A consensus linkage map of barley

A consensus linkage map of the barley genome was constructed. The map is based on six doubled haploid and one F₂ population. The mapping data for three of the doubled haploid populations was obtained via the GrainGenes database. To allow merger of the maps, only RFLP markers that produce a single scorable band were included. Although this reduced the available markers by about half, the resultant map contains a total of 587 markers including 87 of known function. As expected, gene order was highly conserved between maps and all but two discrepancies were found in closely linked markers and are likely to result from the small population sizes used for some maps. The consensus map allows the rapid localisation of markers between published maps and should facilitate the selection of markers for high-density mapping in defined regions.     

Germ-Line Mutations in the von Hippel–Lindau Tumor-Suppressor Gene Are Similar to Somatic von Hippel–Lindau Aberrations in Sporadic Renal Cell Carcinoma

von Hippel–Lindau (VHL) disease is a hereditary tumor syndrome predisposing to multifocal bilateral renal cell carcinomas (RCCs), pheochromocytomas, and pancreatic tumors, as well as angiomas and hemangioblastomas of the CNS. A candidate gene for VHL was recently identified, which led to the isolation of a partial cDNA clone with extended open reading frame, without significant homology to known genes or obvious functional motifs, except for an acidic pentamer repeat domain. To further characterize the functional domains of the VHL gene and assess its involvement in hereditary and nonhereditary tumors, we performed mutation analyses and studied its expression in normal and tumor tissue. We identified germ-line mutations in 39% of VHL disease families. Moreover, 33% of sporadic RCCs and all (6/6) sporadic RCC cell lines analyzed showed mutations within the VHL gene. Both germ-line and somatic mutations included deletions, insertions, splice-site mutations, and missense and nonsense mutations, all of which clustered at the 3' end of the corresponding partial VHL cDNA open reading frame, including an alternatively spliced exon 123 nt in length, suggesting functionally important domains encoded by the VHL gene in this region. Over 180 sporadic tumors of other types have shown no detectable base changes within the presumed coding sequence of the VHL gene to date. We conclude that the gene causing VHL has an important and specific role in the etiology of sporadic RCCs, acts as a recessive tumor-suppressor gene, and appears to encode important functional domains within the 3' end of the known open reading frame.     

The Tc5 Family of Transposable Elements in Caenorhabditis Elegans

We have identified Tc5, a new family of transposable genetic elements in the nematode Caenorhabditis elegans. All wild-type varieties of C. elegans that we examined contain 4-6 copies of Tc5 per haploid genome, but we did not observe transposition or excision of Tc5 in these strains. Tc5 is active, however, in the mut-2 mutant strain TR679. Of 60 spontaneous unc-22 mutations isolated from strain TR679, three were caused by insertion of Tc5. All three Tc5-induced mutations are unstable; revertants result from precise or nearly precise excision of Tc5. Individual Tc5 elements are similar to each other in size and structure. The 3.2-kb element is bounded by inverted terminal repeats of nearly 500 bp. Eight of the ten terminal nucleotides of Tc5 are identical to the corresponding nucleotides of Tc4. Further, both elements recognize the same target site for insertion (CTNAG) and both cause duplication of the central TNA trinucleotide upon insertion. Other than these similarities to Tc4, Tc5 is unrelated to the three other transposon families (Tc1, Tc3 and Tc4) that transpose and excise at high frequency in mut-2 mutant strains. Mechanisms are discussed by which four apparently unrelated transposon families are all affected by the same mut-2 mutation.     

Characterization of a psychrotrophic Clostridium causing spoilage in vacuum-packed cooked pork: description of Clostridium algidicarnis sp. nov.

A Clostridium species causing spoilage of vacuum-packed refrigerated pork was isolated and characterized. The unknown organism differed phenotypically from other clostridial species usually associated with spoilage. Phylogenetic analyses based on 16S rRNA gene sequencing demonstrated that the psychrotroph represents a distinct line of descent within the genus Clostridium. It is proposed that the organism be classified as a new species of the genus Clostridium, Clostridium algidicarnis .     

Germline and somatic mosaicism in a female carrier of Duchenne muscular dystrophy

The family of a male with Duchenne muscular dystrophy (DMD) and a deletion within the dystrophin gene has been studied. Polymerase chain reaction analysis of ectopic mRNA from peripheral blood T+B lymphocytes and the use of (CA) _n repeat polymorphisms in and around the deleted region showed the proband's mother to be both a germline mosaic and a somatic mosaic for the deletion seen in her son. The mutation therefore occurred as a mitotic event early in embryogenesis.     

