Showing papers by "University of Dundee published in 1987"
TL;DR: The results show that a common, bicyclic protein kinase cascade can potently inactivate the regulatory enzymes of both fatty acid and cholesterol biosynthesis.
563 citations
TL;DR: An enzyme‐linked fluorometric assay is described for the continuous monitoring of the unidirectional efflux of glutamate from guinea‐pig synaptosomes, consistent with an intrasynaptosomal relocation of the amino acid.
Abstract: An enzyme-linked fluorometric assay is described for the continuous monitoring of the unidirectional efflux of glutamate from guinea-pig synaptosomes. Glutamate efflux from freshly suspended, polarized synaptosomes occurs at 0.35–0.39 nmol min−1 mg of protein−1 and is not significantly affected by external Ca2+. KC1 depolarization (30 mM KCI) in the absence of Ca2+ doubles this rate, whereas in the presence of Ca2+, the initial kinetics of the assay are consistent with the release in the first 5 s of 0.6 nmol mg of protein−1. The final extent of Ca2+-dependent release amounts to 1.9 nmol mg of protein−1, or 8.5% of the total intrasynaptosomal glutamate content. Preincubation of synaptosomes at 30°C for 2 h before depolarization leads to a decrease in Ca2+-independent release and an increase in Ca2+-dependent release, consistent with an intrasynaptosomal relocation of the amino acid.
461 citations
TL;DR: A longitudinal study conducted to examine the effects of the transition to university in residential and home-based students found that the gain in psychological disturbance following the transition was greater for the homesick group.
Abstract: A longitudinal study was conducted to examine the effects of the transition to university in residential and home-based students. All students showed evidence of raised psychological disturbance and absent-mindedness following the transition. Although there were no differences between resident and home-based students in this respect, those who reported homesickness were distinguished from the remainder in terms of higher levels of psychological disturbance and cognitive failure following the transition to university. Covariate analysis established that the gain in psychological disturbance following the transition was greater for the homesick group. The results are discussed in terms of the effects of stressful transitions on psychological state and the concept of personal vulnerability.
375 citations
TL;DR: It is demonstrated that REP-stabilized mRNA can be translated in vivo and that cloning the REP sequence downstream of a gene can increase protein synthesis, providing direct evidence that alterations in mRNA stability can play a role in determining bacterial gene expression.
340 citations
TL;DR: Control of the size of the intramuscular free pool of glutamine may be important in determining the muscle protein mass as well as the rate of muscle protein synthesis in the presence or absence of insulin.
270 citations
TL;DR: A detailed comparison of the Opp components with those of other binding protein-dependent transport systems provides insight into the mechanisms and evolution of these transport systems.
262 citations
TL;DR: The results suggest that certain naturally occurring steroids potentiate the actions of GABA and, additionally, directly activate the GABAA receptor.
Abstract: The naturally occurring progesterone metabolites 5β-pregnan-3α-ol-20- one and 5β-pregnane-3, 20-dione reversibly enhance membrane currents elicited by locally applied GABA in bovine adrenomedullary chromaffin cells. Such potentiation was not influenced by the benzodiazepine antagonist Ro 15-1788. At concentrations in excess of those necessary to evoke potentiation of GABA currents, 5β-pregnan-3α-ol-20-one and 5β-pregane-3, 20-dione directly activated a membrane conductance. The resulting currents were potentiated by phenobarbitone and diazepam, and abolished by the GABA A -receptor antagonist, bicuculline. On outside-out membrane patches, 5β-pregnan-3a-ol-20-one and 5β-pregnane-3, 20-dione activated single channel currents of similar amplitude to those evoked by GABA. The results suggest that certain naturally occurring steroids potentiate the actions of GABA and, additionally, directly activate the GABA A receptor.
251 citations
TL;DR: A role for mRNA stability in controlling relative gene expression within a polycistronic operon is demonstrated and a single REP sequence seems to be as efficient as the two normally found in this intergenic region at stabilizing translationally active upstream mRNA.
