bluuebunny/crossref_metadata_2025 huggingface dataset:
Metabolism of ovomucoid by the developing chick embryo
Authors: Oegema Theodore R. , Jourdian George W.
Published: June 2005

A glycoprotein resembling ovomucoid was purified from chorioallantoic membranes of 12.5 day chick embryos by a sequential procedure involving zinc chloride precipitation, hydroxylapatite chromatography, and ion exchange chromatography on DEAE‐ and CM‐cellulose. The resulting preparation was homogeneous as indicated by polyacrylamide gel electrophoresis at 3 pH values, isoelectric focusing, ultracentrifugation, and immunochemical analysis. The purified material had an isoelectric point of 4.8, molecular weight of 29,500 and contained 1.6 moles of galactose, 7.7 moles of mannose, 22.8 moles of N‐acetylglucosamine and 0.4 mole of glucose per mole of protein. The ovomucoid fraction inhibited bovine trypsin, forming a 1 to 1 complex on a molar basis, and elicited a positive anaphylactoid response in albino rats at levels as low as 0.5 μg. A specific ovomucoid antiserum was obtained from rabbits that allowed investigation of the mobilization and metabolism of ovomucoid in the developing chick embryo. These studies revealed that between days 12 and 13 of embryo development a progressive migration of ovomucoid occurs from the albumin sac to the amnionic sac. The glycoprotein is then swallowed and transported through the gut to the yolk sac, where it is catabolized by proteases and glycosidases contained in the yolk sac membrane. Between day 12 of embryo development and day 7 after hatching, ovomucoid appeared in the serum of the chick and reached a maximum value of 2.4 mg % on day 18 of embryo development.
Effect of actinomycin D on protein synthesis by delayed implanting mouse embryos in vitro
Authors: Weitlauf Harry M.
Published: June 2005

Blastocysts were collected from the uteri of intact or ovariectomized mice and incubated with or without actinomycin D in a medium containing [14C] amino acids. In the absence of actinomycin D the rate of amino acid incorporation by blastocysts from intact mice (i.e., normal embryos) was constant; the rate of amino acid incorporation by blastocysts from ovariectomized mice (i.e., delayed implanting embryos) was initially low and increased to the normal value after four hours in vitro. In the presence of actinomycin D the rate of amino acid incorporation by normal embryos was only slightly reduced but the expected increase in the rate of amino acid incorporation by delayed implanting embryos was completely blocked. It is suggested that metabolic “activation” of delayed implanting mouse embryos requires the synthesis of new RNA.
Transport, capacitation and fertilizing ability of epididymal spermatozoa
Authors: Overstreet J. W. , Bedford J. M.
Published: June 2005

Equal numbers of rabbit spermatozoa from the proximal cauda epididymidis and ejaculate of the same male were mixed and inseminated intravaginally. Their competitive performance in the same female was evaluated by identification of the two populations with x‐irradiation marking (fertilizing spermatozoon) and fluorescein isothiocyanate labelling (spermatozoa in the uterus and egg vestments). Following such mixed inseminations, epididymal spermatozoa from thirteen males fertilized 48% of 251 eggs recovered 50 hours after HCG injection and comprised 55%, 59% and 73% of spermatozoa in the perivitelline space, zona pellucida and mucin layer. When mixed spermatozoa from eight other males were inseminated 5 hours after HCG and the eggs were recovered 8 hours later (13 hours after HCG), epididymal spermatozoa accounted for 53% of the perivitelline and zona spermatozoa in 108 eggs and more than 50% of the uterine spermatozoa in seven of fifteen females. Cleavage of eggs fertilized by spermatozoa from the distal corpus epididymidis and ejaculate of the same male (eight males) was compared by insemination of the respective sperm populations into contralateral oviducts of the same female (sixteen females). There was no significant difference in the level of fertilization or the stage of cleavage 27 hours after insemination and HCG, whether eggs were fertilized by epididymal or ejaculated spermatozoa. These results indicate that once epididymal spermatozoa have acquired the capacity to penetrate the egg, they do not differ from ejaculated spermatozoa in their transport, capacitation, fertilizing ability or competence to sustain development of the egg to the sixteen cell stage.
Meiotic maturation of the mammalian oocyte in vitro: Effect of dibutyryl cyclic AMP on protein synthesis
Authors: Stern Samuel , Wassarman Paul M.
Published: June 2005

Mouse oocytes arrested in dictyate of the first meiotic prophase by dibutyryl cyclic AMP accumulated exogenous valine at the same rate as oocytes undergoing meiotic maturation. The apparent rate of protein synthesis and the spectrum of proteins synthesized were not significantly affected by the presence of dibutyryl cyclic AMP in the culture system. These results suggest that cytoplasmic maturation of the mammalian oocyte proceeds independently of nuclear progression during the period required for completion of the first meiotic division in vitro.
Observations on the effect of human chorionic gonadotrophin on the antler cycle of fallow deer
Authors: Jaczewski Zbigniew , Michalakowa Wieslawa
Published: June 2005

Three experiments on the administration of HCG to fallow deer bucks are described and analysed together with another experiment described earlier. In two cases the administration of HCG was begun before antler shedding and resulted in retardation of their loss and in an inhibition of new growth. The next antlers were of a smaller size. These effects can be attributed to the influences of HCG on testosterone secretion by the testes.

