The particulate half-cystine-rich copper protein of newborn liver. Relationship to metallothionein and subcellular localization in non-mitochondrial particles possibly representing heavy lysosomes

The particulate half-cystine-rich copper protein of newborn liver can be partially purified by centrifugation of the heavy mitochondrial fraction through glycogen-sucrose or sucrose density gradients. The resulting sediments contained about 4% copper, about 20% half-cystine and a 2 to 3-fold increase in β-glucuronidase specific activity. The copper protein is not a true mitochondrial constituent and the data are consistent with its localization in a distinct population of heavy lysosomes. The amino acid composition of the polypeptide isolated from the crude insoluble copper protein is strikingly similar to that of metallothionein, suggesting that the neonatal protein represents a copper-rich form of metallothionein.     

Effects of incubation temperature and bicarbonate on maturation of pig oocytes in vitro

Pig oocytes cultured at 39 degrees C had a higher percentage of polar body formation than did those cultured at 37 degrees C. A culture medium based on Medium 199 with Earle's salts and supplemented with 15% serum from a young castrated boar was just as good as the same formulation containing additional pyruvate, lactate and insulin, and superior to a modified Krebs-Ringer bicarbonate medium. When the bicarbonate buffer system (Earle's salts) of Medium 199 was replaced with a phosphate buffer system (Hank's salts), the rate of polar body formation was decreased. When the Hank's based medium was supplemented with a bicarbonate buffer system, polar body formation was restored to the level in Earle's based medium. This suggests that CO2/bicarbonate may be important for the normal maturation of pig oocytes.     

Orangutan α-satellite monomers are closely related to the human consensus sequence

Alpha-satellite is a family of tandemly repeated DNA found at the centromeric regions of all human and primate chromosomes. Human α-satellite subsets are largely chromosome-specific and have been further grouped into four suprachromosomal families (SFs), each characterized by a unique set of monomeric types. Although chimpanzee and gorilla α-satellites share sufficient sequence similarity to fit the established SFs, the assumption that the derived human α-satellite consensus and monomeric types represent the sequence of ancestral repeats remains unestablished. By using oligonucleotide primers specific for a conserved region of human α-satellite DNA, we have PCR amplified, cloned, and characterized α-satellite sequences from the orangutan genome. Nucleotide sequence analysis demonstrated that orangutan α-satellite is formed by a single monomeric type that is significantly closer in percentage of sequence identity (mean = 92%, range = 89–96%) to the overall consensus of human α-satellite than to the monomeric types corresponding to the four SFs. Use of cloned sequences as hybridization probes to orangutan genomic DNA digested with a panel of restriction enzymes showed that most orangutan α-satellite subsets are characterized by a monomeric construction. The subset homologous to clone PPY2-5 is organized in distinct higher-order repeat structures consisting of 18 adjacent monomers. By FISH two clones, PPY3-4 and PPY3-5, proved to be specific for the α-satellite on the orangutan homologs of human Chromosomes (Chrs) 10 and 8, respectively. Our data indicate that there was an ancestral monomeric type displaying high sequence similarity to the overall human consensus from which the different great ape and human subsets and SFs may have originated. Received: 24 November 1997 / Accepted: 29 January 1998