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Sample records for rubber tree clones

  1. Capacitance Regression Modelling Analysis on Latex from Selected Rubber Tree Clones

    NASA Astrophysics Data System (ADS)

    Rosli, A. D.; Hashim, H.; Khairuzzaman, N. A.; Mohd Sampian, A. F.; Baharudin, R.; Abdullah, N. E.; Sulaiman, M. S.; Kamaru'zzaman, M.

    2015-11-01

    This paper investigates the capacitance regression modelling performance of latex for various rubber tree clones, namely clone 2002, 2008, 2014 and 3001. Conventionally, the rubber tree clones identification are based on observation towards tree features such as shape of leaf, trunk, branching habit and pattern of seeds texture. The former method requires expert persons and very time-consuming. Currently, there is no sensing device based on electrical properties that can be employed to measure different clones from latex samples. Hence, with a hypothesis that the dielectric constant of each clone varies, this paper discusses the development of a capacitance sensor via Capacitance Comparison Bridge (known as capacitance sensor) to measure an output voltage of different latex samples. The proposed sensor is initially tested with 30ml of latex sample prior to gradually addition of dilution water. The output voltage and capacitance obtained from the test are recorded and analyzed using Simple Linear Regression (SLR) model. This work outcome infers that latex clone of 2002 has produced the highest and reliable linear regression line with determination coefficient of 91.24%. In addition, the study also found that the capacitive elements in latex samples deteriorate if it is diluted with higher volume of water.

  2. Biocompatibility studies of natural rubber latex from different tree clones and collection methods.

    PubMed

    Floriano, Juliana Ferreira; da Mota, Lígia Souza Lima Silveira; Furtado, Edson Luiz; Rossetto, Victor José Vieira; Graeff, Carlos F O

    2014-02-01

    Natural rubber latex (NRL) has several features that make it an excellent biomaterial to promote the growth and repair of tissues, skin and bones. Most of the research with NRL membranes uses a mixture of different clones and chemical preservatives in the collection process. In this study, we compared five clones that produce NRL, seeking to identify their differences in biocompatibility. The clones studied were RRIM 600, PB 235, GT1, PR 255 and IAN 873 commonly found in plantations in Brazil. We did also study the effect of ammonia used during latex collection. NRL membranes were prepared aseptically and sterilized. In the in vitro tests, the membranes remained in direct contact with mouse fibroblasts cells for three periods, 24, 48 and 72 h. In the in vivo tests, the membranes were implanted subcutaneously in rabbits. The results indicated the biocompatibility of the membranes obtained from all clones. Membranes from the clones RRIM 600 and IAN 873 induced greater cell proliferation, suggesting greater bioactivity. It was found that the membranes made from latex that was in contact with ammonia during collection, showed cytotoxic and genotoxic effects in cultures, as well as necrosis, and increased inflammatory cells in the rabbit's tissues close to the implant.

  3. Comparative transcriptome analysis of latex from rubber tree clone CATAS8-79 and PR107 reveals new cues for the regulation of latex regeneration and duration of latex flow.

    PubMed

    Chao, Jinquan; Chen, Yueyi; Wu, Shaohua; Tian, Wei-Min

    2015-04-18

    Rubber tree (Hevea brasiliensis Muell. Arg.) is the primarily commercial source of natural rubber in the world. Latex regeneration and duration of latex flow after tapping are the two factors that determine rubber yield of rubber tree, and exhibit a huge variation between rubber tree clones CATAS8-79 and PR107. To dissect the molecular mechanism for the regulation of latex regeneration and duration of latex flow, we sequenced and comparatively analyzed latex of rubber tree clone CATAS8-79 and PR107 at transriptome level. More than 26 million clean reads were generated in each pool and 51,829 all-unigenes were totally assembled. A total of 6,726 unigenes with differential expression patterns were detected between CATAS8-79 and PR107. Functional analysis showed that genes related to mass of categories were differentially enriched between the two clones. Expression pattern of genes which were involved in latex regeneration and duration of latex flow upon successive tapping was analyzed by quantitative PCR. Several genes related to rubber biosynthesis, cellulose and lignin biosynthesis and rubber particle aggregation were differentially expressed between CATAS8-79 and PR107. This is the first report about probing latex regeneration and duration of latex flow by comparative transcriptome analysis. Among all the suggested factors, it is more important that the level of endogenous jasmonates, carbohydrate metabolism, hydroxymethylglutaryl-CoA reductase (HMGR) and Hevea rubber transferase (HRT) in mevalonate (MVA) parthway for latex regeneration while the level of endogenous ethylene (ETH), lignin content of laticifer cell wall, antioxidants and glucanases for the duration of latex flow. These data will provide new cues for understanding the molecular mechanism for the regulation of latex regeneration and duration of latex flow in rubber tree.

  4. Rubber Tree (Hevea brasiliensis Muell. Arg).

    PubMed

    Venkatachalam, Perumal; Jayashree, Radha; Rekha, Karumamkandathil; Sushmakumari, Sreedharannair; Sobha, Sankaren; Kumari Jayasree, Parukkuttyamma; Kala, Radha Gopikkuttanunithan; Thulaseedharan, Arjunan

    2006-01-01

    Rubber tree (Hevea brasiliensis Muell. Arg.) is an important industrial crop for natural rubber production. At present, more than 9.5 million hectares in about 40 countries are devoted to rubber tree cultivation with a production about 6.5 million tons of dry rubber each year. The world supply of natural rubber is barely keeping up with a global demand for 12 million tons of natural rubber in 2020. Tapping panel dryness (TPD) is a complex physiological syndrome widely found in rubber tree plantations, which causes severe yield and crop losses in natural rubber producing countries. Currently, there is no effective prevention or treatment for this serious malady. As it is a perennial tree crop, the integration of specific desired traits through conventional breeding is both time-consuming and labour-intensive. Genetic transformation with conventional breeding is certainly a more promising tool for incorporation of agronomically important genes that could improve existing Hevea genotype. This chapter provides an Agrobacterium-mediated transformation protocol for rubber tree using immature anther-derived calli as initial explants. We have applied this protocol to generate genetically engineered plants from a high yielding Indian clone RRII 105 of Hevea brasiliensis (Hb). Calli were co-cultured with Agrobacterium tumefaciens harboring a plasmid vector containing the Hb superoxide dismutase (SOD) gene and the reporter gene used was beta-glucuronidase (GUS) gene (uidA). The selectable marker gene used was neomycin phosphotransferase (nptII) and kanamycin was used as selection agent. We found that a suitable transformation protocol for Hevea consists of a 3-d co-cultivation with Agrobacterium in the presence of 20 mM acetosyringone, 15 mM betaine HCl, and 11.55 mM proline followed by selection on medium containing 300 mg/L kanamycin. Transformed calli surviving on medium containing 300 mg/L kanamycin showed a strong GUS-positive reaction. Upon subsequent subculture into

  5. Molecular cloning, expression profiles and characterization of a novel translationally controlled tumor protein in rubber tree (Hevea brasiliensis).

    PubMed

    Li, Dejun; Deng, Zhi; Liu, Xianghong; Qin, Bi

    2013-03-15

    The translationally controlled tumor protein (TCTP) is a multi-functioning protein that carries out vital roles in various life processes. In this study, a new TCTP gene, designated as HbTCTP1, was isolated in Hevea brasiliensis. The full-length complementary DNA (cDNA) of HbTCTP1 contained a maximum open reading frame (ORF) of 507base pair (bp) encoding 168 amino acids. The sequence comparison showed that the deduced HbTCTP1 indicated high identities to plant TCTP proteins, and clustered in the dicot cluster of plant TCTPs. Although HbTCTP1 and human TCTP proteins did not parallel in overall sequence similarity, they indicated highly similar 3D structures with a nearly identical spatial organization of α-helices, β-sheets, and coil regions. Real time reverse-transcription PCR (RT-PCR) analyses showed that HbTCTP1 was expressed throughout different tissues and developmental stages of leaves. Besides being related to tapping panel dryness (TPD), the HbTCTP1 transcripts were regulated by various treatments, including drought, low temperature, high salt, ethrel (ET), wounding, H2O2, and methyl jasmonate (Me-JA) treatments. The recombinant HbTCTP1 fusion protein was shown to protect supercoiled plasmid DNA from damages induced by metal-catalyzed generation of reactive oxygen species. The (45)Ca(2+)-overlay assay showed that HbTCTP1 was a calcium-binding protein. Our results are greatly helpful in understanding the molecular characterization and expression profiles of HbTCTP1, and lay the foundation for further analyzing the function of HbTCTP1 in rubber tree. Copyright © 2012 Elsevier GmbH. All rights reserved.

  6. THERMOOXIDATIVE STUDY OF RAW NATURAL RUBBER FROM BRAZILIAN IAC 300 SERIES CLONES

    USDA-ARS?s Scientific Manuscript database

    The improvement of rubber tree species is of key importance due to the worldwide market demand of this renewable material essential for several types of industries. The thermal performance of natural rubber produced from new clones of IAC 300 series, and the Malaysian RRIM 600 clone (used as control...

  7. Genomic validation of PB 260 clone of rubber (Hevea brasiliensis) at Cikumpay Plantation by SSR marker

    NASA Astrophysics Data System (ADS)

    Royani, J. I.; Safarrida, A.; Rachmawati, I.; Khairiyah, H.; Mustika, I. P.; Suyono, A.; Rudiyana, Y.; Kubil; Nurjaya; Arianto, A.

    2017-05-01

    Rubber from Hevea brasiliensis is the only commercial natural rubber in the world. Propagation of rubber trees usually done by grafting and seed germination. BPPT had been producing rubber tree by in vitro technique with embryo somatic methods. Validation of mother plant for in vitro propagation is important to compare between mother plant and propagated plants. The aim for this research was to validation of PB 260 clone that planted at Cikumpay Plantation by SSR marker. Sampling of 10 rubber leaves were done at Cikumpay Plantation based on GPS position from the area of PB 260 clone. Rubber leaves were isolated with CTAB modification method to obtained DNA. Four of SSR primers from rubber, i.e.: hmac 4, hmac 5, hmct 1, and hmct 5, were used as primers to amplification of rubber DNA. The result showed that no band that different from 10 rubber of PB 260 clone at Cikumpay Plantation. This research will continue to compare genomic validation between mother plant and propagated plants that had been produced from BPPT.

  8. Statistical Discrimination of Latex between Healthy and White Root Infected Rubber Tree based on Dry Rubber Content

    NASA Astrophysics Data System (ADS)

    Suhaimi Sulaiman, Mohd; Hashim, Hadzli; Faiz Mohd Sampian, Ahmad; Korlina Madzhi, Nina; Faris Mohd Azmi, Azrie; Aishah Khairuzzaman, Noor; Aima Ismail, Faridatul

    2015-11-01

    Dry rubber content (DRC) is one of main material existing inside latex. It is usually in ranged of 25% - 45% of rubber latex. Statistical analysis are done to determine the discrimination of dry rubber content of latex between healthy and white root infected rubber tree. Based on 150 rubber trees and 10 clones tested, parametric test which include normality test, error-bar plot, and paired samples test are done. The result outcomes have shown that both data of dry rubber content of latex for healthy and white root infected rubber tree are normally distributed. Error-bar plot test is clearly indicated that there is visible discrimination between both cases. Paired samples test are done to reinforce this findings in terms of numerical p- value which is found to be less than 0.05. Thus, this indicate overwhelming evidence that healthy group can be discriminated from white root. Conclusively, changes in DRC content in latex can be correlated with white root disease infections of rubber tree.

  9. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis

    PubMed Central

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D.; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami

    2016-01-01

    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis’s capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree. PMID:27339202

  10. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis.

    PubMed

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami

    2016-06-24

    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis's capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree.

  11. Molecular Cloning of HbPR-1 Gene from Rubber Tree, Expression of HbPR-1 Gene in Nicotiana benthamiana and Its Inhibition of Phytophthora palmivora

    PubMed Central

    Khunjan, Uraiwan; Ekchaweng, Kitiya; Panrat, Tanate; Tian, Miaoying; Churngchow, Nunta

    2016-01-01

    This is the first report to present a full-length cDNA (designated HbPR-1) encoding a putative basic HbPR-1 protein from rubber tree (Hevea brasiliensis) treated with salicylic acid. It was characterized and also expressed in Nicotiana benthamiana using Agrobacterium-mediated transient gene expression system in order to investigate the role of HbPR-1 gene in rubber tree against its oomycete pathogen Phytopthora palmivora and to produce recombinant HbPR-1 protein for microbial inhibition test. The HbPR-1 cDNA was 647 bp long and contained an open reading frame of 492 nucleotides encoding 163 amino acid residues with a predicted molecular mass of 17,681 Da and an isoelectric point (pI) of 8.56, demonstrating that HbPR-1 protein belongs to the basic PR-1 type. The predicted 3D structure of HbPR-1 was composed of four α-helices, three β-sheets, seven strands, and one junction loop. Expression and purification of recombinant HbPR-1 protein were successful using Agrobacterium-mediated transient expression and one-step of affinity chromatography. Heterologous expression of HbPR-1 in N. benthamiana reduced necrosis areas which were inoculated with P. palmivora zoospores, indicating that the expressed HbPR-1 protein played an important role in plant resistance to pathogens. The purified recombinant HbPR-1 protein was found to inhibit 64% of P. palmivora zoospore germination on a water agar plate compared with control, suggesting that it was an antimicrobial protein against P. palmivora. PMID:27337148

  12. Molecular Cloning of HbPR-1 Gene from Rubber Tree, Expression of HbPR-1 Gene in Nicotiana benthamiana and Its Inhibition of Phytophthora palmivora.

    PubMed

    Khunjan, Uraiwan; Ekchaweng, Kitiya; Panrat, Tanate; Tian, Miaoying; Churngchow, Nunta

    2016-01-01

    This is the first report to present a full-length cDNA (designated HbPR-1) encoding a putative basic HbPR-1 protein from rubber tree (Hevea brasiliensis) treated with salicylic acid. It was characterized and also expressed in Nicotiana benthamiana using Agrobacterium-mediated transient gene expression system in order to investigate the role of HbPR-1 gene in rubber tree against its oomycete pathogen Phytopthora palmivora and to produce recombinant HbPR-1 protein for microbial inhibition test. The HbPR-1 cDNA was 647 bp long and contained an open reading frame of 492 nucleotides encoding 163 amino acid residues with a predicted molecular mass of 17,681 Da and an isoelectric point (pI) of 8.56, demonstrating that HbPR-1 protein belongs to the basic PR-1 type. The predicted 3D structure of HbPR-1 was composed of four α-helices, three β-sheets, seven strands, and one junction loop. Expression and purification of recombinant HbPR-1 protein were successful using Agrobacterium-mediated transient expression and one-step of affinity chromatography. Heterologous expression of HbPR-1 in N. benthamiana reduced necrosis areas which were inoculated with P. palmivora zoospores, indicating that the expressed HbPR-1 protein played an important role in plant resistance to pathogens. The purified recombinant HbPR-1 protein was found to inhibit 64% of P. palmivora zoospore germination on a water agar plate compared with control, suggesting that it was an antimicrobial protein against P. palmivora.

  13. Identification of natural rubber and characterization of rubber biosynthetic activity in fig tree.

    PubMed

    Kang, H; Kang, M Y; Han, K H

    2000-07-01

    Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and (13)C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent K(m) values of 2.8 and 228 microM, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg(2+) ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree.

  14. Identification of Natural Rubber and Characterization of Rubber Biosynthetic Activity in Fig Tree1

    PubMed Central

    Kang, Hunseung; Kang, Min Young; Han, Kyung-Hwan

    2000-01-01

    Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and 13C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent Km values of 2.8 and 228 μm, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg2+ ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree. PMID:10889262

  15. Genome-wide analysis of microRNAs in rubber tree (Hevea brasiliensis L.) using high-throughput sequencing.

    PubMed

    Lertpanyasampatha, Manassawe; Gao, Lei; Kongsawadworakul, Panida; Viboonjun, Unchera; Chrestin, Hervé; Liu, Renyi; Chen, Xuemei; Narangajavana, Jarunya

    2012-08-01

    MicroRNAs (miRNAs) are short RNAs with essential roles in gene regulation in various organisms including higher plants. In contrast to the vast information on miRNAs from many economically important plants, almost nothing has been reported on the identification or analysis of miRNAs from rubber tree (Hevea brasiliensis L.), the most important natural rubber-producing crop. To identify miRNAs and their target genes in rubber tree, high-throughput sequencing combined with a computational approach was performed. Four small RNA libraries were constructed for deep sequencing from mature and young leaves of two rubber tree clones, PB 260 and PB 217, which provide high and low latex yield, respectively. 115 miRNAs belonging to 56 known miRNA families were identified, and northern hybridization validated miRNA expression and revealed developmental stage-dependent and clone-specific expression for some miRNAs. We took advantage of the newly released rubber tree genome assembly and predicted 20 novel miRNAs. Further, computational analysis uncovered potential targets of the known and novel miRNAs. Predicted target genes included not only transcription factors but also genes involved in various biological processes including stress responses, primary and secondary metabolism, and signal transduction. In particular, genes with roles in rubber biosynthesis are predicted targets of miRNAs. This study provides a basic catalog of miRNAs and their targets in rubber tree to facilitate future improvement and exploitation of rubber tree.

  16. Comparative proteome analysis of rubber latex serum from pathogenic fungi tolerant and susceptible rubber tree (Hevea brasiliensis).

    PubMed

    Havanapan, Phattara-Orn; Bourchookarn, Apichai; Ketterman, Albert J; Krittanai, Chartchai

    2016-01-10

    Many cultivated rubber trees (Hevea brasiliensis) are invaded by various Phytophthora species fungi, especially in tropical regions which result in crop yield losses. Comparative proteome analysis coupled with liquid chromatography electrospray/ionization (LC-ESI) mass spectrometry identification was employed to investigate the relative abundance of defense related proteins in Phytophthora sp. susceptible (RRIM600) and tolerant (BPM24) clones of rubber tree. Proteome maps of non-rubber constituent of these two model clones show similar protein counts, although some proteins show significant alterations in their abundance. Most of the differentially abundant proteins found in the serum of BPM24 illustrate the accumulation of defense related proteins that participate in plant defense mechanisms such as beta-1,3-glucanase, chitinase, and lectin. SDS-PAGE and 2-D Western blot analysis showed greater level of accumulation of beta-1,3-glucanase and chitinase in latex serum of BPM24 when compared to RRIM600. A functional study of these two enzymes showed that BPM24 serum had greater beta-1,3-glucanase and chitinase activities than that of RRIM600. These up-regulated proteins are constitutively expressed and would serve to protect the rubber tree BPM24 from any fungal invader. The information obtained from this work is valuable for understanding of defense mechanisms and plantation improvement of H. brasiliensis. Non-rubber constituents (latex serum) have almost no value and are treated as waste in the rubber agricultural industry. However, the serum of natural rubber latex contains biochemical substances. The comparative proteomics analysis of latex serum between tolerant and susceptible clones reveals that the tolerant BPM24 clone contained a high abundance of several classes of fungal pathogen-responsive proteins, such as glucanase and chitinase. Moreover, other proteins identified highlighted the accumulation of defensive-associated proteins participating in plant

  17. Tissue-Culture Method of Cloning Rubber Plants

    NASA Technical Reports Server (NTRS)

    Ball, E. A.

    1983-01-01

    Guayule plant, a high-yield rubber plant cloned by tissue-culture method to produce multiple new plants that mature quickly. By adjusting culture medium, excised shoot tip produces up to 50 identical guayule plants. Varying concentration of cytokinin, single excised tip produces either 1 or several (up to 50) new plants.

  18. Comparative Transcriptome Analysis of Latex Reveals Molecular Mechanisms Underlying Increased Rubber Yield in Hevea brasiliensis Self-Rooting Juvenile Clones

    PubMed Central

    Li, Hui-Liang; Guo, Dong; Zhu, Jia-Hong; Wang, Ying; Chen, Xiong-Ting; Peng, Shi-Qing

    2016-01-01

    Rubber tree (Hevea brasiliensis) self-rooting juvenile clones (JCs) are promising planting materials for rubber production. In a comparative trial between self-rooting JCs and donor clones (DCs), self-rooting JCs exhibited better performance in rubber yield. To study the molecular mechanism associated with higher rubber yield in self-rooting JCs, we sequenced and comparatively analyzed the latex of rubber tree self-rooting JCs and DCs at the transcriptome level. Total raw reads of 34,632,012 and 35,913,020 bp were obtained from the library of self-rooting JCs and DCs, respectively, by using Illumina HiSeq 2000 sequencing technology. De novo assemblies yielded 54689 unigenes from the library of self-rooting JCs and DCs. Among 54689 genes, 1716 genes were identified as differentially expressed between self-rooting JCs and DCs via comparative transcript profiling. Functional analysis showed that the genes related to the mass of categories were differentially enriched between the two clones. Several genes involved in carbohydrate metabolism, hormone metabolism and reactive oxygen species scavenging were up-regulated in self-rooting JCs, suggesting that the self-rooting JCs provide sufficient molecular basis for the increased rubber yielding, especially in the aspects of improved latex metabolisms and latex flow. Some genes encoding epigenetic modification enzymes were also differentially expressed between self-rooting JCs and DCs. Epigenetic modifications may lead to gene differential expression between self-rooting JCs and DCs. These data will provide new cues to understand the molecular mechanism underlying the improved rubber yield of H. brasiliensis self-rooting clones. PMID:27555864

  19. Analysis of Differentially Expressed Genes Associated with Coronatine-Induced Laticifer Differentiation in the Rubber Tree by Subtractive Hybridization Suppression.

    PubMed

    Zhang, Shi-Xin; Wu, Shao-Hua; Chen, Yue-Yi; Tian, Wei-Min

    2015-01-01

    The secondary laticifer in the secondary phloem is differentiated from the vascular cambia of the rubber tree (Hevea brasiliensis Muell. Arg.). The number of secondary laticifers is closely related to the rubber yield potential of Hevea. Pharmacological data show that jasmonic acid and its precursor linolenic acid are effective in inducing secondary laticifer differentiation in epicormic shoots of the rubber tree. In the present study, an experimental system of coronatine-induced laticifer differentiation was developed to perform SSH identification of genes with differential expression. A total of 528 positive clones were obtained by blue-white screening, of which 248 clones came from the forward SSH library while 280 clones came from the reverse SSH library. Approximately 215 of the 248 clones and 171 of the 280 clones contained cDNA inserts by colony PCR screening. A total of 286 of the 386 ESTs were detected to be differentially expressed by reverse northern blot and sequenced. Approximately 147 unigenes with an average length of 497 bp from the forward and 109 unigenes with an average length of 514 bp from the reverse SSH libraries were assembled and annotated. The unigenes were associated with the stress/defense response, plant hormone signal transduction and structure development. It is suggested that Ca2+ signal transduction and redox seem to be involved in differentiation, while PGA and EIF are associated with the division of cambium initials for COR-induced secondary laticifer differentiation in the rubber tree.

  20. Analysis of Differentially Expressed Genes Associated with Coronatine-Induced Laticifer Differentiation in the Rubber Tree by Subtractive Hybridization Suppression

    PubMed Central

    Zhang, Shi-Xin; Wu, Shao-Hua; Chen, Yue-Yi; Tian, Wei-Min

    2015-01-01

    The secondary laticifer in the secondary phloem is differentiated from the vascular cambia of the rubber tree (Hevea brasiliensis Muell. Arg.). The number of secondary laticifers is closely related to the rubber yield potential of Hevea. Pharmacological data show that jasmonic acid and its precursor linolenic acid are effective in inducing secondary laticifer differentiation in epicormic shoots of the rubber tree. In the present study, an experimental system of coronatine-induced laticifer differentiation was developed to perform SSH identification of genes with differential expression. A total of 528 positive clones were obtained by blue-white screening, of which 248 clones came from the forward SSH library while 280 clones came from the reverse SSH library. Approximately 215 of the 248 clones and 171 of the 280 clones contained cDNA inserts by colony PCR screening. A total of 286 of the 386 ESTs were detected to be differentially expressed by reverse northern blot and sequenced. Approximately 147 unigenes with an average length of 497 bp from the forward and 109 unigenes with an average length of 514 bp from the reverse SSH libraries were assembled and annotated. The unigenes were associated with the stress/defense response, plant hormone signal transduction and structure development. It is suggested that Ca2+ signal transduction and redox seem to be involved in differentiation, while PGA and EIF are associated with the division of cambium initials for COR-induced secondary laticifer differentiation in the rubber tree. PMID:26147807

  1. Draft genome sequence of the rubber tree Hevea brasiliensis

    PubMed Central

    2013-01-01

    Background Hevea brasiliensis, a member of the Euphorbiaceae family, is the major commercial source of natural rubber (NR). NR is a latex polymer with high elasticity, flexibility, and resilience that has played a critical role in the world economy since 1876. Results Here, we report the draft genome sequence of H. brasiliensis. The assembly spans ~1.1 Gb of the estimated 2.15 Gb haploid genome. Overall, ~78% of the genome was identified as repetitive DNA. Gene prediction shows 68,955 gene models, of which 12.7% are unique to Hevea. Most of the key genes associated with rubber biosynthesis, rubberwood formation, disease resistance, and allergenicity have been identified. Conclusions The knowledge gained from this genome sequence will aid in the future development of high-yielding clones to keep up with the ever increasing need for natural rubber. PMID:23375136

  2. Physiological and Molecular Responses to Variation of Light Intensity in Rubber Tree (Hevea brasiliensis Muell. Arg.)

    PubMed Central

    Wang, Li-feng

    2014-01-01

    Light is one of most important factors to plants because it is necessary for photosynthesis. In this study, physiological and gene expression analyses under different light intensities were performed in the seedlings of rubber tree (Hevea brasiliensis) clone GT1. When light intensity increased from 20 to 1000 µmol m−2 s−1, there was no effect on the maximal quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), indicating that high light intensity did not damage the structure and function of PSII reaction center. However, the effective photochemical quantum yield of PSII (Y(II)), photochemical quenching coefficient (qP), electron transfer rate (ETR), and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae (qL) were increased significantly as the light intensity increased, reached a maximum at 200 µmol m−2 s−1, but decreased from 400 µmol m−2 s−1. These results suggested that the PSII photochemistry showed an optimum performance at 200 µmol m−2 s−1 light intensity. The chlorophyll content was increased along with the increase of light intensity when it was no more than 400 µmol m−2 s−1. Since increasing light intensity caused significant increase in H2O2 content and decreases in the per unit activity of antioxidant enzymes SOD and POD, but the malondialdehyde (MDA) content was preserved at a low level even under high light intensity of 1000 µmol m−2 s−1, suggesting that high light irradiation did not induce membrane lipid peroxidation in rubber tree. Moreover, expressions of antioxidant-related genes were significantly up-regulated with the increase of light intensity. They reached the maximum expression at 400 µmol m−2 s−1, but decreased at 1000 µmol m−2 s−1. In conclusion, rubber tree could endure strong light irradiation via a specific mechanism. Adaptation to high light intensity is a complex process by regulating antioxidant enzymes activities, chloroplast formation, and

  3. Physiological and molecular responses to variation of light intensity in rubber Tree (Hevea brasiliensis Muell. Arg.).

    PubMed

    Wang, Li-feng

    2014-01-01

    Light is one of most important factors to plants because it is necessary for photosynthesis. In this study, physiological and gene expression analyses under different light intensities were performed in the seedlings of rubber tree (Hevea brasiliensis) clone GT1. When light intensity increased from 20 to 1000 µmol m(-2) s(-1), there was no effect on the maximal quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), indicating that high light intensity did not damage the structure and function of PSII reaction center. However, the effective photochemical quantum yield of PSII (Y(II)), photochemical quenching coefficient (qP), electron transfer rate (ETR), and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae (qL) were increased significantly as the light intensity increased, reached a maximum at 200 µmol m(-2) s(-1), but decreased from 400 µmol m(-2) s(-1). These results suggested that the PSII photochemistry showed an optimum performance at 200 µmol m(-2) s(-1) light intensity. The chlorophyll content was increased along with the increase of light intensity when it was no more than 400 µmol m(-2) s(-1). Since increasing light intensity caused significant increase in H2O2 content and decreases in the per unit activity of antioxidant enzymes SOD and POD, but the malondialdehyde (MDA) content was preserved at a low level even under high light intensity of 1000 µmol m(-2) s(-1), suggesting that high light irradiation did not induce membrane lipid peroxidation in rubber tree. Moreover, expressions of antioxidant-related genes were significantly up-regulated with the increase of light intensity. They reached the maximum expression at 400 µmol m(-2) s(-1), but decreased at 1000 µmol m(-2) s(-1). In conclusion, rubber tree could endure strong light irradiation via a specific mechanism. Adaptation to high light intensity is a complex process by regulating antioxidant enzymes activities, chloroplast formation, and

  4. Extraction of high-quality RNA from rubber tree leaves.

    PubMed

    Deng, Liu-Hong; Luo, Ming-Wu; Zhang, Chun-Fa; Zeng, Hui-Cai

    2012-01-01

    A specific technique capable of producing high-quality RNA for rapid amplification of cDNA ends (RACE) was established for challenging tissues: leaves of the rubber tree. Total RNA was extracted by cetyltrimethylammonium bromide (CTAB)-LiCl combined with TRIzol reagent. The isolated RNA was highly intact. With RNA as template, full-length cDNA was obtained (NCBI, AY461413) by RACE.

  5. Genetic Determinism of Sensitivity to Corynespora cassiicola Exudates in Rubber Tree (Hevea brasiliensis)

    PubMed Central

    Tran, Dinh Minh; Clément-Demange, André; Déon, Marine; Garcia, Dominique; Le Guen, Vincent; Clément-Vidal, Anne; Soumahoro, Mouman; Masson, Aurélien; Label, Philippe; Le, Mau Tuy; Pujade-Renaud, Valérie

    2016-01-01

    An indirect phenotyping method was developed in order to estimate the susceptibility of rubber tree clonal varieties to Corynespora Leaf Fall (CLF) disease caused by the ascomycete Corynespora cassiicola. This method consists in quantifying the impact of fungal exudates on detached leaves by measuring the induced electrolyte leakage (EL%). The tested exudates were either crude culture filtrates from diverse C. cassiicola isolates or the purified cassiicolin (Cas1), a small secreted effector protein produced by the aggressive isolate CCP. The test was found to be quantitative, with the EL% response proportional to toxin concentration. For eight clones tested with two aggressive isolates, the EL% response to the filtrates positively correlated to the response induced by conidial inoculation. The toxicity test applied to 18 clones using 13 toxinic treatments evidenced an important variability among clones and treatments, with a significant additional clone x treatment interaction effect. A genetic linkage map was built using 306 microsatellite markers, from the F1 population of the PB260 x RRIM600 family. Phenotyping of the population for sensitivity to the purified Cas1 effector and to culture filtrates from seven C. cassiicola isolates revealed a polygenic determinism, with six QTL detected on five chromosomes and percentages of explained phenotypic variance varying from 11 to 17%. Two common QTL were identified for the CCP filtrate and the purified cassiicolin, suggesting that Cas1 may be the main effector of CCP filtrate toxicity. The CCP filtrate clearly contrasted with all other filtrates. The toxicity test based on Electrolyte Leakage Measurement offers the opportunity to assess the sensitivity of rubber genotypes to C. cassiicola exudates or purified effectors for genetic investigations and early selection, without risk of spreading the fungus in plantations. However, the power of this test for predicting field susceptibility of rubber clones to CLF will have

  6. Genetic Determinism of Sensitivity to Corynespora cassiicola Exudates in Rubber Tree (Hevea brasiliensis).

    PubMed

    Tran, Dinh Minh; Clément-Demange, André; Déon, Marine; Garcia, Dominique; Le Guen, Vincent; Clément-Vidal, Anne; Soumahoro, Mouman; Masson, Aurélien; Label, Philippe; Le, Mau Tuy; Pujade-Renaud, Valérie

    2016-01-01

    An indirect phenotyping method was developed in order to estimate the susceptibility of rubber tree clonal varieties to Corynespora Leaf Fall (CLF) disease caused by the ascomycete Corynespora cassiicola. This method consists in quantifying the impact of fungal exudates on detached leaves by measuring the induced electrolyte leakage (EL%). The tested exudates were either crude culture filtrates from diverse C. cassiicola isolates or the purified cassiicolin (Cas1), a small secreted effector protein produced by the aggressive isolate CCP. The test was found to be quantitative, with the EL% response proportional to toxin concentration. For eight clones tested with two aggressive isolates, the EL% response to the filtrates positively correlated to the response induced by conidial inoculation. The toxicity test applied to 18 clones using 13 toxinic treatments evidenced an important variability among clones and treatments, with a significant additional clone x treatment interaction effect. A genetic linkage map was built using 306 microsatellite markers, from the F1 population of the PB260 x RRIM600 family. Phenotyping of the population for sensitivity to the purified Cas1 effector and to culture filtrates from seven C. cassiicola isolates revealed a polygenic determinism, with six QTL detected on five chromosomes and percentages of explained phenotypic variance varying from 11 to 17%. Two common QTL were identified for the CCP filtrate and the purified cassiicolin, suggesting that Cas1 may be the main effector of CCP filtrate toxicity. The CCP filtrate clearly contrasted with all other filtrates. The toxicity test based on Electrolyte Leakage Measurement offers the opportunity to assess the sensitivity of rubber genotypes to C. cassiicola exudates or purified effectors for genetic investigations and early selection, without risk of spreading the fungus in plantations. However, the power of this test for predicting field susceptibility of rubber clones to CLF will have

  7. Characterization of rubber tree microRNA in phytohormone response using large genomic DNA libraries, promoter sequence and gene expression analysis.

    PubMed

    Kanjanawattanawong, Supanath; Tangphatsornruang, Sithichoke; Triwitayakorn, Kanokporn; Ruang-areerate, Panthita; Sangsrakru, Duangjai; Poopear, Supannee; Somyong, Suthasinee; Narangajavana, Jarunya

    2014-10-01

    The para rubber tree is the most widely cultivated tree species for producing natural rubber (NR) latex. Unfortunately, rubber tree characteristics such as a long life cycle, heterozygous genetic backgrounds, and poorly understood genetic profiles are the obstacles to breeding new rubber tree varieties, such as those with improved NR yields. Recent evidence has revealed the potential importance of controlling microRNA (miRNA) decay in some aspects of NR regulation. To gain a better understanding of miRNAs and their relationship with rubber tree gene regulation networks, large genomic DNA insert-containing libraries were generated to complement the incomplete draft genome sequence and applied as a new powerful tool to predict a function of interested genes. Bacterial artificial chromosome and fosmid libraries, containing a total of 120,576 clones with an average insert size of 43.35 kb, provided approximately 2.42 haploid genome equivalents of coverage based on the estimated 2.15 gb rubber tree genome. Based on these library sequences, the precursors of 1 member of rubber tree-specific miRNAs and 12 members of conserved miRNAs were successfully identified. A panel of miRNAs was characterized for phytohormone response by precisely identifying phytohormone-responsive motifs in their promoter sequences. Furthermore, the quantitative real-time PCR on ethylene stimulation of rubber trees was performed to demonstrate that the miR2118, miR159, miR164 and miR166 are responsive to ethylene, thus confirmed the prediction by genomic DNA analysis. The cis-regulatory elements identified in the promoter regions of these miRNA genes help augment our understanding of miRNA gene regulation and provide a foundation for further investigation of the regulation of rubber tree miRNAs.

  8. Expression Profiles, Characterization and Function of HbTCTP in Rubber Tree (Hevea brasiliensis)

    PubMed Central

    Deng, Zhi; Chen, Jiangshu; Leclercq, Julie; Zhou, Zhuangzhi; Liu, Changren; Liu, Hui; Yang, Hong; Montoro, Pascal; Xia, Zhihui; Li, Dejun

    2016-01-01

    As a highly conserved protein, the translationally controlled tumor protein (TCTP) carries out vital roles in various life processes. In rubber tree, two TCTP genes, HbTCTP and HbTCTP1, were cloned, but only HbTCTP1 was studied in details. In this study, cis-acting regulatory elements, expression patterns, subcellular localization, interacting proteins, and antioxidant activity of HbTCTP were systematically analyzed. Besides the common cis-acting regulatory elements, HbTCTP promoter also harbored various known cis-elements that respond to hormone/stresses. Being consistent with the aforementioned results, HbTCTP was regulated by drought, low temperature, high salt, ethylene (ET), wounding, H2O2, and methyl jasmonate (MeJA) treatments. HbTCTP was expressed throughout different tissues and developmental stages of leaves. In addition, HbTCTP was associated with tapping panel dryness (TPD). HbTCTP was localized in the membrane, cytoplasm and the nucleus, and interacted with four proteins rubber elongation factor (REF), 17.5 kDa heat shock family protein, annexin, and REF-like stress related protein 1. Being similar to HbTCTP1, HbTCTP also indicated antioxidant activity in metal-catalyzed oxidation (MCO) system. Our results are useful for further understanding the molecular characterization and expression profiles of HbTCTP, but also lay a solid foundation for elucidating the function of HbTCTP in rubber tree. PMID:27375647

  9. Rubber

    NASA Astrophysics Data System (ADS)

    Graves, D. F.

    The word "rubber" immediately brings to mind materials that are highly flexible and will snap back to their original shape after being stretched. In this chapter a variety of materials are discussed that possess this odd characteristics. There will also be a discussion on the mechanism of this "elastic retractive force." Originally, rubber meant the gum collected from a tree growing in Brazil. The term "rubber" was coined for this material by the English chemist Joseph Priestley, who noted that it was effective for removing pencil marks from paper. Today, in addition to Priestley's natural product, many synthetic materials are made that possess these characteristics and many other properties. The common features of these materials are that they are made up of long-chain molecules that are amorphous (not crystalline), and the chains are above their glass transition temperature at room temperature.

  10. Transcriptome analyses reveal molecular mechanism underlying tapping panel dryness of rubber tree (Hevea brasiliensis).

    PubMed

    Li, Dejun; Wang, Xuncheng; Deng, Zhi; Liu, Hui; Yang, Hong; He, Guangming

    2016-03-23

    Tapping panel dryness (TPD) is a serious threat to natural rubber yields from rubber trees, but the molecular mechanisms underlying TPD remain poorly understood. To identify TPD-related genes and reveal these molecular mechanisms, we sequenced and compared the transcriptomes of bark between healthy and TPD trees. In total, 57,760 assembled genes were obtained and analyzed in details. In contrast to healthy rubber trees, 5652 and 2485 genes were up- or downregulated, respectively, in TPD trees. The TPD-related genes were significantly enriched in eight GO terms and five KEGG pathways and were closely associated with ROS metabolism, programmed cell death and rubber biosynthesis. Our results suggest that rubber tree TPD is a complex process involving many genes. The observed lower rubber yield from TPD trees might result from lower isopentenyl diphosphate (IPP) available for rubber biosynthesis and from downregulation of the genes in post-IPP steps of rubber biosynthesis pathway. Our results not only extend our understanding of the complex molecular events involved in TPD but also will be useful for developing effective measures to control TPD of rubber trees.

  11. Transcriptome analyses reveal molecular mechanism underlying tapping panel dryness of rubber tree (Hevea brasiliensis)

    PubMed Central

    Li, Dejun; Wang, Xuncheng; Deng, Zhi; Liu, Hui; Yang, Hong; He, Guangming

    2016-01-01

    Tapping panel dryness (TPD) is a serious threat to natural rubber yields from rubber trees, but the molecular mechanisms underlying TPD remain poorly understood. To identify TPD-related genes and reveal these molecular mechanisms, we sequenced and compared the transcriptomes of bark between healthy and TPD trees. In total, 57,760 assembled genes were obtained and analyzed in details. In contrast to healthy rubber trees, 5652 and 2485 genes were up- or downregulated, respectively, in TPD trees. The TPD-related genes were significantly enriched in eight GO terms and five KEGG pathways and were closely associated with ROS metabolism, programmed cell death and rubber biosynthesis. Our results suggest that rubber tree TPD is a complex process involving many genes. The observed lower rubber yield from TPD trees might result from lower isopentenyl diphosphate (IPP) available for rubber biosynthesis and from downregulation of the genes in post-IPP steps of rubber biosynthesis pathway. Our results not only extend our understanding of the complex molecular events involved in TPD but also will be useful for developing effective measures to control TPD of rubber trees. PMID:27005401

  12. Variation of Soil Bacterial Communities in a Chronosequence of Rubber Tree (Hevea brasiliensis) Plantations

    PubMed Central

    Zhou, Yu-Jie; Li, Jian-Hua; Ross Friedman, Cynthia; Wang, Hua-Feng

    2017-01-01

    Regarding rubber tree plantations, researchers lack a basic understanding of soil microbial communities; specifically, little is known about whether or not soil microbial variation is correlated with succession in these plantations. In this paper, we used high-throughput sequencing of the 16S rRNA gene to investigate the diversity and composition of the soil bacterial communities in a chronosequence of rubber tree plantations that were 5, 10, 13, 18, 25, and 30 years old. We determined that: (1) Soil bacterial diversity and composition show changes over the succession stages of rubber tree plantations. The diversity of soil bacteria were highest in 10, 13, and 18 year-old rubber tree plantations, followed by 30 year-old rubber tree plantations, whereas 5 and 25 year-old rubber tree plantations had the lowest values for diversity. A total of 438,870 16S rDNA sequences were detected in 18 soil samples from six rubber tree plantations, found in 28 phyla, 66 classes, 139 orders, 245 families, 355 genera, and 645 species, with 1.01% sequences from unclassified bacteria. The dominant phyla were Acidobacteria, Proteobacteria, Chloroflexi, Actinobacteria, and Verrucomicrobia (relative abundance large than 3%). There were differences in soil bacterial communities among different succession stages of rubber tree plantation. (2) Soil bacteria diversity and composition in the different stages was closely related to pH, vegetation, soil nutrient, and altitude, of which pH, and vegetation were the main drivers. PMID:28611794

  13. Ficus elastica-The Indian rubber tree-an underutilized promising multi-use species

    USDA-ARS?s Scientific Manuscript database

    Ficus elastica known as the Indian rubber tree has a white, milky latex that is a source of natural rubber was analyzed for its phytochemicals as an intermediate energy source. The tree produces a high quantity of protein and oil (24.5 and 6.1% respectively). The polyphenol content was 4.2%, and hyd...

  14. Identification of expression profiles of tapping panel dryness (TPD) associated genes from the latex of rubber tree (Hevea brasiliensis Muell. Arg.).

    PubMed

    Venkatachalam, Perumal; Thulaseedharan, Arjunan; Raghothama, Kashchandra

    2007-07-01

    Tapping panel dryness (TPD) occurrence in high latex yielding rubber tree (Hevea brasiliensis) is characterized by the partial or complete cessation of latex flow upon tapping leading to severe loss in natural rubber production around the world. The goal of this study was to identify genes whose mRNA transcript levels are differentially regulated in rubber tree during the onset of TPD. To isolate TPD responsive genes, two cDNA libraries (forward and reverse) from total RNA isolated from latex of healthy and TPD trees were constructed using suppression subtractive hybridization (SSH) method. In total, 1,079 EST clones were obtained from two cDNA libraries and screened by reverse Northern blot analysis. Screening results revealed that about 352 clones were differentially regulated and they were selected for sequencing. Based on the nucleotide sequence data, the putative functions of cDNA clones were predicted by BLASTX/BLASTN analysis. Among these, 64 were genes whose function had been previously identified while the remaining clones were genes with either unknown protein function or insignificant similarity to other protein/DNA/EST sequences in existing databases. RT-PCR analysis was carried out to validate the up-regulated genes from both the libraries. Among them, two genes were strongly down-regulated in TPD trees. The level of mRNA transcripts of these two genes was further examined by conventional Northern and RT-PCR analysis. Results indicated that the expression level of two genes was significantly lower in TPD trees compared to healthy trees. Many TPD associated genes were also up-regulated in TPD trees suggesting that they may be involved in triggering programmed cell death (PCD) during the onset of TPD syndrome. The results presented here demonstrate that SSH technique provides a powerful complementary approach for the identification of TPD related genes from rubber tree.

  15. In-depth proteome analysis of the rubber particle of Hevea brasiliensis (para rubber tree).

    PubMed

    Dai, Longjun; Kang, Guijuan; Li, Yu; Nie, Zhiyi; Duan, Cuifang; Zeng, Rizhong

    2013-05-01

    The rubber particle is a special organelle in which natural rubber is synthesised and stored in the laticifers of Hevea brasiliensis. To better understand the biological functions of rubber particles and to identify the candidate rubber biosynthesis-related proteins, a comprehensive proteome analysis was performed on H. brasiliensis rubber particles using shotgun tandem mass spectrometry profiling approaches-resulting in a thorough report on the rubber particle proteins. A total of 186 rubber particle proteins were identified, with a range in relative molecular mass of 3.9-194.2 kDa and in isoelectric point values of 4.0-11.2. The rubber particle proteins were analysed for gene ontology and could be categorised into eight major groups according to their functions: including rubber biosynthesis, stress- or defence-related responses, protein processing and folding, signal transduction and cellular transport. In addition to well-known rubber biosynthesis-related proteins such as rubber elongation factor (REF), small rubber particle protein (SRPP) and cis-prenyl transferase (CPT), many proteins were firstly identified to be on the rubber particles, including cyclophilin, phospholipase D, cytochrome P450, small GTP-binding protein, clathrin, eukaryotic translation initiation factor, annexin, ABC transporter, translationally controlled tumour protein, ubiquitin-conjugating enzymes, and several homologues of REF, SRPP and CPT. A procedure of multiple reaction monitoring was established for further protein validation. This comprehensive proteome data of rubber particles would facilitate investigation into molecular mechanisms of biogenesis, self-homeostasis and rubber biosynthesis of the rubber particle, and might serve as valuable biomarkers in molecular breeding studies of H. brasiliensis and other alternative rubber-producing species.

  16. Transcriptome analysis reveals novel features of the molecular events occurring in the laticifers of Hevea brasiliensis (para rubber tree).

    PubMed

    Ko, Jae-Heung; Chow, Keng-See; Han, Kyung-Hwan

    2003-11-01

    Latex of Hevea brasiliensis (Willd. ex A, Juss.) Mull. Arg. (Brazilian rubber tree) contains 30-50% (w/w) of natural rubber (cis-1,4-polyisoprene), which is an important raw material for many industrial uses. In order to gain insights into the molecular events occurring in latex, we analyzed more than 20,000 cDNA-AFLP-based TDFs (transcription-derived fragments) and 1176 ESTs. The results revealed several novel features of the latex transcriptome. First, the repertoire of the genes expressed in latex is unique. Only seven gene families accounted for more than 51% of the latex transcriptome. Among them, two of the most abundant ESTs were the genes encoding rubber particle proteins REF (rubber elongation factor) and SRPP (small rubber particle protein), comprising 29% of the total ESTs. Unexpectedly, several genes involved in the rubber biosynthesis were expressed at low levels in the latex. In fact, genes encoding cis -prenyltransferase (CPT), a potential candidate for rubber polymerase, were not present in the EST pool because of their low expression level. However, we were able to clone four full-length cDNAs by screening the same latex cDNA library used in the EST analysis and confirmed their enzyme activity in vitro. The second most abundant transcripts were defense- or stress-related genes, suggesting that defense is one of the functions of laticifers. Finally, the presence of the non-mevalonate DXP/MEP pathway for IPP synthesis in latex was noted by up-regulation of the 1-deoxy-D-xylulose 5-phosphate synthase gene.

  17. [Soil moisture content and fine root biomass of rubber tree (Hevea brasiliensis) plantations at different ages].

    PubMed

    Lin, Xi-Hao; Chen, Qiu-Bo; Hua, Yuan-Gang; Yang, Li-Fu; Wang, Zhen-Hui

    2011-02-01

    By using soil core sampling method, this paper studied the soil moisture regime of rubber plantations and the fine root biomass of Hevea brasiliensis in immature period (5 a), early yielding period (9 a), and peak yielding period (16 a). With the increasing age of rubber trees, the soil moisture content of rubber plantations increased but the fine root biomass decreased. The soil moisture content at the depth of 0-60 cm in test rubber plantations increased with soil depth, and presented a double-peak pattern over the period of one year. The fine root biomass of rubber trees at different ages had the maximum value in the top 10 cm soil layers and decreased with soil depth, its seasonal variation also showed a double-peak pattern, but the peak values appeared at different time. Soil moisture content and soil depth were the main factors affecting the fine root biomass of H. brasiliensis.

  18. Sugar metabolism and developmental stages of rubber tree (Hevea brasiliensis L.) seeds.

    PubMed

    de Souza, Genaina Aparecida; Dias, Denise Cunha Fernandes Dos Santos; Pimenta, Thaline Martins; Almeida, Andrea Lanna; Picoli, Edgard Augusto de Toledo; Alvarenga, Antônio de Pádua; da Silva, José Cleydson Ferreira

    2017-10-09

    Changes in the concentration of sugars and sucrose metabolism enzymes can characterize the developmental stages of a seed. In recalcitrant species such as Hevea brasiliensis L., little is known about these changes. We aimed to evaluate the three main stages of development of rubber tree seeds - histodifferentiation, cell elongation and accumulation of reserves. The activities of acid and neutral invertases (E.C. 3.2.1.26) and sucrose synthase (EC 2.4.1.13), and the concentrations of reducing sugars (RS), total soluble sugars (TSS), and sucrose (Suc) were determined concomitantly with the histochemical and anatomical evaluation of seed structure. Histodifferentiation in rubber tree seeds occurs up to 75 days after anthesis (DAA). The concentration of RS is high and of Suc is low during seed histodifferentiation, which occurs along with a visible increase in the number of cell divisions. After that period, there is an increase in the concentration of Suc (mg g(-1) ) and in the number and size of starch granules, and a decrease in the concentration of RS (mg g(-1) ). At that point, cell elongation occurs. At 135 DAA, there is an inversion in the concentration of these two sugars and an increase in reserve accumulation. Thus, in seeds of the evaluated clone, the period up to 75 DAA is characterized as the histodifferentiation stage, while from that time up to 120 DAA the cell elongation stage takes place. The final stage of seed maturation and reserve accumulation begins at 135 DAA, and the seed, including the embryo, is completely formed at 175 DAA. This article is protected by copyright. All rights reserved.

  19. Rubber.

    ERIC Educational Resources Information Center

    Krishen, Anoop

    1989-01-01

    This review covers methods for identification, characterization, and determination of rubber and materials in rubber. Topics include: general information, nuclear magnetic resonance spectroscopy, infrared spectroscopy, thermal methods, gel permeation chromatography, size exclusion chromatography, analysis related to safety and health, and…

  20. Oil Palm and Rubber Tree Water Use Patterns: Effects of Topography and Flooding

    PubMed Central

    Hardanto, Afik; Röll, Alexander; Niu, Furong; Meijide, Ana; Hendrayanto; Hölscher, Dirk

    2017-01-01

    Oil palm and rubber plantations extend over large areas and encompass heterogeneous site conditions. In periods of high rainfall, plants in valleys and at riparian sites are more prone to flooding than plants at elevated topographic positions. We asked to what extent topographic position and flooding affect oil palm and rubber tree water use patterns and thereby influence spatial and temporal heterogeneity of transpiration. In an undulating terrain in the lowlands of Jambi, Indonesia, plantations of the two species were studied in plot pairs consisting of upland and adjacent valley plots. All upland plots were non-flooded, whereas the corresponding valley plots included non-flooded, long-term flooded, and short-term flooded conditions. Within each plot pair, sap flux densities in palms or trees were monitored simultaneously with thermal dissipation probes. In plot pairs with non-flooded valleys, sap flux densities of oil palms were only slightly different between the topographic positions, whereas sap flux densities of rubber trees were higher in the valley than at the according upland site. In pairs with long-term flooded valleys, sap flux densities in valleys were lower than at upland plots for both species, but the reduction was far less pronounced in oil palms than in rubber trees (-22 and -45% in maximum sap flux density, respectively). At these long-term flooded valley plots palm and tree water use also responded less sensitively to fluctuations in micrometeorological variables than at upland plots. In short-term flooded valley plots, sap flux densities of oil palm were hardly affected by flooding, but sap flux densities of rubber trees were reduced considerably. Topographic position and flooding thus affected water use patterns in both oil palms and rubber trees, but the changes in rubber trees were much more pronounced: compared to non-flooded upland sites, the different flooding conditions at valley sites amplified the observed heterogeneity of plot mean

  1. Oil Palm and Rubber Tree Water Use Patterns: Effects of Topography and Flooding.

    PubMed

    Hardanto, Afik; Röll, Alexander; Niu, Furong; Meijide, Ana; Hendrayanto; Hölscher, Dirk

    2017-01-01

    Oil palm and rubber plantations extend over large areas and encompass heterogeneous site conditions. In periods of high rainfall, plants in valleys and at riparian sites are more prone to flooding than plants at elevated topographic positions. We asked to what extent topographic position and flooding affect oil palm and rubber tree water use patterns and thereby influence spatial and temporal heterogeneity of transpiration. In an undulating terrain in the lowlands of Jambi, Indonesia, plantations of the two species were studied in plot pairs consisting of upland and adjacent valley plots. All upland plots were non-flooded, whereas the corresponding valley plots included non-flooded, long-term flooded, and short-term flooded conditions. Within each plot pair, sap flux densities in palms or trees were monitored simultaneously with thermal dissipation probes. In plot pairs with non-flooded valleys, sap flux densities of oil palms were only slightly different between the topographic positions, whereas sap flux densities of rubber trees were higher in the valley than at the according upland site. In pairs with long-term flooded valleys, sap flux densities in valleys were lower than at upland plots for both species, but the reduction was far less pronounced in oil palms than in rubber trees (-22 and -45% in maximum sap flux density, respectively). At these long-term flooded valley plots palm and tree water use also responded less sensitively to fluctuations in micrometeorological variables than at upland plots. In short-term flooded valley plots, sap flux densities of oil palm were hardly affected by flooding, but sap flux densities of rubber trees were reduced considerably. Topographic position and flooding thus affected water use patterns in both oil palms and rubber trees, but the changes in rubber trees were much more pronounced: compared to non-flooded upland sites, the different flooding conditions at valley sites amplified the observed heterogeneity of plot mean

  2. Initial results of the spatial distribution of rubber trees in Peninsular Malaysia using remotely sensed data for biomass estimate

    NASA Astrophysics Data System (ADS)

    Shidiq, I. P. A.; Ismail, M. H.; Kamarudin, N.

    2014-02-01

    The preservation and sustainable management of forest and other land cover ecosystems such as rubber trees will help addressing two major recent issues: climate change and bio-resource energy. The rubber trees are dominantly distributed in the Negeri Sembilan and Kedah on the west coast side of Peninsular Malaysia. This study is aimed to analyse the spatial distribution and biomass of rubber trees in Peninsular Malaysia with special emphasis in Negeri Sembilan State. Geospatial data from remote sensors are used to tackle the time and labour consuming problem due to the large spatial coverage and the need of continuous temporal data. Remote sensing imagery used in this study is a Landsat 5 TM. The image from optical sensor was used to sense the rubber trees and further classified rubber tree by different age.

  3. De novo assembly and transcriptome analysis of the rubber tree (Hevea brasiliensis) and SNP markers development for rubber biosynthesis pathways.

    PubMed

    Mantello, Camila Campos; Cardoso-Silva, Claudio Benicio; da Silva, Carla Cristina; de Souza, Livia Moura; Scaloppi Junior, Erivaldo José; de Souza Gonçalves, Paulo; Vicentini, Renato; de Souza, Anete Pereira

    2014-01-01

    Hevea brasiliensis (Willd. Ex Adr. Juss.) Muell.-Arg. is the primary source of natural rubber that is native to the Amazon rainforest. The singular properties of natural rubber make it superior to and competitive with synthetic rubber for use in several applications. Here, we performed RNA sequencing (RNA-seq) of H. brasiliensis bark on the Illumina GAIIx platform, which generated 179,326,804 raw reads on the Illumina GAIIx platform. A total of 50,384 contigs that were over 400 bp in size were obtained and subjected to further analyses. A similarity search against the non-redundant (nr) protein database returned 32,018 (63%) positive BLASTx hits. The transcriptome analysis was annotated using the clusters of orthologous groups (COG), gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Pfam databases. A search for putative molecular marker was performed to identify simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). In total, 17,927 SSRs and 404,114 SNPs were detected. Finally, we selected sequences that were identified as belonging to the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, which are involved in rubber biosynthesis, to validate the SNP markers. A total of 78 SNPs were validated in 36 genotypes of H. brasiliensis. This new dataset represents a powerful information source for rubber tree bark genes and will be an important tool for the development of microsatellites and SNP markers for use in future genetic analyses such as genetic linkage mapping, quantitative trait loci identification, investigations of linkage disequilibrium and marker-assisted selection.

  4. De Novo Assembly and Transcriptome Analysis of the Rubber Tree (Hevea brasiliensis) and SNP Markers Development for Rubber Biosynthesis Pathways

    PubMed Central

    Mantello, Camila Campos; Cardoso-Silva, Claudio Benicio; da Silva, Carla Cristina; de Souza, Livia Moura; Scaloppi Junior, Erivaldo José; de Souza Gonçalves, Paulo; Vicentini, Renato; de Souza, Anete Pereira

    2014-01-01

    Hevea brasiliensis (Willd. Ex Adr. Juss.) Muell.-Arg. is the primary source of natural rubber that is native to the Amazon rainforest. The singular properties of natural rubber make it superior to and competitive with synthetic rubber for use in several applications. Here, we performed RNA sequencing (RNA-seq) of H. brasiliensis bark on the Illumina GAIIx platform, which generated 179,326,804 raw reads on the Illumina GAIIx platform. A total of 50,384 contigs that were over 400 bp in size were obtained and subjected to further analyses. A similarity search against the non-redundant (nr) protein database returned 32,018 (63%) positive BLASTx hits. The transcriptome analysis was annotated using the clusters of orthologous groups (COG), gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Pfam databases. A search for putative molecular marker was performed to identify simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). In total, 17,927 SSRs and 404,114 SNPs were detected. Finally, we selected sequences that were identified as belonging to the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, which are involved in rubber biosynthesis, to validate the SNP markers. A total of 78 SNPs were validated in 36 genotypes of H. brasiliensis. This new dataset represents a powerful information source for rubber tree bark genes and will be an important tool for the development of microsatellites and SNP markers for use in future genetic analyses such as genetic linkage mapping, quantitative trait loci identification, investigations of linkage disequilibrium and marker-assisted selection. PMID:25048025

  5. Change Analysis of the Spectral Characteristics of Rubber Trees at Canopy and Leaf Scales during the Brazilian Autumn

    NASA Astrophysics Data System (ADS)

    Amaral, C. H.; Almeida, T. I. R.; Quitério, G. C. M.; Alves, M. N.; Souza Filho, C. R.

