A biomechanical study of the relationship between running velocity and three-dimensional lumbosacral kinetics

Faster running is not performed with proportional increase in all joint torque/work exertions. Although previous studies have investigated lumbopelvic kinetics for a single velocity, it is unclear whether each lumbopelvic torque should increase for faster running. We examined the relationship between running velocity and lumbopelvic kinetics. We calculated the three-dimensional lumbosacral kinetics of 10 male sprinters during steady-state running on a temporary indoor running track at five target velocities: 3.0 (3.20 ± 0.16), 4.5 (4.38 ± 0.18), 6.0 (5.69 ± 0.47), 7.5 (7.30 ± 0.41), and maximal sprinting (9.27 ± 0.36 m/s). The lumbosacral axial rotation torque increased more markedly (from 0.37 ± 0.06 to 1.99 ± 0.46 Nm/kg) than the extension and lateral flexion torques. The increase in the axial rotation torque was larger above 7.30 m/s. Conversely, the extension and lateral flexion torques plateaued when running velocity increased above 7.30 m/s. Similar results were observed for mechanical work. The results indicate that faster running required larger lumbosacral axial rotation torque. Conversely, the extension and lateral flexion torques were relatively invariant to running velocity above 7 m/s, implying that faster running below 7 m/s might increase the biomechanical loads causing excessive pelvic posterior tilt and excessive pelvic drop which has the potential to cause pain/injury related to lumbopelvic extensors and lateral flexors, whereas these biomechanical loads might not relate with running velocity above 7 m/s.     

Cloning of the replication region on the bacteriocinogenic plasmid pRJ9 of Staphylococcus aureus

Abstract A 5.8-kb Cla I fragment of pRJ9, a bacteriocinogenic plasmid of Sphylococcus aureus , was cloned in the unique Cla I site of pRJ5. The recombinant plasmid obtained, pRJ23, failed to confer bacteriocin production and immunity to bacteriocin on host cells. The cloned fragment was shown to contain the complete replicon of pRJ9. Attempts to clone the 4.4-kb Cla I fragment of pRJ9 were unsuccessful, apparently due to the inactivation of the basic replicon of the cloning vector. Therefore, plasmid pRJ5 cut at its Cla I site appears to be a suitable vector for cloning replication regions of plasmids that cab replicate in S. aureus .     

The cellular pathway of photosynthate transfer in the developing wheat grain. II. A structural analysis and histochemical studies of the pathway from the crease phloem to the endosperm cavity

In the developing wheat grain, photosynthate is transferred longitudinally along the crease phloem and then laterally into the endosperm cavity through the crease vascular parenchyma, pigment strand and nucellar projection. In order to clarify this cellular pathway of photosynthate unloading, and hence the controlling mechanism of grain filling, the potential for symplastic and apoplastic transfer was examined through structural and histochemical studies on these tissue types. It was found that cells in the crease region from the phloem to the nucellar projection are interconnected by numerous plasmodesmata and have dense cytoplasm with abundant mitochondria. Histochemical studies confirmed that, at the stage of grain development studied, an apoplastic barrier exists in the cell walls of the pigment strand. This barrier is composed of lignin, phenolics and suberin. The potential capacity for symplastic transfer, determined by measuring plasmodesmatal frequencies and computing potential sucrose fluxes through these plasmodesmata, indicated that there is sufficient plasmodesmatal cross-sectional area to support symplastic unloading of photosynthate at the rate required for normal grain growth. The potential capacity for membrane transport of sucrose to the apoplast was assessed by measuring plasma membrane surface areas of the various cell types and computing potential plasma membrane fluxes of sucrose. These fluxes indicated that the combined plasma membrane surface areas of the sieve element–companion cell (se–cc) complexes, vascular parenchyma and pigment strand are not sufficient to allow sucrose transfer to the apoplast at the observed rates. In contrast, the wall ingrowths of the transfer cells in the nucellar projection amplify the membrane surface area up to 22-fold, supporting the observed rates of sucrose transfer into the endosperm cavity. We conclude that photosynthate moves via the symplast from the se–cc complexes to the nucellar projection transfer cells, from where it is transferred across the plasma membrane into the endosperm cavity. The apoplastic barrier in the pigment strand is considered to restrict solute movement to the symplast and block apoplastic solute exchange between maternal and embryonic tissues. The implications of this cellular pathway in relation to the control of photosynthate transfer in the developing grain are discussed.     

