Základy půdní úrodnosti

Zvyšování půdní úrodnosti bylo pro průkopníky ekologického zemědělství základem veškerého jejich úsilí. Přesto zachování úrodné půdy mnohdy nebyla věnována dostatečná pozornost. Ekologické zemědělství je však na přirozené půdní úrodnosti závislé. Oslabená a poškozená půda nám nemůže poskytnout to, co od ní očekáváme. Udržet úrodnost půdy vyžaduje velkou péči. Předkládaná brožura ukazuje půdní úrodnost z různých úhlů pohledu. Naším záměrem však nebylo vytvořit obecně platný „návod k použití“. Informace mají být mnohem spíše podnětem k tomu, aby se o vztahu člověka k půdě smýšlelo jinak a aby se tento vztah utvářel ve prospěch budoucnosti

Verhandlungen der Physikalischen Gesellschaft zu Berlin.

List of members in v. 5-17.Vol. 15, no. 1: Bericht über die Feier des 50 jährigen bestehens am 4. januar 1896.Editors: 1882 (no editor given); 1883-85, F. Neesen; 1886-88, E. Roschatius (1888 with A. König); 1889-98, A. König.List of members in v. 5-17.Vol. 15, no. 1: Bericht über die Feier des 50 jährigen bestehens am 4. januar 1896.Mode of access: Internet.Vols. 1-4, 1882-85, and the first 10 nos. of v. 5, 1886 were issued with Fortschritte der Physik. Vol. 11, 1892, was issued with Annalen der Physik und Chemie, hrsg. von Wiedemann, neue folge, bd. 45-48, and was also issued separately

Genome amplification and cellular senescence are hallmarks of human placenta development

Genome amplification and cellular senescence are commonly associated with pathological processes. While physiological roles for polyploidization and senescence have been described in mouse development, controversy exists over their significance in humans. Here, we describe tetraploidization and senescence as phenomena of normal human placenta development. During pregnancy, placental extravillous trophoblasts (EVTs) invade the pregnant endometrium, termed decidua, to establish an adapted microenvironment required for the developing embryo. This process is critically dependent on continuous cell proliferation and differentiation, which is thought to follow the classical model of cell cycle arrest prior to terminal differentiation. Strikingly, flow cytometry and DNAseq revealed that EVT formation is accompanied with a genome-wide polyploidization, independent of mitotic cycles. DNA replication in these cells was analysed by a fluorescent cell-cycle indicator reporter system, cell cycle marker expression and EdU incorporation. Upon invasion into the decidua, EVTs widely lose their replicative potential and enter a senescent state characterized by high senescence-associated (SA) beta-galactosidase activity, induction of a SA secretory phenotype as well as typical metabolic alterations. Furthermore, we show that the shift from endocycle-dependent genome amplification to growth arrest is disturbed in androgenic complete hydatidiform moles (CHM), a hyperplastic pregnancy disorder associated with increased risk of developing choriocarinoma. Senescence is decreased in CHM-EVTs, accompanied by exacerbated endoreduplication and hyperploidy. We propose induction of cellular senescence as a ploidy-limiting mechanism during normal human placentation and unravel a link between excessive polyploidization and reduced senescence in CHM.Funding Agencies|Austrian Science Fund [P-25187, P-28417, P-31470]; Herzfeldersche Familienstiftung [00685]; Jubilaumsfonds Austrian National Bank [16517]; European Fund for Regional Development (EFRE) [IWB2020]; Federal State of Upper Austria; Stanford Child Health Research Institute</p