Microbial community interactions determine the mineralization of soil organic phosphorus in subtropical forest ecosystems.

In subtropical forest ecosystems with few phosphorus (P) inputs, P availability and forest productivity depend on soil organic P (Po) mineralization. However, the mechanisms by which the microbial community determines the status and fate of soil Po mineralization remain unclear. In the present study, soils were collected from three typical forest types: secondary natural forest (SNF), mixed planting, and monoculture forest of Chinese fir. The P fractions, Po-mineralization ability, and microbial community in the soils of different forest types were characterized. In addition, we defined Po-mineralizing taxa with the potential to interact with the soil microbial community to regulate Po mineralization. We found that a higher labile P content persisted in SNF and was positively associated with the Po-mineralization capacity of the soil microbial community. In vitro cultures of soil suspensions revealed that soil Po mineralization of three forest types was distinguished by differences in the composition of fungal communities. We further identified broad phylogenetic lineages of Po-mineralizing fungi with a high intensity of positive interactions with the soil microbial community, implying that the facilitation of Po-mineralizing taxa is crucial for soil P availability. Our dilution experiments to weaken microbial interactions revealed that in SNF soil, which had the highest interaction intensity of Po-mineralizing taxa with the community, Po-mineralization capacity was irreversibly lost after dilution, highlighting the importance of microbial diversity protection in forest soils. In summary, this study demonstrates that the interactions of Po-mineralizing microorganisms with the soil microbial community are critical for P availability in subtropical forests.IMPORTANCEIn subtropical forest ecosystems with few phosphorus inputs, phosphorus availability and forest productivity depend on soil organic phosphorus mineralization. However, the mechanisms by which the microbial community interactions determine the mineralization of soil organic phosphorus remain unclear. In the present study, soils were collected from three typical forest types: secondary natural forest, mixed planting, and monoculture forest of Chinese fir. We found that a higher soil labile phosphorus content was positively associated with the organic phosphorus mineralization capacity of the soil microbial community. Soil organic phosphorus mineralization of three forest types was distinguished by the differences in the composition of fungal communities. The positive interactions between organic phosphorus-mineralizing fungi and the rest of the soil microbial community facilitated organic phosphorus mineralization. This study highlights the importance of microbial diversity protection in forest soils and reveals the microbial mechanism of phosphorus availability maintenance in subtropical forest ecosystems.

[Effect of Dendrobium officinale superfine powder on stomach Yin deficiency model mice induced by "spicy overeating"].

Dendrobium officinale is a traditional Chinese medicine for nourishing Yin and benefiting stomach. Its superfine powder has many advantages, such as good dissolution, high utilization rate, strong integrity and easy to use. However, the researches on effect of D. officinale superfine powder on stomach Yin deficiency model are still not sufficient. In this experiment, we explored the effect of D. officinale superfine powder in mice model with stomach Yin deficiency caused by "spicy overeating", and provided certain reference value for its application in gastrointestinal diseases. Male ICR mice were randomly divided into normal group, model group, Yiweitang group, omeprazole group, and D. officinale superfine powder high, medium and low dose groups. The mixture of wine and pepper liquid was given by gavage administration for 30 d, and the corresponding drug was given for 60 d while the model was conti-nued. The body weight, food intake, water intake, fecal moisture content and particle number, foot temperature of mice were measured. The levels of serum gastrin(Gas), motilin(MTL) and somatostatin(SS) were measured by ELISA. Gastric histomorpho-logy was observed by HE staining. The expression levels of nuclear factor kappa B(NF-κB) and cyclooxygenase-2(COX-2) were determined by immunohistochemistry. The expression levels of B-cell lymphoma-2(Bcl-2) and Bcl-2 associated X protein(Bax) in gastric tissues were detected by Western blot. The results showed that D. officinale superfine powder could increase the food intake, water intake, fecal moisture content and particle number, reduce the foot temperature, improve the pathological changes of gastric mucosa, reduce the expression of NF-κB, COX-2 protein in gastric tissues, and increase the ratio of Bax/Bcl-2. D. officinale superfine powder can "nourish Yin and benefit the stomach", improve the syndrome of stomach Yin deficiency, such as "hunger but not want to eat, dry mouth but not want to drink, hand and feet hot, constipation", and reduce the damage of gastric mucosa. The mechanism may be related to regulating the secretion of gastrointestinal hormones, inhibiting the inflammation of gastric tissues and promoting the apoptosis of abnormal cells in gastric tissues.

