Bilobed Structure Research Articles

Description of the final stadium larva of Cryptophaea vietnamensis (van Tol & Rozendaal, 1995) (Odonata: Euphaeidae) from Vietnam.

The final stadium larva of the Cryptophaea vietnamensis (van Tol & Rozendaal, 1995) from Vietnam is described and illustrated based on specimens reared to adulthood. This is the first record of a larva of the genus Cryptophaea Hämäläinen, 2003. The larvae of C. vietnamensis are seldom encountered, but where present they may co-occur with larvae of the genera Anisopleura Selys, 1853, Bayadera Selys, 1853, and Euphaea Selys, 1840. The larvae of Cryptophaea are very similar to those of Bayadera but can be separated from known larvae of that genus by the distal margin of the ligula being a pronounced bilobed structure and the spurs on outer margin of mandible being poorly developed.

Hydrogen/Deuterium Exchange Mass Spectrometry Provides Insights into the Role of Drosophila Testis-Specific Myosin VI Light Chain AndroCaM.

In Drosophila testis, myosin VI plays a special role, distinct from its motor function, by anchoring components to the unusual actin-based structures (cones) that are required for spermatid individualization. For this, the two calmodulin (CaM) light-chain molecules of myosin VI are replaced by androcam (ACaM), a related protein with 67% identity to CaM. Although ACaM has a similar bi-lobed structure to CaM, with two EF hand-type Ca2+ binding sites per lobe, only one functional Ca2+ binding site operates in the amino-terminus. To understand this light chain substitution, we used hydrogen-deuterium exchange mass spectrometry (HDX-MS) to examine dynamic changes in ACaM and CaM upon Ca2+ binding and interaction with the two CaM binding motifs of myosin VI (insert2 and IQ motif). HDX-MS reveals that binding of Ca2+ to ACaM destabilizes its N-lobe but stabilizes the entire C-lobe, whereas for CaM, Ca2+ binding induces a pattern of alternating stabilization/destabilization throughout. The conformation of this stable holo-C-lobe of ACaM seems to be a "prefigured" version of the conformation adopted by the holo-C-lobe of CaM for binding to insert2 and the IQ motif of myosin VI. Strikingly, the interaction of holo-ACaM with either peptide converts the holo-N-lobe to its Ca2+-free, more stable, form. Thus, ACaM in vivo should bind the myosin VI light chain sites in an apo-N-lobe/holo-C-lobe state that cannot fulfill the Ca2+-related functions of holo-CaM required for myosin VI motor assembly and activity. These findings indicate that inhibition of myosin VI motor activity is a precondition for transition to an anchoring function.

Histopathological Effects of Cadmium Chloride (CdCl2) Exposure on the Liver of Freshwater Fish Heteropneustes fossilis

The histopathological effects of CdCl2 on the liver of H. fossilis by acute and chronic exposure of 25 mg/l, 50 mg/l, and 75 mg/l during interval of 30 and 60 days were studied. Similarly, control groups were operated simultaneously with experimental set-up to study alterations in the morphology and architecture of liver in order to understand the injury. The Liver of H. fossilis Normally, the liver of H. fossilis displayed a bilobed structure consisting of polygonal hepatocytes that were radially disposed around the hepatic veins, which maintained its characteristic architecture with an evident nucleus and interspersed binding connective tissue. Histopathological changes by exposure to CdCl2 Both acute and chronic exposure were associated with hematogenesis characterized by darker fragile livers with hepatocyte hypertrophy. Hepatocytes lost the polygonal shape and were dispersed; cytoplasmic vacuolization, pyknotic changes, and bile canaliculi dilation. Prolonged exposure worsened these effects, and resulted in marked atrophy accompanied by necrosis, cellular shrinkage and tissue distortion. In addition, higher concentrations of CdCl2resulted in enlarged Kupffer cells, ruptured nuclei, cellular necrosis and focal necrosis in liver tissue. Our results suggest that progressive histopathological alterations in the liver of H. fossilis due to CdCl2exposure, signifying the susceptibility of this organ to heavy metal toxicity and its ecological prospects in aquatic environs.

