Transport of Oxygen by the Blood of the Land Crab, Gecarcinus lateralis

Parameters relating to transport of oxygen were measured inthe pericardial blood and venous outflow from the first walkingleg of Gecarcinus lateralis. O₂-equilibrium curves of the hemocyaninof G. lateralis were found to be sigmoid and, at 27°C andpH 7.45, to have a half-saturation pressure of about 17 mm Hgoxygen. Average partial pressures of oxygen as measured by O₂-electrodewere 32 mm Hg in pericardial blood and 9 mm Hg in the venoussamples. Analysis of the O₂-content in corresponding samplesby the Van Slyke technique revealed an average of 2.17 volumes% O₂-capacity for whole blood, 1.45 volumes % for pericardialblood, and 0.61 volumes % for venous blood. Estimates basedon the Van Slyke analyses indicated an average pO₂ of 29 and14 mm Hg in pericardial and venous samples, respectively. Thesefigures agree fairly well with those obtained by means of O₂-electrodes.Of the oxygen carried to the tissues, about 94% is carried asoxyhemocyanin and about 6% is carried in physical solution.As the blood passes through the gills, the hemocyanin, on anaverage, becomes 80–85% saturated with oxygen and returnedfrom the tissues 18–45% saturated with oxygen. These resultsindicate that the blood of G. lateralis has a higher O₂-capacitythan the blood of most other decapod crustaceans for which similarinformation is available. In addition, the blood of G. lateralistransports more oxygen to the tissues per unit volume than doother crustacean bloods.     

Expression and characterization of ovine major histocompatibility complex class II (OLA-DR) genes

Previous work made use of nucleic acid probes corresponding to different subtypes of the class II regions of the human and murine major histocompatibility complex (MHC) to isolate seven different alpha and 24 different beta genes of the ovine MHC from two cosmid libraries. In an attempt to identify pairs of alpha and beta genes capable of cell surface expression, all permutations of alpha and beta genes were in turn transfected into mouse L-cells. Two pairs of alpha and beta genes co-expressed and stable ovine MHC class II L-cell lines were developed. The expressed alpha genes had previously been defined as DR-alpha homologues (DRA) by differential Southern hybridization to human subtype specific class II probes. The expressed ovine beta genes were also assigned as ovine DR-beta homologues (DRB) on the basis of their sequence having a higher degree of similarity with human DRB than any other subtype. A total of eight out of 23 anti-sheep class II specific monoclonal antibodies were typed OLA-DR specific by FACScan analysis using the L-cell lines.     

Multimodal alarm behavior in urban and rural gray squirrels studied by means of observation and a mechanical robot

Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is un-known how urbanization has affected these behaviors. Multimodal communication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be pre-sented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Parian et al. (2009) by providing data on sig-naling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifies are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats.