bluuebunny/crossref_metadata_2025 huggingface dataset:
Regrowth of amputated velvet antlers with and without innervation
Authors: Suttie J. M. , Fennessy P. F.
Published: June 2005

The influence of removing portions of the growing antler of yearling red deer stags on subsequent regeneration of the antler in the same season was studied. The influence of the innervation of the antler on such regeneration was the subject of a further study. When the top 0.5–1 cm was removed from antlers 9–17 cm long, growth was slightly reduced in that season. When the antler/pedicle length was reduced to 6–10 cm in antlers 16–38 cm long, branched antlers regrew in 11 out of 13 cases provided the amputation was carried out early in the growing season, i.e., before mid‐December. Denervated antlers were shorter, lighter, and of different shape compared with controls, but they were of similar density. Denervation was confirmed histologically. Cleaning of velvet and casting of antlers following castration were unaffected by denervation. It would appear that although nerves affect the size and shape of the antler, they are not essential to the actual control of antler growth and regeneration.
Necessity of an adequate nerve supply for regeneration of the amputated pectoral fin in the teleost Fundulus
Authors: Geraudie Jacqueline , Singer Marcus
Published: June 2005

The present work deals with the determination of the threshold of nerve fibers per unit of amputation surface necessary for regeneration of the pectoral fins of a teleost, Fundulus. Partial denervation of the amputated pectoral fins, i.e., resection of one or two of the three nerves of the brachial (= pectoral) plexus revealed that the presence of a single one allows the amputated fin to regenerate. From these data and others obtained previously, it is concluded that the nervous requirements for a teleost fin to regenerate are similar or slightly lower than those for tetrapods, for example in the newt, which are capable of appendage regeneration.
Sex determination in Hydra: Roles of germ cells (interstitial cells) and somatic cells
Authors: Campbell Richard D.
Published: June 2005

Germ cells were exchanged between male and female hydra to determine whether the germ cells or the somatic tissues determine the phenotypic sex of the polyp. Interstitial cells, the precursors of gametes, were removed from male and female Hydra oligactis by gamma irradiation. The resulting polyps, termed “epithelial hydra,” possessed the characteristic morphology of H. oligactis, and could reproduce by budding but could not produce gametes. When these epithelial hydra were repopulated with interstitial cells from normal hydra of the same or opposite sex, their sexual phenotypes were those of the interstitial cell donors. These results indicate that the germ cells, rather than somatic cells, determine the phenotypic sex of hydra.
Effects of hexylene glycol and nocodazole on microtubules and melanosome translocation in melanophores of the medaka Oryzias latipes
Authors: Obika Masataka , Negishi Sumiko
Published: June 2005

Melanophores of the medaka Oryzias latipes respond to the stimulation of alpha adrenergic receptors with a rapid centripetal translocation (aggregation) of melanosomes. Preincubation of isolated melanophores in hexylene glycol with or without colchicine results in an inhibition of melano‐some aggregation concomitantly with the disarrangement of the cytoplasmic microtubular framework. Incubation in hexylene glycol at higher concentrations induces structural modification and disassembly of preexisting microtubules, especially in the perinuclear region of the cells. A microtubule inhibitor, nocodazole, also inhibits melanosome aggregation through disruption of micro‐tubules. These results indicate that both the presence of a substantial number of microtubules and their innate arrangement are indispensable for the rapid centripetal translocation of melanosomes. The results also suggest that micro‐tubules undergo cycles of disassembly and reassembly during pigment movement.
Absence of DNA in yolk platelets of Bufo arenarum oocytes
Authors: de Recondo Marta E. Fernández , de Arcuri Beatriz Fernández , Recondo Eduardo F.
Published: June 2005

The absence of DNA in the yolk platelets of Bufo arenarum oocytes was verified. Oocytes from the coelomic cavity were used in order to avoid possible contamination by the ovarian tissue. Four methods for DNA analysis were employed, and the possibility of interference was carefully checked. The presence of three possible contaminants, which produced positive reactions from the DNA analysis, was detected. These were the glycosaminoglycan from the superficial layer of the platelets, sucrose, and polyvinylpyrrolidone from the buffer commonly used during the isolation of platelets.

The present evidence points to the necessity of using at least two different methods for DNA determination with due regard for their sensitivity and specificity before any firm conclusion can be reached on the presence or absence of DNA in nonnuclear and mitochondrial parts of the oocyte.
Electron microscopic analysis of the sperm nuclear changes in meiosis inhibited eggs of the brittle‐star Amphipholis kochii
Authors: Yamashita Masakane
Published: June 2005

