14C-amino Acids Research Articles

Improved Assessment of Soil Nonextractable Residues of the Pyrethroid Insecticide Cyphenothrin.

The metabolic fate of pyrethroid insecticide cyphenothrin (1) [(RS)-α-cyano-3-phenoxybenzyl (1RS)-cis-trans-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate] in soils was investigated using 14C-labeled (1R)-cis/trans isomers at the cyclopropane ring. Both isomers degraded with half-lives of 19.0-47.4 days, and 48.9-56.0% and 27.5-38.7% of the applied radioactivity (AR) were mineralized to CO2 and incorporated into nonextractable residues (NER), respectively, after 120 days at 20 °C. NER analyses revealed 37.5-42.2% (cis-1) and 44.9-54.1% (trans-1) of each residue at 30/120 days were comprised of 14C-amino acids (AAs) as microbial products. Assuming that 50% of microbial biomass is AAs, it was estimated that 11.3-22.9%AR (cis-1, 75.0-84.4% of NER) and 13.9-30.4%AR (trans-1, 89.8-108.2% of NER) were nonhazardous biogenic NER (bio-NER), while type I/II xenobiotic NER (xeno-NER) characterized by silylation was insignificant at 0.9-1.0%/2.8-3.3%AR (cis-1). Detailed 14C-AA quantitation indicated a high relevance of the tricarboxylic acid cycle and pyruvate pathway during bio-NER formation, offering new insights into the microbial assimilation of the chrysanthemic moiety.

Vitamin C-amino acid interactions in aqueous solutions: Volumetric and interfacial properties

Nature of interactions occurring in aqueous solutions have been studied to understand various phenomena such as protein stabilization, drug-delivery, and food preservation. These interactions have been studied by measuring physicochemical properties of mixed aqueous solutions. Herein, we have measured the volumetric and interfacial properties of vitamin C (VC) in aqueous solutions of amino acids (Glycine, Gly; L-Leucine, Leu). Volumetric were studied at temperatures (298.15 K to 313.15 K). Transfer volumes were obtained from infinite dilution partial molar volumes of VC in aqueous Gly-and Leu-solutions. Positive transfer volumes (∆tV2° and ∆tK2) were observed, which decreases as Gly > Leu, suggesting dominance of hydrophilic-ionic interactions. Double derivative, (∂2V2° /∂T2)P suggest chaotropic nature of VC in presence of amino acids. Nature of interactions influencing interfacial properties (contact angle and surface tension) has also been evaluated at 298.15 K. Solute-co-solute interactions not much influence the interfacial properties.

Amino Acid Metabolism in Gilthead Seabream Is Affected by the Dietary Protein to Energy Ratios

The dietary protein to energy ratio (P/E) has proven to influence protein utilization and/or growth in several fish species. This study intended to unravel the bioavailability and metabolic fate of lysine and methionine in gilthead seabream (Sparus aurata) juveniles fed plant diets with different P/E ratios. Seabream juveniles were fed two isonitrogenous diets (45% crude protein) differing in crude lipids (20 and 14%): LowP/E ( P / E ratio = 20.0 mg protein k J − 1 ) and HighP/E ( P / E ratio = 21.4 mg protein k J − 1 ). After three weeks, fish ( 11.6 ± 4.3 g ) were tube-fed the respective diet labelled with 14C-protein (L-amino acid mixture), 14C-lysine, or 14C-methionine. Protein, lysine, and methionine utilization were determined based on the proportion of 14C-amino acid evacuated, retained in the free or protein-bound fraction of liver and muscle, or catabolized. This study revealed that a decrease in P/E ratio resulted in lower amino acid evacuation (p <0.05), contributing to a more efficient amino acid uptake. Results indicate that amino acids are retained as protein in the liver and not only temporarily available in the free pool. The amount of free amino acids retained in the muscle of LowP/E fed fish was significantly higher than in HighP/E fish ( p < 0.05 ) due to a simultaneous higher retention of lysine and methionine, without affecting the overall protein retention. Methionine catabolism was significantly lower than lysine or protein independently of the P/E ratio ( p < 0.05 ), reinforcing that this amino acid is preferentially spared for metabolic functions and not used as energy source. In contrast, increasing the dietary P/E ratio decreased lysine catabolism and increased its availability for growth. The bioavailability and metabolism of individual amino acids should be considered when optimizing P/E ratios in diets for gilthead seabream juveniles. Formulating diets with optimum P/E ratios will improve diet utilization and fish performance.

