Expression of the alpha subunit of 7S nerve growth factor in the mouse submandibular gland

-NGF is an inactive serine protease that is associated in the mouse submandibular gland with a closely related serine protease, -NGF, and the neurotrophic factor, -NGF. The heterogeneity of purified -NGF has been examined by DEAE-cellulose chromatography and SDS polyacrylamide gel electrophoresis. A possible explanation for the observed heterogeneity is presented. Antibodies have been prepared against -NGF and purified by affinity chromatography so that they do not cross-react with -NGF. This antibody preparation recognizes two very similar proteins in male mouse submandibular gland RNA-directed cell-free translation mixtures. The expression of only one of these forms is regulated by testosterone. Oligonucleotide probes specific for each of the three NGF subunits have been prepared and used for Northern blot analysis of RNA from the mouse submandibular gland. The three subunits were found to be coordinately expressed and each were 30-fold more abundant in male than in female glands.Abbreviations used NGF nerve growth factor - -, -, and -NGF -, -, and -subunits of mouse 7S NGF - PBS phosphate buffered saline - DTT dithiothreitol - PPO 2,5-Diphenyloxazole - DMSO dimethylsulfoxide - HEPES N-2-Hydroxyethylpiperazine-N-2-ethanesulfonic acid - SSC 0.15M NaCl, 15 mM sodium citrate Supported by USPHS research grant NS19964. This paper is respectfully dedicated to Profs. Eric M. Shooter and Silvio Varon in recognition of their many contributions to our understanding of the structure and function of nerve growth factor.     

Clonal propagation of Callistemon by tissue culture techniques

Callus development in Callistemon viminalis was readily achieved when axillary buds derived from nodal tissue were placed in a medium containing macro- and micro-nutrients, sucrose (0.06 M), inositol (300 M), nicotinic acid (20 M), pyridoxine hydrochloride (3 M), thiamine hydrochloride (2 M), riboflavin (10 M), cytokinins (5 M) and auxins (0.1 M). The presence of benzylaminopurine (5 M) and p-chlorophenoxyacetic acid (0.1 M) promoted the most vigorous callus development and sprout formation. Rooting of nodal material was rare but occurred readily following the transference of sprouts developed on callus to a basal medium containing sucrose and salts. Root initiation was stimulated, however, by the presence of auxins. Chlorophenoxyacetic acid while stimulating root initiation repressed root growth. Indole butyric acid stimulated both root initiation and shoot growth at concentrations of 0.005 to 0.1 M. The treatment of choice for rooting and shoot growth was the addition of indole butyric acid at a concentration of 0.01 M.     

Quaternary uplifted coral reef terraces on Alor Island,East Indonesia

A flight of six major coral reef terraces, up to 700 m in altitude, occurs along the eastern and northern sides of Kabola Peninsula, Alor Island, Indonesia. Some radiometric dates have been obtained from unrecrystallized coral samples collected in growth position by three different methods (¹⁴C, ²³⁰Th/²³⁴U, ESR). This enabled the identification of the terraces corresponding to the Holocene and to oxygen-isotope stages 5c, 5e and 7. According to the present elevation of the dated terraces, a 1.0–1.2 mm/y mean rate of uplift can be discerned. Extrapolation of this trend to the whole sequence of terraces reveals a good correlation between the development of major terraces and interglacial or interstadial stages corresponding to astronomically calibrated oxygen isotope records, up to stage 13. The relatively rapid uplift rate in this region minimized the possibility of polycyclic sea-level stands at the same levels and contributed to the good preservation of some morphological reef features. Two superimposed marine notches are visible near the present shoreline, with retreat points at about 5.0 m and 8.6 m respectively above the present MLWST level. They can be interpreted as corresponding to a glacial interstadial (the upper notch) and to the Holocene sea-level peak (the lower one). As Holocene emergence has been less than what could be expected from a 1 mm/y rate of uplift, a major coseismic vertical displacement may occur in the future.This work is a contribution to the IGCP Project 367 Late Quaternary coastal records of rapid change and to the activities of the INQUA Commissions Neotectonics and Shorelines, the task group Paleoseismicity of the Late Holocene of the Inter-Union Commission on the Lithosphere, and the UNESCO-IUGS cooperative programme Earth Processes in Global Change (CLIP Pilot Project)     

