bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in morphology and cell proliferation during vitamin A‐lnduced mucous metaplasia of developing chick scale cultured in vitro
Authors: Tanaka Shoji
Published: June 2005

Throughout the process of vitamin A (V‐A)‐induced mucous metaplasia of the scale epidermis of a 12‐day chick embryo, changes in the activities of cell proliferation were investigated in reference to morphological changes. In both the control and V‐A cultures after 5 days, a dynamic steady state was established among the stratified layers which differentiated into keratinizing epidermis during the first 7 days.

In the control, cell proliferates within only the basal layer and the cell cycle time, except Tg2, increased during 30 days of culture. In the V‐A culture, this tendency was reversed in each parameter between day 10 and day 13, when symptoms of mucous metaplasia became morphologically prominent. On day 13 in the V‐A culture, superficial cornified cell layers were sloughed off as whole sheets and concurrently DNA synthesis was reactivated throughout the entire cell layers of the epithelium.

The correlation between two of five cell cycle times (Tgc, Tg1, Ts, Tg2, Tm) was statistically treated as linear regression lines and gave highly significant coefficients in every case. The regression coefficients between Ts and Tgc and Ts and Tgl in V‐A culture are significantly (P < 0.01) smaller than those in the control. It was found that V‐A induced sequential alterations in mucous metaplasia with respect both to morphology and proliferation activity in the epidermis of the chick embryo.
BHC‐lnduced molt inhibition in the fresh water rice field crab (Oziotelphusa senex senex fabricius)
Authors: Reddy P. Sreenivasula , Bhagyalakshmi A. , Ramamurthi R.
Published: June 2005

BHC‐induced molt inhibition in the crab, Oziotelphusa senex senex Fabricius, apparently by triggering the release of molt inhibition hormone (MIH).
Autoradiographic visualization of beta adrenergic receptors in fish melanophores
Authors: Komatsu Koichiro , Yamada Koji
Published: June 2005

Autoradiographic demonstration of beta adrenergic receptors was achieved light microscopically in melanophores of isolated scales of a teleost fish, Oryzias latipes. [3H]hydroxybenzylisoproterenol, a beta adrenergic agonist, and [3H]propranolol, a beta adrenergic antagonist, were used as radioligands. In the autoradiograms, photographic grains of considerably high density were found to be distributed evenly over all parts of the surface of melanophores. Since the density of the grains was observed to decrease significantly in the presence of excess amounts of nonlabeled ligands, the results indicate the actual existence of beta adrenergic receptors in the present melanophores. This substantiates the findings obtained by other physiological and pharmacological methods that beta‐adrenergic receptors may exist and be involved in melanosome‐dispersion response of fish melanophores.
Electrical activities of a type of electroretinogram recorded from the ocellus of a jellyfish, Polyorchis penicillatus (hydromedusae)
Authors: Weber Christian
Published: June 2005

An electroretinogram (ERG), evoked by light stimuli, was recorded from ocelli of Polyorchis penicillatus (Hydromedusae). The ERG is a polyphasic response with a positive potential change at the onset of illumination followed by a slower biphasic pulse, and a positive deflection at the cessation of illumination which is followed by a series of high‐frequency pulses. The most striking features of the initial pulse are its latency‐log intensity relation and the gradation of pulse amplitude with respect to the intensity of the light stimulus and to different wavelengths. Maximum spectral sensitivity lies around 530 nm. Response patterns induced by shadowing and repeated stimulation of light‐ and dark‐adapted ocelli are described. Morphological structures which could give rise to the mass response of the ocellus are discussed.
Pattern development in palleal buds of the polystyelid ascidian, Polyandrocarpa misakiensis: Bud grafting induces bilateral asymmetry conversion through polarity reversal
Authors: Kawamura Kazuo , Watanabe Hiroshi
Published: June 2005

Previous work has shown that the anteroposterior axis and the transverse axis of the palleal buds of some botryllid and polystyelid ascidians develop in a predictable manner, depending on the position of the buds on the parental lateral wall. In the present study, three kinds of homopleural and heteropleural bud grafts were performed to invert the presumptive bud axes. The results show that the polarity of the bud A‐P axis can be inverted with relative ease, depending on the duration of the connection of the bud with a host adult zooid. Concurrently with the reversal of this axis, the normal pattern of body asymmetry is reversed. When both the presumptive anteroposterior and transverse axes are inverted, the future zooid develops the same body asymmetry pattern as its parent. Body asymmetry conversion was induced most efficiently (22.8%) when buds were amputated and grafted with reversed proximodistal axis on the host mantle wall. The polarities of zooid body patterns are transmitted through subsequent (asexual) blastogenic generations. This work shows that the future body pattern of a bud depends on the two axial polarities of its parent.
The relation of Na and Cl extrusion in Opsanus beta, the gulf toadfish, acclimated to seawater
Authors: Kormanik Gregg A. , Evans David H.
Published: June 2005

A model has been proposed by Silva et al. ('77) to describe the manner by which Cl extrusion occurs across the gills of the eel and seawater fish in general. Aspects of the model include (1) passive distribution of Na across the gill surface, and (2) Cl extrusion dependent on Na‐K‐ATPase and thus dependent on the transport of Na.

