bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sexual reproduction in the rotifer Asplanchna girodi: Effects of tocopherol and population density
Authors: Gilbert John J. , Litton James R. 
Published: June 2005

AbstractPopulations containing undetectable levels of tocopherol (< 6.78–20.83 ng per g dry weight rotifer) exhibited normal sexual reproduction, indicating that this species and probably also A. brightwelli and A. sieboldi, do not require tocopherol for male fertility. Thus, the hypothesis that tocopherol is an adaptive signal for mictic‐female production in these latter two species by virtue of its role in male fertility is no longer tenable.Dietary tocopherol had irregular and only slight, if any, effects on body size and shape, and it did not influence the level of mictic‐female production.Mictic‐female production was significantly but irregularly affected by population density, at least within the range of 0.0067 to 5 females per ml. No relationship between population density and level of mictic‐female production was observed. The laboratory results are compared with available data on the occurrence of sexuality in a natural population.None of the 4,537 offspring isolated from parental females in the population density experiments were amphoteric females. Thus, at least under those conditions, this type of female must be extremely rare.A. girodi differs greatly from A. brightwelli and A. sieboldi regarding responses to tocopherol and the control of sexual reproduction.
Hamster sperm cross react with antiactin
Authors: Talbot Prudence , Kleve Maurice G. 
Published: June 2005

AbstractHamster sperm extracts contain a polypeptide which comigrates with muscle actin on polyacrylamide gel electrophoresis. On double diffusion precipitation plates, sperm extracts form a single precipitin band with an antibody to muscle actin (antiactin) and show a reaction of identity with muscle actin. Indirect immunofluorescent microscopy revealed that antiactin binds along the concave margin and equatorial segment in the acrosomal region, in the connecting piece of the neck, and in the principal piece of the tail. These results are evidence that hamster sperm contain actin. The possible significance of these observations in fertilization is considered.
Collagen production by the free‐living nematode Panagrellus silusiae in the presence of the proline analogue L‐azetidine‐2‐carboxylic acid
Authors: Leushner J. , Pasternak J. 
Published: June 2005

AbstractThe effect of the proline analogue, L‐azetidine‐2‐carboxylic acid, on growth and collagen synthesis in the free‐living nematode Panagrellus silusiae was examined. Morph metrically, the worms showed no evidence of an adverse response to the long term presence of azetidine carboxylic acid (20 mM/ml) in the growth media. Incorporation of labelled proline into protein was specifically blocked by the analogue; whereas the uptake of radiolabel led leucine into polypeptides was unaffected. Conversely, the uptake of labelled azetidine carboxylate was antagonized only by proline. The incorporation of labelled analogue into collagen during postembryonic development paralleled the discontinuous pattern of collagen biosynthesis in untreated worms. Cuticular collagens became labelled after incubation with [14C]‐azetidine carboxylate. These results suggest that the analogue is incorporated into collagenous and noncollagenous proteins. To substantiate this point, amino acid analyses of cuticles that were isolated from azetidine carboxylate‐treated worms revealed that the analogue can replace at least 39% of the imino acid residues of the cuticular collagens. Thus, resistance to azetidine carboxylic acid in this organism is not due totally to the metabolic breakdown of the analogue. Although the extent to which noncollagenous proteins incorporate the analogue was not determined directly, it is likely that azetidine carboxylic acid is incorporated into diverse globular proteins without a complete loss of activity of the substituted molecules. Certainly, in the cuticular collagens the analogue can readily replace	prolyl residues without any apparent deleterious consequences.
Yolk proteins in the house cricket, Acheta domesticus: Identification, characterization, and effect of ovariectomy upon their synthesis
Authors: Bradley James T. , Edwards John S. 
Published: June 2005

