排序方式: 共有73条查询结果,搜索用时 15 毫秒
31.
Rosiane Serrano Daniel Pacheco Lacerda Ricardo Augusto Cassel Luis Henrique Rodrigues Priscila Ferraz Soares 《Systemic Practice and Action Research》2018,31(3):269-291
Soccer (football) is identified as the most popular sport in the world with a high turnover of economic-financial resources. The different segments of the soccer (football) value chain exert mutual influence on the variables that rule the dynamics of this sector. In this sense it is necessary to identify the variables that represent the soccer (football) value chain systemically; to understand the interrelationships between these variables, the main difficulties derived from this interrelationship and to point out variables that require actions to increment the results of the soccer (football) value chain as a whole. Hence, this study applied a semi-structured questionnaire with open-ended questions about the problems and leveraging variables that exist in this sports modality. A causal linkage diagram was elaborated based on the answers to the interviews, showing the systemic structure of the soccer (football) value chain in Brazil, whose premise it is to identify the existing circularities and the possibly existing points of leverage. The systemic structure pointed to the economic participation of soccer (football) in the Gross Domestic Product as a central variable to be leveraged, which tends to synthetize the results of the joint action of the actors in this chain. Furthermore, the variables that may limit or amplify the growth were identified. The systemic structure showed that the soccer (football) commodity chain is complex because of the great number of variables and interrelationships needed to represent its dynamics. The relationship between the actors also proved to be a factor of impact on economic and social development. 相似文献
32.
Núñez-Ríos Juan E. Sánchez-García Jacqueline Y. Tejeida-Padilla Ricardo 《Systemic Practice and Action Research》2020,33(5):527-559
Systemic Practice and Action Research - This article presents an approach to the problem that small and medium-sized Mexican lodging enterprises face regarding their ability to adapt to changes in... 相似文献
33.
Alföldi J Di Palma F Grabherr M Williams C Kong L Mauceli E Russell P Lowe CB Glor RE Jaffe JD Ray DA Boissinot S Shedlock AM Botka C Castoe TA Colbourne JK Fujita MK Moreno RG ten Hallers BF Haussler D Heger A Heiman D Janes DE Johnson J de Jong PJ Koriabine MY Lara M Novick PA Organ CL Peach SE Poe S Pollock DD de Queiroz K Sanger T Searle S Smith JD Smith Z Swofford R Turner-Maier J Wade J Young S Zadissa A Edwards SV Glenn TC Schneider CJ Losos JB Lander ES Breen M Ponting CP Lindblad-Toh K 《Nature》2011,477(7366):587-591
The evolution of the amniotic egg was one of the great evolutionary innovations in the history of life, freeing vertebrates from an obligatory connection to water and thus permitting the conquest of terrestrial environments. Among amniotes, genome sequences are available for mammals and birds, but not for non-avian reptiles. Here we report the genome sequence of the North American green anole lizard, Anolis carolinensis. We find that A. carolinensis microchromosomes are highly syntenic with chicken microchromosomes, yet do not exhibit the high GC and low repeat content that are characteristic of avian microchromosomes. Also, A. carolinensis mobile elements are very young and diverse-more so than in any other sequenced amniote genome. The GC content of this lizard genome is also unusual in its homogeneity, unlike the regionally variable GC content found in mammals and birds. We describe and assign sequence to the previously unknown A. carolinensis X chromosome. Comparative gene analysis shows that amniote egg proteins have evolved significantly more rapidly than other proteins. An anole phylogeny resolves basal branches to illuminate the history of their repeated adaptive radiations. 相似文献
34.