    2012-07-01

    The objective of this work is to investigate the hyperspectral remote sensing potential to detect spectral changes undergone by clones of two rubber trees within Brazilian Autumn, with decrease of rain, temperature and photoperiod between May and June. Indirectly, we also analyze the ability of the data to help discriminating the clones at two dates in autumn. The average canopy spectra of the stands were obtained with two overpasses of the ProSpecTIR-VS airborne hyperspectral sensor (357 bands between 400-2,500 nm; spatial resolution of 1m) by 14th May and 17th June, in 2010 year. Additionally measurements of leaf spectra were taken in the same dates, but in the 2011 year. Considering the analysis of the spectra measured from the three stands, this indicates that spectral differences in the VIS (400-700 nm) region are of genetic origin and occur regardless of environmental conditions and period of data collection. In the NIR (700-1,300 nm) range, the environmental factors predominate in the two periods of data collection. The SWIR (1,300-2,500 nm) displayed the largest differences between the months of data collection. In May, the relationship between stands indicated the prevalence of environmental aspects. However, in June, the stands and clones spectral behaviour indicates that as the temperature, the rainfall and the photoperiod are lower closer to winter, the SWIR can be effectively used to discriminate and map these clones separately.

  6. Rubber Trees Demonstrate a Clear Retranslocation Under Seasonal Drought and Cold Stresses

    PubMed Central

    Li, Yuwu; Lan, Guoyu; Xia, Yujie

    2016-01-01

    Having been introduced to the northern edge of Asian tropics, the rubber tree (Hevea brasiliensis) has become deciduous in this climate with seasonal drought and cold stresses. To determine its internal nutrient strategy during leaf senescence and deciduous periods, we investigated mature leaf and senescent leaf nutrients, water-soluble soil nutrients and characteristics of soil microbiota in nine different ages of monoculture rubber plantations. Rubber trees demonstrate complicated retranslocation of N, P, and K during foliar turnover. Approximately 50.26% of leaf nutrients and 21.47% of soil nutrients were redistributed to the rubber tree body during the leaf senescence and withering stages. However, no significant changes in the structure- or function-related properties of soil microbes were detected. These nutrient retranslocation strategy may be important stress responses. In the nutrient retranslocation process, soil plays a dual role as nutrient supplier and nutrient “bank.” Soil received the nutrients from abscised leaves, and also supplied nutrients to trees in the non-growth stage. Nutrient absorption and accumulation began before the leaves started to wither and fall. PMID:28066467

  7. Rubber Trees Demonstrate a Clear Retranslocation Under Seasonal Drought and Cold Stresses.

    PubMed

    Li, Yuwu; Lan, Guoyu; Xia, Yujie

    2016-01-01

    Having been introduced to the northern edge of Asian tropics, the rubber tree (Hevea brasiliensis) has become deciduous in this climate with seasonal drought and cold stresses. To determine its internal nutrient strategy during leaf senescence and deciduous periods, we investigated mature leaf and senescent leaf nutrients, water-soluble soil nutrients and characteristics of soil microbiota in nine different ages of monoculture rubber plantations. Rubber trees demonstrate complicated retranslocation of N, P, and K during foliar turnover. Approximately 50.26% of leaf nutrients and 21.47% of soil nutrients were redistributed to the rubber tree body during the leaf senescence and withering stages. However, no significant changes in the structure- or function-related properties of soil microbes were detected. These nutrient retranslocation strategy may be important stress responses. In the nutrient retranslocation process, soil plays a dual role as nutrient supplier and nutrient "bank." Soil received the nutrients from abscised leaves, and also supplied nutrients to trees in the non-growth stage. Nutrient absorption and accumulation began before the leaves started to wither and fall.

  8. Molecular and biochemical characterization of a cyanogenic β-glucosidase in the inner bark tissues of rubber tree (Hevea brasiliensis Muell. Arg.).

    PubMed

    Tian, Wei-Min; Zhang, Hua; Yang, Shu-Guang; Shi, Min-Jing; Wang, Xu-Chu; Dai, Long-Jun; Chen, Yue-Yi

    2013-05-15

    Tapping causes the loss of large amounts of latex from laticifers and subsequently enhances latex regeneration, a high carbon- and nitrogen-cost activity in rubber tree. It is suggested that a 67 kDa protein associated with protein-storing cells in the inner bark tissues of rubber tree plays an important role in meeting the nitrogen demand for latex regeneration. Here, the 67 kDa protein was further characterized by a combination of cell biological, molecular biological and biochemical techniques. Immunogold labeling showed that the 67 kDa protein was specifically localized in the central vacuole of protein-storing cells. A full-length cDNA, referred to as HbVSP1, was cloned. The HbVSP1 contained a 1584 bp open reading frame encoding a protein of 527 amino acids. The putative protein HbVSP1 shared high identity with the P66 protein from rubber tree and proteins of the linamarase, and bg1A from cassava (Manihot esculenta). HbVSP1 contained the active site sequences of β-glucosidase, TFNEP and I/VTENG. In vitro analysis showed that the 67 kDa protein exhibited the activity of both β-glucosidase and linamarase and was thus characterized as a cyanogenic β-glucosidase. Proteins immuno-related to the 67 kDa protein were present in leaves and lutoids of laticifers. Tapping down-regulated the expression of HbVSP1, but up-regulated the expression of genes encoding the key enzymes for rubber biosynthesis, while the effect of resting from tapping was the reverse. Taken together, the results suggest that the 67 kDa protein is a vacuole-localized cyanogenic β-glucosidase encoded by HbVSP1 and may have a role in nitrogen storage in inner bark tissues of trunk during the leafless periods when rubber tree is rested from tapping.

  9. Involvement of ethylene-responsive microRNAs and their targets in increased latex yield in the rubber tree in response to ethylene treatment.

    PubMed

    Pramoolkit, Porawee; Lertpanyasampatha, Manassawe; Viboonjun, Unchera; Kongsawadworakul, Panida; Chrestin, Hervé; Narangajavana, Jarunya

    2014-11-01

    The rubber tree is an economically important plant that produces natural rubber for various industrial uses. The application of ethylene contributes to increased latex production in rubber trees; however, the molecular biology behind the effects of ethylene on latex yield remains to be elucidated. Recently, the intersection between microRNA (miRNA) regulation and phytohormone responses has been revealed. Insight into the regulation of miRNAs and their target genes should help to determine the functional importance of miRNAs as well as the role of miRNAs in signaling under ethylene stimulation in the rubber tree. In this study, hbr-miR159 and hbr-miR166 were down-regulated in bark under ethylene treatment. The ethylene also down-regulated ATHB15-like (Class III Homeodomain Leucine Zipper, HD-ZIP III) which have been extensively implicated in the regulation of primary and secondary vascular tissue pattern formation. The strong negative-regulation of ARF6/ARF8 caused by hbr-miR167 involved in an attenuation of vascular development and may gradually lead to bark dryness syndrome in the long term ethylene treatment. The negative correlation of hbr-miR172 and its target REF3 in the inner soft bark under ethylene treatment results in dramatic increases in latex yield in the ethylene-sensitive clone of the rubber tree. The overall results suggested that the differential expression of HD-ZIP III, miR167/ARF6, ARF8, and miR172/REF3 and related genes may play possible roles in the response to ethylene treatment, resulting in longer latex flow and increased latex yield.

  10. Rubber

    SciTech Connect

    Krishen, A.

    1987-01-01

    This review covers methods for identification, characterization, and determination of rubber and materials in rubber. Techniques discussed include: nuclear magnetic resonance; Fourier transform infrared spectroscopy; UV spectroscopy; differential scanning calorimetry; thermogravimetric analysis; thermomechanical analysis; gel permeation chromatography; size exclusion chromatography; gas chromatography; mass spectrometry; pyrolysis; extraction; scanning selectron microscopy; polarization microscopy; x-ray fluorescence; x-ray scattering; angular light scattering; acoustic scattering; and vapor pressure osmometry.

  11. SNP identification from RNA sequencing and linkage map construction of rubber tree for anchoring the draft genome.

    PubMed

    Shearman, Jeremy R; Sangsrakru, Duangjai; Jomchai, Nukoon; Ruang-Areerate, Panthita; Sonthirod, Chutima; Naktang, Chaiwat; Theerawattanasuk, Kanikar; Tragoonrung, Somvong; Tangphatsornruang, Sithichoke

    2015-01-01

    Hevea brasiliensis, or rubber tree, is an important crop species that accounts for the majority of natural latex production. The rubber tree nuclear genome consists of 18 chromosomes and is roughly 2.15 Gb. The current rubber tree reference genome assembly consists of 1,150,326 scaffolds ranging from 200 to 531,465 bp and totalling 1.1 Gb. Only 143 scaffolds, totalling 7.6 Mb, have been placed into linkage groups. We have performed RNA-seq on 6 varieties of rubber tree to identify SNPs and InDels and used this information to perform target sequence enrichment and high throughput sequencing to genotype a set of SNPs in 149 rubber tree offspring from a cross between RRIM 600 and RRII 105 rubber tree varieties. We used this information to generate a linkage map allowing for the anchoring of 24,424 contigs from 3,009 scaffolds, totalling 115 Mb or 10.4% of the published sequence, into 18 linkage groups. Each linkage group contains between 319 and 1367 SNPs, or 60 to 194 non-redundant marker positions, and ranges from 156 to 336 cM in length. This linkage map includes 20,143 of the 69,300 predicted genes from rubber tree and will be useful for mapping studies and improving the reference genome assembly.

  12. Diversity of root-associated arbuscular mycorrhizal fungal communities in a rubber tree plantation chronosequence in Northeast Thailand.

    PubMed

    Herrmann, Laetitia; Lesueur, Didier; Bräu, Lambert; Davison, John; Jairus, Teele; Robain, Henri; Robin, Agnès; Vasar, Martti; Wiriyakitnateekul, Wanpen; Öpik, Maarja

    2016-11-01

    Rubber tree (Hevea brasiliensis) is of major economic importance in Southeast Asia and for small land holders in Thailand in particular. Due to the high value of latex, plantations are expanding into unsuitable areas, such as the northeast province of Thailand where soil fertility is very low and therefore appropriate management practices are of primary importance. Arbuscular mycorrhizal fungi (AMF) contribute to plant growth through a range of mechanisms and could play a key role in a more sustainable management of the rubber plantations. We described the diversity of AMF associated with rubber tree roots in Northeast Thailand in relation to tree age and soil parameters along a chronosequence of rubber tree plantations. Cassava fields were included for comparison. Rubber tree and cassava roots harbored high diversity of AMF (111 Virtual Taxa, VT), including 20 novel VT. AMF VT richness per sample was consistently high (per site mean 16 to 21 VT per sample) along the chronosequence and was not related to soil properties. The composition of AMF communities differed between cassava and rubber tree plantations and was influenced by soil texture and nutrient content (sand, K, P, Ca). AMF community composition gradually shifted with the age of the trees. Our results suggest that the high diversity of AMF in this region is potentially significant for maintaining high functionality of AMF communities.

  13. De novo hybrid assembly of the rubber tree genome reveals evidence of paleotetraploidy in Hevea species

    PubMed Central

    Pootakham, Wirulda; Sonthirod, Chutima; Naktang, Chaiwat; Ruang-Areerate, Panthita; Yoocha, Thippawan; Sangsrakru, Duangjai; Theerawattanasuk, Kanikar; Rattanawong, Ratchanee; Lekawipat, Napawan; Tangphatsornruang, Sithichoke

    2017-01-01

    Para rubber tree (Hevea brasiliensis) is an important economic species as it is the sole commercial producer of high-quality natural rubber. Here, we report a de novo hybrid assembly of BPM24 accession, which exhibits resistance to major fungal pathogens in Southeast Asia. Deep-coverage 454/Illumina short-read and Pacific Biosciences (PacBio) long-read sequence data were acquired to generate a preliminary draft, which was subsequently scaffolded using a long-range “Chicago” technique to obtain a final assembly of 1.26 Gb (N50 = 96.8 kb). The assembled genome contains 69.2% repetitive sequences and has a GC content of 34.31%. Using a high-density SNP-based genetic map, we were able to anchor 28.9% of the genome assembly (363 Mb) associated with over two thirds of the predicted protein-coding genes into rubber tree’s 18 linkage groups. These genetically anchored sequences allowed comparative analyses of the intragenomic homeologous synteny, providing the first concrete evidence to demonstrate the presence of paleotetraploidy in Hevea species. Additionally, the degree of macrosynteny conservation observed between rubber tree and cassava strongly supports the hypothesis that the paleotetraploidization event took place prior to the divergence of the Hevea and Manihot species. PMID:28150702

  14. Identification of lipopeptides produced by Bacillus subtilis Czk1 isolated from the aerial roots of rubber trees.

    PubMed

    He, C P; Fan, L Y; Wu, W H; Liang, Y Q; Li, R; Tang, W; Zheng, X L; Xiao, Y N; Liu, Z X; Zheng, F C

    2017-02-23

    We obtained a strain of Bacillus subtilis, which we named Czk1, from the aerial roots of rubber trees. This bacterial isolate exhibits strong antagonistic activity against Ganoderma pseudoferreum, Phellinus noxius, Helicobasidium compactum, Rigidoporus lignosus, Sphaerostilbe repens, and Colletotrichum gloeosporioides. Our earlier research has shown that the antagonistic activity of a fermentation supernatant Czk1 isolate produces a complex mixture of lipopeptides. In this study, we used methanol to extract crude lipopeptides, purified them using a Sephadex G-25 column, cloned the lipopeptide genes, and analyzed purified fractions by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) to identify the lipopeptides from B. subtilis strain Czk1. The cloned lipopeptide genes included those that encode the enzymes lpa, ituD, sfp, and fenB. The crude lipopeptides were purified and found in five fractions. Further analysis revealed that five fractions of the purified composition contained members of the surfactin, iturin, fengycin, and bacillomycin families of antibiotics. This suggests that these lipopeptides from strain Czk1 have potential as plant disease biocontrol agents.

  15. Distribution of molar mass and branching index of natural rubber from Hevea brasiliensis trees of different age by size exclusion chromatography coupled with online viscometry.

    PubMed

    Phan, T N; Lan, N T; Nga, N T

    2004-05-01

    Natural rubber from hevea brasiliensis trees (Thailand, RRIM 600 clone) of different age (8, 20, and 35 years) were characterized by size exclusion chromatography coupled with online viscometry according to their distribution of molar mass and branching index at a temperature of 70 degrees C using cyclohexane as solvent. Washing with an aqueous solution of sodium dodecylsulfate and subsequent saponification purified the natural rubber samples. With this procedure physical branching points caused by phospholipids, proteins and hydrophobic terminal units, mainly fatty acids, of the natural rubber (cis-1,4-polyisoprene) molecule, could be removed leading to completely soluble polymer samples. All samples investigated possess a very broad (10 to 50,000 kg/mol) and distinct bimodal molar mass distribution. With increasing age the peak area in the low molar mass region decreases favoring the peak area in the high molar mass region. By plotting the branching index as a function of the both, the molar mass and the age of the trees.

  16. HbNIN2, a cytosolic alkaline/neutral-invertase, is responsible for sucrose catabolism in rubber-producing laticifers of Hevea brasiliensis (para rubber tree).

    PubMed

    Liu, Shujin; Lan, Jixian; Zhou, Binhui; Qin, Yunxia; Zhou, Yihua; Xiao, Xiaohu; Yang, Jianghua; Gou, Jiqing; Qi, Jiyan; Huang, Yacheng; Tang, Chaorong

    2015-04-01

    In Hevea brasiliensis, an alkaline/neutral invertase (A/N-Inv) is responsible for sucrose catabolism in latex (essentially the cytoplasm of rubber-producing laticifers, the source of natural rubber) and implicated in rubber yield. However, neither the gene encoding this enzyme nor its molecular and biochemical properties have been well documented. Three Hevea A/N-Inv genes, namely HbNIN1, 2 and 3, were first cloned and characterized in planta and in Escherichia coli. Cellular localizations of HbNIN2 mRNA and protein were probed. From latex, active A/N-Inv proteins were purified, identified, and explored for enzymatic properties. HbNIN2 was identified as the major A/N-Inv gene functioning in latex based on its functionality in E. coli, its latex-predominant expression, the conspicuous localization of its mRNA and protein in the laticifers, and its expressional correlation with rubber yield. An active A/N-Inv protein was partially purified from latex, and determined as HbNIN2. The enhancement of HbNIN2 enzymatic activity by pyridoxal is peculiar to A/N-Invs in other plants. We conclude that HbNIN2, a cytosolic A/N-Inv, is responsible for sucrose catabolism in rubber laticifers. The results contribute to the studies of sucrose catabolism in plants as a whole and natural rubber synthesis in particular.

  17. Mathematical analysis and modeling of epidemics of rubber tree root diseases: Probability of infection of an individual tree

    SciTech Connect

    Chadoeuf, J.; Joannes, H.; Nandris, D.; Pierrat, J.C.

    1988-12-01

    The spread of root diseases in rubber tree (Hevea brasiliensis) due to Rigidoporus lignosus and Phellinus noxius was investigated epidemiologically using data collected every 6 month during a 6-year survey in a plantation. The aim of the present study is to see what factors could predict whether a given tree would be infested at the following inspection. Using a qualitative regression method we expressed the probability of pathogenic attack on a tree in terms of three factors: the state of health of the surrounding trees, the method used to clear the forest prior to planting, and evolution with time. The effects of each factor were ranked, and the roles of the various classes of neighbors were established and quantified. Variability between successive inspections was small, and the method of forest clearing was important only while primary inocula in the soil were still infectious. The state of health of the immediate neighbors was most significant; more distant neighbors in the same row had some effect; interrow spread was extremely rare. This investigation dealt only with trees as individuals, and further study of the interrelationships of groups of trees is needed.

  18. Analysis of electrical tree ageing in silicone rubber by physicochemical approach

    NASA Astrophysics Data System (ADS)

    Zhou, Y. X.; Nie, Q.; Chen, Z. Z.; Liu, R.

    2009-08-01

    In this paper, the characteristics of electrical tree ageing in silicone rubber (SIR) under AC voltage were studied. The electrical tree initiation rate is 20% after the application of 6 kV AC voltage for 1000 hours. Samples are separated into three kinds according to processes of electrical tree formation: virgin samples without voltage application, non-treed samples without electrical tree formation after 1000 hours and treed samples with electrical tree formation after 1000 hours. Certain physicochemical diagnostic tests were carried out to understand the degradation of material, ascribed to long-time voltage application, using differential scanning calorimetry (DSC) and thermogravimetric-differential thermal analysis (TG-DTA). Physicochemical analyses, especially the DSC results, show that no additional phases are formed in the processes of electrical tree ageing in SIR. Reduction of the melting point and crystallinity of SIR is observed in the sequence of virgin samples, non-treed samples and treed samples. The activation energy values were calculated from the TG-DTA data. Compared to virgin samples, obvious reduction of activation energy value is observed in non-treed samples. Degradation in SIR has already occurred before electrical tree formation and charge injection and extraction by high field electrode under AC voltage is regarded as the reason.

  19. Infiltration and water balance modeling along a toposequence in a rubber tree plantation of NE Thailand

    NASA Astrophysics Data System (ADS)

    Hammecker, Claude; Seltacho, Siwaporn; Suvanang, Nopmanee; Do, Frederic; Angulo-Jaramillo, Rafael

    2015-04-01

    Northeast of Thailand, is a plateau at 200 m AMSL with a typical undulating landscape. Traditionally the lowlands were dedicated to paddy fields and the uplands covered by Dipterocarpus forest. However development of cash crops during the last decades has led to intensive land clearing in the uplands and to modifications at a regional scale of the water balance in the critical zone with increasing runoff and soil erosion. Recent international demand increase for natural rubber motivated many local farmers to shift from these cash crops towards rubber-tree (Heva Brasiliensis) plantations. However these land use changes have been undertaken without considering the climatic and edaphic specificity of the region, which are not well adapted to the growth of rubber tree (rainfall lower than recommended and sandy soils with low fertility). Therefore, in order to assess and try to predict the environmental consequences (water resources, water-table, ..) of the development of rubber tree plantations in this area, a small watershed in the region ok Khon Kaen has been selected to follow the infiltration and to monitor the different components of the water balance along a toposequence. A six years monitoring of the main components of water balance along a toposequence associated to numerical simulation were used to quantify and try to forecast the evolution of the water use and water resources. Unsaturated soil properties were determined at different depths, in various positions along the toposequence. Experimental results supported by modeling of 2D water flow with HYDRUS3D show clearly that infiltration is blocked by a clayey layer on top of the bedrock and conditioned the occurrence of a perched watertable during the rainy seasons. Most of the soil water flow was found to be directed laterally during the rainy season. The deep groundwater was found to be fed from the lower part of toposequence in the thalweg. The transpiration rate measured on the trees at this stage of

  20. Age-dependent and jasmonic acid-induced laticifer-cell differentiation in anther callus cultures of rubber tree.

    PubMed

    Tan, Deguan; Sun, Xuepiao; Zhang, Jiaming

    2014-08-01

    Callus cultures of rubber tree may serve as an efficient model to screen and study environmental factors and phytohormones that stimulate laticifer cell differentiation and improve latex yield. The number of laticifer cells in bark is one of the most important factors determining the biosynthesis and economic value of rubber trees (Hevea brasiliensis). The differentiation of laticifer cells in planta has been characterized, whereas laticifer-cell differentiation in callus cultures in vitro is largely unknown. In this study, we present molecular and physiological evidences for laticifer-cell differentiation in calli derived from rubber tree anthers. RT-PCR analysis showed that three key genes rubber elongation factor (REF), small rubber particle protein (SRPP), and cis-prenyl transferase (CPT) that are essential in latex biosynthesis in rubber tree bark also were transcribed in anther calli. Laticifer cell development in callus cultures was age-dependent; the cells began to appear at 58 days after initiation of culture, and the percentage of laticifer cells increased steadily with increasing callus age. Addition of 0-2 mg/L jasmonic acid (JA) to the media significantly promoted the differentiation of laticifer cells in callus cultures. However, JA concentrations higher than 3 mg/L were not optimum for laticifer cells differentiation; this result was not observed in previous in planta studies. Laticifer cells differentiated on media with pH 5.8-7.0, with an optimum of pH 6.2, whereas a higher pH inhibited differentiation. These results indicate that the anther-derived rubber tree callus may serve as a new and more efficient model to study environmental factors that influence laticifer cell differentiation, and may be useful for research on new technologies to improve latex yield, and to screen for commercially useful phytohormones.

  1. Molecular identification and characterization of the pyruvate decarboxylase gene family associated with latex regeneration and stress response in rubber tree.

    PubMed

    Long, Xiangyu; He, Bin; Wang, Chuang; Fang, Yongjun; Qi, Jiyan; Tang, Chaorong

    2015-02-01

    In plants, ethanolic fermentation occurs not only under anaerobic conditions but also under aerobic conditions, and involves carbohydrate and energy metabolism. Pyruvate decarboxylase (PDC) is the first and the key enzyme of ethanolic fermentation, which branches off the main glycolytic pathway at pyruvate. Here, four PDC genes were isolated and identified in a rubber tree, and the protein sequences they encode are very similar. The expression patterns of HbPDC4 correlated well with tapping-simulated rubber productivity in virgin rubber trees, indicating it plays an important role in regulating glycometabolism during latex regeneration. HbPDC1, HbPDC2 and HbPDC3 had striking expressional responses in leaves and bark to drought, low temperature and high temperature stresses, indicating that the HbPDC genes are involve in self-protection and defense in response to various abiotic and biotic stresses during rubber tree growth and development. To understand ethanolic fermentation in rubber trees, it will be necessary to perform an in-depth study of the regulatory pathways controlling the HbPDCs in the future.

  2. A simple framework to analyze water constraints on seasonal transpiration in rubber tree (Hevea brasiliensis) plantations

    PubMed Central

    Sopharat, Jessada; Gay, Frederic; Thaler, Philippe; Sdoodee, Sayan; Isarangkool Na Ayutthaya, Supat; Tanavud, Charlchai; Hammecker, Claude; Do, Frederic C.

    2015-01-01

    Climate change and fast extension in climatically suboptimal areas threaten the sustainability of rubber tree cultivation. A simple framework based on reduction factors of potential transpiration was tested to evaluate the water constraints on seasonal transpiration in tropical sub-humid climates, according pedoclimatic conditions. We selected a representative, mature stand in a drought-prone area. Tree transpiration, evaporative demand and soil water availability were measured every day over 15 months. The results showed that basic relationships with evaporative demand, leaf area index and soil water availability were globally supported. However, the implementation of a regulation of transpiration at high evaporative demand whatever soil water availability was necessary to avoid large overestimates of transpiration. The details of regulation were confirmed by the analysis of canopy conductance response to vapor pressure deficit. The final objective of providing hierarchy between the main regulation factors of seasonal and annual transpiration was achieved. In the tested environmental conditions, the impact of atmospheric drought appeared larger importance than soil drought contrary to expectations. Our results support the interest in simple models to provide a first diagnosis of water constraints on transpiration with limited data, and to help decision making toward more sustainable rubber plantations. PMID:25610443

  3. A simple framework to analyze water constraints on seasonal transpiration in rubber tree (Hevea brasiliensis) plantations.

    PubMed

    Sopharat, Jessada; Gay, Frederic; Thaler, Philippe; Sdoodee, Sayan; Isarangkool Na Ayutthaya, Supat; Tanavud, Charlchai; Hammecker, Claude; Do, Frederic C

    2014-01-01

    Climate change and fast extension in climatically suboptimal areas threaten the sustainability of rubber tree cultivation. A simple framework based on reduction factors of potential transpiration was tested to evaluate the water constraints on seasonal transpiration in tropical sub-humid climates, according pedoclimatic conditions. We selected a representative, mature stand in a drought-prone area. Tree transpiration, evaporative demand and soil water availability were measured every day over 15 months. The results showed that basic relationships with evaporative demand, leaf area index and soil water availability were globally supported. However, the implementation of a regulation of transpiration at high evaporative demand whatever soil water availability was necessary to avoid large overestimates of transpiration. The details of regulation were confirmed by the analysis of canopy conductance response to vapor pressure deficit. The final objective of providing hierarchy between the main regulation factors of seasonal and annual transpiration was achieved. In the tested environmental conditions, the impact of atmospheric drought appeared larger importance than soil drought contrary to expectations. Our results support the interest in simple models to provide a first diagnosis of water constraints on transpiration with limited data, and to help decision making toward more sustainable rubber plantations.

  4. Wound-induced accumulation of mRNA containing a hevein sequence in laticifers of rubber tree (Hevea brasiliensis).

    PubMed Central

    Broekaert, I; Lee, H I; Kush, A; Chua, N H; Raikhel, N

    1990-01-01

    Hevein is a chitin-binding protein that is present in laticifers of the rubber tree (Hevea brasiliensis). A cDNA clone (HEV1) encoding hevein was isolated by using the polymerase chain reaction with mixed oligonucleotides corresponding to two regions of hevein as primers and a Hevea latex cDNA library as a template. HEV1 is 1018 base pairs long and includes an open reading frame of 204 amino acids. The deduced amino acid sequence contains a putative signal sequence of 17 amino acid residues followed by a 187-amino acid polypeptide. This polypeptide has two striking features. The amino-terminal region (43 amino acids) is identical to hevein and shows homology to several chitin-binding proteins and to the amino termini of wound-inducible proteins in potato and poplar. The carboxyl-terminal portion of the polypeptide (144 amino acids) is 74-79% homologous to the carboxyl-terminal region of wound-inducible genes of potato. Wounding, as well as application of the plant hormones abscisic acid and ethylene, resulted in accumulation of hevein transcripts in leaves, stems, and latex but not in roots. Images PMID:2217194

  5. Extracting distribution and expansion of rubber plantations from Landsat imagery using the C5.0 decision tree method

    NASA Astrophysics Data System (ADS)

    Sun, Zhongchang; Leinenkugel, Patrick; Guo, Huadong; Huang, Chong; Kuenzer, Claudia

    2017-04-01

    Natural tropical rainforests in China's Xishuangbanna region have undergone dramatic conversion to rubber plantations in recent decades, resulting in altering the region's environment and ecological systems. Therefore, it is of great importance for local environmental and ecological protection agencies to research the distribution and expansion of rubber plantations. The objective of this paper is to monitor dynamic changes of rubber plantations in China's Xishuangbanna region based on multitemporal Landsat images (acquired in 1989, 2000, and 2013) using a C5.0-based decision-tree method. A practical and semiautomatic data processing procedure for mapping rubber plantations was proposed. Especially, haze removal and deshadowing were proposed to perform atmospheric and topographic correction and reduce the effects of haze, shadow, and terrain. Our results showed that the atmospheric and topographic correction could improve the extraction accuracy of rubber plantations, especially in mountainous areas. The overall classification accuracies were 84.2%, 83.9%, and 86.5% for the Landsat images acquired in 1989, 2000, and 2013, respectively. This study also found that the Landsat-8 images could provide significant improvement in the ability to identify rubber plantations. The extracted maps showed the selected study area underwent rapid conversion of natural and seminatural forest to a rubber plantations from 1989 to 2013. The rubber plantation area increased from 2.8% in 1989 to 17.8% in 2013, while the forest/woodland area decreased from 75.6% in 1989 to 44.8% in 2013. The proposed data processing procedure is a promising approach to mapping the spatial distribution and temporal dynamics of rubber plantations on a regional scale.

  6. Estimation on rubber tree disturbance caused by typhoon Damery (200518) with Landsat and MODIS data in Hainan Island of China

    NASA Astrophysics Data System (ADS)

    Tan, Chenyan; Fang, Weihua; Li, Jian

    2016-04-01

    In 2005, Typhoon Damery (200518) caused severe damage to the rubber trees in Hainan Island with its destructive winds and rainfall. Selection of proper vegetation indices using multi-source remote sensing data is critical to the assessment of forest disturbance and damage loss for this event. In this study, we will compare the performance of seven vegetation indices derived from MODIS and Landsat TM imageries prior to and after typhoon Damery, in order to select an optimal index for identifying rubber tree disturbance. The indices to be compared are normalized difference vegetation index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Infrared Index (NDII), Enhanced vegetation index (EVI), Leaf area index (LAI), forest z-score (IFZ), and Disturbance Index (DI). The ground truth data of rubber tree damage collected through field investigation was used to verify and compare the results. Our preliminary result for the area with ground-truth data shows that DI has the most significant performance for disturbance detection for this typhoon event. This index DI is then applied to all the areas in Hainan Island hit by Darmey to evaluate the overall forest damage severity. At last, rubber tree damage severity is analyzed with other typhoon hazard factors such as wind, topography, soil and precipitation.

  7. Redescription of Tenuipalpus heveae Baker (Acari: Tenuipalpidae) and description of a new species collected on rubber tree from Amazonia, Brazil

    USDA-ARS?s Scientific Manuscript database

    Tenuipalpus heveae Baker, 1945 was described based only from female specimens collected on rubber trees from Belterra, State of Pará, Brazil. However, the original description does not provide essential information, and thus, it may be difficult to correctly identify the species. In this paper, we r...

  8. Impact of the timing and duration of weed control on the establishment of a rubber tree plantation.

    PubMed

    Guzzo, Caio D; Carvalho, Leonardo B de; Giancotti, Paulo R F; Alves, Pedro L C A; Gonçalves, Elaine C P; Martins, José V F

    2014-03-01

    Rubber tree production is reduced by weeds that compete for environmental resources; therefore, the timing and duration of weed control influences weed interference. The objectives of this study were to evaluate the growth of rubber tree (Hevea brasiliensis) plants, to determine the critical period for weed control, and to evaluate the growth recovery of rubber trees that coexisted with weeds for different periods of time after planting. Two groups of treatments were established under field conditions in the first year of the investigation: one group contained crescent periods of weed infestation, while the other contained crescent periods of weed control, also including a weed-free check and a total weedy check. In the second year of the investigation, the weeds were totally controlled. Urochloa decumbens was the dominant weed (over 90% groundcover). Crop growth was greatly reduced due to the weed interference. Plant height decreased more rapidly than did any other characteristic. Plant height, leaf dry mass, and leaf area decreased by 99%, 97% and 96%, respectively, and were the most reduced characteristics. Plant height also recovered more rapidly than did any characteristic when the period of weed control was lengthened. However, stem dry mass increased by 750%, making it the most recovered characteristic. The critical period for weed control was between 4 and 9½ months after planting in the first year; however, the rubber trees showed an expressive growth recovery when the weeds were controlled throughout the second year.

  9. Differential expression of microRNAs and their targets reveals a possible dual role in physiological bark disorder in rubber tree.

    PubMed

    Lertpanyasampatha, Manassawe; Viboonjun, Unchera; Kongsawadworakul, Panida; Chrestin, Hervé; Narangajavana, Jarunya

    2014-08-15

    Trunk phloem necrosis (TPN), a physiological bark disorder of the rubber tree (Hevea brasiliensis), is a serious problem that affects the yield of natural rubber. The resultant bark dryness occurs in up to half of a plantation's trees in almost every rubber tree plantation region, causing a great annual loss of dry rubber for natural rubber production. Different types of injury and physical damage caused by mechanical activation as well as environmental stresses cause physiological bark disorder in tree. Due to the essential role of miR166, miR393 and miR167 in vascular development and abiotic stress response in diverse plant species, it was interesting to investigate the role of these miRNAs in rubber trees, particularly during development of a physiological bark disorder. In this study, the expression pattern of miR166, miR393 and miR167; and their target genes, HD-ZIP III; TIR1 and ARF8, respectively; was demonstrated in healthy tree and different TPN trees. Their existence and function in vivo was validated using RNA ligase-mediated 5' rapid amplification of cDNA ends. Taken together, the results suggest a possible dual role of these three miRNAs in maintaining normal bark regeneration in healthy trees, coping with overtapping by affecting the wound healing system leading to abnormal bark regeneration in overtapped-TPN trees, and act as additional forces that enhance the attenuation of vascular development resulting in bark necrosis and cell death in the natural-TPN tree. This is the first study to address the molecular events of miRNAs involved in the physiological bark disorder TPN in rubber tree. Further study will open the possibility to better understanding of physiological and molecular perspectives during TPN development, and lead to improvement of monitoring the exploitation of rubber tree plantations. Copyright © 2014 Elsevier GmbH. All rights reserved.

  10. Genome-wide identification of rubber tree (Hevea brasiliensis Muell. Arg.) aquaporin genes and their response to ethephon stimulation in the laticifer, a rubber-producing tissue.

    PubMed

    Zou, Zhi; Gong, Jun; An, Feng; Xie, Guishui; Wang, Jikun; Mo, Yeyong; Yang, Lifu

    2015-11-25

    Natural rubber, an important industrial raw material, is specifically synthesized in laticifers located inside the rubber tree (Hevea brasiliensis Muell. Arg.) trunk. Due to the absence of plasmodesmata, the laticifer water balance is mediated by aquaporins (AQPs). However, to date, the characterization of H. brasiliensis AQPs (HbAQPs) is still in its infancy. In this study, 51 full-length AQP genes were identified from the rubber tree genome. The phylogenetic analysis assigned these AQPs to five subfamilies, including 15 plasma membrane intrinsic proteins (PIPs), 17 tonoplast intrinsic proteins (TIPs), 9 NOD26-like intrinsic proteins (NIPs), 4 small basic intrinsic proteins (SIPs) and 6 X intrinsic proteins (XIPs). Functional prediction based on the analysis of the aromatic/arginine (ar/R) selectivity filter, Froger's positions and specificity-determining positions (SDPs) showed a remarkable difference in substrate specificity among subfamilies. Homology analysis supported the expression of 44 HbAQP genes in at least one of the examined tissues. Furthermore, deep sequencing of the laticifer transcriptome in the form of latex revealed a key role of several PIP subfamily members in the laticifer water balance, and qRT-PCR analysis showed diverse expression patterns of laticifer-expressed HbAQP genes upon ethephon treatment, a widely-used practice for the stimulation of latex yield. This study provides an important genetic resource of HbAQP genes, which will be useful to improve the water use efficiency and latex yield of Hevea.

  11. Validation of reference genes for quantitative real-time PCR during latex regeneration in rubber tree.

    PubMed

    Long, Xiangyu; He, Bin; Gao, Xinsheng; Qin, Yunxia; Yang, Jianghua; Fang, Yongjun; Qi, Jiyan; Tang, Chaorong

    2015-06-01

    In rubber tree, latex regeneration is one of the decisive factors influencing the rubber yield, although its molecular regulation is not well known. Quantitative real-time PCR (qPCR) is a popular and powerful tool used to understand the molecular mechanisms of latex regeneration. However, the suitable reference genes required for qPCR are not available to investigate the expressions of target genes during latex regeneration. In this study, 20 candidate reference genes were selected and evaluated for their expression stability across the samples during the process of latex regeneration. All reference genes showed a relatively wide range of the threshold cycle values, and their stability was validated by four different algorithms (comparative delta Ct method, Bestkeeper, NormFinder and GeNorm). Three softwares (comparative delta Ct method, NormFinder and GeNorm) exported similar results that identify UBC4, ADF, UBC2a, eIF2 and ADF4 as the top five suitable references, and 18S as the least suitable one. The application of the screened references would improve accuracy and reliability of gene expression analysis in latex regeneration experiments.

  12. Expression analysis of ROS producing and scavenging enzyme-encoding genes in rubber tree infected by Pseudocercospora ulei.

    PubMed

    Koop, Daniela Martins; Rio, Maryannick; Sabau, Xavier; Almeida Cardoso, Saulo Emilio; Cazevieille, Chantal; Leclercq, Julie; Garcia, Dominique

    2016-07-01

    South American Leaf Blight (SALB), caused by the ascomycete Pseudocercospora ulei, is responsible for the low productivity of rubber trees in Latin America and is a serious threat to rubber plantations in Asia and Africa, where the rubber trees are derived from highly susceptible clones. Three contrasted genotypes were chosen for their levels of resistance to the pathogen: FX2784 (totally resistant), MDF180 (partially resistant) and PB314 (susceptible). Array analyses were previously performed to identify genes differentially expressed in resistant and susceptible genotypes. Twenty-one genes were selected for further gene expression analysis in non-inoculated and inoculated genotypes from 24 to 216 h post infection (hpi). These genes are involved in ROS production (HbRBOHA, HbRBOHB, HbRBOHC, HbRBOHD), ROS-scavenging systems (cytoplasmic and chloroplastic HbCuZnSOD, HbMnSOD, HbCAT, HbAPX1, HbAPX2, HbMDHAR, HbGCL1, HbGCL2, HbOASTL, HbGPX, HbDHAR), and leaf senescence (HbCASP, HbPCYST, HbWRKY2, HbPLY, HbKAT2). First, a genotype-dependent level of expression was observed. The genes HbRBOHA, HbCuZnSOD cyto, HbCAT, HbGCL and HbWRKY2 were constitutively expressed at lower levels in the MDF180 genotype than in the FX2784 and PB314 genotypes. Conversely, the levels of expression of HbDHAR, HbGPX and HbPCYST were higher in the older, non-inoculated leaves of MDF180. Lower production of ROS and efficient regeneration of reduced ascorbate ensure a balanced redox intracellular state in this genotype. Second, inoculation of the leaves induced few modifications in the expression level of the studied genes. In the MDF180 partially resistant genotype, an increase in the expression level of HbRBOHB, HbRBOHD 48 hpi and a decrease in the expression level of HbDHAR 216 hpi were observed. In the FX2784 totally resistant genotype, an increase in the expression level of HbRBOHD and HbCuZnSOD cyto and a decrease in HbCAT were observed 48 hpi. This transitory variation could be associated

  13. [A review of the genomic and gene cloning studies in trees].

    PubMed

    Yin, Tong-Ming

    2010-07-01

    Supported by the Department of Energy (DOE) of U.S., the first tree genome, black cottonwood (Populus trichocarpa), has been completely sequenced and publicly release. This is the milestone that indicates the beginning of post-genome era for forest trees. Identification and cloning genes underlying important traits are one of the main tasks for the post-genome-era tree genomic studies. Recently, great achievements have been made in cloning genes coordinating important domestication traits in some crops, such as rice, tomato, maize and so on. Molecular breeding has been applied in the practical breeding programs for many crops. By contrast, molecular studies in trees are lagging behind. Trees possess some characteristics that make them as difficult organisms for studying on locating and cloning of genes. With the advances in techniques, given also the fast growth of tree genomic resources, great achievements are desirable in cloning unknown genes from trees, which will facilitate tree improvement programs by means of molecular breeding. In this paper, the author reviewed the progress in tree genomic and gene cloning studies, and prospected the future achievements in order to provide a useful reference for researchers working in this area.

  14. Profiling Ethylene-Responsive Genes Expressed in the Latex of the Mature Virgin Rubber Trees Using cDNA Microarray.

    PubMed

    Nie, Zhiyi; Kang, Guijuan; Duan, Cuifang; Li, Yu; Dai, Longjun; Zeng, Rizhong

    2016-01-01

    Ethylene is commonly used as a latex stimulant of Hevea brasiliensis by application of ethephon (chloro-2-ethylphosphonic acid); however, the molecular mechanism by which ethylene increases latex production is not clear. To better understand the effects of ethylene stimulation on the laticiferous cells of rubber trees, a latex expressed sequence tag (EST)-based complementary DNA microarray containing 2,973 unique genes (probes) was first developed and used to analyze the gene expression changes in the latex of the mature virgin rubber trees after ethephon treatment at three different time-points: 8, 24 and 48 h. Transcript levels of 163 genes were significantly altered with fold-change values ≥ 2 or ≤ -2 (q-value < 0.05) in ethephon-treated rubber trees compared with control trees. Of the 163 genes, 92 were up-regulated and 71 down-regulated. The microarray results were further confirmed using real-time quantitative reverse transcript-PCR for 20 selected genes. The 163 ethylene-responsive genes were involved in several biological processes including organic substance metabolism, cellular metabolism, primary metabolism, biosynthetic process, cellular response to stimulus and stress. The presented data suggest that the laticifer water circulation, production and scavenging of reactive oxygen species, sugar metabolism, and assembly and depolymerization of the latex actin cytoskeleton might play important roles in ethylene-induced increase of latex production. The results may provide useful insights into understanding the molecular mechanism underlying the effect of ethylene on latex metabolism of H. brasiliensis.

  15. Population Dynamics of the Rubber Plantation Litter Beetle Luprops tristis, in Relation to Annual Cycle of Foliage Phenology of Its Host, the Para Rubber Tree, Hevea brasiliensis

    PubMed Central

    Sabu, Thomas K.; Vinod, K.V.

    2009-01-01

    The population dynamics of the rubber plantation litter beetle, Luprops tristis Fabricius 1801 (Coleoptera: Tenebrionidae) was assessed in relation to the phenology of leaf shedding and defoliation pattern of para rubber trees, Hevea brasiliensis Müll. Arg (Malpighiales: Euphorbiaceae), during a two year study period. The abundance of adults, larvae and pupae per 1m2 of litter sample was recorded. Post dormancy beetles appeared in leaf litter following annual leaf shedding, whereas larvae, pupae and teneral adults were present after leaf flush. No stages were recorded from plantations following the summer rains until the annual litter fall in the next season. Parental adults peaked at the time of leaf sprouting and tender leaf fall. Larvae and teneral adults peaked at the time of premature fall of green leaves and flowers. Teneral adults of six age classes were recorded and all entered dormancy irrespective of the feeding time available to each age class. Females outnumbered males in the parent generation, while the sex ratio of new generation adults was not biased towards either sex. The phenological stages of rubber trees included leaf fall in late December and early January, leaf sprouting and new leaf production in January and flowering in February. All feeding stages of L. tristis peaked in abundance when premature leaves are most abundant in the leaf litter. Prediction of the timing of appearance of various developmental stages of L. tristis in plantations, invasion into buildings and intensity of population build up in rubber belts is possible by tracking the phenology of leaf fall in rubber plantations, time of return of post dormancy adults and the onset of summer rainfall. Perfect synchrony was recorded between the field return of parental adults with annual leaf shedding, the oviposition phase of parental adults with tender leaf fall at the time of leaf sprouting, and larval and teneral adult stages with premature fall of leaves. Premature leaf

  16. Population dynamics of the rubber plantation litter beetle Luprops tristis, in relation to annual cycle of foliage phenology of its host, the para rubber tree, Hevea brasiliensis.

    PubMed

    Sabu, Thomas K; Vinod, K V

    2009-01-01

    The population dynamics of the rubber plantation litter beetle, Luprops tristis Fabricius 1801 (Coleoptera: Tenebrionidae) was assessed in relation to the phenology of leaf shedding and defoliation pattern of para rubber trees, Hevea brasiliensis Müll. Arg (Malpighiales: Euphorbiaceae), during a two year study period. The abundance of adults, larvae and pupae per 1m(2) of litter sample was recorded. Post dormancy beetles appeared in leaf litter following annual leaf shedding, whereas larvae, pupae and teneral adults were present after leaf flush. No stages were recorded from plantations following the summer rains until the annual litter fall in the next season. Parental adults peaked at the time of leaf sprouting and tender leaf fall. Larvae and teneral adults peaked at the time of premature fall of green leaves and flowers. Teneral adults of six age classes were recorded and all entered dormancy irrespective of the feeding time available to each age class. Females outnumbered males in the parent generation, while the sex ratio of new generation adults was not biased towards either sex. The phenological stages of rubber trees included leaf fall in late December and early January, leaf sprouting and new leaf production in January and flowering in February. All feeding stages of L. tristis peaked in abundance when premature leaves are most abundant in the leaf litter. Prediction of the timing of appearance of various developmental stages of L. tristis in plantations, invasion into buildings and intensity of population build up in rubber belts is possible by tracking the phenology of leaf fall in rubber plantations, time of return of post dormancy adults and the onset of summer rainfall. Perfect synchrony was recorded between the field return of parental adults with annual leaf shedding, the oviposition phase of parental adults with tender leaf fall at the time of leaf sprouting, and larval and teneral adult stages with premature fall of leaves. Premature leaf

  17. Phytoseiidae (Acari: Mesostigmata) from rubber tree crops in the State of Bahia, Brazil, with description of two new species.

    PubMed

    Nuvoloni, Felipe Micali; Lofego, Antonio Carlos; Castro, Elizeu Barbosa; Feres, Reinaldo José Fazzio

    2015-06-02

    The current study describes the results of a survey of Phytoseiidae mites conducted on a rubber tree plantation in the State of Bahia, Brazil. We present 22 species, two of which are new to science, Amblydromalus insolitus n. sp. Nuvoloni & Lofego, and Typhlodromips paramilus n. sp. Nuvoloni & Lofego, and three new records for this host are presented. The species composition was more related with the records of the northern Brazilian Region, than with that of Southeastern and Midwestern.

  18. Transcriptome sequencing and analysis of rubber tree (Hevea brasiliensis Muell.) to discover putative genes associated with tapping panel dryness (TPD).

    PubMed

    Liu, Jin-Ping; Xia, Zhi-Qiang; Tian, Xiao-Yan; Li, Yi-Jian

    2015-05-21

    Tapping panel dryness (TPD) involves in the partial or complete cessation of latex flow thus seriously affect latex production in rubber tree (Hevea brasiliensis). Numerous studies have been conducted to define its origin and nature, but the molecular nature and mechanism of TPD occurrence remains unknown. This study is committed to de novo sequencing and comparative analysis of the transcriptomes of healthy (H) and TPD-affected (T) rubber trees to identify the genes and pathways related to the TPD. Total raw reads of 34,632,012 and 35,913,020 bp were obtained from H and T library, respectively using Illumina Hiseq 2000 sequencing technology. De novo assemblies yielded 141,456 and 169,285 contigs, and 96,070 and 112,243 unigenes from H and T library, respectively. Among 73597 genes, 22577 genes were identified as differential expressed genes between H and T library via comparative transcript profiling. A majority of genes involved in natural rubber biosynthesis and jasmonate synthesis with most potential relevance in TPD occurrence were found to be differentially expressed. In TPD-affected trees, the expression of most genes related to the latex biosynthesis and jasmonate synthesis was severely inhibited and is probably the direct cause of the TPD. These new de novo transcriptome data sets provide a significant resource for the discovery of genes related to TPD and improve our understanding of the occurrence and maintainace of TPD.

  19. Depolymerization of beta-chitin to mono- and disaccharides by the serum fraction from the para rubber tree, Hevea brasiliensis.

    PubMed

    Klaikherd, Akamol; Siripastr Jayanta, M L; Boonjawat, Jariya; Aiba, Sei-ichi; Sukwattanasinitt, Mongkol

    2004-12-06

    The serum fraction of latex from Hevea brasiliensis, the para rubber tree, is known to contain an endo-chitinolytic enzyme, hevamine. Herein the activity of the rubber serum towards beta-chitin is investigated. The serum contained 6 mg/mL of protein and a chitinolytic activity of 18 mU permg of protein. The optimum ratio of enzyme to chitin was 0.22 mU/mg, and the optimum substrate concentration was 60 mg/mL. The optimum pH range was pH2-4, and the optimum temperature was 45 degrees C. At these conditions both (GlcNAc)2 and GlcNAc were produced in a molar ratio of approximately 2:1. The hydrolysis of 300 mg of chitin with 64 mU of the rubber serum for 8 days under the optimum conditions gave 39 mg of GlcNAc and 108 mg of (GlcNAc)2 as determined by HPLC. Mixing the rubber serum preparation with an Aspergillus niger pectinase preparation containing beta-N-acetylhexosaminidase can be used to produce almost exclusively the GlcNAc monomer in about 50% yield.

  20. Simulation of Canopy CO2/H2O Fluxes for a Rubber (Hevea Brasiliensis) Plantation in Central Cambodia: The Effect of the Regular Spacing of Planted Trees

    SciTech Connect

    Kumagai, Tomo'omi; Mudd, Ryan; Miyazawa, Yoshiyuki; Liu, Wen; Giambelluca, Thomas; Kobayashi, N.; Lim, Tiva Khan; Jomura, Mayuko; Matsumoto, Kazuho; Huang, Maoyi; Chen, Qi; Ziegler, Alan; Yin, Song

    2013-09-10

    We developed a soil-vegetation-atmosphere transfer (SVAT) model applicable to simulating CO2 and H2O fluxes from the canopies of rubber plantations, which are characterized by distinct canopy clumping produced by regular spacing of plantation trees. Rubber (Hevea brasiliensis Müll. Arg.) plantations, which are rapidly expanding into both climatically optimal and sub-optimal environments throughout mainland Southeast Asia, potentially change the partitioning of water, energy, and carbon at multiple scales, compared with traditional land covers it is replacing. Describing the biosphere-atmosphere exchange in rubber plantations via SVAT modeling is therefore essential to understanding the impacts on environmental processes. The regular spacing of plantation trees creates a peculiar canopy structure that is not well represented in most SVAT models, which generally assumes a non-uniform spacing of vegetation. Herein we develop a SVAT model applicable to rubber plantation and an evaluation method for its canopy structure, and examine how the peculiar canopy structure of rubber plantations affects canopy CO2 and H2O exchanges. Model results are compared with measurements collected at a field site in central Cambodia. Our findings suggest that it is crucial to account for intensive canopy clumping in order to reproduce observed rubber plantation fluxes. These results suggest a potentially optimal spacing of rubber trees to produce high productivity and water use efficiency.

  1. Transcriptome Analysis of the Signalling Networks in Coronatine-Induced Secondary Laticifer Differentiation from Vascular Cambia in Rubber Trees

    PubMed Central

    Wu, Shaohua; Zhang, Shixin; Chao, Jinquan; Deng, Xiaomin; Chen, Yueyi; Shi, Minjing; Tian, Wei-Min

    2016-01-01

    The secondary laticifer in rubber tree (Hevea brasiliensis Muell. Arg.) is a specific tissue within the secondary phloem. This tissue differentiates from the vascular cambia, and its function is natural rubber biosynthesis and storage. Given that jasmonates play a pivotal role in secondary laticifer differentiation, we established an experimental system with jasmonate (JA) mimic coronatine (COR) for studying the secondary laticifer differentiation: in this system, differentiation occurs within five days of the treatment of epicormic shoots with COR. In the present study, the experimental system was used to perform transcriptome sequencing and gene expression analysis. A total of 67,873 unigenes were assembled, and 50,548 unigenes were mapped at least in one public database. Of these being annotated unigenes, 15,780 unigenes were differentially expressed early after COR treatment, and 19,824 unigenes were differentially expressed late after COR treatment. At the early stage, 8,646 unigenes were up-regulated, while 7,134 unigenes were down-regulated. At the late stage, the numbers of up- and down-regulated unigenes were 7,711 and 12,113, respectively. The annotation data and gene expression analysis of the differentially expressed unigenes suggest that JA-mediated signalling, Ca2+ signal transduction and the CLAVATA-MAPK-WOX signalling pathway may be involved in regulating secondary laticifer differentiation in rubber trees. PMID:27808245

  2. Comparative study on the technological properties of latex and natural rubber from Hancornia speciosa Gomes and Hevea brasiliensis

    USDA-ARS?s Scientific Manuscript database

    This work reports a systematic comparative study of the properties of natural lattices and rubbers extracted from Hancornia speciosa Gomes and Hevea brasiliensis [(Willd. ex Adr. de Juss.) Muell.-Arg.] (clone RRIM 600) trees from 11 collections in Brazil throughout 2004. Natural rubber latex particl...

  3. Characterization of polypeptides accumulated in the latex cytosol of rubber trees affected by the tapping panel dryness syndrome.

    PubMed

    Sookmark, Unchera; Pujade-Renaud, Valérie; Chrestin, Hervé; Lacote, Régis; Naiyanetr, Chinda; Seguin, Marc; Romruensukharom, Phayao; Narangajavana, Jarunya

    2002-11-01

    The tapping panel dryness (TPD) syndrome of rubber is characterized by the reduction or ultimately total cessation of latex flow upon tapping, due to physiological disorders in the bark tissue. The protein pattern in the cytoplasm from healthy and TPD tree latex cells was compared by electrophoresis. Two polypeptides (P15 and P22) of 15 and 22 kDa, respectively, were found to accumulate in the cytosol of the TPD-affected trees, whereas a 29 kDa polypeptide (P29) appeared de novo. P15 and P22 were identified as REF (Hev b1) and SRPP (Hev b3), respectively, two proteins proposed to be involved in rubber biosynthesis. P29 appeared to be a new member of the patatin-like protein family. Specific molecular probes were designed for a detailed characterization of REF and SRPP gene expression and RFLP mapping. This allowed the demonstration that REF and SRPP display very similar expression profiles. They are highly over-expressed by the tapping-induced metabolic activation, although not by wounding per se, or ethylene or ABA. In addition to this similarity in gene expression, they were found to share one common locus in the genome. No significant difference in REF and SRPP gene expression was observed between healthy and TPD trees, indicating that their TPD-related accumulation in the cytosol was not transcriptionally regulated. Western blot analysis demonstrated that osmotic lysis of the sedimentable organelles (lutoids) in vitro caused the release of REF and SRPP from the rubber particle membrane into the cytosol. A mechanism of cellular delocalization as a consequence of the lutoids instability is proposed to explain REF and SRPP accumulation in the cytosol of TPD trees.

  4. Profiling Ethylene-Responsive Genes Expressed in the Latex of the Mature Virgin Rubber Trees Using cDNA Microarray

    PubMed Central

    Nie, Zhiyi; Kang, Guijuan; Duan, Cuifang; Li, Yu; Dai, Longjun; Zeng, Rizhong

    2016-01-01

    Ethylene is commonly used as a latex stimulant of Hevea brasiliensis by application of ethephon (chloro-2-ethylphosphonic acid); however, the molecular mechanism by which ethylene increases latex production is not clear. To better understand the effects of ethylene stimulation on the laticiferous cells of rubber trees, a latex expressed sequence tag (EST)-based complementary DNA microarray containing 2,973 unique genes (probes) was first developed and used to analyze the gene expression changes in the latex of the mature virgin rubber trees after ethephon treatment at three different time-points: 8, 24 and 48 h. Transcript levels of 163 genes were significantly altered with fold-change values ≥ 2 or ≤ –2 (q-value < 0.05) in ethephon-treated rubber trees compared with control trees. Of the 163 genes, 92 were up-regulated and 71 down-regulated. The microarray results were further confirmed using real-time quantitative reverse transcript-PCR for 20 selected genes. The 163 ethylene-responsive genes were involved in several biological processes including organic substance metabolism, cellular metabolism, primary metabolism, biosynthetic process, cellular response to stimulus and stress. The presented data suggest that the laticifer water circulation, production and scavenging of reactive oxygen species, sugar metabolism, and assembly and depolymerization of the latex actin cytoskeleton might play important roles in ethylene-induced increase of latex production. The results may provide useful insights into understanding the molecular mechanism underlying the effect of ethylene on latex metabolism of H. brasiliensis. PMID:26985821

  5. Identification and characterization of the abscisic acid (ABA) receptor gene family and its expression in response to hormones in the rubber tree

    PubMed Central

    Guo, Dong; Zhou, Ying; Li, Hui-Liang; Zhu, Jia-Hong; Wang, Ying; Chen, Xiong-Ting; Peng, Shi-Qing

    2017-01-01

    Abscisic acid (ABA) is an essential phytohormone involved in diverse physiological processes. Although genome-wide analyses of the ABA receptor PYR/PYL/RCAR (PYL) protein/gene family have been performed in certain plant species, little is known about the ABA receptor protein/gene family in the rubber tree (Hevea brasiliensis). In this study, we identified 14 ABA receptor PYL proteins/genes (designated HbPYL1 through HbPYL14) in the most recent rubber tree genome. A phylogenetic tree was constructed, which demonstrated that HbPYLs can be divided into three subfamilies that correlate well with the corresponding Arabidopsis subfamilies. Eight HbPYLs are highly expressed in laticifers. Five of the eight genes are simultaneously regulated by ABA, jasmonic acid (JA) and ethylene (ET). The identification and characterization of HbPYLs should enable us to further understand the role of ABA signal in the rubber tree. PMID:28332623

  6. Visualization of micromorphology of leaf epicuticular waxes of the rubber tree Ficus elastica by electron microscopy.

    PubMed

    Kim, Ki Woo

    2008-10-01

    Ultrastructural aspects of leaf epicuticular waxes were investigated in Ficus elastica by scanning and transmission electron microscopy. Glossy leaves of the rubber tree were collected and subjected to different regimes of specimen preparation for surface observations. F. elastica leaves were hypostomatic and stomata were surrounded with a cuticular thickening that formed a rim. The most prominent epicuticular wax structures of F. elastica leaves included granules and platelets. Without fixation and metal coating, epicuticular wax structures could be discerned on the leaf surface by low-vacuum (ca. 7 Pa) scanning electron microscopy. In terms of delineation and retention of the structures, the combination of vapor fixation by glutaraldehyde and osmium tetroxide with subsequent gold coating provided the most satisfactory results, as evidenced by high resolution and sharp protrusions of epicuticular waxes. However, erosion of epicuticular wax edges was noted in the immersion fixed leaves, showing less elongated platelets, less distinct wax edges, and granule cracking. These results suggest that the vapor fixation procedure for demonstrating three-dimensional epicuticular wax structures would facilitate characterization of diverse types of waxes. Instances were noted where epicuticular waxes grew over neighboring epidermal ridges and occluded stomata. In cross sections, epicuticular waxes were observed above the cuticle proper and ranged approximately from 100 nm to 500 nm in thickness. The native leaf epicuticular waxes had many layers of different electron density that were oriented parallel to each other and parallel or perpendicular to the cuticle surface, implying strata of crystal growth. Such retention of native epicuticular wax structures could be achieved through the use of acrylic resin treated with less harsh dehydrants and mild heat polymerization, alleviating wax extraction during specimen preparations.

