bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiological adjustments to dilution of the external medium in the lip‐shark Hemiscyllium plagiosum (bennett). II. Branchial, renal and rectal gland function
Authors: Wong T. M. , Chan D. K. O. 
Published: June 2005

AbstractIn undiluted sea water, the lip‐shark Hemiscyllium plagiosum excretes urine high in Mg++ and rectal‐gland fluid with high concentrations of Na+ and Cl−. Urea is excreted largely by the gills (87%), but also by kidney (5%) and rectal gland (6%).In 50% sea water, the urine flow rate increases while the rate of excretion of Mg++ decreases. The rectal gland continues to secrete a fluid with Na+ and Cl− hypertonic to those of plasma. Branchial loss of urea is diminished as a result of a decline in plasma‐urea concentration so that the clearance rate is unaffected. The U/P ratio for urea increases and the kidney excretes 48.4% of the total urea loss. However, this change in excretion of urea is too small to account for the concomitant decline in body urea content indicating that a reduction in the rate of biosynthesis of urea occurs.
The effects of hydrocortisone and bacterial lipopolysaccharide on the anti‐erythrocyte response in the spleens of adult Triturus viridescens
Authors: Ruben Laurens N. , Gwinnell Esther M. 
Published: June 2005

AbstractThe effects of hydrocortisone (HC) and bacterial lipopolysaccharide (LPS) have been tested separately and in combination, on the antigen‐binding response of splenocytes of the newt, Triturus viridescens immunized with horse erythrocytes (HRBC). The timing of the presentation of each was made relative to when challenge with either low (0.0025%) or high (25%) doses of the immunogen (HRBC) was effected. Our results showed inhibition of both low and high dose responses by HC and additionally suggested that the helpercell population of the newt is HC‐sensitive. LPS given four days prior to antigen challenge initiated the generation of antigen‐binding cells which enhanced the low, but not the high dose response. The use of LPS in conjunction with HC provided suggestive evidence that those LPS stimulated cells which had enhanced the low immunogen dose antigen‐binding cell response were HC‐resistant. Thus LPS may stimulate a non‐helper cell population in the newt which is HC‐resistant. The use of these two immunologic probes has provided supportive evidence on the heterogeneity of the lymphoid population of the newt, Triturus viridescens.
Analysis of a newly‐isolated temperature sensitive maternal effect mutation of Drosophila melanogaster
Authors: Fausto‐Sterling Anne , Weiner Amy J. , Digan Mary Ellen 
Published: June 2005

AbstractA mutation located near the tip of the X chromosome in Drosophila melanogaster has been isolated, and its developmental effects described. This mutation (1(1)ts‐1) is temperature sensitive, and at permissive temperature (18°C) develops normally. However, zygotes from females raised or aged at restrictive temperature (28°C) never hatch, regardless of the embryonic genotype. Midgut formation is abnormal in lethal zygotes and dorsal closure is probably incomplete. Temperature shift experiments have shown that the zygotic lethality is governed by a temperature sensitive period in oocytes of stage seven or older. If viable 1(1)ts‐1 embryos are shifted to restrictive temperatures, they develop as far as the pupal stage, but never eclose. The temperature sensitive period for pupal lethality includes the last 2.5 days of pupal development and does not involve a maternal effect.
Cytodifferentiation in the accessory glands of Tenebrio molitor. II. Patterns of leucine incorporation in the tubular glands of post‐ecdysial adult males
Authors: Happ George M. , Yuncker Christine , Huffmire Susan A. 
Published: June 2005

AbstractThe tubular accessory gland of male mealworm beetles undergoes rapid and progressive terminal differentiation in the 8‐day period after ecdysis to the adult. Total protein and RNA content are maximal at five and eight days respectively. Rates of leucine incorporation rise gradually through the first four days and then increase abruptly in the 5‐ to 7‐day interval. SDS‐polyacrylamide gel electrophoresis demonstrates a variety of proteins; two classes with high mobility (Class A and B) appear prominent in homogenates of 5‐ to 8‐day glands.Double‐label procedures show that as the glands mature, an increasing proportion of the total leucine incorporation passes into Class A and B proteins, until at eight days, Class A and B proteins account for 50% of the total for the gland. The relative incroporation into A vs. B also changes linearly over this interval. The developmental program of the tubular gland includes both a linearly biosynthetic increase in the proportion of differentiation‐specific proteins and an abrupt change in the overall rates of leucine incorporation.
The role of cortical pattern in timing of cell division and morphogenesis in Stentor
Authors: de Terra Noël 
Published: June 2005

