bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maturation of the mouse oocyte in vitro. I. Sequence and timing of nuclear progression
Authors: Donahue Roger P. 
Published: June 2005

AbstractLiberation of mouse follicular oocytes into a chemically defined Krebs‐Ringer salt solution with pyruvate is followed by resumption of meiosis and completion of the first maturation division. Examination of fixed whole mount preparations by light microscopy reveals that 90–95% of the germinal vesicles breakdown and proceed at least as far as metaphase I where about 5% arrest; the remainder go on to metaphase II.Three stages of chromatin condensation from the dictyate (germinal vesicle) stage are seen, first with filament shortening forming a chromatin lattice‐work followed by condensation about the nuclear and nucleolar periphery and finally the appearance of discrete bivalents. Just prior to appearance of the spindle, the bivalents are circularly arranged and reach their maximum shortness. Spindle formation is followed by prometaphase I, metaphase I, anaphase I, telophase I with first polar body formation, the chromatin mass stage in which the chromatin assumes a half‐moon shape, prometaphase II and finally metaphase II, the stage at which oocytes arrest both in vitro and in vivo.Examination at one‐two hour intervals reveals first meiotic spindle formation beginning after three hours of culture and metaphase I first appearing at 4 and one‐half hours. After nine hours of culture the majority of the oocytes are in metaphase I and anaphase I first appears at this time. There appears to be a six hour asynchrony in this division, some germinal vesicles requiring six hours to breakdown and the metaphase II stage accumulating between 11 and 17 hours of culture.
Polymorphic control of subunit synthesis for the enzyme lactate dehydrogenase in the newt, Triturus viridescens
Authors: Sherr Charles J. 
Published: June 2005

AbstractThe newt, Triturus viridescens, shows a polymorphism for the genes controlling the synthesis of the enzyme lactate dehydrogenase (LDH). Homozygotes have either of two electrophoretically fast migrating bands. In heterozygotes, the isozymes present in both homozygote classes appear along with three additional isozymes of intermediate mobilities. An additional slowly migrating isozyme is found in all animals. The relationship between the three phenotypic distributions of isozymes in the population is consistent with the predicted phenotypic frequencies made in accordance with the Hardy‐Weinberg Law. No difference in the Km for pyruvate reduction or the thermal denaturation characteristics was noted between homogenates containing different isozyme distributions. The electrophoretically fast moving isozymes in all homogenates are inactivated at a higher temperature than the slowly migrating isozyme. The evolutionary significance of polymorphism for alleles controlling isozyme synthesis is discussed.
Deletion‐transplantation experiments on embryos of Fundulus heteroclitus. I. The posterior embryonic shield
Authors: Brummett Anna Ruth 
Published: June 2005

AbstractExperiments are described in which the differentiative capacity of the posterior embryonic shield of the teleost, Fundulus heteroclitus, was investigated by means of deletion‐transplantation techniques.The posterior embryonic shield, removed from early gastrulae to immediate postgastrulae and grafted into the pericardial cavity of slightly older embryos, exhibits considerable growth and differentiates typical trunk and tail structures involving all germ layers.The donor embryos, in general, develop normal heads to pectoral fin regions. They lack all trunk structures except for gut and some gut derivatives. They frequently differentiate a very small “tail” with unpaired somites. The “tail” sometimes flattens and forms fin rays.Collateral experiments involving the deletion and grafting of various parts of the germ ring provide data in agreement with the conclusion that the posterior embryonic shield supplies the bulk of material for the formation of the trunk and tail in teleosts.The experiments are discussed from the standpoint of their elucidation of gastrulation, trunk and tail formation, embryonic regulation of defects, and endoderm formation in teleosts.
Effect of the interstitial‐cell‐stimulating hormone on testicular enzymes during spermatogenesis
Authors: Hitzeman Sister Jean Walter 
Published: June 2005

