Observations on the migration and proliferation of gonocytes in Xenopus laevis

Development ◽  
1976 ◽  
Vol 36 (1) ◽  
pp. 197-207
Author(s):  
Michiko Kamimura ◽  
Kohji Ikenishi ◽  
Minoru Kotani ◽  
Toru Matsuno
Keyword(s):  
Xenopus Laevis ◽  
Developmental Stages ◽  
Primordial Germ Cell ◽  
Cell Mass ◽  
Cell Formation ◽  
Initial Step ◽  
Peripheral Region ◽  
Genital Ridge ◽  
Tail Bud ◽  
Dorsal Mesentery

The process of primordial germ cell formation in the normal course of development of Xenopus laevis was examined with a light microscope on paraffin and Epon sections of embryos or tadpoles, extending over the period from the gastrula to the feeding tadpole stage. Positional changes of gonocytes with development were nearly the same as those reported on the same species by Bladder (1958) and Whitington & Dixon (1975). The following points were newly demonstrated. Gonocytes which have been located in a deep endodermal position till mid tail-bud stage come to be located in a rather peripheral region of the endoderm cell mass at stage 31 (late tail-bud), suggesting that the initial step of migration of the gonocytes towards the future genital ridge has already begun at this stage. Gonocytes at stages 33/34 and 35/36 were observed in a more dorsal part of the endoderm than at stage 31. Gonocytes which seem to have begun their migration are roundish in external shape and have a large intercellular space around them. At stage 40 gonocytes were located in the dorsal endodermal crest, and at stage 41 gonocytes were found with cell bodies extending over both the dorsal endoderm crest and the dorsal mesentery, indicating that the separation of the gonocytes from the endoderm was in progress at this stage. The present results seem to indicate that gonocytes migrate not passively but actively from the deep endodermal position to the genital ridge, passing through the dorsal mesentery. Counting the number of gonocytes at successive stages of development revealed that gonocytes proliferated exponentially throughout the developmental stages from gastrula to tadpole.

Stage-sensitivity and dose—response curve of u.v. effect on germ cell formation in embryos of Xenopus laevis

Development ◽  
1976 ◽  
Vol 35 (3) ◽  
pp. 617-623
Author(s):  
Ken-Ichi Ijiri
Keyword(s):  
Xenopus Laevis ◽  
Germ Cell ◽  
Dose Response ◽  
Response Curve ◽  
Developmental Stages ◽  
Primordial Germ Cells ◽  
Cell Formation ◽  
Dose Response Curve ◽  
Quantitative Studies ◽  
Germ Cell Formation

Ultraviolet light (u.v.) irradiation of the vegetal hemisphere of Xenopus laevis eggs resulted in the elimination of primordial germ cells in tadpoles. Quantitative studies were performed on this phenomenon. The stage sensitivity to u.v. in activation of germ cell formation was obtained for the early developmental stages ranging from immediately after fertilization to small cell blastula. It was found that u.v. irradiation at the stage immediately after fertilization was more injurious than irradiation at the beginning of the first cleavage. After deciding optimal conditions for this u.v. irradiation experiment, a dose-response curve of the phenomenon was obtained. It showed a good agreement with the theoretical expectation, which the authors had previously presented.

scholarly journals Integrated transcriptomic and proteomic analysis reveals the complex molecular mechanisms underlying stone cell formation in Korla pear

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aisajan Mamat ◽  
Kuerban Tusong ◽  
Juan Xu ◽  
Peng Yan ◽  
Chuang Mei ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Proteomic Analysis ◽  
Molecular Mechanisms ◽  
Developmental Stages ◽  
Cell Formation ◽  
Parenchyma Cell ◽  
Lignin Biosynthesis ◽  
Cell Content ◽  
Stone Cell ◽  
Fruit Samples

