Dissolved organic matter, calcium ion and extracellular polymeric substances on living associated bacteria of Microcystis colony are crucial for unicellular Microcystis to efficiently form colonies.

Microcystis typically forms colonies under natural conditions, which contributes to occurrence and prevalence of algal blooms. The colonies consist of Microcystis and associated bacteria (AB), embedded in extracellular polymeric substances (EPS). Previous studies indicate that AB can induce Microcystis to form colonies, however the efficiency is generally low and results in a uniform morphotype. In this study, by using filtrated natural water, several AB strains induced unicellular M. aeruginosa to form colonies resembling several Microcystis morphotypes. The mechanisms were investigated with Methylobacterium sp. Z5. Ca2+ was necessary for Z5 to induce Microcystis to form colonies, while dissolved organic matters (DOM) facilitated AB to agglomerate Microcystis to form large colonies. EPS of living Z5, mainly the aromatic protein components, played a key role in colony induction. Z5 initially aggregated Microcystis via the bridging effects of Ca2+ and DOM, followed by the induction of EPS synthesis and secretion in Microcystis. In this process, the colony forming mode shifted from cell adhesion to a combination of cell adhesion and cell division. Intriguingly, Z5 drove the genomic rearrangement of Microcystis by upregulating some transposase genes. This study unveiled a novel mechanism about Microcystis colony formation and identified a new driver of Microcystis genomic evolution.

High-titer AAV disrupts cerebrovascular integrity and induces lymphocyte infiltration in adult mouse brain.

The brain is often described as an "immune-privileged" organ due to the presence of the blood-brain-barrier (BBB), which limits the entry of immune cells. In general, intracranial injection of adeno-associated virus (AAV) is considered a relatively safe procedure. In this study, we discovered that AAV, a popular engineered viral vector for gene therapy, can disrupt the BBB and induce immune cell infiltration in a titer-dependent manner. First, our bulk RNA sequencing data revealed that injection of high-titer AAV significantly upregulated many genes involved in disrupting BBB integrity and antiviral adaptive immune responses. By using histologic analysis, we further demonstrated that the biological structure of the BBB was severely disrupted in the adult mouse brain. Meanwhile, we noticed abnormal leakage of blood components, including immune cells, within the brain parenchyma of high-titer AAV injected areas. Moreover, we identified that the majority of infiltrated immune cells were cytotoxic T lymphocytes (CTLs), which resulted in a massive loss of neurons at the site of AAV injection. In addition, antagonizing CTL function by administering antibodies significantly reduced neuronal toxicity induced by high-titer AAV. Collectively, our findings underscore potential severe side effects of intracranial injection of high-titer AAV, which might compromise proper data interpretation if unaware of.

AP-HTPB propellant combustion under strain conditions with laser absorption spectroscopy.

Understanding the combustion behaviors of solid propellant with different levels of strains is of practical interest. In this work, an experimental study of the effects of static and dynamic strains on the burning rate, temperature, CO, and C O 2 formation of aluminized ammonium perchlorate (AP)-hydroxyl terminated poly-butadiene (HTPB) propellant combustion was presented at initial pressures of 0.1 MPa, 0.2 MPa, and 0.5 MPa. The strains were being applied onto solid propellant by exerting static and cyclic loadings. The propellant burning rate was acquired by a 4 kHz high-speed photography system, and the combustion temperature, CO, and C O 2 column densities were measured at 10 kHz through laser absorption spectroscopy (LAS). At atmospheric pressure, it was demonstrated that the propellant burning rate increased with tensile stress and decreased with compressive stress. The measured flame temperature showed a similar correlation with strains as compared to the propellant burning rate. At elevated pressures, the increase of the propellant burning rate due to tensile stress was more evident, while the difference in combustion temperatures was less significant. For the cyclic strain condition, the variations of the measured C O 2 and CO column densities were consistent with the static strain condition.

Region-specific distribution of Olig2-expressing astrocytes in adult mouse brain and spinal cord.

