Reconstructing colonization dynamics to establish how human activities transformed island biodiversity

Drivers and dynamics of initial human migrations across individual islands and archipelagos are poorly understood, hampering assessments of subsequent modification of island biodiversity. We developed and tested a new statistical-simulation approach for reconstructing the pattern and pace of human migration across islands at high spatiotemporal resolutions. Using Polynesian colonisation of New Zealand as an example, we show that process-explicit models, informed by archaeological records and spatiotemporal reconstructions of past climates and environments, can provide new and important insights into the patterns and mechanisms of arrival and establishment of people on islands. We find that colonisation of New Zealand required there to have been a single founding population of approximately 500 people, arriving between 1233 and 1257 AD, settling multiple areas, and expanding rapidly over both North and South Islands. These verified spatiotemporal reconstructions of colonisation dynamics provide new opportunities to explore more extensively the potential ecological impacts of human colonisation on New Zealand's native biota and ecosystems.

Longitudinal Impacts of Precision Greenness on Alzheimer's Disease

BACKGROUND

The potential for greenness as a novel protective factor for Alzheimer's disease (AD) requires further exploration.

OBJECTIVES

This study assesses prospectively and longitudinally the association between precision greenness - greenness measured at the micro-environmental level, defined as the Census block - and AD incidence.

DESIGN

Older adults living in consistently high greenness Census blocks across 2011 and 2016 were compared to those living in consistently low greenness blocks on AD incidence during 2012-2016.

SETTING

Miami-Dade County, Florida, USA.

PARTICIPANTS

230,738 U.S. Medicare beneficiaries.

MEASUREMENTS

U.S. Centers for Medicare and Medicaid Services Chronic Condition Algorithm for AD based on ICD-9 codes, Normalized Difference Vegetation Index, age, sex, race/ethnicity, neighborhood income, and walkability.

RESULTS

Older adults living in the consistently high greenness tertile, compared to those in the consistently low greenness tertile, had 16% lower odds of AD incidence (OR=0.84, 95% CI: 0.76-0.94, p=0.0014), adjusting for age, sex, race/ethnicity, and neighborhood income. Age, neighborhood income and walkability moderated greenness' relationship to odds of AD incidence, such that younger ages (65-74), lower-income, and non-car dependent neighborhoods may benefit most from high greenness.

CONCLUSIONS

High greenness, compared to low greenness, is associated with lower 5-year AD incidence. Residents who are younger and/or who reside in lower-income, walkable neighborhoods may benefit the most from high greenness. These findings suggest that consistently high greenness at the Census block-level, may be associated with reduced odds of AD incidence at a population level.

Millennial processes of population decline, range contraction and near extinction of the European bison

European bison (Bison bonasus) were widespread throughout Europe during the late Pleistocene. However, the contributions of environmental change and humans to their near extinction have never been resolved. Using process-explicit models, fossils and ancient DNA, we disentangle the combinations of threatening processes that drove population declines and regional extinctions of European bison through space and across time. We show that the population size of European bison declined abruptly at the termination of the Pleistocene in response to rapid environmental change, hunting by humans and their interaction. Human activities prevented populations of European bison from rebounding in the Holocene, despite improved environmental conditions. Hunting caused range loss in the north and east of its distribution, while land use change was responsible for losses in the west and south. Advances in hunting technologies from 1500 CE were needed to simulate low abundances observed in 1870 CE. While our findings show that humans were an important driver of the extinction of the European bison in the wild, vast areas of its range vanished during the Pleistocene-Holocene transition because of post-glacial environmental change. These areas of its former range have been climatically unsuitable for millennia and should not be considered in reintroduction efforts.

Correlation between carotid intima-media thickness and patient outcomes in coronary artery disease in central South Africa

OBJECTIVES

Carotid intima-medial thickness (CIMT) is a non-invasive tool used to detect atherosclerosis and diagnose cardiovascular disease. This study aimed to determine whether pre-operative CIMT measurements correlated with intra- and postoperative outcomes in patients with acute coronary syndrome (ACS) undergoing coronary artery bypass graft (CABG) surgery.

METHODS

This retrospective, analytical cohort included 89 patients diagnosed with ACS who received CABG surgery. Patients were divided into two cohorts: group 1: normal CIMT < 0.07 cm and group 2: abnormal CIMT ≥ 0.07 cm. B-mode ultrasound was used to measure the CIMT in all patients. Pre-, intra- and postoperative data and complications were recorded for each patient.

RESULTS

The study included 77 (86.5%) males and 12 (13.5%) females. Pre-operative mean body mass index was significantly higher (p = 0.03) in group 2 than in group 1. Group 2 had a significantly increased incidence of diabetes (p = 0.008) and hypertension (p = 0.009), and increased NT-proBNP levels (p = 0.02). Intra- and postoperative outcomes between the groups were comparable, with no significant differences.

CONCLUSION

The study showed no correlation between abnormal CIMT and increased adverse intra- and postoperative patient outcomes. Therefore, the results of this study show CIMT should not be considered a tool to predict adverse events in patients undergoing CABG surgery.

Impact of Holocene environmental change on the evolutionary ecology of an Arctic top predator

The Arctic is among the most climatically sensitive environments on Earth, and the disappearance of multiyear sea ice in the Arctic Ocean is predicted within decades. As apex predators, polar bears are sentinel species for addressing the impact of environmental variability on Arctic marine ecosystems. By integrating genomics, isotopic analysis, morphometrics, and ecological modeling, we investigate how Holocene environmental changes affected polar bears around Greenland. We uncover reductions in effective population size coinciding with increases in annual mean sea surface temperature, reduction in sea ice cover, declines in suitable habitat, and shifts in suitable habitat northward. Furthermore, we show that west and east Greenlandic polar bears are morphologically, and ecologically distinct, putatively driven by regional biotic and genetic differences. Together, we provide insights into the vulnerability of polar bears to environmental change and how the Arctic marine ecosystem plays a vital role in shaping the evolutionary and ecological trajectories of its inhabitants.

Outcomes of single-ventricle physiology in central South Africa

INTRODUCTION

Single-ventricle physiology is a critical cardiac condition requiring early diagnosis and intervention. The objectives of this study were to report on the management and outcomes of patients diagnosed with single-ventricle physiology in central South Africa.

METHODS

This study was a retrospective, observational analysis of patients presenting with single-ventricle physiology at the Universitas Academic Hospital in central South Africa between November 1997 and June 2021.