Environmental evidence of Valencia lagoon coastal barrier stabilization from 8500 BP to Present. Climate and eustatic variations

The Albufera de Valencia is one of the largest lagoon in the Spanish Mediterranean. Two continuous borehole cores reaching depths of 8 and 14 m in the northern part of the lagoon underwent sedimentological, micropaleontological and biological study. The organic content was also analysed, and 14C radiometric dating and amino acid racemization were performed. Study of the content of benthic foraminifera and n-alkanes and alkanoic acids in the lagoon sedimentary record identified several periods.The core records showed seven different environments: alluvial; freshwater marsh; brackish marsh; brackish lagoon; brackish lagoon with marine connection, backbarrier flat, and backshore. These environments changed due to eight phases associated with the transgression and regression of the barrier system, which caused the shift from exposed environments as the backshore with washover, to the typical low-energy lagoon and marsh deposition.The paleoenvironmental evolution described above is interpreted as a response to global climate changes. The shift from an alluvial setting to a brackish lagoon is probably related to the late of Early Holocene sea level rise ending at the Holocene Climate Optimum, when the highest sea level was reached. The persistence of the brackish lagoon, with no marine connection, is probably synchronous with dry conditions in the area (Booth et al., 2005) at the time of Bond event 3 (i.e., 4.2 ka) in the North Atlantic region (Bond et al., 2001). Finally, the arrival of large amounts of sediment triggered the accretion of the barrier, also enhancing coastal progradation until the present day. These results allow an evaluation of the impact of anthropic action on the Valencia lagoon, especially since the eighteenth century, and a short- and medium-term projection of the consequences of present-day climate change.

The Community Structure and Grazing Rates of Meiobenthos in Chunsu Bay, West Coast of Korea

Min, W.-G.; Kwon, K.-G.; Rho, H.S., and Kim, D., 2018. The Community Structure and Grazing Rates of Meiobenthos in Chunsu Bay, West Coast of Korea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 401–405. Coconut Creek (Florida), ISSN 0749-0208.The community structure and grazing rates of meiobenthos was studied in Chunsu bay on west coast of Korea. To examine feeding habit of major meiofaunal groups, grazing rate of nematodes and harpacticoid copepods was measured using the isotope-tracer (3H thymidine, 14C amino acid) method at 3 stations in subtidal area and 1 station in intertidal area of Chunsu bay. Time-serial measurement of grazing rate was made to elucidate the effects of day/night and tidal cycle on diel feeding rhythm of the animals. The number of culturable bacteria fluctuated from 1.73±0.25×105 to 18.23±1.17×105 CFU/cm3 during the study period, and was highest in October. The Concentration of Chl.a in the sediment at the study site was 18.0~168.2 mg/m2 in April and 36.6~111.0 mg/m2 in October. The most abundant meiobenthos was nematodes and followed by sarcomastigophorans, harpacticoid copepods. Density of meiobenthos were 5~1632 inds./10cm2 during the study period. The grazing rates of nematode varied 0.5~57.2%/h on bacteria and 0.4~53.3%/h on microalgae at the station in tidal flat. The grazing rates of harpacticoid copepods were 0.2~14.2%/h on bacteria and 0.3~12.2%/h on benthic microalgae at the station in tidal flat. In the subtidal area, the grazing rates of nematode were 33.4~82.5%/h on bacteria and 10.3~71.5%/h on microalgae and harpacticoid copepods were 0.2~14.2%/h on bacteria and 0.3~12.2%/h on benthic microalgae.

Supplementing taurine to plant-based diets improves lipid digestive capacity and amino acid retention of Senegalese sole (Solea senegalensis) juveniles

Recent studies reported positive effects of taurine supplementation to plant protein-based diets on fish growth performance and feed conversion ratio but the mechanisms involved remain unclear. The objective of this work was to provide a first insight on the importance of taurine on dietary protein and lipid absorption and utilisation, in Senegalese sole (Solea senegalensis) juveniles fed plant-based diets. Seven practical diets were tested: a fishmeal-based diet (FM) and a plant protein-based formula (PP85) to which taurine was added in graded levels: 0.2% (TAU1), 0.3% (TAU2), 0.4% (TAU3), 0.7% (TAU4) and 1.5% (TAU5). Short-term metabolic trials were performed by tube-feeding the different experimental diets labelled with different tracers: 14C-taurine, 14C-triolein (as tracer of dietary triacylglycerol) and a mixture of 14C-amino acids. Feeding sole juveniles with the PP85 diet affected taurine metabolism, since a higher proportion of dietary taurine was directed to gallbladder and probably used for bile salt synthesis. Consistent with this, fish receiving the plant-based low taurine-content diets (PP85 and TAU1) displayed a poor triacyglycerol digestion capacity. A higher proportion of 14C-amino acids was retained in fish muscle when fed the TAU5 compared to the PP85 diet. These short-term trials suggested that taurine supplementation to a plant-based diet might be beneficial to sole performance by enhancing bile salt synthesis and triacylglycerol digestion as well as muscle amino acid retention. However, this dietary supplementation should be tested in long-term trials to verify the effect on fish growth and to assess the beneficial effects on protein and lipid metabolism suggested here. Statement of relevance in the general field of aquaculture (limited to 60 characters)Adding taurine to a plant-based diet is beneficial for sole

Pathway and sink activity for translocation of 14C absorbed as amino acids in the Pisolithus extraradical mycelium of ectomycorrhizal Pinus thunbergii seedlings

To characterize the pathway and sink activity for the translocation of amino acids and their metabolites in the extraradical mycelium (ERM) of ectomycorrhizal (ECM) symbiosis, we locally labeled a part of the ERM of Pinus thunbergii seedlings colonized by a Pisolithus isolate with [14C(U)]-l-alanine (14C-Ala) or [14C(U)]-l-glutamine (14C-Gln) and followed the 14C distribution in the ERM by autoradiography. After 14C-Ala or 14C-Gln labeling, 14C was mainly distributed in a bundle of rhizomorphs extending from the labeled part towards ECM root tips of the host, but not in thick roots or the aboveground part of the seedling. When 14C-Ala was added after seedling removal, no 14C bundle appeared in the remaining ERM. These results indicate that 14C amino acids and their metabolites are translocated unidirectionally towards the ECM root tips, where strong sink activity for amino acids is localised. 14C was also distributed diffusely over a broad region in ERM surrounding the labeled part. This result suggests that 14C amino acids and their metabolites are also translocated multidirectionally in the ERM by sink activity distributed diffusely all over the whole ERM.

Dietary glucose stimulus at larval stage modifies the carbohydrate metabolic pathway in gilthead seabream (Sparus aurata) juveniles: An in vivo approach using 14C-starch

The concept of nutritional programming was investigated in order to enhance the use of dietary carbohydrates in gilthead seabream juveniles. We assessed the long-term effects of high-glucose stimuli, exerted at the larval stage, on the growth performance, nutrient digestibility and metabolic utilization and gene expression of seabream juveniles, challenged with a high-carbohydrate intake. During early development, a group of larvae (control, CTRL) were kept under a rich-protein-lipid feeding regime whereas another group (GLU) was subjected to high-glucose stimuli, delivered intermittently over time. At juvenile stage, triplicate groups (IBW: 2.5g) from each fish nutritional background were fed a high-protein (59.4%) low-carbohydrate (2.0%) diet before being subjected to a low-protein (43.0%) high-carbohydrate (33.0%) dietary challenge for 36-days. Fish from both treatments increased by 8-fold their initial body weight, but neither growth rate, feed intake, feed and protein efficiency, nutrient retention (except lipids) nor whole-body composition were affected (P˃0.05) by fish early nutritional history. Nutrient digestibility was also similar among both groups. The metabolic fate of 14C-starch and 14C-amino acids tracers was estimated; GLU juveniles showed higher absorption of starch-derived glucose in the gut, suggesting an enhanced digestion of carbohydrates, while amino acid use was not affected. Moreover, glucose was less used for de novo synthesis of hepatic proteins and muscle glycogen from GLU fish (P<0.05). Our metabolic data suggests that the early glucose stimuli may alter carbohydrate utilization in seabream juveniles.

Quantitative Identification of Biogenic Nonextractable Pesticide Residues in Soil by (14)C-Analysis.

Quantification of nonextractable residues (NER) of pesticides in soil is feasible by use of radioactively labeled compounds, but structural information on these long-term stabilized residues is usually lacking. Microorganisms incorporate parts of the radiolabeled ((14)C-) carbon from contaminants into microbial biomass, which after cell death enters soil organic matter, thus forming biogenic nonextractable residues (bioNER). The formation of bioNER is not yet determinable in environmental fate studies due to a lack of methodology. This paper focuses on the development of a feasible analytical method to quantify proteinaceous carbon, since proteins make up the largest mass portion of bacterial cells. The test substance (14)C-bromoxynil after 56 days forms more than 70% of NER in soil. For further characterization of NER the amino acids were extracted, purified, and separated by two-dimensional thin-layer chromatography (TLC). Visualization of the (14)C-amino acids was performed by bioimaging, unambiguous identification by GC-MS and LC-MS/MS. Our analysis revealed that after 56 days of incubation about 14.5% of the (14)C-label of bromoxynil was incorporated in amino acids. Extrapolating this content based on the amount of proteins in the biomass (55%), in total about 26% of the NER is accounted for by bioNER and thus is not environmentally relevant.

Magnesium deficiency during pregnancy in mice impairs placental size and function

ObjectiveMaternal magnesium (Mg) deficiency has been associated with fetal growth restriction. Using a mouse model of maternal Mg deficiency-induced fetal growth restriction, we sought to investigate the effect of Mg deficiency on placental physiology and function. MethodsIn vivo: Pregnant Swiss Webster mice were fed either 100% of the recommended amount of Mg (control) or 10%Mg (Mg-deficient) (8 per group). Dams were euthanized on gestational day 17 and placentas were collected, weighed and assessed for Mg concentrations, as well as nutrient transporter mRNA expression. For nutrient transfer studies, control and Mg-deficient dams (6 per group) were injected with 14C-amino acids and 3H-glucose and trans-placental passage was determined. In vitro: BeWo placental cells were grown in media containing 10%Mg to 100%Mg and the effects of Mg status on cell proliferation, oxidative stress and nutrient uptake were measured. Data were analyzed by Student's t-tests comparing controls vs. Mg-deficient animals or cells. For multiple comparisons, data were analyzed by ANOVA followed by Dunnett's post hoc testing. ResultsIn vivo: Maternal Mg deficiency decreased placental Mg content, placental and fetal weights, ratio of fetal:placental weight (P < 0.05), placental Slc7a5 transporter mRNA expression and transplacental nutrient transport (P < 0.05). In vitro: Mg deficiency reduced BeWo nutrient uptake (P < 0.01) and cell proliferation (P < 0.01), and increased oxidative stress (P < 0.01). ConclusionThese findings highlight the adverse effects of maternal Mg deficiency on fetal weight and placental function, including transport and proliferation and may explain the fetal growth restriction observed with moderate Mg deficiency in mice.

Synthesis of 1,2-trans-2-acetamido-2-deoxyhomoiminosugars.

The first synthesis of 1,2-trans-homoiminosugars devised as mimics of β-D-GlcNAc and α-D-ManNAc is described. Key steps include a regioselective azidolysis of a cyclic sulfite and a β-amino alcohol skeletal rearrangement applied to a polyhydroxylated azepane. The β-D-GlcNAc derivative has been coupled to serine to deliver an iminosugar C-amino acid. The two homoiminosugars demonstrate moderate glycosidase inhibition.

