Agglutinability of cattle red cells. 4. The effect of antiglobulin in comparison with treatment by pronase.

The average titre scores varied from zero to 24.7 for the cattle red cells (CRC) from different MZ pairs. These CRC were sensitized with different blood-typing reagents and were titre-tested against the double dilution series of an anti-bovine gamma-globulin serum. A significant negative correlation (r = - 0.82; P less than 0.001) was found between the degree of agglutinability and the amount of neuraminic acid of the surface component of CRC cleaved by pronase. After pronase treatment of the CRC it could be demonstrated that (1) the activity of the V and E'3 blood factors became destroyed; (2) three new specific receptors became evolved; (3) the degree of 'direct' agglutinability due to the A2, O3, W, S2 and Z anti-sera did not parallel with the titre scores obtained in the anti-globulin tests.     

Agglutinability of cattle red cells. 1. Agglutination by lectins of enzyme-treated red cells

Pronase-treated cattle red cells (CRC) from different monozygous (MZ) twin pairs could be classified as weakly (titre 1: 2, 1: 4) or strongly (titre 1: 1024, 1: 4096) agglutinable when Phytohemagglutinin-M (Phy-M) was used as agglutinin. In the presence of concavalin-A (Con-A), the CRC from different MZ pairs treated with pronase, A-chymotrypsin or trypsin showed a gradation from low (titre 1: 32) to high (titre 1: 256 000) agglutinability. The trypsin-treated CRC which had A₁, A₂ blood factors usually had a titre of 1: 8000 or higher with Con-A. Both the intact CRC and the CRC treated with proteolytic enzymes were capable of absorbing the Phy-M or Con-A lectins.     

Agglutinability of cattle red cells. 2. Agglutination by isologous and heterologous sera of enzyme-treated red cells

Neuraminidase treatment made cattle red cells (CRC) agglutinable by the agglutinins of the different heterologous but not of the homologous sera. These agglutinins were, however, absorbed by both the nauraminidase-treated and the intact CRC.
Proteolytic treatment made CRC agglutinable also by the normal cattle, isoimmune and autologous sera. Agglutination titres of the CRC ranged from 1: 2 to 1: 256, but the variation between CRC from members of monozygous (MZ) pairs was not greater than ± 2 agglutination score units the range of experimental error.
Treatment with trypsin made the A₁, A₂ factors more emergent on the surface of CRC for agglutination by anti-A₂, while pronase treatment had a similar effect upon agglutination of Z-positive cells by anti-Z.     

Alterations in reactivity of the blood factors of cattle red cells after pronase treatment

Pronase treatment of cattle red cells produced various effects: (a) an increase in reactivity of the J factor and evolution of a specific cryptoantigen; (b) decrease in the A-B, G₂, K, I₂ O₂, O₃, P, Q, T_1; Y₂, A, B', E'₂, E'₃, I', K', O'-L'-V-L and M, factors, but (c) no change in the specifity or in the titre of the remaining 16 different blood factors. Most of the pronase-affectable blood factors were destroyed in a rather narrow but characteristic range of pronase treatment intensities. However, at like intensities, variations were demonstrable due to the fact that the blood factor occurred (a) in red cells from different individuals, and (b) in different phenogroups or subgroups of the B locus.     

CONCANAVALIN A-INDUCED AGGLUTINATION AND BINDING OF CON A TO THE DIFFERENTIATING CELLS OF DICTYOSTELIUM DISCOIDEUM

Changes in agglutinability of Dictyostelium discoideum cells with Concanavalin A (Con A) during the course of development were investigated. The agglutinability of the cells was assayed under conditions where no spontaneous cell agglutination occurred. It was found that there was a progressive decrease in Con A-induced agglutinability during development: a decrease to half from exponentially growing cells to preaggregation cells, and to sixth in disaggregated slug cells. Pronase-BAL treatment of preaggregation cells did not enhance their agglutinability with Con A. The amounts of sites available for binding Con A were determined with preaggregation and slug cells. Cells were incubated at 4°C and in the presence of NaN₃ to avoid possible endocytosis of Con A. No significant differences in numbers of Con A-binding sites per unit area of cell surface was detected among preaggregation cells, those treated with pronase and BAL and cells disaggregated from slugs by similar treatment. It was thus concluded that the decrease in Con A-induced agglutinability during development is not attributable to changes in the numbers of Con A-binding sites.     

