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861.
862.
Evergreen broadleaved forests (EBLF), the zonal forest ecosystem of the subtropical zone in east China, have been degraded
from recent anthropogenic disturbance. Understanding the role of past disturbances in EBLFs would be helpful to the restoration
of degraded EBLFs. We used dendroecological techniques to reconstruct the disturbance history of a secondary EBLF dominated
by Schima superba and Castanopsis carlesii in Tiantong National Forest Park (29°48′N, 121°47′E), Zhejiang Province, East China. The disturbances were inferred from
tree-ring growth release and long-term establishment patterns obtained from 91 overstory trees. The initial growth rates of
these trees were compared to trees originating in the understory to evaluate the intensity of past disturbances. The spatial
distribution patterns of disturbances were portrayed with tree mapping. The results revealed that there were five disturbances,
averaging one disturbance per decade over the past half century. The first disturbance event was probably most intense given
that most canopy trees established at that time and displayed high initial growth rates. The timing of the second disturbance
event coincided with the documented selective logging. The last three disturbances, having lower tree growth responses and
a clumped spatial distribution of gap creation, were probably the result of recurring typhoons. The first two disturbances
led to tree regeneration and secondary succession, represented mainly by long-lived deciduous trees in the forest. The subsequent
disturbances facilitated the stand development process, creating a complex three-dimensional structure from a pre-existing
single-age cohort. This study suggests that EBLFs affected by large disturbances can recover in a few decades and the frequent
gap disturbances probably facilitate its process in the early successional stages. 相似文献
863.
Evidence for 1-(Malonylamino)cyclopropane-1-Carboxylic Acid Being
the Major Conjugate of Aminocyclopropane-1-Carboxylic Acid in Tomato
Fruit 总被引:1,自引:0,他引:1 下载免费PDF全文
Tomato (Lycopersicon esculentum Miller) fruit discs fed with [2,3-14C]1-aminocyclopropane-1-carboxylic acid (ACC) formed 1-malonyl-ACC (MACC) as the major conjugate of ACC in fruit throughout all ripening stages, from immature-green through the red-ripe stage. Another conjugate of ACC, γ-glutamyl-ACC (GACC), was formed only in mature-green fruit in an amount about 10% of that of MACC; conjugation of ACC into GACC was not detected in fruits at other ripening stages. No GACC formation was observed from etiolated mung bean (Vigna radiata [L.] Wilczek) hypocotyls, etiolated common vetch (Vicia sativum L.) epicotyls, or pea (Pisum sativum L.) root tips, etiolated epicotyls, and green stem tissue, where active conversion of ACC into MACC was observed. GACC was, however, formed in vitro in extracts from fruit of all ripening stages. GACC formation in an extract from red fruit at pH 7.15 was only about 3% of that at pH 8.0, the pH at which most assays were run. Our present in vivo data support the previous contention that MACC is the major conjugate of ACC in plant tissues, whereas GACC is a minor, if any, conjugate of ACC. Thus, our data do not support the proposal that GACC formation could be more important than MACC formation in tomato fruit. 相似文献
864.
Yanchun Liang Wei Wang Jiaming Huang Hao Tan Tianyu Liu Chunliang Shang Duo Liu Luyan Guo Shuzhong Yao 《PloS one》2015,10(12)
Previous studies have demonstrated the involvement of nerve repellent factors in regulation of the imbalanced innervation of endometriosis. This prospective study aims to explore the role of Sema 3A in regulating aberrant sympathetic innervation in peritoneal and deep infiltrating endometriosis. Ectopic endometriotic lesion were collected from patients with peritoneal endometriosis (n = 24) and deep infiltrating endometriosis of uterosacral ligament (n = 20) undergoing surgery for endometriosis. Eutopic endometrial samples were collected from patients with endometriosis (n = 22) or without endometriosis (n = 26). Healthy peritoneum (n = 13) from the lateral pelvic wall and healthy uterosacral ligament (n = 13) were obtained from patients who had no surgical and histological proof of endometriosis during hysterectomy for uterine fibroids. Firstly, we studied the immunostaining of Sema 3A, Plexin A1 and NRP-1 in all the tissues described above. Then we studied the nerve fiber density (NFD) of endometriosis-associated (sympathetic) nerve and para-endometriotic (sympathetic) nerve by double immunofluorescence staining. Finally we analyzed the relationship between expression of Sema 3A in stromal cells of endometriotic lesion and the aberrant innervation of endometriosis. Semi-quantitative immunostaining demonstrated that (1) Higher immunostaining of Sema 3A were found in the eutopic endometrial glandular epithelial cells from patients with endometriosis (p = 0.041) than those without endometriosis; (2) Sema 3A immunostaining was higher in glandular epithelial cells of peritoneal endometriosis (P<0.001) and deep infiltrating endometriotic lesions of uterosacral ligament (P = 0.028)compared with glandular epithelial cells of the endometrium from women with endometriosis, while its expression in ectopic stormal cells in both groups were significantly lower than that from eutopic endometrium of women without endometirosis (P<0.001, P<0.001, respectively). NFDs of Anti-TH (+) endometriosis-associated sympathetic nerve of peritoneal endometriosis (p<0.001) and deep endometriosis of uterosacral ligament (p<0.001) were significantly lower than NFDs of para-endometriotic sympathetic nerve. Our results suggest that Sema 3A may contribute to the regulation of aberrant sympathetic innervation in peritoneal and deep infiltrating endometriosis. 相似文献
865.
