Arsenic and cadmium in the marine macroalgae (Porphyra yezoensis and Laminaria Japonica) — forms and concentrations

Abstract

Total arsenic, inorganic arsenic (iAs), total cadmium concentrations and chemical forms of cadmium were analysed in Porphyra yezoensis collected monthly from January to April in 2011 and in Laminaria Japonica collected monthly from March to July in 2010. Results showed that total As concentrations in P. yezoensis were much lower than those in L. Japonica. The iAs concentrations in both macroalgae were all below the maximum limit according to the legislation in China, while total Cd concentrations in all samples of P. yezoensis exceeded the maximum limit. The percentage of iAs to total As decreased in both macroalgae with the time. The results provide important information showing that both macroalgae are able to metabolise inorganic arsenic to organic forms. Thus both macroalgae have evolved arsenic resistance which is linked to the capability of metabolising toxic inorganic arsenic. In addition, the results suggest that the transformation rate of arsenate to organic arsenic in both algae increases with the growth and metabolic rate that increase with elevated environmental temperature. Temperatures rise from January to April in Jiangsu province and from March to July in Liaoning Province. Most Cd was associated with pectates and protein (extractable by 1 M NaCl) in both algae, and only a small percentage of the Cd was inorganic (extractable by 80% ethanol). The Cd chemical forms have no obvious relationship with the time in both algae.     

The Influence of Physical Habitat,Pyrethroids, and Metals on Benthic Community Condition in an Urban and Residential Stream in California

This study was designed to characterize benthic communities and physical habitat in both an urban (Kirker Creek) and residential (Pleasant Grove Creek) stream in California in late spring of 2006 and 2007. Concurrent water quality evaluations, physical sediment parameters, pyrethroids, bulk metals, and SEM/AVS ratios were also measured during both years of this study. The relationship of various benthic metrics to physical habitat metrics, pyrethroids, and metals was evaluated for each stream using stepwise multiple linear regressions with both years combined for each stream, as well as both years and both streams combined, to increase the statistical power for determining significant relationships. Physical habitat was determined to be poor in each stream during both years of sampling. More than 100 benthic taxa were reported annually for both streams based on 2006 and 2007 sampling. A significant result from the stepwise regression analysis combining data for 2 years across both streams is that when habitat metrics and to a lesser degree metals are considered in the statistical models pyrethroids do not display any significant relationships to the benthic metrics. In summary, it is apparent from this analysis that the health of benthic communities in both streams is primarily affected by habitat metrics.     

Utilization of ketone bodies by chick brain and spinal cord during embryonic and postnatal development

Lipid synthesis from acetoacetate and 3-hydroxybutyrate was studied in chick embryo from 15 to 21 days and in chick neonate from 1 to 21 days. Embryonic spinal cord showed higher ability than brain to incorporate acetoacetate into total lipids, although a sharp decrease was found at hatching. 3-Hydroxybutyrate incorporation into total lipids was also higher in spinal cord than in brain, especially during the embryonic period. Phospholipids were the main lipids formed in both tissues from both precursors. An appreciable percentage of radioactivity was also recovered as free cholesterol, especially during the embryonic phase. The developmental patterns of amino acid synthesis from acetoacetate and 3-hydroxybutyrate were similar in both tissues: a clear increase after hatching was followed by a decrease at day 4 of neonatal life. Acetoacetate was a better substrate for amino acid synthesis than 3-hydroxybutyrate during the embryonic development in both tissues. Oxidation of both precursors to CO₂ strongly decreased between 15 and 21 days of embryonic development both in brain and spinal cord.     

Soft-electron beam and gamma-radiation sensitivity and DNA damage in phosphine-resistant and -susceptible strains of Rhyzopertha dominica

The soft-electron beam (low-energy electrons) and gamma-radiation sensitivities of phosphine-resistant (PHR) and -susceptible (PHS) strains of adults lesser grain borer Rhyzopertha dominica (F.) were studied, with particular reference to DNA damage assessed using single-cell electrophoresis (comet assay). Results showed that mortality in adult R. dominica varied significantly between both PHR and PHS strains. Adults of the PHR strain were found to be more tolerant toward soft-electron and gamma radiation than adults of the PHS strain. Studies on the longevity of strains showed that mean survival time and dose rate were highly correlated with both strains and treatments. Results also showed that adults of the PHR strain lived longer than adults of PHS strain for both treatments. Radiation sensitivity indices, however, decreased as radiation dose increased in both strains. Analysis of DNA damage, after 40- and 160-Gy gamma radiation, was carried out using cells obtained from both strains. Gamma-irradiated adults of both strains showed typical DNA fragmentation, compared with cells from nonirradiated adults, which showed more intact DNA. Investigations using the comet assay showed that tail length, moment, olive-tail moment, percentage of tail DNA, and percentage of DNA damage were all greater in the PHS strain compared with the PHR strain and the control insects. Results also showed that DNA damage remained at a constant level for up to 24 h after irradiation. The results have been discussed in relation to the observed strain differences in radiation sensitivity and resistance to phosphine.     

