Gadjah Mada University

About: Gadjah Mada University is a education organization based out in Yogyakarta, Indonesia. It is known for research contribution in the topics: Population & Adsorption. The organization has 17307 authors who have published 21389 publications receiving 116561 citations. The organization is also known as: University of Gajah Mada & Universitas Gadjah Mada.

Ragulator and GATOR1 complexes promote fission yeast growth by attenuating TOR complex 1 through Rag GTPases

Abstract: TOR complex 1 (TORC1) is an evolutionarily conserved protein kinase complex that promotes cellular macromolecular synthesis and suppresses autophagy. Amino-acid-induced activation of mammalian TORC1 is initiated by its recruitment to the RagA/B-RagC/D GTPase heterodimer, which is anchored to lysosomal membranes through the Ragulator complex. We have identified in the model organism Schizosaccharomyces pombe a Ragulator-like complex that tethers the Gtr1-Gtr2 Rag heterodimer to the membranes of vacuoles, the lysosome equivalent in yeasts. Unexpectedly, the Ragulator-Rag complex is not required for the vacuolar targeting of TORC1, but the complex plays a crucial role in attenuating TORC1 activity independently of the Tsc1-Tsc2 complex, a known negative regulator of TORC1 signaling. The GATOR1 complex, which functions as Gtr1 GAP, is essential for the TORC1 attenuation by the Ragulator-Rag complex, suggesting that Gtr1GDP-Gtr2 on vacuolar membranes moderates TORC1 signaling for optimal cellular response to nutrients.

Chitosan-Based Polyion Multilayer Coating on NPK Fertilizer as Controlled Released Fertilizer

Abstract: Low efficiency of conventional fertilizer (quick release fertilizer) application in agricultural sectors has caused environmental pollution and health problems. A method to overcome the drawback of the conventional fertilizer is by controlled release fertilizer (CRF) preparation. CRF is expected to be able to fulfil the nutrient demand of targeted plants. The objective of this research is to prepare CRF by coating NPK fertilizer with multilayer chitosan-polyanion using alginate, pectin, and sodium tripolyphosphate (TPP). In addition, the effect of the layer arrangement modification of material on the rate of nitrogen release was also studied. The mechanical strength of coated fertilizer was analysed by compressive stress test and the properties of the fertilizer coating was observed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The nitrogen release study shows that multilayer of chitosan-alginate (CA)5, chitosan-pectin (CP)5, and chitosan-TPP (CT)5 as coating material was able to increase the compressive stress and decrease the nitrogen release of coated fertilizer. These results are supported by the FTIR analysis which exhibits the formation of ionic interaction between amine group of chitosan and carboxyl group of alginate in chitosan-alginate (CA)5 layer, carboxyl group of pectin in chitosan-pectin (CP)5 layer, and phosphate of TPP in chitosan-TPP (CT)5 layer. On the other hand, the modification of the arrangement of chitosan-alginate layers showed that the fertilizer with the alternating layer arrangement (CA)5 was able to optimally increase the compressive strength. The mathematical model for the nitrogen release of coated fertilizer is also prepared and simulated with the MATLAB software. The simulation results showed that the nitrogen release of coated fertilizer followed the proposed diffusion mechanism. The obtained diffusivity coefficient value in the layer of chitosan-alginate (CA)5 is 2.0933 × 10−6 cm2/s, 2.5606 × 10−6 cm2/s in chitosan-TPP (CT)5 layer, and 3.7256 × 10−6 cm2/s in chitosan-pectin (CP)5 layer.

The Influence of Thidiazuron on Direct Somatic Embryo Formation from Various Types of Explant in Phalaenopsis amabilis (L.) Blume Orchid

Abstract: Phalaenopsis amabilis is an important national flower of Indonesia as a parent for orchid breeding, so that needs a good strategy to produce high number of plants. The objective of this research is to analyze the use of thidiazuron (TDZ) for producing high number of plantlets, through directly induction of somatic embryos (SEs) from various explants. The method was used 20 each of protocorms, leaves, stems and roots as explants. The explants were dissected transversely, then put on various culture media: New Phalaenopsis (NP) and NP + (1, 2, 3) mgL−1 TDZ. Cultures were maintained at 25°C with continous white light. The formation of SEs was observed every week for 8 weeks. The results showed that SEs formation increased inline with the addition of TDZ concentration to the NP medium, for both velocity and amount of SEs formation. In NP0, SEs were formed at (26.07 ± 0.73) days after inoculation of protocorm, whereas on NP + (1, 2, and 3 mgL−1) TDZ, SEs were formed at (17.85 ± 0.67) days, (15 ± 0.64) days, and (11 ± 0.64) days, respectively. All types of explants formed SEs on NP + TDZ (1–3 mgL−1), whereas only 14 of 20 protocorms produced SEs (70%), and 8 of 20 stems formed SEs (40%) in NP0. In roots, SEs was formed on NP + 2 mgL−1 TDZ and NP + 3 mgL−1 TDZ. For stems, the highest amount of SEs (28.25 ± 1.07) was reached on NP + 3 mgL−1 TDZ, followed by protocorm (23.30 ± 1.13) SEs and roots (8.25 ± 0.68) SEs. In contrast, in NP0, the amount of SEs was very low (1.25 ± 0.46) from stem and (1.50 ± 0.65) from protocorms, there was no evidence of SEs formation in the leaves and roots.