Identification and action of juvenile hormone III from sexually mature alate females of the red imported fire ant,Solenopsis invicta

Analysis of extracts of hemolymph obtained from sexually mature alate females of Solenopsis invicta from monogyne colonies resulted in identification of juvenile hormone III (JH III). The average amount of JH III was 0.32±0.04 pmol/μmolof hemolymph. Topical application of 0.038 pmol of JH III was sufficient to stimulate alates to shed their wings in the presence of the queen. The time in which alates were induced to dealate decreased linearly with increasing concentrations of JH III from 0.038 to 3.8 pmol. However, higher JH III concentrations deviated from linearity and did not reach dealation times comparable with those that occur after mating flights. Thus, it appears that the mechanism of dealation that occurs when female alates are out of the influence of their queen is different from the one associated with mating flights. Application of 0.42 μmol of precocene II inhibited dealation of alates in queenless colonies. However, this inhibition was reversed after applying 38 pmol JH III to precocene-treated alates. The sizes of corpora allata (CA) from sexuals treated with JH III did not differ from those of controls. However, the sizes of CA were reduced in alates treated with precocene II. The results indicated that JH was important to dealation.     

Endogenous levels of free and conjugated forms of auxin, cytokinins and abscisic acid during seed development in Douglas fir

Endogenous levels of free and conjugated forms of three classes of planthormones were quantified at various stages of megagametophyte development inDouglas fir. Megagametophytes were excised weekly from 8–16 weeks pastpollination (WPP), a period encompassing the central cell to the earlymaturation stage of seed development. The hormones indole-3 acetic acid (IAA),indole-3-aspartate (IAAsp), zeatin (Z), zeatin riboside (ZR), isopentenyladenine(iP), isopentenyladenosine (iPA), abscisic acid (ABA) and abscisic acid glucoseester (ABA-GE) were extracted, purified, fractionated by high- performanceliquid chromatography (HPLC), and then quantified using an enzyme-linkedimmunosorbent assay (ELISA) method. Z levels ranged from 0–25ng/g dry weight (DW) and were highest in megagametophytes at thecentral cell stage (8 WPP). During embryogenesis, Z levels peakedduring week 13. In contrast, the ZR conjugate was not detected over the periodstudied. The iP content of megagametophytes increased at 10 and 13WPP, while the iPA concentration increased at 13 WPP.Prior to fertilisation, IAA was highest in megagametophytes at 9WPP. During embryogenesis, the major IAA accumulations occurred at11, 13 and 15 WPP, the concentration ranging from 0–0.43g/g DW. IAAsp concentrations reached their highest level duringembryogenesis at 14 WPP. ABA content increased at 11 and 13WPP, with a concentration range of 0.1–13 g/gDW. In contrast, ABA-GE levels were relatively constant over the 9-weekperiod analyzed. The endogenous levels of plant hormones varied withmegagametophyte development and were associated with morphological changes.     

Brassinosteroid-Mediated Stress Responses

Brassinosteroids (BRs) are a group of naturally occurring plant steroidal compounds with wide-ranging biological activity that offer the unique possibility of increasing crop yields through both changing plant metabolism and protecting plants from environmental stresses. In recent years, genetic and biochemical studies have established an essential role for BRs in plant development, and on this basis BRs have been given the stature of a phytohormone. A remarkable feature of BRs is their potential to increase resistance in plants to a wide spectrum of stresses, such as low and high temperatures, drought, high salt, and pathogen attack. Despite this, only a few studies aimed at understanding the mechanism by which BRs promote stress resistance have been undertaken. Studies of the BR signaling pathway and BR gene-regulating properties indicate that there is cross-talk between BRs and other hormones, including those with established roles in plant defense responses such as abscisic acid, jasmonic acid, and ethylene. Recent studies aimed at understanding how BRs modulate stress responses suggest that complex molecular changes underlie BR-induced stress tolerance in plants. Analyses of these changes should generate exciting results in the future and clarify whether the ability of BRs to increase plant resistance to a range of stresses lies in the complex interactions of BRs with other hormones. Future studies should also elucidate if BRI1, an essential component of the BR receptor, directly participates in stress response signaling through interactions with ligands and proteins involved in plant defense responses.     

