Contribution Of Different Functional Groups Research Articles

Contributions of Different Functional Groups to Particles in Electrophoretic Display

Electrophoretic display (EPD) has excellent research potential because of its ultra-low power consumption and friendliness to the eyes. To obtain efficient electrophoretic inks, researchers need to understand the charging mechanism of electrophoretic particles. In this work, several silane coupling agents with similar main chains but different functional groups on the side chains were used to investigate the effects of different functional groups on the charging properties of the electrophoresis particles. The results showed that silane coupling agents containing amino groups resulted in the most positively charged particles, and those containing carboxyl groups resulted in the most negatively charged particles. More importantly, after introducing many additional amino groups by grafting, it was found that the charge on the particle surface was only slightly elevated, indicating that the polymer layer grafted on the particle surface would cover the functional groups inside and hinder the acid-base interactions between the functional groups in the inner layer and the charge control agent. The findings of these results may contribute to the precise design of materials for electrophoretic display.

Role Evaluation of Active Groups in Lignin on UV-Shielding Performance

The contribution of the active groups in lignin to ultraviolet (UV)-shielding performance still remains unclear. In this study, we employed 16 lignin model compounds and theoretical calculations to ascertain the contribution of different functional groups to UV-shielding performance. These results showed that the order of UV-shielding performance on functional groups was −C═C–CHO > −C═C–COOH > −C═C–CH2OH > −C═C > quinone > −COOH > −OCH3 ≈ −OH. Moreover, the synergism between the para-substituted electron-donating group −OH and the electron-withdrawing group allyl on the aromatic ring played a major role in UV-shielding performance of lignin models, whereas the additive effect of meta/ortho-substituted −OCH3 played a secondary role. Furthermore, we found that the hydrophile–lipophile balance (HLB) value of lignin models also greatly affected the sunscreen protection factor (SPF) of lignin model-based sunscreens. A closer HLB value of lignin to 8.89 corresponded with a higher SPF of the lignin model-based sunscreen. The commercial photoprotective ingredient ethylhexyl methoxycinnamate (EHMC) and lignin models had a synergistic effect on UV-shielding performance caused by the π–π stacking interaction between the parallel-displaced stacked aromatic rings of lignin models and EHMC. Additionally, the UV irradiation test showed that these sunscreens prepared using lignin models and EHMC exhibited good photostability.

Contribution of legume and non-legume trees to litter dynamics and C-N-P inputs in a secondary seasonally dry tropical forest

Many studies have investigated nutrient cycling in seasonally dry tropical forests, but few have assessed the contribution of different functional groups to these processes. Here, we investigated general litter dynamics patterns and the contribution of legume and non-legume trees to litter dynamics and carbon (C), nitrogen (N), and phosphorus (P) inputs in a fragment of secondary seasonally dry tropical forest after half a century of forest succession in the Atlantic Forest biome in Brazil. Between 2016 and 2017, we quantified litterfall production, canopy cover, forest floor, and soil C and N storage in 11 permanent plots distributed in the fragment. Vegetation identity and structure had been previously assessed. We quantified the seasonal inputs of leaf litter and C, N, and P separately for each functional group (legume and non-legume tree species). We also analyzed the correlations between the variables measured for each functional group with the variables measured at the plot level. Litter dynamics and nutrient input were affected by climate and functional group. Litterfall production during the two driest months was three times higher than during the other periods of the year, suggesting that species synchronicity is likely to minimize drought-related damage on trees. Legume trees had twice the basal area attained by non-legume trees, but while legumes were larger, non-legumes were more abundant and dominant in the smaller diameter class. Legumes deposited twice as much N during the driest period of the year as non-legumes. Although leaf litter, C, and P inputs by legumes were generally higher than those of non-legumes, these differences during the dry season were not statistically significant. We also found that the legume variables correlated better with the plot-level variables, compared to the non-legume functional group. Our results also indicated potential effects of the leaf litter and nutrient inputs by the legume functional group on the decomposition constant and, consequently, on the time of forest floor decomposition. Further studies should assess the role of different functional groups in litter dynamics and nutrient inputs in seasonally dry tropical forests.