In order to test various aspects of this model, we examined, using the appropriate radiotracers, the relationship of Na and Cl efflux in the gulf to adfish, Opsanus beta. The model of Silva et al. does not apply to the toadfish because (1) Na cannot be passively distributed across the gills of the toadfish, because the transepithelial potential is several millivolts negative with respect to seawater, and (2) Cl efflux (unlike Na efflux) is not dependent on external K. Additionally, Cl efflux is dependent on the seawater Na concentration, and both Na and Cl efflux are dependent on seawater HCO3. Thus Na and Cl efflux appear to be linked in the toadfish, but not as proposed in the model suggested by Silva et al.
Incorporation of synthesized and dietary hydrocarbons into the cuticle and hepatopancreas of the scorpion Paruroctonus mesaensis
Authors: Hall Richard L. , Hadley Neil F.
Published: June 2005

Measurable amounts of cuticular and hepatopancreas lipids were synthesized by the scorpion Paruroctonus mesaensis from [14C]‐labeled acetate, propionate, mevalonate, and leucine when animals were acclimated to 35°C and incubated for at least 72 hours. Labeled hydrocarbons comprised less than 1.5% of the activity in lipids, with most of the labeled hydrocarbons associated with the hepatopancreas. The hepatopancreas was also the site of most lipid synthesis in scorpions injected with [3H]H0. Incorporation of the latter into hydrocarbons relative to other lipid classes increased from 0.9% in 72 hours to 8.4% by day 10 in fed animals, with slightly higher values in starved scorpions. After 3 months, activity in cuticular hydrocarbons increased coincident with a decrease in hepatopancreas activity. Scorpions maintained on crickets (Acheta domesticus) which contain few n‐alkanes showed a marked decrease in cuticular n‐alkanes after 10 weeks, while scorpions maintained on grasshoppers (Trimerotropis pallidipennis) which are n‐alkane‐rich showed a corresponding increase in their cuticular n‐alkanes. Scorpions fed crickets injected with labeled n‐alkanes (C25, C27, C29) incorporated these unchanged into their cuticular hydrocarbons. These results are evidence that lipid synthesis is consistent with the low metabolic rate of the scorpion and that the synthesized hydrocarbons which slowly accumulated in the cuticle were supplemented by diet‐specific branched and n‐alkanes.
Oocyte maturation in the amago salmon (Oncorhynchus rhodurus): In vitro effects of salmon gonadotropin, steroids, and cyanoketone (an inhibitor of 3β‐hydroxy‐Δ5‐steroid dehydrogenase)
Authors: Young Graham , Kagawa Hirohiko , Nagahama Yoshitaka
Published: June 2005

The effect of partially purified chinook salmon gonadotropin (SG‐G100) and a number of steroids on the induction of germinal vesicle breakdown (GVBD) in amago salmon (Oncorhynchus rhodurus) oocytes (with intact follicle layers) was investigated in vitro. SG‐G100 was effective only at the highest concentration tested (1 μg/ml). 17α,20β‐Dihydroxy‐4‐pregnen‐3‐one (17α,20β‐diOHprog) was the most potent maturation‐inducing steroid tested, followed by 17α‐hydroxyprogesterone. Testosterone or deoxycorticosterone (DOC) enhanced the rate of GVBD in response to SG‐G100. DOC also enhanced the response to 17α,20β‐diOHprog but testosterone was without effect, suggesting that DOC has a direct action on the oocyte while testosterone probably acts at the level of the follicle. Estradiol‐17β had no effect on GVBD in response to SG‐G100 or 17α,20β‐diOHprog.

The action of SG‐G100 was shown to be dependent on the synthesis of a second Δ4 steroidal mediator of maturation since cyanoketone, a specific inhibitor of 3β‐hydroxy‐Δ5‐steroid dehydrogenase, completely abolished the maturational effects of the gonadotropin and pregnenolone but not Δ4 steroids. Radioimmunoassay of media in which oocytes were induced to mature in vitro with SG‐G100 revealed significantly elevated levels of progesterone and 17α,20β‐diOHprog. Estradiol‐17β levels, high in control media, were only elevated twofold by SG‐G100. Levels of the two progestogens were extremely low or nondetectable in media in which oocytes were incubated with cyanoketone, while estradiol‐17β levels remained high. These results are discussed in relation to other evidence indicating that 17α,20β‐diOHprog is the naturally occurring maturation‐inducing steroid of amago salmon. The role of other steroid hormones, particularly the possible involvement of corticosteroids, in the control of final oocyte maturation in teleosts is explored.
Two examples of monoamniotic monozygotic twinning in diploid parthenogenetic mouse embryos
Authors: Kaufman Matthew H.
Published: June 2005

In experiments in which diploid parthenogenetic mouse embryos cultured entirely in vitro from the one‐cell stage to the blastocyst were transferred to suitable recipients and maintained in “delay” for about 3 days before implanting. about 25–40% subsequently developed to somite‐containing stages. In all, over 30 such embryos were examined. Most were morphologically normal, and equivalent to fertilized development observed on the 9th–11th days of pregnancy. A few embryos, however, had neural tube abnormalities, but of greatest interest were two sets of monoamniotic monozygotic twins. It is unclear whether the twins in some way resulted from the parthenogenetic condition, or from the “delayed” state. The present examples are discussed in the context of previous observations of monozygotic twinning in the mouse and man.
Oscillatory activity of maturation promoting factor (MPF) in extracts of Rana pipiens eggs
Authors: Masui Yoshio
Published: June 2005