234 citations
TL;DR: Copper adsorption by Rhizopus arrhizus, Cladosporium resinae and Penicillium italicum was studied using a copper-selective electrode.
Abstract: Copper adsorption by Rhizopus arrhizus, Cladosporium resinae and Penicillium italicum was studied using a copper-selective electrode. Copper adsorption by C. resinae and P. italicum obeyed the Freundlich and Langmuir isotherms for single-layer adsorption whereas R. arrhizus followed the BET isotherm for multi-layer adsorption. Temperature had little effect on adsorption over the range 4–25°C. Mineral acids were effective for desorption of copper from preloaded biomass, the efficiency of desorption increasing with decreasing pH. Other cations were also capable of copper desorption with zinc showing the greatest efficiency and sodium the lowest.
233 citations
TL;DR: Quadriceps muscle protein turnover was assessed in the post-absorptive state in six men immediately after the end of unilateral leg immobilization in a plaster cast after tibial fracture andobilization was associated with a significant atrophy of type I muscle fibres.
Abstract: Quadriceps muscle protein turnover was assessed in the post-absorptive state in six men immediately after the end of unilateral leg immobilization (37 +/- 4 days) in a plaster cast after tibial fracture. A primed-constant intravenous infusion of L-[1-13C]leucine was administered over 7 h. Quadriceps needle biopsies, taken bilaterally at the end of the infusion, were analysed for muscle protein leucine enrichment with 13C. Quadriceps muscle protein synthetic rate, calculated from the fractional incorporation of [13C]leucine into protein compared with the average enrichment of blood alpha-ketoisocaproate, was 0.046 +/- 0.012%/h in the uninjured leg, but was only 0.034 +/- 0.007%/h in the quadriceps of the previously fractured leg (P less than 0.05, means +/- SD). Muscle RNA activity (i.e. protein synthetic rate per RNA) fell from 0.27 +/- 0.08 microgram of protein synthesized h-1 microgram-1 of RNA in the control leg to 0.14 +/- 0.03 microgram of protein synthesized h-1 microgram-1 of RNA in the immobilized leg (P less than 0.02). Immobilization was associated with a significant atrophy of type I muscle fibres (mean diameter 69.5 +/- 21 microns immobilized, 81.1 +/- 18 microns control, P less than 0.05), but no significant change occurred in type II fibre diameter. Mean quadriceps fibre volume calculated from the values for fibre diameter and percentage of each fibre type, was smaller in the injured leg by 10.6%; this value was near to the calculated difference in muscle thigh volume (calculated from thigh circumference and skin-fold thickness) which was less by 8.3%.(ABSTRACT TRUNCATED AT 250 WORDS)
224 citations
TL;DR: The number of Golgi apparatus in both interphase and mitotic HeLa cells was found to increase substantially during mitosis to the point where random partitioning alone would explain the nearly equal numbers found in each daughter cell.
Abstract: Osmium impregnation was used to determine the number of Golgi apparatus in both interphase and mitotic HeLa cells. The number was found to increase substantially during mitosis to the point where random partitioning alone would explain the nearly equal numbers found in each daughter cell.
TL;DR: High levels of intracellular trehalose in stationary-phase cells of Saccharomyces cerevisiae or cells incubated in the absence of a nitrogen source were found to increase the resistance of the cells to dehydration, and it appeared that a minimum internal concentration of 120 mM tre Halose was required before there was a significant increase in dehydration resistance.
Abstract: High levels of intracellular trehalose in stationary-phase cells of Saccharomyces cerevisiae or cells incubated in the absence of a nitrogen source were found to increase the resistance of the cells to dehydration. Exponential-phase cells showed negligible dehydration resistance. When stationary-phase cells were inoculated into fresh medium, trehalose was rapidly broken down, and this was correlated with a rapid loss of dehydration resistance. It appeared that a minimum internal concentration of 120 mM trehalose was required before there was a significant increase in dehydration resistance. Exogenous trehalose increased the dehydration resistance of S. cerevisiae: this effect was most marked for stationary-phase cells, where almost 100% survival was obtained at trehalose concentrations of 500 mM and above while maximum survival for exponential cells was less than 10%, even at 1000 mM external trehalose.
