The effects of androgens on the β-glands of the tokay (Gekko gecko): Modification of an hypothesis

Study of the posterior abdominal epidermis in hypophysectomized/thyroidectomized male and female tokays following surgery, and subsequent androgen therapy, indicates that, contrary to a previous model, all aspects of β-gland differentiation are under direct androgenic control. On the other hand, another epidermal specialization, the digital foot-pad, shows a pattern of histogenesis directly comparable to that of β-glands, but is unaffected by androgens. These data are discussed with respect to the evolution of glandular epidermal specializations in gekkonid lizards and the possible role of androgens in modifying the control of cell differentiation in lizard epidermis.     

Differentiation properties of pure populations of human dystrophic muscle cells

The interpretation of the majority of studies of Duchenne muscular dystrophy (DMD) has been complicated by the heterogeneous composition of the cultures used. In addition to muscle cells, muscle tissue contains adipocytes and fibroblasts and the proportion of these cell types varies, especially in disease states. To overcome this problem we developed culture conditions which permitted isolation and characterization of pure populations of clonally derived human muscle cells [1, 2]. Here we report the successful application of these methods to muscle cells from biopsies of individuals with diagnosed DMD. The normal and mutant human muscle cells were used in experiments of muscle differentiation in the same manner as cell lines. Frozen-stored cells were thawed, plated in a series of replicate plates, and allowed to differentiate under similar culture conditions. Yet, in contrast with cell lines, the cells were karyotypically normal, not altered by adaptation to long-term culture, and had a finite lifespan. We have systematically analysed specific properties of the normal and DMD muscle cells which differentiated in culture. The kinetics and extent of myoblast fusion, myotube morphology, and the accumulation and distribution of membrane acetylcholine receptors were monitored. In addition, the isozyme composition of creatine kinase and its intracellular and extracellular distribution were determined. Our results indicate that DMD muscle cells are fully capable of initiating myogenesis in culture and do not differ from normal muscle in several important parameters of differentiation.     

EFFECTS OF FERTILIZATION ON EPICUTICULAR WAX MORPHOLOGY OF NEEDLE LEAVES OF DOUGLAS FIR,PSEUDOTSUGA MENZIESII (PINACEAE)

Fertilized stands of Pseudotsuga menziesii were found to have glaucous needles. We investigated the morphological and quantitative characteristics of the epicuticular waxes of needles of fertilized and control trees. Glaucousness was caused by ornate tubular epicuticular wax. Dipping needles in chloroform, which dissolves waxes, eliminated the glaucous appearance. Based on cryostage scanning electron microscopic observations, the epicuticular waxes in the nonstomatal region were much more ornate on the needles of the fertilized trees (experimental needles) than in unfertilized trees (control needles). The stomatal region in both experimental and control needles showed similarly ornate waxes. Quantities of waxes were similar in experimental and control needles. The glaucousness was not the result of greater quantities of wax; rather, fertilization altered wax morphology in the nonstomatal regions.     

A high-pressure liquid chromatographic method for measuring 3', 5'-cyclic AMP in brain.

A method is described for the estimation of adenosine 3′,5′-monophosphate (3′,5′-cyclic AMP) in rat brain by high-pressure liquid chromatography (HPLC). The nucleotide is purified initially by being passed through two columns, alumina and AG-1X2. The peak in HPLC was identified by a number of methods. Optimum parameters for HPLC were obtained by using 1 mm KH₂PO₄ buffer, pH 4.8, at a flow rate of 57 ml/hr at room temperature. Using this technique the concentration of 3′,5′-cyclic AMP in rat brain was found to be 2.53 ± 0.40 nmol/g (mean ± SD, n = 5).     

Sexual development of patients with isochromosomes for the long arm of the X chromosome

Summary The sexual development of 14 girls with non-mosaic monocentric 46,X,iXq karyotype was studied. Seven out of eight girls were found to have immature secondary sexual characteristics and amenorrhoea, a finding greatly contrasting with that in Triplo-X girls. The relative ineffectiveness of the isochromosome Xq in maintaining fertility may be due to the absence of one short arm, which probably also carries a gonadal determinant. Alternatively, the presence of two inactivation sites on one isochromosome may render the gonadal determinants inactive at an important stage in gonadal development.     

