Freeze-dried Tissue Research Articles

Seasonal and diurnal variations in leaf aroma volatiles of Cinnamomum tamala (Buch.-Ham.) T. Nees & Eberm as evidenced from metabolite profiling, histochemical and ultrastructural analyses.

Though the leaves of Cinnamomum tamala is extensively employed in culinary applications due to its rich aroma and therapeutic properties, the produce exhibits variability in composition and contents of leaf essential oil due to fluctuations in climatic conditions and harvesting time. This work evaluated the impact of seasonal and diurnal variations on the composition and contents of aroma volatiles in the mature leaves of C. tamala. In summer, the profile of aroma volatile was dominated by phenylpropanoids (112.96±24.11μg/g of freeze-dried leaf tissue) while in winter monoterpenes (58.45±8.194μg/g of freeze-dried leaf tissue) acquired the dominance. The variability in the contents of primary metabolites was shown to be influenced by the harvesting season and time. Organic acids and sugars showed highest accumulation in leaves harvested during summer evening and winter morning, respectively. Histochemical study showed the presence of lipids and terpenes in the secretory cells as revealed through sudan III and NaDi staining. The ontogeny of secretory oil cells that accumulate essential oil were elucidated through ultrastructural study.

Faster ciguatoxin extraction methods for toxicity screening

Ciguatera poisoning (CP) is a severe global public health problem caused by the consumption of seafood products contaminated with ciguatoxins (CTXs). The growing demand for seafood products requires high-throughput testing for CTX-susceptible seafood, however complex extraction and slow cleanup methods inhibit this goal. Herein, several methods for extracting CTXs from fish tissue were established and compared; these methods are sensitive, specific, and valid while achieving higher sample extraction throughput than currently established protocols. The trial fish material was generated from multiple species, with different physical conditions (wet and freeze-dried tissue), and naturally contaminated with various CTXs (i.e., CTX-1B, CTX-3C, and C-CTX-1), thus ensuring these methods are robust and broadly applicable. The extraction methods used were based on mechanical maceration with acetone or methanol or enzymatic digestion followed by acetone and ethyl acetate extraction. Crude extracts were investigated for CTX-like toxicity using an in vitro mouse neuroblastoma (N2a) cell-based assay (CBA). Among the three methods, there was no significant difference in toxin estimates (p = 0.219, two-way ANOVA), indicating their interchangeability. For speed (> 16 samples/day), accuracy (100%), and CTX analog retention confirmation by liquid chromatography-tandem mass spectrometry (LC‒MS/MS), the preferred extraction methods were both methanol and enzyme-based. All extraction methods post hoc confirmation of CTX analogs successfully met international seafood market-based CTX contaminant guidance. These methods can drastically increase global CTX screening capabilities and subsequently relieve sample processing bottlenecks, inhibiting environmental and human health-based CTX analysis.

Attenuated total reflection Fourier-transform infrared spectroscopy for the prediction of hormone concentrations in plants.

Plant hormones are important in the control of physiological and developmental processes including seed germination, senescence, flowering, stomatal aperture, and ultimately the overall growth and yield of plants. Many currently available methods to quantify such growth regulators quickly and accurately require extensive sample purification using complex analytic techniques. Herein we used ultra-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) to create and validate the prediction of hormone concentrations made using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectral profiles of both freeze-dried ground leaf tissue and extracted xylem sap of Japanese knotweed (Reynoutria japonica) plants grown under different environmental conditions. In addition to these predictions made with partial least squares regression, further analysis of spectral data was performed using chemometric techniques, including principal component analysis, linear discriminant analysis, and support vector machines (SVM). Plants grown in different environments had sufficiently different biochemical profiles, including plant hormonal compounds, to allow successful differentiation by ATR-FTIR spectroscopy coupled with SVM. ATR-FTIR spectral biomarkers highlighted a range of biomolecules responsible for the differing spectral signatures between growth environments, such as triacylglycerol, proteins and amino acids, tannins, pectin, polysaccharides such as starch and cellulose, DNA and RNA. Using partial least squares regression, we show the potential for accurate prediction of plant hormone concentrations from ATR-FTIR spectral profiles, calibrated with hormonal data quantified by UHPLC-HRMS. The application of ATR-FTIR spectroscopy and chemometrics offers accurate prediction of hormone concentrations in plant samples, with advantages over existing approaches.

Systemic biochemical changes in pepper (Capsicum annuum L.) against Rhizoctonia solani by kale (Brassica oleracea var. acephala L.) green manure application

BackgroundIn the search for new alternatives to avoid the problems associated with the use of synthetic chemical fungicides in agriculture, the use of green manure (GrM) could help combat fungal diseases of crops, such as those produced by the necrotrophic pathogen Rhizoctonia solani. In the case of the use of Brassica tissues as GrM, it could have an elicitor capacity for systemic plant resistance.ResultsWe used kale leaves as a GrM and applied it to pepper plants infected with R. solani. The application of freeze-dried kale tissues to the roots of pepper plants produced a systemic activation of foliar defences via the salicylic acid (SA) and ethylene (ET) pathways, significantly reducing pathogen damage. In addition, this systemic response led to the accumulation of secondary defence metabolites, such as pipecolic acid, hydroxycoumarin and gluconic acid, in leaves. Remarkably, pepper plants treated with lyophilised kale GrM accumulated glucosinolates when infected with R. solani. We also confirmed that autoclaving removed part of the glucobrassicin (85%) and sinigrin (19%) content of the kale tissues.ConclusionsGrM kale tissues can activate systemic defences in bell pepper against foliar pathogens through SA/ET hormonal pathways, accumulating secondary defence metabolites.

Impact of frequency and duration of freeze-dried inactivated tissue culture hepatitis A vaccine (Aimmugen®) vaccination on antibody titers; a japanese cross-sectional study

BackgroundThe effect of the timing of additional doses and the long-term persistence of lyophilized inactivated tissue culture hepatitis A (HA) vaccine (Aimmugen®) on antibodies is unknown. MethodsA single-center, cross-sectional, observational study was conducted in collaboration with the Japan Air Self-Defense Force, whose personnel were immunized with Aimmugen® when deployed to endemic areas. Patients who consented to this study after a medical examination with blood sampling between June 2022 and February 2023 were included; HA-IgG level in the residual serum was measured using the chemiluminescent immunoassay method. The exact vaccination history was investigated based on immunization records maintained by the Ministry of Defense, and a questionnaire was used to collect confounding factors. ResultsOf the 181 participants observed, 49 were in the unvaccinated group, and 132 were in the vaccinated group. Out of the vaccinated group, 6.8 % received either one or two doses, 40.9 % received three doses, and 52.3 % received more than four doses. IgG antibody titers (S/CO value) in each group (0, 1 or 2, 3, and over 4) increased in a frequency-dependent manner, with those vaccinated over four times showing significantly higher IgG antibody titers than all other groups (0.19 ± 0.10 vs 3.66 ± 3.00 vs 7.63 ± 3.57 vs 10.57 ± 1.86, respectively). When the number of months elapsed from the last vaccination to the date of blood collection in each group was plotted against IgG antibody titer, the slope of the regression line flattened out from a decreasing trend in the order 1 or 2, 3, over 4. ConclusionsThree doses of Aimmugen® are efficacious, but four or more doses induce more robust and sustained antibody production. Additionally, four or more doses may be effective when there is a need to ensure long-term immunity or risk of prolonged exposure.

Optimization of Targeted Plant Proteomics Using Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS).

This study was conducted to optimize a targeted plant proteomics approach from signature peptide selection and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analytical method development and optimization to sample preparation method optimization. Three typical protein extraction and precipitation methods, including trichloroacetic acid (TCA)/acetone method, phenol method, and TCA/acetone/phenol method, and two digestion methods, including trypsin digestion and LysC/trypsin digestion, were evaluated for selected proteins related to the impact of engineered nanomaterials (ENMs) on wheat (Triticum aestivum) plant growth. In addition, we compared two plant tissue homogenization methods: grinding freeze-dried tissue and fresh tissue into a fine powder using a mortar and pestle aided with liquid nitrogen. Wheat plants were grown under a 16 h photoperiod (light intensity 150 μmol·m-2·s-1) for 4 weeks at 22 °C with a relative humidity of 60% and were watered daily to maintain a 70-90% water content in the soil. Processed samples were analyzed with an optimized LC-MS/MS method. The concentration of selected signature peptides for the wheat proteins of interest indicated that the phenol extraction method using fresh plant tissue, coupled with trypsin digestion, was the best sample preparation method for the targeted proteomics study. Overall, the optimized approach yielded the highest total peptide concentration (68,831 ng/g, 2.4 times the lowest concentration) as well as higher signature peptide concentrations for most peptides (19 out of 28). In addition, three of the signature peptides could only be detected using the optimized approach. This study provides a workflow for optimizing targeted proteomics studies.

Freeze-dried snacks obtained from frozen vegetable by-products and apple pomace – Selected properties, energy consumption and carbon footprint

Valorisation of food waste is one of the goals that food industry needs to achieve in terms of sustainable development. The aim of the research has been to analyse selected properties of freeze-dried vegetable snacks obtained from wholesome waste derived from the fruit and vegetable industry, such as frozen vegetable by-products and apple pomace as well as to estimate carbon footprint as the technological process output on the basis of the energy used for the purpose of producing snacks. Properties of snacks, such as water content and activity, shrinkage, density, porosity and hardness, were determined using common methodology. The water content of the finished products was very low (<1.5%) and determined the water activity below 0.02. Technological operations, such as grinding, caused destruction of the cell structure of the ingredients, which subsequently made the product structure inhomogeneous and more dense than most of the freeze-dried plant tissues. The snacks were porous and featured by hardness of 79.43–113.26 N. The colour depended on their composition, and freeze-drying caused the products to brighten significantly. The estimated carbon footprint (CF) depended on the technological process. Freeze-drying had the most significant impact upon the CF, accounting for 86–87%. The use of apple pomace powder as a structure- and texture-forming additive constitutes the subject matter representing great prospects for further research.

Comparison of extraction and clean-up methods for comprehensive screening of organic micropollutants in fish using gas chromatography coupled to high-resolution mass spectrometry

Monitoring the vast number of micropollutants in the environment by using comprehensive chemical screening is a major analytical challenge. The aim of this study was to evaluate a comprehensive analysis method for screening purposes of fish muscle samples by comparing sample preparation methods for a broad range of mid-to non-polar contaminants. Five extraction and three clean-up methods were evaluated for the analysis of 60 compounds with a log Kow range between 0.8 and 8.3 in fish. Both fresh and freeze-dried muscle tissue and extraction sodium sulphate blanks were included to assess recoveries and matrix effects. The performance of the different methods was evaluated using both comprehensive target and nontarget analysis using high resolution mass spectrometry (HRMS).The results showed that open-column and ultrasonication extractions (recoveries mostly between 20 and 160 %) resulted in higher recoveries than accelerated solvent extraction (ASE) (recoveries mostly between 20 and 80 %) and bead mixer homogenization extractions (recoveries between 0 and 50 % for the whole Kow range). Multilayer silica was the clean-up method resulting in the lowest matrix effects and highest recoveries, however some compounds (mostly pesticides) were denatured under the acidic conditions used. The convenient and time efficient ultrasonication extraction followed by deactivated silica clean-up proved to be promising for both target and nontarget approaches. The large difference in recoveries and number of detected peaks using target and nontarget approaches between fresh and freeze-dried fish seen for all methods calls for careful consideration, and further studies are needed to improve performance for screening of mid-to non-polar compounds in freeze-dried fish.

Distribution of polycyclic aromatic hydrocarbons (PAHs) in the bottom sediments of a dam reservoir, their interaction with organic matter and risk to benthic fauna

PurposeThe aims of the study were to investigate the interaction between fractions of organic matter and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments and to use mussels as passive biomonitors and consensus-based sediment quality guidelines for ecological risk assessment in sediments.MethodsBottom sediment samples were taken from 46 points located in the Rożnów reservoir (Poland). The sediment organic matter (SOM) characteristics included total carbon (TC), total organic carbon (TOC), humic acid carbon (Cha), fulvic acid carbon (Cfa), non-hydrolysing carbon (Cnh), and dissolved organic carbon (DOC). The extraction procedure was carried out in bottom sediments as well as in freeze-dried mussel tissue samples to directly determine the accumulation potential of PAHs to the living organisms in their natural environment.ResultsThe content of organic matter fractions was in the following order: Cfa (fulvic acid) > Cnh (non-hydrolysing carbon) > Cha (humic acid) > DOC (dissolved organic carbon). The mean ∑16PAHs (μg kg−1) concentration was 1755.2 ± 724 (total) and 256 ± 254 (bioavailable) in sediments and 1740 ± 72.2 in the mussel tissues. A significant positive correlation was found between the concentration of PAHs in the mussel tissues and the total and bioavailable concentration of PAHs in bottom sediments.ConclusionThe PAH concentration in bottom sediments depended on the stabile carbon forms Cnh. Principal component analysis (PCA) suggests that the fine fraction can significantly increase the bioavailability of PAHs and can be an important factor in the distribution of PAHs in the sediments.

