Biochemical Descriptors Research Articles

A DFT Study of Cenobamate and Its New Isomers as an Effective Medical Treatment for Epilepsy Medications

Many anti-epileptic drugs use cenobamate, a voltage-gated sodium channel blocker, to the fullest extent. This study investigates the electronic, quantum chemical, and photolytic properties of Cenobamate and its novel designed isomers. The results show that the LUMOs levels are higher than the HOMO energies. The HOMO levels are unpaired and of s-character locally around the chlorine atoms. The reactivity and stability are explained by the frontier molecular energy values and different biochemical descriptors. All isomers have smallest energy gap means with a higher reactivity for biological applications. The most frequent reaction sites are found to be the three acyl carbons in the cenobamate molecule, the chloride related to the phenyl ring, the heterocyclic ring, and the carbonyl oxygen and nitrogen in the ester amide group. The novel isomers have high ability to interact with species, and this takes place either in clinical use or under clinical trials. The isomers are soft compounds, and can easily interact with big soft molecules such as DNA.

Performance of Radiological and Biochemical Biomarkers in Predicting Radio-Symptomatic Knee Osteoarthritis Progression.

Imaging biomarkers permit improved approaches to identify the most at-risk patients encountering knee osteoarthritis (KOA) progression. This study aimed to investigate the utility of trabecular bone texture (TBT) extracted from plain radiographs, associated with a set of clinical, biochemical, and radiographic data, as a predictor of long-term radiographic KOA progression. We used data from the Foundation for the National Institutes of Health (FNIH) Biomarkers Consortium dataset. The reference model made use of baseline TBT parameters adjusted for clinical covariates and radiological scores. Several models based on a combination of baseline and 24-month TBT variations (TBT∆TBT) were developed using logistic regression and compared to those based on baseline-only TBT parameters. All models were adjusted for baseline clinical covariates, radiological scores, and biochemical descriptors. The best overall performances for the prediction of radio-symptomatic, radiographic, and symptomatic progression were achieved using TBT∆TBT parameters solely, with area under the ROC curve values of 0.658 (95% CI: 0.612-0.705), 0.752 (95% CI: 0.700-0.804), and 0.698 (95% CI: 0.641-0.756), respectively. Adding biochemical markers did not significantly improve the performance of the TBT∆TBT-based model. Additionally, when TBT values were taken from the entire subchondral bone rather than just the medial, lateral, or central compartments, better results were obtained.

Undisturbed Posidonia oceanica meadows maintain the epiphytic bacterial community in different environments

Seagrasses harbour different and rich epiphytic bacterial communities. These microbes may establish intimate and symbiotic relationships with the seagrass plants and change according to host species, environmental conditions, and/or ecophysiological status of their seagrass host. Although Posidonia oceanica is one of the most studied seagrasses in the world, and bacteria associated with seagrasses have been studied for over a decade, P. oceanica’s microbiome remains hitherto little explored. Here, we applied 16S rRNA amplicon sequencing to explore the microbiome associated with the leaves of P. oceanica growing in two geomorphologically different meadows (e.g. depth, substrate, and turbidity) within the Limassol Bay (Cyprus). The morphometric (leaf area, meadow density) and biochemical (pigments, total phenols) descriptors highlighted the healthy conditions of both meadows. The leaf-associated bacterial communities showed similar structure and composition in the two sites; core microbiota members were dominated by bacteria belonging to the Thalassospiraceae, Microtrichaceae, Enterobacteriaceae, Saprospiraceae, and Hyphomonadaceae families. This analogy, even under different geomorphological conditions, suggest that in the absence of disturbances, P. oceanica maintains characteristic-associated bacterial communities. This study provides a baseline for the knowledge of the P. oceanica microbiome and further supports its use as a putative seagrass descriptor.