Dogfish metallothionein--I. Purification and characterization and comparison with rat metallothionein

A low-molecular weight metal-binding protein has been found in the liver of the dogfish (Scyliorhinus canicula) in both control and cadmium-treated animals and in both male and female animals. This protein is present as Zn, Cu-protein in control and as Cd, Zn, Cu-protein cadmium-treated (both water and i.p. administration) animals. This hepatic protein was characterized as metallothionein from several properties related to mammalian metallothionein. A different response to cadmium administration between sexes is suggested.     

Rapid and sensitive HPLC assay for simultaneous determination of procaine and para-aminobenzoic acid from human and rat liver tissue extracts

A sensitive and rapid high-performance liquid chromatography method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA) from human and rat liver tissue extracts. The method has been validated according to ICH guidelines in terms of selectivity, linearity, lower limit of detection, lower limit of quantitation, accuracy, precision and recovery from human and rat liver tissue extracts. Chromatography was carried out on a Discovery C(18) column using 10mM ammonium acetate at pH 4.0 and acetonitrile as mobile phase. Retention times for procaine and PABA were 6.6 and 5.3 min, respectively. Linearity for each calibration curve in both tissue extracts was observed across a range from 10 microM to 750 microM for procaine and PABA. The lower limit of detection for both procaine and PABA was 5 microM and the lower limit of quantitation was 10 microM in both tissue extracts. The intra- and inter-day relative standard deviations (R.S.D.) for both procaine and PABA were <6%. Recoveries of procaine and PABA from human and rat liver tissue extracts were determined by two different methods with a single-step protein precipitation technique being employed in both methods. Recoveries for both procaine and PABA were greater than 80% from both human and rat liver tissue extracts.     

Binding and degradation of heterodimeric substrates by ClpAP and ClpXP

ClpA and ClpX function both as molecular chaperones and as the regulatory components of ClpAP and ClpXP proteases, respectively. ClpA and ClpX bind substrate proteins through specific recognition signals, catalyze ATP-dependent protein unfolding of the substrate, and when in complexes with ClpP translocate the unfolded polypeptide into the cavity of the ClpP peptidase for degradation. To examine the mechanism of interaction of ClpAP with dimeric substrates, single round binding and degradation experiments were performed, revealing that ClpAP degraded both subunits of a RepA homodimer in one cycle of binding. Furthermore, ClpAP was able to degrade both protomers of a RepA heterodimer in which only one subunit contained the ClpA recognition signal. In contrast, ClpXP degraded both subunits of a dimeric substrate only when both protomers contained a recognition signal. These data suggest that ClpAP and ClpXP may recognize and bind substrates in significantly different ways.     

Interconversion of putrescine,spermidine and spermine in goldfish and rat retina

Labelled putrescine is converted to spermidine and spermine in the retina of both the goldfish and of the rat, but the bulk remains as putrescine and spermidine in the goldfish retina whereas the bulk is present as spermine in the rat retina. Labelled spermidine is converted to spermine and to putrescine in the retina of both species, most remaining as spermidine in the goldfish retina whereas most is converted to spermine in the rat retina. Labelled spermine is converted to both spermidine and putrescine in the retina of both species with a greater conversion in the goldfish retina than in the rat retina. These results provide direct evidence of the interconversion of putrescine, spermidine and spermine in neural tissue from both fish and mammals and suggest that spermine should not be regarded solely as an end-product of putrescine metabolism but also as a source of spermidine and putrescine.The pattern of distribution of putrescine and the polyamines, spermidine and spermine, in goldfish retina is the reverse of that in rat retina: Putrescine is the most abundant in goldfish retina whereas spermine is most abundant in rat retina suggesting that the individual polyamines are of different importance in the two species.     