Water column and sediment nitrogen and phosphorus distribution patterns in the Florida Keys,USA

Measurements of the distribution patterns of nutrients (ammonium, nitrate, orthophosphate, total N and total P) and chlorophyll concentrations were conducted under an interdisciplinary program known as SEAKEYS, initiated because of concern that anthropogenic nutrients may be impacting Florida coral reefs. Samples were collected along transects that extended from passes or canals to 0.5 km offshore of the outermost reefs. Seven of the transects were either in the Biscayne National Park (BNP) and Key Largo (upper keys) or Seven Mile Bridge/Looe Key (upper part of lower keys) areas, which have the best present-day reef development; the two in the middle keys off Long Key were in an area of minimal reef development where passes allow estuarine Florida Bay water to flow onto the Florida reef platform. Off the upper keys, water column concentrations of N and chl a were elevated near marinas and canals (1 M NO₃, 1 g/l chl a), but returned to oligotrophic levels (e.g., chl a 0.25 g/l; NO₃ 0.25 M; NH₄ 0.10 M) within 0.5 km of shore. Phosphorus concentrations, however, were often higher offshore 0.2 M PO₄). Sediment interstitial nutrient concentrations decreased from inshore to the offshore reef areas (e.g., 100 M NH₄ inshore to 50 M NH₄ offshore) and were comparable to those of some presumably pristine coastal and reef carbonate sediments. Sediment bulk N was higher nearshore and decreased steeply offshore ( 60 g-at N/gm sediment to 20 g-at N/gm sediment, respectively); bulk P concentrations ( 6 g- at P/gm sediment) varied little or exhibited the reverse pattern. Sediment N:P ratios were consistently lower offshore (1–10 vs. 20–40 nearshore). Higher offshore P concentrations are attributed to periodic upwelling along the shelf edge. In the middle keys water column nutrients and chl a concentrations were both higher than those in the upper keys, and there was less of an inshore-offshore decrease than that noted in the upper keys. Sediment nutrients were higher also, and nearshore and offshore areas did not differ. Water column and sediment nutrient concentrations and distribution patterns in the upper part of the lower keys were most similar to those measured in the upper keys. Overall, the present data do not support the contention that reef areas in the upper keys are accumulating elevated loads of land-derived nutrients via surface water flow, but does document moderately elevated nutrient and chl a levels in many developed nearshore areas. Most of the anthropogenic and natural nutrients entering the coastal waters from shore appear to be taken up by near shore algal and seagrass communities before they reach patch reef areas. Further work is needed to determine whether nutrient-enriched ground waters reach the reefs, however these would be expected to cause an enrichment of reef sediments, which was not observed.     

Sialidase of swine influenza A viruses: variation of the recognition specificities for sialyl linkages and for the molecular species of sialic acid with the year of isolation

