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At least 37 records · Page 2Linked to original sources
PubMed1979

Change in the fructose 1,6-bisphosphatase activity in sea urchin eggs following fertilization.

The activity of fructose 1,6-bisphosphatase [EC 3.1.3.11] in sea urchin eggs decreased following fertilization. During the first 30 min after fertilization, the activity was considerably lower than that in unfertilized eggs, but by 30 min the activity was similar to that in unfertilized eggs. The enzyme activity in fertilized eggs, estimated in the presence of EGTA, was similar to that in unfertilized eggs. The activity in unfertilized eggs was reduced by Ca2+ at concentrations between 1 X 10(-5) M and 5 X 10(-3) M. Immediately after fertilization, the enzyme was insensitive to concentrations of Ca2+ lower than 2 X 10(-4) M, but the Ca2+ sensitivity of the enzyme recovered 30 min after fertilization. In the presence of Ca2+ at concentrations higher than 2 X 10(-4) M, the enzyme activity in unfertilized eggs was similar to that in fertilized eggs. Mg2+ restored the Ca2+-induced inhibition of fructose 1,6-bisphosphatase. 3-Phosphoglycerate and citrate hardly affected the enzyme activity, and AMP at concentrations above 10 mM inhibited it.

Adenosine Monophosphate↗
PubMed1977

Experimental activation of ascidian eggs.

The effects of the ionophore A23187 on the activation of the eggs of Ascidia malaca have been studied. No common external ion in the sea water is found to be essential for the activation but lanthanum and manganese inhibit the response. These observations support the interpretation that activation of these eggs results from changes in free intracellular calcium levels. This has led to the prediction of two other activating treatments, namely high external calcium and addition of theophylline.

Animals↗
PubMed1979

Accelerated mouse sperm penetration in vitro in the presence of caffeine.

Evidence for accelerated mouse sperm penetration into eggs in vitro, and hence for accelerated capacitation, was obtained when the fertilizing ability of sperm suspensions was tested after preincubation, for a period of time insufficient to permit full capacitation under standard conditions, in the presence or absence of caffeine. When eggs were fixed after 1 h, the majority (76.7%) in the caffeine-containing medium were fertilized compared with only 32.1% in the caffeine-free medium. When fixation was later, after 1 h 15 min, fertilization levels were high (approximately 90%) in both groups, but significant differences in the stages of egg activation and sperm head decondensation reached were observed. In the absence of caffeine, early stages of nuclear development were predominant, while in the presence of caffeine, a significant proportion of eggs had reached terminal stages of activation. There was also some evidence for precocious sperm, but not egg, nuclear development when fertilization occurred in caffeine-containing medium.

Animals↗
PubMed1979

Rate of fertilization in vitro and subsequent nuclear development as a function of the post-ovulatory age of the mouse egg.

Evidence is presented to indicate that older mouse eggs are fertilized more rapidly and also develop more rapidly to the pronuclear stage than younger ones. After a low (1.5 i.u.) or a high (7.5 i.u.) dose of PMSG, female mice were killed 13 or 17 h after hCG. The eggs were mixed in vitro with preincubated spermatozoa and fixed 1--1 1/4 h later. Although fertilization levels were high in all groups, the stages of egg activation and sperm head decondensation differed significantly. The observed ranking, from most to least rapid fertilization, of eggs obtained from females treated with 7.5 i.u. and killed 17 h after hCG, 1.5 i.u. and 13 h, and 7.5 i.u. and 13 h, was consistent with the approximate length of time the eggs had resided in the oviduct, i.e. the longer that time period, the more rapid the fertilization. When eggs were fixed 4 1/4 h after mixing with spermatozoa, the majority of older eggs were fully pronuclear while only a few of the younger eggs were as advanced, indicating accelerated nuclear development in the cytoplasm of the older eggs.

Animals↗
PubMed1977

The dynamics of maternal poly(A)-containing mRNA in fertilized sea urchin eggs.

Cytoplasmic polyadenylated RNA with the characteristics of sequestered mRNA exists in the unfertilized sea urchin egg. Following egg activation, the amount of poly(A) doubles, but total RNA content stays constant. Chromatography of the RNA on poly(U)-Sepharose shows that the amount of RNA that bears a poly(A) tract increases slightly (approximately 20-30%) during the 2 hr after fertilization. When a cDNA transcript of the poly(A)+ mRNA from 2 hr zygotes is reacted against poly(A)+ RNA from either eggs or zygotes, the kinetics of reassociation of the two preparations seem identical; hence the RNA sequences bearing poly(A) are the same in eggs and zygotes. Measurement of the length of the poly(A) tract in eggs and zygotes shows an increase in number average length from about 45 bases to 60 bases. Measurement of tract length of poly(A) in two cell zygotes by adenosine/AMP ratios of radioactive RNA shows that the poly(A) tract of the zygote is solely accounted for radioactive RNA, indicating extensive turnover of the poly(A). It is concluded that the poly(A) tract in these cells is subject to both lengthening and shortening, with the former predominating in this instance. the increase in poly(A) does not involve polyadenylation of different sequences, but is due to an increase in the number of polyadenylated sequences and the length of the poly(A) tracts that they bear.

Animals↗
PubMed1977

Activation of hamster eggs by pricking.

When mature unfertilized eggs of the golden hamster were picked with a glass needle, nearly 80% of them were activated. The diameter of needle was of critical importance for the successful induction of activation. It appeared that extracellular calcium was not necessary for the establishment (reception) of stimulation by pricking but was necessary for later phases of activation. The possible mechanisms by which pricking with a needle triggers the activation of the egg were compared with the mechanisms by which divalent ionophore induces activation.

Animals↗
PubMed1978

Bacteriuria in urinary schistosomiasis in Egypt a prevalence survey.

