Population Structure in the Roundtail Chub (Gila robusta Complex) of the Gila River Basin as Determined by Microsatellites: Evolutionary and Conservation Implications.

Ten microsatellite loci were characterized for 34 locations from roundtail chub (Gila robusta complex) to better resolve patterns of genetic variation among local populations in the lower Colorado River basin. This group has had a complex taxonomic history and previous molecular analyses failed to identify species diagnostic molecular markers. Our results supported previous molecular studies based on allozymes and DNA sequences, which found that most genetic variance was explained by differences among local populations. Samples from most localities were so divergent species-level diagnostic markers were not found. Some geographic samples were discordant with current taxonomy due to admixture or misidentification; therefore, additional morphological studies are necessary. Differences in spatial genetic structure were consistent with differences in connectivity of stream habitats, with the typically mainstem species, G. robusta, exhibiting greater genetic connectedness within the Gila River drainage. No species exhibited strong isolation by distance over the entire stream network, but the two species typically found in headwaters, G. nigra and G. intermedia, exhibited greater than expected genetic similarity between geographically proximate populations, and usually clustered with individuals from the same geographic location and/or sub-basin. These results highlight the significance of microevolutionary processes and importance of maintaining local populations to maximize evolutionary potential for this complex. Augmentation stocking as a conservation management strategy should only occur under extreme circumstances, and potential source populations should be geographically proximate stocks of the same species, especially for the headwater forms.

Primary benign interatrial schwannoma encountered during aortic valve replacement.

Primary neurogenic tumors of the heart are extremely uncommon. We report the resection of a benign primary schwannoma of the right atrium found incidentally during an aortic valve replacement.

The role of cytoprotective cytokines in cardiac ischemia/reperfusion injury.

The mechanism(s) underlying the beneficial effects of adult mesenchymal stem cells (MSCs) after myocardial infarction (MI) is poorly understood. One possible explanation is the ability of MSCs to secrete cytokines, which modulate cardiomyocyte survival and function. MSCs express at least two cytoprotective cytokines, hepatocyte growth factor (HGF) and stromal cell-derived factor-1 alpha (CXCL12). The aim of our study was to compare the effects of these two cytokines administered acutely post-MI. We subjected adult male Lewis rats to myocardial ischemia/reperfusion injury. Immediately upon reperfusion, polymers saturated with HGF or CXCL12 were placed onto the infarcted anterior wall and the rats were allowed to recover. Echocardiographic analysis at 4 wk post-MI to assess left ventricular (LV) function revealed that LV ejection fraction was increased in the HGF treated group compared with the phosphate-buffered saline (PBS) control group. Likewise, LV end diastolic dimension was reduced in the HGF treated group compared with the PBS control group. Similarly, invasive hemodynamics at 12 wk showed improved contractility and relaxation in the HGF treated group compared with the PBS control group. In contrast, no significant effect on LV function was seen in the CXCL12 treated group. To determine the potential mechanism for this effect, infarct size (IFS) at 72 h was determined. IFS was decreased 4.2-fold in the HGF treated group compared with the PBS control group. Thus, HGF acutely post-MI using polymer delivery reduces IFS, leading to beneficial effects on post-MI LV remodeling.