Effects of ingested phytoecdysteroids on the growth and development of two Lepidopterous larvae

The effects of ingested or injected 20-hydroxyecdysone on silkworm larvae (Bombyx mori) including death without moulting, death following completion of promoted moulting, death during promoted moulting (ecdysis inhibition) and inhibition in growth with and without effects on moulting, are dependent upon the concentration of exogenous hormone, the precise developmental stage of the treated larvae, and the duration of exposure to the exogenous ecdysteroid. Comparisons of 20-hydroxyecdysone with other phytoecdysteroids in the silkworm and pink bollworm, Pectinophora gossypiella, show a similar but more potent effect induced by ponasterone A, while cyasterone causes an ‘antiecdysone’ effect.     

Hydroxyl ion movements across the human erythrocyte membrane. Measurement of rapid pH changes in red cell suspensions

A stopped flow rapid reaction apparatus capable of following changes of ±0.02 pH unit in 0.1 ml of solution in less than 0.005 sec has been developed, utilizing a commercially available pH-sensitive glass electrode. Using this instrument, extracellular pH at 37°C was followed from less than 0.025 sec to 300 sec after mixing equal volumes of the following CO₂-free solutions: (A) normal human red cells, washed three times and resuspended in 150 mM NaCl at pH 7.2 with a hematocrit of 18%; and, (B) 150 mM NaCl adjusted with HCl or NaOH to pH 2.1 to pH 10.3. A minimum of 2 ml of mixture had to flow through the electrode chamber to ensure complete washout. The mixing process produced a step change in the pH of the extracellular fluid, after which exchanges across the red cell membrane and buffering by intracellular hemoglobin caused it to return toward pH 7.2 with an approximately exponential time course. Under the assumption that pH changes after mixing represent exchanges of hydroxyl for chloride ions across the cell membrane, hydroxyl ion permeabilities (P _OH ^- in cm/sec) were calculated and found to vary from 2 x 10^-4 at pH 9 to 4 x 10^-1 at pH 4 according to the empirical relationship P _OH ^- = 170 exp (-1.51 pH). The form of the dependence of P _OH ^- on extracellular pH does not appear compatible with a simple fixed charge theory of membrane permselectivity.     

Chromosomal mapping in the mouse of eight K-channel-genes representing the four Shaker-like subfamilies Shaker, Shab, Shaw, and Shal

The four Shaker-like subfamilies of Shaker-, Shab-,Shaw-, and Shal-related K⁺ channels in mammals have been defined on the basis of their sequence homologies to the corresponding Drosophila genes. Using interspecific backcrosses between Mus musculus and Mus spretus, we have chromosomally mapped in the mouse the Shaker-related K⁺-channel genes Kcna1, Kcna2, Kcna4, Kcna5, and Kcna6; the Shab-related gene Kcnb1; the Shaw-related gene Kcnc4; and the Shal-related gene Kcnd2. The following localizations were determined: Chr 2, cen-Acra-Kcna4-Pax-6-a-Pck-1-Kras-3-Kcnb1 (corresponding human Chrs 11p and 20q, respectively); Chr 3, cen-Hao-2-(Kcna2, Kcnc4)-Amy-1 (human Chr 1); and Chr 6, cen-Cola-2-Met-Kcnd2-Cpa-Tcrb-adr/Clc-1-Hox-1.1-Myk-103-Raf-1-(Tpi-1, Kcna1, Kcna5, Kcna6) (human Chrs 7q and 12p, respectively). Thus, there is a cluster of at least three Shaker-related K⁺-channel genes on distal mouse Chr 6 and a cluster on Chr 2 that at least consists of one Shaker-related and one Shaw-related gene. The three other K⁺-channel genes are not linked to each other. The map positions of the different types of K⁺-channel genes in the mouse are discussed in relation to those of their homologs in man and to hereditary diseases of mouse and man that might involve K⁺ channels.     

Insect Ecdysis Inhibitors from the East African Medicinal Plant Ajuga remota (Labiatae)

γ-Glutamy Icy steine synthetase was purified from E. coli B. The enzyme had a molecular weight of 5.5 × 10⁴ and required only magnesium ion for activity. The optimal pH and temperature for reaction were 8.5 and 45°C, respectively. The Km values for l-glutamate, l-cysteine, and ATP were 0.50, 0.09, and 0.01 mm, respectively. GTP and UTP were also used as energy sources. The enzyme activity was inhibited by phosphate anions and by various sulfhydryl reagents. Unlike the enzyme from mammalian tissues, the E. coli B enzyme was not inhibited by α-alkyl analogues of methionine. The enzyme was feedback inhibited by reduced glutathione, although oxidized glutathione had no inhibitory effect.     

Altered regulation of phosphatidylinositol 3-kinase signaling in cathepsin D-deficient brain

Cathepsin D (CD) is an essential lysosomal protease and mice lacking this enzyme exhibit neuropathology similar to that observed in brains of patients with neuronal ceroid lipofuscinosces (NCL/Batten disease), a group of autosomal recessive pediatric neurodegenerative diseases. CD-deficient (CD-/-) brains exhibit a dramatic induction of autophagic stress as defined by the aberrant accumulation of autophagosomes, which is concomitant with markers of apoptosis. However, the signaling abnormalities which lead to CD deficiency-induced neurodegeneration are poorly defined. Since phosphatidylinositol-3 kinase (PI3-K) is known to regulate both apoptosis and autophagy, PI3-K-mediated signaling events were assessed in CD-/- brain at P14 and P25-26. Compared to WT littermate controls, CD-/- cortical neurons exhibited a widespread decrease in phosphorylation of Akt (inactivation) and GSK3beta (disinhibition) at P25-26, while levels of total Akt and GSK3beta remained unchanged. This P25-26-specific decrease in phosphorylation of Akt and GSK-3beta in CD-/- brain coincided temporally with markers of apoptosis but followed the induction of autophagic stress observed at both P14 and P25-26. In addition, levels and/or activation of mTOR and Beclin were not affected by CD deficiency, suggesting that the accumulation of autophagosomes is not due to an increased synthesis of autophagosomes but rather from an inhibition of autophagosome recycling, due most likely to a compromise in lysosome function. Together these observations indicate a pronounced decrease in pro-survival PI3-K signaling in CD-/- brain that may contribute to autophagic stress-induced and apoptotic neuropathology.     

