Cancer is the second major threat to human society and one of the main challenges facing healthcare systems. One of the main problems of cancer care is the metastases of cancer cells that cause 90% of deaths due to cancer. Multiple molecular mechanisms are involved in cancer cell metastasis. Therefore, a better understanding of these molecular mechanisms is necessary for designing restrictive strategies against cancer cell metastasis. Accumulating data suggests that MicroRNAs (miRNAs) are involved in metastasis and invasion of human tumors through regulating multiple genes expression levels that are involved in molecular mechanisms of metastasis. The goal of this review is to present the molecular pathways by which the miR 200 family manifests its effects on EMT, cancer stem cells, angiogenesis, anoikis, and the effects of tumor cell metastases.
Methods
A detailed literature search was conducted to find information about the role of the miR-200 family in the processes involved in metastasis in various databases.
Results
Numerous lines of evidence revealed an association between the mir-200 family and metastasis of human tumors by impressing processes such as cancer stem cells, EMT, angiogenesis, and anoikis.
Conclusions
Understanding the molecular mechanisms associated with metastasis in which the miR-200 family is involved can be effective in treating metastatic cancers.
Even with global support for tiger (Panthera tigris) conservation their survival is threatened by poaching, habitat loss and isolation. Currently about 3,000 wild tigers persist in small fragmented populations within seven percent of their historic range. Identifying and securing habitat linkages that connect source populations for maintaining landscape-level gene flow is an important long-term conservation strategy for endangered carnivores. However, habitat corridors that link regional tiger populations are often lost to development projects due to lack of objective evidence on their importance. Here, we use individual based genetic analysis in combination with landscape permeability models to identify and prioritize movement corridors across seven tiger populations within the Central Indian Landscape. By using a panel of 11 microsatellites we identified 169 individual tigers from 587 scat and 17 tissue samples. We detected four genetic clusters within Central India with limited gene flow among three of them. Bayesian and likelihood analyses identified 17 tigers as having recent immigrant ancestry. Spatially explicit tiger occupancy obtained from extensive landscape-scale surveys across 76,913 km2 of forest habitat was found to be only 21,290 km2. After accounting for detection bias, the covariates that best explained tiger occupancy were large, remote, dense forest patches; large ungulate abundance, and low human footprint. We used tiger occupancy probability to parameterize habitat permeability for modeling habitat linkages using least-cost and circuit theory pathway analyses. Pairwise genetic differences (FST) between populations were better explained by modeled linkage costs (r>0.5, p<0.05) compared to Euclidean distances, which was in consonance with observed habitat fragmentation. The results of our study highlight that many corridors may still be functional as there is evidence of contemporary migration. Conservation efforts should provide legal status to corridors, use smart green infrastructure to mitigate development impacts, and restore habitats where connectivity has been lost. 相似文献
This paper reports the conversion of cis-[14C]phytofluene to trans-[14C|phytofluene and the conversion of the latter compound to trans-ζ-[14C]carotene by a soluble enzyme system obtained from the plastids of red tomato fruits. Each of these radioactive compounds was also converted to labeled neurosporene, lycopenc, α-carotene, and β-carotene by the same enzyme system. The incorporation of each substrate into more unsaturated carotenes was carried out under nitrogen at pH 7.5–8.2 (borate buffer), at 25 °C in the dark.Proof of the formation of the above carotenes from each of the three radioactive substrates was demonstrated by cochromatography with authentic nonradioactive carotenes on an alumina chromatographic column. A close correspondence between radioactivity and light absorbance for each carotene was observed. Confirmation of these conversions was achieved by cochromatography with authentic samples on thinlayer plates. Final proof for the formation of the acyclic and cyclic carotenes from the above radioactive substrates was obtained by gas-liquid chromatography of the hydrogenated products. Coincidence between mass and radioactivity was observed.Maximum conversion of cis- and trans-phytofluenes to more unsaturated carotenes by the red tomato fruit enzyme system appears to be dependent upon the presence of NADP+, FAD, and Tween 80. The formation of the carotenes is also increased in the presence of Mg2+ or Mn2+ ions. 相似文献
Aquatic macrophytes formed dense beds in fallow areas during the four and a half months of the flood season in all but one deepwater rice-growing location in Bangladesh; these included several types of life-form, but the fine-leaved species, Myriophyllum sp., Najas indica, Utricularia stellaris were often especially abundant. The same species grew inside deepwater rice fields, but at much lower densities. A similar contrast occurred for the algae, although deepwater rice often developed dense masses of epiphytes on aquatic roots, stems and leaf sheaths, when plants were growing in isolated, well-illuminated situations.
Two widespread algae, Aulosira fertilissima and Scytonema mirabile, were equally successful on soil in the period prior to the arrival of floodwaters and floating on the surface of the water during the flood season. Other species common during the flood season differed from those common on soil.
