An interactome-centered protein discovery approach reveals novel components involved in mitosome function and homeostasis in giardia lamblia

Protozoan parasites of the genus Giardia are highly prevalent globally, and infect a wide range of vertebrate hosts including humans, with proliferation and pathology restricted to the small intestine. This narrow ecological specialization entailed extensive structural and functional adaptations during host-parasite co-evolution. An example is the streamlined mitosomal proteome with iron-sulphur protein maturation as the only biochemical pathway clearly associated with this organelle. Here, we applied techniques in microscopy and protein biochemistry to investigate the mitosomal membrane proteome in association to mitosome homeostasis. Live cell imaging revealed a highly immobilized array of 30–40 physically distinct mitosome organelles in trophozoites. We provide direct evidence for the single giardial dynamin-related protein as a contributor to mitosomal morphogenesis and homeostasis. To overcome inherent limitations that have hitherto severely hampered the characterization of these unique organelles we applied a novel interaction-based proteome discovery strategy using forward and reverse protein co-immunoprecipitation. This allowed generation of organelle proteome data strictly in a protein-protein interaction context. We built an initial Tom40-centered outer membrane interactome by co-immunoprecipitation experiments, identifying small GTPases, factors with dual mitosome and endoplasmic reticulum (ER) distribution, as well as novel matrix proteins. Through iterative expansion of this protein-protein interaction network, we were able to i) significantly extend this interaction-based mitosomal proteome to include other membrane-associated proteins with possible roles in mitosome morphogenesis and connection to other subcellular compartments, and ii) identify novel matrix proteins which may shed light on mitosome-associated metabolic functions other than Fe-S cluster biogenesis. Functional analysis also revealed conceptual conservation of protein translocation despite the massive divergence and reduction of protein import machinery in Giardia mitosomes

Degradation behaviors and mechanisms of MoS2 crystals relevant to bioabsorbable electronics

Monolayer molybdenum disulfide (MoS2) exhibits unique semiconducting and bioresorption properties, giving this material enormous potential for electronic/biomedical applications, such as bioabsorbable electronics. In this regard, understanding the degradation performance of monolayer MoS2 in biofluids allows modulation of the properties and lifetime of related bioabsorbable devices and systems. Herein, the degradation behaviors and mechanisms of monolayer MoS2 crystals with different misorientation angles are explored. High-angle grain boundaries (HAGBs) biodegrade faster than low-angle grain boundaries (LAGBs), exhibiting degraded edges with wedge and zigzag shapes, respectively. Triangular pits that formed in the degraded grains have orientations opposite to those of the parent crystals, and these pits grow into larger pits laterally. These behaviors indicate that the degradation is induced and propagated based on intrinsic defects, such as grain boundaries and point defects, because of their high chemical reactivity due to lattice breakage and the formation of dangling bonds. High densities of dislocations and point defects lead to high chemical reactivity and faster degradation. The structural cause of MoS2 degradation is studied, and a feasible approach to study changes in the properties and lifetime of MoS2 by controlling the defect type and density is presented. The results can thus be used to promote the widespread use of two-dimensional materials in bioabsorption applications

Quality of beechnuts from different crop years

Fresh and stored beechnuts collected in 1992, 1995, 1998, 1999 and 2000 were tested for viability and in 1998, 1999 and 2000 also for germination. Germination parameters such as peakvalue, mean weekly germination (modified mean daily germination), germination capacity, and germination value (Czabator 1962) were calculated from the germination test data and these indicators were also used for comparing beechnut quality. The highest viability for pre-stored beechnuts occurred in 1998 (80%) and this increased by 4% when these seedlots were stored for 1.5 years. Viability of fresh beechnuts collected in 1992, 1995 and 1999 was 64, 73 and 77%, respectively. Viability of 1995-collected beechnuts decreased after 3 years storage. Germination of fresh seeds was only done for the 1998, 1999 and 2000 collections where the best germination occurred for the 1998 collection. Germination of beechnuts collected in 1992 and 1995 was significantly reduced after 3 and 6 years of storage, respectively, while beechnuts collected in 1998 and stored for 1.5 years germinated about 15% better than fresh seeds of the 1999 crop. The peakvalue, mean weekly germination and the time required for viable seeds to reach 80% germination showed that the 1998 crop had the highest, overall quality. Eighty percent of the viable seeds collected in 1998 germinated in 9-10 weeks while fresh beechnuts from 1999 needed nearly 13 weeks to germinate, as did beechnuts collected in 1992 and stored for 7 years. Besides the germination capacity the germination value seems to be the very good indicator for determining the quality of stored beechnuts