The sialidase of swine influenza A viruses of N1 and N2 subtypes, isolated from 1930 to 1992, was studied for substrate specificity with ganglio-series, lacto-series type II and GM3 gangliosides containing Neu5Ac2-3Gal, Neu5Gc2-3Gal and Neu5Ac2-6Gal linkages. All viral sialidases tested showed that the activity for hydrolysing substrates with Neu5Ac2-3Gal was higher than the activities with Neu5Gc2-3Gal and Neu5Ac2-6Gal linkages. When GM1b, GM3 and sialylparagloboside were used as substrates, the earliest strain (A/Wisconsin/15/30 H1N1, isolated in 1930) showed the activity ratio of Neu5Ac2-6Gal to Neu5Ac2-3Gal to be 0.13:0.2, and the ratio Neu5Gc2-3Gal/Neu5Ac2-3Gal to be 0.19:0.37, while those strains isolated from 1978 to 1992 exhibited ratios of 0.29:0.58 for Neu5Ac2-6Gal/Neu5Ac2-3Gal and 0.51:0.76 for Neu5Gc2-3Gal/Neu5Ac2-3Gal. The above results indicate that the substrate specificities of sialidases from swine influenza A viruses towards sialyl linkages and the molecular species of sialic acid are related to the year of isolation, i.e. strains isolated after 1978 exhibited higher activity towards Neu5Ac2-6Gal and Neu5Gc2-3Gal linkages when compared with strains isolated in an earlier year, 1930.Abbreviation Neu5Ac 5-N-acetylneuraminic acid - Neu5Gc 5-N-glycolyneuraminic acid - Gal d-galactose - Glc d-glucose - Cer Ceramide - II³(Neu5Ac)Lac Neu5Ac2-3Gal1-4Glc - GM3(Neu5Ac2-3Gal) Neu5Ac2-3Gal1-4Glc1-Cer - GM3(Neu5Gc2-3Gal) Neu5Gc2-3Gal1-4Glc1-Cer - GM1b(Neu5Ac2-3Gal) Neu5Ac2-3Gal1-3GalNac1-4Gal1-4Glc1-Cer - GMlb(Neu5Gc2-3Gal) Neu5Gc2-3Gal1-3GalNAc1-4Gal1-4Glc1-Cer - IV³(Neu5Ac)nLc4Cer Neu5Ac2-3Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - IV³(Neu5Gc)nLc4Cer Neu5Gc2-3Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - IV⁶(Neu5Ac)nLc4Cer Neu5Ac2-6Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - TDC taurodeoxycholate.     

Effect of α(2–6)-linked sialic acid and α(1–3)-linked fucose on the interaction ofN-linked glycopeptides and related oligosaccharides with immobilizedPhaseolus vulgaris leukoagglutinating lectin (L-PHA)

The effects of branching and substitution of branches by sialic acid and fucose on the interaction ofN-linked glycopeptides and related oligosaccharides with immobilizedPhaseolus vulgaris leukoagglutinating lectin (L-PHA) were examined. Asialo bi-, tri-and tetra-antennary glycans were all retarded but to different extents on a long column of L-PHA-agarose. Asialo tri- and tetra-antennary glycans containing the pentasaccharide unit Gal1-4GlcNAc1-2[Gal1-4GlcNAc1-6]Man were strongly retarded, whereas asialo bi- and tri-antennary glycans lacking the Gal1-4GlcNAc1-6 branch were only weakly retarded. In all instances the interaction with the lectin was completely abolished when either (2–6)-linkedN-acetylneuraminic acid or (1–3)-linked fucose was present at the galactose orN-acetylglucosamine residue of the Gal1-4GlcNAc1-6Man1-6 branch, respectively. The same substitutions on the Gal1-4GlcNAc1-6Man1-6 branch decreased but did not abolish the affinity of the lectin for the glycans. The presence of NeuAc2-6 and Fuc1-3 on the other two branches did not interfere with the binding of the glycans to L-PHA. Furthermore, it appeared that the presence of the Man1-4GlcNAc unit is requried for interaction with the lectin. In order to obtain reliable information on the relative occurrence of tri- and tetra-antennary glycopeptides, this study shows that it is essential to desialylate and to defucosylate the glycans prior to application to L-PHA-agarose.Abbreviations L-PHA leukoagglutinating phytohemagglutinin - CMP-NeuAc cytidine-5-monophospho-N-acetylneuraminic acid - GP glycopeptide - OS oligosaccharide - HPLC high-performance liquid chromatography - FNR fraction not retarded - FR fraction retarded suffixes MS, BS and TS indicate mono-, bi- and trisialyl derivatives respectively; suffix MF indicates monofucosyl derivatives.structures of the substratesOS2, OS3, OS3, OS4, GP2, GP3, GP4, GP4-MF, OS2(3) andOS2(-) are presented in Fig. 2     

