The use of bulk segregant analysis to identify a RAPD marker linked to leaf rust resistance in barley.

An F2 population from a cross between barley accession Q21861 and the Australian barley variety 'Galleon' was used to develop RAPD markers for resistance to barley leaf rust (Puccinia hordei). Resistant and susceptible DNA bulks were constructed following the classification of F2 plants by leaf rust infection type. Bulked segregant analysis was then used to identify a 2.7-kb marker, designated OU022700 and located approximately 12cM from RphQ, a leaf rust resistance gene in Q21861. The marker was generated by PCR with the oligonucleotide primer OPU-02 (Operon). Infection types of F3 progeny were used to confirm assignment of F2 genotypes. OU022700 was shown, retrospectively, to be useful in the identification of individual F2 plants that had been originally misclassified as having susceptible infection types. Both the RAPD marker and RphQ will be potentially useful in the development of new barley cultivars.

Protein and methionine hydroxy analog for lactating cows.

A 2 X 2 factorial experiment (protein 12.5 and 15.5; methionine hydroxy analog 0 and .125% dry matter) included 144 cows for one complete lactation, distributed over seven locations. Rations were formulated to the desired protein, methionine analog, and constant amounts of fiber 17%, sulfur .225%, calcium .6%, phosphorus .4%, and salt .5%. Treatment effects were not apparent for dry matter intake, daily milk and fat-corrected milk production, conversion of energy, and body weight changes. Conversion of dietary crude protein into milk protein was 34.5% for the low and 25.8% for the high protein ration. Methionine analon (0% = 2.54; .125% = 1.90). Effect of methionine analog was most apparent at low protein as 0 analog cows produced 247 kg fat, required 2.9 services/contraception, and had 156 days open whereas cows on other treatments (.125% analog and/or high protein) produced 264 kg fat, required 1.8 to 2.2 services/conception, and had 124 to 134 days open. Methionine analog response is discussed in relation to tuminal and postruminal effects as well as the interrelation with protein and energy.

Differential pulmonary residual volume determinations with radioactive xenon.

A radioactive xenon inhalation procedure was used to determine differential residual volumes (right lung vs. left lung) in 28 normal subjects (6 of whom smoked approximately 1 package of cigarettes per day). The average right lung residual volume represented 54% of the total residual volume, whereas the average left lung residual volumerepresented 46% of the total. In addition, all of the subjects were studied by a standard helium dilution technique and found to have total lung residual comparable to the total lung residual volume as determined by the xenon technique. There was no statistical difference between the data obtained from cigarette smokers vs. nonsmokers. The noninvasive nature of the xenon technique makes this a useful procedure in determining differential residual volumes.

Comparative hemodynamic consequences of inflation hold, PEEP, and interrupted PEEP: an experimental study in normal dogs.

Cardiac output and airway, intrathoracic, arterial, pulmonary artery, left atrial, and central venous pressures were studied in 8 mongrel dogs. They were anesthetized and ventilated with (1) inflation hold of various duration, (2) continuous positive end-expiratory pressure and one breath off). The results indicate a minimal decrease in cardiac output (of approximately 5 per cent) with inflation hold. Diminished cardiac output was noted with increasing levels of continuous PEEP. The severity of the decrease in cardiac output wasproportional to the airway pressure. The higher levels (20 cm H2O) OF PEEP were associated with profound decreases. Utilization of a technique of interrupted PEEP substantially reduced the adverse hemodynamic effects in the dog.