bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorylation of the myosin regulatory light chain plays a role in motility and polarity duringDictyosteliumchemotaxis
Authors: Zhang Hui , Wessels Deborah , Fey Petra , Daniels Karla , Chisholm Rex L. , Soll David R.
Published: April 2021

The myosin regulatory light chain (RLC) of Dictyostelium discoideum is phosphorylated at a single serine site in response to chemoattractant. To investigate the role of the phosphorylation of RLC in both motility and chemotaxis, mutants were generated in which the single phosphorylatable serine was replaced with a nonphosphorylatable alanine. Several independent clones expressing the mutant RLC in the RLC null mutant, mlcR-, were obtained. These S13A mutants were subjected to high resolution computer-assisted motion analysis to assess the basic motile behavior of cells in the absence of a chemotatic signal, and the chemotactic responsiveness of cells to the spatial, temporal and concentration components of natural cAMP waves. In the absence of a cAMP signal, mutant cells formed lateral pseudopods less frequently and crawled faster than wild-type cells. In a spatial gradient of cAMP, mutant cells chemotaxed more efficiently than wild-type cells. In the front of simulated temporal and natural waves of cAMP,mutant cells responded normally by suppressing lateral pseudopod formation. However, unlike wild-type cells, mutant cells did not lose cellular polarity at the peak and in the back of either wave. Since depolarization at the peak and in the descending phase of the natural wave is necessary for efficient chemotaxis, this deficiency resulted in a decrease in the capacity of S13A mutant cells to track natural cAMP waves relayed by wild-type cells, and in the fragmentation of streams late in mutant cell aggregation. These results reveal a regulatory pathway induced by the peak and back of the chemotactic wave that alters RLC phosphorylation and leads to cellular depolarization. We suggest that depolarization requires myosin II rearrangement in the cortex facilitated by RLC phosphorylation, which increases myosin motor function.
Role of Grb2 in EGF-stimulated EGFR internalization
Authors: Yamazaki Tetsuo , Zaal Kristien , Hailey Dale , Presley John , Lippincott-Schwartz Jennifer , Samelson Lawrence E.
Published: April 2021

Grb2 is an adaptor molecule that couples membrane receptors such as the epidermal growth factor receptor (EGFR) to intracellular signaling pathways. To gain insight into the trafficking pathways followed by these molecules after activation by EGF, we visualized Grb2 and EGFR fused to GFP spectral variants in single live cells. In nonstimulated cells, Grb2-YFP was primarily localized diffusely in the cytoplasm, whereas EGFR-CFP was found on the plasma membrane and in endocytic structures localized in the perinuclear area. Within 1 minute of EGF stimulation, Grb2 redistributed to the plasma membrane where it bound EGFR-CFP in an SH2 dependent manner. The plasma membrane then began to dynamically ruffle, and Grb2-YFP and EGFR-CFP were found to internalize together in large macropinocytic structures. These structures were morphologically distinct from conventional, clathrin-derived endosomes and did not label with transferrin, AP-2 or clathrin heavy chain. Evidence that these structures did not require clathrin for internalization came from experiments showing that expression of the C-terminus of AP-180, which inhibited transferrin uptake, had no effect on EGF-induced internalization of EGFR. YFP-tagged Grb2 containing an inhibitory mutation in either N- or C-SH3 domain redistributed to the plasma membrane upon EGF stimulation, but the macropinocytic structures containing Grb2-YFP and EGFR-CFP did not translocate inward and appeared to remain tethered to the plasma membrane. This suggested that the Grb2 SH3 domain was responsible for coupling the membranes containing EGFR with downstream effectors involved in internalization of these membranes. Transferrin uptake was unaffected in the presence of all of the SH3 domain mutants, consistent with the EGF-stimulated EGFR internalization pathway being clathrin-independent. These results demonstrate a role for Grb2 in events associated with a macropinocytic internalization pathway for EGFR in activated cells.
Reactive oxygen species mediate Rac-induced loss of cell-cell adhesion in primary human endothelial cells
Authors: van Wetering Sandra , van Buul Jaap D. , Quik Safira , Mul Frederik P. J. , Anthony Eloise C. , Klooster Jean-Paul ten , Collard John G. , Hordijk Peter L.
Published: April 2021

The integrity of the endothelium is dependent on cell-cell adhesion, which is mediated by vascular-endothelial (VE)-cadherin. Proper VE-cadherin-mediated homotypic adhesion is, in turn, dependent on the connection between VE-cadherin and the cortical actin cytoskeleton. Rho-like small GTPases are key molecular switches that control cytoskeletal dynamics and cadherin function in epithelial as well as endothelial cells. We show here that a cell-penetrating, constitutively active form of Rac (Tat-RacV12) induces a rapid loss of VE-cadherin-mediated cell-cell adhesion in endothelial cells from primary human umbilical veins (pHUVEC). This effect is accompanied by the formation of actin stress fibers and is dependent on Rho activity. However,transduction of pHUVEC with Tat-RhoV14, which induces pronounced stress fiber and focal adhesion formation, did not result in a redistribution of VE-cadherin or an overall loss of cell-cell adhesion. In line with this observation, endothelial permeability was more efficiently increased by Tat-RacV12 than by Tat-RhoV14.

