5-methylcytosine (5mC) in DNA plays an important role in gene expression, genomic imprinting, and suppression of transposable elements. 5mC can be converted to 5-hydroxymethylcytosine (5hmC) by the Tet (ten eleven translocation) proteins. Here, we show that, in addition to 5hmC, the Tet proteins can generate 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) from 5mC in an enzymatic activity–dependent manner. Furthermore, we reveal the presence of 5fC and 5caC in genomic DNA of mouse embryonic stem cells and mouse organs. The genomic content of 5hmC, 5fC, and 5caC can be increased or reduced through overexpression or depletion of Tet proteins. Thus, we identify two previously unknown cytosine derivatives in genomic DNA as the products of Tet proteins. Our study raises the possibility that DNA demethylation may occur through Tet-catalyzed oxidation followed by decarboxylation.

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Tet proteins can convert 5-methylcytosine to 5-formylcytosine and 5-carboxylcytosine

This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments in the area, with particular emphasis on applications. The types of cellulose nanofibres covered are those extracted from plants by acid hydrolysis (nanowhiskers), mechanical treatment and those that occur naturally (tunicate nanowhiskers) or under culturing conditions (bacterial cellulose nanofibrils). Research highlighted in the article are the use of cellulose nanowhiskers for shape memory nanocomposites, analysis of the interfacial properties of cellulose nanowhisker and nanofibril-based composites using Raman spectroscopy, switchable interfaces that mimic sea cucumbers, polymerisation from the surface of cellulose nanowhiskers by atom transfer radical polymerisation and ring opening polymerisation, and methods to analyse the dispersion of nanowhiskers. The applications and new advances covered in this review are the use of cellulose nanofibres to reinforce adhesives, to make optically transparent paper for electronic displays, to create DNA-hybrid materials, to generate hierarchical composites and for use in foams, aerogels and starch nanocomposites and the use of all-cellulose nanocomposites for enhanced coupling between matrix and fibre. A comprehensive coverage of the literature is given and some suggestions on where the field is likely to advance in the future are discussed.

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Review: current international research into cellulose nanofibres and nanocomposites

Amide bond formation is a fundamentally important reaction in organic synthesis, and is typically mediated by one of a myriad of so-called coupling reagents. This critical review is focussed on the most recently developed coupling reagents with particular attention paid to the pros and cons of the plethora of “acronym” based reagents. It aims to demystify the process allowing the chemist to make a sensible and educated choice when carrying out an amide coupling reaction (179 references).

http://www.chtf.stuba.sk/~szolcsanyi/education/files/Organicka%20chemia%20II/Prednaska%208_Aminokyseliny%20a%20peptidy/Doplnkove%20studijne%20materialy/Amide%20bond%20formation/Amide%20bond%20formation%20-%20beyond%20the%20myth%20of%20coupling%20reagents.pdf

Amide bond formation: beyond the myth of coupling reagents

Many, if not most, redox reactions are coupled to proton transfers. This includes most common sources of chemical potential energy, from the bioenergetic processes that power cells to the fossil fuel combustion that powers cars. These proton-coupled electron transfer or PCET processes may involve multiple electrons and multiple protons, as in the 4 e–, 4 H+ reduction of dioxygen (O2) to water (eq 1), or can involve one electron and one proton such as the formation of tyrosyl radicals from tyrosine residues (TyrOH) in enzymatic catalytic cycles (eq 2). In addition, many multi-electron, multi-proton processes proceed in one-electron and one-proton steps. Organic reactions that proceed in one-electron steps involve radical intermediates, which play critical roles in a wide range of chemical, biological, and industrial processes. This broad and diverse class of PCET reactions are central to a great many chemical and biochemical processes, from biological catalysis and energy transduction, to bulk industrial chemical processes, to new approaches to solar energy conversion. PCET is therefore of broad and increasing interest, as illustrated by this issue and a number of other recent reviews.

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Thermochemistry of Proton-Coupled Electron Transfer Reagents and its Implications

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Carbodiimide chemistry: recent advances

Concertedness in acyl group transfer in solution: a single transition state in acetyl group transfer between phenolate ion nucleophiles

Concerted acetyl-group transfer between substituted phenolate ion nucleophiles: variation of transition-state structure as a function of substituent

Publisher Summary This chapter introduces the concept of effective charge in its application to reactions in solution. A case is not being pressed for the application of charge derived from polar effects as the only quantity, whereby information is obtained about bonding; rather it is recognized that polar substituent effects on rates and equilibria in solution are easily and reliably obtained, and they constitute one of our most powerful mechanistic tools for studies of reactions in solution. The methods for charge measurement—namely, 13C nmr and esr spectroscopy—are only for ground or product states and the data refer to the solvated species; the field awaits comparative work. Knowledge of the development of charge on a substrate atom during catalysis is very important for understanding; its interpretation depends on the charge change in suitable calibration equilibria for the complexation process and also for the process occurring in the complex. These calibrating values are not generally available, but very early studies of the acylation of hydrolytic enzymes by substrates indicated that negative charge development on the leaving group atom is not as pronounced as in simple model reactions in aqueous solvent.

Effective Charge and Transition-state Structure in Solution

Over the past decade, a new awareness of the relationship between conflicts and development has grown. Developmental factors can act as a trigger for violence, as well as for ending violence and for triggering post-conflict reconstruction. This book explores the complexity of the links between violent conflict (usually civil wars) and development, under-development and uneven development. It emphasizes the connections between stable developed economies and civil wars in other parts of the world, and examines how structural factors (such as the organization of the global economy) virtually condemn some regions to conflict and under-development. 
This valuable introductory text explains, reviews and critically evaluates this complex relationship. It focuses on intra-state conflicts and complex political emergencies that combine transnational and internal characteristics. Attention is also given to inter-state conflicts. Chapters emphasize how the relationship between conflict and development traverses many scales (macro, meso and micro) and dimensions (economic, political and cultural). Furthermore it explains how different developmental challenges and opportunities emerge along the full life-cycle of conflict. Specifically, the role of poverty, state, market, civil society, globalization, humanitarian aid, refuges, gender and health within conflict dynamics are examined. The book also investigates specific developmental issues emerging during conflict management and post conflict reconstruction. Both authors have a background in conducting research in deeply divided societies, and argue that many of the processes connected with war and peace making deliberately write people out of the equation. This book attempts to ‘write people in’.
By drawing on contemporary theoretical debates and examining current policies and events, the text unpacks the difficult and complex aspects of the relationships between armed conflict and development and makes them accessible, interesting and policy relevant. It considers how peace making, peace building, and post-war reconstruction are usually more sustainable and successful if politicians, policy makers, entrepreneurs and those working for international NGOs take on board local opinion and capacity. Written in an accessible style, the book considers the main contemporary theories and arguments on conflict, development and the interactions between the two. The text is illuminated throughout with case studies drawn from Africa, the Balkans, Asia and the Middle East.

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Andrew Williams

Papers

Carbodiimide chemistry: recent advances

Concertedness in acyl group transfer in solution: a single transition state in acetyl group transfer between phenolate ion nucleophiles

Concerted acetyl-group transfer between substituted phenolate ion nucleophiles: variation of transition-state structure as a function of substituent

Effective Charge and Transition-state Structure in Solution

Conflict and Development