Atmospheric Absorption of Fluoride by Cultivated Species. Leaf Structural Changes and Plant Growth

Fluoride (F) is an air pollutant that causes phytotoxicity. Besides the importance of this, losses of agricultural crops in the vicinity of F polluting industries in Brazil have been recently reported. Injuries caused to plant leaf cell structures by excess F are not well characterized. However, this may contribute to understanding the ways in which plant physiological and biochemical processes are altered. A study evaluated the effects of the atmospheric F on leaf characteristics and growth of young trees of sweet orange and coffee exposed to low (0.04 mol L(-1)) or high (0.16 mol L(-1)) doses of HF nebulized in closed chamber for 28 days plus a control treatment not exposed. Gladiolus and ryegrass were used as bioindicators in the experiment to monitor F exposure levels. Fluoride concentration and dry mass of leaves were evaluated. Leaf anatomy was observed under light and electron microscopy. High F concentrations (similar to 180 mg kg(-1)) were found in leaves of plants exposed at the highest dose of HF. Visual symptoms of F toxicity in leaves of citrus and coffee were observed. Analyses of plant tissue provided evidence that F caused degeneration of cell wall and cytoplasm and disorganization of bundle sheath, which were more evident in Gladiolus and coffee. Minor changes were observed for sweet orange and ryegrass. Increase on individual stomatal area was also marked for the Gladiolus and coffee, and which were characterized by occurrence of opened ostioles. The increased F absorption by leaves and changes at the structural and ultrastructural level of leaf tissues correlated with reduced plant growth.

DNA sequences generated by BCH codes over GF(4)

The question raised by researchers in the field of mathematical biology regarding the existence of error-correcting codes in the structure of the DNA sequences is answered positively. It is shown, for the first time, that DNA sequences such as proteins, targeting sequences and internal sequences are identified as codewords of BCH codes over Galois fields.

QTL mapping for reaction to Phaeosphaeria leaf spot in a tropical maize population

Phaeosphaeria leaf spot (PLS) is an important disease in tropical and subtropical maize (Zea mays, L.) growing areas, but there is limited information on its inheritance. Thus, this research was conducted to study the inheritance of the PLS disease in tropical maize by using QTL mapping and to assess the feasibility of using marker-assisted selection aimed to develop genotypes resistance to this disease. Highly susceptible L14-04B and highly resistant L08-05F inbred lines were crossed to develop an F(2) population. Two-hundred and fifty six F(2) plants were genotyped with 143 microsatellite markers and their F(2:3) progenies were evaluated at seven environments. Ten plants per plot were evaluated 30 days after silk emergence following a rating scale, and the plot means were used for analyses. The heritability coefficient on a progeny mean basis was high (91.37%), and six QTL were mapped, with one QTL on chromosomes 1, 3, 4, and 6, and two QTL on chromosome 8. The gene action of the QTL ranged from additive to partial dominance, and the average level of dominance was partial dominance; also a dominance x dominance epistatic effect was detected between the QTL mapped on chromosome 8. The phenotypic variance explained by each QTL ranged from 2.91 to 11.86%, and the joint QTL effects explained 41.62% of the phenotypic variance. The alleles conditioning resistance to PLS disease of all mapped QTL were in the resistant parental inbred L08-05F. Thus, these alleles could be transferred to other elite maize inbreds by marker-assisted backcross selection to develop hybrids resistant to PLS disease.

Diversity of endophytic yeasts from sweet orange and their localization by scanning electron microscopy

