The protective effect of dietary fish oil on murine lupus

Dietary marine lipids markedly reduce the severity of glomerulonephritis and its associated mortality in inbred strains of mice developing autoimmune disease, a model for human systemic lupus erythematosus. We report here the influence of varying the dose of menhaden oil and the timing of its administration on the mortality of female (NZB x NZW) F1 mice. After ingesting 25 wt% menhaden oil (MO) for periods of 1.5 weeks to 12 months, there was a stable content of tissue n-3 fatty acids, with total n-3 fatty acids of 28% and 35% in spleen and liver, respectively. The extent of protection from mortality was dependent on the dose of MO with marked protection at doses of 11 to 25%, marginal protection at 5.5% and no protection at 2.5% MO. Delay in the institution of MO until ages 5 or 7 months still resulted in large reductions of mortality. Conversely, institution of a MO diet from 6 weeks until ages 5 to 7 months followed by a change to beef tallow resulted in little protection. Serum levels of 4 cyclooxygenase products were reduced ranging from 26 to 76% in mice fed MO diets, compared to mice fed beef tallow, based on radioimmunoassay. The degree of reduction of mortality on different doses of MO was correlated best with tissue levels of C22:5, and levels of C20:5 and C22:6 were similar at high and low doses of MO, suggesting that levels of 22:5 may be related to the protective effects of marine lipids on autoimmune disease.     

Enhanced enzymatic hydrolysis of lignocellulosic biomass pretreated by low-pressure steam autohydrolysis

Summary The use of low-pressure steam autohydrolysis in the pretreatment of corn stover and hybrid poplar has been assessed. In terms of yield of prehydrolyzed solids, minimal by-product formation and extent of subsequent enzymatic saccharification, the results of low-pressure steam pretreatment were found to be as good as or better than those reported for more severe pretreatment processes. Almost complete saccharification of the cellulose in the prehydrolyzed biomass solids was obtained within 24h with a commercial cellulase preparation — Celluclast. The presence of grinding elements (glass beads) during the enzymatic hydrolysis was found to increase the extent of saccharification by 40% to 50% over controls without any grinding elements.     

Unexpected segregation ratios from male-linked translocations in the Mediterranean fruitfly,Ceratitis capitata (Diptera: Tephritidae)

Three male-linked translocations were isolated in the Mediterranean fruitfly, Ceratitis capitata (Wiedemann) which showed sex linkage for an autosomal pupal colour marker, white pupa (wp). The wild type allele (wp ^–) was translocated to the male-determining chromosome. Males emerge from wild type pupae (brown) and females from white pupac. These lines will be used to develop an automatic sexing system.During maintenance of these lines in large populations it was noted that in two of them there was a significant distortion in the expected 1: 1 segregation ratio for pupal colour and excess white pupae were produced. However, adults did not emerge from a large proportion of these pupae. Using known numbers of 1st instar larvae from the three lines, the distortion was further studied and the effect confirmed. To account for this pupal colour segregation distortion it was assumed that certain duplication/deficiency zygotes survive to the late pupal stage. These zygotes have a deficiency for the wild type allele, therefore the normally recessive mutant allele wp could be expressed (pseudo-dominance).The overall fitness of the three lines was calculated, and their suitability for the genetic sexing of large populations is discussed.     

Inheritance of UMP synthase in dairy cattle

The inheritance of uridine-5'-monophosphate (UMP) synthase in dairy cattle was consistent with a two-allele, single-autosomal-locus model. Two phenotypes were associated with different levels of the enzyme in bovine erythrocytes. The predominant phenotype (assumed normal) had twice the concentration of UMP synthase as the second phenotype (deficient). A one-to-one correspondence between enzyme level and genotype identified one homozygote as normal, the heterozygote as deficient, and the other homozygote as unobserved. Three alternative hypotheses were rejected. The deficiency as homozygous recessive was rejected because 20 matings between assumed normal males and deficient females resulted in 10 normal and 10 deficient offspring. The hypothesis that the deficiency was homozygous dominant was rejected because the 95 percent confidence interval about the observed gene frequency, 0.0024 to 0.0146, did not contain the estimated gene frequency for equilibrium between an average 10(-5) mutation rate and selection against the deficiency as homozygous dominant. Analyses of female relatives implicated one bull as deficient (96 percent probability), as he had, independently, 2 deficient daughters, 5 deficient granddaughters from untested dams, and 3 deficient great-granddaughters from untested ancestors. The hypothesis that the deficiency was sex-linked was rejected because 3 of 9 tested sons of the putative deficient bull were deficient. Calf mortality is expected in 25 percent of matings between deficient animals.     

