Factors Influencing the Survival of Sympatric Gorilla (<Emphasis Type="Italic">Gorilla gorilla gorilla</Emphasis>) and Chimpanzee (<Emphasis Type="Italic">Pan troglodytes troglodytes</Emphasis>) Nests

Accurate and precise surveys of primate abundance provide the basis for understanding species ecology and essential information for conservation assessments. Owing to the elusive nature of wild apes and the vast region of dense forest they inhabit, population estimates of central chimpanzees (Pan troglodytes troglodytes) and western lowland gorillas (Gorilla gorilla gorilla) have largely relied on surveys of their nests. Specific information about the nesting behavior of apes permits the estimation of the number of nests built (nest creation rate). Similarly, information on nest characteristics and environmental factors can be used to estimate the time it takes nests to decay (nest decay rate). Nest creation and decay rates are then used to convert nest density estimates to absolute ape densities. Population estimates that use site-specific estimates of nest creation and decay rates are more accurate and precise. However, it is common practice to generalize these conversion factors across sites because of the additional cost of studies required to gather the information to estimate them. Over a 9-mo study period, we detected and monitored the time to decay of gorilla nests (N = 514) and chimpanzee nests (N = 521) in northern Republic of Congo. We investigated the influence of nest characteristics and environmental factors on nest survivorship and estimated the mean time to nest decay (or equivalently survival) using MARK. Key factors influencing nest decay rate included ape species, forest type, nest height, mean rainfall, nest structure, nest type, and primary aspects of nest construction. Our findings highlight the synergistic effect of behavior and environment on great ape nest degradation, as well as providing practical insights for improving measures to monitor remaining populations of these endangered species.     

Relationships Between Adult Male and Maturing Mountain Gorillas (Gorilla beringei beringei) Persist Across Developmental Stages and Social Upheaval

Across the animal kingdom, long‐term social relationships outside the context of reproductive pair bonds are rare. However, they have been demonstrated in some mammals including primates, cetaceans, and social carnivores. The ontogeny of such relationships is likely to depend on the benefits individuals can gain by cultivating them. Previous studies demonstrated that young mountain gorillas (Gorilla beringei beringei) have strong relationships with adult males, but little is known about the longevity of these bonds. Here, we examine the temporal stability of proximity relationships between coresident adult male and maturing gorillas in the habituated population monitored by the Dian Fossey Gorilla Fund International's Karisoke Research Center in Volcanoes National Park, Rwanda. We used spatial proximity data to assess the strength of relationships between adult males and juveniles, and tracked these relationships as the juveniles matured into subadults (3–4 yr later; n = 229 dyads) and then young adults (7 yr later; n = 42 dyads). The proximity relationships of juveniles of both sexes predicted their proximity relationships with adult males in both subadulthood and young adulthood. However some young adult males who had lost their top adult male proximity partner from juvenilehood developed new relationships with older males that had risen in the dominance hierarchy. These data suggest that (1) kin selection may play a more important role in social relationships between potential fathers and adult female offspring than previously suspected, and (2) when maturing males' foremost adult male social partners remain available to them, their relationships can be stable past the age at which younger males become reproductive competitors.     

Impact of food processing and detoxification treatments on mycotoxin contamination

Mycotoxins are fungal metabolites commonly occurring in food, which pose a health risk to the consumer. Maximum levels for major mycotoxins allowed in food have been established worldwide. Good agricultural practices, plant disease management, and adequate storage conditions limit mycotoxin levels in the food chain yet do not eliminate mycotoxins completely. Food processing can further reduce mycotoxin levels by physical removal and decontamination by chemical or enzymatic transformation of mycotoxins into less toxic products. Physical removal of mycotoxins is very efficient: manual sorting of grains, nuts, and fruits by farmers as well as automatic sorting by the industry significantly lowers the mean mycotoxin content. Further processing such as milling, steeping, and extrusion can also reduce mycotoxin content. Mycotoxins can be detoxified chemically by reacting with food components and technical aids; these reactions are facilitated by high temperature and alkaline or acidic conditions. Detoxification of mycotoxins can also be achieved enzymatically. Some enzymes able to transform mycotoxins naturally occur in food commodities or are produced during fermentation but more efficient detoxification can be achieved by deliberate introduction of purified enzymes. We recommend integrating evaluation of processing technologies for their impact on mycotoxins into risk management. Processing steps proven to mitigate mycotoxin contamination should be used whenever necessary. Development of detoxification technologies for high-risk commodities should be a priority for research. While physical techniques currently offer the most efficient post-harvest reduction of mycotoxin content in food, biotechnology possesses the largest potential for future developments.     