  7. De novo assembly and characterization of bark transcriptome using Illumina sequencing and development of EST-SSR markers in rubber tree (Hevea brasiliensis Muell. Arg.)

    PubMed Central

    2012-01-01

    Background In rubber tree, bark is one of important agricultural and biological organs. However, the molecular mechanism involved in the bark formation and development in rubber tree remains largely unknown, which is at least partially due to lack of bark transcriptomic and genomic information. Therefore, it is necessary to carried out high-throughput transcriptome sequencing of rubber tree bark to generate enormous transcript sequences for the functional characterization and molecular marker development. Results In this study, more than 30 million sequencing reads were generated using Illumina paired-end sequencing technology. In total, 22,756 unigenes with an average length of 485 bp were obtained with de novo assembly. The similarity search indicated that 16,520 and 12,558 unigenes showed significant similarities to known proteins from NCBI non-redundant and Swissprot protein databases, respectively. Among these annotated unigenes, 6,867 and 5,559 unigenes were separately assigned to Gene Ontology (GO) and Clusters of Orthologous Group (COG). When 22,756 unigenes searched against the Kyoto Encyclopedia of Genes and Genomes Pathway (KEGG) database, 12,097 unigenes were assigned to 5 main categories including 123 KEGG pathways. Among the main KEGG categories, metabolism was the biggest category (9,043, 74.75%), suggesting the active metabolic processes in rubber tree bark. In addition, a total of 39,257 EST-SSRs were identified from 22,756 unigenes, and the characterizations of EST-SSRs were further analyzed in rubber tree. 110 potential marker sites were randomly selected to validate the assembly quality and develop EST-SSR markers. Among 13 Hevea germplasms, PCR success rate and polymorphism rate of 110 markers were separately 96.36% and 55.45% in this study. Conclusion By assembling and analyzing de novo transcriptome sequencing data, we reported the comprehensive functional characterization of rubber tree bark. This research generated a substantial fraction

  8. [cDNA cloning and sequence analysis of pluripotency genes in tree shrews (Tupaia belangeri)].

    PubMed

    Wang, Cai-Yun; Ma, Yun-Han; He, Da-Jian; Yang, Shi-Hua

    2013-04-01

    In this paper, partial sequences of the tree shrew (Tupaia belangeri) Klf4, Sox2, and c-Myc genes were cloned and sequenced, which were 382, 612, and 485 bp in length and encoded 127, 204, and 161 amino acids, respectively. Whereas, their cDNA sequence identities with those of human were 89%, 98%, and 89%, respectively. Their phylogenetic tree results indicated different topologies and suggested individual evolutional pathways. These results can facilitate further functional studies.

  9. Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).

    PubMed

    Kanpanon, Nicha; Kasemsap, Poonpipope; Thaler, Philippe; Kositsup, Boonthida; Gay, Frédéric; Lacote, Régis; Epron, Daniel

    2015-11-01

    Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Impact of tapping and soil water status on fine root dynamics in a rubber tree plantation in Thailand

    PubMed Central

    Chairungsee, Naruenat; Gay, Frederic; Thaler, Philippe; Kasemsap, Poonpipope; Thanisawanyangkura, Sornprach; Chantuma, Arak; Jourdan, Christophe

    2013-01-01

    Fine roots (FR) play a major role in the water and nutrient uptake of plants and contribute significantly to the carbon and nutrient cycles of ecosystems through their annual production and turnover. FR growth dynamics were studied to understand the endogenous and exogenous factors driving these processes in a 14-year-old plantation of rubber trees located in eastern Thailand. FR dynamics were observed using field rhizotrons from October 2007 to October 2009. This period covered two complete dry seasons (November to March) and two complete rainy seasons (April to October), allowing us to study the effect of rainfall seasonality on FR dynamics. Rainfall and its distribution during the two successive years showed strong differences with 1500 and 950 mm in 2008 and 2009, respectively. FR production (FRP) completely stopped during the dry seasons and resumed quickly after the first rains. During the rainy seasons, FRP and the daily root elongation rate (RER) were highly variable and exhibited strong annual variations with a total FRP of 139.8 and 40.4 mm-2 and an average RER of 0.16 and 0.12 cm day-1 in 2008 and 2009, respectively. The significant positive correlations found between FRP, RER, the appearance of new roots, and rainfall at monthly intervals revealed the impact of rainfall seasonality on FR dynamics. However, the rainfall patterns failed to explain the weekly variations of FR dynamics observed particularly during the rainy seasons. At this time step, FRP, RER, and the appearance of new FR were negatively correlated to the average soil matric potential measured at a depth of between 30 and 60 cm. In addition, our study revealed a significant negative correlation between FR dynamics and the monthly production of dry rubber. Consequently, latex harvesting might disturb carbon dynamics in the whole tree, far beyond the trunk where the tapping was performed. These results exhibit the impact of climatic conditions and tapping system in the carbon budget of

  11. Impact of tapping and soil water status on fine root dynamics in a rubber tree plantation in Thailand.

    PubMed

    Chairungsee, Naruenat; Gay, Frederic; Thaler, Philippe; Kasemsap, Poonpipope; Thanisawanyangkura, Sornprach; Chantuma, Arak; Jourdan, Christophe

    2013-01-01

    Fine roots (FR) play a major role in the water and nutrient uptake of plants and contribute significantly to the carbon and nutrient cycles of ecosystems through their annual production and turnover. FR growth dynamics were studied to understand the endogenous and exogenous factors driving these processes in a 14-year-old plantation of rubber trees located in eastern Thailand. FR dynamics were observed using field rhizotrons from October 2007 to October 2009. This period covered two complete dry seasons (November to March) and two complete rainy seasons (April to October), allowing us to study the effect of rainfall seasonality on FR dynamics. Rainfall and its distribution during the two successive years showed strong differences with 1500 and 950 mm in 2008 and 2009, respectively. FR production (FRP) completely stopped during the dry seasons and resumed quickly after the first rains. During the rainy seasons, FRP and the daily root elongation rate (RER) were highly variable and exhibited strong annual variations with a total FRP of 139.8 and 40.4 mm(-) (2) and an average RER of 0.16 and 0.12 cm day(-) (1) in 2008 and 2009, respectively. The significant positive correlations found between FRP, RER, the appearance of new roots, and rainfall at monthly intervals revealed the impact of rainfall seasonality on FR dynamics. However, the rainfall patterns failed to explain the weekly variations of FR dynamics observed particularly during the rainy seasons. At this time step, FRP, RER, and the appearance of new FR were negatively correlated to the average soil matric potential measured at a depth of between 30 and 60 cm. In addition, our study revealed a significant negative correlation between FR dynamics and the monthly production of dry rubber. Consequently, latex harvesting might disturb carbon dynamics in the whole tree, far beyond the trunk where the tapping was performed. These results exhibit the impact of climatic conditions and tapping system in the carbon

  12. Survey of the rubber tree genome reveals a high number of cysteine protease-encoding genes homologous to Arabidopsis SAG12

    PubMed Central

    Liu, Jianting; Yang, Lifu; Xie, Guishui

    2017-01-01

    Arabidopsis thaliana SAG12, a senescence-specific gene encoding a cysteine protease, is widely used as a molecular marker for the study of leaf senescence. To date, its potential orthologues have been isolated from several plant species such as Brassica napus and Nicotiana tabacum. However, little information is available in rubber tree (Hevea brasiliensis), a rubber-producing plant of the Euphorbiaceae family. This study presents the identification of SAG12-like genes from the rubber tree genome. Results showed that an unexpected high number of 17 rubber orthologues with a single intron were found, contrasting the single copy with two introns in Arabidopsis. The gene expansion was also observed in another two Euphorbiaceae plants, castor bean (Ricinus communis) and physic nut (Jatropha curcas), both of which contain 8 orthologues. In accordance with no occurrence of recent whole-genome duplication (WGD) events, most duplicates in castor and physic nut were resulted from tandem duplications. In contrast, the duplicated HbSAG12H genes were derived from tandem duplications as well as the recent WGD. Expression analysis showed that most HbSAG12H genes were lowly expressed in examined tissues except for root and male flower. Furthermore, HbSAG12H1 exhibits a strictly senescence-associated expression pattern in rubber tree leaves, and thus can be used as a marker gene for the study of senescence mechanism in Hevea. PMID:28166280

  13. Evaluation of Reference Genes for Quantitative Real-Time PCR Analysis of the Gene Expression in Laticifers on the Basis of Latex Flow in Rubber Tree (Hevea brasiliensis Muell. Arg.).

    PubMed

    Chao, Jinquan; Yang, Shuguang; Chen, Yueyi; Tian, Wei-Min

    2016-01-01

    Latex exploitation-caused latex flow is effective in enhancing latex regeneration in laticifer cells of rubber tree. It should be suitable for screening appropriate reference gene for analysis of the expression of latex regeneration-related genes by quantitative real-time PCR (qRT-PCR). In the present study, the expression stability of 23 candidate reference genes was evaluated on the basis of latex flow by using geNorm and NormFinder algorithms. Ubiquitin-protein ligase 2a (UBC2a) and ubiquitin-protein ligase 2b (UBC2b) were the two most stable genes among the selected candidate references in rubber tree clones with differential duration of latex flow. The two genes were also high-ranked in previous reference gene screening across different tissues and experimental conditions. By contrast, the transcripts of latex regeneration-related genes fluctuated significantly during latex flow. The results suggest that screening reference gene during latex flow should be an efficient and effective clue for selection of reference genes in qRT-PCR.

  14. Evaluation of Reference Genes for Quantitative Real-Time PCR Analysis of the Gene Expression in Laticifers on the Basis of Latex Flow in Rubber Tree (Hevea brasiliensis Muell. Arg.)

    PubMed Central

    Chao, Jinquan; Yang, Shuguang; Chen, Yueyi; Tian, Wei-Min

    2016-01-01

    Latex exploitation-caused latex flow is effective in enhancing latex regeneration in laticifer cells of rubber tree. It should be suitable for screening appropriate reference gene for analysis of the expression of latex regeneration-related genes by quantitative real-time PCR (qRT-PCR). In the present study, the expression stability of 23 candidate reference genes was evaluated on the basis of latex flow by using geNorm and NormFinder algorithms. Ubiquitin-protein ligase 2a (UBC2a) and ubiquitin-protein ligase 2b (UBC2b) were the two most stable genes among the selected candidate references in rubber tree clones with differential duration of latex flow. The two genes were also high-ranked in previous reference gene screening across different tissues and experimental conditions. By contrast, the transcripts of latex regeneration-related genes fluctuated significantly during latex flow. The results suggest that screening reference gene during latex flow should be an efficient and effective clue for selection of reference genes in qRT-PCR. PMID:27524995

  15. Damage and loss assessment on rubber trees caused by typhoon based on high-precision remote sensing data and field investigation

    NASA Astrophysics Data System (ADS)

    Li, Jian; Fang, Weihua; Tan, Chenyan

    2016-04-01

    Forest dynamics are highly relevant to land hydrology, climate, carbon budget and biodiversity. Damage and loss assessment of forest caused by typhoon is essential to the understanding of ecosystem variations. Combination of high-precision remote sensing data and field investigation is critical to the assessment of forest damage loss. In this study, high-precision remote sensing data prior to and after typhoon from IKONOS, QuickBird, unmanned aerial vehicle (UAV) are used for identifying rubber tree disturbance. The ground truth data of rubber tree damage collected through field investigation are used to verify and compare the results. Taken the forest damage induced by typhoon Rammasun (201409) in Hainan as an example, 5 damage types (overthrown, trunk snapped below 2m, trunk snapped above 2m, half-overthrown, and sheared) of rubber trees are clearly interpreted compared with field investigation results. High-precision remote sensing data is then applied to other areas to evaluate the forest damage severity. At last, rubber tree damage severity is investigated with other typhoon hazard factors such as wind, topography, soil and precipitation.

  16. WET AND DRY SEASON ECOSYSTEM LEVEL FLUXES OF ISOPRENE AND MONOTERPENES FROM A SOUTHEAST ASIAN SECONDARY FOREST AND RUBBER TREE PLANTATION

    EPA Science Inventory

    Canopy scale fluxes of isoprene and monoterpenes were investigated in both wet and dry seasons above a rubber tree (Hevea brasiliensis)/secondary tropical forest in the Yunnan province of southwestern China. Drought conditions were unusually high during the dry season experiment....

  17. WET AND DRY SEASON ECOSYSTEM LEVEL FLUXES OF ISOPRENE AND MONOTERPENES FROM A SOUTHEAST ASIAN SECONDARY FOREST AND RUBBER TREE PLANTATION

    EPA Science Inventory

    Canopy scale fluxes of isoprene and monoterpenes were investigated in both wet and dry seasons above a rubber tree (Hevea brasiliensis)/secondary tropical forest in the Yunnan province of southwestern China. Drought conditions were unusually high during the dry season experiment....

  18. Molecular identification and characterization of a gene associated with the onset of tapping panel dryness (TPD) syndrome in rubber tree (Hevea brasiliensis Muell.) by mRNA differential display.

    PubMed

    Venkatachalam, Perumal; Thulaseedharan, Arjunan; Raghothama, Kashchandra

    2009-01-01

    In rubber tree (Hevea brasiliensis), tapping panel dryness (TPD) syndrome is considered as a complex physiological disorder which affects latex biosynthesis. To identify differentially expressed genes between healthy and TPD-affected trees, mRNA differential display reverse transcriptase polymerase chain reaction (DDRT-PCR) analysis was performed. We isolated 10 differentially expressed cDNA fragments of which one cDNA encoding a putative TOM20 like protein was identified. The cDNA (1,024 bp), corresponding to the HbTOM20 gene (H evea b rasiliensis Translocase of the Outer Mitochondrial Membrane), contained an open reading frame to code for 202 amino acid protein with a theoretical pI value of 9.5 and the calculated protein M (W) was 23.5 kDa. The predicted amino acid sequence contained conserved domains of TOM20 like proteins in the N-terminal. The protein HbTOM20 has 32% and 27% similarity to Populus TOM20 and Solanum TOM20, respectively. Both semi-quantitative RT-PCR and Northern blot results revealed that the HbTOM20 expression was significantly down-regulated in TPD-affected trees compared to healthy one. Accumulation of HbTOM20 mRNA transcripts was significantly higher in the bark tissues collected from healthy region than that of partially affected by TPD (partially dried) while barely detectable in completely TPD-affected area. Differential expression pattern was noticed in three rubber clones representing various degrees of TPD tolerance. These results suggest that down-regulation of HbTOM20 in TPD-affected trees may play an important role in alteration of mitochondrial metabolism resulting in impaired latex biosynthesis.

  19. Isolation of stress-related genes of rubber particles and latex in fig tree (Ficus carica) and their expressions by abiotic stress or plant hormone treatments.

    PubMed

    Kim, Jin Sun; Kim, Yeon Ok; Ryu, Hyun Ju; Kwak, Yeon Sig; Lee, Ji Yeon; Kang, Hunseung

    2003-04-01

    Two rubber particle protein genes and one latex gene in fig tree (Ficus carica) have been isolated and their expression following various abiotic stress treatments have been investigated. The two major proteins that are tightly associated with the catalytically active rubber particles have been sequenced to be peroxidase (POX) and trypsin inhibitor (TRI). A cDNA encoding a basic class I chitinase (CHI) has also been isolated from the fig tree latex. Wounding treatment strongly induced the expression of the three stress-related genes. Among the abiotic stresses investigated, drought treatment greatly induced the expression of POX, whereas the expression of CHI and TRI decreased after the same treatment. Cold treatment reduced slightly the transcript levels of the thee genes, and NaCl reduced marginally the expression of CHI. The expression of POX, CHI, and TRI was induced by jasmonic acid and abscisic acid, by jasmonic acid, and by salicylic acid, respectively. Different expression of the stress-related genes following various abiotic stress or plant hormone treatments suggests that a crosstalk exists between the signal transduction pathways elicited by abiotic stresses and hormones in plants. Our present results showing the expression of stress-related proteins on the surface of rubber particles and latex in F. carica also imply the possible role of rubber particles and latex in defense in rubber-producing plant species.

  20. Construction of a high-density integrated genetic linkage map of rubber tree (Hevea brasiliensis) using genotyping-by-sequencing (GBS).

    PubMed

    Pootakham, Wirulda; Ruang-Areerate, Panthita; Jomchai, Nukoon; Sonthirod, Chutima; Sangsrakru, Duangjai; Yoocha, Thippawan; Theerawattanasuk, Kanikar; Nirapathpongporn, Kanlaya; Romruensukharom, Phayao; Tragoonrung, Somvong; Tangphatsornruang, Sithichoke

    2015-01-01

    Construction of linkage maps is crucial for genetic studies and marker-assisted breeding programs. Recent advances in next generation sequencing technologies allow for the generation of high-density linkage maps, especially in non-model species lacking extensive genomic resources. Here, we constructed a high-density integrated genetic linkage map of rubber tree (Hevea brasiliensis), the sole commercial producer of high-quality natural rubber. We applied a genotyping-by-sequencing (GBS) technique to simultaneously discover and genotype single nucleotide polymorphism (SNP) markers in two rubber tree populations. A total of 21,353 single nucleotide substitutions were identified, 55% of which represented transition events. GBS-based genetic maps of populations P and C comprised 1704 and 1719 markers and encompassed 2041 cM and 1874 cM, respectively. The average marker densities of these two maps were one SNP in 1.23-1.25 cM. A total of 1114 shared SNP markers were used to merge the two component maps. An integrated linkage map consisted of 2321 markers and spanned the cumulative length of 2052 cM. The composite map showed a substantial improvement in marker density, with one SNP marker in every 0.89 cM. To our knowledge, this is the most saturated genetic map in rubber tree to date. This integrated map allowed us to anchor 28,965 contigs, covering 135 Mb or 12% of the published rubber tree genome. We demonstrated that GBS is a robust and cost-effective approach for generating a common set of genome-wide SNP data suitable for constructing integrated linkage maps from multiple populations in a highly heterozygous agricultural species.

  1. Construction of a high-density integrated genetic linkage map of rubber tree (Hevea brasiliensis) using genotyping-by-sequencing (GBS)

    PubMed Central

    Pootakham, Wirulda; Ruang-Areerate, Panthita; Jomchai, Nukoon; Sonthirod, Chutima; Sangsrakru, Duangjai; Yoocha, Thippawan; Theerawattanasuk, Kanikar; Nirapathpongporn, Kanlaya; Romruensukharom, Phayao; Tragoonrung, Somvong; Tangphatsornruang, Sithichoke

    2015-01-01

    Construction of linkage maps is crucial for genetic studies and marker-assisted breeding programs. Recent advances in next generation sequencing technologies allow for the generation of high-density linkage maps, especially in non-model species lacking extensive genomic resources. Here, we constructed a high-density integrated genetic linkage map of rubber tree (Hevea brasiliensis), the sole commercial producer of high-quality natural rubber. We applied a genotyping-by-sequencing (GBS) technique to simultaneously discover and genotype single nucleotide polymorphism (SNP) markers in two rubber tree populations. A total of 21,353 single nucleotide substitutions were identified, 55% of which represented transition events. GBS-based genetic maps of populations P and C comprised 1704 and 1719 markers and encompassed 2041 cM and 1874 cM, respectively. The average marker densities of these two maps were one SNP in 1.23–1.25 cM. A total of 1114 shared SNP markers were used to merge the two component maps. An integrated linkage map consisted of 2321 markers and spanned the cumulative length of 2052 cM. The composite map showed a substantial improvement in marker density, with one SNP marker in every 0.89 cM. To our knowledge, this is the most saturated genetic map in rubber tree to date. This integrated map allowed us to anchor 28,965 contigs, covering 135 Mb or 12% of the published rubber tree genome. We demonstrated that GBS is a robust and cost-effective approach for generating a common set of genome-wide SNP data suitable for constructing integrated linkage maps from multiple populations in a highly heterozygous agricultural species. PMID:26074933

  2. Cloning

    MedlinePlus

    Cloning describes the processes used to create an exact genetic replica of another cell, tissue or organism. ... named Dolly. There are three different types of cloning: Gene cloning, which creates copies of genes or ...

  3. Cloning and characterization of a novel apolipoprotein gene, apolipoprotein AV, in tree shrews.

    PubMed

    Li, Guoping; Luo, Huairong; Sun, Guotao; Wu, Guisheng; Wu, Gang; Wang, Yan; Man, Yong; Wang, Shu; Li, Jian; Chen, Baosheng

    2013-09-01

    Apolipoprotein AV (apoAV) modulates plasma triglyceride levels, which is an independent risk factor for cardiovascular disease. ApoAV is also involved in atherosclerosis lesion formation. In order to systematically evaluate the apolipoprotein-related gene profile in tree shrew, a model for its insusceptibility to atherosclerosis, we performed apoAV cloning and characterization. The full-length cDNA of apoAV was identified using SMART-RACE. ApoAV cDNA sequence revealed two transcripts, 1,948 and 1,397 base pairs, due to alternative polyadenylation. These two transcripts share the same open reading frame (ORF), which encodes a 369-amino acid protein with high identity to human apoAV (75 %), including a 23-amino acid N-terminal signal peptide. ApoAV is expressed exclusively in the liver. Mature apoAV was expressed in E. coli BL21(DE3) and purified by Ni-chelated resin. Lipoprotein lipase activity was significantly stimulated by this recombinant protein. The full-length ORF of apoAV was cloned into pDsRed-monomer-N1 vector with a red fluorescent protein tag and was primarily localized in cytoplasm of hepG2 cells. The successful cloning, expression and localization of apoAV in tree shrew has laid down the foundation for further investigation on its structure and functions.

  4. Chloride-ion stimulation of the tonoplast H+-translocating ATPase from Hevea brasiliensis (rubber tree) latex. A dual mechanism.

    PubMed Central

    Marin, B P; Gidrol, X

    1985-01-01

    The effect of Cl- and other anions on the tonoplast H+-translocating ATPase (H+-ATPase) from Hevea brasiliensis (rubber tree) latex was investigated. Cl- and other anions stimulated the ATPase activity of tightly sealed vesicles prepared from Hevea tonoplast, with the following decreasing order of effectiveness: Cl- greater than Br- greater than SO4(2-) greater than NO3-. As indicated by the changes of the protonmotive potential difference, anion stimulation of tonoplast H+-ATPase was caused in part by the ability of these anions to dissipate the electrical potential. This interpretation assumes not a channelling of these anions against a membrane potential, negative-inside, but a modification of the permeability of these ions through the tonoplast membrane. In addition, Cl- and the other anions stimulated the ATPase activity solubilized from the tonoplast membrane. Consequently, the tonoplast H+-pumping ATPase can be considered as an anion-stimulated enzyme. These results are discussed in relation to various models described in the literature for the microsomal H+-ATPase systems claimed as tonoplast entities. PMID:2579642

  5. South American Leaf Blight of the Rubber Tree (Hevea spp.): New Steps in Plant Domestication using Physiological Features and Molecular Markers

    PubMed Central

    Lieberei, Reinhard

    2007-01-01

    Background Rubber trees (Hevea spp.) are perennial crops of Amazonian origin that have been spread over the whole tropical belt to guarantee worldwide production of natural rubber. This crop plant has found its place in many national economies of producing countries, and although its domestication by selection of suitable genotypes was very slow, it contributes a lot to the welfare of small farmers worldwide. Its development is limited by severe diseases. In South America, the main fungal disease of rubber trees is the South American leaf blight (SALB) caused by the ascomycete Microcyclus ulei. This fungus inhibits natural rubber production on a commercial scale in South and Central America. Scope The disease is still restricted to its continent of origin, but its potential to be distributed around the world rises with every transcontinental airline connection that directly links tropical regions. The need to develop control measures against the disease is an urgent task and must be carried out on an international scale. All control efforts so far taken since 1910 have ended in a miserable failure. Even the use of modern systemic fungicides and use of greatly improved application techniques have failed to prevent large losses and dieback of trees. The results of research dealing with both the disease and the pathosystem over more than 50 years are summarized and placed into perspective. Future Prospects A detailed knowledge of this host–pathogen combination requires understanding of the dynamics of Hevea leaf development, the biochemical potential for cyanide liberation, and molecular data for several types of resistance factors. Resolution of the Hevea–SALB problem may serve as a model for future host–pathogen studies of perennial plants requiring a holistic approach. PMID:17650512

  6. South American leaf blight of the rubber tree (Hevea spp.): new steps in plant domestication using physiological features and molecular markers.

    PubMed

    Lieberei, Reinhard

    2007-12-01

    Rubber trees (Hevea spp.) are perennial crops of Amazonian origin that have been spread over the whole tropical belt to guarantee worldwide production of natural rubber. This crop plant has found its place in many national economies of producing countries, and although its domestication by selection of suitable genotypes was very slow, it contributes a lot to the welfare of small farmers worldwide. Its development is limited by severe diseases. In South America, the main fungal disease of rubber trees is the South American leaf blight (SALB) caused by the ascomycete Microcyclus ulei. This fungus inhibits natural rubber production on a commercial scale in South and Central America. The disease is still restricted to its continent of origin, but its potential to be distributed around the world rises with every transcontinental airline connection that directly links tropical regions. The need to develop control measures against the disease is an urgent task and must be carried out on an international scale. All control efforts so far taken since 1910 have ended in a miserable failure. Even the use of modern systemic fungicides and use of greatly improved application techniques have failed to prevent large losses and dieback of trees. The results of research dealing with both the disease and the pathosystem over more than 50 years are summarized and placed into perspective. A detailed knowledge of this host-pathogen combination requires understanding of the dynamics of Hevea leaf development, the biochemical potential for cyanide liberation, and molecular data for several types of resistance factors. Resolution of the Hevea-SALB problem may serve as a model for future host-pathogen studies of perennial plants requiring a holistic approach.

  7. Genetic divergence of rubber tree estimated by multivariate techniques and microsatellite markers

    PubMed Central

    2010-01-01

    Genetic diversity of 60 Hevea genotypes, consisting of Asiatic, Amazonian, African and IAC clones, and pertaining to the genetic breeding program of the Agronomic Institute (IAC), Brazil, was estimated. Analyses were based on phenotypic multivariate parameters and microsatellites. Five agronomic descriptors were employed in multivariate procedures, such as Standard Euclidian Distance, Tocher clustering and principal component analysis. Genetic variability among the genotypes was estimated with 68 selected polymorphic SSRs, by way of Modified Rogers Genetic Distance and UPGMA clustering. Structure software in a Bayesian approach was used in discriminating among groups. Genetic diversity was estimated through Nei's statistics. The genotypes were clustered into 12 groups according to the Tocher method, while the molecular analysis identified six groups. In the phenotypic and microsatellite analyses, the Amazonian and IAC genotypes were distributed in several groups, whereas the Asiatic were in only a few. Observed heterozygosity ranged from 0.05 to 0.96. Both high total diversity (HT' = 0.58) and high gene differentiation (G st' = 0.61) were observed, and indicated high genetic variation among the 60 genotypes, which may be useful for breeding programs. The analyzed agronomic parameters and SSRs markers were effective in assessing genetic diversity among Hevea genotypes, besides proving to be useful for characterizing genetic variability. PMID:21637487

  8. Identification, Functional Study, and Promoter Analysis of HbMFT1, a Homolog of MFT from Rubber Tree (Hevea brasiliensis)

    PubMed Central

    Bi, Zhenghong; Li, Xiang; Huang, Huasun; Hua, Yuwei

    2016-01-01

    A homolog of MOTHER OF FT AND TFL1 (MFT) was isolated from Hevea brasiliensis and its biological function was investigated. Protein multiple sequence alignment and phylogenetic analysis revealed that HbMFT1 conserved critical amino acid residues to distinguish MFT, FLOWERING LOCUS T (FT) and TERMINAL FLOWER1 (TFL1)-like proteins and showed a closer genetic relationship to the MFT-like group. The accumulation of HbMFT1 was generally detected in various tissues except pericarps, with the highest expression in embryos and relatively higher expression in roots and stems of seedlings, flowering inflorescences, and male and female flowers. HbMFT1 putative promoter analysis showed that tissue-specific, environmental change responsive and hormone-signaling responsive elements were generally present. HbMFT1 was strongly induced under a short-day condition at 28 °C, with the highest expression after the onset of a day. Overexpression of HbMFT1 inhibited seed germination, seedling growth, and flowering in transgenic Arabidopsis. The qRT-PCR further confirmed that APETALA1 (AP1) and FRUITFULL (FUL) were drastically down-regulated in 35S::HbMFT1 plants. A histochemical β-glucuronidase (GUS) assay showed that HbMFT1::GUS activity was mainly detected in stamens and mature seeds coinciding with its original expression and notably induced in rosette leaves and seedlings of transgenic Arabidopsis by exogenous abscisic acid (ABA) due to the presence of ABA cis-elements in HbMFT1 promoter. These results suggested that HbMFT1 was mainly involved in maintenance of seed maturation and stamen development, but negatively controlled germination, growth and development of seedlings and flowering. In addition, the HbMFT1 promoter can be utilized in controlling transgene expression in stamens and seeds of rubber tree or other plant species. PMID:26950112

  9. Synthesis, Characterization, and Catalytic Activity of Sulfonated Carbon-Based Catalysts Derived From Rubber Tree Leaves and Pulp and Paper Mill Waste

    NASA Astrophysics Data System (ADS)

    Janaun, J.; Sinin, E.; Hiew, S. F.; Kong, A. M. T.; Lahin, F. A.

    2016-06-01

    Sulfonated carbon-based catalysts derived from rubber tree leaves, and pulp and paper mill waste were synthesized and characterized. Three types of catalyst synthesized were sulfonated rubber tree leaves (S-RTL), pyrolysed sludge char (P-SC) and sulfonated sludge char (S-SC). Sulfonated rubber tree leaves (S-RTL) and sulfonated sludge char (S-SC) were prepared through pyrolysis followed by functionalization via sulfonation process whereas, P- SC was only pyrolyzed without sulfonation. The characterization results indicated sulfonic acids, hydroxyl, and carboxyl moieties were detected in S-RTL and S-SC, but no sulfonic acid was detected in P-SC. Total acidity test showed S-RTL had the highest value followed by S-SC and P-SC. The thermal stability of S-RTL and S-SC were up to 230oC as the loss was associated with the decomposition of sulfonic acid group, whereas, P-SC showed higher stability than the S-RTL and S-SC. Morphology analysis showed that S-RTL consisted of an amorphous carbon structure, and a crystalline structure for P-SC and S-SC. Furthermore, traces of metal components were also detected on all of the catalysts. The catalyst catalytic activity was tested through esterification of oleic acid with methanol. The results showed that the reaction using S-RTL catalyst produced the highest conversion (99.9%) followed by P-SC (88.4%) and lastly S-SC (82.7%). The synthesized catalysts showed high potential to be used in biodiesel production.

  10. Cloning

    MedlinePlus

    ... 2001, researchers produced the first clone of an endangered species: a type of Asian ox known as a ... few days after its birth. In 2003, another endangered type of ox, called the ... many species that would otherwise disappear, others argue that cloning ...

  11. Applications of volatile compounds acquired from Muscodor heveae against white root rot disease in rubber trees (Hevea brasiliensis Müll. Arg.) and relevant allelopathy effects.

    PubMed

    Siri-Udom, Sakuntala; Suwannarach, Nakarin; Lumyong, Saisamorn

    The bioactive compounds of the volatile metabolite-producing endophytic fungus, Muscodor heveae, were examined by the process of biofumigation for the purposes of controlling white root rot disease in rubber trees (Hevea brasiliensis Müll. Arg.). Volatile organic compounds (VOCs) of M. heveae possess antimicrobial activity against Rigidoporus microporus in vitro with 100 % growth inhibition. The synthetic volatile compounds test confirmed that the major component, 3-methylbutan-1-ol, and the minor compounds, 3-methylbutyl acetate and 2-methylpropanoic acid, inhibited root and shoot growth in the tested plants 3-methylbutan-1-ol showed ED50 value and MIQ value on seed germination of ruzi grass, Arabidopsis thaliana Col-0 and tomato at 10, 5 and 5 μL(-1) airspace, respectively. In vivo tests were carried out under greenhouse conditions using M. heveae inoculum fumigated soil that had been inoculated with R. microporus inoculum. After which, all seven treatments were compared. Significant differences were observed with a disease score at 150 d after treatment. Biofumigation by M. heveae showed great suppression of the disease. Biocontrol treatments; RMH40 (40 g kg(-1)M. heveae inoculum) and RMH80 (80 g kg(-1)M. heveae inoculum) were not found to be significantly different when compared with fungicide treatment (RT) and the non-infected control, but results were found to be significantly different from R. microporus infested (R) treatment. RMH40 and RMH80 revealed a low disease scores with a high survival rate of rubber tree seedling at 100 %, while R treatment showed the highest disease score of 4.8 ± 0.5 with a survival rate of rubber tree seedling at 25 %. The infected roots, appearing as a white colour. We have concluded that the bioactive VOCs of M. heveae would be an alternative method for the control of white root rot disease in rubber trees. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  12. Leaf-, panel- and latex-expressed sequenced tags from the rubber tree (Hevea brasiliensis) under cold-stressed and suboptimal growing conditions: the development of gene-targeted functional markers for stress response.

    PubMed

    Silva, Carla C; Mantello, Camila C; Campos, Tatiana; Souza, Livia M; Gonçalves, Paulo S; Souza, Anete P

    2014-01-01

    Hevea brasiliensis is a native species of the Amazon Basin of South America and the primary source of natural rubber worldwide. Due to the occurrence of South American Leaf Blight disease in this area, rubber plantations have been extended to suboptimal regions. Rubber tree breeding is time-consuming and expensive, but molecular markers can serve as a tool for early evaluation, thus reducing time and costs. In this work, we constructed six different cDNA libraries with the aim of developing gene-targeted molecular markers for the rubber tree. A total of 8,263 reads were assembled, generating 5,025 unigenes that were analyzed; 912 expressed sequence tags (ESTs) represented new transcripts, and two sequences were highly up-regulated by cold stress. These unigenes were scanned for microsatellite (SSR) regions and single nucleotide polymorphisms (SNPs). In total, 169 novel EST-SSR markers were developed; 138 loci were polymorphic in the rubber tree, and 98 % presented transferability to six other Hevea species. Locus duplication was observed in H. brasiliensis and other species. Additionally, 43 SNP markers in 13 sequences that showed similarity to proteins involved in stress response, latex biosynthesis and developmental processes were characterized. cDNA libraries are a rich source of SSR and SNP markers and enable the identification of new transcripts. The new markers developed here will be a valuable resource for linkage mapping, QTL identification and other studies in the rubber tree and can also be used to evaluate the genetic variability of other Hevea species, which are valuable assets in rubber tree breeding.

  13. Ethylene stimulation of latex yield depends on the expression of a sucrose transporter (HbSUT1B) in rubber tree (Hevea brasiliensis).

    PubMed

    Dusotoit-Coucaud, Anaïs; Kongsawadworakul, Panida; Maurousset, Laurence; Viboonjun, Unshira; Brunel, Nicole; Pujade-Renaud, Valérie; Chrestin, Hervé; Sakr, Soulaïman

    2010-12-01

    Hevea brasiliensis is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and requires sucrose as the unique precursor. Ethylene stimulation of latex production results in high sugar flow from the surrounding cells of inner bark towards the latex cells. The aim of this work was to understand the role of seven sucrose transporters (HbSUTs) and one hexose transporter (HbHXT1) in this process. Two Hevea clones were used: PB217 and PB260, respectively described as high and low yielding clones. The expression pattern of these sugar transporters (HbSUTs and HbHXT1) was monitored under different physiological conditions and found to be maximal in latex cells. HbSUT1, one of the most abundant isoforms, displayed the greatest response to ethylene treatment. In clone PB217, ethylene treatment led to a higher accumulation of HbSUT1B in latex cells than in the inner bark tissues. Conversely, stronger expression of HbSUT1B was observed in inner bark tissues than in latex cells of PB260. A positive correlation with HbSUT1B transcript accumulation and increased latex production was further supported by its lower expression in latex cells of the virgin clone PB217.

  14. [Analysis of the molecular characteristics and cloning of full-length coding sequence of interleukin-2 in tree shrews].

    PubMed

    Huang, Xiao-Yan; Li, Ming-Li; Xu, Juan; Gao, Yue-Dong; Wang, Wen-Guang; Yin, An-Guo; Li, Xiao-Fei; Sun, Xiao-Mei; Xia, Xue-Shan; Dai, Jie-Jie

    2013-04-01

    While the tree shrew (Tupaia belangeri chinensis) is an excellent animal model for studying the mechanisms of human diseases, but few studies examine interleukin-2 (IL-2), an important immune factor in disease model evaluation. In this study, a 465 bp of the full-length IL-2 cDNA encoding sequence was cloned from the RNA of tree shrew spleen lymphocytes, which were then cultivated and stimulated with ConA (concanavalin). Clustal W 2.0 was used to compare and analyze the sequence and molecular characteristics, and establish the similarity of the overall structure of IL-2 between tree shrews and other mammals. The homology of the IL-2 nucleotide sequence between tree shrews and humans was 93%, and the amino acid homology was 80%. The phylogenetic tree results, derived through the Neighbour-Joining method using MEGA5.0, indicated a close genetic relationship between tree shrews, Homo sapiens, and Macaca mulatta. The three-dimensional structure analysis showed that the surface charges in most regions of tree shrew IL-2 were similar to between tree shrews and humans; however, the N-glycosylation sites and local structures were different, which may affect antibody binding. These results provide a fundamental basis for the future study of IL-2 monoclonal antibody in tree shrews, thereby improving their utility as a model.

  15. Tough Rubber.

    ERIC Educational Resources Information Center

    Schmid, Sue

    1994-01-01

    Describes the benefits of using rubber floor coverings in a gym's free-weight and cardiovascular equipment areas. Tips on purchasing a rubber floor are highlighted as is an annotated list of suppliers and their rubber flooring products. (GR)

  16. Tough Rubber.

    ERIC Educational Resources Information Center

    Schmid, Sue

    1994-01-01

    Describes the benefits of using rubber floor coverings in a gym's free-weight and cardiovascular equipment areas. Tips on purchasing a rubber floor are highlighted as is an annotated list of suppliers and their rubber flooring products. (GR)

  17. Design of experiments on 135 cloned poplar trees to map environmental influence in greenhouse.

    PubMed

    Pinto, Rui Climaco; Stenlund, Hans; Hertzberg, Magnus; Lundstedt, Torbjörn; Johansson, Erik; Trygg, Johan

    2011-01-31

    To find and ascertain phenotypic differences, minimal variation between biological replicates is always desired. Variation between the replicates can originate from genetic transformation but also from environmental effects in the greenhouse. Design of experiments (DoE) has been used in field trials for many years and proven its value but is underused within functional genomics including greenhouse experiments. We propose a strategy to estimate the effect of environmental factors with the ultimate goal of minimizing variation between biological replicates, based on DoE. DoE can be analyzed in many ways. We present a graphical solution together with solutions based on classical statistics as well as the newly developed OPLS methodology. In this study, we used DoE to evaluate the influence of plant specific factors (plant size, shoot type, plant quality, and amount of fertilizer) and rotation of plant positions on height and section area of 135 cloned wild type poplar trees grown in the greenhouse. Statistical analysis revealed that plant position was the main contributor to variability among biological replicates and applying a plant rotation scheme could reduce this variation.

  18. [Cloning of full-length coding sequence of tree shrew CD4 and prediction of its molecular characteristics].

    PubMed

    Tian, Wei-Wei; Gao, Yue-Dong; Guo, Yan; Huang, Jing-Fei; Xiao, Chang; Li, Zuo-Sheng; Zhang, Hua-Tang

    2012-02-01

    The tree shrews, as an ideal animal model receiving extensive attentions to human disease research, demands essential research tools, in particular cellular markers and monoclonal antibodies for immunological studies. In this paper, a 1 365 bp of the full-length CD4 cDNA encoding sequence was cloned from total RNA in peripheral blood of tree shrews, the sequence completes two unknown fragment gaps of tree shrews predicted CD4 cDNA in the GenBank database, and its molecular characteristics were analyzed compared with other mammals by using biology software such as Clustal W2.0 and so forth. The results showed that the extracellular and intracellular domains of tree shrews CD4 amino acid sequence are conserved. The tree shrews CD4 amino acid sequence showed a close genetic relationship with Homo sapiens and Macaca mulatta. Most regions of the tree shrews CD4 molecule surface showed positive charges as humans. However, compared with CD4 extracellular domain D1 of human, CD4 D1 surface of tree shrews showed more negative charges, and more two N-glycosylation sites, which may affect antibody binding. This study provides a theoretical basis for the preparation and functional studies of CD4 monoclonal antibody.

  19. The cyanogenic syndrome in rubber tree Hevea brasiliensis: tissue-damage-dependent activation of linamarase and hydroxynitrile lyase accelerates hydrogen cyanide release

    PubMed Central

    Kadow, Daniel; Voß, Karsten; Selmar, Dirk; Lieberei, Reinhard

    2012-01-01

    Background and Aims The release of hydrogen cyanide (HCN) from injured plant tissue affects multiple ecological interactions. Plant-derived HCN can act as a defence against herbivores and also plays an important role in plant–pathogen interactions. Crucial for activity as a feeding deterrent is the amount of HCN generated per unit time, referred to as cyanogenic capacity (HCNc). Strong intraspecific variation in HCNc has been observed among cyanogenic plants. This variation, in addition to genotypic variability (e.g. in Trifolium repens), can result from modifications in the expression level of the enzymes involved in either cyanogenic precursor formation or HCN release (as seen in Sorghum bicolor and Phaseolus lunatus). Thus, a modification or modulation of HCNc in reaction to the environment can only be achieved from one to the next generation when under genetic control and within days or hours when transcriptional regulations are involved. In the present study, it is shown that in rubber tree (Hevea brasiliensis) HCNc is modulated by post-translational activity regulation of the key enzymes for cyanide release. Methods Linamarase (LIN) and hydroxynitrile lyase (HNL) activity was determined by colorimetric assays utilizing dissociation of the substrates p-nitrophenyl-β-d-glucopyranoside and acetone cyanohydrin, respectively. Key Results In rubber tree leaves, LIN and HNL show up to ten-fold increased activity in response to tissue damage. This enzyme activation occurs within seconds and results in accelerated HCN formation. It is restricted to the damaged leaf area and depends on the severity of tissue damage. Conclusions LIN and HNL activation (in contrast to genetic and transcriptional regulations) allows an immediate, local and damage type-dependent modulation of the cyanogenic response. Accordingly, this post-translational activation plays a decisive role in the defence of H. brasiliensis against herbivores as well as pathogens and may allow more flexible

  20. Hormonal treatment of the bark of rubber trees (Hevea brasiliensis) increases latex yield through latex dilution in relation with the differential expression of two aquaporin genes.

    PubMed

    Tungngoen, Kessarin; Viboonjun, Unchera; Kongsawadworakul, Panida; Katsuhara, Maki; Julien, Jean-Louis; Sakr, Soulaiman; Chrestin, Hervé; Narangajavana, Jarunya

    2011-02-15

    Natural rubber is synthesized in laticifers in the inner liber of the rubber tree (Hevea brasiliensis). Upon bark tapping, the latex is expelled due to liber turgor pressure. The mature laticifers are devoid of plasmodesmata; therefore a corresponding decrease in the total latex solid content is likely to occur due to water influx inside the laticifers. Auxins and ethylene used as efficient yield stimulants in mature untapped rubber trees, but, bark treatments with abscisic acid (ABA) and salicylic acid (SA) could also induce a transient increase latex yield. We recently reported that there are three aquaporin genes, HbPIP2;1, HbTIP1;1 and HbPIP1;1, that are regulated differentially after ethylene bark treatment. HbPIP2;1 was up-regulated in both the laticifers and the inner liber tissues, whereas HbTIP1;1 was up-regulated in the latex cells, but very markedly down-regulated in the inner liber tissues. Conversely, HbPIP1;1 was down-regulated in both tissues. In the present study, HbPIP2;1 and HbTIP1;1 showed a similar expression in response to auxin, ABA and SA, as seen in ethylene stimulation, while HbPIP1;1 was slightly regulated by auxin, but neither by ABA nor SA. The analysis of the HbPIP1;1 promoter region indicated the presence of only ethylene and auxin responsive elements. In addition, the poor efficiency of this HbPIP1;1 in increasing plasmalemma water conductance was confirmed in Xenopus oocytes. Thus, an increase in latex yield in response to all of these hormones was proposed to be the major function of aquaporins, HbPIP2;1 and HbTIP1;1. This study emphasized that the circulation of water between the laticifers and their surrounding tissues that result in latex dilution, as well as the probable maintenance of the liber tissues turgor pressure, favor the prolongation of latex flow.

  1. Initiator-independent and initiator-dependent rubber biosynthesis in Ficus elastica.

    PubMed

    Espy, Stephanie C; Keasling, Jay D; Castillón, Javier; Cornish, Katrina

    2006-04-15

    The rubber-producing tree, Ficus elastica (the Indian rubber tree), requires the same substrates for rubber production as other rubber-producing plants, such as Hevea brasiliensis (the Brazilian or Para rubber tree), the major source of commercial natural rubber in the world, and Parthenium argentatum (guayule), a widely studied alternative for natural rubber production currently under commercial development. Rubber biosynthesis can be studied, in vitro, using purified, enzymatically active rubber particles, an initiator such as FPP, IPP as the source of monomer, and a metal cofactor such as Mg2+. However, unlike H. brasiliensis and P. argentatum, we show that enzymatically active rubber particles purified from F. elastica are able to synthesize rubber, in vitro, in the absence of added initiator. In this paper, we characterize, for the first time, the kinetic differences between initiator-dependent rubber biosynthesis, and initiator-independent rubber biosynthesis, and the effect of cofactor concentration on both of these processes.

  2. Effect of non-rubber constituents on Guayule and Hevea rubber intrinsic properties

    USDA-ARS?s Scientific Manuscript database

    To meet the increasing demand for natural rubber (NR), currently sourced from the tropical rubber tree Hevea brasiliensis, and address price volatility and steadily increasing labor costs, alternate rubber-producing species are in commercial development. One of these, guayule (Parthenium argentatum)...

  3. Establishment of new crops for the production of natural rubber.

    PubMed

    van Beilen, Jan B; Poirier, Yves

    2007-11-01

    Natural rubber is a unique biopolymer of strategic importance that, in many of its most significant applications, cannot be replaced by synthetic alternatives. The rubber tree Hevea brasiliensis is the almost exclusive commercial source of natural rubber currently and alternative crops should be developed for several reasons, including: a disease risk to the rubber tree that could potentially decimate current production, a predicted shortage of natural rubber supply, increasing allergic reactions to rubber obtained from the Brazilian rubber tree and a general shift towards renewables. This review summarizes our knowledge of plants that can serve as alternative sources of natural rubber, of rubber biosynthesis and the scientific gaps that must be filled to bring the alternative crops into production.

  4. Somatic embryogenesis in forestry: A practical approach to cloning the best trees

    Treesearch

    Alex M. Diner

    1999-01-01

    Trees as well as humans have two basic cell types based on genetic content: somatic cells and gametic or reproductive cells. Somatic cells, such as skin cells or the sapwood cells in a tree, have at least twice (2n) the base set of chromosomes. The reproductive cells (gametic cells) have a single (n) set of chromosomes.

  5. Regulation of HbPIP2;3, a Latex-Abundant Water Transporter, Is Associated with Latex Dilution and Yield in the Rubber Tree (Hevea brasiliensis Muell. Arg.)

    PubMed Central

    Cai, Xiuqing; Wang, Jin; Rookes, James; Lin, Weifu; Cahill, David; Kong, Lingxue

    2015-01-01

    Rubber tree (Hevea brasiliensis) latex, the source of natural rubber, is synthesised in the cytoplasm of laticifers. Efficient water inflow into laticifers is crucial for latex flow and production since it is the determinant of the total solid content of latex and its fluidity after tapping. As the mature laticifer vessel rings are devoid of plasmodesmata, water exchange between laticifers and surrounding cells is believed to be governed by plasma membrane intrinsic proteins (PIPs). To identify the most important PIP aquaporin in the water balance of laticifers, the transcriptional profiles of ten-latex-expressed PIPs were analysed. One of the most abundant transcripts, designated HbPIP2;3, was characterised in this study. When tested in Xenopus laevis oocytes HbPIP2;3 showed a high efficiency in increasing plasmalemma water conductance. Expression analysis indicated that the HbPIP2;3 gene was preferentially expressed in latex, and the transcripts were up-regulated by both wounding and exogenously applied Ethrel (a commonly-used ethylene releaser). Although regular tapping up-regulated the expression of HbPIP2;3 during the first few tappings of the virginal rubber trees, the transcriptional kinetics of HbPIP2;3 to Ethrel stimulation in the regularly tapped tree exhibited a similar pattern to that of the previously reported HbPIP2;1 in the virginal rubber trees. Furthermore, the mRNA level of HbPIP2;3 was associated with clonal yield potential and the Ethrel stimulation response. Together, these results have revealed the central regulatory role of HbPIP2;3 in laticifer water balance and ethylene stimulation of latex production in Hevea. PMID:25927524

  6. Regulation of HbPIP2;3, a Latex-Abundant Water Transporter, Is Associated with Latex Dilution and Yield in the Rubber Tree (Hevea brasiliensis Muell. Arg.).

    PubMed

    An, Feng; Zou, Zhi; Cai, Xiuqing; Wang, Jin; Rookes, James; Lin, Weifu; Cahill, David; Kong, Lingxue

    2015-01-01

    Rubber tree (Hevea brasiliensis) latex, the source of natural rubber, is synthesised in the cytoplasm of laticifers. Efficient water inflow into laticifers is crucial for latex flow and production since it is the determinant of the total solid content of latex and its fluidity after tapping. As the mature laticifer vessel rings are devoid of plasmodesmata, water exchange between laticifers and surrounding cells is believed to be governed by plasma membrane intrinsic proteins (PIPs). To identify the most important PIP aquaporin in the water balance of laticifers, the transcriptional profiles of ten-latex-expressed PIPs were analysed. One of the most abundant transcripts, designated HbPIP2;3, was characterised in this study. When tested in Xenopus laevis oocytes HbPIP2;3 showed a high efficiency in increasing plasmalemma water conductance. Expression analysis indicated that the HbPIP2;3 gene was preferentially expressed in latex, and the transcripts were up-regulated by both wounding and exogenously applied Ethrel (a commonly-used ethylene releaser). Although regular tapping up-regulated the expression of HbPIP2;3 during the first few tappings of the virginal rubber trees, the transcriptional kinetics of HbPIP2;3 to Ethrel stimulation in the regularly tapped tree exhibited a similar pattern to that of the previously reported HbPIP2;1 in the virginal rubber trees. Furthermore, the mRNA level of HbPIP2;3 was associated with clonal yield potential and the Ethrel stimulation response. Together, these results have revealed the central regulatory role of HbPIP2;3 in laticifer water balance and ethylene stimulation of latex production in Hevea.

  7. Increased vascular permeability, angiogenesis and wound healing induced by the serum of natural latex of the rubber tree Hevea brasiliensis.

    PubMed

    Mendonça, Ricardo José; Maurício, Vanessa Beatriz; Teixeira, Larissa de Bortolli; Lachat, João José; Coutinho-Netto, Joaquim

    2010-05-01

    Increases in vascular permeability and angiogenesis are crucial events to wound repair, tumoral growth and revascularization of tissues submitted to ischemia. An increased vascular permeability allows a variety of cytokines and growth factors to reach the damaged tissue. Nevertheless, the angiogenesis supply tissues with a wide variety of nutrients and is also important to metabolites clearance. It has been suggested that the natural latex from Hevea brasiliensis showed wound healing properties and angiogenic activity. Thus, the purpose of this work was to characterize its angiogenic activity and its effects on vascular permeability and wound healing. The serum fraction of the latex was separated from the rubber with reduction of the pH. The activity of the dialyzed serum fraction on the vascular permeability injected in subcutaneous tissue was assayed according Mile's method. The angiogenic activity was determined using a chick embryo chorioallantoic membrane assay and its effects on the wound-healing process was determined by the rabbit ear dermal ulcer model. The serum fraction showed evident angiogenic effect and it was effective in enhancing vascular permeability. In dermal ulcers, this material significantly accelerated wound healing. Moreover, the serum fraction boiled and treated with proteases lost these activities. These results are in accordance with the enhancement of wound healing observed in clinical trials carried out with a biomembrane prepared with the same natural latex.

  8. The control by delta mu H+ of the tonoplast-bound H+-translocating adenosine triphosphatase from rubber-tree (Hevea brasiliensis) latex.

    PubMed Central

    Marin, B P

    1985-01-01

    The relationship between tonoplast-bound ATPase activity and the magnitude of the electrochemical proton gradient has been investigated on tightly sealed vesicles prepared from rubber-tree (Hevea brasiliensis) latex. A variety of methods have been used to modify, either alone or together, the two components of the electrochemical proton gradient (delta mu H+). When the delta pH component was decreased either by titration with (NH4)2SO4 or by addition of protonophores or nigericin in the presence of K+, ATPase activity was stimulated. On the other hand, when the delta psi component was decreased either by addition of lipophilic cations or by addition of valinomycin in the presence of K+, ATPase activity decreased. It is concluded that activity of the tonoplast-bound ATPase is regulated by changes in the electrochemical proton gradient across the tonoplast, so that, once the maximum proton gradient is established across the tonoplast, any perturbation of the equilibrium state should result in the increased rate of ATP hydrolysis as the enzyme attempts to re-establish the initial gradient. PMID:2994636

  9. Evaluation of the Antibacterial and Antifungal Properties of Phragmanthera capitata (Sprengel) Balle (Loranthaceae), a Mistletoe Growing on Rubber Tree, Using the Dilution Techniques

    PubMed Central

    2017-01-01

    The alarming increase in multidrug resistance of pathogenic microorganisms to conventional drugs in recent years has prompted the search for new leads in alternative remedies in natural products. Hence, this study was aimed at evaluating the antimicrobial properties of Phragmanthera capitata, a parasitic mistletoe growing on rubber trees. The in vitro antimicrobial activities of the acetone, methanol, ethanol, and aqueous extracts were investigated using five gram-negative and five gram-positive bacteria and four fungi. A 96-well resazurin broth and agar dilution techniques were used for the determination of the Minimum Inhibitory and Bactericidal Concentrations. The antibacterial activity of the organic extracts had comparative effects on all the bacteria with a MIC of 1.25 to 5 mg/mL and MBC of 2.5 to 10 mg/mL. However, the acetone extract showed higher bactericidal effect while the aqueous extract was not active. The organic solvent extracts also showed antifungal activities on two of the fungi with a MIC of 1.25 mg/mL to 10 mg/mL. However, the aqueous extract had the highest activity inhibiting all the fungi with a MIC of ≤0.3125 to 1.25 mg/mL. The study supports the ethnomedicinal claims of P. capitata as a remedy for the diseases/infections caused by these organisms. PMID:28642934

  10. De novo Transcriptome Analysis Reveals Distinct Defense Mechanisms by Young and Mature Leaves of Hevea brasiliensis (Para Rubber Tree)

    PubMed Central

    Fang, Yongjun; Mei, Hailiang; Zhou, Binhui; Xiao, Xiaohu; Yang, Meng; Huang, Yacheng; Long, Xiangyu; Hu, Songnian; Tang, Chaorong

    2016-01-01

    Along with changes in morphology in the course of maturation, leaves of Hevea brasiliensis become more resistant to leaf diseases, including the South American Leaf Blight (SALB), a devastating fungal disease of this economically important tree species. To understand the underlying mechanisms of this defense, and to identify the candidate genes involved, we sequenced the Hevea leaf transcriptome at four developmental stages (I to IV) by Illumina sequencing. A total of 62.6 million high-quality reads were generated, and assembled into 98,796 unique transcripts. We identified 3,905 differentially expressed genes implicated in leaf development, 67.8% (2,651) of which were during the transition to leaf maturation. The genes involved in cyanogenic metabolism, lignin and anthocyanin biosynthesis were noteworthy for their distinct patterns of expression between developing leaves (stages I to III) and mature leaves (stage IV), and the correlation with the change in resistance to SALB and the Oidium/Colletotrichum leaf fall. The results provide a first profile of the molecular events that relate to the dynamics of leaf morphology and defense strategies during Hevea leaf development. This dataset is beneficial to devising strategies to engineer resistance to leaf diseases as well as other in-depth studies in Hevea tree. PMID:27619402

  11. Rubber Reclamation

    ERIC Educational Resources Information Center

    Williams, Kathryn R.

    2007-01-01

    The safety and health hazards related to recycling of used rubber, due to the scarcity and high price of virgin rubber are reported. Various threats like stagnant water pools trapped in tires leading to diseases and ignited tires, which become very difficult to extinguish and generating smoke that is extremely detrimental to the environment, have…

  12. Rubber Reclamation

    ERIC Educational Resources Information Center

    Williams, Kathryn R.

