Gonococcal Tonsillar Infections

Neisseria gonorrhoeae were cultured from tonsillar swabs in six men and six women out of 161 consecutive, unselected, Danish patients (95 men and 66 women) suffering from urogenital or rectal gonorrhoea. Gonococci were found in the tonsils in only one out of 49 foreign men with gonorrhoea. Eleven of the Danish patients admitted orogenital contact at their most recent intercourse. The gonococcal complement fixation test was negative in all except two cases. Standard singledose treatment cured the urogenital and rectal infections promptly but failed to cure the tonsillar infection in five cases, and in recalcitrant cases the organisms were demonstrable for some months.     

Callus production from willow (Salix viminalis L.) protoplasts

Protoplasts were isolated from cell suspensions of Salix viminalis (basket willow) clone 78-0-90 and S. schwerinii clone 77-0-77, using cellulysin and macerase in modified Woody Plant medium. For clone 78-0-90, 6.3 · 10⁶ ± 1.9 · 10⁶ protoplasts were obtained per gram fresh weight. Cell divisions started two days after protoplast isolation and gave rise to callus which has been maintained in culture for up to four years. Protoplast yield from the clone 77-0-77 was lower (less than 10⁶ protoplasts per gram cells), cell division was infrequent and no callus was obtained. Protoplasts were also isolated from the leaves of willow shoot cultures using cellulysin and pectolyase, but these did not show cell divisions.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - MS medium Murashige & Skoog (1962) medium - WP medium Woody Plant medium (Lloyd & McCown 1981)     

Factors promoting sustained divisions of mesophyll protoplasts isolated from dihaploid clones of potato (Solanum tuberosum L.) and a cytological analysis of regenerated plants

A culture protocol has been developed for mesophyll protoplasts isolated from various dihaploid clones of potato. A special effort was made to promote the growth of initially dividing cells to form cell colonies and calli. An increase in plating efficiency in 3 different dihaploid clones and one doubled dihaploid clone was obtained after serial dilution of cultures with a suitable amount and type of medium at different stages of cell colony development. Plating on a refined semi-solid medium after 14 days of culture further improved both the yield and the quality of calli obtained. The refined plating medium also enhanced shoot regeneration ability from 67 to 90% in one of the dihaploid clones (67:9). The refined culture protocol could also be used without causing a decrease in plating efficiency at a low population density adjusted after 3 days of culture. The ploidy level of plants regenerated from dihaploid protoplasts were determined by chromosome counting and DNA analysis by flow cytometry. Most of the plants were aneuploid or tetraploid although, some dihaploid plants were obtained after protoplast culture of 2 dihaploid clones derived from the same cultivar (cv. Stina).Abbreviations BA benzyladenine - 2,4-D dichlorophenoxyacetic acid - GA₃ gibberellic acid - NAA naphthaleneacetic acid     

Ibotenic Acid Analogues as Inhibitors of [3H]Glutamic Acid Binding to Cerebellar Membranes

Abstract: The L-[³H]glutamic acid binding capability of rat cerebellar membranes prepared with or without preincubation at 37°C followed by washing was investigated. The two preparations ( K_D = 820 nM, B_max= 54.5 pmol/mg protein; K_D = 509 nM, B_max=13.0 pmol/mg protein) showed no difference in specificity of the binding of the ibotenic acid analogues, consistent with the removal of an endogenous inhibitor by the preincubation at 37°C followed by washing. The order of potency of the ibotenic acid analogues as inhibitors of L-[³H]glutamic acid binding is different from the order of potency in vivo , suggesting that the binding sites found are different from the physiological glutamic acid receptor.     

Alkaloid biosynthesis in somatic hybrids of Duboisia leichhardtii F. Muell. and Nicotiana tabacum L.

Somatic hybrids of Duboisia leichhardtii and Nicotiana tabacum were obtained by electrofusion followed by individual cloning. The hybrid nature of the cloned cells and regenerated shoots was confirmed by cytological investigation and ribosomal-DNA analysis, respectively. The hybrid plantlets predominantly produced nicotine, while Duboisia plantlets produced both tropane and nicotine alkaloids. Activities involved in tropane-alkaloid biosynthesis were examined in a series of precursor-feeding experiments. The presence in the hybrid plants of activities responsible for the reduction of tropinone, the hydroxylation and epoxidation of hyoscyamine, and the conversion of nicotine to nornicotine demonstrated the presence of the Duboisia genes for these enzyme activities.We thank Mr. T. Shikanai, Kyoto University, for the preparation of rice rRNA. We also appreciate Dr. J.H. Fitchen, Kyoto University, for critical discussion and English correction.     

Referate

Ohne Zusammenfassung     

Albumin prevents nonspecific transferrin binding and iron uptake by isolated hepatocytes

Bovine serum albumin inhibits binding of transferrin by hepatocytes in suspension by 60-70%. Iron uptake is inhibited by less than 20%. A Scatchard analysis of the transferrin-binding data reveals a biphasic plot in the absence of bovine serum albumin, but a monophasic plot in the presence of bovine serum albumin. Bovine serum albumin inhibits low-affinity binding of transferrin (125000 molecules/cell), but has no effect on high-affinity binding (38000 molecules/cell). In pronase-treated cells, transferrin binding is reduced by 40%, and when bovine serum albumin is added, the binding is reduced by a further 40%. Corresponding figures for iron uptake are 70 and 10%, respectively. The results are strong evidence that the major part of iron uptake by hepatocytes occurs from transferrin bound to the plasma membrane transferrin receptor.