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1.
Gaelle Jan Violaine Delorme Nehm Saksouk Marie Abrivard Virginie Gonzalez Xavier Cayla Mohamed-Ali Hakimi Isabelle Tardieux 《Microbes and infection / Institut Pasteur》2009,11(12):935-945
Toxoplasma gondii is a human protozoan parasite that belongs to the phylum of Apicomplexa and causes toxoplasmosis. As the other members of this phylum, T. gondii obligatory multiplies within a host cell by a peculiar type of mitosis that leads to daughter cell assembly within a mother cell. Although parasite growth and virulence have been linked for years, few molecules controlling mitosis have been yet identified and they include a couple of kinases but not the counteracting phosphatases. Here, we report that in contrast to other animal cells, type 2C is by far the major type of serine threonine phosphatase activity both in extracellular and in intracellular dividing parasites. Using wild type and transgenic parasites, we characterized the 37 kDa TgPP2C molecule as an abundant cytoplasmic and nuclear enzyme with activity being under tight regulation. In addition, we showed that the increase in TgPP2C activity significantly affected parasite growth by impairing cytokinesis while nuclear division still occurred. This study supports for the first time that type 2C protein phosphatase is an important regulator of cell growth in T. gondii. 相似文献
2.
Roger Williams Herbert Axelrod Marie Greene Alexander McPherson 《Journal of Protein Chemistry》1987,6(4):343-352
The binding of pentaammineruthenium (III) to ribonuclease A and B both free and complexed with d(pA)4 has been examined in the crystalline state through the application of X-ray diffraction and difference Fourier techniques. In crystals of native RNase B, the reagent was observed to have many binding sites, some entirely electrostatic in nature and others consistent with coordination to histidine residues. The primary histidine in the latter case was 105 with 119 also partially substituted. In crystals of RNase A+d(pA)4 complex only a single, extremely strong site of substitution was observed, and this was 2.4 Å from the native position of the imidazole ring of histidine 105. Thus, the results of these X-ray diffraction studies appear to be quite consistent with the findings of earlier NMR studies and with the results obtained in crystals of the gene 5 DNA binding protein. 相似文献
3.
A Malassiné C Besse A Roche E Alsat R Rebourcet F Mondon L Cedard 《Histochemistry》1987,87(5):457-464
Low density lipoproteins (LDL) were conjugated to colloidal gold to visualize the route for internalization of LDL in the cultured cells of human term placenta. Cells were obtained from placental villi (caesarian section) by a standard trypsin-DNase dispersion method followed in some cases by a Percoll gradient centrifugation step. Employing electron microscopy it was observed that after 3 days of culture, cells obtained by trypsin-DNase dispersion were a mixture of macrophages, mononucleated cells and large multinucleated cells. When the cells were incubated for 3 days after the Percoll purification, essentially multinucleated cells identical to the syncytiotrophoblast were present. The number of LDL receptor was increased by preincubation in medium with lipoprotein depleted serum. In binding experiments cells incubated at 4 degrees C for 2 h with medium containing gold LDL conjugates showed gold LDL attached to the plasma membrane without characteristic localization. After incubation with gold LDL at 37 degrees C for various times, the three cellular types showed ligand internalization. Gold LDL endocytosis involved first coated pits but also uncoated plasmalemmal invaginations. Then gold LDL was further observed in coated and non coated vesicles, smooth walled endosomes, multivesicular bodies and tubular vesicles. Lastly free gold particles were observed in lysosome like dense bodies. These results prove the internalization of gold LDL conjugates by human cultured placental cells, particularly by syncytiotrophoblast like multinucleated cells. This accumulation of LDL (the major cholesterol carrying protein in humans) is recognised to be responsible for the exogenous cholesterol supply indispensable to the progesterone biosynthesis and cellular growth of the placenta. 相似文献
4.
5.
Marie Lipoldová Helena Havelková Jana Badalová Jarmila Vojtíšková Lei Quan Magdaléna Krulová Yahya Sohrabi Alphons P. Stassen Peter Demant 《Cancer immunology, immunotherapy : CII》2010,59(2):203-213
Low infiltration of lymphocytes into cancers is associated with poor prognosis, but the reasons why some patients exhibit
a low and others a high infiltration of tumors are unknown. Previously we mapped four loci (Lynf1–Lynf4) controlling lymphocyte infiltration of mouse lung tumors. These loci do not encode any of the molecules that are involved
in traffic of lymphocytes. Here we report a genetic relationship between these loci and the control of production of IFNγ
in allogeneic mixed lymphocyte cultures (MLC). We found that IFNγ production by lymphocytes of O20/A mice is lower than by
lymphocytes of OcB-9/Dem mice (both H2
pz
) stimulated in MLC by irradiated splenocytes of C57BL/10SnPh (H2
b
) or BALB/cHeA (H2
d
) mice, or by ConA. IFNγ production in MLCs of individual (O20 × OcB-9)F2 mice stimulated by irradiated C57BL/10 splenocytes and genotyped for microsatellite markers revealed four IFNγ-controlling
loci (Cypr4-Cypr7), each of which is closely linked with one of the four Lynf loci and with a cluster of susceptibility genes for different tumors. This suggests that inherited differences in certain
lymphocyte responses may modify their propensity to infiltrate tumors and their capacity to affect tumor growth. 相似文献
6.
7.