95 Identification Of Likely Pathogenic Variants In Patients With Bicuspid Aortic Valve: Correlation Of Complex Genotype With A More Severe Aortic Phenotype

IntroductionThe common heritable condition of Bicuspid Aortic Valve (BAV) is phenotypically heterogeneous, with valve dysfunction and aortopathy the major complications. We report overrepresentation of rare, likely pathogenic variants in target...

Precocious germination and its regulation in embryos of triticale caryopses

Triticale var. Lasko embryos, isolated from grain gathered at milk ripeness, the beginning of wax ripeness and at full ripeness, were allowed to germinate for 48 h on agar with glucose. The highest incorporation of tritiated adenosine into polyribosomal RNA during germination was found in the ribosome fractions from embryos of grain gathered at full ripeness, lower incorporation was in preparations from embryos of milk ripe grain and the lowest in preparations from embryos of wax ripe grain. Different tendencies were observed in respect to the synthesis of ribosomal proteins. The highest incorporation of &lt;sup&gt;14&lt;/sup&gt;C-amino acids into ribosomal proteins was found in preparations of ribosome fractions from embryos of milk ripe grain, lower in preparations of embryos from fully ripe grain, the lowest in preparations of embryos from wax ripe grain. ABA (10&lt;sup&gt;-4&lt;/sup&gt; M) completely inhibited the external symptoms of germination of immature embryos, while its inhibition of the synthesis of polyribosomal RNA and ribosomal proteins was greater the more mature the embryos that were germinated. The greatest stimulation of precocious germination by exogenous BA and GA&lt;sub&gt;3&lt;/sub&gt; was demonstrated in the least mature embryos isolated from milk ripe grain. Under the influence of both stimulators, an increase of the proportion of polyribosomes in the total ribosome fraction occurred in this sample, as did a rise in the intensity of ribosomal protein synthesis. The incorporation of &lt;sup&gt;3&lt;/sup&gt;H-adenosine into polyribosomal RNA, however, was lower than in the control sample. The results obtained suggest that the regulation of precocious germination of triticale embryos by phyto-hormones is not directly related to transcription.

The effect of the plant growth retardants AMO-1618 and CCC on the synthesis of ribonucleic acids and proteins in triticale embryos during the initial phase of germination

Triticale var. Grado caryopses were subjected to imbibition and germination in the presence of the growth retardants, AMO-1618 (2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidinecarboxylate methyl chloride) and CCC (2-chloroethyl)-trimethylammonium chloride) at the following concentrations, 3 x 10&lt;sup&gt;-4&lt;/sup&gt; M and 10&lt;sup&gt;-3&lt;/sup&gt; M. These compounds exerted a very strong inhibitory effect on the initiation of germination processes, growth of embryos and the germination capacity of the caryopses. At the concentration of 10&lt;sup&gt;-3&lt;/sup&gt; M, AMO-1618 showed an especially strong effect, lowering the germination capacity of the caryopses to about 50%. It was also shown that both retardants are decidedly more effective on the germination of whole, intact caryopses than on that of isolated embryos. During the very earliest hours of germination, these retardants already inhibited RNA synthesis. The participation of the polyribosome fraction in the total ribosome fraction of embryos in the control sample after 24 hrs of germination of caryopses equalled about 70%, while in the samples treated with CCC (10&lt;sup&gt;-3&lt;/sup&gt; M)- about 57%, in the samples treated with AMO-1618 (10&lt;sup&gt;-3&lt;/sup&gt; M) about 35%,. The inhibition of incorporation of &lt;sup&gt;14&lt;/sup&gt;C-amino acids into ribosomal proteins in the polyribosome fraction was in the case of CCC about 13%, while in the samples treated with AMO-1618, about 55%. In the monosome fraction (80S), the inhibition by CCC was about 23%, whereas in the samples treated with AMO-1618 it reached around 73%. From this data it is evident that the studied retardants have a significant influence on the synthesis of ribonucleic acids as well as on ribosome proteins. These results also suggest the existance of another mechanism, aside from that of inhibition of gibberellin biosynthesis, inhibiting the growth and development of cells. The high percentage of ribosome subunits in the samples treated with CCC, in comparison with controls and samples treated with AMO-1618, points to different mechanisms by which these two compounds affect protein biosynthesis.

