Environmental DNA (eDNA) technology has been successfully applied to detect organisms in various aquatic ecosystems. However, eDNA has been proven to exist for a long time in environmental samples. The timeliness of eDNA detection results largely depends on the rate of molecular degradation. Environmental RNA (eRNA) is considered an excellent complementary tool because most researchers believe that RNA degrades faster than DNA in vitro, while, to the best of our knowledge, the number of published articles related to eRNA is very limited. To address an important knowledge gap, this study focused on the response mechanism of eRNA degradation to water temperature change as compared with eDNA. Changes in the concentration of eDNA and eRNA of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene from Fenneropenaeuschinensis were detected at four temperatures (10, 15, 20 and 25 °C). The results showed that the degradation rate of eDNA increased with an increase in temperature. The degradation rate constants ranged from 0.011 to 0.486 h⁻¹ and the degradation time ranged from 8 to 383 h for eDNA. The degradation rate of eRNA changed slightly with an increase in temperature. The degradation rate constants ranged from 0.190 to 0.379 h⁻¹ and the degradation time ranged from 11 to 22 h for eRNA. eRNA showed better stability under temperature change and maintained a faster degradation rate at low temperatures. These results provide answers to the questions of whether eRNA and eDNA degradation rates are fast or slow. Furthermore, this study may suggest the potential superiority of eRNA over eDNA and promote further study of eRNA in future research.

Ubiquitination is a major post-translational modification involved in nearly all aspects of eukaryotic biology. Previous RNA-Seq studies showed that ubiquitination plays essential roles in the heat tolerance of Saccharina japonica, but to date, large-scale profiling of the ubiquitome in S. japonica has not been reported. To better understand the regulatory roles of ubiquitination in heat responses of S. japonica, we investigated its ubiquitome under normal and heat stress by the combination of affinity enrichment and high-resolution liquid chromatography-tandem mass spectroscopy analysis. Altogether, 3305 lysine ubiquitination sites in 1562 protein groups were identified. After normalization, 152 lysine ubiquitination sites in 106 proteins were significantly upregulated and 208 lysine ubiquitination sites in 131 proteins were significantly downregulated in response to heat stress. Protein annotation and functional analysis suggested that ubiquitination modulates a variety of essential cellular and physiological processes, including but not limited to the ubiquitin-26S proteasome system, ribosome, carbohydrate metabolism, and oxidative phosphorylation. Our results provide a global view of the heat response ubiquitome in S. japonica, and could facilitate future studies on the physiological roles of these ubiquitination-related proteins.

Fenneropenaeus chinensis is an important economic species in the north of China, and plays an important role in both marine fishing and aquaculture. Long-term overfishing has led to the rapid decline of wild F. chinensis resources. The traditional trawl survey could not meet the demands of the F. chinensis resource survey. In this study, environmental DNA (eDNA) technology was used to evaluate the biomass of F. chinensis in the traditional Qinghai (Qingdao Haiyang) fishing ground in the southern sea area of the Shandong Peninsula, with the purpose of verifying whether eDNA technology can provide a new resource assessment method for fisheries resource species such as F. chinensis. The eDNA quantitative results of the Qingdao water samples ranged from 1972 copies/L to 6937 copies/L, with an average of 4366 ±1691 copies/L. Those in Haiyang water samples ranged from 4795 copies/L to 8715 copies/L, with an average of 6737 ± 1348 copies/L. The concentration of eDNA in shrimp culture ponds ranged from 1.14 × 10⁶ copies/L to 7.61 × 10⁶ copies/L, with an average of 3.33 × 10⁶ ± 2.28 × 10⁶ copies/L. The amount of eDNA released by each gram of F. chinensis per 24 h was about 2.91 × 10⁶ copies. According to this calculation, it was estimated that the distribution of F. chinensis was about one shrimp in every 300 m² sea area. Similarly, it is estimated that one shrimp is distributed every 240 m² in the Haiyang sea area. The result of this study confirms the feasibility of using eDNA to evaluate the biomass of shrimps.