Expression and Trafficking of the γ Subunit of Na,K-ATPase in Hypertonically Challenged IMCD3 Cells

The γ subunit (FXYD2) of Na,K-ATPase is an important regulator of the sodium pump. In this investigation we have analysed the trafficking of γ to the plasma membrane in cultures of inner medullary collecting duct cells (IMCD3) following acute hypertonic challenge and brefeldin A (BFA) treatment. Following hypertonic challenging for 24 hr immunofluorescence labeling revealed initial co-localization of the γ subunit and 58K Golgi protein in the cytoplasm, but no co-localization of α1 and Golgi protein. Exposure of the challenged cells to BFA prevented the subsequent incorporation of γ into the basolateral plasma membrane. The γ subunit instead remained in cytoplasmic vesicles while cell proliferation and cell viability decreased simultaneously. Following removal of BFA from the hypertonic medium the IMCD3 cells recovered with distinct expression of γ in the basolateral membrane. The α1 subunit was only marginally influenced by BFA. The results demonstrate that the γ subunit trafficks to the plasma membrane via the Golgi apparatus, despite the absence of a signal sequence. The results also suggest that the γ and α subunits do not traffic together to the plasma membrane, and that the γ and α subunit have different turnover rates during these experimental conditions

Effects of a dicamba/MCPA/mecoprop herbicide mixture on the leaves of a barley variety

Plants of a barley cultivar Pomo were sprayed at 2-node stage with a herbicide mixture, ’Mepro Special’, containing dicamba, MCPA and mecoprop, and the plants were grown at two different temperatures. 15°C and 23° C. The effects of the herbicide on the morphology and anatomy were studied by light and electron microscopes and the effects on the chlorophyll content of leaves were studied at various intervals after the spraying. First sign of damage in the morphology of plants grown both at 23° C and 15°C were observable 10-12 days after the spraying but those in the ultrastructure as soon as 1 day after the treatment. The cells of the vascular bundle sheath were most sensitive while the mesophyll cells were unchanged during the total observation period of 12 days at 15°C. At a higher temperature injuries of various stages were observable also in the mesophyll 6 days after the treatment. The clearest alterations became visible in the chloroplasts. They swelled to spherical in shape, the intergrana and later also grana lamellae formed vesicles by dilating, later they broke down, and ultimately the plastid envelope disintegrated. The amount of starch and chlorophyll decreased, whereas the number and size of osmiophilic plastoglobuli increased significantly. The mitochondria swelled, the cristae frequently disappeared and the outer membrane of the envelope distended largely. The nucleus was best capable of resisting the toxic effects of the herbicide. The tonoplast and plasmalemma were broken down a short time before the final disintegration of the cell structures. High temperature obviously reinforced the toxic effects of the herbicide mixture

