The effect of prostaglandins A2,E1,E2,15 methyl E2, 16, 16 dimethyl E2 and F2α on erythropoiesis

Prostaglandins A₂, E₁, E₂, methylated E₂s and F₂α affected erythropoiesis and/or erythropoietin (Ep) production. This action is indicated in the exhypoxic, polycythemic mouse where radioiron incorporations into RBC increased after administration of these compounds. The kidney and liver have been indicated through previous studies, to actively participate in Ep production. By the removal of one of these active sites in a murine system treated with prostaglandins it is shown that a response is reflected in Ep levels. Interference of the action of prostaglandins (PG) is altered by the removal of one of these target sites of Ep production. The erythropoietic responses elicited by PGA₂, E₁, and perhaps the methylated PGE₂s act through the liver whereas PGE₂ may operate through a renal pathway for its response. PGF_2α reveals no effect on erythropoietic activity and is no different than that observed for vehicle-treated controls. The prostaglandins tested appear to act primarily through the kidney or liver but the possibility exists that some yet undetermined organ site may also be involved.     

Sesquiterpenes of thalloid liverworts of the genera Conocephalum,Lunularia, Metzgeria and Riccardia

Thalloid liverworts of orders Metzgeriales and Marchantiales elaborate essential oils distinguishable from those of the Jungermanniales by the absence of β-barbatene and anastreptene. Riccardia sinuata elaborates a novel tricyclic exomethylene sesquiterpene of as yet undetermined structure. Conocephalum conicum elaborates cadinene-type sesquiterpenes. β-Cadinene from the latter species is clearly enantiomeric to the same product from vascular plants.     

Characterization of ionomycin as a calcium ionophore.

The ionophorous properties of a new antibiotic, ionomycin, have been studied. It was found that the antibiotic is capable of extracting calcium ion from the bulk of an aqueous phase into an organic phase. The antibiotic also acts as a mobile ion carrier to transport the cation across a solvent barrier. The divalent cation selectivity order for ionomycin as determined by ion competition experiments was found to be: Ca greater than Mg greater than Sr = Ba, where the binding of strontium and barium by the antibiotic is insignificant. The antibiotic also binds La3+ to some extent, but its complexation with monovalent alkali metal ions is negligible. Measurement of the binding of ionomycin with Ca2+ indicates that ionomycin complexes and transports calcium ion in a one to one stoichiometry.     

Bound Form Indole-3-acetic Acid Synthesis in Tumorous and Nontumorous Species of Nicotiana

The synthesis of H₂O-soluble and NaOH-hydrolyzable bound forms of indole-3-acetic acid (IAA) in petiole slices of Nicotiana glauca, Nicotiana langsdorffii, and their tumorous and nontumorous hybrids in the presence of exogenous ¹⁴C-IAA was investigated. The synthesis of conjugates progressively increased during 6 hours of incubation in ¹⁴C-IAA. The results showed that the rate of synthesis of IAA conjugates was higher in tumorous hybrids supplied exogenous IAA than in the parental species similarly supplied, and the rate of synthesis was higher in amphidiploid tumor plants than in a nontumorous mutant. It was also found that after 10 to 12 hours of incubation, 45% of the IAA taken up by F1 hybrids was in conjugated form whereas only 10 to 25% of the IAA taken up by a nontumorous mutant, N. langsdorffii, or N. glauca was conjugated. An F1 hybrid and an amphidiploid hybrid were found equally efficient in conjugating exogenously supplied IAA. It is postulated on the basis of these and other findings that IAA conjugates play an important role in tumorigenesis in Nicotiana.     

DNA-DNA gyrase complex: the wrapping of the DNA duplex outside the enzyme.

Digestion of the complex between double-stranded DNA and M. luteus or E. coli DNA gyrase with staphylococcal nuclease gives a 143 ± 3 base pair DNA fragment containing no single-chain scissions. Digestion of the same complex with bovine pancreatic DNAase I gives six discernible single-stranded DNA bands upon electrophoresis of the product in a denaturing gel. The lengths of these fragments, in number of nucleotides, are measured to be 47 ± 1, 57 ± 1, 67 ± 1, 77 ± 1, 86 ± 1 and 96 ± 1, respectively. These results support the notion that in the DNA-gyrase complex, a segment(s) of the DNA helix is wrapped around the enzyme. The wrapping of the DNA around the enzyme has been proposed previously based on the observation that in the absence of ATP, the linking number of a duplex DNA ring covalently closed by ligase in the presence of bound gyrase is higher than in the absence of gyrase (Liu and Wang, 1978). The coiling of DNA around the enzyme in the complex is believed to be intimately related to the ATP-dependent negative supercoiling of covalently closed duplex DNA ring by DNA gyrase. It has also been observed that digestion of pure double-stranded DNA by pancreatic DNAase I in the presence of calcium phosphate precipitate or solid hydroxylapatite gives a ladder of single-stranded DNA fragments of integral multiples of 10 nucleotides. This finding suggests that such a pancreatic DNAase I cleavage pattern is indicative of a DNA duplex lying on the outside of a surface.     

Dominance of colchicine resistance in hybrid CHO cells

Intraspecific hybrids of colchicine-sensitive with colchicine-resistant (CHR) Chinese hamster ovary cells were constructed, using six different colchicine-resistant clones from two independent series. In each instance, colchicine resistance was expressed in an incompletely dominant manner. Some hybrid clones were examined further for the expression of the pleiotropic CHR phenotype and for the cell surface P glycoprotein. These features of the colchicine-resistant phenotype were also expressed coordinately.     

北京猿人洞穴堆积反映的古气候变化及气候地层上的对比

周口店第一地点洞穴堆积厚达40余米,可划分为17层。它们分别由角砾层与非角砾层(灰烬层、泥砂层以及钟乳石层)等组成。其中角砾层代表冰期、寒冷期或氧同位素的偶数阶段;非角砾层则代表间冰期、温暖期或氧同位素的奇数阶段。它们表明:在中更新世时,周口店地区气候的冷暖变化是明显的,而且气候的大陆性程度有逐渐加强的趋势。第一地点、新洞以及山顶洞等地的沉积物与洞外堆积、陕西洛川的黄土以及深海沉积物等均可进行气候地层学上的对比。     

武汉地区的水绵

作者自1965年开始即从事湖北省双星藻科植物标本的采集。在武汉地区采得水绵属(Spirogyra)标本中,鉴定了28个种和两个变型。其中有5个种(扩大水绵,双形水绵,长圆水绵,伪美丽水绵,武昌水绵)和两个变型(泡状水绵小形变型,网纹水绵柱孢变型)在目前可以认为是武汉地区特有的种;有5个种(泡状水绵,陈氏水绵,河北水绵,丘疹水绵,青岛水绵)是我国的特有种;有两个种(隐纹水绵,雅托巴水绵)是     

Somatic embryogenesis and plant regeneration in an interspecific hybrid of Oryza

An embryogenic callus was obtained from immature panicle of an interspecific hybrid (Oryza sativa x O. latifolia) F₁. The medium consisted of HE salts supplemented with 2,4-D, NAA (each 2 mg/l), kinetin (3 mg/l), yeast extract (1360 mg/l) and casein hydrolyzate (300 mg/l). The callus was milk-white in colour compact and granulate in texture. Various developmental stage of embryoid, such as globular, heart-shape, scutellum-shape and mature embryoid were observed in an embryogenic callus. Plantlets were successfully regenerated from 1-month-old callus with more than 80% regenerational frequency in each subculture for 12 passages.