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81.
Three maize root-specific genes are not correctly expressed in regenerated caps in the absence of the quiescent center 总被引:6,自引:0,他引:6
The quiescent center is viewed as an architectural template in the root apical meristem of all angiosperm and gymnosperm
root tips. In roots of Arabidopsis thaliana (L.) Heynh., the quiescent center inhibits differentiation of contacting initial cells and maintains the surrounding initial
cells as stem cells. Here, the role of the quiescent center in the development of the maize (Zea mays L.) root cap has been further explored. Three maize root-specific genes were identified. Two of these were exclusively expressed
in the root cap and one of them encoded a GDP-mannose-4,6-dehydratase. Most likely these two genes are structural, tissue-specific
markers of the cap. The third gene, a putative glycine-rich cell wall protein, was expressed in the cap and in the root epidermis
and, conceivably is a positional marker of the cap. Microsurgical and molecular data indicate that the quiescent center and
cap initials may regulate the positional and structural expression of these genes in the cap and thereby control root cap
development.
Received: 22 September 1999 / Accepted: 9 November 1999 相似文献
82.
Relationship between T-wave amplitude and oxygen pulse in guinea pigs in hyperbaric helium and hydrogen 总被引:1,自引:0,他引:1
Kayar Susan R.; Parker Erich C.; Aukhert Eugenia O. 《Journal of applied physiology》1998,85(3):798-806
Diving isknown to induce a change in the amplitude of the T wave(ATw) ofelectrocardiograms, but it is unknown whether this is linked to achange in cardiovascular performance. We analyzed ATw in guinea pigs at 10-60atm and 25-36°C, breathing 2%O2 in either helium (heliox;n = 10) or hydrogen (hydrox;n = 9) for 1 h at each pressure. Coretemperature and electrocardiograms were detected by using implantedradiotelemeters. O2 consumption rate was measured by using gas chromatography. In a previous study (S. R. Kayar and E. C. Parker. J. Appl.Physiol. 82: 988-997, 1997), we analyzed theO2 pulse, i.e., theO2 consumption rate per heartbeat, in the same animals. By multivariate regression analysis, weidentified variables that were significant toO2 pulse: body surface area,chamber temperature, core temperature, and pressure. In this study,inclusion of ATw made asignificantly better model with fewer variables. After normalizing forchamber temperature and pressure, theO2 pulse increased with increasing ATw in heliox(P = 0.001) but with decreasingATw in hydrox(P < 0.001). ThusATw is associated with thedifferences in O2 pulse foranimals breathing heliox vs. hydrox. 相似文献
83.
Nancy Argüelles Eugenia Sánchez-Sandoval Aarón Mendieta Lourdes Villa-Tanaca Leticia Garduño-Siciliano Fabiola Jiménez María del Carmen Cruz José L. Medina-Franco Germán Chamorro-Cevallos Joaquín Tamariz 《Bioorganic & medicinal chemistry》2010,18(12):4238-4248
A series of α-asarone-based analogues was designed by conducting docking experiments with published crystal structures of human HMG-CoA reductase. Indeed, synthesis and evaluation of this series showed a highly hypocholesterolemic in vivo activity in a murine model, as predicted by previous docking studies. In agreement with this model, the polar groups attached to the benzene ring could play a key role in the enzyme binding and probably also in its biological activity, mimicking the HMG-moiety of the natural substrate. The hypolipidemic action mechanism of these compounds was investigated by developing a simple, efficient, and novel model for determining HMG-CoA reductase inhibition. The partial purification of the enzyme from Schizosaccharomyces pombe allowed for testing of α-asarone- and fibrate-based analogues, resulting in positive and significant inhibitory activity. 相似文献
84.
85.
Maria Eugenia Teves Gobalakrishnan Sundaresan David J. Cohen Sharon L. Hyzy Illya Kajan Melissa Maczis Zhibing Zhang Richard M. Costanzo Jamal Zweit Zvi Schwartz Barbara D. Boyan Jerome F. Strauss III 《PloS one》2015,10(5)
Height is the result of many growth and development processes. Most of the genes associated with height are known to play a role in skeletal development. Single-nucleotide polymorphisms in the SPAG17 gene have been associated with human height. However, it is not clear how this gene influences linear growth. Here we show that a targeted mutation in Spag17 leads to skeletal malformations. Hind limb length in mutants was significantly shorter than in wild-type mice. Studies revealed differences in maturation of femur and tibia suggesting alterations in limb patterning. Morphometric studies showed increased bone formation evidenced by increased trabecular bone area and the ratio of bone area to total area, leading to reductions in the ratio of marrow area/total area in the femur. Micro-CTs and von Kossa staining demonstrated increased mineral in the femur. Moreover, osteocalcin and osterix were more highly expressed in mutant mice than in wild-type mice femurs. These data suggest that femur bone shortening may be due to premature ossification. On the other hand, tibias appear to be shorter due to a delay in cartilage and bone development. Morphometric studies showed reduction in growth plate and bone formation. These defects did not affect bone mineralization, although the volume of primary bone and levels of osteocalcin and osterix were higher. Other skeletal malformations were observed including fused sternebrae, reduced mineralization in the skull, medial and metacarpal phalanges. Primary cilia from chondrocytes, osteoblasts, and embryonic fibroblasts (MEFs) isolated from knockout mice were shorter and fewer cells had primary cilia in comparison to cells from wild-type mice. In addition, Spag17 knockdown in wild-type MEFs by Spag17 siRNA duplex reproduced the shorter primary cilia phenotype. Our findings disclosed unexpected functions for Spag17 in the regulation of skeletal growth and mineralization, perhaps because of its role in primary cilia of chondrocytes and osteoblasts. 相似文献
86.
