Transient gene expression in electroporated banana (Musa spp., cv. ‘Bluggoe’, ABB group) protoplasts isolated from regenerable embryogenetic cell suspensions

Summary Electroporation conditions were established for transient expression of introduced DNA in banana (Musa spp., cv. Bluggoe) protoplasts isolated from regenerable embryogenic cell suspensions. The following parameters were found to be highly influential: electroporation buffer, polyethylene glycol treatment and its duration before electroporation, use of a heat shock, and chimaeric gene constructs. The maximum frequency of DNA introduction as detected by an in situ assay for transient expression of the uidA gene, amounted to 1.8% of total protoplasts. Since plants have recently been regenerated from banana protoplasts at a high frequency, the present results may contribute to the production of transgenic banana.Abbreviations AMV alfalfa mosaic virus - CaMV cauliflower mosaic virus - 2,4-D 2,4-dichlorophenoxyacetic acid - EGTA ethylene glycol-O-O'-bis(2-aminoethyl)-N,N,N',N'-tetraacetic acid - GUS glucuronidase - HEPES 4-(2-nydroxyethyl)piperazine-1-etnanesulfonic acid - MES 2-morpholinoethanesulfonic acid - MS Murashige-Skoog - NOS nopaline synthase - NFTII neomycin phosphotransferase - PEG polyethylene glycol - TGE transient GUS expression - X-Gluc 5-bromo-4-chloro-3-indolyl -D-glucuronic acid     

Comparability and validity of two clinical scores in the early differential diagnosis of acute stroke.

OBJECTIVE--To compare two available clinical scores for the differential diagnosis of cerebral ischaemia and haemorrhage in acute stroke patients. DESIGN--Prospective, multicentre study of acute stroke patients evaluated with computed tomography and Allen and Siriraj scores; the scores were tested for comparability (kappa statistic) and validity (sensitivity, specificity, positive and negative predictive values, diagnostic gain). The effect of a policy of using Allen and Siriraj scores to determine pathological type of stroke before computed tomography was calculated. SETTING--Three hospitals in Italy, all participating in the international stroke trial, with different access facilities to computed tomography. SUBJECTS--231 consecutive patients who were screened in the three hospitals for possible inclusion in the international stroke trial from 1 November 1991 to 31 May 1993. RESULTS--The prevalence of haemorrhage (diagnosed with computed tomography) was 14.7% (95% confidence interval 10.1% to 19.3%). Allen scores were "uncertain" in 44 cases and Siriraj scores in 38 cases; in the 164 cases with both the scores in the range of "certainty" kappa was 0.72. Sensitivity, specificity, positive and negative predictive values, and diagnostic gain for haemorrhage were 0.38, 0.98, 0.71, 0.91, and 0.58 for Allen scores and 0.61, 0.94, 0.63, 0.93, and 0.48 for Siriraj scores; positive predictive values for infarction were 91% for Allen scores and 93% for Siriraj scores. According to these data, of 1000 patients with acute stroke, 680 would be correctly and 70 wrongly diagnosed as "ischaemic" with the Allen score; the figures would be 671 and 48 with Siriraj score. CONCLUSION--When computed tomography is not immediately available and the clinician wishes to start antithrombotic treatment (or randomise patients in a clinical trial), the Siriraj score (and possibly the Allen score) can be useful to identify patients at low risk of intracerebral haemorrhage.     

Preparation of the tritiated molecular forms of gangliosides with homogeneous long chain base composition