    2007-01-01

    The safety and health hazards related to recycling of used rubber, due to the scarcity and high price of virgin rubber are reported. Various threats like stagnant water pools trapped in tires leading to diseases and ignited tires, which become very difficult to extinguish and generating smoke that is extremely detrimental to the environment, have…

  13. Cloning and characterization of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway genes of a natural-rubber producing plant, Hevea brasiliensis.

    PubMed

    Sando, Tomoki; Takeno, Shinya; Watanabe, Norie; Okumoto, Hiroshi; Kuzuyama, Tomohisa; Yamashita, Atsushi; Hattori, Masahira; Ogasawara, Naotake; Fukusaki, Eiichiro; Kobayashi, Akio

    2008-11-01

    Natural rubber is synthesized as rubber particles in the latex, the fluid cytoplasm of laticifers, of Hevea brasiliensis. Although it has been found that natural rubber is biosynthesized through the mevalonate pathway, the involvement of an alternative 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway is uncertain. We obtained all series of the MEP pathway candidate genes by analyzing expressed sequence tag (EST) information and degenerate PCR in H. brasiliensis. Complementation experiments with Escherichia coli mutants were performed to confirm the functions of the MEP pathway gene products of H. brasiliensis together with those of Arabidopsis thaliana, and it was found that 1-deoxy-D-xylulose-5-phosphate reductoisomerase, 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase, and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase of H. brasiliensis were functionally active in the E. coli mutants. Gene expression analysis revealed that the expression level of the HbDXS2 gene in latex was relatively high as compared to those of other MEP pathway genes. However, a feeding experiment with [1-(13)C] 1-deoxy-D-xylulose triacetate, an intermediate derivative of the MEP pathway, indicated that the MEP pathway is not involved in rubber biosynthesis, but is involved in carotenoids biosynthesis in H. brasiliensis.

  14. Microstructure of Purified Rubber Particles.

    PubMed

    Wood; Cornish

    2000-05-01

    Purified rubber particles from Hevea brasiliensis (Brazilian rubber tree), Parthenium argentatum (guayule), Ficus elastica (Indian rubber tree), and Euphorbia lactiflua were examined and compared using conventional scanning electron microscopy (SEM), field-emission SEM, cryo-SEM, and transmission electron microscopy (TEM). Rubber particles of all four species were spherical; they varied in size and had a uniform homogeneous material, the rubber core, surrounded by a contiguous monolayer (half-unit) membrane. Frozen-hydrated and/or untreated particles from H. brasiliensis and P. argentatum deformed and fused readily, whereas those from F. elastica and E. lactiflua retained their spherical shapes. These results indicate that the surface components of the H. brasiliensis and P. argentatum particles are more fluid than those of F. elastica or E. lactiflua. When fixed in aldehyde, F. elastica particles retained their spherical exterior shapes but had hollow centers, whereas H. brasiliensis and P. argentatum particles completely collapsed. In aldehyde-osmium tetroxide-fixed material, the rubber core of F. elastica was poorly preserved in some particles in which only a small amount of the rubber core remained adhering to the monolayer membrane, leaving a hollow center. Euphorbia lactiflua particles were well preserved in terms of retaining the rubber core; however, the membrane was not as easily discernible as it was in the other three species. Both H. brasiliensis and P. argentatum were well preserved following fixation; their cores remained filled with rubber, and their monolayer membranes were defined. The addition of potassium permanganate to the fixation-staining regime resulted in higher-contrast micrographs and more well defined monolayer membranes.

  15. Unraveling the Mystery of Natural Rubber Biosynthesis

    USDA-ARS?s Scientific Manuscript database

    Natural rubber (NR) is primarily obtained from Hevea brasiliensis, commonly known as the Brazilian rubber tree. As this species contains little genetic variation, it is susceptible to pathogen-based eradication. Consequently, it is imperative that a biomimetic pathway for NR production be developed....

  16. Identification of an Endophytic Antifungal Bacterial Strain Isolated from the Rubber Tree and Its Application in the Biological Control of Banana Fusarium Wilt.

    PubMed

    Tan, Deguan; Fu, Lili; Han, Bingyin; Sun, Xuepiao; Zheng, Peng; Zhang, Jiaming

    2015-01-01

    Banana Fusarium wilt (also known as Panama disease) is one of the most disastrous plant diseases. Effective control methods are still under exploring. The endophytic bacterial strain ITBB B5-1 was isolated from the rubber tree, and identified as Serratia marcescens by morphological, biochemical, and phylogenetic analyses. This strain exhibited a high potential for biological control against the banana Fusarium disease. Visual agar plate assay showed that ITBB B5-1 restricted the mycelial growth of the pathogenic fungus Fusarium oxysporum f. sp. cubense race 4 (FOC4). Microscopic observation revealed that the cell wall of the FOC4 mycelium close to the co-cultured bacterium was partially decomposed, and the conidial formation was prohibited. The inhibition ratio of the culture fluid of ITBB B5-1 against the pathogenic fungus was 95.4% as estimated by tip culture assay. Chitinase and glucanase activity was detected in the culture fluid, and the highest activity was obtained at Day 2 and Day 3 of incubation for chitinase and glucanase, respectively. The filtrated cell-free culture fluid degraded the cell wall of FOC4 mycelium. These results indicated that chitinase and glucanase were involved in the antifungal mechanism of ITBB B5-1. The potted banana plants that were inoculated with ITBB B5-1 before infection with FOC4 showed 78.7% reduction in the disease severity index in the green house experiments. In the field trials, ITBB B5-1 showed a control effect of approximately 70.0% against the disease. Therefore, the endophytic bacterial strain ITBB B5-1 could be applied in the biological control of banana Fusarium wilt.

  17. Identification of an Endophytic Antifungal Bacterial Strain Isolated from the Rubber Tree and Its Application in the Biological Control of Banana Fusarium Wilt

    PubMed Central

    Sun, Xuepiao; Zheng, Peng; Zhang, Jiaming

    2015-01-01

    Banana Fusarium wilt (also known as Panama disease) is one of the most disastrous plant diseases. Effective control methods are still under exploring. The endophytic bacterial strain ITBB B5-1 was isolated from the rubber tree, and identified as Serratia marcescens by morphological, biochemical, and phylogenetic analyses. This strain exhibited a high potential for biological control against the banana Fusarium disease. Visual agar plate assay showed that ITBB B5-1 restricted the mycelial growth of the pathogenic fungus Fusarium oxysporum f. sp. cubense race 4 (FOC4). Microscopic observation revealed that the cell wall of the FOC4 mycelium close to the co-cultured bacterium was partially decomposed, and the conidial formation was prohibited. The inhibition ratio of the culture fluid of ITBB B5-1 against the pathogenic fungus was 95.4% as estimated by tip culture assay. Chitinase and glucanase activity was detected in the culture fluid, and the highest activity was obtained at Day 2 and Day 3 of incubation for chitinase and glucanase, respectively. The filtrated cell-free culture fluid degraded the cell wall of FOC4 mycelium. These results indicated that chitinase and glucanase were involved in the antifungal mechanism of ITBB B5-1. The potted banana plants that were inoculated with ITBB B5-1 before infection with FOC4 showed 78.7% reduction in the disease severity index in the green house experiments. In the field trials, ITBB B5-1 showed a control effect of approximately 70.0% against the disease. Therefore, the endophytic bacterial strain ITBB B5-1 could be applied in the biological control of banana Fusarium wilt. PMID:26133557

  18. [Comparison of the water consumption characteristics of Eucalyptus and Corymbia clone seedlings and the local indigenous tree species Bischofia javanica].

    PubMed

    Hua, Lei; He, Qian; Li, Ji-Yue; Liu, Shan; Yu, Fei

    2014-06-01

    The water consumption, water consumption rate, net photosynthetic rate (Pn), transpiration rate (Tr) and water use efficiency (WUE) of Eucalyptus urophylla x E. grandis DH33-27, E. urophylla x E. grandis DH32-29, E. grandis H1, Corymbia ptychocarpa and an indigenous tree species Bischofia javanica were studied in normal soil moisture condition. The average daily water consumption of the five tree species was in the order of E. urophylla x E. grandis DH32-29 (188.47 +/- 14. 91) g > E. urophylla x E. grandis DH33-27 (169.27 +/- 16.26) g > E. grandis H1 (118.65 +/- 5.32) g > B. javanica (38.12 +/- 1.46) g > C. ptychocarpa (20.13 +/- 1.72) g, which had obviously positive correlation with the total leaf area of each seedling. The water consumption was mostly in the daytime, which took 90% of the whole day water consumption. The daily change of the water consumption rates of 5 kinds of seedlings followed the curve with one peak at 12:00-14:00. The total water consumption ability of Eucalyptus and Corymbia was higher than that of B. javanica. The water consumption rate of C. ptychocarpa was far higher than that of the other 4 kinds of seedlings, so its large area planting should be given full consideration to this issue. The change in water consumption rate of E. urophylla x E. grandis DH33-27 was mostly impacted by environmental temperature and humidity, because its water consumption rate was the smallest among 4 kinds of Eucalyptus and Corymbia seedlings during the daytime with high temperature and low humidity. The four clone seedlings of Eucalyptus and Corymbia showed higher photosynthetic rates and transpiration rates compared with B. javanica. Two clone seedlings of E. urophylla x E. grandis had better water-saving performance. The WUE of Eucalyptus and Corymbia was higher than that of B. javanica in general, except E. urophylla x E. Grandis DH33-27.

  19. Trees

    ERIC Educational Resources Information Center

    Al-Khaja, Nawal

    2007-01-01

    This is a thematic lesson plan for young learners about palm trees and the importance of taking care of them. The two part lesson teaches listening, reading and speaking skills. The lesson includes parts of a tree; the modal auxiliary, can; dialogues and a role play activity.

  20. Efficacy of a mermithid nematode Romanomermis iyengari (Welch) (Nematoda: Mermithidae) in controlling tree hole-breeding mosquito Aedes albopictus (Skuse) (Diptera: Culicidae) in a rubber plantation area of Kerala, India.

    PubMed

    Paily, K P; Chandhiran, K; Vanamail, P; Kumar, N Pradeep; Jambulingam, P

    2013-03-01

    In rubber plantations, tree holes are one of the major types of breeding habitats of Aedes mosquitoes which transmit dengue and chikungunya. A mermithid nematode, Romanomermis iyengari, was evaluated in tree holes for its efficacy in controlling Aedes albopictus. Infection of mosquito larvae by the nematode was determined through microscopic examination on the next day of application, and evaluation of immature density of mosquito was done on the seventh day. After application of the infective stage of the nematode in a host-parasite ratio of 1:3 or 1:4, the infection rates on the different larval instars of mosquito were similar, 85.7-95.8 % in first to third instars and 79.3 % in fourth instar larvae or 100 and 92.9 %, respectively. Parasite burden varied from 1.1 to 2.4, respectively, among first and third instar larvae applied at 1:3. At 1:4, the parasite burden was between 1.6 (fourth instar) and 4 (second instar). The increase in parasite burden due to parasite density was significant in all the larval instars (P < 0.05). High parasite burden is detrimental to parasite recycling as it can cause premature mortality of the host. Hence, the dosage of 1:3 could be considered as suitable for rubber tree hole habitats. In the nematode-applied tree holes, there was a significant level (P < 0.05) of reduction in the immature density of A. albopictus, especially late instars and pupae, confirming the efficacy of R. iyengari in infecting the mosquito and controlling pupal emergence.

  1. Estimation of Biomass and Carbon Stocks in Rubber Plantation Using Thaichote Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Charoenjit, Kitsanai; Zuddas, Pierpaolo; Allemand, Pascal

    2014-05-01

    This goal of study is to improve model for estimate biomass and carbon stocks of rubber plantation (clone RRIM 600) in sub-basin of mae num prasae, East Thailand with total area is 232 Km2. We mapped 2011 of the biomass and carbon stocks with the used of integrated Thaichote satellite imagery and field data. In order to tree girth prediction and tree density population, we applied the objected based image analysis (OBIA) which include image mining and modeling by linear multiple regression, then estimate biomass and carbon stocks in rubber plantation. The image mining includes spectral, vegetation, textural and mask information for modeling construction. We found an parameters of the Global Environmental Monitoring Index (GEMI) and texture of homogeneity, dissimilarity, contrast and variance were accepted relationship of tree girt prediction with R2 0.865. The total amount of biomass and carbon stocks in study area is 2,227 Kt and 991.5 KtC respectively. For summary of study area, the annual sequestered in 2011 is 121.3 tCO2 from the atmosphere and the rubber plantation at mature age stage (25 years) had highest capacity of sequestered at 33.53 tCO2 ha-1 yr-1.

  2. Guayule and Russian dandelion as alternative sources of natural rubber.

    PubMed

    van Beilen, Jan B; Poirier, Yves

    2007-01-01

    Natural rubber, obtained almost exclusively from the Para rubber tree (Hevea brasiliensis), is a unique biopolymer of strategic importance that, in many of its most significant applications, cannot be replaced by synthetic rubber alternatives. Several pressing motives lead to the search for alternative sources of natural rubber. These include increased evidence of allergenic reactions to Hevea rubber, the danger that the fungal pathogen Microcyclus ulei, causative agent of South American Leaf Blight (SALB), might spread to Southeast Asia, which would severely disrupt rubber production, potential shortages of supply due to increasing demand and changes in land use, and a general trend towards the replacement of petroleum-derived chemicals with renewables. Two plant species have received considerable attention as potential alternative sources of natural rubber: the Mexican shrub Guayule (Parthenium argentatum Gray) and the Russian dandelion (Taraxacum koksaghyz). This review will summarize the current production methods and applications of natural rubber (dry rubber and latex), the threats to the production of natural rubber from the rubber tree, and describe the current knowledge of the production of natural rubber from guayule and Russian dandelion.

  3. Cloning and expression of Ole e I, the major allergen from olive tree pollen. Polymorphism analysis and tissue specificity.

    PubMed

    Villalba, M; Batanero, E; Monsalve, R I; González de la Peña, M A; Lahoz, C; Rodríguez, R

    1994-05-27

    Ole e I, the major allergen from the olive tree (Olea europaea), is one of the main causes of allergy in Mediterranean countries and some areas of North America. The cloning and sequencing of several cDNAs coding for the olive allergen have been achieved. cDNA has been synthesized from total pollen RNA and amplified by using the polymerase chain reaction. The nucleotide sequence data demonstrate the existence of microheterogeneities in at least 37 positions out of the 145 amino acids of Ole e I, thus explaining the high degree of polymorphism exhibited by the natural protein. One of the sequenced cDNAs encoding a full-length isoform was inserted into the plasmid vector pGEX-2T and overexpressed. The recombinant Ole e I has been produced in Escherichia coli as a fusion protein with glutathione S-transferase of Schistosoma japonicum. This chimeric protein was purified by affinity chromatography on a glutathione-Sepharose 4B column and digested with thrombin to release the recombinant allergen. Both the fusion protein and the recombinant Ole e I were recognized in Western blot analysis by rabbit polyclonal and mouse monoclonal antisera raised against native Ole e I as well as by the IgE of olive pollen-sensitive human sera. This indicates that the recombinant production of individual isoforms may be useful for the improvement of reagents to be used in diagnosis and therapy of IgE-mediated disorders. In addition, Ole e I mRNA has been observed to be pollen-specific as shown in a Northern blot analysis.

  4. Structural characterization of rubber from jackfruit and euphorbia as a model of natural rubber.

    PubMed

    Mekkriengkrai, Dararat; Ute, Koiichi; Swiezewska, Ewa; Chojnacki, Tadeusz; Tanaka, Yasuyuki; Sakdapipanich, Jitladda T

    2004-01-01

    A structural study of low molecular weight rubbers from Jackfruit (Artocarpus heterophyllus) and Painted spurge (Euphorbia heterophylla) was carried out as model compounds of natural rubber from Hevea brasiliensis. The rubber content of latex from Jackfruit was 0.4-0.7%, which is very low compared with that of 30-35% in the latex from Hevea tree. The rubber from Jackfruit latex was low molecular weight with narrow unimodal molecular weight distribution (MWD), whereas that obtained from E. heterophylla showed very broad MWD. The 1H and 13C NMR analyses showed that Jackfruit rubber consists of a dimethylallyl group and two trans-isoprene units connected to a long sequence of cis-isoprene units. The alpha-terminal group of Jackfruit rubber was presumed to be composed of a phosphate group based on the presence of 1H NMR signal at 4.08 ppm corresponding to the terminal =CH-CH2OP group.

  5. Molecular cloning and expression profile of ß-ketoacyl-acp synthase gene from tung tree (Vernicia fordii Hemsl.)

    USDA-ARS?s Scientific Manuscript database

    Tung tree (Vernicia fordii) is an important woody oil tree. Tung tree seeds contain 50-60% oil with approximately 80 mole a-eleostearic acid (9cis, 11trans, 13trans octadecatrienoic acid). Fatty acid synthesis is catalyzed by the concerted action of acetyl-CoA carboxylase and fatty acid synthase, a ...

  6. Alternative sources of natural rubber.

    PubMed

    Mooibroek, H; Cornish, K

    2000-04-01

    Rubber (cis-1,4-polyisoprene) is one of the most important polymers naturally produced by plants because it is a strategic raw material used in more than 40,000 products, including more than 400 medical devices. The sole commercial source, at present, is natural rubber harvested from the Brazilian rubber tree, Hevea brasiliensis. Primarily due to its molecular structure and high molecular weight (> 1 million daltons) this rubber has high performance properties that cannot easily be mimicked by artificially produced polymers, such as those derived from, e.g., bacterial poly-hydroxyalkanoates (PHAs). These high performance properties include resilience, elasticity, abrasion resistance, efficient heat dispersion (minimizing heat build-up under friction), and impact resistance. Medical rubber gloves need to fit well, be break-resistant, allow the wearer to retain fine tactile sensation, and provide an effective barrier against pathogens. The sum of all these characteristics cannot yet be achieved using synthetic gloves. The lack of biodiversity in natural rubber production renders continuity of supply insecure, because of the risk of crop failure, diminishing acreage, and other disadvantages outlined below. A search for alternative sources of natural rubber production has already resulted in a large number of interesting plants and prospects for immediate industrial exploitation of guayule (Parthenium argentatum) as a source of high quality latex. Metabolic engineering will permit the production of new crops designed to accumulate new types of valued isoprenoid metabolites, such as rubber and carotenoids, and new combinations extractable from the same crop. Currently, experiments are underway to genetically improve guayule rubber production strains in both quantitative and qualitative respects. Since the choice for gene activities to be introduced or changed is under debate, we have set up a complementary approach to guayule with yeast species, which may more quickly

  7. Trees

    NASA Astrophysics Data System (ADS)

    Epstein, Henri

    2016-11-01

    An algebraic formalism, developed with V. Glaser and R. Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large category of space-times.

  8. Natural rubber (NR) biosynthesis: perspectives from polymer chemistry

    SciTech Connect

    Barkakaty, Balaka

    2014-01-01

    Natural rubber is an important strategic raw material for manufacturing a wide variety of industrial products. There are at least 2,500 different latex-producing plant species; however, only Hevea brasiliensis (the Brazilian rubber tree) is a commercial source. The chemical structure of natural rubber is cis-1,4-polyisoprene, but the exact structure of the head and end groups remains unknown. Since synthetic cis-1,4-polyisoprenes cannot match the superior properties of natural rubber, understanding the chemistry behind the biosynthetic process is key to finding a possible replacement. T his chapter summarizes our current understandings from the perspective of a polymer scientist by comparing synthetic polyisoprenes to natural rubber. The chapter also highlights biomimetic polymerization, research towards a synthetic match of natural rubber and the role of natural rubber in health care.

  9. Ethrel-stimulated prolongation of latex flow in the rubber tree (Hevea brasiliensis Muell. Arg.): an Hev b 7-like protein acts as a universal antagonist of rubber particle aggregating factors from lutoids and C-serum.

    PubMed

    Shi, Min-Jing; Cai, Fu-Ge; Tian, Wei-Min

    2016-02-01

    Ethrel is the most effective stimuli in prolonging the latex flow that consequently increases yield per tapping. This effect is largely ascribed to the enhanced lutoid stability, which is associated with the decreased release of initiators of rubber particle (RP) aggregation from lutoid bursting. However, the increase in both the bursting index of lutoids and the duration of latex flow after applying ethrel or ethylene gas in high concentrations suggests that a new mechanism needs to be introduced. In this study, a latex allergen Hev b 7-like protein in C-serum was identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS). In vitro analysis showed that the protein acted as a universal antagonist of RP aggregating factors from lutoids and C-serum. Ethrel treatment obviously weakened the effect of C-serum on RP aggregation, which was closely associated with the increase in the level of the Hev b 7-like protein and the decrease in the level of the 37 kDa protein, as revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), western blotting analysis and antibody neutralization. Thus, the increase of the Hev b 7-like protein level or the ratio of the Hev b 7-like protein to the 37 kDa protein in C-serum should be primarily ascribed to the ethrel-stimulated prolongation of latex flow duration.

  10. Ethrel-stimulated prolongation of latex flow in the rubber tree (Hevea brasiliensis Muell. Arg.): an Hev b 7-like protein acts as a universal antagonist of rubber particle aggregating factors from lutoids and C-serum

    PubMed Central

    Shi, Min-Jing; Cai, Fu-Ge; Tian, Wei-Min

    2016-01-01

    Ethrel is the most effective stimuli in prolonging the latex flow that consequently increases yield per tapping. This effect is largely ascribed to the enhanced lutoid stability, which is associated with the decreased release of initiators of rubber particle (RP) aggregation from lutoid bursting. However, the increase in both the bursting index of lutoids and the duration of latex flow after applying ethrel or ethylene gas in high concentrations suggests that a new mechanism needs to be introduced. In this study, a latex allergen Hev b 7-like protein in C-serum was identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS). In vitro analysis showed that the protein acted as a universal antagonist of RP aggregating factors from lutoids and C-serum. Ethrel treatment obviously weakened the effect of C-serum on RP aggregation, which was closely associated with the increase in the level of the Hev b 7-like protein and the decrease in the level of the 37 kDa protein, as revealed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), western blotting analysis and antibody neutralization. Thus, the increase of the Hev b 7-like protein level or the ratio of the Hev b 7-like protein to the 37 kDa protein in C-serum should be primarily ascribed to the ethrel-stimulated prolongation of latex flow duration. PMID:26381537

  11. Identification and subcellular localization analysis of two rubber elongation factor isoforms on Hevea brasiliensis rubber particles.

    PubMed

    Dai, Longjun; Nie, Zhiyi; Kang, Guijuan; Li, Yu; Zeng, Rizhong

    2017-02-01

    Rubber elongation factor (REF) is the most abundant protein found on the rubber particles or latex from Hevea brasiliensis (the Para rubber tree) and is considered to play important roles in natural rubber (cis-polyisoprene) biosynthesis. 16 BAC (benzyldimethyl-n-hexadecylammonium chloride)/SDS-PAGE separations and mass spectrometric identification had revealed that two REF isoforms shared similar amino acid sequences and common C-terminal sequences. In this study, the gene sequences encoding these two REF isoforms (one is 23.6 kDa in size with 222 amino acid residues and the other is 27.3 kDa in size with 258 amino acid residues) were obtained. Their proteins were relatively enriched by sequential extraction of the rubber particle proteins and separated by 16 BAC/SDS-PAGE. The localization of these isoforms on the surfaces of rubber particles was further verified by western blotting and immunogold electron microscopy, which demonstrated that these two REF isoforms are mainly located on the surfaces of larger rubber particles and that they bind more tightly to rubber particles than the most abundant REF and SRPP (small rubber particle protein).

  12. Cloning and characterization of HbMT2a, a metallothionein gene from Hevea brasiliensis Muell. Arg differently responds to abiotic stress and heavy metals

    SciTech Connect

    Li, Yan; Chen, Yue Yi; Yang, Shu Guang; Tian, Wei Min

    2015-05-22

    Metallothioneins (MTs) are of low molecular mass, cysteine-rich proteins. They play an important role in the detoxification of heavy metals and homeostasis of intracellular metal ions, and protecting against intracellular oxidative damages. In this study a full-length cDNA of type 2 plant metallothioneins, HbMT2a, was isolated from 25 mM Polyethyleneglycol (PEG) stressed leaves of Hevea brasiliensis by RACE. The HbMT2a was 372 bp in length and had a 237 bp open reading frame (ORF) encoding for a protein of 78 amino acid residues with molecular mass of 7.772 kDa. The expression of HbMT2a in the detached leaves of rubber tree clone RY7-33-97 was up-regulated by Me-JA, ABA, PEG, H{sub 2}O{sub 2}, Cu{sup 2+} and Zn{sup 2+}, but down-regulated by water. The role of HbMT2a protein in protecting against metal toxicity was demonstrated in vitro. PET-28a-HbMT2-beared Escherichia coli. Differential expression of HbMT2a upon treatment with 10 °C was observed in the detached leaves of rubber tree clone 93-114 which is cold-resistant and Reken501 which is cold-sensitive. The expression patterns of HbMT2a in the two rubber tree clones may be ascribed to a change in the level of endogenous H{sub 2}O{sub 2}. - Highlights: • Cloning an HbMT2a gene from rubber tree. • Analyzing expression patterns of HbMT2a upon abiotic stress and heavy metal stress. • Finding different expression patterns of HbMT2a among two Hevea germplasm. • The expressed protein of HbMT2a enhances copper and zinc tolerance in Escherichia coli.

  13. Cloning and characterisation of JAZ gene family in Hevea brasiliensis.

    PubMed

    Hong, H; Xiao, H; Yuan, H; Zhai, J; Huang, X

    2015-05-01

    Mechanical wounding or treatment with exogenous jasmonates (JA) induces differentiation of the laticifer in Hevea brasiliensis. JA is a key signal for latex biosynthesis and wounding response in the rubber tree. Identification of JAZ (jasmonate ZIM-domain) family of proteins that repress JA responses has facilitated rapid progress in understanding how this lipid-derived hormone controls gene expression and related physiological processes in plants. In this work, the full-length cDNAs of six JAZ genes were cloned from H. brasiliensis (termed HbJAZ). These HbJAZ have different lengths and sequence diversity, but all of them contain Jas and ZIM domains, and two of them contain an ERF-associated amphiphilic repression (EAR) motif in the N-terminal. Real-time RT-PCR analyses revealed that HbJAZ have different expression patterns and tissue specificity. Four HbJAZ were up-regulated, one was down-regulated, while two were less effected by rubber tapping treatment, suggesting that they might play distinct roles in the wounding response. A yeast two-hybrid assay revealed that HbJAZ proteins interact with each other to form homologous or heterogeneous dimer complexes, indicating that the HbJAZ proteins may expand their function through diverse JAZ-JAZ interactions. This work lays a foundation for identification of the JA signalling pathway and molecular mechanisms of latex biosynthesis in rubber trees.

  14. Silencing the lettuce homologs of small rubber particle protein does not influence natural rubber biosynthesis in lettuce (Lactuca sativa).

    PubMed

    Chakrabarty, Romit; Qu, Yang; Ro, Dae-Kyun

    2015-05-01

    Natural rubber, cis-1,4-polyisoprene, is an important raw material in chemical industries, but its biosynthetic mechanism remains elusive. Natural rubber is known to be synthesized in rubber particles suspended in laticifer cells in the Brazilian rubber tree (Hevea brasiliensis). In the rubber tree, rubber elongation factor (REF) and its homolog, small rubber particle protein (SRPP), were found to be the most abundant proteins in rubber particles, and they have been implicated in natural rubber biosynthesis. As lettuce (Lactuca sativa) can synthesize natural rubber, we utilized this annual, transformable plant to examine in planta roles of the lettuce REF/SRPP homologs by RNA interference. Among eight lettuce REF/SRPP homologs identified, transcripts of two genes (LsSRPP4 and LsSRPP8) accounted for more than 90% of total transcripts of REF/SRPP homologs in lettuce latex. LsSRPP4 displays a typical primary protein sequence as other REF/SRPP, while LsSRPP8 is twice as long as LsSRPP4. These two major LsSRPP transcripts were individually and simultaneously silenced by RNA interference, and relative abundance, polymer molecular weight, and polydispersity of natural rubber were analyzed from the LsSRPP4- and LsSRPP8-silenced transgenic lettuce. Despite previous data suggesting the implications of REF/SRPP in natural rubber biosynthesis, qualitative and quantitative alterations of natural rubber could not be observed in transgenic lettuce lines. It is concluded that lettuce REF/SRPP homologs are not critically important proteins in natural rubber biosynthesis in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. A study of amino acid modifiers in guayule natural rubber

    USDA-ARS?s Scientific Manuscript database

    Natural rubber from the Hevea tree is a critical agricultural material vital to United States industry, medicine, and defense, yet the country is dependent on imports to meet domestic needs. Guayule, a desert shrub indigenous to the US, is under development as an alternative source of natural rubber...

  16. History of Rubber and Its Use

    NASA Astrophysics Data System (ADS)

    Müller, Ingo; Strehlow, Peter

    Despite its spectacular properties rubber was not much good for anything before the latter part of the 19th century. To be sure the Aztecs had used it to make balls for their ceremonial ball games - or so we are told. But those games died along with the Aztec culture in the 16th century and there is no record of other useful applications until the late 18th century. But then, after that, rubber took off in a small way. After the American inventor Samuel Peal had obtained a patent in 1791 for the production of rubber-coated watertight textiles, the Scottish chemist Charles Macintosh (1766-1843) used such textiles for making rain-coats, and Thomas Hancock (1786-1865) produced rubber boots. At that time it was not really appropriate to speak of a rubber industry. What little material the evil-smelling workshops in New York and London needed, could be satisfied with the import of 30 tons of Caoutchouc1 annually - extracted from the sap of the tree Hevea brasiliensis - and most of that went for making erasers. Indeed, it had been reported by the English minister and scientist Joseph Priestley (1733-1804) that pieces of rubber are well-suited to rub out (sic!) pencil marks. Even today there is nothing better for the purpose and rubber became the English word for Caoutchouc.

  17. Organic acids and protein compounds causing the photoluminescence properties of natural rubber membranes and the quenching phenomena from Au nanoparticle incorporation.

    PubMed

    Cabrera, Flávio C; Agostini, Deuber L S; Dos Santos, Renivaldo J; Guimarães, Francisco E G; Guerrero, Ariel R; Aroca, Ricardo F; Job, Aldo E

    2014-12-01

    Natural rubber membranes were fabricated using latex from Hevea brasiliensis trees (clone RRIM 600) by casting, and controlling the time and temperature of thermal treatment. Three temperatures were used: 65, 80 and 120 °C and the corresponding annealing times of 6, 8, 10 and 12 h. The centrifugation of the latex produces the constituent phases: solid rubber (F1), serum or protein components (F2) and bottom fraction (F3). The photoluminescence properties could be correlated with organic acid components of latex. Natural rubber membranes were used as the active substrate (reducing agent) for the incorporation of colloidal Au nanoparticles synthesized by in situ reduction at different times. The intensity of photoluminescence bands assigned to the natural rubber decreases with the increase in amount of nanoparticles present on the membrane surface. It can be assumed that Au nanoparticles may be formed by reduction of the Au cation reacting with functional groups that are directly related to photoluminescence properties. However, the quenching of fluorescence may be attributed to the formation of a large amount of metal nanostructures on the natural rubber surface.

  18. Molecular cloning of an anuran V(2) type [Arg(8)] vasotocin receptor and mesotocin receptor: functional characterization and tissue expression in the Japanese tree frog (Hyla japonica).

    PubMed

    Kohno, Satomi; Kamishima, Yoshihisa; Iguchi, Taisen

    2003-07-01

    In most amphibians, [Arg(8)] vasotocin (VT) has an antidiuretic effect that is coupled to the activation of adenylate cyclase. In contrast, mesotocin (MT) has a diuretic effect and acts via the inositol phosphate/calcium signaling pathway in amphibians. To further clarify the mechanisms of VT and MT activation, we report the molecular cloning of a VT receptor (VTR) and a MT receptor (MTR) from the Japanese tree frog, Hyla japonica. Tree frog VTR or MTR cDNA encoded 363 or 389 amino acids, and their amino acid sequences revealed close similarity to the mammalian vasopressin V(2) (51-52% identity) or toad MT (94% identity) receptors, respectively. Using CHO-K1 cells transfected with tree frog VTR, we observed elevated concentrations of intracellular cAMP following exposure of the cells to VT or other neurohypophysial hormones, whereas the cells transfected with MTR did not exhibit altered cAMP concentrations. The cells transfected with VTR exhibited the following efficiency for cAMP accumulation: VT = hydrin 1 > or = vasopressin > or = hydrin 2 > MT = oxytocin > isotocin. VTR or MTR mRNA exhibits a single 2.2- or 5.5-kb transcription band, respectively, and both are expressed in various tissues. VTR mRNA is clearly expressed in brain, heart, kidney, pelvic patch of skin, and urinary bladder, whereas brain, fat body, heart, kidney, and urinary bladder express MTR mRNA. Specifically, VTR mRNA in the pelvic patch or MTR mRNA in the dorsal skin is present at elevated levels in the skin. Characteristic distribution of VTR and MTR on osmoregulating organs indicates the ligands for these receptors would mediate a variety of functions. Further, the distribution of VTR in the skin would make the regional difference on cutaneous water absorption in response to VT in the Japanese tree frog.

  19. Tree and stand water fluxes of hybrid poplar clone (Populus nigra x P. maximowiczii) in short rotation coppice culture

    NASA Astrophysics Data System (ADS)

    Fischer, M.; Trnka, M.; Kucera, J.; Zalud, Z.

    2010-09-01

    This study reports on evapotranspiration and tree water use in short rotation coppice culture of hybrid poplar (Populus nigra x P. maximowiczii) for biomass energy in the Czech Republic. The high density poplar plantation (10 000 trees per ha) was established in 2003 on arable land in Czech-Moravian Highland (49°32´ N, 16°15´ E, 530 m a.s.l.) and has been coppiced in rotation period of 7 years. Firstly, evapotranspiration of the stand has been estimated by applying the Bowen ratio-energy budget method, which is considered as reliable, robust, quite simple and inexpensive technique with comparable results to eddy covariance and lysimeters. The gaps in evapotranspiration diurnal patterns caused by limitation of the bowen ratio method were filled with simple linear regression model based on relation between potential and actual evapotranspiration with regard to soil water availability and leaf area index and thus the daily, monthly and seasonal totals could be calculated. The amount of evapotranspiration during the growing season 2009 (1 March - 31 October) was 593 mm with highest monthly total 116 mm in June. Mean daily water loss over the season reached 2.43 mm per day. During the hot summer day, the maximal value 5.73 mm per day, which presented 89 % of potential evapotranspiration calculated by Penman equation, was recorded with a peak rate 0.94 mm per hour. Secondly, the transpiration was measured by sap flow tissue heat balance techniques on four individual trees with greatest stem diameters (11 - 12 cm d.b.h.) and height of 12 - 12.5 m. Relatively high transpiration values by the poplars were found during the measured part of growing season (18 June - 31 October), with maximum and mean daily transpiration of 44.41 dm3 and 16.69 dm3 per day, respectively. The seasonal transpiration of the most vigorous from the investigated individuals amounted 2542 dm3. Because in this study we didńt evaluate the transpiration of thinner trees (technical features of sap

  20. Mechanochemical modification of natural rubber

    NASA Astrophysics Data System (ADS)

    Mikhaylov, I. A.; Sukhareva, K. V.; Andriasyan, Yu. O.; Popov, A. A.; Vorontsov, N. V.

    2016-11-01

    Thermomechanochemical changes of SVR 3L natural rubber after the treatment in the internal rubber mixer in the self-heating mode were studied. The effect of the molecular mass and content of the gel fraction of natural rubber is shown. Properties of rubber compounds and vulcanized rubber are presented. Taking into account modern requirements, a new alternative technology of obtaining halogenated elastomers based on the solid-phase (mechanochemical) halide modification is created. New halogen-containing natural rubber produced by this technology proves themselves in the conditions of rubber production. New fluorinated natural rubber produced by this technology proves themselves in the conditions of rubber production.

  1. Nonaqueous ozonation of vulcanized rubber

    DOEpatents

    Serkiz, Steven M.

    1999-01-01

    A process and resulting product is provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  2. Nonaqueous ozonation of vulcanized rubber

    SciTech Connect

    Serkiz, S.M.

    1999-12-07

    A process and resulting product are provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  3. Effects of forests, roads and mistletoe on bird diversity in monoculture rubber plantations.

    PubMed

    Sreekar, Rachakonda; Huang, Guohualing; Yasuda, Mika; Quan, Rui-Chang; Goodale, Eben; Corlett, Richard T; Tomlinson, Kyle W

    2016-02-23

    Rising global demand for natural rubber is expanding monoculture rubber (Hevea brasilensis) at the expense of natural forests in the Old World tropics. Conversion of forests into rubber plantations has a devastating impact on biodiversity and we have yet to identify management strategies that can mitigate this. We determined the life-history traits that best predict bird species occurrence in rubber plantations in SW China and investigated the effects of surrounding forest cover and distance to roads on bird diversity. Mistletoes provide nectar and fruit resources in rubber so we examined mistletoe densities and the relationship with forest cover and rubber tree diameter. In rubber plantations, we recorded less than half of all bird species extant in the surrounding area. Birds with wider habitat breadths and low conservation value had a higher probability of occurrence. Species richness and diversity increased logarithmically with surrounding forest cover, but roads had little effect. Mistletoe density increased exponentially with rubber tree diameters, but was unrelated to forest cover. To maximize bird diversity in rubber-dominated landscapes it is therefore necessary to preserve as much forest as possible, construct roads through plantations and not forest, and retain some large rubber trees with mistletoes during crop rotations.

  4. Effects of forests, roads and mistletoe on bird diversity in monoculture rubber plantations

    NASA Astrophysics Data System (ADS)

    Sreekar, Rachakonda; Huang, Guohualing; Yasuda, Mika; Quan, Rui-Chang; Goodale, Eben; Corlett, Richard T.; Tomlinson, Kyle W.

    2016-02-01

    Rising global demand for natural rubber is expanding monoculture rubber (Hevea brasilensis) at the expense of natural forests in the Old World tropics. Conversion of forests into rubber plantations has a devastating impact on biodiversity and we have yet to identify management strategies that can mitigate this. We determined the life-history traits that best predict bird species occurrence in rubber plantations in SW China and investigated the effects of surrounding forest cover and distance to roads on bird diversity. Mistletoes provide nectar and fruit resources in rubber so we examined mistletoe densities and the relationship with forest cover and rubber tree diameter. In rubber plantations, we recorded less than half of all bird species extant in the surrounding area. Birds with wider habitat breadths and low conservation value had a higher probability of occurrence. Species richness and diversity increased logarithmically with surrounding forest cover, but roads had little effect. Mistletoe density increased exponentially with rubber tree diameters, but was unrelated to forest cover. To maximize bird diversity in rubber-dominated landscapes it is therefore necessary to preserve as much forest as possible, construct roads through plantations and not forest, and retain some large rubber trees with mistletoes during crop rotations.

  5. Effects of forests, roads and mistletoe on bird diversity in monoculture rubber plantations

    PubMed Central

    Sreekar, Rachakonda; Huang, Guohualing; Yasuda, Mika; Quan, Rui-Chang; Goodale, Eben; Corlett, Richard T.; Tomlinson, Kyle W.

    2016-01-01

    Rising global demand for natural rubber is expanding monoculture rubber (Hevea brasilensis) at the expense of natural forests in the Old World tropics. Conversion of forests into rubber plantations has a devastating impact on biodiversity and we have yet to identify management strategies that can mitigate this. We determined the life-history traits that best predict bird species occurrence in rubber plantations in SW China and investigated the effects of surrounding forest cover and distance to roads on bird diversity. Mistletoes provide nectar and fruit resources in rubber so we examined mistletoe densities and the relationship with forest cover and rubber tree diameter. In rubber plantations, we recorded less than half of all bird species extant in the surrounding area. Birds with wider habitat breadths and low conservation value had a higher probability of occurrence. Species richness and diversity increased logarithmically with surrounding forest cover, but roads had little effect. Mistletoe density increased exponentially with rubber tree diameters, but was unrelated to forest cover. To maximize bird diversity in rubber-dominated landscapes it is therefore necessary to preserve as much forest as possible, construct roads through plantations and not forest, and retain some large rubber trees with mistletoes during crop rotations. PMID:26903032

  6. Rubberized asphalt emulsion

    SciTech Connect

    Wilkes, E.

    1986-09-02

    A method is described of making a rubberized asphalt composition which comprises the steps of: (a) combining asphalt with a hydrocarbon oil having a flash point of 300/sup 0/F. or more to provide a homogenous asphalt-oil mixture or solution, (b) then combining the asphalt-oil mixture with a particulate rubber at a temperature sufficient to provide a homogenous asphalt-rubber-oil gel, and (c) emulsifying the asphalt-rubber-oil gel by passing the gel, water, and an emulsifying agent through a colloid mill to provide an emulsion.

  7. Thermodynamics of Rubber Elasticity

    NASA Astrophysics Data System (ADS)

    Pellicer, J.; Manzanares, J. A.; Zúñiga, J.; Utrillas, P.; Fernández, J.

    2001-02-01

    A thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state. The behavior of the rubber band is compared with both that of an ideal elastomer and that of an ideal gas, considering the generalized Joule's law as the ideality criterion. First, the thermal expansion of rubber at constant stress and the change in the stress with temperature at constant length are described. Thermoelastic inversion is then considered, and the experimental observations are easily rationalized. Finally, the temperature changes observed in the adiabatic stretching of a rubber band are evaluated from the decrease of entropy with length.

  8. Rubber friction directional asymmetry

    NASA Astrophysics Data System (ADS)

    Tiwari, A.; Dorogin, L.; Steenwyk, B.; Warhadpande, A.; Motamedi, M.; Fortunato, G.; Ciaravola, V.; Persson, B. N. J.

    2016-12-01

    In rubber friction studies it is usually assumed that the friction force does not depend on the sliding direction, unless the substrate has anisotropic properties, like a steel surface grinded in one direction. Here we will present experimental results for rubber friction, where we observe a strong asymmetry between forward and backward sliding, where forward and backward refer to the run-in direction of the rubber block. The observed effect could be very important in tire applications, where directional properties of the rubber friction could be induced during braking.

  9. Influence of Rubber Size on Properties of Crumb Rubber Mortars

    PubMed Central

    Yu, Yong; Zhu, Han

    2016-01-01

    Studies on the properties and applications of rubber cement-based materials are well documented. The sizes of rubbers used in these materials varied. However, information about the effects of rubber size on the properties of rubber cement-based materials, especially pore structure, mechanical strengths, and drying shrinkage properties, remains limited. Three groups of rubber with major particle sizes of 2–4 mm, 1–3 mm, and 0–2 mm were selected in this study. This paper presents experimental studies on the effects of rubber size on the consistency, fresh density, pore structure, mechanical properties, and drying shrinkage properties of crumb rubber mortars (CRMs). Results demonstrated that the consistency and fresh density of CRMs decreased with the rubber size. As to the pore structure, the total pore volume increased with the decrease of the rubber size. By contrast, the influence of the rubber size on the mesopore (<50 nm) volume is not as significant as that of the rubber content. The mechanical properties of CRMs decreased with the rubber size. Low rubber stiffness and large pore volumes, especially those of small sized rubbers, contribute to the reduction of CRMs strength. The drying shrinkage of CRM increases as the rubber size decreases. The influences of rubber size on capillary tension are not significant. Thus, the shrinkage increases with the decrease of rubber size mainly because of its function in the deformation modulus reduction of CRMs. PMID:28773649

  10. Influence of Rubber Size on Properties of Crumb Rubber Mortars.

    PubMed

    Yu, Yong; Zhu, Han

    2016-06-29

    Studies on the properties and applications of rubber cement-based materials are well documented. The sizes of rubbers used in these materials varied. However, information about the effects of rubber size on the properties of rubber cement-based materials, especially pore structure, mechanical strengths, and drying shrinkage properties, remains limited. Three groups of rubber with major particle sizes of 2-4 mm, 1-3 mm, and 0-2 mm were selected in this study. This paper presents experimental studies on the effects of rubber size on the consistency, fresh density, pore structure, mechanical properties, and drying shrinkage properties of crumb rubber mortars (CRMs). Results demonstrated that the consistency and fresh density of CRMs decreased with the rubber size. As to the pore structure, the total pore volume increased with the decrease of the rubber size. By contrast, the influence of the rubber size on the mesopore (<50 nm) volume is not as significant as that of the rubber content. The mechanical properties of CRMs decreased with the rubber size. Low rubber stiffness and large pore volumes, especially those of small sized rubbers, contribute to the reduction of CRMs strength. The drying shrinkage of CRM increases as the rubber size decreases. The influences of rubber size on capillary tension are not significant. Thus, the shrinkage increases with the decrease of rubber size mainly because of its function in the deformation modulus reduction of CRMs.

  11. Rubber Band Science

    ERIC Educational Resources Information Center

    Cowens, John

    2005-01-01

    Not only are rubber bands great for binding objects together, but they can be used in a simple science experiment that involves predicting, problem solving, measuring, graphing, and experimenting. In this article, the author describes how rubber bands can be used to teach the force of mass.

  12. Nitrosamines and rubber.

    PubMed

    Spiegelhalder, B; Preussmann, R

    1982-01-01

    Occupational exposure to N-nitrosamines in the rubber industry was first reported by Fajen et al. (1979). In order to study the origin and formation of nitrosamines in this industry, chemicals and industrial products, as well as the air in various working areas, were analysed (Spiegelhalder et al., 1980). All chemicals used for rubber compounding contain nitrosamines if they are derivatives of secondary amines; e.g., tetramethylthiurame, zinc-diethyldithiocarbamate or N-oxydiethylene benzothiazolylsulfenamide. All rubber products containing these dialkyl amine derivatives exhibited considerable levels of the corresponding nitrosamines. Accordingly, variable concentrations of airborne nitrosamines could be detected at places where rubber products are manufactured or stored. The nitrosamines found correspond to the compounded chemicals. The original nitrosamine level in rubber chemicals is not high enough to explain the amounts found in rubber products and in air, so that additional nitrosation must occur. The responsible nitrosating agents are described. Preliminary results show that, in most cases, the elimination of nitrosating agents or the use of different rubber chemicals can drastically reduce nitrosamine levels in rubber products and in working areas.

  13. Rubber Band Science

    ERIC Educational Resources Information Center

    Cowens, John

    2005-01-01

    Not only are rubber bands great for binding objects together, but they can be used in a simple science experiment that involves predicting, problem solving, measuring, graphing, and experimenting. In this article, the author describes how rubber bands can be used to teach the force of mass.

  14. Natural rubber biosynthesis in plants: rubber transferase.

    PubMed

    Cornish, Katrina; Xie, Wenshuang

    2012-01-01

    Rubber biosynthesis in plants is a fascinating biochemical system, which evolved at the dawn of the dicotyledoneae and is present in at least four of the dictolydonous superorders. Rubber biosynthesis is catalyzed by a membrane complex in a monolayer membrane envelope, requires two distinct substrates and a divalent cation cofactor, and produces a high-molecular-weight isoprenoid polymer. A solid understanding of this system underpins valuable papers in the literature. However, the published literature is rife with unreliable reports in which the investigators have fallen into traps created by the current incomplete understanding of the biochemistry of rubber synthesis. In this chapter, we attempt to guide both new and more established researchers around these pitfalls.

  15. Failure studies on rubber and rubber composites

    NASA Astrophysics Data System (ADS)

    Tao, Zhenghong

    A research study has been conducted to investigate selected failure processes in rubber and rubbery composites. Specific failure modes and materials considered included mechanical tearing of rubber-coated fabrics and mechanical/thermal fatigue of carbon black-filled elastomers. Experimental efforts developed novel evaluation techniques that were used to access failure resistance of the materials, as well as to elucidate molecular structure/physical properties relationships. Results are presented in multi-monograph format consisting of a series of four interdependent papers published in peer-reviewed journals. The first monograph measures the tear resistance of a series of polyester fabrics, of controlled fill-yarn size, coated with a compounded butyl rubber resin. A constrained trouser tear test is used to quantify the role of yarn mobility on crack-tip development and the resultant tear strength. As the area around a propagating crack is constrained, tear strength decreases by several orders of magnitude, indicating that the ability of the composite structure to dissipate energy away from the crack tip contributes more to tear resistance than the intrinsic strength of the concomitant materials. Monograph number two continues the work of the first by developing a novel cutting technique to monitor the role of the fiber/rubber interphase during tear propagation. This approach was applied to five different elastomers coated onto one of the polyester yarns. These data show a threefold increase in strength is possible by proper optimization of the fiber/rubber bond. In the third monograph, five different rubber bushing compounds were evaluated for mechanical/thermal fatigue resistance. Samples were dynamically excited in combined compression and shear loadings using a specially designed test fixture. Results indicated that heat build-up was a major contributing factor to the eventual failure of the materials via a complex fracture mechanism, with epoxidized natural

  16. Seasonal Patterns of Fine Root Production and Turnover in a Mature Rubber Tree (Hevea brasiliensis Müll. Arg.) Stand- Differentiation with Soil Depth and Implications for Soil Carbon Stocks

    PubMed Central

    Maeght, Jean-Luc; Gonkhamdee, Santimaitree; Clément, Corentin; Isarangkool Na Ayutthaya, Supat; Stokes, Alexia; Pierret, Alain

    2015-01-01

    Fine root dynamics is a main driver of soil carbon stocks, particularly in tropical forests, yet major uncertainties still surround estimates of fine root production and turnover. This lack of knowledge is largely due to the fact that studying root dynamics in situ, particularly deep in the soil, remains highly challenging. We explored the interactions between fine root dynamics, soil depth, and rainfall in mature rubber trees (Hevea brasiliensis Müll. Arg.) exposed to sub-optimal edaphic and climatic conditions. A root observation access well was installed in northern Thailand to monitor root dynamics along a 4.5 m deep soil profile. Image-based measurements of root elongation and lifespan of individual roots were carried out at monthly intervals over 3 years. Soil depth was found to have a significant effect on root turnover. Surprisingly, root turnover increased with soil depth and root half-life was 16, 6–8, and only 4 months at 0.5, 1.0, 2.5, and 3.0 m deep, respectively (with the exception of roots at 4.5 m which had a half-life similar to that found between depths of 1.0 and 2.5 m). Within the first two meters of the soil profile, the highest rates of root emergence occurred about 3 months after the onset of the rainy season, while deeper in the soil, root emergence was not linked to the rainfall pattern. Root emergence was limited during leaf flushing (between March and May), particularly within the first two meters of the profile. Between soil depths of 0.5 and 2.0 m, root mortality appeared independent of variations in root emergence, but below 2.0 m, peaks in root emergence and death were synchronized. Shallow parts of the root system were more responsive to rainfall than their deeper counterparts. Increased root emergence in deep soil toward the onset of the dry season could correspond to a drought acclimation mechanism, with the relative importance of deep water capture increasing once rainfall ceased. The considerable soil depth regularly explored

  17. Equipment for shredding rubber scrap

    SciTech Connect

    Rozhkov, V.F.; Golikov, V.N.; Kurglov, V.I.; Cherepkova, R.V.

    1987-07-01

    The authors describe a range of machines developed for shredding rubber scrap and discarded rubber articles into crumbs. Technical characteristics of the machine for shredding vulcanized pressed-rubber parts, used rubber articles and scrap from the shoe industry are presented. A machine for shredding rubber scrap from plants making rubber products and from the shoe industry is shown, as is one for producing rubber crumbs from the scrap during the roughing of tires. Another machine is examined which cuts tires with metallic cords.

  18. Multilayer graphene rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

    2016-05-01

    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  19. A study of protein and amino acids in guayule natural rubber

    USDA-ARS?s Scientific Manuscript database

    Natural rubber (NR) from Hevea brasiliensis (the Hevea rubber tree) is a critical agricultural material vital to United States industry, medicine, and defense, yet the country is dependent on NR imports to meet domestic needs. Parthenium argentatum (guayule), a woody desert shrub indigenous to the U...

  20. Micro-organisms in latex and natural rubber coagula of Hevea brasiliensis and their impact on rubber composition, structure and properties.

    PubMed

    Salomez, M; Subileau, M; Intapun, J; Bonfils, F; Sainte-Beuve, J; Vaysse, L; Dubreucq, E

    2014-10-01

    Natural rubber, produced by coagulation of the latex from the tree Hevea brasiliensis, is an important biopolymer used in many applications for its outstanding properties. Besides polyisoprene, latex is rich in many nonisoprene components such as carbohydrates, proteins and lipids and thereby constitutes a favourable medium for the development of micro-organisms. The fresh rubber coagula obtained by latex coagulation are not immediately processed, allowing the development of various microbial communities. The time period between tree tapping and coagula processing is called maturation, during which an evolution of the properties of the corresponding dry natural rubber occurs. This evolution is partly related to the activity of micro-organisms and to the modification of the biochemical composition. This review synthesizes the current knowledge on microbial populations in latex and natural rubber coagula of H. brasiliensis and the changes they induce on the biochemistry and technical properties of natural rubber during maturation.

  1. Ericameria Nauseosa (rubber rabbitbrush): a complementary rubber feedstock to augment the guayule rubber production stream

    USDA-ARS?s Scientific Manuscript database

    Ericameria nauseosa (rubber rabbitbrush) is a highly prolific desert shrub that produces high quality natural rubber. Over the past several years we have investigated rabbitbrush’s potential as a commercial rubber feedstock. Like guayule, rabbitbrush produces natural rubber within its bark tissues a...

  2. Rubberized, Brominated Epoxies

    NASA Technical Reports Server (NTRS)

    Gilwee, W.; Kourtides, D.; Parker, J.; Nir, Z.

    1985-01-01

    Graphite/epoxy composite materials made with resins containing bromine and rubber additives. New composites tougher and more resistant to fire. Flame resistance increased by introducing bromine via commercial brominated flame-retartant polymeric additives.

  3. Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants.

    PubMed

    Wu, Junen; Liu, Wenjie; Chen, Chunfeng

    2016-01-19

    Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ(18)O, and δ(13)C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ(18)O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ(13)C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer.

  4. Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants

    PubMed Central

    Wu, Junen; Liu, Wenjie; Chen, Chunfeng

    2016-01-01

    Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ18O, and δ13C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ18O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ13C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer. PMID:26781071

  5. Cloning and characterization of HbMT2a, a metallothionein gene from Hevea brasiliensis Muell. Arg differently responds to abiotic stress and heavy metals.

    PubMed

    Li, Yan; Chen, Yue Yi; Yang, Shu Guang; Tian, Wei Min

    2015-05-22

    Metallothioneins (MTs) are of low molecular mass, cysteine-rich proteins. They play an important role in the detoxification of heavy metals and homeostasis of intracellular metal ions, and protecting against intracellular oxidative damages. In this study a full-length cDNA of type 2 plant metallothioneins, HbMT2a, was isolated from 25 mM Polyethyleneglycol (PEG) stressed leaves of Hevea brasiliensis by RACE. The HbMT2a was 372bp in length and had a 237bp open reading frame (ORF) encoding for a protein of 78 amino acid residues with molecular mass of 7.772 kDa. The expression of HbMT2a in the detached leaves of rubber tree clone RY7-33-97 was up-regulated by Me-JA, ABA, PEG, H2O2, Cu(2+) and Zn(2+), but down-regulated by water. The role of HbMT2a protein in protecting against metal toxicity was demonstrated in vitro. PET-28a-HbMT2-beared Escherichia coli. Differential expression of HbMT2a upon treatment with 10 °C was observed in the detached leaves of rubber tree clone 93-114 which is cold-resistant and Reken501 which is cold-sensitive. The expression patterns of HbMT2a in the two rubber tree clones may be ascribed to a change in the level of endogenous H2O2.

  6. Microwave treatment of vulcanized rubber

    DOEpatents

    Wicks, George G.; Schulz, Rebecca L.; Clark, David E.; Folz, Diane C.

    2002-07-16

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds broken by microwave radiation. The direct application of microwaves in combination with uniform heating of the crumb rubber renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger particle sizes and/or loading levels of the treated crumb rubber can be used in new rubber mixtures to produce recycled composite products with good properties.

  7. Evapotranspiration of rubber ( Hevea brasiliensis ) cultivated at two plantation sites in Southeast Asia: RUBBER EVAPOTRANSPIRATION IN SE ASIA

    SciTech Connect

    Giambelluca, Thomas W.; Mudd, Ryan G.; Liu, Wen; Ziegler, Alan D.; Kobayashi, Nakako; Kumagai, Tomo'omi; Miyazawa, Yoshiyuki; Lim, Tiva Khan; Huang, Maoyi; Fox, Jefferson; Yin, Song; Mak, Sophea Veasna; Kasemsap, Poonpipope

    2016-02-01

    The expansion of rubber (Hevea brasiliensis) cultivation to higher latitudes and higher elevations in southeast Asia is part of a dramatic shift in the direction of rural land cover change in the region toward more tree covered landscapes. To investigate the possible effects of increasing rubber cultivation in the region on ecosystem services including water cycling, eddy covariance towers were established to measure ecosystem fluxes within two rubber plantations, one each in Bueng Kan, northeastern Thailand, and Kampong Cham, central Cambodia. The results show that evapotranspiration (ET) at both sites is strongly related to variations in available energy and leaf area, and moderately controlled by soil moisture. Measured mean annual ET was 1128 and 1272 mm for the Thailand and Cambodia sites, respectively. After adjustment for energy closure, mean annual was estimated to be 1211 and 1459 mm yr at the Thailand and Cambodia sites, respectively. Based on these estimates and that of another site in Xishuangbanna, southwestern China, it appears that of rubber is higher than that of other tree dominated land covers in the region, including forest. While measurements by others in non rubber tropical ecosystems indicate that at high net radiation sites is at most only slightly higher than for sites with lower net radiation, mean annual rubber increases strongl with increasing net radiation across the three available rubber plantation observation sites. With the continued expansion of tree dominated land covers, including rubber cultivation, in southeast Asia, the possible association between commercially viable, fast growing tree crop species Giambelluca et al. Evapotranspiration of rubber (Havea brasiliensis) cultivated at two sites in southeast Asia and their relatively high water use raises concerns about potential effects on water and food security.

  8. Dermatitis in rubber manufacturing industries

    SciTech Connect

    White, I.R.

