Phylogenetic relationships in Maloideae (Rosaceae): evidence from sequences of the internal transcribed spacers of nuclear ribosomal DNA and its congruence with morphology

We used sequences from both internal transcribed spacers (ITS) and a small portion of the 5.8S gene of nuclear ribosomal DNA (nrDNA) for phylogenetic reconstruction of 19 genera of Maloideae and four potential outgroups from the Rosaceae. Parsimony analyses indicate that Maloideae are not monophyletic; Vauquelinia, which is traditionally placed in Spiraeoideae, and two genera of the Maloideae, Eriobotrya and Rhaphiolepis, form a well-supported clade that is the sister to the remainder of the subfamily. Although our ITS phylogenetic hypothesis is highly resolved, there is considerable homoplasy, and support, as indicated by bootstrap values and decay indices, is relatively weak for all groups except four: Eriobotrya-Rhaphiolepis-Vauquelinia, Crataegus-Mespilus, Amelanchier-Peraphyllum-Malacomeles, and Cydonia-Pseudocydonia. Our DNA sequence data do not support a broad interpretation of Sorbus. Intergeneric hybridization, which is prevalent in Maloideae, occurs between genera that are far removed from one another on our most-parsimonious trees. We infer an overall phylogeny from separate analyses of ITS DNA sequences and recently published morphological and wood anatomical studies of Maloideae and from analyses after pooling these data sets. The four most strongly supported clades of the ITS phylogeny appear in the phylogeny based on pooled data.     

Linkage of early-onset osteoarthritis and chondrocalcinosis to human chromosome 8q.

Calcium pyrophosphate-deposition disease (CPDD), also called "chondrocalcinosis" or "pseudogout," is a disorder characterized by the deposition of calcium-containing crystals in joint tissue, which leads to arthritis-like symptoms. The presence of these crystals in joint tissue is a common finding in the elderly, and, in this population, there is a poor correlation with joint pain. In contrast, early-onset CPDD has been described in several large families in which the disease progresses to severe degenerative osteoarthritis (OA). In these families, an autosomal dominant mode of inheritance is observed, with an age at onset between the 2d and 5th decades of life. In this report, we describe a large New England family with early-onset CPDD and severe degenerative OA. We found genetic linkage between the disease in this family and chromosome 8q, with a multipoint lod score of 4.06. These results suggest that a defective gene at this location causes the disease in this family.     

Protein-free models for the proton-coupled reduction of haemoproteins

Reduction of the bis-pilocarpate-haemin complex at pH greater than or equal to 10 involves the simultaneous uptake of an electron by the Fe(III) ion and a proton by the pendant alkoxide group of an axial ligand. This provides a protein-free model for reactions such as the proton-coupled reduction of cytochromes which involve cooperative Coulombic interaction between two non-bonded sites.     

Novel kinetic and structural properties of the class-I D-fructose 1,6-bisphosphate aldolase from Escherichia coli (Crookes'' strain).

Investigation of aldolase 1, the class-I D-fructose 1,6-bisphosphate aldolase (EC4.1.2.13) from Escherichia coli (Crookes' strain), showed it to have unusual kinetic and structural properties. The enzyme appeared to be larger than was previously supposed and may be a decamer with a mol. wt. of approx. 340000. Its fructose 1,6-bisphosphate-cleavage activity was unaffected by these compounds. The enhancement exhibited a strong dependence on pH. These novel kinetic properties do not seem to be shared by any other fructose 1,6-bisphosphate aldolase, but recall the activation by polycarboxylic acids of the deoxyribose 3-phosphate aldolases from some other organisms. In view of its unusual properties, it is unlikely that aldolase 1 from E. coli is closely related to the class-1 aldolases that have been detected in several other prokaryotes, or to the typical class-1 enzymes from eukaryotes.     

Effects of Combinations of Substrates on Maximum Growth Rates of Several Rumen Bacteria

Five rumen bacteria, Selenomonas ruminantium, Bacteroides ruminicola, Megasphaera elsdenii, Butyrivibrio fibrisolvens, and Streptococcus bovis were grown in media containing nonlimiting concentrations of glucose, sucrose, maltose, cellobiose, xylose and/or lactate. Each bacterium was grown with every substrate that it could ferment in every possible two-way combination. Only once did a combination of substrates result in a higher maximum growth rate than that observed with either substrate alone. Such stimulations of growth rate would be expected if specific factors unique to individual substrates (transport proteins and/or enzymes) were limiting. Since such synergisms were rare, it was concluded that more general factors limit maximum growth rates in these five bacteria.     

A spectroscopic study of metal ion and ligand binding to β-lactamase II

β-Lactamase II has two metal-binding sites. The electronic spectra of Cd(II)- and Co(II)-substituted β-lactamase II have been investigated. It is suggested that a thiol ligand is involved in metal binding at the first site. The stoichiometric dissociation constants for Co(II) binding to β-lactamase II were estimated to be 0.13 and 2.66 mM (pH 6.0, 4°C, 1 M NaCl) by equilibrium dialysis. Competition between Zn(II) and Co(II) for the first metal binding site suggests a value of 0.7 μM (pH 6.0, 30°C, 1 M NaCl) for the dissociation constant o Zn(II).The electronic spectra of the Co(II) enzyme lead to the suggestion that the coordination geometries around the metal ions in the first and second sites are related to those of a distorted tetrahedron and octahedron, respectively.     

The rate of interconversion between the two unfolded forms of ribonuclease A does not depend on guanidinium chloride concentration.

The interconversion between the fast-folding and slow-folding forms of ribonuclease A is unaffected by the protein denaturant guanidinium chloride, between 2.8 m and 7.0 m, at 10 °C. Thus the rate of this reaction is insensitive to denaturants, in contrast to the model proposed by Kanehisa &; Tsong (1979). This result is consistent with other evidence that the interconversion reaction is proline isomerization.