Efeito do sombreamento em variedades de Stylosanthes guianensis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resistência de progênies de Stylosanthes capitata e S. macrocephala à antracnose causada por Colletotrichum gloeosporioides

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Identification of endocannabinoid system-modulating N-alkylamides from Heliopsis helianthoides var. scabra and Lepidium meyenii.

The discovery of the interaction of plant-derived N-alkylamides (NAAs) and the mammalian endocannabinoid system (ECS) and the existence of a plant endogenous N-acylethanolamine signaling system have led to the re-evaluation of this group of compounds. Herein, the isolation of seven NAAs and the assessment of their effects on major protein targets in the ECS network are reported. Four NAAs, octadeca-2E,4E,8E,10Z,14Z-pentaene-12-ynoic acid isobutylamide (1), octadeca-2E,4E,8E,10Z,14Z-pentaene-12-ynoic acid 2'-methylbutylamide (2), hexadeca-2E,4E,9Z-triene-12,14-diynoic acid isobutylamide (3), and hexadeca-2E,4E,9,12-tetraenoic acid 2'-methylbutylamide (4), were identified from Heliopsis helianthoides var. scabra. Compounds 2-4 are new natural products, while 1 was isolated for the first time from this species. The previously described macamides, N-(3-methoxybenzyl)-(9Z,12Z,15Z)-octadecatrienamide (5), N-benzyl-(9Z,12Z,15Z)-octadecatrienamide (6), and N-benzyl-(9Z,12Z)-octadecadienamide (7), were isolated from Lepidium meyenii (Maca). N-Methylbutylamide 4 and N-benzylamide 7 showed submicromolar and selective binding affinities for the cannabinoid CB1 receptor (Ki values of 0.31 and 0.48 μM, respectively). Notably, compound 7 also exhibited weak fatty acid amide hydrolase (FAAH) inhibition (IC50 = 4 μM) and a potent inhibition of anandamide cellular uptake (IC50 = 0.67 μM) that was stronger than the inhibition obtained with the controls OMDM-2 and UCM707. The pronounced ECS polypharmacology of compound 7 highlights the potential involvement of the arachidonoyl-mimicking 9Z,12Z double-bond system in the linoleoyl group for the overall cannabimimetic action of NAAs. This study provides additional strong evidence of the endocannabinoid substrate mimicking of plant-derived NAAs and uncovers a direct and indirect cannabimimetic action of the Peruvian Maca root.

Acid-base physiology response to ocean acidification of two ecologically and economically important holothuroids from contrasting habitats, Holothuria scabra and Holothuria parva

Sea cucumbers are dominant invertebrates in several ecosystems such as coral reefs, seagrass meadows and mangroves. As bioturbators, they have an important ecological role in making available calcium carbonate and nutrients to the rest of the community. However, due to their commercial value, they face overexploitation in the natural environment. On top of that, occurring ocean acidification could impact these organisms, considered sensitive as echinoderms are osmoconformers, high-magnesium calcite producers and have a low metabolism. As a first investigation of the impact of ocean acidification on sea cucumbers, we tested the impact of short-term (6 to 12 days) exposure to ocean acidification (seawater pH 7.7 and 7.4) on two sea cucumbers collected in SW Madagascar, Holothuria scabra, a high commercial value species living in the seagrass meadows, and H. parva, inhabiting the mangroves. The former lives in a habitat with moderate fluctuations of seawater chemistry (driven by day-night differences) while the second lives in a highly variable intertidal environment. In both species, pH of the coelomic fluid was significantly negatively affected by reduced seawater pH, with a pronounced extracellular acidosis in individuals maintained at pH 7.7 and 7.4. This acidosis was due to an increased dissolved inorganic carbon content and pCO2 of the coelomic fluid, indicating a limited diffusion of the CO2 towards the external medium. However, respiration and ammonium excretion rates were not affected. No evidence of accumulation of bicarbonate was observed to buffer the coelomic fluid pH. If this acidosis stays uncompensated for when facing long-term exposure, other processes could be affected in both species, eventually leading to impacts on their ecological role.

