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Huijbregts RP Svitin A Stinnett MW Renfrow MB Chesnokov I 《Molecular biology of the cell》2009,20(1):270-281
The origin recognition complex or ORC is a six-subunit protein important for DNA replication and other cell functions. Orc6, the smallest subunit of ORC, is essential for both replication and cytokinesis in Drosophila, and interacts with the septin protein Pnut, which is part of the Drosophila septin complex. In this study, we describe the analysis of the interaction of Orc6 with Pnut and whole Drosophila septin complex. Septin complex was purified from Drosophila embryos and also reconstituted from recombinant proteins. The interaction of Orc6 with the septin complex is dependent on the coiled-coil domain of Pnut. Furthermore, the binding of Orc6 to Pnut increases the intrinsic GTPase activity of the Drosophila septin complex, whereas in the absence of GTP it enhances septin complex filament formation. These results suggest an active role for Orc6 in septin complex function. Orc6 might be a part of a control mechanism directing the cytokinesis machinery during the final steps of mitosis. 相似文献
23.
Most estrous cycles in cows consist of 2 or 3 waves of follicular activity. Waves of ovarian follicular development comprise
the growth of dominant follicles some of which become ovulatory and the others are anovulatory. Ovarian follicular activity
in cows during estrous cycle was studied with a special reference to follicular waves and the circulating concentrations of
estradiol and progesterone. Transrectal ultrasound examination was carried out during 14 interovulatory intervals in 7 cows.
Ovarian follicular activity was recorded together with assessment of serum estradiol and progesterone concentrations. Three-wave
versus two-wave interovulatory intervals was observed in 71.4% of cows. The 3-wave interovulatory intervals differed from
2-wave intervals in: 1) earlier emergence of the dominant follicles, 2) longer in length, and 3) shorter interval from emergence
to ovulation. There was a progressive increase in follicular size and estradiol production during growth phase of each wave.
A drop in estradiol concentration was observed during the static phase of dominant anovulatory follicles. The size of the
ovulatory follicle was always greater and produced higher estradiol compared with the anovulatory follicle. In conclusion,
there was a predominance of 3-wave follicular activity that was associated with an increase in length of interovulatory intervals.
A dominant anovulatory follicle during its static phase may initiate the emergence of a subsequent wave. Follicular size and
estradiol concentration may have an important role in controlling follicular development and in determining whether an estrous
cycle will have 2 or 3-waves. 相似文献
24.
Roots of representative epiphytic orchids were examined for anatomical detail, desiccation resistance and evidence of CAM activity. Those “shootless” taxa examined (Campylocentrum pachyrrhizum (Reichenb. f.) Rolfe, Harrisella porrecta Reichenb. f.) Fawc. & Rendle, and Polyradicion lindenii (Lindl.) Cogn. ex Urban) and a semi-shootless type (Kingidium taeniale (Lindl.) P. F. Hunt) bear thinner or eroded velamina and greater volumes of cortical intercellular space than do those of the leafy forms tested (Campylocentrum sellowii (Reichenb. f.) Rolfe, Encyclia tampensis (Lindl.) Small, Epidendrum radicans Pavon ex Lindl., Phalaenopsis amabilis (L.) Blume, Rangaeris amaniensis (Krzl.) Summerhayes and Vanda parishii (Reichenb. f.)). Shootless species also bear a more elaborate aeration apparatus at the velamen-cortex interface. Structurally distinct cortical cells located in this region may regulate gas exchange across the exodermis. Velamen thickness varies greatly among the ten species, as does the development of outer tangential walls of U cells in the underlying exodermis. Desiccation resistance under laboratory conditions was more closely related to root surface-to-volume ratio (S/V) than to any other measured anatomical parameter, including velamen development. Modes of carbon gain and the possible pathway for movement of fungus-borne carbon into an orchid's pool of assimilates are described, as is the possible significance of these processes to survival in forest canopy habitats. 相似文献
25.
The O-antigen chain from the lipopolysaccharide of Helicobacter pylori
strain UA861 was determined to be composed of an elongated type 2 N -
acetyllactosamine backbone,
-[-->3)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-(1- ]n-->, with
approximately half of the GlcNAc units carrying a terminal alpha-d-Glc
residue at the O -6 position. The O-chain of H.pylori UA861 was terminated
by a N -acetyllactosamine [beta-D-Gal-(1-->4)-beta-D- GlcNAc] (LacNAc)
epitope and did not express terminal Lewis X or Lewis Y blood-group
determinants as previously found in other H.pylori strains. The absence of
terminal Lewis X and Lewis Y blood-group epitopes and the replacement of
Fuc by Glc as a side chain in the O- chain of H.pylori UA861 represents yet
another type of lipopolysaccharide structure from H.pylori species. These
structural differences in H.pylori lipopolysaccharide molecules carry
implications with regard to possible different pathogenic events between
strains and respective hosts.
相似文献
26.
The first Australian record of the lily thrips, Liothrips vaneeckei Priesner, is reported from a bulb farm in Warragul South, Victoria. It is an occasional pest of Lilium bulbs, both in the field and in storage, particularly in the USA and several European countries, and is also infrequently found in considerable numbers on the corms of orchids. 相似文献
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Webber PJ Smith AD Sen S Renfrow MB Mobley JA West AB 《Journal of molecular biology》2011,412(1):94-110
The leucine-rich repeat kinase 2 (LRRK2) protein has both guanosine triphosphatase (GTPase) and kinase activities, and mutation in either enzymatic domain can cause late-onset Parkinson disease. Nucleotide binding in the GTPase domain may be required for kinase activity, and residues in the GTPase domain are potential sites for autophosphorylation, suggesting a complex mechanism of intrinsic regulation. To further define the effects of LRRK2 autophosphorylation, we applied a technique optimal for detection of protein phosphorylation, electron transfer dissociation, and identified autophosphorylation events exclusively nearby the nucleotide binding pocket in the GTPase domain. Parkinson-disease-linked mutations alter kinase activity but did not alter autophosphorylation site specificity or sites of phosphorylation in a robust in vitro substrate myelin basic protein. Amino acid substitutions in the GTPase domain have large effects on kinase activity, as insertion of the GTPase-associated R1441C pathogenic mutation together with the G2019S kinase domain mutation resulted in a multiplicative increase (∼ 7-fold) in activity. Removal of a conserved autophosphorylation site (T1503) by mutation to an alanine residue resulted in greatly decreased GTP-binding and kinase activities. While autophosphorylation likely serves to potentiate kinase activity, we find that oligomerization and loss of the active dimer species occur in an ATP- and autophosphorylation-independent manner. LRRK2 autophosphorylation sites are overall robustly protected from dephosphorylation in vitro, suggesting tight control over activity in vivo. We developed highly specific antibodies targeting pT1503 but failed to detect endogenous autophosphorylation in protein derived from transgenic mice and cell lines. LRRK2 activity in vivo is unlikely to be constitutive but rather refined to specific responses. 相似文献