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531.
Methyl 1α, 3α-dihydroxy 5β-cholan-24-oate was synthesized to provide a model compound for the mass spectrometric identification of 1α-hydroxylated bile acids. 相似文献
532.
533.
The isolation is reported of tifruticin, acetyltifruticin, deoxytifruticin, acetyldeoxytifruticin, an orizabin analog and three heliangolides from Helianthus maximiliani. 相似文献
534.
Werner Herz Inger Wahlberg Charles S. Stevens Palaiyur S. Kalyanaraman 《Phytochemistry》1975,14(8):1803-1808
Examination of Liatris chapmanii (T + G) Kuntze led to the isolation of two new germacranolides, chapliatrin (1a) and isochapliatrin (1b). Liatris gracilis Pursh gave chapliatrin and acetylchapliatrin 1c). The stereochemistry assigned to C-3, C-4 and C-10 is tentative. All three compounds possess the hitherto-unreported 5,10-oxygen linkage. L. gracilis also gave the benzofuran euparin (2) and the flavones hispidulin (dinatin, 3a and 3′,6-dimethoxy-4′,5,7-trihydroxyflavone (3b). L. chapimanii also gave 5-hydroxy-3′,4′,6,7-tetramethoxyflavone (3c). 相似文献
535.
Easier detection of invertebrate "identification-key characters" with light of different wavelengths
Evolutionary arms-races between avian brood parasites and their hosts have typically resulted in some spectacular adaptations, namely remarkable host ability to recognize and reject alien eggs and, in turn, sophisticated parasite egg mimicry. In a striking contrast to hosts sometimes rejecting even highly mimetic eggs, the same species typically fail to discriminate against highly dissimilar parasite chicks. Understanding of this enigma is still hampered by the rarity of empirical tests - and consequently evidence - for chick discrimination. Recent work on Australian host-parasite systems (Gerygone hosts vs. Chalcites parasites), increased not only the diversity of hosts showing chick discrimination, but also discovered an entirely novel host behavioural adaptation. The hosts do not desert parasite chicks (as in all previously reported empirical work) but physically remove living parasites from their nests. Here, I briefly discuss these exciting findings and put them in the context of recent empirical and theoretical work on parasite chick discrimination. Finally, I review factors responsible for a relatively slow progress in this research area and suggest most promising avenues for future research. 相似文献
536.
Jaruwan Kampa Karl Ståhl Lena HM Renström Stefan Alenius 《Acta veterinaria Scandinavica》2007,49(1):7
Background
Bovine viral diarrhoea virus (BVDV) is an important pathogen in cattle. The ability of the virus to cross the placenta during early pregnancy can result in the birth of persistently infected (PI) calves. These calves shed the virus during their entire lifespan and are the key transmitters of infection. Consequently, identification (and subsequent removal) of PI animals is necessary to rapidly clear infected herds from the virus. The objective of this study was to evaluate the suitability of a commercial Erns-capture ELISA, in comparison to the indirect immunoperoxidase test (IPX), for routine diagnostic detection of BVDV within a control programme. In addition, the effect of passive immunity and heat-inactivation of the samples on the performance of the ELISA was studied. 相似文献537.
G. Schwarz M. Herz X. Q. Huang W. Michalek A. Jahoor G. Wenzel V. Mohler 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(3-4):545-551
Genetic mapping and the selection of closely linked molecular markers for important agronomic traits require efficient, large-scale
genotyping methods. A semi-automated multifluorophore technique was applied for genotyping AFLP marker loci in barley and
wheat. In comparison to conventional 33P-based AFLP analysis the technique showed a higher resolution of amplicons, thus increasing the number of distinguishable
fragments. Automated sizing of the same fragment in different lanes or different gels showed high conformity, allowing subsequent
unambigous allele-typing. Simultaneous electrophoresis of different AFLP samples in one lane (multimixing), as well as simultaneous
amplification of AFLP fragments with different primer combinations in one reaction (multiplexing), displayed consistent results
with respect to fragment number, polymorphic peaks and correct size-calling. The accuracy of semi-automated co-dominant analysis
for hemizygous AFLP markers in an F2 population was too low, proposing the use of dominant allele-typing defaults. Nevertheless, the efficiency of genetic mapping,
especially of complex plant genomes, will be accelerated by combining the presented genotyping procedures.
Received: 10 April 1999 / Accepted: 11 May 1999 相似文献
538.
539.
We have recently isolated from bovine adrenal medulla a novel C-terminally amidated opioid peptide, amidorphin, which derives from proenkephalin A. Amidorphin revealed a widespread distribution in bovine, ovine, and porcine tissue. Particularly high concentrations of amidorphin immunoreactivity were detected in adrenal medulla, posterior pituitary, and striatum, similar to the major gene products of proenkephalin A. In the adrenal medulla of each species, authentic amidorphin was the predominant immunoreactive form. Pituitary and brain, however, contained predominantly putative N-terminally shortened fragments of amidorphin of a slightly lower molecular weight and shorter retention times on HPLC. In addition, in ovine adrenal medulla, a putative high-molecular-weight form of amidorphin was detected. These findings are indicative of a tissue-specific processing of the proenkephalin A precursor, leading predominantly to authentic amidorphin in the adrenal medulla and further processing to smaller C-terminal fragments in the brain and pituitary. 相似文献
540.