Consistent scaling of whole-shoot respiration between Moso bamboo (Phyllostachys pubescens) and trees

Journal of Plant Research - Both Moso bamboo (Phyllostachys pubescens) and tree forests have a large biomass; they are considered to play an important role in ecosystem carbon budgets. The scaling...     

Heat shock proteins mediate trade‐offs between early‐life reproduction and late survival in Drosophila melanogaster

Ageing and the resulting increased likelihood mortality are the inescapable fate of organisms because selection pressures on genes that exert their function late in life is weak, promoting the evolution of genes that enhance early‐life reproductive performance at the same time as sacrificing late survival. Heat shock proteins (HSP) are known to buffer various environmental stresses and are also involved in protein homeostasis and longevity. The characteristics of genes for HSPs (hsp) imply that they affect various life‐history traits, which in turn affect longevity; however, little is known about the effects of hsp genes on life‐history traits and their interaction with longevity. In the present study, the effects of hsp genes on multiple fitness traits, such as locomotor activity, total fecundity, early fecundity and survival time, are investigated in Drosophila melanogaster Meigen using RNA interference (RNAi). In egg‐laying females, RNAi knockdown of six hsp genes (hsp22, hsp23, hsp67Ba, hsp67Bb, hsp67Bc and hsp27‐like) does not shorten survival but rather increases it. Knockdown of five of those genes on an individual basis reduces early‐life reproduction, suggesting that several hsp genes mediate the trade‐off between early reproduction and late survival. The data indicate a positive effect of hsp genes on early reproduction and also negative effects on survival time, supporting the antagonistic pleiotropic effects predicted by the optimality theory of ageing.     

Auxin-inducible protein depletion system in fission yeast

Background  

Inducible inactivation of a protein is a powerful approach for analysis of its function within cells. Fission yeast is a useful model for studying the fundamental mechanisms such as chromosome maintenance and cell cycle. However, previously published strategies for protein-depletion are successful only for some proteins in some specific conditions and still do not achieve efficient depletion to cause acute phenotypes such as immediate cell cycle arrest. The aim of this work was to construct a useful and powerful protein-depletion system in Shizosaccaromyces pombe.     

Post-error recruitment of frontal sensory cortical projections promotes attention in mice

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Caste-biased locomotor activities in isolated termites

Eusocial insects are characterized by a well-developed division of labour among castes. Although the successful division of labour should stem from behavioural differentiation depending on caste identity, caste-specific intrinsic behavioural characteristics might be masked by social interactions within colonies. The present study explores caste-specific intrinsic locomotive activities of termites by quantifying them in isolation. We track individual movement trajectories of the damp-wood termite Hodotermopsis sjostedti over 30 min and extract individual locomotion parameters. Multivariate statistical analyses reveal significant differences among castes: soldiers move more actively than workers and neotenic reproductives. The morphometric data of test individuals indicate that locomotor activities reflected caste identity more strongly compared with quantitative morphological variations among individuals. We find that the different locomotor activities of soldiers compared with those of neotenics and workers probably reflect their physiological differentiation. The present study provides a basis for a deeper understanding of the roles of individual locomotor activities in social behaviours.     

Reproductive isolation via divergent genital morphology due to cascade reinforcement in Ohomopterus ground beetles

Secondary contact between incipient species and selection against maladaptive hybridization can drive reinforcement between populations in contact and result in reproductive character displacement (RCD). Resultant divergence in mating traits within a species may generate downstream reproductive isolation between populations with displaced and non-displaced traits, referred to as the cascade reinforcement hypothesis. We examined this hypothesis using three allopatric populations of the ground beetle Carabus maiyasanus with a genital lock-and-key system. This species shows RCD in male and female genital morphologies in populations in contact with the sister species C. iwawakianus. In a reciprocal mating experiment using three allopatric populations with differences in male and female genital sizes, insemination failure increased as the difference in genital size increased. Based on the reproductive isolation index, insemination failure was the major postmating-prezygotic isolation barrier, at least in one population pair with comparable total isolation to those of other species pairs. By contrast, there was only incomplete premating isolation among populations. These results suggest that RCD in genital morphologies drives incipient allopatric speciation, supporting the cascade reinforcement hypothesis. These findings provide insight into the roles of interspecific interactions and subsequent trait diversification in speciation processes.     

