15 research outputs found

    Viabilidade de ovos de Aedes aegypti (Diptera, Culicidae) em diferentes condições de armazenamento em Manaus, Amazonas, Brasil

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    The viability of Aedes aegypti eggs was assessed in the Amazon region. The eggs were maintained under different conditions: indoors (insectarium) and outdoors (natural environment), as well as in different storage types (plastic cup, paper envelope, plastic bag) for different days. Egg viability was measured as the mean of hatchings observed from egg-bearing sheets of filter paper immersed in water, using three sheets randomly selected from each storage type and at both sites. There were significant differences in the viability of Ae. aegypti eggs with respect to the location (F=30.40; DF=1; P<0.0001), storage type (F=17.66; DF=2; P<0.0001), and time of storage (F=49.56; DF=9; P<0.0001). The interaction between storage site versus storage type was also significant (F=15.96; DF=2; P<0.0001). A higher hatching mean was observed for the eggs kept in the insectarium than for those outdoors (32.38 versus 7.46). Hatching rates of egg batches stored for 12 to 61 days ranged between 84 and 90%. A reduction was observed between 89 and 118 days, with values of 63 and 48%, respectively. With respect to type of storage, mean egg hatching was higher for the eggs in plastic cups (44.46). It was concluded that the viability of the eggs of Ae. aegypti in the Amazon region remains high up to 4 months, after which it declines drastically, although in this study hatching occurred for up to 8 months in very low percentages. © 2017, Instituto Internacional de Ecologia. All rights reserved

    Analysis of genes differentially expressed during potato tuber life cycle and isolation of their promoter regions

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    The potato tuber life cycle involves several developmental stages including tuberisation, tuber growth, dormancy and sprouting. Gene expression during the potato tuber life cycle has been monitored using a RNA fingerprinting technique termed cDNA-AFLP The expression profile of the nearly 2000 transcript derived fragments (TDFs) was analysed and general conclusions concerning the different stages of tuber life cycle and tissue specificity were drawn. Comparison of 116 TDFs isolated and sequenced to the NCBI databases indicated that most of the genes expressed during tuber life cycle are involved in defence, stress, storage and signal transduction pathways. In order to identify time and tissue specific regulatory elements, the TDFs were further screened for their time and tissue specific expression and the putative promoters corresponding to the twelve differentially expressed TDFs were isolated. Comparison of the 12 upstream sequences to all described cis-acting elements resulted in the identification of 12 know cis-acting elements: two general cis-elements, one enhancer and nine specific boxes. These specific cis-elements have been characterised in other plant species and they respond to light, sugars and hormones such as gibberellins, auxins and abscisic acid (ABA). All these environmental factors play an important role during the potato tuber life cycle. (C) 2003 Elsevier Ireland Ltd. All rights reserved

    Isolation and functional characterization of a stolon specific promoter from potato (Solanum tuberosum L.)

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    In the search for time- and tissue-specific promoters an RNA fingerprinting technique called cDNA-AFLP was used. A transcript derived fragment (TDF511) was isolated which showed high similarity to alcohol dehydrogenases. The gene corresponding to this TDF, named Stgan, is likely to be involved in biosynthesis or breakdown of compounds affecting gibberellic acid (GA) levels in the plant [Plant J. 25(6) (2001) 595]. In this article the isolation and characterization of a Stgan promoter region is reported. The promoter region of this gene was fused to a reporter gene encoding ß-glucuronidase (GUS) and introduced in potato plants. GUS staining was detected uniquely in stolon tips and nodes. RNA in situ hybridization experiments revealed that this gene was specifically expressed in parenchyma cells, in the stolon cortex. Comparison of this promoter sequence with several promoter databases resulted in the identification of several potential binding sites for transcription factors. From the in vitro-culture experiments Stgan transcription appears to be induced by long days, sucrose and different hormones such as gibberellic acid, ancymidol, ethylene and cytokinins

    Analysis of genes differentially expressed during potato tuber life cycle and isolation of their promoter regions

