Effects of bud phenology and foliage chemistry of balsam fir and white spruce trees on the efficacy of Bacillus thuringiensis against the spruce budworm, Choristoneura fumiferana

Abstract 1 Efficacy of commercial formulations of Bacillus thuringiensis ssp. kurstaki (Btk) against spruce budworm Choristoneura fumiferana was investigated in mixed balsam fir‐white spruce stands. Btk treatments were scheduled to coincide with early flaring of balsam fir shoots, and later with flaring of white spruce shoots. Btk efficacy on the two host trees was compared and examined according to the foliar content of nutrients and allelochemicals and the insect developmental stage at the time of spray. 2 Larvae fed white spruce foliage were less vulnerable to Btk ingestion than larvae fed balsam fir foliage. Higher larval survival on white spruce, observed 10 days after spray, was related to higher foliage content in tannins and a lower N/tannins ratio, which might have induced inactivation of Btk toxins. 3 Larval mortality due to Btk did not depend on spruce budworm larval age. 4 Foliage protection of both host trees was similar in plots treated with Btk: larval mortality due to Btk treatment reduced insect grazing pressure on balsam fir trees; meanwhile, suitability of white spruce foliage seemed to decrease very rapidly, which induced high larval mortality among spruce budworm fed on white spruce trees. Nevertheless, following Btk sprays, 50% more foliage remained on white spruce than on balsam fir trees, because of the higher white spruce foliage production. 5 Both spray timings achieved similar protection of white spruce trees, but Btk treatments had to be applied as early as possible (i.e. during the flaring of balsam fir shoots to optimally protect balsam fir trees in mixed balsam fir‐white spruce stands).     

Effect of bacterial lipopolysaccharide pyrogenal on the development of the Syrian hamster embryo

Pyrogenal is injected to female hamsters (Mesocricetus auratus) at various time of pregnancy twice, with a 24 hour's interval: at first 100 or 50, and then--50 or 25 minimal pyrogenic doses. The embryos are examined on the 15th day of the intrauterine development by means of main teratologic methods. Pyrogenal injected on the 9th--10th day of the embryonal development produces hydrocephaly, micrognathia, retardation in development, hemorrhagic syndrome. Pyrogenal injected during some other time of pregnancy produces hemolysis of erythrocytes. This is proved by presence of hemosiderin in the foetal liver.     

KINETICS OF THE INNER ENAMEL EPITHELIUM IN THE ADULT RAT INCISOR DURING ACCELERATED ERUPTION

Inner enamel epithelial (IEE) cell production was compared in accelerated and normal eruption (control). Each group consisting of thirty rats received 1 μCi/g tritiated thymidine. The animals were sacrificed at short time intervals up to 14 hr after injection. The excised incisors were cut mid-sagittally and processed autoradiographically.
The fast growing incisor produces twice as many cells as the control. Increased cell production is achieved in two ways: proliferative pool expansion (by 25.5%) and generation time ( t _c) shortening to 16 hr ( t _c= 23 hr in the control). Generation time shortening resulted mainly from a diminution in t _g1= 8.6 hr ( t _g1= 14.1 hr in the control) and t _s which equaled 5.5 hr ( t _s= 7 hr in control). Mitotic times which equaled 0.4 hr and t _g2, 1.5 hr were identical in both groups.
The eruption/IEE cell production ratio equals 1.1 in both groups.     

