Plant nuclear gene knockout reveals a role in plastid division for the homolog of the bacterial cell division protein FtsZ, an ancestral tubulin

Little is known about the division of eukaryotic cell organelles and up to now neither in animals nor in plants has a gene product been shown to mediate this process. A cDNA encoding a homolog of the bacterial cell division protein FtsZ, an ancestral tubulin, was isolated from the eukaryote Physcomitrella patens and used to disrupt efficiently the genomic locus in this terrestrial seedless plant. Seven out of 51 transgenics obtained were knockout plants generated by homologous recombination; they were specifically impeded in plastid division with no detectable effect on mitochondrial division or plant morphology. Implications on the theory of endosymbiosis and on the use of reverse genetics in plants are discussed.

Mso1p: A yeast protein that functions in secretion and interacts physically and genetically with Sec1p

The yeast Sec1p protein functions in the docking of secretory transport vesicles to the plasma membrane. We previously have cloned two yeast genes encoding syntaxins, SSO1 and SSO2, as suppressors of the temperature-sensitive sec1–1 mutation. We now describe a third suppressor of sec1–1, which we call MSO1. Unlike SSO1 and SSO2, MSO1 is specific for sec1 and does not suppress mutations in any other SEC genes. MSO1 encodes a small hydrophilic protein that is enriched in a microsomal membrane fraction. Cells that lack MSO1 are viable, but they accumulate secretory vesicles in the bud, indicating that the terminal step in secretion is partially impaired. Moreover, loss of MSO1 shows synthetic lethality with mutations in SEC1, SEC2, and SEC4, and other synthetic phenotypes with mutations in several other late-acting SEC genes. We further found that Mso1p interacts with Sec1p both in vitro and in the two-hybrid system. These findings suggest that Mso1p is a component of the secretory vesicle docking complex whose function is closely associated with that of Sec1p.

A Yeast t-SNARE Involved in Endocytosis

The ORF YOL018c (TLG2) of Saccharomyces cerevisiae encodes a protein that belongs to the syntaxin protein family. The proteins of this family, t-SNAREs, are present on target organelles and are thought to participate in the specific interaction between vesicles and acceptor membranes in intracellular membrane trafficking. TLG2 is not an essential gene, and its deletion does not cause defects in the secretory pathway. However, its deletion in cells lacking the vacuolar ATPase subunit Vma2p leads to loss of viability, suggesting that Tlg2p is involved in endocytosis. In tlg2Δ cells, internalization was normal for two endocytic markers, the pheromone α-factor and the plasma membrane uracil permease. In contrast, degradation of α-factor and uracil permease was delayed in tlg2Δ cells. Internalization of positively charged Nanogold shows that the endocytic pathway is perturbed in the mutant, which accumulates Nanogold in primary endocytic vesicles and shows a greatly reduced complement of early endosomes. These results strongly suggest that Tlg2p is a t-SNARE involved in early endosome biogenesis.

Toward a quantum-mechanical description of metal-assisted phosphoryl transfer in pyrophosphatase

The wealth of kinetic and structural information makes inorganic pyrophosphatases (PPases) a good model system to study the details of enzymatic phosphoryl transfer. The enzyme accelerates metal-complexed phosphoryl transfer 1010-fold: but how? Our structures of the yeast PPase product complex at 1.15 Å and fluoride-inhibited complex at 1.9 Å visualize the active site in three different states: substrate-bound, immediate product bound, and relaxed product bound. These span the steps around chemical catalysis and provide strong evidence that a water molecule (Onu) directly attacks PPi with a pKa vastly lowered by coordination to two metal ions and D117. They also suggest that a low-barrier hydrogen bond (LBHB) forms between D117 and Onu, in part because of steric crowding by W100 and N116. Direct visualization of the double bonds on the phosphates appears possible. The flexible side chains at the top of the active site absorb the motion involved in the reaction, which may help accelerate catalysis. Relaxation of the product allows a new nucleophile to be generated and creates symmetry in the elementary catalytic steps on the enzyme. We are thus moving closer to understanding phosphoryl transfer in PPases at the quantum mechanical level. Ultra-high resolution structures can thus tease out overlapping complexes and so are as relevant to discussion of enzyme mechanism as structures produced by time-resolved crystallography.

Invisible work, unseen hazards: the health of women immigrant household service workers in Spain

BACKGROUND: Household service work has been largely absent from occupational health studies. We examine the occupational hazards and health effects identified by immigrant women household service workers. METHODS: Exploratory, descriptive study of 46 documented and undocumented immigrant women in household services in Spain, using a phenomenological approach. Data were collected between September 2006 and May 2007 through focus groups and semi-structured individual interviews. Data were separated for analysis by documentation status and sorted using a mixed-generation process. In a second phase of analysis, data on psychosocial hazards were organized using the Copenhagen Psychosocial Questionnaire as a guide. RESULTS: Informants reported a number of environmental, ergonomic and psychosocial hazards and corresponding health effects. Psychosocial hazards were especially strongly present in data. Data on reported hazards were similar by documentation status and varied by several emerging categories: whether participants were primarily cleaners or carers and whether they lived in or outside of the homes of their employers. Documentation status was relevant in terms of empowerment and bargaining, but did not appear to influence work tasks or exposure to hazards directly. CONCLUSIONS: Female immigrant household service workers are exposed to a variety of health hazards that could be acted upon by improved legislation, enforcement, and preventive workplace measures, which are discussed.

