bluuebunny/crossref_metadata_2025_split huggingface dataset:
The occurrence of elongated intercellular bridges in deep cells of Oryzias embryos during blastula and gastrula stages
Authors: Kageyama Tetsuo 
Published: June 2005

AbstractThe occurrence of an elongated intercellular bridge (IB) connecting a pair of post‐mitotic cells in the middle of which a midbody intervenes has been reported in several lines of cultured cells and on the surface of embryonic epithelia. Using the cell isolation method, this same structure also was revealed to be present in inner blastomeres of the embryo of Oryzias latipes. The IB emerges in the midblastula stage, when cleavage has become asynchronous and deep cells with protruding pseudopodia begin their locomotion through expanding intercellular space. The paired cells interconnected by the IB occupy 7–10% of the total number of deep cells, and some IBs are elongated to as long as 50 μm from the midblastula until the beginning gastrula stage. The IB is produced by incomplete cytokinesis, and it probably elongates itself until it is approximately 5 μm in length. Several lines of evidence suggest that the IB elongates further as sister cells move apart by means of pseudopodia. The fraction of elongated IBs gradually decreases during the gastrula stage, until no IB is observed thereafter. One likely cause of the decrease is that the gastrula has less space for divided cells to separate from each other, preventing the IB from elongating further. Naturally, the maximal and average lengths of the IB decrease as the gastrula stage proceeds.
Cytology, embryology, and evolution of the developmental arrest syndrome in newts of the genus Triturus (Caudata: Salamandridae)
Authors: Sessions Stanley K. , Macgregor Herbert C. , Schmid Michael , Haaf Thomas 
Published: June 2005

AbstractWe have examined embryonic development in three species (T. carnifex, T. cristatus, and T. marmoratus) of European newts of the genus Triturus (subgenus Neotriton) in which developmental arrest occurs in embryos that are homomorphic for a chromosomal heteromorphism involving chromosome 1 (Horner and Macgregor: J. Herpetol., 19:261–270, 1985). Embryonic arrest occurred during tailbud stages in all three species, but at a slightly earlier stage in T. marmoratus. Two phenotypes were identified among the arrested embryos. One of these is indistinguishable in embryonic morphology from normal embryos at all stages up to the time of arrest, but the other is characterized by a protruding yolk plug, which persists from the late gastrula/early neurula stage to the tailbud arrest stage and apparently interferes with normal morphogenesis. Evidence is presented that the two arrested phenotypes, which occur in approximately equal numbers, represent embryos that carry the two alternative homomorphic chromosome pairs of chromosome 1 heteromorphism. We conclude that developmental arrest reflects a balanced lethal heterozygosity probably resulting from an unequal exchange of genic material between the homologues of chromosome 1 which occured in a common ancestor of the Neotriton species.
Maintenance of foreign gene expression and independent chromosome fragments in adult transgenic rainbow trout and their offspring
Authors: Disney Jane E. , Johnson Kenneth R. , Banks Deanna K. , Thorgaard Gary H. 
Published: June 2005

AbstractTransgenic rainbow trout (RT) were generated in earlier experiments by an in vivo modification of the chromosome‐mediated gene transfer technique. This involved fertilizing albino RT eggs with gamma‐irradiated brook (speckled) trout (ST) sperm and then heat shocking the eggs to induce second polar body retention. Striped pigment patterns were stable in six mosaic individuals between the ages of 7 and 14 months. We estimated the total ST DNA contribution in adult transgenic fish using DNA dot blot analyses. An average of 7% ST DNA was obtained in analyses of 11 transgenic individuals. Nine of 55 transgenic individuals examined expressed a ST‐specific isozyme in adulthood; some were mosaic for foreign gene expression. Variable numbers of autonomous chromosome fragments were maintained in 10 adult transgenic individuals examined. Five transgenic RT were backcrossed to albino RT. Chromosome fragments were inherited by 29 of 31 backcross embryos examined. Additional active nucleolar organizer regions (NORs) were present on some fragments and may also have been integrated into some host chromosomes. This method may have numerous applications for basic and applied genetic research in fish.
Experimental induction of claw transformation in snapping shrimps
Authors: Govind C. K. , Wong Anna , Pearce Joanne 
Published: June 2005

