The ontogeny of social relationships with group companions among free-ranging infant rhesus monkeys I. Social networks and differentiation

Social networks of infant rhesus monkeys (Macaca mulatta) in a free-ranging, lineage-based group on Cayo Santiago are described by assessing the extent to which four measures of positive interaction between infants and finely-divided categories of companions are associated with (1) degree of relatedness through maternal lines; (2) sex of the companion; (3) age of the companion; and (4) dominance rank of the infant's lineage. The results suggest that the infant's social network mirrors that of its mother both in the first weeks of life and as late as 30 weeks of age. Infants have more positive social interaction with close kin than with distant kin or with unrelated individuals, and thus function as members of their lineage from the beginning. They associate more with female companions than with male companions, and more with younger immatures than with older immatures. Finally, infants in the top-ranking lineage spend more time with their own relatives than do infants in other lineages. The fact that these patterns change little as the infant gains independence from the mother supports suggestions that early maternal influence serves to pass on aspects of the mother's social network. It is suggested that the ontogeny of early social relationships resembles a process of differentiation.     

Mutagenesis by 4-nitrobenzofurazans and furoxans.

15 nitrobenzofurazans and 10 nitrobenzofuroxans synthesized primarily for testing as potential anti-rheumatic drugs were also tested for mutagenicity in Salmonella typhimurium strains TA98 and TA100. The method used involved placing each compound in a "well" cut out of a plate of selective medium previously seeded with the appropriate tester strain, and then adding a rat liver microsome/cofactor mixture to one of the two wells on each plate. This method is considerably cheaper and more convenient than the conventional agar overlay technique, but in the present series of experiments failed to detect 4 compounds which could be detected by the overlay technique. Using a combination of the two techniques, 21 of the 25 compounds tested were found to be mutagenic. All 10 benzofuroxans and 9 of the 15 benzofurazans were detected as direct-acting mutagens with at least one of the two tester strains. Two of the benzofurazans gave positive results only in the presence of rat liver microsomes, and hence are pro-mutagens. One of the 4 benzofurazans which gave negative results for mutagenicity in these tests was found to be an efficient inhibitor of a neutral protease activity found in rheumatic synovial fluid, and may therefore have some potential as an anti-rheumatic drug.     

Conditions for the various types of co-operativity allowed by the adair,equation and their relation with the algebraic character of binding polynomials

A convenient way to obtain for any number, n, of sites, the functions of the constants of the Adair equation that decide the type of co-operativity of ligand binding to a non-dissociating protein is given and is illustrated by the examples n = 4 and n = 5. These functions are invariants of the binding polynomial and various of its derivatives.Although there are some simple sufficient conditions (inequalities relating successive Adair constants) for some co-operativity types, the full necessary and sufficient conditions even for uniform positive and negative co-operativity depend on very complicated functions of the constants for n > 4.However there are alternative ways of writing binding polynomials known as canonical forms. Up to at least n = 5, and probably beyond, the conditions that are complicated in terms of Adair constants are very simple in terms of the constants of canonical forms. For instance any fourth-degree polynomial can be written in the form p(x - α)⁴ + q(x - β)⁴ + 6μ (x - α)²(x - β)² although in three different ways. For one of these ways, the sign of μ distinguishes between mixed and uniform co-operativity. For any kind of mixed co-operativity μ > 0, while μ < 0 corresponds to uniform co-operativity. Advantages of the use of canonical forms are briefly commented on.     

A favourable assessment of the O.P.T.--histamine reaction in the method of von Redlich and Glick

During the course of an investigation of the properties of triglyceride lipase in nerve endings of the central nervous system (1) there arose a need for rapid determinations of a lipase in a large number of membrane preparations. This communication reports a procedure for the determination of glyceride lipase in which fatty acid, formed from a radioactive substrate by the lipase, is separated from glycerides on DEAE-cellulose paper.     

Analyzing the joint effects of two antibodies and the design of molecularly engineered vaccines

A new analytical approach to determine how antibodies relate to each other in producing immunity is presented. One purpose of this analysis is to decide on the antigenic composition of vaccines. Regression analyses and single discrete analyses are shown to be inappropriate to this task. The proposed analyses makes multiple cut points on two pre-exposure antibody levels. At each resulting discrete classification, additive and multiplicative interaction parameters are calculated. Various models of joint antibody action are shown to produce two general patterns of interaction terms with this type of analysis. One pattern characterizes situations where each antibody, or something substituting for the action of each antibody, is always needed to eliminate all infections. This may be because the antigens to which the antibodies are directed are on separate microbes or because microbes can only be neutralized by the joint action of both antibodies. A second pattern characterizes situations where both antibodies act cooperatively but given high enough levels only one may be needed. This may be because the antibodies have the same molecular effect or because they act by separate means against the same organisms in an innoculum.     

