Optional tool use: The case of wild bearded capuchins (Sapajus libidinosus) cracking cashew nuts by biting or by using percussors

Tool use in humans can be optional, that is, the same person can use different tools or no tool to achieve a given goal. Strategies to reach the same goal may differ across individuals and cultures and at the intra‐individual level. This is the first experimental study at the intra‐individual level on the optional use of a tool in wild nonhuman primates. We investigated optional tool use by wild bearded capuchins (Sapajus libidinosus) of Fazenda Boa Vista (FBV; Piauí, Brazil). These monkeys habitually succeed in cracking open the mesocarp of dry cashew nuts (Anacardium spp.) by pounding them with stones and/or by biting. We assessed whether availability of a stone and resistance of the nut affected capuchins' choice to pound or to bite the nuts and their rates of success. Sixteen capuchins (1–16 years) received small and large dry cashew nuts by an anvil together with a stone (Stone condition) or without a stone (No‐Stone condition). In the Stone conditions, subjects used it to crack the nut in 89.1% (large nuts) and 90.1% (small nut) of the trials. Nut size significantly affected the number of strikes used to open it. Availability of the stone significantly increased the average percent of success. In the No‐Stone conditions, monkeys searched for and used other percussors to crack the nuts in 54% of trials. In all conditions, age affects percentage of success and number of strikes to reach success. We argue that exclusive use of stones in other sites may be due to the higher abundance of stones at these sites compared with FBV. Since capuchins opened cashews with a tool 1–2 years earlier than they succeed at cracking more resistant palm nuts, we suggest that success at opening cashew nuts with percussors may support the monkeys' persistent efforts to crack palm nuts.     

Subunit composition of a high molecular weight oligomer: Limulus polyphemus hemocyanin

The hemocyanin of Limulus polyphemus is a 48-subunit aggregate. This 3.3 × 10⁶-dalton oligomer is composed of structurally and functionally heterogeneous subunits. Using polyacrylamide electrophoresis J. Markl, A. Markl, W. Schartau, and B. Linzen (J. Comp. Physiol. Ser. B130,283–292, 1979) observed 12 bands; while using immunoelectrophoresis, M. Hoylaerts, G. Preaux, R. Witters, and R. Lontie (Arch. Int. Physiol. Biochem.87, 417–418, 1979) and J. Lamy, J. Lamy, J. Weill, J. Bonaventura, C. Bonaventura, and M. Brenowitz. (Arch. Biochem. Biophys.196, 324–339, 1979) observed 8 subunits. To proceed with an analysis of subunit roles in assembly it is first necessary to determine the number of distinct subunits. Refinement of the chromatographic separation procedures has led to the isolation of 8 immunologically distinct subunits as well as additional charge isomers which cannot be distinguished immunologically. Alkaline electrophoresis revealed 15 bands and isoelectric focusing up to 17. On the basis of extensive control experiments, including composit acrylamide-agarose immunoelectrophoresis and checks for conformational isomers, aggregation, proteolysis, and other types of degradation, we conclude that the electrophoretic heterogeneity of immunologically identical subunits is not artifactual. We have extended the nomenclature used by Lamy et al. (1979) to include the electrophoretic heterogeneity by using primes (′) to denote electrophoretically distinguishable subunits which are immunologically identical. A number of patterns have become apparent by correlating the results obtained by the different techniques. For example, immunologically pure subunit II, which shows 3 bands on alkaline electrophoresis, is in fact a mixture of electrophoretically distinct subunits II, II′, II″. Except for subunits II, II′, and II″ immunoelectrophoretically identical subunits are typically homogeneous on sodium dodecyl sulfate-gels. However, slight differences in the apparent molecular weight are observed on high-resolution gels between immunologically unrelated subunits. The immunological identity and electrophoretic differences suggest that the charge isomers which are immunologically identical have similar antigenic surfaces. If a charge substitution is not in a critical location, we would expect the electrophoretically distinct but immunologically identical subunits to have identical assembly roles. Comparison of the results for Limulus hemocyanin with the hemocyanin of related species Eurypelma californicum and Androctanus australis, which have 7 and 8 immunologically distinct subunits, respectively, suggests that the calcium-mediated aggregation from 24 to 48 subunits of Limulus does not require more extensive subunit complexity.     