A study on the utilization of rice husk as a biosorbent material for Cr (VI) removal from industrial effluent


 
 
 
 Purpose: To study Cr (VI) removal from waste water using chromium-resistant bacterial strains in combination with rice husk.
 Methods: Two strains of Exiguobacterium sp. resistant to chromium (VI) were applied in the present work. Rice husk (RH) was used as an agricultural waste for Cr (VI) removal. The elimination of Cr from the husk was chemically facilitated using hydrochloric, sulphuric and citric acids, as well as formaldehyde and potassium dihydrogen phosphate Investigation of optimum physical factors such as pH, temperature, shaking speed and biomass concentration on Cr (VI) removal was carried out using citric acid-processed rice husk alone, and in combination of bacterial strains. Fourier transform infra-red (FTIR) spectroscopy was performed to determine the contributions of different functional groups involved in Cr (VI) binding. Scanning electron microscopy (SEM) of treated and untreated RH was also performed.
 Results: Citric acid-processed RH was most effective in the removal of chromate (97.3 %). The two bacterial strains combined with rice husk proved highly efficient in Cr (VI) removal from sterile and non-sterile industrial effluents. FTIR spectra showed the involvement of esters, amines and aliphatic functional groups in Cr (VI) binding, while SEM displayed the damaging effects of Cr (VI) on the surface of RH; however, bacterial inoculation minimized the damage.
 Conclusion: Exopolysaccharides from Exiguobacterium strains and citric acid-processed rice husk demonstrated high efficiency for Cr (VI) removal. Hence, RH with these bacterial strains are potential biosorbents for control of heavy metal contamination arising from industrial effluents.
 
 
 

Thermal neutron cross sections of amino acids from average contributions of functional groups

The experimental thermal neutron cross sections of the 20 proteinogenic amino acids have been measured over the incident-neutron energy range spanning from 1 meV to 10 keV and data have been interpreted using the multi-phonon expansion based on first-principles calculations. The scattering cross section, dominated by the incoherent inelastic contribution from the hydrogen atoms, can be rationalised in terms of the average contributions of different functional groups, thus neglecting their correlation. These results can be used for modelling the total neutron cross sections of complex organic systems like proteins, muscles, or human tissues from a limited number of starting input functions. This simplification is of crucial importance for fine-tuning of transport simulations used in medical applications, including boron neutron capture therapy as well as secondary neutrons-emission induced during proton therapy. Moreover, the parametrized neutron cross sections allow a better treatment of neutron scattering experiments, providing detailed sample self-attenuation corrections for a variety of biological and soft-matter systems.

Species diversity, composition, structure and management in agroforestry systems: the case of Kachabira district, Southern Ethiopia

Agroforestry is increasingly being identified as an integrated land use enhancing plant diversity while reducing habitat loss and fragmentation. This paper examined species diversity, composition, structure and management in agroforestry systems. Two Kebeles (Kachabira and Mesafe) were purposively selected for this study. Then, farmers who dominantly practiced agroforestry practices such as home garden, parkland and live fence were stratified based on wealth categories. Ten percent of the sample households were randomly selected from each wealth category. Accordingly, a total of 83 households were selected. Inventories of plant species were done by sampling one plot of each farm management type. A total of 59 plant species, belonging to 56 genera and 36 families were recorded across the home gardens, parklands and live fences in the study area. Among the plant species, trees constituted 42%, shrubs 27%, herbs 29% and climber 2%. From recorded plant species, 66% were native and the remainders 34% were introduced species. From the native species recorded in this study, Lippia adoensis and Millettia ferruginea were endemic to Ethiopia. The mean Shannon diversity index of rich, medium and poor households in the three different agroforestry practices were 1.75, 1.57 and 1.62 in home garden, 0.36, 0.30 and 0.49 in parkland and 0.84, 0.99 and 1.00 in live fence respectively. The largest tree basal area was recorded in the live fence (14.7 m2ha-1), followed by home garden and parkland. The study revealed that agroforestry plays an important role in the conservation of biodiversity, and also by providing food, income and a wide range of other products such as fuel wood, construction material, fodder, spices and medicinal plants. Farm household landholding size, species preference and management found to be the most important influencing factors that affect the diversity of plant species. Further detailed study of explicit examining of the factors such as socio-ecological effects that determine species diversity and the contribution of different functional groups to livelihood is needed to fully understand the agroforestry system.