Divergence in germination traits among arctic and alpine populations of <Emphasis Type="Italic">Koenigia islandica</Emphasis>: light requirements

Light is known to regulate conservative germination strategies and the formation of seed banks. Although these strategies are crucial to survival in tundra environments—especially for annuals—light requirements for germination in arctic–alpine species are seldom investigated. Furthermore, environmental differences between arctic and alpine regions are expected to lead to evolutionary divergence among conspecific populations in seed germination strategies. In this study, we report important differences in germination light requirements among six arctic and alpine populations of the annual Koenigia islandica. Light had little effect on germination of the seeds from Iqaluit (Nunavut, Canada), Yukon (Canada), and Jasper (Alberta, Canada), whereas the seeds from the most severe climates, Svalbard (Norway) and Colorado (USA), had strong light requirements. Stratification of the seeds had little influence on their germination light requirements, with the exception of the population from Dovre (Norway), in which it induced a strong light requirement. Possible adaptive explanations and some implications of these observed germination patterns are discussed.     

Molecular phylogeny and systematics of Genista (Leguminosae) and related genera based on nucleotide sequences of nrDNA (ITS region) and cpDNA (trnL-trnF intergenic spacer)

Phylogenetic relationships of Genista and related genera (Teline, Chamaespartium, Pterospartum, Echinospartum, Ulex, Stauracanthus and Retama) were assessed by the analysis of sequences of the nrDNA internal transcribed spacer (ITS region), and the cpDNA trnL-trnF intergenic spacer. The tree obtained by combining both sets of data indicates the existence of three lines of diversification within Genista, that correspond to three subgenera: Genista, Phyllobotrys and Spartocarpus, however, each of these lineages encompass also species of the related genera Echinospartum, Teline, Retama, Chamaespartium, Pterospartum, Ulex, Stauracanthus. The molecular data do not support division of these subgenera into taxonomical units at the sectional level; only sections Genista and Spartocarpus are monophyletic groups. The sequences of both regions are also informative at the specific level, grouping morphologically related species (e.g. the G. cinerea aggregate). The molecular data have also helped to clarify the position of taxa whose relationships were not well established (e.g. G. valdes-bermejoi). The relationships of related genera that belong to the Genista lines of diversification have also been investigated. Echinospartum splits into two separate clades matching the separation of two ecological and caryological differentiated groups. Teline also forms two groups, both placed near to Genista subgenus Genista, but that separated from the main core of the group. Retama, morphologically well differentiated from Genista, is close to Genista subgenus Spartocarpus. Chamaespartium and Pterospartum do not form a monophyletic group. Chamaespartium is closer to Genista subgenus Genista, whereas Pterospartum stands close to: 1) Genista subgenus Spartocarpus (particularly, sect. Cephalospartum); and 2) the Ulex-Stauracanthus clade (a terminal derivative of Genista subgenus Spartocarpus). Cases of incongruence (e.g. Echinospartum, Chamaespartium, Teline) between the trees obtained from the two molecular markers, may be indicating hybridisation and/or introgression between different lines of Genisteae.     

Assessing regional sustainable development through an integration of nonlinear principal component analysis and Gram Schmidt orthogonalization

The regional sustainable development level (SDL), sustainability of regional development (SRD) and system coordination (SC) make up the triangular truss of regional sustainable development assessment, but it is debated how should traditional practice best weight and calculate the whole sustainable development system level. The Bohai Rim, covering three provinces and two municipalities in China, lies in a region that is sensitive to profound conflict between socioeconomic development and environment pollution in the process of sustainable development. Considering the defects of traditional models and the multidimensionality of regional sustainability issues, we proposed an integrated model of nonlinear principal component analysis and Gram Schmidt orthogonalization and presented a novel regional sustainable development assessment method and framework from three perspectives for the society–economy–environment system of the Bohai Rim region. The results show that: (a) the integration of nonlinear principal component analysis and Gram Schmidt orthogonalization can well remedy the defects of traditional methods and provide a more objective conceptual framework; (b) the sustainability of regional development and system coordination models graphically demonstrate the essence and connotation of a dynamic sustainable development system; (c) the empirical study demonstrated that the Bohai Rim region has experienced a distinct development period in which the SRD experienced a steady decline and the SDL and SC generally increased; (d) the coordination ability can be improved by a decline in the environmental sustainability, which reveals the importance of environment subsystem optimization; and (e) the weight distribution of variables demonstrates that the most significant factors affecting sustainable development are the indicators from the dimensions of people's standard of living, economic structure and environmental pollution. This study enriches the sustainable development assessment theory and methodology, and lays the foundation for further sustainable development research in the Bohai Rim region.