Genetic and molecular mapping of the pma1 mutation conferring vanadate resistance to the plasma membrane ATPase from Saccharomyces cerevisiae

Summary In the yeast Saccharomyces cerevisiae, the pma1 mutations confers vanadate-resistance to H⁺-ATPase activity when measured in isolated plasma membranes. In vivo, the growth of pma1 mutants is resistant to Dio-9, ethidium bromide and guanidine derivatives. This phenotype was used to man the pma1 mutation adjacent to LEU1 gene on chromosome VII. From a cosmid library of a wild-type Saccharomyces cerevisiae genome, a large 30 kb DNA fragment was isolated by complementation of a leu1-pma1 double mutant. A 5 kb HindIII fragment was subcloned and it restored both Leu⁺ and Pma⁺ phenotypes after integrative transformation. The restriction map of the 5 kb HindIII fragment and Southern blot analysis reveal that the cloned fragment contains the entire structural gene for the plasma membrane ATPase and the 5 end of the adjacent LEU1 gene. The pma1 mutation conferring vanadate-resistance is thus located in the structural gene for the plasma membrane ATPase.Publication n^o 2456 from the Biology Directorate of the Commission of European Communities     

Tool use in capuchin monkeys: Distinguishing between performing and understanding

A horizontal plexiglas tube containing a food-reward was presented to four naive tufted capuchins and suitable sticks were provided to push the reward out. Three monkeys out of four spontaneously used the tools and showed very different styles of solving the task. In more complex conditions, in which the sticks needed to be combined or actively modified in order to become effective, the monkeys were always successful; however, their performance was loaded with errors which did not disappear throughout the trials. Evidence of a difference between success in solving the problem and its understanding was found. This suggests that although capuchins can discover new means through active experimentation, they do not mentally represent the characteristics necessary for a tool to be effective, nor do they modify the tool appropriately beforehand. At this level, a major difference with chimpanzees emerges.     

Growth,ammonia accumulation and glutamine synthetase activity in alfalfa (Medicago sativa L.) shoots and cell cultures treated with phosphinothricin

Summary Phosphinothricin is a non-selective herbicide which inhibits glutamine synthetase (EC 6.3.1.2) activity causing an overaccumulation of ammonia in higher plants. Alfalfa (Medicago sativa L) shoot tissue and petiole-derived callus exposed to phosphinothricin show 50 and 70% reductions, respectively, in glutamine synthetase activity with a concomitant rise of 10 and 20 fold, respectively, in endogenous ammonia. The diffusibility of ammonia may limit the use of a detoxifying gene, phosphinothricin acetyltransferase, as a selectable marker for alfalfa transformation. However, the addition of up to 40 times the standard levels of ammonium nitrate to the culture media used in this study had no effect on callus growth, although glutamine synthetase activity was inhibited by 50% and endogenous ammonia increased 27 fold. Therefore, ammonia accumulation may not be the primary cause of cell death in alfalfa after exposure to phosphinothricin. It follows that diffusion of ammonia from cell to cell would not restrict the selection for phosphinothricin acetyltransferase transformed cells, thereby indicating that this enzyme could be used as a selectable marker in transformation experiments.Abbreviations PPT Phosphinothricin - PAT Phosphinothricin acetyltransferase     

Coated nuts as an enrichment device to elicit tool use in tufted capuchins (Cebus apella)

The present paper describes a simple technique that hardens the shell of nuts and makes the use of a tool to crack them open more compelling. Walnuts were coated with a dough of sawdust and nontoxic white glue in different combinations; they were tested for hardness by using machines normally used to test different kinds of wood. Data on relative hardness for uncoated walnuts and walnuts coated with dough of two different combinations are presented. The coated walnuts were significantly harder to break than the uncoated ones, whereas no significant difference was found when comparing the hardness of two types of coated walnuts. Furthermore, observations on a captive group of tufted capuchins (Cebus apella) are described. The monkeys needed significantly more time to break open the coated walnuts. Early results show that coated walnuts may favor acquistion of tool use skills in a juvenile capuchin.     

Allometric shape change and heterochrony in the freeliving coral Trachyphyllia bilobata (Duncan)

Regression analysis has been used to study the relationship between age, size, shape, and surface area in two ancestral-descendant populations of the Neogene Caribbean coral Trachyphyllia bilobata. Analyses of the relationship between size and age show that the relationship is isometric and that little difference occurs between populations in mean corallite length or height and in their rates of growth. Onset of columella growth is significantly earlier, however, in the descendant population. Studies of the relationship between size and shape show that growth is allometric, with shape change occurring in both corallum elongation and pinching of the corallite wall during ontogeny. In the descendant population, pinching and elongation initiate earlier in the ontogeny of the coral. These results suggest that the evolutionary development of the meandroid form in freeliving corals has been accomplished by heterochrony, involving a complex set of disassociated peramorphic changes in ontogeny accompanied by paedomorphic changes in astogeny. Further analyses show that the observed heterochronic changes serve to decrease corallum surface area which may in turn enhance sediment removal and nutrition in unstable habitats.     

Suitability of a rapid gas chromatographic method for total mesophilic bacteria and coliform enumeration in hamburgers

An instrumental method for the rapid determination of total mesophilic bacteria and total coliforms in hamburgers is described. The two procedures are based on the gas chromatographic determination of metabolic CO₂ in equilibrium in the head space of sealed vials containing suitable media and inoculated with aliquots of the sample under examination. Both procedures proved to be suitable for quality control of meat products, being highly sensitive, reproducible, simple and rapid. Good correlation coefficients were obtained with plate counting for microbial concentrations ranging between 10¹ and 10⁸.