Verjovski-Almeida S DeMarco R Martins EA Guimarães PE Ojopi EP Paquola AC Piazza JP Nishiyama MY Kitajima JP Adamson RE Ashton PD Bonaldo MF Coulson PS Dillon GP Farias LP Gregorio SP Ho PL Leite RA Malaquias LC Marques RC Miyasato PA Nascimento AL Ohlweiler FP Reis EM Ribeiro MA Sá RG Stukart GC Soares MB Gargioni C Kawano T Rodrigues V Madeira AM Wilson RA Menck CF Setubal JC Leite LC Dias-Neto E 《Nature genetics》2003,35(2):148-157
Schistosoma mansoni is the primary causative agent of schistosomiasis, which affects 200 million individuals in 74 countries. We generated 163,000 expressed-sequence tags (ESTs) from normalized cDNA libraries from six selected developmental stages of the parasite, resulting in 31,000 assembled sequences and 92% sampling of an estimated 14,000 gene complement. By analyzing automated Gene Ontology assignments, we provide a detailed view of important S. mansoni biological systems, including characterization of metazoa-specific and eukarya-conserved genes. Phylogenetic analysis suggests an early divergence from other metazoa. The data set provides insights into the molecular mechanisms of tissue organization, development, signaling, sexual dimorphism, host interactions and immune evasion and identifies novel proteins to be investigated as vaccine candidates and potential drug targets. 相似文献
35.
Fusion of bone-marrow-derived cells with Purkinje neurons, cardiomyocytes and hepatocytes 总被引:1,自引:0,他引:1
Alvarez-Dolado M Pardal R Garcia-Verdugo JM Fike JR Lee HO Pfeffer K Lois C Morrison SJ Alvarez-Buylla A 《Nature》2003,425(6961):968-973
Recent studies have suggested that bone marrow cells possess a broad differentiation potential, being able to form new liver cells, cardiomyocytes and neurons. Several groups have attributed this apparent plasticity to 'transdifferentiation'. Others, however, have suggested that cell fusion could explain these results. Using a simple method based on Cre/lox recombination to detect cell fusion events, we demonstrate that bone-marrow-derived cells (BMDCs) fuse spontaneously with neural progenitors in vitro. Furthermore, bone marrow transplantation demonstrates that BMDCs fuse in vivo with hepatocytes in liver, Purkinje neurons in the brain and cardiac muscle in the heart, resulting in the formation of multinucleated cells. No evidence of transdifferentiation without fusion was observed in these tissues. These observations provide the first in vivo evidence for cell fusion of BMDCs with neurons and cardiomyocytes, raising the possibility that cell fusion may contribute to the development or maintenance of these key cell types. 相似文献
36.
The study of fossilized footprints and tracks of dinosaurs and other vertebrates has provided insight into the origin, evolution and extinction of several major groups and their behaviour; it has also been an important complement to their body fossil record. The known history of birds starts in the Late Jurassic epoch (around 150 Myr ago) with the record of Archaeopteryx, whereas the coelurosaurian ancestors of the birds date back to the Early Jurassic. The hind limbs of Late Triassic epoch theropods lack osteological evidence for an avian reversed hallux and also display other functional differences from birds. Previous references to suggested Late Triassic to Early Jurassic bird-like footprints have been reinterpreted as produced by non-avian dinosaurs having a high angle between digits II and IV and in all cases their avian affinities have been challenged. Here we describe well-preserved and abundant footprints with clearly avian characters from a Late Triassic redbed sequence of Argentina, at least 55 Myr before the first known skeletal record of birds. These footprints document the activities, in an environment interpreted as small ponds associated with ephemeral rivers, of an unknown group of Late Triassic theropods having some avian characters. 相似文献
37.
Ras proteins in the control of the cell cycle and cell differentiation 总被引:12,自引:0,他引:12
The Ras family of small GTPases includes three closely related proteins: H-, K-, and N-Ras. Ras proteins are involved in
the transduction of signals elicited by activated surface receptors, acting as key components by relaying signals downstream
through diverse pathways. Mutant, constitutively activated forms of Ras proteins are frequently found in cancer. While constitutive
Ras activation induces oncogenic-like transformation in immortalized fibroblasts, it causes growth arrest in primary vertebrate
cells. Induction of p53 and cyclin-dependent kinase inhibitors such as p15INK4b, p16INK4a, p19ARF, and p21WAF1 accounts for this response. Interestingly, while ras has usually been regarded as a transforming oncogene, the analysis of Ras function in most of the cellular systems studied
so far indicates that the promotion of differentiation is the most prominent effect of Ras. While in some cell types, particularly
muscle, Ras inhibits differentiation, in others such as neuronal, adipocytic, or myeloid cells, Ras induces differentiation,
in some cases accompanied by growth arrest. Several possible mechanisms for the pleiotropic effects of Ras in animal cells
are discussed.
