bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degeneration and regeneration in abdominal flexor motor neurons in the crayfish
Authors: Hoy Ronald R. 
Published: June 2005

AbstractElectrophysiological studies of sectioned crayfish motor axons of the abdominal flexor muscle have demonstrated that the distal stumps, isolated from their central connections for up to several months, are remarkably resistant to degeneration, as previously shown in the crayfish claw opener preparation. These distal stumps remained electrically excitable and intracellular recording showed that their neuromuscular junctional properties were indistinguishable from normal ones in such properties as waveform and amplitudes of the evoked junctional potentials. Furthermore, repetitive stimulation of the distal stumps evoked jp's which showed facilitation as in normal preparations. When degeneration finally occurred, electrical stimulation of the nerve no longer evoked jp's, and no progressive deterioration of junctional properties was observed.Regeneration ultimately occurred in these nerves but required at least three weeks or more. The electrical properties of these regenerated junctions were not different from normal ones.The evidence from time‐course and correlated histological studies of degeneration and regeneration suggest that regeneration of these crayfish nerves occurs by axonal fusion rather than by outgrowth of an entirely new distal apparatus from centrally located cell bodies, as is the mechanism in vertebrates and some invertebrates.
Physiological studies on supercooled killifish (Fundulus heteroclitus) I. Serum inorganic constituents in relation to osmotic and ionic regulation at subzero temperatures
Authors: Umminger Bruce L. 
Published: June 2005

AbstractPhysiochemical properties (serum osmolality and blood pH), serum inorganic ions (sodium, potassium, calcium, magnesium, chloride, phosphate and bicarbonate) and tissue water were studied in parallel groups of adult male Fundulus heteroclitus acclimated to various temperatures (30°C, 20°C, 10°C, 4°C, 2°C, −1°C and −1.5°C) in salt water under otherwise constant laboratory conditions. When the acclimation temperature was lowered from 20°C to −1.5°C, serum osmolality increased by 20%. This increase was not indicative of osmoregulatory failure, however, since the proportion of total serum osmolality accounted for by inorganic electrolytes dropped from 98% at 20°C to 93% at −1.5°C. Serum electrolytes such as sodium, chloride, calcium, magnesium and bicarbonate increased in the subzero cold by 12%, 17%, 30%, 33% and 11% respectively whereas serum potassium and inorganic phosphate levels were unchanged. Blood pH was significantly higher at 10°C than at any other temperature. The water content of liver, testes and muscle decreased by 8% in the subzero cold. These changes in serum electrolytes and tissue water did not indicate osmoregulatory failure, however, since the new levels, once established, were maintained as long as the fish were alive. Although osmotic and ionic regulation were not as effective in the cold, they were by no means so poor as to cause death by osmotic imbalance.
Environmental control of annual testicular cycles in the lizard Anolis carolinensis. III. Temperature thresholds for photoperiodism
Authors: Licht Paul 
Published: June 2005

AbstractPhoto‐sexual responses in Anolis carolinensis during the fall are highly temperature dependent and show distinct thermal thresholds. If body temperatures are maintained at 32°C (the species' preferred temperature), day lengths of 13 hours or more stimulate testicular growth, whereas day lengths of 12 hours or less inhibit recrudescence. The testis develops slowly and independently of day length at 25°C or below. With fluctuating body temperatures, photoperiodism depends on both the duration of daily heating to 32°C (the thermoperiod) and the level of nocturnal cooling. Photo‐sexual responses occur with thermoperiods of eight hours or more when the nocturnal temperature is 20°C, but longer thermoperiods are required if nocturnal temperatures are reduced. There may be some equivalence between heat and light with regard to photo‐sexual responses; the critical day length for photostimulation varies with temperature.Field observations of behavioral thermoregulation and climatic data for the lizards' habitat (around New Orleans, Louisiana) indicate that body temperatures are high enough to allow photoperiodism in September. Since the effective day length is 12 hours or less, testicular growth may be photoperiodically inhibited in September and early October. The natural onset of testicular growth in mid‐October may be due to a reduction of thermoperiod and nocturnal temperatures which abolishes the photo‐periodic responsiveness and to an inherent reduction in photosensitivity.Studies begun in January confirm that the completion of testicular recrudescence in the spring is determined largely by the elevation of body temperatures and is independent of day length. Testicular development is rapidly completed with only a few hours of daily heating to preferred levels (32°C) even if nights are cold (e.g., 12°C).
Effects of estrogen, SU‐9055, and cyproterone acetate on the hypersecretory activity in the seminal vesicles of the castrate catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Nayyar S. K. 
Published: June 2005