AbstractFour female‐specific yolk proteins were identified in the hemolymph of adult, ovulating Acheta domesticus through the use of SDS‐polyacrylamide gel electrophoresis. Molecular weights were estimated at 130,000; 97,000; 49,000; and 47,000 daltons, and all four proteins stained PAS‐positive. None of the yolk proteins were detectable in the blood of males or immature females.The rapid appearance and accumulation of yolk proteins in the blood two to five days after adult ecdysis involves de novo synthesis of the proteins and is unaffected by ovariectomy or hemiovariectomy performed six to eight days prior to ecdysis. Although ovariectomy resulted in the accumulation of yolk proteins in the blood, a comparison of the specific activities of hemolymph proteins in ovariectomized, hemiovariectomized, and sham operated animals following 3H‐leucine injection suggest that the absence of ovarian tissue may lead to a reduction in the net rate of yolk protein synthesis.
Regenerative ability of double‐half and half upper arms in the newt, Notophthalmus viridescens
Authors: Bryant Susan V. , Baca Bruce A. 
Published: June 2005

AbstractThe upper arms of adult newts (Notophthalmus viridescens) were surgically manipulated to create double‐half dorsal, double‐half ventral, double‐half anterior, and double‐half posterior upper arms, and longitudinal half‐dorsal, half‐ventral, half‐anterior, and half‐posterior upper arms. Amputation through the double‐half upper arms usually failed to elicit normal distal regeneration, despite the fact that an apparently normal regeneration blastema was initially formed. Instead, regeneration in these cases was limited to the formation of a variable number of small cartilage elements. On the basis of these results it is concluded that a complete limb circumference is required for distal transformation in newts, in addition to the well‐established requirements for a wound epidermis, adequate innervation and dedifferentiation leading to blastema formation. A model for the sequential generation of new parts of the limb pattern during distal transformation from a complete circumference is presented. This model can also account for the occurrence of normal early stages of regeneration in double‐half upper arms.Half upper arms which were amputated immediately were shown to develop single, complete regenerates. If amputation of half upper arms was delayed three or more weeks to permit complete wound healing, a supernumerary limb from the lateral wound surface sometimes developed in addition to a complete, single limb from the distal amputation surface.
In vitro analysis of pre‐ and early postimplantation development of lethal yellow (Ay/Ay) mouse embryos
Authors: Johnson Linda L. , Granholm Nels H. 
Published: June 2005

AbstractPreimplantation embryos from matings between yellow heterozygous (Ay/a) mice were recovered at 56 hours post coitum, cultured for five days, and compared with the development of embryos from three control matings (Ay/a ♀ × a/a ♂, a/a ♀ × Ay/a ♂, a/a ♀ × a/a ♂). Most embryos were at the 8‐cell stage at recovery; however fewer embryos from the experimental cross had developed to the 8‐cell stage than embryos of control matings, indicating a developmental lag of experimental embryos (P < 0.01). The yellow (Ay/a) uterus did not contribute (P = 0.05) to delayed development. Experimental and control embryos were equally capable of successful development in culture to the morula stage with no distinct morphological characteristics identifying the class of Ay/Ay mutants. However, significant differences were observed in the development from morulae to blastocysts; 9.4% (10/106) of the morulae in experimental crosses failed to undergo blastocyst formation as compared with 2.5% (10/398) of morulae in pooled control crosses (P = 0.010–0.025). In the experimental cross 25.0% (24/96) of embryos that developed successfully to the blastocyst stage failed to hatch from the zona pellucida; these are presumed to include the class of lethal yellow homozygotes. Abnormalities seen in cultured embryos consisted primarily of blastomere disintegration, blastomere arrest and exclusion, and embryo fragmentation.
Studies on oocyte maturation of the medaka, Oryzias latipes V. On the structure of steroids that induce maturation in vitro
Authors: Iwamatsu Takashi 
Published: June 2005

