Congenital dyserythropoietic anaemia, type I, in a Caucasian patient with retinal angioid streaks (homozygous Arg1042Trp mutation in codanin-1).

A congenital dyserythropoietic anaemia (CDA) was recognised in a French Caucasian male patient. Blood smears showed a pronounced aniso-poikilocytosis. Bone marrow light microscopy showed signs of dyserythropoesis, but no internuclear chromatin bridges. Electron microscopy disclosed erythroblast nuclei with the Swiss cheese aspect and the presence of cytoplasmic organelles, assessing the diagnosis of CDA I. The presence of internuclear chromatin bridges may thus be missing in CDA I. The patient proved to be homozygous for the Arg1042Trp mutation in codanin-1 (the 'Bedouin mutation'). By the age of 25, the patient's vision started to deteriorate as a result of retinal angioid streaks and macular abnormalities. Evolution was controlled and the patient, being nearly 50 yr old now, still has a partial use of his eyes. This second case of retinal angioid streaks reported in CDA I adds to the non-haematological features likely to be associated with this condition.

The effect of tamoxifen on the reproductive traits in White Leghorn cockerels.

Fifty White Leghorn male chicks were divided into five equal groups of ten chicks each. Beginning at two weeks of age they were injected on each alternate day as follows: corn oil as a vehicle control or 0.5, 1.0, 5.0, or 10.0 mg tamoxifen/kg/b.wt. The whole experimental period lasted until twelve weeks of age. The two lowest doses of tamoxifen (TAM) enhanced comb growth, while the highest dose suppressed it. The two lowest doses of TAM also caused an earlier increase in sexual activity of the chicks, and precocious production of semen. At nine weeks of age the 0.5 and 1.0 mg doses of TAM increased plasma testosterone to a level three times higher than in the controls. This effect was not observed with the highest dose of TAM. At 12 weeks of age the chicks treated with 1 mg TAM had larger testes than the controls and produced three times more sperm per ejaculation. At this stage chicks treated with the highest dose of tamoxifen produced less sperm than the control and had smaller testes and adenohypophyses.

SIN1 interacts with a protein that binds the URS1 region of the yeast HO gene.

Evidence has recently been mounting suggesting that a number of chromatin components previously thought to primarily or exclusively have structural function, also have a regulatory role in eukaryotic transcription. Notably, in yeast, histone H4 N-terminal sequence has been shown to be required for promoter activation of certain genes in vivo, and mutations in histone H3 (SIN2) or in SIN1 (which has some sequence similarity to HMG1) are able to suppress swi1, swi2, and swi3 mutations, restoring transcription to HO as well as a number of other genes. In this paper we report the identification of a novel protein or protein complex that specifically binds a short sequence in the HO regulatory region on the one hand, and on the other somehow appears to contact the SIN1 protein. We have shown that the DNA binding activity itself does not contain SIN1, since extracts from sin1 delta strains retain the activity. Interestingly, extracts made from cells carrying the dominant sin1-2 point mutation lack the binding activity. Furthermore, bacterially produced sin1-2 protein can dissociate a DNA/protein complex while a similarly produced SIN1 protein has no effect on the complex at similar concentrations. When the DNA sequence to which the protein complex binds is placed in a CYC1 promoter lacking a UAS (upstream activating sequence), it can serve as a weak UAS in a SIN1 dependent way. Our data imply that a sequence specific DNA binding protein(s) may mediate between the SIN1 protein and the basal transcription apparatus transcribing HO.

Resolving pathways of interaction of covalent inhibitors with the active site of acetylcholinesterases: MALDI-TOF/MS analysis of various nerve agent phosphyl adducts.

Understanding reaction pathways of phosphylation, reactivation, and "aging" of AChE with toxic organophosphate compounds is both a biochemical and a pharmacological challenge. Here we describe experiments which allowed to resolve some of the less well understood reaction pathways of phosphylation and "aging" of acetylcholinesterase (AChE) involving phosphoroamidates (P-N agents) such as tabun or the widely used pesticide methamidophos. Tryptic digests of phosphylated AChEs (from human and Torpedo californica), ZipTip peptide fractionation and matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF/MS) enabled reproducible signal enrichment of the isotopically resolved peaks of organophosphoroamidate conjugates of the AChE active site Ser peptides. For tabun and its hexadeuterio analogue, we find, as expected, that the two phosphoramidate adducts of the active site peptide differ by 6.05 mass units but following aging we find that the two corresponding phospho-peptides have identical molecular weights. We further show that the aging product of paraoxon-AChE adduct is identical to the aging product of the tabun-AChE conjugate. These results unequivocally demonstrate that the pathway of aging of tabun adducts of the human or the Torpedo californica AChEs proceeds through P-N bond scission. For methamidophos, we show that phosphylation of AChE involves elimination of the thiomethyl moiety and that the spontaneous reactivation of the resulting organophosphate adduct generates the phosphorus free AChE active site Ser-peptide.

A clinical and molecular study of a Bedouin family with dysmegakaryopoiesis, mild anemia, and neutropenia cured by bone marrow transplantation.

OBJECTIVES: Familial thrombocytopenia is a relatively rare and heterogeneous group of clinical and genetic syndromes of unknown etiology. Recently, mutations in a few hematopoietic transcription factors were implicated in dysmegakaryopoiesis with and without dyserythropoietic anemia. The aim of the present study was to describe the clinical and hematologic picture of members of a Bedouin family with severe congenital thrombocytopenia associated with neutropenia and anemia and to determine the possible involvement of hematopoietic transcription factor genes in their disease. PATIENTS AND METHODS: Four members of a Bedouin family presented with severe bleeding tendency, including intracranial hemorrhage in three. Three of the four were successfully treated with allogenic human leukocyte antigen (HLA)-matched bone marrow transplants. Measurements of serum erythropoietin and thrombopoietin levels, bone marrow electron microscopy, and megakaryocytic colony were grown for each patient in addition to DNA amplification and single-strand conformation polymorphism of each exon of the NF-E2, Fli-1, FOG-1, and Gfi-1b in genes. RESULTS: Bone marrow studies revealed dysmegakaryopoiesis and mild dyserythropoiesis. A low number of bone marrow megakaryocyte colony-forming units was found, as well as a slightly elevated serum thrombopoietin level. No mutation was identified in any of the transcription factor genes examined. CONCLUSIONS: A unique autosomal recessive bone marrow disorder with prominent involvement of megakaryocytes is described. Defects were not identified in transcription factors affecting the common myeloid progenitor.