Contributions of Different Functional Groups to Contact Electrification of Polymers.

Polymers are commonly used to fabricate triboelectric nanogenerators (TENGs). Here, several polymer films with similar main chains but different functional groups on the side chain are employed to clarify the contributions of each functional group to contact electrification (CE). The results show that the electron-withdrawing (EW) ability and density of these functional groups on the main chain can determine both the polarity and density of CE-induced surface charges. Similar results are obtained for CE in both the polymer-polymer and polymer-liquid modes. A theoretical mechanism involving electron cloud overlap is proposed to explain all of these results. More importantly, the unsaturated groups on poly(tetrafluoroethylene) molecular chain are proved to have a much stronger EW ability than the saturated groups. The density of these unsaturated groups can be increased using a sputtering technique, suggesting that this is a facile and effective method of enhancing the performance of TENGs. These results clarify the correlation between the molecular structure and macroscopic electrification behavior of polymers.

Exploring water-soluble organic aerosols structures in urban atmosphere using advanced solid-state 13C NMR spectroscopy

Abstract Water-soluble organic matter (WSOM) in air particles has profound effects on climate and human health. At the heart of this environmental significance of WSOM lies a complex set of compounds, of which a major fraction still often remains undeciphered. Yet, not all environmental problems require delving into the molecular-level identification of WSOM constituents. Understanding the contribution of different functional groups to whole aerosol WSOM composition offers a highly important structural dataset that enables a better representation of WSOM in climate studies. For the first time, advanced solid-state 13C nuclear magnetic resonance (NMR) techniques, including nearly quantitative 13C multiple cross polarization/magic angle spinning (multiCP/MAS), multiCP/MAS with dipolar dephasing, multiCP/MAS with 13C chemical shift anisotropy filter, and two-dimensional 1H–13C heteronuclear correlation (2D HETCOR), are applied to acquire an accurate quantitative structural description of whole aerosol WSOM collected in an urban atmosphere. Two urban aerosol WSOM samples collected in two short periods of time, under different wintry weather conditions, were investigated. NMR data successfully pinpointed the variability of whole aerosol WSOM composition, allowing to suggest source-specific structural characteristics for each sample in two short periods of time. A new structural model of urban aerosol WSOM was build based on this compositional data, showing the presence of three independent classes of compounds that vary both in content and molecular diversity within short periods of time: heteroatom-rich aliphatic (either chain or branched), carbohydrate-like moieties, and highly substituted aromatic units. These findings establish advanced solid-state NMR as a promising tool for probing the chemical structures of inhomogeneous aerosol WSOM in rapidly changing atmospheric conditions, allowing to resolve discrepancies between modeled and measured aerosol WSOM.

Carbonate budgets as indicators of functional reef “health”: A critical review of data underpinning census-based methods and current knowledge gaps

