Immunoelectron microscopic study for histamine in the gastric enterochromaffin-like cells of rats treated with the proton pump inhibitor lansoprazole

The enterochromaffin-like (ECL) cells of the gastric mucosa in animals play an important role in gastric acid secretion. They contain few granules and numerous secretory vesicles and microvesicles. They operate under the control of circulating gastrin. In the present study, we conducted an immunoelectron microscopic study for histamine (HA) in the ECL cells of rats given the proton pump inhibitor lansoprazole (LP), which is known to induce hypergastrinemia. The pre-embedding indirect immunoperoxidase procedure utilized a mouse monoclonal antibody AHA-2 against glutaraldehyde-conjugated HA. Rats received LP (50 g/kg per day, subcutaneously) over a period of a month, and developed hypertrophy of the ECL cells in the stomach. It was clearly demonstrated that HA was located to a much higher degree in the cytoplasm of ECL cells of LP-treated rats than in normal rats. HA immunoreactivity was observed in the cores of the granules and secretory vesicles of the ECL cells in all the rats, but in the LP-treated rats it was observed in the cores of the newly developed vacuoles as well. These results may suggest that HA may be actively generated in the cytoplasm of the hypertrophic ECL cells of LP-treated rats. Also suggested in the present study is that HA is instrumental in the transformation of granules into secretory vesicles and in their consequent enlargement, and that vacuoles are formed by the fusion of large secretory vesicles. Furthermore, the finding that relatively little HA immunoreactivity existed in the vacuoles may suggest that the vacuoles actively degrade superfluous secretory products (for example, HA) through enhanced autophagocytosis and/or oxidative stress. Another possibility may be that the membrane-bounded structure regarded as the vacuoles in this study might actually be an invagination structure produced as a result of successive series of exocytosis through which the secretory vesicles actively and rapidly release HA.     

Regression by ACE inhibition of arteriosclerotic changes induced by chronic blockade of NO synthesis in rats

We previously reported that chronic inhibition of nitric oxide (NO) synthesis with N(omega)-nitro-L-arginine methyl ester (L-NAME) induces vascular inflammation at week 1 and produces subsequent arteriosclerosis at week 4 and that cotreatment with an angiotensin-converting enzyme (ACE) inhibitor prevents such changes. In the present study, we tested the hypothesis that treatment with an ACE inhibitor after development of vascular inflammation could inhibit arteriosclerosis in rats. Wistar-Kyoto rats were randomized to four groups: the control group received no drugs, the 4wL-NAME group received L-NAME (100 mg x kg(-1) x day(-1)) for 4 wk, the 1wL + 3wNT group received L-NAME for 1 wk and no treatment for the subsequent 3 wk, and the 1wL + 3wACEI group received L-NAME for 1 wk and the ACE inhibitor imidapril (20 mg x kg(-1) x day(-1)) for the subsequent 3 wk. After 4 wk, we observed significant arteriosclerosis of the coronary artery (medial thickening and fibrosis) and increased cardiac ACE activity in the 1wL + 3wNT group as well as in the 4wL-NAME group, but not in the 1wL + 3wACEI group. In a separate study, we examined apoptosis formation and found that posttreatment with imidapril (20 mg x kg(-1) x day(-1)) or an ANG II AT1-receptor antagonist, CS-866 (5 mg x kg(-1) x day(-1)), induced apoptosis (TdT-mediated nick end-labeling) in monocytes and myofibroblasts appearing in the inflammatory lesions associated with a clear degradation in the heart (DNA electrophoresis). In conclusion, treatment with the ACE inhibitor after 1 wk of L-NAME administration inhibited arteriosclerosis by inducing apoptosis in the cells with inflammatory lesions in this study, suggesting that increased ANG II activity inhibited apoptosis of the cells with inflammatory lesions and thus contributed to the development of arteriosclerosis.     

