The gap junctional intercellular communication is no prerequisite for the stabilization of xenobiotic metabolizing enzyme activities in primary rat liver parenchymal cells in vitro

Summary In primary monocultures of adult rat liver parenchymal cells (PC), the activities of the xenobiotic metabolizing enzymes microsomal epoxide hydrolase (mEH_b), soluble epoxide hydrolase (sEH), glutathione S-transferases (GST), and phenolsulfotransferase (ST) were reduced after 7 d to values below 33% of the initial activities. Furthermore, the gap junctional intercellular communication (GJIC), measured after microinjection by dye transfer, decreased from 90% on Day 1 to undetectable values after 5 d in monoculture. Co-culture of PC with nonparenchymal rat liver epithelial cells (NEC) increased (98% on Day 1) and stabilized (82% on Day 7) the homotypic GJIC of PC. Additionally, most of the measured xenobiotic metabolizing enzyme activities were well stabilized over 1 wk in co-culture. Because GJIC is one of several mechanisms playing an important role in cell differentiation, the importance of GJIC for the stabilization of xenobiotic metabolizing enzymes in PC was investigated. PC in monoculture were, therefore, treated with 2% dimethyl sulfoxide (DMSO), a differentiation promoting factor, and 1,1,1-trichloro-2,2,-bis (p-chlorophenyl) ethane (DDT) (10 μg/ml), a liver tumor promotor and inhibitor of GJIC, was given to co-cultures of PC with NEC. DMSO significantly stabilized (68% on Day 7), while DDT significantly inhibited (8% on Day 7) homotypic GJIC of PC in the respective culture systems. In contrast, the activities of mEH_b, sEH, GST, and ST were not affected in the presence of DMSO or DDT. These results lead to the assumption that the differentiation parameters measured in this study (i.e., homotypic GJIC and the activities of xenobiotic metabolizing enzymes) are independently regulated in adult rat liver PC.     

Role of peroxisome proliferator-activated receptor gamma in glucose-induced insulin secretion

Peroxisome proliferator-activated receptor (PPAR) isoforms (α and γ) are known to beexpressed in pancreatic islets as well as in insulin-producing cell lines.Ligands of PPAR have been shoWn toenhance glucose-induced insulin secretion in rat pancreatic islets.However,their effect on insulin secretionis still unclear.To understand the molecular mechanism by which PPAR7 exerts its effect on glucose-induced insulin secretion,we examined the endogenous activity of PPAR isoforms,and studied the PPARyfunction and its target gene expression in INS-1 cells.We found that:(1)endogenous PPARγ was activatedin a ligand-dependent manner in INS-1 cells;(2)overexpression of PPARy in the absence of PPARγ ligandsenhanced glucose-induced insulin secretion,which indicates that the increased glucose-induced insulin secretionis a PPARγ-mediated event;(3)the addition of both PPARγ and retinoid X receptor (RXR) ligands showed asynergistic effect on the augmentation of reporter activity,suggesting that the hetero-dimerization of PPAR7and RXR is required for the regulation of the target genes;(4)PPARs upregulated both the glucose transporter2 (GLUT2) and Cbl-associated protein (CAP) genes in INS-1 cells.Our findings suggest an importantmechanistic pathway in which PPARγ enhances glucose-induced insulin secretion by activating the expressionof GLUT2 and CAP genes in a ligand-dependent manner.     

Effect of phosphatidylglycerol on conformation and micro-environment of tyrosyl residue in photosystem II

The structural aspects in the interaction of phosphatidylglycerol (PG) with photosystem II (PSIl), mainly the effect of PQ on conformation and microenvironment of tyrosine residues of PSIl proteins were studied by Fourier transform infrared (FTIR) spectroscopy. It was found that the binding of PG to PSIl particle induces changes in the conformation and micropolarity of phenol ring in the tyrosine residues. In other words, the PG effect on the PSIl results in blue shift of the stretch vibrational band in the phenol ring from 1620 to 1500 cm-1 with the enhancement of the absorb-ance intensity. Additionally, a new spectrum of hydrogen bond was also observed. The results imply that the hydrogen-bond formation between the OH group of phenol and one of PG might cause changes in the structures of tyrosine residues in PSIl proteins.     