An evaluation of Mesodon and other larger terrestrial gastropod shells for dating late Holocene and historic alluvium in the Midwestern USA

Understanding the history of stream erosion and changes in channel morphology is important for managing and restoring unstable streams. One of the significant challenges in this type of research is establishing accurate dating of late Holocene and historic alluvium. Here we evaluate the potential of using 14C dating and amino acid racemization (AAR) to date large terrestrial gastropod shells that are often preserved within alluvial sediments. Many terrestrial gastropods incorporate old carbon from limestone or other carbonate rocks into their shells and therefore are unsuitable for radiocarbon dating. Recent studies, however, have shown that some taxa avoid this ‘limestone problem’ and can yield reliable 14C ages. In this study, we measured the 14C activity of specimens for the genera Mesodon, Ventridens, and Allogona collected live and from alluvial sequences dated independently by dendrochronology, 14C dating of wood, and/or 137Cs analyses. Mesodon zaletus contained old carbon in similar concentrations (up to ~30%) found in previous studies of other large taxa and should be avoided for 14C dating when possible. In contrast, shells of Ventridens ligera and Allogona profunda showed minimal limestone effects and therefore may be suitable for dating late Holocene alluvium. These results highlight the importance of taxonomic identification of gastropod taxa prior to their use for 14C dating and demonstrate that shell fragments that are not identifiable should be avoided. We also measured d/l ratios (n=17) of aspartic and glutamic acid from eight different taxa of terrestrial gastropods recovered from four late Holocene and historic stratigraphic sequences. Average d/l ratios of aspartic and glutamic acid from historic sediments <300years old are lower in shells from younger stratigraphic units, indicating that AAR can be used to differentiate between multiple historic stratigraphic units.

Low Mass MS/MS Fragments of Protonated Amino Acids Used for Distinction of Their 13C- Isotopomers in Metabolic Studies

Glu, Gln, Pro, and Ala are the main amino acids involved in ammonia detoxification in mosquitoes. In order to develop a tandem mass spectrometry method (MS(2)) to monitor each carbon of the above isotopically-labeled (13)C-amino acids for metabolic studies, the compositions and origins of atoms in fragments of the protonated amino acid should be first elucidated. Thus, various electrospray (ESI)-based MS(2) tools were employed to study the fragmentation of these unlabeled and isotopically-labeled amino acids and better understand their dissociation pathways. A broad range of fragments, including previously-undescribed low m/z fragments was revealed. The formulae of the fragments (from m/z 130 down to m/z 27) were confirmed by their accurate masses. The structures and conformations of the larger fragments of Glu were also explored by ion mobility mass spectrometry (IM-MS) and gas-phase hydrogen/deuterium exchange (HDX) experiments. It was found that some low m/z fragments (m/z 27-30) are common to Glu, Gln, Pro, and Ala. The origins of carbons in these small fragments are discussed and additional collision induced dissociation (CID) MS(2) fragmentation pathways are proposed for them. It was also found that small fragments (≤m/z 84) of protonated, methylated Glu, and methylated Gln are the same as those of the underivatized Glu and Gln. Taken together, the new approach of utilizing low m/z fragments can be applied to distinguish, identify, and quantify (13)C-amino acids labeled at various positions, either in the backbone or side chain.

The Use of an In Vitro-cultured Porcine Nasal Mucosa Model for the Biocompatibility Assessment of Biodegradable Magnesium

The development of an in vitro-cultured porcine nasal mucosa model is described. The model was subsequently used for the biocompatibility testing of resorbable magnesium-based implants, which are intended for use in the nasal cavity of patients with chronic rhinosinusitis (CRS). Test specimens made from either pure magnesium or titanium were incubated with the mucosal tissue for 48 hours. Afterwards, tissue viability, PGE2, IL-6 and IL-8 release, magnesium ion release, succinate dehydrogenase activity, apoptosis and 14C amino acid incorporation, were determined. The results suggested favourable biocompatibility, even in the case of rapidly-degrading pure magnesium. However, presumed effects on protein synthesis and apoptosis could not be confirmed.

