Histone synthesis during early embryogenesis in Xenopus laevis (South African clawed toad)

Biochemistry ◽  
1973 ◽  
Vol 12 (2) ◽  
pp. 246-253 ◽  
Author(s):  
E. William Byrd ◽  
Harold E. Kasinsky
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Early Embryogenesis ◽  
Histone Synthesis

COMPARATIVE EFFECTS OF THE OESTROGENS AND OTHER STEROID HORMONES ON SERUM LIPIDS AND PROTEINS IN XENOPUS LAEVIS DAUDIN

1969 ◽  
Vol 43 (1) ◽  
pp. 47-53 ◽  
Author(s):  
M. R. REDSHAW ◽  
B. K. FOLLETT ◽  
T. J. NICHOLLS
Keyword(s):  
Plasma Concentration ◽  
Xenopus Laevis ◽  
Steroid Hormones ◽  
South African ◽  
Calcium Binding ◽  
Serum Lipids ◽  
Response Curves ◽  
Yolk Formation ◽  
Log Linear ◽  
Relative Potencies

SUMMARY A comparison has been made between the effects of oestradiol-17β, oestrone, oestriol, progesterone, testosterone and cortisone on the plasma concentration of proteins and lipids in the South African clawed toad, Xenopus laevis Daudin. No major changes in the parameters studied were found with the non-oestrogenic steroids; only the three oestrogens induced the appearance in the plasma of a calcium-binding phospholipoprotein and esterified lipids associated with yolk formation. These results support the hypothesis that the oestrogens alone cause the vitellogenic response in oviparous vertebrates. Dose—response curves for oestradiol-17β, oestrone and oestriol were established for the effects on plasma protein, calcium, protein-bound phosphorus, phospholipid, lipid and cholesterol. The curves obtained were log.-linear over the range of doses employed (oestradiol-17β, 1–50 μg./day; oestrone, 4–100 μg./day; oestriol, 20–500 μg./day) with the exception of the cholesterol response to oestradiol. The relative potencies of the three oestrogens were compared for each of the plasma components measured. Oestradiol-17β was the most potent, being 3·9 times more active than oestrone and 13·7 times more active than oestriol.

TISSUE DISTRIBUTION OF IMMUNOREACTIVE SOMATOSTATIN IN THE SOUTH AFRICAN CLAWED TOAD (XENOPUS LAEVIS)

1979 ◽  
Vol 80 (3) ◽  
pp. 407-408 ◽  
Author(s):  
B. SHAPIRO ◽  
M. SHEPPARD ◽  
S. KRONHEIM ◽  
B. L. PIMSTONE
Keyword(s):  
Xenopus Laevis ◽  
Tissue Distribution ◽  
South African ◽  
Rich Source ◽  
Gut Peptides ◽  
The South ◽  
The Brain

Immunoreactive somatostatin is present in the brain, gut and pancreas of the South African clawed toad, but is absent from the skin, a rich source of many other brain–gut peptides.

scholarly journals Developmental changes in oxygen consumption regulation in larvae of the South African clawed frog Xenopus laevis

1995 ◽  
Vol 198 (12) ◽  
pp. 2465-2475 ◽  
Author(s):  
D Hastings ◽  
W Burggren
Keyword(s):  
Oxygen Consumption ◽  
Lactic Acid ◽  
Xenopus Laevis ◽  
South African ◽  
Acute Hypoxia ◽  
Lactate Concentration ◽  
Aerobic Metabolism ◽  
Whole Body ◽  
Lactate Levels ◽  
Clawed Frog

Well-developed larval Xenopus laevis (NF stages 58­66) are oxygen regulators, at least during mild hypoxia. When and how they change from oxygen conformers (the presumed condition of the fertilized egg) to oxygen regulators is unknown. Also unknown is how anaerobic metabolic capabilities change during development, especially in response to acute hypoxia, and to what extent, if any, anaerobiosis is used to supplement aerobic metabolism. Consequently, we have investigated resting rates of oxygen consumption (M.O2) and concentrations of whole-body lactate (lactic acid) during development in normoxia and in response to acute hypoxia in Xenopus laevis. M.O2 increased in an episodic, non-linear fashion during development. Resting, normoxic M.O2 increased about tenfold (to approximately 0.20 µmol g-1 h-1) between NF stages 1­39 and 40­44, and then another tenfold between NF stages 45­48 and 49­51 (to approximately 2.0 µmol g-1 h-1), remaining at about 2 µmol g-1 h-1 for the remainder of larval development. M.O2 reached its highest level in newly metamorphosed frogs (nearly 4 µmol g-1 h-1), before decreasing to about 1.0 µmol g-1 h-1 in large adults. X. laevis embryos and larvae up to NF stage 54­57 were oxygen conformers when exposed to variable levels of acute hypoxia. The only exception was NF stage 45­48 (external gills present yet body mass still very small), which showed some capability of oxygen regulation. All larvae older than stage 54­57 and adults were oxygen regulators and had the lowest values of Pcrit (the oxygen partial pressure at which M.O2 begins to decline). Whole-body lactate concentration in normoxia was about 1 µmol g-1 for all larval groups, rising to about 12 µmol g-1 in adults. Concentrations of lactic acid in NF stages 1­51 were unaffected by even severe ambient hypoxia. However, whole-body lactate levels in NF stages 52­66 increased in response to severe hypoxia, indicating that some anaerobic metabolism was being used to supplement diminishing aerobic metabolism. The largest increases in concentration of lactate occurred in late larvae and adults.

