Shell Morphology Research Articles

Separation of Nanoparticle Seed Pseudoisomers via Amplification of Their Crystallographic Differences.

Seed-mediated syntheses rely on small nanoparticle (NP) precursors that act as templates for growth but are often inhomogeneous with respect to their internal twinning structures (e.g., single crystalline, multiply twinned), leading to nonuniform product morphologies. To address this, we developed a method for separating seed NPs of the same approximate size (∼ 10 nm) but with different interior twinning (i.e., NP "pseudoisomers") by exaggerating their crystallographic differences through heteroexpitaxial metal overgrowth. Specifically, single crystalline and pentatwinned Au seeds that are natively inseparable via traditional methods exhibit drastically different Ag shell morphologies that allow for their selective precipitation through colloidal depletion forces. Oxidation of the Ag shell from separated particles results in seeds that are both size uniform and crystallographically pure (>99%), allowing for the controlled synthesis of a library of Oh- and D5h-symmetric gold NPs bearing {111}, {110}, {730}, {310}, {720}, and {100} facets, several of which have no precedent in the literature. These results lay the foundation for precision nanosynthesis by establishing a new paradigm for the purification of NP precursors.

Morphometric differentiation of Landouria smimensis along altitudinal gradient

Landouria smimensis is an endemic land snail found in the Mount Semeru area. This species can be found in different altitudes of Mount Semeru. The study aimed to analyze the morphometric of L. smimensis shells along the altitudinal gradient of Mount Semeru. Samples were taken from four altitudinal gradients of Mount Semeru from October 2021 to June 2022. In total, 114 individuals of L. smimensis were measured based on shell morphology characters. The characters were the height and diameter of the shell, the height and diameter of the aperture, the diameter of the first three whorl, and the number of whorls. Shell morphometric was measured using ImageJ and analyzed using PAST. Most shell morphology characters showed the differentiation among the altitudinal gradient (p<0.05), except between 1601-2000 m asl and 2001-2400 m asl (p>0.05). The shell morphology characters from the population below 1200 m asl are significantly the biggest than population from others altitudes. Most shell morphology characters negatively correlated with the altitude. It is known that the shell morphometric characters of the shells can be a differentiates among populations of L. smimensis at each altitude.

Unusual Shell Morphologies of Responsive Amino Core‐Shell Microgels Induced by pH During Shell Synthesis

AbstractThe properties of pH‐responsive microgels are strongly influenced by the pH value during synthesis. In this work, based on a N‐n‐propylacrylamide (NNPAM) core with N‐3‐(dimethylamino)propylmethacrylamide (DAPMA) as a comonomer, a series of core‐shell microgels with shells from NNPAM and N‐(3‐aminopropyl)methacrylamide hydrochloride (APMH) are synthesized at different pH values. While the swelling behavior is studied with temperature‐ and angle‐dependent photon correlation spectroscopy (PCS), the size and morphology are also investigated by means of atomic force microscopy (AFM) and static light scattering (SLS). At acidic pH, rather monodisperse microgels with a very fuzzy shell are obtained. The microgels evolve particulate structures on their shell at intermediate pH until not only a core‐shell microgel but also a secondary microgel species is produced at basic pH. By altering the synthesis pH, it is possible to influence the morphology of core‐shell microgels to suit future applications like the uptake and release of drugs or surface modification.

Metabolic scaling variation as a constitutive adaptation to tide level in Mytilus galloprovincialis

Understanding how allometric exponents vary in the different biologically determined patterns turns out to be fundamental for the development of a unifying hypothesis that intends to explain most of the variation among taxa and physiological states. The aims of this study were (i) to analyze the scaling exponents of oxygen consumption at different metabolic rates in Mytilus galloprovincialis according to different seasons, habitat, and acclimation to laboratory conditions and (ii) to examine the variation in shell morphology depending on habitat or seasonal environmental hazards. The allometric exponent for standard metabolic rate (b value) did not vary across seasons or tide level, presenting a consistent value of 0.644. However, the mass-specific standard oxygen consumption (a value), i.e. metabolic level, was lower in intertidal mussels (subtidal mussels: a = - 1.364; intertidal mussels: a = - 1.634). The allometric exponent for routine metabolic rate changed significantly with tide level: lower allometric exponents for intertidal mussels (b = 0.673) than for subtidal mussels (b = 0.871). This differential response did not change for at least two months after the environmental cue was removed. We suggest that this is the result of intertidal mussels investing fundamentally in surface-dependent organs (gill and shell), with the exception of the slightly higher values obtained in May as a likely consequence of gonadal tissue development. Subtidal mussels, on the contrary, are probably in constant demand for volume-related resources, which makes them consistently obtain an allometric exponent of around 0.87.

