Germ cell development in the Honeybee (Apis mellifera); Vasa and Nanos expression

BACKGROUND: Studies of specification of germ-cells in insect embryos has indicated that in many taxa the germ cells form early in development, and their formation is associated with pole plasm, germ plasm or an organelle called the oosome. None of these morphological features associated with germ cell formation have been identified in the Honeybee Apis mellifera. In this study I report the cloning and expression analysis of Honeybee homologues of vasa and nanos, germ cell markers in insects and other animals. RESULTS: Apis vasa and nanos RNAs are present in early honeybee embryos, but the RNAs clear rapidly, without any cells expressing these germ cell markers past stage 2. These genes are then only expressed in a line of cells in the abdomen from stage 9 onwards. These cells are the developing germ cells that are moved dorsally by dorsal closure and are placed in the genital ridge. CONCLUSION: This study of the expression of germ cell markers in the honeybee implies that in this species either germ cells are formed by an inductive event, late in embryogenesis, or they are formed early in development in the absence of vasa and nanos expression. This contrasts with germ cell development in other members of the Hymenoptera, Diptera and Lepidoptera

Tailless patterning functions are conserved in the honeybee even in the absence of Torso signaling

AbstractIn Drosophila, the maternal Torso terminal signaling pathway activates expression of the gene tailless (tll), which is required for the patterning of anterior and posterior termini. We cloned the honeybee orthologue of tll (Am-tll) and found that embryonic expression of Am-tll resembles that of Drosophila, with expression in triangular anterior dorsal–lateral domains and a posterior cap. Functional studies revealed that Am-tll has an essential role in patterning the posterior terminal segments and the brain, similar to the activity of tll in other insects. As the honeybee genome lacks many of the components of the Torso pathway required for terminal patterning, we investigated the regulation of honeybee tailless (Am-tll). Am-tll is expressed maternally and, in the honeybee ovary, Am-tll mRNA becomes localized to the dorsal side of the oocyte, a process requiring the actin cytoskeleton. This RNA becomes redistributed in early embryos to a posterior domain. We also show that the activation of the anterior domain of Am-tll is dependent on honeybee orthodenticle-1. Together these findings indicate major differences in post-transcriptional regulation of tailless in the honeybee compared to other insects but that this regulation leads to a conserved expression pattern. These results provide an example of an early event in development evolving and yet still producing a conserved output for the rest of development to build upon

Evolution of the insect Sox genes

<p>Abstract</p> <p>Background</p> <p>The <it>Sox </it>gene family of transcriptional regulators have essential roles during development and have been extensively studied in vertebrates. The mouse, human and <it>fugu </it>genomes contain at least 20 <it>Sox </it>genes, which are subdivided into groups based on sequence similarity of the highly conserved HMG domain. In the well-studied insect <it>Drosophila melanogaster</it>, eight <it>Sox </it>genes have been identified and are involved in processes such as neurogenesis, dorsal-ventral patterning and segmentation.</p> <p>Results</p> <p>We examined the available genome sequences of <it>Apis mellifera, Nasonia vitripennis, Tribolium castaneum</it>, <it>Anopheles gambiae </it>and identified <it>Sox </it>family members which were classified by phylogenetics using the HMG domains. Using <it>in situ </it>hybridisation we determined the expression patterns of eight honeybee <it>Sox </it>genes in honeybee embryo, adult brain and queen ovary. <it>AmSoxB </it>group genes were expressed in the nervous system, brain and Malphigian tubules. The restricted localization of <it>AmSox21b </it>and <it>AmSoxB1 </it>mRNAs within the oocyte, suggested a role in, or that they are regulated by, dorsal-ventral patterning. <it>AmSoxC, D </it>and <it>F </it>were expressed ubiquitously in late embryos and in the follicle cells of the queen ovary. Expression of <it>AmSoxF </it>and two <it>AmSoxE </it>genes was detected in the drone testis.</p> <p>Conclusion</p> <p>Insect genomes contain between eight and nine <it>Sox </it>genes, with at least four members belonging to <it>Sox </it>group B and other <it>Sox </it>subgroups each being represented by a single <it>Sox </it>gene. Hymenopteran insects have an additional <it>SoxE </it>gene, which may have arisen by gene duplication. Expression analyses of honeybee <it>SoxB </it>genes implies that this group of genes may be able to rapidly evolve new functions and expression domains, while the combined expression pattern of all the <it>SoxB </it>genes is maintained.</p

