A1 astrocytes contribute to murine depression-like behavior and cognitive dysfunction, which can be alleviated by IL-10 or fluorocitrate treatment.

BACKGROUND: Astrocytes are crucial regulators in the central nervous system. Abnormal activation of astrocytes contributes to some behavior deficits. However, mechanisms underlying the effects remain unclear. Here, we studied the activation of A1 astrocytes and their contribution to murine behavior deficits. METHODS: A1 astrocytes were induced by treatment with lipopolysaccharide (LPS) in vitro. The functional phenotype of astrocytes was determined by quantitative RT-PCR, ELISA, and immunohistochemistry. To assess the role of A1 astrocytes in vivo, mice were injected intraperitoneally with LPS. Then, murine behaviors were tested, and the hippocampus and cortex were analyzed by quantitative RT-PCR, ELISA, and immunohistochemistry. The function of IL-10 and fluorocitrate on A1 astrocyte activation was also examined. RESULTS: Our results show that astrocytes isolated from B6.129S6-Il10tm1Flv/J homozygotes (IL-10tm1/tm1) were prone to characteristics of A1 reactive astrocytes. Compared with their wild-type counterparts, IL-10tm1/tm1 astrocytes exhibited higher expression of glial fibrillary acidic protein (GFAP). Whether or not they were stimulated with LPS, IL-10tm1/tm1 astrocytes exhibited enhanced expression of A1-specific transcripts and proinflammatory factors IL-1ß, IL-6, and TNFα. In addition, IL-10tm1/tm1 astrocytes demonstrated hyperphosphorylation of STAT3. Moreover, astrocytes from IL-10tm1/tm1 mice showed attenuated phagocytic ability and were neurotoxic. IL-10tm1/tm1 mice demonstrated increased immobility time in the forced swim test and defective learning and memory behavior in the Morris water maze test. Moreover, enhanced neuroinflammation was found in the hippocampus and cortex of IL-10tm1/tm1 mice, accompanying with more GFAP-positive astrocytes and severe neuron loss in the hippocampus. Pretreatment IL-10tm1/tm1 mice with IL-10 or fluorocitrate decreased the expression of proinflammatory factors and A1-specific transcripts in the hippocampus and cortex, and then alleviated LPS-induced depressive-like behavior. CONCLUSION: These results demonstrate that astrocytes isolated from B6.129S6-Il10tm1Flv/J homozygotes are prone to A1 phenotype and contribute to the depression-like behavior and memory deficits. Inhibiting A1 astrocyte activation may be an attractive therapeutic strategy in some neurodegenerative diseases.

Effects of XIST/miR-137 axis on neuropathic pain by targeting TNFAIP1 in a rat model.

Non-coding RNAs have been reported to participate in the pathophysiology of neuropathic pain. The objective of our study was to investigate the biological role of XIST in neuropathic pain development. In our study, we identify and validate that lncRNA XIST was markedly increased and miR-137 was significantly decreased in chronic constriction injury (CCI) rats. XIST silencing alleviated pain behaviors including both mechanical and thermal hyperalgesia in the CCI rats. XIST was predicted to interact with miR-137 by bioinformatics technology and dual-luciferase reporter assays confirmed the correlation between XIST and miR-137. miR-137 was negatively modulated by XIST and upregulation of miR-137 greatly reduced neuropathic pain development in CCI rats. Moreover, we observed that tumor necrosis factor alpha-induced protein 1 (TNFAIP1) was enhanced in CCI rats and 3'-untranslated region (UTR) of TNFAIP1 was exhibited to be a target of miR-137 by bioinformatics prediction. TNFAIP1 can act as a crucial inflammation regulator by activating NF-kB activity. Overexpression of miR-137 significantly suppressed TNFAIP1 both in vitro and in vivo. Furthermore, upregulation of XIST reversed the inhibitory role of miR-137 in neuropathic pain development by inhibiting TNFAIP1. In conclusion, our current study indicates that XIST can positively regulate neuropathic pain in rats through regulating the expression of miR-137 and TNFAIP1. Our results imply that XIST/miR-137/TNFAIP1 axis may serve as a novel therapeutic target in neuropathic pain.

