Fusicoccin Counteracts the Toxic Effect of Cadmium on the Growth of Maize Coleoptile Segments

The effects of cadmium (Cd; 0.1–1000 μM) and fusicoccin (FC) on growth, Cd2+ content, and membrane potential (Em) in maize coleoptile segments were studied. In addition, the Em changes and accumulation of Cd and calcium (Ca) in coleoptile segments treated with Cd2+ combined with 1 μM FC or 30 mM tetraethylammonium (TEA) chloride (K+-channel blocker) were also determined. In this study, the effects of Ca2+-channel blockers [lanthanum (La) and verapamil (Ver)] on growth and content of Cd2+ and Ca2+ in coleoptile segments were also investigated. It was found that Cd at high concentrations (100 and 1000 μM) significantly inhibited endogenous growth of coleoptile segments and simultaneously measured proton extrusion. FC combined with Cd2+ counteracted the toxic effect of Cd2+ on endogenous growth and significantly decreased Cd2+ content (not the case for Cd2+ at the highest concentration) in coleoptile segments. Addition of Cd to the control medium caused depolarization of Em, the extent of which was dependent on Cd concentration and time of treatment with Cd2+. Hyperpolarization of Em induced by FC was suppressed in the presence of Cd2+ at 1000 μM but not Cd2+ at 100 μM. It was also found that treatment of maize coleoptile segments with 30 mM TEA chloride caused hyperpolarization of Em and decreased Cd2+ content in coleoptile segments, suggesting that, in the same way as for FC, accumulation of Cd2+ was dependent on plasma membrane (PM) hyperpolarization. Similar to FC, TEA chloride also decreased Ca2+ content in coleoptile segments. La and Ver combined with Cd2+ (100 μM) significantly decreased Cd content in maize coleoptile segments, but only La completely abolished the toxic effect of Cd2+ on endogenous growth and growth in the presence of FC. Taken together, these results suggest that the mechanism by which FC counteracts the toxic effect of Cd2+ (except at 1000 μM Cd2+) on the growth of maize coleoptile segments involves both stimulation of PM H+-ATPase activity by FC as well as Cd2+-permeable, voltage-dependent Ca channels, which are blocked by FC and TEA chloride-induced PM hyperpolarization

Targeting Lysophosphatidic Acid Signaling Retards Culture-Associated Senescence of Human Marrow Stromal Cells

Marrow stromal cells (MSCs) isolated from mesenchymal tissues can propagate in vitro to some extent and differentiate into various tissue lineages to be used for cell-based therapies. Cellular senescence, which occurs readily in continual MSC culture, leads to loss of these characteristic properties, representing one of the major limitations to achieving the potential of MSCs. In this study, we investigated the effect of lysophosphatidic acid (LPA), a ubiquitous metabolite in membrane phospholipid synthesis, on the senescence program of human MSCs. We show that MSCs preferentially express the LPA receptor subtype 1, and an abrogation of the receptor engagement with the antagonistic compound Ki16425 attenuates senescence induction in continually propagated human MSCs. This anti-aging effect of Ki16425 results in extended rounds of cellular proliferation, increased clonogenic potential, and retained plasticity for osteogenic and adipogenic differentiation. Expressions of p16Ink4a, Rb, p53, and p21Cip1, which have been associated with cellular senescence, were all reduced in human MSCs by the pharmacological inhibition of LPA signaling. Disruption of this signaling pathway was accompanied by morphological changes such as cell thinning and elongation as well as actin filament deformation through decreased phosphorylation of focal adhesion kinase. Prevention of LPA receptor engagement also promoted ubiquitination-mediated c-Myc elimination in MSCs, and consequently the entry into a quiescent state, G0 phase, of the cell cycle. Collectively, these results highlight the potential of pharmacological intervention against LPA signaling for blunting senescence-associated loss of function characteristic of human MSCs

Physiological response of the retinal pigmented epithelium to 3-ns pulse laser application, in vitro and in vivo

