Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Physiological quality and biochemical changes in Caesalpinia peltophoroides Benth. (sibipiruna) seeds during storage

O presente estudo foi realizado no Laboratório de Análise de Sementes Florestais (LASF) do Departamento de Engenharia Florestal da Universidade Federal de Viçosa, com o objetivo de avaliar algumas alterações fisiológicas e bioquímicas em sementes de Caesalpinia peltophoroides Benth. (sibipiruna) durante o armazenamento, estabelecendo relações entre essas alterações e a perda de viabilidade e vigor. Para tanto, utilizaram-se sementes colhidas em Viçosa – MG, entre julho e agosto de 2002, que foram armazenadas a 5° e UR 70% e 20° e UR 62%. Foram C C retiradas amostras de sementes para a realização dos testes de germinação, condutividade elétrica, envelhecimento acelerado e determinação dos teores de água. Os teores de amido e de ácidos graxos foram quantificados nos cotilédones e no eixo embrionário. As análises foram realizadas logo após a colheita e aos 60, 120, 180 e 220 dias desde o armazenamento. As porcentagens de germinação das sementes mantidas a 5 e 20° foram C reduzidas a partir de 220 e 120 dias, respectivamente. O índice de velocidade de germinação (IVG) decresceu de maneira similar. A condutividade elétrica permaneceu constante nas sementes armazenadas a 5° e aumentou nas que permaneceram a 20° Os teores de amido C C. sofreram reduções significativas em as ambas temperaturas, nos cotilédones, mas não no eixo embrionário. Os teores de ácidos graxos saturados e insaturados do eixo embrionário e dos cotilédones tiveram alterações significativas em ambas temperaturas, com exceção do ácido oléico, que se manteve constante nos cotilédones e no eixo embrionário das sementes mantidas a 5 e 20° C, respectivamente. O envelhecimento acelerado nos períodos de 24, 48 e 72 horas detectou redução significativa na qualidade das sementes em ambos os ambientes de armazenamento. Os resultados em conjunto mostram que ocorreram alterações nas sementes, com redução mais acentuada da viabilidade e do vigor nas sementes armazenadas a 20° do que naquelas mantidas a 5° C C, estando as alterações provavelmente associadas às modificações nos teores de ácidos graxos.This study was carried out at the Laboratory for Analysis of Forest Seeds (LASF) of the Forest Engineering Department, Universidade Federal de Viçosa, in order to evaluate the physiological and biochemical alterations in Caesalpinia peltophoroides Benth. (sibipiruna) seeds during storage. To establish relationships between these changes and the loss of viability and vigor, seeds were collected in Viçosa, State of Minas Gerais, Brazil, between July and August 2002. The seeds were stored at 5° and UR 70%, and 20° C C and UR 62%. Seeds samples were taken to evaluate germination, electric conductivity, and accelerated senescence, as well as water contents. Starch and fatty acid contents were quantified in the cotyledons and the embryonic axis. The analyses were carried out immediately after harvesting and also after 60, 120, 180, and 220 days of storage. Germination percentages of the seeds stored at 5 and 20° sank after 220 and 120 days, respectively. The C germination speed index (IVG) decreased similarly. The electric conductivity remained constant in the stored seeds at 5° and increased in those stored C at 20° C. Starch contents underwent significant reductions at both temperatures in the cotyledons, but not in the embryonic axis. The contents of saturated and unsaturated fatty acids of the embryonic axis and the cotyledons presented significant alterations in both temperatures, with exception of the oleic acid, which remained stable in the cotyledons and the embryonic axis of the seeds stored at 5 and 20° respectively. A significant C, reduction of the seed quality was detected by accelerated senescence after 24, 48, and 72 hours for both storage conditions. Combined results show that alterations took place in the seeds, with a clearer reduction of viability and vigor in the seeds stored at 20° than in those stored at 5° The alterations C C. were probably associated to modifications of the fatty acid contents.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Influence of the enzymes α-galactosidase and poligalacturonase in the Dalbergia nigra seed germination (Leguminoseae-Papilonoidea)