Patterns of ramet population of Iris japonica Thunb. and their effects on herb diversity in different microsites on Jinyun Mountain, China

Spatial patterns of ramet population of Iris japonica Thunb. and their effect on species diversity in the herb layer of 3 microsites (open area of forest edge (OAFE), bamboo forest (BF) and evergreen broad-leaved forest (EBF)) on Jinyun Mountain were studied using spatial pattern, niche and diversity analyses in a combination of population and community methods. The results were as follows: (1) judged by V/m and Morisita index (Iδ), ramet population of I. japonica in 3 microsites all clumped from scale 0.5 m × 0.5 m to 2 m × 2 m; (2) the pattern scale and pattern intensity both gradually decreased on all scales, and the density of ramet population of I. japonica decreased with the increase in canopy density and the decrease in relative photon flux density (RPFD) and R/FR from OAFE to EBF. In OAFE and BF, widespread I. japonica had significantly negative influence on the dominance of original dominant species and on species diversity in the herb layer (p < 0.05), while those influences in EBF were extremely weak. The mechanisms that pattern characteristics of ramet population of I. japonica influence herb diversity in 3 microsites were different. In OAFE, strong regeneration niche (above-ground spatial and below-ground root) and trophic niche (nutrient) competition had significantly negative influence on the species diversity of rare herbs and dwarf herbs. In BF, strong regeneration niche (below-ground root) and trophic niche (above-ground for light and below-ground for nutrient) competition had negative effect on the occurrence of rare species and on the survival of other herb species. In EBF, weak niche competition had little effect on the survival of herb species. Intensity of regeneration niche and trophic niche competition between I. japonica and other herb species is the determinant to the mechanism that ramet population of I. japonica influences herb diversity.     

Effects of permafrost degradation on ecosystems

Permafrost, covering approximately 25% of the land area in the Northern Hemisphere, is one of the key components of terrestrial ecosystem in cold regions. As a product of cold climate, permafrost is extremely sensitive to climate change. Climate warming over past decades has caused degradation in permafrost widely and quickly. Permafrost degradation has the potential to significantly change soil moisture content, alter soil nutrients availability and influence on species composition. In lowland ecosystems the loss of ice-rich permafrost has caused the conversion of terrestrial ecosystem to aquatic ecosystem or wetland. In upland ecosystems permafrost thaw has resulted in replacement of hygrophilous community by xeromorphic community or shrub. Permafrost degradation resulting from climate warming may dramatically change the productivity and carbon dynamics of alpine ecosystems. This paper reviewed the effects of permafrost degradation on ecosystem structure and function. At the same time, we put forward critical questions about the effects of permafrost degradation on ecosystems on Qinghai–Tibetan Plateau, included: (1) carry out research about the effects of permafrost degradation on grassland ecosystem and the response of alpine ecosystem to global change; (2) construct long-term and located field observations and research system, based on which predict ecosystem dynamic in permafrost degradation; (3) pay extensive attention to the dynamic of greenhouse gas in permafrost region on Qinghai–Tibetan Plateau and the feedback of greenhouse gas to climate change; (4) quantitative study on the change of water-heat transport in permafrost degradation and the effects of soil moisture and heat change on vegetation growth.     

