Bestimmung von deoxynivalenol mittels LC - MS/MS (Tandem Massenspektrometrie)

A sensitive and selective method using high-performance liquid chromatography in combination with atmospheric pressure chemical ionization tandem mass spetrometry (LC-APCI-MS/MS) has been developed for the determination of Deoxynivalenol (DON) in trace levels. The extract was purified with a MultiSep? column followed by the Vicam? DON immunoaffinity column. Quantification is based on an external standard method using positive Multiple Reaction Monitoring (MRM). The limit of detection was 5 μg/kg with a signal to noise ratio of 3:1.     

Laboratory experiments on factors affecting the activity of Gammarus pseudolimnaeus Bousfield

Factors such as current, light, food, substrate and time of year were found to influence the activity of specimens of Gammarus pseudolimnaeus maintained in stream tanks in the laboratory. Although there was seasonal variation, levels of diurnal and nocturnal activity were generally much higher when there was no current than when the water was running. Diurnal periodicity occurred but was not as pronounced as had been indicated in the field studies of previous workers. Although there was activity during the day, nocturnal levels were higher especially in specimens collected during the summer. When there was no current, and the lights were left on for 24 h, peak activity occurred at precisely the times when the lights normally would have been off. This strongly suggests that there is an endogenous component in the activity. The nocturnal activity showed a bigeminus pattern, and there was a seasonal change, with the general activity at its highest levels in summer. Activity was significantly greater during daylight both with and without current when there was no substrate present in the tanks. The behaviour of Gammarus appears to be complex and greatly influenced by combinations of the various factors.     

Functional changes in human leukemic cell line HL-60. A model for myeloid differentiation

Polar solvents induce terminal differentiation in the human promyelocytic leukemia cell line HL-60. The present studies describe the functional changes that accompany the morphologic progression from promyelocytes to bands and poly-morphonuclear leukocytes (PMN) over 9 d of culture in 1.3 percent dimethylsulfoxide (DMSO). As the HL-60 cells mature, the rate of O(2-) production increase 18-fold, with a progressive shortening of the lag time required for activation. Hexosemonophosphate shunt activity rises concomitantly. Ingestin of paraffin oil droplets opsonized with complement or Ig increases 10-fold over 9 d in DMSO. Latex ingestion per cell by each morphologic type does not change significantly, but total latex ingestion by groups of cells increases with the rise in the proportion of mature cells with greater ingestion capacities. Degranulation, as measured by release of β-glucuronidase, lysozyme, and peroxidase, reaches maximum after 3-6 d in DMSO, then declines. HL-60 cells contain no detectable lactoferrin, suggesting that their secondary granules are absent or defective. However, they kill staphylococci by day 6 in DMSO. Morphologically immature cells (days 1-3 in DMSO) are capable of O(2-) generation, hexosemonophosphate shunt activity, ingestion, degranulation, and bacterial killing. Maximal performance of each function by cells incubated in DMSO for longer periods of time is 50-100 percent that of normal PMN. DMSO- induced differentiation of HL-60 cells is a promising model for myeloid development.     

Photosynthetic Response to Water Stress in Phaseolus vulgaris

Water stressed Phaseolus vulgaris L. plants were monitored to detect the relationships between net photosynthesis, transpiration, boundary layer plus stomatal resistance, mesophyll resistance, CO₂ compensation point, ribulose, 1,5-diphosphate carboxylase activity and leaf water potential. At full expansion, the first trifoliate leaves of greenhouse grown bean plants were subjected to water stress by withholding irrigation. Gas exchange and enzyme activity of the central trifoliolate leaflets were monitored as leaf water potential decreased. Although increased stomatal resistance appeared to be the primary causal factor of reduced net photosynthesis, increased mesophyll resistance and decreased ribulose 1,5-diphosphate carboxylase activity further documented the role of non-stomatal factors.     

Transport of Nitrate and Calcium into Legume Root Nodules

Nitrate transport into nodulated plants of soybean (Glycinemax), cowpea (Vigna unguiculata) and faba bean (Vicia faba)was investigated. Nitrate entering the root system of soybeandid not pass out of the vascular system into nodular tissuesin detectable quantities. On the other hand, nitrate could passfrom soil through the outer surface of nodules but did not penetratethe infected tissue. Similarly, nitrate was restricted to corticaltissues of cowpea and faba bean. Thus, nitrate cannot inhibitnitrogen fixation as a result of reduction to nitrite by nitratereductase within the bacteroid zone. These results are, however,consistent with an effect of nitrate on an oxygen diffusionresistance located in the nodule cortex. Unlike nitrate, measurable quantities of ⁴⁵calcium were transportedvia the xylem into infected and cortical tissues of soybeannodules: it also passed from the soil into the free space ofthe nodule cortex. Key words: Nitrate, legume nodules, calcium     

Computing approximate standard errors for genetic parameters derived from random regression models fitted by average information REML

Approximate standard errors (ASE) of variance components for random regression coefficients are calculated from the average information matrix obtained in a residual maximum likelihood procedure. Linear combinations of those coefficients define variance components for the additive genetic variance at given points of the trajectory. Therefore, ASE of these components and heritabilities derived from them can be calculated. In our example, the ASE were larger near the ends of the trajectory.     

The Cysts of Blastocrithidia triatomae Cerisola et al., 19711

ABSTRACT. Flagellar cysts of Blastocrithidia triatomae form from active flagellates by diminution in size. The pellicular microtubules disappear. The inner layer of the cell membrane thickens progressively as the organism shrinks. The fully formed cyst has an electrondense layer that corresponds to the outer layer of the unit membrane. An electron-lucent layer is approximately twice the thickness of the middle layer of the unit membrane. Inside that is a 92 nm layer that may represent the cytoplasm. The nuclear content is in the form of whorled bundles of 10–15 nm fibrils. The kinetoplast was not seen in electron micrographs of cysts.     

Varying Kinetoplast Ultrastructure in Two Subspecies of Herpetomonas muscarum (Leidy)*

SYNOPSIS. The kinetoplast nucleoid of Herpetomonas muscarum muscarum is a disk-shaped mass of filaments with sharply delimited anterior and posterior margins. The kinetoplast nucleoid of Herpetomonas muscarum ingenoplastis is elongate, tapered, and made up of long, helically arranged filaments. Possible explanations of these structures on the basis of work by others on isolated kinetoplast DNA are given. The double flagellum of Herpetomonas is seen by electron microscope to be two complete flagella in close contact but with no visible connection to each other.