The nucleases of yeast: I. Properties and variability of ribonucleases

• 1.1.Nucleases are located in both ribosomes and supernatant of the yeast, Saccharomyces fragilis X Saccharomyces dodzhanskii. Ribosomes prepared from either exponentially growing cells or stationary cells exhibit nuclease activity with a pH optimum of around 7 which is not inhibited by 0.02 M EDTA, Polyvinylsulfate inhibits only at high concentrations. Nuclease activity in the 105 000 × g supernatant from exponentially growing cells has a pH optimum of around 8 and is severely inhibited by EDTA and polyvinylsulfate. In contrast, supernant nuclease from stationary cells has a pH optimum of around 6 and is only partially inhibited by EDTA.
• 2.2.Supernant nuclear I and II from logarithmic cells have been partially purified. Their pH optimums are 7.4 and 7.6, respectively. Both nucleases are inhibited by EDTA, Zn²⁺, polyvinylsulfate and phosphate. The inhibition of EDTA is reversed by the addition of Mg²⁺. Polyribonucleotides are hydrolysed to di- and trioligonucleotides with 5′-phosphomonoester end groups by both nucleases.

     

How cooperation became the norm

Most of the contributions to Cooperation and Its Evolution grapple with the distinctive challenges presented by the project of explaining human sociality. Many of these puzzles have a ‘chicken and egg’ character: our virtually unparalleled capacity for large-scale cooperation is the product of psychological, behavioural, and demographic changes in our recent evolutionary history, and these changes are linked by complex patterns of reciprocal dependence. There is much we do not yet understand about the timing of these changes, and about the order in which different aspects of human social psychology (co-)evolved. In this review essay, I discuss four such puzzles the volume raises. These concern punishment and norm-psychology, moral judgement and the moral emotions, hierarchy and top-down coercion, and property rights and legal systems.     

Properties of average-conductance cationic channels that mediate cholinergic excitation of guinea-pig ileum myocytes under conditions close to the physiological norm

The properties of cationic channels of an average unitary conductance were studied in guinea-pig ileum smooth muscle cells using a patch-clamp technique in the outside-out configuration. Cationic channels were activated by addition of 200 µM GTPS to an intrapipette solution, which resulted in stable activation of G proteins. The replacement of external cesium-containing (in the absence of Ca²⁺ and Mg²⁺ ions) solution with a more physiological sodium solution containing 2.5 mM Ca²⁺ and 2.0 mM Mg²⁺ led to smaller values of both the amplitude of currents through the unitary cationic channels under study and the probability of the stay of the channel in the open state (P _o ). The drop in current amplitude was related mostly to the blocking effect of bivalent cations, while a decrease in the P _o resulted from the replacement of Cs⁺ with Na⁺. Just a drop in the P _o , which was responsible for approximately 85% of the inhibitory effect, played a crucial role in the suppression of the integral transmembrane current.Neirofiziologiya/Neurophysiology, Vol.36, No.4, pp.281–287, July–August, 2004.     

Group bias in cooperative norm enforcement

A hallmark of human social cognition is the tendency for both adults and children to favour members of their own groups. Critically, this in-group bias exerts a strong influence on cooperative decision-making: people (i) tend to share more with members of their in-group and (ii) differentially enforce fairness norms depending on the group membership of their interaction partners. But why do people show these group biases in cooperation? One possibility is that the enforcement of cooperative norm violations is an evolved mechanism supporting within-group cooperation (Norms-Focused Hypothesis). Alternatively, group bias in cooperation could be a by-product of more general affective preferences for in-group members (Mere Preferences Hypothesis). Here, we appraise evidence from studies of both adults and children with the goal of understanding whether one of these two accounts is better supported by existing data. While the pattern of evidence is complex, much of it is broadly consistent with the Mere Preferences Hypothesis and little is uniquely supportive of the Norms-Focused Hypothesis. We highlight possible reasons for this complexity and suggest ways that future work can continue to help us understand the important relationship between group bias and cooperation.     

