Effect of host switching on performance of mass‐reared Trichogramma minutum

The effect of host switching on parasitism by Trichogramma minutum Riley (Hymenoptera: Trichogrammatidae) (TM) was examined for parasitoids attacking a factitious host, the Mediterranean flour moth, Ephestia kuehniella Zell. (Lepidoptera: Pyralidae) (MFM), and a natural host, the eastern spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) (SBW). Parasitoids that were switched from rearing on the natural host to rearing on the factitious host had lower realized fecundities on both MFM and SBW eggs than a control line that was maintained continuously on the natural rearing host, SBW eggs. Conversely, T. minutum reared on the factitious host and switched to rearing on the natural host showed greater realized fecundities. This increase in realized fecundity was lost in the first generation after switching parasitoids back to the factitious rearing host. T. minutum that were maintained on the natural rearing host (SBW eggs) showed more variation in realized fecundity and host acceptance of both MFM and SBW eggs, than parasitoids that were reared on MFM eggs.     

The potlatch

Vincent Corrigan, anthropologist and novelist, is a key figure in the Irish Cultural Revivalist Movement.     

Excision of mutagenic replication-blocking lesions suppresses cancer but promotes cytotoxicity and lethality in nitrosamine-exposed mice

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Astringent Subqualities in Acids

Astringency, astringent subqualities (drying, roughing and puckering)and sourness were compared among six acids: hydrochloric, lactic,citric, acetic, fumaric and malic acids. The attribute profilesof organic acids were similar to each other but different fromhydrochloric acid, the only inorganic acid, which was the mostastringent and the least sour. In a second experiment, two inorganicacids (hydrochloric and phosphoric) and two organic acids (citricand malic) were tested at three concentration levels. At approximatelyequal levels of overall sensory impact, the inorganic acidswere alike in astringency and sourness, receiving higher ratingsfor roughing and drying, and lower ratings for sourness thanthe organic acids. Interactions with concentration (differencesin psychophysical functions) for the subquality of drying werenoted, in addition to the differences in the astringent subqualitiesof roughing and drying seen across acids in both experiments.The higher level of astringency for inorganic acids suggeststhat the current model for tannin binding to salivary proteinsas an explanation of astringency needs to be extended to includea direct pH-dependent effect. Chem. Senses 20: 593–600,1995     

Effect of zinc on cadmium influx and toxicity in cultured CHO cells

Addition of zinc lowers the toxicity level of cadmium in cultured CHO cells. Cell survival and protein synthesis were used to measure the cellular toxicity of cadmium.¹⁰⁹Cd was used to measure cadmium uptake by the cells. The results suggest that these class IIB transition metals, zinc and cadmium, share a common transport mechanism. Thus, the antagonism appears to involve a reduction in the influx of cadmium due to the presence of zinc.     

Cellular uptake of cadmium and zinc

CHO mutants, resistant to over 100-fold of a normally toxic level of extracellular cadmium have been used to examine the mutually antagonistic effect of Cd and Zn on their uptake. Cadmium uptake in these mutants is only 7–10% that of the parental cells. Zinc uptake in these mutants is equal to or greater than that in the wild-type cells. Results of kinetic studies on uptake indicated that the two metals interact by competitive inhibition. TheK _m andK _i values for Cd and/or Zn were different in some of the mutants and indicate multiple carriers may be involved in the transport of these metals. The reduction in Cd uptake and concomitant increase in Zn uptake contribute to the increased Cd resistance in these mutants.