Dejellied Rana pipienseggs were crushed by centrifugation and clear extracts were prepared by further centrifugation at 150,000 × G for 2 h. The extracts were kept at 0°C for 2 to 3 weeks. At intervals during the storage period, 80‐nl aliquots were injected into ovarian oocytes to assay maturation promoting factor (MPF). In most cases, MPF activity disappeared from the extracts on day 3 or 4, but reappeared on the following days and persisted 2 or 3 days at high levels before disappearing again. The cycle of MPF activity in extracts was repeated fairly regularly a few times during storage of the extracts. The average period of the oscillation was 5.05 + 1.25 days. If a single extract was assayed by oocytes from different frogs, all the assays exhibited exactly the same patterns of changes in MPF activity during storage of the extract. This indicates that the oscillations in MPF activity observed during storage of the extracts reflect changes in MPF activity intrinsic to the extracts, rather than fluctuations in the sensitivity of recipient oocytes to MPF. The reappearance of MPF activity in stored extracts was sensitive to Ca and dependent on Mg ions. The MPF activity that recurred periodically in cold‐stored extracts was indistinguishable from that contained in fresh extracts, since oocytes induced to mature by the recurring MPF activity had chromosomes condensed to meiotic metaphase and were capable of cleavage when injected with a sperm suspension. The oscillatory behavior of MPF activity observed in this study may be comprehended on a conceptual basis by aid of a kinetic model.
In vitro ovulation of hamster oocytes depends on contraction of follicular smooth muscle cells
Authors: Talbot Prudence , Chacon R. S.
Published: June 2005

Smooth muscle cells (SMC) of the hamster follicle contract prior to ovulation, and their contraction produces a V‐shaped constriction in the base of the follicle. We have determined when basal constrictions first appear in follicles removed from females at various preovulatory times by examining stained, thick sections with a brightfield microscope. The time to ovulation was controlled by injecting the female with human chorionic gonadotropin (hCG). The shape of the follicle was classified as flat, small V, medium V, or large V depending on the size of the basal constriction. Twenty‐nine out of 30 follicles removed 12 hours after the hCG injection had flat bases or small V‐shaped constrictions. However, by 12.5 and 13.0 hours after hCG injection, 45 and 54%, respectively, of the follicles had medium and large V‐shaped constrictions in their bases. Transmission electron microscopy was used to confirm that flat follicles had uncontracted SMC, follicles with small V's had uncontracted or slightly contracted SMC, and follicles with medium and large V's had highly contracted SMC. When 12 hour follicles were removed from females and cultured in vitro, ovulation did not occur. Microscopic examinations showed that SMC had not contracted in these follicles during culture. Some (36.6%) 12.5 hour follicles and most (69.9%) 13 hour follicles ovulated when cultured in vitro. The majority of those which failed to do so, did not have contracted SMCs. We interpret these data to mean that in hamsters follicular SMC begin to contract in some follicles between 12–12.5 hours after the hCG injection. If contraction has begun in vivo, then the ovary may be removed from the female and ovulation will occur during in vitro culture. If contraction has not begun in vivo, it will not do so using the in vitro conditions described in this study and ovulation will not occur. These observations are consistent with the idea that the contraction of follicular SMC is necessary for hamster ovulation, and suggest that either stretch or neurotransmitters may initiate SMC contraction in vivo.
Neural crest ablation and limb morphogenesis
Authors: Shoobridge R. , Velkou D. , McCredie J.
Published: June 2005

Left caudal neural crest was ablated by diathermy in 2‐day‐old chick embryos, to injure the region of sensory sciatic innervation before the appearance of the hind‐limb bud. Embryos were fixed immediately, 24 hr and 14 days later, for examination of the effects of the ablation upon neural crest, neural tube, somitic mesoderm, and subsequent limb development. All embryos examined immediately and at 24 hr after ablation showed damage to the left neural crest, but the injury extended deeper into neural fold or tube, across the midline, and into somitic mesoderm. Of 17 chicks which survived to 16 days, 7 had gross deformity of the left leg and 10 had morphologically normal legs. Deformed chicks had a significant reduction in the mass of dorsal root ganglia on the operated side but no reduction in the area of the spinal cord. Operated chicks without limb deformities showed reduction of spinal cord but not of dorsal root ganglia. This suggests that limb morphogenesis may be quantitatively related to neural crest but not to neural tube. This possibility is considered in the light of previous publications. However, the experimental limitation of the diathermy method leaves the final conclusion open to interesting speculation and to future examination by improved experimental design.
Scaling of the brain and the eye cooling system in birds: A morphometric analysis of the Rete ophthalmicum
Authors: Midtgård Uffe
Published: June 2005

A morphometric analysis has been made of the rete ophthalmicum which is a functional arteriovenous heat exchange system in the heads of birds. The morphological data were obtained from histological sections of the rete from 40 species of birds covering a weight range of 20,000‐fold. The maximal number of retial arteries, the length, the diameter of the arteries, the total arterial cross‐sectional area, and the maximal exchange area have been expressed in terms of allometric equations. Other parameters important for the countercurrent heat exchange effect have been estimated or calculated. By use of simple physical laws for ideal heat exchangers, it is shown that the temperature decrease of the arterial blood passing the rete is rather constant over a wide range in body weight, but larger than previously reported body‐to‐brain temperature differences. The results are consistent with the heat exchange function of the rete and provide support for the idea that the rete, besides serving as a cooling system for the brain, also may be important in reducing heat loss from the eye.
Studies on factors affecting the timing of early morphogenetic events during starfish embryogenesis
Authors: Mita Izumi
Published: June 2005

