On the experimental hybridization of echinoids / by Cresswell Shearer, Walter de Morgan, and H.M. Fuchs.

Abstract

regard to the number of primary mesenchyme cells. He stated that doublefertilized eggs had an unecjual amount of mesenchyme in the two halves of the larvae, and that the mesenchyme was therefore influenced by the sperm. He found that the sperm aflected also the form, size, and pigmentation of the larvpe. In this controversy between Boveri andDRiKSCH it is very difficult to decide which was in the right, as tlie criteria used to determine the dominance were so questionable. Driesch, for example, suggested that BovERl used unhealthy larvas in which to count the mesenchyme cells, or that he counted in other cells with them. Peter (73) attributed these conflicting results to the great individual variation which he found in the number of mesenchyme cells within each species Again, the form of the larvae is a very doubtful point on which to decide the inheritance. Driesch stated that the shape of the larvae was maternal, except when influenced by the skeleton ; but Boveri claimed to have found paternal influence in the shape of very young larvae, before the development of the skeleton. He admits that the shape may be maternal, but Driesch states that it is always so. lu 1906, FiscHEL (27), working at Villefranche, crossed Arhacia jmstulosa, Echinwĥ r-evispinosus and Sti oiigyloceidroUis lividus. In opposition to Driesch, he concluded that tlie hybrids were not purely maternal, but that the sperm had, in many cases, an influence on tlie form, size, pigment, and skeleton. He regretted, liowever, that he

The American Arbacia and Other Sea Urchins

“…The Mitzschias themselves must be raised in pure culture and require a special diet, Miquel's solution^The method has been worked out by Allen and Nelson (1910) in Plymouth, England, and has been used by many investigators at the Plymouth laboratory. Shearer, de Morgan, and Fuchs (1914) have in this way succeeded not only in raising the normal plutei of several species of sea urchin to maturity, but have also raised some hybrid plutei to maturity. Fuchs (1914b) has even obtained the next or F2 generation of these hybrids. '…”

“…The food for the developing pluteus is diatoms, especially Nitzschia closterium which can be cultured with Miquel's solution (E. B. or more simply by adding 0.002% Na2HP04i2H20 + 0.01% KNO3 to sea water (see Part H). When the shell is developing, the calcareous material can be supplied by the calcareous protozoon Trichosphaerium and later by the red alga Corallina, according to Shearer, de Morgan, and Fuchs (1914).…”

“…Egg 180 /« Plymouth (Shearer, de Morgan,and Fuchs,19 14, p. 267) ; 145.9 fi Sweden (Borei, 1935 unpub. ) de Morgan, and Fuchs, 1914;p. 267).…”

“…Plutei have not been found in the tow above the beds. Morgan, and Fuchs (1914); the development of Psammechinus miliaris and Ps. microtuberculatus is similar (Mac-Bride, 1914a); Arbacia lixula and Paracentrotus lividus by von Ubisch (1913aUbisch ( , b, c, 1927Ubisch ( , 1932Ubisch ( , 1950; see also Busch ( 1849 (193 1, 1936).…”

A fibroblast cell culture model to study vitamin K metabolism and the inhibition of vitamin K epoxide reductase by known and suspected antagonists

“…A number of studies in rats (Creedon & Suttie, 1986: Uchida & Komeno. 1988) and humans (Bechtold et al 1984;Shearer et d. 1988) have suggested that the antagonistic effect of NMTT-containing antibiotics is directed towards vitamin K epoxide reductase though the active inhibitor remains unknown. Large doses of salicylate can also cause a coumarin-like hypoprothrombinaemia and this compound too appears to weakly inhibit the conversion of KO to K (Park & Leck.…”