Antiviral drug recognition and elevator-type transport motions of CNT3

Nucleoside analogs have broad clinical utility as antiviral drugs. Key to their systemic distribution and cellular entry are human nucleoside transporters. Here, we establish that the human concentrative nucleoside transporter 3 (CNT3) interacts with antiviral drugs used in the treatment of coronavirus infections. We report high-resolution single-particle cryo-electron microscopy structures of bovine CNT3 complexed with antiviral nucleosides N4-hydroxycytidine, PSI-6206, GS-441524 and ribavirin, all in inward-facing states. Notably, we found that the orally bioavailable antiviral molnupiravir arrests CNT3 in four distinct conformations, allowing us to capture cryo-electron microscopy structures of drug-loaded outward-facing and drug-loaded intermediate states. Our studies uncover the conformational trajectory of CNT3 during membrane transport of a nucleoside analog antiviral drug, yield new insights into the role of interactions between the transport and the scaffold domains in elevator-like domain movements during drug translocation, and provide insights into the design of nucleoside analog antiviral prodrugs with improved oral bioavailability.

Molecular basis of polyspecific drug and xenobiotic recognition by OCT1 and OCT2

A wide range of endogenous and xenobiotic organic ions require facilitated transport systems to cross the plasma membrane for their disposition. In mammals, organic cation transporter (OCT) subtypes 1 and 2 (OCT1 and OCT2, also known as SLC22A1 and SLC22A2, respectively) are polyspecific transporters responsible for the uptake and clearance of structurally diverse cationic compounds in the liver and kidneys, respectively. Notably, it is well established that human OCT1 and OCT2 play central roles in the pharmacokinetics and drug-drug interactions of many prescription medications, including metformin. Despite their importance, the basis of polyspecific cationic drug recognition and the alternating access mechanism for OCTs have remained a mystery. Here we present four cryo-electron microscopy structures of apo, substrate-bound and drug-bound OCT1 and OCT2 consensus variants, in outward-facing and outward-occluded states. Together with functional experiments, in silico docking and molecular dynamics simulations, these structures uncover general principles of organic cation recognition by OCTs and provide insights into extracellular gate occlusion. Our findings set the stage for a comprehensive structure-based understanding of OCT-mediated drug-drug interactions, which will prove critical in the preclinical evaluation of emerging therapeutics.

Molecular basis of polyspecific drug binding and transport by OCT1 and OCT2

A wide range of endogenous and xenobiotic organic ions require facilitated transport systems to cross the plasma membrane for their disposition 1, 2 . In mammals, organic cation transporter subtypes 1 and 2 (OCT1 and OCT2, also known as SLC22A1 and SLC22A2, respectively) are polyspecific transporters responsible for the uptake and clearance of structurally diverse cationic compounds in the liver and kidneys, respectively 3, 4 . Notably, it is well established that human OCT1 and OCT2 play central roles in the pharmacokinetics, pharmacodynamics, and drug-drug interactions (DDI) of many prescription medications, including metformin 5, 6 . Despite their importance, the basis of polyspecific cationic drug recognition and the alternating access mechanism for OCTs have remained a mystery. Here, we present four cryo-EM structures of apo, substrate-bound, and drug-bound OCT1 and OCT2 in outward-facing and outward-occluded states. Together with functional experiments, in silico docking, and molecular dynamics simulations, these structures uncover general principles of organic cation recognition by OCTs and illuminate unexpected features of the OCT alternating access mechanism. Our findings set the stage for a comprehensive structure-based understanding of OCT-mediated DDI, which will prove critical in the preclinical evaluation of emerging therapeutics.

Methotrexate recognition by the human reduced folate carrier SLC19A1

Folates are essential nutrients with important roles as cofactors in one-carbon transfer reactions, being heavily utilized in the synthesis of nucleic acids and the metabolism of amino acids during cell division^1,2. Mammals lack de novo folate synthesis pathways and thus rely on folate uptake from the extracellular milieu³. The human reduced folate carrier (hRFC, also known as SLC19A1) is the major importer of folates into the cell^1,3, as well as chemotherapeutic agents such as methotrexate^4-6. As an anion exchanger, RFC couples the import of folates and antifolates to anion export across the cell membrane and it is a major determinant in methotrexate (antifolate) sensitivity, as genetic variants and its depletion result in drug resistance^4-8. Despite its importance, the molecular basis of substrate specificity by hRFC remains unclear. Here we present cryo-electron microscopy structures of hRFC in the apo state and captured in complex with methotrexate. Combined with molecular dynamics simulations and functional experiments, our study uncovers key determinants of hRFC transport selectivity among folates and antifolate drugs while shedding light on important features of anion recognition by hRFC.

