bluuebunny/crossref_metadata_2025 huggingface dataset:
Thyroid and gonadal hormones in feather regeneration of the redheaded bunting, Emberiza bruniceps
Authors: Pati Atanu Kumar , Pathak Vishnu Kant
Published: June 2005

The time lag in the appearance of the first feather papillae (rate of feather regeneration) was studied after monthly depluming of the redheaded bunting (Emberiza bruniceps). Results indicate that the rate of feather regeneration varies over an annual time scale. When a comparison was made between monthly changes in levels of plasma thyroid hormones (thyroxine‐T4 and triiodothyronine‐T3) in redheaded buntings (Pathak and Chandola, '82a) and the rate of feather regeneration, the rate of regeneration showed a distinct correlation with levels of circulating T4. The rate of feather regeneration was faster during December and June when endogenous T4 levels were high and slower during July/August and March/April when levels of circulating T4 were relatively low. Such a relationship was, however, not observed with T3. Results of administration of T4 and T3 separately, in normal as well as in thyroidectomized birds; in different doses; and during different phases of the annual cycle, indicate a strikingly greater influence of T4 on the rate of feather regeneration and on the number of regenerated papillae than T3. Injection of propylthiouracil (PTU—an effective inhibitor of peripheral conversion of T4 to T3 in the redheaded bunting) in thyroidectomized birds that were also receiving T4, resulted in even faster rates of feather regeneration. Thyroidectomized birds receiving saline had no feather regeneration. Castration led to a slow rate of feather regeneration during May/June only. During this period thyroid activity of the redheaded bunting is known to be significantly influenced by gonadal hormones; this influence is not apparent during January/February or August. Injections of testosterone neutralized the effects of castration. It is concluded that T4 is more important than T3 for feather regeneration in redheaded buntings and that the effects of castration are due to alterations in thyroid function.
CNPase activity in the vertebrate retina, retinal pigmented epithelium, and choroid
Authors: Heath Ashley R. , Hindman Heather M.
Published: June 2005

The activity of the enzyme 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase (CNPase, E.C.3.1.4.37) has been studied in the retina of three vertebrate species. Activity was highest in the goldfish, followed by Xenopus laevis and Rana pipiens. Also, high activity levels were found in goldfish retinal pigment epithelium and choroid, but not in the other two species. When added to in vitro culture systems, 2′,3′‐cyclic nucleotides were found to have no effect on goldfish cone retinomotor movement, but caused a marked inhibition of Rana pipiens rod outer segment disc membrane shedding. It is suggested that CNPase may play a role in cellular processes requiring membrane structural reorganization.
Regional specificity of anuran larval skin during metamorphosis: Transdifferentiation of tadpole tail‐epidermis
Authors: Kinoshita Tsutomu , Sasaki Fumie , Watanabe Kyozo
Published: June 2005

During metamorphosis of the anuran tadpole, dorsal skin of the larva develops into adult back‐skin, whereas tail‐skin disappears simultaneously with resorption of the tail. Although it has been shown by transplantation experiments that the regional specificity is intrinsically determined in the respective skin, survival of a tail‐skin graft to the body has also been reported. In order to resolve the contradiction, developmental changes of back‐and tail‐skin grafts transplanted to the same tadpole were examined using an electron microscope. Back‐skin transplanted to the tail developed into adult‐type back‐skin, regardless of degeneration of the surrounding tail tissue. When tail‐skin was transplanted to the back region, collagen layers of the dermis degenerated during the early stage of metamorphosis. As metamorphosis progressed, however, fibroblasts derived from the adjacent back region formed collagen fibers in the subepidermis and the new dermis slowly replaced the regressive graft dermis. Epidermis of this tail‐skin graft remained intact, transforming into flattened epithelium and some epidermal cells clearly proliferated during metamorphosis. Furthermore, the epidermis formed secretory glands that are characteristic of adult back‐skin and survived even after metamorphosis. These results suggest that the tail‐epidermis is able to survive if the tissue is translocated under appropriate conditions prior to the beginning of tail resorption.
Selective sequestration of an oviductal fluid glycoprotein in the perivitelline space of mouse oocytes and embryos
Authors: Kapur Raj P. , Johnson Lincoln V.
Published: June 2005

Previously, we identified a 215 kd glycoprotein, GP215, which is associated with postovulatory oocytes and embryos, but not with preovulatory oocytes (Kapur and Johnson, '85). In this paper a polyclonal antibody that specifically recognizes GP215 has been used to study the distribution of the molecule in association with ova and preimplantation embryos and in the female reproductive tract. GP215 is present in epithelial cells lining the cranial portions of the oviduct and in oviductal fluid, ovarian bursal fluid, and medium conditioned by oviductal tissue in vitro. Immunofluorescence assays of the ovum and early embryo show that GP215 is sequestered in the perivitelline space. Since preovulatory oocytes exposed to bursal fluid in vitro acquire GP215, we hypothesize that GP215 is synthesized and secreted by the oviductal epithelium and secondarily associates with the ovulated oocyte. Sequestration of GP215 within the perivitelline space is relatively specific since mouse serum albumin, a major constituent of oviductal fluid, and other high molecular weight proteins are not similarly retained. These observations indicate that the composition of the perivitelline space may be significantly different from the greater environment external to the zona pellucida such that fertilization and early development of mammalian ova potentially take place in a distinct perivitelline microenvironment.
Properties of muscle phosphorylase b from a hagfish, Paramyxine atami
Authors: Yonezawa Satoshi
Published: June 2005

Phosphorylase b was purified to homogeneity from the muscle of a hagfish (Paramyxine atami), as judged by electrophoretic and immunological criteria. The purified enzyme was partially but not fully activated by AMP, and its conversion into the a form resulted in a three‐fold increase in activity. The enzyme was stimulated by SO42−, and kinetic experiments showed that SO42− markedly increased the affinity of enzyme toward substrates: in the presence and absence of 0.35 M SO42−, the apparent Km values of hagfish phosphorylase b were 0.04 and 1.3% for glycogen, 8.7 and 66 mM for glucose 1‐phosphate, and 0.05 and 1.0 mM for AMP, respectively.

