Perspectieven van precisiebemesting van organische mest in de biologische landbouw

Met behulp van het tweedimensionale model FUSSIM2 zijn berekeningen gemaakt om de perspectieven van precisiebemesting voor de biologische landbouw te verkennen. De berekeningen richtten zich op stikstof. Organische mest werd volvelds oppervlakkig (0-15 cm onder maaiveld), volvelds diep (15-30 cm onder maaiveld), en oppervlakkig dicht bij de plant geplaatst. De laatste behandeling bewerkstelligde een meeropname van 5-10 kg/ha, een gering maar relevant verschil. Precisiebemesting van organische mest isdaarom ook voor de biologische landbouw aan te bevelen

Oligodendrocyte HCN2 channels regulate myelin sheath length

Oligodendrocytes generate myelin sheaths vital for the formation, health and function of the central nervous system (CNS). Myelin sheath length is a key property that determines axonal conduction velocity and is known to be variable across the CNS. Myelin sheath length can be modified by neuronal activity, suggesting that dynamic regulation of sheath length might contribute to the functional plasticity of neural circuits. Although the mechanisms that establish and refine myelin sheath length are important determinants of brain function, our understanding of these remains limited. In recent years, the membranes of myelin sheaths have been increasingly recognised to contain ion channels and transporters that are associated with specific important oligodendrocyte functions, including metabolic support of axons and the regulation of ion homeostasis, but none have been shown to influence sheath architecture. In this study, we determined that hyperpolarisation-activated, cyclic nucleotide-gated (HCN) channels, typically associated with neuronal and cardiac excitability, regulate myelin sheath length. Using both in vivo and in vitro approaches, we show that oligodendrocytes abundantly express functional, predominantly HCN2 subunit-containing channels. These HCN channels retain key pharmacological and biophysical features and regulate the resting membrane potential of myelinating oligodendrocytes. Further, reduction of their function via pharmacological blockade or generation of transgenic mice with two independent oligodendrocyte-specific HCN2 knock out strategies reduced myelin sheath length. We conclude that HCN2 channels are key determinants of myelin sheath length in the CNS

Locomotor recovery following contusive spinal cord injury does not require oligodendrocyte remyelination

The contribution of oligodendrocytes to remyelination in functional recovery after spinal cord injury is not fully understood. Here, the authors show that oligodendrocyte progenitor cell differentiation is not required for functional recovery after spinal cord injury in mice

Differentiation of human adipose-derived stem cells into neuron/motoneuron-like cells for cell replacement therapy of spinal cord injury

Human adipose-derived stem cells (hADSCs) are increasingly presumed to be a prospective stem cell source for cell replacement therapy in various degenerative and/or traumatic diseases. The potential of trans-differentiating hADSCs into motor neuron cells indisputably provides an alternative way for spinal cord injury (SCI) treatment. In the present study, a stepwise and efficient hADSC trans-differentiation protocol with retinoic acid (RA), sonic hedgehog (SHH), and neurotrophic factors were developed. With this protocol hADSCs could be converted into electrophysiologically active motoneuron-like cells (hADSC-MNs), which expressed both a cohort of pan neuronal markers and motor neuron specific markers. Moreover, after being primed for neuronal differentiation with RA/SHH, hADSCs were transplanted into SCI mouse model and they survived, migrated, and integrated into injured site and led to partial functional recovery of SCI mice. When ablating the transplanted hADSC-MNs harboring HSV-TK-mCherry overexpression system with antivirial Ganciclovir (GCV), functional relapse was detected by motor-evoked potential (MEP) and BMS assays, implying that transplanted hADSC-MNs participated in rebuilding the neural circuits, which was further confirmed by retrograde neuronal tracing system (WGA). GFP-labeled hADSC-MNs were subjected to whole-cell patch-clamp recording in acute spinal cord slice preparation and both action potentials and synaptic activities were recorded, which further confirmed that those pre-conditioned hADSCs indeed became functionally active neurons in vivo. As well, transplanted hADSC-MNs largely prevented the formation of injury-induced cavities and exerted obvious immune-suppression effect as revealed by preventing astrocyte reactivation and favoring the secretion of a spectrum of anti-inflammatory cytokines and chemokines. Our work suggests that hADSCs can be readily transformed into MNs in vitro, and stay viable in spinal cord of the SCI mouse and exert multi-therapeutic effects by rebuilding the broken circuitry and optimizing the microenvironment through immunosuppression

Modelstudie naar het effect van onbemeste stroken op de stikstofuitspoeling naar grond- en oppervlaktewater

Door middel van modelberekeningen is het effect van onbemeste bufferstroken op de uitspoeling van anorganisch stikstof naar grond- en oppervlaktewater onderzocht voor onbeweide grasland-percelen

Perspectieven van precisiebemesting van organische mest in de biologische landbouw

Met behulp van het twee-dimensionale model FUSSIM2 zijn berekeningen gemaakt om de perspectieven van precisiebemesting voor de biologische landbouw te verkennen. De berekeningen richtten zich op stikstof. Organische mest werd volvelds oppervlakkig (0-15 cm onder maaiveld), volvelds diep (15-30 cm onder maaiveld) en opervlakkig dicht bij de plant geplaatst. De laatste behandeling bwerkstelligde een meeropname van 5-10 kg ha-1, een gering maar relevant verschil. Precisiebemesting van organische mest is daarom ook voor de biologische landbouw aan te bevelen