Sucrose Phosphate Synthase, Sucrose Synthase, and Invertase Activities in Developing Fruit of Lycopersicon esculentum Mill. and the Sucrose Accumulating Lycopersicon hirsutum Humb. and Bonpl

The green-fruited Lycopersicon hirsutum Humb. and Bonpl. accumulated sucrose to concentrations of about 118 micromoles per gram fresh weight during the final stages of development. In comparison, Lycopersicon esculentum Mill. cultivars contained less than 15 micromoles per gram fresh weight of sucrose at the ripe stage. Glucose and fructose levels remained relatively constant throughout development in L. hirsutum at 22 to 50 micromoles per gram fresh weight each. Starch content was low even at early stages of development, and declined further with development. Soluble acid invertase (EC 3.2. 1.26) activity declined concomitant with the rise in sucrose content. Acid invertase activity, which was solubilized in 1 molar NaCl (presumably cell-wall bound), remained constant throughout development (about 3 micromoles of reducing sugars (per gram fresh weight) per hour. Sucrose phosphate synthase (EC 2.4.1.14) activity was present at about 5 micromoles of sucrose (per gram fresh weight) per hour even at early stages of development, and increased sharply to about 40 micromoles of sucrose (per gram fresh weight) per hour at the final stages of development studied, parallel to the rise in sucrose content. In comparison, sucrose phosphate synthase activity in L. esculentum remained low throughout development. The possible roles of the sucrose metabolizing enzymes in determining sucrose accumulation are discussed.     

A new device for measuring diffusional restrictions and modelling substrate inhibition in a starch-glucoamylase system

An experimental device that quantifies the diffusional properties of polysaccharides solution, in a simple and reproducible way, and an equation relating these properties to solute concentration, is proposed. Using this model to analyse the kinetic profile of the hydrolysis of starch with glucoamylase, is substrate inhibition completely reduced to phenomena that depends on the reological properties of the reacting mixture. The experimental device and kinetic model can be applied to contrast hypothetical substrate inhibitions in any enzymatic system.     

Reliability difference between spectral and entropic measures of erector spinae muscle fatigability

This study investigated back muscle fatigability of the erector spinae (ES) muscles during submaximal contractions with the use of surface electromyography (sEMG). It was important to confirm the reliability of measurements for characterizing neuromuscular alterations by establishing the difference between the Shannon (information) entropy and the power spectrum analysis in subjects with low back pain (LBP). The data was collected on two different days, one week apart, and the between-days reliability of these measures was examined. Thirty-two gender-matched subjects completed the modified Sorenson test; 16 of the subjects were female while 16 were male. The entropy of the sEMG signal was more reliable than either the median frequency (MF) or the slope of the MF. The intraclass correlation coefficient (ICC) was higher for the entropy than for the MF slope. The ICC values of entropy for between-day measurements were higher (0.82–0.85) than MF (0.54–0.64) and MF slope (0.26–0.30). The standard errors of measurement (SEM) values for entropy were lower (0.04–0.05) than MF (3.10–3.60) and MF slope (0.03–0.04). The Pearson correlation coefficients of the entropy were significantly higher (0.75–0.77) than those of the MF (0.38–0.47) and the MF slope (0.15–0.18). Therefore, the results of this study indicated that the entropy analysis could provide a reliable measure of muscle fatigability.     

Acute effects of glyphosate herbicide on metabolic and enzymatic parameters of silver catfish (Rhamdia quelen)

Silver catfish (Rhamdia quelen; Teleostei) were exposed to commercial formulation Roundup, a glyphosate herbicide: 0 (control), 0.2 or 0.4 mg/L for 96 h. Fish exposed to glyphosate showed an increase in hepatic glycogen, but a reduction in muscle glycogen at both concentrations tested. Glucose decreased in liver and increased in muscle of fish at both herbicide concentrations. Glyphosate exposure increased lactate levels in liver and white muscle at both concentrations. Protein levels increased in liver and decreased in white muscle while levels of ammonia in both tissues increased in fish at both glyphosate concentrations. Specific AChE activity was reduced in brain after treatments, no changes were observed in muscle tissue. Catalase activity in liver did not change during of exposure. Fish exposed to glyphosate demonstrated increased TBARS production in muscle tissue at both concentrations tested. For both glyphosate concentrations tested brain showed a reduction of TBARS after 96 h of exposure. The present results showed that in 96 h, glyphosate changed AChE activity, metabolic parameters and TBARS production. The parameters measured can be used as herbicide toxicity indicators considering environmentally relevant concentration.