Browsing by Subject "VERTEBRATE"

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  • Tammimies, Kristiina; Bieder, Andrea; Lauter, Gilbert; Sugiaman-Trapman, Debora; Torchet, Rachel; Hokkanen, Marie-Estelle; Burghoorn, Jan; Castrén, Eero; Kere, Juha; Tapia-Paez, Isabel; Swoboda, Peter (2016)
    DYX1C1, DCDC2, and KIAA0319 are three of the most replicated dyslexia candidate genes (DCGs). Recently, these DCGs were implicated in functions at the cilium. Here, we investigate the regulation of these DCGs by Regulatory Factor X transcription factors (RFX TFs), a gene family known for transcriptionally regulating ciliary genes. We identify conserved X-box motifs in the promoter regions of DYX1C1, DCDC2, and KIAA0319 and demonstrate their functionality, as well as the ability to recruit RFX TFs using reporter gene and electrophoretic mobility shift assays. Furthermore, we uncover a complex regulation pattern between RFX1, RFX2, and RFX3 and their significant effect on modifying the endogenous expression of DYX1C1 and DCDC2 in a human retinal pigmented epithelial cell line immortalized with hTERT (hTERT-RPE1). In addition, induction of ciliogenesis increases the expression of RFX TFs and DCGs. At the protein level, we show that endogenous DYX1C1 localizes to the base of the cilium, whereas DCDC2 localizes along the entire axoneme of the cilium, thereby validating earlier localization studies using overexpression models. Our results corroborate the emerging role of DCGs in ciliary function and characterize functional noncoding elements, X-box promoter motifs, in DCG promoter regions, which thus can be targeted for mutation screening in dyslexia and ciliopathies associated with these genes.
  • Feldman, Tatiana; Yakovleva, Marina; Viljanen, Martta Leena Maria; Lindström, Magnus; Donner, Kristian; Ostrovsky, M.A. (2020)
    We have studied dark-adaptation at three levels in the eyes of the crustaceanMysis relictaover 2-3 weeks after exposing initially dark-adapted animals to strong white light: regeneration of 11-cisretinal through the retinoid cycle (by HPLC), restoration of native rhodopsin in photoreceptor membranes (by MSP), and recovery of eye photosensitivity (by ERG). We compare two model populations ("Sea", S-p, and "Lake", L-p) inhabiting, respectively, a low light and an extremely dark environment. 11-cisretinal reached 60-70% of the pre-exposure levels after 2 weeks in darkness in both populations. The only significant L-p/S(p)difference in the retinoid cycle was that L(p)had much higher levels of retinol, both basal and light-released. In S-p, rhodopsin restoration and eye photoresponse recovery parallelled 11-cisretinal regeneration. In L-p, however, even after 3 weeks only ca. 25% of the rhabdoms studied had incorporated new rhodopsin, and eye photosensitivity showed only incipient recovery from severe depression. The absorbance spectra of the majority of the L(p)rhabdoms stayed constant around 490-500 nm, consistent with metarhodopsin II dominance. We conclude that sensitivity recovery of S(p)eyes was rate-limited by the regeneration of 11-cisretinal, whilst that of L(p)eyes was limited by inertia in photoreceptor membrane turnover.
  • Li, Xiaofei; Wang, Shengnan; Prather, Chelse; Wan, Ho Yi; Zhu, Hui; Nummi, Petri; Inbar, Moshe; Gao, Qiang; Wang, Deli; Zhong, Zhiwei (2021)
    Large herbivores often co-occur and share plant resources with herbivorous insects in grassland ecosystems; yet, how they interact with each other remains poorly understood. We conducted a series of field experiments to investigate whether and how large domestic herbivores (sheep; Ovis aries) may affect the abundance of a common herbivorous insect (aphid; Hyalopterus pruni) in a temperate grassland of northeast China. Our exclosure experiment showed that 3 years (2010-2012) of sheep grazing had led to 86% higher aphid abundance compared with ungrazed sites. Mechanistically, this facilitative effect was driven by grazing altering the plant community, rather than by changes in food availability and predator abundance for aphids. Sheep significantly altered plant community by reducing the abundance of unpalatable forbs for the aphids. Our small-scale forb removal experiment revealed an "associational plant defense" by forbs which protect the grass Phragmites australis from being attacked by the aphids. However, selective grazing on forbs by sheep indirectly disrupted such associational plant defense, making P. australis more susceptible to aphids, consequentially increasing the density of aphids. These findings provide a novel mechanistic explanation for the effects of large herbivores on herbivorous insects by linking selective grazing to plant community composition and the responses of insect populations in grassland ecosystems.