Growth,photosynthetic performance and shade adaptation of rubber (Hevea brasiliensis) grown in natural shade   总被引：3，自引：0，他引：3  

Senevirathna AM  Stirling CM  Rodrigo VH 《Tree physiology》2003,23(10):705-712

We compared growth, photosynthetic performance and shade adaptation of rubber (Hevea brasiliensis Muell. Arg.) plants growing in natural shade (33, 55 and 77% reduction in incoming radiation) to control plants growing in full sunlight. Stem diameter and plant height, measured over a 15-month period, were greatest in plants grown in full sunlight, and both parameters decreased with increasing shade. At 7 and 14 months after planting (MAP), total plant dry mass was highest in control plants and lowest in plants in 77% shade. Expansion of the fourth leaf whorl, monitored at 5-6 MAP, was slowest in plants in 77% shade and fastest in unshaded plants, which had more leaves and higher leaf areas and inter-whorl shoot lengths. In response to increasing shade, specific leaf area increased, whereas leaf weight ratio and relative growth rate decreased. Chlorophyll a/b ratio decreased with increasing shade, indicating shade-induced partitioning of chlorophyll into light-harvesting complexes. Compared to the response in unshaded plants, CO2 assimilation saturated at lower photosynthetic photon flux densities in plants in 77% shade, with a lower upper-asymptote to the light response curve. Chlorophyll fluorescence revealed no evidence of sustained photoinhibitory damage in unshaded plants. Dynamic photoinhibition decreased with increasing shade, with the greatest depression in the ratio of variable to maximal fluorescence around midday. We conclude that shade adaptation and shade-induced reductions in dynamic photoinhibition account for the enhanced early growth of rubber in light shade.  相似文献   

Growth hormone (GH) and reproduction: a review   总被引：5，自引：0，他引：5  

Florence Le Gac  Odile Blaise  Alex Fostier  Pierre-Yves Le Bail  Maurice Loir  Brigitte Mourot  Claudine Weil 《Fish physiology and biochemistry》1993,11(1-6):219-232

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.  相似文献   

Kinetics of formation and functional properties of conjugates prepared by dry-state incubation of beta-lactoglobulin/acacia gum electrostatic complexes     

Schmitt C  Bovay C  Frossard P 《Journal of agricultural and food chemistry》2005,53(23):9089-9099

The formation of conjugates between beta-lactoglobulin and acacia gum based on electrostatic complexes formed at pH 4.2 was investigated upon dry-state incubation for up to 14 days at 60 degrees C and 79% relative humidity (RH). By means of SEC-HPLC and RP-HPLC, it was shown that the beta-lactoglobulin incubated alone was able to form polymers with molecular masses higher than 200 kDa until 50% of the initial monomeric protein disappeared after 14 days. In the presence of acacia gum at initial protein to polysaccharide weight mixing ratios of 2:1 and 1:2, only 35% of the initial beta-lactoglobulin monomers disappeared after 14 days. Using RP-HPLC, an apparent reaction order of 2 was found for the disappearance of monomeric beta-lactoglobulin both in the presence or absence of acacia gum. However, the reaction rate was faster in the absence of acacia gum. SDS-PAGE electrophoresis with silver staining confirmed the formation of beta-lactoglobulin/acacia gum conjugates. The solubility curves of the incubated beta-lactoglobulin showed a minimum around pH 4-5. By contrast, the minimum of solubility of the beta-lactoglobulin/acacia gum incubated mixtures shifted to lower pH values compared to initial mixtures. The conjugates exhibited higher foam capacity than the incubated protein as well as lower equilibrium air/water surface tension. Conjugation at ratio 1:2 led to increased interfacial viscosity (300 mN s m(-1) at 0.01 Hz) compared to beta-lactoglobulin alone (100 mN s m(-1) at 0.01 Hz), but similar interfacial elasticity (30-40 mN m(-1)). The foam capacity of the conjugates was significantly higher than that of the incubated beta-lactoglobulin as well as foam expansion and drainage time, especially at pH 5.3, i.e., higher than the pH of formation of the conjugates.  相似文献   

Edible arabinoxylan-based films. 1. Effects of lipid type on water vapor permeability,film structure,and other physical characteristics     

