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Skin, the largest organ in the human body, is a crucial protective barrier that plays essential roles in thermoregulation, sensation, and immune defence. This complex organ undergoes intricate processes of development. Skin development initiates during the embryonic stage, orchestrated by molecular cues that control epidermal specification, commitment, stratification, terminal differentiation, and appendage growth. Key signalling pathways are integral in coordinating the development of the epidermis, hair follicles, and sweat glands. The complex interplay among these pathways is vital for the appropriate formation and functionality of the skin. Disruptions in multiple molecular pathways can give rise to a spectrum of skin diseases, from congenital skin disorders to cancers. By delving into the molecular mechanisms implicated in developmental processes, as well as in the pathogenesis of diseases, this narrative review aims to present a comprehensive understanding of these aspects. Such knowledge paves the way for developing innovative targeted therapies and personalised treatment approaches for various skin conditions.

Autotomy of appendages is a self-protection mechanism in crustaceans, which is defined as the reflexive loss of a limb in response to predation, competition, or other environmental factors. Single-limb injuries were the most common among the species surveyed in the present study, and the chelicerae were the most frequently lost appendages. After autotomy, hormones and signaling pathways are altered. Loss of limbs can affect foraging efficiency, although cheliped loss may be compensated by shifting to alternative prey or using both motor and oral appendages. In heterogeneous species, the loss of the major chelae may affect the selectivity of feeding. Autotomy can affect crustacean growth by reducing size increases at molting and altering the timing of ecdysis. In commercial production, removing chelicerae is an effective strategy to reduce cannibalism, and production of soft-shell crabs can be increased via autotomy. After autotomy, a new limb will regrow through regeneration and molting. This process involves the regulation of hormones, regrowth of nerves, and a number of signaling pathways that include the Wnt/β-catenin signaling pathway and transforming growth factor β signaling pathway. Crustaceans are somewhat different from vertebrates in terms of regeneration. This review provides theoretical guidance about autotomy and regeneration applied in artificial aquaculture, and we offer several suggestions for future research on autotomy and regeneration in crustaceans. [ABSTRACT FROM AUTHOR]

In this paper, we present an overview of numerical simulation methods for the flow around typical underwater vehicles at high Reynolds numbers, which highlights the dominant flow structures in different regions of interest. This overview covers the forebody, midbody, stern, wake region, and appendages and summarizes flow phenomena, including laminar-to-turbulent transition, turbulent boundary layers, flow under the influence of curvatures, wake interactions, and all associated complex vortex structures. Furthermore, the current issues and challenges of capturing these flow structures are addressed. This overview provides a deep insight into the use of numerical simulation methods, including the Reynolds-averaged Navier–Stokes (RANS) method, large eddy simulation (LES) method, and the hybrid RANS/LES method, and evaluates their applicability in capturing detailed flow features. [ABSTRACT FROM AUTHOR]

Purpose: Torsion of the appendix testis or epididymis is a cause of acute scrotum in children. Ultrasonography with color Doppler is the first-choice modality for diagnosis. However, this method requires skill and experience to make a diagnosis with confidence. Recently, contrast-enhanced ultrasonography for diagnosis in various fields has been reported. However, to our knowledge, there has been no report of this method being used to diagnose torsion of the appendix testis or epididymis. The purpose of this study was to retrospectively examine contrast-enhanced ultrasonographic findings in torsion of the appendix testis or epididymis. Methods: Patients who underwent contrast-enhanced ultrasonography for torsion of the appendix testis or epididymis at our institution between April 2010 and April 2023 were enrolled in this study (n = 12). Contrast-enhanced ultrasonography findings of the affected appendage and the testis parenchyma were examined retrospectively. Results: The parenchyma of the testes was notably enhanced in all the cases. However, 9 of the 12 cases showed that the appendage with torsion was not enhanced at all. In the remaining three cases, only slight enhancement was seen. Nevertheless, it was notably less than that of the parenchyma of the testis. Conclusion: Our findings indicated that contrast-enhanced ultrasonography may be an easy and reliable method for diagnosing torsion of the appendix testis or epididymis. [ABSTRACT FROM AUTHOR]

Spiders constitute more than 49,000 described species distributed all over the world, and all ecological environments. Their order, Araneae, is defined by a set of characteristics with no parallel among their arachnid counterparts (e.g., spinnerets, silk glands, chelicerae that inoculate venom, among others). Changes in developmental pathways often underlie the evolution of morphological synapomorphies, and as such spiders are a promising model to study the role of developmental genes in the origin of evolutionary novelties. With that in mind, we investigated changes in the evolutionary regime of a set of six developmental genes, using spiders as our model. The genes were mainly chosen for their roles in spinneret ontogeny, yet they are pleiotropic, and it is likely that the origins of other unique morphological phenotypes are also linked to changes in their sequences. Our results indicate no great differences in the selective pressures on those genes when comparing spiders to other arachnids, but a few site‐specific positive selection evidence were found in the Araneae lineage. These findings lead us to new insights on spider evolution that are to be further tested. Research highlights: We looked for information on spinneret origins with a molecular evolution approach on development genes.We observed some codons with evidence of positive selection in some of them. These should be further studied for the spider‐specific roles. [ABSTRACT FROM AUTHOR]

