A number of environmental stressors have been hypothesized as responsible for recent increases in limb malformations in several species of North American amphibians. The purpose of this study was to generate dose-response data suitable for assessing the potential role of solar ultraviolet (UV) radiation in causing limb malformations in a species in which this phenomenon seemingly is particularly prevalent, the northern leopard frog (Rana pipiens). Frogs were exposed from early embryonic stages through complete metamorphosis to varying natural sunlight regimes, including unaltered (100%) sunlight, sunlight subjected to neutral density filtration to achieve relative intensities of 85%, 75%, 65%, 50%, and 25% of unaltered sunlight, and sunlight filtered with glass or acrylamide to attenuate, respectively, the UVB (290-320 nm) and UVB plus UVA (290-380 nm) portions of the spectrum. The experiments were conducted in a controlled setting, with continual monitoring of UVB, UVA, and visible light to support a robust exposure assessment. Full sunlight caused approximately 50% mortality of the frogs during early larval development; no significant treatment-related mortality occurred under any of the other exposure regimes, including 100% sunlight with glass or acrylamide filtration. There was a dose-dependent (p < 0.0001) induction of hindlimb malformations in the frogs, with the percentage of affected animals ranging from about 97% under unaltered sunlight to 0% in the 25% neutral density treatment. Malformations were comprised mostly of missing or truncated digits, and generally were bilateral as well as symmetrical. Filtration of sunlight with either glass or acrylamide both significantly reduced the incidence of malformed limbs. The estimated sunlight dose resulting in a 50% limb malformation rate (ED50) was 63.5%. The limb ED50 values based on measured sunlight intensities corresponded to average daily doses of 4.5 and 100 Wh x m(-2) for UVB and UVA, respectively. Exposure to sunlight also resulted in increased eye malformations in R. pipiens, however, the dose-response relationship for this endpoint was not monotonic. The results of this study, in conjunction with measured or predicted exposure data from natural settings, provide a basis for quantitative prediction of the risk of solar UV radiation to amphibians.

Hypothalami from normal rats were examined after preparation with Gomori's chromalum-hematoxylin stain for neurosecretory material. In addition to the supraoptic and paraventricular nucleii, five additional nuclear masses of neurosecretory cells were found. These all formed more or less compact cellular groups, clearly demarcated from surrounding neural tissue and with constant location from animal to animal. One nucleus, immediately posterior to the anterior commissure, along the ventricular wall, is termed anterior commissural. Two others, being dorso-lateral to the columns of the fornix, are termed anterior and posterior fornical. Midway between the paraventricular nucleus and the optic tract, a characteristically shaped nucleus of very compact cells, the nucleus circularis, is encountered. Finally, another group of cells is seen dorsal to the optic tract in the middle of the medial forebrain bundle, the nucleus of the medial forebrain bundle.

Highlights d Elav regulates Dscam1 long 3 0 UTR (Dscam1-L) biogenesis d Long-read sequencing reveals connectivity of long 3 0 UTR to skipping of upstream exon 19 d Loss of Dscam1-L impairs axon outgrowth d Dscam1 long 3 0 UTR is required for correct splicing of exon 19

