12 research outputs found
Cellular response of Parachlorella kessleri to a solid surface culture environment
Attached culture allows high biomass productivity and is a promising biomass cultivating system because neither a huge facility area nor a large volume of culture medium are needed. This study investigates photosynthetic and transcriptomic behaviors in Parachlorella kessleri cells on a solid surface after their transfer from liquid culture to elucidate the physiological and gene-expression regulatory mechanisms that underlie their vigorous proliferation. The chlorophyll content shows a decrease at 12 h after the transfer; however, it has fully recovered at 24 h, suggesting temporary decreases in the amounts of light harvesting complexes. On PAM analysis, it is demonstrated that the effective quantum yield of PSII decreases at 0 h right after the transfer, followed by its recovery in the next 24 h. A similar changing pattern is observed for the photochemical quenching, with the PSII maximum quantum yield remaining at an almost unaltered level. Non-photochemical quenching was increased at both 0 h and 12 h after the transfer. These observations suggest that electron transfer downstream of PSII but not PSII itself is only temporarily damaged in solid-surface cells just after the transfer, with light energy in excess being dissipated as heat for PSII protection. It thus seems that the photosynthetic machinery acclimates to high-light and/or dehydration stresses through its temporal size-down and functional regulation that start right after the transfer. Meanwhile, transcriptomic analysis by RNA-Seq demonstrates temporary upregulation at 12 h after the transfer as to the expression levels of many genes for photosynthesis, amino acid synthesis, general stress response, and ribosomal subunit proteins. These findings suggest that cells transferred to a solid surface become stressed immediately after transfer but can recover their high photosynthetic activity through adaptation of photosynthetic machinery and metabolic flow as well as induction of general stress response mechanisms within 24 h
Transcription factors Mix1 and VegT, relocalization ofvegtmRNA, and conserved endoderm and dorsal specification in frogs
Photograph of the exterior of the Ponca Theatre
Additional file 1: Table S1. of Cell type-specific effects of p27KIP1 loss on retinal development
Antibodies. Table S2. Primers. (DOCX 17 kb
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Endodermal Maternal Transcription Factors Establish Super-Enhancers during Zygotic Genome Activation.
Elucidation of the sequence of events underlying the dynamic interaction between transcription factors and chromatin states is essential. Maternal transcription factors function at the top of the regulatory hierarchy to specify the primary germ layers at the onset of zygotic genome activation (ZGA). We focus on the formation of endoderm progenitor cells and examine the interactions between maternal transcription factors and chromatin state changes underlying the cell specification process. Endoderm-specific factors Otx1 and Vegt together with Foxh1 orchestrate endoderm formation by coordinated binding to select regulatory regions. These interactions occur before the deposition of enhancer histone marks around the regulatory regions, and these TFs recruit RNA polymerase II, regulate enhancer activity, and establish super-enhancers associated with important endodermal genes. Therefore, maternal transcription factors Otx1, Vegt, and Foxh1 combinatorially regulate the activity of super-enhancers, which in turn activate key lineage-specifying genes during ZGA
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Endodermal Maternal Transcription Factors Establish Super-Enhancers during Zygotic Genome Activation.
Elucidation of the sequence of events underlying the dynamic interaction between transcription factors and chromatin states is essential. Maternal transcription factors function at the top of the regulatory hierarchy to specify the primary germ layers at the onset of zygotic genome activation (ZGA). We focus on the formation of endoderm progenitor cells and examine the interactions between maternal transcription factors and chromatin state changes underlying the cell specification process. Endoderm-specific factors Otx1 and Vegt together with Foxh1 orchestrate endoderm formation by coordinated binding to select regulatory regions. These interactions occur before the deposition of enhancer histone marks around the regulatory regions, and these TFs recruit RNA polymerase II, regulate enhancer activity, and establish super-enhancers associated with important endodermal genes. Therefore, maternal transcription factors Otx1, Vegt, and Foxh1 combinatorially regulate the activity of super-enhancers, which in turn activate key lineage-specifying genes during ZGA
Tissue-Specific Gene Inactivation in Xenopus laevis : Knockout of lhx1 in the Kidney with CRISPR/Cas9
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here by permission of Genetics Society of America for personal use, not for redistribution. The definitive version was published in Genetics 208 (2018): 673-686, doi:10.1534/genetics.117.300468.Studying genes involved in organogenesis is often difficult because many of these
genes are also essential for early development. The allotetraploid frog, Xenopus laevis,
is commonly used to study developmental processes, but because of the presence of
two homeologs for many genes, it has been difficult to use as a genetic model. Few
studies have successfully used CRISPR in amphibians, and currently there is no tissue-targeted knockout strategy described in Xenopus. The goal of this study is to determine
whether CRISPR/Cas9-mediated gene knockout can be targeted to the Xenopus kidney
without perturbing essential early gene function. We demonstrate that targeting CRISPR
gene editing to the kidney and the eye of F0 embryos is feasible. Our study shows that
knockout of both homeologs of lhx1 results in the disruption of kidney development and
function but does not lead to early developmental defects. Therefore, targeting of
CRISPR to the kidney may not be necessary to bypass the early developmental defects
reported upon disruption of Lhx1 protein expression or function by morpholinos,
antisense RNA, or dominant negative constructs. We also establish a control for
CRISPR in Xenopus by editing a gene (slc45a2) that when knocked out results in
albinism without altering kidney development. This study establishes the feasibility of
tissue-specific gene knockout in Xenopus, providing a cost effective and efficient
method for assessing the roles of genes implicated in developmental abnormalities that
is amenable to high-throughput gene or drug screening techniques.These studies were supported by a National Institutes
of Health (NIH) KO1 grant (K01DK092320 to R.K.M.), startup funding from the
Department of Pediatrics 424 Pediatric Research Center at the University of Texas
McGovern Medical School (to R.K.M.), an NIH National Xenopus Resource Center
grant (P40OD010997 to M.E.H.), and an NIH R01 grant (R01HD084409 to M.E.H.)