• Calcium carbonate budgets as indicators for reef health are understudied. • Geographic gaps exist in the Coral Triangle and Southwestern Pacific. • Further studies are necessary across reef zones and depth, and over time. • Paucity of supporting data on calcification and erosion constrains budget estimates. • Future research to increase spatial coverage and study environmental change impacts. The carbonate budget of a reef describes the net rate of carbonate production resulting from various biologically-, physically- and chemically-driven production and erosion processes. Thus, budget state metrics can provide important information on a reef’s growth potential and on the capacity of reefs to sustain key geo-ecological services such as habitat provision and coastal protection. Whilst various approaches for estimating carbonate budgets exist, census-based methods have gained recent interest because they quantify the contribution of different functional groups and taxa, and allow assessments of the links between changing reef ecology and budget states. However, the present paucity of supporting data on growth and erosion rates for the majority of coral species and reef-associated taxa represents a constraint on these budget estimates and limits meaningful between-site comparisons. In light of the growing interest in using carbonate budgets as a functional reef “health” assessment tool, this review thus considers our current state of knowledge regarding the geographic coverage of existing reef budget states and the availability of relevant supporting data. We use this to highlight current knowledge gaps, future challenges, and opportunities that emerging techniques may offer. The primary aim of this review is to encourage increased research efforts on budget states and underlying metrics in order to better constrain reef carbonate budget estimates from across a broad range of sites and environments.

Effect of carboxyl and hydroxyl groups on adsorptive polysaccharide fouling: A comparative study based on PVDF and graphene oxide (GO) modified PVDF surfaces

We investigated the contribution of different functional groups on polysaccharides to membrane fouling. To achieve so, we examined the adsorption of two typical polysaccharides, i.e., glucan (only –OH) and sodium alginate (enriched –COOH) on surfaces of PVDF membranes with and without graphene oxide (GO) modification. The results suggest that the interaction between carboxyl groups and Ca2+ significantly altered the particle size and charge of sodium alginate. Resultantly, the irreversible fouling of PVDF membrane surface caused by polysaccharide (i.e., sodium alginate) adsorption became more reversible when the concentration of Ca2+ exceeded a critical value. In comparison, glucan containing only hydroxyl groups exhibited unidirectional increase in irreversible fouling along with the increased Ca2+ concentration. Modification of PVDF membrane using GO did alleviate adsorptive fouling, but the Ca2+ bridging between the modified membrane surface and sodium alginate makes the fouling less reversible. Therefore, foulant property and water chemistry should be taken in to account in evaluating the performance of membrane hydrophilization using GO.

Functional group contributions to carbon fluxes in arctic-alpine ecosystems

ABSTRACTOngoing responses to climate change in arctic-alpine ecosystems, including the increasing dominance of deciduous shrubs, involve major shifts in plant functional group composition. Because rates of photosynthesis and respiration and their responses to temperature may vary among plant functional groups, a better understanding of their contributions to carbon fluxes will help improve predictions of how ecosystem changes will affect carbon source-sink relations in globally important tundra regions. We used a sequential harvest method to estimate growing season functional group contributions to net ecosystem exchange (NEE), ecosystem respiration (ER), and gross photosynthesis (GP) in alpine heath-, meadow-, and Salix-dominated shrub communities. We also partitioned ER into aboveground and belowground components in all three communities. Belowground efflux was the dominant component of ER in the heath and meadow communities (63 percent and 88 percent of ER, respectively) but contributed only approximately 40 percent of ER in the shrub community. The dominant functional group in each community contributed most to aboveground exchanges. Estimates for cryptogams were uncertain, but indicated a minor role for bryophytes and lichens in overall exchange. The results of our novel method of partitioning gas-exchange measurements suggest strong differences in the relative proportions of soil versus aboveground respiration and in the contributions of different functional groups in the net carbon exchange of three important arctic-alpine community types, with implications for changes in carbon dynamics as these systems respond to environmental change.

Evaluation of metabolic changes induced by polyphenols in the crayfish Astacus leptodactylus by metabolomics using Fourier transformed infrared spectroscopy

In the present study, the effects of polyphenols on the chemical composition of the hepatopancreas of the Astacus leptodactylus, a highly sought farmed crayfish, have been investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The hepatopancreas spectrum was quite complex and contained several peaks arising from the contribution of different functional groups belonging to protein, lipids and carbohydrates. The PCA statistical analysis revealed that there were significant differences between crayfish fed a diet without polyphenols and crayfish fed a diet containing polyphenols. Such differences indicated an increase in lipids and proteins in the hepatopancreas of polyphenol-fed crayfish. In conclusion, the analysis of the infrared spectral profile of the hepatopancreas of Astacus leptodactylus, allowed us to elucidate the changes in different biomolecules in response to polyphenol treatment, and confirms the suitability of ATR-FTIR spectral data to analyze diet-induced metabolic effects. These considerations, coupled with the small amount of sample and no preparation needed, make ATR-FTIR a useful tool for routine analyses where the metabolic impact of substances is investigated, especially with a large number of samples.

