Physiology Of Organisms Research Articles

Constitutive and activated toxigenic activity ofHalomicronema metazoicum(Cyanoprokaryota, Cyanophyta)

AbstractPhormidium‐like cyanobacteria produce a variety of biologically active molecules. We isolated a free‐living strain ofHalomicronema metazoicum, previously known uniquely as a symbiont of marine sponges, and demonstrated that its spent medium was toxic for various protozoans and fish parasites. However, we still ignore if its mats contain constitutive or activated defences influencing the physiology of other organisms, with potential influences on organisms that share the same environment. The goal of this study is to clarify ifPhormidium‐like cyanobacteria accumulate toxic bioactive molecules in the colony tissues, for example for anti‐grazing purposes, or if they constitutively secrete them in the medium, with a potential allelopathic function. To address this hypothesis, the toxigenic power of cyanobacterial spent medium and of disintegrated cells (to simulate lysis) was assayed using standard toxicity‐tests on nauplii of the brine shrimpArtemia salina. Toxigenic effects were triggered by the spent culture medium, but the homogenates (disintegrated cyanobacteria cells) did not show any acute toxicity. In addition, chronic toxicity tests of the spent medium demonstrated a reduced but still present toxigenic effect, with an inverse correlation between toxicity and medium dilution. The present research contributes to the understanding of cyanobacteria chemical‐ecology and shows that they may play fundamental ecological roles, influencing the survival and the blooms of various co‐habiting species by constitutively releasing toxic exudates. Since the bioactive compounds produced byH. metazoicumare stable in water, and considering the bioactivity of exudates on invertebrates' physiology, our results might be exploited for the development of novel biotechnologies in the fields of aquaculture, ecological conservation and medicine, due to the potential antitumoral and anti‐parasitic activity demonstrated in strictly related species.

Tailoring Cardiac Synthetic Transcriptional Modulation Towards Precision Medicine.

Molecular and genetic differences between individual cells within tissues underlie cellular heterogeneities defining organ physiology and function in homeostasis as well as in disease states. Transcriptional control of endogenous gene expression has been intensively studied for decades. Thanks to a fast-developing field of single cell genomics, we are facing an unprecedented leap in information available pertaining organ biology offering a comprehensive overview. The single-cell technologies that arose aided in resolving the precise cellular composition of many organ systems in the past years. Importantly, when applied to diseased tissues, the novel approaches have been immensely improving our understanding of the underlying pathophysiology of common human diseases. With this information, precise prediction of regulatory elements controlling gene expression upon perturbations in a given cell type or a specific context will be realistic. Simultaneously, the technological advances in CRISPR-mediated regulation of gene transcription as well as their application in the context of epigenome modulation, have opened up novel avenues for targeted therapy and personalized medicine. Here, we discuss the fast-paced advancements during the recent years and the applications thereof in the context of cardiac biology and common cardiac disease. The combination of single cell technologies and the deep knowledge of fundamental biology of the diseased heart together with the CRISPR-mediated modulation of gene regulatory networks will be instrumental in tailoring the right strategies for personalized and precision medicine in the near future. In this review, we provide a brief overview of how single cell transcriptomics has advanced our knowledge and paved the way for emerging CRISPR/Cas9-technologies in clinical applications in cardiac biomedicine.

Lipid Metabolism in Cancer: The Role of Acylglycerolphosphate Acyltransferases (AGPATs).

