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101.
P Mamont A Hershko R Kram L Schacter J Lust G M Tomkins 《Biochemical and biophysical research communications》1972,48(6):1378-1384
The reactions included in the definition of this regulatory program, called the “pleiotypic response”, are very similar to those under “stringent” control in bacteria. The latter appears to be mediated by a novel nucleotide, ppGpp, and we therefore assayed for the presence of this nucleotide in cultured fibroblasts under a variety of conditions of growth restriction which elicit the pleiotypic response. We were unable to detect it in any of these circumstances and we conclude that ppGpp is not the mediator of the pleiotypic response, at least in the cell lines studied. 相似文献
102.
Free and membrane-bound ribosomes in rat liver 总被引:17,自引:0,他引:17
103.
104.
Jeffrey W. Adelberg Maria P. Delgado Jeffery T. Tomkins 《In vitro cellular & developmental biology. Plant》2010,46(1):95-107
Residual nutrients from Murashige and Skoog medium were analyzed following a 5-wk multifactor experiment. Plant density, sugar
concentration, and plant growth regulators (benzyladenine and ancymidol) were examined using four genotypes of daylily (Hemerocallis) to determine which factors most influenced nutrient use. Active nutrient uptake was observed for 11 nutrients (potassium,
sodium, copper, phosphorus, iron, calcium, magnesium, manganese, boron, sulfur, and zinc) with lower concentrations in spent
medium than in the tissue water volume (fresh-dry mass expressed as mL H2O). Two patterns of nutrient use were visualized by correlative analysis of nutrient uptake. Greatest growth lowered plant
nutrient concentrations of potassium, sodium, phosphorus, iron, and copper in all genotypes, and luxuriant uptake was indicated
with least growth. Potassium, sodium, iron, and copper concentrations in plant dry matter were equal to or exceeded what is
observed in vigorously growing nursery plants. However, phosphorus concentration in plant dry matter was low enough to be
considered deficient when compared to Hemerocallis plants in nursery production. With a second group of nutrients (calcium, magnesium, manganese, and boron), the genotype,
“Barbara Mitchell” lacked active uptake and was deficient. Calcium concentration was low in all plants compared to Hemerocallis grown under nursery conditions (“Barbara Mitchell” was the lowest concentration) despite active uptake by the other three
genotypes—“Brocaded Gown,” “Mary’s Gold,” and “Heart of a Missionary.” Magnesium concentration in these three genotypes was
low enough in vessels with greatest growth to question its adequacy at high densities. Increased sucrose in medium reduced
the dry matter concentrations of all tested nutrients. Plant growth regulators had less impact on nutrient use than genotype
and plant density. Nutrient uptake may be an important physiological component of genotypic variation. 相似文献
105.
Lukasik P Radwan J Tomkins JL 《Evolution; international journal of organic evolution》2006,60(2):399-403
Alternative reproductive tactics in males are often associated with divergent phenotypes expressed as phenotypically plastic threshold traits. The evolution of threshold traits in these species has been modeled under the conditional evolutionarily stable strategy (ESS). Both strategic and genetic models predict that perturbations to the fitness trade-off between the male morphs will lead to a shift in the ESS switch point of the threshold. So far, demographic factors that influence the competitive ability of male morphs have been investigated and related to intraspecific population variation in male dimorphic thresholds. Here we reveal evidence for the theoretical prediction that abiotic features of the environment, in particular its structural complexity, are likely to influence the ESS threshold. In the male dimorphic mite Sancassania berlesei, we monitored the survival of aggressive fighter males and their benign scrambler counterparts in populations that differed in structural complexity. We found that, consistent with our prediction, the complex habitat favored fighter males, enabling them to kill a greater number of rival scramblers. We found no effect of habitat complexity on the survival of fighter males. These results demonstrate how abiotic as well as biotic aspects of the environment can be important in determining the frequencies of males adopting alternative tactics in different species or populations. 相似文献
106.
