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11.
Angiopteris (Marattiales) undergoes the more primitive form of monoplastidic meiosis, while other ferns have evolved the polyplastidic
type typical of seed plants. In monoplastidic cell division, the single plastid divides and serves as site of the microtubule
organizing center (MTOC) for spindle formation resulting in coordinated division of plastid, nucleus, and cytoplasm. In plants
with polyplastidic cell division, the MTOC is diffuse and generally perinuclear. Monoplastidic cell division is seen as a
plesiomorphic feature that was inherited from algal ancestors containing a single plastid and modified through evolution.
Monoplastidic meiosis occurs in all groups of bryophytes (although in only a few hepatics), Isoetes, Selaginella, certain generic segregates of Lycopodium, and in members of the Marattiales. It is not known to occur in psilophytes, Equisetum, leptosporangiate ferns, or seed plants.
Received 30 January 2001/ Accepted in revised form 24 April 2001 相似文献
12.
An inhibitor of chick kidney mitochondrial 25-hydroxyvitamin D3-1-hydroxylase has been isolated from rat serum by ammonium sulfate precipitation, gel filtration, ionexchange chromatography, and preparative polyacrylamide disc gel electrophoresis. The purified protein was shown to contain iron and has a mol wt of 52 000. The protein is indistinguishable on gel electrophoresis from a similar inhibitor found in rat kidney tissue. The physiological significance of the inhibitor is not known; however, it seems possible that it is responsible for the failure to demonstrate in vitro 25-hydroxyvitamin D3-l-hydroxylation with rat and other mammalian tissues. 相似文献
13.
Expression and activity of osteoblast-targeted Cre recombinase transgenes in murine skeletal tissues
Liu F Woitge HW Braut A Kronenberg MS Lichtler AC Mina M Kream BE 《The International journal of developmental biology》2004,48(7):645-653
The Cre/loxP recombination system can be used to circumvent many of the limitations of generalized gene ablation in mice. Here we present the development and characterization of transgenic mice in which Cre recombinase has been targeted to cells of the osteoblast lineage with 2.3 kb (Col 2.3-Cre) and 3.6 kb (Col 3.6-Cre) fragments of the rat Col1a1 promoter. Cre mRNA was detected in calvaria and long bone of adult Col 2.3-Cre and Col 3.6-Cre mice, as well as in tendon and skin of Col 3.6-Cre mice. To obtain a historical marking of the temporal and spatial pattern of Cre-mediated gene rearrangement, Col-Cre mice were bred with ROSA26 (R26R) mice in which Cre-mediated excision of a floxed cassette results in LacZ expression. In Col 2.3-Cre;R26R and Col 3.6-Cre;R26R progeny, calvarial and long bone osteoblasts showed intense beta-gal staining at embryonic day 18 and postnatal day 5. The spatial pattern of beta-gal staining was more restricted in bone and in bone marrow stromal cultures established from Col 2.3-Cre;R26R mice. Similar differences in the spatial patterns of expression were seen in transgenic bone carrying Col1a1-GFP visual reporters. Our data suggest that Col 2.3-Cre and Col 3.6-Cre transgenic mice may be useful for conditional gene targeting in vivo or for obtaining osteoblast populations for in vitro culture in which a gene of interest has been inactivated. 相似文献
14.
15.
G. B. Stefano N. Pilonis R. Ptacek J. Raboch M. Vnukova R. M. Kream 《Cellular and molecular neurobiology》2018,38(6):1197-1206
It has become apparent that the molecular and biochemical integrity of interactive families, genera, and species of human gut microflora is critically linked to maintaining complex metabolic and behavioral processes mediated by peripheral organ systems and central nervous system neuronal groupings. Relatively recent studies have established intrinsic ratios of enterotypes contained within the human microbiome across demographic subpopulations and have empirically linked significant alterations in the expression of bacterial enterotypes with the initiation and persistence of several major metabolic and psychiatric disorders. Accordingly, the goal of our review is to highlight potential thematic/functional linkages of pathophysiological alterations in gut microbiota and bidirectional gut–brain signaling pathways with special emphasis on the potential roles of gut dysbiosis on the pathophysiology of psychiatric illnesses. We provide critical discussion of putative thematic linkages of Parkinson’s disease (PD) data sets to similar pathophysiological events as potential causative factors in the development and persistence of diverse psychiatric illnesses. Finally, we include a concise review of preclinical paradigms that involve immunologically–induced GI deficits and dysbiosis of maternal microflora that are functionally linked to impaired neurodevelopmental processes leading to affective behavioral syndromes in the offspring. 相似文献
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Prostaglandin synthesis by fetal rat bones was examined by thin-layer chromatography of culture media after preincubation with labeled arachidonic acid. Cultures in rabbit complement (non-heat inactivated serum) were compared with cultures in heat-inactivated serum or cultures treated with indomethacin. The major complement-dependent products were PGE2, PGF2 alpha and 6-keto-PGF1 alpha, the metabolite of prostacyclin (PGI2). Since PGI2 had not been previously identified in bone its ability to stimulate bone resorption was tested. Repeated addition of PGI2 stimulated release of previously incorporated 45Ca from fetal rat long bones in both short-term and long-term cultures at concentrations of 10(-5) to 10(-9)M. Because of the short half life of PGI2 in solution at neutral pH, we tested a sulfur analog, thiaprostacyclin (S-PGI2) which was found to be a stimulator of bone resorption at concentrations of 10(-5) to 10(-6)M. These studies suggest that endogenous PGI2 production may play a role in bone metabolism. Since vessels produce PGI2 it is possible that PGI2 release may be responsible for the frequent association between vascular invasion and resorption of bone or calcified cartilage in physiologic remodeling and pathologic osteolysis. 相似文献
18.
Differential utilization of regulatory domains within the alpha 1(I) collagen promoter in osseous and fibroblastic cells 总被引:5,自引:0,他引:5 下载免费PDF全文
19.
NM Kouyoumdzian NL Rukavina Mikusic G Cao MR Choi SL Della Penna BE Fernández 《Biotechnic & histochemistry》2016,91(8):510-521
We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis. 相似文献
20.
Jacob G. Ghazarian Barbara Kream Kathleen M. Botham Michael W. Nickells Hector F. DeLuca 《Archives of biochemistry and biophysics》1978,189(1):212-220
An antibody was prepared from serum of rabbits injected with a pure inhibitor protein obtained from rat serum for chick renal 25-hydroxyvitamin D3-1α-hydroxylase. The antibody was separated from the endogenous inhibitor in rabbit serum. The antibody shows a single precipitin line with the rat serum antigen and with crude calf serum. Furthermore, the antibody removes the 4.0 S 25-hydroxyvitamin D3 binding protein from rat serum. The removal of the 25-hydroxyvitamin D3 binding protein from rat serum with antibody brings about a proportionate removal of inhibitor of the 25-hydroxyvitamin D3-1α-hydroxylase. The pure inhibitor binds 25-hydroxyvitamin D3, as demonstrated by sucrose density gradient sedimentation, and shows specificity of binding identical to the serum transport globulin for 25-hydroxyvitamin D3. Thus, the previously reported inhibitor of the 25-hydroxyvitamin D3-1α-hydroxylase in rat preparations is the serum 25-hydroxyvitamin D3 transport protein or some derivative thereof. The antibody added to rat renal mitochondrial preparations does increase the activity of the 1- and 24-hydroxylases slightly but not markedly. 相似文献