Time course of osmotic adaptation and gill energetics of rainbow trout (Salmo gairdneri R.) following abrupt changes in external salinity

Summary The physiological and biochemical responses of rainbow trout (mean weight 250 g) to abrupt increases in salinity have been investigated. An initial crisis period lasting about 30 h was characterized by an increase in plasma and muscle ions, a rapid gill dehydration and a pronounced acidosis following a transient alkalosis. Mortality was low during this period. During the following days, gradual changes resulted in new steady state levels for most parameters examined.Analysis of adenylate pool (ATP, ATP/ADP ratio and energy charge) in the gills demonstrated an increased energy demand exhibiting two phases (4 h and 3 days), and a return to freshwater values. The gill respiration rate was constant during 3 days in sea water and decreased slightly later on. It was not influenced during the reverse transfer of seawater adapted fish into fresh water at the level of either isolated gills or perfused heads.     

Location ofMls locus on mouse chromosome 1

Linkage between theMls locus and the chromosome 1 markersDip-1 andald was detected using two sets of recombinant inbred strains. Linkage betweenMls andDip-1 was confirmed in the fifth and sixth backcross generations of an incipient congenic strain. The AKXL data indicate that the gene order isDip-1-ald-Mls. The recombination frequency betweenald andMls is estimated to be 0.07 ±0.05, based on the AKXL data. The recombination frequency betweenDip-1 andMls is estimated to be 0.18 ±0.04, based on all the available data.     

Prospectively randomised trial of proximal gastric vagotomy either with or without pyloroplasty in treatment of uncomplicated duodenal ulcer.

A consecutive series of 100 men with uncomplicated duodenal ulcer was randomly divided into two groups: one group of 52 underwent proximal gastric vagotomy (PGV), the other group (48) underwent PGV with pyloroplasty (PGVP). Preoperative peak acid output (PAOP) was measured in all patients. Those with a higher preoperative PAOP were significantly more likely to develop recurrent ulceration. Three patients developed recurrent ulceration after PGV and seven after PGVP. Dumping was both more common and more severe after PGVP than PGV. An overall satisfactory result was achieved in 92% after PGV and 81% after PGVP. We conclude that combining pyloroplasty with PGV has no appreciable advantages.     

Protein-lipid interactions and differential scanning calorimetric studies of bacteriorhodopsin reconstituted lipid-water systems

Bacteriorhodopsin has been reconstituted at various molar concentrations into liposomes of dimyristoyl- and also of dipalmitoylphosphatidylcholine. Differential scanning calorimetry indicates that as the protein concentration within the lipid bilayer increases, the cooperativity of the lipid phase transition is reduced, i.e. the transition is broadened, while the midpoint transition temperature remains virtually unchanged. Freeze-fracture electron microscopy of our preparation shows, in agreement with previous data from other laboratories, that extensive protein aggregation occurs when the liposome is cooled below the T_c transition temperature of the lipid. Laser flash photolysis measurements of protein rotation of the bacteriorhodopsin show, especially in the case of protein-rich recombinants, that protein aggregates exist even above T_c. The perturbation caused by the presence of bacteriorhodopsin in the lipid bilayer is similar to that produced by other intrinsic proteins. The difficulty of correlating the observed calorimetric enthalpy data with a simple concept of a ‘boundary lipid layer’ based upon consideration of a single isolated protein is discussed in view of the occurrence of protein aggregates both above and below T_c. It is concluded that the reduction of enthalpy is related to the number of lipids which solvate the protein aggregates within the protein-lipid patches and are thereby removed from the cooperative melting and enthalpy of the remaining regions of pure lipid.     