BACKGROUND: To treat healthy retinal pigmented epithelium (RPE) with the 3-ns retinal rejuvenation therapy (2RT) laser and to investigate the subsequent wound-healing response of these cells. METHODS: Primary rat RPE cells were treated with the 2RT laser at a range of energy settings. Treated cells were fixed up to 7 days post-irradiation and assessed for expression of proteins associated with wound-healing. For in vivo treatments, eyes of Dark Agouti rats were exposed to laser and tissues collected up to 7 days post-irradiation. Isolated wholemount RPE preparations were examined for structural and protein expression changes. RESULTS: Cultured RPE cells were ablated by 2RT laser in an energy-dependent manner. In all cases, the RPE cell layer repopulated completely within 7 days. Replenishment of RPE cells was associated with expression of the heat shock protein, Hsp27, the intermediate filament proteins, vimentin and nestin, and the cell cycle-associated protein, cyclin D1. Cellular tight junctions were lost in lased regions but re-expressed when cell replenishment was complete. In vivo, 2RT treatment gave rise to both an energy-dependent localised denudation of the RPE and the subsequent repopulation of lesion sites. Cell replenishment was associated with the increased expression of cyclin D1, vimentin and the heat shock proteins Hsp27 and αB-crystallin. CONCLUSIONS: The 2RT laser was able to target the RPE both in vitro and in vivo, causing debridement of the cells and the consequent stimulation of a wound-healing response leading to layer reformation.John P. M. Wood, Marzieh Tahmasebi, Robert J. Casson, Malcolm Plunkett, Glyn Chidlo

ANALISIS MAKNA PENGAMPUNAN DAN REKONSILIASI DALAM PERTEMANAN

Pengampunan dan rekonsiliasi menjadi dasar yang kuat untuk menciptakan ikatan yang kuat dan bertumbuh bersama dalam kedewasaan dalam menjalin pertemanan. Penting untuk memaknai pengampunan dan bertindak mengampuni sebelum seseorang melakukan rekonsiliasi dengan orang yang telah melakukan kesalahan dan melukainya, agar rekonsiliasi dilakukan menjadi penuh makna. Penelitian ini bertujuan untuk mengetahui pandangan biblis-psikologi mengenai pengampunan dan rekonsiliasi, makna pengampunan dan rekonsiliasi dalam pertemanan di antara mahasiswa di Sekolah Tinggi Teologi STT Satyabhakti di Malang, dan apakah terdapat kesesuaian di antara makna pengampunan dan rekonsiliasi dalam pertemanan mahasiswa STT Satyabhakti dengan pengampunan dan rekonsiliasi menurut pendangan biblis-psikologi. Penelitian ini menggunakan metode penelitian kualitatif dengan menggunakan pendekatan fenomenologi. 4 orang mahasiswa, yang terdiri dari mahasiswa Tingkat 1 hingga Tingkat 4, dipilih menjadi informan untuk mewakili setiap tingkat. Setiap informan pernah mengalami konflik dalam pertemanan dan dua dari keempat informan sedang berjuang hingga sekarang untuk dapat mengampuni dan melakukan rekonsiliasi. Teknik pengumpulan data yang digunakan dalam penelitian adalah wawancara mendalam, observasi dan dokumentasi. Data yang telah terkumpul dianalisis menggunakan model analisis dari Miles dan Huberman. Hasil dari penelitian menunjukkan bahwa semua informan memaknai pengampunan sebagai anugerah dan kasih yang mampu untuk melepaskan dendam atau kesalahan yang mungkin terjadi dalam hubungan pertemanan. Tiga dari empat informan melihat bahwa rekonsiliasi harus diawalidengan memaknai pengampunan agar rekonsiliasi menjadi bermakna, sementara satu dari keempat informan melihat bahwa rekonsiliasi terjadi terlebih dahulu. Namun, walaupun salah satu informan tersebut mengatakan rekonsiliasi terjadi lebih dahulu, tapi pada kenyataannya informan tersebut telah memaknai pengampunan terlebih dahulu sebelum melakukan rekonsiliasi. Dengan demikian rekonsiliasi harus diawali dengan memaknai pengampunan agar rekonsiliasi menjadi bermakna. Memaknai rekonsiliasi sebagai pemulihan dapat memperkuat hubungan, dan menolong untuk perkembangan dan kemampuan pertumbuhan pertemanan. Hasil penelitian menunjukkan bahwa tidak semua makna pengampunan dalam pertemanan mahasiswa STT Satyabhakti sesuai dengan pengampunan dan rekonsiliasi dalam pandangan biblis-psikologi, karena informan memiliki makna yang sama tentang pengampunan sebagai bukti kasih, anugerah, dan pembebasan dari dosa dan rasa bersalah. Namun, terdapat perbedaan pada makna pembebasan yang terjadi melalui pengampunan, yaitu pembebasan dari rasa sakit dan keinginan untuk balas dendam. Dalam memaknai rekonsiliasi, semua informan memaknainya sebagai pendamaian dan pemulihan hubungan. Disarankan agar mahasiswa tetap mempertahankan makna pengampunan dan rekonsialiasi dalam hubungan pertemanan mereka dapat mengalami pemulihan, penguatan dan pertumbuhan dalam kasih dan menjadi dewasa. Kata-kata Kunci: makna, pengampunan, rekonsiliasi, pertemana