AbstractThe effect of estradiol benzoate (EB), SU‐9055, and cyproterone acetate (CA) on the hypersecretory seminal vesicles of the castrate catfish has been studied. EB to a marked extent, SU‐9055 and CA to a lesser extent inhibit castration induced hypersecretion in the seminal vesicles. This implies that while EB inhibits the gonadotrophin production, SU‐9055 and CA act at the level of the interrenal glands and the seminal vesicles respectively. The data indicate that following castration the high level of circulating gonadotrophin induces the interrenals to produce androgens which in turn bring about hypersecretion in the seminal vesicles.
The mesoglea of hydra. III. Fiber system changes in morphogenesis
Authors: Hausman Robert E. , Burnett Allison L. 
Published: June 2005

AbstractExamination of isolated mesogleas of Hydra pseudoligactis demonstrates that the organization of the collagen‐elastin‐like fiber system is dependent on the morphogenic state of the animal. There is a fiber system change associated with each of the three morphogenic capabilities of the animal: budding regeneration, and body column growth.Non‐budding animals maintain a complete oral‐aboral fiber system throughout the body column. Hydra in the early stages of budding exhibit an organized fiber system in the peduncle only. Hydra maintained as continuously budding do not reorganize the mesogleal fiber pattern. The molecular or macromolecular changes in the fiber system are not, as yet, known.Fiber system changes experimentally induced by feeding or hypostome excision appear the same as the breakdown associated with budding but differ in their extent through the animal. The observed changes are related to the different morphogenic capabilities of Hydra through a theory of cell migration and cell adhesion.
Chloride‐cell and mucus cell response to chloride and sulphate‐enriched media in the gills of Gambusia affinis affinis (Barid and Girard) and Catla catla (Hamilton)
Authors: Ahuja Surender K. 
Published: June 2005

AbstractComparative response of “chloride‐cell” and mucus cell to chloride‐and sulphate‐enriched media in the gill of Gambusia and Catla was studied. The presence of a large number of “chloride‐secretory cells” and their significant hypertrophy are correlated with the high tolerance of Gambusia to chloride media. The functional difference of phospholipids and mitochondria in the “chloride‐cells” between active and dying Gambusia is described. Mucus cells normally present in freshwater Gambusia, are not observed in the gills of active, salt‐adapting fishes beyond 2.7% salinity. Reappearance of these cells in a small number in the gills of non‐adapting and dying Gambusia at high chloride salinities may represent stages of “chloride‐cell” transformation into the mucus type. At high sulphate salinities the “chloride‐cells” become functional as is evidenced by increase in cell‐size under conditions of extreme kidney degeneration. Results suggest that “chloride‐cells” may not excrete bivalent ions in Gambusia adapting to comparatively low concentrations (0.57–1.81%) of sulphate media. Mucus cells are observed at all concentrations of sulphate media containing no chlorides.Absence of “chloride‐secretory cells” in the gill of Catla is correlated with their low tolerance to chloride media. Mucus cells normally present in a large number in freshwater Catla are completely absent in fishes acclimatized to 1.1 to 1.5% chloride media. These cells show a partial atrophy in sulphate media containing a proportionately small quantity of chlorides. The physiological significance of the presence or absence of “chloride‐secretory cells” is discussed in relation to the tolerance of euryhaline and stenohaline teleostean species to univalent and bivalent ions.
Thymidine kinase activity during regeneration in the planarian Dugesia dorotocephala
Authors: Coward S. J. , Hirsh F. M. , Taylor J. H. 
Published: June 2005

