No abstract

The cellular and subcellular localization of endogenous nitric oxide (NO . ) in leaves from young and senescent pea (Pisum sativum) plants was studied. Confocal laser scanning microscopy analysis of pea leaf sections with the fluorescent probe 4,5-diaminofluorescein diacetate revealed that endogenous NO. was mainly present in vascular tissues (xylem and phloem).Green fluorescence spots were also detected in the epidermal cells, palisade and spongy mesophyll cells, and guard cells. ) is a widespread intracellular and intercellular messenger with a broad spectrum of regulatory functions in many physiological processes (Moncada et al., 1991;Ignarro, 2002;Wendehenne et al., 2001;Lamattina et al., 2003;Neill et al., 2003;del Río et al., 2004). In recent years, NO. was reported to be involved in many key physiological processes of plants, such as ethylene emission (Leshem and Haramaty, 1996), response to drought (Leshem, 1996), disease resistance (Delledonne et al., 1998(Delledonne et al., , 2001Durner et al., 1998;Clarke et al., 2000), growth and cell proliferation (Ribeiro et al., 1999), maturation and senescence (Leshem et al., 1998), apoptosis/programmed cell death (Magalhaes et al., 1999;Clarke et al., 2000;Pedroso and Durzan, 2000;Pedroso et al., 2000a;Zhang et al., 2003), and stomatal closure Lamattina, 2001, 2002;Neill et al., 2002a;García-Mata et al., 2003).The application of exogenous NO . to plants has been used as a tool to study how this molecule affects some physiological processes, such as inhibition of certain enzyme activities (Clark et al., 2000;Navarre et al., 2000), cell wall lignification (Ferrer and Ros Barceló , 1999) In animal systems, a considerable attention is being dedicated to this molecule and the enzyme responsible for its production from L-Arg, nitric oxide synthase (NOS; EC 1.14. 13.39;Hemmens and Mayer, 1998; Alderton et al., 2001). On the contrary, in plants comparatively much less is known on the source of NO . production (Neill et al., 2003;Wendehenne et al., 2003;del Río et al., 2004 Article, publication date, and citation information can be found at www.plantphysiol.org/cgi

During reproductive life, the human endometrium undergoes around 480 cycles of growth, breakdown and regeneration should pregnancy not be achieved. This outstanding regenerative capacity is the basis for women's cycling and its dysfunction may be involved in the etiology of pathological disorders. Therefore, the human endometrial tissue must rely on a remarkable endometrial somatic stem cells (SSC) population. Here we explore the hypothesis that human endometrial side population (SP) cells correspond to somatic stem cells. We isolated, identified and characterized the SP corresponding to the stromal and epithelial compartments using endometrial SP genes signature, immunophenotyping and characteristic telomerase pattern. We analyzed the clonogenic activity of SP cells under hypoxic conditions and the differentiation capacity in vitro to adipogenic and osteogenic lineages. Finally, we demonstrated the functional capability of endometrial SP to develop human endometrium after subcutaneous injection in NOD-SCID mice. Briefly, SP cells of human endometrium from epithelial and stromal compartments display genotypic, phenotypic and functional features of SSC.

Spinal cord injury (SCI) triggers a multitude of pathophysiological events that are tightly regulated by the expression levels of specific genes. Recent studies suggest that changes in gene expression following neural injury can result from the dysregulation of microRNAs, short non-coding RNA molecules that repress the translation of target mRNA. To understand the mechanisms underlying gene alterations following SCI, we analyzed the microRNA expression patterns at different time points following rat spinal cord injury.The microarray data reveal the induction of a specific microRNA expression pattern following moderate contusive SCI that is characterized by a marked increase in the number of down-regulated microRNAs, especially at 7 days after injury. MicroRNA downregulation is paralleled by mRNA upregulation, strongly suggesting that microRNAs regulate transcriptional changes following injury. Bioinformatic analyses indicate that changes in microRNA expression affect key processes in SCI physiopathology, including inflammation and apoptosis. MicroRNA expression changes appear to be influenced by an invasion of immune cells at the injury area and, more importantly, by changes in microRNA expression specific to spinal cord cells. Comparisons with previous data suggest that although microRNA expression patterns in the spinal cord are broadly similar among vertebrates, the results of studies assessing SCI are much less congruent and may depend on injury severity. The results of the present study demonstrate that moderate spinal cord injury induces an extended microRNA downregulation paralleled by an increase in mRNA expression that affects key processes in the pathophysiology of this injury.