Disruption of pattern formation in palatal rugae in fetal mice heterozygous for First arch (Far)

The purpose of this study was to document the extent of disruption in the pattern of palatal rugae caused by the presence of one copy of the First arch mutation. The palatal ruga pattern was found to be disrupted in 86% of 15- to 17-day mouse fetuses that were heterozygous for the First arch mutation in the ICR/Bc strain, compared with 9% in ICR/Bc fetuses of normal (+/+) genotype. This new observation in First arch heterozygotes, together with the previously reported dominant effects of the First arch mutation, particularly the bifurcation of the maxillary nerve (100% in both BALB/cGaBc and ICR/Bc strains), the disruption of maxillary vibrissa pattern (80% in ICR/Bc), and the hemifacial deficiency (38% in ICR/Bc), has led us to redefine the First arch mutation as a semidominant, Far. Like the other defects caused by Far, the rugal defects are in tissue derived from the embryonic maxillary prominence. The rugal defects observed in +/Far palates were always asymmetrical and most often involved fragmentation and misalignment of two or more of rugae 4-7. The relatively large degree of variation in ruga pattern observed in fetuses of normal genotype suggests that it is a less well canalized trait than the normal pattern of maxillary vibrissae which varies only in a few very specific and minor ways. The First arch mutation, which in heterozygotes disrupts pattern formation in both palatal rugae and maxillary vibrissae, can be used to study genetic control of pattern formation in mammalian embryos.     

Atrial granules contain an amino-terminal processing enzyme of atrial natriuretic factor

At least three enzymes have been identified in atrial tissue homogenates that are capable of processing pro-atrial natriuretic factor to active atrial peptides. The atrial peptides possess potent natriuretic, diuretic, vasorelaxant, and hemodynamic properties, and their existence has implicated the mammalian heart as an endocrine organ. We have purified and characterized a serine proteinase (Mr approximately equal to 70,000) associated with atrial granules that preferentially hydrolyzes the Arg-Ser bond in the synthetic substrates Gly-Pro-Arg-Ser-Leu-Arg, benzoyl-Gly-Pro-Arg-Ser-Leu-Arg, and benzoyl-Gly-Pro-Arg-Ser-Leu-Arg-Arg-2-naphthylamide, the Arg-2-naphthylamide bond in the substrate benzoyl-Gly-Pro-Arg-2-naphthylamide, and the Arg-Ser bond in a 31-residue substrate (Gly96-Tyr126 peptide) corresponding to residues Arg98-Ser99 in pro-atrial natriuretic factor. The Gly96-Tyr126 peptide contains the putative processing site in pro-atrial natriuretic factor and the sequence for the bioactive peptides. Our results indicate that the minimum processing site sequence is -Gly-Pro-Arg-Ser-Leu-Arg-Arg- and that the Ser99-Tyr126 natriuretic peptide is the predominant hydrolytic product. After prolonged incubation or at high enzyme concentrations, the Ser103-Tyr126 natriuretic peptide may also be formed. The Ser103-Arg125 natriuretic peptide was only a very minor product. The doublet of basic amino acids is not the primary processing site in pro-atrial natriuretic factor, but their presence may influence cleavage at the single Arg residue "upstream." Our findings are consistent with the idea that the pro-protein and the processing enzymes are packaged into the secretory granule and in response to the proper stimulus, the pro-protein is processed to the active peptides, probably during the process of secretion. The processing pathway of pro-atrial natriuretic factor is discussed.     

A method for analysis of back shape in scoliosis

The shape of the back is an important factor in the clinical assessment of various spinal disorders, in particular scoliosis. A method of analysis of back surface shape is described which was designed to present most of the numerical parameters needed to assess the progress of the disease as it affects body shape. Measurements of back surface shape and manually marked anatomical landmarks were taken from a television/computer surface measurement system in which a plane of light was scanned over the back and from moiré topographs. The anatomical landmarks were used to define reference planes from which successive analyses were matched. Asymmetry in the transverse plane was illustrated by horizontal cross-sections and skin surface angles. The lateral deformity was shown by an estimate of the line of the vertebral bodies beneath the skin, derived by adding an extra lateral displacement to the palpated positions of the spinous processes, proportional to the rotation of the skin in the transverse plane. This model was used to estimate vertebral end-plate angles and Cobb angles. Lateral sections showed kyphosis and lordosis. Correlations of Lateral Asymmetry from the surface shape analysis with Cobb angle from X-ray measurements in three groups of patients (totalling 119 subjects) were in the range r = 0.77 to r = 0.94, p less than 0.0001. The analysis has reduced follow-up X-ray examinations at the Nuffield Orthopaedic Centre because it indicates quantitatively and with complete safety both lateral asymmetry and deformity in the transverse plane.     

