scholarly journals The Inorganic Constituents of the Sea-Urchin Egg

1953 ◽  
Vol 30 (4) ◽  
pp. 534-544
Author(s):  
LORD ROTHSCHILD ◽  
H. BARNES
Keyword(s):  
Sea Urchin ◽  
Total Phosphorus ◽  
Phosphorus Content ◽  
Sea Water ◽  
Paracentrotus Lividus ◽  
Dry Weight ◽  
Chemical Methods ◽  
Sea Urchin Egg ◽  
Soluble Phosphorus ◽  
Inorganic Constituents

1. The principal inorganic constituents of the unfertilized egg of Paracentrotus lividus have been analysed by chemical methods. The results of the analyses, in millimoles per kg. of water in the eggs (dry weight of eggs, 24%; density, 1.09), were: The figures in brackets are the concentrations of the same substances in Roscoff sea water, chlorinity 19.37‰ in the same units. 2. The total phosphorus content of the eggs was about 2 mg./ml. eggs, somewhat over half of this being acid-soluble phosphorus.

scholarly journals CHANGES IN THE POTASSIUM CONTENT OF SEA URCHIN EGGS ON FERTILIZATION

1951 ◽  
Vol 34 (3) ◽  
pp. 285-293 ◽  
Author(s):  
Anna Monroy Oddo ◽  
Maria Esposito
Keyword(s):  
Sea Urchin ◽  
Sea Water ◽  
Paracentrotus Lividus ◽  
Potassium Content ◽  
Minimum Point ◽  
Sea Urchin Eggs ◽  
Maximum Loss ◽  
Arbacia Lixula

In the eggs of Arbacia lixula and Paracentrotus lividus an uptake of K occurs during the first 10 minutes following fertilization. Between 10 and 40 minutes K is then released. Both in Arbacia and in Paracentrotus the minimum point of the curve coincides with the nuclear streak stage. A maximum loss of 25 per cent in Arbacia and 20 per cent in Paracentrotus with respect to the amount present in the unfertilized eggs has been found. From 40 minutes up to 1 hour K undergoes a further increase and when the first cleavage sets in the same amount of K is present as in the unfertilized eggs. By treating the eggs with K-free artificial sea water it has been established that about 60 per cent of the K content of the eggs is in a non-diffusible condition. Also under such conditions the eggs when fertilized are able to take up even the very small amount of K present in the medium that was released by them prior to fertilization.

scholarly journals THE MEMBRANE CAPACITANCE OF THE SEA URCHIN EGG

1957 ◽  
Vol 3 (1) ◽  
pp. 103-110 ◽  
Author(s):  
Lord Rothschild
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Sea Water ◽  
Unit Area ◽  
Membrane Capacitance ◽  
Percentage Reduction ◽  
Cortical Granules ◽  
Sea Urchin Egg

1. The surface of the unfertilized sea urchin egg is folded and the folds are reversibly eliminated by exposing the egg to hypotonic sea water. If the plasma membrane is outside the layer of cortical granules, unfolding may explain why the membrane capacitance per unit area decreases (and does not increase) when a sea urchin egg is put into hypotonic sea water. 2. The degree of surface folding markedly increases after fertilization, which provides an explanation for the increase in membrane capacitance per unit area observed after fertilization. 3. The percentage reduction in membrane folding in fertilized eggs after immersion in hypotonic sea water is probably sufficient to explain the decrease in membrane capacitance per unit area observed in these conditions.

The Physiology of Sea-Urchin Spermatozoa

1952 ◽  
Vol 29 (1) ◽  
pp. 66-71
Author(s):  
LORD ROTHSCHILD ◽  
K. W. CLELAND
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Sea Urchin ◽  
Sea Water ◽  
Dry Weight ◽  
Arithmetic Mean ◽  
Middle Piece ◽  
Oxidative Breakdown ◽  
Principal Source ◽  
Fresh Semen

