Genetic Diversity and Structure of Apomictic and Sexually Reproducing Lindera Species (Lauraceae) in Japan

Research Highlights: genetic diversity in populations were compared among related shrub species with different reproductive systems. Background and Objectives: Lindera species are dioecious trees or shrubs that produce seeds by mating of males and females. To evaluate the importance of genetic diversity for the persistence of natural populations, we compared genetic information among four Lindera species in Japan. Three are dioecious shrubs (Lindera praecox, Lindera umbellata, and Lindera obtusiloba) that produce seeds by sexual reproduction. The remaining species, Lindera glauca, reproduces by apomixis; only female plants are found in Japan. Materials and Methods: all four species were sampled across a wide geographic area, from Tohoku to Kyushu, Japan. Single nucleotide polymorphisms (SNPs) were detected by multiplexed ISSR genotyping by sequencing (MIG-seq) and the resulting genetic diversity parameters were compared among populations. Results: in all sexually reproducing species, the values of observed heterozygosity were close to the expected ones and the inbreeding coefficients were nearly 0. These results were supposed to be caused by their obligate outcrossing. The genetic difference increased, in ascending order, between a mother plant and its seeds, within populations, and across geographic space. We observed a substantial geographic component in the genetic structure of these species. For L. glauca, the genetic difference between a mother and its seeds, within populations, and across space were not significantly different from what would be expected from PCR errors. Genetic diversity within and among populations of L. glauca was extremely low. Conclusions: apomixis has the advantage of being able to found populations from a single individual, without mating, which may outweigh the disadvantages associated with the extremely low genetic diversity of L. glauca. This may explain why this species is so widely distributed in Japan. Provided that the current genotypes remain suited to environmental conditions, L. glauca may not be constrained by its limited genetic diversity

Exposure of the Yeast <i>Saccharomyces cerevisiae</i> to Functionalized Polystyrene Latex Nanoparticles: Influence of Surface Charge on Toxicity

Novel nanoparticles with unique physicochemical characteristics are being developed with increasing frequency, leading to higher probability of nanoparticle release and environmental accumulation. Therefore, it is important to assess the potential environmental and biological adverse effects of nanoparticles. In this study, we investigated the toxicity and behavior of surface-functionalized nanoparticles toward yeast (<i>Saccharomyces cerevisiae</i>). The colony count method and confocal microscopy were used to examine the cytotoxicity of manufactured polystyrene latex (PSL) nanoparticles with various functional groups (amine, carboxyl, sulfate, and nonmodified). <i>S. cerevisiae</i> were exposed to PSL nanoparticles (40 mg/L) dispersed in 5–154 mM NaCl solutions for 1 h. Negatively charged nanoparticles had little or no toxic effect. Interestingly, nanoparticles with positively charged amine groups (p-Amine) were not toxic in 154 mM NaCl, but highly toxic in 5 mM NaCl. Confocal microscopy indicated that in 154 mM NaCl, the p-Amine nanoparticles were internalized by endocytosis, whereas in 5 mM NaCl they covered the dead cell surfaces. This demonstrates that nanoparticle-induced cell death might to be related to their adhesion to cells rather than their internalization. Together, these findings identify important factors in determining nanoparticle toxicity that might affect their impact on the environment and human health

Exposure of the Yeast <i>Saccharomyces cerevisiae</i> to Functionalized Polystyrene Latex Nanoparticles: Influence of Surface Charge on Toxicity

Novel nanoparticles with unique physicochemical characteristics are being developed with increasing frequency, leading to higher probability of nanoparticle release and environmental accumulation. Therefore, it is important to assess the potential environmental and biological adverse effects of nanoparticles. In this study, we investigated the toxicity and behavior of surface-functionalized nanoparticles toward yeast (<i>Saccharomyces cerevisiae</i>). The colony count method and confocal microscopy were used to examine the cytotoxicity of manufactured polystyrene latex (PSL) nanoparticles with various functional groups (amine, carboxyl, sulfate, and nonmodified). <i>S. cerevisiae</i> were exposed to PSL nanoparticles (40 mg/L) dispersed in 5–154 mM NaCl solutions for 1 h. Negatively charged nanoparticles had little or no toxic effect. Interestingly, nanoparticles with positively charged amine groups (p-Amine) were not toxic in 154 mM NaCl, but highly toxic in 5 mM NaCl. Confocal microscopy indicated that in 154 mM NaCl, the p-Amine nanoparticles were internalized by endocytosis, whereas in 5 mM NaCl they covered the dead cell surfaces. This demonstrates that nanoparticle-induced cell death might to be related to their adhesion to cells rather than their internalization. Together, these findings identify important factors in determining nanoparticle toxicity that might affect their impact on the environment and human health

Exposure of the Yeast <i>Saccharomyces cerevisiae</i> to Functionalized Polystyrene Latex Nanoparticles: Influence of Surface Charge on Toxicity

Novel nanoparticles with unique physicochemical characteristics are being developed with increasing frequency, leading to higher probability of nanoparticle release and environmental accumulation. Therefore, it is important to assess the potential environmental and biological adverse effects of nanoparticles. In this study, we investigated the toxicity and behavior of surface-functionalized nanoparticles toward yeast (<i>Saccharomyces cerevisiae</i>). The colony count method and confocal microscopy were used to examine the cytotoxicity of manufactured polystyrene latex (PSL) nanoparticles with various functional groups (amine, carboxyl, sulfate, and nonmodified). <i>S. cerevisiae</i> were exposed to PSL nanoparticles (40 mg/L) dispersed in 5–154 mM NaCl solutions for 1 h. Negatively charged nanoparticles had little or no toxic effect. Interestingly, nanoparticles with positively charged amine groups (p-Amine) were not toxic in 154 mM NaCl, but highly toxic in 5 mM NaCl. Confocal microscopy indicated that in 154 mM NaCl, the p-Amine nanoparticles were internalized by endocytosis, whereas in 5 mM NaCl they covered the dead cell surfaces. This demonstrates that nanoparticle-induced cell death might to be related to their adhesion to cells rather than their internalization. Together, these findings identify important factors in determining nanoparticle toxicity that might affect their impact on the environment and human health

Exposure of the Yeast <i>Saccharomyces cerevisiae</i> to Functionalized Polystyrene Latex Nanoparticles: Influence of Surface Charge on Toxicity

Novel nanoparticles with unique physicochemical characteristics are being developed with increasing frequency, leading to higher probability of nanoparticle release and environmental accumulation. Therefore, it is important to assess the potential environmental and biological adverse effects of nanoparticles. In this study, we investigated the toxicity and behavior of surface-functionalized nanoparticles toward yeast (<i>Saccharomyces cerevisiae</i>). The colony count method and confocal microscopy were used to examine the cytotoxicity of manufactured polystyrene latex (PSL) nanoparticles with various functional groups (amine, carboxyl, sulfate, and nonmodified). <i>S. cerevisiae</i> were exposed to PSL nanoparticles (40 mg/L) dispersed in 5–154 mM NaCl solutions for 1 h. Negatively charged nanoparticles had little or no toxic effect. Interestingly, nanoparticles with positively charged amine groups (p-Amine) were not toxic in 154 mM NaCl, but highly toxic in 5 mM NaCl. Confocal microscopy indicated that in 154 mM NaCl, the p-Amine nanoparticles were internalized by endocytosis, whereas in 5 mM NaCl they covered the dead cell surfaces. This demonstrates that nanoparticle-induced cell death might to be related to their adhesion to cells rather than their internalization. Together, these findings identify important factors in determining nanoparticle toxicity that might affect their impact on the environment and human health