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排序方式: 共有139条查询结果,搜索用时 342 毫秒
1.
2.
The effects of root colonization by the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck and Smith on growth, flower and fruit production, and fruit quality were studied in field-grown tomato plants exposed to varying intensities of drought stress. Inoculated (M+) and non-inoculated (M−) tomato seedlings were exposed to varying intensities of drought stress by adjusting irrigation intervals. Mycorrhizal plants had significantly higher uptake of N and P in both roots and shoots regardless of intensities of drought stress. AM inoculation also significantly increased shoot dry matter and the number of flowers and fruits. The fruit yields of M+ plants under severe, moderate, mild drought-stressed conditions were higher than M− plants by 24.7%, 23.1%, 16.2% and 12.3%, respectively. Furthermore, M+ plants produced tomato fruits that contain significantly higher quantities of ascorbic acid and total soluble solids (TSS) than M− plants. Mycorrhizal effects increased with increasing intensity of drought. The overall results suggest that mycorrhizal colonization affects host plant nutritional status, water stratus and growth under field conditions and thereby alters reproductive behaviour, fruit production and quality of fruits under both well-watered and drought-stressed conditions. 相似文献
3.
The impact of drought conditioning on the ability of eight-week-old jack pine (Pinus banksiana Lamb.) seedlings to withstand drought was assessed. Two progressive cycles of drought conditioning significantly increased the survival of seedlings subjected to a subsequent prolonged drought. The in vivo accumulation of several root membrane proteins during drought conditioning was correlated with an increase in seedling survival. A group of root proteins, ranging in molecular mass from 43 to 47 kDa, increased accumulation during one cycle of drought conditioning and to a lesser extent during two cycles of drought conditioning. The accumulation of several low molecular mass membrane and soluble proteins also increased during drought conditioning, suggesting that these proteins may play an important role in the enhancement of drought tolerance. In vitro translation studies showed a general increase in the abundance of protein products encoded by mRNAs from drought-conditioned seedlings. Although the majority of the in vitro translation products appeared in both control and drought-conditioned seedlings, one mRNA encoding a 15 kDA translated protein was more prominent during the second cycle of drought conditioning. 相似文献
4.
5.
Subramanian A Ahn J Balasubramaniam VM Rodriguez-Saona L 《Journal of agricultural and food chemistry》2007,55(22):9311-9317
Pressure-assisted thermal processing (PATP) is being widely investigated for processing low acid foods. However, its microbial safety has not been well established and the mechanism of inactivation of pathogens and spores is not well understood. Fourier transform infrared (FT-IR) spectroscopy was used to study some of the biochemical changes in bacterial spores occurring during PATP and thermal processing (TP). Spore suspensions (approximately 10(9) CFU/mL of water) of Clostridium tyrobutyricum, Bacillus sphaericus, and three strains of Bacillus amyloliquefaciens were treated by PATP (121 degrees C and 700 MPa) for 0, 10, 20, and 30 s and TP (121 degrees C) for 0, 10, 20, and 30 s. Treated and untreated spore suspensions were analyzed using FT-IR in the mid-infrared region (4000-800 cm(-1)). Multivariate classification models based on soft independent modeling of class analogy (SIMCA) were developed using second derivative-transformed spectra. The spores could be differentiated up to the strain level due to differences in their biochemical composition, especially dipicolinic acid (DPA) and secondary structure of proteins. During PATP changes in alpha-helix and beta-sheets of secondary protein were evident in the spectral regions 1655 and 1626 cm(-1), respectively. Infrared absorption bands from DPA (1281, 1378, 1440, and 1568 cm(-1)) decreased significantly during the initial stages of PATP, indicating release of DPA. During TP changes were evident in the bands associated with secondary proteins. DPA bands showed little or no change during TP. A correlation was found between the spore's Ca-DPA content and its resistance to PATP. FT-IR spectroscopy could classify different strains of bacterial spores and determine some of the changes occurring during spore inactivation by PATP and TP. Furthermore, this technique shows great promise for rapid screening PATP-resistant bacterial spores. 相似文献
6.
