Integrated top-down and bottom-up proteomics mass spectrometry for the characterization of endogenous ribosomal protein heterogeneity / 药物分析学报

Ribosomes are abundant,large RNA-protein complexes that are the sites of all protein synthesis in cells.Defects in ribosomal proteins(RPs),including proteoforms arising from genetic variations,alternative splicing of RNA transcripts,post-translational modifications and alterations of protein expression level,have been linked to a diverse range of diseases,including cancer and aging.Comprehensive character-ization of ribosomal proteoforms is challenging but important for the discovery of potential disease biomarkers or protein targets.In the present work,using E.coli 70S RPs as an example,we first developed a top-down proteomics approach on a Waters Synapt G2 Si mass spectrometry(MS)system,and then applied it to the HeLa 80S ribosome.The results were complemented by a bottom-up approach.In total,50 out of 55 RPs were identified using the top-down approach.Among these,more than 30 RPs were found to have their N-terminal methionine removed.Additional modifications such as methylation,acetylation,and hydroxylation were also observed,and the modification sites were identified by bottom-up MS.In a HeLa 80S ribosomal sample,we identified 98 ribosomal proteoforms,among which multiple truncated 80S ribosomal proteoforms were observed,the type of information which is often overlooked by bottom-up experiments.Although their relevance to diseases is not yet known,the integration of top-down and bottom-up proteomics approaches paves the way for the discovery of proteoform-specific disease biomarkers or targets.

Functional discovery and production technology for natural bioactive peptides / 生物工程学报

Bioactive peptides play important roles in promoting human health, such as lowering blood pressure, blood sugar and blood lipid, anti-obesity, and anti-cancer. Thus, exploring functional bioactive peptides and developing efficient production technologies are of crucial importance. Herein, we review the development of function discovery and production technology for natural bioactive peptides. Presently, the top-down and bottom-up approaches are mainly used for the function discovery and production of natural active peptides. The top-down approach includes the direct extraction and identification for functional discovery, and the direct extraction, enzymatic hydrolysis and microbial fermentation for production. The bottom-up approach includes the polypeptide modification and database mining for functional discovery, and the chemical synthesis, enzyme synthesis, recombinant expression and cell-free synthesis for production. The top-down approach is usually associated with complicated process, lower efficiency, higher cost, harder quality control, and uncertain functionality, while the bottom-up approach is more suitable for the development of peptide drugs but difficult to be used for functional foods. With the technology development of sequencing and mass spectrometry, it is easier to obtain the proteomic information of various organisms at the molecular level. Based on the proteomic information, the top-down and bottom-up approaches can be combined to overcome the disadvantages of using these two approaches alone, thus providing a new strategy for the rapid development and production of natural active peptides.

Characteristics of visual conduction under Top-down perceptual processing / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To study the visual efficiency and characteristics of Top-down perceptual pathway in children.<p>METHODS: Totally 26 children volunteers in the outpatient department from January to June 2020 were selected. We adopted the photos of children's self-face as the Top-down perceptive fixation point pictures. The N75 time, P100 peak time, P100 amplitude and P100 repolarization time were recorded by graphic visual evoked potential(PVEP)examination.<p>RESULTS: Different visual perception pathway had no significant effect on the latency of N75, while different spatial frequencies have a significant effect on the N75 time. The latency of N75 was prolonged under high frequency spatial stimulation. The interaction between visual perceptual processing path and spatial frequency has a significant effect on the peak time of P100.Under Top-down condition, the peak time of P100 was significantly shortened under high-frequency spatial stimulus. Different visual perception paths and spatial frequencies had significant effects on P100 amplitude, and Top-down perceptual processing and spatial frequencies had significant effects on the time of P100 wave repolarization, while the interaction between processing paths and spatial frequencies had no significant effects.<p>CONCLUSION:Under Top-down visual perceptual, the visual conduction velocity and visual condition efficiency are improved in children's visual process.

