Biology subjects

Guo, A.

Publications and source records attributed to Guo, A..

39 records · Page 3Linked to original sources

bioRxiv2018

De novo aging-related meganeurites: alteration of NADPH diaphorase positivity in the sacral spinal cord of the aged dog

The aging-related changes of NADPH-diaphorase (NADPH-d) in the spinal cord were studied in aged dogs. At all levels of the spinal cord examined, NADPH-d activities were present in neurons and fibers in the superficial dorsal horn, dorsal commissure and in neurons around the central canal. In addition, the sympathetic autonomic nucleus in the thoracic and rostral lumbar segments exhibited prominent NADPH-d cellular staining whereas the sacral parasympathetic nucleus (SPN) in the sacral segments was not well stained. Interestingly, we found abundant NADPH-d positive enlarged-diameter fibers termed megaloneurite, which characteristically occurred in the aged sacral segments, distributed in the dorsal gray commissure (DGC), lateral collateral pathway (LCP) the lateral fasciculi and the central canal compared with the cervical, thoracic and lumbar segments. The dense, abnormal NADPH-d megaloneurites occurred in extending from dorsal entry zone through lamina I along with the lateral boundary of the dorsal horn to the region of the SPN. These fibers were prominent in the S1-S3 segments but not in adjacent segments L5-L7 and Cx1 or in thoracolumbar segments and cervical segments. Double staining with GFAP, NeuN, CGRP, MAP2 and Iba1, NADPH-d megaloneurite colocalized with vasoactive intestinal peptide. Presumably, the megaloneurites may represent, in part, visceral afferent projections to the SPN and/or DGC. The NADPH-d megaloneurites in the aged sacral spinal cord indicated some anomalous changes in the neurites, which might account for a disturbance in the aging pathway of the autonomic and sensory nerve in the pelvic visceral organs.

neuroscience↗

bioRxiv2018

Phosphatidylinositol 3,5-Bisphosphate Regulates Yeast Vacuole Fusion at the Transition between trans-SNARE Complex Formation and Hemifusion

Phosphoinositides (PIs) regulate myriad cellular functions including membrane fusion, as exemplified by the yeast vacuole, which uses various PIs at different stages of fusion. In light of this, the effect of phos-phatidylinositol 3,5-bisphosphate [PI(3,5)P2] on vacuole fusion remains unknown. PI(3,5)P2 is made by the PI3P 5-kinase Fab1/PIKfyve and has been characterized as a regulator of vacuole fission during hyperosmotic shock where it interacts with the TRP family Ca2+ channel Yvc1. Here we demonstrate that exogenously added dioctanoyl (C8) PI(3,5)P2 abolishes homotypic vacuole fusion. This effect was not linked to interactions with Yvc1, as fusion was equally affected using yvc1{Delta} vacuoles. Thus, the effects of C8-PI(3,5)P2 on fusion versus fission operate through distinct mechanisms. Further testing showed that C8-PI(3,5)P2 inhibited vacuole fusion after the formation of trans-SNARE pairs. Although SNARE complex formation was unaffected we found that C8-PI(3,5)P2 strongly inhibited hemifusion. Overproduction of endogenous PI(3,5)P2 by the fab1T2250A hyperactive kinase mutant also inhibited at the hemifusion stage, bolstering the model in which PI(3,5)P2 inhibits fusion when present elevated levels. Taken together, this work identifies a novel function for PI(3,5)P2 as a negative regulator of vacuolar fusion. Moreover, it suggests that this lipid acts as a molecular switch between fission and fusion.

biochemistry↗

bioRxiv2018

A compromised gsdf signaling leads to gamatogenesis confusion and subfertility in medaka

Summary statementGsdf signals trigger the gamatogenesis, alter the somatic expression of Fsh/Lh receptors and brain type aromatase in medaka brain and gonad.\n\nAbstractGonadal soma-derived factor (gsdf) and anti-Mullerian hormone (amh) are somatic male determinants in several species of teleosts, although the mechanisms by which they trigger the indifferent germ cells into the male pathway remain unknown. This study aimed to decipher the roles of gsdf/amh in directing the sexual fate of germ cells using medaka as a model. Transgenic lines (TgcryG) that restrictively and persistently express a Gsdf-Gfp fusion protein in the lens and the hypothalamus-pituitary-gonad (HPG) axis, were generated under the control of a mouse {gamma}F-crystallin promoter. A high frequency (44.4%) of XX male sex reversals was obtained in TgcryG lines, indicating that signals of gsdf-expressing cells in HPG were enough for the spermatogenesis activation in the genetic females. Furthermore, all TgcryG XY individuals with endogenous gsdf depletion (named Sissy) displayed intersex (100%) with enlarged ovotestis in contrast to a giant ovary developed in XY gsdf deficiency. The heterogeneous expression of gsdf led to the confusion of gamatogenesis and ovotestis development, similar to some hotei (amhr2) mutants, suggests that the signaling balance of gsdf/amh is essential for proper gamatogenesis, maintaining sex steroid production and gonadotropin secretion, which are evolutionarily conserved across phyla.

evolutionary biology↗