A Bilaterally Partitioned Colour Variant of an Appalachian Brook Crayfish (Cambarus bartonii bartonii) from eastern Pennsylvania

This observation of a bilaterally partitioned colour phenotype of an Appalachian Brook Crayfish (Cambarus bartonii bartonii) from Fishing Creek, Columbia County, Pennsylvania, USA, appears to be the first report of such an aberrant phenotype for this species. The pattern is similar to that reported previously in Papershell Crayfish (Orconectes immunis) and Ameri can Lobster (Homarus americanus). Although the cause of the colour pattern in the specimen of C. b. bartonii could not be determined, hypotheses related to previous cases in aquatic crustaceans include bilateral partition of primary and secondary sexual characteristics (bicoloured gynandromorphy) and mutation during embryogenesis

A Crayfish Survey of the Fishing Creek Watershed in Northeastern Pennsylvania

Introductions of invasive crayfish species have impacted freshwater ecosystems worldwide, typically resulting in displacement of native crayfish species by non-native species. Two crayfish species (Orconectes limosus and Cambarus bartonii) are thought to be native to the Susquehanna River Drainage in eastern and central Pennsylvania. However, several non-native crayfish (e.g., O. obscurus, O. rusticus, O. virilus) have been introduced and have become established in this river system. Few data are available on the present occurrence and distribution of crayfish species within the Fishing Creek watershed, a drainage encompassing approximately 620 km2 within the North Branch Susquehanna River Drainage in eastern Pennsylvania. Records from the early 1900s report the occurrence of both O. limosus and C. bartonii in this watershed; however, recent point-surveys in the lower reaches of the watershed have reported the presence of the non-native crayfish Orconectes obscurus. In this work, crayfish were sampled at fifteen sites from the lower reaches of Fishing Creek to its headwater branches and major tributaries in order to elucidate the current presence and distribution of crayfish species within this watershed. A total of 484 crayfish were collected, representing the species O. obscurus (n = 376) and C. bartonii (n = 108). O. obscurus were found to be widespread within the drainage, but absent from the upper reaches of the Fishing Creek watershed, potentially as a result of physical or environmental barriers (e.g., dams, shifting stream characteristics). C. bartonii were primarily distributed in the upper portions of the Fishing Creek watershed, but also found in smaller tributary near the mouth, and sympatric (but in found in low abundance) with O. obscurus in the central portions of the drainage. This distribution of C. bartonii within the watershed is likely due to habitat preferences (e.g., cooler, smaller, and higher gradient portions of streams) of this species, but may also result from displacement by O. obscurus. The historically present O. limosus was not collected within the watershed, potentially suggesting local extirpation via competition with O. obscurus, as has been reported in other elsewhere in aquatic ecosystems invaded by non-native congeners

Acclimation and Care of Eastern Hellbender Salamanders (Cryptobranchus alleganiensis alleganiensis) in a Captive Setting

Few data are available regarding captive acclimation of Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis), large, imperiled, fully aquatic salamanders native to the eastern United States. However, ex situ research may be necessary to evalu

A Ca2+-activated Cl− conductance in interstitial cells of Cajal linked to slow wave currents and pacemaker activity

Interstitial cells of Cajal (ICC) are unique cells that generate electrical pacemaker activity in gastrointestinal (GI) muscles. Many previous studies have attempted to characterize the conductances responsible for pacemaker current and slow waves in the GI tract, but the precise mechanism of electrical rhythmicity is still debated. We used a new transgenic mouse with a bright green fluorescent protein (copGFP) constitutively expressed in ICC to facilitate study of these cells in mixed cell dispersions. We found that ICC express a specialized ‘slow wave’ current. Reversal of tail current analysis showed this current was due to a Cl− selective conductance. ICC express ANO1, a Ca2+-activated Cl− channel. Slow wave currents are not voltage dependent, but a secondary voltage-dependent process underlies activation of these currents. Removal of extracellular Ca2+, replacement of Ca2+ with Ba2+, or extracellular Ni2+ (30 μm) blocked the slow wave current. Single Ca2+-activated Cl− channels with a unitary conductance of 7.8 pS were resolved in excised patches of ICC. These are similar in conductance to ANO1 channels (8 pS) expressed in HEK293 cells. Slow wave current was blocked in a concentration-dependent manner by niflumic acid (IC50= 4.8 μm). Slow wave currents are associated with transient depolarizations of ICC in current clamp, and these events were blocked by niflumic acid. These findings demonstrate a role for a Ca2+-activated Cl− conductance in slow wave current in ICC and are consistent with the idea that ANO1 participates in pacemaker activity