Electrical Stimulation and its Effects on Indoleacetic Acid and Peroxidase Levels in Tomato Plants (Lycopersicon esculentum)

The effect of applied direct electrical currents (3–7µA) on the levels of indoleacetic acid (IAA) and peroxidasein tomato plants was determined. Six-week-old treated and controltomato plants were divided into four parts (petiole, leaf, root,and internode). The levels of IAA and peroxidase were higherin the treated tissues (leaf and petiole) compared to the controls.There was not a significant difference in peroxidase levelsin internodal tissue between treated and control plants; however,the peroxidase level in treated root tissue was lower than incontrol plants. It is suggested that small currents may alterthe levels of IAA and peroxidase in different plant tissues.     

Social Play in the American Black Bear: Its Similarity to Canid Social Play and an Examination of its Identifying Characteristics

Bears evolved from a canid stock at quite a recent date (earlyMiocene). Despite this recent origin, bcars show substantialmorphological, physiologicai, and ecological differences whencompared to modern day canids. However, the display behaviorsof Canidae and Ursidae have remained remarkably similar. Inthis paper, the motor patterns of black bear social play aredescribed in detail. Numerous similarities between canid andursid social play are pointed out. Agonistic displays commonto both families are also pointed out. These behavioral similaritiessupport the principle that social behavior, particularly displaybehavior, will frequently be conservative in its evolution ascompared to the evolution of morphology, anatomy, or ecologicaladaptations. Beach (1945) stressed the importance of identifying and testingthe general characteristics of play. A large number of characteristicshave been suggested as being diagnostic of play, but these characteristicshave received very little testing. Five characteristics of socialplay were tested in this study, and two were found to be onlypartially valid for black bear social play. Extensive testingof the general characteristics of play on as wide a range ofspecies as possible is definitely recommended for future research.     

PHYSICAL ASPECTS OF STERILIZING COTTON ARTICLES BY STEAM

SUMMARY: In this paper some of the physical processes occurring when cotton articles are sterilized in metal drums or bare packages in an autoclave are discussed, with special reference to the case where a good vacuum is drawn before the admission of steam. It is shown that under these conditions the heating will be quick, uniform, regular and reversible, and that no separate drying-off period should be needed. Calculation of the temperatures and moisture contents reached during the 'quasiequilibrium'period shows that the 'superheating'of the cotton is self-limiting, can never exceed a few degrees Centigrade, and will not give rise to serious weakening of the cotton. Calculation of the rate of irreversible penetration of moisture into the contents of the drum shows that this can easily be limited to the wrapping layer. Information is given on the 'heat-tendering'of cotton, and the advantages of using a good vacuum are summarized.     

Determination of Inositol in Inbred and Hybrid Corn (Zea mays) Seedlings

Four inbred (W_f9, Hy₂, B₁₀, and 38–11) plus three hybrid(W_f9 x 38.11, US13, and B₁₀ x Hy2) corn (Zea mays) seedlingstrains (minus seed coat and endosperm) were assayed for totaland free myoinositol content, using a mutant inositol-less straino Neurospora crassa. Over a 120-h germination period, it wasfound that the concentration of total myoinositol decreasedin both of the respective varieties. The inbred corn seedling strains, assayed in this study, appearto demonstrate a lower decrease in total myoinositol than dothe hybrids, over the same 120-h germination period. Concomitantly,the hybrid strains have a higher percentage increase in freemyoinositol than do the inbred varieties, over the same germinationtime period. The hybrid corn seedling strains appear to havea greater capacity to mediate the metabolism of total to freemyoinositol, during the early stages of germination, comparedto the inbred varieties.     

Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan

1. We sampled along a nearshore transect (10-m bathymetric contour) in Lake Michigan to determine diet, 24-h feeding periodicity, daily ration and food requirements of an invasive fish, the alewife, Alosa pseudoharengus , relative to zooplankton abundance and production. Our objective was to determine whether the alewife controls the abundance of two invasive, predatory cladocerans, Bythotrephes longimanus and Cercopagis pengoi .
2. Bosminidae was the most abundant prey taxon and Chydoridae, Leptodora , Chironomidae and Bythotrephes were the least abundant. Neither Bythotrephes nor Cercopagis were important prey for small alewives (≤100 mm). Bythotrephes was eaten by over 50% of large alewives (>100 mm) and accounted for 10–27% of the diet weight. Cercopagis was eaten by about 30% of the large alewives but only accounted 1% of the diet weight.
3. Food weight in stomachs was highest early in the night for small alewives and lowest at night for large alewives. Chironomidae and large Chydoridae were the preferred prey of small alewives. Bythotrephes and large Chydoridae were the preferred prey for large alewives.
4. Food requirements of alewife were much less than production for most prey taxa, although the consumption of Bythotrephes greatly exceeded production on both dates. Alewives consumed only 3% of Cercopagis production. High selectivity and food requirements of alewife for Bythotrephes , and low selectivity and food requirements for Cercopagis , probably explain the difference in abundance between these two invasive cladocerans at our nearshore site in Lake Michigan.     

Interactions in the uptake of amino acids, ammonium and nitrate ions in the Arctic salt-marsh grass, Puccinellia phryganodes

The uptake of amino acids and inorganic nitrogen by roots of Puccinellia phryganodes was examined to assess the potential contribution of soluble organic nitrogen to plant nitrogen uptake in Arctic coastal marshes, where free amino acids constitute a substantial fraction of the soil‐soluble N pool. Short‐term excised root uptake experiments were performed using tillers grown hydroponically under controlled conditions in the field. The percentage reductions in ammonium uptake at moderate salinity (150 mm NaCl) compared with uptake at low salinity (50 mm NaCl) were double those of glycine, but glycine uptake was more adversely affected than ammonium uptake by low temperatures. Glycine uptake was higher at pH 5·7 than at pH 7·0 or 8·2. The glycine uptake was up‐regulated in response to glycine, whereas ammonium uptake was up‐regulated in response to ammonium starvation. Nitrate uptake was strongly down‐regulated when tillers were grown on either ammonium or glycine. In contrast to N‐starved roots, which absorbed ammonium ions more rapidly than glycine, the roots grown on glycine, ammonium and nitrate and not N‐starved prior to uptake absorbed glycine as rapidly as ammonium and nitrate ions combined. Overall, the results indicate that amino acids are probably an important source of nitrogen for P. phryganodes in Arctic coastal marshes.