bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of photoperiod on the rate of 3H‐thymidine incorporation of epididymal principal cells in adult Syrian hamsters
Authors: Johnson Larry , Bartke Andrzej 
Published: June 2005

AbstractPhotoperiod‐induced cycles of gonadal regression and recrudescence in the Syrian hamster were used to determine if epididymal growth in adults involves mitotic activity of principal cells. In Experiment 1, the following groups of adult hamsters were examined: induced recrudescing (5L:19D [5 hr light and 19 hr dark] for 13 wk followed by 14L:10D for at least 3 wk), spontaneous recrudescing (5L:19D for 25 wk), and active gonadal state (14:10D). In Experiment 2, adult hamsters were divided into the following groups: induced recrudescing, active, and regressed (5L:19D for 16 wk). Hamsters received subcutaneous injections of 0.5 μCi 3H‐thymidine/g body weight three times/wk for 3 wk. The epididymis was fixed in a glutaraldehyde followed by osmium, embedded in Epon 812, and sectioned at 1 μm. Slides were dipped in Kodak NTB‐3 emulsion, exposed for 2 or 3 months, developed, and evaluated for isotopic labeling of principal and basal cell nuclei by scoring 500 to 1,000 nuclei. In Experiment 1, the percentages of labeled principal cell nuclei for the induced recrudescing, spontaneous recrudescing, and active groups were 26 ± 2%, 23 ± 5%, and 9 ± 1%, respectively. Considering the intermittent availability of 3H‐thymidine during 21 days, this represents daily recruitment of 6.3%, 5.6%, and 2.2%, respectively. In Experiment 2, the percentages of labeled principal cell nuclei for induced recrudescing, active, and regressed groups were 12 ± 4%, 3 ± 1%, and 4 ± 1%, respectively. There was no effect of photoperiod on labeling pattern of basal cells (1.5 ± 0.6%, 1.2 ± 0.1%, 0.4 ± 0.1% for the three photoperiod groups, respectively). Regardless of photoperiod, there was no difference in the labeling pattern of principal or basal cells between the head and the tail of the epididymis. In conclusion, photoperiod influenced the recruitment of epididymal principal cells throughout the epididymis, and new principal cells were added continually to the existing population of cells even in gonadally active adult hamsters.
Nematocyst discharge in Hydra does not require the presence of nerve cells
Authors: Aerne Birgit L. , Stidwill Robert P. , Tardent Pierre 
Published: June 2005

AbstractBy parabiosis we have constructed Hydra that lack nerve cells but whose tentacles contain nematocytes (stinging cells). We were able to demonstrate that the nematocysts of these polyps can be triggered either mechanically or electrically. We conclude that nematocyst discharge in hydra does not require the presence of nerve cells.
Internalization of erythrocytes into liver parenchymal cells in naturally hibernating frogs (Rana esculenta L.)
Authors: Barni Sergio , Bernocchi Graziella 
Published: June 2005

AbstractMature and intact red blood cells were found in hepatocytes of frogs during natural underground hibernation. No signs of erythrophagocytosis, e.g., separating membranes between erythrocyte and hepatocyte cytoplasm, and lysosomes, were observed. Red blood cells probably penetrated into hepatocytes by ameboid‐like mechanisms, which can be deduced by cytoplasmic protrusions and invaginations. Most of the hepatocytes had large amounts of stored glycogen and few organells, often segregated in condensed areas. The narrowed bile canalicular lumens without lysosomes and exocytotic vacuoles around them and the reduction of the Disse spaces indicate a low metabolic activity of liver during natural hibernation. The dramatic accumulation of red cells in the hepatocytes of hibernating frogs could share similarities with the phenomenon of internalization of leucocytes into epithelial cells of some vertebrate's tissues via emperipolesis, the mechanisms of which are not well understood.
Adenylate cyclase activity in Mytilus galloprovincialis Lmk: Characteristics of the enzyme from mantle tissue
Authors: Mancebo M. J. , Treviño M. , Crespo C. A. , Espinosa J. 
Published: June 2005

