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.     

Genetic localization of Hao-1, blind-sterile (bs), and Emv-13 on mouse chromosome 2.

The blind-sterile (bs) mutation in the mouse was localized on Chromosome 2 between Hao-1 and Emv-13. N2 progeny from a backcross between congenic female 129.AKR-bs Emv-13 mice and (129.AKR-bs/bs x Mus musculus molossinus) F1 male mice were typed by analysis of isozyme variants for Hao-1, visible inspection for bs, and restriction fragment length polymorphism for Emv-13 and Emv-15. Comparison between markers on mouse Chromosome 2 and corresponding markers on human chromosomes suggest that the human homolog of bs will be located on 20q11-q13.     

Factors influencing the landing of maleEpiphyas postvittana (Walker) exhibiting pheromone-mediated flight (Lepidoptera: Tortricidae)

The effects of changes in various visual and olfactory properties of a white card surface on the landing position of male Epiphyas postvittanaexhibiting pheromone-mediated flight were studied in a wind tunnel. Males landed predominantly at the most downwind position of a surface in line with the pheromone source, regardless of the strength of the source. The position on the surface that males landed was strongly influenced by visual factors. The landing position of males appeared to be influenced by visual cues along all three axes of the surface. Decreases in either the dimension horizontally perpendicular to the wind direction or the vertical dimension resulted in greater numbers of males landing farther upwind on the surface than the downwind edge. Visual changes in the axis along the wind direction also affected the position at which males landed. For example, when presented with two white card surfaces with a 4- cm gap between them, males tended to land on the downwind edge of the upwind surface (on which the source was located). When the gap was bridged with clear Mylar, the landing pattern was significantly different, with the greater proportion of males landing on the downwind surface. However, when Mylar was placed on the plexiglass floor of the tunnel (in addition to bridging the gap), the landing pattern on the surface was not significantly different from that on the two surfaces without the Mylar bridge. It is suggested that during the prelanding and landing phases of pheromone-mediated flight, male moths orient to visual features of the surface containing the pheromone source rather than to visual features of the source (conspecific female moth) itself.     

Induction of high-titer neutralizing antibodies, using hybrid human immunodeficiency virus V3-Ty viruslike particles in a clinically relevant adjuvant.

The localization of neutralization determinants within the envelope glycoproteins of human immunodeficiency virus (HIV) has been largely achieved by immunizing small animals in conjunction with Freund's adjuvant. However, for eventual use in humans, candidate HIV vaccine components must also be efficacious in a nontoxic formulation. We describe here the production of hybrid Ty viruslike particles carrying the major neutralizing domain of HIV and demonstrate the induction of high-titer virus-neutralizing antibodies and an HIV-specific T-cell proliferative response after immunization in conjunction with aluminum hydroxide. As aluminum hydroxide and aluminum phosphate are the only adjuvants currently licensed for use in humans, these observations have implications for the development of an effective vaccine against HIV.     

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.     

Rapid adjustment of guard-cell abscisic Acid levels to current leaf-water status

Detached broad bean (Vicia faba L.) leaflets were water stressed; within 15 minutes, guard-cell abscisic acid (ABA) concentration increased ninefold. This result eliminates the apparent discrepancy raised by reports of no correlation between initial water-stress effects on stomata and leaf ABA concentration. Six hours after stress relief, guard-cell ABA concentration was near the prestress value, which would seem to implicate other factors in stress aftereffects on stomata.     

Immunocytochemical localization of conglutin γ and legumin-like globulin in developing and mature seeds ofLupinus albus L.

Summary The distribution of two seed proteins, namely conglutin and a legumin-like globulin, in developing and mature seeds ofLupinus albus L. has been examined by immunocytochemistry and the concomitant modifications of their constituent polypeptides followed by SDS-PAGE. Both proteins were found within vacuolar protein bodies in various tissues of the cotyledons, although with some differences in the distribution patterns. The legumin-like protein was found to be deposited within the large storage parenchyma cells of the cotyledons in a manner similar to that reported for other storage proteins; little or no immunolabelling was associated with the cotyledonary epidermal and vascular parenchyma cells. In contrast conglutin was present in all cell types.A precursor of the legumin-like protein accumulated transiently in the developing cotyledon, but was subsequently modified by proteolytic cleavage. The onset of such modification was concomitant with a transition in the predominant vacuolar forms within the storage parenchyma cells. No precursor molecules of conglutin have been detected in this study, thus indicating that this protein is deposited in the protein bodies in its mature form.Abbreviations LM light microscopy - EM electron microscopy - DAF days after flowering - SDS-PAGE sodium dodecyl sulphate polyacrylamide gel electrophoresis - GAR goat antirabbit antiserum     

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.     

Bias in congenital malformations information from the birth certificate

An analysis of 1983 data from California birth certificates, and from the California Birth Defects Monitoring Program case registry, showed that there is a bias in reporting of congenital malformations on the birth certificate. Hospitals with many births erroneously report lower malformation rates than do hospitals with few births. The bias is partly due to the source of information; larger hospitals are more likely to get their information about malformations from the obstetrician than from the pediatrician. Since malformation data recorded on the birth certificate is both incomplete and biased, at present it is advisable to use these data for epidemiologic analyses with great caution.