This paper describes the sperm nuclear changes in the eggs of the brittle‐star Amphipholis kochii that had been treated with meiosis inhibitors, including the nuclear division inhibitors (colchicine, colcemid, griseofulvin, and vinblastine) and the cytokinesis inhibitor (cytochalasin B), as observed by transmission electron microscopy. In the normal, monospermic fertilization process, the male pronucleus formation consists of two processes: the first dispersion process before formation of the nuclear envelope and the second dispersion process on and after envelope formation. When nuclear division was inhibited, so that the female pronucleus formation was also inhibited, the sperm nucleus incorporated into such eggs decondensed to some extent, in accordance with the first dispersion process, but the nuclear envelope did not form around the nucleus and further decondensation (the second dispersion process) was also inhibited. When cytokinesis was inhibited, the sperm nucleus, as well as the maternal chromosomes, transformed into the pronuclei on schedule. These results suggest that 1) the male pronucleus formation has an intimate relationship with meiosis, especially nuclear division, as well as with the formation of the female pronucleus; 2) the male pronucleus formation consists of at least two different processes, a meiosis‐independent process (the first dispersion process) and a meiosis‐dependent process (the second dispersion process); and 3) the factor for the first dispersion process is a soluble component while the factor for the second dispersion process is membrane associated.
Chicken developmental antigens: Analysis of erythroid populations with monoclonal antibodies
Authors: Trembicki K. A. , Dietert R. R.
Published: June 2005

Fusions were performed between the mouse PAI myeloma cell line and spleen cells from Balb/c mice immunized with intact erythrocytes from 1‐day Cornell K‐strain White Leghorn chickens. Following single cell cloning, four hybridoma clones were found to secrete erythroid specific monoclonal antibodies. Based on its pattern of reactivity, the antibody (IgG2a, κ) secreted by clone 10C6 detects a specific avian oncodevelopmental antigen associated with the hematopoietic system: chicken fetal antigen (CFa). Two other clones, designated as 3F12 and 4C2, produced antibodies (IgM, κ) that recognize another avian developmental antigen: chicken adult antigen (CAa). A fourth clone, 9F9, produced an antibody (IgM, κ) that reacts with all peripheral erythrocytes from both Japanese quail and chicken regardless of age. Clone 10C6 antibody apparently detects an erythrocyte specific (ES) determinant of CFA associated with determinant #8 while antibodies of clones 3F12 and 4C2 recognize a chicken specific determinant of CAA. Analysis by complement mediated microcytotoxicity indicated that the epitopes detected by 10C6 vs 3F12 and 4C2 antibodies were expressed on erythrocytes in a reciprocal fashion during development. Furthermore, strain variations in the incidence of erythrocytes carrying these epitopes were observed. The usefulness of these monoclonal antibodies for the study of erythroid populations is discussed.
Nerve repair and behavioral recovery following brain transplantation in Notoplana acticola, a polyclad flatworm
Authors: Davies Lynnae , Keenan Larry , Koopowitz Harold
Published: June 2005

Although Notoplana acticola, a marine polyclad, cannot regenerate brain tissue, neuronal repair is rapid. Brains were transplanted into decerebrate flatworms to determine the anatomical patterns and functionality of neural connections established between a new brain and the peripheral nerve network of the recipient animal. Sixty‐nine transplants were performed. Four brain transplant orientations were used: normal, reversed, inverted, and reversed inverted. The functionality of the transplanted brains was tested and measured using both behavioral and electrophysiological criteria. Within 23 days, 56% of the transplants that survived and retained the transplants recovered the four behaviors tested: righting behavior, avoidance turning, ditaxic locomotion, and feeding. Nerves exiting the brain tended to join with the peripheral nerves closest to them. Anatomical connections were made within 24 hr of surgery. Some normal behavior was seen within the first 36 hrs after surgery. Control decerebrate worms did not recover behavior. Preliminary intracellular recordings from three types of identified brain sensory interneurons, in transplants, revealed normal electrophysiological properties and this implied that appropriate connections with peripheral sensory cells had been reestablished. Intracellular dye‐marking of these neurons in reverse‐oriented brains revealed that, although individual nerve processes apparently leave the brain and associate with inappropriate nerve cords, some of the processes turn 180° to reinervate nerve cords, which they normally occupy in unoperated animals. Thus, although anatomical and functional neural connections apparently were made rapidly following brain transplantation, the specificity of the reconnections remains to be shown.
Plasma and pituitary prolactin levels in rainbow trout during adaptation to different salinities
Authors: Prunet P. , Boeuf G. , Houdebine L. M.
Published: June 2005

The development of a highly specific radioimmunoassay for salmonid prolactin (PRL) using chinook salmon PRL allowed us to study plasma and pituitary PRL profiles in large sedentary rainbow trout (Salmo gairdneri) transferred from fresh water to seawater and vice versa. Plasma osmotic pressure and chloride levels were also measured for 3 weeks following change of salinity. Within 1 day after transfer to full seawater we observed a plasma PRL decrease, which stayed significantly lower (3–5 ng/ml) than the fresh water control group (10–15 ng/ml) during the entire experiment. Pituitary PRL content showed an initial abrupt increase, but after 3 weeks in seawater pituitary PRL content had decreased to the same level as in the fresh water control group. On the contrary, transfer from seawater to fresh water was followed within 1 day by a rise in plasma PRL levels, which stayed high (10–15 ng/ml) after 3 weeks in fresh water. Simultaneously, pituitary PRL content decreased significantly. These results may indicate an important role of PRL in fresh water adaptation of sedentary rainbow trout.
Studies on the mechanisms of neurulation in the chick: Interrelationship of contractile proteins, microfilaments, and the shape of neuroepithelial cells
Authors: Lee Hsin‐Yi , Nagele Robert G.
Published: June 2005

