bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytochalasin D‐induced triploidy in the mouse
Authors: Speirs S. , Kaufman M. H. 
Published: June 2005

AbstractPrevious attempts to obtain digynic triploid mouse development in vivo have either been entirely or only marginally successful, generally with the production of heteroploid rather than triploid conceptuses. We report that when a single intraperitoneal injection of 15 üg of cytochalasin D is given to recently mated female mice during a restricted period following ovulation induced by exogenous gonadotrophins, between 14 and 18% of conceptuses isolated on the 10th day of gestation had a triploid chromosome constitution. Triploidy was only induced in those eggs that were exposed to cytochalasin D when they were passing through a critical phase of the second meiotic division corresponding to the time when the second polar body was about to be extruded. Exposure to this agent either before or after this critical period only results in the development of normal diploid conceptuses. When females were mated to males carrying an easily recognisable paternally derived ‘marker’ chromosome, convincing cytogenetic evidence was obtained that only digynic triploidy was induced. No examples of diandric triploidy were recognised when conceptuses were analysed on the 10th day of gestation. The technique described therefore represents a simple and direct means of inducing digynic triploid mouse conceptuses whose development potential may be compared directly with that of their normal diploid littermates.
Induction of the acrosome reaction in goat spermatozoa in simple physiological salt solution
Authors: Kusunoki Hiroshi , Kato Seishiro , Kanda Sunao 
Published: June 2005

AbstractThe present study was carried out to determine whether K+, Mg2+, PO43−, and HCO3− in a medium are necessary for inducing the acrosome reaction in ejaculated goat spermatozoa. Washed goat spermatozoa were resuspended in K‐1 medium, containing NaCl, KCl, CaCl2, MgCl2, NaH2PO4, and NaHCO3; in K‐2 medium, containing NaCl, CaCl2, NaH2PO4, and NaHCO3; in K‐3 medium, containing NaCl, CaCl2, and NaHCO3; and in K‐4 medium, containing only NaCl and CaCl2, followed by preincubation in a sealed glass tube at 39.5°C for 1, 2, or 3 h. The sperm acrosome reaction was evaluated by the trypan blue‐Giemsa method and hamster test. The results were essentially the same in all cases. Following preincubation for 1 h, however, the percentage of acrosome‐reacted spermatozoa, the proportion of zona‐free hamster eggs penetrated by spermatozoa, and the average number of spermatozoa in the vitellus of these penetrated eggs were low; all values indicated a significant increase with preincubation for 2 and 3 h. The presence of K+, Mg2+, PO43−, and HCO3− in the medium thus does not appear necessary for inducing the acrosome reaction in goat spermatozoa, since they can undergo the reaction during preincubation in a simple physiological salt solution containing only NaCl and CaCl2 when preincubated in sealed glass tubes at 39.5°C.
Proteolytic activity of specialized surface protrusions formed at rosette contact sites of transformed cells
Authors: Chen Wen‐Tien 
Published: June 2005

AbstractSurface protrusions at the leading edge of a moving cell that make contact with the surrounding extracellular matrix (ECM) are its main motor for locomotion and invasion. Chicken embryonic fibroblasts transformed by Rous sarcoma virus (RSV‐CEF) form specialized membrane rosette‐shaped contact sites on planar substrata as shown by interference reflection microscopy (IRM). Such activity is lacking in normal cells. These rosette contacts are more labile than other adhesion sites, such as focal and close contacts. Ultrastructural studies demonstrate that rosettes are sites at which membrane protrusions from the ventral cell surface contact the substratum. These protrusions are filled with meshworks of microfilaments and contain the pp60src oncogene product, actin, vinculin, and α‐actinin. However, unlike focal contacts, at the rosettes these proteins interact to extend a highly motile membrane. Rosettes have the biological activity of degrading ECM components, as demonstrated by (1) local degradation of fibronectin substrata at sites of rosette contacts, but not focal and close contacts; (2) localization of putative antiprotease antibody at sites of rosette contacts, but not at focal an close contacts; and (3) local disruption of fibronectin matrix at sites of protrusive activity seen by transmission electron microscopy (TEM). In addition, formation of the rosette contact is insensitive to the ionophore monensin, and to inhibitors of proteolytic enzymes, while local fibronectin degradation at rosette contacts is inhibited by inhibitors of metalloproteases, 1,10‐phenanthroline and NP‐20. I consider these membrane protrusions of the rosette contacts in RSV‐transformed cells specialized structural entities—invadopodia—that are involved in the local degradation of the ECM.
Oxygen affinity of monotreme blood: Hypoxic adaptations
Authors: Lutz P. L. , Dawson T. J. , Bonnet E. , Fanning D. 
Published: June 2005