AbstractKorla pear (Pyrus sinkiangensis Yü) is a landrace selected from a hybrid pear species in the Xinjiang Autonomous Region in China. In recent years, pericarp roughening has been one of the major factors that adversely affects fruit quality. Compared with regular fruits, rough-skin fruits have a greater stone cell content. Stone cells compose sclerenchyma tissue that is formed by secondary thickening of parenchyma cell walls. In this work, we determined the main components of stone cells by isolating them from the pulp of rough-skin fruits at the ripening stage. Stone cell staining and apoptosis detection were then performed on fruit samples that were collected at three different developmental stages (20, 50 and 80 days after flowering (DAF)) representing the prime, late and stationary stages of stone cell differentiation, respectively. The same batches of samples were used for parallel transcriptomic and proteomic analysis to identify candidate genes and proteins that are related to SCW biogenesis in Korla pear fruits. The results showed that stone cells are mainly composed of cellulose (52%), hemicellulose (23%), lignin (20%) and a small amount of polysaccharides (3%). The periods of stone cell differentiation and cell apoptosis were synchronous and primarily occurred from 0 to 50 DAF. The stone cell components increased abundantly at 20 DAF but then decreased gradually. A total of 24,268 differentially expressed genes (DEGs) and 1011 differentially accumulated proteins (DAPs) were identified from the transcriptomic and proteomic data, respectively. We screened the DEGs and DAPs that were enriched in SCW-related pathways, including those associated with lignin biosynthesis (94 DEGs and 31 DAPs), cellulose and xylan biosynthesis (46 DEGs and 18 DAPs), S-adenosylmethionine (SAM) metabolic processes (10 DEGs and 3 DAPs), apoplastic ROS production (16 DEGs and 2 DAPs), and cell death (14 DEGs and 6 DAPs). Among the identified DEGs and DAPs, 63 significantly changed at both the transcript and protein levels during the experimental periods. In addition, the majority of these identified genes and proteins were expressed the most at the prime stage of stone cell differentiation, but their levels gradually decreased at the later stages.

scholarly journals NF-κB activity during pancreas development regulates adult β-cell mass by modulating neonatal β-cell proliferation and apoptosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dror Sever ◽  
Anat Hershko-Moshe ◽  
Rohit Srivastava ◽  
Roy Eldor ◽  
Daniel Hibsher ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Developmental Stages ◽  
Cell Mass ◽  
Diabetes Incidence ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Regulatory Circuit ◽  
Proliferation And Apoptosis

AbstractNF-κB is a well-characterized transcription factor, widely known for its roles in inflammation and immune responses, as well as in control of cell division and apoptosis. However, its function in β-cells is still being debated, as it appears to depend on the timing and kinetics of its activation. To elucidate the temporal role of NF-κB in vivo, we have generated two transgenic mouse models, the ToIβ and NOD/ToIβ mice, in which NF-κB activation is specifically and conditionally inhibited in β-cells. In this study, we present a novel function of the canonical NF-κB pathway during murine islet β-cell development. Interestingly, inhibiting the NF-κB pathway in β-cells during embryogenesis, but not after birth, in both ToIβ and NOD/ToIβ mice, increased β-cell turnover, ultimately resulting in a reduced β-cell mass. On the NOD background, this was associated with a marked increase in insulitis and diabetes incidence. While a robust nuclear immunoreactivity of the NF-κB p65-subunit was found in neonatal β-cells, significant activation was not detected in β-cells of either adult NOD/ToIβ mice or in the pancreata of recently diagnosed adult T1D patients. Moreover, in NOD/ToIβ mice, inhibiting NF-κB post-weaning had no effect on the development of diabetes or β-cell dysfunction. In conclusion, our data point to NF-κB as an important component of the physiological regulatory circuit that controls the balance of β-cell proliferation and apoptosis in the early developmental stages of insulin-producing cells, thus modulating β-cell mass and the development of diabetes in the mouse model of T1D.

