bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of acetylcholinesterase during embryogenesis of the ascidian Ciona intestinalis
Authors: Meedel Thomas H. , Whittaker J. R. 
Published: June 2005

AbstractWe have characterized the embryonic muscle cell cholinesterase of the solitary ascidian, Ciona intestinalis (L.). The effects of selective enzyme inhibitors and the inhibition of enzyme activity at high concentrations of substrate suggest that the muscle cell enzyme is an acetylcholinesterase (E. C. 3.1.1.7). After gastrulation and before hatching, acetylcholinesterase activity increased 35‐ to 40‐fold; after hatching (18 hours postfertilization) this activity continued to increase, leveling off at about 36 hours of development. Histochemical observations showed that before hatching acetylcholinesterase was located principally in the muscle cells of the tail and, after hatching, it began to develop in cells of the adult musculature and brain. Inhibition of protein synthesis by puromycin and of RNA synthesis by actinomycin D, suggest that both protein and RNA synthesis were required for the increase in acetylcholinesterase activity observed in unhatched embryos. Although the continued increase in enzyme activity during embryonic development was sensitive to puromycin at all times tested, the actinomycin D sensitivity of this increase was restricted to a discrete time that was completed by about 11 hours of development.
Lizard and newt tail regeneration: A quantitative study
Authors: Baranowitz S. A. , Maderson P. F. A. , Connelly T. G. 
Published: June 2005

AbstractAlmost perfect fits of the Gompertz equation to the growth in length of tail regenerates in the lizard, Lacerta lepida, and the newt, Notophthalmus viridescens, were obtained. Comparison of certain parameters of the equation with published mitotic index data suggests that the Gompertz equation characterizes each system at least from the time that significant mitotic activity is first observed histologically. An objective method for comparing the regeneration periods of the two species is described and applied.A unified hypothesis derived from consideration of properties of the Gompertz equation successfully accounts for the following phenomena reported, but previously unexplained, in the literature: (1) proximal amputations result in longer regenerates than do distal amputations; (2) proximal amputations elicit greater absolute rates of elongation (in mm/day) than do distal amputations; (3) the percent replaced of the length removed is rather constant, regardless of the absolute length regenerated; and (4) one of the parameters of the Gompertz equation appears to be lognormally distributed in a regenerating population. (See text for references.)A computerized interactive graphical system for normalizing growth equations of individual regenerates and integrating the mathematical model with potential candidates for biological control factors is briefly described.
Ultrastructural changes in cells associated with interkinetic nuclear migration in the developing chick neuroepithelium
Authors: Nagele Robert G. , Lee Hsin‐Yi 
Published: June 2005

AbstractChanges in fine structure of cells associated with interkinetic nuclear migration in the developing chick neuroepithelium were investigated. Interphase cells are elongated and span the entire thickness of the neuroepithelium. As cells round up in preparation for mitosis, they sever their contacts with the basement membrane, but retain their apical junctions. Meanwhile, microtubules lose their apico‐basal orientation and the apical microfilament bundle relaxes to allow broadening of the luminal surface. These changes in the cytoarchitecture together with an increased cytoplasmic viscosity may cause rounding of mitotic cells and their juxtaluminal position. Mitotic cells remain at the lumen from late prophase through early telophase. By late telophase, daughter cells start to elongate toward the base of the neuroepithelium. The ultrastructural changes during elongation recapitulate, in a reverse order, the events of rounding up in preparation for mitosis. Daughter cells are connected for some time after mitosis by a thread of cytoplasm. The thread is filled with microtubules representing a remnant of the spindle complex and has an electron‐dense midbody at about the middle of its length. During the final stage of separation of daughter cells, the thread is split at the level of the midbody.
Calcium‐induced Dehiscence of Cortical Granules in Xenopus laevis Oocytes
Authors: Hollinger T. G. , Dumont James N. , Wallace R. A. 
Published: June 2005

AbstractMicroinjection of 0.1 μg of Ca++ into Xenopus laevis oocytes induces breakdown of the cortical granules. The cortical granules disappeared in both full grown (Stage VI) and small growing (Stage IV) oocytes. Microinjection of Mg++, K+, or Na+ had no effect on cortical granules in either Stage IV or Stage VI oocytes. Small quantities (0.03 μg) of Ca++ induced dehiscence of the cortical granules only in proximity to the injection site.
Production of tetraploid and homozygous diploid amphibians by suppression of first cleavage
Authors: Reinschmidt Dana C. , Simon Stuart J. , Volpe E. Peter , Tompkins Robert 
Published: June 2005

