bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uptake of ferritin by the mosaic egg surface of Brachydanio
Authors: Donovan Michael , Hart Nathan H. 
Published: June 2005

AbstractThe internalization of membrane from the mosaic egg surface of the zebra fish, Brachydanio, was investigated using anionic ferritin and transmission electron microscopy.The cortical cytoplasm of the 5‐min activated egg showed numerous membrane‐bound vesicles not found in the unactivated egg cortex. Two types of vesicles were identified: uncoated (smooth) and coated. Coated vesicles measured about 0.7 to 0.9 μm in diameter. Coated pits, considered to be precursors to the formation of coated vesicles, were frequently observed at the base of membrane‐lined cortical granule crypts. Anionic ferritin was localized over coated pits and in both smooth and coated vesicles. The absence of any morphological evidence of a surface origin for smooth vesicles suggested these ferritin‐labeled organelles might be formed by coated vesicle fusion.Our results indicate that the plasma membrane redundancy created by the exocytosis of cortical granules in Brachydanio appears to be resolved in part by the internalization of membrane through endocytosis.
The use of chlorotetracycline to localize calcium in neural crest cells
Authors: Moran Denis 
Published: June 2005

AbstractCultured amphibian neural crest cells in the early phases of migration (1–2 days) extend broad, clear cytoplasmic processes known as lobopodia. These regions exhibit rapid changes in the contraction‐relaxation cycle and in substratum adhesion. Because of the putative role of Ca2+ in both cytoskeletal function and cell attachment, its distribution in these cells was studied. Chlorotetracycline (CTC), the Ca2+‐chelating fluorescent probe, was used to investigate whether there is a temporal and spatial localization of Ca2+ in cell regions concerned with movement and attachment. Differentiated neural crest cells (7 days), which contain an abundance of actin stress fibers, were also studied to determine whether these cytoskeletal elements were associated with Ca2+. The results with CTC indicate that in early migratory cells regions of membrane extension and protrusion contain higher levels of Ca2+ and that the actin stress fiber system of differentiating neural crest cells (7 days) is associated with Ca2 +. It was determined that using the CTC in the fixative produced the same labeling profile as when live cells were labeled with the CTC. Use of CTC in the fixative is a decided advantage over treatment of cells with CTC while alive since it avoids the photooxidative damage which normally accompanies fluorescent observations of CTC on living cells.
Immunocytochemical localization of acrosin in boar spermatozoa
Authors: Castellani‐Ceresa Lucia , Berruti Giovanna , Colombo Roberto 
Published: June 2005

AbstractAcrosin was localized on the acrosomal membranes of boar sperm by immunofluorescence and immunoelectron microscopy. Indirect labeling of sperm head sections was performed with an Imposil (iron‐dextran) antibody conjugate. The results of electron microscopy indicated a preferential deposition of the antiacrosin antibodies on the outer acrosomal membrane, although a lesser deposition was also found on the inner acrosomal membrane. No labeling was detected in the acrosomal content when such material was still present.
Studies on mouse germ cells inside and outside the gonad
Authors: McLaren Anne 
Published: June 2005

AbstractSoon after entering the genital ridge, mouse primordial germ cells take either a male or a female pathway of development. Which direction they follow, and how successful their subsequent gametogenesis turns out to be, depends on various factors, including their own genotype and the phenotype of the gonad they inhabit. Experimental situations that have helped to throw light on this problem include XX⟷XY chimeras, XO females, and mice carrying the sex‐reversed gene (Sxr). Further information can be obtained by studying germ cells that fail to enter the genital ridge, as well as culturing isolated germ cells.
A Diffusional route of transport of horseradish peroxidase through the midgut of a fleshfly
Authors: Fishman Lena , Zlotkin Eliahu 
Published: June 2005

