RESUMEN
ABSTRACT The phenology of vascular epiphytes, which account for about 10 % of the world's flowering plants and perform important ecological functions, has been just partially explored. Since phenology is a key tool for the management and conservation of species, the objective of this review was to synthesize the information published so far about the phenology of vascular epiphytes, detect gaps of knowledge, and suggest future lines of investigation to understand the underlying mechanisms. We conducted an online search for articles in Google Scholar and in the ISI Web of Science database from 1800 to 2020, with different combinations of keywords. 107 studies addressing the phenology of different holoepiphyte species were found; 88 % of the studies were performed in the Neotropic, especially in tropical and subtropical wet forests. The phenology of only ca. 2 % (418 spp.) of all reported holoepiphyte species has been explored. There is a bias toward the study of the flowering and fruiting phenology in members of the Orchidaceae (192 spp.) and Bromeliaceae (124 spp.) families. In general, the vegetative and reproductive phenology of epiphytes tends to be seasonal; however, there is a huge gap in our understanding of the proximate and ultimate factors involved. Future research should explicitly focus on studying those factors.
RESUMEN Las epífitas vasculares, que representan cerca del 10 % de la flora vascular y cumplen funciones ecológicas importantes, se han explorado poco desde el punto de vista fenológico. Dado que la fenología es una herramienta clave para el manejo y conservación de especies, el objetivo de este trabajo fue sintetizar la información publicada, detectar vacíos de conocimiento y sugerir líneas de investigación que permitan entender los mecanismos que regulan la fenología de este grupo. Se realizó una búsqueda de artículos en Google Académico y en la base de datos ISI Web of Science desde 1800 a 2020, con diferentes combinaciones de palabras clave. Se encontraron 107 estudios que abordan la fenología de especies holoepífitas, el 88 % de estos estudios se realizaron en el Neotrópico, principalmente en bosques lluviosos tropicales y subtropicales. Solamente se ha estudiado la fenología de ca. 2 % (418 spp.) del total de especies de holoepífitas reportadas; los trabajos se han enfocado principalmente en estudiar la floración y fructificación de miembros de Orchidaceae (192 spp.) y Bromeliaceae (124 spp.). La fenología vegetativa y reproductiva de las epífitas tiende a ser estacional. Sin embargo, existe un vacío enorme de los factores próximos y últimos implicados; los futuros estudios pueden enfocarse a elucidar qué factores detonan la fenología de epífitas vasculares.
RESUMEN
BACKGROUND: The muskrat is a seasonal breeder. Males secrete musk to attract females during the breeding season. The testosterone binding to the androgen receptor (AR) in musk glands of muskrat may play an important role conducting the musk secretion process. METHODS: The musk gland, testis and blood samples of musk rats are collected in both breeding and non-breeding seasons. Some part of the samples are kept in liquid nitrogen for transcriptome analysis and Western blotting test. Some part of the samples are kept in 70% alcohol for histology experiment, blood samples are kept at -20 °C for the serum testosterone measurement experiment. RESULTS: This study demonstrates that the quantity of secreted musk, the volume of the musk glands, the diameter of the gland cells and AR expression are all higher during the breeding season than at other times (p < 0.01). StAR, P450scc and 3ß-HSD expression in the Leydig cells of the testis were also higher during this season, as was serum testosterone. AR was also observed in the gland cells of two other musk-secreting animals, the musk deer and small Indian civet, in their musk glands. These results suggest that the testes and musk glands co-develop seasonally. CONCLUSION: The musk glands' seasonal development and musk secretion are regulated by the testes, and testosterone plays an important role in the seasonal development of musk glands.