检索结果-南通市图书馆

A Model System of Development Regulated by the Long-distance Transport of mRNA

在线全文

学校读者我要写书评

暂无评论

j.urnal of Integrative Plant Biology 2010年第1期52卷 40-52页

作者： David j. Hannapel Plant Biology Maj.r 253 Horticulture Hall Iowa State University

BELl-like transcription factors are ubiquitous in plants and interact with KNOTTEDI-types to regulate numerous developmental processes. In potato, the RNA of several BELl-like transcription factors has been identified in phloem cells. One of these, StBEL5, and its Knox protein partner regulate tuber formation by targeting genes that control growth. RNA detection methods and grafting experiments demonstrated that StBEL5 transcripts move across a graft union to localize in stolon tips, the site of tuber induction. This movement of RNA originates in source leaf veins and petioles and is induced by a short-day photoperiod, regulated by the untranslated regions, and correlated with enhanced tuber production. Addition of the StBEL5 untranslated regions to another *** mRNA resulted in its preferential transport to stolon tips leading to increased tuber production. Upon fusion of the untranslated regions of StBEL5 to a β-glucuronidase marker, translation in tobacco protoplasts was repressed by those constructs containing the 3＇ untranslated sequence. The untranslated regions of the StBEL5 mRNA are involved in mediating its long-distance transport and in controlling translation. The 3＇ untranslated sequence contains an abundance of conserved motifs that may serve as binding motifs for RNA-binding proteins. Because of their presence in the phloem sieve tube system, their unique untranslated region sequences and their diverse RNA accumulation patterns, the family of BEL1-like RNAs from potato represents a valuable model for studying the long-distance transport of full-length mRNAs and their role in development.

关键词： BEL A Model System of Development Regulated by the Long-distance Transport of mRNA Long

Out-of-core clustering of volumetric datasets

在线全文

学校读者我要写书评

暂无评论

j.urnal of Zhej.ang University-Science A(Applied Physics & Engineering) 2006年第7期7卷 1134-1140页

作者： GRANBERG Carl j. Department of Computing Curtin University of Technology Perth Australia

In this paper we present a novel method for dividing and clustering large volumetric scalar out-of-core datasets. This work is based on the Ordered Cluster Binary Tree (OCBT) structure created using a top-down or divisive clustering method. The OCBT structure allows fast and efficient sub volume queries to be made in combination with level of detail (LOD) queries of the tree. The initial partitioning of the large out-of-core dataset is done by using non-axis aligned planes calculated using Principal Component Analysis (PCA). A hybrid OCBT structure is also proposed where an in-core cluster binary tree is combined with a large out-of-core file.

关键词： Out-of-core clustering Hybrid rendering Scientific visualization

A simple model for reconstructing geomagnetic field intensity with (10)~Be production rate and its application in Loess studies

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2008年第6期51卷 855-861页

作者： j. Warren BECK NSF-AMS Laboratory University of Arizona

A simple model for reconstructing the paleomagnetic field intensity with (10)~Be production rate was used for the first time in Loess (10)~Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation effects on loess (10)~Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic intensity curve from Loess (10)~Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the (10)~Be paleo- intensity curve and the future direction of loess (10)~Be tracing studies. Results show the irregular vari-ability of the East Asian monsoon precipitation in Loess Plateau is the main cause that has resulted in the ambiguity of the geomagnetic modulation of the (10)~Be record in the loess, and the intrinsic source component of the loess (10)~Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the 'quasi-homogeneous distribution' manner.

关键词： (10)~Be LGM geomagnetic excursion paleointensity quasi-homogeneous distribution

Expanding the phenotypic plasticity paradigm to broader views of trait space and ecological function

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2016年第5期62卷 463-473页

作者： Thomas j. DEWITT Department of Wildlife & Fisheries Sciences Texas A&M University College Station TX 77843-2258 USA