AbstractThe activities of 17β‐hydroxysteroid dehydrogenase and of some NADPH‐generating enzymes in the fetal mouse testis during the formation of the accessory reproductive glands indicate that Leydig cells synthesize androgens before gonadotropins are secreted. In the neonatal testis the seminiferous tubules grow rapidly and the relative volume of the intertubular tissues decreases. At the same time the absolute activity of 17βSDH also decreases but there is no evident loss of enzyme activity as the primary spermatocytes begin meiotic prophase. High levels of NADPH‐generating malic enzyme activity coincide with the onset of meiosis and the development of the spermatids, although the activity of 17βSDH remains constant. Both glucose‐6‐phosphate and isocitrate dehydrogenases, which can be activated by gonadotropin, show strong activity prior to spermiogenesis.Significantly increased activities of 17βSDH and the ME occur in 10‐day postpartum intact mice four hours after a single injection of 0.25 unit ICSH. Exogenous gonadotropin stimulates G6PDH and IDH activities during divisions of spermatogonia five days after birth. The pituitary‐Leydig cell axis is stabilized after the beginning of meiosis so exogenous ICSH has little effect on testicular enzymes during the remainder of the first wave of spermatogenesis. Dependence of Leydig cell activities on pituitary gonadotropin seems to occur during pachytene or the early stages of spermatid formation. Androgen synthesis in the murine testis may be associated with the NADPH‐generating ME and IDH as well as G6PDH which has been implicated in other steroidogenic tissues.
In vitro and in situ analyses of the inhibitory effect of Creeper tissues
Authors: Elmer William A. 
Published: June 2005

AbstractThe growth of White Leghorn tibiotarsi, measured as an increase in length, total protein and DNA content, is significantly lower when co‐cultured in the presence of 6.5‐7‐day Creeper tibiotarsi. The growth of White Leghorn tibiotarsi is not affected with increasing age of the Creeper donor. Quantitative measurements of in situ growth of Creeper and White Leghorn tibiotarsi were made for a comparison with the in vitro effect. Creeper rudiments do not accumulate protein as fast as White Leghorn rudiments. Creeper rudiments show a lag phase in DNA accumulation up to the eighth day and then accumulate DNA at the same rate as White Leghorn rudiments. The evidence suggests that Creeper is acting primarily on protein metabolism.
Morphogenesis of the eye lens in a mouse strain with hereditary cataracts
Authors: Zwaan Johan , Williams Randolph M. 
Published: June 2005

AbstractMice carrying the gene “Shrivelled, ” also known as “Cataract‐Fraser” or “Cataracta hereditaria subcapsularis, ” invariably develop lens opacities which are visible when the animals open their eyes on the fourteenth postnatal day.Lens development in normal and mutant embryos is the same until day 14 of gestation. At this stage the nuclei of the lens fibers in the controls are large and vesicular with prominent nucleoli. In the mutants the centrally located nuclei are smaller and darker with indistinct nucleoli. The nuclei of normal fibers remain large and open even after birth; those in the mutants continue to undergo pyknosis after passing through the equatorial zone in the regular fashion. The nuclear degeneration is followed, with a delay of about 24–48 hours, by swelling and vacuolization of the fibers concerned. In the adult the lens core forms an amorphous eosinophilic mass or may partly be resorbed. The cortical fibers remain normal. Anterior polar cataracts develop: the epithelial cells proliferate to form multiple layers of atypical cells, surrounded by lens capsule‐like material.The fiber degeneration may be caused by precocious cessation of protein synthesis after the cell nucleus becomes defunct. The late epithelial aberrations may be secondary to the changes in the underlying fibers and are possibly related to the reactivation of cell replication in the central part of lens epithelium seen after traum.
Budding in Hydra viridis
Authors: Shostak Stanley , Bisbee John W. , Ashkin Claire , Tammariello Robert V. 
Published: June 2005

AbstractThe rate of growth of a population of Hydra viridis by budding is shown to be a function of the frequency of bud‐initiations and not of the duration of bud development. Different rates of growth in populations were imposed by feeding the animals three, five, or seven days a week. The slowest growth rate was observed in animals fed Monday, Wednesday, and Friday, while those fed Monday through Wednesday grew at the same rate as hydra fed Monday through Friday. Not only was the duration of the bud development independent of the feeding schedules, but the duration of each of the stages of bud development was also unaltered despite differences in the frequency of feeding. This rigidity is not explained as a consequence of the distal end of the bud prescribing the course and rate of bud development; removal of the distal end, or replacing it with a distal end from a bud or animal at a different developmental and chronological age, had no effect on the development of the original bud's base or the time of its detachment. It seems that bud‐initiation depends on the parental production of a quantum of cells which can completely support the further development of a bud. Differences in the number of buds produced on any parent would thus be a function of the number of quanta produced.
Influence of estrogen and progesterone on the incorporation of 35S methionine by blastocysts in ovariectomized mice
Authors: Weitlauf Harry M. , Greenwald Gilbert S. 
Published: June 2005