Use of micro-algae concentrates for hatchery culture of sandfish, Holothuria scabra

Three Instant Algae® (Reed Mariculture Inc., Campbell, CA, USA, 95008) products: (1) mono-cultured Isochrysis sp. (Haptophyceae) (Isochrysis 1800®); (2) mono-cultured Pavlova sp. (Haptophyceae) (Pavlova 1800®); and (3) mono-cultured Thalassiosira weissflogii (Bacillariophyceae) (TW 1200®) were used to feed sandfish (Holothuria scabra) larvae both singly and in ternary combination to assess their nutritional efficacy. Two-day auriculariae were held at a starting density of 0.3 mL-1 and were initially fed a daily ration equivalent to the dry weight of 10,000 cells mL-1 of Isochrysis 1800®. This ration was increased by the dry weight equivalent of 1000 cells mL-1 of Isochrysis 1800® per day as larval development proceeded. Post-settled larvae fed TW 1200® were significantly larger than those fed the ternary diet, Isochrysis 1800® or Pavlova 1800®. There were significant differences in the mean (±SE) survival of auriculariae and post-settled larvae between treatments and survival to settlement was significantly higher (P < 0.05) for larvae fed TW 1200® (13.7 ± 0.7%) alone. Laval development, competency and survival were significantly correlated with dietary levels of total protein, lipid and nitrogen-free extract (NFE), and with total polyunsaturated fatty acid (PUFA) content of the diets, and the levels of some specific fatty acids (FA). The proportion of late auriculariae with hyaline spheres (day 13), numbers of competent doliolariae (day 15) and the total length of post-settled larvae (day 21) were all positively correlated with dietary NFE and palmitic acid (16:0) contents, as well as dietary EPA: DHA ratio. This study is the first comprehensive assessment of the nutritional value of micro-algae concentrates for sandfish larvae based on their nutrient compositions. Our study confirms the feasibility of using commercially available microalgae concentrates as a sole food source for hatchery culture of sandfish, and is the first to report successful hatchery culture of H. scabra without using live micro-algae. All micro-algae concentrates used in this study proved nutritious for H. scabra larvae and supported normal growth and development and relatively high survival, through settlement. Use of commercially available micro-algae concentrates as a replacement for live micro-algae in sandfish hatcheries supports development of cheaper, simpler larval rearing protocols for this species. Statement of relevance: Hatchery culture of sandfish using micro-algae concentrates, without the use of live micro-algae, is a significant finding that supports development of cheaper, simpler larval rearing protocols for this species. Our study provides detailed nutritional compositional data for the products used and on this basis we were able to deduce new information relating to key nutrients for sea cucumber larvae.

Development of hyaline spheres in late auriculariae of sandfish, Holothuria scabra : is it a reliable indicator of subsequent performance?

This study assessed the influence of diet composition on hyaline sphere (HS) development in auricularia larvae of the sandfish, Holothuria scabra, and the subsequent relationships between the presence and size of hyaline spheres and competency through settlement and early juvenile performance. Two-day old larvae were fed one of three commercially available micro-algae diets that varied in their nutrient compositions: (1) Isochrysis sp. (Haptophyceae); (2) Pavlova sp. (Haptophyceae); and (3) Thalassiosira weissflogii (Bacillariophyceae) or a ternary combination of the three. There were positive significant correlations between HS development in late auriculariae on days 10, 11, 12 and 13 post-fertilisation, and the proportion of competent doliolariae on day 15, post-settlement size (day 21) and post-settlement survival (day 25). The dietary components that most strongly influenced these relationships were carbohydrates and the n-3 polyunsaturated fatty acids arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Our result confirm the strong relationship between HS formation in late auriculariae of sandfish and subsequent larval competency through settlement. As such, the presence and size of HS is a reliable indicator of subsequent performance for sandfish. Given that HS development was influenced by the nutrients available to sandfish auriculariae, there is clear opportunity for development of more appropriate diets for hatchery culture of this species that will improve HS formation and larval performance supporting improved hatchery production. Statement of relevance Our results have confirmed that for sandfish larvae, the presence and size of HS at the end of the auricularia stage, is indeed a reliable indicator of subsequent performance. Our results have also confirmed that HS formation and size is significantly influenced by the nutrient composition of the auricularia diet, and that there are significant positive correlations between HS formation and dietary levels of carbohydrate, EPA:DHA and EPA:ARA ratios. This information provides a strong basis for development of more appropriate diets for sandfish larvae that will improve HS formation and larval performance during hatchery culture and in turn improve hatchery production of this species.

