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Notizen: Objective To investigate whether low maternal haemoglobin and ferritin levels are associated with increased placental volume by mid-pregnancy.Design Prospective study of women attending hospital for shared antenatal care.Setting A teaching hospital in the south of England.Subjects Five hundred and sixty-eight women booking for delivery in the hospital.Main outcome measures Placental volume measured by ultrasound at 18 weeks gestation.Results At 14 weeks gestation 9% of women had haemoglobin levels ≤ 11 g/dl and 26% had ferritin levels 〈 13 μg/1. Placental volume at 18 weeks was inversely related to the maternal haemoglobin and ferritin levels. The influence of haemoglobin and ferritin concentrations was independent of maternal social class, parity, smoking, and weight. Larger placentae were found in taller women, those who had previously been pregnant, and in those who were smoking more than 15 cigarettes daily at the time of their last menstrual period.Conclusion These data suggest that placental development is influenced from early in pregnancy by the intrauterine environment provided by the mother. In conjunction with other studies they support the proposal that, as a result of these changes, programming of adult blood pressure may be initiated in early pregnancy.

Notizen: Objective To examine the relation between indices of maternal nutrition during pregnancy, including haemoglobin concentration, skinfold thickness and body weight, and the child's blood pressure at 10 to 12 years of age.Design Follow up study of children whose mothers had haemoglobin estimations, weights and skinfold thicknesses recorded during pregnancy.Setting Kingston, Jamaica.Subjects Seventy-seven children whose mothers took part in a prospective study of nutrition during pregnancy in relation to fetal growth.Main outcome measure Blood pressure at 10 to 12 years of age.Results The child's mean systolic pressure adjusted for current weight rose by 2.6 mmHg (95 % CI 0.5–4.6, P= 0.01) for each 1 g/dl fall in the mother's lowest haemoglobin during pregnancy. Mothers with a lower haemoglobin had thinner skinfold thicknesses, especially over the triceps (P= 0.005). In multiple regression analyses, taking account of the child's sex and current weight, there was a strong association between thin maternal triceps skinfold thickness at 15 weeks of gestation and raised blood pressure in the offspring. Taking account of the mother's triceps skinfold thickness abolished the relation between lower haemoglobin and raised blood pressure in the child. Lower weight gain between 15 and 35 weeks of gestation was independently associated with raised children's blood pressure. Systolic pressure rose by 10.7 mmHg (95 % CI 5.7 to 15.6, P= 0.0001) for each log mm decrease in the mother's triceps skinfold thickness, and by 0.6 mmHg (95% CI 0.1 to 1.0, P= 0.02) for each 1 kg decrease in the mother's weight gain during pregnancy.Conclusions These results parallel animal experiments suggesting that impaired maternal nutrition may underlie the programming of adult hypertension during fetal life.

Notizen: Fingerprint whorl patterns are formed during fetal life. In a group of 180 term infants, those with more fingerprint whorls tended to have a small abdominal circumference (P= 0.09) and high ratio of head to abdominal circumference (P= 0.008). These associations were independent of the relation between the whorl counts of the mothers and their infants. We also found an independent correlation between the babies’ whorl count and the combination of increasing subscapular (P= 0.03) and decreasing triceps (P= 0.02) skinfold thicknesses of the mothers. Whorl patterns are associated with adult hypertension; maternal nutritional status may influence their common origin during fetal development.

Notizen: Objective To examine how maternal diet in pregnancy and parental body size and birthweight influence an infant's thinness at birth measured by a low ponderal index.Design An observational study of newborn infants and their parents.Setting Southampton, England.Population Five hundred and thirty-eight infants born at term.Main outcome measure Ponderal index at birth.Results Women who had a high intake of carbohydrate in early pregnancy and a low intake of dairy protein in late pregnancy tended to have infants that were thin at birth (P= 0.01 and P= 0.03, respectively, in a simultaneous analysis). Women who themselves had a low birthweight also tended to have thin infants, ponderal index falling from 28.3 kg/m3 to 26.2 kg/m3 as the women's birthweights decreased from more than 4.0 kg to 2.5 kg or less (P 〈 0.0001). Tall fathers had thin infants, but ponderal index was not related to the women's heights or the fathers’ birthweights.Conclusion These associations may reflect constraints on placental development imposed by a woman's nutrition in pregnancy and during her own intrauterine life. Effects of the father's height may be mediated through genetic influences on skeletal growth.

Notizen: Objective— To examine the maternal influences which determine large placental weight and a high ratio of placental weight to birthweight. These are known predictors of adult blood pressure.Design— Retrospective analysis of routine obstetric and haematology department records for a large cohort of pregnant women.Setting— John Radeliffe Hospital, Oxford.Subjects— 8684 pregnant women who were delivered between January 1987 and January 1989 and whose records could be linked to the results of two or more pregnancy blood counts.Main outcome measures— Placental weight and the ratio of placental weight to birthweight.Results— Large placental weight was associated with a low maternal haemoglobin and a fall in maternal mean cell volume during pregnancy. The highest ratio of placental weight to birthweight occurred in the most anaemic women with the largest falls in mean cell volume. Large placental weight and a high ratio of placental weight to birthweight were also independently associated with a high maternal body mass index. Maternal smoking reduced placental weight, but increased the ratio of placental weight to birthweight.Conclusions— Anaemia and iron deficiency during pregnancy are associated with large placental weight and a high ratio of placental weight to birthweight. This points to maternal nutritional deficiency as a cause for discordance between placental and fetal growth. This may have important implications for the prevention of adult hypertension, which appears to have its origin in fetal life.