AbstractThis paper describes experiments involving reciprocal exchange of the oral apparatus between a large (L) and a small (S) strain of Stentor coeruleus. Mature L‐strain stentors given an S‐strain oral apparatus formed an oral primordium in response to the presence of abnormally small oral structures and mostly divided although a few reorganized instead. Conversely, when S‐strain stentors in early division were given a large L‐strain oral apparatus, they resorbed the developing primordium and returned to interphase. When combined with previous results, these findings provide evidence for the hypothesis that the time of cell division in Stentor is determined by a “critical” ratio between the size of the oral apparatus and the size of the cell body (somatic) cortex. This ratio develops because the somatic cortex grows during interphase and the oral apparatus does not. Cell division in Stentor therefore appears to be initiated by a cortical pattern change resulting from cell surface growth during interphase.
Epidermal‐dermal tissue interactions between mutant and normal embryonic back skin: Site of mutant gene activity determining abnormal feathering is in the epidermis
Authors: Brotman Harris F. 
Published: June 2005

AbstractThe site of the scaleless gene's activity in the development of abnormal feathers was determined by reciprocally recombining epidermis and dermis between normal and scaleless chick embryos and culturing the recombinants for seven days on the chorioallantoic membrane.When recombined with a common dermal source, feather development is enhanced by scaleless high line as compared to scaleless low line epidermis. Against a common responding tissue, 7‐day normal back epidermis, significant differences were not found in feature inducing ability between normal, scaleless high line and scaleless low line dermis. It was concluded that, in relation to abnormal feathering, these tissue interaction reveal that the site of the scaleless gene's activity is the epidermis.A model of tissue interactions in the development of normal and abnormal feathers is presented. According to the model, the focus of the scaleless mutation and the genes accumulated by selection for high or low feather numbers is the epidermis, the effect being that the reactivity of the epidermis to dermal stimuli is altered, Subsequently, the epidermis controls the morphogenetic organization of the dermis. The scaleless dermis is presumed to contain normal positional information for the determination of feather structure and pattern.
The production of ganglionic hypertrophy in Rana pipiens larvae
Authors: Bibb Harold D. 
Published: June 2005

AbstractThe periphery available to the ninth spinal ganglion of Rana pipiens larvae was effectively increased by the unilateral removal at stage V of two (8 and 10) of the three (8, 9 and 10) spinal ganglia which normally provide the bulk of the sensory innervation to the hindlimb. The levels of the resulting hypertrophy of the ninth ganglion were found to compare favorably with those produced by other workers using other techniques.The effect of peripheral increase on mitotic activity, nerve cell number, and neuronal size (as indicated by nuclear cross sectional area) was determined. Differences in nuclear cross sectional area between neurons in hypertrophic and control ganglia were not found to be significant; however, the interaction between peripheral increase and developmental stage was found to be significant, leaving open the possibility that neurons might temporarily respond to peripheral increase by increasing in size.Mitotic activity and neuronal numbers in ganglia with increased peripheries were greater than those in controls at all stages at which counts were made. It is concluded that either, or both, of two mechanisms could be active in producing the observed neuronal hyperplasia in hypertrophic ganglia. Daughter products from the increased numbers of mitoses could provide additional cells which differentiate to become neurons, or normally occurring neuronal loss could be reduced.Results are discussed in the context of current ideas dealing with the regulation of neuronal numbers.
Pituitary enhancement of wolffian lens regeneration in vitro: Spatial and temporal requirements
Authors: Connelly Thomas G. 
Published: June 2005

