The translations of native messenger RNA for rabbit globin and that of poly(A)-free globin messenger RNA have been compared after injection into XenopUs oocytes. The initial rate of translation of poly-(A)-free miINA is close to that found with intact mRNA.However, at longer incubation periods, the rate of globin synthesis with poly(A)-free mRNA is considerably lower than with native mRNA. Similar differences in the template activity of the two mRNA preparations were found with a cell-free extract of Krebs II ascites tumor. It is concluded that the presence of the 3' poly(A)-rich sequence in mRNA is required to ensure high functional stability.

The present study describes a novel heat-stable, water-stress-related protein with a molecular mass of 47 kDa (designated Desc47) in the entomopathogenic nematode Steinernemafeltiae (IS-6). The protein was accumulated about 10-fold (from 7.84 +/- 1.85 to 74.09 +/- 4.35 % relative content level [RCL]) in dehydrated clumps of infective juveniles (IJs), which had lost 344.% of their initial water content (from 65.1 +/- 1.7% to 427 +/- 0.72%) in a desiccation-tolerance-inducing treatment (97% relative humidity [RH] for 3 days). The appearance of Desc47 was accompanied by trehalose accumulation (from 300 to 600 mg trehalose/g protein) during the process of inducing the IJs into a quiescent anhydrobiotic state. A second cycle of IJ dehydration did not alter the RCL of Desc47 (79.3% for the first cycle and 73.3% for the second cycle). Desc47 retained its high RCL (69.7%) in rehydrated active IJs for 3 days, reaching 51.2% of its initial RCL only after a week. No homology to other known proteins was found by mass-spectrometry electrospray-ion-trap analysis. However, of the 5 sequences obtained from the 11protein(ranging from to 21 amino acids), the 21-amino-acid peptide N V A S D A V E T V G N A A G Q A G (D/T) A V showed excellent homology (74% identity in 19 amino acids) to the cold-responsive protein COR14b (g6564861) from Triticum aestivum. In the Caenorhabditis elegans predicted proteome database search, the N21 yielded the first-best identity score (59 % identity in 17 amino acids) to the CE-LEA homologue protein (g2353333). In plants, COR and LEA are related proteins, heat-stable, which are expressed in response to both dehydration and cold acclimation. The implication of the involvement of Desc47 and the osmoprotectant trehalose in the desiccation-tolerance mechanisms of S. feltiae is discussed.

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Reverse transcriptase (RT)-polymerase chain reaction (PCR) and immunocapture (IC)-RT-PCR protocols were developed and optimized for the sensitive detection of Onion yellow dwarf virus, Leek yellow stripe virus and allexiviruses infecting Allium species. Polyvalence of the designed primers was successfully demonstrated, using samples of dierent plant species and geographic origins. Dierent sample preparation procedures were evaluated for their suitability to provide appropriate PCR templates. IC-PCR, RT-PCR with plant tissue extracts, and RT-PCR with total RNA, proved to be 10 2 ±10 4 times more sensitive than double-antibody sandwich-enzymelinked immunosorbent assay (ELISA). Furthermore, à one step' IC-RT-PCR assay was developed using plant leaf extract as template source, which proved to be 102 times more sensitive than ELISA, and convenient for testing large numbers of leaf samples.

The gene action of 2 sugarcane mosaic virus (SCMV) resistance loci in maize, Scmv1 and Scmv2, was evaluated for potyvirus resistance in an isogenic background. All 4 homozygous and 5 heterozygous isogenic genotypes were produced for introgressions of the resistant donor (FAP1360A) alleles at both loci into the susceptible parent (F7) genetic background using simple sequence repeat markers. For SCMV and maize dwarf mosaic virus (MDMV), virus symptoms appeared rapidly in the 3 homozygous genotypes, with susceptibility alleles fixed at 1 or both loci. Although the 9 isogenic genotypes revealed a high level of resistance to Zea mosaic virus (ZeMV), the same 3 homozygous genotypes were only partially resistant. This indicates that 1 resistance gene alone is not sufficient for complete resistance against SCMV, MDMV, and ZeMV. Scmv1 showed strong early and complete dominant gene action to SCMV, but it gradually became partially dominant. Scmv2 was not detected at the beginning, showing dominant gene action initially and additive gene action at later stages. Both genes interacted epistatically (for a high level of resistance, at least 1 resistance allele at each of both loci is required). This implies that double heterozygotes at the 2 loci are promising for producing SCMVresistant hybrids. Results are discussed with respect to prospects for isolation of SCMV and MDMV resistance genes.