Estimativa das emissões veiculares na região metropolitana de Fortaleza, CE, ano-base 2010 / Vehicular emissions estimate in the Fortaleza, Ceará, Brazil, metropolitan region in 2010

RESUMO No Brasil e no mundo, o setor dos transportes de passageiros e cargas tem contribuído decisivamente para o aumento das emissões de poluentes atmosféricos, com os consequentes problemas para o meio ambiente e para a saúde humana. Assim, muitos estudos têm recorrido a metodologias e/ou ferramentas específicas para modelar e simular poluentes atmosféricos. A frota de veículos no Ceará teve um crescimento de 169% nos últimos 10 anos, mas ainda se desconhece o volume de poluentes emitidos pela frota circulante da Região Metropolitana de Fortaleza (RMF). Nesse contexto, foram estimadas as emissões veiculares de escapamento para a RMF no ano de 2010. A quantificação das emissões de monóxido de carbono (CO), hidrocarbonetos não metano (NMHC), óxidos de nitrogênio (NOx), material particulado (MP) e aldeídos (RCHO) foi realizada através da metodologia bottom-up. De modo geral, as motocicletas apresentaram emissões significativas de poluentes, sobretudo de CO, NOx e MP, devido à grande quantidade de veículos na região. Os veículos ciclo Otto representam mais de 90% das emissões totais de CO, NMHC e RCHO, enquanto os veículos ciclo Diesel emitem mais de 85% das emissões totais de NOx e MP.

ABSTRACT In Brazil and worldwide, the passenger and cargo transportation sectors have decisively been responsible for the increased emissions of air pollutants, which cause serious damages for the environment and human health, as well. Thus, many studies have been carried out to model and simulate pollutant emissions through methodologies and/or specific tools. The vehicle fleet in the state of Ceará has increased by 169% over the last 10 years and, until now, the amount of pollutants released from circulating fleet of the Fortaleza Metropolitan Region (FMR) is unknown. In this context, vehicular exhaust emissions for the FMR were estimated for the year 2010. Emission estimates of carbon monoxide (CO), non-methane hydrocarbons (NMHC), nitrogen oxides (NOx), particulate matter (PM), and aldehydes (RCHO) were performed through the bottom-up methodology. In general, it was observed that motorcycles emitted high amounts of pollutants, mainly CO, NOx and MP, due to the large number of vehicles in the region. Otto cycle vehicles accounted for more than 90% of CO, NMHC and RCHO total emissions, while Diesel cycle vehicles emitted more than 85% of NOx and PM total emissions.

La gobernabilidad migratoria en Sudamérica: la difusión de abajo hacia arriba (ascendente) del Acuerdo de Residencia del Mercosur / Migration governance in south america: the bottom-up diffusion of the residence agreement of mercosur / A governança migratória na américa do sul: a difusão de baixo para cima (bottom-up) do acordo de residência do mercosul

Abstract This article offers a complementary explanation to the diffusion theory that focuses on the process of governance emergence from a top-down perspective. This complementary explanation analyzes the bottom-up processes of diffusion and tested them by studying the policy formulation process in the Mercosur Residence Agreement (RA) signed in 2002. Based on interviews with key actors, documents, and academic literature, this article concludes that the RA was mainly the result of Brazilian and Argentinian negotiations. Brazil needed to boost regional cooperation after the Mercosur crisis, and considered that a joint migration amnesty could have a positive impact on the trading bloc's image. However, the Argentinian experience in migration issues allowed for a more coherent policy on the matter. Therefore, I maintain that the mode of interaction in the Residence Agreement negotiations was a bottom up diffusion process that allowed the regionalization of domestic policies.

Resumen Este artículo ofrece una explicación complementaria a la teoría de la difusión que se centra en el proceso de emergencia de la gobernanza desde una perspectiva de arriba hacia abajo (top-down). Esta explicación complementaria analiza los procesos de abajo hacia arriba (bottom-up) de difusión y los prueba mediante el estudio de la formulación de políticas en el Acuerdo de Residencia del Mercosur, firmado en el 2002. En base a entrevistas con actores clave, documentos y literatura académica, este artículo concluye que el Acuerdo fue principalmente el resultado de las negociaciones brasileñas y argentinas. Brasil necesitaba impulsar la cooperación regional después de la crisis del Mercosur y consideró que una amnistía migratoria conjunta podría tener un impacto positivo en la imagen del bloque. Sin embargo, la experiencia argentina en temas de migración permitió una política más coherente en la materia. Por lo tanto, se sostiene que el modo de interacción en las negociaciones del Acuerdo fue un proceso de difusión de abajo hacia arriba (bottom-up) que posibilitó la regionalización de las políticas domésticas.

