Characterization of a meta-Fluorotyrosine-Tolerant Cell Culture of Eschscholtzia californica Cham

A cell line of Eschscholtzia californica selected for meta-fluorotyrosine (MFT) tolerance was found to have 10-fold increased levels of phenylalanine and tyrosine compared to the parent line, while most other amino acids were only increased 2-fold. Tracer experiments with shikimic acid in the presence of MFT showed that the biosynthesis of the aromatic amino acids was not impaired in the tolerant line. Feeding experiments with phenylalanine, tyrosine, or shikimic acid also revealed a reduced turnover of the pools of the aromatic amino acids in the variant. Thus undisturbed de novo biosynthesis of the aromatic amino acids and dilution of toxic effects of MFT by the enlarged pool sizes seemed to be the main reason for the acquired tolerance. Despite the enlarged availability of the precursor tyrosine, formation of the benzophenanthridine alkaloids was enhanced neither in the growth nor in the production medium.     

Development ofBradyrhizobium infections in supernodulating and non-nodulating mutants of soybean (Glycine max [L.] Merrill)

Summary The early events in the development of nodules induced byBradyrhizobium japonicum were studied in serial sections of a wild type (cv. Bragg), a supernodulating mutant (nts 382) and four non-nodulating mutants (nod49, nod139, nod772, andrj ₁) of soybean (Glycine max [L.] Merrill). Cultivar Bragg responded to inoculation in a similar manner to that described previously for cv. Williams; centres of sub-epidermal cell divisions were observed both with and without associated infection threads and most infection events were blocked before the formation of a nodule meristem. The non-nodulating mutants (nod49, nod772, andrj ₁) had, at most, a few centres of sub-epidermal cell divisions. In general, these were devoid of infection threads and did not develop beyond the very early stages of nodule ontogeny. Sub-epidermal cell divisions or infection threads were never observed on mutant nodl39. This mutant is not allelic to the other non-nodulating mutants and represents a defect in a separate complementation group or gene that is required for nodulation. The supernodulating mutant nts382, which is defective in autoregulation of nodulation, had a similar number of sub-epidermal cell divisions as the wild-type Bragg, but a much greater proportion of these developed to an advanced stage of nodule ontogeny. Mutant nts382, like Bragg, possessed other infection events that were arrested at an early stage of development. The results are discussed in the context of the progression of events in nodule formation and autoregulation of nodulation in soybean.Abbreviations nts nitrate tolerant symbiosis - RT root tip (i.e., position of the tap root tip at the time of inoculation) - SERH shortest emerging root hair (i.e., position of the shortest emerging root hair on the tap root at the time of inoculation) - SCD subepidermal cell divisions     

Gastric emptying and serum insulin levels after intake of glucose-polymer solutions

To examine the gastric emptying characteristics of four drinks varying in carbohydrate composition and concentration, five men ingested 600 ml of one of the different drinks on four separate occasions. All drinks contained Na+ 71 mmol.l-1, Cl- 60 mmol.l-1, Mg+2 5 mmol.l-1 and citrate 7 mmol.l-1; the carbohydrate component was either 3% glucose, 3% glucose-polymer (GP), 5% GP or 10% GP. With 99mTc-diethylene-triaminepenta-acetic acid (DTPA) as a marker, a scintillation camera and computer were used to measure the rate of gastric emptying. The half-emptying times (T 1/2) were inversely related to the glucose content of the solutions. The T 1/2 for 3% PG was 22.4 +/- 4.4 min (mean +/- SE) and for 10% GP 50 +/- 3.3 min (p less than 0.005). There was no significant difference in T 1/2 between the 3% glucose and 3% GP solutions. The increments in blood glucose (highest blood levels from 7.4 +/- 0.3 mmol.l-1 to 8.9 +/- 0.8 mmol.l-1), serum insulin (from 28 +/- 6 mU.l-1 to 77 +/- 13 mU.l-1) and C-peptide (from 3.6 +/- 0.4 micrograms.l-1 to 5.8 +/- 0.9 micrograms.l-1) were related to the amount of carbohydrate ingested. In all cases the serum insulin levels were high enough to inhibit the liberation of free fatty acids from the adipose tissue. It is concluded that the amount of carbohydrate in glucosyl units in the solution is a major determinant of gastric emptying.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of low- and high-density lipoprotein cholesterol on steroid hormone production and ACTH-induced differentiation of rat adrenocortical cells in primary culture

