Will climate warming of terrestrial ecosystem contribute to increase soil greenhouse gas fluxes in plot experiment? A global meta-analysis.

One of the main manifestations of global climate change is its profound impact on the emission of greenhouse gases from terrestrial soil. Numerous field warming experiments have explored the effects of different temperature rise intensities and durations on soil greenhouse gas fluxes in the growing season of different terrestrial ecosystems. However, the results were inconsistent due to the variations in vegetation, soil, and climatic conditions in different ecosystems. In the present work, we carried meta-analysis to synthesize 99 datasets from 52 field warming experiments in growing seasons of terrestrial ecosystems to evaluate the response of soil greenhouse gas fluxes to global warming. The results showed that warming greatly stimulated soil CO2 in temperate forest and farmland by 12.64% and 25.57%, respectively, significantly increased soil N2O emissions in grassland (27.23%), farmland (44.33%), and shrubland (223.36%), and increased soil CH4 uptake by 57.81% in grasslands. However, no significant impact on the greenhouse gas fluxes in other ecosystems was observed. Generally, short-and medium-term (≤ 3 years) warming can promote soil greenhouse gas fluxes. Also, low temperature and low-medium temperature (≤ 2 °C) significantly promoted N2O emission and CH4 absorption, and medium temperature (2-4 °C) considerably assisted CO2 flux, but high temperature (> 4 °C) had no significant effect on greenhouse gas flux. Our results demonstrated that soil greenhouse gas fluxes in terrestrial ecosystems during the growing season do not increase linearly with the increasing climate warming, and it is still uncertain whether there is acclimatization to long-term climate warming.

Optimization of cerebral organoids: a more qualified model for Alzheimer's disease research.

Alzheimer's disease (AD) is a neurodegenerative disease that currently cannot be cured by any drug or intervention, due to its complicated pathogenesis. Current animal and cellular models of AD are unable to meet research needs for AD. However, recent three-dimensional (3D) cerebral organoid models derived from human stem cells have provided a new tool to study molecular mechanisms and pharmaceutical developments of AD. In this review, we discuss the advantages and key limitations of the AD cerebral organoid system in comparison to the commonly used AD models, and propose possible solutions, in order to improve their application in AD research. Ethical concerns associated with human cerebral organoids are also discussed. We also summarize future directions of studies that will improve the cerebral organoid system to better model the pathological events observed in AD brains.

Human iPSCs derived astrocytes rescue rotenone-induced mitochondrial dysfunction and dopaminergic neurodegeneration in vitro by donating functional mitochondria.

BACKGROUND: Parkinson's disease (PD) is one of the neurodegeneration diseases characterized by the gradual loss of dopaminergic (DA) neurons in the substantia nigra region of the brain. Substantial evidence indicates that at the cellular level mitochondrial dysfunction is a key factor leading to pathological features such as neuronal death and accumulation of misfolded α-synuclein aggregations. Autologous transplantation of healthy purified mitochondria has shown to attenuate phenotypes in vitro and in vivo models of PD. However, there are significant technical difficulties in obtaining large amounts of purified mitochondria with normal function. In addition, the half-life of mitochondria varies between days to a few weeks. Thus, identifying a continuous source of healthy mitochondria via intercellular mitochondrial transfer is an attractive option for therapeutic purposes. In this study, we asked whether iPSCs derived astrocytes can serve as a donor to provide functional mitochondria and rescue injured DA neurons after rotenone exposure in an in vitro model of PD. METHODS: We generated DA neurons and astrocytes from human iPSCs and hESCs. We established an astroglial-neuronal co-culture system to investigate the intercellular mitochondrial transfer, as well as the neuroprotective effect of mitochondrial transfer. We employed immunocytochemistry and FACS analysis to track mitochondria. RESULTS: We showed evidence that iPSCs-derived astrocytes or astrocytic conditioned media (ACM) can rescue DA neurons degeneration via intercellular mitochondrial transfer in a rotenone induced in vitro PD model. Specifically, we showed that iPSCs-derived astrocytes from health spontaneously release functional mitochondria into the media. Mito-Tracker Green tagged astrocytic mitochondria were detected in the ACM and were shown to be internalized by the injured neurons via a phospho-p38 depended pathway. Transferred mitochondria were able to significantly reverse DA neurodegeneration and axonal pruning following exposure to rotenone. When rotenone injured neurons were cultured in presence of ACM depleted of mitochondria (by ultrafiltration), the neuroprotective effects were abolished. CONCLUSIONS: Our studies provide the proof of principle that iPSCs-derived astrocytes can act as mitochondria donor to the injured DA neurons and attenuate pathology. Using iPSCs derived astrocytes as a donor can provide a novel strategy that can be further developed for cellular therapy for PD.