TL;DR: Transcription of the genes encoding the high-affinity potassium and betaine transport systems of E.coli and Salmonella typhimurium is tightly regulated in response to osmotic stress, and cytoplasmic ionic strength plays an important regulatory role.
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TL;DR: There are potentially beneficial effects of vacuolation (dependent on specific vacuolar contents) on the acquisition of resources, and on the storage, manipulation and protection of resources which have already been acquired.
Abstract: SUMMARY
Many plant cells are characterized by the presence of a vacuole (hypertrophied lysosome) occupying a large fraction of the protoplast. The possible benefits of the presence of the vacuole can be divided into those which are related merely to the increased volume of the protoplast, independent of the nature of the vacuolar contents, and those which depend on the nature of the solutes in the vacuole.
Increasing the volume of the protoplast per unit volume of cytoplasm increases the total surface area of the cell per unit of cytoplasmic volume. This area amplification has potential benefits in terms of resource acquisition under resource-limiting conditions. At a given chromophore concentration in the cytoplasm, dispersal of a given volume of cytoplasm at the periphery of a vacuole increases the efficiency of photon absorption of an ‘average’ chromophore molecule relative to a comparable non-vacuolate cell, unless the chromophore concentration is low arid/or the cell is very small (no package effect) or the total chromophore per unit projected area is such that almost all light is absorbed, regardless of vacuolation. The area amplification also increases the plasmalemma area per unit cytoplasmic volume through which‘lipid solution’, or mediated transport of chemical resources can occur on a cytoplasmic volume basis and decreases the impediment to resource transfer from a bulk aqueous phase to the cell surface, again on a cytoplasmic volume basis. The increased capacity for uptake of chemical resources from low external concentrations due to vacuolation can increase overall solute acquisition, except in cells of picoplankton size, although other remedies for restricted capacity for chemical nutrient uptake per unit cytoplasmic volume are possible (e.g. evaginations of the cell surface).
In addition to these potential benefits of vacuolation which are essentially independent of the contents of the vacuole, and which relate almost entirely to the rate at which resources can be acquired, there are potentially beneficial effects of vacuolation (dependent on specific vacuolar contents) on the acquisition of resources, and on the storage, manipulation and protection of resources which have already been acquired. Effects of vacuolation which involve essentially irreversible deposition (within the life of the cell) of specific solutes in the vacuole embrace the acquisition, manipulation and protection of resources, but not, of course, true (‘reversible’) storage. Deposition-related increases in resource (at least phosphate and iron) acquisition capacity can, in attached rhizophytic macrophytes, result from rhizosphere acidification involving accumulation of cation salts of organic acid anions in the vacuole. Related to resource acquisition (CO2, H2O) in terrestrial halophytes is the disposal of ‘excess’ salt entering the roots by deposition in hypertrophied vacuoles. Resource manipulation involving deposition of salts of organic acid anions occurs as a means of OH− disposal in the reduction of NO3− in the shoot, a process which can increase the photon and water use efficiency of N assimilation. Resource protection in plants often involves the deposition of antibiophage solutes in the vacuoles. The possible osmotic problems engendered by cation organate deposition can be ameliorated by production of insoluble calcium oxalate.
Reversible accumulation of solutes in vacuoles is involved in CAM, which can increase the water (and nitrogen?) use efficiency of carbon assimilation, and may be involved in the storage of fermentation products during temporary anoxia. The storage of soluble compounds in vacuoles during CAM cannot, apparently, be replaced by that of insoluble materia; there is some scope for storage of insoluble waxes during fermentation. Storage of energy and carbon (as reduced carbon), phosphorus and nitrogen often involves soluble low-molecular weight materials in large vacuoles, but can also, in all three cases, involve polymers in smaller vacuoles or in other parts of the cytoplasm.
