Size and organization of a multigene family encoding phaseolin, the major seed storage protein of Phaseolus vulgaris L.

Summary Solution hybridization kinetics and genomic nitrocellulose blot hybridization analyses show that the Phaseolus vulgaris L. (French bean) storage proteins (phaseolins) are encoded as a small, homologous, multigene family consisting of approximately seven members. Restriction endonuclease site mapping (EcoRI, BamHI, and BglII) of DNA regions flanking the phaseolin genes has shown that the gene family can be divided into at least three characteristic fragment size classes. Clones representative of two of these phaseolin gene classes have been isolated from a 1059 phage library.     

Actions of synthetic piperidine derivatives on an insect acetylcholine receptor/ion channel complex

The actions of synthetic piperidine derivatives on the response to ionophoretically-applied acetylcholine (ACh) have been tested on the cell body membrane of the fast coxal depressor motoneurone (F_f) of the cockroach Periplaneta americana. The cis form and the cis (80%):trans (20%) mixture of 2-methyl-6-undecyl piperidine were the most effective (the half-maximal blocking action of the mixed isomers was estimated to be 6.3 × 10^?5 M). Less potent was the cis (50%):trans (50%) mixture of 2-methyl-6-tridecyl piperidine. However, pure cis 2-methyl-6-tridecyl piperidine was even less effective than the mixed isomers, indicating that, in the case of the tridecyl derivative, the trans form was largely responsible for the block of the ACh response.Cis 2-Methyl-6-undecyl piperidine failed to inhibit the binding of N-[propionyl-³H] propionylated α-bungarotoxin to metathoracic ganglion homogenates at concentrations up to 1.0 × 10^?4 M. Also, block of ACh-induced current by 2-methyl-6-undecyl piperidine (cis 80%:trans 20%) was largely independent of membrane potential in the range ?120 mV to ?60 mV, indicating an interaction with the closed ACh receptor/ion channel complex at a site which, in the case of the cis isomer, is separate from the binding site for α-bungarotoxin.     

Aspects of the neuroendocrine control of ovulation and broodiness in the domestic hen

The neuroendocrine control of ovulation and broodiness in the domestic hen involves complex interactions between hypothalamic neuropeptides, neurotransmitters, and ovarian steroids which regulate the secretion of luteinizing hormone (LH) and prolactin. Nuclear progesterone receptor is localized in many neurons throughout the hypothalamus but is absent from LHRH neurons. Hence, the positive feedback action of progesterone on LH release is not mediated by a genomic mechanism within the LHRH neuron. Precursors of 5-hydroxytryptamine (5HT) and dopamine (DA) inhibit the preovulatory release of LH, while the turnover rates of these neurotransmitters in the anterior hypothalamus decrease when preovulatory levels of LH are at their highest. Further, a population of receptors for 5HT which occurs in the anterior hypothalamus in laying birds is absent in nonlaying, incubating hens. Taken together, these observations suggest that the preovulatory surge of LH is mediated by a transitory decrease in the inhibitory action of 5HT and possibly DA, on the secretion of LHRH. Neurons containing 5HT may play a role in the regulation of prolactin release and, more specifically, in the control of broodiness. Drugs which enhance the function of 5HT neurons stimulate prolactin release while increased prolactin secretion in incubating hens is associated with an increase in the turnover of 5HT in the anterior hypothalamus. No receptors for 5HT were demonstrable in the anterior pituitary gland, showing that the prolactin-releasing activity of 5HT must be mediated by a prolactin-releasing factor (PRF). A candidate for a physiological PRF is vasoactive intestinal polypeptide (VIP).(ABSTRACT TRUNCATED AT 250 WORDS)     

Photoaffinity labeling of the ouabain binding site in Na, K-ATPase in developing brine shrimp