Endophytes are microorganisms that colonize plant tissues internally without causing harm to the host. Despite the increasing number of studies on sweet orange pathogens and endophytes, yeast has not been described as a sweet orange endophyte. In the present study, endophytic yeasts were isolated from sweet orange plants and identified by sequencing of internal transcribed spacer (ITS) rRNA. Plants sampled from four different sites in the state of Sao Paulo, Brazil exhibited different levels of CVC (citrus variegated chlorosis) development. Three citrus endophytic yeasts (CEYs), chosen as representative examples of the isolates observed, were identified as Rhodotorula mucilaginosa, Pichia guilliermondii and Cryptococcus flavescens. These strains were inoculated into axenic Citrus sinensis seedlings. After 45 days, endophytes were reisolated in populations ranging from 10(6) to 10(9) CFU/g of plant tissue, but, in spite of the high concentrations of yeast cells, no disease symptoms were observed. Colonized plant material was examined by scanning electron microscopy (SEM), and yeast cells were found mainly in the stomata and xylem of plants, reinforcing their endophytic nature. P. guilliermondii was isolated primarily from plants colonized by the causal agent of CVC, Xylella fastidiosa. The supernatant from a culture of P. guilliermondii increased the in vitro growth of X. fastidiosa, suggesting that the yeast could assist in the establishment of this pathogen in its host plant and, therefore, contribute to the development of disease symptoms.

Endophytic population of Pantoea agglomerans in citrus plants and development of a cloning vector for endophytes

Harmless bacteria inhabiting inner plant tissues are termed endophytes. Population fluctuations in the endophytic bacterium Pantoea agglomerans associated with two species of field cultured citrus plants were monitored over a two-year period. The results demonstrated that populations of P. agglomerans fluctuated in Citrus reticulata but not C. sinensis. A cryptic plasmid pPA3.0 (2.9 kb) was identified in 35 out of 44 endophytic isolates of P. agglomerans and was subsequently sequenced. The origins of replication were identified and nine out of 18 open reading frames (ORFs) revealed homology with described proteins. Notably, two ORFs were related to cellular transport systems and plasmid maintenance. Plasmid pPA3.0 was cloned and the gfp gene inserted to generate the pPAGFP vector. The vector was introduced into P. agglomerans isolates and revealed stability was dependent on the isolate genotype, ninety-percent stability values were reached after 60 hours of bacterial cultivation in most evaluated isolates. In order to definitively establish P. agglomerans as an endophyte, the non-transformed bacterium was reintroduced into in vitro cultivated seedlings and the density of inner tissue colonization in inoculated plants was estimated by bacterium re-isolation, while the tissue niches preferred by the bacterium were investigated by scanning electronic microscopy (SEM). Cells from P. agglomerans (strain ARB18) at similar densities were re-isolated from roots, stems and leaves and colonization of parenchyma and xylem tissues were observed. Data suggested that P. agglomerans is a ubiquitous citrus endophyte harboring cryptic plasmids. These characteristics suggest the potential to use the bacterium as a vehicle to introduce new genes in host plants via endophytic bacterial transformation.

Soil CO(2) emission estimated by different interpolation techniques

Soil CO(2) emissions are highly variable, both spatially and across time, with significant changes even during a one-day period. The objective of this study was to compare predictions of the diurnal soil CO(2) emissions in an agricultural field when estimated by ordinary kriging and sequential Gaussian simulation. The dataset consisted of 64 measurements taken in the morning and in the afternoon on bare soil in southern Brazil. The mean soil CO(2) emissions were significantly different between the morning (4.54 mu mol m(-2) s(-1)) and afternoon (6.24 mu mol m(-2) s(-1)) measurements. However, the spatial variability structures were similar, as the models were spherical and had close range values of 40.1 and 40.0 m for the morning and afternoon semivariograms. In both periods, the sequential Gaussian simulation maps were more efficient for the estimations of emission than ordinary kriging. We believe that sequential Gaussian simulation can improve estimations of soil CO(2) emissions in the field, as this property is usually highly non-Gaussian distributed.