Other potentially beneficial effects of vacuolation include a (mechanistically unexplained) stimulation of the velocity of cytoplasmic streaming in large vacuolate cells and a role in buffering cytoplasmic volume from rapid, large changes in cells (e.g. stomata) undergoing large changes in protoplast volume.
Against these putative benefits must be set, in terms of natural selection, the costs of vacuolation. These costs include the costs (energy, solutes) of producing, and those (energy) of maintaining the vacuoles, and the costs (energy, carbon) of synthesizing the extra wall material. The additional costs (all on a unit cytoplasm basis) can be substantial relative to benefits in terms of additional energy and carbon acquisition resulting from vacuolation. Additional costs may be incurred in relation to the energetics of large cells maintaining a constant turgor pressure in environments (e.g. estuaries) with frequent and large changes in external osmolarity, and as colonization opportunities lost if vacuolation reduces desiccation tolerance.
The analysis conducted in the paper suggests that the specific growth rate of a cell of a given cytoplasmic volume under optimal growth conditions is decreased if it is vacuolated. Furthermore, the resource acquisition rate of the cell under conditions of low resource availability may be enhanced by vacuolation, even when the resource costs of vacuolation are taken into consideration, although this is not invariably so. Nevertheless, although the cost-benefit analysis of resource acquisition may not always favour vacuolation, the presence of vacuoles may still lead to an increase in inclusive fitness when benefits in relation to the storage, manipulation and protection of resources are also considered. At all events, most phototrophs are vacuolate, the major exception being many planktophytes (where the lack of vacuoles may be rationalized, at least for smaller cells) and essentially all microalga-invertebrate synthesis.
TL;DR: It is suggested that exocytosis is triggered by the penetration ofCa2+ into an intracellular hydrophobic milieu and that ionomycin is able to bypass this block and deliver Ca2+ to theExocytotic apparatus.
Abstract: The exocytotic release of L-glutamate from guinea-pig cerebral cortical synaptosomes can be extensively inhibited by preincubation with botulinum neurotoxin type A at 37 degrees C for 1-2 h. The toxin has no effect on synaptosomal respiratory control, respiratory capacity, ATP synthesis, plasma-membrane 86Rb+ permeability or plasma-membrane potential, does not inhibit the entry of 45Ca2+ into the synaptosome upon depolarization and does not alter the ability of intrasynaptosomal mitochondria to sequester Ca2+. The blockade of Ca2+-dependent glutamate release may be totally reversed by the Ca2+/2 H+-exchange ionophore ionomycin, but not by increasing extracellular Ca2+ concentration. It is suggested (a) that exocytosis is triggered by the penetration of Ca2+ into an intracellular hydrophobic milieu; (b) that this stage is blocked by the toxin and (c) that ionomycin is able to bypass this block and deliver Ca2+ to the exocytotic apparatus.
TL;DR: Determinations of intracellular glycerol levels with respect to cell osmotic volumes showed that increases in intraceocytes may counterbalance up to 95% of the external osmotically significant pressure due to added NaCl.
Abstract: Natural-abundance 13C-nuclear magnetic resonance spectroscopy has shown glycerol to be the major osmotically significant low-molecular-weight solute in exponentially growing, salt-stressed cells of the yeasts Saccharomyces cerevisiae, Zygosaccharomyces rouxii, and Debaromyces hansenii. Measurement of the intracellular nonosmotic volume (i.e., the fraction of the cell that is osmotically unresponsive) by using the Boyle-van't Hoff relationship (for nonturgid cells, the osmotic volume is directly proportional to the reciprocal of the external osmotic pressure) showed that the nonosmotic volume represented up to 53% of the total cell volume; the highest values were recorded in media with maximum added NaCl. Determinations of intracellular glycerol levels with respect to cell osmotic volumes showed that increases in intracellular glycerol may counterbalance up to 95% of the external osmotic pressure due to added NaCl. The lack of other organic osmotica in 13C-nuclear magnetic resonance spectra indicates that inorganic ions may constitute the remaining component of intracellular osmotic pressure.