The loss of cell-cell adhesion, which is induced by Tat-RacV12, occurred in parallel to and was dependent upon the intracellular production of reactive oxygen species (ROS). Moreover, Tat-RacV12 induced an increase in tyrosine phosphorylation of a component the VE-cadherin-catenin complex, which was identified as α-catenin. The functional relevance of this signaling pathway was further underscored by the observation that endothelial cell migration, which requires a transient reduction of cell-cell adhesion, was blocked when signaling through ROS was inhibited.

In conclusion, Rac-mediated production of ROS represents a previously unrecognized means of regulating VE-cadherin function and may play an important role in the (patho)physiology associated with inflammation and endothelial damage as well as with endothelial cell migration and angiogenesis.
Altered expression of the 100 kDa subunit of theDictyosteliumvacuolar proton pump impairs enzyme assembly, endocytic function and cytosolic pH regulation
Authors: Liu Tongyao , Mirschberger Christian , Chooback Lilian , Arana Quyen , Dal Sacco Zeno , MacWilliams Harry , Clarke Margaret
Published: April 2021

The vacuolar proton pump (V-ATPase) appears to be essential for viability of Dictyostelium cells. To investigate the function of VatM, the 100 kDa transmembrane V-ATPase subunit, we altered its level. By means of homologous recombination, the promoter for the chromosomal vatM gene was replaced with the promoter for the act6 gene, yielding the mutant strain VatMpr. The act6 promoter is much more active in cells growing axenically than on bacteria. Thus, transformants were selected under axenic growth conditions, then shifted to bacteria to determine the consequences of reduced vatM expression. When VatMpr cells were grown on bacteria,the level of the 100 kDa V-ATPase subunit dropped, cell growth slowed, and the A subunit, a component of the peripheral catalytic domain of the V-ATPase,became mislocalized. These defects were complemented by transformation of the mutant cells with a plasmid expressing vatM under the control of its own promoter. Although the principal locus of vacuolar proton pumps in Dictyostelium is membranes of the contractile vacuole system, mutant cells did not manifest osmoregulatory defects. However, bacterially grown VatMpr cells did exhibit substantially reduced rates of phagocytosis and a prolonged endosomal transit time. In addition, mutant cells manifested alterations in the dynamic regulation of cytosolic pH that are characteristic of normal cells grown in acid media, which suggested that the V-ATPase also plays a role in cytosolic pH regulation.
Interaction of mitochondria with microtubules in the filamentous fungus Neurospora crassa
Authors: Fuchs Florian , Prokisch Holger , Neupert Walter , Westermann Benedikt
Published: April 2021

The establishment and maintenance of the 3D structure of eukaryotic cells depends on active transport and positioning of organelles along cytoskeletal elements. The biochemical basis of these processes is only poorly understood. We analysed the interaction of mitochondria with microtubules in the filamentous fungus Neurospora crassa. Mitochondria were fluorescently labelled by expression of matrix-targeted green fluorescent protein. Upon isolation, mitochondria collapsed to round spherical structures that were still able to interact with microtubules in vitro. Binding of mitochondria to microtubules was dependent on peripherally associated proteins on the organellar surface, and was sensitive to adenine nucleotides. MMM1, a mitochondrial outer membrane protein important for maintenance of normal mitochondrial morphology, was not required. This suggests that the interaction of mitochondria with the cytoskeleton is independent of MMM1. We conclude that mitochondrial morphology is maintained by a complex interplay of extrinsic and intrinsic factors, including ATP-dependent proteins on the organellar surface.
Formation of Hirano bodies in Dictyostelium and mammalian cells induced by expression of a modified form of an actin-crosslinking protein
Authors: Maselli Andrew G. , Davis Richard , Furukawa Ruth , Fechheimer Marcus
Published: April 2021

We report the serendipitous development of the first cultured cell models of Hirano bodies. Myc-epitope-tagged forms of the 34 kDa actin bundling protein (amino acids 1-295) and the CT fragment (amino acids 124-295) of the 34 kDa protein that exhibits activated actin binding and calcium-insensitive actin filament crosslinking activity were expressed in Dictyosteliumand mammalian cells to assess the behavior of these modified forms in vivo. Dictyostelium cells expressing the CT-myc fragment: (1) form ellipsoidal regions that contain ordered assemblies of F-actin, CT-myc, myosin II, cofilin and α-actinin; (2) grow and develop more slowly than wildtype, but produce normal morphogenetic structures; (3) perform pinocytosis and phagocytosis normally; and (4) produce a level of total actin equivalent to wildtype, but a higher level of F-actin. The paracrystalline inclusions bear a striking resemblance to Hirano bodies, which are associated with a number of pathological conditions. Furthermore, expression of the CT fragment in murine L cells results in F-actin rearrangements characterized by loss of stress fibers, accumulation of numerous punctate foci, and large perinuclear aggregates, the Hirano bodies. Thus, failure to regulate the activity and/or affinity of an actin crosslinking protein can provide a signal for formation of Hirano bodies. More generally, formation of Hirano bodies is a cellular response to or a consequence of aberrant function of the actin cytoskeleton. The results reveal that formation of Hirano bodies is not necessarily related to cell death. These cultured cell models should facilitate studies of the biochemistry, genetics and physiological effects of Hirano bodies.
Synthesis and secretion of growth hormone in the rat anterior pituitary: II. properties of the isolated growth hormone storage granules
Authors: Howell S. L. , Ewart R. B. L.
Published: April 2021

