Linkage disequilibrium analysis in Machado-Joseph disease patients of different ethnic origins

Machado-Joseph disease (MJD) is an autosomal dominant spinocerebellar degeneration originally described in families of Portuguese-Azorean ancestry. The hypothesis that its present world distribution could result from the spread of an original founder mutation has been raised. To test this possibility we have conducted a linkage disequilibrium study of markers segregating with the MJD1 locus in a total of 64 unrelated families of different geographical origins. Significant association was detected between the MJD1 locus and marker alleles at loci D14S280, D14S1050 and D14S81. All affected individuals, except one Chinese family, had allele 3 (237 bp) at D14S280. This finding is consistent with a founder effect in our MJD population. However, distinct haplotypes were observed in patients originating from the two Azorean islands showing the highest disease prevalence; therefore, the possible existence of more than one founder mutation can not be excluded with the markers currently available. Received: 27 February 1996 / Revised: 4 June 1996     

Dynamics of the sit-to-stand movement

The strategies of the sit-to-stand movement are investigated by describing the movement in terms of the topology of an associated phase diagram. Kinematic constraints are applied to describe movement sequences, thus reducing the dimension of the phase space. This dimensional reduction allows us to apply theorems of topological dynamics for two-dimensional systems to arrive at a classification of six possible movement strategies, distinguished by the topology of their corresponding phase portrait. Since movement is treated in terms of topological structure rather than specific trajectories, individual variations are automatically included, and the approach is by nature model independent. Pathological movement is investigated, and this method clarifies how subtle abnormalities in movement lead to difficulties in achieving a stable stance upon rising from a seated position. This article was processed by the author using the LAT_EX style file pljour2 from Springer-Verlag.     

A microdialysis study of the effects of the nicotinic agonist RJR-2403 on cortical release of acetylcholine and biogenic amines

Transcortical dialysis was employed to investigate the effects of subcutaneous (s.c.) injections of RJR-2403 (1.2–7.2 μmol/kg) on extracellular levels of acetylcholine (ACh), norepinephrine (NE), dopamine (DA), and serotonin (5-HT) in rat. Systemic administration of RJR-2403 produced a 90% increase of cortical extracellular ACh levels that persisted for up to 90 minutes after injection. Norepinephrine and DA release were increased 124% and 131% above basal values, respectively. Serotonin (5-HT) levels in the dialysate were also significantly elevated by RJR-2403 (3.6 μmol/kg, s.c.) 70% above baseline at 90 minutes post-injection. Comparison of these responses to those of (−)nicotine from a previous study reveals little difference between the two compounds in their ability to influence cortical neurotransmitter release following systemic administration.     

Allonia decandra: Floral remains of the tribeHamamelideae (Hamamelidaceae) from Campanian strata of southeastern USA

A single flower, detached anthers with in situ pollen grains, and isolated seeds from Campanian strata (Upper Cretaceous) of Georgia, southeastern USA, document the presence of plants assignable toHamamelidaceae in the Upper Cretaceous. The fossil flower is actinomorphic, pentacyclic and pentamerous. Irregular sepals are preserved as lobes of the floral cup, and petals are narrow, with parallel margins. The androecium has two whorls of functional stamens. Anthers are tetrasporangiate, dehisce through two valves, and have strongly elongate connective protrusions which converge over the center of the flower. The organizational and architectural features of the fossil document its affinity within subtribeLoropetalinae (Hamamelideae, Hamamelidoideae). Cladistic phylogenetic analyses using parsimony were conducted to explore the relationships between the fossil flower and extant genera of the tribeHamamelideae. The strict consensus of the four most parsimonious trees showsHamamelideae andLoropetalinae as well-supported monophyletic taxa. The fossil flower is clearly included within theLoropetalinae, and is placed as sister taxon to the southeastern Asian genusMaingaya. The occurrence of fossils assignable toLoropetalinae during the Campanian documents the existence ofHamamelidaceae with a level of floral organization and character evolution equivalent to that of extant genera, early in the evolutionary history of the family.     

Differential Expression of a Mycobacterium tuberculosis Protein Recognized by a Mouse Monoclonal Antibody

Murine monoclonal antibodies were produced against Mycobacterium tuberculosis (Mtb) using standard hybridoma procedures. By a whole cell enzyme-linked immunosorbent assay (ELISA), one monoclonal antibody (mAb), HB28, demonstrated high level specific reactivity to Mtb. Western blot analysis demonstrated reactivity to a single 65 kDa Mtb protein in the cell wall extract and culture filtrate. HB28 mAb appears to be recognizing a 65 kDa Mtb protein that is over-expressed by Mtb but not other species under certain culture conditions. Differential expression and detection of this protein by HB28 mAb may have potential for diagnostic applications.     

Substance P and neurokinin A metabolism by cultured human skeletal muscle myocytes and fibroblasts

A recent study determined that cultured human skeletal muscle adult myoblasts, myotubes, and fibroblasts degraded angiotensins and kinins via neutral endopeptidase-24.11 (NEP-24.11; EC 3.4.24.11) and aminopeptidase N (APN; EC 3.4.11.2). Due to the possible importance of other peptides to skeletal muscle blood flow and function, the present study looked specifically at the metabolism of the neurokinins substance P (SP) and neurokinin A (NKA) by skeletal muscle peptidases. The results show that SP is degraded not only by NEP-24.11, but also sequentially by dipeptidyl(amino)peptidase IV (DAP IV; EC 3.4.14.5)/APN. NKA is unaffected by DAP IV but is metabolized by NEP-24.11 and APN. NEP-24.11 was inhibited by phosphoramidon (IC₅₀ = 80 nM), thiorphan and ZINCOV, DAP IV by diprotin A (IC₅₀ = 8 μM), and APN by amastatin (IC₅₀ = 50 nM) and bestatin (IC₅₀ = 100 μM). Skeletal muscle myocyte and fibroblast metabolism of SP and NKA may regulate local skeletal muscle vascular and extravascular functions including SP- and NKA-mediated nerve-induced vasodilation. Inhibition of both NEP-24.11 and DAP IV/APN may increase skeletal muscle blood flow and decrease peripheral vascular resistance via potentiation of local neurokinin levels.     