Effect of follicular wave synchronization on in vitro embryo production in heifers

Aiming to achieve the ideal time of ovum pick-up (OPU) for in vitro embryo production (IVP) in crossbred heifers, two Latin square design studies investigated the effect of ovarian follicular wave synchronization with estradiol benzoate (EB) and progestins. For each experiment, crossbred heifers stage of estrous cycle was synchronized either with a norgestomet ear implant (Experiment 1) or a progesterone intravaginal device (Experiment 2) for 7d, followed by the administration of 150 mu g D-cloprostenol. On Day 7, all follicles >3 mm in diameter were aspirated and implants/devices were replaced by new ones. Afterwards, implant/device replacement was conducted every 14 d. Each experiment had three treatment groups. In Experiment I (n = 12), heifers in Group 2X had their follicles aspirated twice a week and those in Groups 1X and 1X-EB were submitted to OPU once a week for a period of 28 d. Heifers from Group 1X-EB also received 2 mg EB i.m. immediately after each OPU session. In Experiment 2 (n = 11), animals from Group 0EB did not receive EB while heifers in Groups 2EB and 5EB received 2 and 5 mg of EB respectively, immediately after OPU. The OPU sessions were performed once weekly for 28 d. Therefore, in both experiments, four OPU sessions were performed in heifers aspirated once a week and in Experiment 1, eight OPU sessions were done in heifers aspirated twice a week. Additionally, during the 7-d period following follicular aspiration, ovarian ultrasonography examinations were conducted to measure diameter of the largest follicle and blood samples were collected for FSH quantification by RIA. In Experiment 1, all viable oocytes recovered were in vitro matured and fertilized. Results indicated that while progestin and EB altered follicular wave patterns, this treatment did not prevent establishment of follicular dominance on the ovaries of heifers during OPU at 7-d intervals. Furthermore, the proposed stage of follicular wave synchronization strategies did not improve the number and quality of the recovered oocytes, or the number of in vitro produced embryos. (C) 2009 Elsevier B.V. All rights reserved.

Short communication: An evaluation of the effectiveness of Lactobacillus buchneri 40788 to alter fermentation and improve the aerobic stability of corn silage in farm silos

The objective of this study was to determine if the effects of inoculation with Lactobacillus buchneri 40788 were detectable when applied to whole-plant corn stored in farm silos. Corn silage was randomly sampled from farms in Wisconsin, Minnesota, and Pennsylvania, and was untreated (n = 15) or treated with an inoculant (n = 16) containing L. buchneri 40788 alone or this organism combined with Pediococcus pentosaceus during May and June 2007. Corn silage that was removed from the silo face during the morning feeding was sampled, vacuum-packed, and heat sealed in polyethylene bags and shipped immediately to the University of Delaware for analyses. Silage samples were analyzed for dry matter (DM), nutrient composition, fermentation end-products, aerobic stability, and microbial populations. The population of L. buchneri in silages was determined using a real-time quantitative PCR method. Aerobic stability was measured as the time after exposure to air that it took for a 2 degrees C increase above an ambient temperature. The DM and concentrations of lactic and acetic acids were 35.6 and 34.5, 4.17 and 4.85, and 2.24 and 2.41%, respectively, for untreated and inoculated silages and were not different between treatments. The concentration of 1,2-propanediol was greater in inoculated silages (1.26 vs. 0.29%). Numbers of lactic acid bacteria determined on selective agar were not different between treatments. However, the numbers of L. buchneri based on measurements using real-time quantitative PCR analysis were greater and averaged 6.46 log cfu-equivalents/g compared with 4.89 log cfu-equivalent for inoculated silages. There were fewer yeasts and aerobic stability was greater in inoculated silages (4.75 log cfu/g and 74 h of stability) than in untreated silages (5.55 log cfu/g and 46 h of stability). This study supports the effectiveness of L. buchneri 40788 on dairy farms.