Olig2 is an important transcription factor essential for the specification and differentiation of oligodendrocytes as well as astrocytes and neurons during developmental stages. However, Olig2 distribution pattern and its relationship among different types of glial cells in the adult central nervous system (CNS) are not well characterized. Here, we systematically examined Olig2 expression pattern in combination with major markers of neurons and glial cells throughout the brain and spinal cord in the adult mice. As expected, Olig2 is universally expressed in oligodendrocytes and oligodendrocyte precursor cells (OPCs), but not in neurons or microglia. Interestingly, we discover a subpopulation of Olig2+ astrocytes that are highly enriched in some specific regions including the olfactory bulb, thalamus, midbrain, medulla, and spinal cord in the adult mice. Moreover, OPCs have high expression level of Olig2, whereas oligodendrocytes and astrocytes have similar level of Olig2 expression. Our results suggest that a distinct population of Olig2+ astrocytes are highly concentrated in discrete regions in the adult CNS. Investigating the functional significance of these Olig2+ astrocytes in both resting state and pathological state of the brain and spinal cord may broaden our understanding on astrocytic heterogeneity and functions.

Targeting Myeloid-Derived Suppressor Cell, a Promising Strategy to Overcome Resistance to Immune Checkpoint Inhibitors.

Immune checkpoint inhibitors (ICIs) are starting to transform the treatment for patients with advanced cancer. The extensive application of these antibodies for various cancer obtains exciting anti-tumor immune response by activating T cells. Although the encouraging clinical benefit in patients receiving these immunostimulatory agents are observed, numbers of patients still derive limited response or even none for reasons unknown, sometimes at the cost of adverse reactions. Myeloid-derived suppressor cells (MDSCs) is a heterogeneous immature population of myeloid cells partly influencing the efficacy of immunotherapies. These cells not only directly suppress T cell but mediate a potently immunosuppressive network within tumor microenvironment to attenuate the anti-tumor response. The crosstalk between MDSCs and immune cells/non-immune cells generates several positive feedbacks to negatively modulate the tumor microenvironment. As such, the recruitment of immunosuppressive cells, upregulation of immune checkpoints, angiogenesis and hypoxia are induced and contributing to the acquired resistance to ICIs. Targeting MDSCs could be a potential therapy to overcome the limitation. In this review, we focus on the role of MDSCs in resistance to ICIs and summarize the therapeutic strategies targeting them to enhance ICIs efficiency in cancer patients.

A novel mutation combining with rs66612022 in a Chinese pedigree suggests a new pathogenesis to osteogenesis imperfecta via whole genome sequencing.

Osteogenesis imperfecta (OI) is a rare heritable disease with systemic connective tissue disorder. Most of the patients represent autosomal dominant form of OI, and are usually resulting from the mutations in type I collagen genes. However, the gene mutations reported previously only account for ∼70% of the OI cases. Here, in a Chinese OI family, we examined seven patients and nine normal individuals using the whole genome sequencing and molecular genetic analysis. The mutation of rs66612022 (COL1A2:p.Gly328Ser) related to glycine substitution was found in the seven patients. Moreover, we identified a novel missense mutation (HMMR:p.Glu2Gln). Interestingly, the individuals of this family with both the mutations were suffering from OI, while the others carried one or none of them are normal. The mutations of COL1A2 and HMMR and their combined effect on OI would further expand the genetic spectrum of OI.

[Effect of pregnant rat adipose-derived stem cells on repair of acute liver injury].

