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Historical time series for average human height exhibit short- and medium-term cycles that can be associated with business cycles in the 19th and 20th century. Using spectral analysis, we calculate the proportion of cyclical fluctuations in height series attributable to economic cycles. We also analyze the extent to which these cyclical phenomena change over time. In the U.S., the association between height cycles and business cycles was weaker among richer segments of the society, and weaker among men than among women. Additionally, the relationship diminished over time, probably with the rich preceding the population at large.  相似文献   

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We describe the synthesis of a novel type of mRNA template and its use in the preparation of mRNA–protein fusions. A light-induced psoralen crosslinking reaction was used to attach a puromycin-containing oligonucleotide to the 3′-end of an mRNA template. The photo-crosslinked template was found to undergo efficient mRNA–protein fusion formation in rabbit reticulocyte lysate. Fusion formation was subsequently tested with templates carrying puromycin linkers of different length and chemical composition. Short linkers with multiple triethyleneglycol phosphate building blocks allowed the most efficient fusion formation under a wide range of salt conditions. The present method simplifies the preparation of mRNA–protein fusions and thus significantly accelerates the in vitro protein evolution procedure which involves repetitive cycles of fusion production and selection.  相似文献   

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A simple, direct method for the detection of DNA–protein interaction was developed with electrochemical methods. Single-stranded DNA (ss-DNA) probes were prepared through the chemical bonding of an oligonucleotide to a polymer film bearing carboxylic acid groups, and double-stranded DNA (ds-DNA) probes were prepared through hybridization of the complementary sequence DNA on the ss-DNA probe. Impedance spectroscopy and differential pulse voltammetry (DPV) distinguished the interaction between the DNA probes with mouse Purβ (mPurβ), an ss-DNA binding protein, and with Escherichia coli MutH, a ds-DNA binding protein. Impedance spectra obtained before and after the interaction of DNA probes with these proteins clearly showed the sequence-specific ss-DNA preference of mPurβ and the sequence-specific ds-DNA preference of MutH. The concentration dependence of proteins on the response of the DNA probes was also investigated, and the detection limits of MutH and mPurβ were 25 and 3 μg/ml, respectively. To confirm the impedance results, the variation of the current oxidation peak of adenine of the DNA probe was monitored with DPV. The formation constants of the complexes formed between the probe DNA and the proteins were estimated based on the DPV results.  相似文献   

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The first family planning clinic in Louisiana was started in 1965 in Lincoln Parish, offering services to medically indigent residents. 719 women of the total 1055 eligible residents were contacted and 57% attended the clinic. Only 12% of the clinic patients come to the clinic on their own initiative, showing the importance of outreach. 74% of clinic attendees were aged 24 or younger. 44.9% had had 1 birth, 18.4% birth, and 36.7% had had 3 or more birth. Over 43% had experienced more than 1 out of wedlock birth. Between 1966 and 1967 there was a 21.6% decrease in births to medically indigent women 19 or younger, a 52.1% decrease for those 20-24, and 37.5% for those 25-29, compared with 16%, 7.9% and 7.7% for control parishes. There was a 30% drop in total out of wedlock births in 1967 in the study area. In 1967 the illegitimacy ratio dropped from 156.6 per 1000 to 121.4. The woman of second or higher parity were the most affected by the program since only women who had ever been married or pregnant were allowed to participate in the program.  相似文献   

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The marsupial genus Antechinus is a group of small carnivorous marsupials from the order Dasyuromorphia (Family Dasyuridae) and is found in eastern Australia. The life history of all species in the genus is characterized by a complex, but highly synchronized life cycle in both sexes, culminating in a short mating period followed by total male mortality (semelparity). The breeding season is defined by a specific rate of increase in photoperiod, which is different for each species. In Antechinus spp., male mortality is due to the effects of high free testosterone and cortisol levels on many organ systems. Unusually, spermatogenesis is complete before testosterone levels begin to rise at the winter solstice. In males, low sperm counts have been compensated for by high proportions of sperm reaching the isthmus of the female reproductive tract and long-term storage in the crypts. The females survive to rear their young and may mate again in their second year. Gestation lasts from 26 to 34 days, depending on the species. However, developmental arrest can occur at several stages during embryogenesis, elongating the apparent gestation duration by several days. Several species have strong female sex biases in their litters. The high degree of life history synchrony and the cascade of endocrine-driven physiological events that result in male death are unusual physiological characteristics for mammals. Suggestions why semelparity may have evolved in Antechinus are discussed.  相似文献   

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Loop–loop tertiary interactions play a key role in the folding and catalytic activity of natural hammerhead ribozymes. Using a combination of NMR spectroscopy, site-directed mutagenesis and kinetic and infectivity analyses, we have examined the structure and function of loops 1 and 2 of the (+) and (–) hammerheads of chrysanthemum chlorotic mottle viroid RNA. In both hammerheads, loop 1 is a heptanucleotide hairpin loop containing an exposed U at its 5′ side and an extrahelical U at its 3′-side critical for the catalytic activity of the ribozyme in vitro and for viroid infectivity in vivo, whereas loop 2 has a key opened A at its 3′-side. These structural features promote a specific loop–loop interaction motif across the major groove. The essential features of this tertiary structure element, base pairing between the 5′ U of loop 1 and the 3′ A of loop 2, and interaction of the extrahelical pyrimidine of loop 1 with loop 2, are likely shared by a significant fraction of natural hammerheads.  相似文献   

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In budding yeast, accurate chromosome segregation requires that one and only one kinetochore assemble per chromosome. In this paper, we report the use of DNA–protein crosslinking and nondenaturing gel analysis to study the structure of CBF3, a four-protein complex that binds to the essential CDEIII region of Saccharomyces cerevisiae centromeres. We find that three subunits of CBF3 are in direct contact with CDEIII over a region of DNA that spans 80 bp. A highly asymmetric core complex containing p58CTF13 p64CEP3 and p110NDC10 in direct contact with DNA forms at the genetically defined center of CDEIII. This core complex spans ~56 bp of CEN3. An extended complex comprising the core complex and additional DNA-bound p110NDC10 also forms. It spans ~80 bp of DNA. CBF3 makes sequence-specific and -nonspecific contacts with DNA. Both contribute significantly to the energy of CBF3–DNA interaction. Moreover, important sequence-specific contacts are made with bases that are not conserved among yeast centromeres. These findings provide a foundation for understanding the organization of the CBF3–centromere complex, a structure that appears to initiate the formation of microtubule attachment sites at yeast kinetochores. These results also have implications for understanding centromere-binding proteins in higher cells.  相似文献   

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