Attitudinal reciprocity in food sharing among brown capuchin monkeys

Capuchin monkeys (Cebus apella) share food even if separated by a mesh restraint. Pairs of capuchins were moved into a test chamber in which one of them received apple pieces for 20 min, and the other received carrot pieces for the next 20 min. Previous research had shown a correlation between the rate of food transfer in both directions across female-female dyads. The present study confirmed this result. Reciprocity across dyads can be explained, however, by symmetry in affiliative and tolerant tendencies between two individuals, provided these tendencies determine food sharing. The present study was designed to exclude this symmetry-based explanation by testing each pair (N=16) of adult females on six separate occasions. There existed a significant covariation across tests of sharing in both dyadic directions, a result unexplained by relationship symmetry. Moreover, control procedures (i.e. testing of a food possessor without a partner, or testing of two individuals with the same food or two different foods at the same time) indicated that behaviour during food trials is not fully explained by mutual attraction or aversion. The monkeys take the quality of their own and the partner's food into account, and possessors limit transfers of high-quality foods. Instead of a symmetry-based reciprocity explanation, a mediating role of memory is suggested, and a mirroring of social attitude between partners. Copyright 2000 The Association for the Study of Animal Behaviour.     

Effects of chronic low dose rotenone treatment on human microglial cells

Background

Exposure to toxins/chemicals is considered to be a significant risk factor in the pathogenesis of Parkinson's disease (PD); one putative chemical is the naturally occurring herbicide rotenone that is now used widely in establishing PD models. We, and others, have shown that chronic low dose rotenone treatment induces excessive accumulation of Reactive Oxygen Species (ROS), inclusion body formation and apoptosis in dopaminergic neurons of animal and human origin. Some studies have also suggested that microglia enhance the rotenone induced neurotoxicity. While the effects of rotenone on neurons are well established, there is little or no information available on the effect of rotenone on microglial cells, and especially cells of human origin. The aim of the present study was to investigate the effects of chronic low dose rotenone treatment on human microglial CHME-5 cells.

Methods

We have shown previously that rotenone induced inclusion body formation in human dopaminergic SH-SY5Y cells and therefore used these cells as a control for inclusion body formation in this study. SH-SY5Y and CHME-5 cells were treated with 5 nM rotenone for four weeks. At the end of week 4, both cell types were analysed for the presence of inclusion bodies, superoxide dismutases and cell activation (only in CHME-5 cells) using Haematoxylin and Eosin staining, immunocytochemical and western blotting methods. Levels of active caspases and ROS (both extra and intra cellular) were measured using biochemical methods.

Conclusion

The results suggest that chronic low dose rotenone treatment activates human microglia (cell line) in a manner similar to microglia of animal origin as shown by others. However human microglia release excessive amounts of ROS extracellularly, do not show excessive amounts of intracellular ROS and active caspases and most importantly do not show any protein aggregation or inclusion body formation. Human microglia appear to be resistant to rotenone (chronic, low dose) induced damage.

     

Murine Embryonic Stem Cell Plasticity Is Regulated through Klf5 and Maintained by Metalloproteinase MMP1 and Hypoxia

Mouse embryonic stem cells (mESCs) are expanded and maintained pluripotent in vitro in the presence of leukemia inhibitory factor (LIF), an IL6 cytokine family member which displays pleiotropic functions, depending on both cell maturity and cell type. LIF withdrawal leads to heterogeneous differentiation of mESCs with a proportion of the differentiated cells apoptosising. During LIF withdrawal, cells sequentially enter a reversible and irreversible phase of differentiation during which LIF addition induces different effects. However the regulators and effectors of LIF–mediated reprogramming are poorly understood. By employing a LIF-dependent ‘plasticity’ test, that we set up, we show that Klf5, but not JunB is a key LIF effector. Furthermore PI3K signaling, required for the maintenance of mESC pluripotency, has no effect on mESC plasticity while displaying a major role in committed cells by stimulating expression of the mesodermal marker Brachyury at the expense of endoderm and neuroectoderm lineage markers. We also show that the MMP1 metalloproteinase, which can replace LIF for maintenance of pluripotency, mimics LIF in the plasticity window, but less efficiently. Finally, we demonstrate that mESCs maintain plasticity and pluripotency potentials in vitro under hypoxic/physioxic growth conditions at 3% O₂ despite lower levels of Pluri and Master gene expression in comparison to 20% O₂.     

