bluuebunny/crossref_metadata_2025 huggingface dataset:
DNA synthesis in the mouse blastocyst during the beginning of delayed implantation
Authors: Given Randall L.
Published: June 2005

The spatiotemporal pattern of DNA synthesis in the mouse embryo at the beginning of metabolic dormancy was examined. Embryos were recovered from females at intervals following ovariectomy at 1100 hours on day 4 of pregnancy, incubated in vitro for 1 h in the presence of [3H]thymidine, and prepared for light microscopic autoradiography. The proportion of labeled cells in the embryo remained high (40–60%) for 18 h after ovariectomy and then declined gradually to 12% by 96 h. However, analysis of individual cell subpopulations showed that the decline was not uniform in all regions of the blastocyst. Labeling was high over the inner cell mass (ICM) during all time intervals in the study, while labeling over the mural trophoblast cells declined sharply by 24 h after ovariectomy. Labeling over the polar trophoblast also declined but had values that were intermediate between the ICM and mural trophoblast regions of the blastocyst. These regional differences in DNA synthesis during the arrest of development suggest that intermediate steps are involved in control of DNA synthesis in the embryo and that the ICM may play a role in the different responses of the trophoblast cell populations.
Ultrastructural localization of RFamide‐like peptides in neuronal dense‐cored vesicles in the peduncle of Hydra
Authors: Koizumi Osamu , Wilson Jeff D. , Grimmelikhuijzen Cornelis J. P. , Westfall Jane A.
Published: June 2005

The presence of Arg‐Phe‐amide (RFamide)‐like peptides in dense‐cored vesicles in neurons of the peduncle of Hydra was demonstrated by immunogold electron microscopy. Thin sections of Lowicryl‐embedded tissue labeled with antisera to RFamide and 5‐nm gold‐conjugated, secondary antibody and of Epon‐Araldite‐embedded tissue labeled with 15‐nm gold particles revealed a concentration of RFamide‐like immunoreactivity over the granular cores of vesicles in epidermal ganglion cells. Gold‐labeled, dense‐cored vesicles were present in the perikaryon, long thin neurites, and axon terminals of these neurons. The aggregation of labeled dense‐cored vesicles in an axon terminal on the myoneme of an epitheliomuscular cell suggests a possible function of RFamide‐like peptides in neuromuscular transmission. Gold staining of dense‐cored vesicles completely disappeared when the RFamide antiserum was preabsorbed with 10 μg/ml RFamide. These results are the first demonstration that the dense‐cored vesicles of Hydra neurons contain a neuropeptide.
Ability of various injuries to promote resorption of denervated, nerve independent regenerates of adult newts
Authors: Winner Cherie Olsen
Published: June 2005

Young blastemas of the newt resorb if the limb is denervated, and are thus called “nerve dependent.” Late bud and later stage regenerates are termed “nerve independent” because, while denervation inhibits their growth, they proceed through differentiation to form a normally patterned regenerate. Schotté and Liversage ('59) found that reamputation of a denervated nerve independent regenerate causes it to resorb. The present study asked whether injuries of varying severity are equally effective at promoting resorption. Newt forelimbs were amputated through the mid‐radius/ulna. At nerve independent stages, the regenerates were denervated and injured in one of a variety of ways, then monitored for signs of resorption. Reamputation of the tip or incisions which created large gaps in the wound epidermis promoted resorption in 77–90% of the cases. Histology showed that the tissue removed by tip reamputation was a small proportion of the entire regenerate, suggesting that blastema resorption is not determined simply by the number of cells directly affected by the injury. Pin prick injuries, which created small disruptions of the wound epidermis, never caused resorption. Devascularization, caused by severing the brachial artery, promoted resorption in 17% of cases. These results are not consistent with the hypothesis that avascularity is a major causative factor in nerve dependence.
Role of the mouse visceral yolk sac in nutrition: Inhibition by a somatomedin inhibitor
Authors: Balkan Wayne , Phillips L. S. , Goldstein Steven , Sadler T. W.
Published: June 2005

A low molecular weight somatomedin inhibitory serum fraction (SI), obtained from streptozotocin‐induced diabetic rats, causes morphological abnormalities and growth reduction in mouse embryos grown in whole embryo culture (WEC). These abnormalities are thought to be caused, at least in part, by a failure of the visceral yolk sac (VYS) to properly degrade proteins, a process that normally provides the conceptus with amino acids and peptides for de novo protein sythesis (histiotrophic untrition). To test this hypothesis, embryos exposed to the SI were provided with a mixture of ten essential amino acids (supplemented group) in an attempt to circumvent SI‐induced VYS dysfunction. Results showed that 82.4% (14/17) of embryos in the amino acid‐supplemented group exhibited improved growth and development compared to those embryos exposed to medium containing the SI alone (unsupplemented group). Supplemented embryos showed greater expansion of the brain regions, improved visceral arch development, and increased protein content compared to nonsupplemented SI‐treated embryos. However, these parameters were still reduced compared to controls. VYSs from both the unsupplemented and amino acid‐supplemented groups were identical with respect to alterations in morphology and increased protein content compared to VYSs from conceptuses cultured in control medium (with or without amino acid supplementation). The improvement in embryonic growth and development due to amino acid supplementation in spite of VYS abnormalities supports the hypothesis that nutritional deprivation is one aspect of SI‐induced teratogenesis.
Mammalian limb bud development: In situ fate maps of early hindlimb buds
Authors: Muneoka Ken , Wanek Nancy , Bryant Susan V.
Published: June 2005

