An association between a lymphocyte antigen in sheep and the response to vaccination against the parasite Trichostrongylus colubriformis

Lymphocyte antigens were tested in sheep which had been selected for responsiveness to vaccination against the intestinal nematode Trichostrongylus colubriformis. These sheep had been bred in an assortative mating programme which produced offspring designated as either “high responders” or “low responders”, with highly heritable resistance or susceptibility.Ovine lymphocyte antigen (OLA) typing antisera were obtained from parous ewes in the course of matings which produced the high and low responder flocks. A particular antigen (SY1) was found to be present in high frequency on the lymphocytes of high responder (72·2%) and in lower frequency (21·9%) on the lymphocytes of low responder rams. In ewes, the frequency for high responders was 65·7% and for low responders it was 33·5%. A similar association between the SY1 antigen and low faecal egg count was found in random-bred sheep which had been vaccinated with irradiated larvae and challenged with normal larvae. The conclusion was drawn that this lymphocyte antigen was likely to be part of the sheep major histocompatibility complex which influenced the immune response of sheep to vaccination against the parasite.     

Development of sporeless/low sporing strains of Pleurotus through mutation

Summary The sporophores of Pleurotus are gymnocarpous and continuously release spores in the atmosphere causing respiratory allergies like hay fever and farmer’s lung disease among workers. The allergy is caused by the antigens present on the walls of the spores. Apart from this, during commercial production, these spores settle on the fruit bodies, germinate and form a velvety film which gives an unpleasant appearance to the mushrooms. The spores emitted may include new genotypes likely to attack wood or trees. Spore allergy is one of the most important limiting factors for the large scale cultivation of this species. Different approaches are being adopted at IIHR for the production of commercial sporeless/low-sporing strains of Pleurotus to alleviate the spore allergy problem. Attempts were made during the present investigation to produce sporeless or low-sporing mutants through u.v. mutation. Mutation of the mycelium did not yield the desired results. Mutation of the spores of Pleurotus sajor-caju yielded an extremely low-sporing mutant after 75 min exposure. The character has been found to be stable for more than 10 generations of subculturing.     

Antagonistic and synergistic interactions between aluminum and manganese on growth of Vigna unguiculata at low ionic strength

Concentrations of soluble aluminum (Al) and manganese (Mn) frequently reach phytotoxic levels in acid soils. While dose response relationships for these metals are well documented, the effects of combined exposure have received less attention. We have examined the effect of combinations of Al and Mn on growth and metal accumulation in Vigna unguiculata (L.) Walp. grown in solution culture under conditions of low ionic strength (conductivities typically < 100 µS cm⁻¹). The nature of interaction between these metals varied with the specific physiological response, the part of the plant investigated, and the relative amount of stress imposed. Analysis of growth data provided evidence for amelioration of metal toxicity (antagonistic effects), although this effect was dose dependent. Analysis of metal content data provided evidence for antagonistic and synergistic (exacerbation of toxicity) effects, again depending on dose. Analysis of foliar symptoms also provided evidence for antagonisms and synergisms, with the nature of the response dependent on the specific physiological response and specific plant part investigated. In contrast with previous reports, evidence for antagonistic, synergistic, and multiplicative effects on growth, metal uptake, and expression of foliar symptoms have been obtained under physiologically and environmentally relevant conditions. These results suggest a more detailed analysis of the potential for interactions between metals in the environment is required.     

Lysine Succinylation of VBS Contributes to Sclerotia Development and Aflatoxin Biosynthesis in Aspergillus flavus

Aspergillus flavus is a common saprophytic and pathogenic fungus, and its secondary metabolic pathways are one of the most highly characterized owing to its aflatoxin (AF) metabolite affecting global economic crops and human health. Different natural environments can cause significant variations in AF synthesis. Succinylation was recently identified as one of the most critical regulatory post-translational modifications affecting metabolic pathways. It is primarily reported in human cells and bacteria with few studies on fungi. Proteomic quantification of lysine succinylation (Ksuc) exploring its potential involvement in secondary metabolism regulation (including AF production) has not been performed under natural conditions in A. flavus. In this study, a quantification method was performed based on tandem mass tag labeling and antibody-based affinity enrichment of succinylated peptides via high accuracy nano-liquid chromatography with tandem mass spectrometry to explore the succinylation mechanism affecting the pathogenicity of naturally isolated A. flavus strains with varying toxin production. Altogether, 1240 Ksuc sites in 768 proteins were identified with 1103 sites in 685 proteins quantified. Comparing succinylated protein levels between high and low AF-producing A. flavus strains, bioinformatics analysis indicated that most succinylated proteins located in the AF biosynthetic pathway were downregulated, which directly affected AF synthesis. Versicolorin B synthase is a key catalytic enzyme for heterochrome B synthesis during AF synthesis. Site-directed mutagenesis and biochemical studies revealed that versicolorin B synthase succinylation is an important regulatory mechanism affecting sclerotia development and AF biosynthesis in A. flavus. In summary, our quantitative study of the lysine succinylome in high/low AF-producing strains revealed the role of Ksuc in regulating AF biosynthesis. We revealed novel insights into the metabolism of AF biosynthesis using naturally isolated A. flavus strains and identified a rich source of metabolism-related enzymes regulated by succinylation.     

