Ratio Of Tri Research Articles

Distribution and Structural Variation of Nonstarch Polysaccharides in Milling Fractions of Hull‐less Barley with Variable Amylose Content

ABSTRACTThree hull‐less barley genotypes containing starches with variable amylose content (23.8% normal, 4.3% waxy, 41.8% high‐amylose barley) were pearled to 10% and then roller‐milled to produce pearling by‐products (PBP), flour, and fiber‐rich fractions (FRF). PBP were enriched in arabinoxylans, protein, and ash and contained small amounts of starch and β‐glucans. FRF were considerably enriched in β‐glucans and arabinoxylans. The solubility of β‐glucans was higher in PBP than in FRF. The solubility of arabinoxylans was higher in FRF than in PBP. Small amounts of arabinogalactans detected in barley were concentrated in the outer portion of the barley kernel. The content and solubility of nonstarch polysaccharides (NSP) in various milling fractions was also dependent on the type of barley. To obtain more detailed information about the content and molecular structure of NSP, each milling fraction was sequentially extracted with water, alkaline [Ba(OH)2], again with water, and finally with NaOH. These extractions resulted in four sub‐fractions: WE, Ba(OH)2, Ba(OH)2/H2O, and NaOH. β‐Glucans and arabinoxylans exhibited structural heterogeneity derived from differences in their location within the kernel as well as from the genetic origin of barley. The WE arabinoxylans from FRF and flour had a substantially lower degree of branching than those from PBP. The WE arabinoxylans from FRF of high‐amylose and normal barley contained more unsubstituted Xylp residues but fewer doubly‐substituted and singly‐substituted Xylp at O‐2 than their counterparts from PBP. The WE arabinoxylans from FRF of waxy barley had a relatively high content of doubly‐substituted, but very few singly‐substituted Xylp residues. In all three barley genotypes, the ratio of tri‐ to tetrasaccharides in β‐glucans from PBP was higher than from flour and FRF. Substantial differences in the molecular weight of NSP in different milling fractions were also observed.

The micronucleus assay in human lymphocytes after high radiation doses (5–15 Gy)

Individuals can be exposed to high doses (more than 5 Gy) during radiation accidents. It is, of course, helpful to the physician to have biological indicators also for such high doses. The problem with most cytogenetic indicators is, that the response levels off at doses starting around 5–7 Gy of low LET radiation and that the dose-response curve even declines after doses exceeding about 10 Gy. Thus, it may be difficult to decide, whether the dose was, for example, 8 or 14 Gy. We studied how the micronucleus assay can be used to give information also in the high dose range. It turned out that micronucleus frequency itself cannot be used for the estimation of doses exceeding about 5–7 Gy. There are, however, at least three other endpoints that can be determined in the cytochalasin B assay that can assist the decision in the high dose range: (1) the number of mononucleated cells; (2) the ratio of tri- to tetranucleated cells; (3) the average micronucleus frequency in micronucleus positive binucleated cells.

ChemInform Abstract: Relationships Between Structural Features, Molecular Weight and Rheological Properties of Cereal β-D-Glucans

Publisher Summary Although cereal β-D-glucans exhibit similar C13-NMR spectra, their structural features are different from each other as evident by the ratios of tri- and tetrasaccharides released from lichenase hydrolysis (4, 3, and 2 for wheat, barley and oat p-D-glucans, respectively). This chapter demonstrates the correlation between the structural features, molecular weight, and some physical properties including solubility of freeze-dried samples and gel forming aptitude. Rheologically, cereal β-D-glucans behave similarly to random coil polysaccharides; however, some β-D-glucans can form gels under certain conditions, which is not observed for other random-coil polysaccharides including galactomannans. The gelling ability and insolubility of freeze-dried cereal β-D-glucans followed the order of wheat > barley > oat; this trend corresponds with the ratio of tri- and tetrasaccharides of cereal β-D-glucans. In addition to the structural features, molecular weight also plays an important role in the conformation of cereal β-D-glucans in aqueous systems. The results indicate that lower molecular weight β-D-glucan is easier to form a gel than larger molecules.