BackgroundMesenchymal stromal cells (MSCs) can be used intra-articularly to quell inflammation and promote cartilage healing; however, mechanisms by which MSCs mitigate joint disease remain poorly understood. Galectins, a family of β-galactoside binding proteins, regulate inflammation, adhesion and cell migration in diverse cell types. Galectin-1 and galectin-3 are proposed to be important intra-articular modulators of inflammation in both osteoarthritis and rheumatoid arthritis. Here, we asked whether equine bone marrow-derived MSCs (BMSCs) express higher levels of galectin-1 and -3 relative to synovial fibroblasts and chondrocytes and if an inflammatory environment affects BMSC galectin expression and motility.MethodsEquine galectin-1 and -3 gene expression was quantified using qRT-PCR in cultured BMSCs, synoviocytes and articular chondrocytes, in addition to synovial membrane and articular cartilage tissues. Galectin gene expression, protein expression, and protein secretion were measured in equine BMSCs following exposure to inflammatory cytokines (IL-1β 5 and 10 ng/mL, TNF-α 25 and 50 ng/mL, or LPS 0.1, 1, 10 and 50 μg/mL). BMSC focal adhesion formation was assessed using confocal microscopy, and BMSC motility was quantified in the presence of inflammatory cytokines (IL-1β or TNF-α) and the pan-galectin inhibitor β-lactose (100 and 200 mM).ResultsEquine BMSCs expressed 3-fold higher galectin-1 mRNA levels as compared to cultured synovial fibroblasts (p = 0.0005) and 30-fold higher galectin-1 (p < 0.0001) relative to cultured chondrocytes. BMSC galectin-1 mRNA expression was significantly increased as compared to carpal synovial membrane and articular cartilage tissues (p < 0.0001). IL-1β and TNF-α treatments decreased BMSC galectin gene expression and impaired BMSC motility in dose-dependent fashion but did not alter galectin protein expression. β-lactose abrogated BMSC focal adhesion formation and inhibited BMSC motility.ConclusionsEquine BMSCs constitutively express high levels of galectin-1 mRNA relative to other articular cell types, suggesting a possible mechanism for their intra-articular immunomodulatory properties. BMSC galectin expression and motility are impaired in an inflammatory environment, which may limit tissue repair properties following intra-articular administration. β-lactose-mediated galectin inhibition also impaired BMSC adhesion and motility. Further investigation into the effects of joint inflammation on BMSC function and the potential therapeutic effects of BMSC galectin expression in OA is warranted.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-017-0691-2) contains supplementary material, which is available to authorized users.

Long-read sequencing reveals exon connectivity to long 3′ UTR Loss of Dscam1-L impairs axon outgrowth Elav-mediated regulation of Dscam1 alternative splicing and APA Long 3′ UTR influences exon 19 alterantive splicing EARLY RNA-Seq Graphical Abstract LATE Embryos Dscam1-S Dscam1-L + Elav Elav ? Highlights: -Elav regulates Dscam1 long 3′ UTR (Dscam1-L) biogenesis -Long-read sequencing reveals connectivity of long 3′ UTR to skipping of upstream exon 19 -Loss of Dscam1-L impairs axon outgrowth -Dscam1 long 3′ UTR is required for correct splicing of exon 19 Elav-mediated exon skipping and alternative polyadenylation of the Dscam1 gene is required for axon outgrowth Summary: Many metazoan genes express alternative long 3′ UTR isoforms in the nervous system, but their functions remain largely unclear. In Drosophila melanogaster, the Dscam1 gene generates short and long (Dscam1-L) 3′ UTR isoforms due to alternative polyadenylation (APA). Here, we found that the RNA-binding protein Embryonic Lethal Abnormal Visual System (Elav) impacts Dscam1 biogenesis at two levels, including regulation of long 3´ UTR biogenesis and skipping of an upstream exon (exon 19). MinION long-read sequencing confirmed the connectivity of this alternative splicing event to the long 3′ UTR. Knockdown or CRISPR deletion of Dscam1-L impaired axon growth in Drosophila. The Dscam1 long 3´ UTR was found to be required for correct Elav-mediated skipping of exon 19. Elav thus co-regulates APA and alternative splicing to generate specific Dscam1 transcripts that are essential for neural development. This coupling of APA to alternative splicing might represent a new class of regulated RNA processing.

—In vitro experiments were performed in order to determine whether nerve stimulation would affect the RNA metabolism of an identified giant neurone (R2) in the abdominal ganglion of Aplysia californica. The electrophysiological activity of the neurone was continuously monitored with an intra‐ or extracellular microelectrode. The mere presence of an intracellular microelectrode inside the neurone had no significant effect on the incorporation of tritiated nucleosides into the RNA of the giant neurone. Prolonged electrical stimulation of ganglionic nerves, strong enough to elicit post‐synaptic spikes in the giant neurone, produced a marked increase in the amount of labelled RNA in the nucleus as well as in the cytoplasm. Electrophoresis studies suggested that this increase in labelling might concern RNA with molecular weights corresponding to ribosomal as well as to non‐ribosomal RNA.

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