Looking within for vision

Channelrhodopsin-2 (ChR2), a directly light-gated cation channel from the green alga Chlamydomonas reinhardtii has been shown to be a directly light-switched cation-selective ion channel, which employs 11-cis retinal as its chromophore. This is the same chromophore as the mammalian photoreceptor's visual pigment-rhodopsin. Previously, investigators demonstrated that ChR2 can be used to optically control neuronal firing by depolarizing the cell. In this issue of Neuron, Bi et al. apply viral-mediated gene transfer to deliver ChR2 to retinal ganglion cells (RGC) in a rodent model of inherited blindness. In this way, the authors have genetically engineered surviving retinal neurons to take on the lost photoreceptive function. The conversion of light-insensitive retinal interneurons into photosensitive cells introduces an entirely new direction for treatments of blinding retinal degeneration.     

Looking for immigration law

Culling the Masses by Professors David Scott FitzGerald and David Cook-Martín is an impressive work that makes important scholarly contributions. It analyses the trend in the USA, Canada, Cuba, Mexico, Brazil and Argentina away from explicit racial discrimination in immigration laws. One layer of the book's argument examines how ‘vertical’ (domestic) and ‘horizontal’ (external) forces led these countries to abandon explicit racism. In another layer, the book argues that this anti-racist turn was not a product of democracy. Instead, racist immigration laws were often the product of democratic influences and institutions. The nuanced examination of external influences on national immigration laws in Culling the Masses is an invaluable contribution. However, its inconsistent definition of ‘immigration law’ across countries leaves incomplete both its assessment of racism in the present-day immigration laws, and in turn, its assessment of the relationship between democracy and racism.     

Looking for syringyl peroxidases

Lignins are cell wall heteropolymers that arise from the peroxidase-mediated coupling of p-coumaryl, coniferyl and sinapyl alcohols. In gymnosperms, they are derived from coniferyl alcohol, whereas in angiosperms, lignins are derived from coniferyl and sinapyl alcohols. Thus, although it is frequently assumed that the chemical complexity of lignins has increased during plant evolution, it is frequently forgotten that pteridophytes have lignins that are derived from sinapyl alcohol. Until recently, most peroxidases characterized in flowering plants only oxidized coniferyl alcohol. However, recent reports have described the molecular characterization of peroxidases capable of oxidizing sinapyl alcohol (syringyl peroxidases). Current molecular studies propose that the structural motifs of syringyl peroxidases predate the radiation of tracheophytes, which suggests that syringyl peroxidases existed before the appearance of syringyl lignins.     

Looking for a 5-HT7 radiotracer for positron emission tomography

In search of a serotonin 5-HT₇ radiotracer for positron emission tomography, we developed 1-{2-[(2S)-1-(phenylsulfonyl)pyrrolidin-2-yl]ethyl}piperidin-4-yl 4-fluorobenzoate. After labeling in good yield with fluorine-18 via nitro for fluorine exchange, preliminary biological experiments with autoradiographies failed to evidence any specific 5-HT₇ receptor delineation.     

寻找黑脸琵鹭觅食地

黑脸琵鹭的觅食地在哪里?民以食为天,鸟为食而亡。弄清黑脸琵鹭的食物来源,对保护它们至关重要。     

Looking for alternative energy sources

With unrest in oil-exporting countries, backlashes against biofuels and photovoltaics, and a nuclear incident in Japan, the year 2011 rattled confidence in future energy supplies. The search for alternatives is all the more urgent, but some of the solutions investigated hark back to fossil fuels that we can't afford to burn.     

Looking for trouble: a search for developmental defects of the hypothalamus

The hypothalamus is a critical integrator of several homeostatic processes that are required for the survival of vertebrates. Disruption of the development of the hypothalamus thus has the potential of perturbing important physiological processes with lifelong consequences. We review current knowledge about how cell types are specified and circuits are formed within the developing hypothalamus. We emphasize the potential clinical impact of the perturbations of these pathways using the regulation of energy balance as a model. We predict that disruption of hypothalamic development is a common, previously unsuspected cause of disorders of homeostatic processes such as obesity and high blood pressure.     

Looking for compensation at multiple scales in a wetland bird community

Compensatory dynamics, during which community composition shifts despite a near‐constant total community size, are usually rare: Synchronous dynamics prevail in natural communities. This is a puzzle for ecologists, because of the key role of compensation in explaining the relation between biodiversity and ecosystem functioning. However, most studies so far have considered compensation in either plants or planktonic organisms, so that evidence for the generality of such synchrony is limited. Here, we extend analyses of community‐level synchrony to wetland birds. We analyze a 35‐year monthly survey of a community where we suspected that compensation might occur due to potential competition and changes in water levels, favoring birds with different habitat preferences. We perform both year‐to‐year analyses by season, using a compensation/synchrony index, and multiscale analyses using a wavelet‐based measure, which allows for both scale‐ and time‐dependence. We analyze synchrony both within and between guilds, with guilds defined either as tightknit phylogenetic groups or as larger functional groups. We find that abundance and biomass compensation are rare, likely due to the synchronizing influence of climate (and other drivers) on birds, even after considering several temporal scales of covariation (during either cold or warm seasons, above or below the annual scale). Negative covariation in abundance at the guild or community level did only appear at the scale of a few months or several years. We also found that synchrony varies with taxonomic and functional scale: The rare cases where compensation appeared consistently in year‐to‐year analyses were between rather than within functional groups. Our results suggest that abundance compensation may have more potential to emerge between broad functional groups rather than between species, and at relatively long temporal scales (multiple years for vertebrates), above that of the dominant synchronizing driver.     

Looking for the Primordial Genetic Honeycomb

All life forms on Earth share the same biological program based on the DNA/RNA genomes and proteins. The genetic information, recorded in the nucleotide sequence of the DNA and RNA molecule, supplies the language of life which is transferred through the different generations, thus ensuring the perpetuation of genetic information on Earth. The presence of a genetic system is absolutely essential to life. Thus, the appearance in an ancestral era of a nucleic acid-like polymer able to undergo Darwinian evolution indicates the beginning of life on our planet. The building of primordial genetic molecules, whatever they were, required the presence of a protected environment, allowing the synthesis and concentration of precursors (nucleotides), their joining into larger molecules (polynucleotides), the protection of forming polymers against degradation (i.e. by cosmic and UV radiation), thus ensuring their persistence in a changing environment, and the expression of the “biological” potential of the molecule (its capacity to self-replicate and evolve). Determining how these steps occurred and how the primordial genetic molecules originated on Earth is a very difficult problem that still must be resolved. It has long been proposed that surface chemistry, i.e. on clay minerals, could have played a crucial role in the prebiotic formation of molecules basic to life. In the present work, we discuss results obtained in different fields that strengthen the hypothesis of a clay-surface-mediated origin of genetic material. Presented at: National Workshop on Astrobiology: Search for Life in the Solar System, Capri, Italy, 26 to 28 October, 2005.