5,5'-Biscalix[5]arene, prepared by oxidative coupling of the tetrabenzoyl ester of calix[5]arene (shown by X-ray crystallographic analysis to have a o,u,u,d,u conformation), forms complexes with C(60) (K(assoc) = 43 M(-)(1)) and C(70) (K(assoc) = 233 M(-)(1)). The X-ray crystallographic structure of the C(60) complex reveals its clamshell-shaped architecture, presumably the result of a change in the conformation of biscalix[5]arene from anti (uncomplexed) to syn (complexed).

There are several anecdotal reports of the American lobster Homarus americanus moving to deeper water, or suffering increased mortality, in response to storm events. It has also been reported that changes In salinity and temperature, similar to those result~ng from storm events, can elicit avoidance behaviors. In 1991, during an ongoing lobster study, Hurricane Bob caused a substantial drop in salinity in the Great Bay Estuary, New Hamphlre, USA. This freshet, and possibly related environmental perturbations, was associated with increased movement of lobsters down the estuary toward the coast and a rise in catch in areas closer to the coast. Thus, our data support the hypothesis that storms can induce movements of lobsters and subsequent transient shifts in the demographics of the lobster population.

No abstract

1. The morphology and innervation of the midgut (intestine) in the horseshoe crab, Limulus polyphemus was investigated. The organization of this tissue was examined with routine histology. Radioimmunoassay, immunohistochemistry and high performance liquid chromatography were employed to detect, localize and identify peptidergic innervation of the midgut. The actions of synthetic and native proctolin-like and FMRFamide-like peptides were compared on the isolated midgut preparation. 2. Levels of proctolin and FMRFamide were determined in extracts of Limulus midgut tissue using radioimmunoassay. High levels of proctolin-like immunoreactivity (69.5 +/- 11.3 ng/g) were detected, while levels of FMRFamide-like immunoreactivity (0.8 +/- 0.2 ng/g) were less. Proctolin levels were equally distributed, while the levels of FMRFamide-like immunoreactivity exhibited an anterior bias. 3. Proctolin- and FMRFamide-like immunoreactivities in the Limulus midgut were localized with immunohistochemistry. Proctolin- and FMRFamide-immunoreactive elements were detected in intestinal nerve branches and individual fibers running along the surface of the midgut in whole-mount preparations. In sectioned tissue, staining for these peptides was observed throughout the midgut, typically associated with muscle bands and fibers. Only a few immunoreactive cell bodies were observed. 4. Proctolin, and several FMRFamide-like peptides produced distinct and opposing actions on the isolated Limulus midgut preparation. Proctolin elicited contracture and rhythmic contractions of this tissue, while FMRFamide and N-terminally extended analogs of FLRFamide relaxed gut tension. FMRFamide-like peptides partially reversed the excitatory actions of proctolin. 5. Proctolin- and FMRFamide-like peptides in Limulus midgut extracts were partially characterized with high performance liquid chromatography. One peak of proctolin-like activity was detected on a linear gradient of 18 to 31.5% acetonitrile. The native proctolin-like peptide produced excitatory actions on the isolated midgut preparation which were indistinguishable from those produced by synthetic proctolin. Several peaks of FMRFamide-like bioactivity (Busycon radula protractor muscle assay) were detected with a linear gradient of 5 to 30% acetonitrile. Fractions from two distinct peaks produced FMRFamide-like inhibitory effects on the isolated Limulus midgut preparation. These findings suggest a role for proctolin-like and FMRFamide-like peptides as regulators of intestinal motility in Limulus.

Every year, more than 600000 horseshoe crabs are bled to produce Limulus amoebocyte lysate, which is used to detect Gram-negative bacteria in biomedical products. While numerous studies have shown that some horseshoe crabs die after being bled, less is known about what happens to those that are returned to their natural habitat. In this study, we used an array of VR2W acoustic receivers to track 10 bled and 10 control females during the mating season in the Great Bay Estuary, NH, USA. Animals were bled, or not, released where they had been initially captured, and tracked from 22 May to 26 June 2019. Bled and control females moved comparable distances at similar speeds during the weeks after they were released (controls: 90.3 m h-1; bled: 89.7 m h-1). The longer horseshoe crabs remained within the virtual positioning system array, the longer we were able to track them and the more beach approaches and mating attempts we were able to identify. When this relationship between the duration of time we were able to track a horseshoe crab and how many apparent mating attempts it expressed was taken into account, we found that bled females attempted to spawn half as often as control females, and this difference was significant. Overall, these data are consistent with previous findings indicating that females that are released back into their natural habitat after bleeding express similar levels of activity and seasonal movements but attempt to mate less than control animals, at least in the first few weeks after being bled.