This issue's Immunology Select highlights recent studies that provide insight into the timing and regulation of both innate and adaptive immune responses. Recent work in the fruit fly shows that enhanced stem cell proliferation in the intestine maintains tissue homeostasis in the face of bacterial infection. Other recent findings include a new factor involved in regulatory T cell function, a ro...

Several recent studies use microscopy, mass spectroscopy, and proteomic analysis of B cells to elucidate the rapid changes that occur when the B cell receptor engages with its antigen. Other new findings call attention to the emerging role of Toll-like receptors in B cell-mediated autoimmunity. Here we discuss these studies and what they reveal about the intriguing biology of B cells. B cells a...

T helper 17 (Th17) cells are a recently discovered lineage of T lymphocytes that have been implicated in auto-immunity and inflammation. Several recent studies reveal new factors that promote or impair differentiation of T lymphocytes into Th17 cells, thereby contributing to our understanding of how this lineage is specified and how to combat Th17-mediated autoimmunity. Differentiation of naı¨v...

This issue's Neurobiology Select highlights different molecular aspects of the patterning of neuronal circuits during development, as well as factors that determine the number of neurons in the circuit. The network of neu-ronal dendrites receives synaptic input often through specialized structures called spines, and we highlight some recent insights into how these structures are formed. We also...

Frontotemporal dementia (FTD) has been linked to mutations in the gene on chromosome 17 that encodes the microtubule-associated protein tau. However, not all patients with FTD have tau mutations even though their disease has been genetically linked to chromosome 17. Such patients exhibit an unusual pathology with ubiquitinimmunoreactive nuclear and cytoplasmic inclusions in layer II of the fron...

The dopaminergic neurons of the central nervous system regulate behavior associated with reward and punishment. Loss of dopamine neurons in the substantia nigra leads to Parkinson’s disease. This issue’s Neurobiology Select discusses the discovery of a neural circuit involved in decision making in flies and a report showing that associative learning shifts the timing of dopamine signaling in ro...

1997 The following supplement to the original (1997) field guide is available:

This article introduces the web-based learning environment SQLearn, which allows learners to receive automated, individual feedback on the SQL queries. The SQLearn system performs a syntax check as well as a check of the semantic and structure of the formulated SQL query. To give feedback about semantic errors, the parse tree of the SQL query is compared with the parse trees of the sample solut...