Interactions of Aβ(1–40) with Glycerophosphocholine and Intact Erythrocyte Membranes: Fluorescence and Circular Dichroism Studies

Deposition of amyloid peptide in human brain in the form of senile plaques is a neuropathological hallmark of Alzheimers disease (AD). Levels of a phospholipid breakdown product, glycerophosphocholine (GPC), also increase in AD brain. The effect of GPC on amyloid (1–40) peptide (A) aggregation in PBS buffer was investigated by circular dichroism and fluoresence spectroscopy; interactions of A and GPC with the intact erythrocyte membrane was examined by fluoresence spectroscopy. Fluorescamine labeled A studies indicate GPC enhances A aggregation. CD spectroscopy reveals that A in the presence of GPC adopts 14% more -sheet structure than does A alone. Fluorescamine anisotropy measurements show that GPC and A interact in the phospholipid head-group region of the erythrocyte membrane. In summary, both soluble A and GPC insert into the phospholipid head-group region of the membrane where they interact leading to -sheet formation in soluble A which enhances A aggregation.     

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. (Apicomplexa: Eimeriidae) from the black-capped bulbul,Pycnonotus xanthopygos

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. are described from the black-capped bulbul Pycnonotus xanthopygos from Lincoln Park Zoo, Chicago, Illinois. The bird came from southwestern Africa seven years earlier. I. ernsti oocysts are ellipsoidal to bluntly ovoid, 28–38 × 23–31m (mean 34 × 28 m) and have a single-layered oocyst wall. Micropyle, oocyst residuum and polar granules are absent. Sporocysts are elongate ovoid, 24–30 × 11–16 m (mean 27×13 m). Stieda and substiedal bodies and sporocyst residuum are present. I. blagburni oocysts are spherical to subspherical. 21–28 × 19–26 m (mean 25 × 23 m) and have a single oocyst wall. Sporocysts are ovoid and 17–23 × 10–13 m (mean 20 × 12 m). Stieda and substiedal bodies and sporocyst residuum are present.     

Micropropagation and ecorestoration of Vanda spathulata,an exquisite orchid

Node explants collected from flowering plants of Vanda spathulata, an endemic and exquisite orchid of Peninsular India and Sri Lanka, were cultured in Mitra medium with combinations of 4.4–88.8 m 6-benzyl adenine (BA) and 0.0–114.2 m indole-3-acetic acid (IAA). Combinations of 44.4 m BA with 17.1 or 28.5 m IAA and 66.6 mM BA with 28.5 or 40.0 m IAA induced maximum formation of 12.6 and 12.1 shoots / node, respectively, in a 6-month period. Subcultured nodal explants produced maximum of 6.1 shoots at combinations of 22.2–44.4 m 21 BA and 5.7–28.5 m IAA. Rooting of shoots occurred in medium containing 75 g l^–1 banana pulp and 5.7 m IAA within 3–9 weeks. Plantlets of 2–5 cm length possessing two to five roots established easily in community pots at 80–90% rates without hardening. Community potted plants introduced into forest segments at Ponmudi and Palode in Southern Western Ghats of India established at a rate of 50–70%.     

Silver staining the chromosome scaffold

Cytological silver-staining procedures reveal the presence of a core running along the chromatid axes of isolated HeLa mitotic chromosomes. In this communication we examine the relationship between this core and the nonhistone chromosome scaffolding, isolated and characterized in previous publications from this laboratory. When chromosomes on coverslips were subjected to the steps used for scaffold isolation in vitro and subsequently stained with silver, the characteristic core staining was unaffected. Control experiments suggested that the core does not contain large amounts of DNA. When scaffolds were isolated in vitro, centrifuged onto electron microscope grids, and stained with silver, they were found to stain selectively under conditions where specific core staining was observed in intact chromosomes. These results suggest that the nonhistone scaffolding is the principal target of the silver stain in chromosomes.     