Low night temperatures have a differential effect on the diurnal cycling of gene expression in cold–sensitive and tolerant tomatoes*

Abstract. Comparisons were made between the changes in mRNA levels induced by low night temperatures in the cold–sensitive tomato and two altitudinal ecotypes of the wild species L. hirsutum. Changes in mRNA levels were detected by resolving in vitro translation products of poly(A)⁺ RNA by 2-D PAGE. The treatment was applied by first growing plants in a thermoperiod of 25/18°C and then switching to 25/6°C. All tomatoes displayed a diurnal cycling in which a set of mRNAs accumulated at the end of the 18°C nights, whereas another accumulated at the end of the 25°C days. The accumulation of night specific mRNAs was inhibited by 6°C nights in the cold sensitive tomatoes while that of the tolerant one was only marginally affected. All tomatoes showed a similar reduction in the apparent turnover rate of the day specific mRNAs during the 6°C nights. Finally, low night temperatures induced the accumulation of six to eight mRNAs in all genotypes. This number increased by 15 in L. esculentum after the seventh night and are likely involved in stress response rather than acclimation/tolerance. The tomato is proposed as a genetic model to discriminate genes involved in acclimation/tolerance from those involved in stress response.     

Experiments on the effects of a continuous 16.7 Hz magnetic field on melatonin secretion, core body temperature, and heart rates in humans.

The present study investigated the hypothesis that a strong extremely low frequency magnetic field partially suppresses the synthesis of melatonin and subsequently elevates the core body temperature. Seven healthy young men (16-22 years) took part in a control and in an exposure session. Three men experienced first the control and then the exposure session, four men experienced the sessions in reverse order. Control sessions were performed as constant routines, where the participants spent 24 hour periods continuously in bed while air temperature was 18 degrees C, illumination less than 30 lux, and the sound pressure level 50 dBA. The exposure sessions differed from that protocol only between 6 pm and 2 am when a strong extremely low frequency magnetic field was continuously applied (16.7 Hz, 0.2 mT). Assuming that the participants were unable to perceive the field consciously, they were blind against the actual condition. Salivary melatonin levels were determined hourly; body core temperatures and heart rates were registered continuously throughout. Neither of these parameters revealed alterations that can be related to the influence of the magnetic field. The present results, taken together with other investigations using that particular field, lead to the hypothesis that the effects most likely, occur, only after repetitive exposures to intermittent fields.     

THE COMBINED EFFECTS OF LOW TEMPERATURE AND SO2+NO2 POLLUTION ON THE NEW SEASON'S GROWTH AND WATER RELATIONS OF PICEA SITCHENSIS

Picea sitchensis (Bong.) Carr. seedlings were exposed to SO₂, NO₂ and SO₂+ NO₂ during dormancy in controlled environments, and were taken to night temperatures of 4, 0, −5, −10 and −15 °C in a freezer. Conditions in the freezer were carefully monitored during the low–temperature treatments. In two experiments, different photoenvironments and temperature regimes were imposed prior to the cold treatments, and different effects were observed. In the first, only limited frost hardiness was achieved and night temperatures of −15 °C were lethal. Temperatures of −5 and − 10 °C led to poor survival of lateral buds, particularly in plants exposed to 45 ppb SO₂. The poor bud break in plants exposed to SO₂ and to − 5 °C resulted in a loss of the effectiveness of this temperature as a chill requirement. Pressure-volume analysis showed that the shoots of plants exposed to NO₂ had greater elasticity (lower elastic moduli, e), so that loss of turgor occurred at lower relative water contents. In contrast, a hardening period (2 weeks in night/day temperatures of 3/10 °C and 8 h days at 50 μmol m⁻² s⁻¹ PAR) gave decreased elasticity and lower solute potentials of spruce shoots. In the second experiment, exposure to 30 ppb SO₂ and SO₂+ NO₂ led to slight, but consistent, increases in frost injury to the needles of plants frozen to − 5 and − 10 °C. The results suggest that the main interaction of low temperatures and winter pollutants may be on bud survival rather than on needle damage, but that effects are subtle, only occurring with certain combinations of pollutant dose and cold treatment.