Neil E. Klepeis Suzanne C. Hughes Rufus D. Edwards Tracy Allen Michael Johnson Zohir Chowdhury Kirk R. Smith Marie Boman-Davis John Bellettiere Melbourne F. Hovell 《PloS one》2013,8(8)
Interventions are needed to protect the health of children who live with smokers. We pilot-tested a real-time intervention for promoting behavior change in homes that reduces second hand tobacco smoke (SHS) levels. The intervention uses a monitor and feedback system to provide immediate auditory and visual signals triggered at defined thresholds of fine particle concentration. Dynamic graphs of real-time particle levels are also shown on a computer screen. We experimentally evaluated the system, field-tested it in homes with smokers, and conducted focus groups to obtain general opinions. Laboratory tests of the monitor demonstrated SHS sensitivity, stability, precision equivalent to at least 1 µg/m3, and low noise. A linear relationship (R2 = 0.98) was observed between the monitor and average SHS mass concentrations up to 150 µg/m3. Focus groups and interviews with intervention participants showed in-home use to be acceptable and feasible. The intervention was evaluated in 3 homes with combined baseline and intervention periods lasting 9 to 15 full days. Two families modified their behavior by opening windows or doors, smoking outdoors, or smoking less. We observed evidence of lower SHS levels in these homes. The remaining household voiced reluctance to changing their smoking activity and did not exhibit lower SHS levels in main smoking areas or clear behavior change; however, family members expressed receptivity to smoking outdoors. This study established the feasibility of the real-time intervention, laying the groundwork for controlled trials with larger sample sizes. Visual and auditory cues may prompt family members to take immediate action to reduce SHS levels. Dynamic graphs of SHS levels may help families make decisions about specific mitigation approaches. 相似文献
8.
Chiara Pavanello Alice Ossoli Arianna Strazzella Patrizia Risè Fabrizio Veglia Marie Lhomme Paolo Parini Laura Calabresi 《Journal of lipid research》2022,63(7):100232
Mutations in the LCAT gene cause familial LCAT deficiency (Online Mendelian Inheritance in Man ID: #245900), a very rare metabolic disorder. LCAT is the only enzyme able to esterify cholesterol in plasma, whereas sterol O-acyltransferases 1 and 2 are the enzymes esterifying cellular cholesterol in cells. Despite the complete lack of LCAT activity, patients with familial LCAT deficiency exhibit circulating cholesteryl esters (CEs) in apoB-containing lipoproteins. To analyze the origin of these CEs, we investigated 24 carriers of LCAT deficiency in this observational study. We found that CE plasma levels were significantly reduced and highly variable among carriers of two mutant LCAT alleles (22.5 [4.0–37.8] mg/dl) and slightly reduced in heterozygotes (218 [153–234] mg/dl). FA distribution in CE (CEFA) was evaluated in whole plasma and VLDL in a subgroup of the enrolled subjects. We found enrichment of C16:0, C18:0, and C18:1 species and a depletion in C18:2 and C20:4 species in the plasma of carriers of two mutant LCAT alleles. No changes were observed in heterozygotes. Furthermore, plasma triglyceride-FA distribution was remarkably similar between carriers of LCAT deficiency and controls. CEFA distribution in VLDL essentially recapitulated that of plasma, being mainly enriched in C16:0 and C18:1, while depleted in C18:2 and C20:4. Finally, after fat loading, chylomicrons of carriers of two mutant LCAT alleles showed CEs containing mainly saturated FAs. This study of CEFA composition in a large cohort of carriers of LCAT deficiency shows that in the absence of LCAT-derived CEs, CEs present in apoB-containing lipoproteins are derived from hepatic and intestinal sterol O-acyltransferase 2. 相似文献
9.
F Monaco M Andreoli A La Posta J Roche 《Comparative biochemistry and physiology. B, Comparative biochemistry》1978,60(1):87-91
1. The biosynthesis of 18-19S thyroglobulin has been studied in a larval and adult freshwater lamprey (Lampetra planeri Bl.). 2. In vivo and in vitro experiments have been performed by injecting into the coelomic cavity or by incubating branchial region labeled constituents of Tg of higher vertebrates (125I, [3H]leucine and various [3H]carbohydrates). 3. Larvae (ammocoetes) and adults incorporate all labels into thyroglobulin (18-19S Tg), containing a small proportion of labeled T3 and T4, as identified by paper chromatography, and very minute amounts of stable iodine. 4. In adults, the biosynthesis of 18-19S Tg proceeds much more rapidly and the labels are incorporated in higher percentage than in larvae. 5. The demonstration of the biosynthesis of the specific thyroid protein, 18-19S Tg, in larvae indicates that the biochemical mechanism of hormonogenesis is present in larval endostyle before the morphological differentiation of thyroid cells and follicles occurring during metamorphosis. 6. Some 18-19S Tg is apparently stored in the endostyle. 相似文献
10.
E Roche E Knecht S Grisolía 《Biochemical and biophysical research communications》1987,142(3):680-687
2,3-bisphosphoglycerate at physiological concentration similar to that found in many tissues protects effectively ornithine transcarbamoylase (OTC) from proteolytic inactivation by broken lysosomes. 2,3-bisphosphoglycerate protects also many other mitochondrial and cytosolic proteins, such as glutamate dehydrogenase (GDH) an glyceraldehyde-3-phosphate dehydrogenase (GAPDH), from proteolysis by broken lysosomes and other proteases. It is, thus, suggested that 2,3-bisphosphoglycerate may play an important role in the control of the degradative rates of some proteins, which may explain its high concentration in certain cells. 相似文献