Source Of Latex Research Articles

Comparative transcriptome analysis of high- and low-embryogenic Hevea brasiliensis genotypes reveals involvement of phytohormones in somatic embryogenesis

BackgroundRubber plant (Hevea brasiliensis) is one of the major sources of latex. Somatic embryogenesis (SE) is a promising alterative to its propagation by grafting and seed. Phytohormones have been shown to influence SE in different plant species. However, limited knowledge is available on the role of phytohormones in SE in Hevea. The anther cultures of two Hevea genotypes (Yunyan 73477-YT and Reken 628-RT) with contrasting SE rate were established and four stages i.e., anthers (h), anther induced callus (y), callus differentiation state (f), and somatic embryos (p) were studied. UPLC-ESI-MS/MS and transcriptome analyses were used to study phytohormone accumulation and related expression changes in biosynthesis and signaling genes.ResultsYT showed higher callus induction rate than RT. Of the two genotypes, only YT exhibited successful SE. Auxins, cytokinins (CKs), abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), gibberellins (GAs), and ethylene (ETH) were detected in the two genotypes. Indole-3-acetic acid (IAA), CKs, ABA, and ETH had notable differences in the studied stages of the two genotypes. The differentially expressed genes identified in treatment comparisons were majorly enriched in MAPK and phytohormone signaling, biosynthesis of secondary metabolites, and metabolic pathways. The expression changes in IAA, CK, ABA, and ETH biosynthesis and signaling genes confirmed the differential accumulation of respective phytohormones in the two genotypes.ConclusionThese results suggest potential roles of phytohormones in SE in Hevea.

Durability Variation Among Medical Gloves Made from Existing and New Elastomers Poses a Risk to Public Health.

Despite being an essential line of defense in preventing the spread of diseases, medical glove durability is neither measured routinely nor has standard specifications. In this study, a new glove durability assessment device is used to objectively compare the durability of gloves made of a variety of elastomers from different manufacturers. Results are related to several mechanical tests, including stress relaxation, tensile and tear tests. Overall, natural latex gloves far outperformed those made of synthetic elastomers, and there is great disparity among the different brands of nitrile gloves, some of which do not meet nitrile glove performance requirements. The study includes prototype gloves made from guayule latex, a domestic source of alternative natural rubber latex, currently under commercial development. The guayule gloves outperformed all other gloves tested, including those made from Hevea latex, without posing allergy risks. Mechanical analysis demonstrated that the guayule gloves are as strong as the best alternatives, are softer and more elastic, have better tear strength, and have such low stress relaxation that they cause very little hand fatigue during use. Guayule latex can address the need for domestic production of gloves to resolve supply chain and quality issues and encourage a shift back to natural latex gloves, which will significantly diversify the natural rubber supply.

Tables to LaTeX: structure and content extraction from scientific tables

Scientific documents contain tables that list important information in a concise fashion. Structure and content extraction from tables embedded within PDF research documents is a very challenging task due to the existence of visual features like spanning cells and content features like mathematical symbols and equations. Most existing table structure identification methods tend to ignore these academic writing features. In this paper, we adapt the transformer-based language modeling paradigm for scientific table structure and content extraction. Specifically, the proposed model converts a tabular image to its corresponding LaTeX source code. Overall, we outperform the current state-of-the-art baselines and achieve an exact match accuracy of 70.35 and 49.69% on table structure and content extraction, respectively. Further analysis demonstrates that the proposed models efficiently identify the number of rows and columns, the alphanumeric characters, the LaTeX tokens, and symbols.

