Effect of repeated heating and cooling cycles on the pasting properties of starch

The properties of starch and starch–lipid pastes have been explored using a novel extended Rapid Visco Analyser (RVA) profile, in which the heating and cooling cycles are repeated five times. Starches from four wheat varieties with amylose content ranging from 23 to 27%, and waxy starches of wheat, rice and maize were tested, alone and in mixtures with lauric acid and monopalmitin (glyceryl-1-monopalmitin). Gels of all of the starches formed and melted reproducibly during repeated heating and cooling in the RVA. The addition of lauric acid to the waxy starches had no effect on the multiple RVA profile. Monopalmitin caused an increase in viscosity during the heating stage of the second to the fifth cycles with the waxy starches, which was attributed to the presence of monopalmitin aggregates. Changes in the multiple cycle viscosity traces observed when monopalmitin or lauric acid was added to the amylose-containing starches were complex. It was concluded that RVA paste viscosities were determined by starch–lipid interactions, as well as by free lipid in the starch mixtures. The water solubility of the lipid and association of proteins with starch granules influence these interactions.     

Evaluation of aggregate stability of Haplic Stagnosols using dynamic light scattering,phase analysis light scattering and color coordinates

Dynamic light scattering and phase analysis light scattering have been used to study organo-clay complexes and aggregate stability of Haplic Stagnosols depending on land use. The study of agricultural soils afforested for 45 years showed that the value of the effective diameter of organo-clay complexes slightly decreased compared to that in arable soil but remains still higher than that in the forest soil. Multiple linear regression statistical models were developed to predict the effective diameter of the particles. The best model (r = 0.95), where all parameters were significant (P < 0.05), included the clay content, clay carbon concentration, total iron (Fe_t) and soil color coordinates (L*, a*, b*). In the upper horizons, the effective diameter depends on the organic matter content, whereas iron oxides with surfaced position play the main role in the underlying horizons. Intensive tillage moves the colloidal system to coagulation and after withdrawal of arable Haplic Stagnosol from the agricultural production, the colloidal system tends to restore its peptization stability. However, it should be noted that the afforestation period (45 years) of arable Haplic Stagnosols is not enough for a full recovery of organo-clay complexes peptization stability.     

Extension of the concept of kinship, relationship, and inbreeding to account for linked epistatic complexes

Although epistatic effects are well defined and, in principle, can be exploited in quantitative-genetic selection theory, they often are ignored or even treated as nuisance parameters in practical applications. Traditionally, epistasis is considered as an interaction between genes at unspecified loci. Inspired by the observation that functional genes are often organised in physical clusters, we developed a model to combine additive effects and additive × additive interactions in linked gene clusters of defined length. Malécot's kinship concept is extended to identity by descent probabilities for chromosome segments of a given length in Morgan units, called epistatic kinship. Using the analogy of Malécot's kinship and Wright's relationship and inbreeding coefficients, epistatic relationship coefficients and epistatic inbreeding coefficients are defined. Simple rules are given to set up the epistatic numerator relationship matrix and its inverse directly from a pedigree list. The well-known single locus parameters and algorithms to set up the additive numerator relationship matrix and its inverse are a special case of the suggested methodology for a chromosome segment length of null Morgan. A proof of concept of the suggested method is given with a small simulation study. Assuming additive, linked epistatic and residual variance components, 100 replicated data sets for 1000 individuals are generated. From these data, residual maximum likelihood estimates of the variance components and of the chromosome segment size are obtained. Potential applications of the methodology are discussed. Given that a substantial variance component is attributed to this effect, the expected genetic gain can be increased on the short term if selection is on additive and epistatic effects, the latter comprising additive × additive interaction effect of loci in linkage disequilibrium. This extra benefit, however, will diminish through crossing over in subsequent generations. Despite some practical problems yet to be solved, the suggested model and algorithms open new perspectives to use a higher proportion of genetic variability in selection and breeding.     

Proliferative glomerulonephritis in experimental Leishmania donovani infection of the golden hamster

Extensive kidney involvement is reported in golden hamsters infected with Leishmania donovani. The lesion is characterised grossly by pale and enlarged kidneys, and histologically by thickening of the basal lamina of the glomerulus, distended convuluted tubules containing protein casts, constricted glomerular capillaries and infiltration of the interstitial tissues with mononuclear cells. Quantitative measurement of the glomerular cells labelled in vivo with tritiated thymidine showed a striking increase in the glomerular cell proliferation as the infection progressed. Using direct immunofluorescent technique, granular deposits of IgG, complement C₃ and fibrinogen were detected in the glomeruli of the infected animals. A positive protamine sulphate test, as well as histological evidence, showed that disseminated intravascular coagulation had occurred in the infection. Although the antigens have not been identified, antigen-antibody complexes are strongly implicated in the pathogenesis of the proliferative glomerulonephritis observed in this study.     

添喂赖氨酸席夫碱 铜配合物对绵羊瘤胃发酵的影响

选用4只体重约40 kg、安装永久性瘤胃瘘管的新疆美利奴羯羊按分期试验设计，分别添喂赖氨酸席夫碱-铜配合物0（第Ⅰ期）、4（第Ⅱ期）、8（第Ⅲ期）g/d·只，以研究不同水平的赖氨酸席夫碱 铜配合物对绵羊瘤胃发酵的影响。结果表明：随着添喂水平的提高，绵羊对玉米秸秆干物质的采食量增加，其中添喂量为8 g/d·只组与0 g/d·只组相比，采食量提高了12.5％（P＜0.05）。瘤胃液pH在4 g/d·只组与对照组之间无明显差异（P＞0.05），添喂8 g/d·只时在前3 h内具有明显减缓瘤胃液pH下降的作用。各组瘤胃液NH3-N含量差异不明显（P＞0.05），但8 g/d·只组的整体瘤胃液NH3-N含量有降低趋势。添喂赖氨酸席夫碱-铜配合物可降低乙酸和TVFA含量，提高丙酸和丁酸含量，使瘤胃发酵由乙酸型向丙酸型转变。本试验结果表明，添喂赖氨酸席夫碱 铜配合物对绵羊瘤胃发酵有一定的调节作用。     

Behaviour of cadmium and nickel in a soil amended with sewage sludge

Various urban and industrial sewage sludges were applied to a soil at two doses (50 and 100 t ha⁻¹ y⁻¹) during eight years in a field experiment. The soil was analysed at two depths (0–30 and 30–60 cm) for extractable cadmium and nickel. In general these trace metal increased with dosage. However, cadmium formed complexes with organic matter and nickel bound to iron and manganese oxides. Hence, the available fractions of these metals constituted a small proportion of the total content. The results obtained show a low risk of contamination due to the available fractions of these metals at sludges dosages of up to 100 t ha⁻¹. Copyright © 2001 John Wiley & Sons, Ltd.