Serum Response Factor Promotes Dopaminergic Neuron Survival via Activation of Beclin 1-Dependent Autophagy.

Serum response factor (SRF), a transcription factor highly expressed in neurons, is involved in neuronal survival and the pathogenesis of some neurodegenerative disorders. The ablation of SRF renders the midbrain dopaminergic (DA) neurons vulnerable to 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine-induced neurotoxicity, however, the underlying mechanisms remain poorly understood. Here, we report decreased SRF levels in the substantia nigra (SN) of rotenone-treated rats that was associated with the loss of tyrosine hydroxylase (TH)-positive neurons. SRF expression was also reduced in rotenone-treated PC12 cells in vitro. In addition, Srf knockdown augmented rotenone-induced toxicity in PC12 cells. In contrast, overexpression of Srf attenuated the cells' sensitivity to rotenone and alleviated rotenone-induced α-synuclein accumulation. The protective effect of SRF was abolished when the expression of autophagy-related proteins Beclin 1 and Atg5 was suppressed. These results suggested that SRF may promote DA neuron survival by regulating autophagy, and thus serves as a critical molecule in PD progression.

[Culture, isolation and identification of new bunyavirus in African green monkey kidney(Vero) cells].

OBJECTIVE: To culture, isolate and identify new bunyavirus in Vero cell line. METHODS: Samples of 164 new bunyavirus positive by real time RT-PCR detection and well preserved serum specimens were selected from cases of fever, thrombocytopenia and leukopenia syndrome (FTLS) in Xinyang, Henan province in 2009 - 2011. These sera were cultured in Vero cell line and new bunyavirus were detected by observing cytopathic effect (CPE), Real-time RT-PCR, indirect immunofluorescence assay (IFA) and thin-section electron microscopy observation. A total of 10 positive PCR products were selected randomly for sequencing and the results were compared with sequence in Genbank. RESULTS: Among 164 FTLS serum specimens cultured in Vero cell line, no special CPE were observed and 67 strains (40.85%) were positive detected by Real-time RT-PCR. Nucleic acid similarity of 10 specimens were 97.8% - 100% and there's also a high similarity (> 99%) between specimens and new bunyavirus isolates (Accession No. HQ141600.1). Among 67 positive strains, 58 of them showed specific fluorescence particles by IFA. The viral particles were observed to be spheres with a diameter of 80 - 100 nm by electron microscopy. CONCLUSION: Vero cell line is suitable for culture, isolation and identification of new bunyavirus.

[The distribution of mast cells in benign and malignant prostate lesions and its biologic significance].

OBJECTIVE: To study the distribution profile of mast cells in benign and malignant prostate lesions and its biologic significance. METHODS: Fifty-three prostate specimens collected from 2000 through 2002 were examined, and the distribution of mast cells were analyzed. The paraffin sections were stained with anti-human mast cell tryptase immunohistologically. The numbers of cells stained with positive results in ten high-power fields were counted, and the mean was calculated. RESULTS: No significant relationship of mast cell distribution to inflammation in benign prostatic hyperplasias was observed. Significant differences between the mean mast cell numbers of intratumoral region and those of peritumoral region were noted (P<0.05). There was statistically significant difference in the mean mast cell numbers between well-differentiated groups and poorly-differentiated groups (P>0.05). CONCLUSION: There exists a relationship between prostate carcinoma tissue and mast cells. Mast cells may inhabit the tumor cells by different pathways.

[Comparing two kinds of labeled streptavidin biotin methods and selecting the best antigen retrieval method].

OBJECTIVE: To compare two kinds of labeled streptavidin biotin(LsAB) methods and provide the optimal method of antigen retrieval. METHODS: The alkaline phosphatase(AP) LsAB method and the horseradish peroxidase (HRP) LsAB method were used to stain anti-tryptase in paraffin embedding tissue of patients with chronic obstructive pulmonary disease (COPD) and their staining effects were compared. The antigens were repaired by high pressure cooking, tryptin digestion and microwave, and the repairing effects were compared. RESULTS: The backgrounds of stained sections were more distinct and the color distinction of nucleus and positive signal were brighter by AP-LsAB, compared with those by HRP-LsAB; the repairing effect of high pressure cooking was better than the repairing effect of tryptin digestion and than that of microwave. CONCLUSION: AP-LsAB and high pressure cooking retrieval were recommended for use in immunohistochemical staining of pulmonary inflammatory tissue.