Behavioral and Neurogenomic Responses to Acoustic and Visual Sexual Cues are Correlated in Female Torrent Frogs

Diverse a nimal species use multimodal communica tion signals to coordina te reproductive behavior.Despite active research in this field,the brain mechanisms underlying multimodal communication remain poorly understood.Similar to humans and many mammalian species,anurans often produce auditory signals accompanied by conspicuous visual cues(e.g.,vocal sac inflation).In this study,we used video playbacks to determine the role of vocal-sac inflation in little torrent frogs(Amolops torrentis).Then we exposed females to blank,visual,auditory,and audiovisual stimuli and analyzed whole brain tissue gene expression changes using RNAseq.The results showed that both auditory cues(i.e.,male advertisement calls)and visual cues were attractive to female frogs,although auditory cues were more attractive than visual cues.Females preferred simultaneous bimodal cues to unimodal cues.The hierarchical clustering of differentially expressed genes showed a close relationship between neurogenomic states and momentarily expressed sexual signals.We also found that the Gene Ontology terms and KEGG pathways involved in energy metabolism were mostly increased in blank contrast versus visual,acoustic,or audiovisual stimuli,indicating that brain energy use may play an important role in response to these stimuli.In sum,behavioral and neurogenomic responses to acoustic and visual cues are correlated in female little torrent frogs.     

Responses to Vocalizations and Auditory Controls in the Human Newborn Brain

In the adult brain, speech can recruit a brain network that is overlapping with, but not identical to, that involved in perceiving non-linguistic vocalizations. Using the same stimuli that had been presented to human 4-month-olds and adults, as well as adult macaques, we sought to shed light on the cortical networks engaged when human newborns process diverse vocalization types. Near infrared spectroscopy was used to register the response of 40 newborns'' perisylvian regions when stimulated with speech, human and macaque emotional vocalizations, as well as auditory controls where the formant structure was destroyed but the long-term spectrum was retained. Left fronto-temporal and parietal regions were significantly activated in the comparison of stimulation versus rest, with unclear selectivity in cortical activation. These results for the newborn brain are qualitatively and quantitatively compared with previous work on newborns, older human infants, adult humans, and adult macaques reported in previous work.     

Assessing Social Engagement in Heterogeneous Groups of Zebrafish: A New Paradigm for Autism-Like Behavioral Responses

Because of its highly developed social character, zebrafish is a promising model system for the study of the genetic and neurochemical basis of altered social engagement such as is common in autism and schizophrenia. The traditional shoaling paradigm investigates social cohesion in homogeneous groups of zebrafish. However, the social dynamics of mixed groups is gaining interest from a therapeutic point of view and thus warrants animal modeling. Furthermore, mutant zebrafish are not always available in large numbers. Therefore, we developed a new paradigm that allows exploring shoaling in heterogeneous groups. The effects of MK-801, a non-competitive antagonist of the glutamate N-methyl-D-aspartate (NMDA) receptor, on social cohesion were studied to evaluate the paradigm. The drug has previously been shown to mimic aspects of autism and schizophrenia. Our results show that a single MK-801-treated zebrafish reduced social cohesion of the entire shoal drastically. Preliminary observations suggest that the social dynamics of the shoal as a whole was altered.     

Recording Behavioral Responses to Reflection in Crayfish

Social behavior depends on sensory input from the visual, mechanical and olfactory systems. One important issue concerns the relative roles of each sensory modality in guiding behavior. The role of visual inputs has been examined by isolating visual stimuli from mechanical and chemosensory stimuli. In some studies (Bruski & Dunham, 1987: Delgado-Morales et al., 2004) visual inputs have been removed with blindfolds or low light intensity, and effects of remaining sensory modalities have been elucidated. An alternative approach is to study the effects of visual inputs in the absence of any appropriate mechanical and chemosensory cues. This approach aims to identify the exclusive role of visual inputs. We have used two methods to provide visual stimuli to crayfish without providing chemical and mechanical cues. In one method, crayfish are videotaped in an aquarium where half of the walls are covered in mirrors to provide a reflective environment, and the other half are covered in a non-reflective (matte finish) plastic. This gives the crayfish a choice between reflective and non-reflective environments. The reflective environment provides visual cues in the form of reflected images of the crayfish as it moves throughout half of the tank; these visual cues are missing from the non-reflective half of the tank. An alternative method is to videotape the behavior of crayfish in an aquarium separated by a smaller chamber at each end, with a crayfish in one small chamber providing visual cues and an inert object in the opposite small chamber providing visual input from a non-moving, non-crayfish source. Our published results indicate that responses of crayfish to the reflective environment depend on socialization and dominance rank. Socialized crayfish spent more time in the reflective environment and exhibited certain behaviors more frequently there than in the non-reflective environment; isolated crayfish showed no such differences. Crayfish that were housed in same-sex pairs developed a social rank of either dominant or subordinate. Responses to reflection differed between dominant and subordinate crayfish (May & Mercier, 2006; May & Mercier, 2007). Dominant crayfish spent more time on the reflective side, entered reflective corners more frequently and spent more time in reflective corners compared to the non-reflective side. Subordinate crayfish walked in reverse more often on the reflective side than on the non-reflective side. Preliminary data suggest similar effects from visual cues provided by a crayfish in a small adjoining chamber (May et al., 2008).Download video file.^{(129M, mp4)}     

