bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cholesterol turnover and ecdysone content in tissues of normal and de‐eyestalked crabs (Cancer antennarius)
Authors: Vensel William H. , Spaziani Eugene , Ostedgaard Lynda S. 
Published: June 2005

AbstractGroups of male intact, premolt and postmolt crabs, and those induced into premolt by de‐eyestalking (DE), were injected with [14C]cholesterol and selected organs were removed 24 hr later. Total as well as labeled cholesterol were measured. Values were corrected for handling loss and for extracellular (inulin) tissue volumes. Gonad had the highest endogenous cholesterol concentration (∼ 3 mg/gm), followed in order by Y organs (∼ 2 mg/gm), hypodermis, hepatopancreas, muscle, and hemolymph. Significant differences between stages for any tissue were no more than 2‐fold. However, specific activity (radioactivity/unit weight total cholesterol) of Y organs in intact premolts was 2‐ to 9‐fold higher than other organs in the same group. Shortly after DE (24 hr), Y organ specific activity was elevated as much as 164‐fold over other tissues of this group, 26 × above premolt Y organs and up to 114 × higher than Y organs of other stages. Qualitatively, similar increases occurred in hepatopancreas after DE and in muscle and hypodermis in early postmolt. The combined data include the demonstration that very rapid turnover of the free cholesterol pool occurs in Y organs in earliest premolt. Further, the large uptake of cholesterol by Y organs occurred against a steep cholesterol gradient, indicating active transport into Y‐organ cells.With the lower detection limit at 20 ng (HPLC), ecdysone was found in all tissues extracted, 20‐hydroxyecdysone only in hemolymph and hepatopancreas. Y organs contained the highest concentrations of ecdysone and contained the hormone in more stages than other tissues. No ecdysone could be detected in Y‐organs 24 hr after DE, but it was accumulated progressively with time to 45 days after DE. Together with the findings on cholesterol, these data indicate that Y organs in early premolt rapidly take up and convert sterol precursor accompanied by equally rapid secretion, without accumulation, of ecdysone.
Relationship between insecticide‐induced short and wry neck and cervical defects visible histologically shortly after treatment of chick embryos
Authors: Wyttenbach Charles R. , Hwang Julia D. 
Published: June 2005

AbstractIn order to clarify the anatomical precursor of short and wry neck, 48‐hr chick embryos were injected with 6.25–200 μg of the organophosphate (OP) insecticide diazinon and recovered either at 96 hr for histological evaluation or at 19 days for gross observation. Among embryos recovered at 96 hr, all receiving a dose of 25–200 μg showed, in serial cross sections, the cervical notochord severely folded in the vertical, horizontal, and diagonal planes and the adjacent neural tube variously folded (often with branching of its canal), deformed by the notochord, rotated, and/or displaced from the midline. Virtually all embryos injected with 6.25 or 12.5 μg were fully free of such abnormalities. The coinjection of 2‐pyridinealdoxime methochloride (2‐PAM, which protects the embryo from certain OP insecticide‐induced teratisms) along with 200 μg of diazinon markedly reduced the notochord and neural deformations caused by diazinon alone. The occurrence of short neck but not wry neck at 19 days paralleled the 96‐hr cervical histology: pronounced in all embryos receiving ⩾25 μg, virtually nonexistent in those receiving 6.25 or 12.5 μg. Though more marked at higher doses, wry neck occurred to varying extents at all doses, 6.25‐100 μg. We conclude that 1) the primary insecticide effect is upon the notochord rather than the neural tube, 2) short neck is a direct consequence of notochord folding, 3) wry neck is apparently not linked with notochord folding, and 4) vertebral fusion is not the consequence solely of muscle paralysis as argued elsewhere. We propose that the notochord folds because diazinon disrupts normal formation of its sheath.
Localization of NaK ATPase activity in the nautilus siphuncle
Authors: Greenwald L. , Verderber Gustav , Singley Carl 
Published: June 2005

AbstractThe siphuncle of the chambered nautilus (Nautilus spp) can transport cameral liquid against osmotic pressure gradients, and is presumed to be able to transport against hydrostatic pressure gradients. It is hypothesized that the mechanism of such transport involves “local osmosis” in which the siphuncle actively trasports sodium into the blind‐ended sacs of the siphuncle cells' basolateral labyrinth. This study supports this hypothesis since NaK ATPase activity was localized only over the membranes of the labyrinth. The appearance of the reaction product required potassium and was inhibited by ouabain, a specific inhibitor of the NaK ATPase.
Intercellular junctions between the follicle cells and oocytes of Xenopus laevis
Authors: Browne Carole L. , Werner William 
Published: June 2005