Description of the early shell morphology of three species of Pectinidae (Mollusca: Bivalvia) from Argentina.

We describe the shell morphology of the prodissoconch and early postlarval shell of Aequipecten tehuelchus (dOrbigny), Flexopecten felipponei (Dall), and Zygochlamys patagonica (King) from the southern coast of Argentina. Aequipecten tehuelchus has a nepioconch microsculpture with fine, dense, and regularly distributed pits. The byssal notch is initially deep and narrow but becomes sinuous at the beginning of the post-nepioconch. The nepioconch of Zygochlamys patagonica has antimarginal riblets; the byssal notch is wider than in A. tehuelchus and does not present the sinuosity observed in the other species. The microsculpture of the nepioconchs of F. felipponei and A. tehuelchus is indistinguishable. The earliest differentiation between the two species appears with the post-nepionic left valve, in which A. tehuelchus exhibits between 15 and 20 primary ribs while F. felipponei displays 28 to 34 faint folds. Zygochlamys patagonica shows 21 to 31 primary and secondary ribs. The taxonomic status of the three species is discussed in light of these findings and with respect to current adult-shell taxonomy and genetic analyses.

Mineralization of Shells of Emulsion Polyelectrolyte Microcapsules by Calcium Carbonate

The calcium-carbonate-induced mineralization of multilayer shells of emulsion capsules, formed using layer-by-layer assembly of polyelectrolytes, has been investigated. Optimal conditions for forming microcapsules with a core from shea butter and an organic–inorganic shell from synthetic polyelectrolytes and calcium carbonate are found. The shell morphology and stability of capsules in an aqueous suspension upon heating are investigated, and their cytotoxicity for human fibroblast cells is estimated. It is shown that mineralization of emulsion polyelectrolyte capsules by calcium carbonate in the form of vaterite strengthens the capsule walls and increases their biocompatibility.

An overview of the specific diversity in the genus Cystiscus Stimpson, 1865 and the description of 27 new Cystiscus species (Muricoidea: Cystiscidae) from the Walters Shoal, southwestern Indian Ocean

The Cystiscus fauna collected on the Walters Shoal by the 2017 MNHN/IRD Expedition is revised on the ground of shell morphology. Twenty-nine different species are recognized, 27 of them being formally described as Cystiscus subcylindricus, sp. nov., C. triplicatus sp. nov., C. herberti sp. nov., C. inflatus sp. nov., C. stimpsoni sp. nov., C. pyriformis sp. nov., C. harpaeformis sp. nov., C. laurae sp. nov., C. robustus sp. nov., C. minimus sp. nov., C. ovoides sp. nov., C. mamillatus sp. nov., C. angustus sp. nov., C. profundus sp. nov., C. granum sp. nov., C. dentiferus sp. nov., C. alatus sp. nov., C. apertus sp. nov., C. contortus sp. nov., C. sinuosus sp. nov., C. pupoides sp. nov., C. lussii sp. nov., C. smithi sp. nov., C. serratus sp. nov., C. lachrymaformis sp. nov., and C. quinqueplicatus sp. nov. Among the 27 described species, 25 of them are only known from their holotype, one paratype from the type station is reported for C. subcylindricus, and two conspecific specimens collected from a non-type station are reported for C. lussii. Eight morphs represented by one or two shells are tentatively ascribed to some of the 27 recognized species. Among the 29 recognized species, 28 of them are found at bathyal levels, and only one of them (C. quinqueplicatus) was collected at a reef level, so the Cystiscus fauna of the Walters Shoal is characterized as bathyal fauna. From the fact that any other Cystiscus assemblage was ever studied from the bathyal of the Indo-Pacific Province, no direct comparison is made with external items, and the Cystiscus species of the Walters Shoal are only compared to each other.

