Giant lungfish genome elucidates the conquest of land by vertebrates

Lungfishes belong to lobe-fined fish (Sarcopterygii) that, in the Devonian period, ‘conquered’ the land and ultimately gave rise to all land vertebrates, including humans1–3. Here we determine the chromosome-quality genome of the Australian lungfish (Neoceratodus forsteri), which is known to have the largest genome of any animal. The vast size of this genome, which is about 14× larger than that of humans, is attributable mostly to huge intergenic regions and introns with high repeat content (around 90%), the components of which resemble those of tetrapods (comprising mainly long interspersed nuclear elements) more than they do those of ray-finned fish. The lungfish genome continues to expand independently (its transposable elements are still active), through mechanisms different to those of the enormous genomes of salamanders. The 17 fully assembled lungfish macrochromosomes maintain synteny to other vertebrate chromosomes, and all microchromosomes maintain conserved ancient homology with the ancestral vertebrate karyotype. Our phylogenomic analyses confirm previous reports that lungfish occupy a key evolutionary position as the closest living relatives to tetrapods4,5, underscoring the importance of lungfish for understanding innovations associated with terrestrialization. Lungfish preadaptations to living on land include the gain of limb-like expression in developmental genes such as hoxc13 and sall1 in their lobed fins. Increased rates of evolution and the duplication of genes associated with obligate air-breathing, such as lung surfactants and the expansion of odorant receptor gene families (which encode proteins involved in detecting airborne odours), contribute to the tetrapod-like biology of lungfishes. These findings advance our understanding of this major transition during vertebrate evolution.

CHEMICAL COMPOSITION OF TUALANG HONEY AND ITS EFFECT ON THE LUNG SURFACTANTS AND HISTOLOGY OF MALE RATS EXPOSED TO CIGARETTE SMOKE

This study reported the chemical composition of Tualang honey and its effect on the lung surfactants and histology of male rats exposed to cigarette smoke. Thirty-two adult male Sprague-Dawley rats were used and they were randomly divided into 4 groups of eight rats each: control, honey-treated (Honey), cigarette smoke-exposed (CS) and honey-treated plus CS (Honey+CS). Rats in control and CS groups received distilled water (0.5 mL/day) while rats in Honey and Honey+CS groups received honey (1.2 g/kg body weight/day) by oral gavage. Furthermore, rats in CS and Honey+CS groups were exposed to CS in a chamber for 8 minutes (3 times/day). Exposure of rats to cigarette smoke significantly altered their phosphatidyl choline/ phosphatidyl glycerol (PC/PG) ratio but not their surfactant protein A levels with increased number of alveolar macrophage containing carbon particles. Administration of Tualang honey to CS exposed rats resulted in modulation of most of these parameters and which results were coroborrated by histology. The colour intenstity, pH and moisture content of the honey were obtained as 272.75 mili-absorbance unit, 3.43 and 17.38%, respectively. Screening for phenolic compounds in Tualang honey using High Performance Thin Layer Chromatography showed the presence of 18 compounds while only five were identified which possessed strong in vitro antioxidant capacity as seen from their 2,2,diphenyl-1-picryl hydrazyl radical scavenging ability. The study showed the promising potentials of Tualung honey in protecting lung surfactants from the deleterious action of cigarette smoke which may be associated with its antioxidant phenolic compounds.Key words: tualang honey; surfactant; inhalation toxicology; phenolic compounds KEMIČNA SESTAVA MEDU TUALANG IN NJEGOV VPLIV NA POVRŠINSKO AKTIVNE SNOVI V PLJUČIH TER HISTOLOGIJO PLJUČ SAMCEV PODGAN, IZPOSTAVLJENIH CIGARETNEM DIMUPovzetek: Raziskava poroča o kemijski sestavi medu Tualang in njegovem vplivu na površinsko aktivne snovi v pljučih ter histologijo pljuč samcev podgan, izpostavljenih cigaretnemu dimu. V študiji so uporabili 32 odraslih podgajih samcev seva Sprague-Dawley, ki so bili naključno razdeljeni v 4 skupine po osem podgan: kontrolna skupina, skupina, ki je uživala med s prehrano (Honey), skupina, ki je bila izpostavljena cigaretnemu dimu (CS) in skupina, ki je bila izpostavljena cigaretnemu dimu ter je uživala med (Honey+CS). Podgane v kontrolnih skupinah in skupinah CS so dobile destilirano vodo (0,5 ml/dan), podgane v skupinah Honey in Honey + CS pa peroralno med (1,2 g/kg telesne teže/dan). Poleg tega so bile podgane v skupinah CS in Honey + CS izpostavljene v komori cigaretnemu dimu trikrat na dan po 8 minut. Izpostavljenost podgan cigaretnemu dimu je bistveno spremenila razmerje fosfatidilholina/fosfatidilglicerola (PC/PG), ne pa tudi ravni površinsko aktivne snovi A v pljučih in ni vplivala na število alveolarnih makrofagov, ki vsebujejo ogljikove delce. Uporaba medu Tualang pri podganah, izpostavljenih cigaretnemu dimu, je povzročila spremembo večine opazovanih parametrov, katerih rezultati so bili potrjeni s histološko preiskavo. Intenzivnost barve medu je bila 272,75 enote mili-absorbance, pH 3,43, vsebnost vlage v medu pa je bila 17,38 %. Presejalni test na fenolne spojin v medu Tualang s tankoplastno kromatografijo je pokazal prisotnost 18 spojin, od katerih jih je bilo 5 prepoznanih kot spojine z močno in vitro antioksidativno sposobnostjo, kot je razvidno iz njihove sposobnosti odstranjevanja radikala 2,2-difenil-1-pikril hidrazila. Študija je pokazala obetavne potenciale medu Tualung pri zaščiti pljučnih površinsko aktivnih snovi pred škodljivim delovanjem cigaretnega dima, kar je lahko povezano z njegovimi antioksidativnimi fenolnimi spojinami.Kjučne besede: med tualang; surfaktant; inhalacijska toksikologija; fenoli