Developmental stages, incubation temperature, and in vivo traceability of primordial germ cell in an important aquaculture species Piaractus mesopotamicus

Aquaculture ◽  
2021 ◽  
Vol 535 ◽  
pp. 736381
Author(s):  
Geovanna Carla Zacheo Coelho ◽  
Dilberto Ribeiro Arashiro ◽  
Tamiris Disselli ◽  
Matheus Pereira-Santos ◽  
Tatiana María Mira-López ◽  
...  
Keyword(s):  
Germ Cell ◽  
Developmental Stages ◽  
Incubation Temperature ◽  
Primordial Germ Cell ◽  
Piaractus Mesopotamicus

scholarly journals Epigenetic transgenerational inheritance, Gametogenesis and Germline Development

2021 ◽  
Author(s):  
Millissia Ben Maamar ◽  
Eric E Nilsson ◽  
Michael K Skinner
Keyword(s):  
Developmental Biology ◽  
Environmental Factors ◽  
Biological System ◽  
Developmental Stages ◽  
Primordial Germ Cell ◽  
Cell Types ◽  
Transgenerational Inheritance ◽  
Germline Development ◽  
Current Review

Abstract One of the most important developing cell types in any biological system is the gamete (sperm and egg). The transmission of phenotypes and optimally adapted physiology to subsequent generations is in large part controlled by gametogenesis. In contrast to genetics, the environment actively regulates epigenetics to impact the physiology and phenotype of cellular and biological systems. The integration of epigenetics and genetics is critical for all developmental biology systems at the cellular and organism level. The current review is focused on the role of epigenetics during gametogenesis for both the spermatogenesis system in the male and oogenesis system in the female. The developmental stages from the initial primordial germ cell through gametogenesis to the mature sperm and egg are presented. How environmental factors can influence the epigenetics of gametogenesis to impact the epigenetic transgenerational inheritance of phenotypic and physiological change in subsequent generations is reviewed.

scholarly journals ELECTRON MICROSCOPIC EXAMINATION OF THE SITES OF NUCLEAR RNA SYNTHESIS DURING AMPHIBIAN EMBRYOGENESIS

1965 ◽  
Vol 26 (3) ◽  
pp. 937-958 ◽  
Author(s):  
Shuichi Karasaki
Keyword(s):  
Rna Synthesis ◽  
Developmental Stages ◽  
Early Embryo ◽  
Tail Bud ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Nuclear Rna Synthesis ◽  
Nuclear Rna ◽  
Chromatin Material ◽  
Labeled Rna

The site of H3-uridine incorporation and the fate of labeled RNA during early embryo-genesis of the newt Triturus pyrrhogaster were studied with electron microscopic autoradiography. Isolated ectodermal and mesodermal tissues from the embryos were treated in H3-uridine for 3 hours and cultured in cold solution for various periods before fixation with OsO4 and embedding in Epon. At the blastula stage, the only structural component of the nucleus seen in electron micrographs is a mass of chromatin fibrils. At the early gastrula stage, the primary nucleoli originate as small dense fibrous bodies within the chromatin material. These dense fibrous nucleoli enlarge during successive developmental stages by the acquisition of granular components 150 A in diameter, which form a layer around them. Simultaneously larger granules (300 to 500 A) appear in the chromatin, and they fill the interchromatin spaces by the tail bud stage. Autoradiographic examination has demonstrated that nuclear RNA synthesis takes place in both the nucleolus and the chromatin, with the former consistently showing more label per unit area than the latter. When changes in the distribution pattern of radioactivity were studied 3 to 24 hours after immersion in isotope at each developmental stage, the following results were obtained. Labeled RNA is first localized in the fibrous region of the nucleolus and in the peripheral region of chromatin material. After longer culture in non-radioactive medium, labeled materials also appear in the granular region of the nucleolus and in the interchromatin areas. Further incubation gives labeling in cytoplasm.

Recherches sur le rôle de la température dans la réalisation du phénotype chez des embryons de l'Amphibien Pleurodeles waltlii homozygotes pour la mutation thermosensible ac (ascite caudale)

Development ◽  
1975 ◽  
Vol 34 (1) ◽  
pp. 221-252
Author(s):  
Par Maria Fernandez ◽  
Jean-Claude Beetschen
Keyword(s):  
Embryonic Development ◽  
Developmental Stages ◽  
Fluid Collection ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Tail Bud ◽  
Dorsal Fin ◽  
Second Shift ◽  
Pleurodeles Waltlii