AbstractWhen irido‐corneal complexes (ICC's) from eyes of adult newts (Notophthalmus viridescens) are cultured on top of pituitary glands they produce advanced lens regenerates in up to 90% of the cases (this report and Connelly et al., '73). To determine if the iris and pituitary gland must be in direct contact with each other in order to produce this enhancement of lens regeneration, ICC's were cultured next to pituitary glands or separated from them by a Nuclepore filter. Cultures behaved as ICC's cultured in the absence of the pituitary gland and produced few advanced lens regenerates. To determine how long the iris and pituitary must be in contact for the enhancement to occur, ICC's were explanted and 5, 10 or 15 days later pituitary glands were placed beneath the dorsal iris pupillary margin. There was a progressive decrease in the number of advanced lens regenerates formed in cultures receiving pituitary glands later than five days after initial explantation of the iris. The conclusions drawn from these experiments are that the iris and pituitary gland must be in extensive direct contact during the first five to ten days in culture in order for pronounced enhancement of lens regeneration to occur.
Polymorphism and reproductive mode in the rotifer, Asplanchna sieboldi: Relationship between meiotic oogenesis and shape of body‐wall outgrowths
Authors: Kabay Michel E. , Gilbert John J. 
Published: June 2005

AbstractSexuality and polymorphism are closely coupled in the rotifer Asplanchna sieboldi. In a graded response to dietary tocopherol, embryos develop body‐wall outgrowths of various sizes and shapes. Also in a graded response to this compound, some of the affected females produce eggs undergoing meiotic instead of mitotic oogenesis. The haploid eggs of such mictic females develop parthenogenetically into males instead of females. The incidence of mictic females among animals with different shapes was studied among cohorts from mothers subjected to different inducing conditions. The hypothesis that external tocopherol concentrations absolutely fix the probability of meiotic oogenesis was rejected. The other extreme hypothesis, that the probability of meiotic oogenesis is fixed by morphotype, was rejected for animals at the low end of the morphotypic scale but accepted for the more strongly‐affected individuals. The probability of meiotic oogenesis is thus constant for the higher morphotypes. The ascertainment of morphotype frequencies in natural or laboratory populations may suffice for estimating the incidence of sexual forms; furthermore, studies of factors affecting the body‐wall‐outgrowth response may also bear directly upon regulation of sexual reproduction in this species.
Studies of the development of frog hemopoietic tissue in vitro. I. Spleen culture assay of an erythropoietic factor in anemic frog blood
Authors: Carver Franklin J. , Meints Russel H. 
Published: June 2005

AbstractA new in vitro technique has been described for demonstrating the presence of an erythropoietic factor in the circulating blood of frogs. The assay system consisted of MC33 medium, erythropoietically active spleen cells from Rana pipiens, and plasma or serum from frogs made anemic via phenylhydrazine or bleeding. The spleen cells, which remain erythropoietically active for up to nine days, were found to incorporate 59Fe, [3H] thymidine, [3H]uridine, and [3H]leucine at a greater rate in the presence of plasma or serum from anemic versus normal frogs. The hormones triiodothyronine, prolactin, and erythropoietin were not effective in eliciting an hemopoietic response. The data presented suggest that the spleen from that adult frog is a major site of erythroid differentiation and maturation.
Ontogenetic change in molecular and functional properties of blood of garter snakes, Thamnophis sirtalis
Authors: Pough F. Harvey 
Published: June 2005

AbstractAt birth the blood of garter snakes (Thamnophis sirtalis) has high oxygen affinity (P50 at 25°C and pH 7.2 = 21 mm Hg), low hematocrit (14%), and a high proportion of inactive hemoglobin (44%). Growth of the snakes is accompanied by a steady decrease in oxygen affinity (P50 = 44 mm Hg in adults), increased hematocrit (to 44%), and decreased inactive hemoglobin (to 3%). These adult values are reached in the second or third year of a snake's life. There is a continuous change in the electrophoretically separable hemoglobin fractions during this period, but there is no ontogenetic change in the oxygen affinity of phosphate‐stripped hemoglobin in solution. Organic triphosphates do not fully explain the ontogenetic change in blood oxygen affinity.Similar ontogenetic changes in blood oxygen affinity were found in two other species of snakes. The unusual morphology of snake lungs and consequent changes in pulmonary pO2 and pCO2 during ontogeny may be the basis for the unusual relationship between body size and blood oxygen affinity in snakes.
Alteration of structure and penetrability of the vitelline envelope after passage of eggs from coelom to oviduct in Xenopus laevis
Authors: Grey Robert D. , Working Peter K. , Hedrick Jerry L. 
Published: June 2005