The effects of (ip, 10 injections over 20 days) of melatonin (75 g 100 g–1 BW), the serotonin (5-HT)-synthesis blocker, para-cholorophenylalanine (p-CPA, 10 mg 100g–1 BW) and the catecholamine-synthesis blocker, -methylparatyrosine (-MPT, 10 mg 100 g–1 BW) on gonadotropin (GTH) secretion and ovarian activity were studied in
Heteropneustes fossilis
during late preparatory to early prespawning (April–May). The treatments resulted in significant reductions of plasma GTH and estradiol-17 levels, the gonadosomatic index, frequency distribution of vitellogenic and postvitellogenic oocytes, and ovarian and serum 32p-labelled alkali-labile phosphoprotein (a marker of vitellogenic activity). Most of the oocytes were nonvitellogenic or had undergone atretic changes. The hepatic 32-phosphoprotein content increased significantly over the saline control value. The effects were similar and pronounced in the p-CPA and melatonin-treated groups but were moderate in the -MPT-treated group. Hypothalamic 5-HT content and turnover were significantly inhibited in the p-CPA and melatonin-treated groups but the content and turnover of catecholamines were not. The -MPT treatment decreased significantly the content and turnover of dopamine (DA), noradrenaline (NA), and adrenaline (A) but did not influence the 5-HT content or turnover. These results suggest that 5-HT, NA and A are stimulatory to GTH secretion and that melatonin may act on the serotonergic system to inhibit the pituitary-gonadal axis.to whom correspondence should be addressed.A part of the results was presented at the International Workshop on Pineal gland: Its molecular signals and published as an abstract in Neuroendocrinol. Lett. 14: 399 pp., 1992. 相似文献
7.
L.Y. Zhou B. Senthilkumaran D.S. Wang C.C. Sudhakumari T. Kobayashi H. Kajiura-Kobayashi M. Matsuda M. Yoshikuni Y. Nagahama 《Fish physiology and biochemistry》2003,28(1-4):381-382
A 548 bp partial cDNA fragment of 17β-hydroxysteroid dehydrogenase (17β-HSD1) was obtained by RT-PCR from the ovary of Nile Tilapia. The expression of 17β-HSD1 was high from 0 to 11 days after spawning, but there was a sharp decline at the day of spawning (day 14) indicating its involvement in ovarian cycle. 相似文献
8.
D.S. Wang B. Senthilkumaran T. Kobayashi H. Kajiura-Kobayashi M. Matsuda M. Yoshikuni Y. Nagahama 《Fish physiology and biochemistry》2003,28(1-4):225-226
Tilapia riboflavin-binding protein (RfBP) cDNA was isolated by library screening. Even though it shows only 31~35% similarity to the reported RfBPs, tilapia RfBP is conserved in amino acid residues that are known to be essential for its protein function. The exclusive expression of RfBP in the brain-pituitary-gonadal axis, as revealed by both RT-PCR and Northern blot, suggested a possible role for RfBP in fish reproduction. 相似文献
9.
Reproduction in fishes is influenced by thyroid hormones at various levels of gonadal cell differentiation and steroidogenesis.
Thyroid hormones have recently also emerged as an important modulator of season- and photoperiod-dependent variations in the
reproductive cycle with a possible effect on the hypothalamo–hypophyseal axis and pineal interactions. This review describes
the current status of thyroid hormone research in relation to reproduction, with special emphasis on contributions to this
field by Indian researchers including our laboratory. Evidence is provided for the multifocal action of thyroid hormones at
various levels of the hypothalamo–hypophyseal–gonadal axis affecting reproduction. The underlying physiological and molecular
mechanisms pertaining to thyroid hormone modulation of reproduction, such as gonadotropin-releasing hormone (GnRH) synthesis
and release, androgen and gonadotropin receptor expression, gonadotropin (GTH) expression, and tissue sensitivity to GTHs
are highlighted with relevant discussions of the current technical limitations, applications, and future perspectives of research
in this field. 相似文献
10.
T. N. Jacob J. P. Pandey K. Raghuveer G. Sreenivasulu A. D. Gupta M. Yoshikuni A. Jagota B. Senthilkumaran 《Fish physiology and biochemistry》2005,31(2-3):271-274
Effect of experimentally induced thyroxine overdose on the testis and seminal vesicles was studied in the air-breathing catfish,
Clarias gariepinus during the preparatory and the pre-spawning phase. The present study revealed a marked reduction in testosterone level in
serum, testis and seminal vesicles (SV). Histological examination showed a considerable reduction in the number of spermatozoa/spermatids
in the seminiferous tubular lumen as well as depletion of fluid in the loculi of SV. SDS-PAGE analysis of SV fluid proteins
demonstrated a significant decrease in the level of a ~27 kDa protein in thyroxine treated fishes. Evidences are presented
here to indicate that thyroid hormone plays a role in regulating testis and SV function in catfish.
T.N. Jacob and J.P. Pandey contributed equally 相似文献