Raymond J. Lewis

Wheaton College Illinois · Biology

Earth systems, when understood and respected, have the intrinsic capability to be instrumental for sustainable international development. If applied wisely without sophisticated technology, natural processes themselves can serve to sustain and prosper life in specifi c situations. Global initiatives to provide safe surface and groundwater are boomi...

Though billions of people are without adequate fresh-water resources, even more people lack effective sanitation services. This latter concern is the focus of an appropriate technology initiative (WASTE Programme) of Wheaton College in Illinois which engages undergraduate students and interdisciplinary faculty in experiments with simple, small-scal...

The supply of iron has been reported to affect gametogenesis in the gametophytes of some species of kelps (order Laminariales). Spores of the kelps Alaria marginata Postels & Ruprecht, Dictyoneurum californicum Ruprecht, Egregia menziesii (Turner) Areschoug, Laminaria setchellii Silva, and Macrocystis pyrifera (L.) C. Agardh were cultured in enrich...

Brown algae are critical components of marine ecosystems around the world. However, the genome of only one species of the class has so far been sequenced. This contrasts with numerous sequences available for model organisms such as higher plants, flies or worms. The present communication expands our coverage of DNA content information to 98 species...

Hybridization was attempted by combining gametophytes between intergeneric pairs among the following taxa in the Lessoniaceae: Macrocystis pyrifera (L.) C. Agardh, M. integrifolia Bory, M. angustifolia Bory, Pelagophycus porra (Leman) Setch., Nereocystis luetkeana (Mert.) Post & Rupr., Dictyoneurum californicum Rupr., and Dictyoneuropsis reticulata...

Gametophytes of the ‘sea palm’, the kelp Postelsia palmaeformis Ruprecht, produced gametes whether or not chelated iron was supplied in the culture medium, in contrast to the inhibition of gametogenesis seen with the absence of iron in many other kelps. As gametogenesis proceeded, every cell of the gametophytes was converted into a gamete so that t...

Parthenogenetic sporophytes were obtained from three strains of Laminaria japonica Areschoug. These sporophytes grew to maturity in the sea, producine spores that all grew into female gametophytes. These female gametophytes gave rise to another generation of parthenogenetic sporophytes during the next year, so that by the year 1990 parthenogenetic...

All combinations of individuals of Macrocystis pyrifera (L.) C. Agardh, M. integrifolia Bory, and M. angustifolia Bory hybridized. Gametophyte isolates obtained from 18 individuals were used, including M. pyrifera and M. integrifolia from the extremes of their Northern Hemisphere ranges along the Pacific Coast of North America and M. pyrifera and M...

Branching of tetrasporophytes and gametophytes of Ceramium codicola was characterized by the Strahler method of ordering branches and by measuring angles of ordered branches in order to quantify differences in morphology between these 'isomorphic' reproductive stages. Numbers of ordered branches varied between the stages, with female and male gamet...

Mentoring students in investigative research is a key part of actively engaging them in learning biology. While this is best accomplished by involving students in individualized research projects, it is not always feasible to offer such an opportunity to all students. A course in Biological Research that focuses on doing research with a particular...

Gametogenesis in several species of kelp gametophytes was investigated in relation to the supply of chelated iron (Fe-EDTA) in the culture medium. Spores of Laminaria setchellii, Egregia menziesii, Alaria marginata, Dictyoneurum californicum, and Macrocystis pyrifera were grown in Provasoli's Enriched Seawater with and without added Fe-EDTA. All sp...

Achnanthes longipes Ag. is a marine stalk-forming diatom that grows in dense biofilms. The effects of cell density, temperature, and light on growth and stalk production were examined in the laboratory to determine how they affected the ability of this diatom to form a biofilm. Stalk production abruptly increased when A. longipes was cultured at a...

Most red algae with a Polysiphonia-type life history are regarded as having isomorphic phases. However, some show minor deviations in morphology, including differences in branching reported in female gametophytes and tetrasporophytes of Ceramium. By sampling populations of Ceramium codicola, an epiphyte of Codium fragile, it was possible to charact...

Genetic variation in 126 clones of the planktonic diatom,Fragilaria capucina, collected from seven lakes from Manitoba to Texas, was determined by RAPD analysis. Five primers yielded 48 scorable RAPD fragments in 123 unique combinations. Patterns of genetic variation were analysed by cluster analysis, which showed that most clones grouped together...

Gracilaria strain G-16S was cultured in various phosphorus (P) supply rates with low or high nitrogen (N) supply to determine the effects of nutrient supply on its productivity, agar content and physical properties of the agar. Productivity was reduced after four weeks of growth in zero P supply as plants reached 0.07% P tissue content (critical le...

Investigations concerning brown algal chromosomes have contributed to our understanding of the reproductive biology of brown algae. Techniques used in observing chromosomes in the light microscope are briefly summarized. Mitosis and meiosis are discussed, with an emphasis on aspects that are distinctive in the brown algae. Observations of chromosom...

Field and laboratory experiments were used to investigate the spatial scale of benthic effects of an active nearshore produced-water (=aqueous wastes of oil and gas production) outfall on various components of recruitment in the giant kelp Macrocystis pyrifera. Results showed that discernible effects on all parameters measured were limited to areas...

Point sources of pollution (e.g. industrial and municipal outfalls) may produce ecological impacts at distant locations if pollutants affect dispersive propagules. We used laboratory experiments to determine how water-column exposure to produced water (=the aqueous fraction of oil and gas production that is typically discharged into coastal waters)...

Point sources of pollution (e.g. industrial outfalls) may produce ecological impacts at distant locations if pollutants affect dispersive propagules. The authors used laboratory experiments to determine how exposure to produced water (PW; aqueous fraction of petroleum production that is typically discharged into coastal waters) in the water column...

Three species of Macrocystis occur in California: M. pyrifera, M. angustifolia and M. integrifolia. Gametophytes isolated from them were grown in the laboratory. Male and female gametophytes were crossed in the laboratory in all possible combinations. Normal F1 sporophytes were obtained from all crosses and eventually grown in the sea near Santa Ba...