1. Two Pseudomonas strains isolated from soil metabolized 2,4-dichlorophenoxyacetate (2,4-D) as sole carbon source in mineral salts liquid medium. 2. 2,4-Dichlorophenoxyacetate cultures of Pseudomonas I (Smith, 1954) contained 2,4-dichlorophenol, 2-chlorophenol, 3,5-dichlorocatechol and alpha-chloromuconate, the last as a major metabolite. 3. Dechlorination at the 4(p)-position of the aromatic ring must therefore take place at some stages before ring fission. 4. Pseudomonas N.C.I.B. 9340 (Gaunt, 1962) cultures metabolizing 2,4-dichlorophenoxyacetate contained 2,4-dichloro-6-hydroxyphenoxyacetate, 2,4-dichlorophenol, 3,5-dichlorocatechol and an unstable compound, probably alphagamma-dichloromuconate. 5. Cell-free extracts of the latter organism grown in 2,4-dichlorophenoxyacetate cultures contained an oxygenase that converted 3,5-dichlorocatechol into alphagamma-dichloromuconate, a chlorolactonase that in the presence of Mn(2+) ions converted the dichloromuconate into gamma-carboxymethylene-alpha-chloro-Delta(alphabeta)-butenolide, and a delactonizing enzyme that gave alpha-chloromaleylacetate from this lactone. 6. Pathways of metabolism of 2,4-dichlorophenoxyacetate are discussed.

1. A pseudomonad capable of utilizing 4-chlorophenoxyacetate (CPA) as sole source of organic carbon was isolated from soil. 2. The organism was grown in liquid culture and the following compounds were isolated and identified in culture extracts: 4-chloro-2-hydroxyphenoxyacetate, 4-chlorocatechol, beta-chloromuconate probably the cis-trans isomer and gamma-carboxymethylene-Delta(alphabeta)-butenolide. 3. Cells grown on 4-chlorophenoxyacetate were able to metabolize 4-chloro-2-hydroxyphenoxyacetate, 4-chlorocatechol and gamma-carboxymethylene-Delta(alphabeta)-butenolide without a lag period. They were not adapted to 4-chlorophenol, or to either culture isolated or synthetic beta-chloromuconate, possibly because of stereospecificity towards the cis-cis isomer. 4. On the basis of isolation and induction evidence, the following metabolic pathway is proposed for the breakdown of 4-chlorophenoxyacetate by this organism: 4-chlorophenoxyacetate --> 4-chloro-2-hydroxyphenoxyacetate --> 4-chlorocatechol --> cis-cis-beta-chloromuconate --> gamma-carboxymethylene-Delta(alphabeta)-butenolide --> maleylacetate and fumarylacetate --> fumarate and acetate.

Circulating concentrations of 25-hydroxyvitamin D2 (25OHD2) and 25-hydroxyvitamin D3 (25OHD3) provide, respectively, a measure of the contributions of the diet and sunshine to the overall vitamin D status. These indices were measured in grazing sheep over a 16 month period which included their first pregnancy. Seasonal fluctuations in 25OHD3 concentrations were very marked, demonstrating both the dominance of photobiosynthesis as a source of vitamin D in the summer and also the lack of an effective storage mechanism. The concentration of 25OHD2 was subject to much smaller fluctuations, but when young grass was being consumed it was significantly lower than when mature grass or hay was fed. Supplementation in winter maintained circulating concentrations at a satisfactory level and may be a wise precaution in practice.

An outbreak of rickets in sheep under a year old (hoggs) appeared clinically as stiffness and rotation of the carpal joints. Histological studies confirmed the diagnosis and biochemical analyses of blood demonstrated a primary vitamin D deficiency.

Eight mature female sheep were offered a ration which maintained body weight constant during a 20-week period. During the final 10 weeks a comparison was made in each animal of the pattern of equilibration and urinary losses of tritiated water during 8 h after dosing by four different routes. These were intravenous, intraperitoneal, intraruminal and a combination of the intraperitoneal and intraruminal routes. Tritiated water spaces were calculated from (a) the 8-h plasma specific activity and (6) by extrapolation to zero time of the plasma specific activities during the 7 days after injection. At the end of the experiment the fat and water contents of the bodies of the sheep were determined directly.Complete equilibration of tritiated water between plasma and rumen water was not achieved in all animals 8 h after intravenous or intraperitoneal injection but was when the rumen was primed by the combination of intraperitoneal and intraruminal dosing. After intraruminal dosing equilibration was not achieved in any animal within 8 h of dosing.Urinary losses of marker were lower after intraruminal dosing but otherwise averaged 4-5 % of the dose/1 urine. This was equivalent to 0-3-6-7 % of the dose for individual sheep.Errors resulting from incomplete equilibration and urinary loss of marker did not influence the efficiency of prediction of total body water from tritiated water space.The multiple correlation coefficient relating body fat with empty body weight and its water content was very high (r = 0-99). Errors introduced into this relationship by the inclusion of gut water in the prediction equations were apparently of a similar magnitude to those resulting from the errors in the estimation of tritiated water space.The extrapolation method for the determination of tritiated water space was shown to have the same accuracy as equilibration techniques under these controlled dietary conditions.