Inactivation and self -association of CaM kinase: Effects of ATP, substrate binding domains, and isozymic forms

Calcium/calmodulin-dependent protein kinase II (CaM kinase) is a multifunctional Ser/Thr protein kinase, that is highly enriched in brain and is involved in regulating many aspects of neuronal function. We observed that forebrain CaM kinase from crude homogenates, cytosolic fractions and purified preparations inactivates and translocates into the particulate fraction following autophosphorylation. Using purified forebrain CaM kinase as well as recombinant $\alpha$ isozyme, we determined that the formation of particulate enzyme was due to enzyme self-association. The conditions of autophosphorylation determine whether enzyme self-association and/or inactivation will occur. Self-association of CaM kinase is sensitive to pH, ATP concentration, and enzyme autophosphorylation. This process is prevented by saturating concentrations of ATP. However, in limiting ATP, pH is the dominant factor, and enzyme self-association occurs at pH values $\rm{<}7.0.$ Site-specific mutants were produced by substituting Ala for Thr286, Thr253, or Thr305,306 to determine whether these sites of autophosphorylation affect enzyme inactivation and self-association. The only mutation that influenced these processes was Ala286, which removed the protective effect afforded by autophosphorylation in saturating ATP. Enzyme inactivation occurs in the presence and absence of self-association and appears predominantly sensitive to nucleotide concentration, because saturating concentrations of $\rm Mg\sp{2+}/ADP$ or $\rm Mg\sp{2+}/ATP$ prevent this process. These data implicate the ATP binding pocket in both inactivation and self-association. We also observed that select peptide substrates and peptide inhibitors modeled after the autoregulatory domain of CaM kinase prevented these processes. The $\alpha$ and $\beta$ isozymes of CaM kinase were characterized independently, and were observed to exhibit differences in both enzyme inactivation and self-association. The $\beta$ isozyme was less sensitive to inactivation, and was never observed to self-associate. Biophysical characterization, and transmission electron microscopy coupled with image analysis indicated both isozymes were multimeric, however, the $\alpha$ and $\beta$ isozymes appeared structurally different. We hypothesize that the $\alpha$ subunit of CaM kinase plays both a structural and enzymatic role, and the $\beta$ subunit plays an enzymatic role. The ramifications for the functional differences observed for inactivation and self-association are discussed based on potential structural differences and autoregulation of the $\alpha$ and $\beta$ isozymes in both calcium-induced physiological and pathological processes. ^

Exploring the perception and production of weak and strong forms in English

Como profesoras de Fonética y Fonología Inglesa hemos percibido que nuestros alumnos –hispano-hablantes- enfrentan una serie de dificultades en relación con la percepción y producción de las formas débiles de las palabras estructurales. En consecuencia, evaluamos la percepción y producción de las formas débiles y fuertes en nuestros alumnos, a través de una prueba de escucha y otra de habla, una vez que los estudiantes de primer año de la Facultad de Filosofía, Humanidades y Artes, Universidad Nacional de San Juan (UNSJ), habían finalizado el período de entrenamiento en estas formas. Para la recolección de datos utilizamos dos tipos de tests: uno de percepción y otro de producción. En general, los resultados corroboraron nuestra percepción: los alumnos continuaron teniendo mayor dificultad en la percepción y producción de las formas débiles de las palabras estructurales que en la de las formas fuertes, aún después de haber estado expuestos al entrenamiento explícito.

Planktonic foraminifera of Oligocene sediments from DSDP Hole 77-538A in the Gulf of Mexico