Molecular modeling to predict the structural and biological effects of mutations in a highly conserved histone mRNA loop sequence.

The 3'-end of histone mRNAs contains a highly conserved sequence motif which is believed to form a 6 base pair stem and a 4 base loop. These sequences are involved in both the efficiency of 3'-end formation and stability of the mature histone mRNA. We have modeled four stem basepairs and the loop portion of this structure using the wildtype sequences and several mutant sequences. A structure for the wildtype stem-loop is proposed that is based on energy minimization using a representative wildtype sequence and comparison with structures obtained using naturally occurring mutations which do not alter loop function. A wildtype structure is proposed in which the top basepair of the stem is broken, forming a six base loop. Mutant sequences with altered bases in the loop and in the stem were also modeled. The effect of these mutations on the proposed wildtype structure is discussed and possible biological consequences considered.     

The gene for autosomal dominant polycystic kidney disease lies in a 750-kb CpG-rich region.

PKD1, the locus most commonly affected by mutations that produce autosomal dominant polycystic kidney disease (ADPKD), has previously been localized to chromosome 16p13.3. Since no cytogenetic abnormalities have been found in association with ADPKD, flanking genetic markers have been required to define an interval--the PKD1 region--that contains the PKD1 gene. In this report we demonstrate, through the construction of a long-range restriction map that links the flanking genetic markers GGG1 (D16S84) and 26.6PROX (D16S125), that the PKD1 gene lies within an extremely CpG-rich 750-kb segment of chromosome 16p13.3. Approximately 90% of this region has been cloned in three extensive cosmid/bacteriophage contigs. The cloned DNA is a valuable resource for identifying new closer flanking genetic markers and for isolating candidate genes from the region.     

Active transport of ATP and presence of a vanadate-sensitive membrane-bound ATPase in Mycobacterium leprae.

It is not known how Mycobacterium leprae obtains energy for survival and growth in the host tissues; the organism does not grow in vitro. In the studies reported here, M. leprae incorporated labelled ATP, which was blocked by cyanide, unlabelled ATP or ADP, but not by adenosine or Pi. It seems that the organism takes up unhydrolysed ATP by an active transport process. The bacterium contained a membrane-bound, vanadate-sensitive E1 E2-ATPase (which creates a transmembrane potential driving transport of solutes into cells). The enzyme was not inhibited by N-ethylmaleimide, suggesting that it is not an F0F1-ATPase which catalyses ATP synthesis. Apparently, M. leprae derives energy-rich compounds from the host cell.     

Normal mouse strains differ in the site of initiation of closure of the cranial neural tube

The scanning electron microscopic study of day 9 embryos reported here documents differences among normal mouse strains in morphology of cranial neural tube closure. The site of initiation of contact and fusion of the cranial neural folds, previously defined as Closure 2 (Macdonald et al., '89), is located in the region of the junction between the forebrain (prosencephalon) and midbrain (mesencephalon) in three normal strains: LM/Bc, AEJ/RkBc, and ICR/Bc. However in a fourth normal strain, SWV/Bc, Closure 2 is initiated much further rostral, in the prosencephalic region. In addition, the anterior neuropore, rostral to Closure 2, closes late in ICR/Bc embryos, relative to the posterior progress of development of the Closure 2 seam. Initiation of closure from the most rostral end of the neural tube (Closure 3) appears to be relatively delayed in ICR/Bc embryos. We hypothesize that the observed genetic polymorphism in location of the first site of fusion between the cranial neural folds in normal mouse embryos may be one basis for differences among normal strains in liability to exencephaly induced by teratogens.