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991.
Evgeniia Prokhorova Thomas Agnew Anne R. Wondisford Michael Tellier Nicole Kaminski Danique Beijer James Holder Josephine Groslambert Marcin J. Suskiewicz Kang Zhu Julia M. Reber Sarah C. Krassnig Luca Palazzo Shona Murphy Michael L. Nielsen Aswin Mangerich Dragana Ahel Jonathan Baets Ivan Ahel 《Molecular cell》2021,81(12):2640-2655.e8
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992.
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994.
Montembault E Zhang W Przewloka MR Archambault V Sevin EW Laue ED Glover DM D'Avino PP 《The Journal of cell biology》2010,191(7):1351-1365
Cytokinesis, the final step of cell division, usually ends with the abscission of the two daughter cells. In some tissues, however, daughter cells never completely separate and remain interconnected by intercellular bridges or ring canals. In this paper, we report the identification and analysis of a novel ring canal component, Nessun Dorma (Nesd), isolated as an evolutionarily conserved partner of the centralspindlin complex, a key regulator of cytokinesis. Nesd contains a pectin lyase-like domain found in proteins that bind to polysaccharides, and we present evidence that it has high affinity for β-galactosides in vitro. Moreover, nesd is an essential gene in Drosophila melanogaster, in which it is required for completion of cytokinesis during male meiosis and possibly in female germline cells. Our findings indicate that Nesd is a novel carbohydrate-binding protein that functions together with centralspindlin in late cytokinesis, thus highlighting the importance of glycosylation in this process. 相似文献
995.
Two classes of RNase H hydrolyze RNA of RNA/DNA hybrids. In contrast to RNase H1 that requires four ribonucleotides for cleavage, RNase H2 can nick duplex DNAs containing a single ribonucleotide, suggesting different in vivo substrates. We report here the crystal structures of a type 2 RNase H in complex with substrates containing a (5')RNA-DNA(3') junction. They revealed a unique mechanism of recognition and substrate-assisted cleavage. A conserved tyrosine residue distorts the nucleic acid at the junction, allowing the substrate to function in catalysis by participating in coordination of the active site metal ion. The biochemical and structural properties of RNase H2 explain the preference of the enzyme for junction substrates and establish the structural and mechanistic differences with RNase H1. Junction recognition is important for the removal of RNA embedded in DNA and may play an important role in DNA replication and repair. 相似文献
996.
Lewandowska H Brzóska K Meczyńska-Wielgosz S Rumianek K Wójciuk G Kruszewski M 《Postepy biochemii》2010,56(3):298-304
Formation of dinitrosyl iron complexes (DNICs), which can be described by general formula Fe(NO)2(L)2, where L is carbonyl-, nitrosyl- or imino- complexing ligand, was observed in many kinds of living organisms, in a wide spectrum of physiological conditions associated with inflammation, ischemia/reperfusion and cancer. Accumulation of DNICs coincides with intensified production of nitric oxide in macrophages, neurons, endothelial cells, Langerhans' cells and hepatocytes. Low-molecular thiol-containing DNICs (DNIC-(RS)2) show vasodilatory action and they are proposed to play a role of nitric oxide transducers and stabilizers. DNICs have been shown to modulate redox potential of the cell via inhibition of glutathione-dependent enzymes, such as glutathione reductase, S-transferase and peroxidase. Although there is a convincing experimental evidence for their NO and NO+ donating function, the nature of DNICs formed in biological systems, their stability and biological role is still a matter of discussion. 相似文献
997.
Słuczanowska-Głąbowska S Laszczyńska M Wylot M Głąbowski W Piasecka M Gącarzewicz D 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2010,48(3):447-454
The prolactin plays an important role in the regulation of growth and differentiation of prostate gland besides androgens. The goal of this study was to reveal the influence of elevated prolactin concentration on epithelial cells of prostate. We compared the morphology of epithelial cells of prostate dorsal, lateral and ventral lobes and expression of androgen receptors in these cells in rats with hyperprolactinemia and in control rats. We used sexually mature male Wistar rats. The experimental rats received metoclopramide; the control group received saline in the same way. The prostate dorsal, lateral and ventral lobes were collected routinely for light and electron microscopy. The intensity of immunohistochemical reaction of androgen receptor in epithelial cells of dorsal, lateral and ventral lobes was evaluated by measure of optical density with computer image analysis. The light and electron (transmission and scanning) microscopes were used for morphological observations. Results: In experimental rats twofold increase in prolactin and twofold decrease in testosterone found. In experimental group the expression of androgen receptor was lower in columnar epithelial cells of dorsal and ventral lobes but higher in lateral one. We observed morphological abnormalities in columnar epithelial cells of lateral and dorsal lobes. The columnar epithelial cells of ventral lobes didn't show any morphological changes in hyperprolactinemia. 相似文献
998.
