Microplastics pollution and seawater temperature rise have been the major environmental issues, threatening the survival and biodiversity of marine organisms. This study evaluated the combined eff ect of temperature and polystyrene microplastics (MP) on Artemia , a fi lter-feeding crustacean that is widely used for environmental toxicology studies. Brine shrimp Artemia franciscana were exposed to three MP concentrations (0, 0.2, and 2.0 mg/L) and three temperatures (22, 26, and 30 °C) for 14 d. In general, higher MP concentration and temperature led to a decreased survival rate and growth. Two-way ANOVA analysis indicated that the survival rate of Artemia was signifi cantly impacted by both MP concentration and temperature ( P <0.05), but there was no signifi cant interaction between two factors ( P >0.05). Growth of Artemia was signifi cantly impacted by temperature ( P <0.05), and with a signifi cant interaction between two factors ( P <0.05). Furthermore, the enzymatic activity, intestinal histological analyses, and immune gene expression were determined for Artemia reared at 30 °C with three MP concentrations (0, 0.2, and 2.0 mg/L). The results showed that 2.0-mg/L MP resulted in reduced Artemia intestinal microvilli and exfoliated epithelia cells, signifi cantly increased acid phosphatase (ACP) activity ( P <0.05) and immunerelated gene ADRA1B and CREB3 expression, revealing that higher MP concentration could induce oxidative and immunological stress on Artemia at 30 °C. Overall, our study suggests that MP and temperature have combined adverse eff ect on Artemia , especially at relatively high temperature and polystyrene MP concentration. These fi ndings are important to understand the potential ecological risks posed by these two factors on the organisms in marine environment.

Halophilic zooplankton brine shrimp Artemia has been used as an experimental animal in multidisciplinary research. However, the reproductive patterns and regulation mechanisms of Artemia remain a mystery. In this study, the ovarian development process of parthenogenetic Artemia (P. Artemia) was distinguished into five stages, and oogenesis or egg formation process was identified with six phases. The mode of oogenesis was assumed polytrophic. Moreover, we traced the dynamic translocation of germline stem cells (GSCs), elucidated several key cytological events in oogenesis. Notably, distinguished from the ovary structure of insects and crustaceans, P. Artemia germarium originated from ovariole buds and located in the base of the ovarioles. RNA-seq revealed that 2657 up-regulated genes related to reproduction were obtained. Furthermore, Gbb, Dpp, piwi, vasa, nanos, VgA and VgR were screened and also verified by qPCR. Silencing of the VgR gene in P. Artemia (PA-VgR) at stage Ⅱ of ovarian development led to a low level of gene expression (＜10%) within five days, which resulted variations of oogenesis-related gene expression and significantly inhibited vitellogenesis, impeded oocyte maturation, and eventually decreased the offspring number. In conclusion, we illustrated the patterns of ovarian development, outlined the key spatio-temporal features of oogenesis and established a platform for gene function research using P. Artemia as an experimental animal. These results lay the foundation for studying the reproductive biology of invertebrates, may also provide a novel insight in the reproductive regulation mechanism of aquatic animals in extreme environments.

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Archaeal carotenoids, as novel bioactive compound, are stronger free radical scavenger. The effects of archaea Halorubrum carotenoids on skin coloration, antioxidative status and immune-related genes expression of golden trout Oncorhynchus mykiss were investigated. In total, 420 fish (10.90 ± 0.06 g) were divided into three groups with four replicates, and fed with commercial diets containing 0 (Ctrl), 25 mg/kg (P25)