RESULTS

Patients were referred from the Free State (54%) and Northern Cape (29%) provinces and Lesotho. One hundred and fifty-four patients presented with single-ventricle physiology: 114 received interventions and 40 were not eligible for intervention. Patients presented for the first time at a median age of 34.5 days, with patients from nearby districts presenting within a few days of birth. However, patients from outlying areas presented much later. Eighty-seven patients received systemic-to-pulmonary artery shunting or pulmonary artery banding. Sixty-three patients proceeded to bidirectional Glenn procedures, and 30 patients (26%) had full palliation to Fontan. Twenty-one patients died after stage 1, six after the Glenn procedure and two after the Fontan procedure. Overall, 34 (29.8%) patients were lost to follow up.

CONCLUSION

Patients in our study presented late and follow up of these patients was a challenge. The highest mortality rate occurs during the first stage of palliation. Outcomes from this study are comparable to other sub-Saharan studies.

Spatiotemporal influences of climate and humans on muskox range dynamics over multiple millennia

Processes leading to range contractions and population declines of Arctic megafauna during the late Pleistocene and early Holocene are uncertain, with intense debate on the roles of human hunting, climatic change, and their synergy. Obstacles to a resolution have included an overreliance on correlative rather than process-explicit approaches for inferring drivers of distributional and demographic change. Here, we disentangle the ecological mechanisms and threats that were integral in the decline and extinction of the muskox (Ovibos moschatus) in Eurasia and in its expansion in North America using process-explicit macroecological models. The approach integrates modern and fossil occurrence records, ancient DNA, spatiotemporal reconstructions of past climatic change, species-specific population ecology, and the growth and spread of anatomically modern humans. We show that accurately reconstructing inferences of past demographic changes for muskox over the last 21,000 years require high dispersal abilities, large maximum densities, and a small Allee effect. Analyses of validated process-explicit projections indicate that climatic change was the primary driver of muskox distribution shifts and demographic changes across its previously extensive (circumpolar) range, with populations responding negatively to rapid warming events. Regional analyses show that the range collapse and extinction of the muskox in Europe (~13,000 years ago) was likely caused by humans operating in synergy with climatic warming. In Canada and Greenland, climatic change and human activities probably combined to drive recent population sizes. The impact of past climatic change on the range and extinction dynamics of muskox during the Pleistocene-Holocene transition signals a vulnerability of this species to future increased warming. By better establishing the ecological processes that shaped the distribution of the muskox through space and time, we show that process-explicit macroecological models have important applications for the future conservation and management of this iconic species in a warming Arctic.

Faster ocean warming threatens richest areas of marine biodiversity

The vulnerability of marine biodiversity to accelerated rates of climatic change is poorly understood. By developing a new method for identifying extreme oceanic warming events during Earth's most recent deglaciation, and comparing these to 21st century projections, we show that future rates of ocean warming will disproportionately affect the most speciose marine communities, potentially threatening biodiversity in more than 70% of current-day global hotspots of marine species richness. The persistence of these richest areas of marine biodiversity will require many species to move well beyond the biogeographic realm where they are endemic, at rates of redistribution not previously seen. Our approach for quantifying exposure of biodiversity to past and future rates of oceanic warming provides new context and scalable information for deriving and strengthening conservation actions to safeguard marine biodiversity under climate change.

Process-explicit models reveal pathway to extinction for woolly mammoth using pattern-oriented validation

Pathways to extinction start long before the death of the last individual. However, causes of early stage population declines and the susceptibility of small residual populations to extirpation are typically studied in isolation. Using validated process-explicit models, we disentangle the ecological mechanisms and threats that were integral in the initial decline and later extinction of the woolly mammoth. We show that reconciling ancient DNA data on woolly mammoth population decline with fossil evidence of location and timing of extinction requires process-explicit models with specific demographic and niche constraints, and a constrained synergy of climatic change and human impacts. Validated models needed humans to hasten climate-driven population declines by many millennia, and to allow woolly mammoths to persist in mainland Arctic refugia until the mid-Holocene. Our results show that the role of humans in the extinction dynamics of woolly mammoth began well before the Holocene, exerting lasting effects on the spatial pattern and timing of its range-wide extinction.

Longitudinal impacts of greenness on cardiovascular disease conditions

Introduction

Environmental determinants of health, such as greenness, play an increasing role in our understanding of cardiovascular disease, and can inform how to address geographic cardiovascular disparities. This study assesses the impact of greenness and changes in greenness on cardiovascular disease.

Purpose

The purpose of this study is to investigate the impact of greenness and changes in greenness on cardiovascular disease diagnoses.

Methods

The sample for this prospective, longitudinal study was comprised of 243,558 U.S. Medicare beneficiaries 65 years or older, residing on the same Census Block from 2011 through 2016, and who had a Miami-Dade residential 9-digit zip code. Analyses examined the impact of greenness, measured by mean block-level Normalized Difference Vegetation index (NDVI) from satellite imagery to incidence of new cardiovascular conditions including: acute myocardial infarction, atrial fibrillation, heart failure, ischemic heart disease, hypertension, and stroke/ transient ischemic attack. Zero-inflated poisson regression was used to model the odds of developing any new cardiovascular disease and number of new cardiovascular conditions based on block level greenness while adjusting for individual age, gender, race/ethnicity, number of baseline cardiovascular conditions, and neighborhood characteristics including income and walkability.

Results

Living in a higher greenness Census Block was associated with lower odds of having at least one new cardiovascular condition and having a small number of new conditions, adjusting for individual and neighborhood level characteristics. When compared to individuals living in the lowest tertile of greenness throughout the study, those individuals living in the highest tertile of greenness throughout the study had a 16% lower odds of having any new cardiovascular conditions (OR=0.84, 95% CI: 0.79–0.90, p&lt;0.001) and among individuals developing at least one new cardiovascular disease, 4% fewer new cardiovascular conditions (OR=0.96, 95% CI: 0.92–0.99, p&lt;0.05). When compared to individuals living in the lowest tertile of greenness throughout the study, those individuals living in areas that increased their greenness from the lowest tertile to the highest tertile of greenness had a 15% lower odds of having any new cardiovascular conditions (OR=0.85, 95% CI: 0.75–0.97, p&lt;0.001) and among individuals developing at least one new cardiovascular disease, 9% fewer new cardiovascular conditions (OR=0.91, 95% CI: 0.83–0.99, p&lt;0.05).