TL;DR: A continuous enzyme‐linked fluorometric assay was used for determining the characteristics for glutamate exocytosis from guinea‐pig cerebrocortical synaptosomes and found that the protonophore carbonylcy‐anide p‐trifluoromethoxyphenylhydrazone causes a time‐dependent loss of exocyTosis that is oligomycin insensitive and may be due to depletion of vesicular glutamate.
Abstract: A continuous enzyme-linked fluorometric assay was used for determining the characteristics for glutamate exocytosis from guinea-pig cerebrocortical synaptosomes. Ca2+-dependent release can be induced not only by K+, but also by the Na+ channel activator veratridine and the Ca2+ ionophore ionomycin. K+-induced release can be inhibited by the Ca2+ channel inhibitor verapamil. Sr2+ and Ba2+ substitute for Ca2+ in promoting K+-induced release. Agents that would be predicted to transform the transvesicular pH gradient into a membrane potential are without effect on glutamate release. However, the protonophore carbonylcy-anide p-trifluoromethoxyphenylhydrazone causes a time-dependent loss of exocytosis that is oligomycin insensitive and may be due to depletion of vesicular glutamate. The Ca2+-independent release of glutamate from the cytosol on depolarization is unchanged or promoted by metabolic inhibitors that lower the ATP/ADP ratio. In contrast, Ca2+-dependent release is ATP dependent and is blocked by the combined inhibition of oxidative phosphorylation and glycolysis.
TL;DR: The location of the serine residue in the alpha subunit of eIF-2 is reported, which is phosphorylated by both the haem-controlled repressor and the double-stranded RNA-activated inhibitor.
Abstract: Eukaryotic protein synthesis initiation factor 2 (eIF-2) can be phosphorylated on its alpha subunit by two well-characterised protein kinases, termed the haem-controlled repressor (HCR) and the double-stranded RNA-activated inhibitor (dsI). Phosphorylation of eIF-2 by these kinases is thought to be important in the regulation of peptide-chain initiation. We report the location of the serine residue in the alpha subunit, which is phosphorylated by both these enzymes. Limited tryptic digestion and subsequent cyanogen bromide treatment of rat liver eIF-2 phosphorylated by HCR yielded one major phosphopeptide. This peptide had the sequence Ile-Leu-Leu-Ser-Glu-Leu-Ser(P)-Arg-Arg. The same major phosphopeptide was obtained from rabbit reticulocyte eIF-2 phosphorylated by HCR or dsI as judged by its behaviour on two-dimensional mapping and reverse-phase chromatography. In all cases the phosphorylated residue was found to be serine-7, and not serine-4, of the above sequence as determined from sequence analysis and by subdigestion of the peptide with Staphylococcus aureus V8 proteinase.
TL;DR: This study has shown that there was a significant exposure of the distal esophagus to acid and that the normal acid clearance of the esophagi in the supine position was impaired after only moderate amounts of alcohol.
Abstract: The effect of 120 mL (4 oz) of scotch whiskey (40% alcohol) on nocturnal gastroesophageal reflux was studied by ambulatory esophageal pH monitoring. Seventeen healthy volunteers were studied on two occasions, using a computerized radiotelemetric esophageal pH monitoring system. The subjects were given the alcohol during the second session, three hours after the evening meal, and went to bed at their usual time. Seven of the 17 subjects had prolonged supine reflux episodes on the night of alcohol ingestion. These lasted an average of 47.1 minutes (23.2 to 91.8 minutes) and occurred on an average of 31/2 hours after ingestion of whiskey and 1.4 hours after lying down. None of the subjects had these episodes on the control night. There was also a significant acidic shift in the cumulative percentage of data points below a pH of 3 and a pH of 4 in the supine position on the night of alcohol ingestion compared with the control night. This study has shown that there was a significant exposure of the distal esophagus to acid and that the normal acid clearance of the esophagus in the supine position was impaired after only moderate amounts of alcohol. ( JAMA 1987;258:2077-2079)
TL;DR: A 1.5 kb clone containing the full‐length coding sequence of a type‐1 protein phosphatase catalytic subunit has been isolated from a rabbit skeletal muscle cDNA library constructed in λgt10.