    No full text
    The potato tuber life cycle involves several developmental stages including tuberisation, tuber growth, dormancy and sprouting. Gene expression during the potato tuber life cycle has been monitored using a RNA fingerprinting technique termed cDNA-AFLP The expression profile of the nearly 2000 transcript derived fragments (TDFs) was analysed and general conclusions concerning the different stages of tuber life cycle and tissue specificity were drawn. Comparison of 116 TDFs isolated and sequenced to the NCBI databases indicated that most of the genes expressed during tuber life cycle are involved in defence, stress, storage and signal transduction pathways. In order to identify time and tissue specific regulatory elements, the TDFs were further screened for their time and tissue specific expression and the putative promoters corresponding to the twelve differentially expressed TDFs were isolated. Comparison of the 12 upstream sequences to all described cis-acting elements resulted in the identification of 12 know cis-acting elements: two general cis-elements, one enhancer and nine specific boxes. These specific cis-elements have been characterised in other plant species and they respond to light, sugars and hormones such as gibberellins, auxins and abscisic acid (ABA). All these environmental factors play an important role during the potato tuber life cycle. (C) 2003 Elsevier Ireland Ltd. All rights reserved

    Continuous monitoring of mechanical properties of plantar soft tissue for diabetic patients using wearable ultrasonic and force sensors

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    Characterizing plantar soft tissue mechanical properties is essential to fully understand the potential for ulcer formation in diabetic patients. Ulcers initiate in the under layers of foot where soft tissues become stiffer. If changes in soft tissue stiffness can be detected early, foot ulcer formation may be prevented. Also, monitoring soft tissue mechanical properties could be beneficial for prosthetic and orthotic fitting, sport performance monitoring, and injury prevention and detection. This paper presents a method, using wearable ultrasonic and force sensors, for continuous monitoring of plantar soft tissue stiffness at the heel. With this method, simultaneous measurement of pressure and tissue displacement at the heel was performed and pressure-displacement curves were obtained while the person was stepping. This achievement establishes a basis for future research to assess mechanical properties of plantar soft tissues in real-time for foot ulcer screening

    A potato tuber-expressed mNRA with homology to steroid dehydrogenases affects gibberellin levels and plant development

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    Using cDNA-AFLP RNA fingerprinting throughout potato tuber development, we have isolated a transcript-derived fragment (TDF511) with strong homology to plant steroid dehydrogenases. During in vitro tuberization, the abundance profile of the TDF shows close correlation to the process of tuber formation. However, when tuberization is inhibited by the addition of gibberellins (GAs) to the growth medium, the appearance of TDF511 in the fingerprint is delayed, then steadily increases in intensity during later stages of development. TDF511 was used to isolate the corresponding cDNA (CB12). The DNA and deduced amino-acid sequences of the cDNA show high homology to a fruit-ripening gene from tomato, a series of steroid dehydrogenases, and the maize Ts2 gene. A section of the cDNA was cloned in antisense orientation behind a 35S CaMV promoter and transformed into potato. Transgenic plants expressing the antisense gene showed significantly earlier emergence, an increase in height, and longer tuber shape. In vitro tuberization experiments reveal extended stolen lengths in comparison to the controls. The analysis of endogenous GA levels showed that the transgenic antisense plants have elevated levels of biologically active GAs and their respective precursors. We propose that this gene plays a role in the metabolism of plant-growth substances important for tuber life cycle and plant development

    Origin of increased terrigenous supply to the NE South American continental margin during Heinrich Stadial 1 and the Younger Dryas

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    International audienceWe investigate the redistribution of terrigenous materials in the northeastern (NE) South American continental margin during slowdown events of the Atlantic Meridional Overturning Circulation (AMOC). The compilation of stratigraphic data from 108 marine sediment cores collected across the western tropical Atlantic shows an extreme rise in sedimentation rates off the Parnaíba River mouth (about 2°S) during Heinrich Stadial 1 (HS1, 18–15 ka). Sediment core GeoB16206-1, raised offshore the Parnaíba River mouth, documents relatively constant 143Nd/144Nd values (expressed as εNd(0)) throughout the last 30 ka. Whereas the homogeneous εNd(0) data support the input of fluvial sediments by the Parnaíba River from the same source area directly onshore, the increases in Fe/Ca, Al/Si and Rb/Sr during HS1 indicate a marked intensification of fluvial erosion in the Parnaíba River drainage basin. In contrast, the εNd(0) values from sediment core GeoB16224-1 collected off French Guiana (about 7°N) suggest Amazon-sourced materials within the last 30 ka. We attribute the extremely high volume of terrigenous sediments deposited offshore the Parnaíba River mouth during HS1 to (i) an enhanced precipitation in the catchment region and (ii) a reduced North Brazil Current, which are both associated with a weakened AMOC
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