Evolutionary dynamics of autopolyploids in natural populations: the case of Turnera sidoides complex / Dinámica evolutiva de autopoliploides en poblaciones naturales: el caso del complejo Turnera sidoides

ABSTRACT Turnera sidoides (x=7) is one of the few well-studied South American autopolyploid complexes. Since polyploidy has played a prominent role within this complex, ongoing studies in T. sidoides focus on understanding the mechanisms involved in the origin and the establishment of polyploids using integrative approaches. This paper synthesises the results of more than 20 years of research on this topic. Cytogenetics analysis provided evidences for the production of unreduced male and female gametes, supporting the hypothesis of bilateral sexual polyploidization as the mechanism of origin of polyploids in T. sidoides. The finding of viable triploids suggested that unilateral sexual polyploidization could also be an important mechanism for the origin of tetraploids in T. sidoides. The occurrence of plants continuously forming many unreduced gametes would play a key role in the establishment of neopolyploids in natural populations. Also, the higher number of propagules that tetraploids contribute to subsequent generations, the ability to multiply asexually by rhizomes, and the occurrence of occasional cases of self-compatibility and successful illegitimate crosses in polyploids increase the likelihood that a low frequency of neopolyploids can be maintained in natural populations of T. sidoides. In addition, integration of cytogeographic and genetic divergence data together with past niche modelling provided further insights supporting the hypothesis that historical climatic and geomorphological events provided favourable conditions for the establishment of autopolyploids, with the wider distribution of tetraploids of T. sidoides being the result of their range expansion.

RESUMEN Turnera sidoides (x=7) es uno de los pocos complejos autopoliploides sudamericanos bien estudiados. Como la poliploidía ha tenido un papel destacado en el complejo, los estudios en curso en T. sidoides se centraron en la comprensión de los mecanismos implicados en el origen y el establecimiento de los poliploides mediante diferentes enfoques. En este trabajo se sintetizan los resultados de más de 20 años de investigación sobre este tema. El análisis citogenético proporcionó evidencias de la producción de gametos masculinos y femeninos no reducidos, sustentando la hipótesis de la poliploidización sexual bilateral como mecanismo de origen de los poliploides en T. sidoides. Sin embargo, el hallazgo de triploides fértiles sugirió que la poliploidización sexual unilateral también sería un mecanismo importante de origen de tetraploides en T. sidoides. La ocurrencia de plantas que forman continuamente gametos no reducidos desempeñaría un papel clave en el establecimiento de neopoliploides. Además, el mayor número de propágulos que los tetraploides aportan a las siguientes generaciones, la capacidad de multiplicación asexual por rizomas y los casos ocasionales de autocompatibilidad y cruzamientos ilegítimos exitosos aumentarían la probabilidad de que se mantenga una baja frecuencia de neopoliploides en las poblaciones naturales de T. sidoides. Asimismo, la integración de datos citogeográficos y de divergencia genética junto con el modelado de nicho en el pasado aportó información que sustenta la hipótesis de que los eventos climáticos y geomorfológicos históricos proporcionaron las condiciones favorables para el establecimiento y expansión de los tetraploides de T. sidoides.

Lung (agricultural/rural).

Industrialization of farming, animal raising, and forestry has added chemical and mechanical hazards that need to be recognized and prevented. Lung disease among farmworkers can result from a wide variety of hazardous exposures, which include organic dusts, allergens, chemicals, toxic gases, and infectious agents. In addition to nonspecific symptoms of mucous membrane irritation, farmworkers can experience occupational asthma or bronchitis, organic dust toxic syndrome, hypersensitivity pneumonitis, silo filler's disease (toxic hemorrhagic pulmonary edema), and neuromuscular respiratory failure. At risk are farmworkers and those involved in the processing, stocking, transportation, handling, and inspection of unprocessed agricultural, animal, and forestry products; veterinarians; gardeners; game, river, and forest keepers; persons involved in building, supplying, or servicing farm operations; and residents of rural communities. Worker education on the risks of environmental exposures, adherence to safety regulations, and increased knowledge of the cause and prevention of environmental diseases will reduce their prevalence and their adverse human and animal health and socioeconomic effects.

