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Joseph Gyekis David A. Blizard Joseph T. Stout David J. Vandenbergh Gerald E. McClearn Reinmar Hager 《Evolutionary biology》2011,38(4):434-440
Trade-offs occur when two traits have opposing fitness effects such that positive selection on one trait is constrained by
the negative fitness consequences of the other trait. To understand why trade-off may arise we need to study the genetic and
non-genetic factors that influence associated traits because these may respond differently to selective pressure. Research
into trade-offs has largely focused on the genetic basis of associated traits, yet both maternal effects and epigenetic effects
have recently been shown to affect life history traits that play a role in trade-offs. In this study, we analyze genetic,
epigenetic and life-history predictors of one of the most important trade-offs, that between offspring number and offspring
mortality. Using a large-scale 3-generational intercross between two divergent mouse lines C57BL/6J and DBA/2J, we show that
litter size differences between these lines, although significant, are surprisingly not the most important predictors of mortality.
Offspring genotype, maternal effects and their interactions are the most influential factors determining mortality. We found
significant paternal effects suggesting an important influence of paternal care or potentially the role of imprinted genes.
Perhaps contrary to expectations our results further show that the trade-off between offspring number and mortality is not
just a simple function of the two factors yielding, on average, an ‘optimal’ litter size at weaning. Indeed if one focused
on litter size and mortality alone, the slope of relationship is the same for the two lines, yet they differ in the number
of young at weaning. Our study reveals that a perceived trade-off between two traits is governed by a more complex set of
interactions between genetic and non-genetic effects. 相似文献
587.
Biodegradation of ethylene glycol was tested in a laboratory-scale, steady-state infiltration system of two arid region soil
types by monitoring indigenous microbial growth after the infiltration of three concentrations of ethylene glycol. Microorganisms
in the soils were able to adapt to the ethylene glycol in several cases, resulting in higher numbers of microorganisms and
lower pHs in the effluents. These microorganisms were identified and were able to use ethylene glycol as a sole carbon source.
The adaptation was seen best with high-moisture-content soils when the ethylene glycol concentrations were 1% or 10%. However,
acclimation to 0.1% and 10% ethylene glycol did not occur in low-moisture-content clay soil, but did occur in low-moisture-content
silt soil, indicating that soil type and moisture content are important factors. In all cases, microbial diversity decreased
over time.
Received: 23 June 1997 / Accepted: 11 August 1997 相似文献
588.
Fluorometric quantitation of single-stranded DNA: a method applicable to the technique of alkaline elution 总被引:6,自引:0,他引:6
The use of Hoechst dye 33258 for the fluorometric quantitation of single-stranded DNA was investigated for the purpose of developing a simple nonradiometric method of quantitating DNA in fractions collected during the analysis of DNA damage by the method of alkaline elution. The sensitivity of the assay allowed amounts of single-stranded DNA as small as 100 ng to be quantitated reliably. The requirement of a near-neutral pH necessitated that alkaline samples be buffered in order to perform DNA quantitation. However, that the addition of a predetermined volume of buffered dye solution to each sample is the only manipulation required prior to fluorescence measurement makes this procedure the simplest yet described for quantitating DNA collected during alkaline elution. 相似文献
589.
A. Howard Fieldsteel James G. Stout Frances A. Becker 《In vitro cellular & developmental biology. Plant》1981,17(1):28-32
Summary During attempts to cultivateTreponema pallidum, it was determined that length of time for survival of virulent treponemes was highly dependent on the quality of the fetal
bovine serum (FBS) used as a protein supplement in the culture medium. Eighteen lots of commercial FBS were tested for their
ability to maintain survival ofT. pallidum in cultures of cottontail rabbit epithelial (SflEp) cells. All were capable of supporting growth of these cells. However,
in tests on five of the lots, attachment of treponemes to the SflEp cells was either extremely poor or the 50% survival time
(ST50) was less than 5 days. With two of these lots, no treponemes survived for 5 days. By contrast, in tests with 11 of the FBS
lots, the ST50 of the treponemes was 12 days or greater; however, there was a great variation in the number of treponemes that attached.
Selection of lots of FBS for ultimate experimental use was based on their influence both to extend length of time for survival
of treponemes and to increase the number of treponemes that attached to the SflEp cells during that period. 相似文献
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