AbstractThymidine kinase (TdR kinase) activity has been measured at various stages of regeneration in the planarian Dugesia dorotocephala. It is argued that TdR kinase activity is a valid, indirect measurement of cell proliferation in this organism. The earliest measured responses to wounding and the initiation of regeneration show maximal TdR kinase activities in non‐blastema regions. Later phases of regeneration show a shift of maxima to the blastemata with the general relations: prospective head blastemata have higher activity than prospective tail balstemata and posterior blastemata lag behind more anterior blastemata of the same developmental fate. It is concluded that the earliest proliferative response to wounding is in non‐blastema regions with secondary waves of proliferation in the blastemata proceding differentiation. The data are consistent both with models invoking long‐range cell migration and with models of local origin of the blastemata. Hydroxyurea treatment increases the level of TdR kinase activity and at low concentrations causes a modest acceleration in the rate of regeneration. Hydroxyurea treatment also produces bipolar (hetermorphic) regenerants from posteriorly‐derived sections. The possible role of cell number is invoked in relation to bipolar forms and as a regulator of normal differentiation.
Androgenic and male‐inducing effects of 11‐ketotestosterone on a teleost, the medaka (Oryzias latipes)
Authors: Hishida Tomi‐O , Kawamoto Noriko 
Published: June 2005

AbstractThe androgenic and the male‐inducing (androtermonic) activities of 11‐ketotestosterone were evaluated respectively by its abilities to stimulate a secondary sex character and to reverse gonadal sex differentiation in a teleost, the medaka (Oryzias latipes). The median effective dose (ED 50) of this steriod necessary to induce the formation of papillar process on the anal fin was 37 μg/g of food. The androgen is therefore about 8 times potent than testosterone propionate and 17 times more potent than pure testosterone in the same test. The ED 50 for androtermonic activity (reversal of genetic females to phenotypic males) was found to be about 110 μg/g of food. Compared with testosterone propionate the 11‐keto compound is about five times more potent. Thus, in teleosts, 11‐ketotestosterone appears to be the most potent androgen of vertebrate origin for both androgenic and androtermonic potencies. The ratio of androtermonic to androgenic potencies (ED 50s) for 11‐ketotestosterone is 3.0.
Recuperation of regeneration in denervated limbs of Ambystoma larvae
Authors: Thornton Charles S. , Thornton Mary T. 
Published: June 2005

AbstractThe current neurotrophic theory of amphibian limb regeneration allows for a non‐neural tissue contribution of trophic substance (TS) which during ontogeny is suppressed by the production of large amounts of neural TS. A difficulty has been to account for the inability of denervated limbs to initiate regeneration in the absence of neural TS when non‐neural tissue TS synthesis, no longer “quenched,” might be expected to function. This difficulty has now been overcome in the aneurogenic limb system. Aneurogenic forelimbs of A. maculatum larvae were transplanted orthotopically and homoplastically in place of left forelimbs of normally innervated larvae. The brachial nerves of the host larva were allowed to grow into the grafted aneurogenic limb. When tested by subsequent denervation and amputation, the grafted limbs became progressively nerve‐dependent, for regeneration purposes, between 10 and 13 days post‐transplantation, dependence on nerves being complete at 13 days. Grafted, aneurogenic limbs were allowed to become innervated for periods of 2–3 weeks. Then for at least 30 days the limbs were maintained in a nerveless state by denervations, repeated at five day intervals, with histological checks on effectiveness of denervation. Amputation through the forearm was performed at 30 days with continued denervations to prevent reinnervation. Regeneration occurred in 49% of cases (in 16 of 33 limbs) with histological verification of nerveless or sparsely innervated condition. Thus, regeneration‐competent aneurogenic limbs may become nerve‐dependent after transplantation and then, after prolonged denervation, recover ability to regenerate under essentially nerveless conditions.
Regeneration in the African lungfish, Protopterus. I. Gross aspects
Authors: Conant Elizabeth Babbott 
Published: June 2005

AbstractThe regeneration of appendages of Protopterus annectens and P. aethiopicus has been studied. Both limbs and tail demonstrate a notable capacity for self‐replacement. The initial direction of growth in the regenerate depended upon the nature of the amputation plane: straight, pointed, or terminally notched cuts elicited new growth along the primary axis, whereas cuts made at an angle resulted in regenerates whose axis was perpendicular to the plane of cut. In these cases, differential growth ultimately compensated and the final form was consistent with the axis of the original appendage. Lateral notches made in the posterior margin of the pectoral limb may effect the growth of a secondary filament. Such bifidism could not be elicited from pelvic limbs or tails.Growth curves showed a lag period of up to three and one‐half weeks, a period of rapid growth lasting one or more months, and then a time of decelerating growth. For each individual fish, these phases were undergone simultaneously, regardless of appendage, direction of cut, or amputation level. Limbs cut proximally, however, showed greater and more rapid growth than those with less material removed. Total replacement was found in all but some pelvic limbs.Regeneration, if in the lag phase, was halted by estivation, but rapid growth commenced shortly after arousal.Comparisons are made with other vertebrates.
Phototactic orientation by the marine dinoflagellate Gyrodinium dorsum Kofoid. I. A mechanism model
Authors: Hand William G. 
Published: June 2005