Drug design of anti-covid19 agents

The first step to drug development that precedes formulation is drug design. In this commentary the specific design of antiviral agents for Covid19 and future viruses, which can be achieved with different strategies, is highlighted. An extended release type of formulation would be ideal for site-specific antivirals however early in vitro or toxicology screening is very important. A lot of preparations are already available to be exploited. Conversely, some are available for pediatric use, i.e lung surfactants, which understandably the supply of is aimed at premature children. New lung surfactant design for adults could however be also incentivised which may help re-establishing autonomous respiration (autonomically mediated) post-covid19 infection of the individual. The surfactants could also help counteract dyspnea which is sometimes a known side effect of antiviral agents.

Micro-Surface and -Interfacial Tensions Measured Using the Micropipette Technique: Applications in Ultrasound-Microbubbles, Oil-Recovery, Lung-Surfactants, Nanoprecipitation, and Microfluidics

This review presents a series of measurements of the surface and interfacial tensions we have been able to make using the micropipette technique. These include: equilibrium tensions at the air-water surface and oil-water interface, as well as equilibrium and dynamic adsorption of water-soluble surfactants and water-insoluble and lipids. At its essence, the micropipette technique is one of capillary-action, glass-wetting, and applied pressure. A micropipette, as a parallel or tapered shaft, is mounted horizontally in a microchamber and viewed in an inverted microscope. When filled with air or oil, and inserted into an aqueous-filled chamber, the position of the surface or interface meniscus is controlled by applied micropipette pressure. The position and hence radius of curvature of the meniscus can be moved in a controlled fashion from dimensions associated with the capillary tip (~5–10 μm), to back down the micropipette that can taper out to 450 μm. All measurements are therefore actually made at the microscale. Following the Young–Laplace equation and geometry of the capillary, the surface or interfacial tension value is simply obtained from the radius of the meniscus in the tapered pipette and the applied pressure to keep it there. Motivated by Franklin’s early experiments that demonstrated molecularity and monolayer formation, we also give a brief potted-historical perspective that includes fundamental surfactancy driven by margarine, the first use of a micropipette to circuitously measure bilayer membrane tensions and free energies of formation, and its basis for revolutionising the study and applications of membrane ion-channels in Droplet Interface Bilayers. Finally, we give five examples of where our measurements have had an impact on applications in micro-surfaces and microfluidics, including gas microbubbles for ultrasound contrast; interfacial tensions for micro-oil droplets in oil recovery; surface tensions and tensions-in-the surface for natural and synthetic lung surfactants; interfacial tension in nanoprecipitation; and micro-surface tensions in microfluidics.

Interfacial curvature effects on the monolayer morphology and dynamics of a clinical lung surfactant

The morphology of surfactant monolayers is typically studied on the planar surface of a Langmuir trough, even though most physiological interfaces are curved at the micrometer scale. Here, we show that, as the radius of a clinical lung surfactant monolayer-covered bubble decreases to ∼100 µm, the monolayer morphology changes from dispersed circular liquid-condensed (LC) domains in a continuous liquid-expanded (LE) matrix to a continuous LC linear mesh separating discontinuous LE domains. The curvature-associated morphological transition cannot be readily explained by current liquid crystal theories based on isotropic domains. It is likely due to the anisotropic bending energy of the LC phase of the saturated phospholipids that are common to all natural and clinical lung surfactants. This continuous LC linear mesh morphology is also present on bilayer vesicles in solution. Surfactant adsorption and the dilatational modulus are also strongly influenced by the changes in morphology induced by interfacial curvature. The changes in morphology and dynamics may have physiological consequences for lung stability and function as the morphological transition occurs at alveolar dimensions.