First Dutch experience with the endoscopic laser balloon ablation system for the treatment of atrial fibrillation

IntroductionThe endoscopic laser balloon ablation system (EAS) is a relatively novel technique to perform pulmonary vein isolation (PVI) in the treatment of atrial fibrillation (AF). The present study aimed to report the results of the first 50 patients treated in the Netherlands with the EAS in terms of procedural characteristics and AF-free survival.MethodsFifty patients successfully underwent EAS PVI. Median follow-up was 17 months. Mean age was 56 years, 82 % had paroxysmal AF.Results99 % of the pulmonary veins were successfully isolated with the EAS. Mean procedure time was 171 min and mean fluoroscopy time was 36 min. One procedure was complicated by a temporary phrenic nerve palsy (2 %). During follow-up, 58 % of patients remained free of AF without the use of antiarrhythmic drugs.ConclusionPVI with EAS is associated with a low risk of complications and a medium-term AF-free survival comparable with other PVI techniques.

Electronic supplementary material

The online version of this article (doi:10.1007/s12471-014-0624-y) contains supplementary material, which is available to authorized users.     

Host range determination in a novel outbreak pest of sugarcane,Cacosceles newmannii (Coleoptera: Cerambycidae,Prioninae), inferred from stable isotopes

1. An outbreak of Cacosceles newmannii (Coleoptera: Cerambycidae) was detected for the first time on sugarcane (Saccharum spp.) in 2015 in KwaZulu-Natal, South Africa. Although primary host plants of this native species remain unknown, these are central to testing hypotheses concerning the outbreak.
2. We hypothesized that this species has undergone a host plant shift (i.e. a feeding association with a novel host plant).
3. We compared δ¹³C and δ¹⁵N ratios of adult beetles retrieved from South African museum collections, collected between 1891 and 2016 (n = 23; ‘pre-outbreak’), with samples from infested fields in 2017 (n = 9, ‘post-outbreak’) and in 2019 (n = 23, ‘post-outbreak’), as well as diverse, plausible host plants (n = 42 samples across 10 species) from infested fields and surrounding patches of indigenous and commercial forest vegetation. We used Bayesian isotope mixing models to infer the relative contribution of the different plants to the diet of C. newmannii.
4. Pre-outbreak, C₃ plants contributed strongly to the larval diet, whereas post-outbreak, C₄ plants were the largest component of their diet. There was some indication of C₄ plants contributing to their diet pre-outbreak.
5. Our results suggest that the outbreak of this polyphagous beetle was not a dramatic host shift but rather a rapid increase in the proportion of C₄ plants already in their diet.
6. We concluded that plants from the families Fabaceae and Poaceae are the most likely host plants of this species. Nevertheless, the drivers of this rapid outbreak on sugarcane remain poorly determined and should be the focus of future research.

     

Anthropogenic risk increases night-time activities and associations in African elephants (Loxodonta africana) in the Ruaha-Rungwa ecosystem,Tanzania

Elephants face diverse threats from human activities and use temporal and social strategies to reduce human-induced mortality risk. We used data from camera trap surveys in 2018–2019 (n = 1625 independent detection events from 11,751 sampling days) to investigate elephant responses to anthropogenic risk in the Ruaha-Rungwa ecosystem, Tanzania. The study was conducted in one low-risk and three high-risk sites using 26–40 paired camera trap stations per site. Risk influenced the active periods, use of roads and water sources, social associations and behaviour of elephants. Elephants demonstrated significantly more night-time and reduced daytime activity in the high-risk sites relative to the low-risk site. This higher night-time activity in the high-risk sites was observed for both males and females, though it was more pronounced for cow–calf groups than lone males. Foraging events and use of water sources were more frequent at night in the high-risk sites. Elephants used roads as movement routes in the low-risk site but avoided roads in the high-risk sites. Males were significantly more likely to associate with other males and cow–calf groups in the high-risk sites. Fewer occurrences of relaxed behaviours were observed in the high-risk sites compared to the low-risk site. We discuss the potential implications of our findings for elephant survival and reproduction.     

