James H. Rittenburg

Studies on the Mineral Requirements of the Adults American Lobster

Abstract In a series of laboratory and field studies, the effects of dietary mineral supplements were tested on adult lobsters (Homants americanus). Both semipurified diets and diets formulated from commercial ingredients were used. Results of these studies indicated that the optimum ratio of calcium and phosphorus (Ca:P) for adult lobsters was about 1:1, which agrees with optimum levels determined previously for juvenile lobsters. Results also indicated that added mineral supplements are of no particular benefit to adult lobsters in diets formulated for commercial use in pounds, as long as the ash present in the commercial ingredients has a Ca: P ratio near 1:1.

A rapid technique for preparing microorganisms for transmission electron microscopy.

A rapid and efficient method of preparing microorganisms for transmission electron microscopy is reported. In developing the method Salmonella, streptococcal, and protozoal specimens were fixed with glutaraldehyde. After fixation cells are collected on a membrane filter, washed with buffer, postfixed with osmium tetroxide, then washed with distilled water and stained en bloc with uranyl acetate. Specimens are dehydrated using a graded series of acetone and then infiltrated with graded mixtures of acetone and Spurr embedding medium. Finally the membrane filter is cut into small pieces and embedded in fresh embedding medium polymerized in polyethylene capsules. By collecting and processing the specimens on membrane filters, numerous centrifugations are eliminated from standard procedures. The use of a low viscosity embedding medium allows for rapid infiltration and embedding of the specimen. Using this technique microbial specimens can be sectioned after less than 4 hours preparation.

The Effect of Aerococcus viridans (var.) homari on the Oxygen Binding Capacity of Hemocyanin in the American Lobster (Homarus americanus)

Abstract The effect of gaffkemia (Aerococcus viridans) infection on the oxygen binding capacity of the hemocyanin component of the American lobsters hemolymph was examined both in vivo and in vitro. Spectrophotometric and electrophoretic examination of the hemocyanin indicated that accompanying gaffkemia infection was a 50% reduction in the oxygen binding capacity of the hemocyanin. Serum protein levels were unaffected by the infection. In vitro growth of A. viridans in lobster sera resulted in similar findings. Death from gaffkemia may be a result of hypoxia arising from bacterial impairment of the lobsters respiratory exchange system, rather than a result of nutrient depletion as has previously been reported.

A comparison of techniques for the measurement of growth in adult lobsters

Abstract Four non-destructive measures of growth (wet weight in air, wet weight in water, displacement volume and carapace length) were correlated to two destructive measures of growth (dry weight and total body protein level) in adult American lobsters ( Homarus americanus ). All non-destructive parameters were significantly ( P

Photoelectric measurement of lobster (homarus americanus) response to feed attractants

Abstract The apparatus described was designed to measure the speed and direction of lobster response to feed attractants with minimal observer influence on the test animal. Lobster activity was monitored in an 84 × 10 × 10 in (213 × 25 × 25 cm) plexiglas tank based on interruption of photoelectric cells. Impulses from the photocells trigger the pens of a 6-channel event recorder. During its operation the apparatus is covered with an opaque plastic sheet. Lobster behavior was such that the animals always settled in one of the chamber ends and the test material could be injected at the far end. The lobsters responded to a variety of test materials.