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31.
Ophioglossum petiolatum . Unlike Angiopteris (Marattiales), which is monoplastidic, Ophioglossum undergoes polyplastidic meiosis like members of the fern-seed plant clade. The meiotic spindle is distinctly multipolar in
origin and is consolidated into a bipolar spindle that is variously twisted and curved to accommodate the large number of
chromosomes. Although a phragmoplast forms after first meiosis, no wall is deposited. Instead, an organelle band consisting
of intermingled plastids and mitochondria is formed in the equatorial region between the dyad domains. Following second meiosis,
a complex of phragmoplasts forms among sister and non-sister nuclei. Cell plates are deposited first between sister nuclei
and then in the region of the organelle band resulting in a tetrad of spores each with a equal allotment of organelles.
Received 30 January 2001/ Accepted in revised form 24 April 2001 相似文献
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A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found. 相似文献
36.
K. T. Wieringa 《Antonie van Leeuwenhoek》1941,7(1):121-127
Conclusions In stable manure, leafmold and soils (especially those with a high content of organic material) agar decomposing bacilli are
relatively common. Different types of these organisms were isolated, the type described asBacillus agar-exedens being the one most frequently met. The occurrence of these bacteria in materials with a high content of organic matter suggests
the presence in these materials of higher organic compounds, especially apt for their nutrition. 相似文献
37.
K. T. Wieringa 《Plant and Soil》1963,18(1):53-69
Summary Changes in ion-exchange capacity and N-content of the organic matter occur when high-moor peat is composted at room temperature. The ion-exchange capacity increases, though slowly.Nitrogen is incorporated into the organic matter when the peat is composted with mineral fertilizers and N is applied as urea. The fixed nitrogen is not exchangeable with BaCl2 or Al2(SO4)3. It is assumed that micro-organisms play a part in this fixation.Nitrogen losses occur when, because of the nitrification process, the pH values drop below 5.5. 相似文献
38.
We here describe the identification and characterization of a novel bromodomain-containing protein, the bromodomain protein of 75 kDa (BP75). Initially, we identified BP75 in a two-hybrid screening for proteins that interact with the first PDZ (acronym for post-synaptic density protein PSD-95, Drosophila discs large tumor suppressor DlgA and the tight junction protein ZO-1) domain in protein tyrosine phosphatase-BAS-like (PTP-BL). We found that BP75 is expressed ubiquitously and show that both BP75 and a PTP-BL deletion mutant consisting of the first PDZ domain are located mainly in the nucleus, although cytoplasmic localization is also evident. Full-length PTP-BL, on the contrary, is predominantly localized in the cytoplasm, although some basal nuclear staining is observed. The described molecular interaction may reflect a mechanism of coupling submembraneous signalling events and nuclear events. 相似文献
39.
Chang EJ Ha J Oerlemans F Lee YJ Lee SW Ryu J Kim HJ Lee Y Kim HM Choi JY Kim JY Shin CS Pak YK Tanaka S Wieringa B Lee ZH Kim HH 《Nature medicine》2008,14(9):966-972
Osteoclasts differentiate from precursor cells of the monocyte-macrophage lineage and subsequently become activated to be competent for bone resorption through programs primarily governed by receptor activator of nuclear factor-kappaB ligand in cooperation with macrophage colony-stimulating factor. Proteins prominently expressed at late phases of osteoclastogenesis and with a supportive role in osteoclast function are potential therapeutic targets for bone-remodeling disorders. In this study, we used a proteomics approach to show that abundance of the brain-type cytoplasmic creatine kinase (Ckb) is greatly increased during osteoclastogenesis. Decreasing Ckb abundance by RNA interference or blocking its enzymatic activity with a pharmacological inhibitor, cyclocreatine, suppressed the bone-resorbing activity of osteoclasts grown in vitro via combined effects on actin ring formation, RhoA GTPase activity and vacuolar ATPase function. Activities of osteoclasts derived from Ckb-/- mice were similarly affected. In vivo studies showed that Ckb-/- mice were better protected against bone loss induced by ovariectomy, lipopolysaccharide challenge or interleukin-1 treatment than wild-type controls. Furthermore, administration of cyclocreatine or adenoviruses harboring Ckb small hairpin RNA attenuated bone loss in rat and mouse models. Our findings establish an important role for Ckb in the bone-resorbing function of osteoclasts and underscore its potential as a new molecular target for antiresorptive drug development. 相似文献
40.
Ralph J. A. Oude Ophuis Mietske Wijers Miranda B. Bennink Fons A. J. van de Loo Jack A. M. Fransen Bé Wieringa Derick G. Wansink 《PloS one》2009,4(11)