A gauge of coral physiology: re-examining temporal changes in Endozoicomonas abundance correlated with natural coral bleaching.

Bacteria contribute to many physiological functions of coral holobionts, including responses to bleaching. The bacterial genus, Endozoicomonas, dominates the microbial flora of many coral species and its abundance appears to be correlated with coral bleaching. However, evidences for decoupling of bleaching and Endozoicomonas abundance changes have also been reported. In 2020, a severe bleaching event was recorded at reefs in Taiwan, providing a unique opportunity to re-examine bleaching-Endozoicomonas association using multiple stony corals in natural environments. In this study, we monitored tissue color and microbiome changes in three coral species (Montipora sp., Porites sp., and Stylophora pistillata) in Kenting National Park, following the bleaching event. All tagged Montipora sp. and Porites sp. recovered from bleaching within 1 year, while high mortality occurred in S. pistillata. Microbiome analysis found no correlation of Endozoicomonas relative abundance and bleaching severity during the sampling period, but found a stronger correlation when the month in which bleaching occurred was excluded. Moreover, Endozoicomonas abundance increased during recovery months in Montipora sp. and Porites sp., whereas in S. pistillata it was nearly depleted. These results suggest that Endozoicomonas abundance may represent a gauge of coral health and reflect recovery of some corals from stress. Interestingly, even though different Endozoicomonas strains predominated in the three corals, these Endozoicomonas strains were also shared among coral taxa. Meanwhile, several Endozoicomonas strains showed secondary emergence during coral recovery, suggesting possible symbiont switching in Endozoicomonas. These findings indicate that it may be possible to introduce Endozoicomonas to non-native coral hosts as a coral probiotic.

Similar but different: Characterization of dddD gene-mediated DMSP metabolism among coral-associated Endozoicomonas.

Endozoicomonas are often predominant bacteria and prominently important in coral health. Their role in dimethylsulfoniopropionate (DMSP) degradation has been a subject of discussion for over a decade. A previous study found that Endozoicomonas degraded DMSP through the dddD pathway. This process releases dimethyl sulfide, which is vital for corals coping with thermal stress. However, little is known about the related gene regulation and metabolic abilities of DMSP metabolism in Endozoicomonadaceae. In this study, we isolated a novel Endozoicomonas DMSP degrader and observed a distinct DMSP metabolic trend in two phylogenetically close dddD-harboring Endozoicomonas species, confirmed genetically by comparative transcriptomic profiling and visualization of the change of DMSP stable isotopes in bacterial cells using nanoscale secondary ion spectrometry. Furthermore, we found that DMSP cleavage enzymes are ubiquitous in coral Endozoicomonas with a preference for having DddD lyase. We speculate that harboring DMSP degrading genes enables Endozoicomonas to successfully colonize various coral species across the globe.

High-resolution spatial and genomic characterization of coral-associated microbial aggregates in the coral Stylophora pistillata.

Bacteria commonly form aggregates in a range of coral species [termed coral-associated microbial aggregates (CAMAs)], although these structures remain poorly characterized despite extensive efforts studying the coral microbiome. Here, we comprehensively characterize CAMAs associated with Stylophora pistillata and quantify their cell abundance. Our analysis reveals that multiple Endozoicomonas phylotypes coexist inside a single CAMA. Nanoscale secondary ion mass spectrometry imaging revealed that the Endozoicomonas cells were enriched with phosphorus, with the elemental compositions of CAMAs different from coral tissues and endosymbiotic Symbiodiniaceae, highlighting a role in sequestering and cycling phosphate between coral holobiont partners. Consensus metagenome-assembled genomes of the two dominant Endozoicomonas phylotypes confirmed their metabolic potential for polyphosphate accumulation along with genomic signatures including type VI secretion systems allowing host association. Our findings provide unprecedented insights into Endozoicomonas-dominated CAMAs and the first direct physiological and genomic linked evidence of their biological role in the coral holobiont.

Microbiome Restructuring: Dominant Coral Bacterium Endozoicomonas Species Respond Differentially to Environmental Changes.