In two other experiments the administration of HCG was begun on the day the antlers were shed. In one case antler growth was stopped completely and no anti‐HCG antibodies were detected in blood. In the second case the antlers grew in spite of HCG injections and a high titre of antibodies was detected in the blood. The anti‐HCG antibodies were only detected in the buck which received HCG injections a second time after a four‐year interval.
Intracellular actions of 5‐hydroxytryptamine on the bivalve myocardium. I. Adenylate and guanylate cyclases
Authors: Higgins William J.
Published: June 2005

The effects of the neurotransmitters 5‐hydroxytryptamine (5HT) and acetylcholine (ACh) on the adenylate and guanylate cyclase activities in the ventricles of two species of bivalve molluscs, Mercenaria mercenaria and Macrocallista nimbosa, were examined. 5HT increased molluscan adenylate cyclase activity and intracellular cyclic AMP; ACh had no effect. Neither of these agents significantly altered ventricular cyclic GMP. A positive correlation between the excitatory action of 5HT and the simultaneous increase in intracellular cyclic AMP strongly suggests that this nucleotide mediates 5HT excitation. This proposal is further supported by experiments on ventricles of Modiolus demissus granosissimus that are depressed by 5HT and exhibit very low levels of adenyl cyclase activity. However, classical pharmacological evidence is lacking; cyclic AMP, dibutyryl cyclic AMP, and phosphodiesterase inhibitors have no effect on the mechanical activity of isolated bivalve ventricles.
Effects of prolactin and growth hormone on protein synthesis in larval and adult frogs (Rana pipiens)
Authors: Snyder Benjamin W. , Frye B. E.
Published: June 2005

Frogs and tadpoles (Rana pipiens) were treated with mammalian prolactin or growth hormone for several days, then injected with 14C‐leucine. Fourteen to sixteen hours later the animals were killed and the amount of label incorporated into protein of muscle, liver, and gut was measured.

Growth hormone stimulated the incorporation of leucine into protein of gastroenemius muscle and small intestine, but not liver, of the frog. Prolactin had no effect on amino acid incorporation in any of these tissues in the frog. Prolactin stimulated the incorporation of leucine into protein of tail muscle, intestine and liver of tadpoles. The effect was not entirely consistent, and was of a smaller magnitude than was expected on the basis of the growth‐promoting effects of prolactin in tadpoles. This problem is discussed. Growth hormone had no effect on protein synthesis in any of these tissues in any experiment.
Selective X‐irradiation of the cartilage at the regenerating margin of rabbit ear holes
Authors: Grimes L. Nichols
Published: June 2005

X‐rays in doses of 3000r inhibit the regeneration which normally occurs from the margins of full thickness rabbit ear holes. Irradiated ears containing unirradiated cartilaginous sheets regenerate new tissue, including cartilage, nearly as well as controls. Selective irradiation of the cartilaginous layer in an otherwise unirradiated ear also permits in‐growth, but no chondrogenes is occurs.
The localization and fate of concanavalin a in amoebae of the cellular slime mold, Dictyostelium discoideum
Authors: Gillette Martha Ulbrick , Dengler R. E. , Filosa M. F.
Published: June 2005

Two different methods for the localization of Con A indicate that this lectin is bound to the surface of Dictyostelium discoideum amoebae. Redistribution of the Con A receptors occurs both on cells in suspension and cells moving on an agar surface. Internalization of the Con A does not occur.
The ultrastructure of regeneration in the severed newt optic nerve
Authors: Turner James E. , Singer Marcus
Published: June 2005

Regrowing nerve fibers are seen in the regenerating newt (Triturus viridescens) optic nerve as early as the fourth postoperative day (4 p.o.d.). The first fibers are found growing through gutters, troughs or tunnels formed by glial cell processes which may serve as pathways to direct the fibers. By 6 p.o.d. regenerating nerve fibers exist in scattered “clusters” growing about the path established by the first fibers. By 10 p.o.d. the clustered appearance is replaced by a more uniform distribution throughout the regenerating nerve.

Beginning with 6 p.o.d. there are increasing signs of spontaneous loss of some regenerating axons. By 21 p.o.d. the loss reaches a peak. The loss appears to be accompanied by continued ingrowth of new fibers. Even as late as 117 p.o.d. the optic nerve population is still not stable for there are signs both of continued nerve growth as well as spontaneous axon loss. Glial myelination of regenerated fibers sets in about 117 p.o.d. and proceeds from the initial lesion centrally toward the optic tectum. There appears to be a direct relation between axon diameter and the initiation of myelination.
The hypoglycemic effects of external insulin on fish and frogs
Authors: Munford John , Greenwald Lewis
Published: June 2005

Previous reports of “insulin shock” induced in fish (and frogs) by externally applied insulin have been confirmed. The insulin induced coma can be reversed by either external glucose, sucrose, or epinephrine. Experiments on rainbow trout have shown that the externally applied insulin acts as though it enters the fish in that a typical hypoglycemia is caused. The action of insulin is via the gills and does not require participation of the digestive tract.
Sex reversal in Betta splendens Regan with emphasis on the problem of sex determination
Authors: Lowe Thomas Philip , Larkin Jeanne R.
Published: June 2005

To gain insight into the sex‐determining mechanism of the Siamese fighting fish, Betta splendens, sex‐reversed individuals were bred and the ratios of the spawnings were examined. Sex‐reversal of 245 females was undertaken by ovariectomizing them; of these, 104 became sex‐reversed. Twenty‐three of these latter fish were mated to normal females and eleven spawnings were raised to maturity.

