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21.
Birefringence in endosperm mitosis 总被引:10,自引:0,他引:10
22.
Shinya Matsuda 《Coral reefs (Online)》1989,7(4):185-195
Observations were made on the succession and growth rates of crustose coralline algae growing in situ on artificial substrata in a shallow fore-reef environment on Ishigaki Island, Ryukyu Islands. Succession in well-illuminated environments manifests itself as a gradual replacement of species having very thin thalli by those having larger and thicker thalli. The species Porolithon onkodes, Paragoniolithon conicum and Lithophyllum insipidum achieved dominance by competitive interactions of overgrowing margins. The thicker species recruit quickly (within the first few months), but because of their slow growth rate do not displace the pioneer species that have very thin thalli until after the latter begin to die. Regardless of seasonal temperature fluctuations, which exceed 10 °C, the coralline algal succession is the same for each season. The maximum lateral growth rates of the major species range between 2.9 and 3.9 mm/month. Vertical growth rates of Porolithon onkodes, the thickest species, are the most rapid (more than 2 mm/year at maximum) relative to those of other species. Accretion rates of entire coralline algal cover on ungrazed substrata range from 1.0 to 1.2 mm/year (not allowing any lag time for recruitment), whereas those of grazed substrata are lower. These results are consistent with species which are ecological equivalents and live in similar environments on Caribbean reefs. 相似文献
23.
H Bito N Ohishi I Miki M Minami T Tanabe T Shimizu Y Seyama 《Journal of biochemistry》1989,105(2):261-264
Leukotriene A4 hydrolase was purified to apparent homogeneity from the guinea pig lung. The molecular weight was determined to be 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme exhibited two active forms with different pI values (5.7 and 5.4) depending on the presence or absence of SH-reducing reagents during purification procedures. No significant differences were observed between both forms of the enzyme as regards the catalytic properties. The N-terminal 20 amino acid sequence (PEVVDTXSLASPATVXRTKH) showed a 90% identity to the human enzyme with a constitutive substitution of Ile-3 and Ser-14 (human) by Val-3 and Thr-14 (guinea pig), respectively. 相似文献
24.
Masayuki Nakamichi Fumiaki Cho Tetsuhiro Minami 《Primates; journal of primatology》1990,31(2):213-224
This study documents age-related changes in the interactions of wild-born cynomolgus macaque mothers and their infants living
in individual cages during the first 14 weeks of infant life. Body contact between mother and infant, maternal holding, and
infant sucking were found to decrease, and the mothers showed an increased frequency of aggression toward their infants with
age. These results were broadly similar to those reported for mother-infant interactions in other macaques living in social
groups. Nevertheless, a clear difference between the present cynomolgus macaques and other macaques in social groups was apparent.
The cynomolgus macaque mothers tended to permit their infants to move about freely without displaying maternal protectiveness
such as restraint or retrieval, unlike other macaque mothers in social groups. Such maternal behaviors might derive from the
experience of living in individual cages for many years and the relative safety of living in individual cages. The lack of
maternal restraint and retrieval could be responsible for the observed sex differences in behavior: male infants moved more
actively, and broke, and made contact with their mothers more frequently than did female infants. Moreover, mothers of female
infants held and groomed them more frequently and were less aggressive toward them. 相似文献
25.
K Miyamoto K Hase Y Taketani H Minami T Oka Y Nakabou H Hagihira 《Biochemical and biophysical research communications》1992,183(2):626-631
Developmental changes in glucose transporter mRNA levels in the jejunum of rats of different ages were examined by using slot blot RNA analysis. The level of SGLT1 mRNA did not change significantly through life. The GLUT5 mRNA level was highest in 10-day-old rats and then decreased reaching the adult level by day 20 after birth. The GLUT2 mRNA level was low in rats of 5 and 10 days old, but then increased progressively reaching the adult value by day 25 after birth. These results indicate that the expressions of intestinal facilitative glucose transporter genes change markedly in the third week after birth. 相似文献
26.
Takeshi Minami Masayo Ichii Yoshiyuki Tohno Setsuko Tohno Masako Utsumi Masa-oki Yamada Yuko Okazaki 《Biological trace element research》1996,55(1-2):199-205
The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries.
The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma
atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45–99-yr-old; 15 of the subjects were males and 8
were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens
where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found.