Objective: To assess the effect of pregnant rat adipose-derived stem cells (ADSCs) on repair of acute liver injury. Methods: ADSCs were isolated from 18-week pregnant Sprague Dawley rats and were identified by flow cytometry. Twenty Sprague Dawley rats were randomly divided into groups A, B, C, and D ( n=5); rats in group A were not treated as normal controls; rats in groups B, C, and D were injected intraperitoneally with CCl 4 to establish the acute liver injury model. At 2 hours after modeling, DPBS, 0.1 mL normal rat ADSCs (2×10 6cells/mL), and pregnant rat ADSCs (2×10 6cells/mL) were injected into the spleen in groups A, C, and D respectively; rats in group B was not treated. After 7 days, total bilirubin (TBIL), alanine aminotransferase (ALT), aspartic acid transaminase (AST), albumin (ALB), and total protein (TP) in serum were measured. The liver tissue sections were stained with HE. The expressions of Ki67, alpha-fetoprotein (AFP), and ALB were measured by immunohistochemistry. Results: The serum levels of TBIL, ALT, and AST in group B were significantly higher than those in groups A, C, and D ( P<0.05), but ALB and TP were significantly lower than those in groups A, C, and D ( P<0.05). The levels of TBIL, ALT, and AST were significantly higher in groups C and D than group A, and in group C than group D ( P<0.05). There was no significant difference in serum levels of ALB among groups A, C, and D ( P>0.05). The serum level of TP in groups C and D was significantly lower than that in group A ( P<0.05), but no significant difference was found between group C and group D ( P>0.05). HE staining showed that the liver tissue of group A had clear structure; the cells arranged neatly with uniform size. The hepatocytes in group B showed obvious edema, disorderly arrangement, dot necrosis in liver lobules, and diffuse infiltration of inflammatory cells. In groups C and D, the inflammation and hepatocellular necrosis were obviously reduced when compared with group B, and the number of vacuoles caused by dilation of mitochondria and rough endoplasmic reticulum was decreased; especially in group D, improvement of liver injury was more effective. The Ki67 positive cell rate was significantly higher in groups C and D than groups A and B ( P<0.05), in group B than group A ( P<0.05), and in group D than group C ( P<0.05). There was no expression of AFP in groups A and B, but positive expression was observed in groups C and D, and AFP positive cell rate of group D was significantly higher than that of group C ( t=3.006, P=0.017). ALB expression was significantly higher in groups C and D than groups A and B ( P<0.05), and in group D than group C ( P<0.05). Conclusion: Pregnant rat ADSCs could promote repair of liver injury induced by CCl 4.

[EXPRESSION OF RECEPTOR ACTIVATOR OF NUCLEAR FACTOR-κB LIGAND IN PERIPHERAL BLOOD OF PATIENTS WITH ASEPTIC LOOSENING OF THE IMPLANT AFTER TOTAL HIP APTHROPLASTY].

OBJECTIVE: To investigate the expression changes of the receptor activator of nuclear factor-κB ligand (RANKL) in the peripheral blood of patients with aseptic loosening of the implant after total hip arthroplasty (THA) by comparing with that of patients with femoral neck fracture and to analyze the correlation between RANKL expression and aseptic loosening. METHODS: Between January 2008 and January 2013, the peripheral blood were harvested from 58 patients with aseptic loosening of the implant after THA (trial group) and 63 patients with femoral neck fracture (control group). The 2 groups were well matched, with no significant differences in age and gender (P > 0.05). The expressions of the RANKL mRNA and RANKL protein were evaluated by quantitative real-time PCR and Western blot respectively. At the same time, the concentration of RANKL was also measured by ELISA. RESULTS: The expression of the RANKL mRNA in the trial group was 18.30 ± 1.09, which was significantly higher than that of control group (1.00 ± 0.05) (t = 125.390, P = 0.000). The relative RANKL protein expression values in trial group and control group were 0.856 ± 0.254 and 0.404 ± 0.102 respectively, showing significant difference (t = 13.032, P = 0.000). The results of ELISA showed that the concentration of RANKL in trial group [(3.553 5 ± 0.129 7) ng/mL] was significantly higher than that of control group [(1.912 3 ± 0.126 2) ng/ mL] (t = 18.124, P = 0.000). CONCLUSION: The high RANKL expression in peripheral blood is probably correlated with aseptic loosening of the implant in patients undergoing THA, which possibly is the prognostic factor of aseptic loosening of the implant.