AbstractHorseradish peroxidase (HRP) was orally introduced to Sarcophaga falculata flies (0.03–0.3 mg per insect), and its morphological route of transport across the midgut was followed with the aid of light and electron microscopy. During a period of about 30 min HRP was shown to penetrate the peritrophic membrane, to enter the epithelial gut cells through the microvilli, and to spread progressively throughout its cytoplasm and finally across the entire gut wall via the inner plasma membrane, basal membrane, and the outer envelope of muscles. The progressive movement of HRP in the present system was diffusional and continuous, and it did not reveal any cytological characteristics of the well‐known pinocytotic uptake and vesicular transport typical for HRP and other macromolecules in digestive and other biological systems.
Human pancreatic growth hormone‐releasing factor (hpGRF) stimulates growth hormone release in goldfish
Authors: Peter Richard E. , Nahorniak Carol S. , Vale Wylie W. , Rivier Jean E. 
Published: June 2005

AbstractSynthetic human pancreatic growth hormone‐releasing factor (hpGRF) was injected intraperitoneally in different dosages, either as one injection or two injections 3 hours apart, into goldfish. Serum GH levels were increased by certain dosages of hpGRF under both treatments. This is the first demonstration of GH‐releasing activity of hpGRF in a teleost fish.
Trophectoderm cell subpopulations in the periimplantation mouse blastocyst
Authors: Chávez Daniel J. , Enders Allen C. , Schlafke Sandra 
Published: June 2005

AbstractTrophectoderm of the preimplantation mouse blastocyst is composed of two cell subpopulations relative to their proximity to the inner cell mass. The polar trophectoderm overlying the inner cell mass proliferates to form the ectoplacental cone, and the mural trophectoderm endoreplicates and gives rise to giant cells. We examined specific differences in the two trophectoderm cell populations using a lectin (Dolichos biflorus) to detect cell surface characteristics and a simple sugar (D‐Gal) to detect differences in incorporation. During the first day of delayed implantation, the mural trophectoderm presented twice as many lectin binding sites as did the polar trophectoderm. The mural trophectoderm of both nondelaying and delayed implantation blastocysts showed a greater rate of incorporation of the tritiated sugar by presenting more reduced silver grains in radioautograms. These results indicate that the mural trophectoderm and polar trophectoderm are two distinct cell types in the periimplantation blastocyst.
Cell cycle timing in colchicine‐treated sea urchin eggs: Persistent coordination between the nuclear cycles and the rhythm of cortical stiffness
Authors: Yoneda Mitsuki , Schroeder Thomas E. 
Published: June 2005

AbstractCyclic changes in cortical stiffness, condensation‐decondensation of chromosomes, and breakdown‐reformation of the nuclear envelope were found to continue in eggs of Dendraster excentricus treated with colchicine even though mitosis and cleavage were suppressed. Furthermore, a consistent and precise synchronization persisted between these cyclic phenomena; each rise and fall of cortical stiffness coincided with the breakdown and reformation, respectively, of the nuclear envelope. The overall cycle length was prolonged relative to controls because of an extended intermitotic phase, indicating that assembled mitotic microtubules do not influence cell cycle timing in this species. In colchicine‐treated eggs of Strongylocentrotus purpuratus, however, the cortex and the nucleus became arrested in conditions equivalent to metaphase, as if the mitotic phase was indefinitely prolonged. The cortex was stabilized in a state of high stiffness, the chromosomes remained condensed, and the nuclear envelopes remained broken down. In this species, even in the absence of rhythmic change, a strict correlation between the cortical status and the nuclear condition was still consistently observed. The persistence of coordination, in spite of diverse species‐specific responses to colchicine, suggests the existence of a common control mechanism between the cytoplasm and nucleus in normal eggs that is important in cell cycle timing. The insensitivity to colchicine indicates that the mechanism of coordination is independent of microtubules.
Application of recombinant DNA technologies to studies on chicken growth hormone
Authors: Souza Lawrence M. , Boone Thomas C. , Murdock Doug , Langley Keith , Wypych Jette , Fenton Dennis , Johnson Steven , Lai Por H. , Everett Richard , Hsu Rou‐Yin , Bosselman Robert 
Published: June 2005

