Rejoinder to Discussions on “Approval policies for modifications to machine learning‐based software as a medical device: A study of bio‐creep”

We thank the discussants for sharing their unique perspectives on the problem of designing automatic algorithm change protocols (aACPs) for machine learning‐based software as a medical device. Both Pennello et al. and Rose highlighted a number of challenges that arise in real‐world settings, and we whole‐heartedly agree that substantial extensions of our work are needed to understand if and how aACPs can be safely deployed in practice. Our work demonstrated that aACPs that appear to be harmless may allow for biocreep, even when the data distribution is assumed to be representative and stationary over time. While we investigated two solutions that protect against this specific issue, many more statistical and practical challenges remain and we look forward to future research on this topic.     

Diet and trophic position of two mackerel species in the archipelago of Madeira,Portugal

The Atlantic chub mackerel Scomber colias and the blue jack mackerel Trachurus picturatus are two abundant species in the Macaronesia region which includes the archipelago of Madeira, Portugal. Both are key species in the trophic web, being important prey for several local top predators, such as seabirds and marine mammals. Nonetheless, little is known about their feeding ecology in oceanic environments. In this study, the authors describe the seasonal variation in the diet of S. colias and T. picturatus in the oceanic region of Madeira throughout a year. Visual inspection of stomach contents revealed that S. colias fed on a broader range of prey groups than T. picturatus, but for both species, zooplankton (particularly calanoid copepods) and fish were the most important food items. The diet of S. colias included a higher proportion of fish, namely Atlantic saury Scomberesox saurus and S. colias, than that of T. picturatus, that included mostly the longspine snipefish Macroramphosus scolopax. T. picturatus consumed a higher proportion of decapods and other copepods. Seasonal variation was found in the diet of both species, with zooplanktonic species being more important in colder months (February to April) for S. colias and during warm months (May to October) for T. picturatus. Their diet in other seasons was dominated by fish. Although they consume similar prey, carbon and nitrogen stable isotope analysis of muscle of S. colias and T. picturatus showed little overlap in their diets, and T. picturatus showed higher δ¹⁵N and a narrower isotopic niche.     

Screening the dermatological potential of Plectranthus species components: antioxidant and inhibitory capacities over elastase,collagenase and tyrosinase

A series of Plectranthus spp. plant extracts (aqueous, acetonic, methanolic and ethyl acetic) obtained from eight different species, and previously isolated compounds (ranging from polyphenols, diterpenes and triterpenes), were assayed for in vitro inhibition of the skin-related enzymes tyrosinase, collagenase and elastase, and for studying their antioxidant properties. The ethyl acetic extracts of P. grandidentatus and P. ecklonii registered the highest antioxidant activity, whereas acetonic, methanolic and ethyl acetic extracts of P. ecklonii, P. grandidentatus, P. madagascariensis and P. saccatus concerning the enzymatic inhibition assays revealed high anti-tyrosinase and anti-collagenase activities. From the isolated compounds tested, abietane diterpenes and triterpenes were highly active against tyrosinase and elastase activity. Overall, the experimental results showed the powerful antioxidant and inhibitory action on skin-related enzymes tyrosinase, collagenase and elastase of Plectranthus spp. extracts and/or isolated compounds, supporting their further research as bioactive metabolites against skin sagging and hyperpigmentation in cosmetic and pharmaceutical formulations.     

