Turnover of organic nitrogen in soils and its availability to crops

The root development of barley seedlings grown for one week in an aerated nutrient solution was studied in the presence of dissolved organic matter from an aqueous chestnut leaf litter extract. In particular, the different effects of low and high molecular weight fractions (small molecules: molecular weight <1000; large molecules: >10,000) of the leaf litter extract were examined. In the presence of large molecules root growth was inhibited, an irregular root tip morphology was observed, and Ca and Mg concentrations in the shoots were lower than in control plants. These phytotoxic effects were not caused by the formation of an impermeable layer of large molecules on the root surfaces that lower accessibility for nutrient cations as inferred from voltammetric experiments. A germination assay using spruce seeds, however, indicated allelochemical effects of large molecules, which exhibit a higher aromaticity than the small molecules as indicated by spectroscopic characterisation. In the growth experiments with small molecules, no influence on the root development of barley was evident, but an increase of Ca and Mg in the shoots was detected. During these growth experiments, a large amount of the small molecules, mainly simple phenols and amino acids, disappeared from the nutrient solution. The loss of small molecules was most likely the effect of mineralisation.Abbreviations DOC dissolved organic carbon - DOM dissolved organic matter - LLE leaf litter extract - MW molecular weight - HMDE hanging mercury drop electrode     

Molecular markers associated with seed weight in two soybean populations

Seed weight (SW) is a component of soybean, Glycine max (L.) Merr., seed yield, as well as an important trait for food-type soybeans. Two soybean populations, 120 F₄-derived lines of YoungxPI416937 (Pop1) and 111 F₂-derived lines of PI97100xCoker 237 (Pop2), were mapped with RFLP makers to identify quantitative trait loci (QTLs) conditioning SW across environments and populations. The genetic map of Pop1 consisted of 155 loci covering 973 cM, whereas Pop2 involved 153 loci and covered 1600 cM of map distance. For Pop1, the phenotypic data were collected from Plains, GA., Windblow, N.C., and Plymouth, N.C., in 1994. For Pop2, data were collected from Athens, GA., in 1994 and 1995, and Blackville, S.C., in 1995. Based on single-factor analysis of variance (ANOVA), seven and nine independent loci were associated with SW in Pop1 and Pop2, respectively. Together the loci explained 73% of the variability in SW in Pop1 and 74% in Pop2. Transgressive segregation occurred among the progeny in both populations. The marker loci associated with SW were highly consistent across environments and years. Two QTLs on linkage group (LG) F and K were located at similar genomic regions in both populations. The high consistency of QTLs across environments indicates that effective marker-assisted selection is feasible for soybean SW.     

Effect of bicarbonate and root zone temperature on uptake of Zn,Fe, Mn and Cu by different rice cultivars (Oryza sativa L.) grown in calcareous soil

Pot experiments were conducted with a calcareous soil (Inceptisol) to elucidate the effects of bicarbonate (0 and 20 mM) and root zone temperature (15° and 25°C) on the uptake of Zn, Fe, Mn and Cu by "Zn-efficient" and "Zn-inefficient" rice cultivars. Bicarbonate decreased concentrations and total uptake of Zn in shoots of "Zn-inefficient" cultivars, especially of IR 26 at 25°C, but not in Zn-efficient cultivars. Bicarbonate decreased concentrations and uptake of Fe in shoots of Zn inefficient cultivars, particularly in IR 26. Concentrations and total uptake of Mn were lower in bicarbonate treatment in the Zn-inefficient cultivars at 15°C, and in all cultivars at 25°C. However, concentration and uptake of Cu were not affected by bicarbonate in all cultivars. Compared to the 25°C root zone temperature, the concentrations and total uptake of both Zn and Cu in shoots at 15°C were lower in Zn-inefficient than in the Zn-efficient cultivars. The results indicate that Zn-efficiency in rice is causally related to high tolerance of plant to elavated bicarbonate concentrations in soil solution.     

