The Effect of Calmodulin Antagonists on Gibberellic Acid-induced Enzyme Secretion in Barley Aleurone Layers

Calmodulin activity was detected and assayed in barley aleuronecells. The effect of calmodulin antagonists on GA₃-induced enzymesynthesis and secretion in barley aleurone layers was also investigated.These calmodulin antagonists (chlorpromazine, haloperidol) inhibitedonly GA₂-induced -amylase secretion. This inhibitory effectwas intensified after 6 h of GA₃-incubation. This leads us tosuggest that some calmodulin-controlled mechanism is involvedin GA₂-induced -amylase secretion. Hordeum vulgare L., barley aleurone cells, gibberellic acid, -amylase secretion, calmodulin, calmodulin antagonist     

森林草地转换对景观视觉效果的影响

基于景观保护的视点,定量研究了森林草地转换对景观视觉效果的影响．结果表明,中景域的可视区域比近景域和远景域大,草地建设对中景域景观视觉效果的影响也最大,因此,中景域是重要的景观保护对象．对草地内林地的可视量分析可知,各景域的可视林地多分布在400～600m高海拔上。25°以上的坡度范围内分布偏少．并探讨了草地建成后应采取的景观管理和保护对策,以增加草地景观的视觉效果．     

Motion of the Longitudinal Flagellum in Ceratium tripos (Dinoflagellida): A Retractile Flagellar Motion1

The longitudinal flagellum of Ceratium tripos moves in two dissimilar ways: undulation and retraction. The undulatory wave is planar and has a wavelength of 74.3 ± 9.6 μm and an amplitude of 14.2 ± 2.3 μm in sea water. The beat frequency is 30 Hz at 20°C, pH 8.0. The retractile motion is unique to Ceratium and is triggered by mechanical stimulation on the cell body, especially at the tip of the apical horn. When it retracts, the longitudinal flagellum folds every 4–5 μm along the flagellum. Cinematographic study showed that the flagellum folded from tip to base and was finally installed into the sulcus, a groove on the ventral side of the cell. This motion is completed in sea water within 28 msec. The retracted flagellum then re-extends and restores the undulation within a few seconds. The flagellum unfolds in the proximal portion first, then the distal, and finally the middle portion. Fixation always triggers the retraction. Scanning electron microscopy showed that the flagellum is folded and secondarily twisted in a helix. A new fiber in addition to the flagellar axoneme was found in the retracted flagellum by phase microscopy. This fiber (R-fiber) seems to contract during the retraction to fold the flagellum.     

STUDIES ON THE METABOLISM OF A SULFUR-OXIDIZING BACTERIUM II. THE SYSTEM OF CO2-FIXATION IN THIOBAC1LLUS THIOOXIDANS

1. In the early stage of CO₂-fixation by Thiobacillus thiooxidans,which was incubated aerobically in the presence of sulfur, mostpart of the fixed carbon was found in the phosphate ester fraction.
2. The fixation was inhibited by NaF, picolinic acid, PCMB, azide,dipyridyl, o-phenanthroline, monoiodoacetic acid, and arsenite,each in the concentration range where the sulfur oxidation wasnot affected strongly.
3. The crude extract of this organismcould fix CO₂ in the presenceof ATP, R-5-P and Mg⁺⁺. Most partof the fixed carbon was foundin PGA.
4. The crude extract showedthe CO₂-fixation coupled with the H₂S-oxidationin the presenceof ADP.
5. An appreciable reduction of PGA could not be detectedin thepresence of reducing systems, involving TPNH and DPNH.

(Received March 6, 1962; )     

Activities and distribution of methanogenic and methane‐oxidizing microbes in marine sediments from the Cascadia Margin

We investigated methane production and oxidation and the depth distribution and phylogenetic affiliation of a functional gene for methanogenesis, methyl coenzyme M reductase subunit A (mcrA), at two sites of the Integrated Ocean Drilling Program Expedition 311. These sites, U1327 and U1329, are respectively inside and outside the area of gas hydrate distribution on the Cascadia Margin. Radiotracer experiments using ¹⁴C‐labelled substrates indicated high potential methane production rates in hydrate‐bearing sediments [128–223 m below seafloor (mbsf)] at U1327 and in sediments between 70 and 140 mbsf at U1329. Tracer‐free experiments indicated high cumulative methane production in sediments within and below the gas hydrate layer at U1327 and in sediments below 70 mbsf at U1329. Stable tracer experiments using ¹³C‐labelled methane showed high potential methane oxidation rates in near‐surface sediments and in sediments deeper than 100 mbsf at both sites. Results of polymerase chain reaction amplification of mcrA in DNA were mostly consistent with methane production: relatively strong mcrA amplification was detected in the gas hydrate‐bearing sediments at U1327, whereas at U1329, it was mainly detected in sediments from around the bottom‐simulating reflector (126 mbsf). Phylogenetic analysis of mcrA separated it into four phylotype clusters: two clusters of methanogens, Methanosarcinales and Methanobacteriales, and two clusters of anaerobic methanotrophic archaea, ANME‐I and ANME‐II groups, supporting the activity measurement results. These results reveal that in situ methanogenesis in deep sediments probably contributes to gas hydrate formation and are inconsistent with the geochemical model that microbial methane currently being generated in shallow sediments migrates downward and contributes to the hydrate formation. At Site U1327, gas hydrates occurred in turbidite sediments, which were absent at Site U1329, suggesting that a geological setting suitable for a gas hydrate reservoir is more important for the accumulation of gas hydrate than microbiological properties.