How do the sizes of intracellular organelles adapt to reductions in cell size that occur during early embryogenesis? We address mechanisms of developmental organelle size scaling in a variety of model organisms and, if known, the functional significance of scaling.

Nuclear shape influences cell migration, gene expression, and cell cycle progression, while being altered in disease states like laminopathies and cancer. What factors and forces determine nuclear shape? We find that nuclei assembled in Xenopus egg extracts in the presence of dynamic F-actin exhibit a striking bilobed nuclear morphology with distinct membrane compositions in the two lobes and accumulation of F-actin at the inner nuclear envelope. Absent from Xenopus eggs, Lamin A addition results in rounder nuclei, suggesting that opposing nuclear F-actin and Lamin A forces contribute to the regulation of nuclear shape. Nuclear F-actin also promotes altered nuclear shape in Lamin A knockdown HeLa cells, and, in both systems, abnormal nuclear shape is driven by formins and not Arp2/3 or myosin. Although the underlying mechanisms may differ in Xenopus and HeLa cells, we propose that nuclear F-actin filaments nucleated by formins impart outward forces that lead to altered nuclear morphology unless Lamin A is present. Targeting nuclear actin dynamics may represent a novel approach to rescuing disease-associated defects in nuclear shape.

While changes in nuclear structure and organization are frequently observed in cancer cells, relatively little is known about how nuclear architecture impacts cancer progression and pathology. To begin to address this question, we studied Nuclear Transport Factor 2 (NTF2) because its levels decrease during melanoma progression. We show that increasing NTF2 expression in WM983B metastatic melanoma cells reduces cell proliferation and motility while increasing apoptosis. We also demonstrate that increasing NTF2 expression in these cells significantly inhibits metastasis and prolongs survival of mice. NTF2 levels affect the expression and nuclear positioning of a number of genes associated with cell proliferation and migration, and increasing NTF2 expression leads to changes in nuclear size, nuclear lamin A levels, and chromatin organization. Thus, ectopic expression of NTF2 in WM983B metastatic melanoma abrogates phenotypes associated with advanced stage cancer both in vitro and in vivo, concomitantly altering nuclear and chromatin structure and generating a gene expression profile with characteristics of primary melanoma. We propose that NTF2 is a melanoma tumor suppressor and could be a novel therapeutic target to improve health outcomes of melanoma patients.

Minimization of deleterious effects of chemical fertilizers on health, ecosystem and economy can only be achieved by finding healthy, ecofriendly and cheap alternatives. Naturally selected symbiotic relationship between the endophytic bacteria and their host plants makes them an ideal candidate as biofertilizer. They can synthesize various plant growth hormones as well as assist their host in uptake of nutrients from soil.The study was designed to compare plant growth promotion of Solanum lycopersicum by Bacillus spp., Pseudomonas spp. and total endophytic community isolated from roots of S. lycopersicum, grown in the soil samples collected from various locations of Kathmandu valley of Nepal. Tomato seeds were inoculated with mixtures of eight endophytic strains of Bacillus spp. and Pseudomonas spp., and crude endophytes obtained from each location separately.Endophytic treatments, except Pseudomonas spp., inhibited seminal root growth during 12-days germination period. However, after plantation, root and shoot biomass was enhanced by the endophytes, with no significant differences among the bacterial treatments. The shoot height was also enhanced, among which Pseudomonas spp. had the strongest effect. In phosphate solubilization assay, out of seventy-two isolates each of Bacillus spp. and Pseudomonas spp. tested, twenty-four isolates of Pseudomonas spp. and sixteen isolates of Bacillus spp. could solubilize phosphate. Higher number of phosphate solubilizing isolates of Pseudomonas spp. might provide a possible explanation for the greater enhancement of shoot height by Pseudomonas spp. as compared to Bacillus spp.

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