Electrophoretic and immunological data indicated that the hagfish possessed a single molecular form of phosphorylase, like the lamprey. Some immunological relatedness between the hagfish enzyme and the enzyme from lamprey or skate was demonstrated.
Enzymatic esterification of exogenous retinol and 3,4‐didehydroretinol in the retinal pigment epithelium
Authors: Tsin Andrew T. C.
Published: June 2005

The kinetics of esterification of exogenous retinol by cell membranes prepared from the crude homogenate of the frog retinal pigment epithelium was studied. The formation of retinyl palmitate from added retinol was directly assayed by high performance liquid chromatography (HPLC). A linear relationship was observed between the amount of protein (up to 2 mg) in the incubation medium and the amount of retinyl palmitate formed. At room temperature, this reaction took less than 2 hours to complete. By varying the substrate concentration in the incubation medium, the reciprocal of initial velocity of the reaction (nmol retinyl palmitate formed per hour) was plotted against the reciprocal of substrate concentration (nmol of retinol). This double‐reciprocal plot shows that the apparent Km of the reaction was 10 μM with an apparent Vmax of 9.1 nmol of retinyl palmitate per hour per mg protein. When this assay was repeated in the presence of 3,4‐didehydrortinol (20 μM), the kinetics of the reaction showed the pattern of that of a competitive inhibitor, suggesting that 3,4‐didehydroretinol competes with retinol for the same active site for esterification. The esterification of 3,4‐didehydroretinol resulted in the formation of 3,4‐didehydroretinyl palmitate, which was also measured by HPLC. The amount of 3,4‐didehydroretinyl palmitate formed by this reaction decreased in proportion to increased retinol concentration in the incubation mixture. This further confirms that a competition exists between the esterification of retinol and 3,4‐didehydroretinol by retinal pigment epithelium of the frog.
Observations on fissiparity and spontaneous regeneration in two strains of agamic planarians (Dugesia gonocephala and Dugesia tigrina)
Authors: Zaccanti Francesco , Farne' Patrizia
Published: June 2005

Cephalic age “E,” fission interval “I,” and the number of animals produced at any fission crisis “S” have been defined as characteristic parameters for the fission cycles in two strains of agamic planarians (Dugesia gonocephala and Dugesia tigrina). Variations of weight, total amount of DNA, and total amount of RNA during standard fissiparous cycles have been measured for the same strains. The following results have been obtained. 1) The cephalic age “E” influences fissiparous reproduction: in samples of D. gonocephala, using heads regenerated for 10 months or more, the number of animals produced at any fission crisis “S” increases; by contrast, the fission interval “I” decreases in samples of D. tigrina with heads regenerated for 3 month or more. 2) The fissiparous cycle may be divided into three periods, based upon variations in weight and the total amount of DNA; an increase of these quantities was observed during the middle period. 3) Two periods of accumulation of RNA were observed at approximately the middle and the end of the fissiparous cycle, respectively. The results have been interpreted according to a model that involves a negative cephalic control of fissiparity and a preliminary organisation of regenerative blastema during the last part of the fissiparity cycle.
Stages and rates of normal development in the holostean fish, Amia calva
Authors: Ballard William W.
Published: June 2005

Thirty‐one stages in the normal development of the “living fossil” bony fish, Amia calva, are morphologically defined so as to identify the length of time after fertilization. Experiments were conducted and their results recorded in a study of morphogenetic cell movements in early embryos of this species, as reported previously (Ballard, '84) and in a paper that follows this one in this volume. Rates of progress through these stages are charted at several fairly constant temperatures. External and internal cell displacements from late cleavage to early organogenesis are described from living material and serial sections. Apperarance and changes in organogenesis are also described from dissections of all later stages to the time of disappearance of the yolk and onset of feeding, and they are correlated with earlier published descriptions which were based on specimens inadequately defined by body length or time from fertilization or hatching.
Plasma prolactin, thyroxine, triiodothyronine, testosterone, and luteinizing hormone during a photoinduced reproductive cycle in mallard drakes
Authors: Sharp P. J. , Klandorf H. , McNeilly A. S.
Published: June 2005

