Biomedical subjects

Nilce M Martinez-Rossi

Publications and source records attributed to Nilce M Martinez-Rossi.

7 recordsLinked to original sources

PubMed2007

Identification of genes displaying differential expression in the nuc-2 mutant strain of the mold Neurospora crassa grown under phosphate starvation.

Subtractive hybridization was used to isolate transcripts up-regulated in the nuc-2 mutant strain of Neurospora crassa grown under phosphate starvation. Following differential screening, 66 cDNA clones of the total enriched were screened in a second round by reverse Northern hybridization. The 17 cDNA candidates displaying visual positive differential expression were sequenced, and functional grouping identified putative proteins possibly involved in diverse cellular processes as, for example, protein synthesis, signal transduction mechanisms, and transport facilitation. Four of them, confirmed by both virtual and Northern blot analyses, revealed genes involved in the initiation of mRNA translation that are significantly up-regulated in the nuc-2 mutant strain, which may be relevant to a further understanding of the molecular events involved in the phosphorus sensing in N. crassa.

Ankyrin Repeat↗

PubMed2006

The pH signaling transcription factor PacC mediates the growth of Trichophyton rubrum on human nail in vitro.

We report here the isolation, molecular cloning and initial characterization of the Trichophytonrubrum pacC gene, which encodes a putative protein that is homologous to the PacC/Rim101p family of pH signaling transcription regulators. The promoter region of the T. rubrumpacC gene contains four recognition sites 5'-GCCAAG-3' for the PacC protein, suggesting that the transcription of this gene itself could be induced under alkaline growth conditions. The enhanced expression profile of the T. rubrumpacC gene in an alkaline environment was confirmed by Northern blotting analysis. We also report that the disruption of pacC gene decreased both the secretion of keratinolytic proteases and the ability of the mutant pacC-1 to grow on human nail fragments as the sole source of nutrition, i.e., growth of the dermatophyte T. rubrum appear to be related to molecular events which depend on the action of protein PacC.

Amino Acid Sequence↗

PubMed2006

Role of the ABC transporter TruMDR2 in terbinafine, 4-nitroquinoline N-oxide and ethidium bromide susceptibility in Trichophyton rubrum.

A single-copy gene, designated TruMDR2, encoding an ATP-binding cassette (ABC) transporter was cloned and sequenced from the dermatophyte Trichophyton rubrum. The ORF of TruMDR2 was 4048 nt and the deduced amino acid sequence showed high homology with ABC transporters involved in drug efflux in other fungi. The encoded ABC protein predicted 12 transmembrane segments (TMSs) and two almost identical nucleotide-binding domains (NBDs) arranged in two halves in a (TMS(6)-NBD)(2) configuration and could be classified as a member of the multidrug-resistance (MDR) class of ABC transporters. Northern blot analyses revealed an increased level of transcription of the TruMDR2 gene when mycelium was exposed to acriflavine, benomyl, ethidium bromide, ketoconazole, chloramphenicol, griseofulvin, fluconazole, imazalil, itraconazole, methotrexate, 4-nitroquinoline N-oxide (4NQO) or tioconazole. Disruption of the TruMDR2 gene rendered the mutant more sensitive to terbinafine, 4NQO and ethidium bromide than the control strain, suggesting that this transporter plays a role in modulating drug susceptibility in T. rubrum.

4-Nitroquinoline-1-oxide↗

PubMed2004

Identification and complete sequencing of novel human transcripts through the use of mouse orthologs and testis cDNA sequences.

The correct identification of all human genes, and their derived transcripts, has not yet been achieved, and it remains one of the major aims of the worldwide genomics community. Computational programs suggest the existence of 30,000 to 40,000 human genes. However, definitive gene identification can only be achieved by experimental approaches. We used two distinct methodologies, one based on the alignment of mouse orthologous sequences to the human genome, and another based on the construction of a high-quality human testis cDNA library, in an attempt to identify new human transcripts within the human genome sequence. We generated 47 complete human transcript sequences, comprising 27 unannotated and 20 annotated sequences. Eight of these transcripts are variants of previously known genes. These transcripts were characterized according to size, number of exons, and chromosomal localization, and a search for protein domains was undertaken based on their putative open reading frames. In silico expression analysis suggests that some of these transcripts are expressed at low levels and in a restricted set of tissues.