Investigations into 3D-printed nautiloid-inspired pressure housings

The shell of the chambered nautilus is one of the few examples in nature of a biologically derived one-atmosphere pressure housing, which the animal uses to maintain neutral buoyancy via a series of sealed chambers. Extant species such as Nautilus pompilius live at depths from 200 to 800 m, and similar depth ranges have been hypothesized for their hyper diverse but extinct relatives, the ammonoids. Given the evolutionary success of these molluscan clades, their complex shell morphologies may reveal pressure-tolerant geometries comparable to the ‘ideal’ ones currently used in deep-sea marine robotics: simple spheres and cylinders, which have minimized surface area to volume ratio and easier manufacturability. We modeled and empirically tested 3D-printed bioinspired pressure housings for deep-sea applications using high resolution stereolithography 3D printing. These designs were modeled on the shells of N. pompilius and were compared to conventional 3D-printed spheres with similar wall thicknesses and implodable volumes. Two nautilus-inspired models with internal supports designed after their septal walls (one concave, one convex) had a higher-pressure tolerance compared to hollow models, but none outperformed spherical models with the same outer-wall thickness. Although spheres outperform the nautilus-inspired housings, the methods developed here show that pressure housings with complex geometries can be printed by additive manufacturing and empirically tested. From a biological perspective, this method can be a new tool for empirically testing viable depth tolerances for extinct coiled cephalopod morphologies.

Riverine flow rate drives widespread convergence in the shell morphology of imperiled freshwater mussels.

Frequent and strong morphological convergence suggests that determinism tends to supersede historical contingencies in evolutionary radiations. For many lineages living within the water column of rivers and streams, hydrodynamic forces drive widespread morphological convergence. Living below the sediment-water interface may release organisms from these hydrodynamic pressures, permitting a broad array of morphologies, and thus less convergence. However, we show here that the semi-infaunal freshwater mussels have environmentally determined convergence in shell morphology. Using 3D morphometric data from 715 individuals among 164 Nearctic species, we find that species occurring in rivers with high flow rates have evolved traits that resist dislodgement from their burrowed position in the streambed: thicker shells for their body size, with the thickest sector of the shell being the most deeply buried. Species occurring in low flow environments have evolved thinner and more uniformly thickened shells, corresponding to an alternative adaptation to dislodgement: increased burrowing efficiency. Within species, individuals also show increased shell thickness for their body size at higher flow rates, suggesting that ecophenotypy may, in part, be an important mechanism for establishing populations in new environments and thus evolutionary divergence in this highly imperiledinvertebrate group.

NiFe@Pd/C core–shell nanoparticles with enhanced catalytic activity toward glycerol electrooxidation in alkaline media

We synthesized NixFey@Pdz/C core–shell nanoparticles with different compositions to investigate their activity for glycerol oxidation. EDS and ICP analyses revealed divergences between the nominal and experimental compositions of the catalysts, indicating that the synthesis route was a little inefficient for depositing Ni-Fe. However, the addition of Ni-Fe to Pd increased its activity in glycerol oxidation. The Ni1.5Fe13.5@Pd85/C catalyst presents superior electrocatalytic performance, with a specific activity 1.28 times greater than that of Pd/C. In situ FTIR spectroscopy data revealed favorable formate and CO2 production on NiFe@Pd/C catalysts. Our research highlights the synergistic effect of composition and core–shell morphology on catalytic activity.

