A microporous anionic metal–organic framework for aqueous encapsulation and highly reversible sensitization of light-emitting Tb3+ ions

An anionic porous material can serve as both a host and an antenna for protecting and sensitizing extra-framework light-emitting Eu3+/Tb3+ ions. The Tb3+ uptake and release is a reversible process and the cationic Tb3+ can be gradually released.

[Effect of imatinib on the height of children with chronic myeloid leukemia in the chronic phase]

目的

评估伊马替尼对慢性髓性白血病慢性期（CML-CP）儿童身高的影响。

方法

2018年7月至2019年7月，在全国范围内对诊断时年龄<18周岁、接受伊马替尼治疗至少3个月的CML儿童或其家长发放问卷，调查受访者伊马替尼治疗前后身高的变化。主要评价指标为身高标准差积分值（HtSDS）以及标准差积分的差值（ΔHtSDS），并分析其相关影响因素。

结果

共有238例受访者符合标准并被纳入研究，男性138例（58.0％），初诊时中位年龄11.0（1.4～17.9）岁，青春期前93例（39.0％），至填写答卷时，中位年龄15.0（2.0～34.0）岁，中位伊马替尼服药时间28（3～213）个月。受访者填写答卷时HtSDS（−0.063±1.361）较治疗前HtSDS（0.391±1.244）显著下降（P<0.001），71.0％的患儿出现身高增长减慢。青春期前服药者治疗后HtSDS下降显著（P<0.05），而青春期开始后服药者HtSDS变化不明显（P>0.05）。多因素分析显示，服药初始年龄较小（偏回归系数为0.122，B＝0.572，t＝10.733，P<0.001）和服药时间较长（偏回归系数为−0.006，B＝−0.211，t＝−4.062，P<0.001）是伊马替尼抑制身高增长的独立影响因素。

结论

伊马替尼引起CML-CP儿童身高增长障碍，服药初始年龄越小、服药时间越长，伊马替尼对身高的影响越明显。

Revealing the contribution of Cytochrome P450 to salt-sensitive hypertension using DNA microarray

BACKGROUND

Salt sensitivity is an important cause of hypertension which is a major public health problem. This study aimed to investigate the contribution of Cytochrome P450 (CYP) to salt-sensitive hypertension with microarray data and bioinformatics analysis.

METHODS

Gene expression data set GSE4800 was downloaded from Gene Expression Omnibus database, including 6 gene chips from 3 Dahl salt sensitive (DS) rat samples and 3 Lewis (LEW) rat samples. Raw data were preprocessed and normalized, and then differentially expressed genes (DEGs) were identified with Limma package. Interaction network was constructed by employing STRING (Search Tool for the Retrieval of Interacting Genes) tool. GO (Gene Ontology) enrichment analysis was performed using FuncAssociate tool and pathway analysis was carried out by EASE (Expressing Analysis Systematic Explorer). BLAST (Basic Local Alignment Search Tool) was applied to explore the sequence homology among CYP3A genes in rat and human based on multiple alignments.

RESULTS

A total of 1264 DEGs, including 1082 up-regulated genes and 182 down-regulated genes were identified between DS and LEW samples. CYP3A2 and CYP3A9 were selected to construct the protein interaction network, which comprised 1653 pairs of interaction relationship among 100 genes. Functional analysis showed that CYP3A2 and CYP3A9 were most significantly related to oxidation reduction and metabolism of xenobiotics by cytochrome P450. Furthermore, the CYP3A2 and CYP3A9 genes in rats had high homology with genes CYP3A4and CYP3A5 in human beings.

CONCLUSIONS

CYP3A4 and CYP3A5 may contribute to salt-sensitive hypertension in human which may act as biomarkers for this disease.

A spike in parathyroid hormone during neck exploration may cause a false-negative intraoperative assay result

HYPOTHESIS

We hypothesize that false-negative results using the rapid intraoperative parathyroid hormone (IOPTH) assay can be caused by spikes in the level of parathyroid hormone that occur during mobilization of the adenoma.

DESIGN

Retrospective analysis of a case series.

SETTING

University tertiary care center.

PATIENTS

Ten consecutive patients with primary hyperparathyroidism.

INTERVENTIONS

All patients underwent neck exploration with IOPTH monitoring. Using a sampling protocol described in the literature, IOPTH values were checked at the time of incision, during mobilization of the adenoma, and 10 minutes after resection of the adenoma.

MAIN OUTCOME MEASURES

Patients were evaluated for adequate parathyroid tissue excision as determined by IOPTH levels and examination of ipsilateral glands. All patients had normal serum calcium values documented postoperatively. Parathyroid hormone half-life was calculated assuming first-order kinetic decay.