Simple SummaryRapidly proliferating cancer cells reprogram lipid metabolism to keep the balance between fatty acid uptake, synthesis, consumption, and storage as triacylglycerides (TAG). Acylglycerolphosphate acyltransferases (AGPATs)/lysophosphatidic acid acyltransferases (LPAATs) are a family of enzymes that catalyze the synthesis of phosphatidic acid (PA), an intermediate in TAG synthesis, a signaling molecule, and a precursor of phospholipids. Importantly, the expression of AGPATs has been linked to diverse physiological and pathological phenotypes, including cancer. In this review, we present an overview of lipid metabolism reprogramming in cancer cells and give insight into the expression of AGPAT isoforms as well as their association with cancers, parameters of tumor biology, patient classification, and prognosis.Altered lipid metabolism is an emerging hallmark of aggressive tumors, as rapidly proliferating cancer cells reprogram fatty acid (FA) uptake, synthesis, storage, and usage to meet their increased energy demands. Central to these adaptive changes, is the conversion of excess FA to neutral triacylglycerides (TAG) and their storage in lipid droplets (LDs). Acylglycerolphosphate acyltransferases (AGPATs), also known as lysophosphatidic acid acyltransferases (LPAATs), are a family of five enzymes that catalyze the conversion of lysophosphatidic acid (LPA) to phosphatidic acid (PA), the second step of the TAG biosynthesis pathway. PA, apart from its role as an intermediate in TAG synthesis, is also a precursor of glycerophospholipids and a cell signaling molecule. Although the different AGPAT isoforms catalyze the same reaction, they appear to have unique non-overlapping roles possibly determined by their distinct tissue expression and substrate specificity. This is best exemplified by the role of AGPAT2 in the development of type 1 congenital generalized lipodystrophy (CGL) and is also manifested by recent studies highlighting the involvement of AGPATs in the physiology and pathology of various tissues and organs. Importantly, AGPAT isoform expression has been shown to enhance proliferation and chemoresistance of cancer cells and correlates with increased risk of tumor development or aggressive phenotypes of several types of tumors.

The Clock Takes Shape-24h Dynamics in Genome Topology.

Circadian rhythms orchestrate organismal physiology and behavior in order to anticipate daily changes in the environment. Virtually all cells have an internal rhythm that is synchronized every day by Zeitgebers (environmental cues). The synchrony between clocks within the animal enables the fitness and the health of organisms. Conversely, disruption of rhythms is linked to a variety of disorders: aging, cancer, metabolic diseases, and psychological disorders among others. At the cellular level, mammalian circadian rhythms are built on several layers of complexity. The transcriptional-translational feedback loop (TTFL) was the first to be described in the 90s. Thereafter oscillations in epigenetic marks highlighted the role of chromatin state in organizing the TTFL. More recently, studies on the 3D organization of the genome suggest that genome topology could be yet another layer of control on cellular circadian rhythms. The dynamic nature of genome topology over a solar day implies that the 3D mammalian genome has to be considered in the fourth dimension-in time. Whether oscillations in genome topology are a consequence of 24 h gene-expression or a driver of transcriptional cycles remains an open question. All said and done, circadian clock-gated phenomena such as gene expression, DNA damage response, cell metabolism and animal behavior—go hand in hand with 24 h rhythms in genome topology.

The role of food odor in invertebrate foraging.

Foraging for food is an integral part of animal survival. In small insects and invertebrates, multisensory information and optimized locomotion strategies are used to effectively forage in patchy and complex environments. Here, the importance of olfactory cues for effective invertebrate foraging is discussed in detail. We review how odors are used by foragers to move toward a likely food source and the recent models that describe this sensory-driven behavior. We argue that smell serves a second function by priming an organism for the efficient exploitation of food. By appraising food odors, invertebrates can establish preferences and better adapt to their ecological niches, thereby promoting survival. The smell of food pre-prepares the gastrointestinal system and primes feeding motor programs for more effective ingestion as well. Optimizing resource utilization affects longevity and reproduction as a result, leading to drastic changes in survival. We propose that models of foraging behavior should include odor priming, and illustrate this with a simple toy model based on the marginal value theorem. Lastly, we discuss the novel techniques and assays in invertebrate research that could investigate the interactions between odor sensing and food intake. Overall, the sense of smell is indispensable for efficient foraging and influences not only locomotion, but also organismal physiology, which should be reflected in behavioral modeling.