c-Cbl and Cbl-b Act Redundantly to Protect Osteoclasts from Apoptosis and to Displace HDAC6 from β-Tubulin,Stabilizing Microtubules and Podosomes

c-Cbl and Cbl-b are highly conserved adaptor proteins that participate in integrin signaling, regulating cytoskeletal organization, motility, and bone resorption. Deletion of both c-Cbl and Cbl-b in mice leads to embryonic lethality, indicating that the two proteins perform essential redundant functions. To examine the redundant actions of c-Cbl and Cbl-b in osteoclasts, we depleted c-Cbl in Cbl-b^−/− osteoclasts by using a short hairpin RNA. Depleting both Cbl proteins disrupted both the podosome belt and the microtubule network and decreased bone-resorbing activity. Stabilizing the microtubules with paclitaxel or inhibiting histone deacetylase 6 (HDAC6), which destabilizes microtubules by deacetylating β-tubulin, protected both the microtubule network and the podosome belt. Examination of the mechanism involved demonstrated that the conserved four-helix bundle of c-Cbl''s tyrosine kinase binding domain bound to β-tubulin, and both c-Cbl and Cbl-b displaced HDAC6. In addition to the effects on microtubules and the podosome belt, depleting both Cbls significantly increased the levels of the proapoptotic protein Bim and apoptosis relative to the levels induced by eliminating either protein alone. Thus, both c-Cbl and Cbl-b promote bone resorption via the stabilization of microtubules, allowing the formation of the podosome belt in osteoclasts, and by promoting osteoclast survival.     

Purification and characterization of adhesive exopolysaccharides from Pseudomonas putida and Pseudomonas fluorescens

In this study, the adhesive exopolysaccharides of strains of Pseudomonas putida and P. fluorescens, both isolated from freshwater epilithic communities, were examined with regard to their chemical composition, biosynthesis, and their role in adhesion. Electron microscopy showed that both strains were enrobed in fibrous glycocalyces and that these structures were involved in attachment of the cells to a solid surface and as structural matrices in the microcolony mode of growth. In batch culture experiments most of the extracellular polysaccharide of both strains was found to be soluble in the growth medium rather than being associated with bacterial cells. Exopolysaccharide was synthesized during all phases of growth, but when growth was limited by exhaustion of the carbon source, exopolysaccharide synthesis ceased whereas exopolysaccharide synthesis continued for some time after cessation of growth in nitrogen-limited cultures. Exopolysaccharide from both strains was isolated and purified. Pseudomonas putida synthesized an exopolysaccharide composed of glucose, galactose, and pyruvate in a ratio of 1:1:1; the P. fluorescens polymer contained glucose, galactose, and pyruvate in a ratio of 1:1:0.5, respectively. Polymers from both strains were acetylated to a variable degree.     

Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal

Dams are known to impact river channels and ecosystems, both during their lifetime and in their decommissioning. In this study, we applied a before-after-control-impact design associated with two small dam removals to investigate abiotic and biotic recovery trajectories from both the elimination of the press disturbance associated with the presence of dams and the introduction of a pulse disturbance associated with removal of dams. The two case studies represent different geomorphic and ecological conditions that we expected to represent low and high sensitivities to the pulse disturbance of dam removal: the 4 m tall, gravel-filled Brownsville Dam on the wadeable Calapooia River and the 12.5 m tall, sand and gravel-filled Savage Rapids Dam on the largely non-wadeable Rogue River. We evaluated both geomorphic and ecological responses annually for two years post removal, and asked if functional traits of the macroinvertebrate assemblages provided more persistent signals of ecological disturbance than taxonomically defined assemblages over the period of study. Results indicate that: 1) the presence of the dams constituted a strong ecological press disturbance to the near-downstream reaches on both rivers, despite the fact that both rivers passed unregulated flow and sediment during the high flow season; 2) ecological recovery from this press disturbance occurred within the year following the restoration action of dam removal, whereas signals of geomorphic disturbance from the pulse of released sediment persisted two years post-removal, and 3) the strength of the press disturbance and the rapid ecological recovery were detected regardless of whether recovery was assessed by taxonomic or functional assemblages and for both case studies, in spite of their different geomorphic settings.     