AbstractIncorporation of 35S methionine by mouse blastocysts in vivo, as detected by radioautography, provides a presumptive measure of the blastocysts' protein synthesizing activity. Normally, there is a marked increase in 35S methionine incorporation between 95 and 99 hours post coitum.To determine whether or not ovarian hormones influence 35S methionine incorporation by the blastocysts, mice were ovariectomized on day 4 of pregnancy and injected with progesterone and/or estradiol 17‐β and given a single injection of 35S methionine. The results demonstrate that 35S methionine is incorporated in mouse blastocysts in vivo only after combined progesterone and estrogen treatment; 12 to 14 hours are required for the maximum response. Further, blastocysts were transferred (101–103 hours post coitum) from intact donors to ovariectomized, pseudopregnant recipients that were untreated or treated with progesterone or estradiol. The blastocysts incorporated 35S methionine, thus suggesting that hormonally induced changes in the blastocysts are responsible for initiating protein synthesis.These findings provide a tentative explanation for the mechanism involved in initiating normal implantation and for terminating the embryonic diapause in the delayed implantation of lactation.
Effects of radiations on oral regeneration in Stentor coeruleus
Authors: Burchill Brower R. 
Published: June 2005

AbstractIrradiation with ultraviolet light (254 nm) or ionizing radiation can prolong oral regeneration in the ciliate Stentor coeruleus. The primary response is an interruption in the regeneration cycle, starting soon after irradiation and leading to a delay in the completion of development. The relation of dose to delay, of cells irradiated early in regeneration, is approximately linear. Early stages of regeneration are maximally sensitive, with the peak sensitivity to ultraviolet light occurring slightly earlier than that to ionizing radiation. Cells irradiated with combined doses of both radiations are more affected than cells exposed to either single radiation dose alone. Possible interpretations of the results are discussed.
Hormonal and nutritional requirements for limb regeneration and survival of adult newts
Authors: Tassava Roy A. 
Published: June 2005

AbstractNewts which were fed daily for two weeks prior to hypophysectomy survived significantly longer and regenerated limbs better than newts fasted for two weeks prior to hypophysectomy. Since limbs were amputated five days after hypophysectomy, regeneration was initiated in the complete absence of pituitary hormones.Newts which were hypophysectomized 14 days after limb amputation were found to possess blastemas significantly smaller at eight and also at 16 days after the operation than the blastemas of sham‐operated newts. Thus, hypophysectomy, performed after limb regeneration had progressed through the wound healing and dedifferentiation phases, resulted in a significant retardation in the growth of the blastema.To determine which hormones are essential to normal limb regeneration and survival, newts were hypophysectomized and treated with various combinations of hormones, or grafted with pituitaries from newts or from axolotls (Ambystoma mexicanum). A prolactin‐thyroxine combination, growth hormone, and ectopic pituitary grafts from newts or axolotls, significantly prolonged the life of hypophysectomized newts. These newts also regenerated limbs in a normal fashion. Thyroxine alone, prolactin alone, thyroxine + ACTH, ACTH, or saline were not effective in restoring the health of hypophysectomized newts and were not effective in restoring normal limb regeneration ability.
Protein changes during maturation of the free‐living nematode, Panagrellus silusiae
Authors: Chow H. Hu , Pasternak J. 
Published: June 2005