The temporal relationships between plasma concentrations of prolactin, thyroxine (T4) and triiodothyronine (T3) were determined in a group of six wild mallard drakes during the development and maintenance of longday refractoriness after transfer from 6 h light: 18 h darkness (6L:18D) to 20L:4D for 24 weeks. As shown by changes in the plasma concentrations of luteinizing hormone (LH) and testosterone, the birds came into breeding condition and then became long‐day refractory within 5 weeks of photostimulation. Long‐day refractoriness was maintained for the remainder of the study. Plasma prolactin began to increase immediately after photostimulation, although not as fast as the increases in plasma LH and testosterone. The concentration of plasma T4 also increased after photostimulation but, as shown by decreased plasma LH and testosterone levels, only after the birds had become long‐day refractory. The development of long‐day refractoriness was thus directly correlated with an increased plasma prolactin and not with a change in plasma concentration of T4. Plasma T3 decreased after photostimulation but returned to prestimulation values as the birds became long‐day refactory and remained stable for the remainder of the study. Concentrations of plasma T4 and prolactin returned to baseline values after about 15 weeks photostimulation showing that the long‐term maintenance of long‐day refractoriness is not directly related to continuously high plasma concentrations of either hormone.
Effect of cytochalasin B and demecolcine on freeze–thaw survival of murine embryos in vitro
Authors: Prather R. S. , First N. L.
Published: June 2005

The effects of cytochalasin B (CB), a microfilament inhibitor, and demecolcine (DC), a microtubule inhibitor, on freeze‐thaw survival and culture survival of early cleavage stage mouse embryos, was evaluated. In the first experiment, eight‐cell mouse embryos were frozen in dimethylsulfoxide (DMSO) or DMSO + 0.1 μg/ml DC + 7.5 μg/ml CB. In the second experiment, eight‐cell embryos were dehydrated and cultured in the presence of either DMSO, DMSO + DC, DMSO + CB, or DMSO + DC + CB for 45 min prior to rehydration and culture to simulate the osmotic and chemical changes encountered during the dehydration and rehydration procedures, but without the consequences of freezing and thawing. In the third experiment, additional eight‐cell embryos were frozen in either DMSO, DMSO + DC, DMSO + CB, or DMSO + DC + CB. The survival of embryos frozen in DMSO (75%) was significantly higher (P < 0.01) than that of embryos frozen in DMSO + DC + CB (55%). No differences (P = 0.55) were observed after a 48‐hr culture period in the development of embryos dehydrated, cultured, and rehydrated but not frozen. Embryos frozen in the presence of both DC and CB had a lower (P = 0.06) survival rate (55%) than that of embryos frozen in the presence of DMSO, DC, or CB (˜ 70%). These results suggest that both microfilaments and microtubules have a role in maintaining the structural integrity of the plasma membrane during the freeze–thaw process and that the loss of either loss does not seem to be detrimental to survival, but the loss of both results in lower survival.
Forelimb regeneration in the postmetamorphic bullfrog: Stimulation by dimethyl sulfoxide and retinoic acid
Authors: Cecil Mark L. , Tassava Roy A.
Published: June 2005

To examine the effects of retinoic acid and dimethyl sulfoxide on regenerative ability of anuran amphibians, the left forelimbs of 60 postmetamorphic froglets of Rana catesbeiana (bullfrogs) were amputated through the distal zeugopodium. Fifteen of the froglets had their left forelimb stumps immersed in dimethyl sulfoxide (DMSO) for 3 minutes, once immediately after amputation and once on each of 5 subsequent days. Another 15 frogs had their left forelimb stumps immersed in a 0.01 M solution of retinoic acid dissolved in DMSO for the same period of time. The remaining 30 control froglets received no treatment to their forelimb stumps. The untreated group of froglets did not regenerate structures distal to the amputation surface, while all limbs in both treated groups produced regenerates by 120 days postamputation. Regenerates of limbs treated with both DMSO alone and DMSO combined with retionic acid, although hypomorphic, were composed of multiple cartilage elements, which in many cases (46.7%) were organized as patterns partially resembling the skeletal arrangement of a normal forelimb. All of these regenerates exhibited bundles of striated muscle. In addition, nearly half (46.7%) of the regenerates in the DMSO + retinoic acid group possessed two separate regenerate outgrowths. The results demonstrate that young bullfrogs (Rana catesbeiana) possess a latent epimorphic regenerative capability, which can be stimulated by topical application to the wound surface of DMSO alone or DMSO combined with retionic acid.
Adipose tissue of Drosophila melanogaster: VII. Distribution of nuclear DNA amounts along the anterior–posterior axis in the larval fat body
Authors: Butterworth F. M. , Rasch E. M.
Published: June 2005

The DNA content of fat body nuclei was measured cytophotometrically as a function of position along an anterior–posterior (A–P) axis of the tissue throughtout larval development. There was a dramatic 55‐fold increase in the average amount of DNA per nucleus during the first 3 days of this period, but there was no further increase during the final day. However, the rate of increase had regional specificity. The amount of DNA per nucleus correlated significantly with its position along the A–P axis of the tissue: nuclei in a posterior direction contain gradually increasing amounts of DNA. There was up to a seven‐fold difference between the smallest anterior and largest posterior nucleus. In addition, for three of the ages studied there was a subgradient in the posterior region with a slope that was considerably steeper than that of the overall tissue gradient. The tissue has three characteristic morphological regions, anterior, medial, and posterior, which can be recognized early in development and which are maintained throughout the larval period. The distribution of nuclear DNA classes determined for cells in each region for the final 2 days of larval life became fixed before the final day of development. The significance of the DNA gradient in terms of a protein storage gradient is discussed.
Hight concentrations of methemoglobin in five species of temperate marine teleosts
Authors: Graham Mark S. , Fletcher Garth L.
Published: June 2005

Blood samples from five species of marine teleosts were assayed for methemoglobin (metHb) levels during winter and summer acclimatization. There was at least 7% total hemoglobin in the met‐form in all species, and as high as 27% in one species, the Atlantic cod (Gadus morhua).