Fate maps of the developing mouse hindlimb bud have been constructed for the first time using exo utero surgical techniques and carbon particle injections. Such fate maps demonstrate that the limb develops in a proximal to distal manner as a result of distal expansion. The anterior‐posterior extent of the limb bud develops asymmetrically with the posterior half giving rise to slightly more of the digit pattern (digits 3–5) than the anterior half (digits 1 and 2). We found no evidence for the occurrence of extensive cellular rearrangements during limb development, and the free limb bud appears to give rise to only zeugo‐and autopodial elements with the stylopod arising in the body wall proximal to the bud. These results are consistent with our current understanding of limb development in lower vertebrates and also provide detailed information that will be useful for future limb studies in mammals.
The involvement of thyroxine and daylength in the development of photorefractoriness in European starlings
Authors: Dawson A.
Published: June 2005

Thyroidectomized starlings on long days do not become photorefractory. Four experiments were done to investigate the roles of thyroxine and daylength in the development of photorefractoriness. 1) Pharmacological doses of thyroxine administered to thyroidectomized starlings on long days induced photorefractoriness and molt, whereas the same treatment to birds on short days was ineffective. 2) Maintenance of intact starlings on a daylength long enough to cause full gonadal maturation but not quite long enough to induce photorefractoriness caused no progression toward photorefractoriness; subsequent gonadal regression after transfer to long day days occurred at the same rate as in intact birds transferred directly from short days to long days. 3) In thyroidectomized birds held on long days and then treated with thyroxine, gonadal regression occurred at the same time as in thyroidectomized birds held on short days and then treated with thyroxine while simultaneously being transferred to long days. 4) Thyroidectomized birds held on long days and treated with different doses of thyroxine became photorefractory at the same rate. These results demonstrate that thyroxine does not drive the process leading to photorefractoriness. For photorefractoriness to occur there has to be a temporal coincidence of daylength in excess of a critical daylength and the presence of thyroxine; thyroxine specifically permits the process to respond appropriately to ambient daylength.
Hydrogen sulfide oxidation by abundant nonhemoglobin heme compounds in marine invertebrates from sulfide‐rich habitats
Authors: Powell Mark A. , Arp Alissa J.
Published: June 2005

Several animals from hydrogen sulfide‐rich marine habitats were found to contain unusual heme compounds (hematins) at levels of up to 10 mM; these hematins catalyzed the oxidation of sulfide and may protect the animals from sulfide poisoning. Freshly captured specimens of the echiuran worm Urechis caupo contained 0–10 mM hematin in their coelomic fluid. This hematin was present within coelomocytes in addition to 0.5–2 mM hemoglobin present in these cells as a functional oxygen‐binding hemoprotein. The hematin was present in granules, and was not associated with a globin, cytochrome, or other protein known to have a heme prosthetic group. The hematin catalyzed oxidation of hydrogen sulfide. Further studies revealed that similar hematins were present in gill tissues of bivalve molluscs, which harbor vast numbers of endosymbiotic sulfur bacteria. Hematin was found at 1.0 mM, in addition to 0.1 mM hemoglobin, in the gill tissue of the clam Solemya reidi. Hematin was also found at 1–2 mM in gill tissue of two other clams, Calyptogena magnifica and Lucinoma annulata, in addition to < 0.4 mM hemoglobin. These clam hematins also appeared to be catalysts of sulfide oxidation.
Metabolic changes in coho and chinook salmon resulting from acute insufficiency in pancreatic hormones
Authors: Plisetskaya Erika M. , Sheridan Mark A. , Mommsen Thomas P.
Published: June 2005

Acute deficiency in pancreatic peptides (insulin, somatostatin‐25, glucagon, and glucagon‐like peptide) was invoked for 9–12 hr in coho, Oncorhynchus kisutch, and chinook, O. tshawytscha, salmon by administration of specific antisera raised against purified salmon hormones.

Insulin‐deficient fish were hyperglycemic, had diminished glycogen content in the liver (Plisetskaya et al., '88a, elevated liver triacylglycerol lipase activity, and higher concentration of plasma triiodothyronine (T3) compared to a control group of fish injected with nonspecific rabbit serum. After immunoneutralization of somatostatin‐25, fish remained normoglycemic, with higher liver glycogen content, decreased lipase activity, and elevated plasma levels of insulin, while the levels of T3 declined. The induced deficiency in glucagon family peptides led to comparatively smaller changes: liver glycogen content was increased after anti‐glucagon‐like peptide (aGLP) injection and transient hyperglycemia was apparent following anti‐glucagon (aGLU) administration. Circulating levels of insulin remained unaffected for at least 9 hr following aGLU and aGLP treatments. The velocity of pyruvate kinase at 2.5 mM phosphoenolpyruvate (V2.5) was depressed, especially after the combined administration of aGLU + aGLP.