Stylosanthes guianensis cv. BRS Bela managed as organic fodder bank for supplementation of lactation crossbred cows in the Cerrado.

2016

Organic management of Brachiaria brizantha cv. Marandu pasture mixed with Stylosanthes spp. in the Cerrado.

2016

Especificidade de uma variedade nativa de "alfafa do Nordeste" (Stylosanthes gracilis) na simbiose com Rhizobium sp.

1972

Resistencia natural a estreptomicina e eficiência de estirpes de Rhizobium nativas nos cerrados associadas à Stylosanthes.

1983

CgDN24 : a gene involved in hyphal development in the fungal phytopathogen Colletotrichum gloeosporioides

A cDNA corresponding to a transcript induced in culture by N starvation, was identified in Colletotrichum gloeosporioides by a differential hybridisation strategy. The cDNA comprised 905 bp and predicted a 215 aa protein; the gene encoding the cDNA was termed CgDN24. No function for CgDN24 could be predicted by database homology searches using the cDNA sequence and no homologues were found in the sequenced fungal genomes. Transcripts of CgDN24 were detected in infected leaves of Stylosanthes guianensis at stages of infection that corresponded with symptom development. The CgDN24 gene was disrupted by homologous recombination and this led to reduced radial growth rates and the production of hyphae with a hyperbranching phenotype. Normal sporulation was observed, and following conidial inoculation of S. guianensis, normal disease development was obtained. These results demonstrate that CgDN24 is necessary for normal hyphal development in axenic culture but dispensable for phytopathogenicity. © 2005 Elsevier GmbH. All rights reserved.

Seasonal changes in pasture quality and diet selection and their relationship with liveweight gain of steers grazing tropical grass and grass-legume pastures in northern Australia.

The variation in liveweight gain in grazing beef cattle as influenced by pasture type, season and year effects has important economic implications for mixed crop-livestock systems and the ability to better predict such variation would benefit beef producers by providing a guide for decision making. To identify key determinants of liveweight change of Brahman-cross steers grazing subtropical pastures, measurements of pasture quality and quantity, and diet quality in parallel with liveweight were made over two consecutive grazing seasons (48 and 46 weeks, respectively), on mixed Clitoria ternatea/grass, Stylosanthes seabrana/grass and grass swards (grass being a mixture of Bothriochloa insculpta cv. Bisset, Dichanthium sericeum and Panicum maximum var. trichoglume cv. Petrie). Steers grazing the legume-based pastures had the highest growth rate and gained between 64 and 142 kg more than those grazing the grass pastures in under 12 months. Using an exponential model, green leaf mass, green leaf %, adjusted green leaf % (adjusted for inedible woody legume stems), faecal near infrared reflectance spectroscopy predictions of diet crude protein and diet dry matter digestibility, accounted for 77, 74, 80, 63 and 60%, respectively, of the variation in daily weight gain when data were pooled across pasture types and grazing seasons. The standard error of the regressions indicated that 95% prediction intervals were large (+/- 0.42-0.64 kg/head.day) suggesting that derived regression relationships have limited practical application for accurately estimating growth rate. In this study, animal factors, especially compensatory growth effects, appeared to have a major influence on growth rate in relation to pasture and diet attributes. It was concluded that predictions of growth rate based only on pasture or diet attributes are unlikely to be accurate or reliable. Nevertheless, key pasture attributes such as green leaf mass and green leaf% provide a robust indication of what proportion of the potential growth rate of the grazing animals can be achieved.

