共查询到20条相似文献,搜索用时 15 毫秒
1.
Rowland T 《European journal of applied physiology》2007,101(1):61-66
The relationship between circulatory flow (Q) and oxygen uptake (
) may provide insights into performance of peripheral mechanisms which govern blood flow during exercise (circulatory efficacy).
This study evaluated the response of Q relative to during progressive upright cycle exercise in a group of 39 preadolescent boys (mean age 12.2 ± SD 0.5 years). The Q– relationship was curvilinear, best described by the cubic equation Q = 3.60()3 + 5.24()2 + 2.40() − 0.94. Circulatory efficacy, defined as the %ΔQ/%Δ × 100, fell from 70.4% between the first two workloads to 49.7% at peak exercise. This decline in circulatory efficacy is
consistent with other published data suggesting a decline in skeletal muscle pump function at high intensity workloads. The
pattern of change in relationship of Q and during progressive exercise in these children is similar to that observed in studies of adults. This implies that performance
of peripheral determinants of circulatory responses to exercise is not affected by biological maturation. 相似文献
2.
Kleschenko YE Karpenko LP Villalta F 《Bulletin of experimental biology and medicine》2010,149(6):731-733
Human defensin-α1 is a biologically active peptide exhibiting a dose-dependent trypanocidal effect in vitro against trypomastigotes and amastigotes of Trypanosoma cruzi line Tulahuen. This effect is determined by fragmentation of parasite DNA reducing the capacity of passaged T. cruzi to invade HeLa cells. 相似文献
3.
The PSO3 gene of Saccharomyces cerevisiae was molecularly cloned by complementing the cold-sensitivity phenotype of a pso3-1 mutant and was found to be allelic to RNR4, encoding one of the two DNA damage-inducible small subunits of the ribonucleotide reductase (RNR) complex. Compared to a
rnr4Δ mutant that allows only very little mutation induction at very low doses of 254nm ultraviolet light (UVC), the pso3-1 mutant allele confers leakiness in that it permits some DNA damage-induced mutagenesis at low doses of UVC. Similarly, the
pso3 mutant is slightly less sensitive to UVC than an rnr4Δ mutant. Cloning and sequencing of the RNR4 locus of the pso3-1 mutant revealed that its intermediate phenotype is attributable to a G → A transition at nucleotide 352, leading to replacement
of glycine by arginine [G118R] in the mutant’s protein. Both RNR4 mutant alleles confer significantly less sensitivity to UVC than mutant alleles of non-UVC-mutable REV3, indicating that, apart from nucleotide excision repair, RAD6-dependent error-free DNA repair may still be functional. The phenotype of a strongly reduced UVC-induced mutagenesis for
rnr4 mutant alleles has not yet been described; it suggests the importance of this gene for a fully functional RNR providing correct
amounts of DNA precursor molecules, thereby, allowing translesion synthesis (error-prone) of UVC-damaged DNA. Stationary phase
cells of the rnr4Δ mutant, but not of the original pso3-1 mutant, are swollen with a fourfold to eightfold increase in volume. The central role of RNR in DNA precursor metabolism
and its complex regulation allow for several modes of suppression that may influence the phenotypes of RNR4 mutants, especially those containing the leaky pso3-1 mutant allele. 相似文献
4.
Hill DW Stephens LP Blumoff-Ross SA Poole DC Smith JC 《European journal of applied physiology》2003,89(6):564-569
The purpose of this study was to determine the effect of sampling strategy (i.e., number of breaths) on measured peak rate
of oxygen uptake (V̇O2peak) elicited by a range of severe intensity exercise bouts. The hypothesis was that a smaller sample (i.e., fewer breaths) would
produce a higher measure of V̇O2peak and that this effect would be greater in shorter tests than in longer tests. Thirty-three university students performed constant-power
cycle ergometer tests at intensities selected to elicit fatigue in ~3.0 min (short duration), ~5.5 min (medium duration),
and ~8.0 min (long duration). Values for V̇O2peak were the highest rates of oxygen uptake obtained using the following sampling methods: single breath, and 3-, 5-, 15- and
30-breath rolling averages. As hypothesized, measures of V̇O2peak increased systematically with decreasing sample size. Contrary to the hypothesis, the effect of sample size was greater in
medium duration and long duration tests than in the short duration tests. The interaction between test duration and sample
size on measures of V̇O2peak highlights the importance of standardizing the analysis protocol for exercise in the severe domain. If such standardization
is not feasible, it should be recognized that specific analysis protocols may exert a substantial effect upon the reported V̇O2peak. 相似文献
5.
