bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic low humidity‐stress in the lizard Anolis carolinensis: Effects on ovarian and oviductal recrudescence
Authors: Summers Cliff H. 
Published: June 2005

AbstractAnoline lizards, such as Anolis carolinensis, live in humid regions of the Americas and reproduce during the rainy seasons or when sufficient moisture is available. The present experiment was undertaken to elucidate the effect of low relative humidity on ovarian and oviductal recrudescence in A. carolinensis. The experiment was done in January, when ovaries and oviducts are quiescent. Warm temperatures and long photophase (14L32°C: 10D20°C) elicited ovarian and oviductal growth in lizards kept under high relative humidity (>80%). Chronic low humidity (<35%), however, severely retarded ovarian growth in lizards treated with stimulatory temperature and light. Although the ovaries grew slightly, oviductal growth was completely blocked by low humidity. These results suggest that low humidity may be an environmental cue for A. carolinensis, signalling low available moisture and inappropriate conditions for reproduction.
Evidence suggesting a role for sperm metalloendoprotease activity in penetration of zona‐free hamster eggs by human sperm
Authors: Díaz‐Pérez Eneida , Thomas Paul , Meizel Stanley 
Published: June 2005

AbstractIt has been reported that metalloendopotease (MEP) activity is involved in somatic cell membrane fusion events and in the sea urchin sperm acrosome reaction (AR). MEP activity also has been demionstrated in human and other mammalian sperm. The present study was concerned with investigating whether a human sperm MEP is important in membrane events necessary for sperm egg fusion. Ejaculated human sperm were washed, capacitated in vitro, and preincubated with the competitive MEP inhibitors phosphoramidon (50 μM) or CBZ‐L‐phenylalanine (1 mM), with 100 μM diethylenetriaminepentaacetic acid (DTPA), a heavy metal chelator, or as controls, with the appropriate solvents. The AR was initiated in vitro with preovulatory human follicular fluid and the sperm washed to dilute inhibitors and then coincubated with zona‐free golden hamster eggs (zonae and cumuli removed with trypsin and hyaluronidase, respectively). Eggs were washed after 0.5 h, and the number of sperm remaining bound was counted. After 2.5 h further incubation, the eggs were stained with acetolacmoid or acetoorcein and penetration was assayed by counting the number of decondensed sperm heads per egg (penetration index) and the percent of penetrated eggs. The inhibitor treatments did not decrease the percentage of penetrated eggs (range 80–90%), but a significant reduction in the penetration index was observed. Phosphoramidon reduced the penetration index by 45%, CBZ‐L‐phenylalanine by 57%, and DTPA by 56%. None of the inhibitors decreased the penetration index or the percentage of penetrated eggs when added directly to suspensions of acrosome‐reacted sperm and zona‐free eggs at the diluted levels that would have been present after washing inhibitor‐treated sperm. Other studies demonstrated that the MEP inhibitors did not inhibit sperm motility, sperm binding, the occurrence of the AR, the loss of acrosomal matrix and AR vesicles, or sperm head decondensation. Phosphoramidon also significantly decreased the penetration index when the AR was initiated by the calcium ionophore ionomycin. These results suggest that during the AR, a human sperm MEP is involved (directly or indirectly) in modifying the sperm plasma membrane so as to increase its potential for fusion with the egg plasma membrane.
Effects of cyclic AMP on the spontaneous meiotic maturation of cumulus‐free bovine oocytes cultured in chemically defined medium
Authors: Homa Sheryl T. 
Published: June 2005

