Phosphorylation in vivo of the P light chain of myosin in rabbit fast and slow skeletal muscles.

The P light chain of myosin is partially phosphorylated in resting slow and fast twitch skeletal muscles of the rabbit in vivo. The extent of P light-chain phosphorylation increases in both muscles on stimulation. Rabbit slow-twitch muscles contain two forms of the P light chain that migrate with the same electrophoretic mobilities as the two forms of P light chain in rabbit ventricular muscle. The rate of phosphorylation of the P light chain in slow-twitch muscle is slower than its rate of phosphorylation in fast-twitch muscles during tetanus. The rate of P light-chain dephosphorylation is slow after tetanic contraction of fast-twitch muscles in vivo. The time course of dephosphorylation does not correlate with the decline of post-tetanic potentiation of peak twitch tension in rabbit fast-twitch muscles. The frequency of stimulation is an important factor in determining the extent of P light-chain phosphorylation in fast- and slow-twitch muscles.     

Fetal mortality at the time of chorionic villi sampling

Summary To estimate the background fetal loss rates among women who might be candidates for chorionic villi sampling (CVS) for prenatal diagnosis, we examined the frequency of spontaneous abortion and of non-viable fetuses in two groups of women thought to be pregnant at 8–12 weeks' gestation. Among 1519 women over 35 years given an appointment for amniocentesis 1978–1981, 9.8% had a spontaneous abortion prior to 16 weeks' gestation. For those under observation before week 12, the loss rate by 16 weeks was 15.3%. Among all 190 candidates for elective termination of pregnancy between 6 and 12 weeks' gestation, 12.6% were found to have a non-viable fetus at the scheduled date of abortion. The frequency of non-viability was 14% among those seen before week 12. The data suggest that the background loss rate between the time of CVS and the time of amniocentesis is approximately 1–2% and is unlikely to be higher than 9%. Until randomized clinical trials of the procedure are completed we will not know how much, if at all, the loss rate associated with CVS is increased above this background. Nevertheless, knowledge of these background risk estimates may be useful in counseling women considering participating in trials of CVS.     

On the reactivities of the tryptophan residues of human alpha-lactalbumin to 2-hydroxy-5-nitrobenzyl bromide.

The reaction of human alpha-lactalbumin with the tryptophan reagent 2-hydroxy-5-nitrobenzyl bromide has been studied. This protein has 3 tryptophan residues (Trp-60, Trp-104 and Trp-118) all of which are accessible to the reagent at pH 2.7 or 7. Trp-60 of human alpha-lactalbumin is much more reactive than Trp-60 of bovine alpha-lactalbumin (Barman, T. E. (1972) Biochim. Biophys. Acta 257, 297-313). As with bovine alpha-lactalbumin, at pH 2.7, 2-hydroxy-5-nitrobenzyl bromide is specific for tryptophan but at pH 7 His-32 also reacts. When treated with the tryptophan reagent, both alpha-lactalbumins lose their specifier protein activities in the lactose synthase (UDPgalactose:D-glucose 4-beta-galactosyltransferase, EC 2.4.1.22) reaction.     

Phosphorylation of rabbit cardiac-muscle troponin I by phosphorylase kinase. The effect of adrenaline.

1. Incubation of rabbit cardiac-muscle troponin I with phosphorylase b kinase leads to the incorporation of .07-1.2 mol of Pi/mol. 2. The major site of phosphorylation is a serine residue at position 72. 3. Lesser amounts of phosphate are incorporated into threonine-138, threonine-162 and serine 20. 4. Serine-20 is the only site that contains a significant amount of phosphate before incubation with phosphorylase b kinase. 5. Unlike the situation with serine-20, the extent of phosphorylation of serine-72 and threonine-138 in the perfused rabbit heart does not change when the heart is exposed to adrenaline (4 microM).     

The binding of calmodulin to myelin basic protein and histone H2B.

1. A calmodulin-binding protein of apparent mol.wt. 19 000 has been purified from chicken gizzard. Similar proteins have been isolated from bovine uterus, rabbit skeletal muscle and rabbit liver. 2. These proteins migrated as an equimolar complex with bovine brain calmodulin on electroporesis on polyacrylamide gels in the presence of Ca2+ and 6M-urea. The complex was dissociated in the presence of EGTA. 2. The chicken gizzard calmodulin-binding protein has been shown to be identical with chicken erythrocyte histone H2B on the basis of partial amino acid sequence determination. 4. The calmodulin-binding proteins of apparent mol.wt. 22 000 isolated previously from bovine brain [Grand & Perry (1979) Biochem. J. 183, 285-295] has been shown, on the basis of partial amino-acid-sequence determination, to be identical with myelin basic protein. 5. The activation of bovine brain phosphodiesterase by calmodulin is inhibited by excess bovine uterus calmodulin-binding protein (histone H2B). 6. The phosphorylation of myelin basic protein by phosphorylase kinase is partially inhibited, whereas the phosphorylation of uterus calmodulin-binding protein (histone H2B) is unaffected by calmodulin or troponin C. 7. The subcellular distribution of myelin basic protein and calmodulin suggests that the two proteins do not exist as a complex in vivo.     

