Michael Eisenstein

An inner light

In vivo bioluminescence imaging offers a non-invasive look inside the body. Its future looks bright.

Bat research takes wing

In the field and in the lab, scientists across the globe are working to better understand the biology of the bat

An illuminating experience

Philadelphia. considerable interest in porting the optogenetics toolbox to closer evolutionary relatives. Edward Boyden, who helped develop optogenetics with postdoctoral mentor Karl Deisseroth at Stanford University, spearheaded the push to apply the method in nonhuman primates (NHPs) upon starting his own lab at MIT in 2008. A year later, his group published the first study showing that the same techniques that worked in rodents could be translated into macaques1. Progress since then has occurred in fits and starts. “A rodent ranging from eating and sleeping to memory and social behavior, and to dissect the neurological effects of diverse diseases. But more difficult research problems require more sophisticated models, as Azadeh Yazdan learned while researching stroke rehabilitation as a graduate student. “That project failed because it went from rodent models to humans,” says Yazdan, now a neuroengineering researcher at the University of Washington. “They’re good models to study a lot of things, but the cortical anatomy is so different from humans.” Accordingly, there has been The concept of optogenetics sounds almost too good to be true—making direct manipulation of brain activity literally as simple as turning on a light. But scientists have been using laser illumination to selectively activate and deactivate genetically-modified neurons in living rodents for more than a decade now. Armed with this tool, it has become possible to directly link individual brain cell populations and circuits with functions An illuminating experience

Uncovering the roots of pain.

A soy-based diet exacerbates a heart condition in a transgenic mouse model of hypertrophic cardiomyopathy (HCM). These results may have important implications for the interactive relationship between diet and heart disease in humans and the choice of diets fed to animal models used in research. HCM is a relatively common genetic cardiac disorder resulting from a defect in one of several genes; the condition affects as many as 1 in every 500 people. Thickening of the heart muscle characterizes HCM, which results in shortness of breath, chest pain, palpitations, fainting, and in some cases, sudden cardiac death. There is considerable evidence that diets rich in soy provide numerous health benefits, including reduced cancer and cardiovascular risk, probably because of their phytoestrogen content. However, little information is available about the effects of soy consumption on people (and animals) with specific genetic disorders. Leslie A. Leinwand at the University of Colorado at Boulder and her colleagues created a transgenic mouse model of HCM, carrying a mutated α-myosin heavy chain gene. Male HCM mice have enlarged heart muscles that contract poorly, eventually leading to heart failure. Female HCM mice, in contrast, maintain cardiac contractile function and do not develop heart failure. Leinwand’s group proposed that the sexdependent phenotypic characteristics of HCM mice result from exposure to phytoestrogens, which in turn leads to a series of biochemical reactions that culminate in apoptosis of cells in the myocardium. To test this idea, they fed a group of HCM animals a casein-based diet and compared the results to that of mice fed a standard soy-based rodent diet. Although the dietary change showed little effect in females, male mice on the casein diet had improved cardiac function and did not progress to heart failure; indeed, they were almost indistinguishable from wildtype males (J. Clin. Invest., January). The authors speculate that the dramatic sex-related difference in response to the soy diet may arise from the issue that, because “female animals have higher endogenous estrogen levels, the proportional increase in estrogenic compounds via diet is less in females compared with males, who are chronically exposed to significantly lower levels of estrogenic compounds.” Although the present results certainly do not suggest that healthy individuals should shun soy, they do highlight the need to study the interaction of diet and genetics. Likewise, these results underscore the importance of considering diet when characterizing transgenic animal models. Tanja Schub

A conversation with Fernando Nottebohm, PhD

During the last 30 years, a number of revolutionary discoveries in the field of neuroscience have come from what was, at first, an unexpected direction: songbird research. Investigations into seasonal and sex-specific differences in birdsong development have led to important revelations about the impact of sex hormones on brain development and the hormonally controlled plasticity of brain structure, as well as the particularly surprising discovery that neurogenesis continues to occur in the adult brain (see Harding, p. 28). The work of Fernando Nottebohm is widely recognized as having played a key role in bringing these findings to light and thus forcing a general re-examination of established principles of neuroscience.Fernando Nottebohm is Dorothea L. Leonhardt Distinguished Professor at The Rockefeller University, and Director of The Rockefeller Field Research Center for Ethology and Ecology, a 1,200-acre facility located in Millbrook, NY, that provides researchers the opportunity to study behavior and brain function under natural conditions. Nottebohms pioneering work on the neural control of birdsong has led to major discoveries with large impacts in the fields of animal behavior and neuroscience, and has made him one of the founders of neuroethology, the study of how the nervous system controls animal behavior.Nottebohm is a Member of the National Academy of Sciences, USA, and a Fellow of the American Association for the Advancement of Science and of the American Academy of Arts and Sciences. We had a chance to sit down with him to discuss his distinguished career working with laboratory birds.

Best Two Out of Three

Let’s face it—replacement is the most alluring of Russell and Burch’s three Rs. Unfortunately, it also seems to be the least attainable. Indeed, since 1958 when Russell and Burch laid down the framework for the now legally mandated search for alternatives, just a few non-animal alternative tests have been developed and approved. Is this because not enough people are looking for non-animal alternatives? Because there’s not enough funding to inspire the search? Or is it because it’s just not feasible, in most cases, to extract the same information from a petri dish full of cells or a computer simulation as one could obtain from a whole animal? The answer is certainly debatable—and certainly oft debated—but one thing’s for sure: the other two— albeit less sexy—Rs are being attained all around us and may ultimately do more to improve laboratory animal welfare than the simple pursuit of replacement alternatives. The pages of this issue contain four current examples of reduction and refinement alternatives at work. When it comes to reducing the number of animals used in research, the importance of proper experimental design cannot be underestimated. While the use of too many animals in a particular experiment cannot be justified, the use of too few animals may fail to produce statistically significant results. Authors van Wilgenburg, van Schaick Zillesen, and Krulichova (p. 39) describe two computer programs that are meant to guide researchers-in-training on how to properly design an experiment, including how to determine the optimal number of animals. These programs— ExpDesign and Sample Power—are available free-of-charge from the authors. Another group has applied the principles of reduction to toxicity testing. International Organization for Standardization (ISO) guidelines demand that all medical devices undergo testing for cytotoxicity, sensitization, and irritation. The standard test for irritation has traditionally involved injecting three rabbits with a test solution to determine whether chemicals released from device materials may produce skin irritation, as characterized by redness and swelling. Authors Upman, Anderson, and Tasse (p. 26) took a retrospective look at the results of a random sample of 100 dermal toxicity tests and determined that in the vast majority of cases, the same results will be obtained with two rabbits as with three. The concept of refinement is nicely exemplified by the ongoing efforts of the research community to employ environmental enrichment systems to encourage animals’ natural behaviors. While the Animal Welfare Act mandates that nonhuman primates be provided with environmental enrichment devices, relatively little is known about what characteristics make for good choices.After all, what good are such devices if the animals don’t use them or if they actually contribute to an increase in negative behaviors, such as fighting between cage mates? Authors Majolo, Buchanan-Smith, and Bell explore this issue with marmosets, and report their results on p. 32. The move from injectable to inhalation anesthesia represents another success in the field of refinement alternatives, since the latter is generally considered safer and more efficient. It is easy to adjust the anesthetic depth, and because the anesthetics are eliminated from the blood by exhalation, with less reliance on drug metabolism to remove the drug from the body, there is less chance for drug-induced toxicity. The use of inhalation agents requires specialized equipment for delivery, and so author Diven (p. 44) provides an overview of commonly used agents and equipment.