共查询到20条相似文献,搜索用时 15 毫秒
1.
A. B. Burlakov O. V. Burlakova V. A. Golichenkov 《Russian Journal of Developmental Biology》2000,31(5):287-292
Groups of loach (Misgurnus fossilis L.) embryos of different ages were kept in different quartz cuvettes for 20–24 h so that only optic contact between the groups
was, possible. Subsequent observations showed that parameters of their development deviated from those in the control groups.
Wave-mediated biocorrection proved to have both positive and negative effects, depending on the developmental stages of the
interacting groups. Changes in spectral characteristics and polarization of biological radiation affected the results of the
experiments. Various developmental abnormalities, caused by distant wave-mediated interactions of embryos and specific to
each combination of developmental stages and conditions of optic communication are described. 相似文献
2.
P. E. Binkerd A. G. Hendrickx J. M. Rice A. E. Palmer 《American journal of primatology》1984,6(1):15-29
The developmental stages of 12 Erythrocebus patas embryos, ranging in gestational age from 30 to 50 days, is described. The pattern of embryogenesis in E. patas closely parallels the anatomic characteristics of human and other nonhuman primate embryos between stages 12 and 23. However, there is a delay in development in E. patas similar to that observed in human embryos which differs from the macaques and baboons. This temporal difference in the embryonic period is an important factor in the design and analysis of early pregnancy studies in this species. 相似文献
3.
Summary The influence of the zygotic seed coat on precocious germination and desiccation tolerance of somatic embryos has been studied using alfalfa (Medicago sativa L.). When cultured in contact with somatic embryos, seed coats at certain developmental stages inhibited precocious germination and induced desiccation tolerance in the somatic embryos. Germination of somatic embryos was inhibited by seed coats at the age of 16–26 days after pollination (DAP) and desiccation tolerance was induced after 20–26 DAP. Both phenomena were related to the synthesis of abscisic acid in the seed coat. The absence of a quiescent phase and desiccation tolerance in alfalfa somatic embryos may be related to the lack of developmental control by the seed coat.Abbreviations ABA
Abscisic acid
- DAP
Days after pollination 相似文献
4.
Scanning electron microscopy has been used to investigate the morphological changes occurring during the development of alfalfa somatic embryos. Embryos were initiated from callus, transferred to suspension culture and matured on solid agar medium. This developmental pattern was compared to that of zygotic embryos developing in ovulo. Somatic embryos begin as distinct pro-embryos within the callus tissue pieces placed in suspension culture. They become globular and heart-shaped while on solid agar medium and then undergo cotyledon elongation and maturation. Somatic embryos develop comparatively slower at early stages of development and faster at the later stages than zygotic embryos. They lack a well-defined suspensor and have a very rough, poorly-differentiated epidermis, the first layer of which is lost after pro-embryo formation. The cotyledons of somatic embryos are multiple and poorlydeveloped; there appears to be a correlation between the amount of surface roughness of the developing embryo and the extent to which polycotyledony occurs. 相似文献
5.
Summary Conditions for the isolation and purification of ribosome proteins from developing Xenopus embryos have been established. The procedure involves the preparation of ribosome gradients, and from the monosomes and polysomes their protein. These proteins are purified by an ammonium chloride wash and are separated by electrophoresis. Results indicate that differences do not exist between monosome ribosome proteins from different developmental stages, but do exist between these monosomes and ribosomal protein from postgastrula polysomes. The possible role of the ribosome in translation-level control is discussed. 相似文献
6.
《Genesis (New York, N.Y. : 2000)》2009,47(11):spcone-spcone
Opened brood chamber with embryos of different stages from the demosponge Amphimedon queenslandica. This poriferan species has its genome sequenced, assembled, and annotated and serves as a model organism for sponge developmental biology. Image supplied by Bernie Degnan (University of Queensland). 相似文献
7.