87.
María Eugenia Caba?a-Mu?oz José María Parmigiani-Izquierdo Luis Alberto Bravo-González Hee-Moon Kyung José Joaquín Merino 《PloS one》2015,10(6)
Background
The induction of oxidative stress by Hg can affect antioxidant enzymes. However, epidemiological studies have failed to establish clear association between dental fillings presence and health problems.Objectives
To determine whether heavy metals (in hair), antioxidant enzymes (SOD-1) and glutathione levels could be affected by the chronic presence of heavy metals in women who had dental amalgam fillings.Materials and Methods
55 hair samples (42 females with amalgam fillings and 13 female control subjects) were obtained. All subjects (mean age 44 years) who had dental amalgam filling for more than 10 years (average 15 years). Certain metals were quantified by ICP-MS (Mass Spectrophotometry) in hair (μg/g: Al, Hg, Ba, Ag, Sb, As, Be, Bi, Cd, Pb, Pt, Tl, Th, U, Ni, Sn, Ti) and SOD-1 and Glutathione (reduced form) levels in plasma. Data were compared with controls without amalgams, and analyzed to identify any significant relation between metals and the total number of amalgam fillings, comparing those with four or less (n = 27) with those with more than four (n = 15). As no significant differences were detected, the two groups were pooled (Amlgam; n = 42).Findings
Hg, Ag, Al and Ba were higher in the amalgam group but without significant differences for most of the heavy metals analyzed. Increased SOD-1 activity and glutathione levels (reduced form) were observed in the amalgam group. Aluminum (Al) correlated with glutathione levels while Hg levels correlated with SOD-1. The observed Al/glutathione and Hg/SOD-1 correlation could be adaptive responses against the chronic presence of mercury.Conclusions
Hg, Ag, Al and Ba levels increased in women who had dental amalgam fillings for long periods. Al correlated with glutathione, and Hg with SOD-1. SOD-1 may be a possible biomarker for assessing chronic Hg toxicity. 相似文献88.
The K1 antigen is an important virulence determinant of Escherichia coli strains and has been shown to be associated particularly with neonatal meningitis, bacteraemia and septicaemia. Thus, its detection seems to be useful, especially in the case of E. coli strains isolated from pregnant women and newborns. In this study, the sensitivity and specificity of the latex agglutination test (Pastorex Meningitis) for identification of E. coli serogroup K1 were assessed, using PCR as the gold standard. Our results showed that consistency of results between latex agglutination test and PCR amounted to 98.5 %. Therefore, Pastorex Meningitis is a good alternative to PCR and could be used for rapid K1 antigen detection, especially in local non-specialized laboratories with limited resources where PCR assay is not applied. 相似文献
89.
90.
M. Eugenia Giorgi Laura Ratier Rosalía Agusti Alberto C. C. Frasch Rosa M. de Lederkremer 《Glycoconjugate journal》2010,27(5):549-559
Trypanosoma cruzi, the agent of Chagas disease, expresses a unique enzyme, the trans-sialidase (TcTS) involved in the transfer of sialic acid
from host glycoconjugates to mucins of the parasite. The enzyme is shed to the medium and may affect the immune system of
the host. We have previously described that lactose derivatives effectively inhibited the transfer of sialic acid to N-acetyllactosamine. Lactitol also prevented the apoptosis caused by the TcTS, although it is rapidly eliminated from the circulatory
system. In this paper we report covalent conjugation of polyethylene glycol (PEG) with lactose, lactobionolactone and benzyl
β-D-galactopyranosyl-(1→6)-2-amino-2-deoxy-α-D-glucopyranoside (1) with the hope to improve the bioavailability, though retaining their inhibitory properties. Different conjugation methods
have been used and the behavior of the PEGylated products in the TcTS reaction was studied. 相似文献