Concanavalin A Receptors Associated with Rat Brain Synaptic Junctions Are High Mannose-Type Oligosaccharides

Abstract: Glycoproteins were isolated from a rat brain synaptic junction fraction by affinity chromatography on Concanavalin A-agarose. The isolated glycoproteins were digested with pronase and radiolabeled with ¹²⁵I-Bolton Hunter reagent, and ¹²⁵I-Concanavalin A-binding glycopeptides were isolated by chromatography on Concanavalin A-agarose. Treatment of the ¹²⁵I-Concanavalin A-binding glycopeptides with either α-mannosidase or endo-β- N -acetylglucosaminidase-C₁₁ abolished their interaction with Concanavalin A. The pronase digest was reacted with endo-β-N-acetylglucosaminidase-C₁₁ and released oligosaccharides were reduced with NaB³H₄. Following affinity chromatography on Concanavalin A-agarose, Concanavalin A-binding [³H]oligosaccharides were chromatographed on Biogel P₄. Two major oligosaccharides corresponding to standard carbohydrates containing eight and five mannose residues were identified. Treatment of these oligosaccharides with α-mannosidase converted them to smaller saccharides having a mobility on Biogel P₄ columns equal to the standard disaccharide mannose-β-1-4- N '-acetylglucosamine. These results demonstrate that the Concanavalin A receptor activity associated with CNS synaptic junctions resides in asparaginelinked oligosaccharides of the high-mannose type.     

Effect of modification of storage atmosphere on phospholipids and ultrastructure of cauliflower mitochondria

Differences in mitochondrial membrane composition and ultrastructure were studied after storage of cauliflower ( Brassica oleracea , L., Botrytis group) for 5 days at 25°C in air or under controlled atmospheres: 3% O₂, 21% O₂+ 15% CO₂ or 3% O₂+ 15% CO₂. In air, postharvest senescence involved a 20% decrease in mitochondrial phospholipid content. A large reduction in the relative abundance of phosphati-dylcholine (PC) and in the degree of unsaturation of PC and phosphatidyl ethanolamine (PE) was observed. However, the degree of unsaturation increased in cardiolipin (CL). Storage under 3% O₂ did not prevent phospholipid breakdown. Low O₂ prevented the relative decrease in PC observed during storage in air and the loss of linoleic acid from PC, but not from PE. This relative protection offered by the low O₂ atmosphere was lost under 3% O₂+ 15% CO₂. The high CO₂ atmospheres caused twice as much loss in phospholipids as that observed during storage in air. Extensive loss of mitochondrial protein, a marked decrease in phospholipid to protein ratio, and electron micrograph observations suggest structural alterations in the presence of high CO₂.     

Agglutinability of cattle red cells. 3. Conglutination.

Addition of both complement and conglutinin was necessary to conglutinate the cattle red cells (CRC) when they were sensitized by different blood typing reagents. Although the degree of conglutinability of the CRC was influenced by the particular blood factor-reagent combination the average conglutinability (i.e. average titre scores) of CRC from different MZ pairs varied from 1.9 to 16.2. The titres of complement varied from zero to 1:32, while the titres of conglutinin ranged from 1:8 to 1:1024 in the different sera from MZ cattle twins. The variance due to differences in the titre scores between MZ pairs was 82.2% for conglutinin and 68.3% for complement. There was no evident association between the titres of conglutinin and complement.     

δ 13C of CO2 respired in the dark in relation to δ13C of leaf carbohydrates in Phaseolus vulgaris L. under progressive drought

The variations in δ ¹³C in both leaf carbohydrates (starch and sucrose) and CO₂ respired in the dark from the cotyledonary leaves of Phaseolus vulgaris L. were investigated during a progressive drought. As expected, sucrose and starch became heavier (enriched in ¹³C) with decreasing stomatal conductance and decreasing p _i/ p _a during the first half (15 d) of the dehydration cycle. Thereafter, when stomata remained closed and leaf net photosynthesis was near zero, the tendency was reversed: the carbohydrates became lighter (depleted in ¹³C). This may be explained by increased p _i/ p _a but other possible explanations are also discussed. Interestingly, the variations in δ ¹³C of CO₂ respired in the dark were correlated with those of sucrose for both well-watered and dehydrated plants. A linear relationship was obtained between δ ¹³C of CO₂ respired in the dark and sucrose, respired CO₂ always being enriched in ¹³C compared with sucrose by ≈ 6‰. The whole leaf organic matter was depleted in ¹³C compared with leaf carbohydrates by at least 1‰. These results suggest that: (i) a discrimination by ≈ 6‰ occurs during dark respiration processes releasing ¹³C-enriched CO₂; and that (ii) this leads to ¹³C depletion in the remaining leaf material.     

In vitro complementation of Bacillus subtilis and Escherichia coli. 2-oxoglutarate dehydrogenase complex mutants and genetic mapping of B. subtilis citK and citM mutations

Abstract The 2-oxoglutarate dehydrogenase complex of the tricarboxylic acid cycle (TCA) consists of multiple copies of 3 different subenzymes; E₁, E₂ and E₃. The E₃ subenzyme is also a component of the pyruvate dehydrogenase complex. Bacillus subtilis 2-oxoglutarate dehydrogenase mutants were studied. The mutants defective in E₁, E₂ and E₃ subenzyme activity, respectively, could be separated into 3 groups by biochemical complementation analyses. The groups correspond to the citK, citM and citL genes. A B. subtilis subenzyme defect, probably E₁, could be complemented with the corresponding Escherichia coli wild-type subenzyme and vice versa. Mutations in citK and citM are closely linked. The gene order kauA——citK-citM was determined from 3-factor transformation crosses. It is concluded that the gene organization and the subenzyme structure of the 2-oxoglutarate dehydrogenase complex are similar in B. subtilis and E. coli .     

Agglutinability of cattle red cells. 3. Conlutination

Addition of both complement and conglutinin was necessary to conglutinate the cattle red cells (CRC) when they were sensitized by different blood typing reagents. Although the degree of conglutinability of the CRC was influenced by the particular blood factor-reagent combination the average conglutinability (i.e. average titre scores) of CRC from different MZ pairs varied from 1.9 to 16.2.
The titres of complement varied from zero to 1:32, while the litres of conglutinin ranged from 1:8 to 1:1024 in the different sera from MZ cattle twins. The variance due to differences in the titre scores between MZ pairs was 82.2 % for conglutinin and 68.3 % for complement. There was no evident association between the titres of conglutinin and complement.     

Interfering mechanism of sodium bicarbonate on spore germination of Bacillus stearothermophilus

Spore germination of Bacillus stearothermophilus was progressively inhibited as the concentrations of sodium bicarbonate (NaHCO₃) in the germination media increased from 0% to 1·0% (w/v). The inhibitory effect of NaHCO₃ was attributed to the release of HCO⁻₃ and its alkaline properties, each of which played a different role. At low concentrations (< 0·3%), the inhibitory effect of NaHCO₃ was mainly due to bicarbonate. As NaHCO₃ increased from 0·3% to higher concentrations, the effect of HCO⁻₃ reached a plateau while the alkalinating effect became the more dominant inhibitory factor. Fourier transform infrared (FTIR) analysis reveals that sodium bicarbonate reacted with the carboxyl group (1570 cm⁻¹) of some acidic amino-acid residues of protein in the spore, leading to a less orientated structure. A shift of two units towards the longer frequency for carboxyl groups indicates that a stronger interaction was formed between the carboxyl group and the Na⁺ ion. The largest ratio of peak height between the absorbance of carboxylate (1570 cm⁻¹) and of amide II (1546 cm⁻¹) of spores after pretreatment with 0·3% sodium bicarbonate reflects the biggest structural alterations of keratin-like proteins in the spore. The role of NaHCO₃ in enhancing the sporicidal effect of glutaraldehyde is discussed.     

Effects of copper, lead and zinc in soil on egg development and hatching of Folsomia candida

Effects of CaCl₂, CuCl₂, ZnCl₂ and PbCl₂ on development and hatching success of eggs of Folsomia candida (Collembola) were studied under laboratory conditions. Thousands of healthy eggs from synchronized cultures were incubated in soils treated with different concentrations of the metals. Compared with the water control, egg hatch significantly decreased when concentrations of Cu, Pb and Zn reached 400, 1600 and 800 mg/kg dry soil, respectively. Values of EC_{50 (hatching)}, calculated according to the exponential model (with 95% confidence limits in brackets), were 625 (407–875), 2361 (2064–2687) and 1763 (1548–2000) mg/kg dry soils for Cu, Pb and Zn, respectively. When Cu concentration reached 1600 mg/kg dry soil, eggs became green and the percentage of green eggs changed from 5%–20% after incubation for 2 days to 15%–30% after incubation for 4 days. At 3200 mg Cu/kg dry soil, tissues inside eggs were black and shrunken.     