Capuchins do cooperate: the advantage of an intuitive task

We used a cooperative pulling task to examine proximate aspects of cooperation in captive brown capuchin monkeys, Cebus apella. Specifically, our goal was to determine whether capuchins can learn the contingency between their partner's participation in a task and its successful completion. We examined whether the monkeys visually monitored their partners and adjusted pulling behaviour according to their partner's presence. Results on five same-sex pairs of adults indicate that (1) elimination of visual contact between partners significantly decreased success, (2) subjects glanced at their partners significantly more in cooperative tests than in control tests in which no partner-assistance was needed, and (3) they pulled at significantly higher rates when their partner was present rather than absent. Therefore, in contrast to a previous report by Chalmeau et al. (1997, Animal Behaviour, 54, 1215-1225), cooperating capuchins do seem able to take the role of their partner into account. However, the type of task used may be an important factor affecting the level of coordination achieved. Copyright 2000 The Association for the Study of Animal Behaviour.     

Addition of exogenous SOD1 aggregates causes TDP-43 mislocalisation and aggregation

ALS is characterised by a focal onset of motor neuron loss, followed by contiguous outward spreading of pathology throughout the nervous system, resulting in paralysis and death generally within a few years after diagnosis. The aberrant release and uptake of toxic proteins including SOD1 and TDP-43 and their subsequent propagation, accumulation and deposition in motor neurons may explain such a pattern of pathology. Previous work has suggested that the internalization of aggregates triggers stress granule formation. Given the close association of stress granules and TDP-43, we wondered whether internalisation of SOD1 aggregates stimulated TDP-43 cytosolic aggregate structures. Addition of recombinant mutant G93A SOD1 aggregates to NSC-34 cells was found to trigger a rapid shift of TDP-43 to the cytoplasm where it was still accumulated after 48 h. In addition, SOD1 aggregates also triggered cleavage of TDP-43 into fragments including a 25 kDa fragment. Collectively, this study suggests a role for protein aggregate uptake in TDP-43 pathology.     

Feedback equilibrium control during human standing

Equilibrium maintenance during standing in humans was investigated with a 3-joint (ankle, knee and hip) sagittal model of body movement. The experimental paradigm consisted of sudden perturbations of humans in quiet stance by backward displacements of the support platform. Data analysis was performed using eigenvectors of motion equation. The results supported three conclusions. First, independent feedback control of movements along eigenvectors (eigenmovements) can adequately describe human postural responses to stance perturbations. This conclusion is consistent with previous observations (Alexandrov et al., 2001b) that these same eigenmovements are also independently controlled in a feed-forward manner during voluntary upper-trunk bending. Second, independent feedback control of each eigenmovement is sufficient to provide its stability. Third, the feedback loop in each eigenmovement can be modeled as a linear visco-elastic spring with delay. Visco-elastic parameters and time-delay values result from the combined contribution of passive visco-elastic mechanisms and sensory systems of different modalities     

A multiorganism based method for Bayesian gene network estimation

The primary goal of this article is to infer genetic interactions based on gene expression data. A new method for multiorganism Bayesian gene network estimation is presented based on multitask learning. When the input datasets are sparse, as is the case in microarray gene expression data, it becomes difficult to separate random correlations from true correlations that would lead to actual edges when modeling the gene interactions as a Bayesian network. Multitask learning takes advantage of the similarity between related tasks, in order to construct a more accurate model of the underlying relationships represented by the Bayesian networks. The proposed method is tested on synthetic data to illustrate its validity. Then it is iteratively applied on real gene expression data to learn the genetic regulatory networks of two organisms with homologous genes.