Resumo Este artigo oferece uma explicação complementar à teoria da difusão que explica o processo de surgimento da governança regional a partir de uma perspectiva de cima para baixo (top-down). Essa explicação complementar analisa os processos de difusão de baixo para cima (bottom-up), e os testa por meio do estudo da formulação de políticas no Acordo de Residência do Mercosul, assinado em 2002. Tomando em consideração entrevistas com atores destacados, documentos e literatura acadêmica, este artigo conclui que o Acordo foi principalmente o resultado das negociações brasileiras e argentinas. O Brasil em um primeiro momento considerou uma anistia migratória regional para melhorar a imagem do Mercosul. No entanto, a experiência argentina em questões de migração permitiu uma política mais coerente na matéria. Portanto, este trabalho conclui que o modo de interação na negociação do Acordo foi um processo de difusão de baixo para cima (bottom-up) que produziu a regionalização de políticas domésticas.

Top-down vs. Bottom-up: alterações no processamento de informações durante a indução de fadiga mental / Top-down vs. bottom-up: alterations in information processing during mental fatigue induction

A Fadiga Mental (FM) ocorre durante ou após um período prolongado de demanda cognitiva repetitiva somado a recompensas insatisfatórias. Este estudo pretende investigar alterações no processamento de informações top-down e bottom-up nocontrole inibitório durante a indução de FM através do protocolo de tarefa cognitiva por tempo prolongado. Participaram do experimento 19 sujeitos (9 homens) com idades entre 18 e 24 anos (M=21,21 DP=1,77), submetidos ao paradigma Go/NoGo contendo cinco blocos de 250 tentativas com intervalos de 30 segundos entre blocos, totalizando 50 minutos de atividade. A ANOVA para medidas repetidas sugere efeito significativo do tempo de realização da tarefa no aumento no tempo de reação do processamento top-down, F4,15 = 3,66, p<0,05, no número de erros por omissão, F4,15 = 4,75, p<0,05, e uma redução no tempo de resposta do processamento bottom-up, F4,15 = 5,39, p<0,05. Estes achados sugerem que a realização de uma tarefa cognitiva durante um período prolongado provoca prejuízo significativo no desempenho cognitivo, com ênfase no processamento de informações top-down, não impedindo a realização de um comportamento, mas prejudicando sua qualidade de execução.

Mental Fatigue (FM) occurs during or after a prolonged period of repetitivecognitive demand coupled with unsatisfactory rewards. This study intends toinvestigate changes in the processing of top-down and bottom-up information oninhibitory control during FM induction through the cognitive task protocol for aprolonged time. A total of 19 subjects (9 males) aged 18 to 24 years (M = 21.21 SD= 1.77) were submitted to the Go / NoGo paradigm containing five blocks of 250trials with 30-second intervals between blocks, totalizing 50 minutes of activity.The ANOVA for repeated measures suggests a significant effect of the time ofaccomplishment of the task in the increase in the time of reaction of the top-downprocessing, F4,15 = 3.66, p <0.05, in the number of errors by default, F4,15 = 4.75, p<0.05, and a reduction in response time of bottom-up processing, F4.15 = 5.39, p<0.05. These findings suggest that performing a cognitive task over a prolongedperiod causes significant impairment in cognitive performance, with an emphasison top-down information processing, not hindering the performance of a behaviorbut impairing its quality of execution.

Review and prospect on preparation technology of drug nanocrystals in the past thirty years / 药学学报

Nanocrystals is a hot topic of poorly soluble drug delivery system under development. Nanocrystals is different from the nanoparticles for drug unloading in polymer materials, and nanocrystals is different from solid dispersion system, in which the drug maintains crystals state. Nanocrystals has a simple preparation process, represents an effective technology in the improvement of solubility and bioavailability of poorly soluble drugs, and has a very promising industrialization application and development potential. In this paper, we retrospect the development history of drug nanocrystals technology, review development of the preparation methods of nanocrystals, and analyze the existing problems to provide a reference to the development of drug nanocrystals preparation.