    1988-01-01

    This review describes the history of rubber technology and the manufacturing techniques used in rubber manufacturing industries. The important aspects of the acquisition of allergic and irritant contact dermatitis within the industry are presented for the reader.

  9. Biodesulfurization of rubber materials

    SciTech Connect

    Torma, A.E. ); Raghavan, D. . Dept. of Materials Science and Engineering)

    1990-01-01

    One of the most challenging problems in municipal waste treatment is the recycling of polymeric waste materials. The present study has demonstrated the applicability of biotechnological principles in the desulfurization of rubber using shake flask and Warburg respirometric techniques. In terms of oxygen uptake and specific rate of oxygen uptake, it was found that the mixed culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans was more efficient in this process than the individual pure cultures of these bacteria. Furthermore, the mixed cultures resulted in ten times higher sulfur removals from rubber relative to those of sterile controls. Additional studies are needed to elucidate the mechanisms of biodesulfurization of rubber. It is expected that the development of this process may provide a solution to recycling of car tire materials. 32 refs., 4 figs., 3 tabs.

  10. Taxonomic revision and phylogenetic analyses of rubber powdery mildew fungi.

    PubMed

    Liyanage, K K; Khan, Sehroon; Brooks, Siraprapa; Mortimer, Peter E; Karunarathna, Samantha C; Xu, Jianchu; Hyde, Kevin D

    2017-04-01

    Powdery mildew is a fungal disease that infects a wide range of plants, including rubber trees, which results in a reduction of latex yields of up to 45%. The causal agent of powdery mildew of rubber was first described as Oidium heveae, but later morpho-molecular research suggested that in the past, O. heveae has been confused with Erysiphe quercicola. However, it is still under debate whether the causal agent should be classified as a species of the genus Erysiphe emend. or Golovinomyces and Podosphaera, respectively. Therefore, the aim of this study was to undertake the morpho-molecular characterization of powdery mildew species associated with rubber trees, thus resolving these taxonomic issues. Morphological observation under light and scanning electron microscopes (SEM) clearly identified two morphotypes of the rubber powdery mildew. With the support of morphological and phylogenetic data, one of the two morphotypes was identified as the asexual morph of E. quercicola, while the second morphotype is still insufficiently known and according to the morphological results obtained we assume that it might belong to the genus Golovinomyces. More collections and additional molecular data are required for final conclusions regarding the exact taxonomic position of the second morphotype of rubber powdery mildew and its relation to the name O. heveae. The haplotype analysis identified eight haplotype groups of E. quercicola indicating the high genetic diversity of the species.

  11. Recycling rubber products sensibly

    SciTech Connect

    Fesus, E.M.; Eggleton, R.W.

    1991-03-01

    This article examines processes for surface treating ground rubber from tires and other sources to enhance its ability to chemically bond with an uncured elastomer matrix during vulcanization. The topics discussed are environmental effects, processing and physical and chemical properties, mesh size, compounding, loading study, mineral fillers, and applications.

  12. Cloning and Expression Analysis of One Gamma-Glutamylcysteine Synthetase Gene (Hbγ-ECS1) in Latex Production in Hevea brasiliensis

    PubMed Central

    Fang, Wei; Qiao, Luo Shi; Ming, Wu; Jian, Qiu; Feng, Yang Wen; Hua, Gao Hong; Zhou, Xiao Xian

    2016-01-01

    Rubber tree is a major commercial source of natural rubber. Latex coagulation is delayed by thiols, which belong to the important type of antioxidants in laticifer submembrane, and is composed of glutathione (GSH), cysteine, and methionine. The rate-limiting enzyme, γ-ECS, plays an important role in regulating the biosynthesis of glutathione under any environment conditions. To understand the relation between γ-ECS and thiols and to correlate latex flow with one-time tapping and continuous tapping, we cloned and derived the full length of one γ-ECS from rubber tree latex (Hbγ-ECS1). According to qPCR analysis, the expression levels of Hbγ-ECS1 were induced by tapping and Ethrel stimulation, and the expression was related to thiols content in the latex. Continuous tapping induced injury, and the expression of HbγECS1 increased with routine tapping and Ethrel-stimulation tapping (more intensive tapping). According to expression in long-term flowing latex, the gene was related to the duration of latex flow. HbγECS1 was expressed in E. coli Rosetta using pET-sumo as an expression vector and the recombinant enzyme was purified; then we achieved 0.827 U/mg specific activity and about 66 kDa molecular weight. The present study can help us understand the complex role of Hbγ-ECS in thiols biosynthesis, which is influenced by tapping. PMID:27419133

  13. Cloning and Expression Analysis of One Gamma-Glutamylcysteine Synthetase Gene (Hbγ-ECS1) in Latex Production in Hevea brasiliensis.

    PubMed

    Fang, Wei; Qiao, Luo Shi; Ming, Wu; Jian, Qiu; Feng, Yang Wen; Hua, Gao Hong; Zhou, Xiao Xian

    2016-01-01

    Rubber tree is a major commercial source of natural rubber. Latex coagulation is delayed by thiols, which belong to the important type of antioxidants in laticifer submembrane, and is composed of glutathione (GSH), cysteine, and methionine. The rate-limiting enzyme, γ-ECS, plays an important role in regulating the biosynthesis of glutathione under any environment conditions. To understand the relation between γ-ECS and thiols and to correlate latex flow with one-time tapping and continuous tapping, we cloned and derived the full length of one γ-ECS from rubber tree latex (Hbγ-ECS1). According to qPCR analysis, the expression levels of Hbγ-ECS1 were induced by tapping and Ethrel stimulation, and the expression was related to thiols content in the latex. Continuous tapping induced injury, and the expression of HbγECS1 increased with routine tapping and Ethrel-stimulation tapping (more intensive tapping). According to expression in long-term flowing latex, the gene was related to the duration of latex flow. HbγECS1 was expressed in E. coli Rosetta using pET-sumo as an expression vector and the recombinant enzyme was purified; then we achieved 0.827 U/mg specific activity and about 66 kDa molecular weight. The present study can help us understand the complex role of Hbγ-ECS in thiols biosynthesis, which is influenced by tapping.

  14. Transpiration characteristics of a rubber plantation in central Cambodia.

    PubMed

    Kobayashi, Nakako; Kumagai, Tomo'omi; Miyazawa, Yoshiyuki; Matsumoto, Kazuho; Tateishi, Makiko; Lim, Tiva K; Mudd, Ryan G; Ziegler, Alan D; Giambelluca, Thomas W; Yin, Song

    2014-03-01

    The rapid and widespread expansion of rubber plantations in Southeast Asia necessitates a greater understanding of tree physiology and the impacts of water consumption on local hydrology. Sap flow measurements were used to study the intra- and inter-annual variations in transpiration rate (Et) in a rubber stand in the low-elevation plain of central Cambodia. Mean stand sap flux density (JS) indicates that rubber trees actively transpire in the rainy season, but become inactive in the dry season. A sharp, brief drop in JS occurred simultaneously with leaf shedding in the middle of the dry season in January. Although the annual maxima of JS were approximately the same in the two study years, the maximum daily stand Et of ∼2.0 mm day(-1) in 2010 increased to ∼2.4 mm day(-1) in 2011. Canopy-level stomatal response was well explained by changes in solar radiation, vapor pressure deficit, soil moisture availability, leaf area, and stem diameter. Rubber trees had a relatively small potential to transpire at the beginning of the study period, compared with average diffuse-porous species. After 2 years of growth in stem diameter, transpiration potential was comparable to other species. The sensitivity of canopy conductance (gc) to atmospheric drought indicates isohydric behavior of rubber trees. Modeling also predicted a relatively small sensitivity of gc to the soil moisture deficit and a rapid decrease in gc under extreme drought conditions. However, annual observations suggest the possibility of a change in leaf characteristics with tree maturity and/or initiation of latex tapping. The estimated annual stand Et was 469 mm year(-1) in 2010, increasing to 658 mm year(-1) in 2011. Diagnostic analysis using the derived gc model showed that inter-annual change in stand Et in the rapidly growing young rubber stand was determined mainly by tree growth rate, not by differences in air and soil variables in the surrounding environment. Future research should focus on the

  15. Logging damage using an individual tree selection practice in Appalachian hardwood stands

    Treesearch

    Neil I. Lamson; H. Clay Smith; Gary W. Miller

    1985-01-01

    Four West Virginia hardwood stands, managed using individual-tree selection for the past 30 years, were examined after the third and, in one instance, the fourth periodic harvest to determine the severity of logging damage. On existing skid roads, trees were removed with a rubber-tired skidder or a crawler tractor with a rubber-tired arch. Logging damage reduced...

  16. Crumb rubber feasibility report

    SciTech Connect

    1985-11-01

    The Cumberland County supply region generates approximately 58,000 tons of scrap tires each year, equivalent to 45,000 tons of rubber after processing. Approximately 8,000 tons per year are in concentrated locations and can be easily collected. The costs of collection for the remainder vary significantly. Given current markets, economically feasible processes (ambient technology) can reprocess approximately 65 to 75 percent of the 37,000 tons into a marketable product. A processing plant sized for this supply would process 120 tons per day, a viable plant by industry standards. The end uses for whole tires constitute a negligible market, aside from the retreader market. Crumbed rubber is the major development efforts, there are potentially large opportunities in North Carolina.

  17. Pityophthorus orarius Bright (Coleoptera: Scolytidae) in a northern California Douglas-fir seed orchard: effect of clone, tree vigor, and cone crop on rate of attack

    Treesearch

    Nancy G. Rappaport; David L. Wood

    1994-01-01

    The geographic range of the Douglas-fir twig beetle, Pityophthorus orarius Bright, was extended beyond the original provenance of southern British Columbia to northern California. A survey of 457 Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] trees in 1985 revealed that those with heavy cone crops were more likely to be...

  18. Statistical inference for classification of RRIM clone series using near IR reflectance properties

    NASA Astrophysics Data System (ADS)

    Ismail, Faridatul Aima; Madzhi, Nina Korlina; Hashim, Hadzli; Abdullah, Noor Ezan; Khairuzzaman, Noor Aishah; Azmi, Azrie Faris Mohd; Sampian, Ahmad Faiz Mohd; Harun, Muhammad Hafiz

    2015-08-01

    RRIM clone is a rubber breeding series produced by RRIM (Rubber Research Institute of Malaysia) through "rubber breeding program" to improve latex yield and producing clones attractive to farmers. The objective of this work is to analyse measurement of optical sensing device on latex of selected clone series. The device using transmitting NIR properties and its reflectance is converted in terms of voltage. The obtained reflectance index value via voltage was analyzed using statistical technique in order to find out the discrimination among the clones. From the statistical results using error plots and one-way ANOVA test, there is an overwhelming evidence showing discrimination of RRIM 2002, RRIM 2007 and RRIM 3001 clone series with p value = 0.000. RRIM 2008 cannot be discriminated with RRIM 2014; however both of these groups are distinct from the other clones.

  19. 69 FR 61403 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2004-10-18

    ... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION... on polychloroprene rubber from Japan. SUMMARY: The Commission hereby gives notice that it will...)) to determine whether revocation of the antidumping finding on polychloroprene rubber from Japan...

  20. Cloning cattle.

    PubMed

    Oback, B; Wells, D N

    2003-01-01

    Over the past six years, hundreds of apparently normal calves have been cloned worldwide from bovine somatic donor cells. However, these surviving animals represent less than 5% of all cloned embryos transferred into recipient cows. Most of the remaining 95% die at various stages of development from a predictable pattern of placental and fetal abnormalities, collectively referred to as the "cloning-syndrome." The low efficiency seriously limits commercial applicability and ethical acceptance of somatic cloning and enforces the development of improved cloning methods. In this paper, we describe our current standard operating procedure (SOP) for cattle cloning using zona-free nuclear transfer. Following this SOP, the output of viable and healthy calves at weaning is about 9% of embryos transferred. Better standardization of cloning protocols across and within research groups is needed to separate technical from biological factors underlying low cloning efficiency.

  1. QENS investigation of filled rubbers

    NASA Astrophysics Data System (ADS)

    Triolo, A.; Lo Celso, F.; Negroni, F.; Arrighi, V.; Qian, H.; Lechner, R. E.; Desmedt, A.; Pieper, J.; Frick, B.; Triolo, R.

    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface.

  2. [Cloning - controversies].

    PubMed

    Twardowski, T; Michalska, A

    2001-01-01

    Cloning of the human being is not only highly controversial; in the opinion of the authors it is impossible - we are not able to reproduce human behaviour and character traits. Reproduction through cloning is limited to personal genome resources. The more important is protection of genomic characteristics as private property and taking advantage of cloning for production of the human organs directly or through xenotransplants. In this paper we present the legislation related to cloning in Poland, in the European Union and other countries. We also indicate who and why is interested in cloning.

  3. Rubber composition compatible with hydrazine

    NASA Technical Reports Server (NTRS)

    Repar, J.

    1973-01-01

    Formulation improves compatibility of butyl rubbers with hydrazine while reducing permeation to low levels necessary for prolonged storage in space. This is accomplished by replacing carbon-black filler with inert materials such as hydrated silica or clay. Pressure increases suggest that hydrazine is decomposed only slightly by new type of rubber.

  4. Guayule rubber for South Africa

    SciTech Connect

    Not Available

    1981-06-17

    It is reported that Agtec together with South Africa's Council for Scientific and Industrial Research, is investigating the possibility of large-scale production of guayule. The rubber-yielding shrub grows in semi-arid climates and may be the source of a $35-million natural rubber industry in South Africa.

  5. Productivity of rubber-tired skidders in southern pine forests

    Treesearch

    R. Kluender; D. Lortz; W. McCoy; B. Stokes; J. Klepac

    1997-01-01

    Sixteen stands were harvested at intensities (proportion of basal area removed) ranging from 0.27 to 1.00. Logging contractors used one or two rubber-tired cable and/or grapple skidders. Harvested sites were similar in slope, tree size, and stand composition. Thirteen of the stands had even-aged structures while the other three were uneven-aged. Skidding time per cycle...

  6. Saga of synthetic rubber

    SciTech Connect

    Solo, R.A.

    1980-04-01

    The proposal to establish an Energy Mobilization Board and a synthetic fuels industry is reminiscent of World War II efforts to produce synthetic rubber. To avoid the mistakes made in the earlier effort, Mr. Solo suggests that the synthetic-fuel program should (1) use a more-successful technological development project as a model; (2) commit public funding and not rely on profit-oriented private enterprise; and (3) avoid entrusting social planning to single-purpose entities that have not been sensitive to social values. (DCK)

  7. Down-regulation of small rubber particle protein expression affects integrity of rubber particles and rubber content in Taraxacum brevicorniculatum.

    PubMed

    Hillebrand, Andrea; Post, Janina J; Wurbs, David; Wahler, Daniela; Lenders, Malte; Krzyzanek, Vladislav; Prüfer, Dirk; Gronover, Christian Schulze

    2012-01-01

    The biosynthesis of rubber is thought to take place on the surface of rubber particles in laticifers, highly specialized cells that are present in more than 40 plant families. The small rubber particle protein (SRPP) has been supposed to be involved in rubber biosynthesis, and recently five SRPPs (TbSRPP1-5) were identified in the rubber-producing dandelion species Taraxacum brevicorniculatum. Here, we demonstrate by immunogold labeling that TbSRPPs are localized to rubber particles, and that rubber particles mainly consist of TbSRPP3, 4 and 5 as shown by high-resolution two-dimensional gel electrophoresis and mass spectrometric analysis. We also carried out an RNA-interference approach in transgenic plants to address the function of TbSRPPs in rubber biosynthesis as well as rubber particle morphology and stability. TbSRPP-RNAi transgenic T. brevicorniculatum plants showed a 40-50% reduction in the dry rubber content, but neither the rubber weight average molecular mass nor the polydispersity of the rubber were affected. Although no phenotypical differences to wild-type particles could be observed in vivo, rubber particles from the TbSRPP-RNAi transgenic lines were less stable and tend to rapidly aggregate in expelling latex after wounding of laticifers. Our results prove that TbSRPPs are very crucial for rubber production in T. brevicorniculatum, probably by contributing to a most favourable and stable rubber particle architecture for efficient rubber biosynthesis and eventually storage.

  8. Down-Regulation of Small Rubber Particle Protein Expression Affects Integrity of Rubber Particles and Rubber Content in Taraxacum brevicorniculatum

    PubMed Central

    Hillebrand, Andrea; Post, Janina J.; Wurbs, David; Wahler, Daniela; Lenders, Malte; Krzyzanek, Vladislav; Prüfer, Dirk; Gronover, Christian Schulze

    2012-01-01

    The biosynthesis of rubber is thought to take place on the surface of rubber particles in laticifers, highly specialized cells that are present in more than 40 plant families. The small rubber particle protein (SRPP) has been supposed to be involved in rubber biosynthesis, and recently five SRPPs (TbSRPP1–5) were identified in the rubber-producing dandelion species Taraxacum brevicorniculatum. Here, we demonstrate by immunogold labeling that TbSRPPs are localized to rubber particles, and that rubber particles mainly consist of TbSRPP3, 4 and 5 as shown by high-resolution two-dimensional gel electrophoresis and mass spectrometric analysis. We also carried out an RNA-interference approach in transgenic plants to address the function of TbSRPPs in rubber biosynthesis as well as rubber particle morphology and stability. TbSRPP-RNAi transgenic T. brevicorniculatum plants showed a 40–50% reduction in the dry rubber content, but neither the rubber weight average molecular mass nor the polydispersity of the rubber were affected. Although no phenotypical differences to wild-type particles could be observed in vivo, rubber particles from the TbSRPP-RNAi transgenic lines were less stable and tend to rapidly aggregate in expelling latex after wounding of laticifers. Our results prove that TbSRPPs are very crucial for rubber production in T. brevicorniculatum, probably by contributing to a most favourable and stable rubber particle architecture for efficient rubber biosynthesis and eventually storage. PMID:22911861

  9. Robotically enhanced rubber hand illusion.

    PubMed

    Arata, Jumpei; Hattori, Masashi; Ichikawa, Shohei; Sakaguchi, Masamichi

    2014-01-01

    The rubber hand illusion is a well-known multisensory illusion. In brief, watching a rubber hand being stroked by a paintbrush while one's own unseen hand is synchronously stroked causes the rubber hand to be attributed to one's own body and to "feel like it's my hand." The rubber hand illusion is thought to be triggered by the synchronized tactile stimulation of both the subject's hand and the fake hand. To extend the conventional rubber hand illusion, we introduce robotic technology in the form of a master-slave telemanipulator. The developed one degree-of-freedom master-slave system consists of an exoskeleton master equipped with an optical encoder that is worn on the subject's index finger and a motor-actuated index finger on the rubber hand, which allows the subject to perform unilateral telemanipulation. The moving rubber hand illusion has been studied by several researchers in the past with mechanically connected rigs between the subject's body and the fake limb. The robotic instruments let us investigate the moving rubber hand illusion with less constraints, thus behaving closer to the classic rubber hand illusion. In addition, the temporal delay between the body and the fake limb can be precisely manipulated. The experimental results revealed that the robotic instruments significantly enhance the rubber hand illusion. The time delay is significantly correlated with the effect of the multisensory illusion, and the effect significantly decreased at time delays over 100 ms. These findings can potentially contribute to the investigations of neural mechanisms in the field of neuroscience and of master-slave systems in the field of robotics.

  10. Evapotranspiration of rubber (Hevea brasiliensis) cultivated at two plantation sites in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Giambelluca, Thomas W.; Mudd, Ryan G.; Liu, Wen; Ziegler, Alan D.; Kobayashi, Nakako; Kumagai, Tomo'omi; Miyazawa, Yoshiyuki; Lim, Tiva Khan; Huang, Maoyi; Fox, Jefferson; Yin, Song; Mak, Sophea Veasna; Kasemsap, Poonpipope

    2016-02-01

    To investigate the effects of expanding rubber (Hevea brasiliensis) cultivation on water cycling in Mainland Southeast Asia (MSEA), evapotranspiration (ET) was measured within rubber plantations at Bueng Kan, Thailand, and Kampong Cham, Cambodia. After energy closure adjustment, mean annual rubber ET was 1211 and 1459 mm yr-1 at the Thailand and Cambodia sites, respectively, higher than that of other tree-dominated land covers in the region, including tropical seasonal forest (812-1140 mm yr-1), and savanna (538-1060 mm yr-1). The mean proportion of net radiation used for ET by rubber (0.725) is similar to that of tropical rainforest (0.729) and much higher than that of tropical seasonal forest (0.595) and savanna (0.548). Plant area index (varies with leaf area changes), explains 88.2% and 73.1% of the variance in the ratio of latent energy flux (energy equivalent of ET) to potential latent energy flux (LE/LEpot) for midday rain-free periods at the Thailand and Cambodia sites, respectively. High annual rubber ET results from high late dry season water use, associated with rapid refoliation by this brevideciduous species, facilitated by tapping of deep soil water, and by very high wet season ET, a characteristic of deciduous trees. Spatially, mean annual rubber ET increases strongly with increasing net radiation (Rn) across the three available rubber plantation observation sites, unlike nonrubber tropical ecosystems, which reduce canopy conductance at high Rn sites. High water use by rubber raises concerns about potential effects of continued expansion of tree plantations on water and food security in MSEA.

  11. Chlorinolysis reclaims rubber of waste tires

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.; Tervet, J. H.; Hull, G. G.

    1981-01-01

    Process reclaims rubber and reduces sulfur content by using chlorine gas to oxidize sulfur bonds in preference to other bonds. Rubber does not have poor hysteresis and abrasion resistance like conventionally reclaimed rubber and is suitable for premium radial tires. Chlorinated rubber is less susceptible to swelling by oils and may be used as paint ingredient.

  12. Chlorinolysis reclaims rubber of waste tires

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.; Tervet, J. H.; Hull, G. G.

    1981-01-01

    Process reclaims rubber and reduces sulfur content by using chlorine gas to oxidize sulfur bonds in preference to other bonds. Rubber does not have poor hysteresis and abrasion resistance like conventionally reclaimed rubber and is suitable for premium radial tires. Chlorinated rubber is less susceptible to swelling by oils and may be used as paint ingredient.

  13. Recycling, production and use of reprocessed rubbers

    SciTech Connect

    Klingensmith, B. )

    1991-03-01

    This article examines the various methods used to produce recycled rubber and to compare their characteristics and application. The topics discussed include reclaiming by chemical digestion, devulcanization by the severing of sulfur bonds, ambient temperature and cryogenically ground rubber, processing and mixing of ground rubber, and properties of reclaimed rubbers by reclamation method.

  14. Human Cloning

    DTIC Science & Technology

    2006-07-20

    not believe that noncoital, asexual reproduction , such as cloning, would be considered a fundamental right by the Supreme Court. A ban on human...society by “crossing the boundary from sexual to asexual reproduction , thus approving in principle the genetic manipulation and control of nascent human... reproductive cloning and, by a vote of 10 to 7, a four-year moratorium on cloning for medical research purposes. The ethical issues surrounding reproductive

  15. Seasonal and clonal variations in technological and thermal properties of raw Hevea natural rubber

    USDA-ARS?s Scientific Manuscript database

    This study was undertaken over a ten-month period, under the environmental conditions within the state of Mato Grosso, Brazil, to evaluate the causes of variation in technological and thermal properties of raw natural rubber from different clones of Hevea brasiliensis (GT 1, PR 255, FX 3864 and RRIM...

  16. Widespread occurrence and phylogenetic placement of a soil clone group adds a prominant new branch to the fungal tree of life

    SciTech Connect

    Porter, Terri M.; Schadt, Christopher Warren; Rizvi, L; Martin, Andrew P.; Schmidt, Steven K.; Scott-Denton, Laura; Vilgalys, Rytas; Moncalvo, Jean-Marc

    2008-01-01

    Fungi are one of the most diverse groups of Eukarya and play essential roles in terrestrial ecosystems as decomposers, pathogens and mutualists. This study unifies disparate reports of unclassified fungal sequences from soils of diverse origins and anchors many of them in a well-supported clade of the Ascomycota equivalent to a subphylum. We refer to this clade as Soil Clone Group I (SCGI). We expand the breadth of environments surveyed and develop a taxon-specific primer to amplify 2.4 kbp rDNA fragments directly from soil. Our results also expand the known range of this group from North America to Europe and Australia. The ancient origin of SCGI implies that it may represent an important transitional form among the basal Ascomycota groups. SCGI is unusual because it currently represents the only major fungal lineage known only from sequence data. This is an important contribution towards building a more complete fungal phylogeny and highlights the need for further work to determine the function and biology of SCGI taxa.

  17. Styrene-butadiene rubber/halloysite nanotubes composites modified by epoxidized natural rubber.

    PubMed

    Jia, Zhixin; Luo, Yuanfang; Yang, Shuyan; Du, Mingliang; Guo, Baochun; Jia, Demin

    2011-12-01

    The reinforcement effects of halloysite nanotubes on styrene-butadiene rubber and the modification effect of epoxidized natural rubber on styrene-butadiene rubber/halloysite nanotubes composites were studied. The structure, morphology and properties of styrene-butadiene rubber/halloysite nanotubes composites before and after the incorporation of epoxidized natural rubber were investigated. The results indicated that epoxidized natural rubber can promote the dispersion and orientation of halloysite nanotubes in styrene-butadiene rubber matrix at nanoscale and strengthen interfacial combination between halloysite nanotubes and styrene-butadiene rubber by the formation of covalent bonds and hydrogen bonds between epoxidized natural rubber and halloysite nanotubes. Consequently epoxidized natural rubber can improve the mechanical properties of the vulcanizates of styrene-butadiene rubber/halloysite nanotubes composites. Besides epoxidized natural rubber can decrease the rolling resistance of the vulcanizates and increase the wet grip property of the vulcanizates.

  18. Rubber linings answer to many problems

    SciTech Connect

    Mehra, L.

    1998-12-31

    The uses of rubber linings in different fields industries are discussed.The physical properties of rubber both natural and synthetic rubber are listed and their importance is evaluated. The aging of rubber is discussed in detail, including effects of temperature on aging of rubber. By virtue of its inherent elasticity and chemical resistance, rubber linings have found many uses in the protection of mining equipment, water treatment tanks and vessels, flue gas desulfurization equipment in power plants and varied process and storage vessels in chemical industries. Rubber has found extensive use in civil engineering field as expansion joints and bladders in dams. Electrical resistance of rubber is useful for its application as an insulating material. Rubber is chemically resistant to acids, alkalies and many salt solutions. Rubber linings are therefore used for protection of steel against these acids, alkalies or salt solutions. The extreme elasticity of rubber has been found useful in its application as a lining material in areas subject to high abrasion. Frequently rubber linings are the linings of choice when a combination of abrasion and chemical attack are to be protected against. Constantly, new formulations of rubber lining compounds are being developed just as new chemical processes are being made. The flexibility of compounding and the relative ease of putting layers of different rubber formulations together in multilayered formulations of rubber lining compounds is leading to new uses of this lining material.

  19. Academic Cloning.

    ERIC Educational Resources Information Center

    Sikula, John P.; Sikula, Andrew F.

    1980-01-01

    The authors define "cloning" as an integral feature of all educational systems, citing teaching practices which reward students for closely reproducing the teacher's thoughts and/or behaviors and administrative systems which tend to promote like-minded subordinates. They insist, however, that "academic cloning" is not a totally…

  20. Academic Cloning.

    ERIC Educational Resources Information Center

    Sikula, John P.; Sikula, Andrew F.

    1980-01-01

    The authors define "cloning" as an integral feature of all educational systems, citing teaching practices which reward students for closely reproducing the teacher's thoughts and/or behaviors and administrative systems which tend to promote like-minded subordinates. They insist, however, that "academic cloning" is not a totally…

  1. Molecular cloning and expression of active Ole e 3, a major allergen from olive-tree pollen and member of a novel family of Ca2+-binding proteins (polcalcins) involved in allergy.

    PubMed

    Ledesma, A; Villalba, M; Batanero, E; Rodríguez, R

    1998-12-01

    A cDNA encoding Ole e 3, a major allergen from olive-tree pollen, has been cloned and sequenced. A strategy based on two-step PCR amplification towards the 5' end and 3' end, with an internal specific primer, has been used. The isolated cDNA contains an open reading frame coding for a polypeptide of 84 amino acids, which is in agreement with the composition and molecular mass of the natural allergen, exhibiting two 12-residue segments homologous to Ca2+-binding sites of EF-hand type. The cDNA was inserted into the pET-11b expression vector and over-expressed in Escherichia coli. The purified recombinant protein shows identical secondary structure to that of the natural allergen and is able to bind both IgE from sera of patients allergic to olive pollen and polyclonal antibodies raised against olive-pollen Ole e 3. The capacity of binding Ca2+ has been demonstrated for both natural and recombinant allergens. RNA transcripts of Ole e 3 were only detected in pollen tissue. Northern-blot and Western-blot analyses of poly(A)+ RNA and protein extracts, respectively, obtained from a variety of olive-tree-related and nonrelated mature pollens demonstrated the presence of Ole e 3 homologous proteins. This indicates a sequence conservation and widespread distribution for this family of Ca2+-binding proteins that can be responsible for allergenic cross-reactivity. We suggest the tentative generic name of polcalcins for the members of this family of Ca2+-binding proteins from pollen.

  2. 'Rubber Duck' on Ceres

    NASA Image and Video Library

    2017-10-12

    This image from NASA's Dawn spacecraft shows a group of craters, left of center, that resembles a rubber duck. Halki Crater, the "head," is 12 miles (20 kilometers) in diameter, while Telepinu Crater, the "body," is 19 miles (31 kilometers) across. They can be found in the global map of Ceres' names. The "beak" crater is unnamed. Halki and Telepinu have both been recently added to the list of official names for Ceres' geological features. They are both named after Hittite (Asia Minor) deities: the goddess of grain and the god of fertility and vegetation, respectively. Dawn acquired this picture on August 20, 2015, from its high-altitude mapping orbit at about 915 miles (1,470 kilometers) above the surface. The center coordinates of this image are 26 degrees north latitude, 339 degrees east longitude. https://photojournal.jpl.nasa.gov/catalog/PIA21909

  3. Rubber stopper remover

    DOEpatents

    Stitt, Robert R.

    1994-01-01

    A device for removing a rubber stopper from a test tube is mountable to an upright wall, has a generally horizontal splash guard, and a lower plate spaced parallel to and below the splash guard. A slot in the lower plate has spaced-apart opposing edges that converge towards each other from the plate outer edge to a narrowed portion, the opposing edges shaped to make engagement between the bottom of the stopper flange and the top edge of the test tube to wedge therebetween and to grasp the stopper in the slot narrowed portion to hold the stopper as the test tube is manipulated downwardly and pulled from the stopper. The opposing edges extend inwardly to adjoin an opening having a diameter significantly larger than that of the stopper flange.

  4. Identification of laticifer-specific genes and their promoter regions from a natural rubber producing plant Hevea brasiliensis.

    PubMed

    Aoki, Yuichi; Takahashi, Seiji; Takayama, Daisuke; Ogata, Yoshiyuki; Sakurai, Nozomu; Suzuki, Hideyuki; Asawatreratanakul, Kasem; Wititsuwannakul, Dhirayos; Wititsuwannakul, Rapepun; Shibata, Daisuke; Koyama, Tanetoshi; Nakayama, Toru

    2014-08-01

    Latex, the milky cytoplasm of highly differentiated cells called laticifers, from Hevea brasiliensis is a key source of commercial natural rubber production. One way to enhance natural rubber production would be to express genes involved in natural rubber biosynthesis by a laticifer-specific overexpression system. As a first step to identify promoters which could regulate the laticifer-specific expression, we identified random clones from a cDNA library of H. brasiliensis latex, resulting in 4325 expressed sequence tags (ESTs) assembled into 1308 unigenes (692 contigs and 617 singletons). Quantitative analyses of the transcription levels of high redundancy clones in the ESTs revealed genes highly and predominantly expressed in laticifers, such as Rubber Elongation Factor (REF), Small Rubber Particle Protein and putative protease inhibitor proteins. HRT1 and HRT2, cis-prenyltransferases involved in rubber biosynthesis, was also expressed predominantly in laticifers, although these transcript levels were 80-fold lower than that of REF. The 5'-upstream regions of these laticifer-specific genes were cloned and analyzed in silico, revealing seven common motifs consisting of eight bases. Furthermore, transcription factors specifically expressed in laticifers were also identified. The common motifs in the laticifer-specific genes and the laticifer-specific transcription factors are potentially involved in the regulation of gene expression in laticifers.

  5. Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis.

    PubMed

    Laibach, Natalie; Hillebrand, Andrea; Twyman, Richard M; Prüfer, Dirk; Schulze Gronover, Christian

    2015-05-01

    Two protein families required for rubber biosynthesis in Taraxacum brevicorniculatum have recently been characterized, namely the cis-prenyltransferases (TbCPTs) and the small rubber particle proteins (TbSRPPs). The latter were shown to be the most abundant proteins on rubber particles, where rubber biosynthesis takes place. Here we identified a protein designated T. brevicorniculatum rubber elongation factor (TbREF) by using mass spectrometry to analyze rubber particle proteins. TbREF is homologous to the TbSRPPs but has a molecular mass that is atypical for the family. The promoter was shown to be active in laticifers, and the protein itself was localized on the rubber particle surface. In TbREF-silenced plants generated by RNA interference, the rubber content was significantly reduced, correlating with lower TbCPT protein levels and less TbCPT activity in the latex. However, the molecular mass of the rubber was not affected by TbREF silencing. The colloidal stability of rubber particles isolated from TbREF-silenced plants was also unchanged. This was not surprising because TbREF depletion did not affect the abundance of TbSRPPs, which are required for rubber particle stability. Our findings suggest that TbREF is an important component of the rubber biosynthesis machinery in T. brevicorniculatum, and may play a role in rubber particle biogenesis and influence rubber production.

  6. Silicone-Rubber Stitching Seal

    NASA Technical Reports Server (NTRS)

    Wang, D. S.

    1985-01-01

    Fabric products protected from raveling by coating threads and filling stitching holes with silicone rubber. Uncored silicone rubber applied to stitching lines with air-pressurized sealant gun. Next, plastic release film placed on coated side, and blanket flipped over so release film lies underneath. Blanket then bagged and adhesive cured under partial vacuum of about 3.5 psi or under pressure. Applications include balloons, parachutes, ultralight aircraft, sails, rescue harnesses, tents, or other fabric products highly stressed in use.

  7. Wear of steel by rubber

    NASA Technical Reports Server (NTRS)

    Gent, A. N.; Pulford, C. T. R.

    1978-01-01

    Wear of a steel blade used as a scraper to abrade rubber surfaces has been found to take place much more rapidly on a cis-polyisoprene (natural rubber) surface than on a cis-polybutadiene surface, and much more rapidly in an inert atmosphere than in air. These observations are attributed to the direct attack upon steel of free-radical species generated by mechanical rupture of elastomer molecules during abrasion.

  8. Wear of steel by rubber

    NASA Technical Reports Server (NTRS)

    Gent, A. N.; Pulford, C. T. R.

    1978-01-01

    Wear of a steel blade used as a scraper to abrade rubber surfaces has been found to take place much more rapidly on a cis-polyisoprene (natural rubber) surface than on a cis-polybutadiene surface, and much more rapidly in an inert atmosphere than in air. These observations are attributed to the direct attack upon steel of free-radical species generated by mechanical rupture of elastomer molecules during abrasion.

  9. Rubber mixing process and its relationship with bound rubber and crosslink density

    NASA Astrophysics Data System (ADS)

    Hasan, A.; Rochmadi; Sulistyo, H.; Honggokusumo, S.

    2017-06-01

    This research studied the relationship between bound rubber and crosslink density based on rubber mixing process. Bound rubber was obtained after natural rubber was masticated and mixed with rubber chemicals and filler while crosslink density was collected after rubber compound was vulcanized. Four methods are used and each method refers to four ways of incorporating carbon black during mixing. The first method, after rubber was masticated for 5 minutes, the addition of rubber chemicals and filler was done simultaneously. Rubber was masticated for 1 minute and continued mixing of rubber chemicals and filler where mixing was different from first method. This was the second method. The third method was the same as the second method but the filler used N 660 while in the second method N 330. The last method is not the same as the first and second, the rubber is only masticated for 3 minutes and then mixed with filler and followed by rubber chemicals sequentially. The results showed that bound rubber and crosslink density were influenced by mixing and mastication process. Bound rubber dropped and crosslink density was relatively stable in the first three mixing methods for increasing carbon black at the beginning of the mixing process. Bound rubber and crosslink density stated opposite results in the fourth mixing method. The higher the bound rubber the lower the crosslink density. Without regard to mixing methods, there is a non-linear relationship between bound rubber formation and crosslink density determination

  10. A polymeric flame retardant additive for rubbers

    SciTech Connect

    Ghosh, S.N.; Maiti, S.

    1993-12-31

    Synthesis of a polyphosphonate by the interfacial polymerization of bisphenol-A (BPA) and dichloro-phenyl phosphine oxide (DCPO) using cetyltrimethyl ammonium chloride (TMAC) as phase transfer catalyst (PTC) was reported. The polyphosphonate was characterized by elemental analysis, IR, TGA, DSC and 1H-NMR spectroscopy. The flame retardancy of the polymer was done by OI study. The polymer was used as a fire retardant additive to rubbers such as natural rubber (NR), styrene-butadiene rubber(SBR), nitrile rubber (NBR) and chloroprene rubber (CR). The efficiency of the fire retardant property of this additive was determined by LOI measurements of the various rubber samples.

  11. Rubber: new allergens and preventive measures.

    PubMed

    Crepy, Marie-Noëlle

    2016-12-01

    Natural rubber latex (NRL) and rubber accelerators are well-known causes of occupational skin diseases. The latest epidemiological data on rubber allergy show that rubber additives are still among the allergens most strongly associated with occupational contact dermatitis, however, a decrease in NRL allergy has been confirmed. A review of recent publications on rubber allergens based on the Pubmed database is presented. New glove manufacturing processes have been developed, such as low-protein natural rubber gloves, vulcanisation accelerator-free gloves, or specific-purpose gloves containing antimicrobial agents or moisturisers. Several websites provide information on allergens found in gloves and/or glove choice according to occupation.

  12. Why Clone?

    MedlinePlus

    ... disease. Find out more about Stem Cells . Reviving Endangered or Extinct Species You might have seen the Jurassic Park movies. ... related goat species to make a male. Cloning endangered species is much easier, mainly because the surviving animals ...

  13. Natural rubber latex allergy.

    PubMed

    Deval, Ravi; Ramesh, V; Prasad, G B K S; Jain, Arun Kumar

    2008-01-01

    Natural rubber latex (NRL) is a ubiquitous allergen as it is a component of > 40,000 products in everyday life. Latex allergy might be attributed to skin contact or inhalation of latex particles. Latex allergy is an IgE-mediated hypersensitivity to NRL, presenting a wide range of clinical symptoms such as angioedema, swelling, cough, asthma, and anaphylactic reactions. Until 1979, latex allergy appeared only as type IV delayed hypersensitivity; subsequently, the proportion of different allergy types drifted towards type IV contact allergy reactions. Several risk factors for sensitization to NRL are already known and well documented. Some authors have established a positive correlation between a history of multiple surgical interventions, atopy, spina bifida malformation, and latex allergy incidence. We suspect an increase in latex allergy incidence in association with increased atopy and sensitivity to environmental allergens in the industrial population. It is often postulated in literature that the groups of workers at risk for this allergy are essentially workers in the latex industry and healthcare professionals. In this population, direct internal and mucosal contact with NRL medical devices may be the route of sensitization as factors such as the number of procedures and use of NRL materials (catheters and tubes) were associated with increased risk of latex sensitization and allergy.

  14. Rolling tires into rubber

    SciTech Connect

    Malloy, M.G.

    1997-06-01

    For Envirotire (Lillington, North Carolina), producing quality crumb rubber this summer is all in a night`s work. The tire recycling facility has operated in Lillington, which is about an hour south of Raleigh, North Carolina, for about a year and a half, since October 1995. In the summer, the plant runs at night to save money in electricity costs by operating during off-peak hours; in the winter, daytime hours also can be off-peak. In contrast to the cryogenic systems used elsewhere to recycle tires, Envirotire`s system works on mechanical principles. Before the tires are even shredded, a worker cuts the white-walls out of the tires manually, so the white does not contaminate the black end-product. A worker places the tires manually on a conveyor, which feed them up to an initial shredder that sections them quickly into pieces. While the tires are on the conveyor, dividing strips on the conveyor mark off a place for each tire. The system takes nine new tires per minute.

  15. Molecular evolution and functional characterisation of haplotypes of an important rubber biosynthesis gene in Hevea brasiliensis.

    PubMed

    Uthup, T K; Rajamani, A; Ravindran, M; Saha, T

    2016-07-01

    Hydroxy-methylglutaryl coenzyme-A synthase (HMGS) is a rate-limiting enzyme in the cytoplasmic isoprenoid biosynthesis pathway leading to natural rubber production in Hevea brasiliensis (rubber). Analysis of the structural variants of this gene is imperative to understand their functional significance in rubber biosynthesis so that they can be properly utilised for ongoing crop improvement programmes in Hevea. We report here allele richness and diversity of the HMGS gene in selected popular rubber clones. Haplotypes consisting of single nucleotide polymorphisms (SNPs) from the coding and non-coding regions with a high degree of heterozygosity were identified. Segregation and linkage disequilibrium analysis confirmed that recombination is the major contributor to the generation of allelic diversity, rather than point mutations. The evolutionarily conserved nature of some SNPs was identified by comparative DNA sequence analysis of HMGS orthologues from diverse taxa, demonstrating the molecular evolution of rubber biosynthesis genes in general. In silico three-dimensional structural studies highlighting the structural positioning of non-synonymous SNPs from different HMGS haplotypes revealed that the ligand-binding site on the enzyme remains impervious to the reported sequence variations. In contrast, gene expression results indicated the possibility of association between specific haplotypes and HMGS expression in Hevea clones, which may have a downstream impact up to the level of rubber production. Moreover, haplotype diversity of the HMGS gene and its putative association with gene expression can be the basis for further genetic association studies in rubber. Furthermore, the data also show the role of SNPs in the evolution of candidate genes coding for functional traits in plants.

  16. 75 FR 57980 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-23

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION... whether revocation of the antidumping duty finding on polychloroprene rubber from Japan would be likely to...

  17. Advances in rubber/halloysite nanotubes nanocomposites.

    PubMed

    Jia, Zhixin; Guo, Baochun; Jia, Demin

    2014-02-01

    The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

  18. Electrospinning of PVC with natural rubber

    NASA Astrophysics Data System (ADS)

    Othman, Muhammad Hariz; Mohamed, Mahathir; Abdullah, Ibrahim

    2013-11-01

    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber's mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  19. Electrospinning of PVC with natural rubber

    SciTech Connect

    Othman, Muhammad Hariz; Abdullah, Ibrahim; Mohamed, Mahathir

    2013-11-27

    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber’s mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  20. Characterizing guayule rubber transferase activity

    SciTech Connect

    Cornish, K.; Backhaus, R.A. )

    1989-04-01

    Rubber transferase (RuT) activity, measured as incorporation of {sup 14}C(isopentenyl pyrophosphate) (IPP) into rubber, was assayed in suspensions of rubber particles purified from bark tissue of Parthenium argentatum, Gray. Rubber particle suspensions (RSP) have high RuT activity which is not diminished by repeated washing of the particles, demonstrating the firm association of the enzyme system with the particles. RuT activity varied with line: 11591 yielded more rubber particles with a greater activity per particle, than did other lines tested. Variation in activity also varied with bark age and season. Activity rapidly declined at temperatures above 16{degree}C in line 593, but was more stable in RSP isolated form line 11591. IPP-incorporation depends upon the concentration of two substrates, IPP and the starter molecule farnesyl pyrophosphate (FPP). In lines 593 and 11591, 20 uM FPP saturated the enzyme present in 6 {times} 10{sup 10} particles {times} cm{sup {minus}3}, whereas about 1 mM IPP was required for saturation. Under saturating FPP, the apparent K{sub m} of RuT was about 250 uM.

  1. Proteome analysis of the large and the small rubber particles of Hevea brasiliensis using 2D-DIGE.

    PubMed

    Xiang, Qiulan; Xia, Kecan; Dai, Longjun; Kang, Guijuan; Li, Yu; Nie, Zhiyi; Duan, Cuifang; Zeng, Rizhong

    2012-11-01

    The rubber particle is a specialized organelle in which natural rubber is synthesised and stored in the laticifers of Hevea brasiliensis (para rubber tree). It has been demonstrated that the small rubber particles (SRPs) has higher rubber biosynthesis ratio than the large rubber particles (LRPs), but the underlying molecular mechanism still remains unknown. In this study, LRPs and SRPs were firstly separated from the fresh latex using differential centrifugation, and two-dimensional difference in-gel electrophoresis (2D-DIGE) combined with MALDI-TOF/TOF was then applied to investigate the proteomic alterations associated with the changed rubber biosynthesis capacity between LRPs and SRPs. A total of 53 spots corresponding to 22 gene products, were significantly altered with the |ratio|≥2.0 and T value ≤0.05, among which 15 proteins were up-regulated and 7 were down-regulated in the SRPs compared with the LRPs. The 15 up-regulated proteins in the SRPs included small rubber particle protein (SRPP), 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS), phospholipase D alpha (PLD α), ethylene response factor 2, eukaryotic translation initiation factor 5A isoform IV (eIF 5A-4), 70-kDa heat shock cognate protein (HSC 70), several unknown proteins, etc., whereas the 7 up-regulated proteins in the LRPs were rubber elongation factor (REF, 19.6kDa), ASR-like protein 1, REF-like stress-related protein 1, a putative phosphoglyceride transfer family protein, β-1,3-glucanase, a putative retroelement, and a hypothetical protein. Since several proteins related to rubber biosynthesis were differentially expressed between LRPs and SRPs, the comparative proteome data may provide useful insights into understanding the mechanism involved in rubber biosynthesis and latex coagulation in H. brasiliensis.

  2. 75 FR 38119 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty finding on polychloroprene rubber from Japan... antidumping duty finding on polychloroprene rubber from Japan would be likely to lead to continuation or...

  3. 63 FR 41284 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    1998-08-03

    ... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on polychloroprene rubber from Japan... antidumping duty order on polychloroprene rubber from Japan would be likely to lead to continuation...

  4. World synthetic rubber consumption is growing

    SciTech Connect

    Not Available

    1987-03-04

    Worldwide consumption of new rubber, both synthetic and natural, has increased. This report includes a prediction of even more growth in the rubber market which was made by the International Institute of Synthetic Rubber Producers (IISRP), based in Houston. Figures are given for worldwide consumption.

  5. Guayule - natural rubber from the desert

    SciTech Connect

    Bucks, D.A.

    1984-11-01

    Guayule is the most likely source of home grown natural rubber in the United States and research is currently underway on methods of increasing rubber content, seed germination and survival, climate and soil requirements and rubber content determination by solvent extraction.

  6. Pressure sensitive conductive rubber blends

    SciTech Connect

    Hassan, H.H. ); Abdel-Bary, E.M. ); El-Mansy, M.K.; Khodair, H.A. )

    1989-12-01

    Butadiene-acrylonitrile rubber (NBR) was blended with polychloroprene (CR) according to standard techniques. The blend was mixed with different concentrations of ZnO. The vulcanized sample was subjected to electrical conductivity ({sigma}) measurements while different values of static pressure were applied on the sample. It was found that samples containing 7.5 phr ZnO showed a reasonable pressure sensitive increase of {sigma}. Furthermore, the {sigma} vs pressure relationship of rubber blend mixed with different concentrations of Fast Extrusion Furnace black (FEF) was investigated. It was found that rubber vulcanizate containing 40 phr FEF resulted in a negative value of the pressure coefficient of conductivity {approx equal} {minus} 4.5 KPa{sup {minus}1}.

  7. Rubber friction and tire dynamics.

    PubMed

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  8. Applicability of Landsat TM data for inventorying and monitoring of rubber (Hevea brasiliensis) plantations in Selangor, Malaysia: Linkages to policies

    NASA Astrophysics Data System (ADS)

    Suratman, Mohd Nazip

    2003-06-01

    Rubber tree (Hevea brasiliensis (Wild ex Adr. De Juss) Muell Arg.) plantations in Malaysia are important sources of natural rubber and wood products. Effective management and appropriate policy for these resources require reliable information on resource dynamics and forecasts of resource availability. The need for inventories and monitoring systems prompted this research into utilising ground information and satellite imagery for developing methods for forest plantation inventory. Monitoring procedures were developed using three dates of Landsat Thematic Mapper (TM) imagery. The specific objectives of the research were: (1) to develop an effective method for inventorying rubber tree plantations using an appropriate combination of satellite imagery and ground sampling in the State of Selangor, Malaysia; (2) to demonstrate the application of a Landsat TM-based rubber volume model in an extended area of rubber plantations south of Kuala Lumpur (KL), Malaysia; (3) to develop an operational methodology for monitoring land use/cover change, with a primary focus on rubber plantations; and (4) to identify relationships between the primary drivers of resource change and policies, and examine the evidence of policies---rubber area change linkages in the study area. Reasonably accurate predictions of the volume, age, and area of rubber plantations were obtained from Landsat TM data. The use of supervised image classification and an image segmentation approach for rubber volume model application showed better performance for volume prediction than a combined land use/cover and rubber volume classification technique, thus providing a useful tool for displaying rubber stand volume within segments or spatial units across the landscape. The combined use of a time series of Landsat TM imagery, modified postclassification change detection, and geographic information system (GIS) techniques made it possible to produce land use/cover change matrices and rubber area change information

  9. Replacing rubber plantations by rain forest in Southwest China--who would gain and how much?

    PubMed

    Ahlheim, Michael; Börger, Tobias; Frör, Oliver

    2015-02-01

    The cultivation of rubber trees in Xishuangbanna Prefecture in China's Yunnan Province has triggered an unprecedented economic development but it is also associated with severe environmental problems. Rubber plantations are encroaching the indigenous rain forests at a large scale and a high speed in Xishuangbanna. Many rare plant and animal species are endangered by this development, the natural water management is disturbed, and even the microclimate in this region has changed over the past years. The present study aims at an assessment of the environmental benefits accruing from a reforestation project partly reversing the deforestation that has taken place over the past years. To this end, a Contingent Valuation survey has been conducted in Xishuangbanna to elicit local residents' willingness to pay for this reforestation program that converts existing rubber plantations back into forest. It is shown that local people's awareness of the environmental problems caused by increasing rubber plantation is quite high and that in spite of the economic advantages of rubber plantation there is a positive willingness among the local population to contribute financially to a reduction of existing rubber plantations for the sake of a partial restoration of the local rain forest. These results could be used for the practical implementation of a Payments for Eco-System Services system for reforestation in Xishuangbanna.

  10. Molecular cloning.

    PubMed

    Lessard, Juliane C

    2013-01-01

    This protocol describes the basic steps involved in conventional plasmid-based cloning. The goals are to insert a DNA fragment of interest into a receiving vector plasmid, transform the plasmid into E. coli, recover the plasmid DNA, and check for correct insertion events.

  11. Improved rubber nanofillers

    SciTech Connect

    Boyle, T. J.

    2012-03-01

    During this task, Silane functionalized TiO2 and HK3Ti4O4(SiO4)3 were sent to Goodyear (GY) for testing. These materials were characterized based on their interaction with the model elastomer, squalene. The Van der Waals interactions and Hamaker Constants for ZnO particles in squalene and rubber materials were characterized and it was determined that a 10-20 nm spacing was necessary between primary filler particles to maintain a stable nanocomposite. Contact angle measurements on the ZnO and ZnO-silane materials indicated that the solvent should wet the particles, and solvophobic attractions should not be present. These studies showed that the surface modification with sulfosilane coupling agents was successful, and high levels of dispersion of the particles remained possible. Further, a novel surface charging phenomenon where negative surface charging is developed in the squalene environment was observed and corroborated by measurements of particle size and of the surface modified materials in squalene. This impacts the dispersion of the particles according to the traditional colloidal interpretation of electrostatic repulsive forces between particles. Additionally, thin nanocomposite fibers were developed using electrospinning. The size and shape of the oxides did not change during the electrospinning process, although the shape of the fiber and the distribution of the particles, particularly for ZnO, was not ideal. There was an obvious increase in elastic modulus and hardness from the addition of the oxides, but differentiating the oxides, and particularly the surfactants, was difficult. The A-1289 lead to the greatest dispersion of the filler particles, while the A-1589 and the NXT produced clustered particle aggregates. This agrees with previous study of these materials in low molecular weight squalene solvent studies reported earlier. The behavior of the nanoparticle ZnO and the microparticle silica is different as well, with the ZnO being contained within

  12. Insights into rubber biosynthesis from transcriptome analysis of Hevea brasiliensis latex.

    PubMed

    Chow, Keng-See; Wan, Kiew-Lian; Isa, Mohd Noor Mat; Bahari, Azlina; Tan, Siang-Hee; Harikrishna, K; Yeang, Hoong-Yeet

    2007-01-01

    Hevea brasiliensis is the most widely cultivated species for commercial production of natural rubber (cis-polyisoprene). In this study, 10,040 expressed sequence tags (ESTs) were generated from the latex of the rubber tree, which represents the cytoplasmic content of a single cell type, in order to analyse the latex transcription profile with emphasis on rubber biosynthesis-related genes. A total of 3,441 unique transcripts (UTs) were obtained after quality editing and assembly of EST sequences. Functional classification of UTs according to the Gene Ontology convention showed that 73.8% were related to genes of unknown function. Among highly expressed ESTs, a significant proportion encoded proteins related to rubber biosynthesis and stress or defence responses. Sequences encoding rubber particle membrane proteins (RPMPs) belonging to three protein families accounted for 12% of the ESTs. Characterization of these ESTs revealed nine RPMP variants (7.9-27 kDa) including the 14 kDa REF (rubber elongation factor) and 22 kDa SRPP (small rubber particle protein). The expression of multiple RPMP isoforms in latex was shown using antibodies against REF and SRPP. Both EST and quantitative reverse transcription-PCR (QRT-PCR) analyses demonstrated REF and SRPP to be the most abundant transcripts in latex. Besides rubber biosynthesis, comparative sequence analysis showed that the RPMPs are highly similar to sequences in the plant kingdom having stress-related functions. Implications of the RPMP function in cis-polyisoprene biosynthesis in the context of transcript abundance and differential gene expression are discussed.

  13. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, E.L.; Bauman, B.D.; Williams, M.A.

    1996-04-09

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.

  14. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, Edwin L.; Scharff, Robert P.; Bauman, Bernard D.; Williams, Mark A.

    1995-01-01

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  15. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, E.L.; Scharff, R.P.; Bauman, B.D.; Williams, M.A.

    1995-01-17

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figures.

  16. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    Bauman, Bernard D.; Williams, Mark A.; Bagheri, Reza

    1997-12-02

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  17. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, Edwin L.; Bauman, Bernard D.; Williams, Mark A.

    1996-04-09

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  18. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    Bauman, B.D.; Williams, M.A.; Bagheri, R.

    1997-12-02

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.

  19. Sprayed Coating Renews Butyl Rubber

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1982-01-01

    Damaged butyl rubber products are renewed by spray technique originally developed for protective suits worn by NASA workers. A commercial two-part adhesive is mixed with Freon-113 (or equivalent) trichlorotrifluoroethane to obtain optimum viscosity for spraying. Mix is applied with an external-air-mix spray gun.

  20. Unraveling the mystery of natural rubber biosynthesis. Part II. Composition and growth of in vitro natural rubber using high-resolution size exclusion chromatography

    SciTech Connect

    Chiang, Cheng Ching K.; Barkakaty, Balaka; Puskas, Judit E.; Xie, Wenshuang; Cornish, Katrina; Peruch, Federic; Deffieux, Alain

    2014-09-01

    The superior properties of natural rubber (cis-1,4-polyisoprene [NR]) are a function of its structure and composition, properties that still remain a mystery and that are irreplaceable by any synthetic rubber. NR from guayule (Parthenium argentatum) has been gaining special interest for its hypoallergenic properties while maintaining superior mechanical properties that are commonly associated with the Brazilian rubber tree (Hevea brasiliensis), the most common source of NR. Techniques exist to isolate washed rubber particles (WRPs) that contain enzymatically active rubber transferase, to study NR biosynthesis, and previous work on the in vitroNRgrowth in Hevea has demonstrated the presence of around 50wt%of a low molecular weight ([MW], Mn <10 000 g/mol) fraction. Structural and compositional analyses of this low MW fraction in Hevea are challenging due to the high protein content. Here, we discuss the analysis and composition of guayule latex and WRPs using high-resolution Size Exclusion Chromatography. We also discuss the composition of the soluble fraction of inactive guayule latex using matrix-assisted laser desorption ionization/time of flight mass spectrometry.

  1. Rubber lining for FGD scrubbers for waste incinerator plants

    SciTech Connect

    Rullmann, H.E.

    1999-11-01

    Flue gas desulfurization scrubbers for waste incineration plants can be lined with soft rubber or hard rubber for corrosion protection. Hard rubber is cured under high temperature and pressure in an autoclave. The advantage of hard rubber is the excellent temperature and chemical resistance. The authors have experience with hard rubber lined scrubbers that are in service without failures for over 20 years.

  2. The enzymatic synthesis of rubber polymer

    SciTech Connect

    Venkatachalam, K.V.; Wooten, L.; Benedict, C.R. )

    1990-05-01

    Washed rubber particles (WRP) isolated from stem homogenates of Parthenium argentatum by ultracentrifugation and gel filtration on columns of LKB Ultrogel AcA34 contain a tightly bound rubber transferase which catalyzes the polymerization of IPP into rubber polymer. The polymerization reaction requires Mg{sup 2+}, IPP and an allylic-PP. The Km values for Mg{sup 2+}, IPP and DMAPP are 5.2{times}10{sup {minus}4}M, 8.3{times}10{sup {minus}5} M and 9.6{times}10{sup {minus}5}M respectively. Gel permeation chromatography of the enzymatic polymer product on 3 linear columns of 1{times}10{sup 6} to 500 {angstrom} Ultrastyragel shows that the in vitro formed polymer has a similar mol wt to natural rubber. Over 90% of the in vitro formation of the rubber polymer was a de novo polymerization reaction from DMAPP initiator and IPP monomers. The bound rubber polymerase substantially differs from cytosolic rubber transferase which catalyzes only chain lengthening reactions. Treatment of the WRP with Chaps solubilized the bound rubber transferase which was further purified by DEAE-cellulose chromatography. The purified preparation primarily consists of a 52 kD polypeptide which binds to a photolabile substrate analog. The soluble rubber transferase catalyzes the synthesis of a 1{times}10{sup 5} mol wt rubber polymer from Mg{sup 2+}, DMAPP, IPP and detergent.