AbstractTetraploid and genetically homozygous diploid Xenopus can be produced conveniently, in large numbers, by suppressing the first cleavage division of eggs through the application of hydrostatic pressure. The pressure‐induced disruption of the mitotic spindle during the first division of a diploid zygote of the African clawed toad results in a tetraploid embryo. A homozygous diploid embryo can be derived by inhibiting the first cleavage of a parthenogenetically activated haploid egg. Both tetraploid and homozygous diploid larvae are viable and successfully undergo metamorphosis.
Identification of luteinizing hormone‐releasing hormone (LH‐RH) in the brain and pituitary gland of a fish by immunocytochemistry
Authors: Schreibman M. P. , Halpern L. R. , Th. Goos H. J. , Margolis‐Kazan H. 
Published: June 2005

AbstractFor the first time immunoreactive luteinizing hormone‐releasing hormone (LH‐RH) is demonstrated in both the brain and pituitary gland of a teleost (Xiphophorus maculatus) using an immunoperoxidase procedure. It is specifically localized in the perikarya and their axons of the ventral telencephalon and nucleus lateralis tuberis and within and between the gonadotrops and within some cells of the pars intermedia. These immuno‐reactions are extinguished when antiserum to LH‐RH is preincubated with LH‐RH antigen but not with neurohypophysial hormones.
Ontogenetic changes in water‐vapor conductance of eggs of yellow‐headed blackbirds (Xanthocephalus xanthocephalus)
Authors: Hanka Ladislav R. , Packard Gary C. , Sotherland Paul R. , Taigen Theodore L. , Boardman Thomas J. , Packard Mary J. 
Published: June 2005

AbstractEggs of Yellow‐headed Blackbirds were incubated in a forceddraft incubator, and conductance of eggs to water vapor was determined for eggs having undergone different amounts of development. Multiple regression analysis indicated that water‐vapor conductance is related to incubation time (expressed in both linear and quadratic forms) and to the length of pores through eggshells. Studies of geographic variation in conductance within a single avian species may be subject to serious sampling error if the eggs are at different stages of incubation at the time they are collected for study. Also, pore length is a better approximation to length of the diffusion pathway through an eggshell than is shell thickness.
Post‐exercise acid‐base disturbance in Gecarcinus lateralis, a Terrestrial Crab
Authors: Smatresk N. J. , Preslar A. J. , Cameron J. N. 
Published: June 2005

AbstractFollowing enforced activity the hemolymph of Gecarcinus lateralis exhibits a “mixed” respiratory and metabolic acidosis. There is an elevation of hemolymph lactate and P levels and a reduction of total CO2. The lactate release is slow and peak concentrations are reached in 20 minutes. One hour after exercise hemolymph pH, total CO2 and P have returned to resting levels but lactate is elevated for four hours following activity. The metabolic acidosis is due only partly to lactate. A rapid change in base deficit following exercise appears to be independent of lactate concentrations.
Regulation of corticotype through kinety insertion in Tetrahymena
Authors: Nelsen E. Marlo , Frankel Joseph 
Published: June 2005

AbstractInsertion of a new ciliary row (kinety) has been documented in cells of Tetrahymena thermophila subjected to certain nutritional shift‐down conditions. Under these conditions cells replace their oral structures and become rapid‐swimming, dispersal forms. During the oral replacement process cells with 18 or 19 kineties frequently add a kinety to express a corticotype (kinety number) of 19 or 20. Cells of corticotypes 20 or 21 do not change corticotype under these conditions. When cells undergo oral replacement upon entering stationary phase in nutrient medium, no increase in corticotype takes place even when the initial corticotype is 18 or 19. The increase in corticotype thus depends on the occurrence of oral replacement, the initial corticotype, and the nutritional shift‐down.Examination of cells stained with protein‐silver indicates that a new kinety is inserted near the conclusion of the oral replacement process in a postoral position, between the two pre‐existing postoral kineties (1 and n). The process appears to involve the insertion of basal body couplets derived from the newlyformed undulating membrane. This process forms a third postoral kinety. One of the original postoral kineties (n) is eventually extended to the anterior end of the cell to the left of the new oral apparatus.The present findings suggest that cortical stability characteristics are likely to be different under natural conditions, which are likely to involve periodic starvation, than they are under continuous cultivation in axenic nutrient media in the laboratory. It is predicted that under natural conditions a unique stability center near corticotype 20 will be manifested.
The effects of environmental oxygen levels on the respiratory function of hemocyanin in the crabs, Libinia emarginata and Ocypode quadrata
Authors: Burnett Louis E. 
Published: June 2005

