A protein involved in co-ordinated regulation of inorganic carbon and glucose metabolism in the facultative photoautotrophic cyanobacteriumSynechocystis PCC6803

The involvement of a gene ofSynechocystis PCC6803,icfG, in the co-ordinated regulation of inorganic carbon and glucose metabolism, was established. TheicfG gene codes for a 72 kDa protein, which shows no homology with those registered in data libraries. Expression oficfG required glucose, the actual inducer probably being glucose-6-phosphate, and was independent of light and of the external inorganic carbon concentration. Mutants carrying an inactivated copy oficfG were constructed. Their growth characteristics were identical to those of the wild type under all regimes except in limiting inorganic carbon with glucose being present either before or after the transfer to the limiting conditions. These conditions completely prevented growth, both in the light and in the dark. The inhibition could be relieved by several intermediates of the tricarboxylic acid cycle. Assays of various enzymic activities related to inorganic carbon uptake and to its assimilationvia either the Calvin cycle or phosphoenolpyruvate carboxylase did not reveal the level of action of IcfG. Possible models include a blockage of the assimilation of both carbon sources in the absence of IcfG, or the inhibition of Ci incorporation route(s) essential under limiting inorganic carbon conditions, even when glucose is present, and even in the dark.     

Spontaneous Reperfusion after In Situ Thromboembolic Stroke in Mice

Injection of thrombin into the middle cerebral artery (MCA) of mice has been proposed as a new model of thromboembolic stroke. The present study used sequential multiparametric Magnetic Resonance Imaging (MRI), including Magnetic Resonance Angiography (MRA), Diffusion-Weighted Imaging (DWI) and Perfusion-Weighted Imaging (PWI), to document MCA occlusion, PWI-DWI mismatch, and lesion development. In the first experiment, complete MCA occlusion and reproducible hypoperfusion were obtained in 85% of animals during the first hour after stroke onset. In the second experiment, 80% of animals showed partial to complete reperfusion during a three-hour follow-up. Spontaneous reperfusion thus contributed to the variability in ischemic volume in this model. The study confirmed the value of the model for evaluating new thrombolytic treatments, but calls for extended MRI follow-up at the acute stage in therapeutic studies.     

Cyclooxygenases and lipoxygenases are used by the fungus Podospora anserina to repel nematodes

Oxylipins are secondary messengers used universally in the living world for communication and defense. The paradigm is that they are produced enzymatically for the eicosanoids and non-enzymatically for the isoprostanoids. They are supposed to be degraded into volatile organic compounds (VOCs) and to participate in aroma production. Some such chemicals composed of eight carbons are also envisoned as alternatives to fossil fuels. In fungi, oxylipins have been mostly studied in Aspergilli and shown to be involved in signalling asexual versus sexual development, mycotoxin production and interaction with the host for pathogenic species. Through targeted gene deletions of genes encoding oxylipin-producing enzymes and chemical analysis of oxylipins and volatile organic compounds, we show that in the distantly-related ascomycete Podospora anserina, isoprostanoids are likely produced enzymatically. We show the disappearance in the mutants lacking lipoxygenases and cyclooxygenases of the production of 10-hydroxy-octadecadienoic acid and that of 1-octen-3-ol, a common volatile compound. Importantly, this was correlated with the inability of the mutants to repel nematodes as efficiently as the wild type. Overall, our data show that in this fungus, oxylipins are not involved in signalling development but may rather be used directly or as precursors in the production of odors against potential agressors.

Motion control of musculoskeletal systems with redundancy

Motion control of musculoskeletal systems for functional electrical stimulation (FES) is a challenging problem due to the inherent complexity of the systems. These include being highly nonlinear, strongly coupled, time-varying, time-delayed, and redundant. The redundancy in particular makes it difficult to find an inverse model of the system for control purposes. We have developed a control system for multiple input multiple output (MIMO) redundant musculoskeletal systems with little prior information. The proposed method separates the steady-state properties from the dynamic properties. The dynamic control uses a steady-state inverse model and is implemented with both a PID controller for disturbance rejection and an artificial neural network (ANN) feedforward controller for fast trajectory tracking. A mechanism to control the sum of the muscle excitation levels is also included. To test the performance of the proposed control system, a two degree of freedom ankle–subtalar joint model with eight muscles was used. The simulation results show that separation of steady-state and dynamic control allow small output tracking errors for different reference trajectories such as pseudo-step, sinusoidal and filtered random signals. The proposed control method also demonstrated robustness against system parameter and controller parameter variations. A possible application of this control algorithm is FES control using multiple contact cuff electrodes where mathematical modeling is not feasible and the redundancy makes the control of dynamic movement difficult.     

Genus-level taxonomic changes implied by the mitochondrial phylogeny of grey mullets (Teleostei: Mugilidae)

A comprehensive mitochondrial phylogeny of the family Mugilidae (Durand et al., Mol. Phylogenet. Evol. 64 (2012) 73–92 [1]) demonstrated the polyphyly or paraphyly of a proportion of the 20 genera in the family. Based on these results, here we propose a revised classification with 25 genera, including 15 genera currently recognized as valid (Agonostomus, Aldrichetta, Cestraeus, Chaenomugil, Chelon, Crenimugil, Ellochelon, Joturus, Mugil, Myxus, Neomyxus, Oedalechilus, Rhinomugil, Sicamugil and Trachystoma), 7 resurrected genera [Dajaus (for Agonostomus monticola), Gracilimugil (for Liza argentea), Minimugil (for Sicamugil cascasia), Osteomugil (for several species currently under Moolgarda and Valamugil, including M. cunnesius, M. engeli, M. perusii, and V. robustus), Planiliza (for Indo-Pacific Chelon spp., Indo-Pacific Liza spp., and Paramugil parmatus), Plicomugil (for Oedalechilus labiosus), and Squalomugil (for Rhinomugil nasutus)] and 3 new genera: Neochelon gen. nov. (for Liza falcipinnis), Parachelon gen. nov. (for L. grandisquamis) and Pseudomyxus gen. nov. (for Myxus capensis). Genus Chelon was shown to include exclusively Chelon spp. and Liza spp. from the Atlantic and the Mediterranean, and Liza spp. species endemic to eastern southern Africa. Genus Crenimugil should now include C. crenilabis, Moolgarda seheli and V. buchanani. Genus names Liza, Moolgarda, Paramugil, Valamugil and Xenomugil should be abandoned because they are no longer valid. Further genetic evidence is required to confirm or infirm the validity of the genus Paracrenimugil Senou 1988. The mitochondrial phylogeny of the 25 genera from the present revision is the following: [(Sicamugil, (Minimugil, Rhinomugil)); Trachystoma; ((Myxus, Neomyxus), (Cestraeus, Chaenomugil, (Agonostomus, Dajaus, Joturus), Mugil)); (Aldrichetta, Gracilimugil); Neochelon gen. nov.; (Pseudomyxus gen. nov., (Chelon, Oedalechilus, Planiliza, Parachelon gen. nov.)); ((Squalomugil, (Ellochelon, Plicomugil)), (Crenimugil, Osteomugil))]. Agonostomus monticola and several species with large distribution ranges (including Moolgarda seheli, Mugil cephalus and M. curema) consist of separate lineages whose geographic distribution suggests they are cryptic species, thus warranting further taxonomic work in the Mugilidae at the infra-generic level.