Sensitivity of an Acinetobacter baylyi mpl Mutant to DNA Damage

A mutant derived from Acinetobacter baylyi ADP1 was isolated from a screen for genes involved in the response to DNA damage. This derivative has an insertion in the mpl gene which encodes a peptidoglycan-recycling protein. We demonstrate that the insertion renders cells sensitive to mitomycin C and to UV.     

A covariotide model explains apparent phylogenetic structure of oxygenic photosynthetic lineages

The aims of the work were (1) to develop statistical tests to identify whether substitution takes place under a covariotide model in sequences used for phylogenetic inference and (2) to determine the influence of covariotide substitution on phylogenetic trees inferred for photosynthetic and other organisms. (Covariotide and covarion models are ones in which sites that are variable in some parts of the underlying tree are invariable in others and vice versa.) Two tests were developed. The first was a contingency test, and the second was an inequality test comparing the expected number of variable sites in two groups with the observed number. Application of these tests to 16S rDNA and tufA sequences from a range of nonphotosynthetic prokaryotes and oxygenic photosynthetic prokaryotes and eukaryotes suggests the occurrence of a covariotide mechanism. The degree of support for partitioning of taxa in reconstructed trees involving these organisms was determined in the presence or absence of sites showing particular substitution patterns. This analysis showed that the support for splits between (1) photosynthetic eukaryotes and prokaryotes and (2) photosynthetic and nonphotosynthetic organisms could be accounted for by patterns arising from covariotide substitution. We show that the additional problem of compositional bias in sequence data needs to be considered in the context of patterns of covariotide/covarion substitution. We argue that while covariotide or covarion substitution may give rise to phylogenetically informative patterns in sequence data, this may not always be so.      

Hemoglobin Fort Gordon or alpha2beta2145 Tyr replaced by Asp, a new high-oxygen-affinity hemoglobin variant.

Hemoglobin Fort Gordon, alpha2beta2145 Tyr replaced by Asp (HC2), has been observed in a 20-year-old black male with compensatory erythrocytosis. The variant was readily identified by electrophoresis and chromatography, and comprised about 30% of the red cell hemoglobin. The substitution was identified through analyses of tryptic peptides of various digests of the isolated beta chain. The oxygen affinity of whole blood was increased; two components were observed one of which had a greatly increased affinity for oxygen and a markedly reduced subunit cooperativity. It appears that the Tyr replaced by Asp substitution resembles the Tyr replaced by His substitution in hemoglobin Bethesda (Bunn, H. F. et al. (1972) J. Clin. Invest. 51, 2299-2309; Olson, J. S. and Gibson, G. H. (1972) J Biol. Chem. 247, 3662-3670; Adamson et al. (1972) J. Clin. Invest. 51, 2883-2888) in that both inhibit the quarternary change of the oxy to the deoxy conformation, resulting in greatly altered functional properties. Studies of a few members of the family were negative.     

Infant primate larynx: developmental histology.

Laryngeal epithelium of monkeys (M. mulatta, M. nemestrina) ranging in age from late fetal to adult was found to undergo the following developmental changes: (1) progressive elaboration of commissural epithelium prenatally, reaching the adult form of pseudostratified columnar ciliated epithelium early in the postnatal period;(2) vocal process epithelium changing from cuboid to stratified squamous tissue during the late prenatal period, and (3) progressive increments in overall epithelial thicknees during development, reaching a maximum in the early postnatal period. Chondrocyte density of the cricoid and thyroid cartilage decreased during the late prenatal period, reaching the adult form at the neonatal stage. The evidence suggests that mechanical or metaplastic stresses do not determine the observed tissue changes.     

Gonadal receptors. I. Evidence for irreversibility in the binding of human chorionic gonadotropin and human luteinizing hormone.

The binding of human chorionic gonadotropin and human luteinizing hormone to particulate receptors of rat testes has generally been assumed to follow an equilibrium model similar to that proposed for many enzyme systems. Our work shows that equilibrium dissociation constant (Kd) and number of hormone binding sites (Bmax) are highly sensitive to changes in hormone and/or receptor concentration and to treatment received by tissue or receptor preparation prior to the assay. The results of binding assays obtained using receptor preparation pretreated with hormone (labeled as well as unlabeled) indicated that the binding reaction between hormone and receptor was irreversible and that pretreatment of the tissue with hormone greatly alters the number of high affinity gonadotropin binding sites in the testicular homogenate. Data from studies involving increasing receptor concentrations revealed that increasing the mass of particulate receptors in the binding assays leads to higher Kd as well as Bmax values. These findings are incompatible with a binding model based upon occupancy of receptor sites and the state of equilibrium implied. The incompatibilities are analyzed and an alternate model advanced (Bhalla, V.K., Trowbridge, C.G., Chen, C.J.H., Lindeman, J.G. and Rojas, F.J. (1979) Biochim. Biophys. Acta 584, 436--453).     

Using ontologies to describe mouse phenotypes

The mouse is an important model of human genetic disease. Describing phenotypes of mutant mice in a standard, structured manner that will facilitate data mining is a major challenge for bioinformatics. Here we describe a novel, compositional approach to this problem which combines core ontologies from a variety of sources. This produces a framework with greater flexibility, power and economy than previous approaches. We discuss some of the issues this approach raises.     

Relationship between inflammatory cytology of canine seminal fluid and significant aerobic bacterial, anaerobic bacterial or mycoplasma cultures of canine seminal fluid: 95 cases (1987-2000)

Seminal fluid was collected by manual ejaculation from 95 dogs. Quantitative aerobic bacterial, qualitative anaerobic bacterial and mycoplasma cultures were performed on the seminal fluid, and their association with presence of inflammatory cells present in the pellet formed after centrifugation of the fluid was investigated. There was a clinically meaningful aerobic bacterial growth in 28.4%, anaerobic bacterial growth in 13.7%, and mycoplasma growth in 57.9% of the seminal fluid samples. Presence of inflammatory cytology was statistically associated with clinically meaningful aerobic bacterial growth. However, of the 78 dogs (82.1%) with clinically meaningful growth of at least one aerobic, anaerobic or mycoplasma organism, 43 (55.1%) had non-inflammatory seminal fluid cytology.