AbstractThe presence and characteristics of a membrane‐bound adenylate cyclase from Mytilus galloprovincialis mantle tissue has been investigated. Enzymatic activity was measured using α32P‐ATP as the substrate with chromatographic isolation of the 32P‐cAMP formed. The enzyme has a Km for ATP of 0.35 mM at 20°C and requires divalent cations (Mg2+ /Mn2+) for its activity. Optimal GTP concentrations are between 10−6 M and 10−4 M. The non‐hydrolyzable GTP analogs, GTPpNHp and GTPγS, increase the activity of the enzyme two‐ to fourfold. NaF stimulates the enzymatic activity ten‐ to 20‐fold. An inhibition of basal activity by adenosine was observed.
Incorporation of strontium (90Sr2+) into the skeleton of the hermatypic coral Galaxea fascicularis
Authors: Ip Y. K. , Krishnaveni P. 
Published: June 2005

AbstractThe rate of 90Sr2+ deposition in Galaxea fascicularis was linear with respect to Sr2+ concentration (0.01–20 mM) and refractory to DCMU (1 μM), an inhibitor of photosynthesis. The deposition rate of 90Sr2+ in polyps incubated under a light intensity of 200 μE.m−2 s−2 was not significantly different from that in polyps incubated in total darkness. The deposition rate of 45Ca2+ (1–20 μM), on the other hand, exhibited saturation kinetics. In addition, it was DCMU sensitive and enhanced by light. Our results therefore support observations reported elsewhere that KsrA is inversely correlated with growth rate in reef corals. However, Sr2+ and Ca2+ deposition in G. fascicularis does not appear to involve similar biochemical mechanisms.
Renal clearance of phosphate and calcium in vitamina D‐deficient chicks: Effect of calcium loading, parathyroidectomy, and parathyroid hormone administration
Authors: Clark Nancy B. 
Published: June 2005

AbstractSerum and renal clearance values of phosphate and calcium were measured and compared in 4 week‐old vitamin D‐deficient and vitamin D‐replete chickens (Gallus gallus). D‐deficient chicks had significantly lower body weights and serum calcium values; however, their renal functions were not different from D‐replete controls. Serum calcium values in D‐deficient birds did not change in response to parathyroid hormone (PTH) administration; however, they did drop significantly in response to parathyroidectomy (PTX). Serum phosphate values of D‐deficient birds, but not D‐replete birds, rose significantly after PTX.Clearance of phosphate is known to increase after administration of PTH. This conspicuous effect was absent in PTH‐injected vitamin D‐deficient chickens. PTX caused the excretion of phosphate to drop in both D‐deficient and D‐replete birds to near zero. Conversely, PTX of both D‐deficient and D‐replete chickens stimulated the excretion of more calcium than in controls.Calcium loading elevates the fractional excretion of calcium in both D‐deficient and D‐replete birds. It also causes a decrease in phosphate excretion in both groups, presumably by inhibiting the secretion of PTH. PTH administration of D‐replete, calcium‐loaded birds caused increased phosphate excretion (as it did in normal controls), an effect that was not seen in similarly treated D‐deficient birds.Therefore most renal functions studied after calcium loading, PTH administration, or PTX are not altered by vitamin D deficiency in the chicken. The major significant finding is that vitamin D‐deficient chickens do not excrete increased amounts of phosphate in response to PTH stimulus.
Thyroid hormone stimulates the shift of erythrocyte populations during metamorphosis of the flounder
Authors: Miwa Satoshi , Inui Yasuo 
Published: June 2005

AbstractHormonal control of changes in circulating erythrocytes was studied in the metamorphosing flounder (Paralichthys olivaceus). Premetamorphic flounder larvae had large, round erythrocytes with small, round and pyknotic nuclei. At metamorphic climax, many smaller erythroid cells with larger nuclei appeared in the circulation. These cells developed into elliptical, adult‐type erythrocytes in fully metamorphosed juveniles. Larval erythrocytes were not observed in juvenile fish. Biochemical analysis of hemoglobins are different between larvae and juveniles. L‐thyroxine (T4) treatment at 100 ppb in ambient seawater clearly stimulated a precocious morphological shift in the erythrocyte populations within 15 days, while the predominant blood cells in control fish were the larval erythrocytes throughout the experiment. The erythrocyte shift found in T4‐treated larvae coincided with metamorphic changes in external appearance and behavior of the fish. These results indicate the presence of the two distinct populations of erythroid cells, larval type and adult type, in developing flounder larvae, and suggest that thyroid hormone suppresses larval erythropoiesis and stimulates establishment of adult, or definitive erythropoiesis.
Increased content of inositol phosphates in amputated limbs of axolotl larvae, and the effect of beryllium
Authors: Tsonis Panagiotis A. , English Denis , Mescher Anthony L. 
Published: June 2005