Chitin is the major scaffolding component of the insect cuticle. Ultrastructural analyses revealed that chitin adopts a quasi-crystalline structure building sheets of parallel running microfibrils. These sheets called laminae are stacked either helicoidally or with a preferred orientation of the microfibrils. Precise control of chitin synthesis is mandatory to ensure the correct chitin assembly and in turn proper function of cuticular structures. Thus, evaluation of chitin-metabolism deficient phenotypes is a key to our understanding of the function of the proteins and enzymes involved in cuticle architecture and more generally in cuticle biology in insects. Usually, these phenotypes have been assessed using electron microscopy, which is time-consuming and labor intensive. This stresses the need for rapid and straightforward histological methods to visualize chitin at the whole tissue level. Here, we propose a simple method of chitin staining using the common polysaccharide marker Fluorescent brightener 28 (FB28) in whole-mount Drosophila melanogaster. To overcome the physical barrier of FB28 penetration into the cuticle, staining is performed at 65°C without affecting intactness. We quantify FB28 fluorescence in three functionally different cuticular structures namely wings, dorsal abdomens and forelegs by fluorescence microscopy. We find that, as expected, cuticle pigmentation may interfere with FB28 staining. Down-regulation of critical genes involved in chitin metabolism, including those coding for chitin synthase or chitinases, show that FB28 fluorescence reflects chitin content in these organs. We think that this simple method could be easily applied to a large variety of intact insects. [ABSTRACT FROM AUTHOR]

Omental infarction and epiploic appendagitis are rare causes of acute abdominal pain in the pediatric population. Radiological evaluation is necessary to establish a specific diagnosis and to differentiate appendicitis from these conditions as they can be often managed conservatively without surgical intervention.

Chitin is the major scaffolding component of the insect cuticle. Ultrastructural analyses revealed that chitin adopts a quasi-crystalline structure building sheets of parallel running microfibrils. These sheets called laminae are stacked either helicoidally or with a preferred orientation of the microfibrils. Precise control of chitin synthesis is mandatory to ensure the correct chitin assembly and in turn proper function of cuticular structures. Thus, evaluation of chitin-metabolism deficient phenotypes is a key to our understanding of the function of the proteins and enzymes involved in cuticle architecture and more generally in cuticle biology in insects. Usually, these phenotypes have been assessed using electron microscopy, which is time-consuming and labor intensive. This stresses the need for rapid and straightforward histological methods to visualize chitin at the whole tissue level. Here, we propose a simple method of chitin staining using the common polysaccharide marker Fluorescent brightener 28 (FB28) in whole-mount Drosophila melanogaster. To overcome the physical barrier of FB28 penetration into the cuticle, staining is performed at 65°C without affecting intactness. We quantify FB28 fluorescence in three functionally different cuticular structures namely wings, dorsal abdomens and forelegs by fluorescence microscopy. We find that, as expected, cuticle pigmentation may interfere with FB28 staining. Down-regulation of critical genes involved in chitin metabolism, including those coding for chitin synthase or chitinases, show that FB28 fluorescence reflects chitin content in these organs. We think that this simple method could be easily applied to a large variety of intact insects.

Skin, the largest organ in the human body, is a crucial protective barrier that plays essential roles in thermoregulation, sensation, and immune defence. This complex organ undergoes intricate processes of development. Skin development initiates during the embryonic stage, orchestrated by molecular cues that control epidermal specification, commitment, stratification, terminal differentiation, and appendage growth. Key signalling pathways are integral in coordinating the development of the epidermis, hair follicles, and sweat glands. The complex interplay among these pathways is vital for the appropriate formation and functionality of the skin. Disruptions in multiple molecular pathways can give rise to a spectrum of skin diseases, from congenital skin disorders to cancers. By delving into the molecular mechanisms implicated in developmental processes, as well as in the pathogenesis of diseases, this narrative review aims to present a comprehensive understanding of these aspects. Such knowledge paves the way for developing innovative targeted therapies and personalised treatment approaches for various skin conditions.

The first Silurian trilobite known with soft parts preserved, a Dalmanites species, is described from the Herefordshire Lagerstätte. Biramous appendages and much of the alimentary system are evident. High‐fidelity three‐dimensional preservation reveals a novel arrangement of the exopod, in which successive filaments are connected by a presumed membrane. This morphology explains a misinterpretation of the exopod as supporting spiral structures, originally reported nearly 150 years ago. Comparison with other trilobite limbs indicates that the exopod morphology of Dalmanites is present in other members of Phacopida. The function of the exopod is considered to be primarily respiratory. [ABSTRACT FROM AUTHOR]

