Requirement of standardized ileal digestible valine to lysine ratio for 8- to 14-kg pigs

The objective was to define the Val requirement for weaned piglets in the context of reducing the dietary protein content. A dose–response experiment was conducted to estimate the standardized ileal digestible (SID) Val to Lys ratio required to support the optimum growth of post-weaned piglets. In this study, 96 pigs weighing 8 kg were allotted to one of six dietary treatments (16 pigs for each dietary treatment) and were housed individually. Diets were formulated to provide 0.58, 0.62, 0.66, 0.70, 0.74 and 0.78 SID Val : Lys by adding graded levels of crystallinel-Val to the 0.58 SID Val : Lys diet. Lysine was sub-limiting and supplied 90% of the recommendation (10.95 g SID Lys/kg equal to 11.8 g/kg total Lys). Average daily feed intake (ADFI), average daily gain (ADG) and gain to feed ratio (G : F) were determined during a 14-day period ofad libitum feeding. Blood and urine samples were taken at the end of each week (day 7 and 14 of the experiment) 3 h after feeding the experimental diets. The maximum ADFI and ADG were obtained in pigs fed the 0.78 SID Val : Lys diet; it was not different from the results of pigs fed 0.70 SID Val : Lys diet. The highest G : F was obtained in pigs fed 0.70 SID Val : Lys. The plasma concentration of Val increased linearly (P<0.001) as the dietary SID Val : Lys increased. The increasing dietary Val : Lys also resulted in a linear increase in Cys (P<0.001) and a quadratic increase in Arg (P=0.003), Lys (P=0.05) and Phe (P=0.009). The plasma Gly showed a quadratic decrease (P=0.05) as the dietary Val : Lys increased. Neither plasma nor urinary urea to creatinine ratio was affected by treatment. The minimum SID Val : Lys required to maximize ADFI, ADG and G : F was estimated at 0.67 SID Val : Lys by a broken-line model, and at 0.71 SID Val : Lys by a curvilinear plateau model. The Val deficiency caused a reduction in ADFI, and Val supplementation above the requirement did not impair animal performance. In conclusion, 0.70 SID Val : Lys is suggested as the Val requirement for 8 to 14 kg individually housed pigs.     

ENDURANCE EXERCISE TRAINING AND DIFERULOYL METHANE SUPPLEMENT: CHANGES IN NEUROTROPHIC FACTOR AND OXIDATIVE STRESS INDUCED BY LEAD IN RAT BRAIN

Lead is a highly neurotoxic agent that particularly affects the developing central nervous system. In the current study we investigated the neuroprotective effects of exercise training and/or diferuloyl methane (DM) supplement, which is known as curcumin, on lead acetate-induced neurotoxicity in the rat hippocampus. Sixty rats were randomly divided into six groups: 1) lead acetate, 2) DM supplement, 3) endurance training, 4) training+ DM supplement, 5) sham and 6) base. The rats in the training groups performed treadmill running consisting of 15 to 22 m · min^-1 for 25 to 64 min, 5 times a week for 8 weeks. All groups except sham received lead acetate (20 mg · kg^-1), whereas the sham group received DM solvent. In addition, the DM and training + DM groups received DM solution (30 mg · kg^-1) intraperitoneally. Chronic administration of lead acetate resulted in a significant increase in the malondialdehyde (MDA) in plasma, but not in the hippocampus. In addition, it led to significantly decreased brain-derived neurotrophic factor (BDNF) in the hippocampus and total antioxidant capacity (TAC) levels, as compared to the sham group. Treadmill running, DM supplementation, or both resulted in a significant decrease in MDA levels and significantly increased BDNF and TAC levels, as compared to the lead acetate group. These results provide a rationale for an inhibitory role of DM supplement and regular exercise in the attenuation of lead-induced neurotoxicity.     

Effects of nutritional stress during different developmental periods on song and the hypothalamic–pituitary–adrenal axis in zebra finches

In songbirds, developmental stress affects song learning and production. Altered hypothalamic–pituitary–adrenal (HPA) axis function resulting in elevated corticosterone (CORT) may contribute to this effect. We examined whether developmental conditions affected the association between adult song and HPA axis function, and whether nutritional stress before and after nutritional independence has distinct effects on song learning and/or vocal performance. Zebra finches (Taeniopygia guttata) were raised in consistently high (HH) or low (LL) food conditions until post-hatch day (PHD) 62, or were switched from high to low conditions (HL) or vice versa (LH) at PHD 34. Song was recorded in adulthood. We assessed the response of CORT to handling during development and to dexamethasone (DEX) and adrenocorticotropic hormone (ACTH) challenges during adulthood. Song learning and vocal performance were not affected by nutritional stress at either developmental stage. Nutritional stress elevated baseline CORT during development. Nutritional stress also increased rate of CORT secretion in birds that experienced stress only in the juvenile phase (HL group). Birds in the LL group had lower CORT levels after injection of ACTH compared to the other groups, however there was no effect of nutritional stress on the response to DEX. Thus, our findings indicate that developmental stress can affect HPA function without concurrently affecting song.     