The evaluation of Education Maintenance Allowance Pilots: three years' evidence: a quantitative evaluation

This is the third report of the longitudinal quantitative evaluation of Education Maintenance Allowance (EMA) pilots and the first since the government announced that EMA is to be rolled out nationally from 2004. The evaluation was commissioned in 1999, by the Department for Education and Skills (DfES) from a consortium of research organisations, led by the Centre for Research in Social Policy (CRSP) and including the National Centre for Social Research, the Institute for Fiscal Studies (IFS) and the National Institute for Careers Education and Counselling (NICEC). The statistical evaluation design is a longitudinal cohort study involving large random sample surveys of young people (and their parents) in 10 EMA pilot areas and eleven control areas. Two cohorts of young people were selected from Child Benefit records. The first cohort of young people left compulsory schooling in the summer of 1999 and they, and their parents, were interviewed between October 1999 and April 2000 (Year 12 interview). A second interview was carried out with these young people between October 2000 and April 2001 (Year 13 interview). The second cohort left compulsory education the following summer of 2000 and young people, and their parents, were first interviewed between October 2000 and April 2001. The report uses both propensity score matching (PSM) and descriptive techniques, each of which brings their own particular strengths to the analysis

National evaluation of the neighbourhood nurseries: integrated report

Report description: The NNI was launched in 2001 to provide high quality childcare in the most disadvantaged neighbourhoods of England, to help parents into employment, reduce child poverty and boost children’s development. By 2005 45,000 new childcare places had been created in approximately 1,400 neighbourhood nurseries. This report brings together the findings of the four individual strands of the National Evaluation of Neighbourhood Nurseries Initiative as shown above and makes a number of recommendations. The report shows the rationale for the government’s strategy in targeting disadvantaged neighbourhoods and in focusing on high quality childcare to provide the link between raising parental employment and income and improving children’s life chances

Germ cell specification and ovary structure in the rotifer Brachionus plicatilis

<p>Abstract</p> <p>Background</p> <p>The segregation of the germline from somatic tissues is an essential process in the development of all animals. Specification of the primordial germ cells (PGCs) takes place via different strategies across animal phyla; either specified early in embryogenesis by the inheritance of maternal determinants in the cytoplasm of the oocyte ('preformation') or selected later in embryonic development from undifferentiated precursors by a localized inductive signal ('epigenesis'). Here we investigate the specification and development of the germ cells in the rotifer <it>Brachionus plicatilis</it>, a member of the poorly-characterized superphyla Lophotrochozoa, by isolating the <it>Brachionus </it>homologues of the conserved germ cell markers <it>vasa </it>and <it>nanos</it>, and examining their expression using <it>in situ </it>hybridization.</p> <p>Results</p> <p><it>Bpvasa </it>and <it>Bpnos </it>RNA expression have very similar distributions in the <it>Brachionus </it>ovary, showing ubiquitous expression in the vitellarium, with higher levels in the putative germ cell cluster. <it>Bpvas </it>RNA expression is present in freshly laid eggs, remaining ubiquitous in embryos until at least the 96 cell stage after which expression narrows to a small cluster of cells at the putative posterior of the embryo, consistent with the developing ovary. <it>Bpnos </it>RNA expression is also present in just-laid eggs but expression is much reduced by the four-cell stage and absent by the 16-cell stage. Shortly before hatching of the juvenile rotifer from the egg, <it>Bpnos </it>RNA expression is re-activated, located in a subset of posterior cells similar to those expressing <it>Bpvas </it>at the same stage.</p> <p>Conclusions</p> <p>The observed expression of <it>vasa </it>and <it>nanos </it>in the developing <it>B. plicatilis </it>embryo implies an epigenetic origin of primordial germ cells in Rotifer.</p

The democratic origins of the term "group analysis": Karl Mannheim's "third way" for psychoanalysis and social science.

