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51.
52.
The Electrophoretic Velocity of Human Red Cells, of Their Ghosts and Mechanically Produced Fragments, and of Certain Lipid Complexes 总被引:1,自引:0,他引:1 下载免费PDF全文
Ghosts prepared in CO2-saturated water from unwashed human red cells can be fragmented mechanically, but ghosts from thrice washed cells cannot. If the ghosts are prepared by freezing and thawing, this difference is not observed. The electrophoretic velocity varies also with the way in which the ghosts are prepared. The pH-mobility dependence of washed red cells flatten off to a plateau at pH 9, and the electrophoretic velocity is zero at about pH 2. Ghosts prepared by freezing and thawing have almost the same pH-mobility dependence, but if the ghosts are prepared in CO2-saturated hyptonic saline, the mobility at pH 9.4 is 0.75 times that of washed cells. Fragments of ghosts of unwashed red cells have a smaller mobility than that of the red cells. Trypsin reduces the mobility of washed red cells and of ghosts. Sols of lipid complexes (lecithin, cephalin, and lipositol), at varying pH's, have a mobility 1.2 times that of the washed red cell. The pH-mobility relation is otherwise similar. These complexes can be coated with dextran and trypsin. 相似文献
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R.Lucille Roberts Amy Zullo Eric A. Gustafson C.Sue Carter 《Hormones and behavior》1996,30(4):576-582
This experiment was designed to examine the hypothesis that perinatal manipulation of gonadal or adrenal steroids can alter the subsequent expression of juvenile parental (alloparenting) and affiliative behavior in prairie voles (Microtus ochrogaster). Corticosterone (PRECORT), testosterone (PRE-TP), or oil injections (PRESES) were given on Prenatal Days 12–20 or on Postnatal Days 1–6 (CORT6, TP6, or SES6, respectively). Alloparenting was reduced significantly in females in the CORT6 group and in males in the TP6 group. Sibling affiliative preferences were increased significantly in PRE-TP females and stranger preferences were increased in TP6 and CORT6 females. The results suggest timing is a critical factor determining whether hormones have a facilitative or inhibitory effect on alloparental and affiliative behavior in prairie voles. In this species, corticosterone and testosterone have similar organizational effects on affiliative behavior in females. Alloparental behavior is inhibited by postnatal corticosterone administration in females and by postnatal testosterone administration in males, whereas prenatal steroid administration had no significant effect on alloparenting in either gender. 相似文献
58.
The macrolide antibiotic, tylosin (Ty), is produced by Streptomyces fradiae. Two resistance determinants (tlrA, synonym ermSF, and tlrD) conferring resistance to macrolide, lincosamide and streptogramin B type (MLS) antibiotics were previously isolated from this strain, and their products shown to methylate 23S ribosomal RNA (rRNA) at a common site, thereby rendering the ribosomes MLS resistant. However, the T1rA and T1rD proteins differ in their action; the former dimethylates, and the latter monomethylates, the target nucleotide. Here, 2.2 kb of DNA from the tylLM region of the tylosin biosynthetic gene cluster of S. fradiae has been sequenced and shown to encompass tlrD. Comparison of the sequences of tlrA and tlrD (and of their deduced products) with those of related (‘erm-type’) genes from other actinomycetes suggests that the combined presence of tlrA and tlrD in S. fradiae is not the result of recent gene duplication. 相似文献
59.
Summary We report here an efficient Arabidopsis leafdisc transformation protocol yielding an average transformation frequency of 1.6 transgenic shoots per leaf explant 4 weeks after the bacterial infection period. Subsequent cultivation in vitro is such that a high percentage (85–90%) of the primary transformants produces seeds with an average seed yield of 100–300 seeds per plant. This improved transformation protocol yields mainly (70%) transformants segregating for a single T-DNA locus of which 68% actually contain one T-DNA insert. The objective is to generate a pool of independent transformants harboring an activator T-DNA construct in a gene tagging approach to isolate genes involved in morphogenesis and auxin signal transduction.Abbreviations
2,4-D
2,4-dichlorophenoxyacetic acid
-
AGM
Arabidopsis growth medium
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BAP
benzylaminopurine
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CaMV
Cauliflower Mosaic Virus
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CTAB
Hexadecyltrimethylammoniumbromide
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DIG
digoxigenin
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FeNaEDTA
Iron-sodium-ethylenedinitrilo tetraacetic acid complex
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GUS
ß-Glucuronidase
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IBA
indole-3-butyric acid
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LB
left T-DNA border
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MES
2-(N-morpholino) ethane sulfonic acid
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MS
Murashige and Skoog medium
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NAA
-naphthaleneacetic acid
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RB
right T-DNA border 相似文献
60.
Clayton E. Heyliger Talat J. Kheshgi Eric J. Murphy Sean Myers-Payne Friedhelm Schroeder 《Molecular and cellular biochemistry》1996,155(2):113-119
Relatively little is known of fatty acid specificity in cellular fatty acid uptake. In this study L-cells, a fibroblastic cell line with very low levels of endogenous cytosolic fatty acid binding protein, were used to examine the role of cis and trans unsaturation on fatty acid uptake. The fluorescent fatty acids, trans-parinaric acid and cis-parinaric acid, were used as analogs of straight-chain saturated, and kinked-chain unsaturated fatty acids, respectively, in order to evaluate the fatty acid specificity of the uptake system. Parinaric acid is poorly metabolizable; greater than 97% was unesterified while 3H-oleic acid was almost totally metabolized after 30 min uptake. Cis- and trans-parinaric acid uptake was saturable and dependent on the concentration of fatty acid. However, the initial rate and maximal amount of trans-parinaric acid taken up by the L-cells was greater than for cis-parinaric acid under the same conditions. The affinity of L-cell uptake for trans-parinaric acid (Km = 0.12 uM) was 35-fold higher than that for cis-parinaric acid (Km = 4.17 uM) . Based on competition studies with oleic and stearic acids, it was concluded that the cis- and trans-parinaric acid were taken up by the same L-cell fatty acid uptake system. The results suggest that the L-cell fatty acid uptake system has selectivity for straight chain rather than kinked chain unsaturated fatty acids.Abbreviations Cis-parinaric acid
9Z, 11E, 13E, 15Z-octatetraenoic acid
- trans-parinaric acid
9E, I IE, 13E, 15E-octatetraenoic acid
- EGTA
ethylene glycol-bis(beta-amlno-ethyl ether) N,N,N,N-tetratacetic acid
- BSA
bovine serum albumin
- PBS
phosphate buffered saline 相似文献