Characterizing the nucleus of comet 162P/Siding Spring using ground-based photometry

ABSTRACT Comet 162P/Siding Spring is a large Jupiter-family comet with extensive archival lightcurve data. We report new r-band nucleus light curves for this comet, acquired in 2018, 2021, and 2022. With the addition of these light curves, the phase angles, at which the nucleus has been observed, range from 0.39○ to 16.33○. We absolutely calibrate the comet light curves to r-band Pan-STARRS 1 magnitudes, and use these light curves to create a convex shape model of the nucleus by convex lightcurve inversion. The best-fitting shape model for 162P has axis ratios a/b = 1.56 and b/c = 2.33, sidereal period P = 32.864 ± 0.001 h, and a rotation pole oriented towards ecliptic longitude λE = 118○ ± 26○ and latitude βE = −50○ ± 21○. We constrain the possible nucleus elongation to lie within 1.4 < a/b < 2.0 and discuss tentative evidence that 162P may have a bilobed structure. Using the shape model to correct the light curves for rotational effects, we derive a linear phase function with slope β = 0.051 ± 0.002 mag deg−1 and intercept Hr(1, 1, 0) = 13.86 ± 0.02 for 162P. We find no evidence that the nucleus exhibited an opposition surge at phase angles down to 0.39°. The challenges associated with modelling the shapes of comet nuclei from light curves are highlighted, and we comment on the extent to which we anticipate that Legacy Survey of Space and Time will alleviate these challenges in the coming decade.

Dynamics of Target DNA Binding and Cleavage by Staphylococcus aureus Cas9 as Revealed by High-Speed Atomic Force Microscopy.

Programmable DNA binding and cleavage by CRISPR-Cas9 has revolutionized the life sciences. However, the off-target cleavage observed in DNA sequences with some homology to the target still represents a major limitation for a more widespread use of Cas9 in biology and medicine. For this reason, complete understanding of the dynamics of DNA binding, interrogation and cleavage by Cas9 is crucial to improve the efficiency of genome editing. Here, we use high-speed atomic force microscopy (HS-AFM) to investigate Staphylococcus aureus Cas9 (SaCas9) and its dynamics of DNA binding and cleavage. Upon binding to single-guide RNA (sgRNA), SaCas9 forms a close bilobed structure that transiently and flexibly adopts also an open configuration. The SaCas9-mediated DNA cleavage is characterized by release of cleaved DNA and immediate dissociation, confirming that SaCas9 operates as a multiple turnover endonuclease. According to present knowledge, the process of searching for target DNA is mainly governed by three-dimensional diffusion. Independent HS-AFM experiments show a potential long-range attractive interaction between SaCas9-sgRNA and its target DNA. The interaction precedes the formation of the stable ternary complex and is observed exclusively in the vicinity of the protospacer-adjacent motif (PAM), up to distances of several nanometers. The direct visualization of the process by sequential topographic images suggests that SaCas9-sgRNA binds to the target sequence first, while the following binding of the PAM is accompanied by local DNA bending and formation of the stable complex. Collectively, our HS-AFM data reveal a potential and unexpected behavior of SaCas9 during the search for DNA targets.

Reproductive development of common buckwheat (Fagopyrum esculentum Moench) and its wild relatives provides insights into their evolutionary biology.

Understanding the complex inflorescence architecture and developmental morphology of common buckwheat (Fagopyrum esculentum) is crucial for crop yield. However, most published descriptions of early flower and inflorescence development in Polygonaceae are based on light microscopy and often documented by line drawings. In Fagopyrum and many other Polygonaceae, an important inflorescence module is the thyrse, in which the primary axis never terminates in a flower and lateral cymes (monochasia) produce successively developing flowers of several orders. Each flower of a cyme is enclosed together with the next-order flower by a bilobed sheathing bract-like structure of controversial morphological nature. We explored patterns of flower structure and arrangement in buckwheat and its wild relatives, using comparative morphology, scanning electron microscopy and X-ray microtomography. Our data support interpretation of the sheathing bract as two congenitally fused phyllomes (prophylls), one of which subtends a next-order flower. In tepal-like bract, a homeotic mutant of F. esculentum, the bilobed sheathing bract-like organ acquires tepal-like features and is sometimes replaced by two distinct phyllomes. Wild representatives of F. esculentum (ssp. ancestrale) and most cultivars of common buckwheat possess an indeterminate growth type with lateral thyrses produced successively on the primary inflorescence axis until cessation of growth. In contrast, determinate cultivars of F. esculentum develop a terminal thyrse after producing lateral thyrses. In contrast to F. esculentum, the occurrence of a terminal thyrse does not guarantee a determinate growth pattern in F. tataricum. The number of lateral thyrses produced before the terminal thyrse on the main axis of F. tataricum varies from zero to c. 19. The nine stages of early flower development formally recognized here and our outline of basic terminology will facilitate more standardized and readily comparable descriptions in subsequent research on buckwheat biology. Non-trivial relative arrangements of tepals and bracteoles in Fagopyrum and some other Polygonaceae require investigation using refined approaches to mathematical modelling of flower development. Our data on inflorescence morphology and development suggest contrasting evolutionary patterns in the two main cultivated species of buckwheat, F. esculentum and F. tataricum. The genus Fagopyrum offers an excellent opportunity for evo-devo studies related to inflorescence architecture.

