Use Of Chemical Markers Research Articles

Analysis of fruit ripening in Theobroma cacao pod husk based on untargeted metabolomics

The pod husk of Theobroma cacao (CPH) plays an important agronomical role, as its appearance is used as indicator of ripening, guiding the farmers in the harvest process. Cacao harvesting is not a standardized practice because farmers harvest between six up to eight months from flowering, guided by pod's color and shape. The mixture of cacao beans from different ripening stages (RS), negatively affecting the quality and price of grain. A way to help the farmers in the harvest standardization could be through the use of chemical markers and visual indicators of CPH ripening. This study analyses CPH's metabolic distribution of two cacao clones, ICS95 and CCN51 at six, seven, and eight months of ripening. Untargeted metabolomics was done using HPLC-MS/MS for biomarker discovery and association to cacao ripening. The results indicated a strong metabolic differentiation of the sixth month with the rest of the months independent of the variety. Also, metabolic differences were found between cacao clones for the seventh and eighth month. We annotated five potential biochemical markers including 3-caffeoylpelargodinin 5-glucoside, indoleacetaldehyde, procyanidin A dimer, procyanidin C1, and kaempferol. We further looked for correlation between patterns of progression of our markers against quantitative indicators of CPH appearance and texture, at the same ripening stages. We also performed a functional analysis and three possible metabolic pathways: flavone and flavonol biosynthesis, flavonoid biosynthesis, and tryptophan metabolism were identified associated with stress sensing, plant development and defense respectively. We found significant and positive correlations between green color density and all metabolites. For texture, the correlations were significantly negative with all metabolites. Our results suggest that about the sixth month is appropriate for harvesting cacao in the region of Caldas, Colombia in order to avoid all the metabolic variations occurring at later stages of ripening which impact the cacao bean quality. Therefore, studying the cacao ripening process can help in the estimation of the best harvest time and contribute to the standardization of harvest practices.

Recent Advances in the Use of Chemical Markers for Tracing Wastewater Contamination in Aquatic Environment: A Review

There has been increasing research focus on the detection and occurrence of wastewater contamination in aquatic environment. Wastewater treatment plants receive effluents containing various chemical pollutants. These chemicals may not be fully removed during treatment and could potentially enter the receiving water bodies. Detection of these chemical pollutants and source identification could be a challenging research task due to the diversified chemical and functional groups, concentration levels and fate and transportation mechanisms of these pollutants in the environment. Chemical markers such as pharmaceuticals and personal care products, artificial sweeteners, fluorescent whitening agents, sterols and stanols, and nitrate and nitrogen isotopics have been widely used by most research as markers. These markers served as indicators of wastewater contamination to the receiving bodies due to their frequent usage, resistance to biodegradability and, more importantly, anthropogenic origin. These markers are commonly used in combination to identify the contaminant source of different origins. This article discusses the main chemical markers that are used to identify wastewater contamination in receiving bodies, the current trends, and approach to select suitable chemical markers.

Pea weevil damage and chemical characteristics of pea cultivars determining their resistance to Bruchus pisorum L.

Bruchus pisorum (L.) is one of the most intractable pest problems of cultivated pea in Europe. Development of resistant cultivars is very important to environmental protection and would solve this problem to a great extent. Therefore, the resistance of five spring pea cultivars was studied to B. pisorum: Glyans, Modus; Kamerton and Svit and Pleven 4 based on the weevil damage and chemical composition of seeds. The seeds were classified as three types: healthy seeds (type one), damaged seeds with parasitoid emergence holes (type two) and damaged seeds with bruchid emergence holes (type three). From visibly damaged pea seeds by pea weevil B. pisorum was isolated the parasitoid Triaspis thoracica Curtis (Hymenoptera, Braconidae). Modus, followed by Glyans was outlined as resistant cultivars against the pea weevil. They had the lowest total damaged seed degree, loss in weight of damaged seeds (type two and type three) and values of susceptibility coefficients. A strong negative relationship (r = -0.838) between the weight of type one seeds and the proportion of type three seeds was found. Cultivars with lower protein and phosphorus (P) content had a lower level of damage. The crude protein, crude fiber and P content in damaged seeds significantly or no significantly were increased as compared with the healthy seeds due to weevil damage. The P content had the highest significant influence on pea weevil infestation. Use of chemical markers for resistance to the creation of new pea cultivars can be effective method for defense and control against B. pisorum.