The compartmentalised nature of neuronal mitophagy: molecular insights and implications.

The maintenance of a healthy mitochondrial network and the ability to adjust organelle population in response to internal or external stimuli are essential for the function and the survival of eukaryotic cells. Over the last two decades several studies have demonstrated the paramount importance of mitophagy, a selective form of autophagy that removes damaged and/or superfluous organelles, in organismal physiology. Post-mitotic neuronal cells are particularly vulnerable to mitochondrial damage, and mitophagy impairment has emerged as a causative factor in multiple neurodegenerative pathologies, including Alzheimer's disease and Parkinson's disease among others. Although mitochondrial turnover is a multifaceted process, neurons have to tackle additional complications, arising from their pronounced bioenergetic demands and their unique architecture and cellular polarisation that render the degradation of distal organelles challenging. Mounting evidence indicates that despite the functional conservation of mitophagy pathways, the unique features of neuronal physiology have led to the adaptation of compartmentalised solutions, which serve to ensure seamless mitochondrial removal in every part of the cell. In this review, we summarise the current knowledge concerning the molecular mechanisms that mediate mitophagy compartmentalisation and discuss their implications in various human pathologies.

Becoming aware of γδ T cells.

The discovery that B cells and αβ T cells exist was predictable: These cells gave themselves away through their products and biological effects. In contrast, there was no reason to anticipate the existence of γδ T cells. Even the accidental discovery of a novel TCR-like gene (later named γ) that did not encode TCR α or β proteins did not immediately change this. TCR-like γ had no obvious function, and its early expression in the thymus encouraged speculation about a possible role in αβ T cell development. However, the identification of human PBL-derived cell-lines which expressed CD3 in complex with the TCR-like γ protein, but not the αβ TCR, first indicated that a second T cell-type might exist, and the TCR-like γ chain was observed to co-precipitate with another protein. Amid speculation about a possible second TCR, this potential dimeric partner was named δ. To determine if the δ protein was indeed TCR-like, we undertook to sequence it. Meanwhile, a fourth TCR-like gene was discovered and provisionally named x. TCR-like x had revealed itself through genomic rearrangements early in T cell development, and was an attractive candidate for the gene encoding δ. The observation that δ protein sequences matched the predicted amino acid sequences encoded by the x gene, as well as serological cross-reactivity, confirmed that the TCR-like x gene indeed encoded the δ protein. Thus, the γδ heterodimer was established as a second TCR, and the cells that express it (the γδ T cells) consequently represented a third lymphocyte-population with the potential of recognizing diverse antigens. Soon, it became clear that γδ T cells are widely distributed and conserved among the vertebrate species, implying biological importance. Consistently, early functional studies revealed their roles in host resistance to pathogens, tissue repair, immune regulation, metabolism, organ physiology and more. Albeit discovered late, γδ T cells have repeatedly proven to play a distinct and often critical immunological role, and now generate much interest.

Effects of temperature and pH on the growth, calcification, and biomechanics of two species of articulated coralline algae

Ocean warming and acidification are predicted to impact the physiology of marine organisms, especially marine calcifiers that must deposit calcium carbonate and resist dissolution. Of particular concern are articulated coralline algae, which must maintain both calcified segments (intergenicula) and uncalcified joints (genicula) in order to thrive along wave-swept rocky coastlines. We examined the effect of pH and temperature, both individually and in combination, on the growth, calcification, and biomechanical properties of 2 species of articulated coralline algae, Corallina vancouveriensis and Calliarthron tuberculosum, common on wave-exposed shores in the NE Pacific. Increased temperature and reduced pH were found to reduce growth rates in both species (30-89% lower) but had little influence on the amount of intergenicular calcium carbonate or on the genicular biomechanical properties of these species. Results suggest that although growth rates may decline, these 2 coralline species will maintain the integrity of their tissues and continue to persist under future climate stress.

Environmental heterogeneity drives the distribution of copepods (Crustacea: Copepoda) in the Amazon, Araguaia, Pantanal, and Upper Paraná floodplains.