Unravelling and Quantifying the Biophysical– Biochemical Descriptors Governing Protein Thermostability by Machine Learning

AbstractAnalysis of protein thermostability is vital in protein science to aid the understanding of evolutionary aspects of organic life as well as in protein engineering for modern day industrial applications. In the present study, supervised machine learning (ML) algorithms are employed to unravel potential patterns behind protein thermostability. This computational analysis conclusively shows inverse gamma turns, VIII turns, and the propensity of cysteine (Cys) to be the most important biophysical–biochemical attributes responsible for protein thermostability. From the propensity analysis of amino acids, polar residues, specifically glutamine (Gln) and serine (Ser), and charged residues, specifically glutamic acid (Glu) and lysine (Lys), are found to favor the enhancement of protein thermostability. The study demonstrates the feasibility of assigning quantifiable descriptors of thermostability which is expected to aid protein engineering.

Características químicas y fitoquímicas como descriptores bioquímicos de la diversidad en semillas de cacao de una colección del sur de Ecuador

The objective of this work was to determine the content of some chemical and phytochemical characteristics, in seeds of 60 cocoa trees from a collection in southern Ecuador; to identify their potential as biochemical descriptors. Brix degrees (ºBrix), moisture (MO), lipids (LI), total phenols (TP), and antioxidant activity (AA) were determined. Statistical analysis indicated that there was low variability in ºBrix, MO and LI; and high variability in TP and AA. ºBrix was distributed in five classes; MO, LI, and AA in four and TP in three; several trees presented high contents and close to the standards: ºBrix (16-21.34 ºBrix), MO (7-7.90%), LI (50.03- 60.71%), TP (5.05-14.46 mg GAE.g-1) and AA (92.48-275.16 mg TE.g-1). A significant correlation (p<0.01) was found between LI and TP (r=-0.334), and between TP and AA (r=0.802). The TP and AA variables showed a high positive correlation, while LI and TP a low and negative. The accumulated variance was 64.54%, represented by TP and AA. It is concluded that the variability was influenced by the genotype and was high in TP, and AA. TP and AA constituted excellent biochemical descriptors of diversity in cocoa seeds. The trees FCA58, FCA59, FCA48, FCA45, and FCA46 presented the highest values of TP and AA, so they were promising as cultivars, for plant breeding and industry, among others.

Pomegranate morpho-chemodiversity: computational investigations based on in-vivo and in-vitro screening

Pomegranate tree is cultivated since ancient times in Morocco, where a high genetic diversity is hosted mainly in traditional agroecosystems. Over the past decade, it regained importance through extension of cultivated area, but remains thus far little valued. To date, its genetic variability and chemodiversity have gone unheeded for many reasons, some of which are related to previous agricultural strategies. In this context, the present study aimed to screen an ex-situ collection of seven local cultivars and seven exotic varieties with regard to 50 fruit morphometric and biochemical descriptors. The results showed statistically significant variability within accessions (p < 0.01), based on all aforementioned traits, except for seed weight, with coefficients of variation greater than 49%. This indicated a high level of phenotypic diversity among the studied genetic pool. The 3D scatter plot built based on the principal component analysis displayed an interesting discrimination with regard to the genotypes' geographic origins with a total variance of about 50%. According to morphometric based-heatmap, four main clusters were identified distinguishing the typicality of some local cultivars compared to exotic varieties, mainly ‘Sefri’, ‘Bzou’, ‘Chioukhi’ and ‘Djeibi’. Traits having the highest impact on discrimination between accessions were, by order of importance, fruit weight and its dimensions, juice yield, aril yield, single aril diameter, soluble sugars (glucose and fructose) along with contents in some organic acids, including citric, palmitic, linoleic and malic acids. Potential statistically significant correlations were spotted through bi-dimensional heatmap analysis, particularly between the fruit size, shape and peel traits along with some biochemical attributes. As many areas of the species chemodiversity and functional properties are still needed to be investigated further, the results of the present study are of great interest for the species valorization and for breeding programs.

