Somatic musculature of rotifers <Emphasis Type="Italic">Asplanchna girodi</Emphasis> Guerne, 1888 and <Emphasis Type="Italic">Trichotria pocillum</Emphasis> (Müller, 1776) (Rotifera,Pseudotrrocha, Ploima): Comparative aspect

Comparative study of somatic musculature in illoricate rotifer Asplanchina girodi Guerne, 1888 and loricate Trichotria pocillum (Müller, 1776) has been carried out by the method of phalloidin fluorescence and confocal laser scanning microscopy. Similar layering of muscles is revealed, while significant differences are observed in other aspects. Postcoronal transverse muscle of A. girodi and the dorsal portion of the anterior circular muscle of T. pocillum serve as attachment sites for the refractor muscles. All retractors are formed by smooth muscles or striated muscles, except the lateral retractors of A. girodi, which are formed by the most powerful oblique muscles. In A. girodi there are three pairs of retractors, ten longitudinal muscles, and five circular muscles, with a thick muscular plexus connecting them. In T. pocillum there are four pairs of retractors, five transverse muscles, strong foot retractors, and an arched structure of the head region (new for rotifers). Eight pairs of dorsoventral muscles, as identified in T. pocillum, are completely absent in A. girodi.     

Occurrence of Paramyosin among the Nematomorpha

PREVIOUSLY, the longitudinal body wall muscles of freshwater nematomorphs were considered to be histologically similar to the coelomyarian type muscle fibres common among nematodes^{1, 2} and, although double oblique striations were found by Rauther³ in nematomorph muscle preparations, their underlying structure remained unknown. But on the basis of ultra-structural information, mechanical responses and biochemical analyses⁴, the longitudinal body wall muscles of Paragordius varius (Leidy) and Gordius robustus Leidy are now considered to be of the paramyosin smooth type. The phenomenon of “tight coiling” in these species (Fig. 1A) requires the slow, tonic type muscle structure.     

Blockade by Polyphloretin Phosphate of the Prostaglandin F<Subscript>2α</Subscript>, Action on Isolated Human Bronchi

POLYPHLORETIN phosphate (PPP), a polymer with an inhibitory effect on some enzyme systems, such as alkaline phosphatase and hyaluronidase, has been synthesized by Diczfalusy et al.¹ by phosphorylating phloretin with phosphorus oxychloride. PPP has a molecular weight of about 15,000 and is readily soluble in water at pH 7. It has been tried in the treatment of oedema^2,3 and in vitro it inhibits the aggregation of red blood corpuscles⁴ and selectively antagonizes the effect of prostaglandin E₂ (PGE₂) on the intraocular pressure of the rabbit eye⁵. In the light of this finding we have examined whether PPP (supplied by Dr B. Högberg) could also modify the action of prostaglandins, when tested on some other preparation— in this case isolated human bronchi. During this study an investigation of the inhibition by PPP of the PGE₂ and PGF_2α action on isolated bird colon, rabbit jejunum and uterus has been reported⁶. It has been shown that PGE₁ and usually also PGE₂ have a bronchodilating effect in guinea-pig^7,8 and man⁹, while PGF_2α constricts bronchial smooth muscle in vivo and invitro^8,10,11. PGF_2α and PGE₂ have been isolated from human lungs^12,13 and both seem to be released in the anaphylactic reaction of isolated guinea-pig lung.     

Localization of magnetized electrons in current filaments as a fundamental cause of Coulomb explosion

Mechanisms for generating current filaments in a dense plasma under the action of focused laser pulses and in a Z-pinch configuration are discussed. The main properties of current filaments with a zero and nonzero electron vorticity Ω _e =B?(c/e)?×p _e that originate at magnetic fields in the range 4πn _e m _e c²?B²?4πn _i m _i c² are investigated under the conditions of Coulomb explosion at currents below the ion Alfvén current. A study is made of the equilibrium configurations of nonquasineutral current filaments in a purely longitudinal (B_z) and a purely azimuthal (B_θ) magnetic field and also in a more general case of a helical magnetic field, having two components, under conditions such that the charge separation occurs on a spatial scale on the order of the magnetic Debye radius r_B ? |B|/(4πen_e. It is shown that strong electric fields generated in the current filaments are comparable in magnitude to the atomic field and are capable of accelerating ions to energies of several tens of megaelectronvolts. The ion dynamics in strong electric fields of the filaments is calculated numerically and is shown to lead to the formation of collisionless shock waves on time scales on the order of several inverse ion plasma frequencies ω _pi ^?1 . The possible formation of current filaments on different spatiotemporal scales is considered.     

