Phenotype frequencies of vitamin D binding protein (Gc) and of posttransferrin-2 (Ptf-2) in Belgian cattle breeds*

The vitamin D binding protein (Gc) and posttransferrin-2 (Ptf-2) phenotypes have been determined in a number of Belgian cattle breeds. A very slow migrating variant of the Gc protein — Gc C — has been found in White and Red East Flemish breed. This variant was absent from the other breeds studied. This slow variant was identified as a vitamin D binding protein by autoradiography. The Gc C protein was shown to be controlled by a codominant autosomal allele Gc C at the Gclocus. The Gc C protein is probably identical with a fraction previously described in buffalo and an Italian cattle breed. The allele frequencies for the Gc and Pft-2 systems are reported for several Belgian breeds of cattle.     

Tunicamycin-resistant mutants of Bacillus amyloliquefaciens are deficient in amylase, protease and penicillinase synthesis and have altered sensitivity to antibiotics and autolysis

Mutants of Bacillus amyloliquefaciens resistant to at least 10 micrograms/ml of tunicamycin were isolated and shown to be pleiotropic. The mutants were more resistant to streptomycin, chloramphenicol, kanamycin and neomycin than was the parent strain but less resistant to penicillin G and tetracycline. They were more autolytic, presumably due to an altered cell wall. The mutants produced reduced levels of amylase, penicillinase and both metal and serine protease besides having an enhanced sporulation frequency and being more motile.     

Estimate of mean tissue O2 consumption at onset of exercise in males

A mathematical model has been developed that permitted the calculation of the flow-weighted mean tissue O2 consumption (VO2T) at the onset of a step increase in work rate. From breath-by-breath measurements of alveolar O2 consumption (VO2A) and cardiac output (Q) by impedance cardiography and assumptions about the site of depletion of O2 stores, the rate of change in O2 stores (VO2s) was determined. The sum of VO2A + VO2s = VO2T. Six very fit males performed six repetitions of each of two step increases in work rate. STlo was a transition from rest to 100-W cycling; SThi was a transition from 100- to 200-W cycling. For each work rate transition, the responses of VO2A and Q were averaged over the six repetitions of each subject and the model was solved to yield VO2T. The responses of VO2A, VO2T, and Q after the increase in work rate were fit with a monoexponential function. This function included a time constant and time delay, the sum of which gave the mean response time (MRT). In the STlo test, the MRT of VO2A (24.9 +/- 1.1 s, mean +/- SE) was longer than that of VO2T (15.3 +/- 1.3 s) and of Q (16.5 +/- 6.5 s) (P less than 0.05). The MRT of VO2T and Q did not differ significantly. Also for SThi, the MRT of VO2A (34.4 +/- 3.3 s) was significantly longer than that of VO2T (30.0 +/- 3.4 s) (P less than 0.05). The MRT of VO2T and Q (30.3 +/- 5.5 s) were not significantly different at this work rate either.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of polypeptide synthesis initiation by a change of Mg++ concentration in wheat germ cell-free systems

Polypeptide synthesis programmed by poly(U) and globin mRNA has been studied in cell-free extracts from wheat germ. A two-step reaction with a preincubation at high Mg⁺⁺ levels followed by a second step carried out after a shift to a low Mg⁺⁺ concentration and the addition of labeled amino acids is described. Under these conditions the initiation of polyphenylalanine synthesis can be blocked without affecting the elongation of polypeptide chains. This procedure allows the selective inhibition of polypeptide synthesis initiation without using any drug or antibiotic.