Root Hair Deformations Associated with Fractionated Extracts from Rhizobium trifolii

Components from culture fluid and whole cells of Rhizobium trifolii were examined for effects on root hair morphology of white clover seedlings (Trifolium repens var. Ladino). Cell-free culture fluid, exopolysaccharides, supernatant fluid from the precipitation of the exopolysaccharides, capsular polysaccharides, lipopolysaccharides, and a protein fraction from culture fluids were assayed for morphogenetic effects on the root hairs of axenically grown clover seedlings. Crude fractions were chromatographed on Bio Gel A-5m (Bio-Rad Laboratories), and fractions collected were similarly assayed. Hexose, uronic acid, and protein concentrations were determined for all fractions assayed. Gel chromatography indicated the materials with deforming ability to be of high molecular weight (>10,000). For all fractions except exopolysaccharide, deforming ability was associated with a protein component. This suggested that two components were associated with deformation; both contained polysaccharides and one contained protein. Crude fractions differed in their ability to cause deformations and indicated the following relative ability (in decreasing order) to deform root hairs: cell-free culture fluid, capsular polysaccharides, protein from culture fluids, exopolysaccharide, and cell envelope. Lipopolysaccharides had no effect.     

Evidence for an Astrocyte-Derived Vasorelaxing Factor with Properties Similar to Nitric Oxide

To determine whether astrocytes release nonprostanoid vasodilators, cells on microcarrier beads were superfused with various agents in the presence of indomethacin, and the effluent was bioassayed and also analyzed for nitric oxide by a chemiluminescence technique. Bradykinin and A23187 induced release of a factor that relaxed arterial rings, an effect that was blocked by hemoglobin. The effluent contained either nitric oxide or a related compound that could be reduced to nitric oxide. Production of this factor was competitively inhibited by the arginine analogs NG-nitro-L-arginine and NG-methyl-L-arginine and could be restored with L-arginine. Quisqualate and norepinephrine were also effective in causing the release of nitric oxide from astroglial cells. Thus, astrocyte-derived relaxing factor has properties similar to those of an endothelium- and neuron-derived relaxing factor.     

Limbal niche cells are a potent resource of adult mesenchymal progenitors

Limbal niche cells located in the limbal Palisades of Vogt are mesenchymal stem cells that reside next to limbal basal epithelial cells. Limbal niche cells are progenitors that express embryonic stem cell markers such as Nanog, Nestin, Oct4, Rex1, Sox2 and SSEA4, mesenchymal cell markers such as CD73, CD90 and CD105, and angiogenesis markers such as Flk‐1, CD31, CD34, VWF, PDGFRβ and α‐SMA, but negative for CD45. In addition, the stemness of limbal niche cells can be maintained during their cell culture in a three‐dimension environment. Furthermore, expanded limbal niche cells have the capability to undergo adipogenesis, chondrogenesis, osteogenesis and endogenesis in vitro, indicating that they are in fact a valuable resource of adult progenitors. Furthermore studies on how the limbal niche cells regulate the aforementioned stemness and corneal fate decision are warranted, as those investigations will shed new light on how mesenchymal progenitors reverse limbal stem cell deficiency and lead to new methods for limbal niche cell treatment.     

The Yeast INO80 Complex Operates as a Tunable DNA Length-Sensitive Switch to Regulate Nucleosome Sliding

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SHANK1 is differentially expressed during development in CA1 hippocampal neurons and astrocytes

Recent studies have strongly suggested a role for the synaptic scaffolding protein SHANK1 in normal synaptic structure and signaling. Global SHANK1 knockout (SHANK1?/?) mice demonstrate reduced dendritic spine density, an immature dendritic spine phenotype and impairments in various cognitive tasks. SHANK1 overexpression is associated with increased dendritic spine size and impairments in fear conditioning. These studies suggest proper regulation of SHANK1 is crucial for appropriate synaptic structure and cognition. However, little is known regarding SHANK1's developmental expression in brain regions critical for learning. The current study quantified cell specific developmental expression of SHANK1 in the hippocampus, a brain region critically involved in various learning paradigms shown to be disrupted by SHANK1 dysregulation. Consistent with prior studies, SHANK1 was found to be strongly co‐expressed with dendritic markers, with significant increased co‐expression at postnatal day (P) 15, an age associated with increased synaptogenesis in the hippocampus. Interestingly, SHANK1 was also found to be expressed in astrocytes and microglia. To our knowledge, this is the first demonstration of glial SHANK1 localization; therefore, these findings were further examined via a glial purified primary cell culture fraction using magnetic cell sorting. This additional analysis further demonstrated that SHANK1 was expressed in glial cells, supporting our immunofluorescence co‐expression findings. Developmentally, astroglial SHANK1 co‐expression was found to be significantly elevated at P5 with a reduction into adulthood, while SHANK1 microglial co‐expression did not significantly change across development. These data collectively implicate a more global role for SHANK1 in mediating normal cellular signaling in the brain. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 363–373, 2018     

Validity of the Diplostomoidea and Diplostomida (Digenea,Platyhelminthes) upheld in phylogenomic analysis

Higher systematics within the Digenea, Carus 1863 have been relatively stable since a phylogenetic analysis of partial nuclear ribosomal markers (rDNA) led to the erection of the Diplostomida Olson, Cribb, Tkach, Bray, and Littlewood, 2003. However, recent mitochondrial (mt) genome phylogenies suggest this order might be paraphyletic. These analyses show members of two diplostomidan superfamilies are more closely related to the Plagiorchiida La Rue, 1957 than to other members of the Diplostomida. A recent phylogeny based on partial cytochrome c oxidase I also indicates one of the groups implicated, the Diplostomoidea Poirier, 1886, is non-monophyletic. To determine if these results were robust to additional taxon sampling, we analyzed mt genomes from seven diplostomoids in three families. To choose between phylogenetic alternatives based on mt genomes and the prior rDNA-based topology, we analyzed hundreds of ultra-conserved genomic elements assembled from shotgun sequencing. The Diplostomida was paraphyletic in the mt genome phylogeny but supported in the ultra-conserved genomic element phylogeny. We speculate this mitonuclear discordance is related to ancient, rapid radiation in the Digenea. Both ultra-conserved genomic elements and mt genomes support the monophyly of the Diplostomoidea and show congruent relationships within it. The Cyathocotylidae Mühling, 1898 are early diverging descendants of a paraphyletic clade of Diplostomidae Poirier, 1886, in which are nested members of the Strigeidae Railliet, 1919; the results support prior suggestions that the Crassiphialinae Sudarikov, 1960 will rise to the family level. Morphological traits of diplostomoid metacercariae appear to be more useful for differentiating clades than those of adults. We describe a new species of Cotylurus Szidat, 1928, resurrect a species of Hysteromorpha Lutz, 1931, and find support for a species of Alaria Schrank, 1788 of contested validity. Complete rDNA operons from seven diplostomoid species are provided as a resource for future studies.