Neural Signature for Auditory Hallucinations in Schizophrenia: A High-Resolution Positron Emission Tomography Study with Fludeoxyglucose (¹⁸F)

OBJECTIVE: Auditory hallucinations (AHs) are a core symptom of schizophrenia. We investigated the neural signature of AHs by comparing hallucinating patients with schizophrenia with non-hallucinating patients with schizophrenia. METHODS: We recruited hallucinating patients with schizophrenia meeting the criteria for persistent, prominent, and predominant AHs (n=10) and non-hallucinating patients with schizophrenia (n=12). Various clinical assessments were performed incluing Psychotic Symptom Rating Scale for Auditory Hallucinations. Using fludeoxyglucose (¹⁸F) positron emission tomography, regional differences in neural activity between the groups were analyzed. RESULTS: The regions of interest analysis showed significantly lower standardized uptake value ratio (SUVR) in the superior, middle, and inferior frontal gyri, and higher SUVR in the putamen in patients with AHs versus patients without AHs. These findings were confirmed in the voxel-wise analysis. CONCLUSION: Our findings indicate that hypoactivity in the frontal and cingulate gyri, coupled with hyperactivity in the temporal gyrus and putamen, may contribute to the pathophysiology of AHs.

The effects of endogenous and exogenus orienting of attention on source memory / Efectos de la orientación de la atención endógena y exógena en la memoria de contexto

Abstract The aim of this study was to determine the effects of endogenous and exogenous orienting of attention on episodic memory. Thirty healthy participants performed a cueing attention paradigm during encoding, in which images of common objects were presented either to the left or to the right of the center of the screen. Before the presentation of each image, three types of symbolic cues were displayed to indicate the location in which the stimuli would appear: valid cues to elicit endogenous orientation, invalid cues to prompt exogenous orientation and neutral or uncued trials. The participants' task was to discriminate whether the images were symmetrical or not while fixating on the center of the screen to assure the manifestation of only covert attention mechanisms. Covert attention refers to the ability to orient attention by means of central control mechanisms alone, without head and eye movements. Trials with eye movements were excluded after inspection of eye-tracker recordings that were conducted throughout the task. During retrieval, participants conducted a source memory task in which they indicated the location where the images were presented during encoding. Memory for spatial context was superior during endogenous orientation than during exogenous orientation, whereas exogenous orientation was associated with a greater number of missed responses compared to the neutral trials. The formation of episodic memory representations with contextual details benefits from endogenous attention.

Resumen El objetivo del estudio fue determinar los efectos de la orientación de la atención endógena y exógena en la memoria episódica. Treinta participantes sanos realizaron el paradigma de atención con claves durante la codificación, en el que se presentaron imágenes a la izquierda o derecha del centro de la pantalla. Antes de cada imagen se proyectaron tres tipos de claves que indicaban el lugar en el que se presentaría la imagen: claves válidas (orientación endógena), claves inválidas (orientación exógena) y claves neutras. Los participantes tenían que discriminar si las imágenes eran simétricas o no mientras fijaban su mirada al centro de la pantalla para asegurar solo la manifestación de mecanismos de atención encubierta. La atención encubierta se refiere a la habilidad para orientar la atención sólo por medio de mecanismos de control central sin movimientos de los ojos o la cabeza. Los ensayos con movimientos oculares fueron excluidos después de inspeccionar los registros de movimientos oculares. En la recuperación, los participantes realizaron una tarea de memoria de contexto en la que indicaron la posición en la que se había presentado cada imagen durante la codificación. La recuperación del contexto espacial fue superior en los ensayos de orientación endógena que en los ensayos de orientación exógena. La formación de representaciones de la memoria episódica con detalles contextuales se beneficia de los mecanismos de atención endógena.

Estimated evolution of total pollutant gas emissions associated with vehicle activity in the Metropolitan Region of Porto Alegre until 2030

ABSTRACT In recent years, the majority of economic sectors in Brazil have gone through processes of development and transformation. These processes have led to increases in environmental pollution of all kinds; air pollution being one of the most adverse. The Brazilian transportation sector, which heavily affects the air quality, experienced a significant increase in its vehicle fleet thus provoking larger emissions of pollutant gases, mainly in regions with high population density such as the Metropolitan Region of Porto Alegre (MRPA). Within this research, considering mainly the ozone precursor species and Carbon Monoxide and using the year 2001 as a base year, scenarios are obtained for vehicular emissions of pollutant gases in the MRPA until the year 2030. In addition, scenarios related to the evolution of the study region's vehicle fleet were estimated. The statistical tool LEAP (Long Range Energy Alternatives Planning System) was used. The scenario analysis shows that the vehicle fleet will grow exponentially until 2030, considering that the Light Flex vehicles category will mainly contribute to this increase. It is also noted that vehicle emissions of CO, NOx, and THC decrease in the region. The decrease is caused mainly by the renewal of technology in new vehicles and the implementation of emission control programs created by the government.

