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Rui Pires Martins

Publications and source records attributed to Rui Pires Martins.

4 recordsLinked to original sources
PubMed2005

RNA in human sperm.

We have yet to develop a fundamental understanding of the molecular complexities of human spermatozoa. This encompasses the unique packaging and structure of the sperm genome along with their paternally derived RNAs in preparation for their delivery to the egg. The diversity of these transcripts is vast, including several anti-sense molecules resembling known regulatory micro-RNAs. The field is still grasping with its delivery to the oocyte at fertilization and possible significance. It remains tempting to analogize them to maternally-derived transcripts active in early embryo patterning. Irrespective of their role in the embryo, their use as a means to assess male factor infertility is promising.

DNA↗
PubMed2004

Nuclear matrix interactions at the human protamine domain: a working model of potentiation.

The compact eukaryotic genome must be selectively opened to grant trans-factor access to cis-regulatory elements to overcome the primary barrier to gene transcription. The mechanism that governs the selective opening of chromatin domains (i.e. potentiation) remains poorly understood. In the absence of a well defined locus control region, the nuclear matrix is considered the primary candidate regulating the opening of the multigenic PRM1 --> PRM2 --> TNP2 human protamine domain. To directly examine its role, four lines of transgenic mice with different configurations of flanking nuclear matrix attachment regions (MARs) encompassing the protamine domain were created. We show that upon removal of the MARs, the locus becomes subject to position effects. The 3' MAR alone may be sufficient to protect against silencing. In concert, the MARs bounding this domain likely synergize to regulate the expression of the various members of this gene cluster. Interestingly, the MARs may convey a selective reproductive advantage, such that constructs bearing both 5' and 3' MARs are passed to their offspring with greater frequency. Thus, the MARs bounding the PRM1 --> PRM2 --> TNP2 protamine domain have many and varied functions.

Animals↗
PubMed2003

Nuclear matrix association of the human beta-globin locus utilizing a novel approach to quantitative real-time PCR.

The human beta-globin locus is home to five genes that are regulated in a tissue-specific and developmental stage-specific manner. While the exact mode of expression remains somewhat enigmatic, a significant effort has been focused at the locus control region (LCR). The LCR is marked by five DNase I-hypersensitive sites (HS) approximately 15 kb upstream of the epsilon-globin gene. Nuclear matrix-associated regions (MARs) organize chromatin into functional domains and at least one of the HS appears bound to the nuclear matrix. We have employed an in vivo based PCR MAR assay to investigate the role of MAR-mediated regulation of the beta-globin locus. This was facilitated with a novel reaction efficiency based quantitative real-time PCR analysis software tool, Target Analysis Quantification. Using a log-linear regression strategy, discordances were eliminated. This allowed us to reliably estimate the relative amount of initial template associated with the nuclear matrix at 15 unique regions spanning the beta-globin locus in both non-expressing and expressing cell lines. A dynamic association dependent on expression status was revealed both at the LCR/5'HS region and within the second intron of the beta-globin gene. These results provide the first evidence that nuclear matrix association dynamically mediates the looping of the beta-globin locus to achieve transcriptional control.

Cell Line↗