Bacteria in the coral microbiome play a crucial role in determining coral health and fitness, and the coral host often restructures its microbiome composition in response to external factors. An important but often neglected factor determining this microbiome restructuring is the ability of microbiome members to respond to changes in the environment. To address this issue, we examined how the microbiome structure of Acropora muricata corals changed over 9 months following a reciprocal transplant experiment. Using a combination of metabarcoding, genomics, and comparative genomics approaches, we found that coral colonies separated by a small distance harbored different dominant Endozoicomonas-related phylotypes belonging to two different species, including a novel species, "Candidatus Endozoicomonas penghunesis" 4G, whose chromosome-level (complete) genome was also sequenced in this study. Furthermore, the two dominant Endozoicomonas species had different potentials to scavenge reactive oxygen species, suggesting potential differences in responding to the environment. Differential capabilities of dominant members of the microbiome to respond to environmental change can (i) provide distinct advantages or disadvantages to coral hosts when subjected to changing environmental conditions and (ii) have positive or negative implications for future reefs. IMPORTANCE The coral microbiome has been known to play a crucial role in host health. In recent years, we have known that the coral microbiome changes in response to external stressors and that coral hosts structure their microbiome in a host-specific manner. However, an important internal factor, the ability of microbiome members to respond to change, has been often neglected. In this study, we combine metabarcoding, culturing, and genomics to delineate the differential ability of two dominant Endozoicomonas species, including a novel "Ca. Endozoicomonas penghunesis" 4G, to respond to change in the environment following a reciprocal transplant experiment.

MXRA5 Is a Novel Immune-Related Biomarker That Predicts Poor Prognosis in Glioma.

BACKGROUND: Glioma is the most common primary intracranial tumor and is associated with poor prognosis. Identifying effective biomarkers for glioma is particularly important. MXRA5, a secreted glycoprotein, is involved in cell adhesion and extracellular matrix remodeling and has been reported to be expressed in many cancers. However, the role and mechanism of action of MXRA5 in gliomas remain unclear. This study was aimed at investigating the role of MXRA5 at the transcriptome level and its clinical prognostic value. METHODS: In this study, RNA microarray data of 301 glioma patients from the Chinese Glioma Genome Atlas (CGGA) were collected as a training cohort and RNA-seq data of 702 glioma samples from The Cancer Genome Atlas (TCGA) were used for validation. We analyzed the clinical and molecular characteristics as well as the prognostic value of MXRA5 in glioma. In addition, the expression level of MXRA was evaluated in 28 glioma tissue samples. RESULTS: We found that MXRA5 expression was significantly upregulated in high-grade gliomas and IDH wild-type gliomas compared to controls. Receiver operating characteristic (ROC) analysis showed that MXRA5 is a potential marker of the mesenchymal subtype of glioblastoma multiforme (GBM). We found that MXRA5 expression is highly correlated with immune checkpoint molecule expression levels and tumor-associated macrophage infiltration. High MXRA5 expression could be used as an independent indicator of poor prognosis in glioma patients. CONCLUSION: Our study suggests that MXRA5 expression is associated with the clinicopathologic features and poor prognosis of gliomas. MXRA5 may play an important role in the immunosuppressive microenvironment of glioma. As a secreted glycoprotein, MXRA5 is a potential circulating biomarker for glioma, deserving further investigation.

Shifting in the Dominant Bacterial Group Endozoicomonas Is Independent of the Dissociation With Coral Symbiont Algae.

The coral-associated Endozoicomonas are dominant bacteria in the coral holobiont. Their relative abundance usually decreases with heat-induced coral bleaching and is proposed to be positively correlated with Symbiodiniaceae abundance. It remains unclear whether this phenomenon of decreased Endozoicomonas abundance is caused by temperature stress or a decreased abundance of Symbiodiniaceae. This study induced bleaching in the coral Euphyllia glabrescens using a dark treatment over 15 weeks. We examined shifts in Endozoicomonas abundance and experimentally reduced Symbiodiniaceae density. 16S rRNA gene amplicon sequencing was used to characterize the changes in bacterial community (incl. Endozoicomonas) over time, and the 16S rRNA gene copy number of Endozoicomonas was quantified by qPCR. We detected a high abundance of Endozoicomonas in E. glabrescens that underwent dark-induced bleaching. The results reveal that changes in the relative abundance of Endozoicomonas are unrelated to Symbiodiniaceae abundance, indicating that Endozoicomonas can be independent of Symbiodiniaceae in the coral holobiont.

Sugar starvation- and GA-inducible calcium-dependent protein kinase 1 feedback regulates GA biosynthesis and activates a 14-3-3 protein to confer drought tolerance in rice seedlings.