Trypanocidal Activity of Dysphania ambrosioides,Lippia alba,and Tetradenia riparia Essential Oils against Trypanosoma cruzi

Despite the current treatments against Chagas Disease (CD), this vector-borne parasitic disease remains a serious public health concern. In this study, we have explored the in vitro and/or in vivo trypanocidal and cytotoxic activities of the essential oils (EOs) obtained from Dysphania ambrosioides (L.) Mosyakin & Clemants (Amaranthaceae) (DA-EO), Lippia alba (Mill.) N.E. Brown (Verbenaceae) (LA-EO), and Tetradenia riparia (Hochst.) Codd (Lamiaceae) (TR-EO) grown in Brazil Southeast. DA-EO was the most active against the trypomastigote and amastigote forms in vitro; the IC₅₀ values were 8.7 and 12.2 μg mL⁻¹, respectively. The EOs displayed moderate toxicity against LLCMK2 cells, but the DA-EO showed high selectivity index (SI) for trypomastigote (SI=33.2) and amastigote (SI=11.7) forms. Treatment with 20 mg/kg DA-EO, LA-EO, or TR-EO for 20 days by intraperitoneal administration reduced parasitemia by 6.36 %, 4.74 %, and 32.68 % on day 7 and by 12.04 %, 27.96 %, and 65.5 % on day 9. These results indicated that DA-EO, LA-EO, and TR-EO have promising trypanocidal potential in vitro, whereas TR-EO has also potential trypanocidal effects in vivo.     

Computer-Guided Trypanocidal Activity of Natural Lactones Produced by Endophytic Fungus of Euphorbia umbellata

Hundreds of millions of people worldwide are affected by Chagas’ disease caused by Trypanosoma cruzi. Since the current treatment lack efficacy, specificity, and suffers from several side-effects, novel therapeutics are mandatory. Natural products from endophytic fungi have been useful sources of lead compounds. In this study, three lactones isolated from an endophytic strain culture were in silico evaluated for rational guidance of their bioassay screening. All lactones displayed in vitro activity against T. cruzi epimastigote and trypomastigote forms. Notably, the IC₅₀ values of (+)-phomolactone were lower than benznidazole (0.86 vs. 30.78 μM against epimastigotes and 0.41 vs. 4.88 μM against trypomastigotes). Target-based studies suggested that lactones displayed their trypanocidal activities due to T. cruzi glyceraldehyde-3-phosphate dehydrogenase (TcGAPDH) inhibition, and the binding free energy for all three TcGAPDH-lactone complexes suggested that (+)-phomolactone has a lower score value (−3.38), corroborating with IC₅₀ assays. These results highlight the potential of these lactones for further anti-T. cruzi drug development.     

Modulation of physiological performance by temperature and salinity in the sugar kelp Saccharina latissima

The sugar kelp Saccharina latissima experiences a wide range of environmental conditions along its geographical and vertical distribution range. Temperature and salinity are two critical drivers influencing growth, photosynthesis and biochemical composition. Moreover, interactive effects might modify the results described for single effects. In shallow water coastal systems, exposure to rising temperatures and low salinity are expected as consequence of global warming, increased precipitation and coastal run‐off. To understand the acclimation mechanisms of S. latissima to changes in temperature and salinity and their interactions, we performed a mechanistic laboratory experiment in which juvenile sporophytes from Brittany, France were exposed to a combination of three temperatures (0, 8 and 15°C) and two salinity levels (20 and 30 psu (practical salinity units)). After a temperature acclimation of 7 days, sporophytes were exposed to low salinity (20 psu) for a period of 11 days. Growth, and maximal quantum yield of photosystem II (Fv/Fm), pigments, mannitol content and C:N ratio were measured over time. We report for the first time in S. latissima a fivefold increase in the osmolyte mannitol in response to low temperature (0°C) compared to 8 and 15°C that may have ecological and economic implications. Low temperatures significantly affected all parameters, mostly in a negative way. Chlorophyll a, the accessory pigment pool, growth and Fv/Fm were significantly lower at 0°C, while the de‐epoxidation state of the xanthophyll cycle was increased at both 0 and 8°C compared to 15°C. Mannitol content and growth decreased with decreased salinity; in contrast, pigment content and Fv/Fm were to a large extent irresponsive to salinity. In comparison to S. latissima originating from an Arctic population, despite some reported differences, this study reveals a remarkably similar impact of temperature and salinity variation, reflecting the large degree of adaptability in this species.     

