bluuebunny/crossref_metadata_2025 huggingface dataset:
Endogenous opioid peptide system in male brown bullhead catfish, Ictalurus nebulosus lesueur: Characterization of naloxone binding and the response to naloxone during the annual reproductive cycle
Authors: Rosenblum Paul M. , Callard Ian P.
Published: June 2005

The endogenous opioid peptide system was investigated in male brown bullhead catfish. 3H‐naloxone binding was assessed in 20,000g membrane preparations from catfish brains. 3H‐naloxone bound to a high‐affinity, low‐capacity receptor (Kd = 0.27nM; Bmax = 119.52 fmol/mg protein) and a low‐affinity, high‐capacity receptor (Kd = 5.77 nM; Bmax = 323.06 fmol/mg protein). Binding was ligand and tissue specific. 3H‐naloxone binding was regionally distributed, with highest levels in telencephalon:preoptic area, and lower levels in remaining diencephalon, mesencephalon, and cerebellum:brain stem. A seasonal cycle in receptor number was observed, with highest numbers occurring during testicular recrudescence in association with elevated plasma androgens. In vivo naloxone treatment resulted in decreased levels of testosterone and 11‐ketotestosterone during testicular recrudescence but had no effect during the resting phase. These data indicate the presence of an endogenous opioid peptide system in brown bullhead catfish which is involved in the regulation of reproductive function in this species.
Identification of Xenopus laevis sperm and egg envelope binding components on nitrocellulose membranes
Authors: Lindsay Leann L. , Hedrick Jerry L.
Published: June 2005

Interacting egg envelope and sperm surface components were identified for Xenopus laevis using blotting methods. Sperm were extracted with sodium dodecyl sulfate (SDS), the extracted proteins separated by gel electrophoresis and blotted, and the blots treated with 125I‐labeled heat solubilized envelopes. The converse experiment was also performed where envelope components were separated by gel electrophoresis, blotted, and the blots treated with 125I‐labeled sperm components. Blotted sperm components with apparent molecular weights of 14K, 19K, 25K, and 35K selectively bound the solubilized envelopes. All of the envelope binding components were found to be localized on the sperm surface by radioiodinating intact sperm using lodo‐Gen. The blotted egg envelope component with an apparent molecular weight of 37K selectively bound to solubilized sperm components, and this binding was due to the protein moiety of the glycoprotein. 125I‐labeled heat solubilized envelopes from unfertilized and fertilized eggs showed the same pattern of binding to blotted sperm components. Selected sulfated carbohydrates (fucoidan, dextran sulfate, and heparin, but not chon‐ droitin sulfate) inhibited fertilization and binding of 125I‐labeled heat solubilized envelopes to blotted sperm extract. Thus, the binding of heat solubilized envelopes to electrophoretically separated and blotted sperm proteins may reflect cellular interactions.
Oogenesis in Fundulus heteroclitus. V. The relationship of yolk vesicles and cortical alveoli
Authors: Selman Kelly , Wallace Robin A. , Barr Valarie
Published: June 2005

Yolk vesicles, which first appear in small oocytes, are morphologically indistinguishable from cortical alveoli, which are present in eggs. Both types of membrane‐limited vesicles show identical staining properties with both classical dyes for acidic glycoproteins and with fluorescein‐labeled lectins for specific carbohydrate moieties. Lectin (Dolichos biflorus agglutinin)‐affinity chromatography was used to isolate from yolk vesicle‐stage follicles a > 200‐kilodalton (kDa) glycoconjugate that had been shown previously to be synthesized within the oocyte and to reside within yolk vesicles. Antiserum was prepared against the > 200‐kDa glycoconjugate and was used on immunoblots to demonstrate the presence of a substance both in yolk vesicle‐stage follicles and eggs that was immunoreactive. Indirect immunolabeling of plastic sections of various size follicles and eggs demonstrated that the antibody reacted with a substance found only in yolk vesicles and cortical alveoli. Thus, a combination of approaches (morphological, biochemical, and immunological) have been used to confirm the earlier cytological observations that suggested that yolk vesicles of small oocytes give rise to cortical alveoli of eggs. We suggest, therefore, that the term “yolk vesicle” is a misnomer since these structures, when mature, ultimately release their contents into the perivitelline space at fertilization, rather than serve as a source of nutrients for the embryo.
In vitro differentiation of male germ line cells from sea urchin testis
Authors: Poccia Dominic
Published: June 2005

Fragments of sea urchin testicular tissue were cultured at 15°C in serum‐supplemented seawater for 5 weeks. Cells whose DNA had been pulse‐labelled with 3H‐thymidine at the beginning of the experiment were followed by autoradiography, and counts were made of the proportions of each male germ‐line cell type from sections of tissue at several time points. Differentiation of spermatogonia to mid‐spermatids occurred within the first 10 days, with a decline of about 40% in the total number of spermatogonia and an increase of 250% in the number of mid‐spermatids. Thereafter, no changes occurred in the proportions of germ‐line cells, although tissue integrity was maintained throughout. The results indicate that sea urchin male germ‐line cells can complete meiosis and the first stages of spermiogenesis including nuclear condensation and cytoplasmic reduction in culture with kinetics similar to those in vivo. The system should permit analysis of factors responsible for male germ‐cell differentiation.
In vitro effects of calmodulin antagonists on macrophage function in the posterior necrotic zone of the chick wing
Authors: Brewton Randolph G. , MacCabe Jeffrey A.
Published: June 2005