AbstractThe vitelline envelope (VE) that surrounds an egg released from the ovary into the coelom of Xenopus laevis differs markedly, in structure and penetrability, from the VE surrounding an oviposited egg. In a coelomic egg, the filaments that form the VE are arranged in distinct fascicles or bundles. The exterior surface of the VE is irregular in contour and is permeated by channels. In an oviposited egg, the filaments are evenly dispersed and lack a fasciculated arrangement; the exterior surface is smooth and no channels are present. The fascicular arrangement of fibrils in the coelomic VE is maintained only at neutral pH, and is not visibly altered by the cortical reaction. VEs from coelomic eggs retain their fasciculated morphology after isolation from the egg. In an in vitro test system, sperm penetrated VEs isolated from oviposited eggs, but failed to penetrate VEs isolated from coelomic eggs. The structural transformation of the VE from the coelomic type to the oviposited type occurs in the first 1‐cm segment of the oviduct, prior to addition of jelly to the egg. Neither intact jelly, solubilized jelly, nor jelly extracts were capable of altering the structural organization of coelomic VEs, suggesting that the structural transformation of the VE is effected by some oviducal factor other than jelly.
Distribution of immunoglobulin determinants on the surface of Xenopus laevis splenic lymphocytes
Authors: Azimi Irandokht Hadji 
Published: June 2005

AbstractThe distribution of surface immunoglobulin (Ig) determinants on Xenopus laevis splenic lymphocytes after combination with divalent rabbit anti‐Ig coupled to ferritin was studied. The electron micrographs showed the presence of immune complexes in 67% of lymphocytes treated at 0°C–4°C. The complexes were located all around the membrane and uniformly distributed in a random fashion. The variation of ferritin grain counts on cell sections is such, that the existence of two major subclasses of Ig‐positive cells may be suggested.Raising the temperature produced a rapid interiorization of the complexes in vesicles without any previous aggregation to form a “cap” having occurred.
Failure of immunoperoxidase staining to detect acrosin in the equatorial segment of spermatozoa
Authors: Garner Duane L. , Reamer Sharon A. , Johnson Lawrence A. , Lessley Bruce A. 
Published: June 2005

AbstractAn immunoperoxidase staining procedure that readily demonstrated acrosin in the rostral portion of the acrosome failed to detect acrosin in the equatorial segment of spermatozoa representing the mammalian orders artiodactyla (bull and boar), lagomorpha (rabbit) and primate (human).
Environmental effects on antifreeze levels in larvae of the darkling beetle, Meracantha contracta
Authors: Duman John G. 
Published: June 2005

AbstractAcclimation of Meracantha contracta larvae collected in late summer to low temperatures, short photoperiods or low relative humidities induces production of a macromolecular antifreeze which functions to depress the freezing and supercooling points of the larvae. Overwintering larvae must be exposed to a combination of high temperature and long photoperiod before the antifreeze is lost.
Electron‐microscope investigations on the endonuclear DNA‐RNA bodies of the midgut epithelial cells of Bacillus rossius (insecta, cheleutoptera)
Authors: Bedini C. , Lanfranchi A. , Montanelli E. , Scali V. 
Published: June 2005

AbstractFourth instar larvae and adults of the stick insect B. rossius develop endonuclear bodies in about 10% of the columnar epithelial cells of the midgut. E.M. sections show that the bodies start as loose bundles of fibrils, independent from the intranucleolar chromatin. Large bodies retain a similar structure but also contain larger fibers and electron dense granules, sometimes clustered in small groups. In the nuclei containing these bodies, the other components are similar to those found in ordinary nuclei, apart from the frequent reduction in size and structural changes of the nucleoli. In the cytoplasm of both ordinary cells and those containing bodies, the rough endoplasmic reticulum is strikingly developed and towards the gut lumen many secretion vesicles are found. In EDTA treated sections the endonuclear bodies show intermingled bleached and unbleached areas, the electron density of unbleached structures being increased when compared with controls and reaching the same contrast as the fibrillar‐granular components of the nucleolus. In DNase treated specimens both the chromatin and the endonuclear bodies lose their contrast; RNase solutions digest the electron dense granules of the endonuclear bodies and the combined action of RNase and DNase further disintegrates the bodies. Ultrastructural and enzyme digestion data therefore indicate a DNA‐RNA composition for the endonuclear bodies and support, together with 3H‐thymidine uptake, the hypothesis that they are the expression of a somatic gene amplification. Their origin distinct from the nucleolar chromatin further suggests that the DNA of the bodies is not rDNA and a possible link of the bodies with the production of digestive enzymes is indicated.
Development of the compound eyes of dragonflies (odonata). I. Larval compound eyes
Authors: Sherk Truman E. 
Published: June 2005