Immunodetection of cytoskeletal structures and the Eg5 motor protein on deep-etch replicas of Xenopus egg cortices isolated during the cortical rotation

Summary— We have developed a new method for immunogold detection on deep-etch replicas of isolated Xenopus egg cortices in order to examine the interactions of different cortical elements in three dimensions at high resolution. We have applied this technique to vegetal cortices isolated during the second half of the first cell cycle. The vegetal cortical region at this time is the site of cellular machinery responsible for the ‘cortical rotation’. The entire cortex translocates with respect to the inner cytoplasm, relocating dorsalising determinants to the future dorsal side of the egg. The aligned microtubules in the shear zone between cytoplasm and cortex, implicated in the cortical rotation, were found to be organised as interweaving loose bundles. Interleaved amongst these aligned microtubules were extensive sheets of ER lying in layers parallel to the egg surface. Cytokeratin filaments were found to associate closely with the microtubules over short stretches. Putative actin filaments were present in the shear zone and in the cortex. Eg5, an abundant kinesin-related microtubule motor protein, and candidate for a role in generating cortical rotation movement, showed an almost exclusive localisation to microtubules. Immunofluorescence studies of cortices treated with detergent to disrupt ER or cold to depolymerise microtubules confirmed that Eg5 associates primarily with microtubules. We propose revised models for the mechanism of cortical rotation based on these observations and conclude that Eg5 is unlikely to move ER relative to microtubules during the cortical rotation.     

A non-canonical genetic code in an early diverging eukaryotic lineage.

The nearly invariant nature of the ''Universal Genetic Code'' attests to its early establishment in evolution and to the difficulty of altering it now, since so many molecules are required for, and depend upon, faithful translation. Nevertheless, variations on the universal code are known in a handful of genomes. We have found one such variant in diplomonads, an early-diverging eukaryotic lineage. Genes for alpha-tubulin, beta-tubulin and elongation factor 1 alpha (EF-1alpha) from two unclassified strains of Hexamitidae were found to contain TAA and TAG (TAR) triplets at positions suggesting a variant code in which TAR codes for glutamine. We found confirmation of this hypothesis by identifying genes encoding glutamine-tRNAs with CUA and UUA anticodons. The alpha-tubulin and EF-1alpha genes from two other diplomonads, Spironucleus muris and Hexamita inflata, were also sequenced and shown to contain no such non-canonical codons. However, tRNA genes with the anticodons UUA and CUA were found in H.inflata, suggesting that this diplomonad also uses these codons, albeit infrequently. The high GC content of these genomes and the presence of two isoaccepting tRNAs compound the difficulty of understanding how this variant code arose by strictly neutral means.     

Grass species and soil type effects on microbial biomass and activity

We evaluated plant versus soil type controls on microbial biomass and activity by comparing microbial biomass C, soil respiration, denitrification potential, potential net N mineralization and nitrification in different soils supporting four grass species, and by growing a group of 10 different grass species on the same soil, in two experiments respectively. In the first experiment, none of the microbial variables showed significant variation with grass species while all variables showed significant variation with soil type, likely due to variation in soil texture. In the second experiment, there were few significant differences in microbial biomass C among the 10 grasses but there were significant relationships between variation in microbial biomass C and potential net N mineralization (negative), soil respiration (positive) and denitrification (positive). There was no relationship between microbial biomass C and either plant yield or plant N concentration. The results suggest that 1) soil type is a more important controller of microbial biomass and activity than grass species, 2) that different grass species can create significant, but small and infrequent, differences in microbial biomass and activity in soil, and 3) that plant-induced variation in microbial biomass and activity is caused by variation in labile C input to soil.     

The effect of waxy mutations on the granule-bound starch synthases of barley and maize endosperms

The effects of waxy mutations on starch-granule-bound starch synthases (EC 2.4.1.18) in the developing endosperm of barley (Hordeum vulgare L.) and maize (Zea mays L.) have been investigated. Three granule-bound starch synthases in barley endosperm were identified by use of antibodies to known starch synthases, by reconstitution and assay of individual proteins from sodium dodecyl sulphate-polyacrylamide gels of granule-bound proteins, and by partial purification of proteins released by enzymic digestion of starch. These are proteins of 60, 77 and 90 kDa. Use of antibodies to known starch synthases and partial purification of proteins released by enzymic digestion of starch indicated that there may be at least four granule-bound starch synthases in maize endosperm: proteins of 59, 74, 77 and 83 kDa. Mutations at the waxy loci of both species affected only the 60- (barley) and 59-(maize) kDa isoforms. No evidence was found that other putative isoforms are altered in abundance or activity by the mutations. The contribution of our results to understanding of the starch synthase activity of intact starch granules and the mechanism of amylose synthesis is discussed.We are very grateful to Dr. Roger Ellis (SCRI, Dundee, Scotland) for the gift of barley seeds, and to Drs Roger Ellis, Alan Schulman and Cathie Martin for helpful advice and comments during the course of this work.