Effects of multiple stressors on cyanobacteria abundance vary with lake type

Blooms of cyanobacteria are a current threat to global water security that is expected to increase in the future because of increasing nutrient enrichment, increasing temperature and extreme precipitation in combination with prolonged drought. However, the responses to multiple stressors, such as those above, are often complex and there is contradictory evidence as to how they may interact. Here we used broad scale data from 494 lakes in central and northern Europe, to assess how cyanobacteria respond to nutrients (phosphorus), temperature and water retention time in different types of lakes. Eight lake types were examined based on factorial combinations of major factors that determine phytoplankton composition and sensitivity to nutrients: alkalinity (low and medium‐high), colour (clear and humic) and mixing intensity (polymictic and stratified). In line with expectations, cyanobacteria increased with temperature and retention time in five of the eight lake types. Temperature effects were greatest in lake types situated at higher latitudes, suggesting that lakes currently not at risk could be affected by warming in the future. However, the sensitivity of cyanobacteria to temperature, retention time and phosphorus varied among lake types highlighting the complex responses of lakes to multiple stressors. For example, in polymictic, medium‐high alkalinity, humic lakes cyanobacteria biovolume was positively explained by retention time and a synergy between TP and temperature while in polymictic, medium‐high alkalinity, clear lakes only retention time was identified as an explanatory variable. These results show that, although climate change will need to be accounted for when managing the risk of cyanobacteria in lakes, a ‘one‐size fits‐all’ approach is not appropriate. When forecasting the response of cyanobacteria to future environmental change, including changes caused by climate and local management, it will be important to take this differential sensitivity of lakes into account

Redirection of the transcription factor SP1 to AT rich binding sites by a synthetic adaptor molecule

The ubiquitous transcription factor SP1 binds to a GC rich consensus sequence. Here we describe an adaptor molecule that mediates binding of SP1 to a non-cognate DNA site rich in AT. The adaptor is comprised of a Dervan-type hairpin polyamide with high affinity to an AT rich hexamer duplex. It also carries a 27mer DNA that contains the SP1 consensus sequence. The synthesis and purification of the polyamide-DNA conjugate is reported. Pulldown experiments and western blot analysis demonstrate adaptor mediated binding of SP1 to the hexamer duplex TTGTTA

On facts and artefacts: The difficulty to evaluate an artificial nuclease

A no. of promising synthetic catalysts for the hydrolytic degrdn. of RNA have been developed in recent years. Some of them show remarkable selectivity for pyrimidine nucleotides. The general problem of all these studies is to distinguish between real effects and artifacts caused by traces of contaminating natural RNases. We show that methods representing the current state of the art (diethylpyrocarbonate treatment, sterilization, ultrafiltration, etc.) do not sufficiently protect against severe artifacts. However, an incorruptible assay could be found by comparing the cleavage of RNA and its mirror image. Enantiomeric RNA is completely resistant to enzymic degrdn., whereas achiral nonpeptide catalysts, by fundamental laws of symmetry, cannot distinguish between enantiomers and will induce exactly the same cleavage pattern with both substrates. [on SciFinder (R)

Site-specific cleavage of RNAs derived from the PIM1 3′-UTR by a metal-free artificial ribonuclease

Oligonucleotide conjugates of tris(2-aminobenzimidazole) have been reported previously to cleave complementary RNA strands with high levels of sequence and site specificity. The RNA substrates used in these studies were oligonucleotides not longer than 29-mers. Here we show that ~150–400-mer model transcripts derived from the 3′-untranslated region of the PIM1 mRNA reacted with rates and specificities comparable to those of short oligonucleotide substrates. The replacement of DNA by DNA/LNA mixmers further increased the cleavage rate. Tris(2-aminobenzimidazoles) were designed to interact with phosphates and phosphate esters. A cell, however, contains large amounts of phosphorylated species that may cause competitive inhibition of RNA cleavage. It is thus important to note that no loss in reaction rates was observed in phosphate buffer. This opens the way to in-cell applications for this type of artificial nuclease. Furthermore, we disclose a new synthetic method giving access to tris(2-aminobenzimidazoles) in multigram amounts

Site-Specific Cleavage of RNAs Derived from the <i>PIM1</i> 3′-UTR by a Metal-Free Artificial Ribonuclease