AbstractWhole‐blood oxygen affinity was measured for the duck‐billed platypus and the echidna. For the platypus, p50 was 26.8 Torr O2 at pH 7.4, PCO2 = 36 Torr, and 32.0°C. The H+ Bohr coefficient was −0.286 and was oxygen saturation‐independent. However, at elevated PCO2 (69 Torr) the H+ Bohr effect declined markedly at saturation values below 60%. No specific effect of CO2 on the p50 echidna whole blood was found. In the echidna, p50 was 24.0 Torr O2 at pH 7.4, PCO2 = 36 Torr, and 32.0°C. The H+ Bohr effect was −0.280 and was also saturation‐independent. By contrast, a substantial specific CO2 effect on blood O2 affinity was found (Δlog p50/Δlog PCO2 = 0.114). These data are related to the habitat and mode of life of the respective species.
Autonomous death of amphibian (Xenopus laevis) cranial myotomes
Authors: Chung Hae‐Moon , Neff Anton W. , Malacinski George M. 
Published: June 2005

AbstractThe death of cranial myotomes during Xenopus laevis embryogenesis is employed as a model system to study programmed cell death. The first primary myotomes to differentiate and functionally develop are in the occipital region of the embryonic head. Between stages 27 (tailbud) and 48 (feeding tadpole), they degenerate and disappear in a craniocaudal sequence. Descriptive and experimental studies were undertaken to establish whether this apparent cell (myotome) death program is autonomous or whether it depends on interactions with surrounding tissues (e.g., otic vesicle). Removal of the adjacent otic vesicle did not affect cranial myotome death. Likewise, grafting the otic vesicle to a novel location along the somite file did not induce local myotome degeneration (death). Cranial myotome primordia grafted into the trunk region degenerated on schedule. Trunk myotome primordia grafted to the cranial myotome location did not degenerate. It is therefore concluded that the cranial myotome death program has become autonomous by the time the cranial myotomes reach the developmental stage of segmentation.
Differentiation of the golden hamster oviduct epithelial cells during postnatal development: An electron microscopic study
Authors: Abe Hiroyuki , Oikawa Taneaki 
Published: June 2005

AbstractThe ultrastructural changes in the process of differentiation of the epithelial cells of the golden hamster oviduct during postnatal development were investigated by means of electron microscopy. In the epithelium of the ampulla of the neonatal oviducts, no differentiated ciliated cells or secretory cells were identified. In these undifferentiated cells, free ribosomes were well developed, but rough endoplasmic reticulum (RER) and the Golgi apparatus were undeveloped. Cells undergoing ciliogenesis were first identified at 3.5 days after birth, and some ciliated cells appeared at 4.5 days. In the nonciliated cells, marked changes in the organelles were observed at this time. Subsequently, some nonciliated cells containing well‐developed RER and Golgi apparatus were obsrved at 9.5 to 10.5 days after birth, and a few mature secretory cells were observed at 10.5 days. An increase in secretory granules occurred in the secretory cells at 12.5–15.5 days after birth. Many fully mature ciliated and secretory cells were observed at 15.5 days after birth. After 20.5 days after birth, the epithelium was identical with that of the adult golden hamster. Quantitative data indicated that the differentiation of ciliated cells began earlier and took place over a more extended period of time than did that of the secretory cells in the golden hamster oviduct during postnatal development.
FMRF‐amide immunoreactivity and the midgut of the corn earworm (Heliothis zea)
Authors: Jenkins Alan C. , Brown Mark R. , Crim Joe W. 
Published: June 2005

AbstractThe midgut of the larval corn earworm, Heliothis zea, was examined using light microscopy and immunocytochemistry. Many endocrine‐like midgut cells exhibit immunoreactivity to the molluscan cardioactive peptide FMRF‐amide (FMRFa), and bovine pancreatic polypeptide (BPP). Cross‐reactivity studies demonstrate the immunoreactive material is more FMRFa‐like than BPP‐like. Immunocytochemical surveys and radioimmunoassay of midguts from fed or starved individuals show that the fed animals contain a significantly greater amount of FMRFa immunoreactivity. Radioimmunoassay of hemolymph reveals a significant increase in the amount of FMRFa immunoreactivity in the starved animals. These observations indicate that the changes in the levels of FMRFa immunoreactivity in the midgut and hemolymph may be a midgut endocrine response to changes in the feeding state.
Neuropeptide stimulation of thyrotropin secretion in the larval bullfrog: Evidence for a common neuroregulator of thyroid and interrenal activity in metamorphosis
Authors: Denver Robert J. , Licht Paul 
Published: June 2005

