Biochemical and spectroscopic analysis of UV effects in the marine flagellate Cryptomonas maculata

The effects of solar and artifical ultraviolet radiation on the marine cryptoflagellate, Cryptomonas maculata, were studied. Even after short exposure to UV the accessory photosynthetic pigment phycoerythrin is bleached; likewise the fluorescence undergoes significant changes both in amplitude and in the maximal peak wavelength. In parallel, the photosynthetic oxygen production decreases rapidly during exposure. Gel electrophoresis and FPLC of membrane proteins show a significant decrease in chromoproteins after 2 h UV, which is confirmed by fluorescence excitation and emission spectra of the FPLC fractions.Abbreviations APS ammonium persulfate - DCMU 3-(3,4dichlorophenyl)1,1-dimethylurea; Emulphogen, polyoxyethylene 10 tridecyl ether - FPLC fast protein liquid chromatography - PMSF phenylmethylsulfonyl fluoride - SDS sodium dodecylsulfate - SDS PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis - TEMED NN NNtetramethylethylene diamine - UV-A wavelength range between 320 nm and 400 nm - UV-B wavelength range between 280 nm and 320 nm Dedicated to the 60th birthday of Professor Dr. W. Wehrmeyer     

Initial stages in the course of adventitious bud formation on embryos of Picea abies

Adventitious buds on embryos of Picea abies (L.) Karst. developed after a pulse treatment with 250 μ M benzyladenine (BA) of pH 5.5 for 2 h. Light and temperature regimes were not critical during the initial stages. Adventitious buds developed faster after a pulse treatment and the variation among different experiments was lower compared to when the embryos were cultured on media supplemented with BA. Various stages of the differentiation of adventitious buds were identified: stage 1 - appearance of meristematic centres (approximately the first two weeks); stage 2 - development of adventitious bud primordia (approximately the third week); stage 3 - adventitious bud development (from approximately the 4th to the 8th week). This system may be used for further studies on bud differentiation.     

Studies on mutagen-sensitive strains of Drosophila melanogaster. V. Biochemical characterization of a strain (ebony) that is UV- and X-ray sensitive and deficient in photorepair

We investigated larval sensitivity to UV and repair of UV- and X-ray-induced lesions in the DNA of the ebony strain compared to a wild-type strain (Canton S). The ebony strain was previously characterized as being more sensitive to UV-induced killing of embryos than Canton S. Also the ebony strain is more sensitive to X-rays for induction of larval killing, dominant lethals and recessive lethals. In this paper it is demonstrated that (1) ebony larvae are more sensitive to killing by UV and less proficient in photoreactivation (PR) ability than Canton S larvae; (2) the ebony strain has a defect in PR repair of endonuclease-sensitive sites induced in the DNA of primary cell cultures by UV irradiation; (3) the ebony strain has a defect in the repair of single-strand breaks induced in the DNA by X-rays (again in primary cell cultures), at least early on in the repair incubation. A rough localization of the UV sensitivity and the PR ability is presented and the possible relevance of the biochemical to the genetic results is discussed.     

Effect of presowing seed treatment with molybdenum and cobalt on growth,nitrogen and yield in bean (Phaseolus vulgaris L.)

Summary Bean (Phaseolus vulgaris L. Cv. Burpees Stringless) seeds were subjected to two cycles of presowing soaking and drying treatments with sodium molybdate and cobalt nitrite at 1 and 5 ppm concentrations used separately and also in combination. Sodium molybdate 2 ppm and cobalt nitrite 1 ppm used singly proved better than the remaining treatments with respect to nodulation, dry matter, nitrogen and yield. Combined treatment with sodium molybdate and cobalt nitrite did not produce additive effect on any parameter studied compared to their usage alone.     

Differential Degradation of Different Benzodiazepine Binding Proteins by Incubation of Membranes from Cerebellum or Hippocampus with Trypsin

When rat brain membranes were incubated with [3H]flunitrazepam in the presence of UV light, predominantly one protein (P51) was irreversibly labeled in cerebellum and at least two proteins (P51 and P55) were labeled in hippocampus. On digestion of membranes with increasing concentrations of trypsin up to 40% of radioactivity irreversibly bound to proteins was removed from the membranes. In addition, P51 was nearly completely degraded to a peptide with apparent molecular weight 39,000 and this peptide was further degraded to a peptide with apparent molecular weight 25,000. In contrast, protein P55 was only partially degraded by trypsin and yielded two proteolytic peptides with apparent molecular weights 42,000 and 45,000 which seemed to be rather stable against further attack by trypsin. Membranes treated with trypsin still had the capacity to bind [3H]-flunitrazepam reversibly with an affinity similar to that of membranes not previously treated with trypsin. When these membranes were irradiated with UV light, the same proteolytic peptides were detected as in membranes first photolabeled and then digested with trypsin. These results suggest a close association between reversible and irreversible benzodiazepine binding sites and indicate that membrane-associated proteins P51 and P55 are differentially protected against degradation by trypsin.     

