Background Infancy is a critical period of growth and physiological development,in which breast milk is the best source of nutrients.Compared to western countries,research on breast milk of Chinese population are limi...Background Infancy is a critical period of growth and physiological development,in which breast milk is the best source of nutrients.Compared to western countries,research on breast milk of Chinese population are limited.Thus,it is necessary to measure breast milk energy and macronutrient concentrations of healthy urban Chinese mothers at different lactation stages,to expand the database of milk composition of Chinese population,and to examine whether dietary or other maternal factors can affect the levels of macronutrients in breast milk.Methods Breast milk of full expression of one side breast from 436 urban Chinese lactating mothers at 5-11 days,12-30 days,31-60 days,61-120 days,and 121-240 days postpartum was obtained at 9：00 a.m.to 11：00 a.m.Total energy,lactose,protein,and fat contents were measured.24-hour dietary recall was surveyed,and maternal nutrient intakes were analyzed.Results Milk composition changed over the course of lactation and large individual variations were documented.The concentrations were 61.3 kcal/dl for total energy,7.1 g/dl for lactose,0.9 g/dl for protein,and 3.4 g/dl for fat in mature milk.Stage of lactation was a strong factor affecting milk composition.Minimal evidence was found for associations between maternal current dietary intake and milk macronutrient concentration,consistently with prior research.Maternal body mass index （BMI） was positively associated with milk fat content,to a greater extent than did dietary intake.All other maternal characteristics were not significant for milk composition.Conclusion These findings suggest that milk composition is generally weakly associated with maternal factors except for stage of lactation,and is likely to be more susceptible to long-term maternal nutritional status than short-term dietary fluctuation.展开更多
We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) ...We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.展开更多
An improved protocol has been developed for somatic embryogenesis and plant regeneration of recalcitrant cotton cultivars. High callus frequencies and embryogenic tissue were developed in MSB medium supplemented with ...An improved protocol has been developed for somatic embryogenesis and plant regeneration of recalcitrant cotton cultivars. High callus frequencies and embryogenic tissue were developed in MSB medium supplemented with gradient concentrations of KT and 2,4-D, their concentration decreasing from 0.1 to 0.01 mg·L^-1. Somatic embryos were successfully incubated in 1/2 macronutrient MSB suspension supplemented with 0.5 g· L^-1 glutamine and 0.5 g·L^-1 asparagine. Decrease in macronutrient concentration of MSB significantly alleviated browning and was beneficial to suspension cells. Transformation of somatic embryos into plants was induced in MSB medium supplemented with 3% sucrose, 0.5 g·L^-1 glutamine, 0.5 g·L^-1 asparagine, and 6.0 g·L^-1 agar. The effect of sucrose as carbohydrate was better than that of glucose for plant germination. Using this protocol, regenerated plantlets from the CCRI521 and Zhongzhi86-6 reached to as much as 19.6 and 18.5% somatic embryos, respectively.展开更多
文摘Background Infancy is a critical period of growth and physiological development,in which breast milk is the best source of nutrients.Compared to western countries,research on breast milk of Chinese population are limited.Thus,it is necessary to measure breast milk energy and macronutrient concentrations of healthy urban Chinese mothers at different lactation stages,to expand the database of milk composition of Chinese population,and to examine whether dietary or other maternal factors can affect the levels of macronutrients in breast milk.Methods Breast milk of full expression of one side breast from 436 urban Chinese lactating mothers at 5-11 days,12-30 days,31-60 days,61-120 days,and 121-240 days postpartum was obtained at 9：00 a.m.to 11：00 a.m.Total energy,lactose,protein,and fat contents were measured.24-hour dietary recall was surveyed,and maternal nutrient intakes were analyzed.Results Milk composition changed over the course of lactation and large individual variations were documented.The concentrations were 61.3 kcal/dl for total energy,7.1 g/dl for lactose,0.9 g/dl for protein,and 3.4 g/dl for fat in mature milk.Stage of lactation was a strong factor affecting milk composition.Minimal evidence was found for associations between maternal current dietary intake and milk macronutrient concentration,consistently with prior research.Maternal body mass index （BMI） was positively associated with milk fat content,to a greater extent than did dietary intake.All other maternal characteristics were not significant for milk composition.Conclusion These findings suggest that milk composition is generally weakly associated with maternal factors except for stage of lactation,and is likely to be more susceptible to long-term maternal nutritional status than short-term dietary fluctuation.
文摘We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.
文摘An improved protocol has been developed for somatic embryogenesis and plant regeneration of recalcitrant cotton cultivars. High callus frequencies and embryogenic tissue were developed in MSB medium supplemented with gradient concentrations of KT and 2,4-D, their concentration decreasing from 0.1 to 0.01 mg·L^-1. Somatic embryos were successfully incubated in 1/2 macronutrient MSB suspension supplemented with 0.5 g· L^-1 glutamine and 0.5 g·L^-1 asparagine. Decrease in macronutrient concentration of MSB significantly alleviated browning and was beneficial to suspension cells. Transformation of somatic embryos into plants was induced in MSB medium supplemented with 3% sucrose, 0.5 g·L^-1 glutamine, 0.5 g·L^-1 asparagine, and 6.0 g·L^-1 agar. The effect of sucrose as carbohydrate was better than that of glucose for plant germination. Using this protocol, regenerated plantlets from the CCRI521 and Zhongzhi86-6 reached to as much as 19.6 and 18.5% somatic embryos, respectively.