Transbilayer distribution and mobility of phosphatidylinositol in human red blood cells

The present studies describe the distribution of phosphatidylinositol (PI) within the membrane bilayer of the human red blood cell (RBC) as well as its transbilayer mobility. The membrane bilayer distribution was determined by measuring the hydrolysis of PI in the exterior leaflet of the RBC membrane using a PI-specific phospholipase C and by extraction of PI from the exterior leaflet using bovine serum albumin. The transbilayer mobility of PI was measured by following the fate of radiolabeled PI which was first incorporated into the outer leaflet of the RBC membrane. Our results indicate that PI is asymmetrically distributed in the membrane, with approximately 80% located in the inner and 20% in the outer leaflet of the bilayer. The rate of transbilayer mobility of PI is similar to that for certain molecular species of phosphatidylcholine and much slower than that reported for the aminophospholipids in the RBC membrane.     

Histidine:pyruvate transamination and phyenylalanine:pyruvate transamination may be catalyzed by the same enzyme.

Some properties of histidine:pyruvate transaminase (HPT) and phenylalanine:pyruvate transaminase (PPT) in the cytosol of rat liver were studied. HPT and PPT activity could not be separated by DEAE-Sephadex A-50 or hydroxylapatite column chromatography, and the ratio of $\text{HPT}\text{PPT}$ activity remained constant during these purification procedures. The two enzyme activities also showed similar heat stability and responses to glucagon injection. Based on these findings, we suggest that a single enzyme may specifically catalyze histidine:pyruvate and phenylalanine:pyruvate transamination.     

Heterology expression of the Arabidopsis C-repeat/dehydration response element binding factor 1 gene confers elevated tolerance to chilling and oxidative stresses in transgenic tomato

In an attempt to improve stress tolerance of tomato (Lycopersicon esculentum) plants, an expression vector containing an Arabidopsis C-repeat/dehydration responsive element binding factor 1 (CBF1) cDNA driven by a cauliflower mosaic virus 35S promoter was transferred into tomato plants. Transgenic expression of CBF1 was proved by northern- and western-blot analyses. The degree of chilling tolerance of transgenic T(1) and T(2) plants was found to be significantly greater than that of wild-type tomato plants as measured by survival rate, chlorophyll fluorescence value, and radical elongation. The transgenic tomato plants exhibited patterns of growth retardation; however, they resumed normal growth after GA(3) (gibberellic acid) treatment. More importantly, GA(3)-treated transgenic plants still exhibited a greater degree of chilling tolerance compared with wild-type plants. Subtractive hybridization was performed to isolate the responsive genes of heterologous Arabidopsis CBF1 in transgenic tomato plants. CATALASE1 (CAT1) was obtained and showed activation in transgenic tomato plants. The CAT1 gene and catalase activity were also highly induced in the transgenic tomato plants. The level of H(2)O(2) in the transgenic plants was lower than that in the wild-type plants under either normal or cold conditions. The transgenic plants also exhibited considerable tolerance against oxidative damage induced by methyl viologen. Results from the current study suggest that heterologous CBF1 expression in transgenic tomato plants may induce several oxidative-stress responsive genes to protect from chilling stress.     

The plant glycosyltransferase clone collection for functional genomics

The glycosyltransferases (GTs) are an important and functionally diverse family of enzymes involved in glycan and glycoside biosynthesis. Plants have evolved large families of GTs which undertake the array of glycosylation reactions that occur during plant development and growth. Based on the Carbohydrate‐Active enZymes (CAZy) database, the genome of the reference plant Arabidopsis thaliana codes for over 450 GTs, while the rice genome (Oryza sativa) contains over 600 members. Collectively, GTs from these reference plants can be classified into over 40 distinct GT families. Although these enzymes are involved in many important plant specific processes such as cell‐wall and secondary metabolite biosynthesis, few have been functionally characterized. We have sought to develop a plant GTs clone resource that will enable functional genomic approaches to be undertaken by the plant research community. In total, 403 (88%) of CAZy defined Arabidopsis GTs have been cloned, while 96 (15%) of the GTs coded by rice have been cloned. The collection resulted in the update of a number of Arabidopsis GT gene models. The clones represent full‐length coding sequences without termination codons and are Gateway^® compatible. To demonstrate the utility of this JBEI GT Collection, a set of efficient particle bombardment plasmids (pBullet) was also constructed with markers for the endomembrane. The utility of the pBullet collection was demonstrated by localizing all members of the Arabidopsis GT14 family to the Golgi apparatus or the endoplasmic reticulum (ER). Updates to these resources are available at the JBEI GT Collection website http://www.addgene.org/ .