Received 8 March 2000; received after revision 24 May 2000; accepted 24 May 2000 相似文献
38.
Alireza Noormohammadi Giuseppe Calculli Ricardo Gutierrez-Garcia Amirabbas Khodakarami Seda Koyuncu David Vilchez 《Cellular and molecular life sciences : CMLS》2018,75(2):275-290
Protein homeostasis, or proteostasis, is essential for cell function, development, and organismal viability. The composition of the proteome is adjusted to the specific requirements of a particular cell type and status. Moreover, multiple metabolic and environmental conditions challenge the integrity of the proteome. To maintain the quality of the proteome, the proteostasis network monitors proteins from their synthesis through their degradation. Whereas somatic stem cells lose their ability to maintain proteostasis with age, immortal pluripotent stem cells exhibit a stringent proteostasis network associated with their biological function and intrinsic characteristics. Moreover, growing evidence indicates that enhanced proteostasis mechanisms play a central role in immortality and cell fate decisions of pluripotent stem cells. Here, we will review new insights into the melding fields of proteostasis and pluripotency and their implications for the understanding of organismal development and survival. 相似文献
39.
Homozygous mutation of AURKC yields large-headed polyploid spermatozoa and causes male infertility 总被引:1,自引:0,他引:1
Dieterich K Soto Rifo R Faure AK Hennebicq S Ben Amar B Zahi M Perrin J Martinez D Sèle B Jouk PS Ohlmann T Rousseaux S Lunardi J Ray PF 《Nature genetics》2007,39(5):661-665
The World Health Organization conservatively estimates that 80 million people suffer from infertility worldwide. Male factors are believed to be responsible for 20-50% of all infertility cases, but microdeletions of the Y chromosome are the only genetic defects altering human spermatogenesis that have been reported repeatedly. We focused our work on infertile men with a normal somatic karyotype but typical spermatozoa mainly characterized by large heads, a variable number of tails and an increased chromosomal content (OMIM 243060). We performed a genome-wide microsatellite scan on ten infertile men presenting this characteristic phenotype. In all of these men, we identified a common region of homozygosity harboring the aurora kinase C gene (AURKC) with a single nucleotide deletion in the AURKC coding sequence. In addition, we show that this founder mutation results in premature termination of translation, yielding a truncated protein that lacks the kinase domain. We conclude that the absence of AURKC causes male infertility owing to the production of large-headed multiflagellar polyploid spermatozoa. 相似文献
40.
Hermann JC Marti-Arbona R Fedorov AA Fedorov E Almo SC Shoichet BK Raushel FM 《Nature》2007,448(7155):775-779
With many genomes sequenced, a pressing challenge in biology is predicting the function of the proteins that the genes encode. When proteins are unrelated to others of known activity, bioinformatics inference for function becomes problematic. It would thus be useful to interrogate protein structures for function directly. Here, we predict the function of an enzyme of unknown activity, Tm0936 from Thermotoga maritima, by docking high-energy intermediate forms of thousands of candidate metabolites. The docking hit list was dominated by adenine analogues, which appeared to undergo C6-deamination. Four of these, including 5-methylthioadenosine and S-adenosylhomocysteine (SAH), were tested as substrates, and three had substantial catalytic rate constants (10(5) M(-1 )s(-1)). The X-ray crystal structure of the complex between Tm0936 and the product resulting from the deamination of SAH, S-inosylhomocysteine, was determined, and it corresponded closely to the predicted structure. The deaminated products can be further metabolized by T. maritima in a previously uncharacterized SAH degradation pathway. Structure-based docking with high-energy forms of potential substrates may be a useful tool to annotate enzymes for function. 相似文献