AbstractMessenger RNA isolated from chicken pituitaries was used to construct a chicken pituitary cDNA library. A chicken growth hormone cDNA clone was isolated using 32P‐labeled mammalian growth hormone cDNA probes. The amino acid sequence (derived from the DNA sequence) of the mature form of chicken growth hormone shows 77% homology with that of bovine growth hormone. The chicken growth hormone cDNA clone was used to generate a vector capable of producing chicken growth hormone in Escherichia coli. The recombinant E. coli‐derived chicken growth hormone was similar to pituitary chicken growth hormone in several biochemical and immunological properties. The recombinant‐derived hormone has been used to establish a sensitive radioimmunoassay for growth hormone determinations made from chicken sera. The chicken growth hormone gene has also been introduced into a retroviral vector capable of establishing productive infections of chicken cells both in in vitro and in vivo. The resulting infections are accompanied by the production of radioimmunoassay‐detecable growth hormone. The concentrations of growth hormone in sera of Leghorn chickens infected with the recombinant retrovirus are three‐ to tenfold higher than in control animals.
Chondrogenesis and skeletal morphogenesis occur despite intervening adipocytes in regenerating newt limbs
Authors: Aulthouse Amy Lynn , Neufeld Daniel A. 
Published: June 2005

AbstractThe interface between bone and blastemal tissues of regenerating newt limbs was examined to determine the nature of “tissue spaces” described earlier. Regenerating limbs were prepared either by aldehyde fixation/osmium postfixation and plastic embedding or by Bouin's fixation and paraffin embedding. The osmium‐stained tissues revealed that the interruptions are predominately adipocytes. They are adjacent to the marrow cavity and apparently originate from it. The adipocytes frequently are present in the midst of aggregating prechondrogenic cells and mature chondrocytes. Paraffin embedded tissues revealed that adipocytes distal to bone may be present at all stages of skeletogenesis. Adipocytes apparently do not hinder prechondrogenic aggregation, chondrogenesis or skeletal pattern formation.
Light flashes of different durations (0.063–3.33 msec) phase shift the circadian flight activity of a bat
Authors: Joshi D. , Chandrashekaran M. K. 
Published: June 2005

AbstractThe phase‐response curve (PRC) for the circadian rhythm in the flight activity of a cave‐dwelling bat, Hipposideros speoris, constructed with 0.063‐msec light flashes, reported here is the first of its kind for any circadian system and is unlike any other phase‐response curves constructed for other nocturnal animals. The phase responding with maximal advances (90°) and the phase responding with maximal delays (0°) of this PRC were exposed to light flashes of systematically varying durations from 0.083 to 3.33‐msec. For 0° phase, the flashes of 0.063‐3.33 msec effected delay phase shifts of comparable magnitude. For 90° phase, the flashes of 0.063‐1.0 msec effected advance phase shifts, whereas 3.33‐msec flashes effected unmistakable delay phase shifts with advancing transients. Phase shifts evoked with such light flashes are further compared with phase shifts evoked with pulses of longer durations (15 min to 2.8 hr) for H. speoris.
Production of pyruvate by isolated mouse cumulus cells
Authors: Leese Henry J. , Barton Alison M. 
Published: June 2005

AbstractCumulus cells were isolated by hyaluronidase treatment of whole cumulus masses from superovulated, non‐mated mice. The cells, in groups of approximately 200, were incubated for up to 4 h in 50 nl medium M2 at 37°C, and serial 3‐nl samples assayed for pyruvate using an ultramicrofluorescence technique. With 5.55 mM glucose, 23.3 mM lactate, or a mixture of the two substrates, the cumulus cells formed pyruvate at rates of 10.2, 9.6, and 8.9 fmol/cell/h, respectively. The concentrations of glucose, pyruvate, and lactate, as measured in 3‐nl aliquots of rabbit oviduct fluid were 1.5 mM, 0.3 mM, and 3.7 mM, respectively. When incubated with 1 mM glucose and 3 mM lactate, mouse cumulus cells formed 7.5 fmol pyruvate/cell/h. The mean number of cumulus cells per ovum within a cumulus mass was 2,060. Intact cumulus masses from mated and non‐mated superovulated mice, incubated with 1 mM glucose and 3 mM lactate, formed 22.6 and 23.3 pmol pyruvate/ovum/h, respectively. The results suggest that pyruvate production by cumulus cells may be important in supporting the nutrition of unfertilized and fertilized ova, and of spermatozoa, within the oviduct lumen.
Somatic and germ cell chimerism in chimeric mice between strains of high litter size and regular litter size
Authors: Watanabe Tomomasa 
Published: June 2005

