Identifying drivers of forest resilience in long-term records from the Neotropics

Here, we use 30 long-term, high-resolution palaeoecological records from Mexico, Central and South America to address two hypotheses regarding possible drivers of resilience in tropical forests as measured in terms of recovery rates from previous disturbances. First, we hypothesize that faster recovery rates are associated with regions of higher biodiversity, as suggested by the insurance hypothesis. And second, that resilience is due to intrinsic abiotic factors that are location specific, thus regions presently displaying resilience in terms of persistence to current climatic disturbances should also show higher recovery rates in the past. To test these hypotheses, we applied a threshold approach to identify past disturbances to forests within each sequence. We then compared the recovery rates to these events with pollen richness before the event. We also compared recovery rates of each site with a measure of present resilience in the region as demonstrated by measuring global vegetation persistence to climatic perturbations using satellite imagery. Preliminary results indeed show a positive relationship between pre-disturbance taxonomic richness and faster recovery rates. However, there is less evidence to support the concept that resilience is intrinsic to a region; patterns of resilience apparent in ecosystems presently are not necessarily conservative through time.

Evidence for induction of humoral and cytotoxic immune responses against devil facial tumor disease cells in Tasmanian devils (Sarcophilus harrisii) immunized with killed cell preparations

Tasmanian devils (Sarcophilus harrisii) risk extinction from a contagious cancer, devil facial tumour disease (DFTD) in which the infectious agent is the tumor cell itself. Because devils are unable to produce an immune response against the tumor cells no devil has survived 'infection'. To promote an immune response we immunized healthy devils with killed DFTD tumor cells in the presence of adjuvants. Immune responses, including cytotoxicity and antibody production, were detected in five of the six devils. The incorporation of adjuvants that act via toll like receptors may provide additional signals to break 'immunological ignorance'. One of these devils was protected against a challenge with viable DFTD cells. This was a short-term protection as re-challenge one year later resulted in tumor growth. These results suggest that Tasmanian devils can generate immune responses against DFTD cells. With further optimization of immune stimulation it should be possible to protect Tasmanian devils against DFTD with an injectable vaccine.

Determining the response of African biota to climate change: using the past to model the future

Prediction of biotic responses to future climate change in tropical Africa tends to be based on two modelling approaches: bioclimatic species envelope models and dynamic vegetation models. Another complementary but underused approach is to examine biotic responses to similar climatic changes in the past as evidenced in fossil and historical records. This paper reviews these records and highlights the information that they provide in terms of understanding the local- and regional-scale responses of African vegetation to future climate change. A key point that emerges is that a move to warmer and wetter conditions in the past resulted in a large increase in biomass and a range distribution of woody plants up to 400–500 km north of its present location, the so-called greening of the Sahara. By contrast, a transition to warmer and drier conditions resulted in a reduction in woody vegetation in many regions and an increase in grass/savanna-dominated landscapes. The rapid rate of climate warming coming into the current interglacial resulted in a dramatic increase in community turnover, but there is little evidence for widespread extinctions. However, huge variation in biotic response in both space and time is apparent with, in some cases, totally different responses to the same climatic driver. This highlights the importance of local features such as soils, topography and also internal biotic factors in determining responses and resilience of the African biota to climate change, information that is difficult to obtain from modelling but is abundant in palaeoecological records.

Tumor-Specific Diagnostic Marker for Transmissible Facial Tumors of Tasmanian Devils

