Organotypic culture of adult rabbit retina

Organotypic culture systems of functional neural tissues are important tools in neurobiological research. Ideally, such a system should be compatible with imaging techniques, genetic manipulation, and electrophysiological recording. Here we present a simple interphase tissue culture system for adult rabbit retina that requires no specialized equipment and very little maintenance. We demonstrate the dissection and incubation of rabbit retina and particle-mediated gene transfer of plasmids encoding GFP or a variety of subcellular markers into retinal ganglion cells. Rabbit retinas cultured this way can be kept alive for up to 6 days with very little changes of the overall anatomical structure or the morphology of individual ganglion- and amacrine cells.     

Seasonal Variations in the Structure of an Anoxygenic Phototrophic Bacterial Community from the Meromictic Lake Trekhtsvetnoe (Kandalaksha Bay,White Sea)

Microbiology - The community of anoxygenic phototrophic bacteria (APB) from the water column of the meromictic Lake Trekhtsvetnoe (Kandalaksha Bay, White Sea, Russia) was studied in March 2012 and...     

Fitness,risk taking,and spatial behavior covary with boldness in experimental vole populations

Individuals of a population may vary along a pace‐of‐life syndrome from highly fecund, short‐lived, bold, dispersive “fast” types at one end of the spectrum to less fecund, long‐lived, shy, plastic “slow” types at the other end. Risk‐taking behavior might mediate the underlying life history trade‐off, but empirical evidence supporting this hypothesis is still ambiguous. Using experimentally created populations of common voles (Microtus arvalis)—a species with distinct seasonal life history trajectories—we aimed to test whether individual differences in boldness behavior covary with risk taking, space use, and fitness. We quantified risk taking, space use (via automated tracking), survival, and reproductive success (via genetic parentage analysis) in 8 to 14 experimental, mixed‐sex populations of 113 common voles of known boldness type in large grassland enclosures over a significant part of their adult life span and two reproductive events. Populations were assorted to contain extreme boldness types (bold or shy) of both sexes. Bolder individuals took more risks than shyer ones, which did not affect survival. Bolder males but not females produced more offspring than shy conspecifics. Daily home range and core area sizes, based on 95% and 50% Kernel density estimates (20 ± 10 per individual, n = 54 individuals), were highly repeatable over time. Individual space use unfolded differently for sex‐boldness type combinations over the course of the experiment. While day ranges decreased for shy females, they increased for bold females and all males. Space use trajectories may, hence, indicate differences in coping styles when confronted with a novel social and physical environment. Thus, interindividual differences in boldness predict risk taking under near‐natural conditions and have consequences for fitness in males, which have a higher reproductive potential than females. Given extreme inter‐ and intra‐annual fluctuations in population density in the study species and its short life span, density‐dependent fluctuating selection operating differently on the sexes might maintain (co)variation in boldness, risk taking, and pace‐of‐life.     

A locus conferring tolerance to Theileria infection in African cattle

East Coast fever, a tick-borne cattle disease caused by the Theileria parva parasite, is among the biggest natural killers of cattle in East Africa, leading to over 1 million deaths annually. Here we report on the genetic analysis of a cohort of Bos indicus (Boran) cattle demonstrating heritable tolerance to infection with T. parva (h² = 0.65, s.e. 0.57). Through a linkage analysis we identify a 6 Mb genomic region on bovine chromosome 15 that is significantly associated with survival outcome following T. parva exposure. Testing this locus in an independent cohort of animals replicates this association with survival following T. parva infection. A stop gained variant in a paralogue of the FAF1 gene in this region was found to be highly associated with survival across both related and unrelated animals, with only one of the 20 homozygote carriers (T/T) of this change succumbing to the disease in contrast to 44 out of 97 animals homozygote for the reference allele (C/C). Consequently, we present a genetic locus linked to tolerance of one of Africa’s most important cattle diseases, raising the promise of marker-assisted selection for cattle that are less susceptible to infection by T. parva.     