Extracellular matrix proteins,integrin receptors (VLA-β1, VLA-α2 and VLA-α5) and growth fraction in atypical macroregenerative nodules of the liver: an immunocytochemical case study

A case of cirrhotic liver harbouring three atypical macroregenerative nodules and an hepatocellular carcinoma was immunocytochemically investigated for the expression of VLA- 1, VLA-2 and VLA-5 integrins and for different extracellular matrix (ECM) components (collagen I, collagen IV, laminin, fibronectin and tenascin). In addition, the proliferative activity within the nodules was evaluated, using the MIB 1 monoclonal antibody (MAb). The cirrhotic liver disclosed a continuous staining pattern of the ECM proteins investigated, as well as a sinusoidal immunostaining of VLA-1, VLA-2 and VLA-5. The macroregenerative nodules showed a discontinued immunoreactivity for ECM proteins while maintaining a VLA-1 sinusoidal immunostaining, coupled with intercellular immunostaining. VLA-2 and VLA-5 expression was lacking. The growth fraction was low in both the above pathological conditions. The hepatocellular carcinoma was devoid of any ECM immunostaining. VLA-1 immunoreactivity exhibited a honeycomb pattern of staining, whereas VLA subunits were absent. MIB1 expression was high, being present in 30% of neoplastic nuclei. A possible relationship between atypical macroregenerative nodules and hepatocellular carcinoma is discussed.This paper was partly presented at the 35th Symposium of the Society for Histochemistry, Gargellen, Austria, Sept. 29–Oct. 3, 1993     

Conservation status of parrot populations in an Atlantic rainforest area of southeastern Brazil

A census of four species of syntopic parrots was carried out using distance sampling methods on São Sebastião island, SE Brazil. Most of the 33593 ha island is covered by mature and secondary Atlantic rainforest. Almost 80% of these forests are within the Ilhabela Park. Although the species counted have marked differences in size and weight, density (individuals/km²) and estimated population size in 23500 ha of well-preserved forests were similar: Amazona farinosa (13.82±5.94; 3247±1395), Pionus maximiliani (15.79±7.04; 3712±1654), Brotogeris tirica (15.05±4.87; 3537±1143) and Pyrrhura frontalis (13.06±5.53; 3068±1298). Encounter rates of Forpus crassirostris and Pionopsitta pileata were very low, which suggests that there is only a small population of these species on the island. The São Sebastião forests still support healthy populations of parrots. Although woodpecker population estimates on the island are large enough to provide nesting sites for parrots, competition for holes with other secondary cavity nesters such as toucans, flycatchers and tytiras, and the selective cutting of dead trees for canoe construction, which is a common practice on the island, may limit hole availability for parrots.     

Moral commitment without objectivity or illusion: Comments on Ruse and Woolcock

Peter Woolcock, in Ruse's Darwinian Meta-Ethics: A Critique, argues that the subjectivist (nonobjectivist) Darwinian metaethics proposed by Michael Ruse (in Taking Darwin Seriously) cannot work, because the illusion of objectivity that Ruse claims is essential to morality breaks down when it is recognized as illusion, and there then remain no good reasons for acknowledging or following moral obligations. Woolcock, however, is mistaken in supposing that moral behaviour requires rational motivation. Ruse's Darwinian metaethical analysis shows why such objective support for morality is neither plausible nor necessary; and when that is recognized, it can also be seen that Ruse's proposed illusion of moral objectivity is superfluous.     