Extracting information from (La)TeX source files

Extracting information from (La)TeX source files

Effects of temperature and catalytic reduction of sulfur content on kinematic viscosity and specific gravity of tire pyrolysis oil

Some of the issues that humanity is facing include environmental degradation and an energy crisis. These problems are caused by population growth, rapid industrialization, and large amounts of waste generated as a result of various activities. Disposed tires contribute to landfilling because they do not degrade easily. Natural rubber trees are a source of latex, which is the primary component of tires. Tires can be recycled through pyrolysis to produce char, oil, and gas, but they contain high sulfur content. As a catalyst, 0%, 1.5%, 2.5%, 5%, 7.5% and 10% sodium carbonate of the feed material were used to produce tire pyrolysis oil (TPO). This study involved the investigation of temperature and catalytic sulfur reduction effects on the kinematic viscosity and specific gravity of TPO. These are critical properties to consider when assessing TPO's suitability for use in a diesel engine. The sulfur content decreased with increasing sodium carbonate, the specific gravity of TPO increased with increasing sodium carbonate, and kinematic viscosity decreased with increasing sodium carbonate until the catalyst was 2.5% and then started increasing proportionally with sodium carbonate for temperatures between 15 and 60 °C.

Ionic Liquids Separating Rubber Latex from Guayule.

Danger to rubber trees (Hevea brasiliensis) from South American leaf blight fungus imperils the world’s source of natural latex for essential rubber products. Avoiding latex allergies also requires a non-Hevea latex source. The present methods for removing latex entrapped in the individual cells of guayule plants require environmentally hazardous chemicals. This study proposes a new method for latex extraction from guayule using various ionic liquids (ILs) to dissolve cell walls and release latex, as substantiated by Fourier transform infrared spectroscopy (FTIR) data.

JCB Call for Papers for the Special Issue on “40 Years of Computational Biology: In Honor of Professor Michael Waterman's 80th Birthday”

<i>JCB</i> Call for Papers for the Special Issue on “40 Years of Computational Biology: In Honor of Professor Michael Waterman's 80th Birthday”

Nitrous oxide emissions, N uptake, biomass, and rubber yield in N-fertilized, surface-irrigated guayule

Nitrous oxide (N2O) emissions from N fertilizer applied to row crops makes up a large portion of the greenhouse gas loading to the atmosphere. Guayule (Parthenium argentatum A. Gray) is a desert perennial shrub being promoted for Central Arizona farmers as a source of natural rubber and hypoallergenic latex. Emissions of the greenhouse gas N2O and crop N uptake have not been previously quantified in this multi-year cropping system. A 2.5-year study was conducted on transplanted and surface-irrigated guayule on a Casa Grande sandy loam in Maricopa, AZ to assess the agronomic and environmental responses to N fertilizer application rate. Four N fertilizer rates ranging from 0 to 252 kg N ha−1 were applied as ammonium sulfate in three splits. Nitrous oxide emissions were measured with 1-L vented chambers 34 times over 98 weeks from 17 April 2013 to 6 March 2015 with pauses during winter dormant seasons. Nitrogen rate significantly affected N2O emissions, which ranged from 1.2 to 4.5 kg N ha−1 for the 0 and 252 kg N ha−1 fertilizer rates. Emission factors were 1.5, 1.4, and 1.3 % of the added ammonium sulfate-N emitted as N2O for 84, 168, and 250 kg N ha−1, respectively, which are in the range of those for other better-studied crops such as corn (Zea mays L.) and cotton (Gossypium hirsutum L.) Nitrogen uptake by guayule averaged 191 kg N ha−1 for biomass and rubber yields of 19 Mg ha−1 and 1070 kg ha−1, respectively. There was no effect of N rate on N uptake, biomass, or rubber yields because of initial soil profile nitrate (NO3) levels of 85–150 kg NO3-N ha−1. A N balance of inputs (initial soil NO3, N fertilizer, NO3-N added in irrigation) and outputs (N uptake, N2O, and dinitrogen (N2) emissions) was constructed. Unaccounted-for N was apparently lost as NO3 leaching below the root zone. In conclusion, the informative N2O emissions data presented are the first for guayule, and the N uptake levels reported here can be used in updated, improved N fertilizer recommendations for guayule.