Cunningham C Hikima J Jenny MJ Chapman RW Fang GC Saski C Lundqvist ML Wing RA Cupit PM Gross PS Warr GW Tomkins JP 《Marine biotechnology (New York, N.Y.)》2006,8(5):521-533
Large-insert genomic bacterial artificial chromosome (BAC) libraries of two culturally and economically important oyster species,
Crassostrea virginica and C. gigas, have been developed as part of an international effort to develop tools and reagents that will advance our ability to conduct
genetic and genomic research. A total of 73,728 C. gigas clones with an average insert size of 152 kb were picked and arrayed representing an 11.8-fold genome coverage. A total of
55,296 clones with an average insert size of 150 kb were picked and arrayed for C. virginica, also representing an 11.8-fold genome coverage. The C. gigas and C. virginica libraries were screened with probes derived from selected oyster genes using high-density BAC colony filter arrays. The probes
identified 4 to 25 clones per gene for C. virginica and 5 to 50 clones per gene for C. gigas. We conducted a preliminary analysis of genetic polymorphism represented in the C. gigas library. The results suggest that the degree of divergence among similar sequences is highly variable and concentrated in
intronic regions. Evidence supporting allelic polymorphism is reported for two genes and allelic and/or locus specific polymorphism
for several others. Classical inheritance studies are needed to confirm the nature of these polymorphisms. The oyster BAC
libraries are publicly available to the research community on a cost-recovery basis at 相似文献
107.
Bruno A. Buzatto Leigh W. Simmons Joseph L. Tomkins 《Evolution; international journal of organic evolution》2012,66(10):3167-3178
Polyphenic traits are widespread, but compared to other traits, relatively few studies have explored the mechanisms that influence their inheritance. Here we investigated the relative importance of additive, nonadditive genetic, and parental sources of variation in the expression of polyphenic male dimorphism in the mite Rhizoglyphus echinopus, a species in which males are either fighters or scramblers. We established eight inbred lines through eight generations of full‐sibling matings, and then crossed the inbred lines in a partial diallel design. Nymphs were isolated and raised to adulthood with ad libitum food. At adulthood, male morph was recorded for all male offspring. Using a Cockerham–Weir model, we found strong paternal effects for this polyphenic trait that could be either linked to the Y chromosome of males or an indirect genetic effect that is environmentally transmitted. In additional analyses, we were able to corroborate the paternal effects but also detected significant additive effects questioning the Cockerham–Weir analysis. This study reveals the potential importance of paternal effects on the expression of polyphenic traits and sheds light on the complex genetic architecture of these traits. 相似文献
108.
Climate of origin affects tick (Ixodes ricinus) host-seeking behavior in response to temperature: implications for resilience to climate change? 下载免费PDF全文
Climate warming is changing distributions and phenologies of many organisms and may also impact on vectors of disease-causing pathogens. In Europe, the tick Ixodes ricinus is the primary vector of medically important pathogens (e.g., Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis). How might climate change affect I. ricinus host-seeking behavior (questing)? We hypothesize that, in order to maximize survival, I. ricinus have adapted their questing in response to temperature in accordance with local climates. We predicted that ticks from cooler climates quest at cooler temperatures than those from warmer climates. This would suggest that I. ricinus can adapt and therefore have the potential to be resilient to climate change. I. ricinus were collected from a cline of climates using a latitudinal gradient (northeast Scotland, North Wales, South England, and central France). Under laboratory conditions, ticks were subjected to temperature increases of 1°C per day, from 6 to 15°C. The proportion of ticks questing was recorded five times per temperature (i.e., per day). The theoretical potential to quest was then estimated for each population over the year for future climate change projections. As predicted, more ticks from cooler climates quested at lower temperatures than did ticks from warmer climates. The proportion of ticks questing was strongly associated with key climate parameters from each location. Our projections, based on temperature alone, suggested that populations could advance their activity season by a month under climate change, which has implications for exposure periods of hosts to tick-borne pathogens. Our findings suggest that I. ricinus have adapted their behavior in response to climate, implying some potential to adapt to climate change. Predictive models of I. ricinus dynamics and disease risk over continental scales would benefit from knowledge of these differences between populations. 相似文献
109.
Matthew W Blair Natalia Hurtado Carolina M Chavarro Monica C Mu?oz-Torres Martha C Giraldo Fabio Pedraza Jeff Tomkins Rod Wing 《BMC plant biology》2011,11(1):50
Background
Sequencing of cDNA libraries for the development of expressed sequence tags (ESTs) as well as for the discovery of simple sequence repeats (SSRs) has been a common method of developing microsatellites or SSR-based markers. In this research, our objective was to further sequence and develop common bean microsatellites from leaf and root cDNA libraries derived from the Andean gene pool accession G19833 and the Mesoamerican gene pool accession DOR364, mapping parents of a commonly used reference map. The root libraries were made from high and low phosphorus treated plants. 相似文献110.
Las Heras F DaCosta RS Pritzker KP Haroon N Netchev G Tsui HW Chiu B Erwin WM Tsui FW Inman RD 《Arthritis research & therapy》2011,13(5):R163-10