Calcium and Rhizodermal Differentiation in Primary Maize Roots

Rhizodermal differentiation of maize (Zea mays L. cv. LG 11) roots cultured in humid air was influenced by a pretreatment for 2 h in CaCl2 or CaSO4 solutions. This increased the number of hair-producing roots and the density of hairs. Ethylene glycol-bis-(β-aminoethyl ether)N,N'-tetraacetic acid (EGTA) was inhibitory. Root hairs emerged in the part of the cell nearer to the tip. Trichoblasts were shorter and elongated more slowly than atrichoblasts. The elongation of the lower part of the trichoblast was less than that of the upper par

Sex/gender bias in the management of chest pain in ambulatory care.

Cardiovascular diseases (CVD) are the main cause of death worldwide and despite a higher prevalence in men, mortality from CVD is higher among women. Few studies have assessed sex differences in chest pain management in ambulatory care. The objective of this post hoc analysis of data from a prospective cohort study was to assess sex differences in the management of chest pain in ambulatory care. We used data from the Thoracic Pain in Community cohort study that was realized in 58 primary care practices and one university ambulatory clinic in Switzerland. In total, 672 consecutive patients aged over 16 years attending a primary care practice or ambulatory care clinic with a complaint of chest pain were included between February and June 2001. Their mean age was 55.2 years and 52.5% were women. The main outcome was the proportion of patients referred to a cardiologist at 12 months follow-up. A panel of primary care physicians assessed the final diagnosis retained for chest pain at 12 months. The prevalence of chest pain of cardiovascular origin (n = 108, 16.1%) was similar for men and women (17.5% vs 14.8%, respectively, p = 0.4). Men with chest pain were 2.5 times more likely to be referred to a cardiologist than women (16.6% vs 7.4%, odds ratio: 2.49, 95% confidence interval: 1.52-4.09). After adjustment for the patients' age and cardiovascular disease risk factors, the estimates did not significantly change (odds ratio: 2.30, 95% confidence interval: 1.30-3.78). Although the same proportion of women and men present with a chest pain of cardiovascular origin in ambulatory care, there is a strong sex bias in their management. These data suggest that effort must be made to assure equity between men and women in medical care

Three-dimensional super-resolution microscopy of the inactive X chromosome territory reveals a collapse of its active nuclear compartment harboring distinct Xist RNA foci

Background: A Xist RNA decorated Barr body is the structural hallmark of the compacted inactive X territory in female mammals. Using super resolution three-dimensional structured illumination microscopy (3D-SIM) and quantitative image analysis, we compared its ultrastructure with active chromosome territories (CTs) in human and mouse somatic cells, and explored the spatio-temporal process of Barr body formation at onset of inactivation in early differentiating mouse embryonic stem cells (ESCs). Results: We demonstrate that all CTs are composed of structurally linked chromatin domain clusters (CDCs). In active CTs the periphery of CDCs harbors low-density chromatin enriched with transcriptionally competent markers, called the perichromatin region (PR). The PR borders on a contiguous channel system, the interchromatin compartment (IC), which starts at nuclear pores and pervades CTs. We propose that the PR and macromolecular complexes in IC channels together form the transcriptionally permissive active nuclear compartment (ANC). The Barr body differs from active CTs by a partially collapsed ANC with CDCs coming significantly closer together, although a rudimentary IC channel system connected to nuclear pores is maintained. Distinct Xist RNA foci, closely adjacent to the nuclear matrix scaffold attachment factor-A (SAF-A) localize throughout Xi along the rudimentary ANC. In early differentiating ESCs initial Xist RNA spreading precedes Barr body formation, which occurs concurrent with the subsequent exclusion of RNA polymerase II (RNAP II). Induction of a transgenic autosomal Xist RNA in a male ESC triggers the formation of an `autosomal Barr body' with less compacted chromatin and incomplete RNAP II exclusion. Conclusions: 3D-SIM provides experimental evidence for profound differences between the functional architecture of transcriptionally active CTs and the Barr body. Basic structural features of CT organization such as CDCs and IC channels are however still recognized, arguing against a uniform compaction of the Barr body at the nucleosome level. The localization of distinct Xist RNA foci at boundaries of the rudimentary ANC may be considered as snap-shots of a dynamic interaction with silenced genes. Enrichment of SAF-A within Xi territories and its close spatial association with Xist RNA suggests their cooperative function for structural organization of Xi

High resolution analysis of interphase chromosome domains.