[Spatial distribution patterns and intraspecific and interspecific spatial associations of Quercus myrsinifolia population in Shennongjia, China]. / ç¥žå†œæž¶å°å¶é’å†ˆç§ç¾¤çš„ç©ºé—´åˆ†å¸ƒæ ¼å±€åŠç§å† ç§é—´ç©ºé—´å ³è”.

Quercus myrsinifolia is one of the dominant species in the evergreen broad-leaf forest on the southern slope of Shennongjia. The study of spatial distribution pattern and spatial correlation of Q. myrsinifolia population will help to understand population development and potential ecological processes, as well as the structure and biodiversity maintenance mechanism of evergreen broad-leaf forests at the northern edge of the subtropics. Based on forest dynamic monitoring data from one 1 hm2 permanent plot on the southern slope of Shennongjia, we employed pair correlation functions g(r) and marked correlation functions to analyze the diameter structure of the Q. myrsinifolia population, spatial distribution patterns at different diameter classes, and intraspecific and interspecific spatial associations. The results showed that diameter structure of Q. myrsinifolia population exhibited an inverted 'J'-shaped distribution, suggesting a healthy regeneration status and belonging to a growing population type. The spatial distribution showed a decreasing trend in aggregation with increasing diameter. Positive correlations among individuals strengthened with closer diameter classes, while weakening with larger diameter differences. Interspecific spatial associations showed an increasing correlation of Q. myrsinifolia with understory dominant species with increasing spatial scales, but no correlation was observed with canopy-dominant species. Our results suggested that the spatial pattern of Q. myrsinifolia populations on the southern slope of Shennongjia was mainly influenced by habitat filtering, seed dispersal limitation, and intraspecific and interspecific competition. Furthermore, the adaptive strategies of Q. myrsinifolia varied when they coexisted with different species.

Clinical relevance of genetic polymorphisms in WNT signaling pathway (SFRP1, WNT3A, CTNNB1, WIF-1, DKK-1, LRP5, LRP6) on pulmonary tuberculosis in a Chinese population.

The present study was performed to evaluate the association of WNT signaling pathway genes variants with pulmonary tuberculosis (PTB) risk in Chinese Han population. Our study subjects were composed of 452 PTB patients and 465 normal controls, and seventeen SNPs of seven genes in WNT signaling pathway (SFRP1, WNT3A, CTNNB1, WIF-1, DKK-1, LRP5, LRP6) were genotyped by SNPscan technique. We found no significant relationship of SFRP1 rs10088390, rs4736958, rs3242, WNT3A rs752107, rs3121310, CTNNB1 rs2293303, rs1798802, rs4135385, WIF-1 rs1026024, rs3782499, DKK-1 rs2241529, rs1569198, LRP5 rs3736228, rs556442, LRP6 rs2302685, rs11054697, rs10743980 polymorphisms with PTB susceptibility. While, WIF-1 rs3782499 variant was associated with susceptibility to PTB under recessive model, and haplotype analysis showed that DKK-1 GA haplotype frequency was significantly increased in PTB patients. The WNT3A rs3121310, CTNNB1 rs2293303 polymorphisms were respectively associated with drug-induced liver injury (DILI), sputum smear-positive in PTB patients. The rs3782499 in WIF-1 gene was related to fever, leukopenia, and the rs1569198 in DKK-1 was linked to sputum smear-positive in PTB patients. In LRP5 gene, rs3736228, rs556442 variants respectively affected the occurrence of DILI, fever, and LRP6 gene rs2302685, rs10743980 variants respectively influenced the development of hypoproteinemia, sputum smear-positive in PTB patients. Our results revealed that WNT signaling pathway genes variation were not associated with the susceptibility to PTB, while WNT3A, CTNNB1, WIF-1, DKK-1, LRP5, LRP6 genetic variations might be closely related to the occurrence of several clinical characteristics of PTB patients.

Validation of the intact zwittermicin A biosynthetic gene cluster and discovery of a complementary resistance mechanism in Bacillus thuringiensis.