Environmental heterogeneity influences the physiology and behavior of organisms, leading to alterations in populations, communities, and ecosystems. This study was designed to evaluate the effect of the spatial and temporal limnological heterogeneity on the distribution of copepods in the Amazon River floodplain, Araguaia River floodplain, Pantanal floodplain, and Upper Paraná River floodplain. We performed dispersion homogeneity tests (PERMIDISP) to analyze the limnological heterogeneity, a Generalized Linear Mixed Model (GLMM) to test the relationship between limnological heterogeneity and species distribution, and a Canonical Correspondence Analysis (CCA) to analyze which limnological variables explain the variation in the community composition. In our study, we observed higher environmental heterogeneity during dry periods, especially in the Amazon floodplain. The Amazon showed the highest species richness (the total number of species that occurred in each floodplain), with endemic species, also the highest abundance of individuals, especially during dry periods, which was possibly due to the biogeography, the size of the basin, and the heterogeneity of the environments. The Pantanal presented the second highest species richness and showed the highest species richness and abundance of individuals during rainy periods. The distribution of copepods was highly correlated with environmental heterogeneity. The species were mainly related to temperature, nutrients, and depth.

Fruity, sticky, stinky, spicy, bitter, addictive, and deadly: evolutionary signatures of metabolic complexity in the Solanaceae.

Covering: 2000-2022Plants collectively synthesize a huge repertoire of metabolites. General metabolites, also referred to as primary metabolites, are conserved across the plant kingdom and are required for processes essential to growth and development. These include amino acids, sugars, lipids, and organic acids. In contrast, specialized metabolites, historically termed secondary metabolites, are structurally diverse, exhibit lineage-specific distribution and provide selective advantage to host species to facilitate reproduction and environmental adaptation. Due to their potent bioactivities, plant specialized metabolites attract considerable attention for use as flavorings, fragrances, pharmaceuticals, and bio-pesticides. The Solanaceae (Nightshade family) consists of approximately 2700 species and includes crops of significant economic, cultural, and scientific importance: these include potato, tomato, pepper, eggplant, tobacco, and petunia. The Solanaceae has emerged as a model family for studying the biochemical evolution of plant specialized metabolism and multiple examples exist of lineage-specific metabolites that influence the senses and physiology of commensal and harmful organisms, including humans. These include, alcohols, phenylpropanoids, and carotenoids that contribute to fruit aroma and color in tomato (fruity), glandular trichome-derived terpenoids and acylsugars that contribute to plant defense (stinky & sticky, respectively), capsaicinoids in chilli-peppers that influence seed dispersal (spicy), and steroidal glycoalkaloids (bitter) from Solanum, nicotine (addictive) from tobacco, as well as tropane alkaloids (deadly) from Deadly Nightshade that deter herbivory. Advances in genomics and metabolomics, coupled with the adoption of comparative phylogenetic approaches, resulted in deeper knowledge of the biosynthesis and evolution of these metabolites. This review highlights recent progress in this area and outlines opportunities for - and challenges of-developing a more comprehensive understanding of Solanaceae metabolism.

Bone adaptation to mechanical loading in mice is affected by circadian rhythms.

