Glucagon-related peptides in the rat hypothalamus

Summary Immunohistochemically, nerve fibers and terminals reacting with anti-N-terminal-specific but not with anti-C-terminal-specific glucagon antiserum were observed in the following rat hypothalamic regions: paraventricular nucleus, supraoptic nucleus, anterior hypothalamus, arcuate nucleus, ventromedial hypothalamic nucleus and median eminence. Few fibers and terminals were demonstrated in the lateral hypothalamic area and dorsomedial hypothalamic nucleus. Radioimmunoassay data indicated that the concentration of gut glucagon-like immunoreactivity was higher in the ventromedial nucleus than in the lateral hypothalamic area. In food-deprived conditions, this concentration increased in both these parts. This was also verified in immunostained preparations in which a marked enhancement of gut glucagon-like immunoreactivity-containing fibers and terminals was observed in many hypothalamic regions. Several immunoreactive cell bodies were found in the ventromedial and arcuate nuclei of starved rats. Both biochemical and morphological data suggest that glucagon-related peptides may act as neurotransmitters or neuromodulators in the hypothalamus and may be involved in the central regulatory mechanism related to feeding behavior and energy metabolism.     

Photoreception in pineal organs of larval and adult lampreys,Lampetra japonica

A comparative study of the larval and adult pineal organs, which are sensitive to incident light, was carried out in the river lamprey Lampetra japonica, using intracellular recording from the pineal photoreceptors. The tissue overlying the larval pineal organ is transparent, whereas that over the adult pineal is translucent. The optical density of this oval pineal window in the adult lamprey was 1.2. In order to elucidate the early development of the larval pineal, the ratio r of the diameter (micron) of the pineal to the body-length (cm) was measured. The value of r was 62.5 in a small larva of 2.8 cm, 29.7 in a larger one of 14.3 cm, and 9.3 in an adult of 54 cm body-length. The intracellular response to light of the larval pineal was a hyperpolarization, showing fundamentally the same pattern as that of the adult pineal. It was possible to record a typical response even from the pineal of the smallest larva, 2.8 cm in body length, used in this study. The intensity-amplitude relationship was analysed after Naka-Rushton's hyperbolic equation. The value of sigma of isolated larval pineals was 0.88 log unit higher than that of adults. The value of n was larger in larvae, suggesting a sensitive reaction to changing photic stimulus. The spectral sensitivity was compared. The peak was at 505 nm in the larva, but 525 nm in the adult. A change of visual pigment in the pineal during metamorphosis is suggested.     

Isolation of virus causing hemorrhagic fever with renal syndrome (HFRS) through a cell culture system

Twenty-three rat lung specimens collected in outbreaks of hemorrhagic fever with renal syndrome (HFRS) in three medical institutions were inoculated onto the VERO-E6 cell monolayers. After several blind passages, an agent growing serially in the cell cultures and reacting specifically with known HFRS-positive sera was isolated from two of these specimens. The two isolates were antigenically identical each other. The agent, named strain SR-11, was identified as the causative virus of HFRS by its antigenic identity with E6 cell-adapted HFRS virus, Hantaan 76-118 strain, and the specific reactions with sera from various HFRS cases.     

Distribution and biosynthesis of aminopeptidase N and dipeptidyl aminopeptidase IV in rat small intestine

The regional, cellular and subcellular distribution patterns of aminopeptidase N and dipeptidyl aminopeptidase IV were examined in rat small intestine. Aminopeptidase N of brush border membrane had maximal activity in the upper and middle intestine, while dipeptidyl aminopeptidase IV had a more uniform distribution profile with relatively high activity in the ileum. Along the villus and crypt cell gradient, the activity of both enzymes was maximally expressed in the mid-villus cells. However there was substantial dipeptidyl aminopeptidase IV activity in the crypt cells. Both enzymes were primarily associated with brush border membranes in all segments, however, in the proximal intestine, a significant amount of dipeptidyl aminopeptidase IV activity was associated with the cytosol fraction. The cytosol and brush border membrane forms of dipeptidyl aminopeptidase IV were immunologically identical and had the same electrophoretic mobility on disc gels. In contrast, the soluble and brush border membrane-bound forms of aminopeptidase N were immunologically distinct. When the total amount of aminopeptidase N and dipeptidyl aminopeptidase IV was determined by competitive radioimmunoassay, there were no regional or cellular differences in specific activity (enzyme activity/mg of enzyme protein) of either enzyme in brush border membrane and homogenate. The specific activity of both enzymes in a purified Golgi membrane fraction as measured by radioimmunoassay was about half that of the brush border membrane fraction. These results suggest that (1) aminopeptidase N and dipeptidyl aminopeptidase IV have different regional, cellular and subcellular distribution patterns; (2) there are enzymatically inactive forms of both enzymes present in a constant proportion to active molecules and that (3) a two-fold activation of precursor enzyme forms occurs during transfer from the Golgi membranes to the brush border membranes.     