Zwittermicin A (ZmA) is a hybrid polyketide-nonribosomal peptide produced by certain Bacillus cereus group strains. It displays broad-spectrum antimicrobial activity. Its biosynthetic pathway in B. cereus has been proposed through analysis of the nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) modules involved in ZmA biosynthesis. In this study, we constructed a bacterial artificial chromosome (BAC) library from Bacillus thuringiensis subsp. kurstaki strain YBT-1520 genomic DNA. The presence of known genes involved in the biosynthesis of ZmA in this BAC library was investigated by PCR techniques. Nine positive clones were identified, two of which (covering an approximately 60-kb region) could confer ZmA biosynthesis ability upon B. thuringiensis BMB171 after simultaneous transfer into this host by two compatible shuttle BAC vectors. Another previously unidentified gene cluster, named zmaWXY, was found to improve the yield of ZmA and was experimentally defined to function as a ZmA resistance transporter which expels ZmA from the cells. Putative transposase genes were detected on the flanking regions of the two gene clusters (the ZmA synthetic cluster and zmaWXY), which suggests a mobile nature of these two gene clusters. The intact ZmA gene cluster was validated, and a resistance mechanism complementary to that for zmaR (the previously identified ZmA self-resistance gene) was revealed. This study also provided a straightforward strategy to isolate and identify a huge gene cluster from Bacillus.

Coupled-cavity concept applied to a highly compact single-frequency laser operating in the 2 µm spectral region.

We present a highly compact and cost-efficient Tm:YAP laser setup supporting single-frequency operation at a significantly high efficiency. The coupled-cavity concept was used to design a single-frequency laser operating at 1990 nm. Single-frequency output power of 784 mW was obtained when the absorbed pumping power was 2.4 W. The optical-to-optical efficiency was 33%, and the slope efficiency was 52%.

Function of histone H2B monoubiquitination in transcriptional regulation of auxin biosynthesis in Arabidopsis.

The auxin IAA is a vital plant hormone in controlling growth and development, but our knowledge about its complicated biosynthetic pathways and molecular regulation are still limited and fragmentary. cytokinin induced root waving 2 (ckrw2) was isolated as one of the auxin-deficient mutants in a large-scale forward genetic screen aiming to find more genes functioning in auxin homeostasis and/or its regulation. Here we show that CKRW2 is identical to Histone Monoubiquitination 1 (HUB1), a gene encoding an E3 ligase required for histone H2B monoubiquitination (H2Bub1) in Arabidopsis. In addition to pleiotropic defects in growth and development, loss of CKRW2/HUB1 function also led to typical auxin-deficient phenotypes in roots, which was associated with significantly lower expression levels of several functional auxin synthetic genes, namely TRP2/TSB1, WEI7/ASB1, YUC7 and AMI1. Corresponding defects in H2Bub1 were detected in the coding regions of these genes by chromatin immunoprecipitation (ChIP) analysis, indicating the involvement of H2Bub1 in regulating auxin biosynthesis. Importantly, application of exogenous cytokinin (CK) could stimulate CKRW2/HUB1 expression, providing an epigenetic avenue for CK to regulate the auxin homeostasis. Our results reveal a previously unknown mechanism for regulating auxin biosynthesis via HUB1/2-mediated H2Bub1 at the chromatin level.

Phenotypic plasticity of stomatal and photosynthetic features of four Picea species in two contrasting common gardens.

Global climate change is expected to affect mountain ecosystems significantly. Phenotypic plasticity, the ability of any genotype to produce a variety of phenotypes under different environmental conditions, is critical in determining the ability of species to acclimate to current climatic changes. Here, to simulate the impact of climate change, we compared the physiology of species of the genus Picea from different provenances and climatic conditions and quantified their phenotypic plasticity index (PPI) in two contrasting common gardens (dry vs. wet), and then considered phenotypic plastic effects on their future adaptation. The mean PPI of the photosynthetic features studied was higher than that of the stomatal features. Species grown in the arid and humid common gardens were differentiated: the stomatal length (SL) and width (SW) on the adaxial surface, the transpiration rate (Tr) and leaf mass per area (LMA) were more highly correlated with rainfall than other traits. There were no significant relationships between the observed plasticity and the species' original habitat, except in P. crassifolia (from an arid habitat) and P. asperata (from a humid habitat). Picea crassifolia exhibited enhanced instantaneous efficiency of water use (PPI = 0.52) and the ratio of photosynthesis to respiration (PPI = 0.10) remained constant; this species was, therefore, considered to the one best able to acclimate when faced with the effects of climate change. The other three species exhibited reduced physiological activity when exposed to water limitation. These findings indicate how climate change affects the potential roles of plasticity in determining plant physiology, and provide a basis for future reforestation efforts in China.