Physical forces are critical for successful function of many organs including bone. Interestingly, the timing of exercise during the day alters physiology and gene expression in many organs due to circadian rhythms. Circadian clocks in tissues, such as bone, express circadian clock genes that target tissue-specific genes, resulting in tissue-specific rhythmic gene expression (clock-controlled genes). We hypothesized that the adaptive response of bone to mechanical loading is regulated by circadian rhythms. First, mice were sham loaded and sacrificed 8h later, which amounted to tissues being collected at zeitgeber time (ZT)2, 6, 10, 14, 18, and 22. Cortical bone of the tibiae collected from these mice displayed diurnal expression of core clock genes and key osteocyte and osteoblast-related genes, such as the Wnt-signaling inhibitors Sost and Dkk1, indicating these are clock-controlled genes. Serum bone turnover markers did not display rhythmicity. Second, mice underwent a single bout of in vivo loading at either ZT2 or ZT14 and were sacrificed 1, 8, or 24h after loading. Loading at ZT2 resulted in Sost upregulation, while loading at ZT14 led to Sost and Dkk1 downregulation. Third, mice underwent daily in vivo tibial loading over 2weeks administered either in the morning, (ZT2, resting phase) or evening (ZT14, active phase). In vivo microCT was performed at days 0, 5, 10, and 15 and conventional histomorphometry was performed at day 15. All outcome measures indicated a robust response to loading, but only microCT-based time-lapse morphometry showed that loading at ZT14 resulted in a greater endocortical bone formation response compared to mice loaded at ZT2. The decreased Sost and Dkk1 expression coincident with the modest, but significant time-of-day specific increase in adaptive bone formation, suggests that circadian clocks influence bone mechanoresponse.

Byssal thread attachment and growth are not correlated across gradients of temperature and food availability for two congeneric mussel species

Anthropogenic warming and natural climate variability affect global patterns of seawater temperature and marine primary productivity and affect organism survival, growth, and physiology. Mussels are ecosystem engineers that utilize byssal thread structures to attach to hard substrate, a strategy key to survival in wave-swept rocky shore environments. Byssal thread production varies according to season and environmental conditions, and temperature and food availability may influence the production of these structures by affecting energy limitation. Mytilus trossulus and M. galloprovincialis are congeneric mussel species in the Northeast Pacific with cold- and warm-adapted thermal tolerances, respectively. First, we hypothesized that temperature has opposing effects on growth rates of the 2 species. Second, we hypothesized that either (1) byssal thread production is positively correlated with growth rate (the ‘production’ hypothesis), or (2) there is a trade-off between growth and byssal thread production, and resources are allocated first to byssal thread production rather than growth. Under this ‘trade-off’ hypothesis, we predicted no relationship between growth rate and byssal thread production. We manipulated seawater temperature and food availability and quantified mussel performance in terms of survival, growth, and byssus attachment. Across all treatment combinations, we found that M. galloprovincialis had positive shell and tissue growth and M. trossulus had minimal shell growth and a loss in tissue mass. Temperature had opposing effects on each species; temperature increased shell growth of M. galloprovincialis but increased tissue loss of M. trossulus. Temperature did not affect byssal thread production, and there was no significant relationship between byssal thread quality or quantity and shell or tissue growth across the temperature and food gradient for either species. Our results suggest that energy allocation is prioritized towards byssal thread production over growth.

Disrupted Circadian Control of Hormonal Rhythms and Anticipatory Thirst by Dim Light at Night.

Our study addresses underlying mechanisms of disruption of the circadian timing system by low-intensity artificial light at night (ALAN), which is a growing global problem, associated with serious health consequences. Rats were exposed to low-intensity (∼2 lx) ALAN for 2 weeks. Using in situ hybridization, we assessed 24-h profiles of clock and clock-controlled genes in the suprachiasmatic nuclei (SCN) and other hypothalamic regions, which receive input from the master clock. Moreover, we measured the daily rhythms of hormones within the main neuroendocrine axes as well as the detailed daily pattern of feeding and drinking behavior in metabolic cages. ALAN strongly suppressed the molecular clockwork in the SCN, as indicated by the suppressed rhythmicity in the clock (Per1, Per2, and Nr1d1) and clock output (arginine vasopressin) genes. ALAN disturbed rhythmic Per1 expression in the paraventricular and dorsomedial hypothalamic nuclei, which convey the circadian signals from the master clock to endocrine and behavioral rhythms. Disruption of hormonal output pathways was manifested by the suppressed and phase-advanced corticosterone rhythm and lost daily variations in plasma melatonin, testosterone, and vasopressin. Importantly, ALAN altered the daily profile in food and water intake and eliminated the clock-controlled surge of drinking 2 h prior to the onset of the rest period, indicating disturbed circadian control of anticipatory thirst and fluid balance during sleep. Our findings highlight compromised time-keeping function of the central clock and multiple circadian outputs, through which ALAN disturbs the temporal organization of physiology and behavior.