Morphological studies of polycystic mouse ovaries induced by dehydroepiandrosterone

Summary Morphological alterations induced by dehydroepiandrosterone (DHA) were studied in polycystic mouse ovaries (PCO). Treated mice showed ovulatory failure and cystic changes; cysts and follicles in various stages of growth and atresia were present although corpora lutea were absent. The levels of testosterone, dihydrotestosterone, 3- and 3-androstanediol, estrone and androstenedione increased, whereas estradiol was not detectable.The ultrastructure of granulosa cells in healthy and atretic follicles was similar to that of control animals, although the membrana granulosa in cysts was reduced to a monolayer of flattened cells. The theca interna of healthy and atretic follicles and ovarian cysts showed ultrastructural signs of abnormal steroidogenic stimulation.No significant differences (0.7<P<0.8) were found between the extensive surface area of gap junctions of healthy follicles of control and DHA-treated animals. On the P-face of granulosa cells of large healthy follicles, meandering strands of tight junctional particles were observed; their average length was significantly longer than those in healthy follicles of control animals (P<0.001). This increase was probably related to the large amounts of androgens present in the treated animals.Theca interna cells possessed small gap junctions; no significant differences (P>0.9) in gap-junction surface area were observed between DHA-treated and control animals. These results suggest that the size of gap junctions is probably unrelated to the steroidogenic activities of theca cells.The following trivial names have been used: Dihydrotestosterone: 5-androstan 17 ol-13 one; 3-androstanediol: 5-androstan 3,17 diol; 3-androstanediol: 5-androstan 3,17 diol     

Segments of chromosomal DNA from Rhynchosciara americana that undergo additional rounds of DNA replication in the salivary gland DNA puffs have only weak ARS activity in yeast

We have constructed a library of recombinant phage containing DNA from salivary gland chromosomes of Rhynchosciara americana. We have isolated phage from this library that carry sequences homologous to cDNA clones that hybridize in situ to the DNA puffs at the polytene chromosome regions C3 and C8. This has enabled us to demonstrate a 16-fold amplification of the genomic DNA sequences at these regions during DNA-puffing. At the C8 site there is a sequence element that has characteristics of 'scrambled' moderately repetitive DNA. This is located within 3 kb from the gene encoding a 1.95-kb mRNA. We have assayed restriction fragments from the two DNA puffs for Ars activity in yeast. The only strong Ars activity is associated with a part of the moderately repetitive DNA element from the C8 puff which is not present at this site in all animals.     

The araBAD operon of Salmonella typhimurium LT2. I. Nucleotide sequence of araB and primary structure of its product, ribulokinase

Hybrid plasmids containing the araBAD operon of Salmonella typhimurium LT2 were characterized by Southern blot and genetic analyses. The nucleotide sequence of araB was determined. The araB gene product, ribulokinase (EC 2.7.1.16), was purified and the results of amino acid composition analysis and partial amino acid sequence are in agreement with predictions from the DNA sequence. Ribulokinase is 569 amino acid residues long and has a calculated Mr of 61 793. Ribulokinase shares significant homology with xylulose kinase from Escherichia coli. Codon usage in the araB gene does not favor those codons which have intermediate codon-anticodon binding energy.     

Thiol-stimulated secretion of riboflavin and porphyrins by Escherichia coli

Abstract Streptococcus lactis strain IL594 contains 9 plasmids, designated pIL1 to pIL9. On the basis of protoplast-induced curing experiments we showed that derivatives containing pIL7 (31 kb) were resistant to UV-irradiation while derivatives lacking pIL7 were sensitive. The pIL7-determined UV-protection was confirmed by cotransfer of the plasmid and of the character into a plasmid-free derivative of S. lactis IL594. Moreover, prophage induction required higher UV-fluence in this derivative carrying pIL7 than in the plasmid-free strain. This is the first report of a plasmid-mediated UV-protection in group N streptococci.     

A Hypernychthemeral Sleep-Wake Syndrome: A Treatment Attempt

The wake and sleep-onset times of a patient with a sleep-wake cycle longer than 24 hr were recorded by the patient for 4 years. During this time, the patient found himself unable to maintain a 24-hr sleep-wake schedule. When treated with 1-2 mg clonazepam, taken nightly, he was able to become entrained to a 24-hr day. Despite entrainment of his sleep-wake cycle, the patient reported depression, lack of motivation and fatigue and chose not to continue taking the drug.