bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pattern regulation between hind‐ and forelimbs after blastema exchanges and skin grafts in Notophthalmus viridescens
Authors: Rollman‐Dinsmore Christine , Bryant Susan V. 
Published: June 2005

AbstractExperiments were performed to ascertain whether cells from the forelimb and the hindlimb of newts share a common pattern‐regulating mechanism during regeneration. In one series of experiments early digit hindlimb and forelimb blastemas were exchanged either ipsilaterally or contralaterally. In a second experimental series, a strip of forelimb skin was added to a slit in a homologous site on the hindlimb or in a site 180° removed from the position of origin, and vice versa (hindlimb skin into forelimb). After contralateral blastema exchanges, supernumerary limbs developed in addition to the limb of graft origin, whereas after ipsilateral exchanges, a single limb of graft origin regenerated. Limbs in which skin grafts were inserted into homologous sites developed normal regenerates of the host type, while in contrast, limbs with supernumerary digits regenerated from limbs which had received skin grafts in positions 180° opposite to the homologous position. The results of both experiments were dependent on the positional disparity between the graft and host tissues, and they suggest that the forelimb and hindlimb do indeed utilize a common mechanism for pattern regulation.
Timing of gastrulation in fused double‐embryos formed from eggs with different cleavage schedules in the starfish, Asterina pectinifera
Authors: Mita I. , Satoh N. 
Published: June 2005

AbstractThe aim of this study is to explore the control mechanism which regulates, the timing of gastrulation. We wished to know whether the timing is rigidly determined within the constituting cells of the embryo or whether it is changed by intercellular communication systems. Starfish‐fused double‐embryos were formed by contact between pairs of denuded eggs with different cleavage schedules, one egg in each pair being distinguished with vital stain. Electron microscopy revealed identical ultrastructural characteristics in every cell contact: Septate junctions were found not only between cells in the contact area between the two counterparts constituting a fused embryo but also between cells within a counterpart. In fused embryos formed from stained eggs and unstained eggs with the former having started the first cleavage 30 min earlier than the latter, the stained counterparts began to invaginate about 30 min earlier than the unstained. When fused embryos were produced by putting stained eggs in contact with unstained eggs which had begun the first cleavage 2 hr later than the stained eggs, gastrulation of the stained counterparts took place about 2 hr earlier than that of the unstained counterparts. These results suggest that the timing of gastrulation is fixed within the cells of an embryo and cannot be altered in spite of the cell‐to‐cell communication that appears to exist.
The effect of sperm concentrations during preincubation and at insemination on fertilization of rat eggs in vitro
Authors: Nishimura H. , Niwa K. , Miyake M. , Iritani A. 
Published: June 2005

AbstractRat epididymal spermatozoa, at a concentration of 40–65 × 104 cells/ml, were preincubated for 5–5.5 hr and then added to eggs from superovu‐lated, immature rats. By 10–12 hr after insemination, 86% of the eggs had undergone fertilization, but many of them (41%) were polyspermic. When sperm were preincubated at almost the same concentration and for the time stated above, but then diluted to 1–3 × 104 cells/ml before insemination, the number of fertilized eggs and the incidence of polyspermy were both reduced, being 56% and 5%, respectively. When a sperm concentration of 1–3 × 104 cells/ml was used both during preincubation and at insemination, the fertilization rate and the degree of polyspermy were essentially zero. To achieve a fertilization rate of 60% or more, with polyspermy not in excess of 10%, a sperm concentration of 30–100 × 104 cells/ml during preincubation and then diluted to approximately 1–3 × 104 cells/ml at insemination appears to be optimal.
The effects of antisperm plasma membrane antibodies on sperm‐egg binding, penetration, and fertilization in the pig
Authors: Peterson R. N. , Robl J. M. , Dziuk P. J. , Russell L. D. 
Published: June 2005

