Effect of arginine supplementation on the morphology and function of intestinal epithelia and serum concentrations of amino acids in pigs exposed to heat stress

The exposure of pigs to heat stress (HS) appears to damage their intestinal epithelia, affecting the absorption of amino acids (AAs). Arg is involved in the restoration of intestinal epithelial cells but HS reduces Arg intake. The effect of dietary supplementation with Arg on the morphology of intestinal epithelia, AA transporter gene expression, and serum concentration (SC) of free AAs in HS pigs was analyzed. Twenty pigs (25.3 ± 2.4 kg body weight) were randomly assigned to two dietary treatments: Control (0.81% Arg), wheat–soybean meal diet supplemented with l-Lys, l-Thr, dl-Met, and l-Trp, and the experimental diet where 0.16% free l-Arg was supplemented to a similar Control diet (+Arg). All pigs were individually housed and exposed to HS, fed ad libitum with full access to water. The ambient temperature (AT), recorded at 15-min intervals during the 21-d trial, ranged on average from 29.6 to 39.4 °C within the same day. Blood samples were collected on day 18 at 1600 hours (AT peak); serum was separated by centrifugation. At the end of the trial, five pigs per treatment were sacrificed to collect samples of mucosa scratched from each small intestine segment. The expression of AA transporters in intestinal mucosa and the SC of AAs were analyzed. Villi height (VH) was higher (P < 0.01) in the duodenum, jejunum, and ileum but the crypt depth did not differ between the Control and the +Arg pigs. Supplementation of l-Arg increased the mRNA coding for the synthesis of the cationic AA transporter b^0,+ (P < 0.01) and the neutral AA transporter B⁰ (P < 0.05) in the duodenum by approximately 5-fold and 3-fold, respectively, but no effect on mRNA abundance was observed in the jejunum and ileum. The supplementation of l-Arg increased serum Arg, His, Met, Thr, Trp, and urea (P < 0.05) and also tended to increase Val (P < 0.10) but did not affect Ile, Lys, Leu, and Phe. These results indicate that supplementing 0.16% l-Arg to the Control diet may help to improve the function of the small intestine epithelium, by increasing the VH, the abundance of AA transporters, and the SC of most indispensable AAs in pigs exposed to HS conditions. However, the lack of effect of supplemental Arg on both Lys SC and weight gain of pigs suggests that increasing the Lys content in the +Arg diet might be needed to improve the performance of HS pigs.     

Chemical characterization of the essential oil from patchouli accessions harvested over four seasons

The genus Pogostemon of the Lamiaceae family includes several species known for their medicinal and aromatic properties. The species P. cablin is especially notable because the essential oil extracted from its leaves is internationally important and valuable, principally for the perfume and cosmetic industries. Because multiple factors can affect the chemical composition of the essential oil, the aim of this work was to evaluate the chemical variations in the essential oils of nine Pogostemon accessions harvested over four seasons. Two Pogostemon accessions (P. heyneanus, but received as P. cablin) and seven P. cablin accessions from different sources were evaluated. The transplants were planted in January 2008, and the harvests were conducted in May, August, and November 2008 and February 2009. The chemical composition of the essential oils was evaluated quantitatively and qualitatively. Patchoulol was the major compound from the four harvests of all of the P. cablin accessions. The principal compound from the accessions POG-001 and POG-006 was β-pinene. Two clusters were detected by multivariate analyses of the four harvests. Cluster I was formed by the accessions POG-001 and POG-006 (P. heyneanus), and Cluster II was formed by the accessions of P. cablin (POG-002, POG-014, POG-015, POG-016, POG-019, POG-021, and POG-022).     

Estimation of banana (Musa sp.) plant transpiration using a standard 20 cm pan in a greenhouse

An experiment was carried out in a naturally ventilated greenhouse to study the relationship between banana (Musa sp.) plant transpiration (Tr) measured with load cells, reference crop evapotranspiration (ET_o) calculated with five widely used models (i.e. the Priestley-Taylor, FAO radiation, Hargreaves, FAO Penman and FAO Penman-Monteith models) and pan evaporation (E_pan) measured with a standard Chinese 20 cm pan. Microclimatic conditions were measured inside the greenhouse. Results show that vapor pressure deficit and air temperature had good linear correlations to banana Tr with R² of 0.67 and 0.62, respectively. Among the five models tested, banana Tr and ET_o calculated with the FAO-Penman model yielded the highest determination coefficient (R² = 0.67), followed by the FAO-PM model (R²=0.63), the FAO radiation model (R²=0.52), the Hargreaves model (R²=0.49) and the Priestley-Taylor model (R²=0.47). Banana transpiration Tr vs. E_pan yielded an R² of 0.83, which is higher than the five models tested. In conclusion, the 20 cm pan can be useful for estimating banana Tr in greenhouses.     