Oligonucleotide conjugates of tris(2-aminobenzimidazole) have been reported previously to cleave complementary RNA strands with high levels of sequence and site specificity. The RNA substrates used in these studies were oligonucleotides not longer than 29-mers. Here we show that ~150&#8315;400-mer model transcripts derived from the 3&#8242;-untranslated region of the PIM1 mRNA reacted with rates and specificities comparable to those of short oligonucleotide substrates. The replacement of DNA by DNA/LNA mixmers further increased the cleavage rate. Tris(2-aminobenzimidazoles) were designed to interact with phosphates and phosphate esters. A cell, however, contains large amounts of phosphorylated species that may cause competitive inhibition of RNA cleavage. It is thus important to note that no loss in reaction rates was observed in phosphate buffer. This opens the way to in-cell applications for this type of artificial nuclease. Furthermore, we disclose a new synthetic method giving access to tris(2-aminobenzimidazoles) in multigram amounts

Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA

TEMPO spin labels protected with 2-nitrobenzyloxymethyl groups were attached to the amino residues of three different nucleosides: deoxycytidine, deoxyadenosine, and adenosine. The corresponding phosphoramidites could be incorporated by unmodified standard procedures into four different self-complementary DNA and two RNA oligonucleotides. After photochemical removal of the protective group, elimination of formic aldehyde and spontaneous air oxidation, the nitroxide radicals were regenerated in high yield. The resulting spin-labeled palindromic duplexes could be directly investigated by PELDOR spectroscopy without further purification steps. Spin–spin distances measured by PELDOR correspond well to the values obtained from molecular models

Redirection of miRNA‐argonaute complexes to specific target sites by synthetic adaptor molecules

Dysregulation of miRNAs is connected with a multitude of diseases for which antagomirs and miRNA replacement are discussed as therapeutic options. Here, we suggest an alternative concept based on the redirection of RISCs to non‐native target sites. Metabolically stable DNA‐LNA mixmers are used to mediate the binding of RISCs to mRNAs without any direct base complementarity to the presented guide RNA strand. Physical redirection of a dye‐labeled miRNA model and of specific miRNA‐programmed RISC fractions present in HeLa extracts is demonstrated by pull‐down experiments with biotinylated capture oligonucleotides

Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA

TEMPO spin labels protected with 2-nitrobenzyloxymethyl groups were attached to the amino residues of three different nucleosides: deoxycytidine, deoxyadenosine, and adenosine. The corresponding phosphoramidites could be incorporated by unmodified standard procedures into four different self-complementary DNA and two RNA oligonucleotides. After photochemical removal of the protective group, elimination of formic aldehyde and spontaneous air oxidation, the nitroxide radicals were regenerated in high yield. The resulting spin-labeled palindromic duplexes could be directly investigated by PELDOR spectroscopy without further purification steps. Spin–spin distances measured by PELDOR correspond well to the values obtained from molecular models

Astronomy and astrophysics abstracts: literature 1972, part 1

Astronomy and Astrophysics Abstracts, which has appeared in semi-annual volumes since 1969, is de­ voted to the recording, summarizing and indexing of astronomical publications throughout the world. It is prepared under the auspices of the International Astronomical Union (according to a resolution adopted at the 14th General Assembly in 1970). Astronomy and Astrophysics Abstracts aims to present a comprehensive documentation of Iiterature in all fields of astronomy and astrophysics. Every effort will be made to ensure that the average time interval between the date of receipt of the original Iiterature and publication of the abstracts will not exceed eight months. This time interval is near to that achieved by monthly abstracting journals, com­ pared to which our system of accumulating abstracts for about six months offers the advantage of greater convenience for the user. Valurne 7 contains Iiterature published in 1972 and received before August 15, 1972; some older Iiter­ ature which was received late and which is not recorded in earlier volumes is also included

Astronomy and astrophysics abstracts: literature 1973, part 1

Astronomy and Astrophysics Abstracts, which has appeared in semi-annual volumes since 1969, is de­ voted to the recording, summarizing and indexing of astronomical publications throughout the world. It is prepared under the auspices of the International Astronomical Union (according to a resolution adopted at the 14th General Assembly in 1970). Astronomy and Astrophysics Abstracts aims to present a comprehensive documentation of literature in all fields of astronomy and astrophysics. Every effort will be made to ensure that the average time interval between the date of receipt of the original literature and publication of the abstracts will not exceed eight months. This time interval is near to that achieved by monthly abstracting journals, com­ pared to which our system of accumulating abstracts for about six months offers the advantage of greater convenience for the user. Volume 9 contains literature published in 1973 and received before August 15, 1973; some older liter­ ature which was received late and which is not recorded in earlier volumes is also included. We acknowledge with thanks contributions to this volume by Dr. J. Bouska, who surveyed journals and publications in the Czech language and supplied us with abstracts in English, and by the Common­ wealth Scientific and Industrial Research Organization (C.S.I.R.O.), Sydney, for providing titles and abstracts of papers on radio astronomy