MicroRNAs (miRNAs) are short (∼22 nt) non-coding regulatory RNAs that control gene expression at the post-transcriptional level. Deregulation of miRNA expression has been discovered in a wide variety of tumours and it is now clear that they contribute to cancer development and progression. Cervical cancer is one of the most common cancers in women worldwide and there is a strong need for a non-invasive, fast and efficient method to diagnose the disease. We investigated miRNA expression profiles in cervical cancer using a microarray platform containing probes for mature miRNAs. We have evaluated miRNA expression profiles of a heterogeneous set of cervical tissues from 25 different patients. This set included 19 normal cervical tissues, 4 squamous cell carcinoma, 5 high-grade squamous intraepithelial lesion (HSIL) and 9 low-grade squamous intraepithelial lesion (LSIL) samples. We observed high variability in miRNA expression especially among normal cervical samples, which prevented us from obtaining a unique miRNA expression signature for this tumour type. However, deregulated miRNAs were identified in malignant and pre-malignant cervical tissues after tackling the high expression variability observed. We were also able to identify putative target genes of relevant candidate miRNAs. Our results show that miRNA expression shows natural variability among human samples, which complicates miRNA data profiling analysis. However, such expression noise can be filtered and does not prevent the identification of deregulated miRNAs that play a role in the malignant transformation of cervical squamous cells. Deregulated miRNAs highlight new candidate gene targets allowing for a better understanding of the molecular mechanism underlying the development of this tumour type.

No abstract

Increasing the yield of soybean is a challenge to humankind dependent on several management practices, such as fertilizing and weed control. While glyphosate contributes to controlling weeds, it can interfere with spray mixture stability and, supposedly, complex with micronutrients within the plant tissue. This study investigated the effects of glyphosate on soybean foliar uptake and transport of Mn supplied as MnSO4, MnHPO3, Mn-ethylenediamine tetraacetic acid (EDTA), and MnCO3. These fertilizers induced ultrastructural changes in the leaf cuticle, regardless of the glyphosate mixture. Except for MnCO3, all tested sources increased the Mn content in the petiole. The mixture of glyphosate impaired Mn transport from MnSO4 and MnHPO3, but no evidence of Mn–glyphosate complexation within the plant was found. Manganese is rather transported in a similar chemical environment regardless of the source, except for Mn-EDTA, which was absorbed and transported in its pristine form. Interferences of glyphosate seem to be related to complexations in the tank mixture rather than affecting nutrients’ metabolism.

The genes transcribed by RNA polymerase (pol)111 can be placed into four distinct groups based on the nature and position of their promoter elements. In the higher eukaryotes equivalent genes usually belong to the same sub-type of pol Hi promoters and there are few examples of genes which have changed promoter type during evolution. In this work we demonstrate that the promoter of the Arabidopsis thaliana 7SL RNA gene is located upstream of the coding region and is identical to the promoters of pol III-specific plant U-small nuclear RNA (U-snRNA) genes. Sequence analysis of two different 7SL genes from A.thaliana revealed that both genes contain two sequence elements in their 5' flanking regions identical in sequence and position to the highly conserved USE and TATA elements of the pol III-transcribed plant U-snRNA genes. Mutational analysis of these elements in the At7SL-2 gene indicates that the USE and TATA elements are both necessary and account for >90°% of the transcriptional activity of this gene in transfected plant protoplasts. Within the coding region of both genes there is a sequence element which is a 10/11 nt match to the consensus B-box element of tRNA genes, however, this element is not important for gene activity. These findings distinguish the plant genes from the human 7SL gene, which has both intemal and upstream promoter elements and its upstream elements are different from those found in the human U-snRNA genes.

Austropuccinia psidii, the causal agent of myrtle rust, is a biotrophic pathogen whose growth and development depends on the host tissues. The uredospores of A. psidii infect Eucalyptus by engaging in close contact with the host surface and interacting with the leaf cuticle that provides important chemical and physical signals to trigger the infection process. In this study, the cuticular waxes of Eucalyptus spp. were analyzed to determine their composition or structure and correlation with susceptibility/resistance to A. psidii. Twenty-one Eucalyptus spp. in the field were classified as resistant or susceptible. The resistance/susceptibility level of six Eucalyptus spp. were validated in controlled conditions using qPCR, revealing that the pathogen can germinate on the eucalyptus surface of some species without multiplying in the host. CG-TOF-MS analysis detected 26 compounds in the Eucalyptus spp. cuticle and led to the discovery of the role of hexadecanoic acid in the susceptibility of Eucalyptus grandis and Eucalyptus phaeotricha to A. psidii. We characterized the epicuticular wax morphology of the six previously selected Eucalyptus spp. using scanning electron microscopy and observed different behavior in A. psidii germination during host infection. It was found a correlation of epicuticular morphology on the resistance to A. psidii. However, in this study, we provide the first report of considerable interspecific variation in Eucalyptus spp. on the susceptibility to A. psidii and its correlation with cuticular waxes chemical compounds that seem to play a synergistic role as a preformed defense mechanism.

In Brazil, citrus black spot (CBS) caused by Guignardia citricarpa is a major disease that has different symptoms on fruit. In this study, fruit of Citrus sinensis infected by G. citricarpa and showing the symptoms false melanosis, freckle spot and hard spot were cross-sectioned and analysed anatomically and histochemically by light microscopy. Immunohistological assays were performed. All symptoms were accompanied by a thickening of the cuticle. False melanosis lesions did not contain pycnidia and remained restricted to the epicarp or to the first layers of the mesocarp. The stomata in this type of lesion showed phenolic compounds in the guard cells and in the sub-stomatal chamber. In some samples, the guard cells and their surrounding cells lysed, and a wound meristem began to form underneath them. Freckle spot and hard spot lesions had very similar histological alterations to the epicarp and mesocarp, but in our samples only hard spot lesions contained pycnidia. Both of these symptoms were accompanied by protein inclusions. Epidermal and sub-epidermal cells located in the oil-gland region were obliterated, causing alterations in these structures. All symptoms had regions that stained strongly for lipids and phenols.

O objetivo deste trabalho foi apresentar a descrição anatômica dos tecidos lesionados pelo Citrus leprosis virus do tipo citoplasmático (CiLV-C), em ramos e folhas de laranjeira-doce (Citrus sinensis (L.) Osbeck) 'Pêra', e fornecer dados para a compreensão das interações entre o vírus e a planta hospedeira. Tecidos que apresentavam lesões foram seccionados em micrótomo rotativo (5-7 µm de espessura) e, posteriormente, as lâminas foram coradas e montadas em resina sintética. Nas análises realizadas no microscópio eletrônico de varredura, as amostras, depois de fixadas, foram imersas em glicerina 30% e, em seguida, criofraturadas, desidratadas em série etílica, secadas ao ponto crítico de CO2, e cobertas com uma delgada camada de ouro. As lesões foliares se iniciaram como pontuações necróticas, envolvidas por halos cloróticos que limitam o crescimento da lesão. Nos ramos, ocorreram dois tipos de lesões com fendas. Na região da fenda, houve intensa hiperplasia do parênquima cortical e floemático, que promoveu a obliteração das células condutoras do floema. A formação de ductos gomosos traumáticos nas lesões caulinares foi descrita. As alterações verificadas no floema podem explicar porque o vírus torna-se não-sistêmico.

X-ray fluorescence spectroscopy presents a unique capability to probe the elemental content of plants in vivo, besides combination with other non-destructive tools to assess physiological processes.