Chromosome territories need to be well defined at high resolution before functional aspects of chromosome organization in interphase can be explored. To visualize chromosomes by electron microscopy (EM), the DNA of Chinese hamster fibroblasts was labeled in vivo with thymidine analogue BrdU. Labeled chromosomes were then segregated during several cell cycles to obtain nuclei containing only 2 to 3 labeled chromosomes. Subsequent immunocytochemical detection of BrdU allowed analysis by EM of chromosome territories and subchromosomal domains in well preserved nuclei. Our results provide the first high resolution visualization of chromosomes in interphase nuclei. We show that chromosome domains are either separated from one another by interchromatin space or are in close contact with no or little intermingling of their DNA. This demonstrates that, while chromosomes form discrete territories, chromatin of adjacent chromosomes may be in contact in limited regions, thus implying chromosome-chromosome interactions. Chromosomes are organized as condensed chromatin with dispersed chromatin extending into the interchromatin space that is largely devoid of DNA. The interchromatin space, which is known to be involved in various nuclear functions, forms interconnecting channels running through and around chromosome territories. Functional implications of this organization are discusse

Ultrastructural distribution of the death-domain-containing MyD88 protein in HeLa cells.

MyD88, a protein implicated in interleukin-1 signaling, was localized in HeLa cells transiently transfected with an epitope-tagged (flag) version of MyD88. Overexpression of MyD88 can induce apoptosis. We have analyzed the fine structural intracellular distribution of MyD88 using immunoelectron microscopy. MyD88 is localized to the nucleus and to the cytoplasm as revealed by immunofluorescence visualization. Ultrastructural immunocytochemistry shows that, in the cytoplasm, this protein is associated with fibrillar aggregates containing beta-actin. In the nucleus, MyD88 was found in fibrillar domains present only in cells not yet displaying morphological signs of apoptosis. These domains are not derived from nucleoli and do not constitute an accumulation site of splicing factors. We suggest that such structures could be involved in the formation of the apoptotic bodies and/or in the modification of the nuclear structure and of nucleocytoplasmic trafficking during apoptosis

Immunolocalization of glyoxysomal malate synthase from soybean cotyledons (Glycine max. L.)

Malate synthase (MS; EC 4.1.3.2), an enzyme specific to the glyoxylate cycle, was studied in cotyledons of dark-grown soybean (Glycine max L) seedlings with light and electron microscopy techniques. Immunogold localization confirmed biochemical evidence that MS from soybean is a glyoxysomal matrix enzyme

A new immunocytochemical technique for ultrastructural analysis of DNA replication in proliferating cells after application of two halogenated deoxyuridines.

We describe a colloidal gold immunolabeling technique for electron microscopy which allows one to differentially visualize portions of DNA replicated during different periods of S-phase. This was performed by incorporating two halogenated deoxyuridines (IdUrd and CldUrd) into Chinese hamster cells and, after cell processing, by detecting them with selected antibodies. This technique, using in particular appropriate blocking solutions and also Tris buffer with a high salt concentration and 1% Tween-20, prevents nonspecific background and crossreaction of both antibodies. Controls such as digestion with DNase and specific staining of DNA with osmium ammine show that labeling corresponds well to replicated DNA. Different patterns of labeling distribution, reflecting different periods of DNA replication during S-phase, were characterized. Cells in early S-phase display a diffuse pattern of labeling with many spots, whereas cells in late S-phase show labeling confined to larger domains, often at the periphery of the nucleus or associated with the nucleolus. The good correlation between our observations and previous double labeling results in immunofluorescence also proved the technique to be reliabl