  3. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-09-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  4. Prehistoric polymers: rubber processing in ancient mesoamerica

    PubMed

    Hosler; Burkett; Tarkanian

    1999-06-18

    Ancient Mesoamerican peoples harvested latex from Castilla elastica, processed it using liquid extracted from Ipomoea alba (a species of morning glory vine), and fashioned rubber balls, hollow rubber figurines, and other rubber artifacts from the resulting material. Chemical and mechanical analyses of the latex and of the processed rubber indicate that the enhanced elastic behavior of the rubber relative to the unprocessed latex is due to purification of the polymer component and to an increase in the strength and number of interchain interactions that are induced by organic compounds present in I. alba. These ancient peoples' control over the properties of latex and processed rubber gave rise to the Mesoamerican ball game, a central ritual element in all ancient Mesoamerican societies.

  5. Compatibilizer for crumb rubber modified asphalt

    SciTech Connect

    Labib, M.E.; Memon, G.M.; Chollar, B.H.

    1996-12-31

    The United States of America discards more than 300 million tires each year, and out of that a large fraction of the tires is dumped into stock piles. This large quantity of tires creates an environmental problem. The use of scrap tires is limited. There is a usage potential in such fields as fuel for combustion and Crumb Rubber-Modified Asphalt binder (CRMA). The use of crumb rubber in modifying asphalt is not a new technique; it is been used since early 1960 by pavement engineers. Crumb rubber is a composite of different blends of natural and synthetic rubber (natural rubber, processing oils, polybutadiene, polystyrene butadiene, and filler). Prior research had concluded that the performance of crumb rubber modified asphalt is asphalt dependent. In some cases it improves the Theological properties and in some cases it degrades the properties of modified asphalt.

  6. Adding crumb rubber into exterior wall materials.

    PubMed

    Zhu, Han; Thong-On, Norasit; Zhang, Xiong

    2002-10-01

    In Arizona US, most houses are built with walls covered by stuccos/coatings/mortars. This paper presents an explorative investigation of adding crumb rubber into stuccos/coatings/mortars. A series of experiments are conducted to examine the thermal and mechanical performance of the crumb rubber mixes. The results show that, the mixes with crumb rubber do exhibit more desirable performances like being high in crack-resistance and thermal insulation, and low in thermal expansion/contraction. The drawback for the crumb rubber mixes is the reduction in compressive strength, but which can be compensated by other means. As a site experiment, an area of 100 square-feet of crumb rubber coatings for two mix designs is sprayed on a tire-adobe wall. After being sprayed more than 14 months, the coatings apparently are in good condition. Significance of this study is that this practice, if accepted, will yield improved products that consume large quantities of crumb rubber.

  7. 'Silicone rubber' lenses in aphakia.

    PubMed

    Ruben, M; Guillon, M

    1979-07-01

    Tesicon, one of the commercially available 'silicone rubber' lenses, was used in the correction of aphakic patients. In 74% of cases the lenses were considered successful for a daily wear regimen by the patient. Furthermore, a small number of patients could wear this lens without interruption for 3 to 6 days at a time. Despite this good acceptance by patients, corneal problems (mainly staining) and lens problems (dry surfaces) were frequently encountered.

  8. Blow molding of melt processible rubber

    SciTech Connect

    Abell, W.R.; Stuart, R.E.; Myrick, R.E.

    1991-07-01

    This article discusses the advantages of making hollow rubber parts by blow molding thermoplastic elastomers (TPEs) versus conventional rubber processing. It describes the various types of blow molding processes and it provides some insight into the rheological properties of melt processible rubber (MPR) and how MPR should be molded by each of these processes. A number of blow molded applications for MPR are also discussed.

  9. Chemistry of rubber processing and disposal.

    PubMed

    Bebb, R L

    1976-10-01

    The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis.

  10. Rubber friction: comparison of theory with experiment.

    PubMed

    Lorenz, B; Persson, B N J; Dieluweit, S; Tada, T

    2011-12-01

    We have measured the friction force acting on a rubber block slid on a concrete surface. We used both unfilled and filled (with carbon black) styrene butadiene (SB) rubber and have varied the temperature from -10 °C to 100 °C and the sliding velocity from 1 μm/s to 1000 μm/s. We find that the experimental data at different temperatures can be shifted into a smooth master-curve, using the temperature-frequency shifting factors obtained from measurements of the bulk viscoelastic modulus. The experimental data has been analyzed using a theory which takes into account the contributions to the friction from both the substrate asperity-induced viscoelastic deformations of the rubber, and from shearing the area of real contact. For filled SB rubber the frictional shear stress σ(f) in the area of real contact results mainly from the energy dissipation at the opening crack on the exit side of the rubber-asperity contact regions. For unfilled rubber we instead attribute σ(f) to shearing of a thin rubber smear film, which is deposited on the concrete surface during run in. We observe very different rubber wear processes for filled and unfilled SB rubber, which is consistent with the different frictional processes. Thus, the wear of filled SB rubber results in micrometer-sized rubber particles which accumulate as dry dust, which is easily removed by blowing air on the concrete surface. This wear process seams to occur at a steady rate. For unfilled rubber a smear film forms on the concrete surface, which cannot be removed even using a high-pressure air stream. In this case the wear rate appears to slow down after some run in time period.

  11. Optimization of aqueous degassing of rubber solutions

    SciTech Connect

    Rotenberg, E.B.; Slutsman, N.N.

    1983-02-01

    The optimality criterion of the aqueous degassing process of rubber solutions is proposed. The limitation system for the variables of the process is formulated. The problems of determination of the optimal temperature and average residence time of a rubber crumb in each degasifier, the number of degasifiers, and the total average residence time of a rubber crumb in the system at the planning and control stages are solved.

  12. Recycling rubber wastes. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-02-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains a minimum of 96 citations and includes a subject term index and title list.)

  13. Recycling rubber wastes. (Latest citations from the rubber and plastics research association database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains a minimum of 89 citations and includes a subject term index and title list.)

  14. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, R.A.; Snowden-Swan, L.J.

    1997-01-28

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber. 8 figs.

  15. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, Robert A.; Snowden-Swan, Lesley J.

    1997-01-01

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber.

  16. The functional analyses of the cis-prenyltransferase and the rubber elongation factor in rubber biosynthesis

    USDA-ARS?s Scientific Manuscript database

    Natural rubber (cis-1,4-polyisoprene) is an essential plant derived commodity required for the manufacture of numerous industrial, medical and household items. Rubber is synthesized and sequestered on cytsolic vesicles known as rubber particles. When provided with farnesyl pyrophosphate (FPP) and is...

  17. Chemical modifications of liquid natural rubber

    NASA Astrophysics Data System (ADS)

    Azhar, Nur Hanis Adila; Rasid, Hamizah Md; Yusoff, Siti Fairus M.

    2016-11-01

    Liquid natural rubber (LNR) was synthesized via photosentisized degradation of natural rubber (NR). LNR was modified into epoxidized liquid natural rubber (LENR) and hydroxylated liquid natural rubber (LNR-OH) using Na2WO4/CH3COOH/H2O2 catalytic system. Chemical structures of LNR and modified LNRs were characterized using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and 1H Nuclear Magnetic Resonance (NMR) spectroscopies. Integration of 1H NMR was used to calculate the epoxy content (%) of LENR. 1H NMR detected the formation of LNR-OH after prolonged heating and increased of catalyst in oxidation reaction.

  18. Malaria-associated rubber plantations in Thailand.

    PubMed

    Bhumiratana, Adisak; Sorosjinda-Nunthawarasilp, Prapa; Kaewwaen, Wuthichai; Maneekan, Pannamas; Pimnon, Suntorn

    2013-01-01

    Rubber forestry is intentionally used as a land management strategy. The propagation of rubber plantations in tropic and subtropic regions appears to influence the economical, sociological and ecological aspects of sustainable development as well as human well-being and health. Thailand and other Southeast Asian countries are the world's largest producers of natural rubber products; interestingly, agricultural workers on rubber plantations are at risk for malaria and other vector-borne diseases. The idea of malaria-associated rubber plantations (MRPs) encompasses the complex epidemiological settings that result from interactions among human movements and activities, land cover/land use changes, agri-environmental and climatic conditions and vector population dynamics. This paper discusses apparent issues pertaining to the connections between rubber plantations and the populations at high risk for malaria. The following questions are addressed: (i) What are the current and future consequences of rubber plantations in Thailand and Southeast Asia relative to malaria epidemics or outbreaks of other vector-borne diseases? (ii) To what extent is malaria transmission in Thailand related to the forest versus rubber plantations? and (iii) What are the vulnerabilities of rubber agricultural workers to malaria, and how contagious is malaria in these areas?

  19. Rubber Elasticity in Highly Crosslinked Polyesters.

    DTIC Science & Technology

    Esters, *Polymers, *Elastic properties, Rubber, Propylene glycol , Maleic acid, Anhydrides, Phthalic acids, Mechanical properties, Molecular structure, Crosslinking(Chemistry), Polymerization, Styrenes, Temperature, Transition temperature, Molecular weight

  20. Inter- and intra-annual variations of transpiration at a rubber stand in lowland of central Cambodia

    NASA Astrophysics Data System (ADS)

    Kobayashi, Nakako; Kumagai, Tomo'omi; Miyazawa, Yoshiyuki; Matsumoto, Kazuho; Tateishi, Makiko; Tiva, Lim Khan; Mudd, Ryan; Giambelluca, Thomas; Song, Yin

    2013-04-01

    In Southeast Asia, rubber plantation is rapidly expanding, and thus understanding the level of water consumption and tree physiology is a matter of importance to know the impacts on the local hydrology. Intra- and inter-annual variations in transpiration rate (Et) at a rubber stand, growing in lowland of central Cambodia, were examined during two years based on sap flow measurements. As for seasonality, Et was generally large in the rainy season and small in the dry season, showing sharp short-time drop in synchronization with the shedding in late January. Daily stand Et was ~ 2.0 mm day-1 in 2010 and ~ 2.4 mm day-1 in 2011 at the maximum. An analysis of non-linear multiple regression for the canopy conductance (gc) in the two years showed that the stomatal response of rubber trees was well explained by the changes in solar radiation, vapour pressure deficit, soil moisture availability, leaf area, and tree diameter. Sensitivity of gc to the atmospheric drought indicates isohydric behavior of rubber trees, while the same analysis for each year showed possibility of change in leaf characteristics due to tree maturity and/or initiation of latex tapping. The best fit model also predicted relatively small sensitivity of gc to the soil moisture deficit and rapid decrease in gc under extreme drought conditions. Annual stand Et estimated with the gc obtained in the present analysis was 469 mm yr-1 in 2010, while it increased up to 658 mm yr-1 in 2011. To find out the most important environmental variables, we examined the effect of each variable by keeping the others unchanged. This hypothesis analysis showed that in the young rubber stand which were growing very rapidly, inter-annual change of stand Et was determined mainly by the tree growth rate, not by the change of surrounding environments in the air and the soil.

  1. [Eugenics and human cloning].

    PubMed

    Boloz, W

    2001-01-01

    Because of legislative bans there are still no reports of human cloning. However eager public debate is currently running, concerning medical, legal, social and ethical aspects of human cloning. Arguments for and against human cloning are presented. An important argument against cloning is the danger of eugenic tendencies connected with cloning, which could lead to genetic discrimination.

  2. In vitro synthesis of high molecular weight rubber by Hevea small rubber particles.

    PubMed

    Rojruthai, Porntip; Sakdapipanich, Jitladda Tangpakdee; Takahashi, Seiji; Hyegin, Lee; Noike, Motoyoshi; Koyama, Tanetoshi; Tanaka, Yasuyuki

    2010-02-01

    Hevea brasiliensis is one of few higher plants producing the commercial natural rubber used in many significant applications. The biosynthesis of high molecular weight rubber molecules by the higher plants has not been clarified yet. Here, the in vitro rubber biosynthesis was performed by using enzymatically active small rubber particles (SRP) from Hevea. The mechanism of the in vitro rubber synthesis was investigated by the molecular weight distribution (MWD). The highly purified SRP prepared by gel filtration and centrifugation in the presence of Triton((R)) X-100 showed the low isopentenyl diphosphate (IPP) incorporation for the chain extension mechanism of pre-existing rubber. The MWD of in vitro rubber elongated from the pre-existing rubber chains in SRP was analyzed for the first time in the case of H. brasiliensis by incubating without the addition of any initiator. The rubber transferase activity of 70% incorporation of the added IPP (w/w) was obtained when farnesyl diphosphate was present as the allylic diphosphate initiator. The in vitro synthesized rubber showed a typical bimodal MWD of high and low molecular weight fractions in GPC analysis, which was similar to that of the in vivo rubber with peaks at around 10(6) and 10(5) Da or lower. The reaction time independence and dependence of molecular weight of high and low molecular weight fractions, respectively, indicated that the high molecular weight rubber was synthesized from the chain extension of pre-existing rubber molecules whereas the lower one was from the chain elongation of rubber molecules newly synthesized from the added allylic substrates.

  3. Roughness Perception during the Rubber Hand Illusion

    ERIC Educational Resources Information Center

    Schutz-Bosbach, Simone; Tausche, Peggy; Weiss, Carmen

    2009-01-01

    Watching a rubber hand being stroked by a paintbrush while feeling identical stroking of one's own occluded hand can create a compelling illusion that the seen hand becomes part of one's own body. It has been suggested that this so-called rubber hand illusion (RHI) does not simply reflect a bottom-up multisensory integration process but that the…

  4. Cotton-Fiber-Filled Rubber Insulation

    NASA Technical Reports Server (NTRS)

    Anderson, Floyd A.

    1987-01-01

    Carbonization of fibers at high temperatures improves strength and erosion resistance. Cotton linters tested as replacement for asbestos filler currently used in rubber insulation in solid rocket motors. Cotton-filled rubber insulation has industrial uses; in some kinds of chemical- or metal-processing equipment, hoses, and protective clothing.

  5. 69 FR 78474 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2004-12-30

    ... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION... Japan. SUMMARY: The Commission hereby gives notice of the scheduling of a full review pursuant to... revocation of the antidumping duty order on polychloroprene rubber from Japan would be likely to lead...

  6. RADIATION INDUCED VULCANIZATION OF RUBBER LATEX

    DOEpatents

    Mesrobian, R.B.; Ballantine, D.S.; Metz, D.J.

    1964-04-28

    A method of vulcanizing rubber latex by exposing a mixture containing rubber latex and from about 15 to about 21.3 wt% of 2,5-dichlorostyrene to about 1.1 megarads of gamma radiation while maintaining the temperature of the mixture at a temperature ranging between from about 56 to about 59 deg C is described. (AEC)

  7. Zinc leaching from tire crumb rubber.

    PubMed

    Rhodes, Emily P; Ren, Zhiyong; Mays, David C

    2012-12-04

    Because tires contain approximately 1-2% zinc by weight, zinc leaching is an environmental concern associated with civil engineering applications of tire crumb rubber. An assessment of zinc leaching data from 14 studies in the published literature indicates that increasing zinc leaching is associated with lower pH and longer leaching times, but the data display a wide range of zinc concentrations, and do not address the effect of crumb rubber size or the dynamics of zinc leaching during flow through porous crumb rubber. The present study was undertaken to investigate the effect of crumb rubber size using the synthetic precipitation leaching procedure (SPLP), the effect of exposure time using quiescent batch leaching tests, and the dynamics of zinc leaching using column tests. Results indicate that zinc leaching from tire crumb rubber increases with smaller crumb rubber and longer exposure time. Results from SPLP and quiescent batch leaching tests are interpreted with a single-parameter leaching model that predicts a constant rate of zinc leaching up to 96 h. Breakthrough curves from column tests displayed an initial pulse of elevated zinc concentration (~3 mg/L) before settling down to a steady-state value (~0.2 mg/L), and were modeled with the software package HYDRUS-1D. Washing crumb rubber reduces this initial pulse but does not change the steady-state value. No leaching experiment significantly reduced the reservoir of zinc in the crumb rubber.

  8. Amino acid modifiers in guayule rubber compounds

    USDA-ARS?s Scientific Manuscript database

    Tire producers are increasingly interested in biobased materials, including rubber but also as compounding chemicals. An alternative natural rubber for tire use is produced by guayule, a woody desert shrub native to North America. Alternative compounding chemicals include naturally-occurring amino a...

  9. Guayule: Culture, breeding and rubber production

    USDA-ARS?s Scientific Manuscript database

    Pressure on worldwide Hevea rubber supplies and other factors are renewing interest in guayule rubber. The objective of this chapter is to review recent and past research dealing with guayule production, breeding, and product development. Production research continues to show that although guayule i...

  10. Cotton-Fiber-Filled Rubber Insulation

    NASA Technical Reports Server (NTRS)

    Anderson, Floyd A.

    1987-01-01

    Carbonization of fibers at high temperatures improves strength and erosion resistance. Cotton linters tested as replacement for asbestos filler currently used in rubber insulation in solid rocket motors. Cotton-filled rubber insulation has industrial uses; in some kinds of chemical- or metal-processing equipment, hoses, and protective clothing.

  11. Rubber transferase in guayule plants. [Parthenium argentatum

    SciTech Connect

    Rosenfield, C.L.; Foster, M.A.; Benedict, C.R.

    1986-04-01

    Rubber transferase catalyzes the transfer of cis-1,4-polyprenyl-PP to isopentenyl-PP (IPP) with the elimination of PP/sub i/. Rubber transferase activity in guayule (Parthenium argentatum Gray) stems was localized in the lipid fraction of the homogenate following centrifugation in buffer and 0.4M Mannitol. Washed rubber particles were obtained by the chromatography of the lipid fraction on Ultrogel columns with an exclusion limit of 750,000 daltons by the procedure of B.G. Audley (private communication). The rubber particles catalyzed the incorporation of /sup 14/C-IPP into cis-polyisoprene. The radioactive cis-polyisoprene was identified by ozonolysis and chromatography of the resulting /sup 14/C-levulinic acid. The synthesis of cis-polyisoprene in the rubber particles required Mg/sup 2 +/ and IPP and was stimulated 2-fold with the addition of DMAPP. Rubber synthesis in guayule plants growing in the Permian Basin of West Texas does not occur during summer months but is induced by the cold night temperatures of the fall and winter. From August to December individual plants (which were transplanted in May) accumulated from 66mg to 11,800mg or rubber. During this period there was a 4-fold increase in rubber transferase activity in stem homogenates induced by the low temperatures.

  12. Roughness Perception during the Rubber Hand Illusion

    ERIC Educational Resources Information Center

    Schutz-Bosbach, Simone; Tausche, Peggy; Weiss, Carmen

    2009-01-01

    Watching a rubber hand being stroked by a paintbrush while feeling identical stroking of one's own occluded hand can create a compelling illusion that the seen hand becomes part of one's own body. It has been suggested that this so-called rubber hand illusion (RHI) does not simply reflect a bottom-up multisensory integration process but that the…

  13. Clone history shapes Populus drought responses.

    PubMed

    Raj, Sherosha; Bräutigam, Katharina; Hamanishi, Erin T; Wilkins, Olivia; Thomas, Barb R; Schroeder, William; Mansfield, Shawn D; Plant, Aine L; Campbell, Malcolm M

    2011-07-26

    Just as animal monozygotic twins can experience different environmental conditions by being reared apart, individual genetically identical trees of the genus Populus can also be exposed to contrasting environmental conditions by being grown in different locations. As such, clonally propagated Populus trees provide an opportunity to interrogate the impact of individual environmental history on current response to environmental stimuli. To test the hypothesis that current responses to an environmental stimulus, drought, are contingent on environmental history, the transcriptome- level drought responses of three economically important hybrid genotypes-DN34 (Populus deltoides × Populus nigra), Walker [P. deltoides var. occidentalis × (Populus laurifolia × P. nigra)], and Okanese [Walker × (P. laurifolia × P. nigra)]-derived from two different locations were compared. Strikingly, differences in transcript abundance patterns in response to drought were based on differences in geographic origin of clones for two of the three genotypes. This observation was most pronounced for the genotypes with the longest time since establishment and last common propagation. Differences in genome-wide DNA methylation paralleled the transcriptome level trends, whereby the clones with the most divergent transcriptomes and clone history had the most marked differences in the extent of total DNA methylation, suggesting an epigenomic basis for the clone history-dependent transcriptome divergence. The data provide insights into the interplay between genotype and environment in the ecologically and economically important Populus genus, with implications for the industrial application of Populus trees and the evolution and persistence of these important tree species and their associated hybrids.

  14. Rubber elasticity: From topology to filled elastomers

    SciTech Connect

    Heinrich, G.; Vilgis, T.A.

    1993-12-31

    Various new aspects in the elasticity of rubbers and statistics of unfilled and filled elastomers, together with various consequences for practical application are discussed. It is shown that the role of network topology is crucial in the statistics of rubbers. This is seen mostly on the influence of heterogeneities of crosslink density which determine the elastic modulus, ultimate properties as well as the dynamical behavior. The filler effects, entanglements in filled rubbers, and the filler/bound rubber/mobile rubber problem are discussed from a novel point of view. A localization model is adopted, where it can be shown that on a rough (filler) surface more polymer can be adsorbed compared to a flat surface with similar energetic properties. The role of carbon black networking and fractal properties of the filler are discussed in relation to the dynamic-mechanical properties of the elastomer.

  15. Temperature field in rubber vibration isolators

    NASA Astrophysics Data System (ADS)

    Abdulhadi, M. Issa

    1985-02-01

    The temperature field inside a vibrating rubber solid cylinder is investigated. The rubber cylinder, a specimen of a vibration isolator rubber (Neoprene GR), is subjected to a repeatedly cyclic compressive force by means of an electrodynamic shaker. In the experimental investigation the temperatures at 16 different locations inside the cylinder have been measured by means of copper-constantan thermocouples. After the estimation of the heat generated per unit volume per unit time with the help of the estimated damping and stiffness coefficients of rubber, one can attempt the solution of the heat conduction equation describing the temperature field inside the rubber specimen. The values of the temperature found from the analytical investigation compare fairly well with the experimental measurements.

  16. Thermal Fluctuations and Rubber Elasticity

    NASA Astrophysics Data System (ADS)

    Xing, Xiangjun; Goldbart, Paul M.; Radzihovsky, Leo

    2007-02-01

    The effects of thermal elastic fluctuations in rubbery materials are examined. It is shown that, due to their interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation and shows good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation.

  17. Thermal fluctuations and rubber elasticity.

    PubMed

    Xing, Xiangjun; Goldbart, Paul M; Radzihovsky, Leo

    2007-02-16

    The effects of thermal elastic fluctuations in rubbery materials are examined. It is shown that, due to their interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation and shows good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation.

  18. Rubber rolling over a sphere

    NASA Astrophysics Data System (ADS)

    Koiller, J.; Ehlers, K.

    2007-04-01

    “Rubber” coated bodies rolling over a surface satisfy a no-twist condition in addition to the no slip condition satisfied by “marble” coated bodies [1]. Rubber rolling has an interesting differential geometric appeal because the geodesic curvatures of the curves on the surfaces at corresponding points are equal. The associated distribution in the 5 dimensional configuration space has 2 3 5 growth (these distributions were first studied by Cartan; he showed that the maximal symmetries occurs for rubber rolling of spheres with 3:1 diameters ratio and materialize the exceptional group G 2). The 2 3 5 nonholonomic geometries are classified in a companion paper [2] via Cartan’s equivalence method [3]. Rubber rolling of a convex body over a sphere defines a generalized Chaplygin system [4 8] with SO(3) symmetry group, total space Q = SO(3) × S 2 and base S 2, that can be reduced to an almost Hamiltonian system in T* S 2 with a non-closed 2-form ωNH. In this paper we present some basic results on the sphere-sphere problem: a dynamically asymmetric but balanced sphere of radius b (unequal moments of inertia I j but with center of gravity at the geometric center), rubber rolling over another sphere of radius a. In this example ωNH is conformally symplectic [9]: the reduced system becomes Hamiltonian after a coordinate dependent change of time. In particular there is an invariant measure, whose density is the determinant of the reduced Legendre transform, to the power p = 1/2( b/a - 1). Using sphero-conical coordinates we verify the result by Borisov and Mamaev [10] that the system is integrable for p = -1/2 (ball over a plane). They have found another integrable case [11] corresponding to p = -3/2 (rolling ball with twice the radius of a fixed internal ball). Strikingly, a different set of sphero-conical coordinates separates the Hamiltonian in this case. No other integrable cases with different I j are known.

  19. A protein extraction method for low protein concentration solutions compatible with the proteomic analysis of rubber particles.

    PubMed

    Wang, Dan; Sun, Yong; Tong, Zheng; Yang, Qian; Chang, Lili; Meng, Xueru; Wang, Limin; Tian, Weimin; Wang, Xuchu

    2016-11-01

    The extraction of high-purity proteins from the washing solution (WS) of rubber particles (also termed latex-producing organelles) from laticifer cells in rubber tree for proteomic analysis is challenging due to the low concentration of proteins in the WS. Recent studies have revealed that proteins in the WS might play crucial roles in natural rubber biosynthesis. To further examine the involvement of these proteins in natural rubber biosynthesis, we designed an efficiency method to extract high-purity WS proteins. We improved our current borax and phenol-based method by adding reextraction steps with phenol (REP) to improve the yield from low protein concentration samples. With this new method, we extracted WS proteins that were suitable for proteomics. Indeed, compared to the original borax and phenol-based method, the REP method improved both the quality and quantity of isolated proteins. By repeatedly extracting from low protein concentration solutions using the same small amount of phenol, the REP method yielded enough protein of sufficiently high-quality from starting samples containing less than 0.02 mg of proteins per milliliter. This method was successfully applied to extract the rubber particle proteins from the WS of natural rubber latex samples. The REP-extracted WS proteins were resolved by 2DE, and 28 proteins were positively identified by MS. This method has the potential to become widely used for the extraction of proteins from low protein concentration solutions for proteomic analysis.

  20. Mapping tropical forests and rubber plantations on Hainan Island using PALSAR and multi-temporal Landsat data

    NASA Astrophysics Data System (ADS)

    Dong, J.; Chen, B.; Xiao, X.; Li, X.; Kou, W.; Wu, Z.

    2015-12-01

    Updated and accurate maps for tropical forests and plantations such as natural rubber (Hevea brasiliensis) are of vital importance for ecological study and optimal forest management practices. However, the existing optical-based efforts are limited by the coverage of clouds and shadows, which is prevent in the tropical regions. In this study, we combined PALSAR 25-m mosaic and 30-m multi-temporal Landsat (TM/ETM+) images to map tropical forests and rubber plantation in Hainan Island, China. Based on PALSAR imagery and maximum NDVI, we first identified tropical forests in 2010 using a decision tree algorithm. The resultant forest map has high accuracy (producer/user accuracy > 96%) and can serve as a reliable base map for rubber plantation mapping. Deciduous rubber plantation subsequently extracted from the PALSAR/Landsat-based forest map according to its high NDVI in peak growing season, and low LSWI during the rapid defoliation and foliation stage. The rubber map had good accuracy when validated by ground truth-based Region of Interests (ROIs) and three farm-scale land use maps. This study has clearly demonstrated the advantage of integrating PALSAR and Landsat images and phenology-based algorithm to map tropical forests and rubber plantation.

  1. Extraction and characterization of latex and natural rubber from rubber-bearing plants.

    PubMed

    Buranov, Anvar U; Elmuradov, Burkhon J

    2010-01-27

    Consecutive extraction of latex and natural rubber from the roots of rubber-bearing plants such as Taraxacum kok-saghyz (TKS), Scorzonera tau-saghyz (STS), and Scorzonera Uzbekistanica (SU) were carried out. Latex extraction was carried via two methods: Blender method and Flow method. The results of latex extraction were compared. Cultivated rubber-bearing plants contained slightly higher latex contents compared to those from wild fields. Several creaming agents for latex extraction were compared. About 50% of total natural rubber was extracted as latex. The results of the comparative studies indicated that optimum latex extraction can be achieved with Flow method. The purity of latex extracted by Blender method ( approximately 75%) was significantly lower than that extracted by Flow method (99.5%). When the latex particles were stabilized with casein, the latex was concentrated significantly. Through concentrating latex by flotation, the latex concentration of 35% was obtained. Bagasse contained mostly solid natural rubber. The remaining natural rubber in the bagasse (left after the latex extraction) was extracted using sequential solvent extraction first with acetone and then with several nonpolar solvents. Solid natural rubber was analyzed for gel content and characterized by size exclusion chromatography (SEC) for molecular weight determinations. SEC of solid natural rubber has shown that the molecular weight is about 1.8E6 and they contain less gel compared to TSR20 (Grade 20 Technically Specified Rubber), a commercial natural rubber from Hevea brasiliensis.

  2. Removal intensity and tree size effects on harvesting cost and profitability

    Treesearch

    R. Kluender; D. Lortz; W. McCoy; B. Stokes; J. Klepac

    1997-01-01

    Sixteen stands were harvested at intensities (proportion of basal area removed) ranging from 0.27 to 1.00. Logging contractors used chain saws and rubber-tired skidders. Harvested sites were similar in slope and tree size. Harvest cost per hundred cubic feet of wood (CCF) was inversely related to harvest intensity and tree size. Harvesting profitability per CCF was...

  3. A tree classification for the selection forests of the Sierra Nevada

    Treesearch

    Duncan Dunning

    1928-01-01

    Individuality in man is accepted without question. In domestic animals, also, good and bad individuals are generally recognized. Even in some cultivated plants —orange trees and rubber trees— the poor producers are searched out and eliminated. Indeed, individual variability is a normal condition in all groups of organisms. Yet forest trees are...

  4. Following the fate of harvest-damaged trees 13 years after harvests

    Treesearch

    Randy G. Jensen; John M. Kabrick

    2014-01-01

    Logging damage to residual trees during harvest operations can reduce the future volume, quality, and value of wood products. Timber harvests in 1996 on the Missouri Ozark Forest Ecosystem Project (MOFEP) provided a rare opportunity to follow the fate of trees wounded by felling or by skidding with rubber-tired skidders.

  5. Exposure to rubber fume and rubber process dust in the general rubber goods, tyre manufacturing and retread industries.

    PubMed

    Dost, A A; Redman, D; Cox, G

    2000-08-01

    This study assesses the current patterns and levels of exposure to rubber fume and rubber process dust in the British rubber industry and compares and contrasts the data obtained from the general rubber goods (GRG), retread tire (RT) and new tire (NT) sectors. A total of 179 rubber companies were visited and data were obtained from 52 general rubber goods, 29 retread tire and 7 new tire manufacturers. The survey was conducted using a questionnaire and included a walk-through inspection of the workplace to assess the extent of use of control measures and the nature of work practices being employed. The most recent (predominantly 1995-97) exposure monitoring data for rubber fume and rubber process dust were obtained from these companies; no additional sampling was conducted for the purpose of this study. In addition to the assessment of exposure data, evaluation of occupational hygiene reports for the quality of information and advice was also carried out.A comparison of the median exposures for processes showed that the order of exposure to rubber fume (E, in mg m(-3)) is: E(moulding) (0.40) approximately E(extrusion) (0.33)>E(milling) (0.18) for GRG; E(press) (0. 32)>E(extrusion) (0.19)>E(autoclave) (0.10) for RT; and E(press) (0. 22) approximately E(all other) (0.22) for NT. The order of exposure to rubber fume between sectors was E(GRG) (0.40)>E(RT) (0.32)>E(NT) (0.22). Median exposures to rubber process dust in the GRG was E(weighing) (4.2)>E(mixing) (1.2) approximately E(milling) (0.8) approximately E(extrusion) (0.8) and no significant difference (P=0. 31) between GRG and NT sectors. The findings compare well with the study carried out in the Netherlands [Kromhout et al. (1994), Annals of Occupational Hygiene 38(1), 3-22], and it is suggested that the factors governing the significant differences noted between the three sectors relate principally to the production and task functions and also to the extent of controls employed. Evaluation of occupational

  6. On classical cloning and no-cloning

    NASA Astrophysics Data System (ADS)

    Teh, Nicholas J.

    2012-02-01

    It is part of information theory folklore that, while quantum theory prohibits the generic (or universal) cloning of states, such cloning is allowed by classical information theory. Indeed, many take the phenomenon of no-cloning to be one of the features that distinguishes quantum mechanics from classical mechanics. In this paper, we argue that pace conventional wisdom, in the case where one does not include a machine system, there is an analog of the no-cloning theorem for classical systems. However, upon adjoining a non-trivial machine system (or ancilla) one finds that, pace the quantum case, the obstruction to cloning disappears for pure states. We begin by discussing some conceptual points and category-theoretic generalities having to do with cloning, and proceed to discuss no-cloning in both the case of (non-statistical) classical mechanics and classical statistical mechanics.

  7. Zinc Leaching from Tire Crumb Rubber

    NASA Astrophysics Data System (ADS)

    Rhodes, E. P.; Ren, J.; Mays, D. C.

    2010-12-01

    Recent estimates indicate that more than 2 billion scrap tires are currently stockpiled in the United States and approximately 280 million more tires are added annually. Various engineering applications utilize recycled tires in the form of shredded tire crumb rubber. However, the use of tire crumb rubber may have negative environmental impacts, especially when the rubber comes into contact with water. A review of the literature indicates that leaching of zinc from tire crumb rubber is the most significant water quality concern associated with using this material. Zinc is generally used in tire manufacturing, representing approximately 1.3% of the final product by mass. This study will report results from the U.S. Environmental Protection Agency’s (EPA’s) Synthetic Precipitation Leaching Procedure, batch leaching tests, and column leaching tests performed to quantify the process by which zinc leaches from tire crumb rubber into water. Results are interpreted with a first-order kinetic attachment/detachment model, implemented with the U.S. Agricultural Research Service software HYDRUS-1D, in order to determine the circumstances when zinc leaching from tire crumb rubber would be expected to comply with the applicable discharge limits. One potential application for recycled tires is replacing sand with tire crumb rubber in granular media filters used for stormwater pollution control. For this to be a viable application, the total zinc in the stormwater discharge must be below the EPA’s benchmark value of 0.117 mg/L.

  8. Development of rubber-enriched dandelion varieties by metabolic engineering of the inulin pathway.

    PubMed

    Stolze, Anna; Wanke, Alan; van Deenen, Nicole; Geyer, Roland; Prüfer, Dirk; Schulze Gronover, Christian

    2016-11-25

    Natural rubber (NR) is an important raw material for a large number of industrial products. The primary source of NR is the rubber tree Hevea brasiliensis, but increased worldwide demand means that alternative sustainable sources are urgently required. The Russian dandelion (Taraxacum koksaghyz Rodin) is such an alternative because large amounts of NR are produced in its root system. However, rubber biosynthesis must be improved to develop T. koksaghyz into a commercially feasible crop. In addition to NR, T. koksaghyz also produces large amounts of the reserve carbohydrate inulin, which is stored in parenchymal root cell vacuoles near the phloem, adjacent to apoplastically separated laticifers. In contrast to NR, which accumulates throughout the year even during dormancy, inulin is synthesized during the summer and is degraded from the autumn onwards when root tissues undergo a sink-to-source transition. We carried out a comprehensive analysis of inulin and NR metabolism in T. koksaghyz and its close relative T. brevicorniculatum and functionally characterized the key enzyme fructan 1-exohydrolase (1-FEH), which catalyses the degradation of inulin to fructose and sucrose. The constitutive overexpression of Tk1-FEH almost doubled the rubber content in the roots of two dandelion species without any trade-offs in terms of plant fitness. To our knowledge, this is the first study showing that energy supplied by the reserve carbohydrate inulin can be used to promote the synthesis of NR in dandelions, providing a basis for the breeding of rubber-enriched varieties for industrial rubber production.

  9. The Clone Factory

    ERIC Educational Resources Information Center

    Stoddard, Beryl

    2005-01-01

    Have humans been cloned? Is it possible? Immediate interest is sparked when students are asked these questions. In response to their curiosity, the clone factory activity was developed to help them understand the process of cloning. In this activity, students reenact the cloning process, in a very simplified simulation. After completing the…

  10. The Clone Factory

    ERIC Educational Resources Information Center

    Stoddard, Beryl

    2005-01-01

    Have humans been cloned? Is it possible? Immediate interest is sparked when students are asked these questions. In response to their curiosity, the clone factory activity was developed to help them understand the process of cloning. In this activity, students reenact the cloning process, in a very simplified simulation. After completing the…

  11. Use of Scrap Rubber in Asphalt Pavement Surfaces

    DTIC Science & Technology

    1991-12-01

    DEVELOPMENT OF method is conducted by applying compressive loads RUBBER -AGGREGATE with a prescribed sinusoidal waveform and can be used ASPHALT CONCRETE...evaluation program of rubber -aggregate as- 104 phalt surfaces with rubber contents from I to 3% rubber by weight is currently being conducted by the California...Transportation reports using as- men. However, no relationship between the modulus of phalt containing up to 25% crumb rubber (Civil Engi- resiliency and the

  12. Crumb Rubber-Concrete Panels Under Blast Loads

    DTIC Science & Technology

    2010-05-01

    AFRL-RX-TY-TP-2010-0052 CRUMB RUBBER -CONCRETE PANELS UNDER BLAST LOADS PREPRINT Bryan T. Bewick Air Force Research Laboratory 139...JAN-2009 -- 12-MAY-2010 Crumb Rubber -Concrete Panels Under Blast Loads FA4819-09-C-0032 62102F 4918 F0 Q210FA72 *Bewick, Bryan T.; #Salim, Hani A...those without any rubber . concrete; crumb rubber ; energy absorption; static resistance; blast U U U UU 14 Paul Sheppard Reset 1 Crumb Rubber

  13. Metabolic routes affecting rubber biosynthesis in Hevea brasiliensis latex

    PubMed Central

    Chow, Keng-See; Mat-Isa, Mohd.-Noor; Bahari, Azlina; Ghazali, Ahmad-Kamal; Alias, Halimah; Mohd.-Zainuddin, Zainorlina; Hoh, Chee-Choong; Wan, Kiew-Lian

    2012-01-01

    The cytosolic mevalonate (MVA) pathway in Hevea brasiliensis latex is the conventionally accepted pathway which provides isopentenyl diphosphate (IPP) for cis-polyisoprene (rubber) biosynthesis. However, the plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway may be an alternative source of IPP since its more recent discovery in plants. Quantitative RT-PCR (qRT-PCR) expression profiles of genes from both pathways in latex showed that subcellular compartmentalization of IPP for cis-polyisoprene synthesis is related to the degree of plastidic carotenoid synthesis. From this, the occurrence of two schemes of IPP partitioning and utilization within one species is proposed whereby the supply of IPP for cis-polyisoprene from the MEP pathway is related to carotenoid production in latex. Subsequently, a set of latex unique gene transcripts was sequenced and assembled and they were then mapped to IPP-requiring pathways. Up to eight such pathways, including cis-polyisoprene biosynthesis, were identified. Our findings on pre- and post-IPP metabolic routes form an important aspect of a pathway knowledge-driven approach to enhancing cis-polyisoprene biosynthesis in transgenic rubber trees. PMID:22162870

  14. A lettuce (Lactuca sativa) homolog of human Nogo-B receptor interacts with cis-prenyltransferase and is necessary for natural rubber biosynthesis.

    PubMed

    Qu, Yang; Chakrabarty, Romit; Tran, Hue T; Kwon, Eun-Joo G; Kwon, Moonhyuk; Nguyen, Trinh-Don; Ro, Dae-Kyun

    2015-01-23

    Natural rubber (cis-1,4-polyisoprene) is an indispensable biopolymer used to manufacture diverse consumer products. Although a major source of natural rubber is the rubber tree (Hevea brasiliensis), lettuce (Lactuca sativa) is also known to synthesize natural rubber. Here, we report that an unusual cis-prenyltransferase-like 2 (CPTL2) that lacks the conserved motifs of conventional cis-prenyltransferase is required for natural rubber biosynthesis in lettuce. CPTL2, identified from the lettuce rubber particle proteome, displays homology to a human NogoB receptor and is predominantly expressed in latex. Multiple transgenic lettuces expressing CPTL2-RNAi constructs showed that a decrease of CPTL2 transcripts (3-15% CPTL2 expression relative to controls) coincided with the reduction of natural rubber as low as 5%. We also identified a conventional cis-prenyltransferase 3 (CPT3), exclusively expressed in latex. In subcellular localization studies using fluorescent proteins, cytosolic CPT3 was relocalized to endoplasmic reticulum by co-occurrence of CPTL2 in tobacco and yeast at the log phase. Furthermore, yeast two-hybrid data showed that CPTL2 and CPT3 interact. Yeast microsomes containing CPTL2/CPT3 showed enhanced synthesis of short cis-polyisoprenes, but natural rubber could not be synthesized in vitro. Intriguingly, a homologous pair CPTL1/CPT1, which displays ubiquitous expressions in lettuce, showed a potent dolichol biosynthetic activity in vitro. Taken together, our data suggest that CPTL2 is a scaffolding protein that tethers CPT3 on endoplasmic reticulum and is necessary for natural rubber biosynthesis in planta, but yeast-expressed CPTL2 and CPT3 alone could not synthesize high molecular weight natural rubber in vitro.

  15. A Lettuce (Lactuca sativa) Homolog of Human Nogo-B Receptor Interacts with cis-Prenyltransferase and Is Necessary for Natural Rubber Biosynthesis*

    PubMed Central

    Qu, Yang; Chakrabarty, Romit; Tran, Hue T.; Kwon, Eun-Joo G.; Kwon, Moonhyuk; Nguyen, Trinh-Don; Ro, Dae-Kyun

    2015-01-01

    Natural rubber (cis-1,4-polyisoprene) is an indispensable biopolymer used to manufacture diverse consumer products. Although a major source of natural rubber is the rubber tree (Hevea brasiliensis), lettuce (Lactuca sativa) is also known to synthesize natural rubber. Here, we report that an unusual cis-prenyltransferase-like 2 (CPTL2) that lacks the conserved motifs of conventional cis-prenyltransferase is required for natural rubber biosynthesis in lettuce. CPTL2, identified from the lettuce rubber particle proteome, displays homology to a human NogoB receptor and is predominantly expressed in latex. Multiple transgenic lettuces expressing CPTL2-RNAi constructs showed that a decrease of CPTL2 transcripts (3–15% CPTL2 expression relative to controls) coincided with the reduction of natural rubber as low as 5%. We also identified a conventional cis-prenyltransferase 3 (CPT3), exclusively expressed in latex. In subcellular localization studies using fluorescent proteins, cytosolic CPT3 was relocalized to endoplasmic reticulum by co-occurrence of CPTL2 in tobacco and yeast at the log phase. Furthermore, yeast two-hybrid data showed that CPTL2 and CPT3 interact. Yeast microsomes containing CPTL2/CPT3 showed enhanced synthesis of short cis-polyisoprenes, but natural rubber could not be synthesized in vitro. Intriguingly, a homologous pair CPTL1/CPT1, which displays ubiquitous expressions in lettuce, showed a potent dolichol biosynthetic activity in vitro. Taken together, our data suggest that CPTL2 is a scaffolding protein that tethers CPT3 on endoplasmic reticulum and is necessary for natural rubber biosynthesis in planta, but yeast-expressed CPTL2 and CPT3 alone could not synthesize high molecular weight natural rubber in vitro. PMID:25477521

  16. Wear Resistant Rubber Tank Track Pads

    DTIC Science & Technology

    1975-10-01

    100 lignin: rubber latex coprecipitates (National Research Council of Canada), Duoform 3/4 inch fiber wire (National Standards Co.)» brass-plated...i • {■ «IT \\£P»* ■ . R-TR-T6-028 WEAR RESISTANT RUBBER TANK TRACK PADS \\ ■ ■ ■. by EDWARD W. BERGSTROM OCTOBER 1975 D D C...im»>nii»> WEAR RESISTANT RUBBER TANK TRACK PADS.j ’■ ? - » * .s. ————— A Edward W./Bergstrom 9. PERFORMING ORGANIZATION

  17. Analysis of rubber supply in Sri Lanka

    SciTech Connect

    Hartley, M.J.; Nerlove, M.; Peters, R.K. Jr.

    1987-11-01

    An analysis of the supply response for perennial crops is undertaken for rubber in Sir Lanka, focusing on the uprooting-replanting decision and disaggregating the typical reduced-form supply response equation into several structural relationships. This approach is compared and contrasted with Dowling's analysis of supply response for rubber in Thailand, which is based upon a sophisticated reduced-form supply function developed by Wickens and Greenfield for Brazilian coffee. Because the uprooting-replanting decision is central to understanding rubber supply response in Sri Lanka and for other perennial crops where replanting activities dominate new planting, the standard approaches do not adequately capture supply response.

  18. Chemistry of rubber processing and disposal.

    PubMed Central

    Bebb, R L

    1976-01-01

    The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis. PMID:799964

  19. Thermal properties of hydrogenated liquid natural rubber

    NASA Astrophysics Data System (ADS)

    Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-01

    Natural rubber (NR) was modified to form liquid natural rubber (LNR) via photooxidative degradation. Hydrogenated liquid natural rubber (HLNR) was synthesized by using diimide as source of hydrogen which the diimide is produced by thermolysis of p-toluenesulfonyl hydrazide (TSH). The structure of HLNR was characterized by determining the changes of main peaks in Fourier Transform infrared and nuclear magnetic resonance spectra after hydrogenation. Thermogravimetric analysis showed that the HLNR had higher decomposition temperature compared to LNR and the decomposition temperature is directly proportional to the percentage of conversion.

  20. Fatigue life of automotive rubber jounce bumper

    NASA Astrophysics Data System (ADS)

    Sidhu, R. S.; Ali, Aidy

    2010-05-01

    It is evident that most rubber components in the automotive industry are subjected to repetitive loading. Vigorous research is needed towards improving the safety and reliability of the components. The study was done on an automotive rubber jounce bumper with a rubber hardness of 60 IRHD. The test was conducted in displacement-controlled environment under compressive load. The existing models by Kim, Harbour, Woo and Li were adopted to predict the fatigue life. The experimental results show strong similarities with the predicted models.

  1. Thermal properties of hydrogenated liquid natural rubber

    SciTech Connect

    Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-25

    Natural rubber (NR) was modified to form liquid natural rubber (LNR) via photooxidative degradation. Hydrogenated liquid natural rubber (HLNR) was synthesized by using diimide as source of hydrogen which the diimide is produced by thermolysis of p-toluenesulfonyl hydrazide (TSH). The structure of HLNR was characterized by determining the changes of main peaks in Fourier Transform infrared and nuclear magnetic resonance spectra after hydrogenation. Thermogravimetric analysis showed that the HLNR had higher decomposition temperature compared to LNR and the decomposition temperature is directly proportional to the percentage of conversion.

  2. Recycling rubber wastes. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1996-04-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  3. Micromorphological characterization and label-free quantitation of small rubber particle protein in natural rubber latex.

    PubMed

    Wang, Sai; Liu, Jiahui; Wu, Yanxia; You, Yawen; He, Jingyi; Zhang, Jichuan; Zhang, Liqun; Dong, Yiyang

    2016-04-15

    Commercial natural rubber is traditionally supplied by Hevea brasiliensis, but now there is a big energy problem because of the limited resource and increasing demand. Intensive study of key rubber-related substances is urgently needed for further research of in vitro biosynthesis of natural rubber. Natural rubber is biosynthesized on the surface of rubber particles. A membrane protein called small rubber particle protein (SRPP) is a key protein associated closely with rubber biosynthesis; however, SRPP in different plants has been only qualitatively studied, and there are no quantitative reports so far. In this work, H. brasiliensis was chosen as a model plant. The microscopic distribution of SRPP on the rubber particles during the washing process was investigated by transmission electron microscopy-immunogold labeling. A label-free surface plasmon resonance (SPR) immunosensor was developed to quantify SRPP in H. brasiliensis for the first time. The immunosensor was then used to rapidly detect and analyze SRPP in dandelions and prickly lettuce latex samples. The label-free SPR immunosensor can be a desirable tool for rapid quantitation of the membrane protein SRPP, with excellent assay efficiency, high sensitivity, and high specificity. The method lays the foundation for further study of the functional relationship between SRPP and natural rubber content.

  4. Characterization of rubber particles and rubber chain elongation in Taraxacum koksaghyz

    PubMed Central

    2010-01-01

    Background Natural rubber is a biopolymer with exceptional qualities that cannot be completely replaced using synthetic alternatives. Although several key enzymes in the rubber biosynthetic pathway have been isolated, mainly from plants such as Hevea brasiliensis, Ficus spec. and the desert shrub Parthenium argentatum, there have been no in planta functional studies, e.g. by RNA interference, due to the absence of efficient and reproducible protocols for genetic engineering. In contrast, the Russian dandelion Taraxacum koksaghyz, which has long been considered as a potential alternative source of low-cost natural rubber, has a rapid life cycle and can be genetically transformed using a simple and reliable procedure. However, there is very little molecular data available for either the rubber polymer itself or its biosynthesis in T. koksaghyz. Results We established a method for the purification of rubber particles - the active sites of rubber biosynthesis - from T. koksaghyz latex. Photon correlation spectroscopy and transmission electron microscopy revealed an average particle size of 320 nm, and 13C nuclear magnetic resonance (NMR) spectroscopy confirmed that isolated rubber particles contain poly(cis-1,4-isoprene) with a purity >95%. Size exclusion chromatography indicated that the weight average molecular mass (w) of T. koksaghyz natural rubber is 4,000-5,000 kDa. Rubber particles showed rubber transferase activity of 0.2 pmol min-1 mg-1. Ex vivo rubber biosynthesis experiments resulted in a skewed unimodal distribution of [1-14C]isopentenyl pyrophosphate (IPP) incorporation at a w of 2,500 kDa. Characterization of recently isolated cis-prenyltransferases (CPTs) from T. koksaghyz revealed that these enzymes are associated with rubber particles and are able to produce long-chain polyprenols in yeast. Conclusions T. koksaghyz rubber particles are similar to those described for H. brasiliensis. They contain very pure, high molecular mass poly(cis-1,4-isoprene) and

  5. Rubber compositions for hydrazine service

    NASA Technical Reports Server (NTRS)

    Repar, J.

    1973-01-01

    Forty-three compounds were formulated and tested for physical properties and hydrazine compatibility. Variables introduced include silicon dioxide filler loading level and particle size. Both butyl and ethylene-propylene rubbers were employed as well as various vulcanization systems. The data showed that compounds containing butyl and butyl blended with ethylene propylene could not be distinguished from ethylene propylene alone as far as chemical properties were concerned. A trend noted was that a filler level with higher silicon dioxide loading exhibited better hydrazine compatibility. Particle size variation did not show any consistent trends. Any of the vulcanization systems employed appeared to be satisfactory. A refined technique for dissolving aluminum cores from EPT-10 bladders was also tested.

  6. Aboveground biomass, wood volume, nutrient stocks and leaf litter in novel forests compared to native forests and tree plantations in Puerto Rico

    Treesearch

    A.E. Lugo; O. Abelleira Martínez; J. Fonseca da Silva

    2012-01-01

    The article presents comparative data for aboveground biomass, wood volume, nutirent stocks (N, P, K) and leaf litter in different types of forests in Puerto Rico. The aim of the study is to assess how novel forests of Castilla elastica, Panama Rubber Tree, and Spathodea campanulata, African Tulip Tree, compare with tree plantations and native historical forests (both...

  7. High frequency testing of rubber mounts.

    PubMed

    Vahdati, Nader; Saunders, L Ken Lauderbaugh

    2002-04-01

    Rubber and fluid-filled rubber engine mounts are commonly used in automotive and aerospace applications to provide reduced cabin noise and vibration, and/or motion accommodations. In certain applications, the rubber mount may operate at frequencies as high as 5000 Hz. Therefore, dynamic stiffness of the mount needs to be known in this frequency range. Commercial high frequency test machines are practically nonexistent, and the best high frequency test machine on the market is only capable of frequencies as high as 1000 Hz. In this paper, a high frequency test machine is described that allows test engineers to study the high frequency performance of rubber mounts at frequencies up to 5000 Hz.

  8. Oils and rubber from arid land plants

    NASA Astrophysics Data System (ADS)

    Johnson, J. D.; Hinman, C. W.

    1980-05-01

    In this article the economic development potentials of Cucurbita species (buffalo gourd and others), Simmondsia chinensis (jojoba), Euphorbia lathyris (gopher plant), and Parthenium argentatum (guayule) are discussed. All of these plants may become important sources of oils or rubber.

  9. Visual evoked potentials in rubber factory workers.

    PubMed

    Tandon, O P; Kumar, V

    1997-01-01

    Pattern reversal visual evoked potentials (pVEP) were studied in 39 male rubber factory workers in the age range of 18-55 years and 20 control subjects (aged 18-46 years) not exposed to the rubber factory environment. Results revealed that 20 (51%) rubber factory workers had abnormal latencies of wave P1 (dominant component of pVEP) as per accepted criteria of 99% tolerance limit set for the control group (i.e. any value above mean +3 SD of control was considered abnormal). The section-wise per cent distribution of abnormalities was vulcanization (83%), tubing (75%), calendering (60%), loading (38%) and mixing (14%). This study provides electrophysiological evidence that rubber factory environments affect the conduction processes in optical pathways from their origin in the retina to striate cortex. However, this study has its limitations in not identifying the specific chemical(s) causing these changes in VEP.

  10. Plastics and Rubber Products Manufacturing (NAICS 326)

    EPA Pesticide Factsheets

    Find environmental regulatory and compliance information for plastics and rubber products manufacturing (which includes the manufacture of cellulose and other fibers) including information about NESHAPs and effluent guidelines for wastewater discharges

  11. Allergic reaction after rubber dam placement.

    PubMed

    de Andrade, E D; Ranali, J; Volpato, M C; de Oliveira, M M

    2000-03-01

    In the last few years allergic reactions to natural rubber latex (NRL) have increased in dental practice affecting both the dental team and patients. Some case reports discuss the potential risks of hypersensitivity to NRL products. An adverse patient reaction after dental rubber dam placement is reported. About 1 min after the isolation of the tooth with a rubber dam the patient presented signs and symptoms of hypersensitivity. Oxygen and intravenous hydrocortisone were administered and the patient kept under observation. After 2 h she had stable vital signs and no more allergics symptoms. It is unclear whether components of the NRL dam or the cornstarch powder incorporated with the rubber dam was responsible for the allergic reaction. Dentists must be aware of the health problem and be prepared for an adequate management in dental practice.

  12. [Total analysis of organic rubber additives].

    PubMed

    He, Wen-Xuan; Robert, Shanks; You, Ye-Ming

    2010-03-01

    In the present paper, after middle pressure chromatograph separation using both positive phase and reversed-phase conditions, the organic additives in ethylene-propylene rubber were identified by infrared spectrometer. At the same time, by using solid phase extraction column to maintain the main component-fuel oil in organic additves to avoid its interfering with minor compounds, other organic additves were separated and analysed by GC/Ms. In addition, the remaining active compound such as benzoyl peroxide was identified by CC/Ms, through analyzing acetone extract directly. Using the above mentioned techniques, soften agents (fuel oil, plant oil and phthalte), curing agent (benzoylperoxide), vulcanizing accelerators (2-mercaptobenzothiazole, ethyl thiuram and butyl thiuram), and antiagers (2, 6-Di-tert-butyl-4-methyl phenol and styrenated phenol) in ethylene-propylene rubber were identified. Although the technique was established in ethylene-propylene rubber system, it can be used in other rubber system.

  13. The rubber plantation environment and Lassa fever epidemics in Liberia, 2008-2012: a spatial regression.

    PubMed

    Olugasa, Babasola O; Dogba, John B; Ogunro, Bamidele; Odigie, Eugene A; Nykoi, Jomah; Ojo, Johnson F; Taiwo, Olalekan; Kamara, Abraham; Mulbah, Charles K; Fasunla, Ayotunde J

    2014-10-01

    As Lassa fever continues to be a public health challenge in West Africa, it is critical to produce good maps of its risk pattern for use in active surveillance and control intervention. We identified eight spatial features related to the rubber plantation environment and used them as explanatory variables for Lassa fever (LF) outbreaks on the Uniroyal Liberian Agricultural Company (LAC) rubber plantation environment in Grand Bassa County, Liberia. We computed classical and spatial lag regression models on all spatial features, including proximity of residential camp to rubber tree-edge, main road in the plantation, LAC hospital, rice farmland, household refuse dump, human population density, post-harvest storage density of rice and density of rodent deterrent on rice storage. We found significant (p=0.0024) spatial autocorrelation between LF cases and the spatial features we have considered. We concluded that the rubber plantation environment influenced Mastomys species' breeding and transmission of Lassa virus along spatial scale to humans. The risk factors identified in this study offered a baseline for more effective surveillance and control of LF in the post-civil conflict Liberia.

  14. Adaptive Process Control in Rubber Industry.

    PubMed

    Brause, Rüdiger W; Pietruschka, Ulf

    1998-01-01

    This paper describes the problems and an adaptive solution for process control in rubber industry. We show that the human and economical benefits of an adaptive solution for the approximation of process parameters are very attractive. The modeling of the industrial problem is done by the means of artificial neural networks. For the example of the extrusion of a rubber profile in tire production our method shows good resuits even using only a few training samples.

  15. [Detection of pentachlorophenol in natural rubber latex].

    PubMed

    Jaworska, E

    1976-01-01

    The method of detection of pentachlorophenol in natural rubber latex is proposed. Pentachlorophenol is isolated from other nonrubber-like substances by thin-layer chromatography and identified by spectroscopic method in UV-light. Isolation of pentachlorophenol is carried out from water extracts obtained from the dry caoutchouc films, so the same method can be used for examination of the rubber articles designed for the medicinetoo.

  16. Fatigue, Fracture and Wear Properties of Rubber

    DTIC Science & Technology

    1989-01-19

    gregates and rubber molecules: Wc-[ -ACPcr (filled)/ ACpa m (filled)]*(1-v), (6) where v is the fraction of bound rubber which could be determined by20 v - 1...ACPcr / ACPa m ) *(l-0) (A Tic /AH TIC , o ) +( AHSIC /AHsI C 1 4 )( in which AH TIC oo- 64.1 J/gm (15.3 cal/gm)2 ., AHTIC (Figure 4b), AHSI C (Figure 5

  17. Biochemical and spectroscopic characterization of purified Latex Clearing Protein (Lcp) from newly isolated rubber degrading Rhodococcus rhodochrous strain RPK1 reveals novel properties of Lcp.

