The diverse morphology of vertebrate skeletal system is genetically controlled, yet the means by which cells shape the skeleton remains to be fully illuminated. Here we perform quantitative analyses of cell behaviours in the growth plate cartilage, the template for long bone formation, to gain insights into this process. Using a robust avian embryonic organ culture, we employ time-lapse two-photon laser scanning microscopy to observe proliferative cells' behaviours during cartilage growth, resulting in cellular trajectories with a spreading displacement mainly along the tissue elongation axis. We build a novel software toolkit of quantitative methods to segregate the contributions of various cellular processes to the cellular trajectories. We find that convergent-extension, mitotic cell division, and daughter cell rearrangement do not contribute significantly to the observed growth process; instead, extracellular matrix deposition and cell volume enlargement are the key contributors to embryonic cartilage elongation.

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Dynamic imaging of the growth plate cartilage reveals multiple contributors to skeletal morphogenesis.

The diverse morphology of vertebrate skeletal system is genetically controlled, yet the means by which cells shape the skeleton remains to be fully illuminated. Here, we perform a quantitative anal...

Dynamic imaging of the growth plate cartilage reveals multiple contributors to skeletal morphogenesis

The aim of this study was to evaluate the capacity of domestic cat (Dc, Felis silvestris) oocytes to reprogram the nucleus of cheetah (Ch, Acinonyx jubatus) cells by interspecies SCNT (iSCNT), by using embryo aggregation Dc oocytes were in vitro matured and subjected to zona pellucida free (ZP-free) SCNT or iSCNT, depending on whether the nucleus donor cell was of Dc or Ch respectively ZP-free reconstructed embryos were then cultured in microwells individually (Dc1X and Ch1X groups) or in couples (Dc2X and Ch2X groups) Embryo aggregation improved in vitro development obtaining 274, 477, 167 and 283% of blastocyst rates in the Dc1X, Dc2X, Ch1X and Ch2X groups, respectively (P<005) Moreover, aggregation improved the morphological quality of blastocysts from the Dc2X over the Dc1X group Gene expression analysis revealed that Ch1X and Ch2X blastocysts had significantly lower relative expression of OCT4, CDX2 and NANOG than the Dc1X, Dc2X and IVF control groups The OCT4, NANOG, SOX2 and CDX2 genes were overexpressed in Dc1X blastocysts, but the relative expression of these four genes decreased in the Dc2X, reaching similar relative levels to those of Dc IVF blastocysts In conclusion, Ch blastocysts were produced using Dc oocytes, but with lower relative expression of pluripotent and trophoblastic genes, indicating that nuclear reprogramming could be still incomplete Despite this, embryo aggregation improved the development of Ch and Dc embryos, and normalized Dc gene expression, which suggests that this strategy could improve full-term developmental efficiency of cat and feline iSCNT embryos

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Cheetah interspecific SCNT followed by embryo aggregation improves in vitro development but not pluripotent gene expression.

Two-photon fluorescence scanning confocal microscopy sensitive to circular dichroism with a diffraction-limited resolution well below 500 nm is demonstrated. With this method, the spatial variation of the circular dichroism of thermally annealed chiral polyfluorene thin films has been imaged. We observed circular dichroism associated with submicrometer-sized domains showing helicoidally twisted macromolecular organization. Domains with opposite chiroptical properties, corresponding to left- or right-handed molecular organization, coexist in the film. Our results are consistent with those obtained by one-photon imaging and illustrate the potential of two-photon imaging for use in studying helical macromolecular organization.

Circular Dichroism Probed by Two-Photon Fluorescence Microscopy in Enantiopure Chiral Polyfluorene Thin Films

A stochastic model was developed to explore policy scenarios designed to address the long-term sustainability of the farming sector in Western Uzbekistan. The model results evidence the need to move away from high input cropping systems, towards alternative crops. Reduced water use was obtained with the introduction of water-wise technologies, such as laser leveling and drip irrigation. In light of natural and man made water shortages in the region, a more sustainable farming system requires greater collective investment among Water User Associations (WUAs) as well as the redirection of government subsidies toward more environmentally friendly farming methods.

Henry S. Williams

Papers

On the theory of organic variation.

Pal.eontological researches.

The photography of fossils.