Allozymes and the hybrid origin of the parthenogenetic lizardCnemidophorus exsanguis

Summary Allozyme electrophoresis was used to determine the hybrid parentage of the triploid parthenogenetic speciesCnemidophorus exsanguis. 19 of 33 loci were polymorphic inC. exsanguis and/or the 7 potential bisexual progenitors. It was determined from allele distributions thatC. exsanguis containes genomes form 3 different species, probablyC. costatus, C. inornatus andC. septemvittatus.Acknowledgments. We thank R.L. Bezy, W.M. Brown, A.E. Greer, C.S. Lieb, J.L. Patton and K.L. Wright for assistance in the field; the Departments of Game and Fish of Arizona and New Mexico and the Direccion General de la Fauna Silvestre, Mexico for providing collecting permits; and R.L. Bezy, H.W. Greene and D.B. Wake for discussions and criticisms. This research was supported in part by NSF Grants DEB 76-20599 and DEB 81-05615 and by a Research Fellowship in Herpetology from the Natural History Museum of Los Angeles County to DAG.     

Affinity chromatographic preparation of arterial heavy meromyosin subfragment-1

Summary Heavy meromyosin subfragment-1 (HMM S-1) was prepared by papain digestion of arterial myosin or actomyosin and was purified by agarose-ATP affinity chromatography. Proteolysis of crude arterial myosin suspensions was preceded by solubilization. HMM-S-1 thus obtained consisted mainly of a 90,000 dalton polypeptide and fully retained the K⁺- and Ca²⁺-ATPase of the parent myosin. Its affinity to agarose-ATP was comparable to that of skeletal muscle HMM S-1.The support of this work by an EMBO short time fellowship (to R. L.) and by the Deutsche Forschungsgemeinschaft (No. SFB 90, B 7) and the excellent technical assistance byM. Troschka andC. Köhler are gratefully acknowledged.     

Freeze tolerance in the frog,Rana sylvatica

Summary Wood frogs survive extracellular freezing at moderate subzero temperatures (–4°C) for at least 11 days. Freezing survival is aided by the accumulation of high concentrations of glucose as a cryoprotectant in blood and tissues. Glucose production was accompanied by a rapid decline in liver, but not muscle, glycogen levels suggesting that liver is the organ controlling cryoprotectant synthesis.Acknowledgments. This study was supported by grants to L.M.G. from the Kroc Foundation (Santa Ynez, California) and from the National Institute of Dental Research (Grant No. DE-03987). The authors wish to thank K. Yorko, M. Shakin, J. Finan and Mrs N. Manivannan for their technical and secretarial assistance.Acknowledgments. I thank Dr J. Ballantyne, Dr F. Schueler and I. McMurray for help with frog collections and Dr. W. Schmid, Dr J. Bogart and Dr F. Cook for helpful discussions. Supported by an N.S.E.R.C. operating grant and by a grant from the Atkinson Charitable Foundation.     

The tension/length relationship of an insect (Calliphora erythrocephala) supercontracting muscle

Summary The tension/length curves of an insect supercontracting striated muscle are described. Both vertebrate and invertebrate smooth (non-striated) muscles show a close similarity to these curves. Thus, although insects possess only striated muscle, some of these muscles can perform the function of smooth muscle of other animals.I would like to thank Dr.M. P. Osborne for supervizing this work which was supported by an S. R. C. studentship.     

A field-portable racetrack and timer for measuring acceleration and speed of small cursorial animals

Summary We describe a relatively inexpensive, field-portable racetrack and timer that can be used to measure acceleration and maximum speed of small cursorial animals. Procedures for interfacing the racetrack to microprocessors are also outlined.This research was supported by NSF DEB 78-12124, the Miller Institute for Basic Research in Science (University of California, Berkeley), and by the Graduate School Research Fund (University of Washington, Seattle). The authors gladly acknowledge the advice of R. Reinstatler, J.R. Simpson, M.O. Smith, and especially A. M. Hawkins.     

Epidermal sensitivity to hypoxia in the lugworm

Summary Physiological and anatomical data support the idea that in the caudal epidermis of the lugworm,Arenicola marina (L.), there are chemoreceptors detecting variations of oxygen partial pressure in the ambient water.This research was partly supported by a C.N.R.S. grant, AI No. 582 085. We thank Dr P. Dejours and Dr J. Taxi for helpful comments and discussion, Mrs S. Dejours for editing the English of this paper, M.F. Baucher, A. Dorme, F. Kleinbauer, the staff of the Station Biologique de Roscoff and the Service de Microscopie Electronique, C.N.R.S., boulevard Raspail, Paris, for technical assistance.     