Elective affinities or random choice within the seagrass holobiont? The case of the native Posidonia oceanica (L.) Delile and the exotic Halophila stipulacea (Forssk.) Asch. from the same site (Limassol, Cyprus)

Seagrasses and associated microbial communities constitute a functional unit (holobiont) which responds as a whole to environmental changes. However, it is still unclear how the microbial colonizers are selected. In this study we compared the epiphytic microbial communities associated with Posidonia oceanica and Halophila stipulacea, Mediterranean native and exotic seagrass species, respectively, growing side by side in monospecific patches within the port of Limassol (Cyprus, Eastern Mediterranean Sea). To evaluate whether the environment rather than the host species and/or its physiological condition play a role in shaping the seagrass epiphytic microbial community, the environmental microbial communities (seawater and sediment) and seagrass associated ones were determined by using 16S rRNA gene amplicon sequencing. Plant ecological status was evaluated by morphological (biometry), structural (density) and biochemical (pigment/phenol content) descriptors. In both species, leaf associated microbial communities are clearly similar to seawater microbes; conversely, microbes associated with H. stipulacea roots/rhizomes differ from the microbial communities in surrounding sediment. In both seagrasses, Pseudomonadaceae was the most abundant family on leaves, but each species harboured unique microbial families. To our best knowledge, this is the first study on these two neighbouring seagrass species, coupling plant ecological status with associated microbial communities. Results demonstrated that each seagrass responded differently to the same environmental conditions and selected different epiphytic microbial communities, supporting their putative use as ecological indicators.

Characterization of cashew: A review with reference to morphological, biochemical and molecular descriptors

Characterization of cashew: A review with reference to morphological, biochemical and molecular descriptors

Pathological and biochemical descriptors of Ralstonia solanacearum of tomato (Solanum lycopersicum) in Tanzania

An experiment was conducted to identify bacterial wilt disease-causing isolates of Ralstonia solanacearum (Smith) in Tanzania. The pathological and biochemical descriptors were used to determine the virulence and biovars of 40 bacterial isolates originating from 200 wilted tomato (Solanum lycopersicum L.) stems collected from the main agro ecological zones of Tanzania. Results revealed that 53% of the investigated isolates were pathogenic, whereas 90% of isolates belonged to biovar 3 and the rest (10%) were biovar 2. Biovar 3 was present in all of the surveyed agroecological zones, whereas biovar2 prevailed in Southern zone only and is reported for the first time in Tanzania. This is an alert for plant health officers to implement standard phytosanitary measures in preventing new introduction and spread of Ralstonia to uninfected locations. Descriptors adopted successfully identified biovars of Ralstonia, thus can be integrated with other diagnosis tools to manage bacterial wilt disease.

Physiological damages of Sargassum cymosum and Hypnea pseudomusciformis exposed to trace metals from mining tailing.

The damages of Mariana's mining mud in the physiology of the brown algae Sargassum cymosum and its main epiphytic, the red algae Hypnea pseudomusciformis, were evaluated by controlled essays. Seaweeds were exposed to presence or absence of mud, isolated or in biological association, for 5 and 15 days. Measured parameters were growth rates, biochemical descriptors, and the chemical investigation of concentration and metal profile of the mud dissolved in seawater. Results showed that the highest values for metals were Al > Fe > Mn > Zn in both exposure periods. The mud also affected the growth rate with lethality in both isolated and associative treatments with H. pseudomusciformis after 15 days. According to our redundancy analysis (RDA), the profile and concentration of all metallic elements can induce different physiological responses of the organisms. We were able to observe a higher physiological adaptive ability of S. cymosum against the long-term presence of metals by the synthesis of phenolic compounds, while the deviation of metabolic routes in H. pseudomusciformis can be addressed as the main responsible for its lethality. Moreover, the presence of Hypnea in associative treatments reduces Sargassum's detoxification ability. The present results reinforce the importance of biological interaction studies in a context of physiological resilience against mining mud pollution and mutual influences of species over the individual ability to avoid oxidative stress.

