Identification of a candidate missense mutation in a family with von Willebrand disease type IIC

A screening project to identify candidate molecular defects causing von Willebrand disease type IIC (VWD IIC) in a German family was carried out using polymerase chain reaction (PCR) amplification of all 52 exons of the von Willebrand factor (VWF) gene, subsequent electrophoresis of single and double stranded DNA and direct sequencing of PCR products with aberrant electrophoretic patterns. Only one candidate mutation, G550R, caused by a GA transition, was detected in exon 14 of the pro-VWF gene sequence. This mutation was not found on 200 chromosomes of normal individuals. The propositus was homozygous for the mutation and for an extended intragenic haplotype, composed of eight polymorphic markers. Further family members were heterozygous for the mutation and were phenotypically normal or only mildly affected, in accordance with the recessive pattern of inheritance for VWD type IIC. The mutation could influence one of the presumed active centers for the suspected multimerizing enzymatic activity of pro-VWF localized in the D1 and D2 domain, which corresponds to exon 5 and exon 14 of the VWF gene.     

In vivo aromatization of [3H]testosterone in high and low mating lines of Japanese quail

Japanese quail selected bidirectionally for adult mating frequency were utilized to study in vivo aromatization of testosterone (T) in relation to masculine copulatory behavior. Functionally castrated high (HM) and low mating (LM) line quail were injected with 75 microCi of [3H]T. One hour after the injection, all radioactivity recovered in telencephalic-diencephalic brain tissue was in the form of T, dihydrotestosterone (DHT), or estradiol (E2). Neither the total 3H nor the [3H]T metabolite radioactivity differed between the two genetic lines. Of all [3H]T metabolic radioactivity, [3H]E2 represented 45 +/- 6 % in the HM line and 46 +/- 6% in the LM line, indicating that the line difference in mating frequency was not due to a corresponding difference in aromatase activity. Inasmuch as both the HM and LM line birds actively converted T to E2, these results implicate a neural mechanism involving E2-receptor interactions as the cause of the behavioral differences between the HM and LM lines.     

Cloning, nucleotide sequence, and expression of the flavodoxin gene from Desulfovibrio vulgaris (Hildenborough)

The gene coding for the flavodoxin protein from Desulfovibrio vulgaris (Hildenborough) has been identified, cloned, and sequenced. DNA fragments containing the flavodoxin gene were identified by hybridization of a mixed synthetic heptadecanucleotide probe to Southern blots of SalI-digested genomic DNA. The nucleotide sequences of the probe were derived from the published protein primary structure (Dubourdieu, M., LeGall, J., and Fox, J. L. (1973) Biochem. Biophys. Res. Commun. 52, 1418-1425). The same oligonucleotide probe was used to screen libraries (in pUC19) containing size-selected SalI fragments. One recombinant, carrying a 1.6-kilobase (kb) insert which strongly hybridizes to the probe, was found to contain a nucleotide sequence which codes for the first 104 residues of the amino-terminal portion of the flavodoxin protein sequence but lacked the remainder of the gene. Therefore, a PstI restriction fragment from this clone was used as a probe to isolate the entire gene from a partial Sau3AI library in Charon 35. Of the plaques which continued to hybridize strongly to this probe through repeated screenings, one recombinant, containing a 16-kb insert, was further characterized. The entire flavodoxin gene was localized within a 1.4-kb XhoI-SacI fragment of this clone. The complete nucleotide sequence of the structural gene for the flavodoxin protein from Desulfovibrio vulgaris and flanking sequences which may include promoter and regulatory sequences are reported here. The cloned flavodoxin gene was placed behind the hybrid tac promoter for overexpression of the protein in Escherichia coli. Modification to the 5'-end of the gene, including substitutions at the second codon, were required to obtain high levels of expression. The expressed recombinant flavodoxin protein is isolated from E. coli cells as the holoprotein with physical and spectral properties similar to the protein isolated from D. vulgaris. To our knowledge, this is the first example of the expression of a foreign flavodoxin gene in E. coli using recombinant DNA methods.     

2-Hydroxylation of estrogens in the brain participates in the initiation of the preovulatory LH surge in the rat

Estradiol-2-hydroxylase, the enzyme responsible for the conversion of estrogens to catechol estrogens was measured in the brain of female rats at specific stages of the estrus cycle. Radiometric measurements of the enzyme activity in microsomal, mitochondrial, and synaptosomal fractions of the brain revealed a sharp increased in activity at proestrus just prior to the preovulatory LH surge. The enzyme activity declined to lower levels at diestrus and metestrus. No comparable fluctuations were noted in the liver enzyme. These changes in brain enzyme activity in conjunction with demonstrated positive feedback of exogenous catechol estrogens on pituitary LH release, suggest that a rise in endogenous catechol estrogen formation in the brain may be responsible for the physiological induction of the preovulatory LH surge.     

Congenital dyserythropoietic anemia with ultrastructural features of type I and II.

The autopsy and electron microscopic findings in a pair of brothers with congenital dyserythropoietic anemia (CDA) are presented. In both patients autopsy revealed severe secondary hemochromatosis, including cirrhosis of the liver and fatal heart involvement. According to current ultrastructural criteria, a mixture of CDA type I (interchromatin bridges, wide euchromatin-cytoplasmic connections) and of type II (marginal cisternae, nuclear protrusions, multinuclearity, karyorrhexis) was found in erythroblasts of one patient. In the second patient electron microscopy of bone marrow stored in formalin for several years allowed the diagnosis of CDA with marginal cisternae in retrospect. These findings illustrate the usefulness of electron microscopy for the diagnosis of CDA in unsolved cases of chronic ineffective erythropoiesis, even from formalin fixed material. For subtyping CDA into type I and II, however, other than morphological parameters should be used for definition. In the clinical management splenectomy and a drastic phlebotomy programme have been found favourable.