Toxicity of rhizomes of the invasive Hedychium coronarium (Zingiberaceae) on aquatic species

The production and release of chemical compounds by invasive plants can affect competitors and native species overall, destabilizing ecological interactions and harming ecosystem functioning. Hedychium coronarium is an invasive macrophyte common on Brazilian riparian areas that produces a wide variety of allelochemicals, but little is known about their effect on aquatic species. Here, we identified the major chemical compounds of the aqueous extract of H. coronarium rhizomes and assessed its toxicity, evaluating the growth inhibition of one alga (Raphidocelis subcapitata) and one macrophyte (Lemna minor), and the lethality of cladoceran (Ceriodaphnia silvestrii and Daphnia similis) and Chironomidae larvae (Chironomus sancticaroli). The majoritarian compounds of H. coronarium rhizomes were Coronarin D and Coronarin D Ethyl Ether. The aqueous extract was toxic for all tested species. We observed growth inhibition in R. subcapitata, as well as reduction in biomass in L. minor. Chironomus sancticaroli and cladoceran were the most sensible species. The aqueous extract of H. coronarium rhizomes was toxic on tested conditions, suggesting that the rhizome compounds may interfere on aquatic organisms and in the dynamic of trophic webs of aquatic ecosystems on invaded areas.

     

Molecular underpinnings of the early brain developmental response to differential feeding in the honey bee Apis mellifera

Brain differential morphogenesis in females is one of the major phenotypic manifestations of caste development in honey bees. Brain diphenism appears at the fourth larval phase as a result of the differential feeding regime developing females are submitted during early phases of larval development. Here, we used a forward genetics approach to test the early brain molecular response to differential feeding leading to the brain diphenism observed at later developmental phases. Using RNA sequencing analysis, we identified 53 differentially expressed genes (DEGs) between the brains of queens and workers at the third larval phase. Since miRNAs have been suggested to play a role in caste differentiation after horizontal and vertical transmission, we tested their potential participation in regulating the DEGs. The miRNA-mRNA interaction network, including the DEGs and the royal- and worker-jelly enriched miRNA populations, revealed a subset of miRNAs potentially involved in regulating the expression of DEGs. The interaction of miR-34, miR-210, and miR-317 with Takeout, Neurotrophin-1, Forked, and Masquerade genes was experimentally confirmed using a luciferase reporter system. Taken together, our results reconstruct the regulatory network that governs the development of the early brain diphenism in honey bees.     

In vitro propagation, histochemistry, and analysis of essential oil from conventionally propagated and in vitro-propagated plants of Varronia curassavica Jacq

Varronia curassavica is cultivated for the production of an essential oil useful in the pharmaceutical industry for its strong anti-inflammatory effect. Despite a growing demand, only a few studies have evaluated alternative sources of obtaining plantlets or ways to increase the yield of essential oil from this species. Therefore, this study aimed to optimize the in vitro multiplication rate and analyze the histochemistry and sesquiterpene production potential of conventionally propagated V. curassavica plants, in vitro shoots, and acclimatized plants derived from in vitro shoots. For axillary bud proliferation, Murashige and Skoog medium was supplemented with 6-benzyladenine and thidiazuron alone or in combination with naphthalene acetic acid. Axillary bud proliferation was obtained from culture of nodal or apical segments on medium containing half-strength Murashige and Skoog salts without growth regulators. After 35 d of culture, an average of five buds developed per explant. Elongation and rooting of shoots also occurred in this medium. After the transfer of rooted plants to ex vitro conditions, 100% of the plantlets survived. Histochemical analysis of leaf tissue showed the presence of lipids, acidic lipids, essential oil, phenols, and flavonoids. The essential oils from conventionally propagated and acclimatized plants were extracted by hydrodistillation and analyzed using gas chromatography. The essential oil from acclimatized plants had a similar profile to that from ex vitro plants, but with a higher concentration of the anti-inflammatory compound alpha-humulene.