76 resultados para Comparative and Evolutionary Physiology


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An unknown Gram-positive, catalase-positive, facultatively anaerobic, non-spore-forming, coccus-shaped bacterium originating from sediment was characterized using phenotypic, molecular chemical and molecular phylogenetic methods. Chemical studies revealed the presence of a cell-wall murein based on LL-diaminopimelic acid (type LL-Dpm-glycine(1)), a complex mixture of saturated, monounsaturated and iso- and anteiso-methyl-branched, non-hydroxylated, long-chain cellular fatty acids and tetrahydrogenated menaquinones with eight isoprene units [MK-8(H-4)] as the major respiratory lipoquinone. This combination of characteristics somewhat resembled members of the suborder Micrococcineae, but did not correspond to any currently described species. Comparative 16S rRNA gene sequencing confirmed that the unidentified coccus-shaped organism is a member of the Actinobacteria and represents a hitherto-unknown subline related to, albeit different from, a number of taxa including Intrasporangium, Janibacter, Terrabacter, Terracoccus and Ornithinicoccus. Based on phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium originating from lake sediment be classified as a new genus and species, Arsenicicoccus bolidensis gen. nov., sp. nov. (type strain CCUG 47306(T) = DSM 15745(T)).

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An unusual catalase-positive, Gram-positive, coccus-shaped bacterium that originated from a human blood specimen was subjected to a polyphasic taxonomic study. Cell-wall murein and lipid composition analyses indicated that the unknown isolate was a member of the genus Luteococcus. The results of comparative 16S rRNA gene sequence analysis were consistent with chemotaxonomic findings and showed that the unidentified bacterium represents a hitherto unknown sublineage, within the genus Luteococcus that is closely related to, but distinct from, Luteococcus japonicus. On the basis of both phenotypic and phylogenetic evidence, it is proposed that the unknown bacterium from human blood should be classified as Luteococcus sanguinis sp. nov., with the type strain CCUG 33897(T) (=CIP 107216(T)).

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A previously unknown Gram-positive, non-spore-forming, non-lipophilic, catalase-positive, irregular rod-shaped bacterium (M/106/00/5(T)) was isolated, in mixed culture, from the penis of a Caspian seal (Phoca caspica). The strain was a facultative anaerobe that was able to grow at 22 and 42 degreesC. Comparative 16S rRNA gene sequencing showed that the organism formed a hitherto unknown subline within the genus Corynebacterium. Sequence divergence values of more than 5 % from other described Corynebacterium species, together with phenotypic differences, showed that the unidentified bacterium represents a previously unrecognized member of this genus. On the basis of phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium isolated from a Caspian seal (strain M/106/00/5(T) = CCUG 44566(T)=CIP 107965(T)) be classified as the type strain of a novel species of the genus Corynebacterium, Corynebacterium caspium sp. nov.

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An unknown Gram-positive, catalase-negative, facultatively anaerobic, non-spore-forming, rod-shaped bacterium originating from semen of a pig was characterized using phenotypic, molecular chemical and molecular phylogenetic methods. Chemical studies revealed the presence of a directly cross-linked cell wall murein based on L-lysine and a DNA G + C content of 39 mol%. Comparative 16S rRNA gene sequencing showed that the unidentified rod-shaped organism formed a hitherto unknown subline related, albeit loosely, to Alkalibacterium olivapovliticus, Alloiococcus otitis, Dolosigranulum pigrum and related organisms, in the low-G + C-content Gram-positive bacteria. However, sequence divergence values of > 11 % from these recognized taxa. clearly indicated that the novel bacterium represents a separate genus. Based on phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium from pig semen be classified as a new genus and species, Allofustis seminis gen. nov., sp. nov. The type strain is strain 01-570-1(T) (=CCUG 45438(T)=CIP 107425(T)).

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A previously undescribed, Gram-positive, catalase-negative, coccus-shaped organism that originated from a human wound was subjected to taxonomic study. On the basis of its cellular morphology and the results of biochemical testing, the unknown organism was identified tentatively as a member of the genus Helcococcus, but it did not correspond to either of the two recognized species of this genus. Comparative 16S rRNA gene sequencing studies confirmed that the bacterium was associated phylogenetically with the genus Helcococcus, with the unidentified organism forming a hitherto unknown subline within the genus. On the basis of biochemical, molecular chemical and molecular phylogenetic evidence, it is proposed that the unknown organism that was recovered from a human wound should be classified as a novel species of the genus Helcococcus, namely Helcococcus sueciensis sp. nov. The type strain is CCUG 47334(T) ( = CIP 108183(T)).