One of the most extensive species radiations in the tardigrade evolution took place in the Echiniscus phylogenetic line, which contains the genus Echiniscus with over 120 species described to date. The internal classification of Echiniscus is historically based on two major sources of variability: chaetotaxy, that is the arrangement and the shape of trunk appendages, and the sculpturing of dorsal plates. These two criteria allowed for the delineation of species complexes, such as the blumi-canadensis or the spinulosus group. Recent phylogenetic analyses confirmed that they represent monophyletic lineages. However, the affinities of some species that have not been sequenced are not straightforward given their uncommon morphologies. In this paper, we present five Echiniscus species found in Argentina, two of which constitute such exemplary cases. Echiniscus aonikenk sp. nov. exhibits extraordinarily elongated cirri A , exceeding 50% of the body length, and dorsoventrally flattened trunk spines, including particularly wide spines E. The species is a probable sister group of the spinulosus complex. Furthermore, Echiniscus evelinae de Barros, 1942, reported here only third time ever, is characterised by an extreme elongation of cirri E , often exceeding the body length, and by autapomorphic dorsal sculpturing comprising epicuticular granules, pseudopores, distinct endocuticular reticulum and pillars. Analogously to E. aonikenk sp. nov. , E. evelinae apparently constitutes a separate evolutionary lineage. Finally, Echiniscus pellucidus sp. nov. (the merokensis complex), Echiniscus peruvianus Binda & Pilato, 1994 syn. nov. (the testudo complex) and Echiniscus manuelae da Cunha & do Nascimento Ribeiro, 1962 (the spinulosus complex) are analysed. Morphological peculiarities revealed in this study are discussed in the light of the Echiniscus taxonomy. [ABSTRACT FROM AUTHOR]

The evolution of the appendages during the fin-to-limb transition has been extensively studied, yet the majority of studies focused on the skeleton and the fossil record. Whereas the evolution of the anatomy of the appendicular musculature has been studied, the changes in the muscular architecture during the fin-to-limb transition remain largely unstudied, yet may provide important new insights. The fin-to-limb transition is associated with the appearance of a new mode of locomotion and the associated shift from pectoral to pelvic dominance. Here, we propose ways to investigate this question and review data on muscle mass and muscle architecture of the pectoral and pelvic muscles in extant vertebrates. We explore whether changes in appendage type are associated with changes in the muscular architecture and the relative investment in different muscle groups. These preliminary data show a general increase in the muscle mass of the appendages relative to the body mass during the fin-to-limb transition. The locomotor shift suggested to occur during the fin-to-limb transition appears supported by our preliminary data since in “fish” the pectoral fins are heavier than the pelvic fins, whereas in tetrapods, the forelimb muscles are less developed than the hind limb muscles. Finally, a shift in the investment in different muscle groups with an increase of the contribution of the superficial groups in tetrapods compared to “fish” appears to take place. Our study highlights the potential of investigating quantitative features of the locomotor muscles, yet also demonstrates the lack of quantitative data allowing to test these ideas.

The genera Menisporopsis, Multiguttulispora and Tainosphaeria (Chaetosphaeriaceae) are saprobes inhabiting decaying plant material. This study is based on an integrated morpho-molecular characterisation to assess their generic concepts and explore phylogenetic relationships. Menisporopsis is revealed as polyphyletic, and species with 1-septate conidia and synnemata growing unilaterally along the seta are placed in the new segregate genus Arcuatospora. Codinaea dimorpha and C. triseptata are shown to be congeneric with Multiguttulispora sympodialis, the type species. Two new combinations are proposed: M. sympodialis is found conspecific with M. dimorpha. The Tainosphaeria complex is resolved into three genera. We found that the morphological separation of three groups within the genus is consistent with phylogenetic relationships. Tainosphaeria s. str. is accepted with five species. Tainosphaeria aseptata and T. lunata are transferred to the newly erected Phialoturbella, whereas T. obclavata is revealed as conspecific with Phialogeniculata guadalcanalensis, reducing it to a synonym. A new genus Flectospora is erected for a chloridium-like fungus nested in the Tainosphaeria clade. Based on molecular evidence, we show that asymmetrical, scolecosporous ascospores are a unique teleomorphic characteristic among family members. Therefore, we propose new combinations for Chaetosphaeria hispida in Paragaeumannomyces and Ch. spinosa in the new genus Ericiosphaeria, both exhibiting this rare morphotype. [ABSTRACT FROM AUTHOR]

Omental infarction and epiploic appendagitis are rare causes of acute abdominal pain in the pediatric population. Radiological evaluation is necessary to establish a specific diagnosis and to differentiate appendicitis from these conditions as they can be often managed conservatively without surgical intervention. [ABSTRACT FROM AUTHOR]

Known from at least the Silurian (c. 435 Ma) up to the Late Cretaceous (c. 85 Ma), thylacocephalans are among the most intriguing fossil euarthropods. They are characterized by a prominent shield enveloping most of the body, hypertrophied compound eyes, three pairs of large, raptorial appendages and a trunk with 8–22 stout segments bearing appendages. Despite this knowledge of their anatomy, the phylogenetic affinities of Thylacocephala are controversial due to a lack of knowledge on their body organization and tagmosis. This study focuses on Mayrocaris bucculata Polz, 1994 from the Solnhofen Lagerstätte, Germany (c. 150 Ma, early Tithonian, Jurassic). We document new specimens of Mayrocaris bucculata from the Solnhofener Plattenkalke sensu lato and provide new descriptions for previously reported specimens. We demonstrate that the raptorial appendages of Thylacocephala are most probably maxillulae, maxillae and maxillipeds. Additionally, we report new details on the posterior trunk appendages, including the description of a paddle-like proximal part and of a rod-like distal part, but also of a specialized terminal trunk appendage. These new findings, in addition to the reinterpretation of a cephalic appendage of Clausocaris lithographica as a possible mandible, are essential for a better understanding of the body organization in thylacocephalans and their phylogenetic affinities within Eucrustacea. [ABSTRACT FROM AUTHOR]