The dynamic effects of inputs to spinal motoneurones of different type upon the outputs of γ-motoneurones mediated via recurrent inhibition

A previous dynamic model of the spinal motoneurone-Renshaw cell system has been extended by integrating -motoneurones (-MNs), which are also supposed to represent Ia inhibitory interneurones mediating reciprocal inhibition. For the recurrent inhibition of -MNs, two cases are considered: -MNs inhibiting themselves via Renshaw cells (RCs), and -MNs not subjected to self-inhibition. Two input systems are taken into account: monosynaptic Ia input distributed inhomogeneously to the three types of -MNs (S, FR, and FF), and spinally descending input from the lateral vestibular nucleus distributed inhomogeneously to the three -MN types and to -MNs. Dynamic input-output relations have been calculated in form of Bode or polar plots. The main results are: Input signals (Ia and VST) to -MNs are transmitted via RCs to -MNs with high-pass characteristics (lower cut-off around 1 Hz). The relatively high gains at high frequencies are attenuated more or less strongly by recurrent self-inhibition of -MNs depending on the overall strength of recurrent inhibition. The phase lags of -MNs with respect to the input are not frequency-independent, but vary between about-90° and-180° (at times up to-200°). To preserve in-phase activation of -and -MNs, certain criteria have to be met which are discussed in terms of additional input systems to -MNs and RCs.     

Trois nouveaux Nadejdolepis Spasskii & Sasskaya, 1954 (Cestoda: Hymenolepididae) parasites de Charadrii (Aves) de Tasmanie

Three species of Nadejdolepis from Tasmania, Australia, are described and illustrated. N. burgessi n. sp., a parasite of Charadrius ruficapillus, is 4-6 mm long, with rostellar nitiduloid hooks 63-66 m long, a short evaginated cirrus 13-16 m long with a short collar of thin spines 1 m long, a narrow and tubular sclerotinoid vagina 40-50 long and 3-4 m in diameter with a little ampulla 3-5 m in diameter at the proximal end, and a membranous atrial segment with smooth, short (1 m) and compact spines which are sometimes difficult to observe. N. smithi n. sp., a parasite of 40-50 long and 3-4 m in diameter with a little ampulla 3-5 m in diameter at the proximal end, and a membranous atrial segment with smooth, short (1 m) and compact spines which are     

Expectancy influence on self-reported experience during alpha feedback training

From a screening questionnaire, 12 subjects indicating some prior knowledge of alpha training (but no actual biofeedback training experience) and 12 subjects lacking such prior knowledge were selected for two 30-minute feedback sessions, one providing an opportunity to enhance and the other to suppress EEG alpha. Written self-reports of experiential state were independently rated by two judges on a five-point scale (Walsh, 1974) according to the degree to which they approximated alleged alpha vs. nonalpha experiences. These self-reports indicated that only the subjects expressing prior knowledge were able to differentiate between the enhancement and suppression sessions. A second study explored whether knowledgeable subjects (presumably those with positive expectancies) could make a similar differentiation when their expectancies regarding the type of feedback they would receive were manipulated. Twenty subjects received enhancement and 20 others received suppression feedback for four 40-minute sessions. Within each of these groups, 10 subjects were led to believe they enhanced alpha, and 10 were told they suppressed alpha. Half the subjects, therefore, believed they were attempting to change alpha in a direction opposite that of their actual task. Both actual and expected direction of alpha change significantly affected self-reports in the expected direction. Seemingly, situational expectancy alone was not sufficient to account for the actual feedback effects in the knowledgeable subjects. It is not entirely clear whether the alpha-related experiences reported by these knowledgeable subjects were responses to internal (i.e., physiologic state) or subtle external cues.     

