Antimicrobial and Antimycobacterial Activity of Cyclostellettamine Alkaloids from Sponge Pachychalina sp.

Cyclostellettamines A – F (1 – 6) isolated from the sponge Pachychalina sp. and cyclostellettamines G - I, K and L (7 – 11) obtained by synthesis were evaluated in bioassays of antimicrobial activity against susceptible and antibiotic-resistant Staphylococcus aureus, Pseudomonas aeruginosa and antibiotic-susceptible Escherichia coli and Candida albicans, as well as in antimycobacterial activity against Mycobacterium tuberculosis H37Rv bioassays. The results obtained indicated that cyclostellettamines display different antimicrobial activity depending on the alkyl-chain size, suggesting that, if a mechanism-of action is implied, it is dependent on the distance between the two pyridinium moieties of cyclostellettamines.     

The role of oocyte-secreted factors GDF9 and BMP15 in follicular development and oogenesis

Ovarian physiology is controlled by endocrine and paracrine signals, and the transforming growth factor β (TGFβ) superfamily has a pivotal role in this control. The Bone morphogenetic protein 15 (BMP15) and Growth differentiation factor 9 (GDF9) genes are relevant members of the TGFβ superfamily that encode proteins secreted by the oocytes into the ovarian follicles. Through a paracrine signalling pathway, these factors induce the follicular somatic cells to undergo mitosis and differentiation during follicular development. These events are controlled by a mutually dependent and coordinated fashion during the formation of the granulosa cell layers. Many studies have contributed to our knowledge concerning the paracrine factors acting within the follicular environment, especially regarding GDF9 and BMP15. We aimed to review the relevant contributions of these two genes to animal reproductive physiology.     

A modified agglutination test for the diagnosis of Besnoitia besnoiti infection

Bovine besnoitiosis is caused by Besnoitia besnoiti, an obligate intracellular apicomplexan parasite. Affected animals present cutaneous and systemic manifestations and the disease may lead to considerable economic losses. Although generally associated to tropical and subtropical areas, bovine besnoitiosis is now considered an emergent disease in Europe, due to the increasing number of new cases and apparent geographical expansion. In this study we evaluated the performance of a modified agglutination test (B-MAT) in the serodiagnosis of bovine besnoitiosis in comparison to the indirect immunofluorescent-antibody test (IFAT). To establish optimal protocol conditions we used bovine sera with a known infection status for B. besnoiti infection. Positive animals (n=36) presented B. besnoiti dermal cysts and anti-B. besnoiti specific antibodies, as determined by the indirect immunofluorescence test (IFAT). Negative animals (n=103) were from non-endemic areas in Portugal and negative by the IFAT. From here, we evaluated the sensitivity and specificity of the B-MAT relative to the IFAT with a panel of sera from herds with history of bovine besnoitiosis in Portugal, Spain and France (n=402), using three serum dilutions (1:80, 1:160, 1:320). Considering the positive cut-off at 1:160 serum dilution, the B-MAT showed an almost perfect test agreement with the IFAT; (κ=0.968; 95% CI: 0.941-0.996) with a relative sensitivity of 97.2% (95% CI: 94.1-100%) and a relative specificity of 99.3% (95% CI: 98.4-100%). As a simple and inexpensive technique the B-MAT represents a valuable tool for the diagnosis and study of the epidemiology of bovine besnoitiosis.     

Applying a Lagrangian dispersion analysis to infer carbon dioxide and latent heat fluxes in a corn canopy

Warland and Thurtell (2000) proposed an analytical dispersion Lagrangian analysis (hereafter WT analysis) to relate the mean scalar concentration field to source profiles inside the canopy. The first objective of this study was to evaluate the performance of the WT analysis with existing turbulence statistics parameterizations in a corn canopy, by comparing its inferred net ecosystem CO₂ exchange (NEE) and latent heat flux (λE) with eddy covariance measurements. The second objective was to assess the performance of the WT analysis to infer the soil CO₂ flux. Four parameterizations of turbulence statistics were used to estimate Lagrangian time scale (T_L) and standard deviation of vertical wind velocity (σ_w) profiles. The estimated T_L and σ_w profiles were then corrected for atmospheric stability conditions. The field experiment was carried out in a corn field from August to October 2007 and 2008. Profiles of water vapour and CO₂ mixing ratios were measured using a multiport sampling system connected to an infrared gas analyzer. Wind velocity within and above the canopy and eddy covariance measurements over the canopy were taken. The soil respiration, estimated using the WT analysis, was compared to estimates obtained by an empirical model. WT analysis fluxes showed good correlation (R² = 0.77-0.88) with NEE and λE obtained by the eddy covariance technique, but overestimated net fluxes, especially when corrections for atmospheric stability were applied. The optimization of T_L and σ_w profiles using in-canopy turbulence measurements improved the agreement between measured and modeled NEE and λE. Inferred soil CO₂ fluxes were underestimated and were poorly correlated (R² = 0.02-0.01) with estimates obtained using an empirical model based on soil temperature. This poor performance in estimating the soil respiration is likely caused by the decoupling between inside and above canopy flows.     