New Brazilian lines of Habanero pepper (Capsicum chinense): Morpho-agronomic and biochemical characterization in different environments

Habanero pepper is known for the diversity of its morphological characteristics and its biochemical attributes. The growth of international demand for this type of pepper is an additional opportunity for Brazilian farmers and processing industries. In order to meet this demand, it is necessary to develop new cultivars with high fruit quality and adaptation to the Brazilian growing conditions. The objective of this study was to carry out a morpho-agronomic and biochemical characterization of new lines of Habanero pepper cultivated in different environments, and to investigate the genotype x environment interaction, aiming to provide subsidies for the registration process of the new cultivars, and their subsequent release. Three advanced endogamic lines and two commercial cultivars, as control, were grown in three different growing environments, two in open field and one in protected environment. The characterization of the lines was based on nine morpho-agronomic and nine biochemical descriptors and field-incidence of the five main virus diseases. The three new lines presented important and desirable characteristics such as high yield, adequate plant size (100.0–150.0 cm) and superior quality of fruits in protected environment (CNPH 15,744); open field cultivation potential with high yield (35.0 to 40.0 t ha−1; CNPH 15,749 and CNPH 15,740); and superiority for fruit characteristics, lower total titratable acidity (15–22 %) and absence of Potato virus Y (CNPH 15,740). CNPH 15,740, CNPH 15,744 and CNPH 15,749 lines present the potential to be submitted to the cultivar registration process, mandatory in the Brazilian agricultural system, and released as new Habanero pepper cultivars developed in and adapted to Brazil, increasing the options for pepper value chain and for intermediate and final consumers. CNPH 15,744 presented unique sensory qualities for a C. chinense Habanero.

Biochemical descriptors: importance of the genetic divergence study in peppers

ABSTRACT The genetic diversity of pepper genotypes is usually evaluated based on morphological and molecular descriptors. However, studies using biochemical descriptors of peppers are still incipient. Thus, the objective of this study was identify biochemical descriptors of Capsicum spp. with antioxidant action, most responsive to the selection of superior genotypes, and evaluate the correlation between concentrations of the parameters using principal components analysis. The experiment was conducted in the city of Cáceres, southwest Mato Grosso, Brazil. Seventy-eight pepper accessions from the Active Germplasm Bank of UNEMAT were planted in randomized block design. The harvested fruits were immersed in liquid nitrogen for two minutes, and the following biochemical analyses were performed: titratable acidity, ascorbic acid, total phenols, flavonoids, anthocyanins, carotenoids, chlorophyll a, chlorophyll b, and antioxidant activity. Biochemical descriptors that best estimated the genetic variability of the accessions were flavonoids, total phenols, chlorophyll a, and ascorbic acid. Chlorophyll a and chlorophyll b were the compounds that showed the highest degree of correlation. Except chlorophyll a with ascorbic acid, all other vectors showed correlation ranging from moderate to strong.

Intellectual property rights (IPRs) for plant breeders: a review on theoretical framework and employment of DNA-based varietal authentication for claiming IPR

Plant patents (PPs) and Plant Breeders’ Rights (PBR) are two forms of Intellectual Property Rights (IPRs) granted to improved novel crop varieties. The government of the state of authority issues PPs and PBR after confirming the uniqueness of varietal identity. The uniqueness relies on distinctiveness, uniformity, and stability of the new variety. Morphological, physiological and biochemical descriptors are less capable in varietal discrimination to obtain IPR in the presence of large number of closely related varieties as the reference collections, but advanced molecular tools such as DNA fingerprinting and sequencing have high potentials to detect the uniqueness. DNA fingerprinting and sequencing have identified varietal identities of many crops such as rice, apple, wheat, and soybean revealing the potential of the successful use of molecular descriptors in granting patents or PBR. The novelty verification is the first step in the process of allowing patents or PBRs. The patent or plant variety protection office requires an application from the breeder that includes all the details of the plant variety fulfilling all statutory requirements to grant varietal ownership via a patent certificate or a plant variety protection certificate. Currently, Sri Lanka has no developed system of IPRs to allow PBR or patents for improved crop varieties. The efforts made by breeders in developing novel varieties can be justified and appreciated by granting plant varietal ownerships. For this purpose, molecular descriptors must be used instead of inefficient morphological, physiological and biochemical characters to avoid ambiguities and to clearly define the inventor of a particular variety.

