Avaliação da genotoxicidade e mutagenicidade das águas dos rios Jaguari, Atibaia e Piracicaba, na região de influência da refinaria de Paulínia - SP

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação do potencial genotóxico e mutagênico de amostras de águas de recursos hídricos que recebem efluentes urbanos e industriais do pólo ceramista da cidade de Santa Gertrudes - SP

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Avaliação dos efeitos citotóxicos, genotóxicos e mutagênicos do BTEX, antes e após o processo de biorremediação por microrganismos, utilizando os sistemas teste de Allium cepa e cultura de células de mamífero

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Estudo do lodo gerado em reator biológico, pelo tratamento da água de produção do petróleo, no terminal marítimo Almirante Barroso, município de São Sebastião, SP visando sua disposição final

Pós-graduação em Ciências Biológicas (Microbiologia Aplicada) - IBRC

Avaliação do potencial mutagênico e bioacumulador de metais pesados de Baccharis trimera Less e Equisetum hyemale L

Pós-graduação em Biociências - FCLAS

Genotoxic activity and toxicity of Baccharis trimera Less. regarding the bioaccumulation of heavy metals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phytotoxicity of Solanum aculeatissimum Jacq: leaves extract

The objective of this study was to evaluate the phytotoxicity of Solanum aculeatissimum Jacq. leaves ethanolic extract in seeds germination, development and fixation of Lactuca sativa seedlings. The same study also aimed to assess the mitotic index of lettuce roots meristematic cells, quantification of phenols and total flavonoids and triage by mean of phytochemical testing of the main secondary metabolites classes. Bioassays of germination, development of root and hypocotyl were carried out in Petri dishes using achenes of Lactuca sativa L. cv. 'Grand Rapids' (lettuce). Concomitantly, were evaluated the physico-chemical characteristics (pH, osmotic potential and electrical conductivity), mitotic index, quantification of total phenols and flavonoids and determination of phytochemical profile of the treatments extract. The results obtained in the bioassays demonstrate that the ethanol extract of S. aculeatissimuma presents phytotoxic potential in the development of lettuce seedlings, given that the concentration of 20 mg/ml showed greater inhibition (41% of germination). The extract contains significant amounts of antioxidants, total flavonoid and phenols, where the concentration 1000µg/mL showed higher values (86.50%). Furthermore, it was possible to observe the presence of compounds with allelopathic activity in the phytochemical screening test as coumarins, tannins, terpenes, flavonoids and alkaloids. Given the above it is clear that the ethanolic extract of S. aculeatissimum presents allelopathic substances with phytotoxic activity that can affect the germination and development of other plant species in their natural environment.

Diferenciação de laticíferos articulados em plantas de Tabernaemontana catharinensis (Apocynaceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Meristem-Specific Suppression of Mitosis and a Global Switch in Gene Expression in the Root Cap of Pea by Endogenous Signals1

Two functionally distinct sets of meristematic cells exist within root tips of pea (Pisum sativum): the root apical meristem, which gives rise to the body of the root; and the root cap meristem, which gives rise to cells that differentiate progressively through the cap and separate ultimately from its periphery as border cells. When a specific number of border cells has accumulated on the root cap periphery, mitosis within the root cap meristem, but not the apical meristem, is suppressed. When border cells are removed by immersion of the root tip in water, a transient induction of mitosis in the root cap meristem can be detected starting within 5 min. A corresponding switch in gene expression throughout the root cap occurs in parallel with the increase in mitosis, and new border cells begin to separate from the root cap periphery within 1 h. The induction of renewed border cell production is inhibited by incubating root tips in extracellular material released from border cells. The results are consistent with the hypothesis that operation of the root cap meristem and consequent turnover of the root cap is self-regulated by a signal from border cells.

Characterization of a Maize Tonoplast Aquaporin Expressed in Zones of Cell Division and Elongation1

We studied aquaporins in maize (Zea mays), an important crop in which numerous studies on plant water relations have been carried out. A maize cDNA, ZmTIP1, was isolated by reverse transcription-coupled PCR using conserved motifs from plant aquaporins. The derived amino acid sequence of ZmTIP1 shows 76% sequence identity with the tonoplast aquaporin γ-TIP (tonoplast intrinsic protein) from Arabidopsis. Expression of ZmTIP1 in Xenopus laevis oocytes showed that it increased the osmotic water permeability of oocytes 5-fold; this water transport was inhibited by mercuric chloride. A cross-reacting antiserum made against bean α-TIP was used for immunocytochemical localization of ZmTIP1. These results indicate that this and/or other aquaporins is abundantly present in the small vacuoles of meristematic cells. Northern analysis demonstrated that ZmTIP1 is expressed in all plant organs. In situ hybridization showed a high ZmTIP1 expression in meristems and zones of cell enlargement: tips of primary and lateral roots, leaf primordia, and male and female inflorescence meristems. The high ZmTIP1 expression in meristems and expanding cells suggests that ZmTIP1 is needed (a) for vacuole biogenesis and (b) to support the rapid influx of water into vacuoles during cell expansion.