These spawnings resulted in all female broods or mixed broods. Were the male fish heterogametic, a view currently held by some authors, no males would be produced in these spawnings. Thus, male heterogamety was not substantiated in this study.

Contrary to other studies, the experimental sex reversal of females is not a rare event since nearly two‐thirds of the fish that survived the surgery became sex‐reversed.

Gross dissection and histological observation of sex‐reversed fish revealed a regenerated, unpaired duct which remained after the ovaries had been removed. The tissue of the regenerate was testicular and contained active spermatogenesis.

Some alternative methods of sex determination which may apply to the Betta are examined. These include the possibility of two different sex‐determining races, the effects of exogenous factors, and a polygenic system of sex determination.
Avian scale development. V. Ultrastructure of the chorionic epithelium induced by anterior shank dermis from the scaleless mutant
Authors: Sawyer R. H.
Published: June 2005

In combination with dermis from the anterior shank skin of the scaleless mutant, the chorionic epithelium forms an epidermis whose ultrastructural features are indistinguishable from those seen along the inner surface of normal scales and along the anterior shank of the scaleless mutant.
Xenoplastic combinations between chick chorionic epithelium and fetal monkey dermis
Authors: Sawyer R. H.
Published: June 2005

Fetal monkey dermis from the sole of the foot or ear induces the chick chorionic epithelium (CE) to form an epidermis that histologically resembles chick rather than monkey. These results support the conclusion that in epithelial‐mesenchymal interactions between animals of different vertebrate classes the epithelium responds in a species‐specific manner. Differences were noted, however, in the response of the avian CE to either the sole or ear dermis.
Orientation of homing pigeons: Direct sight of sun not necessary
Authors: McDonald Dennis L.
Published: June 2005

Homing pigeons do not need to see the sun directly in order to orient in a Kramer‐type cage. Five homing pigeons were directionally trained in the traditional manner with a clear view of the sky and sun overhead. They were then tested while wearing a sun shade which prevented them from seeing any of the sky out of the top of the cage. All of the birds were able to maintain their orientation. Shadows on the floor of the apparatus may have provided cues. These results suggest a mechanism pigeons may use to obtain information from the sun, that is, by looking at shadows on the ground. Experiments of a similar nature with free‐flying birds are needed.
Gas transport and blood acid‐base balance in diving sea snakes
Authors: Seymour R. S. , Webster M. E. D.
Published: June 2005

The values of hemoglobin concentration, Hb‐O2 affinity and buffering capacity of the blood of six sea snake species considerably overlap values from terrestrial squamates. Decreased blood pH had little effect on the P50 but increased the n‐value of Hb‐O2 equilibrium curves.

The O2 saturation of blood in the dorsal aorta varied between about 30 and 70% during voluntary diving in Acalyptophis peronii and Lapemis hardwickii. Voluntary dives ended when the lung Po2 was about mm Hg and the arterial Po2 about 30 mm Hg indicating that roughly half of the O2 reserves had been used. In conjunction with relatively stable blood lactate concentration and pH, this indicates that voluntary dives occurred largely aerobically. In contrast, forced dives resulted in depletion of O2 reserves and large changes in blood acidbase balance. Long recovery periods following forced dives are inconsistent with field observations and thus suggest that extensive anaerobic metabolism does not normally occur in sea snakes. Bradycardia was not evident during forced dives.

Large differences in Po2 between the lung and dorsal aorta indicated considerable right to left shunting either in the heart or in the lung. Venous blood represented over 50% of the systemic flow when there was considerable O2 in the lung. Therefore blood Po2 may remain relatively low despite elevated lung Po2 resulting from diving. In view of substantial capability for extra‐pulmonary gas exchange, high shunting reduces the possibility of losing O2 through the skin and also may help prevent decompression sickness following deep dives.
Development of parthenogenetic membranes in double‐yolked and injected chicken eggs
Authors: Sarvella Patricia , Gehman Melvin
Published: June 2005

Development of parthenogenetic eggs is expressed in a Dark Cornish stock by either membrane or embryo formation. Double‐yolked eggs have membranes developing in zero, one, or two yolks. The incidence of double‐yolked eggs with two membranes was higher than expected when compared with the incidence of single‐yolked eggs from the same hens. Membrane formation was increased over that of the controls by injecting saline, Ringer's solution, or ground crude membranes. Yolk and membranes filtered through a 3 μ filter or autoclaved did not increase membrane formation over that of the controls. Fertile membranes behaved like parthenogenetic membranes.
Alkaline phosphatase isozymes of Xenopus laevis embryos and tissues
Authors: Maekawa H. , Yamana K.
Published: June 2005

Alkaline phosphatase was obtained by treating embryos of Xenopus laevis with n‐butanol at different developmental stages from gastrula to tadpole; the enzyme was also obtained from adult kidney, liver, and intestinal mucosa. Purification was carried out by gel filtration and polyacrylamide gel electrophoresis.

The enzyme activity is chromatographically spearated into two peaks, with molecular weights of approximately 200,000 and 400,000. Alternatively, two groups may be characterized on the basis of their electrophoretic mobilities, which correspond to the different molecular weight classes.