AbstractPhototatic orientation by the marine dinoflagellate Gyrodinium dorsum was examined using closed circuit television methods. Mono‐ and bi‐directional stimuli were used to determine directional discrimination by the cells. Cell orientation time was also measured. From the results obtained, a model is presented which proposes paired photoreceptor sites.
Effects of low environmental pH on blood pH and sodium balance of brook trout
Authors: Packer Randall K. , Dunson William A. 
Published: June 2005

AbstractBrook trout (Salvelinus fontinales) exposed to a low environmental pH (3.0–3.3) showed a drop in mean blood pH from 7.39 to 6.97. Trout at an environmental pH of 3.5 lost 50% of their total body sodium. Control sodium influx (72.5 μmoles/100 g hours) decreased to zero between pH 3.0 and 4.9 as Na efflux increased markedly over control levels. There was no significant difference in body Na content of wild trout from three streams ranging in pH from 6.05 to 7.10. Trout survived 13.1 to 14.7 hours in a 150 mM Na solution of pH 3.5 as compared to 2.5 to 4.9 hours at 100 μM Na and the same pH. The inability of brook trout to live in waters of pH less than about five, seems to be related to a drop in blood pH caused by the high hydrogen ion concentration of the medium. The loss of body Na appears to be of secondary importance as a cause of death.
The effect of nerve growth factor on limb regeneration in Ambystoma
Authors: Weis Judith S. , Weis Peddrick 
Published: June 2005

AbstractYoung Ambystoma larvae were subjected to forelimb amputation followed by a series of injections of either nerve growth factor (NGF) or saline solution. The animals receiving the NGF injections showed an increase in the length of the regenerate and an acceleration of digit formation at times up to two weeks after amputation. The maximum per cent increase in length occurred at about nine days post‐amputation. By two weeks after amputation, however, the difference between NGF‐treated and control animals had diminished considerably. The nerve growth factor, by increasing the extent of sensory innervation to the stump apparently accelerated blastema formation and early stages of regeneration. The fact that the regenerative rate can be altered by changing the nerve supply implies that there is not an absolute neural threshold for regeneration. Striking differences were noted in the normal regenerative rate of A. opacum as compared with A. maculatum.
Cytological observations on sperm penetration of rabbit eggs
Authors: Harper M. J. K. 
Published: June 2005

AbstractPhotomicrographs of the cytological changes of the sperm head and of the female chromatin in the rabbit egg, from the time of sperm penetration and activation of the second meiotic metaphase up to the formation of pronuclei and syngamy, are presented. During a study on factors affecting sperm penetration of rabbit eggs, some anomalous eggs were observed. One unfertilized egg possessed two second meiotic metaphases and associated first polar bodies, while another similar egg had two first and two second polar bodies, two sets of female chromatin, and one fertilizing sperm. In this latter egg fertilization was apparently proceeding normally. Two eggs within a single zona pellucida were also seen; one of these was a primary oocyte, while the other was a normally penetrated egg. Evidence is also presented which indicates that the incidence of polyspermy (usually dispermy) is increased, if eggs enter the oviduct at 14 hours or later after mating. This is thought to be due to more fully capacitated sperm present at the site of fertilization at these later times, and thus there is a greater chance of two or more sperm entering the vitellus at the same time.
An analysis of the development of conjunctival papillae and scleral ossicles in the eye of the scaleless mutant,
Authors: Palmoski M. J. , Goetinck P. F. 
Published: June 2005