AbstractA procedure using published surgical techniques is described for determining the effects of antiplasma membrane antibodies on sperm‐egg binding, penetration, and fertilization in vivo in the domestic pig. Time of ovulation was controlled and sperm inseminated at precise times relative to ovulation. Sperm were exposed to antibodies (Fab) and then washed free of excess antibody and placed in one uterine horn near the uterotubal junction. Sperm exposed to control material were placed in the opposite horn as a control. One horn was tied with two ligatures near the body of the uterus. Eggs were collected by flushing the oviducts at prescribed times after insemination. In nine animals used for this study, antibodies to boar sperm plasma membranes completely blocked sperm‐zona binding, penetration of the zona, and fertilization. In contrast, sperm were bound to the zona pellucida and penetrated eggs in every case on the control side. These results indicate that insemination in vivo is useful in screening antibodies produced against specific plasma membrane antigens to determine their role in fertilization.
Taurine transport by isolated flounder renal tubules
Authors: King Patricia A. , Beyenbach Klaus W. , Goldstein Leon 
Published: June 2005

AbstractPrevious in vivo clearance studies (Schrock et al., '82) have revealed that taurine is secreted by marine fish kidneys. In the present study taurine secretion by the flounder (Pseudopleuronectes americanus) renal tubule was investigated by assaying the transport of 14C‐taurine in vitro. Collections from isolated fluid‐secreting flounder tubules confirmed the presence of a tubular mechanism for taurine secretion. The flounder renal tubule concentrated taurine in the lumen at a lumen/bath ratio of 25, with the movement across the peritubular membrane identified as the concentrating step of taurine transport. Studies with teased flounder renal tubules identified transport as Na+ and Cl− dependent. Taurine transport was inhibited by β alanine, γ‐aminobutyric acid, and hypotaurine. In a study of the hormonal control of taurine transport, only the adrenal steroid dexamethasone stimulated taurine uptake by the flounder renal tubules. Transport was not affected by the second messengers adenosine 3′5′‐ cyclic monophosphate, guanosine 3′5′‐cyclic monophosphate, adenosine, or Ca++ ionophore (A12384).
Studies of mitosis in excised limb regenerates of the newt, Notophthalmus viridescens
Authors: Tomlinson B. L. , Globus M. , Vethamany‐Globus S. 
Published: June 2005

AbstractSubsequent to excision and explantation of the limb blastema into culture medium, there is an abrupt reduction in mitotic index lasting several hours. Coincident with the disappearance of mitosis, abnormal mitotic figures (AMFs), lacking the condensed chromosomal nature of normal figures, are seen. These persist until normal levels of mitotic activity are restored approximately 6 hr later. The transient loss of mitotic activity is observed in both ganglionated and nonganglionated explants. The large number of prophase figures observed at time zero were sharply reduced within minutes, without concomitant increases in the later phases. The possibility that some cells, without completing mitosis, become temporarily indistinguishable as mitotic figures, is discussed in terms of chromosomal decondensation and recondensation.
Culture of 9½‐day rat embryos in human serum supplemented and unsupplemented with rat serum
Authors: Reti Leslie L. , Beck Felix , Bulman Stephanie 
Published: June 2005

AbstractWe attempted to grow explanted 9½‐day rat embryos in vitro in human serum but were unable to demonstrate normal growth as has been previously described. The embryos were consistently smaller, anaemic, and frequently deformed. These abnormalities were overcome by supplementing the human serum with 10% rat serum. The latter possibly provides yet unidentified essential growth factors required by rat embryos that are not present in human serum.
Inhibition of vacuolar membrane fusion by intracellular symbiotic algae in Hydra viridis (Florida strain)
Authors: O'Brien Timothy L. 
Published: June 2005

AbstractHydra viridis (Florida strain) forms a stable symbiotic association with unicellular Chlorella‐like algae. Algae are phagocytized by hydra phagocytes and maintained individually within vacuoles of the host‐cell. The purpose of the studies presented in this paper was to determine how symbiotic algae avoid host‐cell digestive processes. Viable symbiotic algae were found to inhibit the fusion of the algal vacuolar membrane and vacuoles labeled with thorium dioxide. By contrast, thorium‐labeled vacuoles did fuse with vacuoles containing nonviable algae. Further, the absence of acid phosphatase activity within vacuoles containing established symbiotic algae implies that inhibition of membrane fusion by algae in hydras prevents the conversion of the algal vacuoles into phagolysosomes.
The program of Hl histone synthesis in S. purpuratus embryos and the control of its timing
Authors: Harrison M. Frances , Wilt Fred H. 
Published: June 2005