AbstractThe effects of several neuropeptides on in vitro thyrotropin (TSH) secretion by pituitaries of the frog Rana catesbeiana were studied at two stages of development. The relative concentration of TSH secreted into the medium was determined by bioassay using in vitro thyroxine (T4) production by thyroids from adult grass frogs, Rana pipiens. Pituitaries from tadpoles in Taylor‐Kollros stages 17–19 responded to doses of ovine corticotropin‐releasing hormone (CRH) ranging from 10 to 1,000 ng/ml; the same glands did not respond to doses of thyrotropin‐releasing hormone (TRH) between 10 and 1,000 ng/ml. A single dose of 1,000 ng/ml rat growth hormone‐releasing hormone (GHRH) had no effect on TSH release. Pituitaries from postmetamorphic frogs (stage 25) exposed to 1,000 ng/ml ovine CRH secreted concentrations of TSH that were higher on average than controls (four of seven responded), and two of seven responded to 100 ng/ml TRH. These observations raise the possibility for a common central regulator of the thyroid and interrenal axes in metamorphosis in which a CRH‐like molecule might act as an important neuroendocrine stimulus for both corticotropin and thyrotropin secretion. Furthermore, these and previous results with several species of adult anurans (R.J. Denver: Gen. Comp. Endocrinol., 72:383–393) suggest that pituitary TSH responsiveness to TRH develops in frogs after metamorphic climax.
Delayed carpal ossification in N. viridescens efts: Relation to the progress of mesopodial completion in newt forelimb regenerates
Authors: Libbin Richard M. , Mitchell Ormond G. , Guerra Ladislao , Person Philip 
Published: June 2005

AbstractThe persistence of cartilage in the adult newt (Notophthalmus viridescens) forelimb skeletal regenerate has recently been reported by Libbin et al. (J. Exp. Zool., 248:238–242, '88). It is particularly evident in the carpal group, which remains cartilaginous for at least 9 months while all other regrown skeletal parts are either ossified or ossifying. The present investigation was undertaken to determine whether delayed ossification in the adult regenerate recapitulates a pattern evident during the development of the forelimb of the red eft (N. viridenscens' immature terrestrial phase). Right upper limbs of 20 efts were examined at low magnification to establish carpal composition and organization. Among five efts of smallest size (26.54 ± 2.20 mm snout‐to‐vent length), and displaying bright orange dorsal skin coloration, all carpal rudiments were cartilaginous. Eleven efts, intermediate in length (33.88 ± 0.81 mm), and primarily of orange‐tan color, presented a varying pattern of mesopodial ossification characterized by the appearance of centers within some or all carpals. In the largest‐size group (39.23 ± 0.86 mm), displaying orange‐green coloration, all carpals had ossified. These observations demonstrate that during adult newt forelimb regeneration, the failure of the carpal elements to begin ossification in synchrony with other regrown skeletal parts duplicates a similar schedule of delayed mesopodial ossification which is evident during the development of the red eft's forelimb.
Size‐dependent responses to dehydration in the terrestrial slug, Limax maximus L.: Locomotor activity and huddling behavior
Authors: Welsford Ian G. , Banta Pamela A. , Prior David J. 
Published: June 2005

AbstractWhen specimens of Limax maximus L. are dehydrated alone or in groups of three or five, they exhibit an increase in locomotor activity but no increase in huddling behavior (i.e., the formation of aggregations of several slugs) when compared with hydrated animals. The extent of the dehydration‐induced increase in locomotion is a function of body size, with small and mediumsized animals (0.3–2.9 g) exhibiting significantly more activity than large animals (3.5–6.0 g). The dehydration‐induced behavioral responses of small slugs are affected by altering the rate of dehydration. Therefore, the variation in behavioral responses between L. maximus of different sizes may be due to the different rates of dehydration that they experience.
Biochemical adaptations to diving in the common murre, Uria aalge, and the Atlantic puffin, Fratercula arctica
Authors: Davis M. Benjamin , Guderley Helga 
Published: June 2005