The neural signature of social norm compliance

All known human societies establish social order by punishing violators of social norms. However, little is known about how the brain processes the punishment threat associated with norm violations. We use fMRI to study the neural circuitry behind social norm compliance by comparing a treatment in which norm violations can be punished with a control treatment in which punishment is impossible. Individuals' increase in norm compliance when punishment is possible exhibits a strong positive correlation with activations in the lateral orbitofrontal cortex and right dorsolateral prefrontal cortex. Moreover, lateral orbitofrontal cortex activity is strongly correlated with Machiavellian personality characteristics. These findings indicate a neural network involved in social norm compliance that might constitute an important basis for human sociality. Different activations of this network reveal individual differences in the behavioral response to the punishment threat and might thus provide a deeper understanding of the neurobiological sources of pathologies such as antisocial personality disorder.     

Defining tolerance as a norm of reaction

Tolerance of an environmental factor is the ability to maintain fitness in the face of stress imposed by that factor. A tolerant genotype minimizes the decline in fitness from that achieved in a relatively benign environment to that produced in environments with more stressful levels of the factor. Hence, tolerance is a phenotypically plastic characteristic of a genotype that can be assessed only by measuring the genotype's fitness in more than one environment. The genotype's tolerance is characterized by the shape of the fitness reaction norm along the environmental gradient whereas the overall height of the function represents its general vigor. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modeling of mechanoelectric coupling in cardiomyocytes in norm and pathology

We developed mathematical models of the electromechanical function of cardiomyocytes and the simplest mechanically heterogeneous myocardial systems, muscle duplexes. By means of these models we studied the contribution of mechanoelectric feedbacks to the contractile activity of the myocardium in norm and pathology. In particular, we simulated and clarified the effects of mechanical conditions on both the form and the duration of the action potential during contractions. From this standpoint different kinds of myocardium mechanical heterogeneity were analyzed. As we have established, the latter can play both a positive and a negative role, depending on the distribution of mechanical nonuniformity and the sequence of activation of heterogeneous myocardium system elements. By means of the same models, we studied the contribution of mechanical factors to the arrhythmogenicity in the case of the cardiomyocyte calcium overload caused by the attenuation of the sodium-potassium pump and outlined the ways for correcting the contractile function in these disturbances.     

Structure and function of enteric alpha defensins in norm and pathology

This review summarizes currently available data on enteric alpha defensins structure, their functions in the innate and adaptive immunity systems and the role in development of intestinal illnesses.     

To detect and correct: norm violations and their enforcement

Compliance with social norms requires neural signals related both to the norm and to deviations from it. Recent work using economic games between two interacting subjects has uncovered brain responses related to norm compliance and to an individual's strategic outlook during the exchange. These brain responses possess a provocative relationship to those associated with negative emotional outcomes, and hint at computational depictions of emotion processing.     

Social norm compliance as a signaling system. I. Studies of fitness-related attributions consequent on everyday norm violations

People attend to cues that convey information about social norms and try to comply with norms they believe are in force. Dispositions to comply with social norms are universal, suggesting that adherence to such norms is selectively advantageous. Possibly, compliance with social norms, however arbitrary these may be, serves a signaling function and is used to control attributions affecting fitness. To begin to test this hypothesis, we performed several experiments in which subjects watched videotapes of models violating everyday social norms and then rated those models on dimensions that would be relevant to the models' fitness, if subjects and models were socially interacting. In some experiments, violations of minor social norms significantly altered such ratings. Even subjects who failed to cite norm violations when given the opportunity nonetheless gave lower ratings to models as the result of norm violations. A manipulation that increased the salience of such norms increased the adverse effects of norms violations. The results are consistent with the hypothesis that norm compliance serves an important signaling function.     

Functions of p21Waf1 in norm and in stress

Cyclin-dependent kinase inhibitor p2(Waf1/Cip1/Sdi1/CAP20) plays the key part in cell cycle arrest at the G1/S checkpoint in response to DNA damage, and is involved in the assembly of active cyclin-kinase complexes, in particular, cyclin D-Cdk4/6. Recent studies extended the range of known p21Waf1 functions. In addition to the cell-cycle control, p21Waf1 participates in important cell processes such as differentiation, senescence, and apoptosis. A balance of p21Waf1 functional activity seems to shift depending on the cell state (senescence, exposure to stress, expression of viral oncogenes). This is due to direct or indirect interaction with various modulators or to modification (phosphorylation, partial proteolysis) of p21Waf1. The review considers the structure of p21Waf1, its posttranslational modification, interactions with various cell or viral proteins, and their effects on the p21Waf1 function and the cell.