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1.
L-Lactate dehydrogenase (L-LDH, E.C. 1.1.1.27) is encoded by two or three loci in all vertebrates examined, with the exception of lampreys, which have a single LDH locus. Biochemical characterizations of LDH proteins have suggested that a gene duplication early in vertebrate evolution gave rise to Ldh-A and Ldh-B and that an additional locus, Ldh-C arose in a number of lineages more recently. Although some phylogenetic studies of LDH protein sequences have supported this pattern of gene duplication, others have contradicted it. In particular, a number of studies have suggested that Ldh-C represents the earliest divergence among vertebrate LDHs and that it may have diverged from the other loci well before the origin of vertebrates. Such hypotheses make explicit statements about the relationship of vertebrate and invertebrate LDHs, but to date, no closely related invertebrate LDH sequences have been available for comparison. We have attempted to provide further data on the timing of gene duplications leading to multiple vertebrate LDHs by determining the cDNA sequence of the LDH of the tunicate Styela plicata. Phylogenetic analyses of this and other LDH sequences provide strong support for the duplications giving rise to multiple vertebrate LDHs having occurred after vertebrates diverged from tunicates. The timing of these LDH duplications is consistent with data from a number of other gene families suggesting widespread gene duplication near the origin of vertebrates. With respect to the relationships among vertebrate LDHs, our data are not consistent with previous claims that Ldh-C represented the earliest divergence. However, the precise relationships among some of the main lineages of vertebrate LDHs were not resolved in our analyses.   相似文献   
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The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.  相似文献   
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The anti-PM/Scl autoantibodies are known to characterize a subset of autoimmune patients with myositis, scleroderma (Scl), and the PM/Scl overlap syndrome. The major autoantigens that are recognized by anti-PM/Scl autoantibodies are designated PM/Scl-100 and PM/Scl-75. These autoantigens have been reported to associate into a large complex consisting of 11 to 16 proteins and to play a role in ribosome synthesis. Recently, it was discovered that the PM/Scl complex is the human counterpart of the yeast (Saccharomyces cerevisiae) exosome, which is an RNA-processing complex consisting of 11 3' → 5' exoribonucleases. To date, 10 human exosome components have been identified, although only some of these were studied in more detail. In this review, we discuss some recent advances in the characterization of the PM/Scl complex.  相似文献   
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Preparations that contain well-spread metaphase chromosomes are critical for plant cytogenetic analyses including chromosome counts, banding procedures, in situ hybridization, karyotyping and construction of ideograms. Chromosome spreading is difficult for plants with large and numerous chromosomes. We report here a technique for obtaining cytoplasm-free, well-spread metaphases from two Amaryllidaceae species: Sprekelia formosissima (2n = 120) and Hymenocallis howardii (2n = 96). The technique has three main steps: 1) pretreatment to cause chromosome condensation, 2) dripping onto tilted slides coated with a thin layer of pure acetic acid and 3) application of steam and acetic acid to produce cytoplasmic hydrolysis, which spreads the chromosomes.  相似文献   
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A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found.  相似文献   
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Malaria is still a major public health problem in Brazil, with approximately 306 000 registered cases in 2009, but it is estimated that in the early 1940s, around six million cases of malaria occurred each year. As a result of the fight against the disease, the number of malaria cases decreased over the years and the smallest numbers of cases to-date were recorded in the 1960s. From the mid-1960s onwards, Brazil underwent a rapid and disorganized settlement process in the Amazon and this migratory movement led to a progressive increase in the number of reported cases. Although the main mosquito vector (Anopheles darlingi) is present in about 80% of the country, currently the incidence of malaria in Brazil is almost exclusively (99,8% of the cases) restricted to the region of the Amazon Basin, where a number of combined factors favors disease transmission and impair the use of standard control procedures. Plasmodium vivax accounts for 83,7% of registered cases, while Plasmodium falciparum is responsible for 16,3% and Plasmodium malariae is seldom observed. Although vivax malaria is thought to cause little mortality, compared to falciparum malaria, it accounts for much of the morbidity and for huge burdens on the prosperity of endemic communities. However, in the last few years a pattern of unusual clinical complications with fatal cases associated with P. vivax have been reported in Brazil and this is a matter of concern for Brazilian malariologists. In addition, the emergence of P. vivax strains resistant to chloroquine in some reports needs to be further investigated. In contrast, asymptomatic infection by P. falciparum and P. vivax has been detected in epidemiological studies in the states of Rondonia and Amazonas, indicating probably a pattern of clinical immunity in both autochthonous and migrant populations. Seropidemiological studies investigating the type of immune responses elicited in naturally-exposed populations to several malaria vaccine candidates in Brazilian populations have also been providing important information on whether immune responses specific to these antigens are generated in natural infections and their immunogenic potential as vaccine candidates. The present difficulties in reducing economic and social risk factors that determine the incidence of malaria in the Amazon Region render impracticable its elimination in the region. As a result, a malaria-integrated control effort - as a joint action on the part of the government and the population - directed towards the elimination or reduction of the risks of death or illness, is the direction adopted by the Brazilian government in the fight against the disease.  相似文献   
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