Electrochemical monitoring of malondialdehyde biomarker in biological samples via electropolymerized amino acid/chitosan nanocomposite

This study reports on the electropolymerization of a low toxic and biocompatible nanopolymer with entitle poly arginine‐graphene quantum dots‐chitosan (PARG‐GQDs‐CS) as a novel strategy for surface modification of glassy carbon surface and preparation of a new interface for measurement of malondialdehyde (MDA) in exhaled breath condensate. Electrochemical deposition, as a well‐controlled synthesis procedure, has been used for subsequently layer‐by‐layer preparation of GQDs‐CS nanostructures on a PARG prepolymerized on the surface of glassy carbon electrode using cyclic voltammetry techniques in the regime of ?1.5 to 2 V. The modified electrode appeared as an effective electroactivity for detection of MDA by using cyclic voltammetry, linear sweep voltammetry, and differential pulse voltammetry. The prepared modified electrode demonstrated a noticeably good activity for electrooxidation of MDA than PARG. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between the excellent properties of PARG and semiconducting polymer, GQDs as high density of edge plane sites and subtle electronic characteristics and unique properties of CS such as excellent film‐forming ability, high permeability, good adhesion, nontoxicity, cheapness, and a susceptibility to chemical modification. The prepared sensor showed 1 oxidation processes for MDA at potentials about 1 V with a low limit of quantification 5.94 nM. Finally, application of new sensor for determination of MDA in exhaled breath condensate was suited. In general, the simultaneous attachment of GQDs and CS to structure of poly amino acids provides new opportunities within the personal healthcare.     

Design and synthesis of new antitumor agents with the 1,7-epoxycyclononane framework. Study of their anticancer action mechanism by a model compound

This article describes the design, synthesis and biological evaluation of a new family of antitumor agents having the 1,7-epoxycyclononane framework. We have developed a versatile synthetic methodology that allows the preparation of a chemical library with structural diversity and in good yield. The synthetic methodology has been scaled up to the multigram level and can be developed in an enantioselective fashion. The study in vitro of a model compound, in front of the cancer cell lines HL-60 and MCF-7, showed a growth inhibitory effect better than that of cisplatin. The observation of cancer cells by fluorescence microscopy showed the presence of apoptotic bodies and a degradation of microtubules. The study of cell cycle and mechanism of death of cancer cells by flow cytometry indicates that the cell cycle arrested at the G₀/G₁ phase and that the cells died by apoptosis preferably over necrosis. A high percentage of apoptotic cells at the subG₀/G₁ level was observed. This indicates that our model compound does not behave as an antimitotic agent like nocodazole, used as a reference, which arrests the cell cycle at G₂/M phase. The interaction of anticancer agents with DNA molecules was evaluated by atomic force microscopy, circular dichroism and electrophoresis on agarose gel. The results indicate that the model compound has not DNA as a target molecule. The in silico study of the model compound showed a potential good oral bioavailability.     

Creating a bubble…and an understanding of scientific practices

The use of creativity in science practices is many times lost on secondary students. Creativity is seen as something central to the arts and humanities, but tangential at best in the sciences. However, an examination of many great scientific discoveries and the work of everyday contemporary scientists shows the depth and breadth of the use of creativity in the scientific process. Creating a Bubble is an activity that can be used in a secondary classroom to help students understand not only the importance of creativity in science practices, but also the role of communication, the open-endedness of scientific endeavors, and the use of others’ ideas. Students are given a straw, Styrofoam cup, and dish soap and asked to create a big bubble consistently. At first, the techniques that are used produce many small bubbles. Eventually, someone asks how big a big bubble is. Armed with the knowledge that a big bubble is at least 33?cm (13-inches) in diameter, students become very creative in the techniques they try. They learn from each other and eventually are successful in their quest. Frustration and persistence are also key ingredients along their journey.     

Gravity is a pull! Exploring forces and motion with English learners

English learners (ELs) benefit from inquiry-based science instruction that includes explicit attention to language learning goals. The purpose of this article is to share a third-grade unit on forces and motion which integrates science inquiry and writing in science notebooks with the goal of developing ELs' engagement in science, conceptual understanding, and academic language and literacy skills. We demonstrate how to engage diverse students' background knowledge and use classroom activities and discussion to create bridges between everyday and academic language. We utilize excerpts from Peter, Lucia, and Andrea's science notebooks to explore and highlight how teachers can use this resource as a means of communicating science, during instruction. Through these EL students' journals, we discuss the importance of developing language goals at the word, sentence, and discourse level while promoting and supporting ELs' use of the language of science.     

Butterflies & wild bees: biology teachers’ PCK development through citizen science*

Citizen science is a rapidly growing emerging field in science and it is gaining importance in education. Therefore, this study was conducted to document the pedagogical content knowledge (PCK) of biology teachers who participated in a citizen science project involving observation of wild bees and identification of butterflies. In this paper, knowledge about how these biological methods can be taught to students is presented. After two years in the project, four teachers were interviewed and their PCK was captured in the form of content representations (CoRes) and Pedagogical and Professional-Experience Repertoires (PaP-eRs). These results can help future citizen science projects to link their activities to the school curriculum. But not only success can be reported: although one of the project team’s aims was to make the Nature of Science accessible to the teachers and students in the course of the project, the teachers did not take this aspect into account. This paper discusses the possible reasons and proposes various strategies for improving citizen science in the context of school biology learning.     