Sucralose Induces Biochemical Responses in Daphnia magna

The intense artificial sweetener sucralose has no bioconcentration properties, and no adverse acute toxic effects have been observed in standard ecotoxicity tests, suggesting negligible environmental risk. However, significant feeding and behavioural alterations have been reported in non-standard tests using aquatic crustaceans, indicating possible sublethal effects. We hypothesized that these effects are related to alterations in acetylcholinesterase (AChE) and oxidative status in the exposed animals and investigated changes in AChE and oxidative biomarkers (oxygen radical absorbing capacity, ORAC, and lipid peroxidation, TBARS) in the crustacean Daphnia magna exposed to sucralose (0.0001–5 mg L⁻¹). The sucralose concentration was a significant positive predictor for ORAC, TBARS and AChE in the daphnids. Moreover, the AChE response was linked to both oxidative biomarkers, with positive and negative relationships for TBARS and ORAC, respectively. These joint responses support our hypothesis and suggest that exposure to sucralose may induce neurological and oxidative mechanisms with potentially important consequences for animal behaviour and physiology.     

Behavioral and Physiological Responses to Emersion in Freshwater Bivalves

SYNOPSIS. Littoral lentic and shallow lotic freshwater habitatsare unpredictable in periodicity and duration of shore emersion.As a result, freshwater bivalves have evolved extensive capacitiesto withstand prolonged emersion. Valve movement behaviors allowemersed bivalves to control rate of water loss while maintainingat least partial aerial gas exchange; these behaviors are affectedby environmental variables such as temperature and relativehumidity. Aerial oxygen uptake is associated directly with valveventilatory behaviors and mantle edge exposure. Such behaviorsare often phasic, indicative of oxygen "debt" payment. Lackingeffective hemolymph buffer, respiratory acidosis during emersionis compensated by shell carbonate stores allowing hemolymphP_CO2 to rise to levels facilitating diffusion of CO₂ to theenvironment. During emersion, hemolymph calcium can increasefour fold while Na and Cl are tightly regulated. Ammonia productionceases in emersed bivalves. It resumes on reimmersion, indicativeof heavy reliance on non-protein catabolism during emersion.Some emersion adaptations of freshwater species appear to bemodifications of those displayed by intertidal and estuarinebivalves, while others appear independently evolved to allowsurvival of the extreme emersion periods associated with lifein shallow freshwaters.     

A Calcium-Receptor Agonist Induces Gustatory Neural Responses in Bullfrogs

The effect of calcium-sensing receptor (CaR) agonists on frog gustatory responses was studied using glossopharyngeal nerve recording and whole-cell patch-clamp recording of isolated taste disc cells. Calcimimetic NPS R-467 dissolved in normal saline solution elicited a large transient response in the nerve. The less active enantiomer of the compound, NPS S-467 induced only a small neural response. The EC₅₀ for NPS R-467 was about 20 μM. Cross-adaptation experiments were performed to examine the effect of 30 μM NPS R-467 and 100 μM quinine on the gustatory neural response. The magnitude of the R-467-induced response after adaptation to quinine was approximately equal to that after adaptation to normal saline solution, indicating that the receptor site for NPS R-467 is different from the site for quinine. NPS R-467 (100 μM) also induced an inward current accompanied with conductance increase and large depolarization in two (13%) of 15 rod cells, and a sustained decrease in outward current and small depolarization in six (40%) other rod cells. NPS S-467 (100 μM) induced a sustained decrease in outward current and depolarization in five (50%) of 10 rod cells. Another calcimimetic cinacalcet (100 μM) induced an inward current accompanied with conductance increase in three (27%) of 11 rod cells. The results suggest that NPS R-467 induces neural responses through cell responses unrelated to a resting K⁺ conductance decrease.     

