The necessity of manganese for the growth of both autotrophic and heterotrophic plants was reported first by Bertrand (5, 6) more than 50 years ago, and the essentiality of manganese for the growth of Chlorella was shown originally by Hopkins (20) of Cornell University in 1930. The relation of manganese to photosynthesis was suspected by McHargue (24) and Bishop (7). However, it was not until 1...

It is known that the zooplankter Daphnia induces colonies in the alga Scenedesmus. As Daphnia grazes on Scenedesmus, it has been postulated that colony formation represents an algal defense mechanism. This induction of Scenedesmus coenobia/colonies by Daphnia could be associated with a substance exuded by the animals that acts as a specific infochemical (kairomone) for Scenedesmus. However, the...

Synchronous populations of the chlorococcal alga Scenedesmus quadricauda were subjected to various irradiances, photoperiods, heterotrophic growth and chloramphenicol treatment in order to induce different cell cycle patterns. The courses of cellular and nuclear division, and of commitments to them, were followed to measure duration of growth and reproductive steps and to analyze their mutual i...

The photosynthetic activity of the green alga Scenedesmus quadricauda was investigated during synchronous growth in light/dark cycles. The rate of O2 evolution increased 2-fold during the first 3 to 4 h of the light period, remained high for the next 3 to 4 h, and then declined during the last half of the light period. During cell division, which occurred at the beginning of the dark period, th...

Ecotoxicological endpoints based on behavioral traits (e.g., predator avoidance, feeding, and locomotion) may be more sensitive and give more insights into patterns of sublethal toxicity than survivorship tests. In this study, the density-dependent grazing rate of Daphnia pulex pre-exposed to p,p'-dichlorodiphenyldichloroethylene (DDE) (insecticide metabolite) and glyphosate (herbicide), via wa...

The complete amino acid sequence of ferredoxin isolated from a green alga, Scenedesmus species, was determined by analyses of tryptic and chymotryptic digests, and cyanogen bromide cleavage of the S-carboxymethylcysteinylferredoxin. The total number of amino acid residues is 96, one less than for the higher plant ferredoxins. It is the first chloroplasttype ferredoxin found lacking in tryptopha...

releasing of textile dye effluents into general water bodies is a major environmental and healthproblem. color removal, in particular, has recently become of major scientific interest, as indicated by themultitude of related research reports. during the past two decades, several physico-chemical decolorizationtechniques have been reported, few, however, have been accepted by the textile industr...

The green alga Scenedesmus is known for its phenotypic plasticity in response to grazing risk. However, the benefits of colony formation induced by infochemicals from zooplankton should come with costs. That is, a tradeoff in benefit-to-cost ratios is likely under complex environmental conditions. In this study, we hypothesized that the coexistence of Scenedesmus and its competitors decreases t...

U. C. Vothknecht* and D. Dörnemann Fachbereich Biologie/Botanik, Philipps-Universität Marburg, Karl-v.-Frisch-Straße, D-35032 Marburg, Bundesrepublik Deutschland Z. Naturforsch. 50c, 789-795 (1995); received June 16/August 28, 1995 C5-Pathway, Glutamyl-tRNAglu-Synthetase (E.C.6.1.1.17), Misacylation of tRNAglu, Amidotransferase, Scenedesmus obliquus In a previous paper we described the purifica...