Petite bodies of the “robust” australopithecines

The “robust” australopithecines are often depicted as having large and powerfully built bodies to match their massive masticatory apparatus, but until 1988 the sample of postcranial remains attributed with certainty to this group was very limited. Almost nothing was known about the body of the East African “robust” australopithecine because taxonomic attribution of the postcrania was so uncertain. The body of the South African “robust” australopithecine had to be reconstructed from about a dozen isolated fragments of postcrania. Now a partial skeleton is attributed with confidence to the East African “robust” group along with several isolated bones. The South African sample has more than tripled. Analyses of this vastly expanded sample reveal that a large portion of postcrania attributed to “robust” australopithecines from Swartkrans Member 1 (35%) are from extraordinarily small-bodied individuals similar in size to a modern Pygmy weighing as little as 28 kg. These small elements include parts from the forelimb, spine, and hindlimb. About 22% of these Swartkrans 1 “robust” australopithecines are about the same size as a modern human weighing about 43 kgs and about 43% are larger than this standard but less than or equal to a 54 kg modern human. Approximately the same pattern is true for the Swartkrans 2 hominids, but taxonomic attribution is less certain. All of the Member 3 specimens are similar in size to the 45 kg standard. The partial skeleton of the East African “robust” australopithecine (KNM-ER 1500) has hindlimb joints that would correspond to a modern human of 34 kgs although the actual weight may be 5 to 10 kgs greater judging from shaft robusticity and forelimb size. The largest postcranial element attributed with some certainty to the East African “robust” australopithecine group (the talus, KNM-ER 1464) is about the same overall size as a modern human of 54 kgs, although its tibial facet is slightly smaller. Although many previous studies have hinted at the possibility that “robust” australopithecines had relatively small bodies, the new fossils provide substantial evidence that these creatures ranged from quite small to only moderate in body size relative to modern humans. These were the petite-bodied vegetarian cousins of our ancestors. Sexual dimorphism in body size appears to be greater than that in modern humans, similar to that in Pan, and less than that in Gorilla or Pongo, although such comparisons are of limited value given the small samples, poorly known body proportions, time averaging, and many other problems.     

Birth Weight and Its Relationship to Size Attained and Relative Fat Distribution at 7 to 12 Years of Age

The relationship between birth weight and relative subcutaneous fat distribution at school age was considered in 131 boys and 106 girls 7 to 12 years of age. Relative fat distribution at school age was estimated with the ratio of the subscapular to triceps skinfolds (S/T) for the total sample, and with the ratio of the sum of two trunk (subscapular, midaxillary) to the sum of two extremity (triceps, medial calf) skinfolds (T/E) for subsamples of 102 boys and 63 girls. There were no sex differences in the S/T ratio (mm/mm), boys 0.62 ± 0.15, girls 0.63 ± 0.18; T/E ratio (mm/mm), boys 0.58 ± 0.13, girls 0.59 ± 0.16; and BMI (kg/m²), boys 17.1 ± 2.4, girls 16.9 ± 2.2. Second order partial correlations, controlling for age and the BMI or age and sum of skinfolds, between birth weight and the skinfold ratios are, respectively, ?0.22 and ?0.20 (p<0.01) for S/T and ?0.29 and ?032 (p<0.01) for T/E in girls, and ?0.18 and ?0.17 (p<0.05) for S/T and ?0.06 and ?0.6 for T/E in boys. Though low, the correlations suggest that as birth weight decreases proportionally more subcutaneous fat is accumulated on the trunk than on the extremities, more so in females than in males. Results of stepwise multiple regression analyses indicate that birth weight accounts for from 2% to 8% of the variance in relative subcutaneous fat distribution at school age.     