Excised tissues from the prospective posterior necrotic zone (pPNZ) of the stage 21 chick wing were cultured in the presence of the calmodulin antagonists/protein kinase C inhibitors trifluoperazine (TFP) or chlorpromazine (CPZ). The appearance of cell death in vitro was not affected by the drugs. Macrophages differentiated normally and were competent to engulf debris. Lysosomal fusion with phagosomes and the digestion of most debris also occured in the presence of the drugs. However, the macrophages were unable to process internalized cell membranes properly and continued accumulating membrane until they were grossly distended. The effect was reversible upon removal of the drugs. The results suggest a role for calmodulin and/or protein kinase C in the proper recycling of internalized membrane in embryonic macrophages.
Do ascidians possess the ancestral subunit type of vertebrate lactate dehydrogenase?
Authors: Baldwin J. , Mortimer K. , Patak A.
Published: June 2005

The tetrameric lactate dehydrogenases (LDH) of vertebrates contain three major subunit types, A, B, and C, that are assumed to have arisen by gene duplication. Ammo acid sequence comparisons imply that the A‐B duplication occurred among the lower chordates and that the duplication separating the C subunit from the A and B subunits is even older. In this evolutionary scheme, which conflicts with earlier interpretations, the C subunit of modern vertebrates resembles most closely the ancestral subunit type of vertebrate LDH.

Lactate dehydrogenase was purified from the ascidian Pyura stolonifera, subphylum Urochordata. The enzyme occurs as a single L‐lactate specific homotetramer with a molecular weight of about 39,000, and with kinetic properties that resemble the LDHA4 isozymes of higher vertebrates. Amino acid compositional analysis and immunochemical titration of LDH activity provide strong evidence that the single ascidian LDH subunit is more closely related to the teleost C than to the teleost A or B subunits. In addition, immunochemical comparisons demonstrate affinities with hagfish LDHB4. It is suggested that the ascidian and teleost C subunits represent the ancestral subunit type of vertebrate LDH and that the lamprey subunit and the hagfish B subunit may be related more closely to this ancestral subunit than to the A and B subunits of gnathostomes.
Sources of calcium and phosphorus during embryogenesis in bullsnakes (Pituophis melanoleucus)
Authors: Packard Mary J. , Packard Gary C.
Published: June 2005

The yolk of eggs of bullsnakes (Pituophis melanoleucus) contains an average of 88 mg of calcium and 23 mg of phosphorus at oviposition. Calcium and phosphorus in yolk decline dramatically during the growth phase of development, and residual yolk removed from hatchlings contains only 3 mg of calcium and 1 mg of phosphorus. Thus, bullsnake embryos deplete the yolk of virtually all of its calcium and phosphorus, and residual yolk does not contain sufficient quantities of these ions to support significant posthatching growth. Calcium and phosphorus in embryos increase during incubation, and carcasses of hatchlings contain an average of 113 mg of calcium and 21 mg of phosphorus. Total calcium content (calcium in yolk plus calcium in carcass) of eggs increases significantly from 88 mg at oviposition to 116 mg at the end of incubation, but total phosphorus content of eggs does not vary significantly. Embryonic bullsnakes obtain about 24% of their calcium from the eggshell but rely on the yolk for all of their phosphorus. Bullsnake embryos seemingly mobilize considerably more calcium than is required for skeletogenesis. This excess calcium may be stored in endolymphatic sacs, but the functional significance of such deposits is unknown.
Stability of the glandular morphogenesis produced by retinoids in the newborn hamster cheek pouch in vitro
Authors: Covant H. A. , Hardy Margaret H.
Published: June 2005

Retinoids can induce alterations in differentiation and morphogenesis in the hamster cheek pouch. In order to determine the stability of these changes, explants of neonatal pouch were exposed to 6 μg/ml of either retinyl acetate (RAc: 1.8 × 10−5 M) or all‐trans retinoic acid (RA: 2.0 × 10−5 M) for an initial 3 of 7 days, out of a total of 21 days in organ culture. Three days of RAc or RA caused a delay in the differentiation and keratinization of the epithelium at least up to day 7 of culture. Additionally, two out often explants exposed to RA showed small downgrowths of epithelium into the stroma at 7 or 14 days. Seven days of exposure to either retinoid led to inhibition of epithelial keratinization, and produced a mucous metaplasia which was still seen at the end of the 21‐day culture period. Periodic acid‐Schiff (PAS)–positive, diastase‐resistant material was present in the metaplastic epithelium, in intercellular, and in some instances, intracellular locations. An excess of either RAc or RA, for 7 days, induced persistent glandlike downgrowths of epithelium, suggesting that a stable alteration in the developmental program of the epithelium may have occurred. Many of these downgrowths possessed a lumen which was lined by cuboidal epithelium and contained PAS‐ positive, diastase‐resistant secretory material. RA appeared more potent than RAc in inhibiting keratinization, in producing a mucous metaplasia, and in initiating glandlike downgrowths. The persistence of glandular downgrowths suggests that retinoids, either directly or indirectly, act in a manner similar to that of an embryonic inductor.
In vivo ovarian uptake and processing of vitellogenin in the rainbow trout, Salmo gairdneri
Authors: Tyler Charles R. , Sumpter John P. , Bromage Niall R.
Published: June 2005