Effects of permafrost degradation on ecosystems

Permafrost, covering approximately 25% of the land area in the Northern Hemisphere, is one of the key components of terrestrial ecosystem in cold regions. As a product of cold climate, permafrost is extremely sensitive to climate change. Climate warming over past decades has caused degradation in permafrost widely and quickly. Permafrost degradation has the potential to significantly change soil moisture content, alter soil nutrients availability and influence on species composition. In lowland ecosystems the loss of ice-rich permafrost has caused the conversion of terrestrial ecosystem to aquatic ecosystem or wetland. In upland ecosystems permafrost thaw has resulted in replacement of hygrophilous community by xeromorphic community or shrub. Permafrost degradation resulting from climate warming may dramatically change the productivity and carbon dynamics of alpine ecosystems. This paper reviewed the effects of permafrost degradation on ecosystem structure and function. At the same time, we put forward critical questions about the effects of permafrost degradation on ecosystems on Qinghai–Tibetan Plateau, included: (1) carry out research about the effects of permafrost degradation on grassland ecosystem and the response of alpine ecosystem to global change; (2) construct long-term and located field observations and research system, based on which predict ecosystem dynamic in permafrost degradation; (3) pay extensive attention to the dynamic of greenhouse gas in permafrost region on Qinghai–Tibetan Plateau and the feedback of greenhouse gas to climate change; (4) quantitative study on the change of water-heat transport in permafrost degradation and the effects of soil moisture and heat change on vegetation growth.     

Aerodynamic Characteristics, Power Requirements and Camber Effects of the Pitching-Down Flapping Hovering

The pitching-down flapping is a new type of bionic flapping,which was invented by the author based on previous studieson the aerodynamic mechanisms of fruit fly(pitching-up)flapping.The motivation of this invention is to improve the aerodynamiccharacteristics of flapping Micro Air Vehicles(MAVs).In this paper the pitching-down flapping is briefly introduced.Themajor works include:(1)Computing the power requirements of pitching-down flapping in three modes(advanced,symmetrical,delayed),which were compared with those of pitching-up flapping;(2)Investigating the effects of translational accelerationtime,Δτ_t,and rotational time,Δτ_r,at the end of a stroke,and the angle of attack,α,in the middle of a stroke on the aerodynamiccharacteristics in symmetrical mode;(3)Investigating the effect of camber on pitching-down flapping.From the above works,conclusions can be drawn that:(1)Compared with the pitching-up flapping,the pitching-down flapping can greatly reduce thetime-averaged power requirements;(2)The increase in Δτt and the decrease in Δτ_r can increase both the lift and drag coefficients,but the time-averaged ratio of lift to drag changes a little.And α has significant effect on the aerodynamic characteristicsof the pitching-down flapping;(3)The positive camber can effectively increase the lift coefficient and the ratio of lift to drag.     

Acylceramides and lanosterol-lipid markers of terminal differentiation in cultured human keratinocytes: Modulating effect of retinoic acid

Summary Epidermal differentiation is accompanied by profound changes in the synthesis of a variety of intracellular proteins and intercellular lipids. In conventional, submerged culture keratinocytes have been shown to lose the ability to synthesize the protein markers of differentiation. They re-express them, however, when they are cultured in medium supplemented with delipidized [retinoic acid (RA)-depleted] serum or in air-exposed cultures using de-epidermized dermis (DED) as a substrate. Recent studies have revealed that acylceramides (AC) and lanosterol (LAN), which are present only in trace amounts in cultures of keratinocytes grown under submerged conditions on DED in medium supplemented with normal serum, become expressed in significant amounts when the culture is lifted to the air-liquid interface. Inasmuch as culture conditions may markedly affect the extent of keratinocyte differentiation, the present study aimed to investigate the effect of normal (RA-containing) or delipidized (RA-depleted) serum and of RA administration on lipid composition (especially of the AC and LAN contents) in cells cultured under submerged and air-exposed conditions. To test a possible effect of dermal substrate (used in the air-exposed model), the lipid composition of keratinocytes grown under submerged conditions on a plastic and on a dermal substrate (de-epidermized dermis, DED) has also been compared. The results revealed that under all culture conditions, RA deprivation of fetal bovine serum resulted in a marked increase of total ceramide content. Even under submerged conditions, the presence of both AC and LAN could be detected. In air-exposed culture, the content of these lipids was markedly increased. Addition of RA at 1 μM concentration to cultures grown in RA-depleted medium induced marked changes in lipid composition under all culture conditions tested. In cells grown under submerged conditions (both on plastic and on DED) AC and LAN were no longer present in detectable amounts. Also in air-exposed culture, a marked decrease in the content of these lipids was observed. These results suggest that liposoluble serum components, like RA, control the synthesis of lipids that are present in later stages of epidermal differentiation.     