Construct Validity of the Impact of Weight on Quality of Life Questionnaire

KOLOTKIN, RONETTE L, SUSAN HEAD, ALAN BROOKHART. Construct validity of the Impact of Weight on Quality of Life questionnaire. The Impact of Weight on Quality of Life questionnaire (IWQOL) is a 74-item self-report, condition-specific instrument that (1) assesses the effect of weight on quality of life in eight key areas, and (2) may be used as a treatment outcome measure and/or an evaluation tool for healthcare policy makers and third-party payers. This study explores IWQOL construct validity and provides new information on internal consistency, treatment effects, and differences between men and women. IWQOL total scores correlated highly with other measures of overall quality of life, and subscale scores correlated well with counterparts in the assessment battery. Internal consistency estimates for the IWQOL scales generally were high. For the women, 4-week participants, and the total sample, pretreatment-posttreatment differences were significant for all IWQOL scales and total score. For men, treatment differences were significant for the total score and all subscales except for Work and Mobility. Treatment differences for 2-week participants were significant for all scales except for Work. Consistent with previous IWQOL study results, the Comfort With Food scale scores reflected more discomfort at posttreatment as compared with pretreatment. The IWQOL, already translated into French and Italian, currently is demonstrating clinical and research utility as a quality-of-life outcome measure for clinical trials of antiobesity drugs and surgical treatments for patients with obesity.     

Age-related changes in body weight,scrotal size and plasma testosterone levels in buffalo bulls (Bubalus bubalis)

Body weight, testicle size and peripheral testosterone concentrations were measured in 35 water buffalo bulls at 5, 15, 17, 21, 25 and 38 months of age. These parameters were studied in all animals during the same month (October), so the changes due to age were independent of changes in photoperiod and temperature. Body weight increased linearly with age. The testicular size measured in terms of scrotal circumference as related to age, showed a curvilinear increase; the average rate of testicular growth was maximum between 15 and 25 months. Plasma testosterone levels were low between 5 and 21 months. A significant rise in plasma concentration of testosterone was observed at 25 months reaching peak levels at 38 months. The mean age of sexually mature bulls at the time of first ejaculation of semen with motile sperm, was 24.9±0.9 months (n=9). It has been concluded that in the Nili-Ravi buffalo bulls the sexually quiescent period (prepubertal) extends up to 15 months of age and sexual maturation as indicated by the presence of motile sperm in the ejaculate is attained at about 25 months.     

Critical importance of microsome concentration in mutagenesis assay with V79 Chinese hamster cells.

For optimum mutagensis in V79 Chinese hamster cells, the amount of liver postmitochondrial fraction in the assay was found to be of critical importance, depending on the chemicals being tested. Benzo[a]pyrene (BP) required lower (1-5%) concentrations of the liver 15 000 X g supernatant (S15) from methylcholanthrene pretreated rats for a maximum induction of cytotoxicity and mutagenicity, as determined by 8-azaguanine- and ouabain-resistance. A sharp peak of mutagenicity and cytotoxicity was induced by 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (7,8-diol BP) at a concentration of 1% of the S15 fraction. Little or no response was induced by these compounds with the S15 concentrations of more than 10%. Similarly, aflatoxin B1 induced a sharp peak of mutagenicity and cytotoxicity at a concentration of 2% of the liver S15 fraction from Aroclor-pretreated rats. Under the same condition, non-carcinogenic aflatoxin G2 did not induce cytotoxicity and mutagenicity. Analysis of BP metabolites by high-pressure liquid chromatography indicates that with the 30% S15 fraction, more than 80% of BP was metabolized during the first 15 min, while with the 2% S15 fraction, 7,8-diol BP increased continuously throughout the 120-min incubation period, suggesting a strong metabolic competition to rapidly remove BP and 7,8-diol BP with a high concentration of the S15. In contrast with these compounds, N-nitrosodimethylamine induced mutagenicity and cytotoxicity which increased linearly in proportion to the increasing amount of the S15 fraction from phenobarbitone- and Aroclor-pretreated rats. Various nitrosamines with different lipophilicity were examined at a high (30%) and low (2%) concentration of the S15 fraction from Aroclor-pretreated rats, in which ratios of mutation frequencies at 30% and 2% correlated inversely with lipophilicity of the compound. This result suggests that the lipid solubility of test compounds may be one factor which determines the concentration of post-mitochondrial supernatant for optimum mutagenesis.     

Rat and human embryo and post-natal sera contain a potent endogenous competitor of estrogen-rat alpha-fetoprotein interactions

A highly active inhibitor of the binding of estrone and estradiol-17β to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH₂₀ and thin layer chromatography : it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17β anti-bodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed.     

Continuous culture system for production of biopolymer levan using erwinia herbicola

The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and (13)C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.