Gangliosides G_M2, G_M1 and G_D1b were radiolabelled at C-6 of the terminal galactose orN-acetylgalactosamine by the galactose oxidase/[³H]NaBH₄ method; gangliosides G_M2, G_M1, Fuc-G_M1 and G_D1a were radiolabelled at C-3 of the long chain base by the 2,3-dichloro-5,6-dicyanobenzoquinone/[³H]NaBH₄ method.By application of an original HPLC procedure, eight different molecular species were prepared from each labelled ganglioside. Each of these species was characterized by the presence of one of the following long chain bases:erythro C18 sphingosine,threo C18 sphingosine,erythro C18 sphinganine,threo C18 sphinganine,erythro C20 sphingosine,threo C20 sphingosine,erythro C20 sphinganine andthreo C20 sphinganine.From G_D1b only the species containing theerythro forms of long chain bases were obtained.The individual molecular species were more than 99% homogeneous and had a radiopurity better than 99%. The molecular species of the same ganglioside, radiolabelled at C-3 of the long chain base, had identical specific radioactivity, namely 1.17, 1.25, 0.85 and 1.28 Ci/mmol for G_M2, G_M1, Fuc-G_M1 and G_D1a respectively. The molecular species of the same ganglioside, radiolabelled at C-6 of terminal galactose orN-acetylgalactosamine, had similar specific radioactivity, namely 1.34–1.40, 1.44–1.51, 1.37–1.44 Ci/mmol for G_M2, G_M1 and G_D1b respectively.     

Studies on secretory glycoproteins in the rat exocrine pancreas

Summary A fetuin, fucosyl transferase has been identified in the smooth microsomal fraction from the rat exocrine pancreas. This enzyme is involved in the glycosylation of secretory proteins and is bound to membranes, predominantly of the Golgi complex. Optimal in vitro conditions for the assay of the enzyme activity were established: a pH of 5.5–6.0, a temperature of 21° C and concentrations of Mg^{+ +} at 5.0 mM and ATP at 2.0 mM.Supported by a grant from the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (Ke 113/10). Dedicated to Professor Helmut Ferner, Vienna, on the occasion of his 65^th birthday.     

Immunochemical purification of probe-labeled plasma membrane proteins: An approach to the molecular anatomy of the cell surface

The probe 2,4,6-trinitrobenzene sodium sulfonate may be used under appropriate conditions for selective labelling of plasma membrane proteins exposed at the outer cell surface. Labeled proteins, solubilized by detergents, can be purified by reverse immunoadsorption using antiprobe antibodies covalently linked to Sepharose 4B. This method has been applied to an investigation of the outer cell surface structure of chicken embryo and hamster fibroblasts. Coelectrophoresis in sodium dodecyl sulfate-polyacrylamide gels of probe-labeled membrane proteins purified from baby hamster kidney fibroblasts have shown that 7 major protein groups of different molecular weight are exposed on both control and Rous sarcoma or polyoma virus-transformed cells. Moreover, the transformed cells display a nonvirion component of 80–100 k daltons that is not labeled by the probe in normal cells. In fibroblasts transformed by a temperature sensitive Rous sarcoma virus mutant, that transforms at 37°C but not at 41°C, the expression of this component is related to the expression of the transformed phenotype.     

Oligomycin sensitivity of mitochondrial sulfhydryl groups

Dithionitrobenzoate has been used to titrate sulfhydryl groups of rat liver mitochondria in glutamate buffer, pH 7.4.Reaction with oligomycin and different SH reagents preceded the SH titration. Under these conditions it was found that 2-mercaptopropionylglycine and N-ethylmaleimide reacted in an oligomycin-sensitive manner, so that the control values (in the absence of SH reagent) were obtained.Similar concentrations of mersalyl and of N-(N-acetyl-4-sulfamoylphenyl) maleimide, in the presence of oligomycin, enhanced reactivity toward Nbs₂.The concentration range of oligomycin-sensitive SH groups was thus defined between approx. 5 and 9 nmol reagent/mg mitochondrial protein.In this way, a differentiation between SH groups, which are implicated in phosphate transport and those, which react in an oligomycin-sensitive manner, and which are probably connected with the coupling mechanism, was achieved.     

Delayed cutaneous hypersensitivity reaction to crude and semi-purified tumor extracts in cancer patients

