Characterization and phenotypic control of the cytochrome content of Escherichia coli

1. Electron-transport particles derived from Escherichia coli grown aerobically contain three b-type cytochromes with mid-point oxidation-reduction potentials at pH7 of +260mV, +80mV and -50mV, with n=1 for each. The variation of these values with pH was determined. 2. E. coli develops a different set of b-type cytochromes when grown anaerobically on glycerol with fumarate or nitrate as terminal electron acceptor. Electron-transport particles of fumarate-grown cells contain b-type cytochromes with mid-point potentials at pH7 of +140mV and +250mV (n=1). These two cytochromes are also present in cells grown with nitrate as terminal acceptor, where an additional cytochrome b with a mid-point potential of +10mV (n=1) is developed. 3. The wavelengths of the alpha-absorption-band maxima of the b-type cytochromes at 77K were: (a) for aerobically grown cells, cytochrome b (E(m7) +260mV), 556nm and 563nm, cytochrome b (E(m7) +80mV), 556nm and cytochrome b (E(m7)-50mV), 558nm; (b) for anaerobically grown cells, cytochrome b (E(m7) +250mV), 558nm, cytochrome b (E(m7) +40mV), 555nm and cytochrome b (E(m7) +10mV), 556nm. 4. Cytochrome d was found to have a mid-point potential at pH7 of +280mV (n=1). 5. Cytochrome a(1) was resolved as two components of equal magnitude with mid-point potentials of +260mV and +160mV (n=1). 6. Redox titrations performed in the presence of CO showed that one of the b-type cytochromes in the aerobically grown cultures was reduced, even at the upper limits of our range of electrode potentials (above +400mV). Cytochrome d was also not oxidizable in the presence of CO. Neither of the cytochromes a(1) was affected by the presence of CO.     

Seed coat variation in Glycine Willd. subgenus Glycine (Leguminosae) by SEM

Seed of the genusGlycine Willd. typically exhibits a muriculate appearance resulting from adherence to the true seed coat of the perisperm or inner pod wall layer. Thickened cell walls of the perisperm superimpose a reticulate network on the seed coat, the type of network ranging from alveolate to stellate depending on the shape of the perisperm cells. Tubercles distributed at intervals give the seed its roughened appearance. Seed lacking an attached perisperm appears smooth and shiny. Seed morphology of 62 collections representing the six species of the subgenusGlycine is examined in detail to elucidate inter-and intraspecific variability. Seed perisperm pattern appears to be characteristic for each species, but there are exceptions.Glycine canescens F. J. Herrn. andG. clandestina Willd. seeds possess a reticulate network and tubercles of irregular shape, the perisperm appearing granular inG. clandestina. Seeds ofG. latrobeana (Meissn.) Benth. andG. tabacina (Labill.) Benth. lack a distinct network and have stellate tubercles; the perisperm is granular inG. latrobeana and some plants ofG. tabacina. A few collections ofG. clandestina approachG. tabacina in seed appearance.Glycine tomentella Hayata seeds exhibit a regularly alveolate arrangement, while those ofG. falcata Benth. lack a perisperm layer altogether. Variation in seed coat within a species can usually be linked to differences in chromosome number or some aspect of gross morphology. Diploid collections ofG. tomentella (2n = 40) exhibit recognizable differences in seed morphology compared with tetraploids (2n = 80), coincident with other striking dissimilarities in gross morphology. An incompletely attached perisperm is accompanied by aneuploidy in severalG. tomentella accessions, while other 78 and 38 chromosome aneuploids produce normal seeds.     

The application of biomechanical motion analysis to aspects of green monkey (Cercopithecus a. sabaeus) locomotion

A cinematographic method of biomechanical motion analysis is presented which permits the determination of body segment forces and joint moments of force, and thereby dominant muscle action. An analysis of the horizontal leap of Cercopithecus is used as an example of the utility of this approach in the area of functional morphology. Kinematic and kinetic data are presented and discussed in terms of the biomechanical requirements of this form of locomotion. The importance of a consideration of inertial as well as gravitational forces in an analysis of positional behavior involving body motion is stressed.     

Secondary dispersal mechanisms of winged seeds: a review

Winged seeds, or samaras, are believed to promote the long‐distance dispersal and invasive potential of wind‐dispersed trees, but the full dispersive potential of these seeds has not been well characterised. Previous research on the ecology of winged seeds has largely focussed on the initial abscission and primary dispersal of the samara, despite it being known that the primary wind dispersal of samaras is often over short distances, with only rare escapes to longer distance dispersal. Secondary dispersal, or the movement of the seeds from the initial dispersal area to the site of germination, has been largely ignored despite offering a likely important mechanism for the dispersal of samaras to microhabitats suitable for establishment. Herein, we synthesise what is known on the predation and secondary dispersal of winged seeds by multiple dispersive vectors, highlighting gaps in knowledge and offering suggestions for future research. Both hydrochory and zoochory offer the chance for samaroid seeds to disperse over longer distances than anemochory alone, but the effects of the wing structure on these dispersal mechanisms have not been well characterised. Furthermore, although some studies have investigated secondary dispersal in samaroid species, such studies are scarce and only rarely track seeds from source to seedling. Future research must be directed to studying the secondary dispersal of samaras by various vectors, in order to elucidate fully the invasive and colonisation potential of samaroid trees.     

A review of phosphorus efficiency in wheat

More efficient utilization of phosphorus by wheat plants is needed to extend the useful life of the phosphate reserves in the world, to reduce the cost of producing crops, and to improve the value of the grain and the straw produced. In this paper definitions of efficient use of phosphorus by wheat are reviewed, genotypic variation in phosphorus efficiency is reported, some consequences of breeding for greater efficiency are discussed, and ways to select more efficient genotypes are suggested.     

Human kinesiology

This paper discusses kinesiological aspects of human locomotion in terms of the incomplete morphological adaptation of the body to current lifestyles. Modern instrumentation used for biomechanical analyses is outlined for the most part in the context of human running. Investigations of spatiotemporal and segmental measures by electronic walkways, photography, optoelectronics and angle-angle diagrams are referred to, as is electromyography and direct force measurement. Three commonly identifiable areas of applied kinesiological research, namely sport, industry and medicine, are considered with reference to the prevention, treatment and after-care of injuries whether received on the sporting field, in the work place, or in an automobile accident.