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1.
Sandra Danner Christiane Kirchhoff Richard Ivell 《Reproductive biology and endocrinology : RB&E》2009,7(1):67-14
Background
Post-meiotically expressed genes in the testis are essential for the proper progression of spermatogenesis, and yet, aside from the construction of individual transgenic mice using specific promoters to drive reporter plasmids, there are only very limited possibilities for relevant and quantitative analysis of gene promoters. This is due to the special nature of post-meiotic haploid cells, which to date are not represented in any appropriate cell-lines. This article reports the development of novel methodology using isolated and cultured rat seminiferous tubules in a multiwell format, into which promoter-reporter constructs can be introduced by a combination of microinjection and electroporation. 相似文献2.
The ultrastructure and distribution of receptor cells near the mouth and (where present) the pharynx of Hofstenia miamia, Proporus bermudensis, Conaperta thela, and Convoluta convoluta (Acoela) were investigated by transmission electron microscopy and confocal laser scanning microscopy of specimens stained with a fluorescence marker for actin. Five types of monociliary receptors were identified: (1) non‐collared receptors with a single long and narrow ciliary rootlet; (2) non‐collared receptors with a wide main ciliary rootlet and a smaller posterior rootlet; (3) non‐collared receptors with a single wide and hollow ciliary rootlet with a granulated core; (4) Collar (?) receptors with obliquely radial filament bundles in the cell apex and with a single hollow ciliary rootlet composed of numerous strand‐like elements; and (5) Collar receptors lacking a striated rootlet but with a granular body (swallow's nest rootlet). While H. miamia bears the first two receptor types, P. bermudensis has receptors of type 1, 3 and 5, and Cona. thela and Conv. convoluta have receptors of type 3, 4 and 5. The density of receptors is generally highest at the anterior body tip, regardless of where the mouth is located. Most receptor types occur scattered over the whole body but type 2 receptors of H. miamia are restricted to the pharynx and mouth region. The lack of a common receptor type specific for the mouth and pharynx of the investigated species points to an independent origin of the pharynges in Hofsteniidae and in Proporidae and of the mouth tube in Convolutidae. Moreover, the homology of the so‐called collar receptors in Acoela with typical collar receptors in other invertebrates is questioned. 相似文献
3.
When following the pattern of the disappearance of NH
4
+
–N from ammonium sulfate applied to the flooded soil-rice plant system (field and greenhouse experiments) during a growing season, it was observed that the lowest NH
4
+
–N level coincided with the highest value of NR activity in the leaves. Nitrate was detected in both the root and shoot systems of the rice plants and autotrophic nitrifiers (Nitrosomonas and Nitrobacter) were particularly abundant. Since it was also demonstrated in this work that the NR activity of rice plants grown with nitrate fertilization (growth chamber culture experiments) was inducible by its substrate, it can be assumed that NH
4
+
–N oxidation takes place in the water-logged soil studied. Therefore, the occurrence of the nitrification process following NH
4
+
–N fertilizer application can be predicted by thein vitro orin situ evaluation of the NR activity of the rice leaf as an indicator. 相似文献
4.
Genetic convergence during serial in vitro passage of a polyclonal squamous cell carcinoma 总被引:1,自引:0,他引:1
A cell line was established from an in situ squamous cell carcinoma of the skin (Bowen's disease), and its in vitro karyotypic evolution was cytogenetically analyzed. Initially, considerable genetic heterogeneity was evident. Nine cytogenetically abnormal clones, eight of which were apparently unrelated, were found among the 83 metaphases analyzed from the primary culture and the first passage. With increasing time in culture this complexity was reduced, so that a single clone dominated passages 7-11. The clone that emerged from this genetic convergence had a t(12;17)(p13;q21) as the sole abnormality. Our findings indicate that the cytogenetic multiclonality that has been repeatedly detected in short-term cultures of squamous cell carcinomas is not caused by the in vitro conditions. Instead, the principles of Darwinian selection apply: the altered, but stable, selection pressure facing a newly established and initially multiclonal cell line will lead to a reduction of genetic heterogeneity until the one clone that now has the proliferative advantage outgrows the other subpopulations. 相似文献
5.
Christiane Wloczyk Achim Kröger Thomas Göbel Gabriele Holdt Ralf Steudel 《Archives of microbiology》1989,152(6):600-605
Wolinella succinogenes grown on formate and elemental sulphur was found to use the polysulphide derivatives 2,2-tetrathiobispropionate (R2S4) or pentathionate (S5O
6
=
) as acceptors for formate oxidation. The specific activities of formate oxidation with these acceptors were similar to those with elemental sulphur. The main reaction products of R2S4 reduction were 2,2-dithiobispropionate (R2S2) and sulphide. Pentathionate was converted to thiosulphate and some elemental sulphur. The electrochemical proton potential
across the cytoplasmic membrane of the bacterium was measured in the steady state of electron transport from formate to R2S4. The electrical proportion () of the
determined through the distribution of labeled tetraphenylphosphonium cation was obtained as 0.17 Volt. The was zero, when a protonophore was present. The pH-difference across the membrane was negligible. Thus the
generated by sulphur respiration is close to that measured earlier with fumarate as the terminal acceptor of electron transport.Abbreviations DMO
5,5-dimethyloxazolidine-2,4-dione
- R2Sn (n=2–5)
2,2-polythiobispropionate
- TTFB
4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazol
- TPP
tetraphenylphosphonium cation 相似文献
6.