Foundational concepts of trait spaces, including phenotypic plasticity and function of traits, should be expanded and better integrated with ecological theory. This article addresses two areas where plasticity theory can become further integrated with ecological, evolutionary, and developmental thinking. First is the idea that not only trait means within environments and plasticity of trait means across environments is optimized by selection, but that the entire shape of phenotype distributions such as variance or skew should be optimized within and across environments. In order for trait distribution shape to evolve into adaptations, there must be a genetic basis for and selection upon variation in distribution shapes and their plasticities. I present published and new data demonstrating genetic control and selection for higher moments of phenotype distributions; though, plasticity in these values has not yet been tested. Genetic control of phenotype distribution moments is shown for Neurospora crassa ascospore size and shape. Selection on trait distribution moments is shown for Eurosta solidaginis gall size. Second, there is a tradition in modeling plasti- city as an adaptive strategy that pits it as an alternative to ecological specialization or generaliza- tion. However, these strategies need not be considered alternatives. Rather, with environmental fluctuation within generations plasticity may produce additive or non-additive intermediate （gener- alist） phenotypes, or something new altogether. I present published and new data on the snail Physa virgata and fish Gambusia affinis that show plasticity produces partly intermediate （general- ist） and partly unique phenotypic elements in mixed and fluctuating environments. Plasticity can thus be viewed in the context of a broader trait space and as having broader ecological roles than currently is conceived.

关键词： genetics of trait distributions multi-moment reaction norms non-additive plasticity off-plane phenotypes probabilisticoptimization selection on trait distributions specialists and generalists.

Integrating ancient patterns and current dynamics of insect-plant interactions＂ Taxonomic and geographic variation in herbivore specialization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2010年第6期17卷 471-507页

作者： j. Mark Scriber Department of Entomology Michigan State University East Lansing Michigan McGuire center for Lepidoptera and Biodiversity Florida Museum of Natural History University of Florida Gainesville Florida USA

The search for pattern in the ecology and evolutionary biology of insect-plant associations has fascinated biologists for centuries. High levels of tropical （tow-latitude） plant and insect diversity relative to poleward latitudes and the disproportionate abundance of host-specialized insect herbivores have been noted. This review addresses several aspects of local insect specialization, host use abilities （and loss of these abilities with specialization）, host-associated evolutionary divergence, and ecological （including ＂hybrid＂） speciation, with special reference to the generation of biodiversity and the geographic and taxonomic identification of ＂species borders＂ for swallowtail butterflies （Papilionidae）. From ancient phytochemically defined angiosperm affiliations that trace back millions of years to recent and very local specialized populations, the Papilionidae （swallowtail butterflies） have provided a model for enhanced tmderstanding of localized ecological patterns and genetically based evolutionary processes. They have served as a useful group for evaluating the feeding specialization/physiological efficiency hypothesis. They have shown how the abiotic （thermal） environment interacts with host nutritional suitability to generate ＂voltinisrn/suitability＂ gradients in specialization or preference latitudinally, and geographical mosaics locally. Several studies reviewed here suggest strongly that the oscillation hypothesis for speciation does have considerable merit, but at the same time, some species-level host specializations may lead to evolutionary dead-ends, especially with rapid environmental/habitat changes involving their host plants. Latitudinal gradients in species richness and degree of herbivore feeding specialization have been impacted by recent developments in ecological genetics and evolutionary ecology. Localized insect- plant associations that span the biospectrum from polyphenisms, polymorphisms, biotypes, demes, host races, to cryptic speci

关键词： evolutionary dead-ends key innovations latitudinal gradients oscillation hypothesis of speciation polyspecialists preference/performance specialization/physiological efficiency hypothesis voltinism-suitability hypothesis

Semen analysis in 21st century medicine： the need for sperm function testing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian j.urnal of Andrology 2010年第1期12卷 64-70页

作者： Dolores j. Lamb Scott Department of Urology and the Department of Molecular and cellular Biology Baylor College of MedicineHouston TX 77030 USA

Sperm function testing, once commonly performed for the infertile couple before employing assisted reproductive technology （ART）, has fallen out of favour in many reproductive medicine centers throughout the world. Indeed, the most recent addition of the ＇World Health Organisation （WHO） Laboratory Manual for the Examination and Processing of Hu- man Semen＇ now groups many of these procedures into a section termed Research Procedures. In large part, this reflects the current clinical practice of bypassing the in-depth evaluation of the male partner, while assuming that if a spermatozoon can be found for intracytoplasmic sperm inj.ction （ICSI）, it must be a healthy cell capable of achieving fertilization. Never- theless, sperm function testing can provide valuable clinical insights into defects causing male infertility. Admittedly, in some cases, functional sperm deficiencies can be overcome using an ART. In other cases, couples will be empowered by the knowledge of the cause of their infertility, and for some couples, perhaps even the likelihood of ICSI success （relative to the spermatozoa）. The knowledge allows them to make truly informed reproductive decisions, including （perhaps） the de- cision to seek donor insemination, to adopt or to remain childless. Knowledge of the cause of their infertility may provide closure for couples and a sense of confidence regarding their choice of reproductive treatment.