Abstract. The ultrastructure of the male reproductive system in the polyclad flatworm Pleioplana atomata is described. Numerous testes are scattered throughout the entire body but are heavily concentrated on the ventral side. All stages of differentiating sperm cells are present in all testes follicles. Intercellular bridges connect spermatocytes and spermatids derived from a single spermatogonium. In the distal part of spermatids, a zone of differentiation develops with a row of microtubules beneath the plasmalemma. Adjacent to these microtubules, an intercentriolar body is flanked by two basal bodies that give rise to two axonemes (each with a 9+“1” microtubular pattern) that face in opposite directions. The Golgi complex appears in the central portion of the spermatid and produces numerous small and large electron-dense bodies. The small bodies surround the nucleus, whereas the large bodies cluster along with the mitochondria in the central part of the spermatid. Development of the spermatid leads to cell elongation and formation of a filiform, biflagellate mature spermatozoon with cortical microtubules all along the sperm shaft. The male canal system consists of paired vasa deferentia that separately enter a single seminal vesicle. A single prostatic canal connects the seminal vesicle to the prostatic vesicle. Ultrastructurally, the seminal vesicle and prostatic canal are very similar, and along with the prostatic vesicle and stylet pocket, are lined by a ciliated epithelium. The ultrastructure of the prostatic vesicle indicates that it probably produces a large volume of seminal fluid that, along with spermatozoa, is transferred to the mating partner through a stylet. Some of the findings, particularly on sperm ultrastructure, may provide characters useful for phylogenetic analysis. 相似文献
999.
Atmospheric nitrogen deposition is associated with elevated phosphorus limitation of lake zooplankton 总被引:1,自引:0,他引:1
James J. Elser Angela L. Peace Marcia Kyle Marcin Wojewodzic Michelle L. McCrackin Tom Andersen Dag O. Hessen 《Ecology letters》2010,13(10):1256-1261
Here, we present data that for the first time suggests that the effects of atmospheric nitrogen (N) deposition on nutrient limitation extend into the food web. We used a novel and sensitive assay for an enzyme that is over‐expressed in animals growing under dietary phosphorus (P) deficiency (alkaline phosphatase activity, APA) to assess the nutritional status of major crustacean zooplankton taxa in lakes across a gradient of atmospheric N deposition in Norway. Lakes receiving high N deposition had suspended organic matter (seston) with significantly elevated carbon:P and N:P ratios, indicative of amplified phytoplankton P limitation. This P limitation appeared to be transferred up the food chain, as the cosmopolitan seston‐feeding zooplankton taxa Daphnia and Holopedium had significantly increased APA. These results indicate that N deposition can impair the efficiency of trophic interactions by accentuating stoichiometric food quality constraints in lake food webs. 相似文献
1000.
Agnieszka Noszczyk-Nowak Marcin Nowak Urszula Paslawska Wojciech Atamaniuk Jozef Nicpon 《Acta veterinaria Scandinavica》2010,52(1):35
In the period of 3 years, 9 tumours of chemodectoma were supravitally diagnosed and histopathologically verified in dogs. In this period 15 351 dogs were admitted to the Clinic
of Dogs and Cats and 2 145 dogs were examined in the cardiological outpatient clinic for dogs. This tumour is located in a
typical place - at the base of the heart. Most frequently the tumour manifested in older boxers. Only in one case such a tumour
was diagnosed in another breed of dogs. The tumours ranged in size between 3 and 16 cm in diameter. The principal sign accompanying
tumours of cardiac base involved dyspnoea but in 3 cases the tumours yielded no clinical signs. All the diagnoses were additionally
verified using immunohistochemical examination. We used antibodies to chromogranin A (clone DAK-A3 1:100), synaptophysin (clone
SY38 1:20) and neuron-specific enolase (clone BBS/NC/VI-H14 1:150). An immunohistochemical examination is vital for the diagnosis
since it allows to differentiate histologically distinct types of neoplasia which may locate in the same site and may manifest
a similar histological pattern. 相似文献