Variation in δ15 N and δ13 C stable isotope values in common dolphins (Delphinus spp.) worldwide, with particular emphasis on the eastern North Atlantic populations.

Distinguishing population units of small cetaceans continuously distributed in a widespread area is challenging but critical for their conservation and management. The use of chemical markers allows the investigation of foraging ecology and inter-specific variability, in order to detect population structure and niche segregation in the common dolphin (Delphinus spp.). The stable isotope ratios of carbon (δ(13)C values) and nitrogen (δ(15)N values) were measured in the bone tissue of common dolphins accidentally by-caught or stranded along the north-eastern and eastern Subtropical Atlantic Ocean, by means of continuous flow elemental analyser/isotope ratio mass spectrometry. Trophic positions were determined and compared, taking into account the local ecosystem trophic baseline for each study area. Data obtained for the study areas were qualitatively compared with those for common dolphin species/populations distributed worldwide. The δ(13)C and δ(15)N values were higher in the eastern Subtropical Atlantic as a consequence of the coexistence in the area of the common dolphin short- and long-beaked morphotypes. Individuals from the north-eastern Atlantic displayed lower δ(15)N values, reflecting dissimilarities in diet and variation in local isotopic baselines. Comparisons with other areas around the world suggest that the species is extremely adaptive and feeds at different trophic levels to adapt to local variations. Stable isotopes are a useful tool to investigate population structure and trophic niche segregation. The trophic behaviour of worldwide populations of common dolphins was fruitfully analysed and revealed substantial differences, probably reflective of both adaptive strategies of the genus and dissimilarities in the structure of the ecosystems.

Electrical conductivity and emerging contaminant as markers of surface freshwater contamination by wastewater

The use of chemical markers of undoubted anthropogenic sources for surface freshwater contamination by wastewaters was evaluated employing correlations observed between measured physico-chemical parameters as the electrical conductivity and the concentration of different emerging organic compounds. During the period from April/2011 to April/2012 spatial–temporal variations and contamination patterns of two rivers (Piraí and Jundiaí rivers), São Paulo state, Brazil were evaluated. Seven physico-chemical parameters and concentrations of different classes of emerging contaminants were determined in samples collected in seven field campaigns. The high linear correlation coefficients obtained for the compounds diclofenac (r=0.9085), propanolol (r=0.8994), ibuprofen (r=0.8720) and atenolol (r=0.7811) with electrical conductivity, also corroborated by principal component analysis (PCA), point to the potential use of these compounds as markers of investigated surface water contamination by wastewaters. Due to specific inputs, these environmental markers showed very good effectiveness for the identification and differentiation of water body contamination by discharges of treated and untreated urban sewage.

The use of chemical markers for the identification of farm escapees in feral mink populations

Variations in the contaminant burden in feral and ranch mink, resulting from differences in their diet, may permit the identification of farm escapees. However, this is only possible in the case of contaminants that accumulate to significantly different levels in the two groups of animals. The main objective of this study was to identify chemical markers whose concentrations differ between feral and ranch mink, by analyzing the accumulation of 13 chemical elements in liver and kidney samples. Total mercury levels were up to 15-fold higher in kidney, and up to 7-fold higher in liver of feral mink compared with ranch mink. The majority of feral mink samples analyzed for mercury, contained concentrations that ranged from 1 to 5 μg/g in kidney (68 %) and from 1 to 5 μg/g in liver (70 %). In comparison, the organs of ranch mink had significantly lower levels of mercury: 95 % of kidney samples had concentrations below 1 μg/g and 82 % of liver samples had concentrations below 1 μg/g. Small geographical variations in Hg levels were observed in mink from the four studied feral populations. Significant differences in Cu concentrations between ranch and feral mink were also detected, with low variation within the two groups. Less pronounced differences were recorded for other chemical elements. These data suggest that Hg and Cu may be used as chemical markers for the identification of first generation mink farm escapees.

