Unusual Branching in the Seedlings of Lotus japonicus--Gibberellins Reveal the Nitrogen-sensitive Cell Divisions within the Pericycle on Roots

We studied the effects of several plant-growth regulators onthe induction of nodule-like structures on roots of Lotus japonicus,which has been proposed as a candidate for a leguminous plantfor molecular genetic analysis. Contrary to our expectations,the addition of gibberellin A₃ (GA₃) at concentrations of 10^-4M to 10^-4 M resulted in the formation of nodule-like structureson roots when seedlings were plated on nitrogen-free Fahraeusagar medium. GA₄ also induced such outgrowths but was less activethan GA₃. Application of an inhibitor of auxin transport, N-(1-naphthyl)-phthalamicacid (NPA) and of kinetin, which have been reported to inducepseudonodules in other legumes, had no effect on L. japonicus.Microscopic observations showed that GA₃-induced nodule-likestructures were caused by cell divisions within the pericycleon the roots. In addition, the outgrowths elicited by GA₃ couldbe completely suppressed by the addition of 15 mM potassiumnitrate or ammonium nitrate. These results show that the pericyclecells of the roots of L. japonicus are specifically sensitiveto gibberellins and that potential for cell division might bemodulated by nitrogen compounds. We also examined the effectsof ancymidol and uniconazole [S-3307; (E)-1-(4-chIorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol],two synthetic plant-growth retardants. Both compounds at 3 x10^-5 M significantly increased the number of stunted lateralroots. The unusual branching could not be counteracted by theexogenous addition of GA₃ but by 10^-6 M brassinolide. We discussthe physiological role of brassinolide in the initiation oflateral roots. (Received August 4, 1995; Accepted March 11, 1996)     

The Excessive Production of Indole-3-Acetic Acid and Its Significance in Studies of the Biosynthesis of This Regulator of Plant Growth and Development

Because of the importance of indole-3-acetic acid (IAA) in thegrowth and development of plants, extensive studies of the biosynthesisof IAA have been performed during the four decades since thediscovery of IAA as a plant hormone. The pathway for the biosynthesisof IAA in plants remains, however, to be unelucidated, eventhough studies within the past decade have revealed unexpectedaspects of such biosynthesis. By contrast, two pathways to IAAhave been characterized in bacteria at the molecular level:the indole-3-acetamide (IAM) pathway (L-tryptophan     

Peroxyoxalate chemiluminescent assay for oxidase activities based on detecting enzymatically formed hydrogen peroxide

A sensitive peroxyoxalate chemiluminescent (PO-CL) assay for activities of oxidases (uricase, choline oxidase, cholesterol oxidase and xanthine oxidase) which catalyse a formation of hydrogen peroxide was developed using 4,4′-oxalyl-bis[(trifluoromethylsulphonyl)imino]trimethylene-bis(4-methylmorpholinium)trifluoromethanesulphonate as a chemiluminogenic reagent and 2,4,6,8-tetramorpholinopyrimido[5,4-d]pyrimidine as a fluorophore. The standard curve for hydrogen peroxide was linear over the range 1 × 10^?7-1 × 10^?4 mol/L. Relative standard deviations for oxidase assays were 5.1–12.7% (n = 10). Detection limits were 1 × 10^?3 U/mL for uricase, 5 × 10^?4 U/mL for choline oxidase, 5 × 10^?3 U/mL for cholesterol oxidase and 5 × 10^?4 U/mL xanthine oxidase (sample to blank ratio, 3).     

Male emergence timing and mating success in the funnel-web spider,Agelena limbata (Araneae: Agelenidae)

Field observations on the relationship between male mating success and emergence timing in the funnel-web spider,Agelena limbata, were conducted.Agelena limbata is an annual species and adult males appear slightly earlier than adult females in July. As males deposit a copulatory plug at the female epigynum after copulation, copulation with virgin females is important to males. The number of copulations in males with virgin females, which strongly correlates with the longevity of males and the number of females that males courted, did not correlate with the emergence timing of males. Early emerged males and females were significantly larger in size than later ones, but the correlation coefficient between the emerged date and the cephalothorax width was not strong. Males that emerged earlier did not have any advantage in copulating with larger and more fecund females. Furthermore, virgin females first copulated on average 7.9 days after their final molt and the mortality rate of adult males increased after the final molt. These factors may favor the smaller degree of protandry in male emergence timing inA. limbata.     