Conclusions

High greenness is associated with lower rates of cardiovascular conditions over time, both when greenness increases and when a Census Block maintains high greenness. It is remarkable that these effects appear in five years, a relatively short amount of time for a positive environmental impact; and that even for those who began in the lowest greenness tertile, an increase to the high greenness tertile had a significant effect.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Robert Wood Johnson Evidence for Action Grant

Identifying island safe havens to prevent the extinction of the World's largest lizard from global warming

The Komodo dragon (Varanus komodoensis) is an endangered, island‐endemic species with a naturally restricted distribution. Despite this, no previous studies have attempted to predict the effects of climate change on this iconic species. We used extensive Komodo dragon monitoring data, climate, and sea‐level change projections to build spatially explicit demographic models for the Komodo dragon. These models project the species’ future range and abundance under multiple climate change scenarios. We ran over one million model simulations with varying model parameters, enabling us to incorporate uncertainty introduced from three main sources: (a) structure of global climate models, (b) choice of greenhouse gas emission trajectories, and (c) estimates of Komodo dragon demographic parameters. Our models predict a reduction in range‐wide Komodo dragon habitat of 8%–87% by 2050, leading to a decrease in habitat patch occupancy of 25%–97% and declines of 27%–99% in abundance across the species' range. We show that the risk of extirpation on the two largest protected islands in Komodo National Park (Rinca and Komodo) was lower than other island populations, providing important safe havens for Komodo dragons under global warming. Given the severity and rate of the predicted changes to Komodo dragon habitat patch occupancy (a proxy for area of occupancy) and abundance, urgent conservation actions are required to avoid risk of extinction. These should, as a priority, be focused on managing habitat on the islands of Komodo and Rinca, reflecting these islands’ status as important refuges for the species in a warming world. Variability in our model projections highlights the importance of accounting for uncertainties in demographic and environmental parameters, structural assumptions of global climate models, and greenhouse gas emission scenarios when simulating species metapopulation dynamics under climate change.

StableClim, continuous projections of climate stability from 21000 BP to 2100 CE at multiple spatial scales

Paleoclimatic data are used in eco-evolutionary models to improve knowledge of biogeographical processes that drive patterns of biodiversity through time, opening windows into past climate–biodiversity dynamics. Applying these models to harmonised simulations of past and future climatic change can strengthen forecasts of biodiversity change. StableClim provides continuous estimates of climate stability from 21,000 years ago to 2100 C.E. for ocean and terrestrial realms at spatial scales that include biogeographic regions and climate zones. Climate stability is quantified using annual trends and variabilities in air temperature and precipitation, and associated signal-to-noise ratios. Thresholds of natural variability in trends in regional- and global-mean temperature allow periods in Earth’s history when climatic conditions were warming and cooling rapidly (or slowly) to be identified and climate stability to be estimated locally (grid-cell) during these periods of accelerated change. Model simulations are validated against independent paleoclimate and observational data. Projections of climatic stability, accessed through StableClim, will improve understanding of the roles of climate in shaping past, present-day and future patterns of biodiversity.

Measurement(s)	climate change • climate • temperature of air • volume of hydrological precipitation
Technology Type(s)	computational modeling technique • digital curation
Factor Type(s)	timing of temperature and precipitation estimates
Sample Characteristic - Environment	climate system
Sample Characteristic - Location	Earth (planet)

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12831935

Using paleo-archives to safeguard biodiversity under climate change

Strategies for 21st-century environmental management and conservation under global change require a strong understanding of the biological mechanisms that mediate responses to climate- and human-driven change to successfully mitigate range contractions, extinctions, and the degradation of ecosystem services. Biodiversity responses to past rapid warming events can be followed in situ and over extended periods, using cross-disciplinary approaches that provide cost-effective and scalable information for species' conservation and the maintenance of resilient ecosystems in many bioregions. Beyond the intrinsic knowledge gain such integrative research will increasingly provide the context, tools, and relevant case studies to assist in mitigating climate-driven biodiversity losses in the 21st century and beyond.

Models of spatiotemporal variation in rabbit abundance reveal management hot spots for an invasive species

The European rabbit (Oryctolagus cuniculus) is a notorious economic and environmental pest species in its invasive range. To better understand the population and range dynamics of this species, 41 yr of abundance data have been collected from 116 unique sites across a broad range of climatic and environmental conditions in Australia. We analyzed this time series of abundance data to determine whether interannual variation in climatic conditions can be used to map historic, contemporary, and potential future fluctuations in rabbit abundance from regional to continental scales. We constructed a hierarchical Bayesian regression model of relative abundance that corrected for observation error and seasonal biases. The corrected abundances were regressed against environmental and disease variables in order to project high spatiotemporal resolution, continent-wide rabbit abundances. We show that rabbit abundance in Australia is highly variable in space and time, being driven primarily by internnual variation in temperature and precipitation in concert with the prevalence of a non-pathogenic virus. Moreover, we show that internnual variation in local spatial abundances can be mapped effectively at a continental scale using highly resolved spatiotemporal predictors, allowing "hot spots" of persistently high rabbit abundance to be identified. Importantly, cross-validated model performance was fair to excellent within and across distinct climate zones. Long-term monitoring data for invasive species can be used to map fine-scale spatiotemporal fluctuations in abundance patterns when accurately accounting for inherent sampling biases. Our analysis provides ecologists and pest managers with a clearer understanding of the determinants of rabbit abundance in Australia, offering an important new approach for predicting spatial abundance patterns of invasive species at the near-term temporal scales that are directly relevant to resource management.

Spatial resilience of the Great Barrier Reef under cumulative disturbance impacts

In the face of increasing cumulative effects from human and natural disturbances, sustaining coral reefs will require a deeper understanding of the drivers of coral resilience in space and time. Here we develop a high-resolution, spatially explicit model of coral dynamics on Australia's Great Barrier Reef (GBR). Our model accounts for biological, ecological and environmental processes, as well as spatial variation in water quality and the cumulative effects of coral diseases, bleaching, outbreaks of crown-of-thorns starfish (Acanthaster cf. solaris), and tropical cyclones. Our projections reconstruct coral cover trajectories between 1996 and 2017 over a total reef area of 14,780 km² , predicting a mean annual coral loss of -0.67%/year mostly due to the impact of cyclones, followed by starfish outbreaks and coral bleaching. Coral growth rate was the highest for outer shelf coral communities characterized by digitate and tabulate Acropora spp. and exposed to low seasonal variations in salinity and sea surface temperature, and the lowest for inner-shelf communities exposed to reduced water quality. We show that coral resilience (defined as the net effect of resistance and recovery following disturbance) was negatively related to the frequency of river plume conditions, and to reef accessibility to a lesser extent. Surprisingly, reef resilience was substantially lower within no-take marine protected areas, however this difference was mostly driven by the effect of water quality. Our model provides a new validated, spatially explicit platform for identifying the reefs that face the greatest risk of biodiversity loss, and those that have the highest chances to persist under increasing disturbance regimes.

