Regelmechanismen und Determinanten der Transkription in Polytänchromosomen von Chironomus und Drosophila

Die kumulative Habil.‐Schrift gründet sich auf 6 Originalpublikationen, die beschreiben: [Sass, H. (1982), Cell 28: 269‐278]. RNA polymerase B in polytene chromosomes: Immunofluorescent and autoradiographic analysis during stimulated and repressed RNA synthesis. Elektronenmikroskopie charakterisierte das C. tentans Balbianiring BR2‐Gen von Speicheldrüsenchromosomen als hoch aktives 5‐6 μm langes single‐copy Gen, das 33/μm RNAPolymerasen B (Pol II) transkribieren (Diss., Sass, H., 1978, Univ. Tübingen). Diese Immunfluoreszenzstudie ortet Pol II in allen Interbanden von Region IV‐3B10‐3B5 des nichtinduzierten BR2. Prominente Fluoreszenz im BR2‐Genort 3B9/10 zeigt, das BR2‐Gen ist präaktiv, wie erwartet. 3H‐Autoradiogramme beweisen, in allen fluoreszierenden BR2, BR1, BR3, Puffs, aufgelockerten Banden, Interbanden und Loci ohne Puffing, synthetisiert Pol II RNA. Die genomweite ständige Pol II‐Präsenz zeigt, dass, wie beim nichtinduzierten BR2‐Gen, bereits schon gebundene Pol II wohl auch andere Gene präaktiviert. So erfolgt die Regulation der Transkription mehr über die transkriptionelle Elongation. Auch durch α‐Amanitin, oder Actinomycin D, oder Hitzeschock in vivo kollabierte BR2, BR1, BR3 besitzen Pol II. [Sass, H. (1984), Chromosoma 90: 20‐25]. Gene identification in polytene chromosomes: some Balbiani ring 2 gene sequences are located in an interband‐like region of Chironomus tentans. Immunfluoreszenz und 3H‐Autoradiographie zeigen, dass Injektionen von DRB in Larven die Balbianiringe (BR) sowie andere Puffs und deren Pol II‐Konzentration dramatisch reduzieren. Trotzdem zeigen 3H‐Uridin markierte Speicheldrüsenchromosomen, dass RNA‐Synthese doch in nichtinduzierten BR2, BR1, BR3 erfolgt, aber nur auf reduziertem Level. Das widerspricht der von Egyházi E. (1975, PNAS 73:947‐950) propagierten „Inhibition of Balbiani ring RNA synthesis at the initiation level“ durch DRB. Vielmehr sieht es so aus, DRB wirkt bei der transkriptionellen Elongation inhibierend. Durch in situ‐Hybridisierung von Sequenzen klonierter BR2‐DNA wurde in Speicheldrüsenchromosom IV das BR2‐Gen in Region 3B9/10 direkt identifiziert. [Sass, H. and Pederson, T. (1984), J. Mol. Biol. 180: 911‐926]. Transcription‐dependent localization of U1 and U2 small nuclear ribonucleoproteins at major sites of gene activity in polytene chromosomes. Immunolokalisation von Sm‐, U1‐ und U2snRNP‐spezifischen Antigenen in Speicheldrüsenchromosomen von C. tentans hat zur Entdeckung der beim Spleißen von prä‐mRNA beteiligten U1/U2snRNPs in Balbianiringen BR2, BR1, BR3 sowie anderen Puffs und aufgelockerten Banden geführt. Die überraschenden BR‐Daten zeigen erstmals: (i) Der Spleiß‐Apparat ist in Genloci mit intensiver RNA‐Synthese schon vorhanden. (ii) Immunfluoreszenz reflektiert den Exon‐Intron‐Bau dieser BR‐Gene. (iii) Transkription und spleißosomales Ausschneiden von Introns sind koordiniert. [Sass, H. (1989), Nucleic Acids Research 17: 10508]. Hsp82‐neo transposition vectors to study insertional mutagenesis in Drosophila melanogaster and tissue culture cells; [Sass, H. (1990), Gene 89: 179‐186]. P‐transposable vectors expressing a constitutive and thermoinducible hsp82‐neo fusion gene for Drosophila germline transformation and tissue‐culture transfection. Beschrieben sind Design, Konstruktion und Expression der Genfusion hsp82‐neo als ein in vivo selektierbares Reporter‐/Markergen, die Transposons P{hsp82‐neo/Adh} sowie P{hsp82‐neo} und Transformations‐Vektoren pHS22, pHS24, pHS85, pHS103 und pHS104. Sie stellen das von der Fliege gebildete Enzym bakteriellen Ursprungs, Neomycin‐Phosphotransferase II, für die G418‐Selektion bereit, um die Position, Struktur, Expression und Funktion von Genen mittels hsp82‐neo‐Mutagenese zu erforschen. [Sass, H. and Meselson, M. (1991), Proc. Natl. Acad. Sci. USA 88: 6795‐6799]. Dosage compensation of the Drosophila pseudoobscura Hsp82 gene and the D. melanogaster Adh gene at ectopic sites in D. melanogaster. Quantitative Unterschiede in der Dosiskompensation des X‐chromosomalen hsp82‐Gens von D. pseudoobscura und autosomalen Adh‐Gens von D. melanogaster wurden als Erhöhung der RNAMenge in D. melanogaster gemessen. Beide Transgene sind dosiskompensiert, sprang P{hsp82‐ neo/Adh} in euchromatische Regionen des D. melanogaster X‐Chromosoms. Beide Transgene sind nicht dosiskompensiert, insertierte P{hsp82‐neo/Adh} ins β‐Heterochromatin in Region 20 an der Basis des X. Keine der zehn autosomalen Insertionen ist dosiskompensiert. Die Ergebnisse lassen vermuten, dass X‐chromosomale regulatorische Sequenzen, die für die Verstärkung der Genaktivität um Faktor 2 in Männchen verantwortlich sind, gehäuft im X vorkommen, jedoch im β‐ Heterochromatin und den Autosomen fehlen. Das Kompensationsverhalten der transponierten Gene wird durch das neue chromosomale Milieu des Insertionsortes bestimmt.

