Proteomic analysis reveals proteins and pathways associated with declined testosterone production in male obese mice after chronic high-altitude exposure

ObjectiveObesity is common in highland areas owing to lifestyle alterations. There are pieces of evidence to suggest that both obesity and hypoxia may promote oxidative stress, leading to hypogonadism in males. These findings indicate an increased risk of hypogonadism in obese males following hypoxia exposure. However, the mechanisms underlying the disease process remain unclear. The current study aims to explore the mechanism of testosterone production dysfunction in obese male mice exposed to a chronic high-altitude hypoxia environment.MethodsAn obese male mouse model was generated by inducing obesity in mice via a high-fat diet for 14 weeks, and the obese mice were then exposed to a high-altitude hypoxia environment for 24 days. Sera and testicular tissues were collected to detect serum lipids, sex hormone level, and testicular oxidative stress indicators. Morphological examination was performed to assess pathological alterations in testicular tissues and suborganelles in leydig cells. Proteomic alterations in testicular tissues were investigated using quantitative proteomics in Obese/Control and Obese-Hypoxia/Obese groups.ResultsThe results showed that chronic high-altitude hypoxia exposure aggravated low testosterone production in obese male mice accompanied by increased testicular oxidative stress and histological damages. In total, 363 and 242 differentially expressed proteins (DEPs) were identified in the two comparison groups, Obese/Control and Obese-Hypoxia/Obese, respectively. Functional enrichment analysis demonstrated that several significant functional terms and pathways related to testosterone production were altered in the two comparison groups. These included cholesterol metabolism, steroid hormone biosynthesis, peroxisome proliferator-activated receptor (PPAR) signaling pathway, oxidative stress responses, as well as retinol metabolism. Finally, 10 representative DEPs were selected for parallel reaction monitoring verification. Among them, StAR, DHCR7, NSDHL, CYP51A1, FDPS, FDX1, CYP11A1, ALDH1A1, and GPX3 were confirmed to be downregulated in the two groups.ConclusionsChronic hypoxia exposure could exacerbate low testosterone production in obese male mice by influencing the expression of key proteins involved in steroid hormone biosynthesis, cholesterol biosynthesis, oxidative stress responses and retinol metabolism

Biotransformation of doxycycline by \u3ci\u3eBrevundimonas naejangsanensis\u3c/i\u3e and \u3ci\u3eSphingobacterium mizutaii\u3c/i\u3e strains

The fate of doxycycline (DC), a second generation tetracycline antibiotic, in the environment has drawn increasing attention in recent years due to its wide usage. Little is known about the biodegradability of DC in the environment. The objective of this study was to characterize the biotransformation of DC by pure bacterial strains with respect to reaction kinetics under different environmental conditions and biotransformation products. Two bacterial strains, Brevundimonas naejangsanensis DD1 and Sphingobacterium mizutaii DD2, were isolated from chicken litter and characterized for their biotransformation capability of DC. Results show both strains rely on cometabolism to biotransform DC with tryptone as primary growth substrate. DD2 had higher biotransformation kinetics than DD1. The two strains prefer similar pHs (7 and 8) and temperature (30 °C), however, they exhibited opposite responses to increasing background tryptone concentration. While hydrolysis converted DC to its isomer or epimer, the two bacterial strains converted DC to various biotransformation products through a series of demethylation, dehydration, decarbonylation and deamination. Findings from the study can be used to better predict the fate of DC in the environment

The Protective Effects of Ciji-Hua’ai-Baosheng II Formula on Chemotherapy-Treated H22 Hepatocellular Carcinoma Mouse Model by Promoting Tumor Apoptosis

