Effect of Arsenic Exposure on Early Eye Development in Zebrafish (Danio rerio)

Arsenic is a metalloid that contaminates drinking water supplies worldwide. Due to concerns for human health, the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA) have established a safe level in drinking water of ≤ 10 ppb. Arsenic has been shown to have carcinogenic effects in humans at high and low doses. Chronic exposure may result in dermal conditions such as hyperkeratosis and hyperpigmentation. Recently, arsenic exposure has also been linked to lower IQ values in children. The effect of arsenic on neurogenesis, specifically eye development, has not been widely explored. This study aimed to examine the effect of environmentally relevant concentrations of arsenic on early eye development by morphological and molecular analysis. The zebrafish (Danio rerio) was chosen to model the impacts of arsenic on retinogenesis because of its similarities to human eye development both structurally and genetically. The effect of arsenic exposure on the gross morphology of the eye and tissue development via histology were examined at three larval stages. It was found that exposure to arsenic has an effect on eye morphology resulting in a significant increase in eye diameter at 14 dpf (days post fertilization) relative to control under all treatment conditions. This was coupled with a trend in thinning of the retinal pigmented epithelium (RPE) layer in fish exposed to 500 ppb arsenic. The impacts of arsenic exposure on gene expression were analyzed following treatments of 10, 50, and 500 ppb from 1 – 72 hpf (hours post fertilization). Molecular analysis of genes associated with eye development was investigated by RT-qPCR at 32 and 48 hpf. RT-qPCR results revealed differential expression of Pax6a, Pax2a, Ngn1, Sox2, and Shha relative to control. Specifically Pax6a, Pax2a, and Sox2 are found to be important in the formation of the RPE. Proper formation of the RPE is necessary for growth of the sclera which, in turn, is responsible for maintaining the shape of the eye. Although we observed a thinning of the RPE we also noted an overall increase in eye size of 14 dpf zebrafish. This could potentially be explained by the disruption of gene expression under arsenic exposure during critical time points in early eye development

Assessment of RNAi-induced silencing in banana (Musa spp.)

In plants, RNA- based gene silencing mediated by small RNAs functions at the transcriptional or post-transcriptional level to negatively regulate target genes, repetitive sequences, viral RNAs and/or transposon elements. Post-transcriptional gene silencing (PTGS) or the RNA interference (RNAi) approach has been achieved in a wide range of plant species for inhibiting the expression of target genes by generating double-stranded RNA (dsRNA). However, to our knowledge, successful RNAi-application to knock-down endogenous genes has not been reported in the important staple food crop banana

Bias and consistency in time delay estimation methods: case of the double quasar HE 1104-1805

We present a short re-evaluation of a recently published time delay estimate for the gravitational lens system HE 1104-1805 with emphasis on important methodological aspects: bias of the statistics, inconsistency of the methods and use of the purposeful selection of data points(or so-called "cleaning") at the preprocessing stage. We show how the inadequate use of simple analysis methods can lead to too strong conclusions. Our analysis shows that there are indications for the time delay in HE 1104-1805 to be between -0.9 and -0.7 years, but still with a large uncertainty.Comment: 5 pages, 5 figures, accepted as a Letter to the Editor in A&

Fire emission heights in the climate system - Part 1: Global plume height patterns simulated by ECHAM6-HAM2

We use the global circulation model ECHAM6 extended by the aerosol module HAM2 to simulate global patterns in wildfire emission heights. Prescribed plume heights in ECHAM6 are replaced by an implementation of a simple, semi-empirical plume height parametrization. In a first step, the global performance of the plume height parametrization is evaluated for plumes reported in the Multiangle Imaging Spectroradiometer (MISR) Plume Height Project (MPHP) data set. Our results show that the parametrization simulates a largely reasonable global distribution of plume heights. While the modeled global mean plume height (1411 ± 646 m) is in good agreement with the observed mean (1382 ± 702 m), the upper and lower tails of the plume height distribution tend to be slightly underrepresented. Furthermore, we compare plume heights simulated by the simple parametrization to a more complex, analytical plume model. Major differences in global plume height distributions are found for the lowest 1.5 km, but reasonable agreement is observed for higher plumes. In a second step, fire radiative power (FRP) as reported in the global fire assimilation system (GFAS) is used to simulate plume heights for observed fires globally for the period 2005–2011. The global fraction of simulated daytime plumes injecting emissions into the free troposphere (FT) ranges from 3.7 ± 0.7 to 5.2 ± 1.0 %. This range is comparable to results from observational studies, but it is much lower than results for prescribed plume heights in the ECHAM6-HAM2 standard setup. Nevertheless, occasionally deep emission injections exceeding 5–7 km in height are simulated for intense fires and favorable meteorological conditions. The application of a prescribed diurnal cycle in FRP turns out to be of minor importance. For a hypothetical doubling in FRP, moderate changes in plume heights of 100–400 m are simulated. These small changes indicate that a potential future increase in fire intensity will only slightly impact the emission heights on a global scale