Standardized production of a homogeneous latex enzyme source overcoming seasonality and microenvironmental variables

Calotropis procera produces a milky sap containing proteolytic enzymes. At low concentrations, they induce milk-clotting (60 µg/ml) and to dehair hides (0.05 and 0.1%). A protocol for obtaining the enzymes is reported. The latex was mixed with distilled water and the mixture was cleaned through centrifugation. It was dialyzed with distilled water and centrifuged again to recover the soluble fraction [EP]. The dialyze is a key feature of the process. EP was characterized in terms of protein profile, chemical stability, among other criteria. Wild plants belonging to ten geographic regions and grown in different ecological conditions were used as latex source. Collections were carried out, spaced at three-month, according to the seasons at the site of the study. Proteolytic activity was measured as an internal marker and for determining stability of the samples. EP was also analyzed for metal content and microbiology. EP showed similar magnitude of proteolysis, chromatographic and electrophoretic profiles of proteins. Samples stored at 25 °C exhibited reduced solubility (11%) and proteolytic capacity (11%) after six months. Enzyme autolysis was negligible. Microbiological and metal analyses revealed standard quality of all the samples tested. EP induced milk clotting and hide dehairing after storage for up to six months.

In situ 13CO2 labelling of rubber trees reveals a seasonal shift in the contribution of the carbon sources involved in latex regeneration.

Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help in understanding how rubber trees face this additional C demand. Whole crown 13CO2 pulse labelling was performed on 4-year-old rubber trees in June, when latex production was low, and in October, when it was high. 13C content was quantified in the foliage, phloem sap, wood, and latex. In both labelling periods, 13C was recovered in latex just after labelling, indicating that part of the carbohydrate was directly allocated to latex. However, significant amounts of 13C were still recovered in latex after 100 d and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October, than in June. An improved understanding of C dynamics and the source-sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production.

Characterization and Health Risk Assessment of Exposure to Odorous Pollutants Emitted from Industrial Odor Sources

Odor pollution has a high complaint rate with strong public concern, and industrial production is an important source of this type of pollution in China. To understand odor pollution in industrial parks and to protect the safety of work environments, samples were collected from 14 industrial odor sources and then were analyzed for odorous volatile organic compounds (VOCs) and odor concentration. Based on the field data, the main compounds causing odor were assessed and identified. The cancer and non-cancer risk of odor exposure were correspondingly estimated by the health risk model. These following results were noted. ①The substances discharged from 14 sources were the same, but the content varied greatly. Alkanes and alkenes are the major odorous compounds of fibers and batteries manufacturing and in the synthesis of hydrocarbons, anhydrides, esters, and solvents. Benzene and benzene series in waste gases from refineries, purified terephthalic acid (PTA), and latex sources were the highest. Esters are the main pollutants emitted from activated carbon processing, resin synthesis, and spraying. Carbonyl compounds and sulfides are the main exhaust gases from ceramic manufacturing and additive synthesis. ②Exhaust gases from 14 sources caused strong irritation. The synthesis of lubricating oil additives and latex sources result in severe olfactory stimulation. Ethyl mercaptan, ethyl sulfide, n-butanol, and toluene were the major odorous compounds of lubricating oil additives sources. Styrene, propylbenzene, cumene, butyl acrylate, and 1,3-butadiene were the major odorous compounds of latex sources. ③The carcinogenic risk levels for 14 sources ranged from 3.06×10-7 to 1.06×10-2, expressed as life cancer risk (LCR). Refinery, PTA, ester, and latex sources had the highest carcinogenic risk among the 14 emission sources. The non-carcinogenic risk levels for the 14 sources ranged from 0.02 to 51.66, expressed as hazard index (HI). The total HI of latex synthesis, ester synthesis, petroleum refining, PTA synthesis, and fiber manufacturing has certain non-carcinogenic health risks. Factory boundaries for latex, anhydrides synthesis, and resin synthesis sources have potential carcinogenic risk.