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Current intakes of very long chain omega-3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DNA) are low in most individuals living in Western countries. A good natural source of these fatty acids is seafood, especially oily fish. Fish oil capsules contain these fatty acids too. Very long chain w-3 fatty acids are readily incorporated from capsules into transport, functional, and storage pools. This incorporation is dose-dependent and follows a kinetic pattern that is characteristic for each pool. At sufficient levels of incorporation, EPA and DHA influence the physical nature of cell membranes and membrane protein-mediated responses, eicosanoid generation, cell signaling and gene expression in many different cell types. Through these mechanisms, EPA and DHA influence cell and tissue physiology, and the way cells and tissues respond to external signals. In most cases, the effects seen are compatible with improvements in disease biomarker profiles or in health-related outcomes. As a result, very long chain omega-3 fatty acids play a role in achieving optimal health and in protection against disease. Long chain omega-3 fatty acids protect against cardiovascular morbidity and mortality, and might be beneficial in rheumatoid arthritis, inflammatory bowel diseases, childhood learning, and behavior, and adult psychiatric and neurodegenerative illnesses. DHA has an important structural role in the eye and brain, and its supply early in life is known to be of vital importance. On the basis of the recognized health improvements brought about by long chain omega-3 fatty acids, recommendations have been made to increase their intake. (C) 2009 International Union of Biochemistry and Molecular Biology, Inc. Volume 35, Number 3, May/June 2009, Pages 266-272. E-mail: pcc@soton.ac.uk

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Investigation of the anatomical substructure of the medial temporal lobe has revealed a number of highly interconnected areas, which has led some to propose that the region operates as a unitary memory system. However, here we outline the results of a number of studies from our laboratories, which investigate the contributions of the rat's perirhinal cortex and postrhinal cortex to memory, concentrating particularly on their respective roles in memory for objects. By contrasting patterns of impairment and spared abilities on a number of related tasks, we suggest that perirhinal cortex and postrhinal cortex make distinctive contributions to learning and memory: for example, that postrhinal cortex is important in learning about within-scene position and context. We also provide evidence that despite the strong connectivity between these cortical regions and the hippocampus, the hippocampus, as evidenced by lesions of the fornix, has a distinct function of its own-combining information about objects, positions, and contexts.

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Comprehensibility is often raised as a problem with formal notations, yet formal methods practitioners dispute this. In a survey, one interviewee said 'formal specifications are no more difficult to understand than code'. Measurement of comprehension is necessarily comparative and a useful comparison for a specification is against its implementation. Practitioners have an intuitive feel for the comprehension of code. A quantified comparison will transfer this feeling to formal specifications. We performed an experiment to compare the comprehension of a Z specification with that of its implementation in Java. The results indicate there is little difference in comprehensibility between the two. (C) 2004 Elsevier B.V. All rights reserved.

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Objectives. Theoretic modeling and experimental studies suggest that functional electrical stimulation (FES) can improve trunk balance in spinal cord injured subjects. This can have a positive impact on daily life, increasing the volume of bimanual workspace, improving sitting posture, and wheelchair propulsion. A closed loop controller for the stimulation is desirable, as it can potentially decrease muscle fatigue and offer better rejection to disturbances. This paper proposes a biomechanical model of the human trunk, and a procedure for its identification, to be used for the future development of FES controllers. The advantage over previous models resides in the simplicity of the solution proposed, which makes it possible to identify the model just before a stimulation session ( taking into account the variability of the muscle response to the FES). Materials and Methods. The structure of the model is based on previous research on FES and muscle physiology. Some details could not be inferred from previous studies, and were determined from experimental data. Experiments with a paraplegic volunteer were conducted in order to measure the moments exerted by the trunk-passive tissues and artificially stimulated muscles. Data for model identification and validation also were collected. Results. Using the proposed structure and identification procedure, the model could adequately reproduce the moments exerted during the experiments. The study reveals that the stimulated trunk extensors can exert maximal moment when the trunk is in the upright position. In contrast, previous studies show that able-bodied subjects can exert maximal trunk extension when flexed forward. Conclusions. The proposed model and identification procedure are a successful first step toward the development of a model-based controller for trunk FES. The model also gives information on the trunk in unique conditions, normally not observable in able-bodied subjects (ie, subject only to extensor muscles contraction).

