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We report a new cytoplasmic male sterility (CMS) source in bread wheat (Triticum aestivum L.) designated as msH1. CMS has been identified during the process of obtaining alloplasmic bread wheat in different Hordeum chilense Roem. Schultz. cytoplasms. It was observed that when using the H. chilense H1 accession, the corresponding alloplasmic line was male sterile. This alloplasmic wheat is stable under different environmental conditions and it does not exhibit developmental or floral abnormalities, showing only slightly reduced height and some delay in heading. On examining microsporogenesis in the alloplasmic line, it was found that different stages of meiosis were completed normally, but abnormal development occurred at the uninucleate-pollen stage at the first mitosis, resulting in failure of anther exertion and pollen abortion. Fertility restoration of the CMS phenotype caused by the H. chilense cytoplasm was associated with the addition of chromosome 6HchS from H. chilense accession H1. Thus, some fertility restoration genes appear to be located in this chromosome arm. Considering the features displayed by the msH1 system, we consider that it has a great potential for the development of viable technology for hybrid wheat production.

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Interspecific and intergeneric hybrids in the Triticeae are valuable for transfers of genes from one species to another and to extend the range of genetic variation available to plant breeders. For a long time, one goal of cereal breeders has been the production of amphiploids between wheat and barley in order to combine desirable features from both species. Since the first success achieved by KRUSE (1973) crossing cultivated barley and wheat (Hordeum vulgure x Triticum aestivum, T. turgidum, and T, monococcum), numerous hybrid combinations between the two genera have been reported (see FEDAK 1992, for a review), mainly involving non-cultivated Hordeum species. Among these, H. chilense is a wild barley from Chile and Argentina with high cross-ability with other Triticeae genera (FEDAK 1992). Crosses between H. chilense and diploid, tetraploid and hexaploid wheats give rise to tetraploid, hexaploid and octoploid tritordeums, respectively (MARTIN and SANCHEZ-MONGE LAGUNA 1982;MARTIN et al. 1987; CABRERA and M A R T~N 1991).Hexaploid tritordeum (2n = 6x = 42, AABBHChHCh) is a subject for a breeding program with the goal of creating a new cereal crop (MART~N 1988) and in this way we intend to incorporate the genetic variability of cultivated barley, H. vulgare, into the gene pool of tritordeum. For achieving this objective hybrids between barley and tritordeum at the three ploidy levels have been produced (MARTIN et al. 1995). Another different approach is to cross barley addition lines in T. aestivum with hexaploid tritordeum. We present here the identification by fluorescence in situ hybridization (FISH) of intergenomic translocations involving barley, wheat and H. chilense chromosomes obtained from crosses between barley addition lines in hexaploid wheat and tritordeum. MATERIALS AND METHODSRoot tips were collected from germinating seeds of advanced lines from the cross between three disomic chromosome addition lines for chromosomes 2H", 3H", and 4H" of barley (Hordeum vulgure) in Triticum aestivum cv. Chinese Spring (CS) (ISLAM et al. 1975) and hexaploid tritordeum (2n = 6x = 42, AABBHchHCh). These root tips were pre-treated for 3 h in a 0.05 YO colchicine solution at 25°C and fixed in 100 % ethanol-acetic acid, 3: 1 (v/v), for at least a week at room temperature. Root tips were then stained in acetocarmine for 3 min, scraped out the meristems and squashed in 45 Y acetic acid on ethanol-cleaned slides. The preparations were frozen in liquid nitrogen, the cover slips subsequently removed and then dehydrated for 3 min each in 70 YO and absolute ethanol at room temperature. The air-dried slides were stored at 4°C until used. Probes used were total genomic H. vulgure DNA and total genomic H. chilense DNA and they were labelled by nick translation with biotin-1 1-dUTP (Roche Corporate, Basel, Switzerland) and digoxigenin-1 1-dUTP (Roche Corporate), respectively. Both probes were mixed to a final concentration of 5 ng/p1 in the hybridization mixture. The in situ hybridization protocol was performed according to CABR...

Although human and mouse antibodies are similar when one considers their diversification strategies, they differ in the extent to which kappa and lambda light chains are present in their respective variable light chain repertoires. While the Igk-V germline genes are preponderant in mice (95% or more), they comprise only 60% in humans. This may account for differences in the structural repertoire encoded in the Igk-V germline genes of these species. However, this subject has not been properly investigated, partially because a systematic structural characterization of the mouse Igk-V germline genes has not been undertaken. In the present study we compiled all available information on mouse Igk-V germline genes to characterize their structural repertoire. As expected, comparison with the structural repertoire of human Igk-V germline genes indicates differences. The most interesting is that the mouse Igk-V germline gene repertoire is more diverse in structural terms than its human counterpart: the mouse encodes seven canonical structure classes (combination of canonical structures in L1 and L3). In contrast, the human encodes only four. Analysis of the evolutionary relationships of human and mouse Igk-V germline genes led us to propose that the difference reflects a strategy of mice to compensate for the small lambda chain contribution to the repertoire of their variable light chains.