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排序方式: 共有458条查询结果,搜索用时 26 毫秒
11.
Serean L Adams John F Smith Rodney D Roberts Achim R Janke Nick G King Harry Robin Tervit Stephen C Webb 《Aquaculture Research》2008,39(13):1434-1442
The robustness of Pacific oyster, Crassostrea gigas (Thunberg), sperm cryopreservation in the context of selective breeding based on family lines was investigated. Irrespective of egg density, high fertilization success was achieved with cryopreserved sperm when sperm:egg ratios of 1000:1 to 10 000:1 were used. Variation among replicate runs on the same oyster batches was minimal, indicating that cryopreservation and larval rearing procedures were repeatable. Twenty independent single male–female crosses were made to assess the utility of cryopreserved sperm in selective breeding. The fertility of unfrozen sperm was generally a poor predictor of cryopreserved sperm fertility. Based on D‐larval yields, 17 of the 20 crosses were likely to yield adequate spat for selective breeding (>105 D‐larvae from 1 million eggs), two were marginal (5 × 104 D‐larvae) and one was inadequate (4 × 103 D‐larvae). An alternative fertilization strategy to improve D‐yield from a given number of sperm was then tested. Fertilizing 10 million eggs at a sperm:egg ratio of 200:1 increased the total D‐yield when compared with fertilizing 1 million eggs at a sperm:egg ratio of 2000:1 for the same male–female pair. We conclude that, despite wide variation in fertility, cryopreserved sperm is useful for family production. 相似文献
12.
A protocol is described for the in vitro propagation of Abies amabilis (Dougl.) Forbes. Over 60% of the cotyledonary explants from 5-day-old cotyledons formed shoots when cultured for 7 days on Schenk and Hildebrandt's (SH) medium containing 10 micro M N(6)-benzyladenine (BA) followed by another 7 days on SH medium containing 10 micro M each of BA and zeatin. Shoot multiplication was unsuccessful. Seventeen percent rooting was obtained after pulsing for 4 h in 1 mM indole-3-butyric acid and planting pulsed shoots in 1/1 (v/v) perlite/vermiculite. Cell clusters (promeristemoids) of five to seven cells were observed on the cotyledonary explants after 7 days of culture in the presence of cytokinin. These cells developed further into meristematic domes and apical meristems. In the absence of cytokinin, stomata and resin canals reached maturity, whereas cells within the cortex became vacuolated and developed into palisade and spongy mesophyll. 相似文献
13.
A protocol is described for the in vitro production of plantlets from embryonic explants of eastern white cedar (Thuja occidentalis L.). Bud induction was optimal when embryonic explants were cultured for 20-25 days on half-strength Quoirin and Le Poivre mineral salts containing equimolar concentrations (10(-6) M) of N(6)-benzyladenine and 2-isopentyl adenine. Bud development was achieved in phytohormone-free medium in the presence of activated charcoal. Maximal shoot elongation occurred on half-strength Quoirin and Le Poivre salts, whereas shoot multiplication was optimal on half-strength Bornman's MCM salts in the presence of cytokinin. Hardened shoots, dipped in commercial rooting powder containing indole-3-butyric acid, rooted optimally in mist under non-sterile greenhouse conditions. Both rooting and subsequent plantlet growth was best when Redi-Earth((R)) was used as a substrate. Over 250 plantlets per embryo can be produced annually by this technique. 相似文献
14.
The gulf between process-based and empirical approaches to modeling tree growth may be bridged, in part, by the use of a common model. To this end, we have formulated a process-based model of tree growth that can be fitted and applied in an empirical mode. The growth model is grounded in pipe model theory and an optimal control model of crown development. Together, the pipe model and the optimal control model provide a framework for expressing the components of tree biomass in terms of three standard inventory variables: tree height, crown height and stem cross-sectional area. Growth rates of the inventory variables and the components of biomass are formulated from a carbon balance. Fundamentally, the parameters of the model comprise physiological rates and morphological ratios. In principle, the values of these parameters may be estimated by lower-level process models. Alternatively, the physiological and morphological parameters combine, under reasonable assumptions, into a set of aggregate parameters, whose values can be estimated from inventory data with a statistical fitting procedure. 相似文献
15.
Harry X. Wu Mike B. Powell Junli L. Yang Milo Ivković Tony A. McRae 《Annals of Forest Science》2007,64(1):1-9
A total of 360 bark-to-bark-through-pith wood strips were sampled at breast height from 180 trees in 30 open-pollinated families from two rotation-aged genetic trials to study inheritance, age-age genetic correlation, and early selection efficiency for wood quality traits in radiata pine. Wood strips were evaluated by SilviScan® and annual pattern and genetic parameters for growth, wood density, microfibril angle (MFA), and stiffness (modulus of elasticity: MOE) for early to rotation ages were estimated. Annual ring growth was the largest between ages 2–5 years from pith, and decreased linearly to ages 9–10. Annual growth was similar and consistent at later ages. Wood density was the lowest near the pith, increased steadily to age 11–15 years, then was relatively stable after these ages. MFA was highest (35°) near the pith and reduced to about 10° at age 10–15 years. MFA was almost unchanged at later ages. MOE increased from about 2.5 GPa near the pith to about 20 GPa at ages 11–15 years. MOE was relatively unchanged at later ages. Wood density and MOE were inversely related to MFA. Heritability increased from zero near the pith and stabilised at ages 4 or 5 for all four growth and wood quality traits (DBH, density, MFA and MOE). Across age classes, heritability was the highest for area-weighted density and MFA, lowest for DBH, and intermediate for MOE. Age-age genetic correlations were high for the four traits studied. The genetic correlation reached 0.8 after age 7 for most traits. Early selection for density, MFA and MOE were very effective. Selection at age 7–8 has similar effectiveness as selection conducted at rotation age for MFA and MOE and at least 80% effective for wood density. 相似文献
16.