A L Allenspach 《Journal of morphology》1970,131(1):89-101
Retrogressive analysis of the cn gene effect has been performed on crooked neck dwarf chick embryos between stages 28–38 (5–12 days). The phenocritical stage of mutant embryos studied is stage 29. Histolytic degeneration of neck tissues is first recognized by the appearance of localized degenerate nuclei in the tracheal mesenchyme. Pleiotropic autolysis of the embryonic thymus, loose mesenchyme and the ventral neck tissue is also observed. Histolysis occurs in a caudocephalic gradient in all cn-affected embryos. The degenerative effects in crooked neck dwarf embryos vary in their intensity, but the pattern of autolysis seems constant. Histological observations provide some explanation for “escapers,” homozygous lethal embryos known to survive until hatching. A mechanism for surviving developmental crises in cn embryos is proposed. 相似文献
8.
Daniel Vestman Emma Larsson Daniel Uddenberg John Cairney David Clapham Eva Sundberg Sara von Arnold 《Tree Genetics & Genomes》2011,7(2):347-362
The aim of this study has been to identify important processes that regulate early stages of embryo development in conifers.
Somatic embryogenesis in Picea abies has become a model system for studying embryology in conifers, providing a well-characterized sequence of developmental stages,
resembling zygotic embryogeny, which can be synchronized by specific treatments, making it possible to collect a large number
of somatic embryos at specific developmental stages. We have used this model to analyze global changes in gene expression
during early stages of embryo development by generating an expression profile of 12,536 complementary DNA clones. This has
allowed us to identify molecular events regulating putative processes associated with pattern formation during the earliest
stages of embryogenesis which have not been identified on the molecular level in conifers before. We recognize notable changes
in the expression of genes involved in regulating auxin biosynthesis and auxin response, gibberellin-mediated signaling, signaling
between the embryo and the female gametophyte, tissue specification including the formation of boundary regions, and the switch
from embryonic to vegetative development. In addition, our results confirm the involvement of previously described processes,
including stress, differentiation of a protoderm, and programmed cell death. 相似文献
9.
Somatic embryogenesis and plantlet development in Pinus sylvestris and Pinus pinaster on medium with and without growth regulators 总被引:3,自引:0,他引:3
Marie-Anne Lelu Catherine Bastien Aurélie Drugeault Marie-Laure Gouez Krystyna Klimaszewska 《Physiologia plantarum》1999,105(4):719-728
To initiate somatic embryogenesis in Pinus sylvestris and Pinus pinaster, immature seeds were collected from June to August and the developmental stage of the zygotic embryos was determined. Four developmental stages were distinguished and the response of the zygotic embryos at each of the four developmental stages was compared intra- and inter-species. For this study, modified Litvay's medium (LM), with or without growth regulators, was chosen. Somatic embryogenesis was initiated and maintained on both media but the two species displayed different propensities. In P. sylvestris, the highest initiation frequency was obtained with intact megagametophytes containing embryos at the four-cell stage to the stage of cleavage polyembryony (up to 22 and 9%, respectively). The culture medium had no significant effect on the initiation and proliferation of embryogenic cultures. In P. pinaster, however, the best response occurred from excised zygotic embryos at the stage prior to elongation of cotyledon primordia (up to 40% explants responded), on medium with growth regulators. Another characteristic distinguishing the two species in culture was that in some embryogenic cell lines of P. sylvestris, somatic embryos matured spontaneously when initiated and maintained on medium without growth regulators. Some of these embryos developed into plantlets on the same medium at the frequency of 40%. Therefore, in P. sylvestris all the stages of somatic embryogenesis were achieved on the medium without growth regulators. However, in both species, maturation of a large number of somatic embryos was greatly improved on medium containing high concentration of gellan gum (Gelrite 10 g l?1) and abscisic acid (60 μM). Cotyledonary somatic embryos subsequently germinated (72 and 80% for P. sylvestris and P. pinaster, respectively) and developed into plantlets (48 and 29%, for P. sylvestris and P. pinaster, respectively). This represents a significant improvement in plantlet recovery from somatic embryos of both species. 相似文献
10.
