Phylogenetic analysis of the core histones H2A, H2B, H3, and H4

The class I cytokine receptors consist of multiple subunits without any intrinsic enzymatic activities. Receptors for a subset of cytokines with overlapping biological activities often share a common receptor subunit with a signaling function. Each receptor regulates its specific signaling pathways, as well as common pathways depending on the target cell type.     

H. H. Goddard and the immigrants.

Responds to comments by D. D. Dorfman (see record 1982-25821-001), D. Gersh (see record 1982-25825-001), R. J. Herrnstein (1981), and L. J. Kamin (see record 1982-25833-001) on the source of data cited in H. H. Goddard's (1917) article on mental tests with immigrants. An attempt is made to clarify what the cited data about the immigrants represent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

H,K-ATPase

NMR studies have been used to examine conformational effects in thyrotropin-releasing hormone (TRH), the epimer incorporating D-His, and their analogues where trans- and cis-4-hydroxy-L-proline replace L-proline (Pro). In all six compounds the observed overall conformation of the major conformer around the Pro-His amide bond, and the observed increase of the cis/trans ratio between the conformers when L-His is replaced by D-His, can be accommodated by assuming that a ten-membered ring is formed by hydrogen bonding between the N-H of the Pro carboxamide function and the N pi-atom of the His imidazole nucleus.     

The vertebrate linker histones H1 zero, H5, and H1M are descendants of invertebrate "orphon" histone H1 genes

We investigated the evolutionary history of the divergent vertebrate linker histones H1 zero, H5, and H1M. We observed that the sequence of the central conserved domain of these vertebrate proteins shares characteristic features with histone H1 proteins of plants and invertebrate animals which otherwise never appear in any vertebrate histone H1 protein. A quantitative analysis of 58 linker histone sequences also reveals that these proteins are more similar to invertebrate and plant histone H1 than to histone H1 of vertebrates. A phylogenetic tree deduced from an alignment of the central domain of all known linker histones places H1 zero, H5, and H1M in close vicinity to invertebrate sperm histone H1 proteins and to invertebrate histone H1 proteins encoded by polyadenylated mRNAs. We therefore conclude that the ancestors of the vertebrate linker histones H1 zero, H5, and H1M diverged from the main group of histone H1 proteins before the vertebrate type of histone H1 was established in evolution. We discuss this observation in the general context of linker histone evolution.     

Erythroid marrow activity and hemoglobin H levels in hemoglobin H disease

BACKGROUND: Active noise reduction (ANR) is an electronic system that works by continuous sampling of noise inside the earshell of the headset with a small microphone. This signal is inverted in phase through the headset speaker, thus reducing noise levels by destructive interference of the acoustic field. The system provides good low-frequency noise attenuation, but aircrew differ in their subjective opinion of ANR. The present study is an attempt to provide an objective assessment of the effect of ANR on noise levels at the tympanic membrane. METHODS: There were 7 subjects with normal ears who were placed in an environment of recorded noise from a BO-105 helicopter. A microphone probe was inserted to within 5 mm of the tympanic membrane of each subject's right ear. Noise levels in the ear were measured without a headset and with two different ANR headsets. Measurements were performed with and without the ANR system on, and with and without white noise through the headset communication system. The white noise was used to simulate aircraft communication noise. RESULTS: The two headsets tested had differing levels of passive and active attenuation. The ANR system produced a substantial low-frequency attenuation. However, noise levels in the mid frequencies increased somewhat when the ANR system was switched on. This effect was augmented when white noise in the communications system was introduced, particularly for one of the two headsets. Low-frequency noise attenuation of ANR systems is substantial, but an increased mid- and high-frequency noise level caused by the ANR may affect both communication and overall noise levels. Our data provide advice on what factors should be taken into account when ANR is evaluated for use in an aviation operational environment.