FIBER TYPES DISTRIBUTION IN THE DIGASTRIC MUSCLE OF TUFTED CAPUCHIN MONKEY (CEBUS-APELLA)

Fiber types distribution in the diagastric muscle of tufted capuchin monkey was studied by means of NADH-TR, myosin-ATPase, after alkaline and acid preincubations and SDH histochemical reactions. Three different types of fibers were found presenting an equal distribution. The percentage and types of fibers were as follow: 18.2 % SO (Slow Oxydative), 38.4 % FOG (Fast Oxydative Glycolytic) and 43.4 % FG (Fast Glycolytic). FG fibers revealed the largest area. The relatively high concentration of fast twitch (81.2 %) seems to indicate this muscle is involved with the acceleration and fast speed of jaw movements. Aerobic metabolism represented by SO + FOG fibers (56.6 %) suggests that this muscle possesses an additional role than that related to the lowering of the jaw.

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.

An investigation of cadmium(II) and nickel(II) adsorption by chitin graft covolymer

Chitin hydrogels of poly(vinylpyrrolidone) (VP) were prepared by means of the hydrogen peroxide graft copolymerization process. The effect of the VP grafted chain on water diffusion through the biopolymer was studied. Fourier transform infrared spectra of the VP-g-Ch showed an increase in the intensities of the hydroxyl and carbonyl stretching bands indicating a reduction in the hydrogen bonding of chitin. An investigation was undertaken regarding the adsorption of nickel(II) and cadmium(II) ions from aqueous solutions by the VP grafted chitin and the effects of the grafting degree on the Cd2+ and Ni2+ sorption were studied. The Cd2+ and Ni2+ adsorption equilibrium data correlate well with the Freundlich equation. The results indicate that the Ch-g-VP graft copolymer under investigation is a potentially powerful chelating material that can be employed for Ni2+ and Cd2+ ion removal from wastewater effluents. (C) 2004 Wiley Periodicals, Inc.

Phenological aspects of Syngonanthus elegans (Bong.) Ruhl. (Eriocaulaceae) from Serra do Cipo - MG. Brazil

S. elegans (Eriocaulaceae) is known in Brazil as star flower and is used economically for ornamental purposes. The fact that there is no control over its collection, brings about great damage to its population. Thus the importance of phenologic data for the conservation of the species. This paper reports the marking of 60 individuals in three different phases of development and the collection of monthly data about their phenology. S. elegans is a perennial plant with a rhizomatous stem that characterizes its vegetative growth. The pubescent leaves present in plants can prevent heat loss and their pigments can raise the ultra-violet radiation absorption. The young leaves present in plants during the begining of the dry season use rhizome reserves. Hydric scarcity may be the main reason for the mortality of the species. Vegetative growth and sexual reproduction are very important for the population's survival.,The blooming period in S. elegans occurs from om February to July and the dispersal of seeds occurs from August to December.

Effects of cardiomyopathic mutations on the biochemical and biophysical properties of the human alpha-tropomyosin

Mutations in the protein alpha-tropomyosin (Tm) can cause a disease known as familial hypertrophic cardiomyopathy. In order to understand how such mutations lead to protein dysfunction, three point mutations were introduced into cDNA encoding the human skeletal tropomyosin, and the recombinant Tms were produced at high levels in the yeast Pichia pastoris. Two mutations (A63V and K70T) were located in the N-terminal region of Tm and one (E180G) was located close to the calcium-dependent troponin T binding domain. The functional and structural properties of the mutant Tms were compared to those of the wild type protein. None of the mutations altered the head-to-tail polymerization, although slightly higher actin binding was observed in the mutant Tm K70T, as demonstrated in a cosedimentation assay. The mutations also did not change the cooperativity of the thin filament activation by increasing the concentrations of Ca2+. However, in the absence of troponin, all mutant Tms were less effective than the wild type in regulating the actomyosin subfragment 1 Mg2+ ATPase activity. Circular dichroism spectroscopy revealed no differences in the secondary structure of the Tms. However, the thermally induced unfolding, as monitored by circular dichroism or differential scanning calorimetry, demonstrated that the mutants were less stable than the wild type. These results indicate that the main effect of the mutations is related to the overall stability of Tm as a whole, and that the mutations have only minor effects on the cooperative interactions among proteins that constitute the thin filament.

HISTOCHEMICAL RESPONSES of RATS EXERCISED IN TWO WEEKLY FREQUENCIES and INGESTING STANDARD OR HYPERCALORIC DIET

This study investigated if overfed rats present morphological and histochemical muscle adaptation similar to normally fed, both submitted to two different weekly frequencies of training. Thirty male Wistar rats were fed either with standard chow (SCO) or with hypercaloric diet (HCO). They were subdivided into six subgroups: sedentary (SCO and HCO), trained twice/week (SC2 and HC2) and trained five times/week (SC5 and HC5). The trained groups swam 60 min/day, during 10 weeks. Twenty four hours after the last training, samples of Gastrocnemius were excised and stained with HE, NADH-TR and m-ATPase, and the capillary density was calculated. Total heart mass (HM) and the mass of atrium (AM), left (LV) and right (RV) ventricles were excised and weighted. The comparisons were made by ANOVA and by Covariance analysis, adjusting the variables by body weight. The results showed that the HCO achieved higher BM, however, absolute HM did not differ post training. Irrespective of the diet, rats that were trained twice a week presented significantly greater increase in the AM. In general, the SC5 and HC5 groups showed higher HM, LV, RV, proportion of oxidative fibres and capillary density, compared to the sedentary and twice week trained groups. A higher proportion of injuries (splitting) was noted in the HC2 and HC5 compared to SC2 and SC5. These results indicate that the frequency of training influenced the skeletal and heart adaptation and larger changes were observed in the 5x/week group, which ingested the standard diet. The 5x/week training groups also presented large amount of muscle fibres damage.