Germination followed by seedling growth constitutes two essential steps in the initiation of a new life cycle in plants, and in cereals, completion of these steps is regulated by sugar starvation and the hormone gibberellin. A calcium-dependent protein kinase 1 gene (OsCDPK1) was identified by differential screening of a cDNA library derived from sucrose-starved rice suspension cells. The expression of OsCDPK1 was found to be specifically activated by sucrose starvation among several stress conditions tested as well as activated transiently during post-germination seedling growth. In gain- and loss-of-function studies performed with transgenic rice overexpressing a constitutively active or RNA interference gene knockdown construct, respectively, OsCDPK1 was found to negatively regulate the expression of enzymes essential for GA biosynthesis. In contrast, OsCDPK1 activated the expression of a 14-3-3 protein, GF14c. Overexpression of either constitutively active OsCDPK1 or GF14c enhanced drought tolerance in transgenic rice seedlings. Hence, our studies demonstrated that OsCDPK1 transduces the post-germination Ca(2+) signal derived from sugar starvation and GA, refines the endogenous GA concentration and prevents drought stress injury, all essential functions to seedling development at the beginning of the life cycle in rice.

Rac1+ cells distributed in accordance with CD 133+ cells in glioblastomas and the elevated invasiveness of CD 133+ glioma cells with higher Rac1 activity.

BACKGROUND: Recent studies have suggested that cancer stem cells are one of the major causes for tumor recurrence due to their resistance to radiotherapy and chemotherapy. Although the highly invasive nature of glioblastoma (GBM) cells is also implicated in the failure of current therapies, it is not clear how glioma stem cells (GSCs) are involved in invasiveness. Rac1 activity is necessary for inducing reorganization of actin cytoskeleton and cell movement. In this study, we aimed to investigate the distribution characteristics of CD133+ cells and Rac1+ cells in GBM as well as Rac1 activity in CD133+ GBM cells, and analyze the migration and invasion potential of these cells. METHODS: A series of 21 patients with GBM were admitted consecutively and received tumor resection in Tianjin Medical University General Hospital during the first half of the year 2011. Tissue specimens were collected both from the peripheral and the central parts for each tumor under magnetic resonance imaging (MRI) navigation guidance. Immunohistochemical staining was used to detect the CD133+ cells and Rac1+ cells distribution in GBM specimens. Double-labeling immunofluorescence was further used to analyze CD133 and Rac1 co-expression and the relationship between CD133+ cells distribution and Rac1 expression. Serum-free medium culture and magnetic sorting were used to isolate CD133+ cells from U87 cell line. Rac1 activation assay was conducted to assess the activation of Rac1 in CD133+ and CD133 - U87 cells. The migration and invasive ability of CD133+ and CD133 - U87 cells were determined by cell migration and invasion assays in vitro. Student's t-test and one-way analysis of variance (ANOVA) test were used to determine statistical significance in this study. RESULTS: In the central parts of GBMs, CD133+ cells were found to cluster around necrosis and occasionally cluster around the vessels under the microscope by immunohistological staining. In the peripheral parts of the tumors, CD133+ cells were lined up along the basement membrane of the vessels and myelinated nerve fibers. Rac1 expression was high and diffused in the central parts of the GBMs, and the Rac1+ cells were distributed basically in accordance with CD133+ cells both in the central and peripheral parts of GBMs. In double-labeling immunofluorescence, Rac1 was expressed in (83.14 ± 4.23)% of CD133+ cells, and CD133 and Rac1 co-expressed cells were located around the vessels in GBMs. Significantly higher amounts of Rac1-GTP were expressed in the CD133+ cells (0.378 ± 0.007), compared to CD133- cells (0.195 ± 0.004) (t = 27.81; P < 0.05). CD133+ cells had stronger ability to migrate (74.34 ± 2.40 vs. 38.72 ± 2.60, t = 42.71, P < 0.005) and invade (52.00 ± 2.28 vs. 31.26 ± 1.82, t = 30.76, P < 0.005), compared to their counterpart CD133- cells in transwell cell migration/invasion assay. CONCLUSIONS: These data suggest that CD133+ GBM cells highly express Rac1 and have greater potential to migrate and invade through activated Rac1-GTP. The accordance of distribution between Rac1+ cells and CD133+ cells in GBMs implies that Rac1 might be an inhibited target to prevent invasion and migration and to avoid malignant glioma recurrence.

[Glioma stem cells enhanced angiogenesis and its relationship with microvessel].