Unveiling Forkhead-mediated regulation of yeast cell cycle and metabolic networks

Transcription factors are regulators of the cell’s genomic landscape. By switching single genes or entire molecular pathways on or off, transcription factors modulate the precise timing of their activation. The Forkhead (Fkh) transcription factors are evolutionarily conserved to regulate organismal physiology and cell division. In addition to molecular biology and biochemical efforts, genome-wide studies have been conducted to characterize the genomic landscape potentially regulated by Forkheads in eukaryotes. Here, we discuss and interpret findings reported in six genome-wide Chromatin ImmunoPrecipitation (ChIP) studies, with a particular focus on ChIP-chip and ChIP-exo. We highlight their power and challenges to address Forkhead-mediated regulation of the cellular landscape in budding yeast. Expression changes of the targets identified in the binding assays are investigated by taking expression data for Forkhead deletion and overexpression into account. Forkheads are revealed as regulators of the metabolic network through which cell cycle dynamics may be temporally coordinated further, in addition to their well-known role as regulators of the gene cluster responsible for cell division.

Microfluidics in vascular biology research: a critical review for engineers, biologists, and clinicians.

Neovascularization, the formation of new blood vessels, has received much research attention due to its implications for physiological processes and diseases. Most studies using traditional in vitro and in vivo platforms find challenges in recapitulating key cellular and mechanical cues of the neovascularization processes. Microfluidic in vitro models have been presented as an alternative to these limitations due to their capacity to leverage microscale physics to control cell organization and integrate biochemical and mechanical cues, such as shear stress, cell-cell interactions, or nutrient gradients, making them an ideal option for recapitulating organ physiology. Much has been written about the use of microfluidics in vascular biology models from an engineering perspective. However, a review introducing the different models, components and progress for new potential adopters of these technologies was absent in the literature. Therefore, this paper aims to approach the use of microfluidic technologies in vascular biology from a perspective of biological hallmarks to be studied and written for a wide audience ranging from clinicians to engineers. Here we review applications of microfluidics in vascular biology research, starting with design considerations and fabrication techniques. After that, we review the state of the art in recapitulating angiogenesis and vasculogenesis, according to the hallmarks recapitulated and complexity of the models. Finally, we discuss emerging research areas in neovascularization, such as drug discovery, and potential future directions.

Cultivating human tissues and organs over lab-on-a-chip models: Recent progress and applications.

In vivo models are indispensable for preclinical studies for various human disease modeling and drug screening, however, face several obstacles such as animal model species differences and ethical clearance. Additionally, it is difficult to accurately predict the organ interaction, drug efficacy, and toxicity using conventional in vitro two-dimensional (2D) cell culture models. The microfluidic-based systems provide excellent opportunity to recapitulate the human organ/tissue functions under in vitro conditions. The organ/tissue-on-chip models are one of best emerging technologies that offer functional organs/tissues on a microfluidic chip. This technology has potential to noninvasively study the organ physiology, tissue development, and diseases etymology. This chapter comprises the benifits of 2D and three-dimensional (3D) in vitro cultures as well as highlights the importance of microfluidic-based lab-on-a-chip technique. The development of different organs/tissues-on-chip models and their biomedical application in various diseases such as cardiovascular diseases, neurodegenerative diseases, respiratory-based diseases, cancers, liver and kidney diseases, etc., have also been discussed.

Serotonergic Paracrine Targets in the Intestinal Mucosa.