Genomic and physiological analysis reveals versatile metabolic capacity of deep-sea <Emphasis Type="Italic">Photobacterium phosphoreum</Emphasis> ANT-2200

Bacteria of the genus Photobacterium thrive worldwide in oceans and show substantial eco-physiological diversity including free-living, symbiotic and piezophilic life styles. Genomic characteristics underlying this variability across species are poorly understood. Here we carried out genomic and physiological analysis of Photobacterium phosphoreum strain ANT-2200, the first deep-sea luminous bacterium of which the genome has been sequenced. Using optical mapping we updated the genomic data and reassembled it into two chromosomes and a large plasmid. Genomic analysis revealed a versatile energy metabolic potential and physiological analysis confirmed its growth capacity by deriving energy from fermentation of glucose or maltose, by respiration with formate as electron donor and trimethlyamine N-oxide (TMAO), nitrate or fumarate as electron acceptors, or by chemo-organo-heterotrophic growth in rich media. Despite that it was isolated at a site with saturated dissolved oxygen, the ANT-2200 strain possesses four gene clusters coding for typical anaerobic enzymes, the TMAO reductases. Elevated hydrostatic pressure enhances the TMAO reductase activity, mainly due to the increase of isoenzyme TorA1. The high copy number of the TMAO reductase isoenzymes and pressure-enhanced activity might imply a strategy developed by bacteria to adapt to deep-sea habitats where the instant TMAO availability may increase with depth.     

There's no place like home: seedling mortality contributes to the habitat specialisation of tree species across Amazonia

Understanding the mechanisms generating species distributions remains a challenge, especially in hyperdiverse tropical forests. We evaluated the role of rainfall variation, soil gradients and herbivory on seedling mortality, and how variation in seedling performance along these gradients contributes to habitat specialisation. In a 4‐year experiment, replicated at the two extremes of the Amazon basin, we reciprocally transplanted 4638 tree seedlings of 41 habitat‐specialist species from seven phylogenetic lineages among the three most important forest habitats of lowland Amazonia. Rainfall variation, flooding and soil gradients strongly influenced seedling mortality, whereas herbivory had negligible impact. Seedling mortality varied strongly among habitats, consistent with predictions for habitat specialists in most lineages. This suggests that seedling performance is a primary determinant of the habitat associations of adult trees across Amazonia. It further suggests that tree diversity, currently mostly harboured in terra firme forests, may be strongly impacted by the predicted climate changes in Amazonia.     

Surface polysaccharides and quorum sensing are involved in the attachment and survival of Xanthomonas albilineans on sugarcane leaves

Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is a bacterial plant pathogen that is mainly spread by infected cuttings and contaminated harvesting tools. However, some strains of this pathogen are known to be spread by aerial means and are able to colonize the phyllosphere of sugarcane before entering the host plant and causing disease. The objective of this study was to identify the molecular factors involved in the survival or growth of X. albilineans on sugarcane leaves. We developed a bioassay to test for the attachment of X. albilineans on sugarcane leaves using tissue‐cultured plantlets grown in vitro. Six mutants of strain XaFL07‐1 affected in surface polysaccharide production completely lost their capacity to survive on the sugarcane leaf surface. These mutants produced more biofilm in vitro and accumulated more cellular poly‐β‐hydroxybutyrate than the wild‐type strain. A mutant affected in the production of small molecules (including potential biosurfactants) synthesized by non‐ribosomal peptide synthetases (NRPSs) attached to the sugarcane leaves as well as the wild‐type strain. Surprisingly, the attachment of bacteria on sugarcane leaves varied among mutants of the rpf gene cluster involved in bacterial quorum sensing. Therefore, quorum sensing may affect polysaccharide production, or both polysaccharides and quorum sensing may be involved in the survival or growth of X. albilineans on sugarcane leaves.     

