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Fredrik Elinder, Michael Madeja, Hugo Zeberg, Peter Århem
The transmembrane voltage needed to open different voltage-gated K (Kv) channels differs by up to 50 mV from each other. In this study we test the hypothesis that the channels' voltage dependences to a large extent are set by charged amino-acid residues of the extracellular linkers of the Kv channels, which electrostatically affect the charged amino-acid residues of the voltage sensor S4. Extracellular cations shift the conductance-versus-voltage curve, G(V), by interfering with these extracellular charges...
October 18, 2016: Biophysical Journal
Wang Zheng, Jungwoo Yang, Erwan Beauchamp, Ruiqi Cai, Shaimaa Hussein, Laura Hofmann, Qiang Li, Veit Flockerzi, Luc G Berthiaume, Jingfeng Tang, Xing-Zhen Chen
Transient receptor potential polycystin-3 (TRPP3) is a cation channel activated by calcium and proton and is involved in hedgehog signaling, intestinal development, and sour tasting. How TRPP3 channel function is regulated remains poorly understood. By N-terminal truncation mutations, electrophysiology and Xenopus oocytes expression, we first identified fragment D21-S42 to be functionally important. We then found that deletion mutant Δ1-36 (TRPP3 missing fragment M1-R36) has similar function as wild-type TRPP3 while Δ1-38 is functionally dead, suggesting the importance of V37 or C38...
October 17, 2016: Journal of Biological Chemistry
William R Holmes, Adriana E Golding, William M Bement, Leah Edelstein-Keshet
Rho GTPases are regulatory proteins whose patterns on the surface of a cell affect cell polarization, cell motility and repair of single-cell wounds. The stereotypical patterns formed by two such proteins, Rho and Cdc42, around laser-injured frog oocytes permit experimental analysis of GTPase activation, inactivation, segregation and crosstalk. Here, we review the development and analysis of a spatial model of GTPase dynamics that describe the formation of concentric zones of Rho and Cdc42 activity around wounds, and describe how this model has provided insights into the roles of the GTPase effector molecules protein kinase C (PKCβ and PKCη) and guanosine nucleotide dissociation inhibitor (GDI) in the wound response...
October 6, 2016: Interface Focus
Solange Abdulnour-Nakhoul, Trang Le, Edd Rabon, L Lee Hamm, Nazih L Nakhoul
Renal Rhbg is localized to the basolateral membrane of intercalated cells and is involved in NH3/NH4+ transport. The structure of Rhbg is not yet resolved however a high-resolution crystal structure of AmtB, a bacterial homologue of Rh, has been determined. We aligned the sequence of Rhbg to AmtB and identified important sites of Rhbg that may affect transport. Our analysis positioned three conserved amino acids, Histidine-183 (H183), Histidine-342 (H342) and Tryptophan-230 (W230), within the hydrophobic pore where they presumably serve to control NH3 transport...
September 28, 2016: American Journal of Physiology. Renal Physiology
Jana Jankovicova, Michaela Frolikova, Natasa Sebkova, Michal Simon, Petra Cupperova, Denisa Lipcseyova, Katarina Michalkova, Lubica Horovska, Radislav Sedlacek, Pavel Stopka, Jana Antalikova, Katerina Dvorakova-Hortova
Sperm-egg interaction and fusion represents a key moment of fertilization and it would not happen in mammals without the interaction of the tetraspanin superfamily members including protein CD81. A detailed immunohistochemical localization of CD81 was monitored on bovine oocytes of different maturation stages, as well as during early embryogenesis. There was also a CD81characterization on bovine and mouse sperm carried out. On bovine eggs, CD81 was detected on the plasma membrane of the germinal vesicle, metaphase I and metaphase II oocytes...
September 27, 2016: Reproduction: the Official Journal of the Society for the Study of Fertility
Izabela Jędrzejowska, Kamil Szymusiak, Marta Mazurkiewicz-Kania, Arnold Garbiec
Scorpions are viviparous matrotrophic arthropods. Both, fertilization and embryonic development occur in the female gonad called ovariuterus. Two distinct reproductive patterns are recognized among scorpions: apoikogenic and katoikogenic. In the ovariuterus of apoikogenic scorpions growing oocytes protrude from the ovarian wall and continue previtellogenic and vitellogenic growth on the gonad surface being accompanied by the follicular cells that cover the oocyte surface, and, in most families, the stalk cells that join the oocyte with the ovariuterus wall...
September 27, 2016: Arthropod Structure & Development
Isabella Ellinger
Active placental transport of maternal serum calcium (Ca(2+)) to the offspring is pivotal for proper development of the fetal skeleton as well as various organ systems. Moreover, extracellular Ca(2+) levels impact on distinct processes in mammalian reproduction. The calcium-sensing receptor (CaSR) translates changes in extracellular Ca(2+)-concentrations into cellular reactions. This review summarizes current knowledge on the expression of CaSR and its putative functions in reproductive organs. CaSR was detected in placental cells mediating materno-fetal Ca(2+)-transport such as the murine intraplacental yolk sac (IPYS) and the human syncytiotrophoblast...
