Plasticity of thermal tolerance and its relationship with growth rate in juvenile mussels (Mytilus californianus)

Complex life cycles characterized by uncertainty at transitions between larval/juvenile and adult environments could favour irreversible physiological plasticity at such transitions. To assess whether thermal tolerance of intertidal mussels (Mytilus californianus) adjusts to post-settlement environmental conditions, we collected juveniles from their thermally buffered microhabitat from high- and low-shore locations at cool (wave-exposed) and warm (wave-protected) sites. Juveniles were transplanted to unsheltered cages at the two low sites or placed in a common garden. Juveniles transplanted to the warm site for one month in summer had higher thermal tolerance, regardless of origin site. By contrast, common-garden juveniles from all sites had lower tolerance indistinguishable from exposed site transplants. After six months in the field plus a common garden period, there was a trend for higher thermal tolerance at the protected site, while reduced thermal tolerance at both sites indicated seasonal acclimatization. Thermal tolerance and growth rate were inversely related after one but not six months; protected-site transplants were more tolerant but grew more slowly. In contrast to juveniles, adults from low-shore exposed and protected sites retained differences in thermal tolerance after common garden treatment in summer. Both irreversible and reversible forms of plasticity must be considered in organismal responses to changing environments.

Improvement of Ulcerations in Treatment-Resistant Chronic Scarring in a Patient with Pyoderma Gangrenosum After Improving Vascular Insufficiency, Gently Removing Necrotic Debris, and Decreasing Wound Fluid

BACKGROUND Classical pyoderma gangrenosum is a rare, inflammatory, neutrophilic dermatosis that commonly presents with severe ulcerations on the lower extremities and is often misdiagnosed and mistreated. Delay in treatments can lead to worsening of the ulcerations and allows for multiple comorbid factors. Pyoderma gangrenosum is most commonly treated with immunosuppressants or anti-inflammatory agents and is often worsened by surgical procedures due to the presence of pathergy. In acute cases, a course of anti-inflammatory treatments works well in alleviating symptoms and reducing ulcerations and residual scarring. However, in chronic cases with the presence of severe scarring and necrotic ulcerations, the simple implementation of systemic immunosuppressants is frequently ineffective alone. Although not mentioned in most case reports on pyoderma gangrenosum, the chronicity of its inflammatory component can lead to necrosis and scarring and subsequent vascular insufficiency. CASE REPORT We present a severe case of chronic ulcerative pyoderma gangrenosum in a patient who had treatment-resistant ulcerations and cribriform edematous scarring with subsequent vascular insufficiency of the right lower extremity. This patient, while receiving topical clobetasol, had marked improvement in the healing of his ulcerations only after starting a novel course of cadexomer iodine, compression stockings, and pentoxifylline. CONCLUSIONS The efficacy of non-anti-inflammatory treatments indicates that chronic pyoderma gangrenosum with extensive scarring is commonly associated with the comorbid factors of vascular insufficiency, necrotic debris, and extensive wound fluid. In cases of ulcerations in chronic pyoderma gangrenosum that are resistant to anti-inflammatory treatments alone, one should identify and address other compounding factors that may inhibit wound healing.