The major protein of pancreatic zymogen granule membranes (GP-2) is anchored via covalent bonds to phosphatidylinositol

GP-2, the major integral protein characteristic of the pancreatic zymogen granule membrane can be released from the membrane by the action of a phosphatidylinositol specific phospholipase C (PI-PLC). In a hydrophobic/hydrophilic phase separation system using the non-ionic detergent Triton X-114, the membrane-bound form of the protein went from the detergent phase into the hydrophilic phase upon action of the phospholipase. PI-PLC solubilization of GP-2 unmasked an antigenic determinant similar to the cross-reacting determinant of the trypanosome variant surface glycoproteins. This determinant being a distinctive feature of the glycan moiety of phosphatidyl-inositol anchored membrane proteins, it established the glycosyl-phosphatidyl-inositol nature of the GP-2 membrane anchor. Since soluble GP-2 is also found in the contents of the granule and is secreted intact into the pancreatic juice, it is likely that one of the mechanisms responsible for its release could be a specific phospholipase. GP-2 is the first glycosyl-phosphatidyl-inositol-anchored protein that is integral to the membrane of an organelle and not located at the surface of the cell.     

Surgical excision of an ameloblastic odontoma in a cynomolgus monkey (Macaca fascicularis)

A surgical approach used for removal of maxillary tumors in humans was modified to excise a maxillary tumor in a cynomolgus monkey (Macaca fascicularis). This is an effective technique for excising tumors, recovering fractured canine teeth, or other health problems of the maxillary region in Macaca sp. The described approach limits facial disfigurement and enhances the probability of return to required function for future research utilization. This approach minimizes the extensive degree of post-operative intensive care.     

An Autosomal Genetic Linkage Map of the Sheep Genome

We report the first extensive ovine genetic linkage map covering 2070 cM of the sheep genome. The map was generated from the linkage analysis of 246 polymorphic markers, in nine three-generation fullsib pedigrees, which make up the AgResearch International Mapping Flock. We have exploited many markers from cattle so that valuable comparisons between these two ruminant linkage maps can be made. The markers, used in the segregation analyses, comprised 86 anonymous microsatellite markers derived from the sheep genome, 126 anonymous microsatellites from cattle, one from deer, and 33 polymorphic markers of various types associated with known genes. The maximum number of informative meioses within the mapping flock was 222. The average number of informative meioses per marker was 140 (range 18-209). Linkage groups have been assigned to all 26 sheep autosomes.     

Does limb length predict the relative energetic cost of locomotion in mammals?

Do relatively longer limbs result in a lower energetic cost of locomotion? To determine whether or not cost is correlated with limb length in some way other than that due to their respective relationships to body mass, we have removed the effects of size by calculating the residuals of the relationship between each character and body size. We then regressed the pairs of residuals on one another. Because biological variables do not occur in a series of units that have evolved independently, the degree of divergence of two species is likely to be influenced by the length of time since they last shared a common ancestor. We therefore corrected for the phylogenetic relatedness of species. Data on the energetic cost of locomotion of a wide variety of species were taken from published sources. Data on limb lengths were taken from specimens in various museum collections which were similar in body mass (± 12%) to the specimens on which the cost measurements were made. None of the correlations between the residuals of either fore- or hindlimb length and neither of two estimates of the cost of locomotion was significant at P = 0.05. It is concluded that limb length does not importantly influence an animal's locomotor efficiency. These results do not imply the lack of a close relationship between cost and stride length.     

Enhancement of Neurospora VS ribozyme cleavage by tuberactinomycin antibiotics.

