Phylogenetic relationships among species of Prunus as inferred by isozyme markers

Summary An isozyme survey of 34 species of Prunus representing subgenera Prunus, Amygdalus, Cerasus, and Lithocerasus detected 110 presumptive alleles at 11 isozyme loci. Principal component analysis was conducted on the covariance matrix derived from allelic frequencies calculated for each species. Cluster analysis was performed on the first 30 principal components. Results generally support traditional classification of Prunus at the subgeneric level, except for members of subgenus Lithocerasus and two members of subgenus Amygdalus. Prunus glandulosa Thunb., P. japonica Thunb., and P. tomentosa Thunb. of subgenus Lithocerasus and P. triloba Lindl. of subgenus Amygdalus appear to represent primitive species. P. besseyi Bailey and P. pumila L. of subgenus Lithocerasus and P. andersonii of subgenus Amygdalus should be assigned to subgenus Prunus. Placement of its members indicates that subgenus Lithocerasus is an artificial grouping of species that are very different genetically although similar phenotypically.Paper No. 12529 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7643, USA     

Study of water and oil diffusion in rape seeds with sorption-desorption and NMR techniques.

The sorption and desorption of water in rape seeds was measured. From the sorption isotherm it follows that for water content greater than about 6% the water molecules tend to form clusters. The mutual diffusion coefficient of water into and out of the seeds was determined from the time dependence of sorption and desorption. There is a pronounced hysteresis in the sorption-desorption process, desorption proceeds faster than sorption. The self-diffusion of water (at maximum humidity of the seeds) and oil within the seeds was investigated by the pulsed field gradient NMR. The measurement of oil self-diffusion shows restricted diffusion of the oil within droplets and allows the determination of the droplet radii and their distribution width.     

An abundant and ubiquitous homo-oligomeric ring-shaped ATPase particle related to the putative vesicle fusion proteins Sec18p and NSF.

We have discovered a ring-shaped particle of 12.5 nm diameter, 14.5S and apparent molecular weight of approximately 570,000 that displays 6-fold radial symmetry and is composed of a single kind of an acidic (pI approximately 5.5) polypeptide of Mr 97,000 (p97). Using antibodies to this protein we have detected its occurrence in a wide range of cells and tissues of diverse species from frog to man, including highly specialized cells such as mammalian erythrocytes and spermatozoa. In Xenopus laevis oocytes, the particle is found in both isolated nuclei and in manually enucleated ooplasms, which corresponds to immunofluorescence staining dispersed over both nucleoplasm and cytoplasm. The particle has a N-ethylmaleimide (NEM)-inhibitable Mg2(+)-ATPase activity, and its amino acid sequence, as deduced from cDNA clones, displays considerable homology to the mammalian NEM-sensitive fusion protein (NSF) and yeast Sec18p believed to be essential for vesicle fusion in secretory processes, indicating that these three proteins belong to the same multigene family.     

Structural and functional characterization of the gamma 1 subunit of GABAA/benzodiazepine receptors.

The GABAA receptor gamma 1 subunit of human, rat and bovine origin was molecularly cloned and compared with the gamma 2 subunit in structure and function. Both gamma subunit variants share 74% sequence similarity and are prominently synthesized in often distinct areas of the central nervous system as documented by in situ hybridization. When co-expressed with alpha and beta subunits in Xenopus oocytes and mammalian cells, the gamma variants mediate the potentiation of GABA evoked currents by benzodiazepines and help generate high-affinity binding sites for these drugs. However, these sites show disparate pharmacological properties which, for receptors assembled from alpha 1, beta 1 and gamma 1 subunits, are characterized by the conspicuous loss in affinity for neutral antagonists (e.g. flumazenil) and negative modulators (e.g. DMCM). These findings reveal a pronounced effect of gamma subunit variants on GABAA/benzodiazepine receptor pharmacology.     

Cyclophilin A is required for the replication of group M human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus SIV(CPZ)GAB but not group O HIV-1 or other primate immunodeficiency viruses.

The human immunodeficiency virus type 1 (HIV-1) Gag polyprotein binds to cyclophilin A and incorporates this cellular peptidyl prolyl-isomerase into virions. Disruption of cyclophilin A incorporation, either by gag mutations or by cyclosporine A, inhibits virion infectivity, indicating that cyclophilin A plays an essential role in the HIV-1 life cycle. Using assays for packaging of cyclophilin A into virions and for viral replication sensitivity to cyclosporine A, as well as information gleaned from the alignment of Gag residues encoded by representative viral isolates, we demonstrate that of the five lineages of primate immunodeficiency viruses, only HIV-1 requires cyclophilin A for replication. Cloned viral isolates from clades A, B, and D of HIV-1 group M, as well as a phylogenetically related isolate from chimpanzee, all require cyclophilin A for replication. In contrast, the replication of two outlier (group O) HIV-1 isolates is unaffected by concentrations of cyclosporine A which disrupt cyclophilin A incorporation into virions, indicating that these viruses are capable of replicating independently of cyclophilin A. These studies identify the first phenotypic difference between HIV-1 group M and group O and are consistent with phylogenetic studies suggesting that the two HIV-1 groups were introduced into human populations via separate zoonotic transmission events.     

The ultrastructure of the cuticle of Nematoda

 The ultrastructure of the body cuticle in species of six of seven representative genera of Stilbonematinae (Eubostrichus, Catanema, Laxus, Robbea, Leptonemella, and Stilbonema) was investigated using SEM and TEM techniques. Additionally, one species of Spirinia (Spiriniinae) and one of Desmodora (Desmodorinae) were studied for outgroup comparison. The body cuticle of all investigated stilbonematids shows a consistent pattern composed of specific elements in a characteristic arrangement to each other. This pattern does not occur in Stilbonematinae alone, but also in Desmodorinae and Spiriniinae. Furthermore, a comparison within the Desmodorida reveals that this cuticular pattern apparently is present in the cuticle of representatives of Monoposthiidae, Epsilonematidae, and Draconematidae. The present results lead to the following conclusions: (1) the cuticle of Stilbonematinae contains no autapomorphic characters for this taxon, (2) there is a common cuticular pattern within the Desmodorida, and (3) this pattern is an autapomorphic character for the order Desmodorida. Accepted: 4 February 1996