Péroval C  Debeaufort F  Despré D  Voilley A 《Journal of agricultural and food chemistry》2002,50(14):3977-3983

Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was observed in OK35-AX emulsion films. Contact angles of water comparable to those observed for LDPE films (>90 degrees ) are measured on the OK35-AX film surface. Finally, only triolein-AX emulsion films had elongation higher than films without lipid. These results suggest that OK35 enhances functional properties of AX-based films and should be retained for further research.  相似文献   

Polar bears in the Beaufort Sea: A 30-year mark-recapture case history     

S. C. Amstrup  T. L. McDonald  I. Stirling 《Journal of Agricultural, Biological & Environmental Statistics》2001,6(2):221-234

Knowledge of population size and trend is necessary to manage anthropogenic risks to polar bears (Ursus maritimus). Despite capturing over 1,025 females between 1967 and 1998, previously calculated estimates of the size of the southern Beaufort Sea (SBS) population have been unreliable. We improved estimates of numbers of polar bears by modeling heterogeneity in capture probability with covariates. Important covariates referred to the year of the study, age of the bear, capture effort, and geographic location. Our choice of best approximating model was based on the inverse relationship between variance in parameter estimates and likelihood of the fit and suggested a growth from ≈ 500 to over 1,000 females during this study. The mean coefficient of variation on estimates for the last decade of the study was 0.16—the smallest yet derived. A similar model selection approach is recommended for other projects where a best model is not identified by likelihood criteria alone.  相似文献   

Release of nucleotides and nucleosides during yeast autolysis: kinetics and potential impact on flavor     

Charpentier C  Aussenac J  Charpentier M  Prome JC  Duteurtre B  Feuillat M 《Journal of agricultural and food chemistry》2005,53(8):3000-3007

  相似文献   

Cell wall polysaccharides from chalkumra (Benincasa hispida) fruit. Part I. Isolation and characterization of pectins     

Mazumder S  Morvan C  Thakur S  Ray B 《Journal of agricultural and food chemistry》2004,52(11):3556-3562

Pectic polysaccharides were obtained from chalkumra (Benincasa hispida) fruit by sequential extraction with ammonium oxalate (fraction BOX), dilute acid (fraction BHCl), and cold dilute alkali (fraction BOH). The highest yield of polysaccharides was obtained with oxalate and HCl. BOX was enriched in partly methyl-esterified galacturonic acid, whereas BHCl and BOH contained mostly galactose. All of the extracts showed similar elution patterns in size exclusion chromatography although the intrinsic viscosities (eta) were different (132 +/- 6, 100 +/- 5, and 285 + 10 mL/g for BOX, BHCl, and BOH, respectively). From fractionation by anion exchange chromatography, homogalacturonan (as seen from sugar analysis and Fourier transform infrared spectrum) accounted for more than half of BOX and 11% of BHCl. Methylation analyses and hydrolysis of BHCl with endo-beta-(1-->4)-d-galactanase showed the presence of beta-(1-->4)-d-galactan. The neutral galactan represented more than 76% of BHCl and approximately 40% of BOH. The other polysaccharides were complex galactans in BOH and an acidic arabinan (<1%) in BOX and BHCl.  相似文献   

Effect of breed and gender on bovine liver cytochrome P450 3A (CYP3A) expression and inter-species comparison with other domestic ruminants     

Dacasto M  Eeckhoutte C  Capolongoa F  Dupuy J  Carletti M  Calléja C  Nebbia C  Alvinerie M  Galtier P 《Veterinary research》2005,36(2):179-190

