Several allergic manifestations due to sea urchins are reported in the literature. Allergy due to consumption of gonads (roe) of sea urchins in some people is well known. Accidental stepping on this spiny creature, near the shallow rocky places of the sea which is its habitat, causing allergy has been reported. Workers employed in the roe production units, fishermen and scuba divers are at spec...

The separation and purification of histone H1 from the sperm of the sea-urchin Sphaerechinus granularis is described. Physical studies were used to compare this histone H1 molecule with H1 histones from other species. C.d. and 270 MHz n.m.r. spectroscopy indicate that, despite significant compositional differences from other sea-urchin sperm H1 histones, their secondary and tertiary structures ...

As gene regulatory network models encompass more and more of the specification processes underlying sea urchin embryonic development, topological themes emerge that imply the existence of structural network 'building blocks'. These are subcircuits which perform given logic operations in the spatial control of gene expression. The various parts of the sea urchin gene regulatory networks offer in...

X-ray absorption microtomography, a high resolution variant of medical “CT”, and synchrotron x-ray phase contrast imaging reveal the distribution of mineral within teeth of the sea urchin Lytechinus variegatus. Data from these imaging modalities on intact teeth are compared with histochemically stained thin sections observed with transmission optical microscopy. Because these teeth grow continu...

We have found that cytoplasmic extracts from unfertilized sea-urchin eggs contain a prominent microtubule-activated ATPase activity. This activity is induced by polymeric tubulin, but not by tubulin subunits. The activity cosediments with taxol-stabilized microtubules in an ATP-independent manner. We have separated the ATPase from cytoplasmic dynein and other ATPases on sucrose gradients. The s...

1. Penicillin in the range of concentration from 250 U/ml. to approximately 2650 U/ml. inhibits the rate of cell division of the fertilized sea urchin egg from 0 to 100 per cent. 2. Penicillin in the same range of concentrations has no effect on the oxygen consumption of the unfertilized or the fertilized eggs. 3. Penicillin is bound by some component of the sea urchin egg in amounts sufficient...

We describe the Hox cluster in the radially symmetric sea urchin and compare our findings to what is known from clusters in bilaterally symmetric animals. Several Hox genes from the direct-developing sea urchin Heliocidaris erythrogramma are described. CHEF gel analysis shows that the Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA, and only a single cluster is present, as...

The European purple sea urchin (Paracentrotus lividus) is considered to be a key herbivore throughout its distribution range--North-East Atlantic and Mediterranean Sea. It was also abundant in its eastern distributional edge, on rocky habitats of the coastline of Israel, but its populations have recently collapsed, and today it is an extremely rare species in the region. Field and laboratory ex...

The chemokine system has a critical role in mammalian immunity, but the evolutionary history of chemokines and chemokine receptors are ill-defined. We used comparative whole genome analysis of fruit fly, sea urchin, sea squirt, pufferfish, zebrafish, frog, and chicken to identify chemokines and chemokine receptors in each species. We report 127 chemokine and 70 chemokine receptor genes in the 7...

How the combination of positive and negative species interactions acts to drive community dynamics is a fundamental question in ecology. Here we explore one aspect of this question by expanding the theory of predator-mediated coexistence to include the potential role of facilitation between the predator and inferior competitor. To motivate and illustrate our simple model, we focus on sea-urchin...