Most blue-green algae inside deepwater rice fields were heterocystous; the only species not so, but forming distinct colonies, was Aphanothece stagnina. However only non-heterocystous forms were found at one location in south Bangladesh (Phaltita) and a change from heterocystous to non-heterocystous forms was noted at the main research site (near Sonargaon) during late September in at least one year. The water column at the former was almost entirely anoxic, while the change at the latter occurred at a time when the water sometimes became anoxic during the night. It is suggested that differences in ability to tolerate anoxic periods may be a key factor in determining the success of the algal and vascular plant species in the different micro-habitats within these DWR-growing areas.
Although diatoms were quantitatively only a minor component of the algal biomass, they became more frequent later in the season when the water became microaerobic or anoxic for part of the day. Navicula confervacea was overall the most abundant species at the two main research locations.
Aquatic macrophytes formed dense beds in fallow areas during the four and a half months of the flood season in all but one deepwater rice-growing location in Bangladesh; these included several types of life-form, but the fine-leaved species, Myriophyllum sp., Najas indica, Utricularia stellaris were often especially abundant. The same species grew inside deepwater rice fields, but at much lower densities. A similar contrast occurred for the algae, although deepwater rice often developed dense masses of epiphytes on aquatic roots, stems and leaf sheaths, when plants were growing in isolated, well-illuminated situations.
Two widespread algae, Aulosira fertilissima and Scytonema mirabile, were equally successful on soil in the period prior to the arrival of floodwaters and floating on the surface of the water during the flood season. Other species common during the flood season differed from those common on soil.
Most blue-green algae inside deepwater rice fields were heterocystous; the only species not so, but forming distinct colonies, was Aphanothece stagnina. However only non-heterocystous forms were found at one location in south Bangladesh (Phaltita) and a change from heterocystous to non-heterocystous forms was noted at the main research site (near Sonargaon) during late September in at least one year. The water column at the former was almost entirely anoxic, while the change at the latter occurred at a time when the water sometimes became anoxic during the night. It is suggested that differences in ability to tolerate anoxic periods may be a key factor in determining the success of the algal and vascular plant species in the different micro-habitats within these DWR-growing areas.
Although diatoms were quantitatively only a minor component of the algal biomass, they became more frequent later in the season when the water became microaerobic or anoxic for part of the day. Navicula confervacea was overall the most abundant species at the two main research locations.
Eight anionic disaccharide precursors of lipid A accumulate at 42 degrees C in 3-deoxy-D-manno-octulosonic acid-deficient temperature-sensitive mutants of Salmonella typhimurium. These compounds comprise a series of lipids based on the minimal structure, O-[2-amino-2-deoxy-N2,O3-bis(3-hydroxytetradecanoyl)-beta-D-glucopyranos yl] -(1----6)-2-amino-2-deoxy-N2, O3-bis(3-hydroxytetradecanoyl)-alpha-D-glucopyranose 1,4'- bisphosphate (designated lipid IVA) that differ from each other by the presence of an additional phosphoethanolamine moiety (IIIA), or an aminodeoxypentose moiety (IIA), or both (IA). A homologous set of metabolites is further derivatized with a palmitoyl function; these are designated IVB, IIIB, IIB, and IB (Raetz, C. R. H., Purcell, S., Meyer, M. V., Qureshi, N., and Takayama, K. (1985) J. Biol. Chem. 260, 16080-16088). The attachment of the palmitoyl moiety, known to be on the reducing terminal GlcN residue by mass spectrometry, was determined to be O-beta of the N2-linked beta-hydroxymyristoyl group of that residue of IVB by 13C NMR and two-dimensional 1H chemical shift correlation spectroscopy experiments. 31P NMR indicated the presence of diphosphodiester moieties in IIIA, IIIB, and IA and monophosphodiester moieties in IIA and IA. Selective 1H decoupling of the 31P spectrum of IIIA demonstrated that the O-diphosphoethanolamine moiety is attached to the O4' position in IIIA. On the basis of the observed 31P chemical shifts it was concluded that the aminodeoxypentose is located at position 1 in IIA and IA, while diphosphoethanolamine is most likely located at O-4' in IA and IIIB, as in IIIA. 相似文献
Summary In an attempt to analyse long-term response in finite dioecious populations, selection processes are simulated on a computer with situations of parental population size, linkages between loci, selection intensity, and heritability, specified in a 34 factorial design. A diploid polygenic system of 40 loci on 4 chromosomes is considered for additive genes. Linkage levels are specified as free recombinations, adjacent loci 5 map units apart, and as clusters on chromosomes with a distance of only .5 units between adjacent loci. Parental populations of 8, 16, and 64, truncation selection of 1/2, 1/4, and 1/8 of the progeny each generation, and initial heritability of 1, 1/3, and 1/9 are simulated for various populations.For these populations, which are initially samples from a theoreticalHardy-Weinberg situation, it is shown that an initial linear phase of response, which may last for only 2 or 3 generations in some cases, depends on the intensity of selection alone. The effects and interactions of all the above factors on the curvilinearity of response in later generations are analysed. It appears that linkages between loci have a strong influence in reducing the rate of response and the total response. In the extreme cases of gene clusters in a parental population size of 8 with low heritability, truncation selection is relatively almost completely ineffective in causing change in the mean over generations. The effect of tight linkage is also exhibited in causing more reduction in genotypic variance than can be accounted for by corresponding response.The depressing effect of finiteness of population size on the rate of response and the total response appears to increase in geometric proportion with linkages between loci. The number of generations to fixation appears to be reduced in a similar manner. A strong interaction between population size and linkage is thereby found in various analyses. With parental populations as large as 64, linkage effects on response are negligible when recombinations between adjacent loci are .05 or more. In such situations there is a slower rate of response in later generations with linkage but the total response attained and the rate of fixation of inferior genes is about the same as for free recombinations. Increase in the intensity of selection appears to augment the effects of linkage in reducing the rate of response in later generations. This type of interaction is attributed to the accumulation of gametic disequilibria due to selection which are retained in the population over generations with linkage.