Limiting nutrient patchiness and its rôle in phytoplankton ecology

Limiting nutrient patchiness is examined as a factor affecting the community structure and species succession of natural phytoplankton communities held in ammonia limited continuous culture at a dilution rate of 0.3 day^?1. It was found that under a homogeneous distribution of the limiting nutrient members of genus Chaetoceros dominated and when ammonia was added daily (patchy distribution), Skeletonema dominated. Intermediate patchiness gave rise to an assemblage dominated by both Chaetoceros and Skeletonema. The nutrient uptake ability of each assemblage was determined three weeks after experiment initiation. Each assemblage was best able to optimize uptake of ammonia under its particular patchy nutrient regime. Optimization of a patchy environment took place by an increased maximal uptake rate (V_max) while optimization of a homogeneous environment appeared to take place by increased substrate affinity (i.e., low K_s).This study demonstrates that limiting nutrient patchiness can alter the relative abundance of populations within a community based on each population's ability to exploit the limiting resource under a particular degree of patchiness. We also show that coexistence of two populations might be expected due to the patchiness of a single limiting nutrient. The importance of patchiness in relation to other factors which determine community structure is discussed.     

Protein symmetry and the co-operative ligand-binding behaviour predicted by allosteric Koshland models

It is shown that the nearest-neighbour interaction two-conformation allosteric models of Koshland, Nemethy & Filmer (1966) predict binding curves with a centre of symmetry when the protein is also symmetrical and induced-fit is assumed. When nonexclusive binding to both conformations is assumed, the models predict that the family of homotropic binding curves obtained by varying the heterotropic ligand has a centre of symmetry. It is argued that the symmetry or asymmetry of binding curves is the main experimentally verifiable prediction of allosteric models insofar as they are models of interaction between protein subunits.Symmetry in a binding curve greatly simplifies the analysis of cooperative behaviour. The co-operative features possible with a symmetric binding curve for a four-site protein are analysed. The sign of co-operativity may either be uniform or change twice as saturation increases; the conditions for the various possibilities are given. For example, in terms of the intrinsic binding constants per site A^∥₁, A2, etc. the necessary and sufficient condition for positive macroscopic co-operativity over the whole symmetric binding curve is A^∥₁≤ A2, A ^∥₁ ≤ A3 which should be contrasted with the obvious A^∥₁ ≤ Al, AZ ≤A^∥₃ (positive microscopic co-operativity) which is only a sufficient but not a necessary condition. A symmetric curve may have one or three, but no more, extrema of the “Hill coefficient” h. For three extrema a change of sign of microscopic (but not necessarily macroscopic) co-operativity is necessary but not sufficient. In the case where there are off-centre maxima of h, then h < 2 everywhere on the curve.The Koshland models predict qualitative and quantitative restrictions on the forms of binding curves additional to that of symmetry. In tetrameric induced fit models, negative co-operativity in the mid-region of the curve and positive co-operativity in the outside regions is possible, but not the opposite, and three extrema of h are possible with uniform positive but not with uniform negative co-operativity.Thus by recognising the importance of symmetry it has been possible to describe and categorise all the co-operativity behaviour possible with the most plausible Koshland tetrameric models. Several experimental examples of probable non-exclusive binding to proteins and enzymes are discussed, and it is shown how the symmetry point of view illuminates their interpretation.     

Neonatal heart rate variability and its relation to respiration

The heart rate and respiration signals from nine healthy full term neonates were studied using autoregressive spectral analysis and cross-correlation techniques. The heart rate spectra could be divided into three regions of activity: a very low frequency (VLF) region from 0-0.04 Hz; a low frequency (LF) band from 0.04-0.20 Hz; and a high frequency (HF) region above 0.20 Hz. The newborns exhibited very little respiratory sinus arrhythmia in their heart rate variability in contrast to the situation for adults and older infants. However, variations in heart rate correlated strongly with changes in the breath amplitude, leading to what may be termed a breath amplitude sinus arrhythmia. The neonatal heart rate behaviour under stable conditions of oscillation could be simulated with a nonlinear control model provided the delay time in the baroreceptor loop of the model was taken to be approximately 2 seconds longer than in adults. This is consistent with the immature neurological status of neonates.     

Rapid group separations of nucleotides and related compounds on silica columns

Nucleosides, bases, and nucleotides can be separated from one another rapidly (10–15 min) on 1-ml silica cartridges. Samples adjusted to 4 mm ammonium borate, 90% acetonitrile are loaded onto 1-ml columns equilibrated with the same solvent. Bases do not absorb to the silica under these conditions. Nucleosides are eluted with 16 ml of 0.5 m acetic acid in 90% acetonitrile. Nucleotides are then eluted with water. The 1-ml silica columns have performed well with samples up to 10 ml in volume. We have found the procedure to be quantitative and the gels to have high capacity (61 μmol Cyd/ml silica). Acid extracts from a large number of cells (10⁸) have been processed on a single cartridge.     