Ciji-Hua’ai-Baosheng II Formula (CHB-II-F) is a traditional Chinese medical formula that has been shown in clinical practice to relieve side effects of chemotherapy and improve quality of life for cancer patients. In order to understand the mechanism of its protective effects on chemotherapy, mice with transplanted H22 hepatocellular carcinoma were employed in this study. Ninety-two mice were injected subcutaneously with H22 HCC cell suspension into the right anterior armpit. After mice were treated with 5-fluorine pyrimidine (5-FU), they were divided into six groups as untreated group, 5-FU group, 5-FU plus Yangzheng Xiaoji Capsule group and three groups of 5-FU plus different concentrations of CHB-II-F. Twenty mice were euthanized after 7 days of treatment in untreated and medium concentration of CHB-II-F groups and all other mice were euthanized after 14 days of treatment. Herbal components/metabolites were analyzed by UPLC-MS. Tumors were evaluated by weight and volume, morphology of light and electron microscope, and cell cycle. Apoptosis were examined by apoptotic proteins expression by western blot. Four major components/metabolites were identified from serum of mice treated with CHB-II-F and they are β-Sitosterol, Salvianolic acid, isobavachalcone, and bakuchiol. Treatment of CHB-II-F significantly increased body weights of mice and decreased tumor volume compared to untreated group. Moreover, CHB-II-F treatment increased tumor cells in G0-G1 transition instead of in S phase. Furthermore, CHB-II-F treatment increased the expression of pro-apoptotic proteins and decreased the expression anti-apoptotic protein. Therefore, CHB-II-F could improve mice general condition and reduce tumor cell malignancy. Moreover, CHB-II-F regulates apoptosis of tumor cells, which could contribute its protective effect on chemotherapy

Murine Missing in Metastasis (MIM) Mediates Cell Polarity and Regulates the Motility Response to Growth Factors

Missing in metastasis (MIM) is a member of the inverse BAR-domain protein family, and in vitro studies have implied MIM plays a role in deforming membrane curvature into filopodia-like protrusions and cell dynamics. Yet, the physiological role of the endogenous MIM in mammalian cells remains undefined.We have examined mouse embryonic fibroblasts (MEFs) derived from mice in which the MIM locus was targeted by a gene trapping vector. MIM(-/-) MEFs showed a less polarized architecture characterized by smooth edges and fewer cell protrusions as compared to wild type cells, although the formation of filopodia-like microprotrusions appeared to be normal. Immunofluorescent staining further revealed that MIM(-/-) cells were partially impaired in the assembly of stress fibers and focal adhesions but were enriched with transverse actin filaments at the periphery. Poor assembly of stress fibers was apparently correlated with attenuation of the activity of Rho GTPases and partially relieved upon overexpressing of Myc-RhoA(Q63L), a constitutively activated RhoA mutant. MIM(-/-) cells were also spread less effectively than wild type cells during attachment to dishes and substratum. Upon treatment with PDGF MIM(-/-) cells developed more prominent dorsal ruffles along with increased Rac1 activity. Compared to wild type cells, MIM(-/-) cells had a slower motility in the presence of a low percentage of serum-containing medium but migrated normally upon adding growth factors such as 10% serum, PDGF or EGF. MIM(-/-) cells were also partially impaired in the internalization of transferrin, fluorescent dyes, foreign DNAs and PDGF receptor alpha. On the other hand, the level of tyrosine phosphorylation of PDGF receptors was more elevated in MIM depleted cells than wild type cells upon PDGF treatment.Our data suggests that endogenous MIM protein regulates globally the cell architecture and endocytosis that ultimately influence a variety of cellular behaviors, including cell polarity, motility, receptor signaling and membrane ruffling

Nutrient Stoichiometry and Plant Life Cycle: Relationships between nitrogen : phosphorus ratio and trait expression of grassland species

