Gibberellins and the break of bud dormancy in virus-infected stem cuttings ofEuphorbia pulcherrima

Summary Break in bud dormancy in virus-infected stem cuttings ofEuphorbia pulcherrima occurs because of the higher quantity of gibberellins present in them than in healthy cuttings in the dormant period of the plant.     

Gibberellins and the break of bud dormancy in virus-infected stem cuttings of Euphorbia pulcherrima.

Break in bud dormancy in virus-infected stem cuttings of Euphorbia pulcherrima occurs because of the higher quantity of gibberellins present in them than in healthy cuttings in the dormant period of the plant.     

Role of kinetin in the dormancy ofCercis siliquastrum seeds

Summary Studies conducted onCercis siliquastrum seeds treated with kinetin confirm that this hormone does not interrupt dormancy in either whole seeds or those decoated at the radical pole. Seeds totally decoated or decoated at the cotyledon pole only demonstrated atypical germinations linked to cotyledon growth, permitting the embryo to escape the inhibitory action present in the endosperm; this does not occur when the cotyledon surface is experimentally reduced.This investigation was supported by the Italian National Research Council (C.N.R.) Project Biology of Reproduction.     

IAA oxidase activity in relation to adventitious root formation on stem cuttings of some forest tree species

Summary IAA oxixase activity was very high in stem cuttings ofSalix tetrasperma andPopulus robusta, which rooted profusely, less in stem cuttings ofHibiscus rosa sinensis which rooted less, and insignificant in those ofEucalyptus citriodora which did not root at all. Protein(s) extracted from the stem cuttings ofE. citriodora inhibited the activity of IAA oxidase as well as root formation on hypocotyl cuttings ofPhaseolus mungo. The possibility of involvement of IAA oxidase activity in the process of adventitious root formation is discussed.The research has been financed by a grant from U.S. Department of Agriculture.     

Dichloropyrimidines: Specific inhibitors of virus growth

Summary Dichloropyrimidines can be considered as a new group of antiviral substances having a common spectrum of inhibitory action.This work has been supported by a grant of Consiglio Nazionale delle Ricerche, Rome (Italy).     

Role of Chk1 in the differentiation program of hematopoietic stem cells

Hematopoietic stem cells (HSC) isolated from umbilical cord blood (UCB) were treated with ionizing radiation (IR) and sensitivity and IR induced checkpoints activation were investigated. No difference in the sensitivity and in the activation of DNA damage pathways was observed between CD133+ HSC and cells derived from them after ex vivo expansion. Chk1 protein was very low in freshly isolated CD133+ cells, and undetectable in ex vivo expanded UCB CD133+ cells. Chk1 was expressed only on day 3 of the ex vivo expansion. This pattern of Chk1 expression was corroborated in CD133+ cells isolated from peripheral blood apheresis collected from an healthy donor. Treatment with a specific Chk1 inhibitor resulted in a strong reduction in the percentage of myeloid precursors (CD33+) and an increase in the percentage of lymphoid precursors (CD38+) compared to untreated cells, suggesting a possible role for Chk1 in the differentiation program of UCB CD133+ HSC.     

Role of sex pheromone,and its insignificance for heterosexual and homosexual behaviour of larch bud moth

Zusammenfassung Das Geschlechtspheromon des LärchenwicklersZeiraphera diniana wird in einer Drüse des Weibchens an der Basis des Ovipositors produziert und scheint mittrans-11-Tetradecenylacetat identisch zu sein. Das Pheromon ist ausschliesslich Lockstoff mit Distanzwirkung und ist für die Kopulation bedeutungslos. Diese wird unter bestimmten Umweltsbedingungen durch rein optische Stimuli ausgelöst. Da die Männchen nicht streng zwischen den Geschlechtern unterscheiden können, kommen homosexuelle Kopulationen vor.

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Contribution Nr. 47 of the research team for the investigation of the population dynamics of the larch bud moth. The reserch was aided by a grant of the Swiss National Fonds for Scientific Research.     

Genetic control of dormancy in the potato cyst-nematode

Summary Matings of early-hatched parents of the potato cyst-nematode:H. rostochiensis, gave F₁ which hatched early-late-hatched parents gave progeny which showed dormancy, the extent fo which was in most instances determined by the parents' time of hatching. It is suggested that dormancy is genetically controlled.     

