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At least 199 records · Page 11Linked to original sources
PubMed2003

Stable carbon and nitrogen isotope signatures indicate recovery of marine biota from sewage pollution at Moa Point, New Zealand.

Stable carbon and nitrogen isotopes have been used to assess sewage contamination of a sewage outfall, discharging milli-screened effluent into Moa Point Bay, New Zealand, and monitor the recovery of flora and fauna after the outfall's closure. An initial study characterising the extent of the discharge and the effects on seaweed (Ulva lactuca L.), blue mussels (Mytilus galloprovincialis) and limpets (Cellana denticulata) from the area, showed effects of the sewage discharge on flora and fauna were localised within in the bay. The immediate area surrounding the discharge area was found to contain limited biodiversity, with an abundance of Ulva lactuca, a bright green lettuce-like seaweed, typically found in areas with high nutrient input, limpets and small blue mussels. The nitrogen isotopic signature (delta15N) is shown to be a good tracer of sewage pollution in seaweed and associated grazers (i.e. limpets) as a result of the increased contribution of urea and ammonia to seawater nitrogen derived from the effluent. The carbon isotopic signature (delta13C) is suggested as a more appropriate sewage tracer for mussels, which filter feed the effluent's particulate organic matter from the water. Lower carbon:nitrogen ratios were found in Ulva lactuca sampled from around the outfall region compared to uncontaminated control sites. However carbon:nitrogen ratios do not vary significantly amongst shellfish species. After closure, monitoring continued for 9 months and showed that the carbon and nitrogen isotopic signatures of algae (Ulva lactuca L.) returned to similar control site levels within 3 months. Limpet and blue mussels (Cellana denticulata and Mytilus galloprovincialis) showed slower recovery times than the Ulva lactuca, with detectable levels of the sewage-derived carbon and nitrogen remaining in the animal's tissue for up to 9 months.

Animals↗
PubMed2004

Multiple genetic processes result in heterogeneous rates of evolution within the major cluster disease resistance genes in lettuce.

Resistance Gene Candidate2 (RGC2) genes belong to a large, highly duplicated family of nucleotide binding site-leucine rich repeat (NBS-LRR) encoding disease resistance genes located at a single locus in lettuce (Lactuca sativa). To investigate the genetic events occurring during the evolution of this locus, approximately 1.5- to 2-kb 3' fragments of 126 RGC2 genes from seven genotypes were sequenced from three species of Lactuca, and 107 additional RGC2 sequences were obtained from 40 wild accessions of Lactuca spp. The copy number of RGC2 genes varied from 12 to 32 per genome in the seven genotypes studied extensively. LRR number varied from 40 to 47; most of this variation had resulted from 13 events duplicating two to five LRRs because of unequal crossing-over within or between RGC2 genes at one of two recombination hot spots. Two types of RGC2 genes (Type I and Type II) were initially distinguished based on the pattern of sequence identities between their 3' regions. The existence of two types of RGC2 genes was further supported by intron similarities, the frequency of sequence exchange, and their prevalence in natural populations. Type I genes are extensive chimeras caused by frequent sequence exchanges. Frequent sequence exchanges between Type I genes homogenized intron sequences, but not coding sequences, and obscured allelic/orthologous relationships. Sequencing of Type I genes from additional wild accessions confirmed the high frequency of sequence exchange and the presence of numerous chimeric RGC2 genes in nature. Unlike Type I genes, Type II genes exhibited infrequent sequence exchange between paralogous sequences. Type II genes from different genotype/species within the genus Lactuca showed obvious allelic/orthologous relationships. Trans-specific polymorphism was observed for different groups of orthologs, suggesting balancing selection. Unequal crossover, insertion/deletion, and point mutation events were distributed unequally through the gene. Different evolutionary forces have impacted different parts of the LRR.

Alleles↗
PubMed2003

Development of seaweed biomass as a biosorbent for metal ions .