Les conflits et les rapports de force dans la langue. Le dominant et le domine dans le domaine scolaire

La standardisation de la langue française a inévitablement eu des conséquences soit dans l’attitude de défense du français, soit dans l’inquiétude de ceux qui parlent une autre langue. Cette étude veut établir une comparaison entre le rapport langue du pouvoir/langues non officielles et le rapport professeur/élève en milieu scolaire. La distinction entre langue officielle et dites « langues minoritaires » sera mis en relation avec la langue des jeunes, qui, à l’école, se confrontent et entrent en collision avec la langue de leur professeur. En effet, les classes hétérogènes et l’influence de la langue maternelle auprès des élèves, fils d’immigrés, exposent les enseignants à toute une série de difficultés liées aux différences culturelles. Les dénonciations et les cas de violence dans les écoles mettront l’accent également sur l’opinion publique et sur le type de mesures mises en relief par les Institutions publiques. L’aire géographique prise en considération inclut Paris et ses environs même si quelques exemples d’enquêtes menées dans d’autres parties de la France et à l’étranger seront cités.

Recruitment dynamics of the grove-dominant tree Microberlinia bisulcata in African rain forest: extending the light response versus adult longevity trade-off concept

In groves of ectomycorrhizal caesalpiniaceous species in the Atlantic coastal forest of Central Africa the dominant tree Microberlinia bisulcata, which is shade-intolerant as a seedling but highly light-responding as a sapling, shows very limited regeneration. M. bisulcata saplings were mapped in an 82.5-ha plot at Korup and found to be located significantly far (>40 m) away from adults, a result confirmed by direct testing in a second 56-ha plot. Sapling growth over 6 years, the distribution of newly emerging seedlings around adults, recruitment of saplings in a large opening and the outward extent of seedlings at the grove edge were also investigated. Two processes appear to have been operating: (1) a very strong and consistent restriction of the very numerous seedlings establishing after masting close to adults, and (2) a strong but highly spatially variable promotion of distant survivors by increased light from the deaths of large trees of species other than M. bisulcata (which itself has very low mortality rate). This leads to an apparent escape-from-adults effect. To maintain saplings in the shade between multiple short periods of release ectomycorrhizal connections to other co-occurring caesalp species may enable a rachet-type mechanism. The recorded sapling dynamics currently contribute an essential part of the long-term cycling of the groves. M. bisulcata is an interesting example of an important group of tropical trees, particularly in Africa, which are both highly light-demanding when young yet capable also of forming very large forest emergents. To more comprehensively explain tropical tree responses, the case is made for adding a new dimension to the trade-off concept of early tree light-response versus adult longevity.

Do fungal pathogens drive density-dependent mortality in established seedlings of two dominant African rain forest trees?

Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipulated the density of recently established seedlings (~5–8 wk old; low vs. high-density) of two dominant species of contrasting recruitment potential, and altered their exposure to pathogens using a broad-spectrum fungicide. Seedling mortality of the abundantly recruiting subcanopy tree Oubanguia alata was strongly density-dependent after 7 mo, yet fungicide-treated seedlings had slightly higher mortality than controls. By contrast, seedling mortality of the poorly recruiting large canopy-emergent tree Microberlinia bisulcata was unaffected by density or fungicide. Ectomycorrhizal colonization of M. bisulcata was not affected by density or fungicide either. For O. alata, adverse effects of fungicide on its vesicular arbuscular mycorrhizas may have offset any possible benefit of pathogen removal. We tentatively conclude that fungal pathogens are not a likely major cause of density dependence in O. alata, or of early post-establishment mortality in M. bisulcata. They do not explain the latter's currently very low recruitment rate at Korup.

Contiguous ∼16 Mb 1p36 deletion: Dominant features of classical distal 1p36 monosomy with haplo-lethality

Monosomy 1p36 results from heterozygous deletions of the terminal short chromosome 1 arm, the most common terminal deletion in humans. The microdeletion is split in two usually non-overlapping and clinically distinct classical distal and proximal 1p36 monosomy syndromes. Using comparative genome hybridization, MLPA and qPCR we identified the largest contiguous ∼16 Mb terminal 1p36 deletion reported to date. It covers both distal and proximal regions, causes a neonatally lethal variant with virtually exclusive features of distal 1p36 monosomy, highlighting the key importance of the gene-rich distal region for the "compound" 1p36 phenotype and a threshold deletion-size effect for haplo-lethality.

Haematological parameters are normal in dominant white Franches-Montagnes horses carrying a KIT mutation

The KIT receptor protein-tyrosine kinase plays an important role during embryonic development. Activation of KIT is crucial for the development of various cell lineages such as melanoblasts, stem cells of the haematopoietic system, spermatogonia and intestinal cells of Cajal. In mice, many mutations in the Kit gene cause pigmentation disorders accompanied by pleiotropic effects on blood cells and male fertility. Previous work has demonstrated that dominant white Franches-Montagnes horses carry one copy of the KIT gene with the p.Y717X mutation. The targeted breeding of white horses would be ethically questionable if white horses were known to suffer from anaemia or leukopenia. The present study demonstrates that no statistically significant differences in peripheral blood parameters are detectable between dominant white and solid-coloured Franches-Montagnes horses. The data indicate that KIT mutations may have different effects in mice, pigs, and horses. The KIT p.Y717X mutation does not have a major negative effect on the haematopoietic system of dominant white horses.

