The model arbuscular mycorrhizal fungus Rhizophagus irregularis harbours endosymbiotic bacteria with a highly reduce genome

Arbuscular mycorrhizal fungi (AMF; Glomeromycotina) are symbionts of most plant species that are known to possess unique intracytoplasmic endosymbiotic bacteria with an enigmatic role. Candidatus Moeniiplasma glomeromycotorum (CaMg) was shown to be widespread along the AMF phylogeny and present in most AMF species and isolates of those species. The model AMF species, Rhizophagus irregularis, that can be cultivated in vitro and for which a lot of genomic information now exists, would be the ideal model to study the true nature of the CaMg-AMF symbiosis. However, R. irregularis was never found to host endobacteria. Here we show by DNA sequencing that R. irregularis can, indeed, host CaMg (Ri-CaMg). However, this appears rare as only one R. irregularis isolate out of 58 hosted CaMg. In that isolate, the endosymbiotic bacterial population was genetically homogenous. By sequencing the complete genome of the bacteria, we found that its genome is among the smallest of all known CaMg and Mycoplasma-like genomes, with a highly reduced gene repertoire, suggesting a strong adaptation to the intracellular life. We discuss our findings in the light of previous literature on CaMg and on the same AMF isolates and suggest that these endosymbionts are more likely parasites than non-obligatory mutualists.

Adaptation of Winter Barley Cultivars to Inversion and Non-Inversion Tillage for Yield and Rhynchosporium Symptoms

Modern cereal cultivars are highly adapted to, and normally bred and trialled under, high input, high soil disturbance conditions. On-farm conditions are often suboptimal for high yield and frequently use minimal soil tillage, sometimes no-tillage, and therefore, cultivars may be differentially adapted to such conditions. We report a series of trials across 10 years comparing multiple cultivars within years and smaller numbers across years to identify stable cultivars showing preferential adaptation to different levels of soil tillage. Cultivars responded differentially to inversion and non-inversion tillage but were not affected by the level of cultivation within each of these tillage types. Yield declined over time but much more so in the non-inversion tillage treatment. Rhynchosporium symptoms were also increasingly suppressed in the non-inversion tillage type. Several cultivars were identified that showed strong adaptation to tillage type, and some of these were consistent across several trial years. These cultivars can be used to identify traits and genotypes associated with tillage adaptation to target breeding for on-farm conditions.

Resuscitation of soil microbiota after > 70-years of desiccation

The abundance and diversity of bacteria in 24 historical soil samples under air-dried storage conditions for more than 70 years were assessed by quantification and high-throughput sequencing analysis of 16S rRNA genes. All soils contained a measurable abundance of bacteria varying from 103 to 108 per gram of soil and contrasting community compositions were observed in different background soils, suggesting that the bacteria detected were indigenous to the soil. Following a 4-week soil rewetting event, the bacterial abundance significantly increased in soils, indicating strong adaptation of soil bacteria to extreme osmotic change and high resuscitation potential of some bacteria over long periods of desiccation. Paenibacillus, Cohnella and two unclassified Bacillales genera within the phylum Firmicutes represented the most ubiquitously active taxa, which showed growth in the highest number of soils (≥12 soils), while genera Tumebacillus, Alicyclobacillus and Brevibacillus in the phylum Firmicutes displayed the highest growth rates in soils (with >1000-fold average increase) following rewetting. Additionally, some Actinobacteria and Proteobacteria genera showed relatively high activity following rewetting, suggesting that the resilience to long-term desiccation and rewetting is a common trait across phylogenetically divergent microbes. The present study thus demonstrated that diversified groups of microbes are present and potentially active in historically desiccated soils, which might be of importance in the context of microbial ecology.

Are the Neglected Tipuloidea Crane Flies (Diptera) an Important Component for Subterranean Environments?

Usually, biospeleological studies focus on cave-specialist taxa showing strong adaptation to the subterranean environment, as their unusual morphological and ecological features represent intriguing case studies. On the other hand, species occurring in subterranean environments but without marked adaptations have been generally overlooked, probably because they are thought to be accidental and not very important for the ecosystem. Particularly exemplificative is the case of Tipuloidea crane flies (Diptera), which although abundant, are rarely considered in biospeleological studies. Here, by analyzing the crane fly occupancy, we observed that individuals occur within the shallowest areas of subterranean environments throughout the year, with a peak of presence during hot season. Crane flies occupy dark and warm areas close to the connection with surface and with smoother walls. Furthermore, we observed that the presence of crane flies is positively related to the abundance and the richness of cave predators, highlighting their importance for the sustainment of the local community. With this study we aim to stimulate future researches on these important, but still neglected cave species.

