Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications 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, 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

Desenvolvimento testicular, espermatogênese e concentrações hormonais em touros Angus Testicular development, spermatogenesis and hormonal concentrations in Angus bulls

Este estudo foi realizado com a finalidade de avaliar a evolução das secreções hormonais e do epitélio seminífero em touros da raça Angus de 10 a 38 semanas de idade. Foram castrados 1 a 5 animais em intervalos de quatro semanas (total de 25 touros) para coleta de amostras do parênquima testicular e do plasma sanguíneo. As variáveis relacionadas ao crescimento testicular, aos aspectos quantitativos da espermatogênese e aos níveis hormonais foram transformadas em logaritmo e avaliadas por meio de análise de variância. O diâmetro dos testículos e túbulos seminíferos e o peso testicular apresentaram variações mais acentuadas após 26 semanas de idade. A porcentagem do parênquima testicular ocupado pelos túbulos seminíferos aumentou de 49,3 para 75,2% durante o experimento. A maioria dos túbulos (>90%) apresentou-se com células de Sertoli somente entre 10 e 14 semanas, mas na 18ª (13,8&plusmn;1,7%) e 22ª semanas (19&plusmn;1%), o número de túbulos com gonócitos e espermatogônias aumentou em relação às semanas iniciais. Espermatogônias intermediárias e B predominaram na 26ª semana (24,5&plusmn;8,2%) e a porcentagem de túbulos com espermatócitos foi mais elevada na 30ª semana (42,3&plusmn;9,9%). Espermátides arredondadas foram detectadas partir da 26ª semana e, na 38ª semana, 62,3&plusmn;1,5% dos túbulos seminíferos continham espermátides alongadas ou maduras. As variações mais acentuadas no crescimento testicular e, principalmente, no peso testicular após as 26 semanas coincidiram com o estabelecimento da meiose, com as alterações morfológicas do núcleo e nucléolo das células de Sertoli (indicativos do processo de diferenciação das mesmas), com os níveis reduzidos de androstenediona e os incrementos significativos de testosterona e estradiol 17beta. As associações entre o crescimento testicular e os níveis de FSH e LH na circulação periférica foram menos evidentes.<br>This study aimed to evaluate changes in hormone secretion and in seminiferous epithelium of Angus bulls between 10 and 38 weeks of age. Samples of testicular parenchyma and blood were collected from 25 animals castrated in 4 week intervals. Traits associated to testicular development and quantitative aspects of spermatogenesis and hormonal concentrations were transformed by logarithm before analyses of variance. Changes in testis and seminiferous tubule diameter and testis weight were more pronounced after 26 weeks of age. The percentage of testicular parenchyma occupied by seminiferous tubules increased from 49.3 to 75.2% from 10 to 38 weeks. Most tubules (>90%) had only Sertoli cells at 10 and 14 weeks, but the number of tubules with gonocytes and A spermatogonia increased at 18 (13.8&plusmn;1.7%) and 22 weeks (19&plusmn;1%). Tubules with B and intermediate spermatogonia became predominant at 26 weeks (24.5&plusmn;8.2%) and those with spermatocytes as the most advanced germ cell type were more evident at 30 weeks (42.3&plusmn;9.9%). Round spermatids were detected at 26 weeks and at 38 weeks of age, 62.3&plusmn;1.5% of all tubules had either elongate or mature spermatids. Variations in testis growth (specially testis weight) after 26 weeks were coincident with the establishment of meiosis in the seminiferous tubules, morphological alterations in nucleus and nucleolus of the Sertoli cells (indicators of Sertoli cell differentiation), lower levels of androstenedione and significant increases in testosterone and estradiol 17beta. Associations between testis development and concentrations of FSH and LH were less evident