Mitochondrial dysfunction and Purkinje cell loss in autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS)

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a childhood-onset neurological disease resulting from mutations in the SACS gene encoding sacsin, a 4,579-aa protein of unknown function. Originally identified as a founder disease in Québec, ARSACS is now recognized worldwide. Prominent features include pyramidal spasticity and cerebellar ataxia, but the underlying pathology and pathophysiological mechanisms are unknown. We have generated an animal model for ARSACS, sacsin knockout mice, that display age-dependent neurodegeneration of cerebellar Purkinje cells. To explore the pathophysiological basis for this observation, we examined the cell biological properties of sacsin. We show that sacsin localizes to mitochondria in non-neuronal cells and primary neurons and that it interacts with dynamin-related protein 1, which participates in mitochondrial fission. Fibroblasts from ARSACS patients show a hyperfused mitochondrial network, consistent with defects in mitochondrial fission. Sacsin knockdown leads to an overly interconnected and functionally impaired mitochondrial network, and mitochondria accumulate in the soma and proximal dendrites of sacsin knockdown neurons. Disruption of mitochondrial transport into dendrites has been shown to lead to abnormal dendritic morphology, and we observe striking alterations in the organization of dendritic fields in the cerebellum of knockout mice that precedes Purkinje cell death. Our data identifies mitochondrial dysfunction/mislocalization as the likely cellular basis for ARSACS and indicates a role for sacsin in regulation of mitochondrial dynamics.

Passage of Alabama's Hb 56: Fueled By Dominant Anti-Immigration Tropes

Abstract Background. In 2011, Alabama, neither a border state nor hold a significantly large Hispanic population, passed the most restrictive state immigration law, The Beason-Hammon Alabama Taxpayer and Citizen Protection Act, HB 56. This omnibus law was far-reaching in its restrictions, including, but not limited to, identification, public services, employment, housing, and law enforcement. Objectives. This research explores the dominant tropes present in the narrative surrounding the anti-immigration legislative activity in Alabama that created fertile ground for the passage of such a punitive immigration law. Methods. Newspaper articles from 2007 to 2011 in Alabama¿s Birmingham News and Press-Register, the two most circulated newspapers in the state, were attained from NewsLibrary.com, an online database of 5,311 newspapers and other news sources. Results. Seven dominant tropes were identified in the articles that pushed for anti-immigration policies. These tropes claimed (1) the US-Mexico border is not secure, (2) the federal government has failed to enact comprehensive immigration reform, (3) immigrants steal jobs, hurt the economy, and (4) burden public services, (5) immigrants are criminals and terrorists, (6) they refuse to assimilate and learn English, and (7) there has been a dramatic percent change in the Hispanic and illegal populations. These tropes cumulatively worked together to create anti-immigration sentiment that pushed for the passage of HB 56.

Allelic Heterogeneity at the Equine KIT Locus in Dominant White (W) Horses

White coat color has been a highly valued trait in horses for at least 2,000 years. Dominant white (W) is one of several known depigmentation phenotypes in horses. It shows considerable phenotypic variation, ranging from approximately 50% depigmented areas up to a completely white coat. In the horse, the four depigmentation phenotypes roan, sabino, tobiano, and dominant white were independently mapped to a chromosomal region on ECA 3 harboring the KIT gene. KIT plays an important role in melanoblast survival during embryonic development. We determined the sequence and genomic organization of the approximately 82 kb equine KIT gene. A mutation analysis of all 21 KIT exons in white Franches-Montagnes Horses revealed a nonsense mutation in exon 15 (c.2151C>G, p.Y717X). We analyzed the KIT exons in horses characterized as dominant white from other populations and found three additional candidate causative mutations. Three almost completely white Arabians carried a different nonsense mutation in exon 4 (c.706A>T, p.K236X). Six Camarillo White Horses had a missense mutation in exon 12 (c.1805C>T, p.A602V), and five white Thoroughbreds had yet another missense mutation in exon 13 (c.1960G>A, p.G654R). Our results indicate that the dominant white color in Franches-Montagnes Horses is caused by a nonsense mutation in the KIT gene and that multiple independent mutations within this gene appear to be responsible for dominant white in several other modern horse populations.