Diagnostic parameters for selecting against novel spruce (Picea abies) decline: IV. Response of photosynthesis and transpiration to SO2+NO2 exposures

The dose- and time-response effects of 3 days of 6 h day-time sequential exposures to NO₂, SO₂ and SO₂+NO₂ of 0.45–1.81 μl l⁻¹ (ppm) SO₂ and 1.50–7.65 μl l⁻¹ NO₂ on photosynthesis, transpiration and dark respiration were examined for nine Carpatho-Ukrainian half-sib families and a population from the GFR ('Westerhof') of Norway spruce [ Piecea abies (L.) Karst.], all in their 5th growing season.
SO₂+NO₂ inhibited photosynthesis and transpiration and stimulated dark respiration more than SO₂ alone. SO₂ and SO₂+NO₂ at the lowest concentrations inhibited night transpiration, but increased it at the highest concentration, the strongest effects being obtained with combined exposures. Photosynthesis of the different half-sib families was affected significantly differently by SO₂+NO₂ exposures. NO₂ alone had no effects.
Sensitivity to transpiration decline correlated negatively with branch density. Height of trees correlated postitively with decline sensitivity in the seed orchard. The distribution of photosynthesis and transpiration sensitivities over all tested half-sib families correlated negatively with the distribution of decline sensitivity of their parents in a rural Danish seed orchard. The relative photosynthesis and transpiration sensitivities may thus serve as diagnostic parameters for selecting against novel spruce decline.     

The presence of oxygen in rumen liquor and its effects on methanogenesis

In situ measurement of O₂ in the rumen liquor of cows, sheep and goats using a membrane-covered O₂ electrode revealed the presence of up to 1630 nmol/l O₂; O₂ became undetectable immediately after feeding of animals. The effects of O₂ on H₂ production and methanogenesis in samples of rumen liquor were investigated using a mass spectrometer fitted with a membrane inlet system. Methanogenesis was totally and irreversibly inhibited after short term exposure (about 10 min) to 5 KPa (0·05 atm) O₂; H₂ production was unaffected. Glucose additions produced rapid transient increases in H₂ levels and increased O₂ uptake.     

LEAF INFECTION OF COTTON BY XANTHOMONAS MALVACEARUM (E.F.SM.) DOWSON

Xanthomonas malvacearum spread more rapidly along vascular tissue than into mesophyll when inoculated to the main veins of susceptible cotton leaves. The extent of spread varied with the concentrations of inocula, tissue age and cotton variety.
Increasing concentrations of inocula accelerated the initial spread of disease.
Bacteria spread more rapidly in young leaves than in old—increasing age greatly decreased disease in the mesophyll. The initial invasion was quicker in young leaves of young plants than in young leaves of old plants.
Three types of behaviour, according to the host's reaction, distinguish Knight's resistance factors: ( a ) where X. malvacearum spread extensively along veins and into mesophyll of plants containing factors B₃ and B₅; ( b ) where it was restricted to the point of inoculation in plants containing B ₄, B₉ and combinations with B _6m; and ( c ) where it spread along veins but not appreciably into mesophyll in varieties containing B ₂ and B ₂ B ₃.
From this and four other different types of tests, factors B ₂ and B ₃ seem to increase mesophyll resistance but only B ₂ gives appreciable vascular resistance. Further, the vascular bundles in varieties with B ₂ seem to be surrounded by an additional 'barrier' which resists X. malvacearum.     

Nitrogen concentration, ammonium/nitrate ratio and NaCl interaction in vegetative and reproductive growth of peanuts

Peanuts ( Arachis hypogaea L. cv. Shulamit) grown with NO₃⁻ and saline water in hydroponics responded positively to addition of nitrogen (N) in their vegetative growth, but not in desert dune sand. In order to clarify these conflicting results, peanut plants were grown in a greenhouse pot experiment with fine calcareous sand. The nutrient solution contained 0 or 50 m M NaCl and 2 or 6 m M N in the form of Ca(NO₃)₂, NH₄NO₃ or (NH₄)₂SO₄. Three replicates were harvested after 48 days (beginning of reproductive stage) and three after 109 days (pod filling). In addition, gynophores were treated with 0, 50, 100, 150 or 200 m M NaCl outside the growth pot to check their sensitivity to salt. Shoot dry weight became greater with increasing NH₄⁺/NO₃⁻ ratio. Increasing the N concentration from 2 to 6 m M did not change shoot dry weight of the NH₄NO₃ or NH₄⁺-fed plants, but caused a reduction in shoot dry weight of NO₃⁻-fed plants. Shoot dry weight was not affected by increasing the NaCl concentration to 50 m M . Salt caused an increase in the number of gynophores per plant and a reduction of the mean pod weight. A NaCl concentration of 100 m M and above reduced gynophore vitality. It is concluded that the salt sensitivity of peanut plants resides mainly in the sensitivity of the reproductive organs.     