The in vivo uptake and processing of vitellogenin (VTG) into developing oocytes of rainbow trout were studied. Oestrogenized trout injected with 32P and 3H‐leucine incorporated these labels into newly synthesized vitellogenin. This dual‐labelled VTG was purified from the serum and injected intraperitoneally into sexually maturing female trout. The 32P. 3H‐VTG was readily taken up from the peritoneal cavity into the blood, without degradation, and thus became available for sequestration by developing oocytes. Ovarian uptake of 32P. 3H‐VTG was very rapid. Eight h after injection, approximately half of the labelled VTG was in the blood, but this figure had fallen to 12% after 48 h, and to 0.2% after 2 weeks. This fall in blood 32P. 32H‐VTG level coincided with increases in the level of both radiolabels in the ovary. Eight hours post‐injection, a significant amount of 32P. 32H‐VTG was found in the ovary homogenate. Most of this material was intact, primarily representing VTG bound to the follicle surface. However, small amounts were contained within the follicles and probably represented newly sequestered VTG which had not yet been degraded into the yolk proteins, lipovitellin and phosvitin. Twenty‐four hours post‐injection, approximately 25% of the injected 32P. 3H‐VTG had been sequestered by the ovary. Although a small proportion of the labels were associated with intact VTG, the majority of the 3H and 32P eluted with lipovitellin and phosvitin, respectively, the yolk proteins derived from VTG. After 2 weeks, nearly 70% of the 32P. 3H‐VTG initially injected had been incorporated into the ovaries, all of which was present as labelled yolk proteins. The rate of uptake of VTG was highest in the fish with the largest follicles, where it approached 120 ng.mm2 follicle surface h−1. The results demonstrate that both the uptake and processing of VTG by trout oocytes are rapid features that are reflected in the rate of ovary growth seen during exogenous vitellogenesis.
Catfish plasma lipoproteins: In vivo studies of apoprotein synthesis and catabolism
Authors: Smith M. A. K. , McKay M. C. , Lee R. F.
Published: June 2005

Three distinct lipoprotein classes, very‐low‐density (VLDL), low‐density (LDL), and high‐density (HDL), were isolated from plasma of channel catfish, Ictalurus punctatus. HDL was the major lipoprotein class, accounting for 22–32% of the total plasma protein. The major peptide of VLDL and LDL was an apoB‐like protein (molecular mass 250,000 daltons). When a protease inhibitor was added to the plasma, there was no evidence of apoC‐ or apoE‐like proteins in catfish VLDL. The major peptide of HDL in male catfish was an apoAI‐like peptide (molecular mass 25,000 daltons). The major peptide of the HDL of female catfish undergoing vitellogensis had a molecular mass of 92,000 daltons. Plasma lipoprotein metabolism was investigated by measurement of plasma titers and the synthesis and catabolic rates of apoVLDL, apoLDL, and apoHDL. Apoprotein synthesis rates (ks) were measured in fed, 3‐day‐fasted, and 20‐day‐fasted channel catfish by continuous infusion of 14C‐tyrosine. In vivo synthesis rates of plasma apoproteins have not been previously measured. Analysis of data required the derivation of a series of equations that accounted for the kinetics of secretion of plasma proteins and their equilibration with an extravascular compartment. The plasma titer of apoVLDL was closely correlated to dietary intake, although apoVLDL synthesis rates did not significantly change with fasting. ApoLDL plasma titers significantly decreased after a 20‐day fast but not after a 3‐day fast. Fasting resulted in a significant increase in apoLDL synthesis. The apoHDL titer and synthesis rates were not significantly affected by fasting. Male and female fish have similar apoVLDL and apoLDL titers and synthesis rates. ApoHDL plasma titers and synthesis rates were significantly higher in females (14.0 ± 1.6 mg ml−1; ks = 34.9% ± 15.3% day−1) than in males (9.0 ± 1.6 mg ml−1; ks = 8.7% ± 2.6% day−1). The higher apoHDL titer and synthesis rate in female fish were due to the presence of a peptide (molecular mass 92,000 daltons) not present in males.
Thyroid status influences in vitro thyrotropin and growth hormone responses to thyrotropin‐releasing hormone by pituitary glands of hatchling slider turtles (Pseudemys scripta elegans)
Authors: Denver Robert J. , Licht Paul
Published: June 2005

The effects of thyroidal feedback on thyrotropin (TSH), growth hormone (GH) and prolactin (PRL) secretion by pituitary glands, and on TSH responsiveness of thyroids in hatchling turtles, Pseudemys scripta elegans, were investigated by in vitro techniques. Pituitaries were stimulated in culture with 0, 1, 10, or 100 ng/ml thyrotropin‐releasing hormone (TRH) at intervals up to 36 hr; hormones were estimated by RIA. TSH release was elevated by all doses of TRH during the first 2 hr of stimulation (1.8 to 3.6‐fold) and secretion rates increased further during the following 4 hr, with a dose response between 1 and 10 ng/ml TRH. TSH release then returned to initial basal levels and showed the same response to TRH on the second day. GH secretion was also elevated by all doses of TRH tested. A progressive increase in basal GH secretion over time in vitro suggested that GH might normally be under inhibitory control. Medium concentrations of PRL were nondetectable at all times and thus were not measured in subsequent experiments. In vitro thyroxine (T4) secretion by thyroids from these same turtles showed a dose response when stimulated with 5–20 ng/ml purified sea turtle TSH for 8 or 20 hr.

Treatment of turtles in vivo with 0.5 μg T4 at 2 hr or daily for up to 2 wk prior to sacrifice greatly reduced in vitro basal TSH secretion and the response to 10 ng/ml TRH. In contrast, several of the T4treatments significantly elevated basal GH secretion. Plasma TSH was markedly elevated after 4 wk treatment with a goitrogen, methimazole, and this was accompanied by increased basal TSH secretion and responsiveness to TRH by pituitaries in vitro; basal GH secretion was reduced but the response of GH to TRH was unaffected. The response of in vitro thyroidal T4 output to TSH was augmented in hyperthyroid animals (⩾ 1 wk T4) and was abolished by methimazole treatment. These data demonstrate a clear thyroidal feedback in the regulation of chelonian TSH secretion and are consistent with an involvement of TRH in the control of pituitary TSH and GH. While the site(s) of the inhibitory actions of T4 are unknown, changes in the functional properties of the pituitary thyrotropes are involved; the somatotropes appear to be less dependent on T4.
Pathways of inorganic carbon fixation in the endosymbiont‐bearing lucinid clam Lucinoma aequizonata. Part 1. Purification and characterization of the endosymbiotic bacteria
Authors: Distel D. L. , Felbeck H.
Published: June 2005