Decrypting the feared genus Hiatella (Bivalvia): South American species

Abstract Hiatella is among the most poorly understood bivalve genera. Most of the species remain known only from shell morphology, which has proved to be extremely variable in the group. Few studies have addressed their anatomy and biology, and no studies have combined morphological, anatomical and biological characters with molecular characters. This has led to the hiatellids all around the world being regarded as a single, widely distributed species. This contribution represents a step towards a better understanding of hiatellids worldwide by providing the first integrative study of the species occurring in southern South America. Three entities are recognized: Hiatella meridionalis, Hiatella barnea and Hiatella umbonata sp. nov. To understand their intraspecific variability, all the species are carefully described and figured, based on large series of specimens. Saxicava chilensis, Saxicava mollis, Saxicava lebruni and Saxicava subantarctica are considered synonyms of H. meridionalis; a lectotype for S. subantarctica is designated; and S. antarctica and S. frigida are regarded as nomina dubia. This study suggests that worldwide living hiatellids might have originated from South American species and that reduction/loss of hinge teeth during ontogeny and life on hard substrates or on/inside other invertebrates would represent derived traits within the genus Hiatella.

Beringian Freshwater Mussel Beringiana beringiana (Unionidae) in Northeast Asia

The origin of the fauna of Beringia is a notable biogeographical puzzle. Large mussels of the genus Beringiana inhabit both Northeast Asia and the northwestern part of North America and thus provide an important model to investigate the paleobiogeography of Beringia and the past and current intercontinental species exchanges. Data on Beringiana distribution, morphology, genetics, and taxonomy are fragmentary or questionable. In this study, we summarized the data on its distribution in Northeast Asia, performed genetic analysis (cox1), and studied the variation in the shell morphology in samples from four isolated populations, including the putative sympatric species. Over ten large enclaves of Beringiana are currently known in Northeast Asia (east to the Verkhoyansk Range), mostly in the lower reaches of large rivers in northeastern Yakutia, Kamchatka, Magadan Oblast, and Khabarovsk Krai. These enclaves are far apart (several hundreds of kilometers) because the mussel is associated with muddy sand or pebbly sand bottom substrates and spreads through its glochidia, which are parasitic on the fish. Shell morphology can be highly variable even in a single population, overlapping the diagnoses of several Beringiana species (which are currently not recognized as valid). Our analysis of the cox1 sequence in four populations identified all individuals as B. beringiana. We evaluated the possible current and probable Late Pleistocene–Early Holocene freshwater and marine pathways of B. beringiana dispersal through the area of former Beringia, including the current intercontinental migration of glochidia on fish.

Synthesis and properties of crosslinked waterborne polyurethane/acrylate copolymer latexes using AIBN initiator based on a solvent-/emulsifier-free method

In this study, a series of crosslinked waterborne polyurethane/acrylate copolymer latexes with different compositions were fabricated via emulsion polymerization using oil-soluble initiator (AIBN) based on a solvent-/emulsifiers-free method. Using the blend of styrene (St), butyl acrylate (BA) and crosslinkers (pentaerythritol triacrylate (PET3A) and pentaerythritol tetraacrylate (PET4A)) instead of acetone as a diluent and modifier, polyurethane prepolymers terminated with hydroxyethyl acrylate composite emulsions were prepared using polypropylene glycol (PPG), toluene diisocyanate (TDI), 2,2-dihydroxymethylpropionic acid (DMPA) and diethylene glycol (DEG) without other solvents. It was found that for all the emulsion polymerization of waterborne polyurethane and acrylates initiated by AIBN, the monomer conversions exceeded 96% when the concentration of AIBN was in the range of 0.5% to 0.9% (w/w) and the optimal reaction temperature was 75 °C. The introduction of St, BA and crosslinkers would form the polymer network, improving the tensile strength, water absorption of the copolymer latex films. Dynamic light scattering analyses showed that the copolymer latexes exhibited a unimodal distribution and showed no precipitates and unstable aggregates. The average particle size distribution was in the range of 131–154 nm. Transmission electron microscopy studies have confirmed the similar results and the latex particles possessed the core–shell morphology structure.

Characterizing the Ligand Shell Morphology of PEG-Coated ZnO Nanocrystals Using FRET Spectroscopy.

