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An interval on barley (Hordeum vulgare L.) chromosome 7 accounting for significant quantitative trait locus effects for winter hardiness were detected in a winter (Dicktoo) X spring (Morex) barley population (P.M. Hayes, T. Blake, T.H.H. Chen, S. Tragoonrung, F. Chen, A. Pan, and B. Liu [1993] 900-910). To investigate the possible role of D h n l and Dhn2 in winter hardiness, we examined the expression pattern of six barley dehydrin gene family members in shoot tissue in response to cold temperature. lncubation of 3-week-old barley plants at 2°C resulted in a rapid induction of a single 86-kD polypeptide that was recognized by an antiserum against a peptide conserved in the dehydrin gene family. Northern blot analysis confirmed the induction of an mRNA corresponding to Dhn5. The expression patterns of coldinduced dehydrins in shoot tissue for Dicktoo and Morex were identical under the conditions studied, in spite of the known phenotypic differences in their winter hardiness. These results, together with the allelic structure of selected high-and low-survival lines, suggest that the Dicktoo alleles at the Dhnl and Dhn2 may not be the primary determinants of winter hardiness i n barley.Despite recent advances in identifying genes induced during cold acclimation (see review by Thomashow, 1993), little is understood about the molecular basis of cold hardiness. With the long-term goal of elucidating the genetic control of winter hardiness, we mapped QTL associated with winter hardiness in a population of DH lines derived from the cross of a winter (Dicktoo) and spring (Morex) barley (Hordeum vulgare L.) (Hayes et al., 1993). We identified a QTL on the long arm of barley chromosome 7, controlling winter hardiness traits. This region was found to be responsible for 79% of the phenotypic variation in field survival in Bozeman, MT; 39% of the variance for survival at Corvallis, OR; 32% of the variance for LT,,, and 22% of the variance for crown fructan content (Pan et al.,

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Abstract. The signal requirement for the nuclear import of U1 RNA in somatic cells from different species was investigated by microinjection of both digoxygenin-labeled wild type and mutant U1 RNA molecules and in vitro reconstituted U1 snRNPs. U1 RNA was shown to be targeted to the nucleus by a temperature-dependent process that requires the prior assembly of RNPs from the common proteins and the microinjected RNA. Competition in the cell between immunoaftinity-purified U1 snRNPs and digoxygeninlabeled U1 snRNPs reconstituted in vitro showed that the transport is saturable and should therefore be a mediated process. The transport of a karyophilic protein under the same conditions was not affected, indicating the existence of a U snRNP-specific transport pathway in somatic cells, as already seen in the Xenopus/aev/s ooeyte system. Surprisingly, the signal requirement for nuclear transport of U1 snRNP was found to differ between oocytes and somatic cells from mouse, monkey and Xenopus, in that the m3GGpppG-cap is no longer an essential signaling component in somatic cells. However, as shown by investigation of the transport kinetics of m3GpppG-and ApppG-capped U1 snRNPs, the m3GpppG-cap accelerates the rate of U1 snRNP import significantly indicating that it has retained a signaling role for nuclear targeting of U1 snRNP in somatic cells. Moreover, our data strongly suggest that cell specific rather than species specific differences account for the differential m3G-cap requirement in nuclear import of U1 snRNPs. the nuclear envelope, continual exchange of macromolecules between the nucleus and the cytoplasm takes place. For large components, such as proteins, RNAs, and RNA-protein complexes (RNPs), t this transport is signal mediated and saturable and hence a receptormediated process. (Feldherr et al., 1984;Goldfarb et al., 1986;Forbes, 1992). Up to now, the transport of proteins into the nucleus is the best understood of these processes (reviewed in Garcia-Bustos et al., 1991;Silver, 1991). It occurs in two separate steps: the initial binding of the protein to the nuclear pore complex, followed by an ATP-dependent translocation of the protein into the nucleus (Richardson et al., 1988;Newmeyer and Forbes, 1988).The information contained in nuclear location signals (NLS) allows the selective interaction of karyophilic proteins with import receptors (reviewed in Garcia Bustos et al., U. Fischer and J. Heinrich contributed equally to this work.K. van Zee's present address is