Isotopic evidence of limited exchange between Mediterranean and eastern North Atlantic fin whales

The relationship between stocks of fin whales inhabiting the temperate eastern North Atlantic and the Mediterranean Sea is subject to controversy. The use of chemical markers facilitates an alternative insight into population structure and potential borders between stocks because the two areas present dissimilar isotopic baselines. Baleen plates, composed of inert tissue that keeps a permanent chronological record of the isotopic value of body circulating fluids, were used to investigate connectivity and boundaries between the stocks. Values were determined by continuous flow isotope ratio mass spectrometry. Stable isotopes confirm that, while the two subpopulations generally forage in well-differentiated grounds, some individuals with characteristic Atlantic values do penetrate into the Mediterranean Sea up to the northernmost latitudes of the region. As a consequence, the border between the two putative subpopulations may be not as definite as previous acoustic investigations suggested. The discriminant function obtained in this study may assist researchers to use baleen plate isotopic data to assign the origin of fin whales of uncertain provenance. This study strengthens the stock subdivision currently accepted for management and conservation while recognizes a low level of exchange between the Mediterranean and temperate eastern North Atlantic subdivisions.

VITEXIN DERIVATIVES AS CHEMICAL MARKERS IN THE DIFFERENTIATION OF THE CLOSELY RELATED SPECIES PASSIFLORA ALATA CURTIS AND PASSIFLORA QUADRANGULARIS LINN

The species of Passiflora are widely used in folk medicine as mild sedatives and tranquilizers. P. alata and P. quadrangularis are distributed throughout South America, with widespread occurrence in Brazil and Colombia. Due to the difficulty in making a botanical distinction between these species, especially in the absence of flowers and fruits, the use of chemical markers for these plants offer an alternative method of identification. This work describes the isolation and identification of the major flavonoids and saponins from the leaves of P. alata and P. quadrangularis, as well as rapid and efficient HPLC-DAD methods for comparison of these compounds in both species. Vitexin derivatives are proposed as chemical markers in the identification of P. alata and P. quadrangularis and the detection of adulterations in raw material.

Chemical markers for the quality control of herbal medicines: an overview.

Selection of chemical markers is crucial for the quality control of herbal medicines, including authentication of genuine species, harvesting the best quality raw materials, evaluation of post-harvesting handling, assessment of intermediates and finished products, and detection of harmful or toxic ingredients. Ideal chemical markers should be the therapeutic components of herbal medicines. However, for most herbal medicines, the therapeutic components have not been fully elucidated or easily monitored. Bioactive, characteristic, main, synergistic, correlative, toxic and general components may be selected. This article reviews the effective use of chemical markers in the quality control of herbal medicines including the selection criteria considering the roles and physicochemical factors which may affect the effective use of chemical markers.

Use of selected chemical markers in combination with a multiple regression model to assess the contribution of domesticated animal sources of fecal pollution in the environment

Human and animal wastes are major sources of environmental pollution. Reliable methods of identifying waste sources are necessary to specify the types and locations of measures that best prevent and mitigate pollution. This investigation demonstrates the use of chemical markers (fecal sterols and bile acids) to identify selected sources of fecal pollution in the environment. Fecal sterols and bile acids were determined for pig, horse, cow, and chicken feces (10–26 feces samples for each animal). Concentrations of major fecal sterols (coprostanol, epicoprostanol, cholesterol, cholestanol, stigmastanol, and stigmasterol) and bile acids (lithocholic acid, deoxycholic acid, cholic acid, chenodeoxycholic acid, ursodeoxycholic acid, and hyodeoxycholic acid) were determined using a gas chromatography and mass spectrometer (GC–MS) technique. The fecal sterol and bile acid concentration data were used to estimate parameters of a multiple linear regression model for fecal source identification. The regression model was calibrated using 75% of the available data validated against the remaining 25% of the data points in a jackknife process that was repeated 15 times. The regression results were very favorable in the validation data set, with an overall coefficient of determination between predicted and actual fecal source of 0.971. To check the potential of the proposed model, it was applied on a set of simulated runoff data in predicting the specific animal sources. Almost 100% accuracy was obtained between the actual and predicted fecal sources. While additional work using polluted water (as opposed to fresh fecal samples) as well as multiple pollution sources are needed, results of this study clearly indicate the potential of this model to be useful in identifying the individual sources of fecal pollution.