AbstractThe rate of spontaneous meiotic maturation and the period of commitment to this process were determined in bovine oocytes devoid of surounding cumulus cells, cultured in chemically defined medium with bovine serum albumin in the absence of serum. The effects of compounds that are known to elevate levels of intracellular cyclic adenosine monophosphate (cAMP) on the resumption and progression of meiosis were investigated. Bovine oocytes were mass‐harvested, dended of cumulus cells, and cultured in 2A‐BMOC medium supplemented with 0.5% bovine serum albumin. Intracellular cAMP levels were indirectly modified using 8‐bromo‐cAMP, bibutyryl cAMP (dbcAMP), forskolin, or 3‐isobutyl‐1‐methyl xanthine (IBMX). Meiotic maturation was scored cytogenetically. Ninety percent of denuded bovine oocytes mature after 24 h, with 65% progressing beyond anaphase I. These oocytes remain at the germinal vesicle (GV) stage for up to 8 h in culture. GV breakdown (GVBD) occurs in 40.5% of oocytes at 9 h. The peak times for the different meiotic stages were 12 h for diakinesis, 15 h for late diakinesis to metaphase I, 20 h for metaphase I, and 24 h for telophase I. By 48 h, most had reached metaphase II. There is a 2‐h lag period between the time at which they become irreversibly committed to mature (at 7 h) and when they demonstrate GVBD (at 9 h). Incubation for 12 h with high concentrations for 8‐bromo‐cAMP and forskolin significanly inhibited GVBD, while the effect of dbcAMP was similar but less pronounced. By 24 h, most of the control and dbcAMP‐treated oocytes were at anaphase I or beyond, while the majority of oocytes treated with 8‐bromo‐cAMP or forskolin had only progressed to metaphase I. Prolonged cultures for 44 h revealed no significant difference in the proportion of treated oocytes reaching anaphase I. to metaphase II compared with controls. IBMX inhibited GVBD in a dose‐dependent manner following 24‐h cultrue, and at low concentrations its effects was similar to that observed for high concentration of 8‐bromo‐cAMP and forskolin. The timing of observation is thus crucial for interpreting the effects of these compounds on bovine oocyte maturation. The results suggest that elevation of intracellular cAMP induces a transitory inhibition of bovine oocyte GVBD. Although the bovine oocyte plasma membrane contains adenylate cyclase, it may also possess an active phosphodiesterase that could prevent dbcAMP and forskolin from raising intracellular levels of cAMP suffeciently to maintain meiotic arres for any considerable time. As 8‐bromo‐cAMP is only partially hydrolyzed by phosphodiesterase, there may be more of this analogue available to stimulate cAMP‐dependent protein kinase, which could account for the more pronounced effect observed with 8‐bromo‐cAMP compared with dbc‐AMP.
Acidic macromolecules associated with the mineral phase of scleractinian coral skeletons
Authors: Constantz Brent , Weiner Stephen 
Published: June 2005

AbstractMacromolecules intimately associated with the mineral phase of two species of scleractinian coral skeletons are extracted in different ways and partially characterized in some detail for the first time. They are shown to contain an assemblage of glycoproteins in which the protein moiety is rich in acidic amino acids and the carbohydrate moiety contains sulfated polysaccharides. In the presence of calcium, the proteins partially adopt the β‐sheet conformation. The properties of these macromolecules are all consistent with their fulfilling some as yet unidentified roles in controlling mineralization. Furthermore, their properties are similar in many respects to macromolecules present in the mineralized tissues of diverse organisms.
Effects of some β‐carbolines on the concentrations of 5‐hydroxytryptamine, dopamine, and some related metabolites in the cerebral ganglia of the cockroach (Periplaneta americana)
Authors: Sloley B. Duff 
Published: June 2005

AbstractThe effects of the β‐carbolines, harmaline, harmalol, harmane, and harmine on 5‐hydroxytryptamine, dopamine, and tryptophan concentrations in the cerebral ganglion of the cockroach (Periplaneta americana) were investigated. Injection of harmaline and harmine‐induced decreases in the concentrations of 5‐hydroxytryptamine and dopamine. The 5‐hydroxytryptamine depletion was greater than the dopamine depletion. Injections of harmalol had no effect. Tryptophan concentrations were variable, although significant decreases were observed in harmaline‐treated animals. N‐acetyl 5‐hydroxytryptamine, 5‐hydroxyindoleacetic acid, and 5‐hydroxytryptophan remained below the level of detection in all tissues examined, indicating that these compound do not accumulate within the central nervous system as a result of the various treatments.
Lipoproteins I and II from the hemolymph of the blue crab Callinectes sapidus: Lipoportein II associated with vitellogenesis
Authors: Lee Richard F. , Puppione Donald L. 
Published: June 2005