Automatic Discovery of Word Semantic Relations

In this paper, we propose an unsupervised methodology to automatically discover pairs of semantically related words by highlighting their local environment and evaluating their semantic similarity in local and global semantic spaces. This proposal di®ers from previous research as it tries to take the best of two different methodologies i.e. semantic space models and information extraction models. It can be applied to extract close semantic relations, it limits the search space and it is unsupervised.

Osavaltion on suojeltava kansalaisiaan laittomalta maahanmuutolta — The New York Times ja Kalifornian lakialoite 187 vuonna 1994

Tämän tutkielman aiheena on vuoden 1994 Kalifornian lakialoitteen 187 representaatio The New York Timesissa julkaistuissa teksteissä. Tutkimusmetodina on käytetty diskurssianalyysia. Tutkimus on keskittyy syyskuusta 1994 tammikuuhun 1995 julkaistuihin teksteihin. Tutkimuksessa selvitettiin esitettiinkö lakialoite 187 The New York Timesissa myönteisessä vai kielteisessä valossa, millaisina ilmiöinä siirtolaisuus ja dokumentoimaton maahanmuutto on kuvattu lehdessä sekä miten julkaisussa on uutisoitu lakialoitteen vaikutuksista osa- ja liittovaltiotasolla. The New York Timesin toimittajat sitoivat lakialoitteen 187 käsittelyn osaksi laajempaa poliittista kokonaisuutta, johon kuuluivat samaan aikaan käydyt henkilövaalit. He seurasivat myös lakialoitteen konfliktia liittovaltiotason lainsäädännön kanssa sekä lakialoitteen jäädyttämiseen liittyneitä oikeuskäsittelyitä. Tutkimuksen perusteella The New York Timesin julkaisemien tekstien perusteella Kalifornian lakialoite 187 ei ollut kannatettava hanke. Siirtolaisuus kuvattiin mahdollisena yhteisöllisenä voimavarana ja siirtolaiset potentiaalisina amerikkalaisina. Lain ulkopuolisiin siirtolaisuuden ilmiöihin suhtauduttiin kielteisesti.

Talouskasvun edistäminen köyhyyspolitiikassa

Tutkielman aiheena on köyhyyden vähentäminen talouskasvua edistämällä. Tutkimuskysymys on, miten talouskasvu vaikuttaa köyhyyteen ja kuinka poliittisessa päätöksenteossa voitaisiin huomioida saatuja tutkimustuloksia. Tutkielmassa pyritään tunnistamaan, millaisella politiikalla talouskasvusta saisi köyhiä suosivampaa. Tutkimusmenetelmänä on kirjallisuuskatsaus. Tutkielman johtopäätöksinä todetaan, että talouskasvu keskimäärin hyödyttää köyhiä, mutta valittu empiirinen malli vaikuttaa tuloksiin. Tässä tutkielmassa mukana olleissa empiirisissä malleissa talouskasvu keskimäärin hyödytti köyhiä korkeintaan saman verran kuin muuta väestöä. Tulevaisuudessa köyhyyspolitiikan pitäisi perustua enemmän eriarvoisuuden vähentämiseen kuin talouskasvun edistämiseen. Tällä hetkellä on kuitenkin olemassa alueita, joissa eriarvoisuuden vähentämisellä ei tulla saavuttamaan niin merkittävää köyhyyden vähentymistä kuin talouskasvun avulla on mahdollista. Eriarvoisuus on tekijä, joka vaikuttaa yksilön mahdollisuuksiin ansaita ja kerätä varallisuutta. Lisäksi se on tekijä, joka vaikuttaa siihen, kuinka hyvin valtio onnistuu vähentämään köyhyyttä. Talouskasvun lisäksi valtiossa pitää olla sopivat olosuhteet, jotta köyhyys vähenisi, pelkkä talouskasvu ei ole riittävää. Eriarvoisuuden vähentäminen on keino, jolla talouskasvusta saadaan enemmän irti köyhyyden vähentämiseksi

Caracterización de la función cognitiva de niños con síndrome de down de 5 a 12 años en la ciudad de Bogotá

Los niños que padecen trisomía 21 poseen una serie de características físicas, neurológicas y neuropsicológicas específicas, las cuales han sido investigadas a profundidad en diferentes países, de lo cual se han desarrollado protocolos de evaluación para estos niños acorde a su nacionalidad (García, 2010). A pesar de que Colombia es uno de los países en los cuales el síndrome de Down se presenta con mayor frecuencia, hasta la fecha, no se encuentran estudios que enfaticen en las habilidades neuropsicológicas de esta población específica, por lo cual no se han desarrollado protocolos de evaluación adecuados para los niños con síndrome este síndrome. Esta investigación se llevó acabo con una población de 88 niños a los cuales se les aplicó el inventario de desarrollo BATTELLE, y se identificó que los niños con síndrome Down de 5 a 12 años obtienen un puntaje que se encuentra en 4 desviaciones estándar por debajo de la media típica. Lo anterior demuestra una característica específica de esta población en cuanto a patrones de desarrollo en las cuales, se evidencia dificultad más importante en las área cognición y de la comunicación expresiva. Con respecto a los intervalos de edad se identificó que a lo largo de estos el desempeño en las áreas evaluadas decrece. esto puede estar relacionado con la mayor complejidad de los hitos del desarrollo para una edad esperada. Debido a que los hitos del desarrollo esperados varían a lo largo de los periodos del ciclo vital del ser humano, estos tienden a aumentar su complejidad en etapas del desarrollo más avanzados; como estos niños poseen una serie de dificultades en las funciones ejecutivas y cognición, no lograrán alcanzar dichos hitos del desarrollo.