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Cosmid vectors containing a dominate selectable marker (ble) for complementation cloning of genes in Chlamydomonas reinhardtii were created. The usefulness of these vectors, which differ in the orientation of the ble cassette, was demonstrated by transforming C. reinhardtii to phleomycin resistance, by constructing a large library (approximately 5 x 10(5) recombinants) in one of them using DNA from a C. reinhardtii mutant, and by transforming C. reinhardtii with recombinant cosmid clones and pools. 相似文献
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Sham HL Betebenner DA Rosenbrook W Herrin T Saldivar A Vasavanonda S Plattner JJ Norbeck DW 《Bioorganic & medicinal chemistry letters》2004,14(10):2643-2645
The HIV protease inhibitor ABT-378 (lopinavir) has a six-member cyclic urea in the P-2 position. A series of analogues in which the six-member cyclic urea is replaced by various heterocycles was synthesized and the structure-activity relationships explored. 相似文献
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Anita Narwani Markos A. Alexandrou James Herrin Alaina Vouaux Charles Zhou Todd H. Oakley Bradley J. Cardinale 《PloS one》2015,10(9)
Phytoplankton species traits have been used to successfully predict the outcome of competition, but these traits are notoriously laborious to measure. If these traits display a phylogenetic signal, phylogenetic distance (PD) can be used as a proxy for trait variation. We provide the first investigation of the degree of phylogenetic signal in traits related to competition in freshwater green phytoplankton. We measured 17 traits related to competition and tested whether they displayed a phylogenetic signal across a molecular phylogeny of 59 species of green algae. We also assessed the fit of five models of trait evolution to trait variation across the phylogeny. There was no significant phylogenetic signal for 13 out of 17 ecological traits. For 7 traits, a non-phylogenetic model provided the best fit. For another 7 traits, a phylogenetic model was selected, but parameter values indicated that trait variation evolved recently, diminishing the importance of common ancestry. This study suggests that traits related to competition in freshwater green algae are not generally well-predicted by patterns of common ancestry. We discuss the mechanisms by which the link between phylogenetic distance and phenotypic differentiation may be broken. 相似文献
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MARTINE RUBILIANI-DUROZOI CLAUDIO RUBILIANI GENEVIÈVE G. PAYEN 《Invertebrate reproduction & development.》2013,57(2):107-120
A histological study of the gonads and androgenic glands of Carcinus parasitized with Sacculina carcini showed no correlation between the degree of infestation of the gonads by the roots of the parasite and the progressive inhibition of the course of male and female gametogeneses. Also, no correlation could be observed between the degree of degeneration of the androgenic glands and that of the testes. Modifications in parasitized crab testes essentially involve a degeneration of the mesoderm tissue of the germinative zone; primary gonia become pycnotic after an abnormal development; germ cells already engaged in spermatogenesis become blocked in prophase of meiosis; and ultimately, the testis becomes empty. Progressive degeneration of the androgenic glands, after an initial hypertrophy that starts as early as the internal Sacculina stage, seems related to the disorganization of the neurosecretory centers of the host. Arrest of spermatogenesis at a more or less advanced stage is probably the result of an imbalance in neurohormonal controls acting directly on the germinative zone or indirectly via the androgenic glands. At the level of the ovaries, parasitic infestation leads to inhibition of the second phase of vitellogenesis possibly due to an abnormality in the organization of the vitellogenic follicles. Hormonal imbalances related to the presence of the parasite appear to be responsible for these phenomena. 相似文献
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Gagliardi-Seeley Jennifer Bakker Aaron Burke Megan Glenn Melissa Herrin Alyssa 《Journal of Ethology》2021,39(2):259-263
Journal of Ethology - In many monogamous species, sexual selection often occurs through female mate choice, which is usually based on male characteristics such as size. However, the presence of a... 相似文献
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Quantitative studies of Mn(2+)-promoted specific and non-specific cleavages of a large RNA: Mn(2+)-GAAA ribozymes and the evolution of small ribozymes 下载免费PDF全文
Manganese (Mn2+) promotes specific cleavage at two major (I and III) and four minor (II, IV, V and VI) sites, in addition to slow non-specific cleavage, in a 659-nucleotide RNA containing the Cr.LSU group I intron. The specific cleavages occurred between G and AAA sequences and thus can be considered Mn2+-GAAA ribozymes. We have estimated rates of specific and non-specific cleavages under different conditions. Comparisons of the rates of major-specific and background cleavages gave a maximal specificity of approximately 900 for GAAA cleavage. Both specific and non-specific cleavages showed hyperbolic kinetics and there was no evidence of cooperativity with Mn2+ concentration. Interestingly, at site III, Mg2+ alone promoted weak, but the same specific cleavage as Mn2+. When added with Mn2+, Mg2+ had a synergistic effect on cleavage at site III, but inhibited cleavage at the other sites. Mn2+ cleavage at site III also exhibited lower values of K (Mn2+ requirement), pH-dependency and activation energy than did cleavage at the other sites. In contrast, the pH-dependency and activation energy for cleavage at site I was similar to non-specific cleavage. These results increase our understanding of the Mn2+-GAAA ribozyme. The implications for evolution of small ribozymes are also discussed. 相似文献