AbstractTwo different high density lipoproteins were isolated and characterized in the hemolymph of blue crabs (Callinectes sapidus). Lipoprotein I was found in both sexes and comprised one peptide (112,000 daltons) and lipid, primarily phosphtidyl choline. Lipoprotein I properties included a hydrated density of 1.12 g/ml, sedimentation coefficient of 5.4 Svedberg flotation units and a protein to lipid ratio of 1.0. This lipoprotein is assumed to have a role in transporting lipid from the hepatopancreas to other tissues. Lipoprotein II had three peptides (190,000, 107,000 and 78,000 daltons), phosphatidyl choline as the major lipid, a hydrated density of 1.16 g/ml, a sedimentation coefficient of 10.4 Svedberg flotation units, a protein to lipid ratio of 1.1, and a yellow to orange color due to a mixture of carotenoids. Lipoprotein II was found only in female crabs undergoing vitellogenesis. Lipoprotein II appeared after 30 days in females that had mated and completed their final molt. The maximum concentration was reached in 50 to 60 days. Lipoprotein II was not present in recently molted females in a collection of crabs from one esturine river but was present in all other stages with highest concentrations (up to 8 mg/ml hemolymph) in stages 5 and 6 (females with large, well developed ovaries). Crab ovaries had a lipoprotein similar to hemolymph Lipoprotein II. Lipoprotein II probably plays an important role in carrying lipid and specific peptides to ovarian tissues. Crustacean hemolymph lipoproteins show some similarities to insect lipophorins, but are quite different from vertebrate lipoproteins.
Nuclear transplantation of rat embryos
Authors: Kono T. , Shioda Y. , Tsunoda Y. 
Published: June 2005

AbstractThe nuclei from one‐, two‐, four‐, and eight‐cell rat embryos were transferred into enucleated zygotes and development to term of the reconstituted embryos, after transfer to recipients, was examined. The rate of electrofusion of enucleated zygotes with karyoplasts was quite high (81–92%), but the fusion rate was only 8% when Sendai virus (HVJ) was used. A large percentage of the enucleated zygotes that received pronuclear karyoplasts developed to the two‐cell stage in vitro (89%) and to term (22%) after transfer to recipient rats. Although 67%, 57%, and 67% of enucleated zygotes receiving nuclei from two‐, four‐ and eight‐cell embryos, respectively, developed to the two‐cell stage, they failed to develop to term after transfer.
Effects of teratogenic antibodies on cultured visceral yolk‐sac endodermal cells: Cytotoxicity and morphological studies
Authors: Cheewatrakoolpong Boonlert , Leung Christopher C. K. 
Published: June 2005

AbstractPrimary cultures of visceral yolk‐sac (VYS) endodermal cells were used to assess the effects of teratogenic and nonteratogenic antibodies. When assessed by cytotoxicity assay, teratogenic antibodies appeared to be lethal to the cultured cells at high concentrations (1.25‐5 mg of antibodies per ml of culture medium). At a nonlethal dosage, the teratogenic antibodies induced morphological changes, including retraction and rounding up of living cells. The cytotoxic effect as well as the effect on cell morphology appeared to be dose‐dependent and specific to VYS endodermal cells. The mechanisms of cell killing were not the same as those attributed to complement‐mediated cell lysis. The nonteratogenic antibodies did not have any cytotoxic effect nor did they cause any cell morphological alterations. The results of this investigation, when interpreted by correlating the dose‐dependent effects of the teratogenic antibodies on cultured endodermal cells with the in vivo teratogenic effect, suggest that teratogenic antibodies when given at a teratogenic dose cause congenital abnormalities without killing the VYS endodermal cells.
Tilapia prolactin stimulates estradiol‐17β synthesis in vitro in vitellogenic oocytes of the guppy Poecilia reticulata
Authors: Tan C. H. , Wong L. Y. , Pang M. K. , Lam T. J. 
Published: June 2005

AbstractOocytes at different stages of growth were isolated from the guppy and incubated with and without increasing doses (0.01 to 1000 ng/ml) of a tilapia prolactin (tPRL188). Measurement of the estradiol‐17β secreted into the medium showed that estrogen synthesis from endogenous precursors was stimulated by tPRL at all stages of oocyte growth. In all cases, the maximal stimulating dose was 1 ng/ml. At this dose, the magnitude of the stimulation in estradiol‐17β synthesis was greatest (77%) in oocytes at the beginning of vitellogenesis. These results strongly suggest a role of prolactin in ovarian steroidogenesis of the guppy, and it is possible that this action of prolactin constitutes an additional control mechanism regulating estrogen synthesis in the fish.
DNA synthesis in the mouse blastocyst during the beginning of delayed implantation
Authors: Given Randall L. 
Published: June 2005

