Growth,sporulation and toxin production byBacillus thuringiensis subsp.israelensis andB. sphaericus in media based on mustard-seed meal

Bacillus thuringiensis subsp.israelensis andB. sphaericus strains 2362 and 1593 were grown in media based on defatted mustard-seed meal (MSM). The meal contains 40% (w/w) protein, with glutamic acid and arginine as the major amino acids. The toxic potencies of the final bacterial powders towardsCulex pipens quinquefasciatus Say, compared with those of the respective international reference standards, were 46% forB. thuringiensis subsp.israelensis, 62% forB. sphaericus 2362 and 88% forB. sphaericus 1593 when 2% (w/v) MSM was used for growth. With 4% (w/v) MSM,B. thuringiensis subsp.israelensis grew better but had undetectable larvicidal activity, whereas theB. sphaericus strains not only grew better but gave a higher degree of sporulation and toxicity. The potencies ofB. sphaericus in medium with 4% MSM were comparable with those of international reference standards.The authors are with the Department of Life Sciences, University of Bombay, Bombay 400 098, India.     

一种免受乙醇干扰的GOD的酶电极

将酶电极应用于发酵糖的测定时。与糖共存的乙醇常常会影响测糖的准确性,通过对葡萄糖氧化酶(GOD)电极的研究,探讨了乙醇对测糖酶电极测定影响,进而研制出抗干扰的GOD酶电极,若是GOD电极的酶膜通过夹心法制备．在乙醇含量为0．1％(V／V)时·即产生显著的影响,使测定结果偏大4．3%,且乙醇的影响随浓度的升高而增大,若用尼龙网固定GOD膜,GOD电极在测定20mmol／L和5mm01／L左右的葡萄糖溶液时,含量高达9％的乙醇仍未对测定产生显著的影响．表现出良好的不受乙醇干扰的特性,并且,该尼龙网GOD电极具有良好的重复性、稳定的响应活性及较长的保存期．     

Roche Susceptibility Test (RST) medium,a defined formulation for susceptibility testing: I. Nutrient interaction and optimization studies

Roche Susceptibility Test (RST) Medium represents the most completely optimized and convenient fully defined medium described. It requires no post-autoclaving supplementation with vitamins, supports good growth of all common aerobic and anaerobic pathogens and may be used as a broth or agar gel on which the swarming of Proteus spp. is virtually eliminated. The broth as a superior buffering capacity to most complex media and an osmolality and pH close to those of human serum. RST is highly satisfactory for the susceptibility testing of commonly used antibiotics and meets the requirements of the National Committe for Clinical Laboratory Standards of the U.S.A. in almost every respect.     

Cultured hepatoma cells for the study of enzyme regulation: Induction of ornithine decarboxylase by insulin and asparagine

Summary The induction and decay of ornithine decarboxylase (ODC) by insulin and asparagine in cultures of H4-II-EC3 (H35) hepatoma cells was studied in a modified Waymouth medium in the presence of fetal bovine serum (FBS) and in serum-free media. The insulin response was enhanced by the presence of asparagine although the effect of asparagine was not so much on the initial increase as it was on a slowing of the decline after the maximum was reached at 6 to 8 h after the supplements were added together with fresh medium. In all cases the initial ODC activity was zero at zero time for addition of media and supplements, and, after reaching the maximum, activity declined to near zero by 24 h. Fetal bovine serum gave induction that followed a similar time course but was inferior to the combintion, of insulin plus asparagine and, in fact, FBS inhibited the latter response. Putrescine (the product formed from ornithine by ODC), at 10⁻⁵ M, markedly inhibited the induction of ODC by insulin or FBS, but the inhibition was less when asparagine was present. This work was supported in part by Grants CA-07175, CA-22484, and CA-17334 from the National Cancer Institute. D. P. G. is a Predoctoral Fellow at the Food Research Institute, supported by a fellowship from the Monsanto Fund and by NIH Grant R01-AI 15693 to Prof. Michael W. Pariza, Food Research Institute, University of Wisconsin, Madison.     

Gypsy moth cell lines divergent in viral susceptibility

Summary A series of cell lines unique in insect virus susceptibility pattern have been isolated from the ovaries of the gypsy moth (Lymantria dispar: Lepidoptera: Lymantriidae) on a synthetic medium with mammalian and avian serum supplementation. Growth curves showed the poorest growth occurring on peptone-based media with somewhat better growth on amino-acid-based media. The best growth was obtained with combined media. Serological study distinguished the present cell lines from one another and from cell lines derived from other insect species grown routinely in the same laboratory. Baculovirus susceptibility among the new lines varied from no response to a specific complete replication response upon challenge by the homologous (gypsy moth) nuclear polyhedrosis virus. This research was funded in part through a reimbursable agreement with the U.S. Forest Service.     