Expression of nidogens in rat uterus and embryo during decidualization and implantation

The purpose of this study was to demonstrate the expression of nidogen-1 and nidogen-2 and their possible role in decidualization and implantation events during early pregnancy in rats. The tissue samples were examined from pregnant animals between gestational days 1-8 using immunocytochemistry. The uterine luminal epithelium, the glandular epithelium, and the myometrial smooth muscle cells stained strongly from gestational days 1-8 with both nidogen antibodies. At day 4 the decidual reaction areas began to appear in the stromal matrix and immunostaining of both nidogens revealed that the basement membrane of the surface epithelium was discontinuous. The differentiation of stromal cells into decidual cells was seen at gestational day 5 and both nidogens were weakly expressed in the decidualizing cells. At day 6, nidogen-2 immunoreactivity was higher in the primary decidual cells close to the embryo than nidogen-1, and during development of the decidual tissue both nidogens appeared in the endometrial stromal cells. At day 7, while expression of both nidogens declined in the primary decidual cells, their expression was markedly observed in the secondary decidual cells close to the myometrium. At day 8, expression of both nidogens was also observed to increase in the primary decidual cells. While nidogen-2 expression was seen in the parietal endoderm and primary ectoderm of the rat embryos at this developmental stage, nidogen-1 expression was only detected in the parietal endoderm. These results indicate that nidogen-1 and nidogen-2 could play important roles during embryogenesis, decidualization, and implantation in the endometrium of rat uterus.     

Cloning of Escherichia coli lacZ and lacY genes and their expression in Gluconobacter oxydans and Acetobacter liquefaciens

An efficient transformation protocol for Gluconobacter oxydans and Acetobacter liquefaciens strains was developed by preparation of electrocompetent cells grown on yeast extract-ethanol medium. Plasmid pBBR122 was used as broad-host-range vector to clone the Escherichia coli lacZY genes in G. oxydans and A. liquefaciens. Although both lac genes were functionally expressed in both acetic acid bacteria, only a few transformants were able to grow on lactose. However, this ability strictly depended on the presence of a plasmid expressing both lac genes. Mutations in the plasmids and/or in the chromosome were excluded as the cause of growth ability on lactose.     

The Helicobacter pylori flaA1 and wbpB genes control lipopolysaccharide and flagellum synthesis and function

flaA1 and wbpB are conserved genes with unknown biological function in Helicobacter pylori. Since both genes are predicted to be involved in lipopolysaccharide (LPS) biosynthesis, flagellum assembly, or protein glycosylation, they could play an important role in the pathogenesis of H. pylori. To determine their biological role, both genes were disrupted in strain NCTC 11637. Both mutants exhibited altered LPS, with loss of most O-antigen and core modification, and increased sensitivity to sodium dodecyl sulfate compared to wild-type bacteria. These defects could be complemented in a gene-specific manner. Also, flaA1 could complement these defects in the wbpB mutant, suggesting a potential redundancy of the reductase activity encoded by both genes. Both mutants were nonmotile, although the wbpB mutant still produced flagella. The defect in the flagellum functionality of this mutant was not due to a defect in flagellin glycosylation since flagellins from wild-type strain NCTC 11637 were shown not to be glycosylated. The flaA1 mutant produced flagellins but no flagellum. Overall, the similar phenotypes observed for both mutants and the complementation of the wbpB mutant by flaA1 suggest that both genes belong to the same biosynthesis pathway. The data also suggest that flaA1 and wbpB are at the interface between several pathways that govern the expression of different virulence factors. We propose that FlaA1 and WbpB synthesize sugar derivatives dedicated to the glycosylation of proteins which are involved in LPS and flagellum production and that glycosylation regulates the activity of these proteins.     

Biodegradation and metabolites of 2-methylquinoline by acclimated activated sludge under aerobic and denitrifying conditions

2-Methylquinoline is a common organic contaminant in environment. Its degradation in wastewater treatment system has not been fully explored. In this study, batch experiments were conducted to investigate the biodegradation of 2-methylquinoline by activated sludge under both aerobic and denitrifying conditions. The results showed that 2-methylquinoline was degraded under both conditions, but the degradation under aerobic condition was significantly faster than that under denitrifying condition. Total organic carbon (TOC) residues were detected in the final effluent under both conditions, indicating the formation of recalcitrant metabolites. Further analysis identified 1,2,3,4-tetrahydro-2-methylquinoline, N,N-diethyl-benzenamine, and 4-ethyl-benzenamine as common metabolites under both conditions. 4-Butyl-benzenamine and 2,6-diethyl-benzenamine were additional metabolites under the aerobic condition, whereas 2-methyl-4-quinolinol was exclusive to the denitrifying condition. Most of these metabolites were further degraded during the treatment process. 1,2,3,4-Tetrahydro-2-methylquinoline, however, remained in the final effluent under both conditions, implying its persistence in the environment. It can be concluded that 2-methylquinoline undergoes the similar degradation pathway under both treatment conditions.     