Green tea polyphenol extract regulates the expression of genes involved in glucose uptake and insulin signaling in rats fed a high fructose diet 总被引:1,自引:0,他引:1
Cao H Hininger-Favier I Kelly MA Benaraba R Dawson HD Coves S Roussel AM Anderson RA 《Journal of agricultural and food chemistry》2007,55(15):6372-6378
Green tea has antidiabetic, antiobesity, and anti-inflammatory activities in animal models, but the molecular mechanisms of these effects have not been fully understood. Quantitative real-time polymerase chain reaction (PCR) was used to investigate the relative expression levels and the effects of green tea (1 and 2 g solid extract/kg diet) on the expression of glucose transporter family genes (Glut1/Slc2a1, Glut2/Slc2a2, Glut3/Slc2a3, and Glut4/Slc2a4) and insulin signaling pathway genes (Ins1, Ins2, Insr, Irs1, Irs2, Akt1, Grb2, Igf1, Igf2, Igf1r, Igf2r, Gsk3b, Gys1, Pik3cb, Pik3r1, Shc1, and Sos1) in liver and muscle of rats fed a high-fructose diet known to induce insulin resistance and oxidative stress. Glut2 and Glut4 were the major Glut mRNAs in rat liver and muscle, respectively. Green tea extract (1 g) increased Glut1, Glut4, Gsk3b, and Irs2 mRNA levels by 110, 160, 30, and 60% in the liver, respectively, and increased Irs1 by 80% in the muscle. Green tea extract (2 g) increased Glut4, Gsk3b, and Pik3cb mRNA levels by 90, 30, and 30% but decreased Shc1 by 60% in the liver and increased Glut2, Glut4, Shc1, and Sos1 by 80, 40, 60, and 50% in the muscle. This study shows that green tea extract at 1 or 2 g/kg diet regulates gene expression in the glucose uptake and insulin signaling pathway in rats fed a fructose-rich diet. 相似文献
17.
The objective of this work was to identify the dominant aggregating peptides from a whey protein hydrolysate (degree of hydrolysis of 6.8%) obtained with Bacillus licheniformis protease. The aggregating peptides were fractionated with preparative reversed-phase chromatography and identified with liquid chromatography-mass spectrometry. The results showed that the dominant aggregating peptide, at pH 7.0, was beta-lg AB [f1-45]. In addition, the peptides beta-lg AB [f90-108]-S-S-alpha-la [f50-113], alpha-la [f12-49]-S-S-alpha-la [f50-113], beta-lg AB [f90-108]-S-S-beta-lg AB [f90-108], beta-lg A [f90-157], and beta-lg AB [f135-157/158] were also identified as main aggregating peptides. The results further showed that aggregation, via hydrophobic interactions, prevented further digestion (at pH 8.0), thereby explaining the large size of the aggregating peptides. It is hypothesized that B. licheniformis protease breaks down hydrophilic segments in the substrate and, therefore, preserves hydrophobic segments that aggregate once exposed to the solvent. 相似文献
18.
van Boxtel EL van den Broek LA Koppelman SJ Vincken JP Gruppen H 《Journal of agricultural and food chemistry》2007,55(21):8772-8778
Mildly extracted peanut allergen Ara h 1 was previously reported to occur as an oligomeric complex. In this paper we describe how the protein in this oligomeric complex interacts noncovalently with phenolic compounds of the proanthocyanidin type. These interactions are being disrupted during anion exchange chromatography, resulting in the dissociation of the oligomeric Ara h 1 complex into protein trimers. By use of the known three-dimensional structure of beta-conglycinin, a soy protein homologous to Ara h 1, proline-rich regions were observed in silico on both faces of its trimeric structure, which are conserved in Ara h 1. These proline-rich regions could explain the binding of proanthocyanidins to Ara h 1 and the formation of multiple Ara h 1 trimer complexes. This was supported by the observation that the addition of peanut proanthocyanidins to trimeric Ara h 1 and to beta-conglycinin resulted in the formation of soluble oligomeric protein complexes. The structurally related legumin proteins do not contain such proline-rich regions on both sides of the protein, and proanthocyanidins were shown to have a lower affinity for legumin proteins from peanuts and soybeans (peanut allergen Ara h 3 and soy glycinin, respectively). Ara h 1 present as the oligomeric complex is assumed to be the representative form of the allergen in which it is consumed by humans. 相似文献
19.
A new method was developed to identify regions in proteins from which peptides are derived with specific functional properties. This method is applicable for systems in which peptides of a hydrolyzed protein possess specific functional properties, but are too large to be sequenced directly and/or the peptide mixture is too complex to purify and characterize each peptide individually. In the present work, aggregating peptides obtained by proteolytic hydrolysis of soy glycinin were used as a case study. The aggregating peptides are isolated and subsequently further degraded with trypsin to result in peptides with a mass <5000 Da to enable sequence identification using RP-HPLC-MS in combination with MS/MS. Prior to RP-HPLC the peptides are fractionated using anion and cation exchange chromatography. The fractions obtained are analyzed with RP-HPLC-MS. The peptides, with identified sequences, were quantified using the peak areas of the RP-HPLC chromatograms measured at 214 nm. Next, the peak areas were corrected for the molar extinction coefficient of the individual peptides, followed by accumulative-quantitative peptide mapping. The results show that in complex systems, based on the method described, the regions in the parental protein from which the functional peptides originate can be properly identified. 相似文献
20.
Fancourt Bronwyn A. Harry Glen Speed James Gentle Matthew N. 《Journal of pest science》2022,95(1):523-524
Journal of Pest Science - 相似文献