105 research outputs found

    A comparative study of the egg-white proteins of passerine birds

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    The avian order Passeriformes contains more than 5000 of the approximately 8600 species of living birds….https://elischolar.library.yale.edu/peabody_museum_natural_history_bulletin/1031/thumbnail.jp

    The relationships of the β€œwren-thrush”, Zeledonia coronata Ridgway

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    Comparisons of the electrophoretic pattern of the egg-white proteins of Zeledonia coronata with the patterns of most groups of passerine birds indicate that this species is not a thrush, but a nine-primaried oscine , probably allied most closely to, and possibly a member of, the wood warblers (Parulidae of Wetmore, 1960). Investigation of the taxonomic history of Zeledonia suggests that an early combination of bias, errors, and incomplete comparative studies conspired to divert the attention of later investigators from the ample anatomical evidence indicating the true relationships of Zeledonia

    The relationships of the Yellow-breasted Chat (Icteria virens) and the alleged slowdown in the rate of macromolecular evolution in birds

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    The taxonomic relationships of the Yellow-breasted Chat (Icteria virens) have been uncertain since its discovery more than 200 years ago. Although usually considered to be a New World wood warbler (Parulini) it possesses structural and behavioral characteristics that seem aberrant in comparison with the typical members of that group. The relationships of Icteria were investigated by comparing its single-copy DNA sequences with those of other New World nine-primaried oscines and representatives of other oscine families, using the technique of DNA-DNA hybridization. The data indicate that Icteria is a paruline warbler and it should continue to be included within that group. The study of Icteria provided the basis for an examination of the suggestion by several authors that the proteins of birds and, by extension, their DNAs, evolve more slowly than do those of other animals. Evidence is presented indicating that the alleged differences are due, at least in part, to differences in the human perception of the boundaries of taxonomic categories in birds versus most other organisms. Birds are taxonomically oversplit at all supraspecific levels, but small, nocturnal mammals and other groups are probably overlumped at all levels. The lack of equivalence between the taxonomic categories of birds and those of other animals results in an erroneous evaluation of their rates of macromolecular evolution. DNA hybridization data indicate that the vireos (Vireoninae) are not closely related to the wood warblers, or to other New World nine-primaried oscines. We have shown elsewhere that the vireos are members of a large, varied corvine assemblage

    Divergence of the single-copy DNA sequences of the Western Grebe (Aechmophorus occidentalis) and Clark’s Grebe (A. clarkii), as indicated by DNA-DNA hybridization

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    Single-copy nuclear DNA sequences of individuals of Aechmophorus occidentalis and A. ciarkii were compared by DNA-DNA hybridization. In each of three experimental sets the average thermal stability of homoduplex and within-species DNA-DNA hybrids did not differ, but the between-species DNA-DNA hybrids dissociated at an average temperature 0.57Β°C below the median melting temperature of homoduplex and within-species hybrids. The difference was highly significant in all three sets. The median DNA sequence distance between A. occidentalis and A. clarkii is comparable to such distances between other closely related congeneric species

    Dopamine receptors in GtoPdb v.2023.1

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    Dopamine receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Dopamine Receptors [373]) are commonly divided into D1-like (D1 and D5) and D2-like (D2, D3 and D4) families, where the endogenous agonist is dopamine

    The role of DNA microarrays in Toxoplasma gondii research, the causative agent of ocular toxoplasmosis

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    Ocular toxoplasmosis, which is caused by the protozoan parasite Toxoplasma gondii, is the leading cause of retinochoroiditis. Toxoplasma is an obligate intracellular pathogen that replicates within a parasitophorous vacuole. Infections are initiated by digestion of parasites deposited in cat feces or in undercooked meat. Parasites then disseminate to target tissues that include the retina where they then develop into long-lived asymptomatic tissue cysts. Occasionally, cysts reactivate and growth of newly emerged parasites must be controlled by the host’s immune system or disease will occur. The mechanisms by which Toxoplasma grows within its host cell, encysts, and interacts with the host’s immune system are important questions. Here, we will discuss how the use of DNA microarrays in transcriptional profiling, genotyping, and epigenetic experiments has impacted our understanding of these processes. Finally, we will discuss how these advances relate to ocular toxoplasmosis and how future research on ocular toxoplasmosis can benefit from DNA microarrays
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