GENOTYPIC VARIABILITY OF PEANUT LINES IN RESPONSE TO WATER STRESS, BASED ON BIOCHEMICAL DESCRIPTORS

ABSTRACT Seven biochemical descriptors were used to estimate the genotypic variability of peanut in response to moderate water stress. Six genotypes, constituted by four lines and two cultivars, were grown in pots, each containing two plants. At 15 days after emergence (DAE), the treatment differentiation was carried out: Control-plants maintained with daily watering, and Stress-plants submitted to water stress by complete suspension of watering for 15 days. The experimental design was completely randomized with factorial scheme 6 x 2 (genotype x water treatments), with five replications. The biochemical variables evaluated were: catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), free proline, total carbohydrates, soluble proteins, and amino acids. Results obtained by biochemical analysis and estimation of genotypic variability indicated that proline is the most appropriate descriptor for selecting genotypes tolerant to water stress, which led to identification of L81V and L108V as promising lines for drought tolerance breeding program.

Assessing the ecological status of seagrasses using morphology, biochemical descriptors and microbial community analyses. A study in Halophila stipulacea (Forsk.) Aschers meadows in the northern Red Sea

Seagrasses are one of the most valuable marine ecosystems on earth, yet they are declining worldwide at alarming rates. With most of seagrass monitoring based on long term responses to environmental pressures, there is growing interest in developing alternative diagnostic tools that more effectively identify changes in seagrass ecological status at an early stage. Besides morphological indicators, functional and biochemical descriptors may provide a good understanding of plant's responses to environmental changes. Moreover, the epiphytic microbial communities of seagrasses may also shift in response to changes in environmental conditions, although these have been seldom used as a descriptor of environmental change. In this study three Halophila stipulacea (Forsk.) Aschers meadows, found in the Gulf of Aqaba (northern Red Sea), were characterized using an integrated approach to highlight possible differences in the meadows ecological status. Plant descriptors, including leaves morphometrics (leaf size, leaf number/plant, leaves with lost apex), photosynthetic pigments (Chlorophylls, Carotenoids) and total phenols contents, were investigated and coupled with the plants’ epiphytic microbial community structure and composition, studied using pyrosequencing. The entire suite of descriptors highlighted differences among the meadows ecological status based on changes in plants’ morphology and biochemistry, and their associated microbial communities, in response to the different environmental conditions (water column turbidity, seawater and sediment nutrients) and the geomorphological features (bottom slope, granulometry) of the stations. Leaf morphology and photosynthetic pigment content were modulated in H. stipulacea in response to light availability and hydrodynamics in the Gulf of Aqaba. The highest leaf surface area and photosynthetic pigment contents were observed at the lowest irradiance and hydrodynamics/granulometry among stations. Total phenol content showed differences among stations with increasing concentrations from north to south. The microbial communities showed differences among stations and plant compartments, with high incidence of Gammaproteobacteria and Bacteroidetes in light limiting conditions, while Cyanobacteria and Rhodobacteraceae thrived in conditions of high light availability and hydrodynamics. The mutual response of the seagrass plants and the microbial communities provided evidence of their functional relationship, which undoubtedly needs further investigation. To the best of our knowledge, this is the first time that such descriptors have been used in an integrated approach. We provide evidence of their effectiveness in discriminating seagrass ecological status, even at small spatial scales. This work constitutes a new approach to the assessment of seagrasses and a stepping stone in the application of microbial communities as a putative marker in a changing environment.