Revisiting happiness: Frequency versus intensity / Redefiniendo la felicidad: frecuencia versus intensidad

Abstract Mexico is consistently portrayed as a happy country. Research endeavors, both national and international, show that Mexico's levels of happiness are favorable, although little has been done regarding specific measurement underpinnings. There is a constant debate on whether happiness should be measured in terms of frequency or intensity of positive affect over negative affect (Diener, Sandvik, & Pavot, 2009), although some consensus points toward frequency's superiority over intensity of emotions. Some authors insist that frequency can me more easily and accurately measured than intensity, allowing for cross-person metric comparisons. This research put to test the frequency-intensity debate by providing several conceptual frameworsk that accentuated one over the other, allowing people to decide how they defined their own happiness. Two independent samples (n 1 = 158, n 2 = 583) of Mexican men and women provided insights on whether happiness in Mexico is defined in terms of frequency or intensity. Once it was defined, happiness levels were compared between two groups showing that those who define happiness as "frequency" present higher levels of joy. This research supports the premise that happiness could be defined as the sum of frequent events, congruent with bottom-up approaches to happiness and wellbeing.

Resumen México es consistentemente definido como un país feliz. Algunas investigaciones, tanto nacionales como internacionales, muestran que los niveles de felicidad de México son favorables, aunque poco se ha hecho respecto a algunos aspectos clave sobre la medición de la felicidad. Existe un constante debate sobre si la felicidad debe ser medida en términos de intensidad o de frecuencia de afecto positivo sobre afecto negativo (Diener, Sandvik y Pavot, 2009), aunque existe cierto acuerdo en torno a la superioridad de la frecuencia sobre la intensidad. Algunos insisten en que la frecuencia puede ser medida de manera fácil y precisa, permitiendo una métrica comparable entre individuos. Esta investigación tuvo como propósito poner a prueba el debate de frecuencia-intensidad al proveer diferentes esquemas en torno a la felicidad, permitiendo que la gente eligiera cómo se define esta. Dos muestras independientes (n1 = 158, n2 = 583) de hombres y mujeres mexicanos proveen información útil sobre cómo se define en México la felicidad. Una vez definida, se compararon los niveles de felicidad de 2 grupos, obteniendo resultados que apuntan a mayores niveles de felicidad en aquellos que la definen en términos de «frecuencia¼. Estos hallazgos apoyan la premisa de que la felicidad puede ser entendida como la suma de componentes básicos que ocurren con relativa frecuencia, congruente con las posturas teóricas de «abajo-arriba¼ (sumativas) en torno al estudio del bienestar y la felicidad.

International experience on the division and cooperation among medical institutions and its implications for China:An analysis of the UK, Germany, Singapore and the US / 中国卫生政策研究

Through defining the connotation of division and cooperation among medical institutions, this paper introduces the current status for division and cooperation among medical institutions of Britain, Germany, Singapore and USA. The advantages include excellent general practices, optimal health resource allocation, effective first treat-ment in community health facilities, and effective two-way referral. We analyzed the influence of some new policies on the division and cooperation among medical institutions such as medical association, managed care and the General Practices’ service contract. This provided a lot of experience and revelations, including the dynamics to promote the division and cooperation, the separation of outpatient services and inpatient services, privatization of primary medical institutions, division and cooperation between medical institutions and nursing, rehabilitation institutions, distinguis-hing the division and cooperation from hospitals alliance, and division and cooperation among medical institutions can not resolve the all issues in the medical care supply system.

Obstacles and strategies on bottom-up cascading healthcare practice in China / 中国卫生政策研究

In this paper, we describe mismatch, chaos, and disorder behavior during healthcare seeking. Such structural imbalances, scarcity and surplus make healthcare services less efficient. We give reasons for such phenomena in terms of long-term effects of health resource allocation policy-making and implementation, inherent de-fects within healthcare insurance, incomplete market development, and cultural issues. We then propose four policy strategies, including rational price mechanism, strict referral healthcare system, confidence in basic healthcare facili-ties, and proper healthcare cultures. These will restore orderly healthcare behavior and help realize expectations for the current healthcare reform in China.

