Comparison of the heavy chains of physiologically different myosins by isoelectric focusing

The technique of isoelectric focusing in polyacrylamide gels was used to determine whether differences could be distinguished between the heavy chains of myosin prepared from physiologically different muscles of chicken. The results of focusing a mixture of fast, slow, embryonic skeletal and cardiac myosin indicated that two different heavy chains only were resolved. In fast, slow and embryonic myosin these were present in approximately equal amounts but the chain with the more acidic isoelectric point was present in greater quantity in cardiac myosin.     

Mitochondrial phylogeography and population history of pine martens Martes martes compared with polecats Mustela putorius

The flora and fauna of Europe are linked by a common biogeographic history, most recently the Pleistocene glaciations that restricted the range of most species to southern refugial populations. Changes in population size and migration, as well as selection, have all left a signature on the genetic differentiation. Thus, three paradigms of postglacial recolonization have been described, inferred from the patterns of DNA differentiation. Yet some species, especially wide-ranging carnivores, exhibit little population structuring between the proposed refugia, although relatively few have been studied due to the difficulty of obtaining samples. Therefore, we investigated mitochondrial variation in pine martens, Martes martes, in order to understand the extent to which they were affected by glacial cycles, and compared the results with an analysis of sequences from polecats, Mustela putorius. A general lack of ancient lineages, and a mismatch distribution that is consistent with an expanding population, is evidence that the present-day M. martes and Mu. putorius in central and northern Europe colonized from a single European refugium following a recent glaciation. There has also been interspecific mitochondrial introgression between M. martes and the sable M. zibellina in Fennoscandia.     

Age differences in locomotion of two subtropical galaginae

The locomotor behaviour ofGalago senegalensis andG. crassicaudatus (Primates: Lorisidae) was quantified in an 11-month field study in the Northern Transvaal of South Africa. This paper assesses the distinction between the behaviour of adults, and that of infants at the age when they first began foraging independently, taking into account seasonal variations in adult behaviour. Infants of both species differ significantly from adults in the types of locomotion they use, postures, activity, support use, height of observation and tree use. While all these factors are inter-connected, it is concluded that infants exploit a quantitatively different part of the arboreal habitat from adults, because of factors such as locomotor maturation and gross body size. Dietary differences are also possible but the present study cannot establish or deny this possibility.     

The mechanical significance of the occlusal geometry of great ape molars in food breakdown

Analyses of dental function are an essential component of the study of human evolution. However, with few exceptions, they have utilized the traditional analogizing method of comparative anatomy, and have assumed rather than demonstrated that proposed adaptive characters confer a performance benefit. Since food reduction is a mechanical process, it is appropriate to measure performance using mechanical parameters, specifically the ability of a given morphology to induce failure in food particle by either of the two major regimes: crush and shear, corresponding to simple stresses (tensile and compressive) and shear stress, respectively. We apply finite elements stress analysis to model the relationship between the angulation of the intercuspal occlusal surfaces in a “puncture crushing” mode of mastication. On the basis of morphological data acquired from sectioned great ape molars, we have predicted the nature, magnitude and distribution of stress in a standard food particle by models representing each morphotype. Results indicate that the blunt-cusped molars ofHomo, the gradually-sloping supporting (buccal) cusps but high-angled guiding (lingual) cusps of the lower molars ofPan, and the high angled occlusal surfaces ofGorillaare all more likely to fracture small food particles by shear, while the gradually sloping occlusal surfaces ofPongomolars are more likely to break them down by “crush”. Mechanisms of food failure induced by molars ofPanandHomowill vary according to the orientation of the tooth–food contacting surfaces, which in turn will vary according to the size of the food particle. These genera may be able to break food down either by shear or by “crush”.     

Mode of formation of cholesta-5,7-dien-3β-ol from cholest-5-en-3β-ol by larvae of Calliphora erythrocephala

1. The conversion of cholest-5-en-3beta-ol (cholesterol) into cholesta-5,7-dien-3beta-ol by axenic Calliphora erythrocephala larvae was demonstrated. 2. The transformation is probably direct (Delta(5)-->Delta(5,7)) and does not involve a Delta(0) intermediate (Delta(5)-->Delta(0)-->Delta(7)--> Delta(5,7)). 3. Delta(7)-bond formation involves the stereospecific elimination of the 7beta hydrogen atom. 4. The relative amounts of free and esterified sterols were determined in larvae grown on cholesterol as sole sterol source and on 5alpha-cholestan-3beta-ol supplemented with minimal amounts of cholesterol. 5. The significance of the results is assessed in relation to the probable role of cholesta-5,7-dien-3beta-ol as an intermediate in the biosynthesis of ecdysones.     

Objective classification of scapular kinematics in participants with movement faults of the scapula on clinical assessment

The aim of this study was to assess the potential of employing a classification tool to objectively classify participants with clinically assessed movement faults (MFs) of the scapula. Six participants with a history of shoulder pain with MFs of the scapula and 12 healthy participants with no movement faults (NMFs) performed a flexion movement control test of the scapula, while scapular kinematic data were collected. Principal component scores and discrete kinematic variables were used as input into a classifier. Five out of the six participants with a history of pain were successfully classified as having scapular MFs with an accuracy of 72%. Variables related to the upward rotation of the scapula had the most influence on the classification. The results of the study demonstrate the potential of adopting a multivariate approach in objective classification of participants with altered scapular kinematics in pathological groups.