Analysis and cytologic characterization of hemocytes from freshwater mussels (Quadrula sp.)

Background: Freshwater mussels are among the most endangered taxa in North America and minimally invasive techniques to evaluate their health are needed. Objective: The objective of this study was to develop a standardized approach for identifying and enumerating the cellular components of freshwater mussel hemolymph. Methods: Hemocyte clumping, total hemocyte count, and hemocyte morphology were compared in untreated hemolymph or hemolymph treated with formalin, sodium citrate, sodium heparin, EDTA, water, or l ‐cysteine. Morphology was then used to categorize hemocytes and perform a 100‐cell differential. Results: Treatment with formalin or >25 mg/mL l ‐cysteine reduced hemocyte clumping, although only formalin significantly increased the total hemocyte count. However, formalin also induced crenation that impaired hemocyte identification. Both EDTA and sodium citrate‐induced hemocyte degranulation while sodium citrate and >40 mg/mL l ‐cysteine‐induced cell lysis. Hemocytes could be categorized into 2 groups of granulocytes (eosinophilic or basophilic) and 2 groups of agranulocytes (large or small) for performing a cytologic differential. The differential was not significantly altered by anticoagulant treatments providing cell morphology was adequate for obtaining a differential. Eosinophilic granulocytes predominated (59%) with fewer large agranulocytes (27%) and basophilic granulocytes (13%). Small agranulocytes comprised 2% of the total population. Conclusions: No single treatment provided an optimal method to evaluate freshwater mussel hemolymph. Maximal hemocyte counts were obtained following formalin treatment. l ‐cysteine reduced clumping and maintained hemocyte morphology for performing a cytologic differential. These techniques provide a standardized approach for the hematologic evaluation of freshwater mussels.     

Subsurface radar sounding of the south polar layered deposits of Mars

The ice-rich south polar layered deposits of Mars were probed with the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the Mars Express orbiter. The radar signals penetrate deep into the deposits (more than 3.7 kilometers). For most of the area, a reflection is detected at a time delay that is consistent with an interface between the deposits and the substrate. The reflected power from this interface indicates minimal attenuation of the signal, suggesting a composition of nearly pure water ice. Maps were generated of the topography of the basal interface and the thickness of the layered deposits. A set of buried depressions is seen within 300 kilometers of the pole. The thickness map shows an asymmetric distribution of the deposits and regions of anomalous thickness. The total volume is estimated to be 1.6 x 10(6) cubic kilometers, which is equivalent to a global water layer approximately 11 meters thick.     

Return to Mercury: a global perspective on MESSENGER's first Mercury flyby

In January 2008, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft became the first probe to fly past the planet Mercury in 33 years. The encounter revealed that Mercury is a dynamic system; its liquid iron-rich outer core is coupled through a dominantly dipolar magnetic field to the surface, exosphere, and magnetosphere, all of which interact with the solar wind. MESSENGER images confirm that lobate scarps are the dominant tectonic landform and record global contraction associated with cooling of the planet. The history of contraction can be related to the history of volcanism and cratering, and the total contractional strain is at least one-third greater than inferred from Mariner 10 images. On the basis of measurements of thermal neutrons made during the flyby, the average abundance of iron in Mercury's surface material is less than 6% by weight.     

The geographer as radical humanist: an appreciation of Keith Buchanan

Keith McPherson Buchanan, Emeritus Professor and first Professor of Geography at Victoria University, recently died at the age of 78. Buchanan was a prolific writer, polemicist, reviewer and commentator. His work includes nine books plus two co-authored volumes, well over 200 articles and comments, and a very large number of book reviews. As a radical geographer, a socialist, a champion of the dispossessed, and an unrelenting critic of orthodoxy, capitalist regimes and power elites, Buchanan was always controversial. His work represents a powerful case directed against some of the great evils and dangerous trends shaping the later twentieth century world. As one of the founders of this journal Asia Pacific Viewpoint (originally Pacific Viewpoint) Keith Buchanan along with his colleagues in the sixties helped establish the Wellington Department of Geography as a centre of innovative research and writing on Asia and the Third World. In this reflection on the man and his work former colleague Ray Watters argues that although best known for his work on China Buchanan’s greatest contribution was as a radical polemicist and essayist on contemporary issues.     

Volcanism on Mercury: evidence from the first MESSENGER flyby

The origin of plains on Mercury, whether by volcanic flooding or impact ejecta ponding, has been controversial since the Mariner 10 flybys (1974-75). High-resolution images (down to 150 meters per pixel) obtained during the first MESSENGER flyby show evidence for volcanic vents around the Caloris basin inner margin and demonstrate that plains were emplaced sequentially inside and adjacent to numerous large impact craters, to thicknesses in excess of several kilometers. Radial graben and a floor-fractured crater may indicate intrusive activity. These observations, coupled with additional evidence from color images and impact crater size-frequency distributions, support a volcanic origin for several regions of plains and substantiate the important role of volcanism in the geological history of Mercury.     

Effects of relocation on metabolic profiles of freshwater mussels: Metabolomics as a tool for improving conservation techniques

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