The Acremonium chryrsogenum cefT gene encoding a membrane protein of the major facilitator superfamily implicated in the cephalosporin biosynthesis in A. chrysogenum was introduced into Penicillium chrysogenum Wisconsin 54-1255 (a benzylpenicillin producer), P. chrysogenum npe6 pyrG (-) (a derivative of Wisconsin 54-1255 lacking a functional penDE gene) and P. chrysogenum TA98 (a deacetylcephalosporin producer containing the cefD1, cefD2, cefEF and cefG genes from A. chrysogenum). RT-PCR analysis revealed that the cefT gene was expressed in P. chrysogenum strains. HPLC analysis of the culture broths of the TA98 transformants showed an increase in the secretion of deacetylcephalosporin C and hydrophilic penicillins (isopenicillin N and penicillin N). P. chrysogenum Wisconsin 54-1255 strain transformed with cefT showed increased secretion of the isopenicillin N intermediate and a drastic decrease in the benzylpenicillin production. Southern and northern blot analysis indicated that the untransformed P. chrysogenum strains contain an endogenous gene similar to cefT that may be involved in the well-known secretion of the isopenicillin N intermediate. In summary, the cefT transporter is a hydrophilic beta-lactam transporter that is involved in the secretion of hydrophilic beta-lactams containing alpha-aminoadipic acid side chain (isopenicillin N, penicillin N and deacetylcephalosporin C). 相似文献
6.
Kirchgässner M Schmahl G Al-Quraishy S Ghaffar FA Mehlhorn H 《Parasitology research》2008,103(3):603-607
In the present study, larvae of Ascaris suum and Trichuris muris were investigated by light and electron microscopy after incubation in a hatching medium containing 89% phosphate-buffered saline (pH 7.4), 10% RPMI-1640 and 1% sodiumhypochlorite at 40 and 37 degrees C, respectively. The larvae were obtained from fertilised eggs of the worms during defined phases of development (A. suum, 36th-50th day of development; T. muris, once a week from week 16 to 20). Light and electron micrographs of the larvae gave evidence that the third larval stage of A. suum is probably the infectious stage. The first moult of the larvae had already taken place before the 36th day of incubation starting at day 1. After 36 days of incubation, only the second larval stage was found within eggs. Some of these larvae were coated by a separated sheath so that a second moult of the larvae is reasonable. On the other hand, no sheathed larvae of T. muris were found in the eggs incubated for 20 weeks in distilled water. No signs of moult were seen for 20 weeks neither on light nor on the electron micrographs. Therefore, in T. muris, the first larval stage is the infectious stage, which was proven by means of re-infections of mice 16, 18 or 20 weeks after incubation of the eggs. 相似文献
7.
Xiaofeng Niu Fang Liu Weifeng Li Wenbing Zhi Hailin Zhang Xiumei Wang Zehong He 《Inflammation》2017,40(4):1111-1122
Acute lung injury (ALI) is characterized by widespread inflammation in the lungs and alveolar-capillary destruction, causing high morbidity and mortality. Cavidine, isolated from Corydalis impatiens, have been exhibited to have potent anti-inflammatory effects in previous studies. The purpose of this study was to evaluate the protective effect of cavidine on lipopolysaccharide (LPS)-induced ALI and to enunciate the underlying in vivo and in vitro mechanisms. Mice were intraperitoneally administrated with cavidine (1, 3, or 10 mg/kg) at 1 and 12 h, prior to the induction of ALI by intranasal administration of LPS (30 mg/kg). Blood samples, lung tissues, and bronchoalveolar lavage fluid (BALF) were harvested after LPS challenge. Furthermore, we used LPS-induced lung epithelial cells A549 to examine the mechanism of cavidine to lung injury. The results showed that pretreatment with cavidine significantly decreased lung wet-to-dry weight (W/D) ratio, reduced pro-inflammatory cytokine levels including TNF-α and IL-6 in BALF and serum from LPS-stimulated mice, and attenuated lung histopathological changes. In addition, western blot results showed that cavidine inhibited the phosphorylation of nuclear factor-kappaB (NF-κB) p65 and IκBα induced by LPS. In conclusion, our results demonstrate that cavidine protects against LPS-induced acute lung injury in mice via inhibiting of pro-inflammatory cytokine TNF-α and IL-6 production and NF-κB signaling pathway activation. Taken together, cavidine may be useful for the prevention and treatment of pulmonary inflammatory diseases, such as ALI. 相似文献
8.