Downhill exercise alters immunoproteasome content in mouse skeletal muscle

Content of the immunoproteasome, the inducible form of the standard proteasome, increases in atrophic muscle suggesting it may be associated with skeletal muscle remodeling. However, it remains unknown if the immunoproteasome responds to stressful situations that do not promote large perturbations in skeletal muscle proteolysis. The purpose of this study was to determine how an acute bout of muscular stress influences immunoproteasome content. To accomplish this, wild-type (WT) and immunoproteasome knockout lmp7 ^?/? /mecl1 ^?/? (L7M1) mice were run downhill on a motorized treadmill. Soleus muscles were excised 1 and 3 days post-exercise and compared to unexercised muscle (control). Ex vivo physiology, histology and biochemical analyses were used to assess the effects of immunoproteasome knockout and unaccustomed exercise. Besides L7M1 muscle being LMP7/MECL1 deficient, no other major biochemical, histological or functional differences were observed between the control muscles. In both strains, the downhill run shifted the force-frequency curve to the right and reduced twitch force; however, it did not alter tetanic force or inflammatory markers. In the days post-exercise, several of the proteasome’s catalytic subunits were upregulated. Specifically, WT muscle increased LMP7 while L7M1 muscle instead increased β5. These findings indicate that running mice downhill results in subtle contractile characteristics that correspond to skeletal muscle injury, yet it does not appear to induce a significant inflammatory response. Interestingly, this minor stress activated the production of specific immunoproteasome subunits that if knocked out were replaced by components of the standard proteasome. These data suggest that the immunoproteasome may be involved in maintaining cellular homeostasis.     

Effects of mechanical stretching of embryonic tissues on axial structure formation in <Emphasis Type="Italic">Xenopus laevis</Emphasis>

Effect of mechanical stretch on the differentiation of axial anlages and Chordin gene expression was studied in sandwich explants prepared from embryonic tissues of Xenopus laevis at the early gastrula stage in two variants: with dissected or intact dorso-medial region. In the first case, convergent cell movements were suppressed and properly organized axial organs (notochord and somites) were almost completely absent. However, they developed if the explants of such type were artificially stretched in the ventro-dorsal direction. In this case, axial organs elongated in the line of stretching, that is in the direction vertical to their normal orientation. Segmented mesoderm was always in contact with the chord anlage. In situ hybridization revealed that the area of Chordin gene expression was also extended in the direction of stretching. PCR showed that Chordin gene expression in stretched explants with disrupted dorso-medial region was statistically at the same level as in the explants with intact dorso-medial region. At the same time, the corresponding gene expression in unstretched explants with disrupted dorso-medial region was statistically higher. The obtained data indicate that mechanical stretch and associated cell movements are a necessary and sufficient condition for the formation of proper histological structure of axial organs and regulation of Chordin gene expression.     

Differentiation of stem cells isolated from rat skeletal muscles towards cardiomyocytes: The effect of an inhibitor of DNA methylation 5-azacytidine

The effects of the inhibitor of DNA methylation 5-azacytidine on stem (satellite) cells isolated from fetal and definitive skeletal muscles of rats lead to the expression of marker genes of cardiomyogenesis (Gata4, Nkx2.5, connexin-43, n-cadherin, as well as Cacna 1 c encoding the cardiac subunit of the L-type Ca²⁺-channel). Through comparative analysis of the dynamics of expression of key markers of cardiomyogenesis, it was established that satellite cells isolated from fetal muscles have a more expressive potency to cardiomyocyte differentiation in vitro (expression of specific marker genes) compared to cells from muscles of adult animals. In the process of induced cardiomyocyte differentiation, the expression of MyoD and m-cadherin marker genes of skeletal muscle differentiation was not detected, suggesting that in the experiments presented the program of myogenic differentiation of skeletal muscles is inhibited.     