AbstractThe involvement of phosphatidylinositol phosphate (PIP) breakdown in the initiation of cell proliferation, differentiation, or other developmental processes is well established. PIP breakdown leads to the formation of second messengers, including inositol trisphosphate, which evoke cellular responses and cell‐to‐cell interactions. Such events occur very early after exposure of cells to an agonist. In an attempt to elucidate biochemical mechanisms that could be involved in stimulating cellular events during very early stages of vertebrate limb regeneration we examined local production of inositol phosphates (IPs) following amputation axolotl limbs. The content of IPs increases in stump tissues within 30 seconds after amputation. In addition we found that beryllium treatment, which inhibits regeneration if applied to stumps immediately after amputation, blocks production of IPs. Similarly, Li+ which is known to inhibit production of IP3 affected regeneration in a similar fashion to beryllium. These results indicate that production of PIP‐derived second messengers is one of the earliest events following amputation and might be crucial for the regeneration process.
Regulation of proline synthesis in osmotic response: Effects of protein synthesis inhibitors
Authors: Burton Ronald S. 
Published: June 2005

AbstractLike many euryhaline marine invertebrates, the copepod Tigriopus californicus acclimates to changes in environmental salinity by adjusting intracellular concentrations of free amino acids (FAA). Proline and alanine are the primary contributors to the FAA pool, and previous work has shown that synthesis of the former is specifically induced by hyperosmotic stress. To determine if protein synthesis plays a regulatory role in the accumulation of FAA during hyperosmotic stress, T. californicus were exposed to two protein synthesis inhibitors prior to and during transfer from 50% to 100% seawater. Both inhibitors, cycloheximide and anisomycin, were found to sharply reduce proline synthesis during hyperosmotic stress. By providing 14C‐(U)‐L‐glutamate as a proline precursor, evidence was obtained that the ultimate site of action for the inhibitors was in the three‐step pathway between glutamate and proline. This work suggests that hyperosmotic stress induces the synthesis of one or more of the enzymes in the proline biosynthetic pathway or a protein which functions to stimulate the activity of these enzymes.
Cleavage rates of diploid and tetraploid mouse embryos during the preimplantation period
Authors: Henery C. , Kaufman M. H. 
Published: June 2005

AbstractDespite the fact that spontaneous tetraploidy is a rare phenomenon in mice, such embryos may be produced experimentally by a variety of means, though only a very limited degree of postimplantation development has been achieved. Despite this apparent limitation, much data on the rate of development of preimplantation tetraploid embryos has been published. However, the findings from these studies has often been conflicting. In the light of the recent successful achievement of advanced postimplantation tetraploid development in our laboratory, we decided it was an opportune time to re‐evaluate the preimplantation development of these embryos in as near to optimal conditions as we could achieve.Three groups were studied, namely 1) control (diploid) embryos developing in vivo, 2) control (diploid) embryos that had been isolated at the 2‐cell stage, briefly retained in culture, then transferred to the oviducts of pseudopregnant recipients, and 3) tetraploid embryos produced by electrofusion of blastomeres at the 2‐cell stage, then transferred to the oviducts of pseudopregnant recipients. Embryos were isolated from females from each group at specific times after the HCG injection to induce ovulation. The total cell number of each embryo was established and the log mean values were plotted against time. From the gradients of the lines it was possible to establish that there was a significant difference between the cell doubling time of the transferred controls (group 2) compared to the in vivo controls (group 1) with cell doubling times of 15.86 ± 1.45 h and 10.27 ± 0.24 h, respectively. However, there was no significant difference between the cell doubling time of the tetraploids and the transferred controls (group 2), with the tetraploids having a cell doubling time of 14.87 ± 0.54 h. The results therefore show that under matched experimental conditions, tetraploid mouse embryos develop during the preimplantation period at the same rate as diploids despite their reduced cell number. This finding suggests that the various hypotheses that have been proposed to explain the poor postimplantation development of tetraploids, related principally to their supposed poorer proliferative activity than controls, does not appear to be applicable at least in relation to their preimplantation development.
Enzyme activities and antifungal action of fertilization envelope extract from fish eggs
Authors: Kudo Shigeharu , Teshima Chisato 
Published: June 2005