9.
RNA primer removal from Okazaki fragments during lagging-strand replication and the excision of damaged DNA bases requires the action of structure-specific nucleases, such as the mammalian flap endonuclease 1 (FEN-1). This nuclease contains two conserved motifs enriched with acidic amino acid residues that are important for catalytic function. Similar motifs have been identified in nucleases found in viruses, archebacteria, eubacteria, and in eukaryotes ranging from yeast to humans. Unique among these proteins, the putative FEN-1 homologue in Escherichia coli is contained within the N-terminal region of the DNA polymerase I (PolN). To demonstrate that the cellular functions of FEN-1 reside in PolN, we cloned and expressed the amino terminal domain (323 amino acid residues) of PolI in a Saccharomyces cerevisiae strain lacking the FEN-1 homologue RAD27. Overexpression of PolN suppressed, to varying degrees, phenotypes associated with a rad27 null strain. These include temperature sensitivity, Okazaki fragment processing, a mutator phenotype, a G2/M cell cycle arrest, minichromosome loss, and methyl methane sulfonate sensitivity. We purified Rad27 and PolN proteins in order to determine whether differences in their intrinsic nuclease activities or interaction with proliferating cell nuclear antigen (PCNA) could explain the partial suppression of some phenotypes. We found that the in vitro nuclease activities of Rad27 were more potent than those of PolN and the activity of Rad27, but not PolN, was stimulated by PCNA. We conclude that the N-terminal nuclease domain of E. coli polymerase I encodes a functional homologue of FEN-1. 相似文献
10.
A new species of sandfly is described from limestone caves in Thailand. The inclusion of this species in the subgenus Euphlebotomus is justified on the basis of characters of the male genitalia (paramere, basal lobe). The male–female gathering in the same
taxon is based on ecological (cavernicolous species), morphological (length of male genital filaments and female spermathecal
ducts) and molecular (homology of cytochrome b mt DNA sequences) criteria. A differential diagnosis between Phlebotomus mascomai n. sp. and P. argentipes Annandale & Brunetti, the vector of Leishmania donovani (Laveran & Mesnil) in India, is proposed based on several morphological characters like antennal formula and genitalia. 相似文献
11.
van der Nest MA Slippers B Stenlid J Wilken PM Vasaitis R Wingfield MJ Wingfield BD 《Current genetics》2008,53(6):323-336
This study considered the systems controlling sexual and self-recognition in Amylostereum areolatum, a homobasidiomycetous symbiont of the Sirex woodwasp. To investigate the structure and organization of these systems in A. areolatum, we identified a portion of a putative homologue (RAB1) of the pheromone receptor genes of Schizophyllum commune and Coprinus cinereus, and a portion of a putative homologue of the S. commune mitochondrial intermediate peptidase (mip) gene. Diagnostic DNA-based assays for mating-type were developed and their application confirmed that the fungus has a heterothallic tetrapolar mating system. Segregation analysis showed that RAB1 is linked to mating-type B, while mip is linked to mating-type A. The results of sexual and vegetative compatibility tests suggest that sexual recognition in A. areolatum is controlled by two multiallelic mat loci, while self-recognition is controlled by at least two multiallelic het loci. Therefore, despite the association of A. areolatum with the woodwasp and the unique mixture of sexual and clonal reproduction of the fungus, both recognition systems of the fungus appear to be similar in structure and function to those of other homobasidiomycetes. This is the first report regarding the genes controlling recognition of a homobasidiomycete involved in an obligate mutualistic relationship with an insect. 相似文献
12.