RESULTS

Nine patients had an appropriate decline in IOPTH with a mean +/- SD parathyroid hormone half-life of 3.9 +/- 1.08 minutes. Mobilization of the adenoma resulted in a spike in the IOPTH value, with 1 patient's value increasing from a baseline of 95.5 pg/mL (10.1 pmol/L) to 751 pg/mL (79.1 pmol/L). Another patient who was confirmed to have a solitary adenoma had a false-negative postexcision value. A spike in IOPTH that occurred during neck dissection was not detected by the sampling protocol and explains the false-negative value. A literature review revealed that most protocols check baseline values early in the operation and are at risk for false-negative results due to a spike from mobilization of the adenoma.

CONCLUSIONS

These data demonstrate that false-negative IOPTH assay findings can result from a spike in parathyroid hormone level during exploration, which may go unrecognized if baseline values are measured during the early stages of mobilization of the adenoma. We have altered our assay protocol and have begun measuring IOPTH at the time of neck incision, at the time the adenoma is completely removed (time zero [t(0)]), and 10 minutes after excision.

Unusual methyl-branched alpha,beta-unsaturated acyl chain substitutions in the Nod Factors of an arctic rhizobium, Mesorhizobium sp. strain N33 (Oxytropis arctobia)

Mesorhizobium sp. strain N33 (Oxytropis arctobia), a rhizobial strain isolated in arctic Canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera Astragalus, Onobrychis, and Oxytropis. Using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of N33 Nod factors, which are major determinants of nodulation. They are pentameric lipochito-oligosaccharides 6-O sulfated at the reducing end and exhibit other original substitutions: 6-O acetylation of the glucosamine residue next to the nonreducing terminal glucosamine and N acylation of the nonreducing terminal glucosamine by methyl-branched acyl chains of the iso series, some of which are alpha,beta unsaturated. These unusual substitutions may contribute to the peculiar host range of N33. Analysis of N33 whole-cell fatty acids indicated that synthesis of the methyl-branched fatty acids depended on the induction of bacteria by plant flavonoids, suggesting a specific role for these fatty acids in the signaling process between the plant and the bacteria. Synthesis of the methyl-branched alpha,beta-unsaturated fatty acids required a functional nodE gene.

Genomic structure of the promoters of the human estrogen receptor-alpha gene demonstrate changes in chromatin structure induced by AP2gamma

Expression of human estrogen receptor-alpha (ERalpha) involves the activity from several promoters that give rise to alternate untranslated 5' exons. However, the genomic locations of the alternate 5' exons have not been reported previously. We have developed a contig map of the human ERalpha gene that includes all of the known alternate 5' exons. By using S1 nuclease and 5'- rapid amplification of cDNA ends, the cap sites for the alternate ERalpha transcripts E and H were identified. DNase I-hypersensitive sites specific to ERalpha-positive cells were associated with each of the cap sites. A DNase I-hypersensitive site, HS1, was localized to binding sites for AP2 in the untranslated region of exon 1 and was invariably present in the chromatin structure of ERalpha-positive cells. Overexpression of AP2gamma in human mammary epithelial cells generated the HS1-hypersensitive site. The ERalpha promoter was induced by AP2gamma in mammary epithelial cells, and trans-activation was dependent upon the region of the promoter containing the HS1 site. These results demonstrate that AP2gamma trans-activates the ERalpha gene in hormone-responsive tumors by inducing changes in the chromatin structure of the ERalpha promoter. These data are further evidence for a critical role for AP2 in the oncogenesis of hormone-responsive breast cancers.

Distal emboli as an unusual late complication of a thrombosed arteriovenous hemodialysis graft

The creation of an arteriovenous fistula for long-term hemodialysis access is one of the most commonly performed procedures in vascular and transplantation surgery. Prosthetic conduits are frequently prone to failure within their first year of construction, and after one or two revisions, they are left in their thrombosed state as permanent subcutaneous foreign bodies in the extremities. Conventional teaching has regarded these chronically thrombosed grafts to have a benign natural history, and their removal has been considered unnecessary. We describe an unusual late complication of distal thromboemboli from a chronically occluded arteriovenous graft that was implanted 10 years before and appeared as acute hand ischemia.

[Bacterial genetic diversity in soils and their correlation with vegetation]

Soil is an important epicenter of biodiversity. Human activity has threatened such biodiversity through vegetation shift. As the major type of microbes, bacteria have played key roles in material cycling. Since simple morphological characters and the failure of the major portion of bacteria in surviving artificial cultivation have hindered bacterial diversity from analyses using traditional taxonomic approaches, bacterial diversity and its correlation with vegetation is less understood. In order to detour cultivation, tag serial sequencing strategy was developed in this study, in which a 26 base pair highly variable region has been chosen from 16S ribosomal RNA gene as variant-representing tags, ligated into serials and sequenced. Molecular bacterial diversity in soils has been determined using tag types, tag frequencies and diversity index as parameters. The correlation of bacterial diversity with vegetation has been explored as well. Bacterial diversity and differentiation correlate highly with contents of organic matter and nitrogen of soils and further vegetation.