Comparative assessment of heat tolerance in weevils associated with a fire-prone ecosystem

1. Fire is an important cause of disturbance which directly shapes many ecosystems worldwide. While the effect of fire on the distribution and regeneration of plant species has been widely documented, little is known on how phytophagous insects are reacting to these disturbances.
2. This study explores the survival strategies of various weevil species, a highly diverse phytophagous beetle group in fire-prone ecosystems of the biodiversity hotspot of the Cape Floristic Region in South Africa. More specifically, we investigated how the lifestyle of species (location of larval development, phenology of adults, and flight ability) correlates with heat tolerance. We hypothesized that wingless species in particular will show better tolerance to heat as they have a limited ability to escape fire rapidly and usually remain hidden in the soil.
3. The thermal tolerance of a set of sixteen species with divergent lifestyles and geographic distribution was measured using a standard heat knockdown protocol at 48°C. Respirometry was then performed on the most resistant species using a ramping protocol in order to determine CT_max.
4. Our results show that the species tested exhibit high variation in thermal tolerance across taxonomic groups, clustering into three modalities: weak, intermediate, and high tolerance to heat stress. In addition, life history traits (diurnal vs. nocturnal adult activity and location of juvenile stages in plant tissues) likely better explain thermal tolerance at the species level than flight ability or the fire-proneness of ecosystems. Finally, results revealed that some non-flying weevil species are highly heat tolerant with CT_max values reaching up to 50.2 and 51.9°C in species among the Ocladiinae and Brachycerinae subfamilies, respectively.
5. Climate change is leading to an increase in the impact and frequency of fires. In this context, this study highlights the diversity of strategies developed by arthropods to escape extreme heat in fire prone ecosystems. Further work is necessary to examine the generality of these patterns across other fire prone ecosystems to better understand behavioural compensation and evolutionary responses, especially given the forecast increases in fire driven by drying and warming associated with climate change.

     

Detecting coevolution without phylogenetic trees? Tree-ignorant metrics of coevolution perform as well as tree-aware metrics

Background  

Identifying coevolving positions in protein sequences has myriad applications, ranging from understanding and predicting the structure of single molecules to generating proteome-wide predictions of interactions. Algorithms for detecting coevolving positions can be classified into two categories: tree-aware, which incorporate knowledge of phylogeny, and tree-ignorant, which do not. Tree-ignorant methods are frequently orders of magnitude faster, but are widely held to be insufficiently accurate because of a confounding of shared ancestry with coevolution. We conjectured that by using a null distribution that appropriately controls for the shared-ancestry signal, tree-ignorant methods would exhibit equivalent statistical power to tree-aware methods. Using a novel t-test transformation of coevolution metrics, we systematically compared four tree-aware and five tree-ignorant coevolution algorithms, applying them to myoglobin and myosin. We further considered the influence of sequence recoding using reduced-state amino acid alphabets, a common tactic employed in coevolutionary analyses to improve both statistical and computational performance.     

Pollen morphology of Polylepis boyacensis cuatrecasas, Acaena cylindristachya ruiz et pavon and Acaena elongata L. (Rosaceae) and its application to fossil material

The pollenmorphology of recent pollen grains of the species of Polylepis and Acaena (Rosaceae) occurring in the Colombian Cordillera Oriental is described on the basis of light microscopical and scanning electron microscopical study.The results were found to be applicable to the determination of fossil material from lake sediments of last glacial age of the same area.     