AbstractDuring development, the oocytes of Xenopus laevis establish junctional contact with the follicle cells enveloping them. These junctions have alternatively been described as desmosomes and as gap junctions. In this paper the morphology of these junctions has been examined in gonadotropin‐stimulated and ‐unstimulated animals at all stages of development. Contact between the oocyte and follicle cell plasmamembranes is visible in stage I oocytes as thickenings in the membranes, separated by intercellular spaces of 20nm or greater. By stage III in unstimulated oocytes and stage II in gonadotropin‐stimulated oocytes, intermembrane spaces at these junctional contacts are often reduced to 2 to 7 nm in width. These narrow intermembrane spacespersist through early stage IV, with greater frequency of occurrence in oocytes taken from hormonally stimulated animals. The closeness of these junctional contacts, and the permeability of the junctional spaces to intercellular tracer substances, supports the evidence that these are gap junctions.
Shell characteristics of eggs laid at 2,800 M by hens transported from sea level 24 hours after hatching
Authors: Leon‐Velarde F. , Whittembury J. , Carey C. , Monge C. 
Published: June 2005

AbstractNo significant differences in eggshell conductance and permeability to gases, pore area, shell thickness, or egg mass were found when eggs laid by hens transported to 2,800 m as 1‐day‐old chicks were compared to eggs laid by the parental stock at sea level. These results fail to confirm findings of Rahn et al. ('82) which suggested that alterations of eggshell structure could be associated with changes in barometric pressure.The conductance to gases (G) of the avian eggshell is a function of the sizes and numbers of pores through the shell (Ap) and shell thickness (L) (Ar et al., '74). The average values of Ap and L characteristic of each species are thought to result from rigorous natural selection, since they control the rates of gaseous exchange between the embryo and its environment and influence its survival to hatching (Ar and Rahn, '80). The average conductance to water vapor (G) of eggs laid by montane populations of wild birds and acclimatized domestic fowl is significantly decreased below sea level values in approximate proportion to the decreased in barometric pressure (PB) at each collecting location (Wangensteen et al., '74; Rahn et al., '77; Carey et al., '83; Leon‐Velarde et al., '84). The decreased conductance is considered to be important for embryonic survival at high altitude since it appears to offset the increased tendency of water vapor to diffuse from the egg at low PB and to result in rates of water loss that are independent of PB in at least one species (Carey et al., '83).
An elevated content of a unique lipid in dystrophic chicken embryonic myoblast membranes
Authors: Kester Mark , Privitera C. A. 
Published: June 2005

AbstractA unique lipid, ethanolamine plasmalogen, is not only present abnormally in the plasmalemmae of erythrocytes from ex ovo dystrophic chickens but is also present abnormally in the membranes from embryonic myoblasts of in ovo dystrophic chickens.
ATP and the autonomy of the contractile vacuole in Amoeba proteus
Authors: Pothier F. , Couillard P. , Forget J. 
Published: June 2005

AbstractContractile vacuole function in amoebae treated with immobilizing (5 mM) and nonimmobilizing (0.125 mM) concentrations of ATP has been studied. In ATP‐immobilized amoebae, most vacuolar parameters are accelerated, especially the rate of output which passes from 30 to 70 μm3/sec. This favors the concept of an autonomous vacuole, fully functional in the absence of any bulk contribution to it from remote points of the cell. A lower concentration of ATP (0.125 mM), which does not inhibit movement, causes a still greater acceleration of vacuolar function. Work is in progress to elucidate the site and mode of action of exogenous ATP on Amoeba.
Bright light flashes of 0.5 milliseconds reset the circadian clock of a microchiropteran bat
Authors: Joshi Dilip , Chandrashekaran M. K. 
Published: June 2005

AbstractA phase response curve for the circadian rhythm in the flight activity of the cave dwelling bat, Hipposideros speoris, constructed with 0.5‐msec light flashes of very high intensity reported here is the first of its kind for any mammalian system and is unlike any other phase response curves constructed for other nocturnal mammals.
Intra‐ and interspecies transfer of endosymbionts in Euplotes
Authors: Fujishima M. , Heckmann K. 
Published: June 2005