Notizen: Prior work demonstrated that Heuchera americana, an evergreen herb inhabiting the deciduous forest understory in the southeastern United States, has a 3-4-fold greater photosynthetic capacity under the low-temperature, strong-light, open canopies of winter compared to the high-temperature, weak-light, closed canopies of summer. Moreover, despite the reductions in soil nitrogen, the chilling temperatures, and the increased quantum flux associated with winter, chronic photoinhibition was not observed in this species at this time of the year. We were interested in the photosynthetic acclimation and photoinhibition characteristics of this species when grown under contrasting light and nitrogen regimes. Newly expanded shade-acclimated leaves of forest-grown plants exposed to strong light varying in intensity and duration at 25°C showed a reduction in Fv/Fm (the ratio of variable to maximum room temperature chlorophyll fluorescence measured after dark adaptation), which was correlated with a decline in øa (the intrinsic quantum yield of CO2-saturated O2 evolution on an absorbed light basis). Plants grown in the glasshouse under contrasting light (high and low light; HL and LL, respectively) and nitrogen supply (high and low nitrogen; HN and LN, respectively) regimes showed that photosynthetic acclimation to HL was impaired in LN regimes. The HL-LN plants also had the lowest values of Fv/Fm and of ø on both incident and absorbed light bases and had 50% less chlorophyll (per unit area) compared to plants from other growth regimes. Controlled exposure to bright light at low temperatures (2-3°C) for 3 h resulted in a sharp decrease in Fv/Fm (and rise in Fo, the minimum fluorescence yield) in all plants. Shade-grown plants from both N regimes were highly susceptible to chronic photoinhibition, as indicated by a greater reduction in Fv/Fm and incomplete recovery after 18 h in weak light at 25°C. The HL-HN plants were the least susceptible to chronic photoinhibition, having the smallest decrease in Fv/Fm with near full recovery within 6 h. The decline in Fv/Fm in HL-LN plants was comparable to that of shade-acclimated plants, but recovered fully within 6 h. Low-N plants from both light regimes displayed greater increases in Fo which did not return to pretreatment levels after 18 h of recovery. These studies indicate that HL-LN plants were sensitive to chronic photoinhibition and, at the same time, had a high capacity for dynamic photoinhibition. Experimental garden studies showed that H. americana grown in an open field in summer were photoinhibited and did not fully recover overnight or during extended periods of weak light. These results are discussed in relation to the photosynthetic acclimation of H. americana under natural conditions.

Notizen: The effects of introduced chloroplast gene mutations affecting D1 synthesis, turnover and function on photosynthesis, growth and competitive ability were examined in autotrophic cultures of Chlamydomonas reinhardtii (Chlorophyta) adapted to low or high irradiance. Few discernible effects were evident when the mutants were grown in low light (LL, 70 μmol m−2 s−1). The herbicide-resistant psbA mutation Ser264→ Ala (dr) slowed electron transfer and accelerated D1 degradation in cells grown under high light (HL, 600 μmol m−2 s−1). The maximum rate of light-and CO2-saturated photosynthesis, cell growth rate and competitive ability in the dr mutant were reduced compared to wild type under HL. However, the wild-type rate of D1 synthesis in dr was adequate to compensate for accelerated D1 degradation. 16S rRNA mutations conferring resistance to streptomycin and spectinomycin (spr/sr) that altered chloroplast ribosome structure and assembly were used to inhibit chloroplast protein synthesis. In spr/sr cells grown under HL, D1 synthesis was reduced by 40–60% compared to wild type and D1 degradation was accelerated, leading to a 4-fold reduction in D1 pool size. The reduced D1 levels were accompanied by an elevation of Fo and a decline in Fv/Fm, quantum yield and maximum rate of CO2-saturated photosynthesis. Chemostat experiments showed that the growth rate and competitive ability of spr/sr were reduced against both wild type and dr.

Notizen: Two direct but independent approaches were developed to identify the average δ18O value of the water fraction in the chloroplasts of transpiring leaves. In the first approach, we used the δ18O value of CO2 in isotopic equilibrium with leaf water to reconstruct the δ18O value of water in the chloroplasts. This method was based on the idea that the enzyme carbonic anhydrase facilitates isotopic equilibrium between CO2 and H2O predominantly in the chloroplasts, at a rate that is several orders of magnitude faster than the non-catalysed exchange in other leaf water fractions. In the second approach, we measured the δ18O value of O2 from photosynthetic water oxidation in the chloroplasts of intact leaves. Since O2 is produced from chloroplast water irreversibly and without discrimination, the δ18O value of the O2 should be identical to that of chloroplast water. In intact, transpiring leaves of sunflower (Helianthus annuus cv. giant mammoth) under the experimental conditions used, the average δ18O value of chloroplasts water was displaced by 3—10 % (depending on relative humidity and atmospheric composition) below the value predicted by the conventional Craig & Gordon model. Furthermore, this δ18O value was always lower than the δ18O value that was measured for bulk leaf water. Our results have implications for a variety of environmental studies since it is the δ18O value of water in the chloroplasts that is the relevant quantity in considering terrestrial plants influence on the δ18O values of atmospheric CO2 and O2, as well as in influencing the δ18O of plant organic matter.