A linear sequence of extant families and genera of lycophytes and ferns

Throughout the history of the classification of extant ferns (monilophytes) and lycophytes, familial and generic concepts have been in great flux. For the organisation of lycophytes and ferns in herbaria, books, checklists, indices and spore banks and on the internet, this poses a problem, and a standardized linear sequence of these plants is therefore in great need. We provide here a linear classification to the extant lycophytes and ferns based on current phylogenetic knowledge; this provides a standardized guide for organisation of fern collections into a more natural sequence. Two new families, Diplaziopsidaceae and Rhachidosoraceae, are here introduced.Peer reviewe

Focal Spot, Winter 1983/84

https://digitalcommons.wustl.edu/focal_spot_archives/1036/thumbnail.jp

A Hessenberg-type algorithm for computing PageRank Problems

PageRank is a widespread model for analysing the relative relevance of nodes within large graphs arising in several applications. In the current paper, we present a cost-effective Hessenberg-type method built upon the Hessenberg process for the solution of difficult PageRank problems. The new method is very competitive with other popular algorithms in this field, such as Arnoldi-type methods, especially when the damping factor is close to 1 and the dimension of the search subspace is large. The convergence and the complexity of the proposed algorithm are investigated. Numerical experiments are reported to show the efficiency of the new solver for practical PageRank computations

The expression of PLK-1 in cervical carcinoma: a possible target for enhancing chemosensitivity

<p>Abstract</p> <p>Background</p> <p>Polo-like kinase-1 (PLK-1) is reported to be upregulated in a variety of human tumors and is implicated in cell proliferation and survival. However, its importance in cervical carcinoma has not yet been fully elucidated.</p> <p>Methods</p> <p>We examined PLK-1 expression in cervical carcinoma tissues using immunohistochemical staining. Furthermore, we blocked PLK-1 expression in HeLa cells using specific siRNA and detected the cell cycle, cell proliferation and chemosensitivity using western blotting, MTT and flow cytometry.</p> <p>Results</p> <p>We provide evidence that expression of PLK-1 exists in human cervical carcinoma tissues and establish an association with tumor size. Furthermore, we show that PLK-1 knockdown by transfection of siRNA induces accumulation of HeLa cells in the G2/M cell cycle phase and enhances cisplatin-induced apoptosis.</p> <p>Conclusion</p> <p>Our results indicate that PLK-1 production in HeLa cells might be critical in determining whether cells survive or undergo apoptosis. Therefore, targeting PLK-1 might be a promising strategy for enhancing sensitivity to chemotherapeutic reagents in cervical carcinoma.</p

Downregulation of KLF8 expression by shRNA induces inhibition of cell proliferation in CAL27 human oral cancer cells

Objectives: KLF8 is a member of KLF transcription factors which play an important tolr in oncogenesis. It is barely expressed in normal human epithelial cells but highly overexpressed in several types of human cancer cell lines. In the present study, we investigate the role of KLF8 in oral cancer and the effects of KLF8 knockdown via lentivirus mediated siRNA infection in human adenosquamos carcinoma CAL 27 cells. Study Design: We developed a vector-based siRNA expression system that can induce RNAi in CAL 27 oral cancer cells. Downregulation of KLF8 was confirmed by evaluating GFP expressions, RT-PCR and western blot analysis. Finally, the effects of KLF8 downregulation were analyzed by MTT assay and colony formation assays. Results: The expression levels of KLF8 mRNA and proteins are reduced in CAL 27 cells that transfected with 21- nt siRNA against KLF8. Lentivirus-mediated silencing of KLF8 reduces cell proliferation and colonies number, thereby indicating the role of KLF8 in cell proliferation and tumorigenesis. Conclusions: These results strongly suggest that KLF8 is essential for growth of CAL 27 cancer cells. A better understanding of KLF8 function and processing may provide novel insights into the clinical therapy of oral cancer

Analyzing Gene Expression Profile in K562 Cells Exposed to Sodium Valproate Using Microarray Combined with the Connectivity Map Database

To explore the mechanism underlying antileukaemia effect of sodium valproate, the growth and survival of the K562 cell line were investigated. Global profiles of gene expression in K562 cells exposed to sodium valproate were assessed and validated. The differentially expressed genes identified were further used to query the connectivity map database to retrieve a ranked list of compounds that act on the same intracellular targets as sodium valproate. A significant increase in cell apoptosis and a change in gene expression profile were observed in valproate-exposed K562 cells. The significant enrichment analysis of gene ontology terms for the differentially expressed genes showed that these genes were involved in many important biological processes. Eight differentially expressed genes involved in apoptosis were verified by quantitative real-time PCR. The connectivity map analysis showed gene expression profile in K562 cells exposed to sodium valproate was most similar to that of HDACi and PI3K inhibitors, suggesting that sodium valproate might exert antileukaemic action by inhibiting HDAC as well as inhibiting PI3K pathway. In conclusion, our data might provide clues to elucidate the molecular and therapeutic potential of VPA in leukaemia treatment, and the connectivity map is a useful tool for exploring the molecular mechanism of drug action

Phylogeography of the Sino-Himalayan Fern Lepisorus clathratus on “The Roof of the World”

The Qinghai-Tibetan Plateau (QTP) and its southern and southeastern mountain ranges, Himalaya-Hengduan Mountains (HHM), are one of the most extensive habitats for alpine plants in the world. How ferns occurring in QTP and HHM changed their distribution ranges in response to Quaternary climatic oscillations remains almost unknown.We employed sequences of two chloroplast DNA regions, rps4-trnS and trnL-trnF, to reconstruct phylogeography of the Sino-Himalayan fern Lepisorus clathratus, occurring mainly in the QTP and HHM. Individuals of this species have either dehiscent or indehiscent sporangia with the latter evolved from the plesiomorphic dehiscent forms. Based on a range-wide sampling, we detected 27 cpDNA haplotypes that were divided into five groups by network analyses. Populations in the Hengduan Mountains possess the highest genetic diversity, while a single haplogroup is detected across the north-central region. A distinct phylogeographical subdivision was detected between the Hengduan Mountains and north-central region by AMOVA analysis. The haplogroup distribution pattern, coalescence and AMOVA analysis suggest that a long term survival area (refugia) of the species was located in the Hengduan Mountains during glaciations, with probable range expansions into north-central regions during interglacial periods. Populations with indehiscent sporangium can carry private haplotypes and are inclined to maintain genetic homogeneity. One group with indehiscent sporangia most likely survived in situ on the QTP during glaciations.This study for the first time sheds light on the response of alpine ferns in the QTP and HHM to the Quaternary climatic oscillations