AbstractThe program of H1 histone synthesis was investigated in Strongylocentrotus purpuratus embryos in order to determine when the late Hl histones are synthesized. The embryos were staged by cell number, morphological stage, and chronological age. Care was taken to ensure that conditions of rearing the embryos remained consistent. Labelling with 3H‐lysine revealed that two forms of early Hl (Hlα1, and Hlα2) are synthesized from early cleavage stages (16–32 cells) to the blastula stage. Hlα1, synthesis ceases first at around 400 cells (hatching blastula); Hlα2 continues to be synthesized by the blastula but is usually absent from the labelling pattern in early gastrula (700 cells). Two forms of late Hl γ appear sequentially during the pre‐hatching blastula stage. Hl γ appears at 200–250 cells and Hl β approximately 1 hr later, at 250–300 cells. The late forms of H2A and H2B are first synthesized at around hatching, several hours after late Hl forms appear. The time of synthesis of late Hl is strictly controlled by a chronological clock and is not affected by disruption of the cell cycle, cessation of DNA synthesis, or alteration of nucleocytoplasmic ratios. Polyspermic embryos and hydroxyurea‐arrested embryos followed the normal temporal program of on‐ set of late Hl synthesis.
Genes involved in regulating the melanocyte and melanoblast‐melanocyte populations in the epidermis of newborn mouse skin
Authors: Hirobe Tomohisa 
Published: June 2005

AbstractIn the dorsal epidermis of both C57BL/10J and C3H/He mice, the number of melanocytes positive to the dopa reaction increased from birth to 3 or 4 days of age, and then gradually decreased and disappeared by 30 days of age. However, the number of melanoblasts plus melanocytes positive to the combined dopa‐premelanin reaction remained constant until 3 or 4 days of age and then decreased in both strains. Despite the similarity of the change in these populations from birth on, there was a significant difference in the number of such cells between the two strains. Both melanocytes and melanoblasts in C3H/He were fewer than in C57BL/10J mice.The F1, F2, and backcross matings were performed in order to gain some information about the genetic basis of the difference. In the F1 generation the offspring from reciprocal crosses exhibited intermediate values in both populations. The F2 generation included the C3H/He type, F1 type, and C57BL/10J type in a ratio of about 1:2:1 in both populations. Moreover, both reciprocal backcrosses gave ratios of parent type to F1 type, which did not differ significantly from 1:1 in either population. These results indicate that the melanocyte and melanoblast‐melanocyte populations in the dorsal epidermis of newborn mouse skin are controlled by semidominant genes.
In vitro synthesis and secretion of ecdysteroids by Drosophila melanogaster ovaries
Authors: Rubenstein Elaine C. , Kelly Thomas J. , Schwartz Margaret B. , Woods Charles W. 
Published: June 2005

AbstractThe ovaries of adult Drosophila melanogaster were shown to produce and secrete ecdysteroids in vitro by an ecdysteroid radioimmunoassay. The major secretory products were determined by HPLC/RIA analysis to be ecdysone, 20‐hydroxyecdysone, and a highly polar fraction. Based on competitive binding studies, the secreted ecdysteroids contain 2–3 times more 20‐hydroxyecdysone than ecdysone.
The leg flexor muscle of Carcinus. I. Innervation and excitatory neuromuscular physiology
Authors: Parsons D. W. 
Published: June 2005

AbstractThe innervation and neuromuscular physiology of the flexor muscles in the legs of Carcinus were investigated using a variety of histological and electrophysiological techniques. Slow muscle fibers were found in the proximal and distal regions of the muscle; intermediate‐ and fast‐contracting fibers were found in most regions, but fast fibers predominated in the central regions. Muscle fibers were innervated by one to four excitatory axons. The extent of inhibitory innervation was not determined. The motor innervation showed significant departures from the previously described Brachyuran pattern. The results indicated the need for a thorough reexamination of the patterns of limb innervation of the crustacean tribes.
Comparison of antifreeze glycopeptides from arctic and antarctic fishes
Authors: O'Grady Scott M. , Schrag Joseph D. , Raymond James A. , Devries Arthur L. 
Published: June 2005