DNA slows dissociation of progesterone receptor-steroid ligand complexes

Steroid ligands are known to affect the interactions of their respective receptors with DNA. In the present study, the possibility of DNA interference in progesterone receptor-ligand interactions was investigated. An oligonucleotide containing a hormone response element (HRE) was shown to decrease the dissociation rate of complexes of [3H]progesterone or [3H]16alpha,17alpha-cycloalkanoprogesterones with PRs from rabbit and rat uterine cytosol. The extent to which the oligonucleotide affected the dissociation constant varied from about 4- to 1.5-fold depending on the ligand structure and was ranked in the following order: progesterone>16alpha,17alpha-cyclopropanoprogesterone approximately 16alpha,17alpha-cyclopentanoprogesterone>/=16alpha,17alpha-cyclohex-2'-enoprogesterone approximately 6alpha-methyl-16alpha,17alpha-cyclohexanoprogesterone>/=16alpha,17alpha-cyclohexanoprogesterone. The control oligonucleotide lacking HRE had a weak effect, if any, on the dissociation kinetics. No influence of the HRE-containing oligonucleotide on the equilibrium binding of ligands to PR was observed. The results suggest that the DNA partner affects binding of PR to its ligand.     

Energy requirements of the red kangaroo (<Emphasis Type="Italic">Macropus rufus</Emphasis>): impacts of age,growth and body size in a large desert-dwelling herbivore.

Generally, young growing mammals have resting metabolic rates (RMRs) that are proportionally greater than those of adult animals. This is seen in the red kangaroo (Macropus rufus), a large (>20 kg) herbivorous marsupial common to arid and semi-arid inland Australia. Juvenile red kangaroos have RMRs 1.5–1.6 times those expected for adult marsupials of an equivalent body mass. When fed high-quality chopped lucerne hay, young-at-foot (YAF) kangaroos, which have permanently left the mother's pouch but are still sucking, and recently weaned red kangaroos had digestible energy intakes of 641±27 kJ kg^–0.75 day^–1 and 677±26 kJ kg^–0.75 day^–1, respectively, significantly higher than the 385±37 kJ kg^–0.75 day^–1 ingested by mature, non-lactating females. However, YAF and weaned red kangaroos had maintenance energy requirements (MERs) that were not significantly higher than those of mature, non-lactating females, the values ranging between 384 kJ kg^–0.75 day^–1 and 390 kJ kg^–0.75 day^–1 digestible energy. Importantly, the MER of mature female red kangaroos was 84% of that previously reported for similarly sized, but still growing, male red kangaroos. Growth was the main factor affecting the proportionally higher energy requirements of the juvenile red kangaroos relative to non-reproductive mature females. On a good quality diet, juvenile red kangaroos from permanent pouch exit until shortly after weaning (ca. 220–400 days) had average growth rates of 55 g body mass day^–1. At this level of growth, juveniles had total daily digestible energy requirements (i.e. MER plus growth energy requirements) that were 1.7–1.8 times the MER of mature, non-reproductive females. Our data suggest that the proportionally higher RMR of juvenile red kangaroos is largely explained by the additional energy needed for growth. Energy contents of the tissue gained by the YAF and weaned red kangaroos during growth were estimated to be 5.3 kJ g^–1, within the range found for most young growing mammals.Abbreviations BMR basal metabolic rate - DEI digestible energy intake - MER maintenance energy requirement - MER_g maintenance plus growth energy requirement - PPE permanent pouch exit - RMR resting metabolic rate - YAF young-at-foot Communicated by I.D. Hume     

Tumour biology of a breast cancer at least partly reflects the biology of the tissue/epithelial cell of origin at the time of initiation - a hypothesis

A hypothesis is presented suggesting that initiation of breast epithelial cell freezes the cell at least partly according to the development/differention of cell at the time of initiation. Tumour biology will mimic the physiology of normal cell development at the time of initiation and this is preserved at least partly onwards. Also preferentially, tumours will develop from the cell type that is proliferating at the time of initiation. This may explain the overrepresentation of different types of histology in breast cancer in relation to age of the woman. The development of each tumour may follow at least partly a distinct pathway of evolution.     