Partially purified storage granule fractions obtained from rat anterior pituitaries have been utilized to study some properties of the isolated growth hormone granules during incubation in vitro. The isolated granules showed optimal stability at room temperature in the pH range 5·5-6·5 and dissolved progressively with time at a rate which was unaffected by the presence of EDTA, EGTA, ouabain, magnesium ions, or by resuspension in hypotonic media. However, the granules were partially stabilized by the presence of calcium, tyramine or adenosine phosphates ; ATP was most effective of the agents tested and induced almost complete stability. Agents known to stimulate the secretion of growth hormone from the intact cells, cyclic 3′,5′-AMP, dibutyryl cyclic 3′,5′-AMP, theophylline or high potassium concentrations, were each without significant effect on the isolated granules. The granule fraction was ineffective in degrading added 125I-growth hormone over a pH range of 4·5-8·5 and was unable specifically to bind exogenous 125I-growth hormone. Further experiments to elucidate a possible cytological role of nucleotides in stabilization of growth hormone during storage granule formation demonstrated that adenine nucleotides were not constituents of the isolated granules, nor were they secreted into the incubation medium concomitantly with growth hormone. Depletion of intracellular ATP levels has previously been shown to prevent the formation of growthhormone storage granules, and it is suggested that one role of the nucleotide may be to facilitate the formation and stabilization of storage granules in the Golgi complex by interacting with the growth hormone to induce its precipitation.
Electrokinetic characterization of two ascites tumours: TA3 and M.Mel. 1
Authors: Roeder Claudia , Cook G. M. W. , Haemmerli Gisela , Sträuli P.
Published: April 2021

The electrokinetic surfaces of cells of the TA3 ascites tumour of the mouse and the M.Mel. 1 ascites tumour of the golden hamster have been studied for the past 3 years. It became evident that with regard to their electrophoretic mobility (E.P.M.), TA3 cells were stable and melanoma cells were not. Therefore, results discussed in this paper only refer to the melanoma ‘subline’ used for the present investigation. A comparison of the electrokinetic properties of the 2 tumours gives the following information: 1. TA3 and M.Mel. 1 cells have similar E.P.M.s: —103 and — 1·05/ffli s−1 V−1 cm, respectively. 2. Treatment with 15 % formaldehyde raises the E.P.M. of TA3 cells by 18% and of M.Mel. 1 cells by 11%. 3. Incubation with neuraminidase lowers the E.P.M. of TA3 cells by 46 % and of M.Mel. 1 cells by 24%. 4. Consecutive treatment with formaldehyde/neuraminidase and with neuraminidase/formaldehyde produces identical pH-mobility profiles for TA3 and M.Mel. 1 cells. Further, the electrokinetic data suggest that in addition to anionogenic groups, cationogenic groups are present on the surfaces of both TA3 and M.Mel. 1 cells.

Mitotic indices and E.P.M.s of standard washed and neuraminidase-treated M.Mel. 1 cells, examined on consecutive days after implantation, indicate a continuous loss of sialic acid from the electrokinetic surface during the progress of a transplantation passage.

These results are discussed with regard to the significance attributed to ionogenic groups at the surface of normal and neoplastic cells by other authors.
Differences in ploidy and degree of intercellular contact in differentiating and non-differentiating sycamore calluses
Authors: Wright K. , Northcote D. H.
Published: April 2021

Comparisons have been made between a sycamore callus (S4) isolated in 1970 and one first isolated in 1958 (S2). Incubation of S4 on media containing different concentrations of auxin and kinetin showed that the ratio of the hormones was the factor which controlled the growth pattern within the tissue. High ratios of auxin: cytokinin favoured a white friable tissue, whereas a compact callus with a much harder texture was formed at low ratios. Roots were differentiated at intermediate values.

Callus (S2) has not been induced to undergo cellular differentiation. No soluble factors which were capable of stimulating differentiation in S2 were produced during the differentiation of S4, and S2 did not affect the ability of S4 to form roots.

Divisions seen in suspension cultures of S4 callus were mainly diploid; the cells of S2 were predominantly tetrapioid. When S2 suspensions were grown in the cytokinin-free medium used for S4 a considerable number of diploid cells were seen. A number of S2 clones have been isolated and all these developed chloroplasts on exposure to continuous light and, when grown on the medium used to induce differentiation in S4, five of them showed a growth pattern in which the cells were more closely packed than is usually the case in S2 callus.