Dental implant bottom-up cost analysis / 대한치과보철학회지

PURPOSE: The purpose of this study was to estimate the cost of dental implant using the bottom-up approach with the current data from dental clinics. MATERIALS AND METHODS: In this study, direct and indirect costs required for each treatment were calculated using the bottom-up approach. In the bottom-up costing, the average monthly total cost of dental clinic includes labor and material costs, administrative expenses, medical malpractice costs, and opportunity costs of invested capital. For the dental implant cost components, those include direct costs (labor costs, laboratory costs, material costs, depreciation or other operating costs), indirect costs (administrative costs), and the opportunity costs of investment for dental clinic. RESULTS: Dental implant costs of metal crown, porcelain crown and over-denture were 1,449,000 won, 1,583,000 won, and 2,471,000 won respectively. The proportion of cost components was as follows. The labor cost were 50%, and material, administrative and other cost were 33%, 15% and 2%, respectively. For direct, indirect and investment cost, the ratio were 83%, 15% and 2%, respectively. CONCLUSION: The labor costs were evaluated to comprise largest proportion (about 50%, 730,000 won). Dental implant cost using Bottom-up costing was 1,450,000 won for metal crown and 1,580,000 won for porcelain crown.

Effects of short-term sediment nutrient enrichment and grazer (Neritina reclivata) removal on sediment microalgae in a shallow eutrophic estuary (Alabama, USA)

The olive snail (Neritina reclivata) is ubiquitous in tropical and sub-tropical systems of the Gulf of Mexico, however its impacts on sediment microalgae have been little studied. Many coastal systems around the world are being eutrophied due to human activities, and seemingly they will continue to be eutrophied to a further extent in the future. Exploring the single and combined impacts of further nutrient enrichment and grazing by the olive snail on sediment microalgae in such eutrophic systems is an important question for our understanding and management of these systems. Here we examine the effects of short-term nutrient enrichment and grazing by the olive snail N. reclivata on sediment microalgal biomass and composition in a shallow eutrophic estuary (Weeks Bay, Alabama, USA) of the Northern Gulf of Mexico. For this, we performed a series of factorial experiments adding or not nutrients and removing or not the snail, for a total of four treatments in each experiment: ambient grazing, ambient nutrients; ambient grazing, increased nutrients; no grazing, ambient nutrients; and no grazing, increased nutrients. We did not find any significant impact of nutrient addition in any of the eight short-term (i.e. four days) experiments carried out. Impacts by the snail were minor; we only found a decrease in biomass due to snail grazing in one of the eight experiments, and no impacts on microalgal (i.e. diatom) composition. High ambient nutrient concentrations in the sediment porewater and low snail abundances on the sediment could explain these findings. Our results suggest that ephemeral, short-term nutrient pulses into eutrophic coastal systems of the Northern Gulf of Mexico, such as Weeks Bay (Alabama, USA), should not greatly affect the abundance of sediment microalgae, even though those pulses occur in well-lit areas. The results further suggest the snail N. reclivata is not a major control of sediment microalgal populations in the subtidal sedimentary areas studied. Our findings contrast with the results of past work in sediments with well-lit and nutrient poor conditions, or sediments with high densities of other snail grazers. In conjunction this and other investigations indicate that the response of sediment microalgae to nutrient enrichment and modified grazer abundance depends to a large extent on the initial levels of nutrient availability and grazing before the system is altered.