The Australian National Rabbit Database: 50 yr of population monitoring of an invasive species

With ongoing introductions into Australia since the 1700s, the European rabbit (Oryctolagus cuniculus) has become one of the most widely distributed and abundant vertebrate pests, adversely impacting Australia's biodiversity and agroeconomy. To understand the population and range dynamics of the species and its impacts better, occurrence and abundance data have been collected by researchers and citizens from sites covering a broad spectrum of climatic and environmental conditions in Australia. The lack of a common and accessible repository for these data has, however, limited their use in determining important spatiotemporal drivers of the structure and dynamics of the geographical range of rabbits in Australia. To meet this need, we created the Australian National Rabbit Database, which combines more than 50 yr of historical and contemporary survey data collected from throughout the range of the species in Australia. The survey data, obtained from a suite of complementary monitoring methods, were combined with high-resolution weather, climate, and environmental information, and an assessment of data quality. The database provides records of rabbit occurrence (689,265 records) and abundance (51,241 records, >120 distinct sites) suitable for identifying the spatiotemporal drivers of the rabbit's distribution and for determining spatial patterns of variation in its key life-history traits, including maximum rates of population growth. Because all data are georeferenced and date stamped, they can be coupled with information from other databases and spatial layers to explore the potential effects of rabbit occurrence and abundance on Australia's native wildlife and agricultural production. The Australian National Rabbit Database is an important tool for understanding and managing the European rabbit in its invasive range and its effects on native biodiversity and agricultural production. It also provides a valuable resource for addressing questions related to the biology, success, and impacts of invasive species more generally. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper.

Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas, Convolvulaceae) complex

Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa. Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy. 2C DNA content of hexaploid I. batatas ranged between 3.12-3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana, 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. ×leucantha, I. tiliacea, I. trifida and I. triloba, 2C DNA content was 1.01-1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea, were clearly different from the other diploid species, with 2C of 1.47-1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases. DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida, the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas.

Efficacy of lethal-trap devices to improve the welfare of trapped wild dogs

Context Wildlife and pest managers and stakeholders should constantly aim to improve animal-welfare outcomes when foot-hold trapping pest animals. To minimise stress and trauma to trapped animals, traps should be checked at least once every 24h, normally as soon after sunrise as possible. If distance, time, environmental or geographical constraints prevent this, toxins such as strychnine can be fitted to trap jaws to induce euthanasia. However, strychnine is considered to have undesirable animal-welfare outcomes because animals are conscious while clinical signs of intoxication are present. A toxin considered more humane, para-aminopropiophenone (PAPP), is available to induce euthanasia in trapped animals but is untested for presentation and efficacy. Aim We tested the efficacy of two types of lethal trap device (LTD’s), each using a paste formulation of PAPP as the active toxin to replace the use of strychnine on foot-hold jaw traps. Methods Elastomer LTDs and PAPP-cloths were fitted to jaw traps set to capture wild dogs (Canis familiaris). Camera-trap data was used to record animal behaviours after capture and to determine the efficacy of both modalities. Key results Every trapped wild dog (n=117) gnawed at the elastomer LTD’s or PAPP-cloth attached to the trap jaws that restrained them; one dog failed to liberate the toxin. From the dogs caught in the main trial (n=56), a mortality rate of 84% and 87% was reported respectively. The mean time from trap-to-death for elastomer LTDs was 64min and 68min for PAPP-cloths. Conclusions Elastomer LTDs and PAPP cloths combined caused the mortality of 85% of captured dogs. This efficacy could be improved by adopting the recommendations discussed in the present study for deploying PAPP-based LTDs during trap deployment. Implications PAPP-based LTDs offer an alternative option to the use of strychnine and improve the welfare outcomes for trapped predators, especially where traps are not checked within the recommended 24-h period.

How complex should models be? Comparing correlative and mechanistic range dynamics models

Criticism has been levelled at climate-change-induced forecasts of species range shifts that do not account explicitly for complex population dynamics. The relative importance of such dynamics under climate change is, however, undetermined because direct tests comparing the performance of demographic models vs. simpler ecological niche models are still lacking owing to difficulties in evaluating forecasts using real-world data. We provide the first comparison of the skill of coupled ecological-niche-population models and ecological niche models in predicting documented shifts in the ranges of 20 British breeding bird species across a 40-year period. Forecasts from models calibrated with data centred on 1970 were evaluated using data centred on 2010. We found that more complex coupled ecological-niche-population models (that account for dispersal and metapopulation dynamics) tend to have higher predictive accuracy in forecasting species range shifts than structurally simpler models that only account for variation in climate. However, these better forecasts are achieved only if ecological responses to climate change are simulated without static snapshots of historic land use, taken at a single point in time. In contrast, including both static land use and dynamic climate variables in simpler ecological niche models improve forecasts of observed range shifts. Despite being less skilful at predicting range changes at the grid-cell level, ecological niche models do as well, or better, than more complex models at predicting the magnitude of relative change in range size. Therefore, ecological niche models can provide a reasonable first approximation of the magnitude of species' potential range shifts, especially when more detailed data are lacking on dispersal dynamics, demographic processes underpinning population performance, and change in land cover.

Why decadal to century timescale palaeoclimate data are needed to explain present-day patterns of biological diversity and change

The current distribution of species, environmental conditions and their interactions represent only one snapshot of a planet that is continuously changing, in part due to human influences. To distinguish human impacts from natural factors, the magnitude and pace of climate shifts, since the Last Glacial Maximum, are often used to determine whether patterns of diversity today are artefacts of past climate change. In the absence of high-temporal resolution palaeoclimate reconstructions, this is generally done by assuming that past climate change occurred at a linear pace between widely spaced (usually, ≥1,000 years) climate snapshots. We show here that this is a flawed assumption because regional climates have changed significantly across decades and centuries during glacial-interglacial cycles, likely causing rapid regional replacement of biota. We demonstrate how recent atmosphere-ocean general circulation model (AOGCM) simulations of the climate of the past 21,000 years can provide credible estimates of the details of climate change on decadal to centennial timescales, showing that these details differ radically from what might be inferred from longer timescale information. High-temporal resolution information can provide more meaningful estimates of the magnitude and pace of climate shifts, the location and timing of drivers of physiological stress, and the extent of novel climates. They also produce new opportunities to directly investigate whether short-term climate variability is more important in shaping biodiversity patterns rather than gradual changes in long-term climatic means. Together, these more accurate measures of past climate instability are likely to bring about a better understanding of the role of palaeoclimatic change and variability in shaping current macroecological patterns in many regions of the world.