The similarity in the genetic regulation of arthropod and vertebrate appendage formation has been interpreted as the product of a plesiomorphic gene network that was primitively involved in bilaterian appendage development and co-opted to build appendages (in modern phyla) that are not historically related as structures. Data from lophotrochozoans are needed to clarify the pervasiveness of plesiomorphic appendage-forming mechanisms. We assayed the expression of three arthropod and vertebrate limb gene orthologs, Distal-less (Dll), dachshund (dac), and optomotor blind (omb), in direct-developing juveniles of the polychaete Neanthes arenaceodentata. Parapodial Dll expression marks pre-morphogenetic notopodia and neuropodia, becoming restricted to the bases of notopodial cirri and to ventral portions of neuropodia. In outgrowing cephalic appendages, Dll activity is primarily restricted to proximal domains. Dll expression is also prominent in the brain. dac expression occurs in the brain, nerve cord ganglia, a pair of pharyngeal ganglia, presumed interneurons linking a pair of segmental nerves, and in newly differentiating mesoderm. Domains of omb expression include the brain, nerve cord ganglia, one pair of anterior cirri, presumed precursors of dorsal musculature, and the same pharyngeal ganglia and presumed interneurons that express dac. Contrary to their roles in outgrowing arthropod and vertebrate appendages, Dll, dac, and omb lack comparable expression in Neanthes appendages, implying independent evolution of annelid appendage development. We infer that parapodia and arthropodia are not structurally or mechanistically homologous (but their primordia might be), that Dll’s ancestral bilaterian function was in sensory and central nervous system differentiation, and that locomotory appendages possibly evolved from sensory outgrowths.

The genus Codinaea is a phialidic, dematiaceous hyphomycete known for its intriguing morphology and turbulent taxonomic history. This polyphasic study represents a new, comprehensive view on the taxonomy, systematics, and biogeography of Codinaea and its relatives. Phylogenetic analyses of three nuclear loci confirmed that Codinaea is polyphyletic. The generic concept was emended; it includes four morphotypes that contribute to its morphological complexity. Ancestral inference showed that the evolution of some traits is correlated and that these traits previously used to delimit taxa at the generic level occur in species that were shown to be congeneric. Five lineages of Codinaea-like fungi were recognized and introduced as new genera: Codinaeella, Nimesporella, Stilbochaeta, Tainosphaeriella, and Xyladelphia. Dual DNA barcoding facilitated identification at the species level. Codinaea and its segregates thrive on decaying plants, rarely occurring as endophytes or plant pathogens. Environmental ITS sequences indicate that they are common in bulk soil. The geographic distribution found using GlobalFungi database was consistent with known data. Most species are distributed in either the Holarctic realm or tropical geographic regions. The ancestral climatic zone was temperate, followed by transitions to the tropics; these fungi evolved primarily in Eurasia and Americas, with subsequent transitions to Africa and Australasia.

Australian fauna is widely recognised for its high levels of endemism, and tardigrade fauna does not seem to be an exception in this respect. The richness of xerothermic habitats in Australia, often occupied by heterotardigrade family Echiniscidae, entails high abundance and uniqueness of echiniscid assemblages. A new gonochoristic/dioecious echiniscid species was found in large numbers in samples from Western Australia. Echiniscus siticulosussp. nov., characterised by dominant large cuticular pores in the dorsal sculpture and appendages in the form of spines, represents the spinulosus group but can be distinguished from the known members of this species complex by a unique combination of traits: peculiar faceting of the caudal plate formed by ridge-shaped epicuticular extensions and pore morphology. An amended phenotypic diagnosis of Echiniscus spiniger Richters 1904, the species morphologically most similar to the new species, is also presented. [ABSTRACT FROM AUTHOR]

The pauropod family Eurypauropodidae Ryder, 1879 is recorded from Tibet, China for the first time. In this study, a new species Samarangopus zhongi sp. nov. is described and illustrated from Motuo County, southeastern Tibet of China. It is distinguished from other species in this genus by having one pair of spiniform appendages on the sternum of the last trunk segment, 28-34 marginal protuberances on tergite I, the distal quarter of bothriotricha T3 golf-club-shaped, and the leaf-shaped seta st on tergum of pygidium. In addition, Samarangopus canalis Scheller, 2009 is newly recorded from China. [ABSTRACT FROM AUTHOR]

Spiders are equipped with a large number of innervated cuticular specializations, which respond to various sensory stimuli. The physiological function of mechanosensory organs has been analysed in great detail in some model spider species (e.g. Cupiennius salei); however, much less is known about the distribution and function of chemosensory organs. Furthermore, our knowledge on how the sense organ pattern develops on the spider appendages is limited. Here we analyse the development of the pattern and distribution of six different external mechano- and chemosensory organs in all postembryonic stages and in adult male and female spiders of the species Parasteatoda tepidariorum. We show that except for small mechanosensory setae, external sense organs appear in fixed positions on the pedipalps and first walking legs, arranged in longitudinal rows along the proximal-distal axis or in invariable positions relative to morphological landmarks (joints, distal tarsal tip). A comparison to other Entelegynae spiders shows that these features are conserved. We hope that this study lays the foundation for future molecular analysis to address the question how this conserved pattern is generated. [ABSTRACT FROM AUTHOR]