OBJECTIVES: To dynamically observe how glioma stem cells promote the tumor formation and angiogenesis, and to study the correlation between the distribution of glioma stem cells and microvessels within different growth stages of subcutaneous tumor. METHODS: Stem cell medium culture and magnetic activated cell sorting were carried out to obtain CD133+ cells from C6 rat glioma cell line. Sprague Dawley (SD) rat ears model were established to observe glioma stem cells promoting blood vessel formation. Subcutaneous glioma model of C6 and immunohistochemical staining of hypoxia inducible factor-1α (HIF-1α) and CD133 were used to investigate the relationship between distribution of glioma stem cells and microvessels. Expressions of CD133 protein in each stage of the subcutaneous tumor were detected by Western blot. RESULTS: Isolation and identification of glioma stem cells deprived from C6 glioma cell line successfully, the establishment of ears model showed real-time dynamic observation of CD133+ cells involved in angiogenesis and tumor formation. SD rat model of subcutaneous glioma showed the initial of tumor formation, CD133+ cells scattered. With tumor growth, CD133+ cells began to tend to capillaries, in late distributed clusters in perivascular. Meanwhile as tumor growth, CD133 protein expression was gradually increased: the values of Western blot analysis of CD133 expression on 6, 9, 12, 15, 20 d were 0.208±0.004, 0.282±0.003, 0.360±0.004, 0.564±0.135, 0.756±0.007, the differences were significant between different groups (F=2601.681, P<0.01). At a high magnification, the CD133 scores with immunohistochemical staining on 6, 9, 12, 15 d were 0.8±0.4, 2.4±0.5, 4.0 ± 0.7, 6.0±0.7; HIF-1α scores were 0.8±0.4, 2.8±0.8, 5.0±0.7, 6.8±0.4. By Spearman rank correlation analysis found that the relationship between CD133 and HIF-1α expression was positively correlated (r=0.921, P<0.01). CONCLUSIONS: Glioma stem cells promote angiogenesis more than non-stem cells; HIF-1α and its downstream gene product might mediate the distribution of glioma stem cells around the perivascular.

[Role of Rac1 in the SDF-1-induced migration and invasion of human glioma cell line U251].

OBJECTIVE: To explore the role of Rac1 in the SDF-1-induced migration and invasion of glioma cells with a specific Rac1 inhibitor. METHODS: Human glioma cell lines U251 treated with SDF-1 or/and specific Rac1 inhibitor were used. The migration and invasion capacities of cells in 2D cell migration/3D invasion assay were assessed. Western blot was employed to detect the levels of Rac1 and GAPDH in cell lysates and the Rac1 activity measured by Rac1 activation assays. Immunofluorescence was used to identify the expression and intracellular location of Rac1 in U251 cells. RESULTS: SDF-1 significantly increased the migration and invasion capacities of U251 cells (P < 0.05). The stimulation of SDF-1 boosted the activity of Rac1 versus the unstimulated cells (P < 0.05). And Rac1 was recruited to protruding edge in SDF-1-stimulated cells. Inhibition of Rac1 with specific Rac1 inhibitor decreased the migration and invasion capacities of SDF-1-induced U251 cells (P < 0.05). In comparison with the SDF-1 treated group, the activity of Rac1 significantly decreased (P < 0.05) and the recruitment of Rac1 to protruding edge significantly decreased in the NSC23766 pre-treated group. CONCLUSIONS: This study provides novel evidence that Rac1 modulates the SDF-1-induced migration and invasion of glioma cells. It suggests that the inhibition of Rac1 activation may be a new therapeutic target for glioma.

Enhanced invasion in vitro and the distribution patterns in vivo of CD133+ glioma stem cells.

BACKGROUND: Recent studies have suggested that cancer stem cells cause tumor recurrence based on their resistance to radiotherapy and chemotherapy. Although the highly invasive nature of glioblastoma cells is also implicated in the failure of current therapies, it is not clear whether cancer stem cells are involved in invasiveness. This study aimed to assess invasive ability of glioma stem cells (GSCs) derived from C6 glioma cell line and the distribution patterns of GSCs in Sprague-Dawley (SD) rat brain tumor. METHODS: Serum-free medium culture and magnetic isolation were used to gain purely CD133(+) GSCs. The invasive ability of CD133(+) and CD133(-) C6 cells were determined using matrigel invasion assay. Immunohistochemical staining for stem cell markers and luxol fast blue staining for white matter tracts were performed to show the distribution patterns of GSCs in brain tumor of rats and the relationship among GSCs, vessels, and white matter tracts. The results of matrigel invasion assay were estimated using the Student's t test and the analysis of Western blotting was performed using the one-way analysis of variance (ANOVA) test. RESULTS: CD133(+) GSCs (number: 85.3 ± 4.0) were significantly more invasive in vitro than matched CD133(-) cells (number: 25.9 ± 3.1) (t = 14.5, P < 0.005). GSCs invaded into the brain diffusely and located in perivascular niche of tumor-brain interface or resided within perivascular niche next to white fiber tracts. The polarity of glioma cells containing GSCs was parallel to the white matter tracts. CONCLUSIONS: Our data suggest that CD133(+) GSCs exhibit more aggressive invasion in vitro and GSCs in vivo probably disseminate along the long axis of blood vessels and transit through the white matter tracts. The therapies targeting GSCs invasion combined with traditional glioblastoma multiforme therapeutic paradigms might be a new approach for avoiding malignant glioma recurrence.