Evidence of early defects in Cajal-Retzius cell localization during brain development in a mouse model of dystroglycanopathy

AIMS

The secondary dystroglycanopathies represent a heterogeneous group of congenital muscular dystrophies characterized by the defective glycosylation of alpha dystroglycan. These disorders are associated with mutations in at least 17 genes, including Fukutin-related protein (FKRP). At the severe end of the clinical spectrum there is substantial brain involvement, and cobblestone lissencephaly is highly suggestive of these disorders. The precise pathogenesis of this phenotype has, however, remained unclear with most attention focused on the disruption to the radial glial scaffold. Here, we set out to investigate whether lesions are apparent prior to the differentiation of the radial glia.

METHODS

A detailed investigation of the structural brain defects from embryonic day 10.5 (E10.5) up until the time of birth (P0) was undertaken in the Fkrp-deficient mice (FKRP^KD ). Reelin, and downstream PI3K/Akt signalling pathways were analysed using Western blot.

RESULTS

We show that early basement membrane defects and neuroglial ectopia precede radial glial cell differentiation. Furthermore, we identify mislocalization of Cajal-Retzius cells which nonetheless is not associated with any apparent disruption to the reelin, and downstream PI3K/Akt signalling pathways.

CONCLUSIONS

These observations identify Cajal-Retzius cell mislocalization as an early event during the development of cortical defects thereby identifying an earlier onset and more complex pathogenesis than originally reported for the secondary dystroglycanopathies. Overall this study provides new insight into central nervous system involvement in this group of diseases.

First Melody(®) valve implantations in Africa

Congenital heart lesions involving the right ventricular outflow tract (RVOT) are a common problem in paediatric cardiology. These patients need multiple surgical interventions in the form of valved conduits over a lifetime. Surgical re-valvulation was the standard treatment option until the introduction of percutaneous pulmonary valves over a decade ago. These valves can be used to prolong the lifespan of conduits and reduce the number of re-operations. The Melody(®) valve (Medtronic, Minneapolis, MN, USA) was introduced as the first dedicated percutaneous pulmonary valve. Percutaneous pulmonary valves can be implanted successfully and have the advantage of short hospitalisations. We describe the first three Melody(®) valve implantations in Africa.

Hydrologic landscape regionalisation using deductive classification and random forests

Landscape classification and hydrological regionalisation studies are being increasingly used in ecohydrology to aid in the management and research of aquatic resources. We present a methodology for classifying hydrologic landscapes based on spatial environmental variables by employing non-parametric statistics and hybrid image classification. Our approach differed from previous classifications which have required the use of an a priori spatial unit (e.g. a catchment) which necessarily results in the loss of variability that is known to exist within those units. The use of a simple statistical approach to identify an appropriate number of classes eliminated the need for large amounts of post-hoc testing with different number of groups, or the selection and justification of an arbitrary number. Using statistical clustering, we identified 23 distinct groups within our training dataset. The use of a hybrid classification employing random forests extended this statistical clustering to an area of approximately 228,000 km² of south-eastern Australia without the need to rely on catchments, landscape units or stream sections. This extension resulted in a highly accurate regionalisation at both 30-m and 2.5-km resolution, and a less-accurate 10-km classification that would be more appropriate for use at a continental scale. A smaller case study, of an area covering 27,000 km², demonstrated that the method preserved the intra- and inter-catchment variability that is known to exist in local hydrology, based on previous research. Preliminary analysis linking the regionalisation to streamflow indices is promising suggesting that the method could be used to predict streamflow behaviour in ungauged catchments. Our work therefore simplifies current classification frameworks that are becoming more popular in ecohydrology, while better retaining small-scale variability in hydrology, thus enabling future attempts to explain and visualise broad-scale hydrologic trends at the scale of catchments and continents.

Predicting the likely response of data-poor ecosystems to climate change using space-for-time substitution across domains

Predicting ecological response to climate change is often limited by a lack of relevant local data from which directly applicable mechanistic models can be developed. This limits predictions to qualitative assessments or simplistic rules of thumb in data-poor regions, making management of the relevant systems difficult. We demonstrate a method for developing quantitative predictions of ecological response in data-poor ecosystems based on a space-for-time substitution, using distant, well-studied systems across an inherent climatic gradient to predict ecological response. Changes in biophysical data across the spatial gradient are used to generate quantitative hypotheses of temporal ecological responses that are then tested in a target region. Transferability of predictions among distant locations, the novel outcome of this method, is demonstrated via simple quantitative relationships that identify direct and indirect impacts of climate change on physical, chemical and ecological variables using commonly available data sources. Based on a limited subset of data, these relationships were demonstrably plausible in similar yet distant (>2000 km) ecosystems. Quantitative forecasts of ecological change based on climate-ecosystem relationships from distant regions provides a basis for research planning and informed management decisions, especially in the many ecosystems for which there are few data. This application of gradient studies across domains - to investigate ecological response to climate change - allows for the quantification of effects on potentially numerous, interacting and complex ecosystem components and how they may vary, especially over long time periods (e.g. decades). These quantitative and integrated long-term predictions will be of significant value to natural resource practitioners attempting to manage data-poor ecosystems to prevent or limit the loss of ecological value. The method is likely to be applicable to many ecosystem types, providing a robust scientific basis for estimating likely impacts of future climate change in ecosystems where no such method currently exists.

Flow cytometry analysis: a quantitative method for collagen VI deficiency screening

Mutations in COL6A1, COL6A2 and COL6A3 genes result in collagen VI myopathies: Ullrich congenital muscular dystrophy (UCMD), Bethlem myopathy (BM) and intermediate phenotypes. At present, none of the existing diagnostic techniques for evaluating collagen VI expression is quantitative, and the detection of subtle changes in collagen VI expression remains challenging. We investigated flow cytometry analysis as a means of quantitatively measuring collagen VI in primary fibroblasts and compared this method with the standard method of fibroblast collagen VI immunohistochemical analysis. Eight UCMD and five BM molecularly confirmed patients were studied and compared to five controls. Flow cytometry analysis consistently detected a reduction of collagen VI of at least 60% in all UCMD cases. In BM cases the levels of collagen VI were variable but on average 20% less than controls. Flow cytometry analysis provides an alternative method for screening for collagen VI deficiency at the protein level in a quantitative, time and cost-effective manner.