An epidemiologic survey to assess the prevalence of bacteriuria in urinary schistosomiasis was carried out in a region endemic for urinary schistosomiasis in Egypt. Twenty of 390 (5.1%) school boys aged 5--16 years were bacteriuric. This prevalence rate is more than 10 times greater than that found in comparable surveys in areas non-endemic for urinary schistosomiasis. In this endemic population bacteriuria was found in 6.5% of active egg excreters and 2.3% of non-egg excreters.

Adolescent↗
PubMed1977

Effect of dietary DL-ethionine and/or DL-methionine on egg laying and activities of some cytoplasmic NAD linked-dehydrogenases and NADPH-producing enzymes in liver of Japanese quail, Coturnix coturnix japonica.

The effect of dietary DL-ethionine and/or DL-methionine on egg laying, and activities of some NAD linked-dehydrogenases and NADPH-producing enzymes in liver of Japanese quail, Coturnix coturnix japonica was investigated. A 0.30% DL-ethionine plus 0.30% DL-methionine supplemented diet reversed partially the egg laying inhibited by the diet with 0.30% DL-ethionine alone. No inhibitory effect on egg laying was observed for the diet supplemented with 0.30% DL-methionine alone. In marked contrast to the decreased activity of L-glycerol 3-phosphate dehydrogenase and malate dehydrogenase, significantly increased activity of lactate dehydrogenase was obtained for quail fed the DL-ethionine, and the DL-ethionine plus the DL-methionine supplemented diet, respectively. No marked changes in activities of these three dehydrogenases were obtained for quail fed the diet supplemented with DL-methionine alone. Although decreased activity was observed for all of the four NADPH-producing enzymes in quail fed the diet supplemented with DL-ethionine alone, the DL-ethionine plus DL-methionine, the smallest decrease was obtained for NADP-isocitrate dehydrogenase. The diet supplemented with DL-methionine alone induced markedly the respective activity of malic enzyme and glucose 6-phosphate dehydrogenase. These results indicate a relatively important function of NADP-isocitrate dehydrogenase for NADPH-production even under DL-ethionine toxicity and suggest complicated relationships between egg production and activities of enzymes associated with carbohydrate and lipid metabolism in quail liver.

Alcohol Oxidoreductases↗
PubMed1978

Egg surface glycoprotein receptor for sea urchin sperm bindin.

Bindin is an insoluble protein coating the sperm acrosome process and mediating the adhesion of sperm to sea urchin eggs. Milligrams of bindin have been isolated. Here we report the identification, isolation, and partial characterization of a high molecular weight, trypsin-sensitive glycoprotein fraction from the sea urchin egg surface having species-specific affinity for bindin. This glycoprotein may be the egg surface receptor for bindin. The bindin receptor was released from 125-I-labeled eggs by parthenogenetic activation of eggs with ionophore A23187 in the presence of soybean trypsin inhibitor. The receptor has an isoelectric point of 4.02 and a molecular weight in sea water greater than or equal to 5 X 10(6), suggesting that it is an aggregate. It contains 34% neutral sugars, which are galactose and mannose.

Adhesiveness↗
PubMed1978

Electrical activity of the oviduct of the laying hen during egg transport.

Electrical activity in the oviduct wall of the laying hen was studied. The frequency of spike discharges increased in the magnum and isthmus when the egg approached close to the recording sites. The frequency of discharge remained high in the magnum until the egg had passed, but it decreased in the isthmus during the stay of the egg. In the uterus, a relatively high activity was found immediately after oviposition and this was followed by low activity for about 5 h. Electrical activity began to increase again and reached maximum 1-2 h after the egg entered the uterus. The direction of propagation of electrical activity in the magnum was determined by using two electrodes and was towards the ovary or towards the uterus for periods of several minutes.

Action Potentials↗
PubMed1978

Evidence for mediation of a neuronal interaction by a behaviorally active peptide.

Egg laying hormone, a peptide neurohormone with an approximate molecular weight of 6000, was isolated from the region of the abdominal ganglion of Aplysia that contains the neuroendocrine bag cells and purified by gel filtration chromatography, isoelectric focusing, and dialysis. A 1-min local application of egg laying hormone to the identified neuron R15 produced prolonged (greater than 1 hr) augmentation of impulse activity in this neuron. The distinctive quality and prolonged duration of the response are apparently identical to the previously described response to electrically elicited bag cell activity. The results provide evidence that egg laying hormone is the mediator of this prolonged neuronal interaction.

Animals↗
PubMed1978

[Cortical reaction in starred sturgeon eggs following fertilization and artificial activation].

An electron microscopical study of the fertilized sevryuga eggs has shown that 3 sec after insemination the most cortical granules in the region of the animal pole are already dehiscing and 10 to 30 sec the cortical granules release their contents under the membrane, but between the groups of cortical granules the contact of the cytoplasm with the membrane is still preserved. The full separation of the membrane observed under the light microscope at these times of fixation (San Felice fluid) is an artifact due to changes in the cortical cytoplasm properties. The rate of spreading of the cortical reaction over the egg surface is reduced from the animal pole to the vegetative one. By the criterion of the first changes discernible under the light microscope (formation of vacuoles and cytoplasmic threads between them) the maximal rate in the region of the animal pole amounts 360.5 mcm/sec and the average rate of the whole egg 46.5 mcm/sec; by the criterion of membrane separation the average rate amounts to 26.8 mcm/sec (at the temperature 21.9 degrees). The average rate of spreading of the cortical reaction in the sevryuga eggs is close to that in the sturgeon (Acipenser güldenstädti) and exceed ca. 3 times that in the sea urchin and teleostean eggs. The cortical reaction spreads at the same rate both in the fertilized and activated sevryuga eggs.

Animals↗