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Cell cycle regulatory molecules are implicated in cardiomyocyte hypertrophy. We have investigated protein expression of cyclins A, D1–3, and E and cyclin-dependent kinases (CDKs) 2, 4, 5, and 6 in left ventricular (LV) tissues during the development of LV hypertrophy in rats following aortic constriction (AC). Compared with their expression in sham-operated controls (SH), expression of cyclins D2 and D3 and of CDK4 and CDK6 increased significantly fromday 3 to day 21 after AC concomitant with increased LV mass. However, no significant difference was observed for CDK2 or CDK5. Cyclins A, D1, and E were undetectable. In vitro kinase activities of CDK4 and CDK6 increased ∼70% from day 7 to day 14 in AC myocytes compared with SH myocytes (P< 0.03). Fluorescence-activated cell sorter analysis revealed a G0/G1to G2/M phase progression in AC myocyte nuclei (22.0 ± 1.1% in G2/M) by day 7 postoperation compared with progression in SH myocyte nuclei (14.0 ± 0.8% in G2/M;P < 0.01). Thus an upregulation of certain cell cycle regulators is associated with cardiomyocyte hypertrophy.

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We postulated that the cyclin-dependent kinase inhibitors p21 and p27 could regulate the alterations in growth potential of cardiomyocytes during left ventricular hypertrophy (LVH). LVH was induced in adult rat hearts by aortic constriction (AC) and was monitored at days 0, 1, 3, 7, 14, 21, and 42 postoperation. Relative to sham-operated controls (SH), left ventricle (LV) weight-to-body weight ratio in AC increased progressively with time without significant differences in body weight or right ventricle weight-to-body weight ratio. Atrial natriuretic factor mRNA increased significantly in AC to 287% at day 42 compared with SH (P < 0.05), whereas p21 and p27 mRNA expression in AC rats decreased significantly by 58% (P < 0.03) and 40% (P < 0.05) at day 7, respectively. p21 and p27 protein expression decreased significantly from days 3 to 21 in AC versus SH, concomitant with LV adaptive growth. Immunocytochemistry showed p21 and p27 expression in cardiomyocyte nuclei. Thus downregulation of p21 and p27 may modulate the adaptive growth of cardiomyocytes during pressure overload-induced LVH.

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Five strains of an unusual catalase-negative Gram-positive asporogenous rod-shaped bacterium from human sources were subjected to a polyphasic taxonomic study. The presence of fructose-6-phosphate phosphoketolase, a key enzyme of bifidobacterial hexose metabolism, indicated the strains were members of the genus Bifidobacterium but they did not correspond to any of the recognized species of this genus on the basis of biochemical profiles and whole-cell protein analyses. Comparative 16S rRNA gene sequencing confirmed the placement of the isolates in the genus Bifidobacterium, and demonstrated they represent a hitherto unknown subline within the genus displaying > 5% sequence divergence with recognized species. Based on both phenotypic and phylogenetic criteria, it is proposed that the isolates recovered from human sources be classified as a new species, Bifidobacterium scardovii sp. nov.; the type strain is CCUG 13008T (= DSM 13734T).

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A polyphasic taxonomic study was performed on a previously unidentified gram-positive, facultatively anaerobic, diphtheroid-shaped organism isolated from a vaginal discharge of a horse. Comparative 16S rRNA gene sequencing demonstrated that the strain was a member of the genus Arcanobacterium, but sequence divergence values of >4% with described species of this genus (viz: Arcanobacterium haemolyticum, Arcanobacterium bernardiae, Arcanobacterium phocae, Arcanobacterium pluranimalium and Arcanobacterium pyogenes) demonstrated that the isolate represented a novel species. The unknown bacterium was readily distinguished from other Arcanobacterium species by biochemical tests. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Arcanobacterium hippocoleae sp. nov. The type strain of A. hippocoleae is CCUG 44697T (= CIP 106850T).

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An unknown gram-positive, catalase-positive, strictly aerobic, rod-shaped bacterium was isolated from the nasal cavities of two common seals. Chemical analysis revealed the presence in the bacterium of a hitherto unknown cell-wall murein [type: L-Lys-L-Ala2-Gly(2-3)-L-Ala (Gly)]. Comparative 16S rRNA gene sequencing showed that the unidentified rod was related to the Arthrobacter group of organisms, although sequence divergence values of >3% from established members of this genus indicated that it represents a novel species. On the basis of phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium from seals (Phoca vitulina) be classified as a novel species, Arthrobacter nasiphocae sp. nov. The type strain of Arthrobacter nasiphocae is CCUG 42953T.