Anthropogenic activities interfere with the nitrogen (N) and phosphorus (P) biogeochemical cycles globally, and cause various environmental issues. The relative contribution of N and P in eutrophication is controversial. Although many studies point to N as the key element in the eutrophication process, others found that the main focus should be on P when dealing with eutrophication. Furthermore, while common species favor N-limited environments, field observations indicate that threatened or endangered species frequently persist in P-limited environments. This stresses the importance of preventing P eutrophication and diminishing P availability. Considering the fact that N deposition may shift the type of nutrient limitation in grassland ecosystems from N limitation to limitation by other resources such as P, it is essential to study plant growth responses to N:P stoichiometry. This thesis aims at unraveling the influences of N:P stoichiometry, i.e. the ratio of available N and P in relation to their consumer’s requirements, on the functional and performance traits of the main life stages of grassland species at individual level, i.e. germination, vegetative growth, sexual reproduction performance, and survival. Several greenhouse experiments and a field survey were carried out to specifically explore the following questions: How does parental N:P stoichiometry influence seed germination success and offspring survival, besides the effect of overall nutrient availability? What is the effect of absolute and relative availability of N and P on vegetative growth, particularly on photosynthesis and tissue formation? What is the influence of absolute and relative availability of N and P on sexual reproduction performance at intraspecific level, as well as at interspecific level? The questions mentioned above will help us understand more in detail how nutrient fertilization affects functioning of grassland species along their life cycle via the effects of N:P stoichiometry, which will possibly provide new information for ecosystem conservation. First, the influence of parental N:P stoichiometry on seed characteristics and offspring survival were studied (chapter 2). The corresponding results of this chapter confirm the suggestion of previous research that the endangered species is able to cope with low P availability by producing larger seeds that maintain high N and P concentrations and have a large germination success. The influence of absolute and relative supply of N and P on maximum light-saturated net photosynthesis (Amax) (source activity) and tissue formation (sink activity) were tested in the following chapter (chapter 3). The corresponding results indicate that mineral nutrient supply rather than source activity is the factor that controls sink activity of grassland species. Moreover, in chapter 4 and 5, the next main life stage, i.e. sexual reproduction performance of grassland species along gradients of N:P stoichiometry were explored at both intra- and interspecific level, by combining a greenhouse experiment and a field survey. Our results show that compared to N limitation, P limitation, and N and P co-limitation generally restricted sexual reproduction performance of the selected grassland species, at both intraspecific and interspecific level. This restriction of P limitation/ co-limitation may possibly hamper dispersal capacity of grassland species. This thesis provides several implications for ecosystem conservation. 1) N:P stoichiometric effects on plants should be explicitly considered when developing conservation strategies for grasslands; 2) It is essential to preserve and restore P-limited grasslands. The results in this thesis that show the significant influence of N:P stoichiometry, especially the restriction of P limitation on different main life phrases of grassland species, underline the importance of considering relative N and P availability apart from absolute N and P availability, for preservation of biodiverse grasslands

Nutrient Stoichiometry and Plant Life Cycle: Relationships between nitrogen : phosphorus ratio and trait expression of grassland species

Anthropogenic activities interfere with the nitrogen (N) and phosphorus (P) biogeochemical cycles globally, and cause various environmental issues. The relative contribution of N and P in eutrophication is controversial. Although many studies point to N as the key element in the eutrophication process, others found that the main focus should be on P when dealing with eutrophication. Furthermore, while common species favor N-limited environments, field observations indicate that threatened or endangered species frequently persist in P-limited environments. This stresses the importance of preventing P eutrophication and diminishing P availability. Considering the fact that N deposition may shift the type of nutrient limitation in grassland ecosystems from N limitation to limitation by other resources such as P, it is essential to study plant growth responses to N:P stoichiometry. This thesis aims at unraveling the influences of N:P stoichiometry, i.e. the ratio of available N and P in relation to their consumer’s requirements, on the functional and performance traits of the main life stages of grassland species at individual level, i.e. germination, vegetative growth, sexual reproduction performance, and survival. Several greenhouse experiments and a field survey were carried out to specifically explore the following questions: How does parental N:P stoichiometry influence seed germination success and offspring survival, besides the effect of overall nutrient availability? What is the effect of absolute and relative availability of N and P on vegetative growth, particularly on photosynthesis and tissue formation? What is the influence of absolute and relative availability of N and P on sexual reproduction performance at intraspecific level, as well as at interspecific level? The questions mentioned above will help us understand more in detail how nutrient fertilization affects functioning of grassland species along their life cycle via the effects of N:P stoichiometry, which will possibly provide new information for ecosystem conservation. First, the influence of parental N:P stoichiometry on seed characteristics and offspring survival were studied (chapter 2). The corresponding results of this chapter confirm the suggestion of previous research that the endangered species is able to cope with low P availability by producing larger seeds that maintain high N and P concentrations and have a large germination success. The influence of absolute and relative supply of N and P on maximum light-saturated net photosynthesis (Amax) (source activity) and tissue formation (sink activity) were tested in the following chapter (chapter 3). The corresponding results indicate that mineral nutrient supply rather than source activity is the factor that controls sink activity of grassland species. Moreover, in chapter 4 and 5, the next main life stage, i.e. sexual reproduction performance of grassland species along gradients of N:P stoichiometry were explored at both intra- and interspecific level, by combining a greenhouse experiment and a field survey. Our results show that compared to N limitation, P limitation, and N and P co-limitation generally restricted sexual reproduction performance of the selected grassland species, at both intraspecific and interspecific level. This restriction of P limitation/ co-limitation may possibly hamper dispersal capacity of grassland species. This thesis provides several implications for ecosystem conservation. 1) N:P stoichiometric effects on plants should be explicitly considered when developing conservation strategies for grasslands; 2) It is essential to preserve and restore P-limited grasslands. The results in this thesis that show the significant influence of N:P stoichiometry, especially the restriction of P limitation on different main life phrases of grassland species, underline the importance of considering relative N and P availability apart from absolute N and P availability, for preservation of biodiverse grasslands