Circadian feeding and locomotor rhythms in pigeons and house sparrows.

Feeding and locomotor activities were measured simultaneously in homing pigeons (Columba livia) and house sparrows (Passer domesticus). Feeding, as well as locomotor activity, was found to be regulated by a circadian clock in both of these species. Implantation of melatonin-filled capsules or exposure to constant light abolished feeding and locomotor rhythms in both species. Removal of the pineal gland from pigeons did not abolish either rhythm, whereas pinealectomy abolished both feeding and locomotor rhythms in house sparrows. Although feeding rhythms were generally more robust than locomotor rhythms in both of these species, different feeding and locomotor free-running periods were not observed within any individual pigeon or house sparrow. These results are consistent with the hypothesis that each of these species has a single pacemaker that regulates the timing of feeding and locomotor activity, but they do not rule out the possibility that separate clocks regulate these behaviors.     

The toxic effect of lead on seed germination, growth, chlorophyll and protein contents of wheat and lens.

Lead is a heavy metal which is believed to be toxic when present in excessive amount. Excess Pb in Triticum sativum and Lens esculanta alters several physiological and biochemical processes in both species. Seed germination of both species grown on soaked filter paper with Pb (NO3)2 was highly inhibited (about 60% at 20 mM Pb (NO3)2). Results obtained from measurement of lead content in the roots and shoots of both species indicated that most of the lead accumulated in the roots of both species with a lower degree within the shoots. Lead uptake by both species whether grown in perlite medium or on filter paper soaked with Pb (NO3)2, was correlated with lead concentration. These results indicate a passive process of lead translocation. These results also show that lead inhibits the growth of both plant species, but root growth inhibition was more pronounced than shoot growth inhibition at different lead concentration. Total chlorophyll content was found to be decreased in both species after treatment with Pb (NO3)2. Total protein content in the seedlings, as our results have indicated, was found to be increased with increasing lead concentration in both species.     

Assimilation and allocation of carbon and nitrogen of thermal and nonthermal Agrostis species in response to high soil temperature

We studied whether changes in the assimilation and allocation of carbon and nitrogen are associated with plant tolerance to high soil temperatures. Two Agrostis species, thermal Agrostis scabra, a species adapted to high-temperature soils in geothermal areas in Yellowstone National Park (USA), and two cultivars of a cool-season species, Agrostis stolonifera, L-93 and Penncross, were exposed to soil temperatures of 37 or 20 degrees C, while shoots were exposed to 20 degrees C. Net photosynthesis rate, photochemical efficiency, NO(3) (-)-assimilation rate and root viability decreased with increasing soil temperatures in both species. However, the decreases were less pronounced for A. scabra than for both A. stolonifera cultivars. Carbon investment in growth of plants exposed to 37 degrees C decreased more dramatically in both A. stolonifera cultivars than in A. scabra. Nitrogen allocation to shoots was greater in A. scabra than in both creeping bentgrass cultivars at 37 degrees C soil temperature. Our results demonstrate that plant tolerance to high soil temperature is related to efficient expenditure and adjustment of C- and N-allocation patterns between growth and respiration.     

Plasmodium berghei and Eperythrozoon coccoides: Antibody and immunoglobulin synthesis in germfree and and conventional mice simultaneously infected

The immune response to Eperythrozoon coccoides and the malaria parasite Plasmodium berghei was evaluated in germfree (GF) and conventionally reared (CV) mice infected with both parasites. Following infection, the mice showed significant changes in the levels of the immunoglobulins IgM, 7Sγin1, 7Sγ2a, and 7Sγ2b, but no detectable changes in IgA. Increases in immunoglobulin levels were first observed in GF mice, but by the twelth day both GF and CV mice had comparable levels. 7Sγ2a globulin had a bimodal distribution in both groups of mice which probably was due to heterogeneity in the allotype of this immunoglobulin. IgM levels closely paralleled the antibody responses to P. berghei suggesting that most of the antibody to this parasite was IgM. Relatively low levels of antibody to both parasites, in comparison to the large immunoglobulin response, were detected in GF and CV mice. The possible causes for the low titers are discussed.