MRI anatomical investigation of rabbit prostate gland

The aim of the study was to provide diagnostic imaging data on rabbit prostate complex by means of magnetic resonance imaging (MRI) with regard to their use in morphological investigations of the gland. Six anaesthetised sexually mature clinically healthy New Zealand White rabbits, 8 months of age, with body weight 2.8-3.2 kg were used. The pelvic cavity and pelvic organs were investigated in the sagittal, dorsal and transversal planes from the 7th lumbar (L7) to the 1st coccygeal (C1) vertebra with 2-mm slice thickness using a Magnetom Essenza 1.5T tunnel MRI scanner. The prostate complex (proprostate, prostate and paraprostate parts) demonstrated signal hyperintensity on T1-weighted MRI images. The prostate capsule was hyperintense compared to glandular parenchyma. The prostate complex was visualised on slices between the caudal part of the first sacral and cranial part of the third sacral vertebrae. The prostate part signal was hyperintense on T2-weighted MRI images. The shape of the prostate complex in dorsal view was craniocaudally elongated, oval and localised bilate­rally from prostatic urethra in ventrodorsal view. The transverse T2 image of the pelvis through the 2nd sacral vertebra delineated the prostate part of the gland as a bilateral bilobed oval structure with hypointense parenchyma, embraced by a hyperintense capsule. The intrapelvic localisation and the shape of MRI image of healthy rabbit prostate complex is a species-specific morphological feature. The signal hyperintensity of rabbit prostate complex was higher on T2-weighted images. The T2 hyperintensity of prostate part vs hypointensity of proprostate and paraprostate parts provide evidence for the presence of substantial amount of glandular elements, presuming a dominating role of prostate part in the secretory function of the glandular complex.

Morphology and Morphometry of the Brain of African side necked turtle ‎‎(Pelusios castaneus): A Preliminary Investigation‎

The brain and spinal cord make up the central nervous system and studying its morphology and morphometry in African side necked turtle (Pelusios castaneus) enhance understanding the neurobiology of this reptile. The current study is aimed to document the normal features on gross morphology and morphometry of the brain of Pelusios castaneus, and discuss the structure-function paradigm. The study was conducted on six (6) brains of African side necked turtle without sex differences. The main morphologic features observed were: 1- a pear-shaped olfactory brain, sand-wished between the two eyes and grossly divided into i) olfactory bulb, ii) olfactory tract and iii) olfactory lobe. 2- smooth cerebrum lacking gyri and sulci, and narrowed rostrally but broad caudally, 3- bi-lobed optic structure separating the cerebrum from cerebellum, 4- developed cerebellum with large corpus cerebelli and small flocculus. 5-pons and medulla oblongata were developed, and made up the myelencephalon. The mean body, head and brain weights were 111.69±21.04g, 4.58±0.60g and0.35±0.04g respectively. While brain weight accounts for 0.34% of total body weight and 8% of head weight, brain somatic index was 0.0034±0.0004 and head brain index was 7.60±0.70 respectively. The study provided baseline data on the gross morphology and morphometry of the brain of African side necked turtle (Pelusios castaneus); which is of great benefit in understanding the neurobiology of this reptile.

Structural dynamics in the evolution of a bilobed protein scaffold

Novel biophysical tools allow the structural dynamics of proteins and the regulation of such dynamics by binding partners to be explored in unprecedented detail. Although this has provided critical insights into protein function, the means by which structural dynamics direct protein evolution remain poorly understood. Here, we investigated how proteins with a bilobed structure, composed of two related domains from the periplasmic-binding protein-like II domain family, have undergone divergent evolution, leading to adaptation of their structural dynamics. We performed a structural analysis on ∼600 bilobed proteins with a common primordial structural core, which we complemented with biophysical studies to explore the structural dynamics of selected examples by single-molecule Förster resonance energy transfer and Hydrogen-Deuterium exchange mass spectrometry. We show that evolutionary modifications of the structural core, largely at its termini, enable distinct structural dynamics, allowing the diversification of these proteins into transcription factors, enzymes, and extracytoplasmic transport-related proteins. Structural embellishments of the core created interdomain interactions that stabilized structural states, reshaping the active site geometry, and ultimately altered substrate specificity. Our findings reveal an as-yet-unrecognized mechanism for the emergence of functional promiscuity during long periods of evolution and are applicable to a large number of domain architectures.