Eggs of the starfish Asterina pectinifera were divided into two equal‐sized parts with fine glass needles after the first polar body formation, and nucleate halves were fertilized. Half embryos thus formed continued to divide and developed into morphologically normal, but dwarf bipinnariae. In order to explore possible mechanisms which determine the time of onset of early morphogenetic events, the timing of initiation of asynchronous cleavages, blastulation, and gastrulation was compared between half and whole embryos. The following results were obtained: (1) half eggs divided synchronously until the ninth cleavage, but the asynchronous cleavages started one division earlier in half embryos compared with whole embryos; (2) blastulation started at the 256‐cell stage in both half and whole embryos; (3) half embryos initiated gastrulation at almost the same time as did whole embryos; and (4) the average number of constituent cells of half gastrulae was about 2500, while that of normal gastrulae was about 4500. These results indicate that (a) the start of the asynchronous cleavages, is closely associated with the nucleocytoplasmic ratio, but not with the number of cell divisions; (b) the timing of blastulation is not affected by the altered nucleo‐cytoplasmic ratio; and (c) the timing of gastrulation is not determined by the number of cell divisions.
Neural differentiation in fly CNS transplants cultured in vivo
Authors: Nässel D. R. , Sivasubramanian P.
Published: June 2005

To study the influence of afferent retinal innervation on neuronal organization in the CNS during differentiation in the fly Sarcophaga bullata, we transplanted larval CNS with or without eye imaginal discs into freshly pupariated animals. After metamorphosis and eclosion of the adult flies, the transplants were recovered and analyzed histologically.

Optic lobes transplanted with eye disc differentiated fully like normal in situ optic lobes. In transplants without discs the outermost optic neuropil, the lamina, did not differentiate at all, and the more central ones, medulla, lobula, and lobula plate, were reduced in volume. Although certain neuron types present in normal optic lobes could be identified, the strict columnar and layered organization of these neuropils was no longer apparent in the eyeless transplants.

The experiments confirm the earlier notion that afferent innervation strongly influences normal differentiation in the peripheral optic lobes of insects, whereas more central neuropil regions are less dependent on the retinal innervation. In addition, we show that the formation of the normal pattern of dendritic arborizations as well as strict columns and layers in these lobes seems to require retinal and/or laminar input.
Keratin diversity in the reptilian epidermis
Authors: Wyld Jean A. , Brush Alan H.
Published: June 2005

The ϕ keratins extracted from individual turtles and snakes were compared. The extent and nature of the molecular differentiation associated with the production of structurally distinct epidermal tissues was determined. The electrophoretic comparisons, molecular weight, and chemical fractionation indicate that these tissues contain unique proportions of the constituent keratin monomers specific to each species. This pattern of differentiation is similar to that previously observed for avian scale, claw, and beak, and for mammalian horn and hoof. This suggests that several “scale‐like” structures with distinctive chemical properties may be produced by a single individual without the synthesis of wholly unique proteins. The implications of these observations for the evolution of mammalian hair and avian feathers are discussed.
Obligatory hibernation for completion of vitellogenesis in the lizard Lacerta vivipara J.
Authors: Gavaud Jacqueline
Published: June 2005

Hibernation in Lacerta vivipara from Massif Central (1,000–1,200 m) lasts 6–7 months and is immediately followed by vitellogenesis, gestation, and parturition within a short period of time (May–August). Suppression of hibernation by maintaining females in active life (food and high temperatures) inhibits the resumption of ovarian growth in spring: i.e., the reproductive system remains indefinitely refractory to high temperatures. In order for vitellogenesis to be completed, females need to hibernate below S–10°C with sufficient duration (“amount of cold” thresholds). The prolongation of the exposure of females to low temperature beyond the minimal stay gradually improves their ability to complete vitellogenesis: The number of females responding increases, and the heat requirement for the onset of ovarian growth decreases.
Limb regeneration to digit stages occurs in well‐fed adult newts after hypophysectomy
Authors: Tassava Roy A.
Published: June 2005

Experiments were designed to determine the maximum survival time and extent of limb regeneration of well‐fed adult newts (Notophthal‐mus viridescens) after complete hypophysectomy.

Adult newts were either well‐fed or fasted for 3 weeks at which time hypophysectomies were performed. Forelimbs were amputated 5 days posthypophy‐sectomy. Fasted hypophysectomized newts did not survive beyond 4 weeks, and limb regeneration was either absent or abortive. All of the well‐fed newts survived to 3 weeks posthypophysectomy, and even at 6 weeks posthypophy‐sectomy showed 30% survival. In the complete absence of the pituitary gland, many of the fed newts regenerated limbs to digit stages. It is concluded that pituitary hormones are not an absolute requirement for limb regeneration of adult newts. Newts in good nutritional condition at the time of hypophysectomy survive longer and their limbs regenerate to more advanced stages.
Spine regeneration in larvae of the crab, Rhithropanopeus harrisii
Authors: Freeman John A.
Published: June 2005

