Search results for "Ovum"
showing 10 items of 96 documents
Active hiding of social information from information-parasites
2014
Background: Coevolution between pairs of different kind of entities, such as providers and users of information, involves reciprocal selection pressures between them as a consequence of their ecological interaction. Pied flycatchers ( Ficedula hypoleuca ) have been shown to derive fitness benefits (larger clutches) when nesting in proximity to great tits ( Parus major ), presumably because they this way discover and obtain information about nesting sites. Tits suffer from the resulting association (smaller clutches). An arms race between the tits (information host) and the flycatchers (information parasite) could thus result . Great tits often cover eggs with nesting material before, but no…
How to escape from insect egg parasitoids : a review of potential factors explaining parasitoid absence across the Insecta
2020
The egg is the first life stage directly exposed to the environment in oviparous animals, including many vertebrates and most arthropods. Eggs are vulnerable and prone to mortality risks. In arthropods, one of the most common egg mortality factors is attack from parasitoids. Yet, parasitoids that attack the egg stage are absent in more than half of all insect (sub)orders. In this review, we explore possible causes explaining why eggs of some insect taxa are not parasitized. Many insect (sub)orders that are not attacked by egg parasitoids lack herbivorous species, with some notable exceptions. Factors we consider to have led to escape from egg parasitism are parental egg care, rapid egg deve…
Composition and Genetic Diversity of Mosquitoes (Diptera: Culicidae) on Islands and Mainland Shores of Kenya's Lakes Victoria and Baringo.
2016
The Lake Baringo and Lake Victoria regions of Kenya are associated with high seroprevalence of mosquito-transmitted arboviruses. However, molecular identification of potential mosquito vector species, including morphologically identified ones, remains scarce. To estimate the diversity, abundance, and distribution of mosquito vectors on the mainland shores and adjacent inhabited islands in these regions, we collected and morphologically identified adult and immature mosquitoes and obtained the corresponding sequence variation at cytochrome c oxidase 1 (COI) and internal transcribed spacer region 2 (ITS2) gene regions. A total of 63 species (including five subspecies) were collected from both…
Limited proteolysis by acrosin affects sperm-binding and mechanical resilience of the mouse zona pellucida.
2021
Abstract The encounter of oocyte and sperm is the key event initiating embryonic development in mammals. Crucial functions of this existential interaction are determined by proteolytic enzymes, such as acrosin, carried in the sperm head acrosome, and ovastacin, stored in the oocyte cortical granules. Ovastacin is released upon fertilisation to cleave the zona pellucida, a glycoprotein matrix surrounding the oocyte. This limited proteolysis hardens the oocyte envelope, and thereby provides a definitive block against polyspermy and protects the developing embryo. On the other hand, acrosin, the renowned and most abundant acrosomal protease, has been thought to enable sperm to penetrate the oo…
Trans-generational immune priming in the mealworm beetle protects eggs through pathogen-dependent mechanisms imposing no immediate fitness cost for t…
2018
8 pages; International audience; Immune-challenged mothers can improve their offspring immunity through trans-generational immune priming (TGIP). In insects, TGIP endows the offspring with lifetime immunity, including the eggs, which are likely exposed soon after maternal infection. Egg protection may rely on the transfer of maternal immune effectors to the egg or/and the induction of egg immune genes. These respective mechanisms are assumed to have early-life fitness costs of different magnitude for the offspring. We provide evidence in the mealworm beetle Tenebrio molitor that enhanced egg immunity following a maternal immune challenge is achieved by both of these mechanisms but in a path…
Embryo multinucleation at the two-cell stage is an independent predictor of intracytoplasmic sperm injection outcomes.
2016
Objective To determine the prognostic impact of the nuclear status at the two-cell stage on intracytoplasmic sperm injection (ICSI) outcomes. Design Retrospective study. Setting Hospital. Patient(s) Only ICSI cycles with time-lapse monitoring of transferred embryos with known implantation/delivery data from November 2012 to December 2014 were included. A total of 2,449 embryos were assessed for multinucleation rates at the two- and four-cell stage, and 608 transferred embryos were studied for ICSI outcomes. Intervention(s) None. Main Outcome Measure(s) Implantation rate (IR) and live birth rate (LBR) according to the number of multinucleated blastomeres at the two-cell stage: none (Without-…
Effect of oocyte vitrification on embryo quality: time-lapse analysis and morphokinetic evaluation.
2017
To analyze whether oocyte vitrification may affect subsequent embryo development from a morphokinetic standpoint by means of time-lapse imaging.Observational cohort study.University-affiliated private IVF center.Ovum donation cycles conducted with the use of vitrified (n = 631 cycles; n = 3,794 embryos) or fresh oocytes (n = 1,359 cycles; n = 9,935 embryos) over 2 years.None.Embryo development was analyzed in a time-lapse imaging incubator. The studied variables included time to 2 cells (t2), 3 cells (t3), 4 cells (t4), 5 cells (t5), morula (tM), and cavitated, early, and hatching blastocyst (tB, tEB, tHB) as well as 2nd cell cycle duration (cc2 = t3 - t2). All of the embryos were classifie…
Trichuris trichiura egg extract proteome reveals potential diagnostic targets and immunomodulators.
2021
The proteomic analysis was performed at the proteomics facility of SCSIE, University of Valencia (Burjassot, Spain) that belongs to ProteoRed, PRB2-ISCIII, Madrid, Spain. We also thank Dr. Tatiana Corey, Dr. Amy Beierschmitt and Dr. Pompei Bolfa for their support during sample collection.
On the adenosintriphosphatase activity of the particulates of the egg of the sea urchinParacentrotus lividus
1957
I particolati delle uova vergini di riccio di mare possono essere separati, a mezzo della centrifugazione differenziale, in due frazioni, una fortemente ed una scarsamente pigmentata. La prima mostra una attivita ATPasica attivata da Mg con un massimo a pH 8.2; il massimo della seconda e invece a pH 6.4. Nelle preparazioni contenenti i due tipi di particolati si ritrovano i due massimi.
Cumulative newborn rates increase with the total number of transferred embryos according to an analysis of 15,792 ovum donation cycles
2011
Objective To measure the success of in vitro fertilization (IVF) of donated ova according to cumulative newborn rates (CNBR) per number of embryos required to achieve at least one newborn (EmbR), considering in addition the relevance of age and infertility etiology. Design Survival curves and Kaplan-Meier methods were employed to analyze CNBR with respect to the number of EmbR in a retrospective cohort of oocyte donation recipients. Setting University-affiliated infertility center. Patient(s) Infertile couples undergoing IVF with oocyte donation. Intervention(s) None. Main Outcome Measure(s) CNBR per EmbR. Result(s) The CNBR increased radically (up to 64.8%) between 1 and 5 EmbR, moderately…