Extraction and purification of tRNA from fruit tissues

Readily measurable yields of undamaged tRNA were obtained from tomato, pear and apple fruits by phenolic extraction at pH 8.8, removal of interfering alcohol insoluble substances by precipitation with 0·2 volumes of iso-PrOH and final purification by DEAE chromatography. Various other commonly used extraction and purification procedures were tested and found to be less effective. Active synthetases were isolated from acidic fruit tissues by adequate control of pH and maceration in the frozen state. After acylation with a radioactively labelled amino acid, fruit isoacceptor tRNA species were separated by reverse phase chromatography.     

On the competitive exclusion principle

The Competitive Exclusion Principle, formulated by V. Volterra (Memorie del R. Comitato Talassografico Italiano,131, 1–142, 1927) for a number of species competing for a common ecological niche, is extended to a number of species competing for many ecological niches. Supported by an N.I.H. training grant.     

A Vinyl Plastic Coating for Stained Thin Smears

Stained sections of bacteriological and hematological smears were covered with a 10% solution of a vinyl chloride polymer dissolved in methyl isobutyl ketone and observed, after drying, for periods up to 6 months. Visual properties of all preparations remained good over this period and no degeneration of the coating was observed. Some slight discoloration of the stock solution of plastic was noted after a few days exposure to light. Discoloration may be held in check by addition of 0.5% propylene oxide.     

Evolutionary Robotic Approaches in Primate Gait Analysis

Understanding how primates move is particularly challenging because many of the experimentation techniques that would normally be available are unsuitable for ethical and conservation reasons. We therefore need to develop techniques that can maximize the data available from minimally intrusive experimentation. One approach for achieving this is to use evolutionary robotic techniques to build a musculoskeletal simulation and generate movement patterns that optimize some global parameter such as economy or performance, or to match existing kinematic data. If the simulation has a sufficiently high biofidelity and can match experimentally measured performance criteria then we can use it to predict aspects of locomotor mechanics that would otherwise be impossible to measure. This approach is particularly valuable when studying fossil primates because it can be based entirely on morphology and can generate movements spontaneously. A major question in human evolution is the origin of bipedal running and the role of elastic energy storage. By using an evolutionary robotics model of humanoid running we can show that elastic storage is required for efficient, high-performance running. Elasticity allows both energy recovery to minimize total energy cost and also power amplification to allow high performance. The most important elastic energy store on the human hind limb is the Achilles tendon: a feature that is at best weakly expressed among the African great apes. By running simulations both with and without this structure we can demonstrate its importance, and we suggest that identification of the presence or otherwise of this tendon—perhaps by calcaneal morphology or Sharpey’s fibers—is essential for identifying when and where in the fossil record human style running originated.