PATHOGENICITY OF METARHIZIUM ANISOPLIAE VAR. ACRIDU TO THE DEVEOLPMENTAL STAGES OF BROWN PLANTHOPPER NILAPARVATA LUGENS STÅL AND SOGATELLA FURCIFERA (HORVATH)

Abstract  The susceptibility and virulence of entomopathogenic fungus Metarhizium anisopliae var. acridum to the stages of brown planthopper (BPH), Nilaparvata lugens (Stål) and whitebacked planthopper (WBPH), Sogatella furcifera (Horvath) were investigated under laboratory conditions. Three dosages of M. anisopliae var. acridum ranging from 10.5, 116.3 and 1027.1 conidial/mm² were used in the experiment. The tested stages of host included three developmental stages, young nymphs (1–2 instars), old nymphs (3–5 instars) and adults. It was found that all tested stages of the planthoppers were susceptible to the fungal infection. The degree of virulence LT₅₀ of M. anisopliae var. acridum against young nymphs of N. lugens are >21, 20.82 and 16.55, respectively with the 3 dosages, the LT₅₀ of the fungus against the old nymphs are 17.68, 15.49 and 13.98, respectively with the 3 dosages; the LT₅₀ of the fungus against the adults are 17.10, 12.57 and 9.14 respectively with the 3 dosages. The degree of virulence LT₅₀ of M. anisopliae var. acridum on young nymphs of S. furcifera are >21, 17.29 and 13.13, respectively with the 3 dosages _; the LT₅₀ of the fungus against the old nymphs are 16.94, 15.02 and 13.03, respectively with the 3 dosages; the LT₅₀ of the fungus against the adults are 12.78, 10.16 and 7.64, respectively with the 3 dosages. Adults were more susceptible to M. anisopliae var. acridum infection than their nymphs and the young nymphs were most resistant to the fungal infection. The cumulative mortality of each stage was dosage-dependent. Of all the developmental stages, WBPH was more susceptible than BPH to M. anisopliae var. acridum infection with the same dosages.     

Oxygen requirements of larvae of the smallmouth bass, Micropterus dolomieui Lacépède

Smallmouth bass larvae became highly sensitive to oxygen deficiency on the second day after hatching and continued so to the 10th day. During this period they could not survive exposure to 1 mg O₂ l^–1 for 3 h at 20° C, and many were killed within 1 h. At 2 mg O₂ l^–1 half the larvae survived 3 h at 20° C; at 2.5 mg l^–1 most survived, and at 3.5 mg l^–1 all survived. Resistance to oxygen deficiency was regained by the 11th day, the majority of the larvae withstanding a 3-h exposure at 1 mg O₂ l^–1. At 25° C the effects of low oxygen concentration were intensified. At 3 and 4 mg O₂ l^–1 and 20° C the normally quiescent larvae became very active, even swimming to the surface 5 or 6 cm above the substrate. Increasing the temperature increased this response. Smallmouth larvae were more sensitive than large-mouth bass larvae to oxygen deficiency.     

Combined effect of organic acids and supercritical carbon dioxide treatments against nonpathogenic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium and E. coli O157:H7 in fresh pork

Aims:  To evaluate the effectiveness of organic acids and supercritical carbon dioxide (SC-CO₂) treatments as well as their combined effect for the reduction of nonpathogenic Escherichia coli and three pathogenic bacteria in fresh pork.
Methods and Results:  The different treatment conditions were as follows: (i) treatment with acetic (1%, 2% or 3%) or lactic acid (1%, 2% or 3%) only, (ii) treatment with SC-CO₂ at 12 MPa and 35°C for 30 min only and (iii) treatment with 3% acetic or lactic acid followed by treatment with SC-CO₂. Within the same organic acid concentration, the lactic and acetic acid treatments had similar reductions. For the combined treatment of lactic acid and SC-CO₂, micro-organism levels were maximally reduced, ranging from 2·10 to 2·60 log CFU cm⁻² ( E. coli , 2·58 log CFU cm⁻²; Listeria monocytogenes , 2·60 log CFU cm⁻²; Salmonella typhimurium , 2·33 log CFU cm⁻²; E. coli O157:H7, 2·10 log CFU cm⁻²).
Conclusions:  The results of this study indicate that the combined treatments of SC-CO₂ and organic acids were more effective at destroying foodborne pathogens than the treatments of SC-CO₂ or organic acids alone.
Significance and Impact of the Study:  The combination treatment of SC-CO₂ and organic acids may be useful in the meat industry to help increase microbial safety.