Gene expression in Xenopus embryogenesis

Development ◽  
1985 ◽  
Vol 89 (Supplement) ◽  
pp. 113-124
Author(s):  
Igor B. Dawid ◽  
Susan R. Haynes ◽  
Milan Jamrich ◽  
Erzsebet Jonas ◽  
Seiji Miyatani ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Xenopus Laevis ◽  
Cdna Cloning ◽  
Early Embryogenesis ◽  
Gene Activity ◽  
Complex Nature ◽  
Cdna Clones ◽  
Midblastula Transition ◽  
First Time

This article considers some aspects of the storage of macromolecules in the oocyte of Xenopus laevis and the activation of previously unexpressed genes during early embryogenesis. The large quantity and complex nature of poly(A)+ RNA accumulated in the egg provides the cleavage embryo with a supply of mRNA sufficient to sustain protein synthesis for several hours of development. Onset of gene activity at the midblastula transition (MBT) leads to the synthesis and accumulation of molecules of various RNA classes, including tRNAs, rRNAs, mRNAs and mitochondrial RNAs. At gastrulation the poly(A)+ RNA population is still qualitatively similar to that of the egg but some sequences not present in egg RNA have accumulated by this time. Through the use of a subtractive cDNA cloning procedure we have prepared a library of sequences that represent genes activated for the first time between MBT and gastrula. A study of several of these cDNA clones suggests that genes in this class are restricted in their activity to embryonic and tadpole stages.

Retinal growth in double dorsal and double ventral eyes in Xenopus

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 175-185
Author(s):  
K. Straznicky ◽  
D. Tay
Keyword(s):  
Xenopus Laevis ◽  
Compound Eye ◽  
Ganglion Cells ◽  
Cell Number ◽  
Early Embryogenesis ◽  
Time Points ◽  
Retinal Growth

The growth of normal and surgically produced compound dorsal and ventral retinae in Xenopus laevis has been studied autoradiographically following injections of [3H]thymidine at stages 50 and 58. The animals were sacrificed 3 weeks after metamorphosis. The histogenetic pattern of the dorsal and ventral retinal halves was different at the three time points investigated, i.e. up to stage 50, between stages 50 and 58 and between stage 58 and 3 weeks after metamorphosis. Asymmetrical dorsal retinal growth occurred up to stage 50. From stage 50 onwards the retinal growth tendency reversed so that more ganglion cells were produced along the ventral than the dorsal ciliary margins. The overall preponderance of ventral retinal growth was 32·4% in cell number and 12·4% in retinal length from early embryogenesis to 3 weeks after metamorphosis. The characteristic histogenetic pattern of the dorsal and ventral retinal halves was maintained in an ectopic position in the compound eye, indicating that this particular property of the retinal halves is intrinsically determined.

The Adrenal Secretion of Xenopus Laevis (The South African Clawed Toad)

1932 ◽  
Vol 9 (3) ◽  
pp. 233-237
Author(s):  
D. EPSTEIN ◽  
J.W. C. GUNN ◽  
E. EPSTEIN ◽  
G. RIMER
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Normal Saline ◽  
Saline Solution ◽  
Ventral Surface ◽  
The South ◽  
Mammalian Tissues ◽  
Adrenal Secretion

1. Adrenal bodies have been shown to be present on the anterior or ventral surface of the kidneys of Xenopus. Extracts of this region of the kidney contain a sympathomimetic substance, probably adrenaline. 2. Active preparations are best obtained by extracting freshly excised kidneys with normal saline solution. The extracts should be used immediately. 3. Amphibian tissues appear to react more sensitively than mammalian tissues towards the extracts.

Histogenesis of lymphoid organs in larvae of the South African clawed toad, Xenopus laevis (Daudin)

Development ◽  
1969 ◽  
Vol 22 (2) ◽  
pp. 265-277
Author(s):  
Margaret J. Manning ◽  
John D. Horton
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Lymphoid Tissue ◽  
Rana Catesbeiana ◽  
Neck Region ◽  
Lymphoid Organs ◽  
The Body ◽  
Lymph Glands ◽  
Branchial Region ◽  
Myeloid Tissue

Before embarking on a study of the lymphoid system of an amphibian larva, it is necessary to realize that lymphoid tissue may occur in many organs of the body and that in all immature vertebrates and in adult poikilotherms separation of lymphoid tissue from myeloid tissue is incomplete (Yoffey, 1960). Jordan (1938) reviewed the early work on the haemopoietic tissues of Amphibia. Cooper (1967 a, b) and Baculi & Cooper (1967) made a thorough investigation of the lymphomyeloid and lymphoepithelial organs of the bullfrog, Rana catesbeiana, in the branchial region of the larva and in the ventral neck region of the adult. In the larva they found three pairs of ventral cavity bodies and one pair of lymph glands; in the adult, propericardial bodies, procoracoid bodies, epithelial bodies and jugular bodies were present. Cooper (1967a) reviewed the literature on these organs and discussed their nomenclature.

Sign in / Sign up

Export Citation Format

Share Document