Dorsal spines were removed from intermolt first instar larvae of Rhithropanopeus harrisii. The wound was immediately closed by hemocytemediated clot formation. Epidermal cells from regions adjacent to the spine then formed a continuous, single‐cell‐thick layer beneath the clot. During premolt of the first instar, the distal cells formed a new spine tip by apical extensions. Regenerating spines underwent enhanced growth during the first two instars; this resulted in a normal‐sized spine by the third instar. Determination of cell density in regenerating spines indicated that the enhanced growth during reeneration was due to increased cell division during the first two instars. Spine regeneration had no effect on duration of the molt cycle, onset of premolt, or metamorphosis.
The common inhibitory innervation of the pereiopods of the crayfish Cherax destructor
Authors: Cooke Ian R. C. , MaCmillan David L.
Published: June 2005

Stimulation of either the medial or lateral giant axons in the crayfish (Cherax destructor; Decapoda: Astacura) CNS was found to activate the common inhibitor neuron reliably in each of the pereiopods. This property was used to study the extent of the common inhibitory innervation of the leg muscles, including the muscles of the coxa, basis, and ischium. The common inhibitor was found to innervate all of the muscles of the pereiopod.
Survival of mouse embryos frozen‐thawed slowly or rapidly in the presence of various cryoprotectants
Authors: Miyamoto Hajime , Ishibashi Takehiko
Published: June 2005

Eight‐cell mouse embryos were frozen by using glycerol, ethylene glycol, or erythritol as the cryoprotectant. The samples were slowly cooled (0.5°C/min) to temperatures between −10 and −79°C before direct transfer to liquid nitrogen (− 196°C) and thawed slowly (∼ 20°C/min) or rapidly (∼ 500°C/min). The highest survival rates of embryos in 1 and 2 M glycerol were obtained after transfer to −196°C from −40 to −79°C, regardless of the thawing rate (72 to 90%), except for those of embryos thawed slowly in 2 M glycerol, in which case highest survival rates were obtained after transfer from −70 and −79°C (78 to 82%). With slow thawing, survival of embryos in 1.2 M ethylene glycol reached maximal levels at transfer temperatures between −50 and −79°C (82 to 89%) and with rapid thawing at transfer temperatures between −40 and −79°C (84 to 90%). The highest survival rates of slowly thawed embryos in 0.6 M erythritol were obtained after transfer to −196°C from −35 and −40°C (53 to 55%) and of rapidly thawed embryos after transfer from −30°C (46%). These results show that the transfer temperatures to liquid nitrogen, at which the highest survival rates of mouse embryos are obtained, vary with the cryoprotectant and the thawing rate. It appears that with glycerol and ethylene glycol mouse embryos are less sensitive to the thawing rate when slowly cooled to lower subzero temperatures before rapid cooling.
Serotonin or its agonist 5‐methoxytryptamine can stimulate hamster sperm acrosome reactions in a more direct manner than catecholamines
Authors: Meizel Stanley , Turner Kenneth O.
Published: June 2005

Serotonin (50 μM) or its agonist 5‐methoxytryptamine (5 μM) stimulated the acrosome reactions of golden hamster sperm within 15 min after addition to sperm capacitated in vitro for 4.5 h. The stimulation was inhibited by the serotonin receptor antagonists quipazine or cyproheptadine. Epinephrine (70 μM), norepinephrine (50 μM), and dopamine (25 μM) were unable to stimulate acrosome reactions even at 30 min under the same conditions, even though previous studies had demonstrated stimulation by these catecholamines at the same concentrations when present from the start of the capacitation time course. Epinephrine (5 μM) also was unable to stimulate at 30 min. These results demonstrate that serotonin and its agonist have a more direct effect on the hamster sperm acrosome reaction than other biogenic amines and that the effect is receptor‐mediated.
Rhythmic contractions of the blastoderm of the medaka Oryzias latipes, a teleost
Authors: Fluck R. , Gunning R. , Pellegrino J. , Barron T. , Panitch D.
Published: June 2005

The blastoderm of the medaka embryo contracts rhythmically during epiboly; the time for a contractile wave to move over the entire blastoderm is about one minute at 25°C. The primary objective of this study was to determine which layer(s) of the blastoderm participate in these contractions. We watched changes in the shape of wounds in the enveloping layer (a simple epithelium that covers the blastoderm), contractions of embryos in which the segmentation cavity had been inflated with saline media, and the movement of embryos from which the enveloping layer had been surgically removed. We conclude that both the enveloping layer and the underlying yolk syncytial layer participate in the contractions. The contractions were inhibited by cytochalasin B (5 or 10 μg/ml), by introducing 100 mM K+ into the segmentation cavity, and by bubbling carbon dioxide through the bathing medium. Elevating the [K+] in the external medium had no apparent effect on the contraction nor did adding the cholinergic antagonists, atropine and d‐tubocurarine, to either the bathing medium or the segmentation cavity. We conclude that microfilaments are involved in the contractions, and we discuss the possibilities that changes in the membrane potential of the cells may precede or accompany the contractions and that the contractile waves may be preceded by signals propagated through gap junctions. We conclude, furthermore, that acetylcholine has no role in either the initiation or the propagation of the contractile waves. An improved method for dechorionating medaka embryos, based on previously published protocols, is described. With this method, embryos can be dechorionated in 3 hours and can be obtained as young as blastulae.
Assessment of mutagenic damage following ethyl methanesulfonate mutagenesis in the axolotl (Ambystoma mexicanum)
Authors: Armstrong John B. , Fletcher William S.
Published: June 2005

When male axolots (Ambystoma mexicanum) were treated with 100 mg/liter of ethyl methanesulfonate (EMS), a dominant lethal effect was obtained. Embryonic survival of Fl progeny was most severely reduced between about 50 and 150 days after treatment. Dominant lethal lesions probably consist of chromosome breaks that lead to loss of parts of chromosomes or entire chromosomes. The appearance of embryos with a single nucleolus was used to assess this type of damage. The peak incidence of such embryos coincided with the peak of dominant lethality. At 25 mg/liter EMS, there was no significant dominant lethal effect, but as many as one‐fourth of the embryos appeared morphologically abnormal during the period between 50 and 120 days after treatment. A small but significant number of embryos with a single nucleolus were also obtained.

