Phosphorus nutrition of barley, buckwheat and rape seedlings. II. Influx and efflux of phosphorous by intact roots of different P status

Seedlings of barley (Hordeum vulgare L. cvs Salka and Zita), buckwheat (Fagopyrum esculentum Moench) and rape (Brassica napus L. ssp. napus cv. Line) were raised at 8 or 10 different extenral P concentrations in the range 0–2000 μM. Apart from P, the nutrient solutions were complete. Phosphate influx in roots of different P status was determined by use of a nutrient solution containing 0.1 mM³²P-labelled phosphate. A double labelling technique was used for simultaneous determination of influx (³³P) and efflux (³²P) of phosphorus by roots of barley and rape with three selected P levels. Flux determinations were also done in presence of a metabolic uncoupler (2,4-dinitrophenol) and a protein synthesis inhibitor (cycloheximide). Influx of phosphate was maximal at a certin optimal P level of the roots and decreased at both lower and higher P levels. Maximum phosphate influex [μmol (g root)-^?1 h^?1] were: rape 4,4, buckwheat 2.2, barley cv. Salka 1.6, barley cv. Zita 1.5. Both Hill plots and plots of the untransformed decreasing phosphate influx vs root P concentrations above the optimal were linear and had high correlation coefficients. The Hill coefficient varied between -3.1 and -4.2. The decrease of phosphate influx from the maximum to the lowest value at the highest P concentration of the root was 60–70%. Hence, phosphate influex appeared to be regulated through negative feedback by the internal level of phosphorous in the roots. The regulation mechanism seems bascially similar for the three species and may be of an allosteric type. P efflux from roots of low and optimal (with regard to P influx) P status was 15–20% of the simultaneous P influx. Contary to P influx, P efflux increased at high P status and almost eliminated (barley) or halved (rape) net P uptake. 2,4-Dinitrophenol reduced both P influx and P efflux by low P roots and gave linearly increasing P efflux with increasing root P status. This indicates that P efflux partly occurred by counter transport and ion exchange at the uptake sites, partly by passive P efflux along an electrochemical potential gradient. Phosphate influx was not affected by inhibition of barley root growth with cycloheximide, but P efflux increased considerably.     

Antagonism of diazepam-induced feeding in rats by antisera to opioid peptides

Diazepam-induced feeding in rats is antagonized not only by the opiate antagonist naloxone but also intraventricular administration of specific antisera to the endogenous opioid peptides met-enkephalin or beta-endorphin. Pituitary beta-endorphin is probably not implicated in the diazepam effect since blockade with the glucocorticoid dexamethasone of the release of beta-endorphin from the anterior pituitary does not modify the diazepam-induced feeding, which is however prevented by TRH, a suggested physiological antagonist of some of the effects of opioid peptides. The possible central participation of both beta-endorphin and met-enkephalin in the ingestive behavior induced by diazepam gives further support to the postulated physiological role of endogenous opioids in appetite regulation.     

A temperature-sensitive mutant of Escherichia coli that shows enhanced misreading of UAG/A and increased efficiency for some tRNA nonsense suppressors

Summary A spontaneous mutant was isolated that harbors a weak suppressing activity towards a UAG mutation, together with an inability to grow at 43° C in rich medium. The mutation is shown to be associated with an increased misreading of UAG at certain codon contexts and UAA. UGA, missense or frameshift mutations do not appear to be misread to a similar extent. The mutation gives an increased efficiency to several amber tRNA suppressors with-out increasing their ambiguity towards UAA. The ochre suppressors SuB and Su5 are stimulated in their reading of both UAG and UAA with preference for UAG. An opal suppressor is not affected. The effect of the mutation on the efficiency of amber and ochre suppressors is dependent on the codon context of the nonsense codon.The mutated gene (uar) has been mapped and found to be recessive both with respect to suppressor-enhancing ability as well as for temperature sensitivity. The phenotype is partly suppressed by the ochre suppressor SuC. It is suggested that uar codes for a protein, which is involved in translational termination at UAG and UAA stop codons.     