Characterization of apelin, the ligand for the APJ receptor

The apelin peptide was recently discovered and demonstrated to be the endogenous ligand for the G protein-coupled receptor, APJ. A search of the GenBank databases retrieved a rat expressed sequence tag partially encoding the preproapelin sequence. The GenBank search also revealed a human sequence on chromosome Xq25-26.1, containing the gene encoding preproapelin. We have used the rat sequence to screen a rat brain cDNA library to obtain a cDNA encoding the full-length open reading frame of rat preproapelin. This cDNA encoded a protein of 77 amino acids, sharing an identity of 82% with human preproapelin. Northern and in situ hybridization analyses revealed both human and rat apelin and APJ to be expressed in the brain and periphery. Both sequence and mRNA expression distribution analyses revealed similarities between apelin and angiotensin II, suggesting they that share related physiological roles. A synthetic apelin peptide was injected intravenously into male Wistar rats, resulting in immediate lowering of both systolic and diastolic blood pressure, which persisted for several minutes. Intraperitoneal apelin injections induced an increase in drinking behavior within the first 30 min after injection, with a return to baseline within 1 h.     

稀有鮈鲫胚后发育和幼鱼生长的初步研究

本文介绍了室养条件下稀有　鲫胚后发育与幼鱼生长的特点。稀有　鲫的胚后发育过程可分为3个阶段共11个时期,在水温24．7—31．8℃的条件下,初孵仔鱼经25—30d即可完成胚后发育。在胚后发育期间,仔鱼、稚鱼及幼鱼呈线性生长,每日增长0．52mm左右。饲养条件对生长和发育均有很大影响。在相同的饲养条件下,采于四川省汉源县、灌县及彭县的亲鱼,其后代在生长上无显著性差异。     

长白落叶松激素含量与生长的关系及在早期选择中的应用

用间接酶联免疫吸附法测定了不同季节不同种源长白落叶松激素含量。结果表明：不同季节长白落叶松的激素含量不同,速生期长白落叶松赤霉素、生长素和细胞分裂素含量高,脱落酸含量低,赤霉素／脱落酸比值大,生长缓慢期测定结果恰好相反。各类激素含量在不同种源长白落叶松间的变异显著,且与生长性状的差异密切相关。生长快的种源赤霉素,细胞分裂素含量高,脱落酸含量低,赤霉素／脱落酸之比大。生长慢的种源则相反。回归分析表明     

Dextran–estrone conjugate: synthesis and in vitro release study

A novel hormone conjugate has been prepared by a coupling reaction between modified estrone and dextran. In order to provide a suitable reactive estrone derivative for coupling with dextran and a spacer between the drug carrier and the hormone, the steroidal sex hormone was succinylated by reaction with succinic anhydride. Subsequently, the carboxylic acid terminal of succinylated estrone was further reacted with thionyl chloride to replace the hydroxy group with chlorine to make a better leaving group. The ester bond was employed as labile linkage between the hormone and the biopolymer carrier backbone so that the coupled estrogen could be released from the conjugate via ester hydrolysis. Structures of the modified estrone and dextran–estrone conjugate were determined by elemental analysis and by FTIR, ¹H and ¹³C NMR spectroscopies. The degree of substitution (D.S.) per anhydroglucose (AHG) unit was 0.33 (11.0 mol-% of estrone moieties), as calculated from the ¹H NMR spectrum. In vitro hydrolysis of the conjugate in aqueous phosphate buffer/ethanol solutions at pH 8.0 and 7.4 and 37°C released estrone was completed within a few days and followed zero-order kinetics.