El caracol Neritina reclivata está presente en los sistemas tropicales y subtropicales del Golfo de México, sin embargo, su impacto en los sedimentos de microalgas ha sido poco estudiado. Muchos de los sistemas costeros de todo el mundo están siendo eutrofizados debido a actividades humanas, y al parecer van a seguir siendo eutrofizados en mayor grado en el futuro. La exploración de los efectos individuales y combinados de un mayor enriquecimiento de nutrientes y la herviboría por este caracol en microalgas de sedimentos en estos sistemas eutróficos es una cuestión importante para la comprensión y el manejo de estos sistemas. Aquí se examinan los efectos a corto plazo del enriquecimiento de nutrientes y herviboría del caracol de olivo sobre la biomasa y composición de microalgas de sedimentos en un estuario eutrófico superficial (Weeks Bay. Alabama, USA) del norte del Golfo de México. Para esto se llevaron a cabo una serie de experimentos factoriales añadiendo o no nutrientes y removiendo o no el caracol, para un total de cuatro tratamientos en cada experimento: ambiente con herviboría sin nutrimentos añadidos, ambiente con herviboría y nutrimentos añadidos, ambiente sin herviboría sin nutrimentos añadidos, y ambiente sin herviboría con nutrimentos añadidos. No se encontró ningún impacto significativo por la adición de nutrimentos en ninguno de los ocho experimentos a corto plazo (i.e. cuatro días). Los impactos debidos al caracol fueron menores, sólo se encontró un decrecimiento en la biomasa por herviboría del caracol en uno de los ocho experimentos, y no hubo impacto en la composición de microalgas (i.e. diatomeas). Ambientes con alta concentración de nutrimentos del sedimento y baja abundancia del caracol sobre el sedimento pueden explicar estos resultados. Los resultados obtenidos sugieren que pulsos efímeros y de corto plazo en sistemas costeros eutrofizados del Norte del Golfo de México tal como Weeks Bay (Alabama, USA), no deberían afectar de gran manera la abundancia de microalgas sobre el sedimento, a pesar de que los pulsos ocurran en áreas bien iluminadas. Además los resultados sugieren que el caracol N. reclivata no ejerce mayor control sobre las poblaciones de microalgas en las áreas submareales y sedimentarias estudiadas. Nuestros hallazgos contrastan con resultados de trabajos anteriores en sedimentos con buena iluminación y pobres condiciones nutritivas, o sedimentos con altas densidades de otros caracoles herbívoros. En conjunto, esta y otras investigaciones indican que la respuesta de microalgas en sedimentos al enriquecimiento de nutrientes y abundancia modificada de herbívoros depende en gran medida de los niveles iniciales de disponibilidad de nutrientes y herviboría antes de que el sistema se vea alterado.

Principles of nanoscience: An overview.

The scientific basis of nanotechnology as envisaged from the first principles is compared to bulk behavior. Development of nanoparticles having controllable physical and electronic properties has opened up possibility of designing artificial solids. Top down and bottom up approaches are emphasized. The role of nanoparticle (quantum dots) application in nanophotonics (photovoltaic cell), and drug delivery vehicle is discussed. Fundamentals of DNA structure as the prime site in bionanotechnological manipulations is also discussed. A summary of presently available devices and applications are presented.

Comparative growth of the intertidal barnacle Tetraclita stalactifera (Thoracica: Tetraclitidae) in sites influenced by upwelling and tropical conditions at the Cabo Frio region, Brazil

El crecimiento del cirripedio intermareal Tetraclita stalactifera fue comparado en dos sitios influenciados por condiciones de resurgencia y tropicales en la región del Cabo Frio, Brasil. La hipótesis fue que el crecimiento es más grande en el sitio con más elevada producción. En esta región, cinco cuadrantes de 10 x 10 cm fueron raspados en el intermareal de las costas rocosas, en cada una de estas localidades, para estudiar el crecimiento de T. stalactifera desde el reclutamiento hasta finalizar el experimento o la muerte del individuo. El diámetro de la base de T. stalactifera fue medido para 18 individuos en el sitio tropical (Ponta da Fortaleza) y 22 en el sitio de resurgencia (Ponta da Cabeza) por medio de fotografías digitalizadas y el software ImageTool. Los resultados observados mostraron una mayor tasa de crecimiento en el área bajo la influencia tropical (0.07 mm/día) que en el área bajo influencia de resurgencia (0.06 mm/día). La localización del sitio, periodo de resurgencia o periodo del asentamiento no afectaron las tasas de crecimiento. Otros efectos o interacciones sinérgicas como la temperatura y la disponibilidad de alimento pueden afectar el crecimiento de esta especie en la región.

Growth of the intertidal barnacle Tetraclita stalactifera was compared in two sites under upwelling and tropical influence at Cabo Frio region, Brazil. The hypothesis was that growth is higher at sites with an enhanced productivity. Five quadrates of 10 x 10 cm were cleared in an intertidal zone of each site to follow growth from recruitment and onwards. Base diameters were measured for 18 individuals at the tropical site (Ponta da Fortaleza) and 22 at the upwelling site (Ponta da Cabeça) using digitalized photos and ImageTool software. Mean growth rates were 0.07 mm/day at the tropical site and 0.06 mm/day at the site under upwelling influence. No effect of location, upwelling season or settlement time was found on barnacle growth rates. Other factors or synergic interactions such as temperature and food availability could influence T. stalactifera growth.