Restriction cleavage maps of the DNAs of Streptococcus pneumoniae bacteriophages containing protein covalently bound to their 5'' ends

Summary Several pneumococcal bacteriophages showing a morphology similar to that previously described for Cp-1 (Ronda et al. 1981) have been isolated and purified from throat samples taken from healthy children. Three of these phages (Cp-5, Cp-7 and Cp-9) have been studied in detail and compared to Cp-1. The four phages differed in several respects, e.g. size, structural polypeptides, restriction enzyme cleavage patterns, etc. The DNA of Cp-5, Cp-7 and Cp-9 showed protease-sensitive transfecting activity. This, together with the results obtained by electrophoretic analyses as well as by isotopic labelling of these DNAs with [-³²P] ATP and polynucleotide kinase indicated that all these new phages have a protein covalently linked to the 5 ends of their DNAs as in the case of Cp-1 (García et al. 1983). Restriction enzyme cleavage maps of Cp-1, Cp-5, Cp-7 and Cp-9 have been constructed.     

Polar lipid and isoprenoid quinone composition in the classification of Staphylococcus

Representatives of 13 species of Staphylococcus were examined using a small-scale procedure for the sequential extraction of isoprenoid quinones and polar lipids. Menaquinones were the only isoprenoid quinones found in the 77 test strains which were divided into three groups based upon the predominant isoprenologue detected: (i) S. hyicus subsp. hyicus, S. sciuri subsp. lentus and S. sciuri subsp. sciuri contained unsaturated menaquinones with six isoprene units; (ii) S. capitis, S. cohnii, S. epidermidis, S. haemolyticus, S. hominis, S. hyicus subsp. chromogenes, S. intermedius, S. saprophyticus, S. simulans, S. warneri and S. xylosus contained unsaturated menaquinones with seven isoprene units and (iii) S. aureus contained unsaturated menaquinones with eight isoprene units and varying amounts of the corresponding lower isoprenologue. All of the organisms contained very similar polar lipid patterns consisting of diphosphatidylglycerol, phosphatidylglycerol, beta-gentiobiosyl diacylglycerol and a number of glycolipids and phospholipids. One of the glycolipids was chromatographically indistinguishable from beta-gentiotriosyl diacylglycerol. Lysylphosphatidylglycerol was a major component in S. aureus and S. intermedius but was usually present in minor amounts in the coagulase-negative strains. The polar lipid data underline the homogeneity of the genus Staphylococcus and distinguish staphylococci from aerobic, Gram-positive cocci and from the phylogenetically related aerobic, endospore-forming bacteria. Menaquinone composition can also be used to separate staphylococci from other aerobic, Gram-positive cocci.     

Glutamine metabolism during aerial mycelium growth of Neurospora crassa

During vegetative growth, glutamine is accumulated in the mycelium of Neurospora crassa. This high pool of glutamine seems to be required for aerial mycelium growth. Enzymes responsible for the synthesis and catabolism of glutamine were measured before and during the partial transformation of a mycelial mat into aerial mycelium. In the transforming mycelial mat,considerable activities of the biosynthetic NADP-glutamate dehydrogenase and glutamine synthetase (predominantly β polypeptide) and also some activity of glutamate synthase were observed. In the aerial mycelium, glutamine synthetase (predominantly β polypeptide) was detected, but very low activities of NADP-glutamate dehydrogenase and glutamate mycelium could derive from glutamine. No glutaminase activity could be detected. It is suggested that glutamate is formed through the activities of the glutamine transaminase-ω -amidase pathway and another transaminase. High activities of glutamine and alanine transaminases were observed in the aerial mycelium. These results are discussed in terms of the possible role of glutamine as a nitrogen carrier from the mycelium to the growing aerial hyphae.     