ESEEM and Mössbauer studies of the ferriheme model compound bis(3-aminopyrazole)tetraphenylporphyrinatoiron(III) chloride, [TPPFe(NH2PzH)2]Cl

A model heme complex, bis(3-aminopyrazole)tetraphenylporphinatoiron(III) chloride, [TPPFe (NH₂PzH)₂]Cl, for which the EPR g-values lead to a rhombicity V/Δ=1.2 if g _zz is the largest g-value, have been investigated by electron spin echo envelope modulation (ESEEM) and Mössbauer spectroscopies. The ESEEM studies focus on the proton sum frequency peaks at near twice the proton Larmor frequency. Analysis of the distant proton peak (mainly due to the pyrrole-H) at exactly twice the proton Larmor frequency shows conclusively that g _zz is aligned along the normal to the porphyrin plane, and thus the electron configuration is (d _xy )²(d _xz ,d _yz )³, with g _zz >g _yy >g _xx . This system is thus another violation to Taylor's "proper axis system" rule. The near proton (the α-H and N-H of the axial ligands) peaks provide distance information for those protons from the metal. Magnetic Mössbauer studies of the same complex confirm the (d _xy )²(d _xz ,d _yz )³ ground state and indicate that, as is the case for cytochrome P450_cam, A _xx is the largest magnitude A-value, and is negative in sign. Other low-spin iron(III) porphyrinates also have A _xx of negative sign, but usually the magnitude is only about half that of A _zz , which is always positive in sign.     

Microbacterium oxydans, a symbiont of Djungarian hamster, displaying probiotic properties

A resident microorganism (strain Kho-17) was isolated from secretions of the specific glandular structures at the angles of mouth of Djungarian hamster (Phodopus campbelli). According to cultural, morphological, and physiological properties as well as to the phylogenetic analysis basing on the sequences of 16S rRNA gene and analysis of the cell wall the strain was assigned to the species Microbacterium oxydans. The bacterium isolated displayed probiotic properties when administered orally as a suspension of live cells for 20 days to Syrian hamster (Mesocricetus auratus), which manifested themselves in increased body weight and weights of several organs and stimulation of both cell-mediated and humoral immunities.     

UV-B treated algae exhibiting different responses as a food source for Daphnia magna

The response of green algae Scenedesmus quadricauda and Selenastrumcapricornutum to different levels of UV-B radiation was studied.Daphnia magna, the next step in the food web, was fed with UV-Btreated algae. UV-B radiation induced the synthesis of UV absorbingsubstances and photosynthetic pigments, enhanced the level ofrespiratory potential and suppressed growth of the treated algae.Biomass production in S. quadricauda was higher than in S. capricornutum,but the production of photosynthetic pigments and relative amountsof UV absorbing substances as well as respiratory potentialwere more pronounced in S. capricornutum. A short-term feedingexperiment with D. magna showed that in general, females ingestedhigher numbers of cells of algae treated with a high UV-B dose,but the biomass of ingested algae did not differ significantly.The exception was S. capricornutum treated with a high UV-Bdose; a lower biomass was ingested, probably reflecting thesmaller UV-treated cells.     

Probing the role of tryptophans in Aequorea victoria green fluorescent proteins with an expanded genetic code

The expanded genetic code in combination with site-directed mutagenesis was used to probe spectroscopic and structural roles of tryptophan (Trp) residues in Aequorea victoria green fluorescent proteins (avGFPs). Nine different halogen-, chalcogen-, and methyl-containing Trp isosteric analogues and surrogates were incorporated into avGFPs containing indole moieties in, and outside of, the chromophore, by the use of the selective pressure incorporation method. Such isosteric replacements introduced minimal local geometry changes in indole moieties, often to the level of single atomic exchange ('atomic mutation') and do not affect three-dimensional structures of avGFPs but induce changes in spectral properties. Our approach offers a new platform to re-evaluate issues like resonance transfer, mechanisms of chromophore formation and maturation, as well as the importance of local geometry and weak sulphur-aromatic interactions for avGFP spectral properties and structural stability. The library of novel tailor-made avGFP mutants and variants generated in this work has demonstrated not only the potentials of the expanded genetic code to study spectroscopic functions, but also a new approach to generate tailor-made proteins with interesting and useful spectral properties.