Towards Measuring the Informal City: A Societal Metabolism Approach

The rapid growth of urban informal settlements, or slums, poses a particular challenge for balancing developmental and environmental goals. In South Africa, high levels of inequality, poverty, and unemployment contribute to widespread migration. The influx of migrant workers to cities, however, is rarely matched with adequate housing and infrastructure, resulting in the formation and growth of urban informal settlements. Despite the persistence of the slum phenomenon, very few studies provide an in‐depth understanding of the metabolic processes that link these spaces, and informal economies, to the broader urban environment and economy. This article therefore utilized a multiscale integrated assessment of the societal and ecosystem metabolism approach to examine human activity and land use in Enkanini, an urban informal settlement in Stellenbosch, South Africa. The results highlight a number of issues to be addressed through spatial, developmental, and local economic policy, such as the need for improved transport linkages. The time‐use results show that Enkanini is a net provider of labor to the surrounding area. Further, geographical mapping indicates Enkanini as a small, but vibrant, informal economy, while being grossly underserviced in terms of water, waste, and sanitation infrastructure. Key implications are discussed in terms of the theoretical, methodological, societal, and policy impact of the study, including the need for city observatories that conduct regular data collection and analysis.     

Resources driving landscape‐scale distribution patterns of grazers in an African savanna

In order to effectively manage and conserve indigenous herbivores, a good understanding is needed of how resources drive their distribution patterns. This study employed a unique dataset to test a range of ecological theories and hypotheses on free‐ranging grazers. Using aerial census data collected over 14 yr across the 2 million ha Kruger National Park (South Africa), this study employs spatial autologistic regression models to explore the spatial relationships that exist between the distribution of eight indigenous grazer species and a set of resource variables. It was found that ecological theories relating to feeding guild, water‐dependence, allometric scaling, gut‐morphology and vulnerability to predation could explain most of the grazer distribution patterns observed in relation to surface‐water, forage quality, forage quantity and habitat openness. All the grazers studied were water‐dependent and occurred close to a permanent source of water in the dry season. This was ascribed to the lack of moisture in the diet of grazers during the dry season. Most ruminants’ distribution patterns were significantly associated with areas of high forage quality whereas hind‐gut fermentors were neutral towards forage quality. Average forage quantity was not a significant predictor of long‐term, landscape‐scale distribution patterns for any of the grazer species studied. Most small‐ and medium‐bodied grazers preferred open habitats above closed habitats, probably due to higher visibility and a lower predation risk. Large‐bodied grazers did not bias their distribution patterns towards open habitats. The way in which grazers distribute themselves with respect to different resources can potentially inform management actions on appropriate scales.     

From protégé to nurse plant: establishment of thorny shrubs in grazed temperate woodlands

Question: Thorny shrubs play keystone roles in grazed ecosystems by defending non‐protected plants against herbivores, but their establishment in grazed ecosystems is poorly understood. Which factors control establishment of recruits of thorny nurse shrubs in grazed temperate woodlands? Location: Ancient grazed temperate woodlands (52°32′N, 6°36′E), The Netherlands. Methods: We surveyed biotic and abiotic factors for saplings of thorny nurse shrubs in plots with and without saplings. To disentangle these factors, we performed a transplantation experiment over two growing seasons with nurse shrub saplings (Prunus spinosa and Crataegus monogyna) planted in two dominant vegetation types – tall unpalatable swards and short grazed lawns – half of them protected from herbivory via exclosures. Results: Plots with shrub saplings had taller surrounding vegetation, higher soil pH and higher soil moisture than plots without saplings. These plots predominantly contained unpalatable sward species, while plots without saplings mainly contained palatable lawn species. After transplantation, sapling survival was higher in exclosures than in the open, and higher in sward exclosures than in lawn exclosures. Sapling growth was higher in swards than in lawns, higher inside than outside exclosures, and higher for Prunus than Crataegus, while browsing on saplings was higher in lawns. Conclusion: Unpalatable swards form essential establishment niches for thorny shrubs in grazed temperate woodlands: they protect against herbivores before thorns fully develop in saplings, and sapling growth is better due to improved micro‐environmental conditions. Once established and thorny, shrub saplings grow out of the protective range of the swards and in turn facilitate tree seedlings, which are essential for long‐term persistence of grazed temperate woodlands. This study shows that nurse plants may start as protégés before becoming facilitators for other plants in a later life stage. This may be common for nurse plants in various ecosystems. We argue that improved understanding of establishment of nurse plants and their constraining factors is crucial for effective conservation and restoration in various ecosystems.