AbstractThe effectiveness of various manipulations of the major claw in inducing the contralateral minor claw to transform into a major claw in adult snapping shrimps, Alpheus heterochelis, was studied. While removal of the major claw was 100% effective in inducing transformation, sectioning of its nerve was effective in about two‐thirds of the animals, and tenotomy of its closer muscle was effective in less than one‐half. Occasionally, tenotomy of the opener muscle induced transformation, whereas immobilizing the claw was totally ineffective. This gradation in effectiveness, which is related to the degree of trauma applied to the major claw, suggests a central mechanism regulating bilateral asymmetry of the claws.
Do amiloride and ouabain affect ammonia fluxes in perfused Carcinus gill epithelia?
Authors: Lucu Čedomil , Devescovi Massimo , Siebers Dietrich 
Published: June 2005

AbstractThe effects of inhibitors on the efflux of ammonia (from the basolateral to the apical side, Jb→a) were studied in preparation of isolated Carcinus gills immersed in dilute seawater (DSW) that was identical to the perfusion solution. Adding 10−4M amiloride to the solution bathing the gill preparations reduces the efflux of ammonia by 29% relative to the control value. Under experimental conditions, it appears that only about 1% of the amiloride‐sensitive influx of Na+ (Ja→b) can be exchanged with NH on an equimolar basis.The ammonium ion is apparently transported at the basolateral side by a carrier‐mediated process. Kinetic analyses of the influx of ammonium ions revealed a Km of 36.99 μM and a maximum velocity (Vmax) equal to 19.6 μmol g−1 h−1.Basolaterally applied ouabain (5 × 10−3M) and NaCN (10−3M) reduced the efflux of ammonia by 46.7 and 42.2%, respectively, suggesting an interaction of NH with the basolaterally located Na+/K+ exchanger in which NH appears to be able to substitute for K+.
Selective identification of the paternal mitochondrion in living sea urchin eggs and embryos by chlorotetracycline
Authors: Hinkley Robert E. , Newman Arthur N. 
Published: June 2005

AbstractWhen sea urchin eggs are pretreated with fluorescent chelate probe chlorotetracycline (CTC) and then fertilized with unlabeled sperm, a small, brightly fluorescent particle resembling the mitochondrion of free‐swimming sperm both in size and fluorescent staining characteristics appears in the egg cytoplasm. This particle first appears near the base of the insemination cone and, like the paternal mitochondrion identified in previous ultrastructural studies, remains closely associated with the male pronucleus during its microtubule‐dependent migration toward the egg center. These similarities strongly suggest that the fluorescent particle observed in the cytoplasm of living, CTC‐pretreated sea urchin eggs is, in fact, the mitochondrion of the fertilizing sperm.
Seasonal variation in freeze tolerance and ice content of the tree frog Hyla versicolor
Authors: Layne Jack R. , Lee Richard E. 
Published: June 2005

AbstractFreeze tolerance and ice content of Hyla versicolor showed pronounced variation between summer (June) and winter (December). Summer frogs survived freezing at −3°C for up to 9 hr and ice accumulation up to 50% of their total body water. A time course of ice formation indicated that an equilibrium level was reached in approximately 15 hr. Thus, the lethal ice content was less than the equilibrium ice content for these conditions (63.1%). A second group was induced to enter an overwintering condition by holding them through the summer and then subjecting them to a progressive reduction in temperature and photoperiod for 2 months. These frogs survived freezing for 48 hr at −3°C. Their equilibrium ice content at this temperature was significantly lower (52.5%) than comparably treated summer animals. In the winter acclimatized group, frozen frogs had substantially higher blood glucose levels than unfrozen frogs (22.7 μmol/ml vs. 1.33 μmol/ml), but glycerol levels were not elevated after freezing. Freezing frogs conditioned for overwintering at −7°C resulted in a higher equilibrium ice content (62.6%), but none survived. It is evident that in preparation for overwintering, frogs reduce the amount of ice formed at a given subzero temperature, but there is little indication of a substantial change in the total amount of ice tolerated.
Plasma arginine vasotocin, angiotensin II, and salt gland function in freshwater‐ and seawater‐adapted kelp gulls (Larus dominicanus)
Authors: Gray David A. , Erasmus Theunis 
Published: June 2005

