administration of naloxone; kappa compounds behaved as antagonists preventing the response to naloxone; and kinase inhibitors interfered with the active conformation making the system insensitive to naloxone. According to this model, dependence can be viewed as an overexpression of the active receptors and withdrawal as an abrupt change from the active to the inactive state.     

Preventing a surgical complication during cesarean delivery in a morbidly obese patient: a simple apparatus to retract the abdominal panniculus

Obesity is no longer just a "Western" problem, as evidenced by an increase in prevalence of up to 75% in parts of the developing world. It is important to transfer experience from the developed world to developing countries in an attempt to prepare for the inevitable health and economic problems. This case report highlights an unusual intraoperative complication that has medical and medico-legal implications. A simple apparatus designed to retract the panniculus of an obese patient might reduce complications when performing abdominal surgery in such cases.     

Introduction to the principles and applications of biosensors

A biosensor is an analytical device that responds to an analyte in an appropriate sample and interprets its concentration as an electrical signal via a suitable combination of a biological recognition system and an electrochemical transducer. As a result of recent scientific and technological progress, such devices are likely to play an increasingly important role in generating analytical information in all sectors of human endeavour, from medicine to the military. In particular, biosensors will form the basis of cheap, simple devices for acquiring chemical information, bringing sophisticated analytical capabilities to the non-specialist and general public alike. The market opportunities for the rapid exploitation of novel developments in this sector are substantial. Biosensor research is also likely to have a significant impact on the development of modern electronics.     

The leaf-clipping display: A newly-discovered expressive gesture in wild chimpanzees

Chimpanzees of the Mahale Mountains, Tanzania were discovered to show an expressive gesture using leaves, termed as “leaf-clipping display”. This behavioural signal is directed by an adult male to an estrous female as a possessive behaviour, or by an adolescent male as a courtship display, or by an estrous female to an adolescent male also as a solicitation of copulation. The signal also is used toward human observers as a signal of food-demanding. This behaviour pattern might originate in a displacement tool-making behaviour in conflict situations. The leaf-clipping display has not been observed in any other chimpanzee populations studied, and may probably be one example of the tradition drift in wild chimpanzees.     

Locating a compact odor source using a four-channel insect electroantennogram sensor

Here we demonstrate the feasibility of using an array of live insects to detect concentrated packets of odor and infer the location of an odor source (～15 m away) using a backward Lagrangian dispersion model based on the Langevin equation. Bayesian inference allows uncertainty to be quantified, which is useful for robotic planning. The electroantennogram (EAG) is the biopotential developed between the tissue at the tip of an insect antenna and its base, which is due to the massed response of the olfactory receptor neurons to an odor stimulus. The EAG signal can carry tens of bits per second of information with a rise time as short as 12 ms (K A Justice 2005 J. Neurophiol. 93 2233-9). Here, instrumentation including a GPS with a digital compass and an ultrasonic 2D anemometer has been integrated with an EAG odor detection scheme, allowing the location of an odor source to be estimated by collecting data at several downwind locations. Bayesian inference in conjunction with a Lagrangian dispersion model, taking into account detection errors, has been implemented resulting in an estimate of the odor source location within 0.2 m of the actual location.     

Focus: Vaccines: Achieving Global Vaccine Equity: The Case for an International Pandemic Treaty

This paper presents an ethical argument in support of an international Pandemic Treaty. It argues that an international Pandemic Treaty is the best way to mark progress on global vaccine equity and broader issues of global pandemic preparedness and response which came to light during the coronavirus disease 2019 (COVID-19) pandemic. Section I evaluates principles of multilateral charity, national security, and international diplomacy standardly invoked in debates about global vaccine allocation and argues that these approaches fall short. Section II explicates notions of solidarity, duties to the least well-off, and mutual aid as ethical values more fitting for an era of emerging infectious diseases. Section III relates the discussion to an international Pandemic Treaty and presents legal, pragmatic, and ethical reasons to support it. The paper concludes that in an interconnected world, fair sharing of vaccines between nations is morally mandatory.