Three photometric methods tested on ground-based data of Q 2237+0305

The Einstein Cross, Q~2237+0305, has been photometrically observed in four bands on two successive nights at NOT (La Palma, Spain) in October 1995. Three independent algorithms have been used to analyse the data: an automatic image decomposition technique, a CLEAN algorithm and the new MCS deconvolution code. The photometric and astrometric results obtained with the three methods are presented. No photometric variations were found in the four quasar images. Comparison of the photometry from the three techniques shows that both systematic and random errors affect each method. When the seeing is worse than 1.0", the errors from the automatic image decomposition technique and the Clean algorithm tend to be large (0.04-0.1 magnitudes) while the deconvolution code still gives accurate results (1{sigma} error below 0.04) even for frames with seeing as bad as 1.7". Reddening is observed in the quasar images and is found to be compatible with either extinction from the lensing galaxy or colour dependent microlensing. The photometric accuracy depends on the light distribution used to model the lensing galaxy. In particular, using a numerical galaxy model, as done with the MCS algorithm, makes the method less seeing dependent. Another advantage of using a numerical model is that eventual non-homogeneous structures in the galaxy can be modeled. Finally, we propose an observational strategy for a future photometric monitoring of the Einstein Cross.Comment: 9 pages, accepted for publication in A&

Effects of an experimental resource pulse on the macrofaunal assemblage inhabiting seagrass macrophytodetritus

Physical disturbances and resource pulses are major structuring drivers of terrestrial and aquatic ecosystems. The accumulations of exported dead leaves from the Neptune grass, Posidonia oceanica (L.) Delile are ephemeral and highly dynamic detrital habitats offering food sources and shelter for vagile macrofauna community. These habitats are frequently subject to wind and storms which can add “new” detrital material to previous accumulations; these can be defined as resource pulses and could potentially impact the associated macrofauna. This study assesses the impact of an experimental resource pulse on the macrofauna associated with exported P. oceanica litter accumulations. The experimental design consisted of two pulse treatments (the addition of dead leaves with and without the associated fauna), and two controls (one procedural, and one total control), where the added material was left underwater for 14 days. Invertebrates then present in the sampled detritus were all identified and counted. Our data suggest that the responses of these invertebrates to resource pulses present intermediate characteristics between aquatic and terrestrial ecosystems responses. Inputting a moderate amount of dead P. oceanica leaves into experimental mesocosms had a non-negligible impact and rapidly affected the macrofauna community. Specialist detritivores species were boosted while herbivore/detritivore species dramatically decreased. Predators also showed a modest but significant density increase, demonstrating the fast propagation of the pulse response throughout the entire community and through several trophic levels. Strict hypoxia-tolerant species were also only observed in the treated mesocosms, indicating the strong influence of resource pulses on physico-chemical conditions occurring inside litter accumulations

Promoting Regulatory Prediction

It is essential for environmental protection that private actors be able to anticipate government regulation. If, for instance, the Biden Administration is planning to tighten regulations of greenhouse gas emissions, it is imperative that private companies anticipate this regulatory change now, not a few years from now after they have constructed even more coal- and gas-fired power plants. Those additional power plants will mean more irreversible greenhouse gases, and these plants can be politically challenging to shutter once built. The point is general to private actors making decisions in the shadow of potential government regulation. Better information about future government actions is thus critical for the benefit of both private actors and society at large. In this Article, we consider market-based and non-market-based means by which to generate information about future government action. We find no perfect answer. We consider three market-based solutions—prediction markets, the use of equity markets to hedge against future government action, and machine-learning and predictive technologies—and three government-based solutions—greater transparency, the development of intellectual property rights in predictive information, and prediction-forcing regulation, which is regulation that requires private actors to make public predictions about future government action. None of these is a panacea. The market-based solutions founder on the limitations and thinness of markets. Government-based solutions come with significant structural downsides related to the division of authority among different levels of government (federal versus state versus local) and different branches of government at each level (executive versus legislative). We conclude that prediction-forcing regulation may be the most promising avenue, though it too is likely not a full solution

