Validation of a method to determine transformation of chemicals in anaerobic liquid pig and cattle manure for the OECD test guideline programme

Manure is widely used as a fertilizer and applied to agricultural land. It may contain highly active chemicals like veterinary medicinal products or biocides, which enter into the environment by this pathway. This is recognized by several regulatory frameworks, however, a detailed method for examining the transformation of chemicals in manure was lacking. This article describes the validation of a method for studying the anaerobic transformation of chemicals in pig and cattle liquid manure. Different steps are covered with an emphasis on the validation ring test and the OECD (Organisation for Economic Cooperation and Development) process that led to the recent adoption of the method as OECD Test Guideline (TG) 320.

A precise method to determine the angular distribution of backscattered light to high angles

We present an approach to measure the angular dependence of the diffusely scattered intensity of a multiple scattering sample in backscattering geometry. Increasing scattering strength give rise to an increased width of the coherent backscattering and sets higher demands on the angular detection range. This is of particular interest in the search for the transition to Anderson localization of light. To cover a range of -60 degrees to +85 degrees from direct back-reflection, we introduced a new parallel intensity recording technique. This allows one-shot measurements, with fast alignment and short measuring time, which prevents the influence of illumination variations. Configurational average is achieved by rotating the sample and singly scattered light is suppressed with the use of circularly polarized light up to 97%. This implies that backscattering enhancements of almost two can be achieved. In combination with a standard setup for measuring small angles up to +/-3 degrees , a full characterization of the coherent backscattering cone can be achieved. With this setup we are able to accurately determine transport mean free paths as low as 235 nm.

Testosterone-induced changes in phosphatidylcholine molecular species composition of Plasmodium chabaudi-infected erythrocytes

This study is concerned with the influence of testosterone on the phospholipid class and the phosphatidylcholine molecular species composition of various fractions obtained from the blood of Plasmodium chabaudi-infected mice. Blood plasma, infected erythrocytes, isolated parasites and erythrocyte membranes isolated from both non-infected and infected erythrocytes in the form of ghosts were analysed. In general, the phospholipid classes remained unaffected, while the phosphatidylcholine (PC) molecular species composition showed differences after testosterone treatment. In infected erythrocytes, there was a decrease in 16:0/20:4-PC and 18:0/20:4-PC and an increase in 16:0/18:2(16:0/20:3)-PC. The decrease of 16:0/20:4-PC was exclusively confined to parasites. The rise in 16:0/18:2(16:0/20:3)-PC and the diminution of 18:0/20:4-PC occurred in the erythrocyte membrane of both infected ghosts and non-infected ghosts as well as in the blood plasma. It is suggested that these changes occur primarily in the plasma thereby influencing the erythrocyte membranes. The decrease in 16:0/20:4-PC supports the view of the independence of the parasite from the biosynthetic lipid pathways of its host cell.

Testosterone-induced diminution of two peptides in spleen cells from testosterone-immunosuppressed B10 mice

High-performance liquid chromatography (HPLC) is used to detect testosterone (T)-sensitive peptides in spleen cells isolated from female C57BL/10 mice immunosuppressed against Plasmodium chabaudi malaria by T treatment. Two peaks with retention times of about 25 min and 34 min, respectively, were identified to be diminished by about 52% and 47%, respectively, in spleen cells from T-treated mice compared to those from untreated mice. Amino acid sequencing revealed that the 24 min peak consisted of the dipeptide Met-Phe and the 34 min peak contained a degradative fragment of the alpha-chain of hemoglobin. Our data suggest that the immunosuppressive T treatment of B10 mice induces a perturbation of erythrophagocytosis in spleens.

Testosterone-induced susceptibility to Plasmodium chabaudi malaria: variant protein expression in functionally changed splenic non-T cells

This study investigates the effects of the male sex hormone, testosterone (Te), on self-healing of Plasmodium chabaudi malaria as well as on protein expression and functional properties of total spleen cells and splenic T cells in females of the mouse strain C57BL/10. About 90% of the B10 females survive a challenge with 10(6) P. chabaudi-infected erythrocytes. The percentage of self-healers, however, is reduced to about 60%, 40%, and 0% after pretreatment with Te for 1, 2, and 3 weeks, respectively. The progressive loss of the capability of self-healing is correlated with an increasing expression of five proteins in splenic non-T cells as revealed by two-dimensional fluorography after metabolic labelling of total spleen cells and T cells with [35S]methionine. These have molecular masses (isoelectric points) of about 10 kDa (pI 5.7), 14 kDa (pI 6.3), 14 kDa (pI 6.4), 38 kDa (pI 6.5), and 46 kDa (pI 5.5), respectively. Splenic non-T cells from mice treated with Te for 3 weeks have gained an increased capability to stimulate the concanavalin A-induced proliferative response of T cells. Te induces the changes in functional properties and protein expression of splenic non-T cells only in vivo and not in vitro. This suggests that the changes in splenic non-T cells as well as the prevention of self-healing P. chabaudi malaria are not directly induced by Te but rather indirectly, i.e. by a Te metabolite and/or Te-induced factor(s).

Distinct lipid compositions of parasite and host cell plasma membranes from Plasmodium chabaudi-infected erythrocytes

Mouse erythrocytes infected with early or late trophozoites of the malaria parasite Plasmodium chabaudi were fractionated into free parasites and host cell plasma membranes, and both fractions were analyzed for cholesterol content and the composition of phospholipids and total fatty acids. The major results are: (i) parasites contain only a very low level of cholesterol which is about one-tenth of that of host cell plasma membranes. (ii) Parasites also contain less sphingomyelin and phosphatidylserine as well as more phosphatidylcholine than host cell plasma membranes. (iii) Parasites contain less 18:0 and 18:1 and more 18:2 and 20:4 fatty acids than host cell plasma membranes. (iv) During intraerythrocytic growth of parasites from early to late trophozoites, the relative proportions of cholesterol and phospholipids remain largely unchanged in both parasites and host cell plasma membranes. However, significant changes occur in the fatty composition of both compartments. There is an increase in the 20:4 and a decrease in the 18:0 and 18:1 fatty acids. (v) Plasma membranes of infected and non-infected erythrocytes exhibit about the same cholesterol content and phospholipid composition, but differ in the total fatty acid composition. Our data suggest the existence of distinct mechanisms controlling the different lipid compositions of parasites and host cell plasma membranes in whole Plasmodium chabaudi-infected erythrocytes during intraerythrocytic development of parasites, though both compartments are known to depend on the supply of various lipids from the host.