Soil microbiological attributes under summer/winter crops rotation in a no-tillage system

Knowledge of the effect of a multiple combination of summer/winter crop rotation on the microbiological properties of soil would allow a more adequate response to its use. This study aimed to evaluate the effect of the rotation of three summer crops (continuous soybean, continuous maize and soybean/maize rotation) in combination with seven winter crops (maize, sunflower, oilseed radish, millet, pigeon pea, sorghum and sunn hemp) on the microbiological properties of the soil. A soybean/maize (SM) rotation had a greater influence on microbial biomass than continuous maize (MM) and continuous soybean (SS). Urease and phosphatase activities were not affected by the crop rotation. Dehydrogenase activity was higher in continuous crops (MM and SS) than in SM, whereas respiratory activity was higher in SM than in continuous crops. For the SM rotation, the main variables selected by principal components analysis were microbial biomass C, N and P, respiratory and phosphatase activities, and microbial quotient. Pigeon pea, sorghum and sunn hemp had a greater effect on soil properties than the other winter crops. In general, the degree of influence of the summer and winter crops on the microbiological soil properties can be ranked as follows: SM > MM > SS, and millet > sorghum > sunn hemp > radish > pigeon pea > maize, respectively.     

Neural networks in climate spatialization and their application in the agricultural zoning of climate risk for sunflower in different sowing dates

ABSTRACT

Sunflower is a species that is sensitive to local climate conditions. However, studies that use artificial neural networks (ANNs) to evaluate this influence and create tools such as agricultural zoning of climate risk (ZARC) have not been conducted for this species. Due to the importance of sunflower as a human food source and for biodiesel production, and also the necessity of conducting research to evaluate the suitability of this oleaginous species under different climatic conditions. Thus, we seek to construct a ZARC for sunflower in Brazil simulating sowing on different dates and using meteorological elements spatialized by ANNs. Climate data were used: air temperature (T), rainfall (P), relative air humidity (UR), solar radiation (MJ_m^?2_d^?1) and wind velocity (U²). Climatic regions considered suitable for the cultivation of sunflower had average annual values for T between 20 and 28°C, P between 500 and 1.500 mm per cycle, and soil water deficit (DEF) below 140 mm per cycle. A neural network is an efficient tool that can be used in spatialization of climate variables quickly and accurately. Sunflower sowing in the spring and summer are the ones that provide the largest suitable areas in southeastern Brazil, with 58.13 and 64.36% of suitable areas, respectively.     

Heterochromatin type, amount and distribution in wild species of chili peppers (Capsicum, Solanaceae)

Triple staining with the fluorochromes chromomycin A3, distamycin A and 4′-6-diamidino-2-phenylindole (CMA/DA/DAPI) was applied to somatic metaphases and interphase nuclei of 11 taxa of wild chili peppers (Capsicum), with 2n = 2x = 24 (C. annuum var. glabriusculum, C. cardenasii, C. chacoense, C. flexuosum, C. galapagoense, C. eximium, C. praetermissum and C. tovarii) and 2n = 2x = 26 (C. recurvatum, C. rhomboideum and C. villosum) to analyse heterochromatin type, amount and distribution in wild members of this genus. Heterochromatic banding patterns allowed the identification of all the taxa examined and contributed to their taxonomic grouping. GC-rich heterochromatin (CMA+/DAPI?) was typical in all taxa; only C. praetermissum possessed also AT-rich (CMA?/DAPI+) and mixed GC- and AT-rich (CMA+/DAPI+) bands. Heterochromatin amount (expressed as % of karyotype length) ranged between 1.72 (C. chacoense) and 16.82 (C. flexuosum) and was positively correlated with karyotype length in most of the taxa examined. Heterochromatin located mainly at terminal position of chromosomes but intercalary position prevailed in C. flexuosum. Nucleolus organizer regions (NOR)-associated GC-rich heterochromatin was exclusively terminal and included the distal macrosatellite and a small portion on the corresponding arm. In all the taxa analysed, an equilocal heterochromatin distribution in non-homologous chromosomes of karyotype was observed, suggesting concerted evolution of heterochromatin dispersion in Capsicum.     

Modulation of Uptake and Translocation of Iron and Copper from Root to Shoot in Common Bean by Siderophore-Producing Microorganisms

Microbes have developed high-affinity uptake mechanisms to assimilate iron (Fe) and other metals such as aluminum (Al), gallium (Ga), chromium (Cr), and copper (Cu). Siderophores, which are metal chelating compounds, and membrane receptor proteins are involved in these specialized mechanisms. A few siderophore-producing microorganisms associated with plant roots also influence the uptake of some metals. In this study, the potential microbial-assisted Cu and Fe uptake by Phaseolus vulgaris (common bean) plants was evaluated. Seedlings of cultivated common bean varieties Bayo-INIFAP (B) and Negro-150 (N) and wild types yellowish (WY) and black (WB) were developed in the presence of a Cu and Fe solution and associated with the siderophore-producing microorganisms R. leguminosarumbv. Phaseoli (strains 19, 44, and 46); Pseudomonas fluorescens(strain Avm), and Azospirillum brasilense (strain 154). Seedlings of cultivated variety N and black wild type WB inoculated with the strain CPMex.44 accumulated 71% and 30% more Fe than the un-inoculated plants, respectively; however, the wild black bean accumulated the highest absolute amount of Fe (221.56 mg/kg of dry matter) as compared with the cultivated black variety N (126.16 mg/kg of dry matter) (P < 0.05). In the wild type WY seedlings, the highest Fe accumulation was observed when the seeds were inoculated with the Pseudomonas strain Avm (206 mg/kg of dry matter) (P < 0.05). The interaction of Pseudomonas strain Avm with seedlings of the cultivated B variety and the wild type WB promoted the highest accumulation of Cu (51 and 54 mg/kg of dry matter, respectively), 7 and 14 mg more than in the respective non-inoculated seedlings. No promotion of Fe accumulation was observed in the seedlings of the cultivated B variety and in roots; instead, less Fe was accumulated. The wild type WY did not show any improvement in Cu accumulation. In this study, Rhizobiumstrains promoted Fe but not Cu uptake in P. vulgaris seedlings while Pseudomonas strains promoted the uptake of both Cu and Fe.