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Although island attributes such as size and accessibility to colonizing organisms can influence community structure, the consequences of these for ecosystem functioning are little understood. A study of the suspended soils of spatially discrete epiphytes or treetop “islands” in the canopies of New Zealand rainforest trees revealed that different components of the decomposer community responded either positively or negatively to island size, as well as to the tree species that the islands occurred in. This in turn led to important differences between islands in the rates of ecosystem processes driven by the decomposer biota. This system serves as a model for better understanding how attributes of both real and habitat islands may affect key ecosystem functions through determining the community structure of organisms that drive these functions.

Higher order chromatin structure presents a barrier to the recognition and repair of DNA damage. Double-strand breaks (DSBs) induce histone H2AX phosphorylation, which is associated with the recruitment of repair factors to damaged DNA. To help clarify the physiological role of H2AX, we targeted H2AX in mice. Although H2AX is not essential for irradiation-induced cell-cycle checkpoints, H2AX−/−mice were radiation sensitive, growth retarded, and immune deficient, and mutant males were infertile. These pleiotropic phenotypes were associated with chromosomal instability, repair defects, and impaired recruitment of Nbs1, 53bp1, and Brca1, but not Rad51, to irradiation-induced foci. Thus, H2AX is critical for facilitating the assembly of specific DNA-repair complexes on damaged DNA.

During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

Laser capture microdissection (LCM) under direct microscopic visualization permits rapid one-step procurement of selected human cell populations from a section of complex, heterogeneous tissue. In this technique, a transparent thermoplastic film (ethylene vinyl acetate polymer) is applied to the surface of the tissue section on a standard glass histopathology slide; a carbon dioxide laser pulse then specifically activates the film above the cells of interest. Strong focal adhesion allows selective procurement of the targeted cells. Multiple examples of LCM transfer and tissue analysis, including polymerase chain reaction amplification of DNA and RNA, and enzyme recovery from transferred tissue are demonstrated.

Genetic disorders affecting cellular responses to DNA damage are characterized by high rates of translocations involving antigen receptor loci and increased susceptibility to lymphoid malignancies. We report that the Nijmegen breakage syndrome protein (NBS1) and histone γ-H2AX, which associate with irradiation-induced DNA double-strand breaks (DSBs), are also found at sites of V(D)J (variable, diversity, joining) recombination–induced DSBs. In developing thymocytes, NBS1 and γ-H2AX form nuclear foci that colocalize with the T cell receptor α locus in response to recombination activating gene (RAG) protein–mediated V(D)J cleavage. Our results suggest that surveillance of T cell receptor recombination intermediates by NBS1 and γ-H2AX may be important for preventing oncogenic translocations.

What would be the advantage of unicellular organisms becoming multicellular? For organisms that feed on organic food (heterotrophs), the most efficient way to produce energy is to metabolize the food by aerobic respiration, but the fastest way is to metabolize it by fermentation. In their Perspective, Cox and Bonner discuss a mathematical model (Pfeiffer et al.), which shows that when these two kinds of organisms (respirators and fermenters) compete for a limited food source, the respirators manage best when they are grouped in clusters rather than remaining as separate cells. In this way, multicellularity could have originated.

As J. Handelsman et al. note in their Policy Forum “Scientific teaching” (23 Apr., p. [521][1]), recent educational research has shown that a variety of active-learning strategies are superior to the teaching methods that many of us experienced in our own training. That is, the traditional approach of lecturing to a room full of students seems to be less effective than engaging these students in the process of thinking about the information. A particular challenge, which was not noted by Handlesman et al. , is reorienting our role in the training of secondary science teachers—indeed, in training teachers throughout the K-12 enterprise. In general, the science courses through which K-12 teachers learn their science are taught by scientists. It is incumbent upon us as scientists to ask ourselves how well we serve as role models for the teachers we train. In general, we tend to teach the way we were taught ourselves. It is only after we become more comfortable with our teaching expertise, and more comfortable in our other roles as scientists, that some of us may begin to investigate alternate pedagogical approaches. The same can be said for the students whom we teach. If we instruct our future K-12 teachers by the traditional approach of lecturing about scientific facts, we may expect that they will use the same methods in their own classes. But science is not the memorization of facts. It is an ongoing, investigative endeavor. It requires thinking deeply about subjects, and continuously assessing whether the data support the current understanding. Actually doing science requires a world view that is quite different from that which we portray in our classes. As scientific literacy has declined, we have considered a variety of ways to address it. One very important effort has been the development of the National Science Education Standards ([1][2], [2][3]). Built into the Standards is the expectation that the teaching of science should be realigned to match more closely the doing of science. That is, K-12 instruction should, wherever possible, use methods of active learning and of inquiry-based learning. The typical response to reading this, I suspect, will be “good, that is as it should be.” Thus, we have a paradox. We applaud the Standards' exhortation to teach science as an investigative endeavor and to use inquiry-based methods where possible. Yet, we, ourselves, tend to teach the way we were taught and use didactic lecturing—through which we train future K-12 teachers the avoidance of inquiry-based methods. Consequently, it is exceedingly difficult for K-12 teachers to incorporate inquiry-based teaching into their courses. This realization suggests that it is essential that we move our own teaching methods into the current century, pay attention to the educational literature, and use active learning, problem-based learning, and inquiry-based learning in our own classes. Handelsman et al. have offered recommendations for how we might improve the Culture of Science to put greater weight on the teaching enterprise. I suspect, however, given the vast inertia of our scientific and educational systems, that a single Policy Forum will be insufficient. It will be necessary to give educational innovations the same degree of attention that we give to basic research. Given the prestige and wide readership of Science , I ask that a new section of the journal be created to discuss teaching issues. We need open and frequent discussion of this tremendously important issue. 1. 1.[↵][4] 1. National Research Council , National Science Education Standards (National Academy Press, Washington, DC, 1996). 2. 2.[↵][5] 1. National Research Council , Inquiry and the National Science Education Standards: A Guide for Teaching and Learning (National Academy Press, Washington, DC, 2000). [1]: /lookup/doi/10.1126/science.1096022 [2]: #ref-1 [3]: #ref-2 [4]: #xref-ref-1-1 "View reference 1. in text" [5]: #xref-ref-2-1 "View reference 2. in text"

Genomic instability is a hallmark of cancer and is featured prominently in Bloom syndrome. Bloom syndrome, the prototype of somatic mutational disorders, is a rare autosomal recessive disorder characterized by a profound predisposition to cancer. Bloom syndrome is caused by inactivating, germline