95 research outputs found
Average mass of seeds encountered by foraging dabbling ducks in Western Europe
Many
dabbling ducks Anas spp. are largely granivorous, consuming a variety of seeds
chiefly from aquatic plants. To assess the relative value and carrying capacity
of wetlands for dabbling ducks, species-specific information about seed mass is
needed, but it is still largely missing or scattered in the literature. By
combining weights of seeds collected in the field with a literature review, we
provide a reference table for seed mass of 200 western European plant taxa
frequently encountered by foraging dabbling ducks. Seeds collected in the field
were sampled in microhabitats and at depths at which ducks were observed to
forage, and study sites represent wintering, staging as well as breeding areas
within a flyway in western Europe. When combined with calorimetric data, the
present reference table will aid managers and scientists in assessing the
importance of seed food resources at different sites and during different parts
of the annual cycle.</p
Transcription Profiling of Epstein-Barr Virus Nuclear Antigen (EBNA)-1 Expressing Cells Suggests Targeting of Chromatin Remodeling Complexes
The Epstein-Barr virus (EBV) encoded nuclear antigen (EBNA)-1 regulates virus replication and transcription, and participates in the remodeling of the cellular environment that accompanies EBV induced B-cell immortalization and malignant transformation. The putative cellular targets of these effects of EBNA-1 are largely unknown. To address this issue we have profiled the transcriptional changes induced by short- and long-term expression of EBNA-1 in the EBV negative B-cell lymphoma BJAB. Three hundred and nineteen cellular genes were regulated in a conditional transfectant shortly after EBNA-1 induction while a ten fold higher number of genes was regulated upon continuous EBNA-1 expression. Promoter analysis of the differentially regulated genes demonstrated a significant enrichment of putative EBNA-1 binding sites suggesting that EBNA-1 may directly influence the transcription of a subset of genes. Gene ontology analysis of forty seven genes that were consistently regulated independently on the time of EBNA-1 expression revealed an unexpected enrichment of genes involved in the maintenance of chromatin architecture. The interaction network of the affected gene products suggests that EBNA-1 may promote a broad rearrangement of the cellular transcription landscape by altering the expression of key components of chromatin remodeling complexes
Indirect interactions in the High Arctic
Peer reviewe
Substrate-specific regulation of RNA deadenylation in Xenopus embryo and activated egg extracts.
The poly(A) tail of mRNAs plays an important role in translational control. In Xenopus laevis matured oocytes, maternal mRNAs that contain a cytoplasmic polyadenylation element (CPE) are polyadenylated, whereas CPE deficient mRNAs are deadenylated by a default process. Eg mRNAs are maternal transcripts that are poly(A)+ in matured oocytes and rapidly deadenylated after fertilization. This post-fertilization deadenylation of Eg mRNAs requires specific sequence information. Such a deadenylation element has been identified previously in the 3'UTR of Eg2 mRNA. In this study, we show that cell-free extracts made from embryos or activated eggs contain two kinetically distinct deadenylation activities, with different substrate specificities. One, responsible for the slow deadenylation of RNAs that are devoid of a functional CPE, has the characteristics of a default PAN activity. The other effectuates the rapid deadenylation of RNAs containing a deadenylation element. The in vitro system described here will allow the characterization of factors controlling the deadenylation of Eg mRNAs in embryos
Vimentin gene: expression in human lymphocytes and in Burkitt's lymphoma cells.
We have isolated a human genomic clone for the intermediate filament subunit vimentin with a DNA probe encoding chicken vimentin. We show that the gene for this protein exists as a single copy in the haploid human genome and is transcribed into one mature RNA species of 2 kb. In vitro translation of poly(A)+ mRNA in a rabbit reticulocyte cell-free system showed that vimentin is a major product of RNA from normal lymphocytes but not of RNA extracted from Burkitt cells. 2-kb vimentin mRNA can be detected with a DNA probe in normal lymphocytes and in fibroblasts, but not in cell lines derived from Burkitt's lymphoma (JI, JBL2, BJAB, DAUDI). The abundance of vimentin mRNA is correlated with the quantity of vimentin present in the cells, suggesting that the level of expression is regulated by the abundance of mRNA. The half-lives of vimentin mRNA were found identical in both fibroblasts and lymphocytes and belong to the class of stable mRNA
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