Sexual reproduction trait expressions of grassland species along a gradient of nitrogen: phosphorus stoichiometry

Aims Plant investment in sexual reproduction is affected by nitrogen (N): phosphorus (P) stoichiometry. It has been suggested that an important adaptation to strong P limitation is reduced investment in sexual reproduction. We aim to investigate the specific influence of N:P on sexual reproduction performance within and between grassland species. Methods Eleven grassland species were selected in ten plots covering N limitation, co-limitation and P limitation. Nutrients in soil and above-ground biomass were determined, plus soil pH and soil moisture. A range of sexual reproduction traits were measured as a proxy for investment in sexual reproduction. Results At the intraspecific level: compared with N-limited plots, in P-limited/co-limited plots, flowering time was later, flowering period in individuals was shorter, and number of flowers (inflorescences) per individual was smaller. At the interspecific level, in P-limited/co-limited plots, species had a significantly earlier flowering time and a longer seed stalk and seed panicle, than those in N-limited plots. However, flowering period was shorter and number of flowers (inflorescences) per individual was smaller under P limitation/co-limitation. Moreover, significant correlations between soil pH and soil moisture, and sexual reproduction performance of the selected grassland species were also found. Conclusions P limitation/co-limitation restrict the sexual reproduction of grassland species, which may hamper their dispersal capacity. We recommend future studies further analyze the relationship between soil pH and N:P stoichiometry and the influence of soil pH, as well as soil moisture on sexual reproduction performance of grassland species in addition to analyzing N:P stoichiometry

Sexual reproduction traits of Holcus lanatus L. and Parnassia palustris L. in response to absolute and relative supply of nitrogen and phosphorus

Plant investment in sexual reproduction is affected by absolute and relative nitrogen (N) and phosphorus (P) supply. Reduced investment in reproductive traits has been suggested as an important adaptation to strong P-limitation. We experimentally tested how absolute and relative nutrient supply affected sexual reproduction traits of two grassland species. Seedlings of a common grass (Holcus lanatus) and an endangered forb (Parnassia palustris) were grown from seed from a dune area with low relative P-availability. Plants were grown in a full factorial experiment with three N:P supply ratios (5, 15, 45) and two absolute supply levels of N and P. After one year, a range of traits was measured as a proxy for investment in sexual reproduction. We found that N:P supply ratio did not affect sexual reproduction at low nutrient supply; at high nutrient supply, investment in sexual reproduction was significantly less at higher N:P supply ratios. For Holcus lanatus, N:P supply ratio 45 restricted the increase in sexual reproduction upon increasing nutrient supply. Parnassia palustris survival and flowering were low, especially at N:P supply ratio 15 (no results were available for P. palustris at N:P supply ratio 45 due to the high mortality). Our results highlight that at low nutrient supply N:P ratio rarely affected investment in sexual reproduction traits but at high supply low relative P-supply restricted plants’ sexual reproduction investment

Effects of Land Use and Physicochemical Factors on Phytoplankton Community Structure: The Case of Two Fluvial Lakes in the Lower Reach of the Yangtze River, China

Potential changes in phytoplankton community structure in shallow lakes due to land use could pose a serious threat to ecosystem sustainability and functioning. Nevertheless, this effect has not been analyzed in detail. In this study, we chose two adjacent lakes, the main land use types around them are farmland and forest, respectively. We investigated the spatial differences in the phytoplankton community structure, water quality physicochemical parameters, and land use patterns in the two lakes. The results indicated that the annual average cell density and biomass of phytoplankton in the former were 1.84 times and 2.38 times that of the latter, respectively. The results of Pearson correlation and Redundancy analysis showed that total nitrogen (TN), total phosphorus (TP), water depth (WD), and water temperature (WT) were the main environmental factors influencing the structural changes of phytoplankton communities in the two lakes. The results indicated that different land use patterns, such as farmland and towns around the lake, increase the nitrogen (N) and phosphorus (P) content of the lake, while the forests distributed around the lake can reduce the N and P entering the lake, which is probably the main reason for the spatial difference in the characteristics of phytoplankton communities in the two lakes. Our results highlight that land use significantly affects the community structure of phytoplankton by influencing physicochemical factors in water bodies. Our study can provide guidance for pollution control and water quality management of shallow lakes