Ecological and functional clustering of forestal species in the south western Amazonia.

Agrupamento ecológico e funcional de espécies florestais na Amazônia Sul Ocidental

Heat-induced masculinization in domesticated zebrafish is family-specific and yields a set of different gonadal transcriptomes

Understanding environmental influences on sex ratios is important for the study of the evolution of sex-determining mechanisms and for evaluating the effects of global warming and chemical pollution. Fishes exhibit sexual plasticity, but the underlying mechanisms of environmental effects on their reproduction are unclear even in the well-established teleost research model, the zebrafish. Here we established the conditions to study the effects of elevated temperature on zebrafish sex. We showed that sex ratio response to elevated temperature is family-specific and typically leads to masculinization (female-to-male sex reversal), resulting in neomales. These results uncovered genotype-by-environment interactions that support a polygenic sex determination system in domesticated (laboratory) zebrafish. We found that some heat-treated fish had gene expression profiles similar to untreated controls of the same sex, indicating that they were resistant to thermal effects. Further, most neomales had gonadal transcriptomes similar to that of regular males. Strikingly, we discovered heat-treated females that displayed a normal ovarian phenotype but with a “male-like” gonadal transcriptome. Such major transcriptomic reprogramming with preserved organ structure has never been reported. Juveniles were also found to have a male-like transcriptome shortly after exposure to heat. These findings were validated by analyzing the expression of genes and signaling pathways associated with sex differentiation. Our results revealed a lasting thermal effect on zebrafish gonads, suggesting new avenues for detection of functional consequences of elevated temperature in natural fish populations in a global warming scenario

Identification of transitional disks in Chamaeleon with Herschel

Transitional disks are circumstellar disks with inner holes that in some cases are produced by planets and/or substellar companions in these systems. For this reason, these disks are extremely important for the study of planetary system formation. The Herschel Space Observatory provides an unique opportunity for studying the outer regions of protoplanetary disks. In this work we update previous knowledge on the transitional disks in the Chamaeleon I and II regions with data from the Herschel Gould Belt Survey. We propose a new method for transitional disk classification based on the WISE 12 micron-PACS 70 micron color, together with inspection of the Herschel images. We applied this method to the population of Class II sources in the Chamaeleon region and studied the spectral energy distributions of the transitional disks in the sample. We also built the median spectral energy distribution of Class II objects in these regions for comparison with transitional disks. The proposed method allows a clear separation of the known transitional disks from the Class II sources. We find 6 transitional disks, all previously known, and identify 5 objects previously thought to be transitional as possibly non-transitional. We find higher fluxes at the PACS wavelengths in the sample of transitional disks than those of Class II objects. We show the Herschel 70 micron band to be an efficient tool for transitional disk identification. The sensitivity and spatial resolution of Herschel reveals a significant contamination level among the previously identified transitional disk candidates for the two regions, which calls for a revision of previous samples of transitional disks in other regions. The systematic excess found at the PACS bands could be a result of the mechanism that produces the transitional phase, or an indication of different evolutionary paths for transitional disks and Class II sources.Comment: Accepted for publication in A&A: 11 March 2013 11 pages, 15 figure

Emissão de metano entérico por ovinos alimentados com silagens de sorgo.

A emissão de metano entérico foi avaliada em ovinos recebendo silagens de três híbridos de sorgo (BRS 610, BR 700 e BRS 655) colhidas em três estádios de maturação dos grãos (leitoso, pastoso e farináceo). Os animais receberam a silagem em quantidade suficiente para atender as exigências de consumo de matéria seca para mantença. O delineamento experimental utilizado foi inteiramente casualizado em desenho fatorial 3x3 (híbridos x estádios de maturação) com cinco repetições. A emissão diária de metano entérico não diferiu entre os tratamentos e representou entre 3,87% e 5,54% da energia bruta ingerida (9,74 a 16,03 gramas de metano por dia). Não houve efeito de híbrido sobre a emissão de metano por ovinos. O estádio de maturação do sorgo pode influenciar a emissão de metano entérico por ovinos alimentados com silagem