Impact of a diamond mining industry on metabolites in Larix gmelinii

We studied the technogenic impact of a diamond mining company on the content of metabolites in the needles of Larix gmelinii (Rupr.) Kuzen. The samples of larch needles were collected in the Arctic zone in the restricted area where the diamond mining company works. The studied sites are located in Anabarsky district of Yakutia (Russia). An activity of the diamond mining company did not have a significant impact on the characteristics of the forest stand. But at the same time, near the sorting and enriching plants of the diamond mining company, the concentrations of Si, Ca, Fe, Mn, Al, Na, Sr, Ba, Zn, Pb, Ni, V were higher in the needles of L. gmelinii than those in the control zone. The activity of the diamond mining industry resulted in: intensification of the lipid peroxidation process, growth of a content of resin acids and amino acids, activation of cellular respiration processes, thickening of the cell wall, and a decline in the concentration of unsaturated fatty acids and antioxidants. We have concluded that some observable biochemical changes occur in the trees as a resulting effect of adaptive processes to the technogenic load despite the absence of significant changes in the forest stand.     

Chlorophyll fluorescence parameters of three Mediterranean shrubs in a summer-autumn period in central Portugal

The photosynthetic performance of Cistus crispus, Centaurea africana and Thymus villosus, three shrubs of the Mediterranean-type maquis vegetation of Central Portugal, were studied between July and December 2003 by means of in vivo chlorophyll a fluorescence measurements. In C. africana total leaf decay occurred between August and October, in T. villosus no clear pattern of variation of the basal fluorescence (F_o) was observed, and in C. crispus an increase of this parameter was observed in late autumn. In all species, the limitation to photosynthesis by photoinhibition and the contribution of non-reversible processes to total photoinhibition were more pronounced in the summer than in the autumn. However, a pronounced decrease of the effective quantum yield of photosystem 2 (Φ_PS2) was found in late autumn, probably due to a decrease of the carboxylation efficiency of the Calvin-Benson cycle, which was also supported by a parallel decrease of the photochemical quenching coefficient (qP).     

A novel cyclic opioid peptide analog showing high preference for mu-receptors

The side-chain to side-chain cyclized opioid peptide analogs H-Tyr-D-Orn-Phe-Asp-NH2 (I) and H-Tyr-D-Lys-Phe-Glu-NH2 (II) were synthesized and tested in the guinea pig ileum and mouse vas deferens assays and in binding assays based on displacement of mu- and delta-opioid receptor-selective radioligands from rat brain membranes. The more rigid cyclic analog I containing a 13-membered ring structure showed very high preference for mu-receptors over delta-receptors, whereas the more flexible cyclic peptide II (15-membered ring) was non-selective. These results indicate that variation in the degree of conformational restriction of opioid peptides can produce drastic shifts in their receptor selectivity profile. Because of its high mu-receptor selectivity and rigidity cyclic analog I will be useful for determining the conformational requirements of mu-opioid receptors.     

Performance of the isolated and perfused working heart of the teleostConger conger: study of the inotropic effect of prostacyclin

Summary An in vitro preparation of the heart of the teleostConger conger, isolated without the pericardium, was set up. The procedure allowed subambient pressures to develop in the perfusion chamber during contraction, mimicking the in vivo situation with the pericardium intact. The ventricle produced a cardiac output of about 15 ml·min^-1·kg wet body weight^-1 at subambient input pressure, and was able to double the stroke work with an increase of preload up to about 0.2 kPa. Using this preparation it was found that prostacyclin has a positive inotropic effect on the atrium and ventricle, but it does not affect the heart rate. Semilogarithmic doseresponse curves of prostacyclin on the atrium are reported, showing a threshold concentration of about 10^-9 M. The isolated and perfusedConger conger heart provides a useful model for a detailed analysis of the action of prostacyclin on myocardial contractility.     

Quantitative distribution of calcitonin gene-related peptide in the rat central nervous system

Using an antiserum directed against human calcitonin gene-related peptide (hCGRP), which fully cross reacts with rat CGRP, a sensitive radioimmunoassay was developed. The antiserum was characterized by displacement curve characteristics and high performance liquid chromatography. The assay was applied to rat brain tissue and the concentration of CGRP for 48 microdissected brain areas is presented. Highest levels (1000–4500 fmol/mg protein) were found in the central amygdaloid, caudate putamen, and spinal trigeminal nerve nucleus and tract, substantia gelatinosa, and the dorsal horn of the spinal cord. Moderate levels (200–600 fmol/mg protein) were found in the bed nucleus of the stria terminalis, the subfornical organ, the paraventricular, arcuate, dorsomedial, dorsal parabrachial, ambiguus and tractus solitarii nuclei and in the median eminence. These results coincide with those previously obtained by immunohistochemistry. The widespread distribution in the brain suggests involvement of CGRP in a variety of behavioral functions.