Effects of brainstem lesions on amino acid levels in the rat cochlear nucleus

There is evidence for glutamate, γ-amino butyric acid (GABA), and glycine as neurotransmitters of centrifugal pathways to the cochlear nucleus, but the quantitative extent of their contributions to amino acid neurotransmission in cochlear nucleus regions has not been known. We used microdissection of freeze-dried tissue sections of rat cochlear nucleus, with mapping of sample locations, combined with a high performance liquid chromatography (HPLC) assay, to measure amino acid levels in cochlear nucleus subregions of rats with unilateral lesions of centrifugal pathways to the cochlear nucleus. In rats with lesions transecting all or almost all pathways to the cochlear nucleus from brain stem regions, GABA, aspartate, and glutamate levels were reduced, compared to contralateral values, in almost all ipsilateral cochlear nucleus regions. The largest reductions, in dorsal (DCN), anteroventral (AVCN), and posteroventral (PVCN) cochlear nucleus regions, approached 50% for GABA, 40% for aspartate, and 30% for glutamate. In contrast, glutamine and taurine levels were typically higher in lesioned-side cochlear nucleus regions than contralaterally. Effects on glycine levels were mixed but usually included increased lesioned-side values compared to contralateral, probably reflecting a balance between increases during protein breakdown and decreases of free glycine in transected pathways. More limited lesions transecting just dorsal pathways showed much less effect on amino acid levels. Lesion of the ipsilateral trapezoid body connection plus ipsilateral superior olivary nuclei resulted in decreases of GABA, aspartate, and glutamate levels especially in ventral cochlear nucleus regions. No clear contralateral effects of this lesion could be shown. The results most strongly support centrifugal GABAergic pathways to the cochlear nucleus, providing almost half of GABAergic neurotransmission in most regions. Our results support and extend previously published measurements of lesion effects on GABA uptake and release in cochlear nucleus subdivisions.

Behavioral analysis of rock bream Oplegnathus fasciatus reveals a strong attraction potential for sea urchin extracts

Monitoring fish movement is important to understand how physiology adapts to environmental change. To explore the applicability of a video tracking system for determining if chemical cues attract or repel aquatic animals, the movement patterns of rock bream, Oplegnathus fasciatus, were analyzed upon exposure to various materials, including extracts of sea urchin, rock worm, bait worm, krill, barley kernel, and commercial fish feed. Pellets were prepared by mixing freeze-dried tissues with a cellulose and corn flour mixture. Behavioral analysis was carried out with five fish that had been acclimated in the adaptation zone of a Y-shaped tank. Preference toward chemical cues was quantified by assessing the frequency rock bream were observed in a discrete zone around the test material located at the end of each arm and the duration each fish stayed in each zone. The analysis of fish movement upon exposure to commercial feed and barley kernel at each end, respectively, indicated a clear preference toward the feed relative to the barley kernel. Movement responses were further tested with pellets containing extracts of sea urchin, one of the species collected on a large scale, and other materials including krill and worms. A stronger preference toward sea urchin (100%) was observed based on the duration of stay in the test zone, compared to krill (90.1 ± 44.2%), bait worm (81.1 ± 39.1%), rock worm (73.7 ± 28.9%), and barley (63.9 ± 25.9%), under the conditions tested. A detailed comparison of rock bream movements toward each material revealed significant differences in frequency and duration, respectively, between pairs of test materials including krill (74 ± 29.8 and 375.6 ± 118.9) vs. rock worm (41.5 ± 18.7 and 160.2 ± 42.6), krill (86.3 ± 22.9 and 477.1 ± 84) vs. bait worm (36.2 ± 5.5 and 166.1 ± 50.7), and rock worm (45.9 ± 26.2 and 213.7 ± 100.1) vs. bait worm (34.6 ± 21.7 and 159.5 ± 98.5). Rock bream exhibited preference for the test materials in the following order: commercial fish feed &gt; sea urchin &gt; krill &gt; rock worm &gt; bait worm &gt; barley. The results suggest a higher potency of sea urchin extract as a rock bream fishing bait compared to the other materials that are used as commercial bait.

