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1.
Life Sci Alliance ; 7(7)2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38719748

RESUMO

Rab6 is a key modulator of protein secretion. The dynein adapter Bicaudal D2 (BicD2) recruits the motors cytoplasmic dynein and kinesin-1 to Rab6GTP-positive vesicles for transport; however, it is unknown how BicD2 recognizes Rab6. Here, we establish a structural model for recognition of Rab6GTP by BicD2, using structure prediction and mutagenesis. The binding site of BicD2 spans two regions of Rab6 that undergo structural changes upon the transition from the GDP- to GTP-bound state, and several hydrophobic interface residues are rearranged, explaining the increased affinity of the active GTP-bound state. Mutations of Rab6GTP that abolish binding to BicD2 also result in reduced co-migration of Rab6GTP/BicD2 in cells, validating our model. These mutations also severely diminished the motility of Rab6-positive vesicles in cells, highlighting the importance of the Rab6GTP/BicD2 interaction for overall motility of the multi-motor complex that contains both kinesin-1 and dynein. Our results provide insights into trafficking of secretory and Golgi-derived vesicles and will help devise therapies for diseases caused by BicD2 mutations, which selectively affect the affinity to Rab6 and other cargoes.


Assuntos
Dineínas , Ligação Proteica , Proteínas rab de Ligação ao GTP , Proteínas rab de Ligação ao GTP/metabolismo , Proteínas rab de Ligação ao GTP/genética , Humanos , Dineínas/metabolismo , Dineínas/química , Sítios de Ligação , Cinesinas/metabolismo , Cinesinas/química , Cinesinas/genética , Mutação , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Associadas aos Microtúbulos/química , Transporte Proteico , Modelos Moleculares , Guanosina Trifosfato/metabolismo
2.
Arch Environ Contam Toxicol ; 75(1): 75-86, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29725722

RESUMO

Penguins are reliable sentinels for environmental assessments of mercury (Hg) due to their longevity, abundance, high trophic level, and relatively small foraging areas. We analyzed Hg concentrations from blood and feathers of adult Humboldt penguins (Spheniscus humboldti) and feathers of chinstrap penguins (Pygoscelis antarcticus) from different reproductive colonies with variable degrees of urbanization and industrialization along the Chilean and Antarctic coasts. We evaluated Hg concentration differences between species, sexes (Humboldt penguins), and localities. Our results showed significantly greater levels in Humboldt penguins than in chinstrap penguins and nonsignificant differences between sexes among Humboldts. Penguin Hg concentrations showed a latitudinal pattern, with greater values of the metal at lower latitudes, independent of the species. Both studied penguin species showed elevated Hg concentrations compared to their congeners, highlighting the necessity to investigate potential negative effects on their populations. Although differences between species are possibly due to variation in diet and trophic level, our results suggest an important effect of the degree of Hg pollution adjacent to foraging areas. Further research on Hg content in prey species and environmental samples, together with a larger overall sample size, and investigation on penguin's diet and trophic level are needed to elucidate Hg bioavailability in each location and the role of local Hg pollution levels. Likewise, it is important to monitor Hg and other heavy metals of ecotoxicological importance in penguin populations in vulnerable regions of Chile.


Assuntos
Exposição Ambiental/análise , Mercúrio/análise , Spheniscidae , Animais , Regiões Antárticas , Chile , Ecotoxicologia/métodos , Monitoramento Ambiental/métodos , Plumas/química , Feminino , Masculino , Mercúrio/sangue , Fatores Sexuais
3.
Plant Signal Behav ; 10(2): e976487, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25826257

RESUMO

The electrical response of plants to environmental stimuli can be measured and quantitatively related to the intensity of several stimulating sources, like temperature, solar radiation, soil water content, evapotranspiration rates, sap flow and dendrometric cycles. These relations can be used to assess the influence of different environmental situations on soil water availability to plants, defined as a steady state condition between leaf transpirative flow and soil water flow to plant roots. A restricted soil water flow due to soil dryness can trigger water stress in plants, if the atmospheric evaporative demand is high, causing partial stomata closure as a physiological response to avoid plant dehydration; water stressed and unstressed plants manifest a differential electrical response. Real time plant electrical response measurements can anticipate actions that prevent the plant reaching actual stress conditions, optimizing stomata gas exchange and photosynthetic rates. An electrophysiological sensor developed in this work, allows remote real-time recording information on plant electrical potential (EP) in the field, which is highly related to EP measurements obtained with a laboratory Keithley voltmeter sensor used in an highly controlled experimental setup. Our electrophysiological sensor is a wireless, autonomous devise, which transmits EP information via Internet to a data server. Using both types of sensors (EP electrodes with a Keithley voltmeter and the electrophysiological sensor), we measured in real time the electrical responses of Persea americana and Prunus domestica plants, to induced water deficits. The differential response for 2 scenarios: irrigation and water restriction is identified by a progressive change in slope on the daily maximal and minimal electric signal values in stressed plants, and a zero-slope for similar signals for well-watered plants. Results show a correspondence between measured signals obtained by our electrophysiological sensor and the EP electrodes connected to the Keithley voltmeter in each irrigation stage. Also, both sensors show a daily cyclical signal (circadian cycle).


Assuntos
Irrigação Agrícola , Fenômenos Eletrofisiológicos , Persea/fisiologia , Prunus/fisiologia , Madeira/fisiologia , Eletrofisiologia/instrumentação
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