Zusammenfassung In der Absicht, das Verhalten einer begrenzten diözischen Population über einen langen Zeitraum zu analysicren, wurden Selektionsvorgänge auf einem Computer simuliert. Hierbei wurden die Größe der Elterpopulation, die Koppelung zwischen den Loci, die Selektionsintensität und die Heritabilität in einem 34-faktoriellen Versuch variiert. Es wird ein diploides polygenes System mit vierzig Loci auf vier Chromosomen mit additiver Genwirkung zugrunde gelegt. Für die Koppelungsbeziehungen werden freie Rekombination, ein Abstand von fünf Rekombinationseinheiten zwischen benachbarten Loci und die Bildung von Genclustern auf den Chromosomen mit jeweils nur 0,5Morgan-Einheiten Abstand zwischen benachbarten Loci angenommen. Es werden elterliche Populationen des Umfanges 8, 16 und 64, trunkierende (stutzende) Selektion mit einer Fraktion von 1/2, 1/4 und 1/8 der Nachkommen je Generation und eine ursprüngliche Heritabilität von 1, 1/3 und 1/9 für verschiedene Populationen simuliert.Für alle jene Populationen, die ursprünglich als Stichproben aus einer theoretischenHardy-Weinberg-Situation stammen, kann gezeigt werden, daß eine anfänglich lineare Phase der Reaktion, die in einigen Fällen nur über zwei bis drei Generationen anhält, allein von der Selektionsintensität abhängt. Die Wirkungen und Wechselwirkungen aller oben genannten Faktoren auf die Nichtlinearität der Reaktion in späteren Generationen wird untersucht. Es zeigt sich, daß Koppelung zwischen den Loci einen starken Einfluß auf die Reduktion der Reaktionsgeschwindigkeit und auf die Endreaktion ausübt. In dem extremen Fall der Gencluster in einer Ausgangspopulation des Umfanges 8 mit geringer Heritabilität ist die trunkierende Selektion hinsichtlich der Änderung des Mittels über Generationen hinweg praktisch völlig unwirksam. Die Wirkung enger Koppelung manifestiert sich außerdem in einer stärkeren Reduktion der genotypischen Varianz, als sie auf Grund der entsprechenden Reaktion erklärt werden kann. Der reduzierende Effekt der Begrenzung des Populationsumfanges auf die Reaktionsgeschwindigkeit und die Endreaktion erweist sich als geometrisch proportional zur Koppelung zwischen den Loci. Die Zahl der Generationen bis zur Fixierung wird in ähnlicher Weise reduziert. Hierbei wird eine starke Wechselwirkung zwischen der Populationsgröße und der Koppelung in den verschiedenen Untersuchungen beobachtet. Der Einfluß der Koppelung auf die Reaktion der Populationen kann vernachlässigt werden, wenn die elterliche Population den Umfang 64 hat und die Rekombination zwischen benachbarten Loci 0,05 übersteigt. In derartigen Situationen gibt es zwar eine langsamere Antwortrate in späteren Generationen mit Koppelung, jedoch ist die Endreaktion, die erreicht wird, und die Fixierungsrate überlegener Gene etwa die gleiche wie bei freier Spaltung. Eine Zunahme der Selektionsintensität scheint die Wirkung der Koppelung hinsichtlfch der Reduktion der Reaktionsgeschwindigkeit in späteren Generationen zu vergrößern. Dieser Typ der Wechselwirkung wird der Häufung gametischer Ungleichgewichte, die infolge der Selektion über Generationen in der Population erhalten werden, zugeschrieben.
Journal Paper No. 5872, Iowa Agriculture and Home Economics Experiment Station, Ames, supported by National Science Foundation Grant 19218 and National Institute of Health Grant GM-13827.On leave fromWest Pakistan Agricultural University Lyallpur.Statistical Laboratory and Department of Animal Science, respectively. 相似文献
