Assignment of a gene (NEM1) for autosomal dominant nemaline myopathy to chromosome 1

Nemaline myopathy (NEM) is a neuromuscular disorder characterized by the presence, in skeletal muscle, of nemaline rods composed at least in part of alpha-actinin. A candidate gene and linkage approach was used to localize the gene (NEM1) for an autosomal dominant form (MIM 161800) in one large kindred with 10 living affected family members. Markers on chromosome 19 that were linked to the central core disease gene, a marker at the complement 3 locus, and a marker on chromosome 1 at the alpha-actinin locus exclude these three candidate genes. The family was fully informative for APOA2, which is localized to 1q21-q23. NEM1 was assigned to chromosome 1 by close linkage for APOA2, which is localized to 1q21-q23. NEM1 was assigned to chromosome 1 by close linkage to APOA2, with a lod score of 3.8 at a recombination fraction of 0. Recombinants with NGFB (1p13) and AT3 (1q23-25.1) indicate that NEM1 lies between 1p13 and 1q25.1. In total, 47 loci were investigated on chromosomes 1, 2, 4, 5, 7-11, 14, 16, 17, and 19, with no indications of significant linkage other than to markers on chromosome 1.     

Studies on the oxidation of hemoglobin Zurich (beta 63 E7 Arg)

Autoxidation and chemically-induced oxidation of hemoglobin Zurich (beta 63 E7 Arg) have been investigated by electron paramagnetic resonance and optical absorption spectroscopy. The results show that the replacement of the distal histidine of the hemoglobin beta chains by an arginine greatly enhances the susceptibility of the heme-iron to oxidative challenge. Both the kinetics and the products of the oxidation are pH dependent. Thus, at acidic and neutral pH, treatment of the protein with ferricyanide leads to a fast conversion of the oxy-protein to aquo-methemoglobin, which, eventually, is slowly converted to hemichromes. In contrast, the hydroxy-met derivative, formed upon chemical oxidation at high pH, is rapidly converted to hemichromes. The electron paramagnetic resonance features of the ferric derivatives of hemoglobin Zurich are somewhat singular, reflecting the modifications of the heme environment in the distal region of the abnormal chains. However, they can be related to heme complexes having their structural counterparts in oxidation products of hemoglobin A.     

An improved procedure, involving mass spectrometry, for N-terminal amino acid sequence determination of proteins which are N alpha-blocked.

A modification to a previously described procedure [Gray & del Valle (1970) Biochemistry 9, 2134-2137; Rose, Simona & Offord (1983) Biochem. J. 215, 261-272] for mass-spectral identification of the N-terminal regions of proteins is shown to be useful in cases where the N-terminus is blocked. Three proteins were studied: vesicular-stomatitis-virus N protein, Sendai-virus NP protein, and a rabbit immunoglobulin lambda-light chain. These proteins, found to be blocked at the N-terminus with either the acetyl group or a pyroglutamic acid residue, had all failed to yield to attempted Edman degradation, in one case even after attempted enzymic removal of the pyroglutamic acid residue. The N-terminal regions of all three proteins were sequenced by using the new procedure.     

Evidence for the Presence of Nontranslated T7 Late mRNA in Infected F′(PIF+) Episome-Containing Cells

The inability of T7 to develop in cells of Escherichia coli containing F(+) or substituted F' episomes is a result of the failure to synthesize late proteins; no in vivo translation of mRNA species synthesized by the T7 RNA polymerase occurs. Further experiments have been performed to measure the amount of late mRNA in T7-infected F'(PIF(+)) cells. (We have designated the property of phage inhibition of F factors as PIF; the wild-type episome is therefore F'[PIF(+)].) T7 late proteins were synthesized in vitro by using a system programed with RNA extracted from T7-infected F(-) and F'(PIF(+)) cells. The T7 lysozyme, product of gene 3.5, and the gene 10 head protein were assayed. The following results were obtained: (i) mRNA capable of supporting in vitro synthesis of lysozyme and the gene 10 head protein is present in T7-infected F'(PIF(+)) cells; (ii) lysozyme mRNA extracted from T7-infected F'(PIF(+)) cells is present at 70 to 75% of the level found in T7-infected F(-) cells; (iii) gene 10 mRNA is present at 35 to 78% of the level found in T7-infected F(-) cells. No in vivo synthesis of either lysozyme or gene 10 protein can be detected in T7-infected F'(PIF(+)) cells although normal synthesis of these proteins occurs in F(-) cells. These findings confirm that the block in T7 development in F'(PIF(+)) cells results from the failure to translate late classes of T7 RNA.