Preservation of Phakopsora pachyrhizi uredospores

This study compared different temperatures and dormancy-reversion procedures for preservation of Phakopsora pachyrhizi uredospores. The storage temperatures tested were room temperature, 5 degrees C, -20 degrees C and -80 degrees C. Dehydrated and non-dehydrated uredospores were used, and evaluations for germination (%) and infectivity (no. of lesions/cm(2)) were made with fresh harvested spores and after 15, 29 76, 154 and 231 days of storage. The dormancy-reversion procedures evaluated were thermal shock (40 degrees C/5 min) followed or not by hydration (moist chamber,24 h). Uredospores stored at room temperature were viable only up to a month of storage, regardless of their hydration condition. Survival of uredospores increased with storage at lower temperatures. Dehydration of uredospores prior to storage increased their viability, mainly for uredospores stored at 5 degrees C, -20 degrees C and -80 degrees C. At 5 degrees C and -20 degrees C, dehydrated uredospores showed increases in viability of at least 47 and 127 days, respectively, compared to non-dehydrated spores. Uredospore germination and infectivity after storage for 231 days (7.7 months), could only be observed at -80 degrees C, for both hydration conditions. At this storage temperature, dehydrated and non-dehydrated uredospores exhibited 56 and 28% of germination at the end of the experiment, respectively. Storage at -80 degrees C also maintained uredospore infectivity, based upon levels of Infection frequency, for both hydration conditions. Among the dormancy-reversion treatments applied to spores stored at -80 degrees C, those involving hydration allowed recoveries of 85 to 92% of the initial germination.

Cattle depredation by puma (Puma concolor) and jaguar (Panthera onca) in central-western Brazil

In this study, data on cattle depredation by puma (Puma concolor) and jaguar (Panthera onca) were recorded for six years (1998 - 2003) in a cattle ranch in central-western Brazil. Depredation represented 18.9% of the overall cattle mortality, being predominant on calves. in biomass, kills represented 0.4% (63.8 kg/km(2)) of the ranch`s annual stock. in economic loss, kills represented 0.3% of the cattle stock value. Depredation was mainly associated with cattle`s age class and location along with the time of birth of calves. The proportion of pastures next to forest with depredation (n=33, 48.5%) was not distinguished to the proportion of pastures not bordering forest with depredation (n=35, 51.5%). However, the proportion of pastures next to forest with depredation represented 54% (n=33) of the 61 total pastures that were at least partially surrounded by forest patches or riparian forests that comprised eight continuum blocks of forest fragments of different sizes in the ranch and adjacent areas. No kills occurred in the central portion (main house) of the farm, close to the headquarters where the pastures not bordering forest. The distances of the kills in relation to areas of native forest was 1317.48 +/- 941.03 m. In order to reduce depredation, calves should be kept as far as possible from forest areas and concentrated cattle breeding and calving seasons should be encouraged. (c) 2007 Elsevier Ltd. All rights reserved.

Spatial patterns of soil attributes and components in a mangrove system in Southeast Brazil (Sao Paulo)

Purpose Among environmental factors governing innumerous processes that are active in estuarine environments, those of edaphic character have received special attention in recent studies. With the objectives of determining the spatial patterns of soil attributes and components across different mangrove forest landscapes and obtaining additional information on the cause-effect relationships between these variables and position within the estuary, we analyzed several soil attributes in 31 mangrove soil profiles from the state of So Paulo (Guaruja, Brazil). Materials and methods Soil samples were collected at low tide along two transects within the CrumahA(0) mangrove forest. Samples were analyzed to determine pH, Eh, salinity, and the percentages of sand, silt, clay, total organic carbon (TOC), and total S. Mineralogy of the clay fraction (< 2 mm) was also studied by X-ray diffraction analysis, and partitioning of solid-phase Fe was performed by sequential extraction. Results and discussion The results obtained indicate important differences in soil composition at different depths and landscape positions, causing variations in physicochemical parameters, clay mineralogy, TOC contents, and iron geochemistry. The results also indicate that physicochemical conditions may vary in terms of different local microtopographies. Soil salinity was determined by relative position in relation to flood tide and transition areas with highlands. The proportions of TOC and total S are conditioned by the sedimentation of organic matter derived from vegetation and by the prevailing redox conditions, which clearly favored intense sulfate reduction in the soils (similar to 80% of the total Fe is Fe-pyrite). Particle-size distribution is conditioned by erosive/deposition processes (present and past) and probably by the positioning of ancient and reworked sandy ridges. The existing physicochemical conditions appear to contribute to the synthesis (smectite) and transformation (kaolinite) of clay minerals. Conclusions The results demonstrate that the position of soils in the estuary greatly affects soil attributes. Differences occur even at small scales (meters), indicating that both edaphic (soil classification, soil mineralogy, and soil genesis) and environmental (contamination and carbon stock) studies should take such variability into account.