Electron microscopy and indirect immunofluorescence were employed to correlate the distribution patterns of major contractile proteins (actin and myosin) with 1) the organizational state of microfilaments, 2) the apical cell surface topography, 3) the shape of the neuroepithelial cells, and 4) the degree of bending of the neuroepithelium during neurulation in chick embryos at Hamburger and Hamilton stages 5–10 of development. Both actin and myosin are present at these developmental stages and colocalize in the neural plate as well as in later phases of neurulation. During elevation of neural folds, actin‐ and myosin‐specific fluorescence is always most intense in regions where the greatest degree of bending of the neuroepithelium takes place [e.g., the midline of the V‐shaped neuroepithelium (early neural fold stage) and the midlateral walls of the “C”‐shaped neuroepithelium (mid–neural‐fold stage)]. This intense fluorescence coincides with 1) a particularly dense packing of microfilaments and 2) highly constricted cell apices. After neural folds make contact, there is an overall reduction in both the intensity of apical fluorescence and the thickness of apical microfilament bundles, especially in the roof and floor of the neural tube. The remaining fluorescence in the contact area is apparently related to cellular movements during fusion of neural folds.
Association of maternal and newly synthesized ribosomes with membranous noncytoskeletal structures in Xenopus laevis embryonic cells
Authors: Shiokawa Koichiro , Tashiro Kosuke , Misumi Yoshio
Published: June 2005

In Xenopus laevis embryos a high concentration of both KCl and 0.5% DOC (sodium deoxycholate) is needed for maximal extraction of ribosomes and polysomes. We studied the nature of the structures that keep ribosomes and polysomes immobilized within the cytoplasm of embryonic cells at cleavage through tailbud stages, using various combinations of a low‐salt buffer (20 mM KCl), a high‐salt buffer (500 mM KCl), 0.5% DOC, and 0.5% Triton X‐100. With a low‐salt buffer and 0.5% DOC, but not Triton X‐100, 80S ribosomal monomers and polysomes were liberated from the cytoplasmic rapidly sedimenting structures (RSS) to the soluble fraction. With a high‐salt buffer (500 mM KCl), ribosomes were solubilized as 60S and 40S subunits together with about one‐half of the total polysomes. When cells were homogenized in a low‐salt buffer with added inhibitors of the cytoskeleton (cytochalasin B or colchicine), the majority of polysomes but not ribosomes were solubilized. These results provide evidence for the following conclusions. 1) Polysomes are bound to cytoskeletal structures in Xenopus embryos, but ribosomes, both maternal and newly synthesized, are associated with membranous noncytoskeletal structures. 2) The membranous structures consist of two compartments, one high‐salt sensitive and the other high‐salt resistant. 3) Ribosomes of the high‐salt resistant group increase in amount with developmental stage and appear to be the precursor to the ribosomes of the high‐salt sensitive group.
Inhibition of DNA replication in preimplantation mouse embryos by aphidicolin
Authors: Spindle Akiko , Nagano Hiroshi , Pedersen Roger A.
Published: June 2005

The regulation of trophectoderm differentiation in mouse embryos was studied by inhibiting DNA synthesis with aphidicolin, a specific inhibitor of DNA polymerase alpha. Embryos were exposed to aphidicolin (0.5μg/ml) for 16 h at various preimplantation stages and scored for their ability to form a blastocyst and develop beyond the blastocyst stage. Embryos were most sensitive to aphidicolin at the late 4‐cell stage and became progressively less sensitive as they developed. Aphidicolin inhibited blastocyst formation by 70%, 100%, 77%, and 24% after treatment at the 2‐cell, 4‐cell, noncompacted 8‐cell, and compacted 8‐cell stages, respectively. Although the inhibitory effect of aphidicolin on blastocyst formation decreased markedly as 8‐cell embryos underwent compaction, developmental capacity beyond the blastocyst stage was poor after treatment of either noncompacted or compacted 8‐cell embryos. Treatment at the morula and early blastocyst stages was less harmful to embryos than treatment at earlier stages but reduced the number of trophoblast outgrowths by interfering with hatching. Autoradiographic analysis showed that during aphidicolin treatment, incorporation of 3H‐thymidine was inhibited over 90% at all stages examined, indicating an inhibition of DNA synthesis. Because inhibition of blastocyst formation by aphidicolin decreased at the compacted 8‐cell stage, we suggest that approximately the first half of the fourth DNA replication cycle is critical for subsequent blastocyst formation. Furthermore, the poor further development of blastocysts formed after aphidicolin treatment of compacted 8‐cell embryos suggests that the DNA replication requirements for initial trophectoderm differentiation are distinct from requirements for further development of blastocysts in vitro.
Cytotoxic rejection of xenografts between marine sponges
Authors: Buscema Marco , Van de Vyver Gyséle
Published: June 2005