Este trabalho teve como objetivos: i) quantificar e caracterizar as enzimas α-galactosidase e poligalacturonase (PG) em sementes de D. nigra, ii) verificar a composição e a alteração dos açúcares que compõem a parede celular e a fração péctica dos tegumentos das sementes durante a germinação. As sementes foram colocadas para embeber em água por 168 horas, sendo retiradas amostras para a caracterização bioquímica e cinética da enzima. A atividade da enzima α-galactosidase aumentou com a embebição nos dois compartimentos, embora não estivesse presente inicialmente no eixo embrionário de sementes secas. O pH de máxima atividade foi de 5,5 para ambos os compartimentos. A temperatura que mais estimulou a atividade nos cotilédones foi de 50 °C e de 50 a 60 °C no eixo embrionário. A enzima mostrou-se termotolerante, mas não foi possível determinar a meia-vida na temperatura de 40 °C, no período de 10 horas. A atividade da α-galactosidase foi inibida por β-mercaptoetanol e CuSO4 em ambos os compartimentos. A lactose e o cloreto de sódio estimularam a atividade tanto nos cotilédones como no eixo embrionário. Os valores de KM para o eixo embrionário e cotilédones foram de 0,239 e 0,228 mM, respectivamente. A enzima α-galactosidase está presente nas sementes de Dalbergia nigra e sua atividade específica aumenta durante o período de germinação. A atividade da PG foi detectada a partir do primeiro dia de embebição, tanto nos cotilédones como no eixo embrionário. A atividade máxima nos cotilédones foi detectada no segundo dia e, no eixo, no sexto dia de embebição. A variação no teor de proteínas foi significativa ao longo do tempo nos cotilédones e no eixo. A atividade de PG foi máxima nas temperaturas de 60°C nos cotilédones e de 55 a 60 °C no eixo embrionário. O pH 4,0 foi o de maior atividade da enzima para ambos os compartimentos. O KM foi de 5,08 e de 4,39 mM para os cotilédones e o eixo, respectivamente. O Vmax foi de 0,026 mM min-1para cotilédones e de 0,024 mM min-1 para eixo embrionário. Nos tegumentos, a atividade específica da PG foi máxima no terceiro dia. O teor de proteína se reduziu a partir da embebição. A atividade de PG foi máxima nas temperaturas de 40 a 50 °C. O pH de maior atividade da enzima ficou na faixa de 3 a 7. O KM e o Vmax foram de 1,34 mM e 0,012 μmol min-1, respectivamente. Verificou-se que a galactose é o principal componente da pectina, seguida pela manose. Na parede celular, o principal componente foi a arabinose, seguida pela xilose. Com base nos resultados, conclui-se que as enzimas α-galactosidase e PG atuam durante a germinação das sementes de Dalbergia nigra.This work aimed to study the enzymes α-galactosidase and polygalacturonase and to verify the composition and the alteration of the cell wall sugars and the pectic component in the teguments of D. nigra seeds during the germination. The seeds were submitted to water imbibition for 168 hours. Samples of seeds were taken for the biochemical and kinetic characterization of the enzymes. Activity of the enzyme α- galactosidase increased with the imbibition, although it was not present initially in the embryonic axis of dry seeds. The maximum activity was obtained at ph 5.5 to both compartments. In the cotyledon the activity of the enzyme was higher at temperature of 50°C, and in the embryonic axis it was between 50 and 60°C. The enzyme was tolerant to temperature, but it was not possible to determine its half-life at the temperature of 40 °C, in the period of 10 hours. The activity of the α-galactosidase was inhibited by β- mercaptoethanol and CuSO4 in both compartments, the lactose and the sodium chloride stimulated the activity in the cotyledons and in the embryonic axis. The KM values for the embryonic axis and cotyledons were respectively 0,239 and 0,228 mM. The α-galactosidase is present in the seeds of Dalbergia nigra and its specific activity increases during the germination period. Activity of PG was detected from the first day of imbibition, in the cotyledons and in the embryonic axis. Maximum activity in the cotyledons was detected in the second day and in the axis in the sixth day of soaking. The variation in the proteins content was significant along the time in the cotyledons and in the axis. The activity of PG was maximal at the temperature of 60°C in the cotyledons and in the embryonic axis the maximal activity was observed in a range of temperatures from 55 to 60 °C. The activity of the enzyme was higher at pH 4,0 to all compartments. The KM was 5,08 and 4,39 mM for the cotyledons and axis, respectively. Vmax was 0,026 mM min-1 in the cotyledon enzyme and 0,024 mM min-1 for embryonic axis enzyme. In the teguments, activity of PG was maximal in the third day. The protein content reduced along the imbibition period. The activity of PG was maximal temperatures ranging from 40 to 50 °C. The pH of higher activity to this enzyme was obtained from pH 3 until pH 7,0. The KM and Vmax were 1,34 mM and 0,012 µmol min-1, respectively. It was verified that the galactose is the main component of the pectin, followed by the mannose. Arabinose was the most abundant component in the cell wall, followed by xylose. Based on the results, we can conclude that the enzymes α-galactosidase and PG are acting during the germination of Dalbergia nigra seeds.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Histochemical and ultrastructural study of Caesalpinia peltophoroides Benth. (Leguminosae-Caesalpinoideae) seeds

The objective of this work was to correlate data on light microscopy observations through histochemical analysis and polarized light techniques and investigations in transmission electron microscopy (TEM) to characterize the reserve materials in C. peltophoroides Benth. (Leguminosae-Caesalpinoideae) cotyledons, popularly known as "sibipiruna", a tropical tree species with wide distribution in Brazil. The cotyledon mesophyll, especially in the abaxial face, is rich in unsaturated neutral lipids contained in numerous lipid bodies dispersed in the cytoplasm. Proteins, more concentrated in the adaxial face of the cotyledons, occur in all the mesophyll and are stored in protein bodies containing globoids, with variable number and size, responsible for accumulation of mineral reserves. Calcium oxalate druses have distribution restricted to the cotyledons adaxial face and are associated with protein bodies. Starch, also distributed all over the cotyledon mesophyll, occurs in small amounts in plastids with developed lamellar system. Secretory cavities rich in phenolic compounds occur among procambial strands