Infection by echoviruses 1 and 8 depends on the alpha 2 subunit of human VLA-2.

Anti-VLA-2 antibodies protected HeLa cells from infection by echoviruses 1 and 8 but not from infection by other echovirus serotypes. Echoviruses 1 and 8 bound to and infected nonpermissive hamster cells transfected with the alpha 2 subunit of human VLA-2. These results indicate that the human alpha 2 subunit is critical for infection by echoviruses 1 and 8 but that other echovirus serotypes must bind receptors other than VLA-2.     

Effects of physical exercise on the elasticity and elastic components of the rat aorta

To evaluate the effects of exercise on aortic wall elasticity and elastic components, young male rats underwent various exercise regimes for 16 weeks. In the exercised rats, the aortic incremental elastic modulus decreased significantly when under physiological strain. The aortic content of elastin increased significantly and the calcium content of elastin decreased significantly in the exercised group. The accumulated data from the exercised and sedentary groups revealed that the elastin calcium content was related positively to the incremental elastic modulus. We concluded that physical exercise from an early age decreases the calcium deposit in aortic wall elastin and that this effect probably produced in the exercised rats a distensible aorta.     

Host plant conspicuousness and the distribution of eggs and larvae in the butterfly,Anthocharis scolymus (Lepidoptera: Pieridae)

We investigated how the distribution pattern of eggs and larval on the host plant, Turritus glabra, was influenced by the oviposition behavior of the pierid butterfly Anthocharis scolymus. Females searched for the host plants visually and they frequently approached taller host plants with sparse surrounding vegetation. After encountering host plants, oviposition behavior of females was independent of host plant characteristics such as height, density, and type of surrounding vegetation. A female laid eggs singly on a host plants. Most females appeared to lay their eggs regardless of the presense of eggs on the host plant. Consequently egg and larva tended to be abundant on conspicuous host plants as measured by height or relative isolation from other plants. However, overcrowding of eggs on an individual host decreased the survival rate of larvae.     

Control of trophoblast cell differentiation: Lessons from the genetics of early pregnancy loss and trophoblast neoplasia

Trophoblast cell differentiation is crucial to the morphogenesis of the placenta and thus the establishment of pregnancy and the growth and development of the embryo/fetus. In the present review, we discuss current evidence for the existence of regulatory genes crucial to trophoblast cell differentiation and placental morphogenesis. The elucidation of regulatory pathways controlling normal differentiation of trophoblast cells will facilitate the identification of sensitive junctures in the regulatory pathways leading to various developmental disorders, including those associated with the initiation of pregnancy, fetal growth retardation and gestational trophoblast disease.     

Pathological changes of myocardial cytoskeleton in cardiomyopathic hamster

Immunocytochemical investigation was performed on the cytoskeletal proteins in cardiac tissue of the cardiomyopathic hamster. Male cardiomyopathic UM-X7.1 hamsters at 180 days of age (n=8) and age- and sex-matched normal BIO-RB hamsters (n=8) were used in this study. Immunofluorescence microscopy using monoclonal antibodies against desmin, -actinin, titin, and vincullin was employed. The heart weight to body weight ratio was significantly increased in the heart of cardiomyopathic hamster compared with that of normal hamster. In cardiomyopathic hamster, the left ventricular cavity was markedly dilated. Light microscopically, hypertrophy and atrophy of myocytes and myocardial fibrosis were prominently observed in cardiomyopathic myocardium. Immunocytochemically, desmin, -actinin and titin showed the cross striations along the myofibers in normal myocardium. In contrast, in cardiomyopathic myocardium, desmin was irregularly distributed in myocytes and the amount of desmin was increased. Loss of cross striations of -actinin and titin were frequently observed. Immunofluorescence against vinculin was not significantly altered. We conclude that the alterations of cytoskeletal proteins in myocardial cells may relate to decreased myocardial function in cardiomyopathic hamster failing heart.