When related to age, two groups were established. Group L (45–75 yr old) and group H (>75 yr old), which exhibited aortal
Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia,
Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P)
levels (r=0.801,p<0.01) and between Al and calcium (Ca) (r=0.661,p<0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery.
In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation. 相似文献
27.
Nitrous oxide emissions from agricultural fields: Assessment, measurement and mitigation 总被引:13,自引:1,他引:12
In this paper we discuss three topics concerning N2O emissions from agricultural systems. First, we present an appraisal of N2O emissions from agricultural soils (Assessment). Secondly, we discuss some recent efforts to improve N2O flux estimates in agricultural fields (Measurement), and finally, we relate recent studies which use nitrification inhibitors to decrease N2O emissions from N-fertilized fields (Mitigation).To assess the global emission of N2O from agricultural soils, the total flux should represent N2O from all possible sources; native soil N, N from recent atmospheric deposition, past years fertilization, N from crop residues, N2O from subsurface aquifers below the study area, and current N fertilization. Of these N sources only synthetic fertilizer and animal manures and the area of fields cropped with legumes have sufficient global data to estimate their input for N2O production. The assessment of direct and indirect N2O emissions we present was made by multiplying the amount of fertilizer N applied to agricultural lands by 2% and the area of land cropped to legumes by 4 kg N2O-N ha-1. No regard to method of N application, type of N, crop, climate or soil was given in these calculations, because the data are not available to include these variables in large scale assessments. Improved assessments should include these variables and should be used to drive process models for field, area, region and global scales.Several N2O flux measurement techniques have been used in recent field studies which utilize small and ultralarge chambers and micrometeorological along with new analytical techniques to measure N2O fluxes. These studies reveal that it is not the measurement technique that is providing much of the uncertainty in N2O flux values found in the literature but rather the diverse combinations of physical and biological factors which control gas fluxes. A careful comparison of published literature narrows the range of observed fluxes as noted in the section on assessment. An array of careful field studies which compare a series of crops, fertilizer sources, and management techniques in controlled parallel experiments throughout the calendar year are needed to improve flux estimates and decrease uncertainty in prediction capability.There are a variety of management techniques which should conserve N and decrease the amount of N application needed to grow crops and to limit N2O emissions. Using nitrification inhibitors is an option for decreasing fertilizer N use and additionally directly mitigating N2O emissions. Case studies are presented which demonstrate the potential for using nitrification inhibitors to limit N2O emissions from agricultural soils. Inhibitors may be selected for climatic conditions and type of cropping system as well as the type of nitrogen (solid mineral N, mineral N in solution, or organic waste materials) and applied with the fertilizers. 相似文献
28.
29.
Yuriko Osakabe Kazuya Nanto Hiroko Kitamura Shinya Kawai Yuki Kondo Tomoyuki Fujii Keiji Takabe Yoshihiro Katayama Noriyuki Morohoshi 《Planta》1996,200(1):13-19
The polypeptide encoded by the partial fragment of cDNA of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), PALcDNAl (Osakabe et al., 1995, Plant Sci. 105: 217–226), isolated from Populus kitakamiensis (P. sieboldii x P. grandidentata), was expressed in Escherichia coli cells. The polypeptide was purified and an antiserum raised against it. The antiserum recognized a protein of 77 kDa on nitrocellulose blots after sodium dodecyl sulfate-poly-acrylamide gel electrophoresis of total protein and the partially purified PAL protein from P. kitakamiensis. Moreover,the antiserum recognized a protein on the blot after non-denaturing polyacrylamide gel electrophoresis of P. kitakamiensis proteins and this protein had PAL activity. Furthermore, the antibody inhibited PAL activity of extracts from stem tissues. These results showed that the antiserum against the partial PAL peptide recognized only the PAL subunits in extracts of P. kitakamiensis. Immunolocalization studies of P. kitakamiensis tissues revealed that the PAL protein was specifically localized in the xylem and the phloem fibers and no immunogold signal was found in the epidermis, the cortex, the pith, or the cambium of either stems or leaves.Abbreviations IgG
immunoglobulin G
- IPTG
isopropylthio--d-galactoside
- PAL
phenylalanine ammonia-lyase
The authors thank Dr. Kunio Hata of Nippon Paper Industries Co., Ltd. (Japan) for supplying P. kitakamiensis. This work was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (No. 07406008). 相似文献
30.