Influencing factors of postoperative early delayed gastric emptying after minimally invasive Ivor-Lewis esophagectomy.

BACKGROUND: The main clinical treatment for esophageal cancer is surgery. Since traditional open esophageal cancer resection has the disadvantages of large trauma, long recovery period, and high postoperative complication rate, its clinical application is gradually reduced. The current report of minimally invasive Ivor-Lewis esophagectomy (MIILE) is increasing. However, researchers found that patients with MIILE had a higher incidence of early delayed gastric emptying (DGE). AIM: To investigate the influencing factors of postoperative early DGE after MIILE. METHODS: A total of 156 patients diagnosed with esophageal cancer at Deyang People's Hospital were enrolled. According to the criteria of DGE, patients were assigned to a DGE group (n = 49) and a control group (n = 107). The differences between the DGE group and the control group were compared. Multivariate logistic regression analysis was used to further determine the influencing factors of postoperative early DGE. The receiver operating characteristic (ROC) curve was used to assess potential factors in predicting postoperative early DGE. RESULTS: Age, intraoperative blood loss, chest drainage time, portion of anxiety score ≥ 45 points, analgesia pump use, postoperative to enteral nutrition interval, and postoperative fluid volume in the DGE group were higher than those in the control group. Perioperative albumin level in the DGE group was lower than that in the control group (P < 0.05). Age, anxiety score, perioperative albumin level, and postoperative fluid volume were independent factors influencing postoperative early DGE, and the differences were statistically significant (P < 0.05). The ROC curve analysis revealed that the area under the curve (AUC) for anxiety score was 0.720. The optimum cut-off value was 39, and the sensitivity and specificity were 80.37% and 65.31%, respectively. The AUC for postoperative fluid volume were 0.774. The optimal cut-off value was 1191.86 mL, and the sensitivity and specificity were 65.3% and 77.6%, respectively. The AUC for perioperative albumin level was 0.758. The optimum cut-off value was 26.75 g/L, and the sensitivity and specificity were 97.2% and 46.9%, respectively. CONCLUSION: Advanced age, postoperative anxiety, perioperative albumin level, and postoperative fluid volume can increase the incidence of postoperative early DGE.

miR-129-5p Regulates the Immunomodulatory Functions of Adipose-Derived Stem Cells via Targeting Stat1 Signaling.

Adipose-derived stem cells (ASCs) have become one of the most promising stem cell populations for cell-based therapies in regenerative medicine and for autoimmune disorders owing to their multilineage differentiation and immunomodulatory capacities, respectively. One advantage of ASC-based therapy lies in their immunosuppressive potential. However, how to get ASCs to provide consistent immunosuppression remains unclear. In the current study, we found that miR-129-5p was induced in ASCs treated with inflammatory factors. ASCs with miR-129-5p knockdown exhibited enhanced immunosuppressive capacity, as evidenced by reduced expression of proinflammatory factors, with concurrent increased expression of inducible nitric oxide synthases (iNOS) and nitric oxide (NO) production. These cells also had an increased capacity to inhibit T cell proliferation in vitro. ASCs with miR-129-5p knockdown alleviated inflammatory bowel diseases and promoted tumor growth in vivo. Consistently, ASCs that overexpressed miR-129-5p exhibited reduced iNOS expression. Furthermore, we show that miR-129-5p knockdown in ASCs results in hyperphosphorylation of signal transducer and activator of transcription 1 (Stat1). When fludarabine, an inhibitor of Stat1 activation, was added to ASCs with miR-129-5p knockdown, iNOS mRNA and protein levels were significantly reduced. Collectively, these results reveal a new role for miR-129-5p in regulating the immunomodulatory activities of ASCs by targeting Stat1 activation. These novel insights into the mechanisms of ASC immunoregulation may lead to the consistent production of ASCs with strong immunosuppressive functions and thus better clinical utility of these cells.

[Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia for lumbar disc herniation in elder with systemic diseases].

OBJECTIVE: To explore the clinical effect of percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia for lumbar disc herniation in elder with systemic diseases. METHODS: The clinical data of 44 elder patients with lumbar disc herniation and systemic diseases treated from June 2013 to June 2017 were retrospectively analyzed. Including 26 males and 18 females, aged 70 to 86 years old with an average of(77.5±3.5) years, course of disease was 3 weeks to 6 months. Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia was performed in the patients. Postoperative straight leg-raising degree change and Nakai criteria were used to evaluate the operative effect. Visual analogue scale(VAS) and JOA scoring system were used to compare the symptom improvement between preoperative and postoperative. RESULTS: No serious complications occurred during and after the operation, and the coexisting medical diseases were not aggravated. All patients safely survived the perioperative period. All the 44 cases were followed up from 6 to 30 months with an average of 20 months. Postoperative straight leg raising angle was obviously improved. At final follow-up, according to Nakai standard, 41 cases got excellent results, 3 good. VAS scores were significantly decreased and JOA scores were significantly increased in final follow-up(P<0.01). CONCLUSIONS: Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia is a safe, effective, less invasive technique for the treatment of lumbar disc herniation in elder with systemic diseases. Multidisciplinary collaboration and perioperative well controlled disease are essential for early rehabilitation of such patients.

[Display of avian influenza virus nucleoprotein on Bacillus thuringiensis cell surface].

S-layer protein CTC surface display system of Bacillus thuringiensis (Bt) was used to test the possibility of displaying avian influenza virus nucleoprotein (NP) on Bt cell surface. Four recombinant plasmids were constructed by replacing 3'-terminal or central part below the surface anchor sequence slh of S-layer protein gene ctc with full length of np gene or part np gene (npp). The four resulting plasmids were pSNP (harboring fusion gene ctc-np), pCSA-SNP (harboring fusion gene csa-ctc-up, csa represents csaAB operon which is very important to the anchoring of S-layer protein on the bacterial cell surface), pCTC-NPP (harboring fusion gene ctc-npp) and pCSNPP (harboring fusion gene csa-ctc-npp). Five recombinant Bt strains were constructed by electro-transferring recombinant plasmids to Bt plasmid-free derivative strain BMB171. The resulting strains were BN (harboring pSNP), BCN (harboring pSNP as well as the plasmid pMIL-CSA which carried csaAB operon), C-S (harboring pCSA-SNP), BCCN (harboring pCTC-NPP and pMIL-CSA) and CN (harboring pCSNPP). The vegetative cells of five recombinant strains were used as agglutinogens of slide agglutination assay. Slide agglutination assay showed recombinant NP proteins were successfully displayed on the surface of five recombinant strains, respectively. After immunizing mice with vegetative cells of five recombinant strains respectively, five recombinant strains all elicited humoral respones to NP and exhibited immunogenicity as assayed by enzyme-linked immunosorbent assay (ELISA). Meanwhile these assays showed recombinant strain CN (harboring fusion gene csa-ctc-npp) exhibited the highest immunogenicity among five recombinant strains. That means the best way of constructing S-layer fusion gene is csa-ctc-* (* denotes heterologous antigen gene) which means the central part of S-layer protein gene ctc replaced by the heterologous antigen gene and csaAB operon located on the upstream of fusion gene. The strategy developed in this study gives a possibility to generate heat stable,oral, veterinary vaccine with Bt S-layer protein CTC surface display system.

[Research progress on the mechanisms and influence factors of nitrogen retention and transformation in riparian ecosystems.] / æ¶ˆè½å¸¦ç”Ÿæ€ç³»ç»Ÿæ°®ç´ æˆªç•™è½¬åŒ–çš„ä¸»è¦æœºåˆ¶åŠå½±å“å› ç´ .