Comparative effects of lantadene A and its reduced metabolite on mitochondrial bioenergetics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Crescimento de mudas micropropagadas da bananeira cv. Nanicão, em diferentes substratos e fontes de fertilizante

With the objective of evaluating the effect of different substrates combined with fertilizers in the growth of micropropagated seedlings of Cavendish banana (Musa spp. AAA), ail experiment was conducted in a randomized block design, in a 5 x 3 factorial scheme, with four repetitions. The substrates used were: S1 - subsoil land + carbonized rice hull + Rendmax Floreira (R); S2 - subsoil land + carbonized rice hull + Organifol (R); S3 - subsoil land + carbonized rice hull + Organifol (R) 9% SiO; S4 - Technes Vivatto (R); S5 - thick sand + carbonized rice hull + Rendmax Floreira (R). The fertilizer sources were: SA - without fertilizer; LL - slow-release fertilizer - Osmocote (R) 3M 14-14-14 (5.0 kg m(-3)) inixed in the substrate; and LN - normal-release fertilizer, 14-14-14 (7.5 g seedling(-1)) applied in covering. The height, collar diameter, leaf number, leaf area and dry matter were determined. Based on the differences of growth, substrates S 1, S2, S3 and S4 can be used with fertilizer 14-14-14, with slow (5.0 kg m(-3)) or normal (7.5 g seedling(-1)) release of nutrients.

Effect of renoguanylin on hydrogen/bicarbonate ion transport in rat renal tubules

Renoguanylin (REN) is a recently described member of the guanylin family, which was first isolated from eels and is expressed in intestinal and specially kidney tissues. In the present work we evaluate the effects of REN on the mechanisms of hydrogen transport in rat renal tubules by the stationary microperfusion method. We evaluated the effect of 1 mu M and 10 mu M of renoguanylin (REN) on the reabsorption of bicarbonate in proximal and distal segments and found that there was a significant reduction in bicarbonate reabsorption. In proximal segments, REN promoted a significant effect at both 1 and 10 mu M concentrations. Comparing control and REN concentration of 1 mu M, JHCO(3)(-) . nmol cm(-2) s(-1) -1,76 +/- 0.11(control) x 1,29 +/- 0,08(REN) 10 mu m: P<0.05, was obtained. In distal segments the effect of both concentrations of REN was also effective, being significant e.g. at a concentration of 1 mu M (JHCO(3)(-), nmol cm(-2) s(-1) -0.80 +/- 0.07(control) x 0.60 +/- 0.06(REN) 1 mu m; P<0.05), although at a lower level than in the proximal tubule. Our results suggest that the action of REN on hydrogen transport involves the inhibition of Na(+)/H(+) exchanger and H(+)-ATPase in the luminal membrane of the perfused tubules by a PKG dependent pathway. (c) 2009 Elsevier B.V. All rights reserved.

Acute exposure of a glyphosate-based herbicide affects the gills and liver of the Neotropical fish, Piaractus mesopotamicus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Abamectin affects the bioenergetics of liver mitochondria: A potential mechanism of hepatotoxicity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The Effects of N Helix Deletion and Mutant F29W on the Ca2+ Binding and Functional Properties of Chicken Skeletal Muscle Troponin C

To assess the structural and functional significance of the N helix (residues 3-13) of avian recombinant troponin C (rTnC), we have constructed NHdel, in which residues 1-11 have been deleted, both in rTnC and in the spectral probe mutant F29W (Pearlstone, J. R., Borgford, T., Chandra, M., Oikawa, K., Kay, C. M., Herzberg, O., Moult, J., Herklotz, A., Reinach, F. C., and Smillie, L.B. (1992) Biochemistry 31, 6545-6553). Comparison of the far- and near-UV CD spectra (±Ca2+) of F29W and F29W/ NHdel and titration of the Ca2+-induced ellipticity and fluorescence changes indicates that the deletion has little effect on the global fold of the molecule but reduces the Ca2+ affinity of the N domain, but not the C domain, by 1.6-1.8-fold. Comparisons of the mutants NHdel, F29W, and F29W/NHdel with rTnC have been made using several functional assays. In reconstituted troponin-tropomyosin actomyosin subfragment 1 and myofibrillar ATPase systems, both F29W and NHdel have significantly reduced Ca2+-activated enzymic activities. These effects are cumulative in the double mutant F29W/ NHdel. On the other hand, maximal isometric tension development in Ca2+-activated reconstituted skinned fibers is not affected with F29W and NHdel, although the Ca2+ sensitivity of NHdel in this system is markedly reduced. We conclude that both mutations, NHdel and F29W, are functionally deleterious, possibly affecting interactions of the N domain with troponin I and/or T.