Serotonin functions as a neurotransmitter in the enteric nervous system. Aside from its neurotransmitter role, serotonin also is a paracrine mediatorial signal in the digestive tract. It is a major paracrine signaling molecule in the integrated physiology of several classes of cells in the intestinal mucosa. Paracrine action can be initiation or suppression of activity in populations of cells that make up divergent phenotypic classes. This underlies phenotypic plasticity in single classes and links single classes to other neighboring phenotypic classes, thereby forming a single and higher-order organization in which different categories of function are integrated to work in harmony as a single homeostatic entity at higher levels of physiological organization. Phenotypic classes of cells that are linked by serotonergic paracrine signaling at upper levels of functional organization in the small intestine are (1) enterochromaffin cells; (2) enteric mast cells; (3) spinal sensory afferents; (4) sympathetic postganglionic neurons; (5) enteric neurons.

David Clark Taylor, Part 2

David Clark Taylor, Part 2 Kimberly Broadwater (bio) PROVENANCE prov·e·nance (prǒv´ ə nəns) n. Place of origin, source. [Lat. Provenire, to originate.] [A continuation of an excerpt from Taylor's book, The Psychology of Singing: A Rational Method of Voice Culture Based on a Scientific Analysis of All Systems, Ancient and Modern (The Macmillan Company, 1908).] One of the most mysterious facts in the history of Voice Culture is the utter disappearance of the old Italian method. This has occurred in spite of the earnest efforts of vocal teachers to preserve the old traditions. If the conclusions drawn in the preceding chapter are justified, the old method consisted of a system of teaching singing by imitation. Assuming this to be true, there should now be no difficulty in accounting for the disappearance of the imitative method by tracing the development of the mechanical idea. Imitative Voice Culture was purely empirical in the ordinary meaning of this word. The old masters did not knowingly base their instruction on any set of principles. They simply taught as their instincts prompted them. There can now be no doubt that the old masters were fully justified in their empiricism. They taught singing as Nature intends it to be taught. But the old masters were not aware of the scientific soundness of their position. So soon as the correctness of empirical teaching was questioned they abandoned it without an attempt at defense. As a system of Voice Culture, the old method occupied a weak strategic position. With absolute right on its side, it still had no power of resistance against hostile influences. This does not imply that the old masters were ignorant men. On the contrary, the intellectual standard of the vocal profession seems to have been fully as high two hundred years ago as to-day. Even famous composers and musical theorists did not disdain to teach singing. But this very fact, the generally high culture of the old masters, was an important factor in the weakness of the old method against attack. The most intelligent masters were the ones most likely to abandon the empirical system in favor of supposedly scientific and precise methods of instruction. The hostile influence to which the old Italian method succumbed was the idea of mechanical vocal management. This idea entered almost imperceptibly into the minds of vocal teachers in the guise of a scientific theory of Voice Culture. A short historical sketch will bring this fact out clearly. From the founding of the art of Voice Culture, about 1600, up to 1741, no vocalist seems to have paid any attention to the anatomy or muscular movements of the vocal organs. In 1741 a French physician, Ferrein, presented to [End Page 395] the Academy of Sciences a treatise on the anatomy of the vocal organs, entitled "De la Formation de la Voix de l'Homme." This treatise was published in the same year, and it seems to have attracted at once the attention of the most enlightened masters of singing. That Ferrein was the first to call the attention of vocalists to the mechanical features of tone-production is strongly indicated in the German translation of Tosi's "Observations." In the original Italian edition, 1723, and the English translation, 1742, there is absolutely no mention of the anatomy or physiology of the vocal organs. But in preparing the German edition, published in 1757, the translator, J. F. Agricola, inserted a description of the vocal organs which he credited directly to Ferrein. Mancini followed Agricola's example, and included in this "Riflessioni" (1776) a brief description of the vocal organs. But Mancini made no attempt to apply this description in formulating a system of instruction. He recommends the parents of a prospective singer to ascertain, by a physician's examination, that the child's vocal organs are normal and in good health. He also gives one mechanical rule, so obvious as to seem rather quaint. "Every singer must place his mouth in a natural smiling position, that is, with the upper teeth perpendicularly and moderately removed from the lower." Beyond this Mancini says not a word of mechanical vocal management. There is no mention...