Analysis of purified Na,K-ATPase from brine shrimp nauplii by sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals two large (alpha) subunits [G.L. Peterson, R.D. Ewing, S.R. Hootman, and F.P. Conte (1978) J. Biol. Chem. 253:4762]. The band with lower mobility in a neutral or alkaline gel is designated alpha 1 and the band with higher mobility alpha 2. Ouabain prevents dephosphorylation of both alpha 1 and alpha 2 as documented by gel analysis, but a higher concentration of ouabain is required to prevent dephosphorylation of alpha 2. The photoaffinity label, [3H]4'(2-ethyldiazomalonyl) digitoxigenin monodigitoxiside, specifically labels alpha in a ouabain-protectable manner without labeling other contaminating proteins in the preparation. Greater than 93% of the total ouabain-protectable labeling of the alpha subunits is associated with alpha 1. The photoaffinity label, [3H]4"' (2-ethyldiazomalonyl) digitoxin, specifically labels alpha 1 and beta in a ouabain-protectable manner without labeling other contaminating proteins. These data show that in the brine shrimp the third digitoxose residue of digitoxin binds in a region in which the alpha 1 and beta chains are in close proximity. Less than 5% of the specific ouabain-protectable labeling of total alpha is associated with alpha 2. These studies indicate that cardioactive steroids have higher affinity for the alpha 1 subunit.     

The groin flap in reparative surgery of the hand

The historical literature of the use of axial vascular pattern flaps from the hypogastric and iliofemoral regions in reparative surgery of the hand is concisely reviewed. Thirty-six iliofemoral (groin) flaps were utilized for delayed primary resurfacing and secondary reconstruction of defects of the hand and forearm. Two flaps (6 percent) were complicated by partial necrosis. We caution against the immediate resurfacing (within 24 hours of injury) of acute crushed hand wounds by distant flaps. The immediate application of a healthy flap on a soiled or crushed wound invites complications of local tissue necrosis, infection, and subsequent loss of the flap. When distant flaps are indicated for coverage of acute hand wounds, delayed primary coverage following complete removal of all nonviable tissue is a safe and reliable regimen. It is advantageous to design the serviceable portion of the flap on the distal area of the vascular territory of the groin flap. Thoughtful yet "radical" defatting can be performed on the lateral portion of the groin flap territory. Constructed in this way, the long medial base of the groin flap allows freedom for movement at the wrist and metacarpophalangeal and interphalangeal joints, thus decreasing edema and stiffness. In the management of soft-tissue defects in the hand requiring distant flap coverage, we choose to utilize the conventional groin flap in preference to the microvascular free flap when both techniques will deliver equal results.     

Studies of human achondroplasia: oxidative metabolism in tissue culture cells

Mitochondria prepared from the first growth of cells (fibroblasts) from skin biopsies from homozygous (but not heterozygous) achondroplastic human subjects were unable to carry out oxidative phosphorylation. However, successive crops of cells gained the ability to phosphorylate with normal P:O ratios with pyruvate-malate and succinate as substrates. Concentrations of cytochromes a + a3 were markedly and significantly lower in homogenates of homozygous achondroplastic tissue culture cells than in homogenates of normal cells. Levels of cytochromes a + a3 in the heterozygous achondroplastic cells were intermediate between the levels in normal cells and the homozygous achondroplastic cells. Activities of the mitochondrial oxidative systems (NADH, succinic and cytochrome oxidases) were not significantly lower in the achondroplastic cell preparations than in normal cell preparations under standard assay conditions (saturation levels of oxygen).     

Inhibition of prostaglandin biosynthesis by SQ 28,852, a 7-oxabicyclo[2.2.1]heptane analog