AbstractThe respiratory function of the hemocyanin (Hcy)‐containing blood in the aquatic spider crab, Libinia emarginata, and the terrestrial ghost crab, Ocypode guadrata, was studied in animals exposed to normoxic and hypoxic conditions a t 25°C. In L. emarginata low concentrations of Hcy, although 90% O2, saturated at the gill, necessitate a high blood and water convection strategy. O. quadrata has blood with a higher concentration of hemocyanin which is 96% O2 saturated at the gill, obviating a very high rate of blood circulation. During progressive hypoxia convection initially increases on both sides of the gill in L. emarginata while in O. quadrata cardiac output decreases. Blood pH increases with decreasing ambient P, below 60 torr in L. emarginata, inducing a greater hemocyanin O2 affinity.
The effect of temperature on the male reproductive system of the common water snake (Nerodia sipedon)
Authors: Weil Michael R. , Aldridge Robert D. 
Published: June 2005

AbstractThe effect of various temperatures upon the male reproductive cycle of the common water snake (Nerodia sipedon) was studied. Snakes were divided into five groups and kept at five different temperature regimes and a 0L:24D photoperiod for ten weeks. Those kept in Chamber 1 were at 20°C the entire day while those kept in Chambers 2–5 were maintained at 21.3, 23.3, 27.4 and 29.3°C for eight hours per day respectively and 20°C for the remaining 16 hours each day.Interstitial cell nuclear diameters, renal sexual segment tubule diameters and epithelial heights were found to be unrelated to increasing temperatures. Testicular growth was positively correlated to increasing temperatures. Seminiferous tubule diameters increased rapidly between 20 and 21.3°C with a Q10 = 39. Tubule diameters continued to increase, although at a slower rate, with further increases in temperature, with a Q10 = 1.72 between 21.3 and 29.3°C. Spermatogenesis increased with increasing temperatures; the threshold temperature for initiation of spermatogenesis was between 20 and 21°C.Therefore, spermatogenesis and testicular recrudescence in Nerodia sipedon are temperature and not light dependent. Further, this report shows that weight of fat bodies does not affect normal spermatogenesis and testis growth in the presence of a sufficient food supply.
Polyspermy‐preventing mechanisms in mouse eggs fertilized in vitro
Authors: Sato Kodo 
Published: June 2005

AbstractThe time sequence of the mechanisms that prevent polyspermy in cumulus‐free mouse eggs was determined by continuous microscopic observations during in vitro fertilization. The zona reaction had begun, and the vitelline surface block to polyspermy was established, in less than one minute following sperm fusion with the vitellus. In less than five minutes, the zona reaction had advanced to the stage that no more spermatozoa could become firmly attached to the surface of the zona pellucida.
Composition of a protein antifreeze from larvae of the beetle, Tenebrio molitor
Authors: Patterson Jean L. , Duman John G. 
Published: June 2005

AbstractA thermal hysteresis producing antifreeze protein was isolated from larvae of the beetle, Tenebrio molitor. This is the first thermal hysteresis protein purified from an insect. The specific activity of the Tenebrio antifreeze is somewhat greater than that of the fishes. The composition of the Tenebrio protein is quite different from those of the fish protein antifreezes. The most obvious difference is the lack of a large alanine component in the Tenebrio antifreeze. The significance of the differences are discussed.
Beat frequency is bimodally distributed in spermatozoa from T/t12 mice
Authors: Katz David F. , Erickson Robert P. , Nathanson Michael 
Published: June 2005