Anatomical observation of the right retroperitoneal fascia and its clinical significance in complete mesocolic excision for right colon cancer

Objective: To investigate the anatomic characteristics of the right retroperitoneal fascia and its surgical implementation while performing complete mesocolic excision (CME) for right colon cancer. Methods: A descriptive study was carried out. (1) Clinicopathological data and surgical videos of 17 non-consecutive patients undergoing laparoscopic right hemicolectomy (extended right hemicolectomy) with CME for right colon cancer at Department of Colorectal Surgery of Union Hospital, Fujian Medical University between January 2020 and October 2020 were retrospectively collected. The construction of right retroperitoneal fascia was observed from caudal dorsal direction and caudal ventral direction. (2) Three postoperative specimens from 3 cases undergoing laparoscopic right hemicolectomy with CME for right colon cancer in June 2020 were prospectively included to observe anatomy and examine histology. (3) Five abdominal cadaver specimens from the Department of Anatomy of Fujian Medical University were enrolled, including 3 males and 2 females. Anatomical observation and histological studies were performed from the cranial approach and the caudal dorsal approach. Masson staining was used to examine the histology. Results: (1) Surgical video observation: The typical structure of right retroperitoneal fascia could be observed in all the 17 patients. The fascia was a rigid barrier between the posterior space of the ascending colon and the anterior pancreaticoduodenal space behind the transverse colon. The right retroperitoneal fascia should be sharply cut to communicate between the two spaces to avoid entering the right mesocolon by mistake. The severed ventral stump of the right retroperitoneal fascia ran along the dorsal side of the right hemicolon to the lateral side, and the dorsal stump covered the level of the duodenum caudally, and continued to move downward, covering the surface of Gerota's fascia. (2) Observation of 3 surgical specimens: The dorsal side of the right mesocolon was smooth and intact, which could be anchored in the corresponding area of the lateral edge of the duodenum. The ventral stump of the right retroperitoneal fascia could be seen, which attached to the dorsal side of the right mesocolon semi-circularly. Masson staining observation: The ventral stump of the right retroperitoneal fascia ran cephalad, fused with the dorsal side of the right mesocolon tightly and curled. The caudal side of confluence and the dorsal side of the right mesocolon presented a bilobed structure. (3) Anatomy of 5 cadaveric specimens: The right retroperitoneal fascia was a thin fascia structure, which was a rigid barrier between the anterior pancreaticoduodenal space behind the transverse colon and the posterior space of the ascending colon. The ventral stump of the right retroperitoneal fascia (including the dorsal side of the right mesocolon), the dorsal stump of the right retroperitoneal fascia (including part of the duodenal wall) and the dorsal side of the right mesocolon were retrieved for histological examination. The ventral stump of the right retroperitoneal fascia fused with the dorsal side of the right mesocolon by the cephalic side, and the dorsal side of the right hemi-mesocolon on the fusion level by caudal side gradually separated into a double-layer loose fascial structure. The dorsal stump of the right retroperitoneal fascia covered the surface of the duodenum level, moved on from the ventral side to the surface of the prerenal fascia, and continued to the caudal side. Conclusions: The right retroperitoneal fascia is a rigid barrier between the anterior pancreaticoduodenal space behind the transverse colon and the posterior space of the ascending colon. The Toldt fascia formed by fusion with the dorsal lobe of the right colon travels to the edge of the descending and horizontal part of the duodenum and separates again. The right retroperitoneal fascia is attached to the edge of the duodenum, reversing and running on the surface of the prerenal fascia, while the dorsal lobe of the right colon runs in front of the pancreas and duodenum, and shifts to the pancreaticoduodenal fascia. During the operation, this fascia should be identified and cut to penetrate the anterior pancreaticoduodenal space behind the transverse colon and the posterior ascending colon space, which helps to ensure the integrity of the dorsal side of the right hemi-mesocolon.