Pittosporum undulatum Vent.: subsidies to the control and management

Pittosporum undulatum (Australian cheesewood) is considered an ornamental species with high invasive potential, due to its strong adaptation capacity to colonize different habitats. Aiming to support controlling management actions, a review of its botanical, ecological, ethnobotanical and silvicultural aspects are presented. Control programs should include this type of information to ensure that the limited resources devoted to this issue will be efficiently allocated. It is important to address holistically the causes of the invasion, particularly the role of the original structure and functional changes imposed on ecosystems and their processes, since colonization by invasive species.

Effects of Alternative Blood Sources on Wolbachia Infected Aedes aegypti Females within and across Generations

Wolbachia bacteria have been identified as a tool for reducing the transmission of arboviruses transmitted by Aedes aegypti. Research groups around the world are now mass rearing Wolbachia-infected Ae. aegypti for deliberate release. We investigated the fitness impact of a crucial element of mass rearing: the blood meal required by female Ae. aegypti to lay eggs. Although Ae. aegypti almost exclusively feed on human blood, it is often difficult to use human blood in disease-endemic settings. When females were fed on sheep or pig blood rather than human blood, egg hatch rates decreased in all three lines tested (uninfected, or infected by wMel, or wAlbB Wolbachia). This finding was particularly pronounced when fed on sheep blood, although fecundity was not affected. Some of these effects persisted after an additional generation on human blood. Attempts to keep populations on sheep and pig blood sources only partly succeeded, suggesting that strong adaptation is required to develop a stably infected line on an alternative blood source. There was a decrease in Wolbachia density when Ae. aegypti were fed on non-human blood sources. Density increased in lines kept for multiple generations on the alternate sources but was still reduced relative to lines kept on human blood. These findings suggest that sheep and pig blood will entail a cost when used for maintaining Wolbachia-infected Ae. aegypti. These costs should be taken into account when planning mass release programs.

Effects of alternative blood sources on Wolbachia infected Aedes aegypti females within and across generations

ABSTRACTWolbachia bacteria have been identified as a tool for reducing the transmission of arboviruses transmitted by Aedes aegypti. Research groups around the world are now mass rearing Wolbachia infected Ae. aegypti for deliberate release. We investigated the fitness impact of a crucial element of mass rearing: the blood meal required by female Ae. aegypti to lay eggs. Although Ae. aegypti almost exclusively feed on human blood, it is often difficult to use human blood in disease-endemic settings. When females were fed on sheep or pig blood rather than human blood, egg hatch rates decreased in all three lines tested (uninfected, or infected by wMel, or wAlbB Wolbachia). This finding was particularly pronounced when fed on sheep blood, although fecundity was not affected. Some of these effects persisted after an additional generation on human blood. Attempts to keep populations on sheep and pig blood sources only partly succeeded, suggesting that strong adaptation is required to develop a stably infected line on an alternative blood source. There was a decrease in Wolbachia density when Wolbachia Ae. aegypti were fed on non-human blood sources, although density was higher again in lines kept for multiple generations on the alternate sources. These findings suggest that sheep and pig blood will entail a cost when used as alternative blood sources which needs to be taken into account when considering mass release.

Effects of invasive species snails in continental aquatic bodies of Pernambucano semiarid

Aim The aim of this study was to survey the species of molluscs and to evaluate the effect of exotic species on the native mollusks of three reservoirs in the Pajeú Basin Cachoeira II, Jazigo and Serrinha. Methods Sampling was carried out with trawl net (5 mm mesh opening) and hand net (2 mm mesh opening). Results and conclusions Were quantified 60,244 specimens, distributed among the species Melanoides tuberculata (49,398), Pomacea lineata (573), Biomphalaria straminea (376) and Physa marmorata (01). The invasive exotic species M. tuberculata was dominant in all reservoirs with a relative abundance greater than 85% and the other species were classified as occasional and rare, with emphasis in Physa marmorata that is present in the red list of species vulnerable to extinction. Regarding the frequency of occurrence, all species were classified as euconstant (occurrence greater than 65%), except P. lineata and P. marmorata, which were classified as ancillary (occurrence less than 40%). Among the species, M. tuberculata were the highest average density (1,636 ind.m-2) in Serrinha reservoir, showed a strong adaptation to the environmental conditions, due to its high dominance in all the reservoirs, being probably the main cause for the low diversity and density indices of native molluscs. Since P. marmorata presented low density and frequency, becoming an important point to be investigated as possible species impaired by the dominance of M. tuberculata.