Attractiveness of dung beetles (Coleoptera: Scarabaeinae) to faeces from native mammals in different trophic guilds

Dung beetles are predominantly coprophagous and use mammalian faeces as their main food resource and for offspring rearing. However, these resources are generally ephemeral and scarce. The objective of this study was to verify the attractiveness to dung beetles of the faeces of nine native mammal species of the Cerrado biome in different trophic guilds. This study was conducted during the rainy season (October 2016 to March 2017) in two sensu stricto areas of the Cerrado in the Brasília National Park (PNB), Federal District, Brazil. Pitfalls containing faeces of nine mammals native to the region were used as bait (from three herbivores, three carnivores and three omnivores) for the collection of dung beetles. We collected 203 individuals and 19 species, and the most abundant species were Uroxys aff. thoracalis, Oxysternon palemo, Coprophanaeus spitzi and Diabroctis mirabilis. The most attractive faecal bait was from the omnivorous Chrysocyon brachyurus (32.67% of the individuals and 13 species). This study reveals variation in the attraction of dung beetles to native mammal dung of the Cerrado, with more abundance in the faeces of omnivores and carnivores and less in the faeces of herbivores. The species composition in the carnivore baits did not differ from that of the omnivore baits. These data indicate that changes in Scarabaeinae assemblages result from changes in mammal species such as those that have occurred in the Cerrado biome with the conversion to cattle production, which in recent years has caused intense fragmentation of habitats, expansion of agricultural and livestock activities and the introduction of exotic species. The mammal C. brachyurus, vulnerable to extinction in Brazil, should be a focus for future research, since its faeces support a great diversity of dung beetles in the Cerrado.     

Anti-Inflammatory Activity of Lauraceae Plant Species and Prediction Models Based on Their Metabolomics Profiling Data

The Lauraceae is a botanical family known for its anti-inflammatory potential. However, several species have not yet been studied. Thus, this work aimed to screen the anti-inflammatory activity of this plant family and to build statistical prediction models. The methodology was based on the statistical analysis of high-resolution liquid chromatography coupled with mass spectrometry data and the ex vivo anti-inflammatory activity of plant extracts. The ex vivo results demonstrated significant anti-inflammatory activity for several of these plants for the first time. The sample data were applied to build anti-inflammatory activity prediction models, including the partial least square acquired, artificial neural network, and stochastic gradient descent, which showed adequate fitting and predictive performance. Key anti-inflammatory markers, such as aporphine and benzylisoquinoline alkaloids were annotated with confidence level 2. Additionally, the validated prediction models proved to be useful for predicting active extracts using metabolomics data and studying their most bioactive metabolites.     

Ant diversity decreases during the dry season: A meta-analysis of the effects of seasonality on ant richness and abundance

Tropical studies traditionally describe insect diversity variation throughout the year. The temporally structured responses of insect assemblages to climate seasonality vary across ecosystems due to gradients of resource availability and limiting ecological factors. These idiosyncratic responses might be particularly true across the vast geographical range of the Brazilian territory, including various environments that harbor one of the most diverse ant faunas worldwide. This study addressed the relationship between ant diversity and climatic seasonality, performing a quantitative review of the published data on ant diversity collected in Brazil. We investigated the seasonality effect on ant abundance and richness described in the literature in 47 papers published between 2000 and 2018. These studies were developed mainly in the Atlantic Forest biome and collected ants with pitfall traps on the soil/litter stratum. We initially carried out a vote-counting procedure by comparing the number of significant results describing seasonal differences in the ant assemblage. We found that most papers described a similar pattern of ant abundance, richness, and species composition between seasons. However, when we performed a meta-analysis, we observed a clear pattern of higher ant abundance and richness in the wet/summer season compared with the dry/winter season. Our meta-analysis reveals that the ant diversity decreases in the dry season, strongly in the Cerrado biome. Additionally, we point out differences in the sampling effort across biomes, indicating the need for further investments in studies focused on temporal diversity patterns, including seasonal effects, on the insect assemblage in biomes less investigated so far. Abstract in Portuguese is available with online material.     