The effects of ̇raining and/or ageing upon maximal oxygen uptake (O2max) and heart rate values at rest (HRrest) and maximal exercise (HRmax), respectively, suggest a relationship between O2max and the HRmax-to-HRrest ratio which may be of use for indirect testing of O2max. Fick principle calculations supplemented by literature data on maximum-to-rest ratios for stroke volume and the arterio-venous O2 difference suggest that the conversion factor between mass-specific O2max (ml·min–1·kg–1) and HRmax·HRrest
–1 is ~15. In the study we experimentally examined this relationship and evaluated its potential for prediction of O2max. O2max was measured in 46 well-trained men (age 21–51 years) during a treadmill protocol. A subgroup (n=10) demonstrated that the proportionality factor between HRmax·HRrest
–1 and mass-specific O2max was 15.3 (0.7) ml·min–1·kg–1. Using this value, O2max in the remaining 36 individuals could be estimated with an SEE of 0.21 l·min–1 or 2.7 ml·min–1·kg–1 (~4.5%). This compares favourably with other common indirect tests. When replacing measured HRmax with an age-predicted one, SEE was 0.37 l·min–1 and 4.7 ml·min–1·kg–1 (~7.8%), which is still comparable with other indirect tests. We conclude that the HRmax-to-HRrest ratio may provide a tool for estimation of O2max in well-trained men. The applicability of the test principle in relation to other groups will have to await direct validation. O2max can be estimated indirectly from the measured HRmax-to-HRrest ratio with an accuracy that compares favourably with that of other common indirect tests. The results also suggest that the test may be of use for O2max estimation based on resting measurements alone.An erratum to this article can be found at 相似文献
13.
A total of 51 faecal samples from wild and farmed mink were analysed by a direct immunofluorescence antibody test. Cryptosporidium oocysts were identified in eight, apparently healthy, farmed American mink (Mustela vison). The isolates were identified as Cryptosporidium parvum ‘ferret’ genotype by PCR-RFLP and sequencing analysis of a 341-base-pair fragment of the Cryptosporidium oocyst wall protein (COWP) gene. This is the first report of Cryptosporidium in American mink.
Genbank accession numbers of the sequences used in this study C. parvum, ‘bovine’ genotype AF266273; C. hominis, AF266265; C. parvum, ‘mouse’ genotype AF266268, C. wrairi, U35027; C. parvum, ‘ferret’ genotype AF266267; C. meleagridis, AF266266; C. parvum, ‘marsupial’ genotype AF266269; C. parvum, ‘pig’ genotype AF266270; C. canis, AF266274; C. felis, AF266263; C. baileyi, AF266276; C. serpentis, AF266275; C. andersoni, AF266262 and C. muris, AF161579 相似文献
14.
In opposite to the free-living soil nematode Caenorhabditis elegans, the genetic regulation of hypobiosis or inhibited or arrested development in parasitic nematodes is completely unknown.
In C. elegans, the daf-genes or the age-1 gene are of major importance in signaling pathways regulating arrested development. To investigate if orthologs of these
genes are present in the bovine lungworm Dictyocaulus viviparus, a PCR analysis with gene-specific primer combinations was performed. No orthologs of the age-1 or daf-genes could be identified in D. viviparus. The possible differences in the role of the daf-genes concerning arrested development in parasitic and free-living nematodes will be discussed. 相似文献
15.
16.
While the counterselectable Schizosaccharomyces pombe
ura4
+ gene can be used to prepare a site in the S. pombe genome to receive an unmarked mutant allele (loss of ura4
+ confers 5FOA-resistant (5FOAR) growth), the desired unmarked knock-in strains are generally outnumbered by spontaneously arising 5FOAR mutants. Relative to the same approach using the homologous URA3
+ gene in Saccharomyces cerevisiae, knock-ins in S. pombe are harder to identify due to a lower efficiency of homologous recombination and a relatively high background of spontaneous
5FOAR colonies. To develop an improved method for identifying cells receiving unmarked mutant alleles, we first determined that
5FOAR strains carry mutations in either of two genes; ura4
+ and ura5
+. We then cloned the S. pombe
ura5
+ orotate phosphoribosyltransferase gene and constructed a 2.1 kb cassette containing ura5
+ together with the S. pombe lys7
+ gene. Using this doubly marked cassette to disrupt the sck1
+ kinase gene, we can distinguish between strains created by homologous knock-in of unmarked wild-type or kinase-dead alleles
and spontaneously arising ura4
− and ura5
− mutants by screening 5FOAR colonies for the loss of the lys7
+ marker. The utility of this system, especially when the phenotype for the strain carrying the knock-in allele is indistinguishable
from that of the disruption strain, is borne out by the fact that ~95% of 5FOAR colonies in our studies arose from background ura4
− and ura5
− mutations. 相似文献
17.