The EM immunocytochemical demonstration of lysozyme in macrophage giant cells in sarcoidosis

Summary The giant cells (multinucleate macrophages) of human sarcoidosis have been shown by the unlabelled antibody immunoperoxidase technique at electron microscope level to contain lysozyme within cytoplasmic granules.Acknowledgment. We are grateful to M. R. C. Canada for financial support, to Dr S. Erlandsen for instruction in technique, and to Dr L. Black for help in obtaining fresh material.     

Dystrophic mutation (dy2J) affecting regulation of lactate dehydrogenase (LDH) and pyruvate kinase (PK) in C57BL/6J mice

Summary The genotype difference (dystrophic vs nondystrophic) in the LDH isozymes is observed in kidney. These differences are evident only at birth and at early developmental stages (before the expression of dystrophic symptoms). The tissue specific genotype differences for PK are limited to the thigh muscle (M form) and heart (L form), after the onset of the condition. These differences may reflect the pleiotropic effect of the dy^2J locus during the temporal regulation of these and other enzymes implicated in muscular dystrophy (MD).This research was financed by a Natural Sciences and Engineering Research Council Canada grant to S.M.S.     

External strontium and contractility in single giant muscle fibers of the barnacle

Summary Isometric tension and membrane potential in response to electrical stimulation have been studied on single giant muscle fibers of the barnacle upon replacement of external calcium with strontium. Under these conditions, the membrane response showed after the normal peak depolarization, a plateau phase lasting 3–7 sec before repolarization took place, while the force of contraction showed a linear relation with external strontium concentration. A direct action of strontium ions on contractile proteins (namely troponin) can be ruled out in favor of a triggering action on the sarcoplasmic reticulum, which, in turn, leads to calcium release and development of tension.Acknowledgment. I wish to thank Dr C. C. ashley in whose laboratory the research reported in this paper was performed, and Mrs L. M. Castell for invaluable technical assistance. This work was supported by grant No. 106140/048104235 from Consiglio Nazionale delle Ricerche, Italy.     

A response to monoamines inPeripatopsis moseleyi (Onychophora)

Summary Preparations of longitudinal muscle respond to catecholamines if the ventral nerve cords are present, and also to 5-hydroxytryptamine. The response to 5HT is complex if the central nervous system is present, but muscle alone is probably inhibited.Acknowledgments. It is a pleasure to thank Professor A.C. Brown for providing facilities in the Zoology Department, University of Cape Town, and Mr L.R. Alexander and his colleagues for help in obtaining materials.     

Functional characterization of the human α-cardiac actin mutations Y166C and M305L involved in hypertrophic cardiomyopathy

Inherited cardiomyopathies are caused by point mutations in sarcomeric gene products, including α-cardiac muscle actin (ACTC1). We examined the biochemical and cell biological properties of the α-cardiac actin mutations Y166C and M305L identified in hypertrophic cardiomyopathy (HCM). Untagged wild-type (WT) cardiac actin, and the Y166C and M305L mutants were expressed by the baculovirus/Sf9-cell system and affinity purified by immobilized gelsolin G4-6. Their correct folding was verified by a number of assays. The mutant actins also displayed a disturbed intrinsic ATPase activity and an altered polymerization behavior in the presence of tropomyosin, gelsolin, and Arp2/3 complex. Both mutants stimulated the cardiac β-myosin ATPase to only 50?% of WT cardiac F-actin. Copolymers of WT and increasing amounts of the mutant actins led to a reduced stimulation of the myosin ATPase. Transfection of established cell lines revealed incorporation of EGFP- and hemagglutinin (HA)-tagged WT and both mutant actins into cytoplasmic stress fibers. Adenoviral vectors of HA-tagged WT and Y166C actin were successfully used to infect adult and neonatal rat cardiomyocytes (NRCs). The expressed HA-tagged actins were incorporated into the minus-ends of NRC thin filaments, demonstrating the ability to form hybrid thin filaments with endogenous actin. In NRCs, the Y166C mutant led after 72?h to a shortening of the sarcomere length when compared to NRCs infected with WT actin. Thus our data demonstrate that a mutant actin can be integrated into cardiomyocyte thin filaments and by its reduced mode of myosin interaction might be the basis for the initiation of HCM.     

Retinoic acid enhances the proliferation of smooth muscle cells

Retinoic acid (RA, 10(-5) - 10(-7) M) is shown to enhance the proliferation of cultured rat aortic smooth muscle cells (SMC). This effect is not connected with a synergistic action of RA together with serum mitogens. Moreover, the expression of L1, a surface antigen specific for modulated SMC entering the cell cycle, is amplified by RA treatment.     