Several examples of inhibition of the function of a ribozyme or RNA-protein complex have shown that certain antibiotics can interact specifically with RNA. There are, however, few examples of antibiotics that have a positive, rather than a negative, effect on the function of an RNA. We have found that micromolar concentrations of viomycin, a basic, cyclic peptide antibiotic of the tuberactinomycin group, enhance the cleavage of a ribozyme derived from Neurospora VS RNA. Viomycin decreases by an order of magnitude the concentration of magnesium required for cleavage. It also stimulates an otherwise insignificant transcleavage reaction by enhancing interactions between RNA molecules. The ability of viomycin to enhance some RNA-mediated reactions but inhibit others, including translation and Group I intron splicing, demonstrates the potential for natural selection by small molecules during evolution in the 'RNA world' and may have broader implications with respect to ribozyme expression and activity in contemporary cells.     

Pores formed in lipid bilayers and in native membranes by nodularin,a cyanobacterial toxin

Nodularin (NODLN), a cyclic pentapeptide hepatotoxin from the cyanobacterium Nodularia spumigena, induces pores in bilayers of diphytanoyl lecithin (DPhL) and in locust muscle membrane. NODLN increases the surface pressure of a DPhL monolayer; except when the surface pressure of the monolayer is high when the toxin causes a reduction of this parameter. NODLN pores exhibit many open conductance states; the higher state probabilities increasing when the transmembrane pressure is increased. The results from these studies are discussed in terms of two models for a NODLN pore, a torroidal model and a barrel-stave model. The edge energy of the NODLN pore of 1.4× 10^–12 J/m is determined.Abbreviations NODLN Nodularin - MCYST-LR Microcystin-LR - ADDA 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid - DPhL diphytanoyl lecithin Correspondence to: A. G. Petrov     

The diagnosis and recommendation integrated system (DRIS) for diagnosing the nutrient status of grassland swards: II. Model calibration and validation

A DRIS model for perennial ryegrass, based on data collected from a glasshouse experiment, was used to diagnose the nutrient sufficiency status of perennial ryegrass swards growing in field situations. Initially, DRIS overestimated the N and P status of these swards and underestimated their S status. However, by calibrating the model outputs on the basis of actual sward dry matter yield responses to specific fertiliser inputs, correction factors were evaluated, and the nutrient indices modified to reflect the nutritional status of swards in field situations.Modified DRIS diagnoses of the N, P, K and S status of swards were compared with those made using the critical value approach. DRIS proved to be as reliable as the critical value approach at diagnosing N deficiency (both approaches having reliability scorings of 90%), but was superior to the latter at diagnosing P, K and S deficiencies, having reliability scorings of 100% (P), 90% (K) and 70% (S), compared with scorings of only 0% (P), 80% (K) and 30% (S), for the critical value approach.     

A consensus linkage map for swine chromosome 7

The First International Workshop on Swine Chromosome 7 (SSC7) was held in Minnesuing, Wisconsin, USA on 21–24 September 1995. The objective was to develop a comprehensive linkage map for porcine chromosome 7 by combining genotypic data from four swine reference populations. Contributions of genotypic data were made from the US Meat Animal Research Center, the University of Minnesota, the PiGMaP consortium and the Scandinavian consortium. Primers for selected sequence tagged site markers, to be genotyped across the reference populations, were exchanged to integrate individual maps of SSC7. Eighty-six loci were genotyped; these loci represented microsatellite, minisatellite, single-strand conformation polymorphism, restriction fragment length polymorphism, erythrocyte antigen and protein polymorphisms. Eighteen genes were mapped, including 12 markers within class I, class II and class III regions (four markers in each class) of the swine major histocompatibility complex. Forty-two markers were either genotyped on more than one population or were included in a haplotype system and used to develop skeletal linkage maps that spanned 147·6, 212·7 and 179·5 cM for the male, female and sex-average maps, respectively. A comprehensive linkage map was developed incorporating those markers with more than 30 informative meioses. The comprehensive map was slightly longer than the skeletal map, at 153·3, 215·3 and 183·8 cM, respectively, with only three intervals greater than 10 cM. These results significantly improve the genetic resolution of the porcine chromosome 7 map and represent an accurate approach for the merging of genetic maps produced in different reference populations.