Amino acid sequence of piratoxin-I, a myotoxin fromBothrops pirajai snake venom, and its biological activity after alkylation withp-bromophenacyl bromide

The complete sequence of the 121 amino acid residues of piratoxin-I (PrTX-I), a phospholipase A₂ (PLA₂)-like myotoxin fromBothrops pirajai snake (Bahia jararacussu) venom, is reported. From the sequence, anM _r of 13,825 and an approximatepI of 8.3 were calculated. PrTX-I shows a high sequence homology with Lys-49 myotoxins from other bothropic (∼95%) and nonbothropic (∼80%) venoms, but only 70–75% homology w hen aligned with the catalytically active Asp-49 PLA₂s. When compared with bothropstoxin-I fromBothrops jararacussu, which is morphologically almost identical toB. pirajai, only two changes out of 121 total amino acid residues have been observed. The approximate minimal lethal doseLD ₅₀ (mice, i.p., 24 hr) of PrTX-I was 8 (6.8–9.1) mg/kg, and the minimal edematogenic dose (MED) in a rat paw model was 39.5±1.8 ug. After alkylation of His-48 withp-bromophenacyl bromide, the MED was 40.1±1.9 ug, but up to 4LD ₅₀ were unable to cause death in any of a group of eight mice after 72 hr. Therefore the edematogenic activity was retained and apparently did not involve His-48, suggesting that at least two biologically active sites are present in PrTX-I.     

Pyrrolizidine alkaloids: different acquisition and use patterns in Apocynaceae and Solanaceae feeding ithomiine butterflies (Lepidoptera: Nymphalidae)

Pyrrolizidine alkaloids (PAs) often serve as chemical mediators of plant-herbivore-predator interactions. Butterflies (Danainae and Ithomiinae) and moths (Arctiidae) usually acquire PAs from plant sources (larval host plants, flowers or withered leaves visited by adults—pharmacophagy) and thereby become chemically protected against predators; they also use PAs as pheromone precursors. Study by GC-MS of PAs in three species of Ithomiinae butterflies, their larval host plants and adult alkaloid sources showed three different acquisition patterns: (1) larvae of the primitive Tithorea harmonia sequester PAs from their food plant Prestonia acutifolia (Apocynaceae: Echitoideae), and adults may also acquire these alkaloids from plant sources; (2) larvae of the more derived Aeria olena feed on Prestonia coalita , in whose leaves no PAs were detected, but freshly emerged adults sometimes contain PAs and males intensively seek and sequester these alkaloids in plant sources; and (3) larvae of the still more advanced Mechanitis polymnia feed on several PA-free Solanum species, and adult males sequester the alkaloids from various plant sources. Males and females of all three species contain mostly two PAs, the diastereoisomeric retronecine monoesters lycopsamine and intermedine, stored in the N-oxide form. Larval host plants and adult plant sources showed a large array of PA structures, the most abundant and frequent being lycopsamine and its diastereoisomers intermedine, echinatine, rinderine and indicine, and the deoxy-analogues supinine and amabiline. Bioassays with wild caught and freshly emerged adults suggest that protection against predation by the orb weaving spider Nephila clavipes may be dependent on PA concentration and maybe some spider idiosyncrasies, but freshly emerged Aeria olena without PAs are also liberated by Nephila , suggesting other protective compounds. The role of this spider as a selective pressure for PA acquisition by ithomiines is not clear.     

Growth-promoting factors for yeast cells ofParacoccidioides brasiliensis

Low-density seedings of yeast cells ofParacoccidioides brasiliensis give poor growth (as assessed by plating efficiency test) on conventional mycological agar media, and therefore growth-promoting factors for this fungus were sought. Water-extracts of yeast cells of sixP. brasiliensis isolates were all considerably effective in promoting the growth of low-density seedings ofP. brasiliensis isolates Pb-18 and Hachisuga, but had little effect on isolate Bt-4. Horse serum, at a concentration range of 2–4%, moderately or considerably promoted the growth of theseP. brasiliensis isolates. Combinations of the fungus cell extracts with horse serum were highly effective in promoting the growth of all of the fungal isolates. The fungus cell extracts showed siderophore (microbial iron carrier) activity. An iron-chelator, ethylenediaminetetraacetic acid, at a concentration of 100 μM also highly promoted the growth of the fungal isolates in the presence of horse serum, and ferric ion added to culture medium was considerably effective in the growth promotion. These results suggest that deficient utilization of external iron by the fungus cell is one of the growth-limiting processes for low-density seedings of yeast cells ofP. brasiliensis on conventional mycological agar media.     