[Effect of Dendrobium officinale on Yin deficiency constipation induced by warm-drying medicine in mice].

Dendrobium officinale is a sacred product for nourishing Yin and has a clear "thick gastrointestinal" effect. Modern pharmacological studies had found that it could improve gastrointestinal function. This study observed the improvement effect of D. officinale on constipation model mice with Yin deficiency caused by warm-drying medicine. It provided experimental basis for the treatment of Yin deficiency constipation. The male and female ICR mice were randomly divided into normal group, model group, D. officinale high, medium and low dose groups(0.6, 0.4, 0.2 g·kg~(-1)), and phenolphthalein tablets group. The model mice of Yin deficiency constipation were established by gavage with warm-drying medicine. The overall state and body temperature of the mice were observed and recorded. The number of feces, feces weight, fecal moisture content and intestinal propulsion were measured. The morphological damage of colon tissue was observed by hematoxylin-eosin(HE) staining. The expression of inducible nitric oxide synthase(iNOS) in the colon was detected by Western blot and immunohistochemical method. The expression of iNOS mRNA in the colon was detected by Real-time fluorescence quantitative PCR, and the serum cyclic guanosine phosphate(cGMP) level was detected the enzyme-linked immunosorbent assay(ELISA). The results showed that D. candidum could reduce the body temperature of mice with Yin deficiency constipation, increase the number of feces, wet feces, dry feces and intestinal propulsion ability, reduce the expression of iNOS protein and mRNA in the colon, and reduce the content of cGMP in the serum. It showed that D. candidum could improve the symptoms of Yin deficiency constipation mice caused by warm-drying medicine, and the mechanism may be related to reducing the expression of iNOS in the colon and increasing intestinal motility.

[Effect of Wubi Shanyao Pills on sexual dysfunction in rats with adenine-induced kidney-Yang deficiency].

The aim of this paper was to study the effect of Wubi Shanyao Pills on sexual dysfunction in rats with kidney-Yang deficiency and to investigate its possible mechanism. Adenine(100 mg·kg~(-1)) was administered to male SD rats for 8 weeks to establish kidney-Yang deficiency model, and at the same time, Wubi Shanyao Pills(2, 1, 0.5 g·kg~(-1)) were administered to rats for 8 weeks. The syndrome manifestation of kidney-Yang deficiency was observed in rats and the scores of symptoms were evaluated. Sexual behavior indexes(incubation period and times of capture, straddle and ejaculation) were measured by mating experiment. The levels of serum testosterone(T), estradiol(E_2), follicle stimulating hormone(FSH), luteinizing hormone(LH), and gonadotropin releasing hormone(GnRH) were measured by radioimmunoassay. The wet weights of testis and seminal vesicle were measured. The content of fructose in seminal plasma was detected by UV spectrophotometry. The pathological changes of testis and epididymis were observed by HE staining. The expression levels of transforming growth factor(TGF-ß1) and cytochrome P450 aromatase(CYP19) in testis were detected by immunohistochemistry and Western blot. The results showed that Wubi Shanyao Pills could significantly reduce the score of kidney-Yang deficiency syndrome, improve the symptoms of kidney-Yang deficiency syndrome, shorten capture, straddle and ejaculation latency, increase capture and straddle times, increase serum T, LH, FSH, E_2 and GnRH levels, increase the wet weight of testis and seminal vesicle and fructose content in seminal plasma, improve the pathological structure of testis and epididymis, and inhibit the expression of TGF-ß1 and increase CYP19 in testis of the model rats. Therefore, Wubi Shanyao Pills can significantly improve sexual dysfunction in rats with kidney-Yang deficiency, and its mechanism may be related to regulating the low function of hypothalamus pituitary gonad(HPG) axis and improving the disorder of sex hormone secretion. In addition, it may be also related to inhibiting the expression of testicular TGF-ß1, increasing the expression of CYP19 protein, and then regulating the amount of T converted to E_2.