Transcriptomic analysis supports similar functional roles for the two thymuses of the tammar wallaby

Background: The thymus plays a critical role in the development and maturation of T-cells. Humans have a single thoracic thymus and presence of a second thymus is considered an anomaly. However, many vertebrates have multiple thymuses. The tammar wallaby has two thymuses: a thoracic thymus (typically found in all mammals) and a dominant cervical thymus. Researchers have known about the presence of the two wallaby thymuses since the 1800s, but no genome-wide research has been carried out into possible functional differences between the two thymic tissues. Here, we used pyrosequencing to compare the transcriptomes of a cervical and thoracic thymus from a single 178 day old tammar wallaby.Results: We show that both the tammar thoracic and the cervical thymuses displayed gene expression profiles consistent with roles in T-cell development. Both thymuses expressed genes that mediate distinct phases of T-cells differentiation, including the initial commitment of blood stem cells to the T-lineage, the generation of T-cell receptor diversity and development of thymic epithelial cells. Crucial immune genes, such as chemokines were also present. Comparable patterns of expression of non-coding RNAs were seen. 67 genes differentially expressed between the two thymuses were detected, and the possible significance of these results are discussed.Conclusion: This is the first study comparing the transcriptomes of two thymuses from a single individual. Our finding supports that both thymuses are functionally equivalent and drive T-cell development. These results are an important first step in the understanding of the genetic processes that govern marsupial immunity, and also allow us to begin to trace the evolution of the mammalian immune system

Conservation through education

The way to conservation is through education. People of all ages everywhere are learning how to make wise use of natural resources to ultimately ben- efit and sustain future generations but clear goals, objectives and analogies are needed to reinforce the message. Conservation education initiatives can be compared to production of a food crop. A crop plant must first be selected to suit the growing environment then the fields prepared for planting. After planting, the growing plants must be cared for. Only after a successful harvest can the profit be realized. The way to conservation is through education. People of all ages everywhere are learning how to make wise use of natural resources to ultimately ben- efit and sustain future generations but clear goals, objectives and analogies are needed to reinforce the message. Conservation education initiatives can be compared to production of a food crop. A crop plant must first be selected to suit the growing environment then the fields prepared for planting. After planting, the growing plants must be cared for. Only after a successful harvest can the profit be realized.

Seed characteristics and asymbiotic germination of Galeandra batemanii Rolfe and G. greenwoodiana Warford

The genus Galeandra Lindl. is a member of subtribe Cyrtopodiinae (Dressler 1993). It is represented in the Americas, from Florida through Mexico and Central America and as far south as Argentina. In Mexico, suitable habitat of Galeandra batemanii Rolfe and of Galeandra greenwoodiana Warford is sparse, patchy and widely separated with sites 300 km or more apart (Warford 1994). Galeandra batemanii has been report- ed to be occasionally lithophytic (Pollard 1974). The genus Galeandra Lindl. is a member of subtribe Cyrtopodiinae (Dressler 1993). It is represented in the Americas, from Florida through Mexico and Central America and as far south as Argentina. In Mexico, suitable habitat of Galeandra batemanii Rolfe and of Galeandra greenwoodiana Warford is sparse, patchy and widely separated with sites 300 km or more apart (Warford 1994). Galeandra batemanii has been report- ed to be occasionally lithophytic (Pollard 1974).

Effects of trampling on a terrestrial orchid environment

Orchids and soil communities that support them may be affected when we monitor or conduct inves- tigative procedures, or through tourism especially during the blooming season, but this has never been investigated or quantified (Light 2004). The immedi- ate and direct effect of human disturbance including crushing of flowering plants and seedlings is obvious: broken stems are unlikely to resume growth and a season’s reproductive effort can be lost. Orchids and soil communities that support them may be affected when we monitor or conduct inves- tigative procedures, or through tourism especially during the blooming season, but this has never been investigated or quantified (Light 2004). The immedi- ate and direct effect of human disturbance including crushing of flowering plants and seedlings is obvious: broken stems are unlikely to resume growth and a season’s reproductive effort can be lost.