2016: Frontiers in Physiology
Johan-Till Pougnet, Benjamin Compans, Audrey Martinez, Daniel Choquet, Eric Hosy, Eric Boué-Grabot
Plasticity at excitatory synapses can be induced either by synaptic release of glutamate or the release of gliotransmitters such as ATP. Recently, we showed that postsynaptic P2X2 receptors activated by ATP released from astrocytes downregulate synaptic AMPAR, providing a novel mechanism by which glial cells modulate synaptic activity. ATP- and lNMDA-induced depression in the CA1 region of the hippocampus are additive, suggesting distinct molecular pathways. AMPARs are homo-or hetero-tetramers composed of GluA1-A4...
2016: Scientific Reports
Evan C Ray, Jingxin Chen, Tanika N Kelly, Jiang He, L Lee Hamm, Dongfeng Gu, Lawrence C Shimmin, James E Hixson, Dabeeru C Rao, Shaohu Sheng, Thomas R Kleyman
Mutations in genes encoding subunits of the epithelial Na(+) channel (ENaC) can cause early-onset familial hypertension, demonstrating the importance of this channel in modulating blood pressure. It remains unclear whether other genetic variants resulting in subtler alterations of channel function result in hypertension or altered sensitivity of blood pressure to dietary salt. This study sought to identify functional human ENaC variants, to examine how these variants alter channel activity, and to explore whether these variants are associated with altered sensitivity of blood pressure to dietary salt...
August 31, 2016: American Journal of Physiology. Renal Physiology
Chakravarthi Chintalapati, Thorsten Keller, Thomas D Mueller, Valentin Gorboulev, Nadine Schäfer, Ilona Zilkowski, Maike Veyhl-Wichmann, Dietmar Geiger, Jürgen Groll, Hermann Koepsell
Na(+)-d-glucose cotransporter 1 (SGLT1) is rate-limiting for glucose absorption in the small intestine. Shortly after intake of glucose-rich food, SGLT1 abundance in the luminal membrane of the small intestine is increased. This upregulation occurs via glucose-induced acceleration of the release of SGLT1-containing vesicles from the trans-Golgi network (TGN), which is regulated by a domain of protein RS1 (RSC1A1) named RS1-Reg. Dependent on phosphorylation, RS1-Reg blocks release of vesicles containing SGLT1 or concentrative nucleoside transporter 1...
November 2016: Molecular Pharmacology
Daniel Dilg, Rasha Noureldin M Saleh, Sarah Elizabeth Lee Phelps, Yoann Rose, Laurent Dupays, Cian Murphy, Timothy Mohun, Robert H Anderson, Peter J Scambler, Ariane L A Chapgier
Chromatin remodelling is essential for cardiac development. Interestingly, the role of histone chaperones has not been investigated in this regard. HIRA is a member of the HUCA (HIRA/UBN1/CABIN1/ASF1a) complex that deposits the variant histone H3.3 on chromatin independently of replication. Lack of HIRA has general effects on chromatin and gene expression dynamics in embryonic stem cells and mouse oocytes. Here we describe the conditional ablation of Hira in the cardiogenic mesoderm of mice. We observed surface oedema, ventricular and atrial septal defects and embryonic lethality...
2016: PloS One
Hatice Duygu Saatcioglu, Ileana Cuevas, Diego H Castrillon
In mammals, females are born with finite numbers of oocytes stockpiled as primordial follicles. Oocytes are "reawakened" via an ovarian-intrinsic process that initiates their growth. The forkhead transcription factor Foxo3 controls reawakening downstream of PI3K-AKT signaling. However, the identity of the presumptive upstream cell surface receptor controlling the PI3K-AKT-Foxo3 axis has been questioned. Here we show that the receptor tyrosine kinase Kit controls reawakening. Oocyte-specific expression of a novel constitutively-active KitD818V allele resulted in female sterility and ovarian failure due to global oocyte reawakening...
August 2016: PLoS Genetics
Heidi Kemiläinen, Marion Adam, Jenni Mäki-Jouppila, Pauliina Damdimopoulou, Anastasios E Damdimopoulos, Juha Kere, Outi Hovatta, Teemu D Laajala, Tero Aittokallio, Jerzy Adamski, Henrik Ryberg, Claes Ohlsson, Leena Strauss, Matti Poutanen
The hydroxysteroid (17beta) dehydrogenase (HSD17B)12 gene belongs to the hydroxysteroid (17β) dehydrogenase superfamily, and it has been implicated in the conversion of estrone to estradiol as well as in the synthesis of arachidonic acid (AA). AA is a precursor of prostaglandins, which are involved in the regulation of female reproduction, prompting us to study the role of HSD17B12 enzyme in the ovarian function. We found a broad expression of HSD17B12 enzyme in both human and mouse ovaries. The enzyme was localized in the theca interna, corpus luteum, granulosa cells, oocytes, and surface epithelium...