Summary The effect of chloramphenicol (CP) on the development ofPlanorbis exustus has been studied. The antibiotic is found to inhibit cleavage at high concentrations. At low concentrations development is blocked at early gastrulation. There are indications that the effect cannot be reversed by mere transfer of the embryos into normal medium, if they have been treated for 48 hours. If transfer into normal medium is made 24 hours after commencement of treatment, development is resumed.Gastrulae developed normally even in the presence of CP. In low concentrations of CP a characteristic delay in development is observed between the trochophore and hippo stages.The significance of this developmental inhibition has been discussed in relation to synthetic processes occurring in the various phases of development.The antilytic property of CP is evident in these experiments. 相似文献
11.
S N Van Horn 《Journal of morphology》1966,120(1):83-114
The growth and morphogenesis of embryos of Aulocara elliotti (Thomas) at constant temperature are described in terms of 27 discrete morphological stages with four stages designating blastokinesis. The developmental variability of two series of embryos reared from a single wild population in two different years is compared. A bibliography to studies on other embryos of the Acrididae is included. 相似文献
12.
Kendal S. Broadie Michael Bate Nathan J. Tublitz 《Development genes and evolution》1991,199(6):327-334
Summary A complete timetable of embryonic development of the tobacco hawkmoth,Manduca sexta (Lepidoptera: Sphingidae), is presented. Using living embryos, 20 developmental stages from oviposition to hatching are described with respect to their morphological and physiological maturation. This staging series provides a simple method to identify the stage ofManduca development during all phases of embryogenesis. 相似文献
13.
Jan B. M. Custers Jan H. G. Cordewener Yvonne Nöllen Hans J. M. Dons Michiel M. Van Lockeren Campagne 《Plant cell reports》1994,13(5):267-271
Summary Temperature controls the developmental fate of isolated Brassica napus microspores in vitro. Culture at 32.5°C leads to sporophytic development and the formation of embryos. Here we show that culture at 17.5°C leads to gametophytic development, and the formation of pollen-like structures at high frequencies (up to 80% after 7 days in culture). Early stages of both developmental pathways are observed in culture at 25.0°C, and embryos are produced at low frequencies (0.7%) at that temperature. Culturing B. napus microspores at 32.5°C versus 17.5°C brings the switch from gametophytic to sporophytic development under simple experimental control and provides a convenient tool for investigating the cellular and molecular mechanisms controlling this developmental switch. 相似文献
14.
Rat embryos at a single gestational time in the presomite period were studied for their variation in development and their fate after culture. They were explanted at 8 A.M. on day 9 of gestation from timed-pregnant Sprague-Dawley rats which were obtained by mating between 8 and 10 A.M. (plug day = day 0). In the first experiment, a total of 203 embryos from 20 litters were examined for their variation in development. Several dimensions of embryo/egg cylinder were measured and development of various embryonic/extraembryonic structures were assessed using a scoring system that we developed for the present study. Embryos were then divided into different stages of development based on their scores using the staging system that we developed previously. A large variation in developmental stage was demonstrated; the youngest embryo was at the early primitive streak stage with no signs of amniotic folds and the oldest one was at the late neural plate stage with a foregut pocket but without visible somites. No strong correlation was demonstrated between developmental stage and size of embryo/egg cylinder, nor between developmental stage and development of the proamniotic tube, ectoplacental cavity, or allantois. In the second experiment, embryos were explanted at the same time and those at different stages were cultured separately in rotating bottles and their outcomes were compared after 49 hours. The difference in mean somites number of embryos cultured from the mid primitive streak and late neural plate stages was 6.1. This difference corresponds to approximately 10 hours based on the known linear increase of somites number on day 11 of approximately 0.6 somites per hour. These results indicate a large variation in development of presomite period embryos supposedly of the same gestational age and suggest the importance of careful staging at the time of explantation if precision is needed for whole embryo culture experiments. 相似文献
15.