AbstractFresh water Euplotes species with a “9 type 1 pattern” of frontoventral cirri (E. patella type) depend upon symbiotic bacteria that live in their cytoplasm. Aposymbiotic cells of these species are unable to divide and eventually die if not reinfected in time. We have investigated 1) whether two types of bacterial symbionts found in stocks of E. aediculatus can replace each other and 2) whether the ability to divide can be restored for aposymbiotic cells, not only by their own endosymbionts, but also by endosymbionts of other Euplotes species. We reinfected aposymbiotic cells by injecting symbiont‐containing cytoplasm into them. The results show that the two types of symbionts found in E. aediculatus stocks can replace each other. This allows us to interpret the type 7 symbiont as a secondary invader that has displaced the original omikron‐like symbiont in some E. aediculatus stocks. Finding that the symbionts of E. woodruffi are able to support growth of E. aediculatus and that those of E. plumipes support growth of E. eurystomus suggests that all Euplotes species with a 9 type 1 cirrus pattern have the same deficiency with respect to cell division. The deficiency is best explained by assuming that it is caused by a hereditary defect that arose long ago in the common ancestor of this group of species. That many of the donor‐recipient combinations we tried did not lead to a resumption of growth and cell division of the recipients probably reflects secondary adaptations of the endosymbionts to the cytoplasm of their host species, so that they no longer have the ability to grow in other environments.
Thermal hysteresis antifreeze proteins in the midgut fluid of overwintering larvae of the beetle Dendroides canadensis
Authors: Duman John G. 
Published: June 2005

AbstractFreeze‐susceptible insects (those that die if frozen) must lower the freezing and supercooling points of their body fluids in winter. Although it is well known that many overwintering insects concentrate antifreezes such as polyols (glycerol, sorbitol, etc.) and/or thermal hysteresis proteins in the hemolymph, antifreezes have not previously been found in gut fluid.Overwintering freeze‐susceptible larvae of the Pyrochroid beetle Dendroides canadensis accumulated glycerol, sorbitol, and thermal hysteresis proteins (THPs) in the hemolymph. Although polyols were not found in the midgut fluid, THPs began to be accumulated in the autumn, and in midwinter THP levels were the same in midgut fluid and hemolymph. Midgut THP concentrations decreased in late April, and THPs were gone from the midgut by June. This seasonal increase in THPs is thought to be partially responsible for the decrease in the supercooling point of midgut fluid from ∼ −5°C in summer to ∼ −25°C in winter, although cessation of feeding in winter is also likely to be important.Proteolytic enzyme activities were at least as high in January as in June, and the THPs appear to be somewhat susceptible to these midgut enzymes, thus raising the question of how THPs are concentrated and maintained in their presence. One possible answer is that the enzymes are extremely temperature sensitive and that temperatures above 25°C are required for high levels of activity.
Lens‐forming transformations in the outer cornea of larval Xenopus laevis induced by implanted spinal ganglia
Authors: Filoni Sergio , Bosco Luigi , Cioni Carla , Burani Paola 
Published: June 2005

AbstractLumbar ganglia innervating regenerating and normal hindlimbs were removed from larval Xenopus laevis at stage 56–57 (according to Nieuwkoop and Faber, '56) and implanted between the outer and inner corneas of larvae of the same species at stage 50. The control experiments consisted of implanting fragments of liver beneath the outer cornea or of merely separating the two corneas. Results show that the ganglia innervating regenerating limbs and normal ganglia can induce visible lens‐forming transformations in the outer cornea, although the percentage of successful cases obtained after the implant of normal ganglia is noticeably lower than that of the ganglia that innervate regenerating limbs. The results are interpreted as due to the action of a neurotrophic factor capable of replacing the action of the retinal factor(s) and produced either by ganglion cells that innervate regenerating limbs or by normal ganglion cells. Nevertheless, normal ganglia are thought to produce less of this substance than ganglia innervating regenerating limbs. No lens‐forming transformations have ever been found in the controls.
High survival of mouse embryos after rapid freezing and thawing inside plastic straws with 1–2 propanediol as cryoprotectant
Authors: Renard J. P. , Babinet C. 
Published: June 2005