Southern analysis with rpl5 and rps14 mtDNA gene probes of Solanum tuberosum, S. commersonii and a sample of somatic hybrids detected polymorphisms between parents and the appearance of a novel restriction fragment in various hybrids. In one of them, detailed mtDNA analyses revealed various configurations of the rpl5–rps14 region present at different stoichiometries. Multiple inter-parental recombination events across homologous sequences were assumed to have caused these rearrangements. Sequence similarity searches detected one sequence putatively involved in the recombination upstream of the rpl5 gene. The presence of a second recombinogenic sequence was inferred. We propose two models to explain the mechanism responsible for obtaining the different rpl5–rps14 arrangements shown after somatic hybridization. Variability in the rpl5–rps14 region observed in both the parental species and their somatic hybrids suggests this region is a hot spot for mtDNA rearrangements in Solanum spp.Contribution no. 39 from the Institute of Plant Genetics, Research Division of Portici.Communicated by A. Brennicke 相似文献
18.
The ovc mutant of Neurospora crassa accumulates more carotenoids than the wild type in the light, is sensitive to high osmotic pressure and exhibits an altered aerial development. The three traits are complemented by a single gene, cut-1, but only the two latter are exhibited by a mutant of this gene carrying a premature stop mutation. Targeted cut-1 deletion results in a normal carotenoid content, confirming the involvement of at least a second gene in the carotenoid-overproducing phenotype of the ovc strain. Molecular analysis of ovc genomic DNA indicates the absence of a large DNA segment affecting the gene cut-1. A PCR walking approach allowed the identification of a deletion extending along 77,078 bp on linkage group IV. The break-points are located in ApA/TpT sequences, suggesting the involvement of UV-induced thymine dimers in the origin of the deletion. The ovc mutant lacks 21 predicted ORFs, including cut-1 as the only known genetic marker, and four ORFs from a 22-member transmethylase gene family. Ten ORFs have no similarity with any predicted gene from other species. Three of them are closely related by sequence and linkage, evoking ancestral gene duplications.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
19.
Adams JA Moore JE Moreno MR Coelho J Bassuk J Wu D 《Annals of biomedical engineering》2003,31(11):1337-1346
Periodic acceleration (pGz), a novel method of ventilatory support, is achieved using a platform that moves cyclically in the headward–footward direction. PGz has been shown to increase vascular shear stress and regional blood flows, as well as decrease pulmonary and systemic vascular resistances. PGz also increases nitric oxide (NO) production. This study was undertaken to determine the effects of pGz on the NO inhibiting effects of N-w-nitro–L-arginine (L-NAME) in vivo, and to determine if increased NO production due to pGz could be reproduced in vitro with isolated arteries. Pigs were assigned to conventional ventilation (CV), or pGz, with no additional breathing assistance. L-NAME was infused in cumulative doses of 1, 3, 10, 30, and 100 mg/kg. Cardiac output decreased in both groups by 50%. There was also a dose-dependent increase in blood pressure, pulmonary artery pressure, and vascular resistances. However, pGz attenuated the vascular response of L-NAME. Isolated porcine aortas exposed to nonpulsatile, pulsatile, and pulsatile flow plus pGz exhibited an increase in nitrites with the addition of pulsatile flow (300%, relative to steady flow), and a further increase with pGz (1000%, relative to steady flow). It has been determined that pGz, a novel method of increasing shear stress on the vascular endothelium, attenuates the vasoactive response to L-NAME. The in vitro experiments demonstrated that increases in NO production in vivo could be reproduced in vitro, which provides the opportunity to investigate the mechanisms of cardiovascular pGz effects. © 2003 Biomedical Engineering Society.
PAC2003: 8719Uv, 8719Rr, 8780-y 相似文献
20.
In the great majority of sexual eukaryotes, mitochondrial genomes are inherited almost exclusively from a single parent. While
many hypotheses have been proposed to explain this phenomenon, very little is known about the genetic elements controlling
uniparental mitochondria inheritance. In the bipolar, isogamous basidiomycete yeast Cryptococcus neoformans, progeny from crosses between strains of mating type a (MATa) and mating type α (MATα) typically inherit mitochondrial DNA
(mtDNA) from the MATa parent. We recently demonstrated that a mating type α (MATα)-specific gene SXI1α, controls mitochondrial inheritance in C. neoformans. Here, we show that another homeodomain gene SXI2a in the alternative mating type MATa is also required for uniparental mtDNA inheritance in this fungus. Disruption of SXI2a resulted in biparental mtDNA inheritance in the zygote population with significant numbers of progeny inheriting mtDNA from
the MATa parent, the MATα parent, and both the MATa and the MATα parents. In addition, progeny from same-sex mating between
MATα strains showed a biparental mitochondrial inheritance pattern. Our results suggest that SXI1α and SXI2a coordinately control uniparental mitochondrial inheritance in C. neoformans. 相似文献