A biomechanical analysis of prognathous and orthognathous insect head capsules: evidence for a many‐to‐one mapping of form to function

Insect head shapes are remarkably variable, but the influences of these changes on biomechanical performance are unclear. Among ‘basal’ winged insects, such as dragonflies, mayflies, earwigs and stoneflies, some of the most prominent anatomical changes are the general mouthpart orientation, eye size and the connection of the endoskeleton to the head. Here, we assess these variations as well as differing ridge and sclerite configurations using modern engineering methods including multibody dynamics modelling and finite element analysis in order to quantify and compare the influence of anatomical changes on strain in particular head regions and the whole head. We show that a range of peculiar structures such as the genal/subgenal, epistomal and circumocular areas are consistently highly loaded in all species, despite drastically differing morphologies in species with forward‐projecting (prognathous) and downward‐projecting (orthognathous) mouthparts. Sensitivity analyses show that the presence of eyes has a negligible influence on head capsule strain if a circumocular ridge is present. In contrast, the connection of the dorsal endoskeletal arms to the head capsule especially affects overall head loading in species with downward‐projecting mouthparts. Analysis of the relative strains between species for each head region reveals that concerted changes in head substructures such as the subgenal area, the endoskeleton and the epistomal area lead to a consistent relative loading for the whole head capsule and vulnerable structures such as the eyes. It appears that biting‐chewing loads are managed by a system of strengthening ridges on the head capsule irrespective of the general mouthpart and head orientation. Concerted changes in ridge and endoskeleton configuration might allow for more radical anatomical changes such as the general mouthpart orientation, which could be an explanation for the variability of this trait among insects. In an evolutionary context, many‐to‐one mapping of strain patterns onto a relatively similar overall head loading indeed could have fostered the dynamic diversification processes seen in insects.     

Mixture design of starchy substrates hydrolysis by an immobilized glucoamylase from Aspergillus brasiliensis

Starch has great importance in human diet, since it is a heteropolymer of plants, mainly found in roots, as potato, cassava and arrowroots. This carbohydrate is composed by a highly-branched chain: amylopectin; and a linear chain: amylose. The proportion between the chains varies according to the botanical source. Starch hydrolysis is catalyzed by enzymes of the amilolytic system, named amylases. Among the various enzymes of this system, the glucoamylases (EC 3.2.1.3 glucan 1,4-alpha-glucosidases) are the majority because they hydrolyze the glycosidic linkages at the end of starch chains releasing glucose monomers. In this work, a glucoamylase secreted in the culture medium, by the ascomycete Aspergillus brasiliensis, was immobilized in Dietilaminoetil Sepharose-Polyethylene Glycol (DEAE-PEG), since immobilized biocatalysts are more stable in long periods of hydrolysis, and can be recovered from the final product and reused for several cycles. Glucoamylase immobilization has shown great thermal stability improvement over the soluble enzyme, reaching 66% more activity after 6?h at 60?°C, and 68% of the activity after 10 hydrolysis cycles. A simplex centroid experimental mixture design was applied as a tool to characterize the affinity of the immobilized enzyme for different starchy substrates. In assays containing several proportions of amylose, amylopectin and starch, the glucoamylase from A. brasiliensis mainly hydrolyzed the amylopectin chains, showing to have preference by branched substrates.     

Synchronous bilateral breast cancer patients submitted to conservative treatment and brachytherapy – The experience of a service

Introduction

The incidence of breast carcinoma (BC) has increased in the last years. Between 2 and 12% of patients diagnosed with BC will develop bilateral breast carcinoma (BBC). The treatment of these carcinomas is more aggressive than unilateral BC.

Stability of aerobic granules during long-term bioreactor operation

Aerobic granular sludge technology has been extensively studied over the past 20 years and is regarded as the upcoming new standard for biological treatment of domestic and industrial wastewaters. Aerobic granules (AG) are dense, compact, self-immobilized microbial aggregates that allow better sludge-water separation and thereby higher biomass concentrations in the bioreactor than conventional activated sludge aggregates. This brings potential practical advantages in terms of investment cost, energy consumption and footprint. Yet, despite the relevant advances regarding the process of AG formation, instability of AG during long-term operation is still seen as a major barrier for a broad practical application of this technology. This paper presents an up-to-date review of the literature focusing on AG stability, aiming to contribute to the identification of key factors for promoting long-term stability of AG and to a better understanding of the underlying mechanisms. Operational conditions leading to AG disintegration are described, including high organic loads, particulate substrates in the influent, toxic feed components, aerobic feeding and too short famine periods. These operational and influent wastewater composition conditions were shown to influence the micro-environment of AG, consequently affecting their stability. Granule stability is generally favored by the presence of a dense core, with microbial growth throughout the AG depth being a crucial intrinsic factor determining its structural integrity. Accordingly, possible practical solutions to improve granule long-term stability are described, namely through the promotion of minimal substrate concentration gradients and control of microbial growth rates within AG, including anaerobic, plug-flow feeding and specific sludge removal strategies.     