There was significant seasonal variation in metHb levels for three of the five species, the highest values occurring during the winter months; cunners (Tautogolabrus adspersus) 15.6% in winter and 10.1% in the summer, shorthorn sculpin (Myoxocephalus scorpius) 20.0% in the winter and 8.19% in the summer, longhorn sculpin (Myoxocephalus octodecemspinosus) 17.3–21.6% in the winter and 8.12% in the summer. The winter flounder (Pseudopleuronectes americanus) and the Atlantic cod maintained metHb concentrations constant throughout the year: 13% and 27%, respectively.

There does not appear to be any relationship between the activity of a fish and the level of metHb in its blood.
The ultrastructure and physiology of the tergotrochanteral depressor muscle of the housefly, Musca domestica
Authors: Schouest L. P. , Anderson M. , Miller T. A.
Published: June 2005

The gross morphology, ultrastructure, and the physiological properties of the tergotrochanteral depressor muscle (TTM) of the housefly are described. Under transmission and scanning electron microscopy, the TTM is a highly modified multinucleated tubular muscle of the synchronous class of insect muscle. Mitochondria appear few in number (5% of muscle volume) but there is an extensive sarcoplasmic reticulum (20% of muscle volume). Two types of neuromuscular junctions were observed, but these junctions are considered functionally similar. Three neurons innervate the muscle, and when the muscle is orthodromically stimulated, three well‐defined thresholds are observed. Under repeated stimulation, the TTM fatigues rapidly but recovers in a short time. The TTM has a long “length constant” of 132.1 μm, 7.3 μF/cm2 membrane capacity, and a specific resistance of 394 Ωcm2.

The tergotrochanteral or “jumping” muscle has a behaviorally unique function. It is used only in the jump response preparatory to flight. TTM development is believed to have coevolved with an associated giant neuron to optimize the escape behavior response (response time 2.5 msec) in the housefly. The muscle has become specialized and more massive to increase the jump response. The TTM appears to be adapted physiologically and ultrastructurally for fast response and short twitch duration times.
A possible mechanism of action of 17β‐estradiol in stimulation of fertilization in vitro
Authors: Sjöblom Peter , Lindahl Per Eric
Published: June 2005

The effects of 17β‐estradiol (E2) on sperm‐egg interactions in the mouse were investigated. It was shown that E2 induces adhesiveness of the sperm head, expressed as sperm‐sperm and sperm‐egg binding. Since the concentration dependence of this process was similar to that observed for stimulation of in vitro fertilization by E2, it is suggested that induction of adhesiveness or initiation of processes that cause adhesiveness of the sperm head are of biological significance as preparatory steps for fertilization. Finally, the content of E2 in mouse eggs was determined and found to be 0.2 pg/egg, equally distributed between the oocyte together with the zona pellucida and the follicular cells with their associated intercellular matrix. The intraovum concentration is estimated as 10−6 M.
The releasing action of calcium upon cyclic AMP‐dependent meiotic arrest in hamster oocytes
Authors: Racowsky Catherine
Published: June 2005

The effect of increasing cytoplasmic calcium on cyclic adenosine monophosphate (cAMP)‐dependent meiotic arrest (%GV where GV is germinal vesicle) in hamster oocytes was investigated. The hypotheses tested were that 1) calcium is required for the spontaneous maturation of hamster oocytes, 2) elevation of calcium in the oocyte‐cumulus complex can antagonize cAMP‐dependent meiotic arrest, and 3) the intraoocyte level of cAMP remains unchanged, but heterologous metabolic coupling decreases, concomitant with calcium‐stimulation of germinal vesicle breakdown (GVBD). Levels of cAMP were elevated by culturing cells in the presence of dibutyryl cAMP (dbcAMP), isobutylmethylxanthine (IBMX) or forskolin and intracellular levels of calcium were manipulated by altering the CaCl2 concentration in the medium and/or by utilizing EGTA or A23187. Intracellular cAMP was determined by RIA, functional metabolic coupling was assessed by determination of the fraction of radiolabeled uridine marker transferred from the cumulus mass to the fraction of radiolabeled uridine marker transferred from the cumulus mass to the oocyte, and meiotic stage was determined cytogenetically.

Compared with the proportion of oocytes that underwent meiotic maturation in control medium containing 1.53 mM CaCl2, that of cumulus‐free (denuded) oocytes was unaffected by culture in the absence of added CaCl2, while that of cumulus‐enclosed (intact) oocytes was significantly decreased (%GV = 59.5 ± 4.8 and 4.2 ± 0.9 in 0 and 1.53 mM CaCl2, respectively, P < 0.001, where GV is germinal vesicle). EGTA prevented, in a dose‐dependent manner, the spontaneous maturation of denuded oocytes that occurred in 0 mM CaCl2 (ID50 = 0.05 mM, where ID50 is the dose of EGTA that inhibited GVBD in 50% cultured oocytes). In contrast, compared with the control, less than 1 mM EGTA failed to increase the %GV of intact oocytes, although 5 mM EGTA significantly increased meiotic arrest. The %GVBD of oocytes cultured in medium containing 0 mM CaCl2 was dose‐dependent on A23187 for both intact oocytes (ID50 = 3.0 μM) and for denuded oocytes cultured in the presence of 0.5 mM EGTA (ID50 = 2.7 μM). Elevated extracellular calcium significantly antagonized dbcAMP‐maintained meiotic arrest in both types of oocyte and the %GV was significantly correlated with the pH of the medium [(r) = −0.78 and −0.60 for intact and denuded oocytes, respectively, P < 0.001 in both cases]. Both CaCl2 and A23187 induced dose‐dependent antagonistic effects on forskolin‐maintained meiotic arrest in intact oocytes but neither antagonism was accompanied by significant dose‐dependent decreases in either the intraoocyte content of cAMP or the extent of heterologous metabolic coupling. These data indicate that calcium plays a central regulatory role in meiotic resumption in hamster oocytes but that the action of this cation is not mediated by modulation of the level of cAMP within the oocyte.
Avian spermatozoa penetrate zona‐free hamster oocytes In vitro
Authors: Samour Jaime , Moore Harry D. , Smith Caroline A.
Published: June 2005