The common nodulation genes of Astragalus sinicus rhizobia are conserved despite chromosomal diversity

The nodulation genes of Mesorhizobium sp. (Astragalus sinicus) strain 7653R were cloned by functional complementation of Sinorhizobium meliloti nod mutants. The common nod genes, nodD, nodA, and nodBC, were identified by heterologous hybridization and sequence analysis. The nodA gene was found to be separated from nodBC by approximately 22 kb and was divergently transcribed. The 2. 0-kb nodDBC region was amplified by PCR from 24 rhizobial strains nodulating A. sinicus, which represented different chromosomal genotypes and geographic origins. No polymorphism was found in the size of PCR products, suggesting that the separation of nodA from nodBC is a common feature of A. sinicus rhizobia. Sequence analysis of the PCR-amplified nodA gene indicated that seven strains representing different 16S and 23S ribosomal DNA genotypes had identical nodA sequences. These data indicate that, whereas microsymbionts of A. sinicus exhibit chromosomal diversity, their nodulation genes are conserved, supporting the hypothesis of horizontal transfer of nod genes among diverse recipient bacteria.

Nitric oxide, an important regulator of perfusion-contraction matching in conscious pigs

We examined whether nitric oxide (NO) inhibition during moderate reduction in coronary blood flow (CBF) would affect perfusion-contraction matching. Coronary stenosis (CS) was induced in conscious pigs, which resulted in a stable 39 +/- 1% reduction in CBF for 1.5 h. Ischemic zone wall thickening (IZWT) decreased by an average of 56 +/- 2% during CS from 2.7 +/- 0.2 mm. After reperfusion, myocardial stunning was observed, but this recovered without evidence of necrosis. After recovery and subsequent administration of systemic NO synthase inhibition (N(omega)-nitro-L-arginine, 25 mg. kg(-1). day(-1) x 3 days), CS for 1.5 h reduced CBF similarly but decreased IZWT significantly more, P < 0.05, by 89 +/- 5%. Myocardial stunning, i.e., the decrease in IZWT at 12 h post-CS, was more severe (-65 +/- 5% vs. -21 +/- 3%), P < 0.05. Furthermore, CS during NO synthase inhibition resulted in multifocal subendocardial areas of necrosis in the area at risk. These data suggest that in the intact, conscious pig, NO inhibition prevents perfusion-contraction matching, resulting in intensification of post-ischemic stunning and development of subendocardial necrosis.

Peripheral vascular endothelial dysfunction and apoptosis in old monkeys

To determine the effects of aging on vasoactivity in a primate model (Macaca fascicularis), 13 young male monkeys (aged 7.1+/-0.4 years) and 9 old male monkeys (aged 19.8+/-0.6 years) were chronically instrumented for measurement of left ventricular and aortic pressures and cardiac output. Total cholesterol, triglyceride, and fasting blood sugar levels were not different between the 2 groups. There were no significant differences in baseline mean aortic pressure and total peripheral resistance (TPR) in the young monkeys versus the old monkeys. TPR fell less (P<0.05) with acetylcholine (1 microg/kg) in old monkeys (-25+/-1%) than in young monkeys (-34+/-2%), whereas decreases in TPR with sodium nitroprusside were similar in old and young monkeys. There was no evidence of atherosclerosis, but apoptosis of endothelial cells was enhanced (P<0.05) in the aortas and femoral arteries, but not in the media, of the old monkeys. There was a relationship (r=0.62, P=0.013) between the incidence of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive endothelial cells and endothelial cell density in the femoral artery. The reduced endothelial cell density was also correlated (r=0.82, P<0.01) with depressed TPR responses to acetylcholine. Thus, vascular endothelial dysfunction was present in old monkeys without evidence of atherosclerosis, which may be due to endothelial apoptosis and reduced endothelial cell density.