1. At the feeding stage (st. 38), a high percentage (79 %) of Pleurodeles homozygous ac/ac larvae show bent tails after a persistent ascitic blister in the dorsal part of the fin, when embryonic development occurred at 12°C; about only 25 % of them are affected by abdominal and pericardic ascites; about 40 % can feed and survive. The larval phenotype is very different when embryonic development occurred at 23 °C, in which case tail growth appears to be normal, but 95 % larvae die, due to ascitic fluid collection in the abdominal and heart regions, marked anaemia and microcephaly. 2. The exchange of posterior neural plates and dorso-lateral epidermis between normal and mutant neurulae has shown that the localization of the blister in the dorsal fin is not dependent on autonomous properties of the mutant dorsal tissues, but should be considered as resulting from general disturbances in the mutant organism. 3. Experiments were performed, involving a temperature shift from 12 to 23°C or 23 to 12°C, occurring at various developmental stages from the end of gastrulation (stage 13) to the stage of spontaneous embryonic muscle contractions (stage 26). When the temperature shift was applied after the end of neurulation (stage 21), the caudal phenotype was statistically similar to that of larvae which had been bred continuously at the first temperature. Thus temperature-sensitive phases can be characterized between neurula stages 15 and 18 (for a 12–23° shift) or 15 and 21 (for a 23–12° shift). Similarly, abdominal ascites can be induced when embryos are kept at 23 °C till stage 23 (early tail-bud) only, and occurs much less frequently when embryos are kept at 12°C till stage 23 and then transferred to 23°C. 4. It could be concluded from these experiments that the caudal mutant phenotype is already temperature-determined during neurulation, before stage 21. Nevertheless, double temperature-shift experiments showed that the second shift could modify the results which would be obtained if the first shift only occurred. Paradoxical results were obtained, more than 90 % of the tail phenotypes being of the ‘warm type’ when the embryos were first kept at 12°C, then shifted up to 23 °C between stages 22 and 26, and shifted down again to 12°C. Such a treatment markedly lowers the percentage of bent tails (‘cold type’) from the percentage which would occur if ac/ac embryos were constantly kept at 23 °C after stage 21, but this longer warm treatment is of no effect of itself as compared to the case when the whole development occurs at 12°C (bent tails are predominant in this latter case). Thus, whereas the early determination of the position of the caudal blister can be considered as a stable phenomenon under given temperature conditions, it is not irreversible. 5. As compared to cold-bred larvae, thrice as many completely anaemic larvae (66 %) were obtained from ac/ac embryos kept at 23 °C between stages 21 and 26; this offers an opportunity for the experimental study of this anaemia. 6. Implications of these results for further analysis of temperature-sensitive mutations in cold-blooded vertebrates are suggested.

scholarly journals Evaluation of Effective and Practical Euthanasia Methods for Larval African Clawed Frogs (Xenopus laevis)

2020 ◽  
Vol 59 (3) ◽  
pp. 269-274
Author(s):  
Ilana A Galex ◽  
Cameron M Gallant ◽  
Nicole D'Avignon ◽  
Lauren M Kuchenbrod ◽  
Craig A Fletcher ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Developmental Stages ◽  
Age Group ◽  
Research Model ◽  
Larval Stages ◽  
Large Numbers ◽  
Guidance Documents ◽  
Stock Solutions ◽  
Tricaine Methanesulfonate ◽  
Tank Water

Larval, or tadpole-stage Xenopus laevis frogs are a popular research model for developmental biology and disease studies. Existing euthanasia guidance documents offer recommendations for both eggs and adult stages, yet do not specifically address the larval stage. Data evaluating effective euthanasia methods for groups of X. laevis tadpoles would therefore be useful. The goal of the current study was to evaluate the efficacy of various immersion euthanasia procedures on tadpoles: tricaine methanesulfonate (MS222) at 6 g/L, eugenol at 800 μL/L and rapid chilling (2 to 4 °C). We also evaluated tadpoles at various developmental stages (NF stages 46, 47 and 49). Tadpoles (n = 70) were exposed to euthanasia solution for 15 min, and controls (n = 40) were placed in housing tank water for 15 min. All animals were then placed in recovery tanks containing housing tank water for 4 h to confirm irreversibility of each agent. Cessation of the heartbeat was assessed at the end of euthanasia solution exposure and at each hour thereafter. We found that immersion in a 6 g/L solution of MS222 resulted in 100% euthanasia of all larval stages tested. Conversely, eugenol produced variable euthanasia rates that were affected by both age group and batches of stock solutions. Rapid chilling was completely ineffective as a euthanasia method in our study. Based on our findings, we recommend MS222 as an effective and practical means of euthanizing large numbers of X. laevis tadpoles.

