Avian life-history determinants of local extinction risk in a hyper-fragmented neotropical forest landscape

The fact that species vary in their vulnerability to extinction is well documented, but the reasons for these differences remain poorly understood. Why should some species/families/guilds decline rapidly with increasing anthropogenic disturbance, while others either tolerate or proliferate in disturbed habitats? We investigated the bird species composition in 31 primary forest patches of varying size in a region of the Amazonian 'Arc of Deforestation' and assessed which species life-history traits predisposed individual species to extinction. Medium-sized non-flocking canopy frugivores/ominvores of low primary forest dependence were least likely to go extinct in small patches, while small-bodied flock-following primary-forest-dependent terrestrial insectivores were most fragmentation sensitive. We found highly idiosyncratic relationships between the minimum size of forest patches occupied by different species and their territory size requirements estimated based on other Amazonian studies. This suggests that avian assemblages in forest fragments primarily comprise species that either have good dispersal abilities or are highly tolerant to the non-forest matrix, rather than those whose minimum spatial requirements can be met by the size of available forest fragments.     

Individual tree context and contrast dictate tree physiological features and arthropod biodiversity patterns across multiple trophic levels

1. The present study tested the hypothesis that tree context (natural, semi-natural or planted) and contrast (height of surrounding vegetation) affect tree physiological characters (leaf size, nutrient content, and stress-related factors), and also alter the arthropod biodiversity patterns either directly or indirectly. 2. Arthropods were collected from tree canopies using chemical fogging from the ecologically important South African native tree Podocarpus elongatus. 3. Low contrast trees had significantly larger leaves than those in high contrast environments and harboured an overall higher richness, abundance, and biomass of arthropods, although this was guild-dependent. 4. Trees in natural contexts had less foliar δ¹³C, suffered less from artificial nitrogen enrichment, and harboured significantly higher herbivore and predator arthropod richness and unique assemblages, compared with planted trees. 5. Semi-natural trees supported natural levels of arthropod richness, although these were mostly generalist species. 6. Tree context and contrast can therefore dictate associated biota at multiple trophic levels and native trees may fail to maintain natural biodiversity in transformed landscapes.     

Reproduction of the rare monocarpic species Saxifraga mutata L.

The aim of the study is to investigate the impact of reproduction and genetic variation on the persistence of populations of the prealpine, monocarpic Saxifraga mutata L. The species grows on erosion slopes or rocks, and its local populations are often small and isolated. Crossing experiments resulted in better seed-set than selfing, but both yielded viable seeds. Agamospermy did not occur. In an early-successional species like S. mutata , successful selfing is important in the colonization of new habitats. Flowers of S. mutata were visited by Syrphidae and unspecialized Hymenoptera. A germination rate of 40% was reached in cultivation after 20 weeks but germination continued until the end of the experiment after 92 weeks. Seeds stored dry for 30 months at room temperature mostly lost their germinability. In natural habitats, seedlings were found almost throughout the year with a peak in spring. Suitable safe sites were small patches of open soil, bare marl on erosion slopes, and rock crevices. AU individuals investigated were diploid with 2n = 26. Allozyme electrophoresis showed a lack of segregation within the populations. Intra- and interpopulation genetic variation was low. These results were in partial disagreement with theoretical expectations in a mixed mating species. It is concluded that demographic rather than genetic processes are the main cause of extinction of populations of S. mutata , at least in the short-term.     

Lysine Succinylation of VBS Contributes to Sclerotia Development and Aflatoxin Biosynthesis in Aspergillus flavus