In order to extend the range of investigations on sponge incompatibility reactions, xenografts were performed underwater between three marine species: the ramose sponge Axinella polypoides and the two encrusting sponges Crambe crambe and Hemimycale columella. The rejection processes were followed using light, transmission electron, and scanning electron microscopy. In both combinations observed—Axinella/Crambe and Axinella/Hemimycale—the xenografts show disorganization of the superficial tissues during the first days of contact and development afterward of a necrotic reaction. The rejection process is characterized by 1) rapidity, strength, and reciprocity of reaction; 2) tissue necrosis of great depth; and 3) restriction of the response to the zone of the contact. Control of reaction specificity was achieved by contact of sponges with some inert materials (PVC foam, glass, cork, and granite). This resulted in various nonnecrotic reactions. The diversity of these reactions, together with the xenograft rejection processes, demonstrates new aspects of discriminative sponge capabilities. Alternative explanations of acute xenograft rejection, involving either killer cells or cytotoxic substances from endogenous or exogenous origin, are discussed.
The distribution of actin in sheep ovaries
Authors: Cran David G. , Musk Linda
Published: June 2005

The distribution of actin in sheep ovaries has been examined using immunofluorescent techniques. The germinal epithelium, which contained abundant microfibrils, fluoresced strongly while the underlying stroma was only weakly positive. During early follicular growth a band of fluorescence was associated with the base of those granulosa cells abutting onto the basal lamina. This transitional polarity of actin distribution was correlated with cell shape changes in the basal granulosa.
Isolation and enzymatic characterization of the plasmalemma from bovine spermatozoa
Authors: Casali E. , Farruggia G. , Spisni A. , Pasquali‐Ronchetti I. , Masotti L.
Published: June 2005

An improved method for the isolation of pure plasma and acrosomal membranes from bull spermatozoa is presented. Plasma membranes were isolated from the spermatozoa of bulls of different breeds, and some enzymatic activity, such as (Na+‐K+) ATPase, Ca++ ATPase, Mg++ ATPase, alkaline and acidic phosphatases were assayed. Such enzymatic activity levels differ noticeably from those published by other authors, whose preparations were probably contaminated by other cellular components. Highly statistically significant differences of these activities have been found among the several breeds.
Cell‐free translation of Drosophila imaginal disc mRNA
Authors: Greenberg Robert M. , Adler Paul N.
Published: June 2005

Total RNA derived from the imaginal discs of Drosophila melanogaster was translated in vitro, and the polypeptide products electrophoresed on two‐dimensional gels. In agreement with previously published examinations of imaginal disc protein synthesis and content, we can detect no reproducible differences in abundant mRNA populations between different disc types (foreleg and wing). Differences can be found, however, between imaginal discs and other tissues. We also present evidence for a nonuniformly distributed wing disc mRNA.
Retention of lateral motor column neurons during the phase of rapid cell loss after limb amputation in Rana pipiens tadpoles
Authors: Kett Nancy A. , Pollack Emanuel D.
Published: June 2005

Target tissue regulation of naturally occurring neuronal death during development has often been studied by removing a limb bud and then analyzing spinal motor neuron number later in development. The present study focuses on the necessity for limb presence in the initiation of the most rapid phase of cell loss from the lateral motor column (LMC) and in the control of neuron number during this restricted developmental period. Unilateral hindlimb amputation in larval Rana pipiens at the time of onset of rapid LMC cell loss resulted in an unequal, bilateral retention of excess motor neurons (i.e., less cell loss than normally occurs) during this phase. Limb traumatization, with axotomy, also resulted in reduced bilateral LMC cell loss, although to a lesser extent than did amputation. Absence of the limb or axonal transection presumably prevents the communication of motor neurons with their differentiating targets and thus interferes with the flow of information required for the selective events of neuronal loss and survival. The presence of the limb with intact axons is essential at the time that LMC cell loss normally ensues for both the initiation and progression of the phase of greatest cell loss.
Sperm motility in the horseshoe crab. V: Zinc removal mediates chelator initiation of motility
Authors: Clapper David L. , Lamothe Paul J. , Davis James A. , Epel David
Published: June 2005

Limulus spermatozoa are nonmotile after dilution into sea water, and motility is initiated in situ by a sperm motility‐initiating peptide (SMI) that emanates from Limulus eggs. In the absence of SMI, several structurally different chelators (EDTA, EGTA, phenanthroline, dipyridyl, cysteine, and dithiothreitol; 1 mM each) initiated sperm motility; and in the presence of SMI, EDTA prolonged the duration of motility initiated by SMI. Of the elements determined to be present in Limulus sperm, Zn+2 (0.1 μM free Zn+2) was both the most effective at preventing EDTA initiation of motility and the only ion to prevent EDTA prolongation of SMI‐initiated motility. 65Zn was concentrated from sea water by Limulus sperm and was rapidly removed by EDTA. These results indicate that removal of the Zn+2 normally associated with Limulus spermatozoa can initiate or enhance motility. However, SMI does not act as a Zn+2 chelator, since SMI removed little 65Zn from the sperm while at the same time initiating motility of greater percentage and duration than did EDTA. The mechanism by which Zn+2 removal enhances sperm motility is not yet known but could involve a Zn+2‐dependent or Zn+2‐regulated step in the pathway of SMI action.
Characterization of molt‐inhibiting hormone (MIH) action on crustacean Y‐organ segments and dispersed cells in culture and a bioassay for MIH activity
Authors: Mattson Mark P. , Spaziani Eugene
Published: June 2005