Evaluation of metal enrichment and trophic status on the basis of biogeochemical analysis of shelf sediments of the southeastern Arabian Sea, India

The present study investigated the distribution of environmentally relevant metals and organic matter in the shelf sediments of the southeastern Arabian Sea using biogeochemical proxies for the assessment of environmental quality and trophic status. The distribution of metals in the study site followed the order: Fe>Mg>Pb>Ni>Mn>Co>Cu>Zn>Cd. High biological productivity associated with upwelling leads to significant accumulation of Cd higher than crustal abundance in the shelf region. The enrichment factor (EF) of metals demonstrate enrichment of Pb and Co which suggests the anthropogenic influence and not redox conditions. The sediment quality guidelines (SQG) in comparison with metal concentration revealed adverse effects, possibly occurring in marine benthic species. The spatial trend of metal enrichment along transects is appreciably controlled by the adsorption to fine grained sediments. The multivariate statistical analyses, such as correlations and principal component analysis (PCA) clearly indicated the control of texture, association of clay minerals in the degree of trace metal (Cd, Pb, Ni and Co) contamination from anthropogenic as well as natural sources. Low levels of Zn, preferably display scavenging by Fe/Mn metal oxides. Biochemical descriptors in sediments indicated meso-oligotrophic conditions prevailing in the summer monsoon. The ratios among various biogeochemical parameters such as total organic carbon/total nitrogen (TOC/TN<10), protein/carbohydrate (PRT/CHO<1) displayed that the organic matter deposited of marine origin which is relatively old with potentially low nutritional value. The close relationship between biochemical components and phytopigments suggest a major contribution of autochthonous phytodetritus derived organic matter. The study provides important information about sediment biogeochemistry and metal contamination from a potential fishery zone of Indian exclusive economic zone.

A multidisciplinary approach to enhance the conservation and use of hazelnut Corylus avellana L. genetic resources

During recent years, there has been increasing awareness of the importance of adopting a holistic view of biodiversity, including agricultural biodiversity, conservation for sustainable utilization and development. These principles have been underlined in the Convention on Biological Diversity and the European efficiency resources towards 2050. Thus critical issues are now to understand the distribution and extent of genetic diversity available to breeders and stakeholders, the kind and range of characterization, how to face the problem of continuous expanding of germplasm to be conserved. Focusing on the case study of hazelnut which is a crop of great importance for European countries, the paper describes a resourceful strategy for re-organizing and sharing hazelnut genetic resources through an upgrading of knowledge on their value and uses. The paper summarizes the progresses so far and provides a ‘launching pad’ for future researches. The brief review discusses also the recent progresses in recovery, characterization conservation and uses of European hazelnut germplasm achieved by 068 AGRI GEN RES SAFENUT which was one of the 17 Action financed by the European Commission—Directorate General for Agriculture and Rural Development. The current status on the morphological and molecular characterization of the in situ and ex situ of the most important European collections, the rescue and preservation of new accessions recovered on farm were discussed underling critical aspects. A better understanding of hazelnut genetic diversity and its distribution is essential for its conservation and use as well as the harmonization of the morphological and biochemical descriptors. The importance of traditional knowledge is also considered as integrated part of the multidisciplinary approach useful to rationalize genetic resources maintained in the collections. Thus improving the characterization on cultivated and wild forms through the development of a core collection, is the further step to achieve a more effective management and use of European nuts germplasm.

Determination of biological characteristics of Tunisian Artemia salina populations

In this study, Artemia salina cysts collected from four Tunisian hypersaline environments were characterized using biometrical, biological and biochemical descriptors. Biometrical analysis revealed that the mean diameter value ranged from 220.25 to 237.76 μm, for the untreated cysts, from 199 to 224.52 μm for decapsulated cysts and that the chorion thickness ranged from 6.62 to 10.58 μm. 48 h after hatching, Artemia from Sebkha El Meleh, Sebha Moknine, Sfax saltworks and Sahline saltworks presented a hatching percentage of 52.7%, 53.75%, 70.16% and 43.74%, respectively. The length of the freshly hatched instar I nauplii varied from 429 to 449.34 μm. The fatty acids profile showed that the n-3 series was strongly dominant in the samples collected from Sebkha Moknine and Sfax saltworks, representing a percentage ranging from 17.92% to 22.45% of the total fatty acids. The data collected in this study can be useful to add new information on biological and biochemical characterization of Artemia strains present in Tunisia. On the basis of fatty acid profile, the Artemia strains collected from Sahline saltworks, Sfax saltworks and Sebkha El Meleh can be as classified as “marine” type, and that from Sebha of Moknine as “freshwater” type.