On predicting particle capture rates in aquatic ecosystems.

Recent advances in understanding the capture of moving suspended particles in aquatic ecosystems have opened up new possibilities for predicting rates of suspension feeding, larval settlement, seagrass pollination and sediment removal. Drawing on results from both highly-resolved computational fluid dynamics (CFD) simulations and existing experimental data, we quantify the controlling influence of flow velocity, particle size and collector size on rates of contact between suspended particles and biological collectors over the parameter space characterising a diverse range of aquatic ecosystems. As distinct from assumptions in previous modeling studies, the functional relationships describing capture are highly variable. Contact rates can vary in opposing directions in response to changes in collector size, an organism’s size, the size of particles being intercepted (related to diet in the case of suspension feeders), and the flow strength. Contact rates shift from decreasing to increasing with collector diameter when particles become relatively large and there is vortex shedding in the collector wake. And in some ranges of the ecologically relevant parameter space, contact rates do not increase strongly with velocity or particle size. The understanding of these complex dependencies allows us to reformulate some hypotheses of selection pressure on the physiology and ecology of aquatic organisms. We discuss the benefits and limitations of CFD tools in predicting rates of particle capture in aquatic ecosystems. Finally, across the complete parameter space relevant to real aquatic ecosystems, all quantitative estimates of particle capture from our model are provided here.

Novel microarchitecture of human endometrial glands: implications in endometrial regeneration and pathologies.

BACKGROUNDHuman endometrium remains a poorly understood tissue of the female reproductive tract. The superficial endometrial functionalis, the site of embryo implantation, is repeatedly shed with menstruation, and the stem cell-rich deeper basalis is postulated to be responsible for the regeneration of the functionalis. Two recent manuscripts have demonstrated the 3D architecture of endometrial glands. These manuscripts have challenged and replaced the prevailing concept that these glands end in blind pouches in the basalis layer that contain stem cells in crypts, as in the intestinal mucosa, providing a new paradigm for endometrial glandular anatomy. This necessitates re-evaluation of the available evidence on human endometrial regeneration in both health and disease in the context of this previously unknown endometrial glandular arrangement.OBJECTIVE AND RATIONALEThe aim of this review is to determine if the recently discovered glandular arrangement provides plausible explanations for previously unanswered questions related to human endometrial biology. Specifically, it will focus on re-appraising the theories related to endometrial regeneration, location of stem/progenitor cells and endometrial pathologies in the context of this recently unravelled endometrial glandular organization.SEARCH METHODSAn extensive literature search was conducted from inception to April 2021 using multiple databases, including PubMed/Web of Science/EMBASE/Scopus, to select studies using keywords applied to endometrial glandular anatomy and regeneration, and the references included in selected publications were also screened. All relevant publications were included.OUTCOMESThe human endometrial glands have a unique and complex architecture; branched basalis glands proceed in a horizontal course adjacent to the myometrium, as opposed to the non-branching, vertically coiled functionalis glands, which run parallel to each other as is observed in intestinal crypts. This complex network of mycelium-like, interconnected basalis glands is demonstrated to contain endometrial epithelial stem cells giving rise to single, non-branching functionalis glands. Several previous studies that have tried to confirm the existence of epithelial stem cells have used methodologies that prevent sampling of the stem cell-rich basalis. More recent findings have provided insight into the efficient regeneration of the human endometrium, which is preferentially evolved in humans and menstruating upper-order primates.WIDER IMPLICATIONSThe unique physiological organization of the human endometrial glandular element, its relevance to stem cell activity and scarless endometrial regeneration will inform reproductive biologists and clinicians to direct their future research to determine disease-specific alterations in glandular anatomy in a variety of endometrial pathological conditions.