Ecdysteroid secretion in vitro by gland quarters and dispersed cells of ecdysial glands (Y‐organs) of the crab, Cancer antennarius Stimpson, was characterized. Optimum culture conditions are reported for maximum, sustained (72 hr) secretion and maintenance of cell viability in activated Y‐organs obtained from de‐eyestalked donors. Addition in vitro of eyestalk ganglia extracts containing the putative molt‐inhibiting hormone (MIH) inhibited ecdysteroid production dose‐dependently in the range of 0.1–4.0 and 0.01–4.0 eyestalk equivalents of MIH for gland quarters and dispersed cells, respectively. Inhibition by MIH was reversible, tissue specific as to source of MIH activity, and did not affect cell viability relative to controls. The results of replicate incubations of gland quarters with MIH were analyzed with formal statistics of parallel‐line assay. The inhibitory action on ecdysteroid secretion is shown to be reproducibly linear and parallel in the dosage range, 0.1–4.0 eyestalk equivalents, amenable to calculation of relative potency among successive extracts, and of sufficiently high precision to serve as an MIH bioassay. Also, the results of these studies support the hypothesis that control of Y‐organs by the eyestalks is physiologically direct.
Calcium from extracellular concretions in the gills of freshwater unionid mussels is mobilized during reproduction
Authors: Silverman Harold , Steffens W. L. , Dietz Thomas H.
Published: June 2005

At least 20–60% of the dry weight of unionid gills occurs as inorganic calcium concretions. These concretions are a calcium store mobilized during reproduction. The concretion content in gills of reproductively active animals decreases, as determined by morphological study and chemical isolation. While mobilization is occurring, maternal blood phosphate and bicarbonate remain normal, and calcium declines. These data are consistent with the hypothesis that concretion calcium, from the gills, leaves the maternal animal and may serve as a calcium source for glochidial shell formation in the calcium poor freshwater environment.
Changes in protein synthesis during early cleavage of the Mongolian gerbil embryo
Authors: Norris Michael L. , Barton Sheila C. , Surani M. Azim H.
Published: June 2005

An examination of polypeptide synthesis during early development in the Mongolian gerbil revealed similar protein profiles up to the early 2‐cell stage, and a gradual change over a period of ∼18 h to give a distinctly different profile by the late 2‐cell stage which remained largely unchanged thereafter. The incorporation of [35S] methionine into protein was significantly reduced by the late 2‐cell stage, followed by a marked increase 24 h later. Enucleation of fertilized 1‐cell embryos and culture in vitro resulted in retention of the early 2‐cell profile. These results indicate probable transition from the initial use of stored maternal message before the onset of embryonic gene activity. Comparisons have been made with similar studies in the mouse.
Rana ridibunda varies geographically in inducing clonal gametogenesis in interspecies hybrids
Authors: Hotz Hansjürg , Mancino Giorgio , Bucciinnocenti Stefania , Ragghianti Matilde , Berger Leszek , Uzzell Thomas
Published: June 2005

Diploid F1 hybrids between Rana ridibunda from Adriatic SW Yugoslavia and Polish R. lessonae, and between Polish R. ridibunda and an unnamed species from SW Yugoslavia are shown by electrophoresis and examination of lampbrush chromosomes to contain both parental genomes in their diploid oocytes I. In contrast, central European R. ridibunda genomes in diploid hybrids, whether F1s or from natural hemiclonal lineages, induce exclusion of the lessonae genome in the germ line, only ridibunda translation products and endoreduplicated ridibunda chromosomes being detected in their diploid oocytes I. The data demonstrate geographic variation of R. ridibunda in the ability of its genomes to induce clonal gametogenesis in interspecies hybrids. They also suggest that genomes of the unnamed Yugoslavian species may be resistant to such exclusion.
Dichotomous effects of forskolin on somatic and germ cell components of the ovarian follicle: Evidence of cAMP involvement in steroid production and action
Authors: Kwon Hyuk B. , Schuetz A. W.
Published: June 2005

The role of cyclic AMP (cAMP) in ovarian follicular functions in Rana pipiens was investigated with the use of the adenylate cyclase stimulator, forskolin, which is thought to elevate intracellular level of cAMP. Effects offorskolin on oocyte germinal vesicle breakdown (GVBD) and on progesterone production by the follicles were assessed during the course of in vitro culture. Addition of forskolin to culture medium suppressed both progesterone‐and frog pituitary homogenate (FPH)‐induced meiotic maturation of the oocytes. Inhibitory effects of forskolin were essentially reversible and forskolin completely inhibited GVBD when added during the first four hours of incubation following exposure to progesterone. Forskolin alone stimulated a low level progesterone production by isolated follicles, but markedly stimulated progesterone production when it was supplemented with a low dose of FPH (0.005 pituitary equivalent/ml). Thus, forskolin acts synergistically with FPH on follicle cells to stimulate progesterone production. A higher dose of FPH (0.05 pitui. eq./ml) produced no additional synergistic effect of forskolin. Therefore, forskolin appears to have two contradictory functions in ovarian follicles: it augments FPH induced follicle secretion of meiosis initiator, progesterone, and simultaneously suppresses the maturation of the oocytes triggered by exogenous progesterone or FPH.