Surface sensing in bacteria is a precursor to the colonization of biotic and abiotic surfaces, and an important cause of drug resistance and virulence. As a motile bacterium approaches and adheres to a surface from the bulk fluid, the mechanical forces that act on it change. Bacteria are able to sense these changes in the mechanical load through a process termed mechanosensing. Bacterial mechanosensing has featured prominently in recent literature as playing a key role in surface sensing. However, the changes in mechanical loads on different parts of the cell at a surface vary in magnitudes as well as in signs. This confounds the determination of a causal relationship between the activation of specific mechanosensors and surface sensing. Here, we explain how contrasting mechanical stimuli arise on a surface-adherent cell and how known mechanosensors respond to these stimuli. The evidence for mechanosensing in select bacterial species is reinterpreted, with a focus on mechanosensitive molecular motors. We conclude with proposed criteria that bacterial mechanosensors must satisfy to successfully mediate surface sensing. Image 1 • Bacterial mechanosensing has been implicated in surface sensing although a causal relationship has not been established. • We discuss how prominent modes of surface attachments cause mechanical load changes of varying magnitudes and signs. • Current evidence for mechanosensing is reinterpreted with the help of a load-change analysis for molecular motors. • Alternate explanations are offered for surface sensing that does not involve mechanosensing. [ABSTRACT FROM AUTHOR]

The genera Menisporopsis, Multiguttulispora and Tainosphaeria (Chaetosphaeriaceae) are saprobes inhabiting decaying plant material. This study is based on an integrated morpho-molecular characterisation to assess their generic concepts and explore phylogenetic relationships. Menisporopsis is revealed as polyphyletic, and species with 1-septate conidia and synnemata growing unilaterally along the seta are placed in the new segregate genus Arcuatospora. Codinaea dimorpha and C. triseptata are shown to be congeneric with Multiguttulispora sympodialis, the type species. Two new combinations are proposed: M. sympodialis is found conspecific with M. dimorpha. The Tainosphaeria complex is resolved into three genera. We found that the morphological separation of three groups within the genus is consistent with phylogenetic relationships. Tainosphaeria s. str. is accepted with five species. Tainosphaeria aseptata and T. lunata are transferred to the newly erected Phialoturbella, whereas T. obclavata is revealed as conspecific with Phialogeniculata guadalcanalensis, reducing it to a synonym. A new genus Flectospora is erected for a chloridium-like fungus nested in the Tainosphaeria clade. Based on molecular evidence, we show that asymmetrical, scolecosporous ascospores are a unique teleomorphic characteristic among family members. Therefore, we propose new combinations for Chaetosphaeria hispida in Paragaeumannomyces and Ch. spinosa in the new genus Ericiosphaeria, both exhibiting this rare morphotype.

For a ship undergoing roll motion at a resonance frequency, the roll restoring moment and virtual moment of inertia counteract each other and only the damping moment resists the roll exciting moments. Hence, accurate computation of the roll damping moment improves the roll motion prediction. There are several methods to calculate the damping moment; however, most of them fail to consider the viscous effects, such as the potential theory-based method. The experimental measurements take into account the viscous effect; however, they are expensive. The Computational Fluid Dynamics (CFD) method is an alternative to accurately consider the viscous effect. In this study, a CFD approach based on harmonic exciting roll motion technique is adopted to compute the roll motion characteristics and damping coefficients at different conditions. The impact of appendages, Froude number, and degrees of freedom on roll motion characteristics and damping coefficients are investigated for the model scale and full scale to study the scale effects. The results at the model scale are compared against experimental measurements and good correlation was found. [ABSTRACT FROM AUTHOR]

A moss sample from the local biodiversity hotspot in lowland rainforest in the vicinity of Amber Mountain, Madagascar, yielded the discovery of two Echiniscus C.A.S. Schultze, 1840 species, of which one is new to science. Echiniscus succineus sp. nov. is related to other members of the spinulosus group, but differs from them by the highly complicated structure of the dorsal plates, with intricately thickened parts of the armour forming ornamented pattern. The validity of the intraporal dark rings as a taxonomic trait is discussed in the context of the recovered intraspecific variability for the new taxon. Besides, rare Echiniscus africanus Murray, 1907 is reported for the first time from the island. [ABSTRACT FROM AUTHOR]

