Life tables of Moina macrocopa (Straus) in successive generations under food and temperature adaptation

Life tables of Moina macrocopa (Straus) cultured at seven foodconcentrations (FC) (Scenedesmus sp., 1.49–1490 mg wet weightl^-1, 10⁴–10⁶ cellml^-1) were investigated for animals of the first generation(nonadapted animals) and for animals of the third generation (adaptedanimals) cultivated at these FC. Adapted animals showed a trophicpreferendum, i.e. a narrow FC-range at which maximal R_ovalues were observed in comparison with nonadapted animals. In adaptedanimals, the maximal R_o was 115.3 individual, observed at 20°C and a FC of 74.5 mg wet weight l^-1.     

DNA or RNA Oligonucleotide 2′-Hydrazides for Chemoselective Click-Type Ligation with Carbonyl Compounds

An efficient method for the synthesis of DNA or RNA oligonucleotide 2′-hydrazides is described. Fully deprotected oligonucleotides containing a hydrazide group at the 2′-position of a uridine residue were obtained by a novel two-step procedure: periodate cleavage of an oligonucleotide with 1,2-diol group followed by conversion of the aldehyde to hydrazide with an extended linker arm using a homobifunctional reagent succinic dihydrazide and NaBH₃CN. The resulting oligonucleotide 2′-hydrazides were efficiently conjugated by a click-type reaction at acidic pH to aliphatic or aromatic aldehydes with or without NaBH₃CN reduction to afford novel 2′-conjugates.     

The roles of p53 and p21 in normal development and hyperthermia‐induced malformations

BACKGROUND : Hyperthermia (HS) is a well‐studied teratogen that induces serious malformations, including neural tube defects. Our previous studies have shown that HS induces apoptosis by activating the mitochondrial apoptotic pathway. Prior to activation of the mitochondrial apoptotic pathway, HS also activates p53 and its target genes. In the present study, we determine whether p53 and/or p21 play a role as teratogen suppressors or inducers of HS‐induced malformations. METHODS : Pregnant mice carrying all three p53 or p21 genotype embryos were exposed to HS on day 8.5. Subsequently, fetuses were collected on day 15.5, and genotyped. In addition to genotype, we also determined the number of resorptions and dead fetuses as well as the number and types of external malformations. RESULTS : In the absence of HS exposure, fetuses exhibiting exencephaly and spina bifida were observed in approximately 11% of p53 ?/? fetuses, whereas no malformations were observed among p21 ?/? fetuses. Exposure to HS resulted in an increase in exencephaly and polydactyly in fetuses of all three p53 genotypes. However, the incidence of these malformations was statistically significantly higher in p53 ?/? compared to p53 +/? and p53 +/+ fetuses. Exencephaly was the only malformation observed in p21 fetuses exposed to HS, with an approximately 2‐fold increase among p21 +/? and a 3‐fold increase among p21 ?/? compared to p21 +/+ fetuses. CONCLUSIONS : Our study confirms that p53 plays a role in normal development and has shown, for the first time that p53 and p21 function to suppress HS‐induced malformations. Birth Defects Res (Part B) 86:40‐47, 2009. © 2009 Wiley‐Liss, Inc.     

1,2-Diol and hydrazide phosphoramidites for solid-phase synthesis and chemoselective ligation of 2'-modified oligonucleotides

The preparation of two novel 2'-O-alkyl phosphoramidites bearing 1,2-diol and hydrazide functions for a chemoselective ligation is described. The former amidite was used to obtain 2'-modified oligodeoxyribonucleotides, which can be later oxidised by NaIO4 to generate 2'-aldehyde oligonucleotides. These were successfully conjugated to acceptor molecules. The latter amidite also showed good coupling yields, but the hydrazide function was demonstrated to be labile under basic deprotection conditions.     

Detection of glycosylase, endonuclease and methyltransferase enzyme activities using immobilized oligonucleotides

A novel rapid assay for detection of DNA glycosylase, restriction endonuclease, and DNA methyltransferase enzyme activities is presented. The assay is based on enzyme-dependent label release (in case of glycosylase and endonuclease), or non-release (in case of methyltransferase) into solution from end-labeled DNA immobilized on solid support (CPG or Tenta Gel S-NH2). The assay has been validated for monitoring activity of repair enzyme uracil-DNA glycosylase, restriction endonucleases SsoII, MvaI and EcoRII and (cytosine-5)-DNA methyltransferase SsoII. Two types of labels have been tested and found compatible with the assay: radioactive (32P) and fluorescent (rhodamine B and fluorescein). The enzyme activity is estimated as a ratio of the label released into solution to the total amount of the label. Use of fluorescent labeling facilitates detection while use of solid phase-immobilized substrates facilitates product separation, improved assay sensitivity, and increases throughput of assay. Proposed technique provides an estimate of enzyme activity but not its specific activity. Thus, the assay will most valuable in the applications where rapid estimation of enzyme activity is necessary.