After collection from the cloaca of adult males, budgerigar spermatozoa were incubated in modified BWW medium at pH 8.3. By light microscopy, many spermatozoa (> 100 per oocyte) were seen to be bound to the oolemma, and a small proportion (1–2 spermatozoa) were judged to have undergone fusion and penetration of the vitellus, as indicated by complete decondensation of their chromatin. The latter finding was confirmed at the electron microscope level by the presence of sperm nucleus, midpiece and tail in egg cytoplasm. This finding is discussed in relation to events at fertilization in the different Phyla.
New function for the granular skin glands of the eastern long‐toed salamander, Ambystoma macrodactylum columbianum
Authors: Williams Thomas A. , Larsen John H.
Published: June 2005

While it has been accepted for over 50 years that salamanders use their tails for fat storage, no caudal adipose tissue was detected in the eastern long‐toed salamander, Ambystoma macrodactylum columbianum. We provide evidence to show that a proteinaceous material, sequestered in the epidermally derived caudal granular skin glands, is the storage product. An increase in the size of these glands, at the expense of fat deposits in the tail, is interpreted as a solution to a conflict between two of the tail's major functions: nutrient storage and predator deterrence. Loss of caudal lipid allows for larger granular glands. With more secretory product available for defense, the possibility of the salamander's surviving an encounter with a predator is apparently enhanced. Storing protein is energetically beneficial because salamander diets are primarily protein, and its has been demonstrated by previous investigators that converting protein to fat for storage is metabolically inefficient.
Protein synthesis involvement in regulating pituitary‐induced progesterone levels in ovarian follicles of Rana pipiens
Authors: Petrino Teresa R. , Schuetz Allen W.
Published: June 2005

Involvement of protein synthesis in frog pituitary hormogenate (FPH)‐induced progesterone production and/or accumulation in ovarian follicles was investigated. In amphibians, cycloheximide (C), an inhibitor of protein synthesis, inhibits progesterone and FPH‐induced germinal vesicle breakdown (GVBD). However, the site and mechanisms of action of cycloheximide within ovarian follicles have not been elucidated. Intrafollicular progesterone produced by FPH is considered to mediate oocyte maturation; thus, cycloheximide may interfere with production and/or action of progesterone. Simultaneous treatment of FPH‐stimulated follicles with cycloheximide inhibited FPH‐induced progesterone accumulation (measured by RIA) and the accompanying‐GVBD in a dose‐dependent fashion. Inhibitory effects of cycloheximide on either FPH‐induced progesterone production or GBVD were not reversed when follicles were washed and returned to fresh medium devoid of FPH and cycloheximide. However, subsequent restimulation of washed follicles with FPH resulted in increased progesterone levels and oocyte maturation. The extent of reversibility, in terms of GVBD and progesterone production, after FPH restimulation varied between animals. Pretreatment of follicles with cycloheximide for 6 hours, without FPH, had little or no effect on progesterone production when follicles were washed and treated with FPH. Delayed addition of cycloheximide to follicles following FPH stimulation blocked further progesterone accumulation as indicated by measurement of intrafollicular progesterone at the time of cycloheximide addition and at the end of the incubation period. The results indicate that cycloheximide rapidly inhibits progesterone production and that continuous protein synthesis is required for progesterone accumulation. Furthermore, protein synthesis does not appear to be required for progesterone metabolism since intrafollicular progesterone declined with prolonged culture even in the presence of cycloheximide. The nature of protein(s) involved in follicular progesterone production remains to be elucidated. FPH mediation of oocyte maturation within ovarian follicles appears to depend upon protein synthesis in somatic follicle cells, which is required for progesterone production, and in the oocyte, to mediate the response to the steroid trigger.
An analysis of the influence of thyroid hormone on the synthesis of proteins in the tail fin of bullfrog tadpoles
Authors: Ray L. Bryan , Dent James Norman
Published: June 2005

By incubation of explants of tail fin from tadpoles of Rana catesbeiana in a solution of 35S‐methionine for 4 h, newly synthesized proteins were labeled isotopically. After separation by two‐dimensional polyacrylamide gel electrophoresis, those proteins were visualized by fluorography. Exposure of explants to culture medium containing thyroxine (T4) (150 nM) increased the incorporation of 35S‐methionine into several proteins with 48 h. Effects of T4 on the relative abundance of two of these newly synthesized proteins were detected after 8 h of hormonal treatment. Very similar patterns of newly synthesized proteins were observed when proteins from explants of tail fin removed from tadpoles at metamorphic climax and immediately incubated with 35S‐methionine were compared with proteins produced in fin derived from premetamorphic animals. These results are interpreted to indicate that both treatment of explants with T4 and elevation of endogenous levels of thyroid hormones during spontaneous metamorphosis increased the relative rates of synthesis of several identical proteins. The potential involvement of those proteins in early phases of metamorphic action which eventually lead to cell death and resorption is discussed.
An ovary‐stimulating factor in the shrimp, Paratya compressa
Authors: Takayanagi Hiroshi , Yamamoto Yoshihiro , Takeda Naokuni
Published: June 2005