Using Near-infrared reflectance spectroscopy (NIRS) to predict glucobrassicin concentrations in cabbage and brussels sprout leaf tissue

BackgroundGlucobrassicin (GBS) and its hydrolysis product indole-3-carbinol are important nutritional constituents implicated in cancer chemoprevention. Dietary consumption of vegetables sources of GBS, such as cabbage and Brussels sprouts, is linked to tumor suppression, carcinogen excretion, and cancer-risk reduction. High-performance liquid-chromatography (HPLC) is the current standard GBS identification method, and quantification is based on UV-light absorption in comparison to known standards or via mass spectrometry. These analytical techniques require expensive equipment, trained laboratory personnel, hazardous chemicals, and they are labor intensive. A rapid, nondestructive, inexpensive quantification method is needed to accelerate the adoption of GBS-enhancing production systems. Such an analytical method would allow producers to quantify the quality of their products and give plant breeders a high-throughput phenotyping tool to increase the scale of their breeding programs for high GBS-accumulating varieties. Near-infrared reflectance spectroscopy (NIRS) paired with partial least squares regression (PLSR) could be a useful tool to develop such a method.ResultsHere we demonstrate that GBS concentrations of freeze-dried tissue from a wide variety of cabbage and Brussels sprouts can be predicted using partial least squares regression from NIRS data generated from wavelengths between 950 and 1650 nm. Cross-validation models had R2 = 0.75 with RPD = 2.3 for predicting µmol GBS·100 g−1 fresh weight and R2 = 0.80 with RPD = 2.4 for predicting µmol GBS·g−1 dry weight. Inspections of equation loadings suggest the molecular associations used in modeling may be due to first overtones from O–H stretching and/or N–H stretching of amines.ConclusionsA calibration model suitable for screening GBS concentration of freeze-dried leaf tissue using NIRS-generated data paired with PLSR can be created for cabbage and Brussels sprouts. Optimal NIRS wavelength ranges for calibration remain an open question.

Soft X-ray induced radiation damage in thin freeze-dried brain samples studied by FTIR microscopy

In order to push the spatial resolution limits to the nanoscale, synchrotron-based soft X-ray microscopy (XRM) experiments require higher radiation doses to be delivered to materials. Nevertheless, the associated radiation damage impacts onthe integrity of delicate biological samples. Herein, the extent of soft X-ray radiation damage in popular thin freeze-dried brain tissue samples mounted onto Si3N4 membranes, as highlighted by Fourier transform infrared microscopy (FTIR), is reported. The freeze-dried tissue samples were found to be affected by general degradation of the vibrational architecture, though these effects were weaker than those observed in paraffin-embedded and hydrated systems reported in the literature. In addition, weak, reversible and specific features of the tissue-Si3N4 interaction could be identified for the first time upon routine soft X-ray exposures, further highlighting the complex interplay between the biological sample, its preparation protocol and X-ray probe.

Comparative evaluation of two Fusarium oxysporum f. sp. lycopersici strains grown on two different carbon sources: LC-MS - based secretome study after in vivo 15N metabolic labeling

To get new insight on the pathogenicity of Fusarium oxysporum f. sp. lycopersici, metabolic labeling was performed, and secretomes of the wild type strain 4287 (W) and non-virulent mutant ΔchsV (M) were compared while switching the main carbon source from glucose (Glc) to the freeze-dried vascular tomato tissue (VTT). 14N- or 15N-containing KNO3 was used for fungal growth and two combined (14N/15N) protein extracts were obtained: 1- W + M in Glc; 2- W + M in VTT. Trypsin digests of 1 and 2 were analyzed by capHPLC-ESI-QTOF-MS and Skyline was applied to compare the abundances of individual proteins between two strains in each sample and between the samples. Protein grouping was suggested as follows: (1) seven proteins apparently adsorbing on VTT were of importance during the initial stage of invasion; (2) three adsorbing on VTT were involved in compensative mutant adjustment, in growth and nutrients supply; (3) eleven might contribute in pathogenicity without direct interaction with the plant cell wall; (4) fourteen were involved in mutant adaptation, fungal growth and nutrients supply, not excluding their role in pathogenicity. The above proteins comprised carbohydrate-active enzymes, protein/peptide- and lipid-hydrolyzing enzymes, few classified as effectors (NEP-like, serine protease, GLEYA adhesion domain, LysM domain), catalyzing redox processes and few of unknown function.

