The interest in label-free bioassays is increasing rapidly because of their simple procedure and direct information on the interaction between the target molecule and the sensing unit. One of the major obstacles in the application of label-free biosensors is the difficulty to produce stable and reproducible optical, electric, electrochemical, or magnetic properties for the sensitive detection of the target molecules. In this work, we demonstrated a label-free DNA assay, by directly measuring the intrinsic Cu andCu stable isotopes inside the double-strand DNA-templated Cu nanoparticles. The experimental conditions, including detection of copper by elemental mass spectrometry, the copper nanoparticles formation parameters, the hybrid chain reaction parameters, and analytical performance, were investigated in detail. The Cu signal intensity possesses a linear relation with the concentration of target DNA over the range of 20-1000 pM with a detection limit of 4 pM (3σ). The detection limit of this method is among the most sensitive label-free techniques and also comparable to the lanthanides and Au nanoparticles labeled assays by elemental mass spectrometric detection. The proposed label-free bioassay is simple and sensitive and eliminated the need for optical, electric, electrochemical, or magnetic properties of the sensing unit. To our best knowledge, this is the first report of the label-free bioassay by metal stable isotope detection.

Male sterility is an important tool for plant breeding and hybrid seed production. Male-sterile mutants are largely due to an abnormal development of either the sporophytic or gametophytic anther tissues. Tapetum, a key sporophytic tissue, provides nutrients for pollen development, and its delayed degeneration induces pollen abortion. Numerous bHLH proteins have been documented to participate in the degeneration of the tapetum in angiosperms, but relatively little attention has been given to the evolution of the involved developmental pathways across the phylogeny of land plants. A combination of cellular, molecular, biochemical and evolutionary analyses was used to investigate the male fertility control in Medicago truncatula. We characterized the male-sterile mutant empty anther1 (ean1) and identified EAN1 as a tapetum-specific bHLH transcription factor necessary for tapetum degeneration. Our study uncovered an evolutionarily conserved recruitment of bHLH subfamily II and III(a + c)1 in the regulation of tapetum degeneration. EAN1 belongs to the subfamily II and specifically forms heterodimers with the subfamily III(a + c)1 members, which suggests a heterodimerization mechanism conserved in angiosperms. Our work suggested that the pathway of two tapetal-bHLH subfamilies is conserved in all land plants, and likely was established before the divergence of the spore-producing land plants.

Soil enzymes and microbial communities are key factors in forest soil ecosystem functions and are affected by stand age. In this study, we studied soil enzyme activities, composition and diversity of bacterial and fungal communities and relevant physicochemical properties at 0–10 cm depth (D1), 10–20 cm depth (D2) and 20–30 cm depth (D3) soil layers in 3-(3a), 6-(6a), 12-(12a), 18-(18a), 25-(25a), 32-(32a) and 49-year-old (49a) Chinese fir plantations to further reveal the effects of stand age on soil biotic properties. Spectrophotometry and high-throughput sequencing was used to assess the soil enzyme activity and microbial community composition and diversity of Chinese fir plantation of different stand ages, respectively. We found that soil catalase activity increased as the stand age of Chinese fir plantations increased, whereas the activities of urease, sucrase and β-glucosidase in 12a, 18a and 25a were lower than those in 6a, 32a and 49a. Shannon and Chao1 indices of bacterial and fungal communities first decreased gradually from 6a to 18a or 25a and then increased gradually from 25a to 49a. Interestingly, the sucrase and β-glucosidase activities and the Shannon and Chao1 indices in 3a were all lower than 6a. We found that the relative abundance of dominant microbial phyla differed among stand ages and soil depths. The proportion of Acidobacteria first increased and then decreased from low forest age to high forest age, and its relative abundance in 12a, 18a and 25a were higher than 3a, 32a and 49a, but the proportion of Proteobacteria was opposite. The proportion of Ascomycota first decreased and then increased from 6a to 49a, and its relative abundance in 12a, 18a and 25a was lower than 3a, 6a, 32a and 49a. Our results indicate that soil enzyme activities and the richness and diversity of the microbial community are limited in the middle stand age (from 12a to 25a), which is important for developing forest management strategies to mitigate the impacts of degradation of soil biological activities.

Emerging evidence indicates that resistin and fascin-1 may possess a causal role in the development of several types of cancers. However, the clinical significance of resistin expression in colorectal cancer (CRC) tissues is unclear, and there are no reports of any correlation between resistin and fascin-1. Our analyses explored the expression of resistin in CRC tissue and analyzed the clinical and prognostic significance of the observed positive correlation between resistin and fascin-1. The rate of strongly positive resistin expression (27.5%) was significantly higher in CRC tissues than in normal colorectal tissues (5.2%). Strongly positive resistin expression is related to multiple poor prognostic factors in CRC, including depth of tumor invasion, lymph node metastasis, and tumor stage. In this study, survival was worse in CRC patients with high levels of both resistin and fascin-1 expression than in those with high levels of only one protein or normal levels of both proteins. We suggest that a combined high level of resistin and fascin-1 expression correlates reliably with survival in CRC, so it may serve as a potential therapeutic target.