Heterozygous germ line hCHK2 mutations in Li-Fraumeni syndrome

The hCHK2 gene encodes the human homolog of the yeast Cds1 and Rad53 G2 checkpoint kinases, whose activation in response to DNA damage prevents cellular entry into mitosis. Here, it is shown that heterozygous germ line mutations in hCHK2 occur in Li-Fraumeni syndrome, a highly penetrant familial cancer phenotype usually associated with inherited mutations in the TP53 gene. These observations suggest that hCHK2 is a tumor suppressor gene conferring predisposition to sarcoma, breast cancer, and brain tumors, and they also provide a link between the central role of p53 inactivation in human cancer and the well-defined G2 checkpoint in yeast.     

Male Lek Formation and Female Calling in a Population of the Arctiid Moth Estigmene acrea

Abdominal coremata in male Estigmene acrea (Lepidoptera: Arctiidae) are inflated and displayed in aggregations to which females and males are attracted and where mating occurs (leks). Female E. acrea also release a sex pheromone which attracts males. These two mating behaviors occur in the same populations at different peak times on the same nights. Thus male lek formation and female calling occur in the same species, and the male coremata, or related structures, appear to be integrally associated with lek behavior.     

REVIEW: Aroma of Wheat Bread Crumb

Bread aroma is an important parameter for bread quality, and this review aims to provide an overview of aroma compounds identified in bread crumb and how these compounds are formed. More than 150 volatile compounds were identified in bread crumb, and they mainly originated from the fermentative activity of yeast, from oxidation of flour lipids, and to a lower extent from Maillard reactions. Of those volatile compounds, 45 compounds can be characterized as aroma compounds, because they most likely can be sensed when the bread is eaten because of their high odor activity values and flavor dilution factors. The influence of ingredients and mixing conditions on bread aroma has scarcely been investigated. The fermentation conditions (yeast level and strain as well as fermentation temperature and time) were found to significantly influence the aroma of bread crumb. Yeast level and strain mainly influence formation of compounds directly related to the fermentative activity of yeast, whereas fermentation temperature and time also influence formation of compounds from oxidation of flour lipids.     

Estimation of wood density and chemical composition by means of diffuse reflectance mid-infrared Fourier transform (DRIFT-MIR) spectroscopy

Sitka spruce (Picea sitchensis) samples (491) from 50 different clones as well as 24 different tropical hardwoods and 20 Scots pine (Pinus sylvestris) samples were used to construct diffuse reflectance mid-infrared Fourier transform (DRIFT-MIR) based partial least squares (PLS) calibrations on lignin, cellulose, and wood resin contents and densities. Calibrations for density, lignin, and cellulose were established for all wood species combined into one data set as well as for the separate Sitka spruce data set. Relationships between wood resin and MIR data were constructed for the Sitka spruce data set as well as the combined Scots pine and Sitka spruce data sets. Calibrations containing only five wavenumbers instead of spectral ranges 4000-2800 and 1800-700 cm(-1) were also established. In addition, chemical factors contributing to wood density were studied. Chemical composition and density assessed from DRIFT-MIR calibrations had R2 and Q2 values in the ranges of 0.6-0.9 and 0.6-0.8, respectively. The PLS models gave residual mean squares error of prediction (RMSEP) values of 1.6-1.9, 2.8-3.7, and 0.4 for lignin, cellulose, and wood resin contents, respectively. Density test sets had RMSEP values ranging from 50 to 56. Reduced amount of wavenumbers can be utilized to predict the chemical composition and density of a wood, which should allow measurements of these properties using a hand-held device. MIR spectral data indicated that low-density samples had somewhat higher lignin contents than high-density samples. Correspondingly, high-density samples contained slightly more polysaccharides than low-density samples. This observation was consistent with the wet chemical data.     

Influence of soil properties on the aggregate stability of cultivated sandy clay loams

Purpose

Frequent cultivation and overhead irrigation have led to severe surface crusting, erosion and poor irrigation performance on sandy clay loam soils in the Coal River Valley, Tasmania, Australia. This study was established to identify the key soil properties related to aggregate breakdown determined by different methods, and explore options for reducing soil crusting.

Materials and methods

Soil aggregates were collected from 0 to 5 cm depth from 20 sites managed for packet salad and lettuce production. The stability of air-dried 2.00–4.75 mm aggregates was determined by rainfall simulation, wet sieving and clay dispersion. Soil aggregates were analysed for particle size, mineralogy, soluble and exchangeable cations, pH, EC, labile carbon and total carbon. The association between aggregate stability and the measured soil properties was explored using Spearman correlation, linear regression and regression tree analysis.

Result and discussion

Aggregate stability determined by rainfall simulation was closely associated with soil properties that promote aggregation, including effective cation exchangeable capacity (ECEC) and the proportion of polyvalent cations (Ca²⁺, Al³⁺). In contrast, aggregate stability determined by wet sieving was associated with soil properties that promote disaggregation, including quartz and sand content, and to lesser extent, the proportion of monovalent cations (especially K⁺). Clay dispersion was closely associated with pH, quartz content, soil texture and the sodium adsorption ratio. Soil carbon appeared to have only moderate influence on aggregate stability, but not clay dispersion, while labile carbon was not significantly related to any measure of aggregate stability or clay dispersion. Similarly, the proportion of Na⁺ ions was not related to either measure of aggregate stability and was only moderately related to clay dispersion.

Conclusions

Options for improving aggregate stability appear limited as aggregate stability was strongly related to the content of inherent soil properties such as sand/quartz and smectite contents. However, high correlation between exchangeable Ca²⁺ and aggregate stability determined by rainfall simulation indicates that soil crusting may be reduced through application of products that rich in Ca²⁺ such as gypsum.

     

The influence of drought on the survival of eggs of Austroicetes cruciata, Sauss

Ohne Zusammenfassung

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The influence of drought on the survival of eggs of Austroicetes cruciata, Sauss

     

Soil organic matter decline and compositional change associated with cereal cropping in southern Tanzania

The spatial analogue method and ¹³C analytical techniques were used to reveal medium‐ to long‐term changes in soil organic matter (SOM) in farmers' fields under maize in southern Tanzania. Aerial photography and detailed farmer interviews were used to relate land‐use history to declines in SOM concentration and changes in composition. The research attempted to measure the rate of SOM decline and the extent to which farmers' residue management practice was allowing cereal residues to contribute to SOM. The combination of research methods employed in this study proved to be highly complementary. Results indicate that native SOM decreased by on average 50 per cent; after 25 years of cultivation. Under current residue management with cereal residues mostly grazed and burnt there is only a relatively modest contribution from cereal residues to SOM. When cereal residues are retained in the field it is likely they will contribute significantly to SOM but they are much less likely to build SOM in the medium to long term. The paper concludes that in many situations it is probably best for farmers to allow the majority of the residues to be eaten by cattle in these systems rather than attempt to build SOM or risk nitrogen immobilization in cropped fields. The greater importance of inputs of high‐quality (e.g. legume) residues for nutrient supply in the short term is highlighted, in contrast to inputs of poor‐quality (e.g. cereal) residues in an attempt to build SOM in the longer term. Copyright © 2001 John Wiley & Sons, Ltd.