Limulus vision in the ocean day and night: effects of image size and contrast.

Male horseshoe crabs, Limulus polyphemus, use their eyes to locate mates day and night. We investigated their ability to detect targets of different size and contrast in a mating area of Buzzards Bay, Cape Cod, MA. We found that males can see large, high-contrast targets better than small, low-contrast ones.

Sulfide as a Chemical Stimulus for Deep-Sea Hydrothermal Vent Shrimp.

Organisms dependent on deep-sea hydrothermal vents for their existence face extinction when their vents expire, unless they can establish populations on neighboring vents or on new vent sites. Propagules, including larvae and motile adults, are readily dispersed broadly by seafloor currents, but how they recognize active hydrothermal sites is problematical. Compelling evidence that vent organisms can find and colonize hydrothermal sites has been provided by a series of observations on the East Pacific Rise (1).

The morphology of the dorsal eye of the hydrothermal vent shrimp, Rimicaris exoculata.

The bresiliid shrimp, Rimicaris exoculata, lives in large masses on the sides of hydrothermal vent chimneys at two sites on the Mid-Atlantic Ridge. Although essentially no daylight penetrates to depths of 3500 m, very dim light is emitted from the hydrothermal vents themselves. To exploit this light, R.

Translation of the second gene of peanut clump virus RNA 2 occurs by leaky scanning in vitro.

The two 5'-proximal open reading frames of peanut clump virus RNA 2, which encode the coat protein of 23 kDa and a protein of 39 kDa (P39), are both translated in vitro from genomic RNA 2. We have studied the translational strategy involved in the initiation at the second AUG of RNA 2, which is the initiation codon of P39. Mutation experiments with synthetic transcripts corresponding to the 5'-half of RNA 2 ruled out mechanisms of P39 translation initiation involving termination-reinitiation and internal ribosomes entry.

Complete nucleotide sequence of peanut clump virus RNA 1 and relationships with other fungus-transmitted rod-shaped viruses.

The complete nucleotide sequence of RNA 1 of the tentative furovirus peanut clump virus (PCV) has been determined by characterization of cloned cDNA and by direct RNA sequencing. The sequence is 5897 nucleotides in length and contains three long open reading frames (ORFs). The 5'-terminal proximal ORF has the potential to encode a polypeptide of M(r) 130942 (P131) containing methyltransferase and RNA helicase homologous domains and displaying homology with large nonstructural proteins of alpha-like viruses, which are known or thought to be involved in virus replication.

The Limulus-eye view of the world.

The compound lateral eye of the adult horseshoe crab, Limulus polyphemus, views the world with approximately 1000 ommatidia. Their optical properties and orientation determine the eye's resolution, field of view, and light collecting ability. Optic axes of adjacent ommatidia diverge from 1-15 deg with an average value of 5.

Partial inhibition of polysomal ribosomes of Escherichia coli by streptomycin.

With purified initiation-free polysomes of E. coli, whether endogenous or formed in vitro on phage R17 RNA, streptomycin causes partial inhibition of chain elongation. The degree of inhibition is constant over a broad range of streptomycin concentration and decreases markedly with increasing Mg(++) concentration.