AbstractAntifreeze glycopeptides from the Atlantic tomcod Microgadus tomcod), saffron cod (Eleginus gracilis), and Greenland cod (Gadus ogac) were isolated by ion exchange chromatography. Polyacrylamide gel electrophoresis revealed that fewer sizes of antifreeze glycopeptides are present in the serum of M. tomcod and E. gracilis compared to the Antarctic nototheniid (Dissostichus mawsoni), Glycopeptide 6 from M. tomcod and E. gracilis as well as glycopeptide 8 from G. ogac were sequenced and compared with known sequences of similar‐sized glycopeptides from Antarctic fishes. It was found that arginine residues in glycopeptide 6 from E. gracilis and M. tomcod occur at positions 15 and 18, that proline periodically replaces alanine (ala) at positions 7, 13, and 19. In contrast, none of the antifreeze glycopeptides from Antarctic fishes contain arginine. Threonine (thr) occupies positions 15 and 18 instead. Glycopeptide 8 from G. ogac was found to have the same sequence as glycopeptide 8 from the polar cod (Boreogadus saida). The results indicate that the repeating sequence (ala‐ala‐thr) appears to be highly conserved within polar fishes. However, greater variation in antifreeze glycopeptide structure exists within one family of northern cods (Gadidae) than within species belonging to four separate families of Antarctic fishes.
Quail nuclear marker is lost during in vitro culture
Authors: Yaross Marcia S. , Konigsberg Irwin R. 
Published: June 2005

AbstractJapanese quail cells when cultured in vitro lose the characteristic nuclear morphology that distinguishes them from chick cells. To determine if the nuclear marker is regained if cultured cells are reimplanted in ovo, a double marker experiment was performed. Quail neural crest cells, which include melanocyte precursors, were cultured in vitro and implanted into chick embryos. Although many of the resulting quail melanocytes exhibit the characteristic quail morphology, others do not. Thus, if donor cells are cultured in vitro prior to transplantation into chick hosts, the possibility that cells of quail origin are present but indistinguishable from host tissue must be considered.
The effect of the dorsal region in reversed orientation on the development of the embryonic chick wing
Authors: Searls Robert L. 
Published: June 2005

AbstractDorsal right wing myogenic mesoderm, with or without ectoderm, that had been labeled with tritiated thymidine, was grafted into the dorsal right wing myogenic region in reversed proximal‐distal and cranial‐caudal orientation. When a graft of ectoderm and mesoderm was in reversed orientation, the graft increased in length, width, and thickness. A similar graft in normal orientation increased only on the axis of the humerus. A graft of mesoderm alone in reversed orientation increased in length and thickness, like a graft in normal orientation, but increased in width like a graft of ectoderm and mesoderm in reversed orientation. During normal wing development, a groove develops at the base of the wing ventral to the ninteenth somite due to the ventral movement of the lateral body wall proximal to the base of the wing. A graft in normal orientation participated in the formation of the groove if placed in a position where it was appropriate to do so. A graft in reversed orientation did not participate in the formation of the groove, although it did not block the ventral movement of the lateral body wall proximal to the base of the wing. When the groove did not form, the humerus did not separate from the lateral body wall and the humerus was short. Increase in size of the graft in inappropriate directions caused grafted myogenic cells to be present in inappropriate amounts and locations. Ectopic cartilage differentiated from the grafted cells present in inappropriate locations.
Acceleration of acrosome reaction in hamster spermatozoa by lysolecithin
Authors: Ohzu Eiji , Yanagimachi Ryuzo 
Published: June 2005

AbstractWhen hamster spermatozoa were preincubated for 1–2 hr in Ca2+‐containing medium and then exposed to lysolecithin (LC), large proportions of the spermatozoa underwent acrosome reactions within 15 min. These acrosome‐reacted spermatozoa were capable of fertilizing eggs. The earliest visible sign of the reaction, wrinkling of the acrosomal cap, seen by 30 sec after exposure to LC. The reaction in many spermatozoa was completed within the next 30 sec.
Volume regulation in an intertidal nemertine, Procephalothrix spiralis coe. I. Short‐term effects and independence of decerebration
Authors: Ferraris Joan D. , Schmidt‐Nielsen Bodil 
Published: June 2005

