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91.
Dietmar Helmut Pieper Karin Stadler-Fritzsche Karl-Heinrich Engesser Hans-Joachim Knackmuss 《Archives of microbiology》1993,160(3):169-178
2-Chloro-4-methylphenoxyacetate is not a growth substrate for Alcaligenes eutrophus JMP 134 and JMP 1341. It is, however, being transformed by enzymes of 2,4-dichlorophenoxyacetic acid metabolism to 2-chloro-4-methyl-cis, cis-muconate, which is converted by enzymatic 1,4-cycloisomerization to 4-carboxymethyl-2-chloro-4-methylmuconolactone as a dead end metabolite. Chemically, only 3,6-cycloisomerization occurs, giving rise to both diastereomers of 4-carboxychloromethyl-3-methylbut-2-en-4-olide. Those lactones harbonring a chlorosubstituent on the 4-carboxymethyl side chain were surprisingly stable under physiological as well as acidic conditions. 相似文献
92.
93.
Summary Intact armyworm moths (Spodoptera exempta, Farn. Noctuidae) were illuminated by polarized monochromatic light to induce structural changes in the rhabdomeres of the compound eyes. The degree of distortion of their microvilli depends on the light energy absorbed per time unit. Under polarized light, the number of quanta absorbed varies with the position of the plane of polarization relative to the axis of the microvilli (intrinsic dichroism). Therefore, in Spodoptera, different degrees of deformations could be demonstrated in differently oriented rhabdomeres of both types of ommatidia. Moreover, in rhabdoms of the lobed type with fan-like arranged microvilli, different reactions were regularly seen in differently oriented microvilli of one rhabdomere. This indicates that microvilli may react to light individually.Supported by Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 114 (Bionach) 相似文献
94.
Orth D Grif K Fisher I Fruth A Tschäpe H Scheutz F Dierich MP Würzner R 《Current microbiology》2006,53(5):428-429
Novel and as yet rare non-O157 Shiga toxin (Stx)-producing Escherichia coli (STEC) serotypes are emerging in Europe. Two different sorbitol-fermenting STECs, O100:H- carrying the virulence gene stx2 and O127:H40 carrying stx1 and eae genes (found in two related subjects), were isolated from patients’ stool samples. Non-O157 STEC infections in humans are
currently under-diagnosed. This report highlights the need for, and importance of, screening for Shiga toxins or serotypes
other than just O157. 相似文献
95.
96.
El Fitori J Kleeff J Giese NA Guweidhi A Bosserhoff AK Büchler MW Friess H 《Cancer cell international》2005,5(1):3
Background
Melanoma inhibitory activity (MIA) is a small secreted protein that interacts with extracellular matrix proteins. Its over-expression promotes the metastatic behavior of malignant melanoma, thus making it a potential prognostic marker in this disease. In the present study, the expression and functional role of MIA was analyzed in pancreatic cancer by quantitative real-time PCR (QRT-PCR), immunohistochemistry, immunoblot analysis and ELISA. To determine the effects of MIA on tumor cell growth and invasion, MTT cell growth assays and modified Boyden chamber invasion assays were used. 相似文献97.
Serial sections of 13 embryos and fetuses of the harbor porpoise from 10 mm crown-rump length up to 167 mm total length were studied. Unlike the adult animals, ontogenetic stages of 18–27 mm crown-rump length still show a typical mammalian olfactory bulb. The olfactory bulb primordium is penetrated by olfactory nerve fibers, the latter passing through the cribriform plate. However, the olfactory bulb anlage is gradually reduced in later stages, its placodal component being largely uncoupled from the telencephalon. As a ganglionlike structure, the remains of the placodal component stay in contact with the nasal septum and mucosa via thin bundles of nerve fibers. The ganglion and plexus can be traced within the meninges until the adult stage of the porpoise. There is strong evidence that they represent the material of the terminalis system, which cannot be distinguished from the olfactory system in earlier stages. A vomeronasal organ could not be detected in the embryonal and fetal material investigated. 相似文献
98.
The isomeric 4,4′-bi-2-phenyl-1,3,2-dioxaborolanes and 2,7-diphenyl-1,3,6,8-tetraoxa-2,7-diborabicyclo[4.4.0]decanes have been distinguished by their electron-impact induced fragmentation. The bisbenzeneboronates of erythritol, L-threitol, 1-deoxy-D-arabinitol, 1-deoxy-D-lyxitol, 1-deoxy-D-ribitol, 1-deoxy-D-xylitol, 1,6-dideoxygalactitol, and 1,6-dideoxy-L-mannitol are likely to be mixtures of structural isomers. 相似文献
99.
Eric M. Lind Elizabeth Borer Eric Seabloom Peter Adler Jonathan D. Bakker Dana M. Blumenthal Mick Crawley Kendi Davies Jennifer Firn Daniel S. Gruner W. Stanley Harpole Yann Hautier Helmut Hillebrand Johannes Knops Brett Melbourne Brent Mortensen Anita C. Risch Martin Schuetz Carly Stevens Peter D. Wragg 《Ecology letters》2013,16(4):513-521
Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade‐off possibilities. The competition‐defence hypothesis posits a trade‐off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth‐defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth‐defence trade‐off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life‐history groups and within the majority of individual sites. Thus, a growth‐defence trade‐off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint. 相似文献
100.
The effects of pressure, temperature and some organic solvents on the recovery of various lipid classes from plant and animal tissues can be assessed by fractional extraction with dense carbon dioxide and consecutive analysis by thin-layer chromatography. 相似文献