Sequence-Based Mapping and Genome Editing Reveal Mutations in Stickleback Hps5 Cause Oculocutaneous Albinism and the casper Phenotype.

Here, we present and characterize the spontaneous X-linked recessive mutation casper, which causes oculocutaneous albinism in threespine sticklebacks (Gasterosteus aculeatus). In humans, Hermansky-Pudlak syndrome results in pigmentation defects due to disrupted formation of the melanin-containing lysosomal-related organelle (LRO), the melanosome. casper mutants display not only reduced pigmentation of melanosomes in melanophores, but also reductions in the iridescent silver color from iridophores, while the yellow pigmentation from xanthophores appears unaffected. We mapped casper using high-throughput sequencing of genomic DNA from bulked casper mutants to a region of the stickleback X chromosome (chromosome 19) near the stickleback ortholog of Hermansky-Pudlak syndrome 5 (Hps5). casper mutants have an insertion of a single nucleotide in the sixth exon of Hps5, predicted to generate an early frameshift. Genome editing using CRISPR/Cas9 induced lesions in Hps5 and phenocopied the casper mutation. Injecting single or paired Hps5 guide RNAs revealed higher incidences of genomic deletions from paired guide RNAs compared to single gRNAs. Stickleback Hps5 provides a genetic system where a hemizygous locus in XY males and a diploid locus in XX females can be used to generate an easily scored visible phenotype, facilitating quantitative studies of different genome editing approaches. Lastly, we show the ability to better visualize patterns of fluorescent transgenic reporters in Hps5 mutant fish. Thus, Hps5 mutations present an opportunity to study pigmented LROs in the emerging stickleback model system, as well as a tool to aid in assaying genome editing and visualizing enhancer activity in transgenic fish

Do the BEAF insulator proteins regulate genes involved in cell polarity and neoplastic growth?

AbstractIt was reported that a chromosome with the BEAFNP6377 (NP6377) allele leads to a loss of cell polarity and neoplastic growth in Drosophila melanogaster when homozygous (Gurudatta et al., 2012). We had previously generated the BEAFAB-KO (AB-KO) allele by homologous recombination and did not note these phenotypes (Roy et al., 2007). Both alleles are null mutations. It was unclear why two null alleles of the same gene would give different phenotypes. To resolve this, we performed genetic tests to explore the possibility that the chromosome with the NP6377 allele contained other, second site mutations that might account for the different phenotypes. We found that the chromosome with NP6377 has at least two additional mutations. At least one of these, possibly in combination with the NP6377 allele, is presumably responsible for the reported effects on gene expression, cell polarity and neoplastic growth

Book Reviews

Book Review 1Book Title: Social Behaviour in AnimalsBook Author: N. TinbergenChapman & Hall, London, 1988.Book Review 2Book Title: Plankton Ecology. Succession in plankton communitiesBook Author: Edited by U. SommerSpringer-Verlag, New York, 1989. x + 369 pages.Book Review 3Book Title: Intrazooplankton PredationBook Authors: Edited by H.J. Dumont, J.G. Tundisi & K. RocheKluwer Academic Publishers, Dordrecht, 1990. 242 pages

Targeted gene replacement by homologous recombination in Drosophila stimulates production of second-site mutations

Gene replacement by homologous recombination is a powerful technique for generating mutations in Drosophila. While using this technique for the BEAF gene, we encountered non-targeted lethal mutations on the target chromosome that complicated the analysis of the BEAF mutations until they were discovered and removed by meiotic recombination. Subsequent experiments indicated that the gene-targeting method leads to a modest but significant three-fold increase in the rate of production of non-targeted lethal mutations. It is important to be aware of this phenomenon when using this method. © 2010 Landes Bioscience

Creating Informal Play Opportunities: Are Parents\u27 and Preschoolers\u27 Initiations Related to Children\u27s Competence With Peers?

Preschoolers\u27 social competence may depend on the frequency with which informal play activities are initiated by parents\u27, children, and playmates. In this study, measures of children\u27s peer relations in informal and school contexts and the frequency of parents\u27, children\u27s, and peers\u27 play initiations were obtained with 83 preschool children and their families on 2 occasions. Frequent parent initiations were associated with higher levels of prosocial behavior, lower levels of nonsocial behavior and, among boys, greater peer acceptance in preschools. Children who were more initiating of informal peer contacts displayed less anxious behavior in school and were better liked by their classmates. Finally, the degree to which parents involved children in the process of arranging informal play activities was positively related to the frequency with which children initiated their own peer contacts

On the application of loss functions for determining hazardous concentrations

The Hazardous Concentration to x% of an assemblage (HCx) of biological species is the environmental concentration which for a randomly selected species from the assemblage yields an x% probability of violating the species’ toxicological endpoint. Probabilistic methods for estimating the HCx appeal to the probabilistic concept of Species Sensitivity Distributions (SSDs) – a statistical proxy description of interspecies variation within the assemblage. A commonly used estimator class, derived by Aldenberg and Jaworska (2000; Ecotoxicol Environ Saf 46: 1-18), appealed to classical sampling theory, but also coincided with a Bayesian estimator. Two popular estimators from the class are the 50% and 95% (one-sided) underestimate of the HCx. However, whilst choice of x can have ecological significance, choice of confidence remains arbitrary. We reduce the problem to a Bayesian decision theoretic one; and show that their estimator class is equivalent to Bayes Rules under a class of (a-) symmetric linear loss functions, parameterised by the relative cost of over-estimation to under-estimation. A loss function in this sense measures the ‘cost’, which needn’t be monetary, of over- and under-estimation of the HCx estimator. Bayes rules are estimators which minimise expected loss with respect to the posterior SSD – updated with respect to the toxicity data. This potentially opens the way for high-stakes realism to be incorporated into risk assessments. We propose an alternative loss function known as Scaled LINear Exponential (LINEX) which is non-linearly asymmetric in a precautionary way, such that overestimation and underestimation are punished at an exponential and linear rate respectively. We use this loss function to derive an alternative class of HCx estimators