Correlated conformational dynamics of the human GluN1-GluN2A type N-methyl-D-aspartate (NMDA) receptor.

N-Methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels found in the nerve cell membranes. As a result of overexcitation of NMDARs, neuronal death occurs and may lead to diseases such as epilepsy, stroke, Alzheimer's disease, and Parkinson's disease. In this study, human GluN1- GluN2A type NMDAR structure is modeled based on the X-ray structure of the Xenopus laevis template and missing loops are added by ab-initio loop modeling. The final structure is chosen according to two different model assessment scores. To be able to observe the structural changes upon ligand binding, glycine and glutamate molecules are docked into the corresponding binding sites of the receptor. Subsequently, molecular dynamics simulations of 1.3 μs are performed for both apo and ligand-bound structures. Structural parameters, which have been considered to show functionally important changes in previous NMDAR studies, are monitored as conformational rulers to understand the dynamics of the conformational changes. Moreover, principal component analysis (PCA) is performed for the equilibrated part of the simulations. From these analyses, the differences in between apo and ligand-bound simulations can be summarized as the following: The girdle right at the beginning of the pore loop, which connects M2 and M3 helices of the ion channel, partially opens. Ligands act like an adhesive for the ligand-binding domain (LBD) by keeping the bi-lobed structure together and consequently this is reflected to the overall dynamics of the protein as an increased correlation of the LBD with especially the amino-terminal domain (ATD) of the protein.

Cryo-EM structure of the RNA-guided ribonuclease Cas12g.

Cas12g, the type V-G CRISPR-Cas effector, is an RNA-guided ribonuclease that targets single-stranded RNA substrate. The CRISPR-Cas12g system offers a potential platform for transcriptome engineering and diagnostic applications. We determined the structures of Cas12g-guide RNA complexes in the absence and presence of target RNA by cryo-EM to a resolution of 3.1 Å and 4.8 Å, respectively. Cas12g adopts a bilobed structure with miniature REC2 and Nuc domains, whereas the guide RNAs fold into a flipped 'F' shape, which is primarily recognized by the REC lobe. Target RNA and the CRISPR RNA (crRNA) guide form a duplex that inserts into the central cavity between the REC and NUC lobes, inducing conformational changes in both lobes to activate Cas12g. The structural insights would facilitate the development of Cas12g-based applications.

Investigating gravitational collapse of a pebble cloud to form transneptunian binaries

Context. A large fraction of transneptunian objects are found in binary pairs, ~30% in the cold classical population between ahel ~ 39 and ~48 AU. Observationally, these binaries generally have components of similar size and colour. Previous work has shown that gravitational collapse of a pebble cloud is an efficient mechanism for producing such systems. Since the bi-lobate nature of 2014 MU69 (Arrokoth) was discovered, interest in gravitational collapse as a pathway for forming contact binaries has also grown. Aims. We investigate the formation of binary systems through gravitational collapse by considering a wider range of binary masses than previous studies. We analysed in detail the properties of the bound systems that are formed and compared them to observations. Methods. We performed N-body simulations of gravitational collapse of a pebble cloud using the REBOUND package, with an integrator designed for rotating reference frames and robust collision detection. We conducted a deep search for gravitationally bound particles at the end of the gravitational collapse phase and tested their stability. For all systems produced, not just for the most massive binaries, we investigated the population characteristics of their mass and orbital parameters. Results. We found that gravitational collapse is an efficient producer of bound planetesimal systems. On average, about 1.5 bound systems were produced per cloud in the mass range studied here. In addition to large equal-sized binaries, we found that gravitational collapse produces massive bodies with small satellites and low-mass binaries with a high mass ratio. Our results disfavour the collapse of high-mass clouds, in line with reported upper mass limits of clouds formed by the streaming instability. Gravitational collapse can create binary systems analogous to Arrokoth, and collisions in a collapsing cloud should be gentle enough to preserve a bi-lobed structure.