The adverse effects of high temperatures on the early life stages of anadromous whitefish Coregonus lavaretus were experimentally examined by assessing fertilization success, the percentage of developmental abnormalities, cumulative mortality and the rate of embryogenesis across a range of temperatures. Temperatures ≥ 7° C increased the proportion of unfertilized and abnormally dividing eggs, deformed embryos and consequent mortality. The higher the temperature, the more severe were the effects. When eggs were fertilized and constantly incubated at various temperatures, the effective level for 50% of the eggs and embryos (EL50) of temperature was 7·6° C at the developmental stage when eye pigmentation was visible. Fewer developmental abnormalities and a lower cumulative mortality rate were observed when embryos were exposed to high temperatures from the later, gastrula stage, than from fertilization or the four‐cell stage. Irrespective of retarded development in terms of day‐degrees (i.e. the sum of daily mean temperatures), a high incubation temperature reduced the development time of C. lavaretus, leading to earlier hatching, and hatched fry were shorter than at the reference temperature of 4–5° C. Global warming will particularly pose risks for stenothermic species such as C. lavaretus, with early life stages being especially susceptible. Thus, relatively small increases and fluctuations in river water temperatures during the spawning season of this anadromous species may have substantial negative impacts on its recruitment and population persistence. 相似文献
16.
17.
Tom Kashiwagi Aaron J. DeLonay Patrick J. Braaten Kimberly A. Chojnacki Rachel M. Gocker Edward J. Heist 《Journal of fish biology》2020,96(2):486-495
We produced pallid sturgeon Scaphirhynchus albus embryos at five pre-hatch developmental stages and isolated and quantified genomic DNA from four of the stages using four commercial DNA isolation kits. Genomic DNA prepared using the kit that produced the largest yields and concentrations were used for microsatellite DNA analyses of 10–20 embryos at each of the five developmental stages. We attempted to genotype the hatchery-produced embryos at 19 microsatellite loci and confirmed reliable genotyping by comparing the microsatellite genotypes to those of known parents. Embryos at stages 5 and 8 did not produce reliable genotyping while those at stages 14, 24 and 33 did. We used the same DNA isolation method on 262 wild-caught acipenseriform embryos collected from the lower Yellowstone River. A total of 200 of the wild embryos were successfully identified to stages 8 to 34 and the rest could not be staged. Using a combination of single nucleotide polymorphism and microsatellite markers, 249 of the wild-caught embryos were genetically identified as paddlefish Polyodon spathula, five were identified as shovelnose sturgeon Scaphirhynchus platorynchus and eight failed to amplify. None were identified as pallid sturgeon. This study demonstrates that early-stage wild-spawned acipenseriform embryos can be genetically identified less than 24 h post-spawn. This methodology will be useful for recovery efforts for endangered pallid sturgeon and can be applied to other acipenseriform species. 相似文献
18.
Madhumita das Sarmistha Sen Raychaudhuri 《In vitro cellular & developmental biology. Plant》2001,37(5):568-571
Summary
Plantago ovata Forsk (commonly known as Isabgul) is an economically important medicinal plant. In the present investigation, in vitro plant regeneration of P. ovata was attempted through somatic embryogenesis. Casein hydrolysate and coconut water were used in different concentrations in
Murashige and Skoog medium along with 1-naphthaleneacetic acid and N6-benzyladenine to increase the amount of callus and number of somatic embryos. Light and scanning electron microscopic studies
followed the developmental stages of embryo formation. Results indicated that optimum concentrations of casein hydrolysate
and coconut water are useful for promoting the growth of embryogenic cultures. However, a supra-optimal dose of casein hydrolysate
and coconut water induced polyphenol synthesis and caused browning of callus and also eventual death of embryos. The use of
additives such as coconut water and casein hydrolysate promotes large-scale production of P. ovata through in vitro somatic embryogenesis. 相似文献
19.
20.
Synopsis Intraovarian development of embryos was observed in 31 female rockfish kurosoi,Sebastes schlegeli, which had been raised in the laboratory. Three of the females had newly fertilized eggs; the others' embryos were at various
stages. The developmental series (33 stages) was not very different from that in oviparous fishes. However, several characteristic
features were noted: thin egg envelope, narrow perivitelline space, elliptical encapsulated embryo in the late stages and
depletion of yolk at parturition. The time course of development up to birth at different temperatures was adjusted to that
at 9.8°C using the Arrhenius equation and processed for the relationship between the stage number (X) and stage-to-birth time
in days (Y). An equation,
was obtained, and the gestation period was calculated to be 48 days at 9.8°C. 相似文献