363 research outputs found
Enhancement of Spin Susceptibility near Charge-Ordering Transition in a Two-Dimensional Extended Hubbard Model
Based on the non-skeleton diagrammatic expansion satisfying the
compressibility and spin-susceptibility sum rules, we investigate static charge
and spin responses in a two-dimensional extended Hubbard model with the
nearest-neighbor Coulomb repulsion in the vicinity of its charge-ordering
transition point. In this expansion, we can calculate approximate charge and
spin response functions by systematic inclusion of vertex corrections, from
which we obtain the uniform susceptibility equal to the so-called q-limit of
the response function and the second-order transition point as a divergent
point in the same response function at some finite wave-number vector. It is
shown that the reentrant charge-ordering transition, which has already been
observed in the random-phase approximation (RPA), remains to take place even
though the vertex corrections are included beyond the RPA. As a prominent
effect of the vertex corrections, we find that the uniform spin susceptibility
is enhanced due to charge fluctuations developing toward the charge-ordering
transition. We give a qualitative comparison of this enhanced spin
susceptibility with the experimental results on the quasi-two-dimensional
organic conductors, together with its explanation in the Landau's Fermi-liquid
theory.Comment: 24 pages, 8 figure
Studies on the Polypeptides of Poxvirus I. Comparison of Structural Polypeptides in Vaccinia, Cowpox and Shope Fibroma Viruses
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Neurosecretory Protein GL Induces Fat Accumulation in Chicks.
We recently found a previously unidentified cDNA in chicken hypothalamus which encodes the precursor for neurosecretory protein GL (NPGL). A previous study showed that intracerebroventricular (i.c.v.) infusion of NPGL caused body mass gain in chicks. However, it was not clear which part(s) of the body gained mass. In the present study, we investigated which tissues increased in mass after chronic i.c.v. infusion of NPGL in chicks. We found that NPGL increased the masses of the liver, abdominal fat, and subcutaneous fat, while NPGL did not affect the masses of muscles, including pectoralis major, pectoralis minor, and biceps femoris. Oil Red O staining revealed that fat deposition had occurred in the liver. In addition, the size of the lipid droplets in the abdominal fat increased. Furthermore, we found an upregulation of lipogenesis and downregulation of lipolysis in the abdominal fat, but not in the liver. These results indicate that NPGL is involved in fat storage in chicks
Persistence of Genomes of Both Herpesvirus of Turkeys and Marek's Disease Virus in a Chicken T-Lymphoblastoid Cell Line
Localization and function of neurosecretory protein GM, a novel small secretory protein, in the chicken hypothalamus.
Recently, we discovered a novel cDNA encoding the precursor of a small secretory protein, neurosecretory protein GL (NPGL), in the hypothalamic infundibulum of chickens. NPGL plays an important role in the regulation of growth and feeding. A database search indicated that the NPGL gene has a paralogous gene: neurosecretory protein GM (NPGM), also in chickens. We identified cDNA encoding the NPGM precursor in chickens. Morphological analysis showed that NPGM-containing cells are specifically localized in the medial mammillary nucleus (MM) and infundibular nucleus (IN) in the hypothalamus. In addition, we found that NPGM and NPGL are co-localized, especially in the MM. The expression levels of NPGM mRNA gradually decreased during post-hatch development, in contrast to those of NPGL mRNA. Moreover, we investigated the relationship between NPGM and other known factors. NPGM was found to be produced in histaminergic neurons in the MM. NPGM and histidine decarboxylase, a histamine-producing enzyme, displayed similar expression patterns during post-hatch development. Acute intracerebroventricular injection of NPGM decreased food intake, similar to the effect of histamine. To our knowledge, this is the first report of the localization and function of NPGM in the brain of vertebrates. These results will further advance the understanding mechanisms underlying energy homeostasis
A Lymphoblastoid Cell Line Dually Infected with Marek's Disease Virus and Avian Leukosis Virus
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