AbstractA method for obtaining a high survival rate of frozen‐thawed mouse embryos is presented. Eight‐cell mouse embryos were frozen inside small plastic straws in the presence of 1–2 propanediol and stored at −196°C. After thawing, the embryos were diluted for only 5 min in a 1.0 M sucrose solution to remove the 1–2 propanediol from the cells. At high rate of thawing (∼2500°C/min) more than 88% of the embryos survived in vitro to the blastocyst stage provided that the dilution of propanediol was performed rapidly during thawing. At a lower rate of thawing (∼300°C/min), survival tended to be higher (94.7%) when dilution was done 5 min after thawing. When the frozen‐thawed embryos were transferred to the oviducts of day 1 pseudopregnant recipients either directly after the dilution of 1–2 propanediol or after 24 or 48 hr of culture, a high proportion of them (65.9%) develop normally to viable fetuses.
Local variation of the cell surface in chum salmon sperm as revealed by their agglutination reaction
Authors: Jaana Haruo , Yamamoto Tadashi S. 
Published: June 2005

AbstractThe sperm of the chum salmon, Oncorhynchus keta, possesses a bilaterally symmetrical organization by virtue of lateral extensions of the tail flagellum. An active movement of these sperm was induced immediately after incubation in well water but ceased within 2 min. A marked swelling of the cell body with coiling of the axoneme was observed during the incubation. Concanavalin A (Con A), Ricinus communis agglutinin (RCA60), and egg agglutinin from chum salmon eggs were able to induce sperm agglutination; reticular aggregates of the sperm were formed by the activity of egg agglutinin, whereas irregularly shaped clumps were produced by Con A and RCA60. Soybean agglutinin, Ulex europeus agglutinin, and wheat germ agglutinin were unable to induce sperm agglutination. Electron microscopy revealed that the aggregate or clump formations brought about by egg agglutinin and lectins are largely due to the elongation and entanglement of lateral extensions of different sperm flagella; no head‐to‐head attachment was observed. Although the aggregate formation by egg agglutinin was not inhibited by any of the sugar inhibitors used, sperm agglutination by Con A or RCA60 was blocked either by α‐methyl‐D‐mannoside or N‐acetyl‐D‐galactosamine. Con A binding sites of the cell surface detected by means of fluorescein isothiocyanate‐ or ferritin‐conjugated Con A were found to be restricted to the sperm tail, mostly to the surface of its lateral extensions. Polyethylene glycol also induced the elongation of lateral extensions of the tail flagellum; the actual fusion between different sperm occurred at the tips of these elongated extensions. No head‐to‐head or head‐to‐tail fusion was observed. We conclude that a local variation in the physiological property of the cell surface existing in the chum salmon sperm is correlated with the differential distribution of carbohydrate residues in the plasma membrane. These results in relation to early events in the fertilization of teleost eggs are discussed.
“Trophic” effect of transferrin on amphibian limb regeneration blastemas
Authors: Mescher Anthony L. , Munaim Syeda Iffat 
Published: June 2005

AbstractIn light of the recent demonstration that one “neurotrophic factor” of peripheral nerves is the iron‐transport glycoprotein transferrin, we tested the effects of heterologous transferrin on cellular events in cultured newt forelimb blastemas. Addition of transferrin to medium containing 1% fetal bovine serum resulted in DNA labeling and mitotic activity approximately twice as high as that of blastemas cultured in medium with 1% serum alone. Blastemas maintained for 24 hr in medium with 1% serum were stimulated to increased levels of DNA synthesis by the addition of transferrin, and this response was dose‐dependent. Varying the concentrations of iron and transferrin in the medium gave results indicating that the glycoprotein's trophic effect is due to its ability to furnish iron to the cells in an appropriate manner. Results of the study are consistent with the hypothesis that blastema cell proliferation is promoted by transferrin or transferrin‐like factors released from nerves.
Permeability of the integument of the horseshoe crab, Limulus polyphemus, to water, sodium, and bromide
Authors: Dunson William A. 
Published: June 2005