Effects of pH, temperature, inhibitors, and substrate concentration were studied. The kinetic and physical properties of the two alkaline phosphatase isozymes are similar, and are comparable to the properties reported for this enzyme from other vertebrates. Alkaline phosphatase activity increased sharply at the gastrula stage and reached a plateau at the late tailbud stage. During this period there was an 18‐fold increase in activity.
Fertilizing ability of mouse sperm from different epididymal regions and after washing and centrifugation
Authors: Hoppe P. C.
Published: June 2005

The ability of caput, corpus, and cauda epididymal and vasa deferentia mouse sperm to fertilize eggs in vitro was investigated. Cauda epididymal sperm fertilized 45 of 54 ova, whereas caput and corpus sperm fertilized a negligible number of ova, thus indicating their immaturity. Vasa deferentia sperm fertilized only 10 of 52 ova and their reduced fertility may be due to aging in vivo. No difference in preimplantation development of the resulting zygotes with respect to the sperm source was observed.

Three centrifugations and resuspensions of cauda epididymal sperm in fresh medium did not affect their fertilizing ability. I conclude that fertilization in vitro can occur after removal of epididymal secretions.
Feulgen microspectrophotometric analysis of deoxyribo‐nucleoprotein organization in larval and adult freshwater sponge nuclei
Authors: Harrison Frederick W. , Cowden Ronald R.
Published: June 2005

Microspectrophotometric measurements of nuclei of adult choanocytes and archeocytes and larval archeocytes and flagellated ectodermal epithelia from stages III and IV were undertaken on tissues from the freshwater sponge, Eunapius fragilis (Leidy). The condensed nuclei of differentiated choanocytes and stage IV flagellated epithelial cells presented integrated extinction values about 64% of those obtained for either adult or larval archeocytes. This suggests that such measurements represent sensitive indicators of deoxyribo‐nucleoprotein‐complex organization; thus, nuclear differentiation. Further, no large population of G2 (4C) nuclei was found among these populations as has been reported in two classes of coelenterates.
Glycogen metabolism in the developing chick glycogen body: Functional significance of the direct oxidative pathway
Authors: Benzo Camillo A. , De Gennaro Louis D. , Stearns Susan B.
Published: June 2005

Glucose‐6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase, and glucose‐6‐phosphatase were quantitatively determined for the first time in glycogen body tissue from late embryonic and neonatal chicks. For comparative purposes, the activities of these enzymes were examined also in liver and skeletal muscle from pre‐ and post‐hatched chicks. The present data show that both the embryonic and neonatal glycogen body lack glucose‐6‐phosphatase, but contain relatively high levels of glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase. The activity of each dehydrogenase in either embryonic or neonatal glycogen body tissue is two‐ to five‐fold greater than that found in muscle or liver from pre‐ or post‐hatched chicks. The relatively high activities observed for both dehydrogenases in the glycogen body, together with the absence of glucose‐6‐phosphatase activity in that tissue, suggest that the direct oxidative pathway (pentose phosphate cycle) of glucose metabolism is a functionally significant route for glycogen utilization in the glycogen body. It is hypothesized that the glycogen body is metabolically linked to lipid synthesis and myelin formation in the central nervous system of the avian embryo.
A reexamination of cleavage patterns in eutherian mammalian eggs: Rotation of blastomere pairs during second cleavage in the rabbit
Authors: Gulyas Bela J.
Published: June 2005

The pattern of cleavage was examined during second and third furrowing of the rabbit egg. Two‐cell eggs, collected just prior to onset of second cleavage, were continuously observed in a culture chamber, which was kept at 37°C. Semi‐cinematographic techniques were used to photograph progressive stages of cleavage. It was demonstrated that the pattern of cleavage in the rabbit differs from that in the sea urchin, because the blastomeres at the 4‐cell stage are arranged crosswise in the former, while they are situated next to each other in the latter. The crosswise arrangement of the blastomeres in the rabbit at the 4‐cell stage is a consequence of a 90° rotation of the polar axis in one hemisphere of the egg. Subsequently, due to the rotation of the original polar axis in one hemisphere, the third cleavage plane through one half of the egg is transverse to the third cleavage plane through the other half. Evidence is provided to show that the crosswise configuration of blastomeres at the 4‐cell stage occurs in other eutherian mammals. It is proposed that this rotational cleavage pattern be recognized as distinct from those of radial, spiral and bilateral.
The influence of environmental salinity on hemocyanin function in the blue crab, Callinectes sapidus
Authors: Weiland A. L. , Mangum C. P.
Published: June 2005

The effects of inorganic ions and of the hydrogen ion on oxygen‐binding properties of most respiratory pigments are opposite. The addition of salt to the medium increases oxygen affinities, and the addition of H+ decreases oxygen affinities of crustacean hemocyanins. These oxygenation properties, as observed in vitro, suggest that the oxygen‐transport system must adapt to ionic changes in the blood.

In fact, decreases in the salt concentration of the blood of estuarine blue crabs are accompanied by increases in pH, probably resulting from the input of ammonia produced in deamination of the intracellular pool of free amino acids as the cells conform to osmotic changes in body fluids. The result is a stability of hemocyanin function until the blood becomes very dilute.