The data presented indicate that there are two independent adenylate cyclase systems in the ovarian follicles which have separate functions: one in the follicle cells and the other in the oocyte. The two enzyme systems are thus compartmentalized and regulate different biological functions using the same messenger, cAMP. The data provide evidence that in amphibians, as in mammals, pituitary hormones regulate steroid hormone production by follicle cells via a cyclic AMP system. Thus, control of oocyte maturation induction appears to be determined by the relative levels of cAMP present in the follicle cells and oocytes.
Luminal and basolateral surface membranes of secretory acinar cells: Electrophysiological comparison of cationic sensitivities
Authors: Senseman D. M. , Horwitz I. S. , Cleemann L. , Orkand P. M.
Published: June 2005

Cation sensitivities (K+, Na+, and Ca2+) of luminal and basolateral membrane surfaces of secretory acinar cells were compared using a luminally perfused and externally superfused salivary gland from the aquatic snail, Helisoma trivolvis. Tight junctions delimiting the two membrane surfaces were observed near the acinar lumen suggesting that the total membrane area exposed to the superfusion solution exceeded that in contact with the luminal perfusion solution.

The resting membrane potential of acinar cells was found to be dependent upon the K+ concentration in both the external superfusion and the luminal perfusion solutions. Unilateral K+ elevation at either membrane surface produced a rapid and sustained depolarization of the acinar cell. For a given K+ concentration, the level of depolarization produced by K+ elevation at the basolateral surface was significantly higher than at the luminal surface. The highest level of membrane depolarization was observed following simultaneous K+ elevation at both membrane surfaces.

The ability of acinar cells to generate overshooting action potentials in response to electrical field stimulation was dependent upon both Na+ and Ca2+. Complete blockade invariably occurred following bilateral removal of either cation. The effects of unilateral removal of either Na+ or Ca2+ proved to be somewhat variable. In general, unilateral removal of Na+ was more effective in reducing the regenerative response than Ca2+ while removal of either cation from the basolateral surface was more effective in reducing the regenerative response than its removal from the luminal surface.

Electrically evoked action potentials in acinar cells could also be blocked with unilateral application of the Ca2+ antagonist, cadmium (Cd2+), at either membrane surface. However, higher Cd2+ concentrations were required to achieve complete blockade when applied to the luminal than to the basolateral gland surface. This result fails to support a hypothesis of voltage‐sensitive Ca2+ channels being spatially restricted to the luminal cell surface in this preparation.
Changes in the rate of translation with reactivation of delayed implanting mouse embryos
Authors: Weitlauf H. M.
Published: June 2005

The transient embryonic diapause associated with delayed implantation in mice is characterized by decreases in the rates of synthesis of RNA and protein as well as a cessation of development. The present experiments were undertaken to examine the possibility that controls on protein synthesis at the level of translation of mRNA provide a regulatory mechanism in this situation. Rates of peptide chain elongation were determined in dormant embryos as well as in embryos that were reactivated either in vivo by estradiol‐17β or by incubation in vitro. In dormant embryos the rate of peptide elongation was found to be approximately half that in active embryos. Although this change in translational efficiency appears to be sufficient to account for previously observed differences in overall rates of protein synthesis in dormant and reactivated embryos, the possibility that some changes also occur at the level of transcription during reactivation is not ruled out.
Unusual responses of cultured Fundulus heteroclitus melanophores to epinephrine and lons, paradox of K+ versus Na+
Authors: Clark Carl R. , Taylor John D. , Tchen T. T.
Published: June 2005

Fundulus heteroclitus melanophores were successfully cultured and maintained in culture for up to 2 months. Compared to other teleost melanophores in the fin, scale, or split fin preparation, the cultured melanophores show unusual responses to both epinephrine and ion solutions. First, they aggregated their melanosomes in response to concentrations of epinephrine as low as 10−12M. Second, the melanophores in a 6‐day, or older, culture aggregated their melanosomes in response to both sodium and potassium ion solutions. This is in contrast to 4‐day‐old cultures (and reports of noncultured melanophores) where melanosomes are aggregated in response to potassium but dispersed in sodium ion solutions.
Anaerobic aspartate metabolism and the formation of alanine in molluscan cardiac muscle: A 13C Nmr study
Authors: Graham R. A. , Ellington W. R.
Published: June 2005

Carbon nuclear magnetic resonance (13C‐NMR) spectroscopic techniques were used to investigate the metabolism of (13C‐3>)‐aspartate and (13C‐4>)‐aspartate by in vitro preparations of the ventricle of the whelk Busycon contrarium. Under anoxic conditions, there was substantial conversion of (13C‐4>)‐aspartate to C‐1,4 succinate with no detectable enrichment of other compounds. When (13C‐3>)‐aspartate was the substrate, there was substantial enrichment of C‐2,3 succinate. However, there was no detectable enrichment of the C‐2 or C‐3 positions of alanine. This finding suggests that the direct transfer of carbon from aspartate to alanine is minimal under anoxic conditions in whelk ventricle. Thus, the malic enzyme may not be functional in the decarboxylating direction under these conditions.
Modification of cardiac activity in response to dehydration in the terrestrial slug, Limax maximus
Authors: Grega Debra S. , Prior David J.
Published: June 2005

