Mixed function oxidase activity in the harbour seal (Phoca vitulina) from Sable Is., N.S

One adult male, eight pups (including two full term foetuses) and nine adult female harbour seals (Phoca vitulina) were analysed for indices of mixed function oxidase (MFO) activity. MFO activity was present in liver samples, but was at or below detection limits in samples of kidney, lung and pancreas. Hepatic ethoxyresorufin O-de-ethylase and benzo[a]pyrene hydroxylase activities were similar to those reported in other seals and in other mammals. Cytochromes P-450 and b5 concentrations were slightly lower than those observed in other mammals. MFO activities in newborn pups and foetuses were significantly lower than those in adult females. No qualitative differences in cytochrome P-450 isozyme distribution between foetal and adult samples could be discerned by electrophoresis.     

THE EFFECTS OF VARIOUS SUBSTANCES ON THE COMPARATIVE GROWTH OF EXCISED TOMATO ROOTS OF CLONES CARRYING DWARF AND NORMAL ALLELES

Lee , Addison E. (U. Texas, Austin.) The effects of various substances on the comparative growth of excised tomato roots of clones carrying dwarf and normal alleles. Amer. Jour. Bot. 46(1) : 16-21. Illus. 1959.—Excised tomato roots carrying the wd gene for dwarfness and its comparable normal allele, wd+, were cultured under various conditions in an effort to provide information as to the physiological differences between the 2 root clones. Two percent is the optimal sucrose concentration for both roots, although wd roots appear to be relatively more tolerant to high sucrose concentration than wd+ roots. The addition of yeast extract, casein hydrolysate, 1, 3-diphenylurea, and a combination of the last 2 in standard medium fail to improve growth of either wd or wd+ roots. The growth of wd roots is favored by the dark while that of wd+ roots is favored by the light. The addition of IAA to the medium fails to stimulate either type. The effects of eosin added to the medium in various concentrations were studied. High concentrations were inhibitory, but the effect of a concentration of 10^-9 g./ml. provided some evidence of an auxin differential between the two clones of roots. The effects of antiauxins were also investigated, but all of those used reduced the growth of both wd and wd+ roots. It was concluded that although there may be some differences in the auxin metabolism between wd and wd+ roots, it is not likely that this is the cause of dwarfism in the wd roots. Kinetin was found to stimulate both wd and wd+ roots in a concentration of 1.0γ/l. but the stimulation was not differential. Gibberellic acid was found to inhibit both wd and wd+ roots in relatively high concentrations. It had little effect on wd roots in relatively low concentrations, but was inhibitory to wd+ roots even in very low concentrations. Thus these substances appear not to be the cause of the dwarf condition of the wd roots.     

A growth chamber for the production of 14C-labeled salt marsh plants and its application to smooth cordgrass, Spartina alterniflora Loisel

An inexpensive growth chamber of simple construction is described and is shown suitable for the culture of Spartina alterniflora Loisel in a labeled (¹⁴CO₂) atmosphere. The smallest plants were least tolerant to transplant and trimming. The biomass which survived transplant was ≈ 684 g dry weight/m². Carbon dioxide uptake and O₂ evolution by growing plants and associated benthic microalgae were followed for 2 months. Increase of Spartina biomass indicated a whole plant net production of 713 g dry weight/m²/year. Spartina net production was 25 % of its gross production and 86 % of total net production (Spartina plus benthic microalgae). These Spartina production values and ratios are similar to those observed in natural Spartina marshes. Average specific activities of plant tissues were 42.4 gmCi/g C for new leaves and 16.0 and 14.0 μCi/g C for stem bases and roots, respectively. The tissues are suitable for experimental studies of breakdown and utilization of Spartina by microbial heterotrophs and detritus consumers. The chamber could be used in conjunction with existing techniques for seed germination and seedling growth to produce uniformly labeled Spartina plants.     

Observations and experiments on regeneration in Planarians

Development Genes and Evolution -