As the acclimation salinity is reduced from 35 to 15 o/oo, the ionic effects on respiratory transport are balanced and there is no change in total oxygen uptake. At 5 o/oo salinity, however, the higher blood pH is manifested in an elevation of the total oxygen concentration of prebranchial blood, probably because the Bohr shift is no longer opposed by a critical level of salt in the blood. Under these conditions the role of hemocyanin in aerobic respiration is reduced at high environmental oxygen levels, but it may be enhanced in hypoxic waters.
Pineal and serum melatonin at midday and midnight following pinealectomy or castration in male rats
Authors: Pang Shiu Fun , Ralph Charles L.
Published: June 2005

Melatonin has been extracted by chloroform from rat serum and quantified by the Rana pipiens tadpole bioassay. Like pineal melatonin, serum melatonin was high at mid‐dark and low at mid‐light. This finding suggests a diurnal rhythm of serum melatonin in the rat. Serum samples obtained at middark had melatonin levels ranging from 0.02 to 0.05 ng per ml of serum. When rats were pinealectomized, melatonin activity in the serum was abolished. Thus, rat serum melatonin may originate primarily from the pineal. There was no significant change in pineal melatonin content nor in serum melatonin concentrations 7 or 12 days following orchidectomy.
Anhydrobiosis in nematodes: Evaporative water loss and survival
Authors: Crowe John H. , Madin K. A. C.
Published: June 2005

Nematodes, Aphelenchus avenae, can be induced to become anhydrobiotic by drying in aggregates (pellets) (>90 mg wet weight) at 97% relative humidity (RH). When the rate of weight loss exceeds 3% hr−1 survival is low.

The number of animals in a pellet that survive exposure to dry air increases with time at 97% RH.

The time required for recovery is shortened by rehydration at high humidities before the animals are placed in water and advances with the length of time they are in dry air.

The proportion of animals recovering in water that will survive rapid dehydration decreases with the time they are in water.

A hypothetical scheme for the events of the induction of anhydrobiosis and recovery is presented.
Anhydrobiosis in nematodes: Carbohydrate and lipid metabolism during dehydration
Authors: Madin K. A. C. , Crowe John H.
Published: June 2005

1. Changes in the chemical composition of pellets of the nematode Aphelenchus avenae were studied as the worms experienced evaporative water loss during 72 hours at 97% RH.

2. Lipid content declines rapidly during the first 24 hours, and decreases to about 60% of the original by the end of 72 hours.

3. Glycogen content declines to about 50% of original by the end of 24 hours, and to 10% of original by 72 hours.

4. Glucose content remains constant.

5. Glycerol and trehalose contents both increase rapidly, reaching about 700% of the 24‐hour content by the end of 72 hours, in each case.

6. Strong correlations between survival in dry air and glycerol and trehalose contents were observed.
Mast cell histamine and ovarian follicular growth in the lizardAnolis carolinensis
Authors: Jones Richard E. , Tokarz Richard R. , Roth Jan J. , Platt James E. , Collins Allan C.
Published: June 2005

The hypothesis is proposed that histamine released from mast cells in the theca of ovarian follicles increases thecal hyperemia and vessel permeability, and thus plays a role in follicular growth inAnolis carolinensis. Mast cells are present in the stroma and theca, and the number of thecal mast cells increases as follicles grow. The levels of histamine in follicular walls varies with follicular size. Histamine causes vasodilatation of thecal vessels. Antihistamine blocks the effects of histamine and, when given alone, stimulates vasoconstriction. Antihistamine also blocks estradiol‐induced growth of large follicles. These findings are consistent with the above hypothesis.
Effect of limb regeneration on size increase at molt of the shore crabs Hemigrapsus oregonensis and Pachygrapsus crassipes
Authors: Kuris Armand M. , Mager Marc
Published: June 2005

Size increase at molt is reduced following multiple limb regeneration in the shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes. Limb loss per se does not influence postmolt size. Effect of increasing number of regenerating limbs is additive. Postmolt size is programmed early in the premolt period of the preceding instar and is probably not readily influenced by water uptake mechanics at ecdysis. A simple model for growth, molting, and regeneration in heavily calcified Crustacea is developed from the viewpoint of adaptive strategies and energetic considerations.
Initiation of meiotic maturation in Xenopus laevis oocytes by the combination of divalent cations and ionophore A23187
Authors: Wasserman William J. , Masui Yoshio
Published: June 2005

Meiotic maturation was induced in Xenopus laevis oocytes when the external Ca++ or Mg++ion concentration was raised above 5 mM in the presence of the ionophore. Ionophore‐divalent cation‐induced maturation appears to be due to the stimulation of the oocyte itself. Cytoplasm of responding oocytes induced maturation when microinjected into ovarian oocytes. Cycloheximid, an inhibitor of progesterone‐induced maturation, inhibited the maturational response induced by the ionophore and divalentications. Ethidium bromide, an inhibitor of the follicular response to human chorionic gonadotropin, had no effect. The possible roles that Ca++ and Mg++ may play in the initiation of maturation are discussed.
The effects of cold stress on fluctuating asymmetry in the dentition of the mouse
Authors: Siegel Michael I. , Doyle William J.
Published: June 2005

Albino mice (BALB), conceived, born, and raised at 10° C exhibit significant changes in the magnitude of fluctuating dental asymmetry. These results confirm the hypothesis that the dentition responds to the general stress syndrome.
Evidence that insect dorsal unpaired medican (DUM) neurons are octopaminergic
Authors: Hoyle Graham
Published: June 2005