Cardiac abnormalities and facial anthropometric measurements in children from the Free State and Northern Cape provinces of South Africa with chromosome 22q11.2 microdeletion

INTRODUCTION

Microdeletions of chromosome 22 are common and have a prevalence of at least 1/4 000. Cardiac abnormalities, abnormal facial features and palatal abnormalities are frequently present in these patients.

AIM

To describe the cardiac lesions and selected measurable facial features in children from the Free State and Northern Cape presenting at the Cardiology Unit of the Universitas Academic Hospital complex in Bloemfontein.

METHODS

This was a prospective study in which patients with abnormal facial characteristics were tested using a fluorescence in situ hybridisation (FISH) probe for the 22q11.2 microdeletion. Forty children tested positive for the microdeletion. All patients underwent an echocardiogram and where possible, facial anthropometric measurements were performed.

RESULTS

The median age at diagnosis was 3.6 years (range 0.04 years, i.e. 2 weeks to 16.2 years). Tetralogy with or without pulmonary atresia was diagnosed in 43% (n = 17) of the children and truncus arteriosus in 20% (n = 8). A rightsided aortic arch was present in 43% (n = 17) of the patients. Mid-facial height was slightly longer (median = 1.0; range -0.5 to 3.3) and width narrower (median = -1.4; range -2.2 to 0.1) than normal. Ear height and width were notably small compared to normal, with median -scores = -3.3 (range -4.8 to -2.6) and = -2.4 (range -3.4 to -1.4), respectively.

CONCLUSIONS

Microdeletions of chromosome 22q11 are present in children from the Free State and Northern Cape. Conotruncal cyanotic heart lesions, especially tetralogy with or without pulmonary atresia and truncus arteriosus were the most frequent congenital cardiac diagnoses. A right-sided aortic arch was also commonly present in these children. Facial features varied and small ears were the most noteworthy anthropometric feature. A right-sided aortic arch with or without a congenital cardiac lesion, a long, narrow mid-face and small ears should alert the physician to the possibility of a microdeletion on the long arm of chromosome 22.

Class I antigens of the bovine major histocompatibility system are weakly associated with variation in faecal worm egg counts in naturally infected cattle

Three bulls selected for high faecal worm egg counts and three bulls selected for low faecal worm egg counts were mated to Africander-Hereford cross cows. Faecal worm egg counts were taken on four occasions from the 132 offspring. Also, each animal was typed for 32 class I antigens of the bovine major histocompatibility system (BoLA). Least squares analysis of variance showed that line, sex and some of the antigens were associated with differences in worm egg output in the faeces. After adjusting for the effects of line and sex, cattle with antigen W9 had about twice as many worm eggs in their faeces as cattle without W9; cattle with antigen CA45 had about half the concentration of faecal worm eggs as cattle without CA45. However, the antigen associations were of borderline significance at the 5% level and more work in additional populations is necessary to confirm these associations.

A comparison of bovine lymphocyte antigens

In Canberra, 31 antigens have been described on the surface of bovine lymphocytes. Seven antigens are subgroups of other antigens. Eleven antigens are similar to the eleven antigens which have been described in Melbourne. Fourteen antigens are similar to twelve international-workshop antigens and two European-workshop antigens.

Muscular dystrophies due to defective glycosylation of dystroglycan

Muscular dystrophies are a clinically and genetically heterogeneous group of disorders. Until recently most of the proteins associated with muscular dystrophies were believed to be proteins of the sarcolemma associated with reinforcing the plasma membrane or in facilitating its re-sealing following injury. In the last few years a novel and frequent pathogenic mechanism has been identified that involves the abnormal glycosylation of alpha-dystroglycan (ADG). This peripheral membrane protein undergoes complex and crucial glycosylation steps that enable it to interact with LG domain containing extracellular matrix proteins such as laminins, agrin and perlecan. Mutations in six genes (POMT1, POMT2, POMGnT1, fukutin, FKRP and LARGE) have been identified in patients with reduced glycosylation of ADG. While initially a clear correlation between gene defect and phenotype was observed for each of these 6 genes (for example, Walker Warburg syndrome was associated with mutations in POMT1 and POMT2, Fukuyama congenital muscular dystrophy associated with fukutin mutations, and Muscle Eye Brain disease associated with POMGnT1 mutations), we have recently demonstrated that allelic mutations in each of these 6 genes can result in a much wider spectrum of clinical conditions. Thus, the crucial aspect in determining the phenotypic severity is not which gene is primarily mutated, but how severely the mutation affects the glycosylation of ADG. Systematic mutation analysis of these 6 glycosyltransferases in patients with a dystroglycan glycosylation disorder identifies mutations in approximately 65% suggesting that more genes have yet to be identified.

Evolution of genome size across some cultivated Allium species

Allium L. (Alliaceae), a genus of major economic importance, exhibits a great diversity in various morphological characters and particularly in life form, with bulbs and rhizomes. Allium species show variation in several cytogenetic characters such as basic chromosome number, ploidy level, and genome size. The purpose of the present investigation was to study the evolution of nuclear DNA amount, GC content, and life form. A phylogenetic approach was used on a sample of 30 Allium species, including major vegetable crops and their wild allies, belonging to the 3 major subgenera Allium, Amerallium, and Rhizirideum and 14 sections. A phylogeny was constructed using internal transcribed spacer (ITS) sequences of 43 accessions representing 30 species, and the nuclear DNA amount and the GC content of 24 Allium species were investigated by flow cytometry. For the first time, the nuclear DNA content of Allium cyaneum and Allium vavilovii was measured, and the GC content of 16 species was measured. We addressed the following questions: (i) Is the variation in nuclear DNA amount and GC content linked to the evolutionary history of these edible Allium species and their wild relatives? (ii) How did life form (rhizome or bulb) evolve in edible Allium? Our results revealed significant interspecific variation in the nuclear DNA amount as well as in the GC content. No correlation was found between the GC content and the nuclear DNA amount. The reconstruction of nuclear DNA amount on the phylogeny showed a tendency towards a decrease in genome size within the genus. The reconstruction of life form history showed that rhizomes evolved in the subgenus Rhizirideum from an ancestral bulbous life form and were subsequently lost at least twice independently in this subgenus.