Genetic mapping of 14 short tandem repeat polymorphisms on human chromosome 22

We have constructed a linkage map of 14 short tandem repeat polymorphisms (11 with heterozygosity > 70%) on the long arm of human chromosome 22 using 23 non-CEPH pedigrees. Twelve of the markers could be positioned uniquely with a likelihood of at least 1,000:1, and distributed at an average distance of 6.62 cM (range 1.5–16.1 cM). The sex-combined map covers a total of 79.6 cM, the female map 93.2 cM and the male map 64.6 cM. Based on comparisons between physical maps and other genetic maps, we estimate that our map covers 70%–80% of the chromosome. The map integrates markers from previous genetic maps and uniquely positions one marker (D22S307). Data from physical mapping on the location of four genetic markers correlates well with our linkage map, and provides information on an additional marker (D22S315). This map will facilitate high resolution mapping of additional polymorphic loci and disease genes on chromosome 22, and act as a reference for building and verifying physical maps.     

Myosin light chain kinase expression during smooth muscle development

The expression of smooth muscle myosin light chain kinase (MLCK) was investigated during chicken gizzard development. The molecular weight and the antigenic properties of MLCK did not change during development. The use of anion exchange high performance liquid chromatography (HPLC) enabled us to distinguish between MLCKs from post-hatched and adult chickens. A partial amino acid sequence determination of 4-day-old gizzard MLCK failed to disclose differences in the primary sequences of the two proteins. The results suggest that MLCK has the same primary sequence in all sequences of the two proteins. The results suggest that MLCK has the same primary sequence in all stages of gizzard development, although charge variants due to post-translational modifications may exist.     

Development of IVM-IVF produced 8-cell bovine embryos in simple,serum-free media after conditioning or Co-culture with buffalo rat liver cells

Development of 8-cell bovine embryos derived from in vitro matured/in vitro fertilized (IVM/IVF) oocytes was evaluated in two simple, serum-free media (CZB and SOM) with buffalo rat liver cells co-culture (BRLC) or after conditioning compared to a commonly used, serum-supplemented complex medium TCM-199. In a 3 x 4 factorial design, 578 eight-cell embryos were randomly assigned to 12 treatment groups. The factors were: first, type of culture medium (M199/FBS, CZBg and SOM), and second, the use of BRLC (as co-culture or to condition media for 24 hr and 48 hr) and unconditioned media. Development to morula was not affected by the type of medium, but co-culture and 48 hr conditioning within media type resulted in better development when compared to the 24-hr conditioned or unconditioned groups. Blastocyst development in SOM (38.9%) was different (P < 0.05) than in CZBg (46.6%) and M199/FBS (48.7%) and was lowest in the unconditioned group (27.8%) followed by 24 hr conditioned (33.3%), 48 hr (56.3%), and co-culture (59.6%). No blastocyst expansion was observed with unconditioned media and 24 hr conditioned SOM. Significant differences (P < 0.05) were found among all treatment groups except the co-culture and 48-hr conditioned groups. Hatching occurred only with co-culture and 48-hr conditioned groups of M199/FBS and CZBg media. These data show that CZB with glucose conditioned by BRLC monolayers for 48 hr can support the development of IVM/IVF produced bovine embryos to blastocyst compared to culture in TCM-199 with serum. © 1994 Wiley-Liss, Inc.     

Kin recognition and cannibalism in polyphenic salamanders

We investigated kin discrimination among larvae of Arizona tigersalamanders (Ambystoma tigrinum nebulosum) which occur as "typical"morphs that feed mostly on invertebrate prey and occasionallyon conspecifics, and as "cannibal" morphs that feed primarilyon conspecifics. When housed with smaller larvae that differedin relatedness, both cannibals and typicals preferentially consumedless-related individuals. Cannibals ate typicals much quickerwhen the choice was between nonkin and siblings than when thechoice was between nonkin and cousins, indicating that cannibalscould distinguish different categories of relatives. Cannibalswere less likely to eat a larval sibling that was a cannibalmorph than a sibling that was a typical morph. Occluding animals'nares temporarily eliminated kin discrimination, implying thatolfaction is important in recognition. Larvae from differentsibships varied considerably in their ability to discriminatekin, and the greater the probability that a larva from a givensibship would develop into a cannibal morph, the more likelythe members of that sibship were to discriminate kin. Our resultsenable us to infer the functional significance of kin recognitionin this species and to develop an evolutionary model of themechanisms underlying the joint control of kin recognition andcannibalistic polyphenism.