AbstractTo evaluate whether specialized biochemical adaptations facilitate the extensive breath‐hold capacities of diving alcids, we compared several such parameters in three locomotor muscles of the common murre, Uria aalge, and the Atlantic puffin, Fratercula arctica, with those in the corresponding muscles of two terrestrial species, the pigeon, Columbia livia, and the pheasant, Phasianus colchicus. The pheasant and pigeon were chosen since they provide recognizably different patterns of biochemical support for flight. The pectoral, supracoracoideus and sartorius muscles were examined since they are the major locomotor muscles. The biochemical modifications which distinguish alcid muscles from pigeon muscles are subtle but include greater hexokinase activities in pigeon muscles, greater myoglobin levels in alcid muscles, and differences in the intraspecific ranking of the muscles' capacities for glycolysis from glycogen. By contrast, the capacities for glycolysis from glycogen, the buffering capacities, and the regulatory properties of pyruvate kinase of these muscles are similar in alcids and pigeons. We conclude that diving does not require major modifications of the overall metabolic design of muscle used by a bird which is capable of sustained aerobic flight. On the other hand, the biochemical differences between pheasants and alcids are more pronounced. Pheasant pectoral has a higher capacity for glycolysis from glycogen than any of the other muscles. Flight muscles in pheasants have higher buffering capacities than those in alcids. Clearly the glycolytic specialization of pheasant flight muscles is not shared by alcid flight muscles. Thus, we suggest that alcids do not rely upon glycolysis to any considerable extent during flight or diving.
Effects of starvation and neuroactive drugs on feeding in Caenorhabditis elegans
Authors: Avery Leon , Horvitz H. Robert 
Published: June 2005

AbstractCaenorhabditis elegans concentrates its food, bacteria, by pharyngeal pumping. The rate of pumping is affected by the presence of bacteria. Using a new assay that allows measurement of pumping rate in a population of worms suspended in liquid by measuring their uptake of microscopic iron particles, we have confirmed and quantitated this effect. Furthermore, we demonstrated that starvation stimulates pumping. Worms that had been deprived of bacteria for more than 4 hours pumped in the absence of bacteria under conditions in which well‐fed worms did not. Furthermore, starved worms responded to lower amounts of bacteria than did fed worms.The assay was also useful for measuring effects of drugs on pumping. Of about 30 chemicals screened, 5 had clear effects. The neurotransmitter serotonin and the serotonin uptake inhibitor imipramine stimulated pumping, while the serotonin antagonist gramine inhibits. Imipramine stimulation is greatly decreased in cat‐1 and cat‐4 mutants, which have low levels of serotonin. Muscimol, an agonist for the neurotransmitter GABA, and ivermectin, whose site of action may also be the GABA receptor, both inhibit pumping. Qualitative observations suggested a role for acetylcholine in the regulation of pumping.
Biochemical study of prolactin binding sites in Xenopus laevis brain and choroid plexus
Authors: Muccioli Giampiero , Guardabassi Antonietta , Pattono Paola 
Published: June 2005

AbstractThe occurrence of prolactin binding sites in some brain structures (telencephalon, ventral hypothalamus, myelencephalon, hypophysis, and choroid plexus) from Xenopus laevis (anuran amphibian) was studied by the in vitro biochemical technique. The higher binding values were obtained at the level of the choroid plexus and above all of the hypothalamus. On the bases of hormonal specificity and high affinity, these binding sites are very similar to those of prolactin receptors of classical target tissues as well as of those described by us in other structures from Xenopus. To our knowledge, the present results provide the first demonstration of the occurrence of prolactin specific binding sites in Xenopus laevis choroid plexus cells.
Further observations on the association between lipid metabolism and low embryo hatchability in eggs from young broiler birds
Authors: Yafei N. , Noble R. C. 
Published: June 2005

AbstractComparisons have been made of the lipid compositions of the yolk contents, yolk sac membrane, plasma, and liver of chick embryos at days 14 and 19 of incubation from young (23 week) and mature (35 week) hens. A reduced yolk lipid absorption displayed by embryos from the young parents at day 19 of incubation was accompanied by lower plasma and liver lipid concentrations. As shown by electron microscopy, there was an obvious reduction in cystolic accumulation of lipid within the liver. The reduced yolk lipid concentration in embryos from the young hens was associated with lower levels of plasma low‐density lipoproteins and an alteration in the relative proportions of the major plasma lipid fractions. The altered yolk, plasma, and liver lipid concentrations are discussed with respect to values for embryos from mature hens.
Comparative study on glucose‐6‐phosphate dehydrogenase from rabbit tissues
Authors: Ninfali Paolino , Palma Fulvio 
Published: June 2005