Polycyclic aromatic hydrocarbons in the sediments of the South China Sea

Sixteen sediment samples, collected from the South China Sea, were analyzed for 11 parent polycyclic aromatic hydrocarbons (PAHs) using gas chromatography and gas chromatography-mass spectrometry. Total concentrations of the 11 PAHs studied in the sediments ranged from 24.7 to 275.4 ng/g with a mean of 145.9 ng/g dry sediment. PAH concentrations displayed a consistent distribution trend with the sediment organic carbon content. The linear regression analysis showed that the total concentration of PAHs in the sediment was significantly correlated to the sediment organic carbon content with a correlation coefficient of 0.735 (n=16). Special PAH compound ratios, such as phenanthrene/anthracene and fluoranthene/pyrene, were calculated to evaluate the relative importance of different origins. The collected data showed that pyrolytic input from anthropogenic combustion processes was predominant at almost all the stations investigated. Only one station, located in the proximity of oil wells, appeared to be contaminated predominantly by petrogenic input. Three anthropogenic PAHs, i.e. pyrene, benzo[a]pyrene and benzo[e]pyrene, exhibited similar distribution patterns in the studied area, implying that these compounds possess identical sources. However, perylene did not entirely follow the distribution trend of the three PAHs, suggesting that the sediment perylene probably derived from other sources such as in situ biogenic origins. Dibenzothiophene, a sulfur heterocyclic aromatic compound, was also measured in this study.

Determinants of the cardiomyopathic phenotype in chimeric mice overexpressing cardiac Gsalpha

Mice with overexpressed cardiac Gsalpha develop cardiomyopathy, characterized by myocyte hypertrophy and extensive myocardial fibrosis. The cardiomyopathy likely involves chronically enhanced beta-adrenergic signaling, because it can be blocked with long-term propranolol treatment. It remains unknown whether the genotype of the myocyte is solely responsible for the progressive pathological changes. A chimeric population in the heart should answer this question. Accordingly, we developed a chimeric animal, which combined cells from a transgenic overexpressed Gsalpha parent and a Rosa mouse containing the LacZ reporter gene, facilitating identification of the non-Gsalpha cells, which express a blue color with exposure to beta-galactosidase. We studied these animals at 14 to 17 months of age (when cardiomyopathy should have been present), with the proportion of Gsalpha cells in the myocardium ranging from 5% to 88%. beta-Galactosidase staining of the hearts demonstrated Gsalpha and Rosa cells, exhibiting a mosaic pattern. The fibrosis and hypertrophy, characteristic of the cardiomyopathy, were not distributed randomly. There was a direct correlation (r=0.85) between the extent of myocyte hypertrophy (determined by computer imaging) and the quantity of Gsalpha cells. The fibrosis, determined by picric acid Sirius red, was also more prominent in areas with the greatest Gsalpha cell density, with a correlation of r=0.88. Thus, the overexpressed Gsalpha can exert its action over the life of the animal, resulting in a local picture of cardiomyopathic damage in discrete regions of the heart, where clusters of the overexpressed Gsalpha cells reside, sparing the clusters of normal cells derived from the normal Rosa parent.

Identification of lumichrome as a sinorhizobium enhancer of alfalfa root respiration and shoot growth

Sinorhizobium meliloti bacteria produce a signal molecule that enhances root respiration in alfalfa (Medicago sativa L.) and also triggers a compensatory increase in whole-plant net carbon assimilation. Nuclear magnetic resonance, mass spectrometry, and ultraviolet-visible absorption identify the enhancer as lumichrome, a common breakdown product of riboflavin. Treating alfalfa roots with 3 nM lumichrome increased root respiration 21% (P < 0.05) within 48 h. A closely linked increase in net carbon assimilation by the shoot compensated for the enhanced root respiration. For example, applying 5 nM lumichrome to young alfalfa roots increased plant growth by 8% (P < 0.05) after 12 days. Soaking alfalfa seeds in 5 nM lumichrome before germination increased growth by 18% (P < 0.01) over the same period. In both cases, significant growth enhancement (P < 0.05) was evident only in the shoot. S. meliloti requires exogenous CO2 for growth and may benefit directly from the enhanced root respiration that is triggered by lumichrome. Thus Sinorhizobium-alfalfa associations, which ultimately form symbiotic N2-reducing root nodules, may be favored at an early developmental stage by lumichrome, a previously unrecognized mutualistic signal. The rapid degradation of riboflavin to lumichrome under many physiological conditions and the prevalence of riboflavin release by rhizosphere bacteria suggest that events demonstrated here in the S. meliloti-alfalfa association may be widely important across many plant-microbe interactions.