Comparative assessment of magnesium-enhanced-extraction by various sequestering derivatives of 8-hydroxyquinoline via layer-by-layer chemical deposition technique

Design and fabrication of the most highly effective reagent for removal of the target analyte from their matrices represent a great challenge. Therefore, the present work is aimed to explore the potential contribution of different functional groups on the Mg(II) extraction process using Layer-by-layer (LbL) chemical deposition process. Two sequestering reagents, viz 5-phenyl-azo-8-hydroxyquinoline (5PA-8HQ) and 5-azo-benzoate-8-hydroxyquinoline (5AB-8HQ) were synthesized, characterized and compared with the starting 8-hydroxyquinoline (8HQ) material for removal of Mg(II) ion from aqueous solution. The extraction process was evaluated on the basis of surface coverage values (μg/cm2) under different influencing factors. The results of these studies confirmed the superiority of (5AB-8HQ) in double extraction of Mg(II) due to the presence of four reactive functional groups including the quinoline OH and N as well as the azo and carboxyl groups compared to (5PA-8HQ) and (8HQ). The surface coverage values of Mg(II) by (5AB-8HQ), (5PA-8HQ) and (8HQ) were identified as 119.9, 60.8 and 60.8μg/cm2, respectively in presence of pH9.0. Under all experimental conditions, (5PA-8HQ) was identified to similarly behave as (8HQ) without the contribution of azo group in metal binding process. The characterization of deposited Mg(II) complexes confirmed the formation of Mg(II)-(8HQ)2, Mg(II)-(5PA-8HQ)2 and Mg(II)-(5AB-8HQ) in 1:2, 1:2 and 1:1 stoichiometric ratios, respectively to account for the high surface coverage values of Mg(II) by (5AB-8HQ). The effect of reaction dipping time as well as kinetics study, initial metal ion concentration as well as adsorption isotherm models and reaction temperature as well as thermodynamics parameters were also explored in this study.

Stoichiometric linkages between plant litter, trophic interactions and nitrogen mineralization across the litter–soil interface

The common notion for describing N mineralization in models is that it results from decomposer organisms trying to meet their stoichiometric demands based on their own elemental composition and that of the resource. However, in addition to influencing C and nutrient availability, plant litter also influences the composition of both the litter and mineral soil community – importantly not in the same manner – resulting in altered trophic interactions. Since decomposer groups and their consumers vary in their elemental composition and demands, a change in composition and abundance of soil functional groups may result in a change in the stoichiometry of the whole soil food web, thus altering their stoichiometric relations with the available resource with potential functional consequences. We use experimental data and quantitative food web modeling to investigate the impact of the changes in the litter and soil food webs brought about by the differing stoichiometry of plant litter on (a) N mineralization, (b) the contribution of different functional groups to mineralization, and (c) the stoichiometric flexibility of the system, assessed as the ability to mineralize materials with different stoichiometry. Our simulations suggested that the effects of litter stoichiometry on trophic interactions, their impacts on N mineralization and the relative contribution of functional groups may not behave as a continuum across the litter and soil interface. Further, changes in food webs associated with variation in plant stoichiometric traits can influence the relative importance of functional groups, which given their particular stoichiometric demands may affect ecosystem-level N cycling. Our results suggested that litter materials of intermediate N contents, or litter mixtures encompassing materials with different nutrient contents and thus resulting in mixtures of intermediate stoichiometry, may promote food webs that are better suited to deal with changing substrate stoichiometry.