Riparian zone, the ecological transition buffer between terrestrial and aquatic ecosystems (rivers, lakes, reservoirs, wetlands, and other specific water bodies) with unique eco-hydrological and biogeochemical processes, is the last ecological barrier to prevent ammonium, nitrate and other non-point nitrogen pollutants from adjacent water bodies. Based on a summary of current progress of related studies, we found there were two major mechanisms underpinning the nitrogen retention/removal by the riparian ecosystems: 1) the relative locations of nitrogen in the soil-plant-atmosphere continuum system could be altered by riparian vegetation; 2) nitrogen could also be denitrified and then removed permanently by microorganisms in riparian soil. However, which process is more critical for the nitrogen removal remains elusive. Due to large variances of hydro-dynamic, vegetation, microbial, and soil substrate properties in nitrogen retention and transformation with various watersheds, it's difficult to identify which factor is the most important one driving nitrogen cycle in the riparian ecosystems. It is also found that the limitation of study methods, paucity of data at large spatial and temporal scale, and no consensus on the riparian width, are the three major reasons leading to large variances of the results among studies. In conclusion, it is suggested that further efforts should be focused on: 1) the detailed analysis on the successive environmental factors with long-term; 2) the application of a comprehensive method combining mathematical models, geographic information system, remote sensing and quantified technique (such as the coupled technique of the isotopic tracer and gas exchange measurement); 3) the implementation of studies at large temporal and spatial scales. It is sure that, these efforts can help to optimize the nitrogen removal pathways in the riparian ecosystems and provide scientific basis for ecosystem management.

[Co-expression of crystal protein gene cry26Aa and cry28Aa has an ability to form parasporal crystal inside exosporium in Bacillus thuringiensis subsp. finitimus].

Parasporal crystal in Bacillus thuringiensis subsp. finitimus T02 forms within the exosporium and remains attached to the spore after mother cell lysis, which leads to spore-crystal connection. According to the crystal protein gene sequence in B. thuringiensis subsp. finitimus, cry26 and cry28 were cloned from strain T02 by PCR amplification and transformed into the crystal negative Bacillus thuringiensis strain BMB171 by shuttle vectors, alone or in combination together. Crystal can be observed inside of exosporium when co-expression of these two genes. But crystal mainly formed outside of exosporium when they expressed alone. This suggests interaction between of the two crystal proteins may be involved in enclosure.

Higher thermal acclimation potential of respiration but not photosynthesis in two alpine Picea taxa in contrast to two lowland congeners.

The members of the genus Picea form a dominant component in many alpine and boreal forests which are the major sink for atmospheric CO2. However, little is known about the growth response and acclimation of CO2 exchange characteristics to high temperature stress in Picea taxa from different altitudes. Gas exchange parameters and growth characteristics were recorded from four year old seedlings of two alpine (Picea likiangensis vars. rubescens and linzhiensis) and two lowland (P. koraiensis and P. meyeri) taxa. Seedlings were grown at moderate (25°C/15°C) and high (35°C/25°C) day/night temperatures, for four months. The approximated biomass increment (ΔD2H) for all taxa decreased under high temperature stress, associated with decreased photosynthesis and increased respiration. However, the two alpine taxa exhibited lower photosynthetic acclimation and higher respiratory acclimation than either lowland taxon. Moreover, higher leaf dry mass per unit area (LMA) and leaf nitrogen content per unit area (Narea), and a smaller change in the nitrogen use efficiency of photosynthesis (PNUE) for lowland taxa indicated that these maintained higher homeostasis of photosynthesis than alpine taxa. The higher respiration rates produced more energy for repair and maintenance biomass, especially for higher photosynthetic activity for lowland taxa, which causes lower respiratory acclimation. Thus, the changes of ΔD2H for alpine spruces were larger than that for lowland spruces. These results indicate that long term heat stress negatively impact on the growth of Picea seedlings, and alpine taxa are more affected than low altitude ones by high temperature stress. Hence the altitude ranges of Picea taxa should be taken into account when predicting changes to carbon fluxes in warmer conditions.

ß2-Adrenergic signal transduction plays a detrimental role in subchondral bone loss of temporomandibular joint in osteoarthritis.