The present study examined in vivo and in vitro the effects of extracts of the central nervous system (brain and thoracic ganglion) and muscle tissue on ovarian development in the shrimp, Paratya compressa. Both the brain and thoracic ganglion extracts stimulated vitellogenesis in oocytes. In particular, the brain extracts especially were more effective than those of thoracic ganglion in inducing this response. The extracts of muscle tissue did not have any effect on the ovaries. These results demonstrate that an ovarystimulating factor in the central nervous system may act directly in ovarian vitellogenesis.
Hypocalcemic effects of bovine parathyroid hormone (1–34) and stannius corpuscle homogenates in teleost fish adapted to low‐calcium water
Authors: Bonga S. E. Wendelaar , Pang R. K. , Pang P. K. T.
Published: June 2005

Injections of bovine parathyroid hormone (PTH 1–34) and homogenates of corpuscles of Stannius produce hypocalcemia in male killifish and tilapia adapted to calcium‐deficient seawater or fresh water, respectively. In fish from water with normal calcium concentrations no effects are noticeable. These results suggest similarity in bioactivity between PTH, the hypercalcemic hormone of terrestrial vertebrates, and the hypocalcemic factor of the corpuscles of Stannius in teleost fish.
Regulation of motility in sperm of the red‐spotted newt
Authors: Hardy Matthew P. , Dent James Norman
Published: June 2005

The motility of sperm was examined in vivo in the vas deferens, the spermatophore, and the spermatheca of the red‐spotted newt and in in vitro preparations with variations in osmolality, hydrogen ion concentration, and concentrations of specific osmolytes. Sperm were motile within the spermatophore, but little or no evidence of motility was seen in the spermatheca or the vas deferens. Approximately 25% of sperm from the vas deferens became motile when dispersed in spermatic fluid plasma, the sperm‐bearing liquid of the vas deferens, indicating crowding to be a possible motion‐restraining factor. Fewer than 50% were motile in several saline media isosmotic with spermatic fluid plasma, whereas more than 90% became motile in distilled water or media at osmolalities near that of pond water. Motility in isosmotic solutions persisted beyond 12 hours, but at low osmolality ceased by 6 hours. When dispersed at higher osmolalities initial motility was low but increased to isosmotic levels by 12 hours. Responses to immersion in solutions of mannitol were similar to ones observed in saline solutions of equivalent osmolality. Dispersion in hydrogen ion concentrations between pH 4 and 9 did not affect the initial motility of sperm, but after 12 hours at pH 9, pH 4 or 5 movement was inhibited. In general, these data indicate a major role for osmolality in the enforced quiescence of sperm during storage and demonstrate that the low osmolality of pond water is primarily responsible for the activation of sperm in the spermatophore of the newt.
Pressure‐adaptive differences in proteolytic inactivation of M4‐lactate dehydrogenase homologues from marine fishes
Authors: Hennessey John P. , Siebenaller Joseph F.
Published: June 2005

The inactivation by hydrostatic pressure of muscle‐type lactate dehydrogenase (M4‐LDH, EC 1.1.1.27; L‐lactate: NAD+ oxidoreductase) homologues from five shallow‐living and six deep‐living marine teleost fishes was compared. The pressures which inactivate these enzymes are much higher than the pressures experienced by any of the species. To determine whether hydrostatic pressure effects on protein aggregation state and conformation might influence proteolysis, the inactivation of LDH by the proteases, trypsin (EC 3.4.21.4) and subtilisin (EC 3.4.4.16) was determined at atmospheric pressure and 1,000 atm pressure. At 10°C and atmospheric pressure, the enzymes of the shallow‐living fishes are inactivated four times faster by trypsin and three times faster by subtilisin than are the homologues of the deep‐living species. At 1,000 atm pressure, the homologues of shallow‐occurring fishes were inactivated 28 to 64% more than predicted from the summed effects of denaturation by 1,000 atm pressure and tryptic inactivation at atmospheric pressure. In contrast, the homologues of the deep‐sea species were inactivated by trypsin 0 to 21% more than expected. At 1,000 atm, inactivation by subtilisin increased to a similar degree for enzymes from both deep‐ and shallow‐living species. However, at 1,000 atm, the M4‐LDH homologues of the deep‐sea species lost less activity (55.3%) than did the homologues of the shallow species (86.4%). In comparisons made at 200 atm, a pressure typical of the habitat of the deep‐occurring species, tryptic inactivation of the LDH of the shallow‐living Sebastes melanops was increased 14%. No pressure inactivation of the enzyme is evident at 200 atm. Two hundred atm pressure does not increase the tryptic inactivation of the enzymes of the two deep‐living macrourids. Increased structural stability of the enzymes of deep‐sea species may be an adaptation which prevents too rapid protein turnover, which would be energetically costly in the food‐poor deep sea.
Innervation pattern and responsiveness of melanophores in tail fins of teleosts
Authors: Miyata Seiji , Yamada Koji
Published: June 2005