AbstractKelp gulls (mean body weight of 905.3 ± 46.5 g, plasma osmolality of 316.5 ± 1.5 mOsm.kg−1, plasma Na+ of 151.3 ± 0.8 mEq.liter−1, and plasma K+ of 3.1 ± 0.2 mEq.liter−1 (means ± SE) were adapted to fresh water and had basal plasma concentrations of arginine vasotocin (AVT) and angiotensin II (AII) of 13.6 ± 1.1 pg.ml−1 and 48.1 ± 3.4 pg.ml−1, respectively. Adaptation to seawater strengths of 25, 50, 75, and 100% produced significant elevations of plasma osmolality, electrolytes, and AVT concentrations that plateaued with 50% seawater. Body mass and plasma AII levels were not significantly altered.Comparison of salt gland function in birds adapted to fresh water with those adapted to 100% seawater showed some differences in concentrating and secretory capabilities.
Bromocriptine prevents the castration‐induced rise in porphyrin concentration in the harderian glands of the male syrian hamster, Mesocricetus auratus
Authors: Buzzell Gerald R. , Menendez‐Pelaez Armando , Porkka‐heiskanen Tarja , Pangerl Andreas , Pangerl Brigitte , Vaughan Mary K. , Reiter Russel J. 
Published: June 2005

AbstractThe Harderian glands in Syrian hamsters exhibit a striking sexual dimorphism. Male Harderian glands show two cell types and low levels of porphyrins and melatonin. Of the enzymes involved in the synthesis of melatonin, N‐acetyltransferase (NAT) and hydroxyindole‐O‐methyltransferase (HIOMT) show high and low activity levels, respectively. Female Harderian glands show but one cell type and have high porphyrin and melatonin levels, low NAT activity, and high HIOMT activity. In castrated males, the Harderian glands exhibit a female pattern of morphology, porphyrin levels, and indoleamine metabolism. In an attempt to determine whether prolactin is involved in this sexually dimorphic response of the Harderian glands, intact and castrated male and intact female hamsters were injected daily with 500 μg of bromocriptine, a dopamine agonist. Bromocriptine led to reduced serum prolactin levels in all groups. It had no apparent effect on the Harderian glands of intact males. In contrast, in castrated males bromocriptine prevented the postcastrational rise in porphyrin levels but had no effect on NAT or HIOMT activities. In females, bromocriptine treatment had no effect on prophyrin concentrations or HIOMT activity; it led to a statistically significant increase in NAT activity. We propose that testosterone inhibits Harderian porphyrin synthesis while dopamine or prolactin stimulates it.
Interaction of proteins RSV IV and RSV V in rat seminal vesicle secretion
Authors: Manco G. , Sansone G. , Abrescia P. 
Published: June 2005

AbstractThe RSV IV polypeptide, molecular weight ratio (Mr = 10,000), which is produced by the rat seminal vesicle, has previously been suggested to be associated with another polypeptide in the gland secretion (Higgins et al., '76). This study provides that RSV IV is a component of a protein shown by immunoassays, electrophoresis, and amino acid composition analysis to contain, together with RSV IV, the seminal vesicle secretory RSV V polypeptide (Mr = 13,000). This RSV IV‐RSV V complex (namely CFS protein) had an isoelectric point at pH 7.2 and an approximate molecular weight of 22,000 daltons. This complex inhibits the previously reported in vitro binding of the isolated RSV IV to epididymal sperm cells, thus suggesting a functional role for the RSV IV‐RSV V interaction.
Synthesis and activity of Xenopus laevis oocyte tyrosinase
Authors: Kidson S. H. , Fabian B. C. 
Published: June 2005

AbstractThis study investigates the mechanisms that control pigment synthesis in Xenopus laevis oocytes. Although we find the molecular weight of oocyte tyrosinase to be similar to that of amphibian skin, we were unable to increase its activity by proteases or detergents, as has been reported for skin tyrosinase. On the other hand, by measuring the activity of polysomal‐bound enzyme, we were able to correlate increased tyrosinase activity with increased levels of enzyme synthesis. We therefore suggest that in oocytes, the activity of tyrosinase is primarily dependent on its synthesis, whereas in skin, the rate‐limiting step is the post‐translational activation of the enzyme. We speculate on these differences in relation to the functional role of melanin in skin and oocytes.
Histoincompatibility in a low invertebrate, Hydractinia echinata: Analysis of the mechanism of rejection
Authors: Lange R. , Plickert G. , Müller W. A. 
Published: June 2005

