Mechanisms and development of self–other distinction in dyads and groups

This opinion piece offers a commentary on the four papers that address the theme of the development of self and other understanding with a view to highlighting the important contribution of developmental research to understanding of mechanisms of social cognition. We discuss potential mechanisms linking self–other distinction and empathy, implications for grouping motor, affective and cognitive domains under a single mechanism, applications of these accounts for joint action and finally consider self–other distinction in group versus dyadic settings.     

Some New Aspects of 2 × 2 Table Measures and Their Applications

The paper deals with the analysis of 2 × 2 table measures and describes several new possibilities for applying them. An estimate is given for HELLMICH's asymmetric K-measure and a possible extension of the contingency concept in a special 2×2 case is presented. The concept introduced and the recommended computer application of the 2×2 table measures is supported by new results obtained for the relationship between jaw joint pains and noises examined earlier by F. SCHMID and C. ZSCHEGE. With a larger number of observations the opportunity arises for a deeper analysis of this dental problem using path analysis. The plan of evaluation and the conncetion between the variables examined is illustrated by a path-diagram. The association tables determined on the basis of the (C) values introduced during the examination of jaw joint disturbances using association analysis draw attention to the special role of the left side of mastication. The paper raises ideas for further generalisations and indicates where further research is needed.     

Activation of fatty acids by non-glyoxysomal peroxisomes

Ethylene treatment (approx. 20 l ·1^-1 in air for 2 d) of tobacco (Nicotiana tabacum L. cv. Havana 425) plants markedly increases the endo--1,3-glucanase (EC 3.2.1.39) content of leaves. The antigenic form of the enzyme induced is the same one whose production is blocked by treating cultured cells with combinations of auxin (1.1 · 10^-5 M -naphthaleneacetic acid) and cytokinin (1.4 · 10^-6 M kinetin). Evidence is presented that cultured tobacco cells require ethylene for -1,3-glucanase accumulation: i) ethylene treatment increased the accumulation of \-1,3-glucanase in callus tissues >10 d after subculturing and in cell-suspension cultures; ii) callus tissues can produce ethylene; iii) conditions known to inhibit ethylene production (1 mM CoCl₂; 33° C treatment) or ethylene action (approx. 1.6 mmol · 1^-1 norbornadiene in air) inhibited -1,3-glucanase accumulation by callus tissues treated for 4 d following subculturing; and, these inhibitory effects were prevented by exogenous ethylene. Combinations of auxin and cytokinin blocked ethylene-induced accumulation of -1,3-glucanase by cell-suspension cultures. The results favor a model in which ethylene induces results favor a model in which ethylene induces 1,3-glucanase accumulation, and auxin and cytokinin inhibit this induction process.Abbreviations NAA -naphthaleneacetic acid - NDE norbornadiene     

Voltage-dependent depolarization of bacterial membranes and artificial lipid bilayers by the peptide antibiotic nisin

The peptide antibiotic nisin is shown to disrupt valinomycin-induced potassium diffusion potentials imposed on intact cells of Staphylococcus cohnii 22. Membrane depolarization occurred rapidly at high diffusion potentials while at low potentials nisin-induced depolarization was slower suggesting that nisin requires a membrane potential for activity. This assumption was proven in experiments with planar lipid bilayers (black lipid membranes). Macroscopic conductivity measurements indicated a voltage-dependent action of nisin. The potential must have a trans-negative orientation with respect to the addition of nisin (added to the cis-side) and a sufficient magnitude (ca. -100 mV). With intact cells the threshold potential was lower (-50 to -80 mV at pH 7.5 and below -50 mV at pH 5.5). Single channel recordings resolved transient multistate pores, strongly resembling those introduced by melittin into artificial bilayers. The pores had diameters in the range of 0.2–1 nm, and lifetimes of few to several hundred milliseconds. The results indicate that nisin has to be regarded as a membrane-depolarizing agent which acts in a voltage-dependent fashion.Abbreviations BLM Black lipid membranes - CCCP carbonyl cyanide m-chlorophenylhydrazone - DOPC dioleoyl phosphatidylcholine - PS phosphatidylserine - TPP⁺ tetraphenylphosphonium cation     

Relative ability of ovine follicle stimulating hormone and itsβ-subunit to generate antibodies having bioneutralization potential in nonhuman primates

The relative ability of ovine follicle stimulating hormone and itsβ-subunit, two potential candidates for male contraceptive vaccine, to generate antibodies in monkeys capable of bioneutralizing follicle stimulating hormone was assessed usingin vitro model systems. Antiserum against native ovine follicle stimulating hormone was found to be highly specific to the intact form with no cross-reactivity with either of the two subunits while the antiserum againstβ-subunit of follicle stimulating hormone could bind to theβ-subunit in its free form as well as when it is combined withα-subunit to form the intact hormone. Both antisera could block the binding of the hormone to the receptor if the hormone was preincubated with the antibody. However, the follicle stimulating hormoneβ-antisera could only inhibit the binding of the hormone partially (33% inhibition) if the antibody and receptor were mixed prior to the addition of the hormone, while antisera to the native follicle stimulating hormone could block the binding completely (100% inhibition) in the same experiment. Similarly antisera to the native follicle stimulating hormone was significantly effective in blocking (100%) response to follicle stimulating hormone but not theβ-subunit antisera (0%) as checked using anin vitro granulosa cell system. Thus the probability of obtaining antibodies of greater bioneutralization potential is much higher if intact hormone is used as an antigen rather than itsβ-subunit as a vaccine. Majority of the work reported here was carried out during the tenure of Visiting Scientist fellowship awarded by the MRC Canada to the first author.     

Breakdown of crystalline cellulose by synergistic action between cellulase components from Clostridium thermocellum and Trichoderma koningii

Abstract Certain isolated components of fungal cellulases, which cannot effect the breakdown of highly ordered cellulose individually, interact together synergistically to do so when recombined. Suprisingly, not all fungal cellulase components exhibit this property, and no such synergism has been observed so far between fungal and bacterial cellulases.
The cellulase complex of Clostridium thermocellum cannot effect the extensive breakdown of highly ordered cellulose unless Ca²⁺ and dithiothreitol (DTT) are present. However, we now report that isolated cellobiohydrolase from Trichoderma koningii can combine with C. thermocellum cellulase to effect the breakdown of cellulose in the absence of Ca²⁺ and DTT. enhanced activity is observed if Ca²⁺ and DTT are present.
This finding may have important applications in industry: it certainly has important implications for those interested in the basic mechanism of cellulase action in C. thermocellum .     

Control of hypocotyl phototropism by phytochrome in a dicotyledonous seedling (Sesamum indicum L.)

Abstract The phototropic response in stems of higher plants is brought about by blue/UV light. The problem studied here is to what extent long-wavelength light, which is absorbed by phytochrome, affects the phototropic response. A refined measurement of phototropism — a curvature index — was applied to the hypocotyl of the sesame seedling (Sesamum indicum L.). The time course of the phototropic response was followed in continuous unilateral weak blue light (B, 460 nm, 8 mW m^?2). Long term red light (R) pretreatments, operating through phytochrome, strongly increase the rate and extent of the phototropic response once it is elicited by unilateral B, while the pretreatments decrease the sensitivity towards B. If a R pulse is given immediately prior to the onset of unilateral B, the rate of the response is strongly reduced compared to the time course of curvature observed when the pretreatment was terminated with a long wavelength far-red light (FR) pulse. R and FR were then applied simultaneously with unilateral B to manipulate the status of the phytochrome system during actual curvature. It was found that a low Pfr/P ratio (established by FR) stimulates the phototropic response far above the control (B alone), while a high Pfr/P ratio (established by R) reduces the response below the control. During bending a positive effect of phytochrome on the rate and extent of the phototropic response, which is saturated at a low level of Pfr, appears to be counteracted by an inhibitory effect which dominates at higher levels of Pfr, such as established by omnilateral R. However, if R is applied unilaterally from the same direction as B, R increases the rate of curvature. Apparently the sesame seedling is capable of detecting the direction of R relative to the direction of B. While a mechanistic explanation of these effects cannot be advanced at present, it is clear that the seedling is capable of super-imposing information about the actual light conditions during bending on a ‘memory’ of the light conditions prior to the onset of bending. Thus, the previous as well as the actual light conditions determine its phototropic responsiveness.     