An ecological approach to biosystem thermodynamics

The general attributes of ecosystems are examined and a naturally occurring reference ecosystem is established, comparable with the isolated system of classical thermodynamics. Such an autonomous system with a stable, periodic input of energy is shown to assume certain structural characteristics that have an identifiable thermodynamic basis. Individual species tend to assume a state of least dissipation; this is most clearly evident in the dominant species (the species with the best integration of energy acquisition and conservation). It is concluded that ecosystem structure results from the antagonistic interaction of two nearly equal forces. These forces have their origin in the Principle of Most Action (least dissipation or least entropy production) and the universal Principle of Least Action. Most action is contingent on the equipartitioning of the energy available, through uniform interaction of similar individuals. The trend to Least action is contingent on increased dissipation attained through increasing diversity and increasing complexity. These principles exhibit a basic asymmetry. Given the operation of these opposing principles over evolutionary time, it is argued that ecosystems originated in the vicinity of thermodynamic equilibrium through the resonant amplification of reversible fluctuations. On account of the basic asymmetry the system was able to evolve away from thermodynamic equilibrium provided that it remained within the vicinity of ergodynamic equilibrium (equilibrium maintained by internal work, where the opposing forces are equal and opposite).At the highest level of generalization there appear to be three principles operating: i) maximum association of free-energy and materials; ii) energy conservation (deceleration of the energy flow) through symmetric interaction and increased homogeneity; and iii) the principle of least action which induces acceleration of the energy flow through asymmetrical interaction. The opposition and asymmetry of the two forces give rise to natural selection and evolution.     

The occurrence of the chloroplast pyrenoid is correlated with the activity of a CO2-concentrating mechanism and carbon isotope discrimination in lichens and bryophytes

The organic-matter carbon isotope discrimination () of lichens with a wide range of photobiont and/or cyanobiont associations was used to determine the presence or absence of a carbon-concentrating mechanism (CCM). Two groups were identified within the lichens with green algal photobionts. One group was characterised by low, more C₄-like values ( < 15), the other by higher, more C₃-like values ( > 18). Tri-partite lichens (lichens with a green alga as the primary photobiont and cyanobacteria within internal or external cephalodia) occurred in both groups. All lichens with cyanobacterial photobionts had low values ( < 15). The activity of the CCM, organic-matter values, on-line values and gas-exchange characteristics correlated with the presence of a pyrenoid in the algal chloroplast. Consistent with previous findings, lichens with Trebouxia as the primary photobiont possessed an active CCM while those containing Coccomyxa did not. Organic values for lichens with Stichococcus as the photobiont varied between 11 and 28. The lichen genera Endocarpon and Dermatocarpon (Stichococcus + pyrenoid) had C₄-like organic values ( = 11 to 16.5) whereas the genus Chaenotheca (Stichococcus — pyrenoid) was characterised by high C₃-like values ( = 22 to 28), unless it associated with Trebouxia ( = 16). Gas-exchange measurements demonstrated that Dermatocarpon had an affinity for CO₂ comparable to those species which possessed the CCM, with K_0.5 = 200–215 1 · 1^–1, compensation point () = 45–48 l · l^–1, compared with K_0.5 = 195 1 · 1^–1, = 441 · 1^–1 for Trebouxioid lichens. Furthermore, lichens with Stichococcus as their photobiont released a small pool (24.2 ± 1.9 to 34.2 ± 2.5 nmol · mg^–1 Chl) of inorganic carbon similar to that released by Trebouxioid lichens [CCM present, dissolved inorganic carbon (DIC) pool size = 51.0 ± 2.8 nmol · mg^–1 Chl]. Lichens with Trentepohlia as photobiont did not possess an active CCM, with high C₃-like organic values ( = 18 to 23). In particular, Roccella phycopsis had very high on-line values ( = 30 to 33), a low affinity for CO₂ (K_0.5 = 400 1 · 1^–1, = 120 1 · ^–1) and a negligible DIC pool. These responses were comparable to those from lichens with Coccomyxa as the primary photobiont with Nostoc in cephalodia (organic = 17 to 25, on-line = 16 to 21, k_0.5 = 388 1 · 1^–1, = 85 1 · 1^–1, DIC pool size = 8.5 ± 2.4 nmol · mg^–1 Chl). The relative importance of refixation of respiratory CO₂ and variations in source isotope signature were considered to account for any variation between on-line and organic . Organic was also measured for species of Anthocerotae and Hepaticae which contain pyrenoids and/or Nostoc enclosed within the thallus. The results of this screening showed that the pyrenoid is correlated with low, more C₄-like organic values ( = 7 to 12 for members of the Anthocerotae with a pyrenoid compared with = 17 to 28 for the Hepaticae with and without Nostoc in vesicles) and confirms that the pyrenoid plays a fundamental role in the functioning of the CCM in microalgal photobionts and some bryophytes.Abbreviations and Symbols CCM carbon-concentrating mechanism - DIC dissolved inorganic carbon (CO₂ + HCO ₃ ^- + CO ₃ ^2- ) - DW dry weight - K_0.5 external concentration of CO₂ at which half-maximal rates of CO₂ assimilation are reached - photobiont photosynthetic organism present in the lichen - Rubisco ribulose-1,5-bisphosphate carboxylase-oxygenase - carbon isotope discrimination (%) - ¹³C carbon isotope ratio (%) This research was funded by Natural Environment Research Council grant no. GR3/8313. The authors would also like to thank Dr. B. Coppins, Royal Botanic Gardens Edinburgh and Prof. A. Roy Perry, National Museum of Wales, for access to herbarium collections, Dr. T. Booth for confocal microscopy work and Dr. A.J. Richards, University of Newcastle upon Tyne and Dr. O.L. Gilbert, University of Sheffield for identifying bryophytes and lichens respectively. E.S. would particularly like to thank Dr. M. Broadmeadow, The Forestry Authority, Farnham, Surrey, and Cristina Máguas, Universidade de Lisboa, for their advice and expertise at the beginning of the project.     