Plasmodium falciparum invasion and intraerythrocytic development are impaired by 2′, 3′-dialdehyde adenosine

Purine nucleotide synthesis in protozoa takes place exclusively via the purine salvage pathway and S-adenosyl-l-homocysteine hydrolase (SAHH) is an important enzyme in the Plasmodium salvage pathway which is not present in erythrocytes. Here, we describe the antimalarial effect of 2′3′-dialdehyde adenosine or oxidized adenosine (oADO), inhibitor of SAHH, on in vitro infection of human erythrocytes by P. falciparum. Treatment of infected erythrocytes with oADO inhibits parasite development and reinvasion of new cells. Erythrocytes pre-treated with oADO have a reduced susceptibility to invasion. Our results suggest that oADO interferes with one or more parasitic enzymes of the purine salvage pathway.     

Brassinosteroid increases the cytokinin efficiency to induce direct somatic embryogenesis in leaf explants of <Emphasis Type="Italic">Coffea arabica</Emphasis> L. (Rubiaceae)

The combination of different plant growth regulators can result in beneficial effects in the induction of in vitro morphogenetic pathways. The present study reports the effect of 24-epibrassinolid (24-epiBR; brassinosteroid) when added alone and in association with N⁶-(2-isopentnyl) adenine (2-iP; cytokinin) in the induction of direct somatic embryogenesis in Coffea arabica. Leaf explants were cultivated in a modified Murashige and Skoog (MS) medium with 0 or 10 µM 2-iP and different concentrations (0.01, 0.10 or 1.0 µM) of 24-epiBR. Explants cultured on MS medium supplemented with 1.0 µM 24-epiBR in association with 2-iP produced 6.8 times more somatic embryos than the explants cultured with only 2-iP. Histological analyses also provided evidence that the supplementation of brassinosteroids in the culture medium could have influenced somatic embryogenesis differentiation. Somatic embryos obtained in the presence of brassinosteroid and cytokinin were better structured morpho-histologically as compared to those obtained in the medium with just cytokinin. This study opens new perspectives for the use of brassinosteroids in the somatic embryogenesis of C. arabica, so as to optimize the in vitro regeneration systems used in genetic improvement programs in C. arabica productive systems.     

Reproduction in Bagre marinus (Ariidae) off Pernambuco, northeastern Brazil

Throughout 1997, the catches of artisanal gillnetters working off the coast of northeastern Brazil were sampled monthly for Bagre marinus (Mitchill 1815). Significantly more females (n = 207) than males (n = 82) were caught, although there was no significant difference in their size compositions (21–47 cm fork length, FL). All males sampled (21–40 cm FL) had developed gonads and were classified as sexually mature. According to macroscopic and microscopic examination of their reproductive tract, females were separated into four reproductive stages (immature, maturing, mature, and resting). Size at 50% sexual maturity for females was estimated to be 33 cm FL. A positive linear relationship was detected between the size of mature females and their fecundity (between 11 and 32 oocytes). Clear reproductive progress indicated a spawning period between March and May. We conclude that further fishery‐independent data are required to determine patterns of male abundances and distributions.     

Upper and lower mesophotic coral reef fish communities evaluated by underwater visual censuses in two Caribbean locations

Despite more than 60 yr of coral reef research using scuba diving, mesophotic coral ecosystems (MCEs) between 30 and 150 m depth remain largely unknown. This study represents the first underwater visual census of reef fish communities in the Greater Caribbean on MCEs at depths up to 80 m in Bermuda and 130 m in Curaçao. Sampling was performed using mixed-gas closed-circuit rebreathers. Quantitative data on reef fish communities were obtained for four habitats: coral reefs (45–80 m), rhodolith beds (45–80 m), ledges (85–130 m) and walls (85–130 m). A total of 38 species were recorded in Bermuda and 66 in Curaçao. Mesophotic reef fish communities varied significantly between the two localities. MCEs in Bermuda had lower richness and abundance, but higher biomass than those in Curaçao. Richness, abundance and biomass increased with depth in Bermuda, but decreased in Curaçao. A high turnover of species was found among depth strata and between Bermuda and other Caribbean upper MCEs (45–80 m), indicating that depth was an important driver of community structure at all localities. However, local and evolutionary factors (habitat and endemism) are likely the main factors shaping communities in isolated locations such as Bermuda. High fishing pressure is evident in both localities, as total biomass of apex predators was generally low, and thus may be driving a “refugia” scenario in Bermuda, as the abundance and biomass of macro-carnivores increased with depth and distance from the coast.