An efficient in vitro organogenesis protocol for the endangered relic tree species Bretschneidera sinensis and genetic fidelity assessment using DNA markers.

Bretschneidera sinensis is a monotypic species of rare and tertiary relic trees mainly distributed in China. B. sinensis is a potentially valuable horticultural plant, which has significant ornamental and research value, and is a crucial tool for the study of phylogeography. The artificial cultivation of B. sinensis is of great scientific value and practical significance. In this study, we developed a direct organogenesis process of B. sinensis using mature zygotic embryos as initial materials. The highest sterile germination induction (54.5%) from the mature zygotic embryo was obtained in a Murashige and Skoog (MS) medium with 2.0 mg·L-1 6-benzylaminopurine (6-BA) and 0.2 mg·L-1 α-naphthaleneacetic acid (NAA). The highest percentage of shoot regeneration (90.37%) was attained using 1.0 mg·L-1 6-BA and 0.01 mg·L-1 NAA in the MS medium. The Woody Plant Medium (WPM) had the greatest adventitious shoot elongation rate of 93.33%. The most optimized rooting rate was 88.89% in a half-strength MS medium containing 2.0 mg·L-1 indole-3-butyric acid (IBA) and 1.0 mg·L-1 NAA. The genetic fidelity of in vitro regenerated plantlets was assessed using inter-simple sequence repeats and random amplified polymorphic DNA molecular markers, confirming the genetic uniformity and stability of regenerated B. sinensis plantlets. Our research presents an effective in vitro propagation system for B. sinensis, laying the groundwork for its germplasm conservation and large-scale production while maintaining high genetic integrity.

Electric bicycle cost calculation models and analysis based on the social perspective in China.

Electric bicycles (EBs) are increasingly popular around the world. In April 2014, EB ownership in China reached 181 million. While some aspects of the impact of EBs have been studied, most of the literature analyzing the cost of EBs has been conducted from the buyer's point of view and the perspective of social cost has not been covered, which is therefore the focus of this paper. From the consumer's point of view, only the costs paid from purchase until retirement are included in the cost of EBs, i.e., the EB acquisition cost, battery replacement cost, charging cost, and repair and maintenance cost are included. Considered from the perspective of the social cost (including impact on the environment), costs that are not paid directly by consumers should also be included in the cost of EBs, i.e., the lead-acid battery scrap processing cost, the cost of pollution caused by wastewater, and the traffic-related costs. Data are obtained from secondary sources and surveys, and calculations demonstrate that in the life cycle of an EB, the consumer cost is 6386.2 CNY, the social cost is 10,771.2 CNY, and the ratio of consumer to social cost is 1:1.69. By comparison, the ratio for motor vehicles is 1:1.06, so that the share of the life cycle cost of EBs that is not borne by the consumer is much higher than that for motor vehicles, which needs to be addressed.