A greater degree of cell contact has also been induced by including polyethylene glycol in the medium and so restricting the availability of water to the callus. Under these conditions the cells must have a greater capacity for interaction with one another. The effect of tissue texture on the extent of cell contact and adhesion between the cells is discussed in relation to the composition of the plant cell wall and ideas on the totipotency of plant tissue cultures.
An electron-microscope study of the extranucleolar bodies during growth of the oocyte in the prepubertal mouse
Authors: Chouinard L. A.
Published: April 2021

The dictyate nucleus of the growing mouse oocyte exhibits, besides the nucleolus, 3 ultrastructurally distinct types of smaller formed entities referred to as extranucleolar bodies. The extranucleolar bodies of the first type (fibrillogranular bodies) consist of intermingled masses made up of closely arranged convoluted fibrils, 6-10 nm in width, interspersed with electrondense granules approximately 15 nm in diameter. The extranucleolar bodies of the second type (fibrillar bodies) are composed of an entanglement of loosely arranged convoluted fibrils 4-10 nm in diameter; such bodies are also characterized by the presence within their mass of irregularly shaped widely scattered islands of varying sizes made up of densely packed fibrillar material exhibiting a somewhat greater electron opacity. The extranucleolar bodies of the third type (coiled bodies) appear to consist of an aggregate of highly contorted threads, the thickness of which varies from 20 to 35 nm; the threads themselves are composed of bundles of fibrils 5 nm thick which are irregularly twisted along their axis.

An attempt is made to interpret these morphological findings in the light of current knowledge concerning the architectural and functional organization of the oocyte nucleus in general during the protracted dictyate stage of meiotic prophase. Our observations would be consistent with the view that the various types of extranucleolar bodies are morphological expression - like the puffs of the polytene and the loops or spheroids of the lampbrush chromosomes - of differential gene activity on the part of the localized regions of the chromosomes during oocyte growth.
Comparative isolation of cilia and flagella from the lamellibranch mollusc, Aequipecten Irradians
Authors: Linck R. W.
Published: April 2021

Gill cilia and sperm flagella from the lamellibranch mollusc Aequipecten irradians were compared with respect to their ultrastructures and adenosinetriphosphatase activities. Cilia were isolated from excised gills using 3 different solutions: twice-concentrated seawater, 10% ethanol–10 mM CaCl2 and 60% glycerol. In each case deciliation occurs by the severance of the cilium at the junction of the transition zone and the basal body, and in each case the ciliary ultrastructure is maintained. Sperm flagella were purified by mechanical decapitation. Cilia and sperm flagella have similar fine structures, except that the matrix of the cilia contains substantially more electron-dense material than that of flagella. The ATPase activity of purified cilia is approximately 0·09 μmol P1min/mg protein; that of flagella is 0·13. Ciliary and flagellar axonemes were prepared by repeated extraction of the membranes with 1 % Triton X-100. Ciliary axonemes maintain their 9 + 2 cylindrical orientation, whereas flagellar axonemes often appear as opened or fragmented arrays of the 9 + 2 structure, due to the partial breakdown of the flagellar nexin fibres. A-subfibre arms which were obvious in whole organelles are rarely seen in axoneme preparations. Again the ciliary matrix is considerably more amorphous than in flagellar axonemes. The ATPase activities of ciliary and flagellar axonemes are 0·13 and 0·12 μmol P1/min/mg protein respectively; however, activities of ciliary axonemes may vary by a factor of 2, depending on the method of isolation. The difficulty in observing A-subfibre arms in cross-sections of ciliary and flagellar axonemes is discussed in terms of random, non- reinforcing arrangements of the dynein arms.
Identification of a heat-inducible novel nuclear body containing the long noncoding RNA MALAT1
Authors: Onoguchi-Mizutani Rena , Kirikae Yoshitaka , Ogura Yoko , Gutschner Tony , Diederichs Sven , Akimitsu Nobuyoshi
Published: April 2021

The heat-shock response is critical for the survival of all organisms. Metastasis-associated long adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA localized in nuclear speckles, but its physiological role remains elusive. Here, we show that heat shock induces translocation of MALAT1 to a distinct nuclear body named the heat shock-inducible noncoding RNA-containing nuclear (HiNoCo) body in mammalian cells. MALAT1-knockout A549 cells showed reduced proliferation after heat shock. The HiNoCo body, which is formed adjacent to nuclear speckles, is distinct from any other known nuclear bodies, including the nuclear stress body, Cajal body, germs, paraspeckles, nucleoli and promyelocytic leukemia body. The formation of HiNoCo body is reversible and independent of heat shock factor 1, the master transcription regulator of the heat-shock response. Our results suggest the HiNoCo body participates in heat shock factor 1-independent heat-shock responses in mammalian cells.
Emerging evidence for kindlin oligomerization and its role in regulating kindlin function
Authors: Bu Wenting , Levitskaya Zarina , Tan Suet-Mien , Gao Yong-Gui
Published: April 2021

Integrin-mediated cell–extracellular matrix (ECM) interactions play crucial roles in a broad range of physiological and pathological processes. Kindlins are important positive regulators of integrin activation. The FERM-domain-containing kindlin family comprises three members, kindlin-1, kindlin-2 and kindlin-3 (also known as FERMT1, FERMT2 and FERMT3), which share high sequence similarity (identity >50%), as well as domain organization, but exhibit diverse tissue-specific expression patterns and cellular functions. Given the significance of kindlins, analysis of their atomic structures has been an attractive field for decades. Recently, the structures of kindlin and its β-integrin-bound form have been obtained, which greatly advance our understanding of the molecular functions that involve kindlins. In particular, emerging evidence indicates that oligomerization of kindlins might affect their integrin binding and focal adhesion localization, positively or negatively. In this Review, we presented an update on the recent progress of obtaining kindlin structures, and discuss the implication for integrin activation based on kindlin oligomerization, as well as the possible regulation of this process.
Enrichment of Zα domains at cytoplasmic stress granules is due to their innate ability to bind to nucleic acids
Authors: Gabriel Luisa , Srinivasan Bharath , Kuś Krzysztof , Mata João F. , João Amorim Maria , Jansen Lars E. T. , Athanasiadis Alekos
Published: April 2021

