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ABSTRACT The acoustic characteristics of an Amazonian lowland rain forest study site in southern Venezuela was analysed to determine environmental constraints upon acoustic communication. Signal degradation was measured by conducting transmission experiments at different heights above ground level. Measurements of ambient noise served to determine possible communication distances for various times of day, heights above ground level and frequencies. “Sound windows” for acoustic long-range communication were found for low frequencies, calling heights in the midstorey and calling in the morning or during the night. Sound attenuation was affected by height and frequency but not by time of day. Background noise varied remarkably with time of day and frequency and had a greater impact on communication distance than signal attenuation. 相似文献
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Jack C. Slootweg Timo B. van Schaik H. C. Quarles van Ufford Eefjan Breukink Rob M.J. Liskamp Dirk T.S. Rijkers 《Bioorganic & medicinal chemistry letters》2013,23(13):3749-3752
The lipophilic amino acid, (S)-2-aminoundecanoic acid, was synthesized and incorporated at a number of specific positions within the peptide sequence of anoplin. These lipophilic anoplin analogs showed to be more active against Escherichia coli and Staphylococcus aureus compared to native anoplin, while the EC50-value of hemolysis was at least one order of magnitude lower than the MIC values. This was in sharp contrast to the N-acylated anoplin derivative, where a gain in activity also led to a complete loss of selectivity. Thus, the incorporation of a lipophilic amino acid residue into anoplin enhanced the antimicrobial activity, while selectivity towards microbial membranes was retained. 相似文献
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Y Deng J Zhao D Sakurai KM Kaufman JC Edberg RP Kimberly DL Kamen GS Gilkeson CO Jacob RH Scofield CD Langefeld JA Kelly ME Alarcón-Riquelme BIOLUPUS GENLES Networks JB Harley TJ Vyse BI Freedman PM Gaffney KM Sivils JA James TB Niewold RM Cantor W Chen BH Hahn EE Brown PROFILE BP Tsao 《Arthritis research & therapy》2012,14(Z3):A5
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John M. Quarles Nell G. Morris A. Leibovitz 《In vitro cellular & developmental biology. Plant》1982,18(2):165-172
Summary An ex vivo culture system was developed for assessing the activity of cancer chemotherapeutic agents against tumor cells.
The system utilizes artificial capillary culture units and the technique of hemodialysis to expose tumor cells to a chemotherapeutic
drug and its metabolites following injection of the drug into an experimental animal. This ex vivo culture system was used
to test the activity of 5-fluorouracil (5-FU) against four human colorectal adenocarcinoma cell lines (SW 403, SW 480, SW
620, and SW 707). Cell killing by 5-FU or its metabolites in blood dialysate following intravenous injection was measured
by determining colony formation of cells attached to plastic and suspended in 0.3% agar after short-term exposures of 1 to
2 h. The technique was shown to discriminate between the sensitivities of these cell lines and the respective sensitivities
to the drug were reproducible. Kinetics of drug clearance from the host animal’s blood were shown to be similar to that in
humans. The results suggest the system may be useful for testing diverse drugs, including those requiring metabolic activation,
against a variety of types of tumor cells.
Presented in part at the 31st Annual Meeting of the Tissue Culture Association, St. Louis, Missouri, June 1–5, 1980. 相似文献
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EC Dreaden BE Gryder LA Austin BA Tene Defo SC Hayden M Pi LD Quarles AK Oyelere MA El-Sayed 《Bioconjugate chemistry》2012,23(8):1507-1512
Prostate cancer is the most commonly diagnosed cancer among men in the developed countries. (1) One in six males in the U.S. (2) and one in nine males in the U.K. (3) will develop the disease at some point during their lifetime. Despite advances in prostate cancer screening, more than a quarter of a million men die from the disease every year (1) due primarily to treatment-resistance and metastasis. Colloidal nanotechnologies can provide tremendous enhancements to existing targeting/treatment strategies for prostate cancer to which malignant cells are less sensitive. Here, we show that antiandrogen gold nanoparticles-multivalent analogues of antiandrogens currently used in clinical therapy for prostate cancer-selectively engage two distinct receptors, androgen receptor (AR), a target for the treatment of prostate cancer, as well as a novel G-protein coupled receptor, GPRC6A, that is also upregulated in prostate cancer. These nanoparticles selectively accumulated in hormone-insensitive and chemotherapy-resistant prostate cancer cells, bound androgen receptor with multivalent affinity, and exhibited greatly enhanced drug potency versus monovalent antiandrogens currently in clinical use. Further, antiandrogen gold nanoparticles selectively stimulated GPRC6A with multivalent affinity, demonstrating that the delivery of nanoscale antiandrogens can also be facilitated by the transmembrane receptor in order to realize increasingly selective, increasingly potent therapy for treatment-resistant prostate cancers. 相似文献
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Organismic diversity, as well as distributional and ecological patterns, can be fully understood in an evolutionary framework only. Reliable phylogenetic trees are required to ‘read history’, but are not yet available for most marine invertebrate groups. Molecular systematics offers an enormous potential, but still fails for ‘all‐species approaches’ on groups with species that are rare or occur in remote areas only, simply because there is no easily collectable material available for sequence analyses. Exploring morphologically aberrant corambid nudibranch gastropods as a case study, we assess whether or not morphology‐based phylogenetic analyses can fill this gap and produce a tree that allows a detailed view on evolutionary history. Morphology‐based parsimony analysis of corambids and potential relatives resulted in a well‐resolved and remarkably robust topology. As an offshoot of kelp‐associated onchidoridid ancestors, and obviously driven by the heterochronic shortening of life cycles and morphological juvenilization in an ephemeral habitat, the ancestor of corambids originated in cool northern Pacific coastal waters. A basal clade (the genus Loy) diverged there, adapting to live on soft bottoms under successive reversals of paedomorphic traits. The more speciose Corambe lineage radiated preying upon short‐lived encrusting bryozoa in a high‐energy kelp environment. Selection favoured transformation of the mantle into a cuticle‐covered shield, and successive paedomorphic translocations of dorid anal gills to the protected ventral side of the body, where compensatory, multiple gills evolved. Corambe species probably first colonized tropical American seas, and then radiated in worldwide temperate waters: this is explained by the excellent long‐distance dispersal abilities afforded by rafting on kelp, with the subsequent divergence of colonizers in allopatry. The competitive coexistence of Corambe pacifica MacFarland & O'Donoghue, 1929 and Corambe steinbergae (Lance, 1962) off California is the result of independent colonization events. The closing of the Isthmus of Panama separated the latter species from a flock that have radiated within warm Atlantic waters since then. Our case study shows that morphological structures, if investigated in depth, bear the potential for an efficient phylogenetic analysis of groups that are still elusive to molecular analyses. Tracing character evolution and integrating a wide range of geographic, biological, and ecological background information allowed us to reconstruct an evolutionary scenario for corambids that is detailed and plausible, and can be tested by future molecular approaches. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 585–604. 相似文献
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