Role of chest physicians in detection and treatment of occupational and environmental respiratory disease. A practice survey.

A survey of American College of Chest Physicians (ACCP) members was conducted to determine their degree of involvement in the diagnosis and prevention of occupational and environmental respiratory disease (OERD). Although the response rate was relatively low, the results are likely to be representative. Calculations based on the data estimate that in the prior year, chest physicians on the average saw 15 patients with OERD caused by work, 13 worsened by work, and 28 affected by the home environment. Asthma appears to be a more common occupational or environmental concern than pulmonary fibrosis. Chest physicians clearly perceived a need for more education in OERD. The survey also demonstrated that although many chest physicians perform routine industrial surveillance testing, it is often done without using standardized methods. Furthermore, chest physicians are actively involved with medical/legal aspects of OERD. Overall, the survey documents the role of chest physicians in the area of OERD and emphasizes significant educational needs.

Toxic gas inhalation.

Severe toxic fume inhalations, usually accidental due to human error or equipment failure, can result in immediate death from asphyxia or cause mild to severe respiratory distress from acute upper airways inflammation, delayed pulmonary edema, respiratory muscle dysfunction, or a combination of illnesses. Most patients are expected to survive and recover with little or no residual dysfunction regardless of the severity of the initial event. However, in some cases disabling long-term sequelae, eg, bronchiectasis, chronic airflow obstruction, bronchial hyperreactivity, asthma-like disease (reactive airways dysfunction syndrome), bronchiolitis obliterans, or residual psychophysiologic dyspnea, can occur. Therapy of the respiratory effects of irritant gases should follow the general principles used for the treatment of upper and lower airway obstruction, noncardiogenic pulmonary edema, and hemorrhagic pneumonitis while spontaneous healing and recovery occurs, because no specific therapy is available for direct chemical pulmonary injury. Corticosteroids are frequently used and recommended, but their efficacy in altering the course and outcome of respiratory injury has not yet been properly documented.

Hazardous exposure and lung disease among farm workers.

Industrialization of farming, animal raising, and forestry has added new chemical and mechanical hazards that need to be recognized and prevented. Lung disease among farm workers can result from a wide variety of hazardous exposures that include organic dusts, chemicals, and toxic gases. In addition to nonspecific symptoms of mucous membrane irritation, farm workers can develop occupational asthma or bronchitis, organic dust toxic syndrome, hypersensitivity pneumonitis, silo filler's disease (toxic hemorrhagic pulmonary edema), and neuromuscular respiratory failure.

Pulmonary reaction to upper mantle radiation therapy for Hodgkin's disease.

To study the effects of upper mantle radiation therapy on pulmonary function, forced expiratory volume in one second (FEV1), vital capacity (VC), inspiratory capacity (IC), diffusing capacity for CO (DLCO) and diffusion per unit of alveolar volume (DL/VA were determined in 28 patients with Hodgkin's disease, stages 1--3, before therapy and at regular intervals thereafter. Within the first year of follow-up there were significant declines in DLCO, VC, and IC, whereas there were no significant changes in FEV1 or DL/VA. DLCO showed the greatest decline in the largest number of subjects (22/28). Eleven of the 22 had 20 to 60 percent decline of DLCO from baseline. The maximum mean decline in DLCO was -12.7 +/- 3 percent at the 87th +/- 3 days from initiation of therapy postradiation sustained through the 150th day and improving to pretreatment value (+/- 5 percent) by the 8th to 12th month. The changes in DLCO seemed to be independent of the radiation dose ranges evaluated, clinically apparent intrathoracic lymphoma, postradiation radiographic abnormalities and respiratory symptoms. We concluded that impairment in diffusing capacity and loss of vital capacity will develop in most patients receiving upper mantle radiation therapy, indicating that pulmonary reaction occurs despite lung shielding. The functional losses were prolonged and occasionally severe, but were transient and subclinical in most but not all cases. A case of fatal radiation pneumonitis affecting the lung beyond the field of irradiation is reported.