AbstractMean water movements across the double chitin membrane of the Limulus gill are 5,000–7,000 μmoles/cm2 · h. The carapace is much less permeable to water than the gill; this difference is probably due primarily to the greater thickness of the carapace. Variations in serum sodium concentration due to salinity changes do not affect the rates of water diffusion across the gills or carapace. The cause of a substantial variation between individuals in integumental water permeability is unknown. The sodium influx across the carapace of Limulus (0.7–1.6 μmoles/cm2 · h) is only a fraction that of the unidirectional water flux under the same conditions (0.5 M NaCl on both sides). This difference may be attributed to the greater size of the sodium ion in solution. There is no apparent effect of variations in carapace thickness on the sodium influx. The double chitin gill membrane is similarly low in sodium and bromide permeability (about 0.5–0.6 μmole/cm2 · h). Thus it appears that the gills may have a relatively passive role in ionic regulation. Their low rates of ionic diffusion help to restrict the loss or intake of salts as the salinity changes. However, the high gill permeability to water must pose a severe problem for an animal coping with changes in external salinity.
The sodium and chloride dependence of chloride secretion by the opercular epithelium
Authors: Degnan Kevin J. 
Published: June 2005

AbstractThe effects of ion substitutions on the Cl− secretion rate and tissue conductance of isolated short‐circuited opercular epithelia from sea‐water‐adapted Fundulus heteroclitus were investigated. Serosal Na+ substitution had the same effect on the Cl− secretion rate that serosal Cl− substitution had on the active component of the Cl− efflux. This similarity indicated a 1:1 Na‐Cl requirement for active Cl− secretion across this epithelium, which supports the proposal of a coupled NaCl uptake mechanism at the serosal membrane of Cl− secretory epithelia. Mucosal Na+ and Cl− substitutions appeared to inhibit completely the active Cl− secretory flux. The reductions in the tissue conductance with mucosal ion substitutions suggested that this effect can be attributed to a blocking of the apical membrane Cl− conductance. These mucosal ion effects suggested a possible direct regulatory influence of the external salinity on the Cl− secretion rate and tissue conductance, which provide alternative explanations for observations with the teleost gill epithelium.
Nucleoside triphosphate changes during the peripheral life‐span of erythrocytes of adult rainbow trout (Salmo gairdneri)
Authors: Lane Hugo C. 
Published: June 2005

AbstractDeterminations of nucleoside triphosphates (NTP) were made on rainbow trout erythrocytes segregated into age classes following velocity sedimentation at unit gravity. The NTP content of young cells was lower than that of mature cells, whereas it was significantly higher in the oldest cell population. Thin‐layer chromatography of erythrocyte cell extracts showed that both ATP and GTP were present and that the former dominated in all age groups. Potassium cyanide was significantly more effective than iodoacetate in lowering NTP levels in the cells of the young age class whereas in the oldest cells the reverse was true.
Histone acetylation and deacetylation of nuclei from sea urchin Hemicentrotus pulcherrimus embryos during early stages of development
Authors: Horiuchi Kentaro , Fujimoto Daisaburo , Uto Norihiko 
Published: June 2005

AbstractNuclei were isolated from sea urchin (Hemicentrotus pulcherrimus) embryos during early stages of development, and the rates of histone acetylation and deacetylation were examined. Histone acetylation was measured in the presence of 6 mM sodium n‐butyrate, a potent inhibitor of deacetylase, and in the absence of the inhibitor. The deacetylation activity was estimated from the difference between the rates with and without the inhibitor. The activities of the acetylation and the deacetylation, and the ratio of deacetylation to acetylation were unchanged during the stages between early blastula and gastrula. Autoradiographic analysis of acetylated histones showed that all of the internal histones of the nucleosomes were acetylated and that no apparent difference was found in the pattern of the acetylated fractions during the stages compared.
Mechanisms of flagellar motility deduced from backward‐swimming bull sperm
Authors: Phillips David M. , Kalay Dan 
Published: June 2005

AbstractUnder certain conditions of cryopreservation, bull spermatozoa undergo an interesting structural alteration. The sperm tail becomes bent back on itself to form a hairpin shape. The bend in the tail occurs at a very precise point, 11 μm behind the neck, and it causes the tail to become kinked. Flagellar microtubules and dense fibers become broken and the ninefold symmetry of the flagellum is greatly distored. Although the portion of the flagellum between the kink and the sperm head does not propagate a wave, the distal portion of the flagellum propagates a base‐to‐tip wave, causing the spermatozoan to progress backward. These observations suggest that the mammalian spermatozoon does not need basal structures to propagate a flagellar wave.