The dorsal unpaired median neuron innervating the extensortibiae (DUMETi) of locusts and grasshoppers, as well as some other DUM neurons, cause long‐term inhibition of the slow intrinsic rhythm of contraction of the muscle by releasing a neurohumoral agent. Large, (600 – 1900 A), dense‐core vesicles are present in the nerve terminals. The inhibitory action is mimicked by infusion into the leg of a minute (0.01 ml.) drop of locust saline containing a very low concentration (10−6 M) of dopamine or noradrenaline, or an extraordinarily low concentration of octopamine (2.5 × 10−9 M). The amplitude and frequency of the contractions slowly return to normal Neither the cell body nor the neuron fluoresces with the Falck‐Hillarp treatment, even after a period of ligature has caused an accumulation of vesicles. Octopamine does not fluorescence with this treatment. Accordingly, it is suggested that this neuron, and the other efferent DUM neurons, are octopaminergic.
Polymerization of sperm actin in the presence of cytochalasin‐B
Authors: Sanger Joseph W. , Sanger Jean M.
Published: June 2005

The polymerization of globular actin to fibrous actin which occurs when sperm are activated, was not inhibited by cytochalasin‐B. The acrosomal filaments and its component actin filaments formed in the presence of cytochalasin‐B; and once formed, the actin filaments did not depolymerize when exposed to cytochalasin‐B.
Comparative strategies in the investigation of neural networks
Authors: Kennedy Donald
Published: June 2005

Comparative studies on nervous systems, though infrequently undertaken for the purpose of comparison, have yielded some important generalities about the formats of nervous networks, and about the cell biology of certain neural types. In the first category, it is clear that convergent evolutionary processes arrived at very similar networks to accomplish reciprocal and lateral inhibition, and load‐compensation in “resistance reflexes.” A newer general network format is described, command‐derived inhibition, in which the central nervous elements controlling a rapid movement deliver presynaptic inhibition to the terminals of sensory neurons that carry reafferent excitation from the movement. It is argued that such circuits occur in several groups of animals, and that they include as a special class the efferent inhibitory neurons innervating acoustico‐lateralis receptors in vertebrates.

The properties of circuit elements that now seem to constitute useful generalizations include size principle (the inverse relationship between size and excitability in a variety of neurons), and the late differentiation of sensory neurons, failure to decussate, and their inability to mediate inhibition. Many other generalities have emerged, only to fall; one conclusion from such searches is that many supposedly “basic” properties of cell types or neural circuits are in fact not phylogenetically conservative, however much the physiologist may expect them to be.
Identified neurons and the future of neuroethology
Authors: Hoyle Graham
Published: June 2005

Ethologists have, in effect, opened up a vast area for physiological study by drawing attention to fixed action patterns and other stereotyped forms of instinctive behavior and by implying common physiological mechanisms underlying common behaviors in related species. Examples of such behavior in invertebrates are considered, to establish guidelines as to which behaviors may most profitably be studied by comparative neurophysiologists. These include: escape swimming and other locomotor patterns, and courtship behavior. The chosen forms should be ones in which there is a good prospect of recording intracellularly from the central neurons involved in the behavior. These neurons must be ones that can be identified individually if the biophysical events that cause the behaviors are to be described in critically acceptable terms. It is desirable that both genetic and developmental research be combined with the behavioral and physiological studies. Advantages and disadvantages of various types of invertebrates are compared, and it is concluded that a large insect offers the best overall prospects for neuroethology.
Comparative studies of purinergic nerves
Authors: Burnstock G.
Published: June 2005

Purinergic nerves supply the gastrointestinal tract of vertebrates, including fish, amphibians, reptiles and birds, as well as mammals. Their cell bodies are located in Auerbach's plexus and their axons extend in an anal direction before innervating mainly the circular muscle coat. In the stomach they are controlled by preganglionic cholinergic fibres of parasympathetic origin.

They are involved in “receptive relaxation” of the stomach, “descending inhibition” in peristalsis and reflex relaxation of oesophageal and internal anal sphincters.

The terminal varicosities of purinergic nerves are characterised by a predominance of “large opaque vesicles,” which can be distinguished from the “large granular vesicles” found in small numbers in both adrenergic and cholinergic nerves. Stimulation of purinergic nerves with single pulses produces hyperpolarisations of up to 25 mV (inhibitory junction potentials) in smooth muscle cells. These potentials are unaffected by atropine, adrenergic neuron blocking agents or sympathetic denervation, but are abolished by tetrodotoxin. The “rebound contraction” which characteristically follows cessation of purinergic nerve stimulation is probably due to prostaglandin.

Evidence that ATP is the transmitter released from purinergic nerves includes: (1) synthesis and storage of ATP in nerves; (2) release of ATP from the nerves when they are stimulated; (3) exogenously applied ATP mimicking the action of nerve‐released transmitter, both producing a specific increase in K+ conductance; (4) the presence of Mg‐activated ATPase, 5′‐nucleotidase and adenosine deaminase, enzymes which inactivate ATP; (5) drugs (including quinidine, some 2‐substituted imidazolines, 2‐2′pyridylisatogen and dipyridamole) which produce similar blocking or potentiating effects on the response to exogenously applied ATP and nerve stimulation.

