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Catherine Ronin Herman van Halbeek Johannah GM Mutsaers Johannes F G Vliegenthart 《Glycoconjugate journal》1987,4(3):247-254
The lipid-linked precursor ofN-type glycoprotein oligosaccharides was isolated from porcine thyroid microsomes after in cubation with UDP[3H] Glucose. The carbohydrate was released from dolichol pyrophosphate by mild acid hydrolysis, purified by gel filtration and characterized by 500-MHz1H-NMR spectroscopy in combination with enzymatic degradation. The parent oligosaccharide was found to be Glc3Man9Glc-NAc2. The three glucose residues are present in the linear sequence Glcα1-2Glα1-3 Glc, the latter being α(1-3)-linked to one of the mannose residues. In order to establish the branch location of the triglucosyl unit, the parent compound was digested with jack-bean α-mannosidase. The oligosaccharide product was purified by gel filtration, and identified by1H-NMR as Glc3Man5GlcNAc2 lacking the mannose residues A, D2, B and D3. Therefore, the structure of the precursor oligosaccharide is as follows: $$\begin{gathered} c b a D_1 C 4 \hfill \\ Glc\alpha 1 - 2Glc\alpha 1 - 3Glc\alpha 1 - 3Man\alpha 1 - 2Man\alpha 1 - 2Man\alpha 1 \hfill \\ 3 \swarrow 3 2 1 \hfill \\ Man\alpha 1 - 2Man\alpha 1 Man\beta 1 - 4GlcNAc\beta 1 - 4GlcNAc \hfill \\ D_{2 } A 3 6 \hfill \\ Man\alpha 1 \hfill \\ 6 \hfill \\ Man\alpha 1 - 2Man\alpha 1 \nwarrow 4 \hfill \\ D_3 B \hfill \\ \end{gathered} $$ 相似文献
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S. E. Ashmore A. S. Shapcott 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(2):249-259
Summary Investigations have been carried out on karyotype change in both callus and suspension cell cultures of Haplopappus gracilis (2n=4). It has been found that polyploidization arises directly in culture to give up to six times the normal diploid chromosome number in some cultures. In polyploid cultures, both chromosome loss and chromosome rearrangements occur to give rise to aneuploid karyotypes displaying chromosomes which differ in morphology from the diploid set. Whole or partial chromosome loss has been observed in the form of lagging chromosomes and chromosome bridges at anaphase, and micronuclei, ring chromosomes and chromosome fragments at other stages in mitosis. C-banded preparations have confirmed the occurrence of chromosomal rearrangements. Comparative investigations suggest that (i) more polyploidy occurs in callus cultures than in suspension cell cultures, and (ii) the presence of cytokinin (kinetin) in the culture medium may reduce the extent of karyotype change. 相似文献
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This study assessed the potential of two types of primate exhibit both for enhancing zoo visitors' interest, knowledge, and enjoyment and for promoting conservation education. Visitors' reactions to a free-ranging group of cotton-top tamarins were compared with their responses to caged tamarins in three ways: 1) timing how long visitors spent at each exhibit, 2) recording the comments made by visitors about the exhibits, and 3) asking visitors to respond to questionnaires about the two exhibits. The results showed that the free-ranging group of tamarins provoked wider comment from members of the public than caged groups and that visitors were willing to spend much more time looking for and watching monkeys in trees than monkeys in cages. Visitors felt that improvements in the animals' welfare were obtained from allowing them to live free in the trees, thought that they could learn more from such groups than from caged animals, and enjoyed seeing the free-ranging tamarins more than the monkeys in cages. These results suggest that developing more naturalistic zoo exhibits can have considerable benefits not only for the animals involved, but also for public education in conservation issues. © 1994 Wiley-Liss, Inc. 相似文献
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A. R. Gould S. E. Ashmore 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1982,64(1):7-12
Summary The polycation mediated attachment of purified tritiated DNA to plant protoplasts has been measured by quantitative microautoradiography. The automated grain counting technique used, also provides information on the cell cycle stage of individual protoplasts, which circumvents the need to synchronize the plant cell population before preparation of protoplasts. With protoplasts from asynchronously dividing suspension cultures of Nicotiana syhestris (NS-1), S-phase protoplasts appear to be inefficient binders of 3H-DNA, as compared with G1 or G2 protoplasts. Protoplasts derived from a tumour line of Crepis capillaris (CAPT) exhibit 3H-DNA binding at all cell cycle phases, but Sphase protoplasts appear to be preferential binders. These differences are discussed with reference to cell cycle kinetics, membrane charge variation and the possibility of increasing the efficiency of genetic transformation of higher plant cells in culture. 相似文献
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Summary Analysis of the cell cycle by three methods has revealed unusual kinetics of proliferation in tumour derived suspensions ofCrepis capillaris. The different methods of analysis yield different estimates of cycle phase durations, and such discrepancies have been explained in terms of low growth fractions with rapid total cycle traverse. Specifically, confidence in the estimation of G2 duration by the fraction of labelled mitosis analysis, and comparison with shorter G2 estimates obtained by the two other methods, suggests that cells drop out in G1. However, cells which do not drop out of the proliferative compartment traverse G1 extremely rapidly. Extremely short cell cycle durations in which the G1 phase is virtually non-existent are uncharacteristic of plant cell suspension cultures, in which the G1 phase has previously been shown to be extended as compared with meristematic root tip cells. A model has been proposed in which a central core of rapidly dividing cells continuously loses cells into a subpopulation of resting or G0 cells with the G1 DNA content. Similarities between plant and animal tumours with respect to cell growth and division are discussed. 相似文献