Far-UV Emissions of the Sun in Time: Probing Solar Magnetic Activity and Effects on Evolution of Paleo-Planetary Atmospheres

We present and analyze FUSE observations of six solar analogs. These are single, main-sequence G0-5 strs selected as proxies for the Sun at several stages of its main-sequence lifetime. The emission features in the FUSE 920-1180 A wavelength range allow for a critical probe of the hot plasma over three decades in temperature. Using the flux ratio CIII 1176/977 as diagnostics, we investigate the dependence of the electron pressure of the transition region as a function of the rotation period, age and magnetic activity. The results from these solar proxies indicate that the electron pressure of the stellar ~10^5-K plasma decreases by a factor of about 70 between the young, fast-rotating magnetically active star and the old, slow-rotating inactive star. Also, the observations indicate that the average surface fluxes of emission features strongly decrease with increasing stellar age and longer rotation period. The emission flux evolution with age or rotation period is well fitted by power laws, which become steeper from cooler chromospheric (10^4 K) to hotter coronal (10^7 K) plasma. The relationship for the integrated (920-1180 A) FUSE flux indicates that the solar far-ultraviolet emissions were about twice the present value 2.5 Gyr ago and about 4 times the present value 3.5 Gyr ago. Note also that the FUSE/FUV flux of the Zero-Age Main Sequence Sun could have been higher by as much as 50 times. Our analysis suggests that the strong FUV emissions of the young Sun may have played a crucial role in the developing planetary system, in particular through the photoionization, photochemical evolution and possible erosion of the planetary atmospheres. (abridged)Comment: 15 pages, 8 figures, accepted for publication in Ap

In vitro multiplication of Swietenia macrophylla King (Meliaceae) from juvenile shoots.

Big-leaf mahogany (Swietenia macrophylla King) is an important species for timber production that is considered the most valuable in the world. For this reason its exploitation is indiscriminate and leads this species to the risk of extinction. Moreover, mahogany is difficult to regenerate naturally and, when used in reforestation programs, plants are severely damaged by the shoot-borer (Hypsipyla grandella Zellar). This work aimed at developing the multiplication stage of micropropagation of Swietenia macrophylla King using juvenile material. After desinfestation, seeds were germinated in MS solid culture medium. Shoot formation from seeds occurred during five months, giving 5.54 nodal segments per seed. These explants were excised, each containing one axillary bud, and transferred on multiplication media. Four experiments with cytokinins were conducted, using media supplemented with 6-benzylaminopurine (BAP) (2.5 to 50.0 ?M), 2- isopentenyladenine (2-iP) (0; 1.1 to 8.8 ?M), combinations of BAP (0; 2.5 to 50.0 ?M) and 2-iP (2.2 ?M). For the first treatments the basal culture medium was MS medium and in the last one MS and QL media were used in separate experiments. When BAP was tested alone, the maximum point of multiplication rate average was obtained on medium containing 23.61 ?M, while 2-iP did not induce bud multiplication. On QL culture medium supplemented with the combinations of BAP (0; 2.5; 5.0; 10.0 e 20.0 ?M ) and 2-iP (2.2 ?M), there was no multiplication. The maximum point of multiplication rate average was 5.7 ?M, obtained when the MS culture medium was supplemented with 18.51 ?M BAP and 2.2 ?M 2-iP

Consumo de energia por ovinos alimentados com silagens de sorgo em diferentes estádios de maturação.

O consumo de energia foi avaliado em ovinos, utilizando-se câmaras respirométricas de fluxo aberto, para as silagens de três híbridos de sorgo (BRS 610, BR 700 e BRS 655) colhidas em três estádios de maturação dos grãos (leitoso, pastoso e farináceo). O delineamento experimental utilizado foi inteiramente casualizado em desenho fatorial 3x3, sendo três híbridos e três estádios de maturação (idades de corte) e cinco repetições (carneiros). A silagem do BRS 610 colhida no estádio pastoso proporcionou maior consumo de energia líquida do que quando colhida no estádio leitoso. Já o BRS 655 apresentou maior consumo de energia líquida quando colhido no estádio pastoso em relação ao estádio farináceo. Para o BR 700 não houve influência da idade de corte sobre esse parâmetro

Desempenho agronômico e produção de matéria seca digestível de híbridos de sorgo com capim sudão, normais e mutantes BMR (portadores de nervura marrom).