1. Sea-urchin spermatozoa (Echinus esculentus) contain 4·14 mg. phospholipid per 1010 spermatozoa (arithmetic mean of five replicated experiments, standard error 0·06). This amount of phospholipid is about 5·5% of the dry weight of a sea-urchin spermatozoon. 2. The seminal plasma contains very small quantities of phospholipid, about 20 mg./100 ml., less than one-thirtieth the content of fresh semen. 3. When sea-urchin semen was diluted 1:20 with sea water and the spermatozoa incubated aerobically for some 7 hr.at 20°C., phospholipid disappeared. The average disappearance per 1010 spermatozoa was 19·0% (S.E. 2·4), while the corresponding oxygen uptake of the same sperm suspensions during the same time was 1·450 ml. (S.E. 0·118). The oxidation of glycogen or glycogen-like material was found to be entirely insufficient to account for the observed oxygen consumption. 4. Assuming that the combustion of 1 mg. phospholipid requires 1·6 ml. oxygen, the ratio of the theoretical oxygen uptake (associated with the observed disappearance of phospholipid) to the observed oxygen uptake was 0·86 (S.E. 0·04). 5. It is concluded that the oxidative breakdown of phospholipid, located in the middle-piece, is the principal source of the energy required for movement.

scholarly journals Microdissection Experiments on Sea-Urchin Eggs at Cleavage

1953 ◽  
Vol 30 (4) ◽  
pp. 515-524
Author(s):  
J. M. MITCHISON
Keyword(s):  
Internal Pressure ◽  
Sea Urchin ◽  
Sea Water ◽  
Sea Urchins ◽  
The Other ◽  
Membrane Tension ◽  
Membrane Theory ◽  
Sea Urchin Egg ◽  
Pass Through ◽  
Irreparable Damage

1. Chambers (1938) described an experiment in which he cut open one blasto-mere of a cleaving sea-urchin egg at the dumb-bell stage in isotonic KCl. The other blastomere contracted like a ‘deflating balloon’, and this has been taken by other workers as evidence of a positive membrane tension in the cleaving egg. This experiment has been repeated with other sea urchins in various media. It is concluded that this effect only takes place in one species of sea urchin, in an abnormal medium, and after it has suffered irreparable damage. It is not, therefore, legitimate to suppose that there is normally a positive membrane tension in a cleaving egg. It is found that eggs will continue to cleave with one blastomere in an irregular shape which indicates that, on the contrary, there is no membrane tension and no internal pressure. These are the conditions demanded by the ‘expanding membrane’ theory of cleavage. 2. It is found that the furrow of a cleaving egg will pass through a needle placed in its path. This result argues against a simple contracting ring in the furrow region being responsible for cleavage. 3. Chambers (1938) found that an egg will continue to cleave when its asters have been destroyed by stirring. This result has been confirmed by a similar experiment on a different species of sea urchin. This is crucial evidence against an astral mechanism of cleavage. 4. The effects of compressing cleaving eggs have been studied. It is found that compressed eggs continue to cleave unless the degree of flattening is considerable; that cleavage is delayed before it is finally stopped; and that eggs in Ca-free sea water are more susceptible to compression than eggs in ordinary sea water. These results are consistent with the ‘expanding membrane’ theory.

THE EVALUATION OF THE RESIDUAL EFFECT OF FERTILIZER IN LONG-TERM FERTILITY PLOTS: II. PHOSPHORUS

1964 ◽  
Vol 44 (2) ◽  
pp. 223-227 ◽  
Author(s):  
A. A. MacLean
Keyword(s):  
Sodium Bicarbonate ◽  
Total Phosphorus ◽  
Phosphorus Content ◽  
Surface Soil ◽  
Phosphorus Uptake ◽  
Residual Effect ◽  
Total Phosphorus Content ◽  
Soluble Phosphorus ◽  
The Relationship

Long-term annual applications of fertilizer phosphorus to an acid sandy loam podzol resulted in marked increases in total phosphorus content of the surface soil. However, downward movement was limited as no increase occurred below 9 in. The relationship between total phosphorus content of the profile and sodium bicarbonate-soluble phosphorus (r = 0.93) was significant at the 1% level. Phosphate retention capacity of the surface soil was not influenced by fertilizer or manurial treatment and increases in percentage phosphorus saturation were relatively small.Under conditions of intensive cropping in the greenhouse (12 crops), residual phosphorus was highly effective in supplying crop requirements. However, the results suggest that fertilizer phosphorus may be beneficial during the establishment period. The relationship between phosphorus uptake on the no P series in the greenhouse and levels of sodium bicarbonate-soluble phosphorus (r = 0.88) is further evidence of the value of this method in estimating phosphorus availability in soils.

scholarly journals ANTIGENS IN EGGS AND DEVELOPMENTAL STAGES OF THE SEA URCHIN

1964 ◽  
Vol 22 (2) ◽  
pp. 307-316 ◽  
Author(s):  
Peter Perlmann ◽  
Jane Couffer-Kaltenbach
Keyword(s):  
Sea Urchin ◽  
Developmental Stages ◽  
Sea Water ◽  
Paracentrotus Lividus ◽  
Protein Antigens ◽  
Preparative Scale ◽  
Low Speed ◽  
Diffusion Technique ◽  
Cell Fractions ◽  
Isolated Cell