The level of body hydration in the terrestrial slug Limax maximus modifies several aspects of behavior such as pneumostome activity, feeding responsiveness, huddling, and contact‐rehydration. The relationship between water balance and pneumostome activity and respiratory function suggested that cardiac activity might also be affected. To pursue this possibility, intact slugs and isolated heart‐central nervous system (CNS) preparations were used to investigate cardiac responses to the increase in hemolymph osmolality which occurs during dehydration. In intact animals, heart rate increased in response to progressive air‐dehydration and to increases in hemolymph osmolality resulting from injections of hyperosmotic solutions of mannitol or NaCl. In isolated preparations, the heart or CNS were separately exposed to hyperosmotic saline. Exposure of the heart alone to hyperosmotic saline resulted in decreased heart rate while exposure of only the CNS resulted in an increase in heart rate. These observations suggest that the increase in heart rate that is observed in intact air‐dehydrated slugs is primarily mediated by the CNS.
Bidirectional folding of an insect epithelial monolayer
Authors: Nardi James B. , Reynolds Ingrid
Published: June 2005

Moth wing epithelium has a well‐defined apicobasal polarity expressed in the positioning of specialized junctions and microfilament bundles. This cytoarchitecture predisposes epithelial monolayers to fold with their basal surfaces outermost. However, a given epithelial population appears not to be constrained by its cytoarchitecture to fold in a particular direction. Direction of folding—either with basal surfaces or apical surfaces outermost—is determined by environmental factors and is correlated with changes in lateral cell contacts as well as dimensions of the apicalmost epithelial junctions (belt desmosomes). These configurational changes of epithelial sheets are accomplished without altering the intrinsic polarity of individual epithelial cells.
Electron microscopic observations on the process of polar body formation in artificially activated eggs of the rose bitterling
Authors: Ohta Tadayuki
Published: June 2005

Mature eggs were obtained from adult female rose bitterling, Rhodeus ocellatus ocellatus. Both intact and dechorionated eggs were activated by immersion in freshwater. The formation of the second polar body after egg activation was examined ultrastructurally by both scanning and transmission electron microscopy. The second polar body was extruded from a specialized site identified by an aggregation of thick leaf‐like projections of the egg cytoplasm, a short distance from the sperm entry site about 15 min postactivation. After extrusion, formation of a cleavage furrow was completed at the base of the polar body protuberance about 30 min postactivation. The nucleus of the extruded second polar body had a nuclear envelope. The formation of the second polar body in activated eggs are discussed.
The cylindrical or tubiliform glands of Nephila clavipes
Authors: Candelas Graciela C. , Ortiz Anselmo , Molina Carlos
Published: June 2005

The cylindrical or tubiliform glands of the spider Nephila clavipes have been studied and compared to the large ampullates on which we have previously reported. The three pairs of cylindrical or tubiliform glands secrete the fibroin for the organism's egg case. Their solubilized luminar contents migrate as a homogeneous band in Sodium dodecyl sulfate polyacrylamide gel electrophoresis and turn out to be a larger protein than that produced by the large ampullates. The excised cylindrical glands remain metabolically active for several hours in a simple culture medium, where fibroin synthesis can be monitored through the incorporation of 14C alanine. The glands' response to a fibroin production stimulus does not reach the magnitude displayed by the large ampullates, but this is to be expected since their products supply different functions in this organism. This fibroin also seems to be elongated discontinuously. Translational pauses have been detected in the secretory epithelium of cylindrical and large ampullate glands of Nephila as well as in the silk glands of Bombyx mori. Since these glands produce the fibroin for the females egg case, they should prove to be an interesting model system.
Partial characterization of the mating‐inducing factors (gamones) produced by mating type VI cells in the ciliate Euplotes patella syngen 2
Authors: Akada Rinji
Published: June 2005

The mating‐inducing factors (gamones) secreted from the mating type VI (strain 10) cells in the ciliate Euplotes patella syngen 2 have been characterized. The gamone activity was sensitive to pronase and was resistant to trypsin, chymotrypsin, heating, and periodate oxidation. DEAE‐Sepharose column chromatography of the cell‐free fluid has revealed that cells of heterozygous mating type VI (mt2/mt4) secrete two different gamones, gamones 2 and 4. These results strongly suggest that the two gamones of type VI cells are proteins that contain little or no carbohydrate moiety and are controlled by their own mating type genes.
Presence of sucrase in the yolk sac of the chick
Authors: Matsushita Susumu
Published: June 2005

The presence of sucrase in the yolk sac of the chick was studied biochemically and immunologically. The sucrase was partially purified from the yolk sac of hatched chicks and was compared with the sucrase purified from the small intestine. Immunodiffusion with antiserum against intestinal sucrase and characterization of the activity revealed that the two enzymes were almost identical. However, the size of the yolk sac sucrase was found to be slightly smaller than that of the intestinal enzyme by chromatography on Sephadex G‐200 and polyacrylamide gel electrophoresis. Immunocytochemical studies showed that the sucrase was located on the free surface of yolk sac endodermal cells, but the sucrase may also be present in the cytoplasm.
Reprograming of murine blastocoele formation
Authors: Prather Randall S. , First Neal L.
Published: June 2005