It is well known that Foulkes acknowledged Karl Mannheim as the first to use the term ‘group analysis’. However, Mannheim’s work is otherwise not well known. This article examines the foundations of Mannheim’s sociological interest in groups using the Frankfurt School (1929–1933) as a start point through to the brief correspondence of 1945 between Mannheim and Foulkes (previously unpublished). It is argued that there is close conjunction between Mannheim’s and Foulkes’s revision of clinical psychoanalysis along sociological lines. Current renderings of the Frankfurt School tradition pay almost exclusive attention to the American connection (Herbert Marcuse, Eric Fromm, Theodor Adorno and Max Horkheimer) overlooking the contribution of the English connection through the work of Mannheim and Foulkes

Pattern languages in HCI: A critical review

This article presents a critical review of patterns and pattern languages in human-computer interaction (HCI). In recent years, patterns and pattern languages have received considerable attention in HCI for their potential as a means for developing and communicating information and knowledge to support good design. This review examines the background to patterns and pattern languages in HCI, and seeks to locate pattern languages in relation to other approaches to interaction design. The review explores four key issues: What is a pattern? What is a pattern language? How are patterns and pattern languages used? and How are values reflected in the pattern-based approach to design? Following on from the review, a future research agenda is proposed for patterns and pattern languages in HCI

Evolutionary origin and genomic organisation of runt-domain containing genes in arthropods

<p>Abstract</p> <p>Background</p> <p>Gene clusters, such as the <it>Hox </it>gene cluster, are known to have critical roles in development. In eukaryotes gene clusters arise primarily by tandem gene duplication and divergence. Genes within a cluster are often co-regulated, providing selective pressure to maintain the genome organisation, and this co-regulation can result in temporal or spatial co-linearity of gene expression. It has been previously noted that in <it>Drosophila melanogaster</it>, three of the four runt-domain (RD) containing genes are found in a relatively tight cluster on chromosome 1, raising the possibility of a putative functional RD gene cluster in <it>D. melanogaster</it>.</p> <p>Results</p> <p>To investigate the possibility of such a gene cluster, orthologues of the <it>Drosophila melanogaste</it>r RD genes were identified in several endopterygotan insects, two exopterygotan insects and two non-insect arthropods. In all insect species four RD genes were identified and orthology was assigned to the <it>Drosophila </it>sequences by phylogenetic analyses. Although four RD genes were found in the crustacean <it>D. pulex</it>, orthology could not be assigned to the insect sequences, indicating independent gene duplications from a single ancestor following the split of the hexapod lineage from the crustacean lineage.</p> <p>In insects, two chromosomal arrangements of these genes was observed; the first a semi-dispersed cluster, such as in <it>Drosophila</it>, where <it>lozenge </it>is separated from the core cluster of three RD genes often by megabases of DNA. The second arrangement was a tight cluster of the four RD genes, such as in <it>Apis mellifera</it>.</p> <p>This genomic organisation, particularly of the three core RD genes, raises the possibility of shared regulatory elements. <it>In situ </it>hybridisation of embryonic expression of the four RD genes in <it>Drosophila melanogaster </it>and the honeybee <it>A. mellifera </it>shows no evidence for either spatial or temporal co-linearity of expression during embryogenesis.</p> <p>Conclusion</p> <p>All fully sequenced insect genomes contain four RD genes and orthology can be assigned to these genes based on similarity to the <it>D. melanogaster </it>protein sequences. Examination of the genomic organisation of these genes provides evidence for a functional RD gene cluster. RD genes from non-insect arthropods are also clustered, however the lack of orthology between these and insect RD genes suggests this cluster is likely to have resulted from a duplication event independent from that which created the insect RD gene cluster. Analysis of embryonic RD gene expression in two endopterygotan insects, <it>A. mellifera </it>and <it>D. melanogaster</it>, did not show evidence for coordinated gene expression, therefore while the functional significance of this gene cluster remains unknown its maintenance during insect evolution implies some functional significance to the cluster.</p