Expression and regulation of mRNAs for insulin-like growth factor-I receptor and LH receptor in corpora lutea

Relationship between insulin-like growth factor-l receptor (IGF-IR) and luteinizing hormone receptor (LHR) mRNA expression as well as their regulation was determined in rat corpora lutea (CL) . In the CL of estrous cycle rat, LHR mRNA positive CL expressed high level of mRNA of IGF-IR. While the expression of LHR mRNA decreased on estrus, the CL still expressed relatively high level of IGF-IR mRNA. In pseudopregnant rat CL, the expression level of LHR mRNA was low on day 1, the most intense signals were detected on day 8, the signals of LHR mRNA became undetectable on day 14. In contrast to LHR expression, the high level of IGF-IR mRNA was observed in pseudopregnant CL of day 1, and thereafter its signals were detected from day 2 to day 14. Pregnant rat CL expressed both LHR and IGF-IR mRNAs. IGF-I stimulated LHR expression in CL. PGF2ainhibited expression of IGF-IR and LHR. PGE2 negated the inhibiting effects of PGF2α. These data suggest that IGF-I may be involved in regulating CL function, and maintai     

Diversity and distribution patterns of non-volant smallmammals along different elevation gradients on Mt. Kenya,Kenya

The distribution of small mammals in mountainous environments across different elevations can provide important information on the effects of climate change on the dispersal of species. However, few studies conducted on Afromontane ecosystems have compared the altitudinal patterns of small mammal diversity. We investigated the species diversity and abundance of non-volant small mammals(hereafter ‘small mammals')on Mt. Kenya, the second tallest mountain in Africa,using a standard sampling scheme. Nine sampling transects were established at intervals of 200 m on the eastern(Chogoria) and western(Sirimon) slopes.A total of 1 905 individuals representing 25 species of small mammals were trapped after 12 240 trap-nights.Abundance was highest at mid-elevations on both slopes.However, species richness and their distribution patterns differed between the two slopes. More species were recorded on Chogoria(24) than on Sirimon(17). On Chogoria, species richness was higher at mid-high elevations, with a peak at mid-elevation(2 800 m a.s.l.),whereas species richness showed little variation on the Sirimon slope. These results indicate that patterns of species diversity can differ between slopes on the same mountain. In addition, we extensively reviewed literature on Mt. Kenya's mammals and compiled a comprehensive checklist of 76 mammalian species. However, additional research is required to improve our understanding of smal mammal diversity in mountain habitats in Africa.     

Cell Wall Lignin is Polymerised by Class Ⅲ Secretable Plant Peroxidases in Norway Spruce

Class Ⅲ secretable plant peroxidases occur as a large family of genes in plants with many functions and probable redundancy. In this review we are concentrating on the evidence we have on the catalysis of lignin polymerization by class Ⅲ plant peroxidases present in the apoplastic space in the xylem of trees. Some evidence exists on the specificity of peroxidase isozymes in lignin polymerization through substrate specificity studies, from antisense mutants in tobacco and poplar and from tissue and cell culture lines of Norway spruce (Picea abies) and Zinnia elegans. In addition, real time (RT-)PCR results have pointed out that many peroxidases have tissue specific expression patterns in Norway spruce. Through combining information on catalytic properties of the enzymes, on the expression patterns of the corresponding genes, and on the presence of monolignols and hydrogen peroxide in the apoplastic space, we can show that specific peroxidases catalyze lignin polymerization in the apoplastic space of Norway spruce xylem.     

