Medicine. DNA arrays reveal cancer in its many forms

The use of microarrays--slides or chips systematically dotted with DNA from thousands of genes--to determine gene expression patterns is providing a wealth of new information that should aid in cancer diagnosis and ultimately in therapy. In the past several months, researchers in several labs have used microarray technology to identify specific subtypes of a variety of cancers, including leukemias and lymphomas, the dangerous skin cancer melanoma, and breast cancer. In some cases, they can determine which cancers are likely to respond to current therapies and which aren't. In addition, the studies are giving researchers a fix on which genes are important for the development, maintenance, and spread of the various cancers, and are thus possible drug targets.     

Roles of NPM2 in chromatin and nucleolar organization in oocytes and embryos

Upon fertilization, remodeling of condensed maternal and paternal gamete DNA occurs to form the diploid genome. In Xenopus laevis, nucleoplasmin 2 (NPM2) decondenses sperm DNA in vitro. To study chromatin remodeling in vivo, we isolated mammalian NPM2 orthologs. Mouse NPM2 accumulates in oocyte nuclei and persists in preimplantation embryos. Npm2 knockout females have fertility defects owing to failed preimplantation embryo development. Although sperm DNA decondensation proceeds without NPM2, abnormalities are evident in oocyte and early embryonic nuclei. These defects include an absence of coalesced nucleolar structures and loss of heterochromatin and deacetylated histone H3 that normally circumscribe nucleoli in oocytes and early embryos, respectively. Thus, Npm2 is a maternal effect gene critical for nuclear and nucleolar organization and embryonic development.     

Receptive field organization of the S-potential

The receptive fields of S-potentials have been studied in carp retinas. The relationship between the stimulus intensity and area of stimulation was examined for each component of three different types of S-potential. It appears that for each component there is full summation over a large portion of the retina, a type of organization different from that found in the ganglion cell.     

Territorial organization of the lowland classic maya

Thus far I have discussed ancient Maya sociopolitical structure from the upper levels of the hierarchy downward. Let me now summarize their territorial organization from the bottom upward, starting at the hamlet level (Fig. 8). The smallest unit of settlement-one usually overlooked by archeological surveys in the lowland rain forest-was probably a cluster of thatched huts occupied by a group of related families; larger clusters may have been divided into four quadrants along the lines suggested by Coe (26). Because of the long fallow period (6 to 8 years) characteristic of slash-and-burn agriculture in the Petén, these small hamlets are presumed to have changed location over the years, although they probably shifted in a somewhat circular fashion around a tertiary ceremonial-civic center for whose maintenance they were partly responsible. These tertiary centers were spaced at fairly regular intervals around secondary ceremonial-civic centers with pyramids, carved monuments, and palace-like residences. In turn, the secondary centers occurred at such regular intervals as to form hexagonal patterns around primary centers, which were still larger, with acropolises, multiple ceremonial plazas, and greater numbers of monuments. In some cases, the distance between secondary centers was roughly twice the distance between secondary and tertiary centers, creating a lattice of nested hexagonal cells. This pattern, which conforms to a Western theoretical construct, was presumably caused by factors of service function, travel, and transport. The pattern was not recognized by the Maya at all. They simply recognized that a whole series of smaller centers were dependent on a primary center and therefore mentioned its emblem glyph. Linking the centers of the various hexagons were marriage alliances between members of royal dynasties, who had no kinship ties with the farmers in the hamlets. Out of the large number of primary centers available to them, the Maya selected four as regional capitals. True to their cosmology, the Maya regarded these capitals as associated with the four quadrants of their realm, regardless of their actual location. Each was the home city for a very important dynasty whose junior members probably ruled secondary centers. Since the hexagonal lattices were probably adjusted to variations in population density, each of the four quadrants of the Maya realm probably controlled a comparable number of persons. So strong was the cognized model that, despite the rise and fall of individual centers, there seem always to have been four capitals, each associated with a direction and, presumably, with a color. There is still a great deal to learn about the social, political, and territorial organization of the lowland Maya, and parts of the picture presented here need far more data for their confirmation. What seems likely is that the Maya had an overall quadripartite organization (rather than a core and buffer zone) and that within each quadrant there was at least a five-tiered administrative hierarchy of capital, secondary center, tertiary center, village, and hamlet. Perhaps most significant, there was no real conflict between the lattice-like network predicted by locational analysis and the cosmological four-part structure predicted by epigraphy and ethnology.     

Aging, chromatin, and food restriction--connecting the dots

Model organisms such as yeast have proved exceptionally valuable for revealing new information about the molecular pathways involved in the aging of cells. In her Perspective, Campisi comments on new work showing that caloric restriction increases longevity in yeast by activating the SIR2 gene, which alters the compactness of chromatin and thus regulates gene expression (Lin et al.).     

Field experiments with transformed plants reveal the sense of floral scents

Plants use many means to attract pollinators, including visual cues and odor. We investigated how nonpigment floral chemistry influences nectar removal, floral visitation, florivory, rates of outcrossing, and fitness through both male and female functions. We blocked expression of biosynthetic genes of the dominant floral attractant [benzyl acetone (Nachal1)] and nectar repellent [nicotine (Napmt1/2)] in all combinations in the native tobacco Nicotiana attenuata and measured their effects on plants in their native habitat. Both repellent and attractant were required to maximize capsule production and seed siring in emasculated flowers and flower visitation by native pollinators, whereas nicotine reduced florivory and nectar robbing.     

Incidence of sex chromatin in Gallus domesticus

The presence of so-called sex chromatin has been demonstrated in the interphase nuclei of the cells of the domestic chicken (Gallus domesticus). Definite sex dimorphism was observed for the incidence of this nuclear component; the frequency of its occurrence in females was at least ten times that of its occurrence in the males, ranging from 22 percent in the duodenal muscle cells to 52 percent in the epidermal cells of a growing feather.     

Development of the place principle: tonotopic organization

The tonotopic organization of brainstem auditory nuclei was compared in embryonic and hatchling chickens. In embryos, neurons at any given position in these nuclei were maximally sensitive to lower frequency sounds than the best frequency after hatching. This finding indicates that neurons are maximally stimulated by sounds of different frequencies as development proceeds and supports the hypothesis that during development there is a change in the spatial encoding of frequency along the cochlea.     

论以人为本的学生组织文化建设

依据大学自治、学术自由和人文主义精神传统,界定了以人为本的学生组织文化的内涵和特征,从学生导向、学习导向、＂竞＂＂合＂导向、创新导向、团队导向、自治导向等6个方面确立了以人为本的学生组织文化建设的纬度,探索了以人为本的学生组织文化建设的途径。     

浅论学习型组织与行政文化创新

知识经济的到来,对政府组织的建设提出了新的要求。行政文化作为政府组织的内环境是关键的环节,对于推进政府组织的变革有着重要的作用。文章着力探讨学习型组织理念对于行政文化创新的影响,力图摒弃政府组织中个别的”官僚文化”的气息,提出以创新的精神重塑政府文化环境的观点。     

Social organization in the bat Myotis adversus

Studies in which the Australian bat Myotis adversus was marked and recaptured showed that mature males tend to be solitary, are strongly attached to a particular site, and apparently defend home sites. Harem formation concurrent with mating has been observed, and the bond between the mother and her young extends beyond extends beyond nursing.