Aspergillus flavus is a common saprophytic and pathogenic fungus, and its secondary metabolic pathways are one of the most highly characterized owing to its aflatoxin (AF) metabolite affecting global economic crops and human health. Different natural environments can cause significant variations in AF synthesis. Succinylation was recently identified as one of the most critical regulatory post-translational modifications affecting metabolic pathways. It is primarily reported in human cells and bacteria with few studies on fungi. Proteomic quantification of lysine succinylation (Ksuc) exploring its potential involvement in secondary metabolism regulation (including AF production) has not been performed under natural conditions in A. flavus. In this study, a quantification method was performed based on tandem mass tag labeling and antibody-based affinity enrichment of succinylated peptides via high accuracy nano-liquid chromatography with tandem mass spectrometry to explore the succinylation mechanism affecting the pathogenicity of naturally isolated A. flavus strains with varying toxin production. Altogether, 1240 Ksuc sites in 768 proteins were identified with 1103 sites in 685 proteins quantified. Comparing succinylated protein levels between high and low AF-producing A. flavus strains, bioinformatics analysis indicated that most succinylated proteins located in the AF biosynthetic pathway were downregulated, which directly affected AF synthesis. Versicolorin B synthase is a key catalytic enzyme for heterochrome B synthesis during AF synthesis. Site-directed mutagenesis and biochemical studies revealed that versicolorin B synthase succinylation is an important regulatory mechanism affecting sclerotia development and AF biosynthesis in A. flavus. In summary, our quantitative study of the lysine succinylome in high/low AF-producing strains revealed the role of Ksuc in regulating AF biosynthesis. We revealed novel insights into the metabolism of AF biosynthesis using naturally isolated A. flavus strains and identified a rich source of metabolism-related enzymes regulated by succinylation.     

An annotated checklist of the fish fauna of the river systems draining the Kahuzi-Biega National Park (Upper Congo: Eastern DR Congo)

The Kahuzi-Biega National Park (KBNP), situated mainly in the Eastern Highlands Ecoregion of the Upper Congo basin, is drained by the Lowa and Ulindi rivers, and some western affluents of Lake Kivu. In this study, the first list of the fish diversity of these systems is provided based on museum collections and complemented, for the Lowa River system and the western Lake Kivu affluents, with recently collected specimens (2013–2017). A total of 118 species are reported from the Lowa basin, 22 from the Ulindi basin and seven from these Lake Kivu affluents. Within the Lowa and Ulindi, respectively, five and one species, all cichlids, have been introduced. Currently, 51 species are reported from within the park, only two of which have been reported from the highlands, i.e., Amphilius kivuensis from the Luha, the source of the Luka River, and Clarias liocephalus from the headwaters of the Lake Kivu’ affluents. With a total of 30 species, Cyprinidae is by far the largest family, representing 25% of the total species diversity of the Lowa basin. It is followed by Mormyridae with 13 species (11%), Alestidae and Mochokidae with 10 species each (8%), Clariidae and Amphiliidae with eight species (7%), and Distichodontidae with six species (5%). Seven new species for science were discovered and 11 species were found to be endemic to the Lowa system. Although further exploration is needed, this underscores the importance of the KBNP in protecting the fish fauna of the Lowa basin but also highlights the park's limited coverage of the fish fauna of the Lowa basin.     

Biodiversity in the Gulf of Guinea: an overview

Patterns of species-richness and endemism in the Gulf of Guinea reflect the region's biogeographic history. Bioko is a continental-shelf island that was recently connected to the African mainland, whereas Príncipe, São Tomé and Annobón are truly oceanic and have never been connected with each other or with the mainland. As a result, Bioko supports a much more diverse flora and fauna but with relatively low levels of endemism at the species level, whereas the oceanic islands are relatively depauperate because of their isolation but rich in endemic taxa. Species endemism is 0–3% on Bioko for angiosperms, bats, birds, reptiles and amphibians, compared with much higher values on Principe for these same taxa of 8% (plants) to 100% (amphibians), on São Tomé between 14% (plants) and 100% (amphibians), and on Annobón 0% (bats) to 71% (reptiles). On a global scale, for their size both Príncipe and São Tomé support unusually high numbers of single-island endemic species of birds, reptiles and amphibia. For its tiny size, Annobón is also notable for its endemic birds and reptiles. Among terrestrial molluscs the rates of endemism are in general higher than for plants and vertebrates, from ca 50% on Bioko to ca 80% on the oceanic islands. In contrast and as might be expected, only Bioko supports a rich freshwater fish fauna and it contains many endemic taxa, whereas the oceanic islands support only a few salt-tolerant species. The Gulf of Guinea islands are also important for their marine organisms, amongst which coral reef fish and marginellid molluscs show high levels of endemism, though they are not especially species-rich. The Gulf of Guinea islands are of great interest to conservationists and evolutionary biologists. Each island, of greatly differing size and degree of isolation, has acquired its unique sub-set of plants and animals separately from the neighbouring mainland, followed by adaptive radiations in situ. For this reason the conservation value of the archipelago as a whole is greater than the sum of the biodiversity contained in its individual islands. Conservation initiatives in the Gulf of Guinea should therefore ensure that representative terrestrial, freshwater and marine habitats and groups of organisms are targeted in a co-ordinated manner among the islands.     