AbstractThe colonial hydroid Hydractinia echinata is able to discriminate between self and non‐self. Encounters between isogeneic, or allogeneic but histocompatible, colonies of this hydroid result in fusion, whereas incompatible colonies do not fuse but display a peculiar mode of rejection. A special type of nematocyte, the microbasic mastigophore, which occurs exclusively in the stolon compartment of a colony, migrates to and accumulates at contact sites. Here these nematocytes adjust their cnidocils toward the alien tissue and discharge their threads nearly synchronously. Later incoming nematocytes discharge without delay upon arrival. Nematocytes move to and accumulate at contact sites in both compatible and incompatible encounters. However, only contact between incompatible animals causes the discharge of the nematocytes.Permanent contact between incompatible competitors leads to an increase in the density of microbasic mastigophores from 12 to a maximum of 450 per mm stolon length. As a consequence the stolons acquire a hyperplastic appearance.Labeling experiments indicate that stem cells or precursor cells are sensitive to the contact stimulus shortly before or during the S‐phase of the cell cycle. Differentiation to mature microbasic mastigophores takes 4 days.Upon interruption of contact, the density of microbasic mastigophores is regulated down to the normal level. Supernumerary cells are removed by phagocytosis.
Sperm basic proteins in the turtle Chrysemys picta: Characterization and evolutionary implications
Authors: Chiva M. , Kulak D. , Kasinsky H. E. 
Published: June 2005

AbstractBasic proteins in the sperm nuclei of reptiles have been classified cytochemically as type 3 intermediate proteins (Kasinsky et al., '87) or electrophoretically as type 1 protamines (Elsevier and Pieau, '88) according to Bloch's ('69) classification scheme. In this paper we have purified the sperm basic proteins of the painted turtle Chrysemys picta and show that they display considerable microheterogeneity, like the protamines of some fishes and other vertebrates. In addition, the amino acid composition of C. picta sperm basic proteins is very similar to that of protamines in birds (Chiva et al., '87), although those of the turtle lack tyrosine and contain low amounts of lysine and histidine. These facts allow us to relate reptilian sperm basic proteins to the main evolutionary line of vertebrate protamines and to discuss possible mechanisms for the macroevolutionary trend of relative constancy of sperm basic proteins in reptiles, birds, and mammals.
Neurohumor effects on crustacean haemocyanin oxygen affinity
Authors: Morris S. , McMahon B. R. 
Published: June 2005

AbstractVarious monoamines released as neurohormones from the pericardial organs of crab hearts were found to potentiate the oxygen affinity of haemocyanin from Cancer magister. Of the compounds tested, the catechol dopamine was the most active. Preincubation of the haemocyanin with a dopamine antagonist abolished the effect, indicating a specific site. Haemocyanin may also retard the rapid auto‐oxidation of dopamine that normally occurs at physiological pH.
Thyroid involvement in the relative photorefractoriness of Japanese quail, Coturnix coturnix japonica
Authors: Chaturvedi C. M. , Meier Albert H. 
Published: June 2005

AbstractThyroid involvement in the photosexual response was examined in photosensitive and relative photorefractory Japanese quail. Surgical thyroidectomy was carried out in gonadally regressed adult males held for several months on natural daylengths of 13.5–14.5 h. These birds were considered relative photorefractory (birds that are gonadally regressed at daylengths, 12–15 h, and initially stimulatory for gonadal growth in photosensitive quail). Following thyroidectomy and sham‐operation (controls), one‐half of each group were exposed for 30 days to light:dark (LD) 16:8 and then transferred to LD 13.5:10.5 for another 30 days. The remaining operated quail were exposed for the first 30 days to LD 8:16 and then transferred to LD 13.5:10.5 for another 30 days. In quail examined after the first 30 days, the left testis sizes were greatly increased in both thyroidectomized and control birds held on LD 16:8 but completely regressed in both groups held on LD 8:16. The photosexual responses are characteristic for both photosensitive and relative photorefractory quail held on such daylengths. After the second 30 days, the testes were strongly stimulated in both thyroidectomized and control quail that were transferred from LD 8:16 (first 30 days) to LD 13.5:10.5 (second 30 days). Apparently, photosensitivity had been reestablished during the first 30 days on short daylengths. In quail transferred from LD 16:8 (first 30 days) to LD 13.5:10.5 (second 30 days), the testis sizes were reduced in control birds indicating a relative photorefractory response to this intermediate daylength. However, the testis continued to grow in the thyroidectomized quail transferred from LD 16:8 to LD 13.5:10.5. The results indicate that the thyroid is important in the maintenance of relative photorefractoriness in Japanese quail.
A specific androgen‐binding protein (ABP) in Necturus testis and its zonal distribution
Authors: Singh Sanjay , Callard Gloria V. 
Published: June 2005