Nonquasineutral relativistic current filaments and their X-ray emission

Nonquasineutral electron current filaments with the azimuthal magnetic field are considered that arise due to the generation of electron vorticity in the initial (dissipative) stage of evolution of a current-carrying plasma, when the Hall number is small (σB/en _e c ? 1) because of the low values of the plasma conductivity and magnetic field strength. Equilibrium filamentary structures with both zero and nonzero net currents are considered. Structures with a zero net current type form on time scales of t < t _sk = (r ₀ω _pe /c)² t _st, where t _sk is the skin time, t _st is the typical time of electron-ion collisions, and r ₀ is the radius of the filament. It is shown that, in nonquasineutral filaments in which the current is carried by electrons drifting in the crossed electric (E _r ) and magnetic (B _θ) fields, ultrarelativistic electron beams on the typical charge-separation scale r _B = B/(4πen _e ) (the so-called magnetic Debye radius) can be generated. It is found that, for comparable electron currents, the characteristic electron energy in filaments with a nonzero net current is significantly lower than that in zero-net-current filaments that form on typical time scales of t < t _sk. This is because, in the latter type of filaments, the oppositely directed electron currents repel one another; as a result, both the density and velocity of electrons increase near the filament axis, where the velocities of relativistic electrons are maximum. Filaments with a zero net current can emit X rays with photon energies ? ω up to 10 MeV. The electron velocity distributions in filaments, the X-ray emission spectra, and the total X-ray yield per unit filament length are calculated as functions of the current and the electron number density in the filament. Analytical estimates of the characteristic lifetime of a radiating filament and the typical size of the radiating region as functions of the plasma density are obtained. The results of calculations are compared with the available experimental data.     

Zebrafish Embryonic Slow Muscle Is a Rapid System for Genetic Analysis of Sarcomere Organization by CRISPR/Cas9, but Not NgAgo

Zebrafish embryonic slow muscle cells, with their superficial localization and clear sarcomere organization, provide a useful model system for genetic analysis of muscle cell differentiation and sarcomere assembly. To develop a quick assay for testing CRISPR-mediated gene editing in slow muscles of zebrafish embryos, we targeted a red fluorescence protein (RFP) reporter gene specifically expressed in slow muscles of myomesin-3-RFP (Myom3-RFP) zebrafish embryos. We demonstrated that microinjection of RFP-sgRNA with Cas9 protein or Cas9 mRNA resulted in a mosaic pattern in loss of RFP expression in slow muscle fibers of the injected zebrafish embryos. To uncover gene functions in sarcomere organization, we targeted two endogenous genes, slow myosin heavy chain-1 (smyhc1) and heat shock protein 90 α1 (hsp90α1), which are specifically expressed in zebrafish muscle cells. We demonstrated that injection of Cas9 protein or mRNA with respective sgRNAs targeted to smyhc1 or hsp90a1 resulted in a mosaic pattern of myosin thick filament disruption in slow myofibers of the injected zebrafish embryos. Moreover, Myom3-RFP expression and M-line localization were also abolished in these defective myofibers. Given that zebrafish embryonic slow muscles are a rapid in vivo system for testing genome editing and uncovering gene functions in muscle cell differentiation, we investigated whether microinjection of Natronobacterium gregoryi Argonaute (NgAgo) system could induce genetic mutations and muscle defects in zebrafish embryos. Single-strand guide DNAs targeted to RFP, Smyhc1, or Hsp90α1 were injected with NgAgo mRNA into Myom3-RFP zebrafish embryos. Myom3-RFP expression was analyzed in the injected embryos. The results showed that, in contrast to the CRISPR/Cas9 system, injection of the NgAgo-gDNA system did not affect Myom3-RFP expression and sarcomere organization in myofibers of the injected embryos. Sequence analysis failed to detect genetic mutations at the target genes. Together, our studies demonstrate that zebrafish embryonic slow muscle is a rapid model for testing gene editing technologies in vivo and uncovering gene functions in muscle cell differentiation.     

Inactivation of Complement by <Emphasis Type="SmallCaps">L</Emphasis>-Asparaginase Preparations not Correlated with Enzyme Content

DELÁGE et al.¹ recently reported that L-asparaginase (L-A) in vitro inhibits human and guinea-pig whole serum complement and that L-A is a potent activator of C1. They therefore proposed that their results may “give a clue to the severe anaphylactic reactions noted in some patients on administration of the drug”. Because guinea-pig serum contains L-A in high quantities and Deláge et al. used reagents and methods that make their data difficult to interpret on a molecular basis, we have reinvestigated the effect of L-A preparations on human and guinea-pig complement.     