AFM and STM characterization of thiol and thiophene functionalized SWNTs: pitfalls in the use of chemical markers to determine the extent of sidewall functionalization in SWNTs

Thiol- and thiophene-functionalized SWNTs prepared via the reaction of a substituted amine with fluoronanotubes show similar levels of sidewall functionalization, however, the use of Au nanoparticles as chemical markers for AFM gives misleading results for substituent distribution since STM shows the thiol substituents grouped in bands while the thiophene substituents uniformly distributed along the SWNTs.

Solitary Chemosensory Cells in Mammals?

In fish, solitary chemosensory cells (SCCs) occur in the oropharynx, gills and skin and have often been found in association with taste buds. Among amphibia, a diffuse chemosensory system has been described on the ventral skin of toads, and a structural resemblance of SCCs to taste bud cells has been reported in frogs. Putative solitary chemoreceptors have been described in mammals too, at specific sites in the digestive or respiratory apparatus. In newborn rodents, a specific set of SCCs (composed of elements positive for α-gustducin, a marker of chemosensory cells) is associated with the gustatory epithelium. In conclusion, the available data suggest that a SCC system is not restricted to fish but is present in amphibia and mammals as well. At our present level of knowledge, establishing a precise homology between different species is difficult. However, the data from mammals and amphibia fully confirm previous findings in fish, and the use of chemical markers to study the diffuse chemosensory systems of vertebrates seems promising.

The use of chemical markers in the evaluation of crude oil bioconversion products, technology, and economic analysis

Experimental data gathered over the past several years show that the interactions of microorganisms with crude oils are variable and depend on the microbial species and the chemical composition of crude oils. Systematic studies of chemical mechanisms by which selected microorganisms react with crude oils have led to the identification of biochemical markers characteristic of the interactions of microbes with oils. These biomarkers belong to several groups of natural products ranging from saturate and polyaromatic hydrocarbons containing heterocyclics to organometallic compounds. Chemical marker analyses indicate that the interaction of microbes with crude oils involves multiple chemical reactions resulting from the biochemical interactions between microbes and oils. Different interactions may influence the efficiency of processes in which single or mixed microbial species are used for the oil treatment and may also suggest possible combinations of biological and chemical technologies. Further, the biochemical conversions of oils can be monitored by these chemical markers, which is particularly useful in the optimization of biochemical processing, cost efficiency, and engineering studies. Recent results from these studies will be discussed.

The spatial population dynamics of insects exploiting a patchy food resource : II. Movements between patches.

The population dynamics of ten species of phytophagous insects and seven parasitoids inhabiting the flowerheads of two herbaceous plants, Centaurea nigra and Arctium minus, were studied, and three main aspects of their ecology were examined, namely, rates of population extinction, density dependence in population changes from one generation to the next, and movements between populations. The study was based on monitoring the insect populations on more than 50 patches of each plant, scattered over 5 km2 of arable farmland and the results were used to test the relative importance of immigration and population regulation to the persistence of these populations. This paper describes the study of movements between patches of food plant. Experimentally planted new patches of plants were rapidly colonised by all species and this appeared to be unaffected by distance from a source population, up to the maximum distance of 800 m considered in the experiment. Large patches tended to be colonised more readily than small ones. Movements between plant patches were studied with the use of chemical markers (Rb, Sr, Dy and Cs) which were applied as chloride salts to individual patches, and which were translocated to the flowerheads and so to insects feeding on the seed, and to their parasitoids. Initial experiments in the laboratory showed that these elements could be readily detected by ICP (Inductively Coupled Plasma) mass spectrometry in the bodies of all species reared on potted plants sprayed with solutions containing them. Background levels of strontium were patchily high on the study area, but the other elements were naturally either absent or in very low concentrations. Four patches of each plant were marked with a different element in 1991. In 1992, samples of four species of tephritid fly and two parasitoids were collected from all patches, and analysed for the four elements. These analyses showed that individual of all species moved considerable distances, with movements of up to 2 km being commonly recorded. Estimates of rates of immigration to patches showed that movement plays an important role in the population dynamics of these insects. There was some evidence that immigration was density-dependent: it was highest when the resident populations (numbers per flowerhead) were low.