Effects of salicylic acid on protein content and 14C-amino acid incorporation into proteins of pea roots

Pea (Pisum sativum L.) root treatment with salicylic acid (SA) changed the content of some proteins and incorporation of 14C-amino acids into proteins. The analysis of changes in these indices allowed us to subdivide all proteins into the four groups: (1) most abundant SA-independent proteins; (2) SA-dependent proteins, which content and 14C-amino acids incorporation both increased; (3) SA-dependent proteins, which content and 14C-amino acids incorporation both decreased; and (4) SA-dependent proteins, which content was not essentially changed (referred earlier to SA-independent proteins) but 14C-amino acids incorporation into these proteins was strongly suppressed. It is very likely that proteolysis of the proteins referred to the fourth group is very low and even a strong inhibition of their synthesis (incorporation of 14C-amino acids) does not result in the substantial decrease in their contents. Some SA-dependent proteins were identified by means of modern methods of proteomics: phosphoglyceromutase, S-adenosylmethionine synthase 3, enolase, chalcone isomerase, nucleoside diphosphate kinase 1, and tioredoxin h.

Duration of induced thermal tolerance and tissue-specific expression of hsp/hsc70 in the eastern oyster, Crassostrea virginica and the pacific oyster, Crassostrea gigas

We compared thermotolerance and the heat shock response of Pacific oysters ( Crassostrea gigas) and Eastern oysters ( Crassostrea virginica), both are very valuable commercial species. The former were much more resistant to high temperature, reaching maximum induced thermotolerance (IT) by 2 days after a sublethal heat shock (SHS) and lasting for at least 3 weeks, a possible record for the duration of IT in any animal. Two constitutive isoforms of 77 and 72kD, and an inducible 69kD protein were detected in both oysters, their amounts and time course after SHS varied, depending on the tissue examined. Synthesis of these three proteins in gills (ctenidia) of C. gigas was reduced to control levels within 2 days after SHS as judged by 14 C-amino acid incorporation. However, western blotting showed that the levels of these stress proteins in tissues from heat shocked C. gigas remained higher than those in controls, suggesting a reduction in protein degradation after SHS. Variable patterns of these three isoforms were detected in gills, mantle, adductor muscle and digestive gland before and after SHS. The general features described for C. gigas tissues were also observed in adductor muscle, gill and mantle of C. virginica, although some differences were also noted. We discuss the difficulties and importance associated with the use of commercially-available antibodies in the study of these stress proteins in oysters.

In Vitro 14C-Labeled Amino Acid Uptake Changes and Surface Abnormalities in the Colon after 1,2-Dimethylhydrazine—Induced Experimental Carcinogenesis: Protection by Zinc

The present study explored the regulatory role of zinc on the in vitro uptake of ¹⁴C-glucose and ¹⁴C-labeled amino acids and on colonic surface abnormalities after 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. Rats were segregated into four groups: control, DMH-treated, zinc-treated, and DMH + zinc-treated. Colon carcinogenesis was induced through weekly subcutaneous injections of DMH (30 mg/kg body weight) for 16 weeks. Zinc (in the form of zinc sulfate) was given to rats at a dose level of 227 mg/L in their drinking water. DMH treatment caused a significant decrease in the activities of disaccharidases (sucrase, lactase, and maltase), but a significant increase in the activity of alkaline phosphatase. In vitro uptake of ¹⁴C-D-glucose and the amino acids ¹⁴C-glycine, ¹⁴C-alanine, ¹⁴C-lysine, and ¹⁴C-leucine were significantly higher in the colons of DMH-treated rats. Zinc supplementation of DMH-treated rats resulted in regulating the altered intestinal enzyme activities and in vitro uptake of ¹⁴C-amino acids and ¹⁴C-glucose. Scanning electron microscopy revealed drastic alterations in the colon surface morphology after DMH treatment, which were restored after zinc supplementation. Our results confirm a beneficial effect of zinc against DMH-induced alterations in the colons of rats.