Poly(ethylene glycol) (PEG) ligands can inhibit proteins and other biomolecules from adhering to underlying surfaces, making them excellent surface ligands for nanocrystal (NC)-based drug carriers. Quantifying the PEG ligand shell morphology is important because its structure determines the permeability of biomolecules through the shell to the NC surface. However, few in situ analytical tools can reveal whether the PEG ligands form either an impenetrable barrier or a porous coating surrounding the NC. Here, we present a Förster resonance energy transfer (FRET) spectroscopy-based approach that can assess the permeability of molecules through PEG-coated ZnO NCs. In this approach, ZnO NCs serve as FRET donors, and freely diffusing molecules in the bulk solution are FRET acceptors. We synthesized a series of variable chain length PEG-silane-coated ZnO NCs such that the longest chain length ligands far exceed the Förster radius (R0), where the energy transfer (EnT) efficiency is 50%. We quantified the EnT efficiency as a function of the ligand chain length using time-resolved photoluminescence lifetime (TRPL) spectroscopy within the framework of FRET theory. Unexpectedly, the longest PEG-silane ligand showed equivalent EnT efficiency as that of bare, hydroxyl-passivated ZnO NCs. These results indicate that the "rigid shell" model fails and the PEG ligand shell morphology is more likely porous or in a patchy "mushroom state", consistent with transmission electron microscopy data. While the spectroscopic measurements and data analysis procedures discussed herein cannot directly visualize the ligand shell morphology in real space, the in situ spectroscopy approach can provide researchers with valuable information regarding the permeability of species through the ligand shell under practical biological conditions.

Freshwater pulmonate snails and their potential role as trematode intermediate host in a cercarial dermatitis outbreak in Southern Thailand

This study aimed to investigate the pulmonate snail species in the vicinity of the cercarial dermatitis outbreak area in southern Thailand. In 2020, an outbreak of cercarial dermatitis was reported in Chana district, Songkhla Province, caused by the ruminant schistosome Schistosoma indicum and its snail intermediate host Indoplanorbis exustus. In the present study, 1,175 pulmonate snails were collected between October 2021 and October 2022 from five provinces covering 34 locations in southern Thailand. Seven pulmonate snail species were identified based on shell morphology, including Amerianna carinata, Gyraulus bakeri, G. convexiusculus, G. hubendicki, Physella acuta, Indoplanorbis exustus, and Radix rubiginosa. Among these snails, eight species, and five types of cercariae were identified, viz. type (i) Echinostome cercariae consisted of Echinoparyphium recurvatum, Echinostoma spiniferum, and E. revolutum, type (ii) Brevifurcate-apharyngeate cercariae consisted of Schistosoma indicum and S. spindale, type (iii) Brevifurcate-pharyngeate-clinostomatoid-cercariae was represented by Clinostomum giganticum, type (iv) Longifurcate–pharyngeate cercariae (strigea cercaria) was Diplostomum baeri eucaliae, and type (v) Ophthalmoxiphidiocercaria. Among the seven pulmonated snail species, three were found to be infected, viz. G. convexiusculus, I. exustus, and R. rubiginosa, with infection rates of 1.14% (2/176), 0.25% (2/802), and 4.02% (7/174), respectively.

The regulatory effect of NF-κB signaling pathway on biomineralization and shell regeneration in pearl oyster, Pinctada fucata

Pinctada fucata is an important pearl production shellfish in aquaculture. The formation of shells and pearls is a hot research topic in biomineralization, and matrix proteins secreted by the mantle tissues play the key role in this process. However, upstream regulatory mechanisms of transcription factors on the matrix protein genes remain unclear. Previous studies have shown that NF-κB signaling pathway regulated biomineralization process through expression regulation of specific matrix proteins, including Nacrein, Prismalin-14 and MSI60. In this study, we systematically investigated the regulatory effect of the NF-κB signaling pathway key factor Pf-Rel and inhibitory protein poI-κB on the biomineralization and shell regeneration process. We applied RNA interference and antibody injection assays to study in vivo function of transcription factor Pf-Rel and characterized shell morphology changes using scanning electron microscopy and Raman spectroscopy. We found that transcription factor Pf-Rel plays a positive regulatory role in the growth regulation of the prismatic and nacreous layers, while the function of inhibitory protein poI-κB is to prevent excessive growth and accumulation of both layers. RNA-seq was conducted based on RNA interference animal model to identify potential regulatory genes by transcription factor Pf-Rel. Shell damage repair experiments were performed to simulate shell regeneration process, and observations of newly formed shells revealed that NF-κB signaling pathway had different functions at different times. This study provides us with a more macroscopic perspective based on transcription factors to investigate biomineralization and shell regeneration.

