Parental investment by skin feeding in a caecilian amphibian

Although the initial growth and development of most multicellular animals depends on the provision of yolk, there are many varied contrivances by which animals provide additional or alternative investment in their offspring. Providing offspring with additional nutrition should be favoured by natural selection when the consequent increased fitness of the young offsets any corresponding reduction in fecundity. Alternative forms of nutrition may allow parents to delay and potentially redirect their investment. Here we report a remarkable form of parental care and mechanism of parent-offspring nutrient transfer in a caecilian amphibian. Boulengerula taitanus is a direct-developing, oviparous caecilian, the skin of which is transformed in brooding females to provide a rich supply of nutrients for the developing offspring. Young animals are equipped with a specialized dentition, which they use to peel and eat the outer layer of their mother's modified skin. This new form of parental care provides a plausible intermediate stage in the evolution of viviparity in caecilians. At independence, offspring of viviparous and of oviparous dermatotrophic caecilians are relatively large despite being provided with relatively little yolk. The specialized dentition of skin-feeding (dermatophagous) caecilians may constitute a preadaptation to the fetal feeding on the oviduct lining of viviparous caecilians.     

G1-phase progression in pluripotent stem cells

Cellular and Molecular Life Sciences - During early embryonic development both the rapid increase in cell number and the expression of genes that control developmental decisions are tightly...     

Analysis of the Plasmodium falciparum proteome by high-accuracy mass spectrometry

The annotated genomes of organisms define a 'blueprint' of their possible gene products. Post-genome analyses attempt to confirm and modify the annotation and impose a sense of the spatial, temporal and developmental usage of genetic information by the organism. Here we describe a large-scale, high-accuracy (average deviation less than 0.02 Da at 1,000 Da) mass spectrometric proteome analysis of selected stages of the human malaria parasite Plasmodium falciparum. The analysis revealed 1,289 proteins of which 714 proteins were identified in asexual blood stages, 931 in gametocytes and 645 in gametes. The last two groups provide insights into the biology of the sexual stages of the parasite, and include conserved, stage-specific, secreted and membrane-associated proteins. A subset of these proteins contain domains that indicate a role in cell-cell interactions, and therefore can be evaluated as potential components of a malaria vaccine formulation. We also report a set of peptides with significant matches in the parasite genome but not in the protein set predicted by computational methods.     

The callipyge mutation enhances the expression of coregulated imprinted genes in cis without affecting their imprinting status

The callipyge (CLPG) phenotype (from kappa(alpha)lambda(iota), "beautiful," and pi(iota)gamma(epsilon), "buttocks") described in sheep is an inherited muscular hypertrophy that is subject to an unusual parent-of-origin effect referred to as polar overdominance: only heterozygous individuals having inherited the CLPG mutation from their sire exhibit the muscular hypertrophy. The callipyge (clpg) locus was mapped to a chromosome segment of approximately 400 kb (refs. 2-4), which was shown to contain four genes (DLK1, GTL2, PEG11 and MEG8) that are preferentially expressed in skeletal muscle and subject to parental imprinting in this tissue. Here we describe the effect of the CLPG mutation on the expression of these four genes, and demonstrate that callipyge individuals have a unique expression profile that may account for the observed polar overdominance.     

Active control of slow light on a chip with photonic crystal waveguides

It is known that light can be slowed down in dispersive materials near resonances. Dramatic reduction of the light group velocity-and even bringing light pulses to a complete halt-has been demonstrated recently in various atomic and solid state systems, where the material absorption is cancelled via quantum optical coherent effects. Exploitation of slow light phenomena has potential for applications ranging from all-optical storage to all-optical switching. Existing schemes, however, are restricted to the narrow frequency range of the material resonance, which limits the operation frequency, maximum data rate and storage capacity. Moreover, the implementation of external lasers, low pressures and/or low temperatures prevents miniaturization and hinders practical applications. Here we experimentally demonstrate an over 300-fold reduction of the group velocity on a silicon chip via an ultra-compact photonic integrated circuit using low-loss silicon photonic crystal waveguides that can support an optical mode with a submicrometre cross-section. In addition, we show fast (approximately 100 ns) and efficient (2 mW electric power) active control of the group velocity by localized heating of the photonic crystal waveguide with an integrated micro-heater.     

A fast low-power optical memory based on coupled micro-ring lasers

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 x 40 microm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20 ps with 5.5 fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.     

The worldwide leaf economics spectrum

Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.     

Additional new species of Grouvellinus Champion 1923 (Insecta,Coleoptera, Elmidae) discovered by citizen scientists and DNA barcoded in the field applying a novel MinION-based workflow

ABSTRACT

Four new species, Grouvellinus nigerquadratus sp. nov., G. cruxniger sp. nov., G. luciaensis sp. nov., and G. borneensis sp. nov., are described from Borneo and illustrated in detail. Two additional species of the genus which remain undescribed are briefly diagnosed. The material was collected during Taxon Expeditions’ field course which involved citizen scientists, students and taxonomists. Specimens were collected at altitudes between 270 m and 750 m above sea level using fine-meshed hand-nets and blacklight traps. The morphological species delimitation based on morphology was supplemented and congruent with mtDNA sequences which are the first DNA barcodes for the genus from Borneo. They were obtained in the field using a newly developed rapid and accurate MinION-based workflow. The inter – and intraspecific genetic distances and the problems regarding cryptic species delimitation are discussed.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:4B1D0F3D-B303-46A5-86B4-C23454192327     

刚果盆地的棘管轮属(轮虫门;单巢亚纲;棘管轮科)

研究了2010年4月到5月和2012年6月二次采集自刚果盆地的水样,共发现棘管轮属Mytilina Bory de St.Vincent 1826的8个种,其中2个种 M.crassipes (Lucks,1912) 和 M.trigona (Gosse,1851)是非洲新纪录种; M.macrocera (Jennings,1894)和 M.bisulcata (Lucks,1912)是刚果盆地多个样点的常见种;M.ventralis (Ehrenberg,1830)和M.trigona,在刚果盆地个别样点比较多见;M.michelangllii Reid & Turner,1988, M.crassipes和M. brevispina (Ehrenberg,1830)在此次刚果盆地的调查中非常罕见;描述了一种棘管轮,其形态奇特,可能是新种.