TL;DR: The kinetic characteristics of system Nm are such that glutamine is likely to be the most rapidly exchanging amino acid across the muscle membrane at physiological intra‐ and extracellular glutamine concentrations.
Abstract: 1. We have investigated glutamine transport in the perfused rat hindlimb using the paired-tracer isotope dilution technique. 2. Uptake of L-glutamine was stereospecific, saturable, sodium dependent, insulin sensitive and pH insensitive in the physiological range. The maximum capacity of transport (Vmax) under normal perfusate conditions at 37 degrees C, 145 mM-Na+ and in the absence of insulin was 1156 +/- 193 nmol min-1 g-1 with transport being half-maximal at a perfusate glutamine concentration of 9.25 +/- 1.15 mM. 3. The kinetics of Na+ dependence strongly suggested co-transport of Na+ and glutamine with a stoichiometry of 1:1; furthermore, Na+ activated the carrier without any change in the concentration of glutamine at which transport was half-maximal, i.e. a 'Vmax effect' rather than a 'Km effect'. 4. The characteristics of glutamine transport, especially its substrate specificity and the pattern of competitive and non-competitive inhibition of glutamine transport by other amino acids, suggest that it is mediated by a carrier or carriers for which asparagine and histidine are also suitable substrates. 5. The characteristics of muscle glutamine transport are related but distinct from those of system N identified in hepatocytes; we suggest that they are sufficiently distinct to justify the identification of a new variant of mammalian amino acid transport systems which may be identified by the symbol Nm. 6. The kinetic characteristics of system Nm are such that glutamine is likely to be the most rapidly exchanging amino acid across the muscle membrane at physiological intra- and extracellular glutamine concentrations. Its hormone and ion sensitivities are likely to be important in the physiological modulation of whole-body glutamine metabolism and also during derangements observed in disease and after injury.
TL;DR: It is concluded that a short-term reversible effect of NO−3 may act via an increased resistance to O2 diffusion in nodules; this is coupled to decreased bacteroid respiration.
Abstract: Published data on, and hypotheses regarding the effect of NO−3 on functioning of legume root nodules are reviewed. It is concluded that a short-term reversible effect of NO−3 may act via an increased resistance to O2 diffusion in nodules; this is coupled to decreased bacteroid respiration. For longer exposures to NO−3 nodule activity is irreversibly lost, but how this relates to carbohydrate deprivation or NO-2 accumulation is unclear. Complicating factors include denitrification reactions and the interaction of NO−2 with leghaemoglobin.
TL;DR: In this paper, short term and long term toxicity data for a variety of fish species are presented, and they show that fish with high chloride uptake rates are more susceptible than those with low chloride uptake rate.
Abstract: Nitrite occurs naturally in fresh waters as a result of nitrification of ammonia and denitrification of nitrate, and its concentration can be enhanced by partial oxidation of ammoniacal discharges. Nitrite is toxic to vertebrates including fish and a principal effect is the conversion of haemoglobin to methaemoglobin which is incapable of oxygen transport although there are circulatory and tissue effects as well. The toxic species is the nitrite ion (NO2) which is believed to enter the blood via the branchial chloride/bicarbonate exchange and fish such as salmonids with high chloride uptake rates are more susceptible than those with low chloride uptake rates, for example carp. Nitrite toxicity is strongly aleviated by chloride and the concentration ratio of these ions is of great importance in assessing toxicity. Short term and long term toxicity data for a variety of fish species are presented. There are no field data on fish populations in waters where nitrite was the only pollutant. However ex...