AbstractAn analysis was carried out on the number and location of conjunctival papillae and scleral ossicles in chick embryos homozygous for the recessive gene scaleless. There are, on the average, three conjunctival papillae per eye in the mutant, while normal embryos have 14. The mutant is also deficient in the number of scleral ossicles having an average of one ossicle per eye. The ossicles of scaleless mutants in contrast to normals, are variable in size and irregular in shape. They are found in the same region as the papillae which remain after nine days of incubation. Histological examinations indicate a general retardation of the scaleless conjunctival papillae.
Effect of gonadotropins and testosterone on the initiation of spermatogenesis in the hypophysectomised Indian house lizard, Hemidactylus flaviviridis Ruppell
Authors: Reddy P. R. K. , Prasad M. R. N. 
Published: June 2005

AbstractThe action of gonadotropins (FSH, LH, PMS, and HCG) and testosterone on the initiation of spermatogenesis was studied in the Indian House Lizard Hemidactylus during the non‐breeding season after pituitary ablation. Both ovine FSH and PMS initiated spermatogenesis leading to the formation of mature spermatozoa after 45 days while LH, HCG, or TP had no stimulatory effect on the testis. Synergistic action was not observed when FSH or PMS was injected in combination with LH, TP, or HCG as evidenced by the germ cell counts in the seminiferous tubules.The androgen‐dependent sexual segment of the kidney was also fully developed in the animals treated with FSH or PMS. These results indicate that the initiation of gametogenic and androgenic functions in the testis of the Indian house lizard are dependent on an FSH‐like protein.
Electromechanical coupling in a molluscan muscle, the radula protractor of Busycon canaliculatum
Authors: Hill Robert B. , Greenberg Michael J. , Irisawa Hiroshi , Nomura Hiromichi 
Published: June 2005

AbstractThe radula protractor can be made to be spontaneously rhythmic, although it is normally a quiescent, phasic muscle, with apparently multi‐unit organization. Acetylcholine and potassium depolarize with contracture. Once a radula muscle has been put into a long‐lasting contracture by acetylcholine, tryptamine can repolarize it with accompanying relaxation. In the continued presence of acetylcholine and tryptamine, the repolarization and relaxation gradually taper off while membrane oscillation accompanied by mechanical rhythmicity develops. Contrariwise, if a radula protractor is in a potassium contracture, tryptamine will potentiate the contracture without affecting the level of membrane depolarization. Potentiation of potassium contracture, without changing potential level, can also be effected by increased calcium concentrations or by caffeine. After a muscle has been soaked in artificial sea water lacking calcium, its twitch tension, tetanic tension, potassium contracture, and acetylcholine contracture become directly dependent on external calcium concentration.
On the measurement of cell adhesiveness
Authors: Gershman Howard 
Published: June 2005

AbstractFour parameters that might be related to either the cell surface or cell adhesiveness were examined as a function of embryonic age in chick cells, and compared to each other. The four parameters were: (1) size of aggregates formed in shaker culture; (2) rate of aggregation in shaker culture; (3) sorting‐out behavior; (4) surface charge density. Aggregate size and aggregation rate of retinal cells were both found to decrease from 5 to 19 days of embryonic development, but the decreases followed different patterns. Sorting‐out behavior remained constant from as early as four to as late as 19 days of development (liver, heart and retinal cells). Surface charge density of retinal cells at physiological pH's rose from five to seven days, reached a maximum value between 7 and 11 days, and decreased from 11 to 19 days of development. Because of this negative correlation, it was concluded that the four parameters reflect different properties of the cell surface.
Some kinetic aspects of sperm specific lactate dehydrogenase in mice
Authors: Hawtrey Christopher O. , Goldberg Erwin 
Published: June 2005

AbstractPurified LDH‐X, LDH‐1, and LDH‐5 isozymes from mouse tissues were compared according to several biochemical parameters. The sperm specific LDH‐X is more thermostable than the other isozymes, retaining 100% activity after 30 minutes at 65°C. Activity of LDH‐1 is reduced by 50% under these conditions while LDH‐5 is completely inactivated at this temperature within 18 minutes. The three isozymes had different Km values for both pyruvate and lactate with LDH‐X showing the highest substrate “affinities.” In addition, LDH‐X reacted significantly with both α‐hydroxy‐valerate and ketovalerate substrates. There was little or no catalytic activity of LDH‐X with other substrates, including several steroids, β‐hydroxybutyrate, α‐hydroxyisobutyrate, α‐ketoglutarate, α‐hydroxycaproate, and sorbitol.