Sequestration and biosynthesis of cyanogenic glucosides in passion vine butterflies and consequences for the diversification of their host plants

The colorful heliconiine butterflies are distasteful to predators due to their content of defense compounds called cyanogenic glucosides (CNglcs), which they biosynthesize from aliphatic amino acids. Heliconiine larvae feed exclusively on Passiflora plants where ~30 kinds of CNglcs have been reported. Among them, some CNglcs derived from cyclopentenyl glycine can be sequestered by some Heliconius species. In order to understand the evolution of biosynthesis and sequestration of CNglcs in these butterflies and its consequences for their arms race with Passiflora plants, we analyzed the CNglc distribution in selected heliconiine and Passiflora species. Sequestration of cyclopentenyl CNglcs is not an exclusive trait of Heliconius, since these compounds were present in other heliconiines such as Philaethria, Dryas and Agraulis, and in more distantly related genera Cethosia and Euptoieta. Thus, it is likely that the ability to sequester cyclopentenyl CNglcs arose in an ancestor of the Heliconiinae subfamily. Biosynthesis of aliphatic CNglcs is widespread in these butterflies, although some species from the sara‐sapho group seem to have lost this ability. The CNglc distribution within Passiflora suggests that they might have diversified their cyanogenic profile to escape heliconiine herbivory. This systematic analysis improves our understanding on the evolution of cyanogenesis in the heliconiine–Passiflora system.     

The omnivorous triggerfish Melichthys niger is a functional herbivore on an isolated Atlantic oceanic island

This study evaluated the functional role of the highly generalist omnivore Melichthys niger in the remote St. Peter and St Paul's Archipelago (SPSPA), Brazil, where grazing herbivorous fishes are very scarce. We analysed patterns of distribution from zero to 30 m deep during three time intervals during the day and sampled different aspects of their feeding behaviour, including diel feeding rate, feeding substrate and diet. The density of M. niger increased with depth (26–30 m) and decreased by the end of the day. Although M. niger did not present a typical herbivore diel feeding pattern, they targeted the epilithic algal matrix as their primary feeding substrate, ingesting predominantly algae and detritus. The characteristic Caulerpa racemosa var. peltata from SPSPA was ingested only as detached fronds. We suggest that in the isolated SPSPA, the single species M. niger may perform a unique role as a link between benthic primary production and higher levels. Further studies on the trophic ecology of omnivorous species are necessary to better understand their roles in a reef system, especially in impoverished areas where they are likely to play a crucial role.     

Coupling physiological analysis with proteomic profile to understand the photosynthetic responses of young Euterpe oleracea palms to drought

Photosynthesis Research - This study examined whether drought sensitivity in açaí (Euterpe oleracea Mart.) is associated with reductions in photosynthesis and increasing oxidative stress...     

Occurrence of Atlantic salmon in the Douro River: Recent evidence

Two adult Atlantic salmon, Salmo salar, were netted in 2015 and 2017 during a study conducted in the terminal stretch of the Douro River, after more than 20 years without confirmed records of the species occurrence in the southern limit of its European range. According to professional fisherman operating in the area, a few adult Atlantic salmon are caught every year in this river stretch. Further work should be conducted to assess if the species is reproducing in the Douro River and the overall status of its populations in the North of Iberia.     

Population biology and breeding cycle of the burrowing shrimp Callichirus seilacheri (Decapoda,Callianassidae) from the eastern tropical Pacific

Year-round continuous reproduction in tropical regions is an established paradigm in marine ecology. In this study, we tested this paradigm using the ghost shrimp Callichirus seilacheri from the tropical eastern Pacific as a model species. We also examined size-frequency distribution, sex ratio, and recruitment cycle to contribute to the biological knowledge of this species. To this end, a total of 456 individuals of C. seilacheri were collected during 12 months of sampling. Population structure was symmetrical for both sexes, and the overall sex ratio did not differ from evenness. Males outnumbered females in smaller size classes, though, revealing a potential sex-dependent mortality in small individuals. The breeding pattern followed the well-marked seasonal regime of the region, with ovigerous females registered during the rainy season. While natural variation in the seawater temperature had no influence on reproduction of this species, changes in water salinity possibly triggered the appearance of egg-bearing females in the population. Recruitment occurred throughout the year but was more intense during the dry season, following the appearance of ovigerous females. The adaptability of the life cycle of C. seilacheri to the seasonal climate provides further evidence that reproduction in tropical species is not always continuous.     