AbstractCFO is an inbred strain of mice showing a high litter size. The high fertility of CFO is due mainly to a very low embryonic death rate during uterine development. C57BL and 129 strains are characterized by regular litter size. Crosses were made and CFO ↔ C57BL and CFO ↔ 129 chimeras were produced. In CFO ↔ C57BL mice, coat color of the C57BL predominated over that of CFO; internal chimerism except for that of the gonads was observed to be in the same proportion as the two genotypes, but the genotypic component of the gonads was almost entirely CFO. Germ cells undergoing gametogenesis in the CFO ↔ C57BL mice were almost all derived from the CFO genotype, and the chimeric females showed high fertility just as did the CFO females. In the CFO ↔ 129 mice no obvious skewing toward one genotype was observed in the coat color, but the germ cells undergoing oogenesis in the two types of chimeric females were recognizable as nearly all of the 129 genotype but with the females showing the same high fertility as do the CFO females. This fact suggests that the genotypes of germ cells in the ovary or in developing embryos do not influence fertility, but rather that the litter size is controlled mainly by the uterine environment.
Proportioning and regeneration in fissioned and unfissioned individuals of the planarian Dugesia tigrina
Authors: Mead Robert W. 
Published: June 2005

AbstractRegeneration was examined in fissioned and unfissioned planarians (Dugesia tigrina) in terms of regenerative success and body proportioning. Regenerative success was determined in terms of percent of abnormal regenerates and number of abnormalities per abnormal regenerate. Sections from unfissioned animals were less successful at regeneration than were those from fissioned animals, and body regions located immediately behind the pharynx represented those segments which formed fewer abnormal regenerates as a result of fissioning. Body proportioning was measured as a function of size of head and prepharygeal region to overall body length. A direct correlation was seen in the proportional size of these two parameters, which varied significantly among regenerates. Results suggest that body proportioning is not constant from one excised piece to another but is predictable and dependent on several variables including interval between fission and sectioning, region from which the segment was obtained, and/or original length of the segment.
Pyruvate dehydrogenase complex from ribbed mussel gill mitochondria
Authors: Paynter Kennedy T. , Karam George A. , Ellis Lehman L. , Bishop Stephen H. 
Published: June 2005

AbstractThe pyruvate dehydrogenase complex has been demonstrated in high speed pellet preparations from sonicated ribbed mussel gill mitochondria. The activity of the complex is inhibited by low chloride (< 100 mM) concentrations, EDTA (1 mM), succinate, ATP, and NAD/NADH ratios below 4. Inhibition by EDTA is relieved by addition of 10 mM MgCl2‐1 mM CaCl2. ATP inhibition was enhanced by NaF and reversed by high Mg+ + concentrations in the absence of NaF. Pyruvate and thiamine pyrophosphate inhibited the inactivation by ATP. The nonhydrolyzable ATP analog AMP‐PNP caused inhibition of the overall catalytic activity that was identical to ATP. Factors involved in the ATP inhibition and Mg+ + reversal are lost with freezing or cold storage. Preliminary results using γ‐32P‐ATP indicate that a protein kinase that phosphorylates the α subunit of E1 (pyruvate dehydrogenase) from the mammalian PDC is associated with the gill PDC. The activity of the complex may be regulated by a phosphorylation/dephosphorylation mechanism and by the relative levels of substrates, products, and other metabolites in the mitochondria.
Individual variation in maximum aerobic capacity: Cardiovascular and enzymatic correlates in Rana catesbeiana
Authors: Walsberg Glenn E. , Lea Malcolm S. , Hillman Stanley S. 
Published: June 2005

AbstractWe quantified natural variation in maximum aerobic capacity (V̊02max) exhibited by a free‐living by a free‐living population of bullfrogs (Rana catesbeiana) and examined the degree to which such variation is associated with key parameters of the systemic oxygen transport apparatus and oxidative enzyme (citrate synthase) activity at the tissue level. Regression analysis of these data revealed that only ventricle mass and hemoglobin concentration accounted for significant fractions of the variation in V̊02max. Neither variation in maximum heart rate nor in citrate synthase activity were significantly correlated with individual variation in maximum aerobic capacity. These results support the contention that, in at least some taxa, maximum aerobic capacity is limited by the ability of the cardiovascular system to deliver oxygen to the tissues.
Biomineralization in the presence of calcium‐binding phosphoprotein particles
Authors: Marsh M. E. 
Published: June 2005

