Phosphorylation of 3-hydroxy-3-methylglutaryl coenzyme A reductase by microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase kinase

Microsomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase kinase has been purified to apparent homogeneity by a process involving the following steps: solubilization from microsomes and chromatography on Affi-Gel Blue, phosphocellulose, Bio-Gel A 1.5m, and agarose-hexane-ATP. The apparent M_r of the purified enzyme as judged by gel-filtration chromatography is 205,000 and by sodium dodecyl sulfate-gel electrophoresis is 105,000. Immunoprecipitation of homogeneous reductase phosphorylated by reductase kinase and [γ-³²P]ATP produces a unique band containing ³²P bound to protein which migrates at the same R_f as the reductase subunit. Incubation of ³²P-labeled HMG-CoA reductase with reductase phosphatase results in a time-dependent loss of protein-bound ³²P radioactivity, as well as an increase in enzymic activity. Reductase kinase, when incubated with ATP, undergoes autophosphorylation, and a simultaneous increase in its enzymatic activity is observed. Tryptic treatment of immunoprecipitated, ³²P-labeled HMG-CoA reductase phosphorylated with reductase kinase produces only one ³²P-labeled phosphopeptide with the same R_f as one of the two tryptic phosphopeptides that have been reported in a previous paper. The possible existence of a second microsomal reductase kinase is discussed.     

Postsynaptic alpha adrenoceptors on vascular smooth muscle

A heterogeneous population of alpha adrenoceptors mediates vasoconstriction in the canine saphenous vein (CSV). Studies with isolated strips of venous smooth muscle incubated with selective alpha-adrenoceptor agonists and antagonists revealed that both alpha 1 and alpha 2 adrenoceptors exist independently in this tissue and both subtypes mediate a contractile response. Measurement of contractile responses in reduced or zero external calcium conditions indicates that stimulation of alpha 1 adrenoceptors induces contractions by influx of extracellular calcium and release of calcium from internal stores. In contrast, 45Ca uptake studies suggest that activation of the postsynaptic alpha 2 adrenoceptor produces vasoconstriction dependent only on influx of extracellular calcium. The influx of calcium produced by the selective alpha 2-adrenoceptor agonist BHT-920 is inhibited by calcium entry blockers. Measurements of transmembrane potentials from smooth muscle cells of the CSV suggest that alpha 1-adrenoceptor activation produces depolarization and contraction (electromechanical coupling) whereas alpha 2-adrenoceptor stimulation does not result in concentration-dependent depolarization of the smooth muscle cells (pharmacomechanical coupling).     

Effects of two different experimental situations of hypothyroidism on serum aldosterone concentration and plasma renin in rats

When hypothyroidism is induced surgically in early steps of development in the rat, an increase in serum aldosterone concentration (AC), in absence of changes in plasma renin activity (PRA), is observed. In contrast, in propylthiouracil (PTU) induced hypothyroidism, in adult animals, both AC and PRA decrease. Potassium iodide (KI) or triiodo-L-thyronine (T3) administration to thyroidectomized rats restores AC to normal levels, increasing PRA during the latter treatment. A close relationship between AC and plasma renin concentration (PRC) is observed in these experimental situations. The decrease in urinary aldosterone concentration (ACu), and the relation found between AC/ACu ratio and T3 concentration, suggest that metabolic clearance of aldosterone might be related to peripheric T3 levels in thyroidectomized animals, treated with KI or T3. These observations support the hypothesis, previously reported, which suggests different mechanisms involved in the control of aldosterone and renin release during the two different types of hypothyroidism.     

Possible effect of bromocriptine on the insulin receptor

The administration of 0.00011 mg/g weight/day of bromocriptine (CB154) for 7 days to Wistar rats, improved the peripheral glucose uptake without significant changes in plasma insulin level, during the intravenous glucose tolerance test (0.33 g/kg). The mode of the bromocriptine action on binding of 125I insulin to erythrocyte insulin receptors has been evaluated. The total number of sites was greater with bromocriptine (513.1 +/- 124.1 pM/1,CB154 815.6 +/- 107.9 pM/l) (p less than 0.01). The high affinity/low capacity compound of insulin receptor, in CB154 rats (51.8 +/- 16.8 pM/l) was higher than in normal rats (18.3 +/- 8.9 pM/l) (p less than 0.005). Additional studies indicated that CB154 had no effect on the rate of association and dissociation of 125I insulin from rats erythrocyte insulin receptors. The degradation of insulin or the erythrocyte receptor sites do not change, after the treatment with CB154.     

Female transfer in primates

Intergroup transfer by males is nearly universal among social primates. Furthermore, among the most frequently studied monkeys-savanna baboons and Japanese and rhesus macaques—females typically remain in their natal groups, so troops are composed of related matrilines. These facts strongly support two major theories: (l) that kin selection is a powerful force in patterning sociality (if one is to live in a group, one should prefer a group of one’s relatives); and (2) that the ultimate explanation for intergroup transfer is the avoidance of inbreeding depression (though both sexes would prefer to live with kin, one sex has to disperse to avoid inbreeding and for a variety of reasons the losing sex is generally male). Substantial rates of transfer by females in social species with routine male transfer would cast doubt on both ideas. In fact, evidence reviewed here indicates that female transfer is not unusual and among folivorous primates (e.g., Alouatta,the Colobinae) it seems to be routine. In addition to casting doubt on the demographic significance of inbreeding avoidance and favoring mutualistic and/or game theory interpretations of behavior over nepotistic ones, this finding supports the hypothesis that predator detection is the primary selective pressure favoring sociality for many primates. Finally, while female bonding [sensuWrangham, R. W. (1980), Behaviour75:262–299] among primates appears to be less common than generally believed, the observed correlation between female transfer and morphological adaptations to folivory provides empirical support for Wrangham’s model for the evolution of female-bonded groups.     

