ABSTRACT
Pneumocystis, an important opportunistic fungal pathogen that parasitizes in multiple mammalian lungs, may cause life-threatening Pneumocystis pneumonia (PCP) and even death among immunocompromised individuals. With the rapid development of high-throughput sequencing and multi-omics technologies, systematic comparative analyses of genome, transcriptome, and whole-genome sequencing results demonstrate that Pneumocystis is a type of obligate biotrophic fungi, and requires obtaining nutrition from hosts. In addition, sexual reproduction is an essential process for Pneumocystis survival, production and transmission, and asexual reproduction facilitates Pneumocystis survival, which provides new insights into understanding of the whole developmental process of Pneumocystis in the host lung and inter-host transmission of Pneumocystis. This review summarizes the advances in the reproduction mode of Pneumocystis and underlying mechanisms, which provides insights into prevention and treatment of PCP, notably for the prophylaxis against nosocomial transmission of PCP.
ABSTRACT
Obtaining juvenile material may favor the clonal propagation of Brazil nut, Bertholletia excelsa. We aimed to assess the emission of epicormic shoots on detached branches of Brazil nut trees as a function of the mother tree and branch diameter, in order to provide juvenile material for use in clonal multiplication. The experimental design was completely randomized in a 6 (mother trees) x 3 (stem diameter: < 20 20-40 and 40-80 mm) factorial design, with four replicates. Every five days the number of shoots emitted was counted and the sprouting speed index and average sprouting time were calculated. The number of epicormic shoots and the sprouting speed index were dependent on the interaction between mother tree and branch diameter. Branches with larger diameter (20-40 and 40-80 mm) showed higher potential for obtaining propagules for use in Brazil nut clonal multiplication (cutting, grafting and in vitro cultivation). (AU)
Subject(s)
Reproduction, Asexual , Forestry , Lecythidaceae , BertholletiaABSTRACT
Apomixis or asexual reproduction through seeds occurs in about 400 species of flowering plants producing geneticallyuniform progeny. During apomixis, meiosis is bypassed and embryos develop by parthenogenesis. However, the endospermcould form either autonomously without fertilization or sexually, depending on the plant species. Most probably, aheterochronic expression of sexually expressed genes is one of the reason that causes apomixis. A better understanding ofthe genetic components regulating apomixis is important for developmental and evolutionary studies and also for engineering apomixis traits into crop plants that may realize a possibility to propagate hybrid vigor in a range of subsequentgenerations.
ABSTRACT
Los cultivos realizados con S. lacustris demostraron que la temperatura juega un papel de importancia en la tasa de la reproducción, en cuanto al número de zooides producido por individuo así como también al tamaño alcanzado por los mismos. Por otro lado, regularía la tasa de crecimiento y la reproducción sexual, dando lugar a la madurez de los individuos cuando aumenta la temperatura. El tiempo de vida promedio de los individuos inmaduros se estimó en 15 días, siendo este valor independiente de la temperatura utilizada en los cultivos. Los individuos maduros vivieron en promedio 37 días. La supervivencia en S. lacustris fue decreciendo gradualmente, según una curva de tipo lll. La expectativa de vida presentó su pico a la edad de 16 días y se mantuvo aproximadamente constante hasta una edad de 28 días a partir de la cual fue decreciendo en forma persistente hasta la última edad alcanzada. Se estimó el crecimiento individual, según la ecuación de von Bertalanffy, para los organismos mantenidos a 23 ± 2 ºC y a 14 ± 1 ºC. En aquellos individuos cultivados a mayor temperatura se registró una mayor talla, aunque su tasa de crecimiento fue menor que la de los individuos mantenidos a 14 ºC.
The experiments carried out with S. lacustris showed that the temperature plays a role of importance in the rate of asexual reproduction, as for the number of zooids produced by individual, as well as to the size reached by them. On the other hand, it would regulate the rate of growth and the sexual reproduction, giving place to the maturity of the individuals when temperature increases. The life time of the immature individuals was estimated in 15 days, being this independent of the temperature used in the cultures. The mature individuals lived on the average 37 days. The survival in S. lacustris was falling gradually, following a curve of type lll. Life expectancy presented its major value at the age of 16 days and stayed approximately constant up to an age of 28 days, after then falled persistently until the last reached age. The individual growth according to von Bertalanffy equation, was estimated for the organisms maintained at 23 ± 2 ºC and at 14 ± 1 ºC. Those individuals cultivated at higher temperature attained a bigger size, although their rate of growth was smaller than those maintained at 14 ºC.