Synthesis, characterization and evaluation of antioxidant activities of some novel chalcones analogues.

BackgroundChalcone, an important intermediate of flavonoid synthetic pathway, has been shown to exhibit diverse biological and pharmacological activities such as anti- cancer, antioxidant, anti-inflammatory, etc.ResultsIn this study, a novel series of chalcones fatty acid esters 5b-e and 6b-e have been synthesized via the reaction of the respective chalcones with either palmitic or stearic acid. Another related class of compounds comprising 2,3-disubstituted chalcones 7b-d and 8b(b’)-d as well as 2-amino-6-(substituted-phenyl)-4-substitutedphenyl-nicotinonitrile derivatives 9a,c,e have been also prepared by both electrophilic and Michael addition reactions, respectively, with the corresponding chalcones. The structures of all compounds are confirmed via a wide range of spectroscopic techniques including IR, 1H and 13C NMR, and mass spectra. Significantly, all synthesized compounds have been tested for their promising antioxidant activities via utilization of 1,1-biphenyl-2-picrylhydrazyl as a free radical scavenging reagent. Surprisingly, the results demonstrated that compound 5e (68.58% at C = 2 μg/ml) was more effective as an antioxidant agent than the ascorbic acid, a commonly used antioxidant. Furthermore, the role and contribution of different functional groups on the antioxidant activity of the synthesized chalcone derivatives are also probed and rationalized in terms of their electronic and structural effect.ConclusionGood activity was noted for chalcone fatty acid esters, with some members recorded higher antioxidant activity than ascorbic acid.

Mechanistic insights into the formation of chloroform from natural organic matter using stable carbon isotope analysis

Chloroform can be naturally formed in terrestrial environments (e.g. forest soils, peatland) by chlorination of natural organic matter (NOM). Recently, it was demonstrated that natural and anthropogenic chloroform have a distinctly different carbon isotope signature that makes it possible to identify its origin in soil and groundwater. In order to evaluate the contribution of different functional groups to chloroform production and factors controlling the isotopic composition of chloroform, carbon isotope trends during chlorination of model compounds, soil organic matter (SOM) and humic acids were evaluated, and apparent kinetic isotope effects (AKIEs) quantified. Phenol and propanone were selected as model compounds representing common functional groups in NOM. Chlorination was induced by hypochlorous acid to mimic natural chlorination. The pH ranged between 4 and 8 to cover typical soil conditions. For each model compound and pH, different AKIEs were observed. For phenol, the AKIE was normal at pH 4 (1.0156±0.0012) and inverse at pH 8 (0.9900±0.0007). For 2-propoanol, an opposite pH dependence was observed with an inverse AKIE at pH 4 (0.9935±0.0007) and a normal AKIE at pH 8 (1.0189±0.0016). The variations of the AKIE values suggest that the rate-limiting step of the reaction is either the re-hybridization of the carbon atom involved in chloroform formation or the hydrolysis of trichloroacetyl intermediates depending on the nature of functional group and pH. The chloroform formation from humic acid and SOM gives rise to small isotope variations. A comparison of the isotopic trends of chloroform formed from humic acid and SOM with those found for the model compounds suggest that opposed AKIE associated with the chlorination of phenolic and ketone moieties of NOM partly compensate each other during chlorination of NOM indicating that different types of functional groups contribute to chloroform formation.

Base catalyzed racemization of amino acid derivatives

Amino acid thioesters used as substrates for a chemo-enzymatic dynamic kinetic resolution (DKR) must be designed with a high enough acidity to be rapidly racemized in the presence of a suitable base. Kinetic data obtained from experimental proton exchange rates are correlated with thermodynamic data for the proton abstraction based on the density functional theory (DFT) calculations. The good correlation obtained allows to evaluate the contribution of different functional groups to the carbon acidity and to define bases able to perform the required racemization.

