RESUMO

One of the well-documented effects of regional warming in Antarctica is the impact on flora. Warmer conditions modify several leaf anatomical traits of Antarctic vascular plants, increasing photosynthesis and growth. Given that CO2 and water vapor partially share their diffusion pathways through the leaf, changes in leaf anatomy could also affect the hydraulic traits of Antarctic plants. We evaluated the effects of growth temperature on several anatomical and hydraulic parameters of Antarctic plants and assessed the trait co-variation between these parameters and photosynthetic performance. Warmer conditions promoted an increase in leaf and whole plant hydraulic conductivity, correlating with adjustments in carbon assimilation. These adjustments were consistent with changes in leaf vasculature, where Antarctic species displayed different strategies. At higher temperature, Colobanthus quitensis decreased the number of leaf xylem vessels, but increased their diameter. In contrast, in Deschampsia antarctica the diameter did not change, but the number of vessels increased. Despite this contrasting behavior, some traits such as a small leaf diameter of vessels and a high cell wall rigidity were maintained in both species, suggesting a water-conservation response associated with the ability of Antarctic plants to cope with harsh environments.

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The standard genetic code determines that in most species, including viruses, there are 20 amino acids that are coded by 61 codons, while the other three codons are stop triplets. Considering the whole proteome each species features its own amino acid frequencies, given the slow rate of change, closely related species display similar GC content and amino acids usage. In contrast, distantly related species display different amino acid frequencies. Furthermore, within certain multicellular species, as mammals, intragenomic differences in the usage of amino acids are evident. In this communication, we shall summarize some of the most prominent and well-established factors that determine the differences found in the amino acid usage, both across evolution and intragenomically.

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RESUMO

EPS-producing LAB are widely used in the dairy industry since these polymers improve the viscosity and texture of the products. Besides, EPS might be responsible for several health benefits attributed to probiotic strains. However, growth conditions (culture media, temperature, pH) could modify EPS production affecting both technological and probiotic properties. In this work, the influence of growth temperature on EPS production was evaluated, as well as the consequences of these changes in the probiotic properties of the strains. All Lactobacillus paracasei strains used in the study showed changes in EPS production caused by growth temperature, evidenced by the appearance of a high molecular weight fraction and an increment in the total amount of produced EPS at lower temperature. Nevertheless, these changes do not affect the probiotic properties of the strains; L. paracasei strains grown at 20 °C, 30 °C and 37 °C were able to survive in simulated gastrointestinal conditions, to adhere to Caco-2 cells after that treatment and to modulate the epithelial innate immune response. The results suggest that selected L. paracasei strains are new probiotic candidates that can be used in a wide range of functional foods in which temperature could be used as a tool to improve the technological properties of the product.

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Several authors have called attention to the evolutionary importance of phenotypic plasticity and niche construction, because such phenomena require a new status and a new perspective. Drosophila species are traditionally used as models in investigations of phenotypic plasticity, although the majority of such research has been conducted with species of the subgenus Sophophora, primarily Drosophila melanogaster. In this study, we investigated the phenotypic plasticity of Drosophila cardini, a Neotropical species of the subgenus Drosophila, and focused on the wing size, wing shape, thorax length and wing: thorax ratio of lines that were collected in the Brazilian savanna and exposed to different temperatures during growth. All of the analyzed traits presented plasticity to temperature, and the reaction norms were similar to those previously found in other drosophilid species; in addition, the maximum values were consistent with the temperature variations at the collection sites. The specimens that emerged at low temperatures were larger and had more rounded wings compared with those that emerged at high temperatures, which were smaller and had narrower wings. We hypothesized that the differences observed in the shape of the wings might be associated with flight performance. Nevertheless, further investigation of the relationships among wing shape, wing loading and flight performance is required. Investigations on phenotypic plasticity using species with diverse ecologies should help us to better understand how this phenomenon operates in nature, and studies of this type must be encouraged.

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Para sobreviverem na temperatura corpórea de seu hospedeiro, os fungos patogênicos têm desenvolvido mecanismos moleculares importantes, como a expressão de proteínas relacionadas ao crescimento em altas temperaturas. Assim, o objetivo deste trabalho foi analisar o crescimento in vitro de Conidiobolus lamprauges em diferentes temperaturas e comparar o perfil de proteínas expressas através de eletroforese bidimensional (2D), em duas temperaturas distintas, sendo uma considerada baixa (28°C) e alta (37°C). Para análise do crescimento em diferentes temperaturas, cinco isolados de C. lamprauges, oriundos de ovinos doentes, foram incubados a 20, 25, 30, 35 e 40°C e o crescimento radial foi medido a cada 24 horas. Para análise da expressão diferencial, realizou-se a extração de proteínas do fungo cultivado a 28°C e a 37°C por 48 horas. A média de crescimento radial dos isolados foi diferente nas temperaturas analisadas, sendo 35°C a melhor temperatura para crescimento em todas as amostras. A temperatura ótima ajustada variou entre 33,3°C a 34,8°C. Os limites inferior e superior de inibição de crescimento foram 18°C e 42°C, respectivamente. Na análise da expressão diferencial, foram encontrados 16 spots diferencialmente expressos, sete (7/16) estavam com expressão diminuída e nove (9/16) com expressão aumentada a 37°C, quando comparado a 28°C. Além disso, oito spots estavam presentes apenas a 28°C e seis a 37°C. Sugere-se que C. lamprauges produza um perfil de proteínas relacionadas à termorregulação desencadeado pela alta temperatura do hospedeiro.(AU)