The present study tested whether activation of the sympathetic tone by aberrant joint loading elicits abnormal subchondral bone remodeling in temporomandibular joint (TMJ) osteoarthritis. Abnormal dental occlusion was created in experimental rats, which were then intraperitoneally injected by saline, propranolol or isoproterenol. The norepinephrine contents, distribution of sympathetic nerve fibers, expression of ß-adrenergic receptors (ß-ARs) and remodeling parameters in the condylar subchondral bone were investigated. Mesenchymal stem cells (MSCs) from condylar subchondral bones were harvested for comparison of their ß-ARs, pro-osteoclastic gene expressions and pro-osteoclastic function. Increases in norepinephrine level, sympathetic nerve fiber distribution and ß2-AR expression were observed in the condylar subchondral bone of experimental rats, together with subchondral bone loss and increased osteoclast activity. ß-antagonist (propranolol) suppressed subchondral bone loss and osteoclast hyperfunction while ß-agonist (isoproterenol) exacerbated those responses. MSCs from experimental condylar subchondral bone expressed higher levels of ß2-AR and RANKL; norepinephrine stimulation further increased their RANKL expression and pro-osteoclastic function. These effects were blocked by inhibition of ß2-AR or the PKA pathway. RANKL expression by MSCs decreased after propranolol administration and increased after isoproterenol administration. It is concluded that ß2-AR signal-mediated subchondral bone loss in TMJ osteoarthritisis associated with increased RANKL secretion by MSCs.

Differential drought tolerance in tree populations from contrasting elevations.

To predict the ecological consequences of climate change for a widely distributed tree species, it is essential to develop a deep understanding of the ecophysiological responses of populations from contrasting climates to varied soil water availabilities. In the present study, we focused on Pinus tabuliformis, one of the most economically and ecologically important tree species in China. In a greenhouse experiment, we exposed trees from high-elevation (HP) and low-elevation (LP) populations to low (80 % of field capacity, FC), mild (60 % FC), moderate (40 % FC) and severe (20 % FC) water stresses. Leaf gas exchange, biomass production and allocation, as well as water-use efficiency, were measured during the experiment. Increasing soil water stress clearly decreased the relative growth rate (RGR), total dry mass (TDM), light-saturated photosynthetic rate (Asat), stomatal conductance (gs), total water use (TWU) and whole-plant water-use efficiency (WUEWP). In contrast, intrinsic water-use efficiency (WUEi) and carbon isotope composition (δ(13)C) both increased significantly with increasing soil water stress for both populations. Only in the LP did the root/shoot ratio (R/S ratio) significantly increase when the water stress increased. A strong positive correlation between Asat and gs coupled with a reduced intercellular CO2 concentration (Ci) probably suggested that stomatal limitations were the main cause of the decreased Asat. However, all the measured variables from the HP were affected less by drought compared with those of the LP, and most aspects of the HP were canalized against drought stress, which was reflected by the relatively higher RGR, TDM and WUEWP. Overall, the results suggest that the two populations responded differentially to drought stress with the HP showing higher drought tolerance than the LP, which was reflected by its faster seedling growth rate and more efficient water use under drought conditions.

Trade-offs between the metabolic rate and population density of plants.

The energetic equivalence rule, which is based on a combination of metabolic theory and the self-thinning rule, is one of the fundamental laws of nature. However, there is a progressively increasing body of evidence that scaling relationships of metabolic rate vs. body mass and population density vs. body mass are variable and deviate from their respective theoretical values of 3/4 and -3/4 or -2/3. These findings questioned the previous hypotheses of energetic equivalence rule in plants. Here we examined the allometric relationships between photosynthetic mass (M(p)) or leaf mass (M(L)) vs. body mass (beta); population density vs. body mass (delta); and leaf mass vs. population density, for desert shrubs, trees, and herbaceous plants, respectively. As expected, the allometric relationships for both photosynthetic mass (i.e. metabolic rate) and population density varied with the environmental conditions. However, the ratio between the two exponents was -1 (i.e. beta/delta = -1) and followed the trade-off principle when local resources were limited. Our results demonstrate for the first time that the energetic equivalence rule of plants is based on trade-offs between the variable metabolic rate and population density rather than their constant allometric exponents.