A histological study of mouse tissues and water loss following lyophilization

ABSTRACTLyophilization is a practical method for product storage and transportation; it commonly is used in the food and pharmaceutical industries. Lyophilization also is used for preserving biological samples such as serum, plasma and animal tissues. We found that lyophilization does not affect the stability of RNAs and proteins in tissue samples. To investigate histological characteristics, we prepared lyophilized tissues for paraffin sectioning and hematoxylin and eosin (H & E) staining. We also measured water loss from organs during lyophilization. We used immunohistochemistry of frozen brain sections to identify potential protective effects of three concentrations of sucrose, glucose and trehalose against the effects of lyophilization. H & E staining revealed vacuoles in heart, lung, liver, kidney, spleen and brain after lyophilization without pretreatments, especially heart and kidney. We found that 10% solutions of sucrose, glucose and trehalose helped preserve tissue morphology. Immunohistochemistry of frozen brain tissue showed that 10% glucose and 30% sucrose preserved cellular characteristics and immunogenicity following lyophilization. Lyophilization removed > 70% of the water from organs, and lyophilized tissues without protectants were not suitable for histological study. Overall, we found that 10% glucose helped preserve both optimal tissue morphology and immunogenicity of freeze-dried tissue.

Comprehensive Evaluation of Parameters Affecting One-Step Method for Quantitative Analysis of Fatty Acids in Meat.

Despite various direct transmethylation methods having been published and applied to analysis of meat fatty acid (FA) composition, there are still conflicting ideas about the best method for overcoming all the difficulties posed by analysis of complex mixtures of FA in meat. This study performed a systematic investigation of factors affecting a one-step method for quantitative analysis of fatty acids in freeze-dried animal tissue. Approximately 280 reactions, selected using factorial design, were performed to investigate the effect of temperature, reaction time, acid concentration, solvent volume, sample weight and sample moisture. The reaction yield for different types of fatty acids, including saturated, unsaturated (cis, trans and conjugated) and long-chain polyunsaturated fatty acids was determined. The optimised condition for one-step transmethylation was attained with four millilitres 5% sulfuric acid in methanol (as acid catalyst), four millilitres toluene (as co-solvent), 300 mg of freeze-dried meat and incubation at 70 °C for 2 h, with interim mixing by inversion at 30, 60 and 90 min for 15 s. The optimised condition was applied to meat samples from different species, covering a broad range of fat content and offers a simplified and reliable method for analysis of fatty acids from meat samples.

Stable isotope analyses reveal unique trophic role of reef manta rays (Mobula alfredi) at a remote coral reef.

Stable isotope analyses provide the means to examine the trophic role of animals in complex food webs. Here, we used stable isotope analyses to characterize the feeding ecology of reef manta rays (Mobula alfredi) at a remote coral reef in the Western Indian Ocean. Muscle samples of M. alfredi were collected from D'Arros Island and St. Joseph Atoll, Republic of Seychelles, in November 2016 and 2017. Prior to analysis, lipid and urea extraction procedures were tested on freeze-dried muscle tissue in order to standardize sample treatment protocols for M. alfredi. The lipid extraction procedure was effective at removing both lipids and urea from samples and should be used in future studies of the trophic ecology of this species. The isotopic signatures of nitrogen (δ15N) and carbon (δ13C) for M. alfredi differed by year, but did not vary by sex or life stage, suggesting that all individuals occupy the same trophic niche at this coral reef. Furthermore, the isotopic signatures for M. alfredi differed to those for co-occurring planktivorous fish species also sampled at D'Arros Island and St. Joseph Atoll, suggesting that the ecological niche of M. alfredi is unique. Pelagic zooplankton were the main contributor (45%) to the diet of M. alfredi, combined with emergent zooplankton (38%) and mesopelagic prey items (17%). Given the extent of movement that would be required to undertake this foraging strategy, individual M. alfredi are implicated as important vectors of nutrient supply around and to the coral reefs surrounding D'Arros Island and St. Joseph Atoll, particularly where substantial site fidelity is displayed by these large elasmobranchs.