Clicks and Communication: The Behavioural and Social Contexts of Hector's Dolphin Vocalizations

Hector's dolphins (Cephalorhynchus hectori) have a simple vocal repertoire, consisting almost entirely of ultrasonic clicks. They produce no whistles, and very few audible sounds. To examine acoustic communication in this species I analysed the relationship between click types and behaviour. The proportion of complex click types was greater in large groups, suggesting that these sounds have social significance. Clicks having 2 peaks in their time envelope and two frequency peaks were strongly associated with behaviours indicative of feeding. High pulse rate sounds, in which the repetition rate of ultrasonic clicks was audible as a “cry”, were most strongly associated with aerial behaviours. These data suggest that echo-location is not the sole function of Hector's dolphin clicks, and that echo-location and communication are likely to be closely linked. I hypothesize that dolphins may have the ability to gather information from the echoes of each other's sonar pulses. This may reduce the need for a large number of vocal signals, and may explain the apparent simplicity of the acoustic repertoires of some odontocetes.     

Behavioral Responses of the Social Wasp Polistes myersi to Prey Infected with Fungi Used in Biological Control

Metarhizium anisopliae and Beauveria bassiana are commonly used entomopathogenic fungi, but their non-target effects over generalist predatory insects, which can contribute to pest control, are not well known. We studied the capacity of the social wasp Polistes myersi to detect the pathogens in either a powdered form or in Galleria mellonella larvae infected with either of the two pathogens offered as prey. The effects of these treatments were compared considering wasp behaviors such as prey preference, frequency, duration and transitions of both hunting and grooming behaviors. Additionally, the effects of each entomopathogenic fungus on the wasp’s mortality were measured. Wasps seem not to detect the pathogens in powdered form but preferred healthy over infected larvae. Seventeen behavioral units for hunting and 34 for grooming were recognized. There were no differences in grooming frequency but there were significant differences on grooming duration, hunting behaviors and the patterns of transitions. Exposure of wasp colonies to either B. bassiana or M. anisopliae had no detectable impact on the mortality of adults, but mortality of larvae increased. For the first time, this study documented behavioral changes that indicated the capacity of social wasps to detect pathogens before physical contact and the display of hygienic strategies once contact occurs. The study also suggested a potential non-target effect of these entomopathogenic fungi on a generalist predator.

     

Intranigral Iron Injection Induces Behavioral and Biochemical "Parkinsonism" in Rats

Elevated iron concentrations in the substantia nigra (SN) pars compacta have been implicated in the development of idiopathic Parkinson's disease. Because, as a transitional metal, iron promotes free radical formation, the role of iron in the degeneration of the nigrostriatal dopamine neurons in Parkinson's disease has received much attention. This study further investigates the cytotoxic effects of iron in the SN. Various concentrations of FeCl3 (1, 5, and 50 micrograms of Fe3+ in 5 microliters) were unilaterally injected into the SN of adult rats. The two lower doses of iron had no effect on striatal dopamine levels or on the behavioral responses of the rats. However, injection of 50 micrograms of Fe3+ resulted in a substantial selective decrease of striatal dopamine (95%), 3,4-dihydroxyphenylacetic acid (82%), and homovanillic acid (45%), without any change in norepinephrine concentration. Dopamine-related behavioral responses, such as spontaneous movements in a novel space and rearing, were significantly impaired, whereas amphetamine administration induced ipsilateral rotation in the iron-treated rats. The present study indicates that the nigrostriatal dopamine neurons are susceptible to the presence of ionic iron and thus supports the assumption that iron initiates dopaminergic neurodegeneration in Parkinson's disease.     

Limiting Energy Dissipation Induces Glassy Kinetics in Single-Cell High-Precision Responses

Single cells often generate precise responses by involving dissipative out-of-thermodynamic-equilibrium processes in signaling networks. The available free energy to fuel these processes could become limited depending on the metabolic state of an individual cell. How does limiting dissipation affect the kinetics of high-precision responses in single cells? I address this question in the context of a kinetic proofreading scheme used in a simple model of early-time T cell signaling. Using exact analytical calculations and numerical simulations, I show that limiting dissipation qualitatively changes the kinetics in single cells marked by emergence of slow kinetics, large cell-to-cell variations of copy numbers, temporally correlated stochastic events (dynamic facilitation), and ergodicity breaking. Thus, constraints in energy dissipation, in addition to negatively affecting ligand discrimination in T cells, can create a fundamental difficulty in determining single-cell kinetics from cell-population results.     

