Forest type modulates mammalian responses to megafires.

Although considered an evolutionary force responsible for shaping ecosystems and biodiversity, fires' natural cycle is being altered by human activities, increasing the odds of destructive megafire events. Here, we show that forest type modulates the responses of terrestrial mammals, from species to assemblage level, to a catastrophic megafire in the Brazilian Pantanal. We unraveled that mammalian richness was higher 1 year after fire passage compared to a pre-fire condition, which can be attributed to habitat modification caused by wildfires, attracting herbivores and open-area tolerant species. We observed changes in assemblage composition between burned/unburned sites, but no difference in mammalian richness or relative abundance. However, by partitioning the effects of burned area proportion per forest type (monospecific vs. polyspecific), we detected differential responses of mammals at several levels of organization, with pronounced declines in species richness and relative abundance in monospecific forests. Eighty-six percent of the species presented moderate to strong negative effects on their relative abundance, with an overall strong negative effect for the entire assemblage. Wildfires are predicted to be more frequent with climate and land use change, and if events analogous to Pantanal-2020 become recurrent, they might trigger regional beta diversity change, benefitting open-area tolerant species.

Historical survey of research related to fire management and fauna conservation in the world and in Brazil / Levantamento de artigos científicos relacionados à gestão do fogo e a conservação da fauna no mundo e no Brasil

Abstract: Fire is a key ecological factor affecting biodiversity structure and composition. Fires' effects on biodiversity can be beneficial or harmful depending on how, where, when, and why they occur. The impacts of fire on fauna vary according to species ecology and the fire regime. To understand the research effort relating fire, fauna, and mammals, we surveyed papers published in World and in Brazil. Only 5% of the publications between 1970 and 2019 with fire subject dealt with fauna and 0.5% with mammal. For Brazil, we obtained 7% of papers for fauna and 3% for mammal. The Brazilian Biome with more papers was Cerrado, followed by Atlantic Forest, Amazon, Pampas, Caatinga and Pantanal. The United States of America and Australia stand out as protagonists in their continents with the largest papers number. The volume of research is related to investment in Research and Development and to occurrence of fires. The slope of temporal trend shows the terms related to wildfire have more papers than prescribed burn and there is less interest in fauna and mammal research. It is necessary to form research groups with these themes as research lines and intensify research relating fire ecology and mammals. There is yet no unified understanding of how fire may influence animal diversity and how it influences the vegetative structure and subsequently the resources which wildlife rely on. We consider this information is essential to establish efficient conservation policies.

Resumo: O fogo é um fator ecológico que pode determinar os padrões de diversidade, estrutura e composição da biodiversidade. Assim, o fogo pode ser favorável ou prejudicial, dependendo de como, onde, quando e porquê ocorre. Os impactos do fogo na fauna variam de acordo com a ecologia das espécies e o regime de fogo. Levantamos a quantidade de artigos publicados no mundo e no Brasil para entender o esforço de pesquisa que relaciona fogo, fauna e mamíferos. Apenas 5% das publicações entre 1970 e 2019 com o assunto fogo tratam de fauna e 0,5% de mamíferos. Para o Brasil, obtivemos 7% dos artigos para fauna e 3% para mamíferos. O bioma brasileiro com mais artigos foi o Cerrado, seguido por Mata Atlântica, Amazônia, Pampa, Caatinga e Pantanal. Os países que se destacam como protagonistas em seus continentes, com maior número de publicações, são Estados Unidos da América e Austrália. O volume de pesquisas está relacionado aos investimentos em pesquisa e desenvolvimento e à ocorrência de incêndios florestais. A regressão linear demonstra que os termos relacionados a incêndios florestais têm mais publicações do que os relacionados a queimas prescritas e há menos interesse em pesquisas relacionadas a fauna e a mamíferos. Diante disso, acreditamos ser necessário formar grupos de pesquisa nesses temas e intensificar os estudos relacionando ecologia do fogo e mamíferos. Ainda não existe um entendimento único sobre a influência do fogo na diversidade de animais e na estrutura da vegetação e, subsequentemente, nos recursos dos quais a vida selvagem depende. Consideramos que essas informações são essenciais para estabelecer políticas públicas de conservação mais eficientes.

Xylitol dehydrogenase from Candida tropicalis: molecular cloning of the gene and structural analysis of the protein.