Physical and sensory characterization of coffee produced in the topoclimatic conditions at Jesuitas, Parana State (Brazil)

Climatic variations influence formation and maturation of coffee grains by altering their intrinsic characteristics, which call allow for several types of coffee qualities, including the potential for production of special coffee. This study was carried out to verify the effect of environmental conditions and crop cultivation on chemical composition and their consequences in cup quality of coffees from region of Jesuitas, Parana State. During the same crop season this study was accomplished (2002-2003), cup quality was evaluated among the producers in several coffee-growing municipalities in Parana State. It was observed that 86% of samples were classified simply as ""soft"" (smooth flavor) or ""hard"" (bolder flavor), and 14% were classified as rioysh/rio (strong unpleasant taste). The results concluded that the practices adopted by producers, who have collaborated with the study, reflected positively oil the final cup quality, when compared to the overall quality results in the State. The climatic conditions and practices of crop management and harvest ill the Jesuitas region made for bolder coffee with low acidity, comparable to high quality coffees produced in Brazil and abroad.

Nitrogen in common bean in no-tillage system over gramineae

An adequate supply of nitrogen is essential for high yield of common bean seeds; however, the responses to this nutrient in no-tillage systems can vary in function of the species and the amount of straw present. The aim of this research was to evaluate response of the common bean to N in no-tillage systems over maize, millet and Brachiaria brizantha crop residues. Three experiments were conducted, one for each gramineous species. The experimental design was a randomized block in a 5x2x2 factorial scheme, with five N doses (0, 30, 60, 90, 120 kg ha(-1)), in two distinct stadia during the vegetative development (3(rd) and 6(th) trifoliate leaf) and two common bean cultivars (IPR Juriti and Perola), with four replications. The IPR Juriti produced a greater number of pods per plant and showed lower mass per 100 seeds than Perola. It did not show variation in bean yield when the sidedressing N application was carried out in the 3(rd) or 6(th) trifoliate leaf stadia. Based on the obtained results, one concludes that the seed productivity of common beans increases linearly with N doses in a no-tillage system over maize residues.

Effectiveness of the standard evaluation method for hydraulic nozzles employed in stored grain protection trials

In stored grains, smaller depositions and great variation with respect to theoretical insecticide doses are frequently found. The objective of this work was to study the effectiveness of the standard method (ISO 5682/1-1996) employed to evaluate hydraulic nozzles used in stored corn and wheat grain protection experiments. The transversal volumetric distribution and droplet spectrum of a model TJ-60 8002EVS nozzle were determined in order to calibrate a spraying system for an application rate of 5 L/t and to obtain theoretical concentrations of 10 and 0.5 mg/kg of fenitrothion and esfenvalerate, respectively. After treatment, the corn and wheat grains were processed and deposition was analyzed by gas chromatography. The type of grain did not have any influence on insecticide deposition and was dependent upon insecticide only. The insecticide deposits on the grains only reached 42.1 and 38.2% of the intended theoretical values for fenitrothion and esfenvalerate concentrations, respectively. These results demonstrate the ineffectiveness of the standard evaluation method for hydraulic nozzles employed in stored grain protection experiments.

New eriophyoid mites (Acari: Prostigmata: Eriophyoidea) from banana and heliconia in Northeastern Brazil-two new genera and three new species

A new genus and new species of the mite family Eriophyidae (Phyllocoptinae), namely Cothrix erugata n. sp. et n. gen., is described from Heliconia stricta Huber (Heliconiaceae). In addition, one new genus and two new species of Diptilomiopidae, namely Rhyncadicrus asperulus n. sp. et n. gen. from banana, Musa acuminata Colla x Musa balbisiana Colla (genomic group AAB) (Musaceae) and Catarhinus granatus n. sp. from Heliconia bihai L., are described and illustrated. The mites were collected in the State of Pernambuco, Northeastern Brazil. All were vagrants on the lower leaf surfaces of their host plants and no visible damage symptoms were observed.