Two simple techniques by which the sulfur‐oxidizing endosymbiotic bacteria may be purified from the bacteriocyte tissues of the marine bivalve Lucinoma aequizonata, are described. Tissue homogenates are prepared from symbiont‐containing tissues, and symbionts are recovered by centrifugation through gradients of Percoll density gradient medium. The high density of the endosymbionts (probably because of the presence of numerous sulfur deposits within the cells) allows clean, rapid, and efficient separation of these cells from host cells and cell constituents. Light and electron microscopy and enzymatic and biochemical techniques are used to demonstrate the identity, quality, and purity of the symbiont isolates from this lucinid clam. The techniques described here for L. aequizonata, have also been used successfully to purify sulfur‐oxidizing endosymbionts from a variety of marine invertebrates, including the bivalves L. annulata, Lucina floridana, Calyptogena magnifica, and Codakia orbicularis, and from the vestimentiferan tubeworms Riftia pachyptila, and Tevnia jerichonana. Such preparations should prove useful for investigating these and similar sulfur‐oxidizing symbioses.
Pathways of inorganic carbon fixation in the endosymbiont‐bearing lucinid clam Lucinoma aequizonata. Part 2. Analysis of the individual contributions of host and symbiont cells to inorganic carbon assimilation
Authors: Distel D. L. , Felbeck H.
Published: June 2005

The incorporation of 14C from H14CO−3 into acid‐soluble metabolites was examined in the endosymbiont‐containing gills and purified symbionts of the lucinid clam Lucinoma aequizonata. HPLC, paper chromatography, and enzymatic techniques were used to identify and quantify compounds into which label was incorporated in continuous and pulse‐labeling experiments. Both symbiont and host cells fix carbon in considerable quantities; however, each incorporates carbon into a distinctly different subset of compounds. In intact gills the initial carbon fixation product is malate. Label subsequently accumulates in succinate, glucose phosphate, glutamate, alanine, and glycogen. In the symbiont cells carbon is incorporated into aspartate, 3‐phosphoglycerate, malate, and citrate. Purified symbionts incorporate carbon into the same compounds in the same proportions as do symbionts that are exposed to labeled H14CO−3 while still within the host tissues. Under the conditions tested, purified symbionts released no significant quantities of labeled compounds into the incubation medium.
A quantitative study of command elements for abdominal positioning behavior in the crayfish Procambarus clarkii
Authors: Larimer James L. , Pease Craig M.
Published: June 2005

We develop a statistical method to estimate the total number of command elements devoted to abdominal positioning behavior in crayfish. We assumed that all command elements can be identified, that each identified cell is equivalent to a tagged individual in a population, and that the cells were sampled randomly. Samples of 29, 30, 20, and 35 cells from abdominal ganglia A3, A4, A5, and A6, respectively, were taken from our catalog. We characterized each cell using several morphological and physiological criteria, determined how many times each identified cell was present in the sample, and estimated the total number of command elements using both a maximum likelihood method and a modification of the Lincoln index. The larger the proportion of identified cells seen only once in the sample, the more identified cells there were that were unrepresented in the sample. We estimate there are approximately 34, 60, 86, and 98 command elements in ganglia A3, A4, A5, and A6, respectively.

Using a slightly different data set we show that the motor output of unipolar cells is more often stronger in the direction of the cell's axonal projection. In bipolar command elements, the output strength was uncorrelated with the relative sizes of the two projecting axons.

No two cells in our sample were completely identical, and this morphological variability sometimes made it difficult to determine whether or not two cells obtained from different individuals were the same identified cell. We discuss why caution should be exercised in studies requiring precision in cell identification.
Culture of newt cells from different tissues and their expression of a regeneration‐associated antigen
Authors: Ferretti Patrizia , Brockes Jeremy P.
Published: June 2005

We have established culture conditions for cells from normal limb, early limb regenerate (blastema), heart, and liver of the newt Notophthalmus viridescens. Whereas heart and liver cells had a relatively short life in culture, limb cells have shown no sign of senescence over more than 1 year in culture. Cultured cells from all these tissues express to differing extents the regeneration‐associated antigen 22/18. The antigen is intracellular and filamentous, and its expression appears to be regulated by culture density. Furthermore, 22/18 antigen is turned off in limb and blastemal cultures following differentiation into muscle, as also occurs in vivo.
Electrophysiological study of the effects of cardiodilatin 1–16 on the frog spinal cord in vitro
Authors: De Santis A. , Cariello L. , Miralto A. , Russo P. , Tota B.
Published: June 2005

Using the isolated spinal cord of the frog, hemisected and further divided into two distinct quadrants, we studied electrophysiological changes produced by peptides present in the atrial natriuretic factor (ANF) preprohormone. ANF and related peptides (atriopeptin I and atriopeptin III) did not affect the frog spinal cord. The 1–16 fragment from cardiodilatin (10−5 M) induced slow depolarization in ventral and dorsal nerve stumps. The depolarization was associated with an increase of the evoked dorsal root potentials and depression of the fast component of the reflex responses. When depolarization approached its maximum value, spontaneous slow potentials appeared progressively similar to the evoked potentials, and became rhythmic until they reached a frequency of one potential every 15–20 seconds. The effects of cardiodilatin 1–16 are localized at dorsal horn level. It is suggested that this substance exerts a modulatory effect on frog cord physiology.
Chronic low humidity‐stress in the lizard Anolis carolinensis: Changes in diurnal corticosterone rhythms
Authors: Summers Cliff H. , Norman Mark F.
Published: June 2005