Metabolic and Proteomic Perspectives of Augmentation of Nutritional Contents and Plant Defense in Vigna unguiculata

The current study enlists metabolites of Alstonia scholaris with bioactivities, and the most active compound, 3-(1-methylpyrrolidin-2-yl) pyridine, was selected against Macrophomina phaseolina. Appraisal of the Alstonia metabolites identified the 3-(1-methylpyrrolidin-2-yl) pyridine as a bioactive compound which elevated vitamins and nutritional contents of Vigna unguiculata up to ≥18%, and other physiological parameters up to 28.9%. The bioactive compound (0.1%) upregulated key defense genes, shifted defense metabolism from salicylic acid to jasmonic acid, and induced glucanase enzymes for improved defenses. The structural studies categorized four glucanase-isozymes under beta-glycanases falling in (Trans) glycosidases with TIM beta/alpha-barrel fold. The study determined key-protein factors (Q9SAJ4) for elevated nutritional contents, along with its structural and functional mechanisms, as well as interactions with other loci. The nicotine-docked Q9SAJ4 protein showed a 200% elevated activity and interacted with AT1G79550.2, AT1G12900.1, AT1G13440.1, AT3G04120.1, and AT3G26650.1 loci to ramp up the metabolic processes. Furthermore, the study emphasizes the physiological mechanism involved in the enrichment of the nutritional contents of V. unguiculata. Metabolic studies concluded that increased melibiose and glucose 6-phosphate contents, accompanied by reduced trehalose (-0.9-fold), with sugar drifts to downstream pyruvate biosynthesis and acetyl Co-A metabolism mainly triggered nutritional contents. Hydrogen bonding at residues G.357, G.380, and G.381 docked nicotine with Q9SAJ4 and transformed its bilobed structure for easy exposure toward substrate molecules. The current study augments the nutritional value of edible stuff and supports agriculture-based country economies.

Mechanism of Crosstalk between the LSD1 Demethylase and HDAC1 Deacetylase in the CoREST Complex

SummaryThe transcriptional corepressor complex CoREST is one of seven histone deacetylase complexes that regulate the genome through controlling chromatin acetylation. The CoREST complex is unique in containing both histone demethylase and deacetylase enzymes, LSD1 and HDAC1, held together by the RCOR1 scaffold protein. To date, it has been assumed that the enzymes function independently within the complex. Now, we report the assembly of the ternary complex. Using both structural and functional studies, we show that the activity of the two enzymes is closely coupled and that the complex can exist in at least two distinct states with different kinetics. Electron microscopy of the complex reveals a bi-lobed structure with LSD1 and HDAC1 enzymes at opposite ends of the complex. The structure of CoREST in complex with a nucleosome reveals a mode of chromatin engagement that contrasts with previous models.

The cephalic morphology of the troglobiontic cholevine species Troglocharinus ferreri (Coleoptera, Leiodidae).

Leiodidae are the second largest subterranean radiation of beetles at family rank. To explore morphological trends linked with troglobiontic habits and characters with potential phylogenetic significance, the head of the cave-dwelling species Troglocharinus ferreri (Cholevinae, Leptodirini) was examined in detail. Overall, the general pattern is similar to what is found in Catops ventricosus (Cholevini). Shared apomorphic features include a fully exposed anterolateral concavity containing the antennal socket, a distinct bead above this depression, a bilobed lip-like structure anterad the labrum, a flat elevated portion of the ventral mandibular surface, and a ventral process at the proximomesal edge of this mandibular area. The tentorial structures are well-developed as in C. ventricosus, with a large laminatentorium and somewhat shortened dorsal arms. The mouthparts are largely unmodified, with the exception of unusually well-developed extrinsic maxillary muscles. Features of T. ferreri obviously linked with subterranean habits are the complete lack of compound eyes, circumocular ridges, and optic lobes. A series of characters is similar to conditions found in other genera of Leptodirini: the head capsule completely lacks a protruding ocular region, a distinct neck is missing, the transverse occipital crest is indistinct, and the antennae are elongate and lack a distinct club. Two different trends of cephalic transformations occur in troglobiontic Leptodirini, with some genera like Troglocharinus and Leptodirus having elongated head capsules and antennae, and others having broadened, more transverse heads. In contrast, the modifications are more uniform in the closely related Ptomaphagini, with a pattern distinctly differing from Leptodirini: the head is transverse, with a distinctly protruding ocular region, a distinct transverse occipital crest, and a very narrow neck region.

Unraveling the molecular conformations of a single ruthenium complex adsorbed on the Ag(111) surface by calculations.

