Explaining interindividual differences in toddlers' collaboration with unfamiliar peers: individual, dyadic, and social factors

During their third year of life, toddlers become increasingly skillful at coordinating their actions with peer partners and they form joint commitments in collaborative situations. However, little effort has been made to explain interindividual differences in collaboration among toddlers. Therefore, we examined the relative influence of distinct individual, dyadic, and social factors on toddlers' collaborative activities (i.e., level of coordination and preference for joint activity) in joint problem-solving situations with unfamiliar peer partners (n = 23 dyads aged M = 35.7 months). We analyzed the dyadic nonindependent data with mixed models. Results indicated that mothers' expectations regarding their children's social behaviors significantly predicted toddlers' level of coordination. Furthermore, the models revealed that toddlers' positive mutual experiences with the unfamiliar partner assessed during an initial free play period (Phase 1) and their level of coordination in an obligatory collaboration task (Phase 2) promoted toddlers' preference for joint activity in a subsequent optional collaboration task (Phase 3). In contrast, children's mastery motivation and shyness conflicted with their collaborative efforts. We discuss the role of parents' socialization goals in toddlers' development toward becoming active collaborators and discuss possible mechanisms underlying the differences in toddlers' commitment to joint activities, namely social preferences and the trust in reliable cooperation partners

Expression of acid-sensing ion channels and selection of reference genes in mouse and naked mole rat.

Acid-sensing ion channels (ASICs) are a family of ion channels comprised of six subunits encoded by four genes and they are expressed throughout the peripheral and central nervous systems. ASICs have been implicated in a wide range of physiological and pathophysiological processes: pain, breathing, synaptic plasticity and excitotoxicity. Unlike mice and humans, naked mole-rats do not perceive acid as a noxious stimulus, even though their sensory neurons express functional ASICs, likely an adaptation to living in a hypercapnic subterranean environment. Previous studies of ASIC expression in the mammalian nervous system have often not examined all subunits, or have failed to adequately quantify expression between tissues; to date there has been no attempt to determine ASIC expression in the central nervous system of the naked mole-rat. Here we perform a geNorm study to identify reliable housekeeping genes in both mouse and naked mole-rat and then use quantitative real-time PCR to estimate the relative amounts of ASIC transcripts in different tissues of both species. We identify RPL13A (ribosomal protein L13A) and CANX (calnexin), and β-ACTIN and EIF4A (eukaryotic initiation factor 4a) as being the most stably expressed housekeeping genes in mouse and naked mole-rat, respectively. In both species, ASIC3 was most highly expressed in dorsal root ganglia (DRG), and ASIC1a, ASIC2b and ASIC3 were more highly expressed across all brain regions compared to the other subunits. We also show that ASIC4, a proton-insensitive subunit of relatively unknown function, was highly expressed in all mouse tissues apart from DRG and hippocampus, but was by contrast the lowliest expressed ASIC in all naked mole-rat tissues

Using an agent-based model to simulate the development of risk behaviors during adolescence

Adolescents tend to adopt behaviors that are similar to those of their friends, and also tend to become friends with peers that have similar interests and behaviors. This tendency towards homogeneity applies not only to conventional behaviors such as working for school and participating in sports activities, but also to risk behaviors such as drug use, oppositional behavior or unsafe sex. The current study aims at building an agent model to answer the following related questions: How do friendship groups evolve and what is the role of behavioral similarity in friendship formation? How does homogeneity among peers emerge, with regard to conventional as well as risk behaviors? On the basis of the theoretical and empirical literature on friendship selection and influences on risk behavior during adolescence we first developed a conceptual framework, which was then translated into a mathematical model of a dynamic system and implemented as an agent-based computer simulation consisting of simple behavioral rules and principles. Each agent in the model holds distinct property matrices including an individual behavioral profile with a list of risky (i.e., alcohol use, aggressiveness, soft drugs) and conventional behaviors (i.e., school attendance, sports, work). The computer model simulates the development, during one school year, of a social network (i.e. formation of friendships and cliques), the (dyadic) interactions between pupils and their behavioral profiles. During the course of simulation, the agents' behavioral profiles change on the basis of their interactions resulting in individual developmental curves of conventional and risk behaviors. These profiles are used to calculate the (behavioral) similarity and differences between the various agents. Generally, the model output is analyzed by means of visual inspection (i.e., plotting developmental curves of behavior and social networks), systematic comparison and by calculating additional measures (i.e., using specific social analysis software packages). Simulation results conclusively indicate model validity. The model simulates qualitative properties currently found in research on adolescent development, namely the role of homophily, the appearance of friendship clusters, and the increase in behavioral homogeneity among friends. The model not only converges with empirical findings, but furthermore helps to explain social psychological phenomena (e.g. the emergence of homophily among adolescents)