AbstractExtracts from fertilization envelopes (FE) of activated eggs of two species of fish, Plecoglossus altivelis and Tribolodon hakonensis, have been demonstrated to contain carboxymethylcellulase, carboxymethylchitinase, β‐1,3‐glucanase (or laminaranase), lichenase, xylanase, dextranase, mannase, protease, and lysozyme activities by an agar plate method. Vitelline envelope (VE) extracts in contrast had no enzyme activities. The FE extracts exerted an antifungal or fungicidal action on the fungus Saprolegnia parasitica which was isolated from the body surface of a carp with mycosis. Inhibition of hyphal growth from the mycelial pieces was time‐dependent. The VE extracts had no antifungal action. FE extracts treated with pronase exerted no antifungal or fungicidal action on S. parasitica, but trypsinized FE extracts still retained their antifungal or fungicidal effect. These results suggest that the FE may be able to protect the embryo through enzymatic activity, which is acquired after the process of cortical reaction, and may help to degrade the cell walls of potential pathogens.
Role of cryophase temperature and thermophase duration in thermoperiodic regulation of the testicular cycle in the lizard Lacerta vivipara
Authors: Gavaud Jacqueline 
Published: June 2005

AbstractTesticular activity in reptiles is controlled primarily by thermal and thermoperiodic factors; however, little is known about the relative contribution of daily heating and nightly cooling in these processes. This question was addressed in the lizard Lacerta vivipara whose cycle is characterized by a 6 month hibernation followed by a single spring spermiogenesis and a summer spermatogenesis. From the autumnal equinox on, lizards were maintained under a constant 12L/12D photoperiod and acclimated to different 24 hour thermoperiodic regimes. Treatments combined a short or a long thermophase (2 or 6 hr basking) in alternation with either a warmer (19–21°C) or a colder cryophase (3–7°C). Testicular activity was monitored by histological examination of the testis and epididymis in late December and in early March. Heat provided daily during either 2 or 6 hour phases advanced spermiogenesis and spermiation by 3–4 months. Cryophase temperatures had no significant effects on the date of onset of spermiogenesis whereas they greatly affected its speed of completion. Thus, the full testicular cycle, from one spermatogenetic wave to the next, was completed within 6 months under warmer cryophases alternating with either long or short thermophases. In contrast, only part of the cycle was completed in lizards experiencing colder cryophases since active spermiogenesis and spermiation were maintained for at least 2 months as under natural conditions. The functional significance of heat and cold per 24 hour cycles in the regulation of the testicular cycle is discussed.
Peroxisomal β‐oxidation: Insights from comparative biochemistry
Authors: Moyes Christopher D. , Suarez Raul K. , Brown Gayle S. , Hochachka Peter W. 
Published: June 2005

AbstractThe activities of fatty acyl‐CoA oxidase (FAO) and carnitine palmitoyl transferase (CPT), indices of the capacities of peroxisomal β‐oxidation and mitochondrial β‐oxidation, respectively, were determined in livers of several vertebrate species notable for differences in dietary fatty acid composition. In suckling rats FAO activities were half that in adult rats and CPT/FAO ratios twice that of adult rats. As their milk diet is dominated by medium chain fatty acids, this observation is consistent with current ideas about the role of peroxisomal β‐oxidation in rat liver in oxidation of long chain unsaturated fatty acids. In nectar‐feeding hummingbirds (fatty acids synthesized de novo) FAO activities were 50% greater than adult rats and CPT/FAO ratios onethird less than adult rats, suggesting that peroxisomal β‐oxidation is relatively more important in this species, despite a fatty‐acid‐poor diet. In marine fish (herring, dogfish shark, hagfish) FAO activities were all less than 15% that of rats and undetectable in hagfish. CPT/FAO ratios were greater in herring (8.1) and hagfish (> 30) than adult rats (3.1), suggesting that peroxisomal β‐oxidation is relatively less important in these species despite a natural diet containing high levels of long chain polyunsaturated fatty acids. These data are discussed in relation to current ideas about the role of peroxisomes in β‐oxidation of fatty acids.
Chemical repellency in birds: Relationship between chemical structure and avoidance response
Authors: Clark Larry , Shah Pankaj S. , Mason J. Russell 
Published: June 2005