Composición e identificación de malezas en pasto estrella (Cynodon nemfluencis), Cofradía, Carretera vieja Tipitapa-Managua

Con el objetivo de caracterizar la composición botánica de especies forrajera y no forrajera en sistemas de pastura de pasto estrella (Cynodon nlenfluencis), en la Hacienda Los Tercios, comarca Cofradía, km 16 ½ carretera Managua – Tipitapa, se realizó el presente trabajo. Para la ejecución del mismo y dada las posibilidades se seleccionaron dos condiciones, una con árboles y otra sin árboles, donde se realizó primeramente la determinación de la composición botánica, utilizando para ello el método del doble muestreo, simultáneamente se realizó la primera colecta de material vegetativo, el cual posteriormente fue identificado en el herbario de la UNA, herbario Nacional y a través de consultas con expertos en la materia (Botánicos). A cada una de las especies identificadas se les realizó fichas botánicas, que comprendieron nombre común, nombre científico, origen y distribución, características de las plantas, aptitudes forrajera y cuando fue posible si presentaba características anticualutativas o antinutricionales. Posteriormente se realizó una valoración técnica, para considerar el estado de dichas pasturas y las implicaciones económicas que estas podrían tener en manejo y recuperación. Se determinaron cuatro escenarios, 1) con árboles en el cerco; 2) con árboles en un 50%; 3) con árboles en un 75% y 4) con árboles en un 90%, registrándose coberturas vegetales que fluctuaron de 60 a 95%, y composición de las especies forrajeras en rangos similares. Se identificaron 16 familias, 25 géneros y 25 especies, dentro de los cuales destacaron por su mayor presencia las especies de escoba lisa (Sida cuta), bledo espinoso (Amaranthus espinosus), chilillo de gato (Achyranthes aspera), baba de culebra (Asclepia curasavica), flor amarilla (Melampodium divaricatum), dormilona (Mimosa pudica), espino de playa ( Phytecelobium dulce), catapanzas (Cucurbita spp), entre otras, también se considera como forajera a algunas especies leguminosa herbáceas como patito (Centrocema plumieri), centro (Centrocema pubescens), pega pega (Desmodium incatum, Desmodium spp), calopo (Calopogodium mucunoides; C. galactoides), Aeschynomene scabra y A. americana se observó una diversidad de especies, cuando existían árboles en el área de pasturas, minimizándose estas cuando no existían árboles. A través del análisis técnico – económico se determinó que los factores cobertura vegetal y porcentaje de malezas son de mucha importancia, en el manejo y productividad de las pasturas y que aun cuando se tenga pasturas de buen comportamiento productivo, se registran perdidas, lo cual indica que en las pasturas no todo es forrajero.

Efecto de rotación de cultivos y control de malezas sobre la cenosis de malezas en los cultivos maíz (Zea mays L.), sorgo (Sorghum bicolor (L) moench) y pepino (Cucumis sativus L.)

En este trabajo se estudia la influencia de diferentes métodos de control de malezas en diferentes rotaciones de cultivos, la dinámica de asociaciones de malezas y el crecimiento y desarrollo de loe cultivos. El ensayo se inició en la postrera 1987 en la Estación Experimental de cultivos no tradicionales "Campos Azules" en Masatepe, Masaya, considerando en este trabajo los resultados de la siembra de primera 1990. Se estudió las rotaciones sorgo-sorgo, sorgo-maíz, soya-maíz, soya-pepino y sorgo-pepino, y los métodos de control químico, control por período crítico y control por limpio periódica. Los resultados demuestran que los controles químicos y limpias periódicas efectuaron un control satisfactorio de las malezas, mientras el control por período crítico (con 1 pase de azadón) quedé insuficiente, debido a la predominancia de especies dicotiledóneas como Richardia scabra y Baltimora recta, de competitividad alargada y tardía. Las rotaciones influyeron sobre el nivel del enmalezamiento, siendo más bajo en sorgo-sorgo y sorgo-maíz que en las demás rotaciones con participación de cultivos dicotiledóneas (soya, pepino). En cuanto a rendimiento los mejores resultados se obtuvieron con sorgo-maíz y soya-pepino.