Population dynamics of the main phytophagous and predatory mites associated with rubber tree plantations in the State of Bahia, Brazil

Rubber trees, Hevea brasiliensis, are the main source of latex in the world, being cultivated in several states in Brazil. Calacarus heveae Feres and Tenuipalpus heveae Baker are considered the main pest mites of this crop. In this study, we evaluated the population dynamics of these two phytophagous species and of the most common predatory species during a one-year period on crops of rubber tree clones FDR 5788, CDC 312 and PMB 01, located in Igrapiúna, State of Bahia, northeastern Brazil. The results indicate that outbreaks of C. heveae and T. heveae occur from January to May. Population densities vary among clones, being lower on FDR 5788. Amblyseius perditus Chant and Baker (Phytoseiidae), Parapronematus sp. (Iolinidae) and Agistemus pallinii Matioli, Tavares and Pallini (Stigmaeidae) were the most abundant and frequently encountered predacious species. The population dynamics of these predatory species were related to the abundance of the phytophagous mites. However, the efficacy of these predators to mitigate infestations of phytophagous mites under natural conditions is unresolved due to the high reproductive rate of the phytophagous species.

Pollination of Ficus elastica: India rubber re-establishes sexual reproduction in Singapore

Ficus elastica, otherwise known as India Rubber (although its geographical origins are unclear), was an important source of latex in the early 19th century and was widely cultivated in tropical Asia. Like all figs, F. elastica is dependent on tiny, highly specific wasps for pollination, and detailed studies based out of Singapore in the 1930s suggested that through the loss of its pollinator F. elastica was extinct in the wild. However, around 2005 wild seedlings of F. elastica began appearing in Singapore. We identified the pollinator as Platyscapa clavigera, which was originally described from F. elastica in Bogor in 1885. A visit to Bogor Botanical Gardens revealed that not only was F. elastica being pollinated by P. clavigera in the gardens, but there was clear evidence it had been reproducing naturally there over many decades. Although Singapore has a native fig flora of over 50 species, F. elastica went unpollinated for at least 70 years and probably from the time it was introduced during the 19th century. These observations illustrate the extraordinary specificity of this interaction and, through the fig’s ability to wait for its pollinators, demonstrates one way in which such highly specific interactions can be evolutionarily stable.

Investigation of ethanolamine stabilized natural rubber latex from Taraxacum kok-saghyz and from Hevea brasiliensis using zeta-potential and dynamic light scattering measurements

For pH adjustment and long-term preservation of natural rubber (NR11NR: natural rubber.) latex, the usage of ammonia or KOH is still state of the art. Unfortunately, ammonia has a bad odor, it is volatile and toxic and thus does not provide safe and comfortable handling during the processing of latex. KOH preserved latices on the other hand have a significant tendency to form potassium carbonate when getting in contact with air, which rapidly leads to a decrease of the pH value. To overcome these drawbacks, ethanolamine (ETA22ETA: ethanolamine.) is suggested as a substitutional stabilizer for latex from Hevea brasiliensis (HB33HB: Hevea brasiliensis.) and for latex from Russian dandelion, Taraxacum kok-saghyz (TKS44TKS: Taraxacum kok-saghyz.), a promising crop for an alternative and renewable source of NR latex. However, little is known about the colloidal stability of ETA stabilized latices. To this purpose, zeta-potential measurements were performed to evaluate and compare the electrostatic stability of ETA, ammonia, and KOH preserved latices. In addition, dynamic light scattering was used to determine the particle size distribution of the latex dispersions. The results suggest a comparable stabilizing efficiency of the three chosen preservatives. Zeta-potentials of HB latex were in the range between −93mV and −102mV. For TKS latex taken directly from dandelion roots, lower absolute values were obtained (−84mV to −93mV) as well as for TKS latex gained by extraction (−61mV to −65mV). However, all obtained zeta-potentials are in a range that guarantees sufficient colloidal stability. As a result, we found that ETA seems to be as suitable as ammonia or KOH for pH adjustment of TKS and HB latex, leading to comparable latex dispersion stability.