Experimentally induced encapsulation ofDiplostomum phoxini (Faust) in the fish host

Summary Experimentally induced encapsulation ofDiplostomum by the hostPhoxinus, is recorded for the first time and requires the metacercariae to develop in fish at a temperature (23–26°C) which is above that naturally encountered.Acknowledgment. It is a pleasure to thank M. R. L. Johnston for his advice.     

Properties of Mycobacteriophage C2

Résumé Le mycobactériophage C2 a une morphologie typique tête-queue, la longueur de la tête étant de 60 nm et celle de la queue de 200 nm. Le génome du phage est un acide désoxyribonucléique. Le phage C2 joue un rôle important dans la génétique mycobactérienne.

---

---

Supported by grant No. MA-2718 from M.R.C., Canada. We thank Dr. E.Mankiewicz for her suggestions and samples, and Mr. L.Berthiaume for assistance in electron microscopy. One of us (J.M.), presently at Dept. Microbiology, University of Ottawa, is a M.R.C. Fellow.     

Dog behaviour as related to spinal cord temperature

Summary 3 dogs could behaviourally modify their own spinal cord temperature (T_{spin. cord}). In a hot environment, 2 dogs did not cool their spinal cord, 1 dog warmed it. The higher the environmental temperature, the higher the chosen T_{spin. cord}. These results seem to imply that this latter dog tended, in warm environment, to behaviourally reduce: T_s>T_{spin. cord} (T_s mean skin temperature). Data obtained previously support this explanation.This experiment has been supported by the Centre National de la Recherche Scientifique (L.A. No. 181 C.N.R.S.) and by the Institut National de la Santé et de la Recherche Médicale I.N.S.E.R.M./A.T.P. No. 4-74-25).     

Improved diffraction patterns from isolated heart muscle with infrared light

Summary Diffraction measurement of myofilament overlap can be made with greater resolution or extended to thicker heart muscle preparations by using light of a near IR wavelength.Supported in part by National Heart and Lung Institute, grant 5 R01 HL 18668-02.I wish to thank Dr E. H. Sonnenblick for support, Dr M. Kawai for advice, and Mr Andrew Hopkins, Jr, for technical assistance.     

Studies on the Dd antigen-antibody system. I. The nature of antigen Dd and its antibodies

Summary The nature of antigen Dd, an antigen present in the extracts of human dandruff which precipitates human sera selectively, and antibodies reacting with it are reported.This work was supported through U.G.C. Grant No. F.23-230/75/SR II. H.K. participated in this study, first as J.R.F. of U.G.C. and then as S.R.F. of I.C.M.R. We are grateful to Dr Baruch S. Blumberg for his invaluable suggestions and to Professor H. Walter for the gift of IgG, IgM and IgA immune sera.     

Different intrafusal fiber composition of spindles in sheep and pig extraocular muscles

Summary Histochemical profiles of intrafusal fibers have been examined in muscle spindles of extraocular muscles of sheep and pig. Results show that in the sheep the intrafusal content presents, in addition to chain fibers, at least one bag₁ and one bag₂ fiber, whereas in the pig almost all the spindles are bag₁-fiber spindles.Acknowledgment. This study was supported by grants from C.N.R. and M.P.I.     

Transport synaptosomal du Tryptophane et de la Tyrosine cérébrale. Existence de systèmes de capture d'affinité différente

Summary The existence of low and high affinity systems for tryptophan and tyrosine uptake by synaptosomes were demonstrated in vitro in the rat mesencephalon.

---

---

Ce travail réalisé dans le laboratoire du ProfesseurM. Jouvet a bénéficié de l'aide de l'I.N.S.E.R.M. (No. U-52), de la D.R.M.E. (contrat No. 72-108) et du C.N.R.S. (Laboratoire associé No. 162).

---

Nous remercions tout particulièrement MmeG. Veuillet et MmeR. Juruguen pour leur précieuse aide technique.     

The development and function of regulatory T cells

Regulatory T cells (Tregs) are a critical subset of T cells that mediate peripheral tolerance. There are two types of Tregs: natural Tregs, which develop in the thymus, and induced Tregs, which are derived from naive CD4⁺ T cells in the periphery. Tregs utilize a variety of mechanisms to suppress the immune response. While Tregs are critical for the peripheral maintenance of potential autoreactive T cells, they can also be detrimental by preventing effective anti-tumor responses and sterilizing immunity against pathogens. In this review, we will discuss the development of natural and induced Tregs as well as the role of Tregs in a variety of disease settings and the mechanisms they utilize for suppression. C. J. Workman, A. L. Szymczak-Workman, L. W. Collison, and M. R. Pillai contributed equally.