The effectiveness of immunoneutralization experiments was greatly dependent on the particular stage of the fish life cycle. Antisera against fish pancreatic peptides proved to be a suitable tool in the studies of hormonal regulation of fish metabolism.
Farnesoic acid as a major product of release from crustacean mandibular organs in vitro
Authors: Tobe S. S. , Young D. A. , Khoo H. W. , Baker F. C.
Published: June 2005

Incubation of mandibular organs (MO) from the crab Scylla serrata with medium containing [2‐14C]‐acetate and [methyl‐3H]‐methionine results in the biosynthesis and release of, predominantly, farnesoic acid and of methyl farnesoate. The identity of each was confirmed by liquid chromatography and gas chromatography/mass spectrometry (GS/MS). Farnesoic acid is released into the incubation medium at a rate tenfold greater than methyl farnesoate. Release of the acid was linear over an 8‐hr incubation period. However, the amount of farnesoic acid within the MO did not equal the quantity of methyl farnesoate in the glands. Analysis of haemolymph extracts by GC/MS confirmed the presence of methyl farnesoate but farnesoic acid was not detected. These data suggest that farnesoic acid is released by the MO of S. serrata and either rapidly metabolized or sequestered by the tissues. It is possible that farnesoic acid may be a prohormone and converted into other isoprenoid products.
Some effects of salmon calcitonin on calcium metabolism in the crustacean Orchestia during the molt cycle
Authors: Sellem Evelyne , Graf Fraņclois , Meyran Jean‐claude
Published: June 2005

In the terrestrial amphipod Orchestia cavimana, investigations of the variations of the total hemolymphatic calcium during the normal molt cycle revealed that a calcium balance is maintained in intermolt, as observed in numerous crustaceans. During premolt, hypercalcemia occurs, related to the marked calcium reabsorption from the old cuticle, which may promote the storage of a part of this calcium within the midgut posterior caeca. The calcium levels fall after exuviation to late postmolt to the low basal levels of intermolt; this may reflect the imbalance between the rates of calcification of the newly secreted cuticle and uptake of calcium within the posterior caeca.

Administration of salmon calcitonin lowers calcium levels in intermolt and early premolt, when endogenous calcitonin‐like activity and ecdysteroid titers are low, but has no effect in late premolt when endogenous calcitonin‐like activity is important.
Time‐ and temperature‐dependent appearance of vitellogenin in Golgi vesicles and serum after estrogen treatment of salmon (Salmo salar)
Authors: Olin T. , Westman A. , von der Decken A.
Published: June 2005

The temperature‐dependent time course of vitellogenesis was examined in presmolt salmon (Salmo salar). Fishes were kept at 8°C or 16°C and injected with 17‐β‐estradiol. The rise in translation activity in liver preceeded that of RNA. At both acclimation temperatures, vitellogenin appeared in the Golgi vesicles at 3 days after the initial hormone injection. At 8°C, vitellogenin was detectable in the serum on day 7 and at 16°C on day 3 after the initial hormone treatment. At 8°C, protein synthesis per g wet weight of liver as well as vitellogenin content in the Golgi vesicles and in serum continued to rise during the 2 weeks of treatment. At 16°C, protein synthesis per g wet weight of liver reached a plateau during the second week of hormone treatment. A similar trend was seen in the vitellogenin content in the Golgi vesicles and the serum, suggesting a limiting step in either the translation or the export process of the protein at elevated temperature. The results indicate a correlation between translation activity, accumulation of vitellogenin in the Golgi vesicles, and concentration of vitellogenin in the blood.
β‐Adrenergic blockers prevent short photoperiod‐induced gonadal regression, but not melatonin‐induced regression in male syrian hamsters
Authors: Champney Thomas H.
Published: June 2005

Pineal melatonin synthesis is regulated by norepinephrine at β‐adrenergic receptors on pinealocytes. Melatonin released from the pineal is believed to be responsible for short photoperiod‐induced gonadal regression. By blocking melatonin production at the β‐adrenergic receptor with β‐adrenergic antagonists, short photoperiod‐induced gonadal regression was prevented. Propranolol or nadolol injected daily in the late afternoon prohibited short photoperiod‐produced testicular regression in male Syrian hamsters. Likewise, propranolol and nadolol pellets were able to block short photoperiod‐induced gonadal regression. Interestingly, in the presence of β‐adrenergic antagonists, gonadal regression was still produced by daily afternoon injections of melatonin. These results indicate that propranolol or nadolol can be used to “pharmacologically pinealectomize” hamsters and block the physiological action of the pineal.
Development of porcine embryos from the one‐cell stage to blastocyst in mouse oviducts maintained in organ culture
Authors: Krisher Rebecca L. , Petters Robert M. , Johnson Bryan H. , Bavister Barry D. , Archibong Anthony E.
Published: June 2005

Successful development of porcine embryos from the one‐cell stage to the blastocyst stage has been accomplished using mouse oviducts in organ culture. One‐cell embryos were transferred to mouse oviducts maintained in organ culture and were cultured for 6 days. Control embryos from each donor pig were cultured in a modified Krebs‐Ringer bicarbonate medium. Thus control and experimental embryos obtained from the same individual pig could be directly compared. At the end of the culture period, all embryos were scored for the stage of development attained and stained to allow the cell number of each embryo to be counted. In medium alone, only 35.7% of the one‐cell embryos reached the morula or blastocyst stage, whereas 78.1% of the one‐cell embryos transferred to mouse oviducts reached the morula or blastocyst stage. Of those embryos reaching the morula or blastocyst stage, cell numbers were similar for the two treatments (medium alone vs. oviduct culture). The procedure described for mouse oviduct organ culture provides a simple method for culturing early‐stage pig embryos to the morula or blastocyst stage prior to embryo transfer.
Fate mapping the avian neural plate with quail/chick chimeras: Origin of prospective median wedge cells
Authors: Schoenwolf Gary C. , Bortier Hilde , Vakaet Lucien
Published: June 2005

