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Parakmeria omeiensis an evergreen tree belonged to Parakmeria of Magnoliaceae, is listed as a critically endangered plant under the first-grade State protection. Aimed to clarify the abortion period of male sterility in bisexual flowers of P. omeiensis and its physiological and biochemical characteristics, sterile stamens of bisexual flower and fertile stamens of male flower were test materials, the anther development was observed by paraffin section, the contents of soluble sugar, soluble protein, proline were determined, and catalase (CAT) and peroxidase (POD) activities were analyzed. The results were as follows: (1) Significant difference were detected in meiosis stage in anther development between sterile stamens and fertile stamens, the tapetum layer of sterile stamens was dense and undeveloped, the microspore mother cells didn’t develop into the tetrad and subsequently disintegrated, so the pollen sac was empty. The tapetum layer and the microspore mother cells of fertile stamens developed normally, most pollen sac were broken and pollen grain were export. (2) The contents of soluble sugar, soluble protein, proline of sterile stamens were significantly lower than fertile stamens during the stages of meiosis, microspore monuclear and pollen mature. (3) POD activity of sterile stamens increased overall and was significantly higher than fertile stamens during the stages of meiosis, microspore monuclear and pollen mature. CAT activity of sterile stamens decreased as a whole and was significantly lower than fertile stamens in the same stage. We conclude that the microspore abortion occurs at the stage of meiosis, the decrease in metabolism of material and energy causes the abortion of male in bisexual flowers, the tapetum layer don’t develop further and it doesn’t provide nutrients to the microspore mother cells. CAT and POD activities are abnormal which results in the failure of timely scavenging free radicals in cells, and meiosis of microspore mother cells is blocked, so tetrads fail to be formed.

Background: The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critically endangered and has suffered from extensive habitat loss and fragmentation. Knowledge of its habitat preference could assist the conservation of the species and associated ecosystem. In the present study, spatiotemporal variations and driving factors of habitat use of a Yangtze finless porpoise population were studied in a 30-km section of the Yangtze mainstream. Seasonal variation in porpoise occurrences was observed based on visual surveys conducted from 2022 to 2023, with five surveys during the dry season and seven surveys during the wet season. Biological and environmental factors were synchronously sampled in both seasons. The maximum entropy model (MaxEnt) was applied to get the effects of biological and environmental variables on porpoise habitat preference. Results: Within the study area, high-suitability habitats of the finless porpoises accounted for 19.0% and 15.4% of the area during the dry and wet seasons, respectively. The high-suitability habitat shifted from the mainstream in the dry season to the sandbar head and tributary area in the wet season. In the dry season, variables influencing the distribution were phytoplankton biomass, water velocity, and zooplankton biomass, which contributed 97.05% variation in the MaxEnt modeling. In the wet season, water depth, surface water temperature, and zooplankton biomass accounted for 97.69% variation of the distribution. Above results highlight that food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. This is because plankton is the primary food source for filter-feeding and omnivorous fish, especially those in the upper-middle layer which are frequently preyed on by finless porpoises. Conclusion: Suitable areas for finless porpoises, particularly those with high suitability, differed significantly across seasons at a fine-scale in the Yangtze mainstream. Seasonal variations in habitat were driven by different factors. But food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. These results suggest prioritizing conservation of the finless porpoise in the dry season when fish resources are relatively scarce. Measures including monitoring and evaluating prey resources should be considered. More attention should also be paid on management of shipping in the dry season given that the high-suitability habitat of the finless porpoises shifts to the mainstream. [ABSTRACT FROM AUTHOR]

The article discusses the study that characterizes the composition of milk protein in Yangtze finless porpoise. Topics include the classification of the Yangtze finless porpoise as critically endangered due to its low population viability and its small population size, the important role of milk on the physiological processes of offspring and the use of a proteomic approach on the characterization of the milk proteins.