Recent advances on the inhibition of human solute carriers: Therapeutic implications and mechanistic insights

Solute carriers (SLCs) are membrane transport proteins tasked with mediating passage of hydrophilic molecules across lipid bilayers. Despite the extensive roles played in all aspects of human biology, SLCs remain vastly under-explored as therapeutic targets. In this brief review, we first discuss a few successful cases of drugs that exert their mechanisms of action through inhibition of human SLCs, and introduce select examples of human SLCs that have untapped therapeutic potential. We then highlight two recent structural studies which uncovered detailed structural mechanisms of inhibition exhibited against two different human major facilitator superfamily (MFS) transporters of clinical relevance.

Toward a Molecular Basis of Cellular Nucleoside Transport in Humans

Nucleosides play central roles in all facets of life, from metabolism to cellular signaling. Because of their physiochemical properties, nucleosides are lipid bilayer impermeable and thus rely on dedicated transport systems to cross biological membranes. In humans, two unrelated protein families mediate nucleoside membrane transport: the concentrative and equilibrative nucleoside transporter families. The objective of this review is to provide a broad outlook on the current status of nucleoside transport research. We will discuss the role played by nucleoside transporters in human health and disease, with emphasis placed on recent structural advancements that have revealed detailed molecular principles of these important cellular transport systems and exploitable pharmacological features.

Solar-type dynamo behaviour in fully convective stars without a tachocline

In solar-type stars (with radiative cores and convective envelopes like our Sun), the magnetic field powers star spots, flares and other solar phenomena, as well as chromospheric and coronal emission at ultraviolet to X-ray wavelengths. The dynamo responsible for generating the field depends on the shearing of internal magnetic fields by differential rotation. The shearing has long been thought to take place in a boundary layer known as the tachocline between the radiative core and the convective envelope. Fully convective stars do not have a tachocline and their dynamo mechanism is expected to be very different, although its exact form and physical dependencies are not known. Here we report observations of four fully convective stars whose X-ray emission correlates with their rotation periods in the same way as in solar-type stars. As the X-ray activity-rotation relationship is a well-established proxy for the behaviour of the magnetic dynamo, these results imply that fully convective stars also operate a solar-type dynamo. The lack of a tachocline in fully convective stars therefore suggests that this is not a critical ingredient in the solar dynamo and supports models in which the dynamo originates throughout the convection zone.

Predictive features of ligand-specific signaling through the estrogen receptor

Some estrogen receptor‐α (ERα)‐targeted breast cancer therapies such as tamoxifen have tissue‐selective or cell‐specific activities, while others have similar activities in different cell types. To identify biophysical determinants of cell‐specific signaling and breast cancer cell proliferation, we synthesized 241 ERα ligands based on 19 chemical scaffolds, and compared ligand response using quantitative bioassays for canonical ERα activities and X‐ray crystallography. Ligands that regulate the dynamics and stability of the coactivator‐binding site in the C‐terminal ligand‐binding domain, called activation function‐2 (AF‐2), showed similar activity profiles in different cell types. Such ligands induced breast cancer cell proliferation in a manner that was predicted by the canonical recruitment of the coactivators NCOA1/2/3 and induction of the GREB1 proliferative gene. For some ligand series, a single inter‐atomic distance in the ligand‐binding domain predicted their proliferative effects. In contrast, the N‐terminal coactivator‐binding site, activation function‐1 (AF‐1), determined cell‐specific signaling induced by ligands that used alternate mechanisms to control cell proliferation. Thus, incorporating systems structural analyses with quantitative chemical biology reveals how ligands can achieve distinct allosteric signaling outcomes through ERα.