The origin of prospective M cells, which are median neuroepithelial cells that become wedge‐shaped during bending of the neural plate and eventually form the midline floor of the neural tube, was determined by constructing quail/chick chimeras and using the quail nucleolar marker to identify quail donor cells in chick host blastoderms. Two possible sites of prospective M‐cell origin in the epiblast were examined: a single, midline rudiment located just rostral to Hensen's node and paired rudiments flanking the cranial part of the primitive streak. Our results suggest that M cells arise exclusively from the midline, prenodal rudiment. From this rudiment, M cells extend caudally throughout the entire length of the neuroepithelium. This new information on the origin of prospective M cells will aid in the analysis of their role in neurulation.
Induction of the acrosome reaction in ejaculated goat spermatozoa by preincubation in chemically defined medium
Authors: Kusunoki Hiroshi , Sakaue Morito , Kato Seishiro , Kanda Sunao
Published: June 2005

The aim of the present study was to examine the effects of the elimination of energy substrate from the medium and the effects of the preincubation vessel, temperature, and time on the induction of the acrosome reaction in ejaculated goat spermatozoa in chemically defined medium. Washed spermatozoa were resuspended in Brackett–Oliphant (BO) medium or substrate‐free BO medium to give a high concentration and preincubated in open test tubes or sealed glass tubes at 37.0 or 39.5°C for 1, 2, or 3 h. Sperm acrosome reaction was evaluated using a simplified triple‐stain technique and a hamster test. It was found that the goat sperm acrosome reaction occurred more readily in the sealed glass tubes than in open test tubes, in substrate‐free BO medium than in BO medium, and at 39.5 than at 37.0°C. During preincubation with substrate‐free BO medium in sealed glass tubes at 39.5°C, the optimum time necessary to induce the acrosome reaction in goat spermatozoa was 2–3 h.
Catecholamine release by catecholamines in the eel does not require the presence of brain or anterior spinal cord
Authors: Hathaway Charles B. , Brinn Jack E. , Epple August
Published: June 2005

The catecholamine‐producing chromaffin cells of the American eel are strongly innervated by fibers, which, by ultrastructural criteria, seem to be cholinergic. However, neither removal of the brain nor removal of the brain combined with extirpation of the anterior spinal cord prevents the release of catecholamines into the circulation by catecholamines. It appears that the chromaffin cells are controlled by both nervous and humoral stimuli, and that at least some of the latter do not require the presence of “preganglionic” innervation.
Evidence that somatic and sympathetic nervous system neurotransmitters, not circulating epinephrine, mediate the immediate responses to a sudden threat in the American alligator (Alligator mississippiensis)
Authors: deRoos Roger , Rumpf Ronald P. , Berry Michael W.
Published: June 2005

The qualitative and quantitative temporal effects of a 2‐min handling stress, both with and without pretreatment with tubocurarine, and the intraaortic infusion of epinephrine, both with and without pretreatment with a combination of phentolamine and propranolol, on plasma lactate, glucose, and hematocrit levels were compared in the American alligator (Alligator mississippiensis). The drugs and epinephrine were administered, and serial blood samples were collected, via a nonocclusive cannula chronically placed in the left aortic arch. Plasma lactate and glucose were measured by standard enzymatic procedures. Plasma lactate rose approximately 92% by the end of the 2‐min handling period and to maxima of 1,091 ± 476% greater than the time‐zero levels by 15 min. The hematocrit also increased rapidly to maxima of 11 ± 3.1% greater than the time‐zero levels by 5 min. Plasma glucose levels did not change significantly. The handling‐induced lactate and hematocrit increases were prevented by pretreatment with tubocurarine that blocks acetylcholine receptors at the skeletal muscle neuroeffector junction. Epinephrine infusion resulted in delayed, comparatively slow increases in plasma lactate, glucose, and the hematocrit. The peak levels for lactate were 334 ± 92% by 6 hr, for glucose were 135 ± 8% by 90 min, and for hematocrit were 10.9 ± 5.6% by 90 min. Pretreatment with the combination of phentolamine and propranolol that blocks mammalian “alpha” and “beta” adrenergic receptors, respectively, prevented the epinephrine‐induced increases in glucose and hematocrit levels, but not the plasma lactate increases. The results support the conclusion that the immediate responses of the alligator to a sudden threat are mediated by the synergistic effects of the somatic nervous system neurotransmitter acetylcholine, released at the skeletal muscle neuroeffector junction, and the sympathetic nervous system neurotransmitter (presumably norepinephrine), released at the neuroeffector junctions of the relevant visceral tissues and organs. In contrast, the participation of adrenal chromaffin tissue epinephrine secretion in the immediate responses is precluded by the long circulation and response times.
Temporal separation of rhabdom shrinkage and mvb formation in the light‐adapting crayfish retina
Authors: Piekos W. Barry
Published: June 2005

