Interaction of microtubules and actin during the post-fusion phase of exocytosis

Exocytosis is the intracellular trafficking step where a secretory vesicle fuses with the plasma membrane to release vesicle content. Actin and microtubules both play a role in exocytosis; however, their interplay is not understood. Here we study the interaction of actin and microtubules during exocytosis in lung alveolar type II (ATII) cells that secrete surfactant from large secretory vesicles. Surfactant extrusion is facilitated by an actin coat that forms on the vesicle shortly after fusion pore opening. Actin coat compression allows hydrophobic surfactant to be released from the vesicle. We show that microtubules are localized close to actin coats and stay close to the coats during their compression. Inhibition of microtubule polymerization by colchicine and nocodazole affected the kinetics of actin coat formation and the extent of actin polymerisation on fused vesicles. In addition, microtubule and actin cross-linking protein IQGAP1 localized to fused secretory vesicles and IQGAP1 silencing influenced actin polymerisation after vesicle fusion. This study demonstrates that microtubules can influence actin coat formation and actin polymerization on secretory vesicles during exocytosis

Use of pentoxifylline during ovarian stimulation to improve oocyte and embryo quality: A retrospective study

Objective: This study aims to investigate if the administration of pentoxifylline during ovarian stimulation have an impact on the quantity and quality of oocytes recovered for in vitro fertilization (IVF), the quality of zygotes and embryos resulting from IVF, the serum estradiol and progesterone concentrations, the endometrial thickness and pregnancy outcomes after embryo transfer. Methods: Retrospective crossover study including 18 women with recurrent implantation failur, defined as having a history of at least two consecutive cycles of implantation failure and 25-45 years of age at the time of embryo transfer. Pentoxifylline was added during their following IVF attempt aiming to improve endometrial function. Oocyte, zygote and embryo quality, serum estradiol and progesterone concentrations, endometrial thickness and IVF outcomes were compared between the two sequential attempts. Results: Compared to the first attempt, the outcomes of the second attempt, with the addition of pentoxifylline administration, resulted in higher numbers of total and mature oocytes, better oocyte, zygote and embryo quality, higher serum estradiol concentrations, thicker endometrium and better clinical IVF outcomes. Conclusions: The administration of pentoxifylline during ovarian stimulation seems to improve IVF outcomes, not only by the generating a thicker endometrial lining, but also by producing a higher number of oocytes, with better oocyte, zygote and embryo quality, and higher serum estradiol concentrations

Global Island Monitoring Scheme (GIMS): a proposal for the long-term coordinated survey and monitoring of native island forest biota

Islands harbour evolutionary and ecologically unique biota, which are currently disproportionately threatened by a multitude of anthropogenic factors, including habitat loss, invasive species and climate change. Native forests on oceanic islands are important refugia for endemic species, many of which are rare and highly threatened. Long-term monitoring schemes for those biota and ecosystems are urgently needed: (i) to provide quantitative baselines for detecting changes within island ecosystems, (ii) to evaluate the effectiveness of conservation and management actions, and (iii) to identify general ecological patterns and processes using multiple island systems as repeated ‘natural experiments’. In this contribution, we call for a Global Island Monitoring Scheme (GIMS) for monitoring the remaining native island forests, using bryophytes, vascular plants, selected groups of arthropods and vertebrates as model taxa. As a basis for the GIMS, we also present new, optimized monitoring protocols for bryophytes and arthropods that were developed based on former standardized inventory protocols. Effective inventorying and monitoring of native island forests will require: (i) permanent plots covering diverse ecological gradients (e.g. elevation, age of terrain, anthropogenic disturbance); (ii) a multiple-taxa approach that is based on standardized and replicable protocols; (iii) a common set of indicator taxa and community properties that are indicative of native island forests’ welfare, building on, and harmonized with existing sampling and monitoring efforts; (iv) capacity building and training of local researchers, collaboration and continuous dialogue with local stakeholders; and (v) long-term commitment by funding agencies to maintain a global network of native island forest monitoring plots