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801.
802.
803.
Nan E. Watson Bernard A. Prior James C. du Preez Pieter M. Lategan 《Enzyme and microbial technology》1984,6(10):447-450
The oxygen requirements for ethanol production from d-xylose (10 or 20 g l?1) by Pachysolen tannophilus have been determined by controlling the availability of oxygen to shake flasks. Under anaerobic conditions no ethanol was produced whereas under aerobic conditions mainly biomass was formed. Semi-anaerobic conditions resulted in maximum ethanol production. By varying the stirring speed of a fermenter and supplying air to the liquid surface at various rates, the oxygen transfer rate (OTR) was controlled under semi-anaerobic conditions. By increasing the OTR from 0.05 to 16.04 mmol l?1 h?1, the ethanol yield coefficient decreased from 0.28 to 0.18 while the cell yield coefficient increased from 0.14 to 0.22. The accumulation of polyols decreased from 0.88 to 0.56 g l?1 with increasing OTR. At OTRs between 0.09 and 1.18 mmol l?1 h?1, specific ethanol productivity attained a maximum value of 0.07 h?1 and decreased with either increasing or decreasing OTR. The results indicate that the OTR must be carefully controlled for efficient ethanol production from d-xylose by P. tannophilus. 相似文献
804.
Summary Balance studies on bottom deposits to which standard synthetic detergent (manoxol) was added and which were incubated for three days revealed that biochemical degradation of the detergent takes place to a considerable extent. Maximum degradation as assessed by difference between added and recovered manoxol after incubation takes place in samples of pronounced biochemical activity (dehydrogenase activity), while in samples which exhibit high adsorption characteristics the degradation of manoxol is impaired. In active sediments an increase in the residual adsorbed manoxol was observed in sediments which showed a relatively high adsorption capacity for manoxol. Negligible degradation was found after incubation in sediments lacking biochemical activity. 相似文献
805.
Michel Giollant Suzanne Bertrand Pierre Verrelle Stanislas du Manoir Thomas Ried Françoise Mornex Jean-François Doré Thomas Cremer P. Malet A Tchirkov 《Human genetics》1996,98(3):265-270
The presence of double minute chromosomes (dmin) in cancer cells is known to be correlated with gene amplifications. In human
high grade astrocytomas or glioblastomas, about 50% of cytogenetically characterized cases display dmin. G5 is a cell line
which has been established from a human glioblastoma containing multiple dmin. In order to identify the DNA content of these
dmin, three techniques were successively used: conventional cytogenetic analysis, comparative genomic hybridization (CGH),
and fluorescent in situ hybridization (FISH). The karyotype of G5 cells showed numerical chromosome changes (hypertriploidy),
several marker chromosomes, and multiple dmin. CGH experiments detected two strong DNA amplification areas located in 9p21-22
and 9p24, as well as an underrepresentation of chromosomes 6, 10, 11, 13, 14, and 18q. By using FISH with a chromosome 9-specific
painting probe to metaphase chromosomes of the G5 cell line, dmin were shown to contain DNA sequences originating from chromosome
9. This study demonstrates the usefulness of a combination of classical karyotyping, CGH, and FISH to identify the chromosomal
origin of amplified DNA sequences in dmin.
Received: 30 October 1994 / Revised: 25 February 1996 相似文献
806.
807.
Olivier Berry Enora Briand Alizé Bagot Maud Chaigné Laurence Meslet-Cladière Julien Wang Olivier Grovel Jeroen J. Jansen Nicolas Ruiz Thibaut Robiou du Pont Yves François Pouchus Philipp Hess Samuel Bertrand 《Environmental microbiology》2023,25(2):250-267
The comprehension of microbial interactions is one of the key challenges in marine microbial ecology. This study focused on exploring chemical interactions between the toxic dinoflagellate Prorocentrum lima and a filamentous fungal species, Aspergillus pseudoglaucus, which has been isolated from the microalgal culture. Such interspecies interactions are expected to occur even though they were rarely studied. Here, a co-culture system was designed in a dedicated microscale marine-like condition. This system allowed to explore microalgal–fungal physical and metabolic interactions in presence and absence of the bacterial consortium. Microscopic observation showed an unusual physical contact between the fungal mycelium and dinoflagellate cells. To delineate specialized metabolome alterations during microalgal–fungal co-culture metabolomes were monitored by high-performance liquid chromatography coupled to high-resolution mass spectrometry. In-depth multivariate statistical analysis using dedicated approaches highlighted (1) the metabolic alterations associated with microalgal–fungal co-culture, and (2) the impact of associated bacteria in microalgal metabolome response to fungal interaction. Unfortunately, only a very low number of highlighted features were fully characterized. However, an up-regulation of the dinoflagellate toxins okadaic acid and dinophysistoxin 1 was observed during co-culture in supernatants. Such results highlight the importance to consider microalgal–fungal interactions in the study of parameters regulating toxin production. 相似文献
808.
Gert J. Steyn Christo L. Gagiano Andrew R. Deacon Hein H. du Preez 《Environmental Biology of Fishes》1996,47(4):387-398
Synopsis In South Africa, the distributional range of tigerfish,Hydrocynus vittatus, has diminished over the past fifty years mainly as a result of migration barriers and reduced river flow. A project to restock traditional tigerfish waters has been envisaged for many years but did not materialise due to an inability to spawn this species artificially. Several hormones were therefore tested for their potency to induce ovulation in this species. Gonadotropin releasing hormones (GnRh) were used in combination with dopamine receptor antagonists. Human chorionic gonadotropin (HCG) was administered in conjunction with catfish pituitary gonadotropin. Both sexes were successfully stripped and the eggs were inseminated artificially. Tigerfish eggs are small (0.65 mm diameter), demersal and slightly adhesive. Hatching occurs 22 h 30 min after insemination and free embryos are pelagic and display continuous vertical movement for a period of three days. Embryonic development was photographed until first feeding, 5 days after hatching. From these results as well as field observations, it is concluded that tigerfish spawns on a sandy substrate in the vicinity of aquatic vegetation. 相似文献
809.
Summary Samples of bottom deposits were taken from a total of twenty-six stations in five areas along the Vaal River and analysed
for dehydrogenase activity, organic carbon, Kjeldahl nitrogen, inorganic carbon, humic acids, degree of humification, cationic
adsorption capacity and exchangeable bases. BOD determinations on the flowing water were also done at these stations.
The relation between the characteristics of the sediments and the presence or absence of pollution was examined.
It was concluded that analysis of the sediments can provide a valuable index of the state of pollution of natural waters. 相似文献