By using experimental light regimes, it is possible to alter independently the timing of both multivesicular body (MVB) production and decreases in rhabdom diameter. As a result, two distinct phases of MVB synthesis are revealed, neither of which appears temporally linked to rhabdom shrinkage. This supports the idea that MVB production and diminishing rhabdoms are not causally related in the manner predicted by the lysosome‐related‐body (LRB) hypothesis of rhabdom cycling. Furthermore, a statistically significant relationship is found between midday rhabdom enlargement and a decrease in the fractional volume of MVBs.
Notochordal induction of cell wedging in the chick neural plate and its role in neural tube formation
Authors: Smith Jodi L. , Schoenwolf Gary C.
Published: June 2005

Cells in the median hinge point (MHP) of the bending chick neural plate are tightly apposed to the underlying notochord. These cells differ from those in adjacent lateral neuroepithelial areas (L) in that MHP cells are short and mainly wedge‐shaped and line a furrow, whereas L cells are tall and mainly spindle‐shaped and do not line a furrow. Cell generation time also differs in these regions. These consistent differences are detectable only after the notochord has formed and established contact with the neural plate; it is unclear whether they result from self‐differentiation or induction. Two experiments were performed to evaluate the hypothesis that MHP characteristics develop owing to inductive interactions between the notochord and overlying neuroepithelial cells. First, notochordless chick embryos were generated to determine whether midline neuroepithelial cells still developed typical MHP characteristics. In the absence of the notochord, such characteristics did not develop. Second, isolated segments of quail notochord were transplanted subjacent to L of chick hosts to ascertain whether the notochord is capable of inducing MHP characteristics in L cells. When transplanted notochordal segments established apposition with host L cells, the apposing L cells usually developed typical MHP characteristics. Collectively, these results provide strong evidence that the notochord plays an inductive role in the formation of MHP characteristics. This investigation further revealed that bending can occur in the absence of MHP characteristics, forming a neural tube with an abnormal morphology. Thus, the formation of such characteristics, particularly cell wedging, is not required for bending but plays a major role in generating the normal cross‐sectional morphology of the neural tube.
Steady‐state and dynamic properties of photomechanical light and dark adaptation in the eye of the shrimp Eualus gaimardii (crustacea, natantia)
Authors: Nordtug Trond , Krekling Sturla
Published: June 2005

A reflectometric method was used to study dark and light dark adaptation in shrimps (Eualus) by recording the reflectometric response to alternating periods of light‐off and light‐on that varied in intensity. We found that 1) During light‐off and light‐on periods the response slowly attained an upper and lower asymptotic level, respectively, followed by a steady‐state phase of these levels. The steady‐state level correlated strongly with the position of the distal screening pigment. 2) Steady‐state response plotted against log intensity defined an intensity‐response function representing the dynamic range of the distal pigment and consequently that of the effective aperture. The threshold where the pigment departed from its fully light‐ and dark‐adapted position was 10−5.5 and 10−9.5 W/cm2, respectively. Over this interval the intensity‐response function was linear and the increase in effective aperture equalled about .5 log unit gain in image brightness per log unit change in intensity. 3) The intensity‐response function showed cyclic shifts along the intensity continuum caused by endogeneous factors. 4) The duration of light adaptation was constant while rate of change increased linearly as a function of log intensity. Dark adaptation had similar properties at low intensities, thereafter its rate of change was constant while the duration increased linearly. These findings are consistent with the idea that the distal pigment is controlled by two hormones, the dark‐adapting hormone being subordinated to the light‐adapting one. Both the size of the dynamic intensity range and the temporal properties of light and dark adaptation showed that the photomechanical mechanism is well adapted to cope with twilight viewing conditions.
Changes in ornithine decarboxylase activity and polyamine content and effects of polyamine inhibitors in the regenerating planarian Dugesia (G) tigrina
Authors: Saló Emili , Baguñà Jaume
Published: June 2005

Ornithine decarboxylase (ODC), the diamine putrescine, and the polyamines spermidine and spermine have been shown to be present in the intact and regenerating planarian Dugesia (G) tigrina. As early as 1 hour after cutting, ODC activity increases, with maxima at 8 hours and 2 days of regeneration, mainly in regions near the wound. Putrescine varied like ODC, with maxima at 8 hours and 3 days, when cell proliferation is highest, whereas spermidine and spermine had lesser and later increases, merely in regions near the wound, with peaks at 5 days of regeneration when cell differentiation is greatest. The inhibitors of polyamine synthesis difluoromethylornithine (DFMO) and methylglyoxal bis(guanylhydrazone) (MGBG) decreased the levels of putrescine, spermidine, and spermine and lowered the rates of cell proliferation and differentiation. DFMO especially decreased the level of putrescine and the rate of cell proliferation, whereas MGBG reduced mainly the levels of spermidine and spermine and the rate of cell differentiation. On the basis of these observations, we suggest that, in planarian regeneration, ODC and putrescine are mainly involved in the control of cell proliferation, whereas spermidine and spermine are more related to cell differentiative processes.
Bacterial action of fertilization envelope extract from eggs of the fish Cyprinus carpio and Plecoglossus altivelis
Authors: Kudo Shigeharu , Inoue Matsuhisa
Published: June 2005