Abstract Biofilm formation is initiated by adhesion of individual bacteria to a surface. However, surface adhesion alone is not sufficient to form the complex community architecture of a biofilm. Surface-sensing creates bacterial awareness of their adhering state on the surface and is essential to initiate the phenotypic and genotypic changes that characterize the transition from initial bacterial adhesion to a biofilm. Physico-chemistry has been frequently applied to explain initial bacterial adhesion phenomena, including bacterial mass transport, role of substratum surface properties in initial adhesion and the transition from reversible to irreversible adhesion. However, also emergent biofilm properties, such as production of extracellular-polymeric-substances (EPS), can be surface-programmed. This review presents a four-step, comprehensive description of the role of physico-chemistry from initial bacterial adhesion to surface-programmed biofilm growth: (1) bacterial mass transport towards a surface, (2) reversible bacterial adhesion and (3) transition to irreversible adhesion and (4) cell wall deformation and associated emergent properties. Bacterial transport mostly occurs from sedimentation or convective-diffusion, while initial bacterial adhesion can be described by surface thermodynamic and Derjaguin−Landau−Verwey−Overbeek (DLVO)-analyses, considering bacteria as smooth, inert colloidal particles. DLVO-analyses however, require precise indication of the bacterial cell surface, which is impossible due to the presence of bacterial surface tethers, creating a multi-scale roughness that impedes proper definition of the interaction distance in DLVO-analyses. Application of surface thermodynamics is also difficult, because initial bacterial adhesion is only an equilibrium phenomenon for a short period of time, when bacteria are attached to a substratum surface through few surface tethers. Physico-chemical bond-strengthening occurs in several minutes leading to irreversible adhesion due to progressive removal of interfacial water, conformational changes in cell surface proteins, re-orientation of bacteria on a surface and the progressive involvement of more tethers in adhesion. After initial bond-strengthening, adhesion forces arising from a substratum surface cause nanoscopic deformation of the bacterial cell wall against the elasticity of the rigid peptidoglycan layer positioned in the cell wall and the intracellular pressure of the cytoplasm. Cell wall deformation not only increases the contact area with a substratum surface, presenting another physico-chemical bond-strengthening mechanism, but is also accompanied by membrane surface tension changes. Membrane-located sensor molecules subsequently react to control emergent phenotypic and genotypic properties in biofilms, most notably adhesion-associated ones like EPS production. Moreover, also bacterial efflux pump systems may be activated or mechano-sensitive channels may be opened upon adhesion-induced cell wall deformation. The physico-chemical properties of the substratum surface thus control the response of initially adhering bacteria and through excretion of autoinducer molecules extend the awareness of their adhering state to other biofilm inhabitants who subsequently respond with similar emergent properties. Herewith, physico-chemistry is not only involved in initial bacterial adhesion to surfaces but also in what we here propose to call "surface-programmed" biofilm growth. This conclusion is pivotal for the development of new strategies to control biofilm formation on substratum surfaces, that have hitherto been largely confined to the initial bacterial adhesion phenomena. Graphical abstract Unlabelled Image Highlights • Physico-chemistry dictates initial bacterial adhesion to substratum surfaces • Bond-strengthening leads to irreversible adhesion of bacteria (and inert colloids) • Through quorum-sensing, bacteria share information on substratum surface properties • Substratum surface properties program emergent biofilm properties • Regarding bacteria as inert colloids, does not yield a generalized biofilm model [ABSTRACT FROM AUTHOR]

This study brings forward the results of previously published work of free surface flow simulation around a fast ship model. Experimental measurements and numerical simulations of a fast bare-hull ship model form are now extended to the same ship form with appendices for a wide range of Froude numbers. The governing equations are discretized by means of an unstructured finite volume mesh. The standard k-å turbulence model and Volume of Fluid Method to capture the two phase media are used. The total resistance, due to wave and wake fields of the ship model with appendages and the resistance of the appendages alone are calculated numerically, and compared with the experiments. The experiments and computations were performed for 11 different Froude numbers between 0.103 and 0.322. For Froude numbers up to 0.25, numerical simulations found to be quite in agreement with the experiments. It has been found that appendages increase the total drag mainly by increasing the pressure resistance, and the effect of the appendages becomes more important as the flow speed gets higher. [ABSTRACT FROM AUTHOR]

The Arthropoda, the largest phylum of the Animal Kingdom, have successfully evolved to survive various ecological constraints under a wide range of environmental conditions. Central to this survival are the structural designs developed in their exoskeletons and their raptorial appendages for protection and hunting. One such example, the pistol shrimp, is a shallow-water crustacean that is well-known for its aggressive hunting behavior, using its snapper claw to trigger the nucleation of cavitation bubbles that strike targets. In this study, we conducted a multi-scale structural/nanomechanics relationship study of this biotool to analyze its mechanical response to contact stresses. We found that the pistol shrimp snapper claw, which exhibits the capacity to emit a high-velocity water jet during rapid closure actions, is more brittle than other mineralized biotools, exhibiting accelerated wear damage under contact stresses. However, due to an angular offset between the dactylus and pollex of the snapper claw, the appendage never engages in any mechanical contact during the snapping action. This feature is in stark contrast to that reported in other fast raptorial appendages of crustaceans, notably the mantis shrimp dactyl club, which is designed to shatter close range targets in contact mode and exhibits a superior resistance to contact damage and wear. These findings suggest that adaptation of hunting appendages goes beyond their macroscopic morphology, and that multi-scale structural design concomitantly adapted to function, with enhanced structural complexification for tools that are subjected to more intense contact stresses. Statement of Significance The evolution success of crustaceans is largely due to the diversification of their mineralized exoskeletons and hunting appendages, which exhibit a large palette of morphometric characteristics that have adapted to meet particular functions. We explored the “snapper claw” of the pistol shrimp, which is used to generate cavitation bubbles and strike prey. Our multi-scale structure-property relationship study reveals that the snapper claw is more brittle than other fast raptorial appendages – such as the stomatopod dactyl club – because it is not directly subjected to direct contact forces during action. This study implies that when higher mechanical stresses are needed to meet the function, the internal structure is built of a more complex architecture that allows to mitigate internal structural damage. [ABSTRACT FROM AUTHOR]

