Schiffs bases and derived secondary amines as plant growth inhibitors

Seventy-two Schiffs bases, 44 corresponding secondary amines, and 12 N-acetylated compounds were tested on their growth activity. Eighty-one compounds were active as growth inhibitors in at least one of three bioassays.     

The propagation and dispersal of misinformation in ecology: Is there a relationship between citation accuracy and journal impact factor?

The biological and physico-chemical structure of near bottom habitats located under densely growing submerged vegetation, and their significance in the functioning of whole aquatic ecosystems, are very little known due to difficulties in sampling. Corer-type samplers, believed to be the best in littoral studies, do not work properly in such places, because their tube opening is easily clogged by plant shoots, acting as a stopper. In order to overcome this problem, an alteration to the shape of the tube ending is proposed. This can be done by its trimming at an accurate angle, or by fitting (permanently or interchangeably) a metal collar made of stainless steel to its end, so that the ending would resemble the shape of a needle. The modification can be applied to virtually all corer samplers. It was found to be efficient while sampling sediment cores for the purposes of both hydrobiological and paleolimnological studies on heavily overgrown macrophyte-dominated water ecosystems.     

Submarine foraging behavior of alcids in an artificial environment

We used an artificial environment at Sea World, Inc, San Diego, to study underwater foraging behavior of alcids. Larger birds dove longer and had greater wingbeat frequencies. The pigeon guillemot Cepphus columba was the only species to use both feet and wings for propulsion; all others used just wings. Aggressive interactions underwater were common. Competition among alcids in the wild may occur primarily underwater, and artificial environments may be the best means to study such interactions.     

Shifts in Methanogenic Subpopulations Measured with Antibody Probes in a Fixed-Bed Loop Anaerobic Bioreactor Treating Sulfite Evaporator Condensate

A fixed-bed loop, high-rate anaerobic bioreactor treating sulfite evaporator condensate was sampled when it reached steady state and afterwards following perturbations during a 14-month period. By using immunotechnology, it was observed that shifts in methanogenic subpopulations occurred in association with perturbations, such as restarting and relocating the biomass into a different tank. Methanogens related to Methanobacterium bryantii MoHG and Methanobrevibacter smithii ALI were numerous throughout the observation period, while Methanosarcina mazei S6 and Methanosarcina thermophila TM1 were found in the early and late samples, respectively. Also, Methanobacterium formicicum was more numerous at the top portion of the bioreactor, while Methanobrevibacter arboriphilus AZ and DC were at the bottom. Sample formalinization required for prolonged storage proved suitable for antigen preservation.     

Cellular localization of cytochrome c 553 in the N2-fixing cyanobacterium Anabaena variabilis

The in situ location of the electron carrier protein cytochrome C ₅₅₃ (cyt c ₅₅₃) has been investigated in both vegetative cells and heterocysts of the cyanobacterium Anabaena variabilis ATCC 29413 using the antibody-gold technique, carried out as a post-ernbedding immunoelectron microscopy procedure. When using a rabbit polyclonal anti-cyt c ₅₅₃ specific antiserum an intense labelling, associated mainly with the cell periphery (cytoplasmic membrane and periplasmic area), was seen in both heterocysts and vegetative cells. The selective release of most of the cellular cyt c ₅₅₃ during a Tris-EDTA treatment confirms a periplasmic localization of this protein in A. variabilis. The results indicate that most of cyt c ₅₅₃ is located in the periplasmic space. The roles ascribed to this protein in both respiration and photosynthesis in cyanobacteria are discussed.Abbreviations Cyt c ₅₅₃ cytochrome c ₅₅₃ - PBS phosphate buffered saline (20 mM sodium phosphate, 0.9% NaCl, pH 7.4) - PMSF phenylmethylsulfonyl fluoride Recipient of a Research Fellowship of the Alexander von Humboldt Foundation (Bonn, FRG) for a leave to the University of Konstanz.     

Neural network detects errors in the assignment of mRNA splice sites.

The use of databanks in genetic research assumes reliability of the information they contain. Currently, error-detection in the manually or electronically entered data contained in the nucleotide sequence databanks at EMBL, Heidelberg and GenBank at Los Alamos is limited. We have used a subset of sequences from these databanks to train neural networks to recognize pre-mRNA splicing signals in human genes. During the training on 33 human genes from the EMBL databank seven genes appeared to disturb the learning process. Subsequent investigation revealed discrepancies from the original published papers, for three genes. In four genes, we found wrongly assigned splicing frames of introns. We believe this to be a reflection of the fact that splicing frames cannot always be unambiguously assigned on the basis of experimental data. Thus incorrect assignment appear both due to mere typographical misprints as well as erroneous interpretation of experiments. Training on 241 human sequences from GenBank revealed nine new errors. We propose that such errors could be detected by computer algorithms designed to check the consistency of data prior to their incorporation in databanks.     

Different numbers of maternal and paternal siblings of cystic fibrosis patients

Summary When 458 parents of children suffering from cystic fibrosis (CF) from all over the German Democratic Republic were interviewed to determine the number of their siblings, it was found that the maternal families had a total of 1369 children and the paternal, 1220. While the fathers of CF patients tended to originate from families with one or two children, more mothers than fathers came from families with three to twelve children (P=0.01). The average number of children in the maternal families was 2.99; in the paternal families, only 2.66. To rule out any methodological errors, sibs of mothers and fathers of various control groups were studied. We found that the number of siblings in these groups was balanced. The differences in our findings are probably due to CF heterozygosity. The underlying mechanism is unknown.     

Recovery of adenine-nucleotide pools in terrestrial blue-green algae after prolonged drought periods

Summary The response of Nostoc commune and Nostoc flagelliforme (terrestrial blue-green algae), grown in their natural habitat, towards rewetting after prolonged drought periods (2 weeds up to five years) has been investigated. In Nostoc flagelliforme, the energy charge (EC) about 0.18 in dry condition increases rapidly (EC=0.7 after 1 h) and more slowly in a second phase (EC=0.8 after 6 h). The total content of AXP (=ATP+ADP+AMP) apparently increases due to de novo synthesis of adenine nucleotides. ATP-build-up after a drought period is probably provided by oxidative phosphorylation. It has been found to be about the same, regardless of whether the foregoing drought period had been extended over 6 months or 5 years.Dry samples of colony mats of N. commune exhibit very low ATP-, but high ADP-contents. Within 6 h after rewetting, the final level of extractable ATP (60–100 nmol/mg chlorophyll) is recovered.