The potential of a herbicide resistant maize technology for Striga control in Africa

Striga is an obligate parasitic weed that attacks cereal crops in sub-Saharan Africa. In Western Kenya, it has been identified by farmers as their major pest problem in maize. A new technology, consisting of coating seed of imidazolinone resistant (IR) maize varieties with the imidazolinone herbicide, imazapyr, has proven to be very effective in controlling Striga on farmer fields. To bring this technology to the farmer, a sustainable delivery system needs to be developed, preferably with substantial participation of the private sector. To help extension agents and seed companies to develop appropriate strategies, the potential for this technology was analyzed by combining different data sources into a Geographic Information System (GIS). Superimposing secondary data, field surveys, agricultural statistics and farmer surveys made it possible to clearly identify the Striga-prone areas in western Kenya. Results found that Striga affected a maize area of 246,000 ha annually, with a population of 6.4 million people and maize production of 580,000 tons, or 81 kg/person. Population density in this area is high at 359 people/km². A survey of 123 farmers revealed that 70% of them have Striga in their fields. A contingent valuation (CV) survey indicated that farmers would, on average, be willing to buy 3.67 kg of the IR-maize seed each at current seed prices, sufficient to sow 44% of their maize area. By extrapolation over the maize area in the zone, total potential demand for IR-maize seed is estimated at 2000–2700 tons annually. Similar calculations, but based on much less precise data and expert opinion rather than farmer surveys or trials, gives an estimate of the potential demand for IR-maize seed in Africa of 153,000 tons.     

Air-breathing behavior and physiological responses to hypoxia and air exposure in the air-breathing loricariid fish, Pterygoplichthys anisitsi

Hypoxic water and episodic air exposure are potentially life-threatening conditions that fish in tropical regions can face during the dry season. This study investigated the air-breathing behavior, oxygen consumption, and respiratory responses of the air-breathing (AB) armored catfish Pterygoplichthys anisitsi. The hematological parameters and oxygen-binding characteristics of whole blood and stripped hemoglobin and the intermediate metabolism of selected tissue in normoxia, different hypoxic conditions, and after air exposure were also examined. In normoxia, this species exhibited high activity at night and AB behavior (2–5 AB h^?1). The exposure to acute severe hypoxia elicited the AB behavior (4 AB h^?1) during the day. Under progressive hypoxia without access to the water surface, the fish were oxyregulators with a critical O₂ tension, calculated as the inspired water O₂ pressure, as 47 ± 2 mmHg. At water O₂ tensions lower than 40 mmHg, the fish exhibited continuous apnea behavior. The blood exhibited high capacity for transporting O₂, having a cathodic hemoglobin component with a high Hb–O₂ affinity. Under severe hypoxia, the fish used anaerobic metabolism to maintain metabolic rate. Air exposure revealed physiological and biochemical traits similar to those observed under normoxic conditions.     

Genetic parameters for growth and survival traits in Pacific white shrimp Penaeus (Litopenaeus) vannamei from a nucleus population undergoing a two-stage selection program

A multivariate animal model and multi-generational data from a two-stage selection shrimp breeding program were used to estimate genetic parameters for a genetic nucleus of Penaeus (Litopenaeus) vannamei. A total of 408,648 records from years 2008 to 2010 production cycles provided by a Mexican hatchery were analyzed. The studied traits were survival from 0 to 28 days of age (S1), square root of body weight at 28 days of age (W1^1/2), survival from 65 to 130 days of age (S2), and body weight at 130 days of age (W2). Mean (standard deviation) for W1^1/2 and W2 were estimated as 5.4 mg^1/2 (1.55) and 13.6 g (3.1), respectively, while mean (standard deviation) for S1 and S2 (as proportions) were estimated as 0.20 (0.41) and 0.71 (0.45), respectively. Heritabilities for S1, W1^1/2, S2, and W2 were 0.03 ± 0.01, 0.13 ± 0.03, 0.04 ± 0.01, and 0.21 ± 0.04, respectively. Genetic correlations of S1 with W1^1/2, S2, and W2 were ?0.49 ± 0.21, ?0.29 ± 0. 21, and ?0.40 ± 0.16, respectively. Genetic correlations of W1^1/2 with S2, and W2 were 0.55 ± 0.17, and 0.71 ± 0.12, respectively, and genetic correlation between S2 and W2 was 0.56 ± 0.10. Results show that selection based on W2 has a positive effect on S2, while selection based on W1^1/2, as an early selection criterion, would increase the selection responses for W2 and S2.     