Plasma corticosterone levels of female lizards (Anolis carolinensis) were sampled at 4‐h intervals before and after a photothermal regimen known to stimulate ovarian growth in January and February, respectively. Female A. carolinensis have a diurnal cycle in plasma corticosterone with a daily peak at 1700 h in lizards with unstimulated ovaries exposed to short photophase and low temperature (12L 20°C:12D 20°C). Stimulation of ovarian growth by increasing the temperature and lengthening the photophase (14L 32°C:10D 20°C; 80% relatively humidity) caused an 8‐hr shift in the phase of the corticosterone peak to 0900 h. In lizards exposed to stimulatory temperature and photoperiod but also to low humidity (<35%) corticosterone exhibited a biphasic rhythm, with peaks at both 0900 and 1700 h. These results suggest that conditions which stimulate reproductive activity also cause a phase shift in the daily rhythm of plasma corticosterone. The results also suggest that chronic low humidity during these stimulatory conditions creates a biphasic rhythm of plasma corticosterone in this species. Therefore, a natural condition, low humidity, may be a chronic stressor of the lizard Anolis carolinensis.
Directional cell movement during early development of the teleost Blennius pholis: II. Transformation of the cells of epithelial clusters into dendritic melanocytes, their dissociation from each other, and their migration to and invasion of the pectoral fin buds
Authors: Trinkaus J. P.
Published: June 2005

After clusters of pigmented epithelial cells have rested immobile in the yolk sac of Blennius pholis for 2–4 days (Trinkaus, '88), their constituent cells transform into mesenchymal, dendritic melanocytes. Then these melanocytes dissociate from one another and migrate directionally toward the developing pectoral fin bud (PFB) on either side. Each of these changes takes place in a proximodistal sequence, starting with the epithelial cluster closest to each PFB. Even individual clusters conform to this sequence, the proximal side dissociating first. Eventually, all melanocytes reach and invade the PFB. This is a 100% efficient morphogenetic cell movement. At the completion of this developmental sequence, each PFB is filled with melanocytes arranged in an arc with their filopodia extending outward and the yolk sac is bereft of pigment cells. The form and surface activity of these cells in relation to their motility and to their rate of movement are considered in detail. Attempts to understand the forces involved in giving directionality to these cell migrations are described. Finally, the significance of these observations for morphogenetic cell movements generally and for the relation between epithelial and mesenchymal cells is discussed briefly.
Extraretinal photoreception in lacertilian tail regeneration: The lateral eyes are not involved in photoperiodic photoreception in the Gekkonid lizard, Hemidactylus flaviviridis
Authors: Ndukuba Patrick I. , Ramachandran A. V.
Published: June 2005

The tail of the Gekkonid lizard, Hemidactylus flaviviridis was autotomized and subjected to eight different photoperiodic lengths during the period of tail regeneration, namely, (1) continuous light (LL: LD 24:0) of high intensity; (2) continuous light (LL: LD 24:0) of low intensity; (3) continuous (total) darkness (DD: LD 0:24); (4) normal light and darkness (NLD: LD 12:12); (5) 18 hours light and 6 hours darkness (LD 18:6); (6) 6 hours light and 18 hours darkness (LD 6:18); (7) 16 hours light and 8 hours darkness (LD 16:8); and 8) 8 hours light and 16 hours darkness (LD 8:16). In an attempt to determine the potential contribution of the lateral eyes, or vision, on photoperiodic photoreception in H. flaviviridis during the process of tail regeneration, some animals had both the lateral eyes surgically removed (bilateral orbital enculeation) and the enucleated animals were exposed, along with the normal (unoperated) ones, to the various photoperiodic regimes. Our observations demonstrate that blinded Hemidactylus regenerate their lost (autotomized) tails similar to their sighted (unoperated) counterparts and under LL, LD 18:6, and LD 16:8 better than sighted (unoperated) animals exposed to DD and NLD experimental lighting regimens. We, therefore, conclude that photoperiodic control of regeneration in the Gekkonid lizard, H. flaviviridis is mediated entirely by extraretinal photoreceptor(s) situated in the brain region of the head. Having established that the lateral eyes, or retinae, do not participate in photoperiodically significant photoreception and under the presumption that an extraretinal light receptor(s) may be involved, we discuss the pineal organ as the possible transmitter of the photic stimulus in these animals.
Effects of in vivo beta‐adrenoceptor blockade on hepatic carbohydrate metabolism in rainbow trout
Authors: Moon T. W. , Walsh P. J. , Perry S. F. , Mommsen T. P.
Published: June 2005

Rainbow trout, Salmo gairdneri, received intraarterial injections of saline or the beta‐adrenoceptor antagonist propranolol 1 h prior to sacrifice. Liver glycogen content in vivo and glycogen depletion, total glucose production, lactate gluconeogenesis, and oxidation in isolated hepatocytes in vitro were assessed. A significant handling‐induced glycogen depletion was prevented by prior beta‐adrenergic blockade. Reported maximal glycogen phosphorylase activities could not account for the apparent rate of glycogen depletion. Glycogen depletion continued throughout the hepatocyte isolation procedures and the rates were independent of the presence of propranolol. Epinephrine (5 × 10−7 M) or dibutyryl cAMP (1 × 10−5 M) stimulated total glucose production and lactate gluconeogenesis but not oxidation. Prior beta‐adrenoreceptor blockade depressed total glucose production, but the extent of epinephrine or dibutyryl cAMP activation was independent of the presence of propranolol in the incubation. Gluconeogenesis was depressed but only in the presence of propranolol. These results suggest that stress‐induced catecholamine surges during the preparatory phase of hepatocyte isolation in rainbow trout modify the carbohydrate metabolism of these cells during incubation.
Epinephrine stimulates prostaglandin synthesis by bullfrog lung from warm‐acclimated, but not cold‐acclimated, animals
Authors: Herman Ceil A. , Martinez Jeanelle M.
Published: June 2005