The pattern of adrenergic innervation to melanophores in split tail fins of the goby, Tridentiger obscurus, and the guppy, Lebistes reticulatus, was investigated using 3H‐norepinephrine (3H‐NE) by light microscopic autoradiography. In goby fins, comparatively thick nerve bundles labeled with 3H‐NE ran approximately parallel to fin rays. Thin varicose fibers which branched out from the thick bundles formed rough plexuses around individual melanophores. In guppy fins, no thick nerve bundles could be observed, but numerous thin varicose fibers ran between fin rays, forming dense nerve plexuses on individual melanophores. In setioned preparations of guppy fins, the 3H‐labeled neural elements were observed to be in close contact with both surfaces of the cells (i.e., those facing the epithelial cell layer and the split side of fins), while in goby fins, the neural elements could be found only on the epithelial surface of the cells. Usually, melanophores in freshly isolated guppy fins responded with a full aggregation of pigment to isotonic KCl and maintained the state during the repetitive administration of the medium. Meanwhile, the degree of pigment‐aggregation response of goby melanophores to isotonic KCl decreased considerably during the treatment. The difference in the mode of melanophore response to K+ between two fish species was considered to be due to the difference in the density of neural elements around each melanophore and, probably as a consequence, in the amount of released neurotransmiter which acts on the cells.
Autonomous fluorescence of eggs of the ascidian Ciona intestinalis
Authors: Deno Takuya
Published: June 2005

Under ultraviolet illumination, eggs of the ascidians Ciona intestinalis and C. savignyi were found to emit specific autonomous fluorescence in the myoplasmic region of egg cytoplasm, the vacuoles of test cells, and the follicular vesicles of follicle cells. The fluroescent egg cytoplasm formed a crescent after ooplasmic segregation and was distributed mainly to presumptive muscle cells. The fluorescence of the test cells appeared at early stages of oogenesis and remained constant during oogenesis and embryogenesis. The number of test cells within the perivitelline space of Ciona unfertilized eggs was estimated to be 1,154 ± 182 (S.D.); at the tailbud stage the number was 1,089 ± 149 (S.D.). These counts suggest that there is no proliferation of test cells from fertilization to at least the tailbud stage. The fluorescence of follicle cells also appeared at early stages of oogenesis and did not change during embryogenesis. The number of follicle cells attached to the chorions of eggs was estimated to be 63 ± 8 (S.D.).
Pregnancy‐associated esterase in sera of baboons
Authors: Cheng M.‐L. , Kuehl T. J. , Vandeberg J. L.
Published: June 2005

Baboon serum samples were resolved by starch gel electrophoresis and polyacrylamide gradient gel electrophoresis and stained with naphthol substrates for esterase activity. An esterase that hydrolyzed α‐naphtyl butyrate in preference to α‐naphthyl acetate was found in very high activities in some individuals but not others. It migrated just cathodal of the albumin band in starch gels. In polyacrylamide gradient gels, it co‐migrated with albumin and had an apparent molecular weight of approximately 65,000 daltons. Electrophoretic analysis by gel electrophoresis of random serum samples from male and female baboons indicated that this esterase was present only in the sera of pregnant baboons. Further investigation of serial samples collected from carefully monitored baboons confirmed that the amount of activity of this esterase was correlated with stage of pregnancy. Therefore, it was named pregnancy esterase (PE). PE was detectable by gel electrophoresis and chromogenic staining techniques as early as day 30 of pregnancy; its activity gradually increased with progressive pregnancy and reached maximum activity near full term (182 days). Soon after parturition, the activity of PE decreased rapidly and was not detected in maternal sera by day 14 postpartum. No evidence of PE was detected in sera of pregnant humans.
Gill morphology and sodium influx in the rainbow trout (Salmo gairdneri) acclimated to artificial freshwater environments
Authors: Avella Martine , Masoni Armand , Bornancin Michel , Mayer‐Gostan Nicole
Published: June 2005

Branchial sodium uptake was measured across secondary lamellae (SL) using the isolated‐perfused head preparation. This study was correlated with histological examination.

Freshwater trout, Salmo gairdneri, were exposed to various artificial media: distilled water (DW), fresh water (FW: NaCl < 200 μl/1; Ca++ = 1.5 mM/1), FW + 5 mM CaCl2 and FW + 10 mM CaCl2. These environments altered the number and forms of “chloride cells” (CC) located in SL and were related to changes in maximal transport rate of Na+. An increase in a specific type of CC (round) was associated with an increase in Vmax, and a decrease in round cells was associated with a decrease in Vmax.

Relative to FW, exposure to DW increased the density of round cells, FW + 5 mM CaCl2 had no effect, and FW + 10 mM CaCl2 produced an initial degeneration of CC followed by restoration and increase in protruding round cells.