关键词： semen analysis sperm function tests

Advances in newly developing therapy for chronic hepatitis C virus infection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Medicine 2014年第2期8卷 166-174页

作者： Paul j. Pockros Division of Gastro/Hepatology Scripps Clinic 10666 N Torrey Pines Road N203 La Jolla CA 92067 USA

Chronic hepatitis C virus （HCV） infection afflicts a reported 170 million people worldwide and is often complicated by cirrhosis and hepatocellular carcinoma. Morbidity and mortality are decreased with the successful treatment of chronic HCV infection. Increased understanding of the HCV has allowed further development of new direct-acting antiviral （DAA） agents against the HCV and has also allowed the development of IFN-free oral treatment regimens. In late 2013 the first nucleotide polymerase inhibitor regimen with RBV alone for genotypes 2/3 and in combination with a 12-week regimen of peG-IFN ＋ RBV for genotypes 1, 4 was approved for use in the US. A number of promising new DAA regimens which are IFN-free are in phase 3 development and the first will likely be approved for use in the US in 2014. The currently approved regimens are discussed in detail and currently available data on future regimens are reviewed herein.

关键词： direct-acting antiviral (DAA) nucleotide polymerase inhibitors protease inhibitors

Humid Little Ice Age in arid central Asia documented by Bosten Lake, Xinj.ang, China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2006年第12期49卷 1280-1290页

作者： j. A. Holmes ECRC Department of Geography University College London

Short sediment cores retrieved from Bosten Lake, the largest inland freshwater lake in China, were used to explore humidity and precipitation variations in arid central Asia during the past millennium. The chronology of the cores was established using 137Cs, 210Pb and AMS 14C dating re- sults. Multi-proxy high-resolution analysis, including pollen ratios of Artemisia and Chenopodiaceae (A/C), carbonate content and grain size, indicates that the climate during the past millennium can be divided into three stages: a dry climate between 1000―1500 AD, a humid climate during the Little Ice Age (LIA) (c. 1500―1900 AD), and a warm dry period after 1900 AD. On centennial timescales, the climate change in northwestern China during the past 1000 years is characterized by oscillations between warm-dry and cold-humid climate conditions. All the proxies changed significantly and indi- cate increased precipitation during the LIA, including increased pollen A/C ratios and pollen concen- trations, decreased carbonate content and increased grain size. The humid period during the LIA re- corded by the Bosten Lake sediments is representative of arid central Asia and is supported by nu- merous records from other sites. During the LIA, the water runoff into the Keriya River and Tarim River in the Tarim Basin increased, while the ice accumulation in the Guliya ice core increased. Additionally, the lake levels of the Aral and Caspian Sea also rose, while tree-ring analysis indicates that precipita- tion increased. We hypothesize that both the lower temperature within China and the negative anomalies of North Atlantic Oscillation (NAO) during this period may have contributed to the humid climate within this area during LIA.

关键词： multiproxy analyses,Bosten Lake,humid Little Ice Age,past millennium,arid central Asia.

MODELING THE KNOWLEDGE CREATION PROceSS OF GRADUATE RESEARCH

在线全文

学校读者我要写书评

暂无评论

j.urnal of Systems Science and Systems Engineering 2018年第6期27卷 790-809页

作者： j. Sun j. Tian V.N. Huynh Y. Nakamori School of Knowledge Science Japan Advanced lnstitute of Science and Technology lshikawa Japan School of Computer Science and Technology Wuhan University of Technology Wuhan China

Graduate students who are beginning academic research want to learn how to create and verify new knowledge in their research. Their supervisors, on the other hand, are seeking appropriate research environments including effective research guidance methods. In order to meet these demands, this paper proposes a knowledge creation model that supports the obj.ctives of both graduate students and their supervisors. This is an academic knowledge creation model for individuals supported by a group and its origin can be traced back to a famous organizational knowledge creation model. Since this type of model is constructed from empirical knowledge, it is not easy to prove its obj.ctive significance. But, this paper tries to show the effectiveness of the proposed model as an initial stage of model validation based on a questionnaire survey of students in a graduate school in China.

关键词： Knowledge creation model graduate students research ability research environment