Effect of X-radiation on DNA and histone synthesis in ataxia telangiectasia and normal lymphoblastoid cells

The possibility that the radiosensitivity of lymphoblastoid cell lines from patients with ataxia telangiectasia (A-T) is due to an aberrant content of histones has been examined. The histone pattern of lymphoblastoid cell lines derived from A-T patients was found to be indistinguishable from that obtained from normal individuals. X-ray irradiation led to a greater decrease in cell growth rate in the A-T cells than in the normal cells but was accompanied by a greater decrease of DNA synthesis rate in the normal cells. This difference in radiosensitivity was not reflected in differences in the content or rates of synthesis of histones or of major non-histone proteins in these cells. Reduction in the rate of DNA synthesis was not associated with the appearance of the lysine-rich histone variant H1. We conclude that the hypersensitivity to ionizing radiation in A-T cells is not due to fundamental differences in the composition or synthesis of the major chromosomal proteins.     

Localization of placental lactogen-I in trophoblast giant cells of the mouse placenta

The purpose of this investigation was to identify the cellular origin of placental lactogen-I (PL-I) expression in the mouse placenta and to cytologically define the transition from PL-I to PL-II expression during gestation. PL-I mRNA expression was assessed by in situ hybridization, and expression of PL-I and PL-II protein was determined by immunocytochemical analysis. PL-I mRNA and protein were localized to trophoblast giant cells. Trophoblast giant cells ceased producing PL-I at midgestation and began expressing PL-II. PL-I immunoreactivity was present in trophoblast giant cells on Days 9 and 10 of gestation but was not detectable in trophoblast giant cells on Day 11 of gestation. Immunoreactive PL-II-producing giant cells were detected first on Day 10 of gestation, continuing on Day 11 of gestation. Expression of PL-I and PL-II signals a significant functional transition in trophoblast giant cells of the developing mouse placenta.     

Changes in cytosolic and nuclear progesterone receptors during pregnancy in rat placenta

These studies examine changes in placental growth and the abundance of progesterone receptors (Rp) in whole placentas between Days 9 and 22 of pregnancy. In addition, some placentas were dissected into decidual basalis, junctional zone, and labyrinth zone before assay of Rp. High affinity binding of 3H-progesterone to Rp was detected at all stages of pregnancy in whole placentas and in decidua basalis and the junctional zone of the placenta. Cytosolic and nuclear receptors exhibited similar affinity for progesterone in both tissues (Kd = 3.1 +/- 0.3 and 4.4 +/- 0.7 nM, respectively). Receptor binding in whole placentas increased from Day 9 to Day 12 (p less than 0.05), declined markedly at Day 16 (p less than 0.05), and returned to former levels on Days 19 and 22 (p less than 0.05). Decidua basalis contained 84% of total Rp on Day 14, which declined to 67% on Day 17 (p less than 0.05). The junctional zone contained 16% of total Rp on Day 14 and 33% on Day 17. After Day 17, junctional zone was the only source of Rp. The decline in Rp on Day 16 followed regression of decidua basalis; recovery of Rp thereafter was due to growth of the junctional zone. The labyrinth zone did not express significant amounts of Rp at any stage despite a 4-fold increase in growth in late pregnancy. Although the biologic role of the Rp in maintenance of pregnancy is poorly understood, these studies suggest that the maternal decidua basalis and fetal junctional zone are targets of progesterone action.     

A route from d-galactose to the aggregation pheromone component (-)-α-multistriatin

Oxidation of 3,6-di-O-benzyl-1,2-O-isopropylidene-α-d-glucofuranose with pyridinium chlorochromate in the presence of molecular sieves, followed by conversion into the p-tolylsulfonylhydrazone, addition of methyl phenylphosphinate, and reduction with sodium borohydride, provided the key intermediate, namely, 5(R,S)-3,6-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-5-C-[(methoxy)phenylphosphinyl]-α-d-xylo-hexofuranose, in 23% overall yield. Treatment of this compound with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by the action of mineral acid and acetic anhydride, yielded the crystalline title compound, the structure of which was established on the basis of mass and 400-MHz, ¹H-n.m.r. spectra. A general dependence of ²J_PH values on the OPCH dihedral angles effectively served for assigning the configuration of C-1, C-5, and the ring-phosphorus atom of the present product and other such 5-C-phosphinylhexopyranoses.