Ecological Stoichiometry of Microbial Biomass Carbon, Nitrogen and Phosphorus on Bauxite Residue Disposal Areas
GEOMICROBIOLOGY JOURNAL
Authors: Cheng, Qingyu; Xue, Rui; Wu, Hao; Hartley, William; Zhang, Yifan; Zhou, Lean; Xue, Shengguo
Abstract
Ecological succession by microbial activity on bauxite residue disposal areas (BRDAs) would accumulate nutrients and convert the residue into a soil-like material. However, the role of microorganisms in nutrient cycling remains elusive on BRDAs. Carbon (C), nitrogen (N) and phosphorus (P) ecological stoichiometry is a critical indicator of nutrient cycling in an ecosystem. In order to investigate the changes in nutrients following long-term natural weathering process, the contents of C, N, P, microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP) were measured in chronological stacks of bauxite residue. Deeply, their ecological stoichiometric characteristics were analyzed. Compared to freshly stacked residue, organic carbon (OC), total nitrogen (TN) and available phosphorus (AP) have increased 89%, 1640%, and 369% after 20 years, respectively. The C/N in 20-year-old residue (BR20) is 12.41, which close to the mean range of soil C/N in China. Bauxite residue C/P and N/P increased significantly with the stacking age increased. MBC/MBN decreased from 6.75 to 4.52 after stacked for 5 years, whilst MBC/MBP increased from 23.74 to 59.16 with stacking age. Data analysis of C, N, P and MBC, MBN, MBP in bauxite residue correlated significantly, indicating that microbial biomass can be used as a biological indicator to evaluate bauxite residue quality. This study revealed that BRDAs ecosystem development reaches homeostasis gradually, whilst CNP and MBCNP substrate ratio can be used as an effective tool to explore the mechanism of nutrient cycling.
\FTY720-Mitoxy reduces synucleinopathy and neuroinflammation, restores behavior and mitochondria function, and increases GDNF expression in Multiple System Atrophy mouse models
EXPERIMENTAL NEUROLOGY
Authors: Vidal-Martinez, Guadalupe; Segura-Ulate, Ismael; Yang, Barbara; Diaz-Pacheco, Valeria; Barragan, Jose A.; Esquivel, Jocelyn De-Leon; Chaparro, Stephanie A.; Vargas-Medrano, Javier; Perez, Ruth G.
Abstract
Multiple system atrophy (MSA) is a fatal disorder with no effective treatment. MSA pathology is characterized by a-synuclein (aSyn) accumulation in oligodendrocytes, the myelinating glial cells of the central nervous system (CNS). aSyn accumulation in oligodendrocytes forms the pathognomonic glial cytoplasmic inclusions (GCIs) of MSA. MSA aSyn pathology is also associated with motor and autonomic dysfunction, including an impaired ability to sweat. MSA patients have abnormal CNS expression of glial-cell-line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF). Our prior studies using the parent compound FTY720, a food and drug administration (FDA) approved immunosuppressive for multiple sclerosis, reveal that FTY720 protects parkinsonian mice by increasing BDNF. Our FTY720-derivative, FTY720-Mitoxy, is known to increase expression of oligodendrocyte BDNF, GDNF, and nerve growth factor (NGF) but does not reduce levels of circulating lymphocytes as it is not phosphorylated so cannot modulate sphingosine 1 phosphate receptors (S1PRs). To preclinically assess FTY720-Mitoxy for MSA, we used mice expressing human aSyn in oligodendrocytes under a 2,' 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) promoter. CNP-aSyn transgenic (Tg) mice develop motor dysfunction between 7 and 9 mo, and progressive GCI pathology. Using liquid chromatography-mass spectrometry (LC-MS/MS) and enzymatic assays, we confirmed that FTY720-Mitoxy was stable and active. Vehicle or FTY720-Mitoxy (1.1 mg/kg/day) was delivered to wild type (WT) or Tg littermates from 8.5-11.5 mo by osmotic pump. We behaviorally assessed their movement by rotarod and sweat production by starch-iodine test. Postmortem tissues were evaluated by qPCR for BDNF, GDNF, NGF and GDNF-receptor RET mRNA and for aSyn, BDNF, GDNF, and Ibal protein by immunoblot. MicroRNAs (miRNAs) were also assessed by qPCR. FTY720-Mitoxy normalized movement, sweat function and soleus muscle mass in 11.5 mo Tg MSA mice. FTY720-Mitoxy also increased levels of brain GDNF and reduced brain miR-96-5p, a miRNA that acts to decrease GDNF expression. Moreover, FTY720-Mitoxy blocked aSyn pathology measured by sequential protein extraction and immunoblot, and microglial activation assessed by immunohistochemistry and immunoblot. In the 3-nitropropionic acid (3NP) toxin model of MSA, FTY720-Mitoxy protected movement and mitochondria in WT and CNP-aSyn Tg littermates. Our data confirm potent in vivo protection by FTY720-Mitoxy, supporting its further evaluation as a potential therapy for MSA and related synucleinopathies.