O objetivo deste trabalho foi avaliar as características agronômicas e a produção de matéria seca digestível de híbridos de sorgo com capim sudão mutantes BMR (portadores de nervura marrom) em comparação a híbridos normais. Os vinte e cinco híbridos foram avaliados quanto à altura de plantas, número de plantas por hectare, produção de matéria verde por hectare, produção de matéria seca por hectare e produção de matéria seca digestível por hectare. Os valores médios observados foram: 1,42 metros, 187 mil plantaslha, 39,62 tonlha, 3,73 tonlha e 2,65 tonlha, respectivamente para os seguintes parâmetros avaliados: altura de planta, stand de planta, produção de matéria verde, produção de matéria seca e produção de matéria seca digestíveI. De acordo com os resultados apresentados, a mutação com gene BMR expressam de forma desuniforme entre os diferentes cultivares. Em alguns cruzamentos, a inclusão do gene BMR não deprimiu significativamente as características agronômicas avaliadas. A produção de matéria seca digestível não diferiu significativamente entre os materiais avaliados devido à maior digestibilidade da matéria seca observada nos híbridos mutantes BMR

First detection of thermal radio jets in a sample of proto-brown dwarf candidates

We observed with the JVLA at 3.6 and 1.3 cm a sample of 11 proto-brown dwarf candidates in Taurus in a search for thermal radio jets driven by the most embedded brown dwarfs. We detected for the first time four thermal radio jets in proto-brown dwarf candidates. We compiled data from UKIDSS, 2MASS, Spitzer, WISE and Herschel to build the Spectral Energy Distribution (SED) of the objects in our sample, which are similar to typical Class~I SEDs of Young Stellar Objects (YSOs). The four proto-brown dwarf candidates driving thermal radio jets also roughly follow the well-known trend of centimeter luminosity against bolometric luminosity determined for YSOs, assuming they belong to Taurus, although they present some excess of radio emission compared to the known relation for YSOs. Nonetheless, we are able to reproduce the flux densities of the radio jets modeling the centimeter emission of the thermal radio jets using the same type of models applied to YSOs, but with corresponding smaller stellar wind velocities and mass-loss rates, and exploring different possible geometries of the wind or outflow from the star. Moreover, we also find that the modeled mass outflow rates for the bolometric luminosities of our objects agree reasonably well with the trends found between the mass outflow rates and bolometric luminosities of YSOs, which indicates that, despite the "excess" centimeter emission, the intrinsic properties of proto-brown dwarfs are consistent with a continuation of those of very low mass stars to a lower mass range. Overall, our study favors the formation of brown dwarfs as a scaled-down version of low-mass stars.Comment: 18 pages, 8 figures, 14 tables, accepted by the Astrophysical Journa

Proteína bruta e digestibilidade in vitro da matéria seca de híbridos de sorgo com capim sudão, normais e mutantes BMR (portadores de nervura marrom).

O objetivo deste trabalho foi avaliar o valor nutricional de híbridos de sorgo com capim sudão mutantes BMR (portadores de nervura marrom) em comparação a híbridos normais. Os vinte e cinco híbridos foram avaliados quanto ao teor de proteína bruta na matéria seca e a digestibilidade in vitro da matéria seca. O delineamento estatístico utilizado foi o de blocos ao acaso e a comparação das médias pelo teste Scott-Knott com 5% de significância. Os valores de proteína bruta variaram de 9,90 a 14,40% sendo que a média foi de 12,04%. Não foi observado diferença estatística entre os materiais avaliados. Os valores de digestibilidade in vitro da matéria seca variaram de 65,34 a 76,27% sendo que a média foi de 71,56%.. Para este parâmetro foi observado diferença estatística entre os materiais avaliados. A presença do gene BMR foi responsável por melhorar significativamente a digestibilidade in vitro da matéria seca dos híbridos de sorgo com capim Sudão