Twelve loci form a continuous linkage map for human chromosome 18

We have constructed a primary genetic map of human chromosome 18 consisting of 11 DNA markers and one serological marker (JK). Two of these loci define highly polymorphic VNTR systems. The markers define a continuous genetic linkage map of 97 cM in males and 205 cM in females; female genetic distances in a panel of 59 three-generation families were consistently about twice those observed in males. The high odds in support of the linear order of the markers on this recombination map, and the extent of coverage of chromosome 18, indicate that this map will permit efficient linkage studies of human genetic diseases that may be segregating on chromosome 18 and will provide anchor points for development of high-resolution maps for this chromosome.     

Feedback delays and relaxation expectancies in EMG biofeedback

The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yield results confounded by differential expectancies for relaxation. Furthermore, the role of expectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects of feedback delays and induced relaxation expectancies on EMG activity and experienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one of four computerized feedback delay conditions (0.0037, 0.7493, 2.2481, 6.7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affecting EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expectancies. Instrumental and expectancy factors in EMG biofeedback appear to operate independently of each other by reducing physiological activity and producing psychological relaxation respectively.This study was completed by the first author under the direction of the second author in partial fulfillment of the requirements for the Master of Arts degree. We gratefully acknowledge the computerization advice and assistance provided by Larry Wheeler, and the assistance in data collection provided by Dawn Dexter and Michael Winstanley.     

Long-term vegetation change in the Juncus squarrosus grassland at Moor House,northern England

Data from the long-term experiment on sheep grazing versus zero sheep grazing (i.e. in an enclosure) on the composition of the Juncus squarrosus grassland at the Moor House NNR are presented. The data have been analysed to assess change in (1) the abundance of individual species, (2) higher plant and bryophyte communities, and (3) vegetation structure. The higher plant data suggested that both the enclosed-and grazed plots were changing in the same direction, but the enclosed plot was moving much faster. The general tendency was towards a blanket bog vegetation dominated by Eriophorum vaginatum and Calluna vulgaris. Juncus squarrosus has declined very quickly in the enclosed plot, but there has also been a slower decline in the grazed one. A significant increase in Calluna vulgaris has occurred only in the enclosed plot. In contrast, the bryophyte data showed completely different successional trajectories in the two treatment plots.The vegetation structure changed markedly after release from grazing, with a decrease in phytomass, but increase in necromass in the lowest height strata. There was no noticeable change in structure over the 18 year period in the grazed plot.Particular problems found in this study were that some species either fluctuated widely in response, or changed in a curvilinear manner.     

A 7000-year pollen record from the Amazon lowlands,Ecuador

The longest continuous Amazonian palynological record (ca 7010 yrs B.P. to present) from Lake Ayauchⁱ, Ecuador, reveals species-by-species abundance changes during a period of climatic change. Pollen influx from a wet tropical rain forest was found to be high, 1×10⁴–10⁵ grains cm^-2 yr^-1, although mature forest taxa were poorly represented. Horizons of laminated sediments and weathered gyttja, dated to ca 4200–3150 B.P., evidence a period of reduced net water availability. During this period Ficus, Alchornea and Palmae pollen representation appears to decline, although there is no evidence of a major forest compositional change. The lake was reduced to a shallow, possibly seasonal, pool. Zea cultivation was recorded between ca 2850 B.P., (the earliest paleoecological record to date in the Amazon basin) and ca 800 B.P. It is suggested that Zea was cultivated on exposed lake sediment within the crater at times of low water levels. The abandonment of Zea cultivation may have been due to rising water levels or social unrest.     

Ultrastructural and morphometric analysis of long-term peripheral nerve regeneration through silicone tubes

Brain Cell Biology - Light and electron microscopy were used to investigate long-term regeneration in peripheral nerves regenerating across a 10 mm gap through silicone tubes. Schwann cells and...     

Structure-function analysis of hepatocyte growth factor: identification of variants that lack mitogenic activity yet retain high affinity receptor binding.

Hepatocyte growth factor (HGF) is a potent mitogen for parenchymal liver, epithelial and endothelial cells. Structurally, it has similarities to kringle-containing serine proteases, although it does not possess proteolytic activity. A structure-activity relationship study of human HGF was performed by functional analysis of HGF substitution and deletion variants. Analysis of HGF variants was accomplished by defining their ability to induce DNA synthesis on hepatocytes in primary culture and to compete with wild-type HGF for binding to a soluble form of the HGF receptor. Three groups of variants were made: (i) substitutions at the cleavage site, (ii) substitutions within the protease-like domain and (iii) deletions of the beta-chain and/or kringle domains. Our results show that: (i) single-chain HGF is a zymogen-like promitogen in that cleavage into a two-chain form is required for biological activity, however, the single chain form of HGF still retains substantial receptor binding capacity; (ii) certain mutations in the protease-like domain result in variants that are completely defective for mitogenic activity, yet exhibit apparent receptor binding affinities similar to wild-type HGF (Kd approximately 50-70 pM); and (iii) a variant containing the N-terminal 272 residues of mature HGF showed only a 4-fold increase in Kd when compared with wild-type HGF indicating that a primary receptor binding determinant is located within this sequence.     