Devil facial tumor disease (DFTD) is a transmissible neoplasm that is threatening the survival of the Tasmanian devil. Genetic analyses have indicated that the disease is a peripheral nerve sheath neoplasm of Schwann cell origin. DFTD cells express genes characteristic of myelinating Schwann cells, and periaxin, a Schwann cell protein, has been proposed as a marker for the disease. Diagnosis of DFTD is currently based on histopathology, cytogenetics, and clinical appearance of the disease in affected animals. As devils are susceptible to a variety of neoplastic processes, a specific diagnostic test is required to differentiate DFTD from cancers of similar morphological appearance. This study presents a thorough examination of the expression of a set of Schwann cell and other neural crest markers in DFTD tumors and normal devil tissues. Samples from 20 primary DFTD tumors and 10 DFTD metastases were evaluated by immunohistochemistry for the expression of periaxin, S100 protein, peripheral myelin protein 22, nerve growth factor receptor, nestin, neuron specific enolase, chromogranin A, and myelin basic protein. Of these, periaxin was confirmed as the most sensitive and specific marker, labeling the majority of DFTD cells in 100% of primary DFTD tumors and DFTD metastases. In normal tissues, periaxin showed specificity for Schwann cells in peripheral nerve bundles. This marker was then evaluated in cultured devil Schwann cells, DFTD cell lines, and xenografted DFTD tumors. Periaxin expression was maintained in all these models, validating its utility as a diagnostic marker for the disease.

A Murine Xenograft Model for a Transmissible Cancer in Tasmanian Devils

The number of Tasmanian devils in the wild is rapidly declining owing to a transmissible cancer, devil facial tumor disease (DFTD). Although progress has been made to understand the spread of this disease, crucial research on the pathogenesis of DFTD has been limited because of the threatened status of the host species. Here, the authors describe the development of a NOD/SCID (nonobese diabetic / severe combined immunodeficiency) mouse model that reproduces DFTD and provides a much-needed model to undertake studies into this intriguing transmissible cancer. Histologically, the DFTD produced in NOD/SCID mice (xenografted DFTD) was indistinguishable from the DFTD identified in Tasmanian devils. At the protein level, all xenografted DFTD tumors expressed periaxin, a marker that confirmed the diagnosis of DFTD. The karyotype of DFTD in NOD/SCID mice reproduced similar chromosomal alterations as seen in diseased devils. Furthermore, each NOD/SCID mouse inoculated with cultured DFTD tumor cells developed tumors, whereas DFTD did not develop in any of the inoculated immune-competent BALB/c mice.

Results of the pilot study of DIADEM: a comprehensive disease management programme for type 2 diabetes

AIMS

The purpose of the study was to evaluate the feasibility and preliminary clinical effects of the DIADEM disease management programme for type 2 diabetic patients.

METHODS

The study was performed at two test sites (Cardiff, UK: Aachen, Germany) including 137 and 166 patients, respectively. In 16 study centres any patients with type 2 diabetes capable of communicating by phone and able to perform blood pressure, blood glucose or urine glucose self-measurements were included. The maximum programme duration was 6 months at Cardiff and 4 months at Aachen, during which patients were assessed for glycaemic control, cardiovascular risk profile and the presence of complications of diabetes. Data were entered via the internet to a central server.

RESULTS

At entry into the programme the patient group in Cardiff had significantly lower mean age (60.3+/-9.4 years versus 64.9+/-8.7 years, p<0.001) and duration of diabetes (6.1+/-5.7 years versus 7.4+/-7.0 years, p<0.05) than in Aachen, however body mass index (31.6+/-5.2 kg/m(2) versus 29.5+/-4.9 kg/m(2), p<0.01), HbA1c (7.7+/-1.2% versus 7.1+/-1.2%, p<0.001) and systolic blood pressure (138.4+/-15.1 mmHg versus 133.5+/-11.5 mmHg, p<0.001) were significantly higher. In contrast, total cholesterol (4.7+/-1.0 mmol/l versus 5.5+/-1.1 mmol/l, p<0.001) was significantly lower in Cardiff compared to Aachen. Following entry into the programme highly significant improvements in HbA1c (Cardiff from 7.7% to 7.1%, p<0.001; Aachen from 7.2% to 6.8%, p<0.05) and total cholesterol concentrations (Cardiff: 4.66-4.46 mmol/l; Aachen: 5.33-5.15 mmol/l; both p<0.05) were observed. There were no significant changes in blood pressure at either site.

CONCLUSIONS

Intensive diabetes care was delivered to DIADEM patients and relevant and significant improvements in diabetes care were achieved demonstrating that an IT-based diabetes disease management service can improve care for patients with type 2 diabetes.