Impact of pulsed electric fields on physical properties of freeze-dried apple tissue

Abstract The aim of this study was to analyze the impact of pulsed electric field (PEF) pre-treatment of apple tissue on kinetics of freeze-drying preceded by vacuum freezing and physical properties of such processed material. PEF intensified freeze-drying kinetics and thus reduced processing time by 57% in comparison to untreated apples slices. Furthermore, the effective water diffusion coefficient increased by 44% as a result of PEF application. Water activity changes during storage of freeze-dried apple tissue were more evident in the case of untreated material albeit initial water activity was higher in the case of electroporated samples. As proved by thermal properties measurements these differences were linked to higher crystallinity of the PEF treated samples (35.5%) in comparison to the untreated material (11.0%). The freeze-dried fruits subjected to PEF pretreatment absorbed more water than the untreated samples while no changes were observed for hygroscopicity and loss of the soluble solids during rehydration. Industrial relevance Obtained results confirm that application of pulsed electric field before freeze-drying makes possible to obtain high quality freeze-dried product preceded by vacuum freezing performed inside freeze-dryer which could reduce freeze-drying time. Since the rehydration capacity of PEF treated material, expressed as ability to absorb water, is better than untreated samples the application of this method could be beneficial when designing instant products. Performed research indicates also that PEF treated freeze-dried apples exhibit better stability expressed by water activity which in turn is related to crystallinity. What more, higher crystallinity of PEF pre-treated freeze-dried samples not only complements the explanation of different physical properties in comparison with intact freeze-dried material but also suggest that sensorial properties may vary.

Vibrational spectroscopy-based quantification of liver steatosis

The liver plays a central role in lipid metabolism, and abnormal lipid accumulation in the liver is a key feature of Non-Alcoholic Fatty Liver Disease. In experimental studies, quantification of liver steatosis is commonly based on lipids staining or biochemical analysis. Here, we present a spectroscopic approach for quantitative analysis of the lipid content in the freeze-dried liver. The method is based on vibrational spectroscopy (Raman and infrared) measurements applied for Partial Least Squares (PLS) regression modeling. The obtained PLS models show a good correlation of the spectroscopic data with the reference histological evaluation of steatosis based on Oil Red O (ORO)-stained images of liver cross sections. Vibrational spectroscopy with PLS-based modeling described here represents a useful approach for the fast assessment of the liver steatosis in a small sample of freeze-dried liver tissue. In conclusion, our work demonstrates the easy-to-use method that can be applied in laboratory routine as a beneficial alternative to the established ORO staining.

Nutrition of marine mesograzers: integrating feeding behavior, nutrient intake and performance of an herbivorous amphipod.

Consumers can regulate the acquisition and use of nutrients through behavioral and physiological mechanisms. Here, we present an experimental approach that simultaneously integrates multiple nutritional traits, feeding assays, and juvenile performance to assess whether a marine herbivore (the amphipod Ampithoe valida) regulates the intake of elements (carbon and nitrogen), macronutrients (protein and non-protein) or both when offered freeze-dried tissues of seaweeds varying in nutritional content. We assessed behavioral regulation of nutrients in three ways. First, during no-choice assays, we found that amphipods ingested similar amounts of carbon, but not nitrogen, non-protein and protein, across algal diets. Second, herbivore intake rates of carbon, protein and non-protein components across no-choice assays was similar to intake rates when offered a choice of foods. Third, variation in intake rates of carbon and non-protein components among algal diets was significantly greater than was tissue content of these components, while variation in intake rates of nitrogen was significantly lower; differences in protein intake variation was equivocal. While these analytical approaches are not uniformly consistent, carbon and nitrogen seem to emerge as the nutrient components that are more strongly regulated by A. valida. Juveniles reared on single diets shown patterns of survivorship, growth and reproduction that could not be predicted by these feeding preferences, nor nutrient content. We conclude that an integrative approach that considers the intake of multiple nutrients potentially yields insights into feeding behavior and its performance consequences.