The Interplay Between Life History and Environmental Stochasticity: Implications for the Management of Exploited Lizard Populations

SYNOPSIS. The sustainable use of wild species by local peopleis emerging as an important conservation strategy. The premiseis the economic value of species will justify their own preservationas well as the habitats they occupy. However, the lack of naturalhistory and demographic information for the majority of speciesbeing exploited or with potential uses presents challengingproblems for implementing sustainable use programs. Each yearin Argentina and Paraguay, an average of 1.9 million tegu lizardsof the genus Tupinambis are exploited for their skins. In spiteof the importance of tegus as a resource, their biology is poorlyknown and their populations have never been managed. The lifehistory of Tupinambis, like that of other exploited lizards,is characterized by a relatively long life span, a large clutchsize, several years of growth before reproduction, and highmortality of hatchlings. Importantly, the mortality of young-of-the-yearand the proportion of females reproducing each year are bothprobably strongly influenced by interannual environmental variation.Whenthese parameters were randomized in life table projections tosimulate the effects of environmental stochasticity, the populationgrowth rate was highly sensitive to environmental fluctuations.Monte Carlo simulations of different harvest strategies showedthat estimates of population growth rates were overwhelminglyinfluenced by environmental variation and the number of yearsincluded in the growth rate estimate, even in the face of seeminglylarge changes in adult mortality that would result from populationmanagement. These results are both encouraging and cautionaryfor Tupinambis conservation. On the one hand these patternscan help explain how Tupinambis populations may have persistedin spite of high and variable harvest levels during many years,but conversely, stochastic effects make it difficult to evaluatethe effects of conservation measures. Size and sex can be determinedfrom harvested skins, and pilot studies suggest that analysesof the annual harvest can provide valuable information for evaluatinglong-term population trends.     

The Results of Parenteral Injections of Sporulated or Unsporulated Oocysts of Eimeria bovis in Calves

SYNOPSIS. Five experiments using newborn Holstein-Friesian and weaner Hereford calves were conducted to observe the effects caused by parenteral injections of oocysts of Eimeria bovis . Sporulated oocysts were given intraperitoneally (IP), subcutaneously (SC), intramuscularly (IM) and intravenously (IV). Unsporulated oocysts or merozoites were given IP or IM.
Coccidiosis developed in calves in three experiments after they were inoculated IP with sporulated oocysts. Immunity to reinfection resulted from these infections. No infections occurred at any time after SC, IM or IV inoculation with sporulated oocysts or after IP or IM inoculation with unsporulated oocysts or merozoites.
Coccidiosis failed to occur in two experiments when special precautions were used to prevent puncture of the intestines during IP inoculations. There was no detectable immunological response to any of the inoculations unless intestinal infections occurred.
In one experiment sporulated oocysts were exposed to 60,000 r irradiation by x-ray in an attempt to attenuate the oocysts. Calves became infected when given orally administered oocysts irradiated at this level.     

Mesenchymal stromal cell therapy: progress in manufacturing and assessments of potency

Mesenchymal stromal cell (MSC) therapies have been pursued for a broad spectrum of indications but mixed reports on clinical efficacy have given rise to some degree of skepticism regarding the effectiveness of this approach. However, recent reports of successful clinical outcomes and regulatory approvals for graft-versus-host disease, Crohn's disease and critical limb ischemia have prompted a shift in this perspective. With hundreds of clinical trials involving MSCs currently underway and an increasing demand for large-scale manufacturing protocols, there is a critical need to develop standards that can be applied to processing methods and to establish consensus assays for both MSC processing control and MSC product release. Reference materials and validated, uniformly applied tests for quality control of MSC products are needed. Here, we review recent developments in MSC manufacturing technologies, release testing and potency assays. We conclude that, although MSCs hold considerable promise clinically, economies of scale have yet to be achieved although numerous bioreactor technologies for scalable production of MSCs exist. Additionally, rigorous disease-specific product testing and comprehensive understanding of mechanisms of action, which are linked to relevant process and product release potency assays, will be required to ensure that these therapies continue to be successful.     

