Fractional grey unequal-interval time-varying Lotka-Volterra model and its application for microbial communities in compost.

Aerobic compost is an effective method for the treatment of livestock manure, which is usually accompanied by complex interspecific competition. Describing these competitive relationships through mathematical models can help understand the interaction of microorganisms and analyze the effect of exogenous additive to regulate the composting process. The common model for analyzing competition problem is the Lotka-Volterra model. However, the fixed parameters of the Lotka-Volterra model are not suitable to reflect the dynamic variations of the competitive relationship when the environmental conditions change during composting process. Therefore, this paper establishes a novel fractional grey unequal-interval time-varying Lotka-Volterra model. Firstly, a fractional grey derivate operator is proposed on the basis of the unequal interval of composting data and historical dependence of microbial growth. Secondly, considering the influence of temperature, a time-varying parameter matrix is defined to reflect the variation of competitive relationship at different composting phases, and it is estimated by forgetting factor recursive least squares. Thirdly, the optimal coefficients are optimized by grey prediction evolution algorithm. Finally, the proposed model is employed to analyze the chicken manure composting experiment. The results show that the proposed model has lower error criteria and more accurate trend of fitting curve than the other five existing models. The parameter matrix describes the dynamical variation of microbial competitive relationship in two taxonomic levels and reveals that effect of the exogenous additive is principally reacted in the thermophilic phase and the competitive advantage is shifted from Bacteroidota to Firmicutes after treatment with the exogenous additive.

An improved method used for evaluating potential environmental pollution risk based on spatial distribution and density of farms.

The livestock manure nitrogen load on farmland (LMNLF) is often used to assess the potential environmental pollution risk of livestock manure nitrogen nutrient (LMN) in a target region. First, the LMNLF of Wuhan city is calculated, and the potential environmental pollution risk of LMN is mainly concentrated in Jiangxia District, Xinzhou District, and Huangpi District, but does not exceed the European Union (EU) standards. Heat map results also certificate this conclusion. Therefore, these three districts are the research emphases. Second, considering spatial distribution of farms, an improved LMNLF method is proposed combining the previous LMNLF and density-based spatial clustering of applications with noise (DBSCAN) methods. Several regions with pollution risks including seven regions in Jiangxia District, one in Xinzhou District, and one in Huangpi District are found out using the improved LMNLF method. Third, to evaluate the carrying capacity of the intensive breeding areas more reasonably, 2 km is taken as the farthest transportation distance of manure; there is still one region in Huangpi District which has serious pollution risk on the environment. These above results can help evaluate the pollution degree of livestock manure to the surrounding environment more precisely.

The transcriptomes from two adipocyte progenitor cell types provide insight into the differential functions of MSTN.

Myostatin (MSTN) was previously shown to differentially regulate the adipogenesis of adipose-derived stem cells (ADSCs) and muscle satellite cells (MSCs), both of which can serve as progenitor cells for intramuscular adipocytes. We previously showed that MSTN mediates the differential regulation of MyoD and PPARγ in ADSCs and MSCs. Here, we analyzed the effects of MSTN on whole-transcriptome expression profiles of ADSCs and MSCs, revealing that MSTN differentially regulates ADSCs and MSCs, with MSCs being more responsive to MSTN treatment. More genes and pathways were altered in MSCs than in ADSCs. These changes may be responsible for the differences in the adipogenesis potential of ADSCs and MSCs after MSTN treatment. Analysis of the functions of genes that are differentially expressed in ADSCs and MSCs showed that KLF6 is a positive regulator of adipogenesis. In conclusion, the results provide important molecular insights into the regulatory mechanisms of MSTN in ADSCs and MSCs.

Developmental changes of Insulin-like growth factors in the liver and muscle of chick embryos.

The insulin-like growth factors ( IGFS: ) are synthesized in tissues and play an important role in embryonic development of avian via autocrine/paracrine mechanisms. In the study, mRNA expression of IGFs were detected by real-time PCR in the muscle and liver from d 10 to 20 of chick embryo ( E10: to E20: ). Methylation of IGF1 promoter in the muscle was analyzed by bisulfite sequencing PCR as well as IGF2 promoter in the liver. These results showed that there was obviously IGF1 expression in liver at E19 and E20. The higher IGF1 expression in muscle was found during E15 to E18 with the peak on E17, and then declined. Correspondingly, the lowest methylation level of IGF1 promoter was detectable on the same embryonic d 17. Expression of IGF2 in muscle increased gradually during embryonic growth and showed higher level in the later stages (E17 to E20) when IGF1 expression began to decrease. IGF2 expression in liver reached the first peak on E14, then declined but gradually elevated from E17. IGF2 promoter methylation in liver showed gradual decline on d 12, 15, 17 and 19 of incubation, meanwhile IGF2 expression of liver increased gradually. These results suggested that IGF1 and IGF2 might separately be more important for muscle and liver growth in chick embryonic development. Variation of IGFs expression during the incubation might be concerned with the methylation of gene promoter. The profile of IGFs expression in chick embryonic tissues may be meaningful for understanding organ growth and embryonic development in chick.