New species and combinations in neotropical Lecythidaceae

Lecythis barnebyi Mori andCorythophora amapaensis Pires ex Mori & Prance are described and the following new combinations are coined:Lecythis brancoensis (R. Knuth) Mori,L. schwackei (R. Knuth) Mori,L. alutacea (A. C. Smith) Mori,L. lurida (Miers)Mori, L. holcogyne (Sandwith)Mori, L. corrugata Poiteau subsp.rosea (Spruce ex Berg) Mori, andCorythophora labriculata (Eyma) Mori & Prance.     

Unsaturated diacylglycerol as a possible messenger for the activation of calcium-activated, phospholipid-dependent protein kinase system

A small quantity of unsaturated diacylglycerol (DG) sharply decreased the Ca²⁺ and phospholipid concentrations needed for full activation of a Ca²⁺-activated, phospholipid-dependent multifunctional protein kinase described earlier (Takai, Y., Kishimoto, A., Iwasa, Y., Kawahara, Y., Mori, T. and Nishizuka, Y. (1979)$\text{J.}\text{Biol.}\text{Chem.}\text{254}$. 3692–3695). In the presence of unsaturated DG and micromolar order of Ca²⁺, phosphatidylserine (PS) was most relevant with the capacity to activate the enzyme, whereas phosphatidylethanolamine and phosphatidylinositol (PI) were far less effective. Phosphatidylcholine was practically inactive. It is possible, therefore, that unsaturated DG, which may be derived from PI turnover provoked by various extracellular stimulators, acts as a messenger for activating the enzyme, and that Ca²⁺ and various phospholipids such as PI and PS seem to play a role cooperatively in this unique receptor mechanism.     

Clones of Friend leukemia cells: differences in karyotypes and responsiveness to inducers of differentiation.

Several clones of Friend leukemia cells have been established which differ in their chromosome composition. These cells also vary with regard to their responsiveness to DMSO, whereas all are responsive to butyric acid. Hence, there appears to be independent assortment of the ability of a cell line to respond to DMSO and to butyric acid, suggesting a different mechanism of action for each agent. Further, individual Friend cells possess the ability to simultaneously contain chloroacetate esterase and heme--two biochemical properties which have previously been believed to be mutually exclusive.     

The physiological significance of the xanthurenic acid-insulin comples.

The xanthurenic acid-insulin complex was found to have similar immunological properties to native Zn-insulin. This complex showed less hormonal activity on glucose metabolism in adipose tissue than native An-insulin, but its activity was increased by addition of Zn2+ ions.     

Effect of angiotensin II type 2 receptor on tyrosine kinase Pyk2 and c-Jun NH2-terminal kinase via SHP-1 tyrosine phosphatase activity: evidence from vascular-targeted transgenic mice of AT2 receptor

Angiotensin II (Ang II) has two major receptor isoforms, AT1 and AT2. AT1 transphosphorylates Ca(2+)-sensitive tyrosine kinase Pyk2 to activate c-Jun NH2-terminal kinase (JNK). Although AT2 inactivates extracellular signal-regulated kinase (ERK) via tyrosine phosphatases (PTP), the action of AT2 on Pyk2 and JNK remains undefined. Using AT2-overexpressing vascular smooth muscle cells (AT2-VSMC) from AT2-transgenic mice, we studied these undefined actions of AT2. AT1-mediated JNK activity was increased 2.2-fold by AT2 inhibition, which was abolished by orthovanadate. AT2 did not affect AT1-mediated Pyk2 phosphorylation, but attenuated c-Jun mRNA accumulation by 32%. The activity of src-homology 2 domain-containing PTP (SHP-1) was significantly upregulated 1 min after AT2 stimulation. Stable overexpression of SHP-1 dominant negative mutant in AT2-VSMC completely abolished AT2-mediated inhibition of JNK activation and c-Jun expression. These findings suggest that AT2 inhibits JNK activity by affecting the downstream signal of Pyk2 in a SHP-1-dependent manner, leading to a decrease in c-Jun expression.     

Differential regulation of thyrotropin-releasing hormone receptor mRNA levels by thyroid hormone in vivo and in vitro (GH3 cells).

We studied the effect of thyroid status on thyrotropin-releasing hormone receptor (TRH-R) mRNA levels both in vivo and in vitro (GH3 cells) using a cloned rat TRH-R cDNA by RT-PCR. Experimental hypothyroid rats were produced by total thyroidectomy and were then killed 7 days after the operation. TRH receptor binding in the anterior pituitary and serum TSH level were elevated approximately 2-fold and 8-fold, respectively, in 7 day thyroidectomized rats. TRH-R mRNA levels in hypothyroid rats were also increased significantly compared with those of normal rats. In GH3 cells, however, no significant change of TRH-R mRNA level was observed between cultures treated with triiodothyronine (T3, 10(-9) and 10(-7) M) and the untreated group. The present data indicate that 1) the in vivo effects of thyroid status on TRH-R mRNA levels differ from the in vitro one, and that 2) the down regulation of TRH-R binding by thyroid hormone in GH3 cells may be mediated by translational or post-translational mechanisms.     

Molecular cloning of three homoeologous cDNAs encoding orthologs of the maize KNOTTED1 homeobox protein from young spikes of hexaploid wheat

The plant knotted1 (kn1)-like homeobox genes are known to play important roles in the maintenance of shoot apical meristem (SAM), determination of cell fate and differentiation of vegetative tissues. To study structural diversity of the three homologous loci encoding a KN1-like homeobox protein in the hexaploid wheat genome, we isolated clones from a cDNA library of young spikes of Japanese common wheat cultivar 'Norin 26'. Three different but highly homologous cDNAs were isolated and their sequences were determined. The mean homology of the deduced amino acid sequences was 96% as compared to the barley ortholog KNOX3. The wheat kn1-like homeobox proteins named WKNOX1 are encoded by a single set of homologous genes on the homologous group 4 chromosomes in the three component genomes of common wheat, i.e. 4A, 4B and 4D. The nucleotide sequence data and the Southern blot pattern suggested that the three homologous loci of wknox1 genes are highly conserved through polyploid evolution of wheat. They were expressed in SAM-containing shoots and young spikes but not in developed leaves, glumes and lemmas and callus tissues. The ectopic expression of the wknox1 was observed in lemma of wheat Hooded (Hd) mutants. The result suggested that the Hd gene is a dominant allele of the wknox1 locus on chromosome 4A.     

The nucleotide sequence of a cDNA clone containing the entire coding region for mouse X-chromosome-linked phosphoglycerate kinase

A clone containing cDNA for X chromosome-linked phosphoglycerate kinase (PGK-1) was isolated from a mouse myeloma cDNA library. The nucleotide (nt) sequence of the cDNA has been determined, and the amino acid (aa) sequence of the enzyme thereby deduced. At the nt level, the coding region of mouse PGK cDNA has 93% homology with human X-linked cDNA and 60% homology with the yeast gene. Mouse PGK-1 protein contains 416 aa and is 98%, 96% and 64% homologous with human, horse, and yeast enzyme sequences, respectively.