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1.
Compression wood (CW) contains higher quantities of β-1-4-galactan than does normal wood (NW). However, the physiological
roles and ultrastructural distribution of β-1-4-galactan during CW formation are still not well understood. The present work
investigated deposition of β-1-4-galactan in differentiating tracheids of Cryptomeria japonica during CW formation using an immunological probe (LM5) combined with immunomicroscopy. Our immunolabeling studies clearly
showed that differences in the distribution of β-1-4-galactan between NW (and opposite wood, OW) and CW are initiated during
the formation of the S1 layer. At this stage, CW was strongly labeled in the S1 layer, whereas no label was observed in the S1 layer of NW and OW. Immunogold labeling showed that β-1-4-galactan in the S1 layer of CW tracheids significantly decreased during the formation of the S2 layer. Most β-1-4-galactan labeling was present in the outer S2 region in mature CW tracheids, and was absent in the inner S2 layer that contained helical cavities in the cell wall. In addition, delignified CW tracheids showed significantly more labeling
of β-1-4-galactan in the secondary cell wall, suggesting that lignin is likely to mask β-1-4-galactan epitopes. The study
clearly showed that β-1-4-galactan in CW was mainly deposited in the outer portion of the secondary cell wall, indicating
that its distribution may be spatially consistent with lignin distribution in CW tracheids of Cryptomeria japonica. 相似文献
2.
Bacteriophages (or phages) play major roles in the evolution of bacterial pathogens via horizontal gene transfer. Multiple phages are often integrated in a host chromosome as prophages, not only carrying various novel virulence-related genetic determinants into host bacteria but also providing various possibilities for prophage-prophage interactions in bacterial cells. In particular, Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains have acquired more than 10 prophages (up to 21 prophages), many of which encode type III secretion system (T3SS) effector gene clusters. In these strains, some prophages are present at a single locus in tandem, which is usually interpreted as the integration of phages that use the same attachment (att) sequence. Here, we present phages integrating into T3SS effector gene cluster-associated loci in prophages, which are widely distributed in STEC and EPEC. Some of the phages integrated into prophages are Stx-encoding phages (Stx phages) and have induced the duplication of Stx phages in a single cell. The identified attB sequences in prophage genomes are apparently derived from host chromosomes. In addition, two or three different attB sequences are present in some prophages, which results in the generation of prophage clusters in various complex configurations. These phages integrating into prophages represent a medically and biologically important type of inter-phage interaction that promotes the accumulation of T3SS effector genes in STEC and EPEC, the duplication of Stx phages in STEC, and the conversion of EPEC to STEC and that may be distributed in other types of E. coli strains as well as other prophage-rich bacterial species. 相似文献
3.
To detect mutagenic effects of trichloroethylene (TCE) on humans, sister-chromatid exchanges (SCEs) were analyzed in lymphocytes of 22 workers occupationally exposed to TCE and 22 matched controls. Although urinalysis in the workers revealed their obvious exposure to TCE, no increase in SCE frequencies was found in lymphocytes of the workers. SCE analysis in lymphocytes could not detect mutagenic effects by occupational exposure to TCE on humans. 相似文献
4.
Keiji Sugimoto Sachiko Fujii Masayoshi Kaiho Itsuo Nakamura 《Cell and tissue research》1990,261(3):509-516
Summary Actin-containing cytoplasmic fibers were visualized in the mesenteric mesothelial cells of the large intestine of bullfrog tadpoles by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers were concurrently stained by immunofluorescence using antibodies to myosin or -actinin. Electron microscopy showed the presence of bundles of microfilaments in the basal cytoplasm of the cells. Such fibers in the mesothelial cells may be comparable to the stress fibers present in cultured cells. The mesothelial cells initially formed axially oriented stress fibers when they changed from a rhombic to a slender spindle-like shape. On the other hand, stress fibers disappeared as cells transformed from elongated to polygonal shapes during the period of metamorphic climax. Expression of stress fibers in these cells appears to be related to the degree of tension loaded on the mesentery, which may be generated by mesenteric winding. These stress fibers in the mesothelial cells may serve to regulate cellular transformation. They may also help to maintain cellular integrity by strengthening the cellular attachment to subepithelial tissue against tensile stress exerted on the mesentery. 相似文献
5.
Summary Two laboratory experiments were conducted to examine the ovipositional preferences of the egg parasitoidOoencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) for parasitized and unparasitizedMegacopta punctatissimum Montandon (Hemiptera: Plataspidae). Females that had never oviposited or that had not oviposite for 3 days preferred recently parasitized hosts more than unparasitized hosts. The preference for recently parasitized hosts appeared to be mediated by the punctures in already parasitized hosts made by the ovipositor of the first female. Survival of the parasitoid progeny was lower in recently parasitized hosts than in unparasitized hosts. However, handling time of parasitized hosts was extremely short relative to that of unparasitized hosts, because the superparasitizing female could use the punctures made by the previous females. It is concluded that the females preferred the parasitized hosts over unparasitized hosts because the benefit of saving time and energy for drilling was more than the cost of progeny survival. 相似文献
6.