The role of common orchids in appreciating the complexity of biodiversity conservation

Para conservar especies se debe comprender su biología, ecología y su relativa vulnerabilidad a cambios. Para conservar la biodiversidad, necesitamos un entendimiento profundo del impacto de los disturbios naturales y antropogénicos, de las interacciones y, del rol que juega el ecosistema en la supervivencia de las especies. Las suposiciones de abundancia y declinación y por consiguiente el estatus de conservación puede ser totalmente erróneo si no se toman en cuenta aspectos críticos de la historia natural o las relaciones con otros organismos. Por más de dos décadas hemos monitoreado las poblaciones de dos orquídeas terrestres que crecen en la cercanía del Parque Gatineau, Québec, Canadá. La abundancia relativa y disponibilidad de poblaciones grandes de Cypripedium parviflorum var. pubescens y de la especie introducida Epipactis helleborine nos dio la oportunidad de realizar experimentos in situ y de desarrollar y evaluar aspectos de conservación los cuales no son ejecutables con orquídeas poco comunes o raras. Hemos aprendido que la distribución, congregación y persistencia de E. helleborine está relacionada con la de diversidad de árboles y también que las semillas de las orquídeas germinan mejor en tierra apisonada que en aquella que no presenta disturbio, sin embargo, la localidad sería una variable preponderante. Apisonamiento experimental ocasionado por el tráfico de transeúntes dentro de las localidades de colonias de orquídeas comunes ha revelado un impacto negativo en las comunidades de nemátodos fungívoros, lo que podría reflejar ligeros cambios en el ensamblaje fúngico del cual los nemátodos se alimentan. Entre tanto, las plantas maduras de C. parviflorum var. pubescens no parecen ser afectadas por los efectos que tienen los transeúntes en el sendero. Sin embargo, la germinación y la supervivencia de las plántulas podrían haber sido alteradas, pero no nos daremos cuenta de estos cambios en algún tiempo. To conserve a species, we must understand its biology, ecology, and relative vulnerability to change. To conserve biodiversity, we need a profound understanding of the relative impact of natural and anthropogenic disturbances and species interactions and of the role of the ecosystem in species survival. Assumptions of the basis for abundance and decline and therefore conservation status might be ill founded if we miss critical aspects of life history or of inter-relationships with other organisms. For more than two decades we have monitored populations of two common terrestrial orchids that grow in close proximity in Gatineau Park, Québec, Canada. The relative abundance and availability of large populations of Cypripedium parviflorum var. pubescens and of the introduced Epipactis helleborine presented us with an opportunity to conduct in situ experimentation, and to develop and evaluate conservation approaches not possible with uncommon or rare orchids. We have learned that the distribution, patchiness, and persistence of E. helleborine is related to the presence and diversity of trees and that seeds of this orchid in trampled soil may germinate better than those in undisturbed soil but that location is a likely overriding variable. Experimental trampling within colonies of common orchids has revealed that the fungivorous nematode community is negatively impacted by foot traffic, which could be reflecting subtle changes in the soil fungal assemblage upon which the nematodes feed. While mature plants of C. parviflorum var. pubescens do not seem to have been affected by nearby foot traffic, seed germination and seedling survival could have been altered, but we may not become aware of such changes for some time

Potential impact of insect herbivores on orchid conservation

When an orchid is deliberately or inadvertently relocated, it is likely to encounter a range of biological challenges to long term survival including a complex and dynamic insect community which could alter conservation expectations yet there have been few studies of the phytophagous insects associated with wild orchids. We have investigated the assemblage of such insects associated with terrestrial orchids being monitored in our long term studies in Gatineau Park, Québec, Canada. Aphids, leafminers, moths, thrips, weevils, and whiteflies were found to be injurious to orchids although in different combinations and with varying impact according to the orchid host, habitat and year. Loss of seeds and even complete desiccation of plants was observed. Where the leafminer, Parallelomma vittatum Meigen (Diptera: Scathophagidae) infested Cypripedium reginae Walter randomly, this was not the case with Cypripedium parviflorum var. pubescens (Willd.) Knight where specific plants were repeatedly infested. Some infestations such as with the leafminers seemed to be in equilibrium with parasitoids thus minimizing potential impact. A likely climate-related asynchrony of parasitoid and leafminer led to an outbreak in 2009 which heavily impacted the introduced Epipactis helleborine (L.) Crantz while a phenological shift in a thrips primary host, Trillium grandiflorum (Michaux) Salisb. (Melanthiaceae), in 2010, contributed to severe herbivory in habitats where both E. helleborine and trillium occurred. If climate change can lead to changes in insect abundance and impact on orchids, it would be useful to investigate the potential impact of phytophagous insects before assisted migration is considered as a conservation measure