Effects of chronic administration of antipsychotic drugs on GABA and other amino acids in the mesolimbic area of rat brain.

Albino rats were injected once daily with chlorpromazine (20 mg/kg) or haloperidol (3 mg/kg) for 100 days, and were sacrificed 24 hours or 35 days after the last injection. Brains were frozen rapidly in liquid nitrogen, after which the mesolimbic area (containing nucleus accumbens and olfactory tubercle) and striatum were dissected from each frozen brain. Amino acids were quantitated in the mesolimbic area, and GAD enzyme activity was measured in the striatum. Chronic administration of chlorpromazine and haloperidol did not alter brain GABA content or GAD activity in the treated rats, as compared to saline-injected controls, either 1 or 35 days after injections ended. However, a significant elevation of aspartate content and reduction of glycine content was found after chronic administration of haloperidol. These data suggest that alterations which may be found in the GABA system in autopsied brain from psychotic patients do not result from previous antipsychotic drug therapy.     

BIOCHEMICAL EFFECTS IN MAN and RAT OF THREE DRUGS WHICH CAN INCREASE BRAIN GABA CONTENT

Abstract— Brain amino acids were measured in rats given aminooxyacetic acid (AOAA) by mouth, and in rats given sodium dipropylacetate (DPA) both orally and by intraperitoneal injection. Brain GABA content was significantly elevated by AOAA doses of 10mg/kg/day, but not by 5mg/kg/day. Approximately 4 times as much AOAA is required by mouth as by parenteral injection to raise brain GABA content in the rat. DPA (400mg/kg) increased brain GABA and lowered brain aspartate content significantly 1 h after a single injection. However, DPA given orally (350 mg/kg/day) produced no alterations of any amino acids in rat brain.
Amino acids were measured in plasma and urine from patients treated orally with isonicotinic acid hydrazide (INH) or DPA, and from a volunteer who took AOAA. INH (10–21 mg/kg/day) increased concentrations of β -alanine and ornithine in plasma, as well as urinary excretion of β -alanine. DPA had no such effect. AOAA in oral doses ranging from 1.25 to 5.0 mg/kg/day increased plasma concentrations of β -alanine, ornithine, β -aminoisobutyric acid, proline and hydroxyproline, and produced massive urinary excretion of β -alanine, β -aminoisobutyric acid, and taurine.
Both INH and AOAA, given in doses practical for human use, inhibit the transamination of β -alanine and ornithine in liver, and may also inhibit the transamination of GABA in brain. In addition, AOAA interferes with the catabolism of β -aminoisobutyric acid, proline, and hydroxyproline. AOAA, in the lowest dose employed, appeared more effective than INH as an inhibitor of GABA aminotransferase in man, and might therefore be useful in the treatment of neurological diseases in which brain GABA is deficient.     

Effect of growth substrate on thermal death of thermophilic bacteria.

The heat sensitivity of gram-negative, hydrocarbon-utilizing thermophilic bacteria was altered by a change in growth substrate. Thermophilic strains CC-6, BI-1, and LEH-1, grown with acetate or n-heptadecane as the carbon source, had a higher survival rate when incubated 5 degrees C above their maximum growth temperature than cells of the same organism after growth on glucose or glycerol. There was a correlation between the growth substrated, heat resistance, and the ratios of cellular n-hexadecanoic acid/branched hexadecanoic acid and n-heptadecanoic acid/branched heptadecanoic acid. The bacterial cells that were more heat resistant had ratios of straight-chain/branched-chain fatty acids above 1.0, whereas the heat-sensitive cells had ratios below 0.6.     

SEM analysis of amphibian mesodermal migration

Summary At the end of gastrulation, the lateral mesoderm of amphibian embryos migrates ventrally between the ectoderm and the endoderm. The present study is an examination of the morphology of the leading cells of the mesodermal sheet and of the substratum over which they move (the inner surface of the ectoderm). The cells of the leading edge of the mesoderm are generally round, with very short and narrow flattened projections in the forward direction. These projections do not have a ruffled morphology, regardless of whether fixation is carried out before or after the ectoderm and mesoderm are dissected away from the endoderm. The inner surface of the ectoderm is covered with fine (450–500A) filamentous extracellular material and the ectoderm cells sometimes extend cytoplasmic processes (approx. 0.1 wide) onto the leading surface of the mesoderm or onto adjacent ectoderm cells. These studies indicate that the morphology of cell migration in amphibians is closer to that seen inFundulus than to that characteristic of chick or mammalian cells.This paper is dedicated to the memory of Mac V. Edds, Jr., who warmly encouraged the developmental biologists of the Pioneer Valley