AbstractThe innermost shell lamella, which coats the inner surface of the shells in the estuarine clam Rangia cuneata, is a dynamic structure with a variable composition. In some populations the lamella is a phosphoprotein‐rich structure devoid of crystalline mineral, and in others it is a glucosamine‐rich structure often containing barite (BaSO4) inclusions. Mineral depositions was artificially stimulated in Rangia containing glucosamine‐rich lamellae by scratching the inner shell surface. After stimulation, the lamellae were transformed into phosphoprotein‐rich structures in which aragonite (CaCO3) was deposited. The mineral grew in spherulitic and dumbbell‐shaped clusters characteristic of aragonite precipitated from strictly inorganic solutions. This study demonstrates that phosphoprotein particles accumulate in the innermost shell lamella during stimulated biomineralization but neither inhibit mineral deposition nor influence the crystal habits. Since phosphoprotein particles are high capacity calcium‐binding proteins, they may be the source and transport vehicle for the calcium ions utilized in shell mineralization.
Lectin binding to newt epidermis: Fluorescent localization and effects on motility
Authors: Mahan James T. , Donaldson Donald J. 
Published: June 2005

AbstractThe ability of seven lectins to bind to newt epidermal cells and influence their motility was examined. Of the seven fluoresceinated lectins applied to frozen sections containing intact newt skin and migrating epidermis (wound epithelium), only Con A (concanavalin A), WGA (wheat germ agglutinin), and PNA (peanut agglutinin) produced detectable epidermal fluorescence. Con A and WGA each heavily labeled all layers of intact epidermis, but PNA bound only to the more superficial layers. In contrast to a single population of labeled cells in migrating epidermal sheets after treatment with Con A, there were both labeled and unlabeled cells after exposure to either WGA or PNA. The wound bed was labeled by both Con A and WGA, but not by PNA. DBA (Dolichos bifloris agglutinin), RCA I (Ricinus communis agglutinin), and UEA (Ulex europaeus agglutinin), did not produce significant fluorescence with either migrating or intact epidermis. In general, inhibitory effects on epidermal motility correlated with the binding studies. Thus, Con A, WGA, and PNA, the lectins which clearly bound to the epidermis, all produced a concentration‐dependent depression in the rate of epidermal wound closure. RCA was somewhat paradoxical in that it was moderately inhibitory despite showing essentially no binding. The effects of SBA and UEA were equivocal. DBA had no effect. These results indicate that the inhibition of motility produced by Con A that we have described previously is not peculiar to this mannose‐binding lectin, but is shared by at least one lectin with an affinity for D‐GlcNAc (WGA), and one with an affinity for B‐D‐Gal(1‐3)‐D‐GalNAc (PNA). The fact that PNA labeled some migrating cells and the superficial layers of intact epidermis suggests that wound epithelium is derived, in part, from cells in the outer layers of the epidermis, or that the cell surface of the deeper cells becomes more like superficial cells during migration.
Microfilaments appear in boar spermatozoa during capacitation in vitro
Authors: Saxena Neerja , Peterson R. N. , Saxena N. K. , Russell L. D. 
Published: June 2005

AbstractBoar spermatozoa were in a capacitation medium and examined for the presence of filamentous actin by using the fluorescent probe NBD‐phallacidin. F‐actin was not observed in uncapacitated sperm, but developed in most regions of the cell during the capacitation period. Fluorescent staining was most intense in the flagellum. When fresh seminal plasma was added to capacitated sperm and the sperm was further incubated, F‐actin was no longer observed. In view of previous experiments which indicated that plasma membrane protein (PMPs), including a major integnal PMP, move out of the sperm head into the flagellum during capcitation and that this movement is inhibited by the microfilament poison cytochalasin D (Peterson, Saxena, Saxena, and Russell: Biol. Reprod., in press, '86), we suggest that actin‐PMP interactions play a major role in capacitating boar spermatozoa.