98/01938 Oleananes in oils and sediments: Evidence of marine influence during early diagenesis? : Murray, A. P. et al. Geochim. Cosmochim. Acta, 1997, 61, (6), 1261–1276

Eight oil and condensate samples and four samples of possible source rocks from the Yamal peninsula, northernmost West Siberia, have been characterized geochemically in order to determine source rocks and their maturity level. The high content of C29 steranes (m/z = 217) in extracts combined with geological data indicate nearshore marine and continental depositional environments for Cretaceous argillites. Jurassic source rocks, with a predominance of C27 steranes and Pr/Ph ratios of 2.4–2.6, have been deposited in the deeper marine basin and contain oil-prone type II kerogen. A number of parameters 20S/20S + 20R, ββ/ββ + αα steranes (m/z = 217), 22S/22S + 22R, hopane/hopane + moretane (m/z = 191), ratios of tri- and monoaromatic steroids (m/z = 231, m/z = 253), and methylphenanthrene ratios show an increase in maturity with depth, from immature Cretaceous source rocks to moderately mature Jurassic sources (Bazhenov and Tyumen Formations). Oil-oil and oil-source rock correlations based on genetic parameters and maturity indicators have demonstrated that fluids found in Jurassic and Cretaceous reservoirs, including heavy biodegraded oil from the Cenomanian, belong to a single family and could be derived jointly from the Bazhenov (J3) and Tyumen (J1–2) Formations. The origin of naphthenic condensate found at shallow depth is still controversial. Although earlier work has suggested that biodegradation has been a dominant factor in the formation of naphthenic condensates, their formation from Cretaceous source rocks with type III kerogen could also be possible.

Structure and physicochemical properties of barley non-starch polysaccharides — I. Water-extractable β-glucans and arabinoxylans

Water-soluble non-starch polysaccharides were extracted from a Canadian malting barley (cv. Harrington) by sequential treatment with water at 40 °C (WE40) and 65 °C (WE65). The yields were 1.4 and 1.3% (w/w), respectively, of the dry barley grist. The WE40 extract was composed of 82.5% glucose, 8.9% xylose, and 7.0% arabiose residues, whereas WE65 contained 93.3% Glc, 3.3% Xyl, and 2.5% Ara. Only minute amounts of mannose and galactose residues were found in either fraction. Both extracts were further fractionated by stepwise (NH 4) 2SO 4 precipitation into several polysaccharide populations. Subfractions from both extracts, obtained up to 45% saturation with (NH 4) 2SO 4, contained mostly β-glucans, whereas subfractions precipitated at increasing saturation levels of (NH 4) 2SO 4 (45–100%) contained progressively more arabinoxylans and less β-glucans. Compared to WE40, the WE65 extract was enriched in β-glucan populations with higher molecular size, higher limiting viscosity values, and higher content of β-(1 → 4) linkages. The ratio of tri-/ tetrasaccharide oligomers was also higher in β-glucans extracted at 65 °C than those extracted at 40 °C. Arabinoxylans in both extracts, WE40 and WE65, were highly substituted and contained large proportions of doubly substituted xylose residues.

Geochemical characteristics of oils and source rocks in the Yamal peninsula, West Siberia, Russia

