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.     

Sequence homology between human alpha 1-antichymotrypsin, alpha 1-antitrypsin, and antithrombin III

alpha 1-Antichymotrypsin mRNA was isolated by specific polysome immunoprecipitation from turpentine-treated baboon liver. The highly enriched mRNA was used for synthesis and cloning of the corresponding cDNA. Baboon alpha 1-antichymotrypsin cDNA clones were identified by hybrid-selected translation, and the insert DNA fragment from one of the putative clones was used as a probe to screen a human liver cDNA library comprised of 40 000 independent transformants. One of the human cDNA clones was unambiguously identified to contain alpha 1-antichymotrypsin DNA sequences by comparison of its 5'-terminal nucleotide sequence with the N-terminal amino acid sequence of the protein. This cDNA clone, designated phACT235, contains 1524 base pairs of human DNA, which was sequenced in its entirety. The inserted DNA codes for a 25 amino acid signal peptide sequence and the entire mature alpha 1-antichymotrypsin of 408 amino acid residues. Comparison of the amino acid sequence of alpha 1-antichymotrypsin with that of the human alpha 1-antitrypsin has revealed a homology level similar to that between chymotrypsin and trypsin.     

Thyroid hormones in cyclostomes and fish and their role in regulation of intermediary metabolism

1. Experimental data obtained in cyclostomes and fish concerning the plasma levels of thyroxine and tri-iodothyronine as well as their influence on intermediary metabolism of lipids, carbohydrates, and proteins are reviewed. 2. The information dealing with the physiological role of thyroid hormones in regulation of metabolic processes seems to be scarce in cyclostomes and controversial in fishes. 3. Nevertheless, the data covered in the review support the generalization that thyroid hormones, probably along with some other hormones, exert a regulatory action on the metabolic processes already on the lower stage of the evolution of poikilothermic vertebrates.     

The isolation and properties of phenylalanine hydroxylase from human liver

Phenylalanine hydroxylase was prepared from human foetal liver and purified 800-fold; it appeared to be essentially pure. The phenylalanine hydroxylase activity of the liver was confined to a single protein of mol.wt. approx. 108000, but omission of a preliminary filtration step resulted in partial conversion into a second enzymically active protein of mol.wt. approx. 250000. Human adult and full-term infant liver also contained a single phenylalanine hydroxylase with molecular weights and kinetic parameters the same as those of the foetal enzyme; foetal, newborn and adult phenylalanine hydroxylase are probably identical. The K(m) values for phenylalanine and cofactor were respectively one-quarter and twice those found for rat liver phenylalanine hydroxylase. As with the rat enzyme, human phenylalanine hydroxylase acted also on p-fluorophenylalanine, which was inhibitory at high concentrations, and p-chlorophenylalanine acted as an inhibitor competing with phenylalanine. Iron-chelating and copper-chelating agents inhibited human phenylalanine hydroxylase. Thiol-binding reagents inhibited the enzyme but, as with the rat enzyme, phenylalanine both stabilized the human enzyme and offered some protection against these inhibitors. It is hoped that isolation of the normal enzyme will further the study of phenylketonuria.     

Vasoactive properties of dihomo-gamma-linolenic acid and series one prostaglandins in a freshwater teleost, Channa maculata

1. Prostaglandins A1, B1, E1 and F1 alpha (2-120 micrograms/kg), arachidonic acid and dihomo-gamma-linolenic acid (0.1-2 mg/kg) were injected intravenously into Channa maculata and changes in arterial blood pressure were recorded. 2. Injection of PGF1 alpha had no significant effect on arterial blood pressure. Injection of PGA1 and PGE1 was followed by dose-dependent hypotension whereas injection of PGB1 elicited significant dose-dependent increase in arterial blood pressure. 3. Both dihomo-gamma-linolenic acid and arachidonic acid were also depressor agents but dihomo-gamma-linolenic acid was more potent. 4. A single bolus intravenous injection of indomethacin (5 mg/kg) or 4 daily intraperitoneal injections (4 x 10 mg/kg) significantly lowered arterial blood pressure. One hour after pre-treatment of indomethacin, the vascular effects of both prostaglandin precursors were abolished. 5. It appears that the vascular effects of prostaglandins in Channa maculata are qualitatively different from those reported for mammals.     

