Rodents mediate the relationship between seed rain, seed bank, and plant community with increased grazing disturbance.

Seed rain and the soil seed bank represent the dispersal of seeds in space and time, respectively, and can be important sources of recruitment of new individuals during plant community regeneration. However, the temporal dynamics of seed rain and the mechanisms by which the seed rain and soil seed bank may play a role in plant community regeneration with increased grazing disturbance remain unclear. Seed rain, soil seed bank, aboveground vegetation, and rodent density were sampled along a grazing gradient in an alpine marsh on the eastern Tibetan Plateau. We described the temporal dynamics of seed dispersal using Bayesian generalized mixed models, and nonmetric multidimensional scaling and the structural equation model were used to examine the effects of grazing disturbance on the relative role of seed rain and soil seed bank on aboveground plant community regeneration. The temporal dynamics of seed rain changed from a unimodal to a bimodal pattern with increased grazing disturbance. Both species diversity and seed density of the seed rain and seed bank increased significantly with increased grazing disturbance. Increased grazing disturbance indirectly increased the similarity of composition between seed rain, seed bank, and aboveground plant community by directly increasing species diversity and abundance of aboveground plant community. However, increased grazing disturbance also indirectly decreased the similarity of seed rain, soil seed bank, and aboveground plant community by directly increasing rodent density. The similarity between seed rain and aboveground plant community was greater than that of the soil seed bank and aboveground plant community with increased grazing disturbance. Grazing disturbance spreads the risk of seed germination and seedling establishment by changing the temporal dynamics of seed dispersal. Plants (positive) and rodents (negative) mediated the role of seed rain and soil seed bank in plant community regeneration. The role of seed rain in plant community regeneration is higher than the seed bank in disturbed alpine marshes. Our findings increase our understanding of the regeneration process of the plant community, and they provide valuable information for the conservation and restoration of alpine marsh ecosystems.

Warming reduced flowering synchrony and extended community flowering season in an alpine meadow on the Tibetan Plateau.

The timing of phenological events is highly sensitive to climate change, and may influence ecosystem structure and function. Although changes in flowering phenology among species under climate change have been reported widely, how species-specific shifts will affect phenological synchrony and community-level phenology patterns remains unclear. We conducted a manipulative experiment of warming and precipitation addition and reduction to explore how climate change affected flowering phenology at the species and community levels in an alpine meadow on the eastern Tibetan Plateau. We found that warming advanced the first and last flowering times differently and with no consistent shifts in flowering duration among species, resulting in the entire flowering period of species emerging earlier in the growing season. Early-flowering species were more sensitive to warming than mid- and late-flowering species, thereby reducing flowering synchrony among species and extending the community-level flowering season. However, precipitation and its interactions with warming had no significant effects on flowering phenology. Our results suggest that temperature regulates flowering phenology from the species to community levels in this alpine meadow community, yet how species shifted their flowering timing and duration in response to warming varied. This species-level divergence may reshape flowering phenology in this alpine plant community. Decreasing flowering synchrony among species and the extension of community-level flowering seasons under warming may alter future trophic interactions, with cascading consequences to community and ecosystem function.

Bioinformatic prediction of the structure and characteristics of human sperm acrosome membrane-associated protein 1 (hSAMP32) and evaluation of its antifertility function in vivo.

Human sperm acrosome membrane-associated protein 1 (hSAMP32) plays an important role in the acrosome reaction, sperm-egg primary binding, secondary binding and fusion processes. However, its spatial structural and invivo antifertility function remain unknown. In this study, we first analysed the physical and chemical characteristics and antigenic epitopes of immunised mice using bioinformatics. Then, we constructed the prokaryotic expression vector pcDNA3.1-hSAMP32 to immunise BALB/c mice invivo. IgG antibodies in the serum were detected, and the litter size of female mice and the number of the hamster eggs penetrated were counted. hSAMP32 was found to contain six hydrophilic regions and a signal peptide beginning at amino acid position 29. The transmembrane region of hSAMP32 was located within amino acids 217-239 with α-helices and random coil structures. We predicted five antigenic epitopes. The molecular weight of hSAMP32 was 59 kDa. Moreover, the results of invivo studies revealed that 56 days after the first immunisation, the litter size was significantly smaller for female pcDNA-3.1(+)-hSAMP32-immunised (mean±s.d. 4.33±1.21) than control mice (9.50±0.55), indicating that the immunocontraception vaccine had an antifertility effect. This experiment presents a theoretical and experimental basis for in-depth study of the hSAMP32 mechanism within the sperm-egg fusing process and for the screening of antigenic epitopes with immunocontraceptive properties.