Gibberella fujikuroi mutants obtained with UV radiation and N-methyl-N'-nitro-N-nitrosoguanidine

N-methyl-N'-nitro-N-nitrosoguanidine (nitrosoguanidine) and to a lesser extent UV radiation are very mutagenic for Gibberella microconidia. The recommended nitrosoguanidine doses lead to much higher frequencies of mutants than are found in other microorganisms. The frequency of mutants among the survivors increases linearly with the nitrosoguanidine dose (molar concentration X time); the absolute number of viable mutants in a given population reaches a maximum for a dose of ca. 0.7 M X s. The microconidia are uninucleate. The onset of germination brings about increased lethality of nitrosoguanidine, but it does not modify the action of UV radiation. Mycelia are more resistant than spores to both agents. Visible illumination effectively prevents lethality when given immediately after UV radiation. Auxotrophs and color mutants are very easily obtained. Pink adenine auxotrophs and several classes of color mutants are affected in the biosynthesis of the carotenoid pigment, neurosporaxanthin.     

The role of ADP in the modulation of the calcium-efflux pathway in rat brain mitochondria.

The role of ADP in the regulation of Ca2+ efflux in rat brain mitochondria was investigated. ADP was shown to inhibit Ruthenium-Red-insensitive H+- and Na+-dependent Ca2+-efflux rates if Pi was present, but had no effect in the absence of Pi. The primary effect of ADP is an inhibition of Pi efflux, and therefore it allows the formation of a matrix Ca2+-Pi complex at concentrations above 0.2 mM-Pi and 25 nmol of Ca2+/mg of protein, which maintains a constant free matrix Ca2+ concentration. ADP inhibition of Pi and Ca2+ efflux is nucleotide-specific, since in the presence of oligomycin and an inhibitor of adenylate kinase ATP does not substitute for ADP, is dependent on the amount of ADP present, and requires ADP concentrations in excess of the concentrations of translocase binding sites. Brain mitochondria incubated with 0.2 mM-Pi and ADP showed Ca2+-efflux rates dependent on Ca2+ loads at Ca2+ concentrations below those required for the formation of a Pi-Ca2+ complex, and behaved as perfect cytosolic buffers exclusively at high Ca2+ loads. The possible role of brain mitochondrial Ca2+ in the regulation of the tricarboxylic acid-cycle enzymes and in buffering cytosolic Ca2+ is discussed.     

Histamine-immunoreactive cells in the superior cervical ganglion and in the coeliac-superior mesenteric ganglion complex of the rat

Summary Using the immunoperoxidase technique in conjunction with specific antisera to -atrial natriuretic polypeptide (-ANP), it was shown that immunoreactive cell bodies and varicose fibers are widely distributed throughout the rat brain. The highest concentrations of -ANP-containing neuronal cell bodies and fibers were found in the hypothalamus and septum. This result confirms the radioimmunological determination of -ANP immunoreactivity in the rat brain.     

Occurrence of oscillations in ATP synthesis and hydrolysis in chromatophores of Rhodospirillum rubrum

The conditions under which an oscillatory behaviour is observed during net hydrolysis or synthesis of ATP in chromatophores of Rhodospirillum rubrum FR1 are described. In the case of ATPase the oscillations are observed at low temperature (ca. 11°C) in the dark after an initial transient behaviour. These oscillations are attenuated or disappear by the addition of an uncoupler.Oscillations are also observed during ATP synthesis. At 3°C the oscillations appear spontaneously if photophosphorylation is measured during a sufficiently long time. At 30°C the mere intercalation of a dark period also at 30°C is sufficient to trigger the oscillations in the following light period.Abbreviations Bchl Bacteriochlorophyll - FCCP carbonyl cyanide p-trifluoromethoxyphenyl hydrazone - PMS phenazine methosulfate - TMPD, N,N,N,N tetramethyl-1,4-phenylenediamine Dedicated to Prof. Dr. Gerhart Drews as a homage for his permanent example as hard worker and careful scientist and also for his remarkable human quality     