Pro-oxidant and antioxidant responses in the liver and kidney of wild Goodea gracilis and their relation with halomethanes bioactivation

In mammals, it has been shown that halomethanes (HM) are bioactivated by enzymes such as CYP 2E1 and the theta isoform of GST to produce reactive metabolites. However, in fish, little information is available, although HM can form autochthonously in aquatic environments. This study assessed the effect of HM in dusky splitfin (Goodea gracilis) from three lakes of the Valley of Mexico by analysing specific HM biomarkers as well as a broad range of biomarkers. The concentration of HM was a function of its half-life (higher in deep waters), while its precursors and solar radiation are secondary factors that determine its concentration. The kidney showed higher basal metabolism than the liver, probably because of its function as a haematopoietic and filtration organ. Using integrated biological response version 2 (IBRv2), it was found that the hepatic and renal O₂· content is a pro-oxidant force capable of inducing oxidative stress (ROOH, TBARS and RC=O). Early damage was found to be dependent on low concentrations of HM in Major Lake, whereas late damage was observed in fish exposed to higher concentrations of HM in Zumpango Lake and Ancient Lake. The activities of enzymes involved in antioxidant defence seemed to be inefficient. The quantitative assessment of biomarkers (ANOVA) and the estimate of parameter A obtained from IBRv2 provided different information. However, the data support the greater predictive power of IBRv2, but it requires a series of interrelated biomarkers to infer these possibilities. G. gracilis presents marked patterns of adaptation, which are dependant on the HM concentrations in environmental mixtures, although the response is complex and many toxicants could induce similar responses.     

Hypolipidemic Effect of Avocado (<Emphasis Type="Italic">Persea americana</Emphasis> Mill<Emphasis Type="Italic">)</Emphasis> Seed in a Hypercholesterolemic Mouse Model

Avocado seed contains elevated levels of phenolic compounds and exhibits antioxidant properties. We investigated the effect of Avocado Seed Flour (ASF) on the lipid levels in mice on a hyperlipidemic diet. The concentration of phenols was determined by high-performance liquid chromatography, antioxidant activity was evaluated using the Trolox equivalent antioxidant capacity method, and dietary fiber was measured using the Association of Official Analytical Chemists (AOAC) method. The LD₅₀ of ASF was determined using Lorke’s method and hypolipidemic activity was evaluated in a hypercholesterolemic model in mice. Protocatechuic acid was the main phenolic compound found in ASF, followed by kaempferide and vanillic acid. The total phenolic content in the methanolic extract of ASF was 292.00 ± 9.81 mg gallic acid equivalents/g seed dry weight and the antioxidant activity resulted in 173.3 μmol Trolox equivalents/g DW. In addition, a high content of dietary fiber was found (34.8%). The oral LD₅₀ for ASF was 1767 mg/kg body weight, and treatment with ASF significantly reduced the levels of total cholesterol, LDL-C, and prediction of the atherogenic index. Therefore, the antioxidant activity of phenolic compounds and dietary fiber in ASF may be responsible for the hypocholesterolemic activity of ASF in a hyperlipidemic model of mice.     

Does the Use of Chitosan Contribute to Oxalate Kidney Stone Formation?

Chitosan is widely used in the biomedical field due its chemical and pharmacological properties. However, intake of chitosan results in renal tissue accumulation of chitosan and promotes an increase in calcium excretion. On the other hand, the effect of chitosan on the formation of calcium oxalate crystals (CaOx) has not been described. In this work, we evaluated the antioxidant capacity of chitosan and its interference in the formation of CaOx crystals in vitro. Here, the chitosan obtained commercially had its identity confirmed by nuclear magnetic resonance and infrared spectroscopy. In several tests, this chitosan showed low or no antioxidant activity. However, it also showed excellent copper-chelating activity. In vitro, chitosan acted as an inducer mainly of monohydrate CaOx crystal formation, which is more prevalent in patients with urolithiasis. We also observed that chitosan modifies the morphology and size of these crystals, as well as changes the surface charge of the crystals, making them even more positive, which can facilitate the interaction of these crystals with renal cells. Chitosan greatly influences the formation of crystals in vitro, and in vivo analyses should be conducted to assess the risk of using chitosan.     

Gill denervation eliminates the barostatic reflex in a neotropical teleost,the tambaqui (<Emphasis Type="Italic">Colossoma macropomum</Emphasis>)

The baroreflex is one of the most important regulators of cardiovascular homeostasis in vertebrates. It begins with the monitoring of arterial pressure by baroreceptors, which constantly provide the central nervous system with afferent information about the status of this variable. Any change in arterial pressure relative to its normal state triggers autonomic responses, which are characterized by an inversely proportional change in heart rate and systemic vascular resistance and which tend to restore pressure normality. Although the baroreceptors have been located in mammals and other terrestrial vertebrates, their location in fish is still not completely clear and remains quite controversial. Thus, the objective of this study was to locate the baroreceptors in a teleost, the Colossoma macropomum. To do so, the occurrence and efficiency of the baroreflex were both analyzed when this mechanism was induced by pressure imbalancements in intact fish (IN), first-gill-denervated fish (G1), and total-gill-denervated fish (G4). The pressure imbalances were initiated through the administration of the α₁-adrenergic agonist phenylephrine (100 µg kg^?1) and the α₁-adrenergic antagonist prazosin (1 mg kg^?1). The baroreflex responses were then analyzed using an electrocardiogram that allowed for the measurement of the heart rate, the relationship between pre- and post-pharmacological manipulation heart rates, the time required for maximum chronotropic baroreflex response, and total heart rate variability. The results revealed that the barostatic reflex was attenuated in the G1 group and nonexistent in G4 group, findings which indicate that baroreceptors are exclusively located in the gill arches of C. macropomum.