Amino Acid Sequence↗

PubMed2004

A transcript finishing initiative for closing gaps in the human transcriptome.

We report the results of a transcript finishing initiative, undertaken for the purpose of identifying and characterizing novel human transcripts, in which RT-PCR was used to bridge gaps between paired EST clusters, mapped against the genomic sequence. Each pair of EST clusters selected for experimental validation was designated a transcript finishing unit (TFU). A total of 489 TFUs were selected for validation, and an overall efficiency of 43.1% was achieved. We generated a total of 59,975 bp of transcribed sequences organized into 432 exons, contributing to the definition of the structure of 211 human transcripts. The structure of several transcripts reported here was confirmed during the course of this project, through the generation of their corresponding full-length cDNA sequences. Nevertheless, for 21% of the validated TFUs, a full-length cDNA sequence is not yet available in public databases, and the structure of 69.2% of these TFUs was not correctly predicted by computer programs. The TF strategy provides a significant contribution to the definition of the complete catalog of human genes and transcripts, because it appears to be particularly useful for identification of low abundance transcripts expressed in a restricted set of tissues as well as for the delineation of gene boundaries and alternatively spliced isoforms.

Alternative Splicing↗

PubMed2004

Terbinafine resistance mediated by salicylate 1-monooxygenase in Aspergillus nidulans.

Resistance to antifungal agents is a recurring and growing problem among patients with systemic fungal infections. UV-induced Aspergillus nidulans mutants resistant to terbinafine have been identified, and we report here the characterization of one such gene. A sib-selected, 6.6-kb genomic DNA fragment encodes a salicylate 1-monooxygenase (salA), and a fatty acid synthase subunit (fasC) confers terbinafine resistance upon transformation of a sensitive strain. Subfragments carrying salA but not fasC confer terbinafine resistance. salA is present as a single-copy gene on chromosome VI and encodes a protein of 473 amino acids that is homologous to salicylate 1-monooxygenase, a well-characterized naphthalene-degrading enzyme in bacteria. salA transcript accumulation analysis showed terbinafine-dependent induction in the wild type and the UV-induced mutant Terb7, as well as overexpression in a strain containing the salA subgenomic DNA fragment, probably due to the multicopy effect caused by the transformation event. Additional naphthalene degradation enzyme-coding genes are present in fungal genomes, suggesting that resistance could follow degradation of the naphthalene ring contained in terbinafine.

Antifungal Agents↗

PubMed2003

On the pBuM189 satellite DNA variability among South American populations of Drosophila buzzatii.

The pBuM189 satellite DNA was analysed in Drosophila buzzatii populations that cover most of the species distribution in South America. This satDNA consists of A + T-rich monomers of 189 bp and previous studies showed a fast rate of evolutionary change of this component of D. buzzatii genome. A total of 63 pBuM189 repetition units from 14 D. buzzatii populations (9 from Brazil and 5 from Argentina) were studied. The average nucleotide variability among the 63 repeats is 4.2 %. At least one repeat (Juan/4) seems to be part of another pBuM189 satDNA subfamily. The nucleotide alignment of all 63 repeats revealed no specific nucleotide substitutions, or indels, that could discriminate each population or groups of geographically close populations. Such lack of satDNA interpopulational differentiation is congruent with previous mtDNA data that indicate a high gene flow and very little population differentiation throughout most of the D. buzzatii distribution in South America. Gene flow might have been possible during glaciation events in the Pleistocene, such as the one occurred between 13,000 and 18,000 years ago, when D. buzzatii probably had a more continuous distribution than what is observed today.

Animals↗