7-Oxabicyclo[2.2.1]heptane analogs of prostaglandin (PG) H2 can act as thromboxane (Tx) A2 receptor antagonists or agonists, PGI2 and/or PGD2 receptor agonists, or exhibit a mixture of the above activities. SQ 28,852, a new analog with a hexyloxymethyl omega side chain, is a potent inhibitor of PG synthesis. SQ 28,852 inhibited collagen and arachidonic acid (AA)-induced platelet aggregation and TxB2 and PGE2 formation, but did not block platelet aggregation induced by ADP or the TxA2 mimics, 9,11-azo PGH2, SQ 26,655, and U-46,619. It also blocked conversion of AA to TxB2, PGE2, and 6-keto PGF1 alpha by microsomal preparations of human platelets, bovine seminal vesicles, and bovine aortas, respectively, but did not inhibit the conversion of PGH2 to TxA2 by the platelet microsomal preparation. SQ 28,852 (p.o.) protected mice against the lethal effects of AA (75 mg/kg, i.v.). The I50 values for SQ 28,852, indomethacin and aspirin were 0.025, 0.05 and 15 mg/kg, respectively. Neither SQ 28,852 nor indomethacin protected mice from death caused by 9,11-azo PGH2. SQ 28,852 (0.01 to 1 mg/kg, i.v.) inhibited AA-induced bronchoconstriction in anesthetized guinea pigs for at least 60 min. As an inhibitor of AA-induced bronchoconstriction, SQ 28,852 was 16- and 45-times more potent than indomethacin at 3 and 60 min after i.v. administration, respectively. SQ 28,852 did not inhibit bronchoconstriction induced by histamine or 9,11-azo PGH2, indicating its specificity of action in vivo. SQ 28,852 is the first example of a new class of cyclooxygenase inhibitors whose structure is similar to that of the naturally occurring endoperoxide, PGH2.     

Influences of medium consistency and shoot density on in vitro shoot proliferation of Populus alba × P. grandidentata

The in vitro shoot proliferation of Populus alba × P. grandidentata was affected by the medium consistency and shoot density, but not by three sizes of vessels. After 4 weeks of culture, the fresh weight and number of shoots per explant on liquid medium were significantly greater than those on agar-solidified medium. In particular, 3.2 shoots, 7 mm or longer per explant, were produced on liquid medium compared with 1.6 shoots per explant or agar-solidified medium. The fresh weight per explant after 4 weeks of culture on liquid medium and agar-solidified medium were 0.68 and 0.25 g, respectively. Increasing the number of shoots per vessel slowed the growth of the explants as measured by fresh weight and the number of shoots produced. There was little difference in the number of shoots produced between vessels with 1 or 2 shoots per vessel, but there were many fewer shoots produced when 3 shoots were placed in each vessel.Journal Paper No. J-11977 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 2210.     

Malignant transformation of murine fibroblasts by a human c-Ha-ras-1 oncogene does not require a functional epidermal growth factor receptor.

Although mutations in ras genes are thought to be important for the development of about 20% of human tumors, almost nothing is known about the way in which these mutations lead to cellular transformation. The known biochemical properties of the 21-kilodalton ras proteins suggest that they may behave as G proteins, regulating the proliferation of cells in response to growth factor stimulation of a receptor. Although the putative receptor(s) has not been identified, several lines of evidence, in particular the fact that rodent cell lines containing ras oncogenes produce transforming growth factor alpha, have suggested that the epidermal growth factor (EGF) receptor is involved in ras transformation. Here we show that murine fibroblasts with no EGF receptors can be transformed to a completely malignant phenotype with a mutated ras gene. It appears, therefore, that the EGF receptor is not required for ras-mediated transformation of these cells.     

Preliminary characterization of a Chinese hamster ovary cell glycosylation mutant isolated by screening for low intracellular lysosomal enzyme activity

A novel screening procedure was developed for isolating Chinese hamster ovary cell mutants altered in the early steps of the biosynthesis of asparagine-linked glycoproteins. This procedure identifies cells with low intracellular levels of two lysosomal hydrolases, beta-glucuronidase and alpha-iduronidase. One mutant cell line isolated in this way, CHB 11-1-3, has low intracellular levels of seven lysosomal enzymes as compared to wild-type cells. Although CHB 11-1-3 synthesizes mannosylphosphoryldolichol and [Man]₅[NAcG1cNH₂]₂-P-P-lipid, it fails to utilize these lipid intermediates to make normal amounts of [Glc]₃[Man]₉[NAcG1cNH₂]₂P-P-lipid. As a consequence of this glycosylation defect, this mutant transfers oligosaccharides of a different structure than wild type to the lysosomal enzyme beta-hexosaminidase. In addition, it underglycosylates its proteins.