Structure of the Mesorhizobium huakuii and Rhizobium galegae Nod factors: a cluster of phylogenetically related legumes are nodulated by rhizobia producing Nod factors with alpha,beta-unsaturated N-acyl substitutions

Rhizobia are symbiotic bacteria that synthesize lipochitooligosaccharide Nod factors (NFs), which act as signal molecules in the nodulation of specific legume hosts. Based on the structure of their N-acyl chain, NFs can be classified into two categories: (i) those that are acylated with fatty acids from the general lipid metabolism; and (ii) those (= alphaU-NFs) that are acylated by specific alpha,beta-unsaturated fatty acids (containing carbonyl-conjugated unsaturation(s)). Previous work has described how rhizobia that nodulate legumes of the Trifolieae and Vicieae tribes produce alphaU-NFs. Here, we have studied the structure of NFs from two rhizobial species that nodulate important genera of the Galegeae tribe, related to Trifolieae and Vicieae. Three strains of Mesorhizobium huakuii, symbionts of Astragalus sinicus, produced as major NFs, pentameric lipochitooligosaccharides O-sulphated and partially N-glycolylated at the reducing end and N-acylated, at the non-reducing end, by a C18:4 fatty acid. Two strains of Rhizobium galegae, symbionts of Galega sp., produced as major NFs, tetrameric O-carbamoylated NFs that could be O-acetylated on the glucosamine residue next to the non-reducing terminal glucosamine and were N-acylated by C18 and C20 alpha,beta-unsaturated fatty acids. These results suggest that legumes nodulated by rhizobia synthesizing alphaU-NFs constitute a phylogenetic cluster in the Galegoid phylum.

Beta-adrenergic receptor blockade arrests myocyte damage and preserves cardiac function in the transgenic G(salpha) mouse

Transgenic (TG) mice with cardiac G(salpha) overexpression exhibit enhanced inotropic and chronotropic responses to sympathetic stimulation, but develop cardiomyopathy with age. We tested the hypothesis that cardiomyopathy in TG mice with G(salpha) overexpression could be averted with chronic beta-adrenergic receptor (beta-AR) blockade. TG mice and age-matched wild-type littermates were treated with the beta-AR blocker propranolol for 6-7 months, starting at a time when the cardiomyopathy was developing but was not yet severe enough to induce significant cardiac depression (9.5 months of age), and ending at a time when cardiac depression and cardiomyopathy would have been clearly manifest (16 months of age). Propranolol treatment, which can induce cardiac depression in the normal heart, actually prevented cardiac dilation and the depressed left ventricular function characteristic of older TG mice, and abolished premature mortality. Propranolol also prevented the increase in myocyte cross-sectional area and myocardial fibrosis. Myocyte apoptosis, already apparent in 9-month-old TG mice, was actually eliminated by chronic propranolol. This study indicates that chronic sympathetic stimulation over an extended period is deleterious and results in cardiomyopathy. Conversely, beta-AR blockade is salutary in this situation and can prevent the development of cardiomyopathy.

Combining SSH and cDNA microarrays for rapid identification of differentially expressed genes

Comparing patterns of gene expression in cell lines and tissues has important applications in a variety of biological systems. In this study we have examined whether the emerging technology of cDNA microarrays will allow a high throughput analysis of expression of cDNA clones generated by suppression subtractive hybridization (SSH). A set of cDNA clones including 332 SSH inserts amplified by PCR was arrayed using robotic printing. The cDNA arrays were hybridized with fluorescent labeled probes prepared from RNA from ER-positive (MCF7 and T47D) and ER-negative (MDA-MB-231 and HBL-100) breast cancer cell lines. Ten clones were identified that were over-expressed by at least a factor of five in the ER-positive cell lines. Northern blot analysis confirmed over-expression of these 10 cDNAs. Sequence analysis identified four of these clones as cytokeratin 19, GATA-3, CD24 and glutathione-S-transferase mu-3. Of the remaining six cDNA clones, four clones matched EST sequences from two different genes and two clones were novel sequences. Flow cytometry and immunofluorescence confirmed that CD24 protein was over-expressed in the ER-positive cell lines. We conclude that SSH and microarray technology can be successfully applied to identify differentially expressed genes. This approach allowed the identification of differentially expressed genes without the need to obtain previously cloned cDNAs.

Adsorption of Dibenzothiophene on Marine Sediments Treated by a Sequential Procedure

The sorption behavior of dibenzothiophene on marine sediments treated by a sequential procedure was investigated. Sorption isotherms for dibenzothiophene on both no treatment and NaOAc-HOAc treatment sediments were all linear. Differences in Kp's between no-treatment and NaOAc-HOAc treatment sediments were mainly the result of differences in organic carbon content. Nonlinear adsorption isotherms of dibenzothiophene were observed on the sediments treated with H2O2 and could be described by the Freundlich equation. Nonlinear isotherms suggested that the sorption mechanism was a heterogenous adsorption process occurring on the surfaces of the residual organic matter and the bare inorganic minerals in the sediment. A linear correlation was found between the Freundlich constant K and the residual organic carbon. In addition, the clay content in the sediment also had a significant effect on the residual organic carbon content and the Freundlich constant K. Differences in the isotherms of dibenzothiophene between the H2O2 treatment sediments and the no or NaOAc-HOAc treatment sediments indicated that the sorption was strongly influenced by the change in composition as well as by the percentage of organic matter in the sediments. Copyright 1997Academic Press