To assess possible recessive lethal damage, androgenetic haploids were produced from some of the mutagenized males. A broad trough of reduced haploid survival was obtained at 100 mg/liter, suggesting that damage is produced in most or all spermatogenic stages. At 10 mg/liter, where there was no dominant lethal effect or significant incidence of embryos with a single nucleolus, a broad period of reduced haploid survival was also obtained. Though we cannot exclude the possibility that chromosome abnormalities contribute to the reduced haploid survival, even at this low dose, the type of damage being assessed is almost certainly less severe than that leading to dominant lethality.
Annual cycle of body size and blood parameters of the aquatic adult red‐spotted newt, Notophthalmus viridescens
Authors: Pitkin Ruthanne Batcheller
Published: June 2005

A minimum of 20 aquatic, adult Notophthalmus viridescens were captured approximately every other month during 1980 in order to investigate seasonal changes in body size and blood parameters. Hemoglobin concentration, hematocrit, mean cell hemoglobin, sex, weight, snout‐to‐tail length, snout‐to‐vent length, and the presence of trypanosomes on blood smears were determined. Environmental variables measured included temperature (range 5–26°C), oxygen concentration (range 5.7–12.2 mg/L), and pH (range 6.5–7.5) of water at the pond's edge. Three anemic specimens (< 0.03 gHb/100 ml blood) were found. The only significant (P < 0.05) seasonal effects were that the mean hematocrit of the July sample was greater than that of the March sample and the incidence of trypanosome infection of the March collected newts was lower than those collected in May, July, and August. Significant (P < 0.01) linear relationships were found within the body size and blood parameters but not between them. Females had significantly (P = 0.000) higher hematocrits than males. The hemoglobin concentration and hematocrit did not correlate with the assumed seasonal oxygen demands of the newt.
Glucose‐6‐Phosphate dehydrogenase isozymes in fish—a comparative study
Authors: Kidder Gerald M.
Published: June 2005

The electrophoretic distribution and substrate specificities of isozymes of glucose‐6‐phosphate dehydrogenase (E.C. 1.1.1.49) were studied in seven species of teleost fish. The fish examined included two species of bonefish, Albula neoguinaica and A. glossodonta (Albulidae, Anquilliformes) (Shaklee and Tamaru, '81), and five representatives of the order Perciformes: two species of but‐terflyfish, Chaetodon miliaris and C. aurega (Chaetodontidae); a goatfish, Upeneusarge (Mullidae); a goby, Bathygobius fuscus (Gobiidae); and a snapper, Pristipomoides filamentosus (Lutjanidae). After horizontal starch gel electrophoresis, gel slices were stained using a variety of substrates and cofactors. In all species except the goby, two groups of isozymes were distinguished, corresponding to the mammalian G6PD (specific for glucose‐6‐phosphate (G6P) and NADP+) and H6PD (capable of utilizing galactose‐6‐phosphate and in certain cases other monosaccharide phosphates in addition to G6P). None of the five visible isozymes in the goby was specific for G6P. In each of the other species a single G6P‐ and NADP + ‐specific isozyme was noted, having the most rapid mobility toward the anode. In addition, it was found that all of the isozymes in all of the fish examined could catalyze the oxidation of fructose‐6‐phosphate at a rate comparable to that for G6P, suggesting that glucose‐6‐phosphate dehydrogenase can obviate the role of glucosephosphate isomerase in monosaccharide metabolism.
Erythropoiesis in the developing rainbow trout, Salmo gairdneri irideus: histochemical and immunochemical detection of erythropoietic organs
Authors: Iuchi Ichiro , Yamamoto Masamichi
Published: June 2005

In the rainbow trout, Salmo gairdneri irideus, round, disc‐like erythrocytes in the embryonic circulation (Ery L) are replaced by small, elliptical, disc‐like erythrocytes (Ery ImA) after hatching. In the peripheral blood of alevins, Ery ImAs grow into mature, adult erythrocytes (Ery A) of large elliptical, disc‐like shape (Iuchi, '73b; Yamamoto and Iuchi, '75). Ery L and Ery A have larval and adult hemoglobins, respectively (Iuchi, '73a). The ontogenetic sequence of hemoglobin switching and erythrocyte replacement during erythropoiesis was examined by o‐dianisidine histochemistry as well as immunohistochemistry using FITC‐antibody probe specific to adult hemoglobins.

The first phase of embryonic erythropoiesis (for Ery L) occurs in the intraembryonic “intermediate cell mass” as well as the extraembryonic blood islands on the yolk sac. This phase of erythropoiesis is transient, continuing during the 7th to 12th day after fertilization and ceasing by the 15th day (5th day before hatching).

