通过对广西来宾菊花石的野外工作及其形貌观察、电子探针成分分析、偏光显微镜鉴定, 阐明了菊花石(chrysanthem um stone)的分布和形貌特征及其后生变化规律,认为菊花石主要由天青石、方解石和玉髓三种矿物组成。天青石(SrSO4)为原生矿...通过对广西来宾菊花石的野外工作及其形貌观察、电子探针成分分析、偏光显微镜鉴定, 阐明了菊花石(chrysanthem um stone)的分布和形貌特征及其后生变化规律,认为菊花石主要由天青石、方解石和玉髓三种矿物组成。天青石(SrSO4)为原生矿物,后经碳酸盐化,继而硅化形成方解石和玉髓。展开更多
Epigenetics of human cancer becomes an area of emerging research direction due to a growing understanding ofspecific epigenetic pathways and rapid development of detection technologies. Aberrant promoter hypermethylat...Epigenetics of human cancer becomes an area of emerging research direction due to a growing understanding ofspecific epigenetic pathways and rapid development of detection technologies. Aberrant promoter hypermethylation is aprevalent phenonmena in human cancers. Tumor suppressor genes are often hypermethylated due to the increasedactivity or deregulation of DNMTs. Increasing evidence also reveals that viral genes are one of the key players inregulating DNA methylation. In this review, we will focus on hypermethylation and tumor suppressor gene silencing andthe signal pathways that are involved, particularly in cancers closely associated with the hepatitis B virus, simian virus40 (SV40), and Epstein-Barr virus. In addition, we will discuss current technologies for genome-wide detection ofepigenetically regulated targets, which allow for systematic DNA hypermethylation analysis. The study of epigeneticchanges should provide a global view of gene profile in cancer, and epigenetic markers could be used for early detection,prognosis, and therapy of cancer.展开更多
Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical fo...Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.展开更多
Most seabird species display colonial behavior during the breeding period which implies that food resources around breeding sites can easily go depleted. Seabirds need to both reach profitable areas, which can be loca...Most seabird species display colonial behavior during the breeding period which implies that food resources around breeding sites can easily go depleted. Seabirds need to both reach profitable areas, which can be located far from the colony, and return to the colony regularly. In this context, flexibility in movement behavior may be crucial for breeding success. During chick-rearing, Procellariformes species can alternate short trips lasting 1-4 days for chick provisioning with longer trips for self-provisioning in what has been called a dual-foraging strategy. We analyzed foraging trips from 136 Scopoli＇s shearwaters from three Mediterranean colonies tracked with GPS during 6 chick-rearing seasons to assess whether the adoption of a dual fo- raging strategy depends on the quality of habitat surrounding the colony. We found a marked dual-foraging strategy only in birds from the Linosa colony which was the largest colony in terms of breeding pairs and was characterized by having a lower marine habitat quality. Birds from this colony performed foraging trips that extended up to 369 km from the nest and lasted more than 10 days. In general, the decision to perform long lasting trips was triggered by lower values of primary production and higher offspring weight. Contrary to expectation, the decision to feed far from the colony was not related to the parents＇ weight. At the same time, despite the higher productivity offered by distant areas, the higher proportion of long trips performed by birds breeding in poor areas was not sufficient to maintain the same body mass as the ones breeding in richer areas [Current Zoology 60 （5）： 622-630, 2014].展开更多
文摘Epigenetics of human cancer becomes an area of emerging research direction due to a growing understanding ofspecific epigenetic pathways and rapid development of detection technologies. Aberrant promoter hypermethylation is aprevalent phenonmena in human cancers. Tumor suppressor genes are often hypermethylated due to the increasedactivity or deregulation of DNMTs. Increasing evidence also reveals that viral genes are one of the key players inregulating DNA methylation. In this review, we will focus on hypermethylation and tumor suppressor gene silencing andthe signal pathways that are involved, particularly in cancers closely associated with the hepatitis B virus, simian virus40 (SV40), and Epstein-Barr virus. In addition, we will discuss current technologies for genome-wide detection ofepigenetically regulated targets, which allow for systematic DNA hypermethylation analysis. The study of epigeneticchanges should provide a global view of gene profile in cancer, and epigenetic markers could be used for early detection,prognosis, and therapy of cancer.
文摘Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.
文摘Most seabird species display colonial behavior during the breeding period which implies that food resources around breeding sites can easily go depleted. Seabirds need to both reach profitable areas, which can be located far from the colony, and return to the colony regularly. In this context, flexibility in movement behavior may be crucial for breeding success. During chick-rearing, Procellariformes species can alternate short trips lasting 1-4 days for chick provisioning with longer trips for self-provisioning in what has been called a dual-foraging strategy. We analyzed foraging trips from 136 Scopoli＇s shearwaters from three Mediterranean colonies tracked with GPS during 6 chick-rearing seasons to assess whether the adoption of a dual fo- raging strategy depends on the quality of habitat surrounding the colony. We found a marked dual-foraging strategy only in birds from the Linosa colony which was the largest colony in terms of breeding pairs and was characterized by having a lower marine habitat quality. Birds from this colony performed foraging trips that extended up to 369 km from the nest and lasted more than 10 days. In general, the decision to perform long lasting trips was triggered by lower values of primary production and higher offspring weight. Contrary to expectation, the decision to feed far from the colony was not related to the parents＇ weight. At the same time, despite the higher productivity offered by distant areas, the higher proportion of long trips performed by birds breeding in poor areas was not sufficient to maintain the same body mass as the ones breeding in richer areas [Current Zoology 60 （5）： 622-630, 2014].