A model of the smooth pursuit eye movement system

Human, horizontal, smooth-pursuit eye movements were recorded by the search coil method in response to Rashbass step-ramp stimuli of 5 to 30 deg/s. Eye velocity records were analyzed by measuring features such as the time, velocity and acceleration of the point of peak acceleration, the time and velocity of the peaks and troughs of ringing and steady-state velocity. These values were averaged and mean responses reconstructed. Three normal subjects were studied and their responses averaged. All showed a peak acceleration-velocity saturation. All had ringing frequencies near 3.8 Hz and the mean steady-state gain was 0.95.It is argued that a single, linear forward path with any transfer function G(s) and a 100 ms delay (latency) cannot simultaneously simulate the initial rise of acceleration and ring at 3.8 Hz based on a Bode analysis. Also such a simple negative feedback model cannot have a steady-state gain greater than 1.0; a situation that occurs frequently experimentally. L.R. Young's model, which employs internal positive feedback to eliminate the built-in unity negative feedback, was felt necessary to resolve this problem and a modification of that model is proposed which simulates the data base. Acceleration saturation is achieved by borrowing the idea of the local feedback model for saccades so that one nonlinearity can account for the acceleration-velocity saturation: the main sequence for pursuit. Motor plasticity or motor learning, recently demonstrated for pursuit, is also incorporated and simulated.It was noticed that the offset of pursuit did not show the ringing seen in the onset so this was quantified in one subject. Offset velocity could be characterized by a single exponential with a time constant of about 90 ms. This observation suggests that fixation is not pursuit at zero velocity and that the pursuit system is turned on when needed and off during fixation.     

Superoxide production by polymorphonuclear leukocytes

Summary Phagocytosis by polymorphonuclear leukocytes triggers a burst of oxidative metabolism resulting in hydrogen peroxide and superoxide production, and these active oxygen species function in the killing of microorganisms. A new cytochemical technique, based on a manganese dependent diaminobenzidine oxidation, has been developed to detect superoxide in these cells. It has been shown that superoxide generation is associated with the plasma membrane in cells activated by particulate (zymosan) and nonparticulate (phorbol myristate acetate) stimuli. This membraned activity is maintained during invagination such that reduced oxygen is generated within the endocytic vacuoles. Reaction product is absent from unstimulated cells; additionally, formation of precipitate is blocked by omission of Mn⁺⁺, low temperature, glutaraldehyde prefixation, and the presence of superoxide dismutase in the incubation medium.In honour of Prof. P. van Duijn     

Isolation and characterization of prolyl hydroxylase from Chlamydomonas reinhardii

Prolyl hydroxylase, which is responsible for the hydroxylation of peptidyl proline residues, has been isolated and purified from the green alga Chlamydomonas reinhardii. The enzyme, which appears to be loosely associated with microsomal membranes, was released into solution by sonication in the presence of detergent. Purification was achieved by ion-exchange chromatography followed by affinity chromatography using the immobilized substrate poly-L-proline. Apart from its differing substrate specificity the enzyme appears to possess similar molecular characteristics to prolyl hydroxylase isolated from animal tissues: the active enzyme is a tetramer of about 240–250 kDa and nonidentical monomers of 65 and 60 kDa. The monomers are capsule shaped having a dimension of 12×7 nm.Abbreviations Da dalton - DEAE diethylaminoethyl - DTT dithiothreitol - Hepes 4-(2-hydroxymethyl)-1-piperazine ethanesulfonic acid - -KGA -ketoglutarate - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulfate     

Isolation of a copper complex and its rate of appearance in roots of Mimulus guttatus

A Cu-complex was isolated from the roots of copper-tolerant Mimulus guttatus. The elution volume of the complex determined by gel permeation chromatography was similar to that of rat-liver cadmium thionein. The complex was heat stable, had a relatively high ratio of absorbance at 254 nm: 280 nm and incorporated ³⁵S. The complex, purified using a combination of gel permeation chromatography and anion-exchange chromatography, contained more glutamine/glutamic acid and glycine residues than mammalian metallothioneins. The amount of the complex in roots increased after 5 h growth in a solution containing 16 M Cu. Induction was preceded by an increase in the concentrations in root tissue of unknown compounds containing sulphur which may serve as precursors. The availability of these compounds appeared to regulate the rate of synthesis of this Cu-complex.Abbreviations CuBP copper-binding protein - HPLC highperformance liquid chromatography - MT metallothionein - Th thionein - Tris 2-amino-2-(hydroxymethyl)1-3-propanediol