Synthèse Facile de Pyrazines Disubstituées en 2 et 31)

Corynebacterium equi IFO 3730 was found to oxidize a wide variety of sec-alcohols, including alkanols, substituted alkanols, alkenols and cyclic alcohols, in moderate to high yields. Among them, the sec-alcohols which have longer carbon chains were oxidized more smoothly than those with smaller numbers of carbon. Although both enantiomers of unsymmetrically disubstituted carbinols were oxidized, the S form of 2-dodecanol was converted to the corresponding ketone a little faster than the other enantiomer.     

Effects of intervals between jumps or bouts on osteogenic response to loading.

Prolonged loading repetitions can diminish the mechanosensitivity of bones, and increased intervals between loading might restore sensitivity. This study was designed to investigate the effects of intervals between loadings or bouts on osteogenic response. Forty female Fisher 344 rats aged 5 wk were divided into a control group and three exercise groups: 20 jumps in a single bout with a 3-s (S3) or 30-s (S30) jump interval, or 20 jumps in 2 bouts (10 x 2) separated by a 6-h interval with a 3-s jump interval (D3). After 8 wk of training, the bone masses per body weight of the femur and tibia were significantly greater in the three exercise groups than in the control group, and these values were also greater in S30 than in S3, although they were at the same level in D3 and S3. These data suggest that a longer interval (30 s) between individual loading had more effective anabolic effects on bone than a shorter interval (3 s).     

Effect of forskolin on collagen production in clonal osteoblastic MC3T3-E1 cells

The effect of forskolin on collagen production in osteoblasts was investigated by using clonal osteoblastic MC3T3-E1 cells cultured in a-minimum essential medium containing 0.1% bovine serum albumin. Forskolin increased the adenylate cyclase activity in membranes pelleted from homogenates of the cell line in a dose-dependent manner. The drug caused a 13-fold stimulation at 10(-4) M, indicating that the compound directly acts on adenylate cyclase, leading to an increase in the intracellular cAMP content of the cells. Collagen accumulation in the cultures was elevated by one-day treatment with 5 X 10(-5) M forskolin to about twice that in the controls. The stimulation was mainly due to an elevation in collagen synthesis but not to an inhibition of intracellular collagen degradation because forskolin dose-dependently increased collagen synthesis; it also significantly increased the amount of low-molecular-weight hydroxyproline found in the cultures. Cells treated with forskolin produced mainly type I collagen, as found in bone matrix in situ, with only small amounts of other types of collagen. Furthermore, forskolin time-dependently inhibited DNA synthesis in the cells, indicating that the increase in type I collagen synthesis by forskolin was not due to stimulated cell proliferation. These results suggest that cAMP is closely linked to the differentiation of osteoblasts in vitro.     

Uncoupling of Rat Cerebral Cortical α2-Adrenoceptors from GTP-Binding Proteins by N-Ethylmaleimide

Pretreatment of membranes from rat cerebral cortex with N-ethylmaleimide (NEM) decreased [3H]-clonidine binding in a concentration-dependent manner. The Bmax values of high-affinity sites for [3H]clonidine were reduced by 50 microM NEM treatment. Treatment with 500 microM NEM diminished the sum of Bmax of both high- and low-affinity components. GTP, Na+, and Mn2+ exerted little effect on [3H]clonidine binding in NEM-treated membranes. The addition of purified GTP-binding proteins caused an increase in the binding to the membranes pretreated with 50 microM NEM, but did not increase [3H]-clonidine binding in membranes treated with 500 microM NEM. In contrast, NEM pretreatment inhibited islet activating protein (IAP)-catalyzed ADP ribosylation of membrane-bound (41,000-dalton) and purified (39,000/41,000-dalton) GTP-binding proteins. From these results, it is suggested that two or three categories of essential sulfhydryl groups are involved in the coupling between agonist, alpha 2-adrenoceptor, and GTP-binding protein. One is a highly sensitive site to NEM (a concentration range of 1-50 microM), which is probably a cysteine residue, IAP-catalyzed ADP-ribosylating site on the alpha-subunit of GTP-binding protein. Other sites have low sensitivity to NEM (a concentration range of 0.1-1 mM), and are the binding domain of agonist and/or the coupling domain of GTP-binding protein on the alpha 2-adrenoceptor. In addition, Ki-ras p21 protein may lack the capacity to couple with the alpha 2-adrenoceptor.     

Postnatal development of the ovarian bursa of the golden hamster (Mesocricetus auratus): its complete closure and morphogenesis of lymphatic stomata

The golden hamster ovarian bursa was studied by light and electron microscopy to clarify the process of its complete closure and the development of lymphatics that leads to morphogenesis of stomata. The results were as follows. 1) The bursa completely closed at 9 days of age primarily due to development of the mesotubarium superius. 2) With the closure, the ovary and bursa became closely apposed, and most of the original bursal cavity disappeared. 3) Between 9 and 12 days of age U-shaped folds of the bursal mesothelium began to invade the connective tissue of the bursa. 4) Widening of the internal angle of the U-shaped folds contributed to reappearance of the bursal cavity, and thus separation of the bursa from the ovary. It also contributed to future geometrical proximity of lymphatics to the cavity of the bursa. 5) The separation of the bursa from the ovary began as early as 12 days of age in the cephalic half of the bursa. It occurred remarkably late in the caudal half. Juxtaposition of the window portion of the bursa to the ovary remained in some adult animals. 6) Development of lymphatics in the cephalic half of the bursa was divided into two stages, before and after days 21-24 of life. In the first stage, lymphatics grew in the submesothelial connective tissue, and the framework of lymphatics was formed. In the second stage, lymphatics extended small branches to form the submesothelial plexus or lymphatic lacuna. 7) Intercellular junctions between contiguous lymphatic endothelial cells were mostly tight and desmosomelike. Open junctions were, if they occurred at all, rare. (8) A smooth-surfaced area lined with the lymphatic endothelium was found in the bursa on day 27 of life, before the initiation of ovulation. Valvelike stomal orifices were absent before the initiation of ovulation and extremely rare even after the first ovulation. They were commonly present in the bursae after the fourth ovulation, however. The process of complete closure of the ovarian bursa is very complex and may be related to the later development of the bursal mesothelium and lymphatics. Some liplike stomal orifices are of purely developmental origin. However, all valvelike stomal orifices are assumed to be formed as a result of damage to the bursal mesothelium, as well as to the submesothelial connective tissue and lymphatics, by repetition of ovulation. It is possible that liplike stomal orifices may be formed in the process of repairing the damage.     