Summary The choroid plexus consists of the choroidal epithelium, a derivative of the neural tube, and the choroidal stroma, which originates from the embryonic head mesenchyme. This study deals with epithelio-mesenchymal interactions of these two components leading to the formation of the organ. Grafting experiments of the prospective components have been performed using the quail-chicken marker technique. Prospective choroidal epithelium of quail embryos, forced to interact with mesenchyme of the body wall of chicken embryos, gives rise to a choroid plexus showing normal morphogenesis and differentiation. The choroidal epithelium induces the differentiation of organtypical fenestrated capillaries, which are highly permeable to intravenously injected horseradish peroxidase. The choroidal epithelium of the grafts constitutes a blood-cerebrospinal fluid barrier. On top of the choroidal epithelium, there are epiplexus cells displaying a typical ultrastructure. The experimental results show that these cells do not originate from the transplanted neural epithelium. Prospective choroidal stroma of chicken embryos does not exert a choroid plexus-inducing influence upon a quail embryo's neural epithelium isolated from parts of the brain that normally do not develop a choroid plexus. The experiments show that the choroidal epithelial cells are determined at least three days before the first organ anlage is detectable.This work was supported by the Deutsche Forschungsgemeinschaft (grant Ch 44/7-1)     

Book Review

International Journal of Primatology -     

Investigation into the critical equilibrium humidity,active atmospheric water absorption and water content ofRhipicephalus evertsi mimeticus

The critical equilibrium humidity for fully engorged nymphs ofRhipicephalus evertsi mimeticus was shown to be between 91% and 93.5% r.h., and for adult male and female ticks to be between 82% and 84.5% r.h. Studies on gnathosoma and idiosoma by selective exposure to differing relative humidities have shown that dehydrated adult male and female ticks are capable of active uptake of atmospheric water vapor only through their mouthparts. The percentage of water content of unfed adult male and female ticks previously dehydrated was not influenced by subsequent exposure to different relative humidities, varying similarly in both sexes, male imagines between 59.6% and 63.7%, female imagines between 59.6% and 64.4%. Analogous values (62.3% and 61.1%) were obtained for the water content of male and female imagines not previously dehydrated, which were incubated at 30°C and 100% r.h. for 7 days.     

Characterisation of neuropeptides of the AKH/RPCH-family from corpora cardiaca of Coleoptera

Summary Extracts of corpora cardiaca from two members of the family Tenebrionidae,Zophobas rugipes andTenebrio molitor, from one member of the Chrysomelidae,Leptinotarsa decemlineata, and from three members of the Scarabaeidae,Pachnoda marginata, P. sinuata andMelolontha hippocastani, were assayed for adipokinetic and hypertrehalosaemic activity in acceptor locusts (Locusta migratoria) and cockroaches (Periplaneta americana), respectively. All corpus cardiacum material tested, except that from the cockchafer,M. hippocastani, gave positive bioassay results. Biological activities of corpus cardiacum extracts from all species investigated can be resolved on reversed-phase high performance liquid chromatography (RP-HPLC). Gland extracts from the two tenebrionid species each show a single peak of biological activity associated with a single peak of UV absorbance having an identical retention time in both species. The two biologically active fractions from the corpora cardiaca of the potato beetle,L. decemlineata, coelute with exogenous (synthetic) hypertrehalosaemic hormones I and II of the American cockroach. The two species of the genusPachnoda contain two active compounds in their glands; compound I of each species is more abundant and elutes just ahead of the (synthetic) hypertrehalosaemic hormone of the cockroachBlaberus discoidalis. The gland material ofM. hippocastani exhibits and absorbance peak with the same retention time as the major peak from thePachnoda-species; however, this peak material does not elicit biological activity in the assays used here. After fractionation by RP-HPLC the main biologically active compounds were subjected to amino acid analyses. All factors are peptidic and contain 8 amino acid residues. The peptides from the tenebrionid species have the amino acid residues Asx₍₂₎, Glx₍₁₎, Ser₍₁₎, Pro₍₁₎, Leu₍₁₎, Phe₍₁₎ and Trp_(i), whereas the main peptide from corpora cardiaca ofP. marginata contains the residues Asx₍₂₎, Glx₍₁₎, Ser₍₁₎, Pro₍₁₎, Tyr₍₁₎, Leu₍₁₎ and Trp₍₁₎. Amino acid composition analyses of the two active fractions fromL. decemlineata reveal the residues Asx₍₂₎, Glx₍₁₎, Ser₍₁₎, Pro₍₁₎, Val₍₁₎, Phe₍₁₎ and Trp₍₁₎ for compound I and Asx₍₁₎, Glx₍₁₎, Thr₍₂₎, Pro₍₁₎, Leu₍₁₎, Phe₍₁₎ and Trp₍₁₎ for compound II.     

Effects of various alcoholic supplements on the growth rate of Clostridium acetobutylicum ATCC 824

Summary The inhibitory effect of various alkanols, benzyl alcohol and phenethyl alcohol on the growth rate of Clostridium acetobutylicum ATCC 824 was investigated. Inhibition of cell growth was studied by treating cultures with varied concentrations of alcohols. There was a threshold concentration above which growth inhibition occurred. The degree of inhibition was a linear function of the alcohol concentration used. The natural logarithm of the inhibition constant was shown to be: (1) a linear function of the chain length of the alkanols, (2) a linear function of the natural logarithm of the octanol/water partition coefficient for both aliphatic and cyclic alcohols.