Interrater and intrarater reliability of the functional movement screen

The purpose of this study was to investigate interrater and intrarater reliability of the Functional Movement Screen (FMS) with real-time administration with raters of different educational background and experience. The FMS was assessed with real-time administration in healthy injury-free men and women and included a certified FMS rater for comparison with other raters. A relatively new tool, the FMS, was developed to screen 7 individual movement patterns to classify subjects' injury risk. Previous reliability studies have been published with only one investigating intrarater reliability. These studies had limitations in study design and clinical applicability such as the use of only video to rate or the use of raters without comparison to a certified FMS rater. Raters (n = 4) with varying degrees of FMS experience and educational levels underwent a 2-hour FMS training session. Subjects (n = 19) were rated during 2 sessions, 1 week apart, using standard FMS protocol and equipment. Interrater reliability was good for session 1 (intraclass correlation coefficient [ICC] = 0.89) and for session 2 (ICC = 0.87). The individual FMS movements showed hurdle step as the least reliable (ICC = 0.30 for session 1 and 0.35 for session 2), whereas the most reliable was shoulder mobility (ICC = 0.98 for session 1 and 0.96 for session 2). Intrarater reliability was good for all raters (ICC = 0.81-0.91), with similar ICC regardless of education or previous experience with FMS. The results showed that the FMS could be consistently scored by people with varying degrees of experience with the FMS after a 2-hour training session. Intrarater reliability was not increased with FMS certification.

Epitaxial SrTiO3 films with electron mobilities exceeding 30,000 cm2 V(-1) s(-1)

The study of quantum phenomena in semiconductors requires epitaxial structures with exceptionally high charge-carrier mobilities. Furthermore, low-temperature mobilities are highly sensitive probes of the quality of epitaxial layers, because they are limited by impurity and defect scattering. Unlike many other complex oxides, electron-doped SrTiO(3) single crystals show high (approximately 10(4) cm(2) V(-1) s(-1)) electron mobilities at low temperatures. High-mobility, epitaxial heterostructures with SrTiO(3) have recently attracted attention for thermoelectric applications, field-induced superconductivity and two-dimensional (2D) interface conductivity. Epitaxial SrTiO(3) thin films are often deposited by energetic techniques, such as pulsed laser deposition. Electron mobilities in such films are lower than those of single crystals. In semiconductor physics, molecular beam epitaxy (MBE) is widely established as the deposition method that produces the highest mobility structures. It is a low-energetic, high-purity technique that allows for low defect densities and precise control over doping concentrations and location. Here, we demonstrate controlled doping of epitaxial SrTiO(3) layers grown by MBE. Electron mobilities in these films exceed those of single crystals. At low temperatures, the films show Shubnikov-de Haas oscillations. These high-mobility SrTiO(3) films allow for the study of the intrinsic physics of SrTiO(3) and can serve as building blocks for high-mobility oxide heterostructures.

The incidence, clustering and characteristics of Burkitt lymphoma in the Northwest province of Cameroon

The epidemiology of Burkitt lymphoma (BL) has never been documented in Cameroon. Data were collected from 16 hospitals, the Delegation of Public Health and the regional pathologist in the Northwest province of Cameroon on all BL cases. The incidence of BL in this region is 5.9/100,000 children aged <15 years/year – the second highest incidence documented to date. Significant clustering was also identified in Ndop, a low-lying region with a high malaria endemicity, at 21.5 cases/100,000 children aged <15 year/year ( P < 0.001).

Causes of lead toxicity in a Nigerian city

BACKGROUND

Up to 70% of young Nigerian children have been reported to have blood lead concentrations > or =10 microg/dl.

AIMS

To better elucidate risk factors for lead toxicity among Nigerian families with children at risk for lead toxicity.

METHODS

Two geographic wards in Jos, Nigeria were selected for study, one previously reported to have a high mean blood lead level (37 (SD 13) microg/dl) and one with a lower mean blood lead level (17 (SD 10) microg/dl) in young children. Data pertaining to potential risk factors for lead exposure were collected from children and adults in 34 households.

RESULTS

The mean (SD) blood lead concentration of 275 subjects, aged 3 weeks to 90 years, was 8.7 (5.7) microg/dl (range 1-34 microg/dl); 92 (34%) had concentrations > or =10 microg/dl. In multivariate analysis, an age of 5 years and under, flaking house paint, residence near a gasoline seller, male gender, increasing maternal and paternal education, and use of a lead ore eye cosmetic were independently associated with greater blood lead concentration. Vehicle ownership was associated with reduced lead concentration. Compared with the low-lead ward, residence in the high-lead ward remained significantly associated with greater lead values, indicating that additional factors likely contribute to lead exposure.

