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Notes: Zusammenfassung Zur Prüfung der Frage einer experimentell erzeugbaren Autoimmunisierung gegen Lebergewebe beim Hund wurden 5 Tiere aktiv mit subcellulären Leberfraktionen vom Schaf (zusammen mit compl. Freundschem Adjuvans) immunisiert. Bereits 3 Wochen nach Immunisierungsbeginn waren bei allen Hunden komplementbindende Antikörper gegen autologes und heterologes Lebergewebe nachweisbar. Das heterologe Antiserum erwies sich als nicht streng leberspezifisch. Die pathogenetische Bedeutung der antihepatischen Autoantikörper soll an Hand weiterer Untersuchungen (Histologie, bioptisch gew. Lebergewebes, Pfortaderdruckmessungen, Leberfunktionsproben) geprüft werden.

Notes: Abstract In outdoor tanks enclosed monocultures of Thalassiosira rotula showed partly synchronized cell divisions during exponential growth. The changes in division activity showed a characteristic frequency, which also could be found for cell length (pervalvar axis) and assimilation rate as well as for concentration changes of dissolved free amino acids (DFAA) and ammonia. Excretion of DFAA occurred preferentially during periods of reduced cell division activity, when assimilation was at a higher level. The concentration of ammonia decreased during these periods. The rates per hour of these parameters showed significant multiple correlations. The release of six individual amino acids (ala, β-ala, gly, lys, orn and ser) seemed to be controlled by the physiological status of the diatoms. These amino acids amounted to a portion of about 70–80% of the total DFAA. Uptake and release rates of DFAA nitrogen and ammonia were in the same range with maxima of about 350 ng at nitrogen dm-3 h-1 and litre. These dynamics pointed to strong fluxes of organic bound nitrogen in marine micro-heterotrophs.

Notes: Abstract The effects of food limitation on growth rates and survival of marine invertebrate larvae have been studied for many years. Far less is known about how food limitation during the larval stage influences length of larval life or postmetamorphic performance. This paper documents the effects of food limitation during larval development (1) on how long the larvae ofCrepidula fornicata (L.) can delay metamorphosis in the laboratory after they have become competent to metamorphose and (2) on postmetamorphic growth rate. To assess the magnitude of nutritional stress imposed by different food concentrations, we measured growth rates (as changes in shell length and ash-free dry weight) for larvae reared in either 0.45-μm filtered seawater or at phytoplankton concentrations (Isoehrysis galbana, clone T-ISO) of 1 × l03, 1 × 104, or 1.8 × 105 cells ml−1. Larvae increased both shell length and biomass at 1 × 104 cells ml−1, although significantly more slowly than at the highest food concentration. Larvae did not significantly increase (p 〉 0.10) mean shell length in filtered seawater or at a phytoplankton concentration of only 1 × 103 cells ml−1, and in fact lost weight under these conditions. To assess the influence of food limitation on the ability of competent individuals to postpone metamorphosis, larvae were first reared to metamorphic competence on a high food concentration ofI. galbana (1.8 × 105 cells ml−1). When at least 80% of subsampled larvae were competent to metamorphose, as assessed by the numbers of indlviduals metamorphosing in response to elevated K+ concentration in seawater, remaining larvae were transferred either to 0.45-μm filtered seawater or to suspensions of reduced phytoplankton concentration (1 × 103, 1 × 104, or 5 × 104 cells ml−1), or were maintained at 1.8 × 105 cells ml−1. All larvae were monitored daily for metamorphosis. Individuals that metamorphosed in each food treatment were transferred to high ration conditions (1.8 × 105 tells ml−1) for four additional days to monitor postmetamorphic growth. Competent larvae responded to all food-limiting conditions by metamorphosing precociously, typically 1 wk or more before larvae metamorphosed when maintained at the highest food ration. Surprisingly, juveniles reared at full ration grew more slowly if they had spent 2 or 3 d under food-limiting conditions as competent larvae. The data show that a rapid decline in phytoplankton concentration during the larval development ofC. fornicata stimulates metamorphosis, foreshortening the larval dispersal period, and may also reduce the ability of postmetamorphic individuals to grow rapidly even when food concentrations increase.

Notes: Resistance tests of 127 parsley accessions (Petroselinum crispum) were carried out during 2 years of field investigations involving natural infection for black leaf spot (Alternaria radicina), mildew (Erysiphe heraclei), leaf chlorosis (Fusarium oxysporum) and viruses, particularly celery mosaic virus (CeMV). In this first extensive evaluation of parsley for all tested pathogens accessions were found to be free of symptoms.Varieties of vars. crispum and tuberosum contained more accessions weakly infected or immune to black leaf spot than vars. vulgare and neapolitanicum. In a separate test five var. crispum accessions showed significantly reduced disease ratings, indicating their potential as sources of resistance. Mildew attacked almost the same number of accessions in both years: 29 accessions of var. crispum showed no symptoms, but 16 of the var. tuberosum accessions were highly susceptible. Whereas in the var. vulgare one half of the introductions were moderately or strongly infected by viruses, mainly CeMV, a high number of plants remained uninfected in the vars. crispum, neapolitanicum and tuberosum. In the case of F. oxysporum, the greatest amount of infection was in the var. crispum during both years. The sources of resistance described including multiple resistance would be of interest in future breeding programmes for resistance to the parsley pathogens discussed.

Notes: Plasmid DNA containing deoP1, one of the two major promoters of the deo operon, has been mutagenized using hydroxylamine, and promoter down-mutations and operator mutations were selected. The isolated mutants are all located within a 16bp palindromic sequence containing the –10 region of deoP1. The results show that RNA polymerase and DeoR repressor compete for the same DNA target. The deoP1 promoter activity is dependent on a TG motif one base pair upstream of the –10 consensus sequence. The sequence of the deo operator site was further verified by use of a synthetic linker.

Notes: Transcriptional regulation of the deoP2 promoter by the cyclic AMP/cyclic AMP receptor protein complex (cAMP/CRP) and the CytR repressor requires two high-affinity CRP targets located around -41 and -93 bp preceding the start site for transcription. Here we report the structure of cddP, another CRP/CytR-regulated promoter. In common with what was found in deo, the cdd promoter also contains multiple CRP targets. Thus, using the DNasel footprinting procedure, tandem CRP binding sites were identified around -41 and -93. These findings support a general model for CytR binding and CytR regulation, in which (i) CytR and the CRP/cAMP complex bind to similar or Identical targets, (ii) two or more targets are necessary for proper binding of CytR to a promoter region, and (iii) CytR represses transcription by antagonizing cAMP/CRP activation.

Notes: Abstract Dissolved organic substances (carbohydrates, organic nitrogen, free amino acids) were measured in the German Bight (North Sea) in June, 1981. During and before this survey, sea foam was observed in the east Frisian coastal water and it accumulated on the nearby beaches to an unusually high extent. In this coastal water area, a large Phaeocystis pouchetii Lagerheim bloom and very high concentrations of dissolved organic matter were found. The above dissolved organic substances were all positively correlated to a highly significant degree with P. pouchetii cell numbers in the bloom area. An influence of salinity (or river water) on this correlation could be excluded. Thus, exudation or decomposition products of P. pouchetii were most likely the cause of the unusually high concentrations of dissolved organic matter in the bloom area off the east Frisian coast, where P. pouchetii blooms have been reported for many years. Ammonia concentrations were very low in the P. pouchetii bloom area; this and the accumulation of dissolved organic substances might lead to speculation that decomposition of dissolved organic matter by bacteria could have been reduced due to antibiotic activity of P. pouchetii.