Zα domains recognize the left-handed helical Z conformation of double-stranded nucleic acids. They are found in proteins involved in the nucleic acid sensory pathway of the vertebrate innate immune system and host evasion by viral pathogens. Previously, it has been demonstrated that ADAR1 (encoded by ADAR in humans) and DAI (also known as ZBP1) localize to cytoplasmic stress granules (SGs), and this localization is mediated by their Zα domains. To investigate the mechanism, we determined the interactions and localization pattern for the N-terminal region of human DAI (ZαβDAI), which harbours two Zα domains, and for a ZαβDAI mutant deficient in nucleic acid binding. Electrophoretic mobility shift assays demonstrated the ability of ZαβDAI to bind to hyperedited nucleic acids, which are enriched in SGs. Furthermore, using immunofluorescence and immunoprecipitation coupled with mass spectrometry, we identified several interacting partners of the ZαβDAI–RNA complex in vivo under conditions of arsenite-induced stress. These interactions are lost upon loss of nucleic acid-binding ability or upon RNase treatment. Thus, we posit that the mechanism for the translocation of Zα domain-containing proteins to SGs is mainly mediated by the nucleic acid-binding ability of their Zα domains.

This article has an associated First Person interview with Bharath Srinivasan, joint first author of the paper.
Some Effects of Unilateral Ovariotomy in Rabbits
Authors: Asdell S. A.
Published: April 2021

A number of rabbits were partly ovariotomotised, the quantity of ovarian material removed being from one-half to five-sixths of the total present. These operations were performed before puberty.

On breeding, the size of litter was found to be little smaller than that of control rabbits living under the same conditions.

The number of eggs shed by the operated rabbits is but little different from that shed by the controls, suggesting that the basis of fecundity is to be found in somatic conditions rather than in the quantity of oöcytic material present.

The incidence of fœtal atrophy is greater in operated rabbits than in controls. Reasons are advanced in support of the view that the cause of this increased atrophy is different from that prevailing in normal rabbits. Normally, uterine accommodation is not a limiting factor in fertility, or in the size of young born.

Hypertrophy of the remaining ovarian tissue occurs to a varying degree, and is proportionately the greater as more ovarian material is removed. This is probably due to the tendency to produce a definite number of ripe follicles at any one time. No hypertrophy of interstitial material could be detected.

Ova are unable to travel from one uterine horn to the other across the vagina, though migration across the body cavity does occur.

Unilateral ovariotomy does not affect the sex ratio of offspring in rabbits.
Studies on Internal Secretion III.—The Action of Pituitary Extract and Adrenaline on Contractile Tissues of Certain Invertebrata
Authors: Hogben Lancelot T. , Hobson A. D.
Published: April 2021

The action of adrenaline and pituitary extract has been studied on the isolated heart of the crab Maia, the perfused heart of the bivalve Pecten, the isolated crop of the Gasteropod mollusc Aplysia, and the isolated pharynx of the annelid Aphrodite. Methods for the study of the physiology of rhythmical contraction in these invertebrate preparations are described. Pituitary extract in quantities comparable with those which excite the mammalian uterus was not found to have any action on invertebrate muscle. Adrenaline (and epinine) in all cases produced a very pronounced increase in tone accompanied (in Maia, Aphrodite, and Pecten) with acceleration of the normal rhythm. The specificity of the oxytocic action of pituitary extract and the parallelism between the action of adrenaline and of sympathetic excitation in vertebrates are discussed.
On Phosphorus Metabolism in Embryonic Life
Authors: Baldwin Ernest , Needham Dorothy Moyle
Published: April 2021

Estimations have been made of the content of creatine phosphate and inorganic phosphorus in the chick embryo from the 70th to the 360th hour of incubation. The inorganic phosphorus in per cent, of the body weight rises gradually until the 240th hour, at which time there is a sudden and enormous increase, due to ossification of bone. Creatine phosphate was found to be present at the earliest stage investigated. In per cent, of the body weight it rises up to the 4th day and then slowly falls off. At the 4th day there is also a maximum in the phosphagen considered as per cent, of the inorganic plus labile phosphorus. The significance of these results, especially in connection with the existing data on the appearance of muscular movements, is discussed in the text.
The Manner of Sperm Entry in Various Marine Ova
Authors: Chambers Robert
Published: April 2021

This paper is a record of observations on insemination in five species of marine forms, Arbacia punctulata (sea urchin), Woods Hole, Mass., Paracentrotus (Strongy-locentrotus) lividus (sea urchin), Villefranche-sur-Mer, Echinachnius panna (sand-do liar), Mt Desert Island and Woods Hole, Cerebratutus lacteus (nemertine), Mt Desert Island and Woods Hole, and Nereis Embata (annelid), Woods Hole. The observations on all except the European species were made at different times during several summers.
The Mechanism of Projection of the Chameleon’s Tongue
Authors: Zoond A.
Published: April 2021