The Strain Effects and Interfacial Defects of Large ZnSe/ZnS Core/Shell Nanocrystals.

The shell growth of large ZnSe/ZnS nanocrystals( is of great importance in the pursuit of pure-blue emitters for display applications, however, suffers from the challenges of spectral blue-shifts and reduced photoluminescence quantum yields. In this work, the ZnS shell growth on different-sized ZnSe cores is investigated. By controlling the reactivity of Zn and S precursors, the ZnS shell growth can be tuned from defect-related strain-released to defect-free strained mode, corresponding to the blue- and red-shifts of resultant nanocrystals respectively. The shape of strain-released ZnSe/ZnS nanocrystals can be kept nearly spherical during the shell growth, while the shape of strained nanocrystals evolutes from spherical into island-like after the critical thickness. Furthermore, the strain between ZnSe core and ZnS shell can convert the band alignment from type-I into type-II core/shell structure, resulting in red-shifts and improved quantum yield. By correlating the strain effects with interfacial defects, a strain-released shell growth model is proposed to obtain large ZnSe/ZnS nanocrystals with isotropic shell morphology.

Life in a changing environment: dreissenids’ feeding response to different temperature

Invasive species have far-reaching consequences for whole ecosystems. The two dreissenids zebra and quagga mussels are two of the most successful invaders in aquatic systems. Quagga mussels can colonize deeper parts of a lake while zebra mussels prefer shallow areas. Both species show large variability in shell morphology, but only quagga mussels show a shallow and deep-water morphotype. The aim of this study is to investigate the depth adaptation of quagga mussels and the potential filtration advantage of the quagga mussel compared to the zebra mussel. We conducted common garden experiments, where we measured filtration rates at different temperatures of quagga mussels collected from different water depths and compared them to zebra mussel from 1m depth. We found filtration rates to be strongly temperature dependent, and in particular, lower at 4 °C. Overall, zebra mussels fed less than quaggas. Quagga mussels collected from 1 m depth fed more at higher temperature than quaggas from 30 and 60 m. We hypothesize that deep-water quagga mussels are less sensitive to lower temperature and/or constrained to modify filtration rates at higher temperatures.

Phylogenetic relationships of Terranigra Radoman, 1978 (Truncatelloidea: Hydrobiidae)

Terranigra kosovica Radoman, 1978, was known from four localities in Kosovo. The monotypic genus was described on the basis of genital morphology. We collected T. kosovica at a new locality, about 40 km from its type locality. The shell morphology, as well as the soft part morphology and anatomy were identical to that described by Radoman. The molecular markers mitochondrial cytochrome oxidase subunit I (COI) and nuclear histone (H3) resolved phylogenetic position of Terranigra as a sister clade to Agrafia Szarowska et Falniowski, 2011.

Integrative Analysis of Retusa pertenuis (Heterobranchia: Cephalaspidea) from Arctic and Russian Far East Seas with Discussion of Its Morphology, Validity and Population Structure

Retusa pertenuis is still formally considered a junior subjective synonym of Retusa obtusa, despite previous data indicating R. pertenuis and R. obtusa differ significantly in copulatory system morphology. In this paper, we study the species identity and population structure of R. pertenuis with an integrative approach combining morphological and molecular data. The external morphology, head copulatory system and gizzard plates were studied using light microscopy and scanning electron microscopy. We also obtained two mitochondrial (COI and 16S) and two nuclear (H3 and 28S) markers to test the monophyly of R. pertenuis and R. obtusa. Populations from the White Sea, Sea of Okhotsk and Sea of Japan were studied using COI and 18S molecular markers. Our results show that Retusa obtusa sensu lato represents a species complex of at least four species: the nominative species occurring in the North Atlantic, the widely distributed R. pertenuis and two additional species whose identities should be clarified in further studies. Retusa pertenuis geographic range encompasses the North Atlantic, Eurasia’s northern seas, the Canadian Arctic, the Bering Sea, the Sea of Okhotsk and the Sea of Japan. Within R. pertenuis’s range, this species demonstrates a wide variability in shell morphology.