Cyr61 and Fisp12 are both ECM-associated signaling molecules: activities, metabolism, and localization during development

cyr61 and fisp12 are homologous immediate-early genes that are transcriptionally activated upon growth factor stimulation in fibroblasts. Their gene products belong to an emerging family of secreted proteins with a high degree of sequence homology, including conservation of all 38 cysteine residues in their secreted portions. We have recently shown that Cyr61 is an extracellular matrix (ECM) signaling molecule that promotes cell proliferation, migration, and adhesion. We describe herein the first purification of the Fisp12 protein and we compare the activities of purified Cyr61 and Fisp12, their metabolism, targeting, and their localization during development. Although Fisp12 is the mouse homolog of the human connective tissue growth factor (CTGF), it has no detectable mitogenic activity by itself. Rather, Fisp12 enhances fibroblast growth factor-induced DNA synthesis. The activities of Fisp12 and Cyr61 are nearly indistinguishable in three cell types tested: fibroblasts, endothelial, and epithelial cells. Both proteins are found in the ECM, although Cyr61 associates with the ECM more strongly and binds heparin with higher affinity. Fisp12, but not Cyr61, is also found in the culture medium, suggesting that Fisp12 might be able to act at a distance from its site of secretion, whereas Cyr61 might act more locally. Both secreted proteins are internalized and degraded through the lysosomal pathway, suggesting interaction with cell surface receptors. Both Cyr61 and Fisp12 are found in the placenta and the circulatory system as detected by immunohistochemistry, whereas Cyr61, but not Fisp12, is found in the skeletal and nervous systems. Fisp12, but not Cyr61, is found in secretory organs. Taken together, we propose that Cyr61 and Fisp12 are both signaling cell adhesion molecules that have similar or overlapping activities, and their differential sites of localization and targeting may dictate specificity in their biological roles.

Extraordinarily polymorphic ribosomal DNA in wild and cultivated rice

A collection of 481 rice accessions was surveyed for ribosomal DNA (rDNA) intergenic spacer length polymorphism to assess the extent of genetic diversity in Chinese and Asian rice germplasm. The materials included 83 accessions of common wild rice, Oryza rufipogon, 75 of which were from China; 348 entries of cultivated rice (Oryza sativa), representing almost all the rice growing areas in China; and 50 cultivars from South and East Asia. A total of 42 spacer length variants (SLVs) were detected. The size differences between adjacent SLVs in the series were very heterogeneous, ranging from ca. 21 to 311 bp. The 42 SLVs formed 80 different rDNA phenotypic combinations. Wild rice displayed a much greater number of rDNA SLVs than cultivated rice, while cultivated rice showed a larger number of rDNA phenotypes. Indica and japonica groups of O. sativa contained about equal numbers of SLVs, but the SLV distribution was significantly differentiated: indica rice was preferentially associated with longer SLVs and japonica rice with shorter ones. The results may have significant implications regarding the origin and evolution of cultivated rice, as well as the inheritance and molecular evolution of rDNA intergenic spacers in rice. Key words : rDNA, Oryza rufipogon, Oryza sativa, germplasm diversity, evolution.

Molecular marker heterozygosity and hybrid performance in indica and japonica rice

An essential assumption underlying markerbased prediction of hybrid performance is a strong linear correlation between molecular marker heterozygosity and hybrid performance or heterosis. This study was intended to investigate the extent of the correlations between molecular marker heterozygosity and hybrid performance in crosses involving two sets of rice materials, 9 indica and 11 japonica varieties. These materials represent a broad spectrum of the cultivated rice gene pool including landraces, primitive cultivars, historically important cultivars, modern elite cultivars and parents of superior hybrids. Varieties within each set were intermated in all possible nonreciprocal pairs resulting in 36 crosses in the indica set and 55 in the japonica set. The F1s and their parents, 111 entries in total, were examined for performance of seven traits in a replicated field trial. The parents were surveyed for polymorphisms using 96 RFLP and ten SSR markers selected at regular intervals from a published molecular marker linkage map. Molecular marker genotypes of the F1 hybrids were deduced from the parental genotypes. The analysis showed that, with very few exceptions, correlations in the indica dataset were higher than in that of their japonica counterparts. Among the seven traits analyzed, plant height showed the highest correlation between heterozygosity and hybrid performance and heteorsis in both indica and japonica datasets. Correlations were low to intermediate between hybrid performance and heterozygosity (both general and specific) in yield and yield component traits in both indica and japonica sets, and also low to intermediate between specific heterozygosity and heterosis in the indica set, whereas very little correlation was detected between heterosis and heterozygosity (either general or specific) in the japonica set. In comparison to the results from our previous studies, we concluded that the relationship between molecular marker heterozygosity and heterosis is variable, depending on the genetic materials used in the study, the diversity of rice germplasms and the complexity of the genetic basis of heterosis.