Three seaweed species collected from Hong Kong waters were screened for their adsorption abilities for Cu2+, Ni2+ and Zn2+ and Ulva lactuca having the highest metal ion removal capacity (RC) was chosen for further study. Effects of algal biomass and medium pH on the metal ions RC of Ulva lactuca were determined and optimized. Under the optimal conditions of the corresponding metal ions, the algal Cu2+, Ni2+ and Zn2+ RCs were 65.54, 21.00 and 49.54 mg/g, respectively. The presence of other cations and anions affected the metal ions adsorption by the seaweed. The effect was dependent on the between the target metal ions and other cations/anions. The kinetic study revealed that the adsorption of Cu2+, Ni2+ and Zn2+ by Ulva lactuca fitted the Langmuir isotherm. Comparing with 0.1 M HCl, citric acid, thiourea, EDTA and HNO3, 0.1 M H2SO4 efficiently recovered close to 100% adsorbed metal ions from Ulva lactuca. In three successive adsorption-desorption cycles, reduction in metal ion RCs was found in the second and third cycles, but almost all adsorbed metal ion could be recovered.

Adsorption↗
PubMed2004

Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus.

This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

Animals↗
PubMed2006

Turkish freshwater and marine macrophyte extracts show in vitro antiprotozoal activity and inhibit FabI, a key enzyme of Plasmodium falciparum fatty acid biosynthesis.

The ethanolic extracts of a number of Turkish freshwater macrophytes (Potamogeton perfoliatus, Ranunculus tricophyllus and Cladophora glomerata) and marine macroalgae (Dictyota dichotoma, Halopteris scoparia, Posidonia oceanica, Scinaia furcellata, Sargassum natans and Ulva lactuca) were assayed for their in vitro antiprotozoal activity. Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and Plasmodium falciparum were used as test organisms. The cytotoxicity of the extracts was also assessed against primary rat skeletal myoblasts (L6 cells). Whereas none of the extracts were active against T. cruzi, all crude extracts displayed appreciable trypanocidal activity against T. brucei rhodesiense, with S. natans being the most active one (IC(50) 7.4microg/ml). Except for the marine alga H. scoparia, all extracts also possessed leishmanicidal potential. The best antileishmanial activity was exerted by U. lactuca and P. oceanica (IC(50)'s 5.9 and 8.0microg/ml, respectively). Five extracts that demonstrated inhibitory activity towards P. falciparum (IC(50)'s 18.1-48.8microg/ml) were simultaneously assayed against FabI, a crucial enzyme of the fatty acid system of P. falciparum, to find out whether FabI was their target. The extracts of C. glomerata and U. lactuca efficiently inhibited the FabI enzyme with IC(50) values of 1.0 and 4.0microg/ml, respectively. None of the extracts were cytotoxic towards mammalian L6 cells. This work reports for the first time antiprotozoal activity of some Turkish marine and freshwater algae, as well as a target-based antiplasmodial screening for the identification of P. falciparum FabI inhibitors from aquatic and marine macrophytes.

Animals↗
PubMed1990

A mollicute (mycoplasma) DNA repair enzyme: purification and characterization of uracil-DNA glycosylase.

The DNA repair enzyme uracil-DNA glycosylase from Mycoplasma lactucae (831-C4) was purified 1,657-fold by using affinity chromatography and chromatofocusing techniques. The only substrate for the enzyme was DNA that contained uracil residues, and the Km of the enzyme was 1.05 +/- 0.12 microM for dUMP containing DNA. The product of the reaction was uracil, and it acted as a noncompetitive inhibitor of the uracil-DNA glycosylase with a Ki of 5.2 mM. The activity of the enzyme was insensitive to Mg2+, Mn2+, Zn2+, Ca2+, and Co2+ over the concentration range tested, and the activity was not inhibited by EDTA. The enzyme activity exhibited a biphasic response to monovalent cations and to polyamines. The enzyme had a pI of 6.4 and existed as a nonspherical monomeric protein with a molecular weight of 28,500 +/- 1,200. The uracil-DNA glycosylase from M. lactucae was inhibited by the uracil-DNA glycosylase inhibitor from bacteriophage PBS-2, but the amount of inhibitor required for 50% inhibition of the mycoplasmal enzyme was 2.2 and 8 times greater than that required to cause 50% inhibition of the uracil-DNA glycosylases from Escherichia coli and Bacillus subtilis, respectively. Previous studies have reported that some mollicutes lack uracil-DNA glycosylase activity, and the results of this study demonstrate that the uracil-DNA glycosylase from M. lactucae has a higher Km for uracil-containing DNA than those of the glycosylases of other procaryotic organisms. Thus, the low G + C content of the DNA from some mollicutes and the A.T-biased mutation pressure observed in these organisms may be related to their decreased capacity to remove uracil residues from DNA.