Manipulation of the somatosensory cortex modulates stimulus-induced repetitive ear movements in a seizure-sensitive strain of gerbil

Some Mongolian gerbils (Meriones unguiculatus) respond to stimulation by seizures, the pattern of which changes progressively during development. We previously established a seizure-sensitive strain, MGS/Idr, in which all animals exhibit such stimulus-induced seizures. We have now noted that all adults of this strain also show repetitive backward movements of the ears at the ears at the beginning of stimulus-induced seizures, although the incidence varies with the individual. We examined whether the cerebral cortex was involved in these movements and found that electrical stimulation of an area of the somatosensory cortex elicited strong backward movement of the ear on the contralateral side, and that unilateral application of bicuculline, a GABAA receptor antagonist, induced spontaneous repetitive backward movements of the same ear. In this area, sharp waves appeared in the electrocortigram during the repetitive ear movements induced by seizure-inducing stimuli. Unilateral ablation of this area abolished stimulus-induced repetitive movements of the contralateral ear, but had no effects on those of the ipsilateral ear. These results suggest that, in certain types of seizure-susceptible subjects, it may be possible to modify stimulus-induced repetitive movements by manipulating a certain area of the somatosensory cortex which is related to these movements and that this gerbil strain may be useful in research on this subject.     

Human EVI9, a homologue of the mouse myeloid leukemia gene, is expressed in the hematopoietic progenitors and down-regulated during myeloid differentiation of HL60 cells

Evi9, a common site of retroviral integration in BXH2 murine myeloid leukemias, encodes a C2H2 zinc finger protein and is overexpressed in these leukemic cells. To investigate a possible role of EVI9 in the human hematopoietic system, we isolated the cDNA clone of the human homologue. Human EVI9, located on the chromosome 2p13 region, contains an open reading frame of 797 amino acids that is 98.7% identical to the mouse protein. RT-PCR analysis of purified human hematopoietic cells showed that EVI9 is expressed in CD34-positive myeloid precursors, B cells, monocytes, and megakaryocytes, but only weakly in T lymphocytes, suggesting that EVI9 may play an important role in hematopoiesis. Furthermore, EVI9 was down-regulated during myeloid differentiation of HL60 cells induced by all-trans-retinoic acid, whereas the expression remained during monocytic differentiation induced by phorbol 12-myristate 13-acetate. These results indicate a distinct role for EVI9 in human hematopoietic cells and suggest that EVI9 may cause leukemia through inhibition of myeloid differentiation.     

Deletion of the yhhP gene results in filamentous cell morphology in Escherichia coli

The Escherichia coli yhhP gene was predicted to encode a small hypothetical protein of 81 amino acids, the cellular function of which is not known. To gain insight into the function of this uncharacterized YhhP protein, genetic and biochemical studies were done. We first tried to express and purify the YhhP protein to prepare an anti-YhhP antiserum. Western blotting showed that the hypothetical yhhP gene is indeed transcribed and translated as a minor cytoplasmic protein. YhhP-deficient (delta yhhP) cells formed colonies poorly on a rich medium (e.g., Luria-Bertani medium) containing a relatively low concentration of NaCl, while they can grow normally either in LB containing 3% NaCl or in a synthetic medium (e.g., M9-glucose). During exponential growth in rich medium, an early step of cell division was inhibited in delta yhhP cells, forming filaments. For the YhhP-deficient filamentous cells, the FtsZ-ring formation was analyzed with immunofluorescence microscopy. The FtsZ-ring formation did not occur normally in the delta yhhP filaments, although the filamentous cells contained the FtsZ protein at a certain level comparable to that in the wild-type cells. The ftsZ gene was found to function as a multicopy suppressor of the delta yhhP mutant. Another multicopy suppressor gene was identified as the dksA gene. Provided that either the ftsZ or dksA gene was introduced into the mutant cells with its multicopy state, the resulting transformants were capable of growing in rich medium, formed wild-type short rods. These results are discussed with regard to the presumed function of this ubiquitous protein.     

