Functional equivalence classes in rats: Repeated olfactory discrimination reversals and delayed stimulus probes.

The simultaneous matching-to-sample procedures that are widely used to study stimulus equivalence in human participants have generally been unsuccessful in animals. However, functional equivalence classes have been demonstrated in pigeons and sea lions using a concurrent repeated reversal discrimination procedure. In this procedure, responding to one set of stimuli is reinforced but responding to a different set is not and the set associated with reinforcement is changed with multiple reversals during the experiment.

Diffuse encephalitic toxoplasmosis in HIV.

This case demonstrates an atypical radiological presentation of cerebral toxoplasmosis in a 62-year-old HIV-positive patient. The diagnosis is discussed alongside MRI imaging, laboratory results and treatment. Central nervous system toxoplasmosis is typically associated with ring enhancing lesions on neuroimaging with contrast, but the radiology for this patient shows diffuse white matter changes and ependymal enhancement, which would normally suggest an alternative diagnosis.

Three acyltransferases and nitrogen-responsive regulator are implicated in nitrogen starvation-induced triacylglycerol accumulation in Chlamydomonas.

Algae have recently gained attention as a potential source for biodiesel; however, much is still unknown about the biological triggers that cause the production of triacylglycerols. We used RNA-Seq as a tool for discovering genes responsible for triacylglycerol (TAG) production in Chlamydomonas and for the regulatory components that activate the pathway. Three genes encoding acyltransferases, DGAT1, DGTT1, and PDAT1, are induced by nitrogen starvation and are likely to have a role in TAG accumulation based on their patterns of expression.

TAG, you're it! Chlamydomonas as a reference organism for understanding algal triacylglycerol accumulation.

Photosynthetic organisms are responsible for converting sunlight into organic matter, and they are therefore seen as a resource for the renewable fuel industry. Ethanol and esterified fatty acids (biodiesel) are the most common fuel products derived from these photosynthetic organisms. The potential of algae as producers of biodiesel precursor (or triacylglycerols (TAGs)) has yet to be realized because of the limited knowledge of the underlying biochemistry, cell biology and genetics.