Affiliation and reciprocity in sibling and peer relationships among free-ranging immature male rhesus monkeys

The social relationships of immature male rhesus monkeys (Macaca mulatta) were studied during 1977, 1978 and 1981 at the Cayo Santiago colony, Puerto Rico. Three types of social relationship were selected for comparison: the sibling relationship, the strong peer relationship and the weak peer relationship. Sibling relationships were initially distinguished from peer relationships on the basis of individual characteristics (age and relatedness), whereas the two types of peer relationship were initially differentiated on the basis of criteria that concerned their structure. Although the three types of relationship showed certain similarities these were far outweighed by differences in the content, diversity, qualities and the relative frequency and patterning of their interactions, and the degree to which their interactions were characterized as reciprocal or complementary. These findings are discussed in relation to a number of questions concerning the sturucture of relationships and it is concluded that, in broad terms, the three types of relationship can be contrasted in terms of a multidimensional quality, their degree of affiliation.     

Effects of freeze-preservation on some pollen enzymes: II. Freezing and freeze-drying stresses

The isozymes of lily and corn pollen esterases and acid phosphatase were studied in relation to freeze-drying and vacuum-drying. Fresh samples of Lilium longiflorum L. and Zea mays L. pollen were frozen at rates ranging between 200 and 100 °C/min and freeze-dried at temperatures from 0 to ?70 °C for approximately 48 to 70 hr. Freeze-dried samples were rehydrated slowly (10% relative humidity) and rapidly (90% relative humidity). Vacuum-drying was performed at room temperature (22 °C).Soluble pollen enzymes were analyzed by disc electrophoresis on polyacrylamide gels stained with substrate specific reagents. The stained gels were evaluated by densitometry for migration rate, isozyme pattern, and relative activity. The numerical data generated in this manner were then statistically analyzed.The following conclusions resulted from this study: (i) freeze-drying and freeze-thawing treatments were comparable except for corn esterases; (ii) freeze-drying induced alterations in enzyme activity except for corn acid phosphatase; (iii) the freezing rate, the final freezing temperature, and exposure to various relative humidities produced few changes in freeze-dried material; (iv) freeze-drying was less detrimental than vacuum-drying to the enzyme characteristics of corn; (v) freeze-drying yielded higher viabilities than vacuum-drying; and (vi) acid phosphatase alterations appeared to be related to pollen viability in most cases.     

Mother-infant relationships among free-ranging rhesus monkeys on Cayo Santiago: A comparison with captive pairs

The general course of mother-infant relationships among free-ranging rhesus monkeys (Macaca mulatta) on Cayo Santiago is remarkably similar both qualitatively and quantitatively to that observed in the socially living captive colony at the MRC Unit at Madingley, England. Nevertheless, small but consistent differences appear to be due to differences between mothers in the two environments rather than differences between infants. Captive mothers may be described as more protective and less encouraging of early independence in their infants than free-ranging mothers. Moreover, captive pairs have become more like free-ranging pairs over the years, perhaps as captive mothers have been allowed to raise their infants in the presence of kin. A unitary concept of environmental complexity is not useful in accounting for the results.     

Human Y-chromatin : III. The nucleolus

The relative positions of nucleoli and the Y-chromatin body were investigated in human interphase fibroblast nuclei to determine if the reported nucleolar association of the Y-body might be a chance phenomenon. Although nucleolar material was found to be mainly in the central area of the nucleus, the association of the Y-body with a nucleolus was highly significant, irrespective of the morphology or location of the Y-body within the nucleus. The association was corroborated with late interphase and early prophase nuclei in which nucleolar remnants were seen to concentrate around the Y chromosome.     

Biosynthesis of 2-methylalkanes in the crickets Nemobius fasciatus and Gryllus pennsylvanicus.

The biosynthesis of 2-methylalkanes was studied in the crickets $\text{Nemobius}\text{fasciatus}$ and $\text{Gryllus}\text{pennsylvanicus}$. Labelled acetate, valine, and isobutyric acid were incorporated into the cuticular hydrocarbon of $\text{N.}\text{fasciatus}$ at levels of 6.0 ± 1, 6.5 ± 2, and 1.5 ± 0.7 percent respectively. The hydrocarbons of this insect are 20 percent 2-methylalkanes, primarily of even numbered carbon chain lengths, and 80% n-alkanes. Of the label incorporated into the hydrocarbon fraction, 28 ± 2 percent of sodium [1-¹⁴C] acetate, 98 ± 1 percent of L-[G-³H] valine, and 75 ± 10 percent of [1-¹⁴C] isobutyric acid were incorporated into the 2-methylalkanes. This suggests that valine is converted to isobutyric acid and is incorporated into the even numbered carbon chain length 2-methylalkanes during the initial stages of chain elongation. Similar data obtained in $\text{G.}\text{pennsylvanicus}$ suggests that leucine is converted to isovaleric acid which is then incorporated into the odd numbered carbon chain length 2-methylalkanes.     