To determine the feasibility of inducing mutation for Gibberella moniliformis EZG0807 with a superconducting magnet, this paper investigated the effects of this instrument on the filamentous fungus G. moniliformis EZG0807. The superconducting magnet could simulate space gravity environment from hypo-gravity (0 g) to hyper-gravity (2 g).
After G. moniliformis EZG0807 was exposed to the superconducting magnet for 72 h, the morphological observation, agar diffusion method, and amplified
fragment length polymorphism were performed to detect the mutagenic effects in the aspect of morphology, the activity of metabolites,
and genomic DNA, respectively. The mutant strain M7212 in 1 g (16 T) was different from the control in the morphology, showing
no activity against the four tested bacteria Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Proteus vulgaris, and lost a size of 675 bp band on the genomic DNA. These results indicated that the superconducting magnet could be used
to induce mutation for G. moniliformis EZG0807, which enabled improving the production of G. moniliformis EZG0807 and providing an effective approach for fungal breeding. 相似文献
866.
Shouguo Shi Fengwang Ma Yonghong Li Fengjuan Feng Zengzhen Shang 《In vitro cellular & developmental biology. Plant》2012,48(1):1-6
In China, the native Lanzhou lily (Lilium davidii var. unicolor) is used as an edible lily and is an important source of ascorbic acid. However, an efficient transformation system has not
been developed for this important crop. Here, we describe the first successful genetic transformation mediated by particle
bombardment in this lily variety. We used pCAMBIA-GLDH, which contains the l
-galactono-1, 4-lactone dehydrogenase gene from apple, a hygromycin phosphotransferase gene as a selectable marker, and an intron-containing β-glucuronidase gene
as a reporter. In all, 35 transgenic lines were selected via GUS assays and PCR; from these, eight were confirmed by Southern
analyses. Transgenic plants were transferred to soil and grown under greenhouse conditions. The levels of reduced ascorbate
and total ascorbate (reduced ascorbate + oxidized ascorbate) in transgenic plants were found to be two to seven times those
in non-transgenic controls. 相似文献
867.
Porcine reproductive and respiratory syndrome is caused by the PRRS virus (PRRSV),which has six structural proteins (GP2,GP3,GP4,GP5,M and N). GP5 and N protein are important targets for serological detection by enzyme-linked immunosorbent assay (ELISA) and other methods. Toward this goal,we developed an indirect ELISA with recombinant GP5 antigens and this method was validated by comparison to the LSI PRRSV-Ab ELISA kit. The results indicated that the optimal concentration of coated recombinant antigen was... 相似文献
868.
869.
Overexpression of genes of the cell wall stimulon in clinical isolates of Staphylococcus aureus exhibiting vancomycin-intermediate- S. aureus-type resistance to vancomycin 下载免费PDF全文
McAleese F Wu SW Sieradzki K Dunman P Murphy E Projan S Tomasz A 《Journal of bacteriology》2006,188(3):1120-1133
Custom-designed gene chips (Affymetrix) were used to determine genetic relatedness and gene expression profiles in Staphylococcus aureus isolates with increasing MICs of vancomycin that were recovered over a period of several weeks from the blood and heart valve of a patient undergoing extensive vancomycin therapy. The isolates were found to be isogenic as determined by the GeneChip based genotyping approach and thus represented a unique opportunity to study changes in gene expression that may contribute to the vancomycin resistance phenotype. No differences in gene expression were detected between the parent strain, JH1, and JH15, isolated from the nares of a patient contact. Few expression changes were observed between blood and heart valve isolates with identical vancomycin MICs. A large number of genes had altered expression in the late stage JH9 isolate (MIC = 8 microg/ml) compared to JH1 (MIC = 1 microg/ml). Most genes with altered expression were involved in housekeeping functions or cell wall biosynthesis and regulation. The sortase-encoding genes, srtA and srtB, as well as several surface protein-encoding genes were downregulated in JH9. Two hypothetical protein-encoding genes, SAS016 and SA2343, were dramatically overexpressed in JH9. Interestingly, 27 of the genes with altered expression in JH9 grown in drug-free medium were found to be also overexpressed when the parental strain JH1 was briefly exposed to inhibitory concentrations of vancomycin, and more than half (17 of 27) of the genes with altered expression belonged to determinants that were proposed to form part of a general cell wall stress stimulon (S. Utaida et al., Microbiology 149:2719-2732, 2003). 相似文献
870.
The diversity and content of available nitrogen sources in the growth medium both are very important in the accumulation of ergosterol in the yeast cell membrane. Growth on the good nitrogen sources such as ammonia can harvest more yeast cells than on poor ones, but ergosterol content in those yeast cells is relatively lower. Ergosterol content, one of the most variable parameters in ergosterol production by yeast cultivation, is greatly influenced by nitrogen limitation. The aim of our work was to study how the nitrogen sources affected the membrane ergosterol content and increase the total ergosterol yield. On the premise of keeping high ergosterol content in yeast cell, the ergosterol yield was enhanced by increasing the yeast biomass. Direct feed back control of glucose using an on-line ethanol concentration monitor was introduced to achieve high cell density. Ammonia, which acted as nitrogen source, was added to adjust pH during fermentation process, but its addition needed careful control. Cultivation in 5 L bioreactor was carried out under following conditions: culture temperature 30+/-1 degrees C, pH 5.5+/-0.1, agitation speed 600 rpm, controlling ethanol concentration below 1% and controlling ammonium ion concentration below 0.1 mol/L. Under these conditions the yeast dry weight reached 95.0+/-2.6 g/L and the ergosterol yield reached 1981+/-34 mg/L. 相似文献