Quantitative Analysis of AntiHevea brasiliensis Antibody Cross-Reactivity against Taraxacum kok-saghyz Latex Proteins Demonstrates Significantly Reduced Antibody Recognition

The annual plant Taraxacum kok-saghyz, commonly called Russian dandelion, has recently gained commercial attention as an alternative source to the rubber tree, Hevea brasiliensis, for natural rubber latex. While producing rubber of equivalent quality, the potential application of TKS latex for hypoallergenic products remains to be determined. In order to quantify the allergenicity of TKS latex proteins, we compared the extent of anti-Hevea latex polyclonal and monoclonal antibody cross-reactivity toward Hevea latex proteins to that of TKS latex proteins by quantitative ELISA methods and semi-quantitative image densitometry. ELISA measurement of polyclonal antibody recognition toward TKS latex proteins was on the order of one-tenth relative to equal amounts of Hevea latex protein, while recognition by the monoclonal antibody was below 2%. Immunoblots confirmed significantly reduced polyclonal antibody recognition toward TKS latex proteins, in the same range as the cross-reactivity exhibited toward the rubber-producing plant, Lactuca sativa and Glycine max, a non-rubber-producing plant. Despite the presence of cross-reactivity, these quantitative results support TKS as an alternative source of latex that may require lessintensive processing for the reduction of antigenic proteins in the manufacture of hypoallergenic natural rubber latex products.

Production and characterization of hierarchical porous silica made using natural rubber as template: Effects of the template removal methods, the pH of production, and the natural rubber sources

A sol–gel process was used to produce hierarchical porous silica (HPS) with and without the use of natural rubber (NR) particles as a templating material. The effects of the following factors on the pore properties are reported: the template-to-silica ratio, the template removal method (either calcination or solvent extraction), the pH, and the source of the NR latex. HPS with macropores formed when the NR template was used. The template affected only the interspacing of silica agglomerates but not the spacing within them. Calcination proved to be more effective than the solvent extraction in removing the template and did not damage the HPS morphology. The pH affected not only the formation of primary silica particles, but also the interactions between the NR template and the primary silica particles. This reduced the BET surface area and the number of macropores in HPS produced at a higher pH. The latex source (whether from a single plantation or mixed latex from multiple plantations) had barely any effect on the properties of the HPS.

Stress Signaling Responses in Plants.

Stress Signaling Responses in Plants.

Genomic diversity and phylogenetic relationships in the genus Parthenium (Asteraceae)

Guayule (Parthenium argentatum A. Gray) is a perennial woody shrub native to the North American Chihuahuan Desert that holds promise as a sustainable source of natural rubber and hypoallergenic latex. The improvement of guayule for commercial-scale production could be accelerated through genomics-assisted breeding, but such a strategy is severely limited by the paucity of available genomic tools and well-characterized genetic resources. To that end, we used genotyping-by-sequencing (GBS) to simultaneously identify and genotype tens of thousands of single-nucleotide polymorphism (SNP) markers across 62 plant samples from seven wild and cultivated guayule, three Parthenium interspecific hybrid, four mariola (Parthenium incanum Kunth), and one wild quinine (Parthenium integrifolium L.) accession(s) that have been characterized for ploidy level and nuclear genome size in this and a prior study. Phylogenetic analysis using the SNP data identified at least two distinct sources of guayule breeding material in the cultivated accessions, previously unknown multi-species hybrids within two Parthenium hybrid cultivars, and guayule/mariola hybrids within one guayule and one mariola wild collected accession. Similar to previously reported results for guayule and mariola, we observed aneuploidy and multiple ploidy levels among individual plants (mixed ploidy) within three Parthenium interspecific hybrid accessions newly characterized in this study. Nuclear genome size characterization of wild quinine, a first for this species, found an estimated haploid nuclear genome size (5757Mb) for the tetraploid (2n=4x=72) accession that was more than 1.5-fold larger than that of tetraploid (2n=4x=72) guayule or mariola. Together, these results further underscore the need for a comprehensive characterization of available guayule germplasm and sister taxa with both SNP markers and flow cytometry, illustrate the novel utility of GBS for the genus Parthenium, and lay the foundation for genomics-assisted breeding in guayule.