scholarly journals In vitro Embryo Morphogenesis and Micropropagation of Dendrobium aggregatum Roxb.

2014 ◽  
Vol 23 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Mohammad Musharof Hossain
Keyword(s):  
Seed Germination ◽  
Plant Growth ◽  
Developmental Stages ◽  
Cell Mass ◽  
Multiple Shoot ◽  
Seedling Development ◽  
Ms Medium ◽  
Multiple Shoot Buds ◽  
Half Strength

In vitro embryo morphogenesis and micropropagation of Dendrobium aggregatum Roxb. were described. The gradual developmental stages of embryos to seedlings were traced out. Within two weeks of culture the cells of undifferented embryos underwent repeated aniclinal and periclinal division producing a compact, green parenchymatous cell mass called spherule that emerged out by rupturing the testa. The spherules subsequently differentiated into greenish protocorms were considered as typical seed germination. Germination occurred on both (MS and Phytamax (PM) medium but MS medium proved to be more efficient. The primary protocorms underwent profuse proliferation through production of secondary (2º) protocorms when transferred to different plant growth regulators (PGRs) supplemented MS; the medium fortified with 2.0 mg/l BAP and 1.0 mg/l NAA proved to be most effective for induction of 2º protocorms and seedling development. Multiple shoot buds (MSBs) were induced in pseudobulb segments of the in vitro grown seedlings when cultured on different PGRs supplemented media; and the maximum number of MSBs were obtained MS + 2.0 mg/l BAP + 0.5 mg/l picloram. The MSBs underwent elongation and then they rooted when they were transferred to half strength of MS + 0.5 mg/l IAA. The well rooted plantlets were finally transferred to outside natural environment with 80% survival. D. O. I. http://dx.doi.org/10.3329/ptcb.v23i2.17525 Plant Tissue Cult. & Biotech. 23(2): 241-249, 2013  (December)

The role of water-regulating mechanisms in the development of the haploid syndrome in Xenopus laevis

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 449-462
Author(s):  
Louie Hamilton ◽  
P. H. Tuft
Keyword(s):  
Xenopus Laevis ◽  
Cell Number ◽  
Gastrula Stage ◽  
Tail Bud ◽  
Volume Changes ◽  
Membrane Area ◽  
Flow Through ◽  
The Difference ◽  
Haploid Embryos

The uptake of water by haploid and diploid sibling embryos of Xenopus laevis has been investigated by measuring the density changes which occur during the development of intact embryos from the blastula to the late tail-bud stage, and of explants from which most of the presumptive endoderm has been removed. The results show that up to the mid-gastrula stage there is no difference between the haploid and diploid embryos; but from then on, whereas the diploid volume increases steadily, the haploid gastrulae undergo a series of cyclical volume changes due to loss of fluid through the blastopore. It is concluded that this is the result of an excessive inflow of water through the haploid ectoderm, because it was found that the volume of haploid ectodermal explants increased much more rapidly than the volume of similar diploid explants. Excess flow through the haploid ectoderm also accounts for other characteristics of the haploid syndrome – microcephaly and lordosis. It is suggested that it is the doubling of the cell number in haploid embryos with the consequent 25% increase in aggregate cell membrane area which accounts for the difference between the uptake of water by the two types of embryos. It is also suggested that changes in the rate of water flow through the ectoderm and endoderm which are thought to account for the accumulation of water in the blastocoel and archenteron in the normal diploid embryo arise in a similar way.

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