Synteny on mouse chromosome 5 of homologs for human DNA loci linked to the Huntington disease gene

Comparative mapping in man and mouse has revealed frequent conservation of chromosomal segments, offering a potential approach to human disease genes via their murine homologs. Using DNA markers near the Huntington disease gene on the short arm of chromosome 4, we defined a conserved linkage group on mouse chromosome 5. Linkage analyses using recombinant inbred strains, a standard outcross, and an interspecific backcross were used to assign homologs for five human loci, D4S43, D4S62, QDPR, D4S76, and D4S80, to chromosome 5 and to determine their relationships with previously mapped markers for this autosome. The relative order of the conserved loci was preserved in a linkage group that spanned 13% recombination in the interspecific backcross analysis. The most proximal of the conserved markers on the mouse map, D4S43h, showed no recombination with Emv-1, an endogenous ecotropic virus, in 84 outcross progeny and 19 recombinant inbred strains. Hx, a dominant mutation that causes deformities in limb development, maps approximately 2 cM proximal to Emv-1. Since the human D4S43 locus is less than 1 cM proximal to HD near the telomere of chromosome 4, the murine counterpart of the HD gene might lie between Hx and Emv-1 or D4S43h. Cloning of the region between these markers could generate new probes for conserved human sequences in the vicinity of the HD gene or possibly candidates for the murine counterpart of this human disease locus.     

Human serum amyloid A protein. The assignment of the six major isoforms to three published gene sequences and evidence for two genetic loci

Serum amyloid A protein (apo-SAA) is an acute-phase reactant and an apolipoprotein of high density lipoproteins (HDL). Six major isoforms of apo-SAA occur in humans (pI 6.0, 6.4, 7.0, 7.4, 7.5, 8.0). In this report we have rationalized the phenotypic expression of apo-SAA isoforms with published apo-SAA structures predicted from apo-SAA cDNA's pA1 and pSAA82 and the genomic DNA SAAg9. The six apo-SAA isoforms fall into three pairs, pI 6.0/6.4, 7.0/7.5, and 7.4/8.0, which are products of cDNA pA1, cDNA pSAA82, and genomic DNA SAAg9, respectively. The second of each isoform pair (i.e. pI 6.4, 7.5, and 8.0) is the "primary" product: a 104-residue peptide with the NH2-terminal sequence Arg-Ser-Phe-Phe. Each primary product is processed either to a major 103-residue peptide with the NH2-terminal sequence Ser-Phe-Phe or processed to a minor 102-residue product which results from the loss of both an Arg and a Ser residue from the NH2 termini. These "secondary" products have the lower pI values of 6.0, 7.0, and 7.4, respectively. The isoelectric points of the SAAg9 products were confirmed by expression of SAAg9 in transfected mouse L-cells. Both the pI 8.0 and 7.4 isoforms were present in cellular extracts, suggesting that post-translational modification of apo-SAA may occur intracellularly. However, the greater relative abundance of the pI 7.4 isoform extracellularly suggests that the major conversion may occur after secretion. Whereas the gene corresponding to the pA1 cDNA sequence does not show allelic variation, the segregation characteristics of the pI 7.0/7.5 and 7.4/8.0 isoform pairs amongst individuals suggests that these isoforms are the products of genes (with sequences corresponding to pSAA82 and SAAg9, respectively) which are allelic variants at a single locus distinct from that for the pI 6.0/6.4 isoform pair.     

Long-acting nifedipine versus metoprolol as monotherapy for essential hypertension. A randomized,controlled crossover study.

We assessed the efficacy of long-acting nifedipine as monotherapy in 52 patients with mild to moderate essential hypertension in a randomized, controlled crossover study. Good blood pressure control was achieved in 34 of 40 patients (85%) receiving nifedipine (mean daily dose, 52 mg in 2 divided doses) compared with 23 of 40 patients (58%) receiving metoprolol (mean daily dose, 155 mg in 2 divided doses). After treatment for 4 weeks, the mean blood pressures with nifedipine (149.7 +/- 16.6/88.7 +/- 11.1 mm of mercury) and metoprolol administration (163.9 +/- 23.3/94.2 +/- 10.2 mm of mercury) were significantly lower than with placebo (176.7 +/- 17.3/100.9 +/- 7.1 mm of mercury) (P less than .05). The mean systolic pressure during nifedipine treatment was 14.2 mm of mercury lower (95% confidence interval [CI], 3.9 to 24.5 mm of mercury) and mean diastolic pressure 5.5 mm of mercury (95% CI, 0.3 to 10.7 mm of mercury) lower than with metoprolol therapy. Both drugs were reasonably well tolerated, and intolerance requiring withdrawal was encountered in 3 of 45 (7%) patients receiving nifedipine, compared with 1 of 45 (2%) of those taking metoprolol and placebo, respectively. Adverse effects of nifedipine, most of which were transient, included palpitations, headache, facial flushing, and ankle edema. Long-acting nifedipine is a promising agent when given alone for mild to moderate hypertension and can be safely administered in clinical practice.