Phylogenetic Relationship of Dendranthema （DC.） Des Moul. Revealed by Fluorescent In Situ Hybridization

Phylogenetic relationships of the different species in the genus Dendranthema (DC.) Des Moul. were estimated based on chromosome fluorescent in situ hybridization (FISH) with 18S-26S rDNA of Arabidopsis and genomic DNA of Dendranthema as probes. The results revealed that there was no positive correlation between the number of nuclear organization region (NOR) loci and the ploidy of Dendranthema.The exact cytogenetic information of NORs about 14 operational taxonomic units (OTUs) indicated that D.vestitum (Hemsl.) Ling et Shih was closer to the cultivars than other putative species, whereas D. zawadskii (Herb.) Tzvel. was the most distinct. The ambiguously distributed signals of genomic in situ hybridization (GISH) with genomic DNA of lower ploidy species as probes suggested that different genomes among Dendranthema were mixed. The result also indicated the limitation of GISH in studies on the phylogenetic relationships of the different species in this genus Dendranthema and on the origin of cultivated chrysanthemums. Based on these results and previous research, the origin of Chinese cultivated chrysanthemum is discussed.     

Influence of the Chamfer on the Flexural Properties of Beetle Elytron Plates

To improve the flexural properties of Beetle Elytron Plates(BEPs)and clarify the effect of the transition arcs(chamfers)between the skins and the trabeculae,the chamfers were set in BEPs,and then the influence of the chamfer on BEPs'mechanical properties was investigated via experimentation and the Finite Elemnent Method simulation(FEM).The results indicate that the influence of the chamfer on the flexural properties and ductility was most obvious in the Trabecular Beetle Elytron Plates(TBEPs),less obvious in the Honeycomb Plates(HPs)and basically no efiect was observed on End-trabecular Beetle Elytron Plates(EBEPs).The chamfer can improve the mechanical stability of EBEPSs.As the chamfer diameter increased in the BEPs,the length of the residual trabecular root on the skin increased when failure occurred in the TBEPs.The crack position in the honeycomb wallsof the HPs gradually shifted from the skin to the center.The EBEPs continued to exhibit oblique cracks.From the perspective of the force characteristics of these BEPs.combined with numerical simulation,the influence mechanism of the chamfer on their flcxural propertics was investigated.     

Physical mapping of three fruit ripening genes：Endopolygalacturonase,ACC oxidase and ACC synthase from apple（Malus x domestica） in an apple rootstock A106（Malus sieboldii

The apple rootstock,A106(Malus sieboldii),had 17 bivalents in pollen mother cells at meiotic metaphase 1,and 17 chromosomes in a haploid pollen cell.Karyotypes were prepared from root-tip cells with 2n=34 chromosomes,Seven out of 82 karyotypes(8.5%) showed one pari of satellites at the end of the short arm of chromosome 3.C-bands were shown on 6 pairs of chromosomes 2,4,6,8,14,and 16 near the telomeric regions of short arms.Probes for three ripening-related genes from Malus x domestica:endopolygalacturonase(EPG,0.6kb),ACC oxidase(1.2kb),and ACC synthase(2kb)were hybridized in situ to metaphase chromosomes of A106.Hybridization sites for the EPG gene were observed on the long arm of chromosome 14 in 15 out of 16 replicate spreads and proximal to the centromere of chromosomes 6 and 11.For the ACC oxidase gene,hylridization sites were observed in the telomeric region of the short arm of chromosomes 5 and 11 in 87% and 81% of 16 spreads respectively,proxiaml to the centromere of chromosome 1 in 81% of the spreads,and on the long arm of chromosome 13 in 50% of the spreads. Physical mapping of three fruit ripening genes in an apple rootstock A106.Twenty five spreads were studied for the ACC synthase gene and hybridization sites were observed in the telomeric region of the short arm of chromosome 12 in 96% of the spreads.chromosomes 9 and 10 in 76% of the spreads,and chromosome 17 in 56% of the spreads.     