Differential expression of interferon responsive genes in rodent models of transmissible spongiform encephalopathy disease

Background

Alzheimer's disease (AD) is characterized by a decline in cognitive function and accumulation of amyloid-β peptide (Aβ) in extracellular plaques. Mutations in amyloid precursor protein (APP) and presenilins alter APP metabolism resulting in accumulation of Aβ42, a peptide essential for the formation of amyloid deposits and proposed to initiate the cascade leading to AD. However, the role of Aβ40, the more prevalent Aβ peptide secreted by cells and a major component of cerebral Aβ deposits, is less clear. In this study, virally-mediated gene transfer was used to selectively increase hippocampal levels of human Aβ42 and Aβ40 in adult Wistar rats, allowing examination of the contribution of each to the cognitive deficits and pathology seen in AD.

Results

Adeno-associated viral (AAV) vectors encoding BRI-Aβ cDNAs were generated resulting in high-level hippocampal expression and secretion of the specific encoded Aβ peptide. As a comparison the effect of AAV-mediated overexpression of APPsw was also examined. Animals were tested for development of learning and memory deficits (open field, Morris water maze, passive avoidance, novel object recognition) three months after infusion of AAV. A range of impairments was found, with the most pronounced deficits observed in animals co-injected with both AAV-BRI-Aβ40 and AAV-BRI-Aβ42. Brain tissue was analyzed by ELISA and immunohistochemistry to quantify levels of detergent soluble and insoluble Aβ peptides. BRI-Aβ42 and the combination of BRI-Aβ40+42 overexpression resulted in elevated levels of detergent-insoluble Aβ. No significant increase in detergent-insoluble Aβ was seen in the rats expressing APPsw or BRI-Aβ40. No pathological features were noted in any rats, except the AAV-BRI-Aβ42 rats which showed focal, amorphous, Thioflavin-negative Aβ42 deposits.

Conclusion

The results show that AAV-mediated gene transfer is a valuable tool to model aspects of AD pathology in vivo, and demonstrate that whilst expression of Aβ42 alone is sufficient to initiate Aβ deposition, both Aβ40 and Aβ42 may contribute to cognitive deficits.     

Efficacy of hyaluronic acid binding assay in selecting motile spermatozoa with normal morphology at high magnification

Background  

The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x).     

A proposed framework for determining the environmental impact of replacing agricultural grassland with Miscanthus in Ireland

Energy crops offer an opportunity to substantially increase bioenergy resources which can replace rapidly depleting fossil fuel reserves and mitigate the effect of climate change. Energy crops are typically established within traditional agricultural systems such as tillage land or grassland. Associated land use conversion has environmental implications. The aim of this paper is to propose a framework to examine how such environmental implications can be assessed, based on (a) a Strategic Environmental Assessment (SEA) approach which considers potential impacts at different stages of a plan across a wide range of environmental receptors and (b) a literature review. The example we used was that of Miscanthus replacing grassland farming. This scenario is particularly relevant to Ireland, where over 90% of the agricultural land is permanent pasture, but is also applicable to grassland conversion throughout Europe and the United States. Two consecutive phases of land‐use change were identified for assessment, each with a distinct set of environmental impacts. The first was a transition phase, lasting from initial livestock clearance and grassland ploughing until the Miscanthus crop became established (2–3 years). The second phase was the mature crop phase, lasting up to 25 years. Miscanthus cultivation was more likely to impact negatively on the environment during the transition phase than the mature phase, primarily due to abrupt disturbance and the time required for a new equilibrium to establish. However, a literature review of the impact on the environmental receptors revealed that replacing Irish agricultural grassland with Miscanthus had the potential to improve biodiversity, water, air and soil quality, and climatic factors once the crop became established and reached maturity. In order to confirm these findings an appropriate monitoring programme involving objectives and indicators associated with each environmental receptor would need to be developed.