Role of AGC kinases in plant growth and stress responses

AGC kinases are important regulators of cell growth, metabolism, division, and survival in mammalian systems. Mutation or deregulation of members of this family of protein kinases contribute to the pathogenesis of many human diseases, including cancer and diabetes. Although AGC kinases are conserved in the plant kingdom, little is known about their molecular functions and targets. Some of the best-studied plant AGC kinases mediate auxin signaling and are thereby involved in the regulation of growth and morphogenesis. Furthermore, certain members are regulated by lipid-derived signals via the 3-phosphoinositide-dependent kinase 1 (PDK1) and the kinase target of rapamycin (TOR), similar to its animal counterparts. In this review, we discuss recent findings on plant AGC kinases that unravel important roles in the regulation of plant growth, immunity and cell death, and connections to stress-induced mitogen-activated protein kinase signaling cascades.     

Accumulation of ribonucleoprotein structures in chronically virus-infected cells

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Compartmentalized growth of hemopoietic stem cells within mouse Friend leukemic spleens

Summary A dose of 4000 rads (r) to the central portion of mouse spleens followed by Friend erythroleukemic virus infection created independent compartments where hemopoietic stem cells exhibited distinct growth kinetics. Rather than suggesting autonomous proliferation, the stem cell kinetics were indicative of the control excercised by the local microenvironment upon stem cell growth within each compartment.Acknowledgments. This work was supported in part by a grant (014077) from the American Medical Association Eduation and research Foundation, Chicago, Illinois. We also wish to thank Priscilla Brown and Peter Brown for their expertise and patience in preparing the photograph for this report.     

Role of fungal statling growth products in inter-specific competition among phylloplane fungi

Summary The effect of fungal staling growth products on leaf-inhabiting microfungi, with special reference to a leaf spot pathogenPestalotiopsis funerea Desm. ofEucalyptus globulus Labill. was studied. Results depict that antibiotics produced by competing microfungi caused the phenomenon of mycostasis on the leaf surfaces.Acknowledgments. I would like to express my thanks to Professor R.S. Dwivedi for his encouragement and to CSIR (Indian Govt.) for financial assistance.     

Role of p75 neurotrophin receptor in stem cell biology: more than just a marker

p75^NTR, the common receptor for both neurotrophins and proneurotrophins, has been widely studied because of its role in many tissues, including the nervous system. More recently, a close relationship between p75^NTR expression and pluripotency has been described. p75^NTR was shown to be expressed in various types of stem cells and has been used to prospectively isolate stem cells with different degrees of potency. Here, we give an overview of the current knowledge on p75^NTR in stem cells, ranging from embryonic to adult stem cells, and cancer stem cells. In an attempt to address its potential role in the control of stem cell biology, the molecular mechanisms underlying p75^NTR signaling in different models are also highlighted. p75^NTR-mediated functions include survival, apoptosis, migration, and differentiation, and depend on cell type, (pro)neurotrophin binding, interacting transmembrane co-receptors expression, intracellular adaptor molecule availability, and post-translational modifications, such as regulated proteolytic processing. It is therefore conceivable that p75^NTR can modulate cell-fate decisions through its highly ramified signaling pathways. Thus, elucidating the potential implications of p75^NTR activity as well as the underlying molecular mechanisms of p75^NTR will shed new light on the biology of both normal and cancer stem cells.     

Response of friend virus-infected bone marrow cells to erythropoietin in vitro

Zusammenfassung Erythropoietin stimuliert in vitro die Aufnahme von Fe⁵⁹ in normale Knochenmarkzellen der Maus, nicht aber in Knochenmarkzellen polycythämischer Tiere.     

A paradoxical effect of 2,4-dinitrophenol in stimulating the rooting of hypocotyl cuttings ofPhaseolus mungo

Summary 2,4-dinitrophenol enhanced root formation on dark-grown hypocotyl cuttings ofPhaseolus mungo. This effect is probably related to uncoupling of oxidative phosphorylation and not through IAA-metabolism as is evident from studies with respiratory inhibitors (Cd²⁺) and non-phenolic uncouplers of oxidative phosphorylation (arsenate).The research has been financed by a grant from United States Department of Agriculture.     

Hepatocyte growth factor-mediated attraction of mesenchymal stem cells for apoptotic neuronal and cardiomyocytic cells

Human bone marrow-derived mesenchymal stem cells (MSC) home to injured tissues and have regenerative capacity. In this study, we have investigated in vitro the influence of apoptotic and necrotic cell death, thus distinct types of tissue damage, on MSC migration. Concordant with an increased overall motility, MSC migrated towards apoptotic, but not vital or necrotic neuronal and cardiac cells. Hepatocyte growth factor (HGF) was expressed by the apoptotic cells only. MSC, in contrast, revealed expression of the HGF-receptor, c-Met. Blocking HGF bioactivity resulted in significant reduction of MSC migration. Moreover, recombinant HGF attracted MSC in a dose-dependent manner. Thus, apoptosis initiates chemoattraction of MSC via the HGF/c-Met axis, thereby linking tissue damage to the recruitment of cells with regenerative potential.