Gamma-linolenic acid production by Cunninghamella echinulata growing on complex organic nitrogen sources

Growth of two strains of Cunninghamella echinulata on various nitrogen containing raw materials (corn gluten, corn steep, whey concentrate, yeast extract and tomato waste hydrolysate) yielded important amounts of biomass containing various quantities of γ-linolenic acid (GLA) rich cellular lipids. Especially, growth on tomato waste hydrolysate (TWH) yielded 17.6 g/l of biomass containing 39.6% oil and significant quantities of GLA corresponding to 800 mg/l GLA. Mycelium-bounded proteolytic activity was detected during early growth stages on TWH and declined thereafter, increasing the concentration of assimilable nitrogen in the medium. However, addition of glucose in the medium during the stationary phase triggered the biosynthesis of reserve lipid, since an increase of the proportion of neutral lipids from 45% to 79% in total lipids was observed, while polar lipids decreased from 35% to 12% and from 20% to 9% for glycolipids plus sphingolipids and phospholipids, respectively.     

Linkage and mutational analysis of familial Alzheimer disease kindreds for the APP gene region

A large number of familial Alzheimer disease (FAD) kindreds were examined to determine whether mutations in the amyloid precursor protein (APP) gene could be responsible for the disease. Previous studies have identified three mutations at APP codon 717 which are pathogenic for Alzheimer disease (AD). Samples from affected subjects were examined for mutations in exons 16 and 17 of the APP gene. A combination of direct sequencing and single-strand conformational polymorphism analysis was used. Sporadic AD and normal controls were also examined by the same methods. Five sequence variants were identified. One variant at APP codon 693 resulted in a Glu-->Gly change. This is the same codon as the hereditary cerebral hemorrhage with amyloidosis-Dutch type Glu-->Gln mutation. Another single-base change at APP codon 708 did not alter the amino acid encoded at this site. Two point mutations and a 6-bp deletion were identified in the intronic sequences surrounding exon 17. None of the variants could be unambiguously determined to be responsible for FAD. The larger families were also analyzed by testing for linkage of FAD to a highly polymorphic short tandem repeat marker (D21S210) that is tightly linked to APP. Highly negative LOD scores were obtained for the family groups tested, and linkage was formally excluded beyond theta = .10 for the Volga German kindreds, theta = .20 for early-onset non-Volga Germans, and theta = .10 for late-onset families. LOD scores for linkage of FAD to markers centromeric to APP (D21S1/S11, D21S13, and D21S215) were also negative in the three family groups. These studies show that APP mutations account for AD in only a small fraction of FAD kindreds.     

D21S210: A highly polymorphic (GT)n marker closely linked to the β-amyloid protein precursor (APP) gene

We describe a highly polymorphic (GT)n repeat with 14 alleles that is closely linked to the amyloid precursor protein (APP) gene on human chromosome 21. This marker, D21S210, will be useful for studies of linkage of disorders such as Alzheimer disease to the APP gene.     

A Contiguous Physical Map of the Pericentromeric Region of Chromosome 21q between D21Z1 and D21S13E

We constructed a long range restriction map of the pericentromeric 21q region between the centromere, identified by the alphoid DNA sequence D21Z1, and D21S13E. The physical map showed the order and intermarker distances of five new loci, including two for which highly informative dinucleotide repeat polymorphisms were identified. The total distance between D21Z1 and D21S13E was 2400 kb. Comparison of genetic and physical distances indicated that there is about 400 to 500 kb per centimorgan that is not significantly different from the average 470 kb per centimorgan for the whole of chromosome 21q. Our physical mapping results do not indicate suppression of recombination in pericentromeric 21q.     

Identification of growth hormone DNA polymorphisms which respond to divergent selection for abdominal fat content in chickens

Summary Two strains of meat-type chickens which had been derived from the same genetic base, but were selected for high or low abdominal fat content, respectively, were analyzed for polymorphisms in the growth hormone gene (GH). A total of four DNA polymorphisms were identified, one at a SacI restriction site and three at MspI restriction sites. Restriction mapping indicated that all polymorphisms were in exons and/or introns and not in flanking regions of the gene. The incidence of GH polymorphisms was determined in 20 chickens from each strain and significant differences were observed for two of the four polymorphisms. Analysis by DNA fingerprinting using (CAC)₅ as a probe indicated that the inbreeding coefficient was 0.1 in both strains and that random genetic drift was minimal. Thus, the selection for abdominal fat appears to have affected the frequency of alleles of the growth hormone gene. Whether this is the direct consequence of an altered growth hormone gene on fat metabolism or reflects linkage to an allele of a neighbouring gene remains to be determined.     

Cloning of the cDNA for the Human ATP Synthase OSCP Subunit (ATP50) by Exon Trapping and Mapping to Chromosome 21q22.1-q22.2

Exon trapping was used to clone portions of potential genes from human chromosome 21. One trapped sequence showed striking homology with the bovine and rat ATP synthase OSCP (oligomycin sensitivity conferring protein) subunit. We subsequently cloned the full-length human ATP synthase OSCP cDNA (GDB/HGMW approved name ATP50) from infant brain and muscle libraries and determined its nucleotide and deduced amino acid sequence (EMBL/GenBank Accession No. X83218). The encoded polypeptide contains 213 amino acids, with more than 80% identity to bovine and murine ATPase OSCP subunits and over 35% identity to Saccharomyces cerevisiae and sweet potato sequences. The human ATP50 gene is located at 21q22.1-q22.2, just proximal to D21S17, in YACs 860G11 and 838C7 of the Chumakov et al. (Nature 359:380, 1992) YAC contig. The gene is expressed in all human tissues examined, most strongly in muscle and heart. This ATP50 subunit is a key structural component of the stalk of the mitochondrial respiratory chain F₁F₀-ATP synthase and as such may contribute in a gene dosage-dependent manner to the phenotype of Down syndrome (trisomy 21).