Anatomy of the hominoid wrist joint: Its evolutionary and functional implications

Observations on the behavior of living hominoids show generic differences in the use and posture of the wrist joint. Both orang-utans and hylobatids usually use the wrist in suspensory behaviors. However, orang-utans emphasize markedly adducted and flexed wrist postures, while hylobatids emphasize violent forearm and wrist rotation. African apes, especially the gorilla, use the wrist more frequently than other hominoids for terrestrial quadrupedal weight-bearing. Humans use the wrist less frequently for supportive purposes than do other hominoids. These behavioral differences correspond to structural specializations in the proximal carpal joint of each of the hominoid genera. Although each of the hominoid genera has apparently modified its proximal carpal joint best to serve its characteristic behaviors, all hominoids share a unique proximal carpal joint that permits approximately 160ℴ of forearm rotation. The hylobatid proximal carpal joint is specialized in exhibiting a marked development of those structures limiting forearm rotation, but it is in most respects the least derived— that is, closest to the nonhominoid anthropoids. Chimpanzees show a proximal carpal joint that is more generalized than those of the other great apes but more derived than that of hylobatids. The human and gorilla proximal wrist joints, on the other hand, show marked modifications for weight-bearing in terrestrial behaviors. Orang-utans have the most derived proximal carpal joint, which in many respects parallels that of the slow-climbing nonhominoid primates. The comparative anatomy and structural specializations of the wrist joint support (a) an early divergence of hylobatids from the common hominoid stock, (b) a common ancestry for gorillas and humans separate from the other hominoids, and (c) a long independent evolutionary period for orang-utans since their divergence from the common hominoid stock, or one that was marked by strong selection pressures for wrist specializations. Unfortunately, the generalized condition of the chimpanzee’s wrist joint and the very derived condition of the orang-utan wrist provide uncertain evidence as to which of the two was first to diverge from the common hominoid stock. Identification of hominoid wrist specializations as reflecting real phylogenetic relationships or parallelisms depends on how well the phytogeny inferred from wrist morphology accords with those arrived at from the study of other systems.     

Blockade of potassium channels in the plasmalemma ofChara corallina by tetraethylammonium,Ba2+, Na+ and Cs+

Summary The outer membranes of plant cells contain channels which are highly selective for K⁺. In the giant-celled green algaChara corallina, K⁺ currents in the plasmalemma were measured during the action potential and when the cell was depolarized to the K⁺ equilibrium potential in high external K⁺ concentrations. Currents in both conditions were reduced by externally added tetraethylammonium (TEA⁺), Ba²⁺, Na⁺ and Cs⁺. In contrast to inhibition by TEA⁺, the latter three ions inhibited inward K⁺ current in a voltage-dependent manner, and reduced inward current more than outward. Ba²⁺ and Na⁺ also appeared to inhibit outward current in a strongly voltage-dependent manner. The blockade by Cs⁺ is studied in more detail in the following paper. TEA⁺ inhibited both inward and outward currents in a largely voltage-independent manner, with an apparentK _D of about 0.7 to 1.1mm, increasing with increasing external K⁺. All inhibitors reduced current towards a similar linear leak, suggesting an insensitivity of the background leak inChara to these various K⁺ channel inhibitors. The selectivity of the channel to various monovalent cations varied depending on the method of measurement, suggesting that ion movement through the K⁺-selective channel may not be independent.