The haplotype distribution of the ΔF508 mutation in cystic fibrosis families in Scotland

Summary The gene defective in cystic fibrosis (CF) has recently been isolated and the major mutation identified. The haplotype distribution of this mutation (ΔF508) has been determined for 215 CF chromosomes in the Scottish population. ΔF508 represents 73% of all CF mutations in this group. There remains considerable linkage disequilibrium between XV2c and KM19 and other mutations in the CF gene.     

Long-delay learning in rats with parabrachial pontine lesions

Two experiments were conducted to test the hypothesis that ratswith lesions in the parabrachial nucleus of the pons (PbN) canacquire conditioned taste aversions only if the conditionedand unconditioned stimuli are presented close together in time.In experiment 1, rats with lesions in the medial PbN, lateralPbN or outside of the PbN (lesioned control), and unoperatedcontrol rats were trained to avoid Na-saccharin in a one-bottletest. In this procedure, a 5-min delay was imposed between the15-min Na-saccharin presentation and an injection of LiCl (0.3M, 1 % body weight, i.p.). Results showed that, after threeNa-saccharin-LiCl pairings, all rats, except the medial PbNgroup, acquired a strong aversion to Na-saccharin. In experiment2, the same rats were presented with LiCl (0.12 M) in their15-min daily access to fluid on 3 alternate days. Although ratsin the medial PbN group drank more LiCl on day 1 than rats inthe other groups, they significantly reduced their LiCl consumptionon day 2 and did not differ from other groups by day 3. Resultsare discussed in terms of possible behavioral and physiologicalmechanisms that might account for these phenomena.     

Detection of cystathionine and lanthionine ketimines in human urine

A recently developed HPLC procedure for the determination of cystathionine ketimine (CK) and lanthionine ketimine (LK) has been applied to the detection of these compounds in human urine. The assay has taken advantage of the selective production of an absorbance at 380 nm, not seen with other amino acids, when the two ketimines are reacted with phenylisothiocyanate. Coelution with authentic phenylthiohydantoin derivatives of CK and LK and the identical absorption spectra establish the identity of the compounds found in the urine with the synthetic products. Quantitation of the two ketimines by HPLC indicates that the excretion of CK and LK is respectively 606 micrograms and 84 micrograms per g of creatinine as mean values of 10 healthy subjects of both sexes, 20-40 years old, in the early morning voided urine.     

Effects of calcium chelators, divalent cations and sulfhydryl reagents on calcium uptake and motility of bovine spermatozoa

Addition of 1 mM Ca/EGTA complex (1:1 ratio) to an incubation medium containing 1.5 mM Ca2+ produced a notable increase in the Ca2+ cycling in ejaculated bovine spermatozoa. Similar results were also obtained with the Ca/EDTA and Ca/EDTA complexes or with the heavy metal chelator DTPA (50 microM). Ba2+, Ni2+ or Co2+ added at 0.1 mM concentration abolished the stimulatory effect of the Ca/EGTA complex on Ca2+ cycling, whereas it did not affect the calcium movement in the absence of the calcium chelator complex. It is concluded that small amounts of these cations should be bound to the plasma membrane of bovine spermatozoa and inhibit the cellular calcium influx. 0.1 mM Cd2+ and NEM or 1 mM diamide produced a calcium efflux from the spermatozoa together with an inhibition of cellular motility and an increase in glutamate-oxaloacetate transaminase release. Conversely the impermeant sulfhydryl reagent mersalyl caused a net calcium efflux but did not alter the cellular motility nor the transaminase release. It is suggested that the permeant thiol reagents could decrease the spermatozoal mobility by impairing the mitochondrial ATP-synthesis.     

Sodium chloride absorption across the ileal epithelium of the lizardGallotia galloti

Summary Ion transport processes in the ileum of the lizard,Gallotia (=Lacerta) galloti was examined in vitro by measuring Na²² and Cl³⁶ fluxes across short-circuited preparations.In Ringer-bicarbonate solution there was both a net sodium flux ( ) and a net chloride flux ( ) from mucosa to serosa. The inequality between and short-circuit current (I _sc) suggests that part of the net sodium transport is the result of an electrically neutral transport mechanism or that another electrogenic mechanism opposite in sign is contributing to the short-circuit current.In the absence of sodium, the short-circuit current and net chloride flux were abolished. In the absence of chloride, the net sodium was reduced but not abolished and the short-circuit current was unchanged.From an analysis of the effects of the inhibitors furosemide, amiloride, disulfonic stilbene (DIDS) and acetazolamide, a plausible model was developed to explain the characteristics of these transports. It is proposed that the entry of sodium into the cell across the luminal membrane occurs by two pathways. Part occurs by the antiport Na⁺H⁺ and part by an electrogenic pathway. The entry of chloride is by the antiport Cl^–HCO ₃ ^– .Symbols and abbreviations DIDS 4,4 diisothiocyanatostilbene-2,2-disulfonic acid - G _t tissue conductance - I _sc short circuit current - m mucosal - PD potential difference - s serosal     

Genetic engineering strategies for environmental applications.

Environmental applications of genetically engineered microorganisms are currently hampered not only by legal regulations restricting their release, but also by the frequent dearth of adequate genetic tools for their construction in the laboratory. Recent approaches to strain development include the use of non-antibiotic markers as selection determinants, the use of transposon-vectors for the permanent acquisition of recombinant genes, and the utilization of expression devices based on promoters from promiscuous plasmids and biodegradative pathway genes.     

Cellular localization of bovine pancreatic trypsin inhibitor and related molecular forms in bovine lung

Summary In addition to bovine pancreatic trypsin inhibitor (BPTI), three BPTI-related molecular forms (isoinhibitors I, II and III) were isolated from bovine lung by affinity chromatography on immobilized trypsin and subsequently purified by Fast Protein Liquid Chromatography. These inhibitors are identical to the isoinhibitors previously isolated from bovine spleen. Their localization in bovine lung was studied by immunohistochemical techniques, using two different immunoglobulin preparations, selectively recognizing BPTI or the other molecular forms.BPTI-related immunoreactivity was found to be restricted to isolated cells, often identified as mast cells by Toluidine Blue staining. In contrast, isoinhibitor-related immunoreactivity, which also occurs in the mast cells, is present in a number of other cell types. These types include: (i) the smooth muscle cells of different calibre vessels, (ii) the ciliated cells of the bronchial epithelium and the related mucus, and (iii) many cells at alveolar level.Comparison of these data with previous results obtained for bovine spleen suggest multiple physiological roles for these inhibitors.