Electric organ polyamines and their effects on the acetylcholine receptor

1. The electric organ of Torpedo nobiliana contained putrescine (PUT), spermidine (SPD), spermine (SPM), and cadaverine (CAD). Traces of acetylated SPD and SPM were occasionaly seen. 2. Upon fractionation of the tissue by differential centrifugation, the polyamines (PA) were found predominantly in the soluble fraction. The postsynaptic membrane fraction, containing a high concentration of acetylcholine receptor (AChR), was proportionally enriched in SPM. The molar ratio of SPM to AChR was approximately two in these membranes. 3. The effect of exogeneous PA on AChR function was studied by two methods: carbamoylcholine (CCh)-dependent 86Rb+ influx into receptor-rich membrane vesicles and [alpha-125I]bungarotoxin (Bgt) binding to the AChR. 4. SPM inhibited both ion influx and the rate of Bgt binding at concentrations above 1 mM, and therefore it appears to act as a competitive antagonist of the AChR. 5. At submicromolar concentrations, and only after preincubation with the receptor-rich membrane, SPM and PUT increased the ion influx by about 20% over control values. 6. Preincubation with 100 nM SPM did not affect the equilibrium binding of iodinated toxin or the rate of toxin binding, and therefore SPM was not uncovering new receptors. 7. By measuring the initial rate of toxin binding after different periods of preincubation with 1 microM CCh, the rate of the slow phase of receptor desensitization was determined. This rate was not changed by 100 nM SPM. 8. Although these results suggest that at low concentrations SPM is a positive modulator of the AChR, the precise mechanism of action is not determined yet.     

Radical functionalism: The life and work of Karl Polanyi

Conclusion In concluding, let us restate the main theoretical arguments concerning Austria-Hungary and Malinowski-Polanyi. There are many more aspects of this latter contrast which I have not dwelt on, including those of temper and personality. My concern was to show that it is not enough to trace ideas back to their origin in an undifferentiated Central Europe, for we need to be quite clear about the context in which those ideas were initially taken on board. Mach was an appropriate philosopher for the ordered bureaucracy of Austria, and he embodies the individual-centered and fundamentally conservative message, which I see articulated later in very different (and non-positivist) styles by Popper, Hayek, Schumpeter, etc. This was the message accepted in its fundamentals by Malinowski in Cracow. The Hungarian half of the Empire had quite different traditions, and one might even say that political dilemmas in this half of the Empire were so pressing that they had no time for philosophy. By the time Polanyi was growing up in Budapest, nationalist fervor was at its height, and a nineteenth century heritage of liberal, even radical thought, was under pressure from the extreme right. Polanyi's Jewish family background probably pushed him towards the Left in his early years, though it in no way interfered with this Hungarian patriotism. When he read Mach, he accepted the individualist and positivist aspects of the message, but he could never endorse the conservative respect for tradition that underpinned Malinowski's functionalism. This is what makes his position so interesting, and he maintained it throughout his career.In this light, Polanyi's economic anthropology is an authentic cultural product of Central Europe. Malinowski, to the extent that he took on board the basic social theory of Austrian liberal conservatism, sold out to the West, and to an ideological tradition which has an alternative home in another country on the periphery of industrial capitalism: Enlightenment Scotland. Austria-Hungary also produced intellectuals who sold out in the other direction, and abandoned all notion of intellectual autonomy for the individual by capitulating to the total discipline of the revolutionary Party. This tradition is that of Russia and Lenin, and the best known Central European intellectual recruit was Lukács, perhaps because he studied idealists in Germany rather than the positivists in Vienna. Karl Polanyi was unable to give unswerving loyalty either to the capitalist ideology of the West, or to the ideology of the new tributary mode of production in the East. The middle position, which I believe he occupied throughout his life, is one that will never satisfy ideologues, and it is hard to infuse it with the same intellectual elegance. Still, just as his historical researches showed the real possibilities for combining modes of economic integration, and his life experiences showed the folly of concentration on only one, so Hungarians have learned from history that they are best off with the sort of mixed economy they have today. His popularity in Hungary is therefore unsurprising, and one may hope that the practical message of his anthropology will not be permanently forgotten in the West.Christopher H. Hann is a Professor of Social Anthropology, University of Kent, Canterbury.     

Characterization oftrans-acting regulatory elements affecting the expression of Mn-superoxide dismutase (sodA) inEscherichia coli

Escherichia coli strains harboringtrans-acting mutations affecting the expression of Mn-superoxide dismutase (SOD) gene (sodA) were used to studysodA regulation. Complementation studies revealed that eitherarc (aerobic respiratory control) orfur (ferric uptake regulation) loci independently complemented anaerobic expression of asodA::lacZ protein fusion in one mutant strain (UV16). This mutant exhibited phenotypes (i.e., elevated outer membrane proteins, enzyme activity, and dye sensitivity) typical offur andarc mutants. When these mutations were introduced into an otherwise wild-type background, anaerobicsodA expression occurred only when botharc andfur mutations were present simultaneously, suggesting cooperative roles of Fur and Arc insodA repression. The reconstructedfur arcA andfur arcB double mutants were still inducible by iron chelators, suggesting the possible involvement of another iron-containing repressor protein. A second independent mutant strain harboring atrans-acting regulatory mutation (UV14) was only partially complemented by multicopy plasmids carryingfur ⁺ orarc ⁺ genes, implicating other genetic elements insodA regulation.