Promoting Regulatory Prediction

It is essential for environmental protection that private actors be able to anticipate government regulation. If, for instance, the Biden Administration is planning to tighten regulations of greenhouse gas emissions, it is imperative that private companies anticipate this regulatory change now, not a few years from now after they have constructed even more coal- and gas-fired power plants. Those additional power plants will mean more irreversible greenhouse gases, and these plants can be politically challenging to shutter once built. The point is general to private actors making decisions in the shadow of potential government regulation. Better information about future government actions is thus critical for the benefit of both private actors and society at large. In this Article, we consider market-based and non-market-based means by which to generate information about future government action. We find no perfect answer. We consider three market-based solutions—prediction markets, the use of equity markets to hedge against future government action, and machine-learning and predictive technologies—and three government-based solutions—greater transparency, the development of intellectual property rights in predictive information, and prediction-forcing regulation, which is regulation that requires private actors to make public predictions about future government action. None of these is a panacea. The market-based solutions founder on the limitations and thinness of markets. Government-based solutions come with significant structural downsides related to the division of authority among different levels of government (federal versus state versus local) and different branches of government at each level (executive versus legislative). We conclude that prediction-forcing regulation may be the most promising avenue, though it too is likely not a full solution

Assessing Tolerance to Heavy-Metal Stress in Arabidopsis thaliana Seedlings

The deposited book chapter is a post-print version and has been submitted to peer review.The deposited book chapter version contains attached the supplementary materials within the pdf.This publication hasn't any creative commons license associated.The deposited book chapter is part of the book series: "Environmental Responses in Plants: Methods and Protocols" (pp.197-208) published by Springer.Heavy-metal soil contamination is one of the major abiotic stress factors that, by negatively affecting plant growth and development, severely limit agricultural productivity worldwide. Plants have evolved various tolerance and detoxification strategies in order to cope with heavy-metal toxicity while ensuring adequate supply of essential micronutrients at the whole-plant as well as cellular levels. Genetic studies in the model plant Arabidopsis thaliana have been instrumental in elucidating such mechanisms. The root assay constitutes a very powerful and simple method to assess heavy-metal stress tolerance in Arabidopsis seedlings. It allows the simultaneous determination of all the standard growth parameters affected by heavy-metal stress (primary root elongation, lateral root development, shoot biomass, and chlorophyll content) in a single experiment. Additionally, this protocol emphasizes the tips and tricks that become particularly useful when quantifying subtle alterations in tolerance to a given heavy-metal stress, when simultaneously pursuing a large number of plant lines, or when testing sensitivity to a wide range of heavy metals for a single line.Fundação para a Ciência e a Tecnologia grants: (EXPL/AGR-PRO/1013/2013, SFRH/BPD/44640/2008); GREEN-it "Bioresources for Sustainability": (UID/Multi/04551/2013).info:eu-repo/semantics/publishedVersio

Aktivitas Sitotoksik Dari Ekstrak Bintang Ular (Ophiomastix Annulosa) Terhadap Perkembangan Awal Embrio Bulu Babi (Tripneustes Gratilla)

Penelitian di bidang alam bahari telah berkembang ditandai dengan ditemukannya substansi-substansi seperti sitotoksik, antimikroba, antifungi dan sebagainya yang dibutuhkan dalam penyediaan bahan-bahan farmasi. Penelitian ini bertujuan untuk mendeteksi ada tidaknya substansi sititoksik pada bintang ular Ophimastix annulosa dan menelusuri keberadaan senyawanya. Sampel diekstraksi dengan pelarut metanol, kemudian dipartisi menggunakan pelarut etil asetat, heksan dan kloroform. Tiap fraksi diuji pada sel telur bulu babi (Tripneustes gratilla) sebelum dan sesudah difertilisasi. Hasil pengamatan menunjukkan bahwa ekstrak metanolik O. annulosa dan ketiga fraksi (etil asetat, heksan dan kloroform) memiliki substans sitotoksik. keempat fraksi yang diuji mampu menghambat perkembangan sel telur dan embrio bulu babi. fraksi kloroform menunjukkan aktivitas sitotoksik tertinggi dibandingkan ketiga fraksi lainnya sehingga perlu dilakukan pemurnian lanjut untuk menemukan senyawa murni