The vitelline envelope (VE) and fertilization envelope (FE) in eggs of the fish Cyprinus carpio and Plecoglossus altivelis were purified by homogenization of eggs or embryos in 5 mM Tris—HCl buffer, pH 7.0, containing 2 mM ethylenediamine tetraacetic acid disodium salt (EDTA), except for processing of VEs in Plecoglossus eggs, and by repeated washing with the same buffer. To extract the outermost layer material, the purified VEs and FEs were processed overnight at 4°C in 5 mM Tris‐HCl buffer, pH 7.0, containing 8 mM 2‐mercaptoethanol, 2 mM EDTA, 0.3 M α‐lactose, 0.3 M glucose, and 0.9% NaCl. Since extraction of the outermost layer of the VEs of Cyprinus eggs in this solution was found to be ultrastructurally incomplete, further sonication in the same buffer was necessary. The solution extracted from purified VEs or FEs was dialyzed against 5 mM Tris‐HCl buffer, pH 7.0, followed by lyophilization. The extracts from the FEs from both fish species contained two kinds of lectins, one agglutinated human B‐type erythrocytes and the other nonspecifically agglutinated fish spermatozoa, and both extracts had a strong bactericidal effect on Vibrio anguillarum that was isolated from diseased cultured fish, but not on Aeromonas hydrophila and Escherichia coli. The extracts of purified VEs from eggs of both fish had no bactericidal effect on the bacteria examined, nor any agglutination effect on human erythrocytes and fish spermatozoa.
Effect of sensory input from the tongue on jaw movement in normal feeding in the opossum
Authors: Thexton A. J. , Crompton A. W.
Published: June 2005

Opossums were presented with solid and liquid foods. The movements of the jaw and tongue were recorded cineradiographically together with recordings of the EMG activity in muscles opening the jaw and moving the base of the tongue (hyoid). The jaw opening in each cycle was in two stages–01 and 02; 01 had a constant amplitude irrespective of the food ingested. Ingestion of liquid (which involved continuous accumulation of a liquid bolus in the valleculae prior to swallowing) was associated with cycles of oral movement in which 02 was small; tongue retraction was associated with this opening. In contrast, solid and semisolid food ingestion was associated with large angles of jaw opening in 02 that also coincided with the tongue retraction. In this latter case a characteristic pattern of EMG activity, in which all the muscles moving the hyoid were simultaneously active, was added to the pattern seen in lapping; this additional activity had an EMG pattern that was consistent with a jaw opening reflex. The findings contrast with other reports that the jaw opening reflex is suppressed in mastication. Experimentally induced tongue contact with a variety of solid surfaces during lapping (an activity involving accumulation of a liquid bolus in the valleculae) induced neither increased jaw opening nor the additional EMG pattern. However, in situations when there was no bolus in the valleculae, additional jaw opening activity was elicited when the tongue contracted solids intra‐ or extra‐orally. It is suggested that the ability of sensory input, from the anterior tongue, to elicit a jaw opening reflex and to change the type of jaw/tongue cycle was dependent upon the extent of bolus accumulation in the valleculae and therefore indirectly upon the consistency of the food.
High‐molecular‐weight serine proteinase from lobster muscle that degrades myofibrillar proteins
Authors: Mykles Donald L.
Published: June 2005

A latent alkaline serine proteinase (ASP) has been extracted from the soluble fraction of lobster claw and abdominal muscles. The enzyme, which was irreversibly activated 30‐ to 40‐fold by brief (2–3 min) heating at 60°C, had an optimal caseinolytic activity at pH 7.75. Its molecular weight was estimated to be 740,000 by gel filtration chromatography. Serine protease inhibitors (diisopropylfluorophosphate, phenylmethanesulfonyl fluoride, soybean trypsin inhibitor, aprotinin, benzamidine, and chloromethyl ketones) suppressed ASP activity 22 to 70%. In addition, sulfhydryl‐blocking reagents and hemin inhibited activity 69 to 100%; leupeptin and E‐64, however, did not. Pepstatin A, ethylenediaminetetraacetate, and adenosine triphosphate were without effect. These results suggest that the lobster ASP is a serine proteinase that contains one or more sulfhydryl groups essential for catalysis. ASP was stimulated by dithiothreitol and inhibited by CaCl2 and oleic and linoleic acids. The enzyme was partially activated by low concentrations of sodium dodecyl sulfate; 0.05% produced activities 13% of that of preparations heated at 60°C. Neither poly‐L‐lysine, urea, dimethylsulfoxide, oleic acid, linoleic acid, nor N‐ethylmaleimide activated the enzyme. The ASP degraded most myofibrillar proteins, but showed a preferential hydrolysis of paramyosin, troponin‐I and ‐C, and myosin α light chain.
Rapid postembryonic development of a cricket flight muscle
Authors: Novicki Andrea
Published: June 2005

The metathoracic dorsal longitudinal muscle (DLM) of the cricket Teleogryllus oceanicus differentiated and developed rapidly over the last nymphal instar. Within eight days, the muscle mass increased by a factor of 15 and the relative volume of mitochondria quadrupled, while the relative amounts of myofibril and sarcoplasmic reticulum decreased. Tracheoblasts began to invade the muscle fibers immediately before the adult molt. Muscle mass continued to increase until four days after the adult molt, but the relative volumes of the ultrastructural components did not change. Within two weeks following the adult molt, the muscles in some of the animals began to degenerate.
Control of growth and ultrastructural maturation of a cricket flight muscle
Authors: Novicki Andrea
Published: June 2005

