Morphological Effects of Natural Products on Schizosaccharomyces pombe Measured by Imaging Flow Cytometry

Gaining a full understanding of the mechanisms of action of natural products as therapeutic agents includes observing the effects of natural products on cellular morphology,because abnormal cellular morphology is an important aspect of cellular transformations that occur as part of disease states.In this study a set of natural products was examined in search of small molecules that influence the cylindrical morphology of fission yeast Schizosaccharomyces pombe.Imaging flow cytometry of large populations of S.pombe exposed to natural products captured cell images and revealed changes in mean length and aspect ratio of cells.Several natural products were found to alter S.pombe’s morphology relative to control,in terms of elongating cells,shrinking them,or making them more round.These results may facilitate future investigations into methods by which cells establish and maintain specific shapes.

Bacillus sp. SAB E-41-derived extract shows antiaging properties via ctt1-mediated oxidative stress tolerance response in yeast Schizosaccharomyces pombe

Objective: To analyze potential activation of oxidative stress tolerance systems by SAB E-41 bacterial extract in promoting the life span of yeast Schizosaccharomyces pombe. Methods: In vitro analysis was done to assess antioxidant activity of SAB E-41 bacterial extract. Antiaging property of the particular extract was then assayed through spot test and chronological life span assays. Furthermore, sty1 mitogen-activated protein kinase, pap1 transcriptional factor of oxidative stress response and its downstream genes, ctt1 were evaluated via real time PCR. The protein level of ctt1 was then observed via Western Blot analysis. In addition, accumulation of reactive oxygen species and mitochondrial activity were conducted to understand the effect of SAB E-41 upon oxidative stress response systems in vivo. Results: The IC50 values of corresponding extract for antioxidant(DPPH; ABTS) and antiglycation were 402.40, 358.13 and 683.55 μg/mL, respectively. In addition, SAB E-41 extract(750 μg/mL) exhibited antiaging properties, which could be attributed to significant up-regulation of oxidative stress response genes, sty1, pap1 and ctt1. Interestingly, SAB E-41 extract could enhance stress tolerance phenotype of Schizosaccharomyces pombe against H2 O2-induced oxidative stress. These results were supported by increasing mitochondrial activity and reactive oxygen species intracellular levels. Conclusions: SAB E-41 extract could promote yeast life span likely via up-regulation of oxidative stress responses in yeast. Our results suggest that adaptive response via up-regulation of oxidative stress transcriptional factors, and its downstream gene, ctt1, as well as mitochondrial activity contributes in combating oxidative stress thus promoting yeast life span.

Effect in Cell Cycle Caused by Overexpression of SpTrz2p in Schizosaccharomyces pombe

[ Objective] This study aimed to investigate the effect in cell cycle caused by overexpression of SpTrz2p in Schizosaccharomyces pombe. [ Method] The trz2 ~ gene from S. pombe was cloned into pREPgx plasmid to construct an overexpression vector of SpTrz2p, which was then transformed into wild-type S. pombe ceils. The cell cycle was determined with flow cytometry. [ Result ] Overexpression of SpTrz2p in yeast caused changes in cell morphology and cell cycle. The majority of the cells were arrested at G1 phase, indicating that overexpression of SpTrz2p indeed affected the cell cycle. [ Conclusion] This study suggested that overexpression of SpTrz2p is lethal to the cells by affecting the cell cycle.

羟胺对粟酒裂殖酵母(Schizosaccharomyces pombe)的诱变效应

羟胺(HA)引起S.pombe的失活作用因菌株而异,实验用两株突变体的失活曲线皆非指数曲线。钠离子对HA所处理的细胞不仅沒有保护作用,反而会引起细胞损伤。HA的两种独立的效应——失活与诱变效应在以S.pombe为材料的实验里沒有观察到。相反,低浓度HA(0.01M)既能引起S.pombe细胞失活,又有诱变作用。 HA对4类19株NA-生化突变体的回复诱变材料证明:有些NA-生化突变体的突变位点之碱基对为GC,另外一些突变体目前则尚难确定,有待进一步确证。HA同样诱发S.pombe野生型菌株产生大量正向突变体。因而它可供作选育生产菌株的诱变剂。

Screening and Purification of Natural Products from Actinomycetes that Induce a“Rounded”Morphological Phenotype in Fission Yeast

This study was designed to identify and investigate bioactive natural product compounds that alter the cellular shape of the fission yeast Schizosaccharomyces pombe and induce a“rounded”or“small”cellular morphological phenotype.Bioassays using a range of antifungal agents against a multidrug-sensitive fission yeast strain,SAK950 showed that many induced a“rounded”phenotype.We then investigated whether 46 of the actinomycete strains identified in our previous study as inducing a similar phenotype produced antifungal agents of similar classes.We show that five of the strains produced streptothricin and that 26 strains produced polyenes,including fungichromin,filipin and candicidin,the last of which was produced by 24 strains.A taxonomic study of the strains indicated that the majority of the candicidin only producers were Streptomyces hydrogenans and S.albidoflavus whilst those that additionally produced streptothricin were related to S.enissocaesilis.A follow-up study to investigate the natural products made by related strains indicated that they followed a similar pattern.The identification of several compounds from the actinomycete strains similar to the antifungal agents initially tested confirm the validity of an approach using the S.pombe morphological phenotype and actinomycete taxonomy as a predictive tool for natural product identification.