Conformational stability of recombinant manganese superoxide dismutase from the filamentous fungus Trichoderma reesei

Superoxide dismutases (SODs; EC 1.15.1.1) are part of the antioxidant system of aerobic organisms and are used as a defense against oxidative injury caused by reactive oxygen species (ROS). The cloning and sequencing of the 788-bp genomic DNA from Trichoderma reesei strain QM9414 (anamorph of Hypocrea jecorina) revealed an open reading frame encoding a protein of 212 amino acid residues, with 65-90% similarity to manganese superoxide dismutase from other filamentous fungi. The TrMnSOD was purified and shown to be stable from 20 to 90 °C for 1 h at pH from 8 to 11.5, while maintaining its biological activity.     

Biomass flow and structure of a tropical upwelling ecosystem in La Guajira, Colombian Caribbean

La Guajira is an exploited tropical upwelling ecosystem in the Colombian Caribbean coast. A trophic model of 27 functional groups was constructed using the ECOPATH 5.0 Beta software to integrate the available information on the ecosystem. The model allowed a comparison with other trophic flow models of upwelling ecosystems. Total system biomass (68 t/km2/year), net system production (1,248.5 t/km2/year), and total system throughput (3,275 t/km2/year) make La Guajira moderate when compared with other systems. The largest amount of energy throughput is achieved from trophic level I to II (68.93 %), although an important proportion of the total flow originates from detritus (32 %). The production/respiration ratio exceeds 1, suggesting that La Guajira is an immature ecosystem and is in development, as determined by its low ascendency (33.7 %) and high development capacity (66.3 %), similar to other upwellings that have values of ascendency between 20 % and 35 %. Although the basic input data were good and covered 1995 to 2000, appropriate information is still not available on some trophic groups such as biomass (for phytoplankton, invertebrates, catfishes and pelagic predator fishes), secondary production data (invertebrates, pelagic predator fishes, and small pelagic fishes), and seabird and mammal populations, which are top trophic levels and an essential part of upwelling ecosystems.     

Review. Hybrid trait speciation and Heliconius butterflies

Homoploid hybrid speciation (HHS) is the establishment of a novel species through introgressive hybridization without a change in chromosome number. We discuss different routes by which this might occur and propose a novel term, 'hybrid trait speciation', which combines the idea that hybridization can generate adaptive novelty with the 'magic trait' model of ecological speciation. Heliconius butterflies contain many putative examples of hybrid colour patterns, but only recently has the HHS hypothesis been tested explicitly in this group. Molecular data has shown evidence for gene flow between many distinct species. Furthermore, the colour pattern of Heliconius heurippa can be recreated in laboratory crosses between Heliconius melpomene and Heliconius cydno and, crucially, plays a role in assortative mating between the three species. Nonetheless, although the genome of H. heurippa shows evidence for hybridization, it is not a mosaic of the two parental species. Instead, ongoing hybridization has likely blurred any signal of the original speciation event. We argue that where hybridization leads to novel adaptive traits that also cause reproductive isolation, it is likely to trigger speciation.     

IP3 receptor blockade restores autophagy and mitochondrial function in skeletal muscle fibers of dystrophic mice

Duchenne muscular dystrophy (DMD) is characterized by a severe and progressive destruction of muscle fibers associated with altered Ca²⁺ homeostasis. We have previously shown that the IP₃ receptor (IP₃R) plays a role in elevating basal cytoplasmic Ca²⁺ and that pharmacological blockade of IP₃R restores muscle function. Moreover, we have shown that the IP₃R pathway negatively regulates autophagy by controlling mitochondrial Ca²⁺ levels. Nevertheless, it remains unclear whether IP₃R is involved in abnormal mitochondrial Ca²⁺ levels, mitochondrial dynamics, or autophagy and mitophagy observed in adult DMD skeletal muscle. Here, we show that the elevated basal autophagy and autophagic flux levels were normalized when IP₃R was downregulated in mdx fibers. Pharmacological blockade of IP₃R in mdx fibers restored both increased mitochondrial Ca²⁺ levels and mitochondrial membrane potential under resting conditions. Interestingly, mdx mitochondria changed from a fission to an elongated state after IP₃R knockdown, and the elevated mitophagy levels in mdx fibers were normalized. To our knowledge, this is the first study associating IP₃R1 activity with changes in autophagy, mitochondrial Ca²⁺ levels, mitochondrial membrane potential, mitochondrial dynamics, and mitophagy in adult mouse skeletal muscle. Moreover, these results suggest that increased IP₃R activity in mdx fibers plays an important role in the pathophysiology of DMD. Overall, these results lead us to propose the use of specific IP₃R blockers as a new pharmacological treatment for DMD, given their ability to restore both autophagy/mitophagy and mitochondrial function.     

Behavioral Responses of the Social Wasp Polistes myersi to Prey Infected with Fungi Used in Biological Control

Metarhizium anisopliae and Beauveria bassiana are commonly used entomopathogenic fungi, but their non-target effects over generalist predatory insects, which can contribute to pest control, are not well known. We studied the capacity of the social wasp Polistes myersi to detect the pathogens in either a powdered form or in Galleria mellonella larvae infected with either of the two pathogens offered as prey. The effects of these treatments were compared considering wasp behaviors such as prey preference, frequency, duration and transitions of both hunting and grooming behaviors. Additionally, the effects of each entomopathogenic fungus on the wasp’s mortality were measured. Wasps seem not to detect the pathogens in powdered form but preferred healthy over infected larvae. Seventeen behavioral units for hunting and 34 for grooming were recognized. There were no differences in grooming frequency but there were significant differences on grooming duration, hunting behaviors and the patterns of transitions. Exposure of wasp colonies to either B. bassiana or M. anisopliae had no detectable impact on the mortality of adults, but mortality of larvae increased. For the first time, this study documented behavioral changes that indicated the capacity of social wasps to detect pathogens before physical contact and the display of hygienic strategies once contact occurs. The study also suggested a potential non-target effect of these entomopathogenic fungi on a generalist predator.