The projection of the chameleon’s tongue constitutes a unique problem in muscular organisation. It has frequently been recorded that a chameleon can project its tongue to a distance as great, or slightly greater than the length of the animal’s body from nose to anus, and that projection takes place with instantaneous rapidity. Various theories have been advanced to explain this remarkable mechanism, yet still it remains imperfectly understood. The variety of the explanations offered is clearly due to the fact that investigation of this problem has been entirely anatomical, and that no attempt has hitherto been made to apply the test of experiment to it Such an experimental investigation forms the subject of this paper. The experiments here described deal with the tongue, the hyoid apparatus and the accessory muscles, and permit of the formulation of a complete account of this highly complicated and highly perfected response.
Metabolic Changes Associated with Endocrine Activity and the Reproductive Cycle in Xenopus Laevis
Authors: Shapiro H. A. , Zwarenstein H.
Published: April 2021

A new micro-method for the estimation of serum calcium requiring only 0.4 c.c. serum is described. Castration causes a persistent fall (17–34 per cent.) in the calcium content of the serum in females of Xenoput laevis as soon as a months after operation. In males there is no effect 312 months after castration but a foil (16 per cent.) 6 months after. Removal of the anterior lobe (i.e. pars anterior and pars tuberalis) of the pituitary leads to a significantly lower calcium level than removal of the entire gland. Injection of antuitrin into completely hypophysectomised animals causes a rise, injection of pituitrin a foil in serum calcium. Injection of antuitrin into normal animals leads to maximal contraction of melanophores on a black background and injection of pituitrin into normal or completely hypophysectomised toads causes maximal expansion on a white background. When the pars tuberalis regenerates the serum calcium returns to normal concomitantly with the reappearance of the white background response, but without regeneration of the ovaries. The influence of the pituitary on ovarian activity and its effect on serum calcium are. concomitant but independent activities. It is suggested that the pars tuberalis and the posterior lobe have antagonistic effects on both colour change and serum calcium, and that the pars anterior and the posterior lobe exert antagonistic influences on ovarian activity. It is further suggested that the pituitary directly controls ovarian activity, but that both the pituitary and the gonads control calcium metabolism through some other endocrine gland.
Growth Stimulation of Blow-Fly Larvae Fed on Fatigued Frog Muscle
Authors: Fox H. Munro , Smith G. Pugh
Published: April 2021

Blow-fly larvae were fed on (1) resting, and (2) fatigued frog muscle. The larvae fed on fatigued muscle attained a body weight 9 per cent greater than those fed on resting muscle, and the rate of their heart beat was increased by 14 per cent The length of larval life and the oxygen consumption was the same in the two sets of larvae.
The Survival of the Spermatozoon in the Domesticated Fowl
Authors: Walton Arthur , Whetham E. O.
Published: April 2021

In the large majority of animals which have internal fertilisation the effective length of life of the spermatozoon within the body of the female is extremely short. In no mammal is it known to extend from one oestrous period to another. A certain number of more exact determinations have been made. In rabbits, for example, fertilising capacity is retained for about 30 hours (Hammond and Asdell, 1926), and in sheep fertility diminishes presumably from death of the spermatozoa about 27 hours after mating (McKenzie and Phillips, 1930). Data on the survival of motility, which it is to be supposed coincides approximately with fertilising capacity, has been collected by Hammond and Marshall (1925, chap. 6) and Yochem (1930), and the latter found 41 and 17 hours’ survival in the uterus of the guinea pig and rat respectively. However, there are also many known instances of long survival, especially in the invertebrates. In the queen bee, for example, sperm may be stored 7 years and still retain its fertilising power (Bishop, 1920; Courrier, 1921), and in other Hymenoptera spermatozoa may be stored during hibernation or throughout the whole period of egg-laying. Many invertebrates have spermathecae in which spermatozoa are stored presumably for considerable periods. Among the vertebrates prolonged survival is much less common. Some teleosts which have internal fertilisation store spermatozoa for long periods (van Oôrdt, 1928). In some bats, which have their mating season in the autumn and in which the follicles do not ripen till the following spring, the spermatozoa remain alive within the female during the winter (Courrier, 1924; Redenz, 1929). In the male mammal spermatozoa may also be stored for a considerable time in the epididymus (Benoit, 1925, 1926 ; Hammond and Asdell, 1926; Redenz, 1924, 1925, 1926; Young, 1929, 1929 a, 1931). In all these cases of long survival the spermatozoa are stored under what are probably very favourable conditions, of which perhaps the most important is the dense concentration of the sperm-suspension. This is universally characteristic. It has long been known that spermatozoa survive better in concentrated suspension (Gemmill, 1900; Cohn, 1918). Gray (1928, 1928 a, 1931) provides the most likely explanation, having shown for the sea-urchin that dilution activates the sperma-tozoon and that the rate of senescence is an inverse function of the activity.
On the Control of the Level of Activity of the Animal Body
Authors: Carter G. S.
Published: April 2021

Hibernation and the other seasonal variations of activity in the vertebrate have been the subject of a very large amount of investigation and of an even larger literature. This has been recently summarised by Pocock (1926) from the standpoint of general biology, and by Gorer (1931) from that of comparative physiology. Here, it is only necessary to discuss previous work on those aspects of the subject with which this paper is immediately concerned.
Ion Concentration and Activity in the Haemolymph of Aedes Aegypti Larvae
Authors: Edwards H. A.
Published: April 2021

The ionic composition of the haemolymph was measured in fourth instar larvae of Aedes aegypti (reared in 0–30% sea water, the animals’ natural salinity range). Inorganic ions and free amino acids form a substantial part of the haemolymph osmotic concentration. With increasing external osmotic pressure, there is an increase in the concentration of the amino acids, not the major inorganic cations.