Book reviewBiodiversity, Ecosystem Functioning, and Human Wellbeing—An Ecological and Economic Perspective, S. Naeem, D.E. Bunker, A. Hector, M. Loreau, C. Perrings (Eds.), Oxford University Press, Oxford (2010), 368 pp., £75.00, 37.50, ISBN: 978-0-19-954795-1 (hardback), 978-0-19-954796-8 (paperback)

The common notion for describing N mineralization in models is that it results from decomposer organisms trying to meet their stoichiometric demands based on their own elemental composition and that of the resource. However, in addition to influencing C and nutrient availability, plant litter also influences the composition of both the litter and mineral soil community – importantly not in the same manner – resulting in altered trophic interactions. Since decomposer groups and their consumers vary in their elemental composition and demands, a change in composition and abundance of soil functional groups may result in a change in the stoichiometry of the whole soil food web, thus altering their stoichiometric relations with the available resource with potential functional consequences. We use experimental data and quantitative food web modeling to investigate the impact of the changes in the litter and soil food webs brought about by the differing stoichiometry of plant litter on (a) N mineralization, (b) the contribution of different functional groups to mineralization, and (c) the stoichiometric flexibility of the system, assessed as the ability to mineralize materials with different stoichiometry. Our simulations suggested that the effects of litter stoichiometry on trophic interactions, their impacts on N mineralization and the relative contribution of functional groups may not behave as a continuum across the litter and soil interface. Further, changes in food webs associated with variation in plant stoichiometric traits can influence the relative importance of functional groups, which given their particular stoichiometric demands may affect ecosystem-level N cycling. Our results suggested that litter materials of intermediate N contents, or litter mixtures encompassing materials with different nutrient contents and thus resulting in mixtures of intermediate stoichiometry, may promote food webs that are better suited to deal with changing substrate stoichiometry.

Contribution of different functional groups to the diet of major predatory fishes at a seagrass meadow in northeastern Japan

We examined the variation in habitat use and diet of three dominant fish species ( Myoxocephalus brandti, Pholidapus dybowskii, and Pholis crassispina) in a seagrass meadow in the Akkeshi-ko estuary in northeastern Japan, where broad and dense Zostera marina beds exist, using a semi-quantitative census of the fishes and analyses of their stomach contents. Differences among the three fish species in the temporal variation in abundance of each age class (mainly 1- and 2-year age classes) indicated that the temporal pattern of utilization of the seagrass meadow were different among them. In the semi-quantitative dietary analysis, two prey categories, i.e., taxonomic group (order and suborder) and functional group, were used to explain the variation in prey composition with size-dependent changes. The six prey functional groups were classified based on the ecological traits of the prey, i.e., trophic level, size, and life type (habitat and behavior). Ontogenetic shifts in prey of the three fish species could be fully explained by a combination of the two prey categories, and not by the use of only one category (taxonomic or functional group). The pattern of ontogenetic shifts in prey differed among the fish species and size (age) classes. These results indicate that segregation of habitat (seagrass meadow) and prey group (taxonomic and functional group) is performed among the three species, which may contribute to their coexistence in this estuary.

Effect of arsenic intoxication on proteins and lipids of Labeo rohita gill tissues: An FT-IR study

In the present work, an attempt has been made to analyze the arsenic induced biochemical changes in the gill tissues of freshwater fish Labeo rohita using Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectrum of gill tissue is quite complex and contains several bands arising from the contribution of different functional groups belonging to lipids, proteins, and others. FT-IR spectra reveal significant differences in absorbance intensities and areas between the control and arsenic intoxicated gill tissues. The amide I and II peaks observed at 1654 and 1542 cm−1 suggest that the protein is dominated by α-helical structure in the gill tissues. The result further shows that due to arsenic intoxication, α-helical structure decreases significantly with an increase in β-sheet and random coil structures. In conclusion, the present study shows that the gill tissues are vulnerable to arsenic intoxication. The result further suggests that arsenic intoxication induces significant alteration on the major biochemical constituents such as lipids, proteins and nucleic acids, which can be easily evidenced by FT-IR spectroscopy.