The effect of teaching the nature of science on students’ acceptance and understanding of evolution: myth or reality?

The results of studies of the nature of science (NOS) as a factor that enhances students’ understanding of evolution have been inconclusive. Therefore, the main purpose of this study was to test the role of NOS instruction in enhancing students’ learning about evolution. We used a quasi-experimental design with pre- and post-tests to investigate the impact of teaching evolution with and without NOS in two classes with 15–16-year-old students, who were randomly assigned to these two classes. To measure their understanding of NOS and their acceptance and understanding of evolution, we used three different instruments that have been shown to generate reliable and valid inferences in comparable populations. The main results of this study were that, in the class in which the teaching of evolution included NOS instruction, the students’ understanding of NOS and their acceptance of evolution significantly improved. However, irrespective of the use of NOS instruction, both classes increased their understanding of evolution. These results support the claim that NOS instruction may influence students’ acceptance of evolution but not their understanding of evolution and natural selection.     

Changes in habitat suitability influence non‐breeding distribution of waterbirds in central Europe

Waterbird species have different requirements with respect to their non‐breeding areas, aiming to survive and gain condition during the non‐breeding period. Selection of non‐breeding areas could change over time and space driven by climate change and species habitat requirements. To help explain the mechanism shaping non‐breeding area selection, we provide site‐specific analyses of distributional changes in wintering waterbirds in central Europe, located at the centre of their flyways. We use wintering waterbirds as a highly dynamic model group monitored over a long‐time scale of 50 years (1966–2015). We identified species habitat requirements and changes in habitat use at the level of 733 individual non‐breeding (specifically wintering) sites for 12 waterbird species using citizen‐science monitoring data. We calculated site‐specific mean numbers and estimated site‐specific trends in numbers. The site‐specific approach revealed a general effect of mean winter temperature of site (seven of 12 species), wetland type (all species) and land cover (all species) on site‐specific numbers. We found increasing site‐specific trends in numbers in the northern and/or eastern part of the study area (Mute Swan Cygnus olor, Eurasian Teal Anas crecca, Common Pochard Aythya ferina, Great Cormorant Phalacrocorax carbo and Eurasian Coot Fulica atra). Common Merganser Mergus merganser, Great Cormorant, Grey Heron Ardea cinerea, Common Pochard, Eurasian Coot and Common Moorhen Galinulla chloropus increased their site‐specific numbers on standing industrial waters with traditionally low fish stock. The site‐specific dynamics of bird numbers helped us to identify general preference for sites reducing winter harshness (warmer areas, running waters and more wetlands in the site vicinity), as well as indicating climate‐driven changes in spatial use of wintering sites (northern/north‐eastern range changes and changes in preference for industrial waters). This fine‐scale (site‐specific) approach can reveal large‐scale range and distribution shifts driven by climate and environmental changes regardless of the availability of large‐scale datasets.     

An untold story in biology: the historical continuity of evolutionary ideas of Muslim scholars from the 8th century to Darwin’s time

Textbooks on the history of biology and evolutionary thought do not mention the evolutionary ideas of Muslim scholars before Darwin’s time. This is part of a trend in the West to minimise the contributions of non-Western scientists to biology, human anatomy and evolutionary biology. Therefore, this paper focuses on the contributions of pre-Darwinian Muslim scholars to the history of evolutionary thought. Our review of texts from a wide range of historical times, and written in various languages, reveals that there were in fact several Muslim scholars who postulated evolutionary ideas, some with remarkable similarities to Darwin’s theory. These ideas included the adaptation and survival of the fittest, a specific origin of humans from apes/monkeys, the notion of evolutionary constraints, the occurrence of extinctions within taxa and hereditary variability. Moreover, while both the scientific community and the broader public generally base their knowledge on Western textbooks, several parts of the Muslim world have indicated an overall rejection of biological–including human–evolution. Therefore, to improve historical accuracy and create a better understanding of scientific history, the world’s diverse civilisations and their philosophies, this untold story should be widely disseminated to the scientific community and the general public.     

On the origin of coding sequences from random open reading frames

Summary The size distribution of 411 randomly selected mammalian exons was investigated. This distribution was found to be unimodal with a frequency maximum of 120 bp. Detailed analysis of the distribution demonstrated that larger exons (>150 bp) have a high goodness of fit to the size distribution of open reading frames (ORFs) in a random sequence, i.e., (61/64)^t in which t is the number of triplets. Based on this observation, the general character of the total exon size distribution suggested that this could be defined by a theoretical distribution by superimposing a sigmoid function on the ORF generating function, i.e., (61/64)^t×f_s(t)×E in which f_s(t) is a sigmoid function and E is a constant. We tested this distribution for fitness to the exon distribution using two sigmoid functions. f_s(t)=(t) and f_s(t)=Be^kt/1+Be^kt. In both cases a very high goodness of fit was attained. It is concluded that exons have been generated from ORFs in random sequences, that ORFs larger than 150 bp have been selected, irrespective of size, as exons, and that a lower size limit exists below which the probability of an ORF being selected as an exon is very low. These results provide evidence at the molecular level to support the ideas that (1) larger exons have been selected from random ORFs without primary correlation to structural or functional properties at the protein level, (2) there exists a restriction on smaller ORFs to be selected as exons, and (3) the interrupted coding sequences found in eukaryotes represent the ancient form of gene organization that existed prior to the divergence of prokaryotes and eukaryotes.