AbstractThe free‐living nematode Panagrellus silusiae can be grown synchronously through the postpartum period of its life cycle. This period is divided into four phases which in sequence are called the L2, L3, L4 and adult stages. Homogenates from each stage were analyzed electrophoretically in order to discover whether protein changes occur during postembryonic development. Protein patterns in acrylamide gels from L2, L3, L4 and adult stages show no differences in the number of bands (16), although there are differences in the intensity of certain bands at various stages.Definite stage specific patterns were observed when enzyme activity was assayed histochemically. L4 larvae show five sites of lactate dehydrogenase activity in polyacrylamide gel; three of these are found in each of the other stages. L3 larval extracts have five sites of malate dehydrogenase activity; L2 larvae and adults share one of these and L4 larvae have two in common. L4 and adult nematodes each have one MDH type not present in any other stage. L4 larvae produce six sites of α‐naphthyl acetate esterase activity; four of these bands are present in each of the other stages. Both acid and alkaline phosphatase occur as single molecular forms in each postpartum stage.It is concluded that during maturation a precise regulatory program operates to control the sequential appearance of specific enzymatic proteins.
New information from experimental crosses on genetic relationships within the Rana pipiens species group
Authors: Mecham John S. 
Published: June 2005

AbstractDiploid crosses among Rana palustris, R. areolata, R. megapoda, R. montezumae, and three different forms of the Rana pipiens complex demonstrated a high level of genetic compatibility for most combinations. The results support inclusion of R. montezumae within the R. pipiens species group, and suggest a particularly close relationship between R. montezumae and R. megapoda. The only crosses to indicate pronounced incompatibility involved R. p. berlandieri. Crosses between Texas R. p. berlandieri and R. areolata, R. megapoda, and R. montezumae produced lethal syndromes of embryonic abnormalities. The other forms of R. pipiens that occur in Texas, R. p. sphenocephala and the southern plains type, proved to be highly compatible with these same species. Although all R. palustris X R. pipiens crosses produced normal larvae, embryonic defects were most pronounced with R. p. berlandieri. Rana p. spenocephala X southern plains and R. p. spenocephala X R. p. berlandieri combinations are at least moderately compatible. Striking defects appeared in southern plains ♀ X R. p. berlandieri ♂ crosses, however, although development proceeded to larva in crosses between allopatric populations, and hybrid males were fertile. Rana p. berlandieri appears to be highly incompatible with northern R. p. pipiens. The evidence from crossing experiments indicates that R. pipiens berlandieri has a highly distinctive genome, and strongly supports the separation of this from from R. pipiens as a distinct species. Developmental incompatibility in crosses within the R. pipiens species group and within the R. pipiens complex may be influenced by differences in temperature adaptation, but other factors are clearly involved.
Cortical morphogenesis in Paramecium aurelia following amputation of the posterior region
Authors: Chen‐Shan Lily 
Published: June 2005

AbstractThe present paper reports the results and consequences of transverse cuts made between vestibule and cytoproct of Paramecium aurelia. The structural developments of the cortex were observed by the silver impregnation method in successive opisthes (posterior products of fission).
Restitution of the posterior region in successive opisthes. Restitution was associated with the process of fission, most of it occurring at the first fission which yielded opisthes having anterior regions 90% of normal length and posterior regions 70% (as compared with the 30% remaining after amputation). Return to normal was nearly complete during the second fission; after the third fission there was no significant difference from normal.
Incomplete kineties, i.e., kineties that fail to extend to regions where normal kineties do. Incomplete kineties were found in successive opisthes of cut cells. Growth of complete kineties at latitudes posterior to the termini of incomplete kineties shifted these termini more and more anterior at successive fissions. Eventually the posterior terminations of the incomplete kineties fell anterior to the fission plane, removing them from the opisthe formed at this and subsequent fissions.
The kinety patterns in the regenerated posterior region, i.e., the spacing and the angular arrangement of the kineties on the two sides of the cytoproct line. In some opisthes the kinety patterns were similar to but not exactly the same as those of normal cells; in others. The kinety pattern on one side or both sides of the cytoproct line was distinctly abnormal.
Regeneration of the cytoproct. The cytoproct line reappeared within two hours after the first fission of three‐quarters of the opisthes; by the end of the second fission, it was present in almost all opisthes. The cytoproct regenerated in cells with abnormal kinety patterns as well as in those with normal kinety patterns.
Respiratory ammonia filtration, mucous composition and ammonia tolerance in bats
Authors: Studier Eugene H. 
Published: June 2005

