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581.
Summary Degradation of asparagine in media containing dialyzed fetal calf serum has been shown to be the result of asparaginase, which
is active even at 4°C. The asparaginase activity of undialyzed fetal calf serum is only one-tenth of that found in the dialyzed
serum. Glutaminase activity was also demonstrated in the medium containing dialyzed fetal calf serum. Minor changes in some
other amino acids were also observed.
This work was supported in part by Grant CA02568, National Cancer Institute, National Institutes of Health. 相似文献
582.
A Müller J Hermann D Fuchs J Prager E Burger D Kob I Goetz F Zintl 《Folia haematologica (Leipzig, Germany : 1928)》1989,116(3-4):475-479
The elimination of erythrocytes by dextran sedimentation is a useful method to prevent haemolytic complications after AB0-incompatible bone marrow transplantation. The procedure presented here lasts only 1.5-2 hours, is high reproducible and safe in respect of infections. The mean recovery of nucleated cells amounted to 94%. The contamination with erythrocytes is low (recovery 1.1%). We have never seen haemolytic reactions during 7 AB0-incompatible bone marrow transplantations. 相似文献
583.
584.
Diaphragmatic O2 and lactate extraction were examined in seven healthy ponies during maximal exercise (ME) carried out without, as well as with, inspiratory resistive breathing. Arterial and diaphragmatic venous blood were sampled simultaneously at rest and at 30-s intervals during the 4 min of ME. Experiments were carried out before and after left laryngeal hemiplegia (LH) was produced. During ME, normal ponies exhibited hypocapnia, hemoconcentration, and a decrease in arterial PO2 (PaO2) with insignificant change in O2 saturation. In LH ponies, PaO2 and O2 saturation decreased well below that in normal ponies, but because of higher hemoglobin concentration, arterial O2 content exceeded that in normal ponies. Because of their high PaCO2 during ME, acidosis was more pronounced in LH animals despite similar lactate values. Diaphragmatic venous PO2 and O2 saturation decreased with ME to 15.5 +/- 0.9 Torr and 18 +/- 0.5%, respectively, at 120 s of exercise in normal ponies. In LH ponies, corresponding values were significantly less: 12.4 +/- 1.3 Torr and 15.5 +/- 0.7% at 120 s and 9.8 +/- 1.4 Torr and 14.3 +/- 0.6% at 240 s of ME. Mean phrenic O2 extraction plateaued at 81 and 83% in normal and LH animals, respectively. Significant differences in lactate concentration between arterial and phrenic-venous blood were not observed during ME. It is concluded that PO2 and O2 saturation in the phrenic-venous blood of normal ponies do not reach their lowest possible values even during ME. Also, the healthy equine diaphragm, even with the added stress of inspiratory resistive breathing, did not engage in net lactate production. 相似文献
585.
Vitamin B12 and the macromolecular composition of Euglena. I. Kinetic analysis of the cell cycle and chloroplast replication 总被引:1,自引:0,他引:1
A R Christopher K Dobrosielski-Vergona G Goetz P L Johnston E F Carell 《Experimental cell research》1974,89(1):71-78
The kinetics of cell division, chloroplast replication and mean DNA/cell of cultures progressing through B12 deficiency do not follow smooth curves, but contain transient plateaus which are consistent mathematically with the hypothesis that one portion of the Euglena cell cycle, the S phase, is differentially extended under B12 deficiency. A computer simulation of the B12-deficient cultures was capable of duplicating the division kinetics of the actual culture. Chloroplast replication in B12-deficient cells is not directly affected by B12 deficiency, but is a function of the division kinetics of the cells. The chloroplasts continue to replicate initially at a high rate after the cells have entered B12 deficiency, and then follow the kinetics of the cells. 相似文献
586.
587.
We examined annual variation in the timing of conception andparturition in the African buffalo (Syncerus caffer) and thesynchrony of birth timing with resource cues, using 8 yearsof monthly birth, rainfall, and vegetation data, measured asNormalized Difference Vegetation Index (NDVI). Monthly birthshad the strongest significant correlations with NDVI and rainfalllevels 12 and 13 months in the past, respectively. In addition,the synchrony of current year births corresponds most stronglyto the synchrony of the previous year's NDVI distribution. Becausethe gestation period of buffalo has been estimated to be around11 months, these findings suggest that improved protein levels,occurring approximately a month after the first green flushof the wet season, are either a trigger for conception or conceptionhas evolved to be synchronous with correlated environmentalcues that ensure females enter a period of peak body conditionaround the time of conception and/or parturition. With a gestationperiod of approximately 340 days, parturition occurs to takeadvantage of the period when forage has its highest proteincontent. A comparative analysis of gestation periods withinthe subfamily Bovinae indicates that African buffalo have aprotracted gestation for their body size, which we suggest isan adaptation to their seasonal environment. We also found thatinterannual variation in the birth distribution suggests a degreeof plasticity in the date of conception, and variation in thenumber of calves born each year suggest further synchrony ata timescale longer than a single year. 相似文献
588.
589.
Goetz Hensel Vladimir Valkov Jill Middlefell-Williams Jochen Kumlehn 《Journal of plant physiology》2008,165(1):71
Stable genetic transformation represents the gold standard approach to the detailed elucidation of plant gene functions. This is particularly relevant in barley, an important experimental model widely employed in applied molecular, genetic and cell biological research, and biotechnology. Presented are details of the establishment of a protocol for Agrobacterium-mediated gene transfer to immature embryos, which enables the highly efficient generation of transgenic barley. Advancements were achieved through comparative experiments on the influence of various explant treatments and co-cultivation conditions. The analysis of representative numbers of transgenic lines revealed that the obtained T-DNA copy numbers are typically low, the generative transmission of the recombinant DNA is in accordance with the Mendelian rules and the vast majority of the primary transgenics produce progeny that expresses the respective transgene product. Moreover, the newly established protocol turned out to be useful to transform not only the highly amenable cultivar (cv.) ‘Golden Promise’ but also other spring and winter barley genotypes, albeit with substantially lower efficiency. As a major result of this study, a very useful tool is now available for future functional gene analyses as well as genetic engineering approaches. With the aim to modify the expression of barley genes putatively involved in plant–fungus interactions, numerous transgenic plants have been generated using diverse expression cassettes. These plants represent an example of how transformation technology may contribute to further our understanding of important biological processes. 相似文献
590.
Ingeburg E. Goetz Randi Moklebust Catherine J. Warren 《In vitro cellular & developmental biology. Plant》1979,15(2):114-119
Summary During serial subcultures 50 μg per ml gentamicin and penicillin (100 U per ml)-streptomycin (100 μg per ml) depressed cell
growth significantly 2 weeks after the addition of the antibiotics; gentamicin, but not penicillin-streptomycin, stimulated
cell growth before it became inhibitory. Removal of the antibiotics resulted in the cell yield returning to normal. The results
show that these antibiotics can be harmful to cells even at concentrations thought to be safe. 相似文献