Measurements with ion-selective electrodes indicate that the activities of sodium, potassium and chloride can vary independently of their total concentration. The osmotic contribution of these inorganic ions is therefore not necessarily determined by their total concentration.
Peripheral Influences On the Movement of the Legs in A Walking Insect Carausius Morosus
Authors: Cruse H. , Epstein S.
Published: April 2021

Anterior extreme position (AEP) and posterior extreme position (PEP) of the legs of stick insects were measured during walking on a treadwheel or on a slippery glass plate. In several experiments, either protraction or retraction of a middle or hind leg was interrupted. The AEP of other legs was independent of a protraction interruption but PEP was displaced backward in the leg anterior to the interrupted leg. When a leg was standing on a fixed platform (interruption of retraction) no changes were found in AEP and PEP for the other legs but if the platform was slowly moved, PEP of leg on the platform was moved forward. These results disagree with several published hypotheses. The results suggest the hypothesis of a position-dependent threshold value for protraction which is modulated by co-ordinating influences from other legs.
Volumes of the Respiratory and Circulatory Systems in Tufted and Mallard Ducks
Authors: Keijer E. , Butler P. J.
Published: April 2021

Tufted ducks habitually dive for their food and may remain submerged for up to 40 s. Mallards, on the other hand, merely upend themselves for_ a few seconds when dabbling. It was decided, therefore, to determine the size of the oxygen storage compartments in these two aquatic birds. Haemoglobin concentration, blood volume, and volume of the respiratory system are all significantly larger in the tufted duck than in the mallard. Myoglobin concentration in the pectoral and leg muscles of the tufted duck is similar to that in the locomotory muscles of terrestrial birds and mammals. Amounts of usable oxygen (at STPD) stored in the body were calculated to be 41·5 ml kg−1 for tufted ducks and 29·0 ml kg−1 for mallards.
Stimulation of Oxygen Consumption With Fluid Absorption in Insect Recta
Authors: Houlihan D. F. , Sell D.
Published: April 2021

The oxygen consumption of excised abdomens of cockroaches and locusts has been measured before and after the injection of fluids into the ligated recta. Fluid injection caused a transient stimulation of oxygen consumption of up to 30% of the resting rate. The extra amount of oxygen consumed is positively correlated with the osmolality of the fluid injected and the amount of fluid absorbed. Parallel experiments were carried out on the time course of fluid uptake ; these experiments revealed a correlation first between a rapid increase in fluid absorption and stimulation of oxygen consumption, and secondly between the final resting rate of oxygen consumption and a slower absorption of fluid. Locusts take up fluid at double the rate of cockroaches and have double the stimulation in oxygen consumption following fluid injection. In locusts the increases in oxygen consumption can also be correlated with the net movement of Na+, K+ and Cl− from the rectum. The stimulation of oxygen consumption during fluid uptake is discussed in relation to the local osmosis model for fluid uptake.
The Morphology and Passive Electrical Properties of Claw Closer Neurones in Snapping Shrimp
Authors: Wilson John A. , Mellon Deforest
Published: April 2021

The morphology and passive electrical properties of the dimorphic pincer and snapper claw closer neurones were examined in the snapping shrimp, Alpheus heterochelis. No differences were found between homologous pincer and snapper neurones for input resistance and length constant in the proximal portion of the axons, or for the proximal axonal and dendritic anatomies using intracellular cobalt staining. To determine the effect of cell body size upon the passive electrical properties of the neurones, we modelled the neurones by computer. The difference in cell body size causes less than a 3 % change in the electrical properties of the neurone at the axon root. Thus, despite the striking behavioural dissimilarities between the pincer and snapper claws, there is no electrical or morphological basis in the claw closer neurones for this difference.
Acoustic Transmission Through the Head of the Common Mole, Talpa Europaea
Authors: Coles R. B. , Gower D. M. , Boyd P. J. , Lewis D. B.
Published: April 2021

Cues for directional hearing in mammals are traditionally based on inter-aural intensity differences (IIDs) established as a result of the diffraction of a progressive sound wave by the head and pinna, or on inter-aural time differences (ITDs) established because of the separation of the two ears in space. This ‘dual hypothesis’ has been extended to other animal groups despite the fact that the majority of submammalian animals have head dimensions that are small relative to the wavelengths of the sounds used in communication. Under these conditions, little if any diffraction can occur and time differences become very small. As an alternative to the pressurereceiver principle of the mammalian ear, crickets (Michelsen, 1979) and the quail (Coles et al. 1980) use the pressure-difference principle for directional hearing. In a pressure-difference receiver, sound has access to both surfaces of the tympanic membrane (TM) because of an air-filled cavity between the ears which allows sound transmission through the head or body. When the sound pressure level (SPL) acting on the inner surface of the TM is equivalent to that acting on the external surface, the response of the TM (and, therefore, the cochlea) will be determined by the phase difference between the external and internal components. At any one frequency this phase difference will, in turn, vary with the angle of incidence of the sound.
A Comparison of CO2 Excretion in A Spontaneously Ventilating Blood-Perfused Trout Preparation and Saline-Perfused Gill Preparations: Contribution of the Branchial Epithelium and Red Blood Cell
Authors: Perry Steve F. , Davie Peter S. , Daxboeck Charles , Randall David J.
Published: April 2021

