On the Rate of Oxygen Consumption by Fertilized and Unfertilized Eggs

Abstract

Measurements have been made of the rates of oxygen consumption by the eggs of several marine forms, and especially of the change in rate following fertilization. It is convenient to present some of these results separately, considering them comparatively in one of the papers and discussing the relation to other work in the field, and some of the theoretical implications. This will be done in the fourth paper (1) of this series. The present paper will be chiefly concerned with measurements on the eggs of the clam Cumingia.In the summer of 1930 measurements of the rate of oxygen consumption of Chaetopterus eggs showed that immediately following fertilization there is a decided decrease to slightly more than half of the prefertilization rate. This surprising result was entirely unexpected, and many careful repetitions of the measurements were made, which invariably confirmed the first finding. When the eggs of Chaelopterus are taken from the parapodia of the female and are placed in sea water, dissolution of the germinal vesicle takes place and maturation proceeds until the nucleus comes to rest in the metaphase of the first polar spindle. This takes less than 15 minutes at 20°C. In this stage the egg rests until it is fertilized. When the unfertilized eggs are placed in manometers after having attained the metaphase resting condition, the rate of oxygen consumption is uniform for at least 8 hours. Fertilization at any time during this period (which was the longest experimental period) causes a sharp drop to about half.

The effect of egg size on hatch time and metabolic rate: theoretical and empirical insights on developing insect embryos

“…Once the oocyte has become a 'ripe' unfertilized egg, respiration rate falls (Borei 1948) and meiotic growth is halted (Went 1982). Depending on the species, ripe eggs may remain viable in this state for several days (Whitaker 1931;Holcomb et al 2004) and, although meiotically halted, may be far from inactive. Measurable oxygen consumption rates have been observed in unfertilized eggs for a variety of species (Whitaker 1931;Borei 1948;Horwitz 1965;Tyler, Tyler & Piatigorsky 1968;Davenport & Lonnig 1980) and may indicate the generation of energy through the Krebs Cycle.…”

“…Depending on the species, ripe eggs may remain viable in this state for several days (Whitaker 1931;Holcomb et al 2004) and, although meiotically halted, may be far from inactive. Measurable oxygen consumption rates have been observed in unfertilized eggs for a variety of species (Whitaker 1931;Borei 1948;Horwitz 1965;Tyler, Tyler & Piatigorsky 1968;Davenport & Lonnig 1980) and may indicate the generation of energy through the Krebs Cycle. Unfertilized eggs contain all the necessary components of protein synthesis, including mRNAs (Tyler 1963;Tyler et al 1968) and evidence of protein synthesis has been demonstrated in ripe, unfertilized eggs of sea urchins (Tyler, Tyler and Piatigorsky 1968), clams (Bell & Reeder 1967), polychaete worms (Gould 1969) and frogs (Smith, Ecker & Subtelny 1966).…”

“…There is also physiological evidence that the growth of structure from reserve may initiate quite soon after fertilization, further supporting the assumption that a freshly fertilized egg should be modelled with some amount of structure. Within the first few hours after fertilization, respiration may increase exponentially until respiration rate has nearly doubled (Boyd 1928;Whitaker 1931;Borei 1948). Respiration rate may also increase dramatically within the first few minutes after fertilization, up to three times the rate of respiration in the unfertilized egg, but falling again within minutes (Horwitz 1965).…”

“…For example, plant seeds (analogous to eggs in DEB theory) may lay dormant for years before development begins. However, there also exists evidence which does not support this assumption, such as substantial oxygen consumption rates in unfertilized eggs (Whitaker 1931;Borei 1948;Horwitz 1965;Tyler, Tyler & Piatigorsky 1968;Davenport & Lonnig 1980). This evidence will be discussed later in more detail.…”

The Change in Osmotically Inactive Fraction Produced by Cell Activation

“…It may be pointed out moreover at this juncture that the direction of the change in b in Chaetopterus and Arbacia parallels the direction of respiratory change (oxygen uptake). Ckaetopterus exhibits a decline in rate of oxygen uptake on fertilization (Whitaker (1933)), and Arbacia shows an increase (various investigators). The parallelism between the increase in oxygen uptake and the increase in o.i.f, which occurs when the Arbacia egg is broken into halves by centrifugal force has been pointed out earlier in this paper.…”