Yeasts can metabolize xylose by the action of two key enzymes: xylose reductase and xylitol dehydrogenase. In this work, we present data concerning the cloning of the XYL2 gene encoding xylitol dehydrogenase from the yeast Candida tropicalis. The gene is present as a single copy in the genome and is controlled at the transcriptional level by the presence of the inducer xylose. XYL2 was functionally tested by heterologous expression in Saccharomyces cerevisiae to develop a yeast strain capable of producing ethanol from xylose. Structural analysis of C. tropicalis xylitol dehydrogenase, Xyl2, suggests that it is a member of the medium-chain dehydrogenase (MDR) family. This is supported by the presence of the amino acid signature [GHE]xx[G]xxxxx[G]xx[V] in its primary sequence and a typical alcohol dehydrogenase Rossmann fold pattern composed by NAD(+) and zinc ion binding domains.

Effect of acetic acid present in bagasse hydrolysate on the activities of xylose reductase and xylitol dehydrogenase in Candida guilliermondii.

The first two steps in xylose metabolism are catalyzed by NAD(P)H-dependent xylose reductase (XR) (EC 1.1.1.21) and NAD(P)-dependent xylitol dehydrogenase (XDH) (EC 1.1.1.9), which lead to xylose-->xylitol-->xylulose conversion. Xylitol has high commercial value, due to its sweetening and anticariogenic properties, as well as several clinical applications. The acid hydrolysis of sugarcane bagasse allows the separation of a xylose-rich hemicellulosic fraction that can be used as a substrate for Candida guilliermondii to produce xylitol. However, the hydrolysate contains acetic acid, an inhibitor of microbial metabolism. In this study, the effect of acetic acid on the activities of XR and XDH and on xylitol formation by C. guilliermondii were studied. For this purpose, fermentations were carried out in bagasse hydrolysate and in synthetic medium. The activities of XR and XDH were higher in the medium containing acetic acid than in control medium. Moreover, none of the fermentative parameters were significantly altered during cell culture. It was concluded that acetic acid does not interfere with xylitol formation since the increase in XR activity is proportional to XDH activity, leading to a greater production of xylitol and its subsequent conversion to xylulose.

Reclassification of Candida guilliermondii FTI 20037 as Candida tropicalis based on molecular phylogenetic analysis

As leveduras do gênero Candida possuem tanto importância clínica como diversas aplicações industriais, principalmente na indústria de alimentos. A levedura Candida guilliermondii FTI 20037 tem sido exaustivamente estudada pois pretende-se utilizá-la no estabelecimento de um processo biotecnológico para a produção de xilitol. O objetivo deste trabalho foi verificar a classificação taxonômica desta levedura por análise de sequências do rDNA e do gene xyl1. Fragmentos correspondentes a estas regiões foram amplificados por PCR e a análise destas sequências por BLAST revelou alta identidade com sequências correspondentes de Candida tropicalis. Estes resultados nos levam a propor que C. guilliermondii FTI 20037 deva ser reclassificada como C. tropicalis.

Reclassification of Candida guilliermondii FTI 20037 as Candida tropicalis based on molecular phylogenetic analysis

Yeasts of the genus Candida are of clinical importance and also have many industrial applications, mainly in the food industry. The yeast Candida guilliermondii FTI 20037 has been extensively studied in order to establish a biotechnological process for the production of xylitol. The goal of this study was to verify the taxonomic classification of this strain based on the analysis of rDNA sequences and the xyl1 gene. DNA fragments from these sequences were amplified by PCR and BLAST analysis revealed strong identity with the corresponding sequences from Candida tropicalis. Based on these results, we propose that C. guilliermondii FTI 20037 must be reclassified as C. tropicalis.

As leveduras do gênero Candida possuem tanto importância clínica como diversas aplicações industriais, principalmente na indústria de alimentos. A levedura Candida guilliermondii FTI 20037 tem sido exaustivamente estudada pois pretende-se utilizá-la no estabelecimento de um processo biotecnológico para a produção de xilitol. O objetivo deste trabalho foi verificar a classificação taxonômica desta levedura por análise de sequências do rDNA e do gene xyl1. Fragmentos correspondentes a estas regiões foram amplificados por PCR e a análise destas sequências por BLAST revelou alta identidade com sequências correspondentes de Candida tropicalis. Estes resultados nos levam a propor que C. guilliermondii FTI 20037 deva ser reclassificada como C. tropicalis.