Glyphosate concentrations in global freshwaters: are aquatic organisms at risk?

Environmental Science and Pollution Research - Glyphosate is the most used herbicide worldwide. Many studies have reported glyphosate risks to aquatic organisms of different trophic levels....     

Environmental radiological impact associated with non-uranium mining industries: a proposal for screening criteria

Niobium, phosphate, coal and gold mining facilities have been selected as case studies with the aim of identifying possible sources of radiological impact during and after cessation of industrial operations. The results have shown that acid drainage, as well as chemical processing of mineral ores, constitute relevant impact indicators for present-day and future scenarios. The possible use of solid wastes abandoned at the end of the operations represents a long-term radiological concern. Therefore, it is necessary that Brazilian legislation for environmental licensing be revised taking into account the potential environmental and radiological impacts caused by these industries and establishing remedial procedures for waste storage areas in the existing sites. The indicators developed and procedures carried out can be used in screening for decisions on the adoption of regulatory requirements for practices at such types of installations.     

Enzymatic transformation and binding of labeled 2,4,6-trinitrotoluene to humic substances during an anaerobic/aerobic incubation

Organic pollutants are degraded in soil and simultaneously nonextractable residues are formed. However, proof is lacking that this fixation has a detoxifying effect. We investigated the transformation and binding of 2,4,6-trinitrotoluene (TNT) with catechol or soil humic acid as cosubstrates. Carbon-14-labeled TNT and its reaction products were quantified by radiocounting; extractable compounds were identified by high performance liquid chromatography (HPLC). Bound and extractable residues of 15N-labeled TNT and metabolites were studied by 15N nuclear magnetic resonance spectroscopy (15N NMR). Since TNT is not easily transformed under oxidizing conditions an anaerobic/aerobic treatment was used. Anaerobic microorganisms from cow manure were used to reduce TNT during the anaerobic phase and subsequently, a laccase from Trametes villosa was used in the aerobic phase to oxidatively couple the metabolites to humic matter. Seventy-four percent of TNT was immobilized with catechol as cosubstrate, but only 25% with humic acid. With catechol the main extractable component was TNT, while with humic acid it was mostly the metabolite 4-aminodinitrotoluene. For both co-substrates, the spectra of immobilized metabolites obtained by solid-state 15N-cross polarization magic angle spinning (CPMAS) NMR spectroscopy showed signals in the chemical shift region for protonated aromatic amino compounds. However, in the presence of catechol, an additional signal from nonextractable nitro groups was found, which could represent sequestered TNT. The partially reduced metabolites of TNT that formed nonextractable residues in humic acid are not likely to be remobilized easily and are thus regarded as detoxified.     

一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。     

Preimplantation genetic diagnosis for familial amyloidotic polyneuropathy (FAP)

Preimplantation genetic diagnosis (PGD) was developed more than a decade ago to offer an alternative to prenatal diagnosis for couples at risk of transmitting an inherited disease to their offspring. Portuguese-type familial amyloidotic polyneuropathy (FAP type I), is an autosomal dominant disease presenting an inherited mutation in the gene encoding the plasma protein transthyretin (TTR). We here report the first protocol for single-cell detection of the Met30 mutation in FAP type I and its application to PGD. A nested PCR reaction for exon 2 of the TTR gene was developed. The PCR product was then analysed by restriction enzyme analysis and SSCP allowing the detection of the point mutation. Ten clinical cycles were performed in seven couples. From the 93 metaphase II (MII) injected oocytes, 82 were normally fertilized and 78 were biopsied. A positive signal in the nested PCR reaction was obtained in 61 blastomeres, corresponding to a DNA amplification efficiency of 78.2%. No allele dropout (ADO) or contamination were detected. A biochemical pregnancy was obtained in three cases and a clinical pregnancy in one couple is actually in normal evolution. Copyright © 2001 John Wiley & Sons, Ltd.     

The Impact of Brown-Headed Cowbird Parasitism on Populations of the White-Crowned Sparrow

Brown-headed Cowbirds, Molothrus ater , are brood parasites on many species of North American Passerines. Cowbird parasitism is frequently cited as a contributing factor in the decline of United States passerine populations, based on three lines of evidence. First, range expansion and population increases by Cowbirds in this century are dramatic and well documented. Second, increasing rates of parasitism have been discovered in a variety of host species populations. Finally, direct negative effects of parasitism on certain vulnerable species notably Kirtland's Warbler, Dendroica kirtlandii , have been demonstrated. It remains unproven, however, that Cowbirds have significant negative effects on more abundant and widely-distributed hosts.
We report here on the impact of Cowbird parasitism on populations of Nuttall's White-crowned Sparrow, Zonotrichia leucophrys nuttalli , in the San Francisco Bay Area. This widespread songbird is now subject to a 40–50% rate of parasitism in San Francisco, an increase from 5% only 15 years ago. Using known mortality and fecundity values, we calculate that this population of White-crowns cannot maintain its numbers when the parasitism rate exceeds approximately 20%. Present levels of parasitism thus appear to threaten the longevity survival of this adaptable Songbird in the San Francisco Bay Area.     