Base Composition↗
PubMed2004

Functional sulfur amino acid production and seawater remediation system by sterile Ulva sp. (Chlorophyta).

Sterile Ulva, which is a macroalga, has the potential to grow stably; therefore, this seaweed is expected to be an efficient resource of functional food containing various nutrients such as sulfur amino acids, proteins, carbohydrates, and minerals. Ulva latuca was selected from the "Marine Park" in Tokyo Bay, and its growth rate (g-dry/[m2.d]) was measured using model reactors located on the land or on the surface of the sea at Yokohama. The growth rate of U. lactuca was recorded to be approx 20 g-dry/(m2.d), which is estimated to be 10 times greater than that in a natural field in the Marine Park. In addition, this growth rate was higher than that of conventional crops such as corn and rice on a farm or paddy. These data led us to newly design and propose a floating type of labor-efficient U. lactuca production system. d-Cysteinolic acid, which is included in U. lactuca as a major sulfur amino acid, inhibited the Fenton reaction, resulting in suppression of hydroxyl radical production and singlet oxygen. Addition of the sulfur amino acid (1 microM) to HepG2 cells markedly decreased the intracellular triglyceride level. Hence, this proposed facility also has the potential for industrial production of a valuable resource for the primary prevention of lifestyle-related diseases using enriched or eutrophied seawater.

Amino Acids, Sulfur↗
PubMed2002

Overview of results from the WaterTox intercalibration and environmental testing phase II program: Part 1, statistical analysis of blind sample testing.

There is an urgent need to evaluate the presence of toxicants in waters used for human consumption and to develop strategies to reduce and prevent their contamination. The International Development Research Centre undertook an intercalibration project to develop and validate a battery of bioassays for toxicity testing of water samples. The project was carried out in two phases by research institutions from eight countries that formed the WaterTox network. Results for the first phase were reported in the special September 2000 issue of Environmental Toxicology. Phase II involved toxicity screening tests of environmental and blind samples (chemical solutions of unknown composition to participating laboratories) using the following battery: Daphnia magna, Hydra attenuata, seed root inhibition with Lactuca sativa, and Selenastrum capricornutum. This battery was also used to assess potential toxicity in concentrated (10x) water samples. Results are presented for a set of six blind samples sent to the participating laboratories over a 1-year period. Analyses were performed for each bioassay to evaluate variations among laboratories of responses to negative controls, violations of test quality control criteria, false positive responses induced by sample concentration, and variability within and between labs of responses to toxic samples. Analyses of the data from all bioassays and labs provided comparisons of false positive rates (based on blind negative samples), test sensitivities to a metal or organic toxicant, and interlaboratory test variability. Results indicate that the battery was reliable in detecting toxicity when present. However, some false positives were identified with a concentrated soft-water sample and with the Lactuca and Hydra (sublethal end-point) tests. Probabilities of detecting false positives for individual and combined toxic responses of the four bioassays are presented. Overall, interlaboratory comparisons indicate a good reliability of the battery.

Animals↗
PubMed2002

A novel nucleolar biomarker in plant and animal cells for assessment of substance cytotoxicity.

The cytotoxicity of three substances (mercury(II), metolachlor, and 4-nitroquinoline-N-oxide) was assessed with a set of nucleolar parameters: the average number of nucleoli, the average volume of a single nucleolus, and the proportion of cells with heteromorphic-paired nucleoli (PNhet). Their toxic impact was studied on cells of animal and plant test organisms: onion (Allium cepa), lettuce (Lactuca sativa), and hydra (Hydra attenuata). In general, at concentrations near IC/LC(50) the three chemicals produced similar cytogenetic effects after 30-360 min of contact. For instance, in plant cells (Allium cepa and Lactuca sativa) the toxicants increased the percentage of cells with PNhet, decreased the volume of single nucleoli, and exerted no significant impact on the nucleolar number. In animal cells (Hydra attenuata), they reduced the size of nucleoli, produced no effect on the number of nucleoli, but decreased the share of cells with PNhet. Also, the chemicals affected the cells of the three test organisms to different degrees. Thus, the effectiveness of our approach of using nucleolar biomarker (use of the proposed set of parameters and time schedule of several determinations in the first hours of toxicant contact, etc.) as a means of assessing cytotoxicity was confirmed.

4-Nitroquinoline-1-oxide↗