Exogenous prostaglandins (PGs) have been shown to have differing effects on frog lung contractility. In this study, prostaglandin synthesis was measured in lung tissues from warm‐acclimated (WA, 22°C) and cold‐acclimated (CA, 5°C) American bullfrogs, Rana catesbeiana, incubated for 30 min at 5° or 22°C. Media were assayed by radioimmunoassay for PGE2, PGF2α, 6‐keto PGF1α (the metabolite of PGI2), and thromboxane (TX)B2 (the metabolite of TXA2). PGE2 was produced in greatest quantity by tissues from WA and CA animals, at both incubation temperatures. Epinephrine stimulated PGE2, PGF2α, and TXB2 synthesis at 22°C but only stimulated PGE2 production at 5°C. In tissues from CA frogs, epinephrine did not stimulate prostaglandin synthesis at either incubation temperature. Ibuprofen (10−5 M) inhibited basal and epinephrine‐stimulated prostaglandin synthesis in tissues from WA frogs incubated at 22°C. The beta receptor antagonist propranolol (10−6M) blocked the epinephrine‐stimulated synthesis of PGE2, PGF2α and TXB2, suggesting epinephrine stimulates prostaglandin synthesis through beta receptor activation. The absence of stimulation by epinephrine in lung from CA animals, but not in 5°C incubations of tissues from WA animals, suggests that a modification of beta receptors occurs during prolonged cold exposure.
Effects of epinephrine and norepinephrine on glucose release from chinook salmon (Oncorhynchus tshawytscha) liver incubated in vitro
Authors: Sheridan Mark A. , Muir Nancy A.
Published: June 2005

The effects of two catecholamines, epinephrine (EP) and norepinephrine (NE), on carbohydrate metabolism were studied by incubating chinook salmon liver in vitro. Basal release of glucose over the course of a 5‐h incubation was 7.93 ± 1.70 μmol/g dry weight. Both EP and NE (2 × 10−7 M) stimulated glucose release rapidly during the first hour. After 5 h, EP and NE significantly increased glucose release over basal levels to 43.55 ± 9.01 and 32.75 ± 6.17 μmol/g dry weight, respectively. Epinephrine‐ and NE‐stimulated glucose release was dose dependent, with a minimum effective dose of 10−9 M. ED50 for both agents was approximately 2 × 10−7 M; maximal stimulation occurred at 10−5 M. No difference in potency between the two catecholamines was found. The effects of adrenergic agonists and antagonists were also studied. Alpha‐agonists, methoxamine and phenylephrine, had no effect on glucose release. Isoproterenol, a β‐agonist, stimulated glucose release in a manner similar to EP. The β‐antagonist, propranolol, inhibited both catecholamine‐ and isoproterenol‐stimulated glucose release. Alpha‐antagonists (phentolamine, prazosin, and yohimbine) had no effect on either catecholamine‐ or isoproterenol‐stimulated glucose release. Epinephrine and NE stimulate glycogen phosphorylase activity; propranolol inhibits catecholamine‐stimulated phosphorylase activity. These results indicate that catecholamines stimulate glucose mobilization in salmon liver by promoting glycogenolysis mediated through β‐adrenergic receptors.
Distribution and genetic basis of arginine kinase in wild type and flightless mutants of Drosophila melanogaster
Authors: James Judith M. , Collier Glen E.
Published: June 2005

Arginine kinase (AK) activity in Drosophila melanogaster has been localized to specific tissues, traced through developmental stages, and inferred to be the product of a single gene. AK is most abundant in muscle, particularly in larval and adult body‐wall muscle and digestive tract, and in adult indirect flight muscle (IFM) and legs. Low but detectable levels are present in larval imaginal discs, brain, salivary glands, and adult head and reproductive tract. Electrophoretic analysies of a series of developmental stages, as well as prepupal and adult tissues, show only one cytoplasmic isozyme. Since an allozymic variant has the same altered electrophoretic mobility in all stages and tissues, a single structural gene is inferred for AK. A variety of flightless mutants were compared to wild type in regard to AK activity and distribution.
Chronic low humidity‐stress in the lizard Anolis carolinensis: Effects on ovarian and oviductal recrudescence
Authors: Summers Cliff H.
Published: June 2005

Anoline lizards, such as Anolis carolinensis, live in humid regions of the Americas and reproduce during the rainy seasons or when sufficient moisture is available. The present experiment was undertaken to elucidate the effect of low relative humidity on ovarian and oviductal recrudescence in A. carolinensis. The experiment was done in January, when ovaries and oviducts are quiescent. Warm temperatures and long photophase (14L32°C: 10D20°C) elicited ovarian and oviductal growth in lizards kept under high relative humidity (>80%). Chronic low humidity (<35%), however, severely retarded ovarian growth in lizards treated with stimulatory temperature and light. Although the ovaries grew slightly, oviductal growth was completely blocked by low humidity. These results suggest that low humidity may be an environmental cue for A. carolinensis, signalling low available moisture and inappropriate conditions for reproduction.
Evidence suggesting a role for sperm metalloendoprotease activity in penetration of zona‐free hamster eggs by human sperm
Authors: Díaz‐Pérez Eneida , Thomas Paul , Meizel Stanley
Published: June 2005

