A hexaploid triticale from Mexico and local cultivars of wheat, rye and barley, each at five levels of fertilizer nitrogen (0, 35, 70, 105 and 140 kg N/ha) with four replications, were grown in a field experiment at Mintaro, South Australia. A visually discernible response to nitrogen fertilizer by all four genotypes from an early stage was confirmed by quantitative sampling at tiliering, anthesis and maturity. Responses in plant dry weight to 105 kg N/ha were maintained until anthesis but grain yield responses were significant only at 35 kg N/ha. Total dry matter production responses at maturity to more than 35 kg N/ha were small. Numbers of tillers and heads were increased by nitrogen additions up to 140 and 105 kg N/ha, respectively, and plant height measurements showed general increases to 70 kg N/ha with significant lodging at higher nitrogen levels in both rye and triticale. For all genotypes, thousand grain weight decreased with increasing level of nitrogen supply while grain and straw nitrogen increased up to levels of 140 and 105 kg N/ha, respectively. Nitrogen supply had little effect on maturity, plants at 0 and 140 kg N/ha reaching anthesis less than a day apart. The lack of a significant nitrogen x genotype interaction in nearly all the data suggests that the triticale does not differ in its nitrogen nutrition from the traditional cereals. Triticale consistently outyielded the other cereals in total dry matter production followed by the rye, wheat and barley in that order. Grain yield was highest in the wheat and least in the rye, the latter also being the least responsive to nitrogen. The advantage of the triticale lay in its high grain protein and lysine content combined with good yield.
The thiophores studied exhibit a tight coupling between sulphur and calcium uptake and storage, and apparently store these elements as inorganic salts within the cells of their foliage. Thiophore behaviour is a constitutive trait shared by closely related Acacia but is not highly prevalent within, nor exclusive to, xerophytes. Several of the newly identified thiophores occupy coastal or riparian habitats, suggesting that the evolutionary and ecophysiological explanations for this trait do not lie solely in adaptation to arid conditions or gypsiferous soils.
Nine advanced lines of triticale were grown at seven sites in South Australia. None of them differed significantly from Warimba wheat in nitrogen, ash or crude fat content, their neutral detergent fibre contents were 6-28% higher than wheat, and eight of them had significantly higher total lysine content than wheat. Two triticale lines, T507 (Coorong) and X75-832P, were compared with Warimba wheat in a sloperatio assay with rats. Despite the higher lysine content of these two triticale diets, the rats failed to increase growth rate, and no significant differences were observed between test diets.
The activities of two key enzymes, methionine adenosyltransferase (EC 2.5.1.6) and cystathionine y-lyase (EC 4.4.1.1), involved in the metabolism of methionine to cyst(e)ine have been studied in the liver, heart, kidney medulla, kidney cortex, pancreas, duodenal wall, spleen and skeletal muscle in the neonatallarnb, unweaned lamb, adult sheep, pre-ruminant calf, ruminant steer and adult goat, and for comparative purposes in the adult rat.Methionine adenosyltransferase was widely distributed in the tissues of the ruminant species examined, with specific activities in the order of 10 2 nmol S-adenosylmethionine formed per milligram protein per 30 min. Greatest activities were found in liver, kidney, spleen and duodenal wall in adult ruminants, and also in skeletal muscle in pre-ruminant lambs and calves. Hepatic methionine adenosyltransferase activity declined with age in both sheep and cattle.Cystathionine y-lyase activity was not demonstrable in skeletal muscle or heart in any of the species examined. Greatest activities (in the order of 10 nmol cystathionine degraded per milligram protein per 30 min) were found in liver, kidney and pancreas for all species. Neonatal lamb tissues had the highest activities. In sheep specific activities in liver, pancreas, kidney cortex and spleen declined with age.
The rate of oxidization of the carboxyl and methyl carbons of (I4C]methionine to CO2 by homogenates of liver, kidney cortex, pancreas, muscle and small intestinal mucosa was studied in two breeds of sheep (Merino and Poll Dorset Horn) at three ages (2 weeks, 3 months, 4 years). Sodium a-keto-,),-methiolbutyrate (0·4 mM) stimulated production of CO2 from the carboxyl carbon of methionine, but not from the methyl carbon. Sodium pyruvate did not affect the recovery of CO2 from either carboxyl or methyl of methionine. Sodium formate (15 mM) suppressed the conversion of the methyl carbon of methionine to CO2 by liver and kidney homogenates to 4 and 50%, respectively, of control values, but did not affect the percentage of carboxyl carbon of methionine recovered in CO2 with either tissue. With addition of S-methyl-L-cysteine (40 mM) and 3-methylthiopropionate (10 mM) the percentage of methyl and carboxyl carbons recovered in CO2 was reduced to about 20% of control values in homogenates of both tissues.Activity per gram oftissue was higher in liver and kidney cortex than in pancreas, intestinal mucosa, or muscle, with no significant differences due to breed (Merino or Poll Dorset Horn) or sex (ewe, ram or wether) of sheep. Conversion of both the carboxyl and methyl carbons to CO2 by liver was significantly lower in 2-week-old lambs than in older animals (P <0·0 I). The activity of other tissues was not markedly affected by age.Results are discussed in relation to evidence of alternative pathways of methionine catabolism, and capacities of the tissues of the sheep to catabolize methionine by alternative pathways.
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