Protein Patterns of Growing and Starved Cells of a Marine Vibrio sp.

Fingerprint protein patterns were produced by two-dimensional polyacrylamide electrophoresis on lysed cells of a Vibrio sp., Ant-300, which were prepared from growing and starved cultures. The cells were labeled with [³⁵S]methionine during growth and subsequently starved for up to 30 days. Samples were taken at selected time points representing stages in the starvation-survival process. Unlabeled starved cells were allowed to recover in the presence of [³⁵S]methionine to determine protein changes associated with the recovery from starvation. All growth conditions produced similar protein fingerprints; however, some protein spots disappeared, whereas others were seen only during starvation.     

Bacterial Activity Associated with the Decomposition of Woody Substrates in a Stream Sediment

Ground bark and heartwood from Alnus rubra and Pseudotsuga menziesii were added to a muddy sediment from a small Oregon stream and incubated in situ. Carbon dioxide and methane production rates were increased by all amendments, the biggest increase being shown with A. rubra wood. Except for sediment amended with A. rubra wood, nitrogen fixation rates from all treatments (including the control) were approximately 0.1 nmol/g per h throughout the 6-month study period. Contrary to expectations, neither bark had a noticeable adverse effect on microbial activity, but the A. rubra wood promoted nitrogen fixation. These results help to explain the faster rate of decomposition of A. rubra wood in water compared with that of P. menziesii described in the literature. The uptake kinetics of glucose (V_max) did not follow the same pattern as gas evolution.     

Stimulation of eicosapentaenoic acid metabolism in washed human platelets by 12-hydroperoxyeicosatetraenoic acid

Washed human platelets were not able to convert eicosapentaenoic acid (EPA) to thromboxane B3 (TXB3) and 12-hydroxyeicosapentaenoic acid (AA) to washed human platelets induced conversion of EPA to TXB3 and 12-HEPE. Esculetin, a specific inhibitor of 12-lipoxygenase, prevented the effect of AA, but cyclooxygenase inhibitor did not. The conversion of AA to TXB2 was not affected by the same dose of esculetin. These data suggest that products of AA formed by 12-lipoxygenase in human platelets have stimulatory effects on EPA metabolism. When AA was preincubated with washed human platelets, its effect on EPA conversion was reduced, suggesting that a labile product of AA formed by 12-lipoxygenase is involved in the facilitation of EPA metabolism. Addition of 12-hydroperoxyeicosatetraenoic acid directly to washed human platelets caused dose-dependent synthesis of TXB3 and 12-HEPE, while addition of 12-hydroxyeicosatetraenoic acid had no effect. Thus, 12-hydroperoxyeicosatetraenoic acid formed from AA promotes the metabolism of EPA in washed human platelets.     

Diurnal K+ and Anion Transport in Phaseolus Pulvinus

Diurnal movement of Phaseolus leaf is caused by deformationof the laminar pulvinus located at the joint of the leaf bladeand the petiole. The plants were cultured in solutions withvarious ion compositions, and changes of K⁺, Na⁺, Ca²⁺, Mg²⁺,Cl^–, NO₃– and P₁ concentrations both in the upperand lower parts of the laminar pulvinus were measured. Culturein 10 mM KCl solution caused an increase in K⁺ and Cl^–concentrations both in the upper and lower parts without anysignificant change in the concentration of NO₃^–; culturein 10 mM KNO₃ solution caused an increase in K⁺ and NO₃^–concentration without any significant change in the concentrationof Cl^–; and culture in 10 mM KH₂PO₄ solution caused anincrease in K⁺ and P₁ concentrations without any significantchange in the concentrations of NO₃- and Cl^–. K⁺ moved from the upper to lower parts or from the lower toupper parts diurnally in all plants cultured in any solutionmentioned above. The main inorganic anion that accompanied thisK⁺ movement was Cl^– in KCl solution, and NO₃^– inKNO₃ solution. When the seedlings were cultured in distilledwater or in KH₂PO₄ solution, neither Cl^– NO₃^– norP₁ accompanied this K⁺ movement. In these cases, mainly H⁺ and/ororganic anions are supposed to move in exchange for and/or incombination with K⁺ movement. (Received November 8, 1982; Accepted June 13, 1983)