The tris(dibenzoylmethanato)ruthenium (Ru(dbm)3) molecule has recently been characterized by scanning tunneling microscopy (STM) experiments upon adsorption on Ag(111). The adsorbed Ru(dbm)3 molecule shows two conformations with respect to the [11[combining macron]0] direction of the substrate, one with a three-lobed feature and the other one with a bi-lobed structure. For each of these structures, the molecule can take two geometries (states). Molecular mechanics calculations in a semi-empirical framework and STM calculated images reveal that these states on the substrate originate from the enantiomer of the Ru(dbm)3 molecule in the case of three-lobed structure and from the rotation of the two phenyls in the top dbm moities for the bi-lobed form.

Electron Acceptive Mass Tag for Mass Spectrometric Imaging-Guided Synergistic Targeting to Mice Brain Glutamate Receptors.

Dysfunctional glutamate receptors (GluRs) have been implicated in neurological disorders and injuries. Hetero-tetrameric assemblies of different GluR subunits or splicing variants have distinct spatiotemporal expression patterns and pharmacological properties. Mass spectrometric imaging of GluRs-targeted small molecules is important for determining the regional preferences of these compounds. We report herein the development of a mass tag covalently bonded with glutamate or N-methyl-d-aspartate that functions as both an electron acceptor to generate mass spectrometric signals on irradiated (Bi2O3)0.07(CoO)0.03(ZnO)0.9 nanoparticles with the third harmonic (355 nm) of Nd3+:YAG laser and as the core component to target bilobed clamshell-like structures of GluRs. In this approach, different molecules produce the same tag ion. It provides a new avenue for quantitative assessment of spatial densities of different compounds, which cannot be achieved with well-established stable isotope labeling technique due to different ionization efficiency of different compounds. Various coexisting endogenous molecules are also simultaneously detected for investigation of overall physiological changes induced by these compounds. Because semiconductors do not generate background peaks, this method eliminates interferences from organic matrix materials that are used in regular MALDI (matrix assisted laser desorption ionization). The localized ionization provides high spatial resolution that can be down to sub-micrometers.

Architecture of the TRPM2 channel and its activation mechanism by ADP-ribose and calcium.

Transient receptor potential melastatin 2 (TRPM2) is a calcium-permeable, non-selective cation channel that has an essential role in diverse physiological processes such as core body temperature regulation, immune response and apoptosis1-4. TRPM2 is polymodal and can be activated by a wide range of stimuli1-7, including temperature, oxidative stress and NAD+-related metabolites such as ADP-ribose (ADPR). Its activation results in both Ca2+ entry across the plasma membrane and Ca2+ release from lysosomes8, and has been linked to diseases such as ischaemia-reperfusion injury, bipolar disorder and Alzheimer's disease9-11. Here we report the cryo-electron microscopy structures of the zebrafish TRPM2 in the apo resting (closed) state and in the ADPR/Ca2+-bound active (open) state, in which the characteristic NUDT9-H domains hang underneath the MHR1/2 domain. We identify an ADPR-binding site located in the bi-lobed structure of the MHR1/2 domain. Our results provide an insight into the mechanism of activation of the TRPM channel family and define a framework for the development of therapeutic agents to treat neurodegenerative diseases and temperature-related pathological conditions.

Comparative Anatomical Study of thyroid gland in adult indigenous gazelle (Gazella subgutturosa) and sheep

The present work was carried out on 12 adult healthy indigenous gazelle and sheep (6 gazelle and 6 sheep) to study the anatomical features of thyroid gland in these two animals and to compare between them. The present findings showed that the thyroid gland in both species was made up of two reddish- brown bi-lobed structure (right and left lobes) connected by a thin tissue ; an isthmus, they were asymmetrically located on the cranial portion on the lateral side of the trachea in gazelle, while in sheep they located ventrolaterally. The isthmus connect the right and left lobes from there caudal extremity in gazelle while in sheep from there caudal ends about 5 mm and it cross the ventral aspect of the trachea about 7th – 8th tracheal ring level in gazelle, whereas in sheep at 4th tracheal ring. The anatomical data revealed no significant important in the weight of the gland between gazelle and sheep, and between left and right lobe in both gazelle and sheep in weight, dimensions and volume, but significantly importance between gazelle and sheep in the length, width and volume of isthmus at p<0.05 and in the length of the right and left lobe and only thickness of the right lobe between gazelle and sheep at p<0.05. thyroid gland was supplied by the cranial and caudal thyroid arteries in gazelle, while in sheep through the dorsal and ventral thyroidal arteries, all arteries were originate from the common carotid artery .Keyword: Gazelle, Thyroid gland, Isthmus, Right lobe, left lobe, Thyroid artery.