The naked mole-rat as an animal model in biomedical research: current perspectives

The naked mole-rat (NMR) is a subterranean rodent that has gained significant attention from the biomedical research community in recent years as molecular mechanisms underlying its unusual biology start to be unraveled. With very low external mortality, NMRs have an unusually long lifespan while showing no signs of aging, such as neurodegeneration or cancer. Furthermore, living underground in large colonies (100 to 300 animals), results in comparatively high carbon dioxide and low oxygen levels, from which NMRs have evolved extreme resistance to both hypoxia and hypercapnia. In this paper we have summarized the latest developments in NMR research and its impact on biomedical research, with the aim of providing a sound background that will inform and inspire further investigations

ASICs and mammalian mechanoreceptor function

It is well established that some members of the Deg/ENaC super family of amiloride sensitive ion channels can participate directly in the transduction of mechanical stimuli by sensory neurons in invertebrates. A large body of work has also implicated the acid sensing ion channels family (ASIC1-4) as participants in regulating mechanoreceptor sensitivity in vertebrates. In this review we provide an overview of the physiological and genetic evidence for involvement of ASICs in mechanosensory function. On balance, the available evidence favors the idea that these channels have an important regulatory role in mechanosensory function. It is striking how diverse the consequences of Asic gene deletion are on mechanosensory function with both gain and loss of function effects being observed depending on sensory neuron type. We conclude that other, as yet unknown, molecular partners of ASIC proteins may be decisive in determining their precise physiological role in mechanosensory neurons. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.Work in the Lewin lab was supported by a senior ERC award (Grant no 294678) and grants from the Deutsche Forschungsgemeinshaft (SFB665 and SFB958). Y-A. B. S. was funded by a fellowship from the Deutsche akademsische Austausch Dienst (DAAD). E. St. J. S. is funded by an Early Career Research Grant from the International Association for the Study of Pain. L-N. S is funded by the BBSRC Doctoral Training Program and the David James studentship

The dorsoanterior brain of adult amphioxus shares similarities in expression profile and neuronal composition with the vertebrate telencephalon

Funder: FP7 People: Marie-Curie Actions; doi: http://dx.doi.org/10.13039/100011264; Grant(s): 229597Abstract: Background: The evolutionary origin of the telencephalon, the most anterior part of the vertebrate brain, remains obscure. Since no obvious counterpart to the telencephalon has yet been identified in invertebrate chordates, it is difficult to trace telencephalic origins. One way to identify homologous brain parts between distantly related animal groups is to focus on the combinatorial expression of conserved regionalisation genes that specify brain regions. Results: Here, we report the combined expression of conserved transcription factors known to specify the telencephalon in the vertebrates in the chordate amphioxus. Focusing on adult specimens, we detect specific co-expression of these factors in the dorsal part of the anterior brain vesicle, which we refer to as Pars anterodorsalis (PAD). As in vertebrates, expression of the transcription factors FoxG1, Emx and Lhx2/9 overlaps that of Pax4/6 dorsally and of Nkx2.1 ventrally, where we also detect expression of the Hedgehog ligand. This specific pattern of co-expression is not observed prior to metamorphosis. Similar to the vertebrate telencephalon, the amphioxus PAD is characterised by the presence of GABAergic neurons and dorsal accumulations of glutamatergic as well as dopaminergic neurons. We also observe sustained proliferation of neuronal progenitors at the ventricular zone of the amphioxus brain vesicle, as observed in the vertebrate brain. Conclusions: Our findings suggest that the PAD in the adult amphioxus brain vesicle and the vertebrate telencephalon evolved from the same brain precursor region in ancestral chordates, which would imply homology of these structures. Our comparative data also indicate that this ancestral brain already contained GABA-, glutamatergic and dopaminergic neurons, as is characteristic for the olfactory bulb of the vertebrate telencephalon. We further speculate that the telencephalon might have evolved in vertebrates via a heterochronic shift in developmental timing