AbstractMaximum efficiency of removal of inhaled ammonia by respiratory mucous in three species of mammals has been determined by noting the increase above normal in plasma ammonia and urea nitrogen after exposing the blood in vivo and in vitro hightly ammoniated air. Guano bats, Tadarida brasiliensis, filtered 97.1% of the ammonia present in an inhaled mixture of 1130 PPM (parts per million ammonia). These bats further filtered 73.4% of a 4420 PPM in air mixture, 72.6% at 5040 PPM and 53.9% and 7200 PPM. For little brown bats, Myotis lucifugus, filtering efficiencies of 84.5% at 1330 PPM and 77.5% at 3010 PPM were found. Mice, Mus musculus, were found to filter 76.9% at 870 PPM. Efficiency of respiratory ammonia filtration relates directly to tolerance to inhaled ammonia in these mammals.Sodium, potassium, chloride, carbon dioxide, ammonia and urea nitrogen and protein levels in perfused respiratory tract fluid of the same three species after inhalation of ammonia in air mixtures are reported. In each species, ammonia and urea nitrogen levels in perfused respiratory tract fluid increases as inhaled concentrations of ammonia increase. In guano bats and little brown bats, carbon dioxide levels paralleled increases in ammonia apparently in sufficient quantity to provide the increase in buffering capacity necessary to neutralize absorbed ammonia. In mice, however, carbon dioxide levels dropped as inhaled ammonia levels increased. In no case did electrolyte or protein content change in any way to increase buffering capacity of respiratory mucous except in guano bats where protein levels rise consistently with inhaled ammonia concentrations.
Activation of ribosomal RNA synthesis in initiation of Wolffian lens regeneration
Authors: Reese David H. , Puccia Egidio , Yamada Tuneo 
Published: June 2005

AbstractTissue engaged in the transformation of iris into lens, triggered by lens removal in the adult newt (Triturus viridescens), was labeled in vitro with 14C‐uridine, and the sedimentation profiles of RNA synthesized by the tissue were studied in sucrose density gradients. The radioactivity in the 18S and 28S areas, which is insignificant in the normal iris, increases significantly during 2 to 10 days after lens removal, and subsequently retains a high level until the completion of lens regeneration. These data are interpreted as indicating activation of ribosomal RNA (rRNA) synthesis by lens removal, and are discussed in connection with the ultrastructural modification of the nucleoli. Further data from the radioactive profiles are consistent with the notion that the level of control of rRNA production in this system is the transcription of the rRNA precursor rather than the post‐transcriptional processing of the precursor. The activation of rRNA production described in this paper is the earliest event so far detected in this system, preceding activation of DNA replication, cell replication, and dedifferentiation.
The function of the accessory sex glands in Periplaneta americana (L.). II. The role of the juvenile hormone in the synthesis of protein and protocatechuic acid glucoside
Authors: Shaaya Eli , Bodenstein Dietrich 
Published: June 2005

AbstractThe left colleterial gland, as part of the accessory sex glands of the adult female cockroach, produces a structural protein and the phenolic tanning agent, protocatechuic acid glucoside. Both are needed for the formation of the egg capsule (ootheca), which contains the eggs of the species. The synthesis of the two compounds is under the control of the corpus allatum hormone. Transplanted colleterial glands are able to synthesize protein and glucoside in adult females; in adult males, however, the transplanted glands are able to synthesize only protein. They do not synthesize glucoside, even under the influence of additional juvenile hormone supplied to the male hosts by injection. Yet males produce enough juvenile hormone to promote the synthesis of protein and glucoside by colleterial gland cultured in female hosts. This was demonstrated by combining in parabiotic fusion adult males with decapitated adult females. The adult female apparently contains a factor which in the presence of juvenile hormone is a prerequisite for glucoside but not for protein synthesis. This factor is apparently also absent in nymphs of both sexes. The dependence of protein synthesis on the juvenile hormone provides a quantitative bioassay for estimating the juvenile hormone titer in all postembryonic stages of development. At present, glucoside synthesis can only be used as an indicator for the juvenile hormone concentration of adult females of different ages. The juvenile hormone presumably acts directly on the tissues of the collecterial glands.This paper is dedicated to the memory of Professor Alfred Kühn, one of the great biologists of his time, who died in Tübingen, Germany on November 22, 1968.