CONCLUSION

Although the cause of increased lead levels in Jos appears to be multi-factorial, several remediable sources contribute to lead exposure in Nigeria.

Amelogenesis imperfecta phenotype-genotype correlations with two amelogenin gene mutations

Amelogenin, the predominant matrix protein in developing dental enamel, is considered essential for normal enamel formation, but its exact functions are undefined. Mutations in the AMELX gene that encodes for amelogenin protein cause X-linked amelogenesis imperfecta (AI), with phenotypes characterized by hypoplastic and/or poorly mineralized enamel. Eight different AMELX deletion and substitution mutations have been reported to date. The purpose here was to evaluate the genotype and phenotype of two large kindreds segregating for X-linked AI. Phenotypically affected males in family 1 had yellowish-brown, poorly mineralized enamel; those in family 2 had thin, smooth, hypoplastic enamel. Heterozygous females in both kindreds had vertical hypoplastic grooves in their enamel. DNA was obtained from family members; exons 1-7 of AMELX were amplified and sequenced. Mutational analysis of family 1 revealed a single-base-pair change of A-->T at nucleotide 256, resulting in a His-->Leu change. Analysis of family 2 revealed deletion of a C-nucleotide in codon 119 causing a frameshift alteration of the next six codons, and a premature stop codon resulting in truncation of the protein 18 amino acids shorter than the wild-type. To date, all mutations that alter the C-terminus of amelogenin after the 157th amino acid have resulted in a hypoplastic phenotype. In contrast, other AMELX mutations appear to cause predominantly mineralization defects (e.g. the mutation seen in family 1). This difference suggests that the C-terminus of the normal amelogenin protein is important for controlling enamel thickness.

Genetic manipulation of the odor-evoked distributed neural activity in the Drosophila mushroom body

Odor-induced neural activity was recorded by Ca2+ imaging in the cell body region of the Drosophila mushroom body (MB), which is the second relay of the olfactory central nervous system. The signals recorded are mainly from the cell layers on the brain surface because of the limited penetration of Ca2+-sensitive dyes. The densely packed cell bodies and their accessibility allow visualization of odor-induced population neural activity. It is revealed that odors evoke diffused neural activities in the MB. Although the signals cannot be attributed to individual neurons, patterns of the population neural activity can be analyzed. The activity pattern, but not the amplitude, of an odor-induced population response is specific for the chemical identity of an odor and its concentration. The distribution pattern of neural activity can be altered specifically by genetic manipulation of an odor binding protein and this alteration is closely associated with a behavioral defect of odor preference. These results suggest that the spatial pattern of the distributed neural activity may contribute to coding of odor information at the second relay of the olfactory system.

Serotonin-sensitive leakage channel in Drosophila central neurons

This article reports the analysis of a novel serotonin (5-HT)-sensitive leak channel. The 5-HT responses were recorded in acutely dissociated Drosophila adult and larval central nervous system (CNS) neurons by the patch-clamp method, in an attempt to establish a model preparation suitable for the genetic study of signal transduction underlying central neurotransmission. Focal perfusion or iontophoresis of 5-HT onto some patched neurons induced either an apparent inward or outward current. This apparent outward current is able to cause a strong hyperpolarization of the neuron. This article focuses on the predominant hyperpolarizing response, which is observed in a significant fraction of larger CNS neurons and in different developmental stages. The hyperpolarizing response is in fact mediated by inhibiting an inward leak current, which has a reversal potential around 0 mV. This 5-HT-sensitive leak current appears to be mediated mainly by one type of newly identified leak channel with a similar reversal potential of 0 mV and a conductance of 24 pS. In addition, it was also demonstrated that neurotransmitter-induced responses in both larval and adult Drosophila CNS neurons can be analyzed in this acutely dissociated preparation.

The bladder tumor antigen (BTA) test compared to voided urine cytology in the detection of bladder neoplasms

PURPOSE

Tests to detect recurrent bladder neoplasms are limited and none is consistently accurate. Recent studies suggest that the bladder tumor antigen (BTA) test, an agglutination reaction for basement membrane complexes, is superior to voided urine cytology in clinical practice. We compared BTA and voided urine cytology to bladder washings and cystoscopy, emphasizing diagnostic yield among patients with causes of basement membrane complexes other than bladder cancer.