AbstractThe spatiotemporal pattern of DNA synthesis in the mouse embryo at the beginning of metabolic dormancy was examined. Embryos were recovered from females at intervals following ovariectomy at 1100 hours on day 4 of pregnancy, incubated in vitro for 1 h in the presence of [3H]thymidine, and prepared for light microscopic autoradiography. The proportion of labeled cells in the embryo remained high (40–60%) for 18 h after ovariectomy and then declined gradually to 12% by 96 h. However, analysis of individual cell subpopulations showed that the decline was not uniform in all regions of the blastocyst. Labeling was high over the inner cell mass (ICM) during all time intervals in the study, while labeling over the mural trophoblast cells declined sharply by 24 h after ovariectomy. Labeling over the polar trophoblast also declined but had values that were intermediate between the ICM and mural trophoblast regions of the blastocyst. These regional differences in DNA synthesis during the arrest of development suggest that intermediate steps are involved in control of DNA synthesis in the embryo and that the ICM may play a role in the different responses of the trophoblast cell populations.
Ultrastructural localization of RFamide‐like peptides in neuronal dense‐cored vesicles in the peduncle of Hydra
Authors: Koizumi Osamu , Wilson Jeff D. , Grimmelikhuijzen Cornelis J. P. , Westfall Jane A. 
Published: June 2005

AbstractThe presence of Arg‐Phe‐amide (RFamide)‐like peptides in dense‐cored vesicles in neurons of the peduncle of Hydra was demonstrated by immunogold electron microscopy. Thin sections of Lowicryl‐embedded tissue labeled with antisera to RFamide and 5‐nm gold‐conjugated, secondary antibody and of Epon‐Araldite‐embedded tissue labeled with 15‐nm gold particles revealed a concentration of RFamide‐like immunoreactivity over the granular cores of vesicles in epidermal ganglion cells. Gold‐labeled, dense‐cored vesicles were present in the perikaryon, long thin neurites, and axon terminals of these neurons. The aggregation of labeled dense‐cored vesicles in an axon terminal on the myoneme of an epitheliomuscular cell suggests a possible function of RFamide‐like peptides in neuromuscular transmission. Gold staining of dense‐cored vesicles completely disappeared when the RFamide antiserum was preabsorbed with 10 μg/ml RFamide. These results are the first demonstration that the dense‐cored vesicles of Hydra neurons contain a neuropeptide.
Ability of various injuries to promote resorption of denervated, nerve independent regenerates of adult newts
Authors: Winner Cherie Olsen 
Published: June 2005

AbstractYoung blastemas of the newt resorb if the limb is denervated, and are thus called “nerve dependent.” Late bud and later stage regenerates are termed “nerve independent” because, while denervation inhibits their growth, they proceed through differentiation to form a normally patterned regenerate. Schotté and Liversage ('59) found that reamputation of a denervated nerve independent regenerate causes it to resorb. The present study asked whether injuries of varying severity are equally effective at promoting resorption. Newt forelimbs were amputated through the mid‐radius/ulna. At nerve independent stages, the regenerates were denervated and injured in one of a variety of ways, then monitored for signs of resorption. Reamputation of the tip or incisions which created large gaps in the wound epidermis promoted resorption in 77–90% of the cases. Histology showed that the tissue removed by tip reamputation was a small proportion of the entire regenerate, suggesting that blastema resorption is not determined simply by the number of cells directly affected by the injury. Pin prick injuries, which created small disruptions of the wound epidermis, never caused resorption. Devascularization, caused by severing the brachial artery, promoted resorption in 17% of cases. These results are not consistent with the hypothesis that avascularity is a major causative factor in nerve dependence.
Role of the mouse visceral yolk sac in nutrition: Inhibition by a somatomedin inhibitor
Authors: Balkan Wayne , Phillips L. S. , Goldstein Steven , Sadler T. W. 
Published: June 2005