A comparative analysis of collagen VI production in muscle, skin and fibroblasts from 14 Ullrich congenital muscular dystrophy patients with dominant and recessive COL6A mutations

Ullrich congenital muscular dystrophy (UCMD) is caused by recessive and dominant mutations in COL6A genes. We have analysed collagen VI expression in 14 UCMD patients. Sequencing of COL6A genes had identified homozygous and heterozygous mutations in 12 cases. Analysis of collagen VI in fibroblast cultures derived from eight of these patients showed reduced extracellular deposition in all cases and intracellular collagen VI staining in seven cases. This was observed even in cases that showed normal collagen VI labelling in skin biopsies. Collagen VI immunolabelling was reduced in all the available muscle biopsies. When comparisons were possible no correlation was seen between the extent of the reduction in the muscle and fibroblast cultures, the mode of inheritance or the severity of the clinical phenotype. Mutations affecting glycine substitutions in the conserved triple helical domain were common and all resulted in reduced collagen VI. This study expands the spectrum of collagen VI defects and shows that analysis of skin fibroblasts may be a useful technique for the detection of collagen VI abnormalities. In contrast, immunohistochemical analysis of skin biopsies may not always reveal an underlying collagen VI defect.

Phase 1 trial of the antiangiogenic peptide ATN-161 (Ac-PHSCN-NH(2)), a beta integrin antagonist, in patients with solid tumours

To evaluate the toxicity, pharmacological and biological properties of ATN-161, a five –amino-acid peptide derived from the synergy region of fibronectin, adult patients with advanced solid tumours were enrolled in eight sequential dose cohorts (0.1–16 mg kg⁻¹), receiving ATN-161 administered as a 10-min infusion thrice weekly. Pharmacokinetic sampling of blood and urine over 7 h was performed on Day 1. Twenty-six patients received from 1 to 14 4-week cycles of treatment. The total number of cycles administered to all patients was 86, without dose-limiting toxicities. At dose levels above 0.5 mg kg⁻¹, mean total clearance and volume of distribution showed dose-independent pharmacokinetics (PKs). At 8.0 and 16.0 mg kg⁻¹, clearance of ATN-161 was reduced, suggesting saturable PKs. Dose escalation was halted at 16 mg kg⁻¹ when drug exposure (area under the curve) exceeded that associated with efficacy in animal models. There were no objective responses. Six patients received more than four cycles of treatment (>112 days). Three patients received 10 or more cycles (⩾280 days). ATN-161 was well tolerated at all dose levels. Approximately, 1/3 of the patients in the study manifested prolonged stable disease. These findings suggest that ATN-161 should be investigated further as an antiangiogenic and antimetastatic cancer agent alone or with chemotherapy.

Non-sarcolemmal muscular dystrophies

The muscular dystrophies are characterised by progressive muscle weakness and wasting. Pathologically the hallmarks are muscle fibre degeneration and fibrosis. Several recessive forms of muscular dystrophy are caused by defects in proteins localised to the sarcolemma. However, it is now apparent that others are due to defects in a wide range of proteins including those which are either nuclear-related (Emery-Dreifuss type muscular dystrophies, oculopharyngeal muscular dystrophy), enzymatic (limb-girdle muscular dystrophy 2A, myotonic dystrophy) or sarcomeric (limb-girdle muscular dystrophies 1A and 2G). Although the clinical and molecular basis of these disorders is heterogeneous all display myopathic morphological features. These include variation in fibre size, an increase in internal nuclei, and some myofibrillar distortion. Degeneration and fibrosis occur, but usually not to the same extent as in muscular dystrophies associated with sarcolemmal protein defects. This review outlines the genetic basis of these "non-sarcolemmal" forms of dystrophy and discusses current ideas on their pathogenesis.

Disease severity in dominant Emery Dreifuss is increased by mutations in both emerin and desmin proteins

Individuals with the same genetic disorder often show remarkable differences in clinical severity, a finding generally attributed to the genetic background. We identified two patients with genetically proven Emery-Dreifuss muscular dystrophy (EDMD) who followed an unusual course and had uncommon clinicopathological findings. We hypothesized digenic inheritance and looked for additional molecular explanations. Mutations in additional separate genes were identified in both patients. The first patient was a member of a family with molecularly proven X-linked EDMD. However, the clinical features were unusually severe for this condition in the propositus: he presented at 2.5 years with severe proximal weakness and markedly elevated serum creatine kinase. Muscle weakness rapidly progressed, leading to loss of independent ambulation by the age of 12. In addition, the patient developed cardiac conduction system disease requiring pacing at the age of 11 and severe dilated cardiomyopathy in the early teens. Despite pacing, he had several syncopal episodes attributed to ventricular dysrhythmias. As these resemble the cardiac features of patients with the autosomal dominant variant of EDMD, we examined the lamin A/C gene, identifying a de-novo mutation in the propositus. The second patient had a cardioskeletal myopathy, similar to his mother who had died more than 20 years previously. Because of the dominant family history, a laminopathy was suspected and a mutation in exon 11 of the LMNA gene was identified. This mutation, however, was not present in his mother, but instead, surprisingly, was identified in his virtually asymptomatic father. Unusual accumulations of desmin found in the cardiac muscle of the propositus prompted us to examine the desmin gene in this patient, and in so doing, we identified a desmin mutation, in addition to the LMNA mutation in the propositus. These cases suggest that separate mutations in related proteins that are believed to interact, or that represent different parts of a presumed functional pathway, may synergistically contribute to disease severity in autosomal dominant EDMD. Furthermore, digenic inheritance may well contribute to the clinical severity of many other neuromuscular disorders.

Mutated fukutin-related protein (FKRP) localises as wild type in differentiated muscle cells

The mechanism of disease in forms of congenital and limb girdle muscular dystrophy linked to mutations in the gene encoding for Fukutin-related protein (FKRP) has previously been associated with the mis-localisation of FKRP from the Golgi apparatus. In the present report, we have transfected V5-tagged Fukutin-related protein expression constructs into differentiated C2C12 myotubes and the tibialis anterior of normal mice. The transfection of either wild type (WT) or several mutant constructs (P448L, C318Y, L276I) into myotubes consistently showed clear co-localisation with GM130, a Golgi marker. In contrast, whilst WT and the L276I localised to the Golgi of Cos-7 cells, the P448L and C318Y was mis-localised in the majority of these undifferentiated cells. The injection of the same constructs into the tibialis anterior of mice resulted in similar localisation of both the WT and all the mutants. Immunolabelling of FKRP in the muscle of MDC1C and LGMD2I patients was found to be indistinguishable from normal controls. Overall, these data suggest that retention in the endoplasmic reticulum of FKRP is not the main mechanism of disease but that this may instead relate to a disruption of the functional activity of this putative enzyme with its substrate(s) in the Golgi.