The cytochrome P450 (P450) superfamily represents a group of relevant enzymes in the field of drug metabolism and several exogenous or constitutional factors contribute to regulate its expression. Cattle represent an important source of animal-derived food-products and studies concerning the P450 expression are needed for the extrapolation of pharmacotoxicological data from one species to another and for the evaluation of the consumer's risk associated with the consumption of harmful residues found in foodstuffs. In the present study, possible breed-, gender- and species-differences in P4503A (the P450 subfamily more expressed in the human liver) expression were studied in vitro in Piedmontese (PDM) and Limousin (LIM) meat cattle breeds of both sexes and in domestic Ruminants (cattle, sheep and goats). Cytochrome P450 and P4503A contents as well as CYP3A-dependent drug metabolising enzymes (DME) were measured in liver microsomes. Significant lower levels of P450 (P < 0.001) and P4503A (P < 0.05) contents were observed in PDM vs. LIM of both sexes; the P4503A-dependent DME activities were significantly (P values ranging from 0.05 up to 0.001) higher in PDM cattle, particularly in males. A gender-effect in DME activities was noticed (P < 0.05) only in PDM male cattle. With regards to the species, the expression of both P4503A apoprotein and some of the related DME activities were more pronounced in sheep (P < 0.01 vs. cattle) and in goats (P < 0.05 vs. sheep; P < 0.01 vs. cattle) than in cattle. The significant differences in P4503A expression observed in LIM and PDM cattle are consistent with previously published data on strain- and breed-differences pointed out in rats and men. As far as a possible sex-effect is concerned, no clear-cut evidence is likely to be drawn. Finally, P4503A expression was more relevant in small ruminants.  相似文献   

Establishment of an in vitro plant regeneration protocol for Casuarina cunninghamiana Miq. via indirect organogenesis     

Qingbin Jiang  Yong Zhang  Chonglu Zhong  Bingshan Zeng  Didier Bogusz  Claudine Franche 《New Forests》2012,43(2):143-154

An in vitro plant regeneration protocol via indirect organogenesis from morphogenetic callus was established for Casuarina cunninghamiana Miq. Effects of plant growth regulator NAA (naphthaleneacetic acid) and BAP (6-benzylaminopurine), sucrose and AgNO₃ on callus induction, adventitious bud differentiation and shoot development were examined. Explants used were epicotyl fragments from 45-day-old seedlings. The largest callus (4.29 mm in diameter) was obtained after 1 month on a basic culture medium consisting of Murashige and Skoog ? macro- and full strength micro- elements, Nitsch and Nitsch vitamins, supplemented with 0.54 μM NAA, 3.30 μM BAP, and 30 g L⁻¹ sucrose. The calli were subcultured in the same medium above for 2 months. They were then cultured for another 2 months for adventitious bud differentiation and shoot development. The highest mean adventitious bud differentiation, number of shoots formed per callus and number of shoots ≥2 cm long per callus (47.50%, 27.38 and 4.75, respectively) were achieved on the above medium modified with NAA at 0.27 μM and supplemented with AgNO₃ 1 mg L⁻¹. Shoots were successfully rooted without plant growth regulator and the rooted plantlets survived and grew normally. This protocol for in vitro plant regeneration provides a tool not only for vegetative propagation but also for plant genetic transformation and gene function studies of C. cunninghamiana.  相似文献   

Congenital branchial apparatus malformation in a Haflinger colt     

David F  Savard C  Drolet R  Alexander K  Pang DS  Laverty S 《Veterinary surgery : VS》2008,37(1):3-11

Objective— To report the diagnosis and treatment of a branchial apparatus anomaly (BAA) associated with a mandibular malformation in a foal.
Design— Clinical report.
Animal— Haflinger foal.
Methods— A 6-day-old foal had a fluctuating cystic mass in the pharyngeal (throatlatch) region, which changed in appearance after ingestion of milk. Upper airway endoscopy and diagnostic imaging (ultrasonography, radiography, computed tomography) permitted identification of the anatomic location of a communicating tract between the lumen of the cystic mass and the pharynx. The mass was surgically removed and communication with the pharynx ligated. Histologic appearance of this mass was consistent with a branchial cyst or sinus. The mandibular malformation was managed conservatively.
Results— Surgical resection of a third branchial sinus resulted in an excellent functional and cosmetic outcome. There was no evidence of any mandibular deformity 2 years later.
Conclusion— BAA may induce secondary mandibular deformation in utero and may cause respiratory compromise postpartum. Careful surgical dissection and removal of BAA resulted in an excellent outcome.
Clinical Relevance— BAAs should be included in the differential diagnosis of a throatlatch region mass in equine neonates. Complete surgical excision is recommended and full recovery of any associated mandibular deformity may be anticipated without additional treatment in very young patients.  相似文献