Benthic trophic status of sediments in a metropolitan area (Rio de la Plata estuary): Linkages with natural and human pressures

We evaluated the benthic trophic status of the Montevideo coastal zone-Rio de la Plata estuary using the quantity and the biochemical composition of sedimentary organic matter as synthetic descriptors. The spatio-temporal patterns in the biochemical composition of sedimentary organic matter were related to the presence of some natural and human pressures. Biochemical features were analyzed correlatively with the type and proximity of certain impacts to investigate the usefulness of this biochemical approach for assessing the levels of natural and anthropogenic perturbations. Chlorophyll-a, phaeopigment and the biopolymeric carbon concentrations were similar to those reported in very productive, eutrophic and anthropised estuarine areas. Total proteins (PRT) and lipids (LIP) showed the highest concentrations in the inner portion of Montevideo Bay, decreasing towards the nearby coastal areas of Punta Carretas and Punta Yeguas. Total carbohydrates (CHO) presented the lowest values in the outer stations of Montevideo Bay, but similar and higher concentrations were recorded in the inner stations of the bay and the adjacent coastal zones. PRT:CHO ratios >1 were always observed for the inner stations of Montevideo Bay thus suggesting intense detritus mineralization and an increment in their protein content due to bacterial activity. The biopolymeric carbon showed the same spatial trend observed for PRT, LPD and the PRT: CHO ratios with highest concentrations in the inner bay than in Pta. Carretas and Pta. Yeguas. Elevated contributions of PRT and LIP in the inner Montevideo Bay may be associated with anthropogenic inputs of organic matter such as sewage, food industry and petroleum hydrocarbons. Conversely, high CHO contributions in the nearby coastal areas of Pta. Carretas and Pta. Yeguas seemed to be related to autochthonous primary production and CHO temporal variability with natural oscillations in the productivity of the system. Biochemical composition of organic matter indicates hypertrophic conditions and poor environmental quality in the sediments of the inner stations of Montevideo Bay due to strongest human impact. However, biochemical descriptors showed a relative improvement of the benthic trophic status in the external coastal areas subjected to moderate levels of anthropogenic pressure. This study confirmed the utility of this biochemical approach to establish zones with distinct benthic trophic status associated to different degrees of natural and human pressures. Nevertheless, our results suggest that threshold levels for PRT, BPC and the algal contribution to the BPC that properly reflect hypertrophic conditions should be further investigated.

Influence of the organic matter composition on benthic oxygen demand in the Rhône River prodelta (NW Mediterranean Sea)

Measurements of diffusive (DOU) and total (TOU) sediment oxygen uptakes, oxygen penetration depth, porosity, OC, TN, carbohydrate, lipid, amino acid, chlorophyll a and pheophytin a concentrations were assessed in surface sediments at 9 stations located in the Rhône River prodelta and the adjacent continental shelf during April 2007 (a period characterized by low flow and discharge regimes). Our results show that sedimentary organics in the Rhône River prodelta were mainly fueled by a single source of OM, namely continental inputs. Those inputs were relatively labile and decreased following an inshore–offshore gradient. The descriptors of sedimentary organics mostly resulted from dilution and degradation processes affecting OM during its transfer from the mouth of the Rhône River. TOU/DOU ratios were close to one, with a slight increase at offshore stations. This is coherent with the limitation of bioirrigation in response to organic enrichment. DOU correlated best with bulk quantitative descriptors of sedimentary organics, which probably resulted from the overall correlation between all biochemical descriptors linked with the predominance of a single source of organic matter in the whole studied area. Nevertheless, an influence of Chl a and Pheo a contents on oxygen consumptions, possibly due to freshwater or/and marine primary production, is not to be excluded. These small fractions (<0.08‰ to total OM) could then be responsible for the oxygen consumption, even if not visible in classical measurements as δ 13C or C/N.