Display of whole proteins on inner and outer surfaces of grapevine fanleaf virus‐like particles

Virus‐like particles (VLPs) derived from nonenveloped viruses result from the self‐assembly of capsid proteins (CPs). They generally show similar structural features to viral particles but are noninfectious and their inner cavity and outer surface can potentially be adapted to serve as nanocarriers of great biotechnological interest. While a VLP outer surface is generally amenable to chemical or genetic modifications, encaging a cargo within particles can be more complex and is often limited to small molecules or peptides. Examples where both inner cavity and outer surface have been used to simultaneously encapsulate and expose entire proteins remain scarce. Here, we describe the production of spherical VLPs exposing fluorescent proteins at either their outer surface or inner cavity as a result of the self‐assembly of a single genetically modified viral structural protein, the CP of grapevine fanleaf virus (GFLV). We found that the N‐ and C‐terminal ends of the GFLV CP allow the genetic fusion of proteins as large as 27 kDa and the plant‐based production of nucleic acid‐free VLPs. Remarkably, expression of N‐ or C‐terminal CP fusions resulted in the production of VLPs with recombinant proteins exposed to either the inner cavity or the outer surface, respectively, while coexpression of both fusion proteins led to the formation hybrid VLP, although rather inefficiently. Such properties are rather unique for a single viral structural protein and open new potential avenues for the design of safe and versatile nanocarriers, particularly for the targeted delivery of bioactive molecules.     

Engineering high α‐amylase levels in wheat grain lowers Falling Number but improves baking properties

Late maturity α‐amylase (LMA) and preharvest sprouting (PHS) are genetic defects in wheat. They are both characterized by the expression of specific isoforms of α‐amylase in particular genotypes in the grain prior to harvest. The enhanced expression of α‐amylase in both LMA and PHS results in a reduction in Falling Number (FN), a test of gel viscosity, and subsequent downgrading of the grain, along with a reduced price for growers. The FN test is unable to distinguish between LMA and PHS; thus, both defects are treated similarly when grain is traded. However, in PHS‐affected grains, proteases and other degradative process are activated, and this has been shown to have a negative impact on end product quality. No studies have been conducted to determine whether LMA is detrimental to end product quality. This work demonstrated that wheat in which an isoform α‐amylase (TaAmy3) was overexpressed in the endosperm of developing grain to levels of up to 100‐fold higher than the wild‐type resulted in low FN similar to those seen in LMA‐ or PHS‐affected grains. This increase had no detrimental effect on starch structure, flour composition and enhanced baking quality, in small‐scale 10‐g baking tests. In these small‐scale tests, overexpression of TaAmy3 led to increased loaf volume and Maillard‐related browning to levels higher than those in control flours when baking improver was added. These findings raise questions as to the validity of the assumption that (i) LMA is detrimental to end product quality and (ii) a low FN is always indicative of a reduction in quality. This work suggests the need for a better understanding of the impact of elevated expression of specific α‐amylase on end product quality.     

A role for septin 2 in Drp1‐mediated mitochondrial fission

Mitochondria are essential eukaryotic organelles often forming intricate networks. The overall network morphology is determined by mitochondrial fusion and fission. Among the multiple mechanisms that appear to regulate mitochondrial fission, the ER and actin have recently been shown to play an important role by mediating mitochondrial constriction and promoting the action of a key fission factor, the dynamin‐like protein Drp1. Here, we report that the cytoskeletal component septin 2 is involved in Drp1‐dependent mitochondrial fission in mammalian cells. Septin 2 localizes to a subset of mitochondrial constrictions and directly binds Drp1, as shown by immunoprecipitation of the endogenous proteins and by pulldown assays with recombinant proteins. Depletion of septin 2 reduces Drp1 recruitment to mitochondria and results in hyperfused mitochondria and delayed FCCP‐induced fission. Strikingly, septin depletion also affects mitochondrial morphology in Caenorhabditis elegans, strongly suggesting that the role of septins in mitochondrial dynamics is evolutionarily conserved.