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High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans 总被引:1,自引:0,他引:1
We compared male-reproductive-tract polypeptides of Drosophila melanogaster
and D. simulans by using two-dimensional gel electrophoresis. Approximately
64% of male-reproductive-tract polypeptides were identical between two
randomly chosen isofemale lines from these two species, compared with 83%
identity for third-instar imaginal wing-disc polypeptides. Qualitatively
similar differences were found between reproductive tracts and imaginal
discs when D. sechellia was compared with D. melanogaster and with D.
simulans. When genic polymorphism was taken into account, approximately 10%
of male- reproductive-tract polypeptides were apparently fixed for
different alleles between D. melanogaster and D. simulans; this proportion
is the same as that found for soluble enzymes by one-dimensional gel
electrophoresis. Strikingly, approximately 20% of male-reproductive- tract
polypeptides of either D. melanogaster or D. simulans had no detectable
homologue in the other species. We propose that proteins of the Drosophila
male reproductive tract may have diverged more extensively between species
than have other types of proteins and that much of this divergence may
involve large changes in levels of polypeptide expression.
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Exponentially growing cultures ofNitrosomonas europaea were inhibited by addition of 0.5 g nitrapyrin ml–1. This inhibition was increased by simultaneous addition of 0.046 g Cu2+ ml–1 as copper sulfate. This contradicts a previous report that copper relieves inhibition of ammonia oxidation by nitrapyrin, which report has formed the basis for hypotheses regarding the mechanism of action of this inhibitor. 相似文献
5.
The d. c. conductivity of five samples of NaDNA in dry state was investigated. All specimens show similar behavior, with specific resistivity at 40°C of the order of 1013–1014 ohm-cm and an energy gap of Ec = 2.04–2.25 eV. Based on the Eley's model for conductivity mechanism, the possibility of conservation of an ordered structure in the dry state (temperature range 20–80°C) is discussed. This is ascribed to the interaction of electron systems of individual bases. From the activation energy values it may be estimated that 17–19 π-electrons take part in the interaction. Photoconductivity measurements indicated activation energies Ef of 0.88–0.96 eV in the visible region. 相似文献
6.
Luminescence-based nonextractive technique for in situ detection of Escherichia coli in soil 总被引:2,自引:0,他引:2
E A Rattray J I Prosser K Killham L A Glover 《Applied and environmental microbiology》1990,56(11):3368-3374
Measurement of light output by luminometry was used to estimate quantitatively the cell concentrations of luminescent strains of Escherichia coli in liquid culture and inoculated into soil. Strains were constructed in which luciferase production was autoinducible or constitutive. In the former, light output per cell varied considerably during growth but was constant in constitutive strains. In liquid culture, the lower detection limit was in the order of 10(2) cells ml-1. Sensitivity was reduced by approximately 1 order of magnitude for cells inoculated into soil, when 2 x 10(2) to 6 x 10(3) cells g of soil-1 could be detected. Light output measurements were obtained within 5 min of sampling, and luminometry therefore potentially offers a rapid and sensitive detection technique for genetically engineered microorganisms. 相似文献
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Human satellite I sequences include a male specific 2.47 kb tandemly repeated unit containing one Alu family member per repeat 总被引:6,自引:1,他引:5
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A portion of human satellite I DNA is digested by HinfI into three fragments of 775, 875 and 820bp in length which form a tandemly repeated unit 2.47kb in length, specific to male DNA. One Alu family member per repeat is found within the relatively G+C rich 775bp fragment. The 875 and 820bp fragments are highly A+T rich and consist of long stretches of poly dAdT and related sequences. 相似文献
10.
RS Fisher 《The Journal of general physiology》1977,69(5):571-604
When the outer surface of short-circuited frog skin was penetrated with microelectrodes, stable negative potentials that averaged near -100 mV were recorded consistently, confirming the results of Nagel (W. Nagel. 1975. Abstracts of the 5th International Biophysics Congress, Copenhagen. P-147.). The appearance of these stable potentials, V(O), concurrent with the observations that (a) a high resistance outer barrier R(O) accounting for approximately 75 percent or more of the transcellular resistance of control skins had been penetrated and that (b) 10(-5) M amiloride and reduced [Na] outside caused the values of V(O) to increase towards means value near -130 mV while the values of percent R(O) increased to more than 90 percent. It was of relationships were the same as the values of E(1) observed in studies of the current-voltage relationships were the same as the values of E’(1) defined as the values of voltage at the inner barrier when the V(O) of the outer barrier was reduced to zero by voltage clamping of the skins. Accordingly, these data are interpreted to mean that the values of E(1), approximately 130 mV, represent the E(Na) of the sodium pump at the inner barrier. 2,4-DNP was observed to decrease the values of transepithelial voltage less than E(1) the V(O) was negative. These data can be interpreted with a simple electrical equivalent circuit of the active sodium transport pathway of the frog skin that includes the idea that the outer membrane behaves as an electrical rectifier for ion transport. 相似文献