AbstractThe activity of glucose‐6‐phosphate dehydrogenase (G6PD) was measured in bone marrow, spleen, lung, liver, kidney, adipose tissue, brain, heart, muscle, and in the erythroid cell line of rabbit. In tissues, the activity ranged from 6.87 to 0.09 U/g wet tissue, found in bone marrow and muscles, respectively, whereas in the erythroid cell line it ranged from 14.3 to 2.4 U/g cells for erythroblasts and erythrocytes, respectively. The electrophoretic patterns of the tissue crude extracts shoed an identical set of three activity bands, and the immunotitration curves obtained with rat antirabbit erythrocyte G6PD antibodies shared the same equivalence point. The enzyme, purified to homogeneity from different tissues, showed no significant differences among the Km values for NADP and G6P. The results give a picture of the variability of the G6PD activity in rabbit tissues and suggest the presence of the same enzyme molecule in each tissue.
In the Mexican salamander (Ambystoma mexicanum) homozygous for the gene eyeless, unilateral neural fold rearrangements stimulate bilateral eye formation
Authors: Brun Rudolf B. 
Published: June 2005

AbstractThe objective of the present investigation was to test the hypothesis that the absence of eyes in the eyeless mutant Mexican salamander (Ambystoma mexicanum) might be caused by an antero‐posterior morphogenetic system out of balance in the head of the mutant. To test this hypothesis the antero‐posterior sequence of the neural fold of eyeless mutant neurulae was rearranged in two ways: unilateral grafting of posterior neural fold tissues from mutant donors into the anterior nasal area of mutant hosts (and vice‐versa) was performed; and in addition, the eye region of the mutant was moved into posterior temporal positions as well as shifted forward into the nasal area. The results of these experiments demonstrate that larvae homozygous for the eyeless mutant gene are capable of forming eyes in vivo following such antero‐posterior rearrangements of their neural folds. In addition, operations performed unilaterally had a bilateral effect: eye structures differentiated on the operated as well as on the unoperated side of the larvae. These results suggest that the eyeless mutant fails to form eyes because of an inhibitory effect on the optic vesicles emanating from neighboring tissues, not because of an inherent defect in the neural plate to form retina.
Ketone body and phosphoenolpyruvate formation by isolated hepatic mitochondria from Squalus acanthias (spiny dogfish)
Authors: Anderson Paul M. 
Published: June 2005

AbstractIn elasmobranchs, triglycerides are stored in the liver, which appears to be the primary site for lipolysis and oxidation of fatty acids, a major product being ketone bodies. The objective of this study was to obtain comparative information about properties of ketone body and phosphoenolpyruvate formation by liver of Squalus acanthias (spiny dogfish, a representative elasmobranch) by using an isolated hepatic mitochondrial system we have previously described for studying respiration and glutamine‐dependent citrulline synthesis. Acetate and palmitoyl‐CoA are stoichiometrically converted to ketone bodies at a rapid rate. The capability of mitochondria to convert short‐chain fatty acids to ketone bodies indicates that the previously reported inability of dogfish mitochondria to utilize short‐chain fatty acids to support respiration is not due to absence of nucleoside monophosphate kinase activity. At least two acyl‐CoA synthetase activities are present in mitochondrial extracts, one specific for acetate and another with specificity for longer‐chain fatty acids. Utilization of palmitoyl‐CoA is carnitine‐dependent and is inhibited by low concentrations of malonyl‐CoA. Pyruvate and alanine are also rapidly metabolized to ketone bodies. Phosphoenolpyruvate is formed at a significant rate from a number of substrates, including in particular aspartate and malate in the presence of α‐ketoglutarate. The osmolytes urea and trimethylamine oxide activate and inhibit, respectively, phosphoenolpyruvate formation; in contrast, these osmolytes inhibit and activate, respectively, ketone body and citrulline formation by isolated mitochondria. The results are consistent with the reported unique functions of dogfish liver in lipid metabolism and indicate that the basic enzymatic processes at the level of mitochondria appear to be analogous to those present in mammalian species.