Physical conditions of propagation media and their influence on the rooting of cuttings

Summary The air content in three types of propagation media, Jiffy-7 and Jiffy-9 which are Sphagnum peat and Grodan which is rockwool, were investigated when they were held at moisture tensions of 0,6 and 12 cm measured from the base of the media. At 0 cm tension the air content (vol. %) was highest in Jiffy-9 and lowest in Jiffy-7. At 12 cm tension the air content was higher in Grodan than in Jiffy-9 and Jiffy-7. Oxygen diffusion coefficients (ODC) and oxygen diffusion rates (ODR) were measured at the different air contents. At air contents below 20 vol. % ODC was about the same for Jiffy-9 and Grodan but at air contents above 20 vol.% it was larger for Jiffy-9 than for Grodan. The oxygen diffusion rate was measured at 0, 4 and 8 cm moisture tension. At all tensions it was approximately 20% higher in Jiffy-9 than in Grodan and Jiffy-7. The ODR in Jiffy-7 and Grodan were affected equally at the same tension, although Grodan contained more air. Report no 253     

Effects of glutathione and of cysteine on intestinal absorption of selenium from selenite

The influence of glutathione (1 mmol/L) (GSH) on in vitro mucosal uptake and in vivo absorption of⁷⁵Se-labeled selenite (10 μmol/L) was investigated in rat jejunum. For comparison, the effect ofl-cysteine (1 mmol/L) on in vivo absorption of⁷⁵Se-labeled selenite was also studied. In the in vitro, uptake experiments, only the mucosal surface was exposed to the incubation medium for 3 min. For the in vivo experiments, a luminal perfusion technique was employed. GSH inhibited in vitro mucosal Se uptake, whereas absorption in vivo was stimulated by GSH.l-Cysteine also stimulated in vivo Se absorption, confirming former in vitro mucosal uptake experiments. Thus, unlikel-cysteine, GSH affected in vitro and in vivo absorption of Se from selenite differently. Enzymatic cleavage of products of the reaction of selenite with GSH occuring more efficiently under in vivo than in vitro conditions may be a prerequisite for the stimulatory effect of GSH on Se absorption. This apparently does not apply to the stimulatory effect of cysteine. Since, GSH occurs in the intestinal lumen under physiological conditions, it may contribute to the high bioavailability of Se from selenite.     

Stimulation of mucosal uptake of selenium from selenite by some thiols at various sites of rat intestine

The influence of several thiols (conc. 1 mmol/L) on mucosal uptake of⁷⁵Se from⁷⁵Se-labeled selenite (conc. 10 μmol/L) across the brush border of rat jejunum and cecum was investigated in vitro using a short-term uptake technique.l-Cysteine (l-Cys) stimulated⁷⁵Se uptake in the mid- and distal jejunum and cecum, but not in the proximal jejunum. The effect was maximal in the distal jejunum.d-Cys was less effective in the jejunum and similarly effective in the cecum.l-Leucine (l-Leu) andl-glutamic acid significantly reduced the stimulatory effect ofl-Cys on Se uptake in the distal jejunum, whereas the respective effect ofd-Cys was not diminished byl-Leu. Cysteamine stimulated mucosal⁷⁵Se uptake at all intestinal sites tested, whereas the effect of mercaptopyruvate was restricted to the distal jejunum. Thioglycolate also enhanced⁷⁵Se uptake in the distal jejunum. The stimulatory effects ofl-Cys, mercaptopyruvate, and thiologlycolate were Na⁺-dependent, whereas the effect of cysteamine also occurred in the absence of Na⁺. Mercaptosuccinate,d-penicillamine, ergothioneine, and thiosulfate did not enhance mucosa⁷⁵Se uptake. It is concluded from these findings that the reaction of some thiols with selenite results in Se compounds that are rapidly absorbed by the intestinal epithelium through various Na⁺-dependent and Na⁺-independent, mechanisms. The high bioavailability of Se from selenite found by others might thus be the result of the presence of thiols in the gastrointestinal tract.     

An examination and correction of plant tissue culture basal medium formulations

The inorganic formulations of fourteen common plant tissue culture basal media were examined from the primary literature. Inaccuracies and errors were found for molecular formulae, chemical hydrations, and molar equivalences for iron/EDTA complexation. A comparison with published basal medium formulations from six commercial suppliers uncovered additional inaccuracies, modifications, and errors, thereby emphasizing the need for investigators to examine and describe medium formulations precisely in future publications.     

Impact of the field slug Deroceras reticulatum on establishment of ryegrass and white clover in mixed swards

The relationship between numbers of Deroceras reticulatum and the establishment of ryegrass cv. Melle and white clover cv. Milkanova was studied on a mini-plot experiment. Assessments 12 and 33 days after sowing showed that Deroceras reticulatum had a proportionally greater impact on survival and growth of clover than on ryegrass. Slugs had no apparent effect on numbers or growth of three species of broad-leaved weeds (Senecio vulgaris, Cardamine hirsuta and Epilobium sp.) which occurred in the field experiment. In pot experiments where seedlings of ryegrass together with one of three clover cultivars, with or without chickweed (Stellaria media), were exposed to Deroceras reticulatum, seedlings of white clover cv. Aran were less affected by slug grazing than cvs S184 or Milkanova. The presence of different clover cultivars did not significantly influence the impact of slugs on growth of ryegrass or chickweed, nor did the presence or absence of chickweed influence the effect of slugs on ryegrass and clover seedlings. Slugs had less impact on the growth of chickweed than on ryegrass or clover. Thus slug grazing would make clover less able to compete with chickweed as well as the other weeds found in the mini-plot experiment.