To survive at the body temperature of their hosts, pathogenic fungi have developed important molecular mechanisms, such as protein expression associated with growth at high temperatures. Thus, the aim of this study was to analyze the in vitro growth of Conidiobolus lamprauges at different temperatures and compare proteins expressed by two-dimensional electrophoresis (2D), for the pathogen cultivated at low (28°C) and high (37°C) temperatures. For the analysis of growth temperatures, five isolates of C. lamprauges from sick sheep were incubated at 20, 25, 30, 35 and 40°C and radial growth was measured every 24 hours. For the analysis of differential expression, protein extraction and two-dimensional polyacrylamide gel electrophoresis were performed with C. lamprauges cultivated at 28°C and 37°C for 48 hours. The average radial growth was different at the temperatures tested, and 35°C was found to be the best growth temperature for all isolates. The optimum adjusted temperature ranged between 33.3°C and 34.8°C. The upper and lower limits of growth inhibition were 18°C and 42°C, respectively. Upon expression analysis, a total of 16 spots were differentially expressed, seven (7/16) proteins were downregulated and nine (9/16) were over-expressed at 37ºC compared to 28°C. In addition, eight spots were present only at 28ºC and six were present only at 37ºC. It is suggested that C. lamprauges produces a profile of proteins that is related to thermoregulation triggered by the high temperature of the host.(AU)

Assuntos

RESUMO

Para sobreviverem na temperatura corpórea de seu hospedeiro, os fungos patogênicos têm desenvolvido mecanismos moleculares importantes, como a expressão de proteínas relacionadas ao crescimento em altas temperaturas. Assim, o objetivo deste trabalho foi analisar o crescimento in vitro de Conidiobolus lamprauges em diferentes temperaturas e comparar o perfil de proteínas expressas através de eletroforese bidimensional (2D), em duas temperaturas distintas, sendo uma considerada baixa (28°C) e alta (37°C). Para análise do crescimento em diferentes temperaturas, cinco isolados de C. lamprauges, oriundos de ovinos doentes, foram incubados a 20, 25, 30, 35 e 40°C e o crescimento radial foi medido a cada 24 horas. Para análise da expressão diferencial, realizou-se a extração de proteínas do fungo cultivado a 28°C e a 37°C por 48 horas. A média de crescimento radial dos isolados foi diferente nas temperaturas analisadas, sendo 35°C a melhor temperatura para crescimento em todas as amostras. A temperatura ótima ajustada variou entre 33,3°C a 34,8°C. Os limites inferior e superior de inibição de crescimento foram 18°C e 42°C, respectivamente. Na análise da expressão diferencial, foram encontrados 16 spots diferencialmente expressos, sete (7/16) estavam com expressão diminuída e nove (9/16) com expressão aumentada a 37°C, quando comparado a 28°C. Além disso, oito spots estavam presentes apenas a 28°C e seis a 37°C. Sugere-se que C. lamprauges produza um perfil de proteínas relacionadas à termorregulação desencadeado pela alta temperatura do hospedeiro.

To survive at the body temperature of their hosts, pathogenic fungi have developed important molecular mechanisms, such as protein expression associated with growth at high temperatures. Thus, the aim of this study was to analyze the in vitro growth of Conidiobolus lamprauges at different temperatures and compare proteins expressed by two-dimensional electrophoresis (2D), for the pathogen cultivated at low (28°C) and high (37°C) temperatures. For the analysis of growth temperatures, five isolates of C. lamprauges from sick sheep were incubated at 20, 25, 30, 35 and 40°C and radial growth was measured every 24 hours. For the analysis of differential expression, protein extraction and two-dimensional polyacrylamide gel electrophoresis were performed with C. lamprauges cultivated at 28°C and 37°C for 48 hours. The average radial growth was different at the temperatures tested, and 35°C was found to be the best growth temperature for all isolates. The optimum adjusted temperature ranged between 33.3°C and 34.8°C. The upper and lower limits of growth inhibition were 18°C and 42°C, respectively. Upon expression analysis, a total of 16 spots were differentially expressed, seven (7/16) proteins were downregulated and nine (9/16) were over-expressed at 37ºC compared to 28°C. In addition, eight spots were present only at 28ºC and six were present only at 37ºC. It is suggested that C. lamprauges produces a profile of proteins that is related to thermoregulation triggered by the high temperature of the host.

RESUMO

All organisms that have been studied until now have been found to have differential distribution of simple sequence repeats (SSRs), with more SSRs in intergenic than in coding sequences. SSR distribution was investigated in Archaea genomes where complete chromosome sequences of 19 Archaea were analyzed with the program SPUTNIK to find di- to penta-nucleotide repeats. The number of repeats was determined for the complete chromosome sequences and for the coding and non-coding sequences. Different from what has been found for other groups of organisms, there is an abundance of SSRs in coding regions of the genome of some Archaea. Dinucleotide repeats were rare and CG repeats were found in only two Archaea. In general, trinucleotide repeats are the most abundant SSR motifs; however, pentanucleotide repeats are abundant in some Archaea. Some of the tetranucleotide and pentanucleotide repeat motifs are organism specific. In general, repeats are short and CG-rich repeats are present in Archaea having a CG-rich genome. Among the 19 Archaea, SSR density was not correlated with genome size or with optimum growth temperature. Pentanucleotide density had an inverse correlation with the CG content of the genome.

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