Homogenates of fertilized eggs of the sea urchin Paracentrotus lividus were fractionated by differential centrifugation. In addition, whole eggs were fragmented, on a preparative scale, by centrifugation in sea water-sucrose gradients. The fractions and fragments were subsequently assayed for their content of soluble protein antigens described in an earlier publication. Relative concentrations of antigen present in quantitatively isolated cell fractions were estimated by graded antiserum absorption in combination with agar-diffusion technique. Two of six antigens were found to be associated mainly with the low speed sediments. Treatment of the various sediments with hypotonic medium and results obtained with fragmented eggs suggested that these two antigens and possibly a third were probably located in the yolk granules. The other antigens were more evenly distributed among the low speed sediments and the non-sedimented part of the cytoplasm. Only one of the antigens was consistently associated with the microsomal fraction.

Further studies of the effects of deprivation of sulfate on the early development of the sea urchin Paracentrotus lividus

Development ◽  
1965 ◽  
Vol 14 (3) ◽  
pp. 289-305
Author(s):  
J. Immers ◽  
J. Runnström
Keyword(s):  
Sea Urchin ◽  
Developmental Stages ◽  
Sea Water ◽  
Sea Urchins ◽  
Paracentrotus Lividus ◽  
The Other ◽  
Free Medium ◽  
Dominant Group ◽  
And Function ◽  
Early Developmental

The morphological effects of sulfate-free medium on sea urchin embryos were described in detail by Herbst (1904). Further studies were carried out by Lindahl (1936, 1942). He was the first to consider metabolic aspects of the rôle of sulfate in the development of the sea urchin. Immers (1956, 1959, 1961a and b, 1962) studied the distribution and function of acid mucopolysaccharides in early developmental stages of sea urchins, mainly Paracentrotus lividus. A dominant group of these acid polysaccharides are sulfated. Their location in the blastocoel, in the hyaline layer and in the lumen of the intestine could be demonstrated by staining of sectioned specimens with the ferri-acetic reagent of Hale (1946). In blastulae or gastrulae raised in sulfate-free sea water these regions are negative with respect to Hale staining (Immers, 1961b). On the other hand, the ectodermal nuclei of the animal region of the embryos are stained with the Hale reagent although the nuclei of the vegetal region remained unstained (1.c.).

The Metabolism of the Sea-Urchin Egg

1952 ◽  
Vol 29 (2) ◽  
pp. 285-294
Author(s):  
K. W. CLELAND ◽  
LORD ROTHSCHILD
Keyword(s):  
Lactic Acid ◽  
Sea Urchin ◽  
Lactic Acid Production ◽  
Dry Weight ◽  
Glycolytic Enzyme ◽  
Anaerobic Conditions ◽  
Sea Urchin Egg ◽  
Glycolytic Intermediates ◽  
Phosphoglyceric Acid ◽  
Lactate And Pyruvate

1. The eggs of Echinus esculentus contain about 1.5% glycogen and 20% lipid (dry weight). 2. Whole eggs produce lactic acid under anaerobic conditions, the maximum rate of production being 0.15 pi. lactate/hr./mg. eggs (dry weight) at 20° C. 3. Lactic acid production is inhibited by fluoride, iodoacetate and phenylmercuric nitrate. 4. The supernatant from centrifuged egg homogenates prepared in M/50-phosphate buffer, pH 7.5, (‘extract’), was found to be a satisfactory glycolytic enzyme preparation. 5. The production of lactic and pyruvic acid by such extracts is greatly stimulated by the addition of glycogen, cozymase and adenosine triphosphate, (‘complemented extracts’). 6. Complemented extracts glycolyse glucose and fructose with greater facility than glycogen or starch. With glucose or fructose as substrate, the rate of formation of lactate and pyruvate may reach 1.7 µl./hr./mg. eggs (dry weight) at 20° C. 7. Complemented extract glycolysis is inhibited by fluoride, iodoacetate, phenylmercuric nitrate and phloridzin. 8. Active extract glycolysis occurs with the following glycolytic intermediates as substrates: glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate, hexose diphosphate and phosphoglyceric acid. 9. It is concluded that the sea-urchin egg (E. esculentus) possesses a typical glycolytic system, whose activity is comparable with that found in other invertebrate tissues.

Sign in / Sign up

Export Citation Format

Share Document