AbstractThe response of oocytes within isolated follicles (800–950μ in diameter) to various steroids was examined with the teleost fish, Oryzias latipes. Continuous exposure of oocytes, which were removed from ovarian investments 17 hours before predicted germinal vesicle breakdown (GVBD), to C19‐ or C21‐steroids brought about maturation in vitro but never triggered ovulation. The steroids effective in inducing maturation have in common a C = O (or α‐OH) group at 3C and a β‐OH group at 17C in the C19‐steroids, and a C = 0 (or β‐OH) group at 3C and a C = O (or α‐OH) group at 20C in the C21‐steroids, in addition to an Δ4‐ or Δ5‐unsaturated or 5α‐saturated configuration. The orientation of the hydrogen at 5C seems to be critical in determining the ability of a particular steroid to stimulate oocyte maturation.Maturation of oocytes in the ovaries of hypophysectomized females was induced by administering progesterone, but the mature oocytes did not subsequently undergo ovulation. Thus the steroid hormone is capable of inducing oocyte maturation but apparently does not participate directly in the ovulation of Oryzias latipes oocytes.
Atrophy of a breast muscle with a single fibre type (M. pectoralis) in fasting willow grouse, Lagopus lagopus (L.)
Authors: Grammeltvedt R. 
Published: June 2005

AbstractThe willow grouse (Lagopus lagopus) are arctic gallinaceous birds with small fat stores and large muscles. In winter, these birds may starve for periods of several days. It was important to know which energy reserves were utilized during periods of starvation. Body composition of female willow grouse and Bantam hens was studied before and after fasting. Grouse have much larger breast muscles than do Bantams, but reproductive organs are larger in the hens. The relative amounts of adipose tissue are about equal in grouse and Bantams. When the birds had lost about 20% of their initial body weight due to fasting, Bantams had lost as much weight from their reproductive organs as from the adipose tissue, with little loss from the muscles. Grouse lost more weight from the pectoralis muscles alone than from the adipose tissue. Since the major component of muscle is protein, the grouse obtain a larger proportion of caloric needs during fasting from protein than do the Bantams.Grouse breast muscles are dark red, and the pectoralis consists homogeneously of type IIa (oxidative‐glycolytic) fibres, assessed by ATPase and by Sudan Black staining. The supracoracoideus muscle has type II fibres, not resolvable in subtypes. The leg muscle biceps femoris contains the three fibre types I, IIa, and IIb. During fasting, the weight loss of the pectoralis muscle may be accounted for by all fibres losing some material.
Multiple forms of N‐acetyl‐β‐hexosaminidase in developing tadpole fins
Authors: Stuart Elizabeth S. , Everett Gale Beliveau , Fischer Mark S. 
Published: June 2005

AbstractThe degradative enzyme N‐acetyl‐β‐D‐hexosaminidase (Hex) (E.C. 3.2.1.30) has been isolated from livers and tail fins of the amphibian R. catesbeiana. Two amphibian hexosaminidases have been resolved by polyacrylamide gel electrophoresis and quantitated by assay of the separated forms. The electrophoretic mobilities of the hexosaminidases were the same whether isolated from liver or tail tissue. The ratio of hexosaminidase enzymes is constant and independent of developmental stage, tissue source, or method of preparation. It has been concluded that tail resorption and increases in Hex activity are not initiated by changes in the ratio of enzymes and that the net affect of any changes in protein synthesis and degradation must leave the ratio of forms unaltered.
The effect of perfusate oxygen levels on CO2 excretion in the perfused gill
Authors: Haswell M. S. , Perry S. F. , Randall D. J. 
Published: June 2005

AbstractCO2 excretion across the perfused trout gill was found to fall to levels approaching zero after 20–30 minutes perfusion with perfusates with oxygen tensions at atmospheric levels. When perfusate oxygen levels were lowered by bubbling with nitrogen, CO2 excretion rates remained stable at least 4–6 hours. The ability to maintain a viable perfused gill preparation with respect to CO2 excretion may also be directly applicable to related studies, e.g. gill ion regulation.
Chimaera studies of the origin and formation of the pectoral musculature of the avian embryo
Authors: Beresford Bonnie , Le Lievre Christiane , Rathbone Michel P. 
Published: June 2005

AbstractCervical, brachial, and thoracic somites and brachial somatopleure were transplanted from quail into 2‐day chick embryos to determine their contribution to the formation of the pectoralis major muscle. The results show that the musculature of the pectoralis major and pectoralis minor is derived entirely from brachial somites (16–20) while the brachial somatopleure provides much of the connective tissue of these muscles. Migration of somitic cells into the somatopleure appears to begin before the somites are fully formed. The primordium of the pectoralis muscle forms at the base of the wing bud and extends ventro‐caudally into the thoracic area to attach to the sternum.
Removal of amino acid during a single passage of water across the gill of marine mussels
Authors: Wright Stephen H. , Stephens Grover C. 
Published: June 2005