The musculoskeletal system of male genitalia in <Emphasis Type="Italic">Curetis bulis</Emphasis> Westwood, 1851 (Lepidoptera,Lycaenidae: Curetinae) and <Emphasis Type="Italic">Paralaxita damajanti</Emphasis> (C. Felder et R. Felder, 1860) (Lepidoptera,Riodinidae: Nemeobiinae)

The muscles of the male genitalia were studied for the first time in two species endemic to the Oriental zoogeographical region, namely Curetis bulis from the subfamily Curetinae (Lycaenidae) and Paralaxita damajanti from the tribe Abisarini (Riodinidae). Both taxa possess a common plan of musculature reflected in the positions of muscles m1, m2(10), m5(7), m7(6), m21, and m28. Two new autapomorphies of Curetis bulis were discovered: the splitting of m4 into two muscles and a shift of the attachment site of one of these muscles onto the dorsal area of the anellus. Apomorphic differences in the position of the genital muscles were found between Paralaxita damajanti and the previously studied Polycaena tamerlana from the family Riodinidae. A new synapomorphy between the latter two species, namely splitting of the aedeagus protractors m6(5), was also found.     

Interaction of various types of photosystem I complexes with exogenous electron acceptors

Interaction of photosystem I (PS I) complexes from cyanobacteria Synechocystis sp. PCC 6803 containing various quinones in the A₁-site (phylloquinone PhQ in the wild-type strain (WT), and plastoquinone PQ or 2,3-dichloronaphthoquinone Cl ₂ NQ in the menB deletion strain) and different numbers of Fe₄S₄ clusters (intact WT and F_X-core complexes depleted of F_A/F_B centers) with external acceptors has been studied. The efficiency of interaction was estimated by measuring the light-induced absorption changes at 820 nm due to the reduction of the special pair of chlorophylls (P₇₀₀ ⁺) by an external acceptor(s). It was shown that externally added Cl ₂ NQ is able to effectively accept electrons from the terminal iron-sulfur clusters of PS I. Moreover, the efficiency of Cl ₂ NQ as external acceptor was higher than the efficiency of the commonly used artificial electron acceptor, methylviologen (MV) for both the intact WT PS I and for the F_X-core complexes. The comparison of the efficiency of MV interaction with different types of PS I complexes revealed gradual decrease in the following order: intact WT?>?menB?>?F_X-core. The effect of MV on the recombination kinetics in menB complexes of PS I with Cl ₂ NQ in the A₁-site differed significantly from all other PS I samples. The obtained effects are considered in terms of kinetic efficiency of electron acceptors in relation to thermodynamic and structural characteristics of PS I complexes.     

Reconstitution of <Emphasis Type="Italic">Salmonella</Emphasis> Flagella attached to Cell Bodies

THE reconstitution in vitro of flagellar filaments from their component flagellin monomers in Salmonella has shown that the filaments have structural polarity and grow at an end distal to the cell body¹; flagella in vivo also grow from their tips^2,3. This suggests that even when flagella are attached to living cells, filaments may be reconstituted from exogenous flagellin monomers at the tips in appropriate conditions. In spite of some negative results⁴, we have been encouraged^5–10 to re-examine the question.     

Bacteriochlorophylls in Gliding Filamentous Prokaryotes from Hot Springs

WE have found bacteriochlorophyll-like pigments in two types of filamentous gliding prokaryotes that occur abundantly in alkaline hot springs. They are temporarily designated F-l and F-2. Representatives of F-2, found in hot springs of Iceland, Japan, New Zealand, Guatemala and the western United States, have been isolated in pure culture. They often exist as thick gelatinous mats up to about 70° C and are bright orange from the high content of carotenoids, but in North America they are normally covered by a layer of blue-green algae such as Synechococcus sp. Because of their colour and morphological characteristics, F-2 filaments were previously thought to be members of the heterotrophic, achlorophyllous flexibacteria^1,2. The trichomes are 0.5-1.0µm in diameter and of varying lengths. They are motile and glide on agar substrates at 45° C or 60° C at rates of 0.01-0.04µ/s (Fig. 1 A).     

