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71.
Ewa Sell-Kubiak Klaus Wimmers Henry Reyer Tomasz Szwaczkowski 《Journal of applied genetics》2017,58(4):487-498
Currently, optimization of feed efficiency is one of the main challenges in improvement programs of livestock and poultry genetics. The objective of this review is to present the genetic aspects of feed efficiency related traits in meat-type chicken and possible ways to reduce the environmental impact of poultry meat production with effective breeding. Basic measures of feed efficiency are defined and the genetic background of these traits, including a review of heritabilities is described. Moreover, a number of genomic regions and candidate genes determining feed efficiency traits of broilers that were detected over the past decades are described. Classical and genomic selection strategies for feed efficiency in the context of its relationships with other performance traits are discussed as well. Finally, future strategies to improve feed digestibility are described as it is expected that they will decrease wastes and greenhouse gas emission. Further genetic improvement of feed efficiency, should be examined jointly with appropriate feeding strategies in broilers. 相似文献
72.
DNA synthesis and the incorporation of labeled iris cells into the lens during lens regeneration in adult newts 总被引:3,自引:0,他引:3
R W Reyer 《Developmental biology》1971,24(4):533-558
73.
Isabelle Marchaux Fanny Langerwisch Andreas Huth Harald Bugmann Xavier Morin Christopher P.O. Reyer Rupert Seidl Alessio Collalti Mateus Dantas de Paula Rico Fischer Martin Gutsch Manfred J. Lexer Heike Lischke Anja Rammig Edna Rdig Boris Sakschewski Franziska Taubert Kirsten Thonicke Giorgio Vacchiano Friedrich J. Bohn 《Ecology and evolution》2021,11(9):3746
- Understanding the processes that shape forest functioning, structure, and diversity remains challenging, although data on forest systems are being collected at a rapid pace and across scales. Forest models have a long history in bridging data with ecological knowledge and can simulate forest dynamics over spatio‐temporal scales unreachable by most empirical investigations.
- We describe the development that different forest modelling communities have followed to underpin the leverage that simulation models offer for advancing our understanding of forest ecosystems.
- Using three widely applied but contrasting approaches – species distribution models, individual‐based forest models, and dynamic global vegetation models – as examples, we show how scientific and technical advances have led models to transgress their initial objectives and limitations. We provide an overview of recent model applications on current important ecological topics and pinpoint ten key questions that could, and should, be tackled with forest models in the next decade.
- Synthesis. This overview shows that forest models, due to their complementarity and mutual enrichment, represent an invaluable toolkit to address a wide range of fundamental and applied ecological questions, hence fostering a deeper understanding of forest dynamics in the context of global change.
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75.
Though the importance of membrane fluidity for cellular function has been well established for decades, methods for measuring lipid bilayer viscosity remain challenging to devise and implement. Recently, approaches based on characterizing the Brownian dynamics of individual tracers such as colloidal particles or lipid domains have provided insights into bilayer viscosity. For fluids in general, however, methods based on single-particle trajectories provide a limited view of hydrodynamic response. The technique of two-point microrheology, in which correlations between the Brownian dynamics of pairs of tracers report on the properties of the intervening medium, characterizes viscosity at length-scales that are larger than that of individual tracers and has less sensitivity to tracer-induced distortions, but has never been applied to lipid membranes. We present, to our knowledge, the first two-point microrheological study of lipid bilayers, examining the correlated motion of domains in phase-separated lipid vesicles and comparing one- and two-point results. We measure two-point correlation functions in excellent agreement with the forms predicted by two-dimensional hydrodynamic models, analysis of which reveals a viscosity intermediate between those of the two lipid phases, indicative of global fluid properties rather than the viscosity of the local neighborhood of the tracer. 相似文献
76.
In many plant and animal taxa mutation rates are higher in males than in females. As a result, the evolutionary speed of genes
depends on how much time they spend in either sex. Usually, this time differs between genes located on sex chromosomes but
not between those on autosomes. Here we present an unusual system with a partially sex-linked inheritance of autosomes: the
hemiclonal frog Rana esculenta (E) which is originally a hybrid between the sexual species R. lessonae (L) and R. ridibunda (R). Rana esculenta excludes the L genome prior to meiosis, produces eggs or sperm containing an unrecombined R genome and restores hybridity
by mating with R. lessonae (‘hybridogenesis’). Matings between L males and E females result in offspring with an even sex ratio, whereas the reverse
combination produces only daughters. The extent of the resulting female bias and the proportion that R alleles have spent
in either sex depend on the relative survival (b) and the relative reproductive contribution (a) of E males vs. E females. In this paper, we analyze mathematically how different combinations of a and b influence the sex ratio in R. esculenta populations and, combined with the male/female mutation rate ratio (α), the evolutionary rate of the clonally transmitted
R genome. We find that this rate is higher than in an asexual population and lower than in a sexual one. Hence, clonal diversity
through new mutations is more easily achievable than in purely asexual species. In contrast, the occurrence and accumulation
of deleterious mutations is lower than in a comparable sexual species. We conclude that these intermediate mutation rates
improve the ecological and evolutionary potential of hemiclonal organisms, and we draw attention to the implications for the
use of microsatellites.
Co-ordinating editor: L. Hurst 相似文献
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R W Reyer 《The American journal of anatomy》1990,188(4):345-365
The lens was removed from both eyes of adult newts (Notophthalmus viridescens), and the eyes were fixed in Karnovsky's fixative every 2 days 0-20 days after operation. Anterior half-eyes were prepared by standard procedures for scanning electron microscopy of the surface. Before fixation, the posterior iris surface was cleaned of adhering vitreous mechanically with forceps or by treatment with bovine testicular hyaluronidase or with hyaluronidase and collagenase. Some specimens were cryofractured in buffer or ethanol transverse to the mid-dorsal iris, and the fractured surface viewed with scanning electron microscopy (SEM). Cells with various combinations of ridges, blebs, filopodia, and lamellipodia were observed adhering to the posterior surface of the iris by 6 days after lentectomy. These cells, which exhibited the surface characteristics of macrophages, became more numerous in specimens fixed after longer intervals. Invasion of the iris epithelium was observed in a cryofractured specimen. After observations with SEM, selected specimens were embedded in plastic and sectioned for study with transmission electron microscopy (TEM). The cells on the iris surface had the cytological characteristics of macrophages, and other macrophages were located within the iris epithelium. In specimens fixed 16 or more days after lentectomy, a bulging lens vesicle was regenerating from the dorsal pupillary margin of the iris. Macrophages were absent or few on the surface of this developing lens but remained scattered over the adjoining iris. Roles that might be played by these macrophages during the transdifferentiation of iris epithelium into lens are discussed. 相似文献