Phylogenetic Position of the Subgenus Lordiphosa of the Genus Drosophila (Diptera: Drosophilidae) Inferred from Alcohol Dehydrogenase (Adh) Gene Sequences

We analyzed the phylogenetic relationship between the species of Lordiphosa and other Drosophilidae using alcohol dehydrogenase (Adh) gene sequences. The phylogenetic trees consistently show that the four species Drosophila kurokawai, D. collinella, D. stackelbergi, and D. clarofinis, which include three species groups of Lordiphosa, form a monophyletic clade. This clade is placed as a sister group to the willistoni and saltans groups of Sophophora. On the other hand, three species of Lordiphosa, D. tenuicauda, D. pseudotenuicauda, and D. acutissima, all of which belong to the tenuicauda group, are not shown to be related to the major Lordiphosa lineage. In the phylogenetic trees, these species are included into the clade comprised of Drosophila and Hirtodrosophila, although it remains uncertain whether the tenuicauda group is a monophyletic group or not. These results indicate that Lordiphosa is polyphyletic and that most of the members of the subgenus have a close relationship to the neotropical groups of Sophophora. The above conclusion is compatible with the hypothesis of Okada (Mushi [1963] 37:79–100) and Lastovka and Máca (Acta Ent Bohemoslov [1978] 75:404–420) that Lordiphosa is most closely related to Sophophora; in contrast, our results contradict the hypothesis of Grimaldi (Bull Am Mus Nat Hist [1990] 197:1–139) that Lordiphosa is a sister group to the genus Scaptomyza. Received: 12 May 1999 / Accepted: 14 April 2000     

Molecular Dissection of the Rho-associated Protein Kinase (p160ROCK)-regulated Neurite Remodeling in Neuroblastoma N1E-115 Cells

A critical role for the small GTPase Rho and one of its targets, p160ROCK (a Rho-associated coiled coil-forming protein kinase), in neurite remodeling was examined in neuroblastoma N1E-115 cells. Using wild-type and a dominant-negative form of p160ROCK and a p160ROCK-specific inhibitor, Y-27632, we show here that p160ROCK activation is necessary and sufficient for the agonist-induced neurite retraction and cell rounding. The neurite retraction was accompanied by elevated phosphorylation of myosin light chain and the disassembly of the intermediate filaments and microtubules. Y-27632 blocked both neurite retraction and the elevation of myosin light chain phosphorylation in a similar concentration-dependent manner. On the other hand, suppression of p160ROCK activity by expression of a dominant-negative form of p160ROCK induced neurites in the presence of serum by inducing the reassembly of the intermediate filaments and microtubules. The neurite outgrowth by the p160ROCK inhibition was blocked by coexpression of dominant-negative forms of Cdc42 and Rac, indicating that p160ROCK constitutively and negatively regulates neurite formation at least in part by inhibiting activation of Cdc42 and Rac. The assembly of microtubules and intermediate filaments to form extended processes by inhibitors of the Rho–ROCK pathway was also observed in Swiss 3T3 cells. These results indicate that Rho/ROCK-dependent tonic inhibition of cell process extension is exerted via activation of the actomysin-based contractility, in conjunction with a suppression of assembly of intermediate filaments and microtubules in many cell types including, but not exclusive to, neuronal cells.     

Two Long-Term Effects of Light that Control the Stability of Proteins Related to Photosynthesis during Senescence of Rice Leaves

Rate of light-saturated photosynthesis (P_max) decreased duringsenescence, with no or small changes in the initial slope ofthe light-response curve (     

Vegetation restoration by seasonal exclosure in the Kerqin Sandy Land,Inner Mongolia

Grazing control has been reported to be effective for the control of desertification in semi-arid regions. However, economic reasons often make complete inhibition of grazing (complete exclosure) difficult to carry out. Grazing control has been applied to the Kerqin Sandy Lands, Inner Mongolia, China, by means of seasonal exclosure, whereby grazing is allowed from November to April. The harvesting of hay is also allowed once during September - October. The aim of the reported study was to evaluate the effectiveness of this seasonal exclosure on vegetation restoration. Species compositional data were obtained from 356 quadrats and ordinated by Detrended Correspondence Analysis (DCA). Ordination indicated that landform was the most important factor influencing the species composition of the vegetation. Regardless of landform and type of grazing control, however, vegetation coverage, vegetation height and species richness were higher at sites where grazing had been controlled, than at sites lacking any control. Perennial species were dominant at the former while annual species were dominant at the latter. Both shrub and tree species were quite rare at the sites where seasonal exclosure had been carried out. It is concluded that seasonal exclosure is sufficient to restore and maintain grassland vegetation in and around the study area. When shrubby or tree vegetation is needed for reasons such as fixing sands or preventing sand dune remobilization, complete exclosure is recommended.