George M. Briggs

The Growth-Promoting Activity of Several Lipid-Related Compounds in the Free-Living Nematode Caenorhabditis briggsae

Summary The growth-promoting activities of a number of lipid-related chemical compounds were studied in C. briggsae. It was found that several such compounds, Tween 80 (20 mg/ml), Tween 85 (10 mg/ml), sodium oleate (1.0 mg/ml), sodium stearate (1.0 mg/ml), ethanol (4.0 mg/ml), n-propanol (4.0 mg/ml), and potassium acetate (5.0 mg/ml), greatly stimulated population growth in C. briggsae and were much more potent than a casein hydrolysate (casamino acids). These findings have led to the recognition of a lipid-related factor for C. briggsae and to the successful development of a completely chemically defined medium for the cultivation of C. briggsae without the presence of a protein-aceous factor.

Effect of particulate materials on population growth of the free-living nematode Caenorhabditis briggsae.

Summary Several particulate compounds such as Celite, glass powder, tin oxide, diamond powder, and three different cellulose products, Microcrystalline Cellulose, Solka Flok, and Cellophane Spangles, stimulated population growth in C. briggsae. Since inert diamond particles form a poor adsorbent, and since large particles did not enter the gut of the nematode, our results suggest that stimulation is not the result of nutrient adsorption or phagocytosis, but rather due to the physical presence of particles.

A Study of Mineral Requirements in Caenorhabditis Elegans

The quantities of Mg+2, Na+ , K+ , Mn+2, Ca+ and Cu+2 required by the free-living nematode C. elegans were determined. An individual mineral deficiency was developed by deleting the mineral from the basal medium. Quantitative requirements of individual minerals were determined respectively by adding each mineral at various concentrations to the depleted medium. Serial subcultures and biological pre-treated media were used for the development of Mn+2, Ca+2 and Cu+2 deficiencies. It was found that most C. elegans were supported at 73 μg/ml Mg+2, 300μg/ml Na+, 530 μg/ml K+ , 6.3 μg/ml Mn+2,1500 μg/ml Ca + 2 and 7.2 μg/ml Cu+2.

Unidentified growth factor(s) present in alfalfa water-solubles for young guinea pigs.

Summary At least one unidentified factor is present in alfalfa which stimulates growth (and may alter hematological values) in young guinea pigs. These factor (s) are organic, water soluble, partially methanol soluble, heat stable, and of relatively large molecular size (> 5000 mol wt) or attached to large molecules. They are active at low levels (1% or less) in a purified basal diet. Further studies are in progress to characterize these factors.

Biotin deficiency in mice and depigmentation, effect of dietary carbohydrates.

Summary Uncomplicated and reversible biotin-deficiency symptoms such as retarded growth, poor appearance, changes in skin, and impaired hair development and depigmentation were developed in young black mice by the inclusion of antibacterial agents in purified rations but without the use of dried egg white. The severity of the deficiency and the prevalence of depigmentation of the hair appeared to vary with the carbohydrate portion of the diet. The most severe deficiencies were obtained when a combination of glucose, sucrose, starch, and cellulose were fed in the diet.