Dioksini i njihova toksičnost za ljude

The term dioxins usually refers to polychlorinated dibenzo-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). As 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) has the highest toxic potential, the toxic potentials of other PCDDs and PCDFs are defined in comparison with it. Human exposure to dioxins can be environmental (background), occupational, or accidental pollution. In the human body, dioxins are in part metabolised and eliminated, and the rest is stored in body fat. People vary in their capacity to eliminate TCDD, but it is also dose-dependent; the elimination rate is much faster at higher than lower levels. The liver microsomal P4501A1 enzyme oxygenates lipophilic chemicals such as dioxins. It is encoded by the CYP1A1 gene. Cytosolic aryl hydrocarbon receptor (AhR) mediates their carcinogenic action. It binds to dioxin, translocates to nucleus and together with hydrocarbon nuclear translocator (ARNT) and xenobiotic responsive element (XRE) increases the expression of CYP1A1. Dioxins are classified as known human carcinogens, but they also cause noncancerous effects like atherosclerosis, hypertension, and diabetes. Long-term exposures to dioxins cause disruption of the nervous, immune, reproductive, and endocrine system. Short-term exposure to high levels impairs the liver function and causes chloracne. The most sensitive population to dioxin exposure are the foetuses and infants. A large number of health effects have been documented in the scientific literature, and they all place dioxins among the most toxic chemicals known to man.Dioksini su skupina kemijskih spojeva koji obuhvaćaju poliklorirane dibenzo-dioksine (PCDD) i poliklorirane dibenzo-furane (PCDF). Najveći toksični potencijal (faktor ekvivalentne toksičnosti) ima 2,3,7,8-TCDD, dok su toksični potencijali drugih PCDD i PCDF određeni u odnosu na njega. Izloženost dioksinima može biti izravna: izloženost dioksinima emitiranim u okoliš kao posljedica nesreće, profesionalna izloženost te neizravna, tzv. pozadinska. Nakon ulaska u ljudski organizam dioksini se djelomično metaboliziraju i eliminiraju, a ostatak se pohranjuje u adipozno tkivo. Postoji određena varijabilnost između ljudi u kapacitetu eliminacije TCDD. Eliminacija TCDD ovisna je o dozi – kod veće izloženosti (izloženost višim koncentracijama) brzina eliminacije je viša nego kod manje izloženosti (izloženost nižim koncentracijama). Enzim P4501A1 najvažniji je u oksigenaciji lipofi lnih supstrata poput dioksina. Kodiran je genom CYP1A1. AhR je stanični receptor koji djeluje kao transkripcijski faktor koji posreduje u njihovu karcinogenom učinku. AhR veže dioksin te se premješta u jezgru gdje zajedno s ARNT (engl. aryl hydrocarbon nuclear translocator) i XRE (engl. xenobiotic responsive element), smještenim u promotorskoj regiji gena za CYP1A1, uzrokuje povećani izražaj CYP1A1. Dioksini su karcinogeni spojevi, ali imaju i nekarcinogene učinke poput ateroskleroze, hipertenzije, dijabetesa, poremećaj živčanog, imunosnog, reproduktivnog i endokrinog sustava, posebice kod kronične izloženosti. Akutna izloženost uzrokuje oštećenja jetre i klorakne. Najosjetljivija skupina izloženosti dioksinu je dojenčad u prenatalnom i postnatalnom razdoblju. U znanstvenoj i stručnoj literaturi dokumentirani su brojni zdravstveni učinci kao posljedice izloženosti dioksinima te ih svi ističu kao jedne od najtoksičnijih kemijskih spojeva