Assembly of Bacillus subtilis phage phi29. 1. Mutants in the cistrons coding for the structural proteins.

The effect of mutations in the cistrons coding for the phage structural proteins has been studied by analyzing the phage-related structures accumulated after restrictive infection. Infection with susmutants in cistron 8, lacking both the major head and the fiber protein, does not produce any phage-related structure, suggesting a single route for the assembly of phage phi29; infection with ts mutants in this cistron produces isometric particles. Mutants is cistron 9, coding for the tail protein, TP1, produce DNA-free prolate heads with an internal core; these particles are abortive and contain the head proteins HPO, HP1 and HP3, the upper collar protein NP2 and the nonstructural proteins p7, p15 and p16. Mutants in cistron 10, coding for the upper collar protein, NP2, produce DNA-free isometric heads also with an internal core; they contain the head proteins and the nonstructural protein p7, suggesting that this protein forms the internal core. Mutants in cistrons 11 and 12, coding for the lower collar protein, NP3, and the neck appendages, NP1, respectively, give rise to the formation of DNA-containing normal capsids and DNA-free prolate particles, more rounded at the corners than the normal capsids and with an internal core; the DNA-containing 11-particles are formed by the head proteins and the upper collar protein; the DNA-free 11-particles contain, besides these proteins, the nonstructural protein p7 and a small amount of proteins p15 and 16. The DNA-containing 12-particles have all the normal phage structural proteins except the neck appendages, formed by protein NP1; the DNA-free particles are similar to the DNA-free 11-particles. After restricitive infection mutant sus14(1241) has a delayed lysis phenotype and produces a phage burst higher than normal, after artificial lysis. It produces DNA-containing particles, identical to wild-type phage, which have all the normal phage structural proteins, and DNA-free prolate particles, more rounded at the corners than the final phage particles and with an internal core; the last particles contain the same proteins as the DNA-free 11 or 12-particles. These particles could represent a prohead state, ready for DNA encapsulation. None of the DNA-containing particles have the nonstructural proteins p7, p15 or p16, suggesting that these proteins are released from the proheads upon DNA encapsulation.     

Phosphatidylcholesterol bilayers. A model for phospholipid-cholesterol interaction

Aqueous dispersions of monovalent and divalent cation salts of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl) cholesterol form multilamellar vesicles as shown by freeze-fracture electron microscopy, by electron micrographs of the negatively stained liposomes, and by swelling curves of liposomes in hypoosmotic medium. Differential scanning calorimetry reveals that aqueous dispersions of divalent metal salts of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)-cholesterol undergo a characteristic thermotropic phase transition with a relatively large cooperative unit (n > 250 for the calcium salt). In contrast, monovalent cation salts of O-(1,2-dipalmitoyl-sn-glycerol-3-phosphoryl)cholesterol do not show a thermotropic phase transition under comparable conditions. The molecular area of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol in a monolayer is the same in the presence and absence of Ca²⁺, and is virtually equal to the area of an equimolar mixture of dipalmitoyl phosphatidic acid and cholesterol. To account for the novel state induced by Ca²⁺ on aqueous dispersions of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol (i.e., bilayer organization and highly cooperative phase transition), a linear array model is proposed in which Ca²⁺ bridges adjacent arrays of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol molecules, thus freezing the acyl chains in their normal state. One of the main corollaries of the model is that the cooperative unit for a thermotropic phase transition is essentially one-dimensional, rather than a two-dimensional matrix. O-(1,2-Dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol is proposed as an orientationally and conformationally restricted analog of glycerophospholipid plus cholesterol in bilayers.     

A family with a satellited Yq chromosome

Summary A large pedigree with a satellited Yq chromosome is described, Q, C, and NOR banding were performed. Family C proband suffers from a Klinefelter syndrome.     

Fetal cells in the maternal blood

Summary In an attempt to stimulate fetal cells in the maternal blood to mitotic division, peripheral blood lymphocytes were cultured from ten primiparous women and six multiparous women. In the case of the ten primiparous women, PWM was used to stimulate lymphocytes in 3- and 7-day cultures made at the 16th, 20th, 24th, and 28th week of gestation. Altogether, 10565 mitoses were analyzed after quinacrine staining of cells from five mothers who each subsequently gave birth to a male infant, and not a single XY mitosis was found.In the case of the multiparous women, lymphocyte cultures, with PHA or LPS as mitogen and MLC, were initiated between the 13th and 20th week of pregnancy. Four of the mothers were pregnant with a male child, and two with a female child. From cultures of each of the four mothers expecting a boy, a total of 9721 mitoses were analyzed after quinacrine staining, and not a single XY mitosis was found. However, one XY cell was found in the culture from one of the two women who delivered a girl. The XY mitosis probably originated from a pregnancy 8 months earlier which terminated in a male infant.In an attempt to culture and obtain good chromosome preparations from small numbers of cells, it was shown that a good mitotic response and good chromosome preparations could be obtained from as few as 6000 lymphocytes.