Sada E Katoh S Terashima M Yamana S Ueyama N Nagaya M 《Biotechnology and bioengineering》1986,28(1):1-6
Permeabilities of several solutes through the composite membranes containing phospholipids have been measured. They were inversely proportional to the content of the phospholipids in the membrane. Both the permeability of solutes and the degree of permeability change around the phase transition temperature of the phospholipids for the hydrophobic solutes such as n-butanol and salicylamide were larger than those for the hydrophilic solutes such as amino acids and pyridoxine. These results suggest thatthe permeation path of hydrophobic solutes is different from that of hydrophilic ones. The addition of phosphatidyl ethanolamine, phosphatidyl serine, or phosphatidic acid to the composite membrane influenced the solute permeability due to the introduced negative charge and/or the change in the molecular packing of phospholipid. 相似文献
7.
Keiji Kanamitsu 《Population Ecology》1965,7(1):16-22
A field population of Evetria cristata was studied in 10 plots in 1962 and in 6 plots in 1963. These plots were divided into 2 or 3 groups of different population levels of the shoot moth in respective years. The survival of the insect was then analysed in these different groups of plots. The survival rate of E. cristata from eggs to adults in the first generation was found always higher in the group with low population density, which indicates the existence of some factors that affect the population more severely when the insect is more abundant. Lissonota evetriae and Pediobius sp. seemed to have killed more proportion of the hosts where the shoot moth density was high. However, the total effect of the all natural enemies was not always great in the plots with high density of the moth. The survival of the second generation of the moth in 1963 was observed to be much higher at any population level than in the other generations. 相似文献
8.
Kenji Takeuchi Sayumi Shibamoto Makio Hayakawa Takamitsu Hori Keiji Miyazawa Naomi Kitamura Fumiaki Ito 《Experimental cell research》1996,223(2):420
Hepatocyte growth factor (HGF) stimulated cell migration of human gastric carcinoma cell lines MKN1, MKN7, and MKN28. Epidermal growth factor (EGF) also stimulated the cell migration of these three cell lines. In MKN7 cells, HGF-stimulated cell migration was rather reduced in the presence of EGF, whereas such an observation was not made with MKN1 and MKN28 cells. Therefore, we compared the effect of EGF on HGF-stimulated HGF receptor phosphorylation in these cell lines. HGF induced a rapid tyrosine phosphorylation of the HGF receptor in all these cell lines. In MKN7 cells, the increased phosphorylation was further enhanced by EGF, although EGF alone did not affect tyrosine phosphorylation of the HGF receptor. In MKN1 and MKN28 cells, EGF did not influence tyrosine phosphorylation of the HGF receptor, whether HGF was present or not. The data presented here suggest that EGF negatively modulates the cellular response to HGF by increasing tyrosine phosphorylation of the HGF receptor in certain types of epithelial cells, e.g., MKN7 cells. 相似文献
9.
Prosaposin Facilitates Sciatic Nerve Regeneration In Vivo 总被引:3,自引:0,他引:3
Yasunori Kotani Seiji Matsuda Masahiro Sakanaka Keiji Kondoh Shu-ichi Ueno Akira Sano 《Journal of neurochemistry》1996,66(5):2019-2025
Abstract: Prosaposin, a multifunctional protein, is the precursor of saposins, which activate sphingolipid hydrolases. In addition to acting as a precursor for saposins, prosaposin has been shown to rescue hippocampal CA1 neurons from lethal ischemic damage in vivo and to promote neurite extension of neuroblastoma cells in vitro. Here we show that prosaposin, when added to a collagen-filled nerve guide after sciatic nerve transection in guinea pigs, increased dramatically the number of regenerating nerve fibers within the guide. To identify the target neurons of prosaposin during peripheral nerve regeneration, we determined the degree of atrophy and chromatolysis of neurons in the spinal anterior horn and dorsal root ganglia on the prosaposin-treated and untreated side. The effect of prosaposin on large spinal neurons and small neurons of the dorsal root ganglion was more conspicuous. Subsequent immunohistochemistry demonstrated that the atrophy of cholinergic large neurons in the anterior horn is prevented to significant extent by prosaposin treatment. These findings suggest that prosaposin promotes peripheral nerve regeneration by acting on α-motor neurons in the anterior horn and on small sensory neurons in the dorsal root ganglion. The present study raises the possibility of using prosaposin as a tool for the treatment of peripheral nerve injuries. 相似文献
10.
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