P300 Interacted With N-Myc and Regulated Its Protein Stability via Altering Its Post-Translational Modifications in Neuroblastoma

MYCN amplification is an independent risk factor for poor prognosis in neuroblastoma (NB), but its protein product cannot be directly targeted because of protein structure. Thus, this study aimed to explore novel ways to indirectly target N-Myc by regulating its post-translational modifications (PTMs) and therefore protein stability. N-Myc coimmunoprecipitation combined with HPLC–MS/MS identified 16 PTM residues and 114 potential N-Myc-interacting proteins. Notably, both acetylation and ubiquitination were identified on lysine 199 of N-Myc. We then discovered that p300, which can interact with N-Myc, modulated the protein stability of N-Myc in MYCN-amplified NB cell lines and simultaneously regulated the acetylation level and ubiquitination level on lysine-199 of N-Myc protein in vitro. Furthermore, p300 correlated with poor prognosis in NB patients. Taken together, p300 can be considered as a potential therapeutic target to treat MYCN-amplified NB patients, and other identified PTMs and interacting proteins also provide potential targets for further study.     

Alien plants of coastal dune habitats in southern Spain

Alien plants from psammophilous ecosystems have been studied in southern Spain. Sixteen sites, which are included in the Andalusian Network of Protected Spaces, have been chosen along 1100 km of Andalusian coasts in order to verify the degree of abundance and influence of these species on different communities. Out of the 26 localized species, the increase of some invasive plants, such as Arctotheca calendula, Agave americana, A. sisalana, Cortaderia selloana, Lantana camara and Opuntia dillenii, affects the conservation of some natural coastal ecosystems.     

Vitrification of collared peccary ovarian tissue using open or closed systems and different intracellular cryoprotectants

This study aimed to evaluate different vitrification methods using distinct cryoprotectants (CPAs) for the preservation of collared peccary ovarian preantral follicles (PFs). Ovarian pairs from six females were fragmented and three fragments (fresh control group) were immediately evaluated for morphology, viability, cell proliferation capacity (assessed by quantifying the number of argyrophilic nucleolus organizer regions – NORs), and apoptosis (by the identification of activated caspase-3 expression). The remaining 18 fragments were vitrified using the solid surface vitrification (SSV) method or the ovarian tissue cryosystem (OTC) with 3 M ethylene glycol (EG), 3 M dimethylsulfoxide (DMSO), or a combination of the two (1.5 M EG/1.5 M DMSO). After two weeks, samples were rewarmed and evaluated as described previously. The OTC with any of the CPAs provided a similar conservation of morphologically normal PFs as the fresh control group (75.6 ± 8.6%); however, the SSV was only efficient with DMSO alone (63.9 ± 7.6%). Regarding the viability or cell proliferation, all tested groups provided post rewarming values similar to those observed for the fresh control group, 84.0 ± 2.9% viable cells with 2.0 ± 0.2 NORs. Related to apoptosis analysis, only the OTC with EG (46.7%) and the SSV method with EG (43.4%) or the combination of EG and DMSO (33.4%) provided similar values to those found for the fresh control group (36.7%). Our findings indicate the utilization of a closed system, the OTC, with 3 M EG as the CPA for the vitrification of collared peccary ovarian tissue.