Solubilization and Characterization of Calcitonin Gene-Related Peptide Binding Site from Porcine Spinal Cord

The binding site for calcitonin gene-related peptide (CGRP) was solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) in an active form from porcine spinal cord. 125I-labeled human alpha-CGRP (125I-CGRP) binding to the solubilized protein was determined by filtration using a GF/B glass filter. The maximal binding activity (approximately 60% of the crude membrane fraction) was obtained with 5 mM CHAPS. 125I-CGRP binding to the solubilized protein was of high affinity, saturability, and high specificity, having KD and Bmax values of 3.69 pM and 338 fmol/mg of protein, respectively. The binding activity was eluted in a single peak with a molecular mass of 400,000 daltons by gel filtration on TSK gel G4000SW. These results suggest that the solubilized protein may be responsible for the specific binding site.     

Determination of age- and exercise-dependent changes in myoglobin contents in murine skeletal and cardiac muscles

A new method was developed to determine myoglobin (Mb) contents in as least as 5 mg of murine skeletal muscles. The method was a modification of Reynafarje's spectroscopic technique and was based on the Soret absorptions at 416 and 422 nm of the muscle extract. Mb contents in the skeletal and cardiac muscles increased with age and were widely different from muscle to muscle. The contents in most of the 13 muscles examined at the 30th week of age were less than 1.5 mg/g wet muscle, but the cardiac, soleus and gracilis muscles showed exceptionally high values of 2.2-6.0 mg/g. The relative content of one muscle to the other was the same independent of differences in age, strain and sex. There was a positive correlation between the muscle Mb contents and citrate synthase activity (r = 0.930). Young male mice (5 wk-old) were endurance-trained by a gradual load-increment program on treadmill for 10 weeks (5 days/week), but the training had no effects on the Mb contents. No substantial alteration of the contents was also observed in the limbs immobilized by plaster-fixation for 4 weeks.     

Distribution of six species of bitterlings in a creek in Fukuoka Prefecture,Japan

Comparative study on the distribution of six species of bitterling in a creek in Fukuoka Prefecture was carried out. The upper part of the creek was fluvial, and the lower part stagnant.Acheilognathus lanceolatus, A. tabira subsp. (b) of Nakamura (1969),A. rhombeus andRhodeus atremius showed wide distribution in the creek throughout their life.A. limbatus seemed to be a fluvial species, andR. ocellatus smithii a lentic species. In the spawning season, however, all the species of bitterling, exceptingR. o. smithii, probably possess a common spawning ground in which mussels occur at a relatively high density. Adult females ofA. lanceolatus, A. tabira subsp. (b) andR. atremius without ripe eggs aggregated in the lower, stagnant parts of the creek. Most juveniles of these species and ofA. rhombeus seemed to grow in the lower part of the creek, and then migrate upward untill their spawning season. No species among the same phylogenetic group has the same set of the life modes (spawning season, spawning sites, aggregation of females without ripe eggs in the lower part of the creek and probability of upstream migration of 0-year-old fish toward spawning sites).     

Clerodane diterpenoids from the roots of Portulaca pilosa

Three trans-clerodane diterpenoids, pilosanol A, B and C, the last compound being a glucoside, have been isolated from the roots of Portulaca pilosa. They show a marked contrast in skeletal type with the constituents of aerial part. Evolutionary changes in the biosynthetic abilities of Portulaca species is discussed.     

REPRODUCTIVE ISOLATION AND DISTINCT POPULATION STRUCTURES IN TWO TYPES OF THE FRESHWATER SHRIMP PALAEMON PAUCIDENS

Twenty local populations of the Japanese freshwater shrimp Palaemon paucidens were electrophoretically and morphologically surveyed. Based on the diagnostic distributions of some alleles at Gpi, Mpi, Mdh-1, and Mdh-2, these populations were largely classified into two types (A and B). The A type occurred in lakes, ponds, and rivers, while the B type was observed only in rivers. Average Nei's genetic distance (D) between the two types fell into the subspecies range . The coefficient of gene differentiation, G_ST, varied considerably between the two types. In 12 populations of the A type, with a G_ST value of 0.281, nine pond and lake populations showed a higher G_ST (0.246) than the three river populations (0.151). On the other hand, G_ST was 0.036 for the eight local populations of the B type. The lower rostrum tooth number had a mode of two in type A and three in type B. Type-A populations largely varied in the upper rostrum tooth number and egg size but type B did not. Under laboratory conditions, mating frequently occurred within each type, but not between types. Furthermore, no embryonic development was observed in the few cases of intertype mating. These results indicate that the A and B types had experienced cladogenic separation with pre- or postmating isolation, whereafter the A type, under geographic isolation, underwent genetic and phenotypic differentiation, while the B type, under extensive gene flow, did not undergo differentiation.