Academician of Academia Sinica:Biographical Sketch of Prof.C.L.Tsou(Chenglu Zou)

C.L.Tsou( Chenglu Zou) was born on May 1 7,1 92 3in Jiangsu,China.He received his B.Sc.in1 945from the chemistry department of The National Southwest Associated University in Kunming andwas awarded a Ph.D.( Biochemistry) from the University of Cambridge,England in 1 951 .He was aResearch Associate then Professor and Head of Enzyme Division of the Shanghai Institute of Biochemistry,Academia Sinica.He moved to Beijing in1 970 to the Institute of Biophysics and was its Deputy Direc…     

Effects of Interaction Between Cadmium and Plumbum on Phytochelatins and Glutathione Production in Wheat （Triticum aestivum L.）

Phytochelatins (PCs) may function as a potential biomarker for metal toxicity. However, less attention has been paid to the effects of metal interactions on the production of PCs and glutathione (GSH), the most prominent cellular thiol. In the present study, the effects of interactions between cadmium (Cd) and plumbum (Pb) on the production of PCs and GSH were monitored over a period of 14 d in wheat (Triticum aestivum L.) tissues. The results showed that combination of Cd and Pb led to synergistic growth inhibition in wheat. Exposure to Cd or Pb increased levels of PCs in a concentration-, tissue-, and time-dependent manner. Cadmium was more effective that Pb in increasing PCs production. Compared with the effects of Cd or Pb alone on the production of PCs, the combination of Cd and Pb acted synergistically, resulting in an enhanced production of PCs. Cadmium also stimulated GSH production in a concentration-, tissue-, and time-dependent manner. However, Pb had no obvious effects on GSH levels. The combination of Pb and Cd antagonized GSH production over the course of the growth period. The results of the present study suggest that metal interactions should be considered in the application of PCs and GSH as potential biomarkers for the evaluation of metal toxicity.     

Cytotoxicity and genome-wide microarray analysis of intestinal smooth muscle cells in response to hexavalent chromium induction

Chronic ingestion of high concentrations of hexavalent chromium Cr(VI) in drinking water induces intestinal tumors in mice; however, information on its toxicity on intestinal smooth muscle cells is limited. The present study aimed to assess the in vitro and in vivo toxicological effects of Cr(VI) on intestinal smooth muscle cells. Human intestinal smooth muscle cells (HISM cells) were cultured with different concentrations of Cr(VI) to evaluate effects on cell proliferation ability, oxidative stress levels, and antioxidant system. Furthermore, tissue sections in Cr(VI) exposed rabbits were analyzed to evaluate toxicity on intestinal muscle cells in vivo. Gene chips were utilized to assess differential gene expression profiles at the genome-wide level in 1 μmol/L Cr(VI) treated cells. Intestinal tissue biopsy results showed that Cr(VI) increased the incidences of diffuse epithelial hyperplasia in intestinal jejunum but caused no obvious damage to the structure of the muscularis. Cell proliferation analysis revealed that high concentrations (≥64 μmol/L) but not low concentrations of Cr(VI) (≤16 μmol/L) significantly inhibited the growth of HISM cells. For oxidative stress levels, the expression of reactive oxygen species (ROS) and nitric oxide (NO) was elevated at high concentrations (≥64 μmol/L) but not at low concentrations of Cr(VI) (≤16 μmol/L). In addition, dose-dependent increases in the activity of oxidized glutathione (GSSH)/total-glutathione (T-GSH) were also observed. Gene chip screened 491 differentially expressed genes including genes associated with cell apoptosis, oxidations, and cytoskeletons. Some of these differentially expressed genes may be unique to smooth muscle cells in response to Cr(VI) induction.