There is a mixed population of Ery L, ImA, and A in the peripheral blood of posthatching alevins. Ery ImA and A showed immunofluorescence with FITC anti‐Hb A antibody but Ery L did not. Erythroid cells, stainable with FITC anti‐Hb A antibody, were observed in the kidney and the spleen 1 day before hatching and thereafter, but not in the liver throughout all stages examined. Therefore, we conclude that new erythropoiesis (erythropoiesis for Ery ImA and Ery A) began in the kidney and the spleen 1 day before hatching. These findings indicate that hemoglobin switching during the ontogeny of rainbow trout is based on erythrocyte replacement, correlated with a shift in the site of erythropoiesis from one organ to another.
Release of calcium from bone in vitro by homogenates of embryonic chick parathyroid glands
Authors: Rosen Vicki , Clark Nancy B.
Published: June 2005

Parathyroid glands were removed from chick embryos of 12 to 20 days of development and tested for their ability to stimulate calcium release from calcium‐45‐labeled embryonic chick bone in organ culture. All glands stimulated calcium‐45 release to approximately the same degree, although the glands of 16‐ and 20‐day embryos had a somewhat enhanced calcium‐mobilizing ability. It appears that parathyroid hormone is present in the embryonic chick coincidental with the time of early development of the skeleton and is present in similar quanities throughout the remainder of embryogenesis.
Melanophores of Zacco temmincki (teleostei) are light sensitive
Authors: Iga Tetsuro , Takabatake Ikuo
Published: June 2005

The responses of melanophores of a cyprinid fish Zacco temmincki to changes in illumination were examined in isolated scale preparations of the adult fishes. Melanosomes in the melanophores aggregated in darkness and dispersed in light. These responses were invariably induced, even in denervated melanophores. These light responses, the dark‐induced aggregation and the light‐induced dispersion, were not affected by a number of alpha and beta adrenergic blocking agents. It was concluded that the melanophores of Zacco temmincki were themselves light sensitive and responded directly to light by melanosome translocations. The light responses were quantitatively assessed in relation to the intensity of illumination.
Changes in polyamine content during limb regeneration in adult Xenopus laevis
Authors: Kurabuchi Shingo , Matsuzaki Shigeru , Inoue Sakae
Published: June 2005

Polyamine contents in the regenerates were determined at various stages after amputation of the forelimbs of the adult female Xenopus laevis. Putrescine, spermidine, spermine, and sym‐homospermidine were detected in all the specimens examined. Cadaverine was detected only in a limited number of samples. At 5 days after amputation of forelimbs, well before the formation of regenerates, the putrescine content in the stump tissues increased, followed by the increase in spermidine content.

The putrescine level in the forelimb regenerates was highest between 30 and 50 days after amputation, and then decreased. The spermidine concentration in the regenerates was about 20 times greater than that in intact forelimbs all throughout the experiments. The concentration of spermine was initially lower than that of both putrescine and spermidine and further decreased soon after amputation. The concentration of sym‐homospermidine was originally very low and increased slightly during regeneration. The significance of these results, with respect to the function of polyamines in forelimb regeneration of Xenopus laevis, is discussed.
The relationship among ovarian condition, steroid hormones, and estrous behavior in Anolis carolinensis
Authors: Jones Richard E. , Guillette Louis J. , Summers Cliff H. , Tokarz Richard R. , Crews David
Published: June 2005

The lizard Anolis carolinensis ovulates a single egg alternately from each ovary every 14 days. The ovulated egg enters the ipsilateral oviduct, acquires a shell, and is oviposited 18 or 19 days later. Thus, there is only a single egg in one of the oviducts (one‐egg condition) during most of the estrous cycle, but there is a 4–5‐day period when a mature, shelled egg is in one oviduct while a recently ovulated egg is in the contralateral oviduct (two‐egg condition). Analysis of ovarian follicular diameters indicates that the largest follicle in a single ovary exhibits a growth spurt about halfway through its 28‐day vitellogenic growth phase. The corpus luteum, once formed from the ovulated follicle, exhibits a linear decrease in weight, becoming fully regressed just before oviposition of the egg in the ipsilateral oviduct. Plasma concentrations of estradiol‐17β and progesterone are high in two‐egg animals. After oviposition, plasma concentrations of progesterone are still high in one‐egg animals whereas those of estradiol‐17β are much lower. These ovarian and hormonal changes during the estrous cycle are discussed in relation to the probable sources of estradiol‐17β and progesterone, the control of the alternating pattern of ovulation and oviposition, and the role of steroid hormones in female sexual receptivity in this species.
Acetylcholinesterase activity in embryonic and larval development of Artemia salina leach (crustacea phyllopoda)
Authors: Raineri M. , Falugi C.
Published: June 2005

Acetylcholinesterase (AChE) activity has been studied in Artemia salina embryos and larvae by quantitative, histochemical, and electrophoretic methods. An AChE activity is present in dehydrated encysted gastrulae and remains low in rehydrated developing embryos, showing at hatching an increase that becomes faster during the nauplius stages (twice the gastrula activity at the nauplius II stage), and continues linearly in the first metanauplius stages. The histochemical staining, faint and diffuse in dehydrated gastrulae, in more advanced embryos becomes localized in cell membranes and stronger in differentiating tissues; most AChE activity is localized in the nervous and muscular cells, and a fainter one in the differentiating metanauplius segments. Dehydrated cysts show one electrophoretic AChE band, that is no longer detectable in rehydrated embryos and larvae, while two other bands appear, that migrate more slowly; in advanced larval stages, the more cathodic band is predominant. In dehydrated cysts, isoelectric focusing separates three AChE bands with isoelectric points (IP) at pH 5.0, 5.7, and 5.9; in hydrated embryos and larvae, the band at pH 5.0 is absent and another is seen at pH 5.5. Eserine, DFP, and BW284c51 inhibit the enzyme activity strongly and cause paralysis of larvae; also tubocurarine blocks the motility. These results are discussed in relation to the differentiation of the neuromuscular system and to the development of motility. As a hypothesis, in early embryonic stages, before any neuromuscular differentiation is evident, a cholinergic‐like system might regulate non‐neural cell activities and interactions, associated with embryogenetic events.
The time course of seawater acclimation in Fundulus heteroclitus L.
Authors: Jacob William F. , Taylor Malcolm H.
Published: June 2005