Analysis of the barley and rice genomes by comparative RFLP linkage mapping

Comparative genetic mapping of rice and barley, both major crop species with extensive genetic resources, offers the possibility of uniting two well-established and characterized genetic systems. In the present study, we screened 229 molecular markers and utilized 110 polymorphic orthologous loci to construct comparative maps of the rice and barley genomes. While extensive chromosomal rearrangements, including inversions and intrachromosomal translocations, differentiate the rice and barley genomes, several syntenous chromosomes are evident. Indeed, several chromosomes and chromosome arms appear to share nearly identical gene content and gene order. Seventeen regions of conserved organization were detected, spanning 287 cM (24%) and 321 cM (31%) of the rice and barley genomes, respectively. The results also indicate that most (72%) of the single-copy sequences in barley are also single copy in rice, suggesting that the large barley genome arose by unequal crossing over and amplification of repetitive DNA sequences and not by the duplication of single-copy sequences. Combining these results with those previously reported for comparative analyses of rice and wheat identified nine putatively syntenous chromosomes among barley, wheat and rice. The high degree of gene-order conservation as detected by comparative mapping has astonishing implications for interpreting genetic information among species and for elucidating chromosome evolution and speciation.

Cyr61, a product of a growth factor-inducible immediate-early gene, promotes cell proliferation, migration, and adhesion

cyr61 was first identified as a growth factor-inducible immediate-early gene in mouse fibroblasts. The encoded Cyr61 protein is a secreted, cystein-rich heparin-binding protein that associates with the cell surface and the extracellular matrix, and in these aspects it resembles the Wnt-1 protein and a number of known growth factors. During embryogenesis, cyr61 is expressed most notably in mesenchymal cells that are differentiating into chondrocytes and in the vessel walls of the developing circulatory system. cyr61 is a member of an emerging gene family that encodes growth regulators, including the connective tissue growth factor and an avian proto-oncoprotein, Nov cyr61 also shares sequence similarities with two Drosophila genes, twisted gastrulation and short gastrulation, which interact with decapentaplegic to regulate dorsal-ventral patterning. In this report we describe the purification of the Cyr61 protein in a biologically active form, and we show that purified Cyr61 has the following activities: (i) it promotes the attachment and spreading of endothelial cells in a manner similar to that of fibronectin; (ii) it enhances the effects of basic fibroblast growth factor and platelet-derived growth factor on the rate of DNA synthesis of fibroblasts and vascular endothelial cells, although it has no detectable mitogenic activity by itself; and (iii) it acts as a chemotactic factor for fibroblasts. Taken together, these activities indicate that Cyr61 is likely to function as an extracellular matrix signaling molecule rather than as a classical growth factor and may regulate processes of cell proliferation, migration, adhesion, and differentiation during development.

Comparative analysis of microsatellite DNA polymorphism in landraces and cultivars of rice

Genetic polymorphisms of ten microsatellite DNA loci were examined among 238 accessions of landraces and cultivars that represent a significant portion of the distribution range for both indica and japonica groups of cultivated rice. In all, 93 alleles were identified with these ten markers. The number of alleles varied from a low of 3 or 4 at each of four loci, to an intermediate value of 9-14 at five loci, and to an extraordinarily high 25 at one locus. The numbers of alleles per locus are much larger than those detected using other types of markers. The number of alleles detected at a locus is significantly correlated with the number of simple sequence repeats in the targeted microsatellite DNA. Indica rice has about 14% more alleles than japonica rice, and such allele number differences are more pronounced in landraces than in cultivars. The indica-japonica differentiation component accounted for about 10% of the diversity in the total sample, and twice as much differentiation was detected in cultivars as in landraces. About two-thirds as many alleles were observed in cultivars as in landraces; another two-thirds of the alleles in the cultivar group were found in modern elite cultivars or parents of hybrid rice. The majority of the simple sequence repeat (SSR) alleles that were present in high or intermediate frequencies in landraces ultimately survived into modern elite cultivars and hybrids. The greater resolving power and the efficient production of massive amounts of SSR data may be particularly useful for germplasm assessment and evolutionary studies of crop plants.