Congenital muscular dystrophy: molecular and cellular aspects

The congenital muscular dystrophies are a clinically and genetically heterogeneous group of neuromuscular disorders. Each form has a characteristic phenotype, but there is overlap between some entities and their classification is based on a combination of clinical features and the primary or secondary protein defect. Recent studies have identified the genetic basis of a number of congenital muscular dystrophies (11 genes in total) and have recognised a novel pathological mechanism that highlights the importance of the correct posttranslational processing of proteins, in particular alpha-dystroglycan. Diagnosis of these conditions has been aided by the availability of specific antibodies for each protein and a better understanding of the protein changes that accompany each condition. In this review we present the major molecular, clinical and diagnostic aspects of each group of congenital muscular dystrophy with an emphasis in the more recent developments.

Cardiac findings in children admitted to a hospital general ward in South Africa: a comparison of HIV-infected and uninfected children

The aim of this prospective observational study was to determine the presence of cardiac abnormalities in HIV infected versus uninfected children who were admitted to a general paediatric ward during a two-month period. HIV status was determined by antibody and p24 antigen testing. Clinical information, echocardiography and electrocardiography (ECG) were performed for all children. There were 90 HIV-infected and 118 uninfected children. The median age was 9.6 and 11.8 months for infected and uninfected children, respectively. Baseline left ventricular dysfunction, defined as a shortening fraction < or = 25%, was found in 13 (17%) of the HIV-infected children compared to 5 (8%) uninfected children (p < 0.05). Left ventricular end-diastolic enlargement above the 98th percentile for age was found in 24% of the infected and 20% of uninfected children. Pericardial effusions, although common, were sub-clinical and not different in the groups. ECG findings and resting heart rates were also similar. Left ventricular dysfunction was the most significant cardiac abnormality present in hospitalised HIV-infected children. Other abnormalities, although common, were mostly asymptomatic and found with the same frequency in uninfected children. Further studies are indicated.

Nuclear DNA content and chromosome number in some diploid and tetraploid Centaurea (Asteraceae: Cardueae) from the Dalmatia region

Given the paucity of information about genome size in the genus Centaurea, nuclear DNA content of 15 Centaurea taxa, belonging to four subgenera and six different sections, has been investigated for the first time. The sample concerns 21 populations from the Dalmatia region of Croatia. The 2C DNA content and GC percentage were assessed by flow cytometry and chromosome number was determined using standard methods. Genome size of studied Centaurea ranged from 2C=1.67 to 3.72 pg. These results were in accordance with chromosome number and especially with ploidy level that varies throughout this group; 2C DNA values ranged from 1.67 to 3.43 pg for diploid, and from 3.19 to 3.72 for polyploid taxa. No significant intraspecific variations of DNA amount were found between two subspecies of C. visiani and C. ragusina, nor between two varieties of C. gloriosa. However, some populations of C. glaberrima and C. cuspidata showed a significant difference in DNA amount. Three different basic chromosome numbers were observed in studied species (x=9, 10, and 11). The most frequent basic number was x=9. C. rupestris, C. ragusina ssp. ragusina, and C. r. ssp. lungensis possessed x=10 and C. tuberosa x=11. The species with a basic chromosome number of x=9 had a small genome size and the smallest chromosomes (on average 0.09 to 0.12 pg/chromosome) but frequently present polyploidy. Centaurea ragusina ssp. ragusina and C. r. ssp. lungensis had a mean base composition 41.3% GC.

Extreme variability of skeletal and cardiac muscle involvement in patients with mutations in exon 11 of the lamin A/C gene

Mutations of the LMNA gene, encoding the nuclear envelope proteins lamins A and C, give rise to Emery-Dreifuss muscular dystrophy and to limb-girdle muscular dystrophy 1B (EDMD and LGMD1B). With one exception, all the reported EDMD and LGMD1B mutations are confined to the first 10 exons of the gene. We report four separate cases, with mutations in the same codon of LMNA exon 11, characterized by remarkable variability of clinical findings, in addition to features not previously reported. One patient had congenital weakness and died in early childhood. In two other patients, severe cardiac problems arose early and, in one of these, cardiac signs preceded by many years the onset of skeletal muscle weakness. The fourth case had a mild and late-onset LGMD1B phenotype. Our cases further expand the clinical spectrum associated with mutations in the LMNA gene and provide new evidence of the role played by the C-terminal domain of lamin A.

Absence of neuronal nitric oxide synthase (nNOS) as a pathological marker for the diagnosis of Becker muscular dystrophy with rod domain deletions

Immunohistochemistry using antibodies to dystrophin is the pathological basis for the diagnosis of Duchenne and Becker muscular dystrophy (DMD and BMD). While the sarcolemma of DMD muscle is negative, BMD muscle generally shows variable labelling because of the translation of a partially functional dystrophin that is localized to the sarcolemma. In rare cases, however, this labelling is equivocal and similar to that observed in controls making diagnosis difficult. We report here that in such instances immunolabelling with antibodies to the neuronal form of nitric oxide synthase (nNOS) can be useful in suspecting a dystrophinopathy with a mutation in the 'hot-spot' rod domain and help to direct molecular analysis. nNOS localizes to the sarcolemma of mature muscle fibres via several components of the dystrophin-associated protein complex (DAPC) including dystrophin but sarcolemmal nNOS is lost when dystrophin levels are very low or absent because of deletions in critical regions of the rod domain. We report three cases who presented with only mild or no muscle weakness but had elevated serum creatine kinase activity and dystrophin immunolabelling indistinguishable from normal, making a pathological diagnosis difficult. All three cases had a complete absence of sarcolemmal nNOS and were subsequently found to have an in-frame deletion in the common rod domain exons (in these cases 48, 45-51, 47-53) compatible with a BMD. In addition, we observed that nNOS appears to be developmentally regulated with the antibody used and was often absent from the sarcolemma of immature fibres. These findings demonstrate the value of including antibodies to nNOS in routine immunohistochemical studies and that absence of nNOS can be a more sensitive marker than up-regulation of utrophin for diagnosis of BMD. Immaturity of fibres, however, needs to be taken into account, especially in neonates.