ANTISERA THAT BLOCK CELL DIVISION IN DEVELOPING EGGS OF SEA URCHINS

Spermine is major polyamine in sea urchins: studies of polyamines and their synthesis in developing sea urchins.

Polyamine synthesis and accumulation was studied in several species of developing sea urchins. Most striking is the presence in the gametes of a large amount of spermine, with low amounts of putrescine and spermidine. This contrasts with the pattern of polyamines present in both micro-organisms and mammals. Micro-organisms contain mainly putrescine and spermidine and adult mammalian tissues usu...

The Action of Various Anaesthetics in Sup- Pressing Cell-division in Sea-urchin Eggs

The Pyruvate Metabolism of Sea Urchin Eggs during the Process of Cell Division

The eggs of Arbacia and starfish contained about 70 and 25 micrograms of pyruvate per gm. of dry cells respectively. Arbacia eggs utilized added pyruvate, although the O(2) uptake did not increase. On fertilization the utilization of pyruvate increased sevenfold. This pyruvate seems to be metabolized, as in other cells, with diphosphothiamine as coenzyme. The diphosphothiamine content of fertil...

Further Studies on Cell Division without Mitotic Apparatus in Sea Urchin Eggs

A large quantity of paraffin oil, sucrose solution, or sea water was injected into the eggs of the heart urchin Clypeaster japonicus shortly before the onset of the first cleavage. The injected oil became spherical, pushing the mitotic apparatus aside. The sucrose solution mixed with the protoplasm and caused disintegration of the mitotic apparatus, and the sea water formed a vacuole at the cen...

REpROdUCTIvE ISOLATION BETwEEN SpECIES OF SEA URChINS

Existing knowledge on reproductive isolating barriers between sea urchin species is reviewed. Experiments involving artificial production of hybrids between congeneric echinoid species have shown that in most cases hybrids are viable and capable of backcrossing. Only species separated for > 5 million yrs show complete post-zygotic isolation. Each potential prezygotic isolating barrier appears t...