Addition of an androgen-free epididymal protein extract increases the ability of immature hamster spermatozoa to fertilize in vivo and in vitro

The fertility of spermatozoa from the different epididymal segments of hamsters was tested by in-vivo insemination. Caput and proximal corpus spermatozoa were non-fertile; spermatozoa from the distal corpus epididymidis fertilized 13% (38/290) oocytes and those from the proximal and distal cauda epididymidis 71 and 87%, respectively. When tested by in-vitro insemination, distal corpus spermatozoa penetrated 44% of oocytes while those from the distal cauda fertilized 87% of oocytes. Spermatozoa from the distal corpus recovered in Medium BMOC fertilized 13% (28/219) of oocytes in vivo, while those mixed with an epididymal protein preparation (0.8 mg protein/ml) fertilized 24% (49/204; P less than 0.01) of oocytes. When distal corpus spermatozoa were inseminated in vivo with 0.8 mg epididymal protein preparation 34% (31/90) oocytes were fertilized and only 22% (23/103; P less than 0.05) oocytes were fertilized when the proteins were obtained from epididymides of animals castrated for 30 days. When distal corpus spermatozoa were preincubated for 5 h in medium without (control) or with protein preparation (0.8 or 1.6 mg protein/ml), a significant increase in in-vitro oocyte penetration was found (25 compared with 45%; P less than 0.05) when the protein was present at 1.6 mg/ml. These results confirm and extend previous observations suggesting a role for androgen-dependent glycoproteins secreted by the epididymis in the acquisition of fertilizing ability that occurs during sperm maturation.     

The role of birds as definitive hosts and intermediate hosts of heteroxenous coccidians

Sarcocystis-like oocysts-sporocysts were found in four species of owls (Asio otus, Bubo bubo, Strix aluco, and Tyto alba) and in five species of predatory birds (Accipiter gentilis, Accipiter nisus, Buteo buteo, Circus aeruginosus, Falco tinnunculus). In addition, the muscles of 15 of 41 (36.5%) pheasants (Phasianus colchicus) and one of two jays (Garrulus glandarius) were found to harbor three types of Sarcocystis. Three of 15 (20%) infected pheasants had type I cystozoites (6-8 X 2 microns) in muscle homogenates, but sarcocysts were not seen whereas the other 12 infected pheasants had type II cystozoites (16 X 2-3 microns) and sarcocysts (90 X 600 microns) in their muscles. The one infected jay had type III cystozoites (8-10.5 X 2.5-3 microns) and sarcocysts (35-40 X greater than 770 microns) in its muscles.     

The fibrin-binding site of human plasminogen. Arginines 32 and 34 are essential for fibrin affinity of the kringle 1 domain

Kringle 1 (Tyr 79/Leu 80-His 167 and Tyr 79/Leu 80-Tyr 173), a chymotryptic fragment of human plasminogen that has high affinity for fibrin and omega-aminocarboxylic acids, has been subjected to modification with 1,2-cyclohexanedione to identify arginine residues essential for ligand binding. Reaction of 1,2-cyclohexanedione with kringle 1 was found to rapidly abolish the fibrin-Sepharose affinity of the fragment, whereas the affinity for lysine-Sepharose was lost at a significantly slower rate. Successive affinity chromatography of modified kringle 1 on fibrin- and lysine-Sepharose was used to separate kringle 1 that lost affinity for fibrin-, but retained affinity for lysine-Sepharose from kringle 1 that lost affinity for both affinants. The modified proteins were subjected to structural studies in order to locate the labeled arginine residues in kringle 1. These studies have revealed that modification of Arg 34 leads to the loss of both the fibrin- and lysine-Sepharose affinities of kringle 1, whereas reaction of Arg 32 abolishes fibrin affinity but leaves lysine-Sepharose affinity unaltered. The results suggest that Arg 32 and Arg 34 are both involved in fibrin binding and that Arg 34 is also involved in binding omega-aminocarboxylic acids. Previous NMR studies on kringles have indeed shown that the segment containing residue 34 is in the proximity of and interacts with the omega-aminocarboxylic acid-binding site. This interaction may explain the influence of omega-aminocarboxylic acids on fibrin binding by kringle 1.