Eight oil and condensate samples and four samples of possible source rocks from the Yamal peninsula, northernmost West Siberia, have been characterized geochemically in order to determine source rocks and their maturity level. The high content of C 29 steranes ( m/ z = 217) in extracts combined with geological data indicate nearshore marine and continental depositional environments for Cretaceous argillites. Jurassic source rocks, with a predominance of C 27 steranes and Pr/Ph ratios of 2.4–2.6, have been deposited in the deeper marine basin and contain oil-prone type II kerogen. A number of parameters 20 S/20 S + 20 R, ββ/ ββ + αα steranes ( m/ z = 217), 22 S/22 S + 22 R, hopane/hopane + moretane ( m/ z = 191), ratios of tri- and monoaromatic steroids ( m/ z = 231, m/ z = 253), and methylphenanthrene ratios show an increase in maturity with depth, from immature Cretaceous source rocks to moderately mature Jurassic sources (Bazhenov and Tyumen Formations). Oil-oil and oil-source rock correlations based on genetic parameters and maturity indicators have demonstrated that fluids found in Jurassic and Cretaceous reservoirs, including heavy biodegraded oil from the Cenomanian, belong to a single family and could be derived jointly from the Bazhenov (J 3) and Tyumen (J 1–2) Formations. The origin of naphthenic condensate found at shallow depth is still controversial. Although earlier work has suggested that biodegradation has been a dominant factor in the formation of naphthenic condensates, their formation from Cretaceous source rocks with type III kerogen could also be possible.

The respiratory response of juvenile mud crabs, Rhithropanopeus harrisii to variations in salinity and following short-term exposure to halowax 1099®, a polychlorinated naphthalene (PCN)

Juvenile mud crabs Rhithropanopeus harrisii were exposed for five days to Halowax 1099, a polychlorinated naphthalene (approximately 1:1 ratio of tri- and tetrachlorinated isomers). Exposure concentrations were 0, 20, 50 or 100 μg/litre. The exposure salinity was 15%. At the end of the exposure period, respiratory rates of the crabs were determined at 15% S. The respiratory rates were also determined for control and exposed animals which were osmotically shocked by a move from 15% S to either 5 or 25% S immediately before respirometry. Exposure to PCNs always caused the mean respiratory rates of juvenile crabs to increase over control values. The respiratory response of crabs to PCN exposure was similar at the steady-state salinity (15% S) and after hyperosmotic shock (25% S). However, the mean rate for animals exposed to PCNs and given a hyposmotic shock was significantly higher than that for controls and for PCN-exposed animals at the other two salinities. Since hyperosmotic regulation of body fluids is most active at low salinities in this species, we suggest that the PCNs interfere with hyperosmotic regulation and reduce the efficiency of metabolic compensation for hyposmotic shock. The higher energetic cost of acclimation to transient reductions in salinity would be potentially detrimental to wild populations in impacted areas.

Variations of rat thyroid activity during exposure to high environmental temperature (34 degrees C). Relation between hypothalamic pituitary and thyroid hormone levels.

Changes in thyroid activity and variations in the hypthalamo-pituitary-thyroid hormone levels were examined in rats exposed to heat (34 degrees C)for3 weeks. Thyroid activity evaluated histologically (epithelium/colloid ratio, nuclear size) by radioiodine exploration (24 hrs 125 I uptake, ratio of mono- to di-125 iodotyrosines - MIT/DIT, ratio of tri- to tetra-125 iodothyronines-T3/T4, and plasma 125I-T4 and assay of plasma T4, evolves in a triphasic manner. 1.a depression phase between day 0 and day 2.5. 2. a rebound of thyroid activity between day 2.5 and day 9.3 a stabilization of thyroid parameters from day 9 to day 24. These results indicate adaptation of thyroid function to heat after 3 weeks. In phase i, plasma TSH )MeKenzie bioassay) fell to undectable levels concurrent with a 50% decrease in hypothalamic TRH (in vitro assay). Plasma TSH peaked on day 4.5, fell on day 9.5 and returned progressively to initial levels. Hypothalamic TRH returned to initial levels after 6.5 days. The rapid and simultaneous decrease in hypothalamic TRH, plasma TSH, plasma T4 and thyroid activity by the 36th hour of heat exposure (34 degrees C) suggests initiation at the hypothalamic level. In the secound phase, the rebound in thyroid activity is presumably due to the peak in circulating TSH in ralation to the marked decrease in plasma T4. The oscillations of phase 2 and the stabilization of all the thyroid parameters in phase 3 may be the reflection of an apparent discrepancy remains between a low plasma T4 and a normal or subnormal plasma TSH. A modification in the "set point" for the control of TSH secretion is discussed.