Relationships among adult females in captive vervet monkeys: Testing a model of rank-related attractiveness

Data from three captive groups of vervet monkeys (Cercopithecus aethiops sabaeus) were used to test predictions from Seyfarth's (1977) model of rank-related attractiveness. Grooming patterns among adult females were consistent with the model's predictions. There was also evidence that females compete for access to the alpha female, as would be predicted by the model. This study failed to provide evidence for reciprocal support in agonistic encounters based on proximity relationships, independent of kinship.     

Interactions of bovine fibrinogen and thrombin. Early events in the development of clot structure.

Interactions which determine the rate of conversion of fibrinogen into monomer fibrin and the retention of monomer fibrin in a noncompactible form through interaction with residual fibrinogen (solution stabilization) were examined through the kinetics of formation of equilibrium compactible network at pH 7 and ionic strength 0.15. For studies of conversion, reactions with thrombin were at 29 or 2 °C, hirudin was added at successive times to inhibit thrombin, and compactible network was equilibrated at 2 °C, where solution stabilization is negligible. A substrate dependency of initial rate is interpreted on the basis of inactive complex formation between thrombin and both fibrinogen and monomer fibrin. At 29 or 2 °C specific rate constants are 32 or 2.9 × 10⁶ liter/mol, and association constants for inactive complex formation are 5.2 or 2.0 × 10⁵ liter/mol. The second peptide-A is removed from fibrinogen ~ 40-fold as rapidly as the first.With equilibration at 29 °C, compactible network does not appear until the solution stabilization ratio of residual fibrinogen/monomer fibrin is four. Thereafter, increasing amounts of compactible network appear. However, the stabilization ratio progressively decreases to approximately two, a situation which indicates the complexity of the stabilization mechanism.The thrombin-hirudin association constant is estimated to be 4.9 or 17 × 10¹¹ liter/mol at 29 or 2 °C.     

The variability of some motor components of social play and agonistic behaviour in infant eastern coyotes, Canis latrans var

The duration and stereotypy (in terms of duration) of three actions, stand-overs (SO), generalbites (GB), And scruff-bites (SB), were measured during social play and agonistic interactions in infant eastern coyotes (Canis latrans). The rate of biting was also calculated. We found: (1) SO's and GB's lasted a significantly shorter time during play; (2) when performed during playful interactions, all three acts showed more stereotypy; (3) there was no significant difference between the rates of occurrence of biting during the two situations. A discussion of the 'exaggerated' nature of play behaviour is presented, particularly concerning the form of motor actions that are used during this activity.     

Wound healing in the cornea of the chick embryo: III. The influence of pore size of millipore filters on the migration of isolated epithelial sheets in culture

The migratory activity of epithelia isolated from the cornea and the dorsal skin of chick embryos of different ages was examined in vitro. Five types of Millipore filters differing in pore size served as models to represent degrees of unevenness of the substrate instead of the natural wound beds of the corneal stroma and the dorsal dermis. Migration of the epithelium was rapid and extensive when the pore size was below 0.8 μm, but was inhibited or stopped when the pore size reached or exceeded 0.8 μm. The effect of surface properties of the substratum on the motility of the cell membrane and thus on the movement of the cells is discussed.     

Membrane permeability and receptor function.

This paper presents a model of receptor function for receptors that mediate selective increases in ionic permeabilities (e.g. receptors that are sensitive to acetylcholine and gamma-aminobutyric acid). The model distinguishes itself from previous models by the qualitative and quantitative application of current biophysical approaches to ion permeation. Explicit consideration of receptor-controlled permeation sites and membrane permeability results in a specific and testable theory into which complex receptor phenomena can easily be incorporated.Examination of agonist concentration-conductance data from a well-studied GABAnergic receptor allows invalidation of a standard assumption for determining kinetic constants of agonist-receptor interactions. Specifically, calculations are presented which indicate that the size of an individual receptor (elementary) conductance event can vary with agonist concentration. The following section develops the expressions relating agonist concentration to total membrane conductance for possible receptor models which incorporate variations in the amplitude of elementary conductance events.In the case of desensitization, the “inactivated” receptor is suggested to result from occupation and inactivation, not at the agonist-binding (activation) site of the receptor, but at the ionophore. The ionophore occupation model provides a parsimonious explanation of different types of desensitization. In addition, incorporation of this model into the cyclic reaction model of Katz &; Thesleff (1957) provides increased specification for the cyclic model and results in new experimental predictions.