Comparison of dynamic responses of cellular metabolites in <Emphasis Type="Italic">Escherichia coli</Emphasis> to pulse addition of substrates

We conducted an integrated study of cell growth parameters, product formation, and the dynamics of intracellular metabolite concentrations using Escherichia coli with genes knocked out in the glycolytic and oxidative pentose phosphate pathway (PPP) for glucose catabolism. We investigated the same characteristics in the wild-type strain, using acetate or pyruvate as the sole carbon source. Dramatic effects on growth parameters and extracellular and intracellular metabolite concentrations were observed after blocking either glycolytic breakdown of glucose by inactivation of phosphoglucose isomerase (disruption of pgi gene) or pentose phosphate breakdown of glucose by inactivation of glucose-6-phosphate dehydrogenase (disruption of zwf gene). Reducing power (NADPH) was mainly produced through PPP when the pgi gene was knocked out, while NADPH was produced through the tricarboxylic acid (TCA) cycle by isocitrate dehydrogenase or NADP-linked malic enzyme when the zwf gene was knocked out. As expected, when the pgi gene was knocked out, intracellular concentrations of PPP metabolites were high and glycolytic and concentrations of TCA cycle pathway metabolites were low. In the zwf gene knockout, concentrations of PPP metabolites were low and concentrations of intracellular glycolytic and TCA cycle metabolites were high.     

Optical coherence tomography for dynamic investigation of mammalian reproductive processes

The biological events associated with mammalian reproductive processes are highly dynamic and tightly regulated by molecular, genetic, and biomechanical factors. Implementation of live imaging in reproductive research is vital for the advancement of our understanding of normal reproductive physiology and for improving the management of reproductive disorders. Optical coherence tomography (OCT) is emerging as a promising tool for dynamic volumetric imaging of various reproductive processes in mice and other animal models. In this review, we summarize recent studies employing OCT-based approaches toward the investigation of reproductive processes in both, males and females. We describe how OCT can be applied to study structural features of the male reproductive system and sperm transport through the male reproductive tract. We review OCT applications for in vitro and dynamic in vivo imaging of the female reproductive system, staging and tracking of oocytes and embryos, and investigations of the oocyte/embryo transport through the oviduct. We describe how the functional OCT approach can be applied to the analysis of cilia dynamics within the male and female reproductive systems. We also discuss the areas of research, where OCT could find potential applications to progress our understanding of normal reproductive physiology and reproductive disorders.     

Initial burst of root development with decreasing respiratory carbon cost in Fagus crenata Blume seedlings

As terrestrial plants are rooted in one place, their metabolism must be acclimatized to continuously changing environmental conditions. This process is influenced by different metabolic traits of plant organs during ontogeny. However, direct measurement of organ-specific metabolic rates is particularly scarce, and little is known about their roles in whole-plant metabolism. In this study, we investigated size scaling of respiration rate, fresh mass and surface area of leaves, stems and roots in 65 seedlings of Fagus crenata Blume (2 weeks to 16 months old). With the increase in plant mass, the proportion of roots in whole plants increased from 20.8 to 87.3% in fresh mass and from 12.8 to 95.0% in surface area, whereas there was only a 15.6 to 60.2% increase in respiration rate. As a result, the fresh-mass-specific and surface-area-specific respiration rates in the roots decreased by 85% and 90%, respectively, and these decreases were significantly size dependent. However, such a size-dependent decrease was not observed for the surface-area-specific respiration rate in the leaves and stems. It is likely that this rapid root development is specific to the early growth stage after germination and would help plants acquire water and nutrients efficiently (i.e., at relatively low respiratory carbon costs). Overall, it is probable that the establishment of F. crenata forests and survival of F. crenata seedlings could be promoted by substantial root growth, with a reduction in respiratory carbon cost.