AbstractThe urodele amphibian Necturus maculosus has a zoned testis, which is advantageous for separating Leydig cells from germinal elements and for studying stage‐dependent biochemical changes. Using [3H]testosterone (T) in a standard binding assay and dextran‐coated charcoal (DCC) or Sephadex LH‐20 to separate free and bound steroids, we identified an androgenbinding protein (ABP) in Necturus testis cytosols. This protein was of high affinity (Kd = 10−9 M) and was saturable (Bmax = 10−9 M) and specific for androgen (T; 5 α‐dihydrotestosterone, DHT) but could be distinguished from the androgen receptor of Necturus testis by its relative abundance (300–550 fmol/mg protein), short half‐time of dissociation (3 min at 22°), inability to adhere to DNA‐cellulose, and absence from nuclear extracts. Additionally, when analyzed on sucrose gradients, the ABP of Necturus testis sedimented at 6–7 S in both low or high ionic strength buffers. In that estradiol (E2) is a poor competitor for T‐binding, this protein resembles a sex steroid‐binding protein previously identified in urodele serum but differs from the ABP and testosterone‐estradiol‐binding globulin (TEBG) of rodents, humans, goldfish, and sharks. It is differentially distributed within the testis, with the highest levels in immature lobular regions composed of Sertoli cells and germ cells in premeiotic stages and lower levels in regions composed primarily of Leydig cells. The cellular source and function of this protein in Necturus testis remain to be determined.
Localization of angiotensin‐converting enzyme in the trout gill
Authors: Olson Kenneth R. , Lipke David W. , Kullman Dixie , Evan Andrew P. , Ryan James W. 
Published: June 2005

AbstractAngiotensin‐converting enzyme (ACE) was localized in perfused trout gills by measuring gill extraction of two radiolabeled ACE inhibitors, 125I‐351A (an iodinated derivative of lisinopril) and 3H‐RAC‐X‐65, and by autoradiography of gills perfused with 125I‐351A. A 125I‐351A pulse was preferentially extracted by the arterio‐arterial (AA) pathway (61.7% ± 1.8% extraction; mean ± SE, N = 4); the arteriovenous (AV) pathway extracted an additional 10%. Extraction by either pathway was reduced by simultaneous perfusion with 10−5 M unlabeled lisinopril. AA extraction of RAC‐X‐65 during continuous perfusion was maximal (75% ± 5%, N = 6) during the first few minutes of perfusion and decreased steadily to 38% ± 9% by 20 min and to less than 10% by 40 min. AV extraction of RAC‐X‐65 was negligible. Autoradiography of gills continuously perfused with 125I‐351A showed that the radiolabel was concentrated in the respiratory lamellae. The highest grain density was associated with the pillar cells nearest the medial (inner) lamellar margin. Afferent filamental arteries and afferent lamellar arterioles were labeled to a lesser extent. Relatively little label was found on the efferent lamellar arterioles or efferent filamental arteries. 125I‐351A binding was not evident in AV vessels. These findings support the hypothesis that the gill is an important site for formation of plasma angiotensin II and they suggest that enzymes associated with mammalian endothelial cells are also common to gill pillar cells.
Two histospecific enzyme expressions in the same cleavage‐arrested one‐celled ascidian embryos
Authors: Whittaker J. R. , Meedel Thomas H. 
Published: June 2005

AbstractFertilized eggs of the ascidian, Ciona intestinalis, were prevented from undergoing cytokinesis but not nuclear division by treatment with cytochalasin B. After appropriate times, such cleavage‐arrested multinucleate zygotes developed acetylcholinesterase of larval tail muscle and an alkaline phosphatase ordinarily localized in the larval endoderm tissues. Separate histo‐chemical reactions on one of a pair of samples taken from the eggs of single animals provided examples (6/34) in which the numbers of cytochalasin‐treated embryos displaying the respective reaction product overlapped sufficiently (15–29%) to indicate that some of the zygotes had developed both enzymes in the same uncleaved single cell. With an actual dual‐staining technique that can be applied to single cleavage‐arrested zygotes, 62% of those developing a strong alkaline phosphatase reaction also had a strong acetylcholinesterase reaction. In other experiments, quantitative measurements of enzyme activity in homogenates of 114 single cleavage‐arrested zygotes confirm directly that 18% of the zygotes produce both enzymes. There was no obligatory mutual exclusion of the potential for simultaneous expression of two tissue‐specific characteristics that would ordinarily be segregated into different lineages during early cleavages. The cytoplasmic determinants believed responsible for these histotypic expressions can apparently function independently in the same cell.