Search results for "Litter"
showing 10 items of 315 documents
Effect of delayed breeding on the reproductive performance of female mice
2003
The aim of the present study was to determine, in the mouse, whether maintaining females as virgins until an advanced reproductive age was associated with decreased reproductive performance and reproductive lifespan compared with females of the same age that were first mated with males at an earlier reproductive age. Randomly selected virgin hybrid (C57BL/6JIco female × CBA/JIco male) female mice were housed individually with a randomly selected 12- to 14-week-old hybrid male either at the age of 28 weeks (normal breeding group; n = 20) or 51 weeks (delayed breeding group; n = 23) for the rest of their reproductive life. Females were checked once daily to determine the day of parturition an…
Maternal investment in relation to sex ratio and offspring number in a small mammal – a case for Trivers and Willard theory?
2009
1. Optimal parental sex allocation depends on the balance between the costs of investing into sons vs. daughters and the benefits calculated as fitness returns. The outcome of this equation varies with the life history of the species, as well as the state of the individual and the quality of the environment. 2. We studied maternal allocation and subsequent fecundity costs of bank voles, Myodes glareolus, by manipulating both the postnatal sex ratio (all-male/all-female litters) and the quality of rearing environment (through manipulation of litter size by -2/+2 pups) of their offspring in a laboratory setting. 3. We found that mothers clearly biased their allocation to female rather than ma…
HORMONAL MANIPULATION OF OFFSPRING NUMBER: MATERNAL EFFORT AND REPRODUCTIVE COSTS
2002
We used exogenous gonadotropin hormones to physiologically enlarge litter size in the bank vole (Clethrionomys glareolus). This method allowed the study design to include possible production costs of reproduction and a trade-off between offspring number and body size at birth. Furthermore, progeny rearing and survival and postpartum survival of the females took place in outdoor enclosures to capture salient naturalistic effects that might be present during the fall and early winter. The aim of the study was to assess the effects of the manipulation on the growth and survival of the offspring and on the reproductive effort, survival, and future fecundity of the mothers. Mean offspring body s…
Oral administration of pharmacological doses of Vitamins C and E reduces reproductive fitness and impairs the ovarian and uterine functions of female…
2002
This study aims to ascertain whether oral administration of pharmacological doses of Vitamins C and E has any detrimental effect on reproductive fitness of female mice. We fed hybrid female mice from the first day of weaning a standard diet supplemented or not supplemented with pharmacological doses of Vitamins C and E. At the age of 28 weeks, we individually caged females with a male for the rest of their reproductive life. We performed a series of mating experiments to ascertain the number of oocytes ovulated and the potential for embryo development in vitro to the blastocyst stage and in vivo to Day 12 of gestation. The antioxidant diet decreased the frequency of litters, litter size, to…
Pregnancy after allogeneic uterus transplantation in the rat: perinatal outcome and growth trajectory
2014
Objective To investigate whether allogeneic uterine grafts in a rat model, with tacrolimus immunosuppression, can harbor pregnancies that result in offspring with normal postnatal growth. Design Experimental animal study. Setting University hospital. Animal(s) Lewis rats as uterus donors and Piebald-Virol-Glaxo rats as recipients. Intervention(s) Animals were allocated to one of the following three groups: allogeneic uterus transplantation with end-to-side anastomosis to the external iliac vessels and immunosuppression with tacrolimus (UT+Tac; n=10); sham surgery and immunosuppression with tacrolimus (Sham+Tac; n=10); or sham surgery (Sham; n=10). The rats were subsequently introduced to ma…
A Portfolio Problem with Uncertainty
2000
In this paper we present two models for cash flow matching with an uncertain level of payments at each due date. To solve the problem of minimising the initial investment we use the scenario method proposed by Dembo, and the robust optimisation method proposed by Mulvey et al. We unify these optimisation methods in a general co-ordinated model that guarantees a match under every scenario. This general model is also a multi-objective programming problem. We illustrate this methodology in a problem with several scenarios.
Optical flip-flop memory and routing operation based on polarization bistability in optical fiber
2014
A polarization bistability and hysteresis cycle phenomenon is demonstrated in optical fibers thanks to a counter-propagating four-wave mixing interaction. Based on this process, we successfully report the proof-of-principle of an optical flip-flop memory and a 10-Gbit/s routing operation.
<title>Dot-matrix holographic recording in amorphous chalcogenide films</title>
2006
We have developed PC controlled dot-matrix holographic recording system based on the CW diode pumped YAG:Nd SHG laser (wavelength 532 nm, power 30mW,) modulated electronically with TTL signals. Two-beam technique has been used with convergence angle 30o and PC controlled incident beam plane rotation 0-360o. Optical system consists of beam splitter, 40mm focus length forming cylindrical lens and 40mm focusing lens. Characteristic parameters of experimental equipment are following: spot size - 50-200 micrometers, direct laser writing area, limited by x-y positioning system, was 70mm x 70mm, number of writing head rotation positions up to 256 (8 bit), time of each exposure - 1-1000 msec. As th…
Simultaneous dual mode imaging platform in lensless holographic microscopy
2019
We present a novel layout capable of dual mode imaging in real time with different magnifications and resolution capabilities in lensless microscopy based on wavelength multiplexing. Experiments using static and dynamic samples are included.
Marine debris ingestion in loggerhead sea turtles, Caretta caretta, from the Western Mediterranean
2002
Marine debris represents an important threat for sea turtles, but information on this topic is scarce in some areas, such as the Mediterranean sea. This paper quantifies marine debris ingestion in 54 juvenile loggerhead sea turtles (Caretta caretta) illegally captured by fishermen in Spanish Mediterranean waters. Curved carapace length was measured, necropsies were performed and debris abundance and type was recorded. Different types of debris appeared in the gastrointestinal tract of 43 turtles (79.6%), being plastics the most frequent (75.9%). Tar, paper, Styrofoam, wood, reed, feathers, hooks, lines, and net fragments were also present. A regression analysis showed that the volume of deb…