Filamentous Aggregation of Sequestosome-1/p62 in Brain Neurons and Neuroepithelial Cells upon <Emphasis Type="Italic">Tyr-Cre</Emphasis>-Mediated Deletion of the Autophagy Gene <Emphasis Type="Italic">Atg7</Emphasis>

Defects in autophagy and the resulting deposition of protein aggregates have been implicated in aging and neurodegenerative diseases. While gene targeting in the mouse has facilitated the characterization of these processes in different types of neurons, potential roles of autophagy and accumulation of protein substrates in neuroepithelial cells have remained elusive. Here we report that Atg7^f/f Tyr-Cre mice, in which autophagy-related 7 (Atg7) is conditionally deleted under the control of the tyrosinase promoter, are a model for accumulations of the autophagy adapter and substrate sequestosome-1/p62 in both neuronal and neuroepithelial cells. In the brain of Atg7^f/f Tyr-Cre but not of fully autophagy competent control mice, p62 aggregates were present in sporadic neurons in the cortex and other brain regions as well in epithelial cells of the choroid plexus and the ependyma. Western blot analysis confirmed a dramatic increase of p62 abundance and formation of high-molecular weight species of p62 in the brain of Atg7^f/f Tyr-Cre mice relative to Atg7^f/f controls. Immuno-electron microscopy showed that p62 formed filamentous aggregates in neurons and ependymal cells. p62 aggregates were also highly abundant in the ciliary body in the eye. Atg7^f/f Tyr-Cre mice reached an age of more than 2 years although neurological defects manifesting in abnormal hindlimb clasping reflexes were evident in old mice. These results show that p62 filaments form in response to impaired autophagy in vivo and suggest that Atg7^f/f Tyr-Cre mice are a model useful to study the long-term effects of autophagy deficiency on the homeostasis of different neuroectoderm-derived cells.     

Cloning and expression analysis of zygote arrest 1 (<Emphasis Type="Italic">Zar1</Emphasis>) in New Zealand white rabbits

Zygote arrest 1 (Zar1) is an oocyte-specific maternal-effect gene. Previous studies indicate that Zar1 plays important role in early embryo development, but little is known about its function in rabbit. The objectives of this study were to clone the New Zealand white rabbit Zar1 gene and to investigate its expression in various organs in groups of animals with different reproductive traits. We obtained a 709-bp Zar1 cDNA fragment consisting of an 8-bp exon 1, 161-bp exon 2, 75-bp exon 3, 271-bp exon 4 and 194-bp 3 ^' sequences. The rabbit Zar1 nucleotide sequence showed per cent identities of 91, 88, 88, 87, 86, 87, 76 and 82% with Zar1 orthologues in human, cattle, sheep, pig, mouse, rat, zebrafish and Xenopus laevis, respectively, indicating a high homology with other species and evolutionary conservation. Quantitative real-time polymerase chain reaction analyses revealed nonoocyte-specific Zar1 expression, with expression in spleen, lung, ovary, uterus, heart, liver and kidney. The expression level was highest in the lung. This study may lay the theoretical foundation for the study of ZAR1’s biological function.     

Antioxidative effect of CLA diet and endurance training in liver and skeletal muscles of rat

The purpose of this study is to investigate the effects of conjugated linoleic acid (CLA) supplementation and endurance exercise on the oxidative/anti-oxidative status in rat liver and skeletal muscles. Sprague-Dawley male rats were randomly divided into HS (high-fat diet sedentary group, n = 8), CS group (CLA supplemented sedentary group, n = 8), and CE group (CLA supplemented exercise group, n = 8). For CLA supplementation, 1.0% CLA was substituted for dietary fat. For endurance exercise, the rats swam for 60 min a day, 5 days a week for 8 weeks. The MDA content, Cu, Zn-SOD and Mn-SOD expression in the soleus muscle (SOM) of the CE group improved significantly compared to the HS (p < 0.01) and CS groups (p < 0.05). Moreover, Mn-SOD expression in both the SOM and extensor digitorum longus muscle (EDL) of the CS were enhanced significantly compared to the HS (p < 0.05). From these results, it was suggested that CLA supplementation under the endurance exercise condition may improve the oxidative status by decreasing the MDA content via potential scavenging of Cu,Zn-SOD, and Mn-SOD protein in red muscle, respectively. Therefore, our study demonstrated long-term endurance exercise with CLA supplementation plays a crucial role for maintenance of antioxidative properties in the skeletal muscle of rat.