The metathoracic dorsal longitudinal muscle (DLM) in the cricket Teleogryllus oceanicus increased in mass and rapidly acquired interfibrillar tracheoles and an increased proportion of mitochondria around the time of the adult molt. Both neural input and juvenile hormone levels were investigated as possible factors controlling this rapid maturation. Motor axons to the muscle were cut early in the last nymphal instar, and muscle growth slowed but ultrastructural maturation continued; the percentage of muscle volume occupied by mitochondria tripled and tracheoblasts invaded the fibers in both the denervated and contralateral innervated muscles. Newly molted last instar nymphs were treated with methoprene, a juvenile hormone analog, and examined four days following the next molt. Muscle growth was slowed but not stopped. Both mitochondrial proliferation and tracheoblast formation were completely blocked by hormone treatment. This study shows that both neural input and low levels of juvenile hormone are required for muscle growth. However, ultrastructural maturation seems to depend exclusively on low levels of juvenile hormone.
Regeneration of the dermoepidermal junction in anuran larval skin
Authors: Kinoshita Tsutomu , Takahama Hideki , Sasaki Fumie , Watanabe Kyozo
Published: June 2005

In anuran larval skin, several ultrastructures are formed at the dermoepidermal interface, and these include half‐desmosomes, basal lamina, and anchoring fibrils. Regional differences in the tadpole skin were assessed in terms of the process of regeneration of the junctional structures. The dermoepidermal interface was specifically destroyed by treatment with a neutral protease at pre‐ (stage V), pro‐ (stage XVIII), and climactic metamorphosis (stage XXI). The regeneration of the junctional structures was then compared between the skin of the tail and the back. Regardless of the metamorphic stages, the back skin regenerated complete structures, which contained the same number of half‐desmosomes as in the control, within 3 days after treatment. In the tail skin from tadpoles at premetamorphosis, basal lamina and half‐desmosomes were regenerated 2 days later than was the back skin. The ability of the tail skin to regenerate decreased as metamorphosis proceeded. When the enzymatic treatment was performed on skin removed at the climax of metamorphosis, the tail skin underwent histolysis without completion of junctional repair. In experiments with heterotypically recombined skins, active regeneration similar to that of the back skin was observed in recombinants of tail epidermis and back dermis. However, the recombinants of back dermis with tail dermis produced only basal lamina and amorphous material beneath the epidermis. These results suggest that a regional difference, with respect to the regenerating ability of the dermoepidermal junction, already exists in the skin of the premetamorphic tadpole and that this difference depends on the dermal components of the skin.
Cross‐fertilization between Syrian and Chinese hamsters
Authors: Roldan E. R. S. , Yanagimachi R.
Published: June 2005

The role of the zona pellucida in the specificity of fertilization was studied by cross‐inseminations between Syrian (Golden) and Chinese hamster gametes. Cumulus‐enclosed eggs from both Syrian and Chinese hamsters were placed together in one dish and inseminated with spermatozoa from either one or the other species. Fertilization always took place between gametes of homologous species. Chinese hamster spermatozoa failed to bind to the zona pellucida of Syrian hamster eggs; hence, fertilization was never observed. However, Chinese hamster spermatozoa could fertilize zona‐free Syrian hamster eggs. In the reciprocal cross, a large number of Syrian hamster spermatozoa could bind to and penetrate the zonae of Chinese hamster eggs. However, fusion of Syrian hamster spermatozoa with the vitellus of zona‐intact Chinese hamster eggs was never observed. After removal of the zona pellucida, only a small percentage (31%) of Syrian hamster spermatozoa could fuse with Chinese hamster vitelli. Thus, in these species, the mechanisms of interspecific gamete recognition and the prevention of interspecies fertilization seem to differ according to the direction of the cross. In Syrian hamster eggs, the block to interspecies fertilization seems to exist at the level of the zona pellucida, while in Chinese hamster eggs the block is at the level of the egg plasma membrane. The implications of these results in analyses of the genetics of spermatozoa, the molecular basis of sperm‐egg recognition, and mechanisms of reproductive isolation leading to speciation, are discussed.
Cultivation and differentiation of satellite cells from skeletal muscle of the rainbow trout Salmo gairdneri
Authors: Powell R. L. , Dodson M. V. , Cloud J. G.
Published: June 2005

Postembryonic myogenic satellite cells have previously been identified by microscopic methods in skeletal muscle of the rainbow trout, Salmo gairdneri, and are considered to be responsible for myofiber hyperplasia and hypertrophy during the growth of skeletal muscle. However, methods to harvest satellite cells from fish skeletal muscle tissue and data to demonstrate that fish satellite cells can grow in primary cell culture appear to be lacking. Therefore, the objectives of the present preliminary research were 1) to determine if satellite cells from postembryonic rainbow trout skeletal muscle can be harvested and 2) to determine if these satellite cells can differentiate to produce multinucleated, striated myotubes in vitro. Mononucleated cells were isolated by enzymatic digestion of minced skeletal muscle tissue followed by differential centrifugation. The cells were then cultured at 20°C in Leibovitz's L‐15 medium supplemented with 15% fetal bovine serum and antibiotics. Fusion of satellite cells to form multinucleated tubular structures similar to mammalian satellite cell‐derived myotubes occurred from 3 to 6 days after initial plating; myofibrillar striations began to appear in some of these structures approximately 3 to 4 days after they had developed. Based on these preliminary observations, the authors concluded that viable satellite cells may be harvested from the rainbow trout and that these cells may differentiate to produce multinucleated, striated myotubes in vitro.
Kinetic analysis of cadmium binding to metallothionein and other intracellular ligands in oyster gills
Authors: Roesijadi G. , Klerks P. L.
Published: June 2005