AbstractFlagellar beat frequencies of spermatozoa from mice of varying genotype were studied using highspeed cinemicrography. Beat frequency was variable but unimodal in two inbred lines, their F1, and an outbred line. In contrast, beat frequency in spermatozoa from T‐complex, balanced lethal stocks (T/t6 and T/t12) tended not to vary between individual males of each genotype up to four hours after collection. The two‐hour distribution of beat frequency for T/t12 was, moreover, bimodal, suggesting the possible existence of two subpopulations of spermatozoa.
Toxicity to fish, effect on gill ATPase and gill ultrastructural changes induced by Pardachirus secretion and its derived toxin pardaxin
Authors: Primor Naftali , Sabnay Ilana , Lavie Vered , Zlotkin Eliahu 
Published: June 2005

AbstractThe ichthyotoxic mechanism of the Red Sea flatfish Pardachirus marmoratus crude secretion (PMC) and its derived toxin pardaxin was investigated using in vivo lethality tests and in vitro gill preparations of fish preadapted to different salinities. Comparative studies with ouabain and cytotoxin (a factor derived from cobra snake venom) were performed and it has been found that: 1) The lethal potencies of PMC increased in fish adapted to salinities above and below the isotonic level. 2) In contrast to PMC and pardaxin the lethal effects of ouabain and cytotoxin were weak upon external application and potent by injection. 3) When compared to ouabain, pardaxin was found to be about three and five orders of magnitude more potent gill ATPase inhibitor in fish and crustacean preparations, respectively. 4) EM studies of gills obtained from fish treated by sublethal doses of PMC revealed the appearance of apical crypts in gill chloride cells.
Seasonal variation of antifreeze peptide in the winter flounder, Pseudopleuronectes americanus
Authors: Petzel David H. , Reisman Howard M. , Devries Arthur L. 
Published: June 2005

AbstractSerum ion concentrations, freezing and melting points were determined for the winter flounder, Pseudopleuronectes americanus collected from Shinnecock Bay, Long Island over the course of one year. Melting points and ion concentrations showed little variation, however freezing points decreased to a low of −1.7°C during the winter. Serum freezing points‐melting points were used as estimates of the amount of antifreeze peptide present in each monthly sample. Antifreeze peptide levels were highest (25 mg/ml serum) during the winter and less than 1 mg/ml during the summer.A comparison of the concentrations of antifreeze peptide present in flounder from Shinnecock Bay with concentrations reported in flounder from Conception Bay, Newfoundland showed that both populations synthesize their antifreezes at the same time despite differences in temperature and photoperiod. However flounder from Conception Bay retain higher concentrations during the spring, presumably because of the lower water temperatures there.
The quantitative role of haemocyanin in the respiration of abalone (genus Haliotis)
Authors: Ainslie Robert C. 
Published: June 2005

AbstractThe bloods of the gastropod molluscs Haliotis ruber, H. laevigata, and H. roei deliver respectively 0.56 vol %, 0.62 vol %, and 0.90 vol % of oxygen to the tissues per circulatory cycle at the acclimation temperature 20°C. In each case over 80% of the oxygen delivered is bound to the haemocyanin. The greater amount of oxygen delivered by the blood of H. roei results primarily from the consistently higher haemocyanin concentration, hence oxygen carrying capacity, of the blood of, this species. It is hypothesized that this may be advantageous to this mobile, active abalone species by reducing the load on the circulatory system in maintaining respiration during activity.Following an abrupt temperature increase from 20°C–25°C the oxygen delivered by the blood to the tissues per circulatory cycle decreases in all species, the most marked decrease being in H. roei which only delivers 67% of the 20°C value. In each case however, over 80% of the total delivered oxygen is still carried by the haemocyanin. Owing to the large oxygen carrying capacity of H. roei haemocyanin, the absolute amount of oxygen delivered per cycle is still larger than that in theother two species. A large reverse Bohr effect is apparent in all species at both temperatures, but its importance to the abalone is not clear when their mode of existence is considered.
Trochlear nerve regeneration in Xenopus laevis larvae
Authors: Fangboner Raymond F. , Luncsford Amelita P. , Vanable Joseph W. 
Published: June 2005

