Structural insights into a functional unit from an immunogenic mollusk hemocyanin

Mollusk hemocyanins, among the largest known proteins, are used as immunostimulants in biomedical and clinical applications. The hemocyanin of the Chilean gastropod Concholepas concholepas (CCH) exhibits unique properties, which makes it safe and effective for human immunotherapy, as observed in animal models of bladder cancer and melanoma, and dendritical cell vaccine trials. Despite its potential, the structure and amino acid sequence of CCH remain unknown. This study reports two sequence fragments of CCH, representing three complete functional units (FUs). We also determined the high-resolution (1.5 Å) X-ray crystal structure of an "FU-g type" from the CCHB subunit. This structure enables in-depth analysis of chemical interactions at the copper-binding center and unveils an unusual, truncated N-glycosylation pattern. These features are linked to eliciting more robust immunological responses in animals, offering insights into CCH's enhanced immunostimulatory properties and opening new avenues for its potential applications in biomedical research and therapies.

Novel Strategies for Orofacial Soft Tissue Regeneration

Significance: Orofacial structures are indispensable for speech and eating, and impairment disrupts whole-body health through malnutrition and poor quality of life. However, due to the unique and highly specialized cell populations, tissue architecture, and healing microenvironments, regeneration in this region is challenging and inadequately addressed to date. Recent Advances: With increasing understanding of the nuanced physiology and cellular responses of orofacial soft tissue, novel scaffolds, seeded cells, and bioactive molecules were developed in the past 5 years to specifically target orofacial soft tissue regeneration, particularly for tissues primarily found within the orofacial region such as oral mucosa, taste buds, salivary glands, and masseter muscles. Critical Issues: Due to the tightly packed and complex anatomy, orofacial soft tissue injury commonly implicates multiple tissue types, and thus functional unit reconstruction in the orofacial region is more important than single tissue regeneration. Future Directions: This article reviews the up-to-date knowledge in this highly translational topic, which provides insights into novel biologically inspired and engineered strategies for regenerating orofacial component tissues and functional units.

[Heart Diseases by Professor Dmitry D. Pletnev (for the reprint of D.D. Pletnev's monograph "Heart Diseases", 1936)]

The article presents a brief review of Heart Diseases (1936), the monograph by one of the founders of domestic and world cardiology Dmitry Dmitrievich Pletnev. In the monograph, he summarized his clinical and experimental approach to the issues of heart diseases, addressed several fundamental problems of modern physiology and healthcare, introduced the concept of "functional unit" and "functional unity of the whole body", the concept of the extracardiac genesis of the chest frog, differential diagnosis of left and right ventricle myocardial infarction, semiotics and treatment of chronic heart failure, functional diagnosis of heart arrhythmias. All these approaches and concepts have long been included in the classics of world cardiology.

Functional unit of supergene in female-limited Batesian mimicry of Papilio polytes

Supergenes are sets of genes and genetic elements that are inherited like a single gene and control complex adaptive traits, but their functional roles and units are poorly understood. In Papilio polytes, female-limited Batesian mimicry is thought to be regulated by a ∼130 kb inversion region (highly diversified region: HDR) containing 3 genes, UXT, U3X, and doublesex (dsx) which switches non-mimetic and mimetic types. To determine the functional unit, we here performed electroporation-mediated RNAi analyses (and further Crispr/Cas9 for UXT) of genes within and flanking the HDR in pupal hindwings. We first clarified that non-mimetic dsx-h had a function to form the non-mimetic trait in female and only dsx-H isoform 3 had an important function in the formation of mimetic traits. Next, we found that UXT was involved in making mimetic-type pale-yellow spots and adjacent gene sir2 in making red spots in hindwings, both of which refine more elaborate mimicry. Furthermore, downstream gene networks of dsx, U3X, and UXT screened by RNA sequencing showed that U3X upregulated dsx-H expression and repressed UXT expression. These findings demonstrate that a set of multiple genes, not only inside but also flanking HDR, can function as supergene members, which extends the definition of supergene unit than we considered before. Also, our results indicate that dsx functions as the switching gene and some other genes such as UXT and sir2 within the supergene unit work as the modifier gene.