4-Deoxyraputindole C induces cell death and cell cycle arrest in tumor cell lines

Several molecules extracted from natural products exhibit different biological activities, such as ion channel modulation, activation of signaling pathways, and anti-inflammatory or antitumor activity. In this study, we tested the antitumor ability of natural compounds extracted from the Raputia praetermissa plant. Among the compounds tested, an alkaloid, here called compound S4 (4-Deoxyraputindole C), showed antitumor effects against human tumor lineages. Compound S4 was the most active against Raji, a lymphoma lineage, promoting cell death with characteristics that including membrane permeabilization, dissipation of the mitochondrial potential, increased superoxide production, and lysosomal membrane permeabilization. The use of cell death inhibitors such as Z-VAD-FMK (caspase inhibitor), necrostatin-1 (receptor-interacting serine/threonine-protein kinase 1 inhibitor), E-64 (cysteine peptidases inhibitor), and N-acetyl- L -cysteine (antioxidant) did not decrease compound S4-dependent cell death. Additionally, we tested the effect of cellular activity on adherent human tumor cells. The highest reduction of cellular activity was observed in A549 cells, a lung carcinoma lineage. In this lineage, the effect on the reduction of the cellular activity was due to cell cycle arrest, without plasma membrane permeabilization, loss of the mitochondrial potential or lysosomal membrane permeabilization. Compound S4 was able to inhibit cathepsin B and L by a nonlinear competitive (negative co-operativity) and simple-linear competitive inhibitions, respectively. The potency of inhibition was higher against cathepsin L. Compound S4 promoted cell cycle arrest at G ₀ and G ₂ phase, and increase the expression of p16 and p21 proteins. In conclusion, compound S4 is an interesting molecule against cancer, promoting cell death in the human lymphoma lineage Raji and cell cycle arrest in the human lung carcinoma lineage A549.     

Sperm cryopreservation of Prochilodus brevis using different concentrations of non-permeable cryoprotectants

The action of substances with non-permeable cryoprotectant potential, besides glucose, has not yet been studied for the species Prochilodus brevis. The objective of this work was to evaluate the action of four non-permeable cryoprotectants on this species sperm cryopreservation. Five pools were cryopreserved in a solution of 5% glucose and 10% dimethyl sulfoxide (Me₂SO) associated or not (control) with cryoprotectants egg yolk (5, 10 or 12%), soy lecithin (2.5, 7.5 or 10%), sucrose (5, 10 or 20%) and lactose (5, 8 or 15%). After thawing, samples were evaluated for sperm kinetics (total motility, motility duration, velocities, and wobble - WOB), morphology and membrane and DNA integrity. The treatments containing egg yolk improved significantly (P<0.05) results when compared the control for the membrane integrity parameter. When compared to other treatments, egg yolk, at any concentration, presented higher results (P<0.05) for membrane integrity, total motility, curvilinear velocity (VCL) and average path velocity (VAP) parameters. Egg yolk also showed the best results for WOB, but it did not differ from 5% and 8% lactose and 5% and 20% sucrose. Soy lecithin had the lowest percentages of morphologically normal sperm (P<0.05), while the other treatments did not differ from each other. There was no difference regarding DNA integrity data. Thus, 5% egg yolk is indicated as a non-permeable cryoprotectant for P. brevis, in association with 5% glucose and 10% Me₂SO.     

The use of ferromagnetic Dacron as solid-phase in chemiluminescent assays

Ferromagnetic Dacron hydrazide particles (63–74 m) were activated either by converting hydrazide groups to azide or binding glutaraldehyde to the hydrazide groups. Human serum albumin (HSA) was immobilised to the activated matrices and antibodies against HSA were detected by using the chemiluminescent assay. The use of these particles (either Dacron-azide or Dacron-glutaraldehyde) gave similar results compared with the paramagnetic particles commercially available from Ciba Corning.     

Requirement for Par-6 and Bazooka in Drosophila border cell migration

Polarized epithelial cells convert into migratory invasive cells during a number of developmental processes, as well as when tumors metastasize. Much has been learned recently concerning the molecules and mechanisms that are responsible for generating and maintaining epithelial cell polarity. However, less is known about what becomes of epithelial polarity proteins when various cell types become migratory and invasive. Here, we report the localization of several apical epithelial proteins, Par-6, Par-3/Bazooka and aPKC, during border cell migration in the Drosophila ovary. All of these proteins remained asymmetrically distributed throughout migration. Moreover, depletion of either Par-6 or Par-3/Bazooka by RNAi resulted in disorganization of the border cell cluster and impaired migration. The distributions of several transmembrane proteins required for migration were abnormal following Par-6 or Par-3/Bazooka downregulation, possibly accounting for the migration defects. Taken together, these results indicate that cells need not lose apical/basal polarity in order to invade neighboring tissues and in some cases even require such polarity for proper motility.