AbstractA low molecular weight somatomedin inhibitory serum fraction (SI), obtained from streptozotocin‐induced diabetic rats, causes morphological abnormalities and growth reduction in mouse embryos grown in whole embryo culture (WEC). These abnormalities are thought to be caused, at least in part, by a failure of the visceral yolk sac (VYS) to properly degrade proteins, a process that normally provides the conceptus with amino acids and peptides for de novo protein sythesis (histiotrophic untrition). To test this hypothesis, embryos exposed to the SI were provided with a mixture of ten essential amino acids (supplemented group) in an attempt to circumvent SI‐induced VYS dysfunction. Results showed that 82.4% (14/17) of embryos in the amino acid‐supplemented group exhibited improved growth and development compared to those embryos exposed to medium containing the SI alone (unsupplemented group). Supplemented embryos showed greater expansion of the brain regions, improved visceral arch development, and increased protein content compared to nonsupplemented SI‐treated embryos. However, these parameters were still reduced compared to controls. VYSs from both the unsupplemented and amino acid‐supplemented groups were identical with respect to alterations in morphology and increased protein content compared to VYSs from conceptuses cultured in control medium (with or without amino acid supplementation). The improvement in embryonic growth and development due to amino acid supplementation in spite of VYS abnormalities supports the hypothesis that nutritional deprivation is one aspect of SI‐induced teratogenesis.
Mammalian limb bud development: In situ fate maps of early hindlimb buds
Authors: Muneoka Ken , Wanek Nancy , Bryant Susan V. 
Published: June 2005

AbstractFate maps of the developing mouse hindlimb bud have been constructed for the first time using exo utero surgical techniques and carbon particle injections. Such fate maps demonstrate that the limb develops in a proximal to distal manner as a result of distal expansion. The anterior‐posterior extent of the limb bud develops asymmetrically with the posterior half giving rise to slightly more of the digit pattern (digits 3–5) than the anterior half (digits 1 and 2). We found no evidence for the occurrence of extensive cellular rearrangements during limb development, and the free limb bud appears to give rise to only zeugo‐and autopodial elements with the stylopod arising in the body wall proximal to the bud. These results are consistent with our current understanding of limb development in lower vertebrates and also provide detailed information that will be useful for future limb studies in mammals.
The involvement of thyroxine and daylength in the development of photorefractoriness in European starlings
Authors: Dawson A. 
Published: June 2005

AbstractThyroidectomized starlings on long days do not become photorefractory. Four experiments were done to investigate the roles of thyroxine and daylength in the development of photorefractoriness. 1) Pharmacological doses of thyroxine administered to thyroidectomized starlings on long days induced photorefractoriness and molt, whereas the same treatment to birds on short days was ineffective. 2) Maintenance of intact starlings on a daylength long enough to cause full gonadal maturation but not quite long enough to induce photorefractoriness caused no progression toward photorefractoriness; subsequent gonadal regression after transfer to long day days occurred at the same rate as in intact birds transferred directly from short days to long days. 3) In thyroidectomized birds held on long days and then treated with thyroxine, gonadal regression occurred at the same time as in thyroidectomized birds held on short days and then treated with thyroxine while simultaneously being transferred to long days. 4) Thyroidectomized birds held on long days and treated with different doses of thyroxine became photorefractory at the same rate. These results demonstrate that thyroxine does not drive the process leading to photorefractoriness. For photorefractoriness to occur there has to be a temporal coincidence of daylength in excess of a critical daylength and the presence of thyroxine; thyroxine specifically permits the process to respond appropriately to ambient daylength.
Hydrogen sulfide oxidation by abundant nonhemoglobin heme compounds in marine invertebrates from sulfide‐rich habitats
Authors: Powell Mark A. , Arp Alissa J. 
Published: June 2005

AbstractSeveral animals from hydrogen sulfide‐rich marine habitats were found to contain unusual heme compounds (hematins) at levels of up to 10 mM; these hematins catalyzed the oxidation of sulfide and may protect the animals from sulfide poisoning. Freshly captured specimens of the echiuran worm Urechis caupo contained 0–10 mM hematin in their coelomic fluid. This hematin was present within coelomocytes in addition to 0.5–2 mM hemoglobin present in these cells as a functional oxygen‐binding hemoprotein. The hematin was present in granules, and was not associated with a globin, cytochrome, or other protein known to have a heme prosthetic group. The hematin catalyzed oxidation of hydrogen sulfide. Further studies revealed that similar hematins were present in gill tissues of bivalve molluscs, which harbor vast numbers of endosymbiotic sulfur bacteria. Hematin was found at 1.0 mM, in addition to 0.1 mM hemoglobin, in the gill tissue of the clam Solemya reidi. Hematin was also found at 1–2 mM in gill tissue of two other clams, Calyptogena magnifica and Lucinoma annulata, in addition to < 0.4 mM hemoglobin. These clam hematins also appeared to be catalysts of sulfide oxidation.