Diel vertical migration of the prawn larvae of Macrobrachium amazonicum (HELLER, 1862) in a Central Amazonian floodplain lake, Careiro Island, Brazil

Prawn larvae of Macrobrachium amazonicum have been collected during six diel cycles in the epilimnion (surface and 2 m) from three different habitats of the Lago do Rei, Careiro Island. The larval distribution showed a significant increase in density at 22 hours regardless of season or habitat, which suggests a diel vertical migration pattern. The thermal stratification of the lake (mean differential of 0.5 °C between the surface and 2 m and 0.6 °C between 2 m and 4 m) suggests that this phenomena could be only partly related to a metabolic efficiency resulting from prawns residing at cooler depths during the day. In shallow tropical waters, predation by visually dependent planktivores can be a more important factor in the adaptative significance of the diel distribution of the macrozooplankton than a low thermal stratification. The diurnal feeding activity found in the predominant planktivores fish species of the Careiro lake reinforces this hypothesis

Variation in egg size of the fresh-water prawn Macrobrachium amazonicum (Decapoda: Palaemonidae)

Egg size of the fresh-water prawn Macrobrachium amazonicum varied among ecologically isolated or geographically distant populations of the Amazon basin. The mean volume of both recently spawned nonpigmented eggs and older pigmented eyed eggs was smaller in prawns from the Tocantins River (0.14 and 0.20 mm3, respectively) than in those from the middle Amazon (0.17 and 0.25 mm3). The largest eggs (0.19 and 0.27 mm3) were displayed by females from the Iquitos and Guapore Rivers. Since the egg volume was independent of female body size, it was attributed to population specific characteristics. The egg size increased with the distance of the sampling site from the ocean, suggesting a progressive divergence of this species from a typical littoral population to an inland form, in a still active fresh-waterization process similar to the pattern evolved among other species in the genus Macrobrachium

Fishery potential of Macrobrachium amazonicum in Central Amazonia (Careiro Island): abundance and size variation

Abundance and body size variations of the prawn Macrobrachium amazonicum (HELLER, 1862) have been studied in a Central Amazonian floodplain lake, on Careiro Island. The highest number of captures and smallest sizes have been observed beneath floating macrophyte meadows. This suggests that these meadows serve a nursery habitats. The densities registered in the Amazon river were three times lower than in the lake. Maximum densities were recorded during low-water periods, while minimum densities were found during high water periods. These results point to a relationship between current force and catchability. In the floodplain lake, prawn abundance seems to be related to macrophyte expansion during the periods of rising water; the lowest captures were registered at high water, which is probably due to the spatial dispersion as the water volume increases. River prawn populations are characterized by larger sizes than the ones in the lake. They show a well-marked pattern of seasonal variation in size, with larger sizes found during periods of rising water and smaller sizes predominating during high-water periods. On the contrary, lagoonal prawns show maximum sizes during high-water, and smallest sizes during low-water periods. Despite its good fishing potential (up to 200 g/trap), the native prawn is not exploited in the Amazonas, but imported from the State of Pará. Artesanal prawn fishing in floodplain lakes, or extensive culture in ponds for carnivorous fish or human consumption, can be a commercially lucrative activity for sustainable regional economic development

ESTRATÉGIA REPRODUTIVA E ALGUNS ASPECTOS DEMOGRÁFICOS DO CAMARÃO Palaemonetes carteri GORDON, 1935 NA AMAZONIA CENTRAL, RIO NEGRO

A ecologia do camarão Palaemonetes carteri Gordon, 1935 (Decapoda: Palaemonidae) foi estudada através de coletas mensais, realizadas de janeiro 1989 até maio 1990, na região de Manaus. P. carteri vive na liteira submersa dos igarapés de terra firme em áreas baixas inundadas periodicamente pelas enchentes dos rios. A estratégia de reprodução e a dinâmica da razão sexual foram estudados na base dos 4,441 indivíduos coletados. P. carteri mostrou um dimorfismo sexual do comprimento, as fêmeas sendo maiores que os machos. O período de reprodução foi restrito a enchente e a cheia das águas. O número de ovos por fêmea variou entre 5 e 39, sem nenhuma correlação com o tamanho das fêmeas. A razão sexual mostrou uma predominância de fêmeas sem nenhuma variação sazonal significativa

New primary renal diagnosis codes for the ERA-EDTA

The European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) Registry has produced a new set of primary renal diagnosis (PRD) codes that are intended for use by affiliated registries. It is designed specifically for use in renal centres and registries but is aligned with international coding standards supported by the WHO (International Classification of Diseases) and the International Health Terminology Standards Development Organization (SNOMED Clinical Terms). It is available as supplementary material to this paper and free on the internet for non-commercial, clinical, quality improvement and research use, and by agreement with the ERA-EDTA Registry for use by commercial organizations. Conversion between the old and the new PRD codes is possible. The new codes are very flexible and will be actively managed to keep them up-to-date and to ensure that renal medicine can remain at the forefront of the electronic revolution in medicine, epidemiology research and the use of decision support systems to improve the care of patients

Structure of nanoscale mesoporous silica spheres?

Abstract Hexagonal MCM-41 can be transformed into cubic MCM-48 and finally into spherical particles by the addition of alcohol during the synthesis of a mesoporous silica material. X-ray diffraction suggests that the structure of these spherical particles is of the MCM-41 type. Transmission electron microscopy however reveals that the structure of the mesoporous silica spherical particles consists of a core in the form of a truncated octahedron with an MCM-48 cubic structure and radial pores grown on the surfaces of the truncated octahedron. Spherical MCM particles therefore consist of a mixture of cubic and hexagonally arranged pores

The CCR4-NOT Complex Physically and Functionally Interacts with TRAMP and the Nuclear Exosome

BACKGROUND: Ccr4-Not is a highly conserved multi-protein complex consisting in yeast of 9 subunits, including Not5 and the major yeast deadenylase Ccr4. It has been connected functionally in the nucleus to transcription by RNA polymerase II and in the cytoplasm to mRNA degradation. However, there has been no evidence so far that this complex is important for RNA degradation in the nucleus. METHODOLOGY/PRINCIPAL FINDINGS: In this work we point to a new role for the Ccr4-Not complex in nuclear RNA metabolism. We determine the importance of the Ccr4-Not complex for the levels of non-coding nuclear RNAs, such as mis-processed and polyadenylated snoRNAs, whose turnover depends upon the nuclear exosome and TRAMP. Consistently, mutation of both the Ccr4-Not complex and the nuclear exosome results in synthetic slow growth phenotypes. We demonstrate physical interactions between the Ccr4-Not complex and the exosome. First, Not5 co-purifies with the exosome. Second, several exosome subunits co-purify with the Ccr4-Not complex. Third, the Ccr4-Not complex is important for the integrity of large exosome-containing complexes. Finally, we reveal a connection between the Ccr4-Not complex and TRAMP through the association of the Mtr4 helicase with the Ccr4-Not complex and the importance of specific subunits of Ccr4-Not for the association of Mtr4 with the nuclear exosome subunit Rrp6. CONCLUSIONS/SIGNIFICANCE: We propose a model in which the Ccr4-Not complex may provide a platform contributing to dynamic interactions between the nuclear exosome and its co-factor TRAMP. Our findings connect for the first time the different players involved in nuclear and cytoplasmic RNA degradation