MATERIALS AND METHODS

Random voided urine specimens from 67 patients with a history of bladder neoplasms were collected before cystoscopy and bladder washing. Urine also was obtained from 34 patients with inflammatory bladder conditions including 5 with a history of prostate cancer. Each urine was tested for BTA according to a commercial kit. Positive results were indicated by yellow on a test pad. Blinded to all other results, each urine and each bladder washing were examined microscopically, and a positive test had malignant/suspicious cells. Bladder biopsies were performed when endoscopic lesions were seen. Specimens were grouped into 4 categories: group 1--biopsy proved bladder neoplasm, group 2--history of bladder cancer but not biopsy proved, group 3--history of prostate cancer and group 4--no history of urological cancer.

RESULTS

Voided urine cytology was positive in 54% of specimens from patients with biopsy proved bladder neoplasms compared to 29% for BTA. Relative yield for voided urine cytology versus BTA was not changed if all group 2 cases having a positive bladder washing and positive cystoscopy were assumed to have bladder cancer, nor was relative yield altered by subsequent short-term followup. Of voided urine specimens 14% from group 1 patients and 41% from group 2 patients had scant cells. Overall diagnostic yield was superior for bladder washing. False-positive BTA occurred in 7 of 34 patients with no history of urological or prostate cancer. There were no false-positive voided urine cytology interpretations in these groups.

CONCLUSIONS

BTA is not superior to voided urine cytology in detecting bladder neoplasms and may be limited by false-positive reactions in patients with other causes of basement membrane complexes in urine. Voided urine samples may be limited by high frequency of hypocellularity. Of 34 patients with a hypocellular urine specimen 4 had biopsy proved bladder cancer. Bladder washing yields best results but requires instrumentation. No test, including cystoscopy, is accurate always.

Characterization of K+ currents and the cAMP-dependent modulation in cultured Drosophila mushroom body neurons identified by lacZ expression

Electrophysiological analysis of cultured neurons provides a potential approach toward understanding the physiological defects that may contribute to abnormal behavior exhibited by mutants of the fruit fly Drosophila. However, its application has been restricted by an inability to identify a particular functional or anatomical subpopulation of neurons from the CNS. To study neurons composing the CNS mushroom body proposed as a center for insect olfactory learning, we utilized a Drosophila enhancer detector line that expresses a lacZ reporter gene in these neurons and identified them in acutely dissociated larval CNS cultures by vital fluorescent staining. The patch-clamp analysis suggests that whole-cell voltage-activated K+ currents can be classified into two types in identified mushroom body neurons. Type 1 current comprises a TEA-sensitive slowly inactivating current and noninactivating component while type 2 current contains a 4-AP-sensitive transient A-current and a noninactivating component. Application of cAMP analogs induced distinct modulation of type 1 and type 2 currents. Our results demonstrate that the expression of the lacZ gene and the subsequent staining do not significantly alter the different types of K+ currents. This initial characterization provides a basis for further analysis of mutations that impair learning and memory resulting from an abnormal cAMP cascade preferentially expressed in the mushroom body.

The possible site of action of 5-hydroxytryptamine, 6-hydroxytryptamine, tryptamine and dopamine on identified neurons in the central nervous system of the snail, Helix aspersa

Intracellular recordings were made from identified neurons in the right parietal ganglion of the snail, Helix aspersa. Cells F 4, 5 and 6 were excited by 5-hydroxytryptamine (5-HT) and inhibited by dopamine while cells in the F 30 area were inhibited by both compounds. Low doses of both tryptamine and 6-HT produced weak excitation of cells F 4, 5 and 6 while higher doses of both compounds inhibit the activity of these cells. In terms of the inhibitory responses, tryptamine and 6-HT are approximately equipotent but between 10 and 100 times less potent than dopamine. d-Tubocurarine reversibly antagonized the excitatory action of 5-HT on cells F 4, 5 and 6 and converted tryptamine and 6-HT excitation to inhibition. In the presence of the antagonist, ergometrine, the dopamine inhibitory response was almost completely abolished while the inhibitory responses to tryptamine and 6-HT were converted to weak excitation. All four agonists inhibited cells in the F 30 area with the following potency ratios: dopamine much greater than tryptamine/6-HT greater than 5-HT. Tubocurarine had no antagonist effects on these responses while ergometrine reduced or blocked all four, often irreversibly. In potassium-free Ringer the inhibitory responses to all four agonists were enhanced. It is concluded that on cells F 4, 5 and 6, low concentrations of tryptamine and 6-HT act on 5-HT receptors while higher concentrations of both agonists act on dopamine receptors. On cells in the F 30 area, 5-HT, 6-HT and tryptamine all act on a dopamine receptor.

