Which 3-ribofuranosyl-substituted purine 5′-phosphates undergo template-directed oligomerization?

Summary We have studied the oligomerization reactions of the 2-methylimidazolide derivatives of 3-isoisoguanosine 5-phosphate (2) and 3-isoxanthosine 5-phosphate (5) in the presence of a variety of homopolynucleotide templates. In no case did we observe a substantial template-facilitated production of long oligomers. Polyuridylic acid directed the synthesis of low molecular-weight products from both monomers. Polycytidylic acid, polyadenylic acid, polyinosinic acid, and polyguanylic acid were ineffective as templates in the systems that we investigated.     

A Ca2+/CaM-dependent kinase from pea is stress regulated and in vitro phosphorylates a protein that binds to AtCaM5 promoter.

An immuno-homologue of maize Ca2+/calmodulin (CaM)-dependent protein kinase with a molecular mass of 72 kDa was identified in pea. The pea kinase (PsCCaMK) was upregulated in roots in response to low temperature and increased salinity. Exogenous Ca2+ application increased the kinase level and the response was faster than that obtained following stress application. Low temperature-mediated, but not salinity-mediated stress kinase increase was inhibited by the application of EGTA and W7, a CaM inhibitor. The purification of PsCCaMK using immuno-affinity chromatography resulted in coelution of the kinase with another polypeptide of molecular mass 40 kDa (p40). Western blot revealed the presence of PsCCaMK in nuclear protein extracts and was found to phosphorylate p40 in vitro. Gel mobility shift and South-Western analysis showed that p40 is a DNA-binding protein and it interacted specifically with one of the cis acting elements of the Arabidopsis CaM5 gene (AtCaM5) promoter. The binding of p40 to the specific elements in the AtCaM5 promoter was dependent of its dephosphorylated state. Our results suggest that p40 could be an upstream signal component of the stress responses.     

Specific amino acids in the first fibronectin type III repeat of the neural cell adhesion molecule play a role in its recognition and polysialylation by the polysialyltransferase ST8Sia IV/PST

Polysialic acid is an anti-adhesive protein modification that promotes cell migration and the plasticity of cell interactions. Because so few proteins carry polysialic acid, we hypothesized that polysialylation is a protein-specific event and that a specific polysialyltransferase-substrate interaction is the basis of this specificity. The major substrate for the polysialyltransferases is the neural cell adhesion molecule, NCAM. Previous work demonstrates that the first fibronectin type III repeat of NCAM (FN1) was necessary for the polysialylation of the N-glycans on the adjacent immunoglobulin domain (Ig5) (Close, B. E., Mendiratta, S. S., Geiger, K. M., Broom, L. J., Ho, L. L., and Colley, K. J. (2003) J. Biol. Chem. 278, 30796-30805). This suggested that FN1 may be a recognition site for the polysialyltransferases. In this study, we showed that the second fibronectin type III repeat (FN2) of NCAM cannot replace FN1. Arg substitution of three unique acidic amino acids on the surface of FN1 eliminated polysialylation not only of a minimal Ig5-FN1 substrate but also of full-length NCAM. Ala substitution of these residues eliminated Ig5-FN1 polysialylation but not that of full-length NCAM, suggesting that the two proteins are interacting differently with the enzymes and that multiple residues are involved in the enzyme-NCAM interaction. By using another truncated protein, Ig5-FN1-FN2, we confirmed the importance of enzyme-substrate positioning for optimal recognition and polysialylation. In sum, we have found that acidic residues on the surface of FN1 are part of a larger protein interaction region that is critical for NCAM recognition and polysialylation by the polysialyltransferases.     

Genome wide association studies (GWAS) of spot blotch resistance at the seedling and the adult plant stages in a collection of spring barley

Spot blotch (SB) in barley is caused by the fungal pathogen Cochliobolus sativus and considered one of the major constraints to successful barley production. Resistance to C. sativus was evaluated, using a barley collection of 336 genotypes (AM-2014), at the seedling and adult stages. Seedling resistance was evaluated by using a mixture of 19 virulent isolates in Morocco. Virulent isolates prevalent in Uttar Pradesh were used for phenotyping resistance at the adult stage in India. The AM-2014 panel was genotyped with 9-K single-nucleotide polymorphism (SNP) markers using iSelect Illumina Infinium. Genome wide association studies (GWAS) were carried out using SNP markers, infection responses, disease severity, and area under the disease progress curve (AUDPC). The mixed linear model was employed in TASSEL using principal component analysis (PCA) and Kinship matrix (K) as covariates. Higher SB severity, 82.3?±?13.5 (mean?±?SD), was recorded at the Banaras Hindu University (BHU) compared to 47.6?±?15.0 at the Narendra Dev University of Agriculture and Technology (NDUAT). Nine QTL, Rcs-qtl-1H-126.9, Rcs-qtl-2H-148.16, Rcs-qtl-3H-25.27, Rcs-qtl-5H-80.35, Rcs-qtl-6H-58.24, Rcs-qtl-7H-29.62, Rcs-qtl-7H-29.72, Rcs-qtl-7H-32.81, and Rcs-qtl-7H-34.74, were detected for SB resistance at the seedling stage. For SB severity at the adult stage, a QTL, Rcs-qtl-7H-32.81, was detected at BHU while seven QTL, Rcs-qtl-2H-91.09, Rcs-qtl-3H-145.64, Rcs-qtl-4H-14.43, Rcs-qtl-6H-6.49, Rcs-qtl-7H-114.43, Rcs-qtl-7H-151.66, and Rcs-qtl-7H-150.36, were found for SB severity at NDUAT. Three QTL, Rcs-qtl-4H-18.61, Rcs-qtl-4H-67.91, and Rcs-qtl-5H-110.25, were significant for AUDPC of SB at BHU. The QTLs reported in this study are important to advance marker-assisted selection and gene pyramiding of SB resistance in South Asia and North Africa in future.     

Biological significance of daily variation in immunity of Perdicula asiatica: role of melatonin and testosterone

Daily variation of plasma melatonin affects daily activity pattern of many birds, but daily immunoprotective activity of melatonin in any seasonally breeding avian species is lacking. We report the influence of endogenous melatonin and testosterone on the daily variation in immunity of the Indian tropical bird Perdicula asiatica during reproductively active (RAP) and inactive (RIP) periods when the level of melatonin was high and in the former case. Daily variation in levels of melatonin, testosterone and immune parameters was noted during RAP and RIP. Maximum immune activity was noted at 2:00 hrs during RAP and at 14:00 hrs during RIP. During RAP, high testosterone in the circulation suppressed melatonin levels and immune parameters. A high basal level of melatonin during RIP was responsible for the suppression of testosterone resulting in high immune activity. Therefore, along with testosterone, melatonin acts like a major temporal synchronizer to maintain not only the reproductive rhythm but also daily immune adaptability of this avian species.     

Template-directed oligomerization of 3-isoadenosine 5′-phosphate

Summary Template-directed oligomerization of an activated derivative of 3-isoadenosine 5-phosphate (piA) on polyuridylic acid [poly(U)] was studied. The reaction of ImpiA is more efficient than the corresponding reaction of ImpA, and produces 3–5-linked oligomers while the reaction of ImpA gives only 2–5-linked oligomers. The base pairing between piA and poly(U) in this system is probably of the Hoogsteen type (involving the 6-amino group and N7 of 3-isoadenosine) rather than of the Watson-Crick type.