A comparative analysis of genetic polymorphism in wild and cultivated barley from Tibet using isozyme and ribosomal DNA markers

This study was conducted to address some of the issues concerning the possible significance of Tibet in the origin and evolution of cultivated barley. A total of 1757 barley accessions from Tibet, including 1496 entries of Hordeum vulgare ssp. vulgare (HV), 229 entries of the six-rowed wild barley H. vulgare ssp. agriocrithon (HA), and 32 entries of the two-rowed wild barley H. vulgare ssp. spontaneum (HS), were assayed for allozymes at four esterase loci. A subsample of 491 accessions was surveyed for spacer-length polymorphism at two ribosomal DNA loci. Genetic variation is extensive in these barley groups, and the amount of genetic diversity in cultivated barley of this region is comparable with that of cultivated barley worldwide. The level of genetic variation of HA is significantly lower than the other two barley groups, and there is also substantial heterogeneity in the level of polymorphism among different agrigeographical subregions. However, little genetic differentiation was detected among the three barley groups (HV, HA, and HS), as well as among different agrigeographical subregions. Comparison of the results from this and previous studies indicated a strong differentiation between Oriental and Occidental barley, thus favoring the hypothesis of a diphyletic origin of cultivated barley.Key words: Hordeum, allozyme, rDNA spacer-length variation, centre of diversity, phylogeny.

Extraordinarily polymorphic microsatellite DNA in barley: species diversity, chromosomal locations, and population dynamics

This study was undertaken to assess the extent of genetic variation in barley simple sequence repeats (SSRs) and to study the evolutionary dynamics of SSR alleles. SSR polymorphisms were resolved by the polymerase chain reaction with four pairs of primers. In total, 71 variants were observed in a sample of 207 accessions of wild and cultivated barley. Analyses of wheat-barley addition lines and barley doubled haploids identified these variants (alleles) with four loci, each located on a different chromosome. The numbers of alleles detected at a locus corresponded to the number of nucleotide repeats in the microsatellite sequences. The numbers of alleles at two loci were 28 and 37; to our knowledge these are the largest numbers of alleles for single Mendelian loci reported in plants. Three alleles were resolved by each of the other two loci. Allelic diversity was greater in wild than in cultivated barley and surveys of two generations (F8 and F53) of Composite Cross II, an experimental population of cultivated barley, showed that few of the alleles present in the 28 parents survived into generation F53, whereas some infrequent alleles reached high frequencies. Such changes in frequency indicate that the chromosomal segments marked by the SSR alleles are under the influence of natural selection. The SSR variants allow specific DNA sequences to be followed through generations. Thus, the great resolving power of SSR assays may provide clues regarding the precise targets of natural and man-directed selection.

Cyr61, product of a growth factor-inducible immediate early gene, is associated with the extracellular matrix and the cell surface

cyr61 is a specific target for activation by platelet-derived growth factor and fibroblast growth factor and is inducible by the oncogene v-src. It is a member of the class of immediate early genes that includes those encoding protooncogene products, transcription factors, and cytokines. We have previously characterized the synthesis and degradation of the cyr61-encoded mRNA and protein. Although the deduced Cyr61 protein sequence contains an NH2-terminal secretory signal, it is not detectable in the conditioned medium of serum-stimulated cells. We show here that in rapidly growing cell cultures, newly synthesized Cyr61 is secreted and is associated with both the extracellular matrix and the cell surface. In contrast, Cyr61 secreted in serum-stimulated quiescent cells is directed to the cell surface and is hot incorporated into the extracellular matrix. Once associated with the extracellular matrix, Cyr61 has a half-life of greater than 24 h, whereas intracellular and cell surface-associated Cyr61 has an apparent half-life of approximately 30 min. Furthermore, Cyr61 appears to bind heparin with high affinity. These observations suggest similarities among Cyr61, the fibroblast growth factors (heparin-binding growth factors), and the protooncogene product Int-1 and are consistent with the hypothesis that Cyr61 plays a role in cell-cell communication involving the interaction of neighboring cells.

Expression of cyr61, a growth factor-inducible immediate-early gene

A set of immediate-early genes that are rapidly activated by serum or purified platelet-derived growth factor in mouse 3T3 fibroblasts has been previously identified. Among these genes, several are related to known or putative transcription factors and growth factors, supporting the notion that some of these genes encode regulatory molecules important to cell growth. We show here that a member of this set of genes, cyr61 (originally identified by its cDNA 3CH61), encodes a 379-amino-acid polypeptide rich in cysteine residues. cyr61 can be induced through protein kinase C-dependent and -independent pathways. Unlike many immediate-early genes that are transiently expressed, the cyr61 mRNA is accumulated from the G0/G1 transition through mid-G1. This expression pattern is due to persistent transcription, while the mRNA is rapidly turned over during the G0/G1 transition and in mid-G1 at the same rate. In logarithmically growing cells, the cyr61 mRNA level is constant throughout the cell cycle. Cyr61 contains an N-terminal secretory signal sequence; however, it is not detected in the culture medium by immunoprecipitation. Cyr61 is synthesized maximally at 1 to 2 h after serum stimulation and has a short half-life within the cell.