It has been reported that metalloendopotease (MEP) activity is involved in somatic cell membrane fusion events and in the sea urchin sperm acrosome reaction (AR). MEP activity also has been demionstrated in human and other mammalian sperm. The present study was concerned with investigating whether a human sperm MEP is important in membrane events necessary for sperm egg fusion. Ejaculated human sperm were washed, capacitated in vitro, and preincubated with the competitive MEP inhibitors phosphoramidon (50 μM) or CBZ‐L‐phenylalanine (1 mM), with 100 μM diethylenetriaminepentaacetic acid (DTPA), a heavy metal chelator, or as controls, with the appropriate solvents. The AR was initiated in vitro with preovulatory human follicular fluid and the sperm washed to dilute inhibitors and then coincubated with zona‐free golden hamster eggs (zonae and cumuli removed with trypsin and hyaluronidase, respectively). Eggs were washed after 0.5 h, and the number of sperm remaining bound was counted. After 2.5 h further incubation, the eggs were stained with acetolacmoid or acetoorcein and penetration was assayed by counting the number of decondensed sperm heads per egg (penetration index) and the percent of penetrated eggs. The inhibitor treatments did not decrease the percentage of penetrated eggs (range 80–90%), but a significant reduction in the penetration index was observed. Phosphoramidon reduced the penetration index by 45%, CBZ‐L‐phenylalanine by 57%, and DTPA by 56%. None of the inhibitors decreased the penetration index or the percentage of penetrated eggs when added directly to suspensions of acrosome‐reacted sperm and zona‐free eggs at the diluted levels that would have been present after washing inhibitor‐treated sperm. Other studies demonstrated that the MEP inhibitors did not inhibit sperm motility, sperm binding, the occurrence of the AR, the loss of acrosomal matrix and AR vesicles, or sperm head decondensation. Phosphoramidon also significantly decreased the penetration index when the AR was initiated by the calcium ionophore ionomycin. These results suggest that during the AR, a human sperm MEP is involved (directly or indirectly) in modifying the sperm plasma membrane so as to increase its potential for fusion with the egg plasma membrane.
Effects of cyclic AMP on the spontaneous meiotic maturation of cumulus‐free bovine oocytes cultured in chemically defined medium
Authors: Homa Sheryl T.
Published: June 2005

The rate of spontaneous meiotic maturation and the period of commitment to this process were determined in bovine oocytes devoid of surounding cumulus cells, cultured in chemically defined medium with bovine serum albumin in the absence of serum. The effects of compounds that are known to elevate levels of intracellular cyclic adenosine monophosphate (cAMP) on the resumption and progression of meiosis were investigated. Bovine oocytes were mass‐harvested, dended of cumulus cells, and cultured in 2A‐BMOC medium supplemented with 0.5% bovine serum albumin. Intracellular cAMP levels were indirectly modified using 8‐bromo‐cAMP, bibutyryl cAMP (dbcAMP), forskolin, or 3‐isobutyl‐1‐methyl xanthine (IBMX). Meiotic maturation was scored cytogenetically. Ninety percent of denuded bovine oocytes mature after 24 h, with 65% progressing beyond anaphase I. These oocytes remain at the germinal vesicle (GV) stage for up to 8 h in culture. GV breakdown (GVBD) occurs in 40.5% of oocytes at 9 h. The peak times for the different meiotic stages were 12 h for diakinesis, 15 h for late diakinesis to metaphase I, 20 h for metaphase I, and 24 h for telophase I. By 48 h, most had reached metaphase II. There is a 2‐h lag period between the time at which they become irreversibly committed to mature (at 7 h) and when they demonstrate GVBD (at 9 h). Incubation for 12 h with high concentrations for 8‐bromo‐cAMP and forskolin significanly inhibited GVBD, while the effect of dbcAMP was similar but less pronounced. By 24 h, most of the control and dbcAMP‐treated oocytes were at anaphase I or beyond, while the majority of oocytes treated with 8‐bromo‐cAMP or forskolin had only progressed to metaphase I. Prolonged cultures for 44 h revealed no significant difference in the proportion of treated oocytes reaching anaphase I. to metaphase II compared with controls. IBMX inhibited GVBD in a dose‐dependent manner following 24‐h cultrue, and at low concentrations its effects was similar to that observed for high concentration of 8‐bromo‐cAMP and forskolin. The timing of observation is thus crucial for interpreting the effects of these compounds on bovine oocyte maturation. The results suggest that elevation of intracellular cAMP induces a transitory inhibition of bovine oocyte GVBD. Although the bovine oocyte plasma membrane contains adenylate cyclase, it may also possess an active phosphodiesterase that could prevent dbcAMP and forskolin from raising intracellular levels of cAMP suffeciently to maintain meiotic arres for any considerable time. As 8‐bromo‐cAMP is only partially hydrolyzed by phosphodiesterase, there may be more of this analogue available to stimulate cAMP‐dependent protein kinase, which could account for the more pronounced effect observed with 8‐bromo‐cAMP compared with dbc‐AMP.
Acidic macromolecules associated with the mineral phase of scleractinian coral skeletons
Authors: Constantz Brent , Weiner Stephen
Published: June 2005

Macromolecules intimately associated with the mineral phase of two species of scleractinian coral skeletons are extracted in different ways and partially characterized in some detail for the first time. They are shown to contain an assemblage of glycoproteins in which the protein moiety is rich in acidic amino acids and the carbohydrate moiety contains sulfated polysaccharides. In the presence of calcium, the proteins partially adopt the β‐sheet conformation. The properties of these macromolecules are all consistent with their fulfilling some as yet unidentified roles in controlling mineralization. Furthermore, their properties are similar in many respects to macromolecules present in the mineralized tissues of diverse organisms.
Effects of some β‐carbolines on the concentrations of 5‐hydroxytryptamine, dopamine, and some related metabolites in the cerebral ganglia of the cockroach (Periplaneta americana)
Authors: Sloley B. Duff
Published: June 2005