Sea spiders form a small, enigmatic group of recent chelicerates, with an unusual bodyplan, oligosegmented larvae and a postembryonic development that is punctuated by many moults. To date, only a few papers examined the anatomical and ultrastructural modifications of the larvae and various instars. Here we traced both internal and external events of the whole postembryonic development in Nymphon brevirostre HODGE 1863 using histology, SEM, TEM and confocal microscopy. During postembryonic development, larvae of this species undergo massive reorganization: spinning apparatus and chelar glands disappear; larval legs redifferentiate; three new segments and the abdomen are formed with their corresponding internal organs and appendages; circulatory and reproductive systems develop anew and the digestive and the nervous systems change dramatically. The body cavity remains schizocoelic throughout development, and no traces of even transitory coeloms were found in any instar. In Nymphon brevirostre , just like in Artemia salina LINNAEUS 1758 the heart arises through differentiation of the already existing schizocoel, and thus the circulatory systems of arthropods and annelids are not homologous. We found that classical chelicerate tagmata, prosoma and opisthosoma, are inapplicable to adult pycnogonids, with the most striking difference being the fate and structure of the seventh appendage-bearing segment. [ABSTRACT FROM AUTHOR]

Abstract: We describe a new archaeostracan phyllocarid from the famous Early Devonian Hunsrück Slate, Germany. Morphological features suggest a new ceratiocaridid species for which we propose the name Ceratiocaris harpago sp. nov. The exceptionally well‐preserved holotype specimen is the most completely known ceratiocaridid with an almost entire set of appendages including biflagellate antenniform antennules, robust uniramous antennae with hook‐like flagellum, thoracopods densely covered with setae and probably six pairs of pleopods. A nectobenthic lifestyle is considered the most probable and the clasper‐like morphology of the antennae suggests the presence of a sexual dimorphism in this taxon, with the holotype specimen being a male individual. [ABSTRACT FROM AUTHOR]

Protocells are objects that mimic one or several functions of biological cells and may be embodied as solid particles, lipid vesicles, or droplets. Our work is based on using decanol droplets in an aqueous solution of sodium decanoate in the presence of salt. A decanol droplet under such conditions bears many qualitative similarities with living cells, such as the ability to move chemotactically, divide and fuse, or change its shape. This article focuses on the description of a shape-changing process induced by the evaporation of water from the decanoate solution. Under these conditions, the droplets perform complex shape changes, whereby the originally round decanol droplets grow into branching patterns and mimic the growth of appendages in bacteria or axon growth of neuronal cells. We report two outcomes: (i) the morphological changes are reversible, and (ii) multiple protocells avoid contact between each other during the morphological transformation. The importance of these morphological changes in the context of artificial life are discussed. [ABSTRACT FROM AUTHOR]

Prokaryotic microbes possess a variety of appendages on their cell surfaces. The most commonly known surface appendages of bacteria include flagella, pili, curli, and spinae. Although archaea have archaella (archaeal flagella) and various types of pili that resemble those in bacteria, cannulae, and hami are unique to archaea. Typically involved in cell motility, flagella, the thickest appendages, are 20-26 nm and 10-14 nm wide in bacteria and archaea, respectively. Bacterial and archaeal pili are distinguished by their thin, short, hair-like structures. Curli appear as coiled and aggregative thin fibers, whereas spinae are tubular structures 50-70 nm in diameter in bacteria. Cannulae are characterized by ∼25 nm-wide tubules that enter periplasmic spaces and connect neighboring archaeal cells. Hami are 1-3 μm in length and similar to barbed grappling hooks for attachment to bacteria. Recent advances in specimen preparation methods and image processing techniques have made cryo-transmission electron microscopy an essential tool for in situ structural analysis of microbes and their extracellular structures. [ABSTRACT FROM AUTHOR]

• The anatomical features of the floral parts contribute to the taxonomic delimitation of the species. • The triads develop from a meristematic mass located in the axil of a bract, this mass is subdivided into three also meristematic portions, a flower and a bract emerge from each of them. • Androecium differentiates centrifugally. • Three types of trichomes and emergences were identified. Bactris is a Neotropical genus of high floristic importance, which needs morphological data to support the construction of a correct infrageneric classification. In this research, the inflorescences and flowers of Bactris acanthocarpoides Barb and B. hirta Rodr. Mart., are morphoanatomically characterised and the floral ontogeny in each of these taxa is presented in order to provide useful biological information that contributes to such classification. The results are analyzed in the context of reproduction and evolution of the palms. To achieve this, we use light and scanning electron microscopy. The distribution of appendages on the prophyll, the development of staminodes in the pistillate flowers of B. acanthocarpoides , the presence of tector trichomes on the sepals of this species, the greater scleromorphism and the presence of papillose exothecium in B. hirta , as well as the location of the vascular bundles in the perianth parts, are characters that allow distinguishing the taxa. The ontogenetic study reveals the acropetal development of the inflorescences, as well as the formation of one subtending bract for each flower of the triad and one for each triad; likewise the sequence of centrifugal development of the stamens and the formation of the gynoecium synascidiate at the base and simplicate at the top. Additionally, the histological arrangement of each floral organ was characterized and all the appendages observed were described. [ABSTRACT FROM AUTHOR]

The Drosophila body comprises a central part, the trunk, and outgrowths of the trunk, the appendages. Much is known about appendage regeneration, but little about the trunk. As the wing imaginal disc contains a trunk component, the notum, and a wing appendage, we have investigated the response to ablation of these two components. We find that, in contrast with the strong regenerative response of the wing, the notum does not regenerate. Nevertheless, the elimination of the wing primordium elicits a proliferative response of notum cells, but they do not regenerate wing; they form a notum duplicate. Conversely, the wing cells cannot regenerate an ablated notum; they overproliferate and generate a hinge overgrowth. These results suggest that trunk and appendages cannot be reprogrammed to generate each other. Our experiments demonstrate that the proliferative response is mediated by JNK signalling from dying cells, but JNK functions differently in the trunk and the appendages, which may explain their distinct regenerative potential. [ABSTRACT FROM AUTHOR]

Appendage anatomy contributes crucial data for understanding the evolution and ecology of Euarthropoda. The Palaeozoic trilobites show a great diversity of exoskeletons in the fossil record. However, soft parts, especially appendages, have only been discovered from a few trilobite species. Here we report extraordinarily preserved appendages in the trilobite species Hongshiyanaspis yiliangensis Zhang & Lin in Zhang et al. 1980 (Redlichiida, Metadoxididae) from a single mudstone layer of the Xiazhuang fossil assemblage within the Hongjingshao Formation (Cambrian Series 2, Stage 3) near Kunming, Yunnan, SW China. The appendages exhibit the common architecture revealed by other trilobites and artiopods by consisting of a pair of uniramous antennae followed by a series of paired homonomous biramous limbs. The antennae in holaspid individuals comprise up to 27 spinous podomeres and their ontogeny occurs by lengthening of the podomeres. The post-antennal biramous limbs are similar to those in other polymerid trilobites and artiopods by having a single-segmented protopodite and an endopodite comprising seven segments, but possess a unique wide tripartite exopodite with long setae. Sophisticated appendage anatomy, including the body–limb junction, fine setae, putative muscle bundles and duct-type tissues, are also revealed. Appendages of trilobites, artiopods and other upper stem-group euarthropods are compared and summarized. The H. yiliangensis appendages highlight the high morphological disparity of exopodites and the conservativeness of endopodites in trilobites and artiopods. This morphological pattern, together with similar body patterning seen in crustaceans but not in chelicerates, supports the mandibulate affinities of trilobites and at least some artiopods. [ABSTRACT FROM PUBLISHER]

The deutocerebral (second) head segment is putatively homologous across Arthropoda, in spite of remarkable disparity of form and function of deutocerebral appendages. In Mandibulata this segment bears a pair of sensory antennae, whereas in Chelicerata the same segment bears a pair of feeding appendages called chelicerae. Part of the evidence for the homology of deutocerebral appendages is the conserved function of homothorax ( hth ), which has been shown to specify antennal or cheliceral fate in the absence of Hox signaling, in both mandibulate and chelicerate exemplars. However, the genetic basis for the morphological disparity of antenna and chelicera is not understood. To test whether downstream targets of hth have diverged in a lineage-specific manner, we examined the evolution of the function and expression of spineless ( ss ), which in two holometabolous insects is known to act as a hth target and distal antennal determinant. Toward expanding phylogenetic representation of gene expression data, here we show that strong expression of ss is observed in developing antennae of a hemimetabolous insect, a centipede, and an amphipod crustacean. By contrast, ss orthologs are not expressed throughout the cheliceral limb buds of spiders or harvestmen during developmental stages when appendage fate is specified. RNA interference-mediated knockdown of ss in Oncopeltus fasciatus , which bears a simple plesiomorphic antenna, resulted in homeotic distal antenna-to-leg transformation, comparable to data from holometabolous insect counterparts. Knockdown of hth in Oncopeltus fasciatus abrogated ss expression, suggesting conservation of upstream regulation. These data suggest that ss may be a flagellar (distal antennal) determinant more broadly, and that this function was acquired at the base of Mandibulata. [ABSTRACT FROM AUTHOR]

A detailed analysis of the maneuvering qualities of a submarine vehicle is carried out by means of a general purpose unsteady RaNSe based CFD solver. In particular, free running maneuvering simulations are performed both at infinite depth and close to the free surface (snorkeling operation) at a reference speed corresponding to Fr = 0.21 ; the analysis is restricted to three degrees of freedom (3DoF) maneuvers in the horizontal plane. The submarine model is equipped with two different control device arrangements, namely a cruciform and a X rudder configuration. The numerical results are presented in a phenomenological style and are partially validated with the experiments for the cruciform rudder configuration. Main finding highlights the superior turning abilities of the X rudder configuration with respect to the cruciform one. Moreover, it has been observed that, for the condition investigated and for both configurations, the stern appendages provide a destabilizing force only in the transient phase, while it acts as a fixed appendage during the steady turning phase. The study focuses also on the effect of grid refinement on both the maneuvering loads and the resulting dynamic response of the model. The analysis revealed that, at least for the present geometry and test, a rather coarse grid (order of millions of grid points) provides a reliable prediction of both the trajectory and kinematic parameters, but a rather inaccurate hydrodynamic loads estimation. [ABSTRACT FROM AUTHOR]