New constitutive latex osmotin-like proteins lacking antifungal activity

Proteins that share similar primary sequences to the protein originally described in salt-stressed tobacco cells have been named osmotins. So far, only two osmotin-like proteins were purified and characterized of latex fluids. Osmotin from Carica papaya latex is an inducible protein lacking antifungal activity, whereas the Calotropis procera latex osmotin is a constitutive antifungal protein. To get additional insights into this subject, we investigated osmotins in latex fluids of five species. Two potential osmotin-like proteins in Cryptostegia grandiflora and Plumeria rubra latex were detected by immunological cross-reactivity with polyclonal antibodies produced against the C. procera latex osmotin (CpOsm) by ELISA, Dot Blot and Western Blot assays. Osmotin-like proteins were not detected in the latex of Thevetia peruviana, Himatanthus drasticus and healthy Carica papaya fruits. Later, the two new osmotin-like proteins were purified through immunoaffinity chromatography with anti-CpOsm immobilized antibodies. Worth noting the chromatographic efficiency allowed for the purification of the osmotin-like protein belonging to H. drasticus latex, which was not detectable by immunoassays. The identification of the purified proteins was confirmed after MS/MS analyses of their tryptic digests. It is concluded that the constitutive osmotin-like proteins reported here share structural similarities to CpOsm. However, unlike CpOsm, they did not exhibit antifungal activity against Fusarium solani and Colletotrichum gloeosporioides. These results suggest that osmotins of different latex sources may be involved in distinct physiological or defensive events.

Feasibility of a guayule commodity chain in the Mediterranean region

Natural rubber demand was 11 million tons in 2014 and is expected to reach 16 million tons by 2025 according to the International Rubber Study Group (IRSG). The expected limitation of natural rubber from Hevea induced an interest for the development of alternative sources of natural rubber. Guayule (Parthenium argentatum Gray L.), being native to the Mexican Chihuahua desert, is a perennial crop of semi-arid area, with the potential of growing in the Mediterranean area. To assess the potential of guayule cultivation, CIRAD (France) and Wageningen University (The Netherlands) have conducted some on-farm guayule trials in southern Europe in partnership within the European based production and exploitation of alternative rubber and latex sources project (EU-PEARLS). Promising agronomic results have led to assess the profitability of a guayule commodity chain in the Mediterranean Europe area. Data on farming practices, biorefinery, costs of inputs were collected from the trials conducted in Spain and France, and from farmers and farmers’ organizations in both countries. At farm level, different cost scenarios were tested, with guayule biomass being the sole output, with annual or biennial harvests. Our results showed that, based on a nine-year field cultivation, the farmer’s breakeven point can be reached at a sale price of €147ton−1 of dry biomass (at 12tonha−1). At factory level, the biorefiner needs to sell water-extracted rubber as latex. By adding solvent extraction, it is possible to extract the remaining percentage of total rubber and the resin. In such case, the biorefiner’s profits rises to €691ton−1 of extracted rubber, making guayule cultivation profitable. Bagasse sale for electricity production or wood pellets is a bonus to be considered too. Our results showed that, in these conditions, a guayule value chain in Europe could be profitable.We extrapolated the results from our experiments to other Mediterranean countrie’s culture conditions. Our results showed that guayule cultivation would probably be more beneficial in the Southern Mediterranean countries, including Spain, than in the Northern countries (South of France). Introduction of guayule production in the Mediterranean region could contribute to improved sustainability in rural development projects, allow a new economic development of the regions, and contribute to provide a new sustainable crop alternative against the impacts of climate change such as longer and more severe drought stress.