We conclude that secondary lamellar chloride cells play an important role in Na+ uptake.
Studies on the mechanisms of neurulation in the chick: Morphometric analysis of the relationship between regional variations in cell shape and sites of motive force generation
Authors: Nagele Robert G. , Lee Hsin‐Yi
Published: June 2005

Microfilaments, which are organized into bundles in the apical ends of neuroepithelial cells, are generally thought to play a major role in generating the driving forces for neural tube closure. Because of their proximity to the luminal surface, the contractile activity of these microfilament bundles results in conspicuous changes in the overall shape of neuroepithelial cells, most notably apical costriction and apical surface folding. In the present study, we have used morphometric methods and computer‐assisted image analysis to reveal the distribution of microfilament‐mediated forces in the developing midbrain during initial contact of apposing neural folds in chick embryos at Hamburger and Hamilton stage 8+ of development (Hamburger and Hamilton (1951) J. Morphol., 88:49–92). The degree of apical constriction, apical surface folding, and bending of the neuroepithelium was used as a barometer of local microfilament activity. Results indicate that cells forming the floor and midlateral walls of the developing midbrain consistently show a higher degree of apical constriction and surface folding than those at other locations. These same regions of the neuroepithelium also exhibit the greatest degree of bending. We conclude that the principal driving forces for closure of the neural tube, at the level of the midbrain, are concentrated in certain regions of the neuroepithelium (i.e., the floor and midlateral walls of the forming neural tube) rather than uniformly distributed.
Intermittent erythropoiesis in anemic newts
Authors: Frangioni Giuliano , Borgioli Gianfranco
Published: June 2005

A group of 88 newts, Triturus cristatus carnifex (Laurenti), was rendered totally anemic by administering acetylphenylhydrazine (APH) in the breeding water for 48 h at a concentration of 25 mg/liter. The course of erythron restoration was followed for 5 months, sacrificing four specimens per week and analyzing the blood and spleen hemopoietic tissue. The return to the normal values of the red blood cell count occurred through marked increases in concentration at fairly regular intervals, which is best explained by a discontinuous, rhythmic erythropoiesis. This fact is strictly correlated with the intermittent mitotic activity observed in the spleen and with the periodic appearance of large quantities of immature elements in the blood smears. The APH‐induced synchronization of newt erythropoietic activity revealed the approximate length of each erythropoietic cycle to be 4 to 5 weeks and the erythropoietic life span to be 50 to 60 days.
Artificial induction of selfing conjugation in Paramecium bursaria
Authors: Endoh Hiroshi , Watanabe Tsuyoshi , Hiwatashi Koichi
Published: June 2005

In normal conjugation of Paramecium bursaria, pairs always consist of cells of different mating types and no selfing pairs are induced with detached cilia from cells of a complementary mating type. This suggests that the initial ciliary agglutination (the mating reaction) is mating‐type specific but that the subsequent formation of conjugating pairs is not mating‐type specific as in the other species of Paramecium. The mechanism to exclude the formation of selfing pairs in normal conjugation is suggested to be the requirement of long‐lasting specific ciliary adhesion for the formation of firm pairs.
Energy allocation during concurrent pregnancy and lactation in Norway rats with delayed and undelayed implantation
Authors: Oswald Christine , McClure Polley Ann
Published: June 2005

Despite the high cost of lactation alone, concurrent preganncy and lactation (CPL) is widespread among rodents. Many species that exhibit CPL delay implantation of the litter in utero while nursing. The first purpose of this study was to describe the pattern of energy allocation during CPL in a species with a large degree of overlap between gestation and lactation. Resting metabolic rate, food consumption and mass changes of Norway rat dams and litters, digestive efficiency and urinary energy loss of dams, and pup tissue energy equivalents were determined for CPL dams and for dams that were only lactating (C). CPL dams had significantly higher metabolic rates than C dams. Food consumption, pup growth, tissue energy equivalents, and assimilation efficiency were similar for both groups. The energy equivalent of mass change was greater for C dams, which gained in maternal mass (lipid) during lactation, than for CPL dams, which only increased in mass because of the litter in utero. The second purpose of this study was to investigate the suggestion that delayed implantation during CPL evolved as a mechanism to lower peak energy demands during CPL. Concurrently pregnant and lactating dams were injected with estrone (ECPL dams) on days 3–16 of lactation to prevent them from delaying implantation. A group of dams that were only lactating also received estrone injections (EC dams). ECPL dams produced smaller offspring at weaning than EC dams. This effect was more pronounced for large‐littered dams. These results indicate that the increased metabolic cost of a concurrent pregnancy is met by diverting energy into production of pup tissue rather than maternal tissue and that delayed implantation likely evolved as a means to decrease the peak energy demands of CPL.
Effects of FMRFamide on the intact and isolated circulatory system of the pinto abalone, Haliotis kamtschatkana
Authors: Krajniak K. G. , Bourne G. B.
Published: June 2005

The in vivo and in vitro effects of the molluscan tetrapeptide, FMRFamide, were examined on the circulatory system of the pinto abalone, Haliotis kamtschatkana. When perfused through isolated hearts, FMRFamide caused a dose‐dependent increase in heart rate. Injected into the circulation of intact, unrestrained animals, the peptide initially enhanced the rate of beating, augmented the aortic diastolic and pulse pressures, and raised the arteriovenous (AV) pressure difference; but at higher doses, this initial enhancement was followed by a decrease in aortic blood pressure, an increase in efferent ctenidial pressure, and a substantially reduced heart rate. Therefore, FMRFamide could have a role in controlling the circulation of H. Kamtschatkana.
Assessment of embryo viability prior to transfer by the noninvasive measurement of glucose uptake
Authors: Gardner David K. , Leese Henry J.
Published: June 2005

An ultramicrofluorometric technique was used to measure the uptake of glucose by single mouse blastocysts prior to transferring them into the uterus of pseudopregnant foster mothers. Of 50 blastocysts whose glucose uptake was measured prior to embryo transfer, 25 gave rise to male and 13 to female offspring. Twelve embryos failed to develop. The mean glucose uptake of these 12 embryos was significantly below that of those which developed successfully. Female embryos took up slightly more glucose than male embryos.