In the oyster Crassostrea virginica the gill was a primary organ for accumulation of Cd from sea water. Gill Cd concentrations measured after 2 weeks of exposure increased as seawater Cd concentrations increased from 0.03 (the control) to 200 μg Cd · liter−1. Both the cytosolic and particulate fractions of gill tissues were involved in sequestering Cd. The cytosolic Cd was bound mainly to metallothionein (MT), which was most effective at binding Cd at the exposure of 50 μg Cd ·liter−1. The relative importance of binding to the particulate fraction was greatest at the lower exposure of 10 μg Cd · liter−1, at which the amount of Cd bound to MT was relatively low, and at the higher exposure of 200 μg Cd · liter−1, at which the capacity for metallothionein to bind Cd appeared to have been exceeded. Gills excised from oysters exposed continuously to 50 μg Cd · liter−1 for up to 24 days were used in a kinetic analysis of the influence of MT induction on intracellular Cd distribution. Short‐term 109Cd‐uptake experiments at this concentration indicated that MT was induced between 1 and 4 days of exposure. Increased binding rates of Cd to MT were attributed to induction of MT and associated with decreased binding to structures in the particulate and to high‐ and low‐molecular‐weight cystolic fractions. The Cd‐binding rates of the different compartments were ranked as MT > particulate fraction > high‐molecular‐weight cytosolic molecules > low‐molecular‐weight cytosolic molecules once MT was induced. The high Cd‐binding rates for MT coupled with the low turnover rates for MT‐bound Cd indicated that MT was the compartment that governed the dynamics of Cd in the whole gill. The intracellular distribution of Cd could be explained on the basis of competitive binding of Cd to intracellular ligands with varying Cd affinities.
Cardiovascular and metabolic responses during anoxic submergence in the bullfrog with and without maintained extracellular pH
Authors: Warburton Stephen J. , Wasser Jeremy S. , Jackson Donald C.
Published: June 2005

We studied metabolic, cardiovascular, and electrolyte responses of paralyzed bullfrogs to 6 hours of submerged anoxia at 15°C, either with or without maintenance of extracellular pH at preanoxic values by NaHCO3 infusion. There were no differences in arterial PCO2 between acidemic and nonacidemic groups. Lactate appearance in arterial blood, as an indicator of anaerobic metabolic rate, was not significantly different between the anoxic groups, although both were significantly elevated over control. Heart rate in both anoxic groups was similar and significantly lower than in control. During anoxia, both systolic and diastolic pressures fell, and the group with maintained pH fell further. Plasma calcium concentration decreased in both anoxic groups, but the fall was more severe in the group in which pH was controlled. Survival was lower in this group, with a rapid decline in survival after 4 hours of anoxia. We conclude that the fall in extracellular pH seen during anoxia has a protective effect on cardiovascular function that may be partially due to maintenance of relatively high extracellular calcium levels.
Protrusion formation in the cell division‐arrested mutant Tetrahymena thermophila cdaA1: Some rules governing cytoskeletal growth
Authors: Bużańska Leonora , Gregory David W. , Wheatley Denys N.
Published: June 2005

In the cdaA1 temperature‐sensitive mutant cell line of Tetrahymena thermophila, growth occurs at the restrictive temperature of 35°C without proper coordination of cytoskeletal structures, resulting in large and irregularly shaped “monsters.” This disturbed development has helped to elucidate some rules governing cortical morphogenesis in this species.

Within the cdaA1 cortex, the individual ciliary row may grow independently with respect to other parts of the cortex. Local growth of the cortex is morphologically visualized as a local increase in the rate of basal body proliferation and elongation of the longitudinal microtubular (LM) band. It results in looplike, three‐dimensional projections that appear at various parts of the cell cortex. After the apical break of the ciliary row with the parallel LM band, these projections become long, fingerlike, and sharply pointed structures.

During its formation, an individual protrusion does not change its location within the cell latitude and longitude. The row by row autonomy and the intrinsic polarity of growth of the ciliary row have been demonstrated. Analysis of further growth in length revealed that in 90% of cases, the free (‐) end of the anterior segment of the broken ciliary row in a protrusion actively elongates, irrespective of the latitude at which protrusion was located.
Organization of positional information in the axolotl limb
Authors: Gardiner D. M. , Bryant S. V.
Published: June 2005

We have used the phenomenon of position‐dependent growth stimulation, brought about by the confrontation of cells with dissimilar positional values, to reveal the organization of positional information in the center of the upper and lower arms of axolotls. When either humerus or radius was transplanted into either dorsal or posterior positions, extra growth leading to the formation of supernumerary digits occurred following amputation through the graft. However, transplants of humerus or radius into anterior or ventral positions did not lead to the formation of any additional digits. The ulna by contrast was capable of stimulating supernumerary digit formation when transplanted into anterior, posterior, dorsal, or ventral positions. We interpret these results to indicate that the humerus and radius are surrounded by symmetrically arranged anterior and ventral positional values, whereas the ulna is surrounded by a complete asymmetrical set of angular positional values. We use our proposed arrangement for the positional information in the limb center to explain a number of previous experimental findings. In addition, we provide an explanation, in terms of the underlying positional information, for the structural and developmental relationships between the different skeletal elements of the vertebrate limb, and in particular for the anatomical pattern known as Gregory's pyramid.