Emission of volatile halogenated compounds, speciation and localization of bromine and iodine in the brown algal genome model Ectocarpus siliculosus

This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and < 1 order of magnitude for bromine) than e.g. in the kelp Laminaria digitata. Iodide competitively reduces the accumulation of bromide. Both iodide and bromide are accumulated in the cell wall (apoplast) of Ectocarpus, with minor amounts of bromine also detectable in the cytosol. Ectocarpus emits a range of volatile halogenated compounds, the most prominent of which by far is methyl iodide. Interestingly, biosynthesis of this compound cannot be accounted for by vanadium haloperoxidase since the latter have not been found to catalyze direct halogenation of an unactivated methyl group or hydrocarbon so a methyl halide transferase-type production mechanism is proposed

Retinal Specializations In The Eyes Of Deep-Sea Teleosts

Although living beyond the penetration limits of sunlight, many deep-sea teleosts possess large eyes, lenses capable of accommodation, and various adaptations for increasing sensitivity and extending their visual field. However, little is known of the extent of the visual field and whether the spatial resolving power of the eye is constant across the retina. In order to examine whether these fish are specialized for acute vision in particular regions of the visual field, retinal wholemounts were used to examine the regional differences in the density of retinal ganglion cells in 16 species from different depths, habitats and photic zones. It was found that the retinal ganglion cell topography changes markedly across the retina with a density range of 6.3-50.6 x 10/3 cells mm -2 in a pattern unique to each species. A number of mesopelagic species including the lanternfishes, Lampanyctus macdonaldi and Myctophum punctatum possess a concentric increase in cell density towards the retinal margins, putatively enhancing peripheral vision. Three tubular-eyed species including Scopelarchus michaelsarsi possess an area centralis in the centro-lateral region of the main retina supporting the premise that this specialization receives a focused image. Some benthic species such as the smoothhead Rouleina attrita and the searsid Searsia koefoedi also boast a structural specialization or fovea in temporal retina with centro-peripheral cell gradients exceeding 30:1. Benthic species such as the tripodfish Bathypterois dubius possess two regional increases in ganglion cell density or areae centrales, one nasal and the other temporal, thereby increasing spatial resolving power in the caudal and rostral visual fields, respectively. These quantitative analyses suggest that deep-sea fishes, like their shallow-water counterparts, also use a specific region of their visual field for acute vision. This may be an advantage for the detection and localization of bioluminescent light sources

Understanding the potential in vitro modes of action of bis(β‐diketonato) oxovanadium(IV) complexes

To understand the potential in vitro modes of action of bis(β-diketonato) oxovanadium(IV) complexes, nine compounds of varying functionality have been screened using a range of biological techniques. The antiproliferative activity against a range of cancerous and normal cell lines has been determined, and show these complexes are particularly sensitive against the lung carcinoma cell line, A549. Annexin V (apoptosis) and Caspase-3/7 assays were studied to confirm these complexes induce programmed cell death. While gel electrophoresis was used to determine DNA cleavage activity and production of reactive oxygen species (ROS), the Comet assay was used to determine induced genomic DNA damage. Additionally, Förster resonance energy transfer (FRET)-based DNA melting and fluorescent intercalation displacement assays have been used to determine the interaction of the complexes with double strand (DS) DNA and to establish preferential DNA base-pair binding (AT versus GC)

Multiple paternity in a viviparous toad with internal fertilisation

Anurans are renowned for a high diversity of reproductive modes, but less than 1% of species exhibit internal fertilisation followed by viviparity. In the live bearing West African Nimba toad (Nimbaphrynoides occidentalis), females produce yolk-poor eggs and internally nourish their young after fertilisation. Birth of fully developed juveniles takes place after nine months. In the present study, we used genetic markers (eight microsatellite loci) to assign the paternity of litters of 12 females comprising on average 9.7 juveniles. In nine out of twelve families (75%) a single sire was sufficient; in three families (25%) more than one sire was necessary to explain the observed genotypes in each family. These findings are backed up with field observations of male resource defence (underground cavities in which mating takes place) as well as coercive mating attempts, suggesting that the observed moderate level of multiple paternity in a species without distinct sperm storage organs is governed by a balance of female mate choice and male reproductive strategies