The kangaroo's tail propels and powers pentapedal locomotion

When moving slowly, kangaroos plant their tail on the ground in sequence with their front and hind legs. To determine the tail''s role in this ‘pentapedal’ gait, we measured the forces the tail exerts on the ground and calculated the mechanical power it generates. We found that the tail is responsible for as much propulsive force as the front and hind legs combined. It also generates almost exclusively positive mechanical power, performing as much mass-specific mechanical work as does a human leg during walking at the same speed. Kangaroos use their muscular tail to support, propel and power their pentapedal gait just like a leg.     

Understanding control of calcitic biomineralization—Proteomics to the rescue

The avian eggshell is one of the fastest calcifying processes known and represents a unique model for studying biomineralization. Eggshell strength is a crucial economic trait for table egg production, and ensures that a safe egg reaches the consumer kitchen. However, a common toolkit for eggshell mineralization has not yet been defined. In this issue, label‐free MS‐based protein quantification technology has been used by Sun et al. (Proteomics 2013, 13, 3523–3536) to detect differences in protein abundance between eggshell matrix from strong and weak eggs and between the corresponding uterine fluids bathing strong and weak eggs. Proteins associated with the formation of strong eggshells are identified, which are now candidates for further investigations to define the regulatory relationship between specific eggshell matrix proteins and calcite crystal texture.     

Probing the limits of the DNA breakage-reunion domain of the Escherichia coli DNA gyrase A protein.

In a previous report (Reece, R. J., and Maxwell, A. (1989) J. Biol. Chem. 264, 19648-19653) we showed that treatment of the Escherichia coli DNA gyrase A protein with trypsin generates two stable fragments. The N-terminal 64-kDa fragment supports DNA supercoiling, while the C-terminal 33-kDa fragment shows no enzymic activity. We proposed that the 64-kDa fragment represents the DNA breakage-reunion domain of the A protein. We have now engineered the gyrA gene such that the 64-kDa protein is generated as a gene product. The properties of this protein confirm the findings of the experiments with the 64-kDa tryptic fragment. We have also generated a series of deletions of the gyrA gene such that C-terminal and N-terminal truncated versions of the A protein are produced. The smallest of the N-terminal fragments found to be able to carry out the DNA breakage-reunion reaction is GyrA(1-523). The cleavage reaction mediated by this protein occurs with equal efficacy as that performed by the intact GyrA protein. Deletion of the N-terminal 6 amino acids from either the A protein or these deletion derivatives has no effect on enzymic activity, while deletion of the N-terminal 69 amino acids completely abolishes the DNA breakage-reunion reaction. Therefore the smallest GyrA protein we have found that will perform DNA breakage and reunion is GyrA(7-523). A model is proposed for the domain organization of the gyrase A protein.     

A simple in vivo assay for increased protein solubility.

Low solubility is a major stumbling block in the detailed structural and functional characterization of many proteins and isolated protein domains. The production of some proteins in a soluble form may only be possible through alteration of their sequences by mutagenesis. The feasibility of this approach has been demonstrated in a number of cases where amino acid substitutions were shown to increase protein solubility without altering structure or function. However, identifying residues to mutagenize to increase solubility is difficult, especially in the absence of structural knowledge. For this reason, we have developed a method by which soluble mutants of an insoluble protein can be easily distinguished in vivo in Escherichia coli. This method is based on our observation that cells expressing fusions of an insoluble protein to chloramphenicol acetyltransferase (CAT) exhibit decreased resistance to chloramphenicol compared to fusions with soluble proteins. We found that a soluble mutant of an insoluble protein fused to CAT could be selected by plating on high levels of chloramphenicol.     

Epilepsy and Driving

The status of the epileptic applicant for a licence to drive a private motor vehicle has changed from total prohibition through a stage of partial approval subject to medical assessment to the present conditional right to a driving licence. We report a study of a series of patients which shows that many and probably most epileptics have obtained driving licences by concealment of their condition, yet the new regulations continue to expect true declarations. It is suggested that, in common with applicants for a public service vehicle or a heavy goods vehicle driving licence, the applicant for a licence to drive a private motor vehicle should provide a medical report of fitness. The epileptic should be included in a general category of medically restricted drivers subject to individual medical assessment.