Human marrow erythropoiesis in culture: III. Ultrastructural and cytochemical studies of cellular interactions

Human erythroblasts cultured with a methylcellulose clonal assay technique were studied with ultrastructural and cytochemical methods. The intact colonies contained only erythroblasts at a similar stage of maturation, and no macrophages were identified within the colonies. The cultured erythroblasts demonstrated many of the morphologic features described in vivo. Neutral and acid glycoconjugates identified on the plasmalemma stained in a similar way to that seen in vivo with a concanavalin A horseradish peroxidase bridge and dialyzed iron technique. Weak acid phosphatase activity and ferritin-like particles were demonstrated in siderosomes, but these structures lacked peroxidase activity and dialyzed iron reactive acid mucosubstance. Transmission and scanning electron microscopy identified numerous processes which connected early erythroblasts and resembled those described in the marrow of patients with dyserythropoietic disorders. These findings suggest the presence of abnormalities in cultured erythrocytes which should be considered when evaluating pathologic specimens in vitro.

Ultrastructure and cytochemistry of bone marrow granulocytes in culture

Leukocytes from human bone marrow, grown in clonal cell culture with methylcellulose medium, were characterized ultrastructurally and cytochemically, utilizing techniques for demonstrating peroxidase, acid phosphatase, dialyzed iron reactive mucosubstance, antimonate reactive cation and Concanavalin A surface receptors. Neutrophils and eosinophils were identified in culture specimens and in many respects resembled those seen in direct marrow specimens. Cultured neutrophils, however, did not develop secondary (specific) granules and the crystalloids of eosinophil granules appeared abnormal. The strong reaction of neutrophil primary granules with antimonate and dialyzed iron afforded differentiation from unreactive monocyte-macrophage granules and thus distinguished these cell types in culture. Basophils were observed in morphologic preparations and their granules stained most intensely for acid mucosubstance with the dialyzed iron method.

The ultrastructural identification of tissue basophils and mast cells in Hodgkin's disease

Numerous basophils were identified ultrastructurally in a tumorous lymph node from one of 10 patients with Hodgkin's disease. The tissue basophils displayed the same morphologic characteristics as peripheral blood basophils and differed ultrastructurally from mast cells in the same specimen. Large numbers of mast cells were occasionally seen in tumor tissue of patients with Hodgkin's disease. Many of the mast cells in Hodgkin's tumor revealed structural alteration of granules as well as evidence of degranulation when compared with mast cells in tumor-free lymph nodes of patients with Hodgkin's disease. These results indicate that basophils and mast cells may play a role in the inflammatory response in Hodgkin's disease.

Cytochemistry of acid mucosubstance and acid phosphatase in Cryptococcus neoformans

At the ultrastructural level, dialyzed iron stains only the mucoid capsule in Cryptococcus neoformans, converting it from the most lucent to an extremely dense layer and thus demonstrating its content of acid mucosubstance. After lead staining of thin sections of dialyzed iron treated specimens, the wall exhibits a dense inner and translucent outer layer. The inner layer and mucoid capsule appear thicker in the mother than the daughter cell of budding organisms. C. neoformans cells fixed in suspension and incubated in acid phosphatase substrate medium exhibit at the ultrastructural level activity confined to the mucoid capsule, cell wall, and internal extensions presumed to be plasmalemmasomes. Organisms in small blocks or cryostat sections of pellets fixed in clotted fibrin, when incubated for acid phosphatase, reveal moderate to no reactivity in cell wall and mucoid capsule but strong activity in surrounding fibrin aggregates. In the latter specimens, reaction product indicative of acid phosphatase also is evident in the nuclear envelope, in some of the profiles of presumed granular reticulum, in complex lamellar profiles presumed to be Golgi elements, and in small cytoplasmic bodies and large vacuoles. The morphological specimens disclose counterparts of acid phosphatase reactive structures and show lucent cytoplasm segregated by circular mitochondrial profiles and a difference between the thickness and density of the plasmalemma and other cell membranes.