Summary A positive delayed cutaneous hypersensitivity reaction (DCHR) was observed to only one of five KCl soluble extracts from as many different tumoral kidneys in nine of 11 patients with kidney cancer. None of the autologous normal renal tissue extracts gave a positive reaction. SDS-PAGE analysis showed a predominant component with a molecular weight corresponding to that of serum albumin in all the four negative cancer extracts. Lipoproteins and serum albumin were removed by ultracentrifugal flotation on KBr and by affinity chromatography on antiserum albumin (-HSA), respectively, from one of the negative crude extracts. KCl extract, F₂ fraction of KBr, and unbound material from the -HSA column were injected simultaneously into nine patients with renal cancer. Positive DCHRs were seen to the three extracts in no patients, in three, and in eight, respectively. The -HSA unbound fraction was positive in three of 13 patients with tumor at a site other than the kidney. The same extraction procedure was applied to normal autologous kidney tissue, and positive reactivity was observed in one of eight and three of nine patients with kidney cancer to the F₂ and -HSA unbound fractions, respectively. An aliquot of KCl tumor extract was passed through the -HSA column without the preliminary flotation on KBr, and the unbound fraction was positive in eight of nine patients with kidney cancer and in eight of twelve patients with other types of tumor. Three different melanomas were extracted in the same way and an increased percentage of DCHRs was found after removal of lipoproteins and HSA in melanoma patients. This reactivity, however, was not histologically related since patients with tumors other than melanoma reacted as well as melanoma patients. These data indicate that the removal of lipoproteins and HSA from crude tumor extracts may unmask or increase an existing antigenicity. The tumor-type-related experiments, however, suggest that these biochemical procedures are useful for kidney tumors but not for melanomas.     

Electron paramagnetic resonance studies on the fluidity and surface dynamics of egg phosphatidylcholine vesicles containing gangliosides

The influence of different gangliosides (G_M1, G_D1a, G_T1b) on the fluidity and surface dynamics of phosphatidylcholine small unilamellar vesicles was studied by electron paramagnetic resonance. 5-and 16-nitroxystearic acid, sounding respectively the region close to the surface and that close to the hydrophobic core of the vesicle, were employed as spin-label probes. The signals released by 5-nitroxystearic acid showed that the presence of gangliosides reduced the mobility of the hydrocarbon chains around the probe. The effect increased by increasing ganglioside concentration, and diminished from G_M1 to G_D1a and G_T1b. The decrease of membrane fluidity was also monitored by the 16-nitroxystearic acid probe. On addition of Ca²⁺ the fluidity of ganglioside-containing vesicles (as signalled by the 5-nitroxystearic acid probe) promptly decreased, thereafter returning slowly to the original value. It is suggested that gangliosides cause strong side-side head group interactions on the bilayer surface -between ganglioside oligosaccharide chains and between ganglioside and phosphatidylcholine polar portions - which lead the lipid chains to assembly in a more rigid fashion. The influence of Ca²⁺ is interpreted as due to lateral phase separation in the vesicle membrane. This phenomenon can be related to the formation or stabilization of ganglioside clusters on the vesicle surface.     

Haematological studies on Aethotaxis mitopteryx DeWitt,a high-Antarctic fish with a single haemoglobin

Summary The haematological parameters (haematocrit, erythrocyte number, haemoglobin concentration, MCHC, MCH, oxygen-carrying capacity, pH, p_1/2, , pCO₂, pO₂) of the Antarctic fish Aethotaxis mitopteryx DeWitt are reported. The erythrocyte number (0.39 × 10¹²/1) and the haemoglobin concentration (27.8 g/l) were found to be among the lowest values known for red-blooded Antarctic fishes. Among the species of the family Nototheniidae, this is the only one found so far to have a single haemoglobin in its blood. The results have been analysed in comparison with those of other Antarctic species, in an effort to establish correlations between the physiology of this pelagic-benthopelagic fish and its ecology. From the haematological parameters in this study and the functional properties of haemoglobin outlined in the following paper, it is suggested that A. mitopteryx has an extremely sluggish mode of life.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation     

Short and simple synthesis of (R)- and (S)-4-hydroxypentylaminoacetamide: both enantiomers of the (ω-1)-hydroxylated metabolite of milacemide

Both (R)- and (S)-4-hydroxypentylaminoacetamide have been synthesized by reductive amination of glycinamide on the γ-valerolactols corresponding to (R)- and (S)-γ-valerolactone, respectively. These enantiomeric lactones were readily obtained in high enantiomeric excess (ee) by enzymic porcine pancreatic lipase (PPL) kinetic resolution of rac-methyl γ-hydroxyvalerate. © 1992 Wiley-Liss, Inc.