Self-consistent 3J coupling analysis for the joint calibration of Karplus coefficients and evaluation of torsion angles

The concept of self-consistent J coupling evaluation exploits redundant structure information inherent in large sets of 3J coupling constants. Application to the protein Desulfovibrio vulgaris flavodoxin demonstrates the simultaneous refinement of torsion-angle values and related Karplus coefficients. The experimental basis includes quantitative coupling constants related to the polypeptide backbone torsion originating from a variety of heteronuclear 2D and 3D NMR correlation experiments, totalling 124 3J(HN,H), 129 3J(HN,C), 121 3J(HN,C), 128 3J(Ci–1,Hi), 121 3J(Ci–1,Ci), and 122 3J(Ci–1,Ci). Without prior knowledge from either X-ray crystallography or NMR data, such as NOE distance constraints, accurate dihedral angles are specified for 122 non-glycine and non-proline residues out of a total of 147 amino acids. Different models of molecular internal mobility are considered. The Karplus coefficients obtained are applicable to the conformational analysis of torsions in other polypeptides.     

Involvement of β 1,4 galactosyltransferase 1 and Galβ 1→4GlcNAc groups in human hepatocarcinoma cell apoptosis

1,4 galactosyltransferase 1 ( 1,4GT1) synthesizes Gal 14GlcNAc groups in N-linked sugar chains of animal glycoproteins, which have been demonstrated to play an important role in many biological events, including sperm-egg interaction, cell migration and mammalian embryonic development. In this study, the mRNA level of 1,4GT1 was found to increase greatly during the 7721 hepatocarcinoma cells apoptosis induced by cycloheximide. Ricinus Communis Agglutinin-I staining indicated generous increase of Gal 14GlcNAc groups during apoptosis. Further study showed that the 7721 hepatocarcinoma cells transiently transfected with 1,4GT1 were more susceptible to the apoptosis induced by cycloheximide. The increased susceptibility was in accordance to the transfection concentration of 1,4GT1, which also led to the increased Gal 14GlcNAc groups on the transfected cell surface. All the observations suggested that 1,4GT1 and Gal 14GlcNAc groups might be associated with the apoptosis of human hepatocarcinoma cells.