Karyotype and genome size in Euterpe Mart. (Arecaceae) species.

Euterpe (Martius, 1823), a genus from Central and South America, has species with high economic importance in Brazil, because of their palm heart and fruits, known as açaí berries. Breeding programs have been conducted to increase yield and establish cultivation systems to replace the extraction of wild material. These programs need basic information about the genome of these species to better explore the available genetic variability. The aim of this study was to compare E. edulis (Martius, 1824), E. oleracea (Martius, 1824) and E. precatoria (Martius, 1842), with regard to karyotype, type of interphase nucleus and nuclear DNA amount. Metaphase chromosomes and interphase nuclei from root tip meristematic cells were obtained by the squashing technique and solid stained for microscope analysis. The DNA amount was estimated by flow cytometry. There were previous reports on the chromosome number of E. edulis and E. oleracea, but chromosome morphology of these two species and the whole karyotype of E. precatoria are reported for the first time. The species have 2n=36, a number considered as a pleisomorphic feature in Arecoideae since the modern species, according to floral morphology, have the lowest chromosome number (2n=28 and 2n=30). The three Euterpe species also have the same type of interphase nuclei, classified as semi-reticulate. The species differed on karyotypic formulas, on localization of secondary constriction and genome size. The data suggest that the main forces driving Euterpe karyotype evolution were structural rearrangements, such as inversions and translocations that alter chromosome morphology, and either deletion or amplification that led to changes in chromosome size.

The orf13 T-DNA gene of Agrobacterium rhizogenes confers meristematic competence to differentiated cells

Plant infections by the soil bacterium Agrobacterium rhizogenes result in neoplastic disease with the formation of hairy roots at the site of infection. Expression of a set of oncogenes residing on the stably integrated T-DNA is responsible for the disease symptoms. Besides the rol (root locus) genes, which are essential for the formation of hairy roots, the open reading frame orf13 mediates cytokinin-like effects, suggesting an interaction with hormone signaling pathways. Here we show that ORF13 induced ectopic expression of KNOX (KNOTTED1-like homeobox) class transcription factors, as well as of several genes involved in cell cycle control in tomato (Lycopersicon esculentum). ORF13 has a retinoblastoma (RB)-binding motif and interacted with maize (Zea mays) RB in vitro, whereas ORF13, bearing a point mutation in the RB-binding motif (ORF13*), did not. Increased cell divisions in the vegetative shoot apical meristem and accelerated formation of leaf primordia were observed in plants expressing orf13, whereas the expression of orf13* had no influence on cell division rates in the shoot apical meristem, suggesting a role of RB in the regulation of the cell cycle in meristematic tissues. On the other hand, ectopic expression of LeT6 was not dependent on a functional RB-binding motif. Hormone homeostasis was only altered in explants of leaves, whereas in the root no effects were observed. We suggest that ORF13 confers meristematic competence to cells infected by A. rhizogenes by inducing the expression of KNOX genes and promotes the transition of infected cells from the G1 to the S phase by binding to RB.

Induction of mitotic and chromosomal abnormalities on Allium cepa cells by pesticides imidacloprid and sulfentrazone and the mixture of them

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Analysis of the genotoxic potential of low concentrations of Malathion on the Allium cepa cells and rat hepatoma tissue culture

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The meristematic activity of the endodermis and the pericycle and its role in the primary thickening of stems in monocotyledonous plants

Background: It had long been thought that a lateral meristem, the so-called primary thickening meristem (PTM) was responsible for stem thickening in monocotyledons. Recent work has shown that primary thickening in the stems of monocotyledons is due to the meristematic activity of both the endodermis and the pericycle. Aims: The aim of this work is to answer a set of questions about the developmental anatomy of monocotyledonous plants: (1) Do the stem apices of monocots have a special meristematic tissue, the PTM? (2) Are the primary tissues of the stem the same as those of the root? (3) Is there good evidence for the formation of both the cortex and the vascular tissue from a single meristem, the PTM, in the shoot and from two distinguishable meristems in the root? (4) If the PTM forms only the cortex, what kind of meristem forms the vascular tissue? Methods: Light microscopy was used to examine stem and root anatomy in 16 species from 10 monocotyledonous families. Results: It was observed that radially aligned cortical cells extend outwards from endodermal initial cells in the cortex of the roots and the stems in all the species. The radial gradation in size observed indicates that the cortical cells are derivatives of a meristematic endodermis. In addition, perfect continuity was observed between the endodermis of the root and that of the stem. Meristematic activity in the pericycle gives rise to cauline vascular bundles composed of metaxylem and metaphloem. Conclusion: No evidence was obtained for the existence in monocotyledons of a PTM. Monocotyledons appear to resemble other vascular plants in this respect.