Leaf-rust resistance in rye (<Emphasis Type="Italic">Secale cereale</Emphasis> L.). 2. Genetic analysis and mapping of resistance genes <Emphasis Type="Italic">Pr3</Emphasis>, <Emphasis Type="Italic">Pr4</Emphasis>, and <Emphasis Type="Italic">Pr5</Emphasis>

Three dominant resistance genes, Pr3, Pr4, and Pr5, were identified by genetic analysis of resistance to leaf rust in rye (Puccinia recondita f. sp. secalis). Each of the three genes confers resistance to a broad scale of single-pustule isolates (SPIs), but differences could be observed for specific Pr gene/SPI combinations. Resistance conferred by the three genes was effective in both detached-leaf tests carried out on seedlings and in field tests of adult plants. Molecular marker analysis mapped Pr3 to the centromeric region of rye chromosome arm 1RS, whereas Pr4 and Pr5 were assigned to the centromeric region of 1RL. Chromosomal localization and reaction patterns to specific SPIs provide evidence that the three Pr genes represent distinct and novel leaf-rust resistance genes in rye. The contributions of these genes to resistance breeding in rye and wheat are discussed.The authors dedicate this paper to Prof. Dr. H.H. Geiger, University of Hohenheim, on the occasion of his 65th birthday.An erratum to this article can be found at     

Leaf-rust resistance in rye (<Emphasis Type="Italic">Secale cereale</Emphasis> L.). 2. Genetic analysis and mapping of resistance genes <Emphasis Type="Italic">Pr3</Emphasis>, <Emphasis Type="Italic">Pr4</Emphasis>, and <Emphasis Type="Italic">Pr5</Emphasis>

The conventional way to drive modifications in old forest tree seed orchards is to establish progeny trials involving each parent tree and then evaluate its contribution to the performance of the progeny by estimating its general and specific combining ability (GCA and SCA). In this work, we successfully applied an alternative parent selection tactic based on paternity testing of superior offspring derived from a hybrid seed orchard established with a single Eucalyptus grandis seed parents and six E. urophylla pollen parents. A battery of 14 microsatellite markers was used to carry out parentage tests of 256 progeny individuals including two independent samples of selected trees and one control unselected sample, all derived from 6-year-old forest stands in eastern Brazil. Paternity determination was carried out for all progeny individuals by a sequential paternity exclusion procedure. Exclusion was declared only when the obligatory paternal allele in the progeny tree was not present in the alleged parent tree for at least four independent markers to avoid false exclusions due to mutation or null alleles. After maternity checks to identify seed mixtures and selfed individuals, the paternity tests revealed that approximately 29% of the offspring was sired by pollen parents outside the orchard. No selfed progeny were found in the selected samples. Three pollen parents were found to have sired essentially all of the offspring in the samples of selected and non-selected progeny individuals. One of these three parents sired significantly more selected progeny than unselected ones (P0.0002 in a Fisher exact test). Based on these results, low-reproductive-successful parents were culled from the orchard, and management procedures were adopted to minimize external pollen contamination. A significant difference (P<0.01) in mean annual increment was observed between forest stands produced with seed from the orchard before and after selection of parents and revitalization of the orchard. An average realized gain of 24.3% in volume growth was obtained from the selection of parents as measured in forest stands at age 2–4 years. The marker-assisted tree-breeding tactic presented herein efficiently identified top parents in a seed orchard and resulted in an improved seed variety. It should be applicable for rapidly improving the output quality of seed orchards, especially when an emergency demand for improved seed is faced by the breeder.Communicated by D.B. Neale     

Uteroglobin promoter-targeted c-MYC expression in transgenic mice cause hyperplasia of Clara cells and malignant transformation of T-lymphoblasts and tubular epithelial cells

To investigate the influence of the proto-oncogene c-MYC on tumor development in different epithelial tissues which secrete Clara Cell Secretory Protein (uteroglobin, UG), transgenic mouse lines were established expressing the human c-MYC proto-oncogene under the control of the rabbit UG-promoter. These mice expressed the c-MYC transgene in Clara cells and other UG expressing tissues like uterus and prostate. In the bronchioalveolar epithelium of the lung hyperplasias developed originating from Clara cells. Surprisingly, transgenics most frequently developed T-lymphoblastic lymphomas, a polycystic kidney phenotype and renal cell carcinoma derived from tubular epithelial cells, which are both tissues that had so far not been known to express UG. Immunohistological studies in UG/MYC transgenics and in a transgenic line (UG/eGFP) expressing Green Fluorescent Protein confirmed that the uteroglobin promoter is not only active in Clara cells, but also in tubular epithelial cells of the kidney and in lymphatic tissue. The UG/MYC transgenics will be useful to investigate the biochemical mechanisms underlying the development of carcinomas and the oncogenic properties of c-MYC in epithelial cells of various tissues.