Pollen Streptomyces Produce Antibiotic That Inhibits the Honey Bee Pathogen Paenibacillus larvae

Humans use natural products to treat disease; similarly, some insects use natural products produced by Actinobacteria to combat infectious pathogens. Honey bees, Apis mellifera, are ecologically and economically important for their critical role as plant pollinators and are host to diverse and potentially virulent pathogens that threaten hive health. Here, we provide evidence that Actinobacteria that can suppress pathogenic microbes are associated with A. mellifera. We show through culture-dependent approaches that Actinobacteria in the genus Streptomyces are commonly isolated from foraging bees, and especially common in pollen stores. One strain, isolated from pollen stores, exhibited pronounced inhibitory activity against Paenibacillus larvae, the causative agent of American foulbrood. Bioassay-guided HPLC fractionation, followed by NMR and mass spectrometry, identified the known macrocyclic polyene lactam, piceamycin that was responsible for this activity. Further, we show that in its purified form, piceamycin has potent inhibitory activity toward P. larvae. Our results suggest that honey bees may use pollen-derived Actinobacteria and their associated small molecules to mediate colony health. Given the importance of honey bees to modern agriculture and their heightened susceptibility to disease, the discovery and development of antibiotic compounds from hives could serve as an important strategy in supporting disease management within apiaries.National Institute for Health/[U19 AI142720]/NIH/Estados UnidosNational Institute of Food and Agriculture/[WISO1321]/NIFA/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Estructuras Microscópicas (CIEMIC)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM

Microtermolides A and B from Termite-Associated Streptomyces sp. and Structural Revision of Vinylamycin

Microtermolides A (1) and B (2) were isolated from a Streptomyces sp. strain associated with fungus-growing termites. The structures of 1 and 2 were determined by 1D- and 2D-NMR spectroscopy and high-resolution mass spectrometry. Structural elucidation of 1 led to the re-examination of the structure originally proposed for vinylamycin (3). Based on a comparison of predicted and experimental $^1$H and $^{13}$C NMR chemical shifts, we propose that vinylamycin’s structure be revised from 3 to 4

Differential susceptibility to etoposide in clones derived from a human ovarian cancer cell line

Objectives: To identify parameters/factors that may contribute to the differential sensitivity to etoposide in two clones isolated from the human ovarian carcinoma SKOV-3 cell line, which does not express p53 and is resistant to platinum-based regimens. Methods: Differential sensitivity of the cells to etoposide was monitored by microscopy to observe morphological changes, by flow cytometry analyses to detect cell cycle perturbations, and by molecular/biochemical assays to identify events involved in induction of apoptosis. Results: Etoposide treatment (1) induced apoptosis in one clone, ES, but not in another clone, ER, (2) had no effect on the expression of the antiapoptotic proteins Bcl-2 and Bcl-X L in both cell clones, whereas the proapoptotic proteins Bak and Bax were dramatically upregulated in ES, but not ER cells, and (3) induced more extensive processing of procaspase-8, procaspase-9, and the caspase-3-targeted substrates, topoisomerase I and PARP, in ES cells. Ectopic overexpression of Bcl-2 in ES cells failed to inhibit etoposide-induced apoptosis. Conclusions: The differential susceptibility of ES and ER cells to etoposide-induced apoptosis is associated with differences in several events rather than with a specific single genetic regulator of the apoptotic machinery. We propose that the differential response of ovarian cancer patients to etoposide treatment is associated with the number of etoposide-sensitive cells in the tumor. Copyright © 2006 S. Karger AG

Sclareol induces apoptosis in human HCT116 colon cancer cells in vitro and suppression of HCT116 tumor growth in immunodeficient mice

Labd-14-ene-8, 13-diol (sclareol) is a labdane-type diterpene, which has demonstrated significant cytotoxic activity against human leukemic cell lines, but its effect on solid tumor-derived cells is uknown. Here, we demonstrate that addition of sclareol to cultures of human colon cancer HCT116 cells results in inhibition of DNA synthesis, arrest of cells at the G1 phase of the cell cycle, activation of caspases-8, -9, PARP degradation, and DNA fragmentation, events characteristic of induction of apoptosis. Intraperitoneal (ip) administration of sclareol alone, at the maximum tolerated dose, was unable to induce suppression of growth of HCT116 tumors established as xenografts in immunodeficient SCID mice. In contrast, ip administration of liposome-encapsulated sclareol, following a specific schedule, induced suppression of tumor growth by arresting tumor cell proliferation as assessed by detecting the presence of the cell proliferation-associated nuclear protein, Ki67, in thin tumor sections. These findings suggest that sclareol incorporated into liposomes may possess chemotherapeutic potential for the treatment of colorectal and other types of human cancer. © 2007 Springer Science+Business Media, LLC