Speculations are made about the evolution and development of the nervous system, including the possibility that purinergic nerves are a primitive nerve type.
Disruption of normal forelimb regeneration in adult Notophthalmus viridescens by sublethal concentrations of trypan blue
Authors: Dearlove G. E. , Lopez S. , Dresden M. H.
Published: June 2005

The effects of the vital dye trypan blue (TpB) on the regeneration of amputated newt forelimbs were examined. Administration of the dye (10 μg/g body weight) via IP injection during the early wound healing and dedifferentiation phases of regeneration inhibited the normal regenerative response. The accumulation phases of regeneration are similarly halted but only by greater concentrations of TpB (50 μg/g body weight) while redifferentiation and morphogenesis are only affected by still greater concentrations of the dye (100 μg/g body weight). In addition to abolishing the regenerative response, low levels of TpB were also capable of inducing skeletal abnormalities in the regenerates as might be expected from previous reports on the teratogenicity of the dye. The in vitro action of newt hyaluronidase (as well as purified testicular hyaluronidase) on hyaluronate was diminished by TpB, with virtually complete inhibition observed at initial reaction mixture concentrations of 100 μg/ml. The results of this study suggest that TpB acts to disrupt the normal regenerative response by preventing dedifferentiation and remodeling, perhaps by inhibition of various necessary lytic enzyme functions or by interference with normal intercellular communications.
Hydrolysis of the hen egg vitelline membrane by cock sperm acrosin and other enzymes
Authors: Ho Jenny J. L. , Meizel Stanley
Published: June 2005

A technique utilizing Pregnant Mare's Serum Gonadotropin and Human Chorionic Gonadotropin treatment of hens (Gallus domesticus), followed by manual ovulation of the excised follicles, was developed to obtain a large number of mature ova. The intact ova were used to test whether acrosin, partially purified from the spermatozoa of the cock (Gallus domesticus), partially purified rabbit testicular acrosin and commercial preparations of several hydrolytic enzymes could dissolve the inner vitelline membrane. Enzymes were applied to pieces of filter paper placed on the ovum. Cock acrosin and endopeptidases such as trypsin, chymotrypsin, collagenase and elastase hydrolyzed the membrane whereas exopeptidases such as leucine aminopeptidase and carboxypeptidase A did not. Phospholipase A, sulfatase, hyaluronidase, β‐glucuronidase and rabbit testicular acrosin also failed to hydrolyze the membrane. Cock acrosin hydrolysis of the ovum surface was inhibited by soybean trypsin inhibitor. The surface of the ovum over the germinal disc region was hydrolyzed more quickly by cock acrosin than the surface over other regions of the ovum.

Acrosin from cock sperm caused the release of trichloroacetic acid soluble material absorbing at 280 nm from sonicated preparations of inner vitelline membranes. Hydrolysis was greatest at pH 8.0 and was inhibited by soybean trypsin inhibitor.
Development of locomotor behavior in wild type and spastic (sp/sp) Axolotls, Ambystoma mexicanum
Authors: Ide Charles F. , Tompkins Robert
Published: June 2005

The homozygous recessive spastic mutant found in the Mexican axolotl shows violent coiling and thrashing behavior when subjected to strong tactile or electrical stimulation. In order to establish the time of onset of the first behavioral manifestation of the spastic gene, an ethological analysis of the ontogeny of swimming behavior in mutants and wild type siblings was undertaken. The locomotor patterns shown by embryos in response to an electrical stimulus were analyzed quantitatively from the embryonic early flexure stage through the larval early feeding stage. Spastic larvae failed to show dorsal‐up swimming frequencies equal to those of sibling controls from day 12 (Harrison stage 40) of development indicating a lack of equilibrium. Both spastics and their siblings showed “sinusoid swimming” and “coiling” behavior in response to an aversive stimulus through day 18 (Harrison stage 46, early feeding stage) of development. From day 18, wild type siblings abruptly decreased “coiling” behavior and showed strong “escape swimming” in response to an intense stimulus. Spastics never developed “escape swimming” patterns but retained a mixture of “sinusoid swimming” and “coiling” patterns characteristic of pre‐feeding stage larvae.
Programmed collagen synthesis during postembryon development of the nematode Panagrellus silusiae: effect of transcription and translation inhibitors
Authors: Pasternak J. , Leushner J. R. A.
Published: June 2005

During postembryonic development of the free‐living nematode Panagrellus silusiae, collagen synthesis is temporally regulated with an increase in production occurring prior to each molt. Under certain conditions when actinomycin D treatment blocked both growth and ecdysis the programmed synthesis of collagen was not altered. Thus, the programming of postembryonic collagen synthesis is not perforce geared to either growth or ecdysis. Actinomycin D inhibits transcription by 70% in this organism when growth is completely blocked. Additional agents (viz., cordycepin and α‐amanitin) that are known to interfere with messenger RNA utilization and production in other systems disrupt the normal pattern of collagen synthesis and prevent both growth and ecdysis in Panagrellus. Each peak of collagen synthesis, therefore, requires new RNA synthesis, presumably messenger RNA. Two known inhibitors of translation (puromycin and cycloheximide) perturb the regulated pattern of collagen production as well as growth and ecdysis. We infer that the formation of a new cuticle at each molt is dependent upon de novo collagen synthesis during each intermolt period and that growth and ecdysis require ongoing translation throughout postembryonic development.
Failure of gonadotropins to induce in vitro maturation of mouse oocytes treated with dibutyryl cyclic AMP
Authors: Nekola Mary V. , Smith Dianne Moore
Published: June 2005