A spontaneously ventilating blood-perfused trout preparation and saline perfused gill preparations were utilized to investigate the role of the erythrocyte and branchial epithelium in CO2 excretion and acid-base regulation. CO2 excretion blood-perfused preparations was positively correlated with haematocrit (Het), and was abolished completely during plasma-perfusion. Elevating HCO3− concentration of input blood from 10 to 25 mm significantly increased , fourfold in blood-perfused preparations as a result of increased entry of HCO3− into the red blood cell and not into the gill epithelium. Increased HCO3− concentration was without effect in totally saline-perfused coho salmon (Onchorynchus kisutch). The addition of 4-acetamido-4′-iro-thiocyanatostilbene-2,2′ disulfonic acid (SITS; 10−4 M) to input blood significantly reduced and oxygen uptake in blood-perfused fish due to inhibition of erythrocytic HCO3Ȓ/Cl −exchange. Unlike blood-perfused preparations, no saline-perfused preparation (isolated holobranchs or totally perfused rainbow trout or coho salmon) displayed measureable CO2 excretion at physiological and pH. Increased input in both blood-perfused and saline-perfused preparations significantly increased due to enhanced branchial diffusion of molecular CO2. It is concluded that the entry of HCO3− into the erythrocyte is the rate-limiting step in CO2 excretion and that movement of HCO3− from plasma to gill epithelium cells in no way contributes to overall CO2 elimination.
Physiological Response to Acid Water in Brown Trout (Salmo Trutta L.): Cell Volume Regulation in Heart Ventricle Tissue*
Authors: Fugelli Kjell , Vislie Tone
Published: April 2021

In brown trout surviving in acidified brook water, the plasma osmolality is reduced 15–25%. The decrease is much less than that expected from the measured reduction in the plasma concentration of Na+ and Cl−. This discrepancy cannot quantitatively be explained by the increase in plasma concentration of K+ (100%) and free amino compounds (mainly taurine; 280%) but appears mainly attributable to a reduction in plasma volume.

The osmolality of heart ventricle cells is also reduced. Water content of the cells is unchanged, and there is a significant decrease in the intracellular concentration of K+, taurine and to a lesser extent glutamic acid, accounting for 25, 45 and 8%, respectively, of the osmolality reduction. These findings indicate the existence of a cell volume regulation mechanism in the fresh water brown trout which counteracts osmotic swelling of tissue cells during periods of salt loss in acidified water. The significance of this mechanism for survival under such conditions is discussed.
Speed, Acceleration and Manoeuvrability of Two Teleost Fishes
Authors: Webb P. W.
Published: April 2021

Speed, acceleration rate and turning radius were measured for rainbow trout (Salmo gairdneri length 25·7 cm) and smallmouth bass (Micropterus dolomieu; ength 23· 6 cm) attacking live minnows. The observations sampled a range of values for each kinematic variable up to the limits of maximum performance. Minimum turning radius was independent of speed and acceleration rate. Expressed as a ratio of total length, L, minimum radii were 0·18 ± 0·2L for trout and 0·11 ± 0·02L for bass . Differences in minimum turning radius, R, between trout and bass were attributed to differences in the volume of the body and entrained water, V, and projected lateral surface area of the body and median fins, A. For subcarangiform swimmers, the dimensionless minimum specific turning radius R/L = 2V/AL. Since V is numerically equal to the mass of the body, M, and added water mass (approximately 0·2M) for neutrally buoyant fish, R/L can be calculated from two easily measured morphological parameters, M and A.
The Interaction of Environmental Calcium and Low pH on the Physiology of the Rainbow Trout, Salmo Gairdneri
Authors: McDonald D. G.
Published: April 2021

Exposure of adult rainbow trout to low pH (pH 4·3) in soft water (Ca2+ = 223 μequiv/1) caused a substantial ionic disturbance which arose primarily because of large net losses at the gills. In contrast, renal ion losses were low initially and declined even further because of a pronounced reduction in urine flow. A net influx of H+ occurred across the gills but this was not sufficient to cause a blood acid-base disturbance or a renal response. Although branchial ion and H+ fluxes declined with time, blood ion levels did not return to normal and many of the fish died. Further reduction in water calcium (Ca2+ = 69 μequiv/1) provoked a higher mortality and a more substantial ionic imbalance. These results contrast sharply with the effects on trout of acid exposure in hard water (Ca2+ ⩾ 1600μequiv/l), where net ion losses and mortality are reduced and H+ uptake increased. A preliminary model for the interaction of low pH and calcium is proposed and evidence for adaptation to acid stress and for the origin of acid lethality is discussed.