October 2016: Endocrinology
Aaron Teo, James R Guest, Mei Lin Neo, Kareen Vicentuan, Peter A Todd
Most studies of coral reproductive biology to date have focused on oocyte numbers and sizes. Only one (ex situ) study has enumerated sperm numbers, even though these data have multiple potential applications. We quantified total coral sperm and eggs per gamete bundle collected from six species in situ during a synchronous spawning event in Singapore. Egg-sperm bundles were captured midwater as they floated towards the surface after being released by the colony. For each sample, a semi-transparent soft plastic bottle was squeezed and released to create a small suction force that was used to 'catch' the bundles...
2016: PeerJ
Mohammad Hossein Nasr Esfahani, Mohammad Reza Deemeh, Marziyeh Tavalaee, Mohammad Hadi Sekhavati, Hamid Gourabi
BACKGROUND: Selection of sperm for intra-cytoplasmic sperm injection (ICSI) is usually considered as the ultimate technique to alleviate male-factor infertility. In routine ICSI, selection is based on morphology and viability which does not necessarily preclude the chance injection of DNA-damaged or apoptotic sperm into the oocyte. Sperm with high negative surface electrical charge, named "Zeta potential", are mature and more likely to have intact chromatin. In addition, X-bearing spermatozoa carry more negative charge...
July 2016: International Journal of Fertility & Sterility
Toshiaki Hino, Yuko Muro, Miwa Tamura-Nakano, Masaru Okabe, Hiroyuki Tateno, Ryuzo Yanagimachi
Although 90%-100% of mouse oocytes can be fertilized in vitro with capacitated spermatozoa within 1 h after insemination, oocytes within the oviduct are fertilized one by one over a period of several hours. In vitro experiments showed that both acrosome-intact and acrosome-reacted spermatozoa entered the cumulus oophorus, but that acrosome-reacted spermatozoa reached the surface of oocytes more readily than acrosome-intact spermatozoa. During the period of fertilization within the oviduct, acrosome-reacted spermatozoa were seen throughout the isthmus, but with higher incidence in the upper than in the mid- and lower segments of the isthmus...
September 2016: Biology of Reproduction
Meena Murthy, Thimo Kurz, Kevin M O'Shaughnessy
Familial hyperkalemic hypertension (FHHt) is a rare inherited form of salt-dependent hypertension caused by mutations in proteins that regulate the renal Na(+)-Cl(-) cotransporter NCC Mutations in four genes have been reported to cause FHHt including CUL3 (Cullin3) that encodes a component of a RING E3 ligase. Cullin-3 binds to WNK kinase-bound KLHL3 (the substrate recognition subunit of the ubiquitin ligase complex) to promote ubiquitination and proteasomal degradation of WNK kinases. Deletion of exon 9 from CUL3 (affecting residues 403-459, CUL3(Δ403-459)) causes a severe form of FHHt (PHA2E) that is recapitulated closely in a knock-in mouse model...
July 2016: Physiological Reports
Weston A Nichols, Brandon J Henderson, Christopher B Marotta, Caroline Y Yu, Chris Richards, Dennis A Dougherty, Henry A Lester, Bruce N Cohen
A number of mutations in α4β2-containing (α4β2*) nicotinic acetylcholine (ACh) receptors (nAChRs) are linked to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), including one in the β2 subunit called β2V287L. Two α4β2* subtypes with different subunit stoichiometries and ACh sensitivities co-exist in the brain, a high-sensitivity subtype with (α4)2(β2)3 subunit stoichiometry and a low-sensitivity subtype with (α4)3(β2)2 stoichiometry. The α5 nicotinic subunit also co-assembles with α4β2 to form a high-sensitivity α5α4β2 nAChR...
2016: PloS One
V Mazzei, F Sinatra, G Villaggio, G Longo
The ultrastructural study carried out on (a) oocytes of Armadillidium vulgare during vitellogenesis, (b) mature eggs taken from the ovaries during the parturial moult of the posterior half of the body, and (c) fertilized eggs collected within a few hours of their release into the brood pouch, has clearly demonstrated that before the fertilization the chorion is the only envelope present in the egg of oniscidean isopods. In the mature eggs, the chorion appears as a uniformly electron-dense lamina, about 0.4-0...
September 2016: Microscopy Research and Technique
Halil Aydin, Azmiri Sultana, Sheng Li, Annoj Thavalingam, Jeffrey E Lee
Fertilization is an essential biological process in sexual reproduction and comprises a series of molecular interactions between the sperm and egg. The fusion of the haploid spermatozoon and oocyte is the culminating event in mammalian fertilization, enabling the creation of a new, genetically distinct diploid organism. The merger of two gametes is achieved through a two-step mechanism in which the sperm protein IZUMO1 on the equatorial segment of the acrosome-reacted sperm recognizes its receptor, JUNO, on the egg surface...
June 23, 2016: Nature
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