Proteolytic modification of mouse liver catalase

When catalase was immunoprecipitated from different subfractions of mouse liver homogenates, the enzyme which was obtained from extracts of the large granular fraction exhibited a lower molecular weight than that from either the cytosol or purified peroxisomal fractions, as judged by sodium dodecyl sulphate polyacrylamide gel electrophoresis. This modification of the enzyme could be prevented by the addition of proteolytic inhibitors to extraction buffers; and consequently, unmodified catalase was able to be purified in the presence of 5 mM iodoacetamide. Electrophoretic comparison of the catalases against standards of known molecular sizes indicated that the unmodified enzyme had a subunit mass approximately 2,000 daltons larger than the modified enzyme. The significance of these proteolytic modifications has been discussed in relation to the involvements of catalase and peroxisome turnover.     

Synthesis of 4′-methoxyadenosine and related compounds

Addition of iodine and methanol to N⁶,N⁶-dibenzoyl-9(2,3-O-carbonyl-5-deoxy-β-d-erythro-pent-4-enofuranosyl)adenine (4) selectively gives N⁶,N⁶-dibenzoyl-2′,3′-O-carbonyl-5′-deoxy-5′-iodo-4′-methoxyadenosine (5). Compound 5 can be converted into 4′-methoxyadenosine via hydrolysis of the carbonate followed by benzoylation, displacement of the 5′-iodo function by benzoate ion, and hydrolysis with ammonia. Configurational assignments are based upon comparisons of ¹H- and ¹³C-n.m.r. spectra with those of previously characterised analogues in the uracil series and by borate electrophoresis. Intermediates in the above scheme have also been converted into 5′-amino-5′-deoxy-4′-methoxyadenosine, 4′-methoxy-5′-O-sulfamoyladenosine, and ethyl 4′-methoxyadenosine-5′-carboxylate, each of which is a 4′-methoxy analogue of biologically active derivatives of adenosine.     

Fibronectin promotes formation of the close cell-to-substrate contact in cultured cells

The effects of addition of cellular fibronectin on the cell-to-substrate contacts of a non-transformed adhesion-defective mutant, AD6, of the BALB/ c3T3 cell-line, and of transformed L-929 fibroblasts have been examined by interference reflection microscopy (IRM). We report that formation of the close contact, but not focal contacts, is promoted in parallel with an increase in spreading in both cell types. These results provide strong evidence for a functional role of fibronectin in the formation of the adhesive close contact.     

A major stress-inducible Mr-42000 wall glycoprotein of French bean (Phaseolus vulgaris L.)

A major wall protein of suspension-cultured cells of French bean has been isolated and characterised. It can be prepared from walls or the culture filtrate and in composition it is particularly rich in proline, valine and glutamic acid/glutamine and contains appreciable amounts of hydroxyproline. The N-terminus shows some glycosylation, while following chemical deglycosylation the first 38 residues were found to be identical to those of proline-rich proteins from soybean. However, the composition of the highly purified M_r-42000 bean protein differs considerably from the soybean proteins and must contain its own specific domains. An antibody was raised and used to demonstrate the inducibility of the M_r-42000 bean protein in response to elicitor action. The protein was found to be mainly localised in the intercellular spaces of the cortical cells of bean hypocotyls and at the wall-plasmalemma interface of xylem vessels, another potentially accessible compartment for pathogens. Following wounding, the protein was found to be generally distributed in the wall of epidermal and cortical cells of the hypocotyls. The M_r-42000 protein is cross reactive with antibodies raised to glycoproteins of the Rhizobium infection thread and the chitin-binding hydroxyproline-rich glycoprotein, potato lectin. These common epitopes together with the previously demonstrated chitin-binding properties of the bean protein indicate a role in host-microbial interactions. Furthermore, the M_r-42000 protein itself bound to the growing hyphal tips of the bean pathogen, Colletotrichum lindemuthianum.Abbreviations FITC fluorescein isothiocyanate - IgG immunoglobulin G - PAL phenylalanine ammonia-lyase We thank Dr Nick Brewin for advice on interpretation of immunolocalisations and for the gift of MCA 265. We thank Dudley Fernandino for carrying out the confocal microscopy. GPB thanks the Science and Engineering Research Council for funding.