Serum Na+ and osmolality increased significantly within 12–24 hours after transfer of Fundulus heteroclitus to seawater (SW) but returned to freshwater (FW) levels after 4 days in SW. Na+K+‐adenosine triphosphatase (ATPase) remained low during the first 2 days in SW but increased to a level characteristic of fully acclimated fish within 4 days. Serum cortisol did not display a marked elevation during the rise in Na+K+‐ATPase. Thus, the pattern of SW‐acclimation in F. heteroclitus is similar to that of the eel (Anguilla rostrata), but acclimation is accomplished somewhat more rapidly in F. heteroclitus and the prolonged period of elevated serum cortisol observed in the eel does not occur.

A distinct peak in cortisol was observed during acclimation to FW when gill Na+K+‐ATPase and serum osmolality were declining. This indicates that elevated serum cortisol does not always lead to an increase in Na+K+‐ATPase activity.
Regulation of the tricarboxylic acid cycle in sea urchin eggs and embryos
Authors: Mita Masatoshi , Yasumasu Ikuo
Published: June 2005

Contents of the tricarboxylic acid (TCA) cycle intermediates, coenzyme A (CoA) derivatives, and carnitine derivatives were estimated in the developing eggs and embryos of the sea urchin, Anthocidaris crassispina. Levels of the TCA cycle intermediates in unfertilized eggs were similar. The level of malate increased remarkably after fertilization and reached a plateau just before hatching out. Slight elevation in the level of citrate was also observed during early development. These suggest that metabolism of citrate and malate is altered during development. Long‐chain fatty acyl‐CoA was accumulated in unfertilized eggs. Its level decreased after fertilization, then gradually increased until the late gastrula stage and turned to decline. Free CoA level increased after fertilization and reached a peak around the gastrula stage, and thereafter it decreased, while short‐chain acyl‐CoA level decreased gradually after fertilization. Crude citrate synthase from sea urchin unfertilized and fertilized eggs was inhibited by palmitoyl‐CoA, though malate dehydrogenase was not inhibited. The palmitoyl‐CoA‐caused inhibition of citrate synthase was also relieved by spermine and spermidine. In view of the inhibition of citrate synthase by palmitoyl‐CoA at concentrations in unfertilized eggs, the enzyme is probably inhibited in unfertilized eggs by long‐chain acyl‐CoA and released from the inhibited state by the decrease in the level of long‐chain acyl‐CoA and the increase in the level of polyamines following fertilization.
The role of the yolk syncytial layer in determination of the plane of bilateral symmetry in the rainbow trout, Salmo gairdneri Richardson
Authors: Long Wilbur L.
Published: June 2005

Two types of morphogenetic cell movements are required for construction of a teleost embryo from the blastodisc. These are epiboly and convergence. Convergence is responsible for building the embryonic shield, thereby converting the radially symmetrical blastodisc to a bilaterally symmetrical one. Control of the convergence movement in rainbow trout, Salmo gairdneri, blastodiscs was investigated by marking the plane of bilateral symmetry with chalk. The blastodiscs were removed from their underlying yolk syncytial layers (YSL) and younger, radially symmetrical, blastodiscs were used to replace them. The newly transplanted blastodiscs formed planes of bilateral symmetry which matched the marked YSL substratum. Therefore, the YSL from an older, bilaterally symmetrical egg can impart its bilateral symmetry to a young, radially symmetrical blastodisc. This ability suggests that the YSL has the role of directing the cell movements which establish the embryonic shield during normal morphogenesis.
The relationship between the presence of cysteine lyase in the yolk sac endoderm and the disposition of the area vasculosa in the chicken blastoderm
Authors: Vanroelen Ch. , Vakaet L.
Published: June 2005

Two series of experiments were carried out to test the possible relationship between the presence of cysteine lyase and area vasculosa in the chicken blastoderm. In the first series, the localization of cysteine lyase was compared with the disposition of the area vasculosa at the successive stages of gastrulation and neurulation. In definitive streak stage chicken blastoderms, the enzyme first appeared laterally at the area pellucida–area opaca border. At older stages, this positivity extended rostrally and only finally did it appear in the caudal area. Based on these in toto observations, the relationship with area vasculosa, the distribution of which has been studied by Settle ('54), seems only incidental. In the second series, intermediate streak stage blastoderms were transversely dissected so that the rostral part did not contain any mesodermal component. The presence of cysteine lyase in this rostral part after 15 hr of culture suggests that the appearance of cysteine lyase in the yolk sac endoderm is not dependent upon the presence of area vasculosa. Moreover, the results suggest that the yolk sac endoderm of the chicken blastoderm is determined to produce cysteine lyase from the intermediate streak stage on.