AbstractIn the Nemertina both neurosecretory cells in the cerebral ganglia and neuroglandular structures (cephalic glands and cerebral organs) have been found to be responsive, on a cytological level, to changes in the osmolality of the worm's environment. However, the volume or osmoregulatory capacities of these worms are scarcely known. The present study examines water, ion, and volume regulation in an intertidal nemertine and the effects of removal of the cerebral ganglia and the cephalic glands on these parameters.Control, sham‐operated, and decerebrated (ablated) Procephalothrix spiralis were acutely transferred to diluted seawaters. Osmolality and Na, K, and Cl (mEq/liter) concentrations were determined in total tissue water after various exposure periods. Extracellular volume was determined, in vitro, as the fraction of the total tissue water in which 14C‐polyethylene glycol was distributed.Control, sham‐operated, and ablated P. spiralis all responded to diluted seawaters in the same manner with no significant difference among groups. In diluted media, the worms demonstrated hyperosmotic conformity. Tissue osmolality decreased rapidly in all groups at similar rates indicating no effect of ablation on integumental water permeability. Significant volume regulatory responses were observed in all worms starting 15 minutes after exposure. Based on the very small extracellular volume (∼5% of total body water) of P. spiralis, measured volume regulatory events in this species primarily reflect intracellular phenomena. Initially, osmolality decreased while water content (gm H20/gm solute free dry weight) increased. During this period, volume regulation was accomplished by the elimination of Na, Cl, and unmeasured solutes (μmoles or μosmoles/gm s.f.d.w.) which limited water gain. Subsequently, osmolality was constant and all worms demonstrated a slow regulatory volume decrease. The solutes that accompanied volume loss were also Na, Cl, and substantial amounts of unmeasured solutes.
Cyclic nucleotides during chondrogenesis: Concentration and distribution in vivo and in vitro
Authors: Ho Wai Chang , Greene Robert M. , Shanfeld Joseph , Davidovitch Z. 
Published: June 2005

AbstractThis study correlates endogenous levels of cAMP and cGMP with their immunohistochemical localization during chondrogenic differentiation of C57B1/6J mouse limb mesenchyme in vivo and in vitro. A transient decrease in cGMP but not cAMP was found from days 12 to 13 in vivo correlating with early stages of chondrogenesis in the developing limb. Intracellular levels of both cAMP and cGMP in high density limb mesenchyme cultures increased 25% after 24 hr in culture when aggregate and nodule formation was detectable. When cells were seeded at different initial plating densities to delay the onset of aggregate and nodule formation, increased levels of intracellular cAM Pcorrelated temporally with the appearance of nodules. Both cyclic AMP and cGMP were immunohistochemically localized in perichondrial cells and chondrocytes in vivo and in vitro. Therefore, (1) cAMP levels correlated temporally with the appearance of chondrogenic cells and (2) cAMP and cGMP were immunohistochemically localized to chondrogenic cells.These data indicate that fluctuations of both cAMP and cGMP levels may be involved in limb cartilage differentiation. Although increases in both nucleotides were found to correlate with the onset of chondrogenesis in vitro, in vivo data suggest that the amount of cAMP relative to cGMP rather than the absolute amount of an individual cyclic nucleotide may be more significant in modulating differentiation.
Origin of melanosome structures and cytochemical localizations of tyrosinase activity in differentiating epidermal melanocytes of newborn mouse skin
Authors: Hirobe Tomohisa 
Published: June 2005

AbstractThe mode of differentiation of epidermal melanocytes was studied by ultrastructural cytochemistry in the skin of newborn mice of strain C57BL/10J. From observations of epidermal melanoblasts and melanocytes, stage I melanosomes, including both unit membranes and inner matrices, appear to be formed from Golgi vacuoles or rough endoplasmic reticulum (RER). Stage I melanosomes were positive to ammoniacal silver‐nitrate reaction in the melanoblasts of 1‐day‐old mice. All stages of melanosomes were similarly positive in the differentiating melanocytes of 2‐day‐old mice. However, Golgi apparatus, RER, and vesicles were negative. Therefore, it is conceivable that structural proteins, originated from Golgi vacuoles or RER, are developed into specialized proteins and are detected by this reaction in stage I melanosomes. Stage I melanosomes were dopa‐negative in the melanoblasts. Stage I and II melanosomes were similarly negative in the differentiating melanocytes. Thus, the melanoblasts are thought to begin production of stage I melanosomes prior to the onset of tyrosinase activity. In the differentiating melanocytes, dopa‐melanin depositions were observed in stage III and IV melanosomes, trans Golgi saccules, and small vesicles derived from these saccules, but not in RER. These vesicles were in contact with, or fused to, melanosomes. These findings suggest that tyrosinase may be transferred by Golgi vesicles into stage I and II melanosomes originating from Golgi vacuoles or RER.