In sufficient concentration, dibutyryl cAMP (DBC) prevents the spontaneous in vitro maturation of mouse oocytes. The effects of luteinizing hormone (LH) and follicle stimulating hormone (FSH) on this inhibition were tested in an oil‐free chamber‐slide culture system. Mouse oocytes devoid of cumulus cells were incubated in the presence of DBC and/or gonadotropins. Oocytes cultured with follicle cells were similarly treated. Whether follicle cells were present or absent, DBC (100 or 50 μg/ml) prevented germinal vesicle breakdown in more than 95% of the oocytes cultured. Neither LH nor FSH in a wide range of concentrations acted directly on the oocytes or indirectly through the follicle cells to initiate maturation in oocytes incubated with 100 μg DBC/ml. The combination of LH (5 μg/ml) and FSH (10 μg/ml) was also ineffective in overcoming the block induced by either 100 or 50 μg DBC/ml. Maturation of oocytes in each of the DBC‐free LH or FSH treatments was comparable to that occurring in control medium which did not contain exogenous gonadotropins or DBC. It was concluded that cultured oocytes treated with DBC are not a satisfactory model for studying the steps by which gonadotropins trigger the resumption of meiosis in mammalian oocytes.
Mitosis in the intact and regenerating planarian Dugesia mediterranea n.sp. II. Mitotic studies during regeneration, and a possible mechanism of blastema formation
Authors: Baguñà Jaume
Published: June 2005

In planarian regeneration mitosis occurs in both anterior and posterior blastemas. The mitotic increase is visible as early as one hour after amputation, reaches a rapid first maximum at 5–12 hours, a relative minimum at 24–30 hours, and a higher and longer second maximum at two to four days depending on body size, level of amputation, and on whether blastema is anterior or posterior. The spatial dynamics of mitosis show a rapid and high mitotic increase in the distal regions but not in the proximal regions. Later, the proliferative zone shifts in sucessive mitotic waves to more proximal regions, paralleling the formation of the head ganglia and nerve cords.

These results do not agree with theories of blastema formation through neoblast migration or through cell dedifferentiation, in as much as the local proliferation of neoblasts encountered is sufficiently high and early to account for the number of blastema cells found during period of regeneration. Therefore, we suggest that blastema formation during planarian regeneration occurs mainly through local neoblast proliferation.

These results and the data obtained on regeneration rates enable us to suggest that nervous tissue may be one of the factors responsible for the differing mitotic increases found. Since neoblasts are the only planarian cells capable of mitosis, we suggest that neoblast proliferation could be under nervous tissue control through some stimulatory substance (s) released from the nerve terminals. The implications of this hypothesis for the maintenance of axial polarity are also discussed.
Studies on immunoglobulins of Xenopus borealis, Xenopus clivii and Xenopus muelleri
Authors: Hadji‐Azimi Irandokht , Brandt Daniel , Bossus André , Michea‐Hamzehpour Mehrbanou
Published: June 2005

Following immunization with human IgG three species of anuran amphibians, Xenopus borealis, Xenopus clivii and Xenopus muelleri, were found to synthesize two molecular populations of antibodies associated with 19S and 7S fractions of the sera. These antibodies, designated high (HMW) and low (LMW) molecular weight immunoglobulins, were isolated and their constituent heavy (H) and light (L) polypeptide chains separated following extensive reduction and alkylation in a relative yield of about 70% and 30% respectively. The molecular weights of H and L chains of the three species were determined by SDS‐acrylamide gel electrophoresis. The L chains from both molecules in the three species had a molecular weight of about 26,000. The H chains of the HMW and LMW immunoglobulins had a molecular weigh of about 73,000 and 63,000 respectively. The two populations of immuno globulins were analysed in immunodiffusion plates using rabbit antisera to LMW immunoglobulins. The HMW immunoglobulins were found to be antigenically deficient with respect to LMW immunoglobulins. From these results it was judged that the two populations in each species belonged to distinct classes. The antigenicities of the LMW and HMW immunoglobulins of different species within the genus Xenopus were compared.
Evidence for the role of a trypsin‐like enzyme in the hamster sperm acrosome reaction
Authors: Meizel Stanley , Lui Chung W.
Published: June 2005

Acrosome reactions occurring in vitro in hamster sperm capacitated by bovine follicular fluid were severely inhibited by four synthetic trypsin inhibitors and by Zn2 +. Three polypeptide trypsin inhibitors and a synthetic chymotrypsin inhibitor did not inhibit the acrosome reaction, and Ca2 + overcame the inhibition by Zn2. These results suggest that a trypsin‐like enzyme (possibly acrosin) plays a role in the acrosome reaction.
Octopamine: Presence in firefly lantern suggests a transmitter role
Authors: Robertson Harold A. , Carlson Albert D.
Published: June 2005

The lantern of the adult firefly is innervated by a nerve supply with endings similar to other known monoaminergic nerves. However, catecholamines could not be detected in the nerve endings and noradrenaline and adrenaline were relatively weak agonists in eliciting a flash of light when applied to the lantern in vitro. Firefly lanterns were assayed for octopamine using a sensitive, specific enzymatic assay in which octopamine is enzymatically converted to 3H‐synephrine and quantitated by liquid scintillation counting. The presence of substantial amounts (125 ng/g tissue) of octopamine was demonstrated and confirmed by thin layer chromatography. On the basis of this and earlier work, it is suggested that the nerves to the firefly lantern are octopaminergic.