AbstractInterommatidial angles and numbers of ommatidia that viewed each segment of the visual field were mapped for a variety of dragonfly larvae from four families, selected for different behaviors and phylogenetic divergence, by measuring the directions of view of ommatidia contributing to the pseudopupil.The size of the visual field and the amount of interommatidial angle specialization are greater than reported from histological sections, primarily because the optical axes are not perpendicular to the cornea.Each species has interommatidial angle specializations that match its behavior. Larvae which are visual predators (family Aeshnidae) have interommatidial angles which vary from 4.9° in some parts of the eye to as little as 0.13° in the developing ommatidia at the anterior border. A foveal area can be defined with interommatidial angles of 0.2° which is the theoretical limit for ommatidia of their diameter, and is narrower than the interommatidial angles reported for adult insects. Foveal interommatidial angles measured along a vertical plane are considerably smaller than along a horizontal plane, resulting in an extremely elongate pseudopupil.Larvae which are less dependent on vision for prey capture have correspondingly less structural specialization in the eye, but the same pattern of regional variation is still recognizable.In contrast to the great range of interommatidial angles, ommatidial diameters are relatively uniform; the inverse relationship expected for highest visual acuity is not found.
Mitosis in beating cardiac myoblasts treated with cytochalasin‐B
Authors: Sanger Joseph W. 
Published: June 2005

AbstractTime‐lapse pictures of isolated chick cardiac myoblasts grown in a medium with cytochalasin‐B reveal that normal mitotic chromosomal separation and muscle contraction can take place simultaneously. These observations indicate that the contractile stimulation for the cells' myofibrils does not affect the movement of the chromosomes and that the cell can regulate two different motile systems inside one cell.
An allelic isozyme of mouse PGK‐2 with low activity
Authors: Vandeberg J. L. , Blohm S. V. 
Published: June 2005

AbstractTwo allelic isozymes of PGK‐2, the testicular form of phosphoglycerate kinase, have been described previously in mice. Evidence is now presented for a third allelic isozyme, which is negatively charged and which exhibits much less enzyme activity than the other two.
The effects of actinomycin D and cycloheximide upon the ultrastructural localization of 3H‐DOPA in differentiating chick neural crest melanocytes in vitro
Authors: Brumbaugh J. A. , Schall D. G. 
Published: June 2005

AbstractCultured neural crest melanocytes from chick embryos were treated with actinomycin D or cycloheximide. The effects of these inhibitors upon melanogenesis was determined by monitoring the incorporation of 3H‐DOPA into premelanosomes and melanosomes using high resolution autoradiography.Seven‐day cultures were treated with actinomycin D (1 μm/ml) or cycloheximide (1 μm/ml) for five hours with the terminal three hours in labeled medium (0.5 m Ci/ml). They were compared to control cultures which were labeled three hours in the absence of inhibitors. Actinomycin D reduced the quantity of silver grains associated with melanogenic organelles to 39.7%‐62.5% (different determinations) of the control value. Similarly, cycloheximide reduced the grain quantity to 58.9% of the control value.In a second type of experiment, 6.5‐day cultures that had been subcultured once were treated with cycloheximide (1 μgm/ml) for 11 hours with the terminal three hours in 3H‐DOPA. In this case, the quantity of silver grains associated with melanogenic organelles was reduced to 22.7% of the control value.Actinomycin D reduces 3H‐DOPA incorporation by about one‐half in from four to seven hours, while cycloheximide takes from six to seven hours to achieve a similar reduction. Therefore, RNA synthesis is at least as rate limiting as protein synthesis with regard to melanogenesis.Based on determinations from the literature regarding the minimal half‐lives of ribosomal and transfer RNA's in cultured cells it is possible to infer that the main effect of actinomycin D was upon messenger RNA synthesis. Therefore, the ability of differentiating chick neural crest melanocytes to incorporate 3H‐DOPA is under transcriptional control.