Mef Nilbert Sverre Heim Nils Mandahl Ulla-Maria Flodérus Helena Willén Felix Mitelman 《Human genetics》1990,85(6):605-611
Summary The cytogenetic analysis of 224 leiomyomas from 138 patients is presented. An insufficient number of mitoses was found in 35 tumors, normal karyotypes in 145, and clonal chromosome aberrations were detected in 44. The three previously identified cytogenetic subgroups were all represented in this series: del(7) (q21.2q31.2) was found in 11, trisomy 12 in five, and t(12;14)(q14-15;q23-24) in one leiomyoma. Rearrangements of 6p, including deletions, inversions, and various translocations, were found in eight tumors, thus delineating a new cytogenetic subgroup of uterine leiomyoma. The remaining 21 karyotypically abnormal tumors had nonrecurrent changes. One leiomyoma had two cytogenetically unrelated clones characterized by del(7)(q21.2 q31.2) and +12. Karyotypic changes in two separate leiomyomas from the same uterus were identified in five patients; in three of them, different anomalies were found in the two tumors, whereas cytogenetically identical aberrations – del(7q) and dic(21;22) – were detected in two macroscopically discrete tumors. These findings suggest that whereas some multiple leiomyomas originate independently, others may be derived from the same neoplastic clone. 相似文献
7.
Christiane Levrat Dominique Ardail Renée Morelis Pierre Louisot 《Glycoconjugate journal》1988,5(4):449-466
The results reported in this paper show two distinct ways for the incorporation ofN-acetylglucosamine into mitochondrial outer membranes. The first one is the glycosylation of dolichol acceptors, which is indicated by the inhibition of the synthesis of these products by the inhibitors of the dolichol intermediates (tunicamycin and GDP). The second one is the incorporation ofN-acetylglucosamine into protein acceptors directly from UDP-N-acetylglucosamine. This second way of glycosylation is only localized in mitochondria outer membranes.The existence of a direct route forN-glycoprotein biosynthesis has been based on the following evidence. First, the synthesis of theN-acetylglucosaminylated protein acceptors was not inhibited by tunicamycin or GDP. Second, the addition of exogenous dolichol-phosphate did not change the rate of biosynthesis of glycosylated protein material. Third, the sequential incorporation ofN-acetylglucosamine and mannose from their nucleotide derivatives in the presence of GDP and tunicamycin led to the synthesis of glycosylated protein material which entirely bound to Concanavalin A-Sepharose. The oligosaccharide moiety of the glycosylated protein material resulting from the direct transfer of sugars from their nucleotide derivatives to the protein acceptor is of theN-glycan type. On sodium dodecylsulphate polyacrylamide gel electrophoresis, this glycosylated material migrated as a marker protein with a molecular weight between 45 000 and 63 000. HPLC chromatofocusing analysis revealed that the fraction studied was anionic. The oligosaccharide moiety of the glycoprotein material can only be elongated by the incorporation ofN-acetylglucosamine and galactose from their nucleotide derivatives. 相似文献
8.
Prevalence of the 281 (Gly→Glu) mutation in hepatoerythropoietic porphyria and porphyria cutanea tarda 总被引:4,自引:0,他引:4
Hubert de Verneuil Joanna Hansen Christiane Picat Bernard Grandchamp James Kushner Andrew Roberts George Elder Yves Nordmann 《Human genetics》1988,78(1):101-102
Summary The prevalence of the 281 (GlyGlu) mutation in hepatoerythropoietic porphyria (HEP) was investigated by the use of hybridization with a synthetic oligonucleotide probe. The mutation was found in HEP-affected members of two unrelated families from Spain, but was absent in two other patients from Italy and Portugal who also had HEP. Moreover, this mutation was not detected in 13 unrelated cases of familial (type II) porphyria cutanea tarda. 相似文献
9.
Cell cultures ofThalictrum
rugosum released their protoberberine alkaloids into the medium, when cells were transferred to fresh medium lacking phosphate. The nutritional factors required and the impact of the cells' physiological state for the alkaloid excretion were analyzed. Cell cultures, having released their alkaloids into the medium, continued to grow when the alkaloid containing medium was replaced by fresh growth medium. 相似文献
10.