Identification of the human homolog of the imprinted mouse Air non-coding RNA

Genomic imprinting is widely conserved amongst placental mammals. Imprinted expression of IGF2R, however, differs between mice and humans. In mice, Igf2r imprinted expression is seen in all fetal and adult tissues. In humans, adult tissues lack IGF2R imprinted expression, but it is found in fetal tissues and Wilms' tumors where it is polymorphic and only seen in a small proportion of tested samples. Mouse Igf2r imprinted expression is controlled by the Air (Airn) ncRNA whose promoter lies in an intronic maternally-methylated CpG island. The human IGF2R gene carries a homologous intronic maternally-methylated CpG island of unknown function. Here, we use transfection and transgenic studies to show that the human IGF2R intronic CpG island is a ncRNA promoter. We also identify the same ncRNA at the endogenous human locus in 16–40% of Wilms' tumors. Thus, the human IGF2R gene shows evolutionary conservation of key features that control imprinted expression in the mouse.     

Anticipating antiport in P-type ATPases

Cation-transporting P-type ATPases show a high degree of structural and functional homology. Nevertheless, for many members of this large family, the molecular mechanism of transport is unclear; namely, whether transport is electrogenic or not and if countertransport is involved remains to be established. In a few well-studied cases such as the Na(+)-K(+)-ATPase, plasma membrane Ca(2+) ATPase (PMCA) and sarcoplasmic reticulum Ca(2+) ATPase (SERCA) countertransport has been clearly demonstrated. New data based on the crystal structure of SERCA now strongly indicate that countertransport could be mandatory for all P-type ATPases. This concept should be verified for other known and for all newly characterized P-type ATPases.     

Viral AlkB proteins repair RNA damage by oxidative demethylation

Bacterial and mammalian AlkB proteins are iron(II)- and 2-oxoglutarate-dependent dioxygenases that reverse methylation damage, such as 1-methyladenine and 3-methylcytosine, in RNA and DNA. An AlkB-domain is encoded by the genome of numerous single-stranded, plant-infecting RNA viruses, the majority of which belong to the Flexiviridae family. Our phylogenetic analysis of AlkB sequences suggests that a single plant virus might have acquired AlkB relatively recently, followed by horizontal dissemination among other viruses via recombination. Here, we describe the first functional characterization of AlkB proteins from three plant viruses. The viral AlkB proteins efficiently reactivated methylated bacteriophage genomes when expressed in Escherichia coli, and also displayed robust, iron(II)- and 2-oxoglutarate-dependent demethylase activity in vitro. Viral AlkB proteins preferred RNA over DNA substrates, and thus represent the first AlkBs with such substrate specificity. Our results suggest a role for viral AlkBs in maintaining the integrity of the viral RNA genome through repair of deleterious methylation damage, and support the notion that AlkB-mediated RNA repair is biologically relevant.     

Cephalopagus conjoined twins in a leopard cat (Prionailurus bengalensis)

Case reports of conjoined twins ("Siamese twins") in wild mammals are scarce. Most published reports of conjoined twins in mammals concern cases in man and domestic mammals. This article describes a case of cephalopagus conjoined twins in a leopard cat (Prionailurus bengalensis) collected on the island of Sumatra, Indonesia, in the period 1873-76. A review of known cases of conjoined twinning in wild mammals is given.     

Comparison of methods for detection of pinworms in mice and rats

Though pinworm infestation remains common in laboratory rodent colonies, there is little information regarding current practices for pinworm detection and their relative efficacy. The authors surveyed research institutions to find out the prevalence of pinworm infestations and the detection methods they used. They also tested mice and rats from colonies that were known to be infested with Syphacia sp. and compared the following detection methods: perianal tape test, fecal flotation, fecal concentration, cecal content examination, cecal flotation and histological examination. Though the different methods yielded comparable efficacy overall, the authors recommend using more than one type of test to increase detection potential.     

UV-B and PAR in single and mixed canopies grown under different UV-B exclusions in the field

The purpose of this study was to investigate whether differences in canopy architecture due to the investigated species (planophile versus erectophile, single versus mixed canopies) or to UV-B effects on plant morphology, lead to differences in UV-B and UV-B/PAR doses within canopies.The development of a very small (10 mm diameter) UV-B and PAR sensor on a long 5 mm wide stick allowed us to measure the penetration of UV-B and PAR in single and mixed canopies of the grass Dactylis glomerata and white clover, Trifolium repens. The plants were grown in greenhouses covered with different thicknesses (3 and 5 mm) of UV-transmittant plexi (12 and 18% UV-B exclusion).For clover, a planophile vegetation, radiation penetration was very low for both UV-B and PAR. UV-B penetration was much less than for PAR, resulting in low UV-B/PAR ratio's within the canopy. This is explained by the low UV-B transmittance of the leaves (<0.1 %) in combination with the planophile leaves.In the grass species, both UV-B and PAR penetrated much deeper into the canopy due to the erectophile structure. The difference between UV-B and PAR penetration was generally quite small except in very tall canopies.The mixed species canopies showed results comparable to the clover canopies. Due to the strongly increased grass growth in these plots, light penetration was generally much lower than in the single species cultures. The increased growth of grass in these mixed plots could be linked to the lower UV-B/PAR dose they received.In plots grown under the higher UV-B level there was a relative decrease in UV-B/PAR ratio within the canopy for both species, compared to canopies from the lower UV-B greenhouses. This could not be explained by changes in leaf angle or biomass, but might be linked to the increase in leaf transmittance of PAR.