    PubMed

    Watcharakul, Sirimaporn; Röther, Wolf; Birke, Jakob; Umsakul, Kamontam; Hodgson, Brian; Jendrossek, Dieter

    2016-05-23

    Biodegradation of rubber (polyisoprene) is initiated by oxidative cleavage of the polyisoprene backbone and is performed either by an extracellular rubber oxygenase (RoxA) from Gram-negative rubber degrading bacteria or by a latex clearing protein (Lcp) secreted by Gram-positive rubber degrading bacteria. Only little is known on the biochemistry of polyisoprene cleavage by Lcp and on the types and functions of the involved cofactors. A rubber-degrading bacterium was isolated from the effluent of a rubber-processing factory and was taxonomically identified as a Rhodococcus rhodochrous species. A gene of R. rhodochrous RPK1 that coded for a polyisoprene-cleaving latex clearing protein (lcp Rr ) was identified, cloned, expressed in Escherichia coli and purified. Purified LcpRr had a specific activity of 3.1 U/mg at 30 °C and degraded poly(1,4-cis-isoprene) to a mixture of oligoisoprene molecules with terminal keto and aldehyde groups. The pH optimum of LcpRr was higher (pH 8) than for other rubber-cleaving enzymes (≈ pH 7). UVvis spectroscopic analysis of LcpRr revealed a cytochrome-specific absorption spectrum with an additional feature at long wavelengths that has not been observed for any other rubber-cleaving enzyme. The presence of one b-type haem in LcpRr as a co-factor was confirmed by (i) metal analysis, (ii) solvent extraction, (iii) bipyridyl assay and (iv) detection of haem-b specific m/z values via mass-spectrometry. Our data point to substantial differences in the active sites of Lcp proteins obtained from different rubber degrading bacteria.

  18. Rubber linings -- Overview and new technology

    SciTech Connect

    Mehra, L.; Polaski, E.L.; Lewis, R.K.; Mauri, A.

    1995-12-01

    The authors have covered at some length the basic steps involved in rubber lining. They have talked about the progress made in adhesives for lining. The new system in use now is far superior to previous systems. The new systems and the developments going on towards water-based adhesives are discussed. The authors briefly brought up the various types of rubber materials and new developments in terms of chlorobutyl-faced three-ply rubbers as well as development of EPDM-based compounds in Europe. The methods of vulcanization used have been discussed, including hot air vulcanizing which is prevalent in Europe. The development of self-vulcanizing rubber and the advantages in use of pre-cured rubber have been described. The development of new methods, techniques and products for rubber lining has been slow but sure. As can be expected, new product development costs are huge, requiring expert attention and participation. The possibilities are limitless and effort is forthcoming from various sources. There is a need for an interchange of ideas, and the involvement of NACE International and other professional bodies is acknowledged and appreciated.

  19. Simulation of a rubber plantation productivity in central Cambodia using the individual-based dynamic vegetation model SEIB-DGVM

    NASA Astrophysics Data System (ADS)

    Kumagai, T.; SATO, H.; Shinjiro, Ph. D., F.

    2013-12-01

    To provide a useful tool for building strategy of forest plantation management, we developed the Spatially Explicit Individual-Based (SEIB) Dynamic Global Vegetation Model (DGVM) applicable to simulate productivity of tree plantations (SEIB-PP). Rubber (Hevea brasiliensis Müll. Arg.) plantations, which are rapidly expanding into both climatically optimal and sub-optimal environments throughout mainland Southeast Asia, potentially change the partitioning of water, energy, and carbon at multiple scales, compared with traditional land covers that are being replaced. Describing both primary and latex productivities in rubber plantations via SEIB-PP is, therefore, important to understanding the climatic impacts on productive processes. Model results are compared with measurements collected at a field site in central Cambodia, and here, we show some examples of projections: the rubber plantation production under future climate change conditions.

  20. [Genetic polymorphism of clones and their seed progeny in the scotch pine clone plantation].

    PubMed

    Korshikov, I I; Demkovich, A E

    2010-01-01

    Genetic variation at 12 allozyme loci (10 of them being polymorphic ones) has been studied in the archive-clone plantation of 23 Pinus sylvestris plus-trees and their seed progeny in the south-east of Ukraine. More than a half of clones had 4-8 heterozygous loci, whereas their seed progeny was marked by a lower variation than maternal trees. Seed progeny was obtained at a high outcrossing rate (t(m) = 95%). The clone progeny was characterized by a high percentage of abnormal allele segregation in megagametophytes. There was also a high frequency of significant deviation in distribution of seed embryo genotypes from the theoretically expected one according to the Hardy-Weinberg law.

  1. Use of waste rubber as concrete additive.

    PubMed

    Chou, Liang Hsing; Lu, Chun-Ku; Chang, Jen-Ray; Lee, Maw Tien

    2007-02-01

    For resource reutilization, scrap tyres have long been investigated as an additive to concrete to form 'Rubcrete' for various applications and have shown promising results. However, the addition of rubber particles leads to the degradation of physical properties, particularly, the compressive strength of the concrete. In this study, a theoretical model was proposed to shed light on the mechanisms of decrease in compressive strength due to the addition of rubber particles as well as improvement in compressive strength through modification of particle surfaces. The literature suggests that the compressive strength can be improved by soaking the rubber particles in alkaline solution first to increase the inter-phase bonding between the rubber particles and cement. Instead, we discovered that the loss in compressive strength was due to local imperfections in the hydration of cement, induced by the addition of heterogeneous and hydrophobic rubber particles. Microscopic studies showed that the rubber particles disturbed the water transfer to create channels, which were prone to cracking and led to a loss in the compressive strength. Unexpectedly, no cracking was found along the surfaces of the rubber particles, indicating that the bonding strength between the rubber particles and cement phases was not the critical factor in determining the compressive strength. Therefore, a theoretical model was proposed to describe the water transfer in the Rubcrete specimens to explain the experimental data. In the model, the local water available for hydration (Q) is: Q = -A(slv)/6piv, where Q, A(slv), and v are mass flow rate (kg s(-1)), Hamaker constant (J), and dynamic viscosity (m2 s(-1)), respectively. By maximizing the quantity Q and, in turn, the Hamaker constant A(slv), the compressive strength could be improved. The Hamaker constant A(slv) for water film on rubber particle surfaces was smaller than that for the hydrated cement particles; the water transfer rate was lower in

  2. How Do Rubber (Hevea brasiliensis) Plantations Cope with Seasonal Drought in Northern Thailand and Central Cambodia?

    NASA Astrophysics Data System (ADS)

    Kumagai, T.; Giambelluca, T. W.

    2014-12-01

    Rubber (Hevea brasiliensis Müll. Arg.) plantaitons are rapidly expanding throughout mainland Southeast Asia, potentially changing the partitioning of water, energy, and carbon at multiple scales, compared with the traditional land covers they are replacing. We have conducted eddy flux measurements in two rubber plantation sites: Som Sanuk (SS), located northern Thailand; and Cambodian Rubber Research Institute (CRRI), central Cambodia. We used combination of actual evapotranspiration (ET) flux measurements and an inversed version of a simple 2-layer ET model for estimating the mean canopy stomatal conductances (gs), which is among the most effective measures for describing the exchange characteristics. It is demonstrated how each studied rubber plantation copes with each strong seasonal drought via tree water use strategies. Potential tree water use deficit (precipitation (P) - potential evaporation (ET_POT)) for each season (i.e., December-February: DJF, March-May: MAM, June-August: JJA, and September-November: SON) revealed in which season and how the water use should be controlled. We found that in the season when actual tree water use deficit (P - ET) was negative (DJF and MAM), the deficit was compensated with soil water from the previous season at a depth of 0-2 m at the Thailand site, and from a depth of 0-3 m at CRRI. Two ecophysiological parameters, the reference value of gs (gsref) and the sensitivity of gs to atmospheric demand (m), as well as their proportionality (m/gsref), were derived from the logarithmic response curve of gs to vapor pressure deficit (D) for each season and each site. In both sites, gsref and m appeared to be less in DJF and MAM than each in the other three month periods (seasons). On average in a whole year, m/gsref was less than 0.6 at SS and almost 0.6 at the CRRI site, suggesting that there was less sufficient stomatal regulation at SS, where there might be little risk of water stress-induced hydraulic failure because of much

  3. Effect of non-rubber constituents on guayule and Hevea rubber intrinsic properties

    USDA-ARS?s Scientific Manuscript database

    To meet the increasing demand for natural rubber (NR), and address price volatility and steadily increasing labor costs, alternate rubber-producing species are in commercial development. One of these, guayule (Parthenium argentatum), has emerged on the market as a sustainable commercial source of h...

  4. Euphorbia characias latex: micromorphology of rubber particles and rubber transferase activity.

    PubMed

    Spanò, Delia; Pintus, Francesca; Esposito, Francesca; Loche, Danilo; Floris, Giovanni; Medda, Rosaria

    2015-02-01

    We have recently characterized a natural rubber in the latex of Euphorbia characias. Following that study, we here investigated the rubber particles and rubber transferase in that Mediterranean shrub. Rubber particles, observed by scanning electron microscopy, are spherical in shape with diameter ranging from 0.02 to 1.2 μm. Washed rubber particles exhibit rubber transferase activity with a rate of radiolabeled [(14)C]IPP incorporation of 4.5 pmol min(-1)mg(-1). Denaturing electrophoresis profile of washed rubber particles reveals a single protein band of 37 kDa that is recognized in western blot analysis by antibodies raised against the synthetic peptide whose sequence, DVVIRTSGETRLSNF, is included in one of the five regions conserved among cis-prenyl chain elongation enzymes. The cDNA nucleotide sequence of E. characias rubber transferase (GenBank JX564541) and the deduced amino acid sequence appear to be highly homologous to the sequence of several plant cis-prenyltransferases.

  5. A calculation method for torsional vibration of a crankshafting system with a conventional rubber damper by considering rubber form

    SciTech Connect

    Kodama, Tomoaki; Honda, Yasuhiro; Wakabayashi, Katsuhiko; Iwamoto, Shoichi

    1996-09-01

    The cheap and compact rubber dampers of shear-type have been widely employed as the torsional vibration control of the crankshaft system of high-speed, automobile diesel engines. The conventional rubber dampers have various rubber forms owing to the thorough investigation of optimum dampers in the design stage. Their rubber forms can be generally grouped into three classes such as the disk type, the bush type and the composite type. The disk type and the bush type rubber dampers are called the basic-pattern rubber dampers hereafter. The composite type rubber part is supposed to consist of the disk type and the bush type parts, regarded respectively as the basic patterns of the rubber part, at large. The dynamic characteristics of the vibration isolator rubber depend generally on temperature, frequency, strain amplitude, shape and size effect,s so it is difficult to estimate accurately their characteristics. With the present technical level, it is also difficult to determine the suitable rubber geometry which optimizes the vibration control effect. The study refers to the calculation method of the torsional vibration of a crankshaft system with a shear-type rubber damper having various rubber forms in order to offer the useful method for optimum design. In this method, the rheological formula of the three-element Maxwell model, from which the torsional stiffness and the damping coefficient of the damper rubber part in the equivalent vibration system are obtained, are adopted in order to decide the dynamic characteristics of the damper rubber part.

  6. Combination biological and microwave treatments of used rubber products

    DOEpatents

    Fliermans, Carl B.; Wicks, George G.

    2002-01-01

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds altered by biotreatment with thermophillic microorganisms selected from natural isolates from hot sulfur springs. Following the biotreatment, microwave radiation is used to further treat the surface and to treat the bulk interior of the crumb rubber. The resulting combined treatments render the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels and sizes of the treated crumb rubber can be used in new rubber mixtures and good properties obtained from the new recycled products.

  7. Effects of methanol-to-oil ratio, catalyst amount and reaction time on the FAME yield by in situ transesterification of rubber seeds (Hevea brasiliensis)

    NASA Astrophysics Data System (ADS)

    Abdulkadir, Bashir Abubakar; Uemura, Yoshimitsu; Ramli, Anita; Osman, Noridah B.; Kusakabe, Katsuki; Kai, Takami

    2014-10-01

    In this research, biodiesel is produced by in situ transesterification (direct transesterification) method from the rubber seeds using KOH as a catalyst. The influence of methanol to seeds mass ratio, duration of reaction, and catalyst loading was investigated. The result shows that, the best ratio of seeds to methanol is 1:6 (10 g seeds with 60 g methanol), 120 minutes reaction time and catalyst loading of 3.0 g. The maximum FAME yield obtain was 70 %. This findings support FAME production from the seeds of rubber tree using direct transesterifcation method from the seeds of rubber tree as an alternative to diesel fuel. Also, significant properties of biodiesel such as cloud point, density, pour point, specific gravity, and viscosity were investigated.

  8. Multipartite asymmetric quantum cloning

    SciTech Connect

    Iblisdir, S.; Gisin, N.; Acin, A.; Cerf, N.J.; Filip, R.; Fiurasek, J.

    2005-10-15

    We investigate the optimal distribution of quantum information over multipartite systems in asymmetric settings. We introduce cloning transformations that take N identical replicas of a pure state in any dimension as input and yield a collection of clones with nonidentical fidelities. As an example, if the clones are partitioned into a set of M{sub A} clones with fidelity F{sup A} and another set of M{sub B} clones with fidelity F{sup B}, the trade-off between these fidelities is analyzed, and particular cases of optimal N{yields}M{sub A}+M{sub B} cloning machines are exhibited. We also present an optimal 1{yields}1+1+1 cloning machine, which is an example of a tripartite fully asymmetric cloner. Finally, it is shown how these cloning machines can be optically realized.

  9. Aristotle and headless clones.

    PubMed

    Mosteller, Timothy

    2005-01-01

    Cloned organisms can be genetically altered so that they do not exhibit higher brain functioning. This form of therapeutic cloning allows for genetically identical organs and tissues to be harvested from the clone for the use of the organism that is cloned. "Spare parts" cloning promises many opportunities for future medical advances. What is the ontological and ethical status of spare parts, headless clones? This paper attempts to answer this question from the perspective of Aristotle's view of the soul. Aristotle's metaphysics as applied to his view of biological essences generates an ethic that can contribute to moral reasoning regarding the use of headless spare parts clones. The task of this paper is to show the implications that Aristotle's view of the soul, if it is true, would have on the ethics of headless, spare parts cloning.

  10. Ethical issues in cloning.

    PubMed

    Satris, S

    2000-01-01

    There is great public concern with the ethics of human cloning. This paper briefly examines some of what I identify as pseudo-problems or myths associated with cloning, and some of the more substantial ethical concerns.

  11. Cloning in reproductive medicine.

    PubMed

    Illmensee, K

    2001-08-01

    This review article summarizes the historical development of mammalian cloning, presents current advances and presumed risk factors in the field of reproductive cloning, discusses possible clinical applications of therapeutic and diagnostic cloning and outlines prospective commercial trends in pharmaceutical cloning. Predictable progress in biotechnology and stem cell engineering should prove to be advantageous for patients' health and for novel benefits in reproductive and regenerative medicine.

  12. Microdissection and molecular manipulation of single chromosomes in woody fruit trees with small chromosomes using pomelo (Citrus grandis) as a model. II. Cloning of resistance gene analogs from single chromosomes.

    PubMed

    Huang, D; Wu, W; Lu, L

    2004-05-01

    Amplification of resistance gene analogs (RGAs) is both a useful method for acquiring DNA markers closely linked to disease resistance (R) genes and a potential approach for the rapid cloning of R genes in plants. However, the screening of target sequences from among the numerous amplified RGAs can be very laborious. The amplification of RGAs from specific chromosomes could greatly reduce the number of RGAs to be screened and, consequently, speed up the identification of target RGAs. We have developed two methods for amplifying RGAs from single chromosomes. Method 1 uses products of Sau3A linker adaptor-mediated PCR (LAM-PCR) from a single chromosome as the templates for RGA amplification, while Method 2 directly uses a single chromosomal DNA molecule as the template. Using a pair of degenerate primers designed on the basis of the conserved nucleotide-binding-site motifs in many R genes, RGAs were successfully amplified from single chromosomes of pomelo using both these methods. Sequencing and cluster analysis of RGA clones obtained from single chromosomes revealed the number, type and organization of R-gene clusters on the chromosomes. We suggest that Method 1 is suitable for analyzing chromosomes that are unidentifiable under a microscope, while Method 2 is more appropriate when chromosomes can be clearly identified.

  13. Elastic Fluctuations and Rubber Elasticity

    NASA Astrophysics Data System (ADS)

    Xing, Xiangjun; Goldbart, Paul; Rradzihovsky, Leo

    2006-03-01

    A coarse-grained phenomenological model is constructed to describe both phonon fluctuations and elastic heterogeneities in rubbery materials. It is a nonlocal, spatially heterogeneous generalization of the classical model of rubber elasticity, and with a tunable repulsion interaction. This model can also be derived from the Vulcanization theory. The residual stress and the non-affine deformation field, as well as their correlations, are calculated perturbatively, to the leading order of quenched randomness. It is explicitly shown that the interplay between the repulsive interaction and quenched randomness induces non- affine deformation. The spatial correlations of the non- affine deformation field and residual stress exhibit power-law scaling, with no characteristic length scale. We also calculate the contributions to the elastic free energy from both thermal and quenched fluctuations for arbitrary deformation. We find that they naturally explain the universal features in the Mooney-Rivlin plot of the stress-strain curve for rubbery materials. The (disorder averaged) thermal fluctuation of monomers is shown to depend on deformation, and becomes anisotropic upon shear deformation, as long as the repulsive interaction is finite.

  14. Talking Trees

    ERIC Educational Resources Information Center

    Tolman, Marvin

    2005-01-01

    Students love outdoor activities and will love them even more when they build confidence in their tree identification and measurement skills. Through these activities, students will learn to identify the major characteristics of trees and discover how the pace--a nonstandard measuring unit--can be used to estimate not only distances but also the…

  15. Talking Trees

    ERIC Educational Resources Information Center

    Tolman, Marvin

    2005-01-01

    Students love outdoor activities and will love them even more when they build confidence in their tree identification and measurement skills. Through these activities, students will learn to identify the major characteristics of trees and discover how the pace--a nonstandard measuring unit--can be used to estimate not only distances but also the…

  16. Tree Amigos.

    ERIC Educational Resources Information Center

    Center for Environmental Study, Grand Rapids, MI.

    Tree Amigos is a special cross-cultural program that uses trees as a common bond to bring the people of the Americas together in unique partnerships to preserve and protect the shared global environment. It is a tangible program that embodies the philosophy that individuals, acting together, can make a difference. This resource book contains…

  17. On Optimizing an Archibald Rubber-Band Heat Engine.

    ERIC Educational Resources Information Center

    Mullen, J. G.; And Others

    1978-01-01

    Discusses the criteria and procedure for optimizing the performance of Archibald rubber-band heat engines by using the appropriate choice of dimensions, minimizing frictional torque, maximizing torque and balancing the rubber band system. (GA)

  18. Evaluation of synergy in tire rubber-coal coprocessing

    SciTech Connect

    Mastral, A.M.; Mayoral, M.C.; Murillo, R.; Callen, M.; Garcia, T.; Tejero, M.P.; Torres, N.

    1998-09-01

    The tire rubber-coal synergy is evaluated through the different roles that rubber can have in coprocessing systems. For that, two different experimental designs were used: a swept fixed-bed reactor and tubing bomb minireactors. In this way, coal was coprocessed with rubber liquids from rubber pyrolysis and rubber hydrogenation, in a hydrogen atmosphere at 400 C. Coal was mixed as well with rubber in different proportions and hydrogenated at 375, 400, and 425 C, and oils obtained were characterized by thin-layer chromatography to obtain hydrocarbon type composition. Rubber behavior was compared to each of the main components of tires, and all the results indicated that the slight synergy found can be due to the small free radicals from vulcanized rubber decomposition, which are able to stabilize coal radicals to light products.

  19. On Optimizing an Archibald Rubber-Band Heat Engine.

    ERIC Educational Resources Information Center

    Mullen, J. G.; And Others

    1978-01-01

    Discusses the criteria and procedure for optimizing the performance of Archibald rubber-band heat engines by using the appropriate choice of dimensions, minimizing frictional torque, maximizing torque and balancing the rubber band system. (GA)

  20. Radiation degradation of spent butyl rubbers

    NASA Astrophysics Data System (ADS)

    Telnov, A. V.; Zavyalov, N. V.; Khokhlov, Yu. A.; Sitnikov, N. P.; Smetanin, M. L.; Tarantasov, V. P.; Shadrin, D. N.; Shorikov, I. V.; Liakumovich, A. L.; Miryasova, F. K.

    2002-03-01

    Radiation methods of materials modification applied in technological chains can have significant economical and ecological advantages as compared to the established chemical, thermal and mechanical methods. Each year the problems of nature resources economy through the use of production and consumption wastes acquire a more significant value, as it allows to solve also ecological issues along with economical ones. This is mostly acute in relation to polymeric systems based on saturated rubbers, for example butyl rubber (BR) used in the tyre industry, as due to their high resistance to the action of oxygen, ozone, solar radiation and bacteria, they contaminate the environment for rather a long period. At VNIIEF and KSPU experiments were carried out on application of electron beams with energy from 6 to 10 MeV for radiation destruction of spent rubber based on BR. The radiation-degraded material was tested for re-use in the formulation of initial diaphragm mixture, rubber mixture for producing rubberized fabric and roofing.

  1. New rubber qualification for the igniter adapter

    NASA Technical Reports Server (NTRS)

    Humpherys, Mark A.

    1994-01-01

    Kirkhill Rubber Company (KRC) has informed Thiokol Corporation that two raw materials used in the asbestos and silica filled acrylonitrile butadience rubber (NBR) formulation per STW 2621 are no longer available from their vendors. Agerite White (Di-beta-naphthyl-paraphenylene diamine), manufactured by B. F. Goodrich, is an antioxidant used in NBR. This raw material makes up roughly 1-2 percent of the finished product. KRC proposed that this raw material be replaced by Agerite Stalite S (mixture of octylated diphenylamines) distributed by R. T. Vanderbilt Co. Protox-166 zinc oxide, manufactured by Zinc Corporation of America, is an activator currently used in NBR. This material also makes up about 1-2 percent of the finished material. Protox-166 is an American process grade zinc oxide. It is proposed by KRC to replace Protox-166 with Kadox-930C, a French process grade zinc oxide. American process grades have an ASTM minimum purity of 99.0 percent; the French process grades have a minimum purity of 99.5 percent. Previous testing per WTP-0270 has demonstrated that the mechanical and thermal properties of the rubber with the new ingredients are comparable to the 'old' rubber. The test results are reported in TWR-61790. One igniter adapter, Part no. 7U77562-02 serial no. 2 was insulated per ETP-1206 using the new rubber formulation and a modified lay up and cure method to demonstrate that there is no impact on this process. The results of this demonstration are reported.

  2. Investigation of natural latex rubber gloves

    SciTech Connect

    Vessel, E.M.

    1993-03-19

    Seventy five percent of natural latex rubber gloves used in laboratories at the Savannah River Site are not reused. A cost analysis performed by the SRS Procurement Department determined that a net savings of $1,092,210 could be achieved annually by recycling latex rubber gloves. The Materials Technology Section, at the request of the Procurement Department, examined some mechanical and chemical properties of latex rubber gloves manufactured by Ansell Edmont, which had been purchased by the site specifications for protective clothing. It also examined mechanical properties of re-cycled gloves purchased by specifications and of {open_quotes}off the shelf{close_quotes} gloves manufactured by North Brothers Company. Finally, water vapor transmission studies, simulating tritium permeation, were performed on gloves from both manufacturers. These studies were performed to determine whether latex rubber gloves can be recycled or whether using only new, unwashed gloves is required in areas where tritium exposure is a possibility. The results of these studies indicate that the acceptable glove characteristics, required in the WSRC Manual 5Q1.11, Protective Clothing Specifications, are not adversely affected after washing and drying the gloves manufactured by Ansell Edmont for seven cycles. Results also indicate that natural latex rubber gloves manufactured by North Brothers comply with most of the acceptable glove characteristics specified in the WSRC Manual 5Q1.11. Statistical analysis of the water vapor permeation data show that there is no correlation between permeation rates and the manufacturer.

  3. Clone history shapes Populus drought responses

    PubMed Central

    Raj, Sherosha; Bräutigam, Katharina; Hamanishi, Erin T.; Wilkins, Olivia; Thomas, Barb R.; Schroeder, William; Mansfield, Shawn D.; Plant, Aine L.; Campbell, Malcolm M.

    2011-01-01

    Just as animal monozygotic twins can experience different environmental conditions by being reared apart, individual genetically identical trees of the genus Populus can also be exposed to contrasting environmental conditions by being grown in different locations. As such, clonally propagated Populus trees provide an opportunity to interrogate the impact of individual environmental history on current response to environmental stimuli. To test the hypothesis that current responses to an environmental stimulus, drought, are contingent on environmental history, the transcriptome- level drought responses of three economically important hybrid genotypes—DN34 (Populus deltoides × Populus nigra), Walker [P. deltoides var. occidentalis × (Populus laurifolia × P. nigra)], and Okanese [Walker × (P. laurifolia × P. nigra)]—derived from two different locations were compared. Strikingly, differences in transcript abundance patterns in response to drought were based on differences in geographic origin of clones for two of the three genotypes. This observation was most pronounced for the genotypes with the longest time since establishment and last common propagation. Differences in genome-wide DNA methylation paralleled the transcriptome level trends, whereby the clones with the most divergent transcriptomes and clone history had the most marked differences in the extent of total DNA methylation, suggesting an epigenomic basis for the clone history-dependent transcriptome divergence. The data provide insights into the interplay between genotype and environment in the ecologically and economically important Populus genus, with implications for the industrial application of Populus trees and the evolution and persistence of these important tree species and their associated hybrids. PMID:21746919

  4. Effects of preparation process on performance of rubber modified asphalt

    NASA Astrophysics Data System (ADS)

    Liu, Hanbing; Luo, Guobao; Wang, Xianqiang; Jiao, Yubo

    2015-06-01

    The rational utilization of waste rubber tire is essential for the environmental protection. Utilizing rubber particles to modify asphalt can not only improve asphalt performance, but also help the recycling of waste materials. Considering the effect of different preparation process parameters on the performance of rubber modified asphalt, this paper analyzes the effects of the shear temperature, shear time and shear rate on the performance of rubber modified asphalt, and provided a reference for its preparation.

  5. Estimating the Degree of Cross-Linking in Rubber

    NASA Technical Reports Server (NTRS)

    Fedors, R. F.

    1983-01-01

    Degree of cross-linking or network chain concentration of rubber estimated with aid of new method. Quantity is needed in studies of mechanical behavior of rubber. New method is based on finding rubber follows different stress/ strain relationships in extension and retraction. When rubber specimen is stretched to given extension ration and released. Stress-vs-strain curve follows two paths: one for extension and other for retraction.

  6. Use of scrap rubber in asphalt pavement surfaces. Special report

    SciTech Connect

    Eaton, R.A.; Roberts, R.J.; Blackburn, R.R.

    1991-12-01

    Scrap tire rubber was mixed into an asphalt concrete wearing course to study the effect of ice disbonding from the pavement surface under traffic. Rubber contents of 0, 3, 6, and 12% by weight were studied. Initial laboratory ice disbonding test results led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.

  7. Evaluation of Asphalt Rubber Binders in Porous Friction Courses

    DTIC Science & Technology

    1992-05-01

    5RE, AC-5R, and AC-20R for all tests in this study. The crumb rubber used in each asphalt rubber blend was made of 100 percent reclaimed waste tires ...binder’s tendency to age harden at the asphalt plant . The exception to this statement may be when an extender oil is added with the crumb rubber such as...equipment ......................... 40 21 Crumb rubber after milling .......................................... 43 22 Absolute viscosity test results

  8. Quick and clean cloning.

    PubMed

    Thieme, Frank; Marillonnet, Sylvestre

    2014-01-01

    Identification of unknown sequences that flank known sequences of interest requires PCR amplification of DNA fragments that contain the junction between the known and unknown flanking sequences. Since amplified products often contain a mixture of specific and nonspecific products, the quick and clean (QC) cloning procedure was developed to clone specific products only. QC cloning is a ligation-independent cloning procedure that relies on the exonuclease activity of T4 DNA polymerase to generate single-stranded extensions at the ends of the vector and insert. A specific feature of QC cloning is the use of vectors that contain a sequence called catching sequence that allows cloning specific products only. QC cloning is performed by a one-pot incubation of insert and vector in the presence of T4 DNA polymerase at room temperature for 10 min followed by direct transformation of the incubation mix in chemo-competent Escherichia coli cells.

  9. Anaerobic desulfurization of ground rubber with the thermophilic archaeon Pyrococcus furiosus--a new method for rubber recycling.

    PubMed

    Bredberg, K; Persson, J; Christiansson, M; Stenberg, B; Holst, O

    2001-01-01

    The anaerobic sulfur-reducing archaeon Pyrococcus furiosus was investigated regarding its capacity to desulfurize rubber material. The microorganism's sensitivity towards common rubber elastomers and additives was tested and several were shown to be toxic to P. furiosus. The microorganism was shown to utilize sulfur in vulcanized natural rubber and an increase in cell density was obtained when cultivated in the presence of spent tire rubber. Ethanol-leached cryo-ground tire rubber treated with P. furiosus for 10 days was vulcanized together with virgin rubber material (15% w/w) and the mechanical properties of the resulting material were determined. The increase in the stress at break value and the decrease in swell ratio and stress relaxation rate obtained for material containing microbially treated rubber (compared to untreated material) show the positive effects of microbial desulfurization on rubber.

  10. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b)...

  11. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  12. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  13. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b)...

  14. Bonding soft rubber or plasticized elastomers to metal

    NASA Technical Reports Server (NTRS)

    Clemons, J. M.; Ledbetter, F. E., III; White, W. T.

    1980-01-01

    Approach using bond-cover coat of unplasticized rubber between soft rubber and adhesive eliminates diffusion problem. Approach is useful in making improved seals in automobile engines, industrial and public plumbing, and in other areas using soft-rubber-to-metal bonds. Seals and gaskets made this way would not have to be replaced very often, reducing cost of maintenance.

  15. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  16. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  17. Modified Silicone-Rubber Tooling For Molding Composite Parts

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Snoha, John J.; Weiser, Erik S.

    1995-01-01

    Reduced-thermal-expansion, reduced-bulk-modulus silicone rubber for use in mold tooling made by incorporating silica powder into silicone rubber. Pressure exerted by thermal expansion reduced even further by allowing air bubbles to remain in silicone rubber instead of deaerating it. Bubbles reduce bulk modulus of material.

  18. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b)...

  19. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b)...

  20. 30 CFR 77.606-1 - Rubber gloves; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b)...

  1. 21 CFR 872.6300 - Rubber dam and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rubber dam and accessories. 872.6300 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in...

  2. A sustainability review of domestic rubber from the guayule plant

    USDA-ARS?s Scientific Manuscript database

    Guayule (Parthenium argentatum Gray) is an arid-adapted, low-input perennial shrub native to Mexico and southern Texas that has received considerable attention as an alternative source of natural rubber. It has potential to replace the most common types of rubbers, including synthetic rubber derived...

  3. Interface interactions of natural rubber and protein/fiber aggregates

    USDA-ARS?s Scientific Manuscript database

    Mechanical properties of natural rubber are improved with a renewable filler for rubber applications. Aggregates of protein and fiber that constitute soy protein concentrate were shear-reduced and used to enhance the tensile modulus of the natural rubber. The aqueous dispersion of the shear-reduced ...

  4. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  5. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  6. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  7. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  8. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  9. Development of crops to produce industrially useful natural rubber

    USDA-ARS?s Scientific Manuscript database

    Natural rubber, cis-1,4-polyisoprene, is an essential industrial commodity that most developed countries have to import. Hevea brasiliensis (Hevea), grown in tropical and subtropical areas is the primary source of natural rubber. The high quality and quantity of the rubber cause us to focus on und...

  10. Immediate reactions to rubber products.

    PubMed

    Fuchs, T; Wahl, R

    1992-01-01

    There is an increasing incidence of contact urticaria (CU) and systemic reactions to rubber products. Thirty-one patients are presented: most were atopic (20/31) and women (26/31); 71% worked in the medical field; 32.2% (10/31) showed signs of hand dermatitis. In 28 patients (90.3%), rub and/or prick tests with liquid latex in different dilutions and with latex gloves led to an immediate type of positive reaction. The allergen(s) appear in part to be water soluble: 20 of 28 patients (71.4%) revealed positive test reactions to an aqueous glove extract. In two patients, urticarial test reactions to tetramethylthiuram disulfide (TMTD), mercapto mix, and p-phenylenediamine (PPD mix) were considered as possible contributing factors of CU. Cornstarch was negative in all patients (scratch). Sixteen of 27 sera (59.2%) showed radioallergosorbent (RAST) class 0 using latex allergen disks. Sodium dodecyl sulfate-polyacoyl-amide (SDS-PAGE) determined protein bands of less than or equal to 14 kD (not allergen specific) and approx 28 kD. The Western blot detected the 28 kD protein as allergen in the sera of three patients. Isoelectric focusing (IEF) proved no protein bands. Immunoprinting performed with sera of five patients presented allergen bands in a pH range between 3.8 and 4.55. This shows the radio staining (immunoprint) is more sensitive than is the Coomassie blue staining. Although three sera showed RAST class 0, immunoblotting detected allergen bands. In this case the immunoblot appears to be more sensitive than the RAST. A cross reactivity between latex and banana could not be established. Alternative gloves are Neolon (neoprene) or Elastyren (styrene-butadiene polymer).

  11. Vulcanization and the mechanical response of rubber

    NASA Astrophysics Data System (ADS)

    Kundurthi, S.; Mythravaruni, P.; Ravindran, P.

    2015-06-01

    Hyperelastic models are widely used to describe the mechanical response of rubber. However, purely mechanical models cannot account for changes in the material due to chemical reactions such as those that take place during vulcanization. Here, we present a model developed within a thermodynamic framework accounting for chemical reactions. A mixture theory approach that allows for the existence of multiple species and their interconversion is followed. The existence of a Helmholtz potential and a rate of entropy production function for the mixture as a whole are posited. Following the multiple natural configuration approach, the rate of entropy production is maximized to obtain constitutive equations. The viscoelastic model is then specialized to the elastic case. The model is calibrated using data available in the literature for rubber. A simulation of the stress-strain curve of rubber as vulcanization progresses is presented.

  12. Coatings for rubber bonding and paint adhesion

    NASA Astrophysics Data System (ADS)

    Boulos, M. S.; Petschel, M.

    1997-08-01

    Conversion coatings form an important base for the adhesion of paint to metal substrates and for the bonding of rubber to metal parts. Four types of conversion coatings were assessed as base treatments for the bonding of rubber to steel and for the corrosion protection of metal substrates under paint: amorphous iron phosphate, heavy zinc phosphate, and three types of modified zinc phosphates that utilized one or more metal cations in addition to zinc. When applied, these conversion coatings formed a thin film over the metal substrate that was characterized by scanning electron microscopy, x-ray diffraction, and chemical methods. The performance of the coatings was assessed using physical methods such as dry adhesion, conical mandrel, impact, and stress adhesion for the rubber-bonded parts, and by corrosion resistance methods such as humidity, salt spray, and cyclic corrosion. Coating characterization and performance were correlated.

  13. Oxygen exchange in silicone rubber capillaries.

    PubMed

    Heineken, F G; Predecki, P K; Filley, G F

    1978-06-01

    Capillaries of 7 and 12.5 mu diameter have been fabricated in silicone rubber. Whole blood treated with heparin has been perfused through these capillaries. Under flowing conditions, no clotting or other clumping effects have been observed and red cells appear to maintain a constant velocity. Oxygen transfer data to and from saline perfusing the 12.5 mu diameter capillaries have been obtained in order to determine how rapidly O2 will permeate the silicone rubber film. The data indicate that the capillaries simulate lung tissue oxygen exchange and will allow for the first time the experimental determination of oxygen exchange kinetics in flowing whole blood.

  14. The role of the small rubber particle protein in determining rubber yields and polymer length in Russian dandelion

    USDA-ARS?s Scientific Manuscript database

    Several proteins have been identified and implicated in natural rubber biosynthesis, one of which, the small rubber particle protein (SRPP), was originally identified in Hevea brasiliensis as an abundant protein associated with cytosolic vesicles known as rubber particles. While previous in vitro s...

  15. Kinetics of zinc release from ground tire rubber and rubber ash in a calcareous soil as alternatives to Zn fertilizers

    USDA-ARS?s Scientific Manuscript database

    Ground rubber contains 15-20 g Zn/kg but very low levels of Cd and could serve as an inexpensive byproduct Zn fertilizer. The aim of this investigation was to test the kinetics of Zn release in a soil treated with ground tire rubber and rubber ash compared with commercial Zn fertilizer and a labora...

  16. Evapotranspiration of rubber (Hevea brasiliensis) under the highly seasonal rainfall regime of the Asian monsoon in mainland Southeast Asia

    NASA Astrophysics Data System (ADS)

    Giambelluca, T. W.; Mudd, R. G.; Liu, W.; Kobayashi, N.; Ziegler, A. D.; Miyazawa, Y.; Kumagai, T.; Huang, M.

    2012-12-01

    The Asian Monsoon dominates the climate of the mainland Southeast Asia (MSEA) region, characterized by a highly seasonal rainfall regime in which 80-90% of annual rainfall occurs during the 6-month (May-October) wet season. The accompanying extremes in soil moisture, solar radiation, and vapor pressure deficit exert strong controls on ecosystem fluxes, including evapotranspiration (ET). Rubber (Hevea brasiliensis), the major commercial crop currently replacing traditional agriculture and secondary forests in MSEA is a native of the equatorial Amazon rainforest, and differs physiologically from the dominant native SE Asian forest tree species. It sheds its leaves in the middle of the dry season and flushes new leaves before the onset of the wet season. In some areas, rubber cultivation is suspected of having caused changes in local climate and watershed processes, including a dramatic downward trend in fog frequency and large increases in surface runoff and soil erosion (Wu et al., 2001, Int. J. Sust. Dev. World Ecol. 8:337-345). Guardiola-Claramonte et al. (2008, Ecohydrology 1:13-22; 2010, Ecohydrology 3:306-314) noted striking differences in the timing and rate of dry season root-water extraction under rubber as compared with other vegetation types. To investigate the environmental impacts of rubber, eddy covariance flux towers were installed to monitor energy, water, and carbon exchange at rubber plantation sites in northeastern Thailand and Cambodia. Results of the first two years of observations at the sites indicate that controls on ET differ between wet and dry seasons, with varying responses to energy, soil moisture, canopy wetness, and leaf area. Despite the long dry season and loss of leaves for several weeks, rubber accumulates exceptionally high annual ET totals, exceeding those of natural forest and other plant functional types in the region. The phenology of rubber represents a disruption of the land-atmosphere interactions of native and other non-rubber

  17. Criteria for Asphalt-Rubber Concrete in Civil Airport Pavements: Mixture Design.

    DTIC Science & Technology

    1986-07-01

    8217s. These early experiments included the introduction of various forms of rubber (including latex, devulcanized or reclaimed rubber, raw and ground...addition to rubber morphology, the size of the rubber particles and whether the rubber has been processed after grinding, i.e., devulcanized , both...Method B. Method A uses ground reclaimed " devulcanized " rubber and an extender oil whereas Method B uses ground reclaimed vulcanized rubber and a kerosene

  18. Radiation-induced vulcanisation of natural rubber latex in presence of styrene-butadiene rubber latex

    NASA Astrophysics Data System (ADS)

    Chaudhari, C. V.; Bhardwaj, Y. K.; Patil, N. D.; Dubey, K. A.; Kumar, Virendra; Sabharwal, S.

    2005-04-01

    Radiation vulcanisation of natural rubber latex in presence of styrene butadiene rubber latex (SBRL) has been investigated. The cast films were characterised for their swelling properties, tensile strength and thermal stability as a function of radiation dose as well as SBRL content. The gel content, tensile strength and thermal stability of the copolymer films were found to increase with increasing the SBRL content in the feed solution and radiation dose.

  19. Enzymatic synthesis of rubber polymer in Hevea brasiliensis

    SciTech Connect

    Tang, F.; Hu, S.; Benedict, C.R. )

    1991-05-01

    Light and Dennis purified serum soluble rubber transferase from Hevea latex to homogeneity. Prenyl transferase co-purified with rubber transferase. In the absence of washed rubber particles (WRP) the prenyl transferase catalyzed the formation of trans FPP from DMAPP and IPP. In the presence of WRP the transferase catalyzed cis additions of IPP to pre-existing rubber chains. Control mixtures of WRP, Mg{sup 2+} and FPP were not included to test for the contributions of the bound rubber transferase on WRP to the incorporation of IPP into polyisoprene. Bound rubber transferase catalyzes the repetitive addition of IPP to allylic-PP starter molecules to form polyisoprene. The order of utilization of allylic-PP starters was GGPP > FPP > GPP > DMAPP. The authors have shown that the polyisoprene enzymatically synthesized on WRP is a bimodal polymer consisting of different mol wt rubber chains similar to the polymeric characteristics of natural rubber. The bound rubber transferase was solubilized with Chaps and purified on DEAE-cellulose. The polymerization reaction catalyzed by the purified preparation showed a 98% requirement for pre-existing rubber chains. Results suggest that the prenyl transferase from Hevea serum may be part of the polymer starter system furnishing allylic-PP for the bound rubber transferase.

  20. The use of rubber dam among Czech dental practitioners.

    PubMed

    Kapitán, Martin; Sustová, Zdenka

    2011-01-01

    Rubber dam is considered an ideal device for tooth isolation. Nevertheless, its usage is quite rare in the Czech Republic. The aim of this study was: firstly, to gather and evaluate information regarding the use of rubber dam by dentists in the Czech Republic and to compare it with other countries; secondly to find out whether there are any influencing factors as to rubber dam usage; and finally to find out frequency of rubber dam use separately in endodontic treatment and in placing fillings of different materials. A questionnaire-based survey was conducted. Dentists filled in the questionnaires during dental conventions, educational events, conferences and congresses. Rubber dam was routinely used by less than eight per cent of the respondents (n = 35); less than twenty-two per cent of the respondents (n = 97) used rubber dam occasionally, and more than seventy per cent of the respondents (n = 317) has never use it. The results showed that rubber dam is not used frequently in the Czech Republic. If rubber dam is used, then it is typically for endodontic treatment or composite fillings. There were several factors with a statistically significant influence on the usage of rubber dam, such as gender, length of professional career, percentage of direct payments, previous experience in using rubber dam, and undergraduate training in rubber dam use.

  1. Thermal cracking of rubber modified pavements, May 1995. Final report

    SciTech Connect

    Raad, L.; Yuan, X.; Saboundjian, S.

    1995-05-01

    In accordance with the original ISTEA mandate (1991) to use crumb tire rubber in pavements, Alaska would be required to use about 250 tons of used tire rubber starting in 1994 and increasing to about 1,000 tons of rubber in 1997 and each year thereafter. A number of pavements using crumb rubber modifiers have been built in the state and have been in service for periods of 8 to 15 years. Knowledge of the behavior of these rubber-modified pavements under extreme climate conditions, particularly in relation to their low temperature cracking resistance, is necessary for future design and construction of rubberized pavements in Alaska. This report presents results of a study to determine the low temperature cracking resistance of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements.

  2. Microlenses Fabricated on Silicone Rubber Using F2 Laser

    NASA Astrophysics Data System (ADS)

    Takao, Hiromitsu; Miyagami, Hideyuki; Okoshi, Masayuki; Inoue, Narumi

    2005-04-01

    Microlenses are fabricated on silicone rubber surfaces employing phenomena in which silicone rubber swells and is modified to SiO2 by F2 laser irradiation at a laser fluence lower than the ablation threshold. In this method, silicone rubber is irradiated using a F2 laser beam through a mask which has circular apertures 10, 20, and 25 μm in diameter. Since silicone rubber swells by laser irradiation, it is necessary to separate the mask from the silicone rubber surface. The swelling is spherical and its surface becomes smooth when the distance between the mask and the silicone rubber surface is very small. The focal lengths of the microlenses are 10-170 μm, which are controlled by adjusting the number of irradiated pulses. Additionally, a 790 nm femtosecond laser beam is focused by the fabricated microlenses, and enables the microdrilling of fluorinated rubber.

  3. Hardness and compression resistance of natural rubber and synthetic rubber mixtures

    NASA Astrophysics Data System (ADS)

    Arguello, J. M.; Santos, A.

    2016-02-01

    This project aims to mechanically characterize through compression resistance and shore hardness tests, the mixture of hevea brasiliensis natural rubber with butadiene synthetic rubber (BR), styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer rubber (EPDM). For each of the studied mixtures were performed 10 tests, each of which increased by 10% the content of synthetic rubber in the mixture; each test consisted of carrying out five tests of compression resistance and five tests of shore hardness. The specimens were vulcanized on a temperature of 160°C, during an approximate time of 15 minutes, and the equipment used in the performance of the mechanical tests were a Shimadzu universal machine and a digital durometer. The results show that the A shore hardness increases directly proportional, with a linear trend, with the content of synthetic BR, SBR or EPDM rubber present in the mixture, being the EPDM the most influential. With respect to the compression resistance is observed that the content of BR or SBR increase this property directly proportional through a linear trend; while the EPDM content also increases but with a polynomial trend.

  4. Carboxy terminated rubber based on natural rubber grafted with acid anhydrides and its adhesion properties

    NASA Astrophysics Data System (ADS)

    Klinpituksa, P.; Kongkalai, P.; Kaesaman, A.

    2014-08-01

    The chemical modification of natural rubber by grafting of various polar functional molecules is an essential method, improving the versatility of rubber in applications. This research investigated the preparation of natural rubber-graft-citraconic anhydride (NR-g-CCA), natural rubber-graft-itaconic anhydride (NR-g-ICA), and natural rubber-graft-maleic anhydride (NR-g-MA), with the anhydrides grafted to natural rubber in toluene using benzoyl peroxide as an initiator. Variations of monomer content, initiator content, temperature and reaction time of the grafting copolymerization were investigated. The maximum degrees of grafting were 1.06% for NR-g-CCA, 4.66% for NR-g-ICA, and 5.03% for NR-g-MA, reached using 10 phr citraconic anhydride, 10 phr of itaconic anhydride, or 8 phr of maleic anhydride, 3 phr benzoyl peroxide, at 85, 80 and 80°C for 2, 2 and 3 hrs, respectively. Solvent-based wood adhesives were formulated from these copolymers with various contents of wood resin in the range 10-40 phr. The maximal 289 N/in cleavage peel and 245.7 KPa shear strength for NR-g-MA (5.03% grafting) were obtained at 40 phr wood resin.

  5. Preparation of sulfonic acid-containing rubbers from natural rubber vulcanizates

    NASA Astrophysics Data System (ADS)

    Poonsawat, Worapong; Poompradub, Sirilux; Ngamcharussrivichai, Chawalit

    2014-06-01

    In this work, a series of sulfonic acid-containing rubbers were prepared by aqueous phase oxidation of natural rubber vulcanizates in the presence of hydrogen peroxide (H2O2) and formic acid (HCOOH). The starting vulcanizates were neatly prepared via an efficient vulcanization (EV) system by varying mass ratio of N-cyclohexyl-2-benzothiazole sulfonamide (CBS), as an accelerator, to sulfur. The oxidation conditions were controlled at the molar ratio of H2O2: HCOOH = 1:1, the concentration of H2O2 = 15 wt.%, the temperature = 50 °C, and the reaction time = 3 h. The rubber materials before and after the oxidation were characterized for their physicochemical properties by using Fourier transform infrared spectroscopy, bomb calorimetry, acid-base titration and swelling measurements. The results indicated the presence of sulfonic acid group in the oxidized rubbers, generated by the oxidative cleaves of sulfide crosslinks in the rubber vulcanizates. The oxidation decreased the sulfur content of the rubber in which the level of sulfur loss was determined by the CBS/sulfur ratio. Moreover, the acidity of the oxidized products was correlated with the amount of sulfur remaining.

  6. Fundamental Study on Self-healing Insulation Performance of Silicone Rubber Affected by Local Breakdown

    NASA Astrophysics Data System (ADS)

    Hozumi, Naohiro; Nishioka, Koji; Suematsu, Takeshi; Murakami, Yoshinobu; Nagao, Masayuki; Sakata, Hiroshi

    Feasibility of self-healing insulation system was studied. A silicone rubber without filler was mounted on a glass substrate with a needle electrode. An ac voltage with 4 kV in rms was applied. The voltage was cut off when the tree had propagated into 150 micrometers in length. After the cut-off, the partial discharge inception voltage was periodically observed. The partial discharge inception voltage had once reduced into as low as 2 kV. However, it gradually increased with time, and finally exceeded the tree inception voltage (4 kV) when 30 - 60 hours had passed. It was also observed by optical microscope that the tree gradually disappeared in parallel with the recovery of the partial discharge inception voltage. The same phenomenon was observed even if 1 kV ac voltage had been continuously applied during the process of the recovery. A simulation using a needle-shaped void was performed in order to clarify the mechanism of the self-healing effect. It was observed that the tip of the needle-shaped void gradually got wet with a liquid material. It would be the result of "bleed-out" of the low molecular component included in the rubber. The tip of the void was finally filled with the liquid, however, the rest of the needle-shaped void stayed without being filled. In this type of tree, it was suggested that the self-healing effect is expected if the diameter of the tree did not exceed ca. 5 micrometers.

  7. Network cloning unfolds the effect of clustering on dynamical processes

    NASA Astrophysics Data System (ADS)

    Faqeeh, Ali; Melnik, Sergey; Gleeson, James P.

    2015-05-01

    We introduce network L -cloning, a technique for creating ensembles of random networks from any given real-world or artificial network. Each member of the ensemble is an L -cloned network constructed from L copies of the original network. The degree distribution of an L -cloned network and, more importantly, the degree-degree correlation between and beyond nearest neighbors are identical to those of the original network. The density of triangles in an L -cloned network, and hence its clustering coefficient, is reduced by a factor of L compared to those of the original network. Furthermore, the density of loops of any fixed length approaches zero for sufficiently large values of L . Other variants of L -cloning allow us to keep intact the short loops of certain lengths. As an application, we employ these network cloning methods to investigate the effect of short loops on dynamical processes running on networks and to inspect the accuracy of corresponding tree-based theories. We demonstrate that dynamics on L -cloned networks (with sufficiently large L ) are accurately described by the so-called adjacency tree-based theories, examples of which include the message passing technique, some pair approximation methods, and the belief propagation algorithm used respectively to study bond percolation, SI epidemics, and the Ising model.

  8. Chemical changes in rubber allergens during vulcanization.

    PubMed

    Bergendorff, Ola; Persson, Christina; Lüdtke, Anna; Hansson, Christer

    2007-09-01

    Allergic contact dermatitis to rubber is caused by residues of chemicals used in manufacturing a rubber product. Several different additives are used to achieve a final product of the desired characteristics. Accelerators such as thiurams, dithiocarbamates, and mercaptobenzothiazoles are often among the additives responsible for allergic reactions recognized by dermatologists. The chemistry of the vulcanization process is complicated; as it occurs at an elevated temperature with a mixture of reactive chemicals, the compositions of the initial and final products differ. This paper investigates the changes in composition of common allergens during vulcanization, doing so by chemically analysing various rubber formulations at different stages of the process. Major changes were found in which added chemicals were consumed and new ones produced. An important observation is that thiuram disulfides rarely appear in the final rubber although they may have been used as additives. Instead, thiurams are often converted to dithiocarbamates or to products formed by addition to mercaptobenzothiazole structures, if these have been used together with thiurams as accelerators.

  9. Beta Backscatter Measures the Hardness of Rubber

    NASA Technical Reports Server (NTRS)

    Morrissey, E. T.; Roje, F. N.

    1986-01-01

    Nondestructive testing method determines hardness, on Shore scale, of room-temperature-vulcanizing silicone rubber. Measures backscattered beta particles; backscattered radiation count directly proportional to Shore hardness. Test set calibrated with specimen, Shore hardness known from mechanical durometer test. Specimen of unknown hardness tested, and radiation count recorded. Count compared with known sample to find Shore hardness of unknown.

  10. Why Do Calculators Have Rubber Feet?

    ERIC Educational Resources Information Center

    Heavers, Richard M.

    2007-01-01

    Our students like using the covers of their TI graphing calculators in an inquiry-based extension of a traditional exercise that challenges their preconceived ideas about friction. Biology major Fiona McGraw (Fig. 1) is obviously excited about the large coefficient of static friction ([mu][subscript s] = 1.3) for the four little rubber feet on her…

  11. Rubber valve seal with tough skin

    NASA Technical Reports Server (NTRS)

    Martin, J. W.

    1979-01-01

    Curing technique for producing variable viscosity seal has hard sealing surface supported by softer rubber. Valve seal is clamped between two jaws for curing with hotter jaw at temperature of approximately 350 F and lower at room temperature. Result is durable tight valve-seat.

  12. Reinforcement of graphene in natural rubber nanocomposite

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Kamal, M. M.; Rusop, M.

    2016-07-01

    In the present work, we report the use of graphene as multi-functional nanofiller for natural rubber (NR). Dispersion of reduced graphene into natural rubber (NR) was found to enhance the mechanical and electrical properties of NR. Through a facile approach rubber molecules are successfully grafted onto the surface of graphene. Stable graphene suspension with NR afforded a weblike morphology consisting of platelet networks between the rubber particles, while internal mixer processing broke down this structure, yielding a homogeneous and improved dispersion. The resulting graphene can be dispersed in NR via dry mixing. It is found that graphene is prominent in improving the mechanical properties of NR at low filler loading. The percolation point of graphene in the nanocomposites takes place at a content of less than 0.1 wt%. With incorporation of as low as 0.1 wt% of graphene, an increase in the tensile strength and improvement in the tensile modulus achieved. The improvement in the mechanical properties of NR nanocomposites at such low filler loading is attributed to the strong interfacial interaction and the molecular-level dispersion of graphene in the NR matrix. .

  13. Microbial Degradation of Natural Rubber Vulcanizates

    PubMed Central

    Tsuchii, Akio; Suzuki, Tomoo; Takeda, Kiyoshi

    1985-01-01

    An actinomycete, Nocardia sp. strain 835A, grows well on unvulcanized natural rubber and synthetic isoprene rubber, but not on other types of synthetic rubber. Not only unvulcanized but also various kinds of vulcanized natural rubber products were more or less utilized by the organism as the sole source of carbon and energy. The thin film from a latex glove was rapidly degraded, and the weight loss reached 75% after a 2-week cultivation period. Oligomers with molecular weights from 104 to 103 were accumulated during microbial growth on the latex glove. The partially purified oligomers were examined by infrared and 1H nuclear magnetic resonance and 13C nuclear magnetic resonance spectroscopy, and the spectra were those expected of cis-1, 4-polyisoprene with the structure, OHC—CH2—[—CH2—C(—CH3)=CH —CH2—]n—CH2—C(=O)— CH3, with average values of n of about 114 and 19 for the two oligomers. PMID:16346923

  14. Why Do Calculators Have Rubber Feet?

    ERIC Educational Resources Information Center

    Heavers, Richard M.

    2007-01-01

    Our students like using the covers of their TI graphing calculators in an inquiry-based extension of a traditional exercise that challenges their preconceived ideas about friction. Biology major Fiona McGraw (Fig. 1) is obviously excited about the large coefficient of static friction ([mu][subscript s] = 1.3) for the four little rubber feet on her…

  15. Double Jeopardy: The Rubber Ball Bounces Twice.

    PubMed

    Arbiser, Jack L; Gilbert, Linda C

    2017-01-01

    Soblet et al. describe cis mutations in TEK/Tie-2 in blue rubber bleb nevus and sporadic vascular malformations. This suggests that the remaining normal allele is required for the phenotype. Second, it suggests therapeutic approaches to treatment signal transduction inhibition.

  16. Identification and Waste Reduction on Rubber Industry

    NASA Astrophysics Data System (ADS)

    Syahputri, K.; Sari, R. M.; Rizkya, I.; Siregar, I.

    2017-03-01

    Lots of activities in production process can be lead to waste activities. The waste may cause a degree of efficiency of an industry to be low. This research was conducted in the rubber industry. In the rubber industry has been a decline in the level of efficiency. Decreased levels of efficiency occurs because many inefficient activities that take place during the production process. Activities that were not contributed to the value of the product lead to waste during the production process. Identification by the activity is a way to minimize the waste that occurs so that the efficiency of the production process can be improved. Process activity mapping in the rubber industry used to identify the activities that take place on the floor of production in order to reduce waste and propose improvements that can be done to improve efficiency. The total waste that occurs in crumb rubber industry amounted to 94 minutes or 1.56 hours. For the proposed improvements in order to reduce waste are based on two activities, such as transport and unnecessary motion. Transport activities proposed use of material handling in their daily activities and to unnecessary motion by doing a variety of work on the operator.

  17. Wettability of silicone rubber maxillofacial prosthetic materials.

    PubMed

    Waters, M G; Jagger, R G; Polyzois, G L

    1999-04-01

    Maxillofacial prosthetic materials that contact skin or mucosa should have good wettability. A material that is easily wetted will form a superior lubricating layer between the supporting tissues and, thus, reduce friction and patient discomfort. The surface energy of a maxillofacial prosthetic material will give an indication of the amount of energy available for adhesion and of the susceptibility of the material to bacterial adhesion. This study evaluated the wettability and surface energies of a range of commercially available silicone rubber maxillofacial prosthetic materials. Contact angles and surface energies were measured by using a dynamic contact angle measuring technique. Four commonly used silicone maxillofacial materials were tested and their properties compared with those of an acrylic resin denture base material and a widely used denture soft lining material. There were no significant differences in the wettability of the silicone rubber materials. All materials were significantly less wetted than the denture acrylic resin material. There were no significant differences in the surface energies of the silicone rubber materials, but all were significantly lower than denture acrylic resin material. The Cahn dynamic contact angle analyzer was a quick and reproducible method for determining the contact angles and surface energies of maxillofacial materials. Further work is needed to improve the wettability of silicone rubber materials used for maxillofacial prostheses, thus, reducing their potential to produce friction with tissues.