Immunological comparison of glyoxalase I from yeast and mammals and quantitative determination of the enzyme in human tissues by radioimmunoassay

Antibodies to glyoxalase I from yeast, rat liver, porcine erythrocytes and human erythrocytes were raised in rabbits. Gel precipitation and immunotitration experiments demonstrated that the mammalian enzymes were immunologically related, but distinct from the yeast enzyme. Fab fragments of the antibodies to human glyoxalase I did not inhibit the catalytic activity, indicating that the antigen binding sites were not directed towards the active site of the enzyme. A radioimmunoassay for glyoxalase I was developed. Quantitative analysis of human adult as well as fetal organs demonstrated that glyoxalase I was present in a concentration of approximately 0.2 micrograms/mg protein in most human tissues.     

A new syndrome in the group of euhidrotic ectodermal dysplasia

Summary A new form of ectodermal dysplasia was observed in two siblings, offspring of healthy non-consanguineous parents. The main findings in both children are: hypodontia, abnormally shaped teeth, scalp hypotrichosis, pili annulati, follicular hyperkeratosis on the trunk and limbs, intensified delineation and reticular hyperpigmentation of the nape, and hyperopia; one of the siblings also has astigmatism. As both patients have normal nails and are euhidrotic, this is an ectodermal dysplasia of the pilodental subgroup. The cause is probably genetic and autosomal-recessive inheritance is most likely.     

The majority of independently transformed BHK cell clones share a single functional lesion which determines anchorage independence and influences tumorigenicity

Summary Expression of the anchorage-independent transformed phenotype in BHK 21/13 cells generally behaves as a recessive trait. When chemically induced and spontaneously arising transformants are fused to the nontransformed parent line, transformation is initially suppressed, reappearing after extended growth of the hybrids. In this paper, complementation for the expression of anchorage independence was sought among a large group of such transformants, all independently derived from BHK 21/13 cells. Tumorigenicity studies on selected hybrids and parental lines indicated that the in vitro trait of anchorage independence is an accurate indicator of in vivo neoplasia for these cells. Seventeen of the 18 clones tested did not complement one or more of three tester strains. This result indicates that anchorage independence arose in these clones as a result of lesions in the same genetic function and suggests that the final step in the progressive changes of carcinogenesis may frequently be restricted to lesions at a single locus. This investigation was supported by National Institutes of Health grant CA27306.     

Repair of damage in double-stranded phi X174 (RF) DNA due to radiation-induced water radicals

Experiments in which the yields of radiation-induced OH and H radicals were varied, showed that both types of water radicals inactivate phi X174 RF DNA to about the same extent as measured by transfection of the (irradiated) DNA to E. coli wild-type spheroplasts. On the other hand, using spheroplasts prepared from E. coli strains, deficient in one of the proteins involved in excision DNA repair (uvrA- or uvrC-) or in post-replication repair (recA-), clear differences between damage originating from OH or H radical attack were found. Part of the radiation damage due to H radicals appeared to be repairable by an uvrA-gene-dependent repair mechanism, whereas this repair pathway does not play an important role in the case of OH radical damage. The reverse applies to uvrC-gene-dependent repair, which only affects OH radical damage (obtained under anoxic conditions), but has no influence on damage due to H radicals. Irradiation of double-stranded phi X174 (RF) DNA in the presence of oxygen however, yields damage--due to OH radicals only--which appeared not to be sensitive to either uvrC- or uvrA-gene-dependent repair. Furthermore, post-replication repair (recA) has only very little effect on the amount of inactivation by H or OH radicals, when irradiation is carried out under anoxic conditions. We did not find significant inactivation due to hydrated electrons, whether the biological activity was determined by use of wild-type spheroplasts or of strains deficient in excision or post-replication repair proteins.     

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.