[Correlation between the distribution of CD133-positive cells and the proliferation of microvessels in glioblastoma multiforme].

OBJECTIVE: To investigate the expression of CD133 and CD34 in different parts of glioblastoma and its margin and explore the invasive path of glioma stem cells within the tumor and surrounding tissue. METHODS: The surgical specimens were collected from the core of mass, junctional zones between tumor and peritumoral edematous areas and edematous areas in 52 patients with glioblastoma. Immunohistochemical cell staining and Western blot were employed to evaluate the expression of CD133 in different specimens while immunohistochemistry was used to detect the CD34-microvessel postforming. A correlation analysis was performed between them. RESULTS: The expression of CD133 was not detected in the control groups while the scores were 7.3 ± 1.4, 5.2 ± 1.1, 2.7 ± 1.0 in junctional zones, tumor cores and edematous areas with immunohistochemistry and 0.79 ± 0.03, 0.38 ± 0.01, 0.20 ± 0.04 with Western blot respectively. There were significant differences between different groups (P < 0.05). Under light microscope, the CD133-positive cells frequently forming perivascular pseudorosettes were dense in junctional zones and mostly clustered near the microvessels in tumor cores and scattered in edematous areas. At a high magnification (200×), the CD34-MVD (/HP) values were 31.3 ± 4.0, 21.8 ± 2.6, 15.3 ± 2.4, 4.7 ± 1.5 respectively in junctional zones, tumor cores, edematous areas and control tissues. Significant differences were also found in these groups (P < 0.05). The expression level of CD133-positive cell was positively correlated with the distribution of CD34-microvessels (r = 0.948, P < 0.05). CONCLUSION: Glioma stem cells tend to assemble in the junctional zones where the microvessels are enriched. There is probably an intimate nourishing relationship with the microvessels. The distribution of glioma stem cells may be related with the invasiveness within glioblastoma.

Expression and Distribution Characteristics of Human Ortholog of Mammalian Enabled (hMena) in Glioma.

OBJECTIVE: To investigate the utility of hMena, a family of enabled/vasodilator-stimulated phosphoprotein (Ena/VASP), we sought to characterize the expression profile and distribution characteristics of hMena in a large panel of glioma samples and determine whether hMena expression levels might correlate with the pathological grade of glioma. METHODS: Sixty-five specimens of glioma with different pathological grades and five control brain tissues were collected. In 6 of the 21 glioblastoma patients, multi-specimens were obtained respectively from the main tumor mass, the junction zone between the tumor and the normal tissue, and adjacent brain tissue 1.5 cm away from the tumor boundary under assistance of neuronavigation system during the operation. Immunohistochemistry was used to detect the expression and distribution characteristics of hMena. hMena expression was analyzed by Western blot in 20 specimens. RESULTS: The hMena expression was negative in control brain tissue but positive in different grades of glioma. The expression rate of hMena was positively correlated with the increasing grade of the World Health Orgnization (WHO) classification (r(s)=0.682, P=0.000). hMena was located in cytoplasm. Positive cells only distributed around the vessels within the tumor mass in low grade glioma, while in high grade glioma, these cells were able to be detected not only in the tumor but also in the boundary zone and adjacent brain parenchyma. In the tumor mass, hMena expressed highly and diffusedly. In the junction zone, hMena positive cells formed radiolitic pattern around the vessels. In adjacent brain parenchyma, single positive cell was scattered. hMena expression was markedly elevated in Grade III and IV glioma compared with Grade II and I. CONCLUSION: Our data suggested that the expression of hMena is closely related to malignant grade of glioma. hMena can label the migrating cells, and indicate the migrating path of glioma cells from the tumor to adjacent tissue along with the vascular basement membranes and tracts of white matter.