  18. Beta Backscatter Measures the Hardness of Rubber

    NASA Technical Reports Server (NTRS)

    Morrissey, E. T.; Roje, F. N.

    1986-01-01

    Nondestructive testing method determines hardness, on Shore scale, of room-temperature-vulcanizing silicone rubber. Measures backscattered beta particles; backscattered radiation count directly proportional to Shore hardness. Test set calibrated with specimen, Shore hardness known from mechanical durometer test. Specimen of unknown hardness tested, and radiation count recorded. Count compared with known sample to find Shore hardness of unknown.

  19. Rubber Impact on 3D Textile Composites

    NASA Astrophysics Data System (ADS)

    Heimbs, Sebastian; Van Den Broucke, Björn; Duplessis Kergomard, Yann; Dau, Frederic; Malherbe, Benoit

    2012-06-01

    A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools.

  20. Boron-Loaded Silicone Rubber Scintillators

    SciTech Connect

    Bell, Z.W.; Maya, L.; Brown, G.M.; Sloop, F.V.Jr

    2003-05-12

    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon response were obtained, and although the light output was found to be much poorer than from samples in which boron was dissolved, the higher boron concentrations enabled essentially 100% neutron absorption in only a few millimeters' thickness of rubber.

  1. Nuclear transfer and cloning.

    PubMed

    Wolf, D P

    2001-10-01

    The use of nuclear transfer in human reproductive and therapeutic cloning is reviewed with attention on the origins of this technology from its evolution to the present. The successes and limitations of mammalian reproductive cloning are itemized. A case is made against the use of human reproductive cloning to reproduce an existing person, based on the unacceptable risks to the embryo, fetus, or newborn. However, support is extended for human therapeutic cloning involving the derivation and use of embryonic stem cells to treat human disease.

  2. [Cloning--ethical aspects].

    PubMed

    Munzarová, M

    2004-01-01

    Ethical problems related to cloning are discussed on three model situations: cloning of human beings (for example by utilizing the techniques of embryo splitting or nuclear transfer), use of embryonic cells in cloning techniques and cloning of nonembryonic cells. The first situation is strictly condemned, the second has been examined up present (it should be condemned as well) and the third is--under certain conditions--fully acceptable. The issue is discussed from the point of view of relevant Council of Europe documents as well.

  3. Similarities and differences in rubber biochemistry among plant species.

    PubMed

    Cornish, K

    2001-08-01

    This report reviews aspects of the biochemical regulation of rubber yield and rubber quality in three contrasting rubber-producing species, Hevea brasiliensis, Parthenium argentatum and Ficus elastica. Although many similarities are revealed, considerable differences also exist in enzymatic mechanisms regulating biosynthetic rate and the molecular weight of the rubber biopolymers produced. In all three species, rubber molecule initiation, biosynthetic rate and molecular weight, in vitro, are dependent upon substrate concentration and the ratio of isopentenyl pyrophosphate (IPP, the elongation substrate, or monomer) and farnesyl pyrophosphate (FPP, an initiator), but these parameters are affected by intrinsic properties of the rubber transferases as well. All three rubber transferases are capable of producing a wide range of rubber molecular weight, depending upon substrate concentration, clearly demonstrating that the transferases are not the prime determinants of product size in vivo. However, despite these commonalities, considerable differences exist between the species with respect to cosubstrate effects, binding constants, effective concentration ranges, and the role of negative cooperativity in vitro. The P. argentatum rubber transferase appears to exert more control over the molecular weight it produces than the other two species and may, therefore, provide the best prospect for the source of genes for transformation of annual crop species. The kinetic data, from the three contrasting rubber-producing species, also were used to develop a model of the rubber transferase active site in which, in addition to separate IPP and allylic-PP binding sites, there exists a hydrophobic region that interacts with the linear portion of allylic-PP initiator proximal to the pyrophosphate. Substrate affinity increases until the active site is traversed and the rubber interior of the rubber particle is reached. The kinetic data suggest that the hydrophobic region in H

  4. Cancer mortality and morbidity among rubber workers.

    PubMed

    Monson, R R; Fine, L J

    1978-10-01

    Mortality and morbidity from cancer among a cohort of 13,570 white male rubber workers were examined. Each man worked for at least 5 years at the Akron, Ohio, plant of the B. F. Goodrich Company. The potential period of follow-up was from January 1, 1940 to June 30, 1976. Departmental work histories were based primarily on records maintained by Local no. 5, United Rubber Workers. The occurrence of cancer was measured by death certificates and by a survey of Akron-area hospital tumor registries from 1964 to 1974. Two types of analyses were made: 1) an external comparison of mortality rates of rubber workers versus rates of U.S. white males, and 2) an internal comparison of cancer morbidity rates among persons who were employed in various work areas of the plant. Excess cases of specific cancers (observed/expected numbers) among workers in specific work areas included: stomach and intestine: rubber making (30/14.4); lung: tire curing (31/14.1), fuel cells and/or deicers (46/29.1); bladder: chemical plant (6/2.4), and tire building (16/10.7); skin cancer: tire assembly (12/1.9); brain cancer: tire assembly (8/2.0); lymphatic cancer: tire building (8/3.2); and leukemia: calendering (8/2.2), tire curing (8/2.6), tire building (12/7.5), elevators (4/1.4), tubes (4/1.6), and rubber fabrics (4/1.1). Agents that may be responsible for these excesses were considered.

  5. Audubon Tree Study Program.

    ERIC Educational Resources Information Center

    National Audubon Society, New York, NY.

    Included are an illustrated student reader, "The Story of Trees," a leaders' guide, and a large tree chart with 37 colored pictures. The student reader reviews several aspects of trees: a definition of a tree; where and how trees grow; flowers, pollination and seed production; how trees make their food; how to recognize trees; seasonal changes;…

  6. Audubon Tree Study Program.

    ERIC Educational Resources Information Center

    National Audubon Society, New York, NY.

    Included are an illustrated student reader, "The Story of Trees," a leaders' guide, and a large tree chart with 37 colored pictures. The student reader reviews several aspects of trees: a definition of a tree; where and how trees grow; flowers, pollination and seed production; how trees make their food; how to recognize trees; seasonal changes;…

  7. Juvenility and serial vegetative propagation of Norway spruce clones (Picea abies Karst.).

    Treesearch

    J.B. St. Clair; J. Kleinschmit; J. Svolba

    1985-01-01

    Effects associated with progressive maturation of clones are of greatest concern in clonal tree improvement programs. Serial propagation has been in use at the Lower Saxony Forest Research Institute since 1968 to arrest maturation in Norway spruce clones. By 1980 cuttings were established in the nursery that had been serially propagated from one to five cycles. This...

  8. Cultivar identification and genetic relatedness among 25 black walnut (Juglans nigra) clones based on microsatellite markers

    Treesearch

    Kejia Pang; Keith Woeste; Charles. Michler

    2017-01-01

    A set of eight microsatellite markers was used to genotype 25 black walnut (Juglans nigra L.) clones within the Purdue University germplasm repository. The identities of 212 ramets were verified using the same eight microsatellite markers. Some trees were mislabeled and corrected as to clone using analysis of microsatellite markers. A genetic...

  9. Populus species and hybrid clones resistant to Melampsora, Marssonina, and Septoria.

    Treesearch

    Michael E. Ostry; Harold S. Jr. McNabb

    1986-01-01

    Trees were rated for their resistance to the foliar pathogens Melampsora medusae and Marssonina brunnea and the foliar and canker pathogen Septoria musiva. Many clones were found to be too susceptible to one or more diseases to be safely planted in the north central United States. The P. X euramericana clones...

  10. Cloning, killing, and identity.

    PubMed Central

    McMahan, J

    1999-01-01

    One potentially valuable use of cloning is to provide a source of tissues or organs for transplantation. The most important objection to this use of cloning is that a human clone would be the sort of entity that it would be seriously wrong to kill. I argue that entities of the sort that you and I essentially are do not begin to exist until around the seventh month of fetal gestation. Therefore to kill a clone prior to that would not be to kill someone like you or me but would be only to prevent one of us from existing. And even after one of us begins to exist, the objections to killing it remain comparatively weak until its psychological capacities reach a certain level of maturation. These claims support the permissibility of killing a clone during the early stages of its development in order to use its organs for transplantation. PMID:10226909

  11. Tree harvesting

    SciTech Connect

    Badger, P.C.

    1995-12-31

    Short rotation intensive culture tree plantations have been a major part of biomass energy concepts since the beginning. One aspect receiving less attention than it deserves is harvesting. This article describes an method of harvesting somewhere between agricultural mowing machines and huge feller-bunchers of the pulpwood and lumber industries.

  12. Tree Mortality

    Treesearch

    Mark J. Ambrose

    2012-01-01

    Tree mortality is a natural process in all forest ecosystems. However, extremely high mortality also can be an indicator of forest health issues. On a regional scale, high mortality levels may indicate widespread insect or disease problems. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands....

  13. Tree mortality

    Treesearch

    Mark J. Ambrose

    2013-01-01

    Tree mortality is a natural process in all forest ecosystems. However, extremely high mortality can also be an indicator of forest health issues. On a regional scale, high mortality levels may indicate widespread insect or disease problems. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands....

  14. Tree mortality

    Treesearch

    Mark J. Ambrose

    2013-01-01

    Tree mortality is a natural process in all forest ecosystems. However, extremely high mortality also can be an indicator of forest health issues. On a regional scale, high mortality levels may indicate widespread insect or disease problems. High mortality may also occur if a large proportion of the forests in a region is made up of older, senescent stands.

  15. Motor Creativity of Preschool Children on the London Trestle Tree Apparatus.

    ERIC Educational Resources Information Center

    Lubin, Ellen; Sherrill, Claudine

    The motor creativity of preschoolers when encountering a novel piece of athletic equipment was observed and analyzed. The London Trestle Tree Apparatus, consisting of eight trestles of various sizes, two poles, a rope ladder, two ropes, pommel top, rubber top, balance bar, slide plank, ladder, and beat board was erected for the children to use in…

  16. Motor Creativity of Preschool Children on the London Trestle Tree Apparatus.

    ERIC Educational Resources Information Center

    Lubin, Ellen; Sherrill, Claudine

    The motor creativity of preschoolers when encountering a novel piece of athletic equipment was observed and analyzed. The London Trestle Tree Apparatus, consisting of eight trestles of various sizes, two poles, a rope ladder, two ropes, pommel top, rubber top, balance bar, slide plank, ladder, and beat board was erected for the children to use in…

  17. Initiation of rubber biosynthesis: In vitro comparisons of benzophenone-modified diphosphate analogues in three rubber-producing species.

    PubMed

    Xie, Wenshuang; McMahan, Colleen M; Degraw, Amanda J; Distefano, Mark D; Cornish, Katrina; Whalen, Maureen C; Shintani, David K

    2008-10-01

    Natural rubber, cis-1,4-polyisoprene, is a vital industrial material synthesized by plants via a side branch of the isoprenoid pathway by the enzyme rubber transferase. While the specific structure of this enzyme is not yet defined, based on activity it is probably a cis-prenyl transferase. Photoactive functionalized substrate analogues have been successfully used to identify isoprenoid-utilizing enzymes such as cis- and trans-prenyltransferases, and initiator binding of an allylic pyrophosphate molecule in rubber transferase has similar features to these systems. In this paper, a series of benzophenone-modified initiator analogues were shown to successfully initiate rubber biosynthesis in vitro in enzymatically-active washed rubber particles from Ficus elastica, Heveabrasiliensis and Parthenium argentatum. Rubber transferases from all three species initiated rubber biosynthesis most efficiently with farnesyl pyrophosphate. However, rubber transferase had a higher affinity for benzophenone geranyl pyrophosphate (Bz-GPP) and dimethylallyl pyrophosphate (Bz-DMAPP) analogues with ether-linkages than the corresponding GPP or DMAPP. In contrast, ester-linked Bz-DMAPP analogues were less efficient initiators than DMAPP. Thus, rubber biosynthesis depends on both the size and the structure of Bz-initiator molecules. Kinetic studies thereby inform selection of specific probes for covalent photolabeling of the initiator binding site of rubber transferase.

  18. Identification and reconstitution of the rubber biosynthetic machinery on rubber particles from Hevea brasiliensis

    PubMed Central

    Yamashita, Satoshi; Yamaguchi, Haruhiko; Waki, Toshiyuki; Aoki, Yuichi; Mizuno, Makie; Yanbe, Fumihiro; Ishii, Tomoki; Funaki, Ayuta; Tozawa, Yuzuru; Miyagi-Inoue, Yukino; Fushihara, Kazuhisa; Nakayama, Toru; Takahashi, Seiji

    2016-01-01

    Natural rubber (NR) is stored in latex as rubber particles (RPs), rubber molecules surrounded by a lipid monolayer. Rubber transferase (RTase), the enzyme responsible for NR biosynthesis, is believed to be a member of the cis-prenyltransferase (cPT) family. However, none of the recombinant cPTs have shown RTase activity independently. We show that HRT1, a cPT from Heveabrasiliensis, exhibits distinct RTase activity in vitro only when it is introduced on detergent-washed HeveaRPs (WRPs) by a cell-free translation-coupled system. Using this system, a heterologous cPT from Lactucasativa also exhibited RTase activity, indicating proper introduction of cPT on RP is the key to reconstitute active RTase. RP proteomics and interaction network analyses revealed the formation of the protein complex consisting of HRT1, rubber elongation factor (REF) and HRT1-REF BRIDGING PROTEIN. The RTase activity enhancement observed for the complex assembled on WRPs indicates the HRT1-containing complex functions as the NR biosynthetic machinery. DOI: http://dx.doi.org/10.7554/eLife.19022.001 PMID:27790974

  19. A computational study of adhesion between rubber and metal sulfides at rubber-brass interface

    NASA Astrophysics Data System (ADS)

    Ling, Chian Ye; Hirvi, Janne T.; Suvanto, Mika; Bazhenov, Andrey S.; Ajoviita, Tommi; Markkula, Katriina; Pakkanen, Tapani A.

    2015-05-01

    Computational study at level of density functional theory has been carried out in order to investigate the adhesion between rubber and brass plated steel cord, which has high importance in tire manufacturing. Adsorption of natural rubber based adsorbate models has been studied on zinc sulfide, ZnS(1 1 0), and copper sulfide, Cu2S(1 1 1) and CuS(0 0 1), surfaces as the corresponding phases are formed in adhesive interlayer during rubber vulcanization. Saturated hydrocarbons exhibited weak interactions, whereas unsaturated hydrocarbons and sulfur-containing adsorbates interacted with the metal atoms of sulfide surfaces more strongly. Sulfur-containing adsorbates interacted with ZnS(1 1 0) surface stronger than unsaturated hydrocarbons, whereras both Cu2S(1 1 1) and CuS(0 0 1) surfaces showed opposite adsorption preference as unsaturated hydrocarbons adsorbed stronger than sulfur-containing adsorbates. The different interaction strength order can play role in rubber-brass adhesion with different relative sulfide concentrations. Moreover, Cu2S(1 1 1) surface exhibits higher adsorption energies than CuS(0 0 1) surface, possibly indicating dominant role of Cu2S in the adhesion between rubber and brass.

  20. Identification and reconstitution of the rubber biosynthetic machinery on rubber particles from Hevea brasiliensis.

    PubMed

    Yamashita, Satoshi; Yamaguchi, Haruhiko; Waki, Toshiyuki; Aoki, Yuichi; Mizuno, Makie; Yanbe, Fumihiro; Ishii, Tomoki; Funaki, Ayuta; Tozawa, Yuzuru; Miyagi-Inoue, Yukino; Fushihara, Kazuhisa; Nakayama, Toru; Takahashi, Seiji

    2016-10-28

    Natural rubber (NR) is stored in latex as rubber particles (RPs), rubber molecules surrounded by a lipid monolayer. Rubber transferase (RTase), the enzyme responsible for NR biosynthesis, is believed to be a member of the cis-prenyltransferase (cPT) family. However, none of the recombinant cPTs have shown RTase activity independently. We show that HRT1, a cPT from Heveabrasiliensis, exhibits distinct RTase activity in vitro only when it is introduced on detergent-washed HeveaRPs (WRPs) by a cell-free translation-coupled system. Using this system, a heterologous cPT from Lactucasativa also exhibited RTase activity, indicating proper introduction of cPT on RP is the key to reconstitute active RTase. RP proteomics and interaction network analyses revealed the formation of the protein complex consisting of HRT1, rubber elongation factor (REF) and HRT1-REF BRIDGING PROTEIN. The RTase activity enhancement observed for the complex assembled on WRPs indicates the HRT1-containing complex functions as the NR biosynthetic machinery.

  1. On cloning human beings.

    PubMed

    de Melo-Martin, Inmaculada

    2002-06-01

    The purpose of this paper is to show that arguments for and against cloning fail to make their case because of one or both of the following reasons: 1) they take for granted customary beliefs and assumptions that are far from being unquestionable; 2) they tend to ignore the context in which human cloning is developed. I will analyze some of the assumptions underlying the main arguments that have been offered for and against cloning. Once these assumptions are critically analyzed, arguments both rejecting and supporting human cloning seem to lose weight. I will first briefly present the main arguments that have been proposed against cloning and I will argue that they fail to establish their case. In the next section I will evaluate some of the positive arguments that have been offered supporting such technology. This analysis will show that the case for cloning also fails. Finally, I will maintain that because critics and especially supporters of this technology neglect the context in which human cloning is developed and might be implemented, their arguments are far from compelling.

  2. [Human cloning or cannibalism].

    PubMed

    Sokolowski, L M

    2001-01-01

    In this article I develop the idea presented in my previous work that human cloning would be of little practical use since almost any aim that one would like to attain by multiple cloning of a concrete man or a group of people, are unattainable or it might be achieved by easier, cheaper and more efficient traditional methods. For this reason cloning of a man is unlikely to occur on a larger scale and only few people will decide to clone themselves. In this sense no social effects of human cloning will be disastrous for the human population. Yet investigations in human genetics are very important since they may provide medical applications far more important than human cloning. It is argued that the main trend of modern medicine: organ transplantation from an alien donor, will become socially dangerous in near future since the number of donors will be drastically smaller than the number of potential patients waiting for transplantations. This in turn may cause social conflicts and a form of medical cannibalism may arise. These problems and conflicts will be avoided if organ transplantation from an alien donor is replaced by organ cloning, i.e. by transplanting an organ developed from the patient.

  3. Shape memory rubber bands & supramolecular ionic copolymers

    NASA Astrophysics Data System (ADS)

    Brostowitz, Nicole

    The primary focus of this dissertation is to understand the thermo-mechanical properties that govern shape memory in rubber blends. An ideal shape memory polymer (SMP) has a large entropic component that drives shape recovery with a distinct transition mechanism to control the recovery conditions. Polyisoprene rubber is highly elastic and shows shape memory behavior through strain induced crystallization above its glass transition temperature. However, this transition temperature is below 0°C and not suitable for most applications. Shape memory blends can tailor the transition temperature through selection of the switching phase. Most SMP blends require complicated synthesis routes or intensive compounding which would be inhibitive for production. A facile method was developed for fabrication of a robust shape memory polymer by swelling cross-linked natural rubber with stearic acid. Thermal, microscopic studies showed that stearic acid formed a percolated network of crystalline platelets within the natural rubber. Further investigation of the material interactions was carried out with a low molecular weight polyisoprene analog, squalene, and stearic acid gel. Tensile tests on the rubber band demonstrated the thermo-mechanical effect of swelling with stearic acid. Low hysteresis was observed under cyclic loading which indicated viability for the stearic acid swollen rubber band as an SMP. The microscopic crystals and the cross-linked rubber produce a temporary network and a permanent network, respectively. These two networks allow thermal shape memory cycling with deformation and recovery above the melting point of stearic acidand fixation below that point. Under manual, strain-controlled tensile deformation, the shape memory rubber bands exhibited fixity and recovery of 100% +/- 10%. The recovery properties of the SMP were studied under various loading conditions and a model was fit to describe the potential recovery with relation to the fixation. An additional

  4. Trapped rubber processing for advanced composites

    NASA Technical Reports Server (NTRS)

    Marra, P. J.

    1976-01-01

    Trapped rubber processing is a molding technique for composites in which precast silicone rubber is placed within a closed cavity where it thermally expands against the composite's surface supported by the vessel walls. The method has been applied by the Douglas Aircraft Company, under contract to NASA-Langley, to the design and fabrication of 10 DC-10 graphite/epoxy upper aft rudder assemblies. A three-bay development tool form mold die has been designed and manufactured, and tooling parameters have been established. Fabrication procedures include graphite layup, assembly of details in the tool, and a cure cycle. The technique has made it possible for the cocured fabrication of complex primary box structures otherwise impracticable via standard composite material processes.

  5. Occupational disease in the rubber industry.

    PubMed

    Peters, J M; Monson, R R; Burgess, W A; Fine, L J

    1976-10-01

    We have studied mortality patterns in a large cohort of rubber workers. We have examined workers exposed to curing fumes, processing dusts, and industrial talc and have begun to evaluate exposures of these workers in detail. Gastrointestinal (especially stomach) cancer appears in excess in processing workers. Lung cancer is excessive in curing workers. Leukemia is increased generally. All three groups studied for respiratory disease have an increase in disease prevalence which is related to intensity and duration of exposure. Since both an increase in stomach cancer and respiratory disease is seen in processing workers, exposures in this area must be controlled. Since both lung cancer and chronic respiratory disease is excessive in curing rooms, this exposure must be controlled. The leukemia risk is probably related to solvents. Whether this is all explainable by past benzene exposure is unknown. Further studies are planned to refine our knowledge concerning these risks so that occupational disease in the rubber industry can be prevented.

  6. Occupational disease in the rubber industry.

    PubMed Central

    Peters, J M; Monson, R R; Burgess, W A; Fine, L J

    1976-01-01

    We have studied mortality patterns in a large cohort of rubber workers. We have examined workers exposed to curing fumes, processing dusts, and industrial talc and have begun to evaluate exposures of these workers in detail. Gastrointestinal (especially stomach) cancer appears in excess in processing workers. Lung cancer is excessive in curing workers. Leukemia is increased generally. All three groups studied for respiratory disease have an increase in disease prevalence which is related to intensity and duration of exposure. Since both an increase in stomach cancer and respiratory disease is seen in processing workers, exposures in this area must be controlled. Since both lung cancer and chronic respiratory disease is excessive in curing rooms, this exposure must be controlled. The leukemia risk is probably related to solvents. Whether this is all explainable by past benzene exposure is unknown. Further studies are planned to refine our knowledge concerning these risks so that occupational disease in the rubber industry can be prevented. PMID:1026415

  7. Extraction of mercaptobenzothiazole compounds from rubber products.

    PubMed

    Hansson, C; Bergendorff, O; Ezzelarab, M; Sterner, O

    1997-04-01

    At evaluation of contact dermatitis caused by solid material, patch testing is usually performed with the material as such and with extracts of it. In this study, optimization of the extraction technique monitored by quantitative HPLC analysis of the extracted haptens is described for mercaptobenzothiazole derivatives. Several solvents with different properties are included. Acetone has traditionally been a solvent widely used for the extraction of organic haptens from solid products. However, acetone and other ketones are not inert solvents. The rubber accelerators 2-(4-morpholinyl mercapto) benzothiazole (MMBT) and N-cyclohexyl-2-benzothiazyl sulfenamide (CBS) react with acetone, yielding 2 new compounds, which were isolated and characterised by NMR and MS. For the extraction of solid rubber products, methyl tert-butyl ether (MTBE) was found to be a more suitable solvent which is unreactive to most common haptens.

  8. On the response of rubbers at high strain rates.

    SciTech Connect

    Niemczura, Johnathan Greenberg

    2010-02-01

    In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.

  9. Rubber plantations act as water pumps in tropical China

    NASA Astrophysics Data System (ADS)

    Tan, Zheng-Hong; Zhang, Yi-Ping; Song, Qing-Hai; Liu, Wen-Jie; Deng, Xiao-Bao; Tang, Jian-Wei; Deng, Yun; Zhou, Wen-Jun; Yang, Lian-Yan; Yu, Gui-Rui; Sun, Xiao-Min; Liang, Nai-Shen

    2011-12-01

    Whether rubber plantations have the role of water pumps in tropical Southeast Asia is under active debate. Fifteen years (1994-2008) of paired catchments water observation data and one year paired eddy covariance water flux data in primary tropical rain forest and tropical rubber plantation was used to clarify how rubber plantation affects local water resources of Xishuangbanna, China. Both catchment water observations and direct eddy covariance estimates indicates that more water was evapotranspired from rubber plantation (1137 mm based on catchment water balance, 1125 mm based on eddy covariance) than from the rain forest (969 mm based on catchment water balance, 927 mm based on eddy covariance). Soil water storage during the rainy season is not sufficient to maintain such high evapotranspiration rates, resulting in zero flow and water shortages during the dry season in the rubber plantation. Therefore, this study supports the idea that rubber plantations act as water pumps as suggested by local inhabitants.

  10. Tree Nut Allergies

    MedlinePlus

    ... Luncheon Registration Create Your Own Events Educational Events Tree Nut Allergies Tree nut allergy is one of ... with tree nuts during manufacturing and processing. Avoiding Tree Nuts The federal Food Allergen Labeling and Consumer ...

  11. Silicone-Rubber Tooling for Hollow Panels

    NASA Technical Reports Server (NTRS)

    Gallimore, F. H.

    1985-01-01

    Wave-free contour surface obtained by using flexible mold. Silicone-rubber layup tool, when used in conjunction with hard plastic laminating mold defining desired contour, produces panel with wave-free surface that accurately reproduces shape of mold. In addition to providing porous hollow-panel wing structure that acts as duct for transporting sucked boundary layer tooling, also used to fabricate high-strength lightweight door panels and any single-or compound-contour panel.

  12. Rubber-Modified Epoxies: Transitions and Morphology.

    DTIC Science & Technology

    1980-09-01

    Table 2. Composition and Cure of Model Resins: Notation. Table 3. Morphology: Summary. FIGURE CAPTIONS Fig. 1. TBA damping curves for unmodified and...temperature of cure and the gelation time. These DD 1473 om~ow* orimv as to .gews ~ 410 3 ? U611111Iry OLASSIPCATSWor TISite Answ IO - ------ AIR- SECURITV...rubber, the temperature of cure and the gelation time. These ideas have been exploited to control the development of morphology of these amorphous

  13. 76 FR 28502 - Cooper Tire & Rubber Tire Company, Receipt of Petition for Decision of Inconsequential Noncompliance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-17

    ... National Highway Traffic Safety Administration Cooper Tire & Rubber Tire Company, Receipt of Petition for Decision of Inconsequential Noncompliance Cooper Tire & Rubber Tire Company, (Cooper),\\1\\ has determined...\\ Cooper Tire & Rubber Tire Company (Cooper) is a replacement equipment manufacturer incorporated in...

  14. 75 FR 36472 - Goodyear Tire and Rubber Company, Receipt of Petition for Decision of Inconsequential Noncompliance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-25

    ... National Highway Traffic Safety Administration Goodyear Tire and Rubber Company, Receipt of Petition for Decision of Inconsequential Noncompliance Goodyear Tire and Rubber Company, (Goodyear),\\1\\ has determined... 573, Defect and Noncompliance Responsibility and Reports. \\1\\ Goodyear Tire and Rubber...

  15. 75 FR 81712 - The Goodyear Tire & Rubber Company, Receipt of Petition for Decision of Inconsequential...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-28

    ... National Highway Traffic Safety Administration The Goodyear Tire & Rubber Company, Receipt of Petition for Decision of Inconsequential Noncompliance The Goodyear Tire & Rubber Company (Goodyear) \\1\\ has determined... Noncompliance Responsibility and Reports, dated August 12, 2010. \\1\\ The Goodyear Tire & Rubber...

  16. Magnesium affects rubber biosynthesis and particle stability in Ficus elastica, Hevea brasiliensis and Parthenium argentatum

    USDA-ARS?s Scientific Manuscript database

    Natural rubber biosynthesis occurs in laticifers of Ficus elastica and Hevea brasiliensis, and in parenchyma cells of Parthenium argentatum. Natural rubber is synthesized by rubber transferase using allylic pyrophosphates as initiators, isopentenyl pyrophosphate as monomeric substrate and magnesium ...

  17. SSR Fingerprinting Panel Verifies Identities of Clones in Backup Hazelnut Collection of USDA Genebank

    USDA-ARS?s Scientific Manuscript database

    The US Department of Agriculture (USDA), Agricultural Research Service maintains a genebank representing world hazelnut (Corylus L.) diversity. More than 670 clones are preserved as self-rooted trees in a two-hectare field planting in Corvallis, Oregon, with a single tree per accession. In 1996 an...

  18. SSR Fingerprinting Panel Verifies Identities of Clones in Backup Hazelnut Collection of USDA Genebank

    USDA-ARS?s Scientific Manuscript database

    The US Department of Agriculture (USDA), Agricultural Research Service maintains a genebank representing world hazelnut (Corylus L.) diversity. More than 670 clones are preserved as self-rooted trees in a two-hectare field planting in Corvallis, Oregon, with a single tree per accession. In 1996 an...

  19. Effects of Carbon Black Type on Breathable Butyl Rubber Membranes

    DTIC Science & Technology

    2006-11-01

    EFFECTS OF CARBON BLACK TYPE ON BREATHABLE BUTYL RUBBER MEMBRANES P. Threepopnatkul, D. Murphy, and J. Mead Department of Plastics Engineering...the formulation effects of carbon black type and carbon black loading on the physical properties of electrospun butyl rubber nonwoven membranes...can be provided by elastomeric materials. On the other hand, butyl rubber films have the ability to stretch and are utilized in chemical protective

  20. The enzymatic synthesis of rubber polymer in Parthenium argentatum Gray

    SciTech Connect

    Benedict, C.R.; Madhavan, S.; Greenblatt, G.A.; Venkatachalam, K.V.; Foster, M.A. )

    1990-03-01

    Washed rubber particles isolated from stem homogenates of Parthenium argentatum Gray by ultracentrifugation and gel filtration on columns of LKB Ultrogel AcA34 contain rubber transferase which catalyzes the polymerization of isopentenyl pyrophosphate into rubber polymer. The polymerization reaction requires Mg{sup 2+} isopentenyl pyrophosphate, and an allylic pyrophosphate. The K{sub m} values for Mg{sup 2+}, isopentenyl pyrophosphate, and dimethylallyl pyrophosphate were 5.2 {times} 10{sup {minus}4} molar, 8.3 {times} 10{sup {minus}5} molar, and 9.6 {times} 10{sup {minus}5} molar, respectively. The molecular characteristics of the rubber polymer synthesized from ({sup 14}C)isopentenyl pyrophosphate were examined by gel permeation chromatography. The peak molecular weight of the radioactive polymer increased from 70,000 in 15 minutes to 750,000 in 3 hours. The weight average molecular weight of the polymer synthesized over a 3 hour period was 1.17 {times} 10{sup 6} compared to 1.49 {times} 10{sup 6} for the natural rubber polymer extracted from the rubber particles. Over 90% of the in vitro formation of the rubber polymer was de novo from dimethylallyl pyrophosphate and isopentenyl pyrophosphate. Treatment of the washed rubber particles with 3-((3-cholamidopropyl) dimethylammonio) -1-propanesulfonate solubilized the rubber transferase. The solubilized enzyme(s) catalyzed the polymerization of isopentenyl pyrophosphate into rubber polymer with a peak molecular weight of 1 {times} 10{sup 5} after 3 hours of incubation with Mg{sup 2+} and dimethylallyl pyrophosphate. The data support the conclusion that the soluble preparation of rubber transferase is capable of catalyzing the formation of a high molecular weight rubber polymer from an allylic pyrophosphate initiator and isopentenyl pyrophosphate monomer.

  1. Characterization of interaction between natural rubber and silica by FTIR

    NASA Astrophysics Data System (ADS)

    Jarnthong, Methakarn; Liao, Lusheng; Zhang, Fuquan; Wang, Yueqiong; Li, Puwang; Peng, Zheng; Malawet, Chutarat; Intharapat, Punyanich

    2017-05-01

    Blending of natural rubber (NR) and nanosilica (SiO2) was performed in latex state. The mechanical properties of NR/SiO2 nanocomposites at various filler contents were investigated. The interactions of unvulcanized natural rubber and nanosilica filler were characterized using Fourier Transform Infrared (FTIR)-Attenuated Total Reflectance (ATR) spectroscopy. The relationship between mechanical properties and rubber-filler interaction was discussed.

  2. Development of Improved Rubber Compounds for Use in Weapon Applications

    DTIC Science & Technology

    1974-08-01

    product Paracril D. Compound formulations and physical properties are listed Jn Tab s 10 and 11. respectively. The Japanese nitrile rubber was »«T...Fluorosilicone ruDber inserts for use with machine gun springs exhibited better performance than the sllicone rubber now specified. Blends of...failure. Recently introduced Japanese nitrile rubber and two domestic nitriles did not exhibit any highly significant improvement over nitrile

  3. Mortality among rubber workers: V. processing workers.

    PubMed

    Delzell, E; Monson, R R

    1982-07-01

    Cause-specific mortality was evaluated among 2,666 men employed in the processing division of a rubber manufacturing plant. The division was divided into two sections: front processing (compounding, mixing and milling operations) and back processing (extrusion, calendering, cement mixing and rubberized fabrics operations). Mortality rates for all processing workers combined and for men in each section were compared with rates for U.S. White males or for workers employed in other divisions of the same plant. Compared with either referent group, men in the processing division had increased mortality from leukemia, emphysema, and cancers of the stomach, large intestine, and biliary passages and liver. An excess number of deaths from stomach and larger intestine cancer was found predominantly among men in the front processing section (33 observed vs. 17.7 expected deaths, based on rates in nonprocessing workers). Increased mortality from leukemia (14 observed vs. 7.3 expected) and from emphysema (22 observed vs. 11.0 expected) was present among men employed in the back processing section. Examination of mortality from these causes according to age and the year starting work, duration of employment, and years since starting work in the relevant sections of the processing division suggested that observed excesses of stomach cancer, large intestine cancer, leukemia, and emphysema among processing workers are related to occupational exposures. These results are consistent with the findings of studies of other groups of rubber workers.

  4. Cancer mortality in the British rubber industry.

    PubMed Central

    Parkes, H G; Veys, C A; Waterhouse, J A; Peters, A

    1982-01-01

    Although it is over 30 years since an excess of bladder cancer was first identified in British rubber workers, the fear has persisted that this hazard could still be affecting men working in the industry today. Furthermore, suspicions have also arisen that other and hitherto unsuspected excesses of cancer might be occurring. For these reasons 33 815 men, who first started work in the industry between 1 January 1946 and 31 December 1960, have been followed up to 31 December 1975 to ascertain the number of deaths attributable to malignant disease and to compare these with the expected number calculated from the published mortality rates applicable to the male population of England and Wales and Scotland. The findings confirm the absence of any excess mortality from bladder cancer among men entering the industry after 1 January 1951 (the presumed bladder carcinogens were withdrawn from production processes in July 1949), but they confirm also a statistically significant excess of both lung and stomach cancer mortality. A small excess of oesophageal cancer was also observed in both the tyre and general rubber goods manufacturing sectors. American reports of an excess of leukaemia among rubber workers receive only limited support from the present study, where a small numerical excess of deaths from leukaemia is not statistically significant. A special feature of the study is the adoption of an analytical method that permits taking into account the long latent period of induction of occupational cancer. PMID:7093147

  5. High Performance Graphene Oxide Based Rubber Composites

    NASA Astrophysics Data System (ADS)

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-08-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

  6. High Performance Graphene Oxide Based Rubber Composites

    PubMed Central

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-01-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

  7. High performance graphene oxide based rubber composites.

    PubMed

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-01-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

  8. Coupled Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    NASA Technical Reports Server (NTRS)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2000-01-01

    A procedure that models coupled thermo-mechanical deformations of viscoelastic rubber cylinders by employing the ABAQUS finite element code is described. Computational simulations of hysteretic heating are presented for several tall and short rubber cylinders both with and without a steel disk at their centers. The cylinders are compressed axially and are then cyclically loaded about the compressed state. The non-uniform hysteretic heating of the rubber cylinders containing a steel disk is presented. The analyses performed suggest that the coupling procedure should be considered for further development as a design tool for rubber degradation studies.

  9. Analysis of residual vulcanization accelerators in baby bottle rubber teats.

    PubMed

    Yamazaki, T; Inoue, T; Yamada, T; Tanimura, A

    1986-01-01

    An analytical method was established for the determination of dialkyldithiocarbamates (DTCs) in chloroform-acetone extracts from rubber teats for baby bottles. DTCs in the extracts were derivatized into ethyl esters and analysed by gas chromatography employing nitrogen-phosphorus detection. Dimethyldithiocarbamate and diethyldithiocarbamate were detected at levels up to 3.2 micrograms/g rubber and up to 4.6 micrograms/g rubber (as dithiocarbamic acid), respectively, in the extracts from commercially available isoprene rubber tests. DTCs can form secondary amines by acid hydrolysis, although the levels of DTCs in the extracts only made a minor contribution to the total level of measured secondary amine precursors.

  10. Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

    NASA Astrophysics Data System (ADS)

    Shahidi, Nima

    Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media

  11. Influence of ferrous materials on crumb rubber modified asphalts

    NASA Astrophysics Data System (ADS)

    Capelo, M.; Reina, V.; Naranjo, F.; Carrión, L.; Arroyo, Carlos R.; Narváez-Muñoz, C.

    2017-09-01

    This research investigated the properties of crumb rubber modified asphalt mixtures, using a wet process. Different size of crumb rubber particles have been used to analyze their effects on modified asphalt. Moreover, two types of crumb rubber were use; one was used without any change (powder 1), while the other one the ferrous material was removed (powder 2). The tests of chemical compositions and microstructure were performed by Scanning electronic microscope (SEM) and optical microscope, respectively. Finally, the results obtained confirm that the rheology of this modified asphalt depends on the chemical compositions of the crumb rubber at low temperatures.

  12. High temperature performance of scrap tire rubber modified asphalt concrete

    SciTech Connect

    Coomarasamy, A.; Manolis, S.; Hesp, S.

    1996-12-31

    Wheel track rutting tests on mixes modified with 30 mesh, 80 mesh, and very fine colloidal crumb rubber particles show that a very significant improvement in performance occurs with a reduction in the rubber particle size. The SHRP binder test for rutting, which was originally developed for homogeneous systems only, does not predict the performance improvement for smaller rubber particles. If these new scrap rubber binder systems are to be used in pavements then rutting tests on the asphalt-aggregate mixture should be conducted in order to accurately predict high temperature performance.

  13. Radiation vulcanization of natural rubber latex with polyfunctional monomers

    SciTech Connect

    Makuuchi, K.; Hagiwara, M.

    1984-03-01

    Natural rubber latex was irradiated with ..gamma..-rays from Co-60 in the presence of polyfunctional monomers to accelerate crosslinking of rubber molecules. Hydrophobic monomers were more effective in accelerating the vulcanization than were hydrophilic monomers. This was ascribed to high solubility of hydrophobic monomers in rubber particles. Among the hydrophobic monomers, neopentylglycol dimethacrylate (NPG) exhibited the highest efficiency in accelerating the vulcanization. Advantages of using NPG are high colloidal stability of the irradiated latex and high thermal stability of dried rubber film.

  14. Isolation of Microorganisms Able To Metabolize Purified Natural Rubber

    PubMed Central

    Heisey, R. M.; Papadatos, S.

    1995-01-01

    Bacteria able to grow on purified natural rubber in the absence of other organic carbon sources were isolated from soil. Ten isolates reduced the weight of vulcanized rubber from latex gloves by >10% in 6 weeks. Scanning electron microscopy clearly revealed the ability of the microorganisms to colonize, penetrate, and dramatically alter the physical structure of the rubber. The rubber-metabolizing bacteria were identified on the basis of fatty acid profiles and cell wall characteristics. Seven isolates were strains of Streptomyces, two were strains of Amycolatopsis, and one was a strain of Nocardia. PMID:16535106

  15. Characterization of some selected vulcanized and raw silicon rubber materials

    NASA Astrophysics Data System (ADS)

    Sasikala, A.; Kala, A.

    2017-06-01

    Silicone Rubber is a high need of importance of Medical devices, Implants, Aviation and Aerospace wiring applications. Silicone rubbers are widely used in industry, and there are in multiple formulations. A raw and vulcanized silicone rubber Chemical and Physical structures of particles was confirmed and mechanical strength has been analyzed by FTIR spectroscopy. Thermal properties studied from Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analysis. Activation energy of the rubber materials were calculated using Broido method, Piloyon-Novikova relation and coats-Red fern methods.

  16. [Contamination of solid-cast rubber tires by microscopic fungi].

    PubMed

    Chuienko, A I; Subbota, A H; Olishevs'ka, S V; Zaslavs'kyĭ, V A; Zhdanova, N M

    2010-01-01

    The main peculiarities of fungal resistance of two types of unit cast rubber tires of domestic manufacture have been investigated. Rubber tires which contained synthetic plasticizer were non-resistant to fungal contamination in contrast to ones with natural plasticizer. Using the method of confocal laser-scanning microscopy, it was shown that inner layers of two types of rubber tires were contaminated with fungal mycelium. Our findings indicate that the investigation of microscopic fungi resistance of new materials is necessary for general mechanical rubber goods, especially exported to tropical climate countries.

  17. On Thermophysical Properties of Rubbers and Their Components

    NASA Astrophysics Data System (ADS)

    Danilova-Tret‧yak, S. M.

    2016-11-01

    Results of investigation of the thermophysical properties of commercial carbon of different grades used in the production of tires, and also of rubber mixtures, including those containing karelite, have been presented. A thermal analysis (thermogravimetry, differential thermal analysis) was made of samples of rubber mixtures and powdered fillers, which has enabled the author to establish the distinctive features of thermal stability of materials. The obtained results are important for a better understanding of the problem of critical overheating of supergiant tires, solution of the problem of selecting the optimum compositions of rubber mixtures, and updating the technologies of production and utilization of rubber products.

  18. Technical Tree Climbing.

    ERIC Educational Resources Information Center

    Jenkins, Peter

    Tree climbing offers a safe, inexpensive adventure sport that can be performed almost anywhere. Using standard procedures practiced in tree surgery or rock climbing, almost any tree can be climbed. Tree climbing provides challenge and adventure as well as a vigorous upper-body workout. Tree Climbers International classifies trees using a system…

  19. Effect of pretreatment of rubber material on its biodegradability by various rubber degrading bacteria.

    PubMed

    Berekaa, M M; Linos, A; Reichelt, R; Keller, U; Steinbüchel, A

    2000-03-15

    The effect of pretreatment of several cis-1,4-polyisoprene containing rubbers on their biodegradability was examined. Tests were carried out with six recently isolated and characterized rubber degrading bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas. All strains were able to use natural rubber (NR) as well as NR latex gloves as sole carbon source. Extraction of NR latex gloves by organic solvents resulted in an enhancement of growth for three of the selected strains. On the other hand, growth of Gordonia sp. (strain Kb2 and Kd2), Mycobacterium fortuitum NF4 and Micromonospora aurantiaca W2b on synthetic cis-1,4-polyisoprene did only occur after removal of the antioxidants, that are usually added during manufacture to prevent aging of the materials. Detailed degradation studies performed with Gordonia sp. Kb2 revealed an enhanced mineralization of pretreated NR latex gloves and mineralization of purified natural rubber (NR), indicating the actual mineralization of cis-1,4-polyisoprene rubber constituent even after removal of non-rubber constituent that may act as co-metabolic substrate and support microbial growth. Further analysis by scanning electron microscopy (SEM) clearly demonstrated the enhanced colonization efficiency of these bacteria towards pretreated NR latex gloves. Colonization was additionally visualized by staining of overgrown NR latex gloves with Schiff's reagent, and the purple color produced in the area of degradation was an evidence for the accumulation of aldehydes containing oligomers. Further enhancement of latex gloves degradation could be achieved after successive replacement of mineral salts medium during cultivation. Thereby, a rapid disintegration of untreated NR latex gloves material was accomplished by Gordonia sp. strain VH2.

  20. Exotic trees.

    PubMed

    Burda, Z; Erdmann, J; Petersson, B; Wattenberg, M

    2003-02-01

    We discuss the scaling properties of free branched polymers. The scaling behavior of the model is classified by the Hausdorff dimensions for the internal geometry, d(L) and d(H), and for the external one, D(L) and D(H). The dimensions d(H) and D(H) characterize the behavior for long distances, while d(L) and D(L) for short distances. We show that the internal Hausdorff dimension is d(L)=2 for generic and scale-free trees, contrary to d(H), which is known to be equal to 2 for generic trees and to vary between 2 and infinity for scale-free trees. We show that the external Hausdorff dimension D(H) is directly related to the internal one as D(H)=alphad(H), where alpha is the stability index of the embedding weights for the nearest-vertex interactions. The index is alpha=2 for weights from the Gaussian domain of attraction and 0

  1. Do Managers Clone Themselves?

    ERIC Educational Resources Information Center

    Baron, Alma S.

    1981-01-01

    A recent questionnaire survey provides statistics on male managers' views of female managers. The author recommends that male managers break out of their cloning behavior and that the goal ought to be a plurality in management. (Author/WD)

  2. Clone clustering by hybridization

    SciTech Connect

    Milosavijevic, A.; Zeremski, M.; Paunesku, T.

    1995-05-01

    DNA sequencing by hybridization (SBH) Format 1 technique is based on experiments in which thousands of short oligomers are consecutively hybridized with dense arrays of clones. In this paper the authors present the description of a method for obtaining hybridization signatures for individual clones that guarantees reproducibility despite a wide range of variations in experimental circumstances, a sensitive method for signature comparison at prespecified significance levels, and a clustering algorithm that correctly identifies clusters of significantly similar signatures. The methods and the algorithm have been verified experimentally on a control set of 422 signatures that originate from 9 distinct clones of known sequence. Experiments indicate that only 30 to 50 oligomer probes suffice for correct clustering. This information about the identity of clones can be used to guide both genomic and cDNA sequencing by SBH or by standard gel-based methods. 12 refs., 5 figs., 2 tabs.

  3. Do Managers Clone Themselves?

    ERIC Educational Resources Information Center

    Baron, Alma S.

    1981-01-01

    A recent questionnaire survey provides statistics on male managers' views of female managers. The author recommends that male managers break out of their cloning behavior and that the goal ought to be a plurality in management. (Author/WD)

  4. Statement on Human Cloning

    MedlinePlus

    ... form Search American Association for the Advancement of Science Statement on Human Cloning Tweet The American Association for the Advancement of Science (AAAS) recognizes the intense debates within our society ...

  5. Statement on Human Cloning

    MedlinePlus

    ... form Search American Association for the Advancement of Science Statement on Human Cloning Tweet The American Association for the Advancement of Science (AAAS) recognizes the intense debates within our society ...

  6. Buffing dust as a filler of carboxylated butadiene-acrylonitrile rubber and butadiene-acrylonitrile rubber.

    PubMed

    Chronska, K; Przepiorkowska, A

    2008-03-01

    Buffing dust from chrome tanned leather is one of the difficult tannery wastes to manage. It is also hazardous to both human health and the environment. The scientific literature rarely reports studies on dust management, especially on its utilization as a filler for elastomers. In this connection we have made an attempt to use this leather waste as a filler for rubbers such as XNBR and NBR. The addition of the buffing dust to rubber mixes brought improvement in mechanical properties, and increase in resistance to thermal ageing as well as in electric conductivity and crosslink density of vulcalizates.

  7. Twins: A cloning experience.

    PubMed

    Prainsack, Barbara; Spector, Tim D

    2006-11-01

    Drawing upon qualitative interviews with monozygotic (identical) twins sharing 100% of their genes, and with dizygotic (fraternal) twins and singletons as control groups, this paper explores what it means to be genetically identical. (The twins interviewed were from the TwinsUK register in London.) In the context of the ongoing debate on human reproductive cloning, it examines questions such as: To what extent do identical twins perceive their emotional and physical bond to be a result of their genetic makeup? What would they think if they had been deliberately created genetically identical? How would they feel about being genetically identical to a person who was born a few years earlier or later? First, our respondents ascribed no great significance to the role of genes in their understanding of what it means to be identical twins. Second, the opinion that human reproductive cloning would "interfere with nature", or "contradict God's will", was expressed by our respondents exclusively on the abstract level. The more our respondents were able to relate a particular invented cloning scenario to their own life-worlds, the lower the prevalence of the argument. Third, for all three groups of respondents, the scenario of having been born in one of the other groups was perceived as strange. Fourth, the aspect that our respondents disliked about cloning scenarios was the potential motives of the cloners. Without equating monozygotic twins directly with "clones", these results from "naturally" genetically identical individuals add a new dimension to what a future cloning situation could entail: The cloned person might possibly (a) perceive a close physical and emotional connection to the progenitor as a blessing; (b) suffer from preconceptions of people who regard physical likeness as a sign of incomplete individuality; and (c) perceive the idea of not having been born a clone of a particular person as unpleasant.

  8. Ozone Ageing of Silicone Rubber and the Effects of Anti-Oxidants on the Ozone Ageing of Nitrile Rubber.

    DTIC Science & Technology

    1981-04-01

    APR 81 UNCLASSIFIED RAE-TM-MAT-369 DRIC-BR-87489 F/G 11/10 NL mEEns MEOMOEEhMImIIIIIIIIIIIEIIIIII 1.0 SIIIII . ’ + 1.8 11112 1.4 11111_L6 l~y k ~IT N i...graphs follow a characteristic curve of ozone attack on rubber. Table I is a representation of the retention of physical properties of the rubbers...TEST) ozone resistance. Silicone rubber. Nitrile rubber. 17. Abstract Work done by others suggested that a rapid lose of physical properties could occur

  9. What Makes a Tree a Tree?

    ERIC Educational Resources Information Center

    NatureScope, 1986

    1986-01-01

    Provides: (1) background information on trees, focusing on the parts of trees and how they differ from other plants; (2) eight activities; and (3) ready-to-copy pages dealing with tree identification and tree rings. Activities include objective(s), recommended age level(s), subject area(s), list of materials needed, and procedures. (JN)

  10. Alloreactive T cell clones.

    PubMed

    Fitch, F W

    1984-01-01

    T cell clones are useful models for studying lymphocyte function both at the level of the individual cell and in interacting systems. Murine cytolytic and non- cytolyic T cell clones have been obtained with relative ease, and the particular procedure used to derive and maintain T cell clones may influence profoundly the characteristics of the resulting cells. The method of choice depends on the specific question to be asked. Although some clones have characteristics that would have been expected on the basis of results observed with bulk cell populations, other clones have rather unexpected properties. Although most T cell clones appear to be either cytolytic or non-cytolytic, this distinction is not always absolute. A high proportion of both cytolytic and non-cytolytic T cell clones have dual reactivity. This is true for cells which by other criteria appear to be true clones. The frequency of such cells is high enough to suggest that most if not all T cells may have reactivity for more than one antigenic determinant or that antigenic determinants recognized by T cells are shared widely and unexpectedly. It is not clear whether one or two different antigen receptors account for such dual reactivity. The nature of the T cell receptor for antigen remains obscure. T cell clones, because of their homogeneous nature, should make it easier to answer these important immunological questions. Although it remains to be determined how many distinct molecules account for the numerous biological activities found in the culture supernatants from antigen-stimulated T cell clones, it is clear that these factors influence several different types of cells that are involved directly and indirectly in immune responses. IL-2 stimulates both cytolytic and non-cytolytic T cells to proliferate. BCSF causes polyclonal activation of B cells, and there may be other factors which influence B cell responses to antigenic stimulation. IL-3 apparently stimulates maturation of immature T cells

  11. New application of crystalline cellulose in rubber composites

    NASA Astrophysics Data System (ADS)

    Bai, Wen

    Rubber without reinforcement has limited applications. The strength of reinforced rubber composites can be ten times stronger than that of unreinforced rubbers. Therefore, rubber composites are widely used in various applications ranging from automobile tires to seals, valves, and gaskets because of their excellent mechanical elastic properties. Silica and carbon black are the two most commonly used reinforcing materials in rubber tires. They are derived from non-renewable materials and are expensive. Silica also contributes to a large amount of ash when used tires are disposed of by incineration. There is a need for a new reinforcing filler that is inexpensive, renewable and easily disposable. Cellulose is the most abundant natural polymer. Native cellulose includes crystalline regions and amorphous regions. Crystalline cellulose can be obtained by removing the amorphous regions with the acid hydrolysis of cellulose because the amorphous cellulose can be hydrolyzed faster than crystalline cellulose. We recently discovered that the partial replacement of silica with microcrystalline cellulose (MCC) provided numerous benefits: (1) low energy consumption for compounding, (2) good processability, (3) strong tensile properties, (4) good heat resistance, and (5) potential for good fuel efficiency in the application of rubber tires. Strong bonding between fillers and a rubber matrix is essential for imparting rubber composites with the desired properties for many specific applications. The bonding between hydrophilic MCC and the hydrophobic rubber matrix is weak and can be improved by addition of a coupling agent or surface modifications of MCC. In this study, MCC was surface-modified with acryloyl chloride or alkenyl ketene dimer (AnKD) to form acrylated MCC (A-MCC) and AnKD-modified MCC (AnKD-MCC). The surface modifications of MCC did not change the integrity and mechanical properties of MCC, but provided functional groups that were able to form covalent linkages with

  12. Trees are good, but…

    Treesearch

    E.G. McPherson; F. Ferrini

    2010-01-01

    We know that “trees are good,” and most people believe this to be true. But if this is so, why are so many trees neglected, and so many tree wells empty? An individual’s attitude toward trees may result from their firsthand encounters with specific trees. Understanding how attitudes about trees are shaped, particularly aversion to trees, is critical to the business of...

  13. Natural Rubber Quantification in Sunflower Using an Automated Solvent Extractor

    USDA-ARS?s Scientific Manuscript database

    Leaves of sunflower (Helianthus annuus) produce a small amount of low molecular weight natural rubber (NR) and this species has potential as a rubber-producing crop plant. Quantifying NR in plant tissue has traditionally been accomplished using Soxhlet or gravimetric methodologies. Accelerated solve...

  14. Mutagenicity of rubber vulcanization gases in Salmonella typhimurium.

    PubMed

    Hedenstedt, A; Ramel, C; Wachtmeister, C A

    1981-01-01

    Gases formed by rubber and rubber additives in the vulcanization process were collected with a laboratory-scale glass apparatus. Mutagenicity testing of the vulcanization gases by the Salmonella/microsome test was conducted with strains TA1535, TA1538, TA98, and TA100 in the absence and presence of a metabolizing system from rat liver homogenates. The mutagenicity of gases derived by heating chloroprene rubber and ethylene propylene rubber was established with both base substitution- and frameshift-sensitive strains and that of a styrene-butadiene rubber was established with the base substitution-sensitive stain TA100. Tests on pyrolysis gases from a butadiene acrylonitrile rubber revealed only toxic effects. Curing systems, additives, and filling materials from various sources were represented in the material. Gases were collected at temperature levels corresponding to both mixing and curing of these particular rubbers in the industrial operations. Attempts were made to correlate the mutagenicity of the gases to the presence of mutagenic components in the rubber mixtures.

  15. Rubber Flooring Impact on Production and Herdlife of Dairy Cows

    USDA-ARS?s Scientific Manuscript database

    Use of rubber flooring in dairies has become popular because of perceived cow comfort. The overall objective of this longitudinal study was to evaluate production, reproduction, and retention of first and second lactations of cows assigned to either rubber (RUB) or concrete (CON) flooring at the fe...

  16. Guayule resin detection and influence on guayule rubber

    USDA-ARS?s Scientific Manuscript database

    Guayule (Parthenium argentatum) is a natural rubber (cis-1,4-polyisoprene) producing crop, native to North America. Guayule also produces organic resins, complex mixtures of terpenes, triglycerides, guayulins, triterpenoids and other components. During natural rubber extraction, guayule resins can b...

  17. Reinforcement of latex rubber by the incorporation of amphiphilic nanoparticles

    USDA-ARS?s Scientific Manuscript database

    Latex rubbers are fabricated from latex suspensions. During the fabrication process, latex particles are bound together while water is removed from the suspension. This report shows the mechanical properties of latex rubbers can be improved by incorporating a small amount of amphiphilic nanoparticle...

  18. Blends of guayule natural rubber latex with commercial latex polymers

    USDA-ARS?s Scientific Manuscript database

    Guayule (Parthenium argentatum) is a woody desert shrub that produces natural rubber, cis-1,4 polyisoprene, by biosynthesis. It is currently cultivated in the southwestern United States as a source of latex and rubber for commercial development. Guayule latex is similar to Hevea latex in polymer mo...

  19. PHA-rubber blends: synthesis, characterization and biodegradation.

    PubMed

    Bhatt, Rachana; Shah, Dishma; Patel, K C; Trivedi, Ujjval

    2008-07-01

    Medium chain length polyhydroxyalkanoates (mcl-PHA) and different rubbers; namely natural rubber, nitrile rubber and butadiene rubber were blended at room temperature using solution blending technique. Blends constituted 5%, 10% and 15% of mcl-PHA in different rubbers. Thermogravimetric analysis of mcl-PHA showed the melting temperature of the polymer around 50 degrees C. Thermal properties of the synthesized blend were studied by Differential Scanning Calorimetry which confirmed effective blending between the polymers. Blending of mcl-PHA with natural rubber led to the synthesis of a different polymer having the melting point of 90 degrees C. Degradation studies of the blends were carried out using a soil isolate, Pseudomonas sp. 202 for 30 days. Extracellular protein concentration as well as OD660 due to the growth of Pseudomonas sp. 202 was studied. The degradation of blended plastic material, as evidenced by % weight loss after degradation and increase in the growth of organism correlated with the amount of mcl-PHA present in the sample. Growth of Pseudomonas sp. 202 resulted in 14.63%, 16.12% and 3.84% weight loss of PHA:rubber blends (natural, nitrile and butadiene rubber). Scanning electron microscopic studies after 30 days of incubation further confirmed biodegradation of the films.

  20. Glass fabric fire barrier for silicone rubber parts

    NASA Technical Reports Server (NTRS)

    Blackmer, K. L.

    1969-01-01

    Preformed knitted glass-fabric covers are placed about silicone rubber items in such a way as to completely isolate them from the effects of adjacent fire. These covers permit retention of the desirable resilient properties of the silicone rubber while forming a very effective fire barrier.