The present study shows that there is communication between reaggregated asynchronous cleavage stage blastomeres that regulates blastocoele formation. Individual blastomeres from eight‐cell murine embryos were transferred to empty zonae pellucidae, intact two‐cell embryos, or enucleated two‐cell embryos, and were examined over a period of 75 hours for development of cavitation. It was found that the isolated blastomeres cavitated concurrently with intact control eight‐cell embryos, while intact control two‐cell embryos cavitated 24 hours later. However, the embryos resulting from combining a two‐cell embryo and a blastomere from an eight‐cell embryo cavitated at a time in between the eight‐ and two‐cell controls.
Capacitated, acrosome reacted but immotile sperm, when microinjected under the mouse zona pellucida, will not fertilize the oocyte
Authors: Barg Patricia E. , Wahrman Miryam Z. , Talansky Beth E. , Gordon Jon W.
Published: June 2005

We have devised a procedure for mechanically inserting intact, acrosome reacted spermatozoa under the mouse zona pellucida, and have examined the ability of sperm so inserted to fertilize the mouse oocyte. Sperm immobilized by a variety of different methods are unable to fertilize the egg, despite the fact that electron microscopy confirms that they are acrosome reacted. Control experiments show that the oocytes are capable of being fertilized by motile sperm after the microinjection procedure, and that the immobilized sperm are able to form male pronuclei after injection directly into the ctyoplasm. These results indicate that in addition to its importance for penetration of egg investments, sperm motility is required for fusion of the gametes. Alternatively, the findings suggest that the enzymatic machinery required for sperm motility is very similar to that utilized for gamete fusion, and that destruction of one is likely to lead to inactivation of the other.
The effect of melatonin administration and short exposures to cold on body temperature of the blind subterranean mole rat (rodentia, Spalax ehrenberghi, Nehring)
Authors: Heth G. , Pevet P. , Nevo E. , Beiles A.
Published: June 2005

Improvement of the cold resistance capacity of the mole rat (Spalax ehrenbergi, Nehring), a blind subterranean rodent, was achieved following subcutaneous melatonin administration. Melatonin‐treated mole rats exhibited reduction both in initial body temperature (Tbo) and in the decrease of body temperature (ΔTb) after 6 hours of exposure to cold. The tested mole rats were acclimated to and kept during the experiment, under long (16L/8D) photoperiod schedule while the effects of melatonin administration on body temperature simulated the effects of short photoperiod conditions. These results suggest that in mole rats, melatonin biochemically mediates photoperiodic information into body temperature physiological response. As a byproduct of the original experiment, it was found that frequently repeated short (6 hours) exposure to cold (Ta = 5 ± 1°C) can in itself initiate an improvement of cold resistance capacity similar to the effect of melatonin administration. This supports the idea that mole rats may improve their cold resistance in response to either photoperiodic or climatic changes.
Development of fast singing muscles in a katydid
Authors: Ready Neal E.
Published: June 2005

In males of the katydid Neoconocephalus robustus, mesothoracic wings are used in flight (wing stroke frequence = 20 Hz) and stridulation (200 Hz), while the metathoracic wings are used in flight alone. Most mesothoracic wing muscles produce much briefer isometric twitches than metathoracic counterparts. The mesothoracic first tergocoxal muscle (TCX1) has a twitch duration (onset to 50% relaxation, 35°C) of 6–8 ms and the metathoracic TXC1 a twitch duration of 12–15 ms. The TCX1 muscles from animals one and two instars from adulthood produce twitches similar in duration to those of the adult metathoracic TCX1. The twitch duration of the mesothoracic TCX1 acquires its adult brevity gradually over the first 5 days of adult life. Both TCX1 muscles increase greatly in size and mitochondrial content around the time of the terminal molt. During this period the mesothoracic TCX1 develops narrower myofibrils and a smaller ratio of fibril volume to sarcoplasmic reticulum volume than is characteristic of the metathoracic TCX1. Changes in the ultrastructure of the mesothoracic TCX1 precede changes in contraction kinetics around the time of the terminal molt so that there is not a strict correlation between muscle structure and performance during the period of rapid growth.
Stimulation of genital eversion in the land snail Helix aspersa by extracts of the glands of the dart apparatus
Authors: Chung Daniel J. D.
Published: June 2005

The dart apparatus, used during courtship in some groups of hermaphroditic land snails, has long been assumed to have a “stimulatory” effect on the mating partner, though how stimulation occurs and exactly what function it serves has never been determined. In this study, extracts of the mucous glands of the dart apparatus of the land snail Helix aspersa were injected into conspecifics and into a related snail, Cepaea nemoralis, in order to test the hypothesis that the dart is used to achieve inflow of bioactive mucous gland secretions into the darted snail. Helix aspersa injected with the extract responded by everting their terminal genitals; eversion normally takes place during courtship and mating. Boiling the extract increased the bioactivity. Pronase‐treated extract lost bioactivity, and gel filtration of the boiled extract indicated that the active substance has a molecular weight of about 5,000. The active substance may be a polypeptide. Cepaea nemoralis also everted their genitals when injected with the boiled Helix extract. The active substance appears to be a contact sex pheromone, the second such pheromone in a pulmonate land snail for which experimental evidence has been obtained.