Dikamba/MCPA/mekoproppi-herbisidiseoksen vaikutukset ohran lehteen

Plants of a barley cultivar Pomo were sprayed at 2-node stage with a herbicide mixture, ’Mepro Special’, containing dicamba, MCPA and mecoprop, and the plants were grown at two different temperatures. 15°C and 23° C. The effects of the herbicide on the morphology and anatomy were studied by light and electron microscopes and the effects on the chlorophyll content of leaves were studied at various intervals after the spraying. First sign of damage in the morphology of plants grown both at 23° C and 15°C were observable 10-12 days after the spraying but those in the ultrastructure as soon as 1 day after the treatment. The cells of the vascular bundle sheath were most sensitive while the mesophyll cells were unchanged during the total observation period of 12 days at 15°C. At a higher temperature injuries of various stages were observable also in the mesophyll 6 days after the treatment. The clearest alterations became visible in the chloroplasts. They swelled to spherical in shape, the intergrana and later also grana lamellae formed vesicles by dilating, later they broke down, and ultimately the plastid envelope disintegrated. The amount of starch and chlorophyll decreased, whereas the number and size of osmiophilic plastoglobuli increased significantly. The mitochondria swelled, the cristae frequently disappeared and the outer membrane of the envelope distended largely. The nucleus was best capable of resisting the toxic effects of the herbicide. The tonoplast and plasmalemma were broken down a short time before the final disintegration of the cell structures. High temperature obviously reinforced the toxic effects of the herbicide mixture.Ohran Pomo-lajikkeen 2-solmuasteella olevia yksilöitä ruiskutettiin kotimaisella 'Mepro Special'-rikkakasvihävitteellä, joka sisältää dikambaa, MCPA:ta ja mekoproppia. Käsiteltyjä ja kontrollikasveja kasvatettiin tämän jälkeen 15°C tai 23° C:ssa pitkän päivän olosuhteissa pimeäjakson lämpötilan ollessa 10°C. Lehdistä otettiin näytteitä valo- ja elektronimikroskopiaa varten sekä klorofyllimäärityksiin eri aikoina 12 päivän kuluessa. Kasvien morfologiassa nähtiin ensimmäiset merkit herbisidin haittavaikutuksista lehtien kellastumisena molemmissa lämpötiloissa vasta 10—12 päivää ruiskuttamisen jälkeen. Hienorakenteessa sensijaan näkyi muutoksia johtojännetupensoluissa selvästi jo 1 päivän kuluttua. Mesofyllin solut pysyivät lähes muuttumattomina 15°C:ssa koko havaintojentekoajan, mutta 23° C:ssa vaurioita alkoi esiintyä selvästi 6 päivän kuluttua. Organelleista herkimpiä olivat kloroplastit, joiden muoto aluksi muuttui pyöreäksi. Ensin paisuivat intergranatylakoidit ja sitten granatylakoidit muodostaen pieniä rakkuloita. Osmiofiilisten plastoglobuloitten määrä ja koko kasvoi huomattavasti. Myöhempiä vaurioitumisen merkkejä olivat lamellien ja kloroplastikelmun sekä tonoplastin rikkoontuminen. Myös mitokondriot turposivat, ja kristat saattoivat hävitä kokonaan. Usein kelmun ulompikalvo irtosi sisäkalvosta venyen pussimaisesti. Plasmalemman rikkoonnuttua solun kaikki rakenteet hajosivat. Tärkkelyksen määrässä todettiin huomattava nousu 15°C:ssa kasvaneissa kasveissa 3 t käsittelyn jälkeen, mutta 1 pv käsittelystä sekä tärkkelyksen että klorofyllin määrä alkoivat laskea. Korkea lämpötila lisäsi selvästi myrkkyvaikutuksia, mikä näkyi rakenteiden muutoksinakin. Riittävästä kastelusta huolimatta voitiin todeta, että 6 pv 23° C:ssa kasvaneissa kontrollikasveissa alkoi esiintyä yleisiä solun vanhenemiseen liittyviä muutoksia, osoittaen Pomo-lajikkeen kärsivän aineenvaihdunnan eri tasoilla

Effects of a dicamba/MCPA/mecoprop herbicide mixture on the leaves of a barley variety

vokKirjasto Aj-KDikamba/MCPA/mekoproppi-herbisidiseoksen vaikutukset Ohran lehtee

Cold acclimation of subarctic Diapensia lapponica L.

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Snow-Mold-Induced Apoplastic Proteins in Winter Rye Leaves Lack Antifreeze Activity

During cold acclimation, winter rye (Secale cereale L.) plants secrete antifreeze proteins that are similar to pathogenesis-related (PR) proteins. In this experiment, the secretion of PR proteins was induced at warm temperatures by infection with pink snow mold (Microdochium nivale), a pathogen of overwintering cereals. A comparison of cold-induced and pathogen-induced proteins showed that PR proteins accumulated in the leaf apoplast to a greater level in response to cold. The PR proteins induced by cold and by snow mold were similar when separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and examined by immunoblotting. Both groups of PR proteins contained glucanase-like, chitinase-like, and thaumatin-like proteins, and both groups exhibited similar levels of glucanase and chitinase activities. However, only the PR proteins induced by cold exhibited antifreeze activity. Our findings suggest that the cold-induced PR proteins may be isoforms that function as antifreeze proteins to modify the growth of ice during freezing while also providing resistance to the growth of low-temperature pathogens in advance of infection. Both functions of the cold-induced PR proteins may improve the survival of overwintering cereals