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The effect of thrombin stimulation on actin organization in human platelets has been analyzed by using the DNase I inhibition assay, which is selective for unpolymerized and filamentous actin. Te results provide biochemical evidence for the suggestion that stimulation leads to rapid polymerization of actin. The measurements also reveal changes in the polymerization state of actin occurring after cell lysis. These changes are influenced by the concentration of free calcium in the extracts.

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Messenger ribonucleic acid (mRNA) from cells productively infected with adenovirus type 2 was isolated by affinity chromatography on polyuridylic acid [poly (U)] bound to Sepharose. At least 90% of the polyadenylic acid [poly (A)]-containing polysomal mRNA was retained by the poly (U) Sepharose and thus separated from more than 95% of the ribosomal RNA and transfer RNA. In these experiments, 65% of the early (3 to 5 hr postinfection) and 85% of the late (14 to 16 hr postinfection) virus-specific RNA was retained by the poly (U) Sepharose. Early in the infection 18%, and late in the infection more than 95%, of the poly (A)containing fraction, eluted from the poly (U) Sepharose with 90% formamide, was adenovirus-specific, as shown by exhaustive hybridization. Different patterns, containing several distinct species of viral niRNA, were detected early and late in the infectious cycle. No distinct viral mRNA lacking poly (A) was discovered.

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Messenger RNA from polysomes of KB-cells was isolated by affinity chromatography on columns of polyuridylic acid covalently linked to Sepharose. The mRNA molecules were retained by the resin apparently via their poly(A) segments by base pairing to the poly(U). Ribosomal RNA and transfer RNA were not retained by the columns and were thus removed from the mRNA. The mRNA was recovered to an extent of goo/, and apparently in intact form.This method allows studies of mRNA resulting from unabated synthesis and was used here in studies of the size distribution of different classes of oytoplasmic poly(A)-containing RNA. The presence of poly(A)-containing RNA in the non-polysomal fractions of the cytoplasm was demonstrated. This putative mRNA was shown to constitute about 3001, of the total cytoplasmic poly(A)-containing RNA. Also by using the poly(U)-Sepharose technique it was demonstrated that actinomycin D a t low concentration, 0.04 p.g/ml, supresses the appearance of mRNA on polysomes to an extent of 50°/,. This low concentration of the drug was previously though to effect only ribosomal RNA synthesis.Almost all mRNA molecules in mammalian cells contain a covalent.ly linked segment of approximately I80 nucleotides of adenylic acid a t the 3' terminus [l-51. At present the only messengers known to lack poly(A) are those coding for histones [6]. The biological function of the poly (A) is not yet clarified, but it appears to be added immediately after transcription and to be necessary for proper processing and transport of mRNA from nucleus to cytoplasm [7].The present study gives conditions for the quantitative isolation of the poly(A)-containing RNA by affinity chromatography on poly(U) bound to Sepharose. The procedure is based on the finding that poly(A), even when present in high-molecularweight RNA, exhibits a high affinity for poly(U) bound to an insoluble matrix [8,9]. The method enables the rapid isolation of the poly(A)-containing RNA from polysomes as well as from other cytoplasmic fractions and the isolated RNA appears to be obtained in intact form.Recently Aviv and Leder [lo] and Nakazoto and Edmonds [ 111 reported that oligothymidylic acidcellulose and polythymidylic acid-cellulose, respecAbbreviations. Poly(U), polyuridylic acid; poly(A), polyadenylic acid.Enzymes. RNase A or ribonucleate pyrimidine-nucleotido-2'-transferase; RNase T1 or ribonucleate guanine nucleotide-2'-transferase. tively, could be similarly used for the purification of mammalian mRNAs.I n an earlier report [I21 we presented evidence indicating that mRNA associated with polysomes from KB-cells had unexpectedly large molecular weights. The present report gives a more detailed analysis, by sucrose density gradient centrifugation in 99O/, dimethylsulfoxide, of mRNA from polysomes and post-polysomal fractions which had been previously purified on poly(U)-Sepharose. MATERIALS AND METHODSKB-cells were grown in spinner cultures as described previously [12]

Highlights• Scots pine transfer effect models for growth and survival, valid in both Sweden and Finland have been developed. • The models use high-resolution gridded climate data and can predict performance in future climatic conditions. • The models perform well both for unimproved and genetically improved material and can be used to develop deployment recommendations of contemporary forest regeneration material in Sweden and Finland. AbstractIn this study, we developed models of transfer effects for growth and survival of Scots pine (Pinus sylvestris L.) in Sweden and Finland using a general linear mixed-model approach. For model development, we used 378 provenance and progeny trials with a total of 276 unimproved genetic entries (provenances and stand seed check-lots) distributed over a wide variety of climatic conditions in both countries. In addition, we used 119 progeny trials with 3921 selected genetic entries (open-and control pollinated plus-tree families) for testing model performance. As explanatory variables, both climatic indices derived from high-resolution gridded climate datasets and geographical variables were used. For transfer, latitude (photoperiod) and, for describing the site, temperature sum were found to be main drivers for both survival and growth. In addition, interaction terms (between transfer in latitude and site altitude for survival, and transfer in latitude and temperature sum for growth) entail changed reaction patterns of the models depending on climatic conditions of the growing site. The new models behave in a way that corresponds well to previous studies and recommendations for both countries. The model performance was tested using selected plus-trees from open and control pollinated progeny tests. Results imply that the models are valid for both countries and perform well also for genetically improved material. These models are the first step in developing common deployment recommendations for genetically improved forest regeneration material in both Sweden and Finland.

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