The effects of the β‐carbolines, harmaline, harmalol, harmane, and harmine on 5‐hydroxytryptamine, dopamine, and tryptophan concentrations in the cerebral ganglion of the cockroach (Periplaneta americana) were investigated. Injection of harmaline and harmine‐induced decreases in the concentrations of 5‐hydroxytryptamine and dopamine. The 5‐hydroxytryptamine depletion was greater than the dopamine depletion. Injections of harmalol had no effect. Tryptophan concentrations were variable, although significant decreases were observed in harmaline‐treated animals. N‐acetyl 5‐hydroxytryptamine, 5‐hydroxyindoleacetic acid, and 5‐hydroxytryptophan remained below the level of detection in all tissues examined, indicating that these compound do not accumulate within the central nervous system as a result of the various treatments.
Lipoproteins I and II from the hemolymph of the blue crab Callinectes sapidus: Lipoportein II associated with vitellogenesis
Authors: Lee Richard F. , Puppione Donald L.
Published: June 2005

Two different high density lipoproteins were isolated and characterized in the hemolymph of blue crabs (Callinectes sapidus). Lipoprotein I was found in both sexes and comprised one peptide (112,000 daltons) and lipid, primarily phosphtidyl choline. Lipoprotein I properties included a hydrated density of 1.12 g/ml, sedimentation coefficient of 5.4 Svedberg flotation units and a protein to lipid ratio of 1.0. This lipoprotein is assumed to have a role in transporting lipid from the hepatopancreas to other tissues. Lipoprotein II had three peptides (190,000, 107,000 and 78,000 daltons), phosphatidyl choline as the major lipid, a hydrated density of 1.16 g/ml, a sedimentation coefficient of 10.4 Svedberg flotation units, a protein to lipid ratio of 1.1, and a yellow to orange color due to a mixture of carotenoids. Lipoprotein II was found only in female crabs undergoing vitellogenesis. Lipoprotein II appeared after 30 days in females that had mated and completed their final molt. The maximum concentration was reached in 50 to 60 days. Lipoprotein II was not present in recently molted females in a collection of crabs from one esturine river but was present in all other stages with highest concentrations (up to 8 mg/ml hemolymph) in stages 5 and 6 (females with large, well developed ovaries). Crab ovaries had a lipoprotein similar to hemolymph Lipoprotein II. Lipoprotein II probably plays an important role in carrying lipid and specific peptides to ovarian tissues. Crustacean hemolymph lipoproteins show some similarities to insect lipophorins, but are quite different from vertebrate lipoproteins.
Nuclear transplantation of rat embryos
Authors: Kono T. , Shioda Y. , Tsunoda Y.
Published: June 2005

The nuclei from one‐, two‐, four‐, and eight‐cell rat embryos were transferred into enucleated zygotes and development to term of the reconstituted embryos, after transfer to recipients, was examined. The rate of electrofusion of enucleated zygotes with karyoplasts was quite high (81–92%), but the fusion rate was only 8% when Sendai virus (HVJ) was used. A large percentage of the enucleated zygotes that received pronuclear karyoplasts developed to the two‐cell stage in vitro (89%) and to term (22%) after transfer to recipient rats. Although 67%, 57%, and 67% of enucleated zygotes receiving nuclei from two‐, four‐ and eight‐cell embryos, respectively, developed to the two‐cell stage, they failed to develop to term after transfer.
Effects of teratogenic antibodies on cultured visceral yolk‐sac endodermal cells: Cytotoxicity and morphological studies
Authors: Cheewatrakoolpong Boonlert , Leung Christopher C. K.
Published: June 2005

Primary cultures of visceral yolk‐sac (VYS) endodermal cells were used to assess the effects of teratogenic and nonteratogenic antibodies. When assessed by cytotoxicity assay, teratogenic antibodies appeared to be lethal to the cultured cells at high concentrations (1.25‐5 mg of antibodies per ml of culture medium). At a nonlethal dosage, the teratogenic antibodies induced morphological changes, including retraction and rounding up of living cells. The cytotoxic effect as well as the effect on cell morphology appeared to be dose‐dependent and specific to VYS endodermal cells. The mechanisms of cell killing were not the same as those attributed to complement‐mediated cell lysis. The nonteratogenic antibodies did not have any cytotoxic effect nor did they cause any cell morphological alterations. The results of this investigation, when interpreted by correlating the dose‐dependent effects of the teratogenic antibodies on cultured endodermal cells with the in vivo teratogenic effect, suggest that teratogenic antibodies when given at a teratogenic dose cause congenital abnormalities without killing the VYS endodermal cells.
Tilapia prolactin stimulates estradiol‐17β synthesis in vitro in vitellogenic oocytes of the guppy Poecilia reticulata
Authors: Tan C. H. , Wong L. Y. , Pang M. K. , Lam T. J.
Published: June 2005

Oocytes at different stages of growth were isolated from the guppy and incubated with and without increasing doses (0.01 to 1000 ng/ml) of a tilapia prolactin (tPRL188). Measurement of the estradiol‐17β secreted into the medium showed that estrogen synthesis from endogenous precursors was stimulated by tPRL at all stages of oocyte growth. In all cases, the maximal stimulating dose was 1 ng/ml. At this dose, the magnitude of the stimulation in estradiol‐17β synthesis was greatest (77%) in oocytes at the beginning of vitellogenesis. These results strongly suggest a role of prolactin in ovarian steroidogenesis of the guppy, and it is possible that this action of prolactin constitutes an additional control mechanism regulating estrogen synthesis in the fish.