AbstractThe clearance of amino acid during a single passage of inhalent water across the gills of marine mussels was studied. Samples of excurrent water were collected and analyzed for their content of 14C‐labeled amino acids and total primary amines. Comparison with concentrations measured in the ambient medium revealed that mussels are capable of removing large fractions of the amino acid present in inhalent water in a single passage across the gill surfaces. At low rates of pumping, Modiolus demissus was capable of removing 95% of the 14C‐glycine from a 1μ M solution. Efficiency of clearance of amino acid was inversely related to pumping rate; absolute rate of uptake was directly related to pumping rate. Concentration related changes in uptake rate and efficiency of clearance indicated that the effective Kt of glycine uptake by intact Mytilus californianus and Modiolus demissus is between 2 and 5μ M. These values are an order of magnitude lower than published figures for Kt of glycine uptake by preparations of isolated gill tissue from these animals. This discrepancy is probably the result of an increase in the effective thickness of unstirred layers on the surfaces of isolated gills. Net clearance of glycine by M. californianus was observed to occur from concentrations as low as 0.28μ M and, from concentrations of 1μ M and less, an average of 20% of the total primary amine offered initially as glycine was removed during a circuit of inhalent water through the animal. Hence, transepidermal transport processes for amino acids in marine mussels are adapted to function efficiently at substrate concentrations found in their normal environment, and can provide a significant supplemental input of reduced carbon and amino nitrogen for these animals.
Persistence of the nychthemeral rhythm of melatonin secretion in pinealectomized or optic tract‐sectioned trout (Salmo gairdneri)
Authors: Gern William A. , Owens David W. , Ralph Charles L. 
Published: June 2005

AbstractIn a preliminary investigation, what appeared to be melatonin was measured in the plasma of pinealectomized trout using a specific and sensitive radioimmunoassay. Later, following the combined procedures of thin‐layer chromatography and radioimmunoassay, the immunogenic molecule measured in pinealectomized trout plasma was verified as melatonin. After this validation procedure, plasma melatonin titers were assessed using RIA in pinealectomized, sham pinealectomized or intact rainbow trout either at mid‐photophase or mid‐scotophase. Results demonstrated that pinealectomy significantly reduced plasma melatonin measured at mid‐scotophase, compared to the midscotophase values for either the sham‐operated or intact animals. Interestingly, pinealectomized animals continued to show significantly elevated, mid‐scotophase plasma melatonin titers when compared to the mid‐photophase values. The same was true for the sham‐operated and intact groups.In a second experiment, it was found that severing the optic tract (optictract‐section) did not alter the rhythm of melatonin measured in the plasma. This indicates that the trout pineal may monitor the environmental photoperiod directly, thereby controlling the rhythmic fluctuations in plasma melatonin. Optic tract‐section did cause a significant increase in the mid‐scotophase melatonin titer. This increase may be due to stress caused by sensory deprivation.
Breakdown of the germinal vesicle in bovine oocytes cultivated in vitro
Authors: Motlík J. , Koefoed‐Johnsen H. H. , Fulka J. 
Published: June 2005

AbstractBreakdown of the germinal vesicle (GV) was studied in bovine follicular oocytes cultivated in vitro. The intact GV of control oocytes did not correspond to the findings in porcine oocytes (GV I). Instead it was characterized by a nuclear membrane and a few chromocenters in finely granular nucleoplasm (GV II). After two and three hours of cultivation, GV III predominated (50% and 64% respectively). Faintly‐staining chromatin and after a longer interval in the form of filaments also appeared round the chromocenters. After four hours, 35.8% of the oocytes were still at stage GV III but the GV of 46.6% of the oocytes already contained filamentous bivalents (GV IV). After five hours, GV IV (59.7%) was typical, with a less distinct nuclear membrane and condensing bivalents. GV breakdown was completed in 30.4% of the oocytes after five hours of cultivation and in 92.5% after six hours.
The mode of action of potassium ions on the leukophores of a freshwater teleost, Oryzias latipes
Authors: Iga Tetsuro 
Published: June 2005

