Partial complementation inAspergillus niger heterocaryon

Zusammenfassung Erzwungene Heterokaryen-Vereinigung zwischen Hypoxanthin und Histidin abhängiger Mutanten vonAspergillus niger, die auf minimalem Nährboden ohne Sporenproduktion wachsen. Das Phänomen wird als teilweise Ergänzung bezeichnet und als Gleichgewichtsstörung der Kerntypen im Heterokaryen oder als Verdünnungseffekt eines Genproduktes zweiter Ordnung im Zytoplasma gedeutet.     

The DNA sequence and analysis of human chromosome 13

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.     

Purification and cloning of amyloid precursor protein beta-secretase from human brain

Proteolytic processing of the amyloid precursor protein (APP) generates amyloid beta (Abeta) peptide, which is thought to be causal for the pathology and subsequent cognitive decline in Alzheimer's disease. Cleavage by beta-secretase at the amino terminus of the Abeta peptide sequence, between residues 671 and 672 of APP, leads to the generation and extracellular release of beta-cleaved soluble APP, and a corresponding cell-associated carboxy-terminal fragment. Cleavage of the C-terminal fragment by gamma-secretase(s) leads to the formation of Abeta. The pathogenic mutation K670M671-->N670L671 at the beta-secretase cleavage site in APP, which was discovered in a Swedish family with familial Alzheimer's disease, leads to increased beta-secretase cleavage of the mutant substrate. Here we describe a membrane-bound enzyme activity that cleaves full-length APP at the beta-secretase cleavage site, and find it to be the predominant beta-cleavage activity in human brain. We have purified this enzyme activity to homogeneity from human brain using a new substrate analogue inhibitor of the enzyme activity, and show that the purified enzyme has all the properties predicted for beta-secretase. Cloning and expression of the enzyme reveals that human brain beta-secretase is a new membrane-bound aspartic proteinase.     

空间n边形中的正弦定理

利用向量代数中的一个基本等式进行推证,得出了在空间 ｎ 边形中正弦定理的表现形式。使文［１］,［２］,［３］更加完整     

Nonsense mutation in the glucokinase gene causes early-onset non-insulin-dependent diabetes mellitus.

Maturity-onset diabetes of the young (MODY) is a form of non-insulin-dependent (type 2) diabetes mellitus (NIDDM) which is characterized by an early age at onset and an autosomal dominant mode of inheritance. Except for these features, the clinical characteristics of patients with MODY are similar to those with the more common late-onset form(s) of NIDDM. Previously we observed tight linkage between DNA polymorphisms in the glucokinase gene on the short arm of chromosome 7 and NIDDM in a cohort of sixteen French families having MODY. Glucokinase is an enzyme that catalyses the formation of glucose-6-phosphate from glucose and may be involved in the regulation of insulin secretion and integration of hepatic intermediary metabolism. Because the glucokinase gene was a candidate for the site of the genetic lesion in these families, we scanned this gene for mutations. Here we report the identification of a nonsense mutation in the gene encoding glucokinase and its linkage with early-onset diabetes in one family. To our knowledge, this result is the first evidence implicating a mutation in a gene involved in glucose metabolism in the pathogenesis of NIDDM.     

Some properties of the goat placental lactogen

Summary Goat placental lactogen was partially purified from a medium collected after placental tissue incubation. The data obtained by disc electrophoresis and isoelectric focusing experiments, as well as by means of radioreceptor assay methods, provide evidence of the similarity between the goat and ovine placental lactogen.The careful technical assistance of L. Tichovská is gratefuly acknowledged.