A relatively extended Oligocene pelagic sequence with good to medium recovery, drilled during DSDP Leg 77 in the Gulf of Mexico, yielded rich and well diversified planktonic foraminiferal faunas. Planktonic foraminifera recorded in Hole 538A span the interval from Zone P19 through P22. Evolutionary lineages were observed among the globoquadrinids, the globigerinitids, and the "Globigerina" ciperoensis and Globigerinoides primordius groups. Quantitative analysis of planktonic foraminiferal assemblages shows that faunas fluctuate in abundance and species diversity throughout the sequence. A few of these fluctuations that could be related to selective dissolution are mainly confined to the early-mid Oligocene. A climatic curve was constructed using as warmer indicators, Turborotalia pseudoampliapertura, Globoquadrina tripartita, Dentoglobigerina globularis, Dentoglobigerina baroemoenensis,. "Globigerina" ciperoensis and Globigerinoides groups, and Cassigerinella chipolensis; and as coller indicators, Catapsydrax spp., Globorotaloides spp., Subbotina angiporoides group, Globigerina s. str., and the tenuitellides. Three major intervals are identifiable in the climatic curve: Interval 1 (lower) up to Zone P20 predominantly cooler: Interval 2 (intermediate) up to the upper part of Zone P21a with warm and cool fluctuations: and lnterval 3 (upper), warmer, with a large positive peak, due to abundant "G." angulisuturalis, at the beginning of Zone P21b with recooling midway in Zone P22. In Intervals 1 and 2 planktonic foraminiferal faunas are dominated by temperate forms. Interpretation of planktonic foraminiferal data suggests that cooler water conditions characterize the early-mid Oligocene: during the mid Oligocene (most of Zone P21a) water masses exhibit peculiar characteristics transitional to the warmer waters prevailing during the late Oligocene. Warmer conditions were not definitely settled in Zone P22, however, as indicated by the cooler episode following the warmest peak. These climatic trends are inconsistent with those inferred from oxygen isotopes except at small scale. In fact, oxygen isotope values for Oligocene Atlantic Ocean are too heavy (thus too cool) in comparison with the high abundance and diversity of warm taxa, expecially in Zone P22. When values are lighter (warmer), as in Zone P19 abundance and diversity of warm indices are too low. To explain such a cool isotope values in presence of highly diversified and abundant warm planktonic foraminifera, we suggest (1) that the oxygen isotope ratio used for estimating Oligocene paleotemperatures might be 1? heavier than Eocene values and further increased for the late Oligocene. This hypothesis implies the presence of a relatively extended ice cap in Antarctica in the early and mid Oligocene, and probably an increase in ice volume during the late Oligocenc: (2) heavier isotope values might be related to an increase in salinity, or (3) by a combination of both ice cap and increase in salinity.

Concentrations of labile dissolved forms of Cu, Zn, Pb, and Cu in waters of the Kara Sea and Ob and Yenisey estuaries

Concentrations of labile dissolved forms of Cu, Zn, Pb, and Cu in waters of the Kara Sea and Ob and Yenisey estuaries measured on board during Cruise 49 of R/V Dmitry Mendeleev.

Isotopic composition of various forms of sulfur in barite crusts from the Red Sea rift

Barite crusts were formed by an intermittent hydrothermal vent with output temperature from 85 to 465°C. Principal sources of supply of sulfate sulfur are sea water, evaporites, and tholeiitic basalts of the Red Sea rift. Sulfides and sulfates were formed in conditions of isotope disequilibrium with respect to sulfur because rate of precipitation of sulfur compounds from hydrothermal solution was high compared with rate of isotope exchange.

The Darién Region, Connecting Road of the Americas, among the expressions of hydric wealth, land vocation and the extractive exploration on its violated forms

Colombia has oceanic waters, catchment areas, like lakes, cienagas and swamps, water flows, like rivers, gorges and streams, small rivers and groundwater. The oceanic waters are the Caribbean Sea-1600 km and the Pacific Ocean-1300 km that comprise the north and west continental territory, respectively. Actually the Region of Darién, geographically bounded by the Carribean Sea to the north is becoming to be focused by studies due to use conflicts and disputes about water and a forest reserve on its territories. Considering its location, strategic at northwestern Colombia, frontier region with Central America, several dynamics are imposed. One of them is the implantation of a road system entitled Connecting Road of the Americas. This fact means the construction of an infra-structure that will cross a special zone formed by swamps and jungle known as The Darién Gap. Evidences of such interests are revealed by projects like the constructions of Turbo's Port in the Atlantic Ocean, Department of Antioquia and Tribugá's Port in the Pacific Ocean, Department of Choco, the mountain road and the coastal conection Colombia-Venezuela attending to the main intentions of the central region of the department (Metropolitan Area of Aburrá Valley-AMVA). Human settlements form a productive system, based on small and medium familiar agriculture's production, corresponding to the western portion and piedmont of Abibe's mountain at its antioquian portion, alluvial plan that forms the rivers on this area, the littoral zone that delimits the Carribean Sea, the Darién and Baudó Mountains and the gulf that receives, among other waters, the ones from Atrato and León, as well as the exodus process constitutes a forced exit resulting from actions of several armed groups. It can be identified intense historical, cultural, political and environmental relations, specially the last one associated with strategic ecosystems that are fundamental for the hydric regulation of the region, as well as food safety of the local inhabitants. Results from two researches (UPB, 2007 y 2010) reveals this quick transformation in the spatial re-configuration, demographical and economical indicators and the exacerbated fight for resources, damaging the extractive vocation in the Region. Path to commerce of illegalities (drugs, guns) and to implementation of the agroindustrial project for biofuel production, cooperation program that involves Venezuela, Brazil and Colombia. Appropriation modes allow the existence of strategies since global interests revealing a development logic that privileges the conception of an artificialized nature. Since the smallest portion of rural areas, specific modes of resources exploration are linked to imposed interests of transnational corporations. Disparate consequences are going deeper evidenced by social, technical and nature transformations, envisioning risks for the habitability's condition