CONCERTED ACTION OF THE HIGH-AFFINITY CALCIUM-BINDING SITES IN SKELETAL-MUSCLE TROPONIN-C

Mutants of each of the four divalent cation binding sites of chicken skeletal muscle troponin C (TnC) were constructed using site directed mutagenesis to convert Asp to Ala at the first coordinating position in each site. With a view to evaluating the importance of site-site interactions both within and between the N- and C-terminal domains, in this study the mutants are examined for their ability to associate with other components of the troponin-tropomyosin regulatory complex and to regulate thin filaments. The functional effects of each mutation in reconstitution assays are largely confined to the domain in which it occurs, where the unmutated site is unable to compensate for the defect, Thus the mutants of sites I and II bind to the regulatory complex but are impaired in ability to regulate tension and actomyosin ATPase activity, whereas the mutants of sites III and IV regulate activity but are unable to remain bound to thin filaments unless Ca2+ is present. When all four sites are intact, free Mg2+ causes a 50-60-fold increase in TnC's affinity for the other components of the regulatory complex, allowing it to attach firmly to thin filaments. Calcium can replace Mg2+ at a concentration ratio of 1:5000, and at this ratio the Ca2 . TnC complex is more tightly bound to the filaments than the Mg2 . TnC form, In the C-terminal mutants, higher concentrations of Ca2+ (above tension threshold) are required to effect this transformation than in the recombinant wild-type protein, suggesting that the mutants reveal an attachment mediated by Ca2+ in the N-domain sites.

Ability of bacteriophages isolated from different sources to reduce Salmonella enterica serovar enteritidis in vitro and in vivo

Salmonella enterica serovar Enteritidis-lysing bacteriophages isolated from poultry or human sewage sources were used to reduce Salmonella Enteritidis in vitro and in experimentally infected chicks. Cocktails of 4 different bacteriophages obtained from commercial broiler houses (CB4O) and 45 bacteriophages from a municipal wastewater treatment plant (WT45O) were evaluated. In experiment 1, an in vitro crop assay was conducted with selected bacteriophage concentrations (105 to 101 pfu/mL) to determine ability to reduce Salmonella Enteritidis in the simulated crop environment. Following 2 h at 37 degrees C, CB40 or WT45O reduced Salmonella Enteritidis recovery by 1.5 or 5 log, respectively, as compared with control. However, CB40 did not affect total SE recovery after 6 h, whereas WT45O resulted in up to a 6-log reduction of Salmonella Enteritidis. In experiment 2, day-of-hatch chicks were challenged orally with 3 x 103 cfu /chick Salmonella Enteritidis and treated cloacally with 1 X 109 WT45O pfu/chick I h postchallenge. One hour later, chicks were treated or not with a commercially available probiotic (Floramax-B11). Both treatments significantly reduced Salmonella Enteritidis recovery from cecal tonsils at 24 h following vent lip application as compared with controls, but no additive effect was observed with the combination of bacteriophages and probiotic. In experiment 3, day-of-hatch chicks were challenged orally with 9 x 103 cfu/chick Salmonella Enteritidis and treated via oral gavage with I X 108 CB40 pfu/chick, 1.2 x 108 WT45O pfu/chick, or a combination of both, I h postchallenge. All treatments significantly reduced Salmonella Enteritidis recovered from cecal tonsils at 24 h as compared with untreated controls, but no significant differences were observed at 48 h following treatment. These data suggest that some bacteriophages can be efficacious in reducing SE colonization in poultry during a short period, but with the bacteriophages and methods presently tested, persistent reductions were not observed.

New chemical evidence for the ability to generate radical molecular ions of polyenes from ESI and HR-MALDI mass spectrometry

We report here new chemical evidence for the generation of radical molecular ions of compounds with a conjugated pi-system (polyene) in ESI and HR-MALDI mass spectrometry. The oxidation potential of the neutral polyenes was calculated by cyclic-voltammetry and the results compared with those previously published for other complex conjugated compounds that have also been shown to form M.+ in ESI-MS. This study clearly demonstrates the correlation between the oxidation potential and the formation of the M.+ for the polyenes studied.

Does spatial visualization ability improve after studying technical drawing?

Two studies were carried out to analyze whether learning technical drawing improves a person's ability for spatial visualization. Visualization and inductive reasoning tests were applied at the beginning and end of a course in technical drawing in samples of first year engineering students. In both studies it was observed that a moderate percentage of students improved their Visualization test execution. The improvement was similar in men and women. There was no improvement on the inductive reasoning test. The results support the conclusion that the spatial visualization ability can be improved with training.

Medicinal plants' hosting ability for nematode meloidogyne javanica and m. incognita

Baida, F.C., D.C. Santiago, L. H. I. Vidal, L. C. Baida, C. T. Stroze. 2011. Medicinal Plants' Hosting Ability for Nematode Suitability Meloidogyne incognita and M. javanica. Nematropica 41: 150-153.Medicinal plants can be attacked by pests, diseases and nematodes, which can compromise the quality and quantity of their healing properties and their yield. The aim of this study was to analyse the reaction of 15 medicinal plant species to the nematode Meloidogyne spp. The seedlings were produced by seed germination or cuttings under greenhouse conditions. A completely random experimental pattern of 15 treatments and 10 replications was chosen for the study. The seedlings were inoculated with approximately 5000 eggs + J(2)/plant 20 days after planting. Plant height and fresh and dry leaf weight, were measured 60 days after planting. The roots were collected, thoroughly washed and stained with Philoxine B and then processed to extract the eggs to determine the reproduction factor. For M. incognita the results showed that Chamomile was susceptible with RF = 1,64 making it a good host, and the other plants were resistant (RF < 1), and for M. javanica that all the plants showed resistance (RF < 1), Myrrh, Rue and Balsam demonstrating immunity (RF = 0).

Pressure evaluation of the antireflux ability of the rat ureterovesical junction

The bladder pressure necessary to cause vesicoureteral reflux (VUR) was measured in 16 female rats. Under general anesthesia, the ureters were exposed via an abdominal incission and a pressure catheter was placed near the uterovesical junction. Values of bladder distension and bladder pressure increase to cause VUR were obtained by injecting isotonic saline in one ureter until VUR in the opposite ureter was detected as a sudden pressure increase. After 5 min the same procedure was done on the contralateral side. This procedure was repeated eight times in each rat with a 15-min intermission. The bladder pressure at which VUR occurred was measured through a uretral catheter. Two groups were studied: G1, control, and G2, administration of intravenous metoclopramide (0.007 mg/100 g body weight) four times.