Ecological restoration as a strategy for mitigating and adapting to climate change: lessons and challenges from Brazil

Climate change is a global phenomenon that affects biophysical systems and human well-being. The Paris Agreement of the United Nations Framework Convention on Climate Change entered into force in 2016 with the objective of strengthening the global response to climate change by keeping global temperature rise this century well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 °C. The agreement requires all Parties to submit their “nationally determined contributions” (NDCs) and to strengthen these efforts in the years ahead. Reducing carbon emissions from deforestation and forest degradation is an important strategy for mitigating climate change, particularly in developing countries with large forests. Extensive tropical forest loss and degradation have increased awareness at the international level of the need to undertake large-scale ecological restoration, highlighting the need to identify cases in which restoration strategies can contribute to mitigation and adaptation. Here we consider Brazil as a case study to evaluate the benefits and challenges of implementing large-scale restoration programs in developing countries. The Brazilian NDC included the target of restoring and reforesting 12 million hectares of forests for multiple uses by 2030. Restoration of native vegetation is one of the foundations of sustainable rural development in Brazil and should consider multiple purposes, from biodiversity and ecosystem services conservation to social and economic development. However, ecological restoration still presents substantial challenges for tropical and mega-diverse countries, including the need to develop plans that are technically and financially feasible, as well as public policies and monitoring instruments that can assess effectiveness. The planning, execution, and monitoring of restoration efforts strongly depend on the context and the diagnosis of the area with respect to reference ecosystems (e.g., forests, savannas, grasslands, wetlands). In addition, poor integration of climate change policies at the national and subnational levels and with other sectorial policies constrains the large-scale implementation of restoration programs. The case of Brazil shows that slowing deforestation is possible; however, this analysis highlights the need for increased national commitment and international support for actions that require large-scale transformations of the forest sector regarding ecosystem restoration efforts. Scaling up the ambitions and actions of the Paris Agreement implies the need for a global framework that recognizes landscape restoration as a cost-effective nature-based solution and that supports countries in addressing their remaining needs, challenges, and barriers.

     

The costs of intersexuality: a crustacean perspective

Increasing concerns over rising intersexuality in the animal kingdom and the ability of certain chemicals to disrupt the endocrine system have demanded a better understanding of the costs associated with such conditions. Whilst intersexuality appears relatively widespread throughout gonochoristic crustaceans, i.e. those crustacean species with two separate sexes, the fitness costs have rarely been reported. Through comparable investigation of normal and intersex specimens of the highly abundant marine/estuarine amphipod Echinogammarus marinus (Leach) these fitness costs were determined. Measurements taken to assess fitness costs included fecundity, fertility and embryonic development, maturation period, and any morphological deformities that might result in reduced pairing success. Results from this study suggest that intersex E. marinus suffer from reduced fecundity and fertility, and mature at a larger size than normal specimens. These fitness costs can also, to a certain extent, be related to the degree of intersexuality. It is suggested that the increased size and morphological abnormalities observed in intersexes may result in reduced pairing success. Investigations into intersex organisms, i.e. those organisms with known dysfunctional endocrine systems, and the costs associated with such conditions, should aid researchers in assessing effects at the population and community level.Communicated by J.P. Thorpe, Port Erin     

Preponderance of a few diatom species among the highly diverse microphytoplankton assemblages in the Bay of Bengal

The microphytoplankton assemblages were studied from water samples collected at eight discrete depths in the top 120 m at five central (open ocean) and four western (shelf/slope region) locations in the Bay of Bengal. The Bay is a low-productive warm pool regime with poor inorganic nutrient inputs to its intensely stratified surface layer despite the very large riverine influx. In addition, the prolonged cloud cover has an adverse effect on the top 25–40 m, on primary production, chlorophyll concentration and phytoplankton assemblages. Microphytoplankton were the most abundant in the northern area of the Bay. A total of 153 phytoplankton species were identified during this study. The most abundant species (at least 1,800 individual cells belonging to a given species or ≥2% of the total counts of identified specimens) during this study were: Thalassiothrix longissima, Thalassiothrix fauenfeldii, Rhizosolenia styliformis, Nitzschia angularis, Thalassionema nitzschioides, Coscinodiscus radiatus, Chaetoceros eibenii, Skeletonema costatum, Coscinodiscus concinnus and Chaetoceros coarctatus. Similarly, there were 20 moderately abundant (≥0.5 but <2%) species. Thirty-three of the least abundant species (<0.5%) occurred at one station. Diatom species, T. fauenfeldii and T. longissima were ubiquitous in the study area. The exclusive occurrence of S. costatum in the northernmost stations suggests that it proliferates only in the low-salinity regions with adequate silica from the land inputs. Abundance of pennate diatoms was higher in the open Bay compared to that of centric diatoms in the more productive northern locations and the western Bay. There appears to be a basic difference between near shore flora and offshore flora. This first analysis of phytoplankton assemblages from the offshore Bay suggests that while there is predominance of only a few species, the Bay harbors very diverse diatom communities that seem to be syntrophic, non-competitive and co-habiting in the generally low nutrient, stratified surface waters.     

Euglena gracilis as a model for the study of Cu and Zn toxicity and accumulation in eukaryotic cells

We have observed the effect of copper and zinc on the biology of Euglena gracilis. The cells displayed different sensitivities to these metals, as the apparent LC₅₀ for Cu²⁺ was 0.22 mM, and for Zn²⁺ it was 0.88 mM. While Zn²⁺ was able to increase cell proliferation even at 0.1 mM, the minimal CuCl₂ concentration tested (0.02 mM) was sufficient to impair cell division. Higher concentrations of these metals not only inhibited cell division in a concentration-dependent manner, but also interfered with the metabolism of E. gracilis. A higher accumulation of proteins and lipids per cell was observed at the DI₅₀ concentration for metal-treated cells. These results suggest that the test concentration of both metals leads to a failure in completing cell division. Ultrastructural analysis indicated a chloroplast disorganization in copper-treated cells, as well as the presence of electron dense granules with different shapes and sizes inside vacuoles. Microanalysis of these granules indicated an accumulation of copper, thus suggesting a detoxification role played by the vacuoles. These results indicate that E. gracilis is an efficient biological model for the study of metal poisoning in eukaryotic cells. They also indicate that copper and zinc (copper being more poisonous) had an overall toxic effect on E. gracilis and that part of the effect can be ascribed to defects in the structure of chloroplast membranes.