TL;DR: The results are consistent with a predominant role of the malate-aspartate shuttle in the reoxidation of cytosolic NADH in isolated nerve terminals, and the inhibitor induces a functional 'hypoglycaemia' in nerve terminals and should be used with caution.
TL;DR: The 38-kDa subunit of glycogen synthase from rabbit skeletal muscle was glycogenin, the protein that is bound covalently to glycogen and believed to be the 'primer' involved in the initiation of de novo glycogen synthesis.
Abstract: Glycogen synthase from rabbit skeletal muscle has been shown to be a complex of two types of subunit which have apparent molecular masses of 86 kDa and 38 kDa and are present in a 1:1 molar ratio. The 38-kDa component was separated from the 86-kDa catalytic subunit by gel filtration in the presence of 2 M LiBr, and a number of chymotryptic peptides were sequenced. This demonstrated that the 38-kDa subunit was glycogenin, the protein that is bound covalently to glycogen and believed to be the 'primer' involved in the initiation of de novo glycogen synthesis.
TL;DR: A reduction in the number of character inputs necessary to enter any given text of over 50% is possible when using PAL, giving the user a considerable saving in time and effort.
Abstract: This paper describes a communication aid and keyboard emulator which has been developed at Dundee University. The device, Predictive Adaptive Lexicon (PAL), exploits the redundancy in natural language to reduce the key pushes or character selections necessary during the composition of text. Word predictions are offered to the user from a dictionary, and if one of these is selected the word is completed by PAL. PAL adapts to the user's vocabulary by automatically capturing words which are not already in the dictionary. These will thereafter be offered in prediction lists. A reduction in the number of character inputs necessary to enter any given text of over 50% is possible when using PAL, giving the user a considerable saving in time and effort.
TL;DR: Some alterations in endocrine function were detected prior to the cessation of menstrual periods and there were changes in prolactin, cortisol, TSH and triiodothyronine in relation to menopausal status as well as in ovarian steroids and gonadotrophins.
TL;DR: Tc cell recognition of NP peptide 147–161 is entirely dictated by expression of Kd and not by other B10 or OH background genes of congenic mice, suggesting that antigen and class I MHC interact for Tc recognition.
Abstract: Influenza nucleoprotein (NP) is an important target antigen for influenza A virus cross-reactive cytotoxic T cells (Tc). Here we examine the NP epitope recognized by cloned and polyclonal BALB/c Tc and the genetics of this recognition pattern. We can define NP residues 147–161 as the epitope seen in conjunction with Kd, the only H-2d class I responder allele for NP restriction. H-2d/H-2bF1 mice (C57BL × DBA/2) primed by influenza infection lyse only H-2d target cells treated with peptide 147–161 while H-2b targets are recognized only after treatment with NP residues 365–379 (previously found to be recognized by Db restricted Tc cells). Tc cell recognition of NP peptide 147–161 is entirely dictated by expression of Kdand not by other B10 or OH background genes of congenic mice. Restriction of a unique NP sequence by each responder class I major histocompatibility complex (MHC) allele suggests that antigen and class I MHC interact for Tc recognition.
TL;DR: A 'foetal' form of UDP-glucuronyltransferase may exist in human liver that is more restricted in substrate specificity than are those of the rat or rhesus monkey.
Abstract: UDP-glucuronyltransferase activities towards eight substrates were assayed in samples of foetal, term and adult human liver. Activities towards bilirubin, androsterone, testosterone, 1-naphthol, 4-nitrophenol and 2-aminophenol were present in foetal and term liver samples at less than 14% of adult values, whereas activity towards 5-hydroxytryptamine was present in foetal and term liver at 109 and 121% of adult values respectively. Thus a 'foetal' form of UDP-glucuronyltransferase may exist in human liver that is more restricted in substrate specificity than are those of the rat or rhesus monkey.