AbstractThe trochlear nerve of Xenopus laevis larvae was sectioned in the orbit, and the nerve distal to the section was removed, so that it could not serve to guide the return of the regenerating nerve to the superior oblique muscle (SOM). In a second series, in addition to removing the distal nerve segment, the SOM was removed or damaged. The regeneration pattern of the trochlear nerve fibers was recorded in situ at 1 to 5‐day intervals with the aid of methylene blue staining. The early growth ofregenerating fibers was multidirectional; only some fibers encountered the SOM by day 6 or 7; others reached nerves, inappropriate muscle, and other tissues. Ultimately, the fibers that reached the SOM persisted and were reinforced, while those that reached other locations were withdrawn. By 20 days or so, the regenerated trochlear nerve usually had an appearance that was close to that of an uncut nerve. In the second series, in which the SOM was removed or damaged, the multidirectional character of the growth persisted through 20 days after section. These data suggest that: 1) Trochlear nerve regeneration is not guided by cues that closely control fiber growth along a direct path to the SOM, and 2) The SOM acts as a trap for regenerating trochlear nerve fibers, promoting the maintenance and the fasciculation of the trochlear nerve fibers that reach it, and the degeneration of the fibers that do not.
A fast‐oxidative crustacean muscle: Histochemical comparison with other crustacean muscle
Authors: Silverman Harold , Charlton Milton P. 
Published: June 2005

AbstractThe present study describes a fast contracting, fatigue resistant, highly oxidative muscle found in the mouth parts of decapod crustaceans. The muscle studied was isolated from the blue crab, Callinectes sapidus. Histochemical techniques modified from those commonly used in mammalian striated muscle fiber typing were used to facilitate comparison of this fast‐oxidative muscle with other crustacean muscle. Comparison was made between this muscle and the slower cheliped opener muscle and the levator muscle of the fifth periopod. Differences in both SDH activity and myofibrillar ATPase activity between these muscles are described. The advantages and the difficulties involved in interpreting the histochemical reactions of various crustacean muscle fibers are also reviewed.
The symbiotic association between intracellular zoochlorellae (chlorophyceae) and the coelenterate Anthopleura xanthogrammica
Authors: O'Brien Timothy L. 
Published: June 2005

AbstractThe ability of intracellular marine zoochlorellae (Chlorophyceae) to provide their host with photosynthetically fixed carbon in vivo or with algal by‐products via hetrophagy or autophagy is examined in the coelenterate A nthopleura xanthogrammica. Algae do fix 14CO2 within the gastrodermal tissue layer of the host and the level of 14C present within the gastrodermis is dependent upon the nutritional state of the host. The various techniques used to detect the percent light‐fixed 14C present within the tissues of the host result in values ranging from less than zero to 3.9%, independent of the nutritional state of the host, indicating that relatively small amounts of soluble fixed carbon are translocatedto, the host's tissues. Acid phosphatase reaction product is absent within vacuoles containing algae; cellular debris which co‐occurs within these same vacuoles is also free of reaction product, suggesting that the presence of an alga within a vacuole inhibits (in an unknown manner) the cellular digestive processes of the host. Further, reaction product is restricted to the exterior of the cell wall following expulsion of algae into the host's coelenteron, suggesting that the cell wall is resistant tolysosomal hydrolase activity. The distribution of acid phosphatase reaction product in situ suggests that little in the way of algal by‐products would be made available to the host by the process of heterophagy or autophagy.
Action spectrum for ultraviolet irradiation inactivation of a cytoplasmic component(s) required for neural induction in the amphibian egg
Authors: Youn B. Woo , Malacinski George M. 
Published: June 2005

AbstractAn action spectrum was established for the destruction by ultraviolet radiation of cytoplasmic components of the neural induction system in the eggs of the South African clawed frog, Xenopus laevis. The action spectrum showed a peak at 280 nm and a decline towards both 250 nm and 320 nm after quantum corrections were made. These results are compatible with the assumption that proteins are involved in the initial photoreaction.
Induction of triploidy in Xenopus laevis by heat shocking of the egg before and after fertilization
Authors: Cassidy Donna M. , Blackler Antonie W. 
Published: June 2005

AbstractEggs of the frog Xenopus laevis have been subjected to a temperature shock before or after fertilization. The shock provokes triploidy through suppression of elimination of the second polar body; application of the shock within ten minutes of fertilization was associated with triploid frequencies to 90%. All series in which eggs were shocked after fertilization manifested some abnormal development in the surviving eggs, the greatest abnormality frequency correlated with the period of greatest sensitivity for the induction of triploidy. Up to 50% triploidy was induced in the eggs of certain females when the temperature shock was applied before fertilization. In these series, the capacity for normal development was not appreciably lowered by the treatment. A comparison is made between thermal and pressure techniques for the induction of triploidy.