AbstractPigment migration within leukophores of Oryzias latipes (a freshwater teleost) is under nervous regulation. Isotonic KC1 induced pigment dispersion in vitro in innervated leukophores, whereas in most of the denervated leukophores the ionic stimulation did not cause the pigment dispersion within the cells. These results show that K ions act through nervous elements on the leukophores to disperse their pigment granules. Local application of the KC1 solution on a scale indicated that the ions act on the nerve terminals situated close to the leukophores to induce the release of a neurotransmitter causing pigment dispersion in leukophores. A few of the leukophores showed a slight pigment dispersion to the ionic stimulation after denervation. It is inferred from this that K ions act also directly on the pigment cells themselves. The pigment‐dispersing response of innervated leukophores induced by the K stimulation was not all‐or‐none type, but increased in a graded manner with the increase in the K concentration in the medium. The threshold concentration of K ions was about 17.3 mM. Full dispersion of the pigment was brought about with a K concentration above 33.3 mM.
Apparent trophoblast giant cell production in vitro by core cells isolated from cultured mouse inner cell masses
Authors: Wiley Lynn M. 
Published: June 2005

AbstractMouse ICM's that were isolated from blastocysts by immunosurgery and subsequently cultured for four to five days were tested for their ability to form trophoblast giant cells (TGC's) in vitro. The cores were isolated from such ICM's by a second immunosurgery and cultured for 7 to 14 days. After two days of culture a variable percentage (30%–90%) of the ICM cores produced outgrowths containing cells that resembled those of cultured ectoplacental cone. Then the outgrowths became amitotic and produced vacuolated cells that enlarged to dimensions of 200 × 375 μm with nuclei as large as 53 μm in diameter. The time course of their development from the ICM cores, their morphology and their nuclear diameters suggest that these large cells were TGC's.
Neuronal death in the development of normal and hyperplastic spinal ganglia
Authors: Bibb Harold D. 
Published: June 2005

AbstractThe increase of the peripheral area available for innervation by the ninth spinal ganglion of larval Rana berlandieri was accomplished by unilaterally removing at stage V two (numbers 8 and 10) of the three (numbers 8, 9, and 10) ganglia that normally provide the bulk of the sensory innervation to the hindlimb. Peripheral increase significantly enhanced nerve cell number, and the change in neuronal number with developmental stage was also significant. The increase in nerve cell numbers in affected ganglia of 86% over control values at stage XVI compares favorably with the results of workers using different techniques.The effect of peripheral increase on normally occurring neuronal degeneration during the development of the hyperplastic condition through early and middle larval stages was determined. While the data show a trend toward the presence of fewer degenerating neurons in peripherally overloaded than in control ganglia through stage X, the differences in the numbers of dying nerve cells were not significant. This fact and other considerations suggest that a mechanism other than or in addition to a reduction in the level of neuronal degeneration must be operative to account for the increase in the number of neurons present in ninth ganglia with expanded peripheries.Results are discussed in the context of the temporal pattern of the proliferation of cells that differentiate as neurons, the establishment of central‐peripheral connections, and neuronal degeneration.
The role of asters in the localization of the factors that specify the apical tuft and the gut of the nemertine Cerebratulus lacteus
Authors: Freeman Gary 
Published: June 2005

AbstractThe factors that specify the apical tuft of the pilidium larva are located primarily in the vegetal half of the unfertilized egg. Between fertilization and the 8‐cell stage these factors become localized in the animal hemisphere of the embryo. The factors that specify the gut of the pilidium larva are distributed throughout the unfertilized egg. Between fertilization and the four‐cell stage these factors become localized in the vegetal half of the embryo.The removal of the meiotic apparatus that mediates polar body formation and the treatment of eggs with inhibitors that prevent aster formation, inhibit the localization of the factors which specify the apical tuft and the gut. The induction of asters in unfertilized eggs causes a precocious localization of these factors.