A review of the use of the basic cation saturation ratio and the "ideal" soil

The use of 'balanced' Ca, Mg, and K ratios, as prescribed by the basic cation saturation ratio (BCSR) concept, is still used by some private soil-testing laboratories for the interpretation of soil analytical data. This review aims to examine the suitability of the BCSR concept as a method for the interpretation of soil analytical data. According to the BCSR concept, maximum plant growth will be achieved only when the soil’s exchangeable Ca, Mg, and K concentrations are approximately 65 % Ca, 10 % Mg, and 5 % K (termed the ‘ideal soil’). This ‘ideal soil’ was originally proposed by Firman Bear and co-workers in New Jersey (USA) during the 1940s as a method of reducing luxury K uptake by alfalfa (Medicago sativa L.). At about the same time, William Albrecht, working in Missouri (USA), concluded through his own investigations that plants require a soil with a high Ca saturation for optimal growth. Whilst it now appears that several of Albrecht’s experiments were fundamentally flawed, the BCSR (‘balanced soil’) concept has been widely promoted, suggesting that the prescribed cationic ratios provide optimum chemical, physical, and biological soil properties. Our examination of data from numerous studies (particularly those of Albrecht and Bear, themselves) would suggest that, within the ranges commonly found in soils, the chemical, physical, and biological fertility of a soil is generally not influenced by the ratios of Ca, Mg, and K. The data do not support the claims of the BCSR, and continued promotion of the BCSR will result in the inefficient use of resources in agriculture and horticulture.

Economic, social and cultural influences on the status and wellbeing of Indian rural wives

Examines the status and well being of wives in rural India using results from interviews. Surveys were conducted in three villages in the southwest of West Bengal and in three villages in the west of Orissa. The survey in West Bengal contained a large proportion of Santal tribals and the Oriyan survey was dominated by Kondh tribals. The relationships between variables representing economic, social and cultural factors are compared with ‘dependent’ variables representing the status of wives within their family and their wellbeing. Wellbeing is indicated by whether the basic needs of wives for food and medical care are met. Status of wives is indicated by their ‘control’ over family resources, whether or not they are restricted in joining social groups and in working outside their home, and the extent of their involvement in family decision-making. Cultural factors are found to be the dominant influence on the status of wives. Family income and other economic factors are found to be associated cross sectionally with greater restrictions on wives within their family. Nevertheless, the higher in the economic status of the household, the more likely are the basic needs of wives to be met.

Contraction of the human diaphragm during rapid postural adjustments

1. The response of the diaphragm to the postural perturbation produced by rapid flexion of the shoulder to a visual stimulus was evaluated in standing subjects. Gastric, oesophageal and transdiaphragmatic pressures were measured together with intramuscular and oesophageal recordings of electromyographic activity (EMG) in the diaphragm. To assess the mechanics of contraction of the diaphragm, dynamic changes in the length of the diaphragm were measured with ultrasonography. 2. With rapid flexion of the shoulder in response to a visual stimulus, EMG-activity in the costal and crural diaphragm occurred about 20 ms prior to the onset of deltoid EMG. This anticipatory contraction occurred irrespective of the phase of respiration in which arm movement began. The onset of diaphragm EMG-coincided with that of transversus abdominis. 3. Gastric and transdiaphragmatic pressures increased in association with the rapid arm flexion by 13.8 +/- 1.9 (mean +/- S.E.M.) and 13.5 +/- 1.8 cmH(2)O, respectively. The increases occurred 49 +/- 4 ms after the onset of diaphragm EMG, but preceded the onset of movement of the limb by 63 +/- 7 ms. 4. Ultrasonographic measurements revealed that the costal diaphragm shortened and then lengthened progressively during the increase in transdiaphragmatic pressure. 5. This study provides definitive evidence that the human diaphragm is involved in the control of postural stability during sudden voluntary movement of the limbs.

Functional polymorphism of the human arylamine N-acetyltransferase type 1 gene caused by (CT)-T-190 and G(560)A mutations

Human N-acetyltransferase type 1 (NAT1) catalyses the N- or O-acetylation of various arylamine and heterocyclic amine substrates and is able to bioactivate several known carcinogens. Despite wide inter-individual variability in activity, historically, NAT1 was considered to be monomorphic in nature. However, recent reports of allelic variation at the NAT1 locus suggest that it may be a polymorphically expressed enzyme. In the present study, peripheral blood mononuclear cell NAT1 activity in 85 individuals was found to be bimodally distributed with approximately 8% of the population being slow acetylators. Subsequent sequencing of the individuals having slow acetylator status showed all to have either a (CT)-T-190 or G(560)A base substitution located in the protein encoding region of the NAT1 gene. The (CT)-T-190 base substitution changed a highly conserved Arg(64), which others have shown to be essential for fully functional NAT1 protein. The (CT)-T-190 mutation has not been reported previously and we have named it NAT1*17. The G(560)A mutation is associated with the base substitutions previously observed in the NAT1*10 allele and this variant (NAT1*14) encodes for a protein with reduced acetylation capacity. A novel method using linear PCR and dideoxy terminators was developed for the detection of NAT1*14 and NAT1*17. Neither of these variants was found in the rapid acetylator population. We conclude that both the (CT)-T-190 (NAT1*17) and G(560)A (NAT1*14) NAT1 structural variants are involved in a distinct NAT1 polymorphism. Because NAT1 can bioactivate several carcinogens, this polymorphism may have implications for cancer risk in individual subjects. (C) 1998 Chapman & Hall Ltd.

Structural and functional characterisation of human sulfotransferases

The human aryl sulfotransferases HAST4 and HAST4v vary by only two amino acids but exhibit markedly different affinity towards the sulfonate acceptor p-nitrophenol and the sulfonate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS). To determine the importance of each of these amino acid differences, chimeric constructs were made of HAST4 and HAST4v. By attaching the last 120 amino acids of HAST-4v to HAST4 (changing Thr235 to Asn235) we have been able to produce a protein that has a K-m for PAPS similar to HAST4v. The reverse construct, HAST4v/4 produces a protein with a K-m for PAPS similar to HAST4. These data suggests that the COOH-terminal of sulfotransferases is involved in co-factor binding. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

Bacterial expression of two human aryl sulfotransferases

The effect of replacing a single codon in the N-terminal of human aryl sulfotransferase (HAST) 1 and 3 with one that is more commonly found in E. coli genes was assessed. The pKK233-2 E. coli expression vector was employed and the polymerase chain reaction (PCR) was used to introduce the 5' nucleotide substitution, at the same time maintaining the fidelity of the amino acid sequence. The data indicates that this change had a minimal effect on protein production, subcellular localization or, in the case of HAST3, catalytic activity. In general, the pKK233-2 E. coli vector has been less than optimal for expressing human sulfotransferase cDNAs. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.