AbstractWe examined how molecular structure of 24 anthranilate and benzoic acid derivatives correlated with drinking behavior in European starlings Sturnus vulgaris. The effectiveness of bird repellents was associated with basicity, the presence of an electron‐donating group in resonance with an electron‐withdrawing carboxylic group on a phenyl ring, and a heterocyclic ring in the same pi cloud plane as the phenyl ring. Of the benzoic acid derivatives tested in this study, methyl, ethyl, dimethyl, and linalyl anthranilate as well as anthranilic acid and 4‐ketobenztriazine were repellent to birds. Water consumption was significantly reduced relative to control levels at concentrations as low as 0.05% (weight/volume) for the best repellents. Further statistical tests showed that reduction in consumption for the best repellents was absolute, not significantly different from zero consumption. Anthranilic acid isomers were moderately good repellents. The ability to generate a model predicting repellency allows for the efficient identification and development of ecologically sound, nonlethal, taxa‐specific repellents to be used for the protection of wildlife in agricultural and industrial applications.
Genetic analysis of androgenetic rainbow trout
Authors: Scheerer Paul D. , Thorgaard Gary H. , Allendorf Fred W. 
Published: June 2005

AbstractWe analyzed a number of genetic characteristics in androgenetic rainbow trout (Oncorhynchus mykiss) and their progeny. The androgenetic progeny of individual androgenetic males appeared genetically identical to each other based on eight enzyme loci. Their viability was no higher than that of androgenetic progeny of outbred males. Homozygous androgenetic female rainbow trout produced very poor quality eggs. When common eggs and sperm from outbred individuals were used to produce androgenetic and gynogenetic progeny, the yield of gynogenetic progeny was higher but some were heterozygous at protein loci, while no androgenetic progeny were heterozygous. Some androgenetic diploid rainbow trout were successfully produced from cryopreserved sperm. The progeny of some androgenetic males crossed to normal females were virtually all males, while the progeny of other males were virtually all females. This suggests that both XX and YY androgenetic individuals may develop as males. Androgenesis is likely to be useful for generating homozygous clones for research and for recovering strains from cryopreserved sperm.
Proliferation of lymphocyte‐like cells from the solitary tunicate, Styela clava, in response to allogeneic stimuli
Authors: Raftos D. A. , Cooper E. L. 
Published: June 2005

AbstractLymphocyte‐like hemocytes (LLCs) of solitary tunicates proliferate in response to allogeneic stimuli. In vitro labeling of proliferative hemocytes from the solitary species Styela clava revealed significantly greater proliferative activity among individuals immunized with allogeneic tissue as opposed to autogeneically primed and naïve animals. Enhanced proliferation was restricted to discrete crypts of dividing cells within the body wall of recipients. Here, increased proliferative activity was specifically associated with LLCs. These data support previous results which implicated LLC activity with immunological memory that is evident in allograft rejection. Hence, it is postulated that adaptive histoincompatibility responses in solitary tunicates depend upon the specific proliferation of immunocompetent cells.
On the convergent cell movements of gastrulation in Fundulus
Authors: Trinkaus J. P. , Trinkaus Madeleine , Fink Rachel D. 
Published: June 2005

AbstractMainly because of its transparency, the Fundulus gastrula constitutes ideal material for direct study of morphogenetic cell movements in vivo. Marking studies show that deep cells of the germ ring converge toward and enter the embryonic shield, where they undergo extension. Those close to the shield move faster. Analysis of videotapes reveals that all deep cells of the dorsal germ ring move toward the shield. But none moves in a direct line. All meander considerably. Germ ring cells nearer the shield move toward it at a higher net rate than those farther away because they meander less. This suggests that exogenous factors promote their directionality. Cells in the prospective yolk sac adjacent to the germ ring also show net convergence, but they meander more. Directional forces are apparently stronger in the germ ring.Converging deep cells move both by filolamellipodia and, less frequently, by blebs. However, there is very little individual cell movement; all cells are almost always in adhesive contact with other cells in moving cell clusters. Clusters vary constantly in size, continually aggregating with other cells and other clusters and splitting. Filolamellipodial cells show contact inhibition of cell movement. Nevertheless, they move and do so directionally, presumably in part because, as members of cell clusters, much of their movement is passive. They also show intercalation or invasive activity, but, consistent with their contact‐inhibiting properties, only when neighboring cells separate and provide free space. Cells moving by blebbing locomotion are non‐contact inhibiting and intercalate readily. Cell division continues during convergence. Although this temporarily arrests their movement, the daughter cells soon join in the mass convergent movement.