Information Recovery in Behavioral Networks

In the context of agent based modeling and network theory, we focus on the problem of recovering behavior-related choice information from origin-destination type data, a topic also known under the name of network tomography. As a basis for predicting agents'' choices we emphasize the connection between adaptive intelligent behavior, causal entropy maximization, and self-organized behavior in an open dynamic system. We cast this problem in the form of binary and weighted networks and suggest information theoretic entropy-driven methods to recover estimates of the unknown behavioral flow parameters. Our objective is to recover the unknown behavioral values across the ensemble analytically, without explicitly sampling the configuration space. In order to do so, we consider the Cressie-Read family of entropic functionals, enlarging the set of estimators commonly employed to make optimal use of the available information. More specifically, we explicitly work out two cases of particular interest: Shannon functional and the likelihood functional. We then employ them for the analysis of both univariate and bivariate data sets, comparing their accuracy in reproducing the observed trends.     

Nitrogen Under-and Over-supply Induces Distinct Protein Responses in Maize Xylem Sap

Xylem sap primarily transports water and mineral nutrients such as nitrogen(N)from roots to shoots in vascular plants.However,it remains largely unknown how nitrogenous compounds,especially proteins in xylem sap,respond to N under-or over-supply.We found that reducing N supply increased amino-N percentage of total N in maize(Zea mays L.)xylem sap.Proteomic analysis showed that 23 proteins in the xylem sap of maize plants,including 12 newly identified ones,differentially accumulated in response to various N supplies.Fifteen of these 23 proteins were primarily involved in general abiotic or biotic stress responses,whereas the other five proteins appeared to respond largely to N under-or over-supply,suggesting distinct protein responses in maize xylem upon N under-and over-supply.Furthermore,one putative xylanase inhibitor and two putative O-glycosyl hydrolases had preferential gene expression in shoots.     

Circuit-Host Coupling Induces Multifaceted Behavioral Modulations of a Gene Switch

Quantitative modeling of gene circuits is fundamentally important to synthetic biology, as it offers the potential to transform circuit engineering from trial-and-error construction to rational design and, hence, facilitates the advance of the field. Currently, typical models regard gene circuits as isolated entities and focus only on the biochemical processes within the circuits. However, such a standard paradigm is getting challenged by increasing experimental evidence suggesting that circuits and their host are intimately connected, and their interactions can potentially impact circuit behaviors. Here we systematically examined the roles of circuit-host coupling in shaping circuit dynamics by using a self-activating gene switch as a model circuit. Through a combination of deterministic modeling, stochastic simulation, and Fokker-Planck equation formalism, we found that circuit-host coupling alters switch behaviors across multiple scales. At the single-cell level, it slows the switch dynamics in the high protein production regime and enlarges the difference between stable steady-state values. At the population level, it favors cells with low protein production through differential growth amplification. Together, the two-level coupling effects induce both quantitative and qualitative modulations of the switch, with the primary component of the effects determined by the circuit’s architectural parameters. This study illustrates the complexity and importance of circuit-host coupling in modulating circuit behaviors, demonstrating the need for a new paradigm—integrated modeling of the circuit-host system—for quantitative understanding of engineered gene networks.     

The Importance of Social Condition in the Hormonal and Behavioral Responses to an Acute Social Stressor in the Male Siberian Dwarf Hamster (Phodopus sungorus)

Social condition is an important factor in determining the behavioral and hormonal responses to a social stressor in the Siberian dwarf hamster (Phodopus sungorus). We predict that males housed with a female or a family (female and pups) will show an increase in the magnitude of the behavioral and hormonal responses to a male intruder compared to those of individually housed males. Three treatment groups were studied: individually housed males that had been previously group-housed in same-sex colonies (males,n= 10), males housed with a female (male + female,n= 9), and males housed with their female and pups (male + family,n= 12). Males were monitored for aggressive behavior toward an intruder male for 10 min. Blood samples were taken at baseline and after the encounter. Male + female and male + family groups spent more time in aggressive behavior (P< 0.05), such as attacking (P< 0.05) and fighting (P<0.05), than did individually housed males. These same groups showed significant increases in plasma cortisol after the encounter (P< 0.01) whereas there were no significant increases in plasma cortisol in solitary males. All groups showed significantly lower levels of plasma testosterone (male,P< 0.001, male + female,P< 0.05; male + family,P< 0.01) whereas a significant increase in prolactin occurred only in the male + family group (P< 0.05). There was a significant positive correlation between postencounter cortisol levels and total number of minutes spent in aggressive behavior (P< 0.05). These results demonstrate that the introduction of a novel intruder male results in an activation of the hypothalamic–pituitary–adrenocortical axis and a suppression of the reproductive axis. Furthermore, pairing of a male with a female alters the behavioral and hormonal responses to an intruder male.