The anatomy and variation of the coracoid attachment of the subclavius muscle in humans

The functions of the subclavius muscle (SM) are described as stabilization of the sternoclavicular joint (SCJ) and resisting elevation of the lateral end of the clavicle. During systematic cadaveric dissections, we observed additional fibrous structures, previously described as variants of the anatomy, extending from the SM and inserting into the coracoid process (CP). Due to the high incidence of these structures in our dissections, we hypothesized that the attachment at the CP is more common than appreciated and that, as a corollary, the function of the SM was (or has been) more complex than simply depressing the clavicle and generating stability at the SCJ. For our investigation, fifty‐two upper extremities of 26 human cadavers were dissected. The SM was demonstrated from costal to clavicular attachment. We documented additional fibrous structures apparently derived from the SM inserting into the CP. Measurements of the length of the SM, the length of its attachment, and the length of the clavicle were taken in situ, with the specimens supine and the upper extremity in the anatomical position. Variations in the anatomy of the SM and its coracoidal attachment were recorded, and potential correlations were investigated. For documentation purposes photographs and video sequences of passive motion of the shoulder girdle of the specimens were taken. In 49 of the 52 specimens we found additional fibrous structures passing from the SM to the CP. We differentiated three types: (1) a strong cord‐like structure; (2) a small or thin cord‐like structure or structures; and (3) a planar twisted sheet‐like structure. The SM and its extension to the CP appears to contribute to a ‘functional scapular suspension system’ together with the other muscles enveloped by the clavipectoral fascia (pectoralis minor, coracobrachialis and the short head of the biceps brachii). This system assists in the control of the position of the scapula in relation to the thorax, particularly in elevated positions of the upper extremity. We speculate that the differentiation of the fibrous structure depends on the functional demands of the individual.

Level of Evidence: Basic science study.

Hypothalamic Contribution to Pituitary Functions Is Recapitulated In Vitro Using 3D-Cultured Human iPS Cells

The pituitary is a major hormone center that secretes systemic hormones responding to hypothalamus-derived-releasing hormones. Previously, we reported the independent pituitary induction and hypothalamic differentiation of human embryonic stem cells (ESCs). Here, a functional hypothalamic-pituitary unit is generated using human induced pluripotent stem (iPS) cells in vitro. The adrenocorticotropic hormone (ACTH) secretion capacity of the induced pituitary reached a comparable level to that of adult mouse pituitary because of the simultaneous maturation with hypothalamic neurons within the same aggregates. Corticotropin-releasing hormone (CRH) from the hypothalamic area regulates ACTH cells similarly to our hypothalamic-pituitary axis. Our induced hypothalamic-pituitary units respond to environmental hypoglycemic condition in vitro, which mimics a life-threatening situation in vivo, through the CRH-ACTH pathway, and succeed in increasing ACTH secretion. Thus, we generated powerful hybrid organoids by recapitulating hypothalamic-pituitary development, showing autonomous maturation on the basis of interactions between developing tissues.

Relative emissions intensity of dairy production systems: employing different functional units in life-cycle assessment

This study aimed to assess the merit and suitability of individual functional units (FU) in expressing greenhouse gas emissions intensity in different dairy production systems. An FU provides a clearly defined and measurable reference to which input and output data are normalised. This enables the results from life-cycle assessment (LCA) of different systems to be treated as functionally equivalent. Although the methodological framework of LCA has been standardised, selection of an appropriate FU remains ultimately at the discretion of the individual study. The aim of the present analysis was to examine the effect of different FU on the emissions intensities of different dairy production systems. Analysis was based on 7 years of data (2004 to 2010) from four Holstein-Friesian dairy systems at Scotland’s Rural College’s long-term genetic and management systems project, the Langhill herd. Implementation of LCA accounted for the environmental impacts of the whole-farm systems and their production of milk from ‘cradle to farm gate’. Emissions intensity was determined as kilograms of carbon dioxide equivalents referenced to six FU: UK livestock units, energy-corrected milk yield, total combined milk solids yield, on-farm land used for production, total combined on- and off-farm land used for production, and the proposed new FU–energy-corrected milk yield per hectare of total land used. Energy-corrected milk was the FU most effective for reflecting differences between the systems. Functional unit that incorporated a land-related aspect did not find difference between systems which were managed under the same forage regime, despite their comprising different genetic lines. Employing on-farm land as the FU favoured grazing systems. The proposed dual FU combining both productivity and land use did not differentiate between emissions intensity of systems as effectively as the productivity-based units. However, this dual unit displayed potential to quantify in a simple way the positive or negative outcome of trade-offs between land and production efficiencies, in which improvement in emissions intensity using one FU may be accompanied by deterioration using another FU. The perceived environmental efficiencies of different dairy production systems in terms of their emissions intensities were susceptible to change based upon the FU employed, and hence the FU used in any study needs to be taken into account in the interpretation of results.

An approach to including protein quality when assessing the net contribution of livestock to human food supply

The production of protein from animal sources is often criticized because of the low efficiency of converting plant protein from feeds into protein in the animal products. However, this critique does not consider the fact that large portions of the plant-based proteins fed to animals may be human-inedible and that the quality of animal proteins is usually superior as compared with plant proteins. The aim of the present study was therefore to assess changes in protein quality in the course of the transformation of potentially human-edible plant proteins into animal products via livestock production; data from 30 Austrian dairy farms were used as a case study. A second aim was to develop an approach for combining these changes with quantitative aspects (e.g. with the human-edible feed conversion efficiency (heFCE), defined as kilogram protein in the animal product divided by kilogram potentially human-edible protein in the feeds). Protein quality of potentially human-edible inputs and outputs was assessed using the protein digestibility-corrected amino acid score and the digestible indispensable amino acid score, two methods proposed by the Food and Agriculture Organization of the United Nations to describe the nutritional value of proteins for humans. Depending on the method used, protein scores were between 1.40 and 1.87 times higher for the animal products than for the potentially human-edible plant protein input on a barn-gate level (=protein quality ratio (PQR)). Combining the PQR of 1.87 with the heFCE for the same farms resulted in heFCE×PQR of 2.15. Thus, considering both quantity and quality, the value of the proteins in the animal products for human consumption (in this case in milk and beef) is 2.15 times higher than that of proteins in the potentially human-edible plant protein inputs. The results of this study emphasize the necessity of including protein quality changes resulting from the transformation of plant proteins to animal proteins when evaluating the net contribution of livestock to the human food supply. Furthermore, these differences in protein quality might also need to be considered when choosing a functional unit for the assessment of environmental impacts of the production of different proteins.

Evolution of molluscan hemocyanin structures

Hemocyanin transports oxygen in the hemolymph of many molluscs and arthropods and is therefore a central physiological factor in these animals. Molluscan hemocyanin molecules are oligomers composed of many protein subunits that in turn encompass subsets of distinct functional units. The structure and evolution of molluscan hemocyanin have been studied for decades, but it required the recent progress in DNA sequencing, X-ray crystallography and 3D electron microscopy to produce a detailed view of their structure and evolution. The basic quaternary structure is a cylindrical decamer 35nm in diameter, consisting of wall and collar (typically at one end of the cylinder). Depending on the animal species, decamers, didecamers and multidecamers occur in the hemolymph. Whereas the wall architecture of the decamer seems to be invariant, four different types of collar have been identified in different molluscan taxa. Correspondingly, there exist four subunit types that differ in their collar functional units and range from 350 to 550kDa. Thus, molluscan hemocyanin subunits are among the largest polypeptides in nature. In this report, recent 3D reconstructions are used to explain and visualize the different functional units, subunits and quaternary structures of molluscan hemocyanins. Moreover, on the basis of DNA analyses and structural considerations, their possible evolution is traced. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.

3D domain swapping: as domains continue to swap

Three-dimensional (3D) domain swapping creates a bond between two or more protein molecules as they exchange their identical domains. Since the term '3D domain swapping' was first used to describe the dimeric structure of diphtheria toxin, the database of domain-swapped proteins has greatly expanded. Analyses of the now about 40 structurally characterized cases of domain-swapped proteins reveal that most swapped domains are at either the N or C terminus and that the swapped domains are diverse in their primary and secondary structures. In addition to tabulating domain-swapped proteins, we describe in detail several examples of 3D domain swapping which show the swapping of more than one domain in a protein, the structural evidence